Contribution of Th1 and Th17 Cell Responses toward Recoverin Retinal Autoantigen to the Pathogenesis of Autoimmune Retinopathy

Abstract

Purpose : Autoimmune retinopathy (AIR) is a condition that manifests in acute and progressive vision loss in humans. Many AIR patients have responded with stabilization and improvement of vision following treatment with general immune suppressive medications. Laboratory diagnostic tests for AIR have been limited to detection of specific anti-retinal antibodies (ARA) that are thought to drive pathogenesis. Antibodies against the retinal protein recoverin are frequent ARAs detected in AIR patients, which prompted us to study the cellular immune responses against recoverin.

Methods : We have established a murine model to provide a mechanistic approach toward a better understanding of disease processes in AIR. Mice were immunized subcutaneously with recombinant mouse recoverin (100-200 mg) emulsified in complete Freund’s adjuvant. Also, mice were injected intraperitoneally with pertussis toxin (400 ng) on the same day. After three weeks, the immunized mice were scanned with optical coherence tomography (OCT) for detection of pathological changes in the eyes. Spleen and draining lymph nodes were harvested and cells were restimulated with recoverin (5 mg/ml) for 4 days. Supernatants were collected for ELISA cytokine assay. Eyes were harvested and infiltrating lymphocytes were isolated after digestion with collagenase at 37°C for flow cytometry.

Results : Immunization of C57BL/6 and BALB/c mice with mouse recoverin resulted in recoverin-specific T cell responses. Production of IFN-γ and IL-17 were observed in cells harvested from draining lymph nodes and spleen of the immunized mice upon restimulation in vitro with recoverin. Immunization also led to production of high titers of recoverin-specific antibodies (1/400) in the immunized mice. The recoverin-specific Th1 and Th17 cell response was augmented in IL-10 KO mice, whereas humoral response was unaffected. More importantly, the number of lymphocytes infiltrated into the eyes dramatically increased in IL-10 KO mice upon immunization with recoverin. Immunization of Fas ligand deficient GLD mice with recoverin antigen led to a predominant Th17 cell response toward recoverin.

Conclusions : These new insights regarding the anti-recoverin immune response in wild-type and mutant mice have led us to hypothesize that skewing of recoverin-specific T cell response toward inflammatory Th1 and/or Th17 responses can drive the pathogenesis of AIR.

This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.