No abstract

No abstract

To date, diabetes-associated skin ulcerations represent a therapeutic problem of clinical importance. The insulin-resistant type II diabetic phenotype is functionally connected to obesity in rodent models of metabolic syndrome through the release of inflammatory mediators from adipose tissue. Here, we used the impaired wound-healing process in obese/obese (ob/ob) mice to investigate the impact of obesity-mediated systemic inflammation on cutaneous wound-healing processes. Systemic administration of neutralizing monoclonal antibodies against tumor necrosis factor (TNF)alpha (V1q) or monocyte/macrophage-expressed EGF-like module-containing mucin-like hormone receptor-like (Emr)-1 (F4/80) into wounded ob/ob mice at the end of acute wound inflammation initiated a rapid and complete neo-epidermal coverage of impaired wound tissue in the presence of a persisting diabetic phenotype. Wound closure in antibody-treated mice was paralleled by a marked attenuation of wound inflammation. Remarkably, anti-TNFalpha- and anti-F4/80-treated mice exhibited a strong reduction in circulating monocytic cells and reduced numbers of viable macrophages at the wound site. Our data provide strong evidence that anti-TNFalpha therapy, widely used in chronic inflammatory diseases in humans, might also exert effects by targeting "activated" TNFalpha-expressing macrophage subsets, and that inactivation or depletion of misbehaving macrophages from impaired wounds might be a novel therapeutic clue to improve healing of skin ulcers.

The expression of nitric oxide synthase (NOS; EC 1.14.13.39) is induced in rat glomerular mesangial cells by exposure to the inflammatory cytokine interleukin 1 or cAMP-elevating agents. Stimulation with IL-1P alone leadsto an approximately 40-fold increase in NOS activity and nitrite synthesis, whereas the elevation of cAMP with forskolin, cholera toxin, salbutamol, or dibutyryl-cAMP for 24 h resulted in a 2-to 12-fold increase in NOS activity. Moreover, the combinations of IL-1P with each of the cAMP-elevating agents greatly enhanced NOS activity in a synergistic fashion. Northern-blot analysis demonstrated a single band of -4.5 kb for the NOS mRNA in rat mesangial cells. IL-1(3 increased NOS mRNA levels in a dose-and time-dependent fashion with a peak of NOS mRNA at 24 h. Dibutyryl-cAMP also increased NOS mRNA levels in mesangial cells in a dose-and time-dependent manner. Furthermore, combination of IL-11 and forskolin revealed a strong synergy with maximal mRNA levels 12 h after stimulation. Nuclear run-on transcription experiments suggest that IL-1P and cAMP synergistically interact to increase NOS gene expression at the transcriptional level. Furthermore, message stability studies established that NOS mRNA induced by cAMP has a longer half-life than the IL-lu-induced message. Moreover, cAMP exposure markedly prolonged the half-life of NOS mRNA from 1 h to 3 h. These data suggest that the level of NOS mRNA is controlled by at least two different signaling pathways, one involving cAMP and the other being triggered by cytokines such as IL-1p. The two pathways act synergistically and thus potently up-regulate the expression of inducible NOS in rat msangial cells.In recent years, nitric oxide (NO) has been identified as a pleiotropic intercellular messenger molecule regulating a variety of diverse cellular functions in many tissues (1, 2).Initial reports characterized NO as an endothelium-derived relaxing factor important for the maintenance of the vascular tone and the regulation of blood pressure (3, 4). In the brain, NO participates in the actions of excitatory neurotransmitters such as glutamate (1, 5). In macrophages, NO is a cytotoxic mediator and contributes to the antimicrobial and tumoricidal activity of these cells (2, 6). Moreover, NO has been reported to be linked to pathophysiological effects. It may, for instance, account for the destruction of pancreatic islet cells during the development of type I diabetes (7).The generation of NO from L-arginine is catalyzed by NO synthase (NOS; EC 1.14.13.39). Molecular cloning and sequencing analyses revealed the existence of at least three main types of NOS isoforms (1, 2). The earlier report described the molecular cloning of a constitutive brain NOS, a 150 kDa-protein, displaying recognition sites for the three redox cofactors NADPH, FAD, and FMN. The cDNA was cloned from rat cerebellum and identifies a 10-kb mRNA on Northern-blot analysis (8). Recently, the molecular cloning of a distinct constitutive NOS isoform, a 133-kDa protein, from endothel...

IL-18 and IL-18 binding protein (IL-18BP) are two newly described opponents in the cytokine network. Local concentrations of these two players may determine biological functions of IL-18 in the context of inflammation, infection, and cancer. As IL-18 appears to be involved in the pathogenesis of Crohn’s disease and may modulate tumor growth, we investigated the IL-18/IL-18BPa system in the human colon carcinoma/epithelial cell line DLD-1. In this study, we report that IFN-γ induces expression and release of IL-18BPa from DLD-1 cells. mRNA induction and secretion of IL-18BPa immunoreactivity were associated with an activity that significantly impaired release of IFN-γ by IL-12/IL-18-stimulated PBMC. Inducibility of IL-18BPa by IFN-γ was also observed in LoVo, Caco-2, and HCT116 human colon carcinoma cell lines and in the human keratinocyte cell line HaCaT. Induction of IL-18BPa in colon carcinoma/epithelial cell lines was suppressed by coincubation with sodium butyrate. IFN-γ-mediated IL-18BPa and its suppression by sodium butyrate were confirmed in organ cultures of intestinal colonic biopsy specimens. In contrast, sodium butyrate did not modulate expression of IL-18. The present data suggest that IFN-γ may limit biological functions of IL-18 at sites of colonic immune activation by inducing IL-18BPa production. Down-regulation of IL-18BPa by sodium butyrate suggests that reinforcement of local IL-18 activity may contribute to actions of this short-chain fatty acid in the colonic microenvironment.

Interleukin (IL)2 -22 is a newly described member of the IL-10 family of cytokines that is produced by T and NK cells under conditions of immunoactivation. Initiation of the Jak1/Tyk2/ signal transducer and activator of transcription (STAT) 3 pathway appears to be the major mode of IL-22 signal transduction (1-4), although activation of STAT1 (5, 6), mitogen-activated protein kinases (5-7), nuclear factor B (NF-B) (8), activator protein-1 (8), and protein kinase B (6) has been related to this cytokine under specific conditions. IL-22 signaling is established by binding of the cytokine to its heterodimeric receptor complex consisting of IL-22R1 and IL-10R2 (2, 3). Because IL-10R2 is a ubiquitous protein, cellular IL-22 responsiveness is mainly determined by expression of the IL-22R1 receptor chain. Interestingly, IL-22R1 expression is restricted to nonleukocytic cells (9 -11). Therefore, IL-22 appears to be unique among a vast array of cytokines in that this protein is incapable of mediating autocrine or paracrine functions between leukocytes but is rather specialized to transmit information between leukocytes and the nonleukocytic cell compartment. This distinctive biological characteristic essentially discriminates IL-22 from another major activator of the STAT3 signaling system, namely IL-6 (12). Cell types identified to be responsive to IL-22 include synoviocytes (7), pancreatic acinar cells (11), hepatocytes (5, 13, 14), colonic epithelial myofibroblasts (8), and in particular cells of epithelial origin such as keratinocytes (10,15), lung carcinoma cells (16), and colon carcinoma cells (6,17). Proteins that have been reported to be inducible by IL-22 include pro-inflammatory and pro-angiogenic mediators such as IL-8 and enzymes that are involved in cell migration and tissue remodeling such as matrix metalloprotease-1 and -3 (6, 8), effector molecules of innate immunity such as ␤-defensins (10), and immunosuppressive modulators such as IL-10 (17) and SOCS proteins (17, 18). IL-22-induced STAT3 has been associated with induction of the acute phase response (13), with proliferation, and with protection from cell death (6, 14). Interestingly, constitutive activation of the STAT3 pathway is characteristic for numerous human malignancies. Based on the capabilities of this transcription factor to inhibit apoptosis and to promote cell proliferation, STAT3 is actually considered an oncogenic protein (12,19,20).Inducible nitric-oxide synthase (iNOS) and its volatile enzymatic product nitric oxide (NO) have been identified as potential promoters of tumor growth in a variety of human neoplasia, among other colorectal cancers (20 -24). The ability of iNOS to * This work was supported by Deutsche Forschungsgemeinschaft Grants GK1172 Biologicals and SFB 553. The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore be hereby marked "advertisement" in accordance with 18 U.S.C.

No abstract

No abstract