Temporal Expression of Peripheral Blood Leukocyte Biomarkers in a Macaca fascicularis Primary Infection Model of Tuberculosis

A temporal study of gene expression in peripheral blood leukocytes (PBLs) from a Mycobacterium tuberculosis primary, temporal pulmonary challenge model Macaca fascicularis has been conducted. PBL samples were taken prior to challenge and at one, two, four an six weeks post-challenge and labelled, purified RNAs hybridised to Operon Human Genome AROS V4.0 slides. Data analyses revealed a large number of differentially regulated gene entities, which exhibited temporal profiles of expression across the time course study. Further data refinements identified key groups of markers showing specific group-specific expression patterns, with a substantial reprogramming event evident at the four to six week interval. Select statistically-significant gene entities from this study and other immune and apoptotic markers were validated using qPCR. These confirmed many of the observations elucidated using microarray hybridisation. The results showed evidence of a step-change from an ‘early’ perhaps FOS-driven response, to a predominantly type I interferon-driven response, with coincident reduction of expression of other markers i.e. loss of T-cell-associate marker expression in responsive animals and elevation of markers which may be associated with a myeloid suppressor cell phenotype e.g. CD163. The animals in the study were of different lineages, Chinese and Mauritian, which showed clear evidence of differing susceptibilities to Tuberculosis challenge. Further analyses determined a number of key differences in response profiles between the groups, particularly in expression of T-cell and apoptotic makers, among others. These have provided interesting insights into innate susceptibility phenotypes. Using a combination of parametric and non-parametric artificial neural network analyses we have identified key genes and regulatory pathways which may be important in earl and adaptive responses to TB. Six animals infected with Mycobacterium tuberculosis subsequent to prebleed timepoint; blood samples taken at defined weekly timepoints post-infection