Salivary Cytokines and Airways Disease Severity in Patients with Cystic Fibrosis

About 50% of patients with cystic fibrosis (CF) have sinonasal complications, which include inferior turbinate hypertrophy (NTH) and/or nasal polyposis (NP), and different degrees of lung disease, which represents the main cause of mortality. Monitoring of sinonasal disease requires complex instrumental procedures, while monitoring of lung inflammation requires invasive collection of bronchoalveolar lavage fluid. The aim of this study was to investigate the associations between salivary cytokines levels and CF-related airway diseases. Salivary biochemical parameters and cytokines, i.e., interleukin-6 (IL-6), IL-8, and tumor necrosis factor alpha (TNF-α), were analyzed in resting saliva from healthy subjects and patients with CF. Patients with CF showed significantly higher levels of salivary chloride, IL-6, IL-8, and TNF-α and lower calcium levels than healthy subjects. Among patients with CF, IL-6 and IL-8 were significantly higher in patients with NTH, while TNF-α was significantly lower in patients with NP. A decreasing trend of TNF-α in patients with severe lung disease was also observed. On the other hand, we did not find significant correlation between cytokine levels and Pseudomonas aeruginosa or Stenotrophomonas maltophilia colonization. These preliminary results suggest that salivary IL-6 and IL-8 levels increase during the acute phase of sinonasal disease (i.e., NTH), while the end stages of pulmonary disease and sinonasal disease (i.e., NP) show decreased TNF-α levels.

An investigation on parenting stress of children with cystic fibrosis

Background

The management of chronic diseases, particularly in children, requires an integrated physical and psychological approach to both sick children and their family. This is the case of Cystic Fibrosis (CF), a complex genetic chronic disease, where, a comprehensive evaluation of the emotional impact and an effective multidimensional approach are indicated.

Aim

This study investigates on parenting stress in children and adolescents with CF and its determinants related to parents, children and the disease severity.

Methods

The study involved 34.04% adult males and 65.96% adult females (range 21-55 years) and 47 children with CF, 54.35% males and 45.65% females (range 1-17 years). The data were obtained through a Parenting Stress Index – Short Form (PSI-SF) questionnaire. According to the PSI-SF scoring system, three types of stress were detected: a typical stress pattern (normal), a high stress pattern (increased) and a defensive response, which may be considered as a high stress feature in children which requires monitoring and clinical evaluation.

Results

This study shows a significant presence of stress in females (60.23%), of subject married (84.62%), unemployed (69.23%) and with education level such as “middle School” (61.54%). Concerning children of parents with high stress, it resulted most frequent children with one sibling (53.85%). Finally, by univariate analysis, it resulted a significant positive correlation between parenting stress and disease degree of children. Instead by multivariate analysis, we found that the variables: Number of siblings and Birth order were a significant positive and negative predictor of parenting stress respectively.

Conclusion

An increased stress level was detected in less than one third of parents of subjects with CF. These data may be related to the psychological support which is part of the routine management of CF care team. However, as children’s features seem to act as a determinant of stress more than parental ones, the parental-child dysfunction should be the target for further integrated interventions.

Does virtual reality reduce pain in pediatric patients? A systematic review

Virtual Reality (VR) as a tool for pain reduction is the research topic of several clinical trial for Randomized Controlled Trials despite its wide use in the daily clinical practice for non- pharmacological reduction of pain in some countries. At present, there are no published reviews of VR-efficacy of pain reduction in pediatric patients. That is why we made a systematic review of the efficacy of VR as a tool for pain reduction in children and adolescents. Electronic databases and gray literature published between 2014 and 2019 were analyzed. A total of 9 studies were eligible according to the established inclusion criteria. Results show that virtual reality is a valid tool for non-pharmacological pain reduction and that this approach is to be preferred to the standard reduction techniques currently in use. However, more studies using standardized experimental methodologies are needed to provide more systematic comparison and quantitative synthesis.

IL-9 and Mast Cells Are Key Players of Candida albicans Commensalism and Pathogenesis in the Gut

Candida albicans is implicated in intestinal diseases. Identifying host signatures that discriminate between the pathogenic versus commensal nature of this human commensal is clinically relevant. In the present study, we identify IL-9 and mast cells (MCs) as key players of Candida commensalism and pathogenicity. By inducing TGF-β in stromal MCs, IL-9 pivotally contributes to mucosal immune tolerance via the indoleamine 2,3-dioxygenase enzyme. However, Candida-driven IL-9 and mucosal MCs also contribute to barrier function loss, dissemination, and inflammation in experimental leaky gut models and are upregulated in patients with celiac disease. Inflammatory dysbiosis occurs with IL-9 and MC deficiency, indicating that the activity of IL-9 and MCs may go beyond host immunity to include regulation of the microbiota. Thus, the output of the IL-9/MC axis is highly contextual during Candida colonization and reveals how host immunity and the microbiota finely tune Candida behavior in the gut.

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IL-9/IL-9R signaling affects MC function in mucosal candidiasis

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IL-9 and mucosal MCs contribute to barrier function loss in leaky gut models

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IL-9 and stromal MCs induce local protective tolerance in infection via IDO1

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IL-9 and mucosal MCs expand and IDO1 decreases in human celiac disease

GH-IGF-1 Axis in Children with Cystic Fibrosis

OBJECTIVE

To verify whether growth hormone receptor (GHR) gene expression plays a role in growth of children with cystic fibrosis (CF), as a consequence of the chronic inflammatory condition and malnutrition.

DESIGN

We enrolled 49 prepubertal patients (24 males and 25 females) affected by CF in a stable clinical condition, 19 of whom had been diagnosed through newborn screening and 30 following presentation of symptoms. Patients had no significant comorbidity affecting growth or cystic fibrosis transmembrane conductance regulator (CFTR)-related diabetes requiring insulin therapy. Blood was collected during two follow-up visits to measure insulin-like growth factor (IGF-I), growth hormone-binding protein (GHBP), and GHR gene expression. Recruited as a control group were 52 healthy children, sex- and age-matched, were recruited as a control group.

METHODS

We compared body mass index (BMI), height, weight, IGF-I, GHBP, and GHR gene expression values (evaluated by Chemiluminescent Immunometric assay; ELISA and real-time PCR, respectively) in CF patients diagnosed through newborn screening (NBS) or by symptoms (late diagnosis [LD]) and in healthy controls.

RESULTS

BMI increased significantly in patients between the time of diagnosis and check-up (P<0.001), particularly in the LD group; median value was lower at diagnosis and significantly higher (P<0.001) at follow-up visits compared to controls. At initial evaluation, higher levels of IGF-I (not statistically significant) were found in both the NBS group and the LD group compared to the control group. At the second evaluation, significantly higher levels of IGF-I (P=0.003) were found in both the NBS and LD groups compared to controls; GHR mRNA expression had significantly increased (P=0.013) in LD patients compared with the first evaluation and was significantly higher in the NBS and LD groups than in controls. GHBP values had significantly increased (P=0.047) in the NBS group after one year of therapy compared to first visit levels and were significantly higher (P<0,0001) in the NBS and LD groups compared to controls.

CONCLUSION

In our LD patients during childhood, we observed good auxological values and a GH/IGF-I axis function within normal range for the factor evaluated. However, earlier diagnosis through NBS might further minimize and prevent growth retardation, by reducing the duration of symptoms before treatment.

Cystic fibrosis transmembrane conductance regulator (CFTR) and autophagy: hereditary defects in cystic fibrosis versus gluten-mediated inhibition in celiac disease

Cystic Fibrosis (CF) is the most frequent lethal monogenetic disease affecting humans. CF is characterized by mutations in cystic fibrosis transmembrane conductance regulator (CFTR), a chloride channel whose malfunction triggers the activation of transglutaminase-2 (TGM2), as well as the inactivation of the Beclin-1 (BECN1) complex resulting in disabled autophagy. CFTR inhibition, TGM2 activation and BECN1 sequestration engage in an ‘infernal trio’ that locks the cell in a pro-inflammatory state through anti-homeostatic feedforward loops. Thus, stimulation of CFTR function, TGM2 inhibition and autophagy stimulation can be used to treat CF patients. Several studies indicate that patients with CF have a higher incidence of celiac disease (CD) and that mice bearing genetically determined CFTR defects are particularly sensitive to the enteropathogenic effects of the orally supplied gliadin (a gluten-derived protein). A gluten/gliadin-derived peptide (P31–43) inhibits CFTR in mouse intestinal epithelial cells, causing a local stress response that contributes to the immunopathology of CD. In particular, P31–43-induced CFTR inhibition elicits an epithelial stress response perturbing proteostasis. This event triggers TGM2 activation, BECN1 sequestration and results in molecular crosslinking of CFTR and P31-43 by TGM2. Importantly, stimulation of CFTR function with a pharmacological potentiator (Ivacaftor), which is approved for the treatment of CF, could attenuate the autophagy-inhibition and pro-inflammatory effects of gliadin in preclinical models of CD. Thus, CD shares with CF a common molecular mechanism involving CFTR inhibition that might respond to drugs that intercept the "infernal trio". Here, we highlight how drugs available for CF treatment could be repurposed for the therapy of CD.

Methicillin-resistant Staphylococcus aureus eradication in cystic fibrosis patients: A randomized multicenter study

BACKGROUND

Few studies, based on a limited number of patients using non-uniform therapeutic protocols, have analyzed Methicillin-resistant Staphylococcus aureus (MRSA) eradication.

METHODS

In a randomized multicenter trial conducted on patients with new-onset MRSA infection we evaluated the efficacy of an early eradication treatment (arm A) compared with an observational group (B). Arm A received oral rifampicin and trimethoprim/sulfamethoxazole (21 days). Patients' microbiological status, FEV1, BMI, pulmonary exacerbations and use of antibiotics were assessed.

RESULTS

Sixty-one patients were randomized. Twenty-nine (47.5%) patients were assigned to active arm A and 32 (52.5%) patients to observational arm B. Twenty-nine (47.5%) patients, 10 patients in arm A and 19 in arm B, dropped out of the study. At 6 months MRSA was eradicated in 12 (63.2%) out of 19 patients in arm A while spontaneous clearance was observed in 5 (38.5%) out of 13 patients in arm B. A per-protocol analysis showed a 24.7% difference in the proportion of MRSA clearance between the two groups (z = 1.37, P(Z>z) = 0.08). Twenty-seven patients, 15 (78.9%) out of 19 in arm A and 12 (92.3%) out of 13 in arm B, were able to perform spirometry. The mean (±SD) FEV1 change from baseline was 7.13% (±14.92) in arm A and -1.16% (±5.25) in arm B (p = 0.08). In the same period the BMI change (mean ±SD) from baseline was 0.54 (±1.33) kg/m2 in arm A and -0.38 (±1.56) kg/m2 in arm B (p = 0.08). At 6 months no statistically significant differences regarding the number of pulmonary exacerbations, days spent in hospital and use of antibiotics were observed between the two arms.

CONCLUSIONS

Although the statistical power of the study is limited, we found a 24.7% higher clearance of MRSA in the active arm than in the observational arm at 6 months. Patients in the active arm A also had favorable FEV1 and BMI tendencies.

The gliadin-CFTR connection: new perspectives for the treatment of celiac disease

Familial loss-of-function mutations of the gene coding for the cystic fibrosis transmembrane conductance regulator (CFTR) channel protein cause cystic fibrosis (CF), the most frequent inherited life-threatening disease in the Caucasian population. A recent study indicates that the gluten/gliadin-derived peptide (P31–43) can cause CFTR inhibition in intestinal epithelial cells, thus causing a local stress response that contributes to the immunopathology of celiac disease (CD). Accordingly, an increased prevalence of CD has been observed in several cohorts of CF patients. CD is characterized by a permanent intolerance to gluten/gliadin proteins occurring in a proportion of susceptible individuals who bear the human leukocyte antigen (HLA) DQ2/DQ8. In CD, perturbations of the intestinal environment, together with the activation of the innate immune system by P31–43, are essential for rendering other immunodominant gliadin peptide fully antigenic, thus triggering an adaptive immune response with an autoimmune component. P31–43-induced CFTR inhibition elicits the danger signals that ignite the epithelial stress response and perturb epithelial proteostasis. Importantly, potentiators of CFTR channel gating, such as the FDA-approved drug Ivacaftor, prevent P31–43 driven CFTR inhibition and suppress the gliadin-induced stress response in cells from celiac patients, as well as the immunopathology developing in gliadin-sensitive mice. Thus, CFTR potentiators may represent a novel therapeutic option for celiac patients.

Autophagy suppresses the pathogenic immune response to dietary antigens in cystic fibrosis

Under physiological conditions, a finely tuned system of cellular adaptation allows the intestinal mucosa to maintain the gut barrier function while avoiding excessive immune responses to non-self-antigens from dietary origin or from commensal microbes. This homeostatic function is compromised in cystic fibrosis (CF) due to loss-of-function mutations in the CF transmembrane conductance regulator (CFTR). Recently, we reported that mice bearing defective CFTR are abnormally susceptible to a celiac disease-like enteropathy, in thus far that oral challenge with the gluten derivative gliadin elicits an inflammatory response. However, the mechanisms through which CFTR malfunction drives such an exaggerated response to dietary protein remains elusive. Here we demonstrate that the proteostasis regulator/transglutaminase 2 (TGM2) inhibitor cysteamine restores reduced Beclin 1 (BECN1) protein levels in mice bearing cysteamine-rescuable F508del-CFTR mutant, either in homozygosis or in compound heterozygosis with a null allele, but not in knock-out CFTR mice. When cysteamine restored BECN1 expression, autophagy was increased and gliadin-induced inflammation was reduced. The beneficial effects of cysteamine on F508del-CFTR mice were lost when these mice were backcrossed into a Becn1 haploinsufficient/autophagy-deficient background. Conversely, the transfection-enforced expression of BECN1 in human intestinal epithelial Caco-2 cells mitigated the pro-inflammatory cellular stress response elicited by the gliadin-derived P31–43 peptide. In conclusion, our data provide the proof-of-concept that autophagy stimulation may mitigate the intestinal malfunction of CF patients.

Personalization of therapies in rare diseases: a translational approach for the treatment of cystic fibrosis

High variability in the response rates to treatments can make the interpretation of data from clinical trials very difficult, particularly in rare genetic diseases in which the enrolment of thousands of patients is problematic. Personalized medicine largely depends on the establishment of appropriate early detectors of drug efficacy that may guide the administration (or discontinuation) of specific treatments. Such biomarkers should be capable of predicting the therapeutic response of individual patients and of monitoring early benefits of candidate drugs before late clinical benefits become evident. The identification of these biomarkers implies a rigorous stepwise process of translation from preclinical evaluation in cultured cells, suitable animal models or patient-derived freshly isolated cells to clinical application. In this review, we will discuss how a process of research translation can lead to the implementation of functional and mechanistic disease-relevant biomarkers. Moreover, we will address how preclinical data can be translated into the clinic in a personalized medical approach that can provide the right drug to the right patient within the right timeframe.

Inhaled medications in cystic fibrosis beyond antibiotics

Structural lung disease begins very early in children with cystic fibrosis (CF), often in the first three months of life. Inhaled medications represent an attractive therapeutic approach in CF that are routinely used as early intervention strategies. Two aerosolized solutions, hypertonic saline and dornase alfa, have significant potential benefits by improving mucociliary clearance, with minimal associated side-effects. In particular, they favor rehydration of airway surface liquid and cleavage of extracellular DNA in the airways, respectively, consequently reducing rate of pulmonary disease exacerbations. Indirect anti-inflammatory effects have been documented for both drugs, addressing each of the three interrelated elements in the vicious cycle of lung disease in CF: airway obstruction, inflammation and infection. This short review aimed to summarize the main papers that support potential clinical impact of inhaled solutions on pulmonary disease in CF.

Defective proteostasis in celiac disease as a new therapeutic target

Cystic fibrosis (CF) is a disease caused by loss-of-function mutations affecting the CF transmembrane conductance regulator (CFTR), a chloride channel. Recent evidence indicates that CFTR is inhibited by a gluten/gliadin-derived peptide (P31-43), causing an acquired state of CFTR inhibition within the gut that contributes to the pathogenesis of celiac disease (CD). Of note, CFTR inhibition does not only cause intra- and extracellular ion imbalances but also affects proteostasis by activating transglutaminase-2 (TGM2) and by disabling autophagy. These three phenomena (CFTR inhibition, TGM2 activation, and autophagy impairment) engage in multiple self-amplifying circuitries, thus forming an "infernal trio". The trio hinders enterocytes from returning to homeostasis and instead locks them in an irreversible pro-inflammatory state that ultimately facilitates T lymphocyte-mediated immune responses against another gluten/gliadin-derived peptide (P57-68), which,upon deamidation by activated TGM2, becomes fully antigenic. Hence, the pathogenic protein gliadin exemplifies a food constituent the exceptional immunogenicity of which arises from a combination of antigenicity (conferred by deaminated P57-68) and adjuvanticity (conferred by P31-43). CF can be treated by agents targeting the "infernal trio" including CFTR potentiators, TGM2 inhibitors, and autophagy enhancers. We speculate that such agents may also be used for CD therapy and indeed could constitute close-to-etiological treatments of this enteropathy.

Clinical expression of cystic fibrosis in a large cohort of Italian siblings

Background

A clinical heterogeneity was reported in patients with Cystic Fibrosis (CF) with the same CFTR genotype and between siblings with CF.

Methods

We investigated all clinical aspects in a cohort of 101 pairs of siblings with CF (including 6 triplets) followed since diagnosis.

Results

Severe lung disease had a 22.2% concordance in sib-pairs, occurred early and the FEV₁% at 12 years was predictive of the severity of lung disease in the adulthood. Similarly, CF liver disease occurred early (median: 15 years) and showed a concordance of 27.8% in sib-pairs suggesting a scarce contribution of genetic factors; in fact, only 2/15 patients with liver disease in discordant sib-pairs had a deficiency of alpha-1-antitrypsin (a known modifier gene of CF liver phenotype). CF related diabetes was found in 22 pairs (in 6 in both the siblings). It occurred later (median: 32.5 years) and is strongly associated with liver disease. Colonization by P. aeruginosa and nasal polyposis that required surgery had a concordance > 50% in sib-pairs and were poorly correlated to other clinical parameters. The pancreatic status was highly concordant in pairs of siblings (i.e., 95.1%) but a different pancreatic status was observed in patients with the same CFTR mutations. This suggests a close relationship of the pancreatic status with the “whole” CFTR genotype, including mutations in regulatory regions that may modulate the levels of CFTR expression. Finally, a severe course of CF was evident in a number of patients with pancreatic sufficiency.

Conclusions

Physicians involved in care of patients with CF and in genetic counseling must be aware of the clinical heterogeneity of CF even in sib-pairs that, at the state of the art, is difficult to explain.

Electronic supplementary material

The online version of this article (10.1186/s12890-018-0766-6) contains supplementary material, which is available to authorized users.

A pathogenic role for cystic fibrosis transmembrane conductance regulator in celiac disease

Intestinal handling of dietary proteins usually prevents local inflammatory and immune responses and promotes oral tolerance. However, in ~ 1% of the world population, gluten proteins from wheat and related cereals trigger an HLA DQ2/8‐restricted T_H1 immune and antibody response leading to celiac disease. Prior epithelial stress and innate immune activation are essential for breaking oral tolerance to the gluten component gliadin. How gliadin subverts host intestinal mucosal defenses remains elusive. Here, we show that the α‐gliadin‐derived LGQQQPFPPQQPY peptide (P31–43) inhibits the function of cystic fibrosis transmembrane conductance regulator (CFTR), an anion channel pivotal for epithelial adaptation to cell‐autonomous or environmental stress. P31–43 binds to, and reduces ATPase activity of, the nucleotide‐binding domain‐1 (NBD1) of CFTR, thus impairing CFTR function. This generates epithelial stress, tissue transglutaminase and inflammasome activation, NF‐κB nuclear translocation and IL‐15 production, that all can be prevented by potentiators of CFTR channel gating. The CFTR potentiator VX‐770 attenuates gliadin‐induced inflammation and promotes a tolerogenic response in gluten‐sensitive mice and cells from celiac patients. Our results unveil a primordial role for CFTR as a central hub orchestrating gliadin activities and identify a novel therapeutic option for celiac disease.

Trans-heterozygosity for mutations enhances the risk of recurrent/chronic pancreatitis in patients with Cystic Fibrosis

BACKGROUND

Recurrent (RP) and chronic pancreatitis (CP) may complicate Cystic Fibrosis (CF). It is still unknown if mutations in genes involved in the intrapancreatic activation of trypsin (IPAT) or in the pancreatic secretion pathway (PSP) may enhance the risk for RP/CP in patients with CF.

METHODS

We enrolled: 48 patients affected by CF complicated by RP/CP and, as controls 35 patients with CF without pancreatitis and 80 unrelated healthy subjects. We tested a panel of 8 genes involved in the IPAT, i.e. PRSS1, PRSS2, SPINK1, CTRC, CASR, CFTR, CTSB and KRT8 and 23 additional genes implicated in the PSP.

RESULTS

We found 14/48 patients (29.2%) with mutations in genes involved in IPAT in the group of CF patients with RP/CP, while mutations in such genes were found in 2/35 (5.7%) patients with CF without pancreatitis and in 3/80 (3.8%) healthy subjects (p < 0.001). Thus, we found mutations in 12 genes of the PSP in 11/48 (22.9%) patients with CF and RP/CP. Overall, 19/48 (39.6%) patients with CF and RP/CP showed one or more mutations in the genes involved in the IPAT and in the PSP while such figure was 4/35 (11.4%) for patients with CF without pancreatitis and 11/80 (13.7%) for healthy controls (p < 0.001).

CONCLUSIONS

The trans-heterozygous association between CFTR mutations in genes involved in the pathways of pancreatic enzyme activation and the pancreatic secretion may be risk factors for the development of recurrent or chronic pancreatitis in patients with CF.

Intra-individual biological variation in sweat chloride concentrations in CF, CFTR dysfunction, and healthy pediatric subjects

BACKGROUND

The sweat test is one of the main diagnostic tools used in newborn screening programs and as a confirmatory test, in case of suspect of Cystic Fibrosis (CF). Since sweat chloride (Cl) concentration is also considered an appropriate parameter to explore the efficacy of CFTR modulators in clinical trials, it is crucial to evaluate the biological variability of this test in healthy and pathological conditions. The aim of this pilot study was to determine the intra-individual biological variability of sweat Cl, both in healthy individuals and CF patients and to assess its correlation with diet, season, and menstrual cycle.

METHODS

Thirty-five out of 36 selected subjects (6-18 years) were enrolled by 2 CF care centers and assigned to 3 cohorts: CF, CFTR-related disorder (CFTR-RD) and healthy volunteers. Each participant was subjected to eight sweat tests in different conditions and time of the year. Data were analyzed using linear mixed effects models for repeated measures, taking also into account intra-individual correlations.

RESULTS

We observed a high intra-individual variability of sweat Cl, with the lowest mean CV% values among CF patients (20.21 in CF, 29.74 in CFTR-RD, and 31.15 in healthy subjects). Gender and diet had no influence on sweat Cl variability, nor had pubertal age and menstrual phase.

CONCLUSION

Results of this pilot study confirmed that sweat Cl variability is high in CF patients, although non-CF individuals displayed even higher mean CV% values. Season significantly influenced sweat test values only in CF patients, likely due to changes in their hydration status.

An "ex vivo model" contributing to the diagnosis and evaluation of new drugs in cystic fibrosis

Cystic fibrosis (CF) is an autosomal recessive disease caused by mutations in the cystic fibrosis transmembrane regulator (CFTR) gene. About 2000 mutations have been described so far. We setup an ex vivo model of human nasal epithelial cells (HNECs) to study CF patients testing the effect of novel mutations and molecular therapies. We performed sampling (by brushing), followed by culture and analysis of HNECs using a series of molecular techniques. We performed 50 brushings from CF patients and controls. Using cultured cells, we: i) demonstrated the widely heterogeneous CFTR expression in patients and in controls; ii) defined the splicing effect of a CFTR mutation; iii) assessed the CFTR gating activity in patients bearing different mutations; iv) demonstrated that butyrate significantly enhances CFTR expression. Based on our data, we can conclude: 1) HNEC brushing is performed without anaesthesia and is well tolerated in all CF patients (children and adults); 2) HNECs can be preserved for up to 48 hours before culture allowings multicentre studies; 3) HNECs culture can be considered a suitable model to study the molecular effects of new CFTR gene mutations and/or uncertain meaning specific mutations of carriers; 4) an ex vivo model of HNECs may be used to evaluate, before human use, the effect of new drugs on patients’ cells bearing specific CFTR mutations; 5) the methodology is adequate for a quantitative measurement, by fluorescence, of the CFTR gating activity of the HNECs from patients with different genotypes identifying: a) CF patients bearing two severe mutations with an activity < 10% (compared to controls – 100%); b) CF patients bearing at least a mild mutation with an activity of 10-20%; c) CF carriers (heterozygous subjects) with an activity between 40-70%.

TG2 regulates the heat-shock response by the post-translational modification of HSF1

Heat-shock factor 1 (HSF1) is the master transcription factor that regulates the response to proteotoxic stress by controlling the transcription of many stress-responsive genes including the heat-shock proteins. Here, we show a novel molecular mechanism controlling the activation of HSF1. We demonstrate that transglutaminase type 2 (TG2), dependent on its protein disulphide isomerase activity, triggers the trimerization and activation of HSF1 regulating adaptation to stress and proteostasis impairment. In particular, we find that TG2 loss of function correlates with a defect in the nuclear translocation of HSF1 and in its DNA-binding ability to the HSP70 promoter. We show that the inhibition of TG2 restores the unbalance in HSF1-HSP70 pathway in cystic fibrosis (CF), a human disorder characterized by deregulation of proteostasis. The absence of TG2 leads to an increase of about 40% in CFTR function in a new experimental CF mouse model lacking TG2. Altogether, these results indicate that TG2 plays a key role in the regulation of cellular proteostasis under stressful cellular conditions through the modulation of the heat-shock response.

S737F is a new CFTR mutation typical of patients originally from the Tuscany region in Italy

Background

An increasing number of patients have been described as having a number of Cystic Fibrosis Transmembrane conductance Regulator (CFTR) variants for which it lacks a clear genotype–phenotype correlation. We assesses the clinical features of patients bearing the S737F (p.Ser737Phe) CFTR missense variant and evaluated the residual function of CFTR protein on nasal epithelial cells (NEC).

Methods

A retrospective database was performed from individuals homozygous or compound heterozygous for the S737F variant followed in the Cystic Fibrosis (CF) Centre of Florence. We performed a nasal brushing in cooperating patients and compared the results with those of patients followed in the pediatric CF Centre of Naples.

Results

9/295 (3%) subjects carrying at least S737F CFTR variant on one allele were identified. Patients were diagnosed in 7/9 cases by newborn screening and in two cases for dehydration with hypochloremic metabolic alkalosis; at diagnosis sweat chloride levels (SCL) were in the pathological range in only one case. After a mean follow up of 8,6 years (range 0,5–15,8), SCL were in the pathological range in 8/9 cases (mean age at CF diagnosis: 1,5 years), all patients were pancreatic sufficiency and respiratory function was normal. The gating activity on NEC was 15.6% and 12.7% in two patients compound heterozygous for W1282X and DelE22_24, while it was ranged between 6,2% and 9,8% in CF patients.

Conclusions

S737F is a CFTR mutation associated to hypochloremic alkalosis in childhood, mild CF phenotype in teenage years and a residual function of CFTR protein.