Selective antimicrobial peptides from milk for bacterial vaginosis

项目摘要

Project Abstract Several currently administered antibiotics raise two main concerns: resistance and non-selectivity. The rapid rate of emerging multi-drug resistance poses a global health threat and dramatically increases economic burden. With traditional antibiotics being largely non-selective, there are serious side effects due to the natural host microbiome being modified, and thus a loss in homeostasis. The strong need for innovative, potent, naturally occurring and specifically selective therapeutics have prompted us to explore for such bioactive molecules in milk. The result of 200 million years of evolutionary pressure, mammalian lactation guides the development of the infant and provides protection from a wide-variety of infections. Upon fractionating thousands of naturally occurring peptides from human milk, and discovering their antibacterial activity, we have focused on the function and mechanism of action of novel antimicrobial peptides from human milk. One such peptide, HBCA2, an internal 12-mer sequence of human b-casein rapidly eliminates the viability of gram-positive and gram-negative bacteria, including but not limited to Category 1 priority pathogens. We have made the key observation that Gardnerella vaginalis, a major bacterial vaginosis (BV)-associated pathogen, is susceptible to HBCA2, whereas the viability of key lactobacilli linked to a healthy vaginal microbiome remains unaltered. BV remains an unmet need, with few treatment options and high rates of recurrence resulting in several public health concerns for women of reproductive age. It is associated with outcomes including to not limited to pre-term labor, STI and HIV transmissions, and other reproductive challenges. We propose HBCA2, a milk-borne, antimicrobial peptide, with its unique selectivity feature of inertness towards commensal bacteria, as a lead candidate molecule in topical applications for the treatment of BV—a therapy that could in turn reduce the burden of BV outcomes. In this phase I SBIR grant, we will evaluate a larger range of G. vaginalis strains other bacterial vaginosis associated bacteria as well as a larger number of vaginal and probiotic lactobacilli for their response to HBCA2 and variants of HBCA2 synthesized to enhance efficacy. Additionally, we will determine the HBCA2 mechanism of action, examine its efficacy and/or synergy to traditional antimicrobials, characterize resistance mutations (if any), analyze the direct effect of HBCA2 on mammalian host cells and determine the impact of function on infection and inflammation in pre- clinical infection models of the female reproductive tract. This work will aid the preparation for Phase II, where we will test HBCA2 in in vivo efficacy and early safety PK studies, and determine cervicovaginal tissue impact and immune response. Ultimately, this proposal will allow us to further characterize HBCA2 alone or in combination with additional such peptides as potent antibacterial therapeutic, derived from milk, which can be employed for treatment of recurrent BV via topical applications.