Baral Pilot Project Summary

Carbapenem-resistant Klebsiella pneumoniae (CRKP) causes respiratory infections and fatal pneumonia, of which minimal treatment options are available. It is responsible for 20-40% of mortality among hospitalized patients. Therefore, alternative treatment options are highly needed. The respiratory tract is densely innervated by nociceptive sensory neurons that mediate pain production and release of neuropeptide calcitonin gene-related peptide (CGRP) in the lungs. I previously found that nociceptive neurons and CGRP from vagus nerves suppress the host defense to Staphylococcus aureus pneumonia by inhibiting CXCL1 production, neutrophil recruitment, and γδ T cell responses. Kaplan and colleagues demonstrated the host protective role of nociceptive neurons and CGRP against Candida albicans infection. However, we do not yet understand the role of nociceptive neurons and CGRP in host responses to CRKP pneumonia. The overall objective of this project is to perform large-scale screening of small molecules having anti-CGRP impacts on macrophages with effects to protect the mice from CRKP pneumonia. The long-term objectives of this proposal are to develop chemical inhibitors of the CGRP signaling pathway as therapeutics to treat Gram-negative pneumonia. CGRP acts on its cognate heterodimer receptor complex (Ramp1-Calcrl) expressed by immune cells for immunomodulation. Our preliminary data demonstrate the inhibitory effects of CGRP signaling on the immune responses to CRKP infections. Thus, the central hypothesis of this proposal is that chemical inhibition of CGRP-mediated immunomodulation will promote immunity to CRKP infections. To test the central hypothesis, the following specific aims will be pursued. Aim 1 is to use in vivo CRKP lung infection, lung immunology, and bacteriology to define the role of CGRP-Ramp1/Calcrl signaling in fatal CRKP pneumonia. Aim 2 is to collaborate with the CBID IDAD Core at the University of Kansas to perform a high-throughput screen to identify chemical inhibitors of CGRP-mediated immune suppression in macrophages. Identified most promising compounds will be evaluated for their ability to control CRKP lung infection in mice. Thus, this work will provide a foundation for the use of chemical biology to study immune modulating signaling pathways and the development of chemical inhibitors that enhance our immune system to combat Gram-negative infection. The proposed research will also provide the generation of preliminary data sufficient for a successful NIH R01 application.