School of Ophthalmology and Optometry and Eye Hospital, Wenzhou Medical University, Wenzhou, Zhejiang, China.
State Key Laboratory of Optometry, Ophthalmology, and Vision Science, Wenzhou, Zhejiang, China.
Invest Ophthalmol Vis Sci. 2022 Jul 8;63(8):2. doi: 10.1167/iovs.63.8.2.
Scleral hypoxia is a key factor that induces hypoxia-inducible factor-1α (HIF-1α) upregulation, and this response contributes to myopia progression. Currently, we aim to determine if the different HIF subtypes, including HIF-1α and HIF-2α, mediate hypoxia-induced myopia development through promoting scleral MMP-2 expression and collagen degradation.
Our study included: (1) time-course of scleral HIF-2α, MMP-2, and COL1α1 expression during form-deprivation myopia (FDM) development was determined in C57BL/6J mice. (2) The effect of silencing either HIF-1Α or HIF-2A on hypoxia-induced alterations in MMP-2 expression was analyzed in cultured human scleral fibroblasts (HSFs) under a hypoxic condition (i.e. 1% oxygen). (3) To knock-down either HIF-1α or HIF-2α expression in the sclera, we performed Sub-Tenon's capsule injection of an adeno-associated virus (AAV)8-packaged Cre overexpression vector (AAV8-Cre) in HIF-1αfl/fl or HIF-2αfl/fl mice. HIF-1α, HIF-2α, MMP-2, and COL1α1 expression were analyzed by Western blot or quantitative real-time PCR (qRT-PCR). In addition, the effects of scleral HIF-2α knock-down on normal refractive development and FDM development were evaluated.
The time-dependent increases in scleral HIF-2α mimicked the HIF-1α expression profiles as we previously described. Hypoxia significantly promoted MMP-2 expression in HSFs, and this upregulation was solely alleviated by HIF-2A rather than HIF-1A silencing. Scleral HIF-2α knockdown significantly inhibited form-deprivation (FD)-induced MMP-2 upregulation and declines in COL1α1 accumulation and myopia development. Although scleral HIF-1α knockdown also significantly suppressed FD-induced declines in COL1α1 accumulation, it did not abrogate scleral MMP-2 upregulation.
HIF-2α rather than HIF-1α induces myopia development through upregulating MMP-2 and promoting collagen degradation in the sclera.
巩膜缺氧是诱导缺氧诱导因子-1α（HIF-1α）上调的关键因素，这种反应有助于近视进展。目前，我们旨在确定不同的 HIF 亚型，包括 HIF-1α和 HIF-2α，是否通过促进巩膜 MMP-2 表达和胶原降解来介导缺氧诱导的近视发展。
我们的研究包括：（1）在 C57BL/6J 小鼠中确定形觉剥夺性近视（FDM）发展过程中巩膜 HIF-2α、MMP-2 和 COL1α1 表达的时间进程。（2）在缺氧条件下（即 1%氧气），分析沉默 HIF-1Α 或 HIF-2A 对培养的人巩膜成纤维细胞（HSFs）中 MMP-2 表达的缺氧诱导改变的影响。（3）为了在巩膜中敲低 HIF-1α 或 HIF-2α 的表达，我们在 HIF-1αfl/fl 或 HIF-2αfl/fl 小鼠中进行了腺相关病毒（AAV）8 包装的 Cre 过表达载体（AAV8-Cre）的经Tenon 囊下注射。通过 Western blot 或定量实时 PCR（qRT-PCR）分析 HIF-1α、HIF-2α、MMP-2 和 COL1α1 的表达。此外，还评估了巩膜 HIF-2α 敲低对正常屈光发育和 FDM 发展的影响。
巩膜 HIF-2α 的时程增加与我们之前描述的 HIF-1α 表达谱相吻合。缺氧显著促进 HSFs 中 MMP-2 的表达，而这种上调仅被 HIF-2A 而不是 HIF-1A 的沉默所缓解。巩膜 HIF-2α 敲低显著抑制了形觉剥夺（FD）诱导的 MMP-2 上调以及 COL1α1 积累和近视发展的下降。尽管巩膜 HIF-1α 敲低也显著抑制了 FD 诱导的 COL1α1 积累下降，但它并没有消除巩膜 MMP-2 的上调。
HIF-2α 而不是 HIF-1α 通过上调 MMP-2 并促进巩膜中的胶原降解来诱导近视发展。
