Up-Regulation of S100A8 and S100A9 in Pulmonary Immune Response Induced by a Mycoplasma capricolum subsp. capricolum HN-B Strain.

Simple Summary: Mycoplasma capricolum subsp. capricolum (Mcc) is an important pathogen associated with diseases in goats, hindering the development of the livestock industry. We previously isolated the HN-B strain of Mcc from goats on Hainan Island, China. The genomic and biological characteristics of this strain were investigated. In this study, we infected mice and RAW264.7 cells with Mcc HN-B to explore its pathogenic mechanism in the host. Differentially expressed genes related to immune terms and pathways were identified using bioinformatic analyses. The expression of two inflammatory proteins, S100A8 and S100A9, was up-regulated in mouse lungs post Mcc HN-B infection. This study preliminarily elucidates the pathogenesis of Mcc in mice and paves the way for further research in goats. Mycoplasma capricolum subsp. capricolum (Mcc), a member of the Mycoplasma mycoides cluster, has a negative impact on the goat-breeding industry. However, little is known about the pathogenic mechanism of Mcc. This study infected mice using a previously isolated strain, Mcc HN-B. Hematoxylin and eosin staining, RNA sequencing, bioinformatic analyses, RT-qPCR, and immunohistochemistry were performed on mouse lung tissues. The results showed that 235 differentially expressed genes (DEGs) were identified. GO and KEGG enrichment analyses suggested that the DEGs were mainly associated with immune response, defensive response to bacteria, NF-kappa B signaling pathway, natural killer cell-mediated cytotoxicity, and T cell receptor signaling pathway. RT-qPCR verified the expression of Ccl5, Cd4, Cd28, Il2rb, Lck, Lat, Ptgs2, S100a8, S100a9, and Il-33. The up-regulation of S100A8 and S100A9 at the protein level was confirmed by immunohistochemistry. Moreover, RT-qPCR assays on Mcc HN-B-infected RAW264.7 cells also showed that the expression of S100a8 and S100a9 was elevated. S100A8 and S100A9 not only have diagnostic value in Mcc infection but also hold great significance in clarifying the pathogenic mechanism of Mcc. This study preliminarily elucidates the mechanism of Mcc HN-B-induced lung injury and provides a theoretical basis for further research on Mcc–host interactions. [ABSTRACT FROM AUTHOR]