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Divergent regulation of cell surface protease expression in HL-60 cells differentiated into macrophages with granulocyte macrophage colony stimulating factor or neutrophils with retinoic acid.

Taking advantage of the recently demonstrated presence of N-aminopeptidases and the serine protease dipeptidyl aminopeptidase IV (DPP IV) at the surface of human myeloblastic HL-60 cells, the regulation of these protease activities in HL-60 cell differentiation has been assessed using combined spectrophotometric and flow cytometric assays. Addition of human recombinant granulocyte macrophage colony stimulating factor (rHu-GM-CSF) to HL-60 cells to induce differentiation into macrophages led to a time- and dose-dependent increase in both cell surface N-aminopeptidase and DPP IV activities. Protease up-regulation was due to an enhancement in cell surface protease number, associated with a slight rise in apparent affinities of the enzymes for their substrates. In contrast, in HL-60 cells induced to differentiate into neutrophils in the presence of retinoic acid, expression of cell surface N-aminopeptidases was almost completely abolished in a time- and dose-dependent fashion, and this down-regulation was accompanied by a weak but significant decrease in affinity. However, no noticeable difference was seen in serine DPP IV expression between retinoic acid-treated and untreated HL-60 cells. Retinoic acid treatment also reduced soluble protease activity in vitro indicating that down-regulation of membrane aminopeptidases was not due to their proteolytic clip. No modulation in the activity of any of the enzymes tested was seen with human recombinant tumor necrosis factor-alpha or retinol which do not induce HL-60 cell differentiation.(ABSTRACT TRUNCATED AT 250 WORDS)

Blood Cells↗

Effect of granulocyte-macrophage colony-stimulating factor on candidacidal activity of neutrophils, monocytes or monocyte-derived macrophages and synergy with fluconazole.

The effect of in-vitro granulocyte-macrophage colony-stimulating factor (GM-CSF) treatment of neutrophils, monocytes or monocyte-derived macrophages (MDM) on candidacidal activity was tested. Synergy of effector cells with fluconazole (FCZ) for enhanced killing was also investigated. Incubation of neutrophils with GM-CSF 0.67 microg/L plus Candida albicans Sh27 for 24 h significantly increased candidacidal activity (36% versus 74%). Synergy with FCZ for killing was also significantly increased from 93% to 97% when neutrophils were incubated with GM-CSF. Monocytes cultured with GM-CSF and C. albicans for 24 h had significantly increased fungistatic activity compared to controls and synergy with FCZ for killing was significantly enhanced from 40% to 59%. Monocytes cultured for 3 days with GM-CSF had increased fungistatic activity compared to control MDM and showed synergy with FCZ for significantly enhanced killing (46%) compared to control MDM (12%).

Antifungal Agents↗

Effect of macrophage colony-stimulating factor on anticryptococcal activity of bronchoalveolar macrophages: synergy with fluconazole for killing.

The anticryptococcal activity of murine bronchoalveolar macrophages (BAM) and their synergy with fluconazole (FCZ) was studied. BAM cultured with tissue culture medium for 48 to 72 h were fungicidal (24 to 39%) in a 3-h killing assay. However, net killing of Cryptococcus neoformans did not continue when culture time was extended to 24 h, although BAM were fungistatic (88 to 98%). Treatment with macrophage colony-stimulating factor (M-CSF; 5,000 U/ml, 48 h) did not significantly increase BAM killing of a low challenge dose in 3-h assays compared with control BAM. However, M-CSF-treated BAM were significantly more fungistatic against higher challenge doses in the 3-h assays. FCZ was not fungicidal at 5 micrograms/ml but was highly fungistatic (98 and 99% at 24 and 48 h, respectively). M-CSF-treated BAM acted synergistically with FCZ (2.5 micrograms/ml) for significantly greater killing than control BAM, 55% versus 20% and 96% versus 45% at 24 h and 48 h, respectively. Killing by M-CSF BAM and FCZ (5.0 micrograms/ml) was significantly (P < 0.01) greater than that by control BAM and FCZ at 48 h. These findings indicate an important collaborative role for BAM and FCZ in killing C. neoformans, and this is enhanced by M-CSF.

Animals↗

Differential induction of bone marrow macrophage proliferation by mycoplasmas involves granulocyte-macrophage colony-stimulating factor.

We have studied the ability of three different Mycoplasma species to induce proliferation of bone marrow-derived macrophages (BMM). We observed a significant mitogenic effect when BMM cells from BALB/c, DBA/2J, SJL, and C57BL/6 mice were incubated with membranes derived from Mycoplasma arginini or M. arthritidis but not when they were incubated with an equivalent amount of M. pulmonis membrane. We also determined that pretreatment of mycoplasma membrane preparations with papain eliminated the ability of these preparations to induce BMM proliferation. To determine whether these membrane fractions acted indirectly by stimulating the production of soluble factors known to stimulate proliferation of BMM cells, we performed blocking studies with antibodies directed against colony-stimulating factor 1 (CSF-1), interleukin-3 (IL-3), and granulocyte-macrophage colony-stimulating factor. Our results indicate that antibodies directed against either CSF-1 or IL-3 failed to block mycoplasma-initiated proliferation of BMM cells. However, when anti-GM-CSF was added to proliferative cultures at the time of initiation, we saw a dose-dependent reduction of mycoplasma-initiated proliferation. We conclude that the ability of mycoplasma membranes to initiate the proliferation of BMM is not shared by all species of mycoplasma and that it involves the production of GM-CSF by an as yet undetermined cell.

Animals↗

Lactoferrin peptide increases the survival of Candida albicans-inoculated mice by upregulating neutrophil and macrophage functions, especially in combination with amphotericin B and granulocyte-macrophage colony-stimulating factor.

To develop a new strategy to control candidiasis, we examined in vivo the anticandidal effects of a synthetic lactoferrin peptide, FKCRRWQWRM (peptide 2) and the peptide that mimics it, FKARRWQWRM (peptide 2'). Although all mice that underwent intraperitoneal injection of 5 x 10(8) Candida cells with or without peptide 2' died within 8 or 7 days, respectively, the survival times of mice treated with 5 to 100 microg of intravenous peptide 2 per day for 5 days after the candidal inoculation were prolonged between 8.4 +/- 2.9 and 22.4 +/- 3.6 days, depending on the dose of peptide 2. The prolongation of survival by peptide 2 was also observed in mice that were infected with 1.0 x 10(9) Candida albicans cells (3.2 +/- 1.3 days in control mice versus 8.2 +/- 2.4 days in the mice injected with 10 microg of peptide 2 per day). In the high-dose inoculation, a combination of peptide 2 (10 microg/day) with amphotericin B (0.1 microg/day) and granulocyte-macrophage colony-stimulating factor (GM-CSF) (0.1 microg/day) brought prolonged survival. With a combination of these agents, 60% of the mice were alive for more than 22 days. Correspondingly, peptide 2 activated phagocytes inducing inducible NO synthase and the expression of p47(phox) and p67(phox), and peptide 2 increased phagocyte Candida-killing activities up to 1.5-fold of the control levels upregulating the generation of superoxide, lactoferrin, and defensin from neutrophils and macrophages. These findings indicated that the anticandidal effects of peptide 2 depend not only on the direct Candida cell growth-inhibitory activity, but also on the phagocytes' upregulatory activity, and that combinations of peptide 2 with GM-CSF and antifungal drugs will help in the development of new strategies for control of candidiasis.

Amphotericin B↗

virB-Mediated survival of Brucella abortus in mice and macrophages is independent of a functional inducible nitric oxide synthase or NADPH oxidase in macrophages.

The Brucella abortus virB locus is required for establishing chronic infection in the mouse. Using in vitro and in vivo models, we investigated whether virB is involved in evasion of the bactericidal activity of NADPH oxidase and the inducible nitric oxide synthase (iNOS) in macrophages. Elimination of NADPH oxidase or iNOS activity in macrophages in vitro increased recovery of wild-type B. abortus but not recovery of a virB mutant. In mice lacking either NADPH oxidase or iNOS, however, B. abortus infected and persisted to the same extent as it did in congenic C57BL/6 mice up until 60 days postinfection, suggesting that these host defense mechanisms are not critical for limiting bacterial growth in the mouse. A virB mutant did not exhibit increased survival in either of the knockout mouse strains, indicating that this locus does not contribute to evasion of nitrosative or oxidative killing mechanisms in vivo.

Animals↗

Macrophages infected with cytopathic bovine viral diarrhea virus release a factor(s) capable of priming uninfected macrophages for activation-induced apoptosis.

Bovine bone marrow-derived macrophages infected with the cytopathic biotype of bovine viral diarrhea virus released an antiviral activity into the supernatant which was tentatively characterized as type I interferon because of its physicochemical properties. Such supernatants primed both infected and uninfected macrophages for decreased nitric oxide production and apoptosis in response to lipopolysaccharide. This finding strongly suggests a role of this pathway in the pathogenesis of mucosal disease, a lethal form of infection with cytopathic bovine viral diarrhea virus in which the principal lesions are located in the oral cavity and the gastrointestinal tract, which are known to contain a high concentration of endotoxin.

Animals↗

Hoxa9 immortalizes a granulocyte-macrophage colony-stimulating factor-dependent promyelocyte capable of biphenotypic differentiation to neutrophils or macrophages, independent of enforced meis expression.

The genes encoding Hoxa9 and Meis1 are transcriptionally coactivated in a subset of acute myeloid leukemia (AML) in mice. In marrow reconstitution experiments, coexpression of both genes produces rapid AML, while neither gene alone generates overt leukemia. Although Hoxa9 and Meis1 can bind DNA as heterodimers, both can also heterodimerize with Pbx proteins. Thus, while their coactivation may result from the necessity to bind promoters as heterodimers, it may also result from the necessity of altering independent biochemical pathways that cooperate to generate AML, either as monomers or as heterodimers with Pbx proteins. Here we demonstrate that constitutive expression of Hoxa9 in primary murine marrow immortalizes a late myelomonocytic progenitor, preventing it from executing terminal differentiation to granulocytes or monocytes in the presence of granulocyte-macrophage colony-stimulating factor (GM-CSF) or interleukin-3. This immortalized phenotype is achieved in the absence of endogenous or exogenous Meis gene expression. The Hoxa9-immortalized progenitor exhibited a promyelocytic transcriptional profile, expressing PU.1, AML1, c-Myb, C/EBP alpha, and C/EBP epsilon as well as their target genes, the receptors for GM-CSF, G-CSF, and M-CSF and the primary granule proteins myeloperoxidase and neutrophil elastase. G-CSF obviated the differentiation block of Hoxa9, inducing neutrophilic differentiation with accompanying expression of neutrophil gelatinase B and upregulation of gp91phox. M-CSF also obviated the differentiation block, inducing monocytic differentiation with accompanying expression of the macrophage acetyl-low-density lipoprotein scavenger receptor and F4/80 antigen. Versions of Hoxa9 lacking the ANWL Pbx interaction motif (PIM) also immortalized a promyelocytic progenitor with intrinsic biphenotypic differentiation potential. Therefore, Hoxa9 evokes a cytokine-selective block in differentiation by a mechanism that does not require Meis gene expression or interaction with Pbx through the PIM.

Animals↗

Corticosteroid inhibition of macrophage inflammatory protein-1 alpha in human monocytes and alveolar macrophages.

One of the major inducible cytokines secreted by mononuclear phagocytes is macrophage inflammatory protein 1 (MIP-1), which consists of two homologous polypeptides, MIP-1 alpha and MIP-1 beta. MIP-1 alpha possesses chemotactic and stimulatory activities for lymphocytes, eosinophils, and monocytes and may play a role in various pulmonary inflammatory conditions. We investigated the expression and release of MIP-1 alpha from human peripheral blood monocytes (PBM) and alveolar macrophages (AM) after stimulation with lipopolysaccharide (LPS), interleukin-1 beta (IL-1 beta), tumor necrosis factor-alpha, and interferon-gamma and the inhibitory effects of corticosteroids. LPS and IL-1 beta only enhanced MIP-1 alpha mRNA and protein in a dose- and time-dependent fashion. Dexamethasone (10(-9) to 10(-4) M) inhibited the basal and induced production and expression of MIP-1 alpha. In PBM, dexamethasone (10(-6) M) reduced LPS- and IL-1 beta-stimulated production of MIP-1 alpha protein by 50 and 63%, respectively, maximally at 24 h, whereas the inhibition of mRNA expression occurred maximally at 4 h. Similar trends were observed for AM. MIP-1 alpha mRNA decay was only slightly decreased in the presence of dexamethasone. Inhibition of LPS-induced MIP-1 alpha mRNA by dexamethasone was attenuated by the protein synthesis inhibitor cycloheximide, indicating the involvement of a protein intermediate. Corticosteroids are a potent inhibitor of IL-1 beta- and LPS-induced expression of MIP-1 alpha through mechanisms involving mainly inhibition of transcription and to a minor degree by reducing mRNA stability. Corticosteroids may be effective anti-inflammatory agents by preventing the expression of chemokines such as MIP-1 alpha.

Base Sequence↗

Macrophage phenotype in mice deficient in both macrophage-colony-stimulating factor (op) and apolipoprotein E.

Mice deficient in both macrophage-colony-stimulating factor (M-CSF, op) and apolipoprotein E (apoE) have elevated cholesterol levels but are protected from atherosclerosis. To assess the contribution of macrophage (Mphi) phenotypic heterogeneity and scavenger receptor (SR-A) expression to this seeming paradox, we characterized the Mphi phenotype by immunohistochemistry in these animals. Lesion size was determined in animals fed a chow or Western-type diet, and lipoprotein clearance studies were performed in vivo. Op0/E0 mice have fourfold smaller aortic root lesions than op2/E0 animals despite 2.5-fold higher total plasma cholesterol levels. Mphis in atherosclerotic lesions of op2/E0 mice constitute a predominantly recruited and M-CSF-dependent population. In addition, Mphis in different locations in plaques show phenotypic heterogeneity. SR-A expression in op0/E0 mice is reduced in proportion to the decrease in Mphi numbers, and M-CSF is thus not an essential requirement for SR-A expression in vivo. M-CSF-deficient mice degrade injected AcLDL , showing an adequate level of SR-A activity present in vivo. In contrast, beta-VLDL clearance in op0/E0 mice is decreased, implicating monocytes/Mphis in its catabolism. There is prominent lipid accumulation in op2/E0 Kupffer cells and hepatocytes but not in M-CSF-independent Kupffer Mphis from op0/E0 mice. SR-A, while abundantly expressed on both Kupffer cells and sinusoidal endothelial cells in op2/E0 mice, remains mainly on sinusoidal endothelial cells in op0/E0 mice. This may explain preservation of SR-A activity in these animals. Our findings clearly illustrate the importance of both M-CSF and M-CSF-dependent monocytes/Mphis in maintaining cholesterol homeostasis and in atherogenesis.

Animals↗

Phenotypic analysis of alveolar macrophages and monocytes in allergic airway inflammation. I. Evidence for activation of alveolar macrophages, but not peripheral blood monocytes, in subjects with allergic rhinitis and asthma.

Macrophages and monocytes play important proinflammatory roles in allergic inflammation. We hypothesized that these cells would express an activated phenotype in allergic disease of the airways. We therefore compared the expression of 17 activation markers on the surface of alveolar macrophages (AM) and peripheral blood monocytes (PBM) in 13 subjects with asymptomatic allergic asthma (AA), nine subjects with asymptomatic allergic rhinitis (AR), and 11 nonallergic (N). AM were obtained by BAL, and PBM were simultaneously obtained by phlebotomy; both were analyzed for expression of surface markers using a new two-color flow cytometry method that essentially eliminates background autofluorescence. The proportions of AM in BAL fluid from AA, AR, and N subjects were 84 +/- 2, 85 +/- 4, and 91 +/- 1%, respectively; viability always exceeded 92%. Expression of eight markers (CD16, CD18, CD32, CD44, CD71, HLA Class I, HLA DR, and HLA DQ) was significantly (p < 0.05) higher on AM of AA than on N; expression of six markers (CD11a, CD16, CD18, CD71, HLA Class I, and HLA DR) was higher on AM of AR than on N, with differences in CD44 levels approaching statistical significance (p = 0.07). Expression of one marker, CD44, was significantly higher on AM of AA than on those of AR, with differences in HLA Class I levels approaching statistical significance (p = 0.07). In contrast, no significant differences were found among the three groups in the expression in eight other markers (CD11b, CD14, CD23, CD29, CD33, CD35, CD63, and CD64). Finally, similar analysis of PBM from these same subjects failed to find any difference between the three groups in any of the 17 activation markers studied. These data suggest that AM are activated in allergic respiratory diseases, and that levels of HLA Class I and CD44 on AM are altered during allergic inflammation in the upper and lower airways.

Adult↗

Identification of an alveolar macrophage-derived activity in bronchial asthma that enhances leukotriene C4 generation by human eosinophils stimulated by ionophore A23187 as a granulocyte-macrophage colony-stimulating factor.

Incubation of eosinophils (EOS) with alveolar macrophage (AM) supernatants isolated from asthmatic subjects followed by stimulation with the calcium ionophore A23187 resulted in enhancement of the capacity of EOS to elaborate leukotriene C4 (LTC4) (mean enhancement 169 +/- 37%, n = 31). Pretreatment of EOS with AM supernatants derived from normal individuals did not enhance LTC4 generation as compared with control medium. Enhancement was maximal when EOS were preincubated with a 1:6 dilution of AM supernatants for 5 min at 37 degrees C and were then stimulated with 5 microM A23187 for 15 min. Separation of AM supernatants by size-exclusion HPLC using a TSK G3000 SW column resulted in a peak of enhancing activity with an estimated molecular mass of approximately 30,000 D. Further purification by anion exchange HPLC using a TSK DEAE 5PW column (pH 7.4) resolved the activity into a minor peak at 0.17 M NaCl and a major peak at 0.2 M NaCl. The activities were distinct from interleukin-1 and tumor necrosis factor. Resolution of the major peak of activity by reverse-phase HPLC using a C18 spherisorb ODS column and a slope gradient of 0 to 100% acetonitrile/0.1% trifluoroacetic acid demonstrated a single peak of activity that eluted at 41% acetonitrile. The enhancing activity was sensitive to trypsin and heat and was neutralized by a specific antibody to granulocyte-macrophage colony-stimulating factor (GM-CSF). Pretreatment of EOS with recombinant GM-CSF primed the cells for enhanced LTC4 generation following subsequent stimulation with A23187. GM-CSF may play a role in the amplification of the eosinophilic inflammation in asthmatic airways.

Adolescent↗

Isolation and partial characterization of subpopulations of alveolar macrophages, granulocytes, and highly enriched interstitial macrophages from rat lung.

The contribution of interstitial macrophages (IM) to lung defense, homeostasis, and pathophysiology is for the most part unknown. Studies on this cell type are difficult because they are not readily accessible in large numbers or in high purity. In the present work, various nonenzymatic and enzymatic methods were compared with the aim of isolating and characterizing pure populations of lung IM. The results of our studies demonstrate that most procedures currently used to isolate IM yield subpopulations of alveolar macrophages (AM) or IM highly contaminated by AM and granulocytes. We found that lavage of the lung yielded only one half of the total AM present in the tissue. The remainder of the AM could only be obtained by extensive washing of cut and disaggregated lung tissue, which is considered by some investigators to be an effective procedure for IM isolation. According to our results, cells recovered by lavage and washing of cut and disaggregated lung tissue were morphologically and histochemically identical, were strongly positive for nonspecific esterase, highly phagocytic, and appeared to represent subpopulations of AM with apparently varying degrees of adherence to the alveolar walls. We also found that IM could be obtained in high purity by sequential digestion of the remaining lung tissue with 60 and 175 IU/ml of collagenase followed by selective adherence. Digestion of the tissue with 60 IU/ml of collagenase resulted in a highly enriched population of granulocytes and also reduced their contamination in the IM population. The resulting IM were distinct from AM by morphology and histochemistry. Like AM, these cells displayed Fc receptor-mediated phagocytosis.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

Carbon monoxide modulates endotoxin-induced production of granulocyte macrophage colony-stimulating factor in macrophages.

The stress-inducible gene heme oxygenase-1 (HO-1) provides protection against oxidative stress. Although the mechanisms by which HO-1 exerts its cytoprotection are not clearly understood, it has been speculated that carbon monoxide (CO), a catalytic byproduct following heme catabolism by HO-1, may mediate cellular cytoprotection via its anti-inflammatory properties. Granulocyte macrophage colony-stimulating factor (GM-CSF) is a potent cytokine generated in response to bacterial endotoxin (lipopolysaccharide [LPS]) to stimulate proliferation, maturation, and effector functions of leukocytes, contributing to the proinflammatory responses to LPS. We hypothesized that HO-1 and/or CO could regulate the expression and production of GM-CSF. HO-1 overexpression, as well as exposure to a low concentration of CO, inhibited LPS-induced GM-CSF production in macrophages. Furthermore, CO inhibited LPS-induced GM-CSF induction via inhibition in the activation of the transcription factor NF-kappaB. CO inhibited LPS-induced activation of NF-kappaB, which has been shown to regulate GM-CSF transcription, by preventing the phosphorylation and degradation of the regulatory subunit IkappaB-alpha. These data raise the intriguing possibility that CO at low concentrations may play an important role in inflammatory disease states and thus has potential therapeutic implications.

Animals↗

Transcriptional rates of granulocyte-macrophage colony-stimulating factor, granulocyte colony-stimulating factor, interleukin-3, and macrophage colony-stimulating factor genes in activated cord versus adult mononuclear cells: alteration in cytokine expression may be secondary to posttranscriptional instability.

We have previously demonstrated that protein production and mRNA expression of granulocyte-macrophage colony-stimulating factor (GM-CSF), granulocyte colony-stimulating factor (G-CSF), and IL-3 are decreased in activated mononuclear cells (MNC) from human umbilical cord compared with adult peripheral blood. Reduced production of these colony-stimulating factors (CSF) during states of increased demand, as occurs during overwhelming bacterial infection, may play a role in the pathogenesis of neutropenia and thrombocytopenia in the newborn. To determine whether the reduced mRNA expression and CSF production from activated cord MNC is secondary to the decreased transcriptional activity of the corresponding genes, we determined the transcriptional rate of GM-CSF, G-CSF, IL-3, and M-CSF by nuclear run-on assays. Cord and adult MNC were isolated by Ficoll-Hypaque density centrifugation. A total of 10(8) MNC from cord and adult blood were stimulated as follows: GM-CSF and G-CSF [32 nmol/L phorbol-12-myristate-6-acetate (20 micrograms/L) + 2 mg/L phytohemagglutinin for 6 h]; IL-3 [32 nmol/L phorbol-12-myristate-6-acetate (20 micrograms/L) + 0.5 mumol/L A 23187 for 6 h]; and macrophage CSF (2 micrograms/L recombinant human GM-CSF for 24 h). The nuclei from unstimulated and stimulated cells were isolated and labeled with 32P-uridine triphosphate. Newly elongated 32P-labeled RNA transcripts were hybridized to slot blots of CSF DNA. To minimize cross hybridization artifacts, short fragments (0.5-1.0 kb) of cDNA were used.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

Gaucher cells demonstrate a distinct macrophage phenotype and resemble alternatively activated macrophages.

Although the existence of anti-inflammatory alternatively activated macrophages (aamphi) has been accepted widely based on in vitro studies, their in vivo location, phenotype, and function still are debated. Gaucher disease (GD) is caused by a genetic deficiency in the lysosomal enzyme glucocerebrosidase and is characterized by accumulation of glycosphingolipids in so-called Gaucher cells (GCs). By using immunohistochemical analysis, we investigated whether this results in an aamphi phenotype. GCs are macrophage-like cells, expressing acid phosphatase, CD68, CD14, and HLA class II, but not CD11b, CD40, or dendritic cell markers. GCs show infrequent immunoreactivity for mannose receptor GCs did not express proinflammatory cytokines such as tumor necrosis factor alpha and monocyte chemoattractant protein 1, but did express the aamphi markers CD163, CCL18, and interleukin-1 receptor antagonist. Furthermore, CD36 and signal receptor protein alpha, involved in lipid uptake, also were observed on GCs. Thus, GCs represent a distinctive population of myeloid cells that resemble aamphi but differ from previously described in vitro aamphi.

Biomarkers↗

Macrophage migration inhibitory factor deficiency attenuates macrophage recruitment, glomerulonephritis, and lethality in MRL/lpr mice.

Systemic lupus erythematosus (SLE) is a serious systemic autoimmune disease of unknown etiology. Macrophage migration inhibitory factor (MIF) is a proinflammatory cytokine that is operative in innate and adaptive immunity and important in immune-mediated diseases such as rheumatoid arthritis and atherosclerosis. The functional relevance of MIF in systemic autoimmune diseases such as SLE is unknown. Using the lupus-prone MRL/lpr mice, we aim to examine the expression and function of MIF in this murine model of systemic autoimmune disease. These experiments revealed that renal MIF expression was significantly higher in MRL/lpr mice compared with nondiseased control mice (MRL/MpJ), and MIF was also markedly up-regulated in skin lesions of MRL/lpr mice. To examine the effect of MIF on development of systemic autoimmune disease, we generated MRL/lpr mice with a targeted disruption of the MIF gene (MIF(-/-)MRL/lpr), and compared their disease manifestations to MIF(+/+)MRL/lpr littermates. MIF(-/-)MRL/lpr mice exhibited significantly prolonged survival, and reduced renal and skin manifestations of SLE. These effects occurred in the absence of major changes in T and B cell markers or alterations in autoantibody production. In contrast, renal macrophage recruitment and glomerular injury were significantly reduced in MIF(-/-)MRL/lpr mice, and this was associated with reduction in the monocyte chemokine MCP-1. Taken together, these data suggest MIF as a critical effector of organ injury in SLE.

Animals↗