Deletion of p38 MAPK in macrophages ameliorates peritoneal fibrosis and inflammation in peritoneal dialysis.

One of the most common causes of peritoneal dialysis withdrawal is ultrafiltration failure which is characterized by peritoneal membrane thickening and fibrosis. Although previous studies have demonstrated the inhibitory effect of p38 MAPK inhibitors on peritoneal fibrosis in mice, it was unclear which specific cells contribute to peritoneal fibrosis. To investigate the role of p38 MAPK in peritoneal fibrosis more precisely, we examined the expression of p38 MAPK in human peritoneum and generated systemic inducible p38 MAPK knockout mice and macrophage-specific p38 MAPK knockout mice. Furthermore, the response to lipopolysaccharide (LPS) was assessed in p38 MAPK-knocked down RAW 264.7 cells to further explore the role of p38 MAPK in macrophages. We found that phosphorylated p38 MAPK levels were increased in the thickened peritoneum of both human and mice. Both chlorhexidine gluconate (CG)-treated systemic inducible and macrophage-specific p38 MAPK knockout mice ameliorated peritoneal thickening, mRNA expression related to inflammation and fibrosis, and the number of αSMA- and MAC-2-positive cells in the peritoneum compared to CG control mice. Reduction of p38 MAPK in RAW 264.7 cells suppressed inflammatory mRNA expression induced by LPS. These findings suggest that p38 MAPK in macrophages plays a critical role in peritoneal inflammation and thickening.

MiR-454-3p regulates high glucose-induced mesothelial-mesenchymal transition and glycolysis in peritoneal mesothelial cells by targeting STAT3.

BACKGROUND: The quality of life of patients receiving long-term peritoneal dialysis (PD) is significantly impacted by the onset of peritoneal fibrosis (PF), and one of the pathological changes is mesothelial-mesenchymal transition (MMT). In this study, we investigated the potential roles of miR-454-3p and signal transducer and activator of transcription 3 (STAT3) in the progression of peritoneal MMT and the underlying mechanisms. METHODS: Peritoneums were collected to detect morphology via hematoxylin-eosin staining and differentially expressed miRNAs were detected via RT-qPCR. PD effluent-derived cell populations in the peritoneal cavity were isolated from the effluents of 20 PD patients to determine miR-454-3p, STAT3, and MMT markers via Western blotting and RT-qPCR. The relationship between miR-454-3p and STAT3 was examined via a dual-luciferase reporter assay. Western blotting and RT-qPCR were utilized to evaluate the expression of STAT3, MMT markers, and glycolytic enzymes. Immunofluorescence staining revealed the localization and expression of MMT markers and STAT3. RESULTS: MiR-454-3p was downregulated in the peritoneums and PD effluent-derived cell populations of long-term PD patients. High glucose (HG) treatment promoted HMrSV5 cell MMT and glycolysis. MiR-454-3p overexpression alleviated HG-induced MMT and suppressed the expression of STAT3 and glycolytic enzymes. In contrast, the miR-454-3p inhibitor exacerbated HG-induced MMT and promoted the expression of glycolytic enzymes and STAT3. Moreover, STAT3 was the target of miR-454-3p. CONCLUSIONS: This study demonstrated the protective role of miR-454-3p in HG-induced MMT and glycolysis in HMrSv5 cells, suggesting that miR-454-3p may prevent MMT by suppressing glycolytic enzymes via the STAT3/PFKFB3 pathway in the HG environment.

LncRNA RPL29P2 promotes peritoneal fibrosis and impairs peritoneal transport function via miR-1184 in peritoneal dialysis.

Peritoneal dialysis (PD), hemodialysis and kidney transplantation are the three therapies to treat uremia. However, PD is discontinued for peritoneal membrane fibrosis (PMF) and loss of peritoneal transport function (PTF) due to damage from high concentrations of glucose in PD fluids (PDFs). The mechanism behind PMF is unclear, and there are no available biomarkers for the evaluation of PMF and PTF. Using microarray screening, we found that a new long noncoding RNA (lncRNA), RPL29P2, was upregulated in the PM (peritoneal membrane) of long-term PD patients, and its expression level was correlated with PMF severity and the PTF loss. In vitro and rat model assays suggested that lncRNA RPL29P2 targets miR-1184 and induces the expression of collagen type I alpha 1 chain (COL1A1). Silencing RPL29P2 in the PD rat model might suppress the HG-induced phenotypic transition of Human peritoneal mesothelial cells (HPMCs), alleviate HG-induced fibrosis and prevent the loss of PTF. Overall, our findings revealed that lncRNA RPL29P2, which targets miR-1184 and collagen, may represent a useful marker and therapeutic target of PMF in PD patients.

BMSC-derived Exosomes Ameliorate Peritoneal Dialysis-associated Peritoneal Fibrosis via the Mir-27a-3p/TP53 Pathway.

OBJECTIVE: Peritoneal fibrosis (PF) is the main cause of declining efficiency and ultrafiltration failure of the peritoneum, which restricts the long-term application of peritoneal dialysis (PD). This study aimed to investigate the therapeutic effects and mechanisms of bone marrow mesenchymal stem cells-derived exosomes (BMSC-Exos) on PF in response to PD. METHODS: Small RNA sequencing analysis of BMSC-Exos was performed by second-generation sequencing. C57BL/6J mice were infused with 4.25% glucose-based peritoneal dialysis fluid (PDF) for 6 consecutive weeks to establish a PF model. A total of 36 mice were randomly divided into 6 groups: control group, 1.5% PDF group, 2.5% PDF group, 4.25% PDF group, BMSC-Exos treatment group, and BMSC-Exos+TP53 treatment group. Reverse transcription quantitative polymerase chain reaction (RT-qPCR) was performed to measure the expression level of miR-27a-3p in BMSC-Exos and peritoneum of mice treated with different concentrations of PDF. HE and Masson staining were performed to evaluate the extent of PF. The therapeutic potential of BMSC-Exos for PF was examined through pathological examination, RT-qPCR, Western blotting, and peritoneal function analyses. Epithelial-mesenchymal transition (EMT) of HMrSV5 was induced with 4.25% PDF. Cells were divided into control group, 4.25% PDF group, BMSC-Exos treatment group, and BMSC-Exos+TP53 treatment group. Cell Counting Kit-8 assay was used to measure cell viability, and transwell migration assay was used to verify the capacity of BMSC-Exos to inhibit EMT in HMrSV5 cells. RESULTS: Small RNA sequencing analysis showed that miR-27a-3p was highly expressed in BMSC-derived exosomes compared to BMSCs. The RT-qPCR results showed that the expression of miR-27a-3p was upregulated in BMSC-Exos, but decreased in PD mice. We found that PF was glucose concentration-dependently enhanced in the peritoneum of the PD mice. Compared with the control mice, the PD mice showed high solute transport and decreased ultrafiltration volume as well as an obvious fibroproliferative response, with markedly increased peritoneal thickness and higher expression of α-SMA, collagen-I, fibronectin, and ECM1. The mice with PD showed decreased miR-27a-3p. Peritoneal structural and functional damage was significantly attenuated after BMSC-Exos treatment, while PF and mesothelial damage were significantly ameliorated. Additionally, markers of fibrosis (α-SMA, collagen-I, fibronectin, ECM1) and profibrotic cytokines (TGF-ß1, PDGF) were downregulated at the mRNA and protein levels after BMSC-Exos treatment. In HMrSV5 cells, BMSC-Exos reversed the decrease in cell viability and the increase in cell migratory capacity caused by high-glucose PDF. Western blotting and RT-qPCR analysis revealed that BMSC-Exos treatment resulted in increased expression of E-cadherin (epithelial marker) and decreased expression of α-SMA, Snail, and vimentin (mesenchymal markers) compared to those of the 4.25% PDF-treated cells. Importantly, a dual-luciferase reporter assay showed that TP53 was a target gene of miR-27a-3p. TP53 overexpression significantly reversed the decreases in PF and EMT progression induced by BMSC-Exos. CONCLUSION: The present results demonstrate that BMSC-Exos showed an obvious protective effect on PD-related PF and suggest that BMSC-derived exosomal miR-27a-3p may exert its inhibitory effect on PF and EMT progression by targeting TP53.

MiR-132-3p suppresses peritoneal fibrosis induced by peritoneal dialysis via targeting TGF-ß1/Smad2/3 signaling pathway.

BACKGROUND: Peritoneal fibrosis (PF) is the main complication of peritoneal dialysis (PD) and the most common cause of cessation from PD. There is still no effective therapeutic approach to reserve PF. We aimed to investigate the role of miR-132-3p and underlying potential mechanisms in PF. METHODS: A total of 18 Sprague-Dawley (SD) rats were divided randomly into three groups (n = 6): (i)Control group (ii)PF group (iii)PF+Losartan group; Rats in the PF group and PF+Losartan group received daily intraperitoneal injections of 3 mg/kg chlorhexidine for 14 days, and rats in the PF+Losartan group simultaneously received daily intraperitoneal injections of 2 mg/kg losartan for 14 days. The control group was injected with saline in the same volume. Met-5A cells were treated for 24h with TGF-ß1 dissolved in recombinant buffered saline at a concentration of 10 ng/ml, meanwhile, PBS solution as a negative control. The human peritoneal solution was collected for the detection of miR-132-3p. RESULTS: In vivo, SD rats were infused with chlorhexidine to establish PF model, and we found that miR-132-3p significantly decreased and the expressions of transforming growth factor-ß1 (TGF-ß1), and Smad2/3 were up-regulated in PF. In vitro, miR-132-3p mimics suppressed TGF-ß1/Smad2/3 activity, whereas miR-132-3p inhibition activated the pathway. In human peritoneal solution, we found that the expression of miR-132-3p decreased in a time-dependent model and its effect became more pronounced with longer PD duration. CONCLUSION: MiR-132-3p ameliorated PF by suppressing TGF-ß1/Smad2/3 activity, suggesting that miR-132-3p represented a potential therapeutic approach for PF.

BRG1 accelerates mesothelial cell senescence and peritoneal fibrosis by inhibiting mitophagy through repression of OXR1.

Peritoneal mesothelial cell senescence promotes the development of peritoneal dialysis (PD)-related peritoneal fibrosis. We previously revealed that Brahma-related gene 1 (BRG1) is increased in peritoneal fibrosis yet its role in modulating peritoneal mesothelial cell senescence is still unknown. This study evaluated the mechanism of BRG1 in peritoneal mesothelial cell senescence and peritoneal fibrosis using BRG1 knockdown mice, primary peritoneal mesothelial cells and human peritoneal samples from PD patients. The augmentation of BRG1 expression accelerated peritoneal mesothelial cell senescence, which attributed to mitochondrial dysfunction and mitophagy inhibition. Mitophagy activator salidroside rescued fibrotic responses and cellular senescence induced by BRG1. Mechanistically, BRG1 was recruited to oxidation resistance 1 (OXR1) promoter, where it suppressed transcription of OXR1 through interacting with forkhead box protein p2. Inhibition of OXR1 abrogated the improvement of BRG1 deficiency in mitophagy, fibrotic responses and cellular senescence. In a mouse PD model, BRG1 knockdown restored mitophagy, alleviated senescence and ameliorated peritoneal fibrosis. More importantly, the elevation level of BRG1 in human PD was associated with PD duration and D/P creatinine values. In conclusion, BRG1 accelerates mesothelial cell senescence and peritoneal fibrosis by inhibiting mitophagy through repression of OXR1. This indicates that modulating BRG1-OXR1-mitophagy signaling may represent an effective treatment for PD-related peritoneal fibrosis.

The disruptor of telomeric silencing 1-like (DOT1L) promotes peritoneal fibrosis through the upregulation and activation of protein tyrosine kinases.

The disruptor of telomeric silencing 1-like (DOT1L), a specific histone methyltransferase that catalyzed methylation of histone H3 on lysine 79, was associated with the pathogenesis of many diseases, but its role in peritoneal fibrosis remained unexplored. Here, we examined the role of DOT1L in the expression and activation of protein tyrosine kinases and development of peritoneal fibrosis. We found that a significant rise of DOT1L expression in the fibrotic peritoneum tissues from long-term PD patients and mice. Inhibition of DOT1L significantly attenuated the profibrotic phenotypic differentiation of mesothelial cells and macrophages, and alleviated peritoneal fibrosis. Mechanistically, RNA sequencing and proteomic analysis indicated that DOT1L was mainly involved in the processes of protein tyrosine kinase binding and extracellular matrix structural constituent in the peritoneum. Chromatin immunoprecipitation (ChIP) showed that intranuclear DOT1L guided H3K79me2 to upregulate EGFR in mesothelial cells and JAK3 in macrophages. Immunoprecipitation and immunofluorescence showed that extranuclear DOT1L could interact with EGFR and JAK3, and maintain the activated signaling pathways. In summary, DOT1L promoted the expression and activation of tyrosine kinases (EGFR in mesothelial cells and JAK3 in macrophages), promoting cells differentiate into profibrotic phenotype and thus peritoneal fibrosis. We provide the novel mechanism of dialysis-related peritoneal fibrosis (PF) and the new targets for clinical drug development. DOT1L inhibitor had the PF therapeutic potential.

Novel Peritoneal Sclerosis Rat Model Developed by Administration of Bleomycin and Lansoprazole.

In our preliminary experiment, peritoneal sclerosis likely induced by peritoneal dialysis was unexpectedly observed in the livers of rats given bleomycin and lansoprazole. We examined whether this peritoneal thickening around the liver was time-dependently induced by administration of both drugs. Male Wistar rats were injected with bleomycin and/or lansoprazole for 2 or 4 weeks. The 3YB-1 cell line derived from rat fibroblasts was treated by bleomycin and/or lansoprazole for 24 h. The administration of both drugs together, but not individually, thickened the peritoneal tissue around the liver. There was accumulation of collagen fibers, macrophages, and eosinophils under mesothelial cells. Expressions of Col1a1, Mcp1 and Mcp3 genes were increased in the peritoneal tissue around the liver and in 3YB-1 cells by the administration of both drugs together, and Opn genes had increased expressions in this tissue and 3YB-1 cells. Mesothelial cells indicated immunoreactivity against both cytokeratin, a mesothelial cell marker, and αSMA, a fibroblast marker, around the livers of rats given both drugs. Administration of both drugs induced the migration of macrophages and eosinophils and induced fibrosis associated with the possible activation of fibroblasts and the possible promotion of the mesothelial-mesenchymal transition. This might become a novel model of peritoneal sclerosis for peritoneal dialysis.

Matrix metalloproteinase-10 deficiency has protective effects against peritoneal inflammation and fibrosis via transcription factor NFκΒ pathway inhibition.

One of the most common causes of discontinued peritoneal dialysis is impaired peritoneal function. However, its molecular mechanisms remain unclear. Previously, by microarray analysis of mouse peritoneum, we showed that MMP (matrix metalloproteinase)-10 expression is significantly increased in mice with peritoneal fibrosis, but its function remains unknown. Chlorhexidine gluconate (CG) was intraperitoneally injected to wild-type and MMP-10 knockout mice to induce fibrosis to elucidate the role of MMP-10 on peritoneal injury. We also examined function of peritoneal macrophages and mesothelial cells obtained from wild-type and MMP-10 knockout mice, MMP-10-overexpressing macrophage-like RAW 264.7 cells and MeT-5A mesothelial cells, investigated MMP-10 expression on peritoneal biopsy specimens, and the association between serum proMMP-10 and peritoneal solute transfer rates determined by peritoneal equilibration test on patients. MMP-10 was expressed in cells positive for WT1, a mesothelial marker, and for MAC-2, a macrophage marker, in the thickened peritoneum of both mice and patients. Serum proMMP-10 levels were well correlated with peritoneal solute transfer rates. Peritoneal fibrosis, inflammation, and high peritoneal solute transfer rates induced by CG were all ameliorated by MMP-10 deletion, with reduction of CD31-positive vessels and VEGF-A-positive cells. Expression of inflammatory mediators and phosphorylation of NFκΒ subunit p65 at S536 were suppressed in both MMP-10 knockout macrophages and mesothelial cells in response to lipopolysaccharide stimulation. Overexpression of MMP-10 in RAW 264.7 and MeT-5A cells upregulated pro-inflammatory cytokines with phosphorylation of NFκΒ subunit p65. Thus, our results suggest that inflammatory responses induced by MMP-10 are mediated through the NFκΒ pathway, and that systemic deletion of MMP-10 ameliorates peritoneal inflammation and fibrosis caused by NFκΒ activation of peritoneal macrophages and mesothelial cells.

Exosomal lnc-CDHR derived from human umbilical cord mesenchymal stem cells attenuates peritoneal epithelial-mesenchymal transition through AKT/FOXO pathway.

OBJECTIVE: Chronic stimulation of peritoneal dialysis (PD) fluid leads to the epithelial-mesenchymal transformation (EMT) of mesothelial cells, peritoneal fibrosis (PF), and ultimately ultrafiltration failure. Some studies have proposed that mesenchymal stem cells (MSCs) can alleviate PF. This study aimed to investigate whether the exosomes from human umbilical cord MSCs (hUMSCs) could alleviate peritoneal EMT. METHODS: Human peritoneal mesothelial cell line (HMrSV5) were treated with high glucose (HG) for 48 hours to induce the peritoneal EMT model. An inverted fluorescence microscope was used to observe the internalization of exosomes derived from hUMSCs (hUMSC-Exos). Western blot and real-time PCR were used to evaluate the expression of α-SMA, Vimentin, E-cadherin, PTEN, and AKT/FOXO3a. The relationships of lncRNA CDHR and miR-3149, miR-3149 and PTEN were detected by dual luciferase reporter gene assay. RESULTS: Compared with HG-induced HMrSV5, E-cadherin and PTEN levels significantly increased whereas α-SMA and Vimentin levels significantly decreased after treatment of hUMSC-CM and hUMSC-Exos (P < 0.05). An inverted fluorescence microscope showed HMrSV5 can absorb exosomes to alleviate EMT. Furthermore, exosomes extracted from lnc-CDHR siRNA-transfected hUMSCs can't ameliorate HMrSV5 EMT. Moreover, both CDHR overexpressed and miR-3149 inhibitor in HG-induced HMrSV5 alleviated the expression of α-SMA, and Vimentin, and increased the expression of E-cadherin and PTEN, and AKT/FOXO3a. A rescue experiment showed that CDHR overexpressed expression was repressed by miR-3149 in the HG-induced peritoneal EMT model. CONCLUSIONS: Exosomal lnc-CDHR derived from hUMSCs may competitively bind to miR-3149 to regulate suppression on target PTEN genes and alleviate EMT of HMrSV5 through AKT/FOXO pathway.

Galectin-1 promotes gastric cancer peritoneal metastasis through peritoneal fibrosis.

BACKGROUND: Peritoneal metastasis is one of the main causes of death in patients with gastric cancer (GC). Galectin-1 regulates various undesirable biological behaviors in GC and may be key in GC peritoneal metastasis. METHODS: In this study, we elucidated the regulatory role of galectin-1 in GC cell peritoneal metastasis. GC and peritoneal tissues underwent hematoxylin-eosin (HE), immunohistochemical (IHC), and Masson trichrome staining to analyze the difference in galectin-1 expression and peritoneal collagen deposition in different GC clinical stages. The regulatory role of galectin-1 in GC cell adhesion to mesenchymal cells and in collagen expression was determined using HMrSV5 human peritoneal mesothelial cells (HPMCs). Collagen and corresponding mRNA expression were detected with western blotting and reverse transcription PCR, respectively. The promoting effect of galectin-1 on GC peritoneal metastasis was verified in vivo. Collagen deposition and collagen I, collagen III, and fibronectin 1 (FN1) expression in the peritoneum of the animal models were detected by Masson trichrome and IHC staining. RESULTS: Galectin-1 and collagen deposition in the peritoneal tissues was correlated with GC clinical staging and were positively correlated. Galectin-1 enhanced the ability of GC cells to adhere to the HMrSV5 cells by promoting collagen I, collagen III, and FN1 expression. The in vivo experiments confirmed that galectin-1 promoted GC peritoneal metastasis by promoting peritoneal collagen deposition. CONCLUSION: Galectin-1-induced peritoneal fibrosis may create a favorable environment for GC cell peritoneal metastasis.

Endogenously produced hyaluronan contributes to the regulation of peritoneal adhesion development.

Peritoneal adhesions are postsurgical fibrotic complications connected to peritoneal inflammation. The exact mechanism of development is unknown; however, an important role is attributed to activated mesothelial cells (MCs) overproducing macromolecules of extracellular matrix (ECM), including hyaluronic acid (HA). It was suggested that endogenously-produced HA contributes to the regulation of different fibrosis-related pathologies. However, little is known about the role of altered HA production in peritoneal fibrosis. We focused on the consequences of the increased turnover of HA in the murine model of peritoneal adhesions. Changes of HA metabolism were observed in early phases of peritoneal adhesion development in vivo. To study the mechanism, human MCs MeT-5A and murine MCs isolated from the peritoneum of healthy mice were pro-fibrotically activated by transforming growth factor ß (TGFß), and the production of HA was attenuated by two modulators of carbohydrate metabolism, 4-methylumbelliferone (4-MU) and 2-deoxyglucose (2-DG). The attenuation of HA production was mediated by upregulation of HAS2 and downregulation of HYAL2 and connected to the lower expression of pro-fibrotic markers, including fibronectin and α-smooth muscle actin (αSMA). Moreover, the inclination of MCs to form fibrotic clusters was also downregulated, particularly in 2-DG-treated cells. The effects of 2-DG, but not 4-MU, were connected to changes in cellular metabolism. Importantly, the inhibition of AKT phosphorylation was observed after the use of both HA production inhibitors. In summary, we identified endogenous HA as an important regulator of peritoneal fibrosis, not just a passive player during this pathological process.

Knockdown of AK142426 suppresses M2 macrophage polarization and inflammation in peritoneal fibrosis via binding to c-Jun.

BACKGROUND: Peritoneal fibrosis is a common complication of peritoneal dialysis, which may lead to ultrafiltration failure and ultimately treatment discontinuation. LncRNAs participate in many biological processes during tumorigenesis. We investigated the role of AK142426 in peritoneal fibrosis. METHODS: The AK142426 level in peritoneal dialysis (PD) fluid was detected by quantitative real-time-PCR assay. The M2 macrophage distribution was determined by flow cytometry. The inflammatory cytokines of TNF-α and TGF-ß1 were measured by ELISA assay. The direct interaction between AK142426 and c-Jun was evaluated by RNA pull-down assay. In addition, the c-Jun and fibrosis related proteins were assessed by western blot analysis. RESULTS: The PD-induced peritoneal fibrosis mouse model was successfully established. More importantly, PD treatment induced M2 macrophage polarization and the inflammation in PD fluid, which might be associated with exosome transmission. Fortunately, AK142426 was observed to be upregulated in PD fluid. Mechanically, knockdown of AK142426 suppressed M2 macrophage polarization and inflammation. Furthermore, AK142426 could upregulate c-Jun through binding c-Jun protein. In rescue experiments, overexpression of c-Jun could partially abolish the inhibitory effect of sh-AK142426 on the activation of M2 macrophages and inflammation. Consistently, knockdown of AK142426 alleviated peritoneal fibrosis in vivo. CONCLUSIONS: This study demonstrated that knockdown of AK142426 suppressed M2 macrophage polarization and inflammation in peritoneal fibrosis via binding to c-Jun, suggesting that AK142426 might be a promising therapeutic target for patients of peritoneal fibrosis.

The Transfer of the Hepatocyte Growth Factor Gene by Macrophages Ameliorates the Progression of Peritoneal Fibrosis in Mice.

Growing evidence indicates that hepatocyte growth factor (HGF) possesses potent antifibrotic activity. Furthermore, macrophages migrate to inflamed sites and have been linked to the progression of fibrosis. In this study, we utilized macrophages as vehicles to express and deliver the HGF gene and investigated whether macrophages carrying the HGF expression vector (HGF-M) could suppress peritoneal fibrosis development in mice. We obtained macrophages from the peritoneal cavity of mice stimulated with 3% thioglycollate and used cationized gelatin microspheres (CGMs) to produce HGF expression vector-gelatin complexes. Macrophages phagocytosed these CGMs, and gene transfer into macrophages was confirmed in vitro. Peritoneal fibrosis was induced by intraperitoneal injection of chlorhexidine gluconate (CG) for three weeks; seven days after the first CG injection, HGF-M was administered intravenously. Transplantation of HGF-M significantly suppressed submesothelial thickening and reduced type III collagen expression. Moreover, in the HGF-M-treated group, the number of α-smooth muscle actin- and TGF-ß-positive cells were significantly lower in the peritoneum, and ultrafiltration was preserved. Our results indicated that the transplantation of HGF-M prevented the progression of peritoneal fibrosis and indicated that this novel gene therapy using macrophages may have potential for treating peritoneal fibrosis.

TMT quantitative proteomics and network pharmacology reveal the mechanism by which asiaticoside regulates the JAK2/STAT3 signaling pathway to inhibit peritoneal fibrosis.

ETHNOPHARMACOLOGICAL RELEVANCE: Traditional Chinese medicine, Centella asiatica (L.) Urb., has been extensively utilized in clinics to treat a variety of fibrotic disorders. Asiaticoside (ASI), as an important active ingredient, has attracted much attention in this field. However, the effect of ASI on peritoneal fibrosis (PF) is still unclear. Therefore, we evaluated the benefits of ASI for PF and mesothelial-mesenchymal transition (MMT) and revealed the underlying mechanisms. AIM OF STUDY: The objective of this investigation was to anticipate the potential molecular mechanism of ASI against peritoneal mesothelial cells (PMCs) MMT employing proteomics and network pharmacology, and to confirm it using in vivo and in vitro studies. MATERIALS AND METHODS: The mesentery of peritoneal fibrosis mice and normal mice were analyzed quantitatively for proteins that were differentially expressed using a technique tandem mass tag (TMT). Next, the core target genes of ASI against PF were screened through network pharmacology analysis, and PPI and C-P‒T networks were constructed by Cytoscape Version 3.7.2. According to the findings of a GO and KEGG enrichment analysis of differential proteins and core target genes, the signaling pathway with a high correlation degree was selected as the key signaling pathway of ASI inhibiting the PMCs MMT for further molecular docking analysis and experimental verification. RESULTS: TMT-based quantitative proteome analysis revealed the identification of 5727 proteins, of which 70 were downregulated and 178 were upregulated. Among them, the levels of STAT1, STAT2, and STAT3 in the mesentery of mice with peritoneal fibrosis were considerably lower than in the control group, indicating a role for the STAT family in the pathogenesis of peritoneal fibrosis. Then, a total of 98 ASI-PF-related targets were identified by network pharmacology analysis. JAK2 is one of the top 10 core target genes representing a potential therapeutic target. JAK/STAT signaling may represent a core pathway mediating PF effects by ASI. Molecular docking studies showed that ASI had the potential to interact favorably with target genes involved in the JAK/STAT signaling pathway, such as JAK2 and STAT3. The experimental results showed that ASI could significantly alleviate Chlorhexidine Gluconate (CG)-induced peritoneal histopathological changes and increase JAK2 and STAT3 phosphorylation levels. In TGF-ß1-stimulated HMrSV5 cells, E-cadherin expression levels were dramatically reduced whereas Vimentin, p-JAK2, α-SMA, and p-STAT3 expression levels were considerably increased. ASI inhibited the TGF-ß1-induced HMrSV5 cell MMT, decreased the activation of JAK2/STAT3 signaling, and increased the nuclear translocation of p-STAT3, which was consistent with the effect of the JAK2/STAT3 pathway inhibitor AG490. CONCLUSION: ASI can inhibit PMCs MMT and alleviate PF by regulating the JAK2/STAT3 signaling pathway.

Bone Marrow Mesenchymal Stem Cell-Derived Exosomes Alleviate Peritoneal Dialysis-Associated Peritoneal Injury.

Peritoneal fibrosis is a critical sequela that limits the application of peritoneal dialysis (PD). This study explored the role and mechanism of bone marrow mesenchymal stem cell-derived exosomes (BMSC-Exos) in preventing PD-associated peritoneal injury. C57BL/6 mice were randomized into three groups: a control (saline), peritoneal injury [2.5% glucose peritoneal dialysate + lipopolysaccharide (LPS)], and peritoneal injury + exosome group. After 6 weeks, mice were dissected, and the parietal peritoneum was collected. The level of peritoneal structural and functional damage was assessed. Additionally, transcriptome analysis of the peritoneum and miRNA sequencing on BMSC-Exos were performed. The parietal peritoneum had significantly thickened, and peritoneal function was impaired in the peritoneal injury group. Peritoneal structural and functional damage was significantly reduced after exosome treatment, while peritoneal inflammation, fibrosis, angiogenesis, and mesothelial damage significantly increased. Transcriptomic analysis showed that the BMSC-Exos affected the cell cycle process, cell differentiation, and inflammatory response regulation. Significant pathways in the exosome group were enriched by inflammation, immune response, and cell differentiation, which constitute a molecular network that regulates the peritoneal protective mechanism. Additionally, inflammatory factors (TNF-α, IL-1ß), fibrosis markers (α-SMA, collagen-III, fibronectin), profibrotic cytokines (TGF-ß1), and angiogenesis-related factor (VEGF) were downregulated at the mRNA and protein levels through BMSC-Exos treatment. BMSC-Exos treatment can prevent peritoneal injury by inhibiting peritoneal fibrosis, inflammation, and angiogenesis, showing a multitarget regulatory effect. Therefore, BMSC-Exos therapy might be a new therapeutic strategy for treating peritoneal injury.

Activated protein C inhibits mesothelial-to-mesenchymal transition in experimental peritoneal fibrosis.

BACKGROUND: In addition to its anticoagulant function in downregulating thrombin generation, activated protein C (APC) evokes pleiotropic cytoprotective signaling activities when it binds to endothelial protein C receptor (EPCR) to activate protease-activated receptor 1 (PAR1) in endothelial cells. OBJECTIVES: To investigate the protective effect of APC in a chlorhexidine gluconate (CG)-induced peritoneal fibrosis model. METHODS: Peritoneal fibrosis was induced in wild-type as well as EPCR- and PAR1-deficient mice via daily injection of CG (0.2 mL of 0.1% CG in 15% ethanol and 85% saline) for 21 days with or without concomitant injection of recombinant human APC derivatives (50 µg/kg of bodyweight). The expression of proinflammatory cytokines and profibrotic markers as well as collagen deposition were analyzed using established methods. RESULTS: CG significantly upregulated the expression of transforming growth factor-ß1 in peritoneal tissues, which culminated in the deposition of excessive extracellular matrix proteins, thickening of the peritoneal membrane, and mesothelial-to-mesenchymal transition in damaged tissues. APC potently inhibited CG-induced peritoneal fibrosis and downregulated the expression of proinflammatory cytokines, collagen deposition, Smad3 phosphorylation, and markers of mesothelial-to-mesenchymal transition (α-smooth muscle actin, vimentin, and N-cadherin). APC also inhibited transforming growth factor-ß1-mediated upregulation of α-smooth muscle actin, Smad3, and fibronectin in human primary mesothelial cells. Employing signaling-selective and anticoagulant-selective variants of APC and mutant mice deficient for either EPCR or PAR1, we demonstrated that the EPCR-dependent signaling function of APC through PAR1 activation was primarily responsible for its antifibrotic activity in the CG-induced peritoneal fibrosis model. CONCLUSION: APC and signaling-selective variants of APC may have therapeutic potential for preventing or treating pathologies associated with peritoneal fibrosis.

miR-128-3p inhibits high-glucose-induced peritoneal mesothelial cells fibrosis via PAK2/SyK/TGF-ß1 axis.

AIM: To elucidate the mechanism of miR-128-3p in peritoneal fibrosis (PF). METHODS: Peritoneal mesothelial cells (PMCs) were dealt with high glucose (HG) for 3 days. The expressions of miR-128-3p, p21-activated kinase 2 (PAK2), spleen tyrosine kinase (SyK), and transforming growth factor-ß1 (TGF-ß1) were detected with quantitative real-time reverse transcription polymerase chain reaction. The levels of IL-1ß, TNF-α, IL-6, and monocyte chemotactic protein-1 in supernatant were measured by ELISA. Proteins of TGF-ß1, SyK, PAK2, α-SMA, collagen I, vimentin, ERK/AP-1, and IκBα/NF-κB pathway related proteins were measured by Western blot. The correlation between miR-128-3p and PAK2 was found by bioinformatics analysis and luciferase reporter gene analysis. RESULTS: miR-128-3p was decreased while PAK2, SyK, and TGF-ß1 were increased in HG-induced PMCs. Moreover, miR-128-3p inhibited HG-induced fibrosis and inflammation in PMCs by targeting PAK2. PAK2 activated SyK, which induced TGF-ß1 expression through ERK/AP-1 and IκBα/NF-κB pathways to promote HG-induced fibrosis of PMCs. CONCLUSION: miR-128-3p inhibited HG-induced PMCs fibrosis via PAK2/SyK/TGF-ß1 axis.

C allele in transforming growth factor-ß1 rs1800471 gene polymorphisms might indicate a protective feature in encapsulating peritoneal sclerosis development.

INTRODUCTION: Peritoneal fibrosis may progress in peritoneal dialysis (PD) patients to a fatal clinical condition called encapsulating peritoneal sclerosis (EPS). Transforming growth factor (TGF)-ß plays a pivotal role in the pathogenesis of peritoneal fibrosis. We aimed to investigate the association among polymorphisms in the gene encoding TGF-ß1, which were -509C/T (rs1800469), +869T/C (rs1982073), and +915G/C (rs1800471) in EPS patients. METHODS: A total of 16 PD patients who were clinically and radiologically diagnosed with EPS were enrolled and 22 age- and gender-matched PD patients were selected as the non-EPS group. RESULTS: G allele frequency at the rs1800471 gene polymorphism was significantly higher in the EPS group than non-EPS group (p = 0.005). Interestingly, the non-EPS group patients had CC or CG polymorphisms. CONCLUSION: C allele in TGF-ß1 rs1800471 gene polymorphisms might indicate a protective feature in EPS development. Knowing the presence of polymorphism may be effective in selecting renal replacement therapy in patients.

Peritoneal effluent MicroRNA profile for detection of encapsulating peritoneal sclerosis.

BACKGROUND: Encapsulating peritoneal sclerosis (EPS) is a catastrophic complication of peritoneal dialysis (PD) with high mortality. Our aim is to develop a novel noninvasive microRNA (miRNA) test for EPS. METHODS: We collected 142 PD effluents (EPS: 62 and non-EPS:80). MiRNA profiles of PD effluents were examined by a high-throughput real-time polymerase chain reaction (PCR) array to first screen. Candidate miRNAs were verified by single real-time PCR. The model for EPS prediction was evaluated by multiple logistic regression and machine learning. RESULTS: Seven candidate miRNAs were identified from the screening of PCR-array of 377 miRNAs. The top five area under the curve (AUC) values with 5 miRNA-ratios were selected using 127 samples (EPS: 56 vs non-EPS: 71) to produce a receiver operating characteristic curve. After considering clinical characteristics and 5 miRNA-ratios, the accuracies of the machine learning model of Random Forest and multiple logistic regression were boosted to AUC 0.97 and 0.99, respectively. Furthermore, the pathway analysis of miRNA associated targeting genes and miRNA-compound interaction network revealed that these five miRNAs played the roles in TGF-ß signaling pathway. CONCLUSION: The model-based miRNA expressions in PD effluents may help determine the probability of EPS and provide further therapeutic opinion for EPS.