Epigenome-wide analysis reveals functional modulators of drug sensitivity and post-treatment survival in chronic lymphocytic leukaemia.

BACKGROUND: Chronic lymphocytic leukaemia (CLL) patients display a highly variable clinical course, with progressive acquisition of drug resistance. We sought to identify aberrant epigenetic traits that are enriched following exposure to treatment that could impact patient response to therapy. METHODS: Epigenome-wide analysis of DNA methylation was performed for 20 patients at two timepoints during treatment. The prognostic significance of differentially methylated regions (DMRs) was assessed in independent cohorts of 139 and 163 patients. Their functional role in drug sensitivity was assessed in vitro. RESULTS: We identified 490 DMRs following exposure to therapy, of which 31 were CLL-specific and independent of changes occurring in normal B-cell development. Seventeen DMR-associated genes were identified as differentially expressed following treatment in an independent cohort. Methylation of the HOXA4, MAFB and SLCO3A1 DMRs was associated with post-treatment patient survival, with HOXA4 displaying the strongest association. Re-expression of HOXA4 in cell lines and primary CLL cells significantly increased apoptosis in response to treatment with fludarabine, ibrutinib and idelalisib. CONCLUSION: Our study demonstrates enrichment for multiple CLL-specific epigenetic traits in response to chemotherapy that predict patient outcomes, and particularly implicate epigenetic silencing of HOXA4 in reducing the sensitivity of CLL cells to therapy.

Opposite effects of a glucokinase activator and metformin on glucose-regulated gene expression in hepatocytes.

AIM: Small molecule activators of glucokinase (GKAs) have been explored extensively as potential anti-hyperglycaemic drugs for type 2 diabetes (T2D). Several GKAs were remarkably effective in lowering blood glucose during early therapy but then lost their glycaemic efficacy chronically during clinical trials. MATERIALS AND METHODS: We used rat hepatocytes to test the hypothesis that GKAs raise hepatocyte glucose 6-phosphate (G6P, the glucokinase product) and down-stream metabolites with consequent repression of the liver glucokinase gene ( Gck). We compared a GKA with metformin, the most widely prescribed drug for T2D. RESULTS: Treatment of hepatocytes with 25 mM glucose raised cell G6P, concomitantly with Gck repression and induction of G6pc (glucose 6-phosphatase) and Pklr (pyruvate kinase). A GKA mimicked high glucose by raising G6P and fructose-2,6-bisphosphate, a regulatory metabolite, causing a left-shift in glucose responsiveness on gene regulation. Fructose, like the GKA, repressed Gck but modestly induced G6pc. 2-Deoxyglucose, which is phosphorylated by glucokinase but not further metabolized caused Gck repression but not G6pc induction, implicating the glucokinase product in Gck repression. Metformin counteracted the effect of high glucose on the elevated G6P and fructose 2,6-bisphosphate and on Gck repression, recruitment of Mlx-ChREBP to the G6pc and Pklr promoters and induction of these genes. CONCLUSIONS: Elevation in hepatocyte G6P and downstream metabolites, with consequent liver Gck repression, is a potential contributing mechanism to the loss of GKA efficacy during chronic therapy. Cell metformin loads within the therapeutic range attenuate the effect of high glucose on G6P and on glucose-regulated gene expression.

Regulation of p53 and Rb links the alternative NF-κB pathway to EZH2 expression and cell senescence.

There are two major pathways leading to induction of NF-κB subunits. The classical (or canonical) pathway typically leads to the induction of RelA or c-Rel containing complexes, and involves the degradation of IκBα in a manner dependent on IκB kinase (IKK) ß and the IKK regulatory subunit NEMO. The alternative (or non-canonical) pathway, involves the inducible processing of p100 to p52, leading to the induction of NF-κB2(p52)/RelB containing complexes, and is dependent on IKKα and NF-κB inducing kinase (NIK). Here we demonstrate that in primary human fibroblasts, the alternative NF-κB pathway subunits NF-κB2 and RelB have multiple, but distinct, effects on the expression of key regulators of the cell cycle, reactive oxygen species (ROS) generation and protein stability. Specifically, following siRNA knockdown, quantitative PCR, western blot analyses and chromatin immunoprecipitation (ChIP) show that NF-κB2 regulates the expression of CDK4 and CDK6, while RelB, through the regulation of genes such as PSMA5 and ANAPC1, regulates the stability of p21WAF1 and the tumour suppressor p53. These combine to regulate the activity of the retinoblastoma protein, Rb, leading to induction of polycomb protein EZH2 expression. Moreover, our ChIP analysis demonstrates that EZH2 is also a direct NF-κB target gene. Microarray analysis revealed that in fibroblasts, EZH2 antagonizes a subset of p53 target genes previously associated with the senescent cell phenotype, including DEK and RacGAP1. We show that this pathway provides the major route of crosstalk between the alternative NF-κB pathway and p53, a consequence of which is to suppress cell senescence. Importantly, we find that activation of NF-κB also induces EZH2 expression in CD40L stimulated cells from Chronic Lymphocytic Leukemia patients. We therefore propose that this pathway provides a mechanism through which microenvironment induced NF-κB can inhibit tumor suppressor function and promote tumorigenesis.

Enhanced monocyte migration to CXCR3 and CCR5 chemokines in COPD.

Chronic obstructive pulmonary disease (COPD) patients exhibit chronic inflammation, both in the lung parenchyma and the airways, which is characterised by an increased infiltration of macrophages and T-lymphocytes, particularly CD8+ cells. Both cell types can express chemokine (C-X-C motif) receptor (CXCR)3 and C-C chemokine receptor 5 and the relevant chemokines for these receptors are elevated in COPD. The aim of this study was to compare chemotactic responses of lymphocytes and monocytes of nonsmokers, smokers and COPD patients towards CXCR3 ligands and chemokine (C-C motif) ligand (CCL)5. Migration of peripheral blood mononuclear cells, monocytes and lymphocytes from nonsmokers, smokers and COPD patients toward CXCR3 chemokines and CCL5 was analysed using chemotaxis assays. There was increased migration of peripheral blood mononuclear cells from COPD patients towards all chemokines studied when compared with nonsmokers and smokers. Both lymphocytes and monocytes contributed to this enhanced response, which was not explained by increased receptor expression. However, isolated lymphocytes failed to migrate and isolated monocytes from COPD patients lost their enhanced migratory capacity. Both monocytes and lymphocytes cooperate to enhance migration towards CXCR3 chemokines and CCL5. This may contribute to increased numbers of macrophages and T-cells in the lungs of COPD patients, and inhibition of recruitment using selective antagonists might be a treatment to reduce the inflammatory response in COPD.

Fructose 2,6-bisphosphate is essential for glucose-regulated gene transcription of glucose-6-phosphatase and other ChREBP target genes in hepatocytes.

Glucose metabolism in the liver activates the transcription of various genes encoding enzymes of glycolysis and lipogenesis and also G6pc (glucose-6-phosphatase). Allosteric mechanisms involving glucose 6-phosphate or xylulose 5-phosphate and covalent modification of ChREBP (carbohydrate-response element-binding protein) have been implicated in this mechanism. However, evidence supporting an essential role for a specific metabolite or pathway in hepatocytes remains equivocal. By using diverse substrates and inhibitors and a kinase-deficient bisphosphatase-active variant of the bifunctional enzyme PFK2/FBP2 (6-phosphofructo-2-kinase-fructose-2,6-bisphosphatase), we demonstrate an essential role for fructose 2,6-bisphosphate in the induction of G6pc and other ChREBP target genes by glucose. Selective depletion of fructose 2,6-bisphosphate inhibits glucose-induced recruitment of ChREBP to the G6pc promoter and also induction of G6pc by xylitol and gluconeogenic precursors. The requirement for fructose 2,6-bisphosphate for ChREBP recruitment to the promoter does not exclude the involvement of additional metabolites acting either co-ordinately or at downstream sites. Glucose raises fructose 2,6-bisphosphate levels in hepatocytes by reversing the phosphorylation of PFK2/FBP2 at Ser32, but also independently of Ser32 dephosphorylation. This supports a role for the bifunctional enzyme as the phosphometabolite sensor and for its product, fructose 2,6-bisphosphate, as the metabolic signal for substrate-regulated ChREBP-mediated expression of G6pc and other ChREBP target genes.

Fragment expansion with NUDELs - poised DNA-encoded libraries.

Optimisation of the affinity of lead compounds is a critical challenge in the identification of drug candidates and chemical probes and is a process that takes many years. Fragment-based drug discovery has become established as one of the methods of choice for drug discovery starting with small, low affinity compounds. Due to their low affinity, the evolution of fragments to desirable levels of affinity is often a key challenge. The accepted best method for increasing the potency of fragments is by iterative fragment growing, which can be very time consuming and complex. Here, we introduce a paradigm for fragment hit optimisation using poised DNA-encoded chemical libraries (DELs). The synthesis of a poised DEL, a partially constructed library that retains a reactive handle, allows the coupling of any active fragment for a specific target protein, allowing rapid discovery of potent ligands. This is illustrated for bromodomain-containing protein 4 (BRD4), in which a weakly binding fragment was coupled to a 42-member poised DEL via Suzuki-Miyaura cross coupling resulting in the identification of an inhibitor with 51 nM affinity in a single step, representing an increase in potency of several orders of magnitude from an original fragment. The potency of the compound was shown to arise from the synergistic combination of substructures, which would have been very difficult to discover by any other method and was rationalised by X-ray crystallography. The compound showed attractive lead-like properties suitable for further optimisation and demonstrated BRD4-dependent cellular pharmacology. This work demonstrates the power of poised DELs to rapidly optimise fragments, representing an attractive generic approach to drug discovery.

Expression and Activity of the NF-κB Subunits in Chronic Lymphocytic Leukaemia: A Role for RelB and Non-Canonical Signalling.

BACKGROUND: Canonical NF-κB signalling by p65 (RelA) confers chemo-resistance and poor survival in chronic lymphocytic leukaemia (CLL). The role of non-canonical NF-κB signalling (leading to RelB and p52 subunit activation) in CLL is less understood, but given its importance in other B-cell tumour types, we theorised that RelB and p52 may also contribute to the pathology of CLL. METHODS: DNA binding activity of all five NF-kB subunits, p65, p50, RelB, p52, and c-Rel, was quantified using ELISA and correlated to ex vivo chemoresistance, CD40L-stimulated signalling (to mimic the lymph node microenvironment), and clinical data. RESULTS: Importantly, we show for the first time that high basal levels of RelB DNA binding correlate with nuclear RelB protein expression and are associated with del(11q), ATM dysfunction, unmutated IGHV genes, and shorter survival. High levels of nuclear p65 are prevalent in del(17p) cases (including treatment-naïve patients) and also correlate with the outcome. CD40L-stimulation resulted in rapid RelB activation, phosphorylation and processing of p100, and subsequent CLL cell proliferation. CONCLUSIONS: These data highlight a role for RelB in driving CLL cell tumour growth in a subset of patients and therefore strategies designed to inhibit non-canonical NF-κB signalling represent a novel approach that will have therapeutic benefit in CLL.

Regulation of IL-17 in chronic inflammation in the human lung.

The regulation of human Th17 cell effector function by Treg cells (regulatory T-cells) is poorly understood. In the present study, we report that human Treg (CD4(+)CD25(+)) cells inhibit the proliferative response of Th17 cells but not their capacity to secrete IL (interleukin)-17. However, they could inhibit proliferation and cytokine production by Th1 and Th2 cells as determined by IFN-γ (interferon-γ) and IL-5 biosynthesis. Currently, as there is interest in the role of IL-17-producing cells and Treg cells in chronic inflammatory diseases in humans, we investigated the presence of CD4(+)CD25(+) T-cells and IL-17 in inflammation in the human lung. Transcripts for IL-17 were expressed in mononuclear cells and purified T-cells from lung tissue of patients with chronic pulmonary inflammation and, when activated, these cells secrete soluble protein. The T-cell-specific transcription factors RORCv2 (retinoic acid-related orphan receptor Cv2; for Th17) and FOXP3 (forkhead box P3; for Treg cells) were enriched in the T-cell fraction of lung mononuclear cells. Retrospective stratification of the patient cohort into those with COPD (chronic obstructive pulmonary disease) and non-COPD lung disease revealed no difference in the expression of IL-17 and IL-23 receptor between the groups. We observed that CD4(+)CD25(+) T-cells were present in comparable numbers in COPD and non-COPD lung tissue and with no correlation between the presence of CD4(+)CD25(+) T-cells and IL-17-producing cells. These results suggest that IL-17-expressing cells are present in chronically inflamed lung tissue, but there is no evidence to support this is due to the recruitment or expansion of Treg cells.

An Alkynylpyrimidine-Based Covalent Inhibitor That Targets a Unique Cysteine in NF-κB-Inducing Kinase.

NF-κB-inducing kinase (NIK) is a key enzyme in the noncanonical NF-κB pathway, of interest in the treatment of a variety of diseases including cancer. Validation of NIK as a drug target requires potent and selective inhibitors. The protein contains a cysteine residue at position 444 in the back pocket of the active site, unique within the kinome. Analysis of existing inhibitor scaffolds and early structure-activity relationships (SARs) led to the design of C444-targeting covalent inhibitors based on alkynyl heterocycle warheads. Mass spectrometry provided proof of the covalent mechanism, and the SAR was rationalized by computational modeling. Profiling of more potent analogues in tumor cell lines with constitutively activated NIK signaling induced a weak antiproliferative effect, suggesting that kinase inhibition may have limited impact on cancer cell growth. This study shows that alkynyl heterocycles are potential cysteine traps, which may be employed where common Michael acceptors, such as acrylamides, are not tolerated.

Profound invariant natural killer T-cell deficiency in inflammatory arthritis.

OBJECTIVES: Data from rodent models indicate that invariant natural killer T (iNKT) cells are key regulators of many immune responses including autoimmune arthritis, but their role in human diseases is unclear. The aims of this study are to determine whether iNKT cell frequency and function are altered in patients with rheumatoid arthritis (RA), and the clinical significance of such iNKT cell abnormalities. METHODS: Peripheral blood iNKT cell frequency and proliferative response to an iNKT cell-specific agonist, α-galactosylceramide were measured in 46 RA patients (including 23 untreated, newly diagnosed patients), 22 healthy controls and 27 patients presenting with recent-onset joint pain. The relationship between iNKT cell frequency and clinical characteristics and the effects of immunosuppressive treatment was examined. RESULTS: Compared with healthy controls, RA patients had a decreased frequency of peripheral blood iNKT cells (median 0.001% vs 0.021%, p<0.001) and the proliferative response of this subset to α-galactosylceramide was also diminished in the patient group (median fold-expansion 31 vs 121, p=0.037). These abnormalities preceded the initiation of disease-modifying or immunosuppressive therapy, whose effect was to increase the circulating iNKT cell frequency (p=0.037). Furthermore, iNKT cell frequency correlated inversely with the systemic inflammatory marker, C-reactive protein (p=0.008). Finally, in patients presenting with recent-onset joint symptoms, normal peripheral blood iNKT cell frequency predicted a non-inflammatory cause of joint pain. CONCLUSION: iNKT cell deficiency is present in patients with RA and other inflammatory arthropathy. Normal iNKT cell frequency predicts non-inflammatory causes of joint pain.

Selective DNA-PKcs inhibition extends the therapeutic index of localized radiotherapy and chemotherapy.

Potentiating radiotherapy and chemotherapy by inhibiting DNA damage repair is proposed as a therapeutic strategy to improve outcomes for patients with solid tumors. However, this approach risks enhancing normal tissue toxicity as much as tumor toxicity, thereby limiting its translational impact. Using NU5455, a newly identified highly selective oral inhibitor of DNA-dependent protein kinase catalytic subunit (DNA-PKcs) activity, we found that it was indeed possible to preferentially augment the effect of targeted radiotherapy on human orthotopic lung tumors without influencing acute DNA damage or a late radiation-induced toxicity (fibrosis) to normal mouse lung. Furthermore, while NU5455 administration increased both the efficacy and the toxicity of a parenterally administered topoisomerase inhibitor, it enhanced the activity of doxorubicin released locally in liver tumor xenografts without inducing any adverse effect. This strategy is particularly relevant to hepatocellular cancer, which is treated clinically with localized drug-eluting beads and for which DNA-PKcs activity is reported to confer resistance to treatment. We conclude that transient pharmacological inhibition of DNA-PKcs activity is effective and tolerable when combined with localized DNA-damaging therapies and thus has promising clinical potential.

Different mitogen-activated protein kinase-dependent cytokine responses in cells of the monocyte lineage.

Macrophages release cytokines that may contribute to the chronic inflammation observed in pulmonary conditions such as asthma and chronic obstructive pulmonary disease. Thus, inhibition of macrophage cytokine production may have a therapeutic benefit. Human lung macrophages are a rich source of the proinflammatory cytokines, tumor necrosis factor (TNF)-alpha, granulocyte macrophage colony-stimulating factor (GM-CSF), interleukin (IL)-6, and IL-8, that are elevated in the bronchoalveolar lavage and sputum of subjects with respiratory diseases. Cytokine production from both monocytes and macrophages is mediated by mitogen-activated protein kinase (MAPK) pathways. This study compared the effects of a novel p38 MAPK inhibitor, N-cyano-N'-(2-{[8-(2,6-difluorophenyl)-4-(4-fluoro-2-methylphenyl)-7-oxo-7,8-dihydropyrido[2,3-d]pyrimidin-2-yl]amino}ethyl)-guanidine (PCG), and an extracellular signal-regulated kinase (ERK) pathway inhibitor, 2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one (PD098059), on cytokine release from lipopolysaccharide (LPS)-stimulated human monocytes, monocyte-derived macrophages (MDM), and lung macrophages. Lung macrophages, MDM, and monocytes were stimulated with LPS, and cytokine release was measured by enzyme-linked immunosorbent assay. Immunoblots were performed to confirm p38 and ERK1/2 MAPK expression and activity. PCG inhibited TNF-alpha release more effectively from monocytes compared with MDM or macrophages (maximal inhibition was 99.3 +/- 1.4, 62.7 +/- 4.3, and 58.6 +/- 6.6%, respectively; n = 7-9). PD098059 was less effective at suppressing TNF-alpha release from monocytes compared with MDM and lung macrophages (maximal inhibition was 37.4 +/- 2.8, 70.1 +/- 4.5, and 68.7 +/- 5.1%, respectively; n = 7-9). The pattern of GM-CSF, IL-6, and IL-8 release was comparable with that of TNF-alpha. These data suggest a differential involvement for each of these MAPK pathways in macrophage cytokine production compared with monocytes.

Cyclin-Dependent Kinase (CDK) Inhibitors: Structure-Activity Relationships and Insights into the CDK-2 Selectivity of 6-Substituted 2-Arylaminopurines.

Purines and related heterocycles substituted at C-2 with 4'-sulfamoylanilino and at C-6 with a variety of groups have been synthesized with the aim of achieving selectivity of binding to CDK2 over CDK1. 6-Substituents that favor competitive inhibition at the ATP binding site of CDK2 were identified and typically exhibited 10-80-fold greater inhibition of CDK2 compared to CDK1. Most impressive was 4-((6-([1,1'-biphenyl]-3-yl)-9H-purin-2-yl)amino) benzenesulfonamide (73) that exhibited high potency toward CDK2 (IC50 0.044 µM) but was ∼2000-fold less active toward CDK1 (IC50 86 µM). This compound is therefore a useful tool for studies of cell cycle regulation. Crystal structures of inhibitor-kinase complexes showed that the inhibitor stabilizes a glycine-rich loop conformation that shapes the ATP ribose binding pocket and that is preferred in CDK2 but has not been observed in CDK1. This aspect of the active site may be exploited for the design of inhibitors that distinguish between CDK1 and CDK2.

PARP1 expression, activity and ex vivo sensitivity to the PARP inhibitor, talazoparib (BMN 673), in chronic lymphocytic leukaemia.

In chronic lymphocytic leukemia (CLL), mutation and loss of p53 and ATM abrogate DNA damage signalling and predict poorer response and shorter survival. We hypothesised that poly (ADP-ribose) polymerase (PARP) activity, which is crucial for repair of DNA breaks induced by oxidative stress or chemotherapy, may be an additional predictive biomarker and a target for therapy with PARP inhibitors.We measured PARP activity in 109 patient-derived CLL samples, which varied widely (192 - 190052 pmol PAR/106 cells) compared to that seen in healthy volunteer lymphocytes (2451 - 7519 pmol PAR/106 cells). PARP activity was associated with PARP1 protein expression and endogenous PAR levels. PARP activity was not associated with p53 or ATM loss, Binet stage, IGHV mutational status or survival, but correlated with Bcl-2 and Rel A (an NF-kB subunit). Levels of 8-hydroxy-2'-deoxyguanosine in DNA (a marker of oxidative damage) were not associated with PAR levels or PARP activity. The potent PARP inhibitor, talazoparib (BMN 673), inhibited CD40L-stimulated proliferation of CLL cells at nM concentrations, independently of Binet stage or p53/ATM function.PARP activity is highly variable in CLL and correlates with stress-induced proteins. Proliferating CLL cells (including those with p53 or ATM loss) are highly sensitive to the PARP inhibitor talazoparib.

Glucose induces protein targeting to glycogen in hepatocytes by fructose 2,6-bisphosphate-mediated recruitment of MondoA to the promoter.

In the liver, a high glucose concentration activates transcription of genes encoding glucose 6-phosphatase and enzymes for glycolysis and lipogenesis by elevation in phosphorylated intermediates and recruitment of the transcription factor ChREBP (carbohydrate response element binding protein) and its partner, Mlx, to gene promoters. A proposed function for this mechanism is intracellular phosphate homeostasis. In extrahepatic tissues, MondoA, the paralog of ChREBP, partners with Mlx in transcriptional induction by glucose. We tested for glucose induction of regulatory proteins of the glycogenic pathway in hepatocytes and identified the glycogen-targeting proteins, G(L) and PTG (protein targeting to glycogen), as being encoded by Mlx-dependent glucose-inducible genes. PTG induction by glucose was MondoA dependent but ChREBP independent and was enhanced by forced elevation of fructose 2,6-bisphosphate and by additional xylitol-derived metabolites. It was counteracted by selective depletion of fructose 2,6-bisphosphate with a bisphosphatase-active kinase-deficient variant of phosphofructokinase 2/fructosebisphosphatase 2, which prevented translocation of MondoA to the nucleus and recruitment to the PTG promoter. We identify a novel role for MondoA in the liver and demonstrate that elevated fructose 2,6-bisphosphate is essential for recruitment of MondoA to the PTG promoter. Phosphometabolite activation of MondoA and ChREBP and their recruitment to target genes is consistent with a mechanism for gene regulation to maintain intracellular phosphate homeostasis.

A novel mechanism for regulating hepatic glycogen synthesis involving serotonin and cyclin-dependent kinase-5.

Hepatic autonomic nerves regulate postprandial hepatic glucose uptake, but the signaling pathways remain unknown. We tested the hypothesis that serotonin (5-hydroxytryptamine [5-HT]) exerts stimulatory and inhibitory effects on hepatic glucose disposal. Ligands of diverse 5-HT receptors were used to identify signaling pathway(s) regulating glucose metabolism in hepatocytes. 5-HT had stimulatory and inhibitory effects on glycogen synthesis in hepatocytes mediated by 5-HT1/2A and 5-HT2B receptors, respectively. Agonists of 5-HT1/2A receptors lowered blood glucose and increased hepatic glycogen after oral glucose loading and also stimulated glycogen synthesis in freshly isolated hepatocytes with greater efficacy than 5-HT. This effect was blocked by olanzapine, an antagonist of 5-HT1/2A receptors. It was mediated by activation of phosphorylase phosphatase, inactivation of glycogen phosphorylase, and activation of glycogen synthase. Unlike insulin action, it was not associated with stimulation of glycolysis and was counteracted by cyclin-dependent kinase (cdk) inhibitors. A role for cdk5 was supported by adaptive changes in the coactivator protein p35 and by elevated glycogen synthesis during overexpression of p35/cdk5. These results support a novel mechanism for serotonin stimulation of hepatic glycogenesis involving cdk5. The opposing effects of serotonin, mediated by distinct 5-HT receptors, could explain why drugs targeting serotonin function can cause either diabetes or hypoglycemia in humans.

Invariant natural killer T (iNKT) cell deficiency in chronic mucocutaneous candidiasis--a consequence or a cause?

Chronic mucocutaneous candidiasis (CMC) is a group of heterogeneous disorders characterised by primary selective susceptibility to chronic, recurrent Candida infections. The genetic defect of one subgroup of CMC patients have been identified as mutations of the autoimmune regulator (AIRE) gene. Recent data implicated the AIRE gene in iNKT cell development, raising the possibility that iNKT cells may be important in defending against Candida infections. In this study, we enumerated the circulating iNKT frequency in 22 CMC patients (9 with AIRE gene mutations) and 25 healthy controls. We also examined the effect of Candida stimulation on iNKT cells in vitro. Our data demonstrated that peripheral iNKT cell frequency is significantly reduced in CMC patients compared to healthy controls, regardless of their AIRE gene mutation status. Direct stimulation with heat-inactivated whole Candida did not induce iNKT cell proliferation. Furthermore, circulating iNKT cell frequencies in some healthy controls were comparable to CMC patients. These observations suggest that iNKT cell deficiency is part of the CMC disease phenotype irrespective of the presence of AIRE gene mutations but does not appear to confer susceptibility to chronic Candida infections. We postulate that the reduced circulating iNKT cell frequency in CMC is a consequence rather than a cause of chronic Candida infections.

Elevated glucose represses liver glucokinase and induces its regulatory protein to safeguard hepatic phosphate homeostasis.

OBJECTIVE: The induction of hepatic glucose 6-phosphatase (G6pc) by glucose presents a paradox of glucose-induced glucose intolerance. We tested whether glucose regulation of liver gene expression is geared toward intracellular homeostasis. RESEARCH DESIGN AND METHODS: The effect of glucose-induced accumulation of phosphorylated intermediates on expression of glucokinase (Gck) and its regulator Gckr was determined in hepatocytes. Cell ATP and uric acid production were measured as indices of cell phosphate homeostasis. RESULTS: Accumulation of phosphorylated intermediates in hepatocytes incubated at elevated glucose induced rapid and inverse changes in Gck (repression) and Gckr (induction) mRNA concomitantly with induction of G6pc, but had slower effects on the Gckr-to-Gck protein ratio. Dynamic metabolic labeling in mice and liver proteome analysis confirmed that Gckr and Gck are low-turnover proteins. Involvement of Max-like protein X in glucose-mediated Gck-repression was confirmed by chromatin immunoprecipitation analysis. Elevation of the Gck-to-Gckr ratio in hepatocytes was associated with glucose-dependent ATP depletion and elevated urate production confirming compromised phosphate homeostasis. CONCLUSIONS: The lowering by glucose of the Gck-to-Gckr ratio provides a potential explanation for the impaired hepatic glucose uptake in diabetes. Elevated uric acid production at an elevated Gck-to-Gckr ratio supports a role for glucose regulation of gene expression in hepatic phosphate homeostasis.

The role of IkappaB kinase 2, but not activation of NF-kappaB, in the release of CXCR3 ligands from IFN-gamma-stimulated human bronchial epithelial cells.

The severity of chronic obstructive pulmonary disease correlates with increased numbers of cytotoxic CD8(+) T lymphocytes in the lung parenchyma. CD8(+) T lymphocytes release IFN-gamma which stimulates airway epithelial cells to produce CXCR3 chemokines leading to further recruitment of CD8(+) T lymphocytes. To evaluate the signaling pathways involved in regulation of CXCR3 ligands, the human bronchial epithelial cell line BEAS-2B was stimulated with IFN-gamma and the release of the CXCR3 ligands was measured by ELISA. The release of CXCL9, CXCL10, and CXCL11 was inhibited by an IkappaB kinase 2 (IKK2) selective inhibitor 2-[(Aminocarbonyl)amino]-5-[4-fluorophenyl]-3-thiophenecarboxamide (TPCA-1) (EC(50) values were 0.50 +/- 0.03, 0.17 +/- 0.06, and 0.45 +/- 0.10 microM, respectively (n = 6)) and an IKK1/2 selective inhibitor 2-amino-6-(2'cyclopropylemethoxy-6'-hydroxy-phenyl)-4-piperidin-3-yl-pyridine-3-carbonitrile (EC(50) values 0.74 +/- 0.40, 0.27 +/- 0.06, and 0.88 +/- 0.29 microM, respectively (n = 6)). The glucocorticosteroid dexamethasone had no effect on CXCR3 ligand release. The release of CXCL10 was most sensitive to inhibition by IKK2 and a role for IKK2 in CXCL10 release was confirmed by overexpression of dominant-negative adenoviral constructs to IKK2 (68.2 +/- 8.3% n = 5), but not of IKK1. Neither phosphorylation of IkappaBalpha, translocation of p65 to the nucleus, or activation of a NF-kappaB-dependent reporter (Ad-NF-kappaB-luc) were detected following stimulation of BEAS-2B cells with IFN-gamma. These data suggest that IKK2 is also involved in the IFN-gamma-stimulated release of the CXCR3 ligands through a novel mechanism that is independent NF-kappaB.