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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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Representative Multifunctional Composition of Epitope-Specific CD8+ T Cell Responses against Conserved Epitopes or Epitopes with Sequence Variations in an Untreated Patient (Ac-211)(A) Epitope-specific CD8+ T cell responses against four HIV-1 epitopes were studied during primary and chronic HIV-1 infection in this patient (Ac-211). All 32 possible combinations of the five antigen-specific functions studied for each epitope are shown on the x-axis, and the contribution of each epitope-specific CD8+ T cell population exhibiting the respective combination of functions to the total epitope-specific response are indicated as bars. Responses are grouped and color-coded according to the number of functions (1 = yellow, 2 = cyan, 3 = green, 4 = blue, 5 = red). Dark grey bars show the results from the early sample; light grey bars show the results from the later samples. The data are summarized by pie charts in which each slice of the pie represents the fraction of the total epitope-specific response that consists of CD8+ T cells with the respective number of functions. Pie charts on the left represent the fraction of the respective epitope-specific CD8+ T cell responses during primary HIV-1 infection (early), while pie charts on the right represent the later time point (late). Amino acid sequences of each studied epitope during the early and late time point are indicated next to each graph. Amino acid substitutions within the epitope are highlighted in red shading. The functionality of the CD8+ T cell responses against the epitopes B8-EI9 in p24, B8-FL8 in Nef and Cw7-KY11 in Nef decreased to a primarily monofunctional composition, while the fraction of monofunctional epitope-specific CD8+ T cells decreased, and two- and three functional responses increased, for the epitope A3-RK9 in p17. The amino acid sequence of the A3-RK9 epitope displayed a substitution at the anchor residue position 9 from lysine (K) → arginine (R).(B) Comparison of the functional avidity of CD8+ T cells specific for two epitopes and their respective variants within the same individual (Ac-211). Upper graph: Intraindividual comparison of the recognition of the B8-FL8 (Nef) wild type (WT) and the B8-FL8 K5Q variant measured by serial log dilution of both peptides. IC50 was calculated and is indicated in the figure. The variant peptide was recognized with similar functional avidity at all concentrations to the B8-FL8 WT peptide. Lower graph: Intraindividual comparison of the recognition of the A3-RK9 WT versus the A3-RK9 K9R variant was measured by serial log dilutions of both peptides. IC50 was calculated and is indicated in the figure. The variant peptide was recognized with much lower functional avidity at all concentrations than was the A3-RK9 WT peptide.
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pmed-0050100-g003: Representative Multifunctional Composition of Epitope-Specific CD8+ T Cell Responses against Conserved Epitopes or Epitopes with Sequence Variations in an Untreated Patient (Ac-211)(A) Epitope-specific CD8+ T cell responses against four HIV-1 epitopes were studied during primary and chronic HIV-1 infection in this patient (Ac-211). All 32 possible combinations of the five antigen-specific functions studied for each epitope are shown on the x-axis, and the contribution of each epitope-specific CD8+ T cell population exhibiting the respective combination of functions to the total epitope-specific response are indicated as bars. Responses are grouped and color-coded according to the number of functions (1 = yellow, 2 = cyan, 3 = green, 4 = blue, 5 = red). Dark grey bars show the results from the early sample; light grey bars show the results from the later samples. The data are summarized by pie charts in which each slice of the pie represents the fraction of the total epitope-specific response that consists of CD8+ T cells with the respective number of functions. Pie charts on the left represent the fraction of the respective epitope-specific CD8+ T cell responses during primary HIV-1 infection (early), while pie charts on the right represent the later time point (late). Amino acid sequences of each studied epitope during the early and late time point are indicated next to each graph. Amino acid substitutions within the epitope are highlighted in red shading. The functionality of the CD8+ T cell responses against the epitopes B8-EI9 in p24, B8-FL8 in Nef and Cw7-KY11 in Nef decreased to a primarily monofunctional composition, while the fraction of monofunctional epitope-specific CD8+ T cells decreased, and two- and three functional responses increased, for the epitope A3-RK9 in p17. The amino acid sequence of the A3-RK9 epitope displayed a substitution at the anchor residue position 9 from lysine (K) → arginine (R).(B) Comparison of the functional avidity of CD8+ T cells specific for two epitopes and their respective variants within the same individual (Ac-211). Upper graph: Intraindividual comparison of the recognition of the B8-FL8 (Nef) wild type (WT) and the B8-FL8 K5Q variant measured by serial log dilution of both peptides. IC50 was calculated and is indicated in the figure. The variant peptide was recognized with similar functional avidity at all concentrations to the B8-FL8 WT peptide. Lower graph: Intraindividual comparison of the recognition of the A3-RK9 WT versus the A3-RK9 K9R variant was measured by serial log dilutions of both peptides. IC50 was calculated and is indicated in the figure. The variant peptide was recognized with much lower functional avidity at all concentrations than was the A3-RK9 WT peptide.

Mentions: As exemplified for one untreated study patient in Figure 3A (Ac-211), the CD8+ T cell response against the HLA-Cw7–restricted epitope KRQDILDLWVY (Cw7-KY11) in Nef lost the capability for a “polyfunctional” response and became predominantly (64%) monofunctional (Figure 3A). Similarly, the T cell responses against the HLA-B8-restricted epitopes FLKEKGGL (B8-FL8) in Nef and EIYKRWII (B8-EI8) in p24 Gag included at the first time point a mixture of CD8+ T cells able to exhibit up to three different functions following antigenic stimulation, but became predominantly monofunctional (75% and 95% respectively) at the later time point. In contrast, the response against the HLA-A3–restricted epitope RLRPGGKKK (A3-RK9) in p17 Gag increased from a 100% monofunctional response to a dual- and triple-functional response in the same patient. Sequence analysis within these epitopes revealed a conservation of the sequences within the Cw7-KY11 and B8-EI8 epitopes during the study period, while the B8-FL8 and the A3-RK9 epitopes revealed amino acid substitutions (A3-RK9 at position 9 from K to R, and B8-FL8 at position 5 from K to Q; see Figure 3A and Table 2). While the change from lysine to glutamine in B8-FL8 had no significant impact on the recognition by CD8+ T cells and was recognized with comparable functional avidity to the wild-type sequence, the K-to-R mutation in the A3-RK9 epitope resulted in a much lower functional avidity, in line with previous studies (see Figure 3B) [27]. These data in a single individual suggest that sequence variations within a targeted CD8+ T cell epitope that lead to lost or reduced recognition of the epitope can result in an increase in the functional profile of the respective epitope-specific CD8+ T cell population.


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)

Representative Multifunctional Composition of Epitope-Specific CD8+ T Cell Responses against Conserved Epitopes or Epitopes with Sequence Variations in an Untreated Patient (Ac-211)(A) Epitope-specific CD8+ T cell responses against four HIV-1 epitopes were studied during primary and chronic HIV-1 infection in this patient (Ac-211). All 32 possible combinations of the five antigen-specific functions studied for each epitope are shown on the x-axis, and the contribution of each epitope-specific CD8+ T cell population exhibiting the respective combination of functions to the total epitope-specific response are indicated as bars. Responses are grouped and color-coded according to the number of functions (1 = yellow, 2 = cyan, 3 = green, 4 = blue, 5 = red). Dark grey bars show the results from the early sample; light grey bars show the results from the later samples. The data are summarized by pie charts in which each slice of the pie represents the fraction of the total epitope-specific response that consists of CD8+ T cells with the respective number of functions. Pie charts on the left represent the fraction of the respective epitope-specific CD8+ T cell responses during primary HIV-1 infection (early), while pie charts on the right represent the later time point (late). Amino acid sequences of each studied epitope during the early and late time point are indicated next to each graph. Amino acid substitutions within the epitope are highlighted in red shading. The functionality of the CD8+ T cell responses against the epitopes B8-EI9 in p24, B8-FL8 in Nef and Cw7-KY11 in Nef decreased to a primarily monofunctional composition, while the fraction of monofunctional epitope-specific CD8+ T cells decreased, and two- and three functional responses increased, for the epitope A3-RK9 in p17. The amino acid sequence of the A3-RK9 epitope displayed a substitution at the anchor residue position 9 from lysine (K) → arginine (R).(B) Comparison of the functional avidity of CD8+ T cells specific for two epitopes and their respective variants within the same individual (Ac-211). Upper graph: Intraindividual comparison of the recognition of the B8-FL8 (Nef) wild type (WT) and the B8-FL8 K5Q variant measured by serial log dilution of both peptides. IC50 was calculated and is indicated in the figure. The variant peptide was recognized with similar functional avidity at all concentrations to the B8-FL8 WT peptide. Lower graph: Intraindividual comparison of the recognition of the A3-RK9 WT versus the A3-RK9 K9R variant was measured by serial log dilutions of both peptides. IC50 was calculated and is indicated in the figure. The variant peptide was recognized with much lower functional avidity at all concentrations than was the A3-RK9 WT peptide.
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Related In: Results  -  Collection

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getmorefigures.php?uid=PMC2365971&req=5

pmed-0050100-g003: Representative Multifunctional Composition of Epitope-Specific CD8+ T Cell Responses against Conserved Epitopes or Epitopes with Sequence Variations in an Untreated Patient (Ac-211)(A) Epitope-specific CD8+ T cell responses against four HIV-1 epitopes were studied during primary and chronic HIV-1 infection in this patient (Ac-211). All 32 possible combinations of the five antigen-specific functions studied for each epitope are shown on the x-axis, and the contribution of each epitope-specific CD8+ T cell population exhibiting the respective combination of functions to the total epitope-specific response are indicated as bars. Responses are grouped and color-coded according to the number of functions (1 = yellow, 2 = cyan, 3 = green, 4 = blue, 5 = red). Dark grey bars show the results from the early sample; light grey bars show the results from the later samples. The data are summarized by pie charts in which each slice of the pie represents the fraction of the total epitope-specific response that consists of CD8+ T cells with the respective number of functions. Pie charts on the left represent the fraction of the respective epitope-specific CD8+ T cell responses during primary HIV-1 infection (early), while pie charts on the right represent the later time point (late). Amino acid sequences of each studied epitope during the early and late time point are indicated next to each graph. Amino acid substitutions within the epitope are highlighted in red shading. The functionality of the CD8+ T cell responses against the epitopes B8-EI9 in p24, B8-FL8 in Nef and Cw7-KY11 in Nef decreased to a primarily monofunctional composition, while the fraction of monofunctional epitope-specific CD8+ T cells decreased, and two- and three functional responses increased, for the epitope A3-RK9 in p17. The amino acid sequence of the A3-RK9 epitope displayed a substitution at the anchor residue position 9 from lysine (K) → arginine (R).(B) Comparison of the functional avidity of CD8+ T cells specific for two epitopes and their respective variants within the same individual (Ac-211). Upper graph: Intraindividual comparison of the recognition of the B8-FL8 (Nef) wild type (WT) and the B8-FL8 K5Q variant measured by serial log dilution of both peptides. IC50 was calculated and is indicated in the figure. The variant peptide was recognized with similar functional avidity at all concentrations to the B8-FL8 WT peptide. Lower graph: Intraindividual comparison of the recognition of the A3-RK9 WT versus the A3-RK9 K9R variant was measured by serial log dilutions of both peptides. IC50 was calculated and is indicated in the figure. The variant peptide was recognized with much lower functional avidity at all concentrations than was the A3-RK9 WT peptide.
Mentions: As exemplified for one untreated study patient in Figure 3A (Ac-211), the CD8+ T cell response against the HLA-Cw7–restricted epitope KRQDILDLWVY (Cw7-KY11) in Nef lost the capability for a “polyfunctional” response and became predominantly (64%) monofunctional (Figure 3A). Similarly, the T cell responses against the HLA-B8-restricted epitopes FLKEKGGL (B8-FL8) in Nef and EIYKRWII (B8-EI8) in p24 Gag included at the first time point a mixture of CD8+ T cells able to exhibit up to three different functions following antigenic stimulation, but became predominantly monofunctional (75% and 95% respectively) at the later time point. In contrast, the response against the HLA-A3–restricted epitope RLRPGGKKK (A3-RK9) in p17 Gag increased from a 100% monofunctional response to a dual- and triple-functional response in the same patient. Sequence analysis within these epitopes revealed a conservation of the sequences within the Cw7-KY11 and B8-EI8 epitopes during the study period, while the B8-FL8 and the A3-RK9 epitopes revealed amino acid substitutions (A3-RK9 at position 9 from K to R, and B8-FL8 at position 5 from K to Q; see Figure 3A and Table 2). While the change from lysine to glutamine in B8-FL8 had no significant impact on the recognition by CD8+ T cells and was recognized with comparable functional avidity to the wild-type sequence, the K-to-R mutation in the A3-RK9 epitope resulted in a much lower functional avidity, in line with previous studies (see Figure 3B) [27]. These data in a single individual suggest that sequence variations within a targeted CD8+ T cell epitope that lead to lost or reduced recognition of the epitope can result in an increase in the functional profile of the respective epitope-specific CD8+ T cell population.

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