Tissue Culture and Drug Discovery

The focus of current research has been in the direction of understanding the mechanisms of pathogenesis in two major tropical infections. In addition, my interest has also been in the interplay between traditional medicine and the modern tools of biotechnology, aimed towards the development of new drugs for the treatment of diabetes and cancer.

Tropical Pulmonary eosinophilia

Circulating filarial proteins elicit strong immunological reactions in humans leading to the chronic manifestations in human lymphatic filariasis such as lymphatic occulusion, fibrosis, oedema and in some cases tropical pulmonary eosinophilia (TPE). The pathogenesis is characterized by immunological hyper responsiveness of the host to the circulating antigens of the degenerating microfilariae in the pulmonary vasculature

We showed using an invitro model that the parasitic sheath proteins induce apoptosis in Hep2 cells which is blocked by the over expression of bcl2. Our studies were the first to demonstrate that the parasitic proteins interact with the epithelial cells leading to cell death. Our focus has been to investigate the molecular switches that control the regulation of cell growth and apoptosis during a pathogenic state. We have investigated various key molecules in this pathogenic cascade in detail. These epithelial cells release cytokines like IL6, IL8 and TNF on exposure to the parasitic sheath proteins, reflecting the immuno modulatory capacity of the epithelium to attract inflammatory cells at the site of infection. We have extended our studies to understand the finer details of the various events that eventually lead to tissue damage in the lungs using this model. This programme is supported by CSIR.

In this context, aqueous two-phase extractive fermentation found to be most effective. Aqueous two-phase has already been established as an excellent tool in the field of biomolecules separation and purification, especially for proteins. We are trying to utilize this wonderful system for purification and extractive fermentation of lipase enzyme from Candida rugosa. Aqueous two-phase systems offer different physical and chemical environments which allow for the partitioning of solutes such as proteins, cells, cell particles and nucleic acids. The differences in the phases are small, and therefore preclude the harsh treatment offered by traditional extraction systems.

Pathogenesis of EPEC diarrhoea

EPEC is a heterogeneous group of organisms, traditionally considered to comprise 12 O serogroups that cause symptoms ranging from acute self-limiting gastroenteritis to persistent life-threatening diarrhoea, especially among the very young. Extensive studies over several years on the interaction of EPEC with cultured cells have led to the generation of a three-stage model of pathogenesis

Several genes have been implicated in formation of AE lesions; these genes map to two sites in the EPEC genome. We have studied the effects of sub-cellular fractions of EPEC on cultured cells. We have demonstrated that outer membrane preparations effect major biochemical and morphological changes in HEp2 cells similar to those observed with whole bacteria, including extrusion of actin positive strands, actin depolymerisation and accumulation at the cell periphery, and marked cytotoxicity.

Our preliminary data suggest that one or more outer membrane proteins (OMPs) of wild type EPEC, in addition to intimin (94 kDa), may play a role in pathogenesis. In particular we have identified a 43-kDa protein; N-terminal sequencing reveals that this has homology with maltoporin (MalB), although it does not require the presence of maltose in the medium for its induction. Such studies are directed towards identifying new molecules that could be used to develop diagnostics. The DST, Government of India has funded the projects in this area of research. A major European Union project in EPEC has been sanctioned to the group.

Bioscreening and isolation of medicinal properties from plant sources towards new drug development: Medicinal plants have been used for the treatment of different diseases in traditional medicines for several generations. The application of modern science and scientific technologies in this area will increase the output for the formulation of the new drugs, which may have the potential value in the treatment of various diseases.

Our goal has been to establish interplay between traditional medicine practiced in South India and modern tools of biotechnology, to determine the specific bioactivities of the medicinal plants using invitro techniques. This will enable us to determine and confirm the specific bioactivity of a particular plant product and validate the same prior to the administration to human subjects either as alternate medicine or allopathic drug. In addition once the bioactivities like anti-cancer, anti-viral, anti-bacterial, anti-diabetic and immune modulatory properties are established for a particular product using these bioscreens, we will then identify the active component structurally which may be used for the development of new drugs. A major initiative in progress is to develop strategies to convert molecule to drug in the country. A Foundation for Advancement of Pharmaceutics has been floated and the major goal is to help in this conversion. The DBT, Government of India has funded several projects in drug discovery.