Valeria Raia

Association between innate response to gliadin and activation of pathogenic T cells in coeliac disease

BACKGROUND The adaptive immune system is central to the development of coeliac disease. Adaptive immune responses are, however, controlled by a preceding activation of the innate immune system. We investigated whether gliadin, a protein present in wheat flour, could activate an innate as well as an adaptive immune response in patients with coeliac disease. METHODS Duodenal biopsy samples from 42 patients with untreated coeliac disease, 37 treated patients, and 18 controls, were cultured in vitro for 3 h or 24 h, in the presence of either immunodominant gliadin epitopes (p(alpha)-2 and p(alpha)-9) or a non-immunodominant peptide (p31-43) known to induce small intestine damage in coeliac disease. We also incubated biopsy samples from nine untreated and six treated patients with a non-immunodominant peptide for 3 h, before incubation with immunodominant gliadin epitopes. Different combinations of interleukin-15 or signal transduction inhibitors were added to selected incubations. FINDINGS Only the non-immunodominant peptide induced rapid expression of interleukin-15, CD83, cyclo-oxygenase (COX)-2, and CD25 by CD3- cells (p=0.005 vs medium alone) and enterocyte apoptosis (p<0.0001). Only the non-immunodominant peptide induced p38 MAP kinase activation in CD3- cells. Pre-incubation with the non-immunodominant peptide enabled immunodominant epitopes to induce T-cell activation (p=0.001) and enterocyte apoptosis. Inhibition of interleukin-15 or of p38 MAP kinase controlled such activity. INTERPRETATION A gliadin fragment can activate the innate immune system, affecting the in situ T-cell recognition of dominant gliadin epitopes. Although our findings emphasise the key role of gliadin-specific T cells, they suggest a complex pathogenic situation, and show that inhibition of interleukin-15 or p38 MAP kinase might have the potential to control coeliac disease.

Defective CFTR induces aggresome formation and lung inflammation in cystic fibrosis through ROS-mediated autophagy inhibition

Accumulation of unwanted/misfolded proteins in aggregates has been observed in airways of patients with cystic fibrosis (CF), a life-threatening genetic disorder caused by mutations in the gene encoding the cystic fibrosis transmembrane conductance regulator (CFTR). Here we show how the defective CFTR results in defective autophagy and decreases the clearance of aggresomes. Defective CFTR-induced upregulation of reactive oxygen species (ROS) and tissue transglutaminase (TG2) drive the crosslinking of beclin 1, leading to sequestration of phosphatidylinositol-3-kinase (PI(3)K) complex III and accumulation of p62, which regulates aggresome formation. Both CFTR knockdown and the overexpression of green fluorescent protein (GFP)-tagged-CFTRF508del induce beclin 1 downregulation and defective autophagy in non-CF airway epithelia through the ROS–TG2 pathway. Restoration of beclin 1 and autophagy by either beclin 1 overexpression, cystamine or antioxidants rescues the localization of the beclin 1 interactome to the endoplasmic reticulum and reverts the CF airway phenotype in vitro, in vivo in Scnn1b-transgenic and CftrF508del homozygous mice, and in human CF nasal biopsies. Restoring beclin 1 or knocking down p62 rescued the trafficking of CFTRF508del to the cell surface. These data link the CFTR defect to autophagy deficiency, leading to the accumulation of protein aggregates and to lung inflammation.

Targeting the Intracellular Environment in Cystic Fibrosis: Restoring Autophagy as a Novel Strategy to Circumvent the CFTR Defect

Cystic fibrosis (CF) patients harboring the most common deletion mutation of the CF transmembrane conductance regulator (CFTR), F508del, are poor responders to potentiators of CFTR channel activity which can be used to treat a small subset of CF patients who genetically carry plasma membrane (PM)-resident CFTR mutants. The misfolded F508del-CFTR protein is unstable in the PM even if rescued by pharmacological agents that prevent its intracellular retention and degradation. CF is a conformational disease in which defective CFTR induces an impressive derangement of general proteostasis resulting from disabled autophagy. In this review, we discuss how rescuing Beclin 1 (BECN1), a major player of autophagosome formation, either by means of direct gene transfer or indirectly by administration of proteostasis regulators, could stabilize F508del-CFTR at the PM. We focus on the relationship between the improvement of peripheral proteostasis and CFTR PM stability in F508del-CFTR homozygous bronchial epithelia or mouse lungs. Moreover, this article reviews recent pre-clinical evidence indicating that targeting the intracellular environment surrounding the misfolded mutant CFTR instead of protein itself could constitute an attractive therapeutic option to sensitize patients carrying the F508del-CFTR mutation to the beneficial action of CFTR potentiators on lung inflammation.

Intestinal inflammation is a frequent feature of cystic fibrosis and is reduced by probiotic administration

Aims : To assess the incidence of intestinal inflammation in children with cystic fibrosis and to investigate whether probiotics decrease it.

Urea-induced ROS generation causes insulin resistance in mice with chronic renal failure

Although supraphysiological concentrations of urea are known to increase oxidative stress in cultured cells, it is generally thought that the elevated levels of urea in chronic renal failure patients have negligible toxicity. We previously demonstrated that ROS increase intracellular protein modification by O-linked beta-N-acetylglucosamine (O-GlcNAc), and others showed that increased modification of insulin signaling molecules by O-GlcNAc reduces insulin signal transduction. Because both oxidative stress and insulin resistance have been observed in patients with end-stage renal disease, we sought to determine the role of urea in these phenotypes. Treatment of 3T3-L1 adipocytes with urea at disease-relevant concentrations induced ROS production, caused insulin resistance, increased expression of adipokines retinol binding protein 4 (RBP4) and resistin, and increased O-GlcNAc-modified insulin signaling molecules. Investigation of a mouse model of surgically induced renal failure (uremic mice) revealed increased ROS production, modification of insulin signaling molecules by O-GlcNAc, and increased expression of RBP4 and resistin in visceral adipose tissue. Uremic mice also displayed insulin resistance and glucose intolerance, and treatment with an antioxidant SOD/catalase mimetic normalized these defects. The SOD/catalase mimetic treatment also prevented the development of insulin resistance in normal mice after urea infusion. These data suggest that therapeutic targeting of urea-induced ROS may help reduce the high morbidity and mortality caused by end-stage renal disease.

Tissue Transglutaminase Activation Modulates Inflammation in Cystic Fibrosis via PPARγ Down-Regulation

Cystic fibrosis (CF), the most common life-threatening inherited disease in Caucasians, is due to mutations in the CF transmembrane conductance regulator (CFTR) gene and is characterized by airways chronic inflammation and pulmonary infections. The inflammatory response is not secondary to the pulmonary infections. Indeed, several studies have shown an increased proinflammatory activity in the CF tissues, regardless of bacterial infections, because inflammation is similarly observed in CFTR-defective cell lines kept in sterile conditions. Despite recent studies that have indicated that CF airway epithelial cells can spontaneously initiate the inflammatory cascade, we still do not have a clear insight of the molecular mechanisms involved in this increased inflammatory response. In this study, to understand these mechanisms, we investigated ex vivo cultures of nasal polyp mucosal explants of CF patients and controls, CFTR-defective IB3-1 bronchial epithelial cells, C38 isogenic CFTR corrected, and 16HBE normal bronchial epithelial cell lines. We have shown that a defective CFTR induces a remarkable up-regulation of tissue transglutaminase (TG2) in both tissues and cell lines. The increased TG2 activity leads to functional sequestration of the anti-inflammatory peroxisome proliferator-activated receptor γ and increase of the classic parameters of inflammation, such as TNF-α, tyrosine phosphorylation, and MAPKs. Specific inhibition of TG2 was able to reinstate normal levels of peroxisome proliferator-activated receptor-γ and dampen down inflammation both in CF tissues and CFTR-defective cells. Our results highlight an unpredicted central role of TG2 in the mechanistic pathway of CF inflammation, also opening a possible new wave of therapies for sufferers of chronic inflammatory diseases.

NMR spectroscopy metabolomic profiling of exhaled breath condensate in patients with stable and unstable cystic fibrosis

Background Metabolomics could provide new insights into the pathophysiology of cystic fibrosis (CF) by identifying profiles of endogenous metabolites. Objectives To investigate whether metabolomics of exhaled breath condensate could discriminate between patients with unstable CF, stable CF and healthy subjects, and whether selected metabolites were responsible for between-group differences. Methods Twenty-nine patients with stable CF, 24 with unstable CF and 31 healthy subjects (age 9–24 years) participated in a cross-sectional study. Metabolomics was performed with high-resolution nuclear magnetic resonance spectroscopy. Partial least squares-discriminant analysis was used as classifier. The results were validated in a second independent study. Results Intraclass correlation coefficients for between-day and technical repeatability were 0.93 and 0.96, respectively. Bland–Altman analysis showed good within-day repeatability. Correct classification rate of CF (n=53) vs healthy subjects (n=31) was 96% (R2=0.84; Q2=0.79). Model validation with a testing sample set obtained from subjects not included in the primary analysis (23 CF and 25 healthy subjects) showed a sensitivity of 91% and a specificity of 96%. The classification rate of stable CF (n=29) vs unstable CF patients (n=24) was 95% (R2=0.82; Q2=0.78). Model external validation in 14 patients with stable CF and 16 with unstable CF showed a sensitivity of 86% and a specificity of 94%. Ethanol, acetate, 2-propanol and acetone were most discriminant between patients with CF and healthy subjects, whereas acetate, ethanol, 2-propanol and methanol were the most important metabolites for discriminating between patients with stable and unstable CF. Conclusions Nuclear magnetic resonance spectroscopy of exhaled breath condensate is reproducible, discriminates patients with CF from healthy subjects and patients with unstable CF from those with stable CF, and identifies the metabolites responsible for between-group differences.

An overview of international literature from cystic fibrosis registries: 2. Neonatal screening and nutrition/growth

BACKGROUND This is the second article related to a review of the literature based on data from national cystic fibrosis (CF) registries up to June 2008 and covering a total of 115 studies. It focuses on two topics: neonatal screening (NS) and nutritional status, with particular reference to growth. METHODS Ten papers meeting the inclusion criteria were found on the topic of NS and its impact on the course of the disease, and were analyzed according to a dedicated grid. The issue of nutrition was addressed by 14 studies, analyzed according to similar criteria. RESULTS Most of the studies report benefits of early diagnosis by NS, albeit to variable degrees. The benefits were assessed in terms of better nutritional status and growth, but also in terms of lower overall morbidity rate as compared to subjects diagnosed by symptoms. The main biases of these studies, which partly undermine the validity of their results, are also analyzed. A part of our analysis on nutrition/growth is dedicated to the identification of the most suitable parameters to define malnutrition: in children older than two years the body mass index percentile (BMIp) appears to be the most sensitive and significantly associated with respiratory function. Better nutritional status and satisfactory growth appear to be associated with better lung function and lower risk of death. The relationship between nutritional status and socio-economic status is also of interest. CONCLUSIONS CF registry studies support the outcome of cohort observational studies i.e. that pre-symptomatic early diagnosis is beneficial, especially in terms of nutritional status and growth. Studies on nutrition indicate that good nutritional status is associated with better respiratory function and prognosis. Regarding methods, the need emerged to manage potential biases of this kind of non randomized studies, resorting to suitable statistical techniques, such as matching and stratification and, above all, to multivariate methods able to provide estimates adjusted for the main covariates tested.

Effect of an 8-month treatment with omega-3 fatty acids (eicosapentaenoic and docosahexaenoic) in patients with cystic fibrosis

BACKGROUND Supplementation of the diet with eicosapentaenoic acid and docosahexaenoic acid, the main long-chain omega-3 fatty acids in cell membranes, may have beneficial effects in patients with cystic fibrosis. METHODS A prospective study involving 30 patients and 20 control subjects was carried out; eicosapentaenoic plus docosahexaenoic acid was equal to 1.3% of caloric intake in the cystic fibrosis patients. Our present study included the evaluation of eicosapentaenoic and docosahexaenoic acid incorporation into erythrocyte membranes and biological and clinical effects in response to long-term (8 months) supplementation with fish oil as a source of eicosapentaenoic and docosahexaenoic acids in patients with cystic fibrosis. RESULTS Baseline erythrocyte membrane fatty acids showed low levels of linoleic acid and eicosapentaenoic acid and mild elevation of 18:3n6, but similar docosahexanoic acid and other fatty acids in cystic fibrosis patients compared with controls. Fish oil supplementation led to a 1.7-fold (p < .05) and 1.3-fold (not significant) increase of eicosapentaenoic acid in erythrocyte membrane phospholipids after 4 and 8 months of supplementation, respectively, and to a 1.67-fold (p < .05) and 1.38-fold (p < .05) increase of docosahexanoic acid, respectively. Along with these changes, there was a progressive decrease of arachidonic acid (from 8.51 to 6.67 g/100 fatty acids at 4 months and 4.83 g/100 fatty acids at 8 months; p < .05) and an increase of linoleic acid (p < .05) in membrane phospholipids. Analysis of inflammatory markers showed a significant decrease of serum immunoglobulin G (IgG) and of alpha-1 antitrypsin (p < .05) concentrations. Pulmonary function testing showed mild but significant improvement of forced expiratory volume (FEV)-1 from 61% +/- 19% to 57% +/- 19% of predicted values (p < .05). The number of days of antibiotic therapy during the study period was markedly lower compared with the preceding 8-month period (392 versus 721 days; p < .05). CONCLUSION Long-term eicosapentaenoic plus docosahexanoic acid supplementation (8 months) has positive effects, such as decreasing inflammation, in cystic fibrosis.

Disrupted Intestinal Microbiota and Intestinal Inflammation in Children with Cystic Fibrosis and Its Restoration with Lactobacillus GG: A Randomised Clinical Trial

Background & Aims Intestinal inflammation is a hallmark of cystic fibrosis (CF). Administration of probiotics can reduce intestinal inflammation and the incidence of pulmonary exacerbations. We investigated the composition of intestinal microbiota in children with CF and analyzed its relationship with intestinal inflammation. We also investigated the microflora structure before and after Lactobacillus GG (LGG) administration in children with CF with and without antibiotic treatment. Methods The intestinal microbiota were analyzed by denaturing gradient gel electrophoresis (DGGE), real-time polymerase chain reaction (RT-PCR), and fluorescence in situ hybridization (FISH). Intestinal inflammation was assessed by measuring fecal calprotectin (CLP) and rectal nitric oxide (rNO) production in children with CF as compared with healthy controls. We then carried out a small double-blind randomized clinical trial with LGG. Results Twenty-two children with CF children were enrolled in the study (median age, 7 years; range, 2–9 years). Fecal CLP and rNO levels were higher in children with CF than in healthy controls (184±146 µg/g vs. 52±46 µg/g; 18±15 vs. 2.6±1.2 µmol/L NO2 −, respectively; P<0.01). Compared with healthy controls, children with CF had significantly different intestinal microbial core structures. The levels of Eubacterium rectale, Bacteroides uniformis, Bacteroides vulgatus, Bifidobacterium adolescentis, Bifidobacterium catenulatum, and Faecalibacterium prausnitzii were reduced in children with CF. A similar but more extreme pattern was observed in children with CF who were taking antibiotics. LGG administration reduced fecal CLP and partially restored intestinal microbiota. There was a significant correlation between reduced microbial richness and intestinal inflammation. Conclusions CF causes qualitative and quantitative changes in intestinal microbiota, which may represent a novel therapeutic target in the treatment of CF. Administration of probiotics restored gut microbiota, supporting the efficacy of probiotics in reducing intestinal inflammation and pulmonary exacerbations. Trial Registration ClinicalTrials.gov NCT 01961661