Regulation of T cell lineage commitment by SMAR1 during inflammatory & autoimmune diseases.

Background & objectives: CD4+ T cells are involved in abnormal inflammatory responses causing adverse effects to the body. Th17 cells play a major role in immune disorders and the exact mechanism by which CD4+ T cells regulate its effector Th1 and Th17 phenotype at chromatin level is not clearly understood. This study was aimed to understand the role of matrix associated region (MAR) binding protein SMAR1 (scaffold/matrix attachment region binding protein 1) in T cell differentiation during inflammatory and autoimmune condition using SMAR1 transgenic mice as model. Methods: Wild type (C57BL/6J) and SMAR1 transgenic mice were used for isolation of T cells and further identification of different T cell lineages, along with histological analysis. Further, we studied autoimmune and inflammatory diseases using chemically induced and T cell transfer model of colitis and rheumatoid arthritis to better understand the role of SMAR1 in immune responses. Results: SMAR1 transgenic mice were resistant to dextran sodium sulphate (DSS) induced colitis with decreased expression of Th1 and Th17 specific cytokines. Overexpression of SMAR1 repressed Th17 response by negatively regulating RORγt and IL-17 expression. Downregulation of SMAR1 upregulated signal transducer and activator of transcription 3 (pSTAT3) and IL-17 expression that caused generation of more proinflammatory Th1 and Th17 cells leading to inflammation and disease. Interpretation & conclusions: Our results show an important role of SMAR1 in regulating CD4+ T cell differentiation during inflammatory disorders via regulation of both Th1 and Th17 signaling pathways. This study reveals a critical role of SMAR1 in maintaining the proinflammatory immune responses by repressing Th1 and Th17 cell function and it gives the novel insight into immune regulatory mechanisms.

In vitro callus induction and estimation of plumbagin content from Plumbago auriculata Lam.

The medicinal plant Plumbago contains a very potent secondary metabolite, plumbagin having many therapeutic properties. Callus culture was induced using explants, leaf, stem and shoot apex, from P. auriculata. Murashige and Skoog media fortified with various growth hormones like NAA, IAA, IBA and 2, 4-D individually and in various combinations were checked for callus induction. Among the growth hormones used, 1 mg/L 2, 4-D showed best callusing. The hormonal combinations of 1 mg/L IAA and 1.5 mg/L NAA in the media exhibited best callus induction using stem internode as an explant. Plumbagin content from root, stem, leaf and callus was analyzed by using thin layer chromatographic technique. The callus derived from stem showed comparable plumbagin content to the in vivo plant parts. Quantitative spectrophotometric analysis of plumbagin from plant samples and callus indicated that plumbagin content was maximum in roots which was followed by callus, stem and leaf samples respectively. Generation of in vitro sources for plumbagin, for therapeutic applications will serve as a continuous supply and will contribute to preserve the natural plant recourses.