Plasmodium falciparum infected erythrocytes can bind to host receptors integrins αVβ3 and αVβ6 through DBLδ1_D4 domain of PFL2665c PfEMP1 protein

Abstract

Major complications and mortality from Plasmodium falciparum malaria are associated with cytoadhesion of parasite-infected erythrocytes (IE). The main parasite ligands for cytoadhesion are members of the P. falciparum erythrocyte membrane protein 1 (PfEMP1) family. Interactions of different host receptor-ligand pairs may lead to various pathological outcomes, like placental or cerebral malaria. It has been shown previously that IE can bind integrin αVβ3. Using bead-immobilized PfEMP1 constructs, we have identified that the PFL2665c DBLδ1_D4 domain binds to αVβ3 and αVβ6. A parasite line expressing PFL2665c binds to surface-immobilized αVβ3 and αVβ6; both are RGD motif-binding integrins. Interactions can be inhibited by cyloRGDFV peptide, an antagonist of RGD-binding integrins. This is a first, to the best of our knowledge, implication of a specific PfEMP1 domain for binding to integrins. These host receptors have important physiological functions in endothelial and immune cells; therefore, these results will contribute to future studies and a better understanding, at the molecular level, of the physiological outcome of interactions between IE and integrin receptors on the surface of host cells.

Structural insights into diverse modes of ICAM-1 binding by Plasmodium falciparum -infected erythrocytes

“…PfEMP1 bind to a variety of human ligands (11, 12), the most common of which are cluster of differentiation 36 (CD36), endothelial protein C receptor (EPCR), and intercellular adhesion molecule 1 (ICAM-1) (13–15). Group B and C (BC) PfEMP1 that contain cysteine-rich interdomain region (CIDR) α2 to α6 domains bind to CD36 and are associated with parasites which cause mild or uncomplicated malaria (16, 17) while the A-type PfEMP1 that contain CIDRα1 domains that bind to EPCR are associated with severe childhood malaria (14, 18–21).…”

Comprehensive analysis of Fc-mediated IgM binding to the Plasmodium falciparum erythrocyte membrane protein 1 family in three parasite clones

“…In a complementary approach, we tested a BioPlex bead array composed of 157 recombinant proteins representing almost all DBL and CIDR domains in the PfEMP1 proteins of P. falciparum 3D7 for binding by non-immune IgM, in a manner similarly to that used previously in tests of PfEMP1 binding to the endothelial receptors ICAM-1, CD36, and αVβ3 and αVβ6 integrins 25–27 . By this method, evidence of non-immune IgM binding was found in constructs from 13 PfEMP1 variants in P. falciparum 3D7 (Fig.…”

“…S1) for IE surface expression of the corresponding native protein and test their IgM-binding capacity (Figs 5 and S7). In the other approach, we made use of a protein array containing constructs representing almost all PfEMP1 domains or domain tandems (DBL-CIDR) in P. falciparum 3D7, immobilized on BioPlex beads 26,27 (Fig. S5).…”

“…Non-immune IgM-binding to recombinant PfEMP1 domains from P. falciparum 3D7 was also assessed by recombinant protein micro-array as previously described 26,27 . In brief, single- or multi-domain proteins were expressed in COS7 cells, purified and immobilized on BioPlex beads as described before 25 .…”

“…Uniform coating of the beads was verified using biotinylated anti-GFP antibody (Abcam), followed by incubation with streptavidin-PE (1:250; Jackson Immunoresearch). Non-immune IgM (10 nM; Sigma) binding to bead-bound PfEMP1 constructs (1,000 to 2,000 beads in the reaction) was measured in duplicates on BioPlex 200 machine (BioRad) as described before 25,27 . Binding of non-immune IgM to the constructs were determined by incubation with PE-conjugated anti-human IgM (1:250; Jackson Immunoresearch).…”