CFTR Protein: Not Just a Chloride Channel?

Cystic fibrosis (CF) is a recessive genetic disease caused by mutations in a gene encoding a protein called Cystic Fibrosis Transmembrane Conductance Regulator (CFTR). The CFTR protein is known to acts as a chloride (Cl-) channel expressed in the exocrine glands of several body systems where it also regulates other ion channels, including the epithelial sodium (Na+) channel (ENaC) that plays a key role in salt absorption. This function is crucial to the osmotic balance of the mucus and its viscosity. However, the pathophysiology of CF is more challenging than a mere dysregulation of epithelial ion transport, mainly resulting in impaired mucociliary clearance (MCC) with consecutive bronchiectasis and in exocrine pancreatic insufficiency. This review shows that the CFTR protein is not just a chloride channel. For a long time, research in CF has focused on abnormal Cl- and Na+ transport. Yet, the CFTR protein also regulates numerous other pathways, such as the transport of HCO3-, glutathione and thiocyanate, immune cells, and the metabolism of lipids. It influences the pH homeostasis of airway surface liquid and thus the MCC as well as innate immunity leading to chronic infection and inflammation, all of which are considered as key pathophysiological characteristics of CF.

Immunoglobulin G: A useful outcome marker in the follow-up of cystic fibrosis patients?

BACKGROUND AND METHODS: Hypergammaglobulinemia (hyper-IgG) and hypogammaglobulinemia (hypo-IgG) have been reported in patients with cystic fibrosis (CF). Although the clinical respiratory course is paradoxically different, depending on the IgG status, this association remains elusive. Therefore, we performed a longitudinal study to assess the annual evolution of IgG profiles in a cohort of pediatric patients with CF, from their diagnosis until 2016. We then compared clinical findings with the patients' IgG status to determine whether IgG status could reflect the respiratory clinical course of patients with CF. RESULTS: Among the 66 patients with CF that were aged between 12 months and 18 years in 2016 (mean age: 9.3 years [SD: 5.2]), hypo-IgG was observed in 15.2% and no hyper-IgG was identified. Longitudinal assessment since diagnosis revealed no hyper-IgG but 33.3% of patients had at least one sample showing hypo-IgG, among which two patients displayed persistent hypo-IgG. The number of pulmonary exacerbations, duration of antibiotic therapy, and erythrocyte sedimentation rate were all lower in hypo-IgG patients. No difference was observed for the genotype, chronic Pseudomonas aeruginosa or Staphylococcus aureus infection, and in the parameters of lung function. CONCLUSION: The IgG profile of pediatric patients with CF has changed over recent decades, particularly with regard to hyper-IgG. In a significant portion of the pediatric CF population, hypo-IgG is transient and only identifiable in longitudinal assessments. This study reinforces that hypo-IgG patients paradoxically present a more favorable course of clinical status. Therefore, IgG levels could be a useful outcome marker in the follow-up of patients with CF.

[Review of the sweat test indications in a Brussels' cystic fibrosis reference center]. / Revue des indications du test de la sueur dans un centre de référence de mucoviscidose bruxellois.

Sweat test is the gold standard of the diagnosis of cystic fibrosis (CF). The aim of our study was to identify the indications leading to perform a sweat test and those that led to the diagnosis of CF. METHODOLOGY: We collected data of all sweat tests performed between 2008, 1th of March and 2015, 28th of February. They were analyzed following Rosenstein diagnosis criteria (1998): clinical manifestations suggesting CF, positive neonatal screening (≥ 1 positive assay of immunoreactive trypsin) or familial history of CF. RESULTS: We reviewed 1,208 sweat tests over this period. Patients were aged from 13 days to 79 years. Indications were: clinical events (94.0%), a positive neonatal screening (3.7%) and a family history (2.3%). Over the 20 newly diagnosed patients, a positive neonatal screening was the main indication for the sweat test (55%). A positive neonatal screening (p<0.0001), a family history (p<0.0001) and pulmonary signs associated with digestive signs (p=0.004) were more frequently found in these patients. CONCLUSION: Sweat test indications are mostly clinical and mainly pulmonary. This study confirms that a sweat test should be performed in case of pulmonary manifestations suggesting CF especially if these are associated with digestive manifestations.

The Number of X Chromosomes Influences Inflammatory Cytokine Production Following Toll-Like Receptor Stimulation.

Sex differences are observed in the evolution of numerous inflammatory conditions. Women exhibit better clinical courses compared to men in acute inflammatory processes, yet worse prognosis in several chronic inflammatory diseases. Inflammatory markers are significantly different between prepubertal boys and girls, whose sex steroid levels are very low, suggesting genetics play a role. To evaluate the potential influence of the X chromosome, we studied cytokine production and protein phosphorylation following Toll-like receptor (TLR) activation in whole blood and purified neutrophils and monocytes of healthy adults of both sexes as well as subjects with Klinefelter syndrome. We recorded higher levels of inflammatory cytokines in men compared to both women and patients with Klinefelter syndrome following whole blood stimulation. In purified monocytes, production of inflammatory cytokines was also higher in men compared to women, while Klinefelter subjects expressed the same pattern of cytokine production as males, in contrast with whole blood analyses. These differences remained after adjusting for sex steroid levels. Our study revealed higher cytokine inflammatory responses in men than women, yet also compared to subjects with Klinefelter syndrome, who carry two copies of the X chromosome, like women, and thus potentially benefit from the cellular mosaicism of X-linked genes.

Immunologic mechanisms of a short-course of Lolium perenne peptide immunotherapy: A randomized, double-blind, placebo-controlled trial.

BACKGROUND: A 3-week short-course of adjuvant-free hydrolysates of Lolium perenne peptide (LPP) immunotherapy for rhinoconjunctivitis with or without asthma over 4 physician visits is safe, well tolerated, and effective. OBJECTIVE: We sought to investigate immunologic mechanisms of LPP immunotherapy in a subset of patients who participated in a phase III, multicenter, randomized, double-blind, placebo-controlled trial (clinical.govNCT02560948). METHODS: Participants were randomized to receive LPP (n = 21) or placebo (n = 11) for 3 weeks over 4 visits. Grass pollen-induced basophil, T-cell, and B-cell responses were evaluated before treatment (visit [V] 2), at the end of treatment (V6), and after the pollen season (V8). RESULTS: Combined symptom and rescue medication scores (CSMS) were lower during the peak pollen season (-35.1%, P = .03) and throughout the pollen season (-53.7%, P = .03) in the LPP-treated group compared with those in the placebo-treated group. Proportions of CD63+ and CD203cbrightCRTH2+ basophils were decreased following LPP treatment at V6 (10 ng/mL, P < .0001) and V8 (10 ng/mL, P < .001) compared to V2. No change in the placebo-treated group was observed. Blunting of seasonal increases in levels of grass pollen-specific IgE was observed in LPP-treated but not placebo-treated group. LPP immunotherapy, but not placebo, was associated with a reduction in proportions of IL-4+ TH2 (V6, P = .02), IL-4+ (V6, P = .003; V8, P = .004), and IL-21+ (V6, P = .003; V8, P = .002) follicular helper T cells. Induction of FoxP3+, follicular regulatory T, and IL-10+ regulatory B cells were observed at V6 (all P < .05) and V8 (all P < .05) in LPP-treated group. Induction of regulatory B cells was associated with allergen-neutralizing IgG4-blocking antibodies. CONCLUSION: For the first time, we demonstrate that the immunologic mechanisms of LPP immunotherapy are underscored by immune modulation in the T- and B-cell compartments, which is necessary for its effect.

The Acid-Base Balance and Gender in Inflammation: A Mini-Review.

In humans, acid-base balance is crucial to cell homeostasis. Acidosis is observed in numerous inflammatory processes, primarily acute conditions such as sepsis, trauma, or acute respiratory distress where females tend to exhibit better prognosis compared with males. The mechanisms underlying these gender-dependent differences are multiple, probably involving hormonal and genetic factors, particularly the X chromosome. Although pH influences multiple immunological functions, gender differences in acid-base balance have been poorly investigated. In this review, we provide an update on gender differences in human susceptibility to inflammatory diseases. We additionally discuss the potential impact of acid-base balance on the gender bias of the inflammatory response in view of our recent observation that girls present higher neutrophilic inflammation and lower pH with a trend toward better prognosis in severe sepsis. We also highlight the potent role played by endothelial cells in gender differences of inflammation through activation of proton-sensing G protein-coupled receptors.

Differential Susceptibility to Infectious Respiratory Diseases between Males and Females Linked to Sex-Specific Innate Immune Inflammatory Response.

It is widely acknowledged that males and females exhibit contrasting degrees of susceptibility to infectious and non-infectious inflammatory diseases. This is particularly observed in respiratory diseases where human males are more likely to be affected by infection-induced acute inflammations compared to females. The type and magnitude of the innate immune inflammatory response play a cardinal role in this sex bias. Animal models mimicking human respiratory diseases have been used to address the biological factors that could explain the distinct outcomes. In this review, we focus on our current knowledge about experimental studies investigating sex-specific differences in infection-induced respiratory diseases and we provide an update on the most important innate immune mechanisms that could explain sex bias of the inflammatory response. We also discuss whether conclusions drawn from animal studies could be relevant to human.

Sex Differences in Inflammatory Response and Acid-Base Balance in Prepubertal Children with Severe Sepsis.

PURPOSE AND METHODS: The severity and prognosis of various acute inflammatory conditions, such as sepsis, differ between males and females. The mechanisms underlying these sex differences probably involve both hormonal and genetic factors. In order to evaluate a possible genetic influence, we reviewed clinical signs and biological inflammatory markers of prepubertal children with severe sepsis admitted to the pediatric intensive care unit (PICU). FINDINGS: A total of 142 prepubertal children, 66 girls and 76 boys, suffering from severe sepsis and admitted to the PICU were included. The survival rate demonstrated a tendency to be higher in females (P = 0.14). Maximum white blood cell count (23,800 cells/µL [15,110-34,600] in girls vs. 19,025 cells/µL [12,358-26,098] in boys, P = 0.02), neutrophil count (16,944 cells/µL [10,620-27,540] vs. 13,756 cells/µL [8410-20,110], P = 0.03), and C-reactive protein level (26.2 mg/dL [15.7-33.6] vs. 18.8 mg/dL [11.1-30.0], P = 0.04) were all significantly higher in girls. Girls also exhibited significantly longer fever duration (2 days [1-6] vs. 1 day [1-3] for the boys, P <0.01), lower pH on admission (7.32 [7.25-7.39] vs. 7.37 [7.31-7.43] P = 0.03), and lower base excess (-6 mEq/L [-10.7 to -0.8] vs. -2.3 mEq/L [-6.6 to -2.6], P <0.01), as well as lower bicarbonate levels (19.1 mEq/l [15.9-24.0] vs. 21.15 mEq/l [18.3-26.68], P = 0.04), when compared with the boys. CONCLUSIONS: Our study revealed higher neutrophilic inflammation, as well as lower pH on admission, in girls with severe sepsis; associated with longer fever duration, which could contribute to better pathogen clearance. However, further studies are needed to demonstrate the link between acidosis and modulation of the immune response.

Sex and inflammation in respiratory diseases: a clinical viewpoint.

This review discusses sex differences in the prognosis of acute or chronic inflammatory diseases. The consequences of severe inflammation vary in relation to sex, depending on illness duration. In the majority of acute diseases, males present higher mortality rates, whereas continuous chronic inflammation associated with tissue damage is more deleterious in females. The recruitment of cells, along with its clinical expression, is more significant in females, as reflected by higher inflammatory markers. Given that estrogens or androgens are known to modulate inflammation, their different levels in males and females cannot account for the sexual dimorphism observed in humans and animals from birth to death with regard to inflammation. Numerous studies evaluated receptors, cytokine production, and clinical outcomes in both animals and humans, revealing that estrogens clearly modulate the immune response, but the results are contradictory and difficult to link to hormone concentrations. Even in prepubescent children, the presentation of acute pneumonia or chronic diseases mimics the adult pattern. Several genes located on the X chromosome have been shown to encode molecules involved in inflammation. Moreover, 10% to 15% of the genes from silenced X chromosome may escape inhibition. Females are also a mosaic of cells with genes from either paternal or maternal X chromosome. Therefore, polymorphism of X-linked genes would result in the presence of two cell populations with distinct regulatory arsenals, providing females with greater diversity to fight against infectious challenges, in comparison with the uniform cell populations in hemizygous males. The similarities observed between males and Turner syndrome patients using an endotoxin stimulation model support the difference in gene expression between monosomy and disomy for the X chromosome. Considering the enhanced inflammation in females, cytokine production may be assumed to be higher in females than males. Even if all results are not clear-cut, nonetheless, many studies have reported higher cytokine levels in both male humans and animals than in females. High IL-6 levels in males correlated with poorer prognosis and shorter longevity. A sound understanding of the basic regulatory mechanisms responsible for these gender differences may lead to new therapeutic targets.

Sex differences in inflammatory cytokines and CD99 expression following in vitro lipopolysaccharide stimulation.

Sex influences the severity and evolution of various inflammatory conditions. Although many studies have demonstrated the role of sex hormones in immune response modulation, recent clinical data revealed significant sex differences in inflammatory markers in prepubertal children, suggesting a genetic contribution. We studied several immune functions depending on X-linked genes in healthy adults of both sexes: the respiratory burst of purified neutrophils, the CD99 and CD11b expression of stimulated leukocytes as markers of adhesion and diapedesis, and the production of inflammatory cytokines in whole blood after incubation with lipopolysaccharide for 24 h. The percentage of monocytes expressing CD99 was higher in men than in women, thus confirming the higher CD99 expression reported in males using reverse transcription-polymerase chain reaction. In addition, we observed a higher tumor necrosis factor α and tendency toward higher interleukin (IL) 6 production in men after lipopolysaccharide stimulation. These differences may contribute to the higher mortality reported in men with septic shock. Tumor necrosis factor α production significantly correlated with monocyte count, with men having a higher monocyte count than women. When cytokine levels were normalized to monocyte counts, a higher IL-8 production was found in women, which may explain the higher neutrophil count observed in girls with acute inflammatory diseases, because IL-8 is a major neutrophil chemoattractant. These sex differences regarding the activation of certain X-linked genes involved in innate immunity confirm our clinical observations, thus supporting the role of sex chromosomes in inflammatory response.

Gender differences and inflammation: an in vitro model of blood cells stimulation in prepubescent children.

BACKGROUND: Gender influences clinical presentations and markers in inflammatory diseases. In many chronic conditions, frequency of complications is greater in females, suggesting that continuous inflammatory reaction may induce greater damage in targeted organs and functions. METHODS: To investigate gender dimorphism at a cellular level, we evaluated the production of cytokines implicated in inflammatory processes (IL -1, IL- 6, PGE-2 and TNF alpha), in healthy prepubescent children of both sex and Turner's syndrome (TS) patients (genotype XO). We used stimulation by LPS (0.2 and 1 ng/ml) and Pokeweed Mitogen (PWM) on overnight cultures from whole blood samples, collected in 57 subjects: 22 girls/26 boys (5-96 months), and 9 TS patients (6-15 years). The primary outcome was to evaluate if gender influences the production of cytokines, with potential relation to X chromosome monosomy. Secondary endpoints were to relate different cytokines level productions and conditions. RESULTS: We confirm the male over female increased cytokine productions already observed in adults. This is contrasting with numerous observations obtained in vivo about increased production of inflammatory markers in females (CRP, ESR and neutrophil counts), as we recently reported in children. Relative variations of the dimorphism according to stimulus, its concentration and cytokine type are discussed, presenting IL6 with a modulating function that could be more potent in males. TS subjects follow mostly the male pattern of reactivity, sustaining the role of some gene expression differing with X chromosome monosomy and disomy. CONCLUSIONS: Persistence of the latter dimorphism throughout life casts doubts on its direct relationship with individual hormonal status, as already documented by others in vitro, and supports the need for alternative hypothesis, such as the influence of X chromosome gene products escaping X inactivation in females and absent in subjects with X monosomy (males, TS).

Gender differences in inflammatory markers in children.

No clear explanation exists to understand how sex hormones and/or chromosomes affect the immune system. In vitro studies of human lymphoid cells also show sex differences in immune function. To evaluate these differences in frequent pediatric emergencies, we analyze the expression of inflammatory markers (C-reactive protein, erythrocyte sedimentation rate, and neutrophil count) underlying inflammatory processes in children: 482 children (241 girls and 241 boys) hospitalized for pneumonia (n = 384), pyelonephritis (n = 39), or bronchiolitis (n = 59) matched for age and sex. All patients were younger than 10 years. A control population of 97 children (50 girls and 47 boys) admitted for day surgery (tonsillectomy, circumcision, or strabismus) was included. We observed highly significant differences between girls and boys: median C-reactive protein concentration of 5.45 mg/dL (range, 0.2-36.0 mg/dL) for girls and 2.6 mg/dL (range, 0.3-37.3 mg/dL) for boys (P < 0.0001), and median erythrocyte sedimentation rate of 39.5 mm/h (range, 2-104 mm/h) for girls and 24 mm/h (range, 4-140 mm/h) for boys (P < 0.005). Neutrophil counts were also significantly different: a median of 8,796 cells/microL (range, 328-27,645 cells/microL) for girls and 6,774 cells/microL (range, 600-38,668 cells/microL) for boys (P < 0.02). The duration of fever after initiating antibiotic therapy was longer in girls than in boys, but there was no difference (Fisher exact test, P < 0.06). The present study documents a relationship between sex and both the production of inflammatory markers and neutrophil recruitment. Sex difference also showed more direct clinical relevance with associations seen between sex and both duration of fever and duration of disease (bronchiolitis P < 0.0007).

Chronic inflammatory diseases in children are more severe in girls.

In humans and animal models, females express higher immune reactivity and more robust inflammatory responses. We analyzed the expression of current inflammatory markers in 149 children (74 girls and 75 boys) with three chronic inflammatory diseases: 50 with asthma, 47 with cystic fibrosis, and 52 with sickle cell anemia to evaluate the potential differences in clinical response according to sex. Data including temperature, neutrophil count (NC), and C-reactive protein were recorded for each patient at several time points according to his/her disease. In asthma, NC was higher in girls than in males (P < 0.02), as were doses of cortisone (P < 0.04) or inhaled bronchodilators (P < 0.01) received at recovery. In cystic fibrosis, NC became significantly higher in girls at age 5 years (P < 0.003), whereas episodes of infection and antibiotic administration were already significantly more frequent in girls at age 2 years (P < 0.02 and P < 0.05, respectively). In sickle cell anemia, the number of crises since diagnosis and number of acute chest syndrome episodes were significantly higher in girls (P < 0.01 and P < 0.05, respectively). Our study extends the documentation of a relationship between sex, inflammatory markers, and clinical outcome in prepubescent children, suggesting a genetic predetermination is more likely than hormonal influence.

Effect of systemic inflammation on inspiratory and limb muscle strength and bulk in cystic fibrosis.

RATIONALE: Diaphragm thickness is increased in cystic fibrosis (CF), but it shows a marked variability between patients. The variable response of the diaphragm to loading may reflect the combined and opposite effects of training by the respiratory disease and systemic inflammation. OBJECTIVES: To assess the impact of systemic inflammation on diaphragm and limb muscle strength and bulk in adult patients with CF. METHODS: In 38 stable patients with CF and 20 matched control subjects, we measured fat-free mass (FFM), inspiratory muscle strength, diaphragm thickness, quadriceps and biceps strength and cross-sectional area, and circulating levels of leukocytes, C-reactive protein, IL-6, IL-8, IL-17, tumor necrosis factor-alpha, tumor necrosis factor-alpha soluble receptors, and immunoglobulin G. MEASUREMENTS AND MAIN RESULTS: Patients had increases in several inflammatory markers that correlated with the severity of lung disease and nutritional depletion. Compared with control subjects, patients with CF had increased diaphragm thickness and inspiratory muscle strength and showed a trend toward a reduction in limb muscle strength and bulk. Multiple regression analyses identified FFM and airway resistance as independent predictors of diaphragm thickness, but systemic inflammation had no (or only a minor) predictive effect on FFM, inspiratory muscle strength, diaphragm thickness, and limb muscle strength and bulk. CONCLUSIONS: In patients with CF, the intensity of systemic inflammation does not account significantly for the variance of FFM and diaphragm or limb muscle strength and bulk. Training of the diaphragm in CF occurs despite the presence of systemic inflammation.

Anti DNA antibodies are not restricted to a specific pattern of fluorescence on HEp2 cells.

BACKGROUND: Antinuclear autoantibody determination relies on an initial screening step using immunofluorescence on HEp2 cells. This may be followed by anti-deoxyribonucleic acid (DNA) determination, if the fluorescence of nuclei is homogeneous. We assessed the validity of a restricted algorithm and compared this to a more comprehensive algorithm that accepted any nuclear pattern as a positive indicator. METHODS: Our retrospective study analyzed routine results for antinuclear antibodies (ANA) and their anti-DNA identification [double stranded nuclear DNA (ds-DNA), membrane associated DNA (mDNA), nucleosomes] for 58 systemic lupus erythematosus (SLE) patients (690 sera). We included 158 patients with systemic or organ-specific autoimmune diseases (888 sera), 44 with viral disease (88 sera), 34 cancer patients (89 sera) and 111 patients with inflammation that served as controls (122 sera) for a total of 1187 samples. RESULTS: 1) Anti DNA antibodies are not associated only with a homogeneous pattern, but can also be seen with a speckled or nucleolar pattern. 2) The observed pattern is typical for a particular patient rather than for a specific pathology. 3) A homogeneous pattern does not necessarily indicate SLE, nor does the presence of circulating anti DNA antibodies. 4) Determination of various specificities of anti DNA antibodies, whatever the immunofluorescent pattern, increases the sensitivity and specificity for SLE. CONCLUSIONS: If diagnosis is based exclusively on a homogenous pattern, preselection would have missed identification of SLE as high levels of anti DNA antibodies were also associated with speckled or nucleolar pattern.

Current practices in antinuclear antibody testing: results from the Belgian External Quality Assessment Scheme.

BACKGROUND: This study aimed to assess the state-of-the-art of antinuclear antibody (ANA) testing as practiced in the Belgian and Luxembourg laboratories, using the results obtained in the Belgian National External Quality Assessment Scheme from 2000 to 2005. METHODS: During this period, nine samples with different specificities were sent for analysis. Participants were surveyed for methodology used and were asked to report staining pattern and titer of ANAs. In 2002, an attempt was made to improve the comparability of quantitative ANA results by the provision of a commercial reference material and to relate observed differences to methodology. RESULTS: With one exception, all participants employed a microscope-based indirect immunofluorescence assay with human epithelial cell line 2 cells. Most laboratories were accurate in describing the pattern. The percentage of unacceptable answers was greater for samples with borderline levels of antibody and for samples showing a cytoplasmic pattern. An improvement in the detection of anticentromere antibodies was observed. For all samples, a wide range of titers was reported. The provision of the secondary reference preparation led to improved inter-laboratory concordance. Comparison of methodology variables revealed a correlation between unstandardized titers and the power of the lamp of the microscope and the use of a dark room. CONCLUSIONS: The EQAS results presented in this work provide valuable insights into the state of the art of ANA testing as practiced in the Belgian and Luxembourg Laboratories and illustrate the important value of a national EQAS for ANA testing as a tool to improve performance and interlaboratory comparability of laboratory results.

Cytokines and brain injury: invited review.

The brain reacts to injury or disease by cascades of cellular and molecular responses. Evidence suggests that immune-inflammatory processes are key elements in the physiopathological processes associated with brain injury or damage. Cytokines are among major mediators implicated in these processes. Cytokine responses in the initial phase of brain injury might have a role in aggravating brain damage. However, in later stages, these molecular mediators might contribute to recovery or repair. Hemodynamic stabilization and optimalization of oxygen delivery to the brain remain cornerstones in the management of acute brain injury. New approaches might use anticytokine therapy to limit progression and halt or attenuate secondary brain damage. Progress toward such novel neuroprotection strategies, however, awaits better understanding of the optimal timing and dosing of those neuromodulatory therapies and better knowledge of the numerous interactions of those mediators. This also requires understanding of how and when precisely immune mechanisms shift from noxious to protective or restorative actions.