单核细胞趋化蛋白-1与糖尿病肾病

单核细胞趋化蛋白-1(MCP-1)是一种特异性趋化因子，在糖尿病肾病 (diabetic nephropathy，DN)的发生发展中起重要作用。代谢性因素如高糖（HG）、糖基化白蛋白（glycated albumin， Gly-Alb）、氧化应激，蛋白激酶C(protein kinase C，PKC)等和血流动力学因素如肾素-血管紧张素系统（RAS）等均可上调肾小球内皮细胞、系膜细胞 (mesangial cell，MC)、小管上皮细胞（tubulus epithelial cells，TECs）中MCP-1基因和蛋白的表达，使单核/巨噬细胞在肾组织中聚集，通过多种机制引起肾脏损伤。     

Monocyte cytotoxicity during acute kidney graft rejection in rats

Surface antigens, mRNA expression patterns and intravascular accumulation suggested that monocytes might directly participate in acute renal allograft rejection in rats. A flow cytometry-based cytotoxicity assay was used in the present study to analyze the cytotoxic activity of monocytes from the renal and the whole extrapulmonary vasculature of kidney graft recipients (DA to LEW or LEW to LEW) and of untreated animals. The NK-sensitive lymphoma Yac-1 and the NO-sensitive mastocytoma P815 were labeled with FITC and used as target cells. Cellular damage was demonstrated with propidium iodide (PI) or merocyanine 540 (MC 540). On day 4 after allogeneic kidney transplantation the monocyte cytotoxicity towards Yac-1 increased 2-fold in comparison to control animals, whereas cytotoxicity towards P815 cells did not change considerably. PI and MC 540 staining indicated pro-necrotic as well as pro-apoptotic cytotoxic mechanisms. Furthermore, monocytes obviously damaged targets by cytotoxic mechanisms differing from NK cells. In conclusion, monocyte cytotoxicity might be an important effector mechanism in acute renal allograft rejection.     

Monocyte chemoattractant protein-1 is a mediator of acute excitotoxic injury in neonatal rat brain

Monocyte chemoattractant protein-1 is a chemokine with potent monocyte activating and chemotactic effects. Monocyte chemoattractant protein-1 gene and protein expression is rapidly up-regulated in response to a variety of acute and chronic central nervous system disorders. The activation and recruitment of microglia and monocytes into areas of inflammation may play a critical role in the pathogenesis of acute brain injury. Monocyte chemoattractant protein-1 could be a pathophysiologically important mediator of the microglial and monocyte responses in the brain. Using a well-characterized model of acute excitotoxic brain injury in neonatal rats, experiments were designed to evaluate whether monocyte chemoattractant protein-1 plays a role in the progression of tissue damage. Direct co-administration of recombinant monocyte chemoattractant protein-1 with the excitotoxin N-methyl-D-aspartate exacerbated injury, both in the striatum and in the hippocampus, by 55% and 167%, respectively. Complementary experiments to determine the effect of functional inhibition of monocyte chemoattractant protein-1, using an anti-monocyte chemoattractant protein-1-neutralizing antibody, revealed that co-administration of the antibody with N-methyl-D-aspartate attenuated tissue injury in the striatum and hippocampus by 57% and 39%, respectively.Together, these data suggest that monocyte chemoattractant protein-1 is a mediator of acute excitotoxic brain injury in neonatal rats and that inflammatory mechanisms contribute significantly to the pathogenesis of acute neonatal brain injury. Whether chemokines are pathophysiologically relevant mediators of neuronal injury in human neonates remains to be determined.     

Role of macrophage chemoattractant protein-1 in acute inflammation after lung contusion

Lung contusion (LC), commonly observed in patients with thoracic trauma is a leading risk factor for development of acute lung injury/acute respiratory distress syndrome. Previously, we have shown that CC chemokine ligand (CCL)-2, a monotactic chemokine abundant in the lungs, is significantly elevated in LC. This study investigated the nature of protection afforded by CCL-2 in acute lung injury/acute respiratory distress syndrome during LC, using rats and CC chemokine receptor (CCR) 2 knockout (CCR2(-/-)) mice. Rats injected with a polyclonal antibody to CCL-2 showed higher levels of albumin and IL-6 in the bronchoalveolar lavage and myeloperoxidase in the lung tissue after LC. Closed-chest bilateral LC demonstrated CCL-2 localization in alveolar macrophages (AMs) and epithelial cells. Subsequent experiments performed using a murine model of LC showed that the extent of injury, assessed by pulmonary compliance and albumin levels in the bronchoalveolar lavage, was higher in the CCR2(-/-) mice when compared with the wild-type (WT) mice. We also found increased release of IL-1β, IL-6, macrophage inflammatory protein-1, and keratinocyte chemoattractant, lower recruitment of AMs, and higher neutrophil infiltration and phagocytic activity in CCR2(-/-) mice at 24 hours. However, impaired phagocytic activity was observed at 48 hours compared with the WT. Production of CCL-2 and macrophage chemoattractant protein-5 was increased in the absence of CCR2, thus suggesting a negative feedback mechanism of regulation. Isolated AMs in the CCR2(-/-) mice showed a predominant M1 phenotype compared with the predominant M2 phenotype in WT mice. Taken together, the above results show that CCL-2 is functionally important in the down-modulation of injury and inflammation in LC.     

Monocyte chemotactic protein-1 in the follicle of the menstrual and IVF cycle

Ovulation constitutes an inflammatory-like process, with macrophages migrating into the follicle. This study evaluates the production of two macrophage-specific chemokines, monocyte chemotactic protein-1 (MCP-1) and macrophage inflammatory protein-1alpha (MIP-1alpha), in the human follicle at ovulation. Blood samples, follicular fluids and follicular cells were collected during menstrual and IVF cycles. Levels of MCP-1 and MIP-1alpha were measured in follicular fluid, blood plasma and cultured media (granulosa, theca and granulosa-lutein cells [GLCs]). Cells were cultured with or without LH, FSH, interleukin (IL)-1alpha, IL-1beta, tumour necrosis factor (TNF) alpha, progesterone or estradiol. The levels of MCP-1 were markedly higher in follicular fluid as compared with blood plasma in both menstrual and IVF cycles. The difference in MCP-1 levels between follicular fluid and plasma in menstrual cycles increased from the follicular phase (three-fold difference) to the late ovulatory phase (25-fold). Levels of MIP-1alpha were low in plasma and follicular fluid of both menstrual and IVF cycles. Theca cells from follicles of menstrual cycles secreted both MCP-1 and MIP-1alpha under basal conditions, and the secretion was increased by addition of IL-1beta (MCP-1 and MIP-1alpha) and IL-1alpha (MCP-1). GLCs secreted MCP-1 under basal conditions and also MIP-1alpha after IL-1beta stimulation. The macrophage-specific chemokine MCP-1 is highly expressed and is induced by IL-1 in the theca layer of the human follicle at ovulation.     

Monocyte recruitment and expression of monocyte chemoattractant protein-1 are developmentally regulated in remodeling bone in the mouse.

Tooth eruption is defined as the movement of a tooth from its site of development within the alveolar bone to its position of function in the oral cavity. It represents an excellent model to examine osseous metabolism as bone resorption and bone formation occur simultaneously and are spatially separated. Bone resorption occurs in the coronal (occlusal) area, whereas bone formation occurs in the basal area. Monocytes are thought to have a significant role in the regulation of osseous metabolism. The goal of this study was to examine the recruitment of monocytes to bone in C57BL/6J mice that are undergoing developmentally regulated bone remodeling. Monocytes were detected by immunohistochemistry and osteoclasts were counted as bone-associated multi-nucleated, tartrate-resistant acid phosphatase (TRAP)-positive cells. Cell numbers were obtained from histological sections of animals sacrificed daily for 14 days after birth; an image analysis system was used for quantification. The results demonstrated that, immediately after birth, there were relatively few monocytic cells. In the area of bone resorption, the number of monocytes increased with time, reaching peaks at 5 and 9 days, and decreased thereafter. A similar pattern was observed for osteoclasts. In the area of bone formation, there was a time-dependent increase in the number of monocytes. In contrast, the number of osteoclasts in this area was highest at the earliest time points and decreased after day 3. To investigate potential mechanisms for the recruitment of monocytes, expression of monocyte chemoattractant protein (MCP)-1 was assessed. The number of MCP-1-positive cells increased with time and was generally proportional to the recruitment of mononuclear phagocytes. Osteoblasts were the principal bone cell type expressing MCP-1. The results demonstrate that the recruitment of mononuclear cells in the occlusal area is associated with bone resorption. In contrast, recruitment of monocytes in the basal area is associated with bone formation and a decrease in the number of osteoclasts. These results suggest that monocytes have different functional roles in areas of bone formation compared with bone resorption. Furthermore, the expression of MCP-1 is developmentally regulated and may provide a mechanistic basis to explain the recruitment of monocytic cells.     

Monocyte chemoattractant protein-1 promoter -2518 polymorphism and schizophrenia in the Korean population

The purpose of the present study was to investigate the association between the monocyte chemoattractant protein-1 (MCP-1) promoter -2518 polymorphism and schizophrenia. One hundred and twenty-three schizophrenic inpatients and 114 healthy controls participated in this study. Genotyping was performed by polymerase chain reaction-restriction fragment length polymorphism. Genotype and allele distributions in patients with schizophrenia were not significantly different from those of the controls. However, distributions of genotypes and alleles were marginally different when considering subjects with positive and negative symptomatology. The present study therefore calls for further studies on the potential role of the MCP-1 promoter -2518 polymorphism in clinical heterogeneity of schizophrenia.     

Monocyte chemotactic protein-1 production in patients with active pulmonary tuberculosis and tuberculous pleurisy

OBJECTIVE: The role of monocyte chemotactic protein (MCP)-1 in human pulmonary and pleural tuberculosis (TB) was assessed by examining its production in clinical samples from patients with active pulmonary TB and tuberculous pleurisy (TBP). METHODS: Serum was obtained from 26 active pulmonary TB patients [14 early TB (E-TB), and 12 chronic refractory TB (CR-TB)] and 15 healthy tuberculin reactors (HTRs). The monocytes and peripheral blood mononuclear cells (PBMCs) were separated and stimulated with purified protein derivatives (PPD) or the 30-kDa antigen of Mycobacterium tuberculosis. Pleural exudates were isolated from 25 patients with TBP and 24 non-TBP patients [malignancy and congestive heart failure (CHF)]. The MCP-1 levels were measured by enzyme-linked immunosorbent assay (ELISA). RESULTS: In sera, the MCP-1 levels of TB patients were similar to those of HTRs. For monocytes, CR-TB patients spontaneously expressed more MCP-1, compared with HTRs and E-TB patients. In addition, MCP-1 production of PPD- or 30-kDa antigen-stimulated monocytes was significantly elevated in CR-TB patients than that from E-TB. Interestingly, the E-TB patients had significantly depressed MCP-1 production by PBMCs in response to PPD or 30-kDa, compared with HTRs and CR-TB patients. In pleural effusions, MCP-1 levels were significantly higher in patients with TBP than in patients with CHF, but lower than in malignant effusions. CONCLUSIONS: The data suggest that MCP-1 production is not uniquely elevated systemically in TB patients, although MCP-1 production might be elevated by monocytes in the chronic phase of TB or with a local pleural infection.     

Identification and characterization of cells infiltrating the graft and aqueous humour in rat corneal allograft rejection

In a rat model of corneal transplantation, Fischer 344 (RT1^lv1) rats received orthotopic corneal isografts or Wistar-Furth (RT1^u) donor allografts. Rejection was observed in 25 of 26 allograft recipients, at a median time of 18 days, with all isografts surviving > 100 days. Flow cytometric analysis of aqueous humour identified cellular infiltration of the aqueous at the time of allograft rejection, in contrast to the acellular aqueous found in isografts at corresponding times following transplantation. A higher proportion of CD8⁺ than CD4⁺ cells was found at days 1–3 following rejection, whereas there was a higher proportion of CD4⁺ cells at days 5–8. No changes in peripheral blood T cell subsets were found at the time of rejection. Immunohistochemical analysis of cells infiltrating recipient iris and grafted cornea undertaken at days 1–2, 4 and 7–10 following onset of rejection, demonstrated inflammatory cells in the graft epithelium, stroma and aggregated on the endothelium. Large numbers of macrophages, T cells (CD4⁺ > CD8⁺ at all time points), natural killer (NK) cells and neutrophils were detected in graft tissue at days 1–2 and 4, diminishing after that time. Most infiltrating cells expressed MHC class II antigen, and a smaller number expressed IL-2R. Expression of the co-stimulatory marker B7 was identified in a few cells at day 4 in the region of the graft-host wound. The immune response in graft rejection was characterized at day 4 also by expression of intercellular adhesion molecule-1 (ICAM-1) on endothelial cells of iris and corneal vessels, demonstration of interferon-gamma on mononuclear cells in the peripheral (recipient) cornea, and tumour necrosis factor-alpha on aggregated mononuclear cells on the graft, but not recipient, endothelium. Only sparse cellular infiltrates were found in isograft controls, with inflammation located at the graft-host wound. These findings suggest that inflammatory cells reach a corneal allograft by two routes—from vessels in the peripheral recipient cornea, and from vessels in the recipient iris via the aqueous humour. Different aqueous and intragraft T cell subset proportions were seen early in rejection, although a preponderance of CD4⁺ cells was found in both aqueous and graft at later times.     

Induction of vascular adhesion protein-1 during liver allograft rejection and concomitant cytomegalovirus infection in rats

Vascular adhesion protein-1 (VAP-1) is an adhesion molecule controlling lymphocyte recirculation through high endothelial venules of the lymph nodes. It has also been shown to be induced and to mediate lymphocyte adhesion at sites of inflammation. We studied the expression of VAP-1 and two other inducible adhesion molecules ICAM-1 and VCAM-1 in our experimental model of rat liver allograft rejection and, in addition, the effect of concomitant rat cytomegalovirus (RCMV) infection on this expression. Expression of VAP-1, ICAM-1, and VCAM-1 was studied in rat liver allografts with or without RCMV infection, isografts, and normal rat liver. Immunoperoxidase technique and monoclonal antibodies including a novel anti-VAP-1 reagent were used. VAP-1 expression was induced by acute rejection in sinusoids, hepatocytes, and also in bile ducts, when compared to the isografts or normal liver, where only blood vessels were consistently positive. Sinusoidal and hepatocyte expression of VAP-1 was prolonged by the presence of RCMV. ICAM-1 and VCAM-1 expression was also induced by acute rejection. However, RCMV increased sinusoidal VCAM-1 expression compared to uninfected grafts. The present experimental study shows that VAP-1 is up-regulated in acute rejection of liver allografts, and that this up-regulation is prolonged by RCMV infection.     

Monocyte chemotactic protein-1 provokes mast cell aggregation and [3H]5HT release.

Monocyte chemotactic protein-1 (MCP-1) and MCP-3, the most active and representative compounds of the CC chemokine family, are proinflammatory cytokines that attract and activate specific types of leucocytes. We have used highly purified isolated rat peritoneal mast cells (RPMC) cultured for different lengths of time with and without MCP-1 (200, 100, 50 and 25 nM). Our data clearly show that MCP-1 (200 nM) causes a marked release of [3H]serotonin ([3H]5HT and histamine, which reach a peak at 40 min of incubation (56.6 +/- 5.3 and 34.7 +/- 6 above the control, respectively). In dose-response experiments, MCP-1 (200, 100, 50, 25, 12.5, 6.25 and 3.12 nM) provoked a dose-dependent release of [3H]5HT and histamine from RPMC, which was maximum at 200 nM. After preparation of the histidine decarboxylase (HDC) probe, a Northern blot analysis was determined for HDC mRNA. After 4 hr, steady-state levels of HDC mRNA were induced in a dose-dependent manner by MCP-1 (200-25 nM), compared to the controls. However, MCP-1 failed to prime RPMC in [3H]5HT and histamine release when C48/80 (0.05 micrograms/ml) or anti-IgE was used. In contrast, murine interleukin-3 (IL-3) in combination with MCP-1 (200 and 100 nM) provoked a greater release of histamine and [3H]5HT than the compounds alone. Moreover, RPMC treated with MCP-1 (200 nM) showed, under light microscopy (20x), greater clump formation, a phenomenon absent in the controls (untreated cells). The electron microscope studies revealed that treatment with MCP-1 (200 nM) promoted binding of RPMC and clearly demonstrated a communication between the cytoplasms of adjacent mast cells. Our report describes additional biological activities for MCP-1, suggesting for the first time that this human monocyte chemoattractant plays a fundamental role in histamine and serotonin release and cell aggregation in rat peritoneal mast cells.     

Monocyte chemotactic protein-1 is a proinflammatory chemokine in rat skin injection sites and chemoattracts basophilic granular cells

Chemokines may control mast cell infiltrates found in many inflammatory diseases. These cells act through at least two main functions: migration and degranulation. Here we show that human recombinant monocyte chemotactic protein (MCP)-1 (10 ng/50 microliters) induces, after 4 h, an inflammatory vascular permeability and cellular extravasation reaction, determined by Evan's blue dye (1% in saline) injected into the tail vein of the rat, when injected intradermally in the rat skin. The blue color accumulating at the sites of injection provides evidence of vascular permeability and cellular extravasation. The colored areas of the skin were then enucleated and immersed in a fixative solution. Slides were prepared with sections of tissue colored with toluldine blue and analyzed under an optical microscope. A significant number of basophilic cells migrated to the injected area where MCP-1 (10 ng/50 microliters) was used compared to the control PBS treatment. Cell recruitment was slightly less than N-formyl-methionine- leucyl-phenylalanine (used at 10(-6) M/50 microliters). Electron microscopy studies confirmed the presence of basophilic granular cells where MCP-1 was intradermally injected. After preparation of a histidine decarboxylase (HDC) probe, a Northern blot analysis was determined for HDC mRNA in the enucleated tissue injected with MCP-1 (10 ng/50 microliters). Steady-state levels of HDC mRNA levels were induced after 4 h. These results were confirmed by the higher amount of histamine release, compared to the control PBS, in the enucleated tissue from the MCP-1 injection sites. Our results suggest that MCP-1 could play a significant role in diseases characterized by basophilic cell accumulation and migration to sites of tissue damage. Moreover, we show for the first time that MCP-1 is a pro-inflammatory chemokine that induces basophilic cell migration in rat skin injection sites.      

Monocyte chemotactic protein-1, -2, and -3 are distinctively expressed in portal tracts and granulomata in primary biliary cirrhosis: implications for pathogenesis

The monocyte chemotactic proteins (MCPs) form a distinct structurally related subclass of C-C chemokines. MCPs select specific target cells due to binding to a distinct set of chemokine receptors and because of their effects on monocytes, and may participate in the process of granuloma formation during bacterial and/or mycobacterial infections. The aetiology of primary biliary cirrhosis (PBC) is still unclear, although bacterial infection and autoimmune processes have been implicated. In this study, the expression of three of the most potent monocyte chemoattractants, MCP-1, -2, and -3, was examined in patients with PBC and the data were compared with results for other liver diseases including primary sclerosing cholangitis (PSC), chronic viral hepatitis C, hepatic sarcoidosis, and normal liver. MCP-1 was expressed mainly in biliary epithelial cells of all liver specimens, irrespective of the cause of disease. Some mononuclear leukocytes in the portal tract expressed MCP-1 in all the disease groups examined and there were no significant differences in frequency between these groups. In contrast, more than 80% of PBC livers showed MCP-2- and MCP-3-positive mononuclear leukocyte infiltration in portal tracts, particularly around the bile ducts, whereas such cells were far less frequent in the other disease groups or in normal livers. Epithelioid granulomata of PBC patients contained MCP-2- and MCP-3-positive cells at their edge. In double staining experiments, more than 60% of the MCP-positive mononuclear cells co-expressed CD68, suggesting that a proportion of MCP-2- and MCP-3-positive cells are derived from monocytes. These monocytes expressing MCP-2 and MCP-3 may be responsible for the chemotactic activity of more monocytes. Such an expression pattern of MCP-1, -2 and -3 in portal tracts seems to be distinctive for PBC. This pattern underlines the importance of MCP-1, -2, and -3 in the recruitment of monocytes and possibly T lymphocytes into portal tracts, around the injured bile ducts, and into epithelioid granulomata in PBC. The data further implicate bacterial materials derived from bile in the overall pathogenesis of PBC.     

Peripheral blood and intrarenal phagocytic chemiluminescence during acute kidney graft rejection

During organ graft rejection, soluble mediators of inflammation are released into the polymorphs (PMNs) and monocytes recruited from the blood. One functional capacity of polymorphs and monocytes/macrophages is the production of cytotoxic activated oxygen species upon stimulation, which may contribute to the rejection process. Nothing is known about the influence of allograft rejection on this inflammatory cell property. Chemiluminescence (CL) allows measurement of respiratory burst capacity in small cell samples. Zymosan-induced and luminol-amplified CL of diluted whole blood, separated PMNs, and mononuclear cells from peripheral venous blood, as well as of intragraft phagocytes was measured after allogeneic and autologous kidney transplantation in untreated dogs, CL of separated PMNs, mononuclear cells, and intragraft phagocytes was significantly elevated during allograft rejection. In autologous kidneys transplanted to recipients of allografts, CL was also increased in the autologous grafts during rejection of the allogeneic ones, indicating a systemic alteration in phagocyte function.     

Monocytes in the rat: Phenotype and function during acute allograft rejection

Summary: Cells of the monocyte/macrophage system originate from the bone marrow, reach the organs via the blood, immigrate through post-capillary venules and further differentiate into organ-specific tissue macrophages. In rats and other species, activated monocytes/macrophages aggravate autoimmune reactions, rejection of non-vascularized allografts and chronic allograft rejection. It is very likely that they also contribute to acute allograft destruction. So far it has been impossible to distinguish the function of monocytes from that of macrophages, because cell phenotypes and their alterations upon activation are ill-defined. We have thus begun to characterize the ex vivo phenotype and function of rat monocytes in the normal state and during renal allograft rejection. Monocytes are recovered from both the central and the marginal blood pool by perfusing either the recipient's circulation or the allograft vasculature. Rat monocytes have a unique surface phenotype. During allograft rejection or after infusion of interferon-γ they up-regulate class II MHC molecules, CD161 (NKR-P1A), CD62L and CD8, while CD4 and CD43 are down-modulated. Activated perfusate monocytes exert increased in vitro cytotoxicity against tumour targets, which differs from that of NK cells. We speculate that activated monocytes contribute to kidney allograft destruction by directly damaging endothelial cells or by promoting intravascular coagulation.