Iron overload causes a mild and transient increase in acute lung injury

Maternal hemoglobin and iron status in early pregnancy and risk of respiratory tract infections in childhood: A population-based prospective cohort study

BACKGROUND

Maternal hemoglobin and iron status measures during pregnancy might affect the developing fetal respiratory system leading to adverse respiratory conditions. Our aim was to assess the associations of maternal hemoglobin and iron status measures during pregnancy with the risk of respiratory tract infections in children until 10 years of age.

METHODS

In a population-based cohort study among 5134 mother-child pairs, maternal hemoglobin and iron status including ferritin, transferrin, and transferrin saturation were measured during early pregnancy. In children, physician-attended respiratory tract infections from age 6 months until 10 years were assessed by questionnaires. Confounder-adjusted generalized estimating equation modeling was applied.

RESULTS

After taking multiple testing into account, high maternal ferritin concentrations and low maternal transferrin saturation during pregnancy were associated with an overall increased risk of upper, not lower, respiratory tract infections until age 10 years of the child [OR (95% CI: 1.23 (1.10, 1.38) and 1.28 (1.12, 1.47), respectively)]. High maternal transferrin saturation during pregnancy was associated with a decreased and increased risk of upper respiratory tract infections at 1 and 6 years, respectively, [OR (95% CI: 0.60 (0.44, 0.83) and 1.54 (1.17, 2.02))]. Observed associations were suggested to be U-shaped (p-values for non-linearity ≤.001). Maternal hemoglobin and iron status measures during pregnancy were not consistently associated with child's gastroenteritis and urinary tract infections, as proxies for general infection effects.

CONCLUSION

High maternal ferritin and low transferrin saturation concentrations during early pregnancy were most consistently associated with an overall increased risk of child's upper, not lower, respiratory tract infections.

Iron Chelation as a Potential Therapeutic Approach in Acute Lung Injury

Acute lung injury (ALI) has been challenging health care systems since before the COVID-19 pandemic due to its morbidity, mortality, and length of hospital stay. In view of the complex pathogenesis of ALI, effective strategies for its prevention and treatment are still lacking. A growing body of evidence suggests that iron dysregulation is a common characteristic in many subtypes of ALI. On the one hand, iron is needed to produce reactive oxygen species (ROS) as part of the immune response to an infection; on the other hand, iron can accelerate the occurrence of ferroptosis and extend host cell damage. Iron chelation represents a novel therapeutic strategy for alleviating lung injury and improving the survival of patients with ALI. This article reviews the current knowledge of iron homeostasis, the role of iron in ALI development, and potential therapeutic targets.

Genetic regulation of iron homeostasis in sideropenic patients with mild COVID-19 disease under a new oral iron formulation: Lessons from a different perspective

Background

Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2) needs iron to replicate itself. Coronaviruses are able to upregulate Chop/Gadd153 and Arg1 genes, consequently leading to CD8 lymphocytes decrease, degradation of asparagine and decreased nitric oxide (NO), thus impairing immune response and antithrombotic functions. Little is known about regulation of genes involved in iron metabolism in paucisymptomatic patients with COVID-19 disease or in patients with iron deficiency treated with sucrosomial iron.

Methods

Whole blood was taken from the COVID-19 patients and from patients with sideropenic anemia, treated or not (control group) with iron supplementations. Enrolled patients were: affected by COVID19 under sucrosomal iron support (group A), affected by COVID-19 not under oral iron support (group B), iron deficiency not under treatment, not affected by COVID19 (control group). After RNA extraction and complementary DNA (cDNA) synthesis of Arg1, Hepcidin and Chop/Gadd153, gene expression from the 3 groups was measured by qRT-PCR. M2 macrophages were detected by cytofluorimetry using CD163 and CD14 markers.

Results

Forty patients with COVID-19 (group A), 20 patients with iron deficiency treated with sucrosomial iron (group B) and 20 patients with iron deficiency not under treatment (control group) were enrolled. In all the patients supported with oral sucrosomial iron, the gene expression of Chop, Arg1 and Hepcidin genes was lower than in sideropenic patients not supported with iron, M1 macrophages polarization and functional iron deficiency was also lower in group A and B, than observed in the control group.

Conclusions

New oral iron formulations, as sucrosomial iron, are able to influence the expression of genes like Chop and Arg1 and to influence M2 macrophage polarization mainly in the early phase of COVID-19 disease.

The Role of Ferroptosis in Acute Respiratory Distress Syndrome

Ferroptosis is a newly discovered type of regulated cell death that is different from apoptosis, necrosis and autophagy. Ferroptosis is characterized by iron-dependent lipid peroxidation, which induces cell death. Iron, lipid and amino acid metabolism is associated with ferroptosis. Ferroptosis is involved in the pathological development of various diseases, such as neurological diseases and cancer. Recent studies have shown that ferroptosis is also closely related to acute lung injury (ALI)/ acute respiratory distress syndrome (ARDS), suggesting that it can be a novel therapeutic target. This article mainly introduces the metabolic mechanism related to ferroptosis and discusses its role in ALI/ARDS to provide new ideas for the treatment of these diseases.

Mild Attenuation of the Pulmonary Inflammatory Response in a Mouse Model of Hereditary Hemochromatosis Type 4

The respiratory tract is constantly exposed to pathogens that require iron for proliferation and virulence. Pulmonary iron levels are increased in several lung diseases and associated with increased susceptibility to infections. However, regulation of lung iron homeostasis and its cross talk to pulmonary immune responses are largely unexplored. Here we investigated how increased lung iron levels affect the early pulmonary inflammatory response. We induced acute local pulmonary inflammation via aerosolized LPS in a mouse model of hereditary hemochromatosis type 4 (Slc40a1 ^C326S/C326S), which is hallmarked by systemic and pulmonary iron accumulation, specifically in alveolar macrophages. We show that Slc40a1 ^C326S/C326S mice display a mild attenuation in the LPS-induced pulmonary inflammatory response, with a reduced upregulation of some pro-inflammatory cytokines and chemokines. Despite mildly reduced cytokine levels, there is no short-term impairment in the recruitment of neutrophils into the bronchoalveolar space. These data suggest that increased pulmonary iron levels do not strongly alter the acute inflammatory response of the lung.