Protective efficacy of piperine against Mycobacterium tuberculosis.

Piperine a trans-trans isomer of 1-piperoyl-piperidine was evaluated for its immunomodulatory activity to enhance the efficacy of rifampicin in a murine model of Mycobacterium tuberculosis infection. In-vitro immunomodulation of piperine was tested on mouse splenocytes for lymphocyte proliferation, cytokine production and macrophage activation. Protective efficacy of piperine was tested in a mice infection model of M. tuberculosis for the activation of Th-1 response and synergistic combination efficacy with rifampicin. Murine splenocytes exposed to piperine exhibited proliferation of T and B cell, increased Th-1 cytokines and enhanced macrophage activation. Piperine (1 mg/kg) in mice infected with M. tuberculosis activated the differentiation of T cells into Th-1 sub-population (CD4+ / CD8+ subsets). There was an increase in secretion of Th-1 cytokines (IFN-γ and IL-2) by these cells. The qRT-PCR studies revealed corresponding increases in the mRNA transcripts of IFN-γ and IL-2 in the infected lung tissues. Combination of piperine and rifampicin (1 mg/kg) exhibited better efficacy of and resulted in additional 1.4 to 0.8 log reduction in lung cfu as compared to rifampicin alone. The up-regulation of Th1 immunity by piperine can be synergistically combined with rifampicin to improve its therapeutic efficacy in immune-compromised TB patients.