Departamento de Microbiologia Geral, Laboratório de Química Biológica de Microrganismos, Instituto de Microbiologia Paulo de Góes, Centro de Ciências da Saúde, Universidade Federal do Rio de Janeiro (UFRJ), Ilha do Fundão, Rio de Janeiro, RJ, 21941-902, Brazil.
Departamento de Análises Clinicas e Toxicológicas, Faculdade de Ciências Farmacêuticas -USP, São Paulo, Brazil.
BMC Microbiol. 2020 Aug 6;20(1):245. doi: 10.1186/s12866-020-01931-3.
Peptidorhamnomannan is a glycoconjugate that consists of a peptide chain substituted by O- and N-linked glycans, present on the cell surface of Lomentospora prolificans, a saprophytic fungus which is widely distributed in regions with temperate climates. O-linked oligosaccharides from peptidorhamnomannan isolated from Lomentospora prolificans conidia are recognized by macrophages mediating macrophage - conidia interaction. In this work, peptidorhamnomannan was isolated from L. prolificans mycelium cell wall and its role in macrophage - Candida albicans interaction was evaluated.
Purified peptidorhamnomannan inhibits the reactivity of rabbit immune sera to mycelial and conidia forms of L. prolificans, indicating that this glycoconjugate is exposed on the fungal surface and can mediate interaction with host immune cells. We demonstrated that peptidorhamnomannan leads to TNF-α production in J774 macrophages for 1, 2 and 3 h of incubation, suggesting that this glycoconjugate may have a beneficial role in the response to fungal infections. In order to confirm this possibility, the effect of peptidorhamnomannan on the macrophage - C. albicans interaction was evaluated. Macrophages treated with peptidorhamnomannan led to a lower fungal survival, suggesting that peptidorhamnomannan induces an increased fungicidal activity in macrophages. Furthermore, TNF-α levels were measured in supernatants after macrophage - C. albicans interaction for 1, 2 and 3 h. Peptidorhamnomannan treatment led to a higher TNF-α production at the beginning of the interaction. However, the release of TNF-α was not maintained after 1 h of incubation. Besides, peptidorhamnomannan did not show any inhibitory or fungicidal effect in C. albicans when used at 100 μg/ml but it was able to kill C. albicans at a concentration of 400 μg/ml.
We suggest that peptidorhamnomannan acts as a molecular pattern on the invading pathogen, promotes TNF-α production and, thus, increases macrophage fungicidal activity against Candida albicans.
肽蕈糖脂是一种糖缀合物，由连接到 N-和 O-糖链上的肽链组成，存在于广泛分布于温带地区的腐生真菌旺盛蕈属的细胞表面。从旺盛蕈属分生孢子中分离出的肽蕈糖脂的 O-连接寡糖被巨噬细胞识别，介导巨噬细胞-分生孢子相互作用。在这项工作中，从旺盛蕈属菌丝细胞壁中分离出肽蕈糖脂，并评估其在巨噬细胞-白色念珠菌相互作用中的作用。
纯化的肽蕈糖脂抑制兔免疫血清对旺盛蕈属菌丝和分生孢子形式的反应，表明该糖缀合物暴露在真菌表面，并能介导与宿主免疫细胞的相互作用。我们证明，肽蕈糖脂在 J774 巨噬细胞中诱导 TNF-α 的产生，在 1、2 和 3 小时的孵育时间内，提示该糖缀合物可能在对抗真菌感染的反应中具有有益的作用。为了证实这一可能性，评估了肽蕈糖脂对巨噬细胞-白色念珠菌相互作用的影响。用肽蕈糖脂处理的巨噬细胞导致真菌存活率降低，提示肽蕈糖脂诱导巨噬细胞中增强的杀菌活性。此外，在巨噬细胞-白色念珠菌相互作用后 1、2 和 3 小时测量上清液中的 TNF-α 水平。肽蕈糖脂处理在相互作用开始时导致 TNF-α 的产生增加。然而，在孵育 1 小时后，TNF-α 的释放没有得到维持。此外，当以 100μg/ml 使用时，肽蕈糖脂对白色念珠菌既没有抑制作用也没有杀菌作用，但它能够在 400μg/ml 的浓度下杀死白色念珠菌。
我们认为肽蕈糖脂作为入侵病原体的模式分子，促进 TNF-α 的产生，从而增加巨噬细胞对白色念珠菌的杀菌活性。
