Aqueous macrophages contribute to conserved CCL2 and CXCL10 gradients in uveitis

Purpose: Uveitis is a heterogenous group of inflammatory eye disease for which current cytokine-targeted immune therapies are effective for only a subset of patients. We hypothesized that despite pathophysiologic nuances that differentiate individual disease states, all forms of eye inflammation might share common mechanisms for immune cell recruitment. Identifying these mechanisms is critical for developing novel, broadly acting therapeutic strategies. Design: Experimental study. Subjects: Biospecimens from patients with active or inactive uveitis and healthy controls. Methods: Protein concentration and single cell gene expression were assessed in aqueous fluid biopsies and plasma samples from deidentified patients with uveitis or healthy controls. Main Outcome Measures: The concentration of 31 inflammatory proteins was measured in all aqueous samples, as well as plasma samples from patients with active uveitis. Chemokine and cytokine ligand and receptor expression were assessed in individual cell types from aqueous biopsies obtained from patients with active uveitis. Results: We identified 6 chemokines that were both elevated in active uveitis compared with controls and enriched in aqueous compared with plasma during active uveitis (C-C motif chemokine ligand [CCL]2, C-X-C motif chemokine ligand [CXCL]10, CXCL9, CXCL8, CCL3, and CCL14), forming potential gradients for migration of immune cells from the blood to the eye. Of these, CCL2 and CXCL10 were consistently enriched in the aqueous of all patients in our cohort, as well as in a larger cohort of patients from a previously published study. These data suggest that CCL2 and CXCL10 are key mediators in immune cell migration to the eye during uveitis. Next, single cell RNA sequencing suggested that macrophages contribute to aqueous enrichment of CCL2 and CXCL10 during human uveitis. Finally, using chemokine ligand and receptor expression mapping, we identified a broad signaling network for macrophage-derived CCL2 and CXCL10 in human uveitis. Conclusions: These data suggest that ocular macrophages may play a central role, via CCL2 and CXCL10 production, in recruiting inflammatory cells to the eye in patients with uveitis. Financial Disclosure(s): Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article.