Increased Gal-9 and Tim-3 expressions during liver damage in a murine malarial model

Malaria has been one of the most devastating tropical parasite infectious diseases popular around the world. Severe malaria is characterized by multiple organ dysfunctions, especially liver damage. However, the mechanisms of malarial liver injury remain to be better clarified. In this study, Kunming mice inoculated intraperitoneally (i.p.) with 10(6) Plasmodium berghei ANKA (PbANKA)-infected red blood cells (iRBCs) were investigated at days 5, 10, 15, and 20 post-infection (p.i.) to elucidate the profiles of T-cell immunoglobulin and mucin domain-3 (Tim-3) and its ligand galecin-9 (Gal-9) in the development of liver injury. The histopathology of livers and spleens from PbANKA-infected mice were observed, the parasite burdens of the livers and spleens using quantitative real-time PCR (qRT-PCR), Tim-3- and Gal-9-positive cells in the livers and spleens using immunohistochemical staining, and the mRNA levels of Tim-3, Gal-9, and cytokines in both the livers and spleens using qRT-PCR were examined. Our results showed that parasite burdens in the livers and spleens were significantly increased with time after PbANKA infection. Histological scores of both the liver and spleen tissues were significantly increased with time; the numbers of Tim-3- and Gal-9-positive cells were significantly increased in both the livers and spleens using immunohistochemical staining, and the mRNA levels of Tim-3 and Gal-9 in the livers and spleens were also significantly increased after infection. Our data suggests that the increase of Tim-3/Gal-9 expressions may play an important role in the liver damage during P. berghei infection.