Department of Immunology, Shahid Beheshti University of Medical Science, Tehran, Iran.
Arch Med Res. 2011 Oct;42(7):572-6. doi: 10.1016/j.arcmed.2011.11.005. Epub 2011 Dec 5.
Chitin microparticles (CMPs) are found to be potent macrophage stimulators; however, their immunomodulatory effects on the parasite-infected macrophages have not yet been studied. To address this issue, we used a Leishmania major-infected murine macrophage model and characterized the regulatory effects of CMPs on the parasite-infected cells.
Mouse peritoneal macrophages were prepared and infected with L. major (MRHO/IR/1975/ER) standard strain. Following cell treatment with CMPs (500 μg/mL) for 48 h, percent of infected macrophages was determined by Giemsa staining and compared with untreated cells. To find the potential mechanisms of the activity of CMPs, TNF-α and accumulated nitrite in the culture supernatants of the treated and untreated cells were also measured by ELISA and colorimetric Griess assays, respectively.
According to the obtained results, chitin microparticles reduced the ex vivo parasite infectivity by ∼12%. However, this inhibitory effect was not directly related to the increased biosynthesis and release of nitric oxide (NO) by macrophages. Instead, we observed a significant increase in the level of TNF-α secretion due to cell treatment with CMPs. Interestingly, this overexpression of TNF-α did not impair cell viability, suggesting the anti-apoptotic effects of the CMPs.
These findings show that chitin microparticles have immunomodulatory effects on L. major-infected macrophages and further provide motivations for future studies on their in vivo effects.
壳聚糖微粒（CMPs）被发现是强有力的巨噬细胞刺激物；然而，它们对寄生虫感染的巨噬细胞的免疫调节作用尚未得到研究。为了解决这个问题，我们使用了一种感染利什曼原虫的小鼠巨噬细胞模型，并研究了 CMPs 对寄生虫感染细胞的调节作用。
制备小鼠腹腔巨噬细胞，并感染利什曼原虫（MRHO/IR/1975/ER）标准株。用 CMPs（500μg/ml）处理细胞 48 小时后，通过吉姆萨染色确定感染巨噬细胞的百分比，并与未经处理的细胞进行比较。为了发现 CMPs 活性的潜在机制，还通过 ELISA 和比色格里夫斯测定法分别测量处理和未处理细胞培养上清液中的 TNF-α和累积亚硝酸盐。
根据获得的结果，壳聚糖微粒使体外寄生虫感染率降低了约 12%。然而，这种抑制作用与巨噬细胞中一氧化氮（NO）的生物合成和释放增加没有直接关系。相反，我们观察到由于细胞用 CMPs 处理，TNF-α 的水平显著增加。有趣的是，这种 TNF-α 的过表达不会损害细胞活力，这表明 CMPs 具有抗凋亡作用。
这些发现表明，壳聚糖微粒对感染利什曼原虫的巨噬细胞具有免疫调节作用，并进一步为研究其体内作用提供了动力。
