Soluble Collectin 11 (CL-11) Acts as an Immunosuppressive Molecule Potentially Used by Stem Cell-Derived Retinal Epithelial Cells to Modulate T Cell Response

Abstract

Retinal pigment epithelium (RPE) cell allotransplantation is seen as a possible solution to retinal diseases. However, the RPE-complement system triggered by the binding of collectin-11 (CL-11) is a potential barrier for RPE transplantation as the complement-mediated inflammatory response may promote T cell recognition. To address this, we investigated the role of CL-11 on T cell immuno-response. We confirmed that RPE cells up-regulated MHC class I and expressed MHC class II molecules in an inflammatory setting. Co-cultures of RPE cells with T cells led to the inhibition of T cell proliferation. We found that CL-11 was partially responsible for this effect as T cell binding of CL-11 inhibited T cell proliferation in association with the downregulation of CD28. We also found that the suppressive action of CL-11 was abrogated in the presence of the RGD peptide given to block the T cell binding of CL-11 by its collagen-like domain. Because RPE cells can bind and secrete CL-11 under stress conditions, we postulate that soluble CL-11 contributes to the immunosuppressive properties of RPE cells. The investigation of this dual biological activity of CL-11, namely as a trigger of the complement cascade and a modulator of T cell responses, may provide additional clues about the mechanisms that orchestrate the immunogenic properties of RPE cells.

Collectin-K1 Plays a Role in the Clearance of Streptococcus agalactiae in Nile Tilapia (Oreochromis niloticus)

“…Additionally, CL-K1 takes part in the innate immunity as a mediator, exhibiting antibacterial and modulatory roles in uropathogenic Escherichia coli (UPEC) infection [ 23 ]. It acts as an initiator of the complement cascade and a regulator of T-cell reactions, providing insights into the underlying mechanisms that regulate the immunogenic characteristics of retinal pigment epithelium cells [ 24 ]. Mutations in the CL-K1 or MASP-1/3 genes may affect normal body development, resulting in a 3MC syndrome which encompasses the overlapping Carnevale, Mingarelli, Malpuech, and Michels syndromes [ 21 , 25 ].…”