Abstract
HIV/SIV (simian immunodeficiency virus) infection leads to a loss of CD4+ T helper (Th) cells in number and function that begins during the acute phase and persists through the chronic phase of infection. In particular, there is a drastic decrease of Th17 and Th22 cells in the HIV/SIV-infected gastrointestinal (GI) tract as a source of interleukin (IL)-17 and IL-22. These cytokines are vital in the immune response to extracellular pathogens and maintenance of the GI tract. However, innate lymphoid cells (ILCs) are a source of IL-17 and IL-22 during the early stages of an immune response in mucosal tissue and remain vital cytokine producers when the immune response is persistent. Here, we wanted to determine whether ILCs are a source of IL-17 and IL-22 in the SIV-infected colon and could compensate for the loss of Th17 and Th22 cells. As a control, we evaluated the frequency and number of ILCs expressing interferon-gamma (IFNγ) and tumor necrosis factor-alpha (TNFα). We determined the frequency and number of cytokine expressing ILC subsets and T cell subsets within leukocytes from the colons of uninfected as well as acute and chronic SIV-infected colons without in vitro mitogenic stimulation. In the present study, we find that: (1) the frequency of IL-22, IFNγ, and TNFα but not IL-17 producing ILCs is increased in the acutely infected colon and remains high during the chronically infected colon relative to cytokine expressing ILCs in the uninfected colon, (2) ILCs are a significant source of IL-22, IFNγ, and TNFα but not IL-17 when CD4+ T lymphocytes in the gut lose their capacity to secrete these cytokines during SIV infection, and (3) the changes in the cytokines expressed by ILCs relative to CD4+ T cells in the infected colon were not due to increases in the frequency or number of ILCs in relation to T lymphocytes found in the tissue.
Get full access to this article
View all access options for this article.
References
Supplementary Material
Please find the following supplemental material available below.
For Open Access articles published under a Creative Commons License, all supplemental material carries the same license as the article it is associated with.
For non-Open Access articles published, all supplemental material carries a non-exclusive license, and permission requests for re-use of supplemental material or any part of supplemental material shall be sent directly to the copyright owner as specified in the copyright notice associated with the article.
