New Delhi: ‘Kala-azar parasite adopts unique mechanism for spreading disease’

New Delhi: (India Science Wire): Visceral leishmaniasis (commonly known as Kala-azar) is a significant health problem in India caused by the parasite Leishmania donovani. Researchers from the Institute of Microbial Technology (CSIR-IMTech), Chandigarh, have identified a unique mechanism by which the parasite suppresses the host immune response. “An important factor for disease development is suppression of host immunity, which is partly because a specific group of immune cells called ‘dendritic cells’ fail to travel to a host immune activation site known as ‘lymph nodes’ upon infection,” says Dr Pradip Sen, the lead researcher.

Kala-azar is most common in Bihar, Jharkhand, Uttar Pradesh, Kerala, Sikkim and West Bengal. In 1920, Upendranath Brahmachari discovered urea stibamine, which revolutionized the treatment of Kala-azar with over 90% cure rate and minimal side effects. “Currently, there is no effective vaccine against Kala-azar and the treatment is entirely dependent on chemotherapeutics such as sodium antimony gluconate, miltefosine, and amphotericin B,” Dr Sen informs.

The recent emergence of drug-unresponsive cases highlights the need for a new therapeutic strategy to combat the disease. The researchers have found new treatment targets to reduce the parasites’ inhibitory influence on dendritic cell migration, which may improve immunity against the parasite.“Our findings reveal that the parasite inhibits dendritic cell migration to lymph nodes by lowering the expression of a receptor protein (CLEC-2) on dendritic cell surface. It mediates this inhibitory effect through two proteins in dendritic cells. Blocking the activity of either of these two proteins increased the expression of receptor protein on dendritic cells and enhanced subsequent dendritic cell arrival to lymph nodes,” Dr Sen explains.