Vibrio vulnificus AphB is involved in interleukin-8 production via an NF-κB-dependent pathway in human intestinal epithelial cells

We previously reported that the aphB gene mutant of Vibrio vulnificus had significantly impaired motility and adherence to host cells. In this study, we investigated the role of V. vulnificus AphB on the production of interleukin-8 (IL-8), a proinflammatory cytokine, as well as its underlying mechanism in human intestinal epithelial INT-407 cells. The aphB gene mutation significantly reduced the ability of V. vulnificus to stimulate IL-8 production and IL-8 gene promoter activation in INT-407 cells. The V. vulnificusaphB mutant also induced lower levels of NF-κB DNA binding activity and NF-κB minimal promoter activation than did the wild-type of V. vulnificus. Importantly, the observed reductions in IL-8 production, IL-8 gene promoter activation and NF-κB DNA binding activity were significantly restored by complementing the aphB gene into the V. vulnificusaphB mutant. These results indicate that V. vulnificus AphB is involved in the IL-8 production via an NF-κB dependent pathway in human intestinal epithelial cells.     

Pancreatic acinar cells-derived cyclophilin A promotes pancreatic damage by activating NF-κB pathway in experimental pancreatitis

Inflammation triggered by necrotic acinar cells contributes to the pathophysiology of acute pancreatitis (AP), but its precise mechanism remains unclear. Recent studies have shown that Cyclophilin A (CypA) released from necrotic cells is involved in the pathogenesis of several inflammatory diseases. We therefore investigated the role of CypA in experimental AP induced by administration of sodium taurocholate (STC). CypA was markedly upregulated and widely expressed in disrupted acinar cells, infiltrated inflammatory cells, and tubular complexes. In vitro, it was released from damaged acinar cells by cholecystokinin (CCK) induction. rCypA (recombinant CypA) aggravated CCK-induced acinar cell necrosis, promoted nuclear factor (NF)-κB p65 activation, and increased cytokine production. In conclusion, CypA promotes pancreatic damage by upregulating expression of inflammatory cytokines of acinar cells via the NF-κB pathway.     

Chronic intermittent hypoxia induces atherosclerosis by NF-κB-dependent mechanisms

Chronic intermittent hypoxia (CIH) causes atherosclerosis in mice fed a high cholesterol diet (HCD). The mechanisms by which CIH promotes atherosclerosis are incompletely understood. This study defined the mechanistic role of NF-κB pathway in CIH+HCD induced atherosclerosis. Wild type (WT) and mice deficient in the p50 subunit of NF-κB (p50-KO) were fed normal chow diet (ND) or HCD, and exposed to sham or CIH. Atherosclerotic lesions on the en face aortic preparation and cross-sections of aortic root were examined. In WT mice, neither CIH nor HCD exposure alone caused, but CIH+HCD caused evident atherosclerotic lesions on both preparations after 20weeks of exposure. WT mice on ND and exposed to CIH for 35.6weeks did not develop atherosclerotic lesions. P50 gene deletion diminished CIH+HCD induced NF-κB activation and abolished CIH+HCD induced atherosclerosis. P50 gene deletion inhibited vascular wall inflammation, reduced hepatic TNF-α level, attenuated the elevation in serum cholesterol level and diminished macrophage foam cell formation induced by CIH+HCD exposure. These results demonstrate that inhibition of NF-κB activation abrogates the activation of three major atherogenic mechanisms associated with an abolition of CIH+HCD induced atherosclerosis. NF-κB may be a central common pathway through which CIH+HCD exposure activates multiple atherogenic mechanisms, leading to atherosclerosis.     

Bacterial neuraminidase increases IL-8 production in lung epithelial cells via NF-κB-dependent pathway

Bacterial neuraminidase, a sialic acid-degrading enzyme, is one of the virulent factors produced in pathogenic bacteria like as other bacterial components. However little is known about whether bacterial neuraminidase can initiate or modify a cellular response, such as cytokine production, in epithelial cells at infection and inflammation. We demonstrate here that bacterial neuraminidase, but not heat-inactivated neuraminidase, up-regulates expression of interleukin-8 (IL-8) mRNA and protein in lung epithelial A549 and NCI-H292 cells. We also show that bacterial neuraminidase significantly up-regulates IL-8 promoter activity as well as nuclear factor-kappaB (NF-κB) reporter activity. Moreover, inhibition of NF-κB signaling suppressed IL-8 mRNA expression induced by bacterial neuraminidase. Taken together, desialylation-induced IL-8 production in lung epithelial cells may play an important role in infection-associated inflammatory events.     

Helicobacter pylori infection of gastrointestinal epithelial cells in vitro induces mesenchymal stem cell migration through an NF-κB-dependent pathway

The role of bone marrow-derived mesenchymal stem cells (MSC) in the physiology of the gastrointestinal tract epithelium is currently not well established. These cells can be recruited in response to inflammation due to epithelial damage, home, and participate in tissue repair. In addition, in the case of tissue repair failure, these cells could transform and be at the origin of carcinomas. However, the chemoattractant molecules responsible for MSC recruitment and migration in response to epithelial damage, and particularly to Helicobacter pylori infection, remain unknown although the role of some chemokines has been suggested. This work aimed to get insight into the mechanisms of mouse MSC migration during in vitro infection of mouse gastrointestinal epithelial cells by H. pylori. Using a cell culture insert system, we showed that infection of gastrointestinal epithelial cells by different H. pylori strains is able to stimulate the migration of MSC. This mechanism involves the secretion by infected epithelial cells of multiple cytokines, with a major role of TNFα, mainly via a Nuclear Factor-kappa B-dependent pathway. This study provides the first evidence of the role of H. pylori infection in MSC migration and paves the way to a better understanding of the role of bone marrow-derived stem cells in gastric pathophysiology and carcinogenesis.     

Edible blue-green algae reduce the production of pro-inflammatory cytokines by inhibiting NF-κB pathway in macrophages and splenocytes

Background

Chronic inflammation contributes to the development of pathological disorders including insulin resistance and atherosclerosis. Identification of anti-inflammatory natural products can prevent the inflammatory diseases.

Methods

Anti-inflammatory effects of blue-green algae (BGA), i.e., Nostoc commune var. sphaeroides Kützing (NO) and Spirulina platensis (SP), were compared in RAW 264.7 and mouse bone marrow-derived macrophages (BMM) as well as splenocytes from apolipoprotein E knockout (apoE^−/−) mice fed BGA.

Results

When macrophages pretreated with 100 μg/ml NO lipid extract (NOE) or SP lipid extract (SPE) were activated by lipopolysaccharide (LPS), expression and secretion of pro-inflammatory cytokines, such as tumor necrosis factor α (TNFα), interleukin 1β (IL-1β), and IL-6, were significantly repressed. NOE and SPE also significantly repressed the expression of TNFα and IL-1β in BMM. LPS-induced secretion of IL-6 was lower in splenocytes from apoE^−/− fed an atherogenic diet containing 5% NO or SP for 12 weeks. In RAW 264.7 macrophages, NOE and SPE markedly decreased nuclear translocation of NF-κB. The degree of repression of pro-inflammatory gene expression by algal extracts was much stronger than that of SN50, an inhibitor of NF-κB nuclear translocation. Trichostatin A, a pan histone deacetylase inhibitor, increased basal expression of IL-1β and attenuated the repression of the gene expression by SPE. SPE significantly down-regulated mRNA abundance of 11 HDAC isoforms, consequently increasing acetylated histone 3 levels.

Conclusion

NOE and SPE repress pro-inflammatory cytokine expression and secretion in macrophages and splenocytes via inhibition of NF-κB pathway. Histone acetylation state is likely involved in the inhibition.

General significance

This study underscores natural products can exert anti-inflammatory effects by epigenetic modifications such as histone acetylation.     

HOTAIRM1 promotes osteogenic differentiation and alleviates osteoclast differentiation by inactivating the NF-κB pathway

Osteoporosis (OP), one of the most prevalent chronic progressive bone diseases, is caused by deficiency in bone formation by osteoblasts or excessive bone resorption by osteoclasts and subsequently increases the risk of bone fractures. Emerging evidence has indicated that long noncoding RNAs (lncRNAs) play key roles in many biological processes and various disorders. However, the role and mechanism of HOX antisense intergenic RNA myeloid 1 (HOTAIRM1), a myeloid-specific lncRNA, in osteoclast differentiation, osteogenic differentiation, and OP remain unclear. In this study, we found that HOTAIRM1 was upregulated during ossification of ligamentum flavum and osteogenic differentiation, while it was downregulated in osteoclast differentiation and in the bone and serum of human and mouse with OP. Further investigation revealed that silencing Hotairm1 decreased the expression of the osteogenic markers and attenuated osteogenesis. Moreover, forced Hotairm1 expression inhibited the expressions of the osteoclastogenesis markers and alleviated receptor activator of nuclear factor kappa B (NF-κB) ligand (RANKL)-induced osteoclast differentiation. Mechanically, Hotairm1 repressed the phosphorylation of p65 and inhibitor of κBα (IκBα) and attenuated RANKL-mediated enhancement of phos-p65 and IκBα, suggesting that Hotairm1 inhibits RANKL-induced osteoclastogenesis through the NF-κB pathway. In conclusion, our data identified a crucial role of HOTAIRM1 in OP, providing a proof of this molecule as a potential diagnostic marker and a possible therapeutic target against OP.     

Tumour necrosis factor-α suppresses the hypoxic response by NF-κB-dependent induction of inhibitory PAS domain protein in PC12 cells

Inflammation is often accompanied by hypoxia. However, crosstalk between signalling pathways activated by inflammation and signalling events that control adaptive response to hypoxia is not fully understood. Here we show that exposure to tumour necrosis factor-α (TNF-α) activates expression of the inhibitory PAS domain protein (IPAS) to suppress the hypoxic response caused by hypoxia-inducible factor (HIF)-1 and HIF-2 in rat pheochromocytoma PC12 cells but not in human hepatoma Hep3B cells. This induction of IPAS was dependent on the nuclear factor-κB (NF-κB) pathway and attenuated hypoxic induction of HIF-1 target genes such as tyrosine hydroxylase (TH) and vascular endothelial growth factor (VEGF). HIF-dependent reporter activity in hypoxia was also decreased following TNF-α treatment. Knockdown of IPAS mRNA by small interfering RNA (siRNA) restored the TNF-α-suppressed hypoxic response. These results indicate that TNF-α is a cell-type specific suppressor of HIFs and suggest a novel crosstalk between stimulation by inflammatory mediators and HIF-dependent hypoxic response.     

Upregulation of CD271 transcriptome in breast cancer promotes cell survival via NFκB pathway

Molecular Biology Reports - Biological treatment of many cancers currently targets membrane bound receptors located on a cell surface. We are in a great to need identify novel membrane proteins...     

BRCA-1 depletion impairs pro-inflammatory polarization and activation of RAW 264.7 macrophages in a NF-κB-dependent mechanism

Molecular and Cellular Biochemistry - Inadequate migration and invasion of the trophoblast cells during embryo implantation is one of the reasons for pregnancy-related complications such as...     

Porphyromonas gingivalis promotes the motility of esophageal squamous cell carcinoma by activating NF-κB signaling pathway

Esophageal carcinoma, with a increasing incidence, is one of the most aggressive carcinomas in gastrointestinal tract. Epidemiologic studies demonstrate an association of oral pathogens with multiple diseases, including rheumatoid arthritis, cardiovascular diseases, diabetes, and gastrointestinal malignancies. Nevertheless, a causal relationship between oral pathogens and esophageal squamous cell carcinoma (ESCC) has not been elucidated. Here, we found that Porphyromonas was significantly enriched in the saliva of patients with ESCC, compared with that in normal human. In vitro studies showed that Porphyromonas gingivalis (P. gingivalis) promoted the proliferation and motility of ESCC cells, as evidenced by up regulated expression of key molecules implicated in NF-κB signaling pathway. These findings, for the first time, demonstrated a role of oral pathogens in inducing ESCC tumorigenesis and metastasis, which might involve regulation of NF-κB signaling pathway.     

TRAF2 phosphorylation promotes NF-κB-dependent gene expression and inhibits oxidative stress-induced cell death

Tumor necrosis factor α (TNF-α) receptor-associated factor 2 (TRAF2) regulates activation of the c-Jun N-terminal kinase (JNK)/c-Jun and the inhibitor of κB kinase (IKK)/nuclear factor κB (NF-κB) signaling cascades in response to TNF-α stimulation. Gene knockout studies have revealed that TRAF2 inhibits TNF-α-induced cell death but promotes oxidative stress-induced apoptosis. Here we report that TNF-α and oxidative stress both induce TRAF2 phosphorylation at serines 11 and 55 and that this dual phosphorylation promotes the prolonged phase of IKK activation while inhibiting the prolonged phase of JNK activation. Prolonged IKK activation trigged by TNF-α plays an essential role in efficient expression of a subset of NF-κB target genes but has no substantial role in TNF-α-induced cell death. On the other hand, TRAF2 phosphorylation in response to oxidative stress significantly promotes cell survival by inducing prolonged IKK activation and by inhibiting the prolonged phase of JNK activation. Notably, stable expression of phospho-null mutant TRAF2 in cancer cells leads to an increase in the basal and inducible JNK activation and B-cell lymphoma 2 (Bcl-2) phosphorylation. In addition, exposure of cells expressing phospho-null mutant TRAF2 to sublethal oxidative stress results in a rapid degradation of Bcl-2 and cellular inhibitor of apoptosis 1 as well as significantly increased cell death. These results suggest that TRAF2 phosphorylation is essential for cell survival under conditions of oxidative stress.     

Protein kinase C and NF-κB-dependent CD4 downregulation in macrophages induced by T cell-derived soluble factors: consequences for HIV-1 infection

Upon activation, CD4(+) T cells release cytokines, chemokines, and other soluble factors that influence the kinetics of HIV-1 replication in macrophages (M). In this article, we show that activation of human primary T cells suppresses the early stages of HIV-1 replication in human primary Mφ by downregulating the main cellular receptor for the virus CD4. The secreted factors responsible for this effect have a molecular mass greater than conventional cytokines, are independent of Th1 or Th2 polarization, and are not IFN-γ, IL-16, RANTES, or macrophage inhibitory factor, as revealed by cytokine array analysis and neutralization assays. CD4 downregulation is entirely posttranslational and involves serine phosphorylation of CD4 and its targeting to an intracellular compartment destined for acidification and degradation. CD4 downregulation is dependent on the activities of both protein kinase C and NF-κB as well as the proteasomes. Using high-resolution liquid chromatography-tandem mass spectrometry analysis in conjugation with label-free protein quantitation software, we found that proteins that promote Mφ adherence and spreading, such as attractin, fibronectin, and galectin-3-binding protein, were significantly overrepresented in the activated T cell supernatant fractions. These results reveal the existence of previously unreported anti-HIV-1 proteins, released by activated T cells that downregulate CD4 expression, and are of fundamental importance to understand the kinetics of HIV infection in vivo.     

S100A7 promotes the development of human endometriosis by activating NF-κB signaling pathway in endometrial stromal cells

Endometriosis (EM) is a chronic inflammatory disease affecting women aged between 23 and 42 years with a prevalence of 6%–10%. S100A7, a member of the S100 protein family, has been implicated in promoting inflammation. However, the role of S100A7 in EM and its underlying mechanism remain to be elucidated. S100A7 was silenced or overexpressed in primary endometrial stromal cells (ESCs). Cell proliferation was determined using a Cell Counting Kit-8. Cell cycle/apoptosis was monitored using a flow cytometer. Cell invasion was studied by a Transwell assay. Quantitative RT-PCR and Western blot analyses were used to evaluate gene expression. S100A7 and NF-κB expression is increased in both endometriotic tissue and ESCs from women with EM. The expression of S100A7 is correlated with the expression of NF-κB. S100A7 knockdown inhibits ESCs proliferation, cell cycle progression, cell invasion, and inflammation, but promotes cell apoptosis in an NF-κB dependent manner. In contrast, S100A7 overexpression demonstrated an inverse effect. S100A7 is increased in both endometriotic tissue and ESCs from women with EM. S100A7 overexpression contributes to EM through increasing ESCs proliferation, cell cycle progression, cell invasion, and inflammation, and inhibiting cell apoptosis in the NF-κB dependent manner. These findings highlight the importance of S100A7/NF-κB signaling in EM and provide new insights into therapeutic strategies for EM.