Murine models of airway fungal exposure and allergic sensitization.

Inhalation of common indoor filamentous fungi has been associated with the induction or exacerbation of allergic respiratory disease. The understanding of fungal inhalation and allergic sensitization has significantly advanced with the use of small animal models, especially mouse models. Numerous studies have employed different animal exposure and sensitization techniques, each with inherent advantages and disadvantages that are addressed in this review. In addition, most studies involve exposure of animals to fungal spores or spore extracts while neglecting the influence of hyphal or subcellular fragment exposures. Recent literature examining the potential for hyphae and fungal fragments to induce or exacerbate allergy is discussed. Innate immune recognition of fungal elements and their contribution to lung allergic inflammation in animal models are also reviewed. Though physical properties of fungi play an important role following exposure, host immune development is also critical in airway inflammation and allergy. We discuss the importance of environmental factors that influence early immune development and subsequent susceptibility to allergy. Murine studies that examine the role of intestinal microflora and prenatal or early life environmental factors that promote allergic sensitization are also evaluated. Future studies will require animal models that accurately reflect natural fungal exposures and identify environmental factors that influence immune development and thus promote respiratory fungal allergy and disease.