Bromelain is a mixture of proteolytic enzymes derived from pineapple (Ananas comosus) fruit and stem possessing several beneficial properties, particularly anti-inflammatory activity. However, the molecular mechanisms underlying the anti-inflammatory effects of bromelain are unclear. This study investigated the anti-inflammatory effects and inhibitory molecular mechanisms of crude and purified rhizome bromelains on lipopolysaccharide (LPS)-induced inflammation in RAW 264.7 macrophage cells. RAW264.7 cells were pre-treated with various concentrations of crude bromelain (CB) or purified bromelain (PB), and then treated with LPS. The production levels of pro-inflammatory cytokines and mediators, including nitric oxide (NO), interleukin (IL)-6, and tumor necrosis factor (TNF)-α were determined by Griess and ELISA assays. The expressions of inducible nitric oxide synthetase (iNOS), cyclooxygenase (COX)-2, nuclear factor kappa B (NF-κB), and mitogen-activated protein kinases (MAPKs)-signaling pathway-related proteins were examined by western blot analysis. The pre-treatment of bromelain dose-dependently reduced LPS-induced pro-inflammatory cytokines and mediators, which correlated with downregulation of iNOS and COX-2 expressions. The inhibitory potency of PB was stronger than that of CB. PB also suppressed phosphorylated NF-κB (p65), nuclear factor of kappa light polypeptide gene enhancer in B-cells inhibitor alpha, extracellular signal-regulated kinases, c-Jun amino-terminal kinases, and p38 proteins in LPS-treated cells. PB then exhibited potent anti-inflammatory effects on LPS-induced inflammatory responses in RAW264.7 cells by inhibiting the NF-κB and MAPKs-signaling pathways.

中文翻译：

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菠萝根茎菠萝蛋白酶通过下调脂多糖 (LPS) 刺激的 RAW264.7 细胞中 NF-κB 和 MAPK 信号通路的抗炎作用。


菠萝蛋白酶是从菠萝 ( Ananas comosus ) 果实和茎中提取的蛋白水解酶混合物，具有多种有益特性，尤其是抗炎活性。然而，菠萝蛋白酶抗炎作用的分子机制尚不清楚。本研究探讨了粗制和纯化的根茎菠萝蛋白酶对脂多糖 (LPS) 诱导的 RAW 264.7 巨噬细胞炎症的抗炎作用和抑制分子机制。 RAW264.7细胞用不同浓度的粗制菠萝蛋白酶（CB）或纯化菠萝蛋白酶（PB）预处理，然后用LPS处理。通过 Griess 和 ELISA 测定测定促炎细胞因子和介质的产生水平，包括一氧化氮 (NO)、白细胞介素 (IL)-6 和肿瘤坏死因子 (TNF)-α。通过蛋白质印迹分析检测诱导型一氧化氮合成酶 (iNOS)、环氧合酶 (COX)-2、核因子 kappa B (NF-κB) 和丝裂原激活蛋白激酶 (MAPK) 信号通路相关蛋白的表达。菠萝蛋白酶的预处理剂量依赖性地减少 LPS 诱导的促炎细胞因子和介质，这与 iN​​OS 和 COX-2 表达的下调相关。 PB的抑制作用强于CB。 PB 还抑制磷酸化 NF-κB (p65)、B 细胞抑制剂 α 中的 kappa 轻多肽基因增强子核因子、细胞外信号调节激酶、c-Jun 氨基末端激酶和 LPS 处理的细胞中的 p38 蛋白。然后，PB 通过抑制 NF-κB 和 MAPK 信号通路，对 RAW264.7 细胞中 LPS 诱导的炎症反应表现出有效的抗炎作用。