Understanding the mechanism of action of repurposed antihypertensive drugs against Borrelia burgdorferi

/ABSTRACT Borrelia burgdorferi is the cause of over 475,000 cases of Lyme disease annually in the United States. There are currently no preventative measures for Lyme disease beyond tick avoidance. To provide additional means to prevent new Lyme disease cases, this grant aims to identify a narrow spectrum antibiotic that can be used for pre-exposure prophylaxis for Lyme disease. I have previously conducted a high-throughput compound screen and identified four calcium channel blockers (CCB) that inhibit B. burgdorferi growth. These CCBs are from two different classes of CCBs and have different chemical structures. I further showed the CCBs are non-inhibitory in E. coli and S. aureus, suggesting that these compounds act as a narrow-spectrum antimicrobial agent that could be deployed against B. burgdorferi. The objective of this proposal is to identify the mechanism of action in B. burgdorferi of the CCBs identified from my screen. I hypothesize that the calcium channel blockers disrupt calcium and/or divalent cations homeostasis in B. burgdorferi leading to inhibition of growth. First, I will determine if excess divalent cation supplementation is able to overcome the inhibitory action of the CCBs and if the CCBs alter intracellular divalent cation concentrations. B. burgdorferi has two known metal transporters that will be investigated as possible targets of the CCBs. For the second aim, I will use transcriptional and morphological profiling to develop a machine learning multi-modal autoencoder to characterize compound-induced cell death. This model uses a training set of cell responses to known antibiotics and can be used to identify pathways of interest for compounds of unknown mechanisms. This model will be used to identify possible mechanisms of action of the CCBs. With the information from the first and second aim, I will validate possible targets as the mechanism of inhibition of CCBs through qRT-PCR and gene deletion. This proposal aims to characterize CCBs as this class of drugs could be developed into pre-exposure prophylaxis. Additionally, these studies will also develop a computational tool to help in the identification of mechanisms of action of novel compounds. Together, these advances will aid in the development of new pre-exposure methods to prevent Lyme disease, which could prove to be invaluable in disrupting the continuous rise of annual cases in the United States. Project Number: 1F31AI197469-01 | Fiscal Year: 2026 | NIH Institute/Center: National Institute of Allergy and Infectious Diseases (NIAID) | Principal Investigator: Kee-Lee Stocks | Institution: TUFTS UNIVERSITY BOSTON, BOSTON, MA | Award Amount: $46,302 | Activity Code: F31 | Study Section: Special Emphasis Panel[ZRG1 F07A-W (20)] View on NIH RePORTER: https://reporter.nih.gov/project-details/1F31AI19746901