Low-intensity laser therapy efficacy evaluation in FVB mice subjected to acute and chronic arthritis
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Rheumatoid arthritis, an autoimmune inflammation, has a high prevalence in the population, and while therapy is available, it required often injection of drugs causing discomfort to patients. This study evaluates the clinical and histological effect of low-intensity laser therapy (LILT) as an alternative treatment, in a murine model of acute and chronic inflammation. FVB mice received either a Zymosan A injection into one knee joint inducing acute inflammation, followed after 15 min or 24 h by LILT or a collagen bovine type II injection emulsified in “Freund’s Complete Adjuvant” to induce chronic arthritis, followed at 4 weeks with multiple LILT sessions. LILT mediated by either 660, 808, or 905 nm and tissue response was evaluated based on clinical symptoms and histological analysis of inflammatory infiltrate and damage to the articular surfaces. LILT can be effective in elevating clinical symptoms, so Kruskal-Wallis testing indicated no significant differences between knees affected by acute arthritis and treated once with LILT and an injured knee without treatment (p > 0.05) for 660 and 808 nm with some improvements for the 905-nm LILT. Mice receiving two treatments for acute arthritis showed exacerbation of inflammation and articular resorption following therapy with a 660-nm continuous laser (p < 0.05). For chronic inflammation, differences were not noted between LILT treated and untreated injured knee joints (p > 0.05). Among the lasers, the 905 nm tends to show better results for anti-inflammatory effect in acute arthritis, and the 660 nm showed better results in chronic arthritis. In conclusion, LILT wavelength selection depends on the arthritis condition and can demonstrate anti-inflammatory effects for chronic arthritis and reduced resorption area in this murine model.
KeywordsInflammation Lilt Histology Immunohistochemistry Repair
Compliance with ethical standards
Conflict of interest statement
The authors declare that they have no conflict of interest.
Role of funding source
The Fundação de Amparo à Pesquisa do Estado de São Paulo Brazil funding provided a travel grant for J.P.M.I and B.F.T. Funding through the Ontario Ministry of Health and Long-Term Care represents a core operations funding for the Princess Margaret Cancer Centre, not specific to any of the authors.
All procedures were approved by the University Health Network’s Animal Care Committee, complying with regulations of the Canadian Council on Animal Care.
Animals were monitored twice daily for the duration of the study, and a clinical monitoring sheet was used for humane endpoint determination. While humane endpoints were defined, pertaining among others to ambulation, no animal reached an endpoint during the observation period. All animals were euthanized through an intra-cardiac injection of sodium pentobarbital (>120 mg/kg) under deep anesthesia.
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