Human mesenchymal stromal cells modulate T‐cell responses through TNF‐α‐mediated activation of NF‐κB

Although mesenchymal stromal cells (MSCs) possess the capacity to modulate immune responses, little is known about the mechanisms that underpin these processes. In this study, we show that immunosupression is mediated by activation of nuclear factor kappa B (NF‐κB) in human MSCs. This pathway is activated by TNF‐α that is generated following TCR stimulation of T cells. Inhibition of NF‐κB through silencing of IκB kinase β or the TNF‐α receptor abolishes the immunosuppressive capacity of MSCs. Our data also indicate that MSC‐associated NF‐κB activation primarily leads to inhibition of T‐cell proliferation with little effect on expression of the activation markers CD69 and CD25. Thus, our data support the hypothesis that the TNF‐α/NF‐κB signalling pathway is required for the initial priming of immunosuppressive function in human MSCs. Interestingly, drugs that interfere with NF‐κB activation significantly antagonise the immunoregulatory effect of MSCs, which could have important implications for immunosuppression regimens in the clinic.     

Expression of classical NF‐κB pathway effectors in human ovarian carcinoma

Darb‐Esfahani S, Sinn B V, Weichert W, Budczies J, Lehmann A, Noske A, Buckendahl A‐C, Müller B M, Sehouli J, Koensgen D, Györffy B, Dietel M & Denkert C
(2010) Histopathology 56. 727–739
Expression of classical NF‐κB pathway effectors in human ovarian carcinoma Aims: Functional studies have demonstrated that nuclear factor (NF)‐κB promotes tumour progression in ovarian cancer cells. However, surprisingly little is known of the expression of effectors of the NF‐κB pathway in human ovarian cancer in vivo. Methods and results: Immunohistochemistry and in situ hybridization revealed that in a cohort of 85 primary ovarian carcinomas, total p65 expression was inversely correlated to nuclear and cytoplasmic phospho‐IκBα (P = 0.002 and P = 0.05, respectively), and IκBα mRNA expression (P = 0.032). In contrast, phospho‐p65 expression was paralleled by the expression of nuclear (P = 0.027) and cytoplasmic phospho‐IκBα (P = 0.01). Total p65 expression was an adverse prognostic factor for overall survival (P = 0.018). In contrast, total IκBα and phosphorylated nuclear and cytoplasmic IκBα expression were favourable prognostic markers (P = 0.001, P = 0.031, P = 0.001, respectively). Cytoplasmic phospho‐IκBα expression remained a significant prognostic factor on multivariate analysis (P = 0.010). In cultured, stimulated OVCAR‐3 ovarian cancer cells the cytoplasmic retranslocation of p65 was delayed by inhibition of the nuclear membrane transporter chromosomal region maintenance/exportin1 protein (CRM1). A positive association of p65 and CRM1 expression was demonstrated in ovarian cancer tissue (P < 0.0001). Conclusions: Total and phosphorylated IκBα protein expression might serve as markers for NF‐κB activation in human ovarian carcinoma. Cytoplasmic localization of p65 may be related to deregulated nucleocytoplasmic transport in carcinomas overexpressing CRM1.     

Recombinant pyrin domain protein attenuates allergic inflammation by suppressing NF‐κB pathway in asthmatic mice

Pyrin domain (PYD), a subclass of protein motif known as the death fold, is frequently involved in inflammation and immune responses. PYD modulates nuclear factor‐kappa B (NF‐κB) signalling pathway upon various stimuli. Herein, a novel recombinant pyrin domain protein (RPYD) was generated. Its role and mechanism in inflammatory response in an ovalbumin (OVA) induced asthma model was investigated. After OVA challenge, there was inflammatory cell infiltration in the lung, as well as airway hyper‐responsiveness (AHR) to inhaled methacholine. In addition, eosinophils increased in the bronchoalveolar lavage fluids, alone with the elevated levels of Th‐2 type cytokines [interleukin (IL)‐4, IL‐5 and IL‐13], eotaxin, and adhesion molecules. However, the transnasal administration of RPYD before the OVA challenge significantly inhibited these asthmatic reactions. Moreover, RPYD markedly suppressed NF‐κB translocation, reduced phosphorylation of p38 MAPK, and thus attenuated the expression of intercellular adhesion molecule 1 and IL‐6 in the BEAS‐2B cells stimulated by proinflammatory cytokines in vitro. These findings indicate that RPYD can protect asthma host from OVA‐induced airway inflammation and AHR via down‐regulation of NF‐κB and p38 MAPK activities. RPYD may be used as a potential medicine for the treatment of asthma in clinic.     

NF‐κB1, NF‐κB2 and c‐Rel differentially regulate susceptibility to colitis‐associated adenoma development in C57BL/6 mice

NF‐κB signalling is an important factor in the development of inflammation‐associated cancers. Mouse models of Helicobacter‐induced gastric cancer and colitis‐associated colorectal cancer have demonstrated that classical NF‐κB signalling is an important regulator of these processes. In the stomach, it has also been demonstrated that signalling involving specific NF‐κB proteins, including NF‐κB1/p50, NF‐κB2/p52, and c‐Rel, differentially regulate the development of gastric pre‐neoplasia. To investigate the effect of NF‐κB subunit loss on colitis‐associated carcinogenesis, we administered azoxymethane followed by pulsed dextran sodium sulphate to C57BL/6, Nfkb1^?/?, Nfkb2^?/?, and c‐Rel^?/?mice. Animals lacking the c‐Rel subunit were more susceptible to colitis‐associated cancer than wild‐type mice, developing 3.5 times more colonic polyps per animal than wild‐type mice. Nfkb2^?/? mice were resistant to colitis‐associated cancer, developing fewer polyps per colon than wild‐type mice (median 1 compared to 4). To investigate the mechanisms underlying these trends, azoxymethane and dextran sodium sulphate were administered separately to mice of each genotype. Nfkb2^?/? mice developed fewer clinical signs of colitis and exhibited less severe colitis and an attenuated cytokine response compared with all other groups following DSS administration. Azoxymethane administration did not fully suppress colonic epithelial mitosis in c‐Rel^?/? mice and less colonic epithelial apoptosis was also observed in this genotype compared to wild‐type counterparts. These observations demonstrate different functions of specific NF‐κB subunits in this model of colitis‐associated carcinogenesis. NF‐κB2/p52 is necessary for the development of colitis, whilst c‐Rel‐mediated signalling regulates colonic epithelial cell turnover following DNA damage. © 2015 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of Pathological Society of Great Britain and Ireland.     

Optineurin deficiency in mice is associated with increased sensitivity to Salmonella but does not affect proinflammatory NF‐κB signaling

Optineurin (OPTN) is an evolutionary conserved and ubiquitously expressed ubiquitin‐binding protein that has been implicated in glaucoma, Paget bone disease, amyotrophic lateral sclerosis, and other neurodegenerative diseases. From in vitro studies, OPTN was shown to suppress TNF‐induced NF‐κB signaling and virus‐induced IRF signaling, and was identified as an autophagy receptor required for the clearance of cytosolic Salmonella upon infection. To assess the in vivo functions of OPTN in inflammation and infection, we generated OPTN‐deficient mice. OPTN knockout mice are born with normal Mendelian distribution and develop normally without any signs of spontaneous organ abnormality or inflammation. However, no differences in NF‐κB activation could be observed in OPTN knockout mice or fibroblasts derived from these mice upon TNF or LPS treatment. Primary bone marrow‐derived macrophages from OPTN‐deficient mice had slightly impaired IRF signaling and reduced IFN type I production in response to LPS or poly(I,C). Finally, OPTN‐deficient mice were more susceptible to infection with Salmonella, confirming in vivo the importance of OPTN in bacterial clearance.     

5,7‐dihydroxy‐3,4,6‐trimethoxyflavone inhibits the inflammatory effects induced by Bacteroides fragilis enterotoxin via dissociating the complex of heat shock protein 90 and IκBα and IκB kinase‐γ in intestinal epithelial cell culture

Enterotoxin produced by enterotoxigenic Bacteroides fragilis (BFT) has been associated with mucosal inflammation and diarrhoeal diseases. In this study, the anti‐inflammatory molecular mechanism of 5,7‐dihydroxy‐3,4,6‐trimethoxyflavone (eupatilin) was characterized in an HT‐29 intestinal epithelial cell line stimulated with BFT. Pre‐treatment of HT‐29 cells with eupatilin decreased the production significantly of both interleukin (IL)‐8 and prostaglandin E₂ induced by BFT in a dose‐dependent manner. BFT‐activated nuclear factor‐kappaB (NF‐κB) signals in HT‐29 cells and pretreatment with eupatilin suppressed NF‐κB activation that resulted in the significant inhibition of IL‐8 and cyclo‐oxygenase‐2 expression. BFT‐induced phosphorylation of both IκBα and IκB kinase (IKK) signals was prevented in eupatilin‐pretreated HT‐29 cells. Transfection of siRNA for IKK‐α and IKK‐β decreased the production of IL‐8 and prostaglandin E₂; however, the transfection of IKK‐β siRNA showed a more significant reduction of BFT‐induced IκBα phosphorylation compared with that of IKK‐α siRNA. In addition, herbimycin A, a specific inhibitor of heat shock protein 90 (Hsp90), decreased the BFT‐induced activation of IKK and NF‐κB, suggesting that Hsp90 is associated with a pathway of IKK‐NF‐κB‐IL‐8/cyclo‐oxygenase‐2 gene signalling. Furthermore, eupatilin dissociated the complex between Hsp90 and IKK‐γ in BFT‐stimulated HT‐29 cells. These results suggest that eupatilin can suppress the NF‐κB signalling pathway by targeting the Hsp90‐IKK‐γ complex in intestinal epithelial cells and may attenuate BFT‐induced inflammatory responses.     

NF‐κB‐inducing kinase is essential for B‐cell maintenance in mice

NF‐κB‐inducing kinase (NIK) is a key mediator of the noncanonical NF‐κB signaling pathway, which is critical for normal B‐cell development and function. It is well established that the complete deletion of NIK in mice results in defective B cells and impaired secondary lymphoid organogenesis. To address the role of NIK deficiency specifically in B cells, we generated a new mouse strain for the conditional deletion of this kinase. Deletion of NIK during B‐cell development results in a drastic reduction of mature B cells from the transitional 2 stage on, while B‐1 B cells are less affected. Moreover, deletion of NIK in the germinal centers decreases the numbers of germinal center B cells and impairs the ability of NIK‐deficient B cells to develop into class‐switched cells in vivo. This new mouse strain will be helpful for studying the role of NIK in different cell types of the body.     

Vitamin K3 attenuates lipopolysaccharide‐induced acute lung injury through inhibition of nuclear factor‐κB activation

Vitamin K is a family of fat‐soluble compounds including phylloquinone (vitamin K₁), menaquinone (vitamin K₂) and menadione (vitamin K₃). Recently, it was reported that vitamin K, especially vitamins K₁ and K₂, exerts a variety of biological effects, and these compounds are expected to be candidates for therapeutic agents against various diseases. In this study, we investigated the anti‐inflammatory effects of vitamin K₃ in in vitro cultured cell experiments and in vivo animal experiments. In human embryonic kidney (HEK)293 cells, vitamin K₃ inhibited the tumour necrosis factor (TNF)‐α‐evoked translocation of nuclear factor (NF)‐κB into the nucleus, although vitamins K₁ and K₂ did not. Vitamin K₃ also suppressed the lipopolysaccharide (LPS)‐induced nuclear translocation of NF‐κB and production of TNF‐α in mouse macrophage RAW264·7 cells. Moreover, the addition of vitamin K₃ before and after LPS administration attenuated the severity of lung injury in an animal model of acute lung injury/acute respiratory distress syndrome (ARDS), which occurs in the setting of acute severe illness complicated by systemic inflammation. In the ARDS model, vitamin K₃ also suppressed the LPS‐induced increase in the serum TNF‐α level and inhibited the LPS‐evoked nuclear translocation of NF‐κB in lung tissue. Despite marked efforts, little therapeutic progress has been made, and the mortality rate of ARDS remains high. Vitamin K₃ may be an effective therapeutic strategy against acute lung injury including ARDS.     

Golgi phosphoprotein 3 (GOLPH3) promotes hepatocellular carcinoma cell aggressiveness by activating the NF‐κB pathway

Hepatocellular carcinoma (HCC) is one of the most lethal malignancies, in which the NF‐κB pathway plays an important role and is constitutively activated. Better understanding of the molecular pathogenesis of HCC and the NF‐κB pathway are needed to improve patient outcomes. Herein, we identified an unappreciated protein involved in NF‐κB‐induced activation, Golgi phosphoprotein 3 (GOLPH3). The mRNA and protein expression levels of GOLPH3 were frequently up‐regulated in HCC and GOLPH3 expression correlated closely with clinical stage and survival in both the testing and validation cohorts. Ectopic over‐expression of GOLPH3 in PLC/PRF/5 (PLC) and Huh7 HCC cells protected against cisplatin‐induced apoptosis, promoted angiogenesis and proliferation and increased the aggressiveness of HCC cells in vitro and in vivo, whereas inhibition of GOLPH3 led to decreased aggressiveness. Through analysis of two published HCC patient profiles, GOLPH3 expression significantly correlated with NF‐κB signalling. Furthermore, we demonstrated that GOLPH3 promoted K63‐linked polyubiquitination of tumour necrosis factor receptor‐associated factor 2 (TRAF2), receptor interacting protein (RIP) and NF‐κB essential modulator (NEMO) and substantially sustained the activation of NF‐κB in HCC cells. Taken together, our findings provided evidence that GOLPH3 is a prognostic and/or potential therapeutic biomarker for HCC patients and plays an important role in activation of the NF‐κB pathway during HCC progression. Copyright © 2014 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.     

The Antiproliferation Effect of Berbamine on K562 Resistant Cells by Inhibiting NF‐κB Pathway

Imatinib mesylate is effective against Ph chromosome‐positive leukemia; however, resistance has been reported. High expression of bcr‐abl in mRNA and protein levels, and other alterations were found in patients who experienced imatinib treatment failures and thus it is important to design alternative treatment strategies. The aim of this study was to evaluate the in vitro effect of berbamine, on imatinib‐resistant chronic myelogenous leukemia (CML) K562 (K562‐r) cells, and explore the mechanisms. The growth of K562‐r cells was examined using the 3‐(4,5‐dimethylthiazol‐2yl)‐2,5‐diphenyl‐tetrazolium bromide (MTT) assay. Morphological analysis and DNA agarose electrophoresis were used to detect apoptosis in K562‐r cells, and the extent of the cells in the sub‐G1 cell cycle phase was measured using flow cytometry. The expression levels of BCR‐ABL, phospho‐BCR‐ABL, and nuclear factor κB (NF‐κB), IκBα, phospho‐IκBα, IκB kinases α(IKKα), and Survivin were determined by Western blot. bcr‐abl mRNA expression was determined by RT‐PCR. MTT assays indicated that berbamine significantly inhibited the proliferation of K562‐r cells. Cells with characteristics of apoptosis were confirmed by morphology examination and DNA agarose electrophoresis and percentage of apoptosis were increased after treatment with berbamine. The results also showed that berbamine was able to down‐regulate BCR‐ABL and phospho‐BCR‐ABL proteins by affecting bcr‐abl mRNA expression and decrease expression of nuclear NF‐κB, phospho‐IκBα, IKKα, and Survivin. Collectively, berbamine could inhibit the proliferation of K562‐r cells and induce apoptosis. The mechanisms may be related at least in part, to inhibit BCR‐ABL and its downstream NF‐κB signaling. Berbamine may provide an alternative candidate for the treatment of patients with CML resistant to imatinib therapy. Anat Rec, 292:945–950, 2009. © 2009 Wiley‐Liss, Inc.