Bioinformatician University of Colorado St. Louis, Missouri, United States
Abstract Text: Uveitis is a heterogeneous group of ocular inflammatory diseases with a high risk for blindness. As the pathophysiology is poorly understood, current therapies are empiric and fail 30-50% of patients. To better understand patient-specific disease mechanisms, we employed single-cell RNA sequencing. We have shown that T and B lymphocytes are highly enriched and clonally expanded in the ocular fluid from a subset of patients with uveitis, suggesting an immune response triggered by intraocular antigen. Given that the eye is an immunologically sequestered tissue, we hypothesized that a common intraocular antigen might trigger inflammation in this group of patients. To study this, we analyzed the B cell receptor (BCR) sequences in our cohort. We asked whether there were shared V, D, or J segment usage amongst uveitis patients, which would suggest similarity in the specific antigens recognized by these cells. While VH segment frequencies in peripheral blood naïve B cells approximated the frequency of germline VH segments, we found enrichment amongst ocular B cells and plasmablasts of VH1 segments in 75% of patients and VH4 segments in 50% of patients. DH3 segments were also enriched in ocular B cells, whereas JH segment usage was not significantly different between the eye and peripheral blood. Skewed usage of common CDR3 regions by ocular B cells across multiple patients with uveitis suggests that a similar antigen may drive ocular inflammation in these patients. Ongoing studies aim to identify target antigens using monoclonal antibodies derived from patient BCR sequences.
