Pathogen induced regulatory cell populations preventing allergy through the Th1/Th2 paradigm point of view

Immunomodulatory effects of EGCG fraction of green tea extract in innate and adaptive immunity via T regulatory cells in murine model

Green tea is a widely consumed beverage known for its beneficial anti-inflammatory, anti-oxidative, anti-mutagenic, anti-carcinogenic, and cardioprotective properties. Here, we administered epigallocatechin gallate fraction of green tea extract (EGTE) to mice for 6 weeks and examined the effects on the innate and adaptive immune responses by measuring phagocytic and natural killer (NK) cell activity, as well as antigen-specific proliferation, cytolysis, cytokine secretion, and antibody production. Our data show that EGTE administration increased NK cell cytolysis and peritoneal cell phagocytosis, as well as splenocyte proliferation and secretion of IL-2 and IFN-γ. Of note, EGTE treatment decreased the production antigen-specific IgE via increased the proportion of CD4+ CD25+ regulatory T lymphocytes in the spleen, suggesting that EGTE may play a role in regulating the allergic response.

Effect of parasite infection on allergic disease

Vertebrates and helminths have co-evolved for 500 million years, developing mutual adaptation mechanisms between parasites and hosts. Today, however, helminth diseases are among the most neglected communicable diseases. Epidemiological evidence shows that exposure to helminth parasites is inversely correlated with allergy incidence, and helminths induce immune hyporeactivity in both the innate and adaptive systems. The mechanisms include parasite-derived regulatory molecules, the study of which opens new avenues for the control of allergic and autoimmune diseases.

Selective depletion of Foxp3+ Treg during sensitization phase aggravates experimental allergic airway inflammation

Recent studies highlight the role of Treg in preventing unnecessary responses to allergens and maintaining functional immune tolerance in the lung. We investigated the role of Treg during the sensitization phase in a murine model of experimental allergic airway inflammation by selectively depleting the Treg population in vivo. DEpletion of REGulatory T cells (DEREG) mice were depleted of Treg by diphtheria toxin injection. Allergic airway inflammation was induced using OVA as a model allergen. Pathology was assessed by scoring for differential cellular infiltration in bronchoalveolar lavage, IgE and IgG1 levels in serum, cytokine secretion analysis of lymphocytes from lung draining lymph nodes and lung histology. Use of DEREG mice allowed us for the first time to track and specifically deplete both CD25(+) and CD25(-) Foxp3(+) Treg, and to analyze their significance in limiting pathology in allergic airway inflammation. We observed that depletion of Treg during the priming phase of an active immune response led to a dramatic exacerbation of allergic airway inflammation in mice, suggesting an essential role played by Treg in regulating immune responses against allergens as early as the sensitization phase via maintenance of functional tolerance.