Pro- and anti-inflammatory cytokines in children with malaria in Franceville, Gabon.

Severe Plasmodium falciparum malaria anemia (SMA) is a major cause of mortality in pediatric wards. Variations in inflammatory mediator production play an essential role in disease outcomes. Indeed, several studies have shown the involvement of pro- and anti-inflammatory cytokines such as IFN-γ, IL-6, TNF-α and IL-10 in malaria immunopathology. In other hand the exact role of Th17 cytokines such as IL-17, IL-22 and IL-21 in malaria remains poorly documented. Here, we investigated IFN-γ, TNF-α, IL-6, IL-12, IL-10, IL-4, IL-13, IL-17, IL-22 and IL-21 circulating levels and their association with malaria anemia and parasitemia in Gabonese children. Levels of IFN-γ (500 ± 100.2 pg/ml), IL-6 (64 ± 14.2 pg/ml), IL-10 (505 ± 35 pg/ml), IL-13 (30.6 ± 5.6 pg/ml) were significantly higher (P < 0.03) in infected children than in uninfected controls (210 ± 20 pg/ml, 17.5 pg/ml, 50 ± 25.9, pg/ml, 17.48 pg/ml, respectively). IFN-γ levels were significantly lower (P = 0.04) in children with SMA (400 ± 200 pg/ml) than in those with uncomplicated malaria (900 ± 450 pg/ml) and higher in those with parasitemia (P = 0.019). Levels of IL-6 and IL-10 were significantly higher in children with malarial anemia (P < 0.001) and hyperparasitemia (P < 0.0001). A significant association between IL-10 levels and parasite density was observed (P < 0.00001). IL-22 levels were significantly higher (P = 0.01) in infected children (72.57 ± 7.5 pg/ml) than in the controls (54.96 ± 1.93 pg/ml). IL-21 levels (44.46 ± 17.27 pg/ml) decreased with the severity of anemia (P < 0.05), whereas IL-17 levels increased in children with SMA (12.25 ± 1.25 pg/ml) than in those with mild malaria anemia (MMA: 6.2 ± 5.25 pg/ml, P = 0.002). Data suggest possible role of IFN-γ in the protection against SMA and parasite clearance. However, IL-6 and IL-10 could play a role in inflammatory response and pathophysiology of severe malaria anemia. Also, the role of IL-22 and IL-17 in P. falciparum malaria infection should be investigated.