| 摘要: | 病菌感染、胃酸或異物吸入均會造成肺炎、急性肺損傷 (Acute lung injury, ALI)，魚油富含 EPA (Eicosapentaenoic acid) 與 DHA (Docosahexaenoic Acid)，許多動物試驗均顯示補充魚油可有效改善炎症疾病的病程與預後。克雷伯氏肺炎菌 (Klebsiella pneumoniae, KP) 為院內感染常見的菌種之一，甚至於社區感染病例也漸增，因此本研究利用氣管注入克雷伯氏肺炎菌，作為 ALI 的小鼠疾病模式，探討短期補充魚油對於 KP 菌誘導 ALI 是否有預防病程進展的保護效應。實驗採用 6 至 8 週齡 BALB/c 品系雌鼠，隨機分為兩組，肺炎魚油組、肺炎純水組，魚油每日管餵 150 L (45mg DHA+EPA) 、純水餵食相同體積，連續餵食一週，於第七天餵食後 3 小時由氣管注入 (Intratracheal instillation, IT) 給予 KP 菌 (1×105 CFU/mouse，50 L) 誘發 ALI，第一階段實驗為觀察小鼠存活率。第二階段實驗於誘發 ALI 後4、24、48、72 小時四個時間點犧牲小鼠，採集血液、肺臟及肺泡沖洗液（Bronchoalveolar lavage fluid, BALF)，肺臟進行肺臟組織切片病理檢查，BALF 分析細菌菌量、細胞總量與比例以及發炎相關細胞激素，血液分析細胞激素。結果顯示，肺炎純水組誘導後第六天全數死亡，肺炎魚油組仍有50% 存活率，表示短期補充魚油對於KP菌誘導小鼠 ALI 具有降低死亡率的效應；BALF之發炎相關細胞激素濃度方面，腫瘤壞死因子-α (Tumor necrosis factor alpha, TNF-α) 是發炎前期的指標，在 ALI 第4 小時達到最高峰，細胞介質-6 (Interleukin-6, IL-6)、細胞介質-10 (Interleukin-10, IL-10)、單核細胞趨化蛋白-1 (Monocyte chemoattractant protein-1, MCP-1) 則於24小時之表現量最高，各時間的兩組結果均無顯著差異；總細胞數(Total cell count)於第24小時累積最高，其中多核型白血球 (Polymorphonuclear leukocytes, PMNs) 數量也於此時間點最高，但兩組之間無統計差異，表示魚油並無降低浸潤細胞數的能力；由 BALF 之細菌數分析小鼠感染狀況，四個時間點兩組間亦無統計上顯著性，由此得知短期補充魚油沒有明顯抑制細菌感染的能力。結論：短期補充魚油對於克雷伯氏肺炎菌誘導小鼠 ALI 具有降低死亡率的效應，推測可能透過調節免疫反應而緩和 ALI 病程進展，詳細機轉尚待進一步探討。
Acute lung injury (ALI) is often seen in critically ill patients that may be caused by direct gastric fluid reflux or bacterial pneumonia. Fish oil containing EPA (Eicosapentaenoic acid) and DHA (Docosahexaenoic Acid) has been reported to improve clinical and experimental inflammatory diseases outcomes, because of the anti-inflammatory properties. Klebsiella pneumonia (K. pneumonia) infection could result in pneumonia outside the hospitals, even use antibiotics therapy, still has 50% death rate. The purpose of this study was to investigate the effects of short-term fish oil supplementation on K. pneumoniae induced acute lung injury (ALI) in mice.Female BALB/c mice at 6-8 wk of age (n=86) were divided into two groups, including Milli-Q water group and Fish oil group. Mice were treated with Milli-Q water(150 μL /mouse/day) or Fish Oil(40 mg/mouse/day) by gavage once a day for 7 days. After the 7-day feeding period, mice were induced ALI by intratracheal administration with 50 ?l of 1 ×105 colony-forming units (CFU) KP957. Mice were killed at 4 time points including 4, 24, 48 and 72 hrs after ALI challenge. Cytokines, bacterial loads in the bronchoalveolar lavage fluid (BALF), histopathology of the lungs, and survival rates were examined.The survival ratesat the 6th day afterK. pneumoniae challenge were 50% and 0% in Fish oil and MQ water-treated mice, respectively. The inflammatory cytokines in serum and BALF were were no differences between two groups. The bacterial loads in the BALF were no significant differences between the MQ and the fish oil groups. We suggested that the benefical effect of fish oil supplementation probably had nothing to do with inhibiting the growth of K. pneumoniae. The histopathology of the lungs indicated that the severity of ALI tended to be decreased by fish oil supplementation. Therefore, our results showed that short-term fish oil supplementation had an ameliorative effect on the serverity and survival by direct K. pneumoniae challenge in mice. However, mechanisms underlying of fish oil remain unclear, it may be partly contributed the anti-immunomodulatory properties. |
