Researchers from Mumbai in November 2016 identified two biomarkers in serum samples that could help in TB diagnosis and TB disease prognosis. The identified microRNA biomarkers could be used for drug-sensitive pulmonary TB and multi-drug resistant TB (MDR-TB) patients.
Details about the study:
• The research covered measuring of the levels of 4 miRNAs – miR-16, miR-29a, miR-125b and miR-155 in 30 newly diagnosed TB patients, 19 Multi Drug Resistant (MDR TB) patients and 10 patients who completed their therapy and were cured of the disease. 30 healthy individuals were also recruited as controls.
• The levels of miRNAs were estimated by qRT-PCR (Reverse transcription polymerase chain reaction), a technique used in molecular biology to detect RNA expression.
• Among the 4 miRNAs studied, levels of miR-16 showed to be significantly higher and miR-155 significantly lower in the serum of TB patients in comparison to healthy individuals.
• Serum samples collected from the 10 cured patients were also tested for two microRNAs- miR-16 and miR- 155, both at the time of diagnosis as well as after the conclusion of the treatment.
• The levels of both the biomarkers are different in people with MDR- TB in comparison with those who are healthy and those suffering from drug-sensitive pulmonary TB:
1. miR- 16 is 5-6 times higher in the patients with drug-sensitive TB and 2 times lower than normal level in patients with MDR-TB.
2. In case of miR-155, the reduction is only slightly less in comparison with drug sensitive TB and yet higher than the normal level. Both levels returned to normal once the treatment was complete.
Which is a better indicator: miR-16 or miR-155?
miR-16 shows a better predictive value than miR-155 in both drug-sensitive pulmonary TB and MDR-TB cases.
Why this discovery is path-breaking for TB Diagnosis?
• Tuberculosis patients in India are generally first treated with drug sensitive TB drugs and it is only when they do not show any sign of improvement despite months of medication that MDR-TB is suspected.
• The use of these biomarkers may accelerate the diagnosis of MDR-TB.
• If miR-16 level is revealed to be lower than normal in case of TB patients or miR-155 level is not found to be increasing then, MDR-TB should be suspected.