Abstract
Purpose :
Meibomian gland dysfunction (MGD) is a pervasive condition that is causally related to dry eye, which can result from ocular surface inflammatory diseases, such as chronic ocular allergy, ocular Graft versus Host Disease (oGVHD), and other immune entities. Significantly, the role of inflammatory responses in MGD remains unclear. We previously showed that polymorphonuclear neutrophils (PMN) and T cells (Th17) drive MGD in the chronic-like allergic eye disease (AED) mouse model. Likewise, in humans, PMN abundance in MGD patient tears was inversely correlated with meibum quality (Reyes, N. et al., 2018), suggesting that inflammation is important in patients with MGD. To further evaluate the relationship between immunity and MGD in patients, we performed 36-color spectral flow cytometry on patient tears (“Tear Cytometry”) to define the immune cell landscape and identify associated factors that correlated with MGD severity.
Methods :
Patients with ocular surface immune disease were consented for this study (n=29). Meibography was used to stratify patients into mild, moderate, and severe MGD groups based on meiboscore (Arita, R. et al., 2008). Tears were collected and stained with a 36-marker panel of antibodies (Yu, C. et al., 2021) and analyzed with spectral flow cytometry. Clustering and dimensionality reduction were used to distinguish immune cell populations in an unbiased manner, and population annotations were based on expression of both lineage-defining and supporting markers.
Results :
We identified six major immune cell (CD45) types in patient tears: PMNs (CD16), mononuclear phagocytes (MnP) (CD14), natural killer cells (CD56), B cells (CD19, CD20), CD4 T cells (CD3, CD4), and CD8 T cells (CD3, CD8). MGD severity was correlated with both MnP and PMN abundance in patient tears. Interestingly, tear PMN phenotype changed progressively from mild, to moderate, to severe MGD – this suggests a disease-associated phenotypic shift may occur in human tear PMNs that correlates with MGD severity.
Conclusions :
The notable presence of both PMNs and MnPs in MGD patient tears may provide a novel biomarker for MGD. Further, the presence of MGD-associated phenotypic changes in PMNs is consistent with recent data in the AED mouse model and may provide novel insights into PMN-specific biomarkers of certain forms of MGD.
This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.