Sub-clinical Inflammation In Ocular Mucous Membrane Pemphigoid: 'Hidden' Epithelial CD45INTCD11b+CD16+CD14- Neutrophils May Predict Progression Of Conjunctival Fibrosis

Abstract

Purpose: : Ocular Mucous Membrane Pemphigoid (OcMMP) is a blinding autoimmune disease. Up to 50% of patients demonstrate disease progression in clinically quiescent eyes leading to sight-threatening keratopathy with no biomarkers to aid clinical decision-making. This study was designed to characterise inflammatory cells within the superficial conjunctival epithelium and define whether these could be used to detect ‘sub-clinical’ inflammation and predict progressive fibrosis.

Methods: : 57 patients with OcMMP underwent detailed ocular grading of disease activity and damage (including measurement of conjunctival shrinkage with fornix depth measurements), together with conjunctival ocular surface impression cytology (OSIC) at 0 and 12 months follow-up. Inflammatory cells recovered from OSIC were stained with fluorochrome-conjugated antibodies to identify leukocyte subsets by 9 colour flow cytometry. Comparisons were made with healthy age-matched (n=21) and disease controls (Primary Sjögrens Syndrome; PSS(n=19).

Results: : Conjunctival epithelial CD45^INTCD11b+CD16+CD14- granulocytes were defined as neutrophils and were significantly higher (p<0.0001) amongst patients with OcMMP (109(18%)(n(%)) as compared with PSS(1.8(0.2%)) or healthy volunteers (5.8(0.8%))), and also correlated with disease activity (p<0.001). Importantly, neutrophils were significantly elevated in clinically quiescent eyes compared to healthy controls (44vs.5.8;p=0.02; 7.9vs.0.8%;p<0.001). At 12 months, 53%(37/70) eyes had clinical evidence of progression and patients with measured lower fornix shrinkage were found to have a greater number/percentage of intra-epithelial neutrophils (p<0.001). Moreover, clinically quiescent eyes were more likely to progress when accompanied by a higher proportion of neutrophils (p=0.035) and the degree of conjunctival shrinkage also increased with the number of neutrophils (p=0.04).

Conclusions: : These data indicate an underlying conjunctival neutrophil infiltrate is present in OcMMP, even when the eye appears uninflamed. Quantification of neutrophils by OSIC/flow cytometry could represent a putative biomarker and non-invasive tool for monitoring ongoing disease activity and progression.

Keywords: conjunctiva • flow cytometry • autoimmune disease