OCLN and mastitis: We found that clinical mastitis cows had significantly higher mRNA levels of interleukin-1β (IL-1β) and interleukin-6 (IL-6) and markedly lower expression of tight junction (TJ) genes (nectin cell adhesion molecule 4 [NECTIN4], tight junction protein 1 [ZO-1], occludin) in mammary tissue and milk somatic cells compared to healthy controls.