# “Bifidobacterium longum-reactive T helper cells as marker for intestinal barrier impairment in ICU patients with sepsis”

## TL;DR

The study identifies Bifidobacterium longum-reactive T helper cells in blood as a marker for intestinal barrier dysfunction in ICU patients with sepsis.

## Contribution

A novel sepsis-specific T-helper cell signature is identified as a potential biomarker for intestinal barrier impairment.

## Key findings

- A sepsis-specific T-helper cell signature was identified in peripheral blood using ARTE and flow cytometry.
- The signature is characterized by expanded Bifidobacterium longum-reactive T-helper cells, indicating intestinal barrier dysfunction.
- This method allows monitoring of intestinal barrier function and therapeutic effects using blood samples.

## Abstract

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.

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.

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.