Expression of macrophage inflammatory protein-1α in Kupffer cells following liver ischemia or reperfusion injury in rats

AIM: To explore the expression of macrophage inflammatory protein-1alpha (MIP-1alpha) in Kupffer cells (KCs) following liver ischemia/reperfusion injury IRI in rats. METHODS: Forty male SD rats were divided randomly into five groups. A model of partial warm ischemia/reperfusion injury in the rat liver was established. KCs were isolated and incubated one hour, six hours, 12 h, and 24 h after the reperfusion. Tumor necrosis factor alpha (TNF-alpha) and interleukin-1beta (IL-1beta) in the supernatants were measured by ELISA. MIP-1alpha in KCs was detected by immunocytochemical and RT-PCR. RESULTS: No or few MIP-1alpha protein and mRNA were expressed in the KCs of the control group. Its expression in the IRI group had a significant increase after the reperfusion (P < 0.05), which was contrary to the control group. CONCLUSION: The active behavior of the MIP-1alpha gene in KCs following liver ischemia/reperfusion injury is assumed to be one of the major causes for the hepatic ischemia/reperfusion injury.     

Chemokine and Cell Adhesion Molecule mRNA Expression and Neutrophil Infiltration in Lipopolysaccharide-Induced Hepatitis in Ethanol-Fed Rats

Neutrophil infiltration is a feature of alcoholic hepatitis (AH), and although the mechanism by which this occurs is unclear, it may involve a chemotactic gradient. We used lipopolysaccharide (LPS) to induce, in ethanol-fed rats, liver damage similar to that seen in AH. To our knowledge, this study is the first to examine the effect of ethanol on LPS-stimulated chemokine mRNA expression in this model. Hepatic cytokine-induced neutrophil chemoattractant (CINC)-1, CINC-2, monocyte chemoattractant protein-1 (MCP-l), macrophage inflammatory protein (MIP)-1 β, MIP-2, and eotaxin mRNA levels were elevated 1 to 3 hr post-LPS in both groups. Maximal expression of MIP-2 and MCP-1 mRNA was higher in ethanol-fed rats 1 hr post-LPS, whereas CINC-2 mRNA expression was elevated above controls at 12 to 24 hr. Hepatic intercellular adhesion molecule-1 and vascular cell adhesion molecule-1 mRNA levels were elevated in both groups at 1 hr, whereas L-selectin expression in ethanol-fed rats was elevated above controls at 12 to 24 hr. Hepatic neutrophil infiltration was highest during maximal hepatocyte necrosis. These data suggest that cell adhesion molecules, in conjunction with elevated cytokines and the subsequently induced chemokines, may assist in the formation of a chemotactic gradient within the liver, causing the neutrophil infiltration seen both in this model and possibly in AH.     

Granulocyte macrophage colony-stimulating factor and interleukin-3 regulate chemokine and chemokine receptor expression in bone marrow macrophages

The beta-chemokine macrophage inflammatory protein-1 alpha (MIP-1alpha) and its associated receptors are involved in the regulation of pro-inflammatory and haemopoietic processes. This study was designed to investigate regulation of expression MIP-1alpha and its receptors by other haemopoietic cytokines. Murine bone marrow macrophages (BMM) were treated with or without GM-CSF or IL-3 and expression of MIP-1alpha, other chemokines and their receptors examined by Northern blotting. Receptor levels were also examined using Scatchard analysis and functional tests. Treatment of BMM with GM-CSF revealed a striking increase in MIP-1alpha mRNA levels, relative to untreated cells with a corresponding increase in MIP-1alpha protein. A similar increase in mRNA levels was found when BMM were treated with IL-3. An increase in the expression of three other beta-chemokines namely MIP-1beta, MCP-1 and MCP-3, was also found following treatment with GM-CSF or IL-3. We have additionally examined the expression of the known beta-chemokine receptors in BMM and observed an increase in CCR1 mRNA levels following treatment with GM-CSF and IL-3, but no change was seen in the level of CCR5 expression. The increase in CCR1 expression was reflected in an increase in the number of cell surface receptors for MIP-1alpha on the GM-CSF treated BMM and in an enhanced response of the GM-CSF treated BMM to CCR1 ligands. These data suggest that GM-CSF and IL-3 may be involved in mechanisms regulating expression levels of MIP-1alpha and its receptors.     

Expression of chemokines and matrix metalloproteinases in early rheumatoid arthritis

OBJECTIVE: To compare macrophage infiltration and expression of chemokines and matrix metalloproteinases (MMPs) in synovial tissue between patients with early and long-standing rheumatoid arthritis (RA). METHODS: Knee synovial biopsies were taken from 22 patients with early (<1 yr) and 22 patients with long-standing (>5 yr) RA and immunostained with antibodies specific for CD68; macrophage inflammatory protein (MIP)-1alpha and monocyte chemoattractant protein (MCP)-1; MMP-1 and -3 and the tissue inhibitors of metalloproteinases (TIMP)-l and -2. Immunostaining was quantified using a colour video image analysis system. RESULTS: CD68+ macrophage infiltration and the expression of MIP-1alpha, MCP-1, MMP-1, MMP-3, TIMP-1, and TIMP-2 were observed in synovial tissue of patients with early RA. In long-standing RA, there was a further increase in CD68+ macrophage infiltration and MIP-1alpha expression in the synovial lining layer. CD68 expression correlated with MIP-1alpha (R=0.39, P=0.01), but not with MCP-1 expression. CONCLUSION: Macrophage accumulation, and the expression of chemokines and MMPs in synovial tissue occur in early RA. Targeting chemokines which play a role in the migration of macrophages into the joints may be of therapeutic benefit in RA patients.     

Expression of macrophage inflammatory protein-1α in Kupffer cells following liver ischemia or reperfusion injury in rats

AIM: To explore the expression of macrophage inflammatory protein-1α (MIP-1α) in Kupffer cells (KCs)following liver ischemia/reperfusion injury IRI in rats.METHODS: Forty male SD rats were divided randomly into five groups. A model of partial warm ischemia/reperfusion injury in the rat liver was established. KCs were isolated and incubated one hour, six hours, 12 h,and 24 h after the reperfusion. Tumor necrosis factor alpha (TNF-α) and interleukin-1beta (IL-1β) in the supernatants were measured by ELISA. MIP-1α in KCs was detected by immunocytochemical and RT-PCR.RESULTS: No or few MIP-1α protein and mRNA were expressed in the KCs of the control group. Its expression in the IRI group had a significant increase after the reperfusion (P ＜ 0.05), which was contrary to the control group.CONCLUSION: The active behavior of the MIP-1α gene in KCs following liver ischemia/reperfusion injury is assumed to be one of the major causes for the hepatic ischemia/reperfusion injury.     

Association of the MCP-1 gene polymorphism A-2518G with carpal-tunnel syndrome in hemodialysis patients.

Carpal-tunnel syndrome (CTS) in long-term hemodialysis patients is caused by the deposition of amyloid as well as by the local inflammatory process. The recruitment of monocytes/macrophages in the tenosynovium, promoted by chemokines such as monocyte chemoattractant protein-1 (MCP-1) and macrophage inflammatory protein-1alpha (MIP-1alpha), is thought to play an important role in CTS development. The genetic polymorphism of these chemokines has been identified and their clinical function has been partly revealed We attempted to analyze the relationship between these polymorphisms and their susceptibility to CTS. The subjects of this study were 366 patients who underwent hemodialysis. Ninety-five patients received surgery for CTS. No significant difference was observed in the genotype distributions of MCP-1 or MIP-1alpha between patients who received CTS surgery and those that did not. However, with the use of a logistic regression model, the MCP-1 GG genotype was identified as a risk factor for the development of CTS, in addition to the duration and the age of initiation of dialysis, as confirmed by a Cox proportional hazards model. In conclusion, homozygosity for G at -2518 in the MCP-1 gene might be a candidate for the genetic marker of CTS development in Japanese hemodialysis patients.     

Increased expression of cytokines and adhesion molecules in rat chronic esophagitis

BACKGROUND/AIMS: Cytokines and adhesion molecules regulate many inflammatory processes in several gastrointestinal diseases. The dynamics of cytokines and adhesion molecules in reflux esophagitis are unknown in detail. We examined the expression and dynamics of interleukin-1beta (IL-1beta), tumor necrosis factor-alpha (TNF-alpha), monocyte chemotactic protein-1 (MCP-1), macrophage inflammatory protein-1alpha (MIP-1alpha), MIP-2, GRO/cytokine-induced neutrophil chemoattractant-2alpha (CINC-2alpha), intercellular adhesion molecule-1 (ICAM-1), leukocyte function-associated antigen 1 (LFA-1; CD11a/CD18), and Mac-1 (CD11b/CD18) in rat chronic reflux esophagitis. METHODS: Chronic acid reflux esophagitis was induced in Wistar rats by ligating the transitional region between the forestomach and the glandular portion and wrapping the duodenum near the pylorus with a small piece of an 18-Fr Nélaton catheter. Rats were killed 3 or 21 days after operation. The levels of mRNA expression of cytokines and ICAM-1 were determined by real-time quantitative RT-PCR. Localization of adhesion molecules and cytokines was investigated by immunohistochemical staining, and numbers of LFA-1- or Mac-1-positive cells were quantified. RESULTS: IL-1beta, TNF-alpha, MCP-1, MIP-1alpha, MIP-2, CINC-2alpha, and ICAM-1 mRNA expression was significantly increased in esophageal lesions compared with normal esophagus. There were few these cytokines- or adhesion molecule-positive cells in normal esophagus. In regions of esophagitis, numerous inflammatory leukocytes in lamina propria and the submucosal layer exhibited positive reactions for these cytokines and endothelial cells were intensely stained for ICAM-1. Numbers of LFA-1- and Mac-1-positive cells were significantly increased in rat chronic esophagitis. Treatment with rabeprazole almost completely inhibited development of chronic acid reflux esophagitis and significantly decreased expression of cytokines and ICAM-1 mRNA in esophageal tissue compared with control. CONCLUSION: Cytokines and adhesion molecules play important roles in the pathogenesis of chronic reflux esophagitis in this rat model.     

Role of macrophage infiltration in the orbital fat of patients with Graves' ophthalmopathy

Objective  Infiltration of the retro-ocular space by inflammatory cells, accumulation of glycosaminoglycans, and the overabundance of orbital adipose tissue are characteristic findings in Graves' ophthalmopathy (GO). The cause of macrophage infiltration in the orbital adipose tissue of patients with GO remains to be elucidated.
Design  Immunohistochemistry of orbital adipose tissues with anti-CD68 was used for determining macrophage infiltration pattern and cell counts. Quantitative real-time PCR was used for analysing mRNA expression. Correlation of macrophage infiltration with the duration of GO and mRNA expression were also determined.
Patients  Fifteen subjects with GO who underwent orbital decompression were recruited. Six patients without thyroid history who underwent elective orbital surgery were enrolled as controls.
Measurements  Histological distribution of macrophages, macrophage cell counts, CD68 and monocyte chemoattractant protein-1 (MCP-1) mRNA levels, and duration of GO.
Results  We demonstrated that macrophage infiltration in orbital fat from patients with GO was higher than controls ( P  = 0·005). The infiltration of macrophages was located primarily around blood vessels and between mature adipocytes. Macrophage infiltration did not attenuate in GO of long duration. We also found that the expression of MCP-1 was higher in GO orbital fat than that in the orbital fat of controls ( P =  0·047) and the infiltration of macrophages in adipose tissue from patients with GO was positively correlated with expression of MCP-1 mRNA ( r  = 0·546, P  = 0·035).
Conclusion  Macrophage infiltration may play an important role in the pathogenesis of GO via over-expression of MCP-1.     

CC chemokine concentrations increase in respiratory distress syndrome and correlate with development of bronchopulmonary dysplasia

Inflammation is one of the primary processes underlying respiratory distress syndrome (RDS) and its evolution into bronchopulmonary dysplasia (BPD). Recruitment and subsequent activation of macrophages in the lung are mediated by CC chemokines. The role of CC chemokines has not been extensively studied in the course of RDS. Serial tracheal aspirates (TA) were obtained from 56 mechanically ventilated infants with birth weights less than 1,500 g during intervals in the first 21 days of life. Tracheal aspirate concentrations of monocyte chemoattractant proteins-1,2,3 (MCP-1,2,3) and macrophage inflammatory proteins-1alpha and -1beta (MIP-1alpha, MIP-1beta) were determined by enzyme-linked immunosorbent assay (ELISA). Tracheal aspirate concentrations of MCP-1, MCP-2, MCP-3, and MIP-1beta increased during the first week of life in infants with RDS, whereas MIP-1alpha concentrations did not increase appreciably. Increased TA cytokine concentrations were associated with the development of BPD. Maximal TA concentrations of MCP-1, MCP-2, MCP-3, MIP-1alpha, and MIP-1beta were significantly higher in infants who were oxygen-dependent at 28 postnatal days compared to infant who were not. Similarly, maximal TA MCP-1, MCP-2, and MCP-3 but not MIP-1alpha and MIP-1beta concentrations were significantly higher in infants who were oxygen-dependent at 36 weeks of postconceptional age (PCA) than those who were not oxygen-dependent at 36 weeks PCA. Histologic chorioamnionitis and isolation of Ureaplasma urealyticum from the airways were associated with higher maximal TA concentrations of MIP-1alpha and MIP-1beta. Pulmonary hemorrhage was associated with increased maximal concentrations of MCP-1, MCP-2, and MCP-3. These data suggest a role for CC chemokines in the development of BPD in the newborn infant.     

Preventive effect of cyclosporin A on experimentally induced acute liver injury in rats

Abstract: We examined the effect of cyclosporin A (CsA) on the pathogenesis of acute experimental liver injury in rats induced by injection of heat-killed Propionibacterium acnes (P. acnes) and subsequent injection of lipopolysaccharide (LPS). Pretreatment with CsA significantly reduced serum alanine aminotransferase (ALT), serum tumor necrosis factor-α (TNF-α) production, without changing the TNF-α mRNA level in the liver, and plasma interferon-γ (IFN-γ), following LPS injection in this model. Twenty-four-hour mortality was also markedly improved, from 100% in the P. acnes plus LPS group to 0% in the CsA-pretreated group. Although direct addition of CsA to isolated hepatic macrophages from P. acnes-pretreated rats did not prevent the production of TNF-α and active oxygen species, isolated hepatic macrophages from P. acnes plus CsA-pretreated rats significantly reduced their production in response to the addition of LPS. These results suggest that CsA protects against P. acnes plus LPS-induced acute liver injury, not by direct inhibition of hepatic macrophage activation, but by indirect prevention of hepatic macrophage activation, presumably related to the reduction in plasma IFN-γ levels.     

Chemokine and cytokine expression in murine intestinal epithelium following Nippostrongylus brasiliensis infection

Infection of mice with the nematode parasite Nippostrongylus brasiliensis results in a well characterized intestinal mastocytosis with intraepithelial migration of mucosal mast cells (MMC). The molecules mediating this response are unknown. We examined expression of several putative mast cell chemoattractants in intestinal epithelium following N. brasiliensis infection. Expression of the chemokines monocyte chemoattractant protein-1 (MCP-1), macrophage inflammatory protein-1 alpha (MIP-1alpha), RANTES (regulated on activation normal T-cell expressed and secreted), fractalkine, and thymocyte expressed chemokine (TECK); and the cytokines stem cell factor (SCF) and transforming growth factor beta1 (TGFbeta1), was constitutive and no alteration was detected following infection. MCP-1 expression was also constitutive but at much lower levels and increased expression was detected on days 7 and 14 postinfection. Expression of MCP-1 in whole jejunum was at much higher levels than in epithelium. Constitutive expression of MCP-1, MIP-1alpha and TGFbeta1 was also detected in cultured bone marrow-derived homologues of MMC. In an intestinal epithelial cell line (CMT-93), there was constitutive expression of SCF, TGFalpha1, fractalkine and MCP-1. The results show that, in vivo, epithelium is a potentially important source of mast cell chemoattractants.     

Increased macrophage chemoattractant protein-1 in cerebrospinal fluid precedes and predicts simian immunodeficiency virus encephalitis

Macrophage chemoattractant protein-1 (MCP-1) may be a key trigger for the influx of macrophages into the brain in human immunodeficiency virus (HIV) encephalitis. In this study, simian immunodeficiency virus-infected macaques that developed moderate-to-severe encephalitis had significantly higher MCP-1 levels in cerebrospinal fluid (CSF) than in plasma as early as 28 days after inoculation, which was before the development of brain lesions. In contrast, CSF:plasma MCP-1 ratios remained constant at preinoculation levels in macaques that developed minimal or no encephalitis. Abundant MCP-1 protein and mRNA were detected in both macrophages and astrocytes in the brain. Macaques with increased MCP-1 in CSF had significantly greater expression of markers of macrophage and microglia activation and infiltration (CD68; P= .003) and astrocyte activation (glial fibrillary acidic protein; P= .019 and P= .031 in white and gray matter, respectively). The results suggest that the CSF:plasma MCP-1 ratio may be a valuable prognostic marker for the development of HIV-induced central nervous system disease.     

Effects of intraarticular glucocorticoids on macrophage infiltration and mediators of joint damage in osteoarthritis synovial membranes: findings in a double-blind, placebo-controlled study

OBJECTIVE: To investigate the effects of intraarticular glucocorticoid treatment on macrophage infiltration, the expression of the chemokines monocyte chemoattractant protein 1 (MCP-1) and macrophage inflammatory protein 1alpha (MIP-1alpha), and the expression of matrix metalloproteinases 1 and 3 (MMPs 1 and 3) and their inhibitors, the tissue inhibitors of metalloproteinases 1 and 2 (TIMPs 1 and 2), in osteoarthritis (OA) synovial membranes. METHODS: Forty patients underwent arthroscopic biopsy before and 1 month after intraarticular injection of glucocorticoids. Twenty-one patients received 120 mg of methylprednisolone acetate (Depo-Medrol; Upjohn, Kalamazoo, MI), and 20 patients received placebo (1 patient received placebo in 1 knee and methylprednisolone acetate in the other). Immunoperoxidase staining for the expression of CD68, MCP-1, MIP-1alpha, MMP-1, MMP-3, TIMP-1, and TIMP-2 was performed, and the immunostaining was quantified by color video image analysis. RESULTS: CD68, MCP-1, MIP-1alpha, MMP-1, MMP-3, TIMP-1, and TIMP-2 immunostaining was observed in all synovial membranes. Intraarticular glucocorticoid treatment was associated with a small (30%) but statistically significant (P = 0.048) reduction in CD68+ macrophage staining in the synovial lining layer, but there was no change in the CD68 expression in the synovial sublining layer. No significant differences were observed for MCP-1, MIP-1alpha, MMP-1, MMP-3, TIMP-1, and TIMP-2 immunostaining in the synovial lining or sublining layers. CONCLUSION: Intraarticular glucocorticoids may reduce CD68+ macrophage infiltration into the synovial lining layer, but not the expression of MCP-1, MIP-1alpha, MMP-1, MMP-3, TIMP-1, and TIMP-2 in the synovial membrane, in patients with OA.     

Macrophage inflammatory protein-1alpha mediates matrix metalloproteinase-9 enhancement in human adherent monocytes fed with malarial pigment

ObjectiveTo investigate the role of macrophage inflammatory protein-1alpha (MIP-1alpha) in the detrimental enhancement of matrix metalloproteinase-9 (MMP-9) expression, release and activity induced by phagocytosis of malarial pigment (haemozoin, HZ) in human monocytes.MethodsHuman adherent monocytes were unfed/fed with native HZ for 2 h. After 24 hours, MIP-1alpha production was evaluated by ELISA in cell supernatants. Alternatively, HZ-unfed/fed monocytes were treated in presence/absence of anti-human MIP-1alpha blocking antibodies or recombinant human MIP-1alpha for 15 h (RNA studies) or 24 h (protein studies); therefore, MMP-9 mRNA expression was evaluated in cell lysates by Real Time RT-PCR, whereas proMMP-9 and active MMP-9 protein release were measured in cell supernatants by Western blotting and gelatin zymography.ResultsPhagocytosis of HZ by human monocytes increased production of MIP-1 alpha, mRNA expression of MMP-9 and protein release of proMMP-9 and active MMP-9. All the HZ-enhancing effects on MMP-9 were abrogated by anti-human MIP-1alpha blocking antibodies and mimicked by recombinant human MIP-1alpha.ConclusionsThe present work suggests a role for MIP-1alpha in the HZ-dependent enhancement of MMP-9 expression, release and activity observed in human monocytes, highlighting new detrimental effects of HZ-triggered proinflammatory response by phagocytic cells in falciparum malaria.     

Role of adhesion molecules in the development of massive hepatic necrosis in rats

Massive hepatic necrosis develops after endotoxin administration in rats pretreated with heat-killed Propionibacterium acnes as a result of microcirculatory disturbance caused by endothelial cell destruction by activated macrophages in the hepatic sinusoids. Immunohistochemical hepatic expression of intercellular adhesion molecule-1 (ICAM-1) and lymphocyte function-associated antigen 1 alpha (LFA-1 alpha) and the effect of monoclonal antibodies against both adhesion molecules on liver necrosis provoked after endotoxin administration was studied in these rats. There were increased stains of ICAM-1 in endothelial cells and LFA-1 alpha in macrophages in the hepatic sinusoids in Propionibacterium acnes-pretreated rats compared with normal rats. Such stains were further increased soon after endotoxin administration, followed by development of hepatic necrosis. Monoclonal antibodies against both adhesion molecules significantly attenuated the extent of liver injury compared with controls, without affecting the infiltration and activation of hepatic macrophages. Polyclonal antibodies against polymorphonuclear leukocytes eradicated circulating neutrophils, but did not change such liver injury, although gum arabic, which suppressed macrophage activation, attenuated the extent of liver injury. Thus, adhesion between endothelial cells and activated macrophages in the hepatic sinusoids via ICAM-1 and LFA-1 alpha is essential for the initiation of massive hepatic necrosis of this type. Contribution of neutrophils seems less likely. (Hepatology 1996 Feb;23(2):320-8)     

Expression and function of CXC and CC chemokines in human malignant liver tumors: a role for human monokine induced by gamma-interferon in lymphocyte recruitment to hepatocellular carcinoma.

Chemotactic cytokines (chemokines) play an important role in the recruitment of lymphocytes to tissue by regulating cellular adhesion and transendothelial migration. This study examined the expression and function of CXC (human monokine induced by gamma-interferon [HuMig], interleukin-8 [IL-8], and interferon-inducible protein-10 [IP-10]) and CC (macrophage inflammatory protein-1alpha [MIP-1alpha], MIP-1beta, regulated upon activation normal T lymphocyte expressed and secreted (RANTES), and macrophage chemoattractant protein-1 [MCP-1]) chemokines and their respective receptors on lymphocytes infiltrating human liver tumors. Chemokine and chemokine receptor expression was assessed by immunohistochemistry, flow cytometry, in situ hybridization and ribonuclease (RNAse) protection assays and function by in vitro chemotaxis of tumor-derived lymphocytes to purified chemokines and to HepG2 tumor cell culture supernatants. Tumor-derived lymphocytes showed strong chemotactic responses to both CC and CXC chemokines in vitro and expressed high levels of CXCR3 (HuMig and IP-10 receptor) and CCR5 (RANTES, MIP-1alpha, and MIP-1beta receptor). Expansion of tumor-derived lymphocytes in recombinant IL-2 increased expression of CXCR3. The corresponding chemokines were detected on vascular endothelium (HuMig, IL-8, MIP-1alpha, and MIP-1beta) and sinusoidal endothelium (HuMig, MIP-1alpha, MIP-1beta) in hepatocellular carcinoma. In vitro, HepG2 cells secreted functional chemotactic factors for tumor-derived lymphocytes that could be inhibited using anti-CCR5 or anti-CXCR3 monoclonal antibodies (MoAbs). Thus, lymphocytes infiltrating human liver tumors express receptors for and respond to both CXC and CC chemokines. The relevant chemokine ligands are expressed in hepatocellular carcinoma (HCC), particularly HuMig, which was strongly expressed by tumor endothelium, suggesting that they play a role in lymphocyte recruitment to these tumors in vivo. The ability of HepG2 cells to secrete lymphocyte chemotactic factors in vitro suggests that the tumor contributes to lymphocyte recruitment in vivo.     

Activated leucocytes express and secrete macrophage inflammatory protein-1alpha upon interaction with synovial fibroblasts of rheumatoid arthritis via a beta2-integrin/ICAM-1 mechanism

OBJECTIVE: To examine the expression and regulation of chemotactic factor, macrophage inflammatory protein-1alpha (MIP-1alpha) by fibroblast-like synoviocytes (FLS), monocytes and polymorphonuclear neutrophils (PMN) isolated from the synovial fluid (SF) of rheumatoid arthritis (RA) patients. METHODS: Monocytes or PMN obtained from RA SF were co-cultured with unstimulated semiconfluent RA FLS. Culture supernatants were assayed for MIP-1alpha by enzyme-linked immunosorbent assay. The expression of MIP-1alpha mRNA and protein was also determined by Northern blot analyss and immunohistochemistry respectively. RESULTS: Interaction of activated leucocytes with FLS synergistically increased MIP-1alpha expression and secretion via a mechanism mediated by beta2-integrin/ intercellular adhesion molecule 1. CONCLUSION: MIP-1alpha expression within inflamed joints appears to be regulated not only by inflammatory cytokines but also by the physical interaction of activated leucocytes and FLS, and plays a crucial role in the progression and maintenance of RA synovitis.     

Role of macrophage inflammatory protein-1alpha (MIP-1alpha) in macrophage homing in the spleen and heart pathology during experimental infection with Trypanosoma cruzi

We investigated in vivo the effect of macrophage inflammatory protein-1alpha (MIP-1alpha) inhibition upon the cellular recruitment into tissue damage sites and spleen histology in mice acutely infected with Trypanosoma cruzi. Histopathological studies of spleen sections revealed a 68% decrease in macrophage/monocyte infiltration as a result of MIP-1alpha neutralisation. Moreover, a reduction in the number of plasma cells and immunoblasts was observed. However, antibody (Ab)-mediated blocking of MIP-1alpha failed to modify tissue parasite levels. Examination of myocardial sections showed an increase in inflammatory lesions in mice treated with anti-MIP-1alpha Ab. There was also an increasing trend in the number of amastigote nests in the myocardium of anti-MIP-1alpha-treated mice compared with controls. Administration of anti-MIP-1alpha Ab failed to affect either the extent of inflammatory infiltrates or the parasite count in liver and skeletal muscle. To the best of our knowledge, these data are the first in vivo demonstration that Cz.sbnd;C chemokine MIP-1alpha is involved in cellular recruitment during acute infection with T. cruzi, indicating that MIP-1alpha influences macrophage/monocyte influx into target organs.