Macrophage TGF-<i>β</i>1 and the Proapoptotic Extracellular Matrix Protein BIGH3 Induce Renal Cell Apoptosis in Prediabetic and Diabetic Conditions

Abstract

Metabolically stressed kidney is in part characterized by infiltrating macrophages and macrophage-derived TGF-β1 that promote the synthesis of various ECM molecules. TGF-β1 strongly enhances the expression of the gene TGFBI that encodes a cell-adhesion class, proapoptotic ECM protein called BIGH3. We hypothesized that in a diabetic environment a relationship between infiltrating macrophages, macrophage-derived TGF-β1, and BIGH3 protein promotes renal cell death. To investigate this hypothesis, we used our mouse model of diabetic complications. Mice on a high-fat diet developed hypercholesterolemia, and exposure to streptozotocin rendered hypercholesterolemic mice diabetic. Immunohistochemical images show increased macrophage infiltration and BIGH3 protein in the kidney cortices of hypercholesterolemic and diabetic mice. Macrophages induced a two-fold increase in BIGH3 expression and an 86% increase in renal proximal tubule epithelial cell apoptosis. TGF-β1 antibody and TGF-β1 receptor chemical antagonist blocked macrophage-induced apoptosis. BIGH3 antibody completely blocked apoptosis that was induced by TGF-β1, and blocked apoptosis induced by exogenous recombinant BIGH3. These results uncover a distinctive interplay of macrophage-derived TGF-β1, BIGH3 protein, and apoptosis, and indicate that BIGH3 is central in a novel pathway that promotes diabetic nephropathy. Macrophage TGF-β1 and BIGH3 are identified as prediabetic biomarkers, and potential therapeutic targets for intervention in prediabetic and diabetic individuals.

BIGH3: A Negative Regulator of Human Osteosarcoma Large Multicellular Spheroids

“…We employed a liquid-aga-rose overlay paradigm that promoted the formation of MTS. Using TUNEL assays, we previously published findings that TGFβ1 significantly increased BIGH3 expression and apoptosis in monolayers of osteosarcoma MG-63 and Saos-2 cells [11], retinal endothelial cells [44], retinal pericytes [45], and renal tubule epithelial cells [46]. Others have shown BIGH3-mediated apoptosis in CHO and lung adenocarcinoma cells [47], HeLa and transformed corneal epithelial cells [48].…”

TGFβ induces BIGH3 expression and human retinal pericyte apoptosis: a novel pathway of diabetic retinopathy

“…Rhesus RECs (RhRECs), primary renal proximal tubule epithelial cells, and cell media were described in a previous publication from our laboratories. 14,21 Transforming growth factor β TGFβ1 and TGFβ2 were purchased from Sigma Aldrich (Cat No: T7039, T2815; St. Louis, MO USA).…”

“…The resultant anti-BIGH3 antiserum has been previously characterized. 16,21 Preimmune serum was used as negative control where indicated in the individual experiments. Anti-rat CD68 antibody was obtained from ABD seroTec (Cat No.…”

“…To test if the pathway reported in previous publications 14,21 was also a valid pathway for retinal pericytes, HRP were cultured in cell medium containing 5 ng/ml of TGFβ1 or 2, with or without rabbit anti-BIGH3 antiserum (BIGH3 Ab). To determine if BIGH3 could induce HRP apoptosis, cells were treated with increasing concentrations of recombinant BIGH3.…”

“…To determine if BIGH3 could induce HRP apoptosis, cells were treated with increasing concentrations of recombinant BIGH3. 21 In one part of this study, cells were incubated with increasing concentrations of BIGH3 for 24 h and TUNEL assays were performed to determine cell death. We next compared the sensitivity of different cell types for BIGH3-induced cell death.…”