The role of CISD1 reduction in macrophages in promoting COPD development through M1 polarization and mitochondrial dysfunction

Abstract

Background: The mitochondrial dysfunction and oxidative stress imbalance caused by macrophage polarization play a role in the progression of COPD, with CDGSH iron-sulfur domain-containing protein 1 (CISD1) playing a key role. This study revealed the role and mechanism of CISD1 in smoke-induced macrophages.

Methods: Using a pure cigarette smoke exposure-induced COPD mouse model, stimulation of Raw264.7 macrophages with cigarette smoke extract mimics the COPD environment. Knocking down CISD1 expression in macrophages and combining it with high-throughput sequencing to obtain subsequent differentially expressed genes and pathways. Macrophage polarization tendency under different treatments was determined using flow cytometry. Meanwhile, Mitosox, JC-1, DCFH-DA fluorescence intensity was measured to detect mitochondrial function and cellular oxidative stress levels. Western Blot technique was employed to validate autophagy (mitochondrial autophagy) pathway-related proteins. In addition, Elisa technique was used to measure inflammatory factors (IL-6, TNF-a) in the cell supernatant after co-culturing macrophages (Raw264.7) with epithelial cells (MLE12).

Results: CISD1 is underexpressed in peripheral blood monocytes of COPD patients. Under in vitro conditions, we verified that cigarette smoke (smoke extract) indeed inhibits CISD1 expression in macrophages. Subsequently, we found that macrophages with knocked-down CISD1 tend to polarize towards M1 phenotype, and exhibit signs of mitochondrial dysfunction and oxidative stress imbalance. In addition, we observed significant activation of the autophagy pathway in CISD1-inhibited macrophages, with upregulation of LC3A/B and downregulation of p62 protein, as well as increased expression of mitochondrial autophagy-related proteins (PINK1, PARKN). Furthermore, co-culturing CISD1-knockdown macrophages (Raw264.7) with epithelial cells (MLE12) resulted in upregulation of inflammatory factors in the supernatant.

Conclusions: Smoke-induced reduction of CISD1 in macrophages promotes M1 polarization and mitochondrial dysfunction by activating the autophagy pathway, thereby promoting the occurrence and development of COPD.

Keywords: Autophagy; CDGSH iron–sulfur domain-containing protein 1 (CISD1); Chronic obstructive pulmonary disease (COPD); Microphage; Mitochondrial dysfunction.