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Antigen load and viral sequence diversification determine the functional profile of HIV-1-specific CD8+ T cells.

Streeck H, Brumme ZL, Anastario M, Cohen KW, Jolin JS, Meier A, Brumme CJ, Rosenberg ES, Alter G, Allen TM, Walker BD, Altfeld M - PLoS Med. (2008)

Bottom Line: Virus-specific CD8(+) T lymphocytes play a key role in the initial reduction of peak viremia during acute viral infections, but display signs of increasing dysfunction and exhaustion under conditions of chronic antigen persistence.This exhausted phenotype significantly decreased upon removal of stimulation by antigen, either in response to antiretroviral therapy or by reduction of epitope-specific antigen load in the presence of ongoing viral replication, as a consequence of in vivo selection of cytotoxic T lymphocyte escape mutations in the respective epitopes.Monofunctionality increased in CD8(+) T cell responses directed against conserved epitopes from 49% (95% confidence interval 27%-72%) to 76% (56%-95%) (standard deviation [SD] of the effect size 0.71), while monofunctionality remained stable or slightly decreased for responses directed against escaped epitopes from 61% (47%-75%) to 56% (42%-70%) (SD of the effect size 0.18) (p < 0.05).

View Article: PubMed Central - PubMed

Affiliation: Partners AIDS Research Center, Infectious Disease Unit, Massachusetts General Hospital and Division of AIDS, Harvard Medical School, Boston, Massachusetts, United States of America.

ABSTRACT

Background: Virus-specific CD8(+) T lymphocytes play a key role in the initial reduction of peak viremia during acute viral infections, but display signs of increasing dysfunction and exhaustion under conditions of chronic antigen persistence. It has been suggested that virus-specific CD8(+) T cells with a "polyfunctional" profile, defined by the capacity to secrete multiple cytokines or chemokines, are most competent in controlling viral replication in chronic HIV-1 infection. We used HIV-1 infection as a model of chronic persistent viral infection to investigate the process of exhaustion and dysfunction of virus-specific CD8(+) T cell responses on the single-epitope level over time, starting in primary HIV-1 infection.

Methods and findings: We longitudinally analyzed the polyfunctional epitope-specific CD8(+) T cell responses of 18 patients during primary HIV-1 infection before and after therapy initiation or sequence variation in the targeted epitope. Epitope-specific CD8(+) T cells responded with multiple effector functions to antigenic stimulation during primary HIV-1 infection, but lost their polyfunctional capacity in response to antigen and up-regulated programmed death 1 (PD-1) expression with persistent viremic infection. This exhausted phenotype significantly decreased upon removal of stimulation by antigen, either in response to antiretroviral therapy or by reduction of epitope-specific antigen load in the presence of ongoing viral replication, as a consequence of in vivo selection of cytotoxic T lymphocyte escape mutations in the respective epitopes. Monofunctionality increased in CD8(+) T cell responses directed against conserved epitopes from 49% (95% confidence interval 27%-72%) to 76% (56%-95%) (standard deviation [SD] of the effect size 0.71), while monofunctionality remained stable or slightly decreased for responses directed against escaped epitopes from 61% (47%-75%) to 56% (42%-70%) (SD of the effect size 0.18) (p < 0.05).

Conclusion: These data suggest that persistence of antigen can be the cause, rather than the consequence, of the functional impairment of virus-specific T cell responses observed during chronic HIV-1 infection, and underscore the importance of evaluating autologous viral sequences in studies aimed at investigating the relationship between virus-specific immunity and associated pathogenesis.

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Loss of Epitope-Specific CD8+ T Cell Functionality during Antigen Persistence(A) Summary of fractions of epitope-specific CD8+ T cell responses with one, two, three, four, and five antigen-specific functions in 11 untreated patients (nRx); (B) summary of fractions of eight epitope-specific CD8+ T cell responses for seven patients before and after receiving antiretroviral therapy (Rx). Frequencies of different combination of epitope-specific CD8+ T cell functions were quantified with Boolean gates using FlowJo software, and fractions were calculated from total epitope-specific CD8+ T cell response. Each of the combination of epitope-specific functions (1–5) is shown separately before (“early”) and after (“late”) antiretroviral treatment initiation for the treated study group (Rx) or for a corresponding early and late time point in the untreated group (nRx), respectively. The monofunctional fraction of the HIV-1–specific CD8+ T cell response increased significantly (p < 0.05) in comparison to a decrease of the monofunctional fraction of the HIV-1–specific CD8+ T cell response in the treated group (*). In addition, the increase of the four-functional fraction of the HIV-1–specific CD8+ T cell responses in the treated group was significant (p < 0.05) in comparison to the decrease of the four-functional fraction in the untreated group (*). We used the general linear model to test two-way interaction effects between observation period and group (nRx versus Rx) to calculate significance, and standard errors of the estimate were adjusted for clustering by patient.
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pmed-0050100-g002: Loss of Epitope-Specific CD8+ T Cell Functionality during Antigen Persistence(A) Summary of fractions of epitope-specific CD8+ T cell responses with one, two, three, four, and five antigen-specific functions in 11 untreated patients (nRx); (B) summary of fractions of eight epitope-specific CD8+ T cell responses for seven patients before and after receiving antiretroviral therapy (Rx). Frequencies of different combination of epitope-specific CD8+ T cell functions were quantified with Boolean gates using FlowJo software, and fractions were calculated from total epitope-specific CD8+ T cell response. Each of the combination of epitope-specific functions (1–5) is shown separately before (“early”) and after (“late”) antiretroviral treatment initiation for the treated study group (Rx) or for a corresponding early and late time point in the untreated group (nRx), respectively. The monofunctional fraction of the HIV-1–specific CD8+ T cell response increased significantly (p < 0.05) in comparison to a decrease of the monofunctional fraction of the HIV-1–specific CD8+ T cell response in the treated group (*). In addition, the increase of the four-functional fraction of the HIV-1–specific CD8+ T cell responses in the treated group was significant (p < 0.05) in comparison to the decrease of the four-functional fraction in the untreated group (*). We used the general linear model to test two-way interaction effects between observation period and group (nRx versus Rx) to calculate significance, and standard errors of the estimate were adjusted for clustering by patient.

Mentions: We next compared for the entire group of untreated and treated study patients the functional profile of all epitope-specific CD8+ T cell responses detected at an early time point before treatment initiation and a late time point after treatment initiation or a respective time point in the untreated group (Table 1). Each fraction of function was calculated as a percentage of the total CD8+ T cell response as described above. In the untreated patients, the functional profile of epitope-specific CD8+ T cell responses decreased over time, while the fraction of virus-specific CD8+ T cells with a single cytokine/chemokine function increased (Figure 2A and Table S1). In contrast, the functional profile of epitope-specific CD8+ T cells in treated study patients remained stable or broadened (Figure 2B and Table S1). A significant (p < 0.05) two-way interaction effect was detected between treatment and observation period, where the effect of observation period was expected to produce opposite effects by group. In this case, an appreciable increase of the single cytokine/chemokine function was observed in untreated patients (Figure 2A), contrasting the decrease of the monofunctional responses in the treated patients (Figure 2B, p < 0.05). Similarly, the contribution of four-functional CD8+ T cell responses decreased in the untreated group, while it slightly increased in the treated group (p < 0.05). In contrast to the significant changes in the functionality of HIV-1–specific CD8+ T cells in the presence or absence of HIV-1 antigen, CMV-, Flu-, or EBV-specific CD8+ T cell functions did not change significantly over time (see Figure S1), indicating that HIV-1 antigenemia itself was the driving force for the qualitative changes in the HIV-1–specific CD8+ T cell functionality. The more restricted functional profile of CEF-specific CD8+ T cell responses in our study compared to a previous publication [16] might be due to the more restrictive definition of a positive individual cytokine response (twice above background) before Boolean gating used here, and substantial difference in the clinical characteristics of the study cohorts (primary versus chronic HIV-1 infection). Taken together, these longitudinal studies of HIV-1–specific CD8+ T cell functionality in individuals with treated and untreated primary HIV-1 infection demonstrate that the quality of an epitope-specific CD8+ T cell response remains stable or improves in the absence of antigen following initiation of antiretroviral therapy but decreases in the presence of persistent antigen.


Antigen load and viral sequence diversification determine the functional profile of HIV-1-specific CD8+ T cells.

Streeck H, Brumme ZL, Anastario M, Cohen KW, Jolin JS, Meier A, Brumme CJ, Rosenberg ES, Alter G, Allen TM, Walker BD, Altfeld M - PLoS Med. (2008)

Loss of Epitope-Specific CD8+ T Cell Functionality during Antigen Persistence(A) Summary of fractions of epitope-specific CD8+ T cell responses with one, two, three, four, and five antigen-specific functions in 11 untreated patients (nRx); (B) summary of fractions of eight epitope-specific CD8+ T cell responses for seven patients before and after receiving antiretroviral therapy (Rx). Frequencies of different combination of epitope-specific CD8+ T cell functions were quantified with Boolean gates using FlowJo software, and fractions were calculated from total epitope-specific CD8+ T cell response. Each of the combination of epitope-specific functions (1–5) is shown separately before (“early”) and after (“late”) antiretroviral treatment initiation for the treated study group (Rx) or for a corresponding early and late time point in the untreated group (nRx), respectively. The monofunctional fraction of the HIV-1–specific CD8+ T cell response increased significantly (p < 0.05) in comparison to a decrease of the monofunctional fraction of the HIV-1–specific CD8+ T cell response in the treated group (*). In addition, the increase of the four-functional fraction of the HIV-1–specific CD8+ T cell responses in the treated group was significant (p < 0.05) in comparison to the decrease of the four-functional fraction in the untreated group (*). We used the general linear model to test two-way interaction effects between observation period and group (nRx versus Rx) to calculate significance, and standard errors of the estimate were adjusted for clustering by patient.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2365971&req=5

pmed-0050100-g002: Loss of Epitope-Specific CD8+ T Cell Functionality during Antigen Persistence(A) Summary of fractions of epitope-specific CD8+ T cell responses with one, two, three, four, and five antigen-specific functions in 11 untreated patients (nRx); (B) summary of fractions of eight epitope-specific CD8+ T cell responses for seven patients before and after receiving antiretroviral therapy (Rx). Frequencies of different combination of epitope-specific CD8+ T cell functions were quantified with Boolean gates using FlowJo software, and fractions were calculated from total epitope-specific CD8+ T cell response. Each of the combination of epitope-specific functions (1–5) is shown separately before (“early”) and after (“late”) antiretroviral treatment initiation for the treated study group (Rx) or for a corresponding early and late time point in the untreated group (nRx), respectively. The monofunctional fraction of the HIV-1–specific CD8+ T cell response increased significantly (p < 0.05) in comparison to a decrease of the monofunctional fraction of the HIV-1–specific CD8+ T cell response in the treated group (*). In addition, the increase of the four-functional fraction of the HIV-1–specific CD8+ T cell responses in the treated group was significant (p < 0.05) in comparison to the decrease of the four-functional fraction in the untreated group (*). We used the general linear model to test two-way interaction effects between observation period and group (nRx versus Rx) to calculate significance, and standard errors of the estimate were adjusted for clustering by patient.
Mentions: We next compared for the entire group of untreated and treated study patients the functional profile of all epitope-specific CD8+ T cell responses detected at an early time point before treatment initiation and a late time point after treatment initiation or a respective time point in the untreated group (Table 1). Each fraction of function was calculated as a percentage of the total CD8+ T cell response as described above. In the untreated patients, the functional profile of epitope-specific CD8+ T cell responses decreased over time, while the fraction of virus-specific CD8+ T cells with a single cytokine/chemokine function increased (Figure 2A and Table S1). In contrast, the functional profile of epitope-specific CD8+ T cells in treated study patients remained stable or broadened (Figure 2B and Table S1). A significant (p < 0.05) two-way interaction effect was detected between treatment and observation period, where the effect of observation period was expected to produce opposite effects by group. In this case, an appreciable increase of the single cytokine/chemokine function was observed in untreated patients (Figure 2A), contrasting the decrease of the monofunctional responses in the treated patients (Figure 2B, p < 0.05). Similarly, the contribution of four-functional CD8+ T cell responses decreased in the untreated group, while it slightly increased in the treated group (p < 0.05). In contrast to the significant changes in the functionality of HIV-1–specific CD8+ T cells in the presence or absence of HIV-1 antigen, CMV-, Flu-, or EBV-specific CD8+ T cell functions did not change significantly over time (see Figure S1), indicating that HIV-1 antigenemia itself was the driving force for the qualitative changes in the HIV-1–specific CD8+ T cell functionality. The more restricted functional profile of CEF-specific CD8+ T cell responses in our study compared to a previous publication [16] might be due to the more restrictive definition of a positive individual cytokine response (twice above background) before Boolean gating used here, and substantial difference in the clinical characteristics of the study cohorts (primary versus chronic HIV-1 infection). Taken together, these longitudinal studies of HIV-1–specific CD8+ T cell functionality in individuals with treated and untreated primary HIV-1 infection demonstrate that the quality of an epitope-specific CD8+ T cell response remains stable or improves in the absence of antigen following initiation of antiretroviral therapy but decreases in the presence of persistent antigen.

Bottom Line: Virus-specific CD8(+) T lymphocytes play a key role in the initial reduction of peak viremia during acute viral infections, but display signs of increasing dysfunction and exhaustion under conditions of chronic antigen persistence.This exhausted phenotype significantly decreased upon removal of stimulation by antigen, either in response to antiretroviral therapy or by reduction of epitope-specific antigen load in the presence of ongoing viral replication, as a consequence of in vivo selection of cytotoxic T lymphocyte escape mutations in the respective epitopes.Monofunctionality increased in CD8(+) T cell responses directed against conserved epitopes from 49% (95% confidence interval 27%-72%) to 76% (56%-95%) (standard deviation [SD] of the effect size 0.71), while monofunctionality remained stable or slightly decreased for responses directed against escaped epitopes from 61% (47%-75%) to 56% (42%-70%) (SD of the effect size 0.18) (p < 0.05).

View Article: PubMed Central - PubMed

Affiliation: Partners AIDS Research Center, Infectious Disease Unit, Massachusetts General Hospital and Division of AIDS, Harvard Medical School, Boston, Massachusetts, United States of America.

ABSTRACT

Background: Virus-specific CD8(+) T lymphocytes play a key role in the initial reduction of peak viremia during acute viral infections, but display signs of increasing dysfunction and exhaustion under conditions of chronic antigen persistence. It has been suggested that virus-specific CD8(+) T cells with a "polyfunctional" profile, defined by the capacity to secrete multiple cytokines or chemokines, are most competent in controlling viral replication in chronic HIV-1 infection. We used HIV-1 infection as a model of chronic persistent viral infection to investigate the process of exhaustion and dysfunction of virus-specific CD8(+) T cell responses on the single-epitope level over time, starting in primary HIV-1 infection.

Methods and findings: We longitudinally analyzed the polyfunctional epitope-specific CD8(+) T cell responses of 18 patients during primary HIV-1 infection before and after therapy initiation or sequence variation in the targeted epitope. Epitope-specific CD8(+) T cells responded with multiple effector functions to antigenic stimulation during primary HIV-1 infection, but lost their polyfunctional capacity in response to antigen and up-regulated programmed death 1 (PD-1) expression with persistent viremic infection. This exhausted phenotype significantly decreased upon removal of stimulation by antigen, either in response to antiretroviral therapy or by reduction of epitope-specific antigen load in the presence of ongoing viral replication, as a consequence of in vivo selection of cytotoxic T lymphocyte escape mutations in the respective epitopes. Monofunctionality increased in CD8(+) T cell responses directed against conserved epitopes from 49% (95% confidence interval 27%-72%) to 76% (56%-95%) (standard deviation [SD] of the effect size 0.71), while monofunctionality remained stable or slightly decreased for responses directed against escaped epitopes from 61% (47%-75%) to 56% (42%-70%) (SD of the effect size 0.18) (p < 0.05).

Conclusion: These data suggest that persistence of antigen can be the cause, rather than the consequence, of the functional impairment of virus-specific T cell responses observed during chronic HIV-1 infection, and underscore the importance of evaluating autologous viral sequences in studies aimed at investigating the relationship between virus-specific immunity and associated pathogenesis.

Show MeSH
Related in: MedlinePlus