Declines in Lung Function After Antiretroviral Therapy Initiation in Adults With Human Immunodeficiency Virus and Tuberculosis: A Potential Manifestation of Respiratory Immune Reconstitution Inflammatory Syndrome

End-organ impairment has received relatively little research attention as a possible manifestation of tuberculosis immune reconstitution inflammatory syndrome (TB-IRIS). In this prospective cohort study, one-half of adults with human immunodeficiency virus and pulmonary tuberculosis experienced meaningful declines in lung function on antiretroviral therapy, suggesting a role for lung function in TB-IRIS definitions

Comparing the performance of QuantiFERON-TB Gold Plus with QuantiFERON-TB Gold in-tube among highly TB exposed gold miners in South Africa

Background: QuantiFERON-TB-Gold-in-tube (QFT-GIT) is an interferon-gamma release assay (IGRA) used to diagnose latent tuberculosis infection. Limited data exists on performance of QuantiFERON-TB Gold-Plus (QFT-Plus), a next generation of IGRA that includes an additional antigen tube 2 (TB2) while excluding TB7.7 from antigen tube 1 (TB1), to measure TB specific CD4+ and CD8+ T lymphocytes responses. We compared the performance of QFT-Plus with QFT-GIT among highly TB exposed goldminers in South Africa. Methods: We enrolled HIV-negative goldminers in South Africa, aged ≥33 years with no prior history of TB disease or evidence of silicosis. Blood samples were collected for QFT-GIT and QFT-Plus. QFT-GIT was considered positive if TB1 tested positive; while QFT-Plus was positive if both or either TB1 or TB2 tested positive, as per manufacturer's recommendations. We compared the performance of QFT-Plus with QFT-GIT using Cohen’s Kappa. To assess the specific contribution of CD8+ T-cells, we used TB2−TB1 differential values as an indirect estimate. A cut-off value was set at 0.6. Logistic regression was used to identify factors associated with having TB2-TB1&gt;0.6 difference on QFT-Plus. Results: Of 349 enrolled participants, 304 had QFT-Plus and QFT-GIT results: 205 (68%) were positive on both assays; 83 (27%) were negative on both assays while 16 (5%) had discordant results. Overall, there was 94.7% (288/304) agreement between QFT-Plus and QFT-GIT (Kappa = 0.87). 214 had positive QFT-Plus result, of whom 202 [94.4%, median interquartile range (IQR): 3.06 (1.31, 7.00)] were positive on TB1 and 205 [95.8%, median (IQR): 3.25 (1.53, 8.02)] were positive on TB2. A TB2-TB1&gt;0.6 difference was observed in 16.4% (35/214), with some evidence of a difference by BMI; 14.9% (7/47), 9.8% (9/92) and 25.3% (19/75) for BMI of 18.5-24.9, 18.5-25 and &gt;30 kg/m2, respectively (P=0.03). Conclusion: In a population of HIV-negative goldminers, QFT-Plus showed high agreement with QFT-GIT, suggesting similar performance.</ns3:p

Comparing QuantiFERON-TB Gold Plus with QuantiFERON-TB Gold in-tube for diagnosis of latent tuberculosis infection among highly TB exposed gold miners in South Africa.

BACKGROUND: QuantiFERON-TB-Gold-in-tube (QFT-GIT) is an interferon-gamma release assay (IGRA) used to diagnose latent tuberculosis infection. Limited data exists on performance of QuantiFERON-TB Gold-Plus (QFT-Plus), a next generation of IGRA that includes an additional antigen tube 2 (TB2) while excluding TB7.7 from antigen tube 1 (TB1), to measure TB specific CD4+ and CD8+ T lymphocytes responses. We compared agreement between QFT-Plus and QFT-GIT among highly TB exposed goldminers in South Africa. METHODS: We enrolled HIV-negative goldminers in South Africa, aged ≥33 years with no prior history of TB disease or evidence of silicosis. Blood samples were collected for QFT-GIT and QFT-Plus. QFT-GIT was considered positive if TB1 tested positive; while QFT-Plus was positive if both or either TB1 or TB2 tested positive, as per manufacturer's recommendations. We compared the agreement between QFT-Plus and QFT-GIT using Cohen’s Kappa. To assess the specific contribution of CD8+ T-cells, we used TB2−TB1 differential values as an indirect estimate. A cut-off value was set at 0.6. Logistic regression was used to identify factors associated with having TB2-TB1>0.6 difference on QFT-Plus. RESULTS: Of 349 enrolled participants, 304 had QFT-Plus and QFT-GIT results: 205 (68%) were positive on both assays; 83 (27%) were negative on both assays while 16 (5%) had discordant results. Overall, there was 94.7% (288/304) agreement between QFT-Plus and QFT-GIT (Kappa = 0.87). 214 had positive QFT-Plus result, of whom 202 [94.4%, median interquartile range (IQR): 3.06 (1.31, 7.00)] were positive on TB1 and 205 [95.8%, median (IQR): 3.25 (1.53, 8.02)] were positive on TB2. A TB2-TB1>0.6 difference was observed in 16.4% (35/214), with some evidence of a difference by BMI; 14.9% (7/47), 9.8% (9/92) and 25.3% (19/75) for BMI of 18.5-24.9, 18.5-25 and >30 kg/m 2, respectively (P=0.03). CONCLUSION: In a population of HIV-negative goldminers, QFT-Plus showed high agreement with QFT-GIT, suggesting similar performance

Association of HIV-Specific and Total CD8+ T Memory Phenotypes in Subtype C HIV-1 Infection with Viral Set Point.

Understanding early immunological events during HIV-1 infection that may set the course of disease progression is important for identifying correlates of viral control. This study explores the association of differentiation profiles of HIV-specific and total memory CD8+ T cells with viral set point. A cohort of 47 HIV-1-infected individuals, with differing viral set points at 12 mo, were recruited during acute infection. We identified that the magnitude of IFN-γ+ T cell responses at 6 mo postinfection did not associate with viral set point at 12 mo. A subset of 16 individuals was further studied to characterize CD8+ T cells for expression patterns of markers for memory differentiation, survival (CD127), senescence (CD57), and negative regulation (programmed death-1). We show that viral control and the predicted tempo of HIV disease progression in the first year of infection was associated with a synchronous differentiation of HIV-specific and total CD8+ memory subpopulations. At 6–9 mo postinfection, those with low viral set points had a significantly higher proportion of early differentiated HIV-specific and total memory CD8+ cells of a central memory (CD45RO+CD27+CCR7+) and intermediate memory (CD45RO−CD27+CCR7−) phenotype. Those with high viral set points possessed significantly larger frequencies of effector memory (CD45RO+CD27−CCR7−) cells. The proportions of memory subsets significantly correlated with CD38+CD8+ T cells. Thus, it is likely that a high Ag burden resulting in generalized immune activation may drive differentiation of HIV-specific and total memory CD8+ T cells

Monocyte metabolic transcriptional programs associate with resistance to tuberculin skin test/interferon-γ release assay conversion.

After extensive exposure to Mycobacterium tuberculosis (Mtb), most individuals acquire latent Mtb infection (LTBI) defined by a positive tuberculin skin test (TST) or interferon-γ release assay (IGRA). To identify mechanisms of resistance to Mtb infection, we compared transcriptional profiles from highly exposed contacts who resist TST/IGRA conversion (resisters, RSTRs) and controls with LTBI using RNAseq. Gene sets related to carbon metabolism and free fatty acid (FFA) transcriptional responses enriched across 2 independent cohorts suggesting RSTR and LTBI monocytes have distinct activation states. We compared intracellular Mtb replication in macrophages treated with FFAs and found that palmitic acid (PA), but not oleic acid (OA), enhanced Mtb intracellular growth. This PA activity correlated with its inhibition of proinflammatory cytokines in Mtb-infected cells. Mtb growth restriction in PA-treated macrophages was restored by activation of AMP kinase (AMPK), a central host metabolic regulator known to be inhibited by PA. Finally, we genotyped AMPK variants and found 7 SNPs in PRKAG2, which encodes the AMPK-γ subunit, that strongly associated with RSTR status. Taken together, RSTR and LTBI phenotypes are distinguished by FFA transcriptional programs and by genetic variation in a central metabolic regulator, which suggests immunometabolic pathways regulate TST/IGRA conversion

Control of the HIV-1 Load Varies by Viral Subtype in a Large Cohort of African Adults With Incident HIV-1 Infection.

Few human immunodeficiency virus (HIV)-infected persons can maintain low viral levels without therapeutic intervention. We evaluate predictors of spontaneous control of the viral load (hereafter, "viral control") in a prospective cohort of African adults shortly after HIV infection. Viral control was defined as ≥2 consecutively measured viral loads (VLs) of ≤10 000 copies/mL after the estimated date of infection, followed by at least 4 subsequent measurements for which the VL in at least 75% was ≤10 000 copies/mL in the absence of ART. Multivariable logistic regression characterized predictors of viral control. Of 590 eligible volunteers, 107 (18.1%) experienced viral control, of whom 25 (4.2%) maintained a VL of 51-2000 copies/mL, and 5 (0.8%) sustained a VL of ≤50 copies/mL. The median ART-free follow-up time was 3.3 years (range, 0.3-9.7 years). Factors independently associated with control were HIV-1 subtype A (reference, subtype C; adjusted odds ratio [aOR], 2.1 [95% confidence interval {CI}, 1.3-3.5]), female sex (reference, male sex; aOR, 1.8 [95% CI, 1.1-2.8]), and having HLA class I variant allele B*57 (reference, not having this allele; aOR, 1.9 [95% CI, 1.0-3.6]) in a multivariable model that also controlled for age at the time of infection and baseline CD4+ T-cell count. We observed strong associations between infecting HIV-1 subtype, HLA type, and sex on viral control in this cohort. HIV-1 subtype is important to consider when testing and designing new therapeutic and prevention technologies, including vaccines

An investigation of fungi and mycotoxins in barley grain and materials used for brewing

M.F. Dutto

Activation and memory differentiation of total and HIV-specific T cells that associate with viral control during subtype C HIV-1 infection

Thesis (Ph.D.)--University of the Witwatersrand, Faculty of Health Sciences, 2012.The development of an effective HIV-1 vaccine is critical in mitigating the global HIV epidemic. Understanding the interplay between host immune functions, such as cellular memory differentiation, activation, inflammatory cytokine production and the virus, may provide key insight into anti-HIV immunity that can inform vaccine development. This PhD aims at understanding and identifying T cell memory, functional profiles and the effect of immune activation on in vivo HIV-1 control during primary/early infection. Furthermore, this study aims to examine and understand the potential mechanisms related to immune activation during primary HIV-1 infection. Use was made of a unique cohort of individuals recruited during primary HIV-1 infection and using a battery of assays to characterize and identify properties and mechanisms of T cell reactivity and activation. Multiparameter flow cytometry was used to measure memory differentiation (CD27 and CD45RO), activation (CD38, HLA-DR), proliferation (Ki67), and multiple cellular functions (CD107, IFNγ, IL-2, MIP-1β and TNFα) of total and antigen-specific CD4+ and CD8+ T cells from 15 HIV-1 and CMV-coinfected individuals followed over 15 months of HIV-1 infection. Plasma samples were used to measure markers associated with intestinal permeability (LBP, sCD14, I-FABP and IgM EndoCAb) and inflammation (IL-1β, IL-6, IL-7, IL-10, IL-12p70, TNFα and MCP-1). The differentiation profile of HIV-Gag specific memory CD4+ and CD8+ T cells was found to be mainly characterized by an early differentiated (ED) memory phenotype relative to CMV- specific CD4+ and CD8+ T cells. Moreover, the proportion of HIV-specific ED-memory CD4+ T cells inversely associated with viraemia, suggesting that HIV-1 antigen burden could be shaping the differentiation of HIV-specific memory CD4+ T cells during primary infection. Primary HIV-1 infection was also characterized by significantly elevated levels of activated and proliferating total and HIV-specific memory CD4+ and CD8+ T cells, which positively correlated with viraemia. Furthermore, upon sorting of total activated memory CD4+ T cells, these cells harboured more gag provirus DNA than non-activated memory cells, suggesting that activated memory CD4+ T cells support ongoing HIV-1 replication. When examining the relationship between memory differentiation and activation markers, the level of T cell activation was equally expanded across the different memory CD4+ T cell subpopulations, suggesting that memory differentiation of CD4+ T cells was unlikely driven per se by the level of T cell activation. In addition, when teasing out events that may result in T cell activation during primary HIV-1 infection using statistical models, plasma markers of microbial translocation and inflammation were found to correlate with immune activation. The lack of these associations in HIV-uninfected controls suggests that microbial translocation and inflammation were unlikely causative. Analysis of the polyfunctional profile of memory T cells during primary HIV-1 infection showed that HIV-specific CD4+ and CD8+ T cell responses are less polyfunctional relative to CMV-specific memory CD4+ and CD8+ T cell responses. Furthermore, the polyfunctional status of HIV-specific CD4+ T cells significantly correlated with viraemia at 3 months post-infection, indicating that the polyfunctionality of memory CD4+ T cells is likely driven by HIV-1 antigenemia. Overall, these observations suggest that HIV-1 antigenic burden appears to be a central driver of memory differentiation, activation/inflammation and polyfunctionality of T cells. Given the impact of HIV-1 viraemia on immune activation and memory T cell dysfunction (as measured by limited polyfunctional HIV-specific responses), preventing high levels of viral replication, with a vaccine or other early interventions may serve as an important strategy for delaying HIV-1 disease progression

The Use of Isolated Human Lymphocytes in Mycotoxin Cytotoxicity Testing

The cytotoxicity of selected mycotoxins against isolated human lymphocytes was investigated, as a means of detecting mycotoxins in extracts derived from cereal samples. The methodology was based on the ability of viable cells to reduce methyl tetrazolium bromide to a purple formazan dye that could be quantitated by spectrophometric means and hence give a measure of the cytotoxicity of added substances. The results showed that there was good correlation with the occurrence of identified mycotoxins with only a minimum of false positives. For example, of the 13 samples of barley or barley derivatives that were positive for the mycotoxins, fumonisin B1 (FB1) deoxynivalenol (DON) and ochratoxin A (OTA), all gave positive cytotoxicity responses. Two samples negative for mycotoxins gave no cytotoxicity responses. There was little variation between the results for lymphocytes drawn from the same healthy volunteer on three different occasions. Furthermore, for two of the mycotoxins tested (FB1 and DON) it was possible to correlate general levels of mycotoxins present to the cytotoxic response of the lymphocytes but not for OTA, where it was concluded that interfering substances prevented direct correlation. It was concluded that this method was suited for general application as it could handle relatively high number of samples in a short period of time