Markoulli Maria, You Jingjing, Kim Juno, Duong Carmen L, Tolentino Jonathan B, Karras Joshua, Lum Edward
*PhD, MOptom, FAAO †PhD ‡PhD, BSci(Psychol) §BOptom(Hons), BSci ∥BSci(VisSci) **PhD, BOptom, FAAO School of Optometry and Vision Science, University of New South Wales, Sydney, New South Wales, Australia (MM, JY, JK, CLD, JBT, JK, EL); and Save Sight Institute, Sydney Medical School, University of Sydney, Sydney, New South Wales, Australia (MM, JY).
Optom Vis Sci. 2017 Jul;94(7):726-731. doi: 10.1097/OPX.0000000000001096.
This work aims to characterize the relationship between tear film neuropeptide substance P and the structural integrity of the sub-basal nerve plexus in diabetes.
Seventeen healthy control participants and nine participants with diabetes were recruited in this cross-sectional study. Total protein content and substance P concentrations were determined in the flush tears of participants. Corneal nerve morphology was assessed by capturing the corneal sub-basal nerve plexus using the Heidelberg Retinal Tomograph II with the Rostock Corneal Module (Heidelberg Engineering GmbH, Heidelberg, Germany) in the central cornea. Corneal nerve fiber density (CNFD) was measured using ACCMetrics (M.A. Dabbah, Imaging Science and Biomedical Engineering, Manchester, UK) on eight captured images. Comparisons between groups were made using independent samples t-tests. Correlations between parameters were analyzed using Pearson's correlations.
Substance P concentrations were significantly higher in the tears of the control group compared to participants with diabetes (4150 ± 4752 and 1473 ± 1671 pg/mL, respectively, P = .047). There was no significant difference in total protein content between the groups (3.4 ± 1.8 and 2.6 ± 1.7 mg/mL in the control and diabetes groups, respectively, P = .262). CNFD was significantly lower in the participants with diabetes compared to the control group (16.1 ± 5.7 and 21.5 ± 7.0 mm/mm, respectively, P = .041). There was a moderate correlation between substance P and CNFD (r = 0.48, P = .01).
Substance P is expressed at a significantly lower level in the tears of people with diabetes compared with healthy controls. The positive correlation between substance P and corneal nerve density indicates that substance P may be a potential biomarker for corneal nerve health.
本研究旨在明确泪膜神经肽P物质与糖尿病患者基底神经丛结构完整性之间的关系。
本横断面研究招募了17名健康对照者和9名糖尿病患者。测定参与者冲洗泪液中的总蛋白含量和P物质浓度。使用配备罗斯托克角膜模块的海德堡视网膜断层扫描仪II（德国海德堡海德堡工程有限公司）在中央角膜捕捉角膜基底神经丛，评估角膜神经形态。使用ACCMetrics（英国曼彻斯特成像科学与生物医学工程公司M.A. Dabbah）在8张捕捉图像上测量角膜神经纤维密度（CNFD）。采用独立样本t检验进行组间比较。使用Pearson相关性分析参数之间的相关性。
与糖尿病患者相比，对照组泪液中P物质浓度显著更高（分别为4150±4752和1473±1671 pg/mL，P = 0.047）。两组间总蛋白含量无显著差异（对照组和糖尿病组分别为3.4±1.8和2.6±1.7 mg/mL，P = 0.262）。与对照组相比，糖尿病患者的CNFD显著更低（分别为16.1±5.7和21.5±7.0 mm/mm，P = 0.041）。P物质与CNFD之间存在中度相关性（r = 0.48，P = 0.01）。
与健康对照者相比，糖尿病患者泪液中P物质的表达水平显著更低。P物质与角膜神经密度之间的正相关表明，P物质可能是角膜神经健康的潜在生物标志物。
