Interleukin-1β-induced arthritis involves chondrocyte oxiapoptophagy.

Area of Science:

• Cell Biology
• Biochemistry
• Immunology

Background:

• Chondrocyte death contributes to arthritis pathogenesis.
• Oxysterols can induce oxiapoptophagy, a cell death pathway involving oxidative stress, apoptosis, and autophagy.
• Interleukin-1β (IL-1β) is a key pro-inflammatory cytokine implicated in joint inflammation and cartilage degradation.

Purpose of the Study:

• To investigate whether IL-1β-induced articular cartilage degeneration involves chondrocyte oxiapoptophagy.
• To elucidate the molecular mechanisms underlying IL-1β-induced chondrocyte dysfunction and cartilage damage.

Main Methods:

• Intra-articular injection of IL-1β into experimental animal knee joints.
• Analysis of cartilage explants and chondrocytes for molecular markers of degeneration, oxysterol metabolism, apoptosis, oxidative stress, and autophagy.
• Investigation of signaling pathways, including NF-κB, Akt, and mTOR.
• Pharmacological inhibition of the NF-κB pathway using CDDO-Me.

Main Results:

• IL-1β induced progressive articular cartilage degeneration and proteoglycan loss.
• IL-1β upregulated cholesterol-25-hydroxylase (CH25H) and CYP7B1, increasing 25-hydroxycholesterol (25-HC) production.
• IL-1β promoted chondrocyte apoptosis, oxidative stress (ROS), and autophagy via p53 and altered Akt/mTOR signaling.
• IL-1β activated the NF-κB pathway, which was critical for the observed molecular changes and chondrocyte damage.
• NF-κB inhibition suppressed IL-1β-induced markers of oxiapoptophagy and ROS production.

Conclusions:

• IL-1β-induced articular cartilage degeneration is mechanistically linked to chondrocyte oxiapoptophagy.
• The NF-κB signaling pathway plays a crucial role in mediating IL-1β-induced chondrocyte oxiapoptophagy and cartilage damage.
• Targeting the NF-κB pathway may offer a therapeutic strategy for IL-1β-driven arthritic conditions.