Effect of low-level laser therapy on the expression of inflammatory mediators and on neutrophils and macrophages in acute joint inflammation

• Published in: Arthritis research & therapy Vol. 15; no. 5; p. R116
• Main Authors: Alves, Ana Carolina Araruna, Vieira, Rodolfo de Paula, Leal-Junior, Ernesto Cesar Pinto, dos Santos, Solange Almeida, Ligeiro, Ana Paula, Albertini, Regiane, Junior, Jose Antonio Silva, de Carvalho, Paulo de Tarso Camillo
• Format: Journal Article
• Language: English
• Published: London BioMed Central 12.09.2013; BioMed Central Ltd
• Subjects: Acute Disease; Animals; Arthritis - chemically induced; Arthritis - genetics; Arthritis - radiotherapy; Care and treatment; Cytokines - genetics; Cytokines - metabolism; Dose-Response Relationship, Radiation; Enzyme-Linked Immunosorbent Assay; Euthanasia; Gene Expression - radiation effects; Health aspects; Inflammation; Inflammation Mediators - metabolism; Interleukin-1beta - genetics; Interleukin-1beta - metabolism; Interleukin-6 - genetics; Interleukin-6 - metabolism; Interleukins; Knee Joint - metabolism; Knee Joint - pathology; Knee Joint - radiation effects; Lasers in surgery; Low-Level Light Therapy - methods; Macrophages - metabolism; Macrophages - radiation effects; Male; Mediators; Medicine; Medicine & Public Health; Neutrophils - metabolism; Neutrophils - radiation effects; Orthopedics; Osteoarthritis; Papain; Random Allocation; Rats; Rats, Wistar; Research Article; Reverse Transcriptase Polymerase Chain Reaction; Rheumatology; RNA; Treatment Outcome; Tumor necrosis factor; Tumor Necrosis Factor-alpha - metabolism; California; Papain; Dilate Blood Vessel; Synovial Membrane; Burning Mouth Syndrome; Injury Group
• ISSN: 1478-6354; 1478-6362; 1478-6354; 1478-6362
• DOI: 10.1186/ar4296

Introduction Inflammation of the synovial membrane plays an important role in the pathophysiology of osteoarthritis (OA). The synovial tissue of patients with initial OA is characterized by infiltration of mononuclear cells and production of proinflammatory cytokines and other mediators of joint injury. The objective was to evaluate the effect of low-level laser therapy (LLLT) operating at 50 mW and 100 mW on joint inflammation in rats induced by papain, through histopathological analysis, differential counts of inflammatory cells (macrophages and neutrophils), as well as gene expression of interleukin 1-beta and 6 (IL-1β and IL-6), and protein expression of tumor necrosis factor alpha (TNFα). Methods Male Wistar rats ( n = 60) were randomly divided into four groups of 15 animals, namely: a negative control group; an inflammation injury positive control group; a 50 mW LLLT group, subjected to injury and treated with 50 mW LLLT; and a 100 mW LLLT group, subjected to injury and treated with 100 mW LLLT. The animals were subject to joint inflammation (papain solution, 4%) and then treated with LLLT (808 nm, 4 J, 142.4 J/cm 2 , spot size 0.028 for both groups). On the day of euthanasia, articular lavage was collected and immediately centrifuged; the supernatant was saved for analysis of expression of TNFα protein by enzyme-linked immunosorbent assay and expression of IL-1β and IL-6 mRNA by real-time polymerase chain reaction. A histologic examination of joint tissue was also performed. For the statistical analysis, analysis of variance with Tukey's post-hoc test was used for comparisons between each group. All data are expressed as mean values and standard deviation, with P < 0.05. Results Laser treatment with 50 mW was more efficient than 100 mW in reducing cellular inflammation, and decreased the expression of IL-1β and IL-6. However, the 100 mW treatment led to a higher reduction of TNFα compared with the 50 mW treatment. Conclusions LLLT with 50 mW was more efficient in modulating inflammatory mediators (IL-1β, IL-6) and inflammatory cells (macrophages and neutrophils), which correlated with the histology that showed a reduction in the inflammatory process.