Depleted circulatory complement-lysis inhibitor (CLI) in childhood cerebral malaria returns to normal with convalescence

Abstract

Background: Cerebral malaria (CM), is a life-threatening childhood malaria syndrome with high mortality. CM is associated with impaired consciousness and neurological damage. It is not fully understood, as yet, why some children develop CM. Presented here is an observation from longitudinal studies on CM in a paediatric cohort of children from a large, densely-populated and malaria holoendemic, sub-Saharan, West African metropolis.

Methods: Plasma samples were collected from a cohort of children with CM, severe malarial anaemia (SMA), uncomplicated malaria (UM), non-malaria positive healthy community controls (CC), and coma and anemic patients without malaria, as disease controls (DC). Proteomic two-dimensional difference gel electrophoresis (2D-DIGE) and mass spectrometry were used in a discovery cohort to identify plasma proteins that might be discriminatory among these clinical groups. The circulatory levels of identified proteins of interest were quantified by ELISA in a prospective validation cohort.

Results: The proteome analysis revealed differential abundance of circulatory complement-lysis inhibitor (CLI), also known as Clusterin (CLU). CLI circulatory level was low at hospital admission in all children presenting with CM and recovered to normal level during convalescence (p < 0.0001). At acute onset, circulatory level of CLI in the CM group significantly discriminates CM from the UM, SMA, DC and CC groups.

Conclusions: The CLI circulatory level is low in all patients in the CM group at admission, but recovers through convalescence. The level of CLI at acute onset may be a specific discriminatory marker of CM. This work suggests that CLI may play a role in the pathophysiology of CM and may be useful in the diagnosis and follow-up of children presenting with CM.

Keywords: Biomarkers; Cerebral malaria; Childhood severe malaria; Pathogenesis.

Fig. 1

2D-gel electropherograms showing differentially abundant protein spots. Representative images of 2D-gel electropherograms from crude plasma samples (a) and immunodepleted plasma samples (b). Numbered circled spots represent protein spots showing a differential intensity between groups of over a 1.5-fold-change. Identities and intensity fold-change are depicted in Table 3. kDa molecular weight ladder in kDa, pI isoelectric point

Fig. 2

Plasma CLI concentration in clinical malaria syndromes both at acute onset and at recovery. a Plasma CLI protein level in clinical malaria syndromes at acute onset CM (0.04 ± 0.01); SMA (0.07 ± 0.04); UM (0.11 ± 0.05); DC (0.07 ± 0.03); CC (0.13 ± 0.08). b Two time-point graph showing levels of CLI at onset and recovery (paired samples) in the CM, SMA and UM groups, respectively. CLI complement-lysis inhibitor, CM = cerebral malaria, SMA severe malaria anaemia, UM uncomplicated malaria, DC disease controls, CC community controls; (mean ± standard deviation) g/L

Fig. 3

CLI discriminating potential between each malaria syndrome at acute onset or control group using ROC curve analysis. CLI complement-lysis inhibitor, CM cerebral malaria, SMA severe malaria anaemia, UM uncomplicated malaria, DC disease controls, CC community controls, AUC area under the curve