Cheryl Chairez

CD4+ T Cells, Including Th17 and Cycling Subsets, Are Intact in the Gut Mucosa of HIV-1-Infected Long-Term Nonprogressors

ABSTRACT During acute human immunodeficiency virus (HIV) infection, there is a massive depletion of CD4+ T cells in the gut mucosa that can be reversed to various degrees with antiretroviral therapy. Th17 cells have been implicated in mucosal immunity to extracellular bacteria, and preservation of this subset may support gut mucosal immune recovery. However, this possibility has not yet been evaluated in HIV-1-infected long-term nonprogressors (LTNPs), who maintain high CD4+ T cell counts and suppress viral replication in the absence of antiretroviral therapy. In this study, we evaluated the immunophenotype and function of CD4+ T cells in peripheral blood and gut mucosa of HIV-uninfected controls, LTNPs, and HIV-1-infected individuals treated with prolonged antiretroviral therapy (ART) (VL [viral load]<50). We found that LTNPs have intact CD4+ T cell populations, including Th17 and cycling subsets, in the gut mucosa and a preserved T cell population expressing gut homing molecules in the peripheral blood. In addition, we observed no evidence of higher monocyte activation in LTNPs than in HIV-infected (HIV−) controls. These data suggest that, similar to nonpathogenic simian immunodeficiency virus (SIV) infection, LTNPs preserve the balance of CD4+ T cell populations in blood and gut mucosa, which may contribute to the lack of disease progression observed in these patients.

Cycling of Gut Mucosal CD4+ T Cells Decreases after Prolonged Anti-Retroviral Therapy and is Associated with Plasma LPS Levels

The gut mucosa is an important site of HIV immunopathogenesis with severe depletion of CD4+ T cells occurring during acute infection. The effect of prolonged anti-retroviral therapy (ART) on cycling and restoration of T lymphocytes in the gut remains unclear. Colon and terminal ileal biopsies and peripheral blood samples were collected from viremic, untreated, HIV-infected participants, patients treated with prolonged ART (>5 years), and uninfected controls and analyzed by flow cytometry. In the gut, the proportion of cycling T cells decreased and the number of CD4+ T cells normalized in treated patients in parallel with β7 expression on CD4+ T cells in blood. Cycling of gut T cells in viremic patients was associated with increased plasma LPS levels, but not colonic HIV–RNA. These data suggest that gut T-cell activation and microbial translocation may be interconnected whereas prolonged ART may decrease activation and restore gut CD4+ T cells.

Influence of Panax ginseng on Cytochrome P450 (CYP)3A and P-glycoprotein (P-gp) Activity in Healthy Participants

A number of herbal preparations have been shown to interact with prescription medications secondary to modulation of cytochrome P450 (CYP) and/or P‐glycoprotein (P‐gp). The purpose of this study was to determine the influence of Panax ginseng on CYP3A and P‐gp function using the probe substrates midazolam and fexofenadine, respectively. Twelve healthy participants (8 men) completed this open‐label, single‐sequence pharmacokinetic study. Healthy volunteers received single oral doses of midazolam 8 mg and fexofenadine 120 mg, before and after 28 days of P ginseng 500 mg twice daily. Midazolam and fexofenadine pharmacokinetic parameter values were calculated and compared before and after P ginseng administration. Geometric mean ratios (postginseng/preginseng) for midazolam area under the concentration‐time curve from zero to infinity (AUC0‐∞), half‐life (t1/2), and maximum concentration (Cmax) were significantly reduced at 0.66 (0.55–0.78), 0.71 (0.53–0.90), and 0.74 (0.56–0.93), respectively. Conversely, fexofenadine pharmacokinetics were unaltered by P ginseng administration. Based on these results, P ginseng appeared to induce CYP3A activity in the liver and possibly the gastrointestinal tract. Patients taking P ginseng in combination with CYP3A substrates with narrow therapeutic ranges should be monitored closely for adequate therapeutic response to the substrate medication.

Echinacea purpurea Significantly Induces Cytochrome P450 3A Activity but Does Not Alter Lopinavir-Ritonavir Exposure in Healthy Subjects

Study Objective. To determine the influence of Echinacea purpurea on the pharmacokinetics of lopinavir‐ritonavir and on cytochrome P450 (CYP)3A and P‐glycoprotein activity by using the probe substrates midazolam and fexofenadine, respectively.

Comprehensive analysis of unique cases with extraordinary control over HIV replication.

True long-term nonprogressors (LTNPs)/elite controllers (ECs) maintain durable control over HIV replication without antiretroviral therapy. Herein we describe 4 unique persons who were distinct from conventional LTNPs/ECs in that they had extraordinarily low HIV burdens and comparatively weak immune responses. As a group, typical LTNPs/ECs have unequivocally reactive HIV-1 Western blots, viral loads below the lower threshold of clinical assays, low levels of persistent viral reservoirs, an over-representation of protective HLA alleles, and robust HIV-specific CD8(+) T-cell responses. The 4 unique cases were distinguished from typical LTNPs/ECs based on weakly reactive Western blots, undetectable plasma viremia by a single copy assay, extremely low to undetectable HIV DNA levels, and difficult to isolate replication-competent virus. All 4 had at least one protective HLA allele and CD8(+) T-cell responses that were disproportionately high for the low antigen levels but comparatively lower than those of typical LTNPs/ECs. These unique persons exhibit extraordinary suppression over HIV replication, therefore, higher-level control than has been demonstrated in previous studies of LTNPs/ECs. Additional insight into the full spectrum of immune-mediated suppression over HIV replication may enhance our understanding of the associated mechanisms, which should inform the design of efficacious HIV vaccines and immunotherapies.

Lack of Compartmentalization of HIV-1 Quasispecies Between the Gut and Peripheral Blood Compartments

Compartmental differences in human immunodeficiency virus type 1 (HIV-1) between the gut and peripheral blood and within the gut were examined. Biopsy specimens from the colon and ileum and peripheral blood samples were collected from chronically HIV-1-infected individuals. HIV-1 envelope sequences were examined from cell-associated DNA and RNA and virion RNA. Phylogenetic analysis revealed no evidence of compartmentalization of HIV-1 between the gut and peripheral blood and within the gut (colon and ileum). HIV-1 sequences detected in the gut were transcriptionally active and were also found in peripheral blood from matching time points, providing evidence of ongoing virus production in the gut and equilibrium of HIV-1 between the gut and peripheral blood compartments.

Influence of Low-dose Ritonavir With and Without Darunavir on the Pharmacokinetics and Pharmacodynamics of Inhaled Beclomethasone

Objective:To identify an alternative inhaled corticosteroid to fluticasone propionate that can be safely coadministered with HIV protease inhibitors, the safety and pharmacokinetics of beclomethasone dipropionate (BDP) and its active metabolite, beclomethasone 17-monopropionate (17-BMP), in combination with ritonavir (RTV) and darunavir/ritonavir (DRV/r) were assessed. Design:Open-label, prospective, randomized pharmacokinetic and pharmacodynamic study in healthy volunteers. Methods:Thirty healthy volunteers received inhaled 160 &mgr;g bid BDP for 14 days and were then randomized (1:1:1) into 3 groups: group 1 (control) remained on BDP alone for 28 days, group 2 received 100 mg bid BDP + RTV for 28 days, and group 3 received 600/100 mg bid BDP + DRV/r for 28 days. Pharmacokinetic sampling for 17-BMP was performed on days 14 and 28, and pharmacokinetic parameter values were compared within patients and between groups. Cortisol stimulation testing was also performed on days 1, 14, 28, and 42 and compared within and between groups. Results:Geometric mean ratios (day 28:day 14) (90% confidence interval) for 17-BMP area under the concentration–time curve in groups 1, 2, and 3, respectively, were 0.93 (0.81 to 1.06, P = 0.27), 2.08 (1.52 to 2.65, P = 0.006), and 0.89 (0.68 to 1.09, P = 0.61). There were no significant reductions in serum cortisol levels within or between groups (P > 0.05). Conclusions:DRV/r did not increase 17-BMP exposure, whereas RTV alone produced a statistically significant but clinically inconsequential 2-fold increase in 17-BMP exposure. Adrenal suppression was not observed in any of the study groups. These data suggest that BDP can be safely coadministered with DRV/r and likely other RTV-boosted protease inhibitors.

Gemfibrozil concentrations are significantly decreased in the presence of lopinavir-ritonavir.

Objective:The objective of this study was to determine the influence of a 2-week course of lopinavir-ritonavir on the pharmacokinetics of the triglyceride-lowering agent, gemfibrozil. Methods:The study was conducted as an open label, single-sequence pharmacokinetic study in healthy human volunteers. Gemfibrozil pharmacokinetic parameter values were compared using a Student t test after a single 600-mg dose was administered to healthy volunteers before and after 2 weeks of lopinavir-ritonavir (400/100 mg) twice daily. Results:Fifteen healthy volunteers (eight males) completed the study. All study drugs were generally well tolerated and no subjects withdrew participation. The geometric mean ratio (90% confidence interval) for gemfibrozil area under the plasma concentration-time curve after 14 days of lopinavir-ritonavir compared with baseline was 0.59 (0.52, 0.67) (P < 0.001). All 15 study subjects experienced a reduction in gemfibrozil area under the plasma concentration-time curve after lopinavir-ritonavir (range, -6% to -74%). The geometric mean ratios for gemfibrozil apparent oral clearance and maximum concentration were 1.69 (1.41, 1.97) and 0.67 (0.49, 0.86) after 14 days of lopinavir-ritonavir versus baseline, respectively (P < 0.0001 and 0.01, respectively). Gemfibrozil elimination half-life did not change after lopinavir-ritonavir administration (P = 0.60). Conclusion:Lopinavir-ritonavir significantly reduced the systemic exposure of gemfibrozil by reducing gemfibrozil absorption. Clinicians treating HIV-infected patients with hypertriglyceridemia should be aware of this drug interaction.

Influence of Panax ginseng on the Steady State Pharmacokinetic Profile of Lopinavir-Ritonavir in Healthy Volunteers

Panax ginseng has been shown in preclinical studies to modulate cytochrome P450 enzymes involved in the metabolism of HIV protease inhibitors. Therefore, the purpose of this study was to determine the influence of P. ginseng on the pharmacokinetics of the HIV protease inhibitor combination lopinavir‐ritonavir (LPV‐r) in healthy volunteers.

The Effect of Intermittent IL-2 Therapy on CD4 T Cells in the Gut in HIV-1-Infected Patients

We sought to determine the effects of interleukin-2 administered in combination with antiretroviral therapy (ART) on CD4+ T cells in the gut. Lymphocytes from whole blood, colon, and terminal ileum of HIV-infected adults treated with interleukin-2 and ART or ART alone were examined. There were no differences between groups in the proportion of CD4+ T cells or in expression of CD25 or Ki67 by CD4+ T cells in the gut. Although IL-2 administration leads to expansion of peripheral blood CD4+ T cells, there is no alteration in the proportion or activation of CD4+ T cells in the gut mucosa.