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Endometrium fibrosis is the leading cause of uterine infertility. Macrophages participated in the occurrence and development of endometrial fibrosis. We previously reported that human umbilical cord multipotent stromal cells (hUC-MSCs) exerted their therapeutic effect in a macrophage-dependent manner in endometrial fibrosis. However precise mechanisms by which hUC-MSCs may influence macrophages in endometrial fibrosis remain largely unexplored. Here, we demonstrated that abnormal iron and lipid metabolism occurred in patients with intrauterine adhesions (IUA) and murine models. Ferroptosis has been proven to contribute to the progression of fibrotic diseases. Our results revealed that pharmacological activation of ferroptosis by Erastin aggravated endometrial fibrosis, while inhibition of ferroptosis by Ferrostatin-1 ameliorated endometrial fibrosis in vivo. Moreover, ferroptosis of macrophages was significantly upregulated in endometria of IUA murine models. Of note, transcriptome profiles revealed that CD36 gene expression was significantly increased in patients with IUA and immunofluorescence analysis showed CD36 protein was mainly located in macrophages. Silencing CD36 in macrophages could reverse cell ferroptosis. Dual luciferase reporter assay revealed that CD36 was the direct target of activation transcription factor 3 (ATF3). Furthermore, through establishing coculture system and IUA murine models, we found that hUC-MSCs had a protective role against macrophage ferroptosis and alleviated endometrial fibrosis related to decreased CD36 and ATF3. The effect of hUC-MSCs on macrophage ferroptosis was attributed to the upregulation of amphiregulin (AREG). Our data highlighted that macrophage ferroptosis occurred in endometrial fibrosis via the ATF3-CD36 pathway and hUC-MSCs protected against macrophage ferroptosis to alleviate endometrial fibrosis via secreting AREG. These findings provided a potential target for therapeutic implications of endometrial fibrosis., (© The Author(s) 2024. Published by Oxford University Press. 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: Intrauterine adhesion (IUA) is a condition caused due to damage or infection of the endometrium. It is characterized by continuous inflammation and following fibrosis and dysfunction. However, the current animal IUA models have several disadvantages, including complex operation, high mortality, and many extra distractions owing to opening of the abdominal cavity to expose the uterus. Mesenchymal stem cells (MSCs), which have been used in treatment of IUA, are heterogeneous and immunosuppressive. However, their therapeutic effect is not as good as expected., Methods: Here, we successfully built a new murine IUA model, called electric tool-scratching IUA model, and applied it in our experiments to investigate the efficacy of tumor necrosis factor-α (TNF-α) primed MSCs (T-MSCs). In the new model, we used a self-made electric tool that can cause mechanical damage to the endometrium without opening the abdominal cavity. ELISA and histological staining analysis were performed to evaluate pathological features of IUA. qRT-PCR, flow cytometry and immunofluoresence staining were performed to detect the phenotypes of macrophages. TMT proteomics quantification and western blotting assay were performed to analyze the differentially expressed proteins of MSC exosomes., Results: Based on the new IUA model, we found TNF-α pretreatment could enhance the ability of MSCs to relieve inflammation and reduce endometrium fibrosis. Mechanistically, T-MSC promoted macrophage polarization to M2 phenotype through exosomes. Subsequently, we found the expression of Galectin-1 was increased in T-MSC exosomes. Finally, we analyzed the gene expression pattern of Galectin-1 treated macrophages and found Galectin-1 promoted macrophage polarization to M2 phenotype mainly through the Jak-STAT signaling pathway., Conclusions: Our studies proposed an innovative mouse model and a better MSC treatment strategy for IUA., 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 © 2022 Li, Pan, Yang, Wang, Jiang, Dou and Hou.)

Intrauterine adhesions (IUA) are characterized by endometrial fibrosis and impose a great challenge for female reproduction. IL-34 is profoundly involved in various fibrotic diseases through regulating the survival, proliferation, and differentiation of monocytes/macrophages. However, it remains unclear how IL-34 regulates monocytes/macrophages in context of IUA. Here, we showed that the expression level of IL-34 and the amount of CX3CR1+ monocytes/macrophages were significantly increased in endometrial tissues of IUA patients. IL-34 promoted the differentiation of monocytes/macrophages, which express CX3CR1 via CSF-1R/P13K/Akt pathway in vitro. Moreover, IL-34-induced CX3CR1+ monocytes/macrophages promoted the differentiation of endometrial stromal cells into myofibroblasts. Of note, IL-34 caused endometrial fibrosis and increased the amount of CX3CR1+ monocytes/macrophages in endometrial tissues in vivo. IL-34 modulated endometrial fibrosis by regulating monocytes/macrophages since the elimination of endometrial monocytes/macrophages significantly suppressed the profibrotic function of IL-34. Finally, blocking of IL-34 in the LPS-IUA model resulted in the improvement of endometrial fibrosis and decreased number of CX3CR1+ monocytes/macrophages. Our studies uncover the novel mechanism of interaction between IL-34-induced CX3CR1+ monocytes/macrophages and endometrial stromal cells in endometrial fibrosis pathogenesis, and highlight IL-34 as a critical target for treating IUA., (© 2021 Wiley-VCH GmbH.)

Background: Sepsis is a life-threatening condition caused by dysregulated host responses to infection. Macrophages, which recognize microbial infections through identification of bacterial markers such as lipopolysaccharide (LPS), are crucial to the pathogenesis of sepsis-associated liver injury. However, the understanding of the SPIONs-mediated modulation of macrophage responses in LPS-induced sepsis and liver injury is limited., Materials and Methods: Superparamagnetic iron oxide nanoparticles (SPIONs) of γ-Fe 2 O 3 nanoparticles were prepared, and their morphology and magnetic properties were characterized., Results: Using a murine model of LPS-induced sepsis and liver injury, we found that SPIONs alleviated LPS-induced sepsis, preventing infiltration of inflammatory cells into the liver. SPIONs also increased the level of interleukin-10 (IL-10) in liver macrophages, while SPIONs's effect on LPS-induced sepsis was abrogated in IL-10 -/- mice, indicating that the protective effect of SPIONs is dependent on IL-10 + macrophages. Moreover, SPIONs activated macrophage autophagy to increase IL-10 production, which was markedly attenuated by autophagy inhibition. Furthermore, SPIONs upregulated the expression of Caveolin-1 (Cav1) in macrophages, which plays a role in cellular uptake of metallic nanoparticles. Interestingly, activation of Cav1 and Notch1/HES1 signaling was involved in SPIONs-induced autophagy in both RAW 264.7 cells and bone marrow-derived macrophages (BMDMs). Our data reveal a novel mechanism for SPIONs -induced autophagy in macrophages, which occurs through activation of the Cav1-Notch1/HES1 signaling pathway, which promotes the production of IL-10 in macrophages, leading to inhibition of inflammation in LPS-induced sepsis and liver injury., Conclusion: Our results suggest that SPIONs may represent a potential therapeutic agent for the treatment of sepsis and sepsis-induced liver injury., Competing Interests: The authors report no conflicts of interest in this work., (© 2019 Xu et al.)

Macrophages orchestrate inflammation and control the promotion or inhibition of tumors and metastasis. Ferumoxytol (FMT), a clinically approved iron oxide nanoparticle, possesses anti-tumor therapeutic potential by inducing pro-inflammatory macrophage polarization. Toll-like receptor 3 (TLR3) activation also potently enhances the anti-tumor response of immune cells. Herein, the anti-tumor potential of macrophages harnessed by FMT combined with the TLR3 agonist, poly (I:C) (PIC), and FP-NPs (nanoparticles composed of amino-modified FMT (FMT-NH 2 ) surface functionalized with PIC) was explored. Methods: Proliferation of B16F10 cells co-cultured with macrophages was measured using immunofluorescence or flow cytometry (FCM). Phagocytosis was analyzed using FCM and fluorescence imaging. FP-NPs were prepared through electrostatic interactions and their properties were characterized using dynamic light scattering, transmission electron microscopy, and gel retardation assay. Anti-tumor and anti-metastasis effects were evaluated in B16F10 tumor-bearing mice, and tumor-infiltrating immunocytes were detected by immunofluorescence staining and FCM. Results: FMT, PIC, or the combination of both hardly impaired B16F10 cell viability. However, FMT combined with PIC synergistically inhibited their proliferation by shifting macrophages to a tumoricidal phenotype with upregulated TNF-α and iNOS, increased NO secretion and augmented phagocytosis induced by NOX2-derived ROS in vitro . Combined treatment with FMT/PIC and FMT-NH 2 /PIC respectively resulted in primary melanoma regression and alleviated pulmonary metastasis with elevated pro-inflammatory macrophage infiltration and upregulation of pro-inflammatory genes in vivo . In comparison, FP-NPs with properties of internalization by macrophages and accumulation in the lung produced a more pronounced anti-metastatic effect accompanied with decreased myeloid-derived suppressor cells, and tumor-associated macrophages shifted to M1 phenotype. In vitro mechanistic studies revealed that FP-NPs nanoparticles barely affected B16F10 cell viability, but specifically retarded their growth by steering macrophages to M1 phenotype through NF-κB signaling. Conclusion: FMT synergized with the TLR3 agonist PIC either in combination or as a nano-composition to induce macrophage activation for primary and metastatic melanoma regression, and the nano-composition of FP-NPs exhibited a more superior anti-metastatic efficacy., Competing Interests: Competing Interests: The authors have declared that no competing interest exists.

Intrauterine adhesion (IUA) is characterized by the presence of fibrosis in the uterine cavity. It is mainly caused by infection or trauma to the endometrium, and it imposes a great challenge to female reproductive health. Mesenchymal stem cells (MSCs) have been used to regenerate the human endometrium in patients with IUA, but stem cell therapy is not curative in some patients. Melatonin (MT) was reported as a potential modulator of MSCs. However, it remains unclear whether MSCs pretreated with MT exert an improved therapeutic effect on IUA. In this study, an IUA model was established using our invented electric scratching tool. Our results illustrated that MT-pretreated MSCs significantly attenuated the development of IUA. Moreover, MT-pretreated MSCs highly expressed galectin-3 (Gal-3), which enhanced MSC proliferation and migration and influenced macrophage polarization. Of note, IUA mice exhibited colonic injury, and MT-pretreated MSCs alleviated this injury by normalizing colonic microbial communities and recruiting macrophages. Furthermore, inhibition of sympathetic nerves had no effect on IUA progression but delayed colonic injury, and Gal-3 combined with norepinephrine better promoted M2-like macrophage polarization and inhibited M1-like macrophage polarization. Together, these data indicated that MT-primed MSCs can ameliorate injury of both the uterus and colon in an IUA model through high Gal-3 expression to influence sympathetic nerves and in turn affect the polarization and recruitment of macrophages. [ABSTRACT FROM AUTHOR]

Intrauterine adhesions (IUA) are characterized by endometrial fibrosis and impose a great challenge for female reproduction. IL‐34 is profoundly involved in various fibrotic diseases through regulating the survival, proliferation, and differentiation of monocytes/macrophages. However, it remains unclear how IL‐34 regulates monocytes/macrophages in context of IUA. Here, we showed that the expression level of IL‐34 and the amount of CX3CR1+ monocytes/macrophages were significantly increased in endometrial tissues of IUA patients. IL‐34 promoted the differentiation of monocytes/macrophages, which express CX3CR1 via CSF‐1R/P13K/Akt pathway in vitro. Moreover, IL‐34‐induced CX3CR1+ monocytes/macrophages promoted the differentiation of endometrial stromal cells into myofibroblasts. Of note, IL‐34 caused endometrial fibrosis and increased the amount of CX3CR1+ monocytes/macrophages in endometrial tissues in vivo. IL‐34 modulated endometrial fibrosis by regulating monocytes/macrophages since the elimination of endometrial monocytes/macrophages significantly suppressed the profibrotic function of IL‐34. Finally, blocking of IL‐34 in the LPS‐IUA model resulted in the improvement of endometrial fibrosis and decreased number of CX3CR1+ monocytes/macrophages. Our studies uncover the novel mechanism of interaction between IL‐34‐induced CX3CR1+ monocytes/macrophages and endometrial stromal cells in endometrial fibrosis pathogenesis, and highlight IL‐34 as a critical target for treating IUA. [ABSTRACT FROM AUTHOR]

• TLR7 increases uPAR expression on macrophages. • TLR7 regulates uPAR via ERK/JNK signal pathways. • Increased uPAR induced by TLR7 impairs macrophage efferocytosis. The accumulation of apoptotic cells is one of the pathological characteristics of systemic lupus erythematosus (SLE). The expression of urokinase-type plasminogen activator receptor (uPAR) has been reported to be increased in SLE patients and to be involved in macrophage efferocytosis. Although the toll-like receptor 7 (TLR7) is also over-expressed in lupus, its relationship to uPAR and its role in macrophage efferocytosis in lupus is still unclear. In the present study, we revealed that apoptotic cells accumulate in the spleen, macrophage efferocytosis is impaired, and uPAR is increased in the spleen and peritoneal macrophages of the TLR7 agonist imiquimod (IMQ)-induced SLE mouse model. Moreover, TLR7 upregulated uPAR expression in the mouse macrophage RAW 264.7 cells in vitro. The same results were also obtained using peritoneal macrophages of female Balb/c mice. When uPAR levels in peritoneal macrophages were knocked down by siRNA or inhibited by the peptide inhibitor UPARANT, and cells further treated with the TLR7 agonist R848, efferocytosis of peritoneal macrophages on apoptotic cells was restored. These results indicated that TLR7 activation impaired efferocytosis via uPAR in mouse peritoneal macrophages. Furthermore, TLR7 regulated uPAR expression via ERK/JNK signaling in macrophages. These results suggest that uPAR may be an important factor related to the accumulation of apoptotic cells in SLE. [ABSTRACT FROM AUTHOR]