Src-family kinase signaling modulates the adhesion ofPlasmodium falciparum on human microvascular endothelium under flow

Abstract

The pathogenicity of Plasmodium falciparum is due to the unique ability of infected erythrocytes (IRBCs) to adhere to vascular endothelium. We investigated whether adhesion of IRBCs to CD36, the major cytoadherence receptor on human dermal microvascular endothelial cells (HDMECs), induces intracellular signaling and regulates adhesion. A recombinant peptide corresponding to the minimal CD36-binding domain from P falciparum erythrocyte membrane protein 1 (PfEMP1), as well as an anti-CD36 monoclonal antibody (mAb) that inhibits IRBC binding, activated the mitogen-activated protein (MAP) kinase pathway that was dependent on Src-family kinase activity. Treatment of HDMECs with a Src-family kinase-selective inhibitor (PP1) inhibited adhesion of IRBCs in a flow-chamber assay by 72% (P < .001). More importantly, Src-family kinase activity was also required for cytoadherence to intact human microvessels in a human/severe combined immunodeficient (SCID) mouse model in vivo. The effect of PP1 could be mimicked by levamisole, a specific alkaline-phosphatase inhibitor. Firm adhesion to PP1-treated endothelium was restored by exogenous alkaline phosphatase. In contrast, inhibition of the extracellular signal-regulated kinase 1/2 (ERK 1/2) and p38 MAP kinase pathways had no immediate effect on IRBC adhesion. These results suggest a novel mechanism for the modulation of cytoadherence under flow conditions through a signaling pathway involving CD36, Src-family kinases, and an ectoalkaline phosphatase. Targeting IntroductionThe adhesion of infected erythrocytes (IRBCs) containing mature stages of the parasite Plasmodium falciparum to host endothelium is a key pathogenic process of the infection. 1 The resulting sequestration of IRBCs in the microvasculature can lead to tissue hypoxia, metabolic disturbances, multiorgan dysfunction, and ultimately the death of 1 to 2 million patients worldwide annually. 2 Cytoadherence is mediated by the parasite protein P falciparum erythrocyte membrane protein 1 (PfEMP1) 3 and endothelial receptor molecules, including CD36, 4,5 intercellular adhesion molecule 1 (ICAM-1), 6 E-selectin, and vascular cell adhesion molecule 1 (VCAM-1). 7 Under physiologic flow conditions, IRBCs have been shown to interact synergistically with the different adhesion molecules on microvascular endothelium in a shear-dependent manner, 8,9 mimicking the adhesive events of the leukocyte recruitment cascade. 10 IRBCs tether and roll on ICAM-1, 8,9 VCAM-1, 8 and P-selectin. 8 These low-affinity interactions by themselves are not sufficient for the arrest of the rolling cells, but they enhance the subsequent adhesion of almost all clinical parasite isolates tested to CD36. 8,9 Peptide-mapping studies on CD36 reveal that residues 145 to 171, 11 and to a lesser extent 97 to 110, 12 are important for IRBC adhesion, while the critical region of PfEMP1 involved in binding to CD36 is localized to a 179-amino acid sequence within the cysteine-rich interdomain region 1 (CIDR1). 13 The above investigations focused on the extracell...

Metabolic Acidosis Induced by Plasmodium Falciparum Intraerythrocytic Stages Alters Blood—Brain Barrier Integrity

“…Previous studies, performed using cultures of human umbilical vein EC, human dermal microvascular EC, human pulmonary EC, or animal cerebral EC lines, have suggested that PRBCs cytoadherence to EC could induce a BBB alteration via activation of intracellular signaling pathways, which leads to changes in the expression of surface adhesion molecule, release of immunoregulatory molecules, and junctions opening (Gillrie et al, 2007;Jenkins et al, 2007;Taoufiq et al, 2008;Yipp et al, 2003). In contrast, in the hCMEC/D3 model, our results showed that alteration of the paracellular permeability can be induced with noncytoadherent PRBCs, as observed in primary brain EC (Tripathi et al, 2007) or even when the PRBCs are not in contact with the cells.…”

“…To overcome this limitation, recent studies have used primary EC from either animal origin, such as porcine (Treeratanapiboon et al, 2005), simian cells (Gay et al, 1995), or human origin from different organs, including skin (Yipp et al, 2003), lung (Taoufiq et al, 2008), and brain (Tripathi et al, 2007). Nevertheless, the procedure of cell isolation remains a delicate and time-consuming step.…”

Current Advances in Cerebral Malaria Associated Encephalopathy

“…Src-family kinase signaling was found to modulate the adhesion of P. falciparum on human microvasculature (Yipp, Robbins et al 2003;Gillrie, Krishnegowda et al 2007). A novel mechanism for the regulation of pRBCs adhesion on human microvascular endothelial cells is through CD36, Src-family kinase, and ectoalkaline phosphatase (Yipp, Robbins et al 2003).…”

“…In murine models, apoptosis occurs in endothelial cells first, and is followed by neuronal and glia cells (Lackner, Burger et al 2007). P. falciparum-pRBCs increase the expression of ICAM-1 and CD36 (Collins, Read et al 1995;Tripathi, Sullivan et al 2006;Tripathi, Sha et al 2009) which strengthens sequestration, probably through NF-kappa B (Collins, Read et al 1995;Tripathi, Sullivan et al 2006;Tripathi, Sha et al 2009) and MAP Kinase activation (Yipp, Robbins et al 2003). In addition, pRBC adhesion to endothelium was found to up regulate several TNFsuperfamily genes and apoptosis-related genes such as Bad, Bax, caspase-3, SARP2, DFF45/ICAD, IFN-g receptor2, Bcl-w, Bik, and iNOS (Pino, Vouldoukis et al 2003).…”

“…The proinflammaotry NF-kappaB pathway (Tripathi, Sha et al 2009;Labbe, Miu et al 2010), Src family kinase (Yipp, Robbins et al 2003;Gillrie, Krishnegowda et al 2007) and Rho kinase (Taoufiq, Gay et al 2008) play certain roles in modulating the host response to P. falciparum, especially in the interaction between sequestered pRBC and specific endothelium [ Fig. 2, Adapted with permission from Cytokine and Growth Review (Liu, Guo et al 2011)].…”