研究比較明膠兒茶素奈米顆粒披覆玻尿酸和市售人工淚液對大鼠乾眼症及角膜病變的效果

Abstract

乾眼症為犬隻常見的眼科疾病，主要可以分為淚水品質不良與淚水產量不足這兩 大類。無論是哪一種乾眼症，人工淚液都是主要的治療方向之一，能夠有效地減緩 乾眼症所帶來的症狀與不適。人工淚液的成分有很多類別，當中含玻尿酸的人工淚 液曾經被證實有更好的效果。除了人工淚液與傳統的點眼治療外，近年也有開始發 展出奈米顆粒，其能夠突破眼睛構造的障蔽、增加藥物作用、增加藥物停留時間以 及降低眼藥點藥頻率的特性使得奈米顆粒的使用越來越普遍，當中也包含結合奈 米顆粒與玻尿酸兩者的特性所製造的產品。此實驗希望透過在大鼠摘除眼眶外與 眼眶內的兩個淚腺組織來誘導大鼠的乾眼症模型，並比較不同種類的的人工淚液 與奈米藥物明膠兒茶素奈米顆粒包覆玻尿酸對於乾眼症大鼠角膜之影響。除了較 常用的檢查工具包括眼裂睜開程度、淚液量測試、螢光染色與裂隙燈檢查外，此實 驗也成功納入較先進之檢測儀器，包括光學同調斷層掃描（OCT）與眼表綜合分析 儀（Ocular Surface Analyzer-VET）進行追蹤與評估。實驗結果顯示，透過摘除兩個 淚腺組織成功建立大鼠的乾眼症模型，在術後有明顯較低的淚液量，較小的眼裂， 較短的非侵入性淚膜破開時間，較高程度的角膜不平整性與染色下觀察到較嚴重 的角膜病變。人工淚液與奈米顆粒組都顯示出相較於乾眼症組有較好的臨床表現， 當中奈米顆粒組相較於乾眼症組有較大的眼裂，較長的非侵入性淚膜破開時間與 較低程度的角膜不平整性。組別之間的角膜上皮厚度沒有明顯差異，不過奈米顆粒 組、含聚合物之人工淚液組和和聚合物與玻尿酸之人工淚液組的角膜基質厚度隨 著時間過去沒有顯著的改變。相較於其他人工淚液使用一天三次，奈米顆粒組在這 次實驗只需點一天兩次也能夠達到比人工淚液相似或是更好的效果。在乾眼症的 病患除了可以使用人工淚液改善症狀外，未來可以納入奈米顆粒作為治療選項之 一。

Keratoconjunctivitis sicca (KCS), also known as dry eye syndrome, is a disorder commonly presented in dogs. It is categorized into two main types: qualitative and quantitative KCS. Regardless of the type of KCS, artificial tears are commonly used to relieve KCS-related symptoms. Among different types of artificial tears, those containing hyaluronic acid (HA) has been proved to be of better performance in different objective tests. Other than traditional medical treatment options, the use of nanoparticles has been increasingly more popular as it can overcome certain barriers of drug delivery of traditional eyedrop applications, prolong drug retention time on the cornea and reduce frequency of use. HA is one of the applicable ingredients that can improve performances of nanoparticles. In this experiment, a KCS rat model was established through excision of extraorbital lacrimal gland (ELG) and infraorbital lacrimal gland (ILG). Commercial artificial tears containing different main active ingredients (hyaluronic acid-containing tears, carbomer-containing tears and hyaluronic acid-carbomer-containing tears) were applied to KCS-induced rats. In addition, an antioxidant epigallocatechin gallate, in combination with gelatin and hyaluronic acid, were used to produce nanoparticle eye drops. The efficacy of the artificial tears and gelatin-epigallocatechin gallate with hyaluronic acid nanoparticle (GEH) on the cornea in the KCS rat models was evaluated. In addition to common ophthalmic assessments including palpebral opening, Schirmer’s tear test (STT), fluorescein staining and slit-lamp biomicroscopic examination, advanced tools such as Optical Coherence Tomography (OCT) and Ocular Surface Analyzer-VET (OSA-VET) were also adopted for evaluation of treatment outcomes, which resulted in successful imaging in this experiment. Results showed that KCS rat model was successfully established through excision of ELG+ILG, with significantly lower postsurgery STT values, smaller palpebral opening, shorter non-invasive tear break-up time, higher degrees of corneal irregularity and more severe corneal lesions by fluorescein staining compared to pre-surgery. Treatment groups showed more favorable results compared to KCS group in different examinations. Specifically, GEH group had significantly larger palpebral opening, longer non-invasive break-up time, less corneal irregularity compared to KCS group. While all groups had no significant changes on corneal epithelial thickness observed under OCT, only GEH group, carbomer-containing tears group and hyaluronic acid-carbomer containing tears group showed no significant changes on corneal stromal thickness along time. Even though GEH was only used two times per day other than three times a day in artificial tear groups, the outcome was similar or even better compared to artificial tear groups. It is concluded that other than the use of commercial artificial tears, nanoparticles may be utilized for future treatment options on KCS patients.