Wnt/ß-Catenin Signaling Induces Integrin α4ß1 in T Cells and Promotes a Progressive Neuroinflammatory Disease in Mice.

The mechanisms leading to autoimmune and inflammatory diseases in the CNS have not been elucidated. The environmental triggers of the aberrant presence of CD4+ T cells in the CNS are not known. In this article, we report that abnormal ß-catenin expression in T cells drives a fatal neuroinflammatory disease in mice that is characterized by CNS infiltration of T cells, glial activation, and progressive loss of motor function. We show that enhanced ß-catenin expression in T cells leads to aberrant and Th1-biased T cell activation, enhanced expression of integrin α4ß1, and infiltration of activated T cells into the spinal cord, without affecting regulatory T cell function. Importantly, expression of ß-catenin in mature naive T cells was sufficient to drive integrin α4ß1 expression and CNS migration, whereas pharmacologic inhibition of integrin α4ß1 reduced the abnormal T cell presence in the CNS of ß-catenin-expressing mice. Together, these results implicate deregulation of the Wnt/ß-catenin pathway in CNS inflammation and suggest novel therapeutic strategies for neuroinflammatory disorders.

Lack of glucocorticoid-induced leucine zipper (GILZ) deregulates B-cell survival and results in B-cell lymphocytosis in mice.

Glucocorticoids (GC) are widely used as antiinflammatory/immunosuppressive drugs and antitumor agents in several types of lymphoma and leukemia. Therapeutic doses of GC induce growth-suppressive and cytotoxic effects on various leukocytes including B cells. Molecular mechanisms of GC action include induction of GC target genes. Glucocorticoid-induced leucine zipper (GILZ) is a rapidly, potently, and invariably GC-induced gene. It mediates a number of GC effects, such as control of cell proliferation, differentiation, and apoptosis. Here we show that deletion of GILZ in mice leads to an accumulation of B lymphocytes in the bone marrow, blood, and lymphoid tissues. Gilz knockout (KO) mice develop a progressive nonlethal B lymphocytosis, with expansion of B220(+) cells in the bone marrow and in the periphery, dependent on increased B-cell survival. Decreased B-cell apoptosis in mice lacking GILZ correlates with increased NF-κB transcriptional activity and Bcl-2 expression. B cell-specific gilz KO mice confirmed that the effect of GILZ deletion is B-cell self-intrinsic. These results establish GILZ as an important regulator of B-cell survival and suggest that the deregulation of GILZ expression could be implicated in the pathogenesis of B-cell disorders.

Transcriptomics of natural and synthetic vitamin D in human hepatocyte lipotoxicity.

Vitamin D (VD) has been used to prevent nonalcoholic fatty liver disease (NAFLD), a condition of lipotoxicity associated with a defective metabolism and function of this vitamin. Different forms of VD are available and can be used for this scope, but their effects on liver cell lipotoxicity remain unexplored. In this study we compared a natural formulation rich in VD2 (Shiitake Mushroom extract or SM-VD2) with a synthetic formulation containing pure VD3 (SV-VD3) and the bioactive metabolite 1,25(OH)2-D3. These were investigated in chemoprevention mode in human HepaRG liver cells supplemented with oleic and palmitic acid to induce lipotoxicity. All the different forms of VD showed similar efficacy in reducing the levels of lipotoxicity and the changes that lipotoxicity induced on the cellular transcriptome. However, the three forms of VD generated different gene fingerprints suggesting diverse, even if functionally convergent, cytoprotective mechanisms. Main differences were (1) the number of differentially expressed genes (SV-VD3 > 1,25[OH]2-D3 > SM-VD2), (2) their identity that demonstrated significant gene homology between SM-VD2 and 1,25(OH)2-D3, and (3) the number and type of biological functions identified by ingenuity pathway analysis as relevant to liver metabolism and cytoprotection annotations. Immunoblot confirmed a different response of VDR and other VDR-related proteins to natural and synthetic VD formulations, including FXR, PXR, PPARγ/PGC-1α, and CYP3A4 and CYP24A1. In conclusion, different responses of the cellular transcriptome drive the cytoprotective effect of natural and synthetic formulations of VD in the free fatty acid-induced lipotoxicity of human hepatocytes.

Wheat germ oil vitamin E cytoprotective effect and its nutrigenomics signature in human hepatocyte lipotoxicity.

Wheat germ oil (WGO) is rich in α-tocopherol (vitamin E, VE), a vitamin that has long been suggested to exert hepatoprotective effects. In this study, this function of WGO-VE and its transcriptomics fingerprint were investigated in comparison with RRR-α-tocopherol and all-rac-α-tocopherol (nVE and sVE, respectively), in human liver cells treated with oleic acid (OA) to develop steatosis and lipotoxicity. Used in chemoprevention mode, all the VE formulations afforded significant reduction of the OA-induced steatosis and its consequent impact on lipotoxicity indicators, including ROS production and efflux (as H2O2), and apoptotic and necrotic cell death. A trend toward a better control of lipotoxicity was observed for WGO-VE and nVE compared to sVE. Gene microarray data demonstrated that these effects of VE formulations were associated with significantly different responses of the cellular transcriptome to compensate for the modifications of OA treatment, including the downregulation of cellular homeostasis genes and the induction of genes associated with defects of liver cell metabolism, fibrosis and inflammation, liver disease and cancer. Ingenuity Pathway Analysis data showed that WGO-VE modulated genes associated with liver carcinogenesis and steatosis, whereas nVE modulated genes involved in liver cell metabolism and viability biofunctions; sVE did not significantly modulate any gene dataset relevant to such biofunctions. In conclusion, WGO-VE prevents lipotoxicity in human liver cells modulating genes that differ from those affected by the natural or synthetic forms of pure VE. These differences can be captured by precision nutrition tools, reflecting the molecular complexity of this VE-rich extract and its potential in preventing specific cues of hepatocellular lipotoxicity.

Recombinant long-glucocorticoid-induced leucine zipper (L-GILZ) protein restores the control of proliferation in gilz KO spermatogonia.

No genes are yet directly implicated in etiology of male infertility. Identification of genes critical at various stages of spermatogenesis is pivotal for the timely diagnostic and treatment of infertility. We previously found that L-GILZ deficiency in a mouse KO model leads to hyperactivation of Ras signaling and increased proliferation in spermatogonia, resulting in male sterility. The possibility to establish culture cell system that maintains spermatogonial cells in vitro allowed us to delivery a recombinant protein TAT-L-GILZ able to restore normal proliferation rate in gilz KO spermatogonia. We also found that N-terminal part of L-GILZ protein is responsible for Ras/L-GILZ protein-to-protein interaction, important for the control of proliferation rate of spermatogonia. Therefore, treatments increasing L-GILZ expression, such as delivering small molecules or peptides that mimic L-GILZ functions, are approaches with great potential of applicability for new therapeutic strategies based on gene/protein delivery to the affected testes.

GILZ promotes production of peripherally induced Treg cells and mediates the crosstalk between glucocorticoids and TGF-ß signaling.

Regulatory T (Treg) cells expressing the transcription factor forkhead box P3 (FoxP3) control immune responses and prevent autoimmunity. Treatment with glucocorticoids (GCs) has been shown to increase Treg cell frequency, but the mechanisms of their action on Treg cell induction are largely unknown. Here, we report that glucocorticoid-induced leucine zipper (GILZ), a protein induced by GCs, promotes Treg cell production. In mice, GILZ overexpression causes an increase in Treg cell number, whereas GILZ deficiency results in impaired generation of peripheral Treg cells (pTreg), associated with increased spontaneous and experimental intestinal inflammation. Mechanistically, we found that GILZ is required for GCs to cooperate with TGF-ß in FoxP3 induction, while it enhances TGF-ß signaling by binding to and promoting Smad2 phosphorylation and activation of FoxP3 expression. Thus, our results establish an essential GILZ-mediated link between the anti-inflammatory action of GCs and the regulation of TGF-ß-dependent pTreg production.