Plasma zinc in adults with cystic fibrosis: correlations with clinical outcomes

Zinc status in cystic fibrosis patients; a systematic review and meta-analysis

Background

Cystic fibrosis (CF) is an autosomal recessive hereditary disease causes concentration of secretions and this affects the lungs and digestive system. These patients are exposed to zinc (zn) deficiency. In this review, we decided to investigate the status of zn in CF patients compared to control group. Also, the clinical trials that have so far performed zinc supplementation in these patients are examined.

Method

ISI Web of Science, Scopus, PubMed/Medline, and Cochrane database were searched, up to December 2023, for studies that reported the association between zn levels of CF patients compared to a healthy control group. A random-effect model was used to compute the pooled weighted mean difference (WMD) with 95 % confidence intervals (CI). Subgroup analysis was done for region, sample and method of measurement, zinc supplementation and age.

Result

Overall, meta-analysis of 9 studies (n = 383 participants) revealed that the zn levels were significantly lower in children and adolescents with CF compared with healthy subjects (WMD = -11.97 μg/dL, 95 % CI: -22.57 to -1.37; I2 = 92.83 %). Meta-analysis of 8 studies (n = 320 participants) revealed that the serum and plasma level of zn was significantly lower in CF patients compared with healthy subjects (WMD = -14.31 μg/dL, 95 % CI: -25.09 to -3.53; I2 = 88.14 %, P-heterogeneity <0.001) While the zn level in saliva and sputum was significantly higher in CF patients.

Conclusion

CF patients have decreased zn levels in circulatory reservoirs. zn may effective for the diminish the respiratory and gastrointestinal symptoms in CF patients, further well-designed clinical trial studies is required to prove these effects.

The Role of Zinc in Developed Countries in Pediatric Patients: A 360-Degree View

Zinc is an important trace element for growth and health at pediatric ages. Zinc is fundamental in inflammatory pathways, oxidative balance, and immune function. Zinc exhibits anti-inflammatory properties by modulating Nuclear Factor-kappa (NF-κB) activity and reducing histamine release from basophils, leukocytes, and mast cells. Furthermore, its antioxidant activity protects against oxidative damage and chronic diseases. Finally, zinc improves the ability to trigger effective immune responses against pathogens by contributing to the maturation of lymphocytes, the production of cytokines, and the regulation of apoptosis. Given these properties, zinc can be considered an adjunctive therapy in treating and preventing respiratory, nephrological, and gastrointestinal diseases, both acute and chronic. This review aims to deepen the role and metabolism of zinc, focusing on the role of supplementation in developed countries in pediatric diseases.

Changes in vitamins and trace elements after initiation of highly effective CFTR modulator therapy in children and adults with cystic fibrosis - a real-life insight

BACKGROUND

Highly-effective CFTR-modulator therapy with elexa-/teza-/ivacaftor (ETI) has led to improvements in pulmonary outcomes, sweat chloride, body mass index (BMI) and quality of life in people with cystic fibrosis (CF). Improved uptake of fat-soluble vitamins and micronutrients has been reported for CFTR-modulators but data regarding ETI therapy is lacking.

METHODS

This single-center retrospective study evaluated forced expiratory volume in one second (FEV-1), sweat chloride, BMI, transaminases (AST, ALT), bilirubin, vitamins A, D, E, zinc and selenium in children and adults eligible for ETI. Parameters were assessed before and up to one year after initiation of ETI.

RESULTS

58 patients (median age m = 28 years, SD ± 11.6 years, 51.7% female14 < 18 years old) were included. FEV-1 and sweat chloride improved significantly after ETI. There were no changes in BMI or AST. ALT was increased significantly after 4 weeks of ETI but returned to normal levels in further course. Bilirubin levels remained elevated after ETI. Vitamin A was significantly higher 12 months after ETI. No changes were found for vitamins D, E, zinc and selenium.

CONCLUSIONS

This study adds to the evidence that improvements of some fat-soluble vitamin levels can be found after ETI. No changes regarding micronutrients were noted. Individualized follow-up and supplementation are recommended.

CFTR is required for zinc-mediated antibacterial defense in human macrophages

Cystic fibrosis transmembrane conductance regulator (CFTR) is an anion transporter required for epithelial homeostasis in the lung and other organs, with CFTR mutations leading to the autosomal recessive genetic disease CF. Apart from excessive mucus accumulation and dysregulated inflammation in the airways, people with CF (pwCF) exhibit defective innate immune responses and are susceptible to bacterial respiratory pathogens such as Pseudomonas aeruginosa. Here, we investigated the role of CFTR in macrophage antimicrobial responses, including the zinc toxicity response that is used by these innate immune cells against intracellular bacteria. Using both pharmacological approaches, as well as cells derived from pwCF, we show that CFTR is required for uptake and clearance of pathogenic Escherichia coli by CSF-1-derived primary human macrophages. CFTR was also required for E. coli-induced zinc accumulation and zinc vesicle formation in these cells, and E. coli residing in macrophages exhibited reduced zinc stress in the absence of CFTR function. Accordingly, CFTR was essential for reducing the intramacrophage survival of a zinc-sensitive E. coli mutant compared to wild-type E. coli. Ectopic expression of the zinc transporter SLC30A1 or treatment with exogenous zinc was sufficient to restore antimicrobial responses against E. coli in human macrophages. Zinc supplementation also restored bacterial killing in GM-CSF-derived primary human macrophages responding to P. aeruginosa, used as an in vitro macrophage model relevant to CF. Thus, restoration of the zinc toxicity response could be pursued as a therapeutic strategy to restore innate immune function and effective host defense in pwCF.

ESPEN-ESPGHAN-ECFS guideline on nutrition care for cystic fibrosis

BACKGROUND

Nutritional status is paramount in Cystic Fibrosis (CF) and is directly correlated with morbidity and mortality. The first ESPEN-ESPGHAN-ECFS guidelines on nutrition care for infants, children, and adults with CF were published in 2016. An update to these guidelines is presented.

METHODS

The study was developed by an international multidisciplinary working group in accordance with officially accepted standards. Literature since 2016 was reviewed, PICO questions were discussed and the GRADE system was utilized. Statements were discussed and submitted for on-line voting by the Working Group and by all ESPEN members.

RESULTS

The Working Group updated the nutritional guidelines including assessment and management at all ages. Supplementation of vitamins and pancreatic enzymes remains largely the same. There are expanded chapters on pregnancy, CF-related liver disease, and CF-related diabetes, bone disease, nutritional and mineral supplements, and probiotics. There are new chapters on nutrition with highly effective modulator therapies and nutrition after organ transplantation.

Update on the management of vitamins and minerals in cystic fibrosis

Advancements in respiratory and nutrition management have significantly improved the survival of patients with cystic fibrosis (CF). With the availability of several nutrition interventions such as oral/enteral nutrition supplements, enteric‐coated pancreatic enzymes, and water‐miscible CF‐specific vitamin supplements, frank vitamin deficiencies—with the exception of vitamin D—are rarely encountered in current clinical practice. Whereas they were previously considered as micronutrients, our current understanding of fat‐soluble vitamins and minerals as antioxidants, immunomodulators, and disease biomarkers has been evolving. The impact of highly effective modulators on the micronutrient status of patients with CF remains elusive. This narrative review focuses on the updates on the management of fat‐soluble vitamins and other micronutrients in CF in the current era and identifies the gaps in our knowledge.

The Role of Zinc in the Pathogenesis of Lung Disease

Lung diseases, such as asthma, chronic obstructive pulmonary diseases (COPD), and cystic fibrosis (CF), are among the leading causes of mortality and morbidity globally. They contribute to substantial economic burdens on society and individuals. Currently, only a few treatments are available to slow the development and progression of these diseases. Thus, there is an urgent unmet need to develop effective therapies to improve quality of life and limit healthcare costs. An increasing body of clinical and experimental evidence suggests that altered zinc and its regulatory protein levels in the systemic circulation and in the lungs are associated with these disease’s development and progression. Zinc plays a crucial role in human enzyme activity, making it an essential trace element. As a cofactor in metalloenzymes and metalloproteins, zinc involves a wide range of biological processes, such as gene transcription, translation, phagocytosis, and immunoglobulin and cytokine production in both health and disease. Zinc has gained considerable interest in these lung diseases because of its anti-inflammatory, antioxidant, immune, and metabolic modulatory properties. Here we highlight the role and mechanisms of zinc in the pathogenesis of asthma, COPD, CF, acute respiratory distress syndrome, idiopathic pulmonary fibrosis, and pulmonary hypertension.

Nutrition management in adults with cystic fibrosis

Cystic fibrosis (CF) is a lethal, monogenic, autosomal recessive disease with manifestations in multiple organ systems, including the lungs and gastrointestinal tract, that impact adequate nutrition. This review discusses important aspects of nutrition in adults with CF with a focus on exocrine pancreatic insufficiency, CF-related diabetes, and gastrointestinal motility, as well as how advanced lung disease, CF transmembrane conductance regulator modulators, and aging impact nutrition in CF.

Combination of zinc and selenium alleviates ochratoxin A-induced fibrosis via blocking ROS-dependent autophagy in HK-2 cells

BACKGROUND

Ochratoxin A (OTA) is a mycotoxin produced by Aspergillus and Penicillium. The key target organ of OTA toxicity is the kidney, which has a significant impact on human health. Recently, nutrition regulation is suggested to be an effective protection against mycotoxins contamination. The current study investigated the combined protective effects of zinc and selenomethionine (SeMet) (a major component of organic selenium) on OTA-induced renal fibrosis and their potential mechanisms in human renal proximal tubule epithelial cells (HK-2 cells).

METHODS

Cytotoxicity of different concentrations of OTA, zinc and SeMet on HK-2 cells was detected by cell viability, lactate dehydrogenase (LDH) and apoptotic nuclei assays. The expression of fibrosis biomarkers was detected by Real-Time PCR, western blotting and indirect immunofluorescence assays. The production of reactive oxygen species (ROS) was detected by ROS assay kit. The protein expression of autophagy biomarkers was detected by western blotting assay.

RESULTS

Cytotoxicity was induced by OTA treatment in a dose-dependent manner, and it was attenuated by zinc or SeMet application in HK-2 cells. Zinc or SeMet application also down-regulated the expression of fibrosis biomarkers, and the combination of them displayed better effects. In addition, OTA increased intracellular ROS level and activated autophagy in a dose-dependent manner, and it was reversed by zinc and SeMet combined application. With the treatment of hydrogen peroxide (H₂O₂) or rapamycin (the specific activator of autophagy), the combined protective effects of zinc and SeMet were abolished.

CONCLUSIONS

Zinc and SeMet application alleviated OTA-induced cytotoxicity and fibrosis in HK-2 cells. Combination of them was more effective than its individual application. The present study manifest novel insight about the alleviation of OTA-induced nephrotoxicity by nutrition regulation, and had a guiding effect on the clinical supplementation of nutritional elements.

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.

Copper and Copper/Zinc Ratio in a Series of Cystic Fibrosis Patients

Cystic fibrosis (CF) patients require a stable and sufficient supply of micronutrients. Since copper is an essential micronutrient for human development, a cross-sectional study was carried out to investigate the serum copper levels, serum copper/zinc (Cu/Zn) ratios, and their relationship with nutritional indicators in a group of CF patients. Anthropometric, biochemical, and dietary measurements, an abdominal ultrasound, and respiratory and pancreatic tests were conducted. Seventeen CF patients were studied (10 females, 59%), 76.5% of whom were ∆F580. Their mean serum copper (113 ± 23 μg/dL) was normal, and there was only one teenager with hypocupremia (6%) and two children with hypercupremia (18%). A significant association between serum copper and zinc levels was discovered. The Cu/Zn ratio was higher than 1.00 for 94% of patients, which is an indicator of an inflammation status. There was no significant correlation between the serum copper concentrations and respiratory and pancreatic function, respiratory colonization, and the results of the abdominal ultrasound. Linear regression analysis showed that serum copper had a positive association with both the Z-score body mass index (BMI) and mean bone conduction speed (BCS). Therefore, since 94% of CF patients had a Cu/Zn ratio > 1.00, this factor must alert us to consider the risk of zinc deficiency and high inflammatory response. The measurement of serum zinc alone does not show one's zinc status. However, the Cu/Zn ratio may be an indicator of zinc deficiency and the inflammatory status of CF patients.

Zinc Nutritional Status in Patients with Cystic Fibrosis

BACKGROUND

Zinc is an essential nutrient for all forms of life and its deficiency affects the normal growth and development of human beings.

OBJECTIVE

The main aim was to investigate zinc nutritional status by serum zinc concentration (SZC) and dietary zinc intake and their association in cystic fibrosis (CF) patients.

METHODS

A cross-sectional study was conducted in CF patients. Anthropometric measurements and respiratory and pancreatic tests were conducted. Hypozincemia was determined by SZC while using atomic absorption spectrophotometry and dietary zinc deficiency by prospective 72-h dietary surveys.

RESULTS

Mean SZC (87.2 ± 16.7 μg/dL) and dietary zinc intake (97 ± 26.9% Dietary Reference Intake) were normal. Three of 17 patients with CF (17.6%) had hypozincemia and four (23.5%) had a dietary zinc deficiency. No patient with dietary zinc deficiency had hypozincemia. A positive and significant association was observed between SZC and Z-score of BMI-for-age (p = 0.048) and weight-for-height (p = 0.012) and between dietary zinc intake and energy intake (EI, p = 0.036) and Z-score of weight-for-high (p = 0.029).

CONCLUSION

SZC was associated with the nutritional status, expressed as BMI (Body Mass Index) and weight-for-height Z score, and dietary zinc intake with EI and weight-for-height Z-score. No patient with hypozincemia had dietary zinc deficiency. This situation should alert us to a marginal zinc deficiency and it may explain why there were no overlapping cases between the two groups. We suggest that probably 41% of the cases in this study would be at elevated risk of zinc deficiency and a zinc supplementation may be considered.

Zinc Deficiency via a Splice Switch in Zinc Importer ZIP2/SLC39A2 Causes Cystic Fibrosis-Associated MUC5AC Hypersecretion in Airway Epithelial Cells

Airway mucus hyperproduction and fluid imbalance are important hallmarks of cystic fibrosis (CF), the most common life-shortening genetic disorder in Caucasians. Dysregulated expression and/or function of airway ion transporters, including cystic fibrosis transmembrane conductance regulator (CFTR) and epithelial sodium channel (ENaC), have been implicated as causes of CF-associated mucus hypersecretory phenotype. However, the contributory roles of other substances and transporters in the regulation of CF airway pathogenesis remain unelucidated. Here, we identified a novel connection between CFTR/ENaC expression and the intracellular Zn^2 + concentration in the regulation of MUC5AC, a major secreted mucin that is highly expressed in CF airway. CFTR-defective and ENaC-hyperactive airway epithelial cells specifically and highly expressed a unique, alternative splice isoform of the zinc importer ZIP2/SLC39A2 (ΔC-ZIP2), which lacks the C-terminal domain. Importantly, ΔC-ZIP2 levels correlated inversely with wild-type ZIP2 and intracellular Zn^2 + levels. Moreover, the splice switch to ΔC-ZIP2 as well as decreased expression of other ZIPs caused zinc deficiency, which is sufficient for induction of MUC5AC; while ΔC-ZIP2 expression per se induced ENaC expression and function. Thus, our findings demonstrate that the novel splicing switch contributes to CF lung pathology via the novel interplay of CFTR, ENaC, and ZIP2 transporters.

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Zinc deficiency is a common feature in both CFTR-defective (CF) and ENaC-hyperactive (CF-like) airway epithelial cells.

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A splice switch from WT-ZIP2 to ΔC-ZIP2 as well as other ZIPs down-regulation caused zinc deficiency in CF and CF-like cells.

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Lower intracellular Zn^2 + levels contributed to CF-associated MUC5AC hypersecretion in airway epithelial cells.

The role of zinc in the pathogenesis of CF lung disease is not well understood. We utilized human CF patient-derived cell lines and primary cells as well as murine CF model, and identified zinc deficiency as a common characteristic in CF models. Down-regulation of several zinc importers (ZIPs) in CF cells caused zinc deficiency, which is sufficient for induction of MUC5AC, a major secreted mucin that exacerbates CF pathogenesis. Especially, strong contribution of ΔC-ZIP2, a novel ZIP2 splice isoform, in the regulation of CF-associated MUC5AC hypersecretion was clearly demonstrated. The study refined the importance of zinc in airway homeostasis.

High Precision Zinc Stable Isotope Measurement of Certified Biological Reference Materials Using the Double Spike Technique and Multiple Collector-ICP-MS

Biological reference materials with well-characterised stable isotope compositions are lacking in the field of 'isotope biochemistry', which seeks to understand bodily processes that rely on essential metals by determining metal stable isotope ratios. Here, we present Zn stable isotope data for six biological reference materials with certified trace metal concentrations: fish muscle, bovine muscle, pig kidney, human hair, human blood serum and human urine. Replicate analyses of multiple aliquots of each material achieved reproducibilities (2sd) of 0.04-0.13‰ for δ66/64Zn (which denotes the deviation of the 66Zn/64Zn ratio of a sample from a pure Zn reference material in parts per 1000). This implies only very minor isotopic heterogeneities within the samples, rendering them suitable as quality control materials for Zn isotope analyses. This endorsement is reinforced by (i) the close agreement of our Zn isotope data for two of the samples (bovine muscle and human blood serum) to previously published results for different batches of the same material and (ii) the similarity of the isotopic data for the samples (δ66/64Zn ≈ -0.8 to 0.0‰) to previously published Zn isotope results for similar biological materials. Further tests revealed that the applied Zn separation procedure is sufficiently effective to enable accurate data acquisition even at low mass resolving power (M/ΔM ≈ 400), as measurements and analyses conducted at much higher mass resolution (M/ΔM ≈ 8500) delivered essentially identical results.

Serum zinc concentration in cystic fibrosis patients with CFTR I1234V mutation associated with pancreatic sufficiency

OBJECTIVE

To determine serum zinc (Zn) level among cystic fibrosis (CF) patients with homozygous CFTR I1234V mutation associated with pancreatic sufficiency (PS).

METHODS

A cross-sectional study was conducted including both pediatric and adult CF patients. Data on age, weight, height, body mass index (BMI), BMI Z-score, FEV1, and chronic Pseudomonas aeruginosa infection were collected. Serum Zn, albumin, and total proteins were measured and analyzed.

RESULTS

Forty-five CF patients with homozygous CFTR I1234V mutation belonging to a large Arab kindred tribe and eight CF patients with other mutations associated with pancreatic insufficiency (PI). Patient's age ranged from 2 to 49 years with a mean age of 15.1 ± 9.1 years and mean plasma Zn of 0.78 ± 0.15 mcg/mL. Seven (13.2%) patients with CFTR I1234V and PS had low Zn levels (<0.6 mcg/mL). Mean age among Zn deficient group was significantly older. The mean FEV1 in the deficient group was found to be insignificant low. Persistent P. aeruginosa colonization was more prevalent in Zn deficient group. BMI Z-scosre of CF patients were positively correlated with Zn levels. Forty-five healthy subjects belonging to the same Arab tribe were selected in order to assess their Zn levels and their mean plasma Zn of 0.84 ± 0.11 mcg/mL (range 0.65-1.1 mcg/mL) with mean age 20.4 ± 10.1 years (range 6-40 years).

CONCLUSION

These findings suggest that Zn deficiency can occur in CF patients with PS. The association of Zn levels and the frequency of P. aeruginosa isolated in CF patients need further investigation.

Changes in Mineral Micronutrient Status During and After Pulmonary Exacerbation in Adults With Cystic Fibrosis

BACKGROUND

Patients with cystic fibrosis (CF) may be at risk for micronutrient depletion, particularly during periods of illness and infection. The purpose of this study was to investigate serum micronutrient status over time in adults with CF initially hospitalized with a pulmonary exacerbation.

MATERIALS AND METHODS

This was an ancillary study of a multicenter trial investigating the role of high-dose vitamin D supplementation in 24 adults with CF (mean age, 29.6 ± 7.3 years). We measured serum concentrations of copper (Cu), iron (Fe), calcium (Ca), magnesium (Mg), potassium (K), and sulfur (S) in subjects at the beginning of a pulmonary exacerbation and again at 3 months.

RESULTS

Serum concentrations of Cu, Fe, and Ca were significantly lower at baseline compared with 3 months following the pulmonary exacerbation (Cu: baseline, 1.5 ± 0.6 vs 3 months, 1.6 ± 0.6 µg/mL, P = .027; Fe: 0.8 ± 0.3 vs 1.3 ± 1.1 µg/mL, P = .026; Ca: 9.7 ± 0.8 vs 10.8 ± 2.0 mg/dL, P = .024). Serum concentrations of K, Mg, and S did not change over time (K: baseline, 4.9 ± 0.3 vs 3 months, 5.1 ± 0.5 mEq/L; Mg: 1.8 ± 0.2 vs 2.0 ± 0.3 mg/dL; S: 1288.6 ± 343 vs 1309.9 ± 290 µg/mL; P > .05 for all).

CONCLUSION

Serum concentrations of Cu, Fe, and Ca increased significantly several months following recovery from acute pulmonary exacerbation in adults with CF. This may reflect decreased inflammation, improved food intake, and/or increased absorption following recovery.