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Abuga KM, Nairz M, MacLennan CA, Atkinson SH. Severe anaemia, iron deficiency, and susceptibility to invasive bacterial infections. Wellcome Open Res 2023; 8:48. [PMID: 37600584 PMCID: PMC10439361 DOI: 10.12688/wellcomeopenres.18829.1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/18/2023] [Indexed: 08/22/2023] Open
Abstract
Severe anaemia and invasive bacterial infections remain important causes of hospitalization and death among young African children. The emergence and spread of antimicrobial resistance demand better understanding of bacteraemia risk factors to inform prevention strategies. Epidemiological studies have reported an association between severe anaemia and bacteraemia. In this review, we explore evidence that severe anaemia is associated with increased risk of invasive bacterial infections in young children. We describe mechanisms of iron dysregulation in severe anaemia that might contribute to increased risk and pathogenesis of invasive bacteria, recent advances in knowledge of how iron deficiency and severe anaemia impair immune responses to bacterial infections and vaccines, and the gaps in our understanding of mechanisms underlying severe anaemia, iron deficiency, and the risk of invasive bacterial infections.
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Affiliation(s)
- Kelvin M. Abuga
- Kenya Medical Research Institute (KEMRI) Centre for Geographical Medicine Research-Coast, KEMRI-Wellcome Trust Research Programme, Kilifi, 80108, Kenya
- Open University, KEMRI-Wellcome Trust Research Programme – Accredited Research Centre, Kilifi, 80108, Kenya
| | - Manfred Nairz
- Department of Internal Medicine II, Medical University of Innsbruck, Innsbruck, 6020, Austria
| | - Calman A. MacLennan
- Jenner Institute, Nuffield Department of Medicine, University of Oxford, Oxford, OX3 7DQ, UK
| | - Sarah H. Atkinson
- Kenya Medical Research Institute (KEMRI) Centre for Geographical Medicine Research-Coast, KEMRI-Wellcome Trust Research Programme, Kilifi, 80108, Kenya
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, OX3 7LG, UK
- Department of Paediatrics, University of Oxford, Oxford, OX3 9DU, UK
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Abuga KM, Muriuki JM, Uyoga SM, Mwai K, Makale J, Mogire RM, Macharia AW, Mohammed S, Muthumbi E, Mwarumba S, Mturi N, Bejon P, Scott JAG, Nairz M, Williams TN, Atkinson SH. Hepcidin regulation in Kenyan children with severe malaria and non-typhoidal Salmonella bacteremia. Haematologica 2021; 107:1589-1598. [PMID: 34498446 PMCID: PMC9244826 DOI: 10.3324/haematol.2021.279316] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2021] [Indexed: 11/09/2022] Open
Abstract
Malaria and invasive non-typhoidal Salmonella (NTS) are life-threatening infections that often co-exist in African children. The iron-regulatory hormone hepcidin is highly upregulated during malaria and controls the availability of iron, a critical nutrient for bacterial growth. We investigated the relationship between Plasmodium falciparum malaria and NTS bacteremia in all pediatric admissions aged <5 years between August 1998 and October 2019 (n=75,034). We then assayed hepcidin and measures of iron status in five groups: (1) children with concomitant severe malarial anemia (SMA) and NTS (SMA+NTS, n=16); and in matched children with (2) SMA (n=33); (3) NTS (n=33); (4) cerebral malaria (CM, n=34); and (5) community-based children. SMA and severe anemia without malaria were associated with a 2-fold or more increased risk of NTS bacteremia, while other malaria phenotypes were not associated with increased NTS risk. Children with SMA had lower hepcidin/ferritin ratios (0.10; interquartile range [IQR]: 0.03-0.19) than those with CM (0.24; IQR: 0.14-0.69; P=0.006) or asymptomatic malaria (0.19; IQR: 0.09-0.46; P=0.01) indicating suppressed hepcidin levels. Children with SMA+NTS had lower hepcidin levels (9.3 ng/mL; IQR: 4.7-49.8) and hepcidin/ferritin ratios (0.03; IQR: 0.01-0.22) than those with NTS alone (105.8 ng/mL; IQR: 17.3-233.3; P=0.02 and 0.31; IQR: 0.06-0.66; P=0.007, respectively). Since hepcidin degrades ferroportin on the Salmonella-containing vacuole, we hypothesize that reduced hepcidin in children with SMA might contribute to NTS growth by modulating iron availability for bacterial growth. Further studies are needed to understand how the hepcidin-ferroportin axis might mediate susceptibility to NTS in severely anemic children.
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Affiliation(s)
- Kelvin M. Abuga
- Kenya Medical Research Institute (KEMRI) Center for Geographic Medicine Research, KEMRI-Wellcome Trust Research Program, Kilifi, Kenya,Department of Public Health, School of Human and Health Sciences, Pwani University, Kilifi, Kenya,Kelvin M. Abuga
| | - John Muthii Muriuki
- Kenya Medical Research Institute (KEMRI) Center for Geographic Medicine Research, KEMRI-Wellcome Trust Research Program, Kilifi, Kenya
| | - Sophie M. Uyoga
- Kenya Medical Research Institute (KEMRI) Center for Geographic Medicine Research, KEMRI-Wellcome Trust Research Program, Kilifi, Kenya
| | - Kennedy Mwai
- Kenya Medical Research Institute (KEMRI) Center for Geographic Medicine Research, KEMRI-Wellcome Trust Research Program, Kilifi, Kenya,Epidemiology and Biostatistics Division, School of Public Health, University of the Witwatersrand, Johannesburg, South Africa
| | - Johnstone Makale
- Kenya Medical Research Institute (KEMRI) Center for Geographic Medicine Research, KEMRI-Wellcome Trust Research Program, Kilifi, Kenya
| | - Reagan M. Mogire
- Kenya Medical Research Institute (KEMRI) Center for Geographic Medicine Research, KEMRI-Wellcome Trust Research Program, Kilifi, Kenya,Open University, KEMRI-Wellcome Trust Research Program – Accredited Research Center, Kilifi, Kenya
| | - Alex W. Macharia
- Kenya Medical Research Institute (KEMRI) Center for Geographic Medicine Research, KEMRI-Wellcome Trust Research Program, Kilifi, Kenya,Open University, KEMRI-Wellcome Trust Research Program – Accredited Research Center, Kilifi, Kenya
| | - Shebe Mohammed
- Kenya Medical Research Institute (KEMRI) Center for Geographic Medicine Research, KEMRI-Wellcome Trust Research Program, Kilifi, Kenya
| | - Esther Muthumbi
- Kenya Medical Research Institute (KEMRI) Center for Geographic Medicine Research, KEMRI-Wellcome Trust Research Program, Kilifi, Kenya
| | - Salim Mwarumba
- Kenya Medical Research Institute (KEMRI) Center for Geographic Medicine Research, KEMRI-Wellcome Trust Research Program, Kilifi, Kenya
| | - Neema Mturi
- Kenya Medical Research Institute (KEMRI) Center for Geographic Medicine Research, KEMRI-Wellcome Trust Research Program, Kilifi, Kenya
| | - Philip Bejon
- Kenya Medical Research Institute (KEMRI) Center for Geographic Medicine Research, KEMRI-Wellcome Trust Research Program, Kilifi, Kenya,Center for Tropical Medicine and Global Health, Nuffield Department of Clinical Medicine, University of Oxford, Oxford, UK
| | - J. Anthony G. Scott
- Kenya Medical Research Institute (KEMRI) Center for Geographic Medicine Research, KEMRI-Wellcome Trust Research Program, Kilifi, Kenya,Department of Infectious Disease Epidemiology, London School of Hygiene and Tropical Medicine, London, UK
| | - Manfred Nairz
- Department of Internal Medicine II, Medical University Innsbruck, Innsbruck, Austria
| | - Thomas N. Williams
- Kenya Medical Research Institute (KEMRI) Center for Geographic Medicine Research, KEMRI-Wellcome Trust Research Program, Kilifi, Kenya,Center for Tropical Medicine and Global Health, Nuffield Department of Clinical Medicine, University of Oxford, Oxford, UK,Department of Infectious Diseases and Institute of Global Health Innovation, Imperial College, London, UK
| | - Sarah H. Atkinson
- Kenya Medical Research Institute (KEMRI) Center for Geographic Medicine Research, KEMRI-Wellcome Trust Research Program, Kilifi, Kenya,Center for Tropical Medicine and Global Health, Nuffield Department of Clinical Medicine, University of Oxford, Oxford, UK,Department of Pediatrics, University of Oxford, Oxford, UK,Sarah H. Atkinson
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Abuga KM, Rockett KA, Muriuki JM, Koch O, Nairz M, Sirugo G, Bejon P, Kwiatkowski DP, Prentice AM, Atkinson SH. Interferon-gamma polymorphisms and risk of iron deficiency and anaemia in Gambian children. Wellcome Open Res 2020; 5:40. [PMID: 32420456 PMCID: PMC7202087 DOI: 10.12688/wellcomeopenres.15750.2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/28/2020] [Indexed: 12/15/2022] Open
Abstract
Background: Anaemia is a major public health concern especially in African children living in malaria-endemic regions. Interferon-gamma (IFN-γ) is elevated during malaria infection and is thought to influence erythropoiesis and iron status. Genetic variants in the IFN-γ gene (IFNG) are associated with increased IFN-γ production. We investigated putative functional single nucleotide polymorphisms (SNPs) and haplotypes of IFNG in relation to nutritional iron status and anaemia in Gambian children over a malaria season. Methods: We used previously available data from Gambian family trios to determine informative SNPs and then used the Agena Bioscience MassArray platform to type five SNPs from the IFNG gene in a cohort of 780 Gambian children aged 2-6 years. We also measured haemoglobin and biomarkers of iron status and inflammation at the start and end of a malaria season. Results: We identified five IFNG haplotype-tagging SNPs ( IFNG-1616 [rs2069705], IFNG+874 [rs2430561], IFNG+2200 [rs1861493], IFNG+3234 [rs2069718] and IFNG+5612 [rs2069728]). The IFNG+2200C [rs1861493] allele was associated with reduced haemoglobin concentrations (adjusted β -0.44 [95% CI -0.75, -0.12]; Bonferroni adjusted P = 0.03) and a trend towards iron deficiency compared to wild-type at the end of the malaria season in multivariable models adjusted for potential confounders. A haplotype uniquely identified by IFNG+2200C was similarly associated with reduced haemoglobin levels and trends towards iron deficiency, anaemia and iron deficiency anaemia at the end of the malaria season in models adjusted for age, sex, village, inflammation and malaria parasitaemia. Conclusion: We found limited statistical evidence linking IFNG polymorphisms with a risk of developing iron deficiency and anaemia in Gambian children. More definitive studies are needed to investigate the effects of genetically influenced IFN-γ levels on the risk of iron deficiency and anaemia in children living in malaria-endemic areas.
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Affiliation(s)
- Kelvin M. Abuga
- Kenya Medical Research Institute (KEMRI) Centre for Geographic Medicine Coast, KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
| | - Kirk A. Rockett
- Wellcome Centre for Human Genetics, Nuffield Department of Medicine, University of Oxford, Oxford, UK
| | - John Muthii Muriuki
- Kenya Medical Research Institute (KEMRI) Centre for Geographic Medicine Coast, KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
- Open University, KEMRI-Wellcome Trust Research Programme – Accredited Research Centre, Kilifi, Kenya
| | - Oliver Koch
- Infection Medicine, The University of Edinburgh, Edinburgh, UK
| | - Manfred Nairz
- Department of Internal Medicine II, Medical University Innsbruck, Innsbruck, Austria
| | - Giorgio Sirugo
- Perelman School of Medicine, University of Pennsylvania, Philadelphia, USA
| | - Philip Bejon
- Kenya Medical Research Institute (KEMRI) Centre for Geographic Medicine Coast, KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, UK
| | - Dominic P. Kwiatkowski
- Wellcome Centre for Human Genetics, Nuffield Department of Medicine, University of Oxford, Oxford, UK
- Wellcome Sanger Institute, Hinxton, Cambridge, UK
- Big Data Institute, Li Ka Shing Centre for Health Information and Discovery, University of Oxford, Oxford, UK
| | - Andrew M. Prentice
- Medical Research Council Unit The Gambia at the London School of Hygiene and Tropical Medicine, Banjul, The Gambia
| | - Sarah H. Atkinson
- Kenya Medical Research Institute (KEMRI) Centre for Geographic Medicine Coast, KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, UK
- Department of Paediatrics, University of Oxford, Oxford, UK
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Abuga KM, Rockett KA, Muriuki JM, Koch O, Nairz M, Sirugo G, Bejon P, Kwiatkowski DP, Prentice AM, Atkinson SH. Interferon-gamma polymorphisms and risk of iron deficiency and anaemia in Gambian children. Wellcome Open Res 2020; 5:40. [PMID: 32420456 PMCID: PMC7202087 DOI: 10.12688/wellcomeopenres.15750.1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/25/2020] [Indexed: 11/08/2023] Open
Abstract
Background: Anaemia is a major public health concern especially in African children living in malaria-endemic regions. Interferon-gamma (IFN-γ) is elevated during malaria infection and is thought to influence erythropoiesis and iron status. Genetic variants in the IFN-γ gene (IFNG) are associated with increased IFN-γ production. We investigated putative functional single nucleotide polymorphisms (SNPs) and haplotypes of IFNG in relation to nutritional iron status and anaemia in Gambian children over a malaria season. Methods: We used previously available data from Gambian family trios to determine informative SNPs and then used the Agena Bioscience MassArray platform to type five SNPs from the IFNG gene in a cohort of 780 Gambian children. We also measured haemoglobin and biomarkers of iron status and inflammation at the start and end of a malaria season. Results: We identified five IFNG haplotype-tagging SNPs ( IFNG-1616 [rs2069705], IFNG+874 [rs2430561], IFNG+2200 [rs1861493], IFNG+3234 [rs2069718] and IFNG+5612 [rs2069728]). The IFNG+2200C [rs1861493] allele was associated with reduced haemoglobin concentrations (adjusted β -0.44 [95% CI -0.75, -0.12]; Bonferroni adjusted P = 0.03) and a trend towards iron deficiency compared to wild-type at the end of the malaria season in multivariable models adjusted for potential confounders. A haplotype uniquely identified by IFNG+2200C was similarly associated with reduced haemoglobin levels and trends towards iron deficiency, anaemia and iron deficiency anaemia at the end of the malaria season in models adjusted for age, sex, village, inflammation and malaria parasitaemia. Conclusion: We found limited statistical evidence linking IFNG polymorphisms with a risk of developing iron deficiency and anaemia in Gambian children. More definitive studies are needed to investigate the effects of genetically influenced IFN-γ levels on the risk of iron deficiency and anaemia in children living in malaria-endemic areas.
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Affiliation(s)
- Kelvin M. Abuga
- Kenya Medical Research Institute (KEMRI) Centre for Geographic Medicine Coast, KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
| | - Kirk A. Rockett
- Wellcome Centre for Human Genetics, Nuffield Department of Medicine, University of Oxford, Oxford, UK
| | - John Muthii Muriuki
- Kenya Medical Research Institute (KEMRI) Centre for Geographic Medicine Coast, KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
- Open University, KEMRI-Wellcome Trust Research Programme – Accredited Research Centre, Kilifi, Kenya
| | - Oliver Koch
- Infection Medicine, The University of Edinburgh, Edinburgh, UK
| | - Manfred Nairz
- Department of Internal Medicine II, Medical University Innsbruck, Innsbruck, Austria
| | - Giorgio Sirugo
- Perelman School of Medicine, University of Pennsylvania, Philadelphia, USA
| | - Philip Bejon
- Kenya Medical Research Institute (KEMRI) Centre for Geographic Medicine Coast, KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, UK
| | - Dominic P. Kwiatkowski
- Wellcome Centre for Human Genetics, Nuffield Department of Medicine, University of Oxford, Oxford, UK
- Wellcome Sanger Institute, Hinxton, Cambridge, UK
- Big Data Institute, Li Ka Shing Centre for Health Information and Discovery, University of Oxford, Oxford, UK
| | - Andrew M. Prentice
- Medical Research Council Unit The Gambia at the London School of Hygiene and Tropical Medicine, Banjul, The Gambia
| | - Sarah H. Atkinson
- Kenya Medical Research Institute (KEMRI) Centre for Geographic Medicine Coast, KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, UK
- Department of Paediatrics, University of Oxford, Oxford, UK
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