IκBβ acts to inhibit and activate gene expression during the inflammatory response

The activation of pro-inflammatory gene programs by nuclear factor-κB (NF-κB) is primarily regulated through cytoplasmic sequestration of NF-κB by the inhibitor of κB (IκB) family of proteins1. IκBβ, a major isoform of IκB, can sequester NF-κB in the cytoplasm2, although its biological role remains unclear. Although cells lacking IκBβ have been reported3, 4, in vivo studies have been limited and suggested redundancy between IκBα and IκBβ5. Like IκBα, IκBβ is also inducibly degraded; however, upon stimulation by lipopolysaccharide (LPS), it is degraded slowly and re-synthesized as a hypophosphorylated form that can be detected in the nucleus6, 7, 8, 9, 10, 11. The crystal structure of IκBβ bound to p65 suggested this complex might bind DNA12. In vitro, hypophosphorylated IκBβ can bind DNA with p65 and c-Rel, and the DNA-bound NF-κB:IκBβ complexes are resistant to IκBα, suggesting hypophosphorylated, nuclear IκBβ may prolong the expression of certain genes9, 10, 11. Here we report that in vivo IκBβ serves both to inhibit and facilitate the inflammatory response. IκBβ degradation releases NF-κB dimers which upregulate pro-inflammatory target genes such as tumour necrosis factor-α (TNF-α). Surprisingly, absence of IκBβ results in a dramatic reduction of TNF-α in response to LPS even though activation of NF-κB is normal. The inhibition of TNF-α messenger RNA (mRNA) expression correlates with the absence of nuclear, hypophosphorylated-IκBβ bound to p65:c-Rel heterodimers at a specific κB site on the TNF-α promoter. Therefore IκBβ acts through p65:c-Rel dimers to maintain prolonged expression of TNF-α. As a result, IκBβ^(−/−) mice are resistant to LPS-induced septic shock and collagen-induced arthritis. Blocking IκBβ might be a promising new strategy for selectively inhibiting the chronic phase of TNF-α production during the inflammatory response

Bladder inflammatory transcriptome in response to tachykinins: Neurokinin 1 receptor-dependent genes and transcription regulatory elements

Background Tachykinins (TK), such as substance P, and their neurokinin receptors which are ubiquitously expressed in the human urinary tract, represent an endogenous system regulating bladder inflammatory, immune responses, and visceral hypersensitivity. Increasing evidence correlates alterations in the TK system with urinary tract diseases such as neurogenic bladders, outflow obstruction, idiopathic detrusor instability, and interstitial cystitis. However, despite promising effects in animal models, there seems to be no published clinical study showing that NK-receptor antagonists are an effective treatment of pain in general or urinary tract disorders, such as detrusor overactivity. In order to search for therapeutic targets that could block the tachykinin system, we set forth to determine the regulatory network downstream of NK1 receptor activation. First, NK1R-dependent transcripts were determined and used to query known databases for their respective transcription regulatory elements (TREs). Methods: An expression analysis was performed using urinary bladders isolated from sensitized wild type (WT) and NK1R-/- mice that were stimulated with saline, LPS, or antigen to provoke inflammation. Based on cDNA array results, NK1R-dependent genes were selected. PAINT software was used to query TRANSFAC database and to retrieve upstream TREs that were confirmed by electrophoretic mobility shift assays. Results: The regulatory network of TREs driving NK1R-dependent genes presented cRel in a central position driving 22% of all genes, followed by AP-1, NF-kappaB, v-Myb, CRE-BP1/c-Jun, USF, Pax-6, Efr-1, Egr-3, and AREB6. A comparison between NK1R-dependent and NK1R-independent genes revealed Nkx-2.5 as a unique discriminator. In the presence of NK1R, Nkx2-5 _01 was significantly correlated with 36 transcripts which included several candidates for mediating bladder development (FGF) and inflammation (PAR-3, IL-1R, IL-6, α-NGF, TSP2). In the absence of NK1R, the matrix Nkx2-5_02 had a predominant participation driving 8 transcripts, which includes those involved in cancer (EYA1, Trail, HSF1, and ELK-1), smooth-to-skeletal muscle trans-differentiation, and Z01, a tight-junction protein, expression. Electrophoretic mobility shift assays confirmed that, in the mouse urinary bladder, activation of NK1R by substance P (SP) induces both NKx-2.5 and NF-kappaB translocations. Conclusion: This is the first report describing a role for Nkx2.5 in the urinary tract. As Nkx2.5 is the unique discriminator of NK1R-modulated inflammation, it can be imagined that in the near future, new based therapies selective for controlling Nkx2.5 activity in the urinary tract may be used in the treatment in a number of bladder disorders

Diminished Telomeric 3′ Overhangs Are Associated with Telomere Dysfunction in Hoyeraal-Hreidarsson Syndrome

BACKGROUND:Eukaryotic chromosomes end with telomeres, which in most organisms are composed of tandem DNA repeats associated with telomeric proteins. These DNA repeats are synthesized by the enzyme telomerase, whose activity in most human tissues is tightly regulated, leading to gradual telomere shortening with cell divisions. Shortening beyond a critical length causes telomere uncapping, manifested by the activation of a DNA damage response (DDR) and consequently cell cycle arrest. Thus, telomere length limits the number of cell divisions and provides a tumor-suppressing mechanism. However, not only telomere shortening, but also damaged telomere structure, can cause telomere uncapping. Dyskeratosis Congenita (DC) and its severe form Hoyeraal-Hreidarsson Syndrome (HHS) are genetic disorders mainly characterized by telomerase deficiency, accelerated telomere shortening, impaired cell proliferation, bone marrow failure, and immunodeficiency. METHODOLOGY/PRINCIPAL FINDINGS:We studied the telomere phenotypes in a family affected with HHS, in which the genes implicated in other cases of DC and HHS have been excluded, and telomerase expression and activity appears to be normal. Telomeres in blood leukocytes derived from the patients were severely short, but in primary fibroblasts they were normal in length. Nevertheless, a significant fraction of telomeres in these fibroblasts activated DDR, an indication of their uncapped state. In addition, the telomeric 3' overhangs are diminished in blood cells and fibroblasts derived from the patients, consistent with a defect in telomere structure common to both cell types. CONCLUSIONS/SIGNIFICANCE:Altogether, these results suggest that the primary defect in these patients lies in the telomere structure, rather than length. We postulate that this defect hinders the access of telomerase to telomeres, thus causing accelerated telomere shortening in blood cells that rely on telomerase to replenish their telomeres. In addition, it activates the DDR and impairs cell proliferation, even in cells with normal telomere length such as fibroblasts. This work demonstrates a telomere length-independent pathway that contributes to a telomere dysfunction disease

Astroglial Inhibition of NF-κB Does Not Ameliorate Disease Onset and Progression in a Mouse Model for Amyotrophic Lateral Sclerosis (ALS)

Motor neuron death in amyotrophic lateral sclerosis (ALS) is considered a “non-cell autonomous” process, with astrocytes playing a critical role in disease progression. Glial cells are activated early in transgenic mice expressing mutant SOD1, suggesting that neuroinflammation has a relevant role in the cascade of events that trigger the death of motor neurons. An inflammatory cascade including COX2 expression, secretion of cytokines and release of NO from astrocytes may descend from activation of a NF-κB-mediated pathway observed in astrocytes from ALS patients and in experimental models. We have attempted rescue of transgenic mutant SOD1 mice through the inhibition of the NF-κB pathway selectively in astrocytes. Here we show that despite efficient inhibition of this major pathway, double transgenic mice expressing the mutant SOD1G93A ubiquitously and the dominant negative form of IκBα (IκBαAA) in astrocytes under control of the GFAP promoter show no benefit in terms of onset and progression of disease. Our data indicate that motor neuron death in ALS cannot be prevented by inhibition of a single inflammatory pathway because alternative pathways are activated in the presence of a persistent toxic stimulus

I kappa B kinase alpha (IKKα) activity is required for functional maturation of dendritic cells and acquired immunity to infection

Dendritic cells (DC) are required for priming antigen-specific T cells and acquired immunity to many important human pathogens, including Mycobacteriuim tuberculosis (TB) and influenza. However, inappropriate priming of auto-reactive T cells is linked with autoimmune disease. Understanding the molecular mechanisms that regulate the priming and activation of naïve T cells is critical for development of new improved vaccines and understanding the pathogenesis of autoimmune diseases. The serine/threonine kinase IKKα (CHUK) has previously been shown to have anti-inflammatory activity and inhibit innate immunity. Here, we show that IKKα is required in DC for priming antigen-specific T cells and acquired immunity to the human pathogen Listeria monocytogenes. We describe a new role for IKKα in regulation of IRF3 activity and the functional maturation of DC. This presents a unique role for IKKα in dampening inflammation while simultaneously promoting adaptive immunity that could have important implications for the development of new vaccine adjuvants and treatment of autoimmune diseases

25-hydroxyvitamin D levels are low but not associated with disease activity in chronic spontaneous urticaria and depression

AIM: To evaluate vitamin D levels in patients with chronic spontaneous urticaria (CSU), depression and both of them, thus to fi nd out whether vitamin D may be a common causative factor of CSU and depression. METHODS: Thirty patients with CSU, 30 patients with depression, 30 patients with both CSU and depression and 30 healthy volunteers as control group were involved in the study. Serum 25-hydroxyvitamin D (25(OH) D) levels of these groups were measured and compared. Correlations between 25(OH)D levels and the activity of CSU and depression were analyzed. RESULTS: Healthy controls' 25(OH)D levels (17.2±8.8 ng/mL) were higher than patients with CSU (9.1±5.1 ng/mL), depression (8.9±6.1 ng/mL) and CSU with depression (7.7±4.7 ng/mL) (p<0.001, p<0.001 and p<0.001, respectively). There were no differences in 25(OH)D levels between CSU patients with and without depression, between depression patients and CSU patients with and without depression (p=0.43, p=0.82 and p=0.92, respectively). There were no correlations between 25(OH)D levels and the activity of CSU or depression (p=0.99 and p=0.76, respectively). CONCLUSION: Lower 25(OH)D levels in CSU and/or depression may appear as a secondary phenomenon, which means being result of these diseases rather than the cause (Tab. 1, Fig. 2, Ref. 41). © 2020 Comenius University.2-s2.0-85090930348PubMed: 3299001

Etude des dépôts calcomagnésiens formés sur acier lors de la protection cathodique : dépôts naturels et dépôts préparés en laboratoire

La protection cathodique est largement utilisée pour préserver les structures métalliques immergées en milieu marin. Cette méthode consiste en la création d'une pile électrochimique constituée d'une part par la structure à protéger (plus noble), qui jouera le rôle de cathode, et d'autre part par un métal moins noble appelé anode sacrificielle. La dissolution des anodes sacrificielles, constituées d'alliages à base de zinc, aluminium ou magnésium entraîne une augmentation de la concentration en ions métalliques dans le milieu. Parallèlement, la réduction de l'oxygène sur la cathode provoque un accroissement du pH à l'interface, ce qui permet la formation de dépôts calcomagnésiens sur la structure ainsi protégée. Cette couche solide crée une barrière diffusionnelle vis à vis de l'oxygène dissous et diminue ainsi le besoin en courant associé à cette protection, ralentissant donc la dissolution de l'anode. Mieux connaître les propriétés physico-chimiques de ces dépôts revient donc à optimiser la protection et diminuer les rejets métalliques provenant des anodes. Au moyen de la diffraction des rayons X, de la microscopie électronique à balayage associée à un spectromètre à dispersion d'énergie, il a été possible de mettre en évidence les différences existant entre dépôts naturellement formés sur site et dépôts obtenus en laboratoire. Constitués de brucite Mg(OH)2 et d'aragonite CaCO3, les dépôts naturels justifient l'appellation "calcomagnésiens". La brucite est observée à l'interface métal/dépôt, sous forme d'inclusions dispersées dans la matrice d'aragonite. En outre, un film à base de minéraux silicatés, dû à la présence de sédiments dans le milieu, se forme sous le dépôt et modifie donc les conditions régnant à l'interface. La formation des dépôts de synthèse, obtenus dans une eau de mer artificielle exempte de sédiments à 20° C, a été suivie par voie électrochimique (chronoampérométrie). Ces dépôts s'avèrent être constitués soit uniquement de brucite, lorsque le potentiel appliqué est très négatif (-1,3 VSCE), soit uniquement d'aragonite, lorsque le potentiel est voisin de ceux habituellement rencontrés pour les aciers protégés cathodiquement (de -1,1 à -0,9 VSCE). Néanmoins, l'étude des premiers stades de la formation du dépôt a permis d'observer la formation, très localisée, d'un composé magnésien. Les causes possibles des différences observées entre dépôts naturels et dépôts de synthèse sont discutées