It has been proposed that infections with helminths can protect from the development of allergic diseases. However, epidemiological and experimental studies have yielded conflicting results. Therefore we investigated if an infection with Nippostrongylus brasiliensis influenced the development of allergen-induced Th2 cell responses in mice. We found a decrease in allergen-induced airway eosinophilia and Eotaxin levels in the airways when mice were infected with the helminths 8 weeks, and especially 4 weeks, but not 1 or 2 weeks before ovalbumin (OVA)-airway challenge. While OVA-specific IgG1 and IgE serum levels and cutaneous hypersensitivity reactions were not reduced by the helminth infection, there was a reduction in OVA-specific IgG1 and IgE levels in bronchoalveolar lavage fluid of mice. Suppression of allergen-induced airway eosinophilia and reduction of Eotaxin production was not observed in IL-10 deficient mice. In addition, we found that helminth-induced airway eosinophilia and Eotaxin production was strongly increased in IL-10 deficient mice infected with the helminths in comparison to control mice. Taken together, these results show that infection with N. brasiliensis suppresses the development of allergen-induced airway eosinophilia and that this effect may be mediated by IL-10. Our results support the view that helminth infections can contribute to the suppression of allergies in humans.

Gastrointestinal stromal tumors (GIST) harboring activating mutations of PDGFRA respond to imatinib, with the notable exception of the most common mutation, D842V. Avapritinib is a novel, potent KIT/PDGFRA inhibitor with substantial clinical activity in patients with the D842V genotype. To date, only a minority of PDGFRA-mutant patients treated with avapritinib have developed secondary resistance. Tumor and plasma biopsies in 6 of 7 patients with PDGFRA primary mutations who progressed on avapritinib or imatinib had secondary resistance mutations within PDGFRA exons 13, 14, and 15 that interfere with avapritinib binding. Secondary PDGFRA mutations causing V658A, N659K, Y676C, and G680R substitutions were found in 2 or more patients each, representing recurrent mechanisms of PDGFRA GIST drug resistance. Notably, most PDGFRA-mutant GISTs refractory to avapritinib remain dependent on the PDGFRA oncogenic signal. Inhibitors that target PDGFRA protein stability or inhibition of PDGFRA-dependent signaling pathways may overcome avapritinib resistance. Significance: Here, we provide the first description of avapritinib resistance mechanisms in PDGFRA-mutant GIST. This article is highlighted in the In This Issue feature, p. 1

Taken together our data suggest that live BCG>hk-BCG>CpG-ODN >PPD are effective in suppressing allergen-induced Th2 responses. The degree of suppression and the component of the Th2 response affected (airway inflammation vs. the production of allergen-specific IgE and IgG1) were dependent upon the adjuvant used and how it was applied. Our results contribute to the design of novel vaccines protecting humans from developing allergic disorders.

Background: Knowledge of the factors which control IgE production is essential in order to understand the pathogenesis of immediate hypersensitivity reactions. We have studied the extent to which the route and frequency of antigen application as well as different antigen amounts may influence IgE synthesis. Methods: We established sensitisation protocols in BALB/c mice, in which various doses of ovalbumin (Ova) were applied via intranasal, epicutaneous or intraperitoneal routes. Ova-specific antibodies were measured by ELISA. After 6 weeks of sensitisation, anaphylactic shock was measured following intravenous challenge with Ova. In addition, bronchoalveolar lavages were performed in intranasally sensitised mice. Results: We were able to show that the most efficient IgE production was achieved by long-term antigen application via the airways, leading to local allergic airway pathology. The epicutaneous route of antigen application also induced very high IgE titres, while intraperitoneal sensitisation led to significantly lower IgE levels. After intraperitoneal sensitisation, IgE synthesis was best induced by increasing the frequency of antigen application, but not by increasing the amount of antigen. In all groups of mice, Ova-specific IgE antibodies were high enough to induce systemic allergic symptoms leading to anaphylactic shock. The severity of shock correlated with the amount of specific IgE. Conclusions: Taken together, our results demonstrate that antigen application via the airways or skin induces IgE synthesis more efficiently than via the intraperitoneal route. Few exposures with high-dose antigen are less efficient than multiple exposures with low doses. Our finding that both the route and the frequency of antigen application strongly influence IgE synthesis may help to understand how environmental antigens lead to allergic sensitisation.