Glt25d2 Knockout Directly Increases CD25+CD69– but Decreases CD25–CD69+ Subset Proliferation and is Involved in Concanavalin-Induced Hepatitis

Abstract

Background/Aims: The elaborate structure of the extracellular matrix (ECM) and the appropriate surface glycoforms upon it are indispensable to CD4⁺ T cell regulation. Methods: To explore the effects of Glcα1,2Galβ1 glycosylation mediated by GLT25D2 (Colgalt2) for CD4⁺ T cell regulation, we prepared C57BL/6J Glt25d2^-/- mice. In the induction of hepatitis, after concanavalin A (Con A) challenge for 6, 12, and 24 h, more extensive parenchymal injury was noted in Glt25d2^-/- mice than in wild-type (WT) mice at 12 h. Immunohistochemistry and laser scanning confocal microscopy were used to detect GLT25D2 expression, and subsets of CD4⁺T cells was analyzed by flow cytometry. A total of 26 cytokines in serum samples were determined using Luminex technology. Results: The trend in liver injury score variation was consistent with serum alanine aminotransferase and aspartate aminotransferase levels. The levels of interleukin 4 (IL-4), IL-1β, IL-9, and several chemokines such as macrophage inflammatory protein-2, eotaxin, and growth-related oncogene α were significantly increased in Glt25d2^-/- mice compared with WT mice after Con A challenge. A further phenotype analysis of primary Glt25d2^-/- CD4⁺ T cells showed that Glt25d2 knockout increased the frequency of the CD25⁺CD69^- subset but decreased the frequency of the CD25^-CD69⁺ subset after Con A challenge for 6, 12, and 24 h compared with those of WT CD4⁺ T cells. Activation-induced apoptosis was also significantly increased in Glt25d2^-/- CD4⁺ T cells after Con A challenge compared with WT CD4⁺ T cells. Lectin microarray hybridization showed that Glt25d2 knockout increased the binding activity of Narcissus pseudonarcissus lectin to CD4⁺ T cells but Amaranthus caudatus lectin–binding activity was lost during Con A challenge. Conclusion: The present results suggest that collagen glycosylation mediated by GLT25D2 may regulate a subset of CD4⁺ T cells and be involved in the pathogenesis of Con A–induced hepatitis.