Extracellular traps released by antimicrobial TH17 cells contribute to host defense
George W. Agak, Alice Mouton, Rosane M.B. Teles, Thomas Weston, Marco Morselli, Priscila R. Andrade, Matteo Pellegrini, Robert L. Modlin
George W. Agak, Alice Mouton, Rosane M.B. Teles, Thomas Weston, Marco Morselli, Priscila R. Andrade, Matteo Pellegrini, Robert L. Modlin
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Research Article Immunology

Extracellular traps released by antimicrobial TH17 cells contribute to host defense

Abstract

TH17 cell subpopulations have been defined that contribute to inflammation and homeostasis, yet the characteristics of TH17 cells that contribute to host defense against infection are not clear. To elucidate the antimicrobial machinery of the TH17 subset, we studied the response to Cutibacterium acnes, a skin commensal that is resistant to IL-26, the only known TH17-secreted protein with direct antimicrobial activity. We generated C. acnes–specific antimicrobial TH17 clones (AMTH17) with varying antimicrobial activity against C. acnes, which we correlated by RNA sequencing to the expression of transcripts encoding proteins that contribute to antimicrobial activity. Additionally, we validated that AMTH17-mediated killing of C. acnes and bacterial pathogens was dependent on the secretion of granulysin, granzyme B, perforin, and histone H2B. We found that AMTH17 cells can release fibrous structures composed of DNA decorated with histone H2B that entangle C. acnes that we call T cell extracellular traps (TETs). Within acne lesions, H2B and IL-17 colocalized in CD4+ T cells, in proximity to TETs in the extracellular space composed of DNA decorated with H2B. This study identifies a functionally distinct subpopulation of TH17 cells with an ability to form TETs containing secreted antimicrobial proteins that capture and kill bacteria.

Authors

George W. Agak, Alice Mouton, Rosane M.B. Teles, Thomas Weston, Marco Morselli, Priscila R. Andrade, Matteo Pellegrini, Robert L. Modlin

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Figure 5

Histone H2B is a component of AMTH17 antimicrobial activity.

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Histone H2B is a component of AMTH17 antimicrobial activity. (A) Superna...
(A) Supernatants derived from activated AMTH17 clone S26 were incubated with α-granulysin neutralizing antibody or control IgG for 1 hour prior and used in CFU assay against C. acnes strain HL005PA1. Data are shown as mean ± SEM (n > 3). ****P < 0.0001 by repeated-measures 1-way ANOVA for treatment groups compared with C. acnes control. (B–E) Correlation plots of HIST2H2BE gene expression in AMTH17, as determined in RNA-seq against CFU assays and ELISA protein secretion after 6 hours (B and C) and 12 hours (D and E). P values by Student’s t test (n = 20). (F) Observed CFU activity against C. acnes strain HLA110PA3 after 4-hour incubation with recombinant histones H2B and H4 and heat-inactivated controls. Data are representative of 4 independent experiments. ****P < 0.0001 by repeated-measures 1-way ANOVA for treatment groups compared with C. acnes control. (G) Supernatants derived from activated AMTH17 clone S26 were incubated with α-H2B neutralizing antibody or control IgG for 1 hour prior and used in CFU assay against E. coli. Data are representative of 3 independent experiments. ****P < 0.0001 by repeated-measures 1-way ANOVA for treatment groups compared with E. coli control. (H) S. aureus after 24-hour incubation with recombinant histones H2B and H4. Data show average CFU from 3 independent experiments. ****P < 0.0001 by repeated-measures 1-way ANOVA for treatment groups compared with S. aureus control.