폴리에틸렌 테레프탈레이트 미세플라스틱 아급성 경구 노출에 따른 마우스의 면역독성 및 장 조직병리학적 변화 = Immunodysregulatory potentials with histopathological alterations of polyethylene terephthalate microplastics in mice subacutely exposed via intragastric intubation

다국어 초록 (Multilingual Abstract)

Plastics are indispensable materials in modern industry and daily life, among which polyethylene terephthalate (PET) is widely used in bottles, food packaging, and textiles. Due to its high thermal and chemical stability, PET is resistant to environmental degradation and can persist as polyethylene terephthalate microplastics (PET-MPs), posing potential risks to ecosystems and human health.
The present study aimed to evaluate immunotoxicological effects of PET-MPs (SM, single-digit average particle size: 7.5 ㎛, DM, double-digit average particle size: 26.9 ㎛) following single or 28-day repeated oral administration to ICR mice with observation on histopathological changes in the liver, kidney, and colon, as well as alterations in mucin secretion in the colon. Comparative assessments were conducted according to particle size, dose (Low: 500, Middle: 1000, High: 2000 ㎎/㎏ body weight/day), sex, and exposure frequency. The immunotoxicological parameters assessed were body weight gain, splenic and thymic immune cell composition, levels of serum immunoglobulins (IgG1, IgG2a, IgE, IgA), and production of tumor necrosis factor-alpha (TNF-α), interferon-gamma (IFN-γ), interleukin (IL)-4, and IL-13 from ex vivo stimulated splenocytes. Histopathological observations were made on liver, kidney, and colon tissues following hematoxylin & eosin staining and Alcian blue-periodic acid Schiff stain.
The body weight gain was unaffected by PET-MPs, except for significant decreases in males administered low or middle doses of SM PET-MPs compared with the corn oil vehicle control. Viable splenocyte counts were lowered in PET-MPs administration groups, irrespective of PET-MPs size, dose, and sex. No significant differences were observed between groups in the thymic or splenic immune cell populations, including CD4+, CD8+, CD4+/CD8+ T cells and B cells. The serum IgG1/IgG2a ratio was upregulated in female mice dosed with SM and DM size PET-MPs, indicating a predominant type-2 immune response, and the serum IgA level was downregulated in both female and male mice, irrespective of PET-MPs size, suggesting potential alteration in mucosal immunity. The IL-13/IFN-γ ratio was upregulated in female and male mice administered with SM and DM size PET-MPs, except for female mice dosed with SM size PET-MPs, which also implies the PET-MPs mediated skewedness to type-2 immune response. Histopathological examination revealed localized hepatic necrosis and extramedullary hematopoiesis in the liver, while no pathological lesions were observed in the kidney or colon. However, goblet cell staining of the colon demonstrated a dose-dependent increase in mucin secretion in female mice administered with SM size PET-MPs, suggesting activation of epithelial protective mechanisms.
These findings indicate that orally administered PET-MPs can affect the immune system and intestinal mucosal barrier in a size-, dose-, and sex-dependent manner. PET-MPs appear to induce type-2 predominant immune polarization and disrupt mucosal defense mechanisms, underscoring their potential to cause immunotoxic and pathological effects upon chronic exposure.

목차 (Table of Contents)

• (Abstract)
• Ⅰ. 서 론 1
• 1. 연구 배경 1
• 2. 연구 목적 7
• Ⅱ. 연구 방법 8
• 1. 시험물질 8
• 1.1 시험물질의 제조 8
• 1.2 투여량 설정 및 조제 9
• 2. 실험동물 및 사육환경 10
• 2.1 투여방법 및 군구성 11
• 2.2 부검 및 채혈 13
• 3. 분석 항목 14
• 3.1 비장 및 흉선의 단일세포군의 배양 및 T 림프구 활성화 14
• 3.2 마우스 비장과 흉선의 면역세포 구성비 분석 15
• 3.3 마우스의 혈청 내 체액면역 지표치 분석 16
• 3.4 마우스 비장 단일세포 배양액 내 세포면역 지표치 분석 17
• 3.5 마우스 조직병리학적 검사를 위한 표본 제작 18
• 4. 통계학적 분석 19
• Ⅲ. 결과 20
• 1. PET-MPs 반복 투여된 마우스의 생체 내 면역독성학적 변화 20
• 1.1 체중 변화 및 증체량 분석 20
• 1.2 비장 및 흉선의 생존 세포 수 분석 23
• 1.3 비장 및 흉선의 면역세포 구성비 분석 25
• 1.4 혈청 내 체액성 면역 지표치 변화 32
• 1.4.1 IgG isotype 평가 32
• 1.4.2 체액성 면역 지표치의 편향성 평가 35
• 1.4.3 IgE 평가 37
• 1.4.4 IgA 평가 39
• 1.5 비장세포 배양액 내 세포성 면역 지표치의 수준 변화 41
• 1.5.1 TNF-α 평가 41
• 1.5.2 IFN-γ 평가 44
• 1.5.3 IL-4 평가 46
• 1.5.4 IL-13 평가 48
• 1.5.5 세포성 면역 지표치의 편향성 평가 50
• 2. PET-MPs 단회 투여된 마우스의 생체 내 면역독성학적 변화 53
• 2.1 비장 및 흉선의 면역세포 구성비 분석 53
• 2.2 혈청 내 체액성 면역 지표치 변화 58
• 2.2.1 IgG isotype 평가 58
• 2.2.2 IgE 평가 62
• 2.3 비장세포 배양액 내 세포성 면역 지표치의 수준 변화 64
• 2.3.1 TNF-α 및 IFN-γ 평가 64
• 2.3.2 IL-4 및 IL-13 평가 66
• 2.3.3 세포성 면역 지표치의 편향성 평가 68
• 3. PET-MPs 반복 투여된 마우스의 생체 내 조직병리학적 변화 71
• 3.1 간 조직병리학적 소견 71
• 3.2 신장 조직병리학적 소견 75
• 3.3 결장 조직병리학적 소견 77
• Ⅳ. 고 찰 82
• Ⅴ. 결 론 94
• 참고 문헌 96