Heparin-binding epidermal growth factor-like growth factor (HB-EGF) is increased in osteoarthritis and regulates chondrocyte catabolic and anabolic activities

Abstract

Objective We determined if the epidermal growth factor receptor ligand HB-EGF is produced in cartilage and if it regulates chondrocyte anabolic or catabolic activity. Methods HB-EGF expression was measured by quantitative PCR using RNA isolated from mouse knee joint tissues and from normal and OA human chondrocytes. Immunohistochemistry was performed on normal and OA human cartilage and meniscus sections. Cultured chondrocytes were treated with fibronectin fragments (FN-f) as a catabolic stimulus and osteogenic protein 1 (OP-1) as an anabolic stimulus. Effects of HB-EGF on cell signaling were analyzed by immunoblotting of selected signaling proteins. MMP-13 was measured in conditioned media, proteoglycan synthesis was measured by sulfate incorporation, and matrix gene expression by quantitative PCR. Results HB-EGF expression was increased in 12-month old mice at 8 weeks after surgery to induce OA and increased amounts of HB-EGF were noted in human articular cartilage from OA knees. FN-f stimulated chondrocyte HB-EGF expression and HB-EGF stimulated chondrocyte MMP-13 production. However, HB-EGF was not required for FN-f stimulation of MMP-13 production. HB-EGF activated the ERK and p38 MAP kinases and stimulated phosphorylation of Smad1 at an inhibitory serine site which was associated with inhibition of OP-1 mediated proteoglycan synthesis and reduced aggrecan (ACAN) but not COL2A1 expression. Conclusion HB-EGF is a new factor identified in OA cartilage that promotes chondrocyte catabolic activity while inhibiting anabolic activity suggesting it could contribute to the catabolic-anabolic imbalance seen in OA cartilage.

Identification of genes and pathways associated with subchondral bone in osteoarthritis via bioinformatic analysis

“…[ 27 ] Besides, related heparin binding has already been reported to contribute a lot to the catabolic–anabolic imbalance seen in OA cartilage. [ 28 ] VEGF production and inflammatory responses could be induced via RAGE receptor binding in human synoviocytes. [ 29 ] In a word, all these studies confirm our findings.…”

Molecular pathology endpoints useful for aging studies

“…Urine albumin/creatinine ratio is used to diagnose chronic kidney disease. Heparin-binding EGF is produced in cartilage, drives chondrocyte catabolic activities, and has potential as a biomarker in osteoarthritis (Long et al, 2015). Reduced proteoglycans, aggrecan, and glycosaminoglycans in discs is diagnostic of age-related intervertebral disc degeneration (Vo et al, 2013).…”

Reduced response of human meniscal cells to Osteogenic Protein 1 during osteoarthritis and pro-inflammatory stimulation

“…Cells were treated with OP1 (25–500 ng/mL for initial dose response and 100 ng/mL used for all subsequent experiments, Stryker Biotech). In signaling experiments, OP-1 stimulation was compared to IL1α, IL1β (10 ng/mL, R&D Systems), TGFβ1, IGF1 (100 ng/mL, R&D Systems), GDF5 (100 ng/mL, Prospec), or FnF (1 μM), a recombinant fragment of fibronectin protein containing domains 7–10 of full length fibronectin [20] for 24 hours or as indicated. These factors were chosen for comparison to OP1 because IL1α, IL1β, and FnF are known to stimulate MAPK signaling, TGFβ stimulates Smad2 signaling, IGF1 stimulates AKT activation, and GDF5 stimulates Smad1/5/8 signaling.…”