Background The macrophage lineage is characterized by plasticity due to the acquisition of distinct functional phenotypes, and two major subsets are evaluated; classical M1 activation (strong microbicidal activity) and alternative M2 activation (immunoregulatory functions). The M1 subset expresses inducible nitric oxide synthase (iNOS), which is a primary marker to identify these cells, whereas M2 macrophages are characterized by expression of Arginase-1, found in inflammatory zone 1 (Fizz1), chitinase-like molecule (Ym-1), and CD206. The micro-environmental stimuli and signals in tissues are critical in the macrophage polarization. Toll-like receptors (TLR) ligands, such as lipopolysaccharide (LPS), palmitoyl-3-cysteine-serine-lysine-4 (Pam3CSK4), and ArtinM (mannose-binding lectin) are inductors of M1 subset. The impact of TLR2 and TLR4 signals to fight against Cryptococcus gattii infection is unknown, which is a fungal pathogen that preferentially infects the lung of immunocompetent individuals. The macrophages initiate an immune response to combat the C. gattii, then we evaluated in RAW 264.7 cell the effect of TLR2 and TLR4 agonists on the macrophage polarization dynamic and the impact on the growth of C. gattii. Methods and Results We demonstrated that P3C4, LPS, and ArtinM induced an increase in the levels of iNOS transcripts in RAW 264.7 cells, whereas the relative expression of arginase-1, Ym-1, and Fizz1 was significantly increased in the presence of IL-4 alone. The effects of TLR2 and TLR4 agonists on repolarization from the M2 to M1 subset was evaluated, and the first stimulus was composed of IL-4 and, after 24 h of incubation, the cells were submitted to a second stimulus of P3C4, LPS, ArtinM, or Medium. These TLR agonists induced the production of TNF-α in polarized RAW 264.7 cells to the M2 subset, moreover the measurement of M1/M2 markers using qRT-PCR demonstrated that a second stimulus with LPS for 24 h induced a significant augmentation of levels of iNOS mRNA. This impact of TLR2 and TLR4 agonists in the activation of the RAW 264.7 macrophage was assayed in the presence of C. gattii, the macrophages stimulated with TLR2 and TLR4 agonists for 24 h and co-cultured with C. gattii, as a second stimulus, reached high levels of TNF-α even after incubation with different concentrations of C. gattii. The activation of RAW 264.7 cells induced by TLR2 and TLR4 agonists favored the phagocytosis of C. gattii and inhibited the growth of yeast in the early period of infection. However, RAW 264.7 cells incubated with C. gattii in the presence of TLR2 and TLR4 agonists did not result a significant difference in the colony forming unit (CFU) assay in the early period of C. gattii infection, compared to negative control. Conclusion Polarized RAW 264.7 cells to the M1 subset with TLR2 and TLR4 agonists did not inhibit the growth of C. gattii, whereas robust immunity was identified that could dysregulate host tolerance to this pathogen.

中文翻译：

---

LPS 和 Pam3CSK4 在 RAW 264.7 细胞中确保的促炎反应并未改善对加特隐球菌感染的抑菌作用

背景 由于获得了不同的功能表型，巨噬细胞谱系的特点是可塑性，并评估了两个主要亚群；经典 M1 激活（强杀菌活性）和替代 M2 激活（免疫调节功能）。M1 亚群表达诱导型一氧化氮合酶 (iNOS)，它是识别这些细胞的主要标志物，而 M2 巨噬细胞的特点是表达在炎症区 1 (Fizz1) 中发现的精氨酸酶-1，几丁质酶样分子 (Ym- 1) 和 CD206。组织中的微环境刺激和信号对巨噬细胞极化至关重要。Toll 样受体 (TLR) 配体，例如脂多糖 (LPS)、棕榈酰-3-半胱氨酸-丝氨酸-赖氨酸-4 (Pam3CSK4) 和 ArtinM（甘露糖结合凝集素）是 M1 亚群的诱导剂。TLR2 和 TLR4 信号对抗隐球菌感染的影响尚不清楚，隐球菌是一种优先感染免疫功能正常个体肺部的真菌病原体。巨噬细胞启动免疫反应以对抗 C. gattii，然后我们在 RAW 264.7 细胞中评估 TLR2 和 TLR4 激动剂对巨噬细胞极化动态的影响以及对 C. gattii 生长的影响。方法和结果 我们证明 P3C4、LPS 和 ArtinM 诱导 RAW 264.7 细胞中 iNOS 转录物水平的增加，而 arginase-1、Ym-1 和 Fizz1 的相对表达在 IL-存在下显着增加。 4个人。评估了 TLR2 和 TLR4 激动剂对 M2 到 M1 亚群复极化的影响，第一个刺激物由 IL-4 组成，孵育 24 小时后，细胞接受 P3C4、LPS、ArtinM 或培养基的第二次刺激。这些 TLR 激动剂在极化的 RAW 264.7 细胞中诱导产生 TNF-α 到 M2 亚群，此外，使用 qRT-PCR 测量 M1/M2 标记表明，用 LPS 进行 24 小时的第二次刺激诱导 iNOS 水平显着增加mRNA。TLR2 和 TLR4 激动剂在 RAW 264.7 巨噬细胞活化中的这种影响在存在 C. gattii 的情况下进行了测定，用 TLR2 和 TLR4 激动剂刺激巨噬细胞 24 小时并与 C. gattii 共培养，作为第二种刺激，即使在与不同浓度的 C. gattii 孵育后也达到了高水平的 TNF-α。TLR2和TLR4激动剂诱导的RAW 264.7细胞的活化有利于C. gattii的吞噬作用，并在感染早期抑制酵母菌的生长。然而，与阴性对照相比，在存在 TLR2 和 TLR4 激动剂的情况下，与 C. gattii 一起孵育的 RAW 264.7 细胞在 C. gattii 感染早期的菌落形成单位 (CFU) 测定中没有产生显着差异。结论 使用 TLR2 和 TLR4 激动剂将 RAW 264.7 细胞极化至 M1 亚群不会抑制 C. gattii 的生长，而确定的强免疫可能会失调宿主对该病原体的耐受性。