脂氧素在炎症中作用的研究进展

脂氧素（lipoxin,LX）是来源于花生四烯酸、经脂氧合酶催化合成的一类生物活性物质。在哺乳动物中,其主要包括脂氧素A4（LXA4）和脂氧素B4（LXB4）。研究表明,在炎症过程中,LX能够抑制白细胞向炎症部位的趋化并促进巨噬细胞吞噬局部凋亡的粒细胞及其他损伤细胞,从而抑制炎症的进程,促进炎症的消退。由于其在炎性疾病中所发挥的独特的抗炎和促进炎症消退的功能而被关注。本文主要介绍近年来LX在合成、代谢、生物学功能及疾病发生中作用的研究进展。     

LXA4、ALDH1及PLGF在子宫内膜异位症患者中的表达及意义

目的观察脂氧素A₄(LXA₄)、乙醛脱氢酶1(ALDH₁)和胎盘生长因子(placental growth factor, PLGF)在子宫内膜异位症(endometriosis, EMT)患者中的表达及意义。方法 选取2012年1月至2014年1月经病理诊断为EMT的患者165例为异位内膜组,选择同期健康妇女30例为健康对照组。根据r-AFS将EMT分为Ⅰ期45例、Ⅱ期48例,Ⅲ期37例和Ⅳ期35例,根据痛经评分标准分为: 0分53例,1分43例,2分37例和3分32例。观察异位内膜组和正常对照组的LXA₄、ALDH₁和PLGF水平变化及EMT患者的LXA₄、ALDH₁和PLGF水平与EMT分期和痛经评分的关系。结果 异位内膜组的LXA₄水平明显低于正常对照组(P<0.01),ALDH₁和PLGF水平明显高于正常对照组(P<0.01)。随着EMT分期的升高和痛经评分的增加,LXA₄水平明显降低(P<0.01),而ALDH₁和PLGF水平明显升高(P<0.01)。结论LXA₄、ALDH₁和PLGF的异常表达与EMT的发生发展具有重要联系,联合检测对EMT的早期诊断具有重要意义。     

脂氧素对巨噬细胞RAW264.7的抗炎实验研究

目的 研究脂氧素(LX) A4和叔丁氧羟基-苯丙氨酸-亮氨酸-苯丙氨酸-亮氨酸-苯丙氨酸(BOC-2)对LPS作用巨噬细胞RAW264.7存活的影响.方法 取对数生长期的巨噬细胞RAW264.7为研究载体,实验用不同浓度的脂多糖(LPS)在不同时间点处理细胞,观察LX A4和BOC-2对LPS作用巨噬细胞RAW264.7后的存活率.CCK-8法观察LPS对各组巨噬细胞RAW264.7的不良反应,Western blot法检测LX A4和BOC-2对LPS处理后巨噬细胞RAW264.7的Toll样受体4(TLR4)和pNF-κB p65蛋白水平,酶联免疫吸附(ELISA)法检测LX A4和BOC-2对LPS处理后巨噬细胞RAW264.7培养上清液中白细胞介素6(IL-6)水平.结果 在1 000 ng/mL浓度LPS组,作用时间6h,巨噬细胞RAW264.7内TLR4蛋白水平和pNF-κB p65蛋白水平显著高于其余各组(P＜0.05).在LPS作用下,LX A4组细胞存活率显著高于对照组(P＜0.05);BOC-2组在LPS作用后巨噬细胞RAW264.7的存活率显著低于无LPS作用(P＜0.05).在LPS作用下,LX A4组pNF-κB p65蛋白水平低于对照组及BOC-2组(P＜0.05),BOC-2组pNF-κB p65蛋白水平高于其余各组(P＜0.05).在LPS作用下,LX A4组IL-6的水平低于对照组及BOC-2组(P＜0.05).结论 LX A4能够抑制LPS对巨噬细胞RAW264.7的作用及TLR4/NF-κB信号通路的激活,有助减轻炎性反应.     

脂氧素 A4的抗结肠纤维化作用及其机制

目的：观察脂氧素A4（LX A4）的抗结肠纤维化作用,并探讨其机制。方法将32只BALB／C雄性小鼠随机分为4组,每组8只。对照组不造模,仅给予生理盐水灌肠;模型组、CS组、CS／LX A4组建立结肠炎结肠纤维化模型后,分别给予生理盐水、壳聚糖纳米粒、壳聚糖／LX A4纳米粒灌肠。10 d后取结肠组织检测疾病活动指数（DAI）,HE染色法光镜下观察结肠组织组织学损伤指数（HI）,免疫组化法检测结肠组织转化生长因子－β1（ TGF－β1）和Smad3蛋白表达量。结果实验第10天,与对照组比较,其余3组大鼠DAI显著升高（ P＜0．01）;CS／LX A4组大鼠DAI低于模型组,但差异无统计学意义（ P＞0．05）。无论是结肠炎症程度、病变深度,还是隐窝破坏,其余3组结肠组织HI均显著高于对照组（P＜0．05,P＜0．01）,CS／LX A4组均显著低于模型组和CS组（P＜0．05,P＜0．01）。模型组结肠组织TGF－β1、Smad3表达量均较对照组显著升高（P＜0．01）;与模型组比较, CS／LX A4组和CS组结肠组织TGF－β1、Smad3表达量均明显降低（ P＜0．05）,但均显著高于对照组（ P＜0．05）。结论 LX A4可以通过下调TGF－β1和Smad3的表达,减轻炎症反应,进而遏制结肠纤维化的进展。     

Lipoxin A4 selectively programs the profile of M2 tumor‐associated macrophages which favour control of tumor progression

In tumor microenvironments, the macrophage population is heterogeneous, but some macrophages can acquire tumor‐promoting characteristics. These tumor‐associated macrophages (TAM) exhibit an M2‐like profile, with deficient production of NO and ROS, characteristics of pro‐inflammatory M1 cytotoxic macrophages. Lipoxins (LX) and 15‐epi‐lipoxins are lipid mediators which can induce certain features of M2 macrophages in mononuclear cells, but their effects on TAM remain to be elucidated. This study tested the hypothesis that ATL‐1, a synthetic analogue of 15‐epi‐lipoxin A₄, could modulate TAM activity profile. We show that human macrophages (MΦ) differentiated into TAM‐like cells after incubation with conditioned medium from MV3, a human melanoma lineage cell. Contrasting with the effects observed in other M2 subsets and M1 profile macrophages, ATL‐1 selectively decreased M2 surface markers in TAM, suggesting unique behavior of this particular M2 subset. Importantly, these results were replicated by the natural lipoxins LXA₄ and the aspirin induced 15‐epi‐LXA₄ (ATL). In parallel, ATL‐1 stimulated TAM to produce NO by increasing the iNOS/arginase ratio and activated NADPH oxidase, triggering ROS production. These alterations in TAM profile induced by ATL‐1 led to loss of the anti‐apoptotic effects of TAM on melanoma cells and increased their cytotoxic properties. Finally, ATL‐1 was found to inhibit tumor progression in a murine model in vivo, which was accompanied by alterations in TAM profile and diminished angiogenesis. Together, the results show an unexpected effect of lipoxin, which induces in TAM a change from an M2‐ to an M1‐like profile, thereby triggering tumor cell apoptosis and down‐modulating the tumor progression.     

Aspirin-triggered lipoxin induces CB1-dependent catalepsy in mice

Evidence are that inhibition of cyclooxygenase 2 (COX-2) enhances endocannabinoid signaling, indicating a crosstalk between these two eicosanoid pathways. Aspirin, a non-selective COX inhibitor, acetylates COX-2 with generation of a lipoxygenase (LOX) substrate, whose end product is the 15-epi-lipoxin A₄ (15-epi-LXA₄), an aspirin-triggered lipoxin. Our objective was to investigate whether 15-epi-LXA₄ would potentiate in vivo effects of the endocannabinoid anandamide (AEA). Catalepsy was selected as a behavioral parameter and tested 5 min after AEA injection in all experiments. AEA induced dose-dependent (200 pmol/2 μl, i.c.v.) catalepsy. A sub-dose of AEA (10 pmol/2 μl, i.c.v.) was potentiated by aspirin (300 mg/kg, p.o.) via a 5-LOX-dependent step. The cataleptic effect induced by the interaction between sub-doses of 15-epi-LXA₄ (0.01 pmol/2 μl, i.c.v.) and AEA (10 pmol/2 μl, i.c.v.) was prevented by the cannabinoid CB₁ receptors antagonist SR141716A (1 mg/kg, i.p.), but not by the antagonist of lipoxin ALX receptors Boc-2 (10 μg/kg, i.p.). While previous studies have shown that COX inhibition itself may enhance endocannabinoid effects, here we add another piece of evidence revealing that a LOX-derivative produced in consequence of COX-2 acetylation participates in this process.     

Cyclooxygenases and 5-lipoxygenase in Alzheimer's disease

Typically, cyclooxygenases (COXs) and 5-lipoxygenase (5-LOX), enzymes that generate biologically active lipid molecules termed eicosanoids, are considered inflammatory. Hence, their putative role in Alzheimer's disease (AD) has been explored in the framework of possible inflammatory mechanisms of AD pathobiology. More recent data indicate that these enzymes and the biologically active lipid molecules they generate could influence the functioning of the central nervous system and the pathobiology of neurodegenerative disorders such as AD via mechanisms different from classical inflammation. These mechanisms include the cell-specific localization of COXs and 5-LOX in the brain, the type of lipid molecules generated by the activity of these enzymes, the type and the localization of receptors selective for a type of lipid molecule, and the putative interactions of the COXs and 5-LOX pathways with intracellular components relevant for AD such as the gamma-secretase complex. Considering the importance of these multiple and not necessarily inflammatory mechanisms may help us delineate the exact nature of the involvement of the brain COXs and 5-LOX in AD and would reinvigorate the search for novel targets for AD therapy.     

LXA4诱导HO-1高表达对心肌细胞缺氧/复氧损伤的保护作用

目的:探讨脂氧素A4(lipoxinA4,LXA4)在大鼠心肌细胞缺氧/复氧损伤中的保护作用及可能机制?方法:将细胞随机分为5组,每组6孔,分别为对照组(con组)?缺氧/复氧组(H/R组)?LXA4预处理的缺氧/复氧组(LXA4 + H/R组)?HO-1抑制剂锌原卟啉(ZnPP)预处理的缺氧/复氧组(ZnPP + H/R组)?LXA4 + ZnPP预处理的缺氧/复氧组(LXA4 + ZnPP + H/R组)?观察细胞形态改变,测定细胞上清液中乳酸脱氢酶(lactate dehydrogenase,LDH)?肌酸激酶(creatine kinase,CK)水平以反映细胞损伤,并检测心肌细胞HO-1活性和HO-1的mRNA表达水平? 结果:与H/R组比较,LXA4 + H/R组细胞形态较规整,LDH?CK水平较低,而HO-1的活性及mRNA表达水平明显增加;LXA4 + ZnPP + H/R组终止了LXA4对缺氧/复氧细胞的保护作用,细胞形态明显改变,细胞死亡较多,HO-1的活性及mRNA水平受到抑制?结论:LXA4预处理可诱导大鼠心肌细胞HO-1高表达,具有抗心肌细胞缺氧/复氧损伤的保护作用?