Unmasking Unique Immune Altering Aspects of the Microbiome as a Tool to Correct Sepsis-Induced Immune Dysfunction.

Sepsis-related mortality is driven by immune dysfunction. A bidirectional micro-organism-immune cell cross talks exists. Gut -T-cell crosstalk maintains innate immune cell/pathogen homeostasis. Commensal gut spp. suppress inflammation and induce gut tolerance. Probiotics are administered to restore immune microbiome homeostasis. Individual microbial components have an immunomodulatory effect. However, probiotic therapies for sepsis-induced immune disruptions are rarely tailored to specific immune responses. Thus, we ask the question as to how components of the intestinal microbiome, often found in probiotic therapies, affect lymphocyte phenotypic profile? T-lymphocytes were cultured with either monomicrobial or polymicrobial combinations. Microbes used were , , or . Cytokines, measured by enzyme-linked immunosorbent assay (ELISA)-included interleukin (IL)-6, IL-10, IL-22, and IL-33. Flow cytometry was used for T-cell phenotyping for program-death receptor-1 (PD-1) and B- and T-lymphocyte attenuator (BTLA). T-cell DNA was extracted to assess global epigenetic changes. For translation, IL-33 was measured from surgical intensive care unit (ICU) patients with sepsis with either monomicrobial or polymicrobial infection. consistently induced IL-22 and IL-33. induced IL-33 only under polymicrobial (pB) conditions. Within surgical ICU patients, IL-33 levels were higher in polymicrobial versus monomicrobial patients. PD-1 expression was lowest with either monomicrobial or predominant polymicrobial context. Conversely exposure induced a distinct PD-1 subpopulation. B- and T-lymphocyte attenuator-positive expression did not differ after individual microbes. Among polymicrobial conditions, predominant (pB) and predominant (pL) increased BTLA expression. DNA methylation was most increased in response to in monomicrobial and in response to in polymicrobial conditions. Unique microbe/lymphocyte interactions occur. induced a T-cell phenotype consistent with potential long-term immune recovery. This work begins to discover how varying microbes may induce unique functional and phenotypic T-lymphocyte responses.