Mesothelial Research Articles

Abstract 4135447: Demographics, Clinicopathological Outcomes and Comparative Survival Analysis of Pleural and Pericardial Mesothelioma; A Retrospective Population-Based Study

Background: Malignant mesothelioma (MM) is an aggressive and rare tumor of mesothelial cells that is strongly correlated with asbestos exposure. Due to its long latency period, MM is characterized by its poor prognosis. In this study, we primarily analyzed data for the clinicopathological analysis of malignant pleural mesothelioma with comparative overall survival (OS) and cancer-specific survival (CSS) with primary pericardial mesothelioma. Method: The data was collected from the Epidemiology and End Results (SEER) database, comprising 12,991 mesothelioma patients from 2000 to 2020. Results: A total of 12,991 cases of MM were extracted from the database, of which 99.55% were pleural and only 0.177% were pericardial. The median age was 74 years. Regarding gender, 80% of the patients were male. MM was found to be more common in older age (>65, 77%). 52% of the patients had a tumor size greater than 5 cm. The common histologic type was mesothelioma NOS (45%), followed by the epithelioid type (36%). The most common treatment modality was chemotherapy. Multivariate analysis showed better survival outcomes in younger, female patients undergoing combination therapies. Moreover, the histologic subtype, especially epithelioid mesothelioma, showed the overall best prognosis. Regarding comparative OS and CSS between pleural and pericardial mesothelioma, the 3-year OS of pleural mesothelioma was 11.2% (95% CI: 0.107 - 0.118) and for pericardial mesothelioma, the 3-year OS was 4.7% (95% CI: 0.007 - 0.317). Pleural mesothelioma had a 1-year CSS of 37.1% (95% CI: 0.343 - 0.401), and for pericardial mesothelioma, the CSS at 9 months was 28.6% (95% CI: 0.089 - 0.922), and all patients survived < 1 year in the cohort. Conclusion: Malignant mesothelioma is a rare and aggressive tumor. Pericardial mesothelioma has lower survival in comparison to pleural mesothelioma. Genomic analysis and including all ethnicities in future clinical trials will help in future personalized therapeutic approaches.

Effects of patient pleural effusion fluids on the BBSome components expression of human benign mesothelial cells.

Malignant pleural mesothelial cells are affected by the extracellular milieu while such data on benign cells are scarce. Benign cells sense the extracellular environment with the Primary Cilium (PC) and its molecular complex, the BBSome, is critical for this process. Here we aimed at assessing the changes in BBSome genes expression in ordinary 2D and spheroid 3D cell cultures after incubation with pleural effusion fluids (PF) of several etiologies. Benign human mesothelial cells MeT-5A were incubated with PF from patients with mesothelioma (Meso-PF), breast cancer (BrCa-PF), hemothorax (Hemo-PF) and congestive heart failure (CHF-PF). Gene expression of BBS1, 2, 4, 5, 7, 9, 18 was assessed by quantitative real-time PCR (qRT-PCR) to monitor PF-induced gene expression changes. MeT-5A cell migration using the PC-modulating drugs ammonium sulfate (AS) and lithium chloride (LC) during PF incubation was also determined. BBSome gene expression upon influence of BrCa-PF and Hemo-PF was more pronounced in 2D compared to 3D, inducing global changes in 2D. CHF-PF and Meso-PF also induced changes in 2D but not as many, while in all cases MeT-5A grown in 3D were more resistant to the effects of the PF. Meso-PF decreased 2D cell migration, while the disturbance of PC in all PF cases resulted in decreased cell migration. These data suggest distinct BBSome molecular profile changes in benign mesothelial cells exposed to malignant and benign PF, in each case, in both 2D and 3D. Cell migration is sensitive to drug disturbance with PC modulators in PF-exposed cells.

Long-term pulmonary repair in rat lungs after sublobar resection: electrocautery versus stapler methods.

We investigated and compared the long-term (6-month) histologic changes in a rat model of sublobar resection created using electrocautery or stapler techniques. Nine-week-old male rats were anesthetized and intubated; thoracotomy with sublobar resection was performed in the right middle lobe using electrocautery or stapler techniques. Histological examination was performed at 2, 4, 8, 12, and 24weeks post-surgery to assess long-term effects on lung tissue repair and morphologic changes. Lung expansion and alveolar epithelial cell proliferation were evaluated by measuring the mean linear intercept and counting the number of alveolar type I and II cells. The electrocautery group showed signs of lung self-repair at the resected area over time, with inflammatory cell infiltration followed by growth of vessels and bronchioles. Mesothelial cells covered the resected area by 2weeks; elastic fibers gradually connected from both sides by 24weeks. Lung expansion, measured by mean linear intercept, was initially small below the electrocautery resection area at 2weeks but recovered from 4 to 24weeks. The stapler group showed persistently small mean linear intercept over time. In the electrocautery group, the number of alveolar type II cells was higher just below the resection than in other areas from 2 to 24weeks, followed by alveolar type I cells (4 to 24weeks). The stapler group showed a transient alveolar type II cell increase at 2weeks. Compared to the stapler technique, electrocautery mayprovide advantages for postoperative lung repair by promoting lung expansion and alveolar epithelial cell proliferation.

Allicin Ameliorated High-glucose Peritoneal Dialysis Solution-induced Peritoneal Fibrosis in Rats via the JAK2/STAT3 Signaling Pathway.

Peritoneal fibrosis (PF) is one of the most serious complications of peritoneal dialysis (PD) and is the greatest obstacle to the clinical application of PD. Chinese herbal monomers have been effective in the prevention and treatment of PF. The aim of this study was to observe the effect of allicin on PF in rats induced by high glucose and to investigate its molecular mechanism of action. A rat model of PF was established by using a 4.25% glucose-based standard peritoneal dialysis solution. The degree of peritoneal pathological damage was assessed by Hematoxylin and eosin (H&E) staining. Peritoneal collagen deposition was detected by Masson's trichrome staining. The levels of Interleukin-6 (IL-6), Tumor necrosis factor-α (TNF-α), Interleukin-1β (IL-1β) and monocyte chemoattractant protein-1 (MCP-1) in the serum were measured by Enzyme Linked Immunosorbent Assay (ELISA). The expression levels of TGF-β, α-smooth muscle actin (α-SMA) and collagen I were examined by western blotting and immunohistochemistry. The protein expression levels and mRNA levels of E-cadherin, N-cadherin, vimentin, janus kinase 2 (JAK2) and signal transducer and activator of transcription 3 (STAT3) in peritoneal tissue were determined by western blotting and qRT-PCR. TGF-β1 stimulated human peritoneal mesothelial cells (HPMCs), and the cells were treated with allicin and the JAK2/STAT3 pathway activator colivelin alone or in combination. A cell counting kit-8 (CCK-8) assay was used to measure cell viability. The role of JAK2/STAT3 in the effects of allicin was confirmed via in vitro mechanistic research by western blotting, wound healing assays and Transwell assays. Allicin relieves the inflammatory response by downregulating the levels of IL-1β, IL-6, MCP-1 and TNF-α. Furthermore, allicin decreased the expression of TGF-β, α-SMA and collagen I. Allicin also alleviated epithelial-to-mesenchymal transition (EMT), as specifically manifested by increased E-cadherin and reduced N-cadherin and vimentin. Further studies revealed that allicin reduced the protein levels of JAK2, STAT3, p-JAK2, and p-STAT3. The results of the cellular experiments verified the above results. The ability of allicin to inhibit fibrosis and the EMT process was significantly attenuated after HPMCs were treated with colivelin. Taken together, these findings suggest that allicin inhibits inflammation and EMT, thereby improving PF, and this protective effect may be achieved by inhibiting the JAK2/STAT3 signaling pathway.

Eosinophil and B cell dynamics in the milky spots from Schistosoma mansoni-infected mice - Comparison with spleen and bone marrow, and extramedullary eosinopoiesis.

The milky spots are structures found in the omentum of humans and other vertebrates, representing a fraction of the lymphomyeloid tissue associated with the celom. They majorly consist of B lymphocytes, T lymphocytes, and macrophages. Also found in smaller quantities are mesothelial, stromal, dendritic, and rare mast cells. In an experimental model of Schistosoma mansoni infection, there is significant activation of the omentum and milky spots, which exhibit numerous eosinophils. Despite being described for many years, the complete profile of cells found in milky spots and their functions remains largely unexplored. Here, we evaluate the leukocyte populations of the milky spots in homeostasis and a murine model of Schistosoma mansoni infection. The histopathological characterizations, phenotypic profile analysis, and characterization of the eosinophilic potential of progenitors and precursors comparing the milky spots with the spleen and bone marrow showed significant activation of milky spots in infected mice, with changes in the profile over the analyzed times, showing signs of migration and activation of eosinophils, with local eosinopoiesis and maintenance of the eosinophilic population. In naive mice, B1a and B1b cells comprise only a small fraction of B lymphocytes. However, B1b cells expand significantly during infection, peaking at 60 DPI before stabilizing by 90 DPI. B1a cells also increase initially but decrease over time. The behavior of milky spots differs from other primary and secondary lymphoid organs, acting as a central lymphoid organ in cavity immunity.

Genistein inhibits HIF-1α and attenuates high glucose-induced peritoneal mesothelial-mesenchymal transition and fibrosis via the mTOR/OGT pathway

Peritoneal fibrosis has been linked to hypoxia-inducible factor 1-alpha (HIF-1α) as well as O-linked-N-acetylglucosaminylation (O-GlcNAcylation) in peritoneal dialysis (PD). Genistein, recognized for its HIF-1α inhibitory and antifibrotic effects, presents a potential intervention against peritoneal mesothelial-mesenchymal transition (MMT) as well as fibrosis in PD. This study employed human peritoneal mesothelial cells (HPMCs) together with adenine-induced chronic kidney disease (CKD) rats undergoing peritoneal dialysis to explore Genistein’s role in high glucose-induced peritoneal MMT and fibrosis. Our findings reveal that Genistein exerts anti-MMT and anti-fibrotic effects by inhibiting HIF-1α in HPMCs under high glucose conditions. Genistein inhibited O-GlcNAcylation status of HIF-1α through the mTOR/O-GlcNAc transferase (OGT) pathway, promoting its ubiquitination as well as the subsequent proteasomal degradation. In adenine-induced CKD rats undergoing peritoneal dialysis, Genistein suppressed the mTOR/OGT expression and reduced the abundance of O-GlcNAcylation along with HIF-1α in the peritoneum. Additionally, Genistein protected against increased peritoneal thickness, fibrosis, and angiogenesis, while improving peritoneal function. Based on our results, it could be inferred that Genistein might inhibit the abundance of HIF-1α via the mTOR/OGT pathway, thereby ameliorating MMT as well as fibrosis in PD.

Silent intruder: Identifying a testicular mass in the shadow of prostate carcinoma

Adenomatoid tumors of the testis are rare, benign neoplasms that arise from mesothelial cells. These tumors are usually asymptomatic and are often discovered incidentally during procedures or evaluations for other conditions. We present a case of 86 year male, in whom adenomatoid tumor was incidentally identified in the testis removed during an orchiectomy performed as part of the management for prostatic carcinoma.

An extremely Rare Case of Primary Peritoneal Mucinous Cystadenocarcinoma

Abstract Introduction/Objective Primary peritoneal mucinous adenocarcinoma is an extremely rare entity with no well- established treatment protocol. It occurs more commonly in females as compared to males which supports its less understood pathogenesis of arising from heterotopic ovarian tissue or mucinous metaplasia of mesothelial cells. Methods/Case Report We present a case of a 31-year-old female who presented with right flank pain after a fall. On imaging studies, a cyst measuring 11.4 x 9.6 x 8.8 cm with an enhancing mural nodule was identified in abdomen (Figure 1). Patient underwent exploratory laparotomy. We received 402.1 grams, 12.5 x 10.0 x 8.0 cm cystic mass. Cut surface showed an unilocular cyst filled with seromucinous fluid and 4.0 x 2.5 x 1.7 cm friable excrescences. Histologic examination showed an adenocarcinoma arising from background mucinous cystadenoma. The tumor cells were positive for AE1/AE3, CK7, CK20, villin (focal), PAX8 (focal), p53 (wild-type) and negative for WT-1, AMACR, CDX-2, TTF-1, GATA-3, inhibin and calretinin. ER and PR immunostains were positive in the ovarian-type stroma in the background mucinous cystadenoma. As the radiology work-up was negative for any other tumor in the pelvis or other sites, the diagnosis of primary peritoneal cystadenocarcinoma was rendered. Molecular analysis showed presence of KRAS and TP53 mutations. Patient is doing well at 6 months follow-up without any recurrence. Results (if a Case Study enter NA) NA Conclusion This case is an extremely rare case of primary peritoneal mucinous cystadenocarcinoma and thus requires consideration that it should be included in the differential diagnosis of peritoneal tumors.

Diagnostic Utility of Modified Method of AgNOR Staining in the Evaluation of Benign and Malignant Effusions

An exact identification of malignant cells in fluid by cytological examination is a well-known diagnostic challenge. One of the common problems is to distinguish reactive mesothelial cells from malignant cells. Conventional smears reported as ‘suspicious for malignancy’ indicate that the suspicious cases could not be classified with certainty as to whether they were reactive mesothelial cells or malignant cells. It poses problem in clinical staging of tumor, treatment and prognosis of malignancy. The purpose of the study was to determine the role of modified method of AgNOR staining in the evaluation of benign and malignant effusions. This cross-sectional study was conducted in the Department of Pathology, BIRDEM General Hospital, Dhaka, from July 2019 - June 2021. A total of 115 cases of effusion were included. All the samples were centrifuged and then smears were prepared from the deposit followed by staining with Hematoxylin & Eosin stain, Papanicolaou stain and AgNOR stain. At first the diagnosis was made on conventional smear method. Then the findings were compared and analyzed by modified AgNOR staining method. In malignant cells, the mean AgNOR count was 5.59±1.05 (±SD) and the AgNORs were multiple and irregular in shape. On the other hand, in benign cells the AgNORs were comparatively larger, single dots with a mean count of 1.31±0.48.The AgNOR count method has definite role in differentiating benign from malignant effusion. This method has supportive value which can be utilized in differentiating malignant effusions from the benign ones, especially in suspicious cases.

Gender- and Age-Based Characterization and Comparison of the Murine Primary Peritoneal Mesothelial Cell Proteome.

Organs in the abdominal cavity are covered by a peritoneal membrane, which is comprised of a monolayer of mesothelial cells (MC). Diseases involving the peritoneal membrane include peritonitis, primary cancer (mesothelioma), and metastatic cancers (ovarian, pancreatic, colorectal). These diseases have gender- and/or age-related pathologies; however, the impact of gender and age on the peritoneal MC is not well evaluated. To address this, we identified and characterized gender- and age-related differences in the proteomes of murine primary peritoneal MC. Primary peritoneal MC were isolated from young female (FY) or male (MY) mice (3-6 months) and aged female (FA) or male (MA) mice (20-23 months), lysed, trypsin digested using S-Traps, then subjected to bottom-up proteomics using an LC-Orbitrap mass spectrometer. In each cohort, we identified >1000 protein groups. Proteins were categorized using Gene Ontology and pairwise comparisons between gender and age cohorts were conducted. This study establishes baseline information for studies on peritoneal MC in health and disease at two physiologic age/gender points. Segregation of the data by gender and age could reveal novel factors to specific disease states involving the peritoneum. [This in vitro primary cell model has utility for future studies on the interaction between the mesothelium and foreign materials.].

Selective activation of PPARα by pemafibrate mitigates peritoneal inflammation and fibrosis through suppression of NLRP3 inflammasome and modulation of inflammation

Peritoneal inflammation and fibrosis remain major challenges to the long-term maintenance of peritoneal dialysis. Pemafibrate, a selective peroxisome proliferator-activated receptor α (PPARα) modulator, has been implicated in the management of fibrosis-related disorders. We investigated whether pemafibrate ameliorates peritoneal inflammation and fibrosis and explored the underlying mechanisms in mice with methylglyoxal (MGO)-induced peritoneal fibrosis (MGO mice). MGO mice exhibited peritoneal fibrosis with increased expression of mesenchymal markers, transforming growth factor-β1 (TGF-β1), and substantial deposition of extracellular matrix (ECM) proteins. Additionally, MGO mice exhibited peritoneal inflammation as indicated by elevated tumor necrosis factor-α expression and macrophage infiltration in peritoneal tissue. These effects were mitigated by pemafibrate treatment, which also restored peritoneal membrane function. Furthermore, pemafibrate promoted anti-inflammatory macrophage polarization in both mice and THP-1 cells. In human peritoneal mesothelial cells (HPMCs), pemafibrate effectively inhibited interferon-γ-induced production of TGF-β1 and ECM while suppressing the proinflammatory cytokines nuclear factor-κB (NF-κB) and activator protein 1. The NF-κB inhibitory effect of pemafibrate involved stabilization of the NF-κB inhibitory protein IkBα. Notably, pemafibrate hindered activation of the NLR family pyrin domain containing 3/caspase-1 axis in interferon-γ-stimulated THP-1 cells. These findings suggest that pemafibrate ameliorates peritoneal inflammation and fibrosis, making it a promising candidate for peritoneal fibrosis therapy.

Intraperitoneal administration of adeno-associated virus encoding microRNA-29b for the treatment of peritoneal metastasis.

This study explores a novel therapeutic approach for peritoneal metastasis (PM) using AAV-mediated delivery of tumor suppressor microRNA-29b (miR-29b) to peritoneal mesothelial cells (PMC). AAV serotypes 2 and DJ demonstrate high transduction efficiency for human and murine PMC, respectively. In vitro analysis indicates that AAV vectors encoding miR-29b precursor successfully elevate miR-29b expression in PMC and their secreted small extracellular vesicle (sEV), thereby inhibiting mesothelial mesenchymal transition and reducing subsequent attachment of tumor cells. A single intraperitoneal (IP) administration of AAV-DJ-miR-29b demonstrates robust and sustained transgene expression, suppressing peritoneal fibrosis and inhibiting the development of PM from gastric and pancreatic cancers. Additionally, AAV-DJ-miR-29b enhances the efficacy of IP chemotherapy using paclitaxel, restraining the growth of established PM. While conventional gene therapy for cancer encounters challenges targeting tumor cells directly but delivering miRNA to the tumor stroma offers a straightforward and efficient means of altering the microenvironment, leading to substantial inhibition of tumor growth. AAV-mediated miR-29b delivery to peritoneum via IP route presents a simple, minimally invasive, and promising therapeutic strategy for refractory PM.

Predictors of encapsulated peritoneal sclerosis in patients undergoing peritoneal dialysis using neutral-pH dialysate.

Encapsulated peritoneal sclerosis (EPS) is a serious complication in patients undergoing peritoneal dialysis (PD). Neutral-pH dialysate is associated with less peritoneal damage and a lower incidence of EPS than conventional PD solution. However, monitoring for peritoneal damage and predicting EPS remain important during PD therapy. We measured the mesothelial cell area, dialysate-to-plasma ratio of creatinine after 4h, and concentrations of the potential biological markers effluent fibrin degradation products (eFDPs), cancer antigen-125, and interleukin-6 in the effluent dialysate from patients who had been undergoing PD therapy for > 5years in our hospital. These biomarkers were obtained from the drainage fluid of the final measurement of peritoneal equilibration testing before withdrawal from PD therapy. The concentrations of these potential biomarkers were measured in 39 patients who withdrew from PD therapy and were enrolled in the study. Three participants developed EPS after withdrawing PD. The dialysate-to-plasma ratio of creatinine, area of mesothelial cells, and interleukin-6 appearance rate in participants who developed EPS tended to be higher than those in patients who did not, but there were no significant differences. Significantly more eFDPs were in participants who developed EPS than in those who did not (138.5 ± 15.1 vs. 32.9 ± 7.4µg/mL, P = 0.002). There was no difference in the cancer antigen-125 appearance rate between the groups. A cut-off value of eFDPs ≥ 119.1µg/mL was optimal for predicting EPS (P = 0.006, specificity = 0.972, sensitivity = 1.000). This study shows that eFDPs may be a useful biological marker for predicting EPS in patients undergoing PD using neutral-pH dialysate.

Sugar-binding Profiles of the Mesothelial Glycocalyx in Frozen Tissues of Mice Revealed by Lectin Staining

The mesothelium is a non-adhesive protective surface that lines the serosal cavities and organs within the body. The glycocalyx is a complex structure that coats the outer layer of the mesothelium. However, due to the limitations of conventional fixation techniques, studies on glycans are limited. In this study, lectin staining of frozen tissues was performed to investigate the diversity of glycans in the glycocalyx of mesothelial cells in mice. Datura stramonium lectin (DSL), which recognizes lactosamine and binds to Galectin-3 and -1, was broadly bound to the mesothelial cells of the visceral and parietal peritoneum but not to the pancreas, liver, intestine, or heart. Furthermore, human mesothelial cells in the omentum and parietal peritoneum were positive for DSL. Erythrina cristagalli lectin binding was specific to mesothelial cells in the parietal peritoneum, that is, the pleura, diaphragm, and peritoneum. Intriguingly, surface sialylation, the key element in reducing peritoneal dissemination and implantation, and promoting ascites formation by ovarian carcinoma cells, was much higher in the parietal peritoneum than in the omentum. These findings revealed slight differences in the glycans of mesothelial cells of different organs, which may be related to clinical diseases. These results also suggest that there may be differences in the functions of parietal and visceral mesothelial cells.

Gene therapy for diffuse pleural mesotheliomas in preclinical models by concurrent expression of NF2 and SuperHippo

Diffuse pleural mesothelioma (DPM) is a lethal cancer with a poor prognosis and limited treatment options. The Hippo signaling pathway genes, such as NF2 and LATS1/2, are frequently mutated in DPM, indicating a tumor suppressor role in the development of DPM. Here, we show that in DPM cell lines lacking NF2 and in mice with a conditional Nf2 knockout, downregulation of WWC proteins, another family of Hippo pathway regulators, accelerates DPM progression. Conversely, the expression of SuperHippo, a WWC-derived minigene, effectively enhances Hippo signaling and suppresses DPM development. Moreover, the adeno-associated virus serotype 6 (AAV6) has been engineered to deliver both NF2 and SuperHippo genes into mesothelial cells, which substantially impedes tumor growth in xenograft and genetic DPM models and prolongs the median survival of mice. These findings serve as a proof of concept for the potential use of gene therapy targeting the Hippo pathway to treat DPM.

The Role of Omentin-1 and Fibroblast Growth Factor-23 in Iraqi Patients with Prostate Cancer during Chemotherapy

Background: Omentin-1 is mainly expressed in stromal vascular cells of adipose tissue and can also be expressed in airway goblet cells, mesothelial cells, and vascular cells. Fibroblast growth factor 23 (FGF-23), generated by bone cells, regulates phosphate and vitamin D metabolism by regulating phosphate reabsorption in the kidneys and inhibiting vitamin D activation. Vitamin D is a fat-soluble vitamin that regulates calcium absorption, bone health, and immunological function. Prostate cancer is a significant health concern for men worldwide. Several studies demonstrated a link between these variables and cancer as they exert important anti-inflammatory, antioxidative, and anti-cancer functions. Objectives: To assess the impact of Omentin and FGF-23 biochemical functions, as well as the anti-cancer properties of vitamin D. Subjects and methods: This is a case-control study on serum samples collected from Iraqi prostate cancer patients after receiving chemotherapy at Al Amal Center in Imam Hussein Medical City in Karbala between November 2022 to May 2023. The serum samples were collected from two groups: control group consisted of 30 healthy males. Patient group consisted of 30 prostate cancer patients after receiving chemotherapy, both groups aged 45 – 80 years. The two groups were matched for body mass index. ELISA technology was used to estimate serum levels of the aforementioned biochemical parameters with vitamin D. Results: patient group had a significantly higher FGF-23 level than control group (309.5±41.65) versus (163.1±22.4) (p<0.001). On the other hand, Irisin, Omentin and Vitamin D mean serum concentrations were significantly lower in-patient group (15.2±4.24), (13.8±4.28) and (4.4±0.69) (p<0.001), respectively, compared to control group (60.8±3.5), (38.8±6.59), and (18.9±2.36), respectively. (ROC) curve analysis identified the best AUC values of FGF-23, Omentin, and Vitamin D (0.995, 0.959, 0.937), respectively, which suggests a high level of accuracy. Conclusions: These parameters may serve as critical indicators for prostate cancer patients and their disease progress. Vitamin D insufficiency is a risk factor for these individuals.

MORPHOLOGICAL SUBSTANTIATION OF THE EFFECTIVENESS OF PHOTODYNAMIC THERAPY IN CASE OF WIDESPREAD PERITONITIS IN AN EXPERIMENT

The article presents the results of experimental studies on the effects on the parietal and visceral peritoneum of intact animals and with simulated widespread peritonitis in white mongrel rats weighing 140 180 g. It was found that methylene blue at a concentration of 0.05% in intact animals at exposure of 5 minutes causes desquamation and small foci of necrosis of mesothelial cells, and in peritonitis against the background of photodynamic therapy has a beneficial effect on reparative processes due to the formation of singlet oxygen. The histological picture of the peritoneum in rats after abdominal sanitation by PDT at all stages of the study was qualitatively better than that of the representatives of the group during abdominal sanitation with 0.02% chlorhexidine solution. Based on the results of morphological studies, the authors recommend that the developed method of photodynamic sanitation of the abdominal cavity be introduced into clinical practice.

Cell-cell contact-dependent secretion of large-extracellular vesicles from EFNBhigh cancer cells accelerates peritoneal dissemination.

Large non-apoptotic vesicles released from the plasma membrane protrusions are classified as large-EVs (LEVs). However, the triggers of LEV secretion and their functions in tumors remain unknown. Coculture system of cancer cells, peritoneal mesothelial cells (PMCs), and macrophages (MΦs) was conducted to observe cell-cell contact-mediated LEV secretion. Lineage tracing of PMCs was performed using Wt1CreERT2-tdTnu mice to explore the effects of LEVs on PMCs in vivo, and lymphangiogenesis was assessed by qRT-PCR and flow-cytometry. In peritoneal dissemination, cancer cells expressing Ephrin-B (EFNB) secreted LEVs upon the contact with PMCs expressing ephrin type-B (EphB) receptors, which degraded mesothelial barrier by augmenting mesothelial-mesenchymal transition. LEVs were incorporated in subpleural MΦs, and these MΦs transdifferentiated into lymphatic endothelial cells (LEC) and integrated into the lymphatic vessels. LEC differentiation was also induced in PMCs by interacting with LEV-treated MΦs, which promoted lymphangiogenesis. Mechanistically, activation of RhoA-ROCK pathway through EFNB reverse signaling induced LEV secretion. EFNBs on LEVs activated EphB forward signaling in PMC and MΦs, activating Akt, ERK and TGF-β1 pathway, which were indispensable for causing MMT and LEC differentiation. LEVs accelerated peritoneal dissemination and lymphatic invasions by cancer cells. Blocking of EFNBs on LEVs using EphB-Fc-fusion protein attenuated these events. EFNBhigh cancer cells scattered LEVs when they attached to PMCs, which augmented the local reactions of PMC and MΦ (MMT and lymphangiogenesis) and exaggerated peritoneal dissemination.

Microgravity as a Tool to Investigate Cancer Induction in Pleura Mesothelial Cells.

The present work shows that the exposure of mesothelial cells to simulated microgravity changes their cytoskeleton and adhesion proteins, leading to a cell switch from normal towards tumoral cells. Immunohistochemical and molecular data were obtained from both MeT-5A exposed to simulated microgravity and BR95 mesothelioma cell lines. Simulated microgravity was found to affect the expression of actin, vinculin, and connexin-43, altering their quantitative and spatial distribution pattern inside the cell. The analysis of the tumoral markers p27, CD44, Fibulin-3, and NANOG and the expression of genes related to cancer transformation such as NANOG, CDH-1, and Zeb-1 showed that the simulated microgravity environment led to expression patterns in MeT-5A cells similar to those observed in BR95 cells. The alteration in both quantitative expression and structural organization of the cytoskeleton and adhesion/communication proteins can thus be considered a pivotal mechanism involved in the cellular shift towards tumoral progression.

Flow cytometry of non-hematopoietic cells in canine effusions.

The identification of non-hematopoietic cells in effusions is a diagnostic challenge in cytology. Biopsies from mesothelium or primary lesions are infrequently performed in clinical settings and immunochemistry on smears or immunohistochemistry on cell blocks are the most common ancillary test to refine the cytological diagnosis. Cavitary effusions are an ideal matrix for flow cytometry and the availability of a cytometric panel to describe non-hematopoietic cells would represent a useful tool. Here we present the results of the flow cytometric and immunohistochemical determination of cytokeratin (CK), vimentin (VIM) and desmin (DES) in 36 canine effusions. The concordance between the two methods was perfect for CK (100%), substantial for VIM (77.8%), and almost perfect for DES (97.2%). The panel was interpreted to define the epithelial (CK+VIM-DES-), mesothelial (CK+VIM+DES+), or mesenchymal (CK-VIM+DES-) origin of the cells. Unexpected profiles were considered doubtful and observed patterns were individually discussed. The concordance of the panel interpretation between two methods was 75%. The evaluation of discordant and doubtful cases suggests a lower sensitivity of flow cytometry in detecting VIM expression and revealed a high frequency of VIM+ epithelial cells, variable expression of VIM in mesothelial cells, and an important role of DES in excluding an epithelial origin when positive. Multicentric studies based on histopathological diagnoses are necessary to confirm these findings and evaluate the diagnostic utility of the panel to refine cytological diagnosis. Our results show that flow cytometry can be a timesaving alternative to IHC on cell blocks in clinical settings to detect CK, VIM and DES expression. The interpretation of the panel is similar in most cases; however, occasional discordant results, particularly for VIM, may occur.