Obesity and its associated metabolic syndromes represent a growing global challenge, yet mechanistic understanding of this pathology and current therapeutics are unsatisfactory. We discovered that ...CD4(+) T lymphocytes, resident in visceral adipose tissue (VAT), control insulin resistance in mice with diet-induced obesity (DIO). Analyses of human tissue suggest that a similar process may also occur in humans. DIO VAT-associated T cells show severely biased T cell receptor V(alpha) repertoires, suggesting antigen-specific expansion. CD4(+) T lymphocyte control of glucose homeostasis is compromised in DIO progression, when VAT accumulates pathogenic interferon-gamma (IFN-gamma)-secreting T helper type 1 (T(H)1) cells, overwhelming static numbers of T(H)2 (CD4(+)GATA-binding protein-3 (GATA-3)(+)) and regulatory forkhead box P3 (Foxp3)(+) T cells. CD4(+) (but not CD8(+)) T cell transfer into lymphocyte-free Rag1-null DIO mice reversed weight gain and insulin resistance, predominantly through T(H)2 cells. In obese WT and ob/ob (leptin-deficient) mice, brief treatment with CD3-specific antibody or its F(ab')(2) fragment, reduces the predominance of T(H)1 cells over Foxp3(+) cells, reversing insulin resistance for months, despite continuation of a high-fat diet. Our data suggest that the progression of obesity-associated metabolic abnormalities is under the pathophysiological control of CD4(+) T cells. The eventual failure of this control, with expanding adiposity and pathogenic VAT T cells, can successfully be reversed by immunotherapy.
Allelic heterogeneity in disease-causing genes presents a substantial challenge to the translation of genomic variation into clinical practice. Few of the almost 2,000 variants in the cystic fibrosis ...transmembrane conductance regulator gene CFTR have empirical evidence that they cause cystic fibrosis. To address this gap, we collected both genotype and phenotype data for 39,696 individuals with cystic fibrosis in registries and clinics in North America and Europe. In these individuals, 159 CFTR variants had an allele frequency of ł0.01%. These variants were evaluated for both clinical severity and functional consequence, with 127 (80%) meeting both clinical and functional criteria consistent with disease. Assessment of disease penetrance in 2,188 fathers of individuals with cystic fibrosis enabled assignment of 12 of the remaining 32 variants as neutral, whereas the other 20 variants remained of indeterminate effect. This study illustrates that sourcing data directly from well-phenotyped subjects can address the gap in our ability to interpret clinically relevant genomic variation.
Genetic modifiers of lung disease in cystic fibrosis Drumm, Mitchell L; Konstan, Michael W; Schluchter, Mark D ...
New England journal of medicine/The New England journal of medicine,
10/2005, Letnik:
353, Številka:
14
Journal Article
Recenzirano
Odprti dostop
Polymorphisms in genes other than the cystic fibrosis transmembrane conductance regulator (CFTR) gene may modify the severity of pulmonary disease in patients with cystic fibrosis.
We performed two ...studies with different patient samples. We first tested 808 patients who were homozygous for the DeltaF508 mutation and were classified as having either severe or mild lung disease, as defined by the lowest or highest quartile of forced expiratory volume in one second (FEV1), respectively, for age. We genotyped 16 polymorphisms in 10 genes reported by others as modifiers of disease severity in cystic fibrosis and tested for an association in patients with severe disease (263 patients) or mild disease (545). In the replication (second) study, we tested 498 patients, with various CFTR genotypes and a range of FEV1 values, for an association of the TGFbeta1 codon 10 CC genotype with low FEV1.
In the initial study, significant allelic and genotypic associations with phenotype were seen only for TGFbeta1 (the gene encoding transforming growth factor beta1), particularly the -509 and codon 10 polymorphisms (with P values obtained with the use of Fisher's exact test and logistic regression ranging from 0.006 to 0.0002). The odds ratio was about 2.2 for the highest-risk TGFbeta1 genotype (codon 10 CC) in association with the phenotype for severe lung disease. The replication study confirmed the association of the TGFbeta1 codon 10 CC genotype with more severe lung disease in comparisons with the use of dichotomized FEV1 for severity status (P=0.0002) and FEV1 values directly (P=0.02).
Genetic variation in the 5' end of TGFbeta1 or a nearby upstream region modifies disease severity in cystic fibrosis.
Cigarette smoke extract inhibits chloride secretion in human bronchial epithelial cells. Oxidants decrease gene expression, protein expression, and function of the cystic fibrosis transmembrane ...conductance regulator (CFTR).
Because cigarette smoke is a rich source of oxidants, we verified the hypothesis that CFTR may be suppressed by exposure to cigarette smoke in vitro and in vivo.
The effects of cigarette smoke exposure on Calu-3 and T84 cell CFTR expression and function were observed. Also studied were the nasal potential differences (PDs) in 26 men (9 smokers, 17 nonsmokers) who had no detectable CFTR gene mutations as determined during investigations for infertility. CFTR expression and function were determined by Northern blotting, Western blotting, and cAMP-dependent 125I efflux assays. Extensive CFTR genotyping was performed in each subject. Nasal PD measurements were made at baseline and during amiloride, chloride-free buffer, and isoproterenol perfusions.
Cigarette smoke decreased CFTR expression and function in Calu-3 and T84 cell lines. Furthermore, the nasal PDs of cigarette smokers showed a pattern typical of CFTR deficiency with a blunted response to chloride-free buffer and isoproterenol compared with nonsmokers (-9.6 +/- 4.0 vs. -22.3 +/- 10.1 mV; p < 0.001).
We conclude that cigarette smoke decreases the expression of CFTR gene, protein, and function in vitro and that acquired CFTR deficiency occurs in the nasal respiratory epithelium of cigarette smokers. We suggest that acquired CFTR deficiency may contribute to the physiopathology of cigarette-induced diseases such as chronic bronchitis.
To identify human intronic sequences associated with 5' splice site recognition, we performed a systematic search for motifs enriched in introns downstream of both constitutive and alternative ...cassette exons. Significant enrichment was observed for U-rich motifs within 100 nucleotides downstream of 5' splice sites of both classes of exons, with the highest enrichment between positions +6 and +30. Exons adjacent to U-rich intronic motifs contain lower frequencies of exonic splicing enhancers and higher frequencies of exonic splicing silencers, compared with exons not followed by U-rich intronic motifs. These findings motivated us to explore the possibility of a widespread role for U-rich motifs in promoting exon inclusion. Since cytotoxic granule-associated RNA binding protein (TIA1) and TIA1-like 1 (TIAL1; also known as TIAR) were previously shown in vitro to bind to U-rich motifs downstream of 5' splice sites, and to facilitate 5' splice site recognition in vitro and in vivo, we investigated whether these factors function more generally in the regulation of splicing of exons followed by U-rich intronic motifs. Simultaneous knockdown of TIA1 and TIAL1 resulted in increased skipping of 36/41 (88%) of alternatively spliced exons associated with U-rich motifs, but did not affect 32/33 (97%) alternatively spliced exons that are not associated with U-rich motifs. The increase in exon skipping correlated with the proximity of the first U-rich motif and the overall "U-richness" of the adjacent intronic region. The majority of the alternative splicing events regulated by TIA1/TIAL1 are conserved in mouse, and the corresponding genes are associated with diverse cellular functions. Based on our results, we estimate that approximately 15% of alternative cassette exons are regulated by TIA1/TIAL1 via U-rich intronic elements.
To define the clinical characteristics and diagnostic parameters of patients with cystic fibrosis (CF) diagnosed in adulthood.
Retrospective cohort study.
Tertiary care center.
All patients with a ...diagnosis of CF made at the Toronto CF Clinics between 1960 and June 2001. Data were collected prospectively and analyzed retrospectively.
There were 73 of 1,051 patients (7%) with CF diagnosed in adulthood. Over time, an increasing number and proportion of patients received a diagnosis in adulthood: 27 patients (3%) before 1990, compared to 46 patients (18%) after 1990 (p < 0.001). The mean sweat chloride level was lower for those with CF diagnosed as adults, compared to those with a diagnosis as children (75 ± 26 mmol/L and 100 ± 19 mmol/L, respectively; p < 0.001) mean ± SD, and adults were more likely to have pancreatic sufficiency (PS) than children (73% vs 13%, respectively; p < 0.0001). In 46 adults who received a diagnosis since 1990, the reason for the initial sweat test was pancreatitis (2 patients, 4%), pulmonary symptoms (18 patients, 39%), pulmonary and GI symptoms (10 patients, 22%), infertility (12 patients, 26%), and genetic screening (4 patients, 9%). Other manifestations were biliary cirrhosis (one patient) and diabetes mellitus (four patients, 9%). The diagnosis could be confirmed by sweat test alone in 30 of 46 patients (65%), by mutation analysis alone in 15 patients (33%), and by a combination in 31 patients (67%). Nasal potential difference (PD) measurements alone confirmed the diagnosis in the remaining 15 patients (33%).
Patients with CF presenting in adulthood often have PS, inconclusive sweat test results, and a high prevalence of mutations that are not commonly seen in CF diagnosed in childhood. Although most patients have lung disease of variable degrees, single-organ manifestations such as congenital bilateral absence of the vas deferens and pancreatitis are seen. Repeated sweat tests and extensive mutation analysis are often required. Nasal PD may aid the diagnosis, but has not been standardized for clinical diagnosis.
Background Previous studies report a high frequency of mutations in the cystic fibrosis (CF) transmembrane conductance regulator gene (CFTR) in patients with idiopathic bronchiectasis. However, most ...studies have based their findings on preselected patient groups or have performed limited testing for CF transmembrane conductance regulator (CFTR) dysfunction. The objective of our study was to evaluate the prevalence of CFTR gene mutations and/or CFTR-related ion channel abnormalities among subjects with idiopathic chronic sinopulmonary disease and the prevalence of CF or a CFTR-related disorder in this population. Methods We evaluated 72 prospectively enrolled patients from 1995 to 2005 at the Hospital for Sick Children and St. Michael's Hospital with idiopathic chronic sinopulmonary disease for evidence of CFTR-mediated abnormalities. We performed CFTR genotyping and assessed CFTR function using sweat testing and nasal potential difference testing. The results were compared with data from healthy control subjects, CF heterozygotes, and patients with CF. Results The CFTR functional tests in idiopathic sinopulmonary patients showed a continuous spectrum, ranging from normal to values typically seen in individuals with CF. Forty-eight patients (66%) demonstrated CFTR mutations and/or abnormalities of CFTR function. Twenty-two (31%) fulfilled criteria for a diagnosis of CF and 26 (36%) for a CFTR-related disorder with a strong female preponderance. Functional tests, more than genotyping, were instrumental in establishing a CF diagnosis. Clinical features failed to distinguish subjects with CF from those with CFTR-related or idiopathic disease. Conclusions The high prevalence of CF and CFTR dysfunction among patients with idiopathic chronic sinopulmonary disease underscores the need for extensive diagnostic evaluation for CF.
Cystic fibrosis (CF) is caused by mutations in the CF transmembrane conductance regulator (CFTR) gene which encodes a protein expressed in the apical membrane of exocrine epithelial cells. CFTR ...functions principally as a cAMP-induced chloride channel and appears capable of regulating other ion channels. Besides the most common mutation, DeltaF508, accounting for about 70% of CF chromosomes worldwide, more than 850 mutant alleles have been reported to the CF Genetic Analysis Consortium. These mutations affect CFTR through a variety of molecular mechanisms which can produce little or no functional CFTR at the apical membrane. This genotypic variation provides a rationale for phenotypic effects of the specific mutations. The extent to which various CFTR alleles contribute to clinical variation in CF is evaluated by genotype-phenotype studies. These demonstrated that the degree of correlation between CFTR genotype and CF phenotype varies between its clinical components and is highest for the pancreatic status and lowest for pulmonary disease. The poor correlation between CFTR genotype and severity of lung disease strongly suggests an influence of environmental and secondary genetic factors (CF modifiers). Several candidate genes related to innate and adaptive immune response have been implicated as pulmonary CF modifiers. In addition, the presence of a genetic CF modifier for meconium ileus has been demonstrated on human chromosome 19q13.2. The phenotypic spectrum associated with mutations in the CFTR gene extends beyond the classically defined CF. Besides patients with atypical CF, there are large numbers of so-called monosymptomatic diseases such as various forms of obstructive azoospermia, idiopathic pancreatitis or disseminated bronchiectasis associated with CFTR mutations uncharacteristic for CF. The composition, frequency and type of CFTR mutations/variants parallel the spectrum of CFTR-associated phenotypes, from classic CF to mild monosymptomatic presentations. Expansion of the spectrum of disease associated with the CFTR mutant genes creates a need for revision of the diagnostic criteria for CF and a dilemma for setting nosologic boundaries between CF and other diseases with CFTR etiology.
Objective To determine whether primary sclerosing cholangitis (PSC) in childhood is associated with abnormalities in cystic fibrosis transmembrane conductance regulator (CFTR). Study design Subjects ...with PSC diagnosed in childhood (n = 20) were recruited from Children’s Hospital. Subjects had testing with sweat chloride concentration, nasal transmembrane potential difference, and extensive genetic analysis of the CFTR gene. Disease control subjects consisted of 14 patients with inflammatory bowel disease alone and no liver disease. t Tests were performed to determine statistical significance. Results In the PSC group, CFTR chloride channel function (ΔChloride free + isoproterenol) was markedly diminished at −8.6 ± 8.2 mV (reference range: −24.6 ± 10.4 mV). In contrast, disease control subjects had normal function, at −17.8 ± 9.7 mV ( P = .008). Sweat chloride concentration in subjects with PSC was greater than in disease control subjects (20.8 ± 3.4 mmol/L vs 12.0 ± 1.6 mmol/L, P = .045). Comprehensive CFTR genotyping revealed that 5 of 19 (26.3%) subjects with PSC had a CFTR mutation or variant, compared with 6 of 14 (42.9%) disease control subjects. Conclusions There is a high prevalence of CFTR-mediated ion transport dysfunction in subjects with childhood PSC.
Primary sclerosing cholangitis (PSC) and cystic fibrosis (CF) are both slowly progressive cholestatic liver diseases characterized by fibro-obliterative inflammation of the biliary tract. We ...hypothesized that dysfunction of the CF gene product, cystic fibrosis transmembrane conductance regulator (CFTR), may explain why a subset of patients with inflammatory bowel disease develop PSC. We prospectively evaluated CFTR genotype and phenotype in patients with PSC ( n=19) compared with patients with inflammatory bowel disease and no liver disease ( n=18), primary biliary cirrhosis ( n=17), CF ( n=81), and healthy controls ( n=51). Genetic analysis of the CFTR gene in PSC patients compared with disease controls (primary biliary cirrhosis and inflammatory bowel disease) demonstrated a significantly increased number of mutations/variants in the PSC group (37% vs 8.6% of disease controls, P=0.02). None of the PSC patients carried two mutations/variants. Of PSC patients, 89% carried the 1540G-variant-containing genotypes (resulting in decreased functional CFTR) compared with 57% of disease controls ( P=0.03). Only one of 19 PSC patients had neither a CFTR mutation nor the 1540G variant. CFTR chloride channel function assessed by nasal potential difference testing demonstrated a reduced median isoproterenol response of 14 mV in PSC patients compared with 19 mV in disease controls ( P=0.04) and 21 mV in healthy controls ( P=0.003). These data indicate that there is an increased prevalence of CFTR abnormalities in PSC as demonstrated by molecular and functional analyses and that these abnormalities may contribute to the development of PSC in a subset of patients with inflammatory bowel disease.
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