Activation of Vitamin D Regulates Response of Human Bronchial Epithelial Cells to Aspergillus fumigatus in an Autocrine Fashion

Figure 2

Locally activated vitamin D synergistically increases the expression of LL-37 and HBD2 in 16HBE cells infected with A. fumigatus but attenuates A. fumigatus-induced production of chemokines and cytokines. (a)–(c) 16HBE cells were untreated (basal) or stimulated with resting conidia (RC) or swollen conidia (SC) (MOI = 1-2) for 24 h in the presence of either inactive (25D₃; 10⁻⁷ M) or active vitamin D (1,25D₃; 10⁻⁷ M). Locally activated vitamin D synergistically induces protein expression of LL-37 and β-defensin-2 (HBD2) to a similar extent as exogenous active vitamin D (a). The protein expression of LL-37 and β-defensin-2 (HBD2) was evaluated by Western blot analysis. The Western blots illustrated are from one representative experiment out of three and converted to densitometry units in respective graphs. (b)-(c) Locally activated vitamin D attenuates A. fumigatus-induced production of chemokines and cytokines in 16HBE cells to a similar extent as exogenous active vitamin D. TNF-α, IL-1β, IL-6, and IL-8 mRNA expression was measured using quantitative real-time PCR (b). The concentrations of TNF-α and IL-8 in culture supernatants of 16HBE cells were measured by ELISA (c). Values reflect mean fold change from control and SEM of three independent experiments. Student’s -test, ^∗, ^∗∗, and ^∗∗∗, for comparison with baseline; ^# and ^##, for comparison with control.

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