title: Effect of low-level laser therapy on the expression of inflammatory mediators and on neutrophils and macrophages in acute joint inflammation.
abstract: BACKGROUND
  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.
authors.forename: Ana Carolina
authors.initials: AC
authors.lastname: Alves
authors.forename: Rodolfo
authors.initials: R
authors.lastname: Vieira
authors.forename: Ernesto
authors.initials: E
authors.lastname: Leal-Junior
authors.forename: Solange
authors.initials: S
authors.lastname: dos Santos
authors.forename: Ana Paula
authors.initials: AP
authors.lastname: Ligeiro
authors.forename: Regiane
authors.initials: R
authors.lastname: Albertini
authors.forename: Jose
authors.initials: J
authors.lastname: Junior
authors.forename: Paulo
authors.initials: P
authors.lastname: de Carvalho
mesh_terms: D000208:Acute Disease; D000818:Animals; D001168:Arthritis / Q000139:chemically induced / Q000235:genetics / Q000532:radiotherapy*; D016207:Cytokines / Q000235:genetics* / Q000378:metabolism; D004307:Dose-Response Relationship, Radiation; D004797:Enzyme-Linked Immunosorbent Assay; D015870:Gene Expression / Q000528:radiation effects*; D018836:Inflammation Mediators / Q000378:metabolism; D053583:Interleukin-1beta / Q000235:genetics / Q000378:metabolism; D015850:Interleukin-6 / Q000235:genetics / Q000378:metabolism; D007719:Knee Joint / Q000378:metabolism / Q000473:pathology / Q000528:radiation effects; D028022:Low-Level Light Therapy / Q000379:methods*; D008264:Macrophages / Q000378:metabolism / Q000528:radiation effects*; D008297:Male; D009504:Neutrophils / Q000378:metabolism / Q000528:radiation effects*; D010206:Papain; D011897:Random Allocation; D051381:Rats; D017208:Rats, Wistar; D020133:Reverse Transcriptase Polymerase Chain Reaction; D016896:Treatment Outcome; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism
chemical_list: D016207:Cytokines; D018836:Inflammation Mediators; D053583:Interleukin-1beta; D015850:Interleukin-6; D014409:Tumor Necrosis Factor-alpha; D010206:Papain
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