Low-intensity laser therapy efficacy evaluation in FVB mice subjected to acute and chronic arthritis

A novel investigational preclinical model to assess fluence rate for dental oral craniofacial tissues

OBJECTIVE

Photodynamic Therapy (PDT) and Photobiomodulation (PBM) are recognized for their potential in treating head and neck conditions. The heterogeneity of human tissue optical properties presents a challenge for effective dosimetry. The porcine mandible cadaver serves as an excellent model and has several similarities to human tissues of the dental oral craniofacial complex. This study aims to validate a novel modeling system that will help refine PDT and PBM dosimetry for the head and neck region.

METHODS AND MATERIALS

Light transmission was analyzed through several tissue combinations at distances of 2 mm to 10 mm. Maximum light fluence rates (mW/cm2) were compared across tissue types to reveal the effects of tissue heterogeneity.

RESULTS

The study revealed that light fluence is affected by tissue composition, with dentin/enamel showing reduced transmission and soft tissue regions exhibiting elevated values. The porcine model has proven to be efficient in mimicking human tissue responses to light, enabling the potential to optimize future protocols.

CONCLUSION

The porcine mandible cadaver is a novel model to understand the complex interactions between light and tissue. This study provides a foundation for future investigations into dosimetry optimization for PDT and PBM.

Resistance exercise and low-level laser therapy improves grip strength and morphological aspects in the ankle joint of Wistar rats with experimental arthritis

Rheumatoid arthritis (RA) is an inflammatory disease mainly affecting synovial joints. Photobiomodulation through low-level laser therapy (LLLT) and resistance exercise may improve the inflammatory process. Therefore, we analyzed the effects of resistance exercise, LLLT, and the combination of both treatments on hind paw grip strength and ankle joint histomorphometric aspects of Wistar rats subjected to experimental RA. A total of 64 male Wistar rats were divided into eight groups: control, control LLLT, control exercise, control LLLT and exercise, arthritis, arthritis LLLT, arthritis exercise, and arthritis LLLT and exercise groups. The experimental RA was induced by a complete Freund's adjuvant injection into the knee joint cavity. Climbing exercises and LLLT (660 nm; 5 J/cm² per point) were performed as the treatment. In addition, muscle strength was evaluated using the grip strength test, and morphometric evaluations were performed on the ankle joint. Generalized mixed models and multivariate analysis of variance tests were used for statistical analysis. Statistical significance was set at a p-value of .05. Arthritis LLLT, exercise, and LLLT and exercise had positive effects on grip strength between the groups (F[7.56] = 5.8, p < .004) and within the groups (F[4.3] = 9.9, p < .002) throughout the evaluations. Morphometry revealed degenerative lesions in the ankle joint as subintima with angiogenesis, inflammatory cells, flocculated articular cartilage, chondrocyte disorganization, and pannus in the arthritis group (p < .001). The treated groups exhibited morphological characteristics similar to those of the control group. LLLT and resistance exercise restored muscle strength and morphological aspects of the ankle joint in rats with experimentally induced RA.

Effects of Laser Therapy on Rheumatoid Arthritis: A Systematic Review and Meta-analysis

OBJECTIVE

The aim of the study was to examine the effects of laser therapy on rheumatoid arthritis.

DESIGN

A search of controlled trials was conducted in different medical electronic databases. The primary outcome was immediate pain relief after treatment. Secondary outcomes were level of functional disability, morning stiffness duration, and 3-mo follow-up for pain.

RESULTS

Ten trials met the inclusion criteria. Rheumatoid arthritis treatment with laser therapy significantly improved immediate pain relief (standardized mean difference = -0.839, 95% confidence interval = -1.336 to -0.343) and overall functional score (standardized mean difference = -0.309, 95% confidence interval = -0.587 to -0.031). There was no significant improvement in morning stiffness duration (standardized mean difference = -0.519, 95% confidence interval = -1.176 to 0.138), and 3-mo follow-up for pain (standardized mean difference = -1.125, 95% confidence interval = -2.311 to 0.061). There was no publication bias (Egger regression, P = 0.277). However, heterogeneity was noted despite the removal of an outlier (Q = 18.646, I2 = 57.096). Results of subgroup analyses suggested that high-intensity laser therapy and nerve irradiation are better suited for immediate pain relief. Meta-regression analyses showed no significant linear relationship between the treatment effect with laser wavelength or number of treatment sessions.

CONCLUSIONS

Laser therapies provide significant immediate pain relief and improve function for rheumatoid arthritis patients, but without significant improvement in morning stiffness duration and 3-mo follow-up for pain.Systematic review registration number: CRD42020192906.

Photobiomodulation Therapy (Light-Emitting Diode 630 nm) Favored the Oxidative Stress and the Preservation of Articular Cartilage in an Induced Knee Osteoarthritis Model

Objective: To evaluate the effects of photobiomodulation (PBM) therapy on oxidative stress and histological aspects of knee osteoarthritis (OA) induced by sodium monoiodoacetate in Wistar rats. Background: OA is a chronic degenerative disease. In addition to the inflammatory role, other factors, such as redox balance, appear to contribute to changes in the articular cartilage, the main articular structure affected. PBM therapy using light-emitting diode (LED) has been proposed to treat the disease by favoring anti-inflammatory effects and modulating markers of oxidative stress, acting on the degenerative process of cartilage. Methods: Twenty-seven male rats were separated into three groups: control (CG), OA (OAG), and LED treatment (LEDG). In the LED group, PBM (LED 630 nm, 300 mW, 9 J/cm², 0.3 W/cm², 30 sec) was applied, starting 24 h after induction, three times per week, for 8 weeks. Cartilage thickness, number of chondrocytes, enzymatic antioxidant defenses [superoxide dismutase (SOD) and catalase (CAT)], oxidative damage [thiobarbituric acid reactive substances (TBARS)], and nonenzymatic defense (ferric reducing antioxidant power) were analyzed. Results: The LEDG had higher average cartilage thickness compared with the OAG and had similar thickness to the CG. Also, the number of chondrocytes was similar to the CG. In the oxidative stress analysis, the LEDG presented antioxidant enzymatic activity (SOD and CAT) higher than the CG, and presented concentration of TBARS lower than the CG and OAG groups. Conclusions: PBM therapy was effective in recovering oxidative stress and preserving the articular cartilage aspects in a knee OA animal model.

Effectiveness of Led Photobiomodulation Therapy on Treatment With Knee Osteoarthritis: A Rat Study

OBJECTIVE

The present study aimed to evaluate the effectiveness of photobiomodulation therapy by light-emitting diode on osteoarthritis treatment in the knees of rats.

DESIGN

Twenty male Wistar rats were randomly assigned into two experimental groups: OAC: animals subjected to induction of osteoarthritis, without therapeutic intervention and the group OAL: animals subjected to induction of osteoarthritis treated with light-emitting diode photobiomodulation therapy (850 nm, 200 mW, 6 J).

RESULTS

The results of gait analysis showed no statistical difference between the groups. The histological findings showed that the OAL group presented abnormal chondrocyte orientation, yet with less irregularities along fibrillation and the joint tissue. Thus, it presented a lower degenerative process when evaluated by the Osteoarthritis Research Society International. Likewise, in the immunohistochemical analysis, the OAL group showed higher collagen 2 and transforming growth factor β immunoexpression when compared with the OAC group.

CONCLUSIONS

Given the above, it is possible to suggest that the photobiomodulation therapy by light-emitting diode had positive effects on the expression of extracellular matrix proteins responsible for synthesis of articular tissue.

Photobiostimulation activity of different low-level laser dosage on masticatory muscles and temporomandibular joint in an induced arthritis rat model

This study aimed to investigate the anti-inflammatory effects of different dosage of low-level laser therapy (LLLT) in an experimental model of temporomandibular joint (TMJ) arthritis. One hundred male Wistar rats were used and divided into the following groups: CG, control group; AG, animals group with left TMJ arthritis induced by intra-articular injection of Complete Freund's adjuvant - CFA; LG5, LG10 and LG20 - animals with arthritis and treated with LLLT at doses 5, 10, and 20 J/cm², respectively. Morphological analysis was performed by TMJ histological sections stained with hematoxylin-eosin (HE), picrosirius (PSR), and toluidine blue (TB), as well as histomorphometric evaluation of cartilage, articular disc, and masticatory muscles. The amount of feed consumed within 3 weeks was evaluated, and biochemical analysis of TMJ tissues included measurement of sulfated glycosaminoglycans (GAGs), matrix metalloproteinases (MMPs) 2 and 9 zymography, and ELISA for cytokines IL-6, TNF-α, and IL-1β. Only the 20 J/cm² dose promoted higher feed intake compared to AG. On the other hand, all LLLT doses promoted better organization of articular disc collagen fibers, greater number of proteoglycans in articular cartilage, increased area and diameter of left lateral pterygoid fibers, reduced latent and active MMP 9 and 2 activity, and lower IL-1β concentration compared to AG. Considering the study limitations, it was observed that LLLT treatments were effective in protecting and tissue cleansing joint structures, accelerating tissue repair, especially at lower doses.

Physical exercise and low-level laser therapy on the nociception and leukocyte migration of Wistar rats submitted to a model of rheumatoid arthritis

Rheumatoid arthritis denotes hyperplasia and intense inflammatory process. Treatment involves exercise protocols and use of resources such as low-level laser therapy (LLLT) to modulate the inflammatory process and maintain physical capacity. The objective was to investigate whether treatment with LLLT and exercise modulates the inflammatory process and peripheral functionality. Sample is composed of 128 male rats, separated into three groups, control, treated and untreated, in the acute and chronic period of the disease with 64 animals in each group, divided into 8 subgroups with n = 8. The animals were immunized with injection at the base of the tail and 7 days after intra-articular injection with complete Freund adjuvant (CFA) for lesion groups, and saline solution for the controls. Joint disability was evaluated by PET (paw elevation time) and joint edema and treated with LLLT and/or resisted stair climbing exercise. Normality Shapiro-Wilk test, ANOVA mixed for the functional analyses, and ANOVA one-way for the variables of cellular differentiation, with Bonferroni post hoc, p = 5% were used. For the evaluations of joint disability and nociception, there was a significant difference between the evaluations, the groups, and the interaction groups-evaluations. The treated groups showed recovery of functionality; it is still verified that laser therapy increased the nociceptive threshold of the chronic inflammatory period, and the exercise reflected in significant functional improvement and modulation of the inflammatory process both in the acute and chronic periods. LLLT, resistance exercise, or a combination of treatments had a positive effect on the modulation of the inflammatory process, reducing the migration of leukocytes, in addition to helping the return of peripheral functionality by reducing joint disability in a model of rheumatoid arthritis induced by CFA in rats.

Laser Light Therapy in Inflammatory, Musculoskeletal, and Autoimmune Disease

PURPOSE OF REVIEW

The goal of this review is to summarize the field to date and to discuss strengths and limitations of low-level laser (light) therapy (LLLT) for the future investigation as a treatment of inflammatory disease.

RECENT FINDINGS

LLLT is a promising therapeutic, particularly for those diseases of skin and joints because they are most accessible to treatment. Indeed, the known mechanisms of LLLT support its use for anti-inflammatory purposes, as well as stimulation of tissue growth and repair. Although the standard of care for the majority of inflammatory diseases is immunosuppressive agents such as corticosteroids with undesirable toxicities, LLLT offers a unique approach by being non-invasive and incurring minimal side effects. It is also relatively inexpensive and accessible and even has the possibility to be patient directed at home. There is evidence that LLLT is able to modulate the immune system at the skin and joint, and it has been shown to be efficacious in humans by affecting bacterial colonization as it may pertain to chronic rhinosinusitis. However, there is variability in the methods of laser application as well as a lack of evidence for laser type, dose-ranging studies, and wavelength selection that create barriers to the implementation of LLLT without further more rigorous and standardized study. The heterogeneity makes it difficult to draw strong conclusions about the efficacy of LLLT and its mechanisms.

Photobiomodulation using high- or low-level laser irradiations in patients with lumbar disc degenerative changes: disappointing outcomes and remarks

Background

Laser therapy seems to be a beneficial physical agent for chronic low back pain (LBP), and it is commonly used in the clinical rehabilitation practice. However, there are still no indisputable and clearly defined protocols and practical guidelines, and further, the methodology of the previous reports leaves many unsatisfied and raises some reservations.

Objective

The aim of this study was to evaluate the effectiveness of low-level laser therapy (LLLT) and high-intensity laser therapy (HILT) in patients with lumbar disc degenerative changes based on the analysis of the short- and long-term results and in comparison with the placebo effect.

Design

This study was a prospective and placebo-controlled clinical trial.

Materials and methods

A group of 68 participants were qualified for the therapy and were assigned to four comparative groups in the order they volunteered: HILT of 1,064 nm, 60 J/cm², 10 minutes (HILT); sham (HILT placebo); LLLT of 785 nm, 8 J/cm², 8 minutes; and sham (LLLT placebo). The following tests were used to assess the effectiveness of treatment: 1) the visual analogue scale; 2) the Laitinen Questionnaire Indicators of Pain; 3) the Oswestry Disability Index; 4) the Roland–Morris Disability Questionnaire; 5) Lasegue test; and 6) Schober’s test. All measurements were carried out before and after irradiations (3 weeks) and in follow-ups (1 and 3 months).

Results

After applying verum or placebo laser irradiation, therapeutic progress was observed in all comparative groups; however, no statistically significant differences were observed among the procedures.

Conclusion

The high- and low-energy laser therapy methods used in the present article are ineffective in relation to patients with lumbar disc degenerative changes in both the short- and long-term perspectives and do not show a significant advantage over the placebo effect.