Interaction with Epithelial Cells Modifies Airway Macrophage Response to Ozone

Abstract

The initial innate immune response to ozone (O 3 ) in the lung is orchestrated by structural cells, such as epithelial cells, and resident immune cells, such as airway macrophages (Macs). We developed an epithelial cell-Mac coculture model to investigate how epithelial cell-derived signals affect Mac response to O 3 . Macs from the bronchoalveolar lavage (BAL) of healthy volunteers were cocultured with the human bronchial epithelial (16HBE) or alveolar (A549) epithelial cell lines. Cocultures, Mac monocultures, and epithelial cell monocultures were exposed to O 3 or air, and Mac immunophenotype, phagocytosis, and cytotoxicity were assessed. Quantities of hyaluronic acid (HA) and IL-8 were compared across cultures and in BAL fluid from healthy volunteers exposed to O 3 or air for in vivo confirmation. We show that Macs in coculture had increased markers of alternative activation, enhanced cytotoxicity, and reduced phagocytosis compared with Macs in monoculture that differed based on coculture with A549 or 16HBE. Production of HA by epithelial cell monocultures was not affected by O 3 , but quantities of HA in the in vitro coculture and BAL fluid from volunteers exposed in vivo were increased with O 3 exposure, indicating that O 3 exposure impairs Mac regulation of HA. Together, we show epithelial cell-Mac coculture models that have many similarities to the in vivo responses to O 3 , and demonstrate that epithelial cell-derived signals are important determinants of Mac immunophenotype and response to O 3 .

Ozone-derived Oxysterols Affect Liver X Receptor (LXR) Signaling

“…Effects of O 3 on Cholesterol Efflux and Cytokine Gene Expression-As expected and previously described by us (30,31), exposure to O 3 caused an inflammatory response as marked by increased gene expression (Fig. 4, A and B) and protein concentration (Fig.…”

Differential expression of pro-inflammatory and oxidative stress mediators induced by nitrogen dioxide and ozone in primary human bronchial epithelial cells

“…The cells were then exposed to 4 different concentrations of nitrogen dioxide (1 ppm, 2 ppm, 3 ppm, or 5 ppm) or ozone (0.25 ppm, 0.50 ppm, 0.75 ppm, or 1.00 ppm) for 2 hours in exposure chambers held at 37.5 °C, 5% CO 2 , and 88% relative humidity (Devlin et al, 1994, McKinnon et al, 1993, Bauer et al, 2015). Simultaneous to each NO 2 and O 3 exposure, additional cells were exposed to filtered air at the same temperature, humidity, and air flow rate that was used for the pollutant exposures; this served as our negative control.…”

Pulmonary macrophages: key players in the innate defence of the airways

“…Macrophages may also be activated by ambient particulate matter containing TLR activating microbial products such as lipopolysaccharide, β-glucan, bacteria and fungal spores 86 87. Bauer et al 88 showed that co-culture of human primary AMs with epithelial cells modifies macrophage responses to O 3 , enhancing M2 activation status and reducing phagocytic activity. Goto et al 89 demonstrated that cytokine production by AM in response to particulate air pollution accelerates monocyte release from the bone marrow.…”