chang yan zhou

# 肠-眼轴与眼部健康 新兴的**肠-眼轴**概念认识到肠道微生物及其产物可影响眼睛。肠道细菌发酵纤维产生**短链脂肪酸（SCFAs）**（如乙酸、丙酸、丁酸）并修饰胆汁酸（BAs）。这些代谢物进入循环并可到达眼睛，影响其免疫环境和功能 ([pmc.ncbi.nlm.nih.gov](https://pmc.ncbi.nlm.nih.gov/articles/PMC10488056/#:~:text=derived%20metabolites%20involved%20in%20counteracting,the%20bile%20acid))。例如，微生物失调——肠道菌群失衡——已被证实与从年龄相关性黄斑变性、葡萄膜炎到干眼症和青光眼等眼部疾病相关联 ([pmc.ncbi.nlm.nih.gov](https://pmc.ncbi.nlm.nih.gov/articles/PMC10488056/#:~:text=Moreover%2C%20recent%20studies%20underline%20a,better%20management%20of%20these%20diseases))。事实上，最近一项调查发现，肠道失衡与多种眼部疾病相关，且只有少数早期试验（25项研究中的4项）测试了益生菌或粪便移植等干预措施对眼部疾病的影响 ([pmc.ncbi.nlm.nih.gov](https://pmc.ncbi.nlm.nih.gov/articles/PMC10516887/#:~:text=ocular%20pathology,clinical%20trials%20may%20be%20warranted))。这一肠-眼轴表明，肠道来源的SCFAs、BAs，甚至炎症成分（如LPS），都可能调节眼部**免疫张力**（基础免疫状态），并影响小梁网（房水引流过滤器）等组织和眼内压（IOP）。 ## 微生物代谢物与眼部免疫 ### 短链脂肪酸（SCFAs） **SCFAs**是碳原子数少于六个的脂肪酸，主要包括乙酸、丙酸和丁酸，由肠道细菌消化纤维产生。它们全身性地**调节免疫反应** ([www.frontiersin.org](https://www.frontiersin.org/journals/medicine/articles/10.3389/fmed.2024.1377186/full#:~:text=SCFAs%20can%20ameliorate%20immune,often%2C%20metabolites%20and%20inflammation%20go)) ([pmc.ncbi.nlm.nih.gov](https://pmc.ncbi.nlm.nih.gov/articles/PMC10488056/#:~:text=derived%20metabolites%20involved%20in%20counteracting,the%20bile%20acid))。在眼睛中，SCFAs发挥抗炎作用。在小鼠模型中，注射的SCFAs在眼部组织中被检测到，并*减轻*了内毒素（LPS）暴露引起的炎症 ([pubmed.ncbi.nlm.nih.gov](https://pubmed.ncbi.nlm.nih.gov/33617852/#:~:text=responses%20of%20the%20eye%20and,functions%20in%20the%20intraocular%20milieu)) ([pmc.ncbi.nlm.nih.gov](https://pmc.ncbi.nlm.nih.gov/articles/PMC10488056/#:~:text=derived%20metabolites%20involved%20in%20counteracting,the%20bile%20acid))。这表明SCFAs可以通过血液穿过血眼屏障并减轻眼内炎症。例如，在小鼠中腹腔注射丁酸可减弱LPS诱导的葡萄膜炎，减少促炎细胞因子并增强调节性T细胞 ([pubmed.ncbi.nlm.nih.gov](https://pubmed.ncbi.nlm.nih.gov/33617852/#:~:text=responses%20of%20the%20eye%20and,functions%20in%20the%20intraocular%20milieu)) ([pmc.ncbi.nlm.nih.gov](https://pmc.ncbi.nlm.nih.gov/articles/PMC10488056/#:~:text=derived%20metabolites%20involved%20in%20counteracting,the%20bile%20acid))。同样，一项综述指出，全身注射SCFAs后可减轻眼部炎症 ([pmc.ncbi.nlm.nih.gov](https://pmc.ncbi.nlm.nih.gov/articles/PMC10488056/#:~:text=derived%20metabolites%20involved%20in%20counteracting,the%20bile%20acid))。这些抗炎作用表明SCFAs有助于维持健康的**眼部免疫张力**（控制免疫活动）。 相反，肠道来源的**促炎信号**可能损害眼睛。肠道细菌（尤其是革兰氏阴性菌）释放LPS，触发TLR4等先天免疫受体。TLR4信号传导已知会影响小梁网，并与原发性开角型青光眼存在遗传关联 ([www.frontiersin.org](https://www.frontiersin.org/journals/medicine/articles/10.3389/fmed.2024.1377186/full#:~:text=variations%20in%20toll,While%20previous%20sections%20delve))。在动物体内，给予LPS会加剧视网膜神经元损失和光感受器损伤 ([www.frontiersin.org](https://www.frontiersin.org/journals/medicine/articles/10.3389/fmed.2024.1377186/full#:~:text=variations%20in%20toll,While%20previous%20sections%20delve))。因此，平衡的肠道菌群（富含SCFA生产者）支持眼部健康，而失调可能使眼睛充满炎症信号。 ### 胆汁酸 **胆汁酸（BAs）**是肝脏产生的胆固醇衍生物，并由肠道微生物修饰。除了消化脂肪，BAs还是具有抗炎和神经保护作用的信号分子 ([pmc.ncbi.nlm.nih.gov](https://pmc.ncbi.nlm.nih.gov/articles/PMC7920062/#:~:text=Bile%20acids%20,biological%20significance%20in%20the%20e

肠-眼轴：益生菌、代谢物与眼内压

准备检查你的视力了吗？