Th2 cell hyporesponsiveness during chronic murine schistosomiasis is cell intrinsic and linked to GRAIL expression
Justin J. Taylor, Connie M. Krawczyk, Markus Mohrs, Edward J. Pearce
Justin J. Taylor, Connie M. Krawczyk, Markus Mohrs, Edward J. Pearce
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Research Article Infectious disease

Th2 cell hyporesponsiveness during chronic murine schistosomiasis is cell intrinsic and linked to GRAIL expression

Abstract

Chronic infections are associated with progressively declining T cell function. Infections with helminth parasites, such as Schistosoma mansoni, are often chronic and characterized by the development of strong Th2 responses that peak during the acute stage of infection and then decline despite ongoing infection; this minimizes Th2-dependent immunopathology during the chronic stage of infection. We sought to understand the basis for the decline in Th2 responses in chronic schistosomiasis. Using IL-4 reporter mice (mice that express EGFP as a reporter for Il4 gene expression) to identify Th2 cells, we found that Th2 cell numbers plateaued during acute infection and remained constant thereafter. However, the percentages of Th2 cells proliferating during late infection were strikingly lower than those during acute infection. Th2 cell hyporesponsiveness was evident within 10 d of initiation of the Th2 response and became progressively ingrained thereafter, in response to repeated Ag stimulation. Gene expression analyses implicated the E3-ubiquitin ligase gene related to anergy in lymphocytes (GRAIL) in the hyporesponsive state. Consistent with this, suppression of GRAIL expression using retrovirally delivered siRNA prevented the development of hyporesponsiveness induced by repeated Ag stimulation in vitro or in vivo. Together, these data indicate that the decline in Th2 cell responsiveness during chronic schistosomiasis is the net result of the upregulation of GRAIL expression in response to repeated Ag stimulation.

Authors

Justin J. Taylor, Connie M. Krawczyk, Markus Mohrs, Edward J. Pearce

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Figure 4

Th2 hyporesponsiveness does not rely on the ligation of inhibitory receptors.

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Th2 hyporesponsiveness does not rely on the ligation of inhibitory recep...
(A) Gated CD4+ splenocytes from infected and control mice were analyzed for the expression of PD-1, surface CTLA-4, intracellular (IC) CTLA-4, LAG-3, BTLA-4, CD5, and IL-4/GFP by flow cytometry. Plots shown and quadrant statistics are from representative animals (3–4 mice per group). For all plots but CD5, numbers within plots indicate percent cells in the respective quadrants, and bold numbers indicate mean percent IL-4/GFP+ cells expressing the marker. For CD5, numbers above plots indicate mean MFI. (B and C) Sorted GFP+CD4+ and GFP–CD4+ cells from naive mice or mice infected with S. mansoni for 8 wk or 16 wk were restimulated in vitro with plate-bound anti-CD3 alone or with anti-CD28 for 72 h. Control mice received no antibody. (B) Cytokine concentrations in culture supernatants were measured by ELISA. Error bars denote SD of 3 measurements per group. (C) Proliferation was assessed using flow cytometry to determine the incorporation of BrdU during the 72-h culture period. Numbers within histograms indicate percent BrdU+ cells. (D) Gated CD4+ splenocytes from infected and control mice were analyzed for the expression of CD3ε and IL-4/GFP by flow cytometry. Plots are from representative animals. Numbers within plots indicate mean CD3ε MFI within IL-4/GFP+ and IL-4/GFP– cells (3–4 mice per group).