川芎嗪抑制TLR4/MyD88/NF-κB信号通路减轻子宫内膜异位症大鼠炎症反应北大核心CSCD

目的探讨川芎嗪抑制Toll样受体4(TLR4)/髓样分化因子88(MyD88)/核因子κB(NF-κB)信号通路减轻子宫内膜异位症(EMs)大鼠炎症反应的作用。方法自体子宫移植法构建EMs大鼠模型,随机分为EMs组、川芎嗪(低、中、高)剂量组、阳性药物组,每组各12只;进行假手术的12只大鼠作为假手术组。游标卡尺测定异位病灶体积,HE染色检测异位内膜组织病理学改变,ELISA检测血清性激素及炎症因子水平,qRT-PCR、Western blot、免疫荧光染色分别检测异位内膜组织中炎症因子mRNA表达、TLR4/MyD88/NF-κB信号通路相关蛋白表达及NF-κB p65入核情况。结果与假手术组比较,EMs组大鼠异位内膜组织出现明显病理损伤,血清雌二醇(E2)、孕激素(P)含量、肿瘤坏死因子-α(TNF-α)、白介素(IL)-1β、IL-6水平及异位内膜组织中TNF-α、IL-1β、IL-6 mRNA、总蛋白TLR4、MyD88、p-NF-κB p65和核蛋白NF-κB p65表达水平升高,血清促卵泡激素(FSH)、促黄体生成素(LH)含量降低(P<0.05),同时NF-κB p65蛋白大量入核;与EMs组比较,川芎嗪(低、中、高)剂量组和阳性药物组可缓解EMs模型大鼠的上述改变并降低异位病灶体积,且川芎嗪高剂量组和阳性药物组对EMs大鼠的作用效果较好且相近。结论川芎嗪可能通过抑制TLR4/MyD88/NF-κB信号通路激活减轻EMs大鼠炎症反应。     

多发性硬化中TLRs/MyD88/NF-κB信号通路的作用及机制

背景：多发性硬化是以T细胞介导的中枢神经系统慢性炎性脱髓鞘疾病，Toll样受体(Toll-like receptors,TLRs)/髓样分化因子88(myeloid differentiation factor 88,MyD88)/核转录因子κB(nuclear factor kappa-B,NF-κB)信号通路在疾病发生发展过程中有重要作用，探究出信号通路的具体作用机制对进一步治疗该疾病，改善患者的预后至关重要。目的：综述TLRs/MyD88/NF-κB信号通路及其在多发性硬化/实验性自身免疫性脑脊髓炎模型中的作用，并就抑制该信号通路为多发性硬化的治疗提供新的思路和策略。方法：检索中国知网、万方及PubMed数据库在2002年1月至2022年12月与文章主题相关的文献，最终纳入61篇文献进行分析。结果与结论：(1)TLRs/MyD88/NF-κB信号通路是介导炎性免疫反应的重要信号通路；(2)TLRs/MyD88/NF-κB信号通路通过调节树突状细胞的抗原提呈、破坏血脑屏障的完整性、促进T细胞、B细胞和小胶质细胞的激活等途径，在多发性硬化的发展中发挥了重要的作用；(3)通过靶向作用于...     

NF-κB不参与ONO-AE-248诱发的中性粒细胞非凋亡、非坏死性死亡

目的研究核转录因子NF-κB(Nuclear factor kappa B)在ONO-AE-248诱发中性粒细胞非凋亡、非坏死性死亡中的作用,探讨这种细胞死亡的分子机制。方法Ficoll法分离健康志愿者外周静脉血中性粒细胞,与ONO-AE-248共同培养,通过Western blotting检测IκBα的蛋白表达水平,反映NF-κB的活化状态,并应用RT-PCR检测NF-κB调节的基因XIAP、DAD1和FLIP的mRNA表达水平。结果ONO-AE-248不能促进中性粒细胞内IκBα蛋白降解,显示它并不诱导NF-κB活化。而且,ONO-AE-248对NF-κB调节的基因XIAP、DAD1、FLIP的mRNA表达也无明显影响(P>0.05)。结论ONO-AE-248诱发的中性粒细胞非凋亡、非坏死性死亡不依赖NF-κB信号转导通路,其介导中性粒细胞死亡的信号转导可能是不同于凋亡的独特转导途径。     

白芍总苷调控NF-κB/NLRP3信号通路对急性痛风性关节炎大鼠的影响机制研究

目的：探究白芍总苷（TGP）通过调控核因子-κB(NF-κB)/含NLR家族Pyrin域蛋白3(NLRP3)信号通路对急性痛风性关节炎（AGA）大鼠炎症的影响。方法：将60只SD大鼠以每组10只随机分为对照组、AGA组、秋水仙碱组、TGP-L组、TGP-M组、TGP-H组。对照组和AGA组每天进行生理盐水灌胃，秋水仙碱组、TGP-L组、TGP-M组、TGP-H组每天分别灌胃相应药物，共7 d，除对照组外均于灌胃第5天时构建尿酸钠（MSU）诱导的AGA大鼠模型；观察各组大鼠一般情况；检测大鼠步态及关节炎症指数评价、关节肿胀程度；HE染色观察大鼠踝关节滑膜组织病理学变化；ELISA法检测大鼠关节液中炎症因子水平；Western blot检测大鼠踝关节滑膜组织NF-κB p65/NLRP3通路相关蛋白表达情况。结果：与对照组相比，AGA组大鼠关节肿胀、跛行、皮毛无光泽、精神倦怠；秋水仙碱组、TGP-L组、TGP-M组、TGP-H组大鼠相关症状均得到有效改善；与对照组相比，AGA组大鼠步态级别、关节炎症指数、关节肿胀程度、组织病理学程度、TNF-α、IL-6、IL-1β、p-NF-κB p65...     

Toll样受体4介导的抗病毒固有免疫研究进展

Toll样受体(TLR)是一类模式识别受体(PRR),人TLR分布在细胞表面或细胞内。不同TLR识别病原体的不同结构成分后,启动固有免疫反应。其中,TLR4在TLR家族中占有重要地位。它除了识别细菌的脂多糖(LPS)外,还可识别一些病毒的蛋白如水泡性口炎病毒的G糖蛋白、呼吸道合胞病毒的F蛋白。病毒包膜糖蛋白也是TLR4识别的配体。TLR4通过髓样分化因子88(My D88)和β干扰素TIR结构域衔接蛋白(TRIF)途径活化下游核因子κB(NF-κB)、干扰素调节因子3(IRF3)转录因子,产生细胞因子/趋化因子和1型干扰素等,在抗病毒免疫反应、免疫细胞分化及调节、发病机制、药物及疫苗研制等方面具有重要意义。     

Toll样受体4信号转导研究进展

Toll样受体（Toll-like-receptors,TLRs）是一个主要分布于炎症细胞的识别病源分子的受体超家族,其中TLR4主要识别革兰阴性细菌细胞壁成分脂多糖（lipopolysaccharide,LPS）。LPS与TLR4结合后活化髓样分化因子88 (myeloid differentiation factor 88, MyD88)依赖性和非依赖性两条信号途径;前者活化丝裂原激活的蛋白激酶（mitogen-activated protein kinase,MAPK）和核因子-κB（nuclear factor kappa B,NF-κB）信号通路,后者活化NF-κB和干扰素调节因子-3(IFN-regulated factor-3,IRF3)信号通路。通过这些信号途径TLR4诱导炎症细胞释放炎症因子介导炎症反应;同时TLR4通过活化树突状细胞促进抗原递呈,介导先天性免疫向获得性免疫的转化。此外,TLR4能诱导磷脂酰肌醇-3激酶-蛋白激酶B（PI3K-AKT）的信号转导,LPS介导的细胞存活和增殖与TLR4活化 PI3K-AKT途径有关。     

秦皮苷减轻LPS诱导的肺炎小鼠肺组织炎症和氧化损伤

目的研究秦皮苷(fraxin)对脂多糖(lipopolysaccharides,LPS)诱导的肺炎小鼠肺组织炎症和氧化损伤的影响。方法实验分成Control(空白对照)、Model(肺炎模型)、fraxin-A(肺炎模型,8 mg/kg秦皮甙灌胃)、fraxin-B(肺炎模型,16 mg/kg秦皮甙灌胃治疗)、fraxin-C组(肺炎模型,32 mg/kg秦皮甙灌胃)。取肺组织和肺泡灌洗液,检测肺组织湿/干重比例,计数肺泡灌洗液细胞总数和中性粒细胞数目;ELISA法检测肺泡灌洗液中白细胞介素-6(interleukin-6,IL-6)、白细胞介素-1β(interleukin-1β,IL-1β)、肿瘤坏死因子-α(tumor necrosis factor-α,TNF-α)、白细胞介素-10(interleukin-10,IL-10)含量;比色法检测肺泡灌洗液中超氧化物歧化酶(superoxide orgotein dismutase,SOD)和一氧化氮(nitric oxide,NO)含量;可见分光光度法检测肺泡灌洗液中丙二醛(malonaldehyde,MDA)含量;Western blot法检测肺组织中p-NF-κBp65、核转录因子-κB(nuclear factor-kappaB,NF-κB)p65、Toll样受体4(Toll-like receptor-4,TLR4)、诱导型一氧化氮合成酶(inducible nitric oxide synthase,iNOS)、p-IκBα、IκBα蛋白表达。结果与Control组比较,Model组肺组织湿/干重比例升高,肺泡灌洗液细胞总数和中性粒细胞数目增多,肺泡灌洗液中IL-6、IL-1β、TNF-α含量和MDA、NO含量升高,SOD含量下降,肺组织中NF-κBp65、TLR4、i NOS蛋白水平升高。与Model组比较,fraxin-A、fraxin-B、fraxin-C组肺组织湿/干重比例降低,肺泡灌洗液细胞总数和中性粒细胞数目减少,肺泡灌洗液中IL-6、IL-1β、TNF-α含量和MDA、NO含量降低,SOD含量升高,肺组织中NF-κBp65、TLR4、iNOS蛋白水平降低。结论秦皮苷减轻LPS诱导的肺炎小鼠肺组织炎症和氧化损伤,其机制可能与TLR4/NF-κB有关。     

依维莫司对大鼠实验性IgA肾病的作用

目的:观察依维莫司对大鼠实验性Ig A肾病的作用并初步探讨其机制。方法:建立实验性Ig A肾病大鼠模型,实验共分为正常对照(control)组、模型组(Ig A组)和依维莫司给药组;测定给药后各组大鼠尿红细胞、尿蛋白和尿N-乙酰-β-D-氨基葡萄糖苷酶(NAG)的含量;免疫荧光染色检测肾组织中Ig A沉淀情况;Western blot法检测髓样分化因子88(My D88)、TLR4、NF-κB、IL-4和IL-13的蛋白表达水平;实时荧光定量PCR检测IL-4与IL-13的mRNA表达水平。结果:依维莫司能够抑制实验性Ig A肾病大鼠尿红细胞、尿蛋白和尿NAG含量的升高,抑制My D88、TLR4、NF-κB和IL-4和IL-13蛋白表达水平的上调,以及抑制IL-4和IL-13 mRNA表达水平的上调。结论:依维莫司能降低Ig A肾病大鼠尿红细胞、尿蛋白和尿NAG含量,其作用可能与其调节My D88、TLR4、NF-κB、IL-4与IL-13的表达有关。     

毒热平注射液对吞噬细胞系Ana-1核因子-κB的影响

目的:研究毒热平注射液对流感病毒感染的小鼠腹腔巨噬细胞株Ana-1细胞核因子-κB(NF-κB)活性的影响。方法:用100TCID50流感病毒亚甲型鼠肺适应株A/FM/1/47(H1N1)感染小鼠腹腔巨噬细胞株Ana-1后换用10mg/L和1mg/L浓度含药维持液继续培养,分别于12h和24h弃细胞上清液并收集细胞,提取巨噬细胞RNA和核蛋白,进行实时定量PCR反应(RT-PCR)和Western blot实验,动态测定毒热平注射液对病毒感染前后巨噬细胞Toll样受体7(TLR7)、髓样分化因子88(MyD88)mRNA和NF-κBp65mRNA及其蛋白表达水平的影响。结果:毒热平注射液可剂量依赖性地下调病毒感染巨噬细胞TLR7、MyD88mRNA的表达、NF-κBp65mRNA及其蛋白表达水平。结论:毒热平注射液能通过调节MyD88依赖的信号传导通路下调细胞核因子-κB活性发挥抗病毒感染作用。     

Annexin A1 promotes timely resolution of inflammation in murine gout

Gout is a self‐limited inflammatory disease caused by deposition of monosodium urate (MSU) crystals in the joints. Resolution of inflammation is an active process leading to restoration of tissue homeostasis. Here, we studied the role of Annexin A1 (AnxA1), a glucocorticoid‐regulated protein that has anti‐inflammatory and proresolving actions, in resolution of acute gouty inflammation. Injection of MSU crystals in the knee joint of mice induced inflammation that was associated with expression of AnxA1 during the resolving phase of inflammation. Neutralization of AnxA1 with antiserum or blockade of its receptor with BOC‐1 (nonselective) or WRW₄ (selective) prevented the spontaneous resolution of gout. There was greater neutrophil infiltration after challenge with MSU crystals in AnxA1 knockout mice (AnxA1^?/?) and delayed resolution associated to decreased neutrophil apoptosis and efferocytosis. Pretreatment of mice with AnxA1‐active N‐terminal peptide (Ac_2–26) decreased neutrophil influx, IL‐1β, and CXCL1 production in periarticular joint. Posttreatment with Ac_2–26 decreased neutrophil accumulation, IL‐1β, and hypernociception, and improved the articular histopathological score. Importantly, the therapeutic effects of Ac_2–26 were associated with increased neutrophils apoptosis and shortened resolution intervals. In conclusion, AnxA1 plays a crucial role in the context of acute gouty inflammation by promoting timely resolution of inflammation.     

Macrophage-derived IL-1β enhances monosodium urate crystal-triggered NET formation

Objective and design

Arthritic gout is caused by joint inflammation triggered by the damaging effects of monosodium uric acid (MSU) crystal accumulation in the synovial space. Neutrophils play a major role in mediating joint inflammation in gout. Along with neutrophils, other immune cells, such as macrophages, are present in inflamed joints and contribute to gout pathogenesis. Neutrophils form neutrophil extracellular traps (NETs) in response to MSU crystals. In the presence of MSU crystals, macrophages release IL-1β, a cytokine crucial to initiate gout pathogenesis and neutrophil recruitment. Our research investigated interactions between human macrophages and neutrophils in an in vitro model system and asked how macrophages affect NET formation stimulated by MSU crystals.

Materials or subjects

Human neutrophils and PBMCs were isolated from peripheral blood of healthy volunteers. PBMCs were differentiated into macrophages in vitro using human M-CSF.

Treatment

Human neutrophils were pretreated with macrophage-conditioned media, neutrophil-conditioned media, recombinant human IL-1β or anakinra prior to stimulation by MSU crystals.

Method

Interaction of neutrophils with MSU crystals was evaluated by live imaging using confocal microscopy. The presence of myeloperoxidase (MPO) and neutrophil elastase (NE) was measured by ELISA. NET formation was quantitated by Sytox Orange-based extracellular DNA release assay and NE-DNA ELISA. AggNET formation was assessed by macroscopic evaluation.

Results

We found that crystal- and cell-free supernatants of macrophages stimulated with MSU crystals promote MSU crystal-stimulated NET formation in human neutrophils. This observation was confirmed by additional assays measuring the release of MPO, NE, and the enzymatic activity of NE. MSU crystal-induced NET formation remained unchanged when neutrophil supernatants were tested. IL-1β is a crucial cytokine orchestrating the onset of inflammation in gout and is known to be released in large amounts from macrophages following MSU crystal stimulation. We found that recombinant IL-1β strongly promoted MSU crystal-induced NET formation in human neutrophils. Interestingly, IL-1β alone did not induce any NET release. We also found that clinical grade anakinra, an IL-1 receptor blocker, strongly reduced the NETosis-enhancing effect of macrophage supernatants indicating that IL-1β is mainly responsible for this effect.

Conclusions

Macrophage-derived IL-1β enhances MSU crystal-induced NET release in neutrophils. We identified a new mechanism by which macrophages and IL-1β affect neutrophil functions, and could contribute to the inflammatory conditions present in gout. Our results also revealed a new anti-inflammatory mechanism of anakinra.

     

Monosodium urate crystals induced ICAM-1 expression and cell–cell adhesion in renal mesangial cells: Implications for the pathogenesis of gouty nephropathy

BackgroundRenal disease is prevalent in gouty patients and monosodium urate (MSU) crystal deposition in the kidney can be detected in some gouty nephropathy patients. MSU crystals can induce inflammatory events, we investigated the MSU-induced expression of intercellular adhesion molecule (ICAM)-1 on human renal mesangial cells (HRMCs) and the involved signal transduction mechanisms.MethodsThe HRMCs cell line was purchased from ScienCell Research Laboratories. MSU crystals were made by dissolving uric acid in sodium hydroxide (NaOH) solution. The involvement of MAPKs, apoptosis-associated speck-like protein containing a CARD domain (ASC), and Toll-like receptor (TLR) was investigated using pharmacological inhibitors, transfection with short hairpin RNA (shRNA), or monoclonal antibodies. Protein expression was evaluated by Western blotting. The functional activity of ICAM-1 was evaluated with cell–cell adhesion assay and immunofluorescence analysis.ResultsMSU stimulation increased expression of ICAM-1 and adhesion between HRMCs and human monocytic THP-1 cells. The interaction between HRMCs and THP-1 was suppressed by ICAM-1 neutralizing antibodies. MSU stimulation induced activation of mitogen-activated protein kinases, including c-Jun N-terminal kinase (JNK), p38, and extracellular signal-regulated kinase (ERK), but only p38 was responsible for MSU-induced expression of ICAM-1 and cell–cell adhesion. ASC also play a role in MSU-induced effects. Pretreatment with monoclonal antibodies against toll-like receptor (TLR)2 or TLR4 reduced MSU-induced ICAM-1 expression, cell–cell adhesion, p38 phosphorylation but the reduction of ASC activation is insignificant.ConclusionThe MSU induced ICAM-1 expression on HRMCs and cell–cell adhesion involved TLR2/4-p38-ICAM1 pathway and TLR2/4 independent ASC-p38-ICAM1 axis. These findings might partly explain the mechanisms underlying gouty nephropathy.     

MD-2 regulates LPS-induced NLRP3 inflammasome activation and IL-1beta secretion by a MyD88/NF-κB-dependent pathway in alveolar macrophages cell line

Myeloid differentiation protein 2 (MD-2) is required in the recognition of lipopolysaccharide (LPS) by toll-like receptor 4 (TLR4), and participates in LPS-induced alveolar macrophage (AM) inflammation during acute lung injury (ALI). Activation of the NOD-like receptor family, pyrin domain containing 3 (NLRP3) inflammasome aggravates inflammation in LPS-induced ALI. However, there is currently little known about the relationship between MD-2 signaling and the NLRP3 inflammasome. This study showed that NLRP3 expression, IL-1beta (IL-1β) secretion, and pyroptosis were up-regulated after LPS stimulation in the NR8383 AM cell-line. MD-2 gene knock-down reduced LPS-induced mRNA and protein expression of NLRP3 and IL-1β secretion in NR8383 cells, and inhibited the MyD88/NF-κB signaling pathway. Conversely, over-expression of MD-2 not only heightened NLRP3, MyD88, and NF-κB p65 protein expression, it also aggravated the LPS-induced inflammatory response. Furthermore, the NF-κB inhibitor SN50 had a beneficial role in decreasing NLRP3 and caspase-1 mRNA and protein expression. The observations suggest that MD-2 helps to regulate LPS-induced NLRP3 inflammasome activation and the inflammatory response in NR8383 cells, and likely does so by affecting MyD88/NF-κB signaling.     

天抗(TK)对脂多糖诱导小鼠炎症模型的抗炎作用及其机制

目的研究天抗(TK)对脂多糖(LPS)诱导的小鼠炎症模型的抗炎作用及机制研究。方法将42只昆明小鼠随机分为正常对照(NC)组、模型对照(LPS)组、地塞米松(DXM)组、天抗低(TK-L)、中(TK-M)和高(TK-H)剂量组(0.2,0.8和3.2 g/kg)。各组分别灌胃给药7 d后,腹腔注射30 mg/kg的LPS诱导小鼠急性炎性模型,6 h后处死小鼠,检测小鼠脾脏指数,ELISA测定小鼠血清中IL-1β、IL-6和TNF-α的表达水平;生化法检测小鼠血清中SOD和MDA的表达;qRT-PCR检测小鼠脾脏TLR4、MyD88、TRAF6、p65、IL-1β、IL-6和TNF-αmRNA的表达水平;Western blot检测小鼠脾脏TLR4、MyD88、TRAF6、p-p65和p65蛋白表达水平。结果与LPS组相比,TK组小鼠的脾脏指数明显降低,血清和脾脏组织中IL-1β、IL-6、TNF-α和MDA水平显著下降,SOD水平明显升高,小鼠脾脏组织的TLR4、MyD88、TRAF6和p-p65等蛋白及mRNA表达水平均明显降低。结论天抗对LPS诱导的小鼠急性炎症模型具有抗炎作用,其作用机制可能是通过TLR4/MyD88/NF-κB(p-65)信号通路抑制炎症因子的释放。     

醋酸泼尼松对糖尿病肾病模型大鼠肾功能、肾脏炎性反应及AMPK/SIRT1信号通路的影响

目的 探究醋酸泼尼松对糖尿病肾病(DN)大鼠肾脏炎性反应及腺苷酸活化蛋白激酶(AMPK)/沉默信息调节因子1(SIRT1)信号通路的影响.方法 随机选取12只大鼠作为对照组,将其余大鼠用高糖高脂饲料辅以腹腔注射链脲佐菌素(STZ)构建DN大鼠模型.将造模成功大鼠随机分为模型组、醋酸泼尼松低(6.25 mg/kg)、高(...     

Diverse roles of TGF-β receptor II in renal fibrosis and inflammation in vivo and in vitro

TGF-β1 binds receptor II (TβRII) to exert its biological activities but its functional importance in kidney diseases remains largely unclear. In the present study, we hypothesized that TβRII may function to initiate the downstream TGF-β signalling and determine the diverse role of TGF-β1 in kidney injury. The hypothesis was examined in a model of unilateral ureteral obstructive (UUO) nephropathy and in kidney fibroblasts and tubular epithelial cells in which the TβRII was deleted conditionally. We found that disruption of TβRII inhibited severe tubulointerstitial fibrosis in the UUO kidney, which was associated with the impairment of TGF-β/Smad3 signalling, but not with the ERK/p38 MAP kinase pathway. In contrast, deletion of TβRII enhanced NF-κB signalling and renal inflammation including up-regulation of Il-1β and Tnfα in the UUO kidney. Similarly, in vitro disruption of TβRII from kidney fibroblasts or tubular epithelial cells inhibited TGF-β1-induced Smad signalling and fibrosis but impaired the anti-inflammatory effect of TGF-β1 on IL-1β-stimulated NF-κB activation and pro-inflammatory cytokine expression. In conclusion, TβRII plays an important but diverse role in regulating renal fibrosis and inflammation. Impaired TGF-β/Smad3, but not the non-canonical TGF-β signalling pathway, may be a key mechanism by which disruption of TβRII protects against renal fibrosis. In addition, deletion of TβRII also enhances NF-κB signalling along with up-regulation of renal pro-inflammatory cytokines, which may be associated with the impairment of anti-inflammatory properties of TGF-β1.     

PMA and crystal‐induced neutrophil extracellular trap formation involves RIPK1‐RIPK3‐MLKL signaling

Neutrophil extracellular trap (NET) formation contributes to gout, autoimmune vasculitis, thrombosis, and atherosclerosis. The outside‐in signaling pathway triggering NET formation is unknown. Here, we show that the receptor‐interacting protein kinase (RIPK)‐1‐stabilizers necrostatin‐1 or necrostatin‐1s and the mixed lineage kinase domain‐like (MLKL)‐inhibitor necrosulfonamide prevent monosodium urate (MSU) crystal‐ or PMA‐induced NET formation in human and mouse neutrophils. These compounds do not affect PMA‐ or urate crystal‐induced production of ROS. Moreover, neutrophils of chronic granulomatous disease patients are shown to lack PMA‐induced MLKL phosphorylation. Genetic deficiency of RIPK3 in mice prevents MSU crystal‐induced NET formation in vitro and in vivo. Thus, neutrophil death and NET formation may involve the signaling pathway defining necroptosis downstream of ROS production. These data imply that RIPK1, RIPK3, and MLKL could represent molecular targets in gout or other crystallopathies.     

Osteoblast retraction induced by adherent neutrophils promotes osteoclast bone resorption: implication for altered bone remodeling in chronic gout

Bone destruction in chronic gout is correlated with deposits of monosodium urate (MSU) crystals. Bone with MSU tophi were histopathologically shown to have altered remodeling and cellular distribution. We investigated the impact of neutrophils in bone remodeling associated with MSU and demonstrated that neutrophils, through elastase localized at their surface, induced retraction of confluent osteoblasts (OBs) previously layered on calcified matrix. This OB retraction allowed osteoclasts to resorb cell-free areas of the matrix. This neutrophil effect was concentration dependent and time dependent and required direct contact with OBs. Exposure of OBs to MSU greatly promoted neutrophil adherence to OBs. Neutrophil membrane at the contact zone with OBs showed concentrated fluorescence of dye PKH-67, indicating a cellular contact. Neutrophil-OB interaction increased the survival of neutrophils, reduced their release of lactoferrin in presence of MSU and did not change OB-mediated mineralization. The adhesion of neutrophils to OBs was heterotypic through neutrophil CD29/CD49d and OB-fibronectin peptide CS1. Leukotriene B? (LTB?) and platelet-activating factor (PAF) were also involved in neutrophil adherence to OBs, as shown by the blocking effect of selective LTB? and PAF receptor antagonists, and a cytosolic phospholipase A(2α) (cPLA(2α)) inhibitor. Blockade of CD49d/CS1 and inhibition of the cPLA(2α) had subadditive effects, reducing by 60% the adherence of neutrophils to OBs. Taken together, these data showed that neutrophil adhesion to MSU-activated OBs was mediated by the β? integrin CD29/CD49d-fibronectin peptide CS1 receptors and cPLA(2α)-derived metabolites and impacts on OB and osteoclast functions. These interactions could be involved in the local bone remodeling process of gout.