Hemozoin-inducible proinflammatory events in vivo: potential role in malaria infection. (57/297)

During malaria infection, high levels of proinflammatory molecules (e.g., cytokines, chemokines) correlate with disease severity. Even if their role as activators of the host immune response has been studied, the direct contribution of hemozoin (HZ), a parasite metabolite, to such a strong induction is not fully understood. Previous in vitro studies demonstrated that both Plasmodium falciparum HZ and synthetic HZ (sHZ), beta-hematin, induce macrophage/monocyte chemokine and proinflammatory cytokine secretion. In the present study, we investigated the proinflammatory properties of sHZ in vivo. To this end, increasing doses of sHZ were injected either i.v. or into an air pouch generated on the dorsum of BALB/c mice over a 24-h period. Our results showed that sHZ is a strong modulator of leukocyte recruitment and more specifically of neutrophil and monocyte populations. In addition, evaluation of chemokine and cytokine mRNA and protein expression revealed that sHZ induces the expression of chemokines, macrophage-inflammatory protein (MIP)-1alpha/CCL3, MIP-1beta/CCL4, MIP-2/CXCL2, and monocyte chemoattractant protein-1/CCL2; chemokine receptors, CCR1, CCR2, CCR5, CXCR2, and CXCR4; cytokines, IL-1beta and IL-6; and myeloid-related proteins, S100A8, S100A9, and S100A8/A9, in the air pouch exudates. Of interest, chemokine and cytokine mRNA up-regulation were also detected in the liver of i.v. sHZ-injected mice. In conclusion, our study demonstrates that sHZ is a potent proinflammatory agent in vivo, which could contribute to the immunopathology related to malaria.  (+info)

High expression of myeloid-related proteins 8 and 14 characterizes an inflammatorily active but ineffective response of macrophages during leprosy. (58/297)

Macrophages are decisive cells for the course of leprosy as they phagocytose Mycobacterium leprae and have the potential to influence the specific immune response. Expression and release of the myeloid-related protein (MRP) 8 and MRP14 (S100A8 and S100A9) characterize a proinflammatory subtype of macrophage that is prominent in, for example, murine infection with lack of a T helper 1 cell response and in certain highly active chronic inflammations of mice and humans. We investigated cutaneous biopsies of the different forms of leprosy (41 untreated patients) including leprosy reaction type 1 (reversal reaction) and type 2 (erythema nodosum leprosum) (n = 18) for expression of MRP8 and MRP14 by subtypes of macrophages. Concomitantly we determined serum levels of MRP8 and MRP14 by sandwich enzyme-linked immunosorbent assay. Expression of MRP8 and MRP14 by CD68-positive macrophages was low in tuberculoid leprosy and rose significantly in borderline tuberculoid leprosy and especially in multibacillary forms, there being expressed by mycobacteria-loaded foam cells. A significant rise of MRP8 and MRP14 expression also occurred in lepra reactions compared to the corresponding non-reactional forms. In type 2 reactions this additional increase was associated with a significant elevation of serum levels. In type 1 it was associated with expression of MRP8 and MRP14 by epitheloid and giant cells, which so far were considered not to express both proteins. In conclusion, we present evidence that the two prominent proteins MRP8 and MRP14 can be re-expressed in vivo by tissue macrophages in chronic infection, that their increased expression is characteristic for a macrophage subtype associated with high inflammatory but low antimycobacterial activity in the absence of a T helper 1 response, and that their significant rise in serum during erythema nodosum leprosum bears diagnostic and pathophysiological relevance.  (+info)

Loss of myeloid-related proteins 8 and myeloid-related proteins 14 expression in human esophageal squamous cell carcinoma correlates with poor differentiation. (59/297)

AIM: To study the expression of myeloid-related proteins(MRP)8 and myeloid-related proteins(MRP)14 in human esophageal squamous cell carcinoma and to investigate if there was any correlation between MRP8 and MRP14 expression level and histopathological grade in these tumors. METHODS: In this study, 65 cases of advanced esophageal squamous cell carcinoma were assessed for MRP8 and MRP14 expression using immunohistochemistry. Statistical analysis was performed for the comparison of MRP8 and MRP14 expression in normal and tumor tissues, and their relationship with clinicopathological features. RESULTS: Reduced or absent expression of MRP8 and MRP14 was observed in esophageal squamous cell carcinoma, with a significant difference between tumor tissues and normal tissues (P<0.01 and P<0.01 for MRP8 and MRP14, respectively). Poorly differentiated tumors presented a greater decrease than well and moderately differentiated tumors, with a correlation between their protein level and histopathological grading (P<0.001 and P<0.001, respectively). However, no significant association was found between MRP8 and MRP14 expression and age or gender (P>0.05). CONCLUSION: These findings suggest that the decreased expression of MRP8 and MRP14 might play an important role in the pathogenesis of human esophageal squamous cell carcinoma, being particularly associated with poor differentiation of tumor cells.  (+info)

Mechanism of apoptosis induced by S100A8/A9 in colon cancer cell lines: the role of ROS and the effect of metal ions. (60/297)

The protein complex S100A8/A9, abundant in the cytosol of neutrophils, is secreted from the cells upon cellular activation and induces apoptosis in tumor cell lines and normal fibroblasts in a zinc-reversible manner. In the present study, we present evidence that the S100A8/A9 also exerts its apoptotic effect by a zinc-independent mechanism. Treatment of the colon carcinoma cells with different concentrations of human S100A8/A9 or the metal ion chelator diethylenetriaminepentacetic acid (DTPA) resulted in a significant increase of cell death. Annexin V/phosphatidylinositol and Hoechst 33258 staining revealed that cell death was mainly of the apoptotic type. A significant increase in the activity of caspase-3 and -9 was observed in both cell lines after treatment. Caspase-8 activation was negligible in both cell lines. The cytotoxicity/apoptotic effect of human S100A8/A9 and DTPA was inhibited significantly (P<0.05) by Zn(+2) and Cu(+2), more effectively than by Ca(2+) and Mg(2+). The antioxidant N-acetyl-L-cysteine inhibited the cytotoxicity/apoptotic effect of S100A8/A9 and DTPA. However, as a result of the different time-courses of both agents and that the S100A8/A9-induced apoptosis was not completely reversed, we conclude that S100A8/A9 exerts its apoptotic effect on two colon carcinoma cell lines through a dual mechanism: one via zinc exclusion from the target cells and the other through a yet-undefined mechanism, probably relaying on the cell-surface receptor(s).  (+info)

Monosodium urate monohydrate crystals induce the release of the proinflammatory protein S100A8/A9 from neutrophils. (61/297)

The neutrophil cytoplasmic protein S100A8/A9 (along with S100A8 and S100A9) is chemotactic and stimulates neutrophil adhesion by activating the beta2-integrin CD11b/CD18. It is also essential to neutrophil migration in vivo in response to monosodium urate monohydrate (MSUM) crystals, the principal etiologic agent of gout. S100A8/A9 is present in the synovial fluid of patients with gout and arthritis and is secreted by activated monocytes; however, its mechanism of release by neutrophils remains unknown. The aim of this study was to identify the mechanism of stimulation of the release of S100A8/A9 by MSUM-activated neutrophils. Here, we show that S100A8/A9 is released by neutrophils stimulated with MSUM crystals and that this release could be enhanced by preincubating neutrophils with granulocyte macrophage-colony stimulating factor. Antibodies directed against CD11b and CD16 blocked the release induced by MSUM crystals, suggesting that Fc receptor for immunoglobulin G (FcgammaR)IIIB (CD16) and CD11b/CD18 were involved in the stimulation by MSUM crystals. Neutrophil preincubation with the Src kinase inhibitor 4-amino-5-(4-chlorophenyl)-7-(t-butyl) pyrazolo[3,4-d]pyrimidine and the Syk tyrosine kinase inhibitor trans-3,3',4,5'-tetrahydrozystilbene significantly reduced the release of S100A8/A9, suggesting that the Src tyrosine kinase family and Syk were involved. In addition, wortmannin reduced neutrophil release of S100A8/A9, indicating a potential involvement of phosphatidylinolitol-3 kinase in this release. Preincubation of neutrophils with the tubulin depolymerization promoters nocodazole and vincristine reduced MSUM-induced release, suggesting a tubulin-associated pathway of release. These results indicate that S100A8/A9 is released by MSUM crystal-stimulated neutrophils following activation of CD11b, CD16, Src kinases, Syk, and tubulin polymerization.  (+info)

A technical triade for proteomic identification and characterization of cancer biomarkers. (62/297)

Biomarkers are needed to elucidate the biological background and to improve the detection of cancer. Therefore, we have analyzed laser-microdissected cryostat sections from head and neck tumors and adjacent mucosa on ProteinChip arrays. Two differentially expressed proteins (P = 3.34 x 10(-5) and 4.6 x 10(-5)) were isolated by two-dimensional gel electrophoresis and identified as S100A8 (calgranulin A) and S100A9 (calgranulin B) by in-gel proteolytic digestion, peptide mapping, tandem mass spectrometry analysis, and immunodepletion assay. The relevance of these single marker proteins was evaluated by immunohistochemistry. Positive tissue areas were reanalyzed on ProteinChip arrays to confirm the identity of these proteins. As a control, a peak with low P was identified as calgizzarin (S100A11) and characterized in the same way. This technical triade of tissue microdissection, ProteinChip technology, and immunohistochemistry opens up the possibility to find, identify, and characterize tumor relevant biomarkers, which will allow the movement toward the clonal heterogeneity of malignant tumors. Taking this approach, proteins were identified that might be responsible for invasion and metastasis.  (+info)

Increased serum levels of MRP-8/14 in type 1 diabetes induce an increased expression of CD11b and an enhanced adhesion of circulating monocytes to fibronectin. (63/297)

The recruitment of monocytes from the bloodstream is crucial in the accumulation of macrophages and dendritic cells in type 1 diabetic pancreases. Adhesion via integrins to endothelium and extracellular matrix proteins, such as fibronectin (FN), and the production of myeloid-related protein (MRP)-8, -14, and -8/14 by recently transmigrated monocytes are thought to be instrumental in such recruitment. We determined the FN-adhesive capacity and integrin expression of monocytes of type 1 and type 2 diabetic patients and related them to the subjects' serum levels of MRP-8, -14 and -8/14. Monocytes of type 1 diabetic patients displayed an increased adhesion to fibronectin in comparison with type 2 patients and healthy control subjects but had a normal expression of the FN binding integrins CD29, CD49a, CD49d, and CD49e (although CD11b and CD18 expression was increased). MRP-8/14, which was increased in the sera of type 1 diabetic patients, induced healthy donor monocytes to adhere to FN and upregulate CD11b expression in a dosage-dependent manner. The observed MRP-induced increased adhesion of monocytes to FN and upregulation of CD11b most likely contributed to a facilitated accumulation of monocytes and monocyte-derived cells at the site of inflammation, in this case the pancreatic islets.  (+info)

Myeloid-related proteins 8 and 14 induce a specific inflammatory response in human microvascular endothelial cells. (64/297)

Myeloid-related protein 8 (MRP8) and MRP14, S100 proteins secreted by activated phagocytes, bind specifically to endothelial cells. The endothelial response to MRP8/MRP14, however, is unknown. Using oligonucleotide microarray analysis, we show for the first time that MRP8/MRP14 induce a thrombogenic, inflammatory response in human microvascular endothelial cells by increasing the transcription of proinflammatory chemokines and adhesion molecules and by decreasing the expression of cell junction proteins and molecules involved in monolayer integrity. All changes on the gene expression level could be confirmed using biochemical and functional assays. We demonstrated that the expression of MRP8/MRP14 closely correlated with the inflammatory activity in systemic vasculitis, confirming the important role of these proteins for distinct inflammatory reactions in endothelia. MRP8/MRP14 may represent novel targets for anti-inflammatory strategies.  (+info)