Pilar Sandoval

Tissue trauma initiates inflammation that can lead to fibrotic complications such as postoperative peritoneal adhesions, which contribute to chronic pain, infertility, and bowel obstruction. Despite their prevalence and impact, effective interventions to prevent adhesion formation remain limited. In this study, we evaluated a sprayable extracellular matrix (ECM) hydrogel as a barrier to protect healing tissues and reduce adhesion formation after abdominal surgery. In both mouse and rabbit models of colorectal and gynecologic procedures, ECM hydrogel application resulted in a substantial reduction in adhesion severity. Mechanistic studies demonstrated that the hydrogel promotes preservation or restoration of the mesothelial lining while modulating early local inflammation. Treated tissues exhibited reduced expression of inflammatory cytokines, including IL-1β, and maintained an intact mesothelial surface with fewer activated myofibroblasts compared with synthetic hydrogel and controls. Immunohistochemical analysis, transcriptomic profiling of mesothelial cells, and in vitro mechanical stretch experiments revealed that the ECM hydrogel mitigates mesothelial-to-mesenchymal transition. These findings suggest that the hydrogel not only provides a physical barrier but also serves as a biological modulator, shielding tissue from mechanical and inflammatory cues that drive adhesion formation. Overall, this study identifies a dual-function, biologically active ECM hydrogel capable of protecting healing tissues and reducing adhesion development in preclinical surgical models. These results support the potential of ECM hydrogel as a clinically translatable, biocompatible strategy for improving postsurgical healing outcomes and reducing adhesion-related complications.

Carcinoma-associated fibroblasts (CAFs) are highly accumulated in the tumor-surrounding stroma of primary epithelial ovarian cancer (OC). CAFs exert important functions for the vascularization, growth, and progression of OC cells. However, the origin of CAFs in primary OC had not yet been studied, and they were assumed to arise from the activation of resident fibroblasts. Here, we compared CAFs in the ovary to CAFs found in peritoneal metastases from patients with advanced OC. Our findings show that CAFs from primary tumors and peritoneal metastases share the expression of mesothelial markers. Therefore, similar to peritoneal carcinomatosis, CAFs in primary ovarian carcinomas may originate from mesothelial cells via a mesothelial-to-mesenchymal transition. The detection of mesothelial-derived CAFs in tumors confined to the ovary and identification of biomarkers could be the key to the early detection of OC and peritoneal spread.

: Carcinoma-associated fibroblasts (CAFs) are highly accumulated in the tumor surrounding stroma of primary epithelial ovarian cancer (OC). CAFs exert important functions for the vascularization, growth and progression of ovarian tumor cells. However, no attention has been shown to their origin so far. It has been mainly assumed that CAFs in primary OC arise from the activation of resident fibroblasts. Here, we compare CAFs with ovarian location to CAFs found in peritoneal implants from patients with advanced OC. Our findings show that CAFs from primary tumors and peritoneal metastases share the expression of mesothelial-related markers. Therefore, as in peritoneal carcinomatosis, CAFs in primary ovarian carcinomas could be originated via a mesothelia-to-mesenchymal transition (MMT) process. The detection of mesothelial-derived CAFs in tumors confined to the ovary and associated biomarkers could be the key to early detection of peritoneal spread in affected patients.

Ovarian carcinomatosis is characterized by the accumulation of carcinoma‐associated mesothelial cells (CAMs) in the peritoneal stroma and mainly originates through a mesothelial‐to‐mesenchymal transition (MMT) process. MMT has been proposed as a therapeutic target for peritoneal metastasis. Most ovarian cancer (OC) patients present at diagnosis with peritoneal seeding, which makes tumor progression control difficult by MMT modulation. An alternative approach is to use antibody–drug conjugates (ADCs) targeted directly to attack CAMs. This strategy could represent the cornerstone of precision‐based medicine for peritoneal carcinomatosis. Here, we performed complete transcriptome analyses of ascitic fluid‐isolated CAMs in advanced OC patients with primary‐, high‐, and low‐grade, serous subtypes and following neoadjuvant chemotherapy. Our findings suggest that both cancer biological aggressiveness and chemotherapy‐induced tumor mass reduction reflect the MMT‐associated changes that take place in the tumor surrounding microenvironment. Accordingly, MMT‐related genes, including fibroblast activation protein (FAP), mannose receptor C type 2 (MRC2), interleukin‐11 receptor alpha (IL11RA), myristoylated alanine‐rich C‐kinase substrate (MARCKS), and sulfatase‐1 (SULF1), were identified as specific actionable targets in CAMs of OC patients, which is a crucial step in the de novo design of ADCs. These cell surface target receptors were also validated in peritoneal CAMs of colorectal cancer peritoneal implants, indicating that ADC‐based treatment could extend to other abdominal tumors that show peritoneal colonization. As proof of concept, a FAP‐targeted ADC reduced tumor growth in an OC xenograft mouse model with peritoneal metastasis‐associated fibroblasts. In summary, we propose MMT as a potential source of ADC‐based therapeutic targets for peritoneal carcinomatosis. © 2023 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of The Pathological Society of Great Britain and Ireland.

Editorial: Molecular mechanisms and new therapeutic targets in epithelial to mesenchymal transition (EMT) and fibrosis, volume II

Most patients with ovarian cancer (OvCA) present peritoneal disseminated disease at the time of diagnosis. During peritoneal metastasis, cancer cells detach from the primary tumor and disseminate through the intraperitoneal fluid. The peritoneal mesothelial cell (PMC) monolayer that lines the abdominal cavity is the first barrier encountered by OvCA cells. Subsequent progression of tumors through the peritoneum leads to the accumulation into the peritoneal stroma of a sizeable population of carcinoma-associated fibroblasts (CAFs), which is mainly originated from a mesothelial-to-mesenchymal transition (MMT) process. A common characteristic of OvCA patients is the intraperitoneal accumulation of ascitic fluid, which is composed of cytokines, chemokines, growth factors, miRNAs, and proteins contained in exosomes, as well as tumor and mesothelial suspended cells, among other components that vary in proportion between patients. Exosomes are small extracellular vesicles that have been shown to mediate peritoneal metastasis by educating a pre-metastatic niche, promoting the accumulation of CAFs via MMT, and inducing tumor growth and chemoresistance. This review summarizes and discusses the pivotal role of exosomes and MMT as mediators of OvCA peritoneal colonization and as emerging diagnostic and therapeutic targets.

Peritoneal hyalinizing vasculopathy (PHV) represents the cornerstone of long-term peritoneal dialysis (PD), and especially characterizes patients associated with encapsulating peritoneal sclerosis. However, the mechanisms of PHV development remain unknown. A cross sectional study was performed in 100 non-selected peritoneal biopsies of PD patients. Clinical data were collected and lesions were evaluated by immunohistochemistry. In selected biopsies a microRNA (miRNA)-sequencing analysis was performed. Only fifteen patients (15%) showed PHV at different degrees. PHV prevalence was significantly lower among patients using PD fluids containing low glucose degradation products (GDP) (5.9% vs. 24.5%), angiotensin converting enzyme inhibitors (ACEIs) (7.5% vs. 23.4%), statins (6.5% vs. 22.6%) or presenting residual renal function, suggesting the existence of several PHV protective factors. Peritoneal biopsies from PHV samples showed loss of endothelial markers and induction of mesenchymal proteins, associated with collagen IV accumulation and wide reduplication of the basement membrane. Moreover, co-expression of endothelial and mesenchymal markers, as well as TGF-β1/Smad3 signaling activation were found in PHV biopsies. These findings suggest that an endothelial-to-mesenchymal transition (EndMT) process was taking place. Additionally, significantly higher levels of miR-7641 were observed in severe PHV compared to non-PHV peritoneal biopsies. Peritoneal damage by GDPs induce miRNA deregulation and an EndMT process in submesothelial vessels, which could contribute to collagen IV accumulation and PHV.

During peritoneal metastasis, cancer cells spread from abdominal solid tumors, disseminate through the peritoneal fluid and attach to and invade through mesothelial cells (MCs) that line the peritoneum. Intestinal adenocarcinomas originating in the mucosa infiltrate the submucosa, muscle layer, and serosa in order to finally colonize the peritoneal cavity. However, the mechanism by which metastatic cells leave the primary tumor and reach the peritoneal cavity has not been previously described. Hence, we investigate whether MCs lining visceral peritoneum, through a mesothelial-to-mesenchymal transition (MMT), are a source of carcinoma-associated fibroblasts (CAFs), which could contribute to cancer progression toward the peritoneal cavity. CAFs detected in biopsies from patients with superficially invasive colorectal cancer differed from locally advanced tumors. An aberrant accumulation of myofibroblasts expressing mesothelial markers was found in the stroma of deeply infiltrative tumors located in the neighborhood of a frequently activated mesothelium. We suggest that MMT is a key event in the early stages of peritoneal dissemination.

Prostaglandin (PG) F _2α has been scarcely studied in cancer. We have identified a new role for PGF _2α in ovarian cancer, stimulating the production of TGFβ and the consequent induction of PMEPA1. We show that this induction increases cell plasticity and proliferation, enhancing tumor growth through PMEPA1. Thus, PMEPA1 overexpression in ovarian carcinoma cells, significantly increased cell proliferation rates, whereas PMEPA1 silencing decreased proliferation. In addition, PMEPA1 overexpression buffered TGFβ signaling, via reduction of SMAD-dependent signaling. PMEPA1 overexpressing cells acquired an epithelial morphology, associated to higher E-cadherin expression levels while β-catenin nuclear translocation was inhibited. Interestingly, in mouse xenografts, PMEPA1 overexpressing ovarian cells had a clear survival and proliferative advantage, resulting in higher metastatic capacity, while PMEPA1 silencing had the opposite effect. Furthermore, high PMEPA1 expression in a cohort of advanced ovarian cancer patients was observed, correlating with E-cadherin expression. Most importantly, high PMEPA1 mRNA levels were associated with lower patient survival. Significance: This work identifies Prostaglandin F _2α as an inducer, through NFAT, of TGFβ and together with this up-regulate PMEPA1, which is identified both as a drug target and as a prognostic biomarker in ovarian tumors, potentially useful in clinical practice.

Correction: Nebivolol, a β 1 -adrenergic blocker, protects from peritoneal membrane damage induced during peritoneal dialysis