ORIGINAL ARTICLE Photobiomodulation therapy in the modulation of inflammatory mediators and bradykinin receptors in an experimental model of acute osteoarthritis Vanessa Lima Cavalcante de Oliveira 1 & José Antonio Silva Jr. 2 & Andrey Jorge Serra 3 & Rodney Capp Pallotta 3 & Evela Aparecida Pereira da Silva 3 & Anna Cristina de Farias Marques 1 & Regiane dos Santos Feliciano 2 & Rodrigo Labat Marcos 3 & Ernesto Cesar Pinto Leal-Junior 1,3 & Paulo de Tarso Camillo de Carvalho 1,3 Received: 4 May 2016 /Accepted: 27 September 2016 # Springer-Verlag London 2016 Abstract The objective of this study was to evaluate the ef- fects of photobiomodulation therapy (PBMT) on inflammato- ry indicators, i.e., inflammatory mediators (TNF-α and CINC- 1), and pain characterized by hyperalgesia and B1 and B2 receptor activation at 6, 24, and 48 h after papain-induced osteoarthritis (OA) in rats. Fifty-four rats were subjected to hyperalgesia evaluations and then divided randomly into three groups—a control group and two groups OA and OA PBMT group by using laser parameters at wavelength (808 nm), out- put power (50 mW), energy per point (4 Joules), power den- sity (1.78 W/cm 2 ), laser beam (0.028 cm 2 ), and energy density (144 J/cm 2 )—the induction of osteoarthritis was then per- formed with 20-μl injections of a 4 % papain solution dis- solved in 10 μl of saline solution, to which 10 μl of cysteine solution (0.03 M). The statistical analysis was performed using two-way ANOVA with Bonferroni’ s post hoc test for comparisons between the 6, 24, and 48 h and team points within each group, and between the control, injury, and PBMT groups, and p < 0.05 was considered to indicate a sig- nificant difference. The hyperalgesia was evaluated at 6, 24, and 48 h after the injury. PBMT at a wavelength of 808 nm and doses of 4 J, administered afterward, promotes increase at the threshold of pressure stimulus at 6, 24, and 48 h after application and promote cytokine attenuation levels (TNF and CINC-1) and bradykinin receptor (B1 and B2) along the experimental period. We conclude that photobiomodulation therapy was able to promote the reduction of proinflammatory cytokines such as TNF-α and CINC-1, to reduce the gene and protein expression of the bradykinin receptor (B1 and B2), as well as increasing the stimulus response threshold of pressure in an experimental model of acute osteoarthritis Keywords Osteoarthritis . Hyperalgesia . Cytokines . Photobiomodulation therapy Introduction Osteoarthritis (OA) is a degenerative joint disease that affects most of the elderly population, causing chronic pain and joint disability. In particular, it is characterized by cartilage break- down that is attributed to an imbalance between the synthetic (anabolic) and resorptive (catabolic) activities of resident chondrocytes and by synovial inflammation that is directly linked to clinical symptoms such as joint swelling, synovitis, and inflammatory pain [1, 2]. The inflammation of the synovial membrane that oc- curs in both the early and late phases of OA is associated with alterations in the adjacent cartilage that are similar to those seen in rheumatoid arthritis. Catabolic and pro- inflammatory mediators such as cytokines, nitric oxide, prostaglandin E2, and neuropeptides are produced by the inflamed synovium and alter the balance of cartilage * Paulo de Tarso Camillo de Carvalho paulo.tarso@uninove.br 1 Postgraduate Program in Rehabilitation Sciences, Universidade Nove de Julho (UNINOVE), Rua Vergueiro 235, São Paulo, SP, Brazil 2 Postgraduate Program in Medicine Universidade Nove de Julho (UNINOVE), São Paulo, SP, Brazil 3 Postgraduate Program in Biophotonics, Universidade Nove de Julho (UNINOVE), São Paulo, SP, Brazil Lasers Med Sci DOI 10.1007/s10103-016-2089-2