Adrenomedullin and truncated peptide adrenomedullin(22-52) affect chondrocyte response to apoptotis in vitro: downregulation of FAS protects chondrocyte from cell death

Frédéric Velard,Martine Cohen-Solal,Aurore Chatron-Colliet,Marie-Dominique Ah-Kioon,Dominique Côme,Hilène Lin,Frédéric Lioté,Hang-Korng Ea,Narjes Hafsia

doi:10.1038/s41598-020-73924-1

Abstract

Chondrocyte apoptosis may have a pivotal role in the development of osteoarthritis. Interest has increased in the use of anti-apoptotic compounds to protect against osteoarthritis development. In this work, we investigated the effect of adrenomedullin (AM), a 52 amino-acid hormone peptide, and a 31 amino-acid truncated form, AM(22-52), on chondrocyte apoptosis. Bovine articular chondrocytes (BACs) were cultured under hypoxic conditions to mimic cartilage environment and then treated with Fas ligand (Fas-L) to induce apoptosis. The expression of AM and its calcitonin receptor-like receptor (CLR)/receptor activity-modifying protein (RAMP) (receptor/co-receptor) was assessed by immunostaining. We evaluated the effect of AM and AM(22-52) on Fas-L-induced chondrocyte apoptosis. FAS expression was appreciated by RT-qPCR and immunostainings. The expression of hypoxia-inducible factor 1α (HIF-1α), CLR and one co-receptor (RAMP2) was evidenced. With BACs under hypoxia, cyclic adenosine monophosphate production increased dose-dependently with AM stimulation. AM significantly decreased caspase-3 activity (mean 35% decrease; p = 0.03) as a marker of Fas-L-induced apoptosis. Articular chondrocytes treated with AM showed significantly reduced cell death, along with downregulated Fas expression and production, as compared with AM(22-52). AM decreased articular chondrocyte apoptosis by downregulating a Fas receptor. These findings may pave the way for novel therapeutic approaches in osteoarthritis.

Highlights

Chondrocyte apoptosis may have a pivotal role in the development of osteoarthritis
Expression of functional AM receptor complex calcitonin receptor-like receptor (CLR)/RAMP2 is upregulated under hypoxia in Bovine articular chondrocytes (BACs) in vitro
In normoxia-cultured cells, hypoxia-inducible factor 1α (HIF-1α) expression was detected in cytoplasm, which was reinforced under hypoxia (Fig. 1A)

Summary

Introduction

Chondrocyte apoptosis may have a pivotal role in the development of osteoarthritis. Interest has increased in the use of anti-apoptotic compounds to protect against osteoarthritis development. Articular chondrocytes treated with AM showed significantly reduced cell death, along with downregulated Fas expression and production, as compared with AM(22-52). AM decreased articular chondrocyte apoptosis by downregulating a Fas receptor. These findings may pave the way for novel therapeutic approaches in osteoarthritis. Different effects may be attributed to AM itself depending on the models Both AM and AM(27-52) have been shown to increase bone mass and possibly cartilage thickness in normal rats[4,14], whereas AM inducible knock out or pharmacological inhibition in adult mice has been evidenced to increase bone m ass[15]. Using the murine CIA model, we demonstrated an anti-apoptotic effect of AM and AM(22-52) on articular chondrocytes, which helped decrease the severity of the experimental a rthritis[17]. We hypothesized that both peptides might affect chondrocyte death in isolated OA chondrocytes

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Conclusion