Microarchitecture and protective mechanisms in synovial tissue from clinically and arthroscopically normal knee joints

The effect of acute osteoarthritis (OA) on peripheral nerve fibers (NFs) in synovial tissue, and their association with histological changes were investigated in collagenase-induced OA mice. Collagenase (10 U in 5 μL saline) was injected into the right knee, and the same volume of saline was injected into the left knee as the control. Mice were sacrificed 1, 2, 3, and 4 weeks after the collagenase injection. Histopathological changes in the knee joints were evaluated. The numbers of protein gene product (PGP) 9.5-, calcitonin-gene-related peptide (CGRP)-, and substance P (SP)-positive NFs in the synovial tissue were determined, and their densities in the tissue were calculated. The densities of PGP 9.5- and CGRP-positive NFs in the synovium were drastically decreased 1 week after the collagenase injection. However, by week 4, the density of PGP 9.5- and CGRP-positive NFs had recovered to 84% and 79% of their normal levels, respectively. Despite the poor correlation between the synovitis score and the density of CGRP- or SP-positive NFs in the synovium, the ossification rate of chondrophytes in chondro/osteophyte lesions correlated strongly with the density of CGRP-positive NFs (R = 0.855). These results suggest that the ossification of chondrophytes occurred in parallel with the increase in CGRP-positive fiber density in the synovium during the acute phase of collagenase-induced OA.

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MicroRNA-26a reduces synovial inflammation and cartilage injury in osteoarthritis of knee joints through impairing the NF-κB signaling pathway

Bioscience Reports ◽

10.1042/bsr20182025 ◽

2019 ◽

Vol 39 (4) ◽

Cited By ~ 6

Author(s):

Zhi Zhao ◽

Xiu-Song Dai ◽

Zhi-Yan Wang ◽

Zheng-Qi Bao ◽

Jian-Zhong Guan

Keyword(s):

Signaling Pathway ◽

Synovial Tissue ◽

Femoral Condyle ◽

Synovial Inflammation ◽

Cartilage Injury ◽

Knee Joints ◽

Tunel Staining ◽

Protein Levels ◽

Synovial Tissues ◽

And Cartilage

Abstract Objective: Inflammation is closely implicated in the process of osteoarthritis (OA) and affects disease progression and pain. Herein, the present study explored the effect of microRNA-26a (miR-26a) on the synovial inflammation and cartilage injury in OA, with the involvement with the NF-κB signaling pathway. Methods: Rat models of OA were established by anterior cruciate ligament transection, which were then treated with miR-26a mimics/inhibitors or BMS-345541 (inhibitor of NF-κB pathway). The expression of miR-26a and activator proteins of NF-κB pathway (P-IκBα and P-P65) in synovial tissues was determined. Hematoxylin-eosin (HE) staining was adopted to observe pathological changes of knee joints, synovial tissues, and cartilage of femoral condyle. Terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL) staining was used to detect the apoptosis of synoviocytes and chondrocytes. Results: Poorly expressed miR-26a and increased protein levels of P-IκBα and P-P65 were identified in synovial tissues of OA rats. Besides, OA rats showed obvious synovial tissue hyperplasia, inflammation and cartilage injury of femoral condyle, as well as increased inflammation and cartilage injury scores, and apoptosis of synoviocytes and chondrocytes. In response to miR-26a mimics, protein levels of P-IκBα and P-P65 were reduced; meanwhile, synovial tissue hyperplasia, inflammation and cartilage injury of femoral condyle were ameliorated, with decreased inflammation and cartilage injury scores, and apoptosis of synoviocytes and chondrocytes. Conclusion: MiR-26a suppressed the activation of the NF-κB signaling pathway, by which mechanism the synovial inflammation and cartilage injury in OA rats were alleviated.

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Knee Joint Biomechanics in Physiological Conditions and How Pathologies Can Affect It: A Systematic Review

Applied Bionics and Biomechanics ◽

10.1155/2020/7451683 ◽

2020 ◽

Vol 2020 ◽

pp. 1-22 ◽

Cited By ~ 2

Author(s):

Li Zhang ◽

Geng Liu ◽

Bing Han ◽

Zhe Wang ◽

Yuzhou Yan ◽

...

Keyword(s):

Knee Joint ◽

Neurological Disorders ◽

Current Knowledge ◽

Knee Injuries ◽

Exercise Program ◽

Stair Climbing ◽

Knee Joints ◽

Future Research ◽

Normal Knee ◽

Joint Biomechanics

The knee joint, as the main lower limb motor joint, is the most vulnerable and susceptible joint. The knee injuries considerably impact the normal living ability and mental health of patients. Understanding the biomechanics of a normal and diseased knee joint is in urgent need for designing knee assistive devices and optimizing a rehabilitation exercise program. In this paper, we systematically searched electronic databases (from 2000 to November 2019) including ScienceDirect, Web of Science, PubMed, Google Scholar, and IEEE/IET Electronic Library for potentially relevant articles. After duplicates were removed and inclusion criteria applied to the titles, abstracts, and full text, 138 articles remained for review. The selected articles were divided into two groups to be analyzed. Firstly, the real movement of a normal knee joint and the normal knee biomechanics of four kinds of daily motions in the sagittal and coronal planes, which include normal walking, running, stair climbing, and sit-to-stand, were discussed and analyzed. Secondly, an overview of the current knowledge on the movement biomechanical effects of common knee musculoskeletal disorders and knee neurological disorders were provided. Finally, a discussion of the existing problems in the current studies and some recommendation for future research were presented. In general, this review reveals that there is no clear assessment about the biomechanics of normal and diseased knee joints at the current state of the art. The biomechanics properties could be significantly affected by knee musculoskeletal or neurological disorders. Deeper understanding of the biomechanics of the normal and diseased knee joint will still be an urgent need in the future.

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