Peritoneal Inflammation Research Articles

Impact of Peritoneal Neutrophil Extracellular Traps on Peritoneal Characteristics and Technical Failure in Patients Undergoing Peritoneal Dialysis.

Peritoneal dialysis (PD) is an effective home therapy for end-stage kidney disease. However, continuous exposure to PD fluids with high glucose concentration and recurrent peritonitis may lead to the activation of cellular and molecular processes of peritoneal damage, including inflammation and fibrosis. In particular, recent studies have highlighted the role of neutrophils in chronic inflammation. This study explores how neutrophil extracellular traps (NETs) affect peritoneal membrane function and contribute to technical failures in PD patients. We conducted a prospective observational study involving 250 non-infectious and 30 acute peritonitis patients. NETs were measured using nucleosome and myeloperoxidase DNA levels in PD fluids. Monocyte chemoattractant protein-1 (MCP-1) and matrix metalloproteinase-8 (MMP-8) were also measured to assess peritoneal inflammation and damage. A significant increase in peritoneal NETs, as determined by nucleosome and myeloperoxidase DNA levels, was observed in patients with acute peritonitis compared to patients without peritonitis. Even in non-infectious samples, NET levels were widely distributed and closely correlated with levels of MCP-1 and MMP-8. Higher levels of peritoneal NETs were closely associated with increased 4-hour dialysate/peritoneal (D/P) creatinine ratio and 1-hour D/P sodium levels, indicating a higher prevalence of fast transport and limited free water transport. These factors were associated with a higher risk of technical failure. During a mean follow-up of 34 months, 39.2% (98 patients) switched from PD to hemodialysis, with higher NET levels significantly increasing the risk by 1.9 times (95% confidence interval 1.27-2.83, p=0.020). This study suggests the importance of peritoneal NETs not only as markers of acute inflammation but also as significant immunological predictors of chronic peritoneal membrane inflammation and dysfunction, and as potential risk factors for technical failure.

The multiple roles of macrophages in peritoneal adhesion

AbstractPeritoneal adhesion (PA) refers to the abnormal adhesion of the peritoneum either with the peritoneum itself or with tissues and organs that is caused by abdominopelvic surgery, abdominal infection or peritoneal inflammation. PA is associated with various clinical complications, such as abdominal pain and distension, intestinal obstruction, gastrointestinal disorders and female infertility, and adversely affects the quality of life of patients. Macrophages are essential for PA formation and can undergo polarization into classically activated macrophages (M1) and alternatively activated macrophages (M2), which are influenced by the peritoneal microenvironment. By releasing proinflammatory cytokines and reactive oxygen species, M1 macrophages promote peritoneal inflammatory reactions and the resultant formation of adhesion. In contrast, M2 macrophages secrete anti‐inflammatory cytokines and growth factors to inhibit PA formation and to promote repair and healing of peritoneal tissues, and thereby play a significant anti‐inflammatory role. This review comprehensively explores the function and mechanism of macrophages and their subtypes in PA formation to gain insight into the prevention and treatment of PA based on the modulation of macrophages.

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.

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

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

Antinociceptive and antineuropathic effects of Trifolium resupinatum L. on formalin-induced nociception and cervical spinal cord hemi-contusion: Underlying Mechanisms

Ethnopharmacological relevanceTrifolium resupinatum L. (Fabaceae), known as Persian clover, ethnomedicinally used in Persian folk medicine to treat peritoneal inflammation, rheumatism, and back pain. Aim of the studyTo investigate the antineuropathic and antinociceptive activities of Trifolium resupinatum leaves essential oil (TREO) in male Wistar rats, as well as to explore the potential mechanisms of action. Materials and methodsThe antinociceptive activity of TREO and its main constituents, quercetin (Qc) was assessed using the formalin-induced paw licking test. Moreover, the potential mechanisms of antinociception were evaluated through various competitive and non-competitive antagonisms. Additionally, the antineuropathic potential was investigated using the cervical spinal cord hemi-contusion (CCS) model, and the role of phosphorylated Stat-3 was analyzed using Western blotting. ResultsTREO exerted significant antinociceptive activity (P < 0.01) in both phases of the formalin-induced test; however, its effects were more pronounced in the second phase. Modulators of the NO-cGMP-K+ channel pathway significantly reversed the antinociceptive activity of TREO (P < 0.05). Additionally, antagonists of TRPV1 and TRPV2, as well as CB1 and GABAA receptors, significantly reversed the antinociceptive effects of TREO (P < 0.05). In another study, both TREO and Qc significantly attenuated hyperalgesia and mechanical allodynia (P < 0.01) when evaluated using the CCS-induced nociception model. Notably, TREO also reduced the expression levels of interleukin-1 beta, interleukin-2, and tumor necrosis factor alpha in CCS-induced rats (P < 0.05). ConclusionTREO and Qc exhibit both antinociceptive and anti-neuropathic activities. The antinociceptive effects are partially mediated through the NO-cGMP-K+ channel pathways, along with the activation of TRPV, GABA, and cannabinoid receptors. Furthermore, the anti-neuropathic activity of TREO may be partially regulated through the inhibition of cytokines.

6688 Clinical Presentation and Management of Highly Differentiated Follicular Carcinoma Arising from Struma Ovarii with DICER1 Mutation: A Case Report

Abstract Disclosure: S.M. Seav: None. J. Shah: None. C. Dosiou: None. Background: Struma ovarii (SO) is a rare type of ovarian teratoma comprised of &amp;gt; 50% thyroid tissue. Extra-ovarian spread of SO, called peritoneal strumosis, was previously considered benign given the lack of histological malignant features. The 2020 WHO Classification of Female Genital Tumors has reclassified this as highly differentiated follicular carcinoma arising from struma ovarii (HDFCO), highlighting its low-grade malignant potential.[1] We report a case of HDFCO with extensive peritoneal disease and discuss its management. Clinical Case: A 38-year-old female presented to her OBGYN for irregular menses. Pelvic MRI showed an 8 cm right ovarian mass. Right salpingo-oopherectomy and pelvic peritoneal biopsies revealed well-differentiated thyroid tissue. Thyroid ultrasound demonstrated a multinodular goiter with ATA high risk nodules; 4 of 5 biopsied with benign results. Her thyroglobulin (Tg) was 170 ng/mL (normal 2 – 35 ng/ml). No further intervention was recommended. Two years later she was referred to our clinic. CT of abdomen/pelvis showed multifocal residual disease. We recommended more aggressive management, given the diagnosis of HDFCO. All visible disease was resected in a diagnostic laparoscopy with pelvic and omental biopsies. Pathology showed well-differentiated thyroid tissue. Molecular testing for the FGFR4 mutation associated with HDFCO was negative, but there was a DICER1 mutation c.5428 G&amp;gt;T of undetermined significance. DICER1 mutations are associated with thyroid cancers2. A total thyroidectomy and radioactive iodine ablation (RAI) were recommended. Thyroid pathology was benign. Tg was 9 ng/mL one month post-op. MRI six months post-laparoscopy revealed only one 6 mm omental lesion. Withdrawal I-123 whole body scan (WBS) showed multiple peritoneal implants. Tg was 214 ng/mL and TSH was 72 ulU/mL. The patient was treated with 157 mCi of oral I-131. Given the extensive peritoneal disease, she received prophylactic oral dexamethasone for 2 weeks after RAI to decrease the risk of peritoneal inflammation and bowel obstruction potentially mediated by local inflammation from radiation-related tissue injury. Her Tg three months post-RAI was 4 ng/mL. The surveillance plan is to alternate between RAI WBS and MRI abdomen/pelvis every 6 months. Conclusions: Peritoneal strumosis, previously considered benign, has recently been reclassified as HFDCO, an extremely rare low-grade malignancy with no standardized treatment. We report the first case of extensive HFDCO with a DICER1 mutation. Given the significant peritoneal involvement, our case was treated with total thyroidectomy, surgical excision of all implants, RAI, and prophylactic steroids post-RAI. Further research into the prognostic factors and optimal treatment of HFDCO is needed. Reference: [1]Giovanopoulou et al. Curr Oncol. 2022; 29(12): 9105-9116. 2Sauer et al. Head Neck Pathol. 2022; 16(1): 190–199. Presentation: 6/1/2024

Glucose-Free Solutions Mediated Inhibition of Oxidative Stress and Oxidative Stress-Related Damages in Peritoneal Dialysis: A Promising Solution.

Oxidative stress (OxSt) and inflammation are common in end-stage renal disease and dialysis patients; they are known risk factors for cardiovascular disease and mortality. In peritoneal dialysis (PD), OxSt and inflammation are even further increased compared to the already increased oxidative stress of their pre-dialysis phase. This is due to the high glucose-based solutions currently used, whose continuous contact with the peritoneal membrane can induce significant long-term morphological and functional changes (mesothelial to mesenchymal transition, thickening, neo-angiogenesis and fibrosis) of the peritoneal membrane. Oxidative stress plays a very important role in these processes, which may compromise the peritoneal dialysis procedure. There is, therefore, the need for more biocompatible dialysis fluids with polymers other than glucose to prevent and treat OxSt and inflammation. The most known and used of such glucose-free and more biocompatible peritoneal dialysis solutions is icodextrin, which has shown a protective effect from oxidative stress. This has supported the consideration of the use of glucose-free-based peritoneal dialysis fluids in order to reduce oxidative stress and improve peritoneal membrane survival. Studies investigating peritoneal dialysis with the use of osmo-metabolic agents (L-carnitine, xylitol and their combination) in peritoneal fluids replacing glucose-based fluids are, in fact, ongoing. They represent a promising strategy to reduce OxSt, preserve the peritoneal membrane's integrity and improve patients' outcome.

Deletion of p38 MAPK in macrophages ameliorates peritoneal fibrosis and inflammation in peritoneal dialysis

One of the most common causes of peritoneal dialysis withdrawal is ultrafiltration failure which is characterized by peritoneal membrane thickening and fibrosis. Although previous studies have demonstrated the inhibitory effect of p38 MAPK inhibitors on peritoneal fibrosis in mice, it was unclear which specific cells contribute to peritoneal fibrosis. To investigate the role of p38 MAPK in peritoneal fibrosis more precisely, we examined the expression of p38 MAPK in human peritoneum and generated systemic inducible p38 MAPK knockout mice and macrophage-specific p38 MAPK knockout mice. Furthermore, the response to lipopolysaccharide (LPS) was assessed in p38 MAPK-knocked down RAW 264.7 cells to further explore the role of p38 MAPK in macrophages. We found that phosphorylated p38 MAPK levels were increased in the thickened peritoneum of both human and mice. Both chlorhexidine gluconate (CG)-treated systemic inducible and macrophage-specific p38 MAPK knockout mice ameliorated peritoneal thickening, mRNA expression related to inflammation and fibrosis, and the number of αSMA- and MAC-2-positive cells in the peritoneum compared to CG control mice. Reduction of p38 MAPK in RAW 264.7 cells suppressed inflammatory mRNA expression induced by LPS. These findings suggest that p38 MAPK in macrophages plays a critical role in peritoneal inflammation and thickening.

Exercise-stimulated Resolvin Biosynthesis in Adipose Tissue is Abrogated by High Fat Diet-induced Adrenergic Deficiency.

Diet-induced white adipose tissue inflammation is associated with insulin resistance and metabolic perturbations. Conversely, exercise (Exe) protects against the development of chronic inflammation and insulin resistance independent of changes in weight; however, the mechanisms remain largely unknown. We have recently shown that, through adrenergic stimulation of macrophages, exercise promotes resolution of acute peritoneal inflammation by enhancing the biosynthesis of specialized pro-resolving lipid mediators (SPMs). In this study, we sought to determine if exercise stimulates pro-resolving pathways in adipose tissue and whether this response is modified by diet. Specifically, we hypothesized that high fat diet feeding disrupts exercise-stimulated resolution by inhibiting adrenergic signaling, priming the development of chronic inflammation in adipose tissue (AT). To explore the dietary dependence of the pro-resolving effects of Exe, mice were fed either a control or high-fat diet (HFD) for 2 weeks prior to, and throughout, a 4 wk period of daily treadmill running. Glucose handling, body weight and composition, and exercise performance were evaluated at the end of the feeding and exercise interventions. Likewise, catecholamines and their biosynthetic enzymes were measured along with AT SPM biosynthesis and macrophage phenotype and abundance. When compared with sedentary controls (Sed), macrophages isolated from mice exposed to 4 wk of exercise display elevated expression of the SPM biosynthetic enzyme Alox15, while whole AT SPM levels and anti-inflammatory CD301+ M2 macrophages increased. These changes were dependent upon diet as 6 wk of feeding with HFD abrogated the pro-resolving effect of exercise when compared with control diet-fed animals. Interestingly, exercise-induced epinephrine production was inhibited by HFD, which diminished expression of the epinephrine biosynthetic enzyme phenylethanolamine N-methyltransferase (PNMT) in adrenal glands. Taken together, these results suggest that a diet high in fat diminishes the pro-resolving effects of exercise in adipose tissue via decreasing the biosynthesis of catecholamines.

Pathophysiological Mechanisms of Peritoneal Fibrosis and Peritoneal Membrane Dysfunction in Peritoneal Dialysis.

The characteristic feature of chronic peritoneal damage in peritoneal dialysis (PD) is a decline in ultrafiltration capacity associated with pathological fibrosis and angiogenesis. The pathogenesis of peritoneal fibrosis is attributed to bioincompatible factors of PD fluid and peritonitis. Uremia is associated with peritoneal membrane inflammation that affects fibrosis, neoangiogenesis, and baseline peritoneal membrane function. Net ultrafiltration volume is affected by capillary surface area, vasculopathy, peritoneal fibrosis, and lymphangiogenesis. Many inflammatory cytokines induce fibrogenic growth factors, with crosstalk between macrophages and fibroblasts. Transforming growth factor (TGF)-β and vascular endothelial growth factor (VEGF)-A are the key mediators of fibrosis and angiogenesis, respectively. Bioincompatible factors of PD fluid upregulate TGF-β expression by mesothelial cells that contributes to the development of fibrosis. Angiogenesis and lymphangiogenesis can progress during fibrosis via TGF-β-VEGF-A/C pathways. Complement activation occurs in fungal peritonitis and progresses insidiously during PD. Analyses of the human peritoneal membrane have clarified the mechanisms by which encapsulating peritoneal sclerosis develops. Different effects of dialysates on the peritoneal membrane were also recognized, particularly in terms of vascular damage. Understanding the pathophysiologies of the peritoneal membrane will lead to preservation of peritoneal membrane function and improvements in technical survival, mortality, and quality of life for PD patients.

Pressure induces peritoneal fibrosis and inflammation through CD44 signaling

Peritoneal dialysis (PD) is a widely used sustainable kidney replacement therapy. Prolonged use of PD fluids is associated with mesothelial-mesenchymal transition, peritoneal fibrosis, and eventual ultrafiltration (UF) failure. However, the impact of pressure on the peritoneum remains unclear. In the present study, we hypothesized increased pressure is a potential contributing factor to peritoneal fibrosis and investigated the possible mechanisms. In vitro experiments found that pressurization led to a mesenchymal phenotype, the expression of fibrotic markers and inflammatory factors in human mesothelial MeT-5A cells. Pressure also increased cell proliferation and augmented cell migration potential in MeT-5A cells. The mouse PD model and human peritoneum equilibrium test (PET) data both showed a positive association between higher pressure and increased small solute transport, along with decreased net UF. Mechanistically, we found that significant upregulation of CD44 in mesothelial cells upon pressurization. Notably, the treatment of CD44 neutralizing antibodies prevented pressure-induced phenotypic changes in mesothelial cells, while a CD44 inhibitor oligo-fucoidan ameliorated pressure-induced peritoneal thickening, fibrosis, and inflammation in PD mice. To conclude, intraperitoneal pressure results in peritoneal fibrosis in PD via CD44-mediated mesothelial changes and inflammation. CD44 blockage can be utilized as a novel preventive approach for PD-related peritoneal fibrosis and UF failure.

Protective effect of Cyclo(His-Pro) on peritoneal fibrosis through regulation of HDAC3 expression.

Peritoneal dialysis is a common treatment for end-stage renal disease, but complications often force its discontinuation. Preventive treatments for peritoneal inflammation and fibrosis are currently lacking. Cyclo(His-Pro) (CHP), a naturally occurring cyclic dipeptide, has demonstrated protective effects in various fibrotic diseases, yet its potential role in peritoneal fibrosis (PF) remains uncertain. In a mouse model of induced PF, CHP was administered, and quantitative proteomic analysis using liquid chromatography-tandem mass spectrometry was employed to identify PF-related protein signaling pathways. The results were further validated using human primary cultured mesothelial cells. This analysis revealed the involvement of histone deacetylase 3 (HDAC3) in the PF signaling pathway. CHP administration effectively mitigated PF in both peritoneal tissue and human primary cultured mesothelial cells, concurrently regulating fibrosis-related markers and HDAC3 expression. Moreover, CHP enhanced the expression of nuclear factor erythroid 2-related factor 2 (Nrf2) while suppressing forkhead box protein M1 (FOXM1), known to inhibit Nrf2 transcription through its interaction with HDAC3. CHP also displayed an impact on spleen myeloid-derived suppressor cells, suggesting an immunomodulatory effect. Notably, CHP improved mitochondrial function in peritoneal tissue, resulting in increased mitochondrial membrane potential and adenosine triphosphate production. This study suggests that CHP can significantly prevent PF in peritoneal dialysis patients by modulating HDAC3 expression and associated signaling pathways, reducing fibrosis and inflammation markers, and improving mitochondrial function.

Cholinergic macrophages promote the resolution of peritoneal inflammation

The non-neural cholinergic system plays a critical role in regulating immune equilibrium and tissue homeostasis. While the expression of choline acetyltransferase (ChAT), the enzyme catalyzing acetylcholine biosynthesis, has been well documented in lymphocytes, its role in the myeloid compartment is less understood. Here, we identify a significant population of macrophages (Mϕs) expressing ChAT and synthesizing acetylcholine in the resolution phase of acute peritonitis. Using Chat-GFP reporter mice, we observed marked upregulation of ChAT in monocyte-derived small peritoneal Mϕs (SmPMs) in response to Toll-like receptor agonists and bacterial infections. These SmPMs, phenotypically and transcriptionally distinct from tissue-resident large peritoneal macrophages, up-regulated ChAT expression through a MyD88-dependent pathway involving MAPK signaling. Notably, this process was attenuated by the TRIF-dependent TLR signaling pathway, and our tests with a range of neurotransmitters and cytokines failed to induce a similar response. Functionally, Chat deficiency in Mϕs led to significantly decreased peritoneal acetylcholine levels, reduced efferocytosis of apoptotic neutrophils, and a delayed resolution of peritonitis, which were reversible with exogenous ACh supplementation. Intriguingly, despite B lymphocytes being a notable ChAT-expressing population within the peritoneal cavity, Chat deletion in B cells did not significantly alter the resolution process. Collectively, these findings underscore the crucial role of Mϕ-derived acetylcholine in the resolution of inflammation and highlight the importance of the non-neuronal cholinergic system in immune regulation.

Oxidative stress reduction by icodextrin-based glucose-free solutions in peritoneal dialysis: Support for new promising approaches.

Oxidative stress (OxSt) and inflammation are common in CKD and are known CV and mortality risk factors. In peritoneal dialysis (PD) OxSt and Inflammation even increase due to the use of glucose-based solutions. This study analyzed in 15 PD patients the effect of 3 and 6 months of treatment with icodextrin-based glucose-free solutions on OxSt and inflammation, evaluating p22phox protein expression (Western blot), NADPH oxidase subunit, essential for OxSt activation, MYPT-1 phosphorylation state, marker of RhoA/Rho kinase pathway (ROCK) activity, involved in the induction of OxSt (Western blot) and Malondialdehyde (MDA) production (fluorimetric assay). Interleukin (IL)-6 blood level (chemiluminescence assay) has been measured and used as a marker of inflammation. p22phox protein expression, MYPT 1 phosphorylation, and MDA were reduced after 3 months from the start of icodextrin (1.28 ± 0.18 d.u. vs. 1.50 ± 0.19, p = 0.049; 0.89 ± 0.03 vs. 0.98 ± 0.03, p = 0.004; 4.20 ± 0.18 nmol/mL vs. 4.84 ± 0.32 nmol/mL, p = 0.045, respectively). In a subgroup of 9 patients who continued the treatment up to 6 months, MYPT-1 phosphorylation was further reduced at 6 months compared to baseline (0.84 ± 0.06 vs. 0.99 ± 0.04, p = 0.043), while p22phox protein expression was reduced only at 6 months versus baseline (1.03 ± 0.05 vs. 1.68 ± 0.22, p = 0.021). In this subgroup, MDA was reduced at 6 months versus baseline (4.03 ± 0.24 nmol/mL vs. 4.68 ± 0,32, p = 0.024) and also versus 3 months (4.03 ± 0.24 vs. 4.35 ± 0.21, p = 0.008). IL-6 level although reduced both at 3 and 6 months, did not reach statistical significance. The reduction of OxSt with icodextrin-based PD solutions, although obtained in a small patients cohort and in a limited time duration study, strongly supports the rationale of using osmo-metabolic agents-based fluids replacing glucose-based fluids. Ongoing studies with these agents will provide information regarding preservation of peritoneal membrane integrity, residual renal function, and reduction of CVD risk factors such as OxSt and inflammation.

#1980 Past peritonitis episodes are linked to decreased peritoneal Immune Cell Function and Associated with Chronic Increased Peritoneal Inflammation

Abstract Background and Aims Chronic peritoneal inflammation and infectious complications occur in a significant proportion of PD patients. A relationship between peritoneal IL-6 levels and local immunocompetence is suspected. To analyse local immunocompetence, an ex-vivo stimulation assay of PD effluent was developed. The aim of this study was to analyse peritoneal inflammation and immunocompetence in a PD cohort in relation to clinical outcomes. Method Prospectively, 245 routinely performed 4-hour PETs (143 patients, 2679 patient-months) of patients exclusively receiving 2. generation PD fluids (two-chamber, pH neutral, low amount of glucose degradation products) were analysed. An ex-vivo cell stimulation protocol of the fresh effluents was performed of all PETs. Peritoneal immune cell function was analysed using ex-vivo Toll-like receptor (LPS/Pam3Cys) stimulated IL-6 release as an index of immunocompetence. The molecular effects of effluent components and the addition of alanyl-glutamine to PD fluid were analysed in heterologous cell stimulation experiments and using an effluent proteomics and metabolomics approach. Results IL-6 in the effluent showed no association with various patient characteristics (incl. RRF, underlying disease, peritonitis episodes, time on PD). A significant association of peritoneal IL-6 with solute transport rates and systemic markers of uremic inflammation was found. IL-6 in effluent (HR 2.54) and stimulated 1 h effluent (HR 0.34) was predictive of subsequent peritonitis episodes. An inverse association was observed with ex-vivo stimulated IL-6 release from peritoneal cells (P = .02), most pronounced in patients with a history of peritonitis (P = .008). Patients with above median elevated IL-6 levels showed reduced peritoneal immune cell function. The results were validated in an independent multi-centre PD cohort (n = 48). A proteomics (n = 17) and targeted metabolomics (patients n = 134, 1004 metabolites) analysis of PD effluents show an overrepresentation of apoptosis and neutrophil degranulation pathways in patients with elevated effluent IL-6 levels and reduced response mechanisms to pathogens when compared to effluents from patients with low effluent IL-6 levels. Heterologous donor-PBMC stimulation (4 Healthy donors) with 4h PET PD-effluents of 20 patients showed reduced immunocompetence with elevated IL-6 (P = .038) and improved immunocompetence when 8 mM alanyl-glutamine were added to the PD fluid during the dwell. These results could also be validated in a post-hoc analysis of a RCT testing alanyl-glutamine addition to PD fluid for 8 weeks in PD patients. Conclusion This is the first longitudinal study to show the relationship between peritoneal inflammation and impaired immune function of peritoneal cells, possibly predisposing to infectious complications. The possible underlying mechanistic link may represent the biological correlate (“immune-paralysis”) for PD patients at increased risk for recurrent episodes of peritonitis.

#2881 Glucose free-based solutions reduce oxidative stress in peritoneal dialysis: support for a new promising approach

Abstract Background and Aims Oxidative stress (OxSt) and inflammation are common in CKD which are known CV and mortality risk factors. In peritoneal dialysis (PD) OxSt and Inflammation even increase due to the use of glucose-based solutions. This study evaluated in PD patients the effect of 3 and 6 months treatment with icodextrin-based glucose-free solutions on OxSt and inflammation. Method In 15 PD patients using a molecular biology approach, p22phox protein expression (Western blot), subunit of NADPH oxidase, essential for OxSt activation, MYPT-1 phosphorylation state, marker of RhoA/Rho kinase pathway activity, deeply involved in OxSt generation (Western blot) and Malondialdehyde (MDA) production (fluorimetric assay), marker of lipid peroxidation, have been evaluated. High-sensitive C Reactive Protein (hsCRP) (immunoturbidimetric assay) and interleukin (IL)-6 (chemiluminescence assay), have been used as marker of inflammation. Results p22phox protein expression, MYPT-1 phosphorylation, and MDA level were reduced after 3 months from the start of icodextrin based solutions (1.28 ± 0.18 d.u. vs 1.50 ± 0.19, p = 0.049; 0.89 ± 0.03 vs 0.98 ± 0.03, p = 0.004; 4.20 ± 0.18 nmol/mL vs 4.84 ± 0.32 nmol/mL, p = 0.045, respectively). In a subgroup of 9 patients who continued the treatment up to 6 months MYPT-1 phosphorylation was further reduced at 6 months compared to baseline (0.84 ± 0.06 vs 0.99 ± 0.04, p = 0.043), while p22phox protein expression was reduced only at 6 months from baseline (1.03 ± 0.05 vs 1.68 ± 0.22, p = 0.021). In this subgroup MDA blood level was reduced at 6 months from baseline (4.03 ± 0.24 nmol/mL vs 4.68 ± 0.32, p = 0.024) and was also significantly reduced vs 3 months (4.03 ± 0.24 vs 4.35 ± 0.21, p = 0.008). IL-6 level, although reduced compared to baseline, did not reach statistical significance both at 3 and 6 months, while hsPCR was unchanged. Conclusion The icodextrin-based PD solutions mediated reduction of OxSt related proteins and inflammation we have provided, although obtained in a small cohort of patients and for a limited time duration, strongly support the rationale of using in PD osmo-metabolic agents-based solutions replacing the currently used glucose-based fluids. The results of ongoing studies with these agents in PD patients will provide definitive proofs to better preserve peritoneal membrane integrity and residual renal function but also to reduce CV risk factors such as OxSt and inflammation.

#897 Peritoneal inflammation in PD-related peritonitis induces systemic eryptosis: in vitro and in vivo assessments

Abstract Background and Aims Erythrocytes (RBCs) have a highly specialized and organized membrane structure and undergo programmed cell death, known as eryptosis ( = stress-induced RBC death mechanism). Triggers of eryptosis include oxidative stress, inflammation and several uremic toxins. Our preliminary data show a significant increase of eryptosis during peritoneal dialysis (PD) -associated peritonitis in PD patients. The aims of this study were: assessment of incrementation of eryptosis in PD patients with peritonitis, evaluation of the relationship between systemic eryptosis in peritonitis and specific peritonitis biomarkers in PD effluent (PDE), and confirmation of the induction of eryptosis by peritonitis in a vitro setting. Method We enrolled 34 PD patients in stable condition (without systemic inflammation nor PD-related peritonitis in the last 3 months), 31 PD patients with acute peritonitis, and 17 healthy subjects (CTR). For PD stable patients, blood samples for eryptosis evaluation were drawn during the regular outpatient. For PD patients with peritonitis, blood samples and PDE samples were collected at the time of peritonitis diagnosis. PDE samples were used for peritoneal White Blood Cell count (pWBC), peritoneal Neutrophil Gelatinase-associated Lipocalin (pNGAL) and peritoneal cytokines levels (IL-1β and IL-6) measurements. For in vitro study, healthy RBCs were exposed to plasma of 31 PD patients with peritonitis and plasma of CTR group for 2, 4 and 24 hours. Morphological markers of eryptosis (cell membrane scrambling, cell shrinkage) and eryptosis percentage (based on PS exposure at RBC surface and AnnexinV-binding) were evaluated by flow cytometric analyses in vivo and in vitro. Results Totally, 65 chronic PD patients were included in this study. 57% of patients were treated with continuous ambulatory PD (CAPD) and 43% with automated PD (APD). The median PD vintage was 38 months (IQR 3.6–124.9 months). Table 1 reports clinical data for our PD population (Table 1). The percentage of AnnexinV-binding RBCs was significantly higher in PD patients than in CTR (2.7%; IQR 1.6–3.9 vs CTR: 0.8; IQR 0.7–1.3 P &amp;lt; .05). Eryptosis levels did not differ significantly between PD pts with and without diabetes, with and without hypertension, with and without cardiovascular disease. Eryptosis showed no significant differences between patients treated by CAPD/APD, and with Kt/Vurea values ≤ 1.7 and &amp;gt; 1.7. Generally, RBCs of all 65 PD patients were dramatically deranged in their morphology. In particular, RBCs from PD patients with peritonitis were characterized by dramatically deranged morphology and increased median cell volume in comparison with PD stable patients (P &amp;lt; .001). The percentages of AnnexinV-binding RBCs were significantly increased in the PD-associated peritonitis group (9.6%; IQR 4.2–16.7 versus 2.7%; IQR 1.6–3.9) (P&amp;lt;.0001) (Fig. 1). The percentage of AnnexinV-binding RBCs was significantly higher in PD patients with peritonitis than in healthy CTR (P &amp;lt; .001). We confirmed these in vivo data by in vitro results: healthy RBCs incubated with plasma from PD patients with peritonitis demonstrated a significant increase of eryptosis compared to healthy RBCs exposed to plasma from control group at all times (Fig. 2). Furthermore, significant positive strong correlations were observed between eryptosis level and all analysed peritoneal biomarkers of peritonitis (Spearman's rho pWBC = 0.77, P&amp;lt;.001, Spearman's rho pNGAL = 0.64, P = .001, Spearman's rho IL-6 = 0.61, P = .003 and Spearman's rho IL-1β = 0.64, P = .001,) (Fig. 3). Conclusion We investigated a potential connection between systemic eryptosis and peritoneal biomarkers of peritonitis. In particular, we theorized that the eryptosis enhancement is directly connected with peritonitis, and, based on the results, we hypothesized that the peritoneal membrane injury could be related to eryptosis. Upregulation of inflammatory markers could explain the increased rate of systemic eryptosis during PD-related peritonitis. In particular, we corroborated this point with our observations about in vitro induction of eryptosis by plasma from PD patients on the first day of peritonitis.

Tense Ascites in a Young Man Aged 24 Years Due to TB Peritonitis: Case Report

Tuberculous peritonitis is parietal or visceral peritoneal inflammation caused by Mycobacterium tuberculosis bacteria. Pathogenesis Tuberculous peritonitis is preceded by M. tuberculosis infection followed by spread to the peritoneum. This is a report from a young male patient with the main complaint of an increasingly enlarged stomach in 2 weeks and weight loss accompanied by other symptoms such as fever, nausea, vomiting, difficulty breathing. Investigation showed anemia, the results of Adenosine deaminase (ADA) ascitic fluid: 36.3 U/L. Radiological examination. Thorax photo showed Sinistra pleural effusion. Abdominal ultrasound found ascites. Then an ascitic puncture of approximately 2600 cc of greenish fluid was carried out. The diagnosis of tuberculous peritonitis is based on the Adenosine deaminase (ADA) test. Next, the patient received Fixed Drug Combination (FDC) therapy consisting of Rifampicin, Isoniazid, Pyrazinamide, and Ethambutol for 2 months, followed by a combination of Rifampicin and Isoniazid for 7-10 months. The prognosis of tuberculous peritonitis is fair if diagnosis is prompt and the patient is treated adequately.

Idiopathic Ascites after Laparoscopic Appendicectomy: a review of literature and a case report

Introduction: Minimal access surgery, encompassing laparoscopy and robotic procedures, has become the preferred choice for a wide range of surgical interventions, receiving widespread acceptance from both surgeons and patients. However, as the utilization of these minimally invasive techniques continues to grow, surgeons are increasingly confronted with unforeseen and puzzling complications. One such rare and perplexing complication is the emergence of ascites following laparoscopic procedures, particularly when no accidental injury to the bowel or urinary system has occurred, posing a challenging and distressing scenario for the operating surgeon. Aims and Objective:We have encountered a case of idiopathic ascites following a laparoscopic appendicectomy in a 10-year-old boy. The primary objective of this study is to conduct a comprehensive literature review to identify similar case reports and publications. By doing so, we aim to enhance our understanding of the causes and principles for managing idiopathic ascites occurring after laparoscopic surgery. Methods: A 10-year-old boy was admitted to the hospital with typical symptoms of acute appendicitis. Following evaluation, a nearly bloodless and uneventful laparoscopic appendicectomy was performed. However, postoperatively, he developed ascites accompanied by scrotal swelling due to scrotal edema, and despite thorough evaluation, no identifiable cause was found. The patient was managed conservatively and fully recovered without any subsequent complications. Results: The occurrence of ascites stemming from an idiopathic allergic or inflammatory peritoneal reaction during a laparoscopic procedure is exceptionally rare. During the patient's evaluation, the paramount concern was to rule out potentially significant complications such as bowel or urinary tract injuries, which can commonly result in postoperative peritoneal fluid accumulation. After the procedure, the boy underwent a thorough evaluation, but no definitive cause for the ascites was identified, further highlighting the enigmatic nature of this condition. Conclusion: Postoperative ascites without a discernible cause following laparoscopic surgery is an unexpected complication. In such cases, the leading hypothesis points to a peritoneal inflammatory reaction induced by agents utilized during laparoscopy. J Bangladesh Coll Phys Surg 2024; 42: 194-198

Marrubiin Inhibits Peritoneal Inflammatory Response Induced by Carrageenan Application in C57 Mice.

Marrubiin is a diterpene with a long history of a wide range of biological activities. In this study, the anti-inflammatory effects of marrubiin were investigated using several in vitro and in vivo assays. Marrubiin inhibited carrageenan-induced peritoneal inflammation by preventing inflammatory cell infiltration and peritoneal mast cell degranulation. The anti-inflammatory activity was further demonstrated by monitoring a set of biochemical parameters, showing that the peritoneal fluid of animals treated with marrubiin had lower levels of proteins and lower myeloperoxidase activity compared with the fluid of animals that were not treated. Marrubiin exerted the most pronounced cytotoxic activity towards peripheral mononuclear cells, being the main contributors to peritoneal inflammation. Additionally, a moderate lipoxygenase inhibition activity of marrubiin was observed.