Intraepithelial Lymphocytes and LAIR1 Expression in Celiac Disease.

Background

Celiac disease (CD) is a gluten-sensitive immune-related enteropathy of the small intestine characterized by villus atrophy, crypt hyperplasia, and increased intraepithelial lymphocytes (IELs).

Objectives

To characterize the phenotype of IELs and immune cells of the lamina propria of small intestine control using immuno-oncology and immune-phenotype markers and test the most relevant marker, an immune checkpoint co-inhibitory receptor, leukocyte-associated immunoglobulin-like receptor 1 (LAIR1), in CD.

Methods

Immunohistochemical analysis of CD3 (CD3E), CD4, CD8, CD103 (ITGAE), Granzyme B (GZMB), TCR beta (β), TCR delta (δ), CD56 (NCAM), CD16 (FCGR3A), LAIR1 (CD305), PD-L1 (CD274), PD1 (CD279), BTLA (CD272), TOX2, HVEM (TNFRSF14), CD163, HLA-DP-DQ-DR, IL4I1, and FOXP3 was performed using histological analysis. Gene expression analysis was performed using an independent dataset to expand and confirm the findings.

Results

IELs exhibited a cytotoxic T-cell phenotype and were CD3+, CD8+, CD103+, TCR beta+, and LAIR1+. The lamina propria (LP) was abundant in CD163+, HLA-DP-DQ-DR+, BTLA+, PD-L1+, CD103+, CD56+, and LAIR1+ cells corresponding to macrophages and T- and B-lymphocytes. In CD, IELs and part of the inflammatory cells of the lamina propria cells were LAIR1+. CD was characterized by higher quantity of LAIR1+ IELs and LP immune cells than the small intestine control (p = 0.004). Higher intestinal lesions evaluated by Marsh scoring were correlated with higher LAIR1 (p < 0.001). Gene expression analysis confirmed the overexpression of the LAIR1 pathway in CD and highlighted BTLA. At the protein level, BTLA overexpression was confirmed in CD. Finally, as a proof-of-concept AI analysis, a convolutional neural network classified LAIR1-stained image patches between the three diagnoses of small intestine control, CD, and reactive tonsils with high accuracy (99.6%).

Conclusions

IELs exhibit a cytotoxic T-cell phenotype and were found to be CD3+, CD8+, CD103+, TCR beta+, and LAIR1+ in the small intestine control. Increased numbers of LAIR1+ IELs and lamina propria immune cells characterize CD.