Tuberculosis (TB) is a global health problem and there is an urgent need for the development of new therapeutics and biomarkers to combat this disease. microRNAs (miRNAs) have been recently discovered to play critical roles in immunological and pathological processes. The high stability of miRNAs in human plasma also makes them an attractive biomarker. Human macrophages infected with M. tuberculosis showed marked changes in macrophage activation and expression of multiple miRNAs. The expression of miRNA levels in plasma was then measured to determine if modulation of miRNAs could be used as a biomarker of TB infection.
The expression of 175 miRNAs was determined in a test group of 20 TB patients and 20 healthy controls. 10 miRNAs that were significantly different between these groups were then examined in 100 TB patients and matched healthy controls at baseline, prior to the commencement of treatment and after 1, 2 and 6 months antibiotic therapy in the TB subjects.
A number of miRs were significantly different between the TB patients compared with control subjects at time 0. Furthermore in TB patients who responded to therapy, there was a reduction in mean difference between the two groups, indicating that the miRNA levels were trending back to the baseline levels seen in the healthy controls. These data indicate that M. tuberculosis infection modulates miRNA expression, and these changes have biomarker potential to identify individuals with active TB disease and monitor their response to therapy.