Macrophages produce an array of proinflammatory mediators at sites of inflammation and contribute to the development of inflammatory responses. Important roles for cytokines, such as IL-1 or TNF-α, and bacterial products, such as LPS, in this process have been well documented; however, the role for the extracellular matrix proteins, such as collagen, remains unclear. We previously reported that discoidin domain receptor 1 (DDR1), a nonintegrin collagen receptor, is expressed during differentiation of human monocytes into macrophages, and the interaction of the DDR1b isoform with collagen facilitates their differentiation via the p38 mitogen-activated protein kinase (MAPK) pathway. In this study, we report that the interaction of DDR1b with collagen up-regulates the production of IL-8, macrophage inflammatory protein-1α, and monocyte chemoattractant protein-1 in human macrophages in a p38 MAPK- and NF-κB-dependent manner. p38 MAPK was critical for DDR1b-mediated, increased NF-κB trans-activity, but not for IκB degradation or NF-κB nuclear translocation, suggesting a role for p38 MAPK in the modification of NF-κB. DDR1b-mediated IκB degradation was mediated through the recruitment of the adaptor protein Shc to the LXNPXY motif of the receptor and the downstream TNFR-associated factor 6/NF-κB activator 1 signaling cascade. Taken together, our study has identified NF-κB as a novel target of DDR1b signaling and provided a novel mechanism by which tissue-infiltrating macrophages produce large amounts of chemokines during the development of inflammatory diseases. Intervention of DDR1b signaling may be useful to control inflammatory diseases in which these proteins play an important role.

Pulmonary tuberculosis, one of the granulomatous diseases, has few serological markers for its activity. Recently, an increased serum level of vascular endothelial growth factor (VEGF) was detected in patients with Crohn's disease, also a granulomatous disease. We hypothesized that VEGF might be associated with the pathogenesis of pulmonary tuberculosis. We investigated the serum level of VEGF in 43 patients with active pulmonary tuberculosis, 29 patients with old tuberculosis, and 25 patients with acute bronchitis. We were able to examine the serum VEGF levels every 3 mo for a period of 6 mo in seven patients with active pulmonary tuberculosis. We examined the presence of VEGF in the resected lungs of three patients with active pulmonary tuberculosis by immunohistochemistry. The serum levels of VEGF were significantly higher in patients with active pulmonary tuberculosis than in patients with old tuberculosis and acute bronchitis. The decrease in titer of serum VEGF paralleled the clinical improvement of patients with pulmonary tuberculosis. Immunohistochemical staining of the resected lungs demonstrated the presence of VEGF in alveolar macrophages surrounding the lesion. Therefore, VEGF may be associated with the pathogenesis of pulmonary tuberculosis.

SUMMARYTumour necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL) is a member of the TNF superfamily, which is capable of inducing apoptosis in many cell types, including tumour and virus-infected cells, but rarely in normal cells. Expression of TRAIL mRNA and TRAIL receptors has previously been detected in neutrophils; however, the expression of TRAIL protein and the regulation of TRAIL and TRAIL receptor expression in these cells remain unknown. Here we report, for the ®rst time, that neutrophils constitutively express TRAIL protein on their cell surface and that the TRAIL protein is shed during culture. TNF-a is a down-regulator of TRAIL expression, whereas IFN-g up-regulates the expression of TRAIL. Neutrophils did not express a detectable level of TRAIL-R1 or -R4, but constitutively expressed a low, but substantial, level of TRAIL-R2 and a high level of TRAIL-R3. Although the level of TRAIL-R2 was not signi®cantly altered during culture under different experimental conditions, %30% of TNF-a-treated cells rapidly lost their high-level TRAIL-R3 expression, whereas the majority of IFN-g-treated cells retained a high level of TRAIL-R3 expression. Anti-TRAIL neutralizing antibody signi®cantly inhibited neutrophil apoptosis during cultures in medium alone, or in the presence of TNF-a or IFN-g. Thus, our study identi®ed human neutrophils as a cellular source of TRAIL and suggests that neutrophilderived TRAIL may play a role in immune surveillance. Our results also suggest a role for the TRAIL/TRAIL receptor system in neutrophil apoptosis.

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Discoidin domain receptor 1 (DDR1) is a receptor tyrosine kinase activated by collagen. DDR1 is constitutively expressed in a variety of normal and transformed epithelial cells and plays a role in cell migration and differentiation through as yet unidentified signaling pathways. We previously reported inducible expression of DDR1 in human leukocytes and suggested a role for the DDR1a isoform in leukocyte migration through extracellular matrix. Here, we evaluated the contribution of DDR1 in the differentiation of the human monocytic THP-1 cells overexpressing these isoforms and of primary macrophages. Interestingly, collagen activation of DDR1b, but not DDR1a, further promoted phorbol ester-induced differentiation of THP-1 cells as determined by reduced cell proliferation and up-regulated expression of HLA-DR, CD11c, CD14, and CD40. Collagen activation of DDR1b also induced the recruitment and phosphorylation of Shc and subsequent phosphorylation of p38 mitogen-activated protein (MAP) kinase and its substrate ATF2. A p38 MAP kinase inhibitor, SB203580, completely inhibited DDR1b-mediated HLA-DR expression. Activation of DDR1 endogenously expressed on macrophages also up-regulated their HLA-DR expression in a p38 MAP kinase-dependent manner. Thus, DDR1b in response to collagen transduces signals that promote maturation/differentiation of HLA-DR-positive antigen-presenting cells and contributes to the development of adaptive immunity in a tissue microenvironment.

No abstract

Malignant pleural effusion (PE) is one of the poor prognostic factors in non-small cell lung cancer (NSCLC), and the detailed mechanism of the malignant PE formation is not fully elucidated. Recently, CXCR4, a receptor for chemokine stromal-derived factor-1alpha (SDF-1alpha) that can induce chemotaxis of cells, was reported to be expressed on NSCLC. In this study, we hypothesized that the SDF-1alpha/CXCR4 axis may be involved in the dissemination of malignant cells into pleural space, and investigated its expression, function, and signaling pathway using NSCLC cell lines and clinical samples from 43 patients with NSCLC with malignant PE. We found functional expression of CXCR4 on NSCLC cell lines, and also found that SDF-1alpha could induce migration via phosphatidylinositol 3 (PI-3) kinase- and p44/42 mitogen-activated protein kinase-dependent manner. The SDF-1alpha levels in malignant PE were significantly higher than those in transudate PE and showed a significant positive correlation with PE volumes. The sensitivity and specificity for prediction of recurrence of malignant PE was 61.5% and 83.3%, respectively (cutoff SDF-1alpha = 2,500 ng/ml), and better than those using pH of PE. Cancer cells in malignant PE expressed CXCR4, and mesothelial cells of the pleura stained positive for SDF-1alpha. The SDF-1alpha/CXCR4 axis is involved in the dissemination of NSCLC cells into pleural space.

Neutropenia is a common laboratory finding in systemic lupus erythematosus (SLE). However, the molecular mechanism of SLE neutropenia has not been fully explained. In this study, we examined whether TNF-related apoptosisinducing ligand (TRAIL) is involved in the pathogenesis of SLE neutropenia using samples from SLE patients. Serum TRAIL levels in SLE patients with neutropenia were significantly higher than those of SLE patients without neutropenia and healthy volunteers. Serum TRAIL levels showed a significant negative correlation with neutrophil counts in SLE patients. The expression of TRAIL receptor 3 was significantly lower in SLE patients with neutropenia than in patients without neutropenia or in healthy volunteers. Treatment with glucocorticoids negated the decrease of TRAIL receptor 3 expression on neutrophils of SLE patients. TRAIL may accelerate neutrophil apoptosis of neutrophils from SLE patients, and autologous T cells of SLE patients, which express TRAIL on surface, may kill autologous neutrophils. IntroductionNeutropenia in systemic lupus erythematosus (SLE) was first described more than 70 years ago 1 and is found in about 50%-60% of patients with SLE. 2 Clinically, increased susceptibility to infections is a major cause of morbidity and mortality in patients with SLE. 3,4 In this regard, not only treatment with adrenal glucocorticoids and/or immunosuppressive drugs but also decreased numbers of polymorphonuclear neutrophils (PMNs) is obviously responsible for the increased incidence of infections. [5][6][7][8][9] However, the detailed molecular mechanism of neutropenia in SLE has not been fully elucidated.Traditionally, PMNs have been considered to be the first line cell component of the body defense mechanism against bacterial pathogens and were regarded as terminally differentiated cells incapable of protein synthesis and committed to death within 72 hours. [10][11][12] Recently, it was indicated that neutrophils were not only capable of receiving signals from different proinflammatory cytokines and chemokines, but also could synthesize many important proinflammatory cytokines and chemokines to modulate immune responses, such as interferon-gamma (IFN-␥), tumor necrosis factor alpha (TNF-␣), and interleukin-8 (IL-8). 13,14 And these proinflammatory mediators, relevant to the inflamed site in vivo, also act to modulate the constitutive death of neutrophils. 15,16 Regarding neutrophil apoptosis, Fas 17 and TNF-␣ 18 were reported to be able to shorten neutrophil lifespan at early time points. Recently, it was reported that TNF-related apoptosis-inducing ligand (TRAIL) could accelerate neutrophil apoptosis. 19 Also, TRAIL was reported to be involved in the monocyte apoptosis induced by T cells in SLE. 20 However, the role of TRAIL in neutropenia of SLE is still unclear.In this study, we have investigated the TRAIL receptors on neutrophils and TRAIL-induced neutrophil apoptosis using samples from SLE patients. A difference in the expression pattern of TRAIL receptors between SLE patients and healt...