Background Sclera remodeling process in axial elongation is one of the main pathological mechanisms of axial myopia progression.Studies confirmed that transforming growth factor-β1(TGF-β1) participates in the sclera remodeling process,and Smad3 is one of TGF-β1 downstream signal gene transcriptive factors,so to explore its role in sclera remodeling process of myopic eyes is of great significance for pathogenesis and prevention research of myopia.Objective This study was to investigate the expressions of type Ⅰ collagen and Smad3,a TGF-31 downstream target,in sclera of form deprivation myopic (FDM) eyes and explore the impact of TGF-β1-Smad3-type Ⅰ collagen signaling pathway on collagen remodeling in myopic sclera.Methods Seventy-five 1-week-old guinea pigs were randomly divided into normal control group (25 guinea pigs) and FDM group (50 guinea pigs).Monocular FDM was induced by occluding the left eyes of guinea pigs in FDM group with translucent latex balloons for 2,4,6 weeks,respectively,and consecutive occluding for 4 weeks followed by uncovering for 1 week (4/-1 weeks).The refractive power was detected by retinoscopy and axial length was measured with A-type ultrasound.Immunohistochemistry and reverse transcription-PCR were employed to detect the dynamic expressions of type Ⅰ collagen and Smad3 protein ad mRNA in the sclera of guinea pigs with emmetropia and experimental myopia,ard the relationship between collagen Ⅰ and Smad3 levels was analyzed.Results The refraction was hypermetropic in both normal control group and FDM group before occluding of eyes (P＞0.05),and the hypermetropic power was gradually reduced over time in the normal control group.In the FDM group,the refractive power was gradually changed from (+2.09 ± 0.31)D before occluding to (-1.23±0.69),(-4.17±0.59),(-7.07±0.56) and (-4.30±0.58)D,and the axial length was increased from (5.93-±0.39)mm to (6.62±0.36),(7.30±0.34),(7.99--0.32),and (7.21 ±0.36) mm at weeks 2,4,6,and 4/-1 after occluding,respectively,indicating significant differences in refractive power and axial length over time in the FDM group from normal control group and self-control group (all at P＜0.05).The expressions of Smad3 and type Ⅰ collagen protein and mRNA in the sclera of the FDM group was significantly lower than those of the control group and self-control group in various time points (all at P＜0.05).The positive correlation were found in the expression of Smad3 on the myopic sclera with that of type Ⅰ collagen in both protein and mRNA levels (protein:r=0.993,P＜0.05;mRNA:r=0.954,P＜0.05).Conclusions The myopic power and ocular axis increase dependent upon occluding time,and the expressions of Smad3 and type Ⅰ collagen in the sclera are correspondingly weakened in FDM eyes.A consistent expression trend is found between Smad3 and type Ⅰ collage,suggesting Smad3 and type Ⅰ collagen participate in the regulation of sclera remodeling in myopia by TGF-β1-Smad3-Collagen Ⅰ signaling pathway.%背景 巩膜重塑过程中导致眼轴的伸长是轴性近视进展的主要病理机制之一.研究证实转化生长因子β1(TGF-β1)参与巩膜重塑过程,而Smad3是TGF-β1的下游信号转录基因之一,探讨其在近视眼巩膜重塑过程中的作用对于近视发病机制和防治研究具有重要意义. 目的 研究近视眼巩膜重塑过程中Smad3和Ⅰ型胶原的表达情况,探讨TGF-β1-Smad3-Collagen Ⅰ信号途径在近视巩膜胶原重塑中的作用.方法 将出生后7d的豚鼠75只任意分为空白对照组(25只)和形觉剥夺性近视(FDM)组(50只).FDM组豚鼠采用半透明乳胶遮盖左眼的方法制备单眼FDM模型,右侧未遮盖眼作为自身对照.FDM组分别遮盖2、4、6周,另一组动物遮盖4周后去遮盖1周,分别于遮盖前及上述时间点采用检影法测量各组豚鼠双眼屈光度,采用A型超声手动模式测量豚鼠眼轴长度.于上述时间点分别处死5只豚鼠并制备巩膜组织切片,分别采用免疫组织化学法及逆转录PCR法检测各组豚鼠巩膜组织中Smad3和Ⅰ型胶原蛋白及其mRNA的相对表达量.结果 遮盖前空白对照组与FDM组豚鼠屈光度均为远视状态,差异无统计学意义(P＞0.05),空白对照组豚鼠远视屈光度逐渐下降,而FDM组豚鼠在遮盖前,遮盖2、4、6周及遮盖4周后去遮盖1周屈光度从(+2.09±0.31)D逐渐改变为(-1.23±0.69)、(-4.17±0.59)、(-7.07±0.56)和(-4.30±0.58)D,眼轴长度从(5.93±0.39)mm逐渐改变为(6.62±0.36)、(7.30±0.34)、(7.99±0.32)和(7.21±0.36) mm,与空白对照组比较,遮盖后各时间点FDM组豚鼠近视度明显升高,眼轴测量值明显增加,差异均有统计学意义(均P＜0.01).与自身对照组比较,遮盖2周、4周、遮盖4周后去遮盖1周及遮盖6周时FDM组近视度均明显升高,眼轴明显增长,差异均有统计学意义(均P＜0.05).遮盖前空白对照组与FDM组豚鼠后极部巩膜组织中Ⅰ型胶原和Smad3蛋白及其mRNA相对表达量的差异均无统计学意义(均P＞0.05),FDM组豚鼠遮盖2、4、6周及遮盖4周后去遮盖1周巩膜组织中Ⅰ型胶原和Smad3蛋白及其mRNA相对表达量均明显低于空白对照组和自身对照组,差异均有统计学意义(均P＜0.05).豚鼠巩膜组织中Ⅰ型胶原蛋白与Smad3蛋白及其mRNA相对表达量均呈明显正相关(蛋白:r=0.993,P＜0.05;mRNA:r =0.954,P＜0.05). 结论 FDM豚鼠模型眼随着遮盖时间的延长近视度明显增加,眼轴明显增长,豚鼠巩膜组织中Smad3和Ⅰ型胶原的表达相应减弱,且Smad3和Ⅰ型胶原表达量的变化趋势高度一致.Smad3和Ⅰ型胶原可能通过TGF-β1-Smad3-Collagen Ⅰ信号途径参与近视眼巩膜重塑过程的调控.
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