The histophysiology and pathophysiology of the peritoneum

The journey of nanoparticles in the abdominal cavity: Exploring their in vivo fate and impact factors

Peritoneal carcinomatosis (PC) is caused by metastasis of primary tumor cells from intra-abdominal organs to the peritoneal surface. Intraperitoneal (IP) chemotherapy allows close contact of high concentrations of therapeutic agents with cancer cells in the peritoneal cavity to prolong patient survival. However, conventional IP chemotherapy is prone to rapid elimination from the peritoneal cavity and lacks specificity towards cancer cells. To address these challenges, there is an imperative demand for exploiting novel drug delivery systems to enhance drug retention in the peritoneal cavity and target PC cells. Therefore, in this review, we first recapitulate the physiological structures and barriers associated with IP drug delivery, highlighting the in vivo fate of nanoparticles (NPs) after IP administration. Furthermore, the influence of physicochemical properties (particle size, charge, surface modification, and carrier composition) on the in vivo fate of NPs is discussed. Perspectives on the rational design of NPs for IP therapy and recent clinical progress are also provided.

Beyond tumor‑associated macrophages involved in spheroid formation and dissemination: Novel insights for ovarian cancer therapy (Review)

Ovarian cancer (OC) is the most common and deadly malignant tumor of the female reproductive system. When OC cells detach from the primary tumor and enter the ascitic microenvironment, they are present as individual cells or multicellular spheroids in ascites. These spheroids, composed of cancer and non‑malignant cells, are metastatic units and play a crucial role in the progression of OC. However, little is known about the mechanism of spheroid formation and dissemination. Tumor‑associated macrophages (TAMs) in the center of spheroids are key in spheroid formation and metastasis and provide a potential target for OC therapy. The present review summarizes the key biological features of spheroids, focusing on the role of TAMs in spheroid formation, survival and peritoneal metastasis, and the strategies targeting TAMs to provide new insights in treating OC.

Detailed analysis of the histology-specific impact of ascites volume on the outcome of epithelial ovarian cancer: a multi-institutional retrospective cohort study

BACKGROUND

The accumulation of ascites is a major symptom of ovarian cancer. The volume of ascites is a pathophysiological indicator of the peritoneal environment, such as inflammation and fibrosis; however, the relationship between the volume of ascites and oncological outcomes remains unclear. We herein retrospectively examined the effects of the volume of ascites on the prognosis of epithelial ovarian cancer in a multi-institutional large cohort using the stratification of clinical characteristics and statistical adjustment methods.

METHODS

Of 5,268 patients with ovarian tumors in the Tokai Ovarian Tumor Study Group between 1986 and 2020, we included 1,966 cases of epithelial ovarian cancer and examined the relationship between the volume of ascites at the initial surgery and the prognosis of patients. We performed a multivariate analysis and propensity score weighting for covariate adjustments to precisely estimate the prognostic impact of ascites accumulation. A subgroup analysis was also performed to examine differences in the prognostic implications of ascites accumulation among histotypes.

RESULTS

A reservoir of 100 mL of ascites was confirmed as the cut-off value in our cohort. A Kaplan-Meyer analysis with propensity score adjustments indicated that the accumulation of more than 100 mL of ascites shortened overall survival. The multivariate analysis revealed that the increased accumulation of 100 mL of ascites was an independent prognostic factor for overall survival (HR 1.242; 95% CI 1.050-1.470; P = 0.012). The subgroup analysis showed the prognostic significance of ascites accumulation in mucinous and endometrioid histologies.

CONCLUSIONS

The accumulation of even a low to intermediate volume of ascites (≥ 100 mL) was confirmed to be an independent poor prognostic factor in epithelial ovarian cancer. Furthermore, its prognostic impact differed among histotypes.

Research progress on animal models of peritoneal adhesion

Peritoneal adhesion is a common complication of abdominal and pelvic surgery that can cause various clinical symptoms, including abdominal pain, intestinal obstruction, and female infertility, significantly impacting patient quality of life. Animal models of peritoneal adhesion are important tools for studying the mechanisms of adhesion formation and evaluating the effectiveness of prevention and treatment. Various methods for constructing animal models of peritoneal adhesion include physical injury, chemical injury, ischemia, infection, foreign body stimulation, and simulated surgery; however, none can fully simulate peritoneal adhesion in patients clinically. Therefore, this review aimed to explore previous methods used to construct peritoneal adhesion animal models and summarize their principles, characteristics, and applications. Similarly, it summarizes macroscopic and microscopic evaluation indicators, such as peritoneal adhesion gross assessment, histological scoring, and molecular markers. On the basis of this, we proposed a new animal model of peritoneal adhesion that simulates the factors contributing to peritoneal adhesion formation in clinical surgery. peritoneal adhesion formation was stable and standardized using our proposed model, providing a foundation for the establishment and application of peritoneal adhesion animal models.

Impact of the uroperitoneum on the development of paralytic ileus: a preclinical study in the pig model

PURPOSE

The intraperitoneal leak of urine is considered as a major cause of peritoneal inflammatory reaction that could lead to paralytic ileus. Our aim was to document the effect of urine on the peritoneal surface.

METHODS

Seven white minipigs (one control-six tests) underwent standardized general anaesthesia. In three test pigs urine was aspirated from the bladder and instilled in the peritoneal cavity. In the remaining three pigs a continuous urine leak was created through section of the ureter. At 4 and 10 h laparoscopic harvesting of slices of the parietal peritoneum at the level of the Douglas pouch, lateral pelvic wall and subdiaphragmatic area was performed. Ileum slices were also obtained at 10 h. The slices were microscopically evaluated for inflammatory infiltrate (INI) of the peritoneum according to the Sydney system classification.

RESULTS

The presence of urine in the peritoneum induces distention of the ileum. At 4 h, a light-moderate INI was observed to two pigs of both test groups but not to the control pig. At 10 h a light-moderate INI appeared in the peritoneal slices of the control pig. Moreover, three out of six pigs of both test groups showed some degree of INI of the parietal peritoneum. The histologic evaluation of the slices of the distended ileum did not reveal INI.

CONCLUSIONS

The intraperitoneal urine induces distention of the bowel but no inflammation of the visceral peritoneum in the short term (10 h). Other than inflammation mechanisms through which the urine induces small ileum distention should be investigated.

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.

Reactive Changes in Lymph Node Structure in Peritonitis and during Treatment with a New Antibiotic

The effect of a new antibiotic peptomide A-70 on changes in the mesenterial lymph nodes caused by experimental peritonitis was studied. Differences in the morphological changes in rat lymph nodes in peritonitis and against the background of antibiotic therapy were revealed. Lymph nodes responded to peritoneal inflammation by reducing the area of cortical structures and expansion of the sinus system, which indicates a decrease in drainage-detoxification and immune function and determines unfavorable outcome of peritonitis. Antibiotic therapy reduced inflammatory manifestations and toxic pressure on the lymph system and potentiated the reactive response of the mesenteric lymph nodes: the size of lymphoid nodes and the paracortical T-dependent zone increased against the background of shrinkage of the sinus system, which attested to activation of the lymphopoietic function and immune response of lymph nodes in peritonitis. The observed changes attested to favorable prognosis of peritonitis treated with antibiotic peptomide A-70.

Visceral to subcutaneous fat area ratio predicts severe abdominal adhesions in definitive surgery for anastomotic fistula after small intestine resection

Abdominal adhesions manifests following abdominal infections triggered by intestinal fistulas. The severity of such adhesions depends on the extent of fiber deposition and peritoneal fibrinolysis following peritoneal injury, which may be influenced by sustained inflammation within the abdominal cavity. In this regard, the visceral-to-subcutaneous fat area (VFA/SFA) ratio has been implicated as a potential marker of inflammation. This study aimed to explore the relationship between VFA/SFA and abdominal adhesions. This multicenter study was conducted across four tertiary institutions and involved patients who had undergone definitive surgery (DS) for intestinal fistula from January 2009 and October 2023. The presence of abdominal adhesions was determined intraoperatively. VFA/SFA was investigated as a potential risk factor for severe adhesions. The study comprised 414 patients with a median age of 50 [interquartile range (IQR) 35-66] years and a median body mass index of 20.0 (IQR 19.2-22.4) kg/m2, including 231 males with a median VFA/SFA of 1.0 (IQR 0.7-1.2) and 183 females a median VFA/SFA of 0.8 (0.6-1.1). VFA/SFA was associated with severe abdominal adhesions in males [odds ratio (OR) = 3.34, 95% CI 1.14-9.80, p = 0.03] and females (OR = 2.99, 95% CI 1.05-8.53, p = 0.04). J-shaped association between VFA/SFA ratio and severe adhesions was revealed in both sex. The increasing trend can be revealed when OR more than 0.8, and 0.6 in males and females respectively. Preoperative VFA/SFA demonstrates predictive value for statues of severe abdominal adhesions in DS for anastomotic fistula after small intestine resection.

Human peritoneal fluid exerts ovulation- and nonovulation-sourced oncogenic activities on transforming fallopian tube epithelial cells

Secretory cells in the fallopian tube fimbria epithelium (FTE) are regarded as the main cells of origin of ovarian high-grade serous carcinoma (HGSC). Ovulation is the main cause of FTE oncogenesis, which proceeds through a sequence of TP53 mutations, chromosomal instability due to Rb/cyclin E aberration, in situ carcinoma (STIC), and metastasis to the ovary and peritoneum (metastatic HGSC). Previously, we have identified multiple oncogenic activities of the ovulatory follicular fluid (FF), which exerts the full spectrum of transforming activity on FTE cells at different stages of transformation. After ovulation, the FF is transfused into the peritoneal fluid (PF), in which the FTE constantly bathes. We wondered whether PF exerts the same spectrum of oncogenic activities as done by FF and whether these activities are derived from FF. By using a panel of FTE cell lines with p53 mutation (FT282-V), p53/CCNE1 aberrations (FT282-CCNE1), and p53/Rb aberrations plus spontaneous transformation, and peritoneal metastasis (FEXT2), we analyzed the changes of different transformation phenotypes after treating with FF and PF collected before or after ovulation. Similar to effects exhibited by FF, we found that, to a lesser extent, PF promoted anchorage-independent growth (AIG), migration, anoikis resistance, and peritoneal attachment in transforming FTE cells. The more transformed cells were typically more affected. Among the transforming activities exhibited by PF treatment, AIG, Matrigel invasion, and peritoneal attachment growth were higher with luteal-phase PF treatment than with the proliferative-phase PF treatment, suggesting an ovulation source. In contrast, changes in anoikis resistance and migration activities were similar in response to treatment with PF collected before and after ovulation, suggesting an ovulation-independent source. The overall transforming activity of luteal-phase PF was verified in an i.p. co-injection xenograft mouse model. Co-injection of Luc-FEXT2 cells with either FF or luteal-phase PF supported early peritoneal implantation, whereas co-injection with follicular-phase PF did not. This study, for the first time, demonstrates that PF from ovulating women can promote different oncogenic phenotypes in FTE cells at different stages of malignant transformation. Most of these activities, other than anoikis resistance and cell migration, are sourced from ovulation.

Sterile inflammation of peritoneal membrane caused by peritoneal dialysis: focus on the communication between immune cells and peritoneal stroma

Peritoneal dialysis is a widely used method for treating kidney failure. However, over time, the peritoneal structure and function can deteriorate, leading to the failure of this therapy. This deterioration is primarily caused by infectious and sterile inflammation. Sterile inflammation, which is inflammation without infection, is particularly concerning as it can be subtle and often goes unnoticed. The onset of sterile inflammation involves various pathological processes. Peritoneal cells detect signals that promote inflammation and release substances that attract immune cells from the bloodstream. These immune cells contribute to the initiation and escalation of the inflammatory response. The existing literature extensively covers the involvement of different cell types in the sterile inflammation, including mesothelial cells, fibroblasts, endothelial cells, and adipocytes, as well as immune cells such as macrophages, lymphocytes, and mast cells. These cells work together to promote the occurrence and progression of sterile inflammation, although the exact mechanisms are not fully understood. This review aims to provide a comprehensive overview of the signals from both stromal cells and components of immune system, as well as the reciprocal interactions between cellular components, during the initiation of sterile inflammation. By understanding the cellular and molecular mechanisms underlying sterile inflammation, we may potentially develop therapeutic interventions to counteract peritoneal membrane damage and restore normal function.

Tissue Options for Construction of the Neovaginal Canal in Gender-Affirming Vaginoplasty

Gender-affirming vaginoplasty (GAV) comprises the construction of a vulva and a neovaginal canal. Although technical nuances of vulvar construction vary between surgeons, vulvar construction is always performed using the homologous penile and scrotal tissues to construct the corresponding vulvar structures. Therefore, the main differentiating factor across gender-affirming vaginoplasty techniques is the tissue that is utilized to construct the neovaginal canal. These tissue types vary markedly in their availability, histology, and ease of harvest and have different advantages and disadvantages to their use as neovaginal lining. In this narrative review, the authors provide a comprehensive overview of the tissue types and associated operative approaches used for construction of the neovagina in GAV. Tissue choice is guided by several factors, such as histological similarity to natal vaginal mucosa, tissue availability, lubrication potential, additional donor site morbidity, and the specific goals of each patient. Skin is used to construct the neovagina in most cases with a combination of pedicled penile skin flaps and scrotal and extra-genital skin grafts. However, skin alternatives such as peritoneum and intestine are increasing in use. Peritoneum and intestine are emerging as options for primary vaginoplasty in cases of limited genital skin or revision vaginoplasty procedures. The increasing number of gender-affirming vaginoplasty procedures performed and the changing patient demographics from factors such as pubertal suppression have resulted in rapidly evolving indications for the use of these differing vaginoplasty techniques. This review sheds light on the use of less frequently utilized tissue types described for construction of the neovaginal canal, including mucosal tissues such as urethral and buccal mucosa, the tunica vaginalis, and dermal matrix allografts and xenografts. Although the body of evidence for each vaginoplasty technique is growing, there is a need for large prospective comparison studies of outcomes between these techniques and the tissue types used to line the neovaginal canal to better define indications and limitations.

Reciprocal crosstalk between Th17 and mesothelial cells promotes metastasis-associated adhesion of ovarian cancer cells

BACKGROUND

IL-17A and TNF synergistically promote inflammation and tumorigenesis. Their interplay and impact on ovarian carcinoma (OC) progression are, however, poorly understood. We addressed this question focusing on mesothelial cells, whose interaction with tumor cells is known to play a pivotal role in transcoelomic metastasis formation.

METHODS

Flow-cytometry and immunohistochemistry experiments were employed to identify cellular sources of IL-17A and TNF. Changes in transcriptomes and secretomes were determined by bulk and single cell RNA sequencing as well as affinity proteomics. Functional consequences were investigated by microscopic analyses and tumor cell adhesion assays. Potential clinical implications were assessed by immunohistochemistry and survival analyses.

RESULTS

We identified Th17 cells as the main population of IL-17A- and TNF producers in ascites and detected their accumulation in early omental metastases. Both IL-17A and its receptor subunit IL-17RC were associated with short survival of OC patients, pointing to a role in clinical progression. IL-17A and TNF synergistically induced the reprogramming of mesothelial cells towards a pro-inflammatory mesenchymal phenotype, concomitantly with a loss of tight junctions and an impairment of mesothelial monolayer integrity, thereby promoting cancer cell adhesion. IL-17A and TNF synergistically induced the Th17-promoting cytokines IL-6 and IL-1β as well as the Th17-attracting chemokine CCL20 in mesothelial cells, indicating a reciprocal crosstalk that potentiates the tumor-promoting role of Th17 cells in OC.

CONCLUSIONS

Our findings reveal a novel function for Th17 cells in the OC microenvironment, which entails the IL-17A/TNF-mediated induction of mesothelial-mesenchymal transition, disruption of mesothelial layer integrity and consequently promotion of OC cell adhesion. These effects are potentiated by a positive feedback loop between mesothelial and Th17 cells. Together with the observed clinical associations and accumulation of Th17 cells in omental micrometastases, our observations point to a potential role in early metastases formation and thus to new therapeutic options.

Intercellular communication in peritoneal dialysis

Long-term peritoneal dialysis (PD) causes structural and functional alterations of the peritoneal membrane. Peritoneal deterioration and fibrosis are multicellular and multimolecular processes. Under stimulation by deleterious factors such as non-biocompatibility of PD solution, various cells in the abdominal cavity show differing characteristics, such as the secretion of different cytokines, varying protein expression levels, and transdifferentiation into other cells. In this review, we discuss the role of various cells in the abdominal cavity and their interactions in the pathogenesis of PD. An in-depth understanding of intercellular communication and inter-organ communication in PD will lead to a better understanding of the pathogenesis of this disease, enabling the development of novel therapeutic targets.

Impact of Standard Versus Low Pneumoperitoneum Pressure on Peritoneal Environment in Laparoscopic Cholecystectomy. Randomized Clinical Trial

BACKGROUND

High CO 2 pneumoperitoneum pressure during laparoscopy adversely affects the peritoneal environment. This study hypothesized that low pneumoperitoneum pressure may be linked to less peritoneal damage and possibly to better clinical outcomes.

MATERIALS AND METHODS

One hundred patients undergoing scheduled laparoscopic cholecystectomy were randomized 1:1 to low or to standard pneumoperitoneum pressure. Peritoneal biopsies were performed at baseline time and 1 hour after peritoneum insufflation in all patients. The primary outcome was peritoneal remodeling biomarkers and apoptotic index. Secondary outcomes included biomarker differences at the studied times and some clinical variables such as length of hospital stay, and quality and safety issues related to the procedure.

RESULTS

Peritoneal IL6 after 1 hour of surgery was significantly higher in the standard than in the low-pressure group (4.26±1.34 vs. 3.24±1.21; P =0.001). On the contrary, levels of connective tissue growth factor and plasminogen activator inhibitor-I were higher in the low-pressure group (0.89±0.61 vs. 0.61±0.84; P =0.025, and 0.74±0.89 vs. 0.24±1.15; P =0.028, respectively). Regarding apoptotic index, similar levels were found in both groups and were 44.0±10.9 and 42.5±17.8 in low and standard pressure groups, respectively. None of the secondary outcomes showed differences between the 2 groups.

CONCLUSIONS

Peritoneal inflammation after laparoscopic cholecystectomy is higher when surgery is performed under standard pressure. Adhesion formation seems to be less in this group. The majority of patients undergoing surgery under low pressure were operated under optimal workspace conditions, regardless of the surgeon's expertise.

Intraperitoneal administration of carcinoembryonic antigen-directed chimeric antigen receptor T cells is a robust delivery route for effective treatment of peritoneal carcinomatosis from colorectal cancer in pre-clinical study

BACKGROUND AIMS

Peritoneal carcinomatosis (PC) from colorectal cancer (CRC) is a highly challenging disease to treat. Systemic chimeric antigen receptor (CAR) T cells have shown impressive efficacy in hematologic malignancies but have been less effective in solid tumors. We explored whether intraperitoneal (i.p.) administration of CAR T cells could provide an effective and robust route of treatment for PC from CRC.

METHODS

We generated second-generation carcinoembryonic antigen (CEA)-specific CAR T cells. Various animal models of PC with i.p. and extraperitoneal metastasis were treated by i.p. or intravenous (i.v.) administration of CEA CAR T cells.

RESULTS

Intraperitoneally administered CAR T cells exhibited superior anti-tumor activity compared with systemic i.v. cell infusion in an animal model of PC. In addition, i.p. administration conferred a durable effect and protection against tumor recurrence and exerted strong anti-tumor activity in an animal model of PC with metastasis in i.p. or extraperitoneal organs. Moreover, compared with systemic delivery, i.p. transfer of CAR T cells provided increased anti-tumor activity in extraperitoneal tumors without PC. This phenomenon was further confirmed in an animal model of pancreatic carcinoma after i.p. administration of our newly constructed prostate stem cell antigen-directed CAR T cells.

CONCLUSIONS

Taken together, our data suggest that i.p. administration of CAR T cells may be a robust delivery route for effective treatment of cancer.

The complex role of IL-10 in malignant ascites: a review

The emergence of malignant ascites (MA) indicates poor prognoses in patients with ovarian, gastrointestinal, breast, and pancreatic cancer. Interleukin-10 (IL-10) is a pleiotropic cytokine with immunoregulatory effects in tumor microenvironment. The level of IL-10 in MA varied across cancer types and patients, influencing cancer progression and outcomes. Originating from various immune and cancer cells, IL-10 contributes to complex signaling pathways in MA. Systemic IL-10 administration, although the evidence of its efficacy on MA is limited, still emerges as a promising therapeutic strategy because it can increase CD8+ T cells cytotoxicity and invigorate exhausted CD8+ tumor infiltration lymphocytes (TILs) directly. IL-10 signaling blockade also demonstrates great potential when combined with other immunotherapies in MA treatment. We reviewed the levels, origins, and functions of IL-10 in malignant ascites and overviewed the current IL-10 signaling targeting therapies, aiming to provide insights for MA treatment.

Advances in the treatment of malignant ascites in China

PURPOSE

Malignant ascites (MA) often occurs in recurrent abdominal malignant tumors, and the large amount of ascites associated with cancerous peritonitis not only leads to severe abdominal distension and breathing difficulties, but also reduces the patient's quality of life and ability to resist diseases, which usually makes it difficult to carry out anti-cancer treatment. The exploration of MA treatment methods is also a key link in MA treatment. This article is going to review the treatment of MA, to provide details for further research on the treatment of MA, and to provide some guidance for the clinical treatment of MA.

METHOD

This review analyzes various expert papers and summarizes them to obtain the paper.

RESULT

There are various treatment methods for MA, including systemic therapy and local therapy. Among them, systemic therapy includes diuretic therapy, chemotherapy, immunotherapy, targeted therapy, anti angiogenic therapy, CAR-T, and vaccine. Local therapy includes puncture surgery, peritoneal vein shunt surgery, acellular ascites infusion therapy, radioactive nuclide intraperitoneal injection therapy, tunnel catheter, and intraperitoneal hyperthermia chemotherapy. And traditional Chinese medicine treatment has also played a role in enhancing efficacy and reducing toxicity to a certain extent.

CONCLUSION

Although there has been significant progress in the treatment of MA, it is still one of the clinical difficulties. Exploring the combination or method of drugs with the best therapeutic effect and the least adverse reactions to control MA is still an urgent problem to be solved.

[Description of a vaginoplasty technique using a peritoneal flap harvested by coelioscopic approach for male-to-female gender affirmations (MtF)]

AIM

The aim of this article is to provide a comprehensive description of the peritoneal flap technique in male-to-female (MtF) gender affirmation surgery, particularly in cases of insufficient depth after penile inversion vaginoplasty.

RESULTS

Our short-term results reveal that the peritoneal flap vaginoplasty, adapted from the Davydov procedure, has shown significant potential for improving functional and aesthetic outcomes, including the creation of a self-lubricating neovagina. However, the complexity of the procedure requires advanced surgical expertise and appropriate postoperative care. Patient selection also plays an essential role as not all patients are ideal candidates for this procedure.

CONCLUSION

Despite its promises, the widespread adoption of the peritoneal flap technique in male-to-female (MtF) gender affirmation surgery is hindered by several challenges, including the need for specialized training and potential postoperative complications. Thus, this technique should be considered as an alternative or complement to traditional methods, depending on individual patient factors. Further research and extensive clinical trials are needed to better understand its potential and limitations in order to enhance the arsenal of effective surgical options for MtF gender affirmation surgery.

Techniques for navigating postsurgical adhesions: Insights into mechanisms and future directions

Postsurgical adhesions are a common complication of surgical procedures that can lead to postoperative pain, bowel obstruction, infertility, as well as complications with future procedures. Several agents have been developed to prevent adhesion formation, such as barriers, anti-inflammatory and fibrinolytic agents. The Food and Drug Administration (FDA) has approved the use of physical barrier agents, but they have been associated with conflicting clinical studies and controversy in the clinical utilization of anti-adhesion barriers. In this review, we summarize the human anatomy of the peritoneum, the pathophysiology of adhesion formation, the current prevention agents, as well as the current research progress on adhesion prevention. The early cellular events starting with injured mesothelial cells and incorporating macrophage response have recently been found to be associated with adhesion formation. This may provide the key component for developing future adhesion prevention methods. The current use of physical barriers to separate tissues, such as Seprafilm®, composed of hyaluronic acid and carboxymethylcellulose, can only reduce the risk of adhesion formation at the end stage. Other anti-inflammatory or fibrinolytic agents for preventing adhesions have only been studied within the context of current research models, which is limited by the lack of in-vitro model systems as well as in-depth study of in-vivo models to evaluate the efficiency of anti-adhesion agents. In addition, we explore emerging therapies, such as gene therapy and stem cell-based approaches, that may offer new strategies for preventing adhesion formation. In conclusion, anti-adhesion agents represent a promising approach for reducing the burden of adhesion-related complications in surgical patients. Further research is needed to optimize their use and develop new therapies for this challenging clinical problem.

Malignant ascites: Current therapy options and treatment prospects

Ascites formation is a common complication of cancer with a significant symptomatic burden for patients. Malignant ascites (MA) is defined by the presence of tumor cells within the ascitic fluid. It does not only cause substantial morbidity, but is also associated with impaired survival. Considering the frequent occurrence of MA, it still represents a clinical challenge for physicians with limited therapy options, mainly comprising of the treatment of the primary tumor and effusion drainage. Particularly the lack of pathophysiological insight limits the development of effective, causative therapies. Causes of MA development such as lymphatic vessel obstruction and the effects of tumor secreted vascular endothelial growth factor (VEGF) have been known for decades. Novel research suggests that the intraperitoneal immune system may also induce and maintain MA accumulation. In this review, we assess current knowledge on the pathophysiology of MA and summarize available evidence of treatment approaches. Also, factors contributing to ascites formation without proof of tumor cells in the peritoneal cavity, defined as paramalignant ascites, with potential treatment strategies are discussed. We further focus on novel findings in the pathophysiology of MA that might lead to treatment improvement in the near future and discussed relevant knowledge gaps in this field.

The effect of electrostatic high pressure nebulization on the stability, activity and ex vivo distribution of ionic self-assembled nanomedicines

Pressurized intraperitoneal aerosol chemotherapy (PIPAC) is applied to treat unresectable peritoneal metastasis (PM), an advanced, end-stage disease with a poor prognosis. Electrostatic precipitation of the aerosol (ePIPAC) is aimed at improving the intraperitoneal (IP) drug distribution and tumor penetration. Also, the combination of nanoparticles (NPs) as drug delivery vehicles and IP aerosolization as administration method has been proposed as a promising tool to treat PM. There is currently limited knowledge on how electrostatic precipitation (ePIPAC) and high pressure nebulization (PIPAC) affects the performance of electrostatically formed complexes. Therefore, the stability, in vitro activity and ex vivo distribution and tissue penetration of negatively charged cisPt-pArg-HA NPs and positively charged siRNA-RNAiMAX NPs was evaluated following PIPAC and ePIPAC. Additionally, a multidirectional Medspray® nozzle was developed and compared with the currently used Capnopen® nozzle. For both NP types, PIPAC and ePIPAC did not negatively influence the in vitro activity, although limited aggregation of siRNA-RNAiMAX NPs was observed following nebulization with the Capnopen®. Importantly, ePIPAC was linked to a more uniform distribution and higher tissue penetration of the NPs aerosolized by both nozzles, independent on the NPs charge. Finally, compared to the Capnopen®, an increased NP deposition was observed at the top of the ex vivo model following aerosolization with the Medspray® nozzle, which indicates that this device possesses great potential for IP drug delivery purposes. STATEMENT OF SIGNIFICANCE: Aerosolized drug delivery in the peritoneal cavity holds great promise to treat peritoneal cancer. In addition, electrostatic precipitation of the aerosol to the peritoneal tissue is aimed at improving the drug distribution and tumor penetration. The combination of nanoparticles (NPs), which are nano-sized drug delivery vehicles, and aerosolization has been proposed as a promising tool to treat peritoneal cancer. However, there is currently limited knowledge on how electrostatic precipitation and aerosolization affect the performance of electrostatically formed NPs. Therefore, the stability, activity, distribution and penetration of negatively and positively charged NPs was evaluated after aerosolization and electrostatic precipitation. Additionally, to further optimize the local drug distribution, a multidirectional spray nozzle was developed and compared with the currently used nozzle.

Smart hydrogels delivered by high pressure aerosolization can prevent peritoneal adhesions

Postoperative peritoneal adhesions occur in the majority of patients undergoing intra-abdominal surgery and are one of the leading causes of hospital re-admission. There is an unmet clinical need for effective anti-adhesive biomaterials, which can be applied evenly across the damaged tissues. We examined three different responsive hydrogel types, i.e. a thermosensitive PLGA-PEG-PLGA, a pH responsive UPy-PEG and a shear-thinning hexapeptide for this purpose. More specifically, their potential to be homogeneously distributed in the peritoneal cavity by high pressure nebulization and prevent peritoneal adhesions was evaluated. Solutions of each polymer type could be successfully nebulized while retaining their responsive gelation behavior in vitro and in vivo. Furthermore, none of the polymers caused in vitro toxicity on SKOV3-IP2 cells. Following intraperitoneal administration, both the PLGA-PEG-PLGA and the hexapeptide hydrogels resulted in local inflammation and fibrosis and failed in preventing peritoneal adhesions 7 days after adhesion induction. In contrast, the pH sensitive UPy-PEG formulation was well tolerated and could significantly reduce the formation of peritoneal adhesions, even outperforming the commercially available Hyalobarrier® as positive control. To conclude, local nebulization of the bioresponsive UPy-PEG hydrogel can be considered as a promising approach to prevent postsurgical peritoneal adhesions.

Clinical Outcomes after the Use of Antiadhesive Agents in Laparoscopic Reproductive Surgery

INTRODUCTION

Intra-abdominal adhesions are abnormal fibrous attachments between tissues and organs that can be congenital or acquired. Adhesion formation is a critical postoperative complication that may lead to bowel obstruction, chronic abdominal pain, and infertility. Physical barrier agents separate opposing peritoneal surfaces in the critical 5-day period of remesotheliazation. These agents are subdivided into solid or liquid/gel. Liquid agents seem easier to use in laparoscopic procedures than solid agents.

METHODS

The search for suitable articles published in English was carried out using the following databases: MEDLINE, Embase, Global Health, the Cochrane Library (Cochrane Database of Systematic Reviews, Cochrane Central Register of Controlled Trials, Cochrane Methodology Register), Health Technology Assessment Database, Web of Science, and search register (ClinicalTrial.gov). Only studies reporting data about the impact of the use of an antiadhesive agent on adhesion formation after a primary gynecologic laparoscopic surgery were considered eligible.

RESULTS

Twenty-two papers that met the inclusion criteria were included in this systematic review.

CONCLUSIONS

Surgeons should consider applying antiadhesive agents after gynecologic surgery to help reduce adhesion formation and its adverse effects. However, further studies are still needed to confirm their impact on reproductive outcome and to implement clear guidelines on their per-operative application.

Malignant Peritoneal Mesothelioma: An In-Depth and Up-to-Date Review of Pathogenesis, Diagnosis, Management and Future Directions

Malignant peritoneal mesothelioma (MPM) is an extremely rare malignancy usually confined to the abdominal cavity. With an aggressive natural history, morbidity and mortality are consequences of progressive locoregional effects within the peritoneal cavity. The first reported case was in the early 20th century, however, due to the rare nature of the disease and a large gap in understanding of the clinicopathological effects, the next reported MPM cases were only published half a decade later. Since then, there has been exponential growth in our understanding of the disease, however, there are no prospective data and a paucity of literature regarding management. Traditionally, patients were treated with systemic therapy and the outcomes were very poor, with a median survival of less than one year. However, with the advent of cytoreductive surgery and locoregional chemotherapy, there have been significant improvements in survival. Even more recently, with an improved understanding of the molecular pathogenesis of MPM, there have been reports of improved outcomes with novel therapies. Given the disastrous natural history of MPM, the limited data, and the lack of universal treatment guidelines, an in-depth review of the past, present, and future of MPM is critical to improve treatment regimens and, subsequently, patient outcomes.

MicroRNAs Can Influence Ovarian Cancer Progression by Dysregulating Integrin Activity

Ovarian cancer is a deadly disease that affects thousands of women worldwide. Integrins, transmembrane receptors that mediate cell adhesion and signaling, play important roles in ovarian cancer progression, metastasis, and drug resistance. Dysregulated expression of integrins is implicated in various cellular processes, such as cell migration, invasion, and proliferation. Emerging evidence suggests that microRNAs (miRNAs) can regulate integrin expression and function, thus affecting various physiological and pathological processes, including ovarian cancer. In this article, we review the current understanding of integrin-mediated cellular processes in ovarian cancer and the roles of miRNAs in regulating integrins. We also discuss the therapeutic potential of targeting miRNAs that regulate integrins for the treatment of ovarian cancer. Targeting miRNAs that regulate integrins or downstream signaling pathways of integrins may provide novel therapeutic strategies for inhibiting integrin-mediated ovarian cancer progression.

Effects of Hyperthermia and Hyperthermic Intraperitoneal Chemoperfusion on the Peritoneal and Tumor Immune Contexture

Hyperthermia combined with intraperitoneal (IP) drug delivery is increasingly used in the treatment of peritoneal metastases (PM). Hyperthermia enhances tumor perfusion and increases drug penetration after IP delivery. The peritoneum is increasingly recognized as an immune-privileged organ with its own distinct immune microenvironment. Here, we review the immune landscape of the healthy peritoneal cavity and immune contexture of peritoneal metastases. Next, we review the potential benefits and unwanted tumor-promoting effects of hyperthermia and the associated heat shock response on the tumor immune microenvironment. We highlight the potential modulating effect of hyperthermia on the biomechanical properties of tumor tissue and the consequences for immune cell infiltration. Data from translational and clinical studies are reviewed. We conclude that (mild) hyperthermia and HIPEC have the potential to enhance antitumor immunity, but detailed further studies are required to distinguish beneficial from tumor-promoting effects.

A Potential Resuscitation Route on Battlefield: Immediate Intraperitoneal Fluid Administration Post-burn Shows Satisfactory Fluid Absorption and Anti-shock Effects

INTRODUCTION

Timely fluid resuscitation remains the key to the early treatment of severe burns. Intraperitoneal (IP) fluid administration is a simple, rapid resuscitation strategy via a puncture in the abdominal wall. This study aimed to evaluate the fluid absorption and anti-shock effects of IP delivery in the early stage after severe burns.

MATERIALS AND METHODS

A 30% total body surface area full-thickness burn model was established using male C57BL/6 mice. A total of 126 mice were randomly assigned into six groups (n = 21): the sham injury group (SHAM), the burn group without fluid resuscitation (NR), and the four IP resuscitation groups (IP-A/B/C/D, each being intraperitoneally administered with 60, 80, 100, and 120 mL/kg of sodium lactate Ringer's solution post-injury). Three-hour post-burn, six mice in each group were randomly selected and sacrificed for blood and tissue sampling to detect the IP fluid absorption rate and evaluate organ damage because of low perfusion. The remaining 15 mice in each group were observed for the vital signs within 48-h post-injury, and their survival rate was calculated.

RESULTS

The 48-h survival rate increased in the IP-A (40.0%), IP-B (66.7%), IP-C (60.0%), and IP-D (13.3%) groups, compared with the NR group (0%). The mean arterial pressure, body temperature, and heart rate of mice were significantly stabilized in the IP groups. For the first 3-h post-injury, the absorption rates of groups IP-A (74.3% ± 9.5%) and IP-B (73.3% ± 6.9%) were significantly higher than those of groups IP-C (59.7% ± 7.1%) and IP-D (48.7% ± 5.7%). The levels of arterial blood pH, partial pressure of oxygen, partial pressure of carbon dioxide, lactate, and hematocrit were better maintained in the IP groups. Intraperitoneal resuscitation remarkably reduced the injury scores in burn-induced histopathology of the liver, kidneys, lungs, and intestines, accompanied by decreased alanine transaminase, creatinine, interleukin-1, and tumor necrosis factor-α in plasma, and augmented superoxide dismutase 2 and inhibited malondialdehyde in tissues. Group IP-B has the best performance for these indices.

CONCLUSIONS

Intraperitoneal administration of isotonic saline post-burn can be adequately and rapidly absorbed, thereby boosting circulation and perfusion, precluding shock, alleviating organ damage caused by ischemia and hypoxia, and significantly increasing the survival rate. This technique, with a potential to be a supplement to existing resuscitation methods on the battlefield, is worth further investigation.

Functional biomaterials for the diagnosis and treatment of peritoneal surface malignancies

Peritoneal surface malignancies (PSM) can originate from tumors in many organs and are highly malignant, and difficult to diagnose and cure, posing a serious threat to the survival of patients. Although the diagnosis and treatment of PSM have made significant progress in the past two decades, numerous challenges remain. Recently, functionalized biomaterials have shown promise for PSM diagnosis and treatment. Hence, we review the progress of functionalized biomaterials for the diagnosis and treatment of PSM. We first introduce the classification and pathogenesis of PSM. We then discuss the applications of functionalized biomaterials for the diagnosis and treatment of PSM. In particular, we focus on functionalized biomaterials as drug carriers for the treatment of PSM, including chemotherapy, immunotherapy, targeted therapy, combination therapy, and other therapies. Finally, we summarized the current challenges and provided a perspective on the diagnosis and treatment of PSM.

Factors Associated with Complications after Total Pharyngo-Laryngo-Esophagectomy and Free Jejunal Flap Reconstruction

INTRODUCTION

Free jejunal flap (FJF) reconstruction is a standard procedure for pharyngeal and cervical esophageal defects resulting from head and neck cancer resection. However, improvements in patients' quality of life after surgery require a further statistical approach.

METHODS

An observational, retrospective, multivariate analysis was designed to report the incidence of postoperative complications and their association with clinical factors in 101 patients who underwent total pharyngo-laryngo-esophagectomy and FJF reconstruction for head and neck cancer at a university hospital between January 2007 and December 2020.

RESULTS

Postoperative complications were observed in 69% of patients. In the reconstructive site, anastomotic leak, observed in 8% of patients was associated with vascular anastomosis in the external jugular vein system (age-adjusted odds ratio [OR]: 9.05, p = 0.044) and anastomotic stricture, observed in 11% of patients was associated with postoperative radiotherapy (age-adjusted OR: 12.60, p = 0.02). Cervical skin flap necrosis was the most common complication (34%) and was associated with vascular anastomosis on the right cervical side (age- and sex-adjusted OR: 4.00, p = 0.005).

CONCLUSION

Although FJF reconstruction is a useful procedure, 69% of patients suffer a postoperative complication. We suppose that anastomotic leak is related to the low blood flow resistance of the FJF and inadequate drainage of the external jugular venous system, and anastomotic stricture is related to the vulnerability of the intestinal tissue to radiation. Furthermore, we hypothesized that the location of the vascular anastomosis may affect the mesenteric location of the FJF and the dead space in the neck, leading to the development of cervical skin flap necrosis. These data contribute to increasing our knowledge about postoperative complications related to FJF reconstruction.

Intraperitoneal anatomy with the aid of pathologic fluid and gas: An imaging pictorial review

The peritoneum is a large serosal membrane enveloping the abdomen and pelvic organs and forming the peritoneal cavity. This complex relationship forms many named abdominopelvic spaces, which are frequently involved in infectious, inflammatory, neoplastic, and traumatic pathologies. The knowledge of this anatomy is essential to the radiologist to localize and describe the extent of the disease accurately. This manuscript provides a comprehensive pictorial review of the peritoneal anatomy to describe pathologic fluid and gas.

Targeting Oncometabolites in Peritoneal Cancers: Preclinical Insights and Therapeutic Strategies

Peritoneal cancers present significant clinical challenges with poor prognosis. Understanding the role of cancer cell metabolism and cancer-promoting metabolites in peritoneal cancers can provide new insights into the mechanisms that drive tumor progression and can identify novel therapeutic targets and biomarkers for early detection, prognosis, and treatment response. Cancer cells dynamically reprogram their metabolism to facilitate tumor growth and overcome metabolic stress, with cancer-promoting metabolites such as kynurenines, lactate, and sphingosine-1-phosphate promoting cell proliferation, angiogenesis, and immune evasion. Targeting cancer-promoting metabolites could also lead to the development of effective combinatorial and adjuvant therapies involving metabolic inhibitors for the treatment of peritoneal cancers. With the observed metabolomic heterogeneity in cancer patients, defining peritoneal cancer metabolome and cancer-promoting metabolites holds great promise for improving outcomes for patients with peritoneal tumors and advancing the field of precision cancer medicine. This review provides an overview of the metabolic signatures of peritoneal cancer cells, explores the role of cancer-promoting metabolites as potential therapeutic targets, and discusses the implications for advancing precision cancer medicine in peritoneal cancers.

Vaginal self-lubrication following peritoneal, penile inversion, and colonic gender-affirming vaginoplasty: a physiologic, anatomic, and histologic review

INTRODUCTION

Vaginal self-lubrication is central to the sexual satisfaction and healthy genitourinary function of patients who have undergone gender-affirming vaginoplasty (GAV). Secretory capacities of different neovaginal lining tissues have been variably described in the literature, with little evidence-based consensus on their success in providing a functionally self-lubricating neovagina. We review the existing neovaginal lubrication data and the anatomy, histology, and physiology of penile and scrotal skin, colon, and peritoneum to better characterize their capacity to be functionally self-lubricating when used as neovaginal lining.

OBJECTIVES

The study sought to review and compare the merits of penile and scrotal skin grafts, spatulated urethra, colon, and peritoneal flaps to produce functional lubrication analogous to that of the natal vagina in the setting of GAV.

METHODS

We conducted a systematic review following PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines. Medline, EMBASE, ClinicalTrials.gov, and the Cochrane Library databases were searched for peer-reviewed studies published prior to December 12, 2022, that (1) included data specific to transfeminine individuals; (2) were full-text randomized controlled studies, case reports, case series, retrospective cohort studies, prospective cohort studies, qualitative studies, and cross-sectional studies; and (3) included specific discussion of vaginal lubrication or fluid secretion following GAV utilizing penile skin, colonic tissue, or peritoneum.

RESULTS

We identified 580 studies, of which 28 met our inclusion criteria. Data on neovaginal lubrication were limited to qualitative clinician observations, patient-reported outcomes, and satisfaction measures. No studies quantifying neovaginal secretions were identified for any GAV graft or flap technique. Anatomically, penile and scrotal skin have no self-lubricating potential, though penile inversion vaginoplasty may produce some sexually responsive secretory fluid when urethral tissue is incorporated and lubricating genitourinary accessory glands are retained. Colonic and peritoneal tissues both have secretory capacity, but fluid production by these tissues is continuous, nonresponsive to sexual arousal, and likely inappropriate in volume, and so may not meet the needs or expectations of some patients. The impact of surgical tissue translocation on their innate secretory function has not been documented.

CONCLUSIONS

None of penile/scrotal skin, colon, or peritoneum provides functional neovaginal lubrication comparable to that of the adult natal vagina. Each tissue has limitations, particularly with respect to inappropriate volume and/or chronicity of secretions. The existing evidence does not support recommending one GAV technique over others based on lubrication outcomes. Finally, difficulty distinguishing between physiologic and pathologic neovaginal fluid secretion may confound the assessment of neovaginal self-lubrication, as many pathologies of the neovagina present with symptomatic discharge.

Mouse Tissue-Resident Peritoneal Macrophages in Homeostasis, Repair, Infection, and Tumor Metastasis

Large peritoneal macrophages (LPMs) are long-lived, tissue-resident macrophages, formed during embryonic life, developmentally and functionally confined to the peritoneal cavity. LPMs provide the first line of defense against life-threatening pathologies of the peritoneal cavity, such as abdominal sepsis, peritoneal metastatic tumor growth, or peritoneal injuries caused by trauma, or abdominal surgery. Apart from their primary phagocytic function, reminiscent of primitive defense mechanisms sustained by coelomocytes in the coelomic cavity of invertebrates, LPMs fulfill an essential homeostatic function by achieving an efficient clearance of apoptotic, that is crucial for the maintenance of self-tolerance. Research performed over the last few years, in mice, has unveiled the mechanisms by which LPMs fulfill a crucial role in repairing peritoneal injuries and controlling microbial and parasitic infections, reflecting that the GATA6-driven LPM transcriptional program can be modulated by extracellular signals associated with pathological conditions. In contrast, recent experimental evidence supports that peritoneal tumors can subvert LPM metabolism and function, leading to the acquisition of a tumor-promoting potential. The remarkable functional plasticity of LPMs can be nevertheless exploited to revert tumor-induced LPM protumor potential, providing the basis for the development of novel immunotherapeutic approaches against peritoneal tumor metastasis based on macrophage reprogramming.

Increased levels of NETosis biomarkers in high-grade serous ovarian cancer patients' biofluids: Potential role in disease diagnosis and management

Introduction

High-grade serous ovarian cancer (HGSOC) is the second most frequent gynecological malignancy but the most lethal, partially due to the spread of the disease through the peritoneal cavity. Recent evidence has shown that, apart from their role in immune defense through phagocytosis and degranulation, neutrophils are able to participate in cancer progression through the release of neutrophil extracellular traps (NETs) in a process called NETosis. NETs are composed of DNA, histones, calprotectin, myeloperoxidase (MPO) and elastase and the NETosis process has been proposed as a pre-requisite for the establishment of omental metastases in early stages of HGSOC. Nevertheless, its role in advanced stages remains to be elucidated. Therefore, our principal aim is to characterize a NETosis biomarker profile in biofluids from patients with advanced HGSOC and control women.

Methods

Specifically, five biomarkers of NETosis (cell-free DNA (cfDNA), nucleosomes, citrullinated histone 3 (citH3), calprotectin and MPO) were quantified in plasma and peritoneal fluid (PF) samples from patients (n=45) and control women (n=40).

Results

Our results showed that HGSOC patients presented a higher concentration of cfDNA, citH3 and calprotectin in plasma and of all five NETosis biomarkers in PF than control women. Moreover, these biomarkers showed a strong ability to differentiate the two clinical groups. Interestingly, neoadjuvant treatment (NT) seemed to reduce NETosis biomarkers mainly systemically (plasma) compared to the tumor environment (PF).

Discussion

In conclusion, NETosis biomarkers are present in the tumor environment of patients with advanced HGSOC, which might contribute to the progression of the disease. Besides, plasma cfDNA and calprotectin could represent minimally invasive surrogate biomarkers for HGSOC. Finally, NT modifies NETosis biomarkers levels mainly at the systemic level.

İntrabdominal Adezyon Oluşum Mekanizmalarına ve Tedavi Stratejilerine Histopatolojik Bakış

Hayat standartlarını olumsuz etkileyen abdominal adezyonlar, postoperatif dönemde görülen önemli bir sağlık sorunudur. Peritoneal kavite ve serozal yüzeylerde oluşan, abdominal travmalara sebep olan kimyasal ve termal faktörler ya da enfeksiyon ve yabancı cisim reaksiyonları adezyon oluşumuna sebep olabilir. Abdominal adezyonların sınıflandırması genellikle adezyon yoğunluğuna ve prognoz ciddiyetine göre yapılsa da henüz dünya çapında kabul görmüş standart bir sınıflandırma sistemi mevcut değildir. Abdominal adezyonlar ağrı, infertilite, cerrahi sonrası hastanede yatış süresinin uzaması ve ekonomik yük gibi olumsuz sonuçlarla klinik yansımalar gösterir. Sonuç olarak, postoperatif süreçte karşılaşılan adezyonlar ciddi bir sorundur ve adezyon oluşumunu engellemek için ileri çalışmaların laboratuvar ortamından klinik araştırma modellerine uyarlanması gerekmektedir. Bu derleme çalışması intraabdominal adezyon oluşumu, histopatolojisi, derecelendirilmesi, önlenmesi ve klinik önemi ile ilgili literatürü gözden geçirmek için hazırlanmıştır.

The metastatic capacity of high-grade serous ovarian cancer cells changes along disease progression: inhibition by mifepristone

BACKGROUND

Simplistic two-dimensional (2D) in vitro assays have long been the standard for studying the metastatic abilities of cancer cells. However, tri-dimensional (3D) organotypic models provide a more complex environment, closer to that seen in patients, and thereby provide a more accurate representation of their true capabilities. Our laboratory has previously shown that the antiprogestin and antiglucocorticoid mifepristone can reduce the growth, adhesion, migration, and invasion of various aggressive cancer cells assessed using 2D assays. In this study, we characterize the metastatic capabilities of high-grade serous ovarian cancer cells generated along disease progression, in both 2D and 3D assays, and the ability of cytostatic doses of mifepristone to inhibit them.

METHODS

High-grade serous ovarian cancer cells collected from two separate patients at different stages of their disease were used throughout the study. The 2D wound healing and Boyden chamber assays were used to study migration, while a layer of extracellular matrix was added to the Boyden chamber to study invasion. A 3D organotypic model, composed of fibroblasts embedded in collagen I and topped with a monolayer of mesothelial cells was used to further study cancer cell adhesion and mesothelial displacement. All assays were studied in cells, which were originally harvested from two patients at different stages of disease progression, in the absence or presence of cytostatic doses of mifepristone.

RESULTS

2D in vitro assays demonstrated that the migration and invasive rates of the cells isolated from both patients decreased along disease progression. Conversely, in both patients, cells representing late-stage disease demonstrated a higher adhesion capacity to the 3D organotypic model than those representing an early-stage disease. This adhesive behavior is associated with the in vivo tumor capacity of the cells. Regardless of these differences in adhesive, migratory, and invasive behavior among the experimental protocols used, cytostatic doses of mifepristone were able to inhibit the adhesion, migration, and invasion rates of all cells studied, regardless of their basal capabilities over simplistic or organotypic metastatic in vitro model systems. Finally, we demonstrate that when cells acquire the capacity to grow spontaneously as spheroids, they do attach to a 3D organotypic model system when pre-incubated with conditioned media. Of relevance, mifepristone was able to cause dissociation of these multicellular structures.

CONCLUSION

Differences in cellular behaviours were observed between 2 and 3D assays when studying the metastatic capabilities of high-grade serous ovarian cancer cells representing disease progression. Mifepristone inhibited these metastatic capabilities in all assays studied.

Mechanisms of Peritoneal Mesothelial Cells in Peritoneal Adhesion

A peritoneal adhesion (PA) is a fibrotic tissue connecting the abdominal or visceral organs to the peritoneum. The formation of PAs can induce a variety of clinical diseases. However, there is currently no effective strategy for the prevention and treatment of PAs. Damage to peritoneal mesothelial cells (PMCs) is believed to cause PAs by promoting inflammation, fibrin deposition, and fibrosis formation. In the early stages of PA formation, PMCs undergo mesothelial–mesenchymal transition and have the ability to produce an extracellular matrix. The PMCs may transdifferentiate into myofibroblasts and accelerate the formation of PAs. Therefore, the aim of this review was to understand the mechanism of action of PMCs in PAs, and to offer a theoretical foundation for the treatment and prevention of PAs.

Activating SIRT3 in peritoneal mesothelial cells alleviates postsurgical peritoneal adhesion formation by decreasing oxidative stress and inhibiting the NLRP3 inflammasome

Peritoneal adhesions (PAs) are a serious complication of abdominal surgery and negatively affect the quality of life of millions of people worldwide. However, a clear molecular mechanism and a standard therapeutic strategy for PAs have not been established. Here, we developed a standardized method to mimic the pathological changes in PAs and found that sirtuin 3 (SIRT3) expression was severely decreased in adhesion tissues, which was consistent with our bioinformatics analysis and patient adhesion tissue analysis. Thus, we hypothesized that activating SIRT3 could alleviate postsurgical PAs. Sirt3-deficient (Sirt3^−/−) mice exhibited many more PAs after standardized abdominal surgery. Furthermore, compared with wild-type (Sirt3^+/+) mice, Sirt3-deficient (Sirt3^−/−) mice showed more prominent reactive oxygen species (ROS) accumulation, increased levels of inflammatory factors, and exacerbated mitochondrial damage and fragmentation. In addition, we observed NLRP3 inflammasome activation in the adhesion tissues of Sirt3^−/− but, not Sirt3^+/+ mice. Furthermore, mesothelial cells sorted from Sirt3^−/− mice exhibited impaired mitochondrial bioenergetics and redox homeostasis. Honokiol (HKL), a natural compound found in several species of the genus Magnolia, could activate SIRT3 in vitro. Then, we demonstrated that treatment with HKL could reduce oxidative stress and the levels of inflammatory factors and suppress NLRP3 activation in vivo, reducing the occurrence of postsurgical PAs. In vitro treatment with HKL also restored mitochondrial bioenergetics and promoted mesothelial cell viability under oxidative stress conditions. Taken together, our findings show that the rescue of SIRT3 by HKL may be a new therapeutic strategy to alleviate and block postsurgical PA formation.

Treatment with honokiol, a compound found in magnolia tree bark, significantly reduces formation of internal scar tissue after abdominal surgery in mice. Healing of incisions in the peritoneum, the connective tissue lining the abdomen, can result in scar tissue bonds known as peritoneal adhesions (PA), causing complications such as infertility or bowel obstructions. The mechanism of PA formation is unknown, and no therapies are available. Xuqi Li at The First Affiliated Hospital of Xi’an Jiaotong University, China, and co-workers found that PA tissues in both mice and human patients had decreased levels of SIRT3, a stress-response protein. Mice lacking SIRT3 showed increased inflammation and PA formation. When mice were treated with honokiol the day after surgery in order to boost SIRT3 levels, PA formation was significantly decreased. These results suggest a possible preventative treatment for post-surgical PAs.

Altered intraperitoneal immune microenvironment in patients with peritoneal metastases from gastric cancer

Background

The peritoneal cavity contains many site-specific immune cells which constitute a unique immune microenvironment. However, it is unclear how the local immune signature is altered in patients with peritoneal metastases (PM).

Methods

Peritoneal lavage fluid or ascites were obtained from 122 patients with various stages of gastric cancer (GC). Cells recovered from peritoneal fluids were immunostained with mAbs for lymphocyte-, macrophage- and tumor cell-specific antigens and the frequencies of leukocyte subsets and antigen expression levels were evaluated with multi-color flowcytometry.

Results

The proportions of CD8(+) T cells, CD3(+)CD56(+) NKT-like cells, and CD3(-)CD56(+) NK cells to CD45(+) leukocytes were significantly reduced in patients with PM compared to those without PM. In patients with PM, the rates of CD8 (+) T cells and NKT-like cells correlated inversely with the tumor leukocyte ratio (TLR), the relative frequency of CD326(+) tumor cells to CD45(+) leukocytes. In contrast, the proportion of CD19(+) B cells was significantly increased in patients with PM, and their proportion correlated positively with the TLR and peritoneal carcinomatosis index (PCI) score. In patients with PM, CD14(+) macrophages tended to be increased with enhanced expression of CD14, CD16 and a M2-macrophage marker, CD163. In particular, macrophages in patients with high TLR contained many granules with high side scatter and CD14 expression in their flow profile compared to those without PM.

Conclusion

PM are accompanied by a drastic change in phenotypes of lymphocyte and macrophage in the peritoneal cavity, which might be involved in the development and progression of intraperitoneal tumor growth.

Innate immune response to peritoneal bacterial infection

Spontaneous and secondary peritoneal infections, mostly of bacterial origin, easily spread to cause severe sepsis. Cellular and humoral elements of the innate immune system are constitutively present in peritoneal cavity and omentum, and play an important role in peritonitis progression and resolution. This review will focus on the description of the anatomic characteristics of the peritoneal cavity and the composition and function of such innate immune elements under both steady-state and bacterial infection conditions. Potential innate immune-based therapeutic interventions in bacterial peritonitis alternative or adjunctive to classical antibiotic therapy will be briefly discussed.

Investigating the mechanisms of peritoneal metastasis in gastric adenocarcinoma using a novel ex vivo peritoneal explant model

Gastric adenocarcinoma, commonly known as stomach cancer, has a predilection for metastasis to the peritoneum, which portends limited survival. The peritoneal metastatic cascade remains poorly understood, and existing models fail to recapitulate key elements of the interaction between cancer cells and the peritoneal layer. To explore the underlying cellular and molecular mechanisms of peritoneal metastasis, we developed an ex vivo human peritoneal explant model. Fresh peritoneal tissue samples were suspended, mesothelial layer down but without direct contact, above a monolayer of red-fluorescent dye stained AGS human gastric adenocarcinoma cells for 24 h, then washed thoroughly. Implantation of AGS cells within the explanted peritoneum and invasion beyond the mesothelial layer were examined serially using real-time confocal fluorescence microscopy. Histoarchitecture of the explanted peritoneum was preserved over 5 days ex vivo. Both implantation and invasion were suppressed by restoration of functional E-cadherin through stable transfection of AGS cells, demonstrating sensitivity of the model to molecular manipulation. Thus, our ex vivo human peritoneal explant model permits meaningful investigation of the pathways and mechanism that contribute to peritoneal metastasis. The model will facilitate screening of new therapies that target peritoneal dissemination of gastric, ovarian and colorectal cancer.

Proteomic study of mesothelial and endothelial cross-talk: key lessons

INTRODUCTION

The peritoneum, pleura, and pericardium are yet understudied multicellular systems where mesothelial cells (MCs) and endothelial cells (ECs) are in close proximity. Crosstalk between these cell types likely plays role in molecular transport, immunological reactions, and metabolic processes in health, disease, and therapeutic intervention.

AREAS COVERED

In this review, we discuss recent proteomic efforts to characterize the crosstalk between MC and EC. We describe the proteomic methods necessary for investigation of crosstalk between MC and EC, as well as the in-vitro models that can be employed. Potential experimental approaches range from conditioned medium, via co-culture on semi-permeable membranes, to 3D cell culture based organoid models. While the biological and clinical relevance of the models may increase with their ability to mimic close cell communication, the practicality of these complex experiments corresponds vice versa, making standardization more difficult and expensive.

EXPERT OPINION

Currently, data and reports on mesothelial-to-endothelial crosstalk are still very scarce. In our opinion, the in-vitro model using semi-permeable cell culture inserts will allow to establish a basic understanding of cellular crosstalk that may occur between those cell types. Later-on, more sophisticated 3D cell cultures may be better able to simulate the transport dynamics within the peritoneal membrane.

The role of dendritic cells in the immune niche of the peritoneum

Dendritic cells (DCs) are professional antigen presenting cells that play an important role in the induction of T cell responses. Different subsets (cDC1s, cDC2s, pDCs, and moDCs) were described based on the expression of different surface markers and functions. In the context of peritoneum, DCs are also a key population cell orchestrating immune responses against pathogens, malignant cells and tissue-damage. Furthermore, they play an important role in the promotion of an anti-inflammatory microenvironment, which is necessary to maintain tolerance and adipocyte homeostasis. The aim of this review is to summarize the current knowledge of the functional and phenotypic features of peritoneal DCs and shed some light on the importance of these cells within this unique cavity and its associated components: the omentum, the mesentery and gut-associated lymphoid tissue (GALT).

Role of Peritoneal Mesothelial Cells in the Progression of Peritoneal Metastases

Peritoneal metastatic cancer comprises a heterogeneous group of primary tumors that originate in the peritoneal cavity or metastasize into the peritoneal cavity from a different origin. Metastasis is a characteristic of end-stage disease, often indicative of a poor prognosis with limited treatment options. Peritoneal mesothelial cells (PMCs) are a thin layer of cells present on the surface of the peritoneum. They display differentiated characteristics in embryonic development and adults, representing the first cell layer encountering peritoneal tumors to affect their progression. PMCs have been traditionally considered a barrier to the intraperitoneal implantation and metastasis of tumors; however, recent studies indicate that PMCs can either inhibit or actively promote tumor progression through distinct mechanisms. This article presents a review of the role of PMCs in the progression of peritoneum implanted tumors, offering new ideas for therapeutic targets and related research.

A Comparative Study Between Porcine Peritoneum and Pericardium as Cardiovascular Material

Decellularized porcine pericardium has many applications in the cardiovascular field for its excellent properties. The peritoneum is a single-layer bio-dialysis membrane with many similarities and differences in physical characteristics, biochemical composition, and structure to the pericardium. The limited available literature suggests that, similar to the pericardium, the peritoneum has good application potential in the field of cardiovascular substitute materials. This research focused on comparing the differences between decellularized peritoneum and decellularized pericardium in microstructure, biochemical composition, mechanical properties, hemocompatibility, in vitro enzymatic degradation, in vitro calcification, cytocompatibility, and other vital indicators. The peritoneum was consistent with pericardium in terms of fibrous structure, hemocompatibility, in vitro calcification, and cytocompatibility. The peritoneal elastic fiber content (219 μg/mg) was significantly higher than that of the pericardium (66 μg/mg), resulting in two to three times higher maximum load (21.1 N) and burst pressure (1309 mmHg), and better performance than the pericardium in terms of in vitro resistance to enzymatic degradation. In the cardiovascular field, decellularized peritoneum can be used as vascular substitute material. Impact statement There are many similarities between the embryonic origin and morphological structure of the porcine peritoneum and the porcine pericardium, but little research has been done on the use of the porcine peritoneum as a biomaterial. In this compared research, we showed that porcine peritoneum had better resistance to enzymatic degradation, better stretching, and more suitable burst pressure for being used as vascular substitute material. This research is the first to describe the structural composition of porcine peritoneum and its advantageous properties as a cardiovascular material.

Molecular Mechanisms of Peritoneal Membrane Pathophysiology

The peritoneal membrane is the largest internal membrane of the human body, having a surface area that approximates the surface area of the skin [...]

Current Trends in Cytoreductive Surgery (CRS) and Hyperthermic Intraperitoneal Chemotherapy (HIPEC) for Peritoneal Disease from Appendiceal and Colorectal Malignancies

Peritoneal carcinomatosis (PC) is a poor prognostic factor for all malignancies. This extent of metastatic disease progression remains difficult to treat with systemic therapies due to poor peritoneal vascularization resulting in limited drug delivery and penetration into tissues. Cytoreductive surgery (CRS) and hyperthermic intraperitoneal chemotherapy (HIPEC) are surgical interventions that directly target peritoneal tumors and have improved outcomes for PC resulting from appendiceal and colorectal cancer (CRC). Despite these radical therapies, long-term survival remains infrequent, and recurrence is common. The reasons for these outcomes are multifactorial and signal the need for the continued development of novel therapeutics, techniques, and approaches to improve outcomes for these patients. Here, we review landmark historical studies that serve as the foundation for current recommendations, recent discoveries, clinical trials, active research, and areas of future interest in CRS/HIPEC to treat PC originating from appendiceal and colorectal malignancies.

Metastatic Voyage of Ovarian Cancer Cells in Ascites with the Assistance of Various Cellular Components

Epithelial ovarian cancer (EOC) is the most lethal gynecologic malignancy and has a unique metastatic route using ascites, known as the transcoelomic root. However, studies on ascites and contained cellular components have not yet been sufficiently clarified. In this review, we focus on the significance of accumulating ascites, contained EOC cells in the form of spheroids, and interaction with non-malignant host cells. To become resistant against anoikis, EOC cells form spheroids in ascites, where epithelial-to-mesenchymal transition stimulated by transforming growth factor-β can be a key pathway. As spheroids form, EOC cells are also gaining the ability to attach and invade the peritoneum to induce intraperitoneal metastasis, as well as resistance to conventional chemotherapy. Recently, accumulating evidence suggests that EOC spheroids in ascites are composed of not only cancer cells, but also non-malignant cells existing with higher abundance than EOC cells in ascites, including macrophages, mesothelial cells, and lymphocytes. Moreover, hetero-cellular spheroids are demonstrated to form more aggregated spheroids and have higher adhesion ability for the mesothelial layer. To improve the poor prognosis, we need to elucidate the mechanisms of spheroid formation and interactions with non-malignant cells in ascites that are a unique tumor microenvironment for EOC.

Glycoprotein 96 in Peritoneal Dialysis Effluent-Derived Extracellular Vesicles: A Tool for Evaluating Peritoneal Transport Properties and Inflammatory Status

Background

Extracellular vesicles (EVs) from peritoneal dialysis effluent (PDE), containing molecules such as proteins and microRNAs (miRNAs), may be potential biological markers to monitor peritoneal function or injury. Peritoneal inflammation is an important determinant of peritoneal solute transport rate (PSTR). Thus, the aim of this study is to determine whether the specific proteins capable of evaluating the PSTR could be found in PDE-EVs, and explore the underlying mechanism for the association between PSTR and peritoneal inflammation.

Methods

Sixty patients undergoing peritoneal dialysis (PD) were divided into two groups: high/high average transport (H/A) group (PET >0.65) and low/low average transport (L/A) group (PET <0.65). EVs derived from PDE (PDE-EVs) were isolated by ultracentrifugation. Proteomic analysis was performed to explore the differentially expressed proteins and identify the potential biomarkers in PDE-EVs from the two groups, and we focused on glycoprotein 96 (GP96) as it could be involved in the inflammatory process. The expression of GP96 in PDE-EVs and inflammatory cytokines was quantified by real-time PCR and enzyme-linked immunosorbent assay. The infiltration of macrophages and neutrophils into the peritoneum was detected using immunohistochemistry in a PD rat model.

Results

The expression of PDE-EVs-GP96 was significantly higher in the H/A group, and was positively correlated with the PSTR and the level of the inflammatory factor interleukin (IL)-6. GP96-enriched EVs enhanced the secretion of proinflammatory cytokines IL-1β, IL-6, tumor necrosis factor (TNF)-α, and IL-8 in macrophages, which was reversed by a pharmacological GP96-specific inhibitor (PU-WS13). The GP96 inhibitor also reduced local peritoneal inflammation by decreasing the infiltration of inflammatory cells and levels of proinflammatory cytokines (IL-6 and TNF-α) and chemokines (CCL2, CXCL1, and CXCL2) in a PD rat model.

Conclusions

PDE-EVs-GP96 is a new promising tool to evaluate the status of peritoneal inflammation and PSTR, and the mechanism may be related to affecting the inflammatory properties of macrophages.