Exosomal PGE2 from M2 macrophages inhibits neutrophil recruitment and NET formation through lipid mediator class switching in sepsis.

BACKGROUND: Excess polymorphonuclear neutrophil (PMN) recruitment or excessive neutrophil extracellular trap (NET) formation can lead to the development of multiple organ dysfunction during sepsis. M2 macrophage-derived exosomes (M2-Exos) have exhibited anti-inflammatory activities in some inflammatory diseases to mediate organ functional protection, but their role in treating sepsis-related acute lung injury (ALI) remains unclear. In this study, we sought to investigate whether M2-Exos could prevent potentially deleterious inflammatory effects during sepsis-related ALI by modulating abnormal PMN behaviours. METHODS: C57BL/6 wild-type mice were subjected to a caecal ligation and puncture (CLP) mouse model to mimic sepsis in vivo, and M2-Exos were administered intraperitoneally 1 h after CLP. H&E staining, immunofluorescence and immunohistochemistry were conducted to investigate lung tissue injury, PMN infiltration and NET formation in the lung. We further demonstrated the role of M2-Exos on PMN function and explored the potential mechanisms through an in vitro coculture experiment using PMNs isolated from both healthy volunteers and septic patients. RESULTS: Here, we report that M2-Exos inhibited PMN migration and NET formation, alleviated lung injury and reduced mortality in a sepsis mouse model. In vitro, M2-Exos significantly decreased PMN migration and NET formation capacity, leading to lipid mediator class switching from proinflammatory leukotriene B4 (LTB4) to anti-inflammatory lipoxin A4 (LXA4) by upregulating 15-lipoxygenase (15-LO) expression in PMNs. Treatment with LXA4 receptor antagonist attenuated the effect of M2-Exos on PMNs and lung injury. Mechanistically, prostaglandin E2 (PGE2) enriched in M2-Exos was necessary to increase 15-LO expression in PMNs by functioning on the EP4 receptor, upregulate LXA4 production to downregulate chemokine (C-X-C motif) receptor 2 (CXCR2) and reactive oxygen species (ROS) expressions, and finally inhibit PMN function. CONCLUSIONS: Our findings reveal a previously unknown role of M2-Exos in regulating PMN migration and NET formation through lipid mediator class switching, thus highlighting the potential application of M2-Exos in controlling PMN-mediated tissue injury in patients with sepsis.

Efficacy of initial caspofungin plus trimethoprim/sulfamethoxazole for severe PCP in patients without human immunodeficiency virus infection.

BACKGROUND: The number of pneumocystis pneumonia (PCP) cases is increasing in immunocompromised patients without human immunodeficiency virus infection (HIV), causing serious morbidity with high mortality. Trimethoprim/sulfamethoxazole (TMP/SMZ) monotherapy has limited effectiveness in the treatment of PCP. Clinical data on whether initial caspofungin plus TMP/SMZ for this disease is superior to monotherapy in non-HIV-infected patients are limited. We aimed to compare the clinical effectiveness of these regimens for severe PCP in non-HIV patients. METHODS: A retrospective study reviewed 104 non-HIV-infected patients with confirmed PCP in the intensive care unit between January 2016 and December 2021. Eleven patients were excluded from the study because TMP/SMZ could not be used due to severe hematologic disorders or clinical data were missing. All enrolled patients were divided into three groups according to different treatment strategies: Group 1 received TMP/SMZ monotherapy, Group 2 received caspofungin combined with TMP/SMZ as first-line therapy, and Group 3 initially received TMP/SMZ monotherapy and later received caspofungin as salvage therapy. The clinical characteristics and outcomes were compared among the groups. RESULTS: A total of 93 patients met the criteria. The overall positive response rate of anti-PCP treatment was 58.06%, and the overall 90-day all-cause mortality rate was 49.46%. The median APACHE II score was 21.44. The concurrent infection rate was 74.19%, among whom 15.05% (n = 14) of those patients had pulmonary aspergillosis, 21.05% (n = 20) had bacteremia, and 23.65% (n = 22) had CMV infections. The patients who received initial caspofungin combination with TMP/SMZ had the best positive response rate (76.74%) compared to others (p = 0.001). Furthermore, the group that received initial caspofungin combined with TMP/SMZ had a 90-day all-cause mortality rate (39.53%) that was significantly different from that of the shift group (65.51%, p = 0.024), but this rate showed no statistically significant difference compared with that in the monotherapy group (48.62%, p = 0.322). None of the patients had serious adverse events from caspofungin therapy. CONCLUSIONS: For non-HIV-infected patients with severe PCP, initial combination therapy with caspofungin and TMP/SMZ is a promising first-line treatment option compared with TMP/SMZ monotherapy and combination therapy as salvage therapy.

Trefoil factor-2, an early predictor for acute gastrointestinal injury in patients with acute pancreatitis.

ABSTRACT: Acute gastrointestinal injury (AGI) is commonly present in patients with acute pancreatitis (AP). It is often difficult to predict gastrointestinal function in the early stage due to lack of reliable markers. We aimed to assess whether early plasma trefoil factor 2 (TFF-2) is a potential predictor for AGI.Fifty one patients were included for the onset of AP (from developing abdominal pain) within 72 hours in this prospective observational single-center study from January 2013 to July 2015. Among them 23 patients were classified as mild, 17 as moderately severe, and 11 as severe according to 2012 Atlanta classification. Plasma samples were collected only once at admission to the ICU. Twenty samples of healthy adults were also collected as control. The TFF-2 levels were determined by using a human TFF-2 enzyme-linked immunoassay. AGI grades from 1st to 7th day after admission were observed.The plasma TFF-2 levels among AP patients in early stage were significantly higher than healthy controls (766.41 ng/mL vs 94.37 ng/mL, P < .0001). The correlations between TFF-2 levels and AGI grades from 1st to 4th day after admission were positive (r = 0.47, 0.43, 0.42, 0.40 respectively, P < .05). As a predictor of acute gastrointestinal failure, plasma TFF-2 was superior to others: Acute Physiology and Chronic Health Evaluation II, sequential organ failure assessment, procalcitonin, C-reactive protein, serum calcium. In addition, TFF-2 increased along with the severity of AP (r = 0.554, P < .0001) and associated with Acute Physiology and Chronic Health Evaluation II, sequential organ failure assessment, C-reactive protein, serum calcium.The plasma TFF-2 levels were increased in patients in early stage of AP and correlated with AGI grades and disease severity in our study. TFF-2 might be a potential predictor for acute gastrointestinal failure in patients with AP.

TUDCA Ameliorates Liver Injury Via Activation of SIRT1-FXR Signaling in a Rat Hemorrhagic Shock Model.

OBJECTIVE: The aim of this study was to investigate the changes of bile acids in the liver during hemorrhagic shock (HS) and their potential to attenuate liver injury via activation of SIRT1 (sirtuin 1)-FXR (farnesoid X receptor) signaling. METHODS: A Sprague-Dawley (SD) rat HS model was established, whereas HepG2 cells were hypoxically cultured to simulate HS in vitro. Liver bile acids (BA) were profiled with ultraperformance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). FXR expression was detected by western blot and immunohistochemistry. The mRNA levels of SIRT1 and FXR were detected by polymerase chain reaction. Protein expression of SIRT1, FoxM1, NF-κB, acetyl-NF-κB, p53, and acetyl-p53 was analyzed by western blot. Hepatocyte apoptosis and proliferation were measured by TUNEL assay and Ki-67 staining, respectively. Serum and supernatant cytokines were analyzed using ELISA assays. Liver injury was also assessed. To investigate the possible mechanisms, SIRT1 agonist (SRT1720), SIRT1 inhibitor (EX527), and FXR inhibitor (Z-guggulsterone) were used. RESULTS: Tauroursodeoxycholic acid (TUDCA) in the liver decreased significantly after HS. SIRT1 and FXR expression was time-dependently downregulated by HS or hypoxia condition. TUDCA upregulated SIRT1-FXR activity, which inhibited expression and acetylation of NF-κB and p53 and increased FoxM1 expression, leading to decreased inflammatory response and apoptosis and increased proliferative capacity in hepatocytes, and attenuation of liver injury. EX527 pretreatment reversed the protective effect of TUDCA. Moreover, Z-guggulsterone supplementation decreased the protective effect of TUDCA in vitro. CONCLUSION: TUDCA in the liver decreased during HS. TUDCA supplementation might attenuate HS-induced liver injury by upregulating SIRT1-FXR signaling.

Fluid resuscitation via the rectum ameliorates hemodynamic disorders through adjusting aquaporin expression in an experimental severe acute pancreatitis model.

Acute pancreatitis is an acute abdominal disease, with 10-20% of the cases deteriorating rapidly, accompanied by persistent organ failure and further development into severe acute pancreatitis (SAP). The aim of the present study was to investigate the mechanism of fluid resuscitation via the rectum in the early stages of SAP and the role of aquaporins (AQPs). An SAP model was constructed by injection of 5% sterile sodium taurocholate into the biliopancreatic duct of Sprague Dawley rats, and the mean arterial pressure (MAP) was continuously monitored via femoral artery catheterization. At 30 min after the construction of the SAP model, the rats in the fluid resuscitation groups were resuscitated with normal saline at a rate of 4 ml/kg/h through the venous or the rectal route. The AQP and Na+-K+-ATPase levels, and the correlation of the MAP and colon AQPs at the early stages of SAP were analyzed. The results demonstrated that the mRNA level of AQP-3 and AQP-4 in the distal colon decreased significantly in the group subjected to fluid resuscitation via the rectum, while no significant differences were identified in the Na+-K+-ATPase levels of the colon in that group. Furthermore, a negative correlation was identified between the expression of AQPs and the MAP (P<0.01). Thus, fluid resuscitation via the rectum appears to ameliorate hemodynamic disorders through adjusting the expression of AQP-3 and AQP-4 in the distal colon in an experimental SAP model.

Intravenous Vitamin C attenuates hemorrhagic shock-related renal injury through the induction of SIRT1 in rats.

To investigate the effect of intravenous Vitamin C (VC) on hemorrhagic shock (HS)-associated rat renal injury and the involved mechanism. Thirty SD rats were randomly assigned to the sham surgery (sham), hemorrhagic shock (HS), HS+100 mg/kg VC (H + VL), HS+500 mg/kg VC (H + VH) and HS+100 mg/kg VC + EX527 (H + VL + E) groups. Tissue and blood samples were collected 6 h after surgery. Kidney pathological changes were scored. Creatinine (CRE), blood urea nitrogen (BUN), tumor necrosis factor-α (TNF-α), and interleukin-1ß (IL-1ß) levels in serum and Vitamin C levels and superoxide dismutase (SOD) activity and the ability to suppress hydroxyl radical (RAFHR) in plasma were measured. The expression of Sirtuin1 (SIRT1), Acetyl-NF-κB (Ace-NF-κB), heme oxygenase-1 (HO-1), TNF-α, and IL-1ß in tissues was analyzed by ELISA or western-blot. In the HS group, the kidney pathological score and CRE, BUN, TNF-α, and IL-1ß levels in serum were significantly higher than in the Sham group (P < 0.05), while SOD and RAFHR were significantly decreased in the plasma (P < 0.05). SOD activity and SIRT1 expression were remarkably lower in the kidney in the HS group than in the Sham group (P < 0.05), while MDA, TNF-α, and IL-1ß concentrations and Acetyl-NF-κB andHO-1 expression in the kidney showed a noteworthy increase compared to the Sham group (P < 0.05). Compared to the HS group, VC treatment led to a remarkable reduction in the kidney pathological score and CRE,BUN,TNF-α, and IL-1ß levels (P < 0.05), and a significant increase in Vitamin C, SOD, and RAFHR levels in the plasma (P < 0.05). Additionally, MDA, TNF-α, IL-1ß and Acetyl-NF-κB expression levels were decreased in the kidney (P < 0.05), while SOD, SIRT1 and HO-1 levels were notably enhanced. There were no differences between the H + VL and H + VH groups aside from plasma Vitamin C levels. The effect of Vitamin C was decreased after the addition of EX527, which inhibits SIRT1. Intravenous Vitamin C might attenuate HS-related renal injury via the SIRT1 pathway, and it appears that there were no differences in the effects between the high and low doses.

Increased frequency of circulating Tfh cells in patients with acute pancreatitis.

Considered as true helper cells for B cells in antibody response, Tfh cells are associated with inflammation and immune abnormality. Acute pancreatitis is an acute abdominal disease characterized by inflammatory response and immune disorder. Thus, our objective was to study the frequency of circulating Tfh cells, together with the Tfh cell-related CD4+ T cells and inflammatory factors in patients with acute pancreatitis. We first examined the frequency of circulating Tfh cell subsets by detecting the expression of CXCR5, PD-1, ICOS and IL-21 by flow cytometry analysis. Then we investigated the abundance of helper T cells and Treg cells. In addition, the plasma level of IgA, IgM, and Tfh cell-related inflammatory factor were detected by cytometric bead array. We showed that the frequency of circulating Tfh cells increased significantly in patients of acute pancreatitis, including CD4+CXCR5+ cells, CD4+CXCR5+PD-1+ cells, CD4+CXCR5+ICOS+ cells, and CD4+CXCR5+IL-21+ cells. Also, increases in plasma IL-1, IL-6, IL-8, IL-17, IL-21 and IgA were observed in patients with acute pancreatitis compared to HCs. This finding indicates that Tfh cells play a vital role in the development and progression of acute pancreatitis that is dependent on IL-6 and IL-21.