Abstract
Purpose :
Suppressor of Cytokines Signaling 1 (SOCS1) is a cytoplasmic protein that limits the extent and duration of inflammatory response. We have shown that a cell penetrating peptide from the kinase inhibitory region (KIR) from SOCS1 (denoted as R9-SOCS1-KIR) can dampen the signaling emanating from JAK/STAT and TLR2/4 pathways. We have examined the ability of this peptide to counteract the inflammation caused by lipopolysaccharide (LPS), which is released during an infection or from leaching of intestinal microbiota.
Methods :
R9-SOCS-KIR or its inactive control peptide were tested for anti-inflammatory properties in a mouse macrophage cell line, J774A.1, used as a surrogate for microglia and treated with LPS. Induction of inflammatory markers was tested by ELISA using the supernatants from treated cells, or Western blot analysis of treated cell extracts. Activation of inflammatory transcription factors was analyzed by following their nuclear translocation. ARPE-19 cells that were differentiated by growing for 4 weeks and treated with LPS with or without R9-SOCS1-KIR were used to evaluate the integrity of tight junction protein by immunostaining and by measurement of transepithelial electrical resistance (TEER).
Results :
Treatment of J774A.1 cells with LPS resulted in secretion of NO and IL-1b, which was attenuated by R9-SOCS1-KIR. Induction of inflammatory markers, cyclooxygenase 2 (COX2) and iNOS observed in cells treated with LPS was suppressed when R9-SOCS1-KIR was simultaneously present. Treatment with LPS resulted in nuclear translocation of p65, the active subunit of NF-kB and the MAP kinase p38, both of which were prevented in the presence of R9-SOCS1-KIR. Uniform distribution of Zona occludens 1 (ZO-1) along the cell membrane was disrupted and TEER reduced by treatment with LPS, both of which were prevented by R9-SOCS1-KIR.
Conclusions :
Protection against inflammatory insults afforded by R9-SOCS1-KIR in a macrophage cell line and a cell line from retinal pigment epithelium suggests that it has therapeutic potential against inflammatory ocular disorders, including infection induced uveitis.
This is a 2021 ARVO Annual Meeting abstract.