Fine particulate matter with an aerodynamic diameter less than 2.5 μm (PM2.5) is a serious air pollutant associated with health problems. Macrophages play an important role in the process of PM2.5-induced inflammation in respiratory diseases. However, the detailed mechanism remains unclear. We aimed to examine the mechanism of PM2.5-induced inflammation and find possible anti-inflammatory inhibitors. PM2.5 was collected in Hangzhou, China, and the composition of adsorbed materials on PM2.5 was characterized. RAW 254.7 cells were then treated with PM2.5. Phagocytosis was observed, and inflammatory response was triggered as demonstrated by the release of high levels of monocyte chemoattractant protein-1(MCP-1), tumor necrosis factor-α (TNF-α), and interleukin-6 (IL-6) and increased mRNA expression of inducible nitric oxide synthase (iNOS) and TNF-α. Treatment with classic inhibitors suppressed the released pro-inflammatory factors in a dose-dependent manner. Using Immunology Inflammation Compound Library, we screened 70 inhibitors and clustered them based on similarities in their inhibitory effects, which we detected using cytometric bead array (CBA) assay. Molecular analysis revealed that the expression of toll-like receptor 4 (TLR4), nuclear factor kappa-B (NF-κB), and cyclooxygenase-2 (COX-2) was increased in PM2.5-stimulated RAW 254.7 cells. Corresponding inhibitors were selected, and the CBA assay verified their anti-inflammatory effects. These inhibitors reduced the expression of pro-inflammatory factors, and this reduction was correlated with the downregulation of the TLR4/NF-κB/COX-2 signaling pathway. In conclusion, PM2.5 induces an inflammatory response in macrophages via activation of TLR4/NF-κB/COX-2 signaling, and the inhibitors of this pathway are potential therapeutic candidates to treat inflammatory disorders.
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An, Z., R.J. Huang, R. Zhang, X. Tie, G. Li, J. Cao, W. Zhou, Z. Shi, Y. Han, Z. Gu, and Y. Ji. 2019. Severe haze in northern China: a synergy of anthropogenic emissions and atmospheric processes. Proceedings of the National Academy of Sciences of the United States of America 116 (18): 8657–8666.
Asea, A., M. Rehli, E. Kabingu, J.A. Boch, O. Bare, P.E. Auron, M.A. Stevenson, and S.K. Calderwood. 2002. Novel signal transduction pathway utilized by extracellular HSP70: role of toll-like receptor (TLR) 2 and TLR4. The Journal of Biological Chemistry 277 (17): 15028–15034.
Atkinson, R.W., S. Kang, H.R. Anderson, I.C. Mills, and H.A. Walton. 2014. Epidemiological time series studies of PM2.5 and daily mortality and hospital admissions: a systematic review and meta-analysis. Thorax 69 (7): 660–665.
Bekki, K., T. Ito, Y. Yoshida, C. He, K. Arashidani, M. He, G. Sun, Y. Zeng, H. Sone, N. Kunugita, and T. Ichinose. 2016. PM2.5 collected in China causes inflammatory and oxidative stress responses in macrophages through the multiple pathways. Environmental Toxicology and Pharmacology 45: 362–369.
Cai, X., Z. Li, E.M. Scott, X. Li, and M. Tang. 2016. Short-term effects of atmospheric particulate matter on myocardial infarction: a cumulative meta-analysis. Environmental Science and Pollution Research International 23 (7): 6139–6148.
Chatterjee, B., B. Banoth, T. Mukherjee, N. Taye, B. Vijayaragavan, S. Chattopadhyay, J. Gomes, and S. Basak. 2016. Late-phase synthesis of IκBα insulates the TLR4-activated canonical NF-κB pathway from noncanonical NF-κB signaling in macrophages. Science Signaling 9 (457): ra120.
Cho, Y.S., and H.B. Moon. 2010. The role of oxidative stress in the pathogenesis of asthma. Allergy, Asthma & Immunology Research 2 (3): 183–187.
Choi, K.M., P.C. Kashyap, N. Dutta, G.J. Stoltz, T. Ordog, T. Shea Donohue, A.J. Bauer, D.R. Linden, J.H. Szurszewski, S.J. Gibbons, and G. Farrugia. 2010. CD206-positive M2 macrophages that express heme oxygenase-1 protect against diabetic gastroparesis in mice. Gastroenterology 138 (7): 2399–2409.
Feng, S., D. Gao, F. Liao, F. Zhou, and X. Wang. 2016. The health effects of ambient PM2.5 and potential mechanisms. Ecotoxicology and Environmental Safety 128: 67–74.
Ghio, A.J., M.S. Carraway, and M.C. Madden. 2012. Composition of air pollution particles and oxidative stress in cells, tissues, and living systems. Journal of toxicology and environmental health. Part B, Critical reviews 15 (1): 1–21.
Ghosh, S., M.J. May, and E.B. Kopp. 1998. NF-kappa B and Rel proteins: evolutionarily conserved mediators of immune responses. Annual Review of Immunology 16: 225–260.
Hamidzadeh, K., S.M. Christensen, E. Dalby, P. Chandrasekaran, and D.M. Mosser. 2017. Macrophages and the recovery from acute and chronic inflammation. Annual Review of Physiology 79: 567–592.
He, M., T. Ichinose, S. Yoshida, T. Ito, C. He, Y. Yoshida, K. Arashidani, H. Takano, G. Sun, and T. Shibamoto. 2017. PM2.5-induced lung inflammation in mice: differences of inflammatory response in macrophages and type II alveolar cells. Journal of Applied Toxicology 37 (10): 1203–1218.
Hiraiwa, K., and S.F. van Eeden. 2013. Contribution of lung macrophages to the inflammatory responses induced by exposure to air pollutants. Mediators of Inflammation 2013: 619523.
Hoesel, B., and J.A. Sahmid. 2013. The complexity of NF-κB signaling in inflammation and cancer. Molecular Cancer 12: 86.
Huang, Y.C. 2014. Outdoor air pollution: a global perspective. Journal of Occupational and Environmental Medicine 56 (Suppl 10): S3–S7.
Kampfrath, T., A. Maiseyeu, Z. Ying, Z. Shah, J.A. Deiuliis, X. Xu, N. Kherada, R.D. Brook, K.M. Reddy, N.P. Padture, S. Parthasarathy, L.C. Chen, S. Moffatt-Bruce, Q. Sun, H. Morawietz, and S. Rajagopalan. 2011. Chronic fine particulate matter exposure induces systemic vascular dysfunction via NADPH oxidase and TLR4 pathways. Circulation Research 108 (6): 716–726.
Kawai, T., and S. Akira. 2010. The role of pattern-recognition receptors in innate immunity: update on toll-like receptors. Nature Immunology 11 (5): 373–384.
Keogh, R.J. 2010. New technology for investigating trophoblast function. Placenta 31 (4): 347–350.
Li, N., C. Sioutas, A. Cho, D. Schmitz, C. Misra, J. Sempf, M. Wang, T. Oberley, J. Froines, and A. Nel. 2003. Ultrafine particulate pollutants induce oxidative stress and mitochondrial damage. Environmental Health Perspectives 111 (4): 455–460.
Roy, A., W. Hu, F. Wei, L. Korn, R.S. Chapman, and J.J. Zhang. 2012. Ambient particulate matter and lung function growth in Chinese children. Epidemiology 23 (3): 464–472.
Slanina, H., A. Konig, H. Claus, M. Frosch, and A. Schubert-Unkmeir. 2011. Real-time impedance analysis of host cell response to meningococcal infection. Journal of Microbiological Methods 84 (1): 101–108.
Takeuchi, O., and S. Akira. 2010. Pattern recognition receptors and inflammation. Cell 140 (6): 805–820.
Xing, Y.F., Y.H. Xu, M.H. Shi, and Y.X. Lian. 2016. The impact of PM2.5 on the human respiratory system. Journal of Thoracic Disease 8 (1): E69–E74.
Yan, G., Q. Du, X. Wei, J. Miozzi, C. Kang, J. Wang, X. Han, J. Pan, H. Xie, J. Chen, and W. Zhang. 2018. Application of real-time cell electronic analysis system in modern pharmaceutical evaluation and analysis. Molecules 23 (12): E3280.
Yin, J., W. Xia, J. Li, C. Guo, Y. Zhang, S. Huang, Z. Jia, and A. Zhang. 2017. COX-2 mediates PM2.5-induced apoptosis and inflammation in vascular endothelial cells. American Journal of Translational Research 9 (9): 3967–3976.
Zhang, J., X. Zeng, Y. Li, W. Zhao, Z. Chen, Q. Du, F. Zhou, N. Ji, and M. Huang. 2019. Exposure to ambient particles alters the evolution of macrophage phenotype and amplifies the inducible release of Eotaxin-1 in allergen-sensitized mice. Journal of Biomedical Nanotechnology 15 (2): 382–395.
Zhong, Y., J. Liao, Y. Hu, Y. Wang, C. Sun, C. Zhang, and G. Wang. 2019. PM2.5 upregulates MicroRNA-146a-3p and induces M1 polarization in RAW264.7 cells by targeting Sirtuin1. International Journal of Medical Sciences 16 (3): 384–393.
This work was supported by the National Natural Science Foundation of China (Grant Numbers 81673672, 81673645, 81873047, and 81573677) and Natural Science Foundation of Zhejiang Province (Grant Numbers LQ17H030006).
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Fu, H., Liu, X., Li, W. et al. PM2.5 Exposure Induces Inflammatory Response in Macrophages via the TLR4/COX-2/NF-κB Pathway. Inflammation (2020). https://doi.org/10.1007/s10753-020-01269-y