Iodine deficiency and subclinical hypothyroidism are common in cystic fibrosis patients

Auxological and Endocrinological Features in Children and Adolescents with Cystic Fibrosis

Cystic fibrosis (CF) is a multisystem autosomal recessive disease caused by mutations that lead to deficient or dysfunctional CF transmembrane conductance regulator (CFTR) proteins. Patients typically present malnutrition resulting from the malabsorption of fundamental nutrients and recurring lung infections, with a progressive worsening of the respiratory function. For these reasons, the clinical management of CF requires a multidisciplinary team. From an endocrinological point of view, patients often present major complications, such as diabetes, bone disease, thyroid disorders, delayed growth and puberty, hypogonadism and infertility, which negatively affect their quality of life and, in some cases, significantly reduce life expectancy. These complications can arise as a direct result of CFTR dysfunction and/or as a consequence of a deterioration in the function of the organs affected. The objective of this review is to analyze all the possible endocrinological complications that can occur in patients with CF by evaluating the most recent papers in the literature.

17β-Estradiol activates Cl- channels via the estrogen receptor α pathway in human thyroid cells

Estradiol regulates thyroid function, and chloride channels are involved in the regulation of thyroid function. However, little is known about the role of chloride channels in the regulation of thyroid functions by estrogen. In this study, the effects of estrogen on chloride channel activities in human thyroid Nthy-ori3-1 cells were therefore investigated using the whole cell patch-clamp technique. The results showed that the extracellular application of 17β-estradiol (E2) activated Cl⁻ currents, which reversed at a potential close to Cl⁻ equilibrium potential and showed remarkable outward rectification and an anion permeability of I⁻ > Br⁻ > Cl⁻ > gluconate. The Cl⁻ currents were inhibited by the chloride channel blockers, NPPB and tamoxifen. Quantitative Real-time PCR results demonstrated that ClC-3 expression was highest in ClC family member in Nthy-ori3-1 cells. The down-regulation of ClC-3 expression by ClC-3 siRNA inhibited E2-induced Cl⁻ current. The Cl⁻ current was blocked by the estrogen receptor antagonist, ICI 182780 (fulvestrant). Estrogen receptor alpha (ERα) and not estrogen receptor beta was the protein expressed in Nthy-ori3-1 cells, and the knockdown of ERα expression with ERα siRNA abolished E2-induced Cl⁻ currents. Estradiol can promote the accumulation of ClC-3 in cell membrane. ERα and ClC-3 proteins were partially co-localized in the cell membrane of Nthy-ori3-1 cells after estrogen exposure. The results suggest that estrogen activates chloride channels via ERα in normal human thyroid cells, and ClC-3 proteins play a pivotal role in the activation of E2-induced Cl⁻ current.

Molecular functions and clinical impact of thyroid hormone-triggered autophagy in liver-related diseases

The liver is controlled by several metabolic hormones, including thyroid hormone, and characteristically displays high lysosomal activity as well as metabolic stress-triggered autophagy, which is stringently regulated by the levels of hormones and metabolites. Hepatic autophagy provides energy through catabolism of glucose, amino acids and free fatty acids for starved cells, facilitating the generation of new macromolecules and maintenance of the quantity and quality of cellular organelles, such as mitochondria. Dysregulation of autophagy and defective mitochondrial homeostasis contribute to hepatocyte injury and liver-related diseases, such as non-alcoholic fatty liver disease (NAFLD) and liver cancer.

Thyroid hormones (TH) mediate several critical physiological processes including organ development, cell differentiation, metabolism and cell growth and maintenance. Accumulating evidence has revealed dysregulation of cellular TH activity as the underlying cause of several liver-related diseases, including alcoholic or non-alcoholic fatty liver disease and liver cancer. Data from epidemiologic, animal and clinical studies collectively support preventive functions of THs in liver-related diseases, highlighting the therapeutic potential of TH analogs. Elucidation of the molecular mechanisms and downstream targets of TH should thus facilitate the development of therapeutic strategies for a number of major public health issues.

Here, we have reviewed recent studies focusing on the involvement of THs in hepatic homeostasis through induction of autophagy and their implications in liver-related diseases. Additionally, the potential underlying molecular pathways and therapeutic applications of THs in NAFLD and HCC are discussed.

Investigation of adrenal and thyroid gland dysfunction in dogs with ultrasonographic diagnosis of gallbladder mucocele formation

Gallbladder mucocele formation is an emerging disease in dogs characterized by increased secretion of condensed granules of gel-forming mucin by the gallbladder epithelium and formation of an abnormally thick mucus that can culminate in obstruction of the bile duct or rupture of the gallbladder. The disease is associated with a high morbidity and mortality and its pathogenesis is unknown. Affected dogs have a significantly increased likelihood of concurrent diagnosis of hyperadrenocorticism, hypothyroidism, and hyperlipidemia. Whether these endocrinopathies represent coincidental primary disease processes that exacerbate gallbladder mucocele formation in predisposed dogs or reflect a concurrent disruption of endocrine and lipid metabolism is unclear. In this study, we investigated a hypothesis that dogs with gallbladder mucocele formation would have a high prevalence of occult and atypical abnormalities in adrenal cortical and thyroid gland function that would suggest the presence of endocrine disruption and provide deeper insight into disease pathogenesis. We performed a case-control study of dogs with and without ultrasonographic diagnosis of gallbladder mucocele formation and profiled adrenal cortical function using a quantitative mass spectrometry-based assay of serum adrenal-origin steroids before and after administration of synthetic cosyntropin. We simultaneously profiled serum thyroid hormone concentrations and evaluated iodine sufficiency by measurement of urine iodine:creatinine ratios (UICR). The studies were complemented by histological examination of archival thyroid tissue and measurements of thyroid gland organic iodine from dogs with gallbladder mucocele formation and control dogs. Dogs with gallbladder mucocele formation demonstrated an exaggerated cortisol response to adrenal stimulation with cosyntropin. A prevalence of 10% of dogs with gallbladder mucocele formation met laboratory-based criteria for suspect or definitive diagnosis of hyperadrenocorticism. A significantly greater number of dogs with gallbladder mucocele formation had basal serum dehydroepiandrosterone (DHEAS) increases compared to control dogs. A high percentage of dogs with gallbladder mucocele formation (26%) met laboratory-based criteria for diagnosis of hypothyroidism, but lacked detection of anti-thyroglobulin antibodies. Dogs with gallbladder mucocele formation had significantly higher UICRs than control dogs. Examination of thyroid tissue from an unrelated group of dogs with gallbladder mucocele formation did not demonstrate histological evidence of thyroiditis or significant differences in content of organic iodine. These findings suggest that dogs with gallbladder mucocele formation have a greater capacity for cortisol synthesis and pinpoint DHEAS elevations as a potential clue to the underlying pathogenesis of the disease. A high prevalence of thyroid dysfunction with absent evidence for autoimmune thyroiditis suggest a disrupted thyroid hormone metabolism in dogs with gallbladder mucocele formation although an influence of non-thyroidal illness cannot be excluded. High UICR in dogs with gallbladder mucocele formation is of undetermined significance, but of interest for further study.

Hyperthyrotropinemia in newly diagnosed cystic fibrosis patients with pancreatic insufficiency reversed by enzyme therapy

Patients with cystic fibrosis (CF) commonly present with an elevated TSH concentration, suggesting subclinical hypothyroidism. Its relation to concomitant pancreatic insufficiency and its natural course upon initiation of enzyme replacement have not been adequately studied. Herein, we investigated the thyroid function in newly diagnosed infants with CF and monitored the course of thyroid function response to pancreatic enzyme substitution treatment. Fourteen, newly diagnosed infants with CF and pancreatic insufficiency, were followed every 6-8 weeks for 6 months ensuing onset of pancreatic enzyme substitution therapy. All infants had normal TSH values on neonatal screening. Ten out of 14 (71%) had hyperthyrotropinemia and normal freeT4 values at presentation. No patient received thyroxine. Upon follow-up, after 6 months, TSH values normalized in 90% of infants with CF and hyperthyrotropinemia. Serum selenium levels were negatively correlated with TSH levels.

CONCLUSION

Mild TSH elevation is a frequent finding in newly diagnosed cystic fibrosis patients with pancreatic insufficiency during infancy. TSH elevation resolves in most cases after initiation of enzyme substitution and improvement of nutritional status without any substitutive therapy with thyroxine. What is Known: • Newly diagnosed infants with cystic fibrosis often present with a state of hyperthyrotropinemia suggesting subclinical hypothyroidism. What is New: • Pancreatic enzyme substitution and improvement of nutrition restores normal TSH levels without the need of thyroxine therapy.

Thyroid hormone inhibits growth of hepatoma cells through induction of miR-214

Thyroid hormone (TH) plays a role in regulating the metabolic rate, heart functions, muscle control and maintenance of bones. 3,3′5-tri-iodo-L-thyronine (T₃) displays high affinity to nuclear thyroid hormone receptors (TRs), which mediate most TH actions. Recent studies have shown hypothyroidism in patients with an increased risk of hepatocellular carcinoma (HCC). MicroRNAs (miRNAs), a class of non-protein-coding RNA, are suggested to control tumor growth by interacting with target genes. However, the clinical significance of T₃/TR-regulated miRNAs in tumors has yet to be established. In the current study, miRNA expression profile screening was performed using SYBR Green-Based qRT-PCR array in TR-overexpressing HepG2 cells. miR-214-3p, which is expressed at low levels in HCC, was stimulated upon T₃ application. The 3′UTR luciferase reporter assay confirmed that the proto-oncogene serine/threonine-protein kinase, PIM-1, is a miR-214-3p target. PIM-1 was decreased upon treatment with miR-214-3p or T₃ stimulation. PIM-1 was highly expressed in HCC, and the effect of PIM-1 on cell proliferation might be mediated by the inhibition of p21. Furthermore, the T₃-induced suppression of cell proliferation was partially rescued upon miR-214-3p knockdown. Our data demonstrate that T₃ induces miR-214-3p expression and suppresses cell proliferation through PIM-1, thus contributing to the inhibition of HCC tumor formation.

Skin Biomarkers for Cystic Fibrosis: A Potential Non-Invasive Approach for Patient Screening

BACKGROUND

Cystic fibrosis (CF) is a disabling genetic disease with an increased prevalence in European heritage populations. Currently, the most used technique for collection of CF samples and diagnosis is provided through uncomfortable tests, with uncertain results, mostly based on chloride concentration in sweat. Since CF mutation induces many metabolic changes in patients, exploring these alterations might be an alternative to visualize potential biomarkers that could be used as interesting tools for further diagnostic upgrade, prioritizing simplicity, low cost, and quickness.

METHODS

This contribution describes an accurate strategy to provide potential biomarkers related to CF, which may be understood as a potential tool for new diagnostic approaches and/or for monitoring disease evolution. Therefore, the present proposal consists of using skin imprints on silica plates as a way of sample collection, followed by direct-infusion high-resolution mass spectrometry and multivariate data analysis, intending to identify metabolic changes in skin composition of CF patients.

RESULTS

Metabolomics analysis allowed identifying chemical markers that can be traced back to CF in patients' skin imprints, differently from control subjects. Seven chemical markers from several molecular classes were elected, represented by bile acids, a glutaric acid derivative, thyrotropin-releasing hormone, an inflammatory mediator, a phosphatidic acid, and diacylglycerol isomers, all reflecting metabolic disturbances that occur due to of CF.

CONCLUSION

The comfortable method of sample collection combined with the identified set of biomarkers represent potential tools that open the range of possibilities to manage CF and follow the disease evolution. This exploratory approach points to new perspectives about the development of diagnostic assay using biomarkers and the management CF.

Thyroid Function in Patients with Cystic Fibrosis: No Longer a Concern?

BACKGROUND

Development of goiter and hypothyroidism has been reported in patients with cystic fibrosis (CF) since the 1970s, especially when treated with iodine-based expectorants. With iodine-containing expectorants no longer in routine use, the prevalence of thyroid dysfunction in CF patients is unknown. This cross-sectional study assessed thyroid function status in a large cohort of CF patients.

METHODS

Sera from ambulatory subjects were obtained from an Institutional Review Board (IRB)-approved biorepository of patients seen at the Emory CF Center between January 1, 2011, and December 31, 2014. Sera from hospitalized subjects were obtained from banked specimens from an IRB-approved inpatient clinical trial. Demographics, forced expiratory volume in one second (FEV1), and medication use were assessed from medical records. Thyroid function tests were measured from the stored sera. Multivariate regression models assessed associations between covariates and thyrotropin (TSH), free thyroxine (fT4), and thyroid dysfunction risk.

RESULTS

A total of 89 subjects (54% male, 91% white, Mage = 24.4 years, median FEV1 63%) were included in the analyses. One subject was on thyroid hormone replacement, 93% were on pancreatic enzyme replacement, and 68% received antibiotics within six months. None had computed tomography scans with intravenous contrast within six months. One patient had positive thyroid peroxidase (TPO) antibodies. Of the 87 subjects with measured TSH values, seven (8%) had abnormal levels (range 0.2-7.6 μIU/mL; one overt, four subclinical hypothyroidism, and two subclinical hyperthyroidism). Of the 56 subjects with measured fT4 values, 19 (34%) had slightly low levels (range 0.49-0.79 ng/dL; 17 isolated mild hypothyroxinemia). A positive correlation between age and body mass index (BMI; p < 0.001) and a negative correlation between age and FEV1 (p = 0.041) were seen. Age, sex, race/ethnicity, BMI, FEV1, hospitalization status, use of pancreatic enzyme or thyroid hormone replacement, recent antibiotic use, and TPO antibody positivity were not predictive of TSH, fT4, or thyroid dysfunction risk. Stratified analyses by hospitalization did not predict TSH or fT4.

CONCLUSIONS

Although 24 (27%) of the patients had abnormal serum thyroid function tests, overt thyroid dysfunction was rare in this cohort of 89 patients with CF. The degree of hypothyroxinemia was marginal, likely due to nonthyroidal illness. There were no significant predictors of thyroid dysfunction.

Apical iodide efflux in thyroid

Thyroid follicular epithelial cells produce thyroxine (T4) and its physiologically active derivative, 3,3',5-triiodothyronine (T3), hormones that regulate critical developmental and metabolic functions. In order for the thyroid to form hormone precursor, iodide, the defining element in thyroid hormone, must cross both blood-facing and luminal sides of the follicular epithelium. The pathway for uptake from blood is well understood, but the mechanism(s) that enable iodide to cross the luminally facing apical membrane remain obscure. This chapter considers the physiological properties of several molecularly characterized anion transport proteins, all of which potentially contribute to the overall mechanism of apical iodide efflux.

Diagnosis and treatment of endocrine comorbidities in patients with cystic fibrosis

PURPOSE OF REVIEW

The aim of this review is to provide an update on various relevant endocrine aspects of care in adolescents and adults with cystic fibrosis.

RECENT FINDINGS

As life expectancy in cystic fibrosis has continuously improved, endocrine complications have become more apparent. The common endocrine complications include cystic fibrosis related diabetes, cystic fibrosis related bone disease, vitamin D deficiency and poor growth and pubertal development. Thyroid and adrenal disorders have also been reported, although the prevalence appears to be less common.

SUMMARY

Endocrine diseases are an increasingly recognized complication that has a significant impact on the overall health of individuals with cystic fibrosis. This review summarizes the updated screening and management of endocrine diseases in the cystic fibrosis population.

Pulmonary hypertension survival effects and treatment options in cystic fibrosis

PURPOSE OF REVIEW

This review discusses the current impact of pulmonary hypertension on the outcome and treatment of cystic fibrosis (CF).

RECENT FINDINGS

Pulmonary hypertension is commonly encountered in advanced lung diseases such as CF. The prevalence of pulmonary hypertension in CF patients varies based on disease severity and methodology used for diagnosis. Chronic alveolar hypoxia is the most likely cause. The majority of recent studies have shown worse survival in CF patients who develop pulmonary hypertension. The impact of pulmonary hypertension-specific therapies on symptomatology and outcomes in CF patients has not been well studied.

SUMMARY

Pulmonary hypertension is common in patients with CF and it occurs largely because of hypoxemia. The presence of pulmonary hypertension in patients with CF is likely associated with worse outcome; however, it remains unknown whether treatment with pulmonary hypertension-specific therapies would be beneficial.

Molecular functions of thyroid hormones and their clinical significance in liver-related diseases

Thyroid hormones (THs) are potent mediators of several physiological processes, including embryonic development, cellular differentiation, metabolism, and cell growth. Triiodothyronine (T3) is the most biologically active TH form. Thyroid hormone receptors (TRs) belong to the nuclear receptor superfamily and mediate the biological functions of T3 via transcriptional regulation. TRs generally form heterodimers with the retinoid X receptor (RXR) and regulate target genes upon T3 stimulation. Research over the past few decades has revealed that disruption of cellular TH signaling triggers chronic liver diseases, including alcoholic or nonalcoholic fatty liver disease and hepatocellular carcinoma (HCC). Animal model experiments and epidemiologic studies to date imply close associations between high TH levels and prevention of liver disease. Moreover, several investigations spanning four decades have reported the therapeutic potential of T3 analogs in lowering lipids, preventing chronic liver disease, and as anticancer agents. Thus, elucidating downstream genes/signaling pathways and molecular mechanisms of TH actions is critical for the treatment of significant public health issues. Here, we have reviewed recent studies focusing on the roles of THs and TRs in several disorders, in particular, liver diseases. We also discuss the potential therapeutic applications of THs and underlying molecular mechanisms.