Haemolysis and haem oxygenase-1 induction during persistent "asymptomatic" malaria infection in Burkinabé children.

Abstract

BACKGROUND:

The haemolysis associated with clinical episodes of malaria results in the liberation of haem, which activates the enzyme haem oxygenase-1 (HO-1). HO-1 has been shown to reduce neutrophil function and increase susceptibility to invasive bacterial disease. However, the majority of community-associated malaria infections are subclinical, often termed "asymptomatic" and the consequences of low-grade haemolysis during subclinical malaria infection are unknown.

STUDY DESIGN AND RESULTS:

As part of an ongoing study of subclinical malaria in Burkina Faso, 23 children with subclinical Plasmodium falciparum infections (determined by qPCR) were compared with 21 village-matched uninfected control children. Infected children showed evidence of persistent haemolysis over 35 days, with raised plasma haem and HO-1 concentrations. Concentrations of IL-10, which can also directly activate HO-1, were also higher in infected children compared to uninfected children. Regression analysis revealed that HO-1 was associated with haemolysis, but not with parasite density, anaemia or IL-10 concentration.

CONCLUSIONS:

This study reveals that subclinical P. falciparum malaria infection is associated with sustained haemolysis and the induction of HO-1. Given the association between HO-1, neutrophil dysfunction and increased risk of Salmonella bacteraemia, prolonged HO-1 induction may explain epidemiological associations and geographic overlap between malaria and invasive bacterial disease. Further studies are needed to understand the consequences of persistent subclinical malaria infection, low-grade haemolysis and raised HO-1 on immune cell function and risk of comorbidities.

• Authors: Jason P Mooney, Aissata Barry, Bronner P Gonçalves, Alfred B Tiono, Shehu S Awandu, Lynn Grignard, Chris J Drakeley, Christian Bottomley, Teun Bousema, Eleanor M Riley
• Journal: Malaria journal (Malar J) Vol. 17 Issue 1 Pg. 253 (Jul 06 2018) ISSN: 1475-2875 [Electronic] England
• PMID: 29980206 (Publication Type: Journal Article)

Chemical References

• Heme Oxygenase-1

Topics

• Asymptomatic Infections
• Burkina Faso
• Child
• Child, Preschool
• Female
• Heme Oxygenase-1 (genetics, metabolism)
• Hemolysis
• Humans
• Malaria, Falciparum (metabolism)
• Male
• Plasmodium falciparum (physiology)