PLoS Pathogens (Jan 2013)

Maintenance of intestinal Th17 cells and reduced microbial translocation in SIV-infected rhesus macaques treated with interleukin (IL)-21.

  • Suresh Pallikkuth,
  • Luca Micci,
  • Zachary S Ende,
  • Robin I Iriele,
  • Barbara Cervasi,
  • Benton Lawson,
  • Colleen S McGary,
  • Kenneth A Rogers,
  • James G Else,
  • Guido Silvestri,
  • Kirk Easley,
  • Jacob D Estes,
  • Francois Villinger,
  • Savita Pahwa,
  • Mirko Paiardini

DOI
https://doi.org/10.1371/journal.ppat.1003471
Journal volume & issue
Vol. 9, no. 7
p. e1003471

Abstract

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In pathogenic HIV and SIV infections of humans and rhesus macaques (RMs), preferential depletion of CD4⁺ Th17 cells correlates with mucosal immune dysfunction and disease progression. Interleukin (IL)-21 promotes differentiation of Th17 cells, long-term maintenance of functional CD8⁺ T cells, and differentiation of memory B cells and antibody-secreting plasma cells. We hypothesized that administration of IL-21 will improve mucosal function in the context of pathogenic HIV/SIV infections. To test this hypothesis, we infected 12 RMs with SIV(mac239) and at day 14 post-infection treated six of them with rhesus rIL-21-IgFc. IL-21-treatment was safe and did not increase plasma viral load or systemic immune activation. Compared to untreated animals, IL-21-treated RMs showed (i) higher expression of perforin and granzyme B in total and SIV-specific CD8⁺ T cells and (ii) higher levels of intestinal Th17 cells. Remarkably, increased levels of Th17 cells were associated with reduced levels of intestinal T cell proliferation, microbial translocation and systemic activation/inflammation in the chronic infection. In conclusion, IL-21-treatment in SIV-infected RMs improved mucosal immune function through enhanced preservation of Th17 cells. Further preclinical studies of IL-21 may be warranted to test its potential use during chronic infection in conjunction with antiretroviral therapy.