Fabio Majo

IL-1 receptor antagonist ameliorates inflammasome-dependent inflammation in murine and human cystic fibrosis

Dysregulated inflammasome activation contributes to respiratory infections and pathologic airway inflammation. Through basic and translational approaches involving murine models and human genetic epidemiology, we show here the importance of the different inflammasomes in regulating inflammatory responses in mice and humans with cystic fibrosis (CF), a life-threatening disorder of the lungs and digestive system. While both contributing to pathogen clearance, NLRP3 more than NLRC4 contributes to deleterious inflammatory responses in CF and correlates with defective NLRC4-dependent IL-1Ra production. Disease susceptibility in mice and microbial colonization in humans occurrs in conditions of genetic deficiency of NLRC4 or IL-1Ra and can be rescued by administration of the recombinant IL-1Ra, anakinra. These results indicate that pathogenic NLRP3 activity in CF could be negatively regulated by IL-1Ra and provide a proof-of-concept evidence that inflammasomes are potential targets to limit the pathological consequences of microbial colonization in CF.

A mast cell-ILC2-Th9 pathway promotes lung inflammation in cystic fibrosis

T helper 9 (Th9) cells contribute to lung inflammation and allergy as sources of interleukin-9 (IL-9). However, the mechanisms by which IL-9/Th9 mediate immunopathology in the lung are unknown. Here we report an IL-9-driven positive feedback loop that reinforces allergic inflammation. We show that IL-9 increases IL-2 production by mast cells, which leads to expansion of CD25+ type 2 innate lymphoid cells (ILC2) and subsequent activation of Th9 cells. Blocking IL-9 or inhibiting CD117 (c-Kit) signalling counteracts the pathogenic effect of the described IL-9-mast cell-IL-2 signalling axis. Overproduction of IL-9 is observed in expectorates from cystic fibrosis (CF) patients, and a sex-specific variant of IL-9 is predictive of allergic reactions in female patients. Our results suggest that blocking IL-9 may be a therapeutic strategy to ameliorate inflammation associated with microbial colonization in the lung, and offers a plausible explanation for gender differences in clinical outcomes of patients with CF.

Hypoxia Promotes Danger-mediated Inflammation via Receptor for Advanced Glycation End Products in Cystic Fibrosis

RATIONALE Hypoxia regulates the inflammatory-antiinflammatory balance by the receptor for advanced glycation end products (RAGE), a versatile sensor of damage-associated molecular patterns. The multiligand nature of RAGE places this receptor in the midst of chronic inflammatory diseases. OBJECTIVES To characterize the impact of the hypoxia-RAGE pathway on pathogenic airway inflammation preventing effective pathogen clearance in cystic fibrosis (CF) and elucidate the potential role of this danger signal in pathogenesis and therapy of lung inflammation. METHODS We used in vivo and in vitro models to study the impact of hypoxia on RAGE expression and activity in human and murine CF, the nature of the RAGE ligand, and the impact of RAGE on lung inflammation and antimicrobial resistance in fungal and bacterial pneumonia. MEASUREMENTS AND MAIN RESULTS Sustained expression of RAGE and its ligand S100B was observed in murine lung and human epithelial cells and exerted a proximal role in promoting inflammation in murine and human CF, as revealed by functional studies and analysis of the genetic variability of AGER in patients with CF. Both hypoxia and infections contributed to the sustained activation of the S100B-RAGE pathway, being RAGE up-regulated by hypoxia and S100B by infection by Toll-like receptors. Inhibiting the RAGE pathway in vivo with soluble (s) RAGE reduced pathogen load and inflammation in experimental CF, whereas sRAGE production was defective in patients with CF. CONCLUSIONS A causal link between hyperactivation of RAGE and inflammation in CF has been observed, such that targeting pathogenic inflammation alleviated inflammation in CF and measurement of sRAGE levels could be a useful biomarker for RAGE-dependent inflammation in patients with CF.

Fatty liver and insulin resistance in children with hypobetalipoproteinemia: the importance of aetiology.

Hepatic steatosis is strongly associated with insulin resistance, but causative mechanisms that link these conditions are still largely unknown. Nowadays, it is difficult to establish whether fatty liver is the cause of insulin resistance or instead the complex metabolic derangements of insulin resistance determine hepatic steatosis and its progression to fibrosis. In patients with familial hypobetalipoproteinemia (FHBL), hepatic steatosis is because of the genetically determined defective form of apolipoprotein B, independently of metabolic derangements. Therefore patients with FHBL represent a good in vivo model to evaluate the relationships between fatty liver and insulin sensitivity.

Glucose tolerance affects pubertal growth and final height of children with cystic fibrosis

There are few data about the impact of cystic fibrosis‐related diabetes (CFRD) on growth. We analyzed 17 children with cystic fibrosis (CF) presenting with newly diagnosed CFRD during puberty, in comparison with a matched control group of 52 CF children with normal glucose tolerance (NGT). Anthropometric evaluation showed that body mass index at CFRD diagnosis was significantly reduced in children with CFRD, in comparison with children with NGT (CFRD: −0.48 ± 1.08 vs. NGT: 0.2 ± 0.99; P = 0.01), and the same difference remained evident at the end of follow up (CFRD: −0.49 ± 0.95 vs. NGT: 0.13 ± 0.89; P = 0.04). Height standard deviation score (SDS) at baseline was slightly but not significantly lower in CFRD children (CFRD: −0.71 ± 0.83 vs. NGT: −0.25 ± 1.08; P = 0.08), while final height SDS was significantly reduced (CFRD: −1.61 ± 1.12 vs. NGT: −0.61 ± 1.15; P = 0.003). Mean final height SDS of the whole group was lower than mean target height SDS (final height SDS: −0.86 ± 1.2 vs. target height SDS: −0.3 ± 0.85; P < 0.001). Target adjusted final height was lower in CFRD children, although the difference between CFRD and NGT children did not reach statistical significance (CFRD: −0.8 ± 1.03 vs. NGT: −0.47 ± 0.9; P = 0.09). Pubertal growth and final height are negatively affected by CFRD. Intensive insulin treatment does not appear to be effective in normalizing growth, even when treatment is started early in the course of the disease, before the onset of clinical deterioration. Pediatr Pulmonol. 2015; 50:144–149.

Liposomes loaded with bioactive lipids enhance antibacterial innate immunity irrespective of drug resistance

Phagocytosis is a key mechanism of innate immunity, and promotion of phagosome maturation may represent a therapeutic target to enhance antibacterial host response. Phagosome maturation is favored by the timely and coordinated intervention of lipids and may be altered in infections. Here we used apoptotic body-like liposomes (ABL) to selectively deliver bioactive lipids to innate cells, and then tested their function in models of pathogen-inhibited and host-impaired phagosome maturation. Stimulation of macrophages with ABLs carrying phosphatidic acid (PA), phosphatidylinositol 3-phosphate (PI3P) or PI5P increased intracellular killing of BCG, by inducing phagosome acidification and ROS generation. Moreover, ABLs carrying PA or PI5P enhanced ROS-mediated intracellular killing of Pseudomonas aeruginosa, in macrophages expressing a pharmacologically-inhibited or a naturally-mutated cystic fibrosis transmembrane conductance regulator. Finally, we show that bronchoalveolar lavage cells from patients with drug-resistant pulmonary infections increased significantly their capacity to kill in vivo acquired bacterial pathogens when ex vivo stimulated with PA- or PI5P-loaded ABLs. Altogether, these results provide the proof of concept of the efficacy of bioactive lipids delivered by ABL to enhance phagosome maturation dependent antimicrobial response, as an additional host-directed strategy aimed at the control of chronic, recurrent or drug-resistant infections.

Relationship between CFTR and CTRC Variants and the Clinical Phenotype in Late-Onset Cystic Fibrosis Disease with Chronic Pancreatitis

Cystic fibrosis (CF), the most common autosomal recessive disease in whites, is caused by mutations in the CF transmembrane conductance regulator (CFTR). So far, >1900 mutations have been described, most of which are nonsense, missense, and frameshift, and can lead to severe phenotypes, reducing the level of function of the CFTR protein. Synonymous variations are usually considered silent without pathogenic effects. However, synonymous mutations exhibiting exon skipping as a consequence of aberrant splicing of pre-mRNA differ. Herein, we describe the effect of the aberrant splicing of the c.273G>C (G91G) synonymous variation found in a 9-year-old white (ΔF508) patient affected by CF and pancreatitis associated with a variant in chymotrypsin C (CTRC). Magnetic resonance imaging showed an atrophic pancreatic gland with substitution of the pancreatic parenchyma with three cysts. Genetic examination revealed compound heterozygosity for the c.1521_1523delCTT (ΔF508) pathogenic variant and the c.273G>C (G91G) variant in CFTR. Sweat test results confirmed the diagnosis of CF. We have thus identified a synonymous variation (G91G) causing the skipping of exon 3 in a CF patient carrying the ΔF508 mutation. However, the clinical phenotype with pancreatic symptoms encouraged us to investigate a panel of pancreas-related genes, which resulted in finding a known sequence variation inside CTRC. We further discuss the role of these variants and their possible interactions in determining the current phenotype.

Lack of efficacy of Lactobacillus GG in reducing pulmonary exacerbations and hospital admissions in children with cystic fibrosis: A randomised placebo controlled trial

BACKGROUND Intestinal dysbiosis has been described in Cystic Fibrosis (CF) and probiotics have been proposed to restore microbial composition. Aim of the study was to investigate the effects of Lactobacillus rhamnosus GG (LGG) on clinical outcomes in children with cystic fibrosis (CF). METHODS A multicentre, randomised double-blind, clinical trial was conducted in children with CF. After 6months of baseline assessment, enrolled children (2 to 16years of age) received Lactobacillus GG (6×109CFU/day) or placebo for 12months. Primary outcomes were proportion of subjects with at least one pulmonary exacerbation and hospitalisation over 12months. Secondary endpoints were total number of exacerbations and hospitalisations, pulmonary function, and nutritional status. RESULTS Ninety-five patients were enrolled (51/95 female; median age of 103±50months). In a multivariate GEE logistic analysis, the odds of experiencing at least one exacerbation was not significantly different between the two groups, also after adjusting for the presence of different microbial organisms and for the number of pulmonary exacerbations within 6months before randomisation (OR 0.83; 95% CI 0.38 to 1.82, p=0.643). Similarly, LGG supplementation did not significantly affect the odds of hospitalisations (OR 1.67; 95% CI 0.75 to 3.72, p=0.211). No significant difference was found for body mass index and FEV1. CONCLUSIONS LGG supplementation had no effect on respiratory and nutritional outcomes in this large study population of children with CF under stringent randomised clinical trial conditions. Whether earlier interventions, larger doses, or different strains of probiotics may be effective is unknown.

Metabolomic analysis by nuclear magnetic resonance spectroscopy as a new approach to understanding inflammation and monitoring of pharmacological therapy in children and young adults with cystic fibrosis

15-F2t-Isoprostane, a reliable biomarker of oxidative stress, has been found elevated in exhaled breath condensate (EBC), a non-invasive technique for sampling of airway secretions, in patients with cystic fibrosis (CF). Azithromycin has antioxidant properties in experimental models of CF, but its effects on oxidative stress in CF patients are largely unknown. Primary objective of this pilot, proof-of-concept, prospective, parallel group, pharmacological study, was investigating the potential antioxidant effects of azithromycin in CF patients as reflected by EBC 15-F2t-isoprostane. Secondary objectives included studying the effect of azithromycin on EBC and serum metabolic profiles, and on serum 15-F2t-isoprostane. In CF patients who were on maintenance treatment with oral vitamin E (200 UI once daily), treatment with oral azithromycin (250 or 500 mg depending on body weight) plus vitamin E (400 UI once daily) (group A) (n = 24) or oral vitamin E alone (400 UI once daily) (group B) (n = 21) was not associated with changes in EBC 15-F2t-isoprostane concentrations compared with baseline values after 8–weeks treatment or 2 weeks after treatment suspension. There was no between-group difference in post-treatment EBC 15-F2t-isoprostane. Likewise, no within- or between-group differences in serum 15-F2t-isoprostane concentrations were observed in either study group. NMR spectroscopy-based metabolomics of EBC shows that suspension of both azithromycin plus vitamin E and vitamin E alone has a striking effect on metabolic profiles in EBC. Between-group comparisons show that EBC metabolite distribution after treatment and 2 weeks after treatment suspension is different. Quantitative differences in ethanol, saturated fatty acids, acetate, acetoin/acetone, and methanol are responsible for these differences. Our study was unable to show antioxidant effect of azithromycin as add-on treatment with doubling the dose of oral vitamin E as reflected by 15-F2t-isoprostane concentrations in EBC. Add-on therapy with azithromycin itself does not induce EBC metabolite changes, but its suspension is associated with EBC metabolic profiles that are different from those observed after vitamin E suspension. The pathophysiological and therapeutic implications of these findings in patients with stable CF are unknown and require further research. Preliminary data suggest that EBC NMR-based metabolomics might be used for assessing the effects of pharmacological treatment suspension in stable CF patients.

Defining research priorities in cystic fibrosis. Can existing knowledge and training in biomedical research affect the choice

The aim of this report is to assess whether the research issues priorities are perceived differently according to the Stakeholders (SH)s individual knowledge of research topics and degree of training in biomedical research. Four groups of SH were enrolled in this study: 1. Skilled SH, specifically trained in biomedicine; 2. Unskilled untrained SH who responded to a written questionnaire in 2015; 3. SH who were trained for one year in a course delivered by professionals; 4. Untrained SH who responded to an online questionnaire in 2017. The large ranking order variability observed among groups addresses the question that the choices are markedly influenced by the SHs backgrounds. Such results emphasize the need to consider the education level and the delivery of ad hoc training activities by professionals to broaden the base of SH who may be considered qualified to transfer the Patient Centered Outcome Research principles into practice.