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Targeting cellular senescence and Senescence Associated Secretory Phenotype (SASP) through autophagy has emerged as a promising intervertebral disc (IVD) degeneration (IDD) treatment strategy in recent years. This study aimed to clarify the role and mechanism of autophagy in preventing IVD SASP. Methods involved in vitro experiments with nucleus pulposus (NP) tissues from normal and IDD patients, as well as an in vivo IDD animal model. GATA4's regulatory role in SASP was validated both in vitro and in vivo, while autophagy modulators were employed to assess their impact on GATA4 and SASP. Transcriptomic sequencing identified Oxidized low-density lipoprotein receptor 1 (OLR1) as a key regulator of autophagy and GATA4. A series of experiments manipulated OLR1 expression to investigate associated effects. Results demonstrated significantly increased senescent NP cells (NPCs) and compromised autophagy in IDD patients and animal models, with SASP closely linked to IDD progression. The aged disc milieu impeded autophagic GATA4 degradation, leading to elevated SASP expression in senescent NPCs. Restoring autophagy reversed senescence by degrading GATA4, hence disrupting the SASP cascade. Moreover, OLR1 was identified for its regulation of autophagy and GATA4 in senescent NPCs. Silencing OLR1 enhanced autophagic activity, suppressing GATA4-induced senescence and SASP expression in senescent NPCs. In conclusion, OLR1 was found to control autophagy-GATA4 and SASP, with targeted OLR1 inhibition holding promise in alleviating GATA4-induced senescence and SASP expression while delaying extracellular matrix degradation, offering a novel therapeutic approach for IDD management., (© The Author(s) 2024. Published by Oxford University Press on behalf of The Gerontological Society of America. All rights reserved. For commercial re-use, please contact reprints@oup.com for reprints and translation rights for reprints. All other permissions can be obtained through our RightsLink service via the Permissions link on the article page on our site—for further information please contact journals.permissions@oup.com.)

Background: Cellular senescence features irreversible growth arrest and secretion of multiple proinflammatory cytokines. Cyclic GMP-AMP synthase (cGAS) detects DNA damage and activates the DNA-sensing pathway, resulting in the upregulation of inflammatory genes and induction of cellular senescence. This study aimed to investigate the effect of cGAS in regulating senescence of nucleus pulposus (NP) cells under inflammatory microenvironment., Methods: The expression of cGAS was evaluated by immunohistochemical staining in rat intervertebral disc (IVD) degeneration model induced by annulus stabbing. NP cells were harvested from rat lumbar IVD and cultured with 10ng/ml IL-1β for 48 h to induce premature senescence. cGAS was silenced by cGAS specific siRNA in NP cells and cultured with IL-1β. Cellular senescence was evaluated by senescence-associated beta-galactosidase (SA-β-gal) staining and flow cytometry. The expression of senescence-associated secretory phenotype including IL-6, IL-8, and TNF-a was evaluated by ELISA and western blotting., Results: cGAS was detected in rat NP cells in cytoplasm and the expression was significantly increased in degenerated IVD. Culturing in 10ng/ml IL-1β for 48 h induced cellular senescence in NP cells with attenuation of G1-S phase transition. In senescent NP cells the expression of cGAS, p53, p16, NF-kB, IL-6, IL-8, TNF-α was significantly increased while aggrecan and collagen type II was reduced than in normal NP cells. In NP cells with silenced cGAS, the expression of p53, p16, NF-kB, IL-6, IL-8, and TNF-α was reduced in inflammatory culturing with IL-1β., Conclusion: cGAS was increased by NP cells in degenerated IVD promoting cellular senescence and senescent inflammatory phenotypes. Targeting cGAS may alleviate IVD degeneration by reducing NP cell senescence., (© 2024. The Author(s).)

A Gram-stain-negative bacterium with a rod-to-ovoid shape, named strain M216 T , was isolated from sand sediment from the coastal intertidal zone of Huludao, Liaoning Province, China. Growth was observed at 8-40 °C (optimal, 30 °C), pH 5.5-9.5 (optimal, pH 6.5) and 0.5-14.0% (w/v) NaCl (optimal, 6%). Strain M216 T possessed ubiquinone-9 as its sole respiratory quinone and phosphatidylethanolamine, diphosphatidylglycerol, phosphatidylglycerol, one unidentified aminophosphoglycolipid, one unidentified aminophospholipid, two unidentified phosphoglycolipids, three unidentified phospholipids and three unidentified glycolipids as the main polar lipids. C 12:0 , C 16:0 , C 12:0 3-OH, C 16:1 ω9c, C 18:1 ω9c and summed features 3 (C 16:1 ω7c and/or C 16:1 ω6c) were the major fatty acids (> 5%). The 16S rRNA gene sequence of strain M216 T exhibited high similarity to those of 'Marinobacter arenosus' CAU 1620 T and Marinobacter adhaerens HP15 T (99.3% and 98.5%, respectively) and less than 98.5% similarity to those of the other type strains. The ANI and dDDH values between the strain M216 T and 'Marinobacter arenosus' CAU 1620 T were 87.4% and 33.3%, respectively; these values were the highest among the other type strains but lower than the species threshold. The G+C content of strain M216 T was 58.3%. Genomic analysis revealed that strain M216 T harbors the major CAZymes of GH13, GH23, GH73, and PL5, which are responsible for polysaccharide degradation and the potential ability to reduce nitrate to ammonia. Through phenotypic, genotypic, and chemotaxonomic analyses, we proposed the name Marinobacter albus sp. nov., a novel species in the genus Marinobacter, with its type strain M216 T (= MCCC 1K08600 T  = KCTC 82894 T )., (© 2024. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)

A Gram-stain-negative, aerobic, motile with flagella and rod- or ovoid-shaped bacterium, designated GG15 T , was isolated from tidal flat sediment sampled in Zhoushan, Zhejiang Province. Strain GG15 T grew at 20-40 °C (optimum, 30 °C), at pH 5.5-9.5 (optimum, pH 7.0-8.0) and with 1.0-10.0 % (w/v) NaCl (optimum, 1.5 %). Colony diameters ranged from 1 to 3 mm within the first week, reaching a maximum of 6-7 mm after 15 days of cultivation. Strain GG15 T exhibited highest 16S rRNA gene sequence similarity to Microbulbifer taiwanensis CCM 7856 T (98.1 %), with similarity to other species within the genus Microbulbifer ranging from 97.8 to 93.8 %. Similarity values to other genera were below 93.8 %. Strain GG15 T exhibited positive activity for β -glucosidase, trypsin and chymotrypsin, whereas the reference strain showed negative activity. Chemotaxonomic analyses indicated that strain GG15 T contained Q-8 as the sole respiratory quinone, C 16 : 0 (9.1 %), iso-C 15 : 0 (30.9 %) and iso-C 11 : 0 3-OH (7.2 %) as the predominant fatty acids, and phosphatidylethanolamine, phosphatidylglycerol, three unidentified lipids, four unidentified glycolipids, one unidentified phospholipid, two unidentified aminolipids and two unidentified aminophospholipids as the main polar lipids. The genome of strain GG15 T was 4 307 641 bp long, comprising 3861 protein-coding genes. The G+C content of strain GG15 T was 61.5 mol% based on its genomic sequence. Strain GG15 T showed low digital DNA-DNA hybridization (<70 %) and average nucleotide identity values (<95 %) with other Microbulbifer species. As a result, a novel species within the genus Microbulbifer , named Microbulbifer magnicolonia sp. nov., is proposed. The type strain is GG15 T (MCCC 1K08802 T =KCTC 8210 T ).

Aestuariibaculum lutulentum L182 T (= KCTC 92530 T  = MCCC 1K08065 T ) was isolated from the tidal sediment collected in Beihai, People's Republic of China. The genome was sequenced and consisted of a single chromosome with the size of 3,782,725 bp and DNA G + C content of 35.1%. Genomic annotations demonstrated that it encoded 12 rRNA genes, 56 tRNA genes and 3210 ORFs. The percentages of ORFs assigned to CAZy, COG, and KEGG databases were 5.5, 86.2 and 45.5%, respectively. Comparative genomic analysis indicated that the pan- and core-genomes of the genus Aestuariibaculum consisted of 4826 and 2257 orthologous genes, respectively. Carbohydrate-active enzyme annotations of the genus Aestuariibaculum genomes revealed that they shared three polysaccharide lyase (PL) families including PL1, PL22 and PL42. Meanwhile, one carotenoid biosynthetic gene cluster related to biosynthesizing flexixanthin was found in the genus Aestuariibaculum. Furthermore, the core-genome of the genus Aestuariibaculum showed that this genus played a role in cleaving pectate, degrading ulvan, and biosynthesizing carotenoids. This study is a complete genomic report of the genus Aestuariibaculum and broadens understandings of its ecological roles and biotechnological applications., Competing Interests: Declaration of Competing Interest The authors declare that there are no conflicts of interest., (Copyright © 2023 Elsevier B.V. All rights reserved.)

The production and use of plastic blends have been gradually increasing owing to their versatility and low cost. However, the photodegradation of plastic blends in seawater and the potential risk to the marine environment are still not well understood. In this study, plastic blends including polypropylene/thermoplastic starch blends(PP/TPS) and polylactic acid/poly(butylene adipate-co-terephthalate)/thermoplastic starch blends(PLA/PBAT/TPS) were investigated. The corresponding neat polymers, namely polypropylene(PP) and polylactic acid(PLA), were set as control groups. We investigated the formation of MPs and the changes in the physicochemical properties of plastic blends after photodegradation in seawater. The size distribution of MPs indicated that PP/TPS and PLA/PBAT/TPS were more likely to produce small-sized particles after photodegradation than PP and PLA owing to their poorer mechanical properties and lower resistance to UV irradiation. Noticeable surface morphology alterations, including cracks and wrinkles, were observed for plastic blends following photodegradation, whereas PP and PLA were relatively resistant. After photodegradation, the ATR-FTIR spectrum of PP/TPS and PLA/PBAT/TPS showed a significant decrease in the characteristic bands of thermoplastic starch(TPS), indicating the degradation of their starch fractions. The C 1 s spectra demonstrated that aged plastic blends contained fewer -OH groups than the pristine MPs did, further confirming the photodegradation of TPS. These results indicate that PP/TPS and PLA/PBAT/TPS had a higher degree of photodegradation than PP and PLA and thereby generated more small-sized MPs. In summary, plastic blends may pose a higher risk to the marine environment than neat polymers, and caution should be taken in the production and use of plastic blends.

A Gram-stain-negative, strictly aerobic and rod- to coccoid-shaped bacterium, designated as strain M366 T , was isolated from coastal sediment of Jiaoshanjiao, Zhejiang Province, PR China (121°54' E 29 °38' N). The draft genome of strain M366 T was 3 225 479 bp long (with 55.6 mol% G+C content) and assembled into four contigs. The N50 value was 563 270 bp and the genomic completeness and contamination were estimated to be 99.34 and 0.05 %, respectively. Colonies of strain M366 T were yellow-orange, 1 mm in diameter, round, opaque, smooth and convex after incubation on marine agar at 30 °C for 3 days. Cells were catalase-positive but oxidase-negative. Strain M366 T was observed to grow at 20-40 °C (optimum, 30 °C), pH 5.5-9.0 (optimum, pH 6.5-7.0) and with 0.5-8.0 % (w/v) NaCl (optimum, 2.5 %). Strain M366 T shown highest 16S rRNA gene sequence similarity of 98.1 % to Robiginitalea sediminis O458 T , 95.6-95.9 % to other type strains of the genus Robiginitalea and below 93 % to other genera. The average nucleotide identity and digital DNA-DNA hybridization values between strain M366 T and its closely related Robiginitalea species were 71.1-75.9 % and 17.5-19.0 %. Menaquinone-6 was the only respiratory quinone. The major fatty acids (>10 %) were iso-C 15 : 0 , iso-C 17 : 0 3-OH and summed feature 1 (iso-C 15 : 1  h and/or C 13 : 0 3-OH). The main polar lipids included phosphatidylethanolamine, two unidentified phospholipid, two unidentified aminophospholipid, one unidentified glycolipid and five unidentified lipids. According to the above results, Robiginitalea aestuariiviva sp. nov. is proposed and the type strain is M366 T (=KCTC 92866 T =MCCC 1K04524 T =CGMCC 1.61708 T ).

Background: The pathological mechanism of intervertebral disc degeneration (IDD) is an unanswered question that we are committed to exploring. A20 is an anti-inflammatory protein of nucleus pulposus (NP) cells and plays a protective role in intervertebral disc degeneration., Objective: This study aims to investigate the molecular mechanism by which A20 attenuates disc degeneration., Methods: The proteins of interest were measured by immunoblotting, immunofluorescence, ELISA assay, and immunohistochemical technique to conduct related experiments. Immunofluorescence assays and mitochondrial membrane potential (JC-1) were used to assess mitophagy and mitochondrial fitness, respectively., Results: Here, we demonstrated that A20 promoted mitophagy, attenuated pyroptosis, and inhibited the degradation of the extracellular matrix, consequently significantly ameliorating disc degeneration. Mechanistically, A20 reduces pyroptosis and further suppresses cellular mTOR activity. On the one hand, A20-induced mTOR inhibition triggers BNIP3-mediated mitophagy to ensure mitochondrial fitness under LPS stimulation, as a result of mitigating mitochondrial dysfunction induced by LPS. On the other hand, A20-induced mTOR inhibition reduces the loss of mitochondrial membrane potential and the generation of Mitochondrial ROS., Conclusion: The study revealed that A20 promotes BNIP3-mediated mitophagy by suppressing mTOR pathway activation against LPS-induced pyroptosis., (© 2022. The Author(s) under exclusive licence to The Genetics Society of Korea.)

A Gram-stain negative, strictly aerobic, and rod-shaped bacterium, designated as strain L182 T , was isolated from coastal sediment in Beihai, Guangxi Province, PR China. Colonies of strain L182 T were yellow, 2 mm in diameter, round, opaque, smooth and convex after incubation on marine ager at 30 °C for 3 days. Cells were catalase-positive but oxidase-negative. Growth of strain L182 T was observed at 4-40 °C (optimum, 25 °C), pH 5.5-10.0 (optimum, pH 5.5-8.0) and with 0-6% (w/v) NaCl (optimum, 0.5-4.0%). The G + C content based on the genome sequence was 36.0%. The only respiratory quinone was MK-6. The main polar lipids included phosphatidylethanolamine, phosphatidylglycerol, one unidentified aminophospholipid, one unidentified glycolipids, four unidentified aminolipids and six unidentified lipids. The major fatty acids (> 10%) were iso-C 15:0 , iso-C 15:1 G and iso-C 17:0 3-OH. The 16S rRNA gene sequence similarity between strain L182 T and Aestuariibaculum suncheonense SC17 T was 98.2%, and the similarities with other type strains of the genus Aestuariibaculum were 96.1-97.2%. The average nucleotide identity and in silicon DNA-DNA hybridization values between the strain L182 T and its closely related Aestuariibaculum species were 80.8-85.2% and 22.0-29.5%. According to the above results, Aestuariibaculum lutulentum sp. nov. was proposed as a novel species. The type strain is L182 T (= MCCC 1K08065 T  = KCTC 92530 T )., (© 2023. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Bone marrow mesenchymal stem cells (BMSCs) have been investigated as cellular therapeutics for intervertebral disc degeneration. However, transplanted BMSCs are prone to be damaged. TNF-α is reported to extensively promote degeneration process. Nevertheless, the relationship between BMSCs senescence and TNF-α-induced stress has not been elucidated. Previous studies showed that mitophagy is a crucial factor in maintaining cellular homeostasis. Hence, we sought to clarify the role and mechanism of mitophagy in TNF-α-induced biological changes of BMSCs. Here, we found that TNF-α caused transient senescent damage in the early stage. Meanwhile, Parkin-mediated mitophagy was initiated and weakened the damage through maintaining mitochondria homeostasis. After inhibiting mitophagy by knockdown of Parkin, TNF-α irreversibly caused cellular senescence. These results suggested that Parkin-mediated mitophagy played protective role in BMSCs in response to TNF-α, which could be a crucial therapeutic target in the future., (Copyright © 2022. Published by Elsevier Inc.)

Purpose: Cell senescence plays a vital role in intervertebral disc degeneration. The regulatory mechanism of the cellular senescence of nucleus pulposus cells has not been fully elucidated. A recent study identified GATA4 as an emerging regulator of IMR90 cellular senescence. However, whether GATA4 controls senescence in nucleus pulposus cells still needs to be explored., Methods: Nucleus pulposus cells were exposed to acidified medium mimic the acid environment of intervertebral disc degeneration., Results: We found that GATA4 protein expression was significantly upregulated in older rats and nucleus pulposus cells undergoing stress-induced aging. Moreover, the data indicated that inhibition of GATA4 significantly inhibited the senescence of nucleus pulposus cells cultured under acidic conditions and that over expression of GATA4 promoted a senescence phenotype. The NF-κB pathway has been confirmed in this study to play a role in the regulation of nucleus pulposus cell senescence by GATA4. By using the NF-κB pathway inhibitor, PDTC (100 μmol/L), significantly decreased the IL-6, matrix metallopeptidase (MMP)-2, MMP-3, MMP-9, MMP-13, ADAM metallopeptidase with thrombospondin type 1 motif (ADAMTS)-4, ADAMTS-5 expression level, and increased Aggrecan and typeⅡcollagen expression level in GATA4 transfected nucleus pulposus cells compared with the group in the absence of PDTC., Conclusion: This outcome suggested that GATA4 might play a significant role in nucleus pulposus cell senescence through the NF-κB signaling pathway, and GATA4 is a promising target for intervertebral disc degeneration treatment in the future., (Copyright © 2022. Published by Elsevier B.V.)

Background: A20 is an anti-inflammatory molecule in nucleus pulposus (NP) cells. The anti-inflammatory properties of A20 are mainly attributed to its ability to suppress the NF-κB pathway. However, A20 can protect cells from death independently of NF-κB regulation. This study aimed to investigate the effects of A20 on pyroptosis and apoptosis of NP cells induced by lipopolysaccharide (LPS)., Methods: NP cells induced by LPS were used as an in vitro model of the inflammatory environment of the intervertebral disc. Pyroptosis, apoptosis, and mitophagy marker proteins were detected. Then, NP cells were transfected with A20 overexpressed lentivirus or A20-siRNA. Annexin V FITC/PI, Western blotting, and immunofluorescence assays were used to detect the apoptosis, pyroptosis, and mitophagy of NP cells. Furthermore, the expressions of A20, related proteins, and related inflammatory cytokines were detected by western blotting, and ELISA., Results: Apoptosis and pyroptosis of NP cells increased gradually treated with LPS for 12 h, 24 h, and 48 h. Differently, the level of mitophagy increased first and then decreased, and was the highest at LPS treatment for 12 h. Overexpression or knockdown of A20 in NP cells revealed that A20 attenuated the pyroptosis, apoptosis, and production of inflammatory cytokines of NP cells induced by LPS, while A20 sponsored mitophagy, reduced ROS production and collapse of mitochondrial membrane potential (ΔΨm). Moreover, A20 also promoted mitochondrial dynamic homeostasis and attenuated LPS-induced excessive mitochondrial fission. Excitingly, inhibition of mitophagy attenuated the effect of A20 on the negative regulation of pyroptosis of NP cells induced by LPS. Pyroptosis was accompanied by a large release of inflammatory cytokines. Inhibition of pyroptosis also significantly reduced apoptosis of NP cells. Finally, The mitochondria-targeted active peptide SS-31 inhibited LPS-induced pyroptosis and ROS production in NP cells., Conclusions: To sum up, A20 attenuates pyroptosis and apoptosis of NP cells via promoting mitophagy and stabilizing mitochondrial dynamics. Besides, A20 reduces LPS-induced NP cell apoptosis by inhibiting NLRP3 inflammasome-mediated pyroptosis. It provides theoretical support for the reduction of functional NP cell loss in the intervertebral disc through the gene-targeted intervention of A20., (© 2022. The Author(s), under exclusive licence to Springer Nature Switzerland AG.)

Minimally invasive repair strategies are a very promising approach for the treatment of intervertebral disc degeneration (IDD). In recent years, small extracellular vesicles (sEVs) secreted from mesenchymal stem cells (MSCs) have been shown great potential in alleviating IDD. However, in vitro experiments, MSCs are usually exposed to a normoxic micro-environment, which differs greatly from the hypoxic micro-environment in vivo. The primary purpose of our research was to determine whether sEVs isolated from MSCs under hypoxic status (H-sEVs) exhibit a more beneficial effect on protecting IDD compared with sEVs derived from MSCs under normoxic status (N-sEVs). A tail IDD rat model and a series of experiments in vitro were conducted to compare the beneficial effects of PBS, N-sEVs, and H-sEVs treatment. Then, to validate the role of sEVs miRNAs in IDD, a miRNA microarray sequencing analysis and a series of rescue experiments were conducted. Luciferase activity, RNA-ChIP and western blot were performed to explore the potential mechanisms. The results indicate that sEVs alleviate IDD by ameliorating the homeostatic imbalance between anabolism and catabolism in vivo and in vitro. Microarray sequencing result shows that miR-17-5p is maximally enriched in H-sEVs. Toll-like receptor 4 (TLR4) was determined to be a target downstream gene of miR-17-5p. Finally, it was found that H-sEVs miR-17-5p may modulate proliferation and synthesis of human nucleus pulposus cells (HNPCs) matrix via TLR4 pathway. In conclusion, H-sEVs miR-17-5p alleviate IDD via promoting HNPCs matrix proliferation and synthesis, providing new therapeutic targets for IDD. STATEMENT OF SIGNIFICANCE: Intervertebral disc degeneration (IDD) is the primary cause of low back pain (LBP), which is a huge burden to society. Our research demonstrates for the first time that hypoxic pretreatment of small extracellular vesicles (H-sEVs) effectively alleviated the progress of IDD. In short, in the present research, we found that H-sEVs miR-17-5p could modulate proliferation and synthesis of nucleus pulposus cells (NPCs) matrix via TLR4/PI3K/AKT pathway. Therefore, hypoxic pre-treatment is a prospective and efficient method to optimize the therapeutic effect of MSCs-derived sEVs. miRNA and MSCs-derived sEVs combination may be a promising therapeutic approach for IDD., 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 © 2021 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.)

Evidence has shown that effects from inflammation and mitochondrial dysfunction lead to pyroptosis and apoptosis of nucleus pulposus (NP) cells. Damaged mitochondria release dangerous molecules such as reactive oxygen species (ROS), activating the NLRP3 inflammasome. SS-31 is a mitochondria-targeting peptide that has been used in the treatment of many diseases by scavenging ROS and ameliorating mitochondrial function. This study found that SS-31 ameliorated lipopolysaccharide (LPS)-induced loss of cell viability, ROS production, and apoptosis in NP cells. Moreover, mitochondrial dynamics and ATP synthesis were restored on pretreatment with SS-31 compared with the LPS group. For the molecular mechanism research, SS-31 stabilized mitochondrial morphology and inhibited the activation of the NF-κB pathway and the activation of the NLRP3 inflammasome. To evaluate whether the inhibition of NLRP3 inflammasome activation by SS-31 is dependent on the clearance of mitochondrial ROS, we comparatively analyzed the activation of NLRP3 inflammasome in NP cells pretreated with SS-31 and the ROS scavenger N-acetyl-L-cysteine (NAC). The results indicate that SS-31 could inhibit NLRP3 inflammasome activation by limiting the production of mitochondrial ROS. To sum up, our results revealed that SS-31 inhibits LPS-induced apoptosis, pyroptosis, and inflammation in NP cells via scavenging ROS and maintaining the stability of mitochondrial dynamics, which could be considered a promising therapeutic intervention for disk degeneration.