Abstract
Background
Excessive activation of M1 macrophages affects the chronic inflammatory response of the airways and leads to the development of chronic obstructive pulmonary disease (COPD). Therefore, it needs to be closely monitored and investigated. MAPK signaling pathway is involved in the activation of M1 macrophages, and N6-methyladenosine (m6A) is involved in the pathogenesis of COPD. However, it is unknown whether activation of the MAPK signaling pathway is mediated by m6A in M1 macrophages in COPD.
Methods
The GEO data were analyzed using bioinformatics techniques to assess the differences between COPD and healthy individuals in the levels of M1 macrophages, their secreted cytokines, and m6A regulators. The MAPK signaling pathway was significantly enriched in the list of differentially regulated genes between COPD and healthy individuals. We further analyzed the correlation between M1 macrophages, m6A, and the MAPK signaling pathway. Next, blood samples from COPD and healthy individuals were collected and analyzed by using flow cytometry, ELISA, and RT-PCR. Western blotting was performed using CSE-induced THP-1 cells. COPD and healthy mice were used for Me-RIP sequencing and flow cytometry experiments. Validation of the results of the above bioinformatics analysis by molecular biology experiments and sequencing techniques.
Results
We found that GEO data and blood specimens from COPD patients showed increased M1 macrophages, higher levels of IL-6 and TNF-α, and higher mRNA expression of key mediators of the MAPK signaling pathway (p38, ERK, and JNK). Western blotting showed increased expression of p38, ERK, and JNK in the CSE group. In contrast, the expression of m6A regulators was low. Also, M1 macrophages in COPD mice were hyperactivated and had reduced m6A modifications of p38, ERK, and JNK compared with control.
Conclusion
m6A may be involved in M1 macrophage hyperactivation by regulating the MAPK signaling pathway, thereby influencing the development of COPD.
Ethical Statement
The studies involving human participants were reviewed and approved by the Ethics Committee of Xinjiang Uygur Autonomous Region Chinese Medicine Hospital. The informed consent obtained from patients included the consent to have their individual details (eg age, gender, ethnicity) published.
Acknowledgments
We acknowledge TopEdit LLC for the linguistic editing and proofreading during the preparation of this manuscript.
Authors´ Contribution
Jing Wang conceived and designed the experiments. Tingting Hu, Min Jiang, Zheng Li, Dan Xu, Jing Jing, Fengsen Li and Jianbing Ding performed the experiments. Tingting Hu analyzed the data. Jing Wang, Tingting Hu, Min Jiang, Dan Xu collected the funds. Tingting Hu and Min Jiang wrote the manuscript. Jing Wang revised the manuscript. All authors made a significant contribution to the work reported, whether that is in the conception, study design, execution, acquisition of data, analysis and interpretation, or in all these areas; took part in drafting, revising or critically reviewing the article; gave final approval of the version to be published; have agreed on the journal to which the article has been submitted; and agree to be accountable for all aspects of the work.
Disclosure
The authors report no conflicts of interest in relation to this work.