Possible role of plasma Galectin-9 levels as a surrogate marker of viremia in HIV infected patients on antiretroviral therapy in resource-limited settings.

BACKGROUND: Early detection of viremia in HIV infected patients on anti-retroviral therapy (ART) is important to prevent disease progression as well as accumulation of drug resistance mutations. This makes HIV viral load (VL) monitoring indispensable in HIV infected patients on ART. However VL, being an expensive test, results in heavy financial burden on health services. Hence, cheaper surrogate markers of viremia are desired to reduce overall cost of management of HIV infected patients. METHODS: We enrolled aviremic (n = 63, M:F = 31:32) and viremic (n = 43, M:F = 21:22) HIV infected patients at 1 year after ART initiation. Viremic individuals were identified as those having a plasma VL of more than 1000 copies/µl and aviremic individuals as less than 40 copies/µl. The study participants also included immuno-virologically discordant patients as they demonstrate differential degrees of immune-reconstitution and are likely to harbour concomitant infections influencing levels of immune-activation markers screened as the surrogate markers. Immune activation markers viz. plasma hs-CRP, soluble-CD14 and Galectin-9 levels were estimated by ELISA, IL-6 by luminex assay and percentages of CD38+ CD8+ cells were determined by flow cytometry. The levels were compared between viremic and aviremic patients and correlated with plasma viral load. Receiver operated curve (ROC) analysis was done for plasma Galectin-9 levels. RESULTS: Viremic patients had significantly higher levels of Galectin-9 and %CD38+ CD8+ cells (p values < 0.0001) than aviremic patients. Levels of the other activation markers did not differ between viremic and aviremic individuals. Galectin-9 levels (r = 0.76) and %CD38+ CD8+ cells (r = 0.39) correlated positively with VL. Area under curve for Galectin-9 levels for distinguishing between viremic and aviremic individuals was 0.98. Youden index, sensitivity, specificity, positive predictive value and negative predictive value for Galectin-9 levels were 0.87, 0.97, 0.90, 0.87 and 0.98, respectively, at the cut-off value of 5.79 ng/ml. CONCLUSIONS: Plasma Galectin-9 levels could identify viremic individuals with sensitivity and specificity of more than 90%. Thus, they showed a potential to serve as a surrogate marker of viremia in HIV infected patients on ART and would have cost implications on HIV management especially in resource-limited settings. However, the findings need to be confirmed in the patients on ART for different durations of time.

High IL-5 levels possibly contributing to HIV viremia in virologic non-responders at one year after initiation of anti-retroviral therapy.

Lack of viral monitoring in HIV infected patients on anti-retroviral therapy in low income countries may result in missing virologic non-responders (VNR) who show immunologic recovery in spite of unsuppressed viral replication. Biomarkers and drug resistance patterns in these discordant patients in comparison to the concordant treatment failure group need to be studied to understand possible risk factors associated with this condition. HIV infected patients on anti-retroviral therapy for one year were enrolled under three categories namely VNRs (n = 25), treatment failures (n = 18) and treatment responders (n = 40). They were assessed for HIV drug resistance by sequencing, plasma cytokines by luminex assay, T cell activation status by flow cytometry and total IgE levels by ELISA. VNR and failure patients had significantly lower median baseline CD4 counts than the responders. VNRs had significantly higher CD4 counts but lower viral load than treatment failures at one year of ART. VNRs had the highest eosinophil counts and the highest IL-5 levels among all the groups. IL-5 levels in them correlated with their viral load values. Frequency of Treg cells was also highest among the VNR group participants. More than 60% of the viremic patients irrespective of their groups harboured multiple HIV drug resistance mutations and mutation pattern did not differ between the groups. Low baseline CD4 counts and presence of multiple drug resistance mutations in the viremic groups highlighted the importance of early ART initiation and viral load monitoring irrespective of presence of immunologic failure. High IL-5 levels in VNR group indicated a need for investigating causal relationship between IL-5 and viral replication to devise therapeutic strategies to control viremia.

Incomplete functional T-cell reconstitution in immunological non-responders at one year after initiation of antiretroviral therapy possibly predisposes them to infectious diseases.

BACKGROUND: Immunological non-responders (INR) represent a unique category of HIV-infected patients on antiretroviral therapy. These patients have suppressed viremia but a suboptimal increase in CD4 cell count, which might have opposing effects on functional immune reconstitution. Hence, the extent of immune reconstitution in INR patients was investigated in order to determine their susceptibility to opportunistic infections. METHODS: Twenty-three INR patients (CD4 increase <50 cells/mm3, viral load <40 copies/ml), 40 age-, sex-, and baseline CD4 count-matched responders (CD4 increase >100 cells/mm3, viral load <40 copies/ml), and 18 treatment failures defined as per the national guidelines were enrolled at 1year of antiretroviral therapy. The following examinations were performed: haemogram, phenotypic characterization by flow cytometry, and assessment of functional immune status by ELISPOT and intracellular cytokine assays. RESULTS: A higher percentage of INR patients had clinically symptomatic infections than the responders. CD8+ activation and innate immune parameters, including the absolute neutrophil count and natural killer (NK) cell frequency and functionality, were restored in the INR patients. They had significantly higher non-HIV antigen-specific T-cell responses and activated CD4+ cells, but significantly compromised T-cell functionality, as assessed after anti-CD3 stimulation, and lower CD31+ and CD62L+CD4+ cells. CONCLUSIONS: INR patients showed lower thymic output, incomplete functional T-cell reconstitution, higher responses to HIV co-pathogens, and higher symptomatic events, indicating the need for close monitoring and intervention strategies to overcome their continuing immunocompromised status.