A Fully Human Monoclonal Antibody (CR002) Identifies PDGF-D as a Novel Mediator of Mesangioproliferative Glomerulonephritis

Abstract

Abstract. PDGF-B is of central importance in mesangioproliferative diseases. PDGF-D, a new PDGF isoform, like PDGF-B, signals through the PDGF ␤␤-receptor. The present study first determined that PDGF-D is mitogenic for rat mesangial cells and is not inhibited by a PDGF-B antagonist. Low levels of PDGF-D mRNA were detected in normal rat glomeruli. After induction of mesangioproliferative nephritis in rats by anti-Thy 1.1 mAb, glomerular PDGF-D mRNA and protein expression increased significantly from days 4 to 9 in comparison with nonnephritic rats. Peak expression of PDGF-D mRNA occurred 2 d later than peak PDGF-B mRNA expression. In addition, PDGF-D serum levels increased significantly in the nephritic animals on day 7. For investigating the functional role of PDGF-D, neutralizing fully human mAb were generated using the XenoMouse technology. Rats with anti-Thy 1.1-induced nephritis were treated on days 3 and 5 with different amounts of a fully human PDGF-DDspecific neutralizing mAb (CR002), equal amounts of irrelevant control mAb, or PBS by intraperitoneal injection. Specific antagonism of PDGF-D led to a dose-dependent (up to 67%) reduction of glomerular cell proliferation. As judged by double immunostaining for 5-bromo-2'-deoxyuridine and ␣-smooth muscle actin, glomerular mesangial cell proliferation was reduced by up to 57%. Reduction of glomerular cell proliferation in the rats that received CR002 was not associated with reduced glomerular expression of PDGF-B mRNA. PDGF-D antagonism also led to reduced glomerular infiltration of monocytes/macrophages (day 5) and reduced accumulation of fibronectin (day 8). In contrast, no effect was noted in normal rats that received an injection of CR002. These data show that PDGF-D is overexpressed in mesangioproliferative states and can act as an auto-, para-, or even endocrine glomerular cell mitogen, indicating that antagonism of PDGF-D may represent a novel therapeutic approach to mesangioproliferative glomerulonephritides.

Intrarenal Injection of Bone Marrow-Derived Angiogenic Cells Reduces Endothelial Injury and Mesangial Cell Activation in Experimental Glomerulonephritis

“…Glomerular infiltration of macrophages was determined by counting the number of ED-1-positive cells according to a previously described method (19), with minor modification. Deparaffinized sections, 4 m thick, were stained with mouse anti-rat macrophage monoclonal antibody, clone ED-1 (Chemicon International, Temecula, CA) at a dilution of 1:100.…”

Antagonism of PDGF-D by Human Antibody CR002 Prevents Renal Scarring in Experimental Glomerulonephritis

“…Ample evidence now is available to link the PDGF system to these processes. The role of PDGF-B chain in mediating mesangioproliferative changes is well established (4 -6), but the role of PDGF-D has been elucidated only recently (7)(8)(9)(10). Like PDGF-B, PDGF-D signals through the PDGF-␤ receptor (7,8).…”

“…PDGF-D induces mesangial cell proliferation in vitro and is overexpressed in mesangioproliferative glomerulonephritis in vivo (9). Adenoviral expression of PDGF-D in the liver induced prominent mesangioproliferative nephritis in mice (10).…”

“…Adenoviral expression of PDGF-D in the liver induced prominent mesangioproliferative nephritis in mice (10). PDGF-␤ receptor knockout mice fail to develop a mesangium (12), and, finally, specific antagonism of PDGF-D chain with the fully human mAb CR002 reduced mesangial cell proliferation and matrix accumulation in a (reversible, nonprogressive) rat model of mesangioproliferative nephritis, the anti-Thy-1.1 model (9).…”

Glomerulonephritis, Pathogenetic Mechanisms and Therapeutic Options: An Overview

“…Two daily doses of this aptamer induced a 95% reduction of proliferation of mesangial cells typical model GN by anti -Thy 1.1. Recently, the results were confirmed with use of recombinant human monoclonal antibodies directed against PDGF [13,59].…”