Gaining knowledge about the calgranulins S100A8/A9 and S100A12 in saliva of cows: changes in parturition and lameness

Salivary biomarkers are emerging as valuable, non-invasive tools in the field of bovine medicine. The calgranulins S100A8/A9 and S100A12 are major neutrophil-derived proteins reflecting innate immune activation. This study aimed to develop and validate a new immunoassay for S100A12 measurements and evaluate the dynamics of both calgranulins in cow saliva under physiological (peripartum) and pathological (lameness) conditions. An AlphaLISA immunoassay for S100A12 was developed and analytically validated, demonstrating high precision (intra- and inter-assay coefficients of variation (CVs) <15%), accuracy (mean recovery, 101.8%; linearity under dilution,R² > 0.98) and high sensitivity (LLQ = 0.03 mg/L). Then, salivary concentrations of S100A12 and S100A8/A9 were measured in multiparous Holstein-Friesian cows around parturition (n = 48 samples) and in lame versus healthy cows (n = 24 samples). Both proteins exhibited significant increases at calving compared to pre- and postpartum values (p < 0.05) and were positively correlated with inflammatory biomarkers (haptoglobin and adenosine deaminase). S100A12 also was negatively correlated with antioxidants (CUPRAC, FRAP and TEAC). In lame cows, S100A12 and S100A8/A9 increased 2.4- and 3.25-fold respectively, compared with healthy controls (p < 0.05). Strong correlations were observed between S100A8/A9 and S100A12 in both conditions. These findings suggest that salivary S100A12 and S100A8/A9 are potential indicators of general inflammatory activation, being S100A12 also associated with oxidative stress. Overall, this supports further investigation to elucidate their potential as non-invasive biomarkers for assessing the health and welfare of dairy cows.