Ma Somsouk

Comparative Analysis of Measures of Viral Reservoirs in HIV-1 Eradication Studies

HIV-1 reservoirs preclude virus eradication in patients receiving highly active antiretroviral therapy (HAART). The best characterized reservoir is a small, difficult-to-quantify pool of resting memory CD4+ T cells carrying latent but replication-competent viral genomes. Because strategies targeting this latent reservoir are now being tested in clinical trials, well-validated high-throughput assays that quantify this reservoir are urgently needed. Here we compare eleven different approaches for quantitating persistent HIV-1 in 30 patients on HAART, using the original viral outgrowth assay for resting CD4+ T cells carrying inducible, replication-competent viral genomes as a standard for comparison. PCR-based assays for cells containing HIV-1 DNA gave infected cell frequencies at least 2 logs higher than the viral outgrowth assay, even in subjects who started HAART during acute/early infection. This difference may reflect defective viral genomes. The ratio of infected cell frequencies determined by viral outgrowth and PCR-based assays varied dramatically between patients. Although strong correlations with the viral outgrowth assay could not be formally excluded for most assays, correlations achieved statistical significance only for integrated HIV-1 DNA in peripheral blood mononuclear cells and HIV-1 RNA/DNA ratio in rectal CD4+ T cells. Residual viremia was below the limit of detection in many subjects and did not correlate with the viral outgrowth assays. The dramatic differences in infected cell frequencies and the lack of a precise correlation between culture and PCR-based assays raise the possibility that the successful clearance of latently infected cells may be masked by a larger and variable pool of cells with defective proviruses. These defective proviruses are detected by PCR but may not be affected by reactivation strategies and may not require eradication to accomplish an effective cure. A molecular understanding of the discrepancy between infected cell frequencies measured by viral outgrowth versus PCR assays is an urgent priority in HIV-1 cure research.

Dysbiosis of the gut microbiota is associated with HIV disease progression and tryptophan catabolism.

Gut-resident microbial populations may influence intestinal homeostasis during HIV disease. Gut Reaction to HIV Despite the value placed on individuality in the western world, no human is an island. Indeed, every person carries trillions of microorganisms in their intestine, and it’s becoming increasingly clear that the composition and interaction of these microorganisms can directly affect human health. Vujkovic-Cvijin et al. now demonstrate that this is the case for individuals infected with HIV, even those where viral load is controlled by therapy. The authors screened the intestinal microbiome for microbial drivers of HIV-associated immunopathology. They found that a dysbiotic mucosal microbial community associated with mucosal immune disruption, T cell activation, and chronic inflammation in HIV-infected subjects, even in patients controlled with antiviral therapy. They then looked further into the mechanism of this association and found that the extent of dysbiosis correlated with tryptophan catabolism and plasma concentrations of the inflammatory cytokine interleukin-6 (IL-6), two established markers of disease progression. Indeed, gut-resident bacteria with the capacity to metabolize tryptophan were found to be enriched in HIV-infected subjects. These data link gut-resident microbial populations with the immunopathogenesis of HIV and suggest that modulating this community could provide a new therapeutic strategy for managing HIV disease progression. Progressive HIV infection is characterized by dysregulation of the intestinal immune barrier, translocation of immunostimulatory microbial products, and chronic systemic inflammation that is thought to drive progression of disease to AIDS. Elements of this pathologic process persist despite viral suppression during highly active antiretroviral therapy (HAART), and drivers of these phenomena remain poorly understood. Disrupted intestinal immunity can precipitate dysbiosis that induces chronic inflammation in the mucosa and periphery of mice. However, putative microbial drivers of HIV-associated immunopathology versus recovery have not been identified in humans. Using high-resolution bacterial community profiling, we identified a dysbiotic mucosal-adherent community enriched in Proteobacteria and depleted of Bacteroidia members that was associated with markers of mucosal immune disruption, T cell activation, and chronic inflammation in HIV-infected subjects. Furthermore, this dysbiosis was evident among HIV-infected subjects undergoing HAART, and the extent of dysbiosis correlated with activity of the kynurenine pathway of tryptophan catabolism and plasma concentrations of the inflammatory cytokine interleukin-6 (IL-6), two established markers of disease progression. Gut-resident bacteria with capacity to catabolize tryptophan through the kynurenine pathway were found to be enriched in HIV-infected subjects, strongly correlated with kynurenine levels in HIV-infected subjects, and capable of kynurenine production in vitro. These observations demonstrate a link between mucosal-adherent colonic bacteria and immunopathogenesis during progressive HIV infection that is apparent even in the setting of viral suppression during HAART. This link suggests that gut-resident microbial populations may influence intestinal homeostasis during HIV disease.

HIV-Infected Individuals with Low CD4/CD8 Ratio despite Effective Antiretroviral Therapy Exhibit Altered T Cell Subsets, Heightened CD8+ T Cell Activation, and Increased Risk of Non-AIDS Morbidity and Mortality

A low CD4/CD8 ratio in elderly HIV-uninfected adults is associated with increased morbidity and mortality. A subset of HIV-infected adults receiving effective antiretroviral therapy (ART) fails to normalize this ratio, even after they achieve normal CD4+ T cell counts. The immunologic and clinical characteristics of this clinical phenotype remain undefined. Using data from four distinct clinical cohorts and three clinical trials, we show that a low CD4/CD8 ratio in HIV-infected adults during otherwise effective ART (after CD4 count recovery above 500 cells/mm3) is associated with a number of immunological abnormalities, including a skewed T cell phenotype from naïve toward terminally differentiated CD8+ T cells, higher levels of CD8+ T cell activation (HLADR+CD38+) and senescence (CD28− and CD57+CD28−), and higher kynurenine/tryptophan ratio. Changes in the peripheral CD4/CD8 ratio are also reflective of changes in gut mucosa, but not in lymph nodes. In a longitudinal study, individuals who initiated ART within six months of infection had greater CD4/CD8 ratio increase compared to later initiators (>2 years). After controlling for age, gender, ART duration, nadir and CD4 count, the CD4/CD8 ratio predicted increased risk of morbidity and mortality. Hence, a persistently low CD4/CD8 ratio during otherwise effective ART is associated with increased innate and adaptive immune activation, an immunosenescent phenotype, and higher risk of morbidity/mortality. This ratio may prove useful in monitoring response to ART and could identify a unique subset of individuals needed of novel therapeutic interventions.

A Cost-Utility Analysis of Ablative Therapy for Barrett's Esophagus

BACKGROUND & AIMS Recommendations for patients with Barretts esophagus (BE) include endoscopic surveillance with esophagectomy for early-stage cancer, although new technologies to ablate dysplasia and metaplasia are available. This study compares the cost utility of ablation with that of endoscopic surveillance strategies. METHODS A decision analysis model was created to examine a population of patients with BE (mean age 50), with separate analyses for patients with no dysplasia, low-grade dysplasia (LGD), or high-grade dysplasia (HGD). Strategies compared were no endoscopic surveillance; endoscopic surveillance with ablation for incident dysplasia; immediate ablation followed by endoscopic surveillance in all patients or limited to patients in whom metaplasia persisted; and esophagectomy. Ablation modalities modeled included radiofrequency, argon plasma coagulation, multipolar electrocoagulation, and photodynamic therapy. RESULTS Endoscopic ablation for patients with HGD could increase life expectancy by 3 quality-adjusted years at an incremental cost of <

Activation, exhaustion, and persistent decline of the antimicrobial MR1-restricted MAIT-cell population in chronic HIV-1 infection

6,000 compared with no intervention. Patients with LGD or no dysplasia can also be optimally managed with ablation, but continued surveillance after eradication of metaplasia is expensive. If ablation permanently eradicates >or=28% of LGD or 40% of nondysplastic metaplasia, ablation would be preferred to surveillance. CONCLUSIONS Endoscopic ablation could be the preferred strategy for managing patients with BE with HGD. Ablation might also be preferred in subjects with LGD or no dysplasia, but the cost effectiveness depends on the long-term effectiveness of ablation and whether surveillance endoscopy can be discontinued after successful ablation. As further postablation data become available, the optimal management strategy will be clarified.

The HIV-1 reservoir in eight patients on long-term suppressive antiretroviral therapy is stable with few genetic changes over time

Mucosal-associated invariant T (MAIT) cells are an evolutionarily conserved antimicrobial MR1-restricted T-cell subset. MAIT cells are CD161(+), express a V7.2 TCR, are primarily CD8(+) and numerous in blood and mucosal tissues. However, their role in HIV-1 infection is unknown. In this study, we found levels of MAIT cells to be severely reduced in circulation in patients with chronic HIV-1 infection. Residual MAIT cells were highly activated and functionally exhausted. Their decline was associated with time since diagnosis, activation levels, and the concomitant expansion of a subset of functionally impaired CD161(+) V7.2(+) T cells. Such cells were generated in vitro by exposure of MAIT cells to Escherichia coli. Notably, whereas the function of residual MAIT cells was at least partly restored by effective antiretroviral therapy, levels of MAIT cells in peripheral blood were not restored. Interestingly, MAIT cells in rectal mucosa were relatively preserved, although some of the changes seen in blood were recapitulated in the mucosa. These findings are consistent with a model in which the MAIT-cell compartment, possibly as a result of persistent exposure to microbial material, is engaged, activated, exhausted, and progressively and persistently depleted during chronic HIV-1 infection.

Hepatitis C virus is independently associated with increased insulin resistance after liver transplantation.

Significance Identifying the source and dynamics of persistent HIV-1 during combinational antiretroviral therapy (cART) is crucial for understanding the barriers to curing HIV infection. Through genetic characterization of HIV-1 DNA in infected cells from peripheral blood and gut-associated lymphoid tissue from patients after long-term suppressive cART, our study reveals that the primary barrier to a cure is a remarkably stable pool of infected memory CD4+ T cells. Through in-depth phylogenetic analyses, we determined that the HIV-1 reservoir in these cells from eight patients is kept stable during long-term cART and, with little evidence of viral replication, this population could be maintained by homeostatic cell proliferation or other processes. The source and dynamics of persistent HIV-1 during long-term combinational antiretroviral therapy (cART) are critical to understanding the barriers to curing HIV-1 infection. To address this issue, we isolated and genetically characterized HIV-1 DNA from naïve and memory T cells from peripheral blood and gut-associated lymphoid tissue (GALT) from eight patients after 4–12 y of suppressive cART. Our detailed analysis of these eight patients indicates that persistent HIV-1 in peripheral blood and GALT is found primarily in memory CD4+ T cells [CD45RO+/CD27(+/−)]. The HIV-1 infection frequency of CD4+ T cells from peripheral blood and GALT was higher in patients who initiated treatment during chronic compared with acute/early infection, indicating that early initiation of therapy results in lower HIV-1 reservoir size in blood and gut. Phylogenetic analysis revealed an HIV-1 genetic change between RNA sequences isolated before initiation of cART and intracellular HIV-1 sequences from the T-cell subsets after 4–12 y of suppressive cART in four of the eight patients. However, evolutionary rate analyses estimated no greater than three nucleotide substitutions per gene region analyzed during all of the 4–12 y of suppressive therapy. We also identified a clearly replication-incompetent viral sequence in multiple memory T cells in one patient, strongly supporting asynchronous cell replication of a cell containing integrated HIV-1 DNA as the source. This study indicates that persistence of a remarkably stable population of infected memory cells will be the primary barrier to a cure, and, with little evidence of viral replication, this population could be maintained by homeostatic cell proliferation or other processes.

The immunologic effects of maraviroc intensification in treated HIV-infected individuals with incomplete CD4+ T-cell recovery: a randomized trial.

Background and Aims. There is a strong epidemiologic association between diabetes mellitus (DM) and hepatitis C virus (HCV) infection. However, the pathogenetic basis for this association has not been established. We sought to evaluate the association between insulin resistance (IR), &bgr;-cell dysfunction, and HCV among orthotopic liver transplant (OLT) recipients. Methods. We performed a cross sectional analysis comparing 39 HCV(+) with 60 HCV(−) OLT recipients. IR and &bgr;-cell function were calculated using validated measures and were correlated with clinical variables. Results. By multivariate analysis of the entire cohort, HCV infection and body mass index (BMI) were independent predictors of IR (P =0.04 and 0.0006, respectively). HCV infection was associated with 35% increase in IR. Because the model used to calculate IR was derived from nondiabetic subjects, we performed additional analysis of patients who did not meet criteria for diabetes at the time of their study evaluation. In this analysis, HCV(+) subjects had greater fasting insulin and homeostasis model assessment (HOMA) IR (15.3 &mgr; U/mL and 3.8) compared with HCV(−) patients (10.7 &mgr; U/mL and 2.5) (P =0.03, 0.03). There was no difference in &bgr;-cell function or hepatic insulin extraction between the HCV (+) and (−) groups. HCV (P =0.0005), BMI (P <0.0001), and high high-density lipoprotein (P =0.039) were the only independent predictors of IR. The presence of HCV infection and a 10-fold increase in HCV RNA were associated with a 62% and 8% increase in IR, respectively. Conclusions. HCV is independently associated with increased IR after OLT. These findings provide a possible pathogenetic basis for the association of DM with HCV.

Adverse events in older patients undergoing colonoscopy: a systematic review and meta-analysis

The CCR5 inhibitor maraviroc has been hypothesized to decrease T-cell activation in HIV-infected individuals, but its independent immunologic effects have not been established in a placebo-controlled trial. We randomized 45 HIV-infected subjects with CD4 counts <350 cells per mm(3) and plasma HIV RNA levels <48 copies per mL on antiretroviral therapy (ART) to add maraviroc vs placebo to their regimen for 24 weeks followed by 12 weeks on ART alone. Compared with placebo-treated subjects, maraviroc-treated subjects unexpectedly experienced a greater median increase in % CD38+HLA-DR+ peripheral blood CD8+ T cells at week 24 (+2.2% vs -0.7%, P = .014), and less of a decline in activated CD4+ T cells (P < .001). The % CD38+HLA-DR+ CD4+ and CD8+ T cells increased nearly twofold in rectal tissue (both P < .001), and plasma CC chemokine receptor type 5 (CCR5) ligand (macrophage-inflammatory protein 1β) levels increased 2.4-fold during maraviroc intensification (P < .001). During maraviroc intensification, plasma lipopolysaccharide declined, whereas sCD14 levels and neutrophils tended to increase in blood and rectal tissue. Although the mechanisms explaining these findings remain unclear, CCR5 ligand-mediated activation of T cells, macrophages, and neutrophils via alternative chemokine receptors should be explored. These results may have relevance for trials of maraviroc for HIV preexposure prophylaxis and graft-versus-host disease. This trial was registered at www.clinicaltrials.gov as #NCT00735072.

Increased Frequency of Regulatory T Cells Accompanies Increased Immune Activation in Rectal Mucosae of HIV-Positive Noncontrollers

BACKGROUND Studies suggest that advancing age is an independent risk factor for experiencing adverse events during colonoscopy. Yet many of these studies are limited by small sample sizes and/or marked variation in reported outcomes. OBJECTIVE To determine the incidence rates for specific adverse events in elderly patients undergoing colonoscopy and calculate incidence rate ratios for selected comparison groups. SETTING AND PATIENTS Elderly patients undergoing colonoscopy. DESIGN Systematic review and meta-analysis. MAIN OUTCOME MEASUREMENTS Perforation, bleeding, cardiovascular (CV)/pulmonary complications, and mortality. RESULTS Our literature search yielded 3328 articles, of which 20 studies met our inclusion criteria. Pooled incidence rates for adverse events (per 1000 colonoscopies) in patients 65 years of age and older were 26.0 (95% CI, 25.0-27.0) for cumulative GI adverse events, 1.0 (95% CI, 0.9-1.5) for perforation, 6.3 (95% CI, 5.7-7.0) for GI bleeding, 19.1 (95% CI, 18.0-20.3) for CV/pulmonary complications, and 1.0 (95% CI, 0.7-2.2) for mortality. Among octogenarians, adverse events (per 1000 colonoscopies) were as follows: cumulative GI adverse event rate of 34.9 (95% CI, 31.9-38.0), perforation rate of 1.5 (95% CI, 1.1-1.9), GI bleeding rate of 2.4 (95% CI, 1.1-4.6), CV/pulmonary complication rate of 28.9 (95% CI, 26.2-31.8), and mortality rate of 0.5 (95% CI, 0.06-1.9). Patients 80 years of age and older experienced higher rates of cumulative GI adverse events (incidence rate ratio 1.7; 95% CI, 1.5-1.9) and had a greater risk of perforation (incidence rate ratio 1.6, 95% CI, 1.2-2.1) compared with younger patients (younger than 80 years of age). There was an increased trend toward higher rates of GI bleeding and CV/pulmonary complications in octogenarians but neither was statistically significant. LIMITATIONS Heterogeneity of studies included and not all complications related to colonoscopy were captured. CONCLUSIONS Elderly patients, especially octogenarians, appear to have a higher risk of complications during and after colonoscopy. These data should inform clinical decision making, the consent process, public health policy, and comparative effectiveness analyses.