Project description:Abdominal surgeries are lifesaving procedures but can be complicated by the formation of peritoneal adhesions, intra-abdominal scars that cause intestinal obstruction, pain, infertility, and significant health costs. Despite this burden, the mechanisms underlying adhesion formation remain unclear and no cure exists. Here, we show that contamination of gut microbes increases post-surgical adhesion formation. Using genetic lineage tracing we show that adhesion myofibroblasts arose from the mesothelium. This transformation was driven by epidermal growth factor receptor (EGFR) signaling. The EGFR ligands Amphiregulin and Heparin-binding Epidermal Growth Factor, were sufficient to induce these changes. Correspondingly, EGFR inhibition led to a significant reduction of adhesion formation in mice. Adhesions isolated from human patients were enriched in EGFR positive cells of mesothelial origin and human mesothelium showed an increase of mesothelial EGFR expression during bacterial peritonitis. In conclusion, bacterial contamination drives adhesion formation through mesothelial EGFR signaling. This mechanism may represent a therapeutic target for the prevention of adhesions after intra-abdominal surgery.
Project description:Peritoneal fibrosis is a major complication of long-term peritoneal dialysis (PD), leading to ultrafiltration failure and sometimes life threatening encapsulating peritoneal sclerosis. Fibrosis is driven by activated myofibroblasts that are derived, in part, from mesothelial-to-mesenchymal transition (MMT). We aimed to discover novel mediators of MMT and then experimentally exploit them to prevent peritoneal fibrosis. Using an antibody to HBME-1 and streptavidin nanobead technology, we first pioneered a novel method to purify rat mesothelial cells. After exposing mesothelial cells to transforming growth factor β1 (TGFβ1), we undertook RNAseq whole transcriptome analyses and outlined, the expression profile of sorted mesothelial cells at pre- and post- MMT.
Project description:Despite their emerging relevance to fully understand disease pathogenesis, we have as yet a poor understanding as to how biomechanical signals are integrated with specific biochemical pathways to determine cell behaviour. Mesothelial-to-mesenchymal transition (MMT) markers colocalized with TGF-beta1-dependent signalling and yes-associated protein (YAP) activation across biopsies from different pathologies exhibiting peritoneal fibrosis, supporting mechanotransduction as a central driving component of these class of fibrotic lesions and its crosstalk with specific signaling pathways. Transcriptome and proteome profiling of the response of mesothelial cells (MCs) to linear cyclic stretch revealed molecular changes compatible with bona fide MMT, which (i) overlapped with established YAP target gene subsets, and (ii) were largely dependent on endogenous TGF-beta1 signaling. Importantly, TGF-beta1 blockade blunts the transcriptional upregulation of the se gene signatures, but not the mechanical activation and nuclear translocation of YAP per se. We studied the role therein of caveolin-1 (Cav1), a plasma membrane mechanotransducer. Exposure of Cav1-deficient MCs to cyclic stretch led to a robust upregulation of MMT-related gene programs, which was blunted upon TGF-beta1 inhibition. Conversely, Cav1 depletion enhanced both TGF-beta1 and TGFBRI expression. Cav1 genetic deficiency exacerbated MMT and PA fibrosis in an experimental model of peritoneal ischaemic buttons. Taken together, these results support that Cav1-YAP/TAZ fine-tune the fibrotic response through the modulation of MMT, onto which TGF-beta1-dependent signaling coordinately converges. Our findings reveal a cooperation between biomechanical and biochemical signals in the triggering of MMT, representing a novel potential opportunity to intervene mechanically-induced disorders coursing with peritoneal fibrosis, such as post-surgical adhesions. This SuperSeries is composed of the SubSeries listed below.
Project description:Peritoneal dialysis (PD) is a successful renal replacement therapy for end-stage renal disease that effectively improves the quality of life. Long-term PD causes epithelial mesenchymal transformation (MMT) of peritoneal mesothelial cells, leading to peritoneal fibrosis which reduces the efficiency of PD. Macrophages are considered players in the onset and perpetuation of peritoneal injury. Yet, the mechanisms employed by macrophage-mesothelial cells communication to regulate peritoneal fibrosis are not fully elucidated resulting in lack of disease-modified drugs. This study analyzes the role of macrophage-mesothelial cell communication by intraperitoneal injection of macrophage derived exosomes in PD model rats. These results show that macrophages secrete exosomal miR-204-5p that directly targets Foxc1, leading to the activation of MMT in mesothelial cells. The data also shows that intraperitoneal injection of dissolved AS-IV can improve MMT by altering macrophage derived exosomal miRNAs. This study indicates that intercellular crosstalk between peritoneal macrophages and mesothelial cells is mediated by macrophage derived miR-204-5p-containing exosomes that control the MMT progression, providing AS-IV for prevention and treatment of PD induced peritoneal fibrosis. Our results demonstrate, for the first time, a novel role of the AS-IV on miR-204-5p/Foxc1/β-catenin axis in improving peritoneal fibrosis in vivo and vitro.
Project description:Peritoneal mesothelial cells are harmed by peritoneal dialysis fluids (PDF) used in renal replacement therapy with peritoneal dialysis. The mechanisms of the cellular damage are not yet described in detail. Primary human peritoneal mesothelial cells derived from omentum of five donors were independently exposed to peritoneal dialysis fluids. The extent of cell damage was assessed using lactate dehydrogenase (LDH) release in the cell culture supernatant and cells were lysed in order to extract mRNA and proteins. Transcriptional changes induced by PDF were analyzed using gene expression microarrays and changes of the proteome were analyzed using 2D-electrophoresis.
Project description:Peritoneal dialysis (PD) is an effective form of renal replacement therapy. A significant proportion of patients who initiate PD suffer from PD-related clinical complications, including peritoneal membrane damage, which may limit the duration of treatment. Mesothelial-to-mesenchymal transition (MMT) significantly contributes to the peritoneal dysfunction related to PD. Hence, we analyzed the genetic reprograming of the MMT-process with the aim to identify new biomarkers that may be tested in PD-patients. Microarray analysis revealed a partial overlapping of MMT induced in vitro and MMT of effluent-derived mesothelial cells (ex vivo), and that MMT, both in vitro and ex vivo, is mainly a repression process being higher the number of genes that are down-regulated than those that are induced. According to cellular morphology and the number of altered genes and pathways, the MMT ex vivo could be subdivided into two stages: early/epitheliod and advanced/non-epitheliod. We could demonstrate by RT-PCR array analysis that a number of genes differentially expressed in effluent-derived non-epitheliod cells also showed significant differential expression when comparing standard versus low-GDP PD fluids. Among the secreted proteins that are up-regulated along the MMT process thrombospondin-1 (TSP1), collagen-13 (COL13), vascular endothelial growth factor A (VEGFA), and gremlin-1 (GREM1) were selected to be measured in PD effluents. TSP1, COL13 and VEGFA, but not GREM1, showed significant differences between early and advanced stages of MMT, and their expression were associated with high peritoneal transport status. The results establish a proof of concept about the feasibility of MMT-associated secreted proteins as biomarkers in PD.
Project description:Peritoneal dialysis (PD) is an effective form of renal replacement therapy. A significant proportion of patients who initiate PD suffer from PD-related clinical complications, including peritoneal membrane damage, which may limit the duration of treatment. Mesothelial-to-mesenchymal transition (MMT) significantly contributes to the peritoneal dysfunction related to PD. Hence, we analyzed the genetic reprograming of the MMT-process with the aim to identify new biomarkers that may be tested in PD-patients. Microarray analysis revealed a partial overlapping of MMT induced in vitro and MMT of effluent-derived mesothelial cells (ex vivo), and that MMT, both in vitro and ex vivo, is mainly a repression process being higher the number of genes that are down-regulated than those that are induced. According to cellular morphology and the number of altered genes and pathways, the MMT ex vivo could be subdivided into two stages: early/epitheliod and advanced/non-epitheliod. We could demonstrate by RT-PCR array analysis that a number of genes differentially expressed in effluent-derived non-epitheliod cells also showed significant differential expression when comparing standard versus low-GDP PD fluids. Among the secreted proteins that are up-regulated along the MMT process thrombospondin-1 (TSP1), collagen-13 (COL13), vascular endothelial growth factor A (VEGFA), and gremlin-1 (GREM1) were selected to be measured in PD effluents. TSP1, COL13 and VEGFA, but not GREM1, showed significant differences between early and advanced stages of MMT, and their expression were associated with high peritoneal transport status. The results establish a proof of concept about the feasibility of MMT-associated secreted proteins as biomarkers in PD.
Project description:Peritoneal mesothelial cells are harmed by peritoneal dialysis fluids (PDF) used in renal replacement therapy with peritoneal dialysis. The mechanisms of the cellular damage are not yet described in detail. Primary human peritoneal mesothelial cells derived from omentum of five donors were independently exposed to peritoneal dialysis fluids (extended recovery time). The extent of cell damage was assessed using lactate dehydrogenase (LDH) release in the cell culture supernatant and cells were lysed in order to extract mRNA and proteins. Transcriptional changes induced by PDF were analyzed using gene expression microarrays and changes of the proteome were analyzed using 2D-electrophoresis.
Project description:Peritoneal mesothelial cells are harmed by peritoneal dialysis fluids (PDF) used in renal replacement therapy with peritoneal dialysis. The mechanisms of the cellular damage are not yet described in detail. Primary human peritoneal mesothelial cells derived from omentum of five donors were independently exposed to peritoneal dialysis fluids. The extent of cell damage was assessed using lactate dehydrogenase (LDH) release in the cell culture supernatant and cells were lysed in order to extract mRNA and proteins. Transcriptional changes induced by PDF were analyzed using gene expression microarrays and changes of the proteome were analyzed using 2D-electrophoresis.