Immune Cell Alterations in Eyes Linked to Sjögren’s Severity Bodywide
Alterations to immune dendritic cells in the eyes of people with Sjögren’s syndrome were associated with both bodywide and eye-related disease severity, a study reported.
Using a non-invasive specialized microscope to examine these immune cells on the surface of the eyes might be an objective way of evaluating disease development, classifying patients, and guiding clinical treatment, the researchers noted.
The study, “Alterations in corneal epithelial dendritic cell in Sjogren’s syndrome dry eye and clinical correlations,” was published in the journal Nature Scientific Reports.
In Sjögren’s syndrome, a misguided immune response targets the glands that produce tears (lacrimal) and saliva, leading to dryness in the eyes and mouth.
Dendritic cells are a type of immune cell that plays a central role in activating immune responses. In people with Sjögren’s, these cells have been shown to move into lacrimal and salivary glands, and have also been found in the cornea — the transparent outer layer of the eye.
However, the relationship between dendritic cells in the eyes and characteristics of Sjögren’s has yet to be investigated.
To learn more, researchers in China now recruited 28 individuals with dry eyes due to Sjögren’s syndrome to evaluate specific features of dendritic cells in the cornea. The study also included data from two control groups of 33 people with dry eye disease, caused by other conditions, and a group of 30 healthy volunteers, in its analyses.
Each participant underwent a detailed eye examination that included in vivo (in living people) confocal microscopy (IVCM) imaging. This specialized, non-invasive microscopy imaging technique is used to assess the density and structure of dendritic immune cells.
Based on standard eye assessments, those with Sjögren’s had more severe eye involvement than the healthy controls and the non-Sjögren’s dry eye patients.
IVCM imaging analysis showed that Sjögren’s patients had a significantly higher density of dendritic cells than both control groups. These patients also had more dendritic cell protrusions — called dendrites — per cell, and a larger span of dendritic cells (field) relative to the two control groups. Compared with healthy individuals, non-Sjögren’s dry eye patients had a higher dendritic cell density and more dendrites per cell.
Sjögren’s patients showed a significant correlation between salivary gland involvement, higher dendritic cell density, more dendrites, and a larger dendritic cell field. Significant correlations were also noted between having more dendrites per cell, larger dendritic cells, a more extensive dendritic cell field, and higher levels of several Sjögren’s-associated self-reactive antibodies (autoantibodies).
After adjusting for various influencing factors, a statistical analysis found higher dendritic cell density correlated with a 2.3-times higher risk of salivary gland involvement. Large dendritic cell size was associated with a 1.3-times higher risk of elevated levels of the Sjögren’s-associated antibody anti-SSA.
More dendrites on dendritic cells were linked to an increased risk, of 1.98 times, of salivary gland involvement and a 1.47-times higher risk of being positive for anti-SSA antibodies. The team found no relationships between dendritic cell parameters and other Sjögren’s autoantibodies.
Regarding eye manifestations, higher (worse) ocular surface disease index (OSDI) scores and damage to the eye surface were linked to increased dendritic cell density, more dendrites, and a wider cell field. Higher dendritic cell density was associated with less tear production and poor tear film on the eyes. A larger dendritic cell field also was related to less tear production.
Dry eyes in Sjögren’s syndrome were “characterized by increased [dendritic cell] density, higher [dendritic cell] activation, more dendrites and larger fields,” the researchers wrote. “Such [dendritic cell] alterations could contribute to activity and severity of [Sjögren’s syndrome] and can be detected and quantified by IVCM objectively, allowing its use in evaluating pathogenesis [disease development] and guiding clinical treatment.”