Mice lacking the antimicrobial peptide CRAMP (the mouse equivalent of human LL-37) developed extensive skin warts after papillomavirus infection, showing that cathelicidins protect against HPV primarily through immune modulation rather than direct antiviral action.
First in vivo HPV protectionCRAMP is the first cathelicidin antimicrobial peptide shown to protect against papillomavirus infection in a living animal model
What the researchers found
CRAMP-deficient mice developed robust skin papillomas after papillomavirus infection while wild-type mice did not. Protection was primarily immune-mediated: CRAMP-deficient mice showed reduced CD4+ and CD8+ T cells and lacked virus-specific neutralizing antibodies.
Why it matters
This is the first in vivo evidence that cathelicidin antimicrobial peptides protect against papillomavirus infection, primarily by enhancing immune responses. This could inform new prevention or treatment strategies for HPV-related diseases in humans.
The numbers in context
Robust papillomas in CRAMP-deficient mice; none in wild-type; reduced CD4+ and CD8+ T cells; no neutralizing antibodies without CRAMP
How the study worked
Animal study. CRAMP-deficient and wild-type C57BL/6J mice were treated with cyclosporine A and experimentally infected with mouse papillomavirus 1. Papilloma development, immune cell counts, neutralizing antibody levels, and direct antiviral effects of synthetic CRAMP were analyzed.
Who was studied
CRAMP-deficient and wild-type C57BL/6J mice with cyclosporine A treatment
What this study cannot tell us
Mouse model with cyclosporine A immunosuppression, which may amplify cathelicidin's protective role. Mouse papillomavirus differs from human HPV. CRAMP is not identical to human LL-37. Sample size not reported.
How to read the evidence
Moderate evidence: controlled animal study demonstrating a clear mechanism, but uses an immunosuppressed mouse model and mouse papillomavirus rather than human HPV.
When this study was published
Published in 2021. Research on cathelicidins and viral defense continues with increasing interest in their immune-modulatory roles.
The bigger picture
LL-37/cathelicidins are increasingly recognized as immune regulators beyond simple antimicrobial agents. This study adds HPV defense to their repertoire and suggests that maintaining cathelicidin levels could be relevant for people at risk of HPV-related conditions.
Questions still open
- Could LL-37 supplementation or upregulation help prevent or treat HPV infections in humans?
- Do people with naturally lower LL-37 levels have higher susceptibility to persistent HPV infections?
- Would topical cathelicidin application be effective against skin or genital warts?
Common questions
What is CRAMP and how does it relate to LL-37?
Could this help with HPV treatment in humans?
Read the original research
Deficiency of Cathelicidin-related Antimicrobial Peptide Promotes Skin Papillomatosis in Mus musculus Papillomavirus 1-infected Mice.
Acta dermato-venereologica, 101(1), adv00367
Citation
Dorfer, Sonja; Strasser, Katharina; Reipert, Siegfried; Fischer, Michael B; Shafti-Keramat, Saeed; Bonelli, Michael; Schröckenfuchs, Georg; Bauer, Wolfgang; Kancz, Stefanie; Müller, Lena; Handisurya, Alessandra. (2021). Deficiency of Cathelicidin-related Antimicrobial Peptide Promotes Skin Papillomatosis in Mus musculus Papillomavirus 1-infected Mice.. Acta dermato-venereologica, 101(1), adv00367. https://doi.org/10.2340/00015555-3733