T helper subsets in allergic eye disease

Abstract

Purpose of review Ocular allergy is an IgE-mediated disease that results in inflammation of the conjunctiva and, in more severe cases, the cornea. This is driven by an immediate hypersensitivity response via mast cells, followed by a late phase response mediated by eosinophils—both of which are indeed dependent on T helper (Th) lymphocyte activity. Here we provide an update on Th subsets (Th1, Th2, Th17, T regulatory (Treg) and their relevance in ocular allergy. Recent findings Recent evidence in ocular allergy points to an involvement of other Th subsets, in addition to Th2. However, how these subsets are respectively activated and their role in mediating the different clinical forms is poorly understood. Novel mouse models may facilitate addressing such unknowns, and future challenges will involve how to translate such findings into more effective and “patho-specific” treatments. Summary Ocular allergy, especially in severe forms, involves subsets other than Th2. Th1 cells have been detected in mild and severe forms, and recent evidence points to a possible role for IL-17 in severe disease. Tregs, on the other hand, dampen pathogenic Th cell function and allergy immunotherapy is associated with Treg augmentation in disease management. Further understanding of Th biology is warranted and may lead to better therapies.

Mucosal immune tolerance at the ocular surface in health and disease

“…Upon migration to the lymph node, these dendritic cells initiate an effector Th1/Th17 T-cell response that further fuels this vicious cycle at the ocular surface by contributing to epithelial cell damage. and giant papillary conjunctivitis) differ in the contribution of IgE-mediated and non-IgE-mediated immune reactions in their pathogenesis, 93 but they share the hallmark Th2 adaptive immune response to an otherwise harmless antigen that typifies allergic disease. In other words, an allergic reaction at a mucosal surface is in fact a clinical example of the breakdown of mucosal tolerance to one or more specific antigens.…”

Risk of allergic conjunctivitis in patients with type 1 diabetes mellitus: a population-based retrospective cohort study

“…34 However, the role of Th17 in ocular allergy is poorly understood. 27 We hypothesised that the progression of T1DM, which was defined in this study as a yearly increase in aDCSI score, is positively correlated with the risk of AC development. We found a significant trend in increase of AC risk with the progression of T1DM (p for trend <0.001).…”

“…Additional insights into the roles of Tregs and B lymphocytes in both disorders are required. [25][26][27] The control of ocular allergies has been suggested to involve a balance between Tregs and pathogenic T cells, and changes in Treg frequencies have been reported in patients with AC. One study showed that, upon challenge with the Dermatophagoides pteronyssinus allergen, patients with PAC exhibited a higher frequency of CD4+CD25+ cells than healthy controls.…”

Resolvin D1 treatment on goblet cell mucin and immune responses in the chronic allergic eye disease (AED) model

“…Whereas conventional animal models of eye allergy are typically mild and self-limiting in nature 6 , a more recently established system in mice, referred to as the allergic eye disease (AED) model 7,8 , is considered to be akin to chronic/severe forms. Disease in this model is evidenced by a robust eosinophil presence 9 , blepharitis 10 conjunctival scarring 11–13 , thick mucoid discharge, and meibomian gland dysfunction 14 which are consistent with features of chronic disease 15 The AED model is important because the pathobiology of chronic eye allergy is understudied and renewed research efforts are needed to better understand the pathobiology and help reduce disease burden.…”