rIL‐10 enhances IL‐10 signalling proteins in foetal alveolar type II cells exposed to hyperoxia

Although the mechanisms by which hyperoxia promotes bronchopulmonary dysplasia are not fully defined, the inability to maintain optimal interleukin (IL)‐10 levels in response to injury secondary to hyperoxia seems to play an important role. We previously defined that hyperoxia decreased IL‐10 production and pre‐treatment with recombinant IL‐10 (rIL‐10) protected these cells from injury. The objectives of these studies were to investigate the responses of IL‐10 receptors (IL‐10Rs) and IL‐10 signalling proteins (IL‐10SPs) in hyperoxic foetal alveolar type II cells (FATIICs) with and without rIL‐10. FATIICs were isolated on embryonic day 19 and exposed to 65%‐oxygen for 24 hrs. Cells in room air were used as controls. IL‐10Rs protein and mRNA were analysed by ELISA and qRT‐PCR, respectively. IL‐10SPs were assessed by Western blot using phospho‐specific antibodies. IL‐10Rs protein and mRNA increased significantly in FATIICs during hyperoxia, but JAK1 and TYK2 phosphorylation showed the opposite pattern. To evaluate the impact of IL‐8 (shown previously to be increased) and the role of IL‐10Rs, IL‐10SPs were reanalysed in IL‐8‐added normoxic cells and in the IL‐10Rs’ siRNA‐treated hyperoxic cells. The IL‐10Rs’ siRNA‐treated hyperoxic cells and IL‐8‐added normoxic cells showed the same pattern in IL10SPs with the hyproxic cells. And pre‐treatment with rIL‐10 prior to hyperoxia exposure increased phosphorylated IL‐10SPs, compared to the rIL‐10‐untreated hyperoxic cells. These studies suggest that JAK1 and TYK2 were significantly suppressed during hyperoxia, where IL‐8 may play a role, and rIL‐10 may have an effect on reverting the suppressed JAK1 and TYK2 in FATIICs exposed to hyperoxia.