Macrophage inflammatory protein-1 alpha. A novel chemotactic cytokine for macrophages in rheumatoid arthritis

IL-20: biological functions and clinical implications

IL-20 belongs to the IL-10 family and plays a role in skin inflammation and the development of hematopoietic cells. Little is known about its other biological functions and clinical implications, however. Updated information about IL-20, such as its identification, expression, receptors, signaling, biological activities, and potential clinical implications, is illustrated in this review based on our research and on data available in the literature. Our studies of IL-20 show that it is a pleiotropic cytokine with potent inflammatory, angiogenic, and chemoattractive characteristics. Inflammation and angiogenesis are essential for the pathogenesis of rheumatoid arthritis and atherosclerosis. Based on in vitro data and clinical samples, we demonstrated that IL-20 is involved in the diseases of rheumatoid arthritis and atherosclerosis. In addition, we found in our studies that IL-20 signaled through different molecules in several cells. The present review presents the clinical implications of IL-20 in rheumatoid arthritis and atherosclerosis. It may provide new therapeutic options in the future.

CXCL16-mediated cell recruitment to rheumatoid arthritis synovial tissue and murine lymph nodes is dependent upon the MAPK pathway

OBJECTIVE

Rheumatoid arthritis (RA) is characterized by profound mononuclear cell (MNC) recruitment into synovial tissue (ST), thought to be due in part to tumor necrosis factor alpha (TNFalpha), a therapeutic target for RA. Although chemokines may also be involved, the mechanisms remain unclear. We undertook this study to examine the participation of CXCL16, a novel chemokine, in recruitment of MNCs to RA ST in vivo and to determine the signal transduction pathways mediating this process.

METHODS

Using a human RA ST-SCID mouse chimera, immunohistochemistry, enzyme-linked immunosorbent assay, real-time reverse transcription-polymerase chain reaction, flow cytometry, and in vitro chemotaxis assays, we defined the expression and function of CXCL16 and its receptor, CXCR6, as well as the signal transduction pathways utilized by them for MNC homing in vitro and in vivo.

RESULTS

CXCL16 was markedly elevated in RA synovial fluid (SF) samples, being as high as 145 ng/ml. Intense macrophage and lining cell staining for CXCL16 in RA ST correlated with increased CXCL16 messenger RNA levels in RA ST compared with those in osteoarthritis and normal ST. By fluorescence-activated cell sorting analysis, one-half of RA SF monocytes and one-third of memory lymphocytes expressed CXCR6. In vivo recruitment of human MNCs to RA ST implanted in SCID mice occurred in response to intragraft injection of human CXCL16, a response similar to that induced by TNFalpha. Lipofection of MNCs with antisense oligodeoxynucleotides for ERK-1/2 resulted in a 50% decline in recruitment to engrafted RA ST and a 5-fold decline in recruitment to regional lymph nodes. Interestingly, RA ST fibroblasts did not produce CXCL16 in response to TNFalpha in vitro, suggesting that CXCL16 protein may function in large part independently of TNFalpha.

CONCLUSION

Taken together, these results point to a unique role for CXCL16 as a premier MNC recruiter in RA and suggest additional therapeutic possibilities, targeting CXCL16, its receptor, or its signaling pathways.

The chemokine CXCL13 is a key molecule in autoimmune myasthenia gravis

Myasthenia gravis (MG) is associated with ectopic germinal centers in the thymus. Thymectomy and glucocorticoids are the main treatments but they induce operative risks and side effects, respectively. The aim of this study was to propose new therapies more efficient for MG. We hypothesized that molecules dysregulated in MG thymus and normalized by glucocorticoids may play a key role in thymic pathogenesis. Using gene chip analysis, we identified 88 genes complying with these criteria, the most remarkable being the B-cell chemoattractant (CXCL13). Its expression was increased in thymus and sera of glucocorticoid-untreated patients and decreased in response to treatment in correlation with clinical improvement. Normal B cells were actively chemoattracted by thymic extracts from glucocorticoid-untreated patients, an effect inhibited by anti-CXCL13 antibodies. In the thymus, CXCL13 was preferentially produced by epithelial cells and overproduced by epithelial cells from MG patients. Altogether, our results suggest that a high CXCL13 production by epithelial cells could be responsible for germinal center formation in MG thymus. Furthermore, they show that this gene is a main target of corticotherapy. Thus, new therapies targeting CXCL13 could be of interest for MG and other autoimmune diseases characterized by ectopic germinal center formation.

Critical role for monocyte chemoattractant protein-1 and macrophage inflammatory protein-1alpha in induction of experimental autoimmune myocarditis and effective anti-monocyte chemoattractant protein-1 gene therapy

BACKGROUND

Autoimmune myocarditis is a principal cause of heart failure among young adults and is often a precursor of dilated cardiomyopathy. Monocyte chemoattractant protein-1 (MCP-1) and macrophage inflammatory protein-1alpha (MIP-1alpha) are potent chemotactic factors for mononuclear cells. The inflammatory infiltrate observed in myocardial lesions of myocarditis consists of >70% mononuclear cells. To determine their critical role in the pathogenesis of myocarditis, we inhibited mononuclear cell activation and migration to see if it would affect disease severity and disease prevalence in experimental autoimmune myocarditis (EAM).

METHODS AND RESULTS

In this report, we demonstrated that blockade of MCP-1 or MIP-1alpha with monoclonal antibodies significantly reduced severity of myocarditis in BALB/c mice immunized with cardiac myosin. Similar results were obtained when CCR2-/- and CCR5-/- mice were used. In CCR2-/- mice, not only disease severity but also disease prevalence was reduced. To further inhibit mononuclear cell activation and migration, we transfected the mice before inducing EAM with a dominant-negative inhibitor of MCP-1 gene (7ND). This transfection significantly reduced the disease severity, decreased mRNA expression levels, especially of the chemokines RANTES, MIP-2, IP-10, MCP-1, T-cell activation gene 3, and eotaxin in the myocardium, and resulted in a reduction in cardiac myosin-induced interleukin-1 and interleukin-4 and in an increase in interferon-gamma and interleukin-10 cytokine production by splenocytes.

CONCLUSIONS

Overall, these findings suggest that the chemokines MCP-1 and MIP-1alpha, acting through their receptors CCR2 and CCR5, are important in the induction of EAM and that inhibition of MCP-1 with 7ND gene transfection significantly reduced disease severity. This strategy may be a new feasible form of gene therapy against autoimmune myocarditis.

The importance of T cell interactions with macrophages in rheumatoid cytokine production

The analysis of suppression of cytokines in rheumatoid synovial tissue and fluid pioneered the studies of human cytokines in diseased tissue due to the relative ease of staining samples, even at the height of the inflammatory process. These studies led to the study of synovial cytokine regulation, and the identification of TNF as a therapeutic target, which has been amply validated in clinical trials and now routine therapy. The next key question was how is TNF disregulated in synovium. Are there differences between the mechanisms of synovial TNF production compared to the production of protective TNF during an immune response? Are there differences between the induction of the pro-inflammatory TNF and the anti inflammatory IL-10? The analysis of the interaction of the two most abundant synovial cells, T lymphocytes and macrophages has provided interesting clues to new therapeutic approaches based on disrupting T-macrophage interaction.

Chemokines and leukocyte trafficking in rheumatoid arthritis

Leukocyte infiltration into the joint space and tissues is an essential component of the pathogenesis of rheumatoid arthritis (RA). In this review, we will summarize the current understanding of the mechanisms of leukocyte trafficking into the synovium, focusing on the role of adhesion molecules, chemokines, and chemokine receptors in synovial autoimmune inflammation. The process by which a circulating leukocyte decides to migrate into the synovium is highly regulated and involves the capture, firm adhesion, and transmigration of cells across the endothelial monolayer. Adhesion molecules and chemokine signals function in concert to mediate this process and to organize leukocytes into distinct structures within the synovium. Chemokines play a key regulatory role in organ-specific leukocyte trafficking and activation by affecting integrin activation, chemotaxis, effector cell function, and cell survival. Consequently, chemokines, their receptors, and downstream signal transduction molecules are attractive therapeutic targets for RA.

Chemokine receptors Ccr1, Ccr2, and Ccr5 mediate neutrophil migration to postischemic tissue

Leukocyte infiltration of reperfused tissue is a key event in the pathogenesis of ischemia-reperfusion. However, the role of chemokine receptors Ccr1, Ccr2, and Ccr5 for each single step of the postischemic recruitment process of leukocytes has not yet been characterized. Leukocyte rolling, firm adherence, transendothelial, and extravascular migration were analyzed in the cremaster muscle of anaesthetized C57BL/6 mice using near-infrared reflected light oblique transillumination microscopy. Prior to 30 min of ischemia as well as at 5, 30, 60, 90, and 120 min after onset of reperfusion, migration parameters were determined in wild-type, Ccr1-/-, Ccr2-/-, and Ccr5-/- mice. Sham-operated wild-type mice without ischemia were used as controls. No differences were detected in numbers of rolling leukocytes among groups. In contrast, the number of firmly adherent leukocytes was increased significantly in wild-type mice as compared with sham-operated mice throughout the entire reperfusion phase. Already after 5 min of reperfusion, this increase was reduced significantly in Ccr1-/- and Ccr5-/- mice, whereas only in Ccr2-/- mice, was adherence attenuated significantly at 120 min after onset of reperfusion. Furthermore, after 120 min of reperfusion, the number of transmigrated leukocytes (>80% Ly-6G+ neutrophils) was elevated in wild-type mice as compared with sham-operated animals. This elevation was significantly lower in Ccr1-/-, Ccr2-/-, and Ccr5-/- mice. Leukocyte extravascular migration distances were comparable among groups. In conclusion, these in vivo data demonstrate that Ccr1, Ccr2, and Ccr5 mediate the postischemic recruitment of neutrophils through effects on intravascular adherence and subsequent transmigration.

Arsenic Trioxide Induces Apoptosis of Human Monocytes during Macrophagic Differentiation through Nuclear Factor-κB-Related Survival Pathway Down-Regulation

Arsenic trioxide (As(2)O(3)) is known to be toxic toward leukemia cells. In this study, we determined its effects on survival of human monocytic cells during macrophagic differentiation, an important biological process involved in the immune response. As(2)O(3) used at clinically relevant pharmacological concentrations induced marked apoptosis of human blood monocytes during differentiation with either granulocyte-macrophage colony-stimulating factor or macrophage colony-stimulating factor. Apoptosis of monocytes was associated with increased caspase activities and decreased DNA binding of p65 nuclear factor-kappaB (NF-kappaB); like As(2)O(3), the selective NF-kappaB inhibitor (E)-3-[(4-methylphenyl)-sulfonyl]-2-propenenitrile (Bay 11-7082) strongly reduced survival of differentiating monocytes. The role of NF-kappaB in arsenic toxicity was also studied in promonocytic U937 cells during phorbol 12-myristate 13-acetate-induced macrophagic differentiation. In these cells, As(2)O(3) first reduced DNA binding of p65 NF-kappaB and subsequently induced apoptosis. In addition, overexpression of the p65 NF-kappaB subunit, following stable infection with a p65 retroviral expressing vector, increased survival of As(2)O(3)-treated U937 cells. As(2)O(3) specifically decreased protein levels of X-linked inhibitor of apoptosis protein and FLICE-inhibitory protein, two NF-kappaB-regulated genes in both U937 cells and blood monocytes during their differentiations. Finally, As(2)O(3) was found to inhibit macrophagic differentiation of monocytic cells when used at cytotoxic concentrations; however, overexpression of the p65 NF-kappaB subunit in U937 cells reduced its effects toward differentiation. In contrast to monocytes, well differentiated macrophages were resistant to low concentrations of As(2)O(3). Altogether, our study demonstrates that clinically relevant concentrations of As(2)O(3) induced marked apoptosis of monocytic cells during in vitro macrophagic differentiation likely through inhibition of NF-kappaB-related survival pathways.

Amelioration of rat adjuvant-induced arthritis by Met-RANTES

OBJECTIVE

CC chemokines and their receptors play a fundamental role in trafficking and activation of leukocytes at sites of inflammation, contributing to joint damage in rheumatoid arthritis. Met-RANTES, an amino-terminal-modified methionylated form of RANTES (CCL5), antagonizes the binding of the chemokines RANTES and macrophage inflammatory protein 1alpha (MIP-1alpha; CCL3) to their receptors CCR1 and CCR5, respectively. The aim of this study was to investigate whether Met-RANTES could ameliorate adjuvant-induced arthritis (AIA) in the rat.

METHODS

Using immunohistochemistry, enzyme-linked immunosorbent assay, real-time reverse transcription-polymerase chain reaction, Western blot analysis, adoptive transfer, and chemotaxis, we defined joint inflammation, bony destruction, neutrophil and macrophage migration, Met-RANTES binding affinity to rat receptors, proinflammatory cytokine and bone marker levels, CCR1 and CCR5 expression and activation, and macrophage homing into joints with AIA.

RESULTS

Administration of Met-RANTES as a preventative reduced the severity of joint inflammation. Administration of Met-RANTES to ankles with AIA showed decreases in inflammation, radiographic soft tissue swelling, and bone erosion. Met-RANTES significantly reduced the number of neutrophils and macrophages at the peak of arthritis compared with saline-injected controls. Competitive chemotaxis in peripheral blood mononuclear cells demonstrated that Met-RANTES inhibited MIP-1alpha and MIP-1beta at 50% inhibition concentrations of 5 nM and 2 nM, respectively. Furthermore, levels of tumor necrosis factor alpha, interleukin-1beta, macrophage colony-stimulating factor, and RANKL were decreased in joints with AIA in the Met-RANTES group compared with the control group. Interestingly, the expression and activation of CCR1 and CCR5 in the joint were down-regulated in the Met-RANTES group compared with the control group. Functionally, Met-RANTES administration decreased adoptively transferred peritoneal macrophage homing into the joint.

CONCLUSION

The data suggest that the targeting of Th1-associated chemokine receptors reduce joint inflammation, bone destruction, and cell recruitment into joints with AIA.

Role of glucocorticoid‐induced TNF receptor family gene (GITR) in collagen‐induced arthritis

In rheumatoid arthritis (RA), a widespread autoimmune/inflammatory joint disease, early activation of effector CD4+ T lymphocytes, and cytokine production is followed by recruitment of other inflammatory cells, production of a range of inflammation mediators, tissue damage, and disease. GITR (glucocorticoid-induced TNFR family-related gene), a costimulatory molecule for T lymphocytes, increases CD4+CD25- effector T cell activation while inhibiting suppressor activity of CD4+CD25+ T regulatory (Treg) cells. We analyzed the role of GITR in type II collagen (CII) -induced arthritis (CIA) using GITR-/- and GITR+/+ mice. Results indicate significantly less CIA induction in GITR-/- mice than in GITR+/+ mice, with marked differences in erythema, edema, neutrophil infiltration, joint injury, and bone erosion. Production of IFNgamma, IL-6, TNFalpha, MIP-1alpha, and MIP-2, inducible NOS (iNOS), COX-2, and nitrotyrosine poly-ADP-ribose (PAR) were also less in CII-treated GITR-/- mice. Although CD4+CD25+ Treg cells from GITR+/+ and GITR-/- CII-challenged mice exerted similar suppressor activity in vitro, GITR triggering abrogated GITR+/+ Treg suppressor activity and costimulated CD4+CD25- GITR+/+ effector cells. Furthermore, Treg cells from GITR-/- protected more than Treg cells from GITR+/+ mice against CIA when cotransferred with Treg-depleted splenocytes from arthritic GITR+/+ animals into severe combined immunodeficient (SCID) mice. In conclusion, GITR plays a critical role in the immunological response against CII and in the development of CIA.

Gingival crevicular fluid EMAP-II, MIP-1alpha and MIP-1beta levels of patients with periodontal disease

BACKGROUND

Periodontal diseases may differ, which could be attributed to the factors that might modify the host response to microbial pathogens. The aim of this study was to examine gingival crevicular fluid (GCF) levels of EMAP-II, MIP-1alpha and MIP-1beta in patients with different periodontal diseases (EMAP-II, endothelial-monocyte activating polypeptide; MIP-1alpha, macrophage inflammatory protein-1alpha; MIP-1beta, macrophage inflammatory protein-1beta).

METHODS

Eighty-two subjects were included in this study. GCF samples were collected from 26 patients with generalized aggressive periodontitis (G-AgP), 26 patients with chronic periodontitis (CP), 15 with gingivitis and 15 periodontally healthy subjects. Clinical periodontal parameters were recorded. GCF EMAP-II, MIP-1alpha and MIP-1beta levels were quantified by enzyme immunoassay.

RESULTS

GCF EMAP-II levels of G-AgP group were higher than those of gingivitis and healthy groups (p<0.008). G-AgP group showed a trend for higher GCF EMAP-II levels compared with CP group (p>0.008). G-AgP, CP, gingivitis and healthy groups had comparable GCF MIP-1alpha and MIP-1beta levels.

CONCLUSIONS

Our results suggest that elevated GCF EMAP-II could contribute to the pathogenesis of G-AgP. Alternatively, EMAP-II reflects the extent of the inflammatory activity in the periodontal tissues. At this point, MIP-1alpha and MIP-1beta levels in GCF do not seem to play a discriminatory role in periodontitis. Our data document for the first time the essential role of EMAP-II in the pathogenesis of different periodontal diseases.

The clinical potential of chemokine receptor antagonists

Chemokines belong to a family of chemotactic cytokines that direct the migration of immune cells towards sites of inflammation. They mediate their biological effects by binding to cell surface receptors, which belong to the G protein-coupled receptor superfamily. Since chemokines and their receptors have been implicated in the pathophysiology of a number of autoinflammatory diseases, chemokine receptor antagonists could prove to be useful therapeutics to target these diseases. Here, we review the role of chemokines in autoimmunity, concentrating mainly on the chemokine receptors CCR1 and CCR5, and discuss the potential utility of antagonists that target these 2 receptors as they progress through the clinic.

Proteolysis of macrophage inflammatory protein-1alpha isoforms LD78beta and LD78alpha by neutrophil-derived serine proteases

Macrophage inflammatory protein-1alpha (MIP-1alpha) is a chemokine that leads to leukocyte recruitment and activation at sites of infection. Controlling chemokine activity at sites of infection is important, since excess accumulation of leukocytes may contribute to localized tissue damage. Neutrophil-derived serine proteases modulate the bioactivity of chemokine and cytokine networks through proteolytic cleavage. Because MIP-1alpha is temporally expressed with neutrophils at sites of infection, we examined proteolysis of MIP-1alpha in vitro by the neutrophil-derived serine proteases: cathepsin G, elastase, and proteinase 3. Recombinant human MIP-1alpha isoforms LD78beta and LD78alpha were expressed and purified, and the protease cleavage sites were analyzed by mass spectrometry and peptide sequencing. Chemotactic activities of parent and cleavage molecules were also compared. Both LD78beta and LD78alpha were cleaved by neutrophil lysates at Thr16-Ser17, Phe24-Ile25, Tyr28-Phe29, and Thr31-Ser32. This degradation was inhibited by serine protease inhibitors phenylmethylsulfonyl fluoride and 4-(2-aminoethyl)-benzenesulfonyl fluoride. Incubation of the substrates with individual proteases revealed that cathepsin G preferentially cleaved at Phe24-Ile25 and Tyr28-Phe29, whereas elastase and proteinase 3 cleaved at Thr16-Ser17 and Thr31-Ser32. Proteolysis of LD78beta resulted in loss of chemotactic activity. The role of these proteases in LD78beta and LD78alpha degradation was confirmed by incubation with neutrophil lysates from Papillon-Lefevre syndrome patients, demonstrating that the cell lysates containing inactivated serine proteases could not degrade LD78beta and LD78alpha. These findings suggest that severe periodontal tissue destruction in Papillon-Lefevre syndrome may be related to excess accumulation of LD78beta and LD78alpha and dysregulation of the microbial-induced inflammatory response in the periodontium.

Expression of cytokine mRNA and protein in joints and lymphoid organs during the course of rat antigen-induced arthritis

Cytokine expression was assessed during antigen-induced arthritis (AIA) in synovial membrane (SM), inguinal lymph node (LN), and spleen using competitive RT-PCR and sandwich ELISA. In the SM, early elevations of IL-1β and IL-6 mRNA (by 6 hours; 450- and 200-fold, respectively) correlated with the joint swelling; a 6-fold increase in tumor necrosis factor α (TNFα) was not significant. Not only IL-2 and IFN-γ (which increased 10,000-fold and 200-fold, respectively), but also IL-5 and IL-10, increased acutely (6 hours – day 1; 3-fold and 35-fold, respectively) in the SM. In general, the protein levels in the SM for IL-1β, IL-6, TNFα, IFN-γ, IL-4, and IL-10 (increase from 4-fold to 15-fold) matched the course of mRNA expression. In the inguinal LN, there were early mRNA elevations of IL-6 (a 2.5-fold increase by 6 hours, which correlated positively with the joint swelling) and IL-2 (4-fold by 6 hours), as well as later rises of IL-4 and IL-5 (2.5- and 4-fold, respectively, by day 3). No significant elevations of the corresponding proteins in this tissue were observed, except for IL-1β (by day 6) and IL-10 (by day 1). In the spleen, there were significant mRNA elevations at 6 hours of IL-1β (1.5-fold), IL-6 (4-fold; positively correlated with the joint swelling), IFN-γ (3-fold), and IL-2 (7- to 10-fold). IL-5 and IL-10 (2- and 3-fold, respectively) peaked from 6 hours to day 3 in the spleen. Increases of the corresponding proteins were significant in comparison with day 0 only in the case of IL-2 (day 6). By day 6 (transition to the chronic phase), the mRNA for cytokines declined to or below prearthritis levels in all the tissues studied except for IL-1β in the SM and IL-6 in the spleen. AIA is thus characterized by four phenomena: early synovial activation of macrophages, T helper (Th)1-like, and Th2-like cells; late, well-segregated Th2-like responses in the inguinal LN; late, overlapping Th1-like/Th2-like peaks in the spleen; and chronic elevation of synovial IL-1β mRNA and spleen IL-6 mRNA.

CC and CXC chemokine receptors mediate migration, proliferation, and matrix metalloproteinase production by fibroblast-like synoviocytes from rheumatoid arthritis patients

OBJECTIVE

To explore the potential involvement of the chemokine system in synoviocyte-mediated tissue destruction in rheumatoid arthritis (RA), we studied the expression profile of chemokine receptors and their function in the migration, proliferation, and matrix metalloproteinase (MMP) production of cultured fibroblast-like synoviocytes (FLS) from RA patients.

METHODS

The presence of CC and CXC chemokine receptors on cultured FLS was studied at the messenger RNA (mRNA) level by reverse transcriptase-polymerase chain reaction and at the cell surface expression level by flow cytometry. Variations in cytosolic calcium influx induced by chemokine stimulation were assessed by flow cytometry on Fura Red-preloaded FLS. Two-compartment transwell chambers were used for FLS chemotaxis assays. Cell growth was measured by a fluorescence-based proliferation assay. Gelatinase and collagenase activities were determined by a fibril degradation assay and zymography.

RESULTS

FLS constitutively expressed the receptors CCR2, CCR5, CXCR3, and CXCR4, both at the cell surface and mRNA levels, but failed to express CCR3 and CCR6. Significant intracytosolic calcium influx was observed on FLS challenged with monocyte chemotactic protein 1 (MCP-1), stromal cell-derived factor 1alpha (SDF-1alpha), and interferon-inducible protein 10 (IP-10). Stimulation with MCP-1, SDF-1alpha, IP-10, and monokine induced by interferon-gamma enhanced the migration and proliferation of FLS. These chemokines, in addition to RANTES, increased in a dose- and time-dependent manner the gelatinase and collagenase activities in cell-free supernatants of cultured FLS. Interestingly, the chemokine-mediated up-regulation of MMP activities was significantly abrogated by the presence of anti-interleukin-1beta, but not anti-tumor necrosis factor alpha, blocking antibodies.

CONCLUSION

These data suggest that through modulation of the migration, proliferation, and MMP production by FLS, the chemokine system may play a more direct role in the destructive phase of RA than is currently suspected, and thus emphasize the relevance of chemokines and their receptors as potential therapeutic targets in this disease.

Extracellular cytochrome c, a mitochondrial apoptosis-related protein, induces arthritis

OBJECTIVES

The aim of the study was to assess the role of extracellular cytochrome c as an inducer of joint inflammation and to examine its levels in sera and synovial fluids of rheumatoid arthritis (RA) patients.

METHODS

Mice were injected intra-articularly with different doses of cytochrome c and joints were evaluated histopathologically and immunohistochemically 3 and 10 days later. In addition, mouse spleen cells were stimulated with different concentrations of cytochrome c, followed by assessment of NF-kappaB activation and cytokine production. Sera and synovial fluid from RA patients and sera from healthy individuals were assessed with respect to cytochrome c levels by an enzyme-linked immunoassay technique.

RESULTS

Histopathological signs of arthritis were evident in 75% of animals following intra-articular injection of cytochrome c. Synovitis was characterized by influx of Mac-1+ cells. In vivo depletion of neutrophils and monocytes led to abrogation of arthritis. Stimulation of mouse spleen cells in vitro with cytochrome c resulted in activation of NF-kappaB and release of proinflammatory cytokines and chemokines. Cytochrome c levels in RA patients' sera were significantly lower than in healthy controls. Further, cytochrome c levels in synovial fluid were significantly lower than in corresponding blood samples.

CONCLUSIONS

Our findings demonstrate that extracellular cytochrome c displays direct proinflammatory properties mediated by activation of NF-kappaB and causing neutrophil and monocyte triggered inflammation. We hypothesize that decreased levels of cytochrome c in RA patients reflect consumption of this molecule in the synovial tissue, decreasing apoptosis and shifting the balance towards inflammation.

Possible involvement of MIP-1alpha in the recruitment of osteoclast progenitors to the distal tibia in rats with adjuvant-induced arthritis

In the rat model of rheumatoid arthritis, a marked formation of osteoclasts is found in the distal tibia and the metatarsal bone. It was therefore postulated that osteoclast progenitors would be increased in the bone marrow cavities of rats with adjuvant-induced arthritis (AA rats). Bone marrow cells obtained from tibia of AA rats were cultured to form cells in the osteoclast lineage to access the number of osteoclast progenitors. Unexpectedly, only a suppressed level of osteoclast progenitors was detected in the diaphyseal bone marrow of tibia in AA rats. Distribution of osteoclast progenitors in the bone marrow cavity was examined, and it was shown that osteoclast progenitors accumulated in the distal tibia. Macrophage inflammatory protein (MIP)-1alpha, an osteoclastogenic CC chemokine, was expressed in ED-1-positive macrophages localizing in the distal tibia with marked bone destruction. Chemotaxis studies showed that MIP-1alpha expressed significant activity towards bone marrow cells. The suppressed level of osteoclastogenesis in bone marrow cells of AA rats was restored to a normal level by the addition of MIP-1alpha. It was suggested that MIP-1alpha is involved in the migration of osteoclast progenitors to the distal tibia as well as in osteoclastogenesis in AA rats. In these rats, in situ hybridization of the distal tibia with a high level of bone destruction showed significant expression of Receptor activator nuclear factor kappaB ligand (RANKL) messenger RNA in aggregates of multinucleated osteoclast-like cells present in the bone marrow cavity, a unique pathological feature for these rats. Migrated osteoclast progenitors are thought to be efficiently differentiated into osteoclasts in response to RANKL expressed by the aggregates of osteoclast-like cells under the influence of the MIP-1alpha. Such positive-feedback regulation of osteoclastogenesis could result in the highest recruitment of active osteoclasts in the area of marked bone destruction.

Increased expression of CCL18, CCL19, and CCL17 by dendritic cells from patients with rheumatoid arthritis, and regulation by Fc gamma receptors

BACKGROUND

Dendritic cells (DC) have a role in the regulation of immunity and tolerance, attracting inflammatory cells by the production of various chemokines (CK). Fc gamma receptors (Fc gamma R) may be involved in regulation of the DC function.

OBJECTIVE

To assess the expression of CK by immature (iDC) and mature DC (mDC) and its regulation by Fc gamma R in patients with RA and healthy donors (HC).

METHODS

Expression of CK by DC from patients with RA and from HC was determined by real time quantitative PCR and ELISA. DC were derived from monocytes following standardised protocols. To study the potential regulation by Fc gamma R, iDC were stimulated with immune complexes (IC) during lipopolysaccharide (LPS) induced maturation. The presence of CK was studied in synovial tissue from patients with RA, osteoarthritis, and healthy subjects by RT-PCR and immunohistochemistry.

RESULTS

iDC from patients with RA had markedly increased mRNA levels of the CK CCL18 and CXCL8. Upon maturation with LPS, expression of CCL18, CCL19, CXCL8, CCL3, and CCL17 increased dramatically, reaching significantly higher levels in patients with RA. Monocytes failed to express these CK, except for CXCL8 and CCL3. IC-mediated triggering of the Fc gamma R on DC from patients with highly active RA down regulated all CK, whereas the reverse was seen when DC from patients with low disease activity and healthy donors were stimulated. CCL18 was significantly increased in RA synovial tissue.

CONCLUSION

Increased CK expression by DC was found in patients with RA. This expression is partly regulated by Fc gamma R triggering and results in an inhibitory DC subtype in RA upon Fc gamma R-mediated triggering.

Activated protein C inhibits the release of macrophage inflammatory protein-1-alpha from THP-1 cells and from human monocytes

Several lines of evidence have implicated activated protein C (APC) to be an endogenous inhibitor of the inflammatory septic cascade. APC may exhibit direct anti-inflammatory properties, independent of its antithrombotic effects. Chemokines influence the interaction of monocytes at the endothelium during infection and sepsis and are involved in the molecular events leading to an adverse and lethal outcome of sepsis. Defining regulatory mechanisms on the monocytic release profile of the proinflammatory C-C chemokines macrophage inflammatory protein-1-alpha (MIP-1-alpha) and monocyte chemoattractant protein-1 (MCP-1) might have therapeutic implications for the treatment of sepsis. We established a monocytic cell model of inflammation by the addition of lipopolysaccharide (LPS) and examined the effect of human APC on LPS-stimulated chemokine release from the monocytic cell line THP-1. We found that human APC in supra-physiological concentrations of 2.5-10 microg/ml inhibited the LPS-induced release of the chemokines MIP-1-alpha and MCP-1, as measured by enzyme-linked immunosorbent assays (ELISA) at 6 up to 24 h. In addition to experiments on THP-1 cells, recombinant human APC in concentrations of 50 ng/ml was found to have an inhibiting effect on the release of MIP-1-alpha from freshly isolated mononuclear cells of septic patients. The ability of APC to decrease the release of the C-C chemokine MIP-1-alpha from the monocytic cell line THP-1 and from human monocytes may identify a novel immunomodulatory pathway by which APC exerts its anti-inflammatory action and may contribute to control the inflammatory response in sepsis.

Chemokines in joint disease: the key to inflammation?

Targeting chemokines and/or chemokine receptors appears to be an intriguing new approach to treating chronic inflammatory disorders like rheumatoid arthritis, inflammatory bowel diseases, multiple sclerosis, and transplant rejections. The involvement of chemokines and chemokine receptors in inflammatory joint diseases, the in vitro and in vivo characteristics of the chemokine family in inflammatory joint disease, and initial clinical data on chemokine blockade in patients with rheumatoid arthritis suggest that targeting the chemokine and chemokine receptor family might provide a new, promising antirheumatic strategy.

Endothelial cell phenotypes in the rheumatoid synovium: activated, angiogenic, apoptotic and leaky

Endothelial cells are active participants in chronic inflammatory diseases. These cells undergo phenotypic changes that can be characterised as activated, angiogenic, apoptotic and leaky. In the present review, these phenotypes are described in the context of human rheumatoid arthritis as the disease example. Endothelial cells become activated in rheumatoid arthritis pathophysiology, expressing adhesion molecules and presenting chemokines, leading to leukocyte migration from the blood into the tissue. Endothelial cell permeability increases, leading to oedema formation and swelling of the joints. These cells proliferate as part of the angiogenic response and there is also a net increase in the turnover of endothelial cells since the number of apoptotic endothelial cells increases. The endothelium expresses various cytokines, cytokine receptors and proteases that are involved in angiogenesis, proliferation and tissue degradation. Associated with these mechanisms is a change in the spectrum of genes expressed, some of which are relatively endothelial specific and others are widely expressed by other cells in the synovium. Better knowledge of molecular and functional changes occurring in endothelial cells during chronic inflammation may lead to the development of endothelium-targeted therapies for rheumatoid arthritis and other chronic inflammatory diseases.

Role of circulating cytokines and chemokines in exertional heatstroke

OBJECTIVE

The interplay between inflammatory and anti-inflammatory cytokines, as well as chemokines, has not been well explored in exertional heatstroke.

DESIGN

Prospective, observational study.

PATIENTS

Seventeen military recruits who developed exertional heatstroke and 17 exertional controls who did not develop exertional heatstroke during the same training exercises.

SETTING

University teaching hospital.

MEASUREMENTS AND MAIN RESULTS

The severity of exertional heatstroke was evaluated using a Simplified Acute Physiology Score. Plasma cytokines and chemokines were determined using enzyme-linked immunosorbent assay kits. Body temperatures were 41.2 +/- 1.2 degrees C and 37.6 +/- 0.8 degrees C in exertional heatstroke and exertional controls, respectively. Significantly, plasma cytokines including interleukin (IL)-1beta (3.1 +/- 1.6 vs. 1.2 +/- 0.8 pg/mL; p <.05), tumor necrosis factor alpha (4.9 +/- 4.1 vs. 1.2 +/- 2.4 pg/mL; p <.05), IL-6 (15.8 +/- 3.2 vs. 1.2 +/- 1.2 pg/mL; p <.01), interferon gamma (7.3 +/- 4.9 vs. 2.4 +/- 4.1 pg/mL; p <.01), IL-2 receptor (1568 +/- 643 vs. 610 +/- 214 pg/mL; p <.01), IL-4 (2.5 +/- 1.2 vs. 1.2 +/- 0.8 pg/mL; p <.05), and IL-10 (12.9 +/- 9.4 vs. 2.5 +/- 4.9 pg/mL; p <.01) and serum chemokines IL-8 (84.2 +/- 79.9 vs. 10.4 +/- 3.2 pg/mL; p <.01), monocyte chemoattractant protein 1 (959 +/- 589 vs. 158 +/- 217 pg/mL; p <.01), and RANTES (12464 +/- 10505 vs. 5570 +/- 2894 pg/mL; p <.01) were elevated in exertional heatstroke compared with exertional controls. Among cytokines, IL-6, interferon gamma, and IL-2 receptor were positively correlated with Simplified Acute Physiology Score (r =.573, p <.01; r =.625, p <.01; and r =.56, p <.05, respectively). Among chemokines, only serum monocyte chemoattractant protein 1 was positively correlated with Simplified Acute Physiology Score (r =.78, p <.001). There was no correlation between either cytokines or chemokines and body temperature.

CONCLUSIONS

Proinflammatory cytokines IL-1beta, tumor necrosis factor alpha, IL-6; T helper 1 cytokines INF-gamma and IL-2 receptor; and chemokines IL-8, monocyte chemoattractant protein 1, and RANTES are increased in patients with exertional heatstroke. T helper 2 cytokines may play a role as anti-inflammatory cytokines. IL-6, interferon gamma, IL-2 receptor, and monocyte chemoattractant protein 1 may serve as prognostic indicators of disease severity in exertional heatstroke.

Reduction in the evolution of murine type II collagen-induced arthritis by treatment with rosiglitazone, a ligand of the peroxisome proliferator-activated receptor gamma

OBJECTIVE

The peroxisome proliferator-activated receptor gamma (PPARgamma) is a member of the nuclear receptor superfamily of ligand-dependent transcription factors related to retinoid, steroid, and thyroid hormone receptors. The thiazolidinedione rosiglitazone is a PPARgamma ligand that modulates the transcription of target genes. The aim of this study was to investigate the effects of rosiglitazone on the inflammatory response in mice with collagen-induced arthritis (CIA).

METHODS

CIA was induced in DBA/1J mice by an intradermal injection of 100 microl of an emulsion of bovine type II collagen (CII; 100 microg) in Freund's complete adjuvant (CFA) at the base of the tail. On day 21, a second injection of CII in CFA was administered. Rosiglitazone (10 mg/kg/day) or vehicle (10% DMSO) was administered beginning on day 25 (arthritis onset) until day 35. Clinical, radiographic, histopathologic, and laboratory assessments were performed.

RESULTS

Mice immunized with CII in CFA developed erosive arthritis of the hind paws. Macroscopic evidence of CIA first appeared as periarticular erythema and edema of the hind paws. The incidence of CIA was 100% by day 27 in the CII-challenged mice, and the severity progressed over the 35-day study period. Radiographic evaluation revealed focal resorption of bone. Histopathologic features of CIA included erosion of cartilage at the joint margins. Rosiglitazone treatment ameliorated the clinical signs on days 26-35 and improved the histologic findings in the joint and paw. The degree of oxidative and nitrosative damage was significantly reduced in rosiglitazone-treated mice, as indicated by elevation of malondialdehyde levels, formation of nitrotyrosine, and activation of poly(ADP-ribose) polymerase. Plasma levels of the proinflammatory cytokines tumor necrosis factor, interleukin-1beta, and interleukin-6 were also significantly reduced by rosiglitazone treatment.

CONCLUSION

These data demonstrate that rosiglitazone exerts an antiinflammatory effect on chronic inflammation and is able to ameliorate the tissue damage associated with CIA.

Augmented production of chemokines by the interaction of type II collagen-reactive T cells with rheumatoid synovial fibroblasts

OBJECTIVE

To determine the impact of type II collagen (CII)-reactive T cells on the production of chemokines in the joints of patients with rheumatoid arthritis (RA).

METHODS

T cell proliferative responses to bovine CII were assayed in synovial fluid (SF) mononuclear cells and peripheral blood mononuclear cells. CII-stimulated T cells were cocultured with fibroblast-like synoviocytes (FLS). The expression of interleukin-8 (IL-8), monocyte chemoattractant protein 1 (MCP-1), and macrophage inflammatory protein 1 alpha (MIP-1 alpha) in the sera, SF, and supernatant of the CII-stimulated T cells and FLS coculture was measured by enzyme-linked immunosorbent assays.

RESULTS

The levels of IL-8, MCP-1, and MIP-1 alpha in SF were significantly higher than those in paired sera of RA patients. IL-8, MCP-1, and MIP-1 alpha levels in SF were strongly correlated with T cell responses to CII. When FLS were cocultured with CII-stimulated T cells, the production of IL-8, MCP-1, and MIP-1 alpha was significantly increased. This increase correlated well with the T cell proliferative response to CII. Chemokine production by coculture of CII-stimulated T cells and FLS was mediated mainly by direct cell-cell contact through CD40 ligand-CD40 engagement.

CONCLUSION

Our data indicate that the presence of CII-reactive T cells in RA joints can increase the production of chemokines such as IL-8, MCP-1, and MIP-1 alpha through interaction with FLS. This chemokine production is mediated by cell-cell contact, including CD40 ligand-CD40 engagement. These results suggest that CII-reactive T cells play a crucial role in the amplification and perpetuation of the inflammatory process in the rheumatoid synovium.

Chemokine receptor expression and in vivo signaling pathways in the joints of rats with adjuvant-induced arthritis

OBJECTIVE

This study was undertaken to characterize the role of CC chemokines and their receptors in rat adjuvant-induced arthritis (AIA), a model for rheumatoid arthritis (RA). Furthermore, we investigated the signaling pathways associated with CC receptors as well as the cell type distribution of the receptors.

METHODS

Using TaqMan real-time reverse transcription-polymerase chain reaction, Western blot analysis, and immunohistochemistry, we defined chemokine and chemokine receptor messenger RNA (mRNA) expression, CC chemokine receptor (CCR) protein activation during the disease course, CCR-associated signaling pathways, and immunopositive CCR5, phosphorylated signal transducer and activator of transcription 1 (p-STAT-1), and p-STAT-3 cells in rat AIA versus control joints.

RESULTS

We showed significant up-regulation of CCR1, CCR2, CCR5, and macrophage inflammatory protein 1beta/CCL4 mRNA in AIA on post-adjuvant injection day 18, coincident with peak inflammation. Additionally, increases in tyrosine phosphorylation of CCR1 (days 14, 18, 21, and 24), CCR2 (days 14 and 18), and CCR5 (days 14, 18, and 21) were detected in AIA rats compared with control (nonarthritic) rats. JAK-1, STAT-1, and STAT-3 were associated with CCR1 and were highly tyrosine phosphorylated on days 14 and 18. Moreover, CCR2 was associated with JAK-2, STAT-1, and STAT-3 on day 18. The association of STAT-1 and STAT-3 with CCR5 on days 18 and 21 correlated with JAK-1 phosphorylation and binding on day 18. However, the activation of JNK was not associated with CCR5 activation in rat AIA. Immunohistochemical analysis demonstrated that the expression of CCR5, p-STAT-1, and p-STAT-3 was detected on synovial lining cells, macrophages, and endothelial cells in arthritic rat ankles on post-adjuvant injection day 18. While the majority of the CCR5 and p-STAT-1 immunostaining was on synovial lining cells and macrophages, p-STAT-3 was predominantly expressed on endothelial cells.

CONCLUSION

CCR1, CCR2, and CCR5 mRNA expression and tyrosine phosphorylation increased with peak inflammation in the AIA model. CCR1, CCR2, and CCR5 tyrosine phosphorylation are associated with the JAK/STAT-1/STAT-3 pathway at different stages of rat AIA, as well as with macrophage and endothelial cell infiltration. However, their signaling activation overlaps with peak inflammation. Up-regulation and activation of CCRs may play a role in macrophage and endothelial cell infiltration in rat AIA joints in addition to activating the associated signaling pathways. The downstream intermediate signaling proteins associated with CC receptors may be used as potential tools to control inflammation in RA.

CP-481,715, a potent and selective CCR1 antagonist with potential therapeutic implications for inflammatory diseases

The chemokines CCL3 and CCL5, as well as their shared receptor CCR1, are believed to play a role in the pathogenesis of several inflammatory diseases including rheumatoid arthritis, multiple sclerosis, and transplant rejection. In this study we describe the pharmacological properties of a novel small molecular weight CCR1 antagonist, CP-481,715 (quinoxaline-2-carboxylic acid [4(R)-carbamoyl-1(S)-(3-fluorobenzyl)-2(S),7-dihydroxy-7-methyloctyl]amide). Radiolabeled binding studies indicate that CP-481,715 binds to human CCR1 with a Kd of 9.2 nm and displaces 125I-labeled CCL3 from CCR1-transfected cells with an IC50 of 74 nm. CP-481,715 lacks intrinsic agonist activity but fully blocks the ability of CCL3 and CCL5 to stimulate receptor signaling (guanosine 5'-O-(thiotriphosphate) incorporation; IC50 = 210 nm), calcium mobilization (IC50 = 71 nm), monocyte chemotaxis (IC50 = 55 nm), and matrix metalloproteinase 9 release (IC50 = 54 nm). CP-481,715 retains activity in human whole blood, inhibiting CCL3-induced CD11b up-regulation and actin polymerization (IC50 = 165 and 57 nm, respectively) on monocytes. Furthermore, it behaves as a competitive and reversible antagonist. CP-481,715 is >100-fold selective for CCR1 as compared with a panel of G-protein-coupled receptors including related chemokine receptors. Evidence for its potential use in human disease is suggested by its ability to inhibit 90% of the monocyte chemotactic activity present in 11/15 rheumatoid arthritis synovial fluid samples. These data illustrate that CP-481,715 is a potent and selective antagonist for CCR1 with therapeutic potential for rheumatoid arthritis and other inflammatory diseases.

Temporal relationships between circulating levels of CC and CXC chemokines and developing atherosclerosis in apolipoprotein E*3 Leiden mice

OBJECTIVE

CC and CXC chemokines are implicated in leukocyte recruitment during development of atherosclerotic lesions, suggesting circulating levels of chemokines may be useful serum markers of atherogenesis. Serum chemokine concentrations were measured in apolipoprotein (apo) E*3 Leiden mice and their nontransgenic littermates and related to the differing rates of atherogenesis in these animals.

METHODS AND RESULTS

Mice were fed a high-fat, high-cholesterol/cholate (HFC/C) diet for 18 weeks. Circulating levels of JE/monocyte chemotactic protein-1 increased (P<0.05) after 2 to 4 weeks, coincident with development of diet-induced hypercholesterolemia, and remained elevated throughout the study. Circulating KC concentrations increased (P<0.05) after consumption of HFC/C diet; however, unlike JE, serum KC concentrations increased more rapidly in apoE*3 Leiden mice than their nontransgenic littermates. Hepatic expression of JE and KC mRNA were detected by in situ hybridization in all mice fed HFC/C diet. Aortic expression of JE mRNA was seen only in apoE*3 Leiden mice within macrophage-rich atherosclerotic lesions. By contrast, no aortic expression of KC mRNA was detected by in situ hybridization.

CONCLUSIONS

Increases in serum chemokine concentrations did not reflect temporal aortic production of these molecules and proved less predictive than serum cholesterol of the markedly different extent of atheroma in apoE*3 Leiden and nontransgenic mice.

Chemokine blockade and chronic inflammatory disease: proof of concept in patients with rheumatoid arthritis

BACKGROUND

Chemokines and their receptors are considered important contributors in cell migration and inflammation in chronic inflammatory disorders. Chemokines affecting monocytes/macrophages are considered potential therapeutic targets, but no studies of the effects of blocking the chemokine repertoire in humans with a chronic inflammatory disease have been reported.

OBJECTIVE

To carry out a double blind, placebo controlled, phase Ib clinical trial with a specific, oral CCR1 antagonist.

METHODS

16 patients with active rheumatoid arthritis (RA) were randomised 3:1 to active:placebo treatment for 14 days. Synovial biopsy specimens were obtained on days 1 and 15. Immunohistochemistry was used to detect the presence of various cell types before and after treatment and the results measured by digital image analysis. Results before and after treatment were compared by paired t test, and a two sample t test was used to compare the changes from baseline in the two groups.

RESULTS

All patients completed the study. A significant reduction in the number of macrophages (p=0.016), intimal macrophages (p=0.026), and CCR1+cells (p=0.049) in patients treated with the chemokine antagonist compared with the placebo group occurred in the synovium. Significant decreases in overall cellularity, intimal lining layer cellularity, CD4+ T cells, and CD8+ T cells also occurred in treated patients. Cells lacking CCR1 were not affected. Trends towards clinical improvement were seen in the treated patients but not in the placebo group. Severe side effects were not reported.

CONCLUSION

Specific chemokine receptor blockade can result in relevant biological effects in patients with active RA.

Hydrodynamic guiding for addressing subsets of immobilized cells and molecules in microfluidic systems

BACKGROUND

The interest in microfluidics and surface patterning is increasing as the use of these technologies in diverse biomedical applications is substantiated. Controlled molecular and cellular surface patterning is a costly and time-consuming process. Methods for keeping multiple separate experimental conditions on a patterned area are, therefore, needed to amplify the amount of biological information that can be retrieved from a patterned surface area. We describe, in three examples of biomedical applications, how this can be achieved in an open microfluidic system, by hydrodynamically guiding sample fluid over biological molecules and living cells immobilized on a surface.

RESULTS

A microfluidic format of a standard assay for cell-membrane integrity showed a fast and dose-dependent toxicity of saponin on mammalian cells. A model of the interactions of human mononuclear leukocytes and endothelial cells was established. By contrast to static adhesion assays, cell-cell adhesion in this dynamic model depended on cytokine-mediated activation of both endothelial and blood cells. The microfluidic system allowed the use of unprocessed blood as sample material, and a specific and fast immunoassay for measuring the concentration of C-reactive protein in whole blood was demonstrated.

CONCLUSION

The use of hydrodynamic guiding made multiple and dynamic experimental conditions on a small surface area possible. The ability to change the direction of flow and produce two-dimensional grids can increase the number of reactions per surface area even further. The described microfluidic system is widely applicable, and can take advantage of surfaces produced by current and future techniques for patterning in the micro- and nanometer scale.

Dobutamine modulates lipopolysaccharide-induced macrophage inflammatory protein-1alpha and interleukin-8 production in human monocytes

Chemokines mediate the migration of leukocytes to sites of inflammation. The CC chemokine macrophage inflammatory protein (MIP)-1alpha and the CXC chemokine interleukin (IL)-8 are reported to play an important role in early inflammatory stages, wound healing, sepsis, and some cardiovascular diseases, including acute coronary syndromes and congestive heart failure. We conducted this study to investigate the effect of dobutamine on lipopolysaccharide (LPS)-induced MIP-1alpha and IL-8 production by human monocytic THP-1 cells. Monocytes were incubated in vitro with LPS for 4 or 16 h at 37 degrees C in the presence or absence of dobutamine. The effect of dobutamine on MIP-1alpha and IL-8 synthesis was examined by using an enzyme-linked immunosorbent assay, and MIP-1alpha and IL-8 messenger RNA (mRNA) were examined by using reverse transcriptase-polymerase chain reaction. Dobutamine significantly inhibited LPS-induced MIP-1alpha and IL-8 production by THP-1 cells in a dose-dependent manner. Salbutamol had a similar suppressive effect on LPS-stimulated MIP-1alpha and IL-8 production. MIP-1alpha mRNA was also suppressed by 10 micro M dobutamine, whereas, at the same concentration, dobutamine had no significant effect on the IL-8 mRNA level. Moreover, we found that dobutamine suppressed the MIP-1alpha-induced chemotaxis in THP-1 differentiated macrophages. These findings suggest that dobutamine may inhibit macrophage chemotaxis, as well as MIP-1alpha and IL-8 production by monocytes. The site of chemokine regulation is at the transcriptional level for MIP-1alpha and might be at the posttranscriptional level for IL-8.

IMPLICATIONS

Macrophage inflammatory protein (MIP)-1alpha and interleukin (IL)-8 are reported to play an important role in early inflammatory stages, wound healing, sepsis, and some cardiovascular diseases. Our study suggests that dobutamine may inhibit macrophage chemotaxis, as well as lipopolysaccharide-induced MIP-1alpha and IL-8 production by human monocytes.

MCP-1 promoter polymorphism in Spanish patients with rheumatoid arthritis

To investigate the possible role of the polymorphism located in the regulatory region of monocyte chemoattractant protein-1 (MCP-1) gene in the susceptibility to rheumatoid arthritis (RA), a total of 141 Spanish RA patients and 194 controls, previously typed for human leukocyte antigen DRB1* (HLA-DRB1*), were genotyped for -2518 (A/G) MCP-1 gene polymorphism using polymerase chain reaction-restriction fragment length polymorphism. No association between -2518 (A/G) MCP-1 polymorphism and susceptibility to RA was found. Nevertheless, when patients and controls were stratified according to their HLA shared epitope (SE) status, a significant increase in the frequency of genotype GG was found among SE negative (SE-) patients with respect to both SE positive (SE+) patients and SE- controls (16% versus 4% in SE+ patients, pFisher=0.04, odds ratio [OR]=4.4, 95% confidence interval [95%CI]=1.03-21.48; and 4% in SE- controls, pFisher=0.02, OR=4.13, 95%CI=1.10-15.72). In conclusion, MCP-1 polymorphism is slightly associated with the susceptibility to RA in patients lacking the HLA SE.

Regulation of CCR5 expression and MIP-1alpha production in CD4+ T cells from patients with rheumatoid arthritis

Production of CCR5 expression and MIP-1alpha, a ligand of CCR5, by CD4+ T cells from patients with rheumatoid arthritis (RA) were studied. We analysed further the influence of IL-15 stimulation, CD40/CD40 ligand (CD40L) interaction and CCR5 promotor polymorphism. One hundred and fifty-five RA patients and another 155 age- and sex-matched healthy individuals were enrolled. Peripheral CD4+ and double negative (DN) T cells from patients had lower portions of CCR5, whereas synovial CD4+ and DN T cells showed a much higher CCR5 expression. IL-15 significantly up-regulated the expression of CCR5 on purified CD4+ T cells. CD40L expression on synovial CD4+ T cells was increased greatly in CCR5+ portions by IL-15. MIP-1alpha production by synovial CD4+ T cells was also enhanced by IL-15. Co-culture of CD40 expressing synovial fibroblasts with IL-15-activated synovial CD4+ T cells significantly increased MIP-1alpha production. Expression of CCR5 on patients' CD4+ T cells was not influenced by the promotor polymorphism of CCR5 gene. Taken together, these data suggest CCR5+CD4+ T cells infiltrate the inflamed synovium and IL-15 up-regulates CCR5 and CD40L expression further and enhance MIP-1alpha production in synovial CD4+ T cells. Production of MIP-1alpha by synovial fibroblasts is significantly increased by engagement of CD40 with CD40L. Synovial microenvironment plays a potential role in regulation of CCR5+CD4+ T cells in rheumatoid joints.

Elevated monocyte chemoattractant protein-1 levels following thermal injury precede monocyte recruitment to the wound site and are controlled, in part, by tumor necrosis factor-alpha

In previous studies, mice given a full-thickness scald injury had an influx of neutrophils into the skin that followed a local increase in a neutrophil chemoattractant. Because macrophages are known to infiltrate the wound area after neutrophils and are essential for normal wound repair, studies were designed to characterize the time course of macrophage accumulation in the wound and to identify the factor(s) responsible for this influx. A macrophage infiltrate into the wound was observed at 4 days post-injury and persisted through at least 10 days. This influx was preceded by an initial fourfold increase in dermal monocyte chemoattractant protein-1 levels at 24 hours post-injury (p < 0.05). This elevation in monocyte chemoattractant protein-1 was enhanced at 4 and 10 days postburn resulting in a sixfold increase over baseline (p < 0.01). Levels of tumor necrosis factor-alpha, a proinflammatory cytokine known to induce chemokine production, were elevated at 90 minutes after injury in burn- versus sham-injured groups (p < 0.05). Furthermore, administration of tumor necrosis factor-alpha neutralizing antibody in vivo reduced the dermal levels of monocyte chemoattractant protein-1 seen at 10 days postburn by 57% (p < 0.01); however, macrophage accumulation was not altered. Thus, elevated systemic TNF-alpha levels may influence the local chemokine milieu following burn injury.

Chemokines and chemokine receptors in rheumatoid arthritis

Chemokines are chemotactic cytokines involved in a number of pathological processes, including inflammatory conditions. Chemokines play a role in the pathogenesis of various inflammatory diseases. Based on a burgeoning body of literature, RA was chosen as a prototype to discuss this issue. In this review, the authors give a detailed introduction to the classification and function of chemokines and their receptors. This is followed by a discussion of the role of chemokines and chemokine receptors in RA. Chemokines interact with other inflammatory mediators, such as cytokines. Thus, the regulation of chemokine production and the place of chemokines in the network of inflammatory mediators present in the rheumatoid synovium are also reviewed. Finally, potential strategies using anti-chemokine or anti-chemokine receptor biologicals in anti-rheumatic therapy are discussed.

Macrophage activating properties of the tryptophan catabolite picolinic acid

Recent studies have suggested a role for aminoacid catabolites as important regulators of macrophage (Mphi) activities. We reported previously that picolinic acid (PA), a tryptophan catabolite produced under inflammatory conditions and a costimulus with IFNgamma of Mphi effector functions, is a selective inducer of the Mphi inflammatory protein-1alpha (MIP-1alpha) and -1beta (MIPs), two CC-chemokines involved in the elicitation of the inflammatory reactions and in the development of the Th1 responses. In this study, we have investigated the effects of IFNgamma on PA-induced MIPs expression and secretion by mouse Mphi as well as the regulation of MIP-1alpha/beta receptor, CCR5, by both stimuli alone or in combination. We demonstrated that IFNgamma inhibited MIPs mRNA stimulation by PA in a dose-and time-dependent fashion, despite its ability to induce other CC- or CXC chemokines. MIPs mRNA down-regulation was associated with decreased intracellular chemokine expression and secretion and was dependent on both mRNA destabilization and gene transcription inhibition. Moreover, IFNgamma inhibitory effects were stimulus-specific because MIPs induction by PA was either unaffected or increased by the anti-inflammatory cytokines, IL-10 and IL-4, or the pro-inflammatory stimulus, LPS, respectively. In contrast, we found that IFNgamma increased CCR5 basal expression, whereas PA down-regulated both constitutive and IFNgamma-induced CCR5 mRNA and protein levels. These results demonstrate that IFNgamma and PA have reciprocal effects on the production of MIPs chemokines and the expression of their receptor. The concerted action of IFNgamma and PA on MIP-1alpha/beta chemokine/receptor system is likely to be of pathophysiological significance and to represent an important regulatory mechanism for leukocyte recruitment and distribution into damaged tissues during inflammatory responses.

Different chemokines are expressed in human arthritic bone biopsies: IFN-gamma and IL-6 differently modulate IL-8, MCP-1 and rantes production by arthritic osteoblasts

In the present study we analyse chemokine expression in the remodelling of subchondral bone in arthritis patients. Trabecular bone biopsies were tested by immunohistochemistry to identify interleukin (IL)-8, GRO-alpha, MCP-1, RANTES, MIP-1alpha and MIP-1beta expression. Subsequently, we evaluated by immunoassay the effect of interferon (IFN)-gamma and IL-6 on chemokine production by osteoarthritis (OA), rheumatoid arthritis (RA) and post-traumatic (PT) patients' isolated osteoblasts (OB). OB constitutively produced in situ IL-8, GRO-alpha, MCP-1, RANTES and MIP-1alpha. MIP-1beta was positive only in mononuclear cells. In RA many of these chemokines were also produced by mononuclear cells. IFN-gamma significantly down-regulated IL-8 and up-regulated MCP-1 produced by OB from all patients tested, whereas it did not affect the other chemokines analysed. Moreover, IFN-gamma reduced IL-1beta-stimulated IL-8 production but significantly increased both MCP-1 and RANTES. Interestingly, IL-6 significantly downregulated IFN-gamma-induced MCP-1 production, that was significantly lower in OA compared to RA patients. OB expressed chemokines both in vivo and in vitro suggesting that these cells are primary effectors in the bone capable of regulating autocrine/paracrine circuits that affect bone remodelling in these diseases.

Interleukin-6 and interferon-gamma gene polymorphisms in the development of bronchiolitis obliterans syndrome after lung transplantation

BACKGROUND

A number of genetic polymorphisms have been shown to regulate the production and secretion of tumor necrosis factor (TNF)-alpha, transforming growth factor (TGF)-beta1, interferon (IFN)-gamma, interleukin (IL)-6, and IL-10. Several of these genetic polymorphisms have been shown to be associated with either acute or chronic rejection of kidney, liver, and heart allografts and with development of allograft fibrosis after lung transplantation. The aim of this study was to assess the effect of these genetic polymorphisms on the development of bronchiolitis obliterans syndrome (BOS) after lung transplantation.

METHODS

Genetic polymorphisms were detected by means of polymerase chain reaction in 93 lung allograft recipients for functional polymorphisms in the TNF-alpha (-308), TGF-beta1 (+869 and +915), IL-6 (-174), IFN-gamma (+874), and IL-10 (-1082, -819, and -592) genes. Then, a correlation between BOS development and the presence of these cytokine genotypes was determined using Kaplan-Meier actuarial analysis.

RESULTS

A significant correlation was detected between the presence of high-expression polymorphisms of the IL-6 and IFN-gamma genes and BOS development after lung transplantation (P =0.045 and 0.039, respectively). Also, patients with high-expression polymorphisms in both genes developed BOS significantly earlier than patients with low-expression polymorphisms in one or both genes, suggesting a synergistic effect of the alleles during BOS pathogenesis (P =0.016). No correlation was detected between polymorphisms of the TNF-alpha, TGF-beta1, and IL-10 genes and development of BOS after lung transplantation.

CONCLUSIONS

The presence of high-expression polymorphisms at position -174 of the IL-6 gene and position +874 of the IFN-gamma gene significantly increases the risk for BOS development after lung transplantation.

Significance of chemokines and soluble CD40 ligand in patients with autoimmune thrombocytopenic purpura

We investigated the levels of various chemokines and soluble CD40L (sCD40L) in ITP patients, in order to determine the influence of CD40-CD40L interaction on the pathogenesis of ITP. We found increases in MCP-1 and RANTES levels in ITP patients compared with those in healthy individuals. Thirty-eight of the 65 ITP patients (58.5%) had elevated levels of sCD40L. We found significant decreases in platelet counts in sCD40L-positive ITP patients. Although the sCD40L level did not differ significantly between the control and nonimmune thrombocytopenia groups, but among ITP patients. sCD40L level was significantly higher in those with untreated ITP than in those with treated ITP. In addition, significant increases in RANTES, MCP-1, sCD14, and sP-selectin levels were observed in sCD40L-positive ITP patients, although sE-selectin levels were not increased in such patients. For other factors examined, however, there were no differences in level between sCD40L-positive and -negative ITP patients. These findings suggests that there are two groups of ITP patients, one with elevated and one with normal of sCD40L. ITP cases in which sCD40L was increased appeared to involve changes in platelet counts and monocyte activation. The pathogenesis of ITP may in some patients include alterations of the CD40/CD40L pathway.

Antagonistic effect of picolinic acid and interferon-gamma on macrophage inflammatory protein-1alpha/beta production

The L-tryptophan catabolite, picolinic acid (PA), is an activator of macrophage effector functions and an inducer of macrophage inflammatory protein-1alpha (MIP-1alpha) and -1beta (MIPs). We have investigated the regulation of PA-induced MIPs production in mouse macrophages. We demonstrated a dose- and time-dependent downregulation of MIPs mRNA by the Th1 cytokine, IFN-gamma, that was associated with inhibition of intracellular chemokine production and secretion. This effect was IFN-gamma-specific because MIPs induction was unaffected by the Th2 cytokines, IL-10 and IL-4, or the proinflammatory stimulus, LPS. Moreover, MIPs downregulation by IFN-gamma was dependent on both mRNA destabilization and gene transcription inhibition. These results demonstrate that MIP-1alpha/beta production by macrophages is a tightly regulated process resulting from the interaction between inhibitory stimuli derived from the immune system and stimulatory signals of non-immunologic origin. The antagonistic effect of PA and IFN-gamma on MIPs production may be important for the regulation of the inflammatory responses in vivo.

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.

Sensitization of IFN-gamma Jak-STAT signaling during macrophage activation

A general paradigm in signal transduction is ligand-induced feedback inhibition and the desensitization of signaling. We found that subthreshold concentrations of interferon-gamma (IFN-gamma), which did not activate macrophages, increased their sensitivity to subsequent IFN-gamma stimulation; this resulted in increased signal transducer and activator of transcription 1 (STAT1) activation and increased IFN-gamma#150;dependent gene activation. Sensitization of IFN-gamma signaling was mediated by the induction of STAT1 expression by low doses of IFN-gamma that did not effectively induce feedback inhibition. IFN-gamma signaling was sensitized in vivo after IFN-gamma injection, and STAT1 expression was increased after injection of lipopolysaccharide and in rheumatoid arthritis synovial cells. These results identify a mechanism that sensitizes macrophages to low concentrations of IFN-gamma and regulates IFN-gamma responses in acute and chronic inflammation.

Effects of dietary omega3 and omega6 lipids and vitamin E on chemokine levels in autoimmune-prone MRL/MpJ-lpr/lpr mice

Elevated levels of chemokines, such as Regulated upon Activation, Normal T cell Expressed and Secreted (RANTES), Monocyte Chemotactic Protein-1 (MCP-1), Macrophage Inflammatory Protein-1alpha (MIP-1alpha), and Macrophage Inflammatory Protein-1beta (MIP-1beta) have been found in rheumatoid arthritis (RA) and juvenile arthritis (JA), and they may be associated with the pathogenesis of these diseases. These chemokines are implicated in the migration of specific leukocytes into the joints. Omega-3 (omega3) fatty acid rich-fish oil (FO) and vitamin E may delay the progress of certain autoimmune diseases. The present study was designed to understand the effects of dietary lipids (omega-6 and omega-3 fatty acids) and vitamin E on the production of chemokines in autoimmune-prone MRL/lpr (a mouse model for RA) and congenic control MRL/++ mice. The MRL mice were fed for 4.5 months omega-6 and omega-3 diets that varied in lipid sources (corn oil; CO and fish oil; FO) and vitamin E levels (269 I.U./kg and 694 I.U./kg diet). Spleen cells were isolated and cultured aseptically in the presence of PHA for 48 h at 37 degrees C and the levels of chemokines (RANTES, JE/MCP-1 and MIP-1alpha) were determined in the cell-free supernatants. The levels of RANTES and JE/MCP-1 were significantly higher in MRL/lpr mice compared to MRL/++ mice. The FO had differential effect on RANTES and MCP-1 production by spleen cells. The production of RANTES and JE/MCP-1 by spleen cells in mice fed the FO diets was significantly lower than in mice fed the CO diets (p < 0.0001). The levels of vitamin E did not affect the production of RANTES and JE/MCP-1. The levels of vitamin E had a significant effect on MIP-1alpha as the spleen cells of mice fed diets containing 694 IU/kg diet of vitamin E produced significantly higher levels of MIP-1alpha compared to the group of mice fed the diets containing 269 IU of vitamin E (p < 0.0001). The data obtained from this study in MRL/lpr and MRL/++ mice suggest that FO diets containing omega-3 fatty acids are beneficial in decreasing the levels of certain pro-inflammatory chemokines (RANTES and MCP-1) thereby delaying the onset of and severity of autoimmune symptoms in MRL/lpr mouse model.

The importance of IL-1 beta and TNF-alpha, and the noninvolvement of IL-6, in the development of monoclonal antibody-induced arthritis

Injection of anti-type II collagen Ab and LPS induces arthritis in mice. The levels of IL-1 beta, IL-6, and chemokines (macrophage inflammatory protein (MIP)-1 alpha, MIP-2, and monocyte chemoattractant protein-1) in the hind paws increased with the onset of arthritis and correlated highly with arthritis scores. The level of TNF-alpha was also elevated, but only transiently. Quantitative real-time PCR analysis revealed increases in cytokine and chemokine mRNA. To elucidate the contribution of inflammatory cytokines and chemokines in arthritis development more directly, recombinant proteins, neutralizing Abs, and knockout mice were used. The injection of rIL-1 beta or TNF-alpha, but not IL-6 or chemokines, induced arthritis when mice were i.v. preinjected with anti-type II collagen Ab. However, a single injection of recombinant cytokines or chemokines into the hind paws did not induce swelling. Arthritis development was inhibited by neutralizing Ab against IL-1 beta, TNF-alpha, or MIP-1 alpha. In contrast, the inhibitory effect by anti-MIP-2 Ab was partial and, surprisingly, Abs to IL-6 and monocyte chemoattractant protein-1 showed no inhibitory effect. Furthermore, arthritis development in IL-1R(-/-) mice and TNFR(-/-) mice was not observed at all, but severe arthritis was developed in IL-6(-/-) mice. These results suggest that IL-1 beta and TNF-alpha play more crucial roles than IL-6 or chemokines in this model. Because arthritis was also developed in SCID mice, the development of arthritis in the Ab-induced mice model is due to a mechanism that does not involve T or B cells.

Association of platelet-derived microparticles with C-C chemokines on vascular complication in patients with acute myocardial infarction

The levels of platelet-derived microparticles (PDMPs), platelet activation markers (P-selectin, CD63, and PAC-1 on activated platelets), and C-C chemokines (monocyte chemotactic peptide [MCP]-1 and regulated on activation normally T-cell expressed and secreted [RANTES] were measured and compared in patients with acute myocardial infarction (AMI) or stable pectoris angina. These substances are thought to paricipate in the development of complications in patients with AMI. The percentage binding of anti-P-selectin, CD63, and PAC-1 antibody to platelets, and the levels of PDMPs (per 10(4) platelets) were higher in the patients with AMI than in those with stable pectoris angina (P-selectin, 23.1% +/- 2.1% vs. 10.3% +/- 1.2%, p < 0.001; CD63, 24.6% +/- 3.3% vs. 11.2% +/- 3.1%, p < 0.01; PAC-1, 14.1% +/- 1.7% vs. 9.3% +/- 2.1%, p < 0.05; PDMPs, 613 +/- 71 vs. 413 +/- 55, p < 0.01). There were no differences in platelet levels of GPIIb/IIIa and GPIb between groups. Levels of MCP-1 and RANTES were higher in the patients with AMI than in patients with stable pectoris angina (MCP-1, 430 +/- 35 vs. 265 +/- 23, p<0.01; RANTES, 175 +/- 32 vs. 88 +/- 29, p<0.001). The effects of percutaneous transluminal coronary angioplasty (PTCA) on the levels of these agents in patients with AMI were studied. Platelet activation markers were significantly decreased in patients with AMI after PTCA. RANTES level was also significantly decreased after treatment, but MCP-1 level was not changed. In addition, this tendency was clearer in STENT patients. These findings suggest that in patients with AMI PTCA, particularly STENT, may prevent the development of complications in which activated platelet and RANTES participate.