Synthetic cathelicidin LL-37 reduces Mycobacterium avium subsp. paratuberculosis internalization and pro-inflammatory cytokines in macrophages

Karina M. Cirone, Priyoshi Lahiri, Ravi Holani, Yi Lin Tan, Rakel Arrazuria, Jeroen De Buck, Herman W. Barkema, Eduardo R. Cobo

Research output: Contribution to journalArticle


Mycobacterium avium subsp. paratuberculosis (MAP) causes chronic diarrheic intestinal infections in domestic and wild ruminants (paratuberculosis or Johne’s disease) for which there is no effective treatment. Critical in the pathogenesis of MAP infection is the invasion and survival into macrophages, immune cells with ability to carry on phagocytosis of microbes. In a search for effective therapeutics, our objective was to determine whether human cathelicidin LL-37, a small peptide secreted by leuckocytes and epithelial cells, enhances the macrophage ability to clear MAP infection. In murine (J774A.1) macrophages, MAP was quickly internalized, as determined by confocal microscopy using green fluorescence protein expressing MAPs. Macrophages infected with MAP had increased transcriptional gene expression of pro-inflammatory TNF-α, IFN-γ, and IL-1β cytokines and the leukocyte chemoattractant IL-8. Pretreatment of macrophages with synthetic LL-37 reduced MAP load and diminished the transcriptional expression of TNF-α and IFN-γ whereas increased IL-8. Synthetic LL-37 also reduced the gene expression of Toll-like receptor (TLR)-2, key for mycobacterial invasion into macrophages. We concluded that cathelicidin LL-37 enhances MAP clearance into macrophages and suppressed production of tissue-damaging inflammatory cytokines. This cathelicidin peptide could represent a foundational molecule to develop therapeutics for controlling MAP infection.

Original languageEnglish (US)
Pages (from-to)207-217
Number of pages11
JournalCell and Tissue Research
Issue number1
StatePublished - Jan 1 2020
Externally publishedYes



  • Cathelicidin
  • IL-8
  • LL-37
  • Macrophages
  • Mycobacterium avium subsp. paratuberculosis

ASJC Scopus subject areas

  • Pathology and Forensic Medicine
  • Histology
  • Cell Biology

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