Iron homeostasis governs erythroid phenotype in polycythemia vera.

Polycythemia vera (PV) is a myeloproliferative neoplasm driven by activating mutations in JAK2 that result in unrestrained erythrocyte production, increasing patients' hematocrit and hemoglobin concentrations, placing them at risk of life-threatening thrombotic events. Our genome-wide association study of 440 PV cases and 403 351 controls using UK Biobank data showed that single nucleotide polymorphisms in HFE known to cause hemochromatosis are highly associated with PV diagnosis, linking iron regulation to PV. Analysis of the FinnGen dataset independently confirmed overrepresentation of homozygous HFE variants in patients with PV. HFE influences the expression of hepcidin, the master regulator of systemic iron homeostasis. Through genetic dissection of mouse models of PV, we show that the PV erythroid phenotype is directly linked to hepcidin expression: endogenous hepcidin upregulation alleviates erythroid disease whereas hepcidin ablation worsens it. Furthermore, we demonstrate that in PV, hepcidin is not regulated by expanded erythropoiesis but is likely governed by inflammatory cytokines signaling via GP130-coupled receptors. These findings have important implications for understanding the pathophysiology of PV and offer new therapeutic strategies for this disease.

Endothelial Caspase-8 prevents fatal necroptotic hemorrhage caused by commensal bacteria.

Caspase-8 transduces signals from death receptor ligands, such as tumor necrosis factor, to drive potent responses including inflammation, cell proliferation or cell death. This is a developmentally essential function because in utero deletion of endothelial Caspase-8 causes systemic circulatory collapse during embryogenesis. Whether endothelial Caspase-8 is also required for cardiovascular patency during adulthood was unknown. To address this question, we used an inducible Cre recombinase system to delete endothelial Casp8 in 6-week-old conditionally gene-targeted mice. Extensive whole body vascular gene targeting was confirmed, yet the dominant phenotype was fatal hemorrhagic lesions exclusively within the small intestine. The emergence of these intestinal lesions was not a maladaptive immune response to endothelial Caspase-8-deficiency, but instead relied upon aberrant Toll-like receptor sensing of microbial commensals and tumor necrosis factor receptor signaling. This lethal phenotype was prevented in compound mutant mice that lacked the necroptotic cell death effector, MLKL. Thus, distinct from its systemic role during embryogenesis, our data show that dysregulated microbial- and death receptor-signaling uniquely culminate in the adult mouse small intestine to unleash MLKL-dependent necroptotic hemorrhage after loss of endothelial Caspase-8. These data support a critical role for Caspase-8 in preserving gut vascular integrity in the face of microbial commensals.

Benefits and Risks of Iron Interventions in Infants in Rural Bangladesh.

BACKGROUND: Universal provision of iron supplements (drops or syrup) or multiple micronutrient powders to young children in low-to-middle-income countries where anemia is prevalent is recommended by the World Health Organization and widely implemented. The functional benefits and safety of these interventions are unclear. METHODS: We conducted a three-group, double-blind, double-dummy, individually randomized, placebo-controlled trial to assess the immediate and medium-term benefits and risks of 3 months of daily supplementation with iron syrup or iron-containing multiple micronutrient powders, as compared with placebo, in 8-month-old children in rural Bangladesh. The primary outcome was cognitive development, as assessed by the cognitive composite score on the Bayley Scales of Infant and Toddler Development, third edition, immediately after completion of the assigned 3-month regimen; scores range from 55 to 145, with higher scores indicating better cognitive performance. Secondary outcomes included the cognitive composite score at 9 months after completion of the assigned regimen; behavioral, language, and motor development, as well as growth and hematologic markers, immediately after completion and at 9 months after completion; and safety. RESULTS: We randomly assigned 3300 infants to receive iron syrup (1101 infants), multiple micronutrient powders (1099), or placebo (1100) daily. After completion of the assigned 3-month regimen, no apparent effect on the cognitive composite score was observed with iron syrup as compared with placebo (mean between-group difference in change in score from baseline, -0.30 points; 95% confidence interval [CI], -1.08 to 0.48) or with multiple micronutrient powders as compared with placebo (mean between-group difference in change in score from baseline, 0.23 points; 95% CI, -0.55 to 1.00). No apparent effect on any other developmental or growth outcome was observed immediately after completion of the assigned regimen or at 9 months after completion. At 9 months after completion of the assigned regimen, the prevalences of anemia, iron deficiency, and iron deficiency anemia increased in all three trial groups but remained lower among the children who received iron syrup or multiple micronutrient powders than among those who received placebo. The risk of serious adverse events and incidence of symptoms of infection were similar in the three trial groups. CONCLUSIONS: In this trial involving infants in Bangladesh, 3 months of daily supplementation with iron syrup or multiple micronutrient powders did not appear to have an effect on child development or other functional outcomes as compared with placebo. (Funded by the National Health and Medical Research Council of Australia; BRISC Australian New Zealand Clinical Trials Registry number, ACTRN12617000660381.).

Immediate impact of stay-at-home orders to control COVID-19 transmission on socioeconomic conditions, food insecurity, mental health, and intimate partner violence in Bangladeshi women and their families: an interrupted time series.

BACKGROUND: Stay-at-home orders (lockdowns) have been deployed globally to control COVID-19 transmission, and might impair economic conditions and mental health, and exacerbate risk of food insecurity and intimate partner violence. The effect of lockdowns in low-income and middle-income countries must be understood to ensure safe deployment of these interventions in less affluent settings. We aimed to determine the immediate impact of COVID-19 lockdown orders on women and their families in rural Bangladesh. METHODS: An interrupted time series was used to compare data collected from families in Rupganj upazila, rural Bangladesh (randomly selected from participants in a randomised controlled trial), on income, food security, and mental health a median of 1 year and 2 years before the COVID-19 pandemic to data collected during the lockdown. We also assessed women's experiences of intimate partner violence during the pandemic. RESULTS: Between May 19 and June 18, 2020, we randomly selected and invited the mothers of 3016 children to participate in the study, 2424 of whom provided consent. 2414 (99·9%, 95% CI 99·6-99·9) of 2417 mothers were aware of, and adhering to, the stay-at-home advice. 2321 (96·0%, 95·2-96·7) of 2417 mothers reported a reduction in paid work for the family. Median monthly family income fell from US$212 at baseline to $59 during lockdown, and the proportion of families earning less than $1·90 per day rose from five (0·2%, 0·0-0·5) of 2422 to 992 (47·3%, 45·2-49·5) of 2096 (p<0·0001 comparing baseline with lockdown period). Before the pandemic, 136 (5·6%, 4·7-6·6) of 2420 and 65 (2·7%, 2·1-3·4) of 2420 families experienced moderate and severe food insecurity, respectively. This increased to 881 (36·5%, 34·5-38·4) of 2417 and 371 (15·3%, 13·9-16·8) of 2417 during the lockdown; the number of families experiencing any level of food insecurity increased by 51·7% (48·1-55·4; p<0·0001). Mothers' depression and anxiety symptoms increased during the lockdown. Among women experiencing emotional or moderate physical violence, over half reported it had increased since the lockdown. INTERPRETATION: COVID-19 lockdowns present significant economic, psychosocial, and physical risks to the wellbeing of women and their families across economic strata in rural Bangladesh. Beyond supporting only the most socioeconomically deprived, support is needed for all affected families. FUNDING: National Health and Medical Research Council, Australia.

Balancing Safety and Potential for Impact in Universal Iron Interventions.

Almost 300 million children under 5 years of age are anemic worldwide. International policymakers recommend universal distribution of iron-based interventions - either iron supplements or iron-containing multiple micronutrient powders - to alleviate the burden of anemia in young children. When considering whether to implement universal iron interventions, it is essential to balance the putative benefits with possible risks. The key rationale for deploying universal iron interventions to reduce anemia in young children is to improve development, growth, and well-being. While plausible, few randomized controlled trials (RCTs) of iron interventions have carefully assessed these outcomes and there is currently inadequate evidence to support the hypothesis that universal iron interventions provide benefits on functional child health outcomes. Conversely, several important RCTs have found that when iron interventions are given to all children in a population, they may increase infection risk. Other possible risks of iron interventions have not yet been extensively described but include a risk of iron overdose and long-term iron loading in high-risk individuals. Identifying whether these interventions provide a net benefit or harm to populations is challenging. Until the quality of evidence for benefits improves, implementation of universal iron interventions in young children should be undertaken with caution.