Regulation of interleukin-8 expression in melanoma-stimulated neutrophil inflammatory response

Inflammation facilitates tumor progression including metastasis. Interleukin-8 (IL-8) is a chemokine that regulates polymorphonuclear neutrophil (PMN) mobilization and activity and we hypothesize that this cytokine influences tumor behavior. We have demonstrated that IL-8 is crucial for PMN-mediated melanoma extravasation under flow conditions. In addition, IL-8 is up-regulated in PMNs upon co-culturing with melanoma cells. Melanoma cells induce IkappaB-alpha degradation in PMNs indicating that NF-kappaB signaling is active in PMNs. Furthermore, the production of IL-8 in PMNs is NF-kappaB dependent. We have further identified that interleukin-6 (IL-6) and interleukin-1beta (IL-1beta) from PMN-melanoma co-cultures synergistically contribute to IkappaB-alpha degradation and IL-8 synthesis in PMNs. Taken together, these findings show that melanoma cells induce PMNs to secrete IL-8 through activation of NF-kappaB and suggest a model in which this interaction promotes a microenvironment that is favorable for metastasis.     

Interleukin-1beta induces macrophage inflammatory protein-1beta expression in human hepatocytes

The investigation of factors that regulate expression of CC-chemokines, the important mediators in immune responses and inflammation processes, has an important significance in understanding the immunopathogenesis of liver diseases. We examined the role of interleukin-1beta (IL-1beta), a multifunctional cytokine, in regulating the expression of macrophage inflammatory protein (MIP)-1beta in human hepatocytes (Huh7 and HepG2). IL-1beta significantly enhanced MIP-1beta expression in these cells at both the mRNA and protein levels. Cytokine-enriched supernatants from monocyte-derived macrophage (MDM) cultures also induced MIP-1beta expression. IL-1beta is responsible for MDM supernatant-mediated up-regulation of MIP-1beta since the antibody to IL-1beta abolished MDM supernatant action. Investigation of the mechanism involved in MIP-1beta induction by IL-1beta showed that IL-1beta activated the nuclear factor kappa B (NF-kappaB) promoter in Huh7 cells. In addition, caffeic acid phenethyl ester (CAPE), a specific inhibitor of the activation of NF-kappaB, not only abolished IL-1beta-mediated NF-kappaB promoter activation, but also blocked IL-1beta-induced MIP-1beta expression. These observations suggest that IL-1beta-mediated up-regulation of MIP-1beta production in the hepatic cells may contribute a critical mechanism for continuous recruitment of inflammatory cell to liver and maintenance of inflammation.     

Dysregulation of microRNA-657 influences inflammatory response via targeting interleukin-37 in gestational diabetes mellitus

A number of studies have implicated that microRNAs (miRNAs) play a critical role in the development of gestational diabetes mellitus (GDM). However, the role of miR-657 in GDM remains vague up to date. We aim to investigate the modifying effect of miR-657 on GDM, which will provide new insight into the pathogenesis of GDM and may help to identify new diagnostic or therapeutic targets for GDM. Increased expression of miR-657 but decreased expression of interleukin-37 (IL-37) was observed in patients with GDM. Besides, negative association between miR-657 and IL-37 was demonstrated in this study. miR-657 could targetedly regulate IL-37 and enhance the proliferation of mononuclear macrophages. Moreover, miR-657 promoted the generation of inflammatory cytokines (IL-6 and tumor necrosis factor-α [TNF-α]) and activation of nuclear factor κB (NF-κB) in lipopolysaccharide-induced mononuclear macrophages, while its effect was significantly inhibited when exogenous recombinant IL-37 was administrated into cells. Accordingly, dysregulation of miR-657 contributes to the pathogenesis of GDM via IL-37/NF-κB signaling axis.     

Differential regulation of IGF-II-induced IL-8 by extracellular signal-regulated kinase 1/2 and p38 mitogen-activated protein kinases in human keratinocytes

In order to study the relationship between insulin like growth factor-II (IGF-II) and interleukin-8 (IL-8) that are upregulated in psoriasis, we monitored IL-8 expression in IGF-II-treated human keratinocytes and explored the signaling pathways of IL-8 expression by IGF-II. IGF-II increased the IL-8 mRNA and protein levels in human keratinocytes. The upregulation of IL-8 expression by IGF-II was reduced by pretreatment with inhibitors of tyrosine kinase, Src, PI3-kinase, and ERK, but not by p38. Furthermore, IGF-II remarkably increased the DNA binding activities of NF-kappaB and AP-1, and the IL-8 promoter activity. However, cotransfection with IkappaB mutant blocked the IGF-II-induced IL-8 promoter activity. In addition, cotransfection with dominant negative MEK1 mutant, but not with dominant negative p38 mutant, blocked the IGF-II-induced IL-8 promoter activity. These results suggest that IGF-II is involved in the pathogenesis of psoriasis by inducing IL-8 gene expression through the tyrosine kinase-Src-ERK1/2-AP-1 pathway, and the PI3-kinase and NF-kappaB pathway.     

miR-27a is up regulated and promotes inflammatory response in sepsis

MicroRNAs (miRNAs) are short, non-coding RNAs that regulate the expression of multiple target genes. Dysregulation of miRNAs is common in sepsis. Through microRNA microarray and qRT-PCR we found that the levels of miR-27a, miR-153 and miR-143 are up regulated, while let-7a, miR-218 and miR-129-5p are down regulated in lungs of septic mice. Knocking down of miR-27a down regulates expression levels of TNF-α and IL-6 significantly via reducing the phosphorylation level of NF-κB p65 and inhibiting its DNA binding activity. Furthermore, neutralisation of miR-27a up regulates PPARγ level, down regulates TNF-α expression, relieves pulmonary inflammation and promotes survival of septic mice, which demonstrates that miR-27a plays an important role in regulating inflammatory response in sepsis and provides a potential target for clinical sepsis research and treatment.     

IKKα通过不同机制介导生长促进和生长抑制信号诱导的c-Fos表达和AP-1活化

目的:探讨IKK激酶催化亚基IKKα在分别介导生长促进信号(血清)和生长抑制信号(紫外线UVB)诱导的反应中,调控转录因子AP-1关键组成亚基c-Fos实现诱导表达的信号传递机制。方法:分别采用Western印迹、RT-PCR和萤光素酶报道分析系统检测血清和紫外线刺激反应状态下IKKα对c-Fos诱导表达和AP-1诱导活化的调控作用;通过转染I-κBα功能抑制型突变体I-κBα-AA,观察NF-κB诱导活化受抑时,c-Fos诱导表达和AP-1诱导活化水平的改变情况。结果:IKKα在生长促进和生长抑制信号诱导的反应中,都能够实现对转录因子AP-1及其关键组成亚基c-Fos诱导表达的调控作用。其中,在血清反应中IKKα可通过NF-κB依赖方式在转录水平调控c-Fos的诱导表达,而在UVB反应中IKKα通过转录非依赖方式调控c-Fos的诱导表达。结论:IKKα能分别以NF-κB依赖和非依赖方式参与调控生长促进和生长抑制信号诱导的反应。     

Inhibition of inflammatory response in transgenic fat-1 mice on a calorie-restricted diet

Both n-3 fatty acids (n-3 FA) and calorie-restriction (CR) exert anti-inflammatory effects in animal models of autoimmunity and inflammation. In the present study we investigated the synergistic anti-inflammatory effects of n-3 FA and CR on LPS-mediated inflammatory responses using fat-1 transgenic mice that generate n-3 FA endogenously. Wild-type (WT) and fat-1 mice were maintained on ad libitum (AL) or CR (40% less than AL) diet for 5 mo; splenocytes were cultured in vitro with/without LPS. Our results show: (i) no difference in body weights between WT and fat-1 mice on AL or CR diets, (ii) lower n-6/n-3 FA ratio in splenocytes from fat-1 mice on both AL and CR diets, (iii) significant reduction in NF-kappaB (p65/p50) and AP-1 (c-Fos/c-Jun) DNA-binding activities in splenocytes from fat-1/CR mice following LPS treatment, and (iv) significant reduction in kappaB- and AP-1-responsive IL-6 and TNF-alpha secretion following LPS treatment in splenocytes from fat-1/CR mice. The inhibition of LPS-mediated effects was more pronounced in fat-1/CR mice when compared to fat-1/AL or WT/CR mice. These data show that transgenic expression of fat-1 results in decreased pro-inflammatory n-6 FA, and demonstrate for the first time that splenocytes from fat-1 mice on CR diet exhibit reduced pro-inflammatory response when challenged with LPS. These results suggest that n-3 lipids with moderate CR may confer protection in autoimmune and inflammatory diseases.     

Resveratrol preconditioning modulates inflammatory response in the rat hippocampus following global cerebral ischemia

Considerable evidence has been accumulated to suggests that blocking the inflammatory reaction promotes neuroprotection and shows therapeutic potential for clinical treatment of ischemic brain injury. Consequently, anti-inflammatory therapies are being explored for prevention and treatment of these diseases. Induction of brain tolerance against ischemia by pretreatment with resveratrol has been found to influence expression of different molecules. It remains unclear, however, whether and how resveratrol preconditioning changes expression of inflammatory mediators after subsequent global cerebral ischemia/reperfusion (I/R). Therefore, we investigated the effect of resveratrol pretreatment on NF-κB inflammatory cascade, COX-2, iNOS and JNK levels in experimental I/R. Adult male rats were subjected to 10min of four-vessel occlusion and sacrificed at selected post-ischemic time points. Resveratrol (30mg/kg) pretreatment was injected intraperitoneally 7days prior to I/R induction. We found that resveratrol treatment before insult remarkably reduced astroglial and microglial activation at 7days after I/R. It greatly attenuated I/R-induced NF-κB and JNK activation with decreased COX-2 and iNOS production. In conclusion, the neuroprotection of resveratrol preconditioning may be due in part to the suppression of the inflammatory response via regulation of NF-κB, COX-2 and iNOS induced by I/R. JNK was also suggested to play a protective role through in neuroprotection of resveratrol, which may also be contributing to reduction in neuroinflammation. The study adds to a growing literature that resveratrol can have important anti-inflammatory actions in the brain.     

Protection against UVB-induced damages in human dermal fibroblasts: efficacy of tricin isolated from enzyme-treated Zizania latifolia extract

This study was undertaken to determine the effects of enzyme-treated Zizania latifolia (ETZL) and of its major compound tricin on skin photo-aging and to investigate the mechanisms involved. It was found ETZL and tricin suppressed matrix metalloproteinase (MMP) production and increased type I-procollagen production in UVB-irradiated human dermal fibroblasts (HDFs). Furthermore, ETZL and tricin significantly up-regulated the expressions of the antioxidant enzymes HO-1 and SOD1, reduced UVB-induced reactive oxygen species (ROS) generation and mitogen-activated protein kinase (MAPK) induction by ROS and thereby attenuated activator protein-1 (AP-1) expression. In addition, ETZL and tricin both reduced the phosphorylations of IκBα and IKKα/ß and κB blocked the nuclear translocation of nuclear factor-κB (NF-κB) p65. These results show that ETZL have skin protective effects against UVB and suggest tricin as major efficacious material in ETZL protecting skin photoaging.     

Protection against in vivo liver ischemia-reperfusion injury by n-3 long-chain polyunsaturated fatty acids in the rat

Abstract

N-3 polyunsaturated fatty acids (n-3 PUFA) affect inflammatory processes. This study evaluated the effects of dietary supplementation with fish oil on hepatic ischemia-reperfusion (IR) injury in the rat. Parameters of liver injury (serum transaminases and histology) and oxidative stress (serum 8-isoprostanes and hepatic GSH and GSSG), were correlated with NF-κB DNA binding and FA composition and inflammatory cytokine release. N-3 PUFA supplementation significantly increased liver n-3 PUFA content and decreased n-6/n-3 PUFA ratios. IR significantly modified liver histology and enhanced serum transaminases, 8-isoprotanes and inflammatory cytokines, with net reduction in liver GSH levels and net increment in those of GSSG. Early increase (3 h) and late reduction (20 h) in NF-κB activity was induced. All IR-induced changes were normalized by n-3 PUFA supplementation. In conclusion, prevention of liver IR-injury was achieved by n-3 PUFA supplementation, with suppression of oxidative stress and recovery of pro-inflammatory cytokine homeostasis and NF-κB functionality lost during IR.     

白介素-17在牙龈上皮细胞中调控趋化因子的机制研究

目的：有研究发现白介素-17（IL-17）作为炎症反应的重要标志物在炎症反应中具有重要作用,并且其表达水平的高低与牙周疾病的严重程度有着正相关性,但是目前为止白介素-17对于牙龈上皮细胞的趋化因子生成的影响尚没有研究,所以本课题主要探索在牙龈上皮细胞（human gingival epithelial cells,HGECs）中白介素-17如何通过趋化因子调控炎症反应,并进一步探究其作用机制。方法：酶联免疫吸附剂测定法（enzyme linked immunosorbent assay,ELISA）观察细胞中相关趋化因子分泌,同时蛋白印迹法（western blot）观察细胞中核转录因子κB的变化。结果：无IL-17刺激组与IL-17刺激组比较,IL-17刺激组的趋化因子白介素8（CXCL8）分泌量显著性增加而另一趋化因子单核细胞趋化蛋白-1（CCL2）却没有显著变化,并且通过磷酸化IκB的表达量显著性增加提示NF-κB被激活（P〈0.05）;同时IL-17刺激组与IL-17＋NF-κB抑制剂组比较,IL-17＋NF-κB抑制剂组的CXCL8分泌量显著降低,而通过磷酸化IκB的表达量显著减少提示NF-κB的活性被抑制（P〈0.05）。结论：NF-κB对IL-17刺激下的牙龈上皮细胞趋化因子的表达调控具有关键性作用,同时可能也为将来治疗IL-17诱导的牙周炎症性疾病提供了新的靶点。     

Identification of a nuclear protein that promotes NF-kappaB activation

Receptor-interacting protein (RIP) is a serine/threonine protein kinase that is critically involved in tumor necrosis factor receptor-1 (TNF-R1)-induced NF-kappaB activation. In a yeast two-hybrid screening for potential RIP-interacting proteins, we identified a novel protein designated as NKAP. Although NKAP interacts with RIP in yeast, NKAP does not interact with RIP in mammalian cells in co-immunoprecipitation experiments. When overexpressed in 293 cells, NKAP activated NF-kappaB in a dose-dependent manner. Moreover, down-regulation of NKAP by antisense RNA significantly inhibited TNF- and IL-1-induced NF-kappaB activation. Immunofluorescent staining indicated that NKAP was localized in the nucleus. Our findings suggest that NKAP is a novel nuclear regulator of TNF- and IL-1-induced NF-kappaB activation.     

Cell death by pyruvate deficiency in proliferative cultured calvarial osteoblasts

Cell survival was significantly decreased in primary cultured rat calvarial osteoblasts in vitro at Day 0, 1, and 3 by replacement of the standard culture medium (alpha-modified minimum essential medium; alpha-MEM) with Dulbecco's modified eagle's medium (DMEM). Decreased cell survival was also observed following medium replacement in cultures of murine calvaria-derived osteoblastic cell line MC3T3-E1. Staining with Hoechst33342 revealed apoptotic cells with fragmented or condensed nuclei, while a fraction of the cell culture was stained with propidum iodide, indicating necrosis. Marked increases in DNA binding of both activator protein-1 and nuclear factor-kappaB were found in nuclear extracts of cells following medium replacement. The addition of either pyruvate or cysteine at each concentration found in alpha-MEM almost entirely prevented cell death associated with medium replacement at Day 3. These results suggest that pyruvate and cysteine may be essential factors for cell growth and survival in osteoblast cultures at the proliferative phase.