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PACAP is a pathogen-inducible resident antimicrobial neuropeptide affording rapid and contextual molecular host defense of the brain

Lee, Ernest Y. and Chan, Liana C. and Wang, Huiyuan and Lieng, Juelline and Hung, Mandy and Srinivasan, Yashes and Wang, Jennifer and Waschek, James A. and Ferguson, Andrew L. and Lee, Kuo-Fen and Yount, Nannette Y. and Yeaman, Michael R. and Wong, Gerard C. L. (2021) PACAP is a pathogen-inducible resident antimicrobial neuropeptide affording rapid and contextual molecular host defense of the brain. Proceedings of the National Academy of Sciences of the United States of America, 118 (1). Art. No. e1917623117. ISSN 0027-8424.

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Defense of the central nervous system (CNS) against infection must be accomplished without generation of potentially injurious immune cell-mediated or off-target inflammation which could impair key functions. As the CNS is an immune-privileged compartment, inducible innate defense mechanisms endogenous to the CNS likely play an essential role in this regard. Pituitary adenylate cyclase-activating polypeptide (PACAP) is a neuropeptide known to regulate neurodevelopment, emotion, and certain stress responses. While PACAP is known to interact with the immune system, its significance in direct defense of brain or other tissues is not established. Here, we show that our machine-learning classifier can screen for immune activity in neuropeptides, and correctly identified PACAP as an antimicrobial neuropeptide in agreement with previous experimental work. Furthermore, synchrotron X-ray scattering, antimicrobial assays, and mechanistic fingerprinting provided precise insights into how PACAP exerts antimicrobial activities vs. pathogens via multiple and synergistic mechanisms, including dysregulation of membrane integrity and energetics and activation of cell death pathways. Importantly, resident PACAP is selectively induced up to 50-fold in the brain in mouse models of Staphylococcus aureus or Candida albicans infection in vivo, without inducing immune cell infiltration. We show differential PACAP induction even in various tissues outside the CNS, and how these observed patterns of induction are consistent with the antimicrobial efficacy of PACAP measured in conditions simulating specific physiologic contexts of those tissues. Phylogenetic analysis of PACAP revealed close conservation of predicted antimicrobial properties spanning primitive invertebrates to modern mammals. Together, these findings substantiate our hypothesis that PACAP is an ancient neuro-endocrine-immune effector that defends the CNS against infection while minimizing potentially injurious neuroinflammation.

Item Type:Article
Related URLs:
URLURL TypeDescription Information
Lee, Ernest Y.0000-0001-5144-2552
Chan, Liana C.0000-0003-2567-4418
Wang, Huiyuan0000-0002-4911-6990
Srinivasan, Yashes0000-0002-5279-9753
Wang, Jennifer0000-0001-5238-7989
Waschek, James A.0000-0003-2727-9876
Ferguson, Andrew L.0000-0002-8829-9726
Lee, Kuo-Fen0000-0003-2224-2708
Yount, Nannette Y.0000-0002-7079-5211
Yeaman, Michael R.0000-0002-9468-5252
Wong, Gerard C. L.0000-0003-0893-6383
Additional Information:© 2020 National Academy of Sciences. Published under the PNAS license. Edited by Lawrence Steinman, Stanford University School of Medicine, Stanford, CA, and approved October 12, 2020 (received for review August 4, 2020). We thank Ling Wang and Hong-Kyu Lee, M.S. for their efforts in antimicrobial assessment of PACAP. E.Y.L. acknowledges support from the Systems and Integrative Biology Training Program (NIH T32GM008185), the Medical Scientist Training Program (NIH T32GM008042), and the Dermatology Scientist Training Program (NIH T32AR071307) at the University of California, Los Angeles. E.Y.L. also acknowledges an Early Career Research Grant from the National Psoriasis Foundation. G.C.L.W. is supported by NIH R01AI143730, NIH R01AI052453, NSF DMR1808459, and the National Psoriasis Foundation (20194384). M.R.Y. acknowledges grant support from the National Institute of Allergy and Infectious Diseases (NIAID) AI-124319 and AI-111661. K.-F.L. is supported by grants from the NIH (OD023076, MH114831, NS115183, AG054714, AG062232, and AG064049), a grant to the Salk core facility (CA014195), the Clayton Foundation and the Freeburg Foundation, and by funding from the Helen McLoraine Chair. X-ray research was conducted at Stanford Synchrotron Radiation Lightsource, SLAC National Laboratory, supported by the US Department of Energy (DOE) Office of Basic Energy Sciences under Contract DE-AC02-76SF00515. The Stanford Synchrotron Radiation Laboratory Structural Molecular Biology Program is supported by the DOE Office of Biological and Environmental Research and by the NIH, National Institute of General Medical Sciences (including P41GM103393). Data Availability: All study data are included in the paper and SI Appendix. M.R.Y. and G.C.L.W. contributed equally to this work. Author contributions: E.Y.L., A.L.F., K.-F.L., N.Y.Y., M.R.Y., and G.C.L.W. designed research; E.Y.L., L.C.C., H.W., J.L., M.H., Y.S., and J.A.W. performed research; E.Y.L., L.C.C., H.W., J.A.W., A.L.F., K.-F.L., N.Y.Y., M.R.Y., and G.C.L.W. contributed new reagents/analytic tools; E.Y.L., L.C.C., H.W., N.Y.Y., M.R.Y., and G.C.L.W. analyzed data; and E.Y.L., A.L.F., K.-F.L., N.Y.Y., M.R.Y., and G.C.L.W. wrote the paper. Competing interest statement: M.R.Y is founder and shareholder of NovaDigm Therapeutics, Inc., which pursues novel antiinfective agents and strategies; he holds patents in the area of antimicrobial peptides and related molecules. This article is a PNAS Direct Submission. We have run the SVM classifier on the PACAP metabolite identified here and found it to be antimicrobial but with a different score than the parent PACAP peptide, which is consistent with the findings of the authors. This article contains supporting information online at
Funding AgencyGrant Number
NIH Predoctoral FellowshipT32GM008185
NIH Predoctoral FellowshipT32GM008042
NIH Predoctoral FellowshipT32AR071307
National Psoriasis Foundation20194384
Clayton FoundationUNSPECIFIED
Freeburg FoundationUNSPECIFIED
Helen McLoraine ChairUNSPECIFIED
Department of Energy (DOE)DE-AC02-76SF00515
Subject Keywords:neuropeptides; innate immunity; antimicrobial peptides; neuroimmunology; host defense
Issue or Number:1
Record Number:CaltechAUTHORS:20210106-150327667
Persistent URL:
Official Citation:PACAP is a pathogen-inducible resident antimicrobial neuropeptide affording rapid and contextual molecular host defense of the brain. Ernest Y. Lee, Liana C. Chan, Huiyuan Wang, Juelline Lieng, Mandy Hung, Yashes Srinivasan, Jennifer Wang, James A. Waschek, Andrew L. Ferguson, Kuo-Fen Lee, Nannette Y. Yount, Michael R. Yeaman, Gerard C. L. Wong. Proceedings of the National Academy of Sciences Jan 2021, 118 (1) e1917623117; DOI: 10.1073/pnas.1917623117
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:107354
Deposited By: Tony Diaz
Deposited On:06 Jan 2021 23:28
Last Modified:06 Jan 2021 23:28

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