Purpose

Herpes simplex keratitis (HSK), caused by type 1 herpes simplex virus (HSV) reactivation, is a severe infectious disease that leads to vision loss. HSV can trigger metabolic reprogramming in the host cell and change the extracellular vesicles (EV) cargos; however, little is known about the EV metabolic signatures during ocular HSV infection. Here, we aimed to depict the EV-associated metabolic landscape in HSK patients’ tears.

Methods

We collected 82 samples from 41 participants with unilateral HSK (contralateral unaffected tears were set as negative control), including subtype cohorts of 13 epithelial, 20 stromal, and 8 endothelial HSK. We isolated tear EVs via our previously established platform and conducted metabolic analysis using LC-MS/MS. The metabolic signatures for recognizing HSK and subtypes were assessed through differential analysis and machine learning algorithms.

Results

Hypopsia and increased extracellular CD63 levels were observed in affected eyes. We identified 339 metabolites based on sEVs isolated from tears. Differential analysis revealed alterations in energy and amino acid metabolism, as well as the infectious microenvironment. Furthermore, we observed dysregulated metabolite such as methyldopa, which is associated with inappropriate neovascularization and corneal sensation loss, contributing to the HSK severity particularly in the stromal subtype. Moreover, machine learning classification also suggested a set of EV metabolic signatures that have potential for pan-keratitis detection.

Conclusions

Our findings demonstrate that tear EV metabolites can serve as valuable indicators for comprehending the underlying pathological mechanisms. This knowledge is expected to facilitate the development of liquid biopsy means and therapeutic target discovery.

中文翻译：

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单纯疱疹性角膜炎引起的泪液细胞外囊泡的代谢特征

目的

单纯疱疹性角膜炎(HSK) 由 1 型单纯疱疹病毒 (HSV) 重新激活引起，是一种导致视力丧失的严重传染病。HSV 可以触发宿主细胞中的代谢重编程并改变细胞外囊泡 (EV) 的货物；然而，人们对眼部 HSV 感染期间 EV 代谢特征知之甚少。在这里，我们的目的是描绘 HSK 患者眼泪中与 EV 相关的代谢情况。

方法

我们从 41 名单侧 HSK 参与者中收集了 82 份样本（对侧未受影响的眼泪设为阴性对照），其中包括 13 名上皮 HSK、20 名基质 HSK 和 8 名内皮 HSK 亚型队列。我们通过之前建立的平台分离了泪液 EV，并使用 LC-MS/MS 进行代谢分析。通过差异分析和机器学习算法评估识别 HSK 和亚型的代谢特征。

结果

在受影响的眼睛中观察到视力减退和细胞外 CD63 水平升高。我们根据从眼泪中分离出的 sEV 鉴定出了 339 种代谢物。差异分析揭示了能量和氨基酸代谢以及感染性微环境的变化。此外，我们观察到甲基多巴等代谢失调，它与不适当的新血管形成和角膜感觉丧失有关，导致 HSK 严重程度，特别是在基质亚型中。此外，机器学习分类还提出了一组具有全角膜炎检测潜力的 EV 代谢特征。

结论

我们的研究结果表明，泪液 EV 代谢物可以作为理解潜在病理机制的有价值的指标。这些知识有望促进液体活检手段的发展和治疗靶点的发现。