Caffeic acid phenethyl ester restores mitochondrial homeostasis against peritoneal fibrosis induced by peritoneal dialysis through the AMPK/SIRT1 pathway.

Increasing evidence suggests that peritoneal fibrosis induced by peritoneal dialysis (PD) is linked to oxidative stress. However, there are currently no effective interventions for peritoneal fibrosis. In the present study, we explored whether adding caffeic acid phenethyl ester (CAPE) to peritoneal dialysis fluid (PDF) improved peritoneal fibrosis caused by PD and explored the molecular mechanism. We established a peritoneal fibrosis model in Sprague-Dawley rats through intraperitoneal injection of PDF and lipopolysaccharide (LPS). Rats in the PD group showed increased peritoneal thickness, submesothelial collagen deposition, and the expression of TGFß1 and α-SMA. Adding CAPE to PDF significantly inhibited PD-induced submesothelial thickening, reduced TGFß1 and α-SMA expression, alleviated peritoneal fibrosis, and improved the peritoneal ultrafiltration function. In vitro, peritoneal mesothelial cells (PMCs) treated with PDF showed inhibition of the AMPK/SIRT1 pathway, mitochondrial membrane potential depolarization, overproduction of mitochondrial reactive oxygen species (ROS), decreased ATP synthesis, and induction of mesothelial-mesenchymal transition (MMT). CAPE activated the AMPK/SIRT1 pathway, thereby inhibiting mitochondrial membrane potential depolarization, reducing mitochondrial ROS generation, and maintaining ATP synthesis. However, the beneficial effects of CAPE were counteracted by an AMPK inhibitor and siSIRT1. Our results suggest that CAPE maintains mitochondrial homeostasis by upregulating the AMPK/SIRT1 pathway, which alleviates oxidative stress and MMT, thereby mitigating the damage to the peritoneal structure and function caused by PD. These findings suggest that adding CAPE to PDF may prevent and treat peritoneal fibrosis.

Comparison of the effect of Everolimus, Prednisolone, and a combination of both on experimentally induced peritoneal adhesions in rats.

Postoperative intra-abdominal adhesions represent a significant post-surgical problem. Its complications can cause a considerable clinical and cost burden. Herein, our study aimed to investigate the effect of Everolimus on peritoneal adhesion formation after inducing adhesions in rats. In this experimental study, adhesion bands were induced by intraperitoneal injection of 3 ml of 10% sterile talc solution in 64 male albino rats. The first group served as the control group. The second one received oral Prednisolone (1 mg/kg/day), the third received Everolimus (0.1 mg/kg/day), and group four received both drugs with similar dosages for four consecutive weeks. The formation of adhesion bands was qualitatively graded according to the Nair classification. The rats in the control group had extensive adhesions between the abdominal wall and the organs. Regarding substantial adhesion formation, 50% (8/16) of animals in the control group had substantial adhesions, while this rate in the groups receiving Prednisolone, Everolimus, and combination treatment was 31%, 31%, and 31%, respectively. Also, 68.75% (5/11) of the Prednisolone recipients had insubstantial adhesions, the same as Everolimus recipients, while in the combination group, 66.66% (10/15) rats had insubstantial adhesions. Everolimus demonstrated satisfactory results in reducing the rates of induced peritoneal adhesion in an experimental model, similar to Prednisolone and superior to a combination regime.

MiR-29b may suppresses peritoneal metastases through inhibition of the mesothelial-mesenchymal transition (MMT) of human peritoneal mesothelial cells.

Peritoneal dissemination is a major metastatic pathway for gastrointestinal and ovarian malignancies. The miR-29b family is downregulated in peritoneal fluids in patients with peritoneal metastases (PM). We examined the effect of miR-29b on mesothelial cells (MC) which play critical a role in the development of PM through mesothelial-mesenchymal transition (MMT). Human peritoneal mesothelial cells (HPMCs) were isolated from surgically resected omental tissue and MMT induced by stimulation with 10 ng/ml TGF-ß1. MiR-29b mimics and negative control miR were transfected by lipofection using RNAiMAX and the effects on the MMT evaluated in vitro. HPMC produced substantial amounts of miR-29b which was markedly inhibited by TGF-ß1. TGF-ß1 stimulation of HPMC induced morphological changes with decreased expression of E-cadherin and calretinin, and increased expression of vimentin and fibronectin. TGF-ß1 also enhanced proliferation and migration of HPMC as well as adhesion of tumor cells in a fibronectin dependent manner. However, all events were strongly abrogated by simultaneous transfection of miR-29b. MiR-29b inhibits TGF-ß1 induced MMT and replacement of miR-29b in the peritoneal cavity might be effective to prevent development of PM partly through the effects on MC.

Cytoreductive Surgery and Hyperthermic Intraperitoneal Chemotherapy for Colorectal Peritoneal Metastases: A Systematic Review.

BACKGROUND: Combined treatment modality of cytoreductive surgery and hyperthermic intraperitoneal chemotherapy is emerging as an alternative option for colorectal peritoneal metastases, but there is ambiguity regarding patient selection, treatment protocols, and efficacy. OBJECTIVE: To elaborate on the patient characteristics, hyperthermic intraperitoneal chemotherapy protocol and health outcomes in colorectal peritoneal metastases patients undergoing a combination of hyperthermic intraperitoneal chemotherapy and cytoreductive surgery and provide guidance for future studies. DATA SOURCES: A Medline search for English language studies published between 2004 and 2019. STUDY SELECTION: Medical subject headings and key terms, including: hyperthermic intraperitoneal chemotherapy, colorectal peritoneal metastases, colorectal cancer and combinations thereof as per guidelines. MAIN OUTCOME MEASURES: Overall survival, disease-free survival, and morbidity and mortality rates. RESULTS: Of the 26 included studies, 42% were published between 2016 and 2019. More than half of the studies were retrospective in nature and conducted in tertiary specialized centers outside of the United States. The median age range was 44 to 62 years. Mitomycin C-based therapy was seen in 50% of studies. Mean weighted median disease-free survival for 11 studies was 15 months (9 to 36 months). Median OS ranged from 12 to 63 months, with an average of 33.6 months among 20 studies. Overall morbidity varied from 11% to 56%, with a weighted mean of 29% in 18 studies. Mortality ranged from 0 to 34%, with a weighted mean of 4% in 15 studies. LIMITATIONS: Despite careful study selection, variability in methodology of the included studies can limit review findings. CONCLUSION: Due to study heterogeneity, and a recent large, randomized trial showing no overall benefit, use of cytoreductive surgery with hyperthermic intraperitoneal chemotherapy in colorectal peritoneal metastases patients is highly controversial. Further standardized controlled studies can help uniformly define and build consensus among the medical community on patient eligibility and the optimal hyperthermic intraperitoneal chemotherapy techniques. PROSPERO: Registered on March 3, 2020, CRD42020146942.

Mitoquinone treatment for the prevention of surgical adhesions via regulation of the NRF2/HO-1 signaling pathway in mice.

BACKGROUND: Postoperative adhesion is a common cause of long-term morbidity after abdominal or pelvic surgery. The development of postoperative adhesion involves oxidative stress, inflammatory response, and collagen deposition mechanisms. Here, we demonstrate that mitoquinone could be useful for the treatment of postoperative adhesion. METHODS: A murine adhesion model was established by induction of peritoneal ischemic buttons. Mice received different doses of mitoquinone via the tail vein. All the ischemic buttons were dissected at 1 day and 7 days after surgery to investigate the effect of mitoquinone in the early and late stage of the adhesion process, respectively. Human peritoneal mesothelial cells were treated with H2O2 to examine the potential mechanisms of mitoquinone in oxidative insult. RESULTS: Postoperative adhesion scores were markedly decreased in mitoquinone-treated mice compared with the control mice. The degree of oxidative stress, inflammatory injury, and collagen deposition were also significantly reduced in the mitoquinone-treated mice. The expression of plasminogen-activating inhibitor, interleukin-1, interleukin-6, tumor necrosis factor-α, vascular endothelial growth factor, malondialdehyde, and nitric oxide was decreased, while the expression of tissue-type plasminogen activator, glutathione, superoxide dismutase, and Nrf2 was increased in the peritoneal ischemic buttons after mitoquinone treatment. Cellular reactive oxygen species and the canonical inflammatory pathway were inhibited in mitoquinone-treated human peritoneal mesothelial cells after H2O2 challenge. Mechanistically, mitoquinone was found to enhance the activity of Nrf2 and heme oxygenase-1 and to induce nuclear translocation of Nrf2 in human peritoneal mesothelial cells. CONCLUSION: The mitochondria-targeting antioxidant molecule mitoquinone attenuates postoperative adhesion formation by inhibiting oxidative stress, inflammation, and collagen accumulation, and therefore provides a therapeutic agent for the management of surgical adhesion.

Intraperitoneal Lavage with Crocus sativus Prevents Postoperative-Induced Peritoneal Adhesion in a Rat Model: Evidence from Animal and Cellular Studies.

Postoperative peritoneal adhesions are considered the major complication following abdominal surgeries. The primary clinical complications of peritoneal adhesion are intestinal obstruction, infertility, pelvic pain, and postoperative mortality. In this study, regarding the anti-inflammatory and antioxidant activities of Crocus sativus, we aimed to evaluate the effects of Crocus sativus on the prevention of postsurgical-induced peritoneal adhesion. Male Wistar-Albino rats were used to investigate the preventive effects of C. sativus extract (0.5%, 0.25% and 0.125% w/v) against postsurgical-induced peritoneal adhesion compared to pirfenidone (PFD, 7.5% w/v). We also investigated the protective effects of PFD (100 µg/ml) and C. sativus extract (100, 200, and 400 µg/ml) in TGF-ß1-induced fibrotic macrophage polarization. The levels of cell proliferation and oxidative, antioxidative, inflammatory and anti-inflammatory, fibrosis, and angiogenesis biomarkers were evaluated both in vivo and in vitro models. C. sativus extract ameliorates postoperational-induced peritoneal adhesion development by attenuating oxidative stress [malondialdehyde (MDA)]; inflammatory mediators [interleukin- (IL-) 6, tumour necrosis factor- (TNF-) α, and prostaglandin E2 (PGE2)]; fibrosis [transforming growth factor- (TGF-) ß1, IL-4, and plasminogen activator inhibitor (PAI)]; and angiogenesis [vascular endothelial growth factor (VEGF)] markers, while propagating antioxidant [glutathione (GSH)], anti-inflammatory (IL-10), and fibrinolytic [tissue plasminogen activator (tPA)] markers and tPA/PAI ratio. In a cellular model, we revealed that the extract, without any toxicity, regulated the levels of cell proliferation and inflammatory (TNF-α), angiogenesis (VEGF), anti-inflammatory (IL-10), M1 [inducible nitric oxide synthase (iNOS)] and M2 [arginase-1 (Arg 1)] biomarkers, and iNOS/Arg-1 ratio towards antifibrotic M1 phenotype of macrophage, in a concentration-dependent manner. Taken together, the current study indicated that C. sativus reduces peritoneal adhesion formation by modulating the macrophage polarization from M2 towards M1 cells.

Comparison of Isotonic Activation of Cell Volume Regulation in Rat Peritoneal Mesothelial Cells and in Kidney Outer Medullary Collecting Duct Principal Cells.

In disease states, mesothelial cells are exposed to variable osmotic conditions, with high osmotic stress exerted by peritoneal dialysis (PD) fluids. They contain unphysiologically high concentrations of glucose and result in major peritoneal membrane transformation and PD function loss. The effects of isotonic entry of urea and myo-inositol in hypertonic (380 mOsm/kg) medium on the cell volume of primary cultures of rat peritoneal mesothelial cells and rat kidney outer medullary collecting duct (OMCD) principal cells were studied. In hypertonic medium, rat peritoneal mesothelial cells activated a different mechanism of cell volume regulation in the presence of isotonic urea (100 mM) in comparison to rat kidney OMCD principal cells. In kidney OMCD cells inflow of urea into the shrunken cell results in restoration of cell volume. In the shrunken peritoneal mesothelial cells, isotonic urea inflow caused a small volume increase and activated regulatory volume decrease (RVD). Isotonic myo-inositol activated RVD in hypertonic medium in both cell types. Isotonic application of both osmolytes caused a sharp increase of intracellular calcium both in peritoneal mesothelial cells and in kidney OMCD principal cells. In conclusion, peritoneal mesothelial cells exhibit RVD mechanisms when challenged with myo-inositol and urea under hyperosmolar isotonic switch from mannitol through involvement of calcium-dependent control. Myo-inositol effects were identical with the ones in OMCD principal cells whereas urea effects in OMCD principal cells led to no RVD induction.

The Study of Efficiency of the Approach to Prevent the Adhesions in the Abdominal Cavity of Rats.

Adhesions in rat abdominal cavity were studied after laparotomy and subsequent single intraperitoneal injection of 2 ml of 5% aqueous solution of oxidized dextran (OD) with a molecular weight of 40 kDa (oxidation degree 10%). On days 7 and 21 after laparotomy, the number of adhesions in OD-treated rats was lower by 7.5 and 4 times than in animals not receiving OD. The number of neutrophils in adhesions on day 21 was manyfold lower in OD-treated rats. In 7 and 21 days after laparotomy, the number of fibroblasts in the adhesions of rats receiving and not receiving OD was similar, but 2-fold higher than in the peritoneum of non-operated rats. The content of collagen in adhesions on day 21 after laparotomy in OD-treated rats was 10-fold lower than in animals no receiving OD.

A fully implantable device for intraperitoneal drug delivery refilled by ingestible capsules.

Creating fully implantable robots that replace or restore physiological processes is a great challenge in medical robotics. Restoring blood glucose homeostasis in patients with type 1 diabetes is particularly interesting in this sense. Intraperitoneal insulin delivery could revolutionize type 1 diabetes treatment. At present, the intraperitoneal route is little used because it relies on accessing ports connecting intraperitoneal catheters to external reservoirs. Drug-loaded pills transported across the digestive system to refill an implantable reservoir in a minimally invasive fashion could open new possibilities in intraperitoneal delivery. Here, we describe PILLSID (PILl-refiLled implanted System for Intraperitoneal Delivery), a fully implantable robotic device refillable through ingestible magnetic pills carrying drugs. Once refilled, the device acts as a programmable microinfusion system for precise intraperitoneal delivery. The robotic device is grounded on a combination of magnetic switchable components, miniaturized mechatronic elements, a wireless powering system, and a control unit to implement the refilling and control the infusion processes. In this study, we describe the PILLSID prototyping. The device key blocks are validated as single components and within the integrated device at the preclinical level. We demonstrate that the refilling mechanism works efficiently in vivo and that the blood glucose level can be safely regulated in diabetic swine. The device weights 165 grams and is 78 millimeters by 63 millimeters by 35 millimeters, comparable with commercial implantable devices yet overcoming the urgent critical issues related to reservoir refilling and powering.

Development of rotational intraperitoneal pressurized aerosol chemotherapy to enhance drug delivery into the peritoneum.

This study aims to evaluate the drug distribution, tissue concentrations, penetration depth, pharmacokinetic properties, and toxicities after rotational intraperitoneal pressurized aerosol chemotherapy (RIPAC) in pigs. Because relevant medical devices have not been introduced, we developed our prototype of pressurized intraperitoneal aerosol chemotherapy (PIPAC) and RIPAC by adding a conical pendulum motion device for rotating the nozzle. RIPAC and PIPAC were conducted using 150 ml of 1% methylene blue to evaluate the drug distribution and 3.5 mg of doxorubicin in 50 ml of 0.9% NaCl to evaluate the tissue concentrations and penetration depth, pharmacokinetic properties, and toxicities. All agents were sprayed as aerosols via the nozzle, DreamPen® (Dalim Biotech, Gangwon, South Korea), with a velocity of 5 km/h at a flow rate of 30 ml/min under a pressure of 7 bars, and capnoperitoneum of 12 mmHg was maintained for 30 min. As a result, RIPAC showed a wider distribution and stronger intensity than PIPAC. Compared with PIPAC, RIPAC demonstrated high values of the tissue concentration in the central, right upper, epigastrium, left upper, left lower, right lower, and right flank regions (median, 375.5-2124.9 vs. 161.7-1240 ng/ml; p ≤ .05), and higher values of the depth of concentrated diffusion and depth of maximal diffusion (median, 232.5-392.7 vs. 116.9-240.1 µm; 291.2-551.2 vs. 250.5-362.4 µm; p ≤ .05) in all regions except for bowels. In RIPAC, the pharmacokinetic properties reflected hemodynamic changes during capnoperitoneum, and there were no related toxicities. Conclusively, RIPAC may have the potential to enhance drug delivery into the peritoneum compared to PIPAC.

Effects of TGF-ß1 Receptor Inhibitor GW788388 on the Epithelial to Mesenchymal Transition of Peritoneal Mesothelial Cells.

We investigated the effectiveness of the transforming growth factor beta-1 (TGF-ß) receptor inhibitor GW788388 on the epithelial to mesenchymal transition (EMT) using human peritoneal mesothelial cells (HPMCs) and examined the effectiveness of GW788388 on the peritoneal membrane using a peritoneal fibrosis mouse model. HPMCs were treated with TGF-ß with or without GW788388. Animal experiments were conducted on male C57/BL6 mice. Peritoneal fibrosis was induced by intraperitoneal injection of chlorhexidine gluconate. GW788388 was administered by once-daily oral gavage. The morphological change, cell migration, and invasion resulted from TGF-ß treatment, but these changes were attenuated by cotreatment with GW788388. TGF-ß-treated HPMCs decreased the level of the epithelial cell marker and increased the levels of the mesenchymal cell markers. Cotreatment with GW788388 reversed these changes. Phosphorylated Smad2 and Smad3 protein levels were stimulated with TGF-ß and the change was attenuated by cotreatment with GW788388. For the peritoneal fibrosis mice, thickness and collagen deposition of parietal peritoneum was increased, but this change was attenuated by cotreatment with GW788388. GW788388, an orally available potent TGF-ß receptor type 1 inhibitor, effectively attenuated TGF-ß-induced EMT in HPMCs. Cotreatment with GW788388 improved peritoneal thickness and fibrosis, and recovered peritoneal membrane function in a peritoneal fibrosis mouse model.

Blocking core fucosylation of epidermal growth factor (EGF) receptor prevents peritoneal fibrosis progression.

OBJECTIVE: Peritoneal fibrosis (PF) ultimately causes ultrafiltration failure and peritoneal dialysis (PD) termination, but there are few effective therapies for it. Core fucosylation, which is catalyzed by α1,6-fucosyltransferase (Fut8) in mammals, may play a crucial role in PF development. This study aims to assess the effects of inhibiting core fucosylation of epidermal growth factor (EGF) receptor on PF rats. METHODS: PF rats (established by 4.25% glucose dialysate) were treated with either an adenovirus-Fut8 short hairpin RNA (Fut8shRNA) or adenovirus-control. Masson's staining and net ultrafiltration were performed at week six. Fut8 level and core fucosylation of EGF receptor and collagen I in the peritoneal membrane were assessed, and EGF signaling was detected, including signal transducer and activator of transcription 3 (STAT3), nuclear factor kappa B (NF-κB) and their phosphorylation. Monocyte chemoattractant protein-1 (MCP-1) in peritoneal effluent was examined. RESULTS: Fut8 was upregulated in PF rats but decreased after Fut8shRNA treatment. EGF and EGF receptor expression was upregulated in PF rats, while core fucosylation of EGF receptor decreased after Fut8shRNA treatment. Masson's staining results showed an increase in peritoneal thickness in PF rats but a decrease after Fut8shRNA treatment. Fut8shRNA treatment increased net ultrafiltration, reduced the expression of collagen I and MCP-1 compared to PF rats. Fut8shRNA treatment suppressed phosphorylation of STAT3 and NF-κB in the peritoneal membrane of PF rats. CONCLUSIONS: Fut8shRNA treatment ameliorated the fibrotic changes in PF rats. A potential mechanism may be that Fut8shRNA treatment inactivated EGF signaling pathway by suppressing the phosphorylation of STAT3 and NF-κB.

C1 inhibitor mitigates peritoneal injury in zymosan-induced peritonitis.

Peritonitis, due to a fungal or bacterial infection, leads to injury of the peritoneal lining and thereby forms a hazard for the long-term success of peritoneal dialysis (PD) and remains a lethal complication in patients with PD. This study investigated whether C1 inhibitor (C1-INH) could protect against the progression of peritoneal injuries with five daily administrations of zymosan after mechanical scraping of the rat peritoneum to mimic fungal peritonitis. Severe peritoneal injuries were seen in this model, accompanied by fibrinogen/fibrin exudation and peritoneal deposition of complement activation products such as activated C3 and C5b-9. However, intraperitoneal injection of C1-INH decreased peritoneal depositions of activated C3 and C5b-9, ameliorated peritoneal thickening, reduced the influx of inflammatory cells, and prevented the production of peritoneal fibrous layers with both one and two doses of C1-INH each day. Our results suggest that C1-INH might be useful to protect against peritoneal injuries after causes of peritonitis such as fungal infection. This clinically available agent may thus help extend the duration of PD.NEW & NOTEWORTHY Peritoneal injuries associated with peritonitis comprise an important issue to prevent long-term peritoneal dialysis (PD) therapy. Here, we showed that C1 inhibitor (C1-INH), as an anticomplement agent, protected against peritoneal injuries in a peritonitis animal model related to fungal infection. Therefore, C1-INH might be useful to protect against peritoneal injuries after peritonitis due to fungal infection. This clinically available agent may thus help extend the duration of PD.

Hypochlorous acid selectively promotes toxicity and the expression of danger signals in human abdominal cancer cells.

Tumors of the abdominal cavity, such as colorectal, pancreatic and ovarian cancer, frequently metastasize into the peritoneum. Large numbers of metastatic nodules hinder curative surgical resection, necessitating lavage with hyperthermic intraperitoneal chemotherapy (HIPEC). However, HIPEC not only causes severe side effects but also has limited therapeutic efficacy in various instances. At the same time, the age of immunotherapies such as biological agents, checkpoint­ inhibitors or immune­cell therapies, increasingly emphasizes the critical role of anticancer immunity in targeting malignancies. The present study investigated the ability of three types of long­lived reactive species (oxidants) to inactivate cancer cells and potentially complement current HIPEC regimens, as well as to increase tumor cell expression of danger signals that stimulate innate immunity. The human abdominal cancer cell lines HT­29, Panc­01 and SK­OV­3 were exposed to different concentrations of hydrogen peroxide (H2O2), hypochlorous acid (HOCl) and peroxynitrite (ONOO­). Metabolic activity was measured, as well as determination of cell death and danger signal expression levels via flow cytometry and detection of intracellular oxidation via high­content microscopy. Oxidation of tumor decreased intracellular levels of the antioxidant glutathione and induced oxidation in mitochondria, accompanied by a decrease in metabolic activity and an increase in regulated cell death. At similar concentrations, HOCl showed the most potent effects. Non­malignant HaCaT keratinocytes were less affected, suggesting the approach to be selective to some extent. Pro­immunogenic danger molecules were investigated by assessing the expression levels of calreticulin (CRT), and heat­shock protein (HSP)70 and HSP90. CRT expression was greatest following HOCl and ONOO­ treatment, whereas HOCl and H2O2 resulted in the greatest increase in HSP70 and HSP90 expression levels. These results suggested that HOCl may be a promising agent to complement current HIPEC regimens targeting peritoneal carcinomatosis.

Protective Effects of Baicalin on Peritoneal Tight Junctions in Piglets Challenged with Glaesserella parasuis.

Glaesserella parasuis (G. parasuis) causes inflammation and damage to piglets. Whether polyserositis caused by G. parasuis is due to tight junctions damage and the protective effect of baicalin on it have not been examined. Therefore, this study aims to investigate the effects of baicalin on peritoneal tight junctions of piglets challenged with G. parasuis and its underlying molecular mechanisms. Piglets were challenged with G. parasuis and treated with or without baicalin. RT-PCR was performed to examine the expression of peritoneal tight junctions genes. Immunofluorescence was carried out to detect the distribution patterns of tight junctions proteins. Western blot assays were carried out to determine the involved signaling pathways. Our data showed that G. parasuis infection can down-regulate the tight junctions expression and disrupt the distribution of tight junctions proteins. Baicalin can alleviate the down-regulation of tight junctions mRNA in peritoneum, prevent the abnormalities and maintain the continuous organization of tight junctions. Our results provide novel evidence to support that baicalin has the capacity to protect peritoneal tight junctions from G. parasuis-induced inflammation. The protective mechanisms of baicalin could be associated with inhibition of the activation of PKC and MLCK/MLC signaling pathway. Taken together, these data demonstrated that baicalin is a promising natural agent for the prevention and treatment of G. parasuis infection.

Mesothelin blockage by Amatuximab suppresses cell invasiveness, enhances gemcitabine sensitivity and regulates cancer cell stemness in mesothelin-positive pancreatic cancer cells.

BACKGROUND: Mesothelin is a 40-kDa glycoprotein that is highly overexpressed in various types of cancers, however molecular mechanism of mesothelin has not been well-known. Amatuximab is a chimeric monoclonal IgG1/k antibody targeting mesothelin. We recently demonstrated that the combine therapy of Amatuximab and gemcitabine was effective for peritonitis of pancreatic cancer in mouse model. METHODS: We discover the role and potential mechanism of mesothelin blockage by Amatuximab in human pancreatic cells both expressing high or low level of mesothelin in vitro experiment and peritonitis mouse model of pancreatic cancer. RESULTS: Mesothelin blockage by Amatuximab lead to suppression of invasiveness and migration capacity in AsPC-1 and Capan-2 (high mesothelin expression) and reduce levels of pMET expression. The combination of Amatuximab and gemcitabine suppressed proliferation of AsPC-1 and Capan-2 more strongly than gemcitabine alone. These phenomena were not observed in Panc-1 and MIA Paca-2 (Mesothelin low expression). We previously demonstrated that Amatuximab reduced the peritoneal mass in mouse AsPC-1 peritonitis model and induced sherbet-like cancer cell aggregates, which were vanished by gemcitabine. In this study, we showed that the cancer stem cell related molecule such as ALDH1, CD44, c-MET, as well as proliferation related molecules, were suppressed in sherbet-like aggregates, but once sherbet-like aggregates attached to peritoneum, they expressed these molecules strongly without the morphological changes. CONCLUSIONS: Our work suggested that Amatuximab inhibits the adhesion of cancer cells to peritoneum and suppresses the stemness and viability of those, that lead to enhance the sensitivity for gemcitabine.

Peritoneal melanosis associated with metastatic melanoma previously treated with targeted and immune checkpoint inhibitor therapy.

Peritoneal melanosis is an uncommon benign condition, the pathophysiology of which is unclear. Macroscopically, it appears as diffuse dark brown or black pigmentation within the peritoneum, mimicking more sinister conditions such as metastatic melanoma. It has been described in a variety of contexts, but only exceedingly rarely in association with metastatic melanoma, with only two previous published case reports. We present a case of peritoneal melanosis associated with metastatic melanoma involving the spleen, previously treated with targeted and immune checkpoint inhibitor therapy. With increasing reports of melanoma regression manifesting as cutaneous tumorous melanosis in patients treated with immune checkpoint inhibitors, we postulate that, similarly, immunotherapy and tumour regression might have a role to play in the pathogenesis of the peritoneal pigmentation in this case.

Dipeptidyl peptidase 4 promotes peritoneal fibrosis and its inhibitions prevent failure of peritoneal dialysis.

Peritoneal dialysis (PD) possesses multiple advantages for end stage renal disease. However, long-term PD triggers peritoneal fibrosis (PF). From the nationwide analysis of diabetic PD patients (n = 19,828), we identified the incidence of PD failure was significantly lower in diabetic patients treated with dipeptidyl peptidase 4 (DPP4) inhibitors. Experimental study further showed high concentration of glucose remarkably enhanced DPP4 to promote epithelial-mesenchymal transition (EMT) in the mesothelial cells. In chlorhexidine gluconate (CG)-induced PF model of rats, DPP4 expression was enriched at thickening peritoneum. Moreover, as to CG-induced PF model, DPP4 deficiency (F344/DuCrlCrlj strain), sitagliptin and exendin-4 treatments significantly inhibited DPP4 to reverse the EMT process, angiogenesis, oxidative stress, and inflammation, resulting in the protection from PF, preservation of peritoneum and the corresponding functional integrity. Furthermore, DPP4 activity was significantly correlated with peritoneal dysfunction. Taken together, DPP4 caused peritoneal dysfunction/PF, whereas inhibition of DPP4 protected the PD patients against PD failure.

A Novel Formulation of Glucose-Sparing Peritoneal Dialysis Solutions with l-Carnitine Improves Biocompatibility on Human Mesothelial Cells.

The main reason why peritoneal dialysis (PD) still has limited use in the management of patients with end-stage renal disease (ESRD) lies in the fact that the currently used glucose-based PD solutions are not completely biocompatible and determine, over time, the degeneration of the peritoneal membrane (PM) and consequent loss of ultrafiltration (UF). Here we evaluated the biocompatibility of a novel formulation of dialytic solutions, in which a substantial amount of glucose is replaced by two osmometabolic agents, xylitol and l-carnitine. The effect of this novel formulation on cell viability, the integrity of the mesothelial barrier and secretion of pro-inflammatory cytokines was evaluated on human mesothelial cells grown on cell culture inserts and exposed to the PD solution only at the apical side, mimicking the condition of a PD dwell. The results were compared to those obtained after exposure to a panel of dialytic solutions commonly used in clinical practice. We report here compelling evidence that this novel formulation shows better performance in terms of higher cell viability, better preservation of the integrity of the mesothelial layer and reduced release of pro-inflammatory cytokines. This new formulation could represent a step forward towards obtaining PD solutions with high biocompatibility.