Anti-CX3CL1 monoclonal antibody, clone 237426

The pathogenesis of inflammatory bowel disease (IBD) is associated with production of immense pro-inflammatory cytokines including TNF-alpha. Once generated, TNF-alpha stimulates production of various pro-inflammatory cytokines and disrupts mucosal barrier by inducing inflamed mucosal epithelial cell death. In the present study, we investigated inhibitory effects of TI-1-162, a hydroxyindenone derivative, against TNF-alpha-induced and TNBS-induced colon inflammation. TI-1-162 showed inhibitory effect on the TNF-alpha-induced adhesion of U937 monocytic cells to HT-29 colonic epithelial cells (IC50 = 0.83 +/- 0.12 mu M), which is an in vitro model representing the initial step of colitis. In addition, TI-1-162 suppressed TNF-alpha-stimulated caspase-3 activation and HT-29 cell apoptosis. These in vitro inhibitory activities of TI-1-162 correlated to recovery changes in in vivo colon tissues, such as downregulation of adhesion molecules (ICAM-1, VCAM-1) and chemokines (CCL11, CXCL1, CXCL2, CXCL3, CX3CL1) revealed by gene expression array and Western blot analyses. Such molecular recovery of colon epithelium from TNBS-treated rats corresponded to the recovery in body weight, colon weight/length, and myeloperoxidase level by TI-1-162 (10 and 30 mg/kg/day, orally). In relation to action mechanism, TI-1-162 did not disturb TNF-alpha binding to its receptor, but suppressed phosphorylation of RIP-1, ASK-1, JNK and p38, and nuclear translocation of NF-kB and AP-1, which corresponded to down regulation of inflammatory cytokines in TNF-alpha-treated cells (HT-29 and U937) and TNBS-treated rat colon tissues. Taken together, the results indicate that the protective effects of TI-1-162 against colon inflammation and epithelial cell death are associated with its inhibitory action in RIP/ASK-1/MAPK signaling pathway downstream to TNF receptor 1.

The malaria parasite Plasmodium falciparum traffics the virulence protein P. falciparum erythrocyte membrane protein 1 (PfEMP1) to the surface of infected red blood cells (RBCs) via membranous organelles, known as the Maurer's clefts. We developed a method for efficient enrichment of Maurer's clefts and profiled the protein composition of this trafficking organelle. We identified 13 previously uncharacterized or poorly characterized Maurer's cleft proteins. We generated transfectants expressing green fluorescent protein (GFP) fusions of 7 proteins and confirmed their Maurer's cleft location. Using co-immunoprecipitation and mass spectrometry, we generated an interaction map of proteins at the Maurer's clefts. We identified two key clusters that may function in the loading and unloading of PfEMP1 into and out of the Maurer's clefts. We focus on a putative PfEMP1 loading complex that includes the protein GEXP07/CX3CL1-binding protein 2 (CBP2). Disruption of GEXPO7 causes Maurer's cleft fragmentation, aberrant knobs, ablation of PfEMP1 surface expression, and loss of the PfEMP1-mediated adhesion. AGEXP07 parasites have a growth advantage compared to wild-type parasites, and the infected RBCs are more deformable and more osmotically fragile. IMPORTANCE The trafficking of the virulence antigen PfEMP1 and its presentation at the knob structures at the surface of parasite-infected RBCs are central to severe adhesion-related pathologies such as cerebral and placental malaria. This work adds to our understanding of how PfEMP1 is trafficked to the RBC membrane by defining the protein-protein interaction networks that function at the Maurer's clefts controlling PfEMP1 loading and unloading. We characterize a protein needed for virulence protein trafficking and provide new insights into the mechanisms for host cell remodeling, parasite survival within the host, and virulence.