Evaluation of Intestinal Barrier Biomarkers and Glucagon-like Peptide-2 in SIRS-Positive and SIRS-Negative Diarrheic Calves

This study investigated circulating tight junction (TJ) proteins (Zonula Occludens-1 [ZO-1], Occludin, Claudin-3) and Glucagon-Like Peptide-2 (GLP-2) concentrations across varying clinical severities of neonatal calf diarrhea. Thirty-six calves—categorized by Systemic Inflammatory Response Syndrome (SIRS) criteria into SIRS-positive (n = 12), SIRS-negative (n = 11), and healthy control (n = 13) groups—were evaluated via ELISA. In SIRS-negative calves, serum ZO-1 levels were significantly lower than in healthy controls (p = 0.0276) and positively correlated with leukocyte counts (r = 0.64). Conversely, SIRS-positive calves exhibited significantly higher GLP-2 levels compared with SIRS-negative calves (p = 0.0040), whereas serum ZO-1 levels did not differ significantly from healthy controls. Significant positive correlations (|r| > 0.50, p < 0.05) were identified between GLP-2 and TJ proteins within the SIRS-positive cohort. In conclusion, circulating GLP-2 and ZO-1 may serve as potential candidate biomarkers for monitoring intestinal barrier profiles and clinical severity in diarrheic calves, though further validation in larger prospective cohorts is warranted.