Low-level laser therapy in IL-1β, COX-2, and PGE2 modulation in partially injured Achilles tendon

Abstract

This study evaluated IL-1β, COX-2, and PGE2 modulation in partially injured Achilles tendons treated with low-level laser therapy (LLLT). Sixty-five male Wistar rats were used. Sixty were submitted to a direct injury on Achilles tendon and then distributed into six groups: LASER 1 (a single LLLT application), LASER 3 (three LLLT applications), and LASER 7 (seven LLLT applications) and Sham 1, 3, and 7 (the same injury but LLLT applications were simulated). The five remaining animals were allocated at control group (no procedure performed). LLLT (780 nm) was applied with 70 mW of mean power and 17.5 J/cm(2) of fluency for 10 s, once a day. The tendons were surgically removed and assessed immunohistochemically for IL-1β, COX-2, and PGE2. In comparisons with control (IL-1β: 100.5 ± 92.5 / COX-2: 180.1 ± 97.1 / PGE2: 187.8 ± 128.8) IL-1β exhibited (mean ± SD) near-normal level (p > 0.05) at LASER 3 (142.0 ± 162.4). COX-2 and PGE2 exhibited near-normal levels (p > 0.05) at LASER 3 (COX-2: 176.9 ± 75.4 / PGE2: 297.2 ± 259.6) and LASER 7 (COX-2: 259.2 ± 190.4 / PGE2: 587.1 ± 409.7). LLLT decreased Achilles tendon's inflammatory process.

Systematic Review of Photobiomodulation Therapy (PBMT) on the Experimental Calcaneal Tendon Injury in Rats

“…Regardless of aforementioned limitations, the included studies investigated several inflammatory mediators, such as pro-inflammatory mediators (interleukin-1 beta (IL-1b), interleukin-6 (IL-6), tumor necrosis factor alpha (TNF-a), cyclooxygenase-2 (COX-2), prostaglandin E2 (PGE2) and transforming growth factor beta (TGF-b)) (10)(11)19,21,(23)(24)27,33,35,39,(47)(48)(50)(51)(52)(53), as well as anti-inflammatory mediator [interleukin-10 (IL-10)] (21,30,48), involved in tendon repair or tendinitis condition. Other inflammatory mediator factors were also studied such as vascular endothelium growth factor (VEGF), metalloproteinase-1 matrix (MMP1), metalloproteinase-2 matrix (MMP-2), metalloproteinase-3 matrix (MMP-3), metalloproteinase-9 matrix (MMP-9), metalloproteinase-13 matrix (MMP13) and induced nitric oxide synthase (i-NOS) (10)(11)(28)(29)(34)(35)37,39,54) that contribute to the understanding of how PBMT can benefited tendon repair or tendinitis condition. In this context, depending on wavelength, dose (Joule), treatment frequency and tendon repair phase, PBMT, either by LLLT or by LED, can modulate levels of gene expression (mRNA), enzymatic activity of metalloproteinases (MMPs) (11,(27)(28)35,39) and collagen synthesis (30,37).…”

“…Currently, in physiotherapeutic clinical practice, mechanical and electromagnetic resources have been widely studied to favor the process of calcaneal tendon repair, among them stands out the photobiomodulation therapy (PBMT) by low-level laser therapy (LLLT) and/or light-emitting diode (LED) (10)(11)(12).…”

“…PBMT by LLLT emits light within the visible (red) or invisible (infrared) electromagnetic spectrum, which differs from ordinary light exhibiting properties such as monochromaticity (wavelength with a narrow spectral band), coherence (phase waves) and collimation (parallel waves) (10)(11)(12). Moreover, light from light-emitting diodes has similar physics properties such as monochromaticity, and lesser coherence and collimation, but promotes similar effects on the tissue compared with LLLT (12,13).…”

Laser Photobiomodulation in the acute inflammatory response of the calcaneal tendon injury in rats exposed to cigarette smoke

“…In addition, an explanation for the decrease in MPO activity levels in PBMG compared to ShG would be the angiogenic effect of laser PBM 28 , which influences the balance of MPO activity, decreases the inflammatory cellular influx 29,30 , and stimulates neovascularization and antibacterial activity, leading to the improvement in the tendon's healing process 21,28,31 . Although these hypotheses have already been demonstrated, they were not evaluated in the present study; laser PBM was applied only once, and the evaluation was immediate (24 hours later), which may have prevented the obtaining of greater anti-inflammatory effects and other effects such as angiogenesis.…”

Efeito da laserterapia de baixa intensidade (904 nm) e do alongamento estático em pacientes com osteoartrite de joelho: ensaio controlado randomizado simples cego

“…Estudos recentes na área básica têm evidenciado o papel da LBI na modulação do processo inflamatório através da redução da IL-1β, IL-6, TNFα, COX-2, PGE2 e na habilidade de inibir a proliferação de células inflamatórias 86,87,88 . A LBI também atua no tecido estimulando a liberação de opióides endógenos como as β-endorfinas e de corticosteroides 89 .…”