Biology subjects

Yajuk, O.

Publications and source records attributed to Yajuk, O..

2 recordsLinked to original sources

bioRxiv2021

Neutrophils impose strong selective pressure against PfEMP1 variants implicated in cerebral malaria

Plasmodium falciparum, the deadliest form of human malaria, remains one of the major threats to human health in endemic regions. Its virulence is attributed to its ability to modify infected red blood cells (iRBC) to adhere to endothelial receptors by placing variable antigens known as PfEMP1 on the surface of the red cell. PfEMP1 expression on the red cell surface determines the cytoadhesive properties of the iRBCs and is implicated in severe manifestations of malaria. To evade antibody mediated responses the parasite undergoes continuous switches of expression between different PfEMP1 variants. Recently it became clear that in addition to antibody mediated responses, PfEMP1 triggers an innate immune response, however, the role of neutrophils, the most abundant white blood cells in the human circulation, in malaria remains elusive. Here we show that neutrophils recognize and kill blood stages of several P. falciparum isolates, and we identify neutrophil ICAM-1 and specific PfEMP1s implicated in cerebral malaria as the key molecules involved in this killing. Our data provide mechanistic insight into the interactions between neutrophils and iRBCs and demonstrate the important influence of PfEMP1 on the selective innate response to cerebral malaria.

microbiology↗

bioRxiv2020

The PD-L1/PD-1 Axis Blocks Neutrophil Cytotoxicity In Cancer

The PD-L1/PD-1 axis was shown to promote tumor growth and progression via the inhibition of anti-tumor immunity. Blocking this axis was shown to be beneficial in maintaining the anti-tumor functions of the adaptive immune system. Still, the consequences of blocking the PD-L1/PD-1 axis on innate immune responses remain largely unexplored. In this context, neutrophils were shown to consist of different subpopulations, which possess either pro- and anti-tumor properties. PD-L1-expressing neutrophils are considered pro-tumor as they can suppress cytotoxic T-cells. That said, we found that PD-L1 expression is not limited to tumor promoting neutrophils but is also evident in anti-tumor neutrophils. We show that neutrophil cytotoxicity is effectively and efficiently blocked by tumor cell expressed PD-1. Furthermore blocking of either neutrophil PD-L1 or tumor cell PD-1 maintains neutrophil cytotoxicity resulting in enhanced tumor cell apoptosis. Importantly, we show that tumor cell PD-1 blocks neutrophil cytotoxicity and promotes tumor growth via a mechanism independent of adaptive immunity. Taken together, these findings highlight the therapeutic potential of enhancing anti-tumor innate immune responses via blocking of the PD-L1/PD-1 axis.

immunology↗