Epigenetics and Proteomics join Transcriptomics on the quest towards TB Biomarkers

Even though recent reports estimate a reduction in the spread and contraction of Tuberculosis (TB), 30 % of the world population are currently being latently infected by Mycobacterium tuberculosis (Mtb). This latent infection can at any time develop into active disease. Biomarkers to monitor this process as well as biomarkers for disease susceptibility and TB diagnosis is urgently needed in order to facilitate a more drastic decrease in the spread of Mtb and better care for TB patients. Our understanding of biology combined with evolving technical advances in high-throughput techniques, led us to investigate the possibility of additional role players (epigenetics and proteomics) in the quest to (a) understand the biology of TB host response and (b) search for biomarkers in TB diagnostics and –susceptibility. We engaged in a pilot study, using a relatively small sample set to interrogate the DNA methylome, transcriptome and proteome in monocytes and granulocytes of TB patients and healthy latently infected participants. The observations in this study provide a first glimpse at the level- and sources of diversity in the epigenome and proteome amongst TB patients and latently infected controls despite limitations due to small sample size. Functionally the differences between the disease phenotypes observed in the different platforms were congruent and suggest regulation of function not only at the transcriptional level, but also by DNA methylation and microRNA. We conclude that the current data support the notion to develop a large scale study of especially the DNA methylome while care should be taken in the study design to account for variation based on gender, age and cell type.