👤 Arne Yndestad

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. 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. (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. 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. Show less

The immune response during falciparum malaria mediates both harmful and protective effects on the host; however the participating molecules have not been fully defined. Interleukin (IL)-27 is a pleiotropic cytokine exerting both inflammatory and anti-inflammatory effects, but data on IL-27 in malaria patients are scarce. Clinical data and blood samples were collected from adults in Mozambique with P. falciparum infection, with (n = 70) and without (n = 61) HIV-1 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 and PBMC using hemozoin crystals. Samples were analyzed using enzyme immunoassays and quantitative PCR. (i) IL-27 was markedly up-regulated in malaria patients compared with controls and HIV-infected patients without malaria, showing no relation to HIV co-infection. (ii) IL-27 was correlated with P. falciparum parasitemia and von Willebrand factor as a marker of endothelial activation, but not with disease severity. (iii) In vitro, IL-27 modulated the hemozoin-mediated cytokine response in endothelial cells and PBMC with enhancing effects on IL-6 and attenuating effects on IL-8. Our findings show that IL-27 is regulated during falciparum malaria, mediating both inflammatory and anti-inflammatory effects, potentially playing an immune-regulatory role during falciparum malaria. Show less

Interleukin (IL)-10 is a prototypical anti-inflammatory cytokine that has been shown to attenuate atherosclerosis development. In addition to its anti-inflammatory properties, the anti-atherogenic effect of IL-10 has recently also been suggested to reflect a complex effect of IL-10 on lipid metabolism in macrophages. In the present study we examined the effects of IL-10 on cholesterol efflux mechanism in lipid-loaded THP-1 macrophages. Our main findings were: (i) IL-10 significantly enhanced cholesterol efflux induced by fetal-calf serum, high-density lipoprotein (HDL)2 and apolipoprotein A-1. (ii) The IL-10-mediated effects on cholesterol efflux were accompanied by an increased IL-10-mediated expression of the ATP-binding cassette transporters ABCA1 and ABCG1, that was further enhanced when the cells were co-activated with the liver X receptor (LXR)α agonist (22R)-hydroxycholesterol. (iii) The effect of LXRα activation on the IL-10-mediated effects on the ATP-binding cassette transporters seems to include enhancing effects on the IL-10 receptor 1 (IL10R1) expression and interaction with STAT-3 signaling. (iv) These enhancing effects on ABCA1 and ABCG1 was not seen when the cells were stimulated with the IL-10 family members IL-22 and IL-24. This study suggests that the anti-atherogenic properties of IL-10 may include enhancing effects on cholesterol efflux mechanism that involves cross-talk with LXRα activation. Show less