促進或抑制巨噬細胞株分泌前列腺素E2的食材對發炎反應的影響

Abstract

前列腺素 E2 (PGE2) 為 arachidonic acid (AA) 代謝物，涉及廣泛的生理活性，並參與發炎反應的發展。研究指出，多種天然食材對 RAW264.7 巨噬細胞分株泌 PGE2 的影響，符合其傳統屬性的分類，龍眼、荔枝、桂圓等熱性食材水萃取物可促進分泌 PGE2，反之，菊花、蓮子心、苦瓜等冷性食材，可抑制 LPS 刺激後的 PGE2 分泌，且富含抗氧化成份的洋蔥，亦可抑制 LPS 刺激後的 PGE2 分泌，推測這些食材可能具調節發炎介質分泌的作用，因此本研究以細胞培養及動物餵食模式探討不同屬性之食材對發炎反應之影響。 首先採用龍眼、荔枝、桂圓、蓮子心、菊花，和洋蔥水萃物培養 RAW264.7 巨噬細胞株，並分析其 PGE2 與 TNF-alpha 等發炎介質的分泌。結果顯示，龍眼、荔枝及桂圓等熱性食材可顯著活化巨噬細胞自發性分泌 PGE2 與 TNF-alpha，蓮子心及菊花等冷性食材與洋蔥不影響自發性 PGE2 與 TNF-alpha 分泌；以樣品預處理細胞，移除後以 LPS 刺激，龍眼、荔枝、桂圓、蓮子心、菊花和洋蔥水萃物均可顯著抑制 PGE2 生成。 進一步採用 BALB/c 腹腔抽出之巨噬細胞進行實驗，以桂圓、菊花及洋蔥進行處理，結果顯示，桂圓促進自發性 PGE2、TNF-alpha 及 IL-6 生成，並降低 LPS 刺激下 TNF-alpha、IL-6 與 IL-10 分泌；菊花不影響自發性 PGE2 及 TNF-alpha 生成，顯著降低 LPS 刺激下 PGE2 分泌，但促進 IL-6 分泌；在洋蔥水萃取物處理下，可顯著抑制 LPS 刺激後 PGE2 及 IL-6 分泌。細胞株與腹腔細胞之結果一致，熱性食材可促進 PGE2 及 TNF-alpha 分泌，但高劑量會抑制 TNF-alpha 的分泌，且對其他細胞激素無一致的影響，冷性食材可抑制 LPS 刺激下 PGE2 分泌，但不影響 TNF-alpha 生成，而桂圓、菊花和洋蔥皆促進 IL-6 分泌，促進程度菊花 > 桂圓 > 洋蔥，與冷熱屬性無關。 接著以桂圓、菊花及洋蔥三種樣品餵食 BALB/c 小鼠 4 週，結果顯示，桂圓餵食不影響腹腔細胞生成 PGE2，但菊花餵食促進腹腔細胞分泌PGE2，低劑量洋蔥餵食則促進 LPS 刺激下腹腔細胞分泌 PGE2 及 TNF-alpha，高劑量洋蔥餵食則可降低 BALB/c 鼠尿液中 bicyclo-PGE2 含量；T 細胞激素分泌量方面，桂圓餵食可顯著促進自發性 IL-2，且降低 IFN-gamma 和 IL-10 分泌，並顯著促進 ConA 刺激下 IL-2、IFN-gamma、IL-4 與 IL-5 分泌。洋蔥餵食顯著促進自發性 IL-2 且抑制 IFN-gamma 分泌，並顯著促進 ConA 刺激下 IFN-gamma 與 IL-5 分泌。菊花餵食可顯著降低 IFN-gamma，並增加 IL-5 和 IL-10 分泌，並促進 ConA 刺激下 IFN-gamma、IL-4 與 IL-5 的分泌。三種樣品對免疫反應之調節作用各有不同。 最後分別以桂圓、菊花與洋蔥等樣品餵食 BALB/c 鼠，再給予 15 mg/kgBW 之 LPS 注射致急性發炎。結果顯示，注射 LPS 後期血清中 TNF-alpha、IL-6 和小鼠存活時間有高相關性，餵食桂圓低劑量 (25 mg/day) 小鼠體內生成較高 IL-6 和 IFN-gamma。餵食菊花低劑量 (2.5 mg/day) 小鼠血清中 TNF-alpha、IL-6 均顯著較高。餵食洋蔥高劑量 (40 mg/day) 小鼠血清 IL-6 和 IFN-gamma 顯著較低，存活率有較高趨勢 (Hazard ratio: 0.48, P = 0.055)。由動物實驗之結果得知，熱性食材可促進脾臟細胞分泌 IL-2，冷性食材可抑制 IL-2 分泌，但對其他細胞激素分泌並無相同之效應，在免疫反應的調節上無一致的結果，因此推測，促進或抑制巨噬細胞分泌 PGE2 之冷熱食材，對於急性發炎動物並無顯著區分，但具有影響細胞激素調節之潛力。

Prostaglandin E2 (PGE2) is a principal mediator of inflammation in inflammatory diseases. Previous studies showed that water extracts of foods traditionally regarded as ‘heating’ (longan, lychee ,and dried longan) enhance basal PGE2 production, while those from ‘cooling’ foods (Chrysanthemum flower and lotus plumule) and foods possessing antioxidant properties such as onions, inhibit LPS-induced PGE2 production by macrophage cell line RAW264.7. However, whether these food samples could mediate in inflammation in vivo was unknown. In this study, RAW264.7 was treated with samples mentioned above and showed similar secreting profiles in PGE2 and TNF-alpha. Longan, lychee, and dried longan enhanced PGE2 and TNF-alpha productions spontaneously, while Chrysanthemum flower and lotus plumule did not. After samples were removed from the media, PGE2 production was inhibited in pretreated RAW264.7, regardless of whether ‘heating’ or ‘cooling’ samples were used in pretreatment. Subsequently, macrophages in peritoneal exudate cells (PECs) of BALB/c mice were treated with dried longan, Chrysanthemum flower, or onion. Results show that water extract of dried longan enhanced PGE2, TNF-alpha, and IL-6 spontaneously, and inhibited LPS-induced TNF-alpha and IL-6 when stimulated. Chrysanthemum flower inhibited LPS-induced PGE2 production but enhanced LPS-induced IL-6, while onion inhibited both LPS-induced PGE2 and IL-6. In order to determine the effects of samples on animals, samples were tube-fed to BALB/c mice daily for 4 weeks, and mice were sacrificed for analysis. It showed that feeding of dried longan did not affect PGE2 production of PECs ex vivo, while feeding of Chrysanthemum flower enhanced PEC PGE2 and TNF-alpha productions. Dried longan also significantly enhanced spontaneous IL-2 production, and ConA-induced IL-2, IFN-gamma, as well as IL-4 and IL-5 in splenocytes. Conversely, feeding of Chrysanthemum flower showed no effects on IL-2. Feeding onion water extract at the dosage of 10 mg/day enhanced LPS-induced PGE2 and TNF-alpha by PECs, and feeding at dosage of 20 mg/day significantly lowered urine bicyclo-PGE2 levels, which indicates a lowered PGE2 metabolites level. Finally, to investigate the effects of samples in inflammation in vivo, these samples were fed to BALB/c mice again for 1 week, then an acute systemic inflammatory response was induced by injecting LPS (15 mg/kgBW) into the peritoneal cavity. It showed that the pro-inflammatory cytokines TNF-alpha and IL-6 in serum were negatively correlated with mice survival. Feeding of dried longan (25 mg/day) and Chrysanthemum flower (2.5 mg/day) significantly enhanced IL-6 in serum, and mice in both groups did not survive after 72 h. Feeding of onion (40 mg/day) significantly lowered IL-6 in serum, and mice showed a 31.3% survival at 72 h after LPS administration. These in vivo results showed that the ‘heating’ and the ‘cooling’ foods affect differently in immune regulation, and are capable of mediating cytokine productions in vivo, although they fail to affect significantly on acute inflammation survival.