Distinct CRTH2+CD161+ (peTh2) memory CD4+ T-cell cytokine profiles in food allergy and eosinophilic gastrointestinal disorders

Expansion of multiple CD4+ T-cell lineages in lymphocytic variant hypereosinophilic syndrome

BACKGROUND

Lymphocytic variant hypereosinophilic syndrome (LHES) is a rare disorder characterized by hypereosinophilia, the presence of phenotypically aberrant populations of TH2 lymphocytes, and varied clinical manifestations. Although disease pathogenesis has historically been attributed to IL-5-driven hypereosinophilia, response to eosinophil-lowering biologics is not universal, suggesting a more direct role for the aberrant lymphocyte population in disease pathogenesis.

OBJECTIVE

We sought to further delineate the surface phenotypes and cytokine profiles of the aberrant lymphocyte populations in patients with LHES.

METHODS

Multiparameter flow cytometry was used to analyze lymphocytes in whole blood and stored peripheral blood mononuclear cells from a cohort of 42 untreated and treated patients with LHES.

RESULTS

Surface receptor profiling of the aberrant population in 22 untreated patients with LHES, including 8 patients with episodic angioedema with eosinophilia, confirmed prior data demonstrating that the aberrant CD4+ T-cell populations in LHES have a TH2 memory phenotype. CCR8 was identified as a dominant surface marker, unaffected by sample processing or patient treatment status. Serum levels of CCL1, the ligand for CCR8, were increased in LHES patients compared to patients with other hypereosinophilic syndrome subtypes. Expanded populations of FoxP3+Helios+CCR8+ regulatory T cells were identified in many patients with CD3loCD4+ LHES and correlated with the size of the CD3loCD4+ population.

CONCLUSION

These data provide further evidence for direct involvement of the aberrant T-cell populations in disease pathogenesis in LHES and a rationale for further exploration of T-cell-directed therapies.

Differential T follicular helper cell phenotypes distinguish IgE-mediated milk allergy from eosinophilic esophagitis in children

BACKGROUND

IgE-mediated food allergy and eosinophilic esophagitis (EoE) are diseases commonly triggered by milk. Milk-responsive CD4+ T cells producing type 2 cytokines are present in both diseases, yet the clinical manifestation of disease in milk allergy (MA) and EoE are distinct.

OBJECTIVE

We sought to identify differences in CD4+ T cells between EoE and MA that may be responsible for distinct disease manifestations.

METHOD

The total and milk-specific CD4+ T-cell phenotype of children with MA, children with EoE (active or in remission), and controls was measured using spectral flow cytometry of peripheral blood (all groups) or esophageal biopsies (EoE and control).

RESULTS

Circulating milk-responsive T cells could be identified in active EoE and MA. An increased frequency of TH2A cells was also noted in MA and EoE. In circulating T cells, type 2 cytokine production was elevated in MA, but not EoE. Within the milk-responsive T follicular helper (TFH) subset, a dichotomy of phenotype was noted: TFH13 cells predominated in MA, while IL-10-producing TFH cells predominated in EoE. In the esophagus, CD4+ T cells were constitutively activated and expressed not only type 2 cytokines, but also IL-10 and IL-21 in active EoE. IgG4 was produced from CD38+ plasma cells in close proximity to CD4+ T cells. In vitro activation studies demonstrated that IL-10 and IL-21 elicited strong IgG4 responses in B lymphocytes, while IL-4 and IL-13 promoted IgE production.

CONCLUSIONS

Our studies demonstrate a dichotomy of TFH responses that may be the basis for different clinical manifestations to milk in EoE and MA.

Galectin 9 rescues the inducibility of IL-10 expression in regulatory B cells of patients with food allergy

The deregulation of immune responses is what causes food allergy (FA) to occur. FA's cause is still unknown. The goal of this study is to investigate the mechanism how the impaired production of IL-10 occurs in peripheral naive B cells of patients with FA. Samples from patients with FA and healthy controls (HC) were used to isolate CD19+ CD45R+ naive B cells from peripheral blood mononuclear cells (PBMC). Lipopolysaccharide (LPS) exposure was used to assess the expression of interleukin-10 (IL-10) in B cells. Although the FA and HC groups had similar total B cell counts, the FA patients had fewer IL-10+ B cell counts than the HC group. In peripheral B cells, the concentrations of IL-10 were inversely related to the concentrations of specific IgE, Th2 and Th1 cytokines in the serum. In patients with FA, peripheral B cells experienced impaired immune-suppressive functions. Galectin-9 could restore the defective induction of IL-10 expression in naive B cells of FA patients. In conclusion, FA patients with naive B cells experience impaired IL-10 induction. The induction of IL-10 in naive B cells of FA patients can be restored by galectin-9 treatment, which triggers B cells to differentiate into immune regulatory B cells.

Contribution of T cell subsets to different food allergic diseases

Food allergies occur due to a lack of tolerance to the proteins found in foods. While IgE- and non-IgE-mediated food allergies have different clinical manifestations, epidemiology, pathophysiology, and management, they share dysregulated T cell responses. Recent studies have shed light on the contributions of different T cell subsets to the development and persistence of different food allergic diseases. This review discusses the role of T cells in both IgE- and non-IgE-mediated food allergies and considers the potential future investigations in this context.

Triggers for eosinophilic esophagitis (EoE): The intersection of food allergy and EoE

Eosinophilic esophagitis and IgE-mediated food allergy are both food-triggered diseases that are increasing in prevalence. They share many clinical links, including significant comorbidity and similar food triggers, and as atopic diseases, they likely share upstream mechanisms related to barrier function and signals leading to TH2 skewing. In this review, we focus on links between eosinophilic esophagitis and IgE-mediated food allergy with an emphasis on what insights may be derived from overlapping food triggers and immune phenotypes. Through further investigation of these connections, we may be able to better understand not only IgE-mediated food allergy and eosinophilic esophagitis but also general atopic response to food proteins and evolution of allergic response to food.

Pathophysiology of Non-Esophageal Eosinophilic Gastrointestinal Disorders

Eosinophilic gastrointestinal disorder (EGID) is an umbrella term encompassing a group of chronic, immune-mediated disorders characterized by eosinophil-rich inflammation affecting one or more segments of the gastrointestinal tract. A recent consensus in nomenclature and emerging data made possible through multi-center consortia are beginning to unravel the molecular and cellular underpinnings of EGIDs below the esophagus. These emerging findings are revealing both overarching commonalities related to a food allergen-driven, chronic, Th2-mediated immune response as well as location-specific nuances in the pathophysiology of the collective EGIDs. Altogether, these advances offer promise for improved diagnoses and more efficacious interventional strategies.