The Impact of B-Cell Perturbations on Pneumococcal Conjugate Vaccine Response in HIV-Infected Adults

<div><p>Untreated HIV infection results in severe perturbations of the B-cell population and hyporesponsiveness to vaccination. We studied associations between circulating B-cell subsets and antibody response to pneumococcal conjugate vaccine in treated and untreated HIV patients.</p> <p>Ninety-five HIV-infected adults were grouped according to antiretroviral therapy (ART) and CD4+ cell count as follows: 20 ART-naïve (no prior ART), 62 ART-responders (received ART, and CD4 count >500 cells/µl), and 13 impaired responders (received ART for more than 3 years, and CD4 count <500 cells/µl). All subjects were immunized twice with double-dose 7-valent pneumococcal conjugate vaccine with or without 1 mg CPG 7909 (toll-like receptor 9 agonist) at baseline and after three months. Pre-vaccination B-cell subpopulations were assessed by flow cytometry. Serum IgG concentrations for vaccine serotypes were quantified by ELISA at baseline and 3, 4, and 9 months post-vaccination. ART responders had more isotype-switched memory B cells and more marginal-zone (MZ)-like B cells compared with impaired responders. Furthermore, ART-naïve patients had higher concentration of transitional B cells and plasmablasts compared with B cells of other patient groups. The concentration of MZ-like, isotype switched memory cells and plasmablasts correlated positively with post-vaccination IgG concentration at 3, 4, and 9 months. Low concentrations of isotype-switched memory B cells was the strongest independent predictor of poor pneumococcal conjugate vaccine responsiveness, emphasizing that B-cell subset disturbances are associated with poor vaccine response among HIV-infected patients</p> </div

Baseline characteristics of the study population at the time of inclusion.

<p>ART; antiretroviral therapy, CPG 7909; toll-like receptor 9 agonist, IQR; Interquartile range, BMI; body mass index, PPV-23; 23-valent pneumococcal polysaccharide vaccine.</p

Adjusted regression analysis: Baseline B-cell subpopulations as predictors for IgG antibody titers.

<p>IgG antibody concentration is calculated as the relative vaccine-specific IgG increase of the 7 <i>Streptococcus pneumoniae</i> polysaccharide serotypes contained in the PCV-7 vaccine from pre-vaccination baseline to 3, 4 and 9 months, measured by ELISA.</p><p>B-cell counts are calculated as the routine lab lymphocyte count multiplied with the B-cell percentage of lymphocytes measured by flow cytometry.</p><p>Adjusted for patient group (‘ART-naïve’, ‘impaired responders’, ‘ART-responders’), CPG7909 adjuvant (yes/no) and current smoker (yes/no).</p><p>RC; Regression Coefficient (increase in log(µg IgG/ml) with 10-fold increase in cell counts/fractions), p; p-value, n; number of participants.</p><p>Transitional; IgD+, IgM+, CD27−, CD38+ B cells, Naive; IgD+, IgM+/−, CD27−, CD38− B cells, MZ-like; marginal zone-like B cells (IgD+, IgM+, CD27+, CD38−), IgM-only memory; IgD−, IgM+, CD27+, CD38− B cells, ITS memory; isotype switched memory B cells (IgD−, IgM−, CD27+, CD38−), ITS plasmablasts; isotype switched plasmablasts (IgD−, IgM−, CD27+, CD38+).</p

Administration of a Toll-Like Receptor 9 Agonist Decreases the Proviral Reservoir in Virologically Suppressed HIV-Infected Patients

<div><p></p><p>Toll-like receptor (TLR) agonists can reactivate HIV from latently infected cells in vitro. We aimed to investigate the TLR-9 agonist, CPG 7909's <i>in vivo</i> effect on the proviral HIV reservoir and HIV-specific immunity. This was a post-hoc analysis of a double-blind randomized controlled vaccine trial. HIV-infected adults were randomized 1∶1 to receive pneumococcal vaccines with or without 1 mg CPG 7909 as adjuvant at 0, 3 and 9 months. In patients on suppressive antiretroviral therapy we quantified proviral DNA at 0, 3, 4, 9, and 10 months (31 subjects in the CPG group and 37 in the placebo-adjuvant group). Furthermore, we measured HIV-specific antibodies, characterized T cell phenotypes and HIV-specific T cell immunity. We observed a mean reduction in proviral DNA in the CPG group of 12.6% (95% CI: −23.6–0.0) following each immunization whereas proviral DNA in the placebo-adjuvant group remained largely unchanged (6.7% increase; 95% CI: −4.2–19.0 after each immunization, p = 0.02). Among participants with additional cryo-preserved PBMCs, HIV-specific CD8+ T cell immunity as indicated by increased expression of degranulation marker CD107a and macrophage inflammatory protein 1β (MIP1β) tended to be up-regulated following immunization with CPG 7909 compared with placebo as adjuvant. Further, increasing proportion of HIV-specific CD107a and MIP1β-expressing CD8+ T cells were strongly correlated with decreasing proviral load. No changes were observed in T cell phenotype distribution, HIV-specific CD4+ T cell immunity, or HIV-specific antibodies. TLR9-adjuvanted pneumococcal vaccination decreased proviral load. Reductions in proviral load correlated with increasing levels of HIV specific CD8+ T cells. Further investigation into the potential effect of TLR9 agonists on HIV latency is warranted.</p></div

Flow chart of inclusion and follow up.

<p>Flow chart of inclusion and follow up.</p

HIV-specific T cell immunity.

<p>Percentage of cells expressing CD107a, MIP1β and IFNγ before and after the 3^rd immunization in the <b>(A)</b> CD4+ T cell compartment and <b>(B)</b> CD8+ T cell compartment. Bars show mean with SEM. N = 17 (placebo = 10, CPG = 7). Statistical comparisons were made between the change from before and after the 3^rd immunization in the two groups.</p

Changes from baseline in markers of impaired renal function.

<p>Changes from baseline to the indicated time points in estimated creatinine clearance (a), levels of plasma cystatin C at baseline and week 48 (b), changes from baseline to week 48 in plasma cystatin C (c), and changes from baseline to the last measurement in ratios of urinary biomarkers relative to urine creatinine concentration (d, e, f). Changes in urinary biomarkers (d, e, f) were evaluated in 29 patients (15 in the TDF/FTC arm and 14 in the ABC/3TC arm); of these, 24 were followed from baseline to week 48. Error bars in (a) show 95% confidence intervals; the horizontal line in (c) represents the mean value, while the horizontal lines in (d, e, f) represent median values. eCrCl = estimated creatinine clearance; NGAL = neutrophil gelatinase-associated lipocalin TDF/FTC = tenofovir/emtricitabine; ABC/3TC = abacavir/lamivudine.</p

Baseline Characteristics of the Study Population at Time of Inclusion in the Study.

<p>Note: Data are no. (%) of patients, unless otherwise is indicated. BMI, body mass index; PBMCs, IQR, interquartile range.</p

Disposition of study participants.

<p>HAART, highly active antiretroviral therapy.</p