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Fibrosis results in one-third of all deaths globally and is a major healthcare challenge. Fibrosis is scarring caused by the excess deposition of extracellular matrix proteins by fibroblasts. Inhibition of pathways downstream of transforming growth factor β (TGF-β) a pluripotent growth factor, has potent antifibrotic effects in different organs. Here we show that loss of bone morphogenetic protein (BMP-3) is a feature of kidney fibrosis, independent of the initiating injury, suggesting loss of this cytokine is a core fibrotic mechanism. TGF-β decreased BMP3 expression in human fibroblasts is possibly a feed-forward loop that contributes to increased and sustained TGF-β activity. Recombinant human BMP-3 reduced TGF-β induced fibroblast contraction, migration and invasion, pathways that lead to scarring and tissue stiffening. BMP-3 reduced TGF-β stimulated collagen cross-linking, and Ox-LDL receptor 1, a regulator of collagen deposition. BMP-3 inhibited TGF-β stimulated lysyl oxidase activity. Lysyl oxidase mediated collagen cross-linking is a critical process in TGF-β induced fibrosis. We propose that BMP-3 alters fibroblast responses to TGF-β, shifting the balance from fibrosis to repair. Recombinant human BMP-3 shows promise for development as a novel therapeutic for fibrosis., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.)

The objective of this study is to explore whether sodium valproate (VPA) alleviates epileptic seizures via suppressing lysyl oxidase (Lox)-mediated ferroptosis. Epileptic seizure mouse model was prepared via intrahippocampal injection of kainic acid (250 ng/μl). After treatment with kainic acid, VPA was injected intraperitoneally by the dose of 250 mg/kg twice daily for 4 days. Ferroptosis-associated indices including lipid peroxides (LPO) level and Ptgs2 mRNA in hippocampal tissue samples were detected. Additionally, effects of VPA on Lox mRNA and enzymatic activity were assessed by quantitative real-time PCR and a commercial kit, respectively. Neuronal survival was assessed by Nissl staining. In kainic acid-induced epileptic seizure mouse model, VPA significantly suppressed LPO level and Ptgs2 mRNA and the suppression of ferroptosis was positively correlated with its anti-seizure effect. Lox mRNA and enzymatic activity were also found to decrease in hippocampus of epileptic seizure mice after VPA treatment. Furthermore, overexpression of Lox via adeno-associated virus infection remarkably abrogated the inhibitory effect of VPA on ferroptosis and neuronal impairment together with its anti-seizure effect. VPA suppresses Lox-mediated ferroptosis process, which can provide the explanation for its anti-seizure property., (Copyright © 2024 Wolters Kluwer Health, Inc. All rights reserved.)

In gastric cancer treatment, cancer-associated fibroblasts (CAF) may significantly influence the efficacy of immune checkpoint inhibitors by modulating PD-L1 expression. However, the precise mechanisms remain unclear. This study aims to explore the relationship between CAF and PD-L1 expression, providing new insights for improving PD-L1-targeted therapies. Using primary fibroblasts, transcriptome sequencing, ChIP-qPCR, and a lung metastasis model, we discovered that CAF secrete lysyl oxidase (LOX), which activates the TGFβ signaling pathway in gastric cancer cells, thereby promoting insulin-like growth factor 1(IGF1) expression. Upregulation of IGF1 enhances gastric cancer cell migration, epithelial-mesenchymal transition (EMT), and glycolysis. Additionally, we found that lactate accumulation leads to lysine 18 lactylation on histone H3 (H3K18la), which enriches at the PD-L1 promoter region, thus promoting PD-L1 transcription. These findings suggest that CAF may diminish the effectiveness of PD-1/PD-L1 blockade immunotherapy through LOX-induced glycolysis and lactate accumulation. Consequently, we have constructed a model of the interactions among CAF, lactate, and PD-L1 in gastric cancer progression, providing new experimental evidence for PD-L1-based immunotherapy., Competing Interests: Declaration of competing interest The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Lysyl oxidase (LOX) is upregulated in highly stiff aggressive tumors, correlating with metastasis, resistance, and worse survival; however, there are currently no potent, safe, and orally bioavailable small molecule LOX inhibitors to treat these aggressive desmoplastic solid tumors in clinics. Here we discovered bi-thiazole derivatives as potent LOX inhibitors by robust screening of drug-like molecules combined with cell/recombinant protein-based assays. Structure-activity relationship analysis identified a potent lead compound (LXG6403) with ∼3.5-fold specificity for LOX compared to LOXL2 while not inhibiting LOXL1 with a competitive, time- and concentration-dependent irreversible mode of inhibition. LXG6403 shows favorable pharmacokinetic properties, globally changes ECM/collagen architecture, and reduces tumor stiffness. This leads to better drug penetration, inhibits FAK signaling, and induces ROS/DNA damage, G1 arrest, and apoptosis in chemoresistant triple-negative breast cancer (TNBC) cell lines, PDX organoids, and in vivo. Overall, our potent and tolerable bi-thiazole LOX inhibitor enhances chemoresponse in TNBC, the deadliest breast cancer subtype., Competing Interests: Declaration of interests O. Sahin is the co-founder and manager of OncoCube Therapeutics LLC, founder and president of LoxiGen, and member of scientific advisory board of A2A Pharmaceuticals Inc. M.C., O. Saatci, A.-H.R., C.B., C.M., and O.S. are inventors on patent US 11,712,437., (Copyright © 2024 The Author(s). Published by Elsevier Ltd.. All rights reserved.)

Purpose: The lysyl oxidase (LOX) family has been implicated in the pathogenesis of diseases caused by inflammation and fibrosis. Therefore, we aimed to examine the role of lysyl oxidase-like protein 3 (LOXL3) in Graves' orbitopathy (GO) pathogenesis and its potential as a treatment target., Methods: Quantitative real-time polymerase chain reaction compared the transcript levels of the five LOX family subtypes in orbital tissue explants obtained from patients with GO (n = 18) and healthy controls (n = 15). The effects of LOXL3 inhibition on interleukin (IL)-1β-induced proinflammatory cytokines, transforming growth factor (TGF)-β-induced profibrotic proteins, intracellular signaling molecules, and adipogenic markers were evaluated using Western blotting. Adipogenic differentiation was identified using Oil Red O staining., Results: LOX and LOXL3 transcript levels were high in GO tissues. Stimulation with IL-1β, TGF-β, and insulin-like growth factor-1 significantly increased LOXL3 messenger RNA expression in GO fibroblasts. Furthermore, silencing LOXL3 attenuated the IL-1β-induced production of proinflammatory cytokines (IL-6, IL-8, and intercellular adhesion molecule-1) and TGF-β-induced production of profibrotic proteins (fibronectin, collagen 1α, and alpha-smooth muscle actin). It also reduced the IL-1β or TGF-β-induced expression of phosphorylated nuclear factor kappa-light-chain-enhancer of activated B cells, protein kinase B, extracellular signal-regulated kinase, and c-Jun N-terminal kinase. Additionally, LOXL3 silencing suppressed adipocyte differentiation and the expression of adipogenic transcription factors (leptin, AP-2, peroxisome proliferator-activated receptor gamma, and CCAAT/enhancer-binding protein)., Conclusions: LOXL3 is crucial in GO pathogenesis. LOXL3 inhibition reduced inflammatory cytokine production, fibrotic protein expression, and fibroblast differentiation into adipocytes. This study highlights LOXL3 as a potential therapeutic target for GO.

Purpose: To investigate the effect of reducing Lysyl oxidase (LOX) overexpression on retinal ganglion cells (RGCs) apoptosis in an acute ocular hypertension (AOH) rat model., Methods: AOH rat model was performed by anterior chamber perfusion and either received an intravitreal injection with β-aminopropionitrile (BAPN) or normal saline. After 2wk, Quantification of survival RGCs in the retina was performed using Retrograde FluoroGold labeling. The mRNA expression levels of LOX, LOXL1-4, collagen 1a1 (Col1a1), collagen 3a1 (Col3a1), collagen4a1 (Col4a1), elastin (Eln), fibronectin1 (Fbn1), fibronectin4 (Fbn4) were determined by RT-qPCR. LOX expression was determined by Western blot (WB) analysis and immunohistochemistry. The RNA expression of LOX, Eln and Col1a1 in RGCs retrograde-labeled with 1,1'-dioctadecyl-3,3,3',3' tetra-methylindocarbocyanine perchlorate(DiI)that selected through FACS sorting were determined by RT-qPCR analysis. Changes of the retinal function were detected by Electroretinogram (ERG) analysis., Results: Results showed that significant LOX overexpression and loss of RGCs related to IOP exposure in AOH retinas. PCR analysis indicated significant increased mRNA level of Col1a1, Col3al and Eln in AOH retinas. Significant increase mRNA expression of LOX, Col1a1 and Eln in the RGCs were observed in AOH group compared with CON group. AOH rats injected with BAPN showed a significant decrease in LOX expression, reduced the loss of RGCs and retinal function damage., Conclusions: The results demonstrated that changes of LOX and specific ECM components in retina were correlated with AOH. Findings from this study indicated that preventing LOX over-expression may be protective against RGCs loss and retinal function damage in AOH animal model.

Tumor-associated macrophages and microglia (TAMs) are critical for tumor progression and therapy resistance in glioblastoma (GBM), a type of incurable brain cancer. We previously identified lysyl oxidase (LOX) and olfactomedin like-3 (OLFML3) as essential macrophage and microglia chemokines, respectively, in GBM. Here, single-cell transcriptomics and multiplex sequential immunofluorescence followed by functional studies demonstrate that macrophages negatively correlate with microglia in the GBM tumor microenvironment. LOX inhibition in PTEN-deficient GBM cells upregulates OLFML3 expression via the NF-κB-PATZ1 signaling pathway, inducing a compensatory increase of microglia infiltration. Dual targeting macrophages and microglia via inhibition of LOX and the CLOCK-OLFML3 axis generates potent antitumor effects and offers a complete tumor regression in more than 60% of animals when combined with anti-PD1 therapy in PTEN-deficient GBM mouse models. Thus, our findings provide a translational triple therapeutic strategy for this lethal disease.

Background and Aims: Lysyl oxidase (LOX) catalyzes the crosslinking of collagen and elastin to maintain tensile strength and structural integrity of the vasculature. Excessive LOX activity increases vascular stiffness and the severity of occlusive diseases. Herein, we investigated the mechanisms by which LOX controls atherogenesis and osteogenic differentiation of vascular smooth muscle cells (SMC) in hyperlipidemic mice., Methods: Gene inactivation of Lox in SMC was achieved in conditional knockout mice after tamoxifen injections. Atherosclerosis burden and vascular calcification were assessed in hyperlipidemic conditional [Lox f/f Myh11-CreER T2 ApoE -/- ] and sibling control mice [Lox wt/wt Myh11-CreER T2 ApoE -/- ]. Mechanistic studies were performed with primary aortic SMC from Lox mutant and wild type mice., Results: Inactivation of Lox in SMCs decreased > 70 % its RNA expression and protein level in the aortic wall and significantly reduced LOX activity without compromising vascular structure and function. Moreover, LOX deficiency protected mice against atherosclerotic burden (13 ± 2 versus 23 ± 1 %, p < 0.01) and plaque calcification (5 ± 0.4 versus 11.8 ± 3 %, p < 0.05) compared to sibling controls. Interestingly, gene inactivation of Lox in SMCs preserved the contractile phenotype of vascular SMC under hyperlipidemic conditions as demonstrated by single-cell RNA sequencing and immunofluorescence. Mechanistically, the absence of LOX in SMC prevented excessive collagen crosslinking and the subsequent activation of the pro-osteogenic FAK/β-catenin signaling axis., Conclusions: Lox inactivation in SMC protects mice against atherosclerosis and plaque calcification by reducing SMC modulation and FAK/β-catenin signaling., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Published by Elsevier B.V.)

Hypoxic-ischemic encephalopathy (HIE) poses a significant challenge in neonatal medicine, often resulting in profound and lasting neurological deficits. Current therapeutic strategies for hypoxia-ischemia brain damage (HIBD) remain limited. Ferroptosis has been reported to play a crucial role in HIE and serves as a potential therapeutic target. However, the mechanisms underlying ferroptosis in HIBD remain largely unclear. In this study, we found that elevated lysyl oxidase (LOX) expression correlates closely with the severity of HIE, suggesting LOX as a potential biomarker for HIE. LOX expression levels and enzymatic activity were significantly increased in HI-induced neuronal models both in vitro and in vivo. Notably, we discovered that HI-induced brain tissue injury results in increased stiffness and observed a selective upregulation of the mechanosensitive ion channel Piezo1 in both brain tissue of HIBD and primary cortex neurons. Mechanistically, LOX increases its catalytic substrates, the Collagen I/III components, promoting extracellular matrix (ECM) remodeling and possibly mediating ECM cross-linking, which leads to increased stiffness at the site of injury and subsequent activation of the Piezo1 channel. Piezo1 senses these stiffness stimuli and then induces neuronal ferroptosis in a GPX4-dependent manner. Pharmacological inhibition of LOX or Piezo1 ameliorated brain neuronal ferroptosis and improved learning and memory impairments. Furthermore, we identified traumatic acid (TA) as a novel LOX inhibitor that effectively suppresses LOX enzymatic activity, mitigating neuronal ferroptosis and promoting synaptic plasticity. In conclusion, our findings elucidate a critical role for LOX-mediated ECM mechanical stress-induced Piezo1 activation in regulating ferroptotic cell death in HIBD. This mechanistic insight provides a basis for developing targeted therapies aimed at ameliorating neurological outcomes in neonates affected by HIBD., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier B.V. All rights reserved.)

Background: Atrial fibrosis is one of the main causes of the onset and recurrence of atrial fibrillation (AF), for which there is no effective treatment. The aim of this study was to investigate the effect and mechanism of epigallocatechin-3-gallate (EGCG) on AF in rats., Methods: The rat model of AF was established by rapid pacing induction after angiotensin-II (Ang-II) induced atrial fibrosis to verify the relationship between atrial fibrosis and the AF. The expression levels of TGF-β/Smad3 pathway molecules and lysyl oxidase (LOX) in AF were detected. Subsequently, EGCG was used to intervene Ang-II-induced atrial fibrosis to explore the role of EGCG in the treatment of AF and its inhibitory mechanism on fibrosis. It was further verified that EGCG inhibited the production of collagen and the expression of LOX through the TGF-β/Smad3 pathway at the cellular level., Results: The results showed that the induction rate and maintenance time of AF in rats increased with the increase of the degree of atrial fibrosis. Meanwhile, the expressions of Col I, Col III, molecules related to TGF-β/Smad3 pathway, and LOX increased significantly in the atrial tissues of rats in the Ang-II induced group. EGCG could reduce the occurrence and maintenance time of AF by inhibiting the degree of Ang-induced rat atrial fibrosis. Cell experiments confirmed that EGCG could reduce the synthesis of collagen and the expression of LOX in cardiac fibroblast induced by Ang-II. The possible mechanism is to down-regulate the expression of genes and proteins related to the TGF-β/Smad3 pathway., Conclusion: EGCG could downregulate the expression levels of collagen and LOX by inhibiting the TGF-β/Smad3 signaling pathway, alleviating Ang-II-induced atrial fibrosis, which in turn inhibited the occurrence and curtailed the duration of AF., (© 2023. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)

Background: The stiffness of the tumor microenvironment (TME) directly influences cellular behaviors. Radiotherapy (RT) is a common treatment for solid tumors, but the TME can impact its efficacy. In the case of liver cancer, clinical observations have shown that tumors within a cirrhotic, stiffer background respond less to RT, suggesting that the extracellular matrix (ECM) stiffness plays a critical role in the development of radioresistance., Methods: This study explored the effects of ECM stiffness and the inhibition of lysyl oxidase (LOX) isoenzymes on the radiation response of liver cancer in a millimeter-sized three-dimensional (3D) culture. We constructed a cube-shaped ECM-based millimeter-sized hydrogel containing Huh7 human liver cancer cells. By modulating the collagen concentration, we produced two groups of samples with different ECM stiffnesses to mimic the clinical scenarios of normal and cirrhotic livers. We used a single-transducer system for shear-wave-based elasticity measurement, to derive Young's modulus of the 3D cell culture to investigate how the ECM stiffness affects radiosensitivity. This is the first demonstration of a workflow for assessing radiation-induced response in a millimeter-sized 3D culture., Results: Increased ECM stiffness was associated with a decreased radiation response. Moreover, sonoporation-assisted LOX inhibition with BAPN (β-aminopropionitrile monofumarate) significantly decreased the initial ECM stiffness and increased RT-induced cell death. Inhibition of LOX was particularly effective in reducing ECM stiffness in stiffer matrices. Combining LOX inhibition with RT markedly increased radiation-induced DNA damage in cirrhotic liver cancer cells, enhancing their response to radiation. Furthermore, LOX inhibition can be combined with sonoporation to overcome stiffness-related radioresistance, potentially leading to better treatment outcomes for patients with liver cancer., Conclusions: The findings underscore the significant influence of ECM stiffness on liver cancer's response to radiation. Sonoporation-aided LOX inhibition emerges as a promising strategy to mitigate stiffness-related resistance, offering potential improvements in liver cancer treatment outcomes., (© 2024. The Author(s).)

Background/aims: Gastric cancer (GC) ranks among the prevalent types of cancer, and its progression is influenced by the tumor microenvironment (TME). A comprehensive comprehension of the TME associated with GC has the potential to unveil therapeutic targets of significance., Methods: The complexity and heterogeneity of TME interactions were revealed through our investigation using an integrated analysis of single-cell and bulk-tissue sequencing data., Results: We constructed a single-cell transcriptomic atlas of 150,913 cells isolated from GC patients. Our analysis revealed the intricate nature and heterogeneity of the GC TME and the metabolic properties of major cell types. Furthermore, two cell subtypes, LOX + Fibroblasts and M2 Macrophages, were enriched in tumor tissue and related to the outcome of GC patients. In addition, LOX + Fibroblasts were significantly associated with M2 macrophages. immunofluorescence double labeling indicated LOX + Fibroblasts and M2 Macrophages were tightly localized in GC tissue. The two cell subpopulations strongly interacted in a hypoxic microenvironment, yielding an immunosuppressive phenotype. Our findings further suggest that LOX + Fibroblasts may act as a trigger for inducing the differentiation of monocytes into M2 Macrophages via the IL6-IL6R signaling pathway., Conclusions: Our study revealed the intricate and interdependent communication network between the fibroblast and macrophage subpopulations, which could offer valuable insights for targeted manipulation of the tumor microenvironment., (© 2024. The Author(s).)

Introduction: Cardiovascular calcification is an important public health issue with an unmeet therapeutic need. We had previously shown that lysyl oxidase (LOX) activity critically influences vascular wall smooth muscle cells (VSMCs) and valvular interstitial cells (VICs) calcification by affecting extracellular matrix remodeling. We have delved into the participation of LOX in atherosclerosis and vascular calcification, as well as in the mineralization of the aortic valve., Methods: Immunohistochemical and expression studies were carried out in human atherosclerotic lesions and experimental models, valves from patients with aortic stenosis, VICs, and in a genetically modified mouse model that overexpresses LOX in CMLV (TgLOX CMLV ). Hyperlipemia and atherosclerosis was induced in mice through the administration of adeno-associated viruses encoding a PCSK9 mutated form (AAV-PCSK9 D374Y ) combined with an atherogenic diet., Results: LOX expression is increased in the neointimal layer of atherosclerotic lesions from human coronary arteries and in VSMC-rich regions of atheromas developed both in the brachiocephalic artery of control (C57BL/6J) animals transduced with PCSK9 D374Y and in the aortic root of ApoE -/- mice. In TgLOX CMLV mice, PCSK9 D374Y transduction did not significantly alter the enhanced aortic expression of genes involved in matrix remodeling, inflammation, oxidative stress and osteoblastic differentiation. Likewise, LOX transgenesis did not alter the size or lipid content of atherosclerotic lesions in the aortic arch, brachiocephalic artery and aortic root, but exacerbated calcification. Among lysyl oxidase isoenzymes, LOX is the most expressed member of this family in highly calcified human valves, colocalizing with RUNX2 in VICs. The lower calcium deposition and decreased RUNX2 levels triggered by the overexpression of the nuclear receptor NOR-1 in VICs was associated with a reduction in LOX., Conclusions: Our results show that LOX expression is increased in atherosclerotic lesions, and that overexpression of this enzyme in VSMC does not affect the size of the atheroma or its lipid content, but it does affect its degree of calcification. Further, these data suggest that the decrease in calcification driven by NOR-1 in VICs would involve a reduction in LOX. These evidences support the interest of LOX as a therapeutic target in cardiovascular calcification., (Copyright © 2024 Sociedad Española de Arteriosclerosis. Publicado por Elsevier España, S.L.U. All rights reserved.)

Nitric oxide (NO) is an important gas messenger molecule with a wide range of biological functions. High concentration of NO exerts promising antitumor effects and is regarded as one of the hot spots in cancer research, that have limitations in their direct application due to its gaseous state, short half-life (seconds) and high reactivity. Lysyl oxidase (LOX) is a copper-dependent amine oxidase that is responsible for the covalent bonding between collagen and elastin and promotes tumor cell invasion and metastasis. The overexpression of LOX in triple-negative breast cancer (TNBC) makes it an attractive target for TNBC therapy. Herein, novel NO donor prodrug molecules were designed and synthesized based on the naturally derived piperlongumine (PL) skeleton, which can be selectively activated by LOX to release high concentrations of NO and PL derivatives, both of them play a synergistic role in TNBC therapy. Among them, the compound TM-1 selectively released NO in highly invasive TNBC cells (MDA-MB-231), and TM-1 was also confirmed as a potential TNBC cell line inhibitor with an inhibitory concentration of 2.274 μM. Molecular docking results showed that TM-1 had a strong and selective binding affinity with LOX protein., Competing Interests: Declaration of competing interest The authors declare no conflict of interest., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Chondrosarcoma is a malignant bone tumor that emerges from abnormalities in cartilaginous tissue and is related with lung metastases. Nicotinamide phosphoribosyltransferase (NAMPT) is an adipocytokine reported to enhance tumor metastasis. Our results from clinical samples and the Gene Expression Omnibus data set reveal that NAMPT levels are markedly higher in chondrosarcoma patients than in normal individuals. NAMPT stimulation significantly increased lysyl oxidase (LOX) production in chondrosarcoma cells. Additionally, NAMPT increased LOX-dependent cell migration and invasion in chondrosarcoma by suppressing miR-26b-5p generation through the c-Src and Akt signaling pathways. Overexpression of NAMPT promoted chondrosarcoma metastasis to the lung in vivo. Furthermore, knockdown of LOX counteracted NAMPT-facilitated metastasis. Thus, the NAMPT/LOX axis presents a novel target for treating the metastasis of chondrosarcoma., (© 2024 Wiley Periodicals LLC.)

Pulmonary fibrosis (PF) is a clinically severe and commonly fatal complication of Systemic Sclerosis (SSc). Our group has previously reported profibrotic roles for Insulin-like Growth Factor II (IGF-II) and Lysyl Oxidase (LOX) in SSc-PF. We sought to identify downstream regulatory mediators of IGF-II. In the present work, we show that SSc lung tissues have higher baseline levels of the total (N-glycosylated/unglycosylated) LOX-Propeptide (LOX-PP) than control lung tissues. LOX-PP-mediated changes were consistent with the extracellular matrix (ECM) deregulation implicated in SSc-PF progression. Furthermore, Tolloid-like 1 (TLL1) and Bone Morphogenetic Protein 1 (BMP1), enzymes that can cleave ProLOX to release LOX-PP, were increased in SSc lung fibrosis and the bleomycin (BLM)-induced murine lung fibrosis model, respectively. In addition, IGF-II regulated the levels of ProLOX, active LOX, LOX-PP, BMP1, and isoforms of TLL1. The Class E Basic Helix-Loop-Helix protein 40 (BHLHE40) transcription factor localized to the nucleus in response to IGF-II. BHLHE40 silencing downregulated TLL1 isoforms and LOX-PP, and restored features of ECM deregulation triggered by IGF-II. Our findings indicate that IGF-II, BHLHE40, and LOX-PP may serve as targets of therapeutic intervention to halt SSc-PF progression., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Objective: This study aimed to investigate the effect of plasma-activated Ringer's lactate solution (PAL) on oral squamous cell carcinoma (OSCC) cells and carcinogenic processes with a particular focus on iron and collagenous matrix formation., Materials and Methods: We used three OSCC cell lines, one keratinocyte cell line, and two fibroblast lines, and cell viability assays, immunoblotting, flow cytometry, and transmission electron microscopy were performed to evaluate the effect and type of cell death. The effect of PAL treatment on lysyl oxidase (LOX) expression was investigated in vitro and in vivo. Tamoxifen-inducible Mob1a/b double-knockout mice were used for the in vivo experiment., Results: PAL killed OSCC cells more effectively than the control nontumorous cells and suppressed cell migration and invasion. Ferroptosis occurred and the protein level of LOX was downregulated in cancer cells in vitro and in vivo. Additionally, PAL improved the survival rate of mice and suppressed collagenous matrix formation., Conclusions: We demonstrated that PAL specifically kills OSCC cells and that ferroptosis occurs in vitro and in vivo. Furthermore, PAL can prevent carcinogenesis and improve the survival rate of oral cancer, especially tongue cancer, by changing collagenous matrix formation via LOX suppression., (© 2023 The Authors. Oral Diseases published by Wiley Periodicals LLC.)

The intima, comprising the endothelium and the subendothelial matrix, plays a crucial role in atherosclerosis pathogenesis. The mechanical stress arising from disturbed blood flow (d-flow) and the stiffening of the arterial wall contributes to endothelial dysfunction. However, the specific impacts of these physical forces on the mechanical environment of the intima remain undetermined. Here, we investigated whether inhibiting collagen crosslinking could ameliorate the detrimental effects of persistent d-flow on the mechanical properties of the intima. Partial ligation of the left carotid artery (LCA) was performed in C57BL/6J mice, inducing d-flow. The right carotid artery (RCA) served as an internal control. Carotids were collected 2 days and 2 weeks after surgery to study acute and chronic effects of d-flow on the mechanical phenotype of the intima. The chronic effects of d-flow were decoupled from the ensuing arterial wall stiffening by administration of β-aminopropionitrile (BAPN), an inhibitor of collagen crosslinking by lysyl oxidase (LOX) enzymes. Atomic force microscopy (AFM) was used to determine stiffness of the endothelium and the denuded subendothelial matrix in en face carotid preparations. The stiffness of human aortic endothelial cells (HAEC) cultured on soft and stiff hydrogels was also determined. Acute exposure to d-flow caused a slight decrease in endothelial stiffness in male mice but had no effect on the stiffness of the subendothelial matrix in either sex. Regardless of sex, the intact endothelium was softer than the subendothelial matrix. In contrast, exposure to chronic d-flow led to a substantial increase in the endothelial and subendothelial stiffness in both sexes. The effects of chronic d-flow were largely prevented by concurrent BAPN administration. In addition, HAEC displayed reduced stiffness when cultured on soft vs. stiff hydrogels. We conclude that chronic d-flow results in marked stiffening of the arterial intima, which can be effectively prevented by inhibition of collagen crosslinking., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2024 Bywaters, Trache and Rivera.)

Background: Lysyl oxidase enzymes (LOXs), as extracellular matrix (ECM) protein regulators, play vital roles in tumor progression by remodeling the tumor microenvironment. However, their roles in glioblastoma (GBM) have not been fully elucidated., Methods: The genetic alterations and prognostic value of LOXs were investigated via cBioPortal. The correlations between LOXs and biological functions/molecular tumor subtypes were explored in The Cancer Genome Atlas (TCGA) and the Chinese Glioma Genome Atlas (CGGA). After Kaplan‒Meier and Cox survival analyses, a Loxl1-based nomogram and prognostic risk score model (PRSM) were constructed and evaluated by time-dependent receiver operating characteristic curves, calibration curves, and decision curve analyses. Tumor enrichment pathways and immune infiltrates were explored by single-cell RNA sequencing and TIMER. Loxl1-related changes in tumor viability/proliferation and invasion were further validated by CCK-8, western blot, wound healing, and Transwell invasion assays., Results: GBM patients with altered LOXs had poor survival. Upregulated LOXs were found in IDH1-wildtype and mesenchymal (not Loxl1) GBM subtypes, promoting ECM receptor interactions in GBM. The Loxl1-based nomogram and the PRSM showed high accuracy, reliability, and net clinical benefits. Loxl1 expression was related to tumor invasion and immune infiltration (B cells, neutrophils, and dendritic cells). Loxl1 knockdown suppressed GBM cell proliferation and invasion by inhibiting the EMT pathway (through the downregulation of N-cadherin/Vimentin/Snai1 and the upregulation of E-cadherin)., Conclusion: The Loxl1-based nomogram and PRSM were stable and individualized for assessing GBM patient prognosis, and the invasive role of Loxl1 could provide a promising therapeutic strategy., Competing Interests: The authors declare that they have no competing interests., (© 2024 Yuan et al.)

Background: β-aminopropionitrile (BAPN) is a pharmacological inhibitor of LOX (lysyl oxidase) and LOXLs (LOX-like proteins). Administration of BAPN promotes aortopathies, although there is a paucity of data on experimental conditions to generate pathology. The objective of this study was to define experimental parameters and determine whether equivalent or variable aortopathies were generated throughout the aortic tree during BAPN administration in mice., Methods: BAPN was administered in drinking water for a period ranging from 1 to 12 weeks. The impacts of BAPN were first assessed with regard to BAPN dose, and mouse strain, age, and sex. BAPN-induced aortic pathological characterization was conducted using histology and immunostaining. To investigate the mechanistic basis of regional heterogeneity, the ascending and descending thoracic aortas were harvested after 1 week of BAPN administration before the appearance of overt pathology., Results: BAPN-induced aortic rupture predominantly occurred or originated in the descending thoracic aorta in young C57BL/6J or N mice. No apparent differences were found between male and female mice. For mice surviving 12 weeks of BAPN administration, profound dilatation was consistently observed in the ascending region, while there were more heterogeneous changes in the descending thoracic region. Pathological features were distinct between the ascending and descending thoracic regions. Aortic pathology in the ascending region was characterized by luminal dilatation and elastic fiber disruption throughout the media. The descending thoracic region frequently had dissections with false lumen formation, collagen deposition, and remodeling of the wall surrounding the false lumen. Cells surrounding the false lumen were predominantly positive for α-SMA (α-smooth muscle actin). One week of BAPN administration compromised contractile properties in both regions equivalently, and RNA sequencing did not show obvious differences between the 2 aortic regions in smooth muscle cell markers, cell proliferation markers, and extracellular components., Conclusions: BAPN-induced pathologies show distinct, heterogeneous features within and between ascending and descending aortic regions in mice., Competing Interests: Disclosures None.

Tendons are frequently injured and have limited regenerative capacity. This motivates tissue engineering efforts aimed at restoring tendon function through strategies to direct functional tendon formation. Generation of a crosslinked collagen matrix is paramount to forming mechanically functional tendon. However, it is unknown how lysyl oxidase (LOX), the primary mediator of enzymatic collagen crosslinking, is regulated by stem cells. This study investigates how multiple factors previously identified to promote tendon formation and healing (transforming growth factor [TGF]β1 and TGFβ2, mechanical stimuli, and hypoxia-inducible factor [HIF]-1α) regulate LOX production in the murine C3H10T1/2 mesenchymal stem cell (MSC) line. We hypothesized that TGFβ signaling promotes LOX activity in C3H10T1/2 MSCs, which is regulated by both mechanical stimuli and HIF-1α activation. TGFβ1 and TGFβ2 increased LOX levels as a function of concentration and time. Inhibiting the TGFβ type I receptor (TGFβRI) decreased TGFβ2-induced LOX production by C3H10T1/2 MSCs. Low (5 mPa) and high (150 mPa) magnitudes of fluid shear stress were applied to test impacts of mechanical stimuli, but without TGFβ2, loading alone did not alter LOX levels. Low loading (5 mPa) with TGFβ2 increased LOX at 7 days greater than TGFβ2 treatment alone. Neither HIF-1α knockdown (siRNA) nor activation (CoCl 2 ) affected LOX levels. Ultimately, results suggest that TGFβ2 and appropriate loading magnitudes contribute to LOX production by C3H10T1/2 MSCs. Potential application of these findings includes treatment with TGFβ2 and appropriate mechanical stimuli to modulate LOX production by stem cells to ultimately control collagen matrix stiffening and support functional tendon formation.

Two major constituents of exfoliation material, fibrillin-1 and lysyl oxidase-like 1 (encoded by FBN1 and LOXL1), are implicated in exfoliation glaucoma, yet their individual contributions to ocular phenotype are minor. To test the hypothesis that a combination of FBN1 mutation and LOXL1 deficiency exacerbates ocular phenotypes, the pan-lysyl oxidase inhibitor β-aminopropionitrile (BAPN) was used to treat adult wild-type (WT) mice and mice heterozygous for a missense mutation in Fbn1 (Fbn1 C1041G /+ ) for 8 weeks and their eyes were examined. Although intraocular pressure did not change and exfoliation material was not detected in the eyes, BAPN treatment worsened optic nerve and axon expansion in Fbn1 C1041G/+ mice, an early sign of axonal damage in rodent models of glaucoma. Disruption of elastic fibers was detected only in Fbn1 C1041G/+ mice, which increased with BAPN treatment, as shown by histologic and immunohistochemical staining of the optic nerve pia mater. Transmission electron microscopy showed that Fbn1 C1041G/+ mice had fewer microfibrils, smaller elastin cores, and a lower density of elastic fibers compared with WT mice in control groups. BAPN treatment led to elastin core expansion in both WT and Fbn1 C1041G/+ mice, but an increase in the density of elastic fiber was confined to Fbn1 C1041G/+ mice. LOX inhibition had a stronger effect on optic nerve and elastic fiber parameters in the context of Fbn1 mutation, indicating the Marfan mouse model with LOX inhibition warrants further investigation for exfoliation glaucoma pathogenesis., Competing Interests: Disclosure Statement None declared., (Copyright © 2024 American Society for Investigative Pathology. Published by Elsevier Inc. All rights reserved.)

Abstract: Lysyl oxidase (LOX) is a facilitator of extracellular matrix cross-linking. Using newly developed megakaryocyte-specific LOX knockout mice, we show that LOX expressed in these scarce bone marrow cells affects bone volume and collagen architecture in a sex-dependent manner., (© 2024 American Society of Hematology. Published by Elsevier Inc. All rights are reserved, including those for text and data mining, AI training, and similar technologies.)

Background: Proliferative diabetic retinopathy (PDR) is a major cause of irreversible blindness in the working age population. The dysfunction of retinal vascular endothelial cells (RVECs) is the primary cause of PDR. Extracellular matrix (ECM) accumulation promotes intracellular signaling required for RVEC proliferation, migration, survival, and tube morphogenesis., Objectives: This study aimed to investigate the role of lysyl oxidase (LOX) in the cellular function of RVECs and PDR pathogenesis and to identify the underlying mechanisms., Material and Methods: Protein expression was determined with western blot. The interaction between LOX and elastin (ELN) was detected using a co-immunoprecipitation (Co-IP) assay, and the Cell Counting Kit-8 (CCK-8) assay evaluated cell viability. A colony formation assay was employed to assess the proliferation of human RVECs (hRVECs), and a transwell assay to determine their migration ability. Streptozotocin was used to establish PDR in mice in vivo. A histological analysis was conducted using hematoxylin and eosin (H&E) staining., Results: The results showed that LOX was overexpressed in PDR patients. The LOX knockdown suppressed ECM formation and hRVEC proliferation and migration. Additionally, LOX upregulated ELN expression. However, overexpressed ELN promoted hRVEC proliferation and migration. In vivo experiments showed that curcumin-mediated LOX deficiency restored retinal tissue structure., Conclusions: The LOX-knockdown suppressed ECM formation and hRVEC proliferation and migration by inactivating ELN. Therefore, LOX/ELN signaling may be a potential PDR biomarker.

Collagen crosslinking, mediated by lysyl oxidase, is an adaptive mechanism of the cardiac repair process initiated by cardiac fibroblasts postmyocardial injury. However, excessive crosslinking leads to cardiac wall stiffening, which impairs the contractile properties of the left ventricle and leads to heart failure. In this study, we investigated the role of periostin, a matricellular protein, in the regulation of lysyl oxidase in cardiac fibroblasts in response to angiotensin II and TGFβ1. Our results indicated that periostin silencing abolished the angiotensin II and TGFβ1-mediated upregulation of lysyl oxidase. Furthermore, the attenuation of periostin expression resulted in a notable reduction in the activity of lysyl oxidase. Downstream of periostin, ERK1/2 MAPK signaling was found to be activated, which in turn transcriptionally upregulates the serum response factor to facilitate the enhanced expression of lysyl oxidase. The periostin-lysyl oxidase association was also positively correlated in an in vivo rat model of myocardial infarction. The expression of periostin and lysyl oxidase was upregulated in the collagen-rich fibrotic scar tissue of the left ventricle. Remarkably, echocardiography data showed a reduction in the left ventricular wall movement, ejection fraction, and fractional shortening, indicative of enhanced stiffening of the cardiac wall. These findings shed light on the mechanistic role of periostin in the collagen crosslinking initiated by activated cardiac fibroblasts. Our findings signify periostin as a possible therapeutic target to reduce excessive collagen crosslinking that contributes to the structural remodeling associated with heart failure., (© 2024 John Wiley & Sons Ltd.)

Epilepsy-associated cognitive disorder (ECD), a prevalent comorbidity in epilepsy patients, has so far uncharacterized etiological origins. Our prior work revealed that lysyl oxidase (Lox) acted as a novel contributor of ferroptosis, a recently discovered cell death mode in the regulation of brain function. However, the role of Lox-mediated ferroptosis in ECD remains unknown. ECD mouse model was established 2 months later following a single injection of kainic acid (KA) for. After chronic treatment with KA, mice were treated with different doses (30 mg/kg, 100 mg/kg and 300 mg/kg) of Lox inhibitor BAPN. Additionally, hippocampal-specific Lox knockout mice was also constructed and employed to validate the role of Lox in ECD. Cognitive functions were assessed using novel object recognition test (NOR) and Morris water maze test (MWM). Protein expression of phosphorylated cAMP-response element binding (CREB), a well-known molecular marker for evaluation of cognitive performance, was also detected by Western blot. The protein distribution of Lox was analyzed by immunofluorescence. In KA-induced ECD mouse model, ferroptosis process was activated according to upregulation of 4-HNE protein and a previously discovered ferroptosis in our group, namely, Lox was remarkably increased. Pharmacological inhibition of Lox by BAPN at the dose of 100 mg/kg significantly increased the discrimination index following NOR test and decreased escape latency as well as augmented passing times within 60 s following MWM test in ECD mouse model. Additionally, deficiency of Lox in hippocampus also led to pronounced improvement of deficits in ECD model. These findings indicate that the ferroptosis regulatory factor, Lox, is activated in ECD. Ablation of Lox by either pharmacological intervention or genetic manipulation ameliorates the impairment in ECD mouse model, which suggest that Lox serves as a promising therapeutic target for treating ECD in clinic., Competing Interests: Declaration of Competing Interest I represent all the authors declare that there is no potential conflict of interest to declare in this study., (Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.)

Background & Aims: Metabolic and transcriptional programs respond to extracellular matrix-derived cues in complex environments, such as the tumor microenvironment. Here, we demonstrate how lysyl oxidase (LOX), a known factor in collagen crosslinking, contributes to the development and progression of cholangiocarcinoma (CCA)., Methods: Transcriptomes of 209 human CCA tumors, 143 surrounding tissues, and single-cell data from 30 patients were analyzed. The recombinant protein and a small molecule inhibitor of the LOX activity were used on primary patient-derived CCA cultures to establish the role of LOX in migration, proliferation, colony formation, metabolic fitness, and the LOX interactome. The oncogenic role of LOX was further investigated by RNAscope and in vivo using the AKT/NICD genetically engineered murine CCA model., Results: We traced LOX expression to hepatic stellate cells and specifically hepatic stellate cell-derived inflammatory cancer-associated fibroblasts and found that cancer-associated fibroblast-driven LOX increases oxidative phosphorylation and metabolic fitness of CCA, and regulates mitochondrial function through transcription factor A, mitochondrial. Inhibiting LOX activity in vivo impedes CCA development and progression. Our work highlights that LOX alters tumor microenvironment-directed transcriptional reprogramming of CCA cells by facilitating the expression of the oxidative phosphorylation pathway and by increasing stemness and mobility., Conclusions: Increased LOX is driven by stromal inflammatory cancer-associated fibroblasts and correlates with diminished survival of patients with CCA. Modulating the LOX activity can serve as a novel tumor microenvironment-directed therapeutic strategy in bile duct pathologies., (Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.)

Tissue repair and fibrosis involve the dynamic remodeling of collagen, and accurate detection of these sites is of utmost importance. Here, we use a collagen peptide sensor (1) to visualize collagen formation and remodeling during wound healing in mice and humans. We show that the probe binds selectively to sites of collagen formation and remodeling at different stages of healing. Compared to conventional methods, the peptide sensor localizes preferentially to areas of collagen synthesis and remodeling at the wound edge and not in matured fibrillar collagen. We also demonstrate its applicability for in vivo wound imaging and for discerning differential remodeling in wounds of transgenic mice with altered collagen dynamics. Our findings show the value of 1 as a diagnostic tool to rapidly identify the sites of matrix remodeling in tissue sections, which will aid in the conception of new therapeutic strategies for fibrotic disorders and defective tissue repair., Competing Interests: Declaration of competing interest The authors have no competing interests., (Copyright © 2024. Published by Elsevier B.V.)

Mammalian members of the lysyl oxidase (LOX) family of proteins carry a copper-dependent monoamine oxidase domain exclusively within the C-terminal region, which catalyzes ε-amine oxidation of lysine residues of various proteins. However, recent studies have demonstrated that in LOX-like (LOXL) 2-4 the C-terminal canonical catalytic domain and N-terminal scavenger receptor cysteine-rich (SRCR) repeats domain exhibit lysine deacetylation and deacetylimination catalytic activities. Moreover, the N-terminal SRCR repeats domain is more catalytically active than the C-terminal oxidase domain. Thus, LOX is the third family of lysine deacetylases in addition to histone deacetylase and sirtuin families. In this review, we discuss how the LOX family targets different cellular proteins for deacetylation and deacetylimination to control the development and metastasis of cancer., (©2024 American Association for Cancer Research.)

Lysyl oxidases (LOX(L)) are enzymes that catalyze the formation of cross-links in collagen and elastin fibers during physiologic calcification of bone. However, it remains unknown whether they may promote pathologic calcification of articular cartilage, an important hallmark of debilitating arthropathies. Here, we have studied the possible roles of LOX(L) in cartilage calcification, related and not related to their cross-linking activity. We first demonstrated that inhibition of LOX(L) by β-aminoproprionitrile (BAPN) significantly reduced calcification in murine and human chondrocytes, and in joint of meniscectomized mice. These BAPN's effects on calcification were accounted for by different LOX(L) roles. Firstly, reduced LOX(L)-mediated extracellular matrix cross-links downregulated Anx5, Pit1 and Pit2 calcification genes. Secondly, BAPN reduced collagen fibrotic markers Col1 and Col3. Additionally, LOX(L) inhibition blocked chondrocytes hypertrophic differentiation (Runx2 and COL10), pro-inflammatory IL-6 release and reactive oxygen species (ROS) production, all triggers of chondrocyte calcification. Through unbiased transcriptomic analysis we confirmed a positive correlation between LOX(L) genes and genes for calcification, hypertrophy and extracellular matrix catabolism. This association was conserved throughout species (mouse, human) and tissues that can undergo pathologic calcification (kidney, arteries, skin). Overall, LOX(L) play a critical role in the process of chondrocyte calcification and may be therapeutic targets to treat cartilage calcification in arthropathies., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier Masson SAS.. All rights reserved.)

Purpose: To investigate collagen I, collagen V, nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB), lysyl oxidase (LOX), transforming growth factor β1 (TGF-β1) and interleukin-6 (IL-6) expression in healthy and keratoconus human corneal fibroblasts (HCFs and KC-HCFs), 24 h after Rose Bengal photodynamic therapy (RB-PDT)., Methods: HCFs were isolated from healthy human corneal donors ( n  = 5) and KC-HCFs from elective penetrating keratoplasties ( n  = 5). Both cell cultures underwent RB-PDT (0.001% RB concentration, 0.17 J/cm 2 fluence) and 24 h later collagen I, collagen V, NF-κB, LOX, TGF-β1 and IL-6 mRNA and protein expression have been determined using qPCR and Western blot, IL-6 concentration in the cell culture supernatant by ELISA., Results: TGF-β1 mRNA expression was significantly lower ( p  = 0.02) and IL-6 mRNA expression was significantly higher in RB-PDT treated HCFs ( p  = 0.01), than in HCF controls. COL1A1, COL5A1 and TGF-β1 mRNA expression was significantly lower ( p  = 0.04; p  = 0.02 and p  = 0.003) and IL-6 mRNA expression was significantly higher ( p  = 0.02) in treated KC-HCFs, than in KC-HCF controls. TGF-β1 protein expression in treated HCFs was significantly higher than in HCF controls ( p  = 0.04). IL-6 protein concentration in the HCF and KC-HCF culture supernatant after RB-PDT was significantly higher than in controls ( p  = 0.02; p  = 0.01). No other analyzed mRNA and protein expression differed significantly between the RB-PDT treated and untreated groups., Conclusions: Our study demonstrates that RB-PDT reduces collagen I, collagen V and TGF-β1 mRNA expression, while increasing IL-6 mRNA and protein expression in KC-HCFs. In HCFs, RB-PDT increases TGF-β1 and IL-6 protein level after 24 h.

Emerging evidence has validated that extracellular vesicles (EVs) regulate hepatocellular carcinoma (HCC) progression, while its role in HCC immune escape remains to be elucidated. This study investigates the role of EVs-encapsulated lysyl oxidase like-4 (LOXL4) derived from tumor cells in HCC immune escape. HCC-related microarray data sets GSE36376 and GSE87630 were obtained for differential analysis, followed by identifying the essential genes related to the prognosis of HCC patients. Bone marrow-derived macrophages were treated with EVs derived from mouse Hepa 1-6 cells and cocultured with CD8 + T cells to observe the CD8 + T-cell activity. At last, a mouse HCC orthotopic xenograft model was constructed to verify the effects of HCC cell-derived EVs on the immune escape of HCC cells and tumorigenicity in vivo by delivering LOXL4. It was found that ACAT1, C4BPA, EHHADH, and LOXL4 may be the essential genes related to the prognosis of HCC patients. On the basis of the TIMER database, there was a close correlation between LOXL4 and macrophage infiltration in HCC. Besides, STAT1 was closely related to LOXL4. In vitro experiments demonstrated that LOXL4 could induce programmed death-ligand 1 expression in macrophages and immunosuppression by activating STAT1. In vivo experiments also verified that HCC cell-derived EVs promoted the immune escape of HCC cells and tumorigenicity by delivering LOXL4. LOXL4 was delivered into macrophages via EVs to induce programmed death-ligand 1 by activating STAT1 and inhibiting the killing ability of CD8 + T cells to HCC cells, thus promoting immune escape in HCC., (Copyright © 2023 Wolters Kluwer Health, Inc. All rights reserved.)

The altered behaviors and functions of pelvic floor fibroblasts are pathophysiological changes of pelvic organ prolapse (POP). Our previous study showed that advanced glycated end products (AGEs) accumulated in the pelvic tissues of POP and induced fibroblast apoptosis. The study was designed to investigate whether quercetin antagonize AGEs-induced apoptosis and functional inhibition of fibroblasts. The uptake of 5-ethynyl-2'-deoxyuridine (EdU) was evaluated for cell proliferation. Flow cytometric analysis was applied for cell apoptosis. Intracellular reactive oxygen species (ROS) content was determined by the fluorescence of dichlorofluorescein (DCF). The contractility of fibroblasts was measured by collagen gel contraction assay. The expressions of extracellular matrix (ECM) related genes and the expression of miR-4429 and caspase-3 were quantified by qPCR. The expressions of phosphatase and tensin homolog (PTEN), phosphoinositide 3-kinase (PI3K), serine-threonine kinase (Akt), and phosphorylated Akt (p-Akt) were analyzed by Western Blot. The down-regulation of miR-4429 was achieved by cell transfection. Quercetin antagonized AGEs-induced apoptosis, proliferation inhibition, and ROS increase in fibroblasts. Quercetin did not alleviate AGEs-induced contractile impairment of fibroblasts. Quercetin reduced the gene expressions of lysyl oxidase like protein 1 (LOXL1)and matrix metallopeptidase 1 (MMP1), and increased the gene expressions of lysyl oxidase (LOX) and fibrillin 2 (FBN2) in fibroblasts. Quercetin reversed AGEs-induced upregulation of PTEN and downregulation of PI3K, P-Akt, and miR-4429 in fibroblasts. The inhibitory effect of quercetin on AGEs-induced fibroblast apoptosis was inhibited by downregulating the expression of miR-4429. In conclusion, quercetin antagonized AGEs-induced apoptosis and functional inhibition of fibroblasts from the prolapsed uterosacral ligament. And inhibiting AGEs-induced down-regulation of miR-4429/PTEN/PI3K/Akt pathway was the mechanism underlying the antagonistic effect of quercetin on AGEs-induced apoptosis.

Background & Aims: Epithelial disruption in eosinophilic esophagitis (EoE) encompasses both impaired differentiation and diminished barrier integrity. We have shown that lysyl oxidase (LOX), a collagen cross-linking enzyme, is up-regulated in the esophageal epithelium in EoE. However, the functional roles of LOX in the esophageal epithelium remains unknown., Methods: We investigated roles for LOX in the human esophageal epithelium using 3-dimensional organoid and air-liquid interface cultures stimulated with interleukin (IL)13 to recapitulate the EoE inflammatory milieu, followed by single-cell RNA sequencing, quantitative reverse-transcription polymerase chain reaction, Western blot, histology, and functional analyses of barrier integrity., Results: Single-cell RNA sequencing analysis on patient-derived organoids revealed that LOX was induced by IL13 in differentiated cells. LOX-overexpressing organoids showed suppressed basal and up-regulated differentiation markers. In addition, LOX overexpression enhanced junctional protein genes and transepithelial electrical resistance. LOX overexpression restored the impaired differentiation and barrier function, including in the setting of IL13 stimulation. Transcriptome analyses on LOX-overexpressing organoids identified an enriched bone morphogenetic protein (BMP) signaling pathway compared with wild-type organoids. In particular, LOX overexpression increased BMP2 and decreased the BMP antagonist follistatin. Finally, we found that BMP2 treatment restored the balance of basal and differentiated cells., Conclusions: Our data support a model whereby LOX exhibits noncanonical roles as a signaling molecule important for epithelial homeostasis in the setting of inflammation via activation of the BMP pathway in the esophagus. The LOX/BMP axis may be integral in esophageal epithelial differentiation and a promising target for future therapies., (Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.)

The lysyl oxidase (LOX) gene family encodes for a group of copper-dependent enzymes that play a crucial role in the cross-linking of collagen and elastin fibers in the extracellular matrix (ECM). Dysregulation of LOX gene expression has been implicated in various pathological conditions, including cancer. Several studies have shown that the LOX gene family is involved in cancer progression and metastasis. The goal of this article is to conduct a comprehensive analysis of the LOX family's role in pan-cancer multiplexes. We utilized pan-cancer multi-omics sequencing data from TCGA to investigate the relationship between LOX family genes and tumors at four different levels: mutation, copy number variation, methylation, and gene expression. In addition, we also examined the relationship between LOX family genes and tumors at the cell line level using tumor cell line sequencing data from CCLE. Taking into account the impact of LOX family genes on lung cancer, we developed a LOX family lung cancer prognostic model to forecast the disease's prognosis. Our findings revealed that LOXL2 had the highest mutation frequency in tumors, while all four LOX family genes experienced some degree of copy number variation in diverse tumors. We observed that LOX, LOXL1 to LOXL3 were predominantly highly expressed in tumors including LUAD. The expression trends of LOX and LOXL1 to LOXL3 were consistent across tumor cell lines, but differed somewhat from LOXL4. Utilizing 25 LOX family-related genes, we constructed a LOX family prognostic model that performed well in predicting the prognosis of lung cancer. Through pan-cancer analysis, we gain further knowledge of the role of LOX family genes in different tumors, offering a novel pathway for future research into the relationship between LOX family genes and tumors.

Introduction: Myocardial fibrosis and cardiac dysfunction are the main characteristics of diabetic heart disease. However, the molecular mechanisms underlying diabetic myocardial fibrosis remain unclear., Objectives: This study aimed to investigate the heterogeneity of cardiac fibroblasts in diabetic mice and its possible mechanism in the development of diabetic myocardial fibrosis., Methods: We established a diabetic mouse model by injecting mice with streptozotocin. The overall cell profiles in diabetic hearts were analyzed using single-cell RNA transcriptomic techniques. Cardiac function was evaluated by echocardiography. Cardiac fibrosis was assessed by Masson's trichrome and Sirius red staining. Protein expression was analyzed using Western blotting and immunofluorescence staining., Results: A total of 11,585 cells were captured in control (Ctrl) and diabetic (DM) hearts. Twelve cell types were identified in this study. The number of fibroblasts was significantly higher in the DM hearts than in the Ctrl group. The fibroblasts were further re-clustered into nine subsets. Interestingly, cluster 4 fibroblasts were significantly increased in diabetic hearts compared with other fibroblast clusters. Lysyl oxidase (Lox) was highly expressed in DM fibroblasts (especially in cluster 4). Beta-aminopropionitrile, a Lox inhibitor, inhibited collagen expression and alleviated cardiac dysfunction in the diabetic group. Lysyl oxidase inhibition also reduced high glucose-induced collagen protein upregulation in primary fibroblasts. Moreover, a TGF-β receptor inhibitor not only prevented an increase in Lox and Col I but also inhibited the phosphorylation of Smad2/3 in fibroblasts., Conclusions: This study revealed the heterogeneity of cardiac fibroblasts in diabetic mice for the first time. Fibroblasts with high expression of Lox (cluster 4 fibroblasts) were identified to play a crucial role in fibrosis in diabetic heart disease. The findings of this study may provide a possible therapeutic target for interstitial fibrosis., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023. Production and hosting by Elsevier B.V.)

Background: Bone morphogenetic protein 9 (BMP9) is a promising growth factor in bone tissue engineering, while the detailed molecular mechanism underlying BMP9-oriented osteogenesis remains unclear. In this study, we investigated the effect of lysyl oxidase (Lox) on the BMP9 osteogenic potential via in vivo and in vitro experiments, as well as the underlying mechanism., Methods: PCR assay, western blot analysis, histochemical staining, and immunofluorescence assay were used to quantify the osteogenic markers level, as well as the possible mechanism. The mouse ectopic osteogenesis assay was used to assess the impact of Lox on BMP9-induced bone formation., Results: Our findings suggested that Lox was obviously upregulated by BMP9 in 3T3-L1 cells. BMP9-induced Runx2, OPN, and mineralization were all enhanced by Lox inhibition or knockdown, while Lox overexpression reduced their expression. Additionally, the BMP9-induced adipogenic makers were repressed by Lox inhibition. Inhibition of Lox resulted in an increase in c-Myc mRNA and β-catenin protein levels. However, the increase in BMP9-induced osteoblastic biomarkers caused by Lox inhibition was obviously reduced when β-catenin knockdown. BMP9 upregulated HIF-1α expression, which was further enhanced by Lox inhibition or knockdown, but reversed by Lox overexpression. Lox knockdown or HIF-1α overexpression increased BMP9-induced bone formation, although the enhancement caused by Lox knockdown was largely diminished when HIF-1α was knocked down. Lox inhibition increased β-catenin levels and decreased SOST levels, which were almost reversed by HIF-1α knockdown., Conclusion: Lox may reduce the BMP9 osteoblastic potential by inhibiting Wnt/β-catenin signaling via repressing the expression HIF-1α partially., (© 2023. The Author(s).)

Introduction: The flavonoid-rich fraction of Rosa damascena (FRFRD) contains antioxidant and active compounds. Therefore, this study aimed to investigate the role of FRFRD, rich in quercetin and kaempferol, in liver fibrosis induced by CCl4., Materials and Methods: The FRFRD fraction was separated and standardized by High-Performance Liquid Chromatography (HPLC) based on the levels of quercetin and kaempferol. Liver fibrosis was induced over CCl4 over 12 weeks in 30 male Wistar rats, and three concentrations of FRFRD were administered to them during the last four weeks. Subsequently, after evaluation of liver serum markers and fibrotic parameters, the relative expression of transforming growth factor-beta-1 (TGF-β 1 ), platelet-derived growth factor (PDGF), and lysyl oxidase homolog 2 (Loxl2) genes were assessed, along with the measurement of lysyl oxidase activity and oxidative markers., Results: Fibrotic markers demonstrated progressive recovery of liver damage in the treated group compared to the non-treatment group (p < 0.01). These results were accompanied by a significant decrease in the expression of TGF-β 1 , PDGF, and Loxl2 genes, as well as, a reduction in lysyl oxidase activity (p < 0.001). The antioxidant effects of the treatment were observed through a significant decrease in malondialdehyde (MDA) levels and an increase in catalase enzyme (CAT) and glutathione peroxidase (GPx) activity in the treatment group compared to the fibrotic group (p < 0.01)., Conclusion: The flavonoid-rich fraction of Rosa damascena ameliorates liver damage by affecting collagen cross-linking and lowering oxidative and inflammatory levels., Competing Interests: Declaration of competing interest The authors declare that there are no conflicts of interest, (Copyright © 2023. Published by Elsevier Inc.)

The commitment of mesenchymal stem cells (MSCs) to preadipocytes and the termination of differentiation to adipocytes are critical for maintaining systemic energy homeostasis. However, our knowledge of the molecular mechanisms governing the commitment of MSCs to preadipocytes and the subsequent termination of their differentiation into adipocytes remain limited. Additionally, the role of Sox6 sex-determining region Y (SRY)-box6 (Sox6), a transcription factor that regulates gene transcription, is reportedly involved in various cellular processes, including adipogenesis; however, its function in regulating preadipocyte development and the factors involved in the termination of adipogenic differentiation remain unexplored. Therefore, we investigated the role of Sox6 in regulating the differentiation of adipocytes by monitoring the effects of its overexpression in C3H10T1/2 cells (in vitro) and C57BL/6J mouse (in vivo) models of adipogenesis. We observed lower Sox6 expression in the adipose tissue of obese mice than that in control mice. Sox6 overexpression inhibited the differentiation of MSC by directly binding to the lysyl oxidase (Lox) and preadipocyte factor 1 (Pref1) promoters, which was potentiated by histone deacetylase-1(HDAC1). Our findings suggest that Sox6 is a key regulator of MSC commitment to adipocytes; therefore, targeting the Sox6-mediated regulation of this process could offer potential therapeutic avenues for addressing obesity and related metabolic disorders., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier Inc. All rights reserved.)

Lysyl oxidase-like 4 (LOXL4), a member of lysyl oxidase family, is a copper and lysine tyrosylquinone-dependent amine oxidase that serves the role of catalyzing the cross-linking of elastin and collagen in the extracellular matrix. Numerous studies have shown a significant association between LOXL4 expression levels and tumor proliferation, migration, invasion and patients' prognosis and overall survival in different types of tumors. Here we review their relationship and the molecular pathogenesis behind them, aiming to explore the possibilities of LOXL4 as a prognostic marker for diverse carcinomas and provide some indications for further research in this field., (© 2023. The Author(s), under exclusive licence to Springer-Verlag GmbH Austria, part of Springer Nature.)

Abstract: We investigated the clinical characteristics of patients with acute aortic dissection (AAD) and miR-590-3p levels in serum, tissue, and vascular smooth muscle cells. The effect of miR-590-3p on the vascular smooth muscle cell phenotype was assessed, and the regulation of lysyl oxidase by miR-5903p was determined. C57BL/6 mice were used to investigate the incidence of AAD and effects of miR-5903p on AAD. The miR-590-3p levels were measured in the aortae of mice, and hematoxylin and eosin staining and Masson staining were performed to identify the morphological features of the aorta. Comparative analysis revealed significant differences in clinical characteristics between patients with AAD and healthy control subjects, with most patients with AAD exhibiting concomitant hypertension and nearly 50% having atherosclerosis. Lysyl oxidase was a direct target of miR-590-3p. Lysyl oxidase overexpression inhibited switching of the vascular smooth muscle cell phenotype from contractile to synthetic, but miR-590-3p overexpression significantly reversed this change. In the mouse model, miR-590-3p upregulation increased the incidence of AAD to 93.3%, and its incidence decreased to 13.3% after miR-590-3p inhibition. Hematoxylin and eosin and Masson staining revealed that the miR-590-3p agomiR group had a greater loss of the contractile phenotype in the dissected aortic wall and an increased number of muscle fibers in the aortic wall, which contributed to thickening of the aortic wall and the formation of a false lumen in aortic dissection. miR-590-3p might be pivotal in the pathogenesis of AAD. Thus, targeting miR-590-3p or its downstream pathways could represent a therapeutic approach for AAD., Competing Interests: The authors report no conflicts of interest., (Copyright © 2023 Wolters Kluwer Health, Inc. All rights reserved.)

Lysyl oxidase (LOX) plays an important role in the elaboration of tendon mechanical properties during embryonic development by mediating enzymatic collagen crosslinking. We previously showed recombinant LOX (rLOX) treatment of developing tendon significantly increased LOX-mediated collagen crosslink density to enhance tendon mechanical properties at different stages of tissue formation. Working toward the future development of rLOX-based therapeutic strategies to enhance mechanical properties of tendons that are compromised, such as after injury or due to abnormal development, this study characterized the direct effects of rLOX treatment on embryonic tendon cells from different stages of tissue formation. Tendon cell morphology, proliferation rate, proliferative capacity, and metabolic activity were not affected by rLOX treatment. Tenogenic phenotype was stable with rLOX treatment, reflected by no change in cell morphology or tendon marker messenger RNA (mRNA) levels assessed by reverse-transcription polymerase chain reaction. Collagen mRNA levels also remained constant. Matrix metalloproteinase-9 expression levels were downregulated in later stage tendon cells, but not in earlier stage cells, whereas enzyme activity levels were undetected. Bone morphogenetic protein-1 (BMP-1) expression was upregulated in earlier stage tendon cells, but not in later stage cells. Furthermore, BMP-1 activity was unchanged when intracellular LOX enzyme activity levels were upregulated in both stage cells, suggesting exogenous rLOX may have entered the cells. Based on our data, rLOX treatment had minimal effects on tendon cell phenotype and behaviors. These findings will inform future development of LOX-focused treatments to enhance tendon mechanical properties without adverse effects on tendon cell phenotype and behaviors., (© 2023 The Authors. Journal of Orthopaedic Research® published by Wiley Periodicals LLC on behalf of Orthopaedic Research Society.)

Purpose: Retinoblastoma (RB) caused by the mutation of the RB1 gene is one of the most common ocular malignancies in children The propeptide region of lysyl oxidase (LOX), the enzyme involved in the cross-linking of collagen and elastin, has been identified to be anti-tumorigenic in various cancers. However, this role of lysyl oxidase propeptide (LOX-PP) in RB is still elusive. This study aims to identify the anti-tumorigenic effect of LOX-PP in human Y79 RB cells., Methods: LOX-PP was overexpressed in Y79 RB cells, and differential gene expression was assessed by microarray followed by pathway analysis using transcriptome analysis console (TAC) software. Additionally, cell proliferation was studied by PrestoBlue assay, and DNA content was evaluated by cell cycle and apoptosis assays. The pro-apoptotic and anti-proliferative mechanisms induced by the overexpression of/exogenously added LOX-PP was evaluated by western blotting and real-time PCR., Results: The expression of the LOX-PP transcript was significantly decreased in Y79 RB cells compared to human retinal endothelial cells. Gene expression analysis in LOX-PP overexpressed Y79 RB cells showed deregulation of pathways involved in apoptosis, cell cycle, focal adhesion-PI3K-AKT signaling, and DNA repair mechanisms. Interestingly, LOX-PP overexpressed Y79 RB cells showed significantly increased apoptosis, decreased proliferation, and cell cycle arrest at S-phase with a concordant reduction of proliferative cell nuclear antigen and Cyclin D1 protein expressions. Moreover, pAKT (S473) was significantly downregulated in Y79 RB cells, which decreased NFκB leading to significantly reduced BCL2 expression., Conclusions: Our results demonstrate the anti-tumorigenic effect of LOX-PP in Y79 RB cells by inducing apoptosis and decreasing proliferation. This effect was mediated by the downregulation of AKT signaling. These results suggest that LOX-PP can be explored as a therapeutic molecule in RB., (Copyright © 2023 Molecular Vision.)

Carcinoma-associated fibroblasts (CAFs) are the main cellular components of the tumor microenvironment and promote cancer progression by modifying the extracellular matrix (ECM). The tumor-associated ECM is characterized by collagen crosslinking catalyzed by lysyl oxidase (LOX). Small extracellular vesicles (sEVs) mediate cell-cell communication. However, the interactions between sEVs and the ECM remain unclear. Here, we demonstrated that sEVs released from oral squamous cell carcinoma (OSCC)-derived CAFs induce collagen crosslinking, thereby promoting epithelial-mesenchymal transition (EMT). CAF sEVs preferably bound to the ECM rather than being taken up by fibroblasts and induced collagen crosslinking, and a LOX inhibitor or blocking antibody suppressed this effect. Active LOX (αLOX), but not the LOX precursor, was enriched in CAF sEVs and interacted with periostin, fibronectin, and bone morphogenetic protein-1 on the surface of sEVs. CAF sEV-associated integrin α2β1 mediated the binding of CAF sEVs to collagen I, and blocking integrin α2β1 inhibited collagen crosslinking by interfering with CAF sEV binding to collagen I. CAF sEV-induced collagen crosslinking promoted the EMT of OSCC through FAK/paxillin/YAP pathway. Taken together, these findings reveal a novel role of CAF sEVs in tumor ECM remodeling, suggesting a critical mechanism for CAF-induced EMT of cancer cells., (© 2023. The Author(s).)

Objective: Esophageal squamous cell carcinoma (ESCC) is a common and aggressive malignancy of the gastrointestinal tract for which therapeutic options are scarce. This study screens for LOXL2, a key gene in ESCC, and explains the molecular mechanism by which it promotes the progression of ESCC., Methods: Immunohistochemical staining was performed to detect the expression level of LOXL2 in ESCC tissues and paraneoplastic tissues. CCK-8 and Transwell assays were performed to assess the effects of LOXL2 knockdown and overexpression on the proliferation, apoptosis, migration and invasion ability of ESCC cells. High-throughput sequencing analysis screens for molecular mechanisms of action by which LOXL2 promotes ESCC progression. Western blotting and qRT-PCR were used to determine the expression levels of relevant markers., Results: LOXL2 is positively expressed in ESCC and highly correlated with poor prognosis. Silencing LOXL2 significantly inhibited the proliferation, migration and invasive ability of ESCC cells, whereas overexpression showed the opposite phenotype. High-throughput sequencing suggested that LOXL2-associated differentially expressed genes were highly enriched in the PI3K/AKT signaling pathway. In vitro cellular assays confirmed that silencing LOXL2 significantly reduced PI3K, p-AKT Thr308 and p-AKT Ser473 gene and protein expression levels, while overexpression increased all three gene and protein levels, while AKT gene and protein expression levels were not significantly different., Conclusion: This study found that LOXL2 may regulate the PI3K/AKT signaling pathway and exert protumor effects on ESCC cells through phosphorylation of AKT. LOXL2 may be a key clinical warning biomarker or therapeutic target for ESCC., (© 2023. The Author(s).)

Pulmonary fibrosis (PF) associated with systemic sclerosis (SSc) results in significant morbidity and mortality. We previously reported that insulin-like growth factor-II (IGF-II) is overexpressed in lung tissues and fibroblasts from SSc patients, and IGF-II fosters fibrosis by upregulating collagen type I, fibronectin, and TGFβ. We now show that IGF-II augments mRNA levels of profibrotic signaling molecules TGFβ2 ( p ≤ 0.01) and TGFβ3 ( p ≤ 0.05), collagen type III ( p ≤ 0.01), and the collagen posttranslational modification enzymes P4HA2 ( p ≤ 0.05), P3H2 ( p ≤ 0.05), LOX ( p = 0.065), LOXL2 ( p ≤ 0.05), LOXL4 ( p ≤ 0.05) in primary human lung fibroblasts. IGF-II increases protein levels of TGFβ2 ( p ≤ 0.01), as well as COL3A1, P4HA2, P4Hβ, and LOXL4 ( p ≤ 0.05). In contrast, IGF-II decreases mRNA levels of the collagen degradation enzymes cathepsin (CTS) K, CTSB , and CTSL and protein levels of CTSK ( p ≤ 0.05). The SRY-box transcription factor 9 (SOX9) is overexpressed in SSc lung tissues at the mRNA ( p ≤ 0.05) and protein ( p ≤ 0.01) levels compared to healthy controls. IGF-II induces SOX9 in lung fibroblasts ( p ≤ 0.05) via the IGF1R/IR hybrid receptor, and SOX9 regulates TGFβ2 ( p ≤ 0.05), TGFβ3 ( p ≤ 0.05), COL3A1 ( p ≤ 0.01), and P4HA2 ( p ≤ 0.001) downstream of IGF-II. Our results identify a novel IGF-II signaling axis and downstream targets that are regulated in a SOX9-dependent and -independent manner. Our findings provide novel insights on the role of IGF-II in promoting pulmonary fibrosis.

Noninvasive imaging of idiopathic pulmonary fibrosis (IPF) remains a challenge. The aim of this study was to develop an antibody-based radiotracer targeting Lysyl Oxidase-like 2 (LOXL2), an enzyme involved in the fibrogenesis process, for SPECT/CT imaging of pulmonary fibrosis. The bifunctional chelator DOTAGA-PEG 4 -NH 2 was chemoenzymatically conjugated to the murine antibody AB0023 using microbial transglutaminase, resulting in a degree of labeling (number of chelators per antibody) of 2.3. Biolayer interferometry confirmed that the binding affinity of DOTAGA-AB0023 to LOXL2 was preserved with a dissociation constant of 2.45 ± 0.04 nM. DOTAGA-AB0023 was then labeled with 111 In and in vivo experiments were carried out in a mice model of progressive pulmonary fibrosis induced by intratracheal administration of bleomycin. [ 111 In]In-DOTAGA-AB0023 was injected in three groups of mice (control, fibrotic, and treated with nintedanib). SPECT/CT images were recorded over 4 days p.i. and an ex vivo biodistribution study was performed by gamma counting. A significant accumulation of the tracer in the lungs of the fibrotic mice was observed at D18 post-bleomycin. Interestingly, the tracer uptake was found selectively upregulated in fibrotic lesions observed on CT scans. Images of mice that received the antifibrotic drug nintedanib from D8 up to D18 showed a decrease in [ 111 In]In-DOTAGA-AB0023 lung uptake associated with a decrease in pulmonary fibrosis measured by CT scan. In conclusion, we report the first radioimmunotracer targeting the protein LOXL2 for nuclear imaging of IPF. The tracer showed promising results in a preclinical model of bleomycin-induced pulmonary fibrosis, with high lung uptake in fibrotic areas, and accounted for the antifibrotic activity of nintedanib.

Collagen, the most abundant structural protein found in mammals, plays a vital role as a constituent of the extracellular matrix (ECM) that surrounds cells. Collagen fibrils are strengthened through the formation of covalent cross-links, which involve complex enzymatic and non-enzymatic reactions. Lysyl oxidase (LOX) is responsible for catalyzing the oxidative deamination of lysine and hydroxylysine residues, resulting in the production of aldehydes, allysine, and hydroxyallysine. These intermediates undergo spontaneous condensation reactions, leading to the formation of immature cross-links, which are the initial step in the development of mature covalent cross-links. Additionally, non-enzymatic glycation contributes to the formation of abnormal cross-linking in collagen fibrils. During glycation, specific lysine and arginine residues in collagen are modified by reducing sugars, leading to the creation of Advanced Glycation End-products (AGEs). These AGEs have been associated with changes in the mechanical properties of collagen fibers. Interestingly, various studies have reported that plant polyphenols possess amine oxidase-like activity and can act as potent inhibitors of protein glycation. This review article focuses on compiling the literature describing polyphenols with amine oxidase-like activity and antiglycation properties. Specifically, we explore the molecular mechanisms by which specific flavonoids impact or protect the normal collagen cross-linking process. Furthermore, we discuss how these dual activities can be harnessed to generate properly cross-linked collagen molecules, thereby promoting the stabilization of highly organized collagen fibrils.

Endothelial cell (EC) activation is a crucial determinant of retinal vascular inflammation associated with diabetic retinopathy (DR), a major microvascular complication of diabetes. We previously showed that, similar to abnormal biochemical factors, aberrant mechanical cues in the form of lysyl oxidase (LOX)-dependent subendothelial matrix stiffening also contribute significantly to retinal EC activation in diabetes. Yet, how LOX is itself regulated and precisely how it mechanically controls retinal EC activation in diabetes is poorly understood. Here, we show that high-glucose-induced LOX upregulation in human retinal ECs (HRECs) is mediated by proinflammatory receptor for advanced glycation end products (RAGE). HRECs treated with methylglyoxal (MGO), an active precursor to the advanced glycation end product (AGE) MG-H1, exhibited LOX upregulation that was blocked by a RAGE inhibitor, thus confirming the ability of RAGE to promote LOX expression. Crucially, as a downstream effector of RAGE, LOX was found to mediate both the proinflammatory and matrix remodeling effects of AGE/RAGE, primarily through its ability to crosslink or stiffen matrix. Finally, using decellularized HREC-derived matrices and a mouse model of diabetes, we demonstrate that LOX-dependent matrix stiffening feeds back to enhance RAGE, thereby achieving its autoregulation and proinflammatory effects. Collectively, these findings provide fresh mechanistic insights into the regulation and proinflammatory role of LOX-dependent mechanical cues in diabetes while simultaneously implicating LOX as an alternative (downstream) target to block AGE/RAGE signaling in DR., Article Highlights: We investigated the regulation and proinflammatory role of retinal endothelial lysyl oxidase (LOX) in diabetes. Findings reveal that LOX is upregulated by advanced glycation end products (AGE) and receptor for AGE (RAGE) and mediates AGE/RAGE-induced retinal endothelial cell activation and subendothelial matrix remodeling. We also show that LOX-dependent subendothelial matrix stiffening feeds back to enhance retinal endothelial RAGE. These findings implicate LOX as a key proinflammatory factor and an alternative (downstream) target to block AGE/RAGE signaling in diabetic retinopathy., (© 2023 by the American Diabetes Association.)

Pathological cartilage calcification is a hallmark feature of osteoarthritis, a common degenerative joint disease, characterized by cartilage damage, progressively causing pain and loss of movement. The integrin subunit CD11b was shown to play a protective role against cartilage calcification in a mouse model of surgery-induced OA. Here, we investigated the possible mechanism by which CD11b deficiency could favor cartilage calcification by using naïve mice. First, we found by transmission electron microscopy (TEM) that CD11b KO cartilage from young mice presented early calcification spots compared with WT. CD11b KO cartilage from old mice showed progression of calcification areas. Mechanistically, we found more calcification-competent matrix vesicles and more apoptosis in both cartilage and chondrocytes isolated from CD11b-deficient mice. Additionally, the extracellular matrix from cartilage lacking the integrin was dysregulated with increased collagen fibrils with smaller diameters. Moreover, we revealed by TEM that CD11b KO cartilage had increased expression of lysyl oxidase (LOX), the enzyme that catalyzes matrix crosslinks. We confirmed this in murine primary CD11b KO chondrocytes, where Lox gene expression and crosslinking activity were increased. Overall, our results suggest that CD11b integrin regulates cartilage calcification through reduced MV release, apoptosis, LOX activity, and matrix crosslinking. As such, CD11b activation might be a key pathway for maintaining cartilage integrity.