Vitamin D enhances resistance to aspergillus fumigatus in mice via inhibition of excessive autophagy.

The role of vitamin D in the regulation of lung immune defense and inflammatory response has attracted more and more attention. Vitamin D deficiency is closely related to respiratory tract infections. However, few studies have elucidated the mechanism of vitamin D deficiency on host pulmonary resistance to Aspergillus fumigatus (A. fumigatus). In this paper, the role of autophagy and Treg regulation in the treatment of rat models of A. fumigatus infection with vitamin D was investigated. We intratracheally injected the A. fumigatus spores into Mice fed with sufficient vitamin D (VitD+) or deficient diets (VitD-). Mortality, fungal load and weight changes were evaluated. The conidia of lung tissue were isolated for analysis of viability. Alveolar macrophages (AMs) were stimulated with a viable A. fumigatus conidia for determining the formation of lysosomes in vitro. The autophagy-related proteins dectin-1, ROS and LC3BII expression in AMs were measured. Fluorescence and Western blot were performed to evaluate the autophagic flux and Treg cells were detected by flow cytometry. After inoculation with A. fumigatus, the vitamin D deficient mice exhibited a higher rate of death, more fungal growth, and more weight loss than its sufficient peers. The viability of A. fumigatus conidia in VitD+ mice was significantly lower than that in VitD- mice. In the case of A. fumigatus infection, vitamin D delays the formation of lysosomes against A. fumigatus through autophagy. The autophagy flow measurement experiment also found that the vitamin D group lowered autophagy levels in cells and a small number of Treg cells. In conclusion, Vitamin D deficiency can lead to impaired lung defense in mice, which may be associated with the formation of excessive autophagy-induced lysosomes and increased counts of Treg cells.