Relationship between serum iron and blood eosinophil counts in asthmatic adults: data from NHANES 2011-2018

Abstract

BackgroundSo far, quite a few studies have revealed that systemic iron levels are related to asthmatic inflammatory reactions. And most studies have focused on the correlation between systemic iron levels and asthma, with inconsistent findings. Yet, few studies have investigated the connection between serum iron and blood eosinophil counts. Hence, we have explored the connection between serum iron and blood eosinophil counts in asthmatics by utilizing data from NHANES.MethodsA total of 2549 individuals were included in our study after screening NHANES participants from 2011 to 2018. The linear regression model and XGBoost model were used to discuss the potential connection. Linear or nonlinear association was further confirmed by the generalized additive model and the piecewise linear regression model. And we also performed stratified analyses to figure out specific populations.ResultsIn the multivariable linear regression models, we discovered that serum iron levels were inversely related to blood eosinophil counts in asthmatic adults. Simultaneously, we found that for every unit increase in serum iron (umol/L), blood eosinophil counts reduced by 1.41/uL in model 3, which adjusted for all variables excluding the analyzed variables. Furthermore, the XGBoost model of machine learning was applied to assess the relative importance of chosen variables, and it was determined that vitamin C intake, age, vitamin B12 intake, iron intake, and serum iron were the five most important variables on blood eosinophil counts. And the generalized additive model and piecewise linear regression model further verify this linear and inverse association.ConclusionOur investigation discovered that the linear and inverse association of serum iron with blood eosinophil counts in asthmatic adults, indicating that serum iron might be related to changes in the immunological state of asthmatics. Our work offers some new thoughts for next research on asthma management and therapy. Ultimately, we hope that more individuals become aware of the role of iron in the onset, development, and treatment of asthma.

Epidemiological characteristics of asthma-COPD overlap, its association with all-cause mortality, and the mediating role of depressive symptoms: evidence from NHANES 2005–2018

“…By using the commonly used criteria of or available approaches to identifying the focused diseases and clinical conditions, and relying on the data availability within the NHANES 2005–2018, this study grouped participants as follows: 1) the asthma-only group ( N = 2352) [ 1 , 4 , 31 – 33 ], including participants who reported at least one of the following conditions: a) having an episode of asthma or an asthma attack during the past 12 months, b) ever being told by a doctor or other health professionals that they had asthma, and c) using drugs including selective phosphodiesterase-4 inhibitors, mast cell stabilisers, leukotriene modifiers or inhaled corticosteroids, and excluding participants with chronic bronchitis and emphysema; 2) the COPD-only group ( N = 853) [ 4 , 31 , 34 , 35 ], including participants who had at least one of the following conditions: a) reporting having emphysema, b) reporting ever being told they had emphysema, c) having a ratio of forced expiratory volume in 1 s (FEV1) and forceful lung volume (FVC) (FEV1/FVC) after bronchodilator use less than 0.70 in laboratory test, and d) reporting ever being told they had chronic bronchitis and used drugs including selective phosphodiesterase-4 inhibitors, mast cell stabilisers, leukotriene modifiers, inhaled corticosteroids, and excluding participants with asthma; 3) the ACO group ( N = 705) [ 4 , 6 , 36 , 37 ], including participants who met the identification criteria for both asthma and COPD (at least 1 characteristic from each); 4) the non-asthma/COPD group, including participants who did not meet any identification criteria for the asthma-only or COPD-only group. We formed the non-ACO group by combining participants from the asthma-only, COPD-only, and non-asthma/COPD groups.…”

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

“…There are many documents showing that the probability of anemia in patients with asthma is significantly increased (11)(12)(13). Iron is one of the important trace elements that is essential for many biological processes, including the regulation of enzyme activity, oxygen transport, and immune function (14,15), anemia affects a decrease in the strength of the respiratory muscles, including the diaphragm, and reduces lung function (16), which may be a mechanism affecting asthma. Dietary iron supplementation has been reported to reduce airway eosinophilia in animal models to reduce the severity of allergic asthma (17).…”