Th1 and Th2 Cytokine Profiles in Ewes with Subclinical Mastitis Caused by Mycoplasma agalactiae and Coagulase-Negative Staphylococci

The present study aimed to evaluate Th1- and Th2-associated cytokine profiles in sheep with subclinical mastitis caused by coagulase-negative staphylococci (CoNS) and Mycoplasma agalactiae (M. agalactiae). The study included 90 Hamdani ewes with subclinical mastitis at mid lactation and without apparent clinical signs. First, the California Mastitis Test (CMT) was performed on each mammary half. Following evaluation of the CMT results, milk samples were collected for microbiological analysis after disinfection of the teat ends. Milk samples that showed no bacterial growth on microbiological analysis and were CMT-negative constituted the control group (n = 30). Milk samples that were CMT-positive and yielded either CoNS (n = 30) or M. agalactiae (n = 30) were assigned to the respective study groups. Samples showing growth of two or more bacterial species were excluded from the study. Following completion of sample collection for the predefined groups, Th1-associated cytokines, including Tumor Necrosis Factor-Alpha (TNF-α), Interferon-gamma (IFN-γ), and Interleukine-2 (IL-2), and Th2-associated cytokines, including IL-4, IL-5, and IL-10, were quantified in the milk samples using the enzyme-linked immunosorbent assay (ELISA) method. ELISA analyses were performed in accordance with the manufacturer’s instructions. Comparative analysis of cytokine concentrations among the groups revealed statistically significant differences in IL-2, IL-4, and IL-10 concentrations. Specifically, IL-2, IL-4, and IL-10 concentrations were significantly higher in the CoNS group than in both the control and M. agalactiae groups. The CoNS group exhibited significantly higher concentrations of IL-2, IL-4, and IL-10 (12.69 ± 0.50, 66.90 ± 2.43, and 52.45 ± 2.14 ng/L, respectively) compared with the control group (7.50 ± 0.31, 54.62 ± 1.71, and 39.60 ± 2.38 ng/L, respectively) and the M. agalactiae group (8.97 ± 0.49, 53.96 ± 2.12, and 42.82 ± 1.83 ng/L, respectively). In contrast, no statistically significant differences were observed among the groups in terms of IFN-γ, TNF-α, and IL-5 concentrations. Overall, these findings suggest that the immune response associated with subclinical mastitis may vary depending on the etiological agent, with distinct cytokine concentration profiles observed between CoNS- and M. agalactiae-associated infections.