Overexpression of human interleukin 6 in NaCl inducible bacterial system and its characterization

Human Interleukin-6 (hIL6) is a multifunctional cytokine that plays a central role in host defence system due to its wide range of immune and hematopoietic activities. hIL-6 stimulates the inflammatory and autoimmune processes in many diseases such as multiple sclerosis, diabetes, atherosclerosis, Alzheimer's disease, systemic lupus erythematous, multiple myeloma, prostate cancer & rheumatoid arthritis. Due to its clinical and research relevance, production of recombinant hIL-6 in biologically active state is considerably important. In this study, we reported successful cloning, transformation, expression, purification and characterization of hIL-6 by using salt inducible expression system i.e. GJ1158. The hIL6 was subcloned from pcDNA3.1 into the prokaryotic expression vector pRSET-B and transformed in GJ1158. Recombinant expression of protein was done by NaCl at mid-log phase. Cobalt-NTA affinity chromatography (IMAC) and S-200 size exclusion chromatography (SEC) were used to obtain approx. 95% purified hIL6 protein (1.5 mg; 18.8% overall recovery). The recombinant hIL-6 was confirmed by western blotting and MALDI-TOF MSMS while functional validation was done by ELISA and MTT assay. The study establishes a cost effective and environmentally favourable strategy for producing recombinant hIL-6 in a prokaryotic host without compromising structural and functional properties. This expression system can used to produce hIL-6 for research, diagnostic and potential therapeutic applications.