Hepatic iodothyronine deiodinase type 1 activity is decreased in two DeltaF508 cystic fibrosis mouse models.

BACKGROUND: Abnormal thyroid status has been reported in cystic fibrosis (CF) patients, and this can possibly be correlated to neuromuscular symptoms. Iodothyronine deiodinase type 1 (D1) activity is an important determinant of thyroid status, and we chose to investigate D1 activity in CF liver. METHODS: We have measured hepatic D1 activities in two DeltaF508 CF mouse models. RESULTS: Hepatic D1 activity was significantly reduced by 31% to 48% in homozygous DeltaF508 mice compared with wild-type genotypes. CONCLUSIONS: A decreased hepatic D1 activity could be the biochemical basis of some of the abnormal thyroid parameters observed in cystic fibrosis patients.     

CF gene and cystic fibrosis transmembrane conductance regulator expression in autosomal dominant polycystic kidney disease

Disease-modifying genes might participate in the significant intrafamilial variability of the renal phenotype in autosomal dominant polycystic kidney disease (ADPKD). Cystic fibrosis (CF) transmembrane conductance regulator (CFTR) is a chloride channel that promotes intracystic fluid secretion, and thus cyst progression, in ADPKD. The hypothesis that mutations of the CF gene, which encodes CFTR, might be associated with a milder renal phenotype in ADPKD was tested. A series of 117 unrelated ADPKD probands and 136 unaffected control subjects were screened for the 12 most common mutations and the frequency of the alleles of the intron 8 polymorphic TN: locus of CF. The prevalence of CF mutations was not significantly different in the ADPKD (1.7%, n = 2) and control (3.7%, n = 5) groups. The CF mutation was DeltaF508 in all cases, except for one control subject (1717-1G A). The frequencies of the 5T, 7T, and 9T intron 8 alleles were also similar in the ADPKD and control groups. Two additional patients with ADPKD and the DeltaF508 mutation were detected in the families of the two probands with CF mutations. Kidney volumes and renal function levels were similar for these four patients with ADPKD and DeltaF508 CFTR (heterozygous for three and homozygous for one) and for control patients with ADPKD collected in the University of Colorado Health Sciences Center database. The absence of a renal protective effect of the homozygous DeltaF508 mutation might be related to the lack of a renal phenotype in CF and the variable, tissue-specific expression of DeltaF508 CFTR. Immunohistochemical analysis of a kidney from the patient with ADPKD who was homozygous for the DeltaF508 mutation substantiated that hypothesis, because CFTR expression was detected in 75% of cysts (compared with <50% in control ADPKD kidneys) and at least partly in the apical membrane area of cyst-lining cells. These data do not exclude a potential protective role of some CFTR mutations in ADPKD but suggest that it might be related to the nature of the mutation and renal expression of the mutated CFTR.     

Autosomal dominant polycystic kidney disease coexisting with cystic fibrosis

Autosomal dominant polycystic kidney disease (ADPKD) is a common, inherited disorder characterized by the progressive enlargement of fluid-filled cysts in the kidneys and liver. Since the cystic fibrosis transmembrane conductance regulator (CFTR) Cl--channel may mediate the secretion of Cl--and fluid into the cysts, it is conceivable that coexisting cystic fibrosis (CF) in patients with ADPKD could attenuate their development. We previously reported that two patients with ADPKD coexisting with cystic fibrosis (CF) had a milder cystic phenotype than that of kindred without CFTR mutations. A subsequent report failed to confirm this protective effect. We now have identified another family with coexisting type 1 ADPKD and CF. The kidney volumes and the number and size of renal and hepatic cysts were markedly less in a member of this family with ADPKD (PKD1 mutation C508R) and CF (homozygous DeltaF508 mutation) than in her sister with ADPKD alone at comparable ages.     

Lumacaftor-ivacaftor effects on cystic fibrosis-related liver involvement in adolescents with homozygous F508 del-CFTR

BackgroundThe effects of lumacaftor-ivacaftor on cystic fibrosis transmembrane conductance regulator (CFTR)-associated liver disease remain unclear. The objective of the study was to describe the effect of this treatment on features of liver involvement in a cystic fibrosis (CF) adolescent population homozygous for F508del.MethodsClinical characteristics, liver blood tests, abdominal ultrasonography (US), and pancreas and liver proton density fat fraction (PDFF) by magnetic resonance imaging, were obtained at treatment initiation and at 12 months for all patients. Biomarkers of CFTR activity (sweat chloride test, nasal potential difference, and intestinal current measurement) were assessed at initiation and at 6 months therapy.ResultsOf the 37 patients who started ivacaftor/lumacaftor treatment, 28 were eligible for analysis. In this group, before treatment initiation, 4 patients were diagnosed with multinodular liver and portal hypertension, 19 with other forms of CF liver involvement, and 5 with no signs of liver involvement. During treatment, no hepatic adverse reactions were documented, and no patient developed liver failure. Serum levels of alanine aminotransferase (ALT), aspartate aminotransferase (AST) and gammaglutamyl transferase (GGT) decreased significantly following initiation of lumacaftor-ivacaftor, and remained so after 12 months treatment. This was not correlated with changes in clinical status, liver and pancreas US and PDFF, fecal elastase, or lumacaftor-ivacaftor serum levels. The most “responsive” patients demonstrated a significant increase in biomarkers of CFTR activity.ConclusionsThese results may suggest a potential beneficial effect of CFTR modulators on CF liver disease and warrant further investigation in larger, prospective studies.     

Bax ablation protects against hepatic ischemia/reperfusion injury in transgenic mice.

Apoptosis appears to be a central mechanism of cell death following reperfusion of the ischemic liver. The aim of this study was to determine the effect of decreased expression of the proapoptotic Bax gene on hepatic apoptotic warm ischemia/reperfusion (I/R) injury. Three groups of mice were studied: homozygotic knockout mice (Bax-/-); heterozygotic (Bax+/-); and wild type (Bax+/+). Isolated mouse livers were subjected to 90 minutes of ischemia (37 degrees C) followed by 15 minutes of reperfusion. Bax and Bcl-2 expression in liver tissue homogenates was measured by Western blot. Serum liver enzyme levels were measured and intrahepatic caspase-3 activity was determined by fluorimetric assay. Oil red O (ORO) staining was performed for fat detection. Apoptotic cells were identified by morphological criteria, immunohistochemistry for caspase-3, and terminal deoxynucleotidyl transferase-mediated 2'-deoxyuridine 5'-triphosphate nick-end labeling (TUNEL) assay. At 1 minute of reperfusion, the ischemic (Bax-/-) livers were characterized by statistically significantly lower liver enzyme levels and lower caspase-3 activity than the ischemic (Bax+/+) livers (P<0.05 for both). The reduction in postischemic apoptotic hepatic injury in the ischemic Bax-/- livers group was confirmed morphologically, by the significantly reduced microvesicular steatosis as determined by ORO staining, fewer apoptotic hepatocyte cells detected (P<0.05); immunohistochemically, by the significantly weaker activation of caspase-3 compared to the ischemic group (P<0.05); and by TUNEL assay (P<0.05). Similar levels of antiapoptotic Bcl-2 protein expression were detected in all 3 groups of ischemic livers on Western blots. Bax protein was not expressed in Bax-deficient livers and was detected in Bax+/+ normal livers. In the Bax+/- livers, levels of the damage markers were moderate. In conclusion, The better tolerance of Bax knockout livers to I/R injury suggests that the Bax gene may serve as a potential target for therapeutic intervention in hepatic I/R injury.     

Sildenafil (Viagra) corrects DeltaF508-CFTR location in nasal epithelial cells from patients with cystic fibrosis

BACKGROUND: Most patients with cystic fibrosis (CF) have a DeltaF508 mutation resulting in abnormal retention of mutant gene protein (DeltaF508-CFTR) within the cell. This study was undertaken to investigate DeltaF508-CFTR trafficking in native cells from patients with CF with the aim of discovering pharmacological agents that can move DeltaF508-CFTR to its correct location in the apical cell membrane. METHOD: Nasal epithelial cells were obtained by brushing from individuals with CF. CFTR location was determined using immunofluorescence and confocal imaging in untreated cells and cells treated with sildenafil. The effect of sildenafil treatment on CFTR chloride transport function was measured in CF15 cells using an iodide efflux assay. RESULTS: In most untreated CF cells DeltaF508-CFTR was mislocalised within the cell at a site close to the nucleus. Exposure of cells to sildenafil (2 hours at 37 degrees C) resulted in recruitment of DeltaF508-CFTR to the apical membrane and the appearance of chloride transport activity. Sildenafil also increased DeltaF508-CFTR trafficking in cells from individuals with CF with a single copy DeltaF508 (DeltaF508/4016ins) or with a newly described CF trafficking mutation (R1283M). CONCLUSIONS: The findings provide proof of principle for sildenafil as a DeltaF508-CFTR trafficking drug and give encouragement for future testing of sildenafil and related PDE5 inhibitors in patients with CF.     

Expression of the inflammatory regulator A20 correlates with lung function in patients with cystic fibrosis

BackgroundA20 and TAX1BP1 interact to negatively regulate NF-κB-driven inflammation. A20 expression is altered in F508del/F508del patients. Here we explore the effect of CFTR and CFTR genotype on A20 and TAX1BP1 expression. The relationship with lung function is also assessed.MethodsPrimary nasal epithelial cells (NECs) from CF patients (F508del/F508del, n = 7, R117H/F508del, n = 6) and controls (age-matched, n = 8), and 16HBE14o- cells were investigated. A20 and TAX1BP1 gene expression was determined by qPCR.ResultsSilencing of CFTR reduced basal A20 expression. Following LPS stimulation A20 and TAX1BP1 expression was induced in control NECs and reduced in CF NECs, broadly reflecting the CF genotype: F508del/F508del had lower expression than R117H/F508del. A20, but not TAX1BP1 expression, was proportional to FEV₁ in all CF patients (r = 0.968, p < 0.001).ConclusionsA20 expression is reduced in CF and is proportional to FEV₁. Pending confirmation in a larger study, A20 may prove a novel predictor of CF inflammation/disease severity.     

Abrogating Monoacylglycerol Acyltransferase Activity in Liver Improves Glucose Tolerance and Hepatic Insulin Signaling in Obese Mice

Monoacylglycerol acyltransferase (MGAT) enzymes convert monoacylglycerol to diacylglycerol (DAG), a lipid that has been linked to the development of hepatic insulin resistance through activation of protein kinase C (PKC). The expression of genes that encode MGAT enzymes is induced in the livers of insulin-resistant human subjects with nonalcoholic fatty liver disease, but whether MGAT activation is causal of hepatic steatosis or insulin resistance is unknown. We show that the expression of Mogat1, which encodes MGAT1, and MGAT activity are also increased in diet-induced obese (DIO) and ob/obmice. To probe the metabolic effects of MGAT1 in the livers of obese mice, we administered antisense oligonucleotides (ASOs) against Mogat1 to DIO and ob/ob mice for 3 weeks. Knockdown of Mogat1 in liver, which reduced hepatic MGAT activity, did not affect hepatic triacylglycerol content and unexpectedly increased total DAG content. Mogat1 inhibition also increased both membrane and cytosolic compartment DAG levels. However, Mogat1 ASO treatment significantly improved glucose tolerance and hepatic insulin signaling in obese mice. In summary, inactivation of hepatic MGAT activity, which is markedly increased in obese mice, improved glucose tolerance and hepatic insulin signaling independent of changes in body weight, intrahepatic DAG and TAG content, and PKC signaling.     

Lumacaftor/ivacaftor improves liver cholesterol metabolism but does not influence hypocholesterolemia in patients with cystic fibrosis

BackgroundCystic fibrosis (CF) patients have reduced intestinal absorption of sterols and, despite enhanced endogenous synthesis, low plasma cholesterol. Lumacaftor/ivacaftor CFTR protein modulator therapy is used to improve the clinical outcome of CF patients homozygous for F508del mutation (homo-deltaF508). Aim of the study is to evaluate the cholesterol metabolism and hepatobiliary injury/function in adult homo-deltaF508 patients, before and after lumacaftor/ivacaftor treatment. Baseline parameters in homo-deltaF508 patients were compared to those in CF patients compound heterozygous for F508del mutation and another severe mutation (hetero-deltaF508).MethodsCholesterol metabolism was evaluated measuring plasma phytosterols and cholestanol, as intestinal absorption markers, and lathosterol, as liver biosynthesis marker. We quantified serum vitamin E, as nutritional marker. We evaluated liver injury by aspartate aminotransferase (AST) and alanine transaminase (ALT), biliary injury by γ-glutamyltransferase (γGT) and AP, and the liver function by bilirubin and albumin.ResultsBefore the treatment, homo-deltaF508 patients (n = 20) had significantly lower cholesterol and vitamin E compared to hetero-deltaF508 (n = 20). Lumacaftor/ivacaftor treatment caused: 1) further reduction of cholesterol; 2) lathosterol reduction, suggesting a normalization of endogenous synthesis; 3) cholestanol and vitamin E increment, indicating an improvement of lipid digestion/absorption. Vitamin E difference (after-before treatment) was positively associated to treatment months. Alkaline phosphatase was also reduced.ConclusionsThese data suggest an effect of lumacaftor/ivacaftor on cholesterol metabolism and enterohepatic flux in CF patients. However, lumacaftor/ivacaftor does not promote the increase of cholesterol serum concentration that on the contrary declines. Further studies are needed to research the real mechanism causing this reduction.     

High incidence of the CFTR mutations 3272-26A → G and L927P in Belgian cystic fibrosis patients, and identification of three new CFTR mutations (186-2A → G, E588V, and 1671insTATCA)

We have analyzed 143 unrelated Belgian patients with a positive diagnosis of cystic fibrosis (CF) for mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene. An initial screening for 29 CFTR mutations led to mutation identification in 89.9% of the tested chromosomes. Subsequently an extensive analysis of the CFTR gene was performed by denaturating gradient gel electrophoresis (DGGE) in those patients with at least one unknown mutation after preliminary screening. In addition to 10 previously reported mutations we identified 2 new mutations 186-2A-->G and E588V. A third new mutation 1671insTATCA was identified during routine screening for DeltaF508. Two mutations were detected with a higher frequency than expected: 3272-26A-->G, which is the second most common mutation after DeltaF508 in our CF population with a frequency of 3.8%, and L927P (2.4%). The clinical data is presented for the mutations 186-2A-->G, E588V, 3272-26A-->G and L927P. The mutation data are useful for the Belgian population to supplement the initial screening set of mutations.     

Inhibition of SULT2B1b expression alters effects of 3beta-hydroxysteroids on cell proliferation and steroid hormone receptor expression in human LNCaP prostate cancer cells

BACKGROUND: Sulfation is an important steroid inactivation in human tissues. Sulfotransferase (SULT) 2B1b selectively conjugates 3beta-hydroxysteroids and is expressed in epithelial cells of normal and cancerous prostate tissues. Dehydroepiandrosterone (DHEA) and Delta(5)-androstenediol (Delta(5)-Adiol) sulfation prevents their conversion to more potent androgens and estrogens in tissues although both compounds may also be biologically active. METHODS: SULT2B1b expression and activity were inhibited >85% in human LNCaP prostate adenocarcinoma cells using short interference RNA (siRNA). The effects of treating control and SULT2B1b-deficient LNCaP cells with DHEA, Delta(5)-Adiol, and 5alpha-androstane-3beta-17beta-diol (Anstane-diol) on cellular proliferation, estrogen receptors (ERs), androgen receptor (AR), and prostate specific antigen protein levels were examined. RESULTS: Physiological concentrations of DHEA and Delta(5)-Adiol increased proliferation of control cells and the proliferative effects were significantly increased in SULT2B1b-siRNA cells. DHEA, but not Delta(5)-Adiol increased AR levels at concentrations >/=1,000 nM in SULT2B1b-siRNA cells but not in control LNCaP cells. ER-alpha levels were not affected with any of the compounds tested. Physiological concentrations of DHEA and Delta(5)-A-diol decreased ER-beta levels in control cells and had significantly greater effects in SULT2B1b-siRNA cells. In contrast, Anstane-diol had no effect on AR or ER-alpha levels but induced more elevation of ER-beta levels in SULT2B1b-siRNA cells at concentrations >/=1,000 nM. CONCLUSIONS: SULT2B1b is involved in regulating prostate cell responsiveness to DHEA and Delta(5)-Adiol. Inhibition of SULT2B1b increased cell proliferation and ER-beta repression after treatment with physiological levels of DHEA and Delta(5)-Adiol indicating that SULT2B1b has an inhibitory effect on DHEA and Delta(5)-Adiol activity.     

Genotype–phenotype relationship for five CFTR mutations frequently identified in western France

BACKGROUND: Cystic fibrosis (CF) is the most common inherited disorder in Caucasian populations, with more than 1000 cystic fibrosis transmembrane conductance regulator (CFTR) mutations presently described. The distribution of the mutations ranges widely between countries and/or ethnic groups. Multicentric studies are usually needed to study the genotype-phenotype correlations. METHODS: Since 1992, the French CF Registry (FCFR) has collected and analyzed data from most of the CF patients regularly seen in CF care centres in France. We compared the mutation distribution of the patients born in western France to that of those born elsewhere in France. Then we extracted the available data for all the compound heterozygotes carrying the DeltaF508 allele and one of the following mutations: DeltaI507, 1078delT, 4005+1G->A, E60X and W846X, and matched a patient homozygous for the DeltaF508 mutation for each of them. RESULTS: Western France appeared to have a specific distribution of some CF mutations. Furthermore, disparities were found regarding the mutation repartition (DeltaI507 in Normandy, 1078delT, 4005+1G->A and W846X in western Brittany). Genotype-phenotype correlations showed a wide heterogeneity. Although variations were found, DeltaI507/DeltaF508, 4005+1G->A/DeltaF508 and 1078delT/DeltaF508 patients appeared to have a similar disease as the DeltaF508/DeltaF508 patients. Although the W846X and E60X mutations should be considered as severe alleles as regards to pancreatic function, they were associated with less severe pulmonary manifestations and, probably, better prognosis. CONCLUSION: The knowledge of the distribution of uncommon CF mutations specific to particular areas and of their associated phenotype makes up an essential tool in the management of local CF patients.     

Vitamin E Succinate Enhances Steatotic Liver Energy Status and Prevents Oxidative Damage Following Ischemia/Reperfusion

We have previously shown that treatment of steatotic livers with vitamin E succinate decreases liver injury and increases survival after ischemia/reperfusion (I/R). It is now understood that compromised energy status is associated with increased injury following liver ischemia in the setting of hepatic steatosis at least partially as a result of increased reactive oxygen species (ROS) and induction of mitochondrial uncoupling protein-2 (UCP2). Given the association between ROS, mitochondrial function, and UCP2, it was our goal to determine whether the protective effects of vitamin E succinate were associated with decreased ROS injury, down-regulation of UCP2, or improvement of ATP levels following I/R. To test this, leptin deficient (ob/ob) mice with steatotic livers that had received other 50 IU of vitamin E succinate supplement per day or control chow for 7 days were subjected to total hepatic ischemia (15 minutes) followed by reperfusion. We measured liver expressions of ATP, glutathione (GSH), and UCP2 as well as mitochondrial DNA damage. Vitamin E treatment decreased hepatic UCP2 expression and increased ATP and GSH levels prior to I/R. These levels were maintained at 1 hour after I/R. At 24 hours, while hepatic UCP2 expression, ATP, and GSH levels were similar to those of mice not receiving vitamin E, mitochondrial DNA damage was blocked. These results revealed that vitamin E succinate decreased hepatic UCP2 expression, reduced oxidative stress, and improved mitochondrial function in mice with steatotic livers before and after I/R, identifying mechanisms of protection in this setting.     

Depletion of BAFF cytokine exacerbates infection in Pseudomonas aeruginosa infected mice

BackgroundCystic fibrosis (CF) is a genetic disease characterized by chronic inflammation of the lungs that is ineffective at clearing pathogens. B-cell activating factor (BAFF), a cytokine involved in the development of B-cells, is known to be elevated in CF patients with subclinical infections. We postulate that the elevated BAFF levels in CF patients might be triggered by Pseudomonas aeruginosa infection and it might play a protective role in the regulation of lung responses to infection.MethodsTo address this hypothesis, we used a well characterized model of CFTR.KO mice infected with a clinical strain of P. aeruginosa (PA508). We quantified cell types with flow cytometry, concentration of cytokines by ELISA tests, bacterial load by colony counting and lung physiology by metacholine-induced lung resistance.ResultsOur data demonstrates that BAFF is not elevated in uninfected CF mice, and infection with Pseudomonas leads to significant induction of this regulatory cytokine. We also demonstrate that the maintenance of BAFF levels and its induction during the infection is important for clearance of Pseudomonas infection as its depletion during the course of infection leads to decrease in the resolution of infection both in WT and CFTR-KO mice. Interestingly, the depletion of BAFF not only results in a depletion of B cells numbers but also to a significant decrease in the number of regulatory T cells in the non-infected lungs.ConclusionsOverall, our data demonstrate for the first time that BAFF is an important regulatory molecule helping to maintain the immunological response to infection and clearance of lung infection.     

Severity of the S1251N allele in cystic fibrosis is affected by the presence of the F508C variant in cis

BackgroundIn cystic fibrosis (CF), genotype-phenotype correlation is complicated by the large number of CFTR variants, the influence of modifier genes, environmental effects, and the existence of complex alleles. We document the importance of complex alleles, in particular the F508C variant present in cis with the S1251N disease-causing variant, by detailed analysis of a patient with CF, with the [S1251N;F508]/G542X genotype and a very mild phenotype, contrasting it to that of four subjects with the [S1251N;F508C]/F508del genotype and classical CF presentation.MethodsGenetic differences were identified by Sanger sequencing and CFTR function was quantified using rectal organoids in rectal organoid morphology analysis (ROMA) and forskolin-induced swelling (FIS) assays. CFTR variants were further characterised in CF bronchial epithelial (CFBE) cell lines. The impact of involved amino acid changes in the CFTR 3D protein structure was evaluated.ResultsOrganoids of the patient [S1251N;F508] with mild CF phenotype confirmed the CF diagnosis but showed higher residual CFTR function compared to the four others [S1251N;F508C]. CFBE cell lines showed a decrease in [S1251N;F508C]-CFTR function but not in processing when compared to [S1251N;F508]-CFTR. Analysis of the 3D CFTR structure suggested an additive deleterious effect of the combined presence of S1251N and F508C with respect to NBD1-2 dimerisation.ConclusionsIn vitro and in silico data show that the presence of F508C in cis with S1251N decreases CFTR function without affecting processing. Complex CFTR alleles play a role in clinical phenotype and their identification is relevant in the context of personalised medicine for each patient with CF.     

活体生物荧光成像技术检测HO-1在HO-1/Luc小鼠肝脏缺血模型中的表达

目的尝试使用活体生物荧光成像技术无创定量检测HO-1在活体动物肝脏温缺血模型中的时空表达。方法建立小鼠部分肝脏温缺血模型，使用活体生物荧光成像技术连续检测HO-1在HO-1／Luc转基因报告小鼠中的转录情况。使用RT-PCR方法检测HO-1 mRNA水平，免疫组织化学方法行HO-1的表达定位。结果缺血肝叶发出的荧光信号最早于再灌注后3h被检测到，随后信号不断增强在9h达到峰值，然后信号逐渐减弱至再灌注后48h恢复至基础水平。RT-PCR方法测得在HO-1蛋白上调之前出现了HO-1mRNA的表达增强。免疫组织化学染色方法证实肝脏细胞是缺血再灌注损伤后HO-1表达上调的主要部位。结论活体生物荧光成像技术可以实时定量检测肝脏缺血后HO-1的表达，是一项敏感的检测技术。     

Renal effects of glibenclamide in cystic fibrosis mice.

In vitro studies have shown that glibenclamide sensitivity is conferred upon Kir 1.1 K(+) channels when they are co-expressed with the cystic fibrosis transmembrane conductance regulator (CFTR). In rats, glibenclamide acts as a K(+)-sparing diuretic by a mechanism that involves blockade of Kir 1.1 channels in the distal nephron. To test whether interaction between Kir 1.1 and CFTR is required to mediate the renal effects of glibenclamide (15 mg/kg), clearance experiments were performed comparing wild type (WT) and Cftr(tm2cam) Delta F508 cystic fibrosis (CF) mice. Glibenclamide treatment was associated with an equivalent diuresis in both WT and CF mice. Glibenclamide was K(+)-sparing in both genotypes with no significant change in urinary K(+) excretion observed. That glibenclamide was an effective K(+)-sparing diuretic in CF animals suggests that CFTR expression is not a requirement to mediate its renal actions in mice.