SUMMARY Plasmodium falciparum engineer infected erythrocytes to present the malarial protein, VAR2CSA, which binds a distinct type chondroitin sulfate (CS) exclusively expressed in the placenta. Here, we show that the same CS modification is present on a high proportion of malignant cells and that it can be specifically targeted by recombinant VAR2CSA (rVAR2). In tumors, placental-like CS chains are linked to a limited repertoire of cancer-associated proteoglycans including CD44 and CSPG4. The rVAR2 protein localizes to tumors in vivo and rVAR2 fused to diphtheria toxin or conjugated to hemiasterlin compounds strongly inhibits in vivo tumor cell growth and metastasis. Our data demonstrate how an evolutionarily refined parasite-derived protein can be exploited to target a common, but complex, malignancy-associated glycosaminoglycan modification.

The seven transmembrane G protein-coupled receptor EBV-induced gene 2 (EBI2), also known as GPR183, is expressed in particular in immune cells. Activated by its endogenous ligands, which are a group of oxysterols, it functions as a chemo-attractant receptor, mediating cell migration. In coordination with other receptors, EBI2 plays important roles in controlling the migration of immune cells during the course of a T-dependent Ab response in the spleen. In recent years, it has become clear that EBI2 also has other roles to play in the immune system. Thus, EBI2 seems to be involved in innate immune responses, such as those mediated by TLR signaling, and it has been implicated in regional immune responses, including immune responses in the CNS. In this review, we describe the functions of EBI2 in B cells, T cells, and dendritic cells during the course of a T-dependent Ab response in the spleen. Furthermore, we review the existing evidence supporting a role for EBI2 in local immune responses and in autoimmune diseases, with a special focus on immune responses in the CNS. Finally, we discuss which type of role EBI2 may play in autoimmune diseases, and we give our opinion about the paths of future research in EBI2.

Chemokine receptors play important roles in the immune system and are linked to several human diseases. The initial contact of chemokines with their receptors depends on highly specified extracellular receptor features. Here we investigate the importance of conserved extracellular disulfide bridges and aromatic residues in extracellular loop 2 (ECL-2) for ligand binding and activation in the chemokine receptor CCR8. We used inositol 1,4,5-trisphosphate accumulation and radioligand binding experiments to determine the impact of receptor mutagenesis on both chemokine and small molecule agonist and antagonist binding and action in CCR8. We find that the seven-transmembrane (TM) receptor conserved disulfide bridge (7TM bridge) linking transmembrane helix III (TMIII) and ECL-2 is crucial for chemokine and small molecule action, whereas the chemokine receptor conserved disulfide bridge between the N terminus and TMVII is needed only for chemokines. Furthermore, we find that two distinct aromatic residues in ECL-2, Tyr 184 (Cys ؉ 1) and Tyr 187 (Cys ؉ 4), are crucial for binding of the CC chemokines CCL1 (agonist) and MC148 (antagonist), respectively, but not for small molecule binding. Finally, using in silico modeling, we predict an aromatic cluster of interaction partners for Tyr 187 in TMIV (Phe 171 ) and TMV (Trp 194 ). We show in vitro that these residues are crucial for the binding and action of MC148, thus supporting their participation in an aromatic cluster with Tyr 187 . This aromatic cluster appears to be present in a large number of CC chemokine receptors and thereby could play a more general role to be exploited in future drug development targeting these receptors.Chemokines (chemotactic cytokines) regulate the differentiation, activation, and recruitment of leukocytes. They also play important roles in several physiological mechanisms outside the immune system such as organogenesis and angiogenesis (1, 2). With ϳ50 members, these cytokines exert their effects through chemokine receptors (23 members), which belong to class A of the family of seven-transmembrane (7TM) 2 G protein-coupled receptors (3). The implications of the chemokine system in a vast number of human diseases (3) have increased the interest in developing potent, selective, and clinically useful chemokine receptor antagonists.The binding of a chemokine to its cognate receptor is initially driven by electrostatic interactions between the overall positively charged chemokine and the negatively charged extracellular surface of the receptor. Then interactions between the chemokine N terminus and residues in the main binding pocket of the receptor trigger receptor activation (4 -6). In contrast, small molecule ligands bind deeper in the main binding pocket and constrain the receptors in either active or inactive conformations (7,8). Whereas most mapping studies of small molecules have focused on the transmembrane areas, newer studies as well as crystal structures of class A receptors suggest that extracellular receptor regions, in particular ex...

Human and mouse chronic lymphocytic leukemia (CLL) develops from CD5 B cells that in mice and macaques are known to define the distinct B1a B-cell lineage. B1a cells are characterized by lack of germinal center (GC) development, and the B1a cell population is increased in mice with reduced GC formation. As a major mediator of follicular B-cell migration, the G protein-coupled receptor Epstein-Barr virus-induced gene 2 ( or ) directs B-cell migration in the lymphoid follicles in response to its endogenous ligands, oxysterols. Thus, upregulation of EBI2 drives the B cells toward the extrafollicular area, whereas downregulation is essential for GC formation. We therefore speculated whether increased expression of EBI2 would lead to an expanded B1 cell subset and, ultimately, progression to CLL. Here, we demonstrate that B-cell-targeted expression of human EBI2 (hEBI2) in mice reduces GC-dependent immune responses, reduces total immunoglobulin M (IgM) and IgG levels, and leads to increased proliferation and upregulation of cellular oncogenes. Furthermore, hEBI2 overexpression leads to an abnormally expanded CD5 B1a B-cell subset (present as early as 4 days after birth), late-onset lymphoid cancer development, and premature death. These findings are highly similar to those observed in CLL patients and identify EBI2 as a promoter of B-cell malignancies.