Oral subacute polypropylene microplastics administration effect on potential immunotoxicity in ICR mice
Sarina Kusma1, Anju Maharjan2, Manju Acharya2
1Department of Toxicology, Daegu Catholic University Graduate School, Gyeongsan, Republic of Korea.
Abstract:
Exposure to microplastics may be associated with damage of immune system. Polypropylene microplastics (PP-MPs) with a wide range of beneficial applications have not been extensively studied with respect to the immune system. The aim of this investigation is to examine the influence of two different sizes of PP-MPs (5.2 and 23.9 μm diameter) on immune system components in ICR mice. PP-MPs were administered orally to female and male mice at 0 (corn oil vehicle), 500, 1000, or 2000 mg/kg/d for single and daily for 4-week repeated toxicity test, respectively. No significant differences were observed in number of thymic CD4+, CD8+, CD4+CD8+ T lymphocytes, splenic helper T cells, cytotoxic T cells, and B cells. The ratio of interferon-γ to interleukin-4 in culture supernatants from activated splenocytes ex vivo (48 hr) was lower in females which were repeatedly administered with PP-MPs compared to vehicle irrespective of PP-MPs size and dose. In contrast, the opposite trend was observed in males. Production of tumor necrosis factor-α was upregulated in females that were repeatedly exposed to PP-MPs. The serum IgG2a/IgG1 ratio was lowered in female receiving large-size PP-MPs. Data suggest that immune disturbances resulting in predominant type-2 helper T cell reactivity may occur in mice, especially in females, when repeatedly exposed to PP-MPs. Further investigations with longer exposure periods are necessary to determine the immunotoxicities attributed to PP-MPs.
Insights
Polypropylene microplastics (PP-MPs) may alter immune responses, particularly in female mice, by shifting towards type-2 helper T cell reactivity. Further research is needed to confirm these immunotoxic effects.
Area of Science:
- Environmental Science
- Immunology
- Toxicology
Background:
- Microplastic exposure is a growing concern for environmental and human health.
- Polypropylene microplastics (PP-MPs) have widespread applications but their impact on the immune system is not well understood.
- Investigating the immunotoxicity of PP-MPs is crucial for risk assessment.
Purpose of the Study:
- To evaluate the effects of two different sizes of PP-MPs on immune system components in mice.
- To assess potential sex-specific differences in immune responses to PP-MPs.
- To determine the dose-dependent and duration-dependent toxicity of PP-MPs on immune function.
Main Methods:
- Oral administration of PP-MPs (5.2 and 23.9 μm) to ICR mice (female and male) at varying doses (500, 1000, 2000 mg/kg/d).
- Single and 4-week repeated toxicity tests were conducted.
- Analysis of immune cell populations (T lymphocytes, B cells) and cytokine production (IFN-γ, IL-4, TNF-α) from activated splenocytes ex vivo.
- Measurement of serum immunoglobulin ratios (IgG2a/IgG1).
Main Results:
- No significant changes in the counts of thymic T lymphocytes (CD4+, CD8+, CD4+CD8+) or splenic lymphocytes (helper T cells, cytotoxic T cells, B cells).
- Repeated PP-MP administration lowered the IFN-γ/IL-4 ratio in female mice, indicating a shift towards type-2 helper T cell responses, while males showed the opposite trend.
- Tumor necrosis factor-α production was upregulated in females exposed to PP-MPs.
- The serum IgG2a/IgG1 ratio decreased in females receiving large-sized PP-MPs.
Conclusions:
- Repeated exposure to PP-MPs may induce immune disturbances, characterized by a predominant type-2 helper T cell reactivity, especially in female mice.
- The size and dose of PP-MPs might influence the observed immunomodulatory effects.
- Longer exposure studies are necessary to fully elucidate the immunotoxic potential of PP-MPs.
