Cytokine mRNA expression is decreased in the subplantar muscle of rat paw subjected to carrageenan-induced inflammation after low-level laser therapy

Effect of Photobiomodulation on Salivary Cytokines in Head and Neck Cancer Patients with Oral Mucositis: A Systematic Review

Background: Oral mucositis is a common and distressing side effect of head and neck oncology treatment. Photobiomodulation therapy can be utilized to prevent and treat oral mucositis. Its impact on salivary cytokines has yet to be thoroughly investigated. This is the first systematic review aiming to evaluate the effect of photobiomodulation on salivary cytokines in patients undergoing anticancer treatment. Methods: Numerous data resources, from the Web of Science, Embase, ScienceDirect, PubMed, Cochrane Library, and Scopus were sought. Articles published up until February 2024 were included if they met the following inclusion criteria: clinical trials reporting the effect on salivary cytokines in patients undergoing anticancer therapy. The methodological quality was assessed using several appraisal tools. Results: Four studies were deemed eligible for inclusion. All the studies were conducted in Brazil and used an InGaAlP diode laser with a wavelength of 660 nm. The included studies had a relatively low risk of bias. The head and neck cancer patients' salivary cytokines that were assessed by the studies, along with photobiomodulation therapy, included IL-12p70, TNF-α, IL-6, IL-8, IL-10, CXCL8, and IL-1β. The results varied among the studies. Conclusions: Our results show that photobiomodulation demonstrated positive results for reducing the severity of OM in all the included studies. Among the examined salivary cytokines, IL-6 is the most relevant cytokine for oral mucositis development and severity. A variation in the cytokine levels between the studies was noted due to differences in the type of anticancer treatment and saliva sampling.

Neutrophil response to Porphyromonas gingivalis is modulated by low-level laser application

OBJECTIVES

Neutrophil response is critical in inflammatory regulation and immune response to bacterial infections. During periodontal disease, pathogenic bacteria lead to exaggerated neutrophil responses. We hypothesized that low-level laser application (LLLT), therapeutic strategy for dampening inflammatory processes, will regulate neutrophil activity in response to periodontopathogens.

MATERIALS AND METHODS

The impact of LLLT on neutrophil responses was measured by light delivered at wavelength of 850 nm. The direct effect of LLLT on P. gingivalis A7436 was determined by flow cytometry using LIVE/DEADTM Cell Vitality kit. The phagocytosis of P. gingivalis A7436 by human neutrophils was measured using flow cytometry. Superoxide generation was measured by cytochrome-C-reduction in the presence of N-formyl-L-methionyl-L-leucyl-L-phenylalanine (fMLP; 1 mM). Cytokine release by neutrophils was measured by multiplex immunoassay.

RESULTS

The phagocytosis of P. gingivalis by primary human neutrophils was significantly reduced in response to LLLT (p < 0.05). While LLLT led to increased superoxide production in neutrophils that were not challenged by P. gingivalis, it dampened the increased superoxide and IL-6 release by the neutrophils in response to P. gingivalis. LLLT did not directly affect the viability of P. gingivalis.

CONCLUSION

These results suggested that LLLT can provide therapeutic strategy in periodontal disease, regulating the neutrophil response to P. gingivalis.

Comparison of three different dosages of low-level laser therapy on expression of cell proliferation and inflammatory markers following ovariohysterectomy in rats

The objective of the current study was to evaluate Low-level laser therapy (LLLT) on the healing of incisional wounds following ovariohysterectomy in rats, by means of subjective histopathological and immunohistochemical analysis. A total of 72 female Wistar rats were categorised into four treatment groups (Group I; sacrification 4 hours following only one LLLT application, Group II; sacrification 7 days following only one LLLT application, Group III; sacrification 4 hours after two LLLT applications, and Group IV; sacrification 7 days after two LLLT applications). Each group was further divided into four different doses subgroups (Group Control [C, off mode LLLT application], L1 [1 J/cm2], L3 [3 J/cm2], and L6 [6 J/cm2]), with equal representation in each subgroup. Ovariohysterectomy was employed using two 2-cm-length midline abdominal incisions in the left and right sides of line alba. The Group C was assigned to the left side incision to each rat in the study. After irradiation, the tissue was subjected to histopathological analysis to determine the extent of mononuclear cell infiltration, edoema, and epithelialization. Additionally, immunohistochemical analysis was performed to evaluate the expression of proliferating cell nuclear antigen (pCNA) and inducible nitric oxide synthase (iNOS). Group L1 and L3 significantly decreased mononuclear cell infiltration compared with Group C in all treatment groups (p < 0.05). Group L3 significantly decreased edoema compared with Group C in all groups except for treatment Group I (p < 0.05). Group L2 and L3 significantly increased epithelization in treatment Group IV (p < 0.05). Moreover, Group L2 and L3 significantly increased pCNA in all groups, while L2 and L3 significantly decreased iNOS expression in treatment Group II, III, and IV (p < 0.05). However, no statistical difference was found between subgroups of treatment Group I in iNOS expiration (p > 0.05). The results of the current examination demonstrated that LLLT can modulate mononuclear cell infiltration and edoema, and improve epithelization, as well as increase pCNA expression, whereas decrease iNOS expression during the wound healing process, therefore enhancing wound healing following ovariohysterectomy in rats.

Histomorphometric Analysis of the Healing Capacity of Low-Level Laser on Thermally Induced Tongue Ulcers for Gamma-Irradiated Rats

Objective: This study aimed to assess the efficacy of low-level laser therapy (LLLT) for treating thermal tongue ulcers in gamma-irradiated rats. Background: Postradiotherapeutic trauma may cause cell death, tissue damage, organ dysfunction, and loss of hematological components. Materials and methods: Thermal ulcers were induced on the dorsal surfaces of tongues of gamma-irradiated rats (15 Gy). Rats were divided into three groups, group 1 received no treatment, group 2 was subjected to a single dose of diode laser 807 nm with energy density 4 J/cm2, and group 3 was subjected to the same dose of LLLT but fractionated into three sessions at days 1, 3, and 5 after ulcers induction. Ulcers were assessed clinically for their areas and healing percentage. Specimens were examined for the quality of ulcer closure and expression of IL-1β and TGF-β1. Results: Results revealed significant improvement of ulcer healing clinically and histologically in both treatment groups compared to control. Moreover, IL-1β and TGF-β1 expression in both treatment groups was high at the earlier stage of healing then declined by time to reach a normal level. However, untreated group showed higher expression of IL-1β and TGF-β1 compared to treatment groups. In addition, IL-1β expression decreased by time but still of high level and TGF-β1 expression increased then declined. Conclusions: We concluded that gamma radiation-impaired mucosal healing could be related to the over expression of IL-1β and TGF-β1. LLLT, whether one session or fractionated, could be an effective treatment for postradiotherapeutic ulcers. The healing power of LLLT might be due to modulation of IL-1β and TGF-β1. Clinical Trial Registration number is 25A122.

Efficacy of Low-Level Laser Therapy in a Rabbit Model of Rhinosinusitis

Little is known about alternative treatment options for rhinosinusitis (RS). We aimed to evaluate the efficacy of low-level laser therapy (LLLT) for RS in experimentally induced rabbit models of RS. A total of 18 rabbits were divided into four groups: a negative control group (n = 3), an RS group without treatment (n = 5, positive control group), an RS group with natural recovery (n = 5, natural recovery group), and an RS group with laser irradiation (n = 5, laser-treated group). Computed tomography and histopathological staining were performed for each group. mRNA and protein expression levels of local cytokines (IFN-γ, IL-17, and IL-5) were also measured. Tissue inflammation revealed a significant improvement in the laser-treated group compared with the RS and natural recovery groups (p < 0.01). In addition, sinus opacification in the CT scans and cytokine expression was reduced in the laser-treated group, though without statistical significance. LLLT could be an effective option for the management of RS concerning radiological, histological, and molecular parameters.

Vitex trifolia L. modulates inflammatory mediators via down-regulation of the NF-κB signaling pathway in carrageenan-induced acute inflammation in experimental rats

ETHNOPHARMACOLOGICAL RELEVANCE

Vitex trifolia L. (V. trifolia L.), commonly known as the three-leaved chaste tree, is extensively employed in traditional Chinese medicine (TCM) to treat various conditions associated with inflammation.

AIM OF THE STUDY

The present study aimed to delineate the molecular mechanisms responsible for the anti-inflammatory effect of V. trifolia L. in carrageenan (CA)-induced acute inflammation in experimental rats.

MATERIALS AND METHODS

CA-induced rat paw edema model was adopted to investigate the anti-inflammatory effect of methanolic extract from leaves of V. trifolia L. (VTME) in vivo. Leukocyte infiltration into the site of inflammation was determined by histopathological analysis. Further, the effect of VTME on CA-induced local and systemic levels of specific cytokines was quantified by enzyme-linked immunosorbent assay (ELISA). Moreover, its impact on the nuclear translocation of nuclear factor Kappa B (NF-κB) was analyzed by employing the western blotting technique.

RESULTS

VTME at the doses of 100 mg/kg and 200 mg/kg significantly inhibited the paw edema induced by CA (p < 0.05) and effectively reduced the inflammatory leukocyte infiltration. Further, VTME markedly inhibited the CA-induced levels of Interleukin (IL)-1β, IL-6, tumor necrosis factor (TNF)-α in tissue, and that of cytokine-induced neutrophil chemoattractant (CINC)-2/C-X-C motif chemokine (CXCL)3 and CINC-3/CXCL2 in tissue as well as in serum. On the other hand, VTME significantly upregulated the tissue concentration of anti-inflammatory cytokine IL-10. Moreover, VTME significantly attenuated the CA-induced IκBα degradation and nuclear translocation of NF-κB p65.

CONCLUSIONS

Our results demonstrate the potent anti-inflammatory effect of V. trifolia L. in vivo, providing insight into its molecular mechanism, which is mediated through down-regulation of NF-κB signal transduction.

Analysis of pain relief and functional recovery in patients with rotator cuff tendinopathy through therapeutic ultrasound and photobiomodulation therapy: a comparative study

This study aimed to compare shoulder tendinopathy treatment with therapeutic ultrasound combined with LED photobiomodulation therapy using LED-infrared (850 nm) or LED-red (640 nm). The study assessed 75 patients, aged 45 to 70 years, distributed into five experimental groups (15 patients each): therapeutic ultrasound (US), infrared light irradiation (IR), visible red light irradiation (VR), infrared light and ultrasound combined (IR-US), and red light in conjunction with ultrasound (VR-US). The ultrasound parameters are 1 MHz, 0.5 W/cm² (SATA), and 100 Hz repetition rate, applied for 4 min each session. LED irradiation protocols were as follows: 3 points, 7.5 J per point, IR-LED 750 mW, 10 s, VR-LED 250 mW, 30 s. LED irradiation is followed by ultrasound in the combined therapies. The efficiency of the five therapies was evaluated assessing 12 parameters: quality of life (Health Assessment Questionnaire, HAQ), pain intensity (Visual Analog Scale, VAS), articular amplitude of shoulder movement (flexion, extension, abduction, adduction, medial rotation, lateral rotation), muscle strength (abduction, lateral rotation), and electromyography (lateral rotation, abduction). Treatments comprised 12 sessions for 4 weeks. Intra-group analysis showed that the five therapies significantly improved the recovery of all parameters after treatment. Regarding the comparison of irradiated therapies and ultrasound, statistical analysis showed that IR-US was a better treatment than US for all 12 parameters. IR treatment exceeded US on 9 items, whereas that VR and VR-US therapies exceeded US in 7 and 10 parameters, respectively (p < 0.05). Because of that, IR-US shows to be the best treatment for rotator cuff tendinopathy. In conclusion, improvements in quality of life, pain intensity relief, shoulder amplitude motion, and muscle strength force obtained with ultrasound therapy are enhanced by adding infrared LED irradiation to ultrasound for patients suffering from rotator cuff tendinopathy. This study was registered with the Brazilian Registry of Clinical Trials (ReBEC) under Universal Trial Number (UTN) U1111-1219-3594 (2018/22/08).

Photobiomodulation therapy's effects on cardiac fibrosis activation after experimental myocardial infarction

INTRODUCTION

Ischemic heart disease is the leading cause of death worldwide, and interventions to reduce myocardial infarction (MI) complications are widely researched. Photobiomodulation therapy (PBMT) has altered multiple biological processes in tissues and organs, including the heart.

OBJECTIVES

This study aimed to assess the temporal effects of PBMT on cardiac fibrosis activation after MI in rats. In this proof-of-concept study, we monitored the change in expression patterns over time of genes and microRNAs (miRNAs) involved in the formation of cardiac fibrosis post-MI submitted to PBMT.

MATERIALS AND METHODS

Experimental MI was induced, and PBMT was applied shortly after coronary artery ligation (laser light of wavelength 660 nm, 15 mW of power, energy density 22.5 J/cm² , 60 seconds of application, irradiated area 0.785 cm² , fluence 1.1 J/cm² ). Ventricular septal samples were collected at 30 minutes, 3, 6, 24 hours, and 3 days post-MI to determine temporal PBMT's effects on messenger RNA (mRNA) expression associated with cardiac fibrosis activation and miRNAs expression.

RESULTS

PBMT, when applied after ischemia, reversed the changes in mRNA expression of myocardial extracellular matrix genes induced by MI. Surprisingly, PBMT modified cardiac miRNAs expression related to fibrosis replacement in the myocardium. Expression correlations between myocardial mRNAs were assessed. The correlation coefficient between miRNAs and target mRNAs was also determined. A positive correlation was detected among miR-21 and transforming growth factor beta-1 mRNA. The miR-29a expression negatively correlated to Col1a1, Col3a1, and MMP-2 mRNA expressions. In addition, we observed that miR-133 and Col1a1 mRNA were negatively correlated.

CONCLUSION

The results suggest that PBMT, through the modulation of gene transcription and miRNA expressions, can interfere in cardiac fibrosis activation after MI, mainly reversing the signaling pathway of profibrotic genes.

Chronological Gene Expression of Human Gingival Fibroblasts with Low Reactive Level Laser (LLL) Irradiation

Though previously studies have reported that Low reactive Level Laser Therapy (LLLT) promotes wound healing, molecular level evidence was uncleared. The purpose of this study is to examine the temporal molecular processes of human immortalized gingival fibroblasts (HGF) by LLLT by the comprehensive analysis of gene expression. HGF was seeded, cultured for 24 h, and then irradiated with a Nd: YAG laser at 0.5 W for 30 s. After that, gene differential expression analysis and functional analysis were performed with DNA microarray at 1, 3, 6 and 12 h after the irradiation. The number of genes with up- and downregulated differentially expression genes (DEGs) compared to the nonirradiated group was large at 6 and 12 h after the irradiation. From the functional analysis results of DEGs, Biological Process (BP) based Gene Ontology (GO), BP ‘the defense response’ is considered to be an important process with DAVID. Additionally, the results of PPI analysis of DEGs involved in the defense response with STRING, we found that the upregulated DEGs such as CXCL8 and NFKB1, and the downregulated DEGs such as NFKBIA and STAT1 were correlated with multiple genes. We estimate that these genes are key genes on the defense response after LLLT.

Photobiomodulation exerts anti-inflammatory effects on the vascular and cellular phases of experimental inflammatory models

Photobiomodulation therapy (PBMT) is a non-thermal therapeutic procedure widely used in clinical practice. It is considered an effective modality of treatment for the control of various inflammatory conditions with fewer adverse effects as compared to conventional therapy. However, despite the clinical effects, the mechanisms of action and dosimetric parameters of PBMT are not fully understood. This study was performed to describe the effects of two different doses of PBMT on experimental models of inflammation. Male Swiss mice were administered with 0.9% of saline or phlogistic agents (carrageenan, dextran, serotonin, histamine, or bradykinin) by intra-plantar injection and were treated with PBMT at a dose of 1 or 5 J/cm²; right after, the variation of the paw volume was made, and histopathological analysis and myeloperoxidase assay of the carrageenan-induced edematous paw tissues were performed. The action of PBMT on carrageenan-induced vascular permeability was further evaluated. Our results showed that PBMT (1 J/cm²) led to an improvement in paw edema induced by the phlogistic agents and further reduced the histological scores. Inhibition of neutrophil migration was observed following the administration of 1 and 5 J/cm² of PBMT. However, only 1 J/cm² of PBMT showed beneficial effects on carrageenan-induced edema. Laser at a dose of 1 J/cm² showed cellular and vascular effects since it was able to reverse all the inflammatory parameters, and laser at a dose of 5 J/cm² probably has only cellular effects in the presence of acute inflammation.

Photobiomodulation: A review of the molecular evidence for low level light therapy

Light energy is harnessed for therapeutic use in a number of ways, most recently by way of photobiomodulation (PBM). This phenomenon is a cascade of physiological events induced by the nonthermal exposure of tissue to light at the near infrared end of the visible spectrum. Therapeutic PBM has become a highly commercialized interest, marketed for everything from facial rejuvenation to fat loss, and diode-based devices are popular in both the clinic setting and for use at home. The lack of regulatory standards makes it difficult to draw clear conclusions about efficacy and safety but it is crucial that we understand the theoretical basis for PBM, so that we can engage in an honest dialogue with our patients and design better clinical studies to put claims of efficacy to the test. This article presents a summary of the science of PBM and examines the differences between laser light, on which much of the preclinical evidence is based and light from diodes, which are typically used in a clinical setting.

The effect of red-to-near-infrared (R/NIR) irradiation on inflammatory processes

Introduction: Near-infrared (NIR) and red-to-near-infrared (R/NIR) radiation are increasingly applied for therapeutic use. R/NIR-employing therapies aim to stimulate healing, prevent tissue necrosis, increase mitochondrial function, and improve blood flow and tissue oxygenation. The wide range of applications of this radiation raises questions concerning the effects of R/NIR on the immune system. Methods: In this review, we discuss the potential effects of exposure to R/NIR light on immune cells in the context of physical parameters of light. Discussion: The effects that R/NIR may induce in immune cells typically involve the production of reactive oxygen species (ROS), nitrogen oxide (NO), or interleukins. Production of ROS after exposure to R/NIR can either be inhibited or to some extent increased, which suggests that detailed conditions of experiments, such as the spectrum of radiation, irradiance, exposure time, determine the outcome of the treatment. However, a wide range of immune cell studies have demonstrated that exposure to R/NIR most often has an anti-inflammatory effect. Finally, photobiomodulation molecular mechanism with particular attention to the role of interfacial water structure changes for cell physiology and regulation of the inflammatory process was described. Conclusions: Optimization of light parameters allows R/NIR to act as an anti-inflammatory agent in a wide range of medical applications.

Intravenous Laser Wavelength Irradiation Effect on Interleukins: IL-1α, IL-1β, IL6 in Diabetic Rats

Background and aims

The main purpose of this investigation in Low-Level Laser Therapy (LLLT) on diabetic rats is laser wavelength effect on interleukins: IL-1α, IL-1β, IL6.

Materials Subjects and Methods

At first, diabetes was induced in Wistar rats by streptozotocin (STZ) injection. Then, by intravenous laser therapy, the rats were irradiated by four continuous wave lasers: IR (λ = 808 nm), Red (λ = 638 nm), Green (λ = 532 nm) and Blue (λ= 450 nm) to compare the related laser wavelength effect on different interleukins. The inflammatory parameters were measured 2,6 and 24 hours after laser therapy from blood samples and plotted for different laser wavelengths.

Results

The results show a decrease in all the above parameters by different laser irradiation in comparison to non-radiated diabetic control ones. More importantly with constant laser energy as the laser wavelength decreases, it affects more efficiently on lowering the above parameters.

Conclusions

we can conclude from our data on diabetic rats that in intravenous LLLT, with constant laser energy, shorter wavelengths like Blue (λ= 450 nm) is more effective than longer wavelengths such as Red (λ = 638 nm) and IR (λ = 808 nm) lasers to lower the level of interleukins toward non-diabetic ones.

Low-Level Laser Application in the Early Myocardial Infarction Stage Has No Beneficial Role in Heart Failure

Low-level laser therapy (LLLT) has been targeted as a promising approach that can mitigate post-infarction cardiac remodeling. There is some interesting evidence showing that the beneficial role of the LLLT could persist long-term even after the end of the application, but it remains to be systematically evaluated. Therefore, the present study aimed to test the hypothesis that LLLT beneficial effects in the early post-infarction cardiac remodeling could remain in overt heart failure even with the disruption of irradiations. Female Wistar rats were subjected to the coronary occlusion to induce myocardial infarction or Sham operation. A single LLLT application was carried out after 60 s and 3 days post-coronary occlusion, respectively. Echocardiography was performed 3 days and at the end of the experiment (5 weeks) to evaluate cardiac function. After the last echocardiographic examination, LV hemodynamic evaluation was performed at baseline and on sudden afterload increases. Compared with the Sham group, infarcted rats showed increased systolic and diastolic internal diameter as well as a depressed shortening fraction of LV. The only benefit of the LLLT was a higher shortening fraction after 3 days of infarction. However, treated-LLLT rats show a lower shortening fraction in the 5th week of study when compared with Sham and non-irradiated rats. A worsening of cardiac function was confirmed in the hemodynamic analysis as evidenced by the higher LV end-diastolic pressure and lower +dP/dt and −dP/dt with five weeks of study. Cardiac functional reserve was also impaired by infarction as evidenced by an attenuated response of stroke work index and cardiac output to a sudden afterload stress, without LLLT repercussions. No significant differences were found in the myocardial expression of Akt₁/VEGF pathway. Collectively, these findings illustrate that LLLT improves LV systolic function in the early post-infarction cardiac remodeling. However, this beneficial effect may be dependent on the maintenance of phototherapy. Long-term studies with LLLT application are needed to establish whether these effects ultimately translate into improved cardiac remodeling.

Photobiomodulation therapy in the modulation of inflammatory mediators and bradykinin receptors in an experimental model of acute osteoarthritis

The objective of this study was to evaluate the effects of photobiomodulation therapy (PBMT) on inflammatory 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), output power (50 mW), energy per point (4 Joules), power density (1.78 W/cm²), laser beam (0.028 cm²), and energy density (144 J/cm²)-the induction of osteoarthritis was then performed with 20-μl injections of a 4 % papain solution dissolved 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 significant 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.

Photobiomodulation with 660-nm and 780-nm laser on activated J774 macrophage-like cells: Effect on M1 inflammatory markers

M1 profile macrophages exert a major influence on initial tissue repair process. Few days after the occurrence of injury, macrophages in the injured region exhibit a M2 profile, attenuate the effects of the M1 population, and stimulate the reconstruction of the damaged tissue. The different effects of macrophages in the healing process suggest that these cells could be the target of therapeutic interventions. Photobiomodulation has been used to accelerate tissue repair, but little is known regarding its effect on macrophages. In the present study, J774 macrophages were activated to simulate the M1 profile and irradiated with two different sets of laser parameters (780 nm, 70 mW, 2.6J/cm(2), 1.5s and 660 nm, 15 mW, 7.5 J/cm(2), 20s). IL-6, TNF-α, iNOS and COX-2 gene and protein expression were analyzed by RT-qPCR and ELISA. Both lasers were able to reduce TNF-α and iNOS expression, and TNF-α and COX-2 production, although the parameters used for 780 nm laser provided an additional decrease. 660 nm laser parameters resulted in an up-regulation of IL-6 expression and production. These findings imply a distinct, time-dependent modulation by the two different sets of laser parameters, suggesting that the best modulation may involve more than one combination of parameters.

Low Reactive Level Laser Therapy for Mesenchymal Stromal Cells Therapies

Low reactive level laser therapy (LLLT) is mainly focused on the activation of intracellular or extracellular chromophore and the initiation of cellular signaling by using low power lasers. Over the past forty years, it was realized that the laser therapy had the potential to improve wound healing and reduce pain and inflammation. In recent years, the term LLLT has become widely recognized in the field of regenerative medicine. In this review, we will describe the mechanisms of action of LLLT at a cellular level and introduce the application to mesenchymal stem cells and mesenchymal stromal cells (MSCs) therapies. Finally, our recent research results that LLLT enhanced the MSCs differentiation to osteoblast will also be described.

Low-level laser therapy on skeletal muscle inflammation: evaluation of irradiation parameters

We evaluated the effect of different irradiation parameters in low-level laser therapy (LLLT) for treating inflammation induced in the gastrocnemius muscle of rats through cytokines concentration in systemic blood and analysis of muscle tissue. We used continuous (830 and 980 nm) and pulsed illuminations (830 nm). Animals were divided into five groups per wavelength (10, 20, 30, 40, and 50 mW), and a control group. LLLT was applied during 5 days with a constant irradiation time and area. TNF-α, IL-1β, IL-2, and IL-6 cytokines were quantified by ELISA. Inflammatory cells were counted using microscopy. Identical methodology was used with pulsed illumination. Average power (40 mW) and duty cycle were kept constant (80%) at five frequencies (5, 25, 50, 100, and 200 Hz). For continuous irradiation, treatment effects occurred for all doses, with a reduction of TNF-α, IL-1β, and IL-6 cytokines and inflammatory cells. Continuous irradiation at 830 nm was more effective, a result explained by the action spectrum of cytochrome c oxidase (CCO). Best results were obtained for 40 mW, with data suggesting a biphasic dose response. Pulsed wave irradiation was only effective for higher frequencies, a result that might be related to the rate constants of the CCO internal electron transfer process.

Therapeutic effect of irradiation of magnetic infrared laser on osteoarthritis rat model

Osteoarthritis (OA) is a degenerative joint disease caused by articular cartilage loss. Many complementary and alternative medicines for OA have been reported so far, but the effectiveness is controversial. Previously, we have shown anti-inflammatory effects of low level laser therapy with static magnetic field, magnetic infrared laser (MIL), in various animal models. Therefore, the beneficial effects were examined in OA rat model. Rats were divided by six groups; no treatment controls of sham and OA model, three MIL treatment groups of OA model at 6.65, 2.66 and 1.33 J cm(-2), and Diclofenac group of OA model with 2 mg kg(-1) diclofenac sodium. The OA control exhibited typical symptoms of OA, but 4-week MIL treatment improved the functional movement of knee joint with reduced edematous changes. In addition, cartilage GAGs were detected more in all MIL treatment groups than OA control. It suggests that 4-week MIL irradiation has dose-dependent anti-inflammatory and chondroprotective effects on OA. Histopathological analyses revealed that MIL treatment inhibits the cartilage degradation and enhances chondrocyte proliferation. The fact that MIL has an additional potential for the cartilage formation and no adverse effects can be regarded as great advantages for OA treatment. These suggest that MIL can be useful for OA treatment.

The influence of low-level laser therapy on parameters of oxidative stress and DNA damage on muscle and plasma in rats with heart failure

In heart failure (HF), there is an imbalance between the production of reactive oxygen species and the synthesis of antioxidant enzymes, causing damage to the cardiovascular function and increased susceptibility to DNA damage. The aim of this study was to evaluate the influence of low-level laser therapy (LLLT) on parameters of oxidative stress and DNA damage in skeletal muscle and plasma of rats with HF. Wistar rats were allocated into six groups: "placebo" HF rats (P-HF, n = 9), "placebo" Sham rats (P-sham, n = 8), HF rats at a dose 3 J/cm(2) of LLLT (3 J/cm(2)-HF, n = 8), sham rats at a dose 3 J/cm(2) of LLLT (3 J/cm(2)-sham, n = 8), HF rats at a dose 21 J/cm(2) of LLLT (21 J/cm(2)-HF, n = 8) and sham rats at a dose 21 J/cm(2) of LLLT (21 J/cm(2)-sham, n = 8). Animals were submitted to a LLLT protocol for 10 days at the right gastrocnemius muscle. Comparison between groups showed a significant reduction in superoxide dismutase (SOD) activity in the 3 J/cm(2)-HF group (p = 0.03) and the 21 J/cm(2)-HF group (p = 0.01) compared to the P-HF group. 2',7'-Dihydrodichlorofluorescein (DCFH) oxidation levels showed a decrease when comparing 3 J/cm(2)-sham to P-sham (p = 0.02). The DNA damage index had a significant increase either in 21 J/cm(2)-HF or 21 J/cm(2)-sham in comparison to P-HF (p = 0.004) and P-sham (p = 0.001) and to 3 J/cm(2)-HF (p = 0.007) and 3 J/cm(2)-sham (p = 0.037), respectively. Based on this, laser therapy appears to reduce SOD activity and DCFH oxidation levels, changing the oxidative balance in the skeletal muscle of HF rats. Otherwise, high doses of LLLT seem to increase DNA damage.

Low level laser therapy on experimental myopathy

PURPOSE

The aim of the present work was to study the effect of Helium-Neon (HeNe) and Gallium Arsenide (GaAs) laser upon nitric oxide (NO) plasma levels, an inflammatory biomarker associated with oxidative stress, in rats with experimental myopathy. These were evaluated through histological assessment.

MATERIALS AND METHODS

The groups studied were: (A) control (intact rats that received LLLT sham exposures), (B) rats with myopathy and sacrificed at 24 h later, (C) rats with myopathy and sacrificed 8 days later, (D) rats with myopathy and treated with HeNe laser, (E) rats with myopathy and treated with GaAs laser, (F) intact rats treated with HeNe laser and (G) intact rats treated with GaAs laser. Myopathy was induced by injecting 50μl of 1% carrageenan λ (type IV) in the left gastrocnemius muscle. Low Level Laser Therapy (LLLT) was applied with 9.5 J.cm(-2) daily for 10 consecutive days with each laser. The determination of the NO was made by spectrophotometry. The muscles were stained with Hematoxylin-Eosin and examined by optic microscopy. Quantitative variables were statistically analyzed by the Fisher test, and categorical by applying Pearson's Chi Squared test at p <0.05 for all cases.

RESULTS

In groups B and C, NO was significantly increased compared to groups A, D, E, F and G (p<0.05). In group C, the percentage of area with inflammatory infiltration was significantly increased compared to the other groups (p<0.001).

CONCLUSIONS

LLLT decreased plasma levels of NO in rats with experimental myopathies and significant muscle recovery.

Evaluation of corticosterone and IL-1β, IL-6, IL-10 and TNF-α expression after 670-nm laser photobiomodulation in rats

The literature has shown that low-level laser therapy accelerates the repair of cutaneous wounds. However, there is a scarcity of scientific studies that characterise the possible systemic interference of laser photobiomodulation. The aim of this research was to quantitatively evaluate blood corticosterone levels and tissue cytokine expression in cutaneous wounds of rats treated with low-level laser therapy (semiconductor diode AsGaAl, continuous emission, 9 mW, 670 nm, 0.031 W/cm(2), beam with an output area of 0.28 cm(2)) and normal controls. A total of 36 male Wistar rats were used and randomly divided into two groups of 18 rats each. A standardised circular 6-mm-diameter wound was made in the dorsal skin region of each rat, and they were euthanised at 1, 6 and 12 h after cutaneous surgery. The blood was collected, and portions of cutaneous tissue and subcutaneous muscle were removed and cryopreserved. Corticosterone levels in the blood were measured by a radioimmunoassay technique; histological sections were submitted to the ELISA technique for analysis of tissue cytokine expression levels. At 6 h after surgery, a significant increase in corticosterone and a significant reduction in the levels of IL-1β and IL-6 in tissues of irradiated wounds were observed when compared to controls (p < 0.05). The levels of TNF-α and IL-10 expression were not significantly different between the groups at different time intervals. Thus, this study strongly suggests a systemic and local biomodulation of low-level laser therapy as indicated by the blood levels of corticosterone and the tissue expression of IL-1β and IL-6, respectively.

Potentiated anti-inflammatory effect of combined 780 nm and 660 nm low level laser therapy on the experimental laryngitis

Reflux laryngitis is a common clinic complication of nasogastric intubation (NSGI). Since there is no report concerning the effects of low level laser therapy (LLLT) on reflux laryngitis, this study aimed to analyze the protective effect of single and combined therapies with low level laser at the doses of 2.1J and 2.1+1.2 J with a total irradiation time of 30s and 30+30 s, respectively, on a model of neurogenic reflux laryngitis. NSGI was performed in Wistar rats, assigned into groups: NGI (no treatment), NLT17.5 (single therapy), and NLT17.5/10.0 (combined therapy, applied sequentially). Additional non-intubated and non-irradiated rats were use as controls (CTR). Myeloperoxidase (MPO) activity was assessed by colorimetric method after the intubation period (on days 1, 3, 5, and 7), whereas paraffin-embedded laryngeal specimens were used to carry out histopathological analysis of the inflammatory response, granulation tissue, and collagen deposition 7 days after NSGI. Significant reduction in MPO activity (p<0.05) and in the severity of the inflammatory response (p<0.05), and improvement in the granulation tissue (p<0.05) was observed in NLT17.5/10.0 group. Mast cells count was significantly decreased in NGI and NLT17.5 groups (p<0.001), whereas no difference was observed between NLT17.5/10.0 and CTR groups (p>0.05). NLT17.5/10.0 group also showed better collagenization pattern, in comparison to NGI and NLT17.5 groups. This study suggests that the combined therapy successfully modulated the inflammatory response and collagenization in experimental model of NSGI-induced neurogenic laryngitis.

Low-level laser therapy alleviates neuropathic pain and promotes function recovery in rats with chronic constriction injury: possible involvements in hypoxia-inducible factor 1α (HIF-1α)

Nerve inflammation plays an important role in the development and progression of neuropathic pain after chronic constrictive injury (CCI). Recent studies have indicated that hypoxia-inducible factor 1α (HIF-1α) is crucial in inflammation. Low-level laser therapy has been used in treating musculoskeletal pain, but rare data directly support its use for neuropathic pain. We investigated the effects of low-level laser on the accumulation of HIF-1α, tumor necrosis factor-α (TNF-α), and interleukin-1β (IL-1β) in controlling neuropathic pain, as well as on the activation of vascular endothelial growth factor (VEGF) and nerve growth factor (NGF) in promoting functional recovery in a rat CCI model. CCI was induced by placing four loose ligatures around the sciatic nerve of rats. Treatments of low-level laser (660 nm, 9 J/cm(2)) or sham irradiation (0 J/cm(2)) were performed at the CCI sites for 7 consecutive days. The effects of laser in animals with CCI were determined by measuring the mechanical paw withdrawal threshold, as well as the sciatic, tibial, and peroneal function indices. Histopathological and immunoassay analyses were also performed. Low-level laser therapy significantly improved paw withdrawal threshold and the sciatic, tibial, and peroneal functional indices after CCI. The therapy also significantly reduced the overexpressions of HIF-1α, TNF-α, and IL-1β, and increased the amounts of VEGF, NGF, and S100 proteins. In conclusion, a low-level laser could modulate HIF-1α activity. Moreover, it may also be used as a novel and clinically applicable therapeutic approach for the improvement of tissue hypoxia/ischemia and inflammation in nerve entrapment neuropathy, as well as for the promotion of nerve regeneration. These findings might lead to a sufficient morphological and functional recovery of the peripheral nerve.

Prevention and treatment of mice paw edema by near-infrared low-level laser therapy on lymph nodes

Low-level laser therapy (LLLT) has been demonstrated to modulate inflammatory processes and immunological responses. The aim of this work was to investigate the hypothesis that near infrared LLLT (830 nm) over lymph nodes may reduce paw edema and contribute to the modulation of inflammation. The edema was induced by carrageenan inoculation (CGN) into the plantar surface of 100 male mice left hind paw. Animals were divided into five groups: CGN (control), no treatment; Diclo, sodium diclofenac; Paw, LLLT on the paw; Ly, LLLT on the inguinal lymph nodes; and Paw+Ly, LLLT in both paw and lymph nodes, and subdivided according to moment of irradiation: A-1 h and 2 h before CGN, B-1 h and immediately before CGN, C-1 and 2 h after CGN, and D-3.5 and 4.5 h after CGN. The parameters used were: energy=1 J, fluence=35 J/cm(2), power=100 mW during 10 s. Paw volume was measured before and 1 to 6 h after CGN, and myeloperoxidase (MPO) activity was analyzed. Edema prevention was obtained by the irradiation of Paw+Ly at moment A and at Ly at moment B, inhibition of edema formation was achieved by either Paw or Ly at moment C, and edema treatment was obtained by Paw or Ly at moment D (p<0.05). MPO activity was significantly reduced on Paw at moment A, Paw and Ly on C, and in all irradiated groups on B and D. Our results suggest that LLLT was able to produce both anti-inflammatory and pro-inflammatory effects depending on to the site and moment of irradiation.

Analgesic effect of a low-level laser therapy (830 nm) in early orthodontic treatment

The aim of this study was to evaluate the pain sensation that orthodontic patients experience when elastic separators are placed between molars and premolars and to determine the degree of analgesic efficacy of low-level laser therapy (LLLT) compared to a placebo treatment. The study was conducted with 20 volunteers who were fitted with elastic separators between the maxillary molars and premolars. One quadrant was randomly chosen to be irradiated with an 830-nm laser, 100 mW, beam diameter of 7 mm, 250 mW/cm(2) applied for 20 s per point (5 J/cm(2)). Three points were irradiated in the buccal face and three were irradiated in the palate. The same procedure was applied in the contralateral quadrant with a placebo light. A visual analogue scale was used to assess pain 5 min, 6 h, 24 h, 48 h, and 72 h after placement of the separators. Maximum pain occurred 6-24 h after placement of the elastic separators. Pain intensity was significantly lower in the laser-treated quadrant (mean, 7.7 mm) than in the placebo-treated quadrant (mean, 14.14 mm; p = 0.0001). LLLT at these parameters can reduce pain in patients following placement of orthodontic rubber separators.

Gene expression in skin, muscle, and dorsal root ganglion after plantar incision in the rat

BACKGROUND

Treating postoperative pain remains a significant challenge for perioperative medicine. Recent studies have shown that nerve growth factor is up-regulated and contributes to incisional pain. To date, few studies have examined expression of other neurotrophin-related mediators that may contribute to the development and/or maintenance of incisional pain.

METHODS

Male Sprague-Dawley rats underwent a plantar incision, and pain behaviors were examined (n = 6). In a separate group of rats, expression of neurotrophic factors were studied. At various times after incision (n = 4) or sham surgery (n = 4), the skin, muscle, and dorsal root ganglia were harvested and total RNA isolated. Real-time reverse transcription polymerase chain reaction was performed and the fold change in gene expression was analyzed using significance analysis of microarrays.

RESULTS

Several genes were changed (P < 0.05) as early as 1 h after incision. Expression of artemin and nerve growth factor were increased in both incised skin and muscle. Brain-derived neurotrophic factor, neurotrophin-3, and neurotrophin-5 were all down-regulated in the skin but up-regulated in the muscle 48 h after incision. Few genes changed in the dorsal root ganglion. Most changes in expression occurred in the first 48 h after incision, a timeframe when pain behavior was the greatest.

CONCLUSION

Surgical incision is associated with pain-related gene expression changes in skin, muscle, and, to a lesser extent, dorsal root ganglion. The gene expression profile provides clues as to mediators that are involved in peripheral sensitization and pain transmission after surgical incision and also suggest mechanisms for resolution of postoperative pain when more persistent pain syndromes like neuropathic pain continue.

Amelioration of experimental autoimmune encephalomyelitis in C57BL/6 mice by photobiomodulation induced by 670 nm light

BACKGROUND

The approved immunomodulatory agents for the treatment of multiple sclerosis (MS) are only partially effective. It is thought that the combination of immunomodulatory and neuroprotective strategies is necessary to prevent or reverse disease progression. Irradiation with far red/near infrared light, termed photobiomodulation, is a therapeutic approach for inflammatory and neurodegenerative diseases. Data suggests that near-infrared light functions through neuroprotective and anti-inflammatory mechanisms. We sought to investigate the clinical effect of photobiomodulation in the Experimental Autoimmune Encephalomyelitis (EAE) model of multiple sclerosis.

METHODOLOGY/PRINCIPAL FINDINGS

The clinical effect of photobiomodulation induced by 670 nm light was investigated in the C57BL/6 mouse model of EAE. Disease was induced with myelin oligodendrocyte glycoprotein (MOG) according to standard laboratory protocol. Mice received 670 nm light or no light treatment (sham) administered as suppression and treatment protocols. 670 nm light reduced disease severity with both protocols compared to sham treated mice. Disease amelioration was associated with down-regulation of proinflammatory cytokines (interferon-γ, tumor necrosis factor-α) and up-regulation of anti-inflammatory cytokines (IL-4, IL-10) in vitro and in vivo.

CONCLUSION/SIGNIFICANCE

These studies document the therapeutic potential of photobiomodulation with 670 nm light in the EAE model, in part through modulation of the immune response.

Ação da terapia com laser de baixa potência nas fases iniciais do reparo tecidual: princípios básicos

O objetivo do estudo foi revisar a literatura a respeito da terapia com laser de baixa potência e sua relação com as fases iniciais de reparo. Foram analisados 22 artigos, observando-se a utilização de diferentes doses e comprimentos de ondas (632,8 a 904 nm). Nos estudos in vitro, foram utilizadas doses entre 2,2 e 16 J/cm². A dose de 5 J/cm² tem sido apontada como responsável por mudanças significativas in vitro; porém, a dose de 16 J/cm² promove efeito inibitório sobre o crescimento celular em culturas. Em estudos in vivo, envolvendo animais, foram utilizadas doses entre 0,04 a 21 J/cm². Para estudos em humanos, foram utilizadas doses entre 1,8 a 16 J/cm². Conclui-se que a terapia com laser de baixa potência exerce efeitos anti-inflamatórios importantes nos processos iniciais da cicatrização: redução de mediadores químicos, de citocinas, do edema, diminuição da migração de células inflamatórias e incremento de fatores de crescimento, contribuindo diretamente para o processo de reabilitação tecidual. Porém, a falta de padronização dificulta a escolha de parâmetros ideais.

Low-level laser therapy, at 830 nm, for pain reduction in experimental model of rats with sciatica

Chronic pain, resulting from nerve compression, is a common clinical presentation. One means of conservative treatment is low-level laser therapy, although controversial. The aim of this study was to evaluate the effects of two doses of low-level laser, at 830 nm, on pain reduction in animals subjected to sciatica. Eighteen rats were used, divided into three groups: GS (n=6), sciatica and simulated treatment; G4J (n=6), sciatica and treatment with 4 J/cm²; and G8J (n=6), sciatica and irradiation with 8 J/cm². The right sciatic nerve was exposed and compressed using catgut thread. Five days of treatment were started on the third postoperative day. Pain was assessed by means of the paw elevation time during gait: before sciatica, before and after the first and second therapies, and the end of the fifth therapy. Low-level laser was effective in reducing the painful condition.

Single session to infrared low level diode laser on TNF-alpha and IL-6 cytokines release by mononuclear spleen cells in mice: a pilot study

BACKGROUND AND OBJECTIVE

The results of low-level infrared laser (LLL) systemic action on inflammatory modulation process, specifically diminishing pro-inflammatory and producing anti-inflammatory cytokines are extremely controversial in the literature. More studies are necessary to clarify the biomodulation process. The main objective was to investigate the effect of a single session of an AsGaAl laser on spleen cells interleukin-6 (IL-6) and tumor necrosis factor - alpha (TNF-alpha) release, in vivo, in mice.

STUDY DESIGN/MATERIALS AND METHODS

In a pilot study, 18 isogenic mice were distributed in three groups: control (no surgical procedure, n = 6), sham (surgical procedure with three standard cutaneous incisions, followed by abdominal muscle incision followed by suture, n = 6) and LLL (same procedure followed by a single LLL exposure 12 hours after the procedure, n = 6). The animals in the LLL group received a single infrared continuous laser session (780 nm wavelength, power of 20 mW, energy density of 10 J/cm(2)) on three points (20 seconds per point), and final energy of 0.4 J. All animals of the sham and LLL groups were sacrificed 36 hours after surgical procedure; the spleen mononuclear cells were isolated and cultivated for 48 hours. The IL-6 and TNF-alpha were measured by the ELISA method.

RESULTS

IL-6 and TNF-alpha concentrations released by the mononuclear cells showed significant differences between the control and sham group (P < 0.07). However, there were no differences between the control and LLL group and between the sham and LLL groups (P > 0.07).

CONCLUSION

The single session of infrared LLL showed a tendency of decreasing the IL-6 and TNF-alpha release by mononuclear spleen cells in mice after application, although there was not a significant difference between the sham and LLL group. Conclusions regarding effectiveness of a single session procedure cannot be made due to the low statistical power of this pilot study.

Anti-inflammatory effects of low-level light emitting diode therapy on Achilles tendinitis in rats

BACKGROUND AND OBJECTIVES

The present study investigated the effects of low-level light emitting diode (LED) therapy (880 +/- 10 nm) on inflammatory process in a experimental model of Achilles tendinitis induced by collagenase.

STUDY DESIGN/MATERIALS AND METHODS

Fifty-six male Wistar were separated into seven groups (n = 8), three groups in the experimental period of 7 days and four groups in the experimental period of 14 days, the control group (CONT), tendinitis group (TEND), LED therapy group (LEDT) for both experimental periods, and LED therapy group 7th to 14th day (LEDT delay) for 14 days experimental period. The LED parameters was 22 mW CW of optical output power, distributed in an irradiation area of 0.5 cm(2), with an irradiation time of 170 seconds, the applied energy density was 7.5 J/cm(2) in contact. The therapy was initiated 12 hours after the tendinitis induction, with a 48-hour interval between the irradiations. The histological analysis and inflammatory mediators were quantified.

RESULTS

Our results showed that LED decreases the inflammatory cells influx and mRNA expression to IL-1 beta, IL-6, tumor necrosis factor-alpha (TNF-alpha) in both phase, and cyclooxygenase-2 (COX-2) just in initial phase (P < 0.05).

CONCLUSION

Our results suggest that the anti-inflammatory therapy with low-power LED (880 nm) enhanced the tissue response in all groups. We can conclude that the LED was able to reduce signs of inflammation in collagenase-induced tendinitis in rats by reducing the number of inflammatory cells and decrease mRNA expression of cytokines.

Effects of low-level laser therapy on expression of TNF-α and TGF-β in skeletal muscle during the repair process

The aim of the present study was to determine the effect of low-level laser therapy (LLLT) on the expression of TNF-α and TGF-β in the tibialis anterior muscle of rats following cryoinjury. Muscle regeneration involves cell proliferation, migration and differentiation and is regulated by growth factors and cytokines. A growing body of evidence suggests that LLLT promotes skeletal muscle regeneration by reducing the duration of acute inflammation and accelerating tissue repair. Adult male Wistar rats (n = 35) were randomly divided into three groups: control group (no lesion, untreated, n = 5), cryoinjury without LLLT group (n = 15), and cryoinjury with LLLT group (n = 15). The injured region was irradiated three times a week using an AlGaInP laser (660 nm; beam spot 0.04 cm(2), output power 20 mW, power density 500 mW/cm(2), energy density 5 J/cm(2), exposure time 10 s). Muscle remodeling was evaluated at 1, 7 and 14 days (long-term) following injury. The muscles were removed and total RNA was isolated using TRIzol reagent and cDNA synthesis. Real-time polymerase chain reactions were performed using TNF-α and TGF-β primers; GAPDH was used to normalize the data. LLLT caused a decrease in TNF-α mRNA expression at 1 and 7 days following injury and in TGF-β mRNA expression at 7 days following cryoinjury in comparison to the control group. LLLT modulated cytokine expression during short-term muscle remodeling, inducing a decrease in TNF-α and TGF-β.

Low-level laser therapy (LLLT; 780 nm) acts differently on mRNA expression of anti- and pro-inflammatory mediators in an experimental model of collagenase-induced tendinitis in rat

Low-level laser therapy (LLLT) has been found to produce anti-inflammatory effects in a variety of disorders. Tendinopathies are directly related to unbalance in expression of pro- and anti-inflammatory cytokines which are responsible by degeneration process of tendinocytes. In the current study, we decided to investigate if LLLT could reduce mRNA expression for TNF-α, IL-1β, IL-6, TGF-β cytokines, and COX-2 enzyme. Forty-two male Wistar rats were divided randomly in seven groups, and tendinitis was induced with a collagenase intratendinea injection. The mRNA expression was evaluated by real-time PCR in 7th and 14th days after tendinitis. LLLT irradiation with wavelength of 780 nm required for 75 s with a dose of 7.7 J/cm(2) was administered in distinct moments: 12 h and 7 days post tendinitis. At the 12 h after tendinitis, the animals were irradiated once in intercalate days until the 7th or 14th day in and them the animals were killed, respectively. In other series, 7 days after tendinitis, the animals were irradiated once in intercalated days until the 14th day and then the animals were killed. LLLT in both acute and chronic phases decreased IL-6, COX-2, and TGF-β expression after tendinitis, respectively, when compared to tendinitis groups: IL-6, COX-2, and TGF-β. The LLLT not altered IL-1β expression in any time, but reduced the TNF-α expression; however, only at chronic phase. We conclude that LLLT administered with this protocol reduces one of features of tendinopathies that is mRNA expression for pro-inflammatory mediators.