Dr. Rajni Rani

Immunogenetic bases of differential immune responses in infectious and autoimmune diseases.

Immune responses to the infections differ in different individuals, some people clear the infection, some become immune to further infection and some develop chronic disease. We are interested in studying immunogenetic basis of differential immune responses. Our interests involve an array of genes whose products have a role in the immune response ranging from the Major Histocompatibility Complex (MHC) genes, Low molecular weight proteases (LMP), transporters associated with antigen processing (TAP), Cytotoxic T lymphocyte associated antigen-4 (CTLA-4), cytokine genes, vitamin D receptor genes, PTPN22 to phase II detoxification genes like Glutathione S transferase  and NQO1 genes. The products of these genes interact in integrated networks which results in the final outcome of the infection or autoimmunity in terms of manifestations of, or protection from the diseases. We have been involved in molecular immunogenetic studies of infectious diseases like leprosy and tuberculosis, HCV-HIV co-infections and autoimmune diseases like psoriasis, hypoparathyroidism,  Type 1 Diabetes and vitiligo.

Identification and attenuation of autreactive T cells in Type 1 diabetes along with replenishing  insulin producing stem cells
Type 1 diabetes is an autoimmune disorder where most of the pancreatic beta cells are destroyed before the patients report to the clinic. The only treatment of choice is insulin injections, which does take care of the insulin requirement of the patients but does not really treat the patients. So, we aim to develop a two prong approach where on one hand, we would like to stop autoimmunity by using nano / micro-particle encapsulated peptides. Secondly, we would like to replenish the mice that are lacking the insulin producing beta cells with mesenchymal stem cells (MSCs) that would take care of their natural requirement of insulin. Thus beta cell neogenesis would provide a new therapy along with inhibition of autoimmunity using nano/micro-particle encapsulated peptides. For this purpose, we have encapsulated the peptides (which have earlier shown to inhibit autoimmunity in-vitro) in biodegradable nano/micro particles and are studying their in-vivo efficacy in streptozotocin induced diabetes in Balb/c mice and Non-Obese diabetic (NOD) mice. We are also growing mesenchymal stem cells from bone-marrow of Balb/c mice and studying their efficacy in treatment of diabetes with or without peptide loaded nano-particles. Besides, we are also differentiating MSCs into insulin producing cells using different approaches so that they may be transplanted in diabetic mice to take care of their daily insulin requirement. Successful treatment strategies developed in this way would be helpful in devising ways to treat patients suffering from Type 1 diabetes.

Study of Immunogenetic and autoimmune factors associated with vitiligo

Vitiligo is a depigmenting disorder of the skin caused by selective loss of pigment producing cells called melanocytes. It is the most common pigmentation disorder affecting 0.5-1 % of the world population We are interested in studying the autoimmune and immunogenetic factors associated with predisposition to develop vitiligo and mechanisms of melanocyte destruction and melanin disappearance in vitiligo. We have recently published the largest study on MHC associations in vitiligo. We have studied the molecular signatures of the peptide binding groove of the MHC class-I and II molecules in vitiligo patients and observed significant differences in the key residues involved in peptide binding between the patients and controls suggesting the affinity of auto-antigens being presented by these molecules. We are currently studying the functional implications of the MHC associations in vitiligo.  Besides this, other genes involved in antigen processing and presentation, cytokine genes and phase II detoxification genes are also being investigated to understand the intricate networks in which these genes interact to manifest the complex phenotype of vitiligo.  We observed significant increase in certain cytokines in the lesional skin and peripheral circulation of the patients. We have also studied the expression of genome-wide micro RNAs (miRNA) in the lesional and non-lesional skin and observed certain miRNAs to be significantly increased in the lesional skin of the patients when compared to their own non-lesional skin.  We are now studying the global effect of these cytokines and micro RNAs (that were increased in the lesional skin of vitiligo) on primary melanocyte and keratinocyte cultures to study their role in aetiopathogenesis of vitiligo.