Autophagy links antimicrobial activity with antigen presentation in Langerhans cells
Angeline Tilly Dang, Rosane M.B. Teles, Phillip T. Liu, Aaron Choi, Annalisa Legaspi, Euzenir N. Sarno, Maria T. Ochoa, Kislay Parvatiyar, Genhong Cheng, Michel Gilliet, Barry R. Bloom, Robert L. Modlin
Angeline Tilly Dang, Rosane M.B. Teles, Phillip T. Liu, Aaron Choi, Annalisa Legaspi, Euzenir N. Sarno, Maria T. Ochoa, Kislay Parvatiyar, Genhong Cheng, Michel Gilliet, Barry R. Bloom, Robert L. Modlin
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Research Article Immunology Infectious disease

Autophagy links antimicrobial activity with antigen presentation in Langerhans cells

Abstract

DC, through the uptake, processing, and presentation of antigen, are responsible for activation of T cell responses to defend the host against infection, yet it is not known if they can directly kill invading bacteria. Here, we studied in human leprosy, how Langerhans cells (LC), specialized DC, contribute to host defense against bacterial infection. IFN-γ treatment of LC isolated from human epidermis and infected with Mycobacterium leprae (M. leprae) activated an antimicrobial activity, which was dependent on the upregulation of the antimicrobial peptide cathelicidin and induction of autophagy. IFN-γ induction of autophagy promoted fusion of phagosomes containing M. leprae with lysosomes and the delivery of cathelicidin to the intracellular compartment containing the pathogen. Autophagy enhanced the ability of M. leprae–infected LC to present antigen to CD1a-restricted T cells. The frequency of IFN-γ labeling and LC containing both cathelicidin and autophagic vesicles was greater in the self-healing lesions vs. progressive lesions, thus correlating with the effectiveness of host defense against the pathogen. These data indicate that autophagy links the ability of DC to kill and degrade an invading pathogen, ensuring cell survival from the infection while facilitating presentation of microbial antigens to resident T cells.

Authors

Angeline Tilly Dang, Rosane M.B. Teles, Phillip T. Liu, Aaron Choi, Annalisa Legaspi, Euzenir N. Sarno, Maria T. Ochoa, Kislay Parvatiyar, Genhong Cheng, Michel Gilliet, Barry R. Bloom, Robert L. Modlin

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Figure 6

Autophagy is essential for antimicrobial response.

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Autophagy is essential for antimicrobial response. (A) LCDC were culture...
(A) LCDC were cultured with rIFN-γ, with pretreatment of wortmannin (WM) or DMSO (MED) and immunolabeled with anti-LC3 antibody (green). Nuclei were stained with DAPI (blue). Representative shown of 4 independent experiments. Images captured on a 63× lens, with 6× zoom. (B) The number of LC3 puncta per cell were quantified. Data are represented as mean puncta per cell ± SEM, n ≥ 30 cells. (C) LCDC were stimulated with rIFN-γ, with pretreatment of WM or DMSO, and infected with M. leprae with a MOI of 10; they were stimulated with rIFN-γ, with treatment of WM or DMSO for an additional 4 days. Viability of mLEP was detected by qPCR, and percent increase or decrease relative to media was determined. Data are represented as mean ± SEM, n = 5. (D) LCDC were transfected with siRNA oligos for ATG5 (siATG5) or nonspecific (siCtrl) and then treated with rIFN-γ, followed by M. leprae infection overnight, and transfected with siRNAs and rIFN-γ. Viability of mLEP was calculated as in C. Data are represented as mean ± SEM, n = 4. (E) Primary CD1a+ LC were stimulated with rIFN-γ and washed and infected with S. aureus at a MOI of 3. Data are represented as mean ± SEM, n = 4. (F) LCDC were stimulated with rIFN-γ, with pretreatment of WM or DMSO for 4 hours, and infected with S. aureus (left) or S. pyogenes (right) at a MOI of 3. Data are represented as mean ± SEM, n = 5. (G) LCDC were stimulated with rIFN-γ, with pretreatment of WM or DMSO, and infected with C. albicans at a MOI of 3. Viability was quantified by CFU assay for E–G. Data are represented as mean SEM, n = 5. *P < 0.05, **P < 0.01. Repeated measures 1-way ANOVA.