Design of bispecific CTLA4-IL10 chimera protein as the basis for inflammatory bowel diseases therapy

Inflammation conditions such as inflammatory bowel diseases (IBDs) are multifactorial disorders involve crosstalk between multiple signaling pathways. Often, the precise etiology of the disease remains unclear, and thus current treatments in the clinics are primarily aimed at symptomatic control rather than its molecular origin. Thus, developing selective and effective therapeutics is extremely important. Here, we suggest developing a chimeric protein composed of IL10 and CTLA4 as an immunosuppressive treatment for IBDs. IL10 is an anti-inflammatory and immunosuppressive cytokine identified as being involved in IBDs. IL10 limits immune response-mediated inflammation due to its ability to suppress antigen-presenting cells (APCs) and was tested as anti-inflammatory therapy. However, due to its non-predicted reactivity, it failed. CTLA4, located on T cells, is a negative regulator of T cell activation that binds to CD80/86 receptors expressed on APCs.

Fusion of IL10 to CTLA4 generates a new protein that will simultaneously bind to IL10R and CD80/86 receptors, leading to an immunosuppressive effect on CD80/86+ cells. Further optimization of the proteins could yield higher affinity and specificity to the target cells. Moreover, we examine the stability of CTLA4-IL10 by inserting different linkers which vary in length and type. Preliminary results demonstrate high yield expression and purification of the chimera protein in bacterial and mammalian cells, binding of the chimera CTAL4-IL10 to the cognate receptors CD80 and IL10R, respectively. Our protein thus poses an attractive future therapeutic for immune disorders such as IBD.