Daily Sepsis Research Analysis

Sepsis remains a major clinical challenge, with high mortality and long-term disability despite current interventions. Here, we identify the tissue hormone acyl-CoA-binding protein (ACBP), also known as diazepam-binding inhibitor (DBI), as a biomarker and driver of poor outcome in sepsis. ACBP/DBI was elevated in the plasma of septic patients and associated with organ dysfunction and increased mortality. In murine models of endotoxemia, Escherichia coli infection, and polymicrobial sepsis, genetic deletion or antibody-mediated neutralization of ACBP/DBI conferred robust protection by dampening cytokine storm and preserving organ function. Across these three models, neutralization of ACBP/DBI with monoclonal antibodies restored thermoregulation and reduced mortality. Mechanistically, ACBP/DBI inhibition enhanced resilience to lipopolysaccharide-induced sterile inflammation and improved bacterial clearance by macrophages and granulocytes in vivo and in vitro. These effects were observed in monomicrobial infection models and confirmed by high-dimensional immunophenotyping in a polymicrobial sepsis model. Notably, ACBP/DBI inhibition could be favorably combined with glucocorticoids, enhancing survival and reversing histopathological, transcriptional or metabolic signatures of septic shock across heart, kidney, liver, lung, spleen and plasma. These findings position ACBP/DBI as a mechanistic amplifier of sepsis pathophysiology and propose its neutralization, alone or in combination with corticosteroids, as a promising therapeutic strategy to interrupt the fatal trajectory of septic shock.

Sepsis is a dysregulated host response to infection and a leading cause of global mortality, yet effective targeted therapies remain lacking. Here, we applied a proteogenomic framework integrating large-scale human genetics with circulating proteomics to identify therapeutic targets. In a meta-analysis of genome-wide association studies of 60,314 sepsis cases and 1,464,733 controls, we identified four genome-wide significant loci, including a missense variant in SERPINA1, encoding alpha-1 antitrypsin (AAT), that was also associated with 30-day sepsis mortality in the UK Biobank. Mendelian randomization (MR) and colocalization analyses supported a causal and protective effect of higher genetically predicted circulating AAT levels on sepsis risk. The protective association was highly specific to acute infectious phenotypes, including pneumonia, and was not observed for non-infectious traits. In two independent cohorts (UK Genomic Advances in Sepsis and the Biobanque Québécois sur la COVID-19), circulating AAT increased markedly during acute illness but was significantly attenuated among missense variant carriers in a dose-dependent manner, consistent with impaired protease-antiprotease balance. MR of the AAT-regulated proteome recapitulated findings from prior sepsis trials, both negative and positive, providing orthogonal genetic support for therapeutic modulation of this pathway. Together, these findings provide the first human genetic evidence for AAT's causal role in sepsis, positioning SERPINA1 as a high-priority candidate for drug repurposing and targeted therapeutic interventions.

Hypocholesterolemia hallmarks sepsis, though its pathophysiology and tissue-specific consequences are unclear. As low circulating cholesterol may reflect impaired endogenous cholesterol synthesis, we hypothesized that infusion of the cholesterol precursor mevalonate can reverse sepsis-induced hypocholesterolemia, whereby beneficially affecting adrenal and muscle integrity. In a catheterized mouse model of cecal-ligation and puncture-induced sepsis (male 24-week-old C57BL/6J mice), septic mice received either 5-day mevalonate infusion (78 mg/d) or placebo, versus healthy controls (n=50). Plasma HDL-, LDL-cholesterol, corticosterone, total bile acids, and adrenocortical lipids, myofiber cholesterol and muscle force were quantified. Expression markers of cholesterol homeostasis and structural integrity were investigated in adrenal, muscle and liver tissue. Liver mevalonate metabolites were quantified with LC-MS. Next, a secondary analysis on a prospective observational human study on the time course of adrenal function in the ICU was performed to assess the association between plasma cholesterol and cortisol (n=47). Also, plasma mevalonate was quantified with LC-MS. In septic mice, 5-day mevalonate infusion worsened HDL- and LDL-hypocholesterolemia versus placebo (P<0.05). Decreased hepatic cholesterol synthesis expression markers, apolipoproteins and hepatic cholesterol concentrations were observed in mevalonate-infused septic mice versus placebo (P<0.05). No additional effect on plasma corticosterone, bile acids, myofiber cholesterol, and loss of muscle force and adrenocortical lipid depletion was observed. In prolonged sepsis patients, plasma mevalonate was increased, whereas plasma HDL- and LDL-cholesterol were low (P<0.05), but did not correlate with plasma cortisol. To conclude, mevalonate infusion worsened sepsis-induced hypocholesterolemia, possibly due to increased feedback on hepatic cholesterol synthesis, without aggravating the adrenal or muscle sepsis phenotype.