Effect of Chinese herbal medicine extracts on cell-mediated immunity in a rat model of tuberculosis induced by multiple drug-resistant bacilli

Drug-resistant Mycobacterium tuberculosis poses a major threat to public health. The present study aimed to investigate the effects of Radix Ranunculi Ternati, Radix Sophorae Flavescentis, Prunella Vulgaris L. and Stellera Chamaejasme L. extracts on cell-mediated immunity in a rat model of tuberculosis (TB) induced by multiple drug-resistant bacilli. The bacterium was isolated from patients infected with pulmonary tuberculosis. The immunological response in humans following infection with Mycobacterium tuberculosis involves a number of cytokines, including IFN-gamma and IFN-alpha, which are important for killing intracellular micro-organisms. T helper type 2 (Th2) cells express numerous cytokines, including IL-4 and IL-10, which mainly participate in humoral immunity and induce the phagocytosis of extracellular bacteria and parasites. In the present study, rats were infected with multiple drug-resistant TB (MDR-TB) in order to establish an MDR-TB model. Peripheral blood mononuclear cells (PBMCs) were isolated and cultivated, and the serum levels Of IFN-gamma, IL-4, IL-10 and IL-12 were examined by ELISA. The mRNA expression levels of certain cytokines in PBMCs were additionally detected using RT-PCR. The serum levels of IFN-gamma in the Radix Ranunculi Ternati, Radix Sophorae Flavescentis, Prunella Vulgaris L. and Stellera Chamaejasme L. groups were 2.01 +/- 0.73, 1.92 +/- 0.56, 1.98 +/- 0.67 and 1.94 +/- 0.59 pg/ml; IL-4 levels were 6.01 +/- 1.46, 6.12 +/- 1.35, 6.47 +/- 1.46 and 6.15 +/- 1.44 pg/ml; IL-10 levels were 12.09 +/- 3.07, 12.45 +/- 4.01, 12.13 +/- 3.43 and 12.54 +/- 3.78 pg/ml; and IL-12 levels were 2.99 +/- 0.89, 2.75 +/- 0.84, 3.02 +/- 0.86 and 2.89 +/- 0.75 pg/ml, respectively. These differences were significant compared with the model group (P<0.05). RT-PCR analysis revealed a significant increase in the levels of IFN-gamma and IL-12, and a significant decrease in the mRNA levels of IL-4 and IL-10 (P<0.05). These results indicated that the extracts of Radix Ranunculi Ternati, Radix Sophorae Flavescentis, Prunella Vulgaris L. and Stellera Chamaejasme L. are capable of enhancing cell-mediated immunity in rats by upregulating the levels of genetic transcription. This may explain the observed therapeutic effect of Chinese herbal medicines in the treatment of MDR-TB.