Low-level laser therapy modulates pro-inflammatory cytokines after partial tenotomy

Histological, Physiological and Biomechanical Effects of Low-Level Laser Therapy on Tendon Healing in Animals and Humans: A Systematic Review

Low-level Laser Therapy (LLLT) was widely used in clinical practice for tendon disorders. However, the underlying mechanisms and effectiveness of LLLT in treating tendon injury remain unclear. Therefore, the present study was conducted aiming to summarize the evidence regarding the histological, physiological, and biomechanical effects of LLLT on tendon healing in animal and human models. Four databases were searched for relevant literature. Four independent reviewers screened abstracts and full-text articles, extracted relevant data, evaluated the risk of bias, and quantified the quality of evidence. Database searches yielded 1400 non-duplicated citations. Fifty-five studies were included (50 animal and five human studies). Animal studies revealed that LT had stimulating effects on collagen organization, collagen I and collagen II formation, matrix metalloproteinase (MMP)-8, transforming growth factor β1, vascular endothelial growth factor, hydroxyproline, maximum load, maximum elongation before breaking, and tendon stiffness. However, LLLT had inhibitory effects on the number of inflammatory cells, histological scores, relative amount of collagen III, cyclooxygenase-2, prostaglandin E2 (PGE2), interleukin-6, tumor necrosis factor-α, MMP-1, and MMP-3. Although one human study found that LLLT reduced the concentration of PGE2 in peritendinous tissue of the Achilles tendon, other human studies revealed that the effects of LLLT on the physiology and biomechanics of human tendons remained uncertain. LLLT facilitates tendon healing through various histological, physiological, and biomechanical effects in animal models. Only post-LLLT anti-inflammatory effects were found in human studies.

Changes in Cell Biology under the Influence of Low-Level Laser Therapy

Low-level laser therapy (LLLT) has become an important part of the therapeutic process in various diseases. However, despite the broad use of LLLT in everyday clinical practice, the full impact of LLLT on cell life processes has not been fully understood. This paper presents the current state of knowledge concerning the mechanisms of action of LLLT on cells. A better understanding of the molecular processes occurring within the cell after laser irradiation may result in introducing numerous novel clinical applications of LLLT and potentially increases the safety profile of this therapy.

Infliximab prevents systemic bone loss and suppresses tendon inflammation in a collagen-induced arthritis rat model

Reduced Bone Mineral Density (BMD) and tendon abnormalities, such as tenosynovitis and enthesitis, are prevalent comorbidities in patients with rheumatoid arthritis (RA). The aim of the present study was to investigate the effect of chronic treatment with infliximab on BMD and tendon inflammation in an animal model of inflammatory arthritis. Collagen-Induced Arthritis (CIA) was induced in rats, followed by long-term intraperitoneal administration of infliximab. Two additional groups of animals received methotrexate either as a monotherapy or as a co-treatment to infliximab. BMD was evaluated by Micro-Computed Tomography (Micro-CT) and bone histological examination. Tendon inflammation was assessed histologically and by quantitative ELISA analysis of pro-inflammatory cytokines in tendon tissues. Both methotrexate and infliximab treatment alleviated joint inflammation and reduced paw edema. Infliximab-treated animals exhibited an improved trabecular microarchitecture on micro-CT and histological analysis compared to both non-treated and methotrexate-treated animals. Infliximab almost reversed the pathological changes in tendons induced by CIA. Finally, we observed statistically significant declines in tendon TNF-a and IL-23 levels after infliximab treatment. Our study provides evidence that infliximab prevents arthritis-related osteoporosis and suppresses tendon inflammation in an animal model of inflammatory arthritis, in addition to controlling disease activity. These findings offer perspectives for the management of osteoporosis and enthesitis in RA.

Efficacy and safety of 755 nm Q-switched Alexandrite Laser for Hori's nevus: a retrospective analysis of 482 Chinese women

To evaluate the efficacy and safety of 755 nm Q-Switched alexandrite laser for Hori's nevus in a large cohort of Chinese women. We retrospectively analyzed the efficacy and safety of 755 nm Q-Switched alexandrite laser for Hori's nevus. Reduction in pigment was evaluated using a 4-score method. A total of 482 patients, aged 16 to 52 years, were included in this analysis. Patients were treated with 755 nm Q-Switched alexandrite laser at fluence levels of 5-8 J/cm² for 2-4 treatment sessions. Following the treatments, 53% of patients showed over 75% reductions in pigment while 50-75% reductions in pigment were observed in 28% of patients. The rest displayed less than 50% improvements. Efficacy was positively correlated with the number of treatment sessions (p < 0.0001). Adverse reactions were temporary, mild erythema, and edema. A small portion of patients (15%) had hyperpigmentation, which disappeared within 2-6 months. 755 nm Q-Switched alexandrite laser is safe and has moderate benefits for Hori's nevus. Because its efficacy is positively correlated with the number of treatment sessions, increase in treatment sessions possibly could achieve a better outcome.

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

This systematic review analyzed the light parameters and the effects of photobiomodulation therapy (PBMT) through low-level laser therapy (LLLT) and/or LED (light-emitting diode) on tendon repair of rats submitted to calcaneal injury. This study was conducted in accordance with the guidelines of the Preferred Reporting Items for Meta-Analysis, and PubMed and MEDLINE databases were accessed to search eligible studies published in English. The search terms were as follows: "Achilles tendon" or "Calcaneal tendon" or "tendon injuries" or "soft tissue injuries" and "tendinopathy" or "tendinitis" and "low-level light therapy" or "low-level laser therapy" or "low intensity power therapy" or "light-emitting diode" or photobiomodulation." The SYRCLE (SYstematic Review Center for Laboratory animal Experimentation) risks of bias was used to assess the risk of bias for selected studies. A total of 225 studies were found based on the descriptors used, and only 33 studies were eligible. Light parameters identified per point of irradiation were approximately 60 mW (continuous mode at infrared spectra), 2 W cm^-2 , 2 J and 45 J cm^-2 . Light parameters at red spectra, continuous versus pulsed mode, and PBMT combined or compared with other therapies such as ultrasound, and studies using unhealthy rats (ovariectomized and/or diabetic models) were also identified and grouped according to these similarities. The main effects found were decreased inflammatory markers and signs of inflammatory process. PBMT (laser/LED) has positive effects in reducing the inflammatory and time for tissue repair in animal models of tendon injury and/or tendinitis using parameters identified.

Penetration Profiles of a Class IV Therapeutic Laser and a Photobiomodulation Therapy Device in Equine Skin

Photobiomodulation therapy (PBMT) effects depend on the energy settings and laser penetration. We investigated the penetration time profiles of two different light therapy devices, at the dark and light skin regions in horses. Six light skin and six dark skin adult clinically healthy Arab and Quarter horses were used. A cutometer was used to measure the width of the skin fold from both sides of the cervical area, followed by three measurements of the thickness of the same skin fold by transversal and longitudinal ultrasonography (US). The depth of light penetration was compared based on the percentage of penetration versus power, between a portable PBMT device versus a class IV laser device. The laser mean power output was measured with an optical power meter system for 120 seconds after penetrating the skin. Skin width and laser penetration were compared among equipment by paired "t" test. There was no difference in the width of the skin fold between measurements acquired by the cutometer against either longitudinal or transversal US or between the US measurements at cervical versus metacarpus area. Light penetration was greater in both kinds of skins in the PBMT (0.01303 ± 0.00778) versus class IV laser (0.00122 ± SD 0.00070) (P < .001). The PBMT device provided a greater energy penetration than the class IV laser in unclipped light and dark skin, suggesting that the former may produce a better therapeutic effect. The color of the skin changes penetration profiles of PBMT.

In vitro effect of low-level laser therapy on the proliferative, apoptosis modulation, and oxi-inflammatory markers of premature-senescent hydrogen peroxide-induced dermal fibroblasts

Skin aging is a complex biological process induced by intrinsic and extrinsic factors which is characterized by clinical and cellular changes, especially dermal fibroblasts. It is possible that, some procedures, such as low-level laser therapy (LLLT), could decelerate this process. To test this hypothesis, this study evaluated the in vitro LLLT on dermal fibroblast cell line (HFF-1) with premature senescence H2O2-induced. HFF-1 cells were cultured in standardized conditions, and initially H2O2 exposed at different concentrations. Fibroblasts were also just exposed at different LLLT (660 nm) doses. From these curves, the lowest H2O2 concentration that induced indicators of premature senescence and the lowest LLLT doses that triggered fibroblast proliferation were used in all assays. Cellular mortality, proliferation, and the levels of oxidative, inflammatory cytokines, apoptotic markers, and of two growth signaling molecules (FGF-1 and KGF) were compared among treatments. The H2O2 at 50 μM concentration induced some fibroblast senescence markers and for LLLT, the best dose for treatment was 4 J (p < 0.001). The interaction between H2O2 at 50 μM and LLLT at 4 J showed partially reversion of the higher levels of DNA oxidation, CASP 3, CASP 8, IL-1B, IL-6, and INFy induced by H2O2 exposure. LLLT also trigger increase of IL-10 anti-inflammatory cytokine, FGF-1 and KGF levels. Cellular proliferation was also improved when fibroblasts treated with H2O2 were exposed to LLLT (p < 0.001). These results suggest that in fibroblast with some senescence characteristics H2O2-induced, the LLLT presented an important protective and proliferative action, reverting partially or totally negative effects triggering by H2O2.

Chronical treatment with sildenafil causes Achilles tendinopathy in rats

AIMS

The primary goal was to assess the effects of chronic sildenafil treatment over the Achilles tendons in rats.

MAIN METHODS

Animals were divided into two groups, control and sildenafil administration (n = 5). After 60 days, the tendons were subject to biochemical and image analysis to compare tendons between the groups: collagen I and decorin content, polarisation microscopy and birefringence analysis, and tissue zymography.

KEY FINDINGS

The animals exposed to sildenafil presented a much less organised tendon matrix, with reduced collagen I and non-collagenous protein content and a much higher decorin content.

SIGNIFICANCE

The results observed in the animals can be characterised as tendinopathy, a condition not yet described as a sildenafil side effect.

Cytokines in tendon disease: A Systematic Review

OBJECTIVES

Emerging evidence indicates that tendon disease is an active process with inflammation that is critical to disease onset and progression. However, the key cytokines responsible for driving and sustaining inflammation have not been identified.

METHODS

We performed a systematic review of the literature using MEDLINE (U.S. National Library of Medicine, Bethesda, Maryland) in March 2017. Studies reporting the expression of interleukins (ILs), tumour necrosis factor alpha (TNF-α) and interferon gamma in diseased human tendon tissues, and animal models of tendon injury or exercise in comparison with healthy control tissues were included.

RESULTS

IL-1β, IL-6, IL-10, and TNF-α are the cytokines that have been most frequently investigated. In clinical samples of tendinopathy and tendon tears, the expression of TNF-α tended not to change but IL-6 increased in tears. Healthy human tendons showed increased IL-6 expression after exercise; however, IL-10 remained unchanged. Animal tendon injury models showed that IL-1β, IL-6, and TNF-α tend to increase from the early phase of tendon healing. In animal exercise studies, IL-1β expression showed a tendency to increase at the early stage after exercise, but IL-10 expression remained unchanged with exercise.

CONCLUSIONS

This review highlights the roles of IL-1β, IL-6, IL-10, and TNF-α in the development of tendon disease, during tendon healing, and in response to exercise. However, there is evidence accumulating that suggests that other cytokines are also contributing to tendon inflammatory processes. Further work with hypothesis-free methods is warranted in order to identify the key cytokines, with subsequent mechanistic and interaction studies to elucidate their roles in tendon disease development.Cite this article: W. Morita, S. G. Dakin, S. J. B. Snelling, A. J. Carr. Cytokines in tendon disease: A Systematic Review. Bone Joint Res 2017;6:656-664. DOI: 10.1302/2046-3758.612.BJR-2017-0112.R1.