Sepsis is a leading cause of death in the United States, but the mechanisms underlying sepsis-induced immune dysregulation remain poorly understood. 2B4 (CD244, SLAM4) is a cosignaling molecule expressed predominantly on NK cells and memory CD8+ T cells that has been shown to regulate T cell function in models of viral infection and autoimmunity. In this article, we show that 2B4 signaling mediates sepsis lymphocyte dysfunction and mortality. 2B4 expression is increased on CD4+ T cells in septic animals and human patients at early time points. Importantly, genetic loss or pharmacologic inhibition of 2B4 significantly increased survival in a murine cecal ligation and puncture model. Further, CD4-specific conditional knockouts showed that 2B4 functions on CD4+ T cell populations in a cell-intrinsic manner and modulates adaptive and innate immune responses during sepsis. Our results illuminate a novel role for 2B4 coinhibitory signaling on CD4+ T cells in mediating immune dysregulation.
Epidermal growth factor (EGF) is a cytoprotective protein that improves survival in preclinical models of sepsis through its beneficial effects on intestinal integrity. Alcohol use disorder worsens intestinal integrity and is associated with increased morbidity and mortality in critical illness.We sought to determine whether chronic alcohol ingestion alters the host response to systemic administration of EGF in sepsis. Six-week-old FVB/N mice were randomized to receive 20% alcohol or water for 12 weeks. All mice then underwent cecal ligation and puncture to induce polymicrobial sepsis. Mice were then randomized to receive either intraperitoneal injection of EGF (150μg/kg/day) or normal saline. Water-fed mice given EGF had decreased 7-day mortality compared with water-fed mice (18% vs. 55%). Alcohol-fed mice given EGF also had decreased 7-day mortality compared with alcohol-fed mice (48% vs. 79%). Notably, while systemic EGF improved absolute survival to a similar degree in both water-fed and alcohol-fed mice, mortality was significantly higher in alcohol+EGF mice compared with water+EGF mice. Compared with water-fed septic mice, alcohol-fed septic mice had worsened intestinal integrity with intestinal hyperpermeability, increased intestinal epithelial apoptosis, decreased proliferation and shorter villus length. Systemic administration of EGF to septic alcohol-fed mice decreased intestinal permeability compared with septic alcohol-fed mice given vehicle, with increased levels of the tight junction mediators claudin-5 and JAM-A. Systemic administration of EGF to septic alcohol-fed mice also decreased intestinal apoptosis with an improvement in the Bax/ Bcl-2 ratio. EGF also improved both crypt proliferation and villus length in septic alcohol-fed mice. EGF administration resulted in lower levels of both pro- and anti-inflammatory cytokines monocyte chemoattractant protein-1, tumor necrosis factor, and interleukin 10 in alcohol-fed mice. EGF is therefore effective at improving both intestinal integrity and mortality following sepsis in mice with chronic alcohol ingestion. However, the efficacy of EGF in sepsis is blunted in the setting of chronic alcohol ingestion, as intestinal integrity and mortality in alcohol-fed mice given EGF improves animals to levels seen in water-fed mice given vehicle but does not approach levels seen in water-fed mice given EGF.
Development of primary graft dysfunction (PGD) is associated with poor outcomes after transplantation. We hypothesized that Receptor for Advanced Glycation End-products (RAGE) levels in donor lungs is associated with the development of PGD. Furthermore, we hypothesized that RAGE levels would be increased with PGD in recipients after transplantation.
We measured RAGE in bronchoalveolar lavage fluid (BALf) from 25 donors and 34 recipients. RAGE was also detected in biopsies (TBBX) from recipients with and without PGD.
RAGE levels were significantly higher in donor lungs that subsequently developed sustained PGD vs transplanted lungs that did not display PGD. Donor RAGE level was a predictor of recipient PGD (odds ratio = 1.768 per 0.25 ng/ml increase in donor RAGE level). In addition, RAGE levels remained high at 14 days in those recipients that developed severe graft dysfunction.
Recipients may be at higher risk for developing PGD if they receive transplanted organs that have higher levels of soluble RAGE prior to explantation. Moreover, the clinical and pathologic abnormalities associated with PGD post-transplantation are associated with increased RAGE expression. These findings also raise the possibility that targeting the RAGE signaling pathway could be a novel strategy for treatment and/or prevention of PGD.
Purpose: Gastric fundoplication (GF) for gastroesophageal reflux disease (GERD) may protect against the progression of chronic rejection in lung transplant (LT) recipients. However, the association of GERD with acute rejection episodes (ARE) is uncertain. This study sought to identify if ARE were linked to GERD in LT patients.
Methods: This single-center retrospective observational study, of patients transplanted from January 1, 2000, to January 31, 2009, correlated results of pH probe testing for GERD with ARE (≥International Society for Heart and Lung Transplantation A1 or B1). We compared the rates of ARE among patients with GERD (DeMeester Score > 14.7) versus without GERD as number of ARE per 1,000 patient-days after LT. Patients undergoing GF prior to LT were excluded.
Results: The analysis included 60 LT subjects and 9,249 patient-days: 33 with GERD versus 27 without GERD. We observed 51 ARE among 60 LT recipients. The rate of ARE was highest among patients with GERD: 8.49 versus 2.58, an incidence density ratio (IDR) of 3.29 (P = .00016). Upon multivariate negative binomial regression modeling, only GERD was associated with ARE (IDR 2.15; P = .009). Furthermore, GERD was associated with multiple ARE (36.4% vs 0%; P < .0001) and earlier onset compared with patients without GERD: ARE proportion at 2 months was 0.55 versus 0.26 P = .004).
Conclusion: In LT recipients, GERD was associated with a higher rate, multiple events, and earlier onset of ARE. The efficacy of GF to reduce ARE among patients with GERD needs further evaluation.