Molecular characterization of cDNA encoding B. taurus cathelicidin-7 like antibiotic peptide from bone marrow cells of Bubalus bubalis

Transcriptomics and iTRAQ-Proteomics Analyses of Bovine Mammary Tissue with Streptococcus agalactiae-Induced Mastitis

Mastitis is a highly prevalent disease in dairy cows that causes large economic losses. Streptococcus agalactiae is a common contagious pathogen and a major cause of bovine mastitis. The immune response to intramammary infection with S. agalactiae in dairy cows is a very complex biological process. To understand the host immune response to S. agalactiae-induced mastitis, mammary gland of lactating Chinese Holstein cows was challenged with S. agalactiae via nipple tube perfusion. Visual inspection, analysis of milk somatic cell counts, histopathology, and transmission electron microscopy of mammary tissue were performed to confirm S. agalactiae-induced mastitis. Microarray and isobaric tags for relative and absolute quantitation (iTRAQ) were used to compare the transcriptomes and proteomes of healthy and mastitic mammary tissue. Compared with healthy tissue, a total of 129 differentially expressed genes (DEGs, fold change >2, p < 0.05) and 144 differentially expressed proteins (DEPs, fold change >1.2, p < 0.05) were identified in mammary tissue from S. agalactiae-challenged cows. Among the concordant 18 DEGs/DEPs, immunoglobulin M precursor, cathelicidin-7 precursor, integrin alpha-5, and complement C4-A-like isoform X1 were associated with mastitis. Intramammary infection with S. agalactiae triggered a complex host innate immune response that involved complement and coagulation cascades, ECM-receptor interaction, focal adhesion, and phagosome and bacterial invasion of epithelial cells pathways. These results provide candidate genes or proteins for further studies in the context of prevention and targeted treatment of bovine mastitis.

Host defense cathelicidins in cattle: types, production, bioactive functions and potential therapeutic and diagnostic applications

Cathelicidins are a primitive class of host defense peptides and are known for their broad-spectrum antimicrobial activity against bacteria, fungi, and enveloped viruses. These small, cationic, proteolytically-activated peptides are diverse in structure, encompassing a wide range of activities on host immune and inflammatory cell responses. The dual capacity of cathelicidins to directly control infection and regulate host defenses highlights the potential use of these peptides as alternatives to antibiotics and immunomodulators. Cathelicidins are found in many mammalian species; this review focuses on bovine cathelicidins. Eight naturally and two synthetically occurring bovine cathelicidins are described in detail, with a focus on recent advances in their expression, location and biological roles. This review also presents an overview of the bioactive functions of cathelicidins in bovine mastitis, a disease causing economic losses in cattle dairy production. Comparison of the structural, antimicrobial, cytotoxic and mechanistic properties of bovine cathelicidins advances the knowledge needed for the development of these peptides as potential identifiers of infectious diseases (e.g., bovine mastitis) and as novel therapeutic alternatives to antibiotics.

Antimicrobial peptides of buffalo and their role in host defenses

Antimicrobial peptides (AMPs) are highly conserved components of the innate immune system found among all classes of life. Buffalo (Bubalus bubalis), an important livestock for milk and meat production, is known to have a better resistance to many diseases as compared to cattle. They are found to express many AMPs such as defensins, cathelicidins, and hepcidin which play an important role in neutralizing the invading pathogens. Buffalo AMPs exhibit broad-spectrum antimicrobial activity against both Gram-positive and Gram-negative bacteria. Similar to its natural form, synthetic analogs of buffalo AMPs are also antimicrobial against bacteria and even fungus making them a good target for the development of therapeutic antimicrobials. In addition to its antimicrobial effect, AMPs have been demonstrated to have a number of immunomodulatory functions, and their genes are responsive to infections. Further, induction of their gene expression by external factors may help in preventing infectious diseases. This review briefly discusses the AMPs of buffalo identified to date and their possible role in innate immunity.

Diversity, Antimicrobial Action and Structure-Activity Relationship of Buffalo Cathelicidins

Cathelicidins are an ancient class of antimicrobial peptides (AMPs) with broad spectrum bactericidal activities. In this study, we investigated the diversity and biological activity of cathelicidins of buffalo, a species known for its disease resistance. A series of new homologs of cathelicidin4 (CATHL4), which were structurally diverse in their antimicrobial domain, was identified in buffalo. AMPs of newly identified buffalo CATHL4s (buCATHL4s) displayed potent antimicrobial activity against selected Gram positive (G+) and Gram negative (G-) bacteria. These peptides were prompt to disrupt the membrane integrity of bacteria and induced specific changes such as blebing, budding, and pore like structure formation on bacterial membrane. The peptides assumed different secondary structure conformations in aqueous and membrane-mimicking environments. Simulation studies suggested that the amphipathic design of buCATHL4 was crucial for water permeation following membrane disruption. A great diversity, broad-spectrum antimicrobial action, and ability to induce an inflammatory response indicated the pleiotropic role of cathelicidins in innate immunity of buffalo. This study suggests short buffalo cathelicidin peptides with potent bactericidal properties and low cytotoxicity have potential translational applications for the development of novel antibiotics and antimicrobial peptidomimetics.