Effective protein extraction combined with data independent acquisition analysis reveals a comprehensive and quantifiable insight into the proteomes of articular cartilage and subchondral bone.

This research article is about the development of a method to map the articular cartilage and subchondral bone proteins quantitatively using a high throughput method, presented through the study of horses. This can lead to a better understanding of osteoarthritis development.

Research Objective

• The primary objective is to create a sensitive, reproducible method capable of mapping the proteins in articular cartilage and subchondral bone, which could aid in understanding the pathogenesis of Osteoarthritis (OA).
• The secondary goal is to identify proteins of particular interest that could be implicated in the development of OA.

Research Methodology

• The study used horses as model animals.
• Protein extraction was carried out from samples of articular cartilage and subchondral bone using ultrasonication or pressure cycling technology.
• A proteomics analytical technique called data independent acquisition based mass spectrometry was used to study the proteins extracted.
• A pre-existing spectral library served as the reference database, with a false discovery rate of 1%.

Results

• The researchers were able to identify a comprehensive quantitative cartilage (1758 proteins) and subchondral bone (1482 proteins) proteomes, which is the largest set for these species to date.
• The protein extraction methods were found to be reproducible and sensitive, indicating a high consistency (>97% overlap) among the identified proteins.
• Proteome mining highlighted a significant count of quantifiable proteins associated with cartilage, bone matrix, osteogenesis, and bone remodeling. Proteins included ACAN, BGN, PRELP, FMOD, COMP, ACP5, BMP3, BMP6, BGLAP, TGFB1, IGF1, ALP, MMP3, and collagens.
• Some proteins were identified in distinct protein isoforms with potentially unique biological roles, such as COMP and TNN.

Implications

• The successful development of two reproducible and sensitive workflows enables a comprehensive quantitative insight into the proteomes of cartilage and subchondral bone in any species.
• This advancement opens the potential for future studies to better understand the molecular events within the osteochondral unit contributory to the pathogenesis of OA.