Biomodulation of Inflammatory Cytokines Related to Oral Mucositis by Low-Level Laser Therapy

Effects of low-level laser therapy on burning pain and quality of life in patients with burning mouth syndrome: a systematic review and meta-analysis

BACKGROUND

Burning mouth syndrome (BMS) is a complex chronic pain disorder that significantly impairs patients' quality of life. Low-level laser therapy (LLLT) uses infrared or near-infrared light to produce analgesic, anti-inflammatory, and biological stimulation effects. The aim of this systematic review is to evaluate the effect of LLLT on burning pain, quality of life, and negative emotions in patients with BMS.

METHODS

The PubMed, Embase, Cumulative Index of Nursing and Allied Health Literature (CINAHL), Cochrane Library, Web of Science, and Scopus databases were searched up January 2023 to identify relevant articles. All randomized controlled trials that were published in English and examined the use of LLLT treatment for BMS were included. The methodological quality of the included trials was assessed using the Cochrane risk of bias tool for randomized controlled trials (RCTs). A meta-analysis was performed to evaluate burning pain, quality of life, and negative emotions. Sensitivity, subgroup, and funnel plot analyses were also carried out.

RESULTS

Fourteen RCTs involving a total of 550 patients with BMS met the inclusion criteria. The results showed that LLLT (measured by the Visual Analog Scale; SMD: -0.87, 95% CI: -1.29 to -0.45, P < 0.001) was more effective for reducing burning pain than placebo LLLT or clonazepam. LLLT improved quality of life (evaluated by the Oral Health Impact Profile-14; SMD: 0.01, 95% CI: -0.58 to 0.60, P = 0.97) and negative emotions (evaluated by the Hospital Anxiety and Depression Scale; SMD: -0.12, 95% CI: -0.54 to 0.30, P = 0.59), but these effects were not statistically significant.

CONCLUSIONS

The meta-analysis revealed that LLLT may be an effective therapy for improving burning pain in patients with BMS, and producing a positive influence on quality of life and negative emotions. A long-term course of intervention, a larger sample size, and a multidisciplinary intervention design are urgently needed in future research.

TRIAL REGISTRATION

PROSPERO registration number: CRD42022308770.

Photobiomodulation Reduces the Cytokine Storm Syndrome Associated with COVID-19 in the Zebrafish Model

Although the exact mechanism of the pathogenesis of coronavirus SARS-CoV-2 (COVID-19) is not fully understood, oxidative stress and the release of pro-inflammatory cytokines have been highlighted as playing a vital role in the pathogenesis of the disease. In this sense, alternative treatments are needed to reduce the level of inflammation caused by COVID-19. Therefore, this study aimed to investigate the potential effect of red photobiomodulation (PBM) as an attractive therapy to downregulate the cytokine storm caused by COVID-19 in a zebrafish model. RT-qPCR analyses and protein-protein interaction prediction among SARS-CoV-2 and Danio rerio proteins showed that recombinant Spike protein (rSpike) was responsible for generating systemic inflammatory processes with significantly increased levels of pro-inflammatory (il1b, il6, tnfa, and nfkbiab), oxidative stress (romo1) and energy metabolism (slc2a1a and coa1) mRNA markers, with a pattern similar to those observed in COVID-19 cases in humans. On the other hand, PBM treatment was able to decrease the mRNA levels of these pro-inflammatory and oxidative stress markers compared with rSpike in various tissues, promoting an anti-inflammatory response. Conversely, PBM promotes cellular and tissue repair of injured tissues and significantly increases the survival rate of rSpike-inoculated individuals. Additionally, metabolomics analysis showed that the most-impacted metabolic pathways between PBM and the rSpike treated groups were related to steroid metabolism, immune system, and lipid metabolism. Together, our findings suggest that the inflammatory process is an incisive feature of COVID-19 and red PBM can be used as a novel therapeutic agent for COVID-19 by regulating the inflammatory response. Nevertheless, the need for more clinical trials remains, and there is a significant gap to overcome before clinical trials can commence.

Correlations between the severity of radiation-induced oral mucositis and salivary epidermal growth factor as well as inflammatory cytokines in patients with head and neck cancer

BACKGROUND

This study aimed to investigate correlations of the severity of radiation-induced oral mucositis (RIOM) with epidermal growth factor (EGF) and inflammatory cytokines in patients with head and neck cancer (HNC).

METHODS

Levels of inflammatory cytokines and EGF in saliva of HNC patients were measured. Correlations of inflammatory cytokines and EGF levels with RIOM severity and pain degree, and their diagnostic values on RIOM severity were determined.

RESULTS

Elevated IFN-γ, TNF-α, IL-2, and IL-6 levels, and reduced IL-4, IL-10, and EGF levels were found in patients with severe RIOM. IFN-γ, TNF-α, IL-2, and IL-6 were positively correlated with RIOM severity, while IL-10, IL-4, and EGF were negatively correlated with it. All factors were effective in predicting the severity of RIOM.

CONCLUSION

IFN-γ, TNF-α, IL-2, and IL-6 in saliva of patients with HNC are positively correlated with the severity of RIOM, and IL-4, IL-10, and EGF were negatively correlated with it.

Photobiomodulation for Chemotherapy-Induced Oral Mucositis in Pediatric Patients

Oral mucositis (OM) is a common side effect in patients undergoing chemotherapy (CT), especially in children due to their rapid epithelial mitotic rate. It has been associated with a significant reduction in life quality since it leads to pain, an inadequate intake of nutrients, an increased risk of opportunistic infections, and interruptions of CT. Photobiomodulation (PMB) with low-level laser therapy (LLLT) has shown faster healing, reduction in pain, and the reduced use of analgesic compared to placebo groups. The purpose of this review is to analyze and compare the existing clinical trials and identify their shortcomings in hope to make future research easier. Using MeSH terms and keywords, the Embase, Medline, and PubMed databases we searched for the period of the last 5 years. We identified a total of 15 clinical trials, with a total of 929 pediatric patients analyzed in this review. We compared different light sources and other laser technique characteristics used in clinical trials such as wavelength, energy and power density, spot size, irradiation time, PBM protocol, and OM evaluation. The main findings show inconsistent laser parameter quotations, differences in the PBM protocol along with a laser application technique, and a lack of clinical trials. Based on that, more studies with a high methodological quality should be conducted in order to provide a unified PBM protocol suitable for the pediatric population.

Effects of Photobiomodulation on Oral Mucositis: Visualization and Analysis of Knowledge

This review article mapped and analyzed the most cited articles on the association of photobiomodulation (PBM) with oral mucositis (OM) and the evolution of clinical protocols in the area. A comprehensive search was performed on the Web of Science Core Collection (WoS-CC) database, leading to the extraction of information such as title, authors, abstract, journal name, number, average of citations, study design, year of publication, institutions, continents, countries, type of laser used, irradiated anatomical points, primary anti-cancer therapy, and laser parameters. Among those, clinical trials and literature reviews were the most common study designs. The main type of laser used was the InGaAlP diode, with a wavelength ranging from 630-660 nm, power going in 40-100 mW, and energy density ranging from 0.375-22 J/cm². As for the anatomical sites irradiated by PBM, the cheek mucosa, upper and lower lips, lateral tongue, and bottom of the mouth stood out. This analysis highlights an increasing interest in PBM as a supportive treatment in cases of OM, as well as the evolution of the technique, types of laser devices, and protocols used.

Regulation of interleukin-6 and matrix metalloproteinases syntheses by bioflavonoids and photobiomodulation in human gingival fibroblasts

This study aimed to evaluate the separately effects of bioflavonoids proanthocyanidins, from grape seed extract (GSE) and synthetic naringenin (NA), as well as photobiomodulation (PBM) by low-level laser therapy on interleukin (IL)-6 and matrix metalloproteinases (MMPs) syntheses by human gingival fibroblasts (HGF). For this purpose, a connective tissue exposure (ulceration) model of HGF, stimulated with tumor necrosis factor-alpha (TNF-α), was used. Initially, the highest non-cytotoxic and non-genotoxic concentrations of bioflavonoids were determined by cell viability and micronuclei formation assays. Then, HGF were exposed to different stimuli: culture medium (negative control), dimethyl sulfoxide (DMSO), TNF-α, NA, GSE, TNF-α + NA, TNF-α + GSE, PBM (3 J/cm², 0.025 W, 780 nm), and TNF-α + PBM. Next, IL-6, MMP-2, and MMP-9 syntheses were assessed. The concentration of 10 μg/mL of bioflavonoids increased cell viability at 24 and 48 h and did not present cytotoxic or genotoxic effects on HGF after 24, 48, and 72 h of contact. This concentration was selected for the assessment of bioflavonoids potential in modulating inflammatory mediators. TNF-α exposure enhanced IL-6 (170%), MMP-2 (10%), and MMP-9 (20%) syntheses, while a decrease of MMP-2 by 55% after exposure to TNF-α + GSE and 20% after TNF-α + NA and TNF-α + PBM was observed. MMP-9 synthesis was decreased by 35% after TNF-α + NA, 20% after TNF-α + GSE, and 30% after PBM. IL-6 was down-regulated by GSE in the presence of TNF-α (80%). In conclusion, TNF-α up-regulated IL-6 and MMPs, while bioflavonoids and PBM down-regulated MMP-2 and MMP-9 syntheses; GSE also decreased IL-6 synthesis, demonstrating the individual promising potential of these therapies for ulceration management.

Effect of GaAlAs 940 nm Photobiomodulation on palatal wound healing after free gingival graft surgery: a split mouth randomized controlled clinical trial

Background

The aim of this study was to evaluate the effects of photobiomodulation (PBM) on wound healing, pain, and discomfort at free gingival graft (FGG) donor sites.

Methods

Sixteen patients in need of bilateral FGG were selected for this randomized, controlled, triple-blinded, and split mouth clinical trial. The FGG donor sites in test group were treated with LLLT GaAlAs 940 nm, 5 J/cm² immediately after surgery and every other day within the following ten days. The control group received sham irradiation. Remaining Wound Area (RWA), Epithelialization and color match were evaluated on the day of surgery and 7, 14, 21, 28, and 60 days after surgery. A questionnaire was administered to measure pain and bleeding in the first ten days after surgery.

Results

RWA was significantly smaller in the test than control group on the days 7 (p < 0.001) and 14 (p = 0.048) after the surgery. Bleeding was higher in the test group than in the control group on the day of surgery (p = 0.046). Pain and discomfort at the palatal donor site, however, had no significant difference between laser and control group during 11 days after the surgery (p > 0.05), nor did the Color match scores on the 28th and 60th days after the surgery (p > 0.05).

Conclusions

It can be concluded that PBM enhances FGG donor site wound healing one and two weeks after the surgery.

Trial registration

IRCT2017092036203N2, registered 01.11.2017.

Cytokine-Mediated Inflammation in the Oral Cavity and Its Effect on Lipid Nanocarriers

Topical drug administration to the oral mucosa proves to be a promising treatment alternative for inflammatory diseases. However, disease-related changes in the cell barrier must be considered when developing such delivery systems. This study aimed at investigating the changes in the lining mucosa caused by inflammation and evaluating the consequences on drug delivery systems such as nanostructured lipid carriers (NLC). For this, TR146 cells were treated with inflammatory cytokines and bacterial components. Cell viability and integrity, reactive oxygen species (ROS), and interleukin (IL)-8 release were used as endpoints to assess inflammation. Translocation of phosphatidylserine, cytoskeletal arrangement, opening of desmosomes, and cell proliferation were examined. Transport studies with NLC were performed considering active and passive pathways. The results showed that IL-1ß and tumor necrosis factor α induced inflammation by increasing IL-8 and ROS production (22-fold and 2-fold). Morphologically, loss of cell–cell connections and formation of stress fibers and hyperplasia were observed. The charge of the cell membrane shifted from neutral to negative, which increased the absorption of NLC due to the repulsive interactions between the hydrophobic negative particles and the cell membrane on the one hand, and interactions with lipophilic membrane proteins such as caveolin on the other.

Photobiomodulation of oral fibroblasts stimulated with periodontal pathogens

Photobiomodulation (PBM) utilises light energy to treat oral disease, periodontitis. However, there remains inconsistency in the reporting of treatment parameters and a lack of knowledge as to how PBM elicits its molecular effects in vitro. Therefore, this study aimed to establish the potential immunomodulatory effects of blue and near infra-red light irradiation on gingival fibroblasts (GFs), a key cell involved in the pathogenesis of periodontitis. GFs were seeded in 96-well plates in media + / - Escherichia coli lipopolysaccharide (LPS 1 μg/ml), or heat-killed Fusobacterium nucleatum (F. nucleatum, 100:1MOI) or Porphyromonas gingivalis (P. gingivalis, 500:1MOI). Cultures were incubated overnight and subsequently irradiated using a bespoke radiometrically calibrated LED array (400-830 nm, irradiance: 24 mW/cm² dose: 5.76 J/cm²). Effects of PBM on mitochondrial activity (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) and adenosine triphosphate (ATP) assays, total reactive oxygen species production (ROS assay) and pro-inflammatory/cytokine response (interleukin-8 (IL-8) and tumour growth factor-β1 (TGFβ1)) were assessed 24 h post-irradiation. Data were analysed using one-way ANOVA followed by the Tukey test. Irradiation of untreated (no inflammatory stimulus) cultures at 400 nm induced 15%, 27% and 13% increases in MTT, ROS and IL-8 levels, respectively (p < 0.05). Exposure with 450 nm light following application of P. gingivalis, F. nucleatum or LPS induced significant decreases in TGFβ1 secretion relative to their bacterially stimulated controls (p < 0.001). Following stimulation with P. gingivalis, 400 nm irradiation induced 14% increases in MTT, respectively, relative to bacteria-stimulated controls (p < 0.05). These findings could identify important irradiation parameters to enable management of the hyper-inflammatory response characteristic of periodontitis.

Chemotherapy drugs and inflammatory cytokines enhance matrix metalloproteinases expression by oral mucosa cells

OBJECTIVE

Oral mucositis (OM), the most common side effect of cancer therapy, is associated with pro-inflammatory cytokines and matrix metalloproteinases (MMPs) increased expression. Although there are approaches for OM management, none is infallible, thus, elucidation of molecular events related to OM etiopathogenesis may improve current therapeutic strategies. This study assessed the influence of pro-inflammatory cytokines and chemotherapy drugs on MMPs expression and synthesis by oral mucosa cells.

DESIGN

Human gingival fibroblasts (HGF) were exposed to different concentrations of methotrexate (MTX) and 5-fluorouracil (5-FU); subsequentially, cell viability, nitric oxide and interleukin(IL)-6 production were evaluated to select the concentration of these drugs that could stimulate inflammatory phenotype without cytotoxic effects. Then, HGF and primary gingival keratinocytes (PGK) were subjected to different stimuli: culture medium (negative control), tumor necrosis factor-alpha (TNF-α - positive control), IL-6, IL-8, MTX, and 5-FU for 3, 6, 12, and 24 h. Next, gene expression and synthesis of MMP-2 and MMP-9 by HGF and MMP-3 by PGK were assessed.

RESULTS

At 6 h, MMP-2 synthesis increased 60 % after exposure to TNF-α and MTX, 40 % after IL-6, and 15 % after IL-8. At 12 h, MMP-9 synthesis increased 15 % after exposure to TNF-α, while MMP-3 synthesis increased 30 % after TNF-α, and 10 % after IL-8. TNF-α-treated groups presented increased gene expression of all MMPs evaluated. IL-8 and 5-FU increased MMP-2 and MMP-3 expression, while IL-6 and MTX augmented MMP-2 expression.

CONCLUSIONS

The chemotherapy drugs and cytokines investigated up-regulated MMPs expression by oral mucosa cells, which may lead to OM establishment and severity.

In Vitro Cytological Responses against Laser Photobiomodulation for Periodontal Regeneration

Periodontal disease is a chronic inflammatory disease caused by periodontal bacteria. Recently, periodontal phototherapy, treatment using various types of lasers, has attracted attention. Photobiomodulation, the biological effect of low-power laser irradiation, has been widely studied. Although many types of lasers are applied in periodontal phototherapy, molecular biological effects of laser irradiation on cells in periodontal tissues are unclear. Here, we have summarized the molecular biological effects of diode, Nd:YAG, Er:YAG, Er,Cr:YSGG, and CO₂ lasers irradiation on cells in periodontal tissues. Photobiomodulation by laser irradiation enhanced cell proliferation and calcification in osteoblasts with altering gene expression. Positive effects were observed in fibroblasts on the proliferation, migration, and secretion of chemokines/cytokines. Laser irradiation suppressed gene expression related to inflammation in osteoblasts, fibroblasts, human periodontal ligament cells (hPDLCs), and endothelial cells. Furthermore, recent studies have revealed that laser irradiation affects cell differentiation in hPDLCs and stem cells. Additionally, some studies have also investigated the effects of laser irradiation on endothelial cells, cementoblasts, epithelial cells, osteoclasts, and osteocytes. The appropriate irradiation power was different for each laser apparatus and targeted cells. Thus, through this review, we tried to shed light on basic research that would ultimately lead to clinical application of periodontal phototherapy in the future.

Immunomodulatory activity seen as a result of photobiomodulation therapy in stimulated primary human fibroblasts

OBJECTIVE

Oral biofilms burden host responses by induction of inflammatory mediators, exacerbating periodontal inflammation. Photobiomodulation Therapy (PBMT) has been shown to decrease levels of pro-inflammatory cytokines and chemokines. However, optimal wavelengths and exposure doses have not been established. This study investigated the effects of PBMT on human periodontal ligament fibroblasts (hPDLFs) stimulated with inflammatory mediators (LPS, TNF-α, and IL-1β).

METHODS

Cytotoxic effects of laser wavelengths 660 nm and 810 nm were assessed by measuring their effects on cellular dehydrogenase activity. The study was expanded to include 980 nm, 660 nm + 810 nm, and 810 nm + 980 nm. P.g. LPS, TNF-α, and/or IL-1β were added one hour before irradiation, then exposed to laser irradiation to determine the most appropriate stimulus. The levels of INF-γ, IL-6, IL-8, IL-17A/F, and MCP-1 production in stimulated hPDLFs were measured and analyzed.

RESULTS

P.g. LPS was a poor stimulus for hPDLFs, while TNF-α and IL-1β significantly elevated the analytes. The 660 nm laser treatment induced pro-inflammatory cytokines when stimulated, while 810 nm exhibited significant suppression. IL-1β was the stimulus of choice and the 810 nm wavelength alone exhibited anti-inflammatory effects for all analytes except IL-8, while the 810 nm in combination with 660 nm and/or 980 nm exhibited effects similar to 810 nm alone.

CONCLUSIONS

The downregulation of inflammatory mediators by the combination or individual treatment with 810 nm wavelength shows promise for the management of periodontal inflammation. PBMT may lead to the development of a novel approach in the management of periodontal disease.

In vitro effects of photobiomodulation applied to gingival fibroblasts cultured on titanium and zirconia surfaces and exposed to LPS from Escherichia coli

Photobiomodulation (PBM) therapy is used to stimulate cell proliferation and metabolism, as well as reduce inflammatory cytokine synthesis, which plays a main role in the long-term stability of implants. This study assessed the response of gingival fibroblasts cultured on titanium (Ti) and zirconia (ZrO₂), submitted to PBM and exposed to lipopolysaccharide (LPS). Cells seeded on Ti and ZrO₂ were irradiated (InGaAsP; 780 nm, 25 mW) 3 times, using 0.5, 1.5, and 3.0 J/cm² doses, and exposed to Escherichia coli LPS (1 μg/mL). After 24 h, cell viability (alamarBlue, n = 8), interleukin 6 (IL-6) and 8 (IL-8) synthesis (ELISA, n = 6), and IL-6 and vascular endothelial growth factor (VEGF) gene expression (qPCR, n = 5) were assessed and statistically analyzed (one-way ANOVA, α = 0.05). Cell morphology was evaluated by fluorescence microscopy. Increased cell viability occurred in all groups cultured on Ti compared with that of the control, except for cells exposed to LPS. Fibroblasts cultured on ZrO₂ and LPS-exposed exhibited reduced viability. PBM at 3.0 J/cm² and 1.5 J/cm² downregulated the IL-6 synthesis by fibroblasts seeded on Ti and ZrO₂, as well as IL-8 synthesis by cells seeded on ZrO₂. Fibroblasts seeded on both surfaces and LPS-exposed showed increased IL-6 gene expression; however, this activity was downregulated when fibroblasts were irradiated at 3.0 J/cm². Enhanced VEGF gene expression by cells seeded on Ti and laser-irradiated (3.0 J/cm²). Distinct patterns of cytoskeleton occurred in laser-irradiated cells exposed to LPS. Specific parameters of PBM can biomodulate the inflammatory response of fibroblasts seeded on Ti or ZrO₂ and exposed to LPS.

Current topical trends and novel therapeutic approaches and delivery systems for oral mucositis management

Oral mucositis (OM) is an extremely serious and challenging complication of chemoradiotherapy, which may limit the efficacy of cancer treatment. Complications related to OM include potential nutrition impairment, high economic burden, and negative impacts on patients' quality of life. Current therapeutic options with local traditional pharmaceutical formulations are largely focused on controlling symptoms, and only few agents are available for treatment. Several local supportive and palliative agents are used for the prevention of OM; however, a standard treatment for the disease has not been confirmed yet. The efficacy of treatment could be improved through the introduction of new medical agents with updated dosage forms that can enhance and optimize local drug delivery and create greater therapeutic effects with fewer side effects. The focus of this review was to provide clear and direct information about the currently available topical therapeutic agents in clinical practice used to cure and/or reduce the incidence of ulcerative symptoms of OM, excluding the associated pain and other coexisting complications such as bacterial and fungal infections. The review also provides recent evidences regarding agents that could be used as promising novel therapies in updated local delivering systems. This will support further encouraging options and approaches for the management of OM and will improve compliance that could be translated in better disease control and survival.

Effect of Photobiomodulation on Secretion of IL-6 and IL-8 by Human Gingival Fibroblasts In Vitro

Objective: The aim of this study was to evaluate the effects of 940-nm diode laser irradiation on proinflammatory cytokine secretions [interleukin (IL)-6 and IL-8] by human gingival fibroblasts in vitro. Background: Photobiomodulation has been routinely used in many dental procedures; however, the exact biological action mechanism of photobiomodulation and its therapeutic benefits have not been established. Methods: Cells derived from systemically healthy individuals were treated with three different laser parameters-6 J for 20 sec [0.84 J/cm² (0.04 W/cm²)], 10 J for 20 sec [1.4 J/cm² (0.07 W/cm²)], and 14 J for 20 sec [1.97 J/cm² (0.09 W/cm²)]-in the presence and absence of 1 μg/mL lipopolysaccharide (LPS) stimulation. Laser irradiations were carried out by a 940-nm diode laser device in continuous pain therapy mode with a deep tissue handpiece. Changes in cell viability, cytokine secretions, and mitogen-activated protein kinase pathway expressions were investigated, and results were compared with negative (medium) and positive control (1 μg/mL LPS) groups. The data obtained were statistically analyzed by the Mann-Whitney U test for pairwise comparisons among groups at the 0.05 level of significance. Results: Laser therapy with 0.84-1.4 J/cm² amplified IL-6 and IL-8 secretions, whereas 1.97 J/cm² suppressed IL-6 and IL-8 release in LPS-stimulated cells. Cell viability did not show a variation with photobiomodulation. Conclusions: These results demonstrate that photobiomodulation can alter IL-6 and IL-8 release, with cytokine suppression potency at a relatively high dose, as demonstrated previously. However, in contrast, we found that a low level of stimulation (6 J) in the presence of inflammation (LPS stimulation) may further enhance IL-6 and IL-8 release. We also found that p38 and ERK1/2 pathways are activated by LPS as well as by photobiomodulation.

Photobiomodulation of inflammatory-cytokine-related effects in a 3-D culture model with gingival fibroblasts

The aim of this study was to assess the effects of IL-6 and IL-8 cytokines on human gingival fibroblasts (HGF) cultured in a 3-D model and the possible photobiomodulation (PBM) of such effects by low-level laser therapy. In complete culture medium (DMEM), HGF from a healthy patient were seeded in a type I collagen matrix inserted into 24-well plates. After 5 days of incubation, the cytokines were added or not to serum-free DMEM, which was applied to the cell-enriched matrices. Then, PBM was performed: three consecutive irradiations using LaserTable diode device (780 nm, 0.025 W) at 0.5 J/cm² were delivered or not to the cells. Twenty-four hours after the last irradiation, cell viability and morphology, gene expression, and synthesis of inflammatory cytokines and growth factors were assessed. The histological evaluation demonstrated that, for all groups, matrices presented homogeneous distribution of cells with elongated morphology. However, numerous cytokine-exposed cells were rounded. IL-6 and IL-8 decreased cell viability, synthesis of VEGF, and gene expression of collagen type I. PBM enhanced cell density in the matrices and stimulated VEGF expression, even after IL-6 challenge. Reduced TNF-α synthesis occurred in those cells subjected to PBM. In conclusion, PBM can penetrate collagen matrix and stimulate HGF, highlighting the relevance of this research model for further phototherapy studies and in vitro biomodulation of the healing process.

Low level laser therapy for the patients with painful diabetic peripheral neuropathy - A systematic review

BACKGROUND

Low Level Laser Therapy (LLLT) is an emerging treatment modality for management of neuropathic pain. It works by triggering biochemical changes with in cells.

OBJECTIVE

This systematic review focused on finding evidence on the effectiveness of LLLT on treatment of painful diabetic neuropathy.

METHODS

We conducted a systematic review (PubMed, Web of Science, CINAHL and Cochrane) to find the evidence on effectiveness of LLLT on treatment of painful diabetic neuropathy. Randomized and non-randomized studies were included in the review.

RESULTS

A total of 627 studies were screened. After the exclusion criteria (duplicate, animal studies, LLLT for treating other neuralgias) 6 studies were included in the study. The outcome measure that were considered were the difference in pain score and nerve conduction velocity test and quality of life questionnaire.

CONCLUSION

The evidence obtained shows LLLT has a positive effect in controlling diabetic neuropathic pain.

Under the spotlight: mechanisms of photobiomodulation concentrating on blue and green light

Photobiomodulation (PBM) describes the application of light at wavelengths ranging from 400-1100 nm to promote tissue healing, reduce inflammation and promote analgesia. Traditionally, red and near-infra red (NIR) light have been used therapeutically, however recent studies indicate that other wavelengths within the visible spectrum could prove beneficial including blue and green light. This review aims to evaluate the literature surrounding the potential therapeutic effects of PBM with particular emphasis on the effects of blue and green light. In particular focus is on the possible primary and secondary molecular mechanisms of PBM and also evaluation of the potential effective parameters for application both in vitro and in vivo. Studies have reported that PBM affects an array of molecular targets, including chromophores such as signalling molecules containing flavins and porphyrins as well as components of the electron transport chain. However, secondary mechanisms tend to converge on pathways induced by increases in reactive oxygen species (ROS) production. Systematic evaluation of the literature indicated 72% of publications reported beneficial effects of blue light and 75% reported therapeutic effects of green light. However, of the publications evaluating the effects of green light, reporting of treatment parameters was uneven with 41% failing to report irradiance (mW cm^-2) and 44% failing to report radiant exposure (J cm^-2). This review highlights the potential of PBM to exert broad effects on a range of different chromophores within the body, dependent upon the wavelength of light applied. Emphasis still remains on the need to report exposure and treatment parameters, as this will enable direct comparison between different studies and hence enable the determination of the full potential of PBM.

A brief literature review and own clinical experience in prophylaxis of oral mucositis in children using low level laser therapy

OBJECTIVE

The article describes the experience of clinical application of low level laser therapy in pediatric oncology for the prevention and treatment of chemotherapy complications such as oral mucositis.

BACKGROUND

For this purpose, for the first time in the world non-invasive laser blood illumination is used on the sinocarotid zone (on the projection of the common carotid artery symmetrically) and popliteal fossa in order to stimulate the phagocytic activity of leukocytes.

METHODS

25 children with different oncological diseases were given non-invasive laser blood illumination treatment (904 nm, pulse mode, 100 ns, 50-150 Hz, 5-7 W, 4 cm², 1-2 minutes daily per each procedure) 1-3 days before the beginning of chemotherapy. For the objectification of the results of treatment, the phagocytic activity of leukocytes was evaluated.

RESULTS

None of the children who underwent low level laser therapy course had any complications and no cases of oral mucositis developed.

CONCLUSIONS

Clinical experience has shown high efficacy and safety of low level laser therapy aimed at preventing the development of complications of chemotherapy, primarily oral mucositis, and stimulating the phagocytic activity of leukocytes.

Low incidence of choroidal neovascularization following subthreshold diode micropulse laser (SDM) in high-risk AMD

Purpose

To determine the incidence of new choroidal neovascularization (CNV) in eyes with dry age-related macular degeneration (AMD) following subthreshold diode micropulse laser (SDM).

Method

In an observational retrospective cohort study, the records of all patients active in the electronic medical records database were reviewed to identify eyes with dry AMD treated with SDM. Identified eyes were classified by simplified AREDS categories, and analyzed for the primary endpoint of new CNV after treatment.

Results

The EMR revealed SDM was offered to 373/392 (95%) patients with dry AMD and elected by 363/373 (97%) between 2008–2017. Follow up was available for 354/363 patients (547 eyes, 98%) (range 6–108 mos., avg. 22). CNV risk factors included age (median 84 years, 67% > 80); reticular pseudodrusen (214 eyes, 39%); AREDS category (78% category 3 and 4); and fellow eye CNV (128 eyes, 23%). New CNV developed in 9/547 eyes (1.6%, annualized rate 0.87%). Visual acuity was unchanged. There were no adverse treatment effects.

Summary

In a review of a large group of eyes with exceptionally high-risk AMD, SDM was followed by a very low incidence of new CNV. If confirmed by further study, SDM would offer a new and highly effective treatment to reduce the risk of vision loss from AMD.

Text mining-based in silico drug discovery in oral mucositis caused by high-dose cancer therapy

INTRODUCTION

Oral mucositis (OM) is a major dose-limiting side effect of chemotherapy and radiation used in cancer treatment. Due to the complex nature of OM, currently available drug-based treatments are of limited efficacy.

OBJECTIVES

Our objectives were (i) to determine genes and molecular pathways associated with OM and wound healing using computational tools and publicly available data and (ii) to identify drugs formulated for topical use targeting the relevant OM molecular pathways.

METHODS

OM and wound healing-associated genes were determined by text mining, and the intersection of the two gene sets was selected for gene ontology analysis using the GeneCodis program. Protein interaction network analysis was performed using STRING-db. Enriched gene sets belonging to the identified pathways were queried against the Drug-Gene Interaction database to find drug candidates for topical use in OM.

RESULTS

Our analysis identified 447 genes common to both the "OM" and "wound healing" text mining concepts. Gene enrichment analysis yielded 20 genes representing six pathways and targetable by a total of 32 drugs which could possibly be formulated for topical application. A manual search on ClinicalTrials.gov confirmed no relevant pathway/drug candidate had been overlooked. Twenty-five of the 32 drugs can directly affect the PTGS2 (COX-2) pathway, the pathway that has been targeted in previous clinical trials with limited success.

CONCLUSIONS

Drug discovery using in silico text mining and pathway analysis tools can facilitate the identification of existing drugs that have the potential of topical administration to improve OM treatment.

Improved retinal and visual function following panmacular subthreshold diode micropulse laser for retinitis pigmentosa

Objectives

To examine the effect of subthreshold diode micropulse laser (SDM) on pattern electroretinography (PERG) and visual function in retinitis pigmentosa (RP).

Methods

The records of all patients (pts) undergoing SDM in a vitreoretinal subspecialty practice were reviewed. Inclusion criteria included the presence of RP evaluated before and after SDM by PERG. As a secondary outcome measure, the results of automated omnifield resolution perimetry (ORP) were also reviewed.

Results

All eyes undergoing SDM for RP were eligible study, including 26 eyes of 15 pts; seven male and eight female, aged 16–69 (avg. 47) years. Retinal function by PERG improved by all indices, with significant improvements in the 24° field signal latency measures; the MagD(µV)/ Mag(µV) ratio (P < 0.0001) and the MagD(µV) amplitude (P = 0.0003). ORP significantly improved by all indices (p = 0.02–0.002). Average best-corrected chart visual acuities improved from 0.6 to 0.4 logMAR units (p = 0.02). There were no adverse treatment effects.

Conclusions

SDM significantly improved chart visual acuity, mesopic logMAR visual acuity perimetry, and retinal function by PERG in RP without adverse treatment effects. Treatment responses indicate a significant capacity for rescue of dysfunctional retina. These results suggest that early and periodic treatment with SDM might slow disease progression and reduce long-term vision loss.

Epithelial cell-enhanced metabolism by low-level laser therapy and epidermal growth factor

Reepithelialization and wound closure are the desired outcome for several ulcerative conditions. Such resolution reduces the possibility of wound contamination and maintenance of the injury and improves the reestablishment of tissue morphology and functions. Investigators are seeking adjuvant therapies that can accelerate wound healing and are developing new strategies for clinical applications. This study compared the effects of epidermal growth factor (EGF) application and low-level laser therapy (LLLT) on cultured epithelial cells. Cells were seeded in 24-well plates. After a 24-h incubation, the epithelial cells were either treated with EGF (100 μM in serum-free DMEM for 72 h) or subjected to LLLT (780 nm, 25 mW, 0.5, 1.5, and 3 J/cm²) by three applications every 24 h. Seventy-two hours after cells were treated with EGF or LLLT, cell migration, viability, proliferation, and collagen synthesis were assessed. Cells treated with EGF showed increased cell viability, proliferation, and collagen synthesis compared with those cells that received no treatment. LLLT enhanced cell migration; however, no significant effects of laser irradiation on other cell functions were observed. Comparison of both therapies demonstrated that EGF and LLLT enhanced specific epithelial cell activities related to wound healing.

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.

Effects of low-level laser therapy and epidermal growth factor on the activities of gingival fibroblasts obtained from young or elderly individuals

This study evaluated the effects of low-level laser therapy (LLLT) and epidermal growth factor (EGF) on fibroblasts obtained from young and elderly individuals. Gingival fibroblasts from young (Y) and elderly (E) individuals were seeded in wells of 24-well plates with Dulbecco's modified Eagle's medium (DMEM) containing 10 % of fetal bovine serum (FBS). After 24 h, the cells were irradiated (LASERTable-InGaAsP-780 ± 3 nm, 25 mW, 3 J/cm²) or exposed to EGF (100 μM). After 72 h, cells were evaluated for viability, migration, collagen and vascular endothelial growth factor (VEGF) synthesis, and gene expression of growth factors. Data were analyzed by Kruskal-Wallis and Mann-Whitney tests (α = 5 %). Y and E fibroblasts irradiated with laser or exposed to EGF showed increased viability and collagen synthesis. Enhanced cell migration was observed for Y fibroblasts after both treatments, whereas only the LLLT stimulated migration of E cells. VEGF synthesis was higher for Y and E cells exposed to EGF, while this synthesis was reduced when E fibroblasts were irradiated. Increased gene expression of VEGF was observed only for Y and E fibroblasts treated with LLLT. Regardless of a patient's age, the LLLT and EGF applications can biostimulate gingival fibroblast functions involved in tissue repair.

Effect of Photobiomodulation on Transforming Growth Factor-β1, Platelet-Derived Growth Factor-BB, and Interleukin-8 Release in Palatal Wounds After Free Gingival Graft Harvesting: A Randomized Clinical Study

Objective: This study evaluated the impact of photobiomodulation (PBM) on the healing of the donor palatal area following free gingival graft (FGG) harvesting by examining changes in transforming growth factor (TGF)-β₁, platelet-derived growth factor (PDGF)-BB, and interleukin (IL)-8 levels in palatal wound fluid (PWF). Material and methods: Thirty patients were selected and randomly assigned to receive PBM (laser group) or PBM sham (sham group) in the palatine area after FGG harvesting. A neodymium-doped yttrium aluminum garnet (Nd:YAG) laser (1064 nm) was applied to the test sites immediately after surgery and every 24 h thereafter for 4 days. PWF was collected on Days 7 and 12, and PWF TGF-β₁, PDGF-BB, and IL-8 levels were analyzed by enzyme-linked immunosorbent assays (ELISA). Results: PWF TGF-β₁, PDGF-BB, and IL-8 levels were significantly lower on Day 12 than on Day 7 for both groups. PWF TGF-β₁, PDGF-BB, and IL-8 levels of the laser group were significantly higher than those of sham group on Day 7 (p < 0.05). PWF TGF-β₁ levels were also significantly higher in laser group than in the sham group on Day 12; however, differences in PDGF-BB and IL-8 levels between groups on Day 12 were statistically nonsignificant. Conclusions: Observed increases in PWF TGF-β₁, PDGF-BB, and IL-8 levels suggest that PBM may accelerate wound healing by stimulating production of selected mediators.