Macrophage Inflammatory Protein-1α Expression Research Articles

Genetically predicted circulating levels of cytokines and the risk of oral cavity and pharyngeal cancer: a bidirectional mendelian-randomization study.

Background: Epidemiological research has established associations between various inflammatory cytokines and the occurrence of oral cancer and oropharyngeal cancer (OCPC). We performed a Mendelian randomization (MR) analysis to systematically investigate the causal relationship between inflammatory cytokines and OCPC. Methods: We performed a bidirectional two-sample MR analysis using OCPC from 12 studies (6,034 cases and 6,585 controls) and genome-wide association study (GWAS) results for 41 serum cytokines from 8,293 Finns, respectively. Inverse variance weighting was used as the primary MR method and four additional MR methods (MR Egger, Weighted median, Simple mode, Weighted mode) were used to examine genetic associations between inflammatory traits and OCPC, and Cochran's Q test, MR-Egger intercept, leave-one-out analysis, funnel plot, and multivariate MR (MVMR) analysis were used to assess the MR results. Results: The results suggested a potential association between high gene expression of Macrophage inflammatory protein-1α (MIP1α/CCL3) and an increased risk of OCPC (Odds Ratio (OR): 1.71, 95% Confidence Interval (CI): 1.09-2.68, p = 0.019). Increasing the expression levels of the interleukin-7 (IL-7) gene by 1 standard deviation reduced the risk of OCPC (OR: 0.64, 95%CI: 0.48-0.86, p = 0.003). In addition, multivariate Mendelian randomization analysis also showed the same results (MIP1α/CCL3, OR: 1.002, 95% CI: 0.919-1.092, p = 0.044; IL-7, OR: 0.997, 95% CI: 0.994-0.999, p = 0.011). Conversely, there was a positive correlation between genetic susceptibility to OCPC and an increase in Interleukin-4 (IL-4) (OR: 1.04, 95%CI: 1.00-1.08, p = 0.027). Conclusion: Our study systematically assessed the association between inflammatory cytokines and the risk of OCPC. We identified two upstream regulatory factors (IL-7 and CCL3) and one downstream effector factor (IL-4) that were associated with OCPC, offering potential avenues for the development of novel treatments.

Chromium Nanoparticles Improve Macrophage and T Cell Infiltration for Cancer Immunotherapy

Immune checkpoint blockade has been regarded as a highly promising cancer immunotherapy approach. However, inefficient immune cell infiltration and the immunosuppressive tumor microenvironment (TME) remain significant causes of low clinical response rates. Here, we identified that trivalent chromium irons (Cr3+) could enhance tumor infiltration of immune cells including M1-type tumor-associated macrophages and CD8+ T cells. Mechanistically, this effect is dependent on the expression of macrophage inflammatory protein-1α (MIP-1α) and the PI3K/Akt/mTOR pathway. Moreover, the Cr-based nanoparticles (Cr NPs) exhibited superior photothermal properties under near-infrared laser irradiation, showing great potential in transforming “cold” tumors into “hot” ones. In combination with the PD-1/PD-L1 pathway inhibitor, we demonstrated that the Cr NPs significantly improved anticancer efficacy in mouse models of hepatoma and melanoma by increasing antitumor immune cell infiltration and relieving immunosuppressive TME. Overall, the Cr NPs offer a new dual-functional platform for local and systemic cancer treatments, paving the way toward cancer photometalloimmunotherapy.

Adiponectin rescues the newborn rat lung from lipopolysaccharide (LPS)‐induced inflammation and injury

IntroductionPreterm infants born during the canalicular and saccular stages of lung development are at high risk for lung injury from oxidative stress and inflammation. Low adipose tissue mass is associated with low serum levels of protective anti‐inflammatory and anti‐oxidative adipokines, such as adiponectin (APN). The modulatory role of APN on inflammatory cytokines and tissue remodeling has unveiled APN as a novel therapeutic target for developmental lung pathologies. We have previously shown that prophylactic administration of exogenous APN protects the newborn rat from LPS‐induced lung injury. In this study, we investigate the ability for systemic APN given 20 hours after LPS aspiration to reverse lung injury in newborn rats.MethodsSprague‐Dawley rats at postnatal day (PND) 4 were treated with 5 mg/kg intrapharyngeal (IPh) LPS or saline; 20 hours later, 2 mg/kg recombinant APN (rAPN) or equal volume saline was administered intraperitoneally (IP). The three treatment groups included: rats exposed to LPS (IPh)/rAPN (IP), LPS (IPh)/saline (IP) and saline (IPh)/saline (IP). Lungs were harvested 6 hours after administration of rAPN and processed for gene (qPCR) and protein (SDS‐PAGE Western blot) expression. In another cohort of PND4 rats, rAPN was administered at 20 and 44 hours, with lungs removed and assayed for histopathology with haemotoxylin and eosin staining 72 hours after LPS. n=4 in each treatment group for gene/protein expression and histopathology.ResultsDifferences were observed in gene and protein expression between treatment groups (ANOVA, p<0.05). In animals treated with IP rAPN 20 hours after IPh LPS, mRNA expression of macrophage inflammatory protein‐1α (MIP‐1α), monocyte chemoattractant protein‐1 (MCP‐1), IL‐1β, IL‐6, and IL‐10 was reduced 7‐, 8‐, 3.6‐, 1.6‐ and 13‐fold, respectively, relative to saline treatment. Protein expression of tumor necrosis factor α (TNF‐α), IL‐1β and IL‐10 was also relatively reduced in rAPN treated rats. No change was detected in the mRNA expression of TNF‐α, or in the protein expression of IL‐6. Lungs treated with rAPN had a marked reduction in histopathological changes relative to saline‐treated controls.ConclusionsOur novel in vivo study demonstrates that beyond the preventative role of systemic APN in neonatal lung injury, APN can also attenuate previously induced acute, inflammatory lung injury. We speculate that increasing serum APN levels in preterm infants might protect from acute and chronic inflammatory lung injury.Support or Funding InformationWomen’s Auxiliary Board at SickKids

C-Jun Is Required for Nuclear Factor-κB-Dependent, LPS-Stimulated Fos-Related Antigen-1 Transcription in Alveolar Macrophages.

Previously, we have reported that Fos-related antigen-1 (Fra-1) transcription factor promotes LPS-induced acute lung injury and mortality, and that LPS-induced Fra-1 expression in the lung occurs predominantly in alveolar macrophages. Nuclear factor-κB (NF-κB) and c-Jun transcription factors play key roles in modulating inflammatory and immune responses induced by infectious and non-infectious insults. Here, we report that NF-κB and c-Jun coregulate Fra-1 induction by LPS in alveolar macrophages and that this regulation occurs through both the NF-κB and the extracellular signal-regulated protein kinase (ERK) signaling pathways. Transient transfections with Fra-1 promoter-reporter constructs and inhibitor studies revealed that the transcriptional activation of Fra-1 by LPS in alveolar macrophages is mediated by NF-κB and ERK1/2 signaling. Importantly, chromatin immunoprecipitation assays revealed the recruitment of c-Jun and NF-κB to the endogenous Fra-1 promoter after LPS stimulation. We found that inhibition of ERK1/2 signaling reduced LPS-stimulated c-Jun and NF-κB recruitment to the promoter. Likewise, NF-κB inhibitor blocked LPS-induced NF-κB and c-Jun binding to the promoter. ERK1/2 inhibition had no effect on c-Jun activation but suppressed LPS-stimulated NF-κB phosphorylation. Finally, functional assays showed reduced levels of LPS-stimulated NF-κB regulated proinflammatory IL-1β and macrophage inflammatory protein-1α expression and increased antiinflammatory IL-10 expression in lung alveolar macrophages of Fra-1-null mice in vivo. Thus, our studies indicate that NF-κB and c-Jun coregulate LPS-induced Fra-1 transcription and that Fra-1 selectively modulates LPS-stimulated inflammatory cytokine expression in lung alveolar macrophages during inflammatory lung injury.

MIP-1α enhances Jurkat cell transendothelial migration by up-regulating endothelial adhesion molecules VCAM-1 and ICAM-1

The aim of this study is to evaluate the expression of macrophage inflammatory protein-1α (MIP-1α) in Jurkat cells and its effect on transendothelial migration. In the present study, human acute lymphoblastic leukemia Jurkat cells (Jurkat cells) were used as a model of T cells in human T-cell acute lymphoblastic leukemia (T-ALL), which demonstrated significantly higher MIP-1α expression compared with that in normal T-cell controls. The ability of Jurkat cells to cross a human brain microvascular endothelial cell (HBMEC) monolayer was almost completely abrogated by MIP-1α siRNA. In addition, the overexpression of MIP-1α resulted in the up-regulated expression of endothelial adhesion molecules, which enhanced the migration of Jurkat cells through a monolayer of HBMEC. MIP-1α levels in Jurkat cells appeared to be an important factor for its transendothelial migration, which may provide the theoretical basis to understand the mechanisms of brain metastases of T-ALL at cellular and molecular levels.

Determination of macrophage inflammatory protein-1α expression in sera from patients with classic Kaposi's sarcoma in Xinjiang Uygur Autonomous Region

Objective To disclose the relationship between the expression of macrophage inflammatory protein-1α (MIP-1α) and the initiation of classic Kaposi's sarcoma.Methods Serum samples were collected from 16 patients with Kaposi's sarcoma,20 patients with herpes zoster,and 20 healthy controls.Enzyme-linked immunosorbent assay was conducted to determine the level of MIP-1α in these samples.Statistitical analysis was done by using the SPSS version 17.0 software.Analysis of variance and rank sum test were carred out to compare the serum level of MIP-1α among these subjects.Results The serum level of MIP-1α was (23.20 ± 0.95) pg/ml in the patients with Kaposi's sarcoma,significantly lower than that in the patients with herpes zoster and healthy controls ((47.21 ± 2.83) pg/ml and (49.14 ± 12.37) pg/ml,respectively,both P ＜ 0.05).No statistical difference was observed between the patients with herpes zoster and healthy controls (P ＞ 0.05).Conclusion The attenuated expression of MIP-1α may be associated with the initiation of Kaposi's sarcoma.

Expression of inflammation-related cytokines following intratracheal instillation of nickel oxide nanoparticles

The objective of this study was to examine what kinds of cytokines are related to lung disorder by well-dispersed nanoparticles. The mass median diameter of nickel oxide in distilled water was 26 nm. Rats intratracheally received 0.2 mg of nickel oxide suspended in distilled water, and were sacrificed from three days to six months. The concentrations of 21 cytokines including inflammation, fibrosis and allergy-related ones were measured in the lung. Infiltration of alveolar macrophages was observed persistently in the nickel oxide-exposed group. Expression of macrophage inflammatory protein-1α showed a continued increase in lung tissue and broncho-alveolar lavage fluid (BALF) while interleukin-1α (IL-1α), IL-1β in lung tissue and monocyte chemotactic protein-1 in BALF showed transient increases. Taken together, it was suggested that nano-agglomerates of nickel oxide nanoparticles have a persistent inflammatory effect, and the transient increase in cytokine expression and persistent increases in CC chemokine were involved in the persistent pulmonary inflammation.

Increased expression of macrophage inflammatory protein-1α on trephine biopsies correlates with extensive bone disease, increased angiogenesis and advanced stage in newly diagnosed patients with multiple myeloma

Increased expression of macrophage inflammatory protein-1α on trephine biopsies correlates with extensive bone disease, increased angiogenesis and advanced stage in newly diagnosed patients with multiple myeloma

Inhibition of p38 Mitogen-Activated Protein Kinase Pathway as Prophylaxis of Postoperative Ileus in Mice

Postoperative ileus, an iatrogenic complication of abdominal surgery, is mediated by severe inflammation of the tunica muscularis. Macrophages that reside in the muscularis have important roles in initiating the inflammation. We investigated whether activation of the p38 mitogen-activated protein kinase (MAPK) and stress-activated protein kinase is involved in the genesis of postoperative ileus, and whether p38-MAPK inhibition by the macrophage-specific inhibitor semapimod prevents intestinal dysmotility. Postoperative ileus was induced by intestinal manipulation of the small bowel in mice. Protein kinase phosphorylation was assessed by immunoblotting of muscularis externa preparations. Proinflammatory gene expression was quantified by real-time polymerase chain reaction. Myeloperoxidase histochemistry for neutrophils was performed in jejunal segments. Nitric oxide production was measured by Griess reaction in smooth-muscle organ culture supernatants. Jejunal contractility was assessed within an organ bath setup. Intestinal motility was analyzed by gastrointestinal and colonic transit measurements. High levels of p38-MAPK and stress-activated protein kinase phosphorylation were observed immediately after intestinal manipulation. Semapimod treatment led to a significant decrease of p38-MAPK phosphorylation in macrophages; proinflammatory gene expression of macrophage inflammatory protein-1alpha, interleukin-6, monocyte chemoattractant protein-1, and intercellular adhesion molecule-1; and neutrophil infiltration. Furthermore, semapimod completely abrogated nitric oxide production within the tunica muscularis. Subsequently, semapimod prevented the suppression of smooth muscle contractility and small intestinal and colonic motility after intestinal manipulation. A single preoperative semapimod administration prevents intestinal macrophage activation and subsequent gastrointestinal dysmotility induced by abdominal surgery. Semapimod inhibits p38-MAPK and nitric oxide production in macrophages, making it a promising strategy for prophylaxis of postoperative ileus.

Ablation of Matrix Metalloproteinase-9 Increases Severity of Viral Myocarditis in Mice

Coxsackievirus B3 (CVB3) causes human myocarditis, which can result in cardiac damage, maladaptive remodeling, and heart failure. Matrix metalloproteinases (MMP)-8 and -9 have been identified in virus-infected myocardium, but their particular roles and underlying mechanisms of effect are unknown. For the first time, we examine the severity of CVB3-induced myocarditis in MMP-8-and MMP-9-deficient mice. CVB3-infected MMP-8 and MMP-9 knockout (KO) mice and corresponding wild-type (WT) mice were euthanized and harvested at 9 days after infection. Expression of MMP-2, -8, -12, and -13 and tissue inhibitors of MMPs was assessed by zymography or immunoblotting on harvested hearts, and in situ hybridization was performed to detect active infection. Infected MMP-9 KO mice had greater myocardial injury and foci of infection than WT mice despite similar pancreatic infection. Increased fibrosis (10.6+/-2.7% versus 7.1+/-2.6%, P=0.04), viral titer, as well as decreased cardiac output, were evident in MMP-9 KO compared with WT mice as assessed by picrosirius red staining, plaque assay, and echocardiography, respectively. Immune infiltration was also greatly increased in MMP-9 KO compared with WT mice (15.2+/-12.6% versus 2.0+/-3.0%, P<0.002). Myocardial interferon-beta1, interferon-gamma, interleukin-6, interleukin-10, and macrophage inflammatory protein-1alpha expression was elevated in MMP-9 KO mice as measured by quantitative real-time polymerase chain reaction and ELISA. In contrast, MMP-8 KO mice had the same degree of cardiac injury, fibrosis, and viral infection as their WT counterparts. During acute CVB3 infection, MMP-9 appears necessary to halt virus propagation in the heart, promote proper immune infiltration and remodeling, and preserve cardiac output.

Nitrogen‐containing bisphosphonate, YM529/ONO‐5920, inhibits macrophage inflammatory protein 1α expression and secretion in mouse myeloma cells

Macrophage inflammatory protein 1 alpha (MIP-1 alpha) is detected at high concentrations in patients with multiple myeloma, and it is thought to play an important role in the etiology of multiple myeloma and osteolysis. Thus, we investigated whether or not YM529/ONO-5920, a new bisphosphonate, inhibited MIP-1 alpha mRNA expression in, and MIP-1 alpha secretion from, mouse myeloma cells. When the cells were stimulated by lipopolysaccharide, increased MIP-1 alpha mRNA expression and MIP-1 alpha secretion were observed. YM529/ONO-5920 inhibited MIP-1 alpha mRNA expression and MIP-1 alpha secretion in a concentration-dependent manner. A transient increase in the phosphorylation of extracellular-regulated kinase 1/2 (ERK1/2) and Akt was observed after lipopolysaccharide stimulation. After YM529/ONO-5920 was given, there was no transient increase in the phosphorylation of ERK1/2 or Akt. These results indicated that YM529/ONO-5920 inhibited the expression and secretion of MIP-1 alpha through blocking the signaling pathway of the Ras/mitogen-activated protein kinase kinase/ERK and Ras/phosphatidylinositol-3 kinase/Akt. Accordingly, YM529/ONO-5920 appears to have promise for use in effective future therapy for osteolysis and myeloma cell growth that depends on MIP-1 alpha.

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

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

Deletion of macrophage-inflammatory protein 1 alpha retards neurodegeneration in Sandhoff disease mice.

Sandhoff disease is a prototypical lysosomal storage disorder in which a heritable deficiency of a lysosomal enzyme, beta-hexosaminidase, results in the storage of the enzyme's substrates in lysosomes. As with many of the other lysosomal storage diseases, neurodegeneration is a prominent feature. Although the cellular and molecular pathways that underlie the neurodegenerative process are not yet fully understood, macrophage/microglial-mediated inflammation has been suggested as one possible mechanism. We now show that the expanded macrophage/microglial population in the CNS of Sandhoff disease mice is compounded by the infiltration of cells from the periphery. Coincident with the cellular infiltration was an increased expression of macrophage-inflammatory protein 1alpha (MIP-1alpha), a leukocyte chemokine, in astrocytes. Deletion of MIP-1alpha expression resulted in a substantial decrease in infiltration and macrophage/microglial-associated pathology together with neuronal apoptosis in Sandhoff disease mice. These mice without MIP-1alpha showed improved neurologic status and a longer lifespan. The results indicate that the pathogenesis of Sandhoff disease involves an increase in MIP-1alpha that induces monocytes to infiltrate the CNS, expand the activated macrophage/microglial population, and trigger apoptosis of neurons, resulting in a rapid neurodegenerative course.

Involvement of p38 mitogen-activated protein kinase followed by chemokine expression in crescentic glomerulonephritis

p38 Mitogen-activated protein kinase (MAPK) is involved in the production and signal transduction of interleukin-1β (IL-1β), tumor necrosis factor-α, and chemokines in vitro. However, the crucial role of p38 MAPK in the inflammatory processes of crescentic glomerulonephritis in vivo remains to be investigated. We showed a dramatic decrease in IL-1β-induced phosphorylation of p38 MAPK, not extracellular signal-regulated kinases 1/2 or jun NH2-terminal kinase, in rat cultured mesangial cells by FR167653. We explored the effects of FR167653 as a specific inhibitor of p38 MAPK on renal injury and subsequent renal expression of chemokines in a progressive experimental crescentic glomerulonephritis model in Wistar-Kyoto rats. Rats developed crescentic glomerulonephritis leading to glomerulosclerosis and interstitial fibrosis by 56 days after the administration of nephrotoxic sera. The number of phosphorylated p38 MAPK-positive cells, detected mainly in crescents, correlated well with the percentage of crescents and number of ED-1-positive cells. Phosphorylated p38 MAPK-positive cells were downregulated in glomeruli in rats with the daily subcutaneous administration of FR167653 for 6 days. Concomitantly, renal expression of macrophage inflammatory protein-1α and monocyte chemoattractant protein-1/monocyte chemotactic and activating factor was markedly reduced by day 6. The severity of glomerulosclerosis and interstitial fibrosis significantly decreased by day 56, and renal function was preserved. These results suggest that p38 MAPK phosphorylation is pivotal for crescentic glomerulonephritis, followed by the subsequent expression of renal chemokines. This study provides evidence that regulation of p38 MAPK is a novel appealing therapeutic target for crescentic glomerulonephritis. © 2001 by the National Kidney Foundation, Inc.

MIP-1α, MCP-1, GM-CSF, and TNF-α Control the Immune Cell Response That Mediates Rapid Phagocytosis of Myelin from the Adult Mouse Spinal Cord

The slow immune response in the adult mammalian CNS results in slow myelin phagocytosis along degenerating white matter after injury. This has important consequences for axon regeneration because of the presence of axon growth inhibitors in myelin. In addition, abnormal immune cell responses in the CNS lead to demyelinating disease. Lysophosphatidylcholine (LPC) can induce an inflammatory response in the CNS, producing rapid demyelination without much damage to adjacent cells. In this study, we searched for the molecular switches that turn on this immune cell response. Using reverse transcription PCR analysis, we show that mRNA expression of macrophage inflammatory protein-1alpha (MIP-1alpha), macrophage chemotactic protein-1 (MCP-1), granulocyte macrophage-colony stimulating factor (GM-CSF), and tumor necrosis factor-alpha (TNF-alpha) in the spinal cord is rapidly and transiently upregulated after intraspinal injection of LPC. Neutralizing these signaling molecules with function-blocking antibodies suppresses recruitment of T-cells, neutrophils, and monocytes into the spinal cord, as well as significantly reduces the number of phagocytic macrophages and the demyelination induced by LPC. These findings will have important implications for CNS regeneration and demyelinating disease.

The effects of feline retroviruses on cytokine expression

To identify potential roles of cytokines in retroviral pathogenesis, we used reverse transcription-quantitative competitive polymerase chain reaction (RT-qcPCR) assays to characterize mRNA levels of 19 different lymphokines, chemokines, monokines and hematopoietic growth factors in three feline cell lines productively infected with subgroup A feline leukemia virus (FeLV-A) or various feline immunodeficiency virus (FIV) strains. Infection of a CD8+, CD5− large granular lymphocyte (LGL) cell line with FeLV-A activated expression of interleukin-7 (IL-7), induced modest (4-fold) increases in granulocyte/macrophage colony-stimulating factor (GM-CSF) and leukemia inhibitory factor (LIF) transcripts, and decreased transforming growth factor-β (TGF-β) mRNA (4-fold). The LGL cells were not susceptible to infection by FIV. Infection of MYA-1 cells, a CD4+ T-lymphoblastoid cell line, with FeLV-A activated expression of macrophage inflammatory protein-1α (MIP-1α), increased transcript levels of GM-CSF (8-fold), macrophage CSF (M-CSF) (16-fold) and stem cell factor (SCF) (250-fold), and decreased (4-fold) expression of IL-10 and tumor necrosis factor-α (TNF-α). Productive infection with four different FIV molecular clones caused progressive MYA-1 cell death; however, the mRNA expression profiles were unchanged except for 2- to 4-fold increases in M-CSF and 16- to 500-fold increases in SCF. Thus, FIV-induced MYA-1 cytopathicity was not associated with dysregulation of pro-apoptotic or survival factor transcript levels. Lastly, productive infection of PNI cells, a marrow-derived fibroendothelial cell line, with FeLV-A or any of three FIV strains induced 4-fold higher levels of IL-12p40 transcripts and variably higher levels (4- to 64-fold) of GM-CSF. Two viral strains, the FIV-14 molecular clone and the clinical isolate FIV-5122, caused syncytia formation and unique activation of IL-1β and stromal cell-derived factor-1 (SDF-1) expression, suggesting a potential role for those factors in viral spread and/or cytopathicity. In addition, infection with FIV-5122, but not the other FIV strains or FeLV-A, induced significant increases in mRNA levels of the hematopoietic inhibitors TNF-α and MIP-1α, along with increased concentrations of soluble proteins in culture supernatants. Consistent with this, supernatant from FIV-5122 infected PNI cells suppressed hematopoietic progenitor growth in colony assays, compared to supportive activities in supernatants from other infected or uninfected PNI cell cultures. Together, these data demonstrate that feline retroviruses alter cytokine mRNA levels in general and strain-specific patterns. These changes may result in specific alterations in cell function and contribute to retroviral pathogenesis. Our observations provide a basis for directed studies of candidate factors within the hematopoietic, thymic and lymphoid microenvironments.

Regulation of Macrophage Inflammatory Protein-1α Expression and Function by Endogenous Interleukin-10 in a Model of Acute Inflammation

In this study we have determined the role of endogenous interleukin (IL)-10 on leucocyte recruitment and production of the CC chemokine macrophage inflammatory protein-1α (MIP-1α) in a murine model of acute inflammation. Intraperitoneal injection of zymosan produced a dose-dependent cellular infiltration which was concomitant with MIP-1α release in the lavage fluids. Release of this chemokine had a functional role since treatment of mice with a specific anti-MIP-1α antibody reduced both neutrophil and monocyte accumulation into the peritoneal cavity. An unexpected increase in cell influx and MIP-1α production was measured following depletion of resident peritoneal macrophages, as achieved by a 3-day liposome treatment. A similar result was obtained when the zymosan peritonitis response was elicited in IL-10 knock-out mice. In summary we propose a functional cross talk between endogenous IL-10 and this CC chemokine during the host inflammatory response.

Regulation of Hyaluronan-Induced Chemokine Gene Expression by IL-10 and IFN-γ in Mouse Macrophages

Abstract Turnover of the extracellular matrix (ECM), activation of macrophages, and accumulation of chemokines/cytokines are all hallmarks of chronic inflammation. Extracellular matrix components, such as hyaluronan (HA), have recently been shown to influence macrophage effector functions, such as the release of inflammatory chemokines and cytokines. Although low m.w. fragments of the glycosaminoglycan HA induce macrophages to secrete numerous inflammatory mediators, the mechanisms regulating ECM-induced macrophage activation are poorly understood. We have examined the effects of IL-10 and IFN-γ on HA-induced chemokine gene expression in primary mouse macrophages. We found that IL-10 and IFN-γ independently inhibit HA-induced expression of macrophage inflammatory protein-1α (MIP-1α), MIP-1β, and KC at both the mRNA and protein levels. Whereas IL-10 inhibited most of the HA-induced chemokines tested, IFN-γ selectively inhibited only MIP-1α, MIP-1β, and KC. This inhibition did not require prestimulation and occurred even when the cytokines were added up to 3 h after stimulation with HA. For MIP-1α, the inhibition by IFN-γ occurred at the level of transcription, whereas IL-10 predominantly decreased the stability of MIP-1α mRNA. IFN-γ and IL-10 equally inhibited macrophage expression of MIP-1β mRNA at the level of transcription, but MIP-1β mRNA stability was decreased to a greater extent by IL-10. These data identify a previously unrecognized role for IL-10 and IFN-γ as regulators of ECM-induced macrophage expression of inflammatory chemokines.

Macrophage Inflammatory Protein-1α Expression in Vivo and in Vitro: The Role of Lipoteichoic Acid

Lipoteichoic acid (LTA), a component of the cell wall of most gram-positive bacteria, has been shown to play a significant role in the initiation and progression of bacterial infection. However, little is known of its position in the cytokine network involved in the induction and perpetuation of inflammation. In this study, we assessed whether the macrophage activating and chemotactic cytokine macrophage inflammatory protein-1α (MIP-1α) was expressed in the setting of localized gram-positive infection. Furthermore, we determined whether LTA purified from either Staphylococcus aureus or Streptococcus pyogenes could induce the expression of MIP-1α mRNA and protein from human blood monocytes. Immunohistochemical staining of human endocardial samples obtained from patients with acute S. aureus endocarditis revealed cell-associated MIP-1α expression by neutrophils, macrophages, and fibroblasts. Treatment of human peripheral blood monocytes in vitro with LTA isolated from either S. aureus or S. pyogenes resulted in both the time- and dose-dependent expression of MIP-1α mRNA. Similarly, staphylococcal and streptococcal LTA induced the dose-dependent production of MIP-1α protein after 24 h in culture. These studies suggest that LTA may play an important role in triggering the recruitment and activation of leukocytes that characterizes the host response to gram-positive bacterial invasion.