Unveiling the Th17/Treg imbalance: a key player in Clostridioides difficile-induced infection

Clostridioides difficile infection (CDI) can elicit varying degrees of intestinal inflammation. To investigate the association between CDI and Th17/Treg cell imbalance, fecal DNA was extracted for the specific detection of C. difficile toxins and combined with fecal bacterial culture to identify the presence of CDI. Peripheral blood samples were collected from CDI-positive and CDI-negative patients, and flow cytometry was performed to quantify the proportions of Th17 and Treg cells, as well as to measure the serum levels of IL-17A, IL-23, IL-6, and other cytokines. Moreover, peripheral blood mononuclear cell mRNA was isolated for reverse transcription and real-time PCR analysis to determine the relative expression levels of ROR-γt and Foxp3. Statistical analyses were conducted to evaluate the differences between CDI-positive and CDI-negative groups. The results revealed that CDI-positive patients exhibited an increased proportion of Th17 cells, along with elevated levels of Th17-related cytokines such as IL-23 and IL-17A. Additionally, these patients showed an upregulation in the expression of ROR-γt. a specific transcription factor (TF) for Th17 cells as well as an increased ratio of Th17 and Treg cells. These findings provide phenotypic evidence suggesting that CDI is potentially associated with a dynamic interplay between Th17 and Treg cells, a finding supported by measuring key TFs and proteins. Our experiments examining the effects of TcdA toxin-induced Th17 differentiation in peripheral blood also provide further evidence highlighting the importance of this CDI-triggered immune imbalance via Th17-mediated inflammatory responses.