Gene Expression in HIV and Tuberculosis Co-infection

Tuberculosis (TB) remains one of the deadliest infections throughout the world, particularly in the setting of HIV infection. In China, TB is a frequently diagnosed complication of HIV infection. The immunopathogenesis of TB remains unclear, and although it is known that HIV infection increases the risk of developing active TB, either through infection or reactivation of latent disease, how it does so has yet to be determined. It is also known that patients co-infected with HIV and TB and na ve to antiretroviral therapy (ART) have a particularly high risk of developing Immune Reconstitution Inflammatory Syndrome (IRIS) after ART therapy is initiated, but the immunopathogenesis of this reaction is also unclear. The use of genomics has significantly improved the understanding of disease pathogenesis and is increasingly being used to predict responses to therapy as well. Recently, blood transcriptional signatures capable of distinguishing active and latent TB infection have been identified using highly parallelized analytical platforms capable of simultaneous survey of transcription of known genes. These signatures have hinted at a complex role for type I interferons in the development of active TB infection, but this has not yet been studied in people with HIV and TB co-infection. Further in depth studies are needed to characterize the spectrum of responses to TB/HIV co-infection, and how these responses correlate with clinical data. We propose a cross-sectional cohort study, to be conducted in both the US and in China, to identify blood mRNA expression profiles distinguishing TB mono-infected and TB/HIV co-infected ART-na ve patients from treated patients with and without TB-IRIS. Secondary objectives will include correlating gene expression levels with clinical outcomes and soluble biomarkers. The study will comprise a test set (in China) of 110 patients divided among the different cohorts and a validation set (in the US) of approximately 50 patients divided among the three groups. Participation will involve a single study visit to consist of small volume phlebotomy (approximately 25 mL for safety labs, transcriptome analysis, lymphocyte counts, and plasma storage) and information gleaned from the clinical record entered into a coded Case Report Form (CRF). The study will exclude persons who cannot provide informed consent, women who are pregnant or breast-feeding (which can be associated with immune compromise and changes in markers associated with inflammation), and persons with anemia (who may be unable to tolerate phlebotomy solely for research purposes).