In vivo efficacy of pyochelin-mediated delivery of zingerone in Pseudomonas aeruginosa-induced peritonitis.

Aim: The efficacy of a pyochelin-zingerone conjugate (PZC) against Pseudomonas aeruginosa in vivo in a mouse model of peritonitis, as well as mode of action in vitro, were investigated. Methods & results: Intraperitoneal administration of PZC (220 mg kg-1 b.wt.) resulted in a significant reduction in bacterial count in liver tissue by 2 log10 on the 4th day post infection. This was supported by reduced levels of inflammatory markers, liver function, inflammatory cytokines and improved histopathology. PZC showed its ability to disrupt the cellular membrane, increase permeability of the membrane and leakage of intracellular contents of P. aeruginosa, resulting in its death. Conclusion: The present study reports the hepatoprotective potential of PZC in an experimental model of P. aeruginosa-induced peritonitis.

Peritoneal Expression of Membrane Complement Regulators Is Decreased in Peritoneal Dialysis Patients with Infected Peritonitis.

In peritoneal dialysis (PD) patients, fungi and Pseudomonas aeruginosa are considered important causative microorganisms for peritonitis with poor prognosis. Our objective was to explore expressions of membrane complement (C) regulators (CRegs) and tissue injuries in the peritoneum of patients with PD-related peritonitis, including fungal and Pseudomonas aeruginosa peritonitis. In peritoneal biopsy tissues obtained at PD catheter removal, we investigated the severity of peritonitis-associated peritoneal injuries and the expression of CRegs, CD46, CD55, and CD59 against peritoneal tissues without any episode of peritonitis. In addition, we evaluated peritoneal injuries among fungal and Pseudomonas aeruginosa-peritonitis (P1) and Gram-positive bacterial peritonitis (P2). We also observed deposition of C activation products such as activated C and C5b-9 and measured sC5b-9 in the PD fluid of patients. As a result, the severity of peritoneal injuries correlated inversely with the expression of peritoneal CRegs. Peritoneal CReg expression in peritonitis was significantly reduced compared to no peritonitis. Peritoneal injuries were more severe in P1 than in P2. CReg expression was further decreased and C5b-9 further increased in P1 than in P2. In conclusion, severe peritoneal injuries due to fungal and Pseudomonas aeruginosa-peritonitis decreased CReg expression and increased deposition of activated C3 and C5b-9 in the peritoneum, suggesting that peritonitis, particularly fungal and Pseudomonas aeruginosa-peritonitis, might induce susceptibility to further peritoneal injuries due to excessive C activation.

Neutrophil extracellular trap inhibition improves survival in neonatal mouse infectious peritonitis.

BACKGROUND: Treatment of neonatal peritonitis and sepsis is challenging. Following infection, neutrophils elaborate neutrophil extracellular traps (NETs)-extracellular lattices of decondensed chromatin decorated with antimicrobial proteins. NETs, however, can augment pathogenic inflammation causing collateral damage. We hypothesized that NET inhibition would improve survival in experimental neonatal infectious peritonitis. METHODS: We induced peritonitis in 7 to 10-day-old mice by intraperitoneal injection with cecal slurry. We targeted NETs by treating mice with neonatal NET-Inhibitory Factor (nNIF), an endogenous NET-inhibitor; Cl-amidine, a PAD4 inhibitor; DNase I, a NET degrading enzyme, or meropenem (an antibiotic). We determined peritoneal NET and cytokine levels and circulating platelet-neutrophil aggregates. Survival from peritonitis was followed for 6 days. RESULTS: nNIF, Cl-amidine, and DNase I decreased peritoneal NET formation and inflammatory cytokine levels at 24 h compared to controls. nNIF, Cl-amidine, and DNase I decreased circulating platelet-neutrophil aggregates, and NET-targeting treatments significantly increased survival from infectious peritonitis compared to controls. Finally, nNIF administration significantly improved survival in mice treated with sub-optimal doses of meropenem even when treatment was delayed until 2 h after peritonitis induction. CONCLUSIONS: NET inhibition improves survival in experimental neonatal infectious peritonitis, suggesting that NETs participate pathogenically in neonatal peritonitis and sepsis. IMPACT: 1. Neutrophil extracellular trap formation participates pathogenically in experimental neonatal infectious peritonitis. 2. NET-targeting strategies improve outcomes in a translational model of neonatal infectious peritonitis. 3. NET inhibition represents a potential target for drug development in neonatal sepsis and infectious peritonitis.

A forensic case of abdominal cocoon syndrome.

The term "cocoon syndrome" defines a sclerosing encapsulating peritonitis (SEP) that involves a chronic fibrotic inflammatory reaction of the parietal peritoneum and of the viscera leading to a complete sclerosis. The cocoon that is formed causes an incarceration of the intestinal loops with severe complications leading to high mortality. We are presenting the case of a 15-year-old young man that underwent surgery for appendectomy and that was evaluated for having a regular abdominal state. During the post-surgery period, however, several episodes of intestinal occlusion required further surgical interventions leading to a right hemicolectomy. The presence of a fibrotic-adhesive ligneous peritonitis with blended intestinal loops, severely thickened walls, and intestinal scaring stenosis was observed during his second surgical operation. A stenosis of the colostomy led to a worsening of the vital signs of the young man with the onset of a cardiac failure and subsequent decease. Macroscopic autopsy examination and histological analysis confirmed the severe obstructive adhesive encapsulating abdominal context allowing to trace back the cause of death to a cocoon syndrome. Since no predisposing factor could be found, we hypothesized that this case could be characterized by an excessive peritoneal reactivity due to surgical appendectomy. Cocoon syndrome is a rare pathology, and its microscopic features are seldomly observed and could be underestimated. We present a directly observed case with a very substantial macroscopic and microscopic context.

Characterizing Salmonella Typhimurium-induced Septic Peritonitis in Mice.

Sepsis is a dysregulated host immune response to microbial invasion or tissue damage, leading to organ injury at a site distant from that of the infection or damage. Currently, the widely used mice models of sepsis include lipopolysaccharide (LPS)-induced endotoxemia, cecal ligation and puncture (CLP), and monobacterial infection model systems. This protocol describes a method to study the host responses during Salmonella Typhimurium infection-induced septic peritonitis in mice. S. Typhimurium, a Gram-negative intracellular pathogen, causes typhoid-like disease in mice. This protocol elaborates the culture preparation, induction of septic peritonitis in mice through intraperitoneal injection, and methods to study systemic host responses. Furthermore, the assessment of bacterial burden in different organs and the flow cytometric analysis of increased neutrophil numbers in the peritoneal lavage is presented. Salmonella Typhimurium-induced sepsis in mice leads to an increase in proinflammatory cytokines and rapid infiltration of neutrophils in the peritoneal cavity, leading to lower survival. Every step in this protocol has been optimized, resulting in high reproducibility of the pathogenesis of septic peritonitis. This model is useful for studying immunological responses during bacterial sepsis, the roles of different genes in disease progression, and the effects of drugs to attenuate sepsis.

Medullary carcinoma of jejunum presenting as perforation peritonitis: A case report.

Small intestinal medullary carcinoma (MC) is a newly recognized subclass of small intestinal carcinomas and is an exceptional entity for this site. A search of the literature for similar cases arising in the small intestine revealed only six previously reported cases. Here we present a case of MC arising in the jejunum of a 65-year-old male. The patient presented to the emergency with features of perforation peritonitis with liver metastasis and no known predisposing factors like inflammatory bowel disease and celiac disease. Studies conducted on this tumor's colonic counterpart have shown microsatellite instability (MSI) and B-type Raf kinase (BRAF) mutations; however, few exceptions are known. Also, this subtype of carcinoma is known to have a better prognosis than its other histological subtypes.

IgG4 related sclerosing encapsulating peritonitis with cocoon formation: An unusual and undescribed presentation.

IgG4-related sclerosing mesenteritis is a rare disease of mesentery of an unknown etiology which shows a constellation of histopathologic findings of lymphoplasmacytic inflammation with IgG4-positive plasma cells and marked fibrosis. This chronic inflammatory condition of mesentery forming an abdominal cocoon has never been described before to the best of our knowledge. Here, we report a patient with a history of subacute small bowel obstruction who was found to have an intra-abdominal encapsulating mass in the right iliac fossa and was finally diagnosed as IgG4-related sclerosing encapsulating peritonitis (abdominal cocoon) based on peroperative findings, histology and immunohistochemistry.

Macroscopic and histopathological features of acute peritoneal infection in diabetic and euglycemic Wistar rats.

INTRODUCTION: Impact of the secondary peritoneal infections on the peritoneal morphology in diabetic population remains unclear. AIM OF THE STUDY: To study the histopathological changes of the peritoneum due to secondary bacterial peritonitis in diabetic rats in compari-son to the normoglycemic animals. MATERIAL AND METHODS: 13 adult male Wistar rats were divided into 2 groups: control (n = 3) and experimental (n = 10). The latter was subdivided into non-diabetic (n = 5) and diabetic (n = 5). T1DM and peritonitis were induced through the single intraperitoneal injec-tion of Streptozotocin (60 mg/kg) and intraperitoneal injection of 2 ml of the faecal matter, respectively. RESULTS: Macroscopic findings of diabetic rat peritoneum included significant accumulation of the exudate in the peritoneal cavity and presence of intraintestinal adhesions and abscesses. Morphology of the peritonium presented with diffuse, profound degenerative and inflammatory lesions involving the subjacent tissues. In contrast, the underlying muscular layer of the non-diabetic rats remained intact. CONCLUSIONS: Natural course of the peritoneal infection in diabetic rats (48 hours) is characterised by diffuse severe peritonitis with inter-intestinal abscess formation and more profound subadjacent tissue involvement in comparison with non-diabetic rats.

[Change of innate lymphoid cell subsets in peripheral bloods and ascites in liver cirrhotic patients complicated with spontaneous bacterial peritonitis].

Objective: To investigate the change of innate lymphoid cells (ILC) subsets in peripheral blood and ascites in liver cirrhotic patients complicated with spontaneous bacterial peritonitis (SBP). Methods: The data of 62 patients with liver cirrhosis admited to the Zhumadian Central Hospital from November 2019 to November 2020 were analyzed. Among them, 41 cases were complicated with untainted ascites (untainted ascites group), while the other 21 cases were complicated with SBP (SBP group). Meanwhile, 20 cases of controls who received healthy examination in the same period were also enrolled (control group). Peripheral blood mononuclear cell (PBMC) was isolated from peripheral blood of all patients and controls. Mononuclear cell in ascites was isolated from patients with liver cirrhosis. The percentage of ILC1, ILC2, and ILC3 subsets in PBMC and mononuclear cell in ascites were measured by flow cytometry. CD3-CD19-CD20-CD14- cells (lin-cells) were purified from ascites and were stimulated with lipopolysaccharide (LPS) for 24 h. The transcription factor T-bet, GATA3, and RORγt mRNA relative level in lin-cells was semi-quantified by real-time PCR. Cytokine level in the supernatants was measured by enzyme linked immunosorbent assay. Differences of ILC subsets in peripheral blood and ascites were compared among groups. Results: There were twenty-nine males and twelve females in untainted ascites group, aged M(Q1,Q3) 49(33, 78) years. There were twelve males and nine females in SBP group, aged 50(37, 76) years. There were eleven males and nine females in control group, aged 48(32, 69) years. lin-CD45+CD161+CD127+ ILC cells could be detected in both peripheral blood and ascites. There was no significant difference in total ILC percentage within PBMC among untainted ascites group, SBP group, and control group (P=0.235). There was also no significant difference of total ILC percentage within mononuclear cells in ascites between untainted ascites group and SBP group (P=0.232). The differences were not statistically significant of peripheral CD117-CRTh2-ILC1, CRTh2+ILC2, or CD117+CRTh2-ILC3 within peripheral ILC among untainted ascites group, SBP group, and control group (all P>0.05). ILC1 percentage in ascites was up-regulated in SBP group compared with untainted ascites group (35.69%±3.39% vs 26.40%±3.85%, P<0.001), while ILC2 in ascites was down-regulated in SBP group (36.83%±7.70% vs 48.35%±9.45%, P<0.001). There was no statistical difference in ILC3 percentage in ascites between the two groups (P=0.230). T-bet mRNA relative level and IFN-γ production by lin- cells from ascites were elevated in response to LPS stimulation in SBP group compared with untainted ascites group (both P<0.001). GATA3 mRNA relative level and IL-5/IL-13 secretion by lin-cells from ascites were reduced in SBP group compared with untainted ascites group (both P<0.05). There was no significant difference of RORγt mRNA relative level or IL-17/IL-22 expression between the two groups (both P>0.05). Conclusion: Peripheral ILC subsets do not change in liver cirrhosis patients with SBP. ILC1 percentage is up-regulated, and ILC2 percentage is down-regulated in ascites in liver cirrhosis patients with SBP.

Oxylipin metabolism is controlled by mitochondrial ß-oxidation during bacterial inflammation.

Oxylipins are potent biological mediators requiring strict control, but how they are removed en masse during infection and inflammation is unknown. Here we show that lipopolysaccharide (LPS) dynamically enhances oxylipin removal via mitochondrial ß-oxidation. Specifically, genetic or pharmacological targeting of carnitine palmitoyl transferase 1 (CPT1), a mitochondrial importer of fatty acids, reveal that many oxylipins are removed by this protein during inflammation in vitro and in vivo. Using stable isotope-tracing lipidomics, we find secretion-reuptake recycling for 12-HETE and its intermediate metabolites. Meanwhile, oxylipin ß-oxidation is uncoupled from oxidative phosphorylation, thus not contributing to energy generation. Testing for genetic control checkpoints, transcriptional interrogation of human neonatal sepsis finds upregulation of many genes involved in mitochondrial removal of long-chain fatty acyls, such as ACSL1,3,4, ACADVL, CPT1B, CPT2 and HADHB. Also, ACSL1/Acsl1 upregulation is consistently observed following the treatment of human/murine macrophages with LPS and IFN-γ. Last, dampening oxylipin levels by ß-oxidation is suggested to impact on their regulation of leukocyte functions. In summary, we propose mitochondrial ß-oxidation as a regulatory metabolic checkpoint for oxylipins during inflammation.

Effects of Formyl Peptide Receptor Agonists Ac9-12 and WKYMV in In Vivo and In Vitro Acute Inflammatory Experimental Models.

Formyl peptide receptors (Fprs) are a G-protein-coupled receptor family mainly expressed on leukocytes. The activation of Fpr1 and Fpr2 triggers a cascade of signaling events, leading to leukocyte migration, cytokine release, and increased phagocytosis. In this study, we evaluate the effects of the Fpr1 and Fpr2 agonists Ac9-12 and WKYMV, respectively, in carrageenan-induced acute peritonitis and LPS-stimulated macrophages. Peritonitis was induced in male C57BL/6 mice through the intraperitoneal injection of 1 mL of 3% carrageenan solution or saline (control). Pre-treatments with Ac9-12 and WKYMV reduced leukocyte influx to the peritoneal cavity, particularly neutrophils and monocytes, and the release of IL-1ß. The addition of the Fpr2 antagonist WRW4 reversed only the anti-inflammatory actions of WKYMV. In vitro, the administration of Boc2 and WRW4 reversed the effects of Ac9-12 and WKYMV, respectively, in the production of IL-6 by LPS-stimulated macrophages. These biological effects of peptides were differently regulated by ERK and p38 signaling pathways. Lipidomic analysis evidenced that Ac9-12 and WKYMV altered the intracellular lipid profile of LPS-stimulated macrophages, revealing an increased concentration of several glycerophospholipids, suggesting regulation of inflammatory pathways triggered by LPS. Overall, our data indicate the therapeutic potential of Ac9-12 and WKYMV via Fpr1 or Fpr2-activation in the inflammatory response and macrophage activation.

IL-33 priming amplifies ATP-mediated mast cell cytokine production.

Inflammatory responses are required to block pathogen infection but can also lead to hypersensitivity and chronic inflammation. Barrier tissues actively release IL-33, ATP, and other alarmins during cell stress, helping identify pathogenic stimuli. However, it is unclear how these signals are integrated. Mast cells are critical initiators of allergic inflammation and respond to IL-33 and ATP. We found that mouse mast cells had a 3-6-fold increase in ATP-induced cytokine production when pre-treated with IL-33. This effect was observed at ATP concentrations < 100 µM and required < 30-minute IL-33 exposure. ATP-induced degranulation was not enhanced by pretreatment nor was the response to several pathogen molecules. Mechanistic studies implicated the P2X7 receptor and calcineurin/NFAT pathway in the enhanced ATP response. Finally, we found that IL-33 + ATP co-stimulation enhanced peritoneal eosinophil and macrophage recruitment. These results support the hypothesis that alarmins collaborate to surpass a threshold necessary to initiate an inflammatory response.

Sida tuberculata: In vitro cytotoxicity and in vivo anti-inflammatory effect.

ETHNOPHARMACOLOGICAL RELEVANCE: Sida tuberculata R. E. Fries (Malvaceae) is a pioneer species considered a weed in farm fields in Southern Brazil. Widely distributed in South Brazil, S. tuberculata is popularly used to treat inflammatory conditions. AIMS OF THE STUDY: The current study aimed to assess the in vitro cytotoxic and in vivo anti-inflammatory properties of S. tuberculata. MATERIALS AND METHODS: Initially, extracts obtained from leaves (STLE) and roots (STRE) were submitted to cytotoxicity tests using human leukocytes (non-malignant cell line) and HepG2 and MCF-7 (tumor cell lines). In sequence, anti-inflammatory properties were investigated against carrageenan-induced peritonitis model. RESULTS: In vitro analyses displayed a significant decrease in human leukocytes viability without genotoxic damage. IC50 results from tumor cells presented significant decrease in cell viability, slightly more pronounced for STRE. In addition, STLE significantly inhibited the inflammatory and oxidative parameters (TBARS, NPSH, SOD, MPO activity, cell influx, and cytokines release). CONCLUSION: Our findings indicate S. tuberculata extracts have cytotoxic potential more pronounced on tumor cell lines, as well as leaves extract shows a significant reduction in acute inflammation process, as already reported for Sida genus and specifically for this species.

Guizhi-Shaoyao-Zhimu decoction attenuates monosodium urate crystal-induced inflammation through inactivation of NF-κB and NLRP3 inflammasome.

ETHNOPHARMACOLOGICAL RELEVANCE: Guizhi-Shaoyao-Zhimu decoction (GSZD), a classical traditional Chinese medicine (TCM) prescription, is used empirically to treat various types of arthritis in TCM clinical practice. However, the underlying mechanisms of GSZD on gouty inflammation are not totally elucidated. AIM OF STUDY: The purpose of this study is to investigate the effects of GSZD on peritoneal recruitment of neutrophils, production of proinflammatory mediators, activations of nuclear factor (NF)-κB and nucleotide oligomerization domain-like receptor protein-3 (NLRP3) inflammasome in mice with monosodium urate crystal (MSU)-induced peritonitis (MIP). MATERIALS AND METHODS: Mice were intragastrically administered with GSZD for 7 days. After the last administration, mice were intraperitoneally injected with MSU. Peritoneal exudates of mice were harvested, and total peritoneal cells were calculated. Levels of interleukin (IL)-1ß, IL-6 and monocyte chemotactic protein (MCP)-1 in peritoneal exudates were tested by enzyme-linked immunosorbent assay. Expressions of IL-1ß, NLRP3, cysteinyl aspartate specific proteinase (caspase)-1, apoptosis-associated speck-like protein containing the caspase activation and recruitment domain (ASC), phosphorylated (p)-p65, inhibitor of NF-κB (IκB)α, p-IκB kinase (IKK)ß, nuclear p65, p-mitogen-activated protein kinases (MAPKs) in peritoneal cells were analyzed by Western blot. Binding activity of NF-κB to DNA was measured by a Trans AM™ kit for p65. Interaction between ASC and pro-caspase-1 was assessed by co-immunoprecipitation assay. RESULTS: Total peritoneal cells, levels of IL-1ß, IL-6 and MCP-1 were significantly reduced by GSZD treatment in peritoneal exudates of MIP mice. As for the activation of NF-κB, GSZD treatment significantly reduced the levels of p-p65, p-IKKß, nuclear p65 and p-MAPKs, enhanced the level of IκBα and abated the binding ability of NF-κB to DNA in peritoneal cells of MIP mice. As for the activation of NLRP3 inflammasome, GSZD treatment significantly reduced the levels of IL-1ß, NLRP3 and caspase-1, and alleviated the interaction between ASC and pro-caspase-1 in peritoneal cells of MIP mice. Nevertheless, GSZD didn't remarkably change the level of ASC. CONCLUSIONS: These results suggest that GSZD attenuates the MSU-induced inflammation through inhibiting the activations of NF-κB and NLRP3 inflammasome.

Intraperitoneal microbial contamination drives post-surgical peritoneal adhesions by mesothelial EGFR-signaling.

Abdominal surgeries are lifesaving procedures but can be complicated by the formation of peritoneal adhesions, intra-abdominal scars that cause intestinal obstruction, pain, infertility, and significant health costs. Despite this burden, the mechanisms underlying adhesion formation remain unclear and no cure exists. Here, we show that contamination of gut microbes increases post-surgical adhesion formation. Using genetic lineage tracing we show that adhesion myofibroblasts arise from the mesothelium. This transformation is driven by epidermal growth factor receptor (EGFR) signaling. The EGFR ligands amphiregulin and heparin-binding epidermal growth factor, are sufficient to induce these changes. Correspondingly, EGFR inhibition leads to a significant reduction of adhesion formation in mice. Adhesions isolated from human patients are enriched in EGFR positive cells of mesothelial origin and human mesothelium shows an increase of mesothelial EGFR expression during bacterial peritonitis. In conclusion, bacterial contamination drives adhesion formation through mesothelial EGFR signaling. This mechanism may represent a therapeutic target for the prevention of adhesions after intra-abdominal surgery.

Transcriptomics Changes in the Peritoneum of Mice with Lipopolysaccharide-Induced Peritonitis.

Peritonitis caused by LPS is a severe clinical challenge, which causes organ damage and death. However, the mechanism of LPS-induced peritonitis has not been fully revealed yet. Here, we investigated the transcriptome profile of the peritoneal tissue of LPS-induced peritonitis in mice. A model of LPS-induced peritonitis in mice was established (LPS 10 mg/kg, i.p.), and the influence of TAK 242 (TLR4 inhibitor) on the level of inflammatory cytokines in mouse peritoneal lavage fluid was investigated by using an ELISA test. Next, the peritoneal tissues of the three groups of mice (Control, LPS, and LPS+TAK 242) (n = 6) were isolated and subjected to RNA-seq, followed by a series of bioinformatics analyses, including differentially expressed genes (DEGs), enrichment pathway, protein-protein interaction, and transcription factor pathway. Then, qPCR verified-hub genes that may interact with TAK 242 were obtained. Subsequently, the three-dimensional structure of hub proteins was obtained by using homology modeling and molecular dynamics optimization (300 ns). Finally, the virtual docking between TAK 242 and hub proteins was analyzed. Our results showed that TAK 242 significantly inhibited the production of inflammatory cytokines in the peritoneal lavage fluid of mice with peritonitis, including IL-6, IFN-γ, IL-1ß, NO, and TNF-α. Compared with the Control group, LPS treatment induced 4201 DEGs (2442 down-regulated DEGs and 1759 up-regulated DEGs). Compared with the LPS group, 30 DEGs were affected by TAK 242 (8 down-regulated DEGs and 22 up-regulated DEGs). A total of 10 TAK 242-triggered hub genes were obtained, and the possible docking modes between TAK 242 and hub proteins were acquired. Overall, our data demonstrated that a large number of DEGs were affected in LPS-triggered peritonitis mice. Moreover, the TLR4 inhibitor TAK 242 is capable of suppressing the inflammatory response of LPS-induced peritonitis. Our work provides clues for understanding the pathogenesis of LPS-induced peritonitis in mice.

Insular cortex neurons encode and retrieve specific immune responses.

Increasing evidence indicates that the brain regulates peripheral immunity, yet whether and how the brain represents the state of the immune system remains unclear. Here, we show that the brain's insular cortex (InsCtx) stores immune-related information. Using activity-dependent cell labeling in mice (FosTRAP), we captured neuronal ensembles in the InsCtx that were active under two different inflammatory conditions (dextran sulfate sodium [DSS]-induced colitis and zymosan-induced peritonitis). Chemogenetic reactivation of these neuronal ensembles was sufficient to broadly retrieve the inflammatory state under which these neurons were captured. Thus, we show that the brain can store and retrieve specific immune responses, extending the classical concept of immunological memory to neuronal representations of inflammatory information.