D2.105 - A Newly Identified Indoor Fungus, Fusarium hechiense, Modulates Allergic Airway Inflammation in a Murine Asthma Model

Indoor fungal exposure is an established risk factor for asthma. Fusarium species are increasingly detected in indoor environments and are reported to exert cytotoxic and immunomodulatory effects, raising concerns about their potential impact on respiratory health; however, the immunological consequences of emerging species such as Fusarium hechiense (F. hechiense) remain poorly characterized. This study investigated the impact of intranasal exposure to F. hechiense, a newly identified indoor fungal species, on allergic airway inflammation in a murine model of asthma.

BALB/c mice were sensitized and challenged with ovalbumin (OVA) to induce allergic airway inflammation. F. hechiense spores (103 CFU; heat-inactivated) were administered intranasally during the challenge phase. Airway hyperresponsiveness (AHR) was measured by methacholine challenge. Bronchoalveolar lavage fluid (BALF) was analyzed for cytokine profiles, serum IgE levels were measured using ELISA, and histopathologic examination of lung tissues were done.

Intranasal exposure to F. hechiense significantly augmented AHR and increased serum IgE levels compared to the OVA control. BALF analysis demonstrated an upregulation of Th1-associated cytokines (IL-2, IL-12, IFN-γ) with concomitant reduction in Th2-associated mediators (IL-4, MDC). Histopathologic analysis revealed increased peri-bronchial inflammation with eosinophilic infiltration, thickening of the airway walls, and pronounced mucus secretion following F. hechiense exposure.

F. hechiense exposure to OVA-sensitized mice intensified hallmark features of allergic airway inflammation, including enhanced AHR and elevated IgE production, while inducing a Th1-skewed immune profile diverging from the conventional Th2-dominant paradigm of allergic asthma. These findings underscore the immunomodulatory potential of under-recognized indoor fungal species and suggest the need for species-specific surveillance of indoor fungal communities in the context of asthma and allergic airway disease.