Propofol improves survival in a murine model of sepsis via inhibiting Rab5a-mediated intracellular trafficking of TLR4.

BACKGROUND: Propofol is a widely used anesthetic and sedative, which has been reported to exert an anti-inflammatory effect. TLR4 plays a critical role in coordinating the immuno-inflammatory response during sepsis. Whether propofol can act as an immunomodulator through regulating TLR4 is still unclear. Given its potential as a sepsis therapy, we investigated the mechanisms underlying the immunomodulatory activity of propofol. METHODS: The effects of propofol on TLR4 and Rab5a (a master regulator involved in intracellular trafficking of immune factors) were investigated in macrophage (from Rab5a-/- and WT mice) following treatment with lipopolysaccharide (LPS) or cecal ligation and puncture (CLP) in vitro and in vivo, and peripheral blood monocyte from sepsis patients and healthy volunteers. RESULTS: We showed that propofol reduced membrane TLR4 expression on macrophages in vitro and in vivo. Rab5a participated in TLR4 intracellular trafficking and both Rab5a expression and the interaction between Rab5a and TLR4 were inhibited by propofol. We also showed Rab5a upregulation in peripheral blood monocytes of septic patients, accompanied by increased TLR4 expression on the cell surface. Propofol downregulated the expression of Rab5a and TLR4 in these cells. CONCLUSIONS: We demonstrated that Rab5a regulates intracellular trafficking of TLR4 and that propofol reduces membrane TLR4 expression on macrophages by targeting Rab5a. Our study not only reveals a novel mechanism for the immunomodulatory effect of propofol but also indicates that Rab5a may be a potential therapeutic target against sepsis.

Gut microbiota-derived succinate aggravates acute lung injury after intestinal ischaemia/reperfusion in mice.

INTRODUCTION: Acute lung injury (ALI) is a major cause of morbidity and mortality after intestinal ischaemia/reperfusion (I/R). The gut microbiota and its metabolic byproducts act as important modulators of the gut-lung axis. This study aimed to define the role of succinate, a key microbiota metabolite, in intestinal I/R-induced ALI progression. METHODS: Gut and lung microbiota of mice subjected to intestinal I/R were analysed using 16S rRNA gene sequencing. Succinate level alterations were measured in germ-free mice or conventional mice treated with antibiotics. Succinate-induced alveolar macrophage polarisation and its effects on alveolar epithelial apoptosis were evaluated in succinate receptor 1 (Sucnr1)-deficient mice and in murine alveolar macrophages transfected with Sucnr1-short interfering RNA. Succinate levels were measured in patients undergoing cardiopulmonary bypass, including intestinal I/R. RESULTS: Succinate accumulated in lungs after intestinal I/R, and this was associated with an imbalance of succinate-producing and succinate-consuming bacteria in the gut, but not the lungs. Succinate accumulation was absent in germ-free mice and was reversed by gut microbiota depletion with antibiotics, indicating that the gut microbiota is a source of lung succinate. Moreover, succinate promoted alveolar macrophage polarisation, alveolar epithelial apoptosis and lung injury during intestinal I/R. Conversely, knockdown of Sucnr1 or blockage of SUCNR1 in vitro and in vivo reversed the effects of succinate by modulating the phosphoinositide 3-kinase-AKT/hypoxia-inducible factor-1α pathway. Plasma succinate levels significantly correlated with intestinal I/R-related lung injury after cardiopulmonary bypass. CONCLUSION: Gut microbiota-derived succinate exacerbates intestinal I/R-induced ALI through SUCNR1-dependent alveolar macrophage polarisation, identifying succinate as a novel target for gut-derived ALI in critically ill patients.

Gut-Derived Exosomes Induce Liver Injury After Intestinal Ischemia/Reperfusion by Promoting Hepatic Macrophage Polarization.

Liver injury induced by intestinal ischemia/reperfusion (I/R) is accompanied by the polarization of Kupffer cells, which are specialized macrophages located in the liver. However, the causes of hepatic macrophage polarization after intestinal I/R remain unknown. This study investigated whether gut-derived exosomes contribute to the pathogenesis of liver injury triggered by intestinal I/R in a murine model and explored the underlying mechanisms. Intestinal I/R models were established by temporally clamping the superior mesenteric arteries of mice. Exosomes were isolated from the intestinal tissue of mice that underwent intestinal I/R or sham surgery according to a centrifugation-based protocol. Exosomes were co-cultured with RAW 264.7 macrophages or injected intravenously in mice. Liposomal clodronate was administered intraperitoneally to deplete the macrophages. Macrophage polarization was determined by flow cytometry, immunohistochemistry, and quantitative polymerase chain reaction. Liver injury was assessed by histological morphology and increased serum aspartate aminotransferase and alanine aminotransferase levels. Exosomes from mice intestines subjected to I/R (IR-Exo) promoted macrophage activation in vitro. Intravenous injection of IR-Exo caused hepatic M1 macrophage polarization and led to liver injury in mice. Depleting macrophages ameliorated liver injury caused by intestinal I/R or the injection of IR-Exo. Furthermore, inhibiting exosome release improved intestinal injury, liver function, and survival rates of mice subjected to intestinal I/R. Our study provides evidence that gut-derived exosomes induce liver injury after intestinal I/R by promoting hepatic M1 macrophage polarization. Inhibition of exosome secretion could be a therapeutic target for preventing hepatic impairment after intestinal I/R.

Gut Microbial Metabolite Pravastatin Attenuates Intestinal Ischemia/Reperfusion Injury Through Promoting IL-13 Release From Type II Innate Lymphoid Cells via IL-33/ST2 Signaling.

Intestinal ischemia/reperfusion (I/R) injury is a grave condition with high morbidity and mortality. We previously confirmed that intestinal I/R induces intestinal flora disorders and changes in metabolites, but the role of different metabolites in intestinal I/R injury is currently unclear. Based on targeted metabolic sequencing, pravastatin (PA) was determined to be a metabolite of the gut microbiota. Further, intestinal I/R model mice were established through superior mesenteric artery obstruction. In addition, a co-culture model of small intestinal organoids and type II innate lymphoid cells (ILC2s) was subjected to hypoxia/reoxygenation (H/R) to simulate an intestinal I/R model. Moreover, correlation analysis between the PA level in preoperative feces of patients undergoing cardiopulmonary bypass and the indices of postoperative intestinal I/R injury was carried out. IL-33-deficient mice, ILC2-deleted mice, and anti-IL-13 neutralizing antibodies were also used to explore the potential mechanism through which PA attenuates intestinal I/R injury. We demonstrated that PA levels in the preoperative stool of patients undergoing cardiopulmonary bypass were negatively correlated with the indices of postoperative intestinal I/R injury. Furthermore, PA alleviated intestinal I/R injury and improved the survival of mice. We further showed that PA promotes IL-13 release from ILC2s by activating IL-33/ST2 signaling to attenuate intestinal I/R injury. In addition, IL-13 promoted the self-renewal of intestinal stem cells by activating Notch1 and Wnt signals. Overall, results indicated that the gut microbial metabolite PA can attenuate intestinal I/R injury by promoting the release of IL-13 from ILC2s via IL-33/ST2 signaling, revealing a novel mechanism of and therapeutic strategy for intestinal I/R injury.

The gut microbiota metabolite capsiate promotes Gpx4 expression by activating TRPV1 to inhibit intestinal ischemia reperfusion-induced ferroptosis.

Ferroptosis, a new type of cell death has been found to aggravate intestinal ischemia/reperfusion (I/R) injury. However, little is known about the changes of gut microbiota and metabolites in intestinal I/R and the role of gut microbiota metabolites on ferroptosis-induced intestinal I/R injury. This study aimed to establish a mouse intestinal I/R model and ileum organoid hypoxia/reoxygenation (H/R) model to explore the changes of the gut microbiota and metabolites during intestinal I/R and protective ability of capsiate (CAT) against ferroptosis-dependent intestinal I/R injury. Intestinal I/R induced disturbance of gut microbiota and significant changes in metabolites. We found that CAT is a metabolite of the gut microbiota and that CAT levels in the preoperative stool of patients undergoing cardiopulmonary bypass were negatively correlated with intestinal I/R injury. Furthermore, CAT reduced ferroptosis-dependent intestinal I/R injury in vivo and in vitro. However, the protective effects of CAT against ferroptosis-dependent intestinal I/R injury were abolished by RSL3, an inhibitor of glutathione peroxidase 4 (Gpx4), which is a negative regulator of ferroptosis. We also found that the ability of CAT to promote Gpx4 expression and inhibit ferroptosis-dependent intestinal I/R injury was abrogated by JNJ-17203212, an antagonist of transient receptor potential cation channel subfamily V member 1 (TRPV1). This study suggests that the gut microbiota metabolite CAT enhances Gpx4 expression and inhibits ferroptosis by activating TRPV1 in intestinal I/R injury, providing a potential avenue for the management of intestinal I/R injury.

Presentation of gallbladder torsion at an abnormal position: A case report.

BACKGROUND: Gallbladder torsion is a rare acute abdominal condition that requires emergency surgery. It occurs more commonly in elderly people and in women in the adult population. Diagnosis is a challenge as non-specific symptoms and signs have been reported on ultrasonography, computed tomography and magnetic resonance imaging. Prompt cholecystectomy can decrease the mortality and morbidity of perforation due to gallbladder torsion. CASE SUMMARY: An 82-year-old woman with upper-right quadrant pain and associated nausea and vomiting was diagnosed with ectopic acute calculus cholecystitis. Magnetic resonance cholangiopancreatography (MRCP) showed a V-shaped distortion of the extrahepatic bile ducts and a particularly extended twisted cystic duct, which indicated the presence of gallbladder torsion. Emergency laparoscopic cholecystectomy confirmed the diagnosis and the patient recovered without incident. CONCLUSION: Gallbladder torsion can be diagnosed pre-operatively by MRCP. The specific signs are a V-shaped distortion of the extrahepatic bile ducts and a particularly extended twisted cystic duct which can be called twisting signs.

6-Gingerol attenuates macrophages pyroptosis via the inhibition of MAPK signaling pathways and predicts a good prognosis in sepsis.

BACKGROUND: Sepsis is a major cause of death for ICU patients. Sepsis development depends heavily on the presence of mature IL-1ß cytokine. This study evaluates the potential therapeutic properties of a bioactive compound known as 6-gingerol on sepsis. This compound has previously been demonstrated to possess anti-inflammatory properties both in vivo and in vitro. METHODS: C57BL/6 mice was used to establish models of sepsis by means of cecal ligation and puncture (CLP). Upon treatment with 6-gingerol, we assessed the survival rate of mice and measured the levels of key pro-inflammatory cytokines in serum and colon tissues. Sepsis pathogenesis was further explored using the RAW264.7 cell line and bone marrow-derived macrophages (BMDMs) treated with ATP and lipopolysaccharide (LPS). The impact of 6-gingerol on pyroptosis was also examined. In addition, we assessed the role of MAPK signaling in 6-gingerol-induced effects in BMDMs and RAW264.7 cells. RESULTS: In CLP mice, 6-gingerol significantly ameliorated sepsis development, which was associated with the reduction of serum IL-1ß. In BMDMs and RAW264.7 cells, 6-gingerol strongly attenuated pyroptosis as well as the release of caspase-1p20, HMGB1, mature IL-1ß, IL-18 in response to ATP and LPS treatment. 6-Gingerol conferred these effects by blocking MAPK activation. Exposure to an ERK agonist (EGF) reversed effects of 6-gingerol, causing pyroptosis, LDH and caspase-1p20 release. CONCLUSIONS: By targeting MAPK signaling, 6-gingerol significantly suppressed secretion of pro-inflammatory cytokines and inhibited macrophage cells pyroptosis resulting in overall inhibition of sepsis development.