CCR6 expression reduces mouse survival upon malarial challenge with Plasmodium berghei NK65 strain

BACKGROUND

It has been demonstrated that proteins expressed by liver-stage Plasmodium parasites can inhibit the translocation of transcription factors to the nucleus of different cells. This process would hinder the expression of immune genes, such as the CCL20 chemokine.

OBJECTIVE

Since CCR6 is the only cognate receptor for CCL20, we investigated the importance of this chemokine-receptor axis against rodent malaria.

METHODS

CCR6-deficient (KO) and wild-type (WT) C57BL/6 mice were challenged with Plasmodium berghei (Pb) NK65 sporozoites or infected red blood cells (iRBCs). Liver parasitic cDNA, parasitemia and serum cytokine concentrations were respectively evaluated through reverse transcription-polymerase chain reaction (RT-PCR), staining thin-blood smears with Giemsa solution, and enzyme-linked immunosorbent assay (ELISA).

FINDINGS

Although the sporozoite challenges yielded similar liver parasitic cDNA and parasitemia, KO mice presented a prolonged survival than WT mice. After iRBC challenges, KO mice kept displaying higher survival rates as well as a decreased IL-12 p70 concentration in the serum than WT mice.

CONCLUSION

Our data suggest that malaria triggered by PbNK65 liver- or blood-stage forms elicit a pro-inflammatory environment that culminates with a decreased survival of infected C57BL/6 mice.

Key words:
malaria; sporozoites; iRBCs; chemokine receptor; Th1 cytokines