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Cytotoxic capacity of SIV-specific CD8(+) T cells against primary autologous targets correlates with immune control in SIV-infected rhesus macaques.

Mendoza D, Migueles SA, Rood JE, Peterson B, Johnson S, Doria-Rose N, Schneider D, Rakasz E, Trivett MT, Trubey CM, Coalter V, Hallahan CW, Watkins D, Franchini G, Lifson JD, Connors M - PLoS Pathog. (2013)

Bottom Line: Although the study of non-human primates has resulted in important advances for understanding HIV-specific immunity, a clear correlate of immune control over simian immunodeficiency virus (SIV) replication has not been found to date.In addition, significant correlations between ICE and viral load (r = -0.57, p = 0.01), and between granzyme B delivery and ICE (r = 0.89, p<0.001) were observed.These findings support that greater lytic granule loading of virus-specific CD8(+) T cells and efficient delivery of active granzyme B to SIV-infected targets are associated with superior control of SIV infection in rhesus macaques, consistent with observations of HIV infection in humans.

View Article: PubMed Central - PubMed

Affiliation: HIV-Specific Immunity Section, Laboratory of Immunoregulation, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, United States of America.

ABSTRACT
Although the study of non-human primates has resulted in important advances for understanding HIV-specific immunity, a clear correlate of immune control over simian immunodeficiency virus (SIV) replication has not been found to date. In this study, CD8(+) T-cell cytotoxic capacity was examined to determine whether this function is a correlate of immune control in the rhesus macaque (RM) SIV infection model as has been suggested in chronic HIV infection. SIVmac251-infected human reverse transcriptase (hTERT)-transduced CD4(+) T-cell clone targets were co-incubated with autologous macaque effector cells to measure infected CD4(+) T-cell elimination (ICE). Twenty-three SIV-infected rhesus macaques with widely varying plasma viral RNA levels were evaluated in a blinded fashion. Nineteen of 23 subjects (83%) were correctly classified as long-term nonprogressor/elite controller (LTNP/EC), slow progressor, progressor or SIV-negative rhesus macaques based on measurements of ICE (weighted Kappa 0.75). LTNP/EC had higher median ICE than progressors (67.3% [22.0-91.7%] vs. 23.7% [0.0-58.0%], p = 0.002). In addition, significant correlations between ICE and viral load (r = -0.57, p = 0.01), and between granzyme B delivery and ICE (r = 0.89, p<0.001) were observed. Furthermore, the CD8(+) T cells of LTNP/EC exhibited higher per-cell cytotoxic capacity than those of progressors (p = 0.004). These findings support that greater lytic granule loading of virus-specific CD8(+) T cells and efficient delivery of active granzyme B to SIV-infected targets are associated with superior control of SIV infection in rhesus macaques, consistent with observations of HIV infection in humans. Therefore, such measurements appear to represent a correlate of control of viral replication in chronic SIV infection and their role as predictors of immunologic control in the vaccine setting should be evaluated.

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SIV-specific CD8+ T cells of LTNP/EC mediate greater per-cell killing of SIV-infected targets than those of progressors, which is not simply due to higher true E∶T ratios.A. The true effector to target (E∶T) ratios, determined by measurements of IFN-γ-secreting CD8+ T-cell effectors and p27-expressing CD4+ T-cell targets, respectively, as described in the Methods and shown in the Figure S1 and Table S1, were compared between LTNP/EC (n = 11) and progressors (n = 11). Horizontal bars represent the median values. B, C. GrB target cell activity (B) or ICE (C) responses plotted against the true E∶T ratios are shown for LTNP/EC (n = 10, GrB target cell activity; n = 11, ICE) and progressors (n = 11). GrB target cell activity is shown after subtraction of background. The response curves were analyzed by regressing ICE and GrB on log true E∶T ratios using analysis of covariance. The standard two-tailed t test from regression analysis was used to compare estimated GrB target cell activity and ICE of LTNP/EC with that of progressors at the 5.8 E∶T ratio, the median of the combined E∶T ranges of both groups.
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ppat-1003195-g004: SIV-specific CD8+ T cells of LTNP/EC mediate greater per-cell killing of SIV-infected targets than those of progressors, which is not simply due to higher true E∶T ratios.A. The true effector to target (E∶T) ratios, determined by measurements of IFN-γ-secreting CD8+ T-cell effectors and p27-expressing CD4+ T-cell targets, respectively, as described in the Methods and shown in the Figure S1 and Table S1, were compared between LTNP/EC (n = 11) and progressors (n = 11). Horizontal bars represent the median values. B, C. GrB target cell activity (B) or ICE (C) responses plotted against the true E∶T ratios are shown for LTNP/EC (n = 10, GrB target cell activity; n = 11, ICE) and progressors (n = 11). GrB target cell activity is shown after subtraction of background. The response curves were analyzed by regressing ICE and GrB on log true E∶T ratios using analysis of covariance. The standard two-tailed t test from regression analysis was used to compare estimated GrB target cell activity and ICE of LTNP/EC with that of progressors at the 5.8 E∶T ratio, the median of the combined E∶T ranges of both groups.

Mentions: In order to determine whether the diminished cytotoxic responses of progressors relative to LTNP/EC were merely due to lower CD8+ T-cell numbers following 6 days of stimulation or also reflected reduced per-cell cytotoxic capacity, we analyzed the SIV-specific responses over the range of true effector-to-target (E∶T) ratios based on the percentage of IFN-γ-secreting effectors and p27-expressing targets (Figure S1, Table S1 and Figure 4) [12]–[14]. Although the true median E∶T ratios determined by these measurements were not significantly different between LTNP/EC and progressor macaques (10.9% [2.6–13.3%] versus 4.1% [0.0–11.0%], respectively, p = 0.06; Figure 4A), a trend towards higher E∶T ratios was observed among LTNP/EC, which is likely due to their known increased CD8+ T-cell proliferative capacity. To further assess whether differences in per-cell cytotoxic capacity also existed between LTNP/EC and progressors, killing curves representing the trends for each group were generated by plotting the cytotoxic responses against these true E∶T ratios. Differences between the killing curves were then quantified by regression analysis and analysis of covariance at the median log E∶T ratio. Non-overlapping curves would support the existence of differences in per-cell cytotoxic capacity (in addition to differences in cell numbers), whereas overlapping curves would support the low cytotoxicity of progressor CD8+ T cells was primarily due to fewer cell numbers following expansion since per-cell cytotoxic capacity was similar to that of LTNP/EC. The capacity of CD8+ T cells of LTNP/EC to deliver active GrB to infected targets on a per-cell basis was not significantly different from that of progressors at the median E∶T ratio of 5.8 (39% versus 25%, p = 0.14; Figure 4B). However, LTNP/EC-derived CD8+ T cells displayed significantly higher ICE on a per-cell basis than did those of progressors at the median E∶T ratio of 5.8 (57% versus 26%, p = 0.004; Figure 4C). Notably, the cytotoxic responses of progressors measured by either parameter plateaued at low E∶T ratios and did not increase significantly even at high E∶T ratios, suggestive of limited per-cell cytotoxic capacity. This is in marked contrast to the responses of LTNP/EC (Figures 4B and C). In summary, these results indicate that CD8+ T cells of LTNP/EC possess greater SIV-specific cytotoxic capacity on a per-cell basis than those of progressors and that changes in both the numbers of virus-specific CD8+ T cells and in their per-cell cytotoxic capacity following re-stimulation with SIV-infected targets are required for maximal cytotoxicity, as had been observed in human HIV infection [12]–[14].


Cytotoxic capacity of SIV-specific CD8(+) T cells against primary autologous targets correlates with immune control in SIV-infected rhesus macaques.

Mendoza D, Migueles SA, Rood JE, Peterson B, Johnson S, Doria-Rose N, Schneider D, Rakasz E, Trivett MT, Trubey CM, Coalter V, Hallahan CW, Watkins D, Franchini G, Lifson JD, Connors M - PLoS Pathog. (2013)

SIV-specific CD8+ T cells of LTNP/EC mediate greater per-cell killing of SIV-infected targets than those of progressors, which is not simply due to higher true E∶T ratios.A. The true effector to target (E∶T) ratios, determined by measurements of IFN-γ-secreting CD8+ T-cell effectors and p27-expressing CD4+ T-cell targets, respectively, as described in the Methods and shown in the Figure S1 and Table S1, were compared between LTNP/EC (n = 11) and progressors (n = 11). Horizontal bars represent the median values. B, C. GrB target cell activity (B) or ICE (C) responses plotted against the true E∶T ratios are shown for LTNP/EC (n = 10, GrB target cell activity; n = 11, ICE) and progressors (n = 11). GrB target cell activity is shown after subtraction of background. The response curves were analyzed by regressing ICE and GrB on log true E∶T ratios using analysis of covariance. The standard two-tailed t test from regression analysis was used to compare estimated GrB target cell activity and ICE of LTNP/EC with that of progressors at the 5.8 E∶T ratio, the median of the combined E∶T ranges of both groups.
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Related In: Results  -  Collection

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ppat-1003195-g004: SIV-specific CD8+ T cells of LTNP/EC mediate greater per-cell killing of SIV-infected targets than those of progressors, which is not simply due to higher true E∶T ratios.A. The true effector to target (E∶T) ratios, determined by measurements of IFN-γ-secreting CD8+ T-cell effectors and p27-expressing CD4+ T-cell targets, respectively, as described in the Methods and shown in the Figure S1 and Table S1, were compared between LTNP/EC (n = 11) and progressors (n = 11). Horizontal bars represent the median values. B, C. GrB target cell activity (B) or ICE (C) responses plotted against the true E∶T ratios are shown for LTNP/EC (n = 10, GrB target cell activity; n = 11, ICE) and progressors (n = 11). GrB target cell activity is shown after subtraction of background. The response curves were analyzed by regressing ICE and GrB on log true E∶T ratios using analysis of covariance. The standard two-tailed t test from regression analysis was used to compare estimated GrB target cell activity and ICE of LTNP/EC with that of progressors at the 5.8 E∶T ratio, the median of the combined E∶T ranges of both groups.
Mentions: In order to determine whether the diminished cytotoxic responses of progressors relative to LTNP/EC were merely due to lower CD8+ T-cell numbers following 6 days of stimulation or also reflected reduced per-cell cytotoxic capacity, we analyzed the SIV-specific responses over the range of true effector-to-target (E∶T) ratios based on the percentage of IFN-γ-secreting effectors and p27-expressing targets (Figure S1, Table S1 and Figure 4) [12]–[14]. Although the true median E∶T ratios determined by these measurements were not significantly different between LTNP/EC and progressor macaques (10.9% [2.6–13.3%] versus 4.1% [0.0–11.0%], respectively, p = 0.06; Figure 4A), a trend towards higher E∶T ratios was observed among LTNP/EC, which is likely due to their known increased CD8+ T-cell proliferative capacity. To further assess whether differences in per-cell cytotoxic capacity also existed between LTNP/EC and progressors, killing curves representing the trends for each group were generated by plotting the cytotoxic responses against these true E∶T ratios. Differences between the killing curves were then quantified by regression analysis and analysis of covariance at the median log E∶T ratio. Non-overlapping curves would support the existence of differences in per-cell cytotoxic capacity (in addition to differences in cell numbers), whereas overlapping curves would support the low cytotoxicity of progressor CD8+ T cells was primarily due to fewer cell numbers following expansion since per-cell cytotoxic capacity was similar to that of LTNP/EC. The capacity of CD8+ T cells of LTNP/EC to deliver active GrB to infected targets on a per-cell basis was not significantly different from that of progressors at the median E∶T ratio of 5.8 (39% versus 25%, p = 0.14; Figure 4B). However, LTNP/EC-derived CD8+ T cells displayed significantly higher ICE on a per-cell basis than did those of progressors at the median E∶T ratio of 5.8 (57% versus 26%, p = 0.004; Figure 4C). Notably, the cytotoxic responses of progressors measured by either parameter plateaued at low E∶T ratios and did not increase significantly even at high E∶T ratios, suggestive of limited per-cell cytotoxic capacity. This is in marked contrast to the responses of LTNP/EC (Figures 4B and C). In summary, these results indicate that CD8+ T cells of LTNP/EC possess greater SIV-specific cytotoxic capacity on a per-cell basis than those of progressors and that changes in both the numbers of virus-specific CD8+ T cells and in their per-cell cytotoxic capacity following re-stimulation with SIV-infected targets are required for maximal cytotoxicity, as had been observed in human HIV infection [12]–[14].

Bottom Line: Although the study of non-human primates has resulted in important advances for understanding HIV-specific immunity, a clear correlate of immune control over simian immunodeficiency virus (SIV) replication has not been found to date.In addition, significant correlations between ICE and viral load (r = -0.57, p = 0.01), and between granzyme B delivery and ICE (r = 0.89, p<0.001) were observed.These findings support that greater lytic granule loading of virus-specific CD8(+) T cells and efficient delivery of active granzyme B to SIV-infected targets are associated with superior control of SIV infection in rhesus macaques, consistent with observations of HIV infection in humans.

View Article: PubMed Central - PubMed

Affiliation: HIV-Specific Immunity Section, Laboratory of Immunoregulation, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, United States of America.

ABSTRACT
Although the study of non-human primates has resulted in important advances for understanding HIV-specific immunity, a clear correlate of immune control over simian immunodeficiency virus (SIV) replication has not been found to date. In this study, CD8(+) T-cell cytotoxic capacity was examined to determine whether this function is a correlate of immune control in the rhesus macaque (RM) SIV infection model as has been suggested in chronic HIV infection. SIVmac251-infected human reverse transcriptase (hTERT)-transduced CD4(+) T-cell clone targets were co-incubated with autologous macaque effector cells to measure infected CD4(+) T-cell elimination (ICE). Twenty-three SIV-infected rhesus macaques with widely varying plasma viral RNA levels were evaluated in a blinded fashion. Nineteen of 23 subjects (83%) were correctly classified as long-term nonprogressor/elite controller (LTNP/EC), slow progressor, progressor or SIV-negative rhesus macaques based on measurements of ICE (weighted Kappa 0.75). LTNP/EC had higher median ICE than progressors (67.3% [22.0-91.7%] vs. 23.7% [0.0-58.0%], p = 0.002). In addition, significant correlations between ICE and viral load (r = -0.57, p = 0.01), and between granzyme B delivery and ICE (r = 0.89, p<0.001) were observed. Furthermore, the CD8(+) T cells of LTNP/EC exhibited higher per-cell cytotoxic capacity than those of progressors (p = 0.004). These findings support that greater lytic granule loading of virus-specific CD8(+) T cells and efficient delivery of active granzyme B to SIV-infected targets are associated with superior control of SIV infection in rhesus macaques, consistent with observations of HIV infection in humans. Therefore, such measurements appear to represent a correlate of control of viral replication in chronic SIV infection and their role as predictors of immunologic control in the vaccine setting should be evaluated.

Show MeSH
Related in: MedlinePlus