Lung disease severity, chronic inflammation, iron deficiency, and erythropoietin response in adults with cystic fibrosis

Analysis of iron status after initiation of elexacaftor/tezacaftor/ivacaftor in people with cystic fibrosis

BACKGROUND

Iron deficiency is highly prevalent in people with cystic fibrosis (PwCF). While elexacaftor/tezacaftor/ivacaftor (ETI) has shown remarkable improvements in respiratory symptoms in PwCF, the effect of ETI on iron status remains unknown. This study aims to identify the effect of ETI on iron status in PwCF.

METHODS

A single-center retrospective cohort study of 127 adult PwCF was conducted to assess the impact of ETI on iron, ferritin, transferrin levels, and percent saturation of transferrin (PSAT). Data were collected from the electronic medical record from January 2017 to September 2022, encompassing 2 years before and after ETI initiation. The primary outcome was serum iron parameters: iron, ferritin, transferrin, and PSAT levels following ETI treatment. Secondary outcomes analyzed iron supplementation. Univariate and multivariate mixed-effects models were used for the analysis of ETI.

RESULTS

After adjusting for covariates, following ETI initiation, the mean iron level increased by 20.24 μg/dL (p < .001), ferritin levels were 31.4% (p < .001) higher, PSAT showed a 5.09 percentage point increase (p < .001), and transferrin levels increased by 2.71 mg/dL (p = .439). Patients with and without iron supplementation experienced a significant increase in iron after ETI (p < .001).

CONCLUSIONS

ETI is associated with a significant increase in iron, ferritin, and PSAT levels. Patients with and without iron supplementation demonstrated a significant increase in iron. This study shows the benefits of ETI on iron status in PwCF. However, further translational studies are required to understand the impact of ETI on iron absorption and metabolism in PwCF.

Iron Deficiency in Cystic Fibrosis: A Cross-Sectional Single-Centre Study in a Referral Adult Centre

Iron deficiency (ID) diagnosis in cystic fibrosis (CF) is challenging because of frequent systemic inflammation. We aimed to determine the prevalence and risk factors of ID in adult patients with CF. We conducted a single-centre prospective study in a referral centre. ID was defined by transferrin saturation ≤16% or ferritin ≤20 (women) or 30 (men) μg/L, or ≤100 μg/L in the case of systemic inflammation. Apparent exacerbation was an exclusion criterion. We included 165 patients (78 women), mean age—31.1 ± 8.9 years. ID prevalence was 44.2%. ID was significantly associated with female gender (58.9% vs. 38%), lower age (29.4 ± 8.5 vs. 32.5 ± 9.1), lower body mass index (20.5 ± 2.2 vs. 21.3 ± 2.5), and Pseudomonas aeruginosa colonization (70.8% vs. 55.1%). Diabetes mellitus, antiacid drug use and low pulmonary function were more frequent in patients with ID with no statistical significance. The use of CFTR correctors was not associated with ID. In the multivariate analysis, ID was associated with female gender (OR 2.64, CI95% 1.31−5.31), age < 30 years (OR 2.30, CI95% 1.16−4.56), and P. aeruginosa (OR 2.09, CI95% 1.04−4.19).

Use of proton pump inhibitors is associated with lower hemoglobin levels in people with cystic fibrosis

BACKGROUND

Proton pump inhibitors (PPIs) and histamine H2-receptor antagonists (H2RAs) are commonly prescribed to people with cystic fibrosis (PwCF) to treat gastroesophageal reflux disease (GERD) and/or protect pancreatic enzymes from degradation in the stomach. Acid suppressive medications (ASMs) could theoretically reduce hemoglobin (Hgb) levels by restricting enteral iron absorption, but evidence of an association between use of ASMs and lower Hgb levels is lacking in PwCF.

METHODS

We used unadjusted and covariate-adjusted generalized linear mixed models (GLMMs) to estimate the fixed effects of using versus never using ASMs on annual Hgb levels of PwCF in the U.S. Cystic Fibrosis Foundation Patient Registry (CFFPR) from 2011 to 2017.

RESULTS

There were 9850 users and 9007 never-users of ASMs from 2011 to 2017 who met inclusion criteria. Not adjusting for covariates, Hgb estimates were lower for male and female H2RA and/or PPI users versus never-users. Adjusting for covariates, mean Hgb was 0.1 g/dl (95% CI: 0.03, 0.17) lower for males that exclusively used PPIs than it was for male never-users of ASMs (p = .008). Adjusting for covariates, mean Hgb levels were 0.11 g/dl (95% CI: 0.04, 0.18) lower for females that exclusively used PPIs and 0.16 g/dl (95% CI: 0.05, 0.27) lower for females that used PPIs and H2RAs concurrently than it was for female never-users of ASMs (p = .005 and p = .002 for respective comparisons).

CONCLUSIONS

Males and females with cystic fibrosis (CF) who used PPIs and females with CF who concurrently used PPIs and H2RAs had lower Hgb levels than never-users of ASMs of the same sex in the CFFPR from 2011 to 2017.

The role of CD71+ erythroid cells in the regulation of the immune response

Complex regulation of the immune response is necessary to support effective defense of an organism against hostile invaders and to maintain tolerance to harmless microorganisms and autoantigens. Recent studies revealed previously unappreciated roles of CD71⁺ erythroid cells (CECs) in regulation of the immune response. CECs physiologically reside in the bone marrow where erythropoiesis takes place. Under stress conditions, CECs are enriched in some organs outside of the bone marrow as a result of extramedullary erythropoiesis. However, the role of CECs goes well beyond the production of erythrocytes. In neonates, increased numbers of CECs contribute to their vulnerability to infectious diseases. On the other side, neonatal CECs suppress activation of immune cells in response to abrupt colonization with commensal microorganisms after delivery. CECs are also enriched in the peripheral blood of pregnant women as well as in the placenta and are responsible for the regulation of feto-maternal tolerance. In patients with cancer, anemia leads to increased frequency of CECs in the peripheral blood contributing to diminished antiviral and antibacterial immunity, as well as to accelerated cancer progression. Moreover, recent studies revealed the role of CECs in HIV and SARS-CoV-2 infections. CECs use a full arsenal of mechanisms to regulate immune response. These cells suppress proinflammatory responses of myeloid cells and T-cell proliferation by the depletion of ʟ-arginine by arginase. Moreover, CECs produce reactive oxygen species to decrease T-cell proliferation. CECs also secrete cytokines, including transforming growth factor β (TGF-β), which promotes T-cell differentiation into regulatory T-cells. Here, we comprehensively describe the role of CECs in orchestrating immune response and indicate some therapeutic approaches that might be used to regulate their effector functions in the treatment of human conditions.

Nutritional immunity: the impact of metals on lung immune cells and the airway microbiome during chronic respiratory disease

Nutritional immunity is the sequestration of bioavailable trace metals such as iron, zinc and copper by the host to limit pathogenicity by invading microorganisms. As one of the most conserved activities of the innate immune system, limiting the availability of free trace metals by cells of the immune system serves not only to conceal these vital nutrients from invading bacteria but also operates to tightly regulate host immune cell responses and function. In the setting of chronic lung disease, the regulation of trace metals by the host is often disrupted, leading to the altered availability of these nutrients to commensal and invading opportunistic pathogenic microbes. Similarly, alterations in the uptake, secretion, turnover and redox activity of these vitally important metals has significant repercussions for immune cell function including the response to and resolution of infection. This review will discuss the intricate role of nutritional immunity in host immune cells of the lung and how changes in this fundamental process as a result of chronic lung disease may alter the airway microbiome, disease progression and the response to infection.

Limb muscle size and contractile function in adults with cystic fibrosis: A systematic review and meta-analysis

BACKGROUND

There is conflicting evidence regarding the presence of limb muscle impairments in adults with cystic fibrosis (CF), and the factors associated with these muscle impairments. The objectives of this study were to compare limb muscle size and function between adults with CF and healthy controls; and to examine their associations with demographic and clinical variables in adults with CF.

METHODS

The systematic review was performed using PRISMA guidelines. Studies were included if they measured any aspect of limb muscle size or function in adults with CF. Meta-analyses were performed to compare muscle variables between CF and healthy controls; and to examine their associations with demographic and clinical variables.

RESULTS

Twenty-eight studies were included, with 747 adults with CF. The meta-analyses showed that adults with CF have smaller thigh muscles [standardized mean difference (SMD) = 0.57, p<.0011, I²=0%], and lower handgrip strength (SMD = 0.89, p=.0034, I²=74.03%), which was weakly correlated with forced expiratory volume in one second (FEV₁) (r=0.24, p=.035, I²=0%) and lower in females with CF (SMD = 2.05, p<.0001, I²=0%). There is no significant difference between adults with CF and controls in knee extensor strength (SMD = 0.25, p=.095, I²=42.79%).

CONCLUSIONS

Leg muscle atrophy and lower handgrip strength were noted. There may be a subgroup of adults with CF with knee extensor (quadriceps) weakness. Future studies are needed to better understand muscle impairments in people with CF; to explore the factors that can predict these muscle impairments; and to investigate their clinical significance in people with CF.

Prevalence and Risk Factors for Iron Deficiency in Adults With Cystic Fibrosis

BACKGROUND

Iron deficiency is common in cystic fibrosis (CF), but previous prevalence studies often reported results confounded by acute exacerbations. This single-center retrospective study aimed to identify the prevalence of iron deficiency in a stable adult CF population, identify the risk factors associated with iron deficiency, and compare common laboratory indicators of iron status.

METHODS

Medical charts of 105 patients aged 18-67 were reviewed to determine the prevalence of anemia. Of these patients, a subgroup of 67 were included in analyses of iron deficiency, defined as serum ferritin < 12 ng/mL and/or percent transferrin saturation (TSAT) < 16%. Data on sex, age, body mass index, anemia status, vitamin deficiencies, presence of comorbidities, colonization with Pseudomonas aeruginosa, and use of acid blockers and CF transmembrane conductance regulator modulators were collected to evaluate relationship of iron deficiency with these clinical factors. κ agreements between serum iron, ferritin, transferrin, and TSAT were compared.

RESULTS

In this stable CF population, the prevalence of iron deficiency was 41.8% (n = 67), and the prevalence of anemia was 33.3% (n = 105). Iron deficiency was associated with presence of anemia (P < .001), vitamin A deficiency (P = .012), and moderate (P = .047) and severe lung disease (P = .045) compared with mild lung disease. Transferrin agreed poorly with other iron status indicators.

CONCLUSION

Iron deficiency is common in CF, although prevalence rates can vary widely depending on the laboratory parameters used. CF centers should consider routine screening for iron deficiency.

Iron and Sphingolipids as Common Players of (Mal)Adaptation to Hypoxia in Pulmonary Diseases

Hypoxia, or lack of oxygen, can occur in both physiological (high altitude) and pathological conditions (respiratory diseases). In this narrative review, we introduce high altitude pulmonary edema (HAPE), acute respiratory distress syndrome (ARDS), Chronic Obstructive Pulmonary Disease (COPD), and Cystic Fibrosis (CF) as examples of maladaptation to hypoxia, and highlight some of the potential mechanisms influencing the prognosis of the affected patients. Among the specific pathways modulated in response to hypoxia, iron metabolism has been widely explored in recent years. Recent evidence emphasizes hepcidin as highly involved in the compensatory response to hypoxia in healthy subjects. A less investigated field in the adaptation to hypoxia is the sphingolipid (SPL) metabolism, especially through Ceramide and sphingosine 1 phosphate. Both individually and in concert, iron and SPL are active players of the (mal)adaptation to physiological hypoxia, which can result in the pathological HAPE. Our aim is to identify some pathways and/or markers involved in the physiological adaptation to low atmospheric pressures (high altitudes) that could be involved in pathological adaptation to hypoxia as it occurs in pulmonary inflammatory diseases. Hepcidin, Cer, S1P, and their interplay in hypoxia are raising growing interest both as prognostic factors and therapeutical targets.

Anaemia and iron dysregulation: untapped therapeutic targets in chronic lung disease?

Hypoxia is common in many chronic lung diseases. Beyond pulmonary considerations, delivery of oxygen (O₂) to the tissues and subsequent O₂ utilisation is also determined by other factors including red blood cell mass and iron status; consequently, disruption to these mechanisms provides further physiological strains on an already stressed system. O₂ availability influences ventilation, regulates pulmonary blood flow and impacts gene expression throughout the body. Deleterious effects of poor tissue oxygenation include decreased exercise tolerance, increased cardiac strain and pulmonary hypertension in addition to pathophysiological involvement of multiple other organs resulting in progressive frailty. Increasing inspired O₂ is expensive, disliked by patients and does not normalise tissue oxygenation; thus, other strategies that improve O₂ delivery and utilisation may provide novel therapeutic opportunities in patients with lung disease. In this review, we focus on the rationale and possibilities for doing this by increasing haemoglobin availability or improving iron regulation.

CFTR Modulator Use Is Associated with Higher Hemoglobin Levels in Individuals with Cystic Fibrosis

RATIONALE

Understanding how cystic fibrosis transmembrane conductance regulator (CFTR) modulators influence comorbid conditions like anemia is of great interest to the cystic fibrosis community.

OBJECTIVES

To test the hypothesis that CFTR modulators are associated with higher hemoglobin (Hgb) levels.

METHODS

Annualized Hgb and other laboratory, demographic, and anthropometric data were abstracted from the U.S. CF Foundation Patient Registry for adult and pediatric registrants before and after therapy with ivacaftor (IVA) or lumacaftor/ivacaftor (LUM/IVA) between January 2010 and December 2016. Univariate and multivariate linear mixed models were used to examine the effect of IVA on Hgb in patients with G551D-CFTR, and the effect of LUM/IVA on Hgb in F508del-CFTR homozygotes. Linear regression was used to characterize change in mean Hgb over time.

RESULTS

A total of 1,347 registrants (707 males and 640 females) with G551D-CFTR and 12,582 F508del-CFTR homozygotes (6,640 males and 5,942 females) who had never undergone lung transplant and had contemporaneous data regarding Hgb and CFTR modulator use were identified. IVA was associated with average Hgb increases of 0.54 gm/dl (95% confidence interval [CI], 0.39-0.69; P < 0.0001) and 0.18 gm/dl (95% CI, 0.01-0.35; P = 0.037) for males and females, respectively, with G551D-CFTR. LUM/IVA was associated with average Hgb increases of 0.58 gm/dl (95% CI, 0.48-0.68; P < 0.0001) and 0.26 gm/dl (95% CI, 0.20-0.33; P < 0.0001) for male and female F508del-CFTR homozygotes, respectively. In multivariate models, IVA positively affected Hgb in males but not females, and LUM/IVA positively affected Hgb in both sexes.

CONCLUSIONS

IVA and LUM/IVA use are both associated with higher Hgb levels in patients with CF.

Red blood cell distribution width is not a reliable biomarker for low iron stores in children with cystic fibrosis

Low iron stores in children, absolute iron deficiency (AID), can lead to impaired neurodevelopment and requires iron therapy. In the presence of infection/inflammation, like in cystic fibrosis (CF), serum ferritin (SF) is not a reliable biomarker for AID. Red blood cell distribution width (RDW) is a promising alternative reported not to be influenced by infection in healthy children. Currently, there are no data on the diagnostic capacity of RDW to detect AID in pediatric CF patients. This was a prospective observational study that investigated iron status biomarkers in 53 Dutch pediatric CF patients. AID was defined using World Health Organization criteria for SF in stable patients (no recent pulmonary exacerbation) and C-reactive protein (CRP) ≤10 mg/l. Patients with AID had higher RDW levels than patients without AID (p = 0.019). An RDW ≥13.2% showed the following test statistics: sensitivity 100%; specificity 39.4%; positive predictive value 20%; and negative predictive value 100%. Furthermore, we found a correlation between RDW and CRP in the total group that originated from the stable patients (r = 0.308; p = 0.042). In conclusion, the diagnostic capacity of RDW for detecting AID in pediatric CF patients seems limited because RDW levels might also be influenced by chronic infection/inflammation in these patients.

Exercise oxidative skeletal muscle metabolism in adolescents with cystic fibrosis

NEW FINDINGS

What is the central question of this study? Do intrinsic abnormalities in oxygenation and/or muscle oxidative metabolism contribute to exercise intolerance in adolescents with mild cystic fibrosis? What is the main finding and its importance? This study found no evidence that in adolescents with mild cystic fibrosis in a stable clinical state intrinsic abnormalities in skeletal muscle oxidative metabolism seem to play a clinical significant role. Based on these results, we concluded that there is no metabolic constraint to benefit from exercise training. Patients with cystic fibrosis (CF) are reported to have limited exercise capacity. There is no consensus about a possible abnormality in skeletal muscle oxidative metabolism in CF. Our aim was to test the hypothesis that abnormalities in oxygenation and/or muscle oxidative metabolism contribute to exercise intolerance in adolescents with mild CF. Ten adolescents with CF (12-18 years of age; forced expiratory volume in 1 s >80% of predicted; and resting oxygen saturation >94%) and 10 healthy age-matched control (HC) subjects were tested with supine cycle ergometry using near-infrared spectroscopy and (31)P magnetic resonance spectroscopy to study skeletal muscle oxygenation and oxidative metabolism during rest, exercise and recovery. No statistically significant (P > 0.1) differences in peak workload and peak oxygen uptake per kilogram lean body mass were found between CF and HC subjects. No differences were found between CF and HC subjects in bulk changes of quadriceps phosphocreatine (P = 0.550) and inorganic phosphate (P = 0.896) content and pH (P = 0.512) during symptom-limited exercise. Furthermore, we found statistically identical kinetics for phosphocreatine resynthesis during recovery for CF and HC subjects (P = 0.53). No statistically significant difference in peak exercise arbitrary units for total haemoglobin content was found between CF and HC subjects (P = 0.66). The results of this study provide evidence that in patients with mild CF and a stable clinical status (without signs of systemic inflammation and/or chronic Pseudomonas aeruginosa colonization), no intrinsic metabolic constraints and/or abnormalities in oxygenation and/or muscle oxidative metabolism contribute to exercise intolerance.

ESPEN-ESPGHAN-ECFS guidelines on nutrition care for infants, children, and adults with cystic fibrosis

BACKGROUND

Malnutrition is both a frequent feature and a comorbidity of cystic fibrosis (CF), with nutritional status strongly associated with pulmonary function and survival. Nutritional management is therefore standard of care in CF patients. ESPEN, ESPGHAN and ECFS recommended guidelines to cover nutritional management of patients with CF.

METHODS

The guidelines were developed by an international multidisciplinary working group in accordance with officially accepted standards. The GRADE system was used for determining grades of evidence and strength of recommendation. Statements were discussed, submitted to Delphi rounds, reviewed by ESPGHAN and ECFS and accepted in an online survey among ESPEN members.

RESULTS

The Working Group recommends that initiation of nutritional management should begin as early as possible after diagnosis, with subsequent regular follow up and patient/family education. Exclusive breast feeding is recommended but if not possible a regular formula is to be used. Energy intake should be adapted to achieve normal weight and height for age. When indicated, pancreatic enzyme and fat soluble vitamin treatment should be introduced early and monitored regularly. Pancreatic sufficient patients should have an annual assessment including fecal pancreatic elastase measurement. Sodium supplementation is recommended and a urinary sodium:creatinine ratio should be measured, corresponding to the fractional excretion of sodium. If iron deficiency is suspected, the underlying inflammation should be addressed. Glucose tolerance testing should be introduced at 10 years of age. Bone mineral density examination should be performed from age 8-10 years. Oral nutritional supplements followed by polymeric enteral tube feeding are recommended when growth or nutritional status is impaired. Zinc supplementation may be considered according to the clinical situation. Further studies are required before essential fatty acids, anti-osteoporotic agents, growth hormone, appetite stimulants and probiotics can be recommended.

CONCLUSION

Nutritional care and support should be an integral part of management of CF. Obtaining a normal growth pattern in children and maintaining an adequate nutritional status in adults are major goals of multidisciplinary cystic fibrosis centers.

A cross-sectional study of the prevalence and associations of iron deficiency in a cohort of patients with chronic obstructive pulmonary disease

OBJECTIVES

Chronic obstructive pulmonary disease (COPD) is a major cause of morbidity and mortality. Iron deficiency, with or without anaemia, is associated with other chronic conditions, such as congestive heart failure, where it predicts a worse outcome. However, the prevalence of iron deficiency in COPD is unknown. This observational study aimed to determine the prevalence of iron deficiency in COPD and associations with differences in clinical phenotype.

SETTING

University hospital outpatient clinic.

PARTICIPANTS

113 adult patients (65% male) with COPD diagnosed according to GOLD criteria (forced expiratory volume in 1 s (FEV1): forced vital capacity (FVC) ratio <0·70 and FEV1 <80% predicted); with age-matched and sex-matched control group consisting of 57 healthy individuals.

MAIN OUTCOME MEASURES

Prevalence of iron deficiency, defined as: any one or more of (1) soluble transferrin receptor >28.1 nmol/L; (2) transferrin saturation <16% and (3) ferritin <12 µg/L. Severity of hypoxaemia, including resting peripheral arterial oxygen saturation (SpO2) and nocturnal oximetry; C reactive protein (CRP); FEV1; self-reported exacerbation rate and Shuttle Walk Test performance.

RESULTS

Iron deficiency was more common in patients with COPD (18%) compared with controls (5%). In the COPD cohort, CRP was higher in patients with iron deficiency (median 10.5 vs 4.0 mg/L, p<0.001), who were also more hypoxaemic than their iron-replete counterparts (median resting SpO2 92% vs 95%, p<0.001), but haemoglobin concentration did not differ. Patients with iron deficiency had more self-reported exacerbations and a trend towards worse exercise tolerance.

CONCLUSIONS

Non-anaemic iron deficiency is common in COPD and appears to be driven by inflammation. Iron deficiency associates with hypoxaemia, an excess of exacerbations and, possibly, worse exercise tolerance, all markers of poor prognosis. Given that it has been shown to be beneficial in other chronic diseases, intravenous iron therapy should be explored as a novel therapeutic option in COPD.

Inflammation, oxidative stress, and cardiovascular disease risk factors in adults with cystic fibrosis

Cystic fibrosis (CF) represents one of a number of localized lung and non-lung diseases with an intense chronic inflammatory component associated with evidence of systemic oxidative stress. Many of these chronic inflammatory diseases are accompanied by an array of atherosclerotic processes and cardiovascular disease (CVD), another condition strongly related to inflammation and oxidative stress. As a consequence of a dramatic increase in long-lived patients with CF in recent decades, the specter of CVD must be considered in these patients who are now reaching middle age and beyond. Buttressed by recent data documenting that CF patients exhibit evidence of endothelial dysfunction, a recognized precursor of atherosclerosis and CVD, the spectrum of risk factors for CVD in CF is reviewed here. Epidemiological data further characterizing the presence and extent of atherogenic processes in CF patients would seem important to obtain. Such studies should further inform and offer mechanistic insights into how other chronic inflammatory diseases potentiate the processes leading to CVDs.

Hemoglobin oxygen affinity in patients with cystic fibrosis

In patients with cystic fibrosis lung damages cause arterial hypoxia. As a typical compensatory reaction one might expect changes in oxygen affinity of hemoglobin. Therefore position (standard half saturation pressure P₅₀st) and slope (Hill’s n) of the O₂ dissociation curve as well as the Bohr coefficients (BC) for CO₂ and lactic acid were determined in blood of 14 adult patients (8 males, 6 females) and 14 healthy controls (6 males, 8 females). While Hill’s n amounted to approximately 2.6 in all subjects, P₅₀st was slightly increased by 1mmHg in both patient groups (controls male 26.7±0.2, controls female 27.0±0.1, patients male 27.7±0.5, patients female 28.0±0.3 mmHg; mean and standard error, overall p<0.01). Main cause was a rise of 1–2 µmol/g hemoglobin in erythrocytic 2,3-biphosphoglycerate concentration. One patient only, clearly identified as an outlier and with the mutation G551D, showed a reduction of both P₅₀st (24.5 mmHg) and [2,3-biphosphoglycerate] (9.8 µmol/g hemoglobin). There were no differences in BCCO₂, but small sex differences in the BC for lactic acid in the controls which were not detectable in the patients. Causes for the right shift of the O₂ dissociation curve might be hypoxic stimulation of erythrocytic glycolysis and an increased red cell turnover both causing increased [2,3-biphosphoglycerate]. However, for situations with additional hypercapnia as observed in exercising patients a left shift seems to be a more favourable adaptation in cystic fibrosis. Additionally when in vivo PO₂ values were corrected to the standard conditions they mostly lay left of the in vitro O₂ dissociation curve in both patients and controls. This hints to unknown fugitive factors influencing oxygen affinity.

Iron deficiency occurs frequently in children with cystic fibrosis

In adult CF patients iron deficiency (ID) is common and primarily functional due to chronic inflammation. No recent data are available on the cause of ID and iron deficiency anemia (IDA) in children with CF. Over the last decades onset of inflammation and pulmonary disease in children with CF is delayed by improved nutritional status. We questioned whether ID occurs in the same extent among children with CF as in adult CF patients. We therefore conducted a study to investigate the iron status of children with CF and to determine whether ID and IDA are associated with dietary iron intake, lung disease severity and Pseudomonas aeruginosa (PA) infection. Clinical charts of 53 children with CF aged 0-16 were reviewed. Follow-up varied from 1 to 14 years with 343 annual observations in total. Thirty-two children (60.4%) were iron deficient in at least 1 year and ID was present in 84 of 343 observations (24.5%). In 2011 ID was present in 9 children (17.0%). Ten children (18.9%) were anemic in at least 1 year and anemia was present in 13 of 328 observations (4.0%). IDA was present in at least 1 year in 6 children (11.3%). Ferritin (Fer) was positively associated with age. Higher Fer values found in older children represent an increased state of inflammation, rather than an improved iron status, and might increase the relative contribution of functional ID. This study shows that ID is common in relatively healthy, well-nourished children with CF. The mechanism of ID in children with CF is currently unknown. A prospective study using both soluble transferrin receptor and Fer as indicators for ID will provide more insight in the incidence and causes of ID in children with CF.

The clinical significance of the gut microbiota in cystic fibrosis and the potential for dietary therapies

Cystic fibrosis (CF) is characterised by many comorbidities related to aberrant mucosa and chronic inflammation in the respiratory and digestive systems. The intestinal mucosa serves as the primary interface between the gut microbiota and endocrine, neural and immune systems. There is emerging evidence that aberrant intestinal mucosa in CF may associate with an altered gut microbiota. Compared to healthy subjects, the overall bacterial abundance and species richness seems to be reduced in CF, accompanied by a trend in suppression of Firmicutes and Bacteroidetes spp. and an augmentation of potentially pathogenic species. There is also some concordance of gut and respiratory microbiotas in CF infants over time. The clinical significance of these observations awaits investigation. The gut microbiota have some potential in CF management by affecting inflammatory and immune responses, and influencing aberrant mucosa. As an important modifiable factor, diet therapies such as probiotics and prebiotics have shown initial promise in improving CF related conditions associated with chronic inflammation. More studies are needed to confirm this, as well as the efficacy of other dietary strategies such as modulating dietary fat and indigestible carbohydrate. Similarly, dietary modification of gut microbiota to optimise nutritional status in CF may be feasible, although more CF-specific studies are warranted.

Anemia and iron deficiency in COPD patients: prevalence and the effects of correction of the anemia with erythropoiesis stimulating agents and intravenous iron

BACKGROUND

Little is known about iron deficiency (ID) and anemia in Chronic Obstructive Pulmonary Disease (COPD). The purposes of this study were: (i) To study the prevalence and treatment of anemia and ID in patients hospitalized with an exacerbation of COPD. (ii) to study the hematological responses and degree of dyspnea before and after correction of anemia with subcutaneous Erythropoiesis Stimulating Agents (ESAs) and intravenous (IV) iron therapy, in ambulatory anemic patients with both COPD and chronic kidney disease.

METHODS

(i) We examined the hospital records of all patients with an acute exacerbation of COPD (AECOPD) to assess the investigation, prevalence, and treatment of anemia and ID. (ii) We treated 12 anemic COPD outpatients with the combination of ESAs and IV-iron, given once weekly for 5 weeks. One week later we measured the hematological response and the severity of dyspnea by Visual Analogue Scale (VAS).

RESULTS

(i) Anemia and iron deficiency in hospitalized COPD patients: Of 107 consecutive patients hospitalized with an AECOPD, 47 (43.9%) were found to be anemic on admission. Two (3.3%) of the 60 non-anemic patients and 18 (38.3%) of the 47 anemic patients had serum iron, percent transferrin saturation (%Tsat) and serum ferritin measured. All 18 (100%) anemic patients had ID, yet none had oral or IV iron subscribed before or during hospitalization, or at discharge. (ii) Intervention outpatient study: ID was found in 11 (91.7%) of the 12 anemic ambulatory patients. Hemoglobin (Hb), Hematocrit (Hct) and the VAS scale scores increased significantly with the ESAs and IV-iron treatment. There was a highly significant correlation between the ∆Hb and ∆VAS; rs = 0.71 p = 0.009 and between the ∆Hct and ∆VAS; rs = 0.8 p = 0.0014.

CONCLUSIONS

ID is common in COPD patients but is rarely looked for or treated. Yet correction of the ID in COPD patients with ESAs and IV iron can improve the anemia, the ID, and may improve the dyspnea.

Iron-regulated expression of alginate production, mucoid phenotype, and biofilm formation by Pseudomonas aeruginosa

Pseudomonas aeruginosa strains of non-cystic fibrosis (non-CF) origin do not produce significant amounts of extracellular alginate and are nonmucoid. In CF, such isolates can become mucoid through mutation of one of the genes (mucA, mucB, mucC, or mucD) that produce regulatory factors that sequester AlgU, required for increased expression of alginate genes. Mutation of the muc genes in the nonmucoid PAO1, PA14, PAKS-1, and Ps388 strains led to increased levels of extracellular alginate and an obvious mucoid phenotype, but only under iron-limiting growth conditions (≤5 µM), not under iron-replete conditions (≥10 µM). In contrast, >50% of P. aeruginosa isolates from chronic CF pulmonary infections expressed increased levels of alginate and mucoidy both under iron-limiting and iron-replete conditions (i.e., iron-constitutive phenotype). No single iron regulatory factor (e.g., Fur, PvdS) was associated with this loss of iron-regulated alginate expression and mucoidy in these CF isolates. However, the loss of only pyoverdine production, or its uptake, abrogated the ability of P. aeruginosa to produce a robust biofilm that represents the Psl-type of biofilm. In contrast, we show that mutation of the pyoverdine and pyochelin biosynthesis genes and the pyoverdine receptor (FpvA) lead to iron-constitutive expression of the key alginate biosynthesis gene, algD, and an explicitly mucoid phenotype in both iron-limiting and iron-replete conditions. These data indicate that alginate production and mucoidy, in contrast to other types of biofilms produced by P. aeruginosa, are substantially enhanced under iron limitation. These results also have compelling implications in relation to the use of iron chelators in the treatment of P. aeruginosa CF infections.

IMPORTANCE

Pseudomonas aeruginosa is a leading model for the investigation of biofilms. While data have been generated about the role of iron in alginate-independent (Psl/Pel) biofilm development, there is a paucity of data regarding the role of iron in alginate production and its associated mucoid phenotype. We demonstrate that biologically relevant levels of iron that exist in the airway mucus of cystic fibrosis (CF) patients have a substantial influence on production of alginate and the overt mucoid phenotype, pathognomonic of P. aeruginosa infections in CF. Mucoid mutants of non-CF P. aeruginosa isolates are mucoid only under iron limitation and do not express increased levels of alginate under iron-replete growth conditions. However, a significant number of long-term CF isolates lost their iron-regulated expression of increased alginate production and mucoidy and became iron constitutive for these properties. In contrast to the formation of Psl-type biofilms, increasing iron limitation ultimately leads to an iron-constitutive expression of alginate and mucoidy.

Iron supplementation does not worsen respiratory health or alter the sputum microbiome in cystic fibrosis

BACKGROUND

Iron supplementation for hypoferremic anemia could potentiate bacterial growth in the cystic fibrosis (CF) lung, but clinical trials testing this hypothesis are lacking.

METHODS

Twenty-two adults with CF and hypoferremic anemia participated in a randomized, double-blind, placebo-controlled, crossover trial of ferrous sulfate 325mg daily for 6weeks. Iron-related hematologic parameters, anthropometric data, sputum iron, Akron Pulmonary Exacerbation Score (PES), and the sputum microbiome were serially assessed. Fixed-effect models were used to describe how ferrous sulfate affected these variables.

RESULTS

Ferrous sulfate increased serum iron by 22.3% and transferrin saturation (TSAT) by 26.8% from baseline (p<0.05) but did not affect hemoglobin, sputum iron, Akron PES, and the sputum microbiome.

CONCLUSIONS

Low-dose ferrous sulfate improved hypoferremia without correcting anemia after 6weeks. We did not observe significant effects on sputum iron, Akron PES, and the sputum microbiome. Although we did not identify untoward health effects of iron supplementation, a larger blinded randomized controlled trial would be needed to fully demonstrate safety.

CFTR is involved in the fine tuning of intracellular redox status: physiological implications in cystic fibrosis

Adaptation to hypoxia is an essential physiological response to decrease in tissue oxygenation. This process is primarily under the control of transcriptional activator hypoxia-inducible factor (HIF1). A better understanding of the intracellular HIF1 stabilization pathway would help in management of various diseases characterized by anemia. Among human pathologies, cystic fibrosis disease is characterized by a chronic anemia that is inadequately compensated by the classical erythroid response mediated by the HIF pathway. Because the kidney expresses CFTR and is a master organ involved in the adaptation to hypoxia, we used renal cells to explore the relationship between CFTR and the HIF1-mediated pathway. To monitor the adaptive response to hypoxia, we engineered a hypoxia-induced fluorescent reporter system to determine whether CFTR modulates hypoxia-induced HIF1 stabilization. We show that CFTR is a regulator of HIF stabilization by controlling the intracellular reactive oxygen species (ROS) level through its ability to transport glutathione (a ROS scavenger) out of the cell. Moreover, we demonstrated in a mouse model that both the pharmacological inhibition and the ΔF508 mutation of CFTR lead to an impairment of the adaptive erythroid response to oxygen deprivation. We conclude that CFTR controls HIF stabilization through control of the level of intracellular ROS that act as signaling agents in the HIF-1 pathway.

Lactoferrin Decreases Inflammatory Response by Cystic Fibrosis Bronchial Cells Invaded with Burkholderia Cenocepacia Iron-Modulated Biofilm

In cystic fibrosis (CF) high iron concentration in airway secretion plays a pivotal role in bacterial multiplication and biofilm formation as well as in inflammatory response. Burkholderia cenocepacia, an opportunistic facultative pathogen responsible for chronic lung infections and cepacia syndrome, recurrently infects CF patients. Lactoferrin (Lf), an iron binding multifunctional glycoprotein synthesized by exocrine glands and neutrophils, has been found at higher concentration in the airway secretions of infected CF patients than in healthy subjects. Here the influence of milk derivative bovine lactoferrin (bLf), an emerging important regulator of iron and inflammatory homeostasis, on invasiveness of B. cenocepacia iron-modulated biofilm, as well as on inflammatory response by infected CF bronchial (IB3-1) cells, is reported, bLf did not significantly affect invasion efficacy by biofilm-forming B. cenocepacia clinical strains. Conversely, the addition of bLf to cell monolayers during infection significantly decreased the pro-inflammatory Interleukin (IL)-1β and increased the antiinflammatory IL-11 expression compared to that observed in cells infected in the absence of bLf. The bLf ability to modulate genes expressed following B. cenocepacia infection seems related to its localization to the nucleus of infected IB3-1 cells. These results provide evidence for a role of bLf in the protection of infected CF cells from inflammation-related damage, thus extending the therapeutic potential of this multifunctional natural protein.

Iron and CF-related anemia: expanding clinical and biochemical relationships

INTRODUCTION

This cross-sectional study was conducted to assess the relationship between iron levels in the plasma and sputum of cystic fibrosis (CF) patients.

METHODS

Demographic, clinical, and iron-related laboratory data were prospectively obtained from 25 patients with stable clinical features and 14 patients with worsened clinical features since their most recent evaluations.

RESULTS

Compared to patients with stable clinical features, those who experienced clinical deterioration demonstrated significantly worse lung function and were more frequently malnourished and diabetic. Members of the latter group were also significantly more hypoferremic and had higher sputum iron content than patients with stable clinical features. No significant correlation was found between plasma and sputum iron levels when the groups were analyzed together and separately.

CONCLUSIONS

Sputum iron content does not correlate with iron-related hematologic tests. Hypoferremia is common in CF and correlates with poor lung function and overall health.

Skeletal muscle metabolism in cystic fibrosis and primary ciliary dyskinesia

Previous studies have reported differences in muscle function and metabolism between patients with cystic fibrosis (CF) and healthy controls (HC), but it is currently unknown whether these abnormalities are specific to CF or also seen in other airway diseases. In this study, we used magnetic resonance spectroscopy (MRS) during exercise to assess muscle metabolism in CF patients. Twenty patients with CF and 20 age, gender, and habitual activity-matched HCs and a respiratory disease comparison group with primary ciliary dyskinesia (PCD; n = 10) were studied. Phosphorus MRS (P-MRS) was used to characterize muscle bioenergetic metabolism at rest and after high-, moderate-, and low-intensity exercise. CF patients exhibited lower resting ATP/phosphocreatine (PCr) ratio and significantly higher end-exercise pH values compared with both HC and PCD patients. Both CF and PCD patients demonstrated significantly slower PCr recovery time constants after high-intensity exercise. Our results suggest that not only there are specific abnormalities of muscle metabolism in CF patients but also there is a nonspecific impact of respiratory disease on muscle function.

Proton secretion in freshly excised sinonasal mucosa from asthma and sinusitis patients

BACKGROUND

Proton (H+) secretion and the HVCN1 H+ channel are part of the innate host defense mechanism of the airways. The objective of this study was to determine H+ secretion in asthmatic and nonasthmatic patients with chronic rhinosinusitis (CRS) in freshly excised human sinonasal tissue.

METHODS

Nasal or sinus mucosa from subjects with three different conditions (normal, CRS, and CRS with asthma) was harvested during sinus surgery. The equilibrium pH and the rate of H+ secretion were measured in an Ussing chamber using the pH-stat titration technique.

RESULTS

Nasal epithelia isolated from subjects with CRS and asthma had a mucosal equilibrium pH = 6.95 (n = 5), which was significantly lower than in normal subjects (7.35 +/- 0.21; n = 5) or from subjects with CRS without asthma (7.33 +/- 0.15 In = 5). Nasal epithelia from CRS with asthma (n = 5) secreted H+ at a rate of 135 +/- 46 nmol x min(-1) x cm(-2). This rate was significantly higher compared with normal (73 +/- 39 nmol x min(-1) x cm(-2); n = 8) or CRS without asthma (51 +/- 28 nmol x min(-1) x cm(-2); n = 7). Mucosal addition of the HVCN1 blocker ZnCl2 blocked H+ secretion by 70% in normal, 53% in CRS without asthma, and by 51% in CRS with asthma. In contrast, measures in sinus tissues were unaffected by the disease condition.

CONCLUSION

Freshly excised human nasal and sinus epithelia secrete acid. Nasal (but not sinus) tissues from asthmatic CRS patients showed lower mucosal pH values and higher rates of H+ secretion than CRS and normal subjects. The increased acid secretion might contribute to epithelial injury in CRS patients with asthma.

Nutrition management of pediatric patients who have cystic fibrosis

Since the identification of cystic fibrosis (CF) in the 1940s, nutrition care of patients who have CF has been a challenge. Through optimal caloric intake and careful management of malabsorption, patients are expected to meet genetic potential for growth. Yet factors beyond malabsorption, including nutrient activity at the cellular level, may influence growth and health. This article reviews nutrition topics frequently discussed in relationship to CF and presents intriguing new information describing nutrients currently being studied for their impact on overall health of patients who have CF.

Tobramycin and FDA-approved iron chelators eliminate Pseudomonas aeruginosa biofilms on cystic fibrosis cells

The ability of Pseudomonas aeruginosa to form antibiotic-resistant biofilms is thought to account for the inability of current therapies to resolve bacterial infections in the lungs of patients with cystic fibrosis (CF). We recently described a system in which highly antibiotic-resistant P. aeruginosa biofilms grow on human CF airway epithelial cells, and using this system we showed that enhanced iron release from CF cells facilitates the development of such highly antibiotic-resistant biofilms. Given the positive role for iron in biofilm development, we investigated whether the FDA-approved iron chelators deferoxamine and deferasirox would enhance the ability of tobramycin, the primary antibiotic used to treat CF lung infections, to eliminate P. aeruginosa biofilms. The combination of tobramycin with deferoxamine or deferasirox reduced established biofilm biomass by approximately 90% and reduced viable bacteria by 7-log units. Neither tobramycin nor deferoxamine nor deferasirox alone had such a marked effect. The combination of tobramycin and FDA-approved iron chelators also prevented the formation of biofilms on CF airway cells. These data suggest that the combined use of tobramycin and FDA-approved iron chelators may be an effective therapy to treat patients with CF and other lung disease characterized by antibiotic-resistant P. aeruginosa biofilms.