Cardiac overexpression of monocyte chemoattractant protein-1 in transgenic mice prevents cardiac dysfunction and remodeling after myocardial infarction

Myocardial infarction (MI) is accompanied by inflammatory responses that lead to the recruitment of leukocytes and subsequent myocardial damage, healing, and scar formation. Because monocyte chemoattractant protein-1 (MCP-1) (also known as CCL2) regulates monocytic inflammatory responses, we investigated the effect of cardiac MCP-1 overexpression on left ventricular (LV) dysfunction and remodeling in a murine MI model. Transgenic mice expressing the mouse JE-MCP-1 gene under the control of the alpha-cardiac myosin heavy chain promoter (MHC/MCP-1 mice) were used for this purpose. MHC/MCP-1 mice had reduced infarct area and scar formation and improved LV dysfunction after MI. These mice also showed induction of macrophage infiltration and neovascularization; however, few bone marrow-derived endothelial cells were detected in MHC/MCP-1 mice whose bone marrow was replaced with that of Tie2/LacZ transgenic mice. Flow cytometry analysis showed no increase in endothelial progenitor cells (CD34+/Flk-1+ cells) in MHC/MCP-1 mice. Marked myocardial interleukin (IL)-6 secretion, STAT3 activation, and LV hypertrophy were observed after MI in MHC/MCP-1 mice. Furthermore, cardiac myofibroblasts accumulated after MI in MHC/MCP-1 mice. In vitro experiments revealed that a combination of IL-6 with MCP-1 synergistically stimulated and sustained STAT3 activation in cardiomyocytes. MCP-1, IL-6, and hypoxia directly promoted the differentiation of cardiac fibroblasts into myofibroblasts. Our results suggest that cardiac overexpression of MCP-1 induced macrophage infiltration, neovascularization, myocardial IL-6 secretion, and accumulation of cardiac myofibroblasts, thereby resulting in the prevention of LV dysfunction and remodeling after MI. They also provide a new insight into the role of cardiac MCP-1 in the pathophysiology of MI.     

Abnormal monocyte recruitment and collateral artery formation in monocyte chemoattractant protein-1 deficient mice

Monocyte chemoattractant protein 1 (MCP-1) has been shown to be effective for the stimulation of collateral artery formation in small and large animal models. The availability of a genetic knockout mouse enables evaluation of the importance of the role of MCP-1 in the natural course of collateral artery growth. In a total of 21 MCP-1 -/- as well as 13 of the appropriate genetic background controls ([129Sv/J X C57BI/6J]F1), a femoral artery ligation was performed. Subsequently, a polyethylene catheter, connected to an osmotic minipump, was inserted retrogradely into the occluded femoral artery with the tip pointing upstream. Using this technique, PBS (MCP-1 -/-: n = 13 and C57BI/6J: n = 13) or MCP-1 (JE; MCP-1 -/-: n = 8) was delivered intra-arterially. Seven days after ligation, determination of hind limb flow was assessed by controlled tissue perfusion using differently labeled fluorescent microspheres. MCP-1 -/- mice exhibited a reduction of hind limb flow of 32.9 +/- 9.2% of the unligated hind limb, compared with 55.4 +/- 6.8% in C57BI/6J mice (p<0.01). MCP-1 -/- mice that underwent a subsequent 'rescue' treatment with MCP-1 showed a restoration of flow to a level of 47.4 +/- 9.8% (p = NS compared with PBS-treated C57BI/6J). Specific immunohistochemical staining for monocytes (MOMA-2: MCP-1 -/-, n = 5 and C57BI/6J, n = 5) showed a reduced number of monocytes around developing collateral arteries in the MCP-1 -/- mice. In conclusion, our data show that the absence of MCP-1 causes a strong reduction in flow restoration after femoral artery occlusion, coinciding with a reduced monocyte attraction, emphasizing the central role of this chemokine in the multifactorial process of collateral artery formation.     

单核细胞趋化蛋白-1在系统性硬化症患者中的表达

目的 探讨单核细胞趋化蛋白-1（MCP-1）在系统性硬化症（SSc）的相关性。方法 采用酶联免疫吸附试验（ELISA）方法检测27例SSc患者血浆MCP-1水平，并与21名年龄和性别相匹配的健康志愿者血浆中浓度对照，同时采用反转录聚合酶链反应（RT-PCR）和免疫组织化学染色方法检测MCP-1mRNA和蛋白质在5例SSc患者和3名健康志愿者皮肤成纤维细胞中的表达。结果 血浆MCP-1水平SSc组为（787±393）pg／ml，明显高于健康志愿者组的（426±266）pg/ml（P〈0．05）。对SSc组的进一步分析显示，11例弥漫型SSc患者血浆MCP-1水平为（896±347）pg／ml，高于16例局限型SSc患者的（714±332）pg/ml（P〈0．05）；18例并发有肺间质纤维化的SSc患者血浆MCP-1水平（844±327）pg／ml，也高于9例无肺间质纤维化的SSc患者的（676±314）pg／ml（P〈0．05）。RT-PCR和免疫组织化学染色的结果显示，5例分离于SSc病变皮肤、在体外培养的成纤维细胞有MCP-1的mRNA和蛋白质分子表达，而3名取自健康志愿者皮肤的成纤维细胞则无表达。结论 SSc患者血浆MCP-1水平显著升高，而且与皮肤受累程度和肺间质纤维化有一定的关系。RT-PCR和免疫组织化学染色结果表明，SSc患者病变皮肤组织表达MCP-1增高，提示MCP-1在SSc的病程中起重要作用。     

Serum of cytomegalovirus-infected mice induces monocyte chemoattractant protein-1 expression by endothelial cells

Inflammation plays a central role in atherogenesis. It was hypothesized that infection of apolipoprotein E-deficient mice with murine cytomegalovirus (MCMV) increases serum levels of proinflammatory cytokines, which may induce "proatherosclerotic" changes in endothelial cells (ECs). Serum samples were collected from uninfected and infected mice. ELISA was used to determine cytokine serum levels and monocyte chemoattractant protein-1 (MCP-1) levels in the supernatant of mouse ECs incubated with serum-containing medium. Serum samples from infected mice induced MCP-1 expression by ECs. These serum samples contain interferon (IFN)-gamma, whereas IFN-gamma was undetectable in serum samples from uninfected mice. Preincubating infected mouse serum with anti-IFN-gamma monoclonal antibody significantly decreased serum-induced EC expression of MCP-1. Thus, MCMV infection increases IFN-gamma serum levels, such serum can induce MCP-1 in ECs, and the serum-induced MCP-1 expression is due, at least in part, to IFN-gamma. If these changes in EC function also occur in vivo in response to infection, they could exacerbate atherogenesis.     

Exendin-4 improves cardiac function in mice overexpressing monocyte chemoattractant protein-1 in cardiomyocytes

The incretin hormone glucagon-like peptide-1 (Glp1) is cardioprotective in models of ischemia-reperfusion injury, myocardial infarction and gluco/lipotoxicity. Inflammation is a factor in these models, yet it is unknown whether Glp1 receptor (Glp1r) agonists are protective against cardiac inflammation. We tested the hypothesis that the Glp1r agonist Exendin-4 (Ex4) is cardioprotective in mice with cardiac-specific monocyte chemoattractant protein-1 overexpression. These MHC-MCP1 mice exhibit increased cardiac monocyte infiltration, endoplasmic reticulum (ER) stress, apoptosis, fibrosis and left ventricular dysfunction. Ex4 treatment for 8 weeks improved cardiac function and reduced monocyte infiltration, fibrosis and apoptosis in MHC-MCP1 mice. Ex4 enhanced expression of the ER chaperone glucose-regulated protein-78 (GRP78), decreased expression of the pro-apoptotic ER stress marker CCAAT/-enhancer-binding protein homologous protein (CHOP) and increased expression of the ER calcium regulator Sarco/Endoplasmic Reticulum Calcium ATPase-2a (SERCA2a). These findings suggest that the Glp1r is a viable target for treating cardiomyopathies associated with stimulation of pro-inflammatory factors.     

The chemokine monocyte chemoattractant protein-1 induces functional responses through dimerization of its receptor CCR2

Cytokines interact with hematopoietin superfamily receptors and stimulate receptor dimerization. We demonstrate that chemoattractant cytokines (chemokines) also trigger biological responses through receptor dimerization. Functional responses are induced after pairwise crosslinking of chemokine receptors by bivalent agonistic antichemokine receptor mAb, but not by their Fab fragments. Monocyte chemoattractant protein (MCP)-1-triggered receptor dimerization was studied in human embryonic kidney (HEK)-293 cells cotransfected with genes coding for the CCR2b receptor tagged with YSK or Myc sequences. After MCP-1 stimulation, immunoprecipitation with Myc-specific antibodies revealed YSK-tagged receptors in immunoblotting. Receptor dimerization also was validated by chemical crosslinking in both HEK-293 cells and the human monocytic cell line Mono Mac 1. Finally, we constructed a loss-of-function CCR2bY139F mutant that acted as a dominant negative, blocking signaling through the CCR2 wild-type receptor. This study provides functional support for a model in which the MCP-1 receptor is activated by ligand-induced homodimerization, allowing discussion of the similarities between bacterial and leukocyte chemotaxis.     

单核细胞趋化蛋白-1与糖尿病肾病

糖尿病肾病(DN)是终末肾功能衰竭的主要原因,主要的病理改变是肾小球肥大、细胞外基质积聚以及肾小球硬化.多种机制参与了DN的发生、发展,其中肾脏被炎性反应细胞如单核/巨噬细胞浸润是DN的标志之一.单核细胞趋化蛋白-1(MCP-1)是一种对单核细胞具有特异趋化功能的细胞因子,参与单核/巨噬细胞的浸润,在DN的发生、发展中起重要作用.     

Potential roles of CCL2/monocyte chemoattractant protein-1 in the pathogenesis of cutaneous sclerosis

Scleroderma is a connective tissue disease of unknown etiology characterized by the excessive deposition of extracellular matrix in the skin. Cellular infiltrates of certain immune cells and pro-inflammatory mediators are suggested to play a crucial role in cutaneous fibrosis, forming complicated networks between fibroblasts and immune cells and/or cell-cell communications. Tissue-selective trafficking of leukocytes is mediated by combinations of adhesion molecules and chemokines. Although chemokines and their receptors are considered to be mediators of inflammation and fibrosis in scleroderma, their pathophysiological role remains incompletely understood. Recent studies suggest that CCL2/monocyte chemoattractant protein-1 plays an important role in the fibrotic process, including liver fibrosis, pulmonary fibrosis, and scleroderma. This review summarizes recent findings of the potential roles of CCL2 in cutaneous sclerosis in experimental animal models of scleroderma as well as human scleroderma.     

Expression of monocyte chemoattractant protein-1 in idiopathic dilated cardiomyopathy

Atrial fibrillation (AF) is the most common arrhythmia in clinical practices. Mediated by muscarinic type 2 receptors (M(2)Rs), acetylcholine affects electrophysiological activities of atrial myocytes and may contribute to the onset of AF. In order to characterize the distribution of M(2)Rs in the atrial myocardium, different atrial regions in both the SD rat and human were dissected. Atrial myocytes were isolated with type II collagenase. The M(2)Rs expression in these atrial tissues and myocytes was detected by immunofluorescent staining and confocal laser scanning biological microscope. The results showed the highest density of M(2)Rs in atrial myocytes of the left atrial posterior wall. It is concluded that there is a marked spatial heterogeneity in the expression of the M(2)Rs in the atrium, which might create a substrate that would favor the initiation and maintenance of acetylcholine-induced AF.     

Roles of endogenous monocyte chemoattractant protein-1 in ischemia-induced neovascularization

OBJECTIVES: We sought to investigate the role of endogenous monocyte chemoattractant protein (MCP)-1 in ischemia-induced neovascularization. BACKGROUND: Roles of inflammatory changes including macrophage infiltration are suggested in ischemic neovascularization. METHODS: Unilateral hindlimb ischemia was induced by excising surgically the entire femoral artery and vein in mice. Immediately after operation, plasmid deoxyribonucleic acid encoding a dominant negative mutant of MCP-1 (7ND) or the empty plasmid (mock) was injected into the ipsilateral thigh adductor muscle. RESULTS: In mock-treated mice, MCP-1 was upregulated transiently in ischemic hindlimb peaking at day 3. Serial laser Doppler blood flow (LDBF) analysis showed an abrupt decrease in blood flow, followed by a recovery to the near-normal levels in mock-treated mice; 7ND treatment had no effects on the initial decrease in LDBF but deteriorated the recovery. At day 3, macrophage infiltration and inductions of tumor necrosis factor (TNF)-alpha and vascular endothelial growth factor (VEGF) were prominent in the ischemic adductor muscle in mock-treated mice; 7ND treatment significantly reduced macrophage infiltration and suppressed TNF-alpha and VEGF inductions in response to ischemia. At day 21, postmortem angiography and anti-CD31 immunohistostaining revealed well-developed collateral vessels and capillary formation, respectively, in the ischemic muscle of mock-treated mice; 7ND overexpression remarkably suppressed the collateral vessel formation and capillary formation. CONCLUSIONS: Endogenous MCP-1 may play a role in ischemia-induced neovascularization by recruiting macrophages that activate TNF-alpha and VEGF inductions.     

单核细胞趋化蛋白-1在BXSB狼疮小鼠肾组织中表达及药物干预效应

目的研究单核细胞趋化蛋白-1(MCP-1)在BXSB狼疮小鼠肾组织中的表达情况并探讨甲泼尼龙(MPS)是否可抑制MCP-1表达而缓解狼疮肾炎(LN)。方法应用双缩脲法、反转录聚合酶链反应(RT-PCR)、免疫组织化学法及医学图像分析系统检测各组小鼠(BXSB狼疮小鼠MPS治疗组和对照组、BALB/C正常对照组小鼠)24h尿蛋白、肾组织MCP-1的表达,并分析其与24h尿蛋白之间的相关性。结果BXSB狼疮小鼠肾组织MCP-1表达较正常BALB/C小鼠增高,以肾小管更为明显,且肾小管MCP-1的表达与24h尿蛋白呈正相关(P<0.01);甲泼尼龙干预后,MCP-1表达明显减弱(P<0.01),且肾小管MCP-1表达的下降与24h尿蛋白降低呈正相关(P<0.01)。结论MCP-1可能参与介导BXSB狼疮小鼠LN的发生发展;甲泼尼龙可通过抑制肾组织MCP-1的表达,减轻蛋白尿,可能是缓解LN作用机制之一。     

结直肠癌趋化因子单核细胞超化蛋白-1的表达

目的：通过检测结直肠癌组织中单核细胞超化蛋白－1（MPC－1）的表达情况，研究MCP－1的表达与结直肠癌生物学行为的关系。方法：采用RT－PCR方法，检测临床收集的新鲜结肠癌组织标本中MCP－1mRNA的表达；采用免疫组化方法，检测结直肠癌组织中MCP－1蛋白的表达，结果：12例结直肠癌组织均可出现MCP－1mRNA的表达，40例结直肠癌组织MCP－1蛋白表达的阳性率为90％，结直肠癌组织MCP－1蛋白的表达与结直肠癌的转移及Dukes分期有关，表达强者，转移发生率低，Dukes分期早，结论：结直肠组织中MCP－1的表达能影响结直肠癌的生物学行为。     

Eotaxin and monocyte chemoattractant protein-1 in chronic eosinophilic pneumonia.

Chronic eosinophilic pneumonia (CEP) is characterized by chronic or recurrent pulmonary infiltrates with eosinophils, but the precise mechanism of eosinophil accumulation has not been fully elucidated. Eotaxin is one of the CC chemokines that selectively recruits eosinophils and contributes to the pathogenesis of allergic airway diseases including asthma, but its roles in pathogenesis of CEP have not been fully elucidated. The authors measured concentrations of eotaxin and other CC chemokines, monocyte chemoattractant protein-1 (MCP-1), regulated on activation, normal T-cell expressed and secreted, macrophage inflammatory protein-1alpha, and the eosinophil activating Th2 cytokine interleukin (IL)-5 in bronchoalveolar lavage (BAL) fluid from CEP patients (n=11), and compared these concentrations with those from control subjects (n = 6). The eotaxin (904 +/- 203 versus 29 +/- 7 pg x mL(-1), p = 0.0001), MCP-1 (194 +/- 57 versus 15 +/- 2 pg x mL(-1), p < 0.05), and IL-5 (7.8 +/- 2.0 versus 2.7 +/- 0.6 pg x mL(-1), p < 0.05) levels were significantly higher for cases with CEP in comparison to those serving as controls. Proportions of eosinophil and lymphocyte counts were greater in BAL fluid from CEP patients. Eotaxin and IL-5 levels correlated with the proportion of eosinophils in BAL fluid from CEP patients. MCP-1 correlated with the relative lymphocyte numbers. In short, eotaxin, interleukin-5, and monocyte chemoattractant protein-1 levels were higher in the BAL fluid of CEP patients and these levels may contribute to eosinophil and lymphocyte recruitment and activation in the airways as found with this disorder.     

Doxycycline decreases monocyte chemoattractant protein-1 in human lung epithelial cells

Certain antibiotics possess anti-inflammatory properties and could potentially be used to treat inflammatory lung diseases associated with an influx of monocytes such as panbronchiolitis, asthma, cystic fibrosis, and bronchitis. Doxycycline is reported to possess anti-inflammatory effects. Monocyte chemoattractant protein-1 (MCP-1) is a major inflammatory cytokine and a powerful chemoattractant for monocytes. The authors hypothesized that doxycycline exerts its anti-inflammatory effects, in part, by reducing MCP-1 production. To test this hypothesis, A549 human lung epithelial cells were stimulated with cytomix in the presence or absence of doxycycline. In stimulated cells doxycycline decreased MCP-1 production by 95% and in monocyte chemotaxis assays migration decreased by 55%. However, doxycycline did decrease expression of MCP-1 mRNA and did not effect its stability. These data demonstrate that doxycycline modulates MCP-1 production and suggest that doxycycline may provide a new anti-inflammatory therapy for chronic lung diseases.