Abstract
BACKGROUND: Critical illness often leads to the development of intestinal dysbiosis, which can have a significant impact on disease outcome. Intestinal barrier dysfunction is a common problem in intensive care unit patients, particularly those with sepsis. Despite its importance, early and reliable diagnosis of barrier dysfunction and evaluation of therapeutic options remain lacking in clinical practice. Given that intestinal hyperpermeability is associated with increased translocation of luminal antigens and subsequent priming of naïve T cells, we hypothesized that analysis of circulating peripheral antigen-reactive T cells could provide insight into the functionality of the intestinal barrier. RESULTS: To test this hypothesis, 70 ICU patients were enrolled, including those with sepsis, those not meeting sepsis criteria, and COVID-19 patients, as well as 20 healthy volunteers. We identified a sepsis-specific T-helper cell signature in peripheral blood using the antigen-reactive T-cell enrichment (ARTE) technique followed by flow cytometric analysis. This signature was characterized by an expansion of gut trophic Bifidobacterium longum-reactive T-helper cells, indicating significant intestinal barrier dysfunction during sepsis. CONCLUSION: This approach allows the study of intestinal barrier functionality and provides a means to monitor the effects of potential therapeutic interventions over time using blood samples.