Immunoglobulin G4 in eosinophilic esophagitis: Immune complex formation and correlation with disease activity.

BACKGROUND: Recent studies have shown deposition of immunoglobulin G4 (IgG4) and food proteins in the esophageal mucosa of eosinophilic esophagitis (EoE) patients. Our aims were to assess whether co-localization of IgG4 and major cow's milk proteins (CMPs) was associated with EoE disease activity and to investigate the proteins enriched in proximity to IgG4 deposits. METHODS: This study included adult subjects with EoE (n = 13) and non-EoE controls (n = 5). Esophageal biopsies were immunofluorescence stained for IgG4 and CMPs. Co-localization in paired samples from active disease and remission was assessed and compared to controls. The proteome surrounding IgG4 deposits was evaluated by the novel technique, AutoSTOMP. IgG4-food protein interactions were confirmed with co-immunoprecipitation and mass spectrometry. RESULTS: IgG4-CMP co-localization was higher in the active EoE group compared to paired remission samples (Bos d 4, p = .02; Bos d 5, p = .002; Bos d 8, p = .002). Co-localization was also significantly higher in the active EoE group compared to non-EoE controls (Bos d 4, p = .0013; Bos d 5, p = .0007; Bos d 8, p = .0013). AutoSTOMP identified eosinophil-derived proteins (PRG 2 and 3, EPX, RNASE3) and calpain-14 in IgG4-enriched areas. Co-immunoprecipitation and mass spectrometry confirmed IgG4 binding to multiple food allergens. CONCLUSION: These findings further contribute to the understanding of the interaction of IgG4 with food antigens as it relates to EoE disease activity. These data strongly suggest the immune complex formation of IgG4 and major cow's milk proteins. These immune complexes may have a potential role in the pathophysiology of EoE by contributing to eosinophil activation and disease progression.

2. Cytokines and chemokines.

Cytokines and chemokines are redundant secreted proteins with growth, differentiation, and activation functions that regulate and determine the nature of immune responses and control immune cell trafficking and the cellular arrangement of immune organs. Which cytokines are produced in response to an immune insult determines initially whether an immune response develops and subsequently whether that response is cytotoxic, humoral, cell-mediated, or allergic. A cascade of responses can be seen in response to cytokines, and often several cytokines are required to synergize to express optimal function. An additional confounding variable in dissecting cytokine function is that each cytokine may have a completely different function, depending on the cellular source, target, and, most important, specific phase of the immune response during which it is presented. Numerous cytokines have both proinflammatory and anti-inflammatory potential; which activity is observed depends on the immune cells present and their state of responsiveness to the cytokine. For this chapter, cytokines are grouped according to those that are mononuclear phagocytic-derived or T-lymphocytic-derived; that mediate cytotoxic (antiviral and anticancer), humoral, cell-mediated, or allergic immunity; and that are immunosuppressive. The biology of chemokines are then reviewed, grouped by family.

Evaluation of cytokines in nasal secretions after nasal antigen challenge: lack of influence of antihistamines.

BACKGROUND: Previous studies of inflammation in allergic rhinitis using nasal irrication have been unsatisfactory because of 1) poor reproducibility; 2) the tendency of irrigation to overdilute mediators; and 3) the failure of this technique to evaluate interstitial concentrations of relevant mediators. For this study we used filter paper as a matrix to collect nasal secretions in patients undergoing nasal antigen challenge. OBJECTIVE: To evaluate inflammatory mediators of allergen-induced rhinitis during a clinical trial of fexofenadine. METHODS: Subjects evaluated at a referral medical center were placed on traditional dosing of fexofenadine at 60 mg, twice daily, or placebo in a double-blind, crossover fashion for 1 week before the nasal challenge. Nasal challenge was performed with nasal insufflation of either 1,000 AU timothy or 0.1 mL ragweed (1:100 wt/vol) extract outside the pollen season. Nasal secretions were collected at baseline and then at 2, 4, and 6 hours after nasal challenge. Secretions were evaluated for expression of the cellular adhesion molecule-1, tumor necrosis factor (TNF)-alpha, interleukin (IL)-4, IL-10, macrophage inflammatory protein (MIP)-1alpha, and granulocyte-macrophage colony-stimulating factor (GM-CSF) using commercially available enzyme-linked immunoadsorbent assay kits. Patients' symptom scores were evaluated during the nasal challenge. RESULTS: Significantly (P < 0.05) increased peak levels of TNF-alpha, IL-4, IL-10, and MIP-1alpha were detected after antigen challenge as compared with baseline levels. There was a nonsignificant trend toward an increase in GM-CSF after antigen challenge (P = 0.07). There was no difference in the peak levels of TNF-alpha, IL-4, IL-10, MIP-1alpha, or GM-CSF measured when patients were on fexofenadine versus placebo. Finally, there were no significant differences in patients' symptom scores during antigen challenge when subjects were on fexofenadine versus placebo. CONCLUSIONS: Collection of nasal secretions using a filter paper matrix provides a reproducible model for accurately detecting and evaluating changes in cytokine levels after nasal challenge. Cytokine levels tend to peak 3 to 4 hours after antigen challenge. Standard doses of fexofenadine do not seem to have a mitigating effect on the production of these cytokines. Symptoms of allergic rhinitis using this type of antigen challenge did not differ from treatment with fexofenadine versus placebo.