Impaired quality of the hepatitis B virus (HBV)-specific T-cell response in human immunodeficiency virus type 1-HBV coinfection

Abstract

Hepatitis B virus (HBV)-specific T cells play a key role both in the control of HBV replication and in the pathogenesis of liver disease. Human immunodeficiency virus type 1 (HIV-1) coinfection and the presence or absence of HBV e (precore) antigen (HBeAg) significantly alter the natural history of chronic HBV infection. We examined the HBV-specific T-cell responses in treatment-naïve HBeAg-positive and HBeAg-negative HIV-1-HBV-coinfected (n = 24) and HBV-monoinfected (n = 39) Asian patients. Peripheral blood was stimulated with an overlapping peptide library for the whole HBV genome, and tumor necrosis factor alpha and gamma interferon cytokine expression in CD8+ T cells was measured by intracellular cytokine staining and flow cytometry. There was no difference in the overall magnitude of the HBV-specific T-cell responses, but the quality of the response was significantly impaired in HIV-1-HBV-coinfected patients compared with monoinfected patients. In coinfected patients, HBV-specific T cells rarely produced more than one cytokine and responded to fewer HBV proteins than in monoinfected patients. Overall, the frequency and quality of the HBV-specific T-cell responses increased with a higher CD4+ T-cell count (P = 0.018 and 0.032, respectively). There was no relationship between circulating HBV-specific T cells and liver damage as measured by activity and fibrosis scores, and the HBV-specific T-cell responses were not significantly different in patients with either HBeAg-positive or HBeAg-negative disease. The quality of the HBV-specific T-cell response is impaired in the setting of HIV-1-HBV coinfection and is related to the CD4+ T-cell count.

FIG. 1.

ICS for HBV-specific T cells. (A) Lymphocytes were selected by forward and side scatter, and data from at least 100,000 small lymphocytes were generally collected. (B) In most samples, data from at least 10,000 to 20,000 CD8⁺ T cells were collected for analysis. The percentage of HBV-specific T cells was defined as the percentage of cytokine-producing CD8⁺ T cells. A positive response was considered to be >0.05% cytokine⁺ CD8⁺ T cells above background (the response to stimulation with dimethyl sulfoxide and costimulatory molecules alone) and also at least twofold above background. (C) Representative positive responses are shown for production of TNF-α and IFN-γ from CD8⁺ T cells in HBV-monoinfected (left) and coinfected (right) individuals.

FIG. 2.

Magnitudes and frequencies of HBV-specific T-cell responses. (A) HBV-specific T-cell responses were measured for both coinfected (open symbols) and HBV-monoinfected (closed symbols) patients, and the magnitude of IFN-γ (triangles) and TNF-α (circles) production by CD8⁺ T cells was quantified. Additionally, HIV-1 Gag-specific T-cell responses were also measured in coinfected patients. The means are represented by the horizontal bars. (B) The percentages of individuals who had a detectable HBV-specific T-cell response are shown for both IFN-γ and TNF-α for coinfected (open bars) and HBV-monoinfected (closed bars) patients. The percentages of coinfected patients who had a detectable HIV-1 Gag-specific T-cell response (hatched bars) are also shown.

FIG. 3.

Specificity of the HBV-specific T-cell response. (A) The mean magnitude of the HBV-specific T-cell responses to each HBV gene (precore/core, surface, X protein, and polymerase) for all coinfected and HBV-monoinfected patients (left graph) and the specificity of the response for HBeAg-positive and HBeAg-negative monoinfected (middle graph) and coinfected (right graph) patients. *, P = 0.006, and **, P = 0.018 for comparisons of the breadth of response in HBeAg-positive coinfected and HBV-monoinfected patients. (B) The mean magnitude of the HBV-specific response for each HBV gene separately.

FIG. 4.

Production of either single or double cytokines from HBV-specific T cells and relationship to the CD4⁺ T-cell count. (A) Percentages of patients with no detectable HBV-specific T-cell response (nonresponders), production of only TNF-α responders, production of only IFN-γ responders, and production of both cytokines detected in the same patient (TNF-α and IFN-γ double responders) for both coinfected and HBV-monoinfected patients. In HBV-monoinfected patients, there were significantly more double-cytokine responders than single-cytokine responders (P < 0.001). (B) CD4⁺ T-cell counts for coinfected individuals who did not generate a detectable response (nonresponders), produced only TNF-α or IFN-γ (single responder), or produced both cytokines (double responder) in HBV-specific T cells. The CD4⁺ T-cell count is also shown for patients who had a detectable HBV-specific IFN-γ⁺ or TNF-α⁺ CD8⁺ T-cell response (produced as either a single or double responder). The horizontal lines in all graphs represent the means.

FIG. 5.

Magnitudes and frequencies of HBV-specific T-cell responses in HBeAg-positive and HB-Ag-negative patients. (A) HBV-specific T-cell responses were measured for HBeAg-positive and HBeAg-negative coinfected (open symbols) and HBV-monoinfected (closed symbols) patients. The magnitudes of IFN-γ (triangles) and TNF-α (circles) production by CD8⁺ T cells were quantified. The means are represented by the horizontal bars. (B) Percentages of individuals who had a detectable IFN-γ and TNF-α HBV-specific T-cell response for HBeAg-positive and HBeAg-negative coinfected and HBV-monoinfected patients.