Osteopontin alters endothelial and valvular interstitial cell behaviour in calcific aortic valve stenosis through HMGB1 regulation

Margaret Passmore; Maria Nataatmadja; Yoke L Fung; Bronwyn Pearse; Sarah Gabriel; Peter Tesar; John F Fraser

doi:10.1093/ejcts/ezv244

Osteopontin alters endothelial and valvular interstitial cell behaviour in calcific aortic valve stenosis through HMGB1 regulation

Eur J Cardiothorac Surg. 2015 Sep;48(3):e20-9. doi: 10.1093/ejcts/ezv244.

Authors

Margaret Passmore¹, Maria Nataatmadja², Yoke L Fung³, Bronwyn Pearse⁴, Sarah Gabriel⁴, Peter Tesar⁴, John F Fraser⁵

Affiliations

¹ Critical Care Research Group, University of Queensland, Brisbane, Australia m.passmore@uq.edu.au.
² Department of Medicine, University of Queensland, Brisbane, Australia.
³ Inflammation and Healing Research Cluster, School of Health and Sport Sciences, University of the Sunshine Coast, Maroochydoore, Australia.
⁴ Cardiac Surgery Research Unit, The Prince Charles Hospital, Brisbane, Australia.
⁵ Critical Care Research Group, University of Queensland, Brisbane, Australia.

PMID: 26273067
DOI: 10.1093/ejcts/ezv244

Abstract

Objectives: Calcific aortic valve stenosis (CAVS) is an important clinical problem predominantly affecting elderly individuals. Studies suggest that the progression of CAVS is actively regulated with valve endothelial injury leading to inflammation, fibrosis and calcification. The aim of this study was to delineate the possible regulatory role of osteopontin (OPN) on high-mobility group box 1 (HMGB1) function and the associated inflammatory and fibrotic response in CAVS.

Methods: Aortic valve leaflets were collected from CAVS patients undergoing aortic valve replacement (n = 40), and control aortic valve leaflets were obtained from heart transplant recipients (n = 15). Valves and plasma were analysed by quantitative real-time polymerase chain reaction (PCR), immunohistochemical staining and Western blot. Recombinant OPN or neutralizing OPN antibody was added to cultured endothelial and valvular interstitial cells (VICs), and cell proliferation scores and HMGB1 expression were assessed.

Results: CAVS valves had a decreased total percentage of VICs but increased numbers of infiltrating macrophages relative to control valves. RT-PCR studies showed higher expression of OPN, the inflammatory cytokine tumour necrosis factor-alpha as well as markers of fibrosis, tissue inhibitor of matrix metalloproteinase 1 and matrix metalloproteinase 2 in CAVS valves. Elevated expression of OPN was also observed in plasma of CAVS patients compared with controls. HMGB1 was detected in the secretory granules of cultured valve endothelial and VICs derived from CAVS valves. The addition of exogenous OPN inhibited the proliferation of cultured endothelial and VICs from CAVS valves and was associated with the extracellular expression of HMGB1, whereas neutralizing OPN had the opposite effect.

Conclusions: We conclude that altered OPN expression in CAVS affects cellular HMGB1 function inducing cytoplasmic translocation and secretion of HMGB1 in endothelial cells and VICs, thus indicating a regulatory role for OPN in the progression of CAVS through alteration of HMGB1 function.

Keywords: Calcific aortic valve stenosis; Endothelial cells; HMGB1; Osteopontin; Valvular interstitial cells.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Adult
Aged
Aged, 80 and over
Aortic Valve / pathology*
Aortic Valve Stenosis / etiology*
Aortic Valve Stenosis / pathology
Blotting, Western
Calcinosis / etiology*
Calcinosis / pathology
Case-Control Studies
Endothelium, Vascular / pathology
Female
HMGB1 Protein / physiology*
Humans
Male
Middle Aged
Osteopontin / physiology*
Real-Time Polymerase Chain Reaction
Young Adult

Substances

HMGB1 Protein
HMGB1 protein, human
Osteopontin

Supplementary concepts

Aortic Valve, Calcification of