Epigenetic mechanisms during pathogen-specific mastitis of the cow

• Applicants: Dr. Juliane Günther; Privatdozent Dr. Wolfram Petzl
• Subject Area: Veterinary Medical Science
• Term: from 2014 to 2019
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 251480024

Inflammation of the udder (mastitis) is the major disease of dairy cattle. The Escherichia coli caused mastitis proceeds ordinarily with acute symptoms while Staphylococcus aureus causes subclinical and chronic infections. These are economically and socially most relevant, since their cure requires application of antibiotics, unsuccessful though in ~40% of the cases. Significant efforts have been made during the last years to uncover the pathogen-specific regulatory mechanisms of mastitis pathogenesis at the molecular level. They had mainly been focused on the documentation of modulated gene expression profiles of the host subsequent to pathogen contact and on the known classical mechanisms inducing gene transcription. However, involvement and significance of epigenetic mechanisms for the regulation of immune functions in the udder have not been analyzed to date albeit their pivotal function has meanwhile been well documented for a wide variety of diseases. Acetylation and methylation of histone H3 are crucial mediators of epigenetic regulation. This project therefore aims in the first place to globally document modulation of the histone H3 code during host-pathogen interaction in udder, as well as in model cells. Modulations caused by E. coli will be compared to those as elicited by S. aureus. The respective histone H3 variants will be precipitated with specific antibodies (chromatin-immuno-precipitation; ChIP). The adhering DNA fragments will globally be characterized (ChIP-Seq technique) and also regarding selected relevant candidate genes. The significance of these modifications will be validated in model cells through the application of specific inhibitors of enzymes known to modifying that histone code. Building upon previous reports, it will be analysed regarding the chronic S. aureus mastitis, if intra-mammary application of the know histone-modulator vitamin D3 will reduce the duration of a chronic mastitis, thus promising to reducing the risk of chronic infections. Comprehensive clinical recording will document the physiology of a chronic S, aureus mastitis in infected control animals and the respective efficacy of the vitamin D3 treatment will be analyzed. The underpinning mechanisms of vitamin D3 action (modulation of histone signatures, expression of candidate factors, modulation of immune cell function) will be analyzed in detail, both in vivo (udder samples, milk cells, blood) and in vitro (model cells). This first time uncovering of epigenetic mechanisms operating during the pathogen-specific defence in the udder will provide new molecular foundations for the understanding of immune-physiological regulations in the udder. The results might open new perspectives for innovative concepts for prophylaxis and therapy of mastitis and chronic mastitis, in particular.

• DFG Programme: Research Grants
• Participating Persons: Professor Dr. Hans-Martin Seyfert; Professor Dr. Holm Zerbe