Mpakosi Alexandra, Kaliouli-Antonopoulou Christiana
Department of Microbiology, General Hospital of Nikaia "Agios Panteleimon", Piraeus, GRC.
Department of Immunology, General Hospital of Nikaia "Agios Panteleimon", Piraeus, GRC.
Cureus. 2024 Jun 8;16(6):e61954. doi: 10.7759/cureus.61954. eCollection 2024 Jun.
Filamentous fungal keratitis is a particularly serious eye infection that often results in ulceration, corneal perforation, and blindness. The cornea acts as a natural barrier against harmful agents due to the close connection of its epithelial cells. In addition, on its surface, there is a large number of substances with anti-inflammatory and bactericidal properties, such as secretory IgA and mucin glycoproteins, and antimicrobial peptides (AMPs), such as human β-defensin 2 (HBD-2) and LL-37, which are especially increased in filamentous fungal keratitis. The interaction between pathogenic fungi and the host's immune mechanisms is a complex process: pathogen-associated molecular pattern (PAMP) molecules (chitin, β-glucan, and mannan) found in the fungal cell wall are recognized by pattern recognition receptors (PRRs) (toll-like receptors {TLRs}, C-type lectin receptors {CLRs}, nucleotide-binding oligomerization domain-like receptors {NLRs}, and scavenger receptors {SR}) found in host defense cells, triggering the secretion of various types of cytokines, such as interleukins (IL), tumor necrosis factors (TNFs), and chemokines, which recruit macrophages and neutrophils to migrate to the site of infection and activate inflammatory responses. In addition, the interaction of hyphae and corneal epithelial cells can activate cluster of differentiation (CD) 4+ T cells, CD8+ T cells, and B cells and induce secretion of T-helper (Th)-type cytokines 2 (IL-4 and IL-13) and IgG.
丝状真菌性角膜炎是一种特别严重的眼部感染，常导致溃疡、角膜穿孔和失明。由于角膜上皮细胞紧密相连，角膜起到了抵御有害物质的天然屏障作用。此外，在其表面有大量具有抗炎和杀菌特性的物质，如分泌型IgA和粘蛋白糖蛋白，以及抗菌肽（AMPs），如人β-防御素2（HBD-2）和LL-37，在丝状真菌性角膜炎中其含量会特别增加。致病真菌与宿主免疫机制之间的相互作用是一个复杂的过程：真菌细胞壁中发现的病原体相关分子模式（PAMP）分子（几丁质、β-葡聚糖和甘露聚糖）被宿主防御细胞中发现的模式识别受体（PRRs）（Toll样受体{TLRs}、C型凝集素受体{CLRs}、核苷酸结合寡聚化结构域样受体{NLRs}和清道夫受体{SR}）识别，触发各种细胞因子的分泌，如白细胞介素（IL）、肿瘤坏死因子（TNFs）和趋化因子，这些因子招募巨噬细胞和中性粒细胞迁移到感染部位并激活炎症反应。此外，菌丝与角膜上皮细胞的相互作用可激活分化簇（CD）4+T细胞、CD8+T细胞和B细胞，并诱导分泌辅助性T（Th）2型细胞因子（IL-4和IL-13）和IgG。
