Tear fluid, also referred to as tears or tear film, is an important biological fluid that plays a key role in maintaining ocular surface health and immune homeostasis. Recent studies have found that tear fluid not only participates in the occurrence and development of ocular diseases, but also exerts profound effects in the immune pathological mechanisms of systemic diseases, breaking through the inherent understanding previously held by the scientific community. Immune cells in tear fluid (such as T cells, neutrophils, natural killer cells, macrophages), cytokines, and immunoglobulins can specifically participate in autoimmune diseases (such as Sjögren's syndrome, rheumatoid arthritis, systemic lupus erythematosus, multiple sclerosis, Graves' ophthalmopathy) and systemic diseases (such as Alzheimer's disease, diabetes mellitus, graft-versus-host disease). The dynamic changes in tear fluid components can reflect systemic immune homeostasis imbalance. Tear fluid biomarkers, such as exosomal microRNA (miR)-204, miR-200b-5p, and the protein marker β2-microglobulin, have shown great potential in early disease screening, diagnostic stratification, and therapeutic target discovery. Tear fluid immune component analysis may provide innovative diagnostic tools and therapeutic targets for systemic diseases. Future research should focus on promoting the standardization and clinical transformation of tear fluid testing technologies and their clinical application.
泪液(或称眼泪、泪膜)作为一种重要的体液，对维持眼表的健康及免疫稳态具有关键作用。近年研究发现，泪液不仅参与眼部疾病的发生和发展，更在系统性疾病的免疫病理机制中发挥了深层作用，突破了既往科学界的固有认知。泪液中的免疫细胞(如T细胞、中性粒细胞、自然杀伤细胞、巨噬细胞)、细胞因子及免疫球蛋白可特异性地参与自身免疫性疾病(如干燥综合征、类风湿关节炎、系统性红斑狼疮、多发性硬化、Graves眼病)和系统性疾病(如阿尔茨海默病、糖尿病、移植物抗宿主病)。泪液成分的动态变化可反映全身免疫稳态失衡，其生物标志物(如外泌体携带的微RNA(microRNA，miR)-204、miR-200b-5p，蛋白质标志物β2微球蛋白等)在疾病早期筛查、诊断分层及治疗靶点发现方面展现出巨大潜力。泪液免疫成分分析可为系统性疾病提供创新性的诊断工具和治疗靶点，未来研究应致力于推动泪液检测技术的标准化与临床应用转化。.
Keywords: autoimmune disease; exosomes; immunity; microRNAs; ocular surface immune microenvironment; tear fluid.