The role of obesity and plasma adipocytokines in immune dysregulation in sepsis patients.

ABSTRACT

INTRODUCTION: The dysregulated immune response in sepsis is highly variable, ranging from hyperinflammation to immunoparalysis. Obesity is associated with the release of inflammatory mediators from adipose tissue, known as adipocytokines, causing a chronic inflammatory state. Perhaps counterintuitively, obesity is also associated with lower mortality in sepsis patients. We investigated the association between obesity, circulating adipocytokine concentrations, immune dysregulation, and outcome in sepsis patients. METHODS: In this secondary analysis of a prospective study, plasma concentrations of the adipocytokines leptin, adiponectin, and resistin were assessed in 167 patients at diagnosis of sepsis due to pneumonia, bacteremia, or acute cholangitis. Adipocytokines were compared between patients with normal weight (BMI 18.5-24.9 kg/m2; n = 67), overweight (BMI 25.0-29.9 kg/m2; n = 56), and obesity (BMI ≥30 kg/m2; n = 42), as well as between immunological endotypes hyperinflammation (n = 40), immunoparalysis (n = 62), and unclassified (n = 55). RESULTS: Higher circulating concentrations of leptin were observed in patients with obesity compared to patients with normal weight (P = 0.008) and overweight (P = 0.02), whereas adiponectin and resistin plasma concentrations were not different (P = 0.08 and P = 0.85, respectively). Resistin concentrations were associated with immunological endotypes, with the highest levels found in hyperinflammatory patients (P < 0.001). Furthermore, resistin concentrations were predictive for 28-day mortality (adjusted OR = 1.03 per 10 ng/mL, P = 0.04). These associations were not found for leptin and adiponectin. CONCLUSIONS: Obesity and BMI-related adipocytokines are not related to the development of a hyperactive or suppressed immune response as defined by ferritin and mHLA-DR expression in sepsis patients. While resistin is related to the immune response and an increased risk of adverse clinical outcomes, these associations are similar in patients with normal weight, overweight, and obesity. This implies that the relationship between resistin and clinical outcome is likely driven by the inflammatory response and not by obesity itself. Taken together, although there exists a strong association between inflammation and sepsis mortality, our results do not point towards a role for obesity and BMI-related adipocytokines in immune dysregulation in sepsis patients.