Iron deficiency protects against severe Plasmodium falciparum malaria and death in young children

Longitudinal changes in iron homeostasis in human experimental and clinical malaria

BACKGROUND

The interaction between iron status and malaria is incompletely understood. We evaluated longitudinal changes in iron homeostasis in volunteers enrolled in malaria volunteer infection studies (VIS) and in Malaysian patients with falciparum and vivax malaria.

METHODS

We retrieved data and samples from 55 participants (19 female) enrolled in malaria VIS, and 171 patients (45 female) with malaria and 30 healthy controls (13 female) enrolled in clinical studies in Malaysia. Ferritin, hepcidin, erythropoietin, and soluble transferrin receptor (sTfR) were measured by ELISA.

FINDINGS

In the VIS, participants' parasitaemia was correlated with baseline mean corpuscular volume (MCV), but not iron status (ferritin, hepcidin or sTfR). Ferritin, hepcidin and sTfR all increased during the VIS. Ferritin and hepcidin normalised by day 28, while sTfR remained elevated. In VIS participants, baseline ferritin was associated with post-treatment increases in liver transaminase levels. In Malaysian patients with malaria, hepcidin and ferritin were elevated on admission compared to healthy controls, while sTfR increased following admission. By day 28, hepcidin had normalised; however, ferritin and sTfR both remained elevated.

INTERPRETATION

Our findings demonstrate that parasitaemia is associated with an individual's MCV rather than iron status. The persistent elevation in sTfR 4 weeks post-infection in both malaria VIS and clinical malaria may reflect a causal link between malaria and iron deficiency.

FUNDING

National Health and Medical Research Council (Program Grant 1037304, Project Grants 1045156 and 1156809; Investigator Grants 2016792 to BEB, 2016396 to JCM, 2017436 to MJG); US National Institute of Health (R01-AI116472-03); Malaysian Ministry of Health (BP00500420).

Association between asymptomatic Plasmodium falciparum malaria infection, anaemia and mean corpuscular volume of school children in the Volta Region of Ghana

Background

Although, several studies have reported abnormal Mean Corpuscular Volume (MCV) values and anaemia associated with malaria infections with a focus on Plasmodium falciparum among patients with complicated and uncomplicated malaria, none has looked at the association with asymptomatic malaria. This study aimed to assess this association.

Methods

We conducted a cross-sectional study using 3 mL of blood samples from 549 children aged 5-17 years attending 5 schools selected in the Volta Region. Semi-structured questionnaires were administered to the children to obtain demographic data. Blood samples were collected to estimate the children's full blood count (FBC) and malaria status. Data obtained were analysed using STATA 15 software. P-values of less than 0.05 were considered statistically significant.

Results

Most of the children in this study (49.9%) had normal MCV (81.3-91.3 fL) with an overall malaria prevalence of 55.6 % (95% CI: 51.3-59.8) and anaemia prevalence of 48.6% (95% CI 44.4-52.9). Most anaemic children had normal MCV (81.3-91.3 fL) (49.8, 95% CI 43.7-56.0). The predicted probability of malaria was highly likely among children with normal MCV (81.3-91.3 fL) but with high variability and uncertainty among those with low MCV (<81.3 fL) and high MCV (>91.3 fL).

Conclusion

This study shows a reduced predicted probability of malaria among children with low and high MCV, playing a protective function against malaria. Further studies are required to elucidate the interaction.

Naturally acquired immunity to Plasmodium pitheci in Bornean orangutans (Pongo pygmaeus)

Naturally acquired immunity to the different types of malaria in humans occurs in areas of endemic transmission and results in asymptomatic infection of peripheral blood. The current study examined the possibility of naturally acquired immunity in Bornean orangutans, Pongo pygmaeus, exposed to endemic Plasmodium pitheci malaria. A total of 2140 peripheral blood samples were collected between January 2017 and December 2022 from a cohort of 135 orangutans housed at a natural forested Rescue and Rehabilitation Centre in West Kalimantan, Indonesia. Each individual was observed for an average of 4.3 years during the study period. Blood samples were examined by microscopy and polymerase chain reaction for the presence of plasmodial parasites. Infection rates and parasitaemia levels were measured among age groups and all 20 documented clinical malaria cases were reviewed to estimate the incidence of illness and risk ratios among age groups. A case group of all 17 individuals that had experienced clinical malaria and a control group of 34 individuals having an event of >2000 parasites μL−1 blood but with no outward or clinical sign of illness were studied. Immature orangutans had higher-grade and more frequent parasitaemia events, but mature individuals were more likely to suffer from clinical malaria than juveniles. The case orangutans having patent clinical malaria were 256 times more likely to have had no parasitaemia event in the prior year relative to asymptomatic control orangutans. The findings are consistent with rapidly acquired immunity to P. pitheci illness among orangutans that wanes without re-exposure to the pathogen.

Higher platelet counts and platelet factors are associated with a reduction in Plasmodium falciparum parasite density in young Malian children

OBJECTIVES

The association between thrombocytopenia and parasite density or disease severity is described in numerous studies. In recent years, several studies described the protective role of platelets in directly killing Plasmodium parasites, mediated by platelet factor 4 (PF4) binding to Duffy antigen. This study aimed to evaluate the protective role of platelets in young children who are Duffy antigen-negative, such as those in sub-Saharan Africa.

METHODS

A zero-inflated negative binomial model was used to relate platelet count and parasite density data collected in a longitudinal birth cohort. Platelet factors were measured by enzyme-linked immunosorbent assay in samples collected from malaria-infected children who participated in a cross-sectional study.

RESULTS

We described that an increase of 10,000 platelets/μl was associated with a 2.76% reduction in parasite count. Increasing levels of PF4 and CXCL7 levels were also significantly associated with a reduction in parasite count.

CONCLUSIONS

Platelets play a protective role in reducing parasite burden in Duffy-negative children, possibly mediated through activation of the innate immune system.

Nutrition in chronic inflammatory conditions: Bypassing the mucosal block for micronutrients

Nutritional Immunity is one of the most ancient innate immune responses, during which the body can restrict nutrients availability to pathogens and restricts their uptake by the gut mucosa (mucosal block). Though this can be a beneficial strategy during infection, it also is associated with non-communicable diseases-where the pathogen is missing; leading to increased morbidity and mortality as micronutritional uptake and distribution in the body is hindered. Here, we discuss the acute immune response in respect to nutrients, the opposing nutritional demands of regulatory and inflammatory cells and particularly focus on some nutrients linked with inflammation such as iron, vitamins A, Bs, C, and other antioxidants. We propose that while the absorption of certain micronutrients is hindered during inflammation, the dietary lymph path remains available. As such, several clinical trials investigated the role of the lymphatic system during protein absorption, following a ketogenic diet and an increased intake of antioxidants, vitamins, and minerals, in reducing inflammation and ameliorating disease.

Longitudinal changes in iron homeostasis in human experimental and clinical malaria

Background

The interaction between iron deficiency and malaria is incompletely understood. We evaluated longitudinal changes in iron homeostasis in volunteers enrolled in malaria volunteer infection studies (VIS) and in Malaysian patients with falciparum and vivax malaria.

Methods

We retrieved samples and associated data from 55 participants enrolled in malaria VIS, and 171 malaria patients and 30 healthy controls enrolled in clinical studies in Malaysia. Ferritin, hepcidin, erythropoietin, and soluble transferrin receptor (sTfR) were measured by ELISA.

Results

In the VIS, participants' parasitaemia was correlated with baseline mean corpuscular volume (MCV), but not iron status (ferritin, hepcidin or sTfR). Ferritin, hepcidin and sTfR all increased during the VIS. Ferritin and hepcidin normalised by day 28, while sTfR remained elevated. In VIS participants, baseline iron status (ferritin) was associated with post-treatment increases in liver transaminase levels. In Malaysian malaria patients, hepcidin and ferritin were elevated on admission compared to healthy controls, while sTfR increased following admission. Hepcidin normalised by day 28; however, ferritin and sTfR both remained elevated 4 weeks following admission.

Conclusion

Our findings demonstrate that parasitaemia is associated with an individual's MCV rather than iron status. The persistent elevation in sTfR 4 weeks post-infection in both malaria VIS and clinical malaria may reflect a causal link between malaria and iron deficiency.

Plasmodium yoelii iron transporter PyDMT1 interacts with host ferritin and is required in full activity for malarial pathogenesis

BACKGROUND

The rapid reproduction of malaria parasites requires proper iron uptake. However, the process of iron absorption by parasites is rarely studied. Divalent metal transporter (DMT1) is a critical iron transporter responsible for uptaking iron. A homolog of human DMT1 exists in the malaria parasite genome, which in Plasmodium yoelii is hereafter named PyDMT1.

RESULTS

PyDMT1 knockout appears to be lethal. Surprisingly, despite dwelling in an iron-rich environment, the parasite cannot afford to lose even partial expression of PyDMT1; PyDMT1 hypomorphs were associated with severe growth defects and quick loss of pathogenicity. Iron supplementation could completely suppress the defect of the PyDMT1 hypomorph during in vitro culturing. Genetic manipulation through host ferritin (Fth1) knockout to increase intracellular iron levels enforced significant growth inhibition in vivo on the normal parasites but not the mutant. In vitro culturing with isolated ferritin knockout mouse erythrocytes completely rescued PyDMT1-hypomorph parasites.

CONCLUSION

A critical iron requirement of malaria parasites at the blood stage as mediated by this newly identified iron importer PyDMT1, and the iron homeostasis in malarial parasites is finely tuned. Tipping the iron balance between the parasite and host will efficiently kill the pathogenicity of the parasite. Lastly, PyDMT1 hypomorph parasites were less sensitive to the action of artemisinin.

Biology of Anemia: A Public Health Perspective

Our goal is to present recent progress in understanding the biological mechanisms underlying anemia from a public health perspective. We describe important advances in understanding common causes of anemia and their interactions, including iron deficiency (ID), lack of other micronutrients, infection, inflammation, and genetic conditions. ID develops if the iron circulating in the blood cannot provide the amounts required for red blood cell production and tissue needs. ID anemia develops as iron-limited red blood cell production fails to maintain the hemoglobin concentration above the threshold used to define anemia. Globally, absolute ID (absent or reduced body iron stores that do not meet the need for iron of an individual but may respond to iron supplementation) contributes to only a limited proportion of anemia. Functional ID (adequate or increased iron stores that cannot meet the need for iron because of the effects of infection or inflammation and does not respond to iron supplementation) is frequently responsible for anemia in low- and middle-income countries. Absolute and functional ID may coexist. We highlight continued improvement in understanding the roles of infections and inflammation in causing a large proportion of anemia. Deficiencies of nutrients other than iron are less common but important in some settings. The importance of genetic conditions as causes of anemia depends upon the specific inherited red blood cell abnormalities and their prevalence in the settings examined. From a public health perspective, each setting has a distinctive composition of components underlying the common causes of anemia. We emphasize the coincidence between regions with a high prevalence of anemia attributed to ID (both absolute and functional), those with endemic infections, and those with widespread genetic conditions affecting red blood cells, especially in sub-Saharan Africa and regions in Asia and Oceania.

Safe and effective delivery of supplemental iron to healthy adults: a two-phase, randomized, double-blind trial - the safe iron study

Introduction

The safety of novel forms of iron in healthy, iron-replete adults as might occur if used in population-based iron supplementation programs was examined. We tested the hypotheses that supplementation with nanoparticulate iron hydroxide adipate tartrate (IHAT), an iron-enriched Aspergillus oryzae product (ASP), or ferrous sulphate heptahydrate (FS) are safe as indicated by erythrocyte susceptibility to malarial infection, bacterial proliferation, and gut inflammation. Responses to FS administered daily or weekly, and with or without other micronutrients were compared.

Methods

Two phases of randomized, double-blinded trials were conducted in Boston, MA. Phase I randomized 160 volunteers to six treatments: placebo, IHAT, ASP, FS, and FS plus a micronutrient powder (MNP) administrated daily at 60 mg Fe/day; and FS administered as a single weekly dose of 420 mg Fe. Phase II randomized 86 volunteers to IHAT, ASP, or FS administered at 120 mg Fe/day. Completing these phases were 151 and 77 participants, respectively. The study was powered to detect effects on primary endpoints: susceptibility of participant erythrocytes to infection by Plasmodium falciparum, the proliferation potential of selected pathogenic bacteria in sera, and markers of gut inflammation. Secondary endpoints for which the study was not powered included indicators of iron status and gastrointestinal symptoms.

Results

Supplementation with any form of iron did not affect any primary endpoint. In Phase I, the frequency of gastrointestinal symptoms associated with FS was unaffected by dosing with MNP or weekly administration; but participants taking IHAT more frequently reported abdominal pain (27%, p < 0.008) and nausea (4%, p = 0.009) than those taking FS, while those taking ASP more frequently reported nausea (8%, p = 0.009). Surprisingly, only 9% of participants taking IHAT at 120 mg Fe/day (Phase II) reported abdominal pain and no other group reported that symptom.

Discussion

With respect to the primary endpoints, few differences were found when comparing these forms of iron, indicating that 28 days of 60 or 120 mg/day of IHAT, ASP, or FS may be safe for healthy, iron-replete adults. With respect to other endpoints, subjects receiving IHAT more frequently reported abdominal pain and nausea, suggesting the need for further study.

Clinical Trial Registration

ClinicalTrials.gov, NCT03212677; registered: 11 July 2017.

Cellular iron governs the host response to malaria

Malaria and iron deficiency are major global health problems with extensive epidemiological overlap. Iron deficiency-induced anaemia can protect the host from malaria by limiting parasite growth. On the other hand, iron deficiency can significantly disrupt immune cell function. However, the impact of host cell iron scarcity beyond anaemia remains elusive in malaria. To address this, we employed a transgenic mouse model carrying a mutation in the transferrin receptor (TfrcY20H/Y20H), which limits the ability of cells to internalise iron from plasma. At homeostasis TfrcY20H/Y20H mice appear healthy and are not anaemic. However, TfrcY20H/Y20H mice infected with Plasmodium chabaudi chabaudi AS showed significantly higher peak parasitaemia and body weight loss. We found that TfrcY20H/Y20H mice displayed a similar trajectory of malaria-induced anaemia as wild-type mice, and elevated circulating iron did not increase peak parasitaemia. Instead, P. chabaudi infected TfrcY20H/Y20H mice had an impaired innate and adaptive immune response, marked by decreased cell proliferation and cytokine production. Moreover, we demonstrated that these immune cell impairments were cell-intrinsic, as ex vivo iron supplementation fully recovered CD4+ T cell and B cell function. Despite the inhibited immune response and increased parasitaemia, TfrcY20H/Y20H mice displayed mitigated liver damage, characterised by decreased parasite sequestration in the liver and an attenuated hepatic immune response. Together, these results show that host cell iron scarcity inhibits the immune response but prevents excessive hepatic tissue damage during malaria infection. These divergent effects shed light on the role of iron in the complex balance between protection and pathology in malaria.

The effects of intracellular iron availability on the outcome of Toxoplasma gondii infection in mice

Toxoplasma gondii (T. gondii) is a parasite that obtains the iron it needs for its own metabolism from the host-cell iron pool. In this work, we aimed to investigate if iron supplementation or deficiency affected the course of T. gondii infection. Eighty mice were divided into four groups, each with 20 animals: Group (I): Uninfected control group. Group (II): Infected control group: injected with Phosphate buffered saline. Group (III): Infected group: received iron sucrose treatment. Group (IV): Infected group: treated with deferoxamine. Quantitative PCR studies were performed on days 3 and 8 post-infection to detect the expression of iron metabolism genes (hamp and ferroprotin) and immune-histochemical analysis to study the percentage of TNF-α and TGF-β tissue expression. Iron supplementation induced progressions of infection evident by increased tissue expression of pro-inflammatory cytokine TNF-α and downregulation of TGF-β which is mostly linked to suppression of the inflammatory process caused by T. gondii. Increased expression of TGF-β and decreased expression of TNF-α was noticed when iron deprivation occurred. On day 3, we noticed increased expression in the hamp gene with iron supplementation while it decreases when the iron supply is low. On the contrary, iron deficiency increased ferroprotin gene expression whereas supplementing decreased it. On day 8, the level of expression of these genes returned to normal levels. These observations document the potential role of iron in controlling toxoplasmosis infection and indicate that the transcription of hamp and ferroprotin in T. gondii-infected cells appears to be regulated by a sophisticated indirect mechanism.

Universal iron supplementation: the best strategy to tackle childhood anaemia in malaria-endemic countries?

Iron deficiency presents a major public health concern in many malaria-endemic regions, and both conditions affect young children most severely. Daily iron supplementation is the standard public health intervention recommended to alleviate rates of iron deficiency in children, but there is controversy over whether universal supplementation could increase the incidence and severity of malaria infection. Current evidence suggests that iron supplementation of deficient individuals is safe and effective in high-transmission settings when accompanied by malaria prevention strategies. However, low-resource settings often struggle to effectively control the spread of malaria, and it remains unclear whether supplementation of iron replete individuals could increase their risk of malaria and other infections. This review explores the evidence for and against universal iron supplementation programmes, and alternative strategies that could be used to alleviate iron deficiency in malaria-endemic areas, while minimising potential harm.

Histidine-rich protein II nanoparticle delivery of heme iron load drives endothelial inflammation in cerebral malaria

Histidine-rich protein II (HRPII) is secreted by Plasmodium falciparum during the blood stage of malaria infection. High plasma levels of HRPII are associated with cerebral malaria, a severe and highly fatal complication of malaria. HRPII has been shown to induce vascular leakage, the hallmark of cerebral malaria, in blood-brain barrier (BBB) and animal models. We have discovered an important mechanism for BBB disruption that is driven by unique features of HRPII. By characterizing serum from infected patients and HRPII produced by P. falciparum parasites in culture, we found that HRPII exists in large multimeric particles of 14 polypeptides that are richly laden with up to 700 hemes per particle. Heme loading of HRPII is required for efficient binding and internalization via caveolin-mediated endocytosis in hCMEC/D3 cerebral microvascular endothelial cells. Upon acidification of endolysosomes, two-thirds of the hemes are released from acid-labile binding sites and metabolized by heme oxygenase 1, generating ferric iron and reactive oxygen species. Subsequent activation of the NLRP3 inflammasome and IL-1β secretion resulted in endothelial leakage. Inhibition of these pathways with heme sequestration, iron chelation, or anti-inflammatory drugs protected the integrity of the BBB culture model from HRPII:heme. Increased cerebral vascular permeability was seen after injection of young mice with heme-loaded HRPII (HRPII:heme) but not with heme-depleted HRPII. We propose that during severe malaria infection, HRPII:heme nanoparticles in the bloodstream deliver an overwhelming iron load to endothelial cells to cause vascular inflammation and edema. Disrupting this process is an opportunity for targeted adjunctive therapies to reduce the morbidity and mortality of cerebral malaria.

Nutritional Aspects of Iron in Health and Disease

Dietary iron assimilation is critical for health and essential to prevent iron-deficient states and related comorbidities, such as anemia. The bioavailability of iron is generally low, while its absorption and metabolism are tightly controlled to satisfy metabolic needs and prevent toxicity of excessive iron accumulation. Iron entry into the bloodstream is limited by hepcidin, the iron regulatory hormone. Hepcidin deficiency due to loss-of-function mutations in upstream gene regulators causes hereditary hemochromatosis, an endocrine disorder of iron overload characterized by chronic hyperabsorption of dietary iron, with deleterious clinical complications if untreated. The impact of high dietary iron intake and elevated body iron stores in the general population is not well understood. Herein, we summarize epidemiological data suggesting that a high intake of heme iron, which is abundant in meat products, poses a risk factor for metabolic syndrome pathologies, cardiovascular diseases, and some cancers. We discuss the clinical relevance and potential limitations of data from cohort studies, as well as the need to establish causality and elucidate molecular mechanisms.

Lack of iron, zinc, and vitamins as a contributor to the etiology of atopic diseases

Micronutritional deficiencies are common in atopic children suffering from atopic dermatitis, food allergy, rhinitis, and asthma. A lack of iron, in particular, may impact immune activation with prolonged deficiencies of iron, zinc, vitamin A, and vitamin D associated with a Th2 signature, maturation of macrophages and dendritic cells (DCs), and the generation of IgE antibodies. In contrast, the sufficiency of these micronutrients establishes immune resilience, promotion of regulatory cells, and tolerance induction. As micronutritional deficiencies mimic an infection, the body's innate response is to limit access to these nutrients and also impede their dietary uptake. Here, we summarize our current understanding of the physiological function of iron, zinc, and vitamins A and D in relation to immune cells and the clinical consequences of deficiencies in these important nutrients, especially in the perinatal period. Improved dietary uptake of iron is achieved by vitamin C, vitamin A, and whey compounds, whereas zinc bioavailability improves through citrates and proteins. The addition of oil is essential for the dietary uptake of beta-carotene and vitamin D. As for vitamin D, the major source comes via sun exposure and only a small amount is consumed via diet, which should be factored into clinical nutritional studies. We summarize the prevalence of micronutritional deficiencies of iron, zinc, and vitamins in the pediatric population as well as nutritional intervention studies on atopic diseases with whole food, food components, and micronutrients. Dietary uptake via the lymphatic route seems promising and is associated with a lower atopy risk and symptom amelioration. This review provides useful information for clinical studies and concludes/emphasizes that a healthy, varied diet containing dairy products, fish, nuts, fruits, and vegetables as well as supplementing foods or supplementation with micronutrients as needed is essential to combat the atopic march.

TMPRSS6 rs855791 polymorphism is associated with iron deficiency in a cohort of Sri Lankan pregnant women

Background

Hepcidin is the key regulator of systemic iron homeostasis and is downregulated by matriptase 2 (MT2), a protease encoded by TMPRSS6 gene. In the presence of low iron levels, MT2 cleaves membrane-bound hemojuvelin (HJV), causing a negative regulation of hepcidin at the gene level, and restores iron balance. rs855791T > C, a missense variant in the catalytic domain of MT2, causes valine to alanine change at 736 position. The current study aimed to investigate the association of TMPRSS6 rs855791 on iron status among a cohort of pregnant women in Sri Lanka and to predict the possible molecular mechanisms.

Methods

The study was conducted among 73 pregnant women at ≤ 12 weeks of gestation. Iron deficiency was defined as serum ferritin < 30 μg/L after adjusting for inflammation. rs855791 was genotyped with a PCR–RFLP, and its association with iron deficiency was analyzed using binary logistic regression. Docking of HJV with MT2 protein encoded by the two rs855791 alleles was undertaken in silico to predict the molecular mechanism of the observed associations.

Results

The majority of the study population (70%) were iron deficient. Among the subjects, T allele was prevalent in the iron deficient group with a frequency of 61.8%, with a nearly twofold enhanced risk for iron deficiency (OR = 2.566, 95%CI; P = 0.011). For TT genotype, the risk of iron deficiency was nearly sixfold (OR = 5.867; 95%CI; P = 0.023). According to the in silico analysis, MT2 736A and HJV complex is more stable with an interface energy of − 7.934 kJ/mol compared to the MT2 736 V and HJV complex which generates an interface energy of − 4.689 kJ/mol.

Conclusion

The current study suggests that the iron regulatory effect of rs855791 of TMPRSS6 is brought about by the differences in thermodynamic stability of the two protein complexes made by MT2 and HJV proteins. The prevalence of iron deficiency observed among Sri Lankan pregnant women may be an interplay between the prevalence of rs855791 T allele and the low dietary iron intake.

Iron Dyshomeostasis in COVID-19: Biomarkers Reveal a Functional Link to 5-Lipoxygenase Activation

Coronavirus disease 2019 (COVID-19) is characterized by a broad spectrum of clinical symptoms. After acute infection, some subjects develop a post-COVID-19 syndrome known as long-COVID. This study aims to recognize the molecular and functional mechanisms that occur in COVID-19 and long-COVID patients and identify useful biomarkers for the management of patients with COVID-19 and long-COVID. Here, we profiled the response to COVID-19 by performing a proteomic analysis of lymphocytes isolated from patients. We identified significant changes in proteins involved in iron metabolism using different biochemical analyses, considering ceruloplasmin (Cp), transferrin (Tf), hemopexin (HPX), lipocalin 2 (LCN2), and superoxide dismutase 1 (SOD1). Moreover, our results show an activation of 5-lipoxygenase (5-LOX) in COVID-19 and in long-COVID possibly through an iron-dependent post-translational mechanism. Furthermore, this work defines leukotriene B4 (LTB4) and lipocalin 2 (LCN2) as possible markers of COVID-19 and long-COVID and suggests novel opportunities for prevention and treatment.

Rapid diagnosis of malaria by chemometric peak-free LIBS of trace biometals in blood

Laser Induced Breakdown Spectroscopy (LIBS) trace atomic species of diseased biofluids are subtle (peak-free) in complex spectra. Trace analysis requires a considerable push in analytical strategy. Enabling LIBS with chemometrics can help identify, extract, analyze and interpret the trace species' spectral signatures to give an insight on the biophysiological status of the bodies from which the biofluids originate. We report on the trace quantitative performance of peak-free LIBS enabled by chemometrics modelling using principal components analysis (PCA) for direct artificial neural network (ANN)-based analysis of Cu, Zn, Fe and Mg in Plasmodium falciparum-infected blood in the context of rapid spectral diagnosis of malaria utilizing the biometals as the disease biomarkers. Only one standard is required in this method-to delineate the analyte spectral regions (feature selection) and to test for accuracy. Based on the alteration of the biometal levels and their multivariate and correlational patterns in cultured blood, peripheral finger blood drops dried directly on Nucleopore membrane filters was accurately discriminated as either malaria-infected or healthy. Further the morphological evolution of Plasmodium was accurately predicted using spectral features of the biometals wherein high negative correlations between Fe (- 0.775) and Zn (- 0.881) and high positive correlations between Cu (0.892) and Mg (0.805) with parasitemia were observed. During the first 96 h of malaria infection Cu increases profoundly (from 328 to 1999 ppb) while Fe, Zn and Mg decrease (from 1206 to 674 ppb), (from 1523 to 499 ppb) and (from 23,880 to 19,573 ppb) respectively. Compared with healthy, Plasmodium falciparum-infected blood has high Cu but low levels of Fe, Zn and Mg. Cu and Zn are highly (≥ 0.9) positively correlated while Fe and Cu as well as Zn and Cu are highly (≥ 0.9) negatively correlated. Chemometric peak-free LIBS showed the potential for direct rapid malaria diagnostics in blood based on the levels, alterations and multivariate associations of the trace biometals which are used as biomarkers of the disease.

Iron metabolism: pathways and proteins in homeostasis

Iron is essential to human survival. The biological role and trafficking of this trace essential inorganic element which is also a potential toxin is constantly being researched and unfolded. Vital for oxygen transport, DNA synthesis, electron transport, neurotransmitter biosynthesis and present in numerous other heme and non-heme enzymes the physiological roles are immense. Understanding the molecules and pathways that regulate this essential element at systemic and cellular levels are of importance in improving therapeutic strategies for iron related disorders. This review highlights the progress in understanding the metabolism and trafficking of iron along with the pathophysiology of iron related disorders.

Plasmodium pitheci malaria in Bornean orang-utans at a rehabilitation centre in West Kalimantan, Indonesia

BACKGROUND

Plasmodial species naturally infecting orang-utans, Plasmodium pitheci and Plasmodium silvaticum, have been rarely described and reportedly cause relatively benign infections. Orang-utans at Rescue Rehabilitation Centres (RRC) across the orang-utan natural range suffer from malaria illness. However, the species involved and clinical pathology of this illness have not been described in a systematic manner. The objective of the present study was to identify the Plasmodium species infecting orang-utans under our care, define the frequency and character of malaria illness among the infected, and establish criteria for successful diagnosis and treatment.

METHODS

During the period 2017-2021, prospective active surveillance of malaria among 131 orang-utans resident in a forested RRC in West Kalimantan (Indonesia) was conducted. A total of 1783 blood samples were analysed by microscopy and 219 by nucleic acid based (PCR) diagnostic testing. Medical records of inpatient orang-utans at the centre from 2010 to 2016 were also retrospectively analysed for instances of symptomatic malaria.

RESULTS

Active surveillance revealed 89 of 131 orang-utans were positive for malaria at least once between 2017 and 2021 (period prevalence = 68%). During that period, 14 cases (affecting 13 orang-utans) developed clinical malaria (0.027 attacks/orang-utan-year). Three other cases were found to have occurred from 2010-2016. Sick individuals presented predominantly with fever, anaemia, thrombocytopenia, and leukopenia. All had parasitaemias in excess of 4000/μL and as high as 105,000/μL, with severity of illness correlating with parasitaemia. Illness and parasitaemia quickly resolved following administration of artemisinin-combined therapies. High levels of parasitaemia also sometimes occurred in asymptomatic cases, in which case, parasitaemia cleared spontaneously.

CONCLUSIONS

This study demonstrated that P. pitheci very often infected orang-utans at this RRC. In about 14% of infected orang-utans, malaria illness occurred and ranged from moderate to severe in nature. The successful clinical management of acute pitheci malaria is described. Concerns are raised about this infection potentially posing a threat to this endangered species in the wild.

Levels of Serum Ferritin and Hepcidin in Patients with Uncomplicated Falciparum Malaria in Hodeidah, Yemen: Considerations for Assessing Iron Status

Understanding the key regulator of iron homeostasis is critical to the improvement of iron supplementation practices in malaria-endemic areas. This study aimed to determine iron indices and hepcidin (HEPC) level in patients infected with Plasmodium falciparum compared to apparently healthy, malaria-negative subjects in Hodeidah, Yemen. The study included 70 Plasmodium falciparum-infected and 20 malaria-negative adults. Blood films were examined for detection and estimation of parasitemia. Hemoglobin (Hb) level was measured using an automated hematology analyzer. Serum iron and total iron binding capacity (TIBC) were determined by spectrophotometric methods. Levels of serum ferritin (FER) and HEPC were measured by enzyme-linked immunosorbent assays. Data were stratified by sex and age. Comparable Hb levels were found in P. falciparum-infected patients and malaria-negative subjects in each sex and age group (p > 0.05). Compared to their malaria-negative counterparts, disturbed iron homeostasis in patients was evidenced by the significantly lower serum iron levels in females (p = 0.007) and those aged <25 years (p = 0.02) and the significantly higher TIBC in males (p = 0.008). Levels of serum FER and HEPC were significantly elevated in P. falciparum-infected patients compared to the corresponding malaria-negative participants (p < 0.001). Serum FER correlated positively with parasite density (p = 0.004). In conclusion, patients with uncomplicated P. falciparum in Hodeidah display elevated levels of serum HEPC and FER. Hemoglobin level may not reflect the disturbed iron homeostasis in these patients. The combined measurement of iron indices and HEPC provides comprehensive information on the iron status so that the right intervention can be chosen.

Oxidative Stress in Malaria: Potential Benefits of Antioxidant Therapy

Malaria is an infectious disease and a serious public health problem in the world, with 3.3 billion people in endemic areas in 100 countries and about 200 million new cases each year, resulting in almost 1 million deaths in 2018. Although studies look for strategies to eradicate malaria, it is necessary to know more about its pathophysiology to understand the underlying mechanisms involved, particularly the redox balance, to guarantee success in combating this disease. In this review, we addressed the involvement of oxidative stress in malaria and the potential benefits of antioxidant supplementation as an adjuvant antimalarial therapy.

Forward Genetics in Apicomplexa Biology: The Host Side of the Story

Forward genetic approaches have been widely used in parasitology and have proven their power to reveal the complexities of host-parasite interactions in an unbiased fashion. Many aspects of the parasite's biology, including the identification of virulence factors, replication determinants, antibiotic resistance genes, and other factors required for parasitic life, have been discovered using such strategies. Forward genetic approaches have also been employed to understand host resistance mechanisms to parasitic infection. Here, we will introduce and review all forward genetic approaches that have been used to identify host factors involved with Apicomplexa infections, which include classical genetic screens and QTL mapping, GWAS, ENU mutagenesis, overexpression, RNAi and CRISPR-Cas9 library screens. Collectively, these screens have improved our understanding of host resistance mechanisms, immune regulation, vaccine and drug designs for Apicomplexa parasites. We will also discuss how recent advances in molecular genetics give present opportunities to further explore host-parasite relationships.

Iron Metabolism and Immune Regulation

Iron is a critical element for living cells in terrestrial life. Although iron metabolism is strictly controlled in the body, disturbance of iron homeostasis under certain type of condition leads to innate and adaptive immune response. In innate immunity, iron regulates macrophage polarizations, neutrophils recruitment, and NK cells activity. In adaptive immunity, iron had an effect on the activation and differentiation of Th1, Th2, and Th17 and CTL, and antibody response in B cells. In this review, we focused on iron and immune regulation and listed the specific role of iron in macrophage polarization, T-cell activation, and B-cells antibody response. In addition, correlations between iron and several diseases such as cancer and aging degenerative diseases and some therapeutic strategies targeting those diseases are also discussed.

Temporal variation of planetary iron as a driver of evolution

Iron is an irreplaceable component of proteins and enzyme systems required for life. This need for iron is a well-characterized evolutionary mechanism for genetic selection. However, there is limited consideration of how iron bioavailability, initially determined by planetary accretion but fluctuating considerably at global scale over geological time frames, has shaped the biosphere. We describe influences of iron on planetary habitability from formation events >4 Gya and initiation of biochemistry from geochemistry through oxygenation of the atmosphere to current host–pathogen dynamics. By determining the iron and transition element distribution within the terrestrial planets, planetary core formation is a constraint on both the crustal composition and the longevity of surface water, hence a planet’s habitability. As such, stellar compositions, combined with metallic core-mass fraction, may be an observable characteristic of exoplanets that relates to their ability to support life. On Earth, the stepwise rise of atmospheric oxygen effectively removed gigatons of soluble ferrous iron from habitats, generating evolutionary pressures. Phagocytic, infectious, and symbiotic behaviors, dating from around the Great Oxygenation Event, refocused iron acquisition onto biotic sources, while eukaryotic multicellularity allows iron recycling within an organism. These developments allow life to more efficiently utilize a scarce but vital nutrient. Initiation of terrestrial life benefitted from the biochemical properties of abundant mantle/crustal iron, but the subsequent loss of iron bioavailability may have been an equally important driver of compensatory diversity. This latter concept may have relevance for the predicted future increase in iron deficiency across the food chain caused by elevated atmospheric CO₂.

COVID-19 Pandemic as Risk Factors for Excessive Weight Gain in Pediatrics: The Role of Changes in Nutrition Behavior. A Narrative Review

During the coronavirus disease 2019 (COVID-19) pandemic, social isolation, semi-lockdown, and "stay at home" orders were imposed upon the population in the interest of infection control. This dramatically changes the daily routine of children and adolescents, with a large impact on lifestyle and wellbeing. Children with obesity have been shown to be at a higher risk of negative lifestyle changes and weight gain during lockdown. Obesity and COVID-19 negatively affect children and adolescents' wellbeing, with adverse effects on psychophysical health, due in large part to food choices, snacking between meals, and comfort eating. Moreover, a markable decrease in physical activity levels and an increase in sedentary behavior is associated with weight gain, especially in children with excessive weight. In addition, obesity is the most common comorbidity in severe cases of COVID-19, suggesting that immune dysregulation, metabolic unbalance, inadequate nutritional status, and dysbiosis are key factors in the complex mechanistic and clinical interplay between obesity and COVID-19. This narrative review aims to describe the most up-to-date evidence on the clinical characteristics of COVID-19 in children and adolescents, focusing on the role of excessive weight and weight gain in pediatrics. The COVID-19 pandemic has taught us that nutrition education interventions, access to healthy food, as well as family nutrition counselling should be covered by pediatric services to prevent obesity, which worsens disease outcomes related to COVID-19 infection.

Micronutrient supplements can promote disruptive protozoan and fungal communities in the developing infant gut

Supplementation with micronutrients, including vitamins, iron and zinc, is a key strategy to alleviate child malnutrition. However, association of gastrointestinal disorders with iron has led to ongoing debate over their administration. To better understand their impact on gut microbiota, we analyse the bacterial, protozoal, fungal and helminth communities of stool samples collected from a subset of 80 children at 12 and 24 months of age, previously enrolled into a large cluster randomized controlled trial of micronutrient supplementation in Pakistan (ClinicalTrials.gov identifier NCT00705445). We show that while bacterial diversity is reduced in supplemented children, vitamins and iron (as well as residence in a rural setting) may promote colonization with distinct protozoa and mucormycetes, whereas the addition of zinc appears to ameliorate this effect. We suggest that the risks and benefits of micronutrient interventions may depend on eukaryotic communities, potentially exacerbated by exposure to a rural setting. Larger studies are needed to evaluate the clinical significance of these findings and their impact on health outcomes.

Prevalence, density and predictors of malaria parasitaemia among ill young Nigerian infants

INTRODUCTION

infants in the first six months of life are relatively protected from malaria. Emerging reports from endemic regions however are showing increasing malaria susceptibility in this age group. This study set out to determine the prevalence, parasite density and predictive factors for malaria parasitaemia in ill young infants at the Wesley Guild Hospital (WGH), Ilesa, Nigeria.

METHODS

ill infants aged one to six months were consecutively recruited over an 11-month period in a hospital based cross-sectional study. History of illness, sociodemographic and perinatal history were obtained; clinical examination and results of venous blood for thick and thin film malaria parasite examinations were recorded and analyzed.

RESULTS

the mean (SD) age of the 350 infants was 3.4 (1.6) months with male: female (M: F) of 1.2: 1. The prevalence of malaria parasitaemia (all plasmodium falciparum) was 19.1% while parasite density ranged from 24.0 to 400,000 parasites/µl, median (IQR) 900 (250-4,588)/µl. Sixteen (4.6%) had heavy malaria parasitaemia (>5000/µl). Low social class (OR=2.457; 95%CI 1.404-4.300; p=0.002), suboptimal antenatal care (OR=2.226; 95%CI 1.096-4.522; p=0.027), low birth weight infants (OR=4.818; 95%CI 2.317-10.018; p=<0.001) and injudicious use of haematinics (OR=3.192; 95%CI1.731-5.886; p=<0.001) were predictors of malaria parasitaemia among the infants.

CONCLUSION

one-in-five ill young infants had malaria parasitaemia with heavy parasitaemia in 23.8% of infected infants. Malaria parasitaemia was associated with modifiable factors, high index of suspicion in endemic region and optimal maternal and child care services may assist to reduce the burden of malaria in this age group.

The Role of Nutrition in COVID-19 Susceptibility and Severity of Disease: A Systematic Review

BACKGROUND

Many nutrients have powerful immunomodulatory actions with the potential to alter susceptibility to coronavirus disease 2019 (COVID-19) infection, progression to symptoms, likelihood of severe disease, and survival.

OBJECTIVE

The aim was to review the latest evidence on how malnutrition across all its forms (under- and overnutrition and micronutrient status) may influence both susceptibility to, and progression of, COVID-19.

METHODS

We synthesized information on 13 nutrition-related components and their potential interactions with COVID-19: overweight, obesity, and diabetes; protein-energy malnutrition; anemia; vitamins A, C, D, and E; PUFAs; iron; selenium; zinc; antioxidants; and nutritional support. For each section we provide: 1) a landscape review of pertinent material; 2) a systematic search of the literature in PubMed and EMBASE databases, including a wide range of preprint servers; and 3) a screen of 6 clinical trial registries. All original research was considered, without restriction to study design, and included if it covered: 1) severe acute respiratory syndrome coronavirus (CoV) 2 (SARS-CoV-2), Middle East respiratory syndrome CoV (MERS-CoV), or SARS-CoV viruses and 2) disease susceptibility or 3) disease progression, and 4) the nutritional component of interest. Searches took place between 16 May and 11 August 2020.

RESULTS

Across the 13 searches, 2732 articles from PubMed and EMBASE, 4164 articles from the preprint servers, and 433 trials were returned. In the final narrative synthesis, we include 22 published articles, 38 preprint articles, and 79 trials.

CONCLUSIONS

Currently there is limited evidence that high-dose supplements of micronutrients will either prevent severe disease or speed up recovery. However, results of clinical trials are eagerly awaited. Given the known impacts of all forms of malnutrition on the immune system, public health strategies to reduce micronutrient deficiencies and undernutrition remain of critical importance. Furthermore, there is strong evidence that prevention of obesity and type 2 diabetes will reduce the risk of serious COVID-19 outcomes. This review is registered at PROSPERO as CRD42020186194.

JTZ-951 (enarodustat), a hypoxia-inducible factor prolyl hydroxylase inhibitor, improves iron utilization and anemia of inflammation: Comparative study against recombinant erythropoietin in rat

Anemia with inflammation-induced defective iron utilization is a pathological condition observed in patients suffering from chronic kidney disease (CKD) or chronic inflammatory disease. There is no reasonable treatment for these conditions, because the effects of erythropoiesis stimulating agents (ESAs) or iron supplementation in the treatment of anemia are insufficient. JTZ-951 (enarodustat) has been characterized as a novel, orally bioavailable inhibitor of hypoxia-inducible factor prolyl hydroxylase (HIF-PH), and has been developed as a novel therapeutic agent for anemia with CKD. In this study, the effects of JTZ-951 on iron utilization during erythropoiesis and on anemia of inflammation were compared with those of recombinant human erythropoietin (rHuEPO) using normal rat and rat model of anemia of inflammation. In normal rats, under conditions in which JTZ-951 and rHuEPO showed similar erythropoietic effect, repeated doses of JTZ-951 induced erythropoiesis while retaining the hemoglobin content in red blood cells, while administration of rHuEPO resulted in decrease in some erythrocyte-related parameters. As for iron-related parameters during erythropoiesis, JTZ-951 exhibited more efficient iron utilization compared to rHuEPO. A single dose of JTZ-951 resulted in decrease in hepcidin expression observed within 24 h after administration, but a single dose of rHuEPO did not. In a rat model of anemia of inflammation (also known as a model with functional iron-deficiency), JTZ-951 showed erythropoietic effect, in contrast with rHuEPO. These results suggest that, unlike rHuEPO, JTZ-951 stimulates erythropoiesis by increasing iron utilization, and improves anemia of inflammation.

On Iron Metabolism and Its Regulation

Iron is a critical metal for several vital biological processes. Most of the body’s iron is bound to hemoglobin in erythrocytes. Iron from senescent red blood cells is recycled by macrophages in the spleen, liver and bone marrow. Dietary iron is taken up by the divalent metal transporter 1 (DMT1) in enterocytes and transported to portal blood via ferroportin (FPN), where it is bound to transferrin and taken up by hepatocytes, macrophages and bone marrow cells via transferrin receptor 1 (TfR1). While most of the physiologically active iron is bound hemoglobin, the major storage of most iron occurs in the liver in a ferritin-bound fashion. In response to an increased iron load, hepatocytes secrete the peptide hormone hepcidin, which binds to and induces internalization and degradation of the iron transporter FPN, thus controlling the amount of iron released from the cells into the blood. This review summarizes the key mechanisms and players involved in cellular and systemic iron regulation.

Malaria is a cause of iron deficiency in African children

Malaria and iron deficiency (ID) are common and interrelated public health problems in African children. Observational data suggest that interrupting malaria transmission reduces the prevalence of ID1. To test the hypothesis that malaria might cause ID, we used sickle cell trait (HbAS, rs334 ), a genetic variant that confers specific protection against malaria2, as an instrumental variable in Mendelian randomization analyses. HbAS was associated with a 30% reduction in ID among children living in malaria-endemic countries in Africa (n = 7,453), but not among individuals living in malaria-free areas (n = 3,818). Genetically predicted malaria risk was associated with an odds ratio of 2.65 for ID per unit increase in the log incidence rate of malaria. This suggests that an intervention that halves the risk of malaria episodes would reduce the prevalence of ID in African children by 49%.

Disrupted Iron Metabolism and Mortality during Co-infection with Malaria and an Intestinal Gram-Negative Extracellular Pathogen

Individuals with malaria exhibit increased morbidity and mortality when infected with Gram-negative (Gr−) bacteria. To explore this experimentally, we performed co-infection of mice with Plasmodium chabaudi and Citrobacter rodentium, an extracellular Gr− bacterial pathogen that infects the large intestine. While single infections are controlled effectively, co-infection results in enhanced virulence that is characterized by prolonged systemic bacterial persistence and high mortality. Mortality in co-infected mice is associated with disrupted iron metabolism, elevated levels of plasma heme, and increased mitochondrial reactive oxygen species (ROS) production by phagocytes. In addition, iron acquisition by the bacterium plays a key role in pathogenesis because co-infection with a mutant C. rodentium strain lacking a critical iron acquisition pathway does not cause mortality. These results indicate that disrupted iron metabolism may drive mortality during co-infection with C. rodentium and P. chabaudi by both altering host immune responses and facilitating bacterial persistence.

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Co-infection with malaria and a Gram-negative bacterial pathogen leads to high mortality

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Co-infection leads to elevated plasma heme and systemic bacterial persistence

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Iron acquisition is critical for bacterial persistence and mortality

Prevention of iron deficiency anemia in infants and toddlers

Anemia, defined as a low blood hemoglobin concentration, is a major global public health problem. Identification of anemia is crucial to public health interventions. It is estimated globally that 273 million children under 5 years of age were anemic in 2011, and about ~50% of those cases were attributable to iron deficiency (Lancet Global Health 1:e16-e25, 2013). Iron-deficiency anemia (IDA) in infants adversely impacts short-term hematological indices and long-term neuro-cognitive functions of learning and memory that result in both fatigue and low economic productivity. IDA contributes to death and disability and is an important risk factor for maternal and perinatal mortality, including the risks for stillbirths, prematurity, and low birth weight (Comparative Quantification of Health Risks: Global and Regional Burden of Disease Attributable to Selected Major Risk Factors. Ch. 3 (World Health Organization, Geneva, 2004)). Reduction in early infantile anemia and newborn mortality rates is possible with easily implemented, low- to no-cost intervention such as delayed cord clamping (DCC). DCC until 1-3 min after birth facilitates placental transfusion and iron-rich blood flow to the newborn. DCC, an effective anemia prevention strategy, requires cooperation among health providers involved in childbirth, and a participatory culture change in public health. Public intervention strategies must consider multiple factors associated with anemia listed in this review before designing intervention studies that aim to reduce anemia prevalence in infants and toddlers. IMPACT: Anemia, defined as a low blood hemoglobin concentration, is a major global public health problem and identification of anemia is crucial to public health interventions. Delayed cord clamping (DCC) until 1-3 min after birth facilitates placental transfusion and iron-rich blood flow to the newborn. Reduction in early infantile anemia and newborn mortality rates is possible with easily implemented, low- to no-cost intervention such as DCC.

Iron in immune cell function and host defense

The control over iron availability is crucial under homeostatic conditions and even more in the case of an infection. This results from diverse properties of iron: first, iron is an important trace element for the host as well as for the pathogen for various cellular and metabolic processes, second, free iron catalyzes Fenton reaction and is therefore producing reactive oxygen species as a part of the host defense machinery, third, iron exhibits important effects on immune cell function and differentiation and fourth almost every immune activation in turn impacts on iron metabolism and spatio-temporal iron distribution. The central importance of iron in the host and microbe interplay and thus for the course of infections led to diverse strategies to restrict iron for invading pathogens. In this review, we focus on how iron restriction to the pathogen is a powerful innate immune defense mechanism of the host called "nutritional immunity". Important proteins in the iron-host-pathogen interplay will be discussed as well as the influence of iron on the efficacy of innate and adaptive immunity. Recently described processes like ferritinophagy and ferroptosis are further covered in respect to their impact on inflammation and infection control and how they impact on our understanding of the interaction of host and pathogen.

Risk of malaria in young children after periconceptional iron supplementation

This study in Burkina Faso investigated whether offspring of young mothers who had received weekly periconceptional iron supplementation in a randomised controlled trial were at increased risk of malaria. A child safety survey was undertaken in the peak month of malaria transmission towards the end of the trial to assess child iron biomarkers, nutritional status, anaemia and malaria outcomes. Antenatal iron biomarkers, preterm birth, fetal growth restriction and placental pathology for malaria and chorioamnionitis were assessed. Data were available for 180 babies surviving to the time of the survey when their median age was 9 months. Prevalence of maternal iron deficiency in the last trimester based on low body iron stores was 16%. Prevalence of active placental malaria infection was 24.8%, past infection 59% and chorioamnionitis 55.6%. Babies of iron supplemented women had lower median gestational age. Four out of five children ≥ 6 months were iron deficient, and 98% were anaemic. At 4 months malaria prevalence was 45%. Child iron biomarkers, anaemia and malaria outcomes did not differ by trial arm. Factors associated with childhood parasitaemia were third trimester C-reactive protein level (OR 2.1; 95% CI 1.1-3.9), active placental malaria (OR 5.8; 1.0-32.5, P = 0.042) and child body iron stores (OR 1.13; 1.04-1.23, P = 0.002). Chorioamnionitis was associated with reduced risk of child parasitaemia (OR 0.4; 0.1-1.0, P = 0.038). Periconceptional iron supplementation of young women did not alter body iron stores of their children. Higher child body iron stores and placental malaria increased risk of childhood parasitaemia.

Impact of bacterial infections on erythropoiesis

INTRODUCTION

The importance of iron is highlighted by the many complex metabolic pathways in which it is involved. A sufficient supply is essential for the effective production of 200 billion erythrocytes daily, a process called erythropoiesis.

AREAS COVERED

During infection, the human body can withhold iron from pathogens, mechanism termed nutritional immunity. The subsequent disturbances in iron homeostasis not only impact on immune function and infection control, but also negatively affect erythropoiesis. The complex interplay between iron, immunity, erythropoiesis and infection control on the molecular and clinical level are highlighted in this review. Diagnostic algorithms for correct interpretation and diagnosis of the iron status in the setting of infection are presented. Therapeutic concepts are discussed regarding effects on anemia correction, but also toward their role on the course of infection.

EXPERT OPINION

In the setting of infection, anemia is often neglected and its impact on the course of diseases is incompletely understood. Clinical expertise can be improved in correct diagnosing of anemia and disturbances of iron homeostasis. Systemic studies are needed to evaluate the impact of specific therapeutic interventions on anemia correction on the course of infection, but also on patients' cardiovascular performance and quality of life.

Immune responses to malaria pre-erythrocytic stages: Implications for vaccine development

Radiation-attenuated sporozoites induce sterilizing immunity and remain the 'gold standard' for malaria vaccine development. Despite practical challenges in translating these whole sporozoite vaccines to large-scale intervention programmes, they have provided an excellent platform to dissect the immune responses to malaria pre-erythrocytic (PE) stages, comprising both sporozoites and exoerythrocytic forms. Investigations in rodent models have provided insights that led to the clinical translation of various vaccine candidates-including RTS,S/AS01, the most advanced candidate currently in a trial implementation programme in three African countries. With advances in immunology, transcriptomics and proteomics, and application of lessons from past failures, an effective, long-lasting and wide-scale malaria PE vaccine remains feasible. This review underscores the progress in PE vaccine development, focusing on our understanding of host-parasite immunological crosstalk in the tissue environments of the skin and the liver. We highlight possible gaps in the current knowledge of PE immunity that can impact future malaria vaccine development efforts.

Implementation of a red blood cell-optical (RBO) channel for detection of latent iron deficiency anaemia by automated measurement of autofluorescence-emitting red blood cells

Iron deficiency is the most common and widespread nutritional disorder worldwide. The automated haematology analyser XN-30 (Sysmex, Kobe, Japan) was developed to detect malaria-infected red blood cells (RBCs) in human blood samples using flow cytometry. The optical system of the analyser detects autofluorescence (AF)-emitting RBCs containing iron-deficient haem groups and would aid in the diagnosis of anaemia resulting from iron deficiency. Here, an RBC-optical (RBO) channel was devised and implemented on the analyser. In vitro analyses showed that the analyser detected AF-emitting RBCs treated with 5-aminolevulinic acid. Furthermore, the analyser detected AF-emitting RBCs in mice fed a low iron diet and infected with a rodent malaria parasite; it could also be effectively used in humans. This study demonstrates that the analyser can quantitatively and reproducibly detect AF-emitting RBCs and measure other haematological parameters, suggesting its usefulness for the initial evaluation of latent iron deficiency anaemia in conjunction with the diagnosis of malaria.

Iron deficiency after kidney transplantation

Iron deficiency (ID) is highly prevalent in kidney transplant recipients (KTRs) and has been independently associated with an excess mortality risk in this population. Several causes lead to ID in KTRs, including inflammation, medication and an increased iron need after transplantation. Although many studies in other populations indicate a pivotal role for iron as a regulator of the immune system, little is known about the impact of ID on the immune system in KTRs. Moreover, clinical trials in patients with chronic kidney disease or heart failure have shown that correction of ID, with or without anaemia, improves exercise capacity and quality of life, and may improve survival. ID could therefore be a modifiable risk factor to improve graft and patient outcomes in KTRs; prospective studies are warranted to substantiate this hypothesis.

Hepcidin, an overview of biochemical and clinical properties

Hepcidin is a peptide hormone which helps in regulating iron homeostasis in the human body. Iron obtained from daily diet is passed through the intestinal enterocyte apical membrane via divalent metal transporter 1 (DMT1), which is either stored as ferritin or moved into the plasma by hepcidin-ferroportin (Fpn) as an exporter. Hepcidin (hepatic bactericidal protein) is a cysteine rich peptide, was initially identified as a urinary antimicrobial peptide. It contains 25 amino acids and four disulfide bridges. It has significant role in regulation of iron in the body. Stimulation of iron in plasma and further its storage is linked with the production of hepcidin. This enhancement of iron hampers the absorption of iron from the diet. The cause of hereditary recessive anemia also known as Iron-refractory iron deficiency anemia (IRIDA) is characterized by increased hepcidin production due to a gene mutation in the suppressor matriptase-2/TMPRSS6. During infection, hepcidin plays a defensive role against various infections by depleting the extracellular iron from the body. Moreover, hepcidin lowers the concentrations of iron from the duodenal enterocytes, macrophages and also decrease its transport across the placenta.This review highlights the significant role of hepcidin in the iron homeostasis and as an antimicrobial agent.

Review of Atypical Organometallic Compounds as Antimalarial Drugs

Organometallic compounds are molecules that contain at least one metal-carbon bond. Due to resistance of the Plasmodium parasite to traditional organic antimalarials, the use of organometallic compounds has become widely adopted in antimalarial drug discovery. Ferroquine, which was developed due to the emergence of chloroquine resistance, is currently the most advanced organometallic antimalarial drug and has paved the way for the development of new organometallic antimalarials. In this review, a general overview of organometallic antimalarial compounds and their antimalarial activity in comparison to purely organic antimalarials are presented. Furthermore, recent developments in the field are discussed, and future applications of this emerging class of therapeutics in antimalarial drug discovery are suggested.

Delayed iron improves iron status without altering malaria risk in severe malarial anemia

BACKGROUND

WHO guidelines recommend concurrent iron and antimalarial treatment in children with malaria and iron deficiency, but iron may not be well absorbed or utilized during a malaria episode.

OBJECTIVES

We aimed to determine whether starting iron 28 d after antimalarial treatment in children with severe malaria and iron deficiency would improve iron status and lower malaria risk.

METHODS

We conducted a randomized clinical trial on the effect of immediate compared with delayed iron treatment in Ugandan children 18 mo-5 y of age with 2 forms of severe malaria: cerebral malaria (CM; n = 79) or severe malarial anemia (SMA; n = 77). Asymptomatic community children (CC; n = 83) were enrolled as a comparison group. Children with iron deficiency, defined as zinc protoporphyrin (ZPP) ≥ 80 µmol/mol heme, were randomly assigned to receive a 3-mo course of daily oral ferrous sulfate (2 mg · kg-1 · d-1) either concurrently with antimalarial treatment (immediate arm) or 28 d after receiving antimalarial treatment (delayed arm). Children were followed for 12 mo.

RESULTS

All children with CM or SMA, and 35 (42.2%) CC, were iron-deficient and were randomly assigned to immediate or delayed iron treatment. Immediate compared with delayed iron had no effect in any of the 3 study groups on the primary study outcomes (hemoglobin concentration and prevalence of ZPP ≥ 80 µmol/mol heme at 6 mo, malaria incidence over 12 mo). However, after 12 mo, children with SMA in the delayed compared with the immediate arm had a lower prevalence of iron deficiency defined by ZPP (29.4% compared with 65.6%, P = 0.006), a lower mean concentration of soluble transferrin receptor (6.1 compared with 7.8 mg/L, P = 0.03), and showed a trend toward fewer episodes of severe malaria (incidence rate ratio: 0.39; 95% CI: 0.14, 1.12).

CONCLUSIONS

In children with SMA, delayed iron treatment did not increase hemoglobin concentration, but did improve long-term iron status over 12 mo without affecting malaria incidence.This trial was registered at clinicaltrials.gov as NCT01093989.

Hemoglobin and hepcidin have good validity and utility for diagnosing iron deficiency anemia among pregnant women

BACKGROUND/OBJECTIVES

Screening and diagnosis of iron deficiency anemia (IDA) is cumbersome as it may require testing for hemoglobin, ferritin, and an inflammatory biomarker. The aim of this study was to compare the diagnostic capacity of hematologic biomarkers to detect IDA among pregnant women in Tanzania.

SUBJECTS/METHODS

We pooled data from an iron supplementation trial of 1500 iron-replete pregnant woman and a prospective cohort of 600 iron-deficient pregnant women. Receiver operating characteristic curves (ROC) for hematologic biomarkers were used to assess the sensitivity, specificity, and area under the curve (AUC) for iron deficiency (ID) and iron deficiency anemia (IDA), crude, or corrected for inflammation. Regression models assessed the relationship of baseline biomarker categories (gestational age <27 weeks) and IDA at delivery.

RESULTS

Hemoglobin had the largest AUC for crude ID (0.96), while hepcidin had the largest AUC for corrected ID (0.80). The optimal hepcidin cutoff for the diagnosis of corrected IDA based on maximal sensitivity and specificity was ≤1.6 µg/L. An hepcidin cutoff of <4.3 µg/L had a sensitivity of 95% for regression-corrected ID. Among iron-replete women who did not receive iron, the association of baseline hemoglobin >110 g/L with IDA at delivery (RR = 0.73; 95% CI: 0.47, 1.13) was attenuated. Baseline hepcidin >1.6 µg/L was associated with reduced risk of anemia at delivery by 49% (95% CI: 27%, 45%).

CONCLUSIONS

Ascertaining hemoglobin and hepcidin levels may improve the targeting of iron supplementation programs in resource-limited countries, though hepcidin's high costs may limit its use.

Ferritin: An Inflammatory Player Keeping Iron at the Core of Pathogen-Host Interactions

Iron is an essential element for virtually all cell types due to its role in energy metabolism, nucleic acid synthesis and cell proliferation. Nevertheless, if free, iron induces cellular and organ damage through the formation of free radicals. Thus, iron levels must be firmly controlled. During infection, both host and microbe need to access iron and avoid its toxicity. Alterations in serum and cellular iron have been reported as important markers of pathology. In this regard, ferritin, first discovered as an iron storage protein, has emerged as a biomarker not only in iron-related disorders but also in inflammatory diseases, or diseases in which inflammation has a central role such as cancer, neurodegeneration or infection. The basic research on ferritin identification and functions, as well as its role in diseases with an inflammatory component and its potential as a target in host-directed therapies, are the main considerations of this review.

Effects of lemon decoction on malaria parasite clearance and selected hematological parameters in Plasmodium berghei ANKA infected mice

BACKGROUND

Citrus plants particularly lemon (Citrus limon L.) concoctions are ethno-medically used for treatment of infectious diseases including malaria. Therefore, we set an experiment to investigate the effects of lemon decoction in mice infected with Plasmodium berghei ANKA parasites.

METHODS

Antimalarial activity was determined using Rane's curative test on 25 Theiler's albino mice. Twenty mice were each injected with 2 × 107 infected red blood cells (iRBCs). The mice were divided into four groups, consisting of five mice per group. Each group received an oral dose of either 5% carboxymethyl cellulose/placebo (negative infected control), lemon decoction (Citrus limon [CILI extract]) alone or a combination of artemether/lumefantrine (A/LU, 28 mg/kg) and CILI extract and A/LU alone. A fifth group of mice consisted of uninfected mice as parasite-negative control.

RESULTS

Within 72 hours after initiation of treatment, the mean percentage parasitemia ± standard deviation of the CILI extract group (24.2% ± 9.83%) was lower compared to placebo group (40.0% ± 14.78%), p = 0.037. CILI extract group was found to have an increased survival rate (11 days ± 1.6 days) as compared to placebo group (8.6 days ± 3.4 days), p = 0.226. Mice in the combination group (A/LU + CILI extract) had the highest mean counts in terms of hemato-immunological parameters, whereas those in the CILI extract alone had the lowest hematocrit levels. The study also found that mice that received a combination of CILI extract and A/LU exhibited a decreased lag time with regards to time required to clear 99% of parasites (58.8 h vs. 64.2 h, p = 0.681) as compared to the A/LU alone group.

CONCLUSION

Lemon decoction demonstrated antimalarial activity in mice infected with P. berghei ANKA through parasites suppression by 39% as compared to those received placebo. However, when used alone, lemons did not suffice as a cure but in combination with standard antimalarials, lemons promoted early parasite clearance with an improved hematological parameters.

The Role of Iron Regulation in Immunometabolism and Immune-Related Disease

Immunometabolism explores how the intracellular metabolic pathways in immune cells can regulate their function under different micro-environmental and (patho-)-physiological conditions (Pearce, 2010; Buck et al., 2015; O'Neill and Pearce, 2016). In the last decade great advances have been made in studying and manipulating metabolic programs in immune cells. Immunometabolism has primarily focused on glycolysis, the TCA cycle and oxidative phosphorylation (OXPHOS) as well as free fatty acid synthesis and oxidation. These pathways are important for providing the energy needs of cell growth, membrane rigidity, cytokine production and proliferation. In this review, we will however, highlight the specific role of iron metabolism at the cellular and organismal level, as well as how the bioavailability of this metal orchestrates complex metabolic programs in immune cell homeostasis and inflammation. We will also discuss how dysregulation of iron metabolism contributes to alterations in the immune system and how these novel insights into iron regulation can be targeted to metabolically manipulate immune cell function under pathophysiological conditions, providing new therapeutic opportunities for autoimmunity and cancer.