CD14+ CD15- HLA-DR- myeloid-derived suppressor cells impair antimicrobial responses in patients with acute-on-chronic liver failure.

OBJECTIVE: Immune paresis in patients with acute-on-chronic liver failure (ACLF) accounts for infection susceptibility and increased mortality. Immunosuppressive mononuclear CD14+HLA-DR- myeloid-derived suppressor cells (M-MDSCs) have recently been identified to quell antimicrobial responses in immune-mediated diseases. We sought to delineate the function and derivation of M-MDSC in patients with ACLF, and explore potential targets to augment antimicrobial responses. DESIGN: Patients with ACLF (n=41) were compared with healthy subjects (n=25) and patients with cirrhosis (n=22) or acute liver failure (n=30). CD14+CD15-CD11b+HLA-DR- cells were identified as per definition of M-MDSC and detailed immunophenotypic analyses were performed. Suppression of T cell activation was assessed by mixed lymphocyte reaction. Assessment of innate immune function included cytokine expression in response to Toll-like receptor (TLR-2, TLR-4 and TLR-9) stimulation and phagocytosis assays using flow cytometry and live cell imaging-based techniques. RESULTS: Circulating CD14+CD15-CD11b+HLA-DR- M-MDSCs were markedly expanded in patients with ACLF (55% of CD14+ cells). M-MDSC displayed immunosuppressive properties, significantly decreasing T cell proliferation (p=0.01), producing less tumour necrosis factor-alpha/interleukin-6 in response to TLR stimulation (all p<0.01), and reduced bacterial uptake of Escherichia coli (p<0.001). Persistently low expression of HLA-DR during disease evolution was linked to secondary infection and 28-day mortality. Recurrent TLR-2 and TLR-4 stimulation expanded M-MDSC in vitro. By contrast, TLR-3 agonism reconstituted HLA-DR expression and innate immune function ex vivo. CONCLUSION: Immunosuppressive CD14+HLA-DR- M-MDSCs are expanded in patients with ACLF. They were depicted by suppressing T cell function, attenuated antimicrobial innate immune responses, linked to secondary infection, disease severity and prognosis. TLR-3 agonism reversed M-MDSC expansion and innate immune function and merits further evaluation as potential immunotherapeutic agent

Defective monocyte oxidative burst predicts infection in alcoholic hepatitis and is associated with reduced expression of NADPH oxidase

Objective In order to explain the increased susceptibility to serious infection in alcoholic hepatitis, we evaluated monocyte phagocytosis, aberrations of associated signalling pathways and their reversibility, and whether phagocytic defects could predict subsequent infection. Design Monocytes were identified from blood samples of 42 patients with severe alcoholic hepatitis using monoclonal antibody to CD14. Phagocytosis and monocyte oxidative burst (MOB) were measured ex vivo using flow cytometry, luminometry and bacterial killing assays. Defects were related to the subsequent development of infection. Intracellular signalling pathways were investigated using western blotting and PCR. Interferon-γ (IFN-γ) was evaluated for its therapeutic potential in reversing phagocytic defects. Paired longitudinal samples were used to evaluate the effect of in vivo prednisolone therapy. Results MOB, production of superoxide and bacterial killing in response to Escherichia coli were markedly impaired in patients with alcoholic hepatitis. Pretreatment MOB predicted development of infection within two weeks with sensitivity and specificity that were superior to available clinical markers. Accordingly, defective MOB was associated with death at 28 and 90 days. Expression of the gp91phox subunit of nicotinamide adenine dinucleotide phosphate (NADPH) oxidase was reduced in patients with alcoholic hepatitis demonstrating defective MOB. Monocytes were refractory to IFN-γ stimulation and showed high levels of a negative regulator of cytokine signalling, suppressor of cytokine signalling-1. MOB was unaffected by 7 days in vivo prednisolone therapy. Conclusions Monocyte oxidative burst and bacterial killing is impaired in alcoholic hepatitis while bacterial uptake by phagocytosis is preserved. Defective MOB is associated with reduced expression of NADPH oxidase in these patients and predicts the development of infection and death

Incidence and outcomes for patients with cirrhosis admitted to the United Kingdom Critical Care Unitsa

OBJECTIVE: To assess the epidemiology and outcome of patients with cirrhosis following critical care unit admission. DESIGN: Retrospective cohort study. SETTING: Critical care units in England, Wales, and Northern Ireland participating in the U.K. Intensive Care National Audit and Research Centre Case Mix Programme. PATIENTS: Thirty-one thousand three hundred sixty-three patients with cirrhosis identified of 1,168,650 total critical care unit admissions (2.7%) admitted to U.K. critical care units between 1998 and 2012. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Ten thousand nine hundred thirty-six patients had alcohol-related liver disease (35%). In total, 1.6% of critical care unit admissions in 1998 had cirrhosis rising to 3.1% in 2012. The crude critical care unit mortality of patients with cirrhosis was 41% in 1998 falling to 31% in 2012 (p < 0.001). Crude hospital mortality fell from 58% to 46% over the study period (p < 0.001). Mean(SD) Acute Physiology and Chronic Health Evaluation II score in 1998 was 20.3 (8.5) and 19.5 (7.1) in 2012. Mean Acute Physiology and Chronic Health Evaluation II score for patients with alcohol-related liver disease in 2012 was 20.6 (7.0) and 19.0 (7.2) for non-alcohol-related liver disease (p < 0.001). In adjusted analysis, alcohol-related liver disease was associated with increased risk of death (odds ratio, 1.51 [95% CI, 1.42-1.62; p < 0.001]) with a year-on-year reduction in hospital mortality (adjusted odds ratio, 0.95/yr, [0.94-0.96, p < 0.001]). CONCLUSIONS: More patients with cirrhosis are being admitted to critical care units but with increasing survival rates. Patients with alcohol-related liver disease have reduced survival rates partly explained by higher levels of organ failure at admission. Patients with cirrhosis and organ failure warrant a trial of organ support and universal prognostic pessimism is not justified