Cerebrospinal fluid and serum biomarkers of cerebral malaria mortality in Ghanaian children

Abstract

Background: Plasmodium falciparum can cause a diffuse encephalopathy known as cerebral malaria (CM), a major contributor to malaria associated mortality. Despite treatment, mortality due to CM can be as high as 30% while 10% of survivors of the disease may experience short- and long-term neurological complications. The pathogenesis of CM and other forms of severe malaria is multi-factorial and appear to involve cytokine and chemokine homeostasis, inflammation and vascular injury/repair. Identification of prognostic markers that can predict CM severity will enable development of better intervention.

Methods: Postmortem serum and cerebrospinal fluid (CSF) samples were obtained within 2-4 hours of death in Ghanaian children dying of CM, severe malarial anemia (SMA), and non-malarial (NM) causes. Serum and CSF levels of 36 different biomarkers (IL-1beta, IL-1ra, IL-2, IL-4, IL-5, IL-6, IL-7, IL-8, IL-9, IL-10, IL-12 (p70), IL-13, IL-15, IL-17, Eotaxin, FGF basic protein, CRP, G-CSF, GM-CSF, IFN-gamma, TNF-alpha, IP-10, MCP-1 (MCAF), MIP-1alpha, MIP-1beta, RANTES, SDF-1alpha, CXCL11 (I-TAC), Fas-ligand [Fas-L], soluble Fas [sFas], sTNF-R1 (p55), sTNF-R2 (p75), MMP-9, TGF-beta1, PDGF bb and VEGF) were measured and the results compared between the 3 groups.

Results: After Bonferroni adjustment for other biomarkers, IP-10 was the only serum biomarker independently associated with CM mortality when compared to SMA and NM deaths. Eight CSF biomarkers (IL-1ra, IL-8, IP-10, PDGFbb, MIP-1beta, Fas-L, sTNF-R1, and sTNF-R2) were significantly elevated in CM mortality group when compared to SMA and NM deaths. Additionally, CSF IP-10/PDGFbb median ratio was statistically significantly higher in the CM group compared to SMA and NM groups.

Conclusion: The parasite-induced local cerebral dysregulation in the production of IP-10, 1L-8, MIP-1beta, PDGFbb, IL-1ra, Fas-L, sTNF-R1, and sTNF-R2 may be involved in CM neuropathology, and their immunoassay may have potential utility in predicting mortality in CM.

Figure 1

Postmortem serum biomarker levels of IL-1β, IL-1ra, IL-6, IL-8, TNF-α, and IFN-γ in children dying with CM, SMA, NM causes. CM, cerebral malaria; SMA, severe malarial anemia; NM, non-malaria. Box plots representing medians with 25^th and 75^th percentiles, bars for 10^th and 90^th percentiles, and points for outliers of biomarker concentrations. Only statistically significant P values after Bonferroni adjustment for the other biomarkers are shown.

Figure 2

Postmortem serum biomarker levels of IL-10, TGF-βx, sTNF-R1, sTNF-R2, sFas, and Fas-L in children dying with CM, SMA, NM causes. CM, cerebral malaria; SMA, severe malarial anemia; NM, non-malaria. Box plots representing medians with 25^th and 75^th percentiles, bars for 10^th and 90^th percentiles, and points for outliers of biomarker concentrations. Only statistically significant P values after Bonferroni adjustment for the other biomarkers are shown.

Figure 3

Postmortem serum biomarker levels of IP-10, RANTES, MCP-1, MIP-1α, MIP-1β, and PDGFbb in children dying with CM, SMA, NM causes. CM, cerebral malaria; SMA, severe malarial anemia; NM, non-malaria. Box plots representing medians with 25^th and 75^th percentiles, bars for 10^th and 90^th percentiles, and points for outliers of biomarker concentrations. Only statistically significant P values after Bonferroni adjustment for the other biomarkers are shown.

Figure 4

Postmortem CSF biomarker levels of IL-1β, IL-1ra, IL-6, IL-8, TNF-α, and IFN-γ in children dying with CM, SMA, NM causes. CM, cerebral malaria; SMA, severe malarial anemia; NM, non-malaria. Box plots representing medians with 25^th and 75^th percentiles, bars for 10^th and 90^th percentiles, and points for outliers of biomarker concentrations. Only statistically significant P values after Bonferroni adjustment for the other biomarkers are shown.

Figure 5

Postmortem CSF biomarker levels of IL-10, TGF-βx, sTNF-R1, sTNF-R2, sFas, and Fas-L in children dying with CM, SMA, NM causes. CM, cerebral malaria; SMA, severe malarial anemia; NM, non-malaria. Box plots representing medians with 25^th and 75^th percentiles, bars for 10^th and 90^th percentiles, and points for outliers of biomarker concentrations. Only statistically significant P values after Bonferroni adjustment for the other biomarkers are shown.

Figure 6

Postmortem CSF biomarker levels of IP-10, RANTES, MCP-1, MIP-1α, MIP-1β, and PDGFbb in children dying with CM, SMA, NM causes. CM, cerebral malaria; SMA, severe malarial anemia; NM, non-malaria. Box plots representing medians with 25^th and 75^th percentiles, bars for 10^th and 90^th percentiles, and points for outliers of biomarker concentrations. Only statistically significant P values after Bonferroni adjustment for the other biomarkers are shown.