Chronic intermittent hypoxia induces renal fibrosis through MR activation

Obstructive sleep apnea syndrome (OSAS) is a disorder characterized by recurrent arousal from sleep and chronic intermittent hypoxia (CIH). OSAS-associated chronic kidney disease is mainly caused by CIH-induced tissue damage. Therefore, an OSAS model was established by CIH exposure in a hypoxic chamber for five weeks. In our study, macrophage infiltration and macrophage-myofibroblast transition (MMT) were observed in the kidneys of CIH rats and appeared to contribute to the development of renal fibrosis. However, the underlying mechanisms are not well defined. We also found that upon binding to the mineralocorticoid receptor (MR), aldosterone stimulated MMT and consequently led to renal fibrosis under hypoxic conditions. Additionally, an in vitro study of RAW264.7 macrophages demonstrated that MR activation may contribute to MMT, which resulted in a pre -dominant M1 phenotype under hypoxic conditions. These effects were reversed by the MR blocker eplerenone. These results provide preliminary evidence that MR activation might be involved in the transdifferentiation of macrophages into myofibroblasts in the CIH model. The attenuation of renal injury demonstrates a protective role of MR blockade in CIH-induced renal disease.

Automated summary

Obstructive sleep apnea syndrome (OSAS) is a common sleep breathing disorder that is associated with chronic kidney disease. This study found that under hypoxic conditions, macrophages can transform into myofibroblasts, leading to renal fibrosis, and the activation of mineralocorticoid receptor may be involved in this transformation. Blocking mineralocorticoid receptor can attenuate renal injury.