Antimicrobial peptides (AMPs) are the arsenals of the innate host defense system, exhibiting evolutionarily conserved characteristics that are present in practically all forms of life. Recent years have witnessed the emergence of antibiotic-resistant bacteria compounded with a slow discovery rate for new antibiotics that have necessitated scientific efforts to search for alternatives to antibiotics. Research on the identification of AMPs has generated very encouraging evidence that they curb infectious pathologies and are also useful as novel biologics to function as immunotherapeutic agents. Being innate, they exhibit the least cytotoxicity to the host and exerts a wide spectrum of biological activity including low resistance among microbes and increased wound healing actions. Notably, in veterinary science, the constant practice of massive doses of antibiotics with inappropriate withdrawal programs led to a high risk of livestock-associated antimicrobial resistance. Therefore, the world faces tremendous pressure for designing and devising strategies to mitigate the use of antibiotics in animals and keep it safe for posterity. In this review, we illustrate the diversity of farm animal-specific AMPs, and their biochemical foundations, mode of action, and prospective application in clinics. Subsequently, we present the data for their systematic classification under the major and minor groups, antipathogenic action, and allied bioactivities in the host. Finally, we address the limitations of their clinical implementation and envision areas for further advancement.

Hydrogen sulfide is a gaseous, reactive molecule specifically enriched in the gastrointestinal tract. Here, we uncover a non-redundant role for sulfide in the control of both microbial and immune homeostasis of the gut. Notably, depletion of sulfide via both pharmaceutical and dietary interventions led to a profound collapse of CD4 T cells in the ileum of the small intestine lamina propria and significant impact on microbial ecology. As a result, mice with reduced sulfide within the gut were deficient in their ability to mount T cell dependent antibody responses to oral vaccine. Mechanistically, our results support the idea that sulfide could act directly on CD4 T cells via enhanced AP-1 activation, leading to heightened proliferation and cytokine production. This study uncovers sulfides as keystone components in gut ecology and provides mechanistic insight between diet, gut sulfide production and mucosal immunity.