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摘要: 一氧化碳(carbon monoxide,CO)是一种由哺乳动物体内血红素氧化酶(heme oxygenase,HO)催化血红素降解产生的重要内源性气体信号传导分子。CO参与了生物体内多种生理活动和病理过程,并与器官组织中的细胞保护和稳态维持密切有关。越来越多的研究表明,CO能够通过多种作用机制,在痛觉的发生、发展过程中发挥调节干预作用,但其作用机制尚未完全明确,且给药方式的不可控因素也使其应用受到较大限制。本文旨在梳理CO在疼痛调控中可能的靶点和途径,并对CO临床应用中所面临的挑战和机遇进行讨论,为CO镇痛药物的进一步研发提供线索。Abstract: Carbon monoxide (CO) is an endogenous gasotransmitter produced by the degradation of heme in the presence of heme oxygenase (HO) in mammals. It has been demonstrated that CO participates in a variety of physiological activities and pathological processes, and is closely related to cell protection and homeostasis maintenance in organ tissues. It has been shown by a growing number of studies that CO may play a regulatory and interventional role in the process of the occurrence and development of pain through a variety of mechanisms of action. However, its mechanism of action is still not fully understood and the uncontrollable factors concerning CO administration also placed considerable limitation to its application. This paper reviews the potential targets and pathways of CO in pain regulation and discusses the challenges and opportunities in the clinical application of CO in order to provide suggestions for further exploration and development of CO analgesics.
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Keywords:
- Carbon monoxide /
- Gasotransmitter /
- Pain and analgesia /
- Nociception
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疼痛是人体对外界刺激或内在机体的损伤产生的一种复杂的应激反应,是人类最常见的痛苦之一。疼痛不仅对循环、呼吸、内分泌等多个系统造成不良应激反应,同时也会导致焦躁、抑郁等心理应激。据统计,全球疼痛的发病率已达到35%~45%[1],但其病因复杂、机制不清,不仅严重影响患者的身体机能和生活质量,也给家庭和社会带来极大的负担[2]。一氧化碳(carbon monoxide,CO)是一种无色无味的气体,曾一度被视为有毒气体。随着气体信号分子研究的逐步开展,被发现直接或间接参与了人体多种生理、病理活动的调节,并与一氧化氮(nitric oxide,NO)和硫化氢(hydrogen sulfide,H2S)被认为是主要的内源性气体分子递质,在心血管、中枢神经和胃肠道系统中起着重要作用。近年来,多项研究表明CO在疼痛调节方面也起到重要的作用,可能通过调控多种靶点参与对疼痛的调节。虽然,CO参与疼痛治疗和调控的分子机制尚未得到充分阐释,但已强烈提示CO具有成为新一代镇痛药物分子的巨大潜力。本文拟对近年来CO在疼痛调节中的机制进行综述。
1. CO的生理特性
CO是一种具有重要作用的内源性信号传导分子,由哺乳动物体内血红素氧化酶(heme oxygenase,HO)催化血红素降解产生,同时产生二价铁离子和胆绿素(biliverdin,BV),铁离子通过螯合作用被储存进铁蛋白,胆绿素则被胆绿素还原酶催化形成胆红素[3]。HO及其产物CO在细胞的氧化还原状态中起关键作用,与体内多种器官组织中的细胞保护和稳态维持有关,可通过抑制氧化应激等反应调节维持细胞的完整性和组织内的稳态,产生强大的抗炎和抗伤害性感受作用[4]。
近年来,CO的多种生物学活性也被逐渐发现:在心脑血管疾病、神经系统疾病、肝肾损伤、炎症疾病、器官移植等多种动物模型中CO均表现出良好的治疗作用。CO在脑缺氧缺血性损伤模型中表现出明显的神经保护作用;通过抑制髓鞘反应性免疫细胞活化,CO能够减少自身免疫性神经炎症损伤;CO通过减少线粒体膜通透性的异常变化抑制星形胶质细胞凋亡[5-7]。
2. CO的疼痛调控机制
CO在疼痛干预方面展现出其独特的优势,无论是内源性CO还是外源性CO,都在多种类型的疼痛动物模型中参与了伤害性感受信号传导的调控。虽然其镇痛作用机制尚未被完全阐明,但研究发现,在CO对伤害性疼痛的干预中,环磷酸鸟苷(cyclic guanosine monophosphate,cGMP)、cGMP/ATP-敏感性钾通道、NO、核因子E2相关因子2(nuclear factor erythroid-2 related factor,Nrf2)等发挥了重要作用[8],而CO对神经病理性疼痛的治疗效果则可能与Cav3.2型钙通道、P2X2受体(P2X2 receptor,P2X2R)等作用靶点密切有关[9-10]。CO还被发现能够与阿片类药物、大麻素等联合使用发挥协同镇痛作用。而CO的抗炎作用将减少炎症因子的释放,有助于疼痛的控制;CO的细胞保护和神经保护等作用也被认为能够有效改善疼痛症状。CO作为一种独特的内源性气体信号分子,将有可能从炎症控制、神经保护、通道调控等多方面整体发挥对疼痛的治疗和干预作用[5-7]。
离子通道在原发性疼痛和继发性疼痛的发生发展中发挥着关键作用[11],被认为是调节和抑制疼痛的主要治疗靶点。而CO通过多种机制作用于各类离子通道,对离子通道进行调控作用,发挥镇痛作用。由图1可见,在CO对伤害性疼痛的干预中,电压门控性钾离子通道2.1(voltage-gated potassium channels 2.1,Kv2.1)、L型Ca2+通道、双孔钾通道〔TWIK-related potassium(K+)channel-1,TREK-1〕、cGMP、连接蛋白(connexin,Cxs)等发挥了重要作用。CO的抗炎机制还包括激活过氧化物酶体增殖剂激活受体(peroxisome proliferators-activated receptors,PPARs)、丝裂原活化蛋白激酶(mitogen-activated protein kinase,MAPK)和Nrf2[12]等。值得注意的是,CO的作用机制复杂,往往在不同细胞不同状态发挥不同的效应。虽然已有较多研究显示了CO对于疼痛反应的调控作用,但具体的机制尚未完全阐明。
图 1 CO与疼痛调节机制Figure 1. CO and its pain regulation mechanismsKv2.1: Voltage-gated potassium channels 2.1; TREK-1: TWIK-related potassium (K+) channel-1; ROS: Reactive oxygen species; sGC: Soluble guanylyl cyclase; cGMP: Cyclic guanosine monophosphate; HO: Heme oxygenase; CO: Carbon monoxide; H2S: Hydrogen sulfide; NO: Nitric oxide; BV: Biliverdin; CO-RM: Carbon monoxide releasing molecules; L-Ca2+: L-type calcium channel; P2X: Purniergic 2X; BKca: Large conductance calcium activated potassium channels; NADPH: Reduced form of nicotinamide-adenine dinucleotide phosphate; NADP+: Oxidized form of nicotinamide-adenine dinucleotide phosphate.2.1 离子通道
2.1.1 Kv2.1
钾离子平衡在维持细胞体积方面起着至关重要的作用。Kv2.1是哺乳动物中枢神经元中主要表达的延迟整流器,被证明参与了神经细胞的氧化凋亡过程,其被激活后释放出大量钾离子,促进了细胞的凋亡。研究表明,使用CO供体对海马神经元进行处理,可以有效避免海马神经元因K+电流导致的凋亡。AL-OWAIS等[13]也获得类似的结果,CO供体可以通过抑制Kv2.1离子通道,进而保护细胞免受氧化环境诱导的凋亡。
在使用抗氧化剂对细胞进行处理的情况下,CO对Kv2.1的抑制作用会显著减弱,这可能与CO抑制L型Ca2+通道进而产生活性氧(reactive oxygen species,ROS)有关[14]。相关研究表明,CO能够与线粒体电子传递链上的细胞色素C结合产生电子泄露,生成更多ROS[15],ROS可发挥直接抑制Kv2.1的作用,也可以调节NADPH氧化酶的活性影响CO的内源性生成。此外,MAPK信号通路参与电压门离子通道的调控[16],而CO可以降低小鼠特定脑区升高的MAPK含量,调节Kv2.1,发挥神经保护的作用[17]。总之,CO能够通过多种途径调节Kv2.1的状态,但具体分子机制还有待进一步研究。
2.1.2 L型Ca2+通道
L型Ca2+通道在疼痛调节方面发挥着重要作用。研究表明L型Ca2+通道被抑制后,脊髓后角神经元细胞的兴奋性突触后电流频率会随之降低[18],在降低小鼠对有害机械刺激反应的同时[19],也可以抑制神经病理性疼痛[20]。CO可抑制L型Ca2+通道[21],提示CO抑制Ca2+通道引发下游作用可能对疼痛反应进行调节从而进一步发挥镇痛作用。
2.1.3 TREK-1
双孔域K+2P通道家族在中枢神经系统广泛分布,参与神经元的兴奋性[22]。研究发现,双孔域K+2P通道家族中的TREK-1通道基因的缺乏或是对通道的抑制都会发生显著痛觉敏化,而激活TREK-1通道则有明显的疼痛抑制作用,提示TREK-1离子通道在镇痛方面可能发挥重要作用[23]。应用转染TREK-1离子通道的HEK293细胞进行研究,可观察到TREK-1通道能被CO供体激活而产生激活电流,提示CO能有效激活TREK-1通道[24]。虽然CO激活TREK-1通道的分子机制还需进一步研究,但可以明确的是,TREK-1通道可能是CO发挥镇痛作用的相关靶点。
2.1.4 其他离子通道
电压和钙激活的钾通道(BKCa通道)由slo1基因编码,由4个亚基组成。它在各类动物生命活动中都发挥作用,并且参与了人体神经元动作电位的产生和神经递质的释放。研究表示,外源性或内源性的CO都能有效激活BKCa通道,并且随CO浓度的增加,BKCa通道引导的电流越大[25]。此外,P2X受体是一种ATP依赖的配体离子通道[26],在多种哺乳动物体内表达,在神经通路中发挥作用。CO可以激活P2X7亚型发挥神经胶质细胞保护作用[27]。
越来越多的研究证明,CO参与了生物体内多种离子通道的调控,虽然有关CO直接作用于离子通道进而发挥镇痛作用的证据较少,但通过CO对离子通道的直接或间接调控的研究,能够帮助进一步了解了CO的神经细胞保护以及镇痛活性,并为CO的新药开发提供了有价值的药物靶点。
2.2 HO/CO/cGMP
cGMP是一类具有细胞内信息传递作用的第二信使,通常参与细胞膜离子通道的开启、糖原分解、细胞凋亡以及平滑肌舒张运动[28]。HO/CO/cGMP通路作为最常被研究的CO通路,迄今已发现该通路在多种疼痛中发挥重要作用,HO-1亚型的过表达可发挥强抗炎症和抗伤害感受作用,而HO-2亚型的过表达会增强伤害性感受[29],其机制根据cGMP下游的cGMP依赖蛋白(cGMP-dependent protein kinases,cGK)、离子通道、受体的类型差别而有所不同。
STEINER等[30]发现,由HO-1催化产生的内源性CO能够在受到机械伤害的小鼠模型中发挥抗痛觉过敏作用,这可能与初级传入神经细胞中cGMP水平升高有关。NASCIMENTO等[31]发现,经诱导HO/CO途径的福尔马林疼痛模型大鼠与对照组相比,对伤害刺激的退缩反应明显减少。LIANG等[32]发现,HO-2缺失型小鼠经后爪注射福尔马林后发生长期异常疼痛的数量较野生型小鼠更少。在另一项实验中[33],注射福尔马林后的野生型小鼠与HO-2缺失型小鼠相比,脊髓中钙离子/钙调素依赖性蛋白激酶Ⅱ(Ca2+/calmodulin-dependent protein kinase Ⅱ,CaMKⅡ)α亚基的mRNA及蛋白水平呈时间依赖性增加。CaMKⅡ基于对吗啡镇痛的耐药效应参与神经突触的可塑性变化,是突触传递的长时程增强(long-term potentiation,LTP)的关键组成部分。这些研究表明,HO/CO/cGMP可能是通过调节CaMKⅡ表达,影响疼痛感受。
细胞内cGMP水平的变化可以导致伤害感受的增强或减弱,这取决于cGMP增加的幅度以及用药部位(外周神经系统或脊髓)。研究表明[34],脊髓中增加的cGMP会抑制脊髓神经元的活性,主要影响背部和脊髓的伤害性神经元。另一方面[35],位于脊髓背角的神经细胞受到脊髓中cGMP水平升高的影响导致兴奋性增加。因此脊髓cGMP的增高对疼痛可能有双重效果,高幅度的cGMP增加可能加深伤害性感受,而低幅度变化可起到镇痛作用。
2.3 HO/CO/Cxs
Cxs是一组具有相同质膜拓扑结构的蛋白质。近年来,CO已被认为是一种新型的连接蛋白半通道调控分子,可有效调控HeLa和MCF-7细胞中的Cx43和Cx46[36]。研究表明,脊髓损伤和神经刺激可上调Cx43的表达[37],且Cx43的持续上升可能与晚期神经性疼痛的维持有关[38]。l-THP是一种四氢原小檗碱异喹啉生物碱,已被证实对化疗诱导的神经性疼痛模型小鼠具有强效的镇痛作用[39]。l-THP的衍生物左旋延胡索明l-CDL在最近的一项研究中[40]被首次证明通过Nrf2/HO-1/CO通路抑制脊髓星形胶质细胞中Cx43的产生,从而抑制由长春新碱导致的神经性疼痛。
2.4 抑制炎症反应
炎症反应往往是疼痛发生的前驱现象,研究表明HO-1的表达上调升高内源性CO水平,使得炎症细胞迁移减缓[41]、炎性物质分泌下调,提示CO水平升高可能是机体在炎性反应下的一种主动保护作用。HO-1抑制剂的使用能够明显增加炎性部位嗜中性粒细胞的迁移,而CO供体或者HO-1激活剂则可以有效抑制炎性部位嗜中性粒细胞的迁移[42]。细胞水平上,一氧化碳释放分子〔tricarbonyldichlororuthenium (Ⅱ) dimer,CORM-2〕可以有效抑制细胞因子刺激所导致的一氧化氮合酶2(nitric oxide synthase 2,NOS-2)的mRNA表达增加和亚硝酸盐的产生,并且通过抑制白细胞介素(interleukin,IL)-6抑制基质金属蛋白酶7(matrix metalloproteinase-7,MMP-7)基因的转录[43]。在动物水平上,CORM-2还能显著减少坐骨神经缩窄性损伤引起的痛觉过敏,同时抑制小胶质细胞和星形胶质细胞的活化,表现出明显的抗炎作用[9]。在脑出血的动物模型中,使用CO供体CORM-3对动物进行预处理,可抑制脑损伤、降低炎症因子水平,发挥中枢神经保护作用[44]。
2.4.1 抑制小胶质细胞的活化
胶质细胞的激活在中枢神经系统疼痛的发生发展中,发挥着重要作用[45],而抑制胶质细胞的活化可以降低中枢对疼痛的敏感度。神经刺激性激活能够通过激活核因子κB(nuclear factor kappa-B,NF-κB)途径,诱导小胶质细胞活化,导致神经突触的破坏[46]。在放射性脑损伤小鼠模型实验中,CO供体CORM-3可以增加细胞间黏附分子-1(intercellular cell adhesion molecule-1,ICAM-1)和诱导型一氧化氮合酶(inducible nitric oxide synthase,iNOS)的表达,显著改善小鼠的学习和记忆能力[47]。HO-1表达上调能够保护大鼠星形胶质细胞,减少IL-1导致的炎症反应[48]。此外,CO可防止脂多糖(lipopolysaccharide,LPS)引起的小胶质细胞呼吸抑制和ATP水平降低,同时降低炎症因子含量[49]。同样,CO对脑缺血小鼠模型具有抑制小胶质细胞的活化、减少肿瘤坏死因子(tumor necrosis factor-α,TNF-α)的产生、减少脑损伤的作用[50]。如前所述,CO对于小胶质细胞抑制作用可能是通过下调NF-κB机制所产生的,故此CO所产生的作用具有一定的广泛性。
2.4.2 抑制巨噬细胞的活化
巨噬细胞是单核噬细胞系统的组成部分[51]。激活的巨噬细胞会表达大量细胞因子并向趋化因子迁移。缺乏HO-1的巨噬细胞在活化状态会表达更多的IL-1B、IL-18,而如果对HO-1进行过表达,巨噬细胞释放IL-1B、核苷酸结合寡聚结构域样受体蛋白3(NOD like receptor protein 3,NLRP3)和IL-18的能力就会被抑制,提示CO对于巨噬细胞的活化有抑制作用[52]。LEAKE等[53]的研究也发现了CO对巨噬细胞的抑制效果,但也发现CO对巨噬细胞的作用存在体内外的差异,在体内作用时间更长、更不容易被炎性物质所抵消。在巨噬细胞的体外实验中,发现CORM-3调节体外巨噬细胞M1和M2表型,在M1巨噬细胞中持续抑制iNOS表达,在M2巨噬细胞中对CD206和Ym-1蛋白进行快速上调[54],另一巨噬细胞的体外实验则发现CORM-2和CORM-3释放的CO可明显抑制巨噬细胞中LPS引起的炎症反应,减少TNF的释放以及降低亚硝酸盐水平[55]。
2.4.3 抑制炎性细胞因子的表达
炎性细胞因子有TNF、IL等,在细胞坏死或免疫细胞活化时被大量释放,进一步激活免疫系统以及诱导周围组织的炎症反应。免疫系统激活会促进神经疼痛[56],并且在慢性神经痛患者的血液、脑脊液中可发现炎症细胞因子的上升[57]。使用炎症细胞因子抑制剂可以降低细胞因子水平并缓解疼痛[58],而CO正好具有抑制炎性细胞因子的作用。在使用一氧化氮合酶(nitric oxide synthase,NOS)抑制剂的情况下,HO-1激活剂可以减轻免疫复合物的沉积诱发的水肿、嗜中性粒细胞增多,同时还可以减少TNF-α、IL-6两种炎性细胞因子的含量,从而使疼痛得以缓解[59]。
3. 小结与展望
CO作为一种重要的气体信号分子,可以从离子通道调控、免疫活化抑制、炎症控制、神经保护等多个机制实现对疼痛的治疗和干预。但其中仍有许多问题亟待发现与探索。一方面,CO-cGMP通路在不同类型疼痛中的作用已经明确,但其下游靶点的识别尚不清楚。可能涉及的通道包括但不限于:氨酰敏感通道、Nav1.5通道、Cav3.2 t型Ca2+通道、由线粒体产生的自由基介导的L型Ca2+通道抑制作用。另一方面,HO系统是探索CO与疼痛的关系中不容忽视的一环,HO-1亚型的过表达与急性和慢性疼痛期间的强抗炎症和抗伤害性感受作用相关,而HO-2亚型的过表达会产生伤害性感受作用。提示HO-1和HO-2这两种亚型在产生CO方面的差异以及它们与其他多种因素在伤害感受中相互作用的机制是很有潜力的研究方向,有必要全面了解HO/CO在痛觉中的潜在机制。
由于CO众所周知的毒性、无色无味的理化性质以及气体的难控制性,导致吸入给药方式具有较高的安全风险和不可控因素,如剂量控制差、靶向输送难、肺功能个体差异大等,使得CO气体的基础研究与临床转化都异常困难。现有的CO释放分子主要基于过渡金属络合物的结构,由于重金属潜在的安全性隐患使得其应用受到较大限制。因此,缺乏必要的研究工具探索CO作用机制,缺乏合适的药物分子挖掘CO治疗潜力,成为了相关研究领域的一大瓶颈。如何获得安全递送、可控释放的CO释放分子,开发类似“硝酸甘油”的有机CO前药成为了突破CO研究瓶颈的关键[60]。2016年,本团队与佐治亚州立大学的王炳和教授合作[6]利用分子内狄尔斯-阿尔德反应(Diels-Alder reaction),成功开发了全世界第一个CO有机小分子前药。该前药在接近生理条件下能够可控释放CO,为进一步开展CO在包括疼痛治疗在内的临床应用奠定了坚实的基础。
CO进行疼痛治疗有着独特的优势,且已经在诸多模型中获得良好的结果,但目前镇痛作用机制研究仍未明确,还需进一步探究其镇痛作用机制。此外,与吸入气体CO相同,CO释放分子也需要从代谢和毒理学的角度对其进行严格把控,以获得一个有效性与安全性平衡的治疗窗和用药策略。相信随着对CO镇痛机制研究的深入,CO更多的应用价值会逐渐浮现,为提供临床疾病治疗新的策略,给患者带来新的希望。
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利益冲突 所有作者均声明不存在利益冲突
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图 1 CO与疼痛调节机制
Figure 1. CO and its pain regulation mechanisms
Kv2.1: Voltage-gated potassium channels 2.1; TREK-1: TWIK-related potassium (K+) channel-1; ROS: Reactive oxygen species; sGC: Soluble guanylyl cyclase; cGMP: Cyclic guanosine monophosphate; HO: Heme oxygenase; CO: Carbon monoxide; H2S: Hydrogen sulfide; NO: Nitric oxide; BV: Biliverdin; CO-RM: Carbon monoxide releasing molecules; L-Ca2+: L-type calcium channel; P2X: Purniergic 2X; BKca: Large conductance calcium activated potassium channels; NADPH: Reduced form of nicotinamide-adenine dinucleotide phosphate; NADP+: Oxidized form of nicotinamide-adenine dinucleotide phosphate.
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[1] DAHLHAMER J, LUCAS J, ZELAYA C, et al. Prevalence of chronic pain and high-impact chronic pain among adults-United States, 2016. MMWR Morb Mortal Wkly Rep,2018,67(36): 1001–1006. DOI: 10.15585/mmwr.mm6736a2
[2] GASKIN D, RICHARD P. The economic costs of pain in the United States. J Pain,2012,13(8): 715–724. DOI: 10.1016/j.jpain.2012.03.009
[3] TENHUNEN R, MARVER H, SCHMID R. The enzymatic catabolism of hemoglobin: stimulation of microsomal heme oxygenase by hemin. J Lab Clin Med,1970,75(3): 410–421.
[4] LARSEN R, GOZZELINO R, JENEY V, et al. A central role for free heme in the pathogenesis of severe sepsis. Sci Transl Med,2010,2(51): 51ra71. DOI: 10.1126/scitranslmed.3001118
[5] CHOI Y K, MAKI T, MANDEVILLE E T, et al. Dual effects of carbon monoxide on pericytes and neurogenesis in traumatic brain injury. Nat Med,2016,22(11): 1335–1341. DOI: 10.1038/nm.4188
[6] JI X, ZHOU C, JI K, et al. Click and release: a chemical strategy toward developing gasotransmitter prodrugs by using an intramolecular Diels-Alder reaction. Angew Chem Int Ed Engl,2016,55(51): 15846–15851. DOI: 10.1002/anie.201608732
[7] CORREA-COSTA M, GALLO D, CSIZMADIA E, et al. Carbon monoxide protects the kidney through the central circadian clock and CD39. Proc Natl Acad Sci U S A,2018,115(10): E2302–E2310. DOI: 10.1073/pnas.1716747115
[8] CASTANY S, CARCOLÉ M, LEÁNEZ S, et al. The role of carbon monoxide on the anti-nociceptive effects and expression of cannabinoid 2 receptors during painful diabetic neuropathy in mice. Psychopharmacology (Berl),2016,233(11): 2209–2219. DOI: 10.1007/s00213-016-4271-4
[9] JURGA A, PIOTROWSKA A, STARNOWSKA J, et al. Treatment with a carbon monoxide-releasing molecule (CORM-2) inhibits neuropathic pain and enhances opioid effectiveness in rats. Pharmacol Rep,2016,68(1): 206–213. DOI: 10.1016/j.pharep.2015.08.016
[10] WANG H, SUN X. Carbon monoxide-releasing molecule-2 inhibits connexin 43-hemichannel activity in spinal cord astrocytes to attenuate neuropathic pain. J Mol Neurosci,2017,63(1): 58–69. DOI: 10.1007/s12031-017-0957-2
[11] DE LOGU F, GEPPETTI P. Ion channel pharmacology for pain modulation. Handb Exp Pharmacol,2019,260: 161–186. DOI: 10.1007/164_2019_336
[12] QIN S, DU R, YIN S, et al. Nrf2 is essential for the anti-inflammatory effect of carbon monoxide in LPS-induced inflammation. Inflamm Res,2015,64(7): 537–548. DOI: 10.1007/s00011-015-0834-9
[13] AL-OWAIS M M, DALLAS M L, BOYLE J P, et al. Heme oxygenase-1 influences apoptosis via CO-mediated inhibition of K+ channels. Adv Exp Med Biol,2015,860: 343–351. DOI: 10.1007/978-3-319-18440-1_39
[14] BOYCOTT H E, DALLAS M L, ELIES J, et al. Carbon monoxide inhibition of Cav3.2 T-type Ca2+ channels reveals tonic modulation by thioredoxin. FASEB J,2013,27(8): 3395–3407. DOI: 10.1096/fj.13-227249
[15] PEERS C, BOYLE J P, SCRAGG J L, et al. Diverse mechanisms underlying the regulation of ion channels by carbon monoxide. Br J Pharmacol,2015,172(6): 1546–1556. DOI: 10.1111/bph.12760
[16] MCCORD M C, AIZENMAN E. Convergent Ca2+ and Zn2+ signaling regulates apoptotic Kv2.1 K+ currents. Proc Natl Acad Sci U S A,2013,110(34): 13988–13993. DOI: 10.1073/pnas.1306238110
[17] RIEGO G, REDONDO A, LEANEZ S, et al. Mechanism implicated in the anti-allodynic and anti-hyperalgesic effects induced by the activation of heme oxygenase 1/carbon monoxide signaling pathway in the central nervous system of mice with neuropathic pain. Biochem Pharmacol,2018,148: 52–63. DOI: 10.1016/j.bcp.2017.12.007
[18] ALLES S R, GARCIA E, BALASUBRAMANYAN S, et al. Peripheral nerve injury increases contribution of L-type calcium channels to synaptic transmission in spinal lamina Ⅱ: role of α2δ-1 subunits. Mol Pain, 2018, 14: 1744806918765806 [2020-11-03]. https://doi.org/10.1177/1744806918765806.
[19] YAMAMOTO S, TANABE M, ONO H. N- and L-type voltage-dependent Ca2+ channels contribute to the generation of after-discharges in the spinal ventral root after cessation of noxious mechanical stimulation. J Pharmacol Sci,2012,119(1): 82–90. DOI: 10.1254/jphs.12035FP
[20] YAMAMOTO S, SUZUKI Y, ONO H, et al. N- and L-type calcium channels blocker cilnidipine ameliorates neuropathic pain. Eur J Pharmacol,2016,793: 66–75. DOI: 10.1016/j.ejphar.2016.11.001
[21] DALLAS M L, SCRAGG J L, PEERS C. Inhibition of L-type Ca2+ channels by carbon monoxide. Adv Exp Med Biol,2009,648: 89–95. DOI: 10.1007/978-90-481-2259-2_10
[22] TONG L, CAI M, HUANG Y, et al. Activation of K(2)P channel-TREK1 mediates the neuroprotection induced by sevoflurane preconditioning. Br J Anaesth,2014,113(1): 157–167. DOI: 10.1093/bja/aet338
[23] HONORE E. The neuronal background K2P channels: focus on TREK1. Nat Rev Neurosci,2007,8(4): 251–261. DOI: 10.1038/nrn2117
[24] DALLAS M L, SCRAGG J L, PEERS C. Modulation of hTREK-1 by carbon monoxide. Neuroreport,2008,19(3): 345–348. DOI: 10.1097/WNR.0b013e3282f51045
[25] RIDDLE M A, WALKER B R. Regulation of endothelial BK channels by heme oxygenase-derived carbon monoxide and caveolin-1. Am J Physiol Cell Physiol,2012,303(1): 92–101. DOI: 10.1152/ajpcell.00356.2011
[26] FOUNTAIN S J, PARKINSON K, YOUNG M T, et al. An intracellular P2X receptor required for osmoregulation in Dictyostelium discoideum. Nature,2007,448(7150): 200–203. DOI: 10.1038/nature05926
[27] OLIVEIRA S R, FIGUEIREDO-PEREIRA C, DUARTE C B, et al. P2X7 receptors mediate CO-induced alterations in gene expression in cultured cortical astrocytes-transcriptomic study. Mol Neurobiol,2019,56(5): 3159–3174. DOI: 10.1007/s12035-018-1302-7
[28] HOFFMANN L S, CHEN H H. cGMP: transition from bench to bedside: a report of the 6th international conference on cGMP generators, effectors and therapeutic implications. Naunyn Schmiedebergs Arch Pharmacol,2014,387(8): 707–718. DOI: 10.1007/s00210-014-0999-8
[29] LI X, CLARK J D. Spinal cord heme oxygenase participates in glutamate-induced pain-related behaviors. Eur J Pharmacol,2002,450(1): 43–48. DOI: 10.1016/S0014-2999(02)02051-4
[30] STEINER A A, BRANCO L G, CUNHA F Q, et al. Role of the haeme oxygenase/carbon monoxide pathway in mechanical nociceptor hypersensitivity. Br J Pharmacol,2001,132(8): 1673–1682. DOI: 10.1038/sj.bjp.0704014
[31] NASCIMENTO C G, BRANCO L G. Role of the peripheral heme oxygenase-carbon monoxide pathway on the nociceptive response of rats to the formalin test: evidence for a cGMP signaling pathway. Eur J Pharmacol,2007,556(1/2/3): 55–61.
[32] LIANG D, LI X, LIGHTHALL G, et al. Heme oxygenase type 2 modulates behavioral and molecular changes during chronic exposure to morphine. Neuroscience,2003,121(4): 999–1005. DOI: 10.1016/S0306-4522(03)00483-4
[33] LIANG D, LI X, CLARK J D. Increased expression of Ca2+/calmodulin-dependent protein kinase Ⅱ alpha during chronic morphine exposure. Neuroscience,2004,123(3): 769–775. DOI: 10.1016/j.neuroscience.2003.10.007
[34] MANJARREZ E, ROCHA T, ROJAS-PILONI G, et al. Nitric oxide modulates spontaneous cord dorsum potentials in the cat spinal cord. Neurosci Lett,2001,309(1): 5–8. DOI: 10.1016/S0304-3940(01)02004-3
[35] HOHEISEL U, UNGER T, MENSE S. The possible role of the NO-cGMP pathway in nociception: different spinal and supraspinal action of enzyme blockers on rat dorsal horn neurones. Pain,2005,117(3): 358–367. DOI: 10.1016/j.pain.2005.06.023
[36] LEON-PARAVIC C G, FIGUEROA V A, GUZMAN D J, et al. Carbon monoxide (CO) is a novel inhibitor of connexin hemichannels. J Biol Chem,2014,289(52): 36150–36157. DOI: 10.1074/jbc.M114.602243
[37] MORIOKA N, FUJII S, KONDO S, et al. Downregulation of spinal astrocytic connexin43 leads to upregulation of interleukin-6 and cyclooxygenase-2 and mechanical hypersensitivity in mice. Glia,2018,66(2): 428–444. DOI: 10.1002/glia.23255
[38] CHEN G, PARK C K, XIE R G, et al. Connexin-43 induces chemokine release from spinal cord astrocytes to maintain late-phase neuropathic pain in mice. Brain,2014,137(Pt 8): 2193–2209. DOI: 10.1093/brain/awu140
[39] GUO Z, MAN Y, WANG X, et al. Levo-tetrahydropalmatine attenuates oxaliplatin-induced mechanical hyperalgesia in mice. Sci Rep, 2014, 4: 3905[2020-11-03]. https://www.nature.com/articles/srep03905. doi: 10.1038/srep03905.
[40] ZHOU L, AO L, YAN Y, et al. Levo-corydalmine attenuates vincristine-induced neuropathic pain in mice by upregulating the Nrf2/HO-1/CO pathway to inhibit connexin 43 expression. Neurotherapeutics,2020,17(1): 340–355. DOI: 10.1007/s13311-019-00784-7
[41] WU J, ZHANG R, HU G, et al. Carbon monoxide impairs CD11b(+)Ly-6C(hi) monocyte migration from the blood to inflamed pancreas via inhibition of the CCL2/CCR2 axis. J Immunol,2018,200(6): 2104–2114. DOI: 10.4049/jimmunol.1701169
[42] FREITAS A, ALVES-FILHO J C, SECCO D D, et al. Heme oxygenase/carbon monoxide-biliverdin pathway down regulates neutrophil rolling, adhesion and migration in acute inflammation. Br J Pharmacol,2006,149(4): 345–354. DOI: 10.1038/sj.bjp.0706882
[43] MEGIAS J, BUSSEROLLES J, ALCARAZ M J. The carbon monoxide-releasing molecule CORM-2 inhibits the inflammatory response induced by cytokines in Caco-2 cells. Br J Pharmacol,2007,150(8): 977–986. DOI: 10.1038/sj.bjp.0707184
[44] YABLUCHANSKIY A, SAWLE P, HOMER-VANNIASINKAM S, et al. CORM-3, a carbon monoxide-releasing molecule, alters the inflammatory response and reduces brain damage in a rat model of hemorrhagic stroke. Crit Care Med,2012,40(2): 544–552. DOI: 10.1097/CCM.0b013e31822f0d64
[45] JI R R, NACKLEY A, HUH Y, et al. Neuroinflammation and central sensitization in chronic and widespread pain. Anesthesiology,2018,129(2): 343–366. DOI: 10.1097/ALN.0000000000002130
[46] LIDDELOW S A, GUTTENPLAN K A, CLARKE L E, et al. Neurotoxic reactive astrocytes are induced by activated microglia. Nature,2017,541(7638): 481–487. DOI: 10.1038/nature21029
[47] LU K, WU W J, ZHANG C, et al. Carbon monoxide releasing molecule-3 (CORM-3) regulates microglia activity, prevents neuronal injury, and improves memory function during radiation induced brain injury. Curr Neurovasc Res,2020,17(4): 464–470. DOI: 10.2174/1567202617999200730213259
[48] LIN C C, YANG C C, HSIAO L D, et al. Heme oxygenase-1 induction by carbon monoxide releasing molecule-3 suppresses interleukin-1beta-mediated neuroinflammation. Front Mol Neurosci, 2017, 10: 387[2020-11-03]. https://doi.org/10.3389/fnmol.2017.00387.
[49] WILSON J L, BOUILLAUD F, ALMEIDA A S, et al. Carbon monoxide reverses the metabolic adaptation of microglia cells to an inflammatory stimulus. Free Radic Biol Med,2017,104: 311–323. DOI: 10.1016/j.freeradbiomed.2017.01.022
[50] MOTTERLINI R, FORESTI R. Anti-inflammatory activities of carbon monoxide-releasing molecules (CO-RMs) in the brain. Springerplus, 2015, 4(Suppl 1): L41[2020-11-03]. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4797082/. doi: 10.1186/2193-1801-4-S1-L41.
[51] GORDON S, PLÜDDEMANN A. Tissue macrophages: heterogeneity and functions. BMC Biol,2017,15(1): 53. DOI: 10.1186/s12915-017-0392-4
[52] VITALI S H, FERNANDEZ-GONZALEZ A, NADKARNI J, et al. Heme oxygenase-1 dampens the macrophage sterile inflammasome response and regulates its components in the hypoxic lung. Am J Physiol Lung Cell Mol Physiol,2020,318(1): 125–134. DOI: 10.1152/ajplung.00074.2019
[53] LEAKE A, SALEM K, MADIGAN M C, et al. Systemic vasoprotection by inhaled carbon monoxide is mediated through prolonged alterations in monocyte/macrophage function. Nitric Oxide,2020,94: 36–47. DOI: 10.1016/j.niox.2019.10.003
[54] YAMAMOTO-OKA H, MIZUGUCHI S, TODA M, et al. Carbon monoxide-releasing molecule, CORM-3, modulates alveolar macrophage M1/M2 phenotype in vitro. Inflammopharmacology,2018,26(2): 435–445. DOI: 10.1007/s10787-017-0371-y
[55] SAWLE P, FORESTI R, MANN B E, et al. Carbon monoxide-releasing molecules (CO-RMs) attenuate the inflammatory response elicited by lipopolysaccharide in RAW264.7 murine macrophages. Br J Pharmacol,2005,145(6): 800–810. DOI: 10.1038/sj.bjp.0706241
[56] REN K, DUBNER R. Interactions between the immune and nervous systems in pain. Nat Med,2010,16(11): 1267–1276. DOI: 10.1038/nm.2234
[57] ALLISON D J, THOMAS A, BEAUDRY K, et al. Targeting inflammation as a treatment modality for neuropathic pain in spinal cord injury: a randomized clinical trial. J Neuroinflammation,2016,13(1): 152. DOI: 10.1186/s12974-016-0625-4
[58] SHAO Q, LI Y, WANG Q, et al. IL-10 and IL-1β mediate neuropathic-pain like behavior in the ventrolateral orbital cortex. Neurochem Res,2015,40(4): 733–739. DOI: 10.1007/s11064-015-1521-5
[59] SHIMIZU K, BAE S J, HARA T, et al. Involvement of gaseous low molecular monoxides in the cutaneous reverse passive Arthus reaction: cytoprotective action of carbon monoxide. Clin Exp Immunol,2008,153(2): 245–257. DOI: 10.1111/j.1365-2249.2008.03688.x
[60] JI X, PAN Z, LI C, et al. Esterase-sensitive and pH-controlled carbon monoxide prodrugs for treating systemic inflammation. J Med Chem,2019,62(6): 3163–3168. DOI: 10.1021/acs.jmedchem.9b00073