Hee-Yeon Kim a,b,1, Janbolat Ashim c,1, Song Park a,c,1, Wansoo Kim d,e, Sangho Ji c, Seoung-Woo Lee a,e, Yi-Rang Jung f, Sang Won Jeong e, Se-Guen Lee e, Hyun-Chul Kim e, Young-Jae Lee e, Mi Kyung Kwon e, Jun-Seong Hwang e, Jung Min Shin e, Sung-Jun Lee e, Wookyung Yu a,c, Jin-Kyu Park b, Seong-Kyoon Choi a,e,1
aCore Protein Resources Center, DGIST, Daegu, Republic of Korea
bCollege of Veterinary Medicine, Kyungpook National University, Daegu, 41566, Republic of Korea
cDepartment of Brain Sciences, DGIST, Daegu, Republic of Korea
dSchool of Life Science, BK21 FOUR KNU Creative Bioresearch Group, Kyungpook National University, Daegu, Republic of Korea
eDivision of Biotechnology, DGIST, Daegu, Republic of Korea
fDepartment of Companion Animal Health Management, Daegu Health College, Daegu, Republic of Korea
1These authors contributed equally to this work.
Corresponding authors: Sung-Jun Lee, Wookyung Yu, Jin-Kyu Park, Seong-Kyoon Choi
The growing use of plastic materials has resulted in a constant increase in the risk associated with microplastics (MPs). Ultra-violet (UV) light and wind break down modify MPs in the environment into smaller particles known as weathered MPs (WMPs) and these processes increase the risk of MP toxicity. The neurotoxicity of weathered polystyrene-MPs remains unclear. Therefore, it is important to understand the risks posed by WMPs. We evaluated the chemical changes of WMPs generated under laboratory-synchronized environmentally mimetic conditions and compared them with virgin MPs (VMPs). We found that WMP had a rough surface, slight yellow color, reduced molecular weight, and structural alteration compared with those of VMP. Next, 2 μg of ∼100 μm in size of WMP and VMP were orally administered once a day for one week to C57BL/6 male mice. Proteomic analysis revealed that the WMP group had significantly increased activation of immune and neurodegeneration-related pathways compared with that of the VMP group. Consistently, in in vitro experiments, the human brain-derived microglial cell line (HMC-3) also exhibited a more severe inflammatory response to WMP than to VMP. These results show that WMP is a more profound inflammatory factor than VMP. In summary, our findings demonstrate the toxicity of WMPs and provide theoretical insights into their potential risks to biological systems and even humans in the ecosystem.