Benzo[a]pyrene (BaP) reportedly has mutagenic and adjuvant activities. We aimed to determine the effects of low-dose BaP administration on allergic airway inflammation and mediastinal lymph node (MLN) cell activation/proliferation in mice. Male C3H/HeJ mice were intratracheally administered ovalbumin (OVA) every 2weeks and/or BaP (0, 0.05, 1 and 20 pmol per animal per week) once per week for 6weeks. The cellular profile of bronchoalveolar lavage (BAL) fluid, histological changes, inflammatory cytokines/chemokines in the lungs, OVA-specific immunoglobulin (Ig) in serum and MLN cell activation/proliferation were examined. BaP administration of 20 pmol with OVA enhanced neutrophil and macrophage accumulation in the lungs. Compared with OVA administration, BaP administration with OVA tended to enhance pulmonary eosinophilia and goblet cell hyperplasia. Furthermore, it increased the levels of interleukin (IL)-5, IL-13, IL-33, monocyte chemoattractant protein-1 and eotaxin in the lungs, and OVA-specific IgG(1) in serum, although not dose-dependently. Compared with the vehicle group, IL-6 and tumor necrosis factor-alpha levels were higher in the OVA+1 pmol BaP group and IL-12 production was higher in the OVA+20 pmol BaP group. Ex vivo studies showed that co-exposure to OVA and BaP activated the MHC class II and CD86 expression in MLN cells. Exposure to BaP with OVA increased IL-4, IL-5 and interferon gamma levels in culture supernatants of OVA-re-stimulated MLN cells. In conclusion, low-dose BaP can, at least in part, enhance allergic airway inflammation by facilitating Th2 responses and activating MLN cells; a high BaP dose may contribute to activating both Th1 and Th2 responses. Copyright (c) 2016 John Wiley & Sons, Ltd.
We examined to determine the effects of low dose BaP intratracheal administration on allergic airway inflammation and mediastinal lymph node (MLN) cell activation/proliferation in male C3H/HeJ mice. This study revealed that real-world exposure levels of BaP can, at least in part, enhance allergic airway inflammation by facilitating Th2 responses and activating MLN cells. In addition, high dose of BaP may contribute in activating both Th1 and Th2 responses.