Protection against experimental visceral leishmaniasis by immunostimulation with herbal drugs derived from Withania somnifera and Asparagus racemosus

Abstract

Visceral leishmaniasis (VL) is a vector-borne parasitic disease targeting tissue macrophages. It is among the most neglected infectious diseases. As available therapeutics for treatment of this disease have many side effects, there is a need for safer alternatives. One of the immunopathological consequences of active visceral leishmaniasis is suppression of protective T-helper (Th)-1 cells and induction of disease-promoting Th-2 cells, and thus the treatment of VL relies on immunomodulation. In the current study, herbal drugs derived as whole-plant extracts of Asparagus racemosus and Withania somnifera were used to treat Leishmania donovani-infected BALB/c mice. Keeping the scenario of immunosuppression during VL in mind, the potential of these drugs in the restoration of murine Th-1-type protective immune responses was evaluated. To investigate the propensity of these drugs to treat VL, liver parasite load, delayed-type hypersensitivity responses and parasite-specific immunoglobulin levels were studied. Various biochemical and haematological tests were also carried out. A positive-control group used the standard drug treatment of sodium stibogluconate. Treatment of infected mice with A. racemosus and W. somnifera in combination at the higher dose of 200 mg (kg body weight)−1 not only resulted in a successful reduction in parasite load but also generated protective Th1-type immune responses with normalization of biochemical and haematological parameters, suggesting their potential as potent anti-leishmanial agents.