Curcumin, the basic ingredient of turmeric, when administered in a nanoparticle formulation has several favourable properties in the treatment of tuberculosis in mice, researchers have found.
Prof. Gobardhan Das from the Special Centre for Molecular Medicine, Jawaharlal Nehru University (JNU) Delhi and his team found nanoparticle curcumin to be five times more bioavailable (which is the proportion of drug that enters circulation after introduction into the body) in mice, than regular curcumin, and was able to drastically reduce liver toxicity induced by TB drug isoniazid.
More importantly, treatment of TB with isoniazid along with 200 nanometre curcumin nanoparticles led to “dramatically reduced” risk of disease reactivation and reinfection. Treatment with anti-tuberculosis drugs takes about six-nine months in the case of drug-sensitive TB and 12-24 months for drug-resistant TB. Besides improper use, the long duration to complete treatment substantially increases the risk of TB bacteria developing resistance.
Host-directed therapy
Because of the increased bioavailability of curcumin, the duration of treatment to achieve complete eradication of the bacteria is reduced significantly. “The treatment time required for complete eradication of bacteria was reduced by 50% in the case of mice,” says Prof. Das.
The results were published in the journal Frontiers in Immunology.
Quite often, patients stop taking anti-TB drugs for a few days due to liver toxicity. Since the addition of curcumin reduces liver toxicity, there can be better treatment adherence and lesser risk of drug resistance emerging.
Like diabetes drug metformin and non-steroidal anti-inflammatory drugs that limit inflammation, curcumin is a host-directed therapy, where the body’s immune system is manipulated, rather than targeting the cause of the disease directly. Besides reducing inflammation, curcumin nanoparticles were found to enhance the immune system.
Curcumin blocks the Kv1.3 potassium channel and prevents apoptosis, or cell death, of T cells that come up with an immune response. As a result, the protective, long-lasting memory cells called the central memory T cells get enhanced.
‘Faster clearance’
“This leads to faster clearance of the TB bacteria, resulting in stronger host immunity against the bacteria and therefore less chances of relapse of the disease after treatment,” said Dr. Dhiraj Kumar Singh from the Special Centre for Molecular Medicine, Jawaharlal Nehru University and one of the lead authors of the study.
Mice, which were treated only with isoniazid, displayed increased susceptibility to re-infection since the drug dampens the immune system. Mice treated with curcumin nanoparticles and isoniazid were able to clear the bacteria at an accelerated rate in both the lungs and spleen.
“Curcumin nanoparticles are stable and can be administered both orally as well as intraperitoneally and, therefore, have greater potential for therapeutic use under different conditions,” they write.