奈米脂微粒包覆Dexamethasone對Raw 264.7細胞之影響

Abstract

Dexamethasone為一種合成的類葡萄糖皮質素 (Glucocorticoid)，在臨床上，dexamethasone具有抗發炎、治療自體免疫病 (autoimmune disease) 或是治療血癌，甚至是改善術後症狀。但是在治療上，長期使用這類藥物會產生代謝上異常以及高血壓 (hypertension)、血脂異常 (dyslipidaemia)等副作用，如何達到療效且降低劑量和副作用即成為了問題。先前文獻指出，奈米粒子包覆dexamethasone後，具有保護藥物和促進藥物功能的效用，且奈米脂微粒本身具有生物相容性高、低毒性和在攜帶藥物達到效用後，能被生物體代謝的優點。 本實驗利用膽固醇構造的脂質GCC包覆dexamethasone，確定粒徑和均質度最佳的莫耳比例 (1 : 1 : 1) 後，以HPLC分析GCC_Dex的包覆率，其值約為68 %。分析脂多醣 (lipopolysaccharide, LPS) (100 ng/ml) 和酵母多醣 (zymosan) (25 μg/ml) 刺激Raw 264.7細胞在不同時間點的TNF-α和MCP-1濃度，結果為兩者刺激的分泌量相近。在降低Raw 264.7細胞分泌發炎因子TNF-α和MCP-1的實驗中，當LPS和zymosan先處理Raw 264.7細胞2小時，以PBS洗滌後，再以GCC、dexamethasone和GCC_Dex處理細胞22小時，結果顯示GCC本身並無降低TNF-α和MCP-1分泌量的效果，其中LPS處理的組別中，GCC_Dex相對於dexamethasone的處理，減少了約20 % (TNF-α) 和25 % (MCP-1) 的分泌量。而在zymosan處理的組別中，則減少了約30 % (TNF-α) 和 25 % (MCP-1) 的分泌量。另一方面，當GCC、dexamethasone和GCC_Dex先處理Raw 264.7細胞1小時，以PBS洗滌後，LPS和zymosan處理細胞4小時，再以PBS洗滌，繼續培養至第24小時，結果顯示GCC、dexamethasone和GCC_Dex處理的組別其TNF-α和MCP-1分泌量並無差異。 本篇初步研究發現將dexamethasone包覆於奈米脂微粒GCC中，可增強dexamethasone降低發炎因子TNF-α和MCP-1分泌量的效果，未來配合其他修飾延長在體內時間和釋放時間，有希望應用於長期治療疾病，降低劑量和副作用。

Dexamethasone is a synthetic glucocorticoid. On clinical application, dexamethasone with the properties of anti-inflammation could treat autoimmune diseases. It also could be chemotherapeutic drugs to treat leukemia. But long-term usages of dexamethasone often produce the side effects such as metabolism dysfunction, hypertension or dyslipidaemia. How to achieve the effective goal and reduce the dose and side effects is a problem. According to the reference, encapsulation of dexamethasone into nanoparticles could improve the effects on anti-inflammation and lipid nanoparticles possess the advantages of high biocompatible and low toxicity. In this study, dexamethasone was encapsulated into cholesterol-based nanoparticle GCC and the optimal ratio of GEC-cholesterol : cholesterol : dexamethasone was 1 : 1 : 1. The encapsulation efficiency (EE %) was measured by HPLC and the value was approximately 68 %. In the pro-inflammatory factors secretion experiment, the TNF-α and MCP-1 secretion of Raw 264.7 cells treated with LPS or zymosan showed similar results. Raw 264.7 cells treated with LPS followed by GCC did not reduce the TNF-α and MCP-1 secretion compared to LPS treatment but GCC_Dex reduced the TNF-α (approximately 20 %) and MCP-1 (approximately 30 %) secretion compared to dexamethasone treatment. Resemblance to LPS, Raw 264.7 cells treated with zymosan followed by GCC did not reduce the TNF-α and MCP-1 secretion compared to zymosan treatment alone but GCC_Dex approximately reduced the TNF-α (30 %) and MCP-1 (25 %) secretion, compared to dexamethasone treatment. These findings showed that encapsulation dexamethasone into lipid nanoparticles could reduce TNF-α and MCP-1 secretion. With chemical modification of nanoparticles in the future to prolong the circulation time in blood and drug release time will have the potential on long-term disease control with lower dosage.