BMC Infectious Diseases (Oct 2021)

IL-18 and IL-18 binding protein are related to disease severity and parasitemia during falciparum malaria

  • Kari Otterdal,
  • Aase Berg,
  • Annika E. Michelsen,
  • Arne Yndestad,
  • Sam Patel,
  • Ida Gregersen,
  • Bente Halvorsen,
  • Thor Ueland,
  • Nina Langeland,
  • Pål Aukrust

DOI
https://doi.org/10.1186/s12879-021-06751-y
Journal volume & issue
Vol. 21, no. 1
pp. 1 – 10

Abstract

Read online

Abstract Background Several inflammatory molecules participate in the immune response to malaria. Interleukin (IL)-18 is an inflammatory cytokine activated by NLRP3 inflammasomes. In clinical falciparum malaria, with and without HIV co-infection, data on IL-18 and in particular on its binding protein, IL-18bp, is scarce. Methods Clinical data and blood samples were collected from adults in Mozambique with P. falciparum infection, with (n = 70) and without (n = 61) HIV co-infection, from HIV-infected patients with similar symptoms without malaria (n = 58) and from healthy controls (n = 52). In vitro studies were performed in endothelial cells using hemozoin crystals. Results (i) IL-18 and IL-18bp were markedly up-regulated during falciparum malaria with particular high levels in malaria patients co-infected with HIV and severe malaria disease. (ii) In the malaria group as a whole, both IL-18 and IL-18bp were positively correlated with disease severity, parasitemia, and endothelial cell activation as assessed by vWF in plasma. (iii) Whereas there was no change in IL-18 levels in malaria patients co-infected with HIV during follow-up, the patients with malaria only had slightly increased IL-18 levels. Further, the IL-18pb levels declined and thereby contributed to an increase in IL-18/IL-18bp ratio in all subgroups of malaria patients. (iv) IL-27, previously shown to be up-regulated in this malaria cohort, markedly induced a release of IL-18bp from endothelial cells in vitro, and notably, this presumably anti-inflammatory effect was counteracted by hemozoin. Conclusions Our findings suggest that the IL-18 system could be an important mediator in the immune pathogenesis during falciparum malaria, potentially also representing a target for therapy.

Keywords