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Effect of Continuous-Wave Low-Intensity Ultrasound in Inflammatory Resolution of Arthritis-Associated Synovitis.
- Source :
-
Physical Therapy . Jun2016, Vol. 96 Issue 6, p808-817. 10p. - Publication Year :
- 2016
-
Abstract
- Background. Low-intensity ultrasound (LUIS) can reduce pain and improve function in arthritic joints. Neutrophils are first-line actors in host defense that recruit macrophages. Dead neutrophils are removed during resolution of inflammation. Delayed neutrophil clearance can lead to extended inflammation or even chronic autoimmune disease. Although neutrophil extracellular traps (NETs) in arthritic tissue are involved in the pathogenesis of arthritis, their functional role has not been clarified. Objectives. This study aimed to investigate the effect of LUIS on synovial inflammation and its resolution via neutrophil clearance. Methods. Synovitis was induced by intra-articular injection of complete Freund's adjuvant (CFA) into the left knee joint of 58 adult male Sprague-Dawley rats. Low-intensity ultrasound (1 MHz, 200 mW/cm") was applied for 10 minutes daily. Neutrophil clearance was assessed with the expression of myeloperoxidase (MPO). In addition, terminal deoxynucleotidyl trans-ferase dUTP nick end labeling (TUNEL) staining and NET formation in the synovium were observed. In neutrophil and macrophage cultures from peripheral blood, the effect of NET clearance by LUIS was investigated. Results. In CFA-induced synovitis, MPO-positive neutrophils peaked after 2 to 3 days, filling the inflammatory core. Monocytes and macrophages in the periphery later infiltrated the core and were reduced thereafter. Low-intensity ultrasound reduced synovial hyperplasia and induced earlier MPO clearance. Neutrophils in the core of the inflamed synovium exhibited NET formation, which LIUS increased. Low-intensity also induced NETs in peripheral poly-morphonuclear cells in an intensity-dependent manner and potentiated phorbol myristate acetate (PMA)-induced NETosis. The PMA-induced NETs were cleared by macrophages; clearance was enhanced by LIUS. Limitations. The effect of LIUS on CFA-induced inflammation was observed only during the acute phase. Although the effect of LIUS on NETosis in the in vitro neutrophil culture system was clear, the in vivo NETosis cannot be quantified. Conclusions. Neutrophil extracellular traps act in inflammatory synovitis, and LIUS enhanced the NETs and resulted in neutrophil clearance by enhancing the phagocytosis of macrophages, which might be a factor underlying the therapeutic effect of LIUS in arthritic synovium. [ABSTRACT FROM AUTHOR]
- Subjects :
- *ANIMAL experimentation
*APOPTOSIS
*ARTHRITIS
*CELL culture
*IMMUNOHISTOCHEMISTRY
*HEALTH outcome assessment
*NEUTROPHILS
*PROBABILITY theory
*RATS
*RESEARCH funding
*STATISTICAL hypothesis testing
*ULTRASONIC therapy
*WESTERN immunoblotting
*DATA analysis software
*SYNOVITIS
*DESCRIPTIVE statistics
*MANN Whitney U Test
*KRUSKAL-Wallis Test
*DISEASE complications
*THERAPEUTICS
*PHYSIOLOGY
Subjects
Details
- Language :
- English
- ISSN :
- 00319023
- Volume :
- 96
- Issue :
- 6
- Database :
- Academic Search Index
- Journal :
- Physical Therapy
- Publication Type :
- Academic Journal
- Accession number :
- 115790598
- Full Text :
- https://doi.org/10.2522/ptj.20140559