The effect of exercise on the protein profile of rat knee joint intra‐ and extra‐articular ligaments

Abstract

Injuries to the intra‐articular anterior cruciate ligament (ACL) and the extra‐articular medial collateral ligament (MCL) result in significant knee joint instability, pain, and immobility. Moderate endurance‐type exercise can increase ligament strength but little is known on the effect of short‐term regular bouts of high‐intensity exercise on the extracellular matrix (ECM) structure of knee ligaments. Therefore, this study aimed to identify the effect of short‐term regular bouts high exercise on the proteome of the rat ACL and MCL using mass spectrometry. Sprague‐Dawley male rats (n = 6) were split into control and exercise groups, and subjected to high‐intensity training for four 4 weeks followed by proteomic analyses of the ACL and MCL. Knee joint health status was assessed using OARSI and a validated histological scoring system. Histopathological analyses demonstrated no significant changes in either in cruciate, collateral ligaments, or cartilage between the control and exercised knee joints. However, significant proteins were found to be more abundant in the exercised ACL compared to ACL control group but not between the exercised MCL and control MCL groups. The significant abundant proteins in ACL exercise groups were mostly cytoskeletal, ribosomal and enzymes with several abundant matrisomal proteins such as collagen proteins and proteoglycans being found in this group. In conclusion, our results indicate that short‐term regular bouts of high‐intensity exercise have an impact on the intra‐articular ACL but not extra‐articular MCL ECM protein expression.

Age‐related changes in microRNAs expression in cruciate ligaments of wild‐stock house mice

“…Both ACLs and PCLs were scored based on strength of ECM staining, and intensified red coloration indicates an increase in proteoglycans, cell hypertrophy, abnormal increase in cell size, cell clustering loss, the disorganization of spindle‐shaped flattened cells, and predominant fibers and loss of alignment of collagen fibers. Each parameter was graded from 0 to 4 based on the extent of changes (0 = normal, 0% increased; 1 = mild abnormality, 5%–25% increase; 2 = moderate abnormality, 26%–50% increase; 3 = marked abnormality, 51%–75% increase; and 4 = severe abnormality, 76%–100% increase) (Kharaz et al, 2018 , 2021 ).…”