Anemia as a risk factor for childhood asthma

Linking anemia to asthma: maternal, childhood and adult perspectives from a meta-analysis of 20 studies

BACKGROUND

Anemia has been implicated as a potential risk factor for asthma across different life stages, yet evidence remains inconsistent.

OBJECTIVE

This meta-analysis (CRD420251008733) aimed to evaluate the associations between maternal anemia and offspring asthma, childhood anemia and asthma, and adult anemia and asthma.

METHODS

We searched PubMed, Embase, Web of Science, and Cochrane Library, identifying 20 observational studies. Study quality was assessed using the Newcastle-Ottawa Scale (NOS) and Agency for Healthcare Research and Quality (AHRQ) checklist. Heterogeneity, sensitivity, and publication bias were explored through subgroup analyses, sensitivity tests, and Egger's test. Meta-analysis performed using Stata 17.

RESULTS

Twenty studies involving over 4499364 participants were included. The results showed pooled OR for the association between anemia and asthma (OR = 1.55, 95% CI: 1.36-1.77). Maternal anemia during pregnancy was associated with a modest increase in offspring asthma risk (OR = 1.19, 95% CI: 1.02-1.38), adult anemia was also linked to asthma (OR = 1.94, 95% CI: 1.14-3.30). Childhood anemia showed a stronger association with asthma (OR = 2.22, 95% CI: 1.65-2.99), though Egger's test (p = 0.041) suggested publication bias, with an adjusted OR of 2.03 (95% CI: 1.51-2.74).

CONCLUSIONS

Anemia is significantly associated with an increased risk of asthma, particularly in children. These findings suggest a potential role for anemia screening in asthma management.

Iron Deficiency Impairs Dendritic Cell Development and Function, Compromising Host Anti-Infection Capacity

The prevalence of acute lower respiratory infections in individuals with iron deficiency (ID) has significantly increased, and is correlated with reduced numbers of immune cells and impaired immune function. Dendritic cells (DCs) play a crucial role in combating the influenza A virus (IAV) by initiating adaptive immune responses. However, the impact of ID on DCs and their response to IAV infection remain unclear. This study showed that ID impairs the antigen-presenting ability of DCs, thereby hindering their capacity to mediate T-cell proliferation and clear viruses. The restrictive effects of ID on DCs begin in the bone marrow and specifically affect the monocyte DC progenitor (MDP) stage. A reduction in the number of MDPs and compromised immune potential lead to a decrease in the population and functionality of DCs in the subsequent common DC precursor (CDP) stage in the blood, spleen, and lungs. This study highlights the previously unrecognized impact of ID on DCs and provides valuable insights into immune cell responses and the application of iron supplementation in the fight against viral infections.

The Effect of Iron Deficiency Anemia on Emergency Department Admission in Asthmatic Children

BACKGROUND

Iron deficiency (ID) is the most common nutritional deficiency and cause of anemia in childhood. Iron deficiency anemia (IDA) is a common public health problem in Turkey as in the rest of the World. Asthma is a chronic inflammatory disease of the respiratory tract, affecting approximately 10% of the population in developing countries. There are very few reports available in the medical literature regarding the association of childhood asthma and anemia, as well as the effects of anemia on asthma. This study was designed to investigate the possible relationship between serum iron levels of asthmatic patients and their frequency of emergency admission for asthma exacerbation treatment.

METHODS

The patients who were followed up with a diagnosis of asthma for at least 12 months at the Ankara Child Health and Diseases Hematology Oncology Training and Research Hospital, whose current age is below 21, and whose serum iron, total iron binding capacity, and ferritin levels were checked between 2017 and 2019, were included in the study.

RESULTS

In the assessment of 612 patients diagnosed with asthma, 105 individuals, constituting 18.4% of those under asthma follow-up, were identified as having anemia. Additionally, ID not progressing to anemia was observed in 120 patients, accounting for 21.1% of the total. Individuals with IDA and/or ID alone experienced a significantly higher frequency of emergency admissions for asthma exacerbations. Moreover, ID and/or IDA were established as independent risk factors linked to emergency admissions for asthma exacerbations. odds ratio = 1.56, confidence interval = 1.06-2.30 p = 0.022.

CONCLUSION

In conclusion, it may be recommended to follow up the hemoglobin and iron parameters of asthmatic patients and to take nutritional and/or supportive preparations to keep them at a high level.

Determinants of Anemia in Schoolchildren in the Highland Bolivia

Anemia is a health problem of concern among schoolchildren in underprivileged rural regions, where recurrent parasitic infections are common. A cross-sectional study was conducted in 229 schoolchildren in rural highland Bolivia in the department of La Paz, an area with a high prevalence of protozoan and helminth infections, to determine the types and mechanisms of anemia. A substantial proportion of children (40.2%) were found to be anemic based on hemoglobin measurements. No associations were found between low hemoglobin levels and helminth or protozoan infections when evaluating infectious causes of anemia, nor with Giardia lamblia or Blastocystis hominis, which are associated with iron deficiency and nutrient malabsorption and were highly prevalent in this study. The significant association between anemia and hypochromia suggests iron deficiency, aligned with low hemoglobin levels. A total of 39 out of 150 children (26%) had markers consistent with iron deficiency anemia (IDA), 26 out of 127 children (20%) met the criteria for anemia of inflammation (AI). Furthermore, 12 of the 127 tested children (9.4%) met the criteria for mixed AI with IDA according to the soluble transferrin receptor (sTfR)/log ferritin levels, which increased significantly due to overall infections by Hymenolepis nana and Ascaris lumbricoides helminths. The findings highlight the need for integrated public health interventions to address iron nutrition and parasitic infections to effectively prevent anemia in this vulnerable population.

Exploring the Interplay between Asthma and Hemoglobinopathies: A Comprehensive Review

Asthma, a prevalent chronic respiratory condition characterized by inflammation of the airways and bronchoconstriction, has demonstrated a potential association with hemoglobinopathies such as thalassemia and sickle cell disease (SCD). Numerous studies have highlighted a higher prevalence of asthma among thalassemia patients compared to the general population, with rates ranging around 30%. Similarly, asthma frequently coexists with SCD, affecting approximately 20-48% of patients. Children with SCD often experience heightened lower airway obstruction and airway hyper-reactivity. Notably, the presence of asthma in SCD exacerbates respiratory symptoms and increases the risk of severe complications like acute chest syndrome, stroke, vaso-occlusive episodes, and early mortality. Several studies have noted a decrease in various cytokines such as IFN-γ and IL-10, along with higher levels of both IL-6 and IL-8, suggesting an overactivation of pro-inflammatory mechanisms in patients with hemoglobinopathies, which could trigger inflammatory conditions such as asthma. The exact mechanisms driving this association are better elucidated but may involve factors such as chronic inflammation, oxidative stress, and immune dysregulation associated with thalassemia-related complications like chronic hemolytic anemia and iron overload. This review aims to comprehensively analyze the relationship between asthma and hemoglobinopathies, with a focus on thalassemia and SCD. It emphasizes the importance of interdisciplinary collaboration among pulmonologists, hematologists, and other healthcare professionals to effectively manage this complex interplay. Understanding this link is crucial for improving care and outcomes in affected individuals.

Causal relationship between iron deficiency anemia and asthma: a Mendelian randomization study

Background

Observational studies have suggested an association between iron deficiency anemia (IDA) and asthma, which may affect the occurrence of asthma. However, whether IDA is a new management goal for asthma remains to be determined.

Objective

We conducted a two-sample Mendelian randomization(MR)analysis to assess the association between IDA and asthma.

Methods

We performed a two-sample MR study to assess a causal relationship between IDA (ncase = 12,434, ncontrol = 59,827) and asthma (ncase = 20,629, ncontrol = 135,449). Inverse variance weighted (IVW) was used as the primary method for the analyses. Furthermore, we used weighted medians and MR-Egger to enhance robustness. Data linking genetic variation to IDA and asthma were combined to assess the impact of IDA on asthma risk.

Results

There are five single nucleotide polymorphisms (SNPs) were used as genetic tool variables for exposure factors. Genetically determined IDA was significantly associated with an increased risk of asthma (OR = 1.37, 95% CI: 1.09-1.72, p = 0.007). There was little heterogeneity in the MR studies and no evidence of level pleiotropy was found.

Conclusions

In our MR study, our findings emphasize that IDA may be associated with a high risk of asthma, indicating a potential role for IDA in the development of asthma. Future research needs to elucidate its potential mechanisms to pave the way for the prevention and treatment of asthma.

Iron controls the development of airway hyperreactivity by regulating ILC2 metabolism and effector function

Group 2 innate lymphoid cells (ILC2s) rapidly induce a type 2 inflammation in the lungs in response to allergens. Here, we focused on the role of iron, a critical nutritional trace element, on ILC2 function and asthma pathogenesis. We found that transferrin receptor 1 (TfR1) is rapidly up-regulated and functional during ILC2 activation in the lungs, and blocking transferrin uptake reduces ILC2 expansion and activation. Iron deprivation reprogrammed ILC2 metabolism, inducing a HIF-1α-driven up-regulation of glycolysis and inhibition of oxidative mitochondrial activity. Consequently, we observed that in vivo iron chelation or induction of hypoferremia reduced the development of airway hyperreactivity in experimental models of ILC2-driven allergic asthma. Human circulating ILC2s rapidly induced TfR1 during activation, whereas inhibition of iron uptake or iron deprivation reduced effector functions. Last, we found a negative relationship between circulating ILC2 TfR1 expression and airway function in cohorts of patients with asthma. Collectively, our studies define cellular iron as a critical regulator of ILC2 function.

Frequency of Gastrointestinal Parasites, Anemia, and Nutritional Status among Children from Different Geographical Regions of Bolivia

The study aimed to measure the frequency of occurrence of infections with helminths, protozoa, and risk factors of undernutrition and anemia among schoolchildren from the Bolivian highland (altiplano) and lowland (subtropical) rural regions, with a high frequency of gastrointestinal parasite infections. Cross-sectional data were collected from 790 children, 5-13 years old. Microscopic examination of stool using the Ritchie technique, hemoglobin testing using the HemoCue analyzer, and anthropometric measurements were performed. Over 60% and 20% of children were infected with protozoa and helminth parasites, respectively. Infections caused by pathogenic Hymenolepis nana (15.7-5.2%), Ascaris lumbricoides (41.9-28.5%), Giardia lamblia (30.1-11.2%), Entamoeba histolytica (5.7-0.7%), and nonpathogenic Entamoeba coli (48.9-16%), Blastocystis hominis (40.2-28.5%), Iodamoeba butschli (16.1-2.5%), Chilomastix mesnili (19.2-7.3%), and Entamoeba histolytica/dispar (7.4-5.5%) parasites, were more prevalent in the highlands than the lowlands. Single parasitic infections were more prevalent in the lowlands; polyparasitism of light or heavy intensity predominated in the highlands. A strongly increased risk of anemia and a low prevalence of wasting were determined in children in the highlands. A higher risk for stunting was associated with children of older age, and a low burden of intestinal helminths would prevent wasting in children of highlands. Infections with A. lumbricoides and G. lamblia pathogens in older children were not significant covariates for stunting. Environmental, nutritional, and parasitic factors may predispose to anemia in the highlands. A nutritional intervention and parasite control effort will substantially improve children´s health in the highlands.

Dysregulation of iron homeostasis in airways associated with persistent preschool wheezing

BACKGROUND

Currently, there are no reliable clinical tools available to identify persistent asthma symptoms among preschool children with recurrent wheezing. We investigated iron homeostasis in the airways of preschoolers with recurrent wheezing and assessed whether iron homeostasis-related indices may reliably predict persistent wheezing.

METHODS

Iron levels and mRNA expression levels of iron homeostasis molecules were examined in bronchoalveolar lavage samples from 89 preschoolers with recurrent wheezing and 56 controls, with a 12-month follow-up conducted. Risk factors for persistent wheezing were identified using least absolute shrinkage and selection operator and multivariate logistic regression. The addition of predictive values of iron indices to the modified Asthma Predictive Index (mAPI) or clinical predictors was determined using area under receiver operating characteristic curves (AUC).

RESULTS

Preschoolers with recurrent wheezing had reduced iron levels in their airways, associated with significantly decreased expression of iron export molecule SLC40A1 and increased expression of iron intake factor TFR1 and iron storage factors FTH and FTL. Risk factors for persistent wheezing included mAPI positivity, iron predictors (lower expression of SLC40A1 and higher expression of FTL), and clinical predictors (aeroallergen sensitivity, shorter breastfeeding duration, and earlier age of first wheezing episode). The addition of information on iron predictors significantly enhanced the power of clinical predictors (AUC: 84%, increase of 12%) and mAPI (AUC: 81%, increase of 14%).

CONCLUSIONS

Iron homeostasis is altered in the airways of preschoolers with recurrent wheezing. Adding information on iron-related indices to clinical information significantly improves accurate prediction of persistent wheezing in preschool-aged children.

Low Serum Levels of Zinc, Selenium, and Vitamin D3 Are Biomarkers of Airway Inflammation and Poor Asthma Control: A Two-Centre Study

Background Asthma is a chronic inflammatory disease with its control being affected by underlying oxidative stress. Trace elements, along with vitamin D3, play an important role in immune alterations leading to an imbalance of Th1/Th2 helper cells. However, their role in asthma pathogenesis and control is inconsistent and inconclusive. The objective of our study was to assess levels of serum trace elements like zinc, copper, selenium, iron, magnesium, vitamin D3 levels, IgE, and HsCRP in asthmatic children, compare with healthy controls, and assess their association with the level of asthma control. Methods A cross-sectional study was conducted from 2019 to 2021 enrolling 100 asthmatic children and 75 healthy controls. The level of asthma control was assessed as uncontrolled, partly controlled, and controlled asthma as per GINA Guidelines. Mean and standard deviation were calculated for each element and mean differences between groups were analyzed by student t-test. A p-value of <0.05 was considered significant. Results The mean age was 8.75±2.89 yrs in cases and 9.04±2.79 in controls. A total of 57.6% of cases had atopic comorbidities. The mean serum zinc levels were 51±12.8 mg/dl, which was very low in asthmatic children as compared to 60±18.2mg/dl (p-value 0.0002) in healthy controls. Serum selenium was 13±3 µg/dl in asthmatics vs. 15±4 µg/dl (p-value 0.0002) in healthy controls. Serum copper was 115.2±21.92µg/dl vs. 125.3±31.99µg/dl (p-value 0.015), Serum vitamin D3 levels were 13.07±7.82ng/ml vs. 17.82±14.62 ng/ml(p-value 0.006) in both groups, respectively. SIgE and HsCRP were high in asthmatic children suggestive of eosinophilic inflammation. Serum zinc was 49±5.45 mg/dl in the uncontrolled group, 53±6.1 in the partly controlled, and 58±8.0 in the well-controlled group (p<0.0001). Serum selenium was 10± 3.0 µg/dl in the uncontrolled group vs. 13± 2.0 and 14± 2.0 µg/dl in the partly controlled and well-controlled groups, respectively (p-value <0.0001). Vitamin D3 was significantly low (9.32±5.95ng/dl) in the uncontrolled group vs. 12.99±4.97 and 13.40±5.92 ng/dl(p<0.005) in the partly controlled and well-controlled groups respectively. Vitamin D3 showed a strong positive correlation with zinc (r=0.4,p< 0.0001) and a negative correlation with inflammatory markers like SIgE and HsCRP. Conclusion Children with asthma had low zinc, selenium, and vitamin D3 levels, and were associated with airway inflammation and poor asthma control.

Advances in respiratory physiology in mouse models of experimental asthma

Recent advances in mouse models of experimental asthma coupled with vast improvements in systems that assess respiratory physiology have considerably increased the accuracy and human relevance of the outputs from these studies. In fact, these models have become important pre-clinical testing platforms with proven value and their capacity to be rapidly adapted to interrogate emerging clinical concepts, including the recent discovery of different asthma phenotypes and endotypes, has accelerated the discovery of disease-causing mechanisms and increased our understanding of asthma pathogenesis and the associated effects on lung physiology. In this review, we discuss key distinctions in respiratory physiology between asthma and severe asthma, including the magnitude of airway hyperresponsiveness and recently discovered disease drivers that underpin this phenomenon such as structural changes, airway remodeling, airway smooth muscle hypertrophy, altered airway smooth muscle calcium signaling, and inflammation. We also explore state-of-the-art mouse lung function measurement techniques that accurately recapitulate the human scenario as well as recent advances in precision cut lung slices and cell culture systems. Furthermore, we consider how these techniques have been applied to recently developed mouse models of asthma, severe asthma, and asthma-chronic obstructive pulmonary disease overlap, to examine the effects of clinically relevant exposures (including ovalbumin, house dust mite antigen in the absence or presence of cigarette smoke, cockroach allergen, pollen, and respiratory microbes) and to increase our understanding of lung physiology in these diseases and identify new therapeutic targets. Lastly, we focus on recent studies that examine the effects of diet on asthma outcomes, including high fat diet and asthma, low iron diet during pregnancy and predisposition to asthma development in offspring, and environmental exposures on asthma outcomes. We conclude our review with a discussion of new clinical concepts in asthma and severe asthma that warrant investigation and how we could utilize mouse models and advanced lung physiology measurement systems to identify factors and mechanisms with potential for therapeutic targeting.

Transcriptomic analysis identified SLC40A1 as a key iron metabolism-related gene in airway macrophages in childhood allergic asthma

Introduction: Asthma is the most common chronic condition in children, with allergic asthma being the most common phenotype, accounting for approximately 80% of cases. Growing evidence suggests that disruption of iron homeostasis and iron regulatory molecules may be associated with childhood allergic asthma. However, the underlying molecular mechanism remains unclear. Methods: Three childhood asthma gene expression datasets were analyzed to detect aberrant expression profiles of iron metabolism-related genes in the airways of children with allergic asthma. Common iron metabolism-related differentially expressed genes (DEGs) across the three datasets were identified and were subjected to functional enrichment analysis. Possible correlations between key iron metabolism-related DEGs and type 2 airway inflammatory genes were investigated. Single-cell transcriptome analysis further identified major airway cell subpopulations driving key gene expression. Key iron metabolism-related gene SLC40A1 was validated in bronchoalveolar lavage (BAL) cells from childhood asthmatics with control individuals by quantitative reverse transcription-polymerase chain reaction (qRT-PCR) and immunofluorescence. The intracellular iron content in BAL cells was assessed by Perls iron staining and the iron levels in BAL supernatant was measured by iron assay to assess airway iron metabolism status in childhood asthmatics. Results: Five common iron metabolism-related DEGs were identified, which were functionally related to iron homeostasis. Among these genes, downregulated SLC40A1 was strongly correlated with type 2 airway inflammatory markers and the gene signature of SLC40A1 could potentially be used to determine type 2-high and type 2-low subsets in childhood allergic asthmatics. Further single-cell transcriptomic analysis identified airway macrophages driving SLC40A1 expression. Immunofluorescence staining revealed colocalization of FPN (encoded by SLC40A1) and macrophage marker CD68. Down-regulation of SLC40A1 (FPN) was validated by qRT-PCR and immunofluorescence analysis. Results further indicated reduced iron levels in the BAL fluid, but increased iron accumulation in BAL cells in childhood allergic asthma patients. Furthermore, decreased expression of SLC40A1 was closely correlated with reduced iron levels in the airways of children with allergic asthma. Discussion: Overall, these findings reveal the potential role of the iron metabolism-related gene SLC40A1 in the pathogenesis of childhood allergic asthma.

Perimenstrual Asthma in Adolescents: A Shared Condition in Pediatric and Gynecological Endocrinology

Asthma is a frequent medical condition in adolescence. The worsening of the most common symptoms perimenstrually is defined as perimenstrual asthma (PMA). The cause of PMA remains unclear, but a role for hormonal milieu is plausible. Data on PMA in adolescents are limited, and its management is not fully established. We aimed to discuss the PMA phenomenon in young females from pathophysiology to preventive strategies, focusing on the relationship with the hormonal pattern. The fluctuation of estrogens at ovulation and before menstruation and the progesterone secretion during the luteal phase and its subsequent withdrawal seem to be the culprits, because the deterioration of asthma is cyclical during the luteal phase and/or during the first days of the menstrual cycle. Conventional asthma therapies are not always effective for PMA. Preventive strategies may include innovative hormonal contraception. Even a possible beneficial effect of other hormonal treatments, including estrogens, progestogens, and androgens, as well as leukotriene receptor antagonists and explorative approach using microbial-directed therapy, is considered. The underlying mechanisms, through which sex-hormone fluctuations influence asthma symptoms, represent a challenge in the clinical management of such a distressing condition. Further studies focused on young females are mandatory to promote adolescent health.

Causal effect of iron status on lung function: A Mendelian randomization study

Background

The association between systemic iron status and lung function was conflicting in observational studies. We aim to explore the potential causal relationships between iron status and the levels of lung function using the two-sample Mendelian randomization (MR) design.

Methods

Genetic instruments associated with iron status biomarkers were retrieved from the Genetics of Iron Status (GIS) consortium (N = 48,972). Summary statistics of these genetic instruments with lung function were extracted from a meta-analysis of UK Biobank and SpiroMeta consortium (N = 400,102). The main analyses were performed using the inverse-variance weighted method, and complemented by multiple sensitivity analyses.

Results

Based on conservative genetic instruments, MR analyses showed that genetically predicted higher iron (beta: 0.036 per 1 SD increase, 95% confidence interval (CI): 0.016 to 0.056, P = 3.51 × 10^-4), log10-transformed ferritin (beta: 0.081, 95% CI: 0.047 to 0.116, P = 4.11 × 10^-6), and transferrin saturation (beta: 0.027, 95% CI: 0.015 to 0.038, P = 1.09 × 10^-5) were associated with increased forced expiratory volume in 1 s (FEV1), whereas higher transferrin was associated with decreased FEV1 (beta: -0.036, 95% CI: -0.064 to -0.008, P = 0.01). A significant positive association between iron status and forced vital capacity (FVC) was also observed. However, there is no causal association between iron status and FEV1-to-FVC ratio (P = 0.10). Similar results were obtained from the liberal instruments analyses and multiple sensitivity analyses.

Conclusion

Our study provided strong evidence to support that higher iron status is causally associated with higher levels of FEV1 and FVC, but has no impact on airway obstruction, confirming iron status as an important target for lung function management.

Mineral Micronutrients in Asthma

Asthma represents one of the most common medical issues in the modern world. It is a chronic inflammatory disease characterized by persistent inflammation of the airways and disturbances in redox status, leading to hyperresponsiveness of bronchi and airway obstruction. Apart from classical risk factors such as air pollution, family history, allergies, or obesity, disturbances of the levels of micronutrients lead to impairments in the defense mechanisms of the affected organism against oxidative stress and proinflammatory stimuli. In the present review, the impact of micronutrients on the prevalence, severity, and possible risk factors of asthma is discussed. Although the influence of classical micronutrients such as selenium, copper, or zinc are well known, the effects of those such as iodine or manganese are only rarely mentioned. As a consequence, the aim of this paper is to demonstrate how disturbances in the levels of micronutrients and their supplementation might affect the course of asthma.

Pediatric thalassemic patients have higher incidence of asthma: A nationwide population-based retrospective cohort study

Introduction

Patients with hemoglobinopathies have been reported to have higher rates of pulmonary complications. Few studies have investigated the association between thalassemia and asthma in children.

Methods

We used the data of one million individuals randomly selected from the Registry for Beneficiaries of the National Health Insurance Research Database. One thalassemic child was matched with four control children without thalassemia according to sex, birth year, birth season, prematurity, and previous enteroviral infection.

Results

A total of 800 hundred thalassemic children and 3200 controls were included. Children with thalassemia had higher rates of developing asthma (41.81 vs 25.70 per 1000 person-years, P < 0.001) than the non-thalassemia controls with an adjusted hazard ratio of 1.37 (95% confidence interval [CI] = 1.19–1.58). Boys in the thalassemia cohort had a significantly higher adjusted incidence hazard ratio (IRR) of asthma than those in the non-thalassemia cohort (adjusted IRR = 1.45, 95% CI = 1.02–1.73). The risk of atopic and nonatopic asthma was higher in the thalassemia cohort than in the non-thalassemia cohort (IRR = 1.3, 1.61, respectively).

Conclusions

Children with thalassemia were more likely to develop asthma. More attention should be paid to the early diagnosis of asthma and prevention of asthma attacks.

Crucial role for lung iron level and regulation in the pathogenesis and severity of asthma

Accumulating evidence highlights links between iron regulation and respiratory disease. Here, we assessed the relationship between iron levels and regulatory responses in clinical and experimental asthma.We show that cell-free iron levels are reduced in the bronchoalveolar lavage (BAL) supernatant of severe or mild-moderate asthma patients and correlate with lower forced expiratory volume in 1 s (FEV₁). Conversely, iron-loaded cell numbers were increased in BAL in these patients and with lower FEV₁/forced vital capacity (FVC) ratio. The airway tissue expression of the iron sequestration molecules divalent metal transporter 1 (DMT1) and transferrin receptor 1 (TFR1) are increased in asthma, with TFR1 expression correlating with reduced lung function and increased Type-2 (T2) inflammatory responses in the airways. Furthermore, pulmonary iron levels are increased in a house dust mite (HDM)-induced model of experimental asthma in association with augmented Tfr1 expression in airway tissue, similar to human disease. We show that macrophages are the predominant source of increased Tfr1 and Tfr1⁺ macrophages have increased Il13 expression. We also show that increased iron levels induce increased pro-inflammatory cytokine and/or extracellular matrix (ECM) responses in human airway smooth muscle (ASM) cells and fibroblasts ex vivo and induce key features of asthma in vivo, including airway hyper-responsiveness (AHR) and fibrosis, and T2 inflammatory responses.Together these complementary clinical and experimental data highlight the importance of altered pulmonary iron levels and regulation in asthma, and the need for a greater focus on the role and potential therapeutic targeting of iron in the pathogenesis and severity of disease.

The Transferrin Receptor CD71 Delineates Functionally Distinct Airway Macrophage Subsets during Idiopathic Pulmonary Fibrosis

Rationale: Idiopathic pulmonary fibrosis (IPF) is a devastating progressive disease with limited therapeutic options. Airway macrophages (AMs) are key components of the defense of the airways and are implicated in the pathogenesis of IPF. Alterations in iron metabolism have been described during fibrotic lung disease and in murine models of lung fibrosis. However, the role of transferrin receptor 1 (CD71)-expressing AMs in IPF is not known. Objectives: To assess the role of CD71-expressing AMs in the IPF lung. Methods: We used multiparametric flow cytometry, gene expression analysis, and phagocytosis/transferrin uptake assays to delineate the role of AMs expressing or lacking CD71 in the BAL of patients with IPF and of healthy control subjects. Measurements and Main Results: There was a distinct increase in proportions of AMs lacking CD71 in patients with IPF compared with healthy control subjects. Concentrations of BAL transferrin were enhanced in IPF-BAL, and furthermore, CD71- AMs had an impaired ability to sequester transferrin. CD71+ and CD71- AMs were phenotypically, functionally, and transcriptionally distinct, with CD71- AMs characterized by reduced expression of markers of macrophage maturity, impaired phagocytosis, and enhanced expression of profibrotic genes. Importantly, proportions of AMs lacking CD71 were independently associated with worse survival, underlining the importance of this population in IPF and as a potential therapeutic target. Conclusions: Taken together, these data highlight how CD71 delineates AM subsets that play distinct roles in IPF and furthermore show that CD71- AMs may be an important pathogenic component of fibrotic lung disease.

Benzo[a]pyrene is associated with dysregulated myelo-lymphoid hematopoiesis in asthmatic children

BACKGROUND

The extent to which ambient benzo[a]pyrene (B[a]P) contributes to mechanistically distinct de novo asthma remains unknown.

OBJECTIVES

To identify molecular signatures and regulatory networks underlying childhood exposure to ambient B[a]P and asthma, using robust and unbiased systems biology approaches.

METHODS

Clinically confirmed asthmatic (n = 191) vs. control (n = 194) children (aged, 7-15) were enrolled from a polluted urban center and semi-rural region in Czech Republic. Contemporaneous B[a]P concentration, gene expressions, DNA methylation data were analyzed against asthma diagnosis, as well as a modified prognostic index of asthma, using integrative multiscale co-expression network analysis. Sample-wise cell type compositions were inferred by a machine learning approach (i.e. CIBERSORT) with reference gene expressions of purified 38 distinct hematopoietic cell states from umbilical cord (i.e. stem cell/progenitors) or peripheral blood (i.e. lymphocytes).

RESULTS

The median outdoor B[a]P was increased near the homes of the urban children with 'moderate' or 'severe' prognostic markers of asthma, but not in the urban controls. An elevated B[a]P induced epigenetic suppression of NF-κB inflammation, decreased Natural Killer T (NKT) cells and activated anti-inflammatory IL10-secreting CD8+ T effective memory cells. B[a]P was positively correlated with an increased expression of a heme biosynthesis gene, ALAS2, which in turn, appears to promote concurrent increase of neutrophilic metamyelocyte and mature CD71^low erythroid cells. Furthermore, erythroid-specific master transcription regulator gene (GATA1), glutathione transferase genes (GSTM1 and GSTM3) and Eosinophil marker (IL5RA) were simultaneously activated in the urban asthma cases.

CONCLUSIONS

B[a]P might contribute to concurrent suppression of pro-inflammatory (e.g. NF-κB mediated NKT cells), and activation of anti-inflammatory pathways (e.g. IL10-secreting CD8+ T cells) in the urban asthmatic children. In addition, B[a]P appears to elevate heme biosynthesis, which in turn, promotes neutrophilic metamyelocyte expansion and reduction of CD71⁺ erythroids.

Implications of the Iron Deficiency in Lower Tract Respiratory Acute Infections in Toddlers

Iron deficiency anemia can result in an abnormal immune response and an increased incidence of the respiratory tract infections. In this study we analyzed statistically the association of acute lower respiratory tract infections with anemic status and associated risk factors for a number of 166 toddlers (1-3 years), using a control group of 26 cases without infectious status. The statistical analysis indicated the significant association of the infectious status with the anemic status of the patients as well as with the rural living areas, non-natural nutrition, prematurity and respiratory history. At the same time, we found a statistically significant association of anemic status with rural living areas and non-natural diet. The results obtained can be used to stratify patients for standardized treatment to regulate the iron metabolism and implicitly to combat the infectious disease.

Role of iron in the pathogenesis of respiratory disease

Iron is essential for many biological processes, however, too much or too little iron can result in a wide variety of pathological consequences, depending on the organ system, tissue or cell type affected. In order to reduce pathogenesis, iron levels are tightly controlled in throughout the body by regulatory systems that control iron absorption, systemic transport and cellular uptake and storage. Altered iron levels and/or dysregulated homeostasis have been associated with several lung diseases, including chronic obstructive pulmonary disease, lung cancer, cystic fibrosis, idiopathic pulmonary fibrosis and asthma. However, the mechanisms that underpin these associations and whether iron plays a key role in the pathogenesis of lung disease are yet to be fully elucidated. Furthermore, in order to survive and replicate, pathogenic micro-organisms have evolved strategies to source host iron, including freeing iron from cells and proteins that store and transport iron. To counter these microbial strategies, mammals have evolved immune-mediated defence mechanisms that reduce iron availability to pathogens. This interplay between iron, infection and immunity has important ramifications for the pathogenesis and management of human respiratory infections and diseases. An increased understanding of the role that iron plays in the pathogenesis of lung disease and respiratory infections may help inform novel therapeutic strategies. Here we review the clinical and experimental evidence that highlights the potential importance of iron in respiratory diseases and infections.

Asthma as a disruption in iron homeostasis

Over several decades, asthma has evolved from being recognized as a single disease to include a diverse group of phenotypes with dissimilar natural histories, pathophysiologies, responses to treatment, and distinctive molecular pathways. With the application of Occam's razor to asthma, it is proposed that there is one cause underlying the numerous phenotypes of this disease and that the responsible molecular pathway is a deficiency of iron in the lung tissues. This deficiency can be either absolute (e.g. asthma in the neonate and during both pregnancy and menstruation) or functional (e.g. asthma associated with infections, smoking, and obesity). Comparable associations between asthma co-morbidity (e.g. eczema, urticaria, restless leg syndrome, and pulmonary hypertension) with iron deficiency support such a shared mechanistic pathway. Therapies directed at asthma demonstrate a capacity to impact iron homeostasis, further strengthening the relationship. Finally, pathophysiologic events producing asthma, including inflammation, increases in Th2 cells, and muscle contraction, can correlate with iron availability. Recognition of a potential association between asthma and an absolute and/or functional iron deficiency suggests specific therapeutic interventions including inhaled iron.

Perimenstrual asthma: from pathophysiology to treatment strategies

The prevalence of asthma is about 9,7 % in women and 5,5 % in men. Asthma can deteriorate during the perimenstrual period, a phenomenon known as perimenstrual asthma (PMA), which represents a unique, highly symptomatic asthma phenotype. It is distinguished from traditional allergic asthma by aspirin sensitivity, less atopy, and lower lung capacity. PMA incidence is reported to vary between 19 and 40 % of asthmatic women. The presence of PMA has been related to increases in asthma-related emergency department visits, hospitalizations and emergency treatment including intubations. It is hypothesized that hormonal status may influence asthma in women, focusing on the role of sex hormones, and specifically on the impact of estrogens' fluctuations at ovulation and before periods. This paper will focus on the pathophysiology of hormone triggered cycle related inflammatory/allergic events and their relation with asthma. We reviewed the scientific literature on Pubmed database for studies on PMA. Key word were PMA, mastcells, estrogens, inflammation, oral contraception, hormonal replacement therapy (HRT), and hormone free interval (HFI). Special attention will be devoted to the possibility of reducing the perimenstrual worsening of asthma and associated symptoms by reducing estrogens fluctuations, with appropriate hormonal contraception and reduced HFI. This novel therapeutical approach will be finally discussed.

Association between anemia and bronchopulmonary dysplasia in preterm infants

Anemia is commonly seen in preterm infants. It may reduce the capacity of hemoglobin to transport oxygen throughout the body and may result in tissue and organ dysfunction. This study aimed to investigate the effect of anemia on the development of bronchopulmonary dysplasia (BPD) in preterm infants. 243 infants who were admitted to BaYi Children’s Hospital Affiliated to Clinical Medical College in Beijing Military General Hospital with gestational age (GA) less than 32 weeks from February, 2014 to February, 2015 were included in the study. Maternal and infant data were recorded. Multivarariate logistic regression analysis was performed to determine the association between anemia and BPD. Of 243 preterm infants, the incidence of anemia was higher in BPD patients than non-BPD patients (p < 0.001). Mean Hct in BPD patients was lower than non-BPD patients at different time points in 1d, 7d, 14d, and 21d. Controlling for other confounding factors, early anemia was associated with an increased risk of BPD. Number of transfusions is also a significant risk factor for BPD (p = 0.001). Therefore, prevention and treatment of early anemia is necessary and reducing number of transfusions may reduce the incidence of BPD in preterm infants.

Iron status is associated with asthma and lung function in US women

BACKGROUND

Asthma and iron deficiency are common conditions. Whether iron status affects the risk of asthma is unclear.

OBJECTIVE

To determine the relationship between iron status and asthma, lung function, and pulmonary inflammation.

METHODS

Relationships between measures of iron status (serum ferritin, serum soluble transferrin receptor (sTfR), and sTfR/log10ferritin (sTfR-F Index)) and asthma, lung function, and pulmonary inflammation were examined in women 20-49 years in the National Health and Nutrition Examination Survey. Logistic, linear, and quadratic regression models accounting for the survey design of NHANES were used to evaluate associations between iron status and asthma-related outcomes and were adjusted for race/ethnicity, age, smoking status, income, and BMI.

RESULTS

Approximately 16% reported a lifetime history of asthma, 9% reported current asthma, and 5% reported a recent asthma episode/attack (n = 2906). Increased ferritin (iron stores) was associated with decreased odds of lifetime asthma, current asthma, and asthma attacks/episodes in the range of ferritin linearly correlated with iron stores (20-300ng/ml). The highest quintile of ferritin (>76 ng/ml) was also associated with a decreased odds of asthma. Ferritin levels were not associated with FEV1. Increased values of the sTfR-F Index and sTfR, indicating lower body iron and higher tissue iron need, respectively, were associated with decreased FEV1, but neither was associated with asthma. None of the iron indices were associated with FeNO.

CONCLUSION

In US women, higher iron stores were inversely associated with asthma and lower body iron and higher tissue iron need were associated with lower lung function. Together, these findings suggest that iron status may play a role in asthma and lung function in US women.

Association between anemia and packed cell transfusion and outcomes of ventricular septal defect and atrioventricular canal repair in children

Data on the prevalence and impact of anemia and packed red blood cell (PRBC) transfusions in children with congenital heart disease are limited. Our objectives were to determine the prevalence of anemia and its impact and the impact of PRBC transfusion in the initial 5 days after surgical repair on postoperative outcomes in infants with ventricular septal defect (VSD) and atrioventricular (AV) canal. Retrospective chart review of infants (1 year old) (n = 195) with AV canal or VSD who underwent surgical repair at Children's Hospital of Michigan during a 10-year period. Statistical analyses (SPSS 17.0) included Chi square and Student t test as well as regression analysis with significance set at p = 0.05. Preoperative anemia was diagnosed in 45 of 195 (23%) children. Anemic infants had VSD more frequently (80%), significantly shorter bypass and cross-clamp durations, and higher red cell distribution widths. Postoperative outcomes and PRBC transfusions were similar in the groups. On regression analysis, AV canal was associated with a significantly lower (odds ratio 0.21; 95% confidence interval 0.07-0.68, p = 0.009) risk of anemia. Infants who received a PRBC transfusion (n = 42) had significantly lower birth weights as well as weights at surgery and longer postoperative durations of pressor use, ventilation, oxygen supplementation, and length of stay than those who did not (n = 153) receive transfusions. PRBC transfusion was independently associated with longer postoperative length of stay, oxygen, pressor use, and ventilator duration. Approximately 23% of infants with AV canal or VSD are anemic. PRBC transfusions in the initial 5 postoperative days, but not anemia, are independently associated with adverse postoperative outcomes. Further studies to evaluate conservative transfusion strategies in this population are needed.