NEMO differentially regulates TCR and TNF-α induced NF-κB pathways and has an inhibitory role in TCR-induced NF-κB activation

Transcriptional investigation of the toxic mechanisms of perfluorooctane sulfonate in rats based on an RNA-Seq approach

Perfluorooctane sulfonate (PFOS) was widely used in industrial applications before it was listed as a persistent organic pollutant by the Conference of the Parties in the Stockholm Convention in 2009. Although the potential toxicity of PFOS has been studied, its toxic mechanisms remain largely undefined. Here, we investigated novel hub genes and pathways affected by PFOS to gain new conceptions of the toxic mechanisms of PFOS. Reduced body weight gain and abnormal ultra-structures in the liver and kidney tissues were spotted in PFOS-exposed rats, indicating successful establishment of the PFOS-exposed rat model. The transcriptomic alterations of blood samples upon PFOS exposure were analysed using RNA-Seq. GO analysis indicates that the differentially expressed gene-enriched GO terms are related to metabolism, cellular processes, and biological regulation. Kyoto encyclopaedia of gene and genomes (KEGG) and gene set enrichment analysis (GSEA) were conducted to identify six key pathways: spliceosome, B cell receptor signalling pathway, acute myeloid leukaemia, protein processing in the endoplasmic reticulum, NF-kappa B signalling pathway, and Fc gamma R-mediated phagocytosis. The top 10 hub genes were screened from a protein-protein interaction network and verified via quantitative real-time polymerase chain reaction. The overall pathway network and hub genes may provide new insights into the toxic mechanisms of PFOS exposure states.

Inflammatory Bowel Disease: A Review of Pre-Clinical Murine Models of Human Disease

Crohn’s disease (CD) and ulcerative colitis (UC) are both highly inflammatory diseases of the gastrointestinal tract, collectively known as inflammatory bowel disease (IBD). Although the cause of IBD is still unclear, several experimental IBD murine models have enabled researchers to make great inroads into understanding human IBD pathology. Here, we discuss the current pre-clinical experimental murine models for human IBD, including the chemical-induced trinitrobenzene sulfonic acid (TNBS) model, oxazolone and dextran sulphate sodium (DSS) models, the gene-deficient I-kappa-B kinase gamma (Iκκ-γ) and interleukin(IL)-10 models, and the CD4⁺ T-cell transfer model. We offer a comprehensive review of how these models have been used to dissect the etiopathogenesis of disease, alongside their limitations. Furthermore, the way in which this knowledge has led to the translation of experimental findings into novel clinical therapeutics is also discussed.

Gene expression regulated by abatacept associated with methotrexate and correlation with disease activity in rheumatoid arthritis

Objectives

Abatacept acts as a competitive inhibitor of the CD28/(CD80/86) costimulation signal required for T cell activation. Mechanisms of action of abatacept have not been fully investigated. The objective of this study was to provide detailed insight into the mode of action of Abatacept based on gene expression data.

Methods

In this ancillary study from the APPRAISE trial, we investigated the global molecular effects of Abatacept in whole blood samples collected prospectively in biologic naive rheumatoid arthritis patients (n = 19) at baseline and 6 months after the initiation of Abatacept therapy concomitant with methotrexate. Whole human genome microarrays (4x44K) were performed on both baseline and 6-month samples from responders and non-responders patients categorized according to EULAR criteria. T-test with Benjamini-Hochberg correction was performed to identify significant gene expression changes. Gene Ontology and Single Experiment Analysis tools allowed us to highlight specific biological mechanisms involved in methotrexate/Abatacept.

Results

In methotrexate/Abatacept responders, 672 genes were significantly (q<0.05) dysregulated at 6 months compared to baseline. Correlation analysis highlighted 19 genes whose dysregulations were significantly associated with disease activity variation (p<0.05) and whose functions were associated with proliferation, apoptosis of cells and mitochondrial metabolism, suggesting a restoration of oxidative signaling. The other 653 gene expression changes were relative to direct or indirect effects of methotrexate/Abatacept treatment and were significantly (p<0.005) involved in pathways relative to mRNA processing, proteasome, angiogenesis, apoptosis and TCR signaling. This study highlights new mechanisms of action of methotrexate/Abatacept and may provide new therapeutic targets to prevent autoimmunity in rheumatoid arthritis.

MicroRNA-181a-5p and microRNA-181a-3p cooperatively restrict vascular inflammation and atherosclerosis

MicroRNAs have emerged as important post-transcriptional regulators of gene expression and are involved in diverse diseases and cellular process. Decreased expression of miR-181a has been observed in the patients with coronary artery disease, but its function and mechanism in atherogenesis is not clear. This study was designed to determine the roles of miR-181a-5p, as well as its passenger strand, miR-181a-3p, in vascular inflammation and atherogenesis. We found that the levels of both miR-181a-5p and miR-181a-3p are decreased in the aorta plaque and plasma of apoE^−/− mice in response to hyperlipidemia and in the plasma of patients with coronary artery disease. Rescue of miR-181a-5p and miR-181a-3p significantly retards atherosclerotic plaque formation in apoE^−/− mice. MiR-181a-5p and miR-181a-3p have no effect on lipid metabolism but decrease proinflammatory gene expression and the infiltration of macrophage, leukocyte and T cell into the lesions. In addition, gain-of-function and loss-of-function experiments show that miR-181a-5p and miR-181a-3p inhibit adhesion molecule expression in HUVECs and monocytes-endothelial cell interaction. MiR-181a-5p and miR-181a-3p cooperatively receded endothelium inflammation compared with single miRNA strand. Mechanistically, miR-181a-5p and miR-181a-3p prevent endothelial cell activation through blockade of NF-κB signaling pathway by targeting TAB2 and NEMO, respectively. In conclusion, these findings suggest that miR-181a-5p and miR-181a-3p are both antiatherogenic miRNAs. MiR-181a-5p and miR-181a-3p mimetics retard atherosclerosis progression through blocking NF-κB activation and vascular inflammation by targeting TAB2 and NEMO, respectively. Therefore, restoration of miR-181a-5p and miR-181a-3p may represent a novel therapeutic approach to manage atherosclerosis.

T-lymphocyte-specific knockout of IKK-2 or NEMO induces Th17 cells in an experimental nephrotoxic nephritis mouse model

Experimental nephrotoxic serum nephritis (NTN) is a model for T-cell-mediated human rapid progressive glomerulonephritis. T-cell receptor stimulation involves intracellular signaling events that ultimately lead to the activation of transcription factors, such as NF-κB. We explored the involvement of the NF-κB components IKK-2 and NEMO in NTN, by using cell-specific knockouts of IKK-2 and NEMO in CD4⁺ T lymphocytes. Our results demonstrate that although the course of disease was not grossly altered in CD4xIKK2^Δ and CD4xNEMO^Δ animals, renal regulatory T cells were significantly reduced and T helper (T_h)1 and T_h17 cells significantly increased in both knockout mouse groups. The expression of the renal cytokines and chemokines IL-1β, CCL-2, and CCL-20 was also significantly altered in both knockout mice. Lymphocyte transcriptome analysis confirmed the increased expression of T_h17-related cytokines in spleen CD4⁺ T cells. Moreover, our array data demonstrate an interrupted canonical NF-κB pathway and an increased expression of noncanonical NF-κB pathway-related genes in nephritic CD4xNEMO^Δ mice, highlighting different downstream effects of deletion of IKK-2 or NEMO in T lymphocytes. We propose that better understanding of the role of IKK-2 and NEMO in nephritis is essential for the clinical application of kinase inhibitors in patients with glomerulonephritis.-Guo, L., Huang, J., Chen, M., Piotrowski, E., Song, N., Zahner, G., Paust, H.-J., Alawi, M., Geffers, R., Thaiss, F. T-lymphocyte-specific knockout of IKK-2 or NEMO induces T_h17 cells in an experimental nephrotoxic nephritis mouse model.

Decreased expression of WNT2 in villi of unexplained recurrent spontaneous abortion patients may cause trophoblast cell dysfunction via downregulated Wnt/β-catenin signaling pathway

WNT2 has been reported to be important for placental development, especially for the proper vascularization of the placenta. However, its precise role in first-trimester trophoblast cells is still unknown. WNT2 expression in the villous tissues of unexplained recurrent spontaneous abortion (URSA) patients was compared with that of healthy women by Western blot. The function of WNT2 in HTR-8/SVneo trophoblast cells was evaluated by altering the cellular WNT2 level through overexpression and shRNA knockdown. The molecular mechanism of the effect of WNT2 on trophoblast cells was investigated. The association of WNT2 with the Wnt/β-catenin signaling pathway was studied through Western blot and immunofluorescence. Results showed that WNT2 protein expression was significantly decreased in villi of the URSA group compared with the control group. In vitro studies showed that WNT2 could promote human trophoblast cell proliferation and migration through activating the Wnt/β-catenin signaling pathway. Moreover, upon the knockdown of WNT2, trophoblast cell proliferation and migration were significantly suppressed. In conclusion, our study indicated that WNT2 plays an important role in trophoblast function. WNT2 insufficiency might cause impaired trophoblast cell proliferation and migration via downregulation of Wnt/β-catenin signaling pathway.

Antioxidant and anti-inflammatory effects of zinc. Zinc-dependent NF-κB signaling

Zinc is a nutritionally fundamental trace element, essential to the structure and function of numerous macromolecules, including enzymes regulating cellular processes and cellular signaling pathways. The mineral modulates immune response and exhibits antioxidant and anti-inflammatory activity. Zinc retards oxidative processes on a long-term basis by inducing the expression of metallothioneins. These metal-binding cysteine-rich proteins are responsible for maintaining zinc-related cell homeostasis and act as potent electrophilic scavengers and cytoprotective agents. Furthermore, zinc increases the activation of antioxidant proteins and enzymes, such as glutathione and catalase. On the other hand, zinc exerts its antioxidant effect via two acute mechanisms, one of which is the stabilization of protein sulfhydryls against oxidation. The second mechanism consists in antagonizing transition metal-catalyzed reactions. Zinc can exchange redox active metals, such as copper and iron, in certain binding sites and attenuate cellular site-specific oxidative injury. Studies have demonstrated that physiological reconstitution of zinc restrains immune activation, whereas zinc deficiency, in the setting of severe infection, provokes a systemic increase in NF-κB activation. In vitro studies have shown that zinc decreases NF-κB activation and its target genes, such as TNF-α and IL-1β, and increases the gene expression of A20 and PPAR-α, the two zinc finger proteins with anti-inflammatory properties. Alternative NF-κB inhibitory mechanism is initiated by the inhibition of cyclic nucleotide phosphodiesterase, whereas another presumed mechanism consists in inhibition of IκB kinase in response to infection by zinc ions that have been imported into cells by ZIP8.

Comparison of gene expression of the oncogenic Wnt/β-catenin signaling pathway components in the mouse and human epididymis

β-catenin is an integral part of the Wnt signaling pathway and has been linked to tumorigenesis and multiple developmental processes. The high β-catenin expression with low tumor incidence in the human epididymis is thus intriguing. In the present study, the β-catenin gene and protein was found to be highly expressed in the murine caput epididymidis, and the protein mainly localized along the lateral plasma membranes of adjacent epithelial cells throughout both human and mouse epididymides. Furthermore, the adult mouse epididymis was found to express almost all the Wnt/β-catenin signaling pathway genes that were determined previously by our group in the human organ. Despite the differences in epididymal structure, the similar location of β-catenin and the high concordance of this pathway's components’ gene expression in both the adult human and mouse epididymides make the mouse a suitable animal model for studying the anti-tumor mechanism of the epididymis. In addition, both the mRNA and protein expression of β-catenin shared a similar spatial expression as the mRNA of Ros1, a proto-oncogene and a key developmental regulator of the initial segment of the mouse epididymis. The observations on the parallel temporal expression of β-catenin and Ros1 during postnatal development raise the possibility that the canonical Wnt signaling pathway has an additional role in the postnatal development of mouse epididymis.

The activation of pyrin domain-containing-3 inflammasome depends on lipopolysaccharide from Porphyromonas gingivalis and extracellular adenosine triphosphate in cultured oral epithelial cells

Background

Gingival epithelial cells are the major population of the gingival tissue, acting as the front-line defense against microbial intrusion and regulating the homeostasis of the periodontal tissue in health and disease via NLR family pyrin domain-containing-3 (NLRP3) inflammasome, which recognizes pathogen- and danger-associated molecular patterns (PAMPs and DAMPs). The aim of this study was to determine whether the activation of NLRP3 inflammasome depends on infection with the periodontal pathogen Porphyromonas gingivalis (P. gingivalis), or stimulation with P. gingivalis lipopolysaccharide (LPS), and/or extracellular adenosine triphosphate (ATP).

Methods

An oral epithelial cell line was treated with P. gingivalis, P. gingivalis LPS and ATP. The gene and protein expression of NLRP3 inflammasome components were quantified by real time RT-PCR and immunoblots. Production of IL-1β and IL-18 was measured by ELISA.

Results

There was no increase in NLRP3 inflammasome gene expression after P. gingivalis infection unless pre-stimulated by ATP. Obvious increases of NLRP3 inflammasome gene expression was observed after P. gingivalis LPS stimulation, even pre-stimulated by ATP at 2 h.

Conclusions

The findings indicate that the activation of NLRP3 inflammasome does not rely on P. gingivalis infection, unless stimulated by P. gingivalis LPS and/or extracellular ATP, suggesting diverse signaling pathways are involved in the host immune response.