Protective effect of low-level laser therapy (LLLT) on acute zymosan-induced arthritis

Lasers Med Sci. 2014 Mar;29(2):757-63. doi: 10.1007/s10103-013-1413-3. Epub 2013 Aug 10.


The aim of this study was to evaluate the effect of low-level laser therapy on acute zymosan-induced arthritis, with respect to the laser action on inflammatory cells influx, release of pro-inflammatory mediators, metalloproteinases activity into the joint cavity and the cartilage repair process. Arthritis was induced in male Wistar rats (250-280 g) by intra-articular injection of zymosan (1 mg dissolved in 50 μl of a sterile saline solution) into one rear knee joint. Animals were irradiated immediately, 1 and 2 h after zymosan administration with a semiconductor laser InGaAIP (660 nm, 10 mW, 2.5 J/cm(2), 10 s). In the positive control group, animals were injected with the anti-inflammatory drug dexamethasone 1 h prior to the zymosan administration. Treatment with laser significantly inhibited leukocytes influx, the release of IL-1 and IL-6 and also the activity of metalloproteinase-2 and 9, into the joint cavity. In conclusion, laser therapy was effective in reducing inflammation to sites of injury and inhibit activation of proteases (gelatinase) suggesting less degradation of collagen tissue in experimental model of acute arthritis.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Arthritis / chemically induced
  • Arthritis / metabolism*
  • Arthritis / pathology
  • Arthritis / radiotherapy*
  • Inflammation / metabolism
  • Interleukin-1 / metabolism
  • Interleukin-6 / metabolism
  • Leukocytes / radiation effects
  • Low-Level Light Therapy / methods
  • Male
  • Matrix Metalloproteinase 2 / metabolism
  • Matrix Metalloproteinase 9 / metabolism
  • Rats, Wistar
  • Synovial Membrane / pathology
  • Synovial Membrane / radiation effects
  • Zymosan / toxicity


  • Interleukin-1
  • Interleukin-6
  • Zymosan
  • Matrix Metalloproteinase 2
  • Matrix Metalloproteinase 9