Inflammatory cytokines are suppressed by light-emitting diode irradiation of P. gingivalis LPS-treated human gingival fibroblasts: Inflammatory cytokine changes by LED irradiation

Evaluation of the use of chamomile in isolation and in association with laser photobiomodulation in the healing of rats oral mucosa

Laser photobiomodulation (LPBM) has been shown to be one of the possible modulating agents of inflammation. Similarly, medicinal plants, such as chamomile (Matricaria recutita) are also used with the same purpose. To evaluate tissue repair in the dorsum of the tongue of rats under topical use of chamomile alone and in association with LPBM. Seventy-five male Wistar rats received a standardized wound on the dorsum of the tongue and were allocated into experimental groups: Control (G1), Chamomile Fluid extract (G2), Chamomile Infusion (G3), Laser (G4), Chamomile Infusion + Laser (G5). Euthanasia was done on days 3, 7, and 14 after surgery. Ulcers were evaluated and measured with a caliper. Sections stained with hematoxylin and eosin and Picrosirius Red allowed evaluation of edema, inflammatory infiltrate, cellularity, and re-epithelialization and characterization of total collagen. Histomorphometric analysis of the percentage of total collagen, the distance from the basal layer to the epithelial surface, and the thickness of the stratum corneum were performed. The G2 and G4 groups modulated the exudative and proliferative phases of inflammation, both clinically and histologically. The G3 and G5 groups did not show significant differences in relation to the G1 group in most of the evaluated parameters. Chamomile fluid extract and LPBM alone showed better clinical and histological responses for tissue repair than the association between these therapeutic modalities. There were differences in the parameters of clinical, histological, and histomorphometric patterns between the experimental groups of the present investigation. The LPBM proved to be superior in the performed analysis.

Antiviral and synergistic effects of photo-energy with acyclovir on herpes simplex virus type 1 infection

This experimental study aimed to evaluate the antiviral and synergistic effects of photoenergy irradiation on human herpes simplex virus type I (HSV-1) infection. We assessed viral replication, plaque formation, and relevant viral gene expression to examine the antiviral and synergistic effects of blue light (BL) with acyclovir treatment. Our results showed that daily BL (10 J/cm2) irradiation inhibited plaque-forming ability and decreased viral copy numbers in HSV-1-infected monkey kidney epithelial Vero cells and primary human oral keratinocyte (HOK) cells. Combined treatment with the antiviral agent acyclovir and BL irradiation increased anti-viral activity, reducing viral titers and copy numbers. In particular, accumulated BL irradiation suppressed characteristic viral genes including UL19 and US6, and viral DNA replication-essential genes including UL9, UL30, UL42, and UL52 in HOK cells. Our results suggest that BL irradiation has anti-viral and synergistic properties, making it a promising therapeutic candidate for suppressing viral infections in clinical trials.

Photobiomodulation Controls Keratinocytes Inflammatory Response through Nrf2 and Reduces Langerhans Cells Activation

Photobiomodulation (PBM) is rapidly gaining traction as a valuable tool in dermatology for treating many inflammatory skin conditions using low levels of visible light or near-infrared radiation. However, the physiological regulatory pathways responsible for the anti-inflammatory effect of PBM have not been well defined. Since previous studies showed that nuclear factor-erythroid 2 like 2 (Nrf2) is a master regulator of the skin inflammatory response, we have addressed its role in controlling inflammation by PBM. Primary human keratinocytes (KCs) stimulated with 2,4-dinitrochlorobenzene (DNCB) to mimic pro-inflammatory stress were illuminated with two wavelengths: 660 nm or 520 nm. Both lights significantly reduced the mRNA expression of the DNCB-triggered TNF-α, IL-6, and IL-8 cytokines in KCs, while they enhanced Nrf2 pathway activation. PBM-induced Nrf2 is a key regulator of the inflammatory response in KCs since its absence abolished the regulatory effect of light on cytokines production. Further investigations of the mechanisms contributing to the immunoregulatory effect of PBM in inflamed human skin explants showed that 660 nm light prevented Langerhans cells migration into the dermis, preserving their dendricity, and decreased pro-inflammatory cytokine production compared to the DNCB-treated group. This study is the first to report that the PBM-mediated anti-inflammatory response in KCs is Nrf2-dependent and further support the role of PBM in skin immunomodulation. Therefore, PBM should be considered a promising alternative or complementary therapeutic approach for treating skin-related inflammatory diseases.

Blue light irradiation exerts anti-viral and anti-inflammatory properties against herpes simplex virus type 1 infection

The aim of this study was to investigate the antiviral and anti-inflammatory functions of blue light (BL) in cutaneous viral infections. Previously, we examined the photo-biogoverning role of 450 nm BL in SARS-CoV-2-infected cells, which showed that photo-energy could inhibit viral activation depending on the number of photons. However, the communication network between photo-energy irradiation and immune cells involved in viral infections has not been clarified. We verified viral activation, inflammatory responses, and relevant downstream cascades caused by human simplex virus type I (HSV-1) after BL irradiation. To examine the antiviral effect of BL, we further tested whether BL could disturb viral absorption or entry into host cells. The results showed that BL irradiation, but not green light (GL) exposure, specifically decreased plaque-forming activity and viral copy numbers in HSV-1-infected cells. Accumulated BL irradiation inhibited the localization of viral proteins and the RNA expression of characteristic viral genes such as UL19, UL27, and US6, thus exerting to an anti-viral effect. The results also showed that BL exposure during viral absorption interfered with viral entry or destroyed the virus, as assessed by plaque formation and quantitative PCR assays. The levels of the pro-inflammatory mediators interleukin (IL)-18 and IL-1β in M1-polarized macrophages were increased by HSV-1 infection. However, these increases were attenuated by BL irradiation. Importantly, BL irradiation decreased cGAS and STING expression, as well as downstream NF-κB p65, in M1-polarized HSV-1-infected macrophages, demonstrating anti-viral and anti-inflammatory properties. These findings suggest that BL could serve as an anti-viral and anti-inflammatory therapeutic candidate to treat HSV-1 infections.

Dual red and near-infrared light-emitting diode irradiation ameliorates LPS-induced otitis media in a rat model

Objective: Otitis media (OM) is an infectious and inflammatory disease of the middle ear (ME) that often recurs and requires long-term antibiotic treatment. Light emitting diode (LED)-based devices have shown therapeutic efficacy in reducing inflammation. This study aimed to investigate the anti-inflammatory effects of red and near-infrared (NIR) LED irradiation on lipopolysaccharide (LPS)-induced OM in rats, human middle ear epithelial cells (HMEECs), and murine macrophage cells (RAW 264.7). Methods: An animal model was established by LPS injection (2.0 mg/mL) into the ME of rats via the tympanic membrane. A red/NIR LED system was used to irradiate the rats (655/842 nm, intensity: 102 mW/m², time: 30 min/day for 3 days and cells (653/842 nm, intensity: 49.4 mW/m², time: 3 h) after LPS exposure. Hematoxylin and eosin staining was performed to examine pathomorphological changes in the tympanic cavity of the ME of the rats. Enzyme-linked immunosorbent assay, immunoblotting, and RT-qPCR analyses were used to determine the mRNA and protein expression levels of interleukin-1β (IL-1β), IL-6, and tumor necrosis factor-α (TNF-α). Mitogen-activated protein kinases (MAPKs) signaling was examined to elucidate the molecular mechanism underlying the reduction of LPS-induced pro-inflammatory cytokines following LED irradiation. Results: The ME mucosal thickness and inflammatory cell deposits were increased by LPS injection, which were reduced by LED irradiation. The protein expression levels of IL-1β, IL-6, and TNF-α were significantly reduced in the LED-irradiated OM group. LED irradiation strongly inhibited the production of LPS-stimulated IL-1β, IL-6, and TNF-α in HMEECs and RAW 264.7 cells without cytotoxicity in vitro. Furthermore, the phosphorylation of ERK, p38, and JNK was inhibited by LED irradiation. Conclusion: This study demonstrated that red/NIR LED irradiation effectively suppressed inflammation caused by OM. Moreover, red/NIR LED irradiation reduced pro-inflammatory cytokine production in HMEECs and RAW 264.7 cells through the blockade of MAPK signaling.

Porphyromonas gingivalis Gingipains Induce Cyclooxygenase-2 Expression and Prostaglandin E2 Production via ERK1/2-Activated AP-1 (c-Jun/c-Fos) and IKK/NF-κB p65 Cascades

Porphyromonas gingivalis is commonly known as one of the major pathogens contributing to periodontitis, and its persistent infection may increase the risk for the disease. The proinflammatory mediators, including IL-6, TNF-α, and cyclooxygenase-2 (COX-2)/PGE₂, are closely associated with progression of periodontitis. In this study, we focused on the cysteine protease "gingipains," lysine-specific gingipain, arginine-specific gingipain (Rgp) A, and RgpB, produced by P. gingivalis, and used the wild-type strain and several gene-deletion mutants (rgpA, rgpB, kgp, and fimA) to elucidate the involvement of gingipains in COX-2 expression and PGE₂ production. We infected human monocytes, which are THP-1 cells and primary monocytes, with these bacterial strains and found that gingipains were involved in induction of COX-2 expression and PGE₂ production. We have shown that the protease activity of gingipains was crucial for these events by using gingipain inhibitors. Furthermore, activation of ERK1/2 and IκB kinase was required for gingipain-induced COX-2 expression/PGE₂ production, and these kinases activated two transcription factors, c-Jun/c-Fos (AP-1) and NF-κB p65, respectively. In particular, these data suggest that gingipain-induced c-Fos expression via ERK is essential for AP-1 formation with c-Jun, and activation of AP-1 and NF-κB p65 plays a central role in COX-2 expression/PGE₂ production. Thus, we show the (to our knowledge) novel finding that gingipains with the protease activity from P. gingivalis induce COX-2 expression and PGE₂ production via activation of MEK/ERK/AP-1 and IκB kinase/NF-κB p65 in human monocytes. Hence it is likely that gingipains closely contribute to the inflammation of periodontal tissues.

Evaluation of Photobiogoverning Role of Blue Light Irradiation on Viral Replication

Most recently, severe acute respiratory syndrome coronavirus-2 has triggered a global pandemic without successful therapeutics. The goal of the present study was to define the antiviral effect and therapeutic action of blue light irradiation in SARS-CoV-2-infected cells. Vero cells were infected with SARS-CoV-2 (NCCP43326) or mock inoculum at 50 pfu/well. After blue light irradiation, the inhibitory effect was assessed by qPCR and plaque reduction assay. When Vero cells were irradiated to blue light ranging from 1.6 to 10 J cm^-2 , SARS-CoV-2 replication was inhibited by up to 80%. The antiviral effect of blue light irradiation was associated with translation suppression via the phosphorylation of eIF2α by prolonging endoplasmic reticulum (ER) stress. The levels of LC3A/B and Beclin-1, which are key markers of autophagy, and the levels of PERK and PDI for ER stress were highly increased, whereas caspase-3 cleavage was inhibited after blue light irradiation in the later stage of infection. Our data revealed that blue light irradiation exerted antiviral and photo-biogoverning activities by prolonging ER stress and stimulating autophagy progression during viral infection. The findings increase our understanding of how photo-energy acts on viral progression and have implications for use in therapeutic strategies against COVID-19.

Role of E2F1/SPHK1 and HSP27 During Irradiation in a PMA-Induced Inflammatory Model

Background: Sphingosine kinase 1 (SPHK1) and heat shock protein 27 (HSP27) are important for antioxidant and anti-inflammatory effects after red light irradiation in an inflammatory model. Objective: The purpose of the present study was to evaluate whether SPHK1 and HSP27 work independently or are dependent on some other regulator after 625 nm light-emitting diode irradiation in the human keratinocyte (HaCaT) cell line. Methods: Differentially expressed genes (DEGs) were identified between groups with or without 625 nm photobiomodulation (PBM) in the inflammatory model. Potential transcription factors (TFs) of key DEGs were predicted using the iRegulon plugin. The mechanism was investigated by analyzing mRNA and protein expression levels, prostaglandin E2 levels, and intracellular reactive oxygen species (ROS) in phorbol 12-myristate 13-acetate (PMA)-induced HaCaT cells after 625 nm PBM. Results: A total of 6 TFs (e.g., E2F1) and 51 key DEGs (e.g., SPHK1) were identified after 625 nm PBM in PMA-stimulated HaCaT cells. E2F1 worked as a regulator of SPHK1; however, it did not affect HSP27. E2F1 knockdown drastically decreased the SPHK1 expression level and increased the intracellular ROS, as well as the expression levels of inflammation-related proteins in PMA-induced HaCaT cells. In addition, the inhibition of HSP27 decreased the anti-inflammatory effect of 625 nm PBM. Conclusions: E2F1 worked as a TF of SPHK1 and exhibited anti-inflammatory and antioxidative effects through SPHK1 in PMA-induced HaCaT cells after 625 nm PBM. HSP27 is essential for the 625 nm PBM-induced anti-inflammatory function. Therefore, E2F1/SPHK1 and HSP27 could be used as potential biomarkers for anti-inflammatory therapy with 625 nm PBM.

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.

Immunomodulatory effects of Nd:YAG (1064 nm) and diode laser (810 nm) wavelengths to LPS-challenged human gingival fibroblasts

OBJECTIVE

Human gingival fibroblasts (hGFs) are involved in inflammatory responses to bacteria by recognizing pathogen-associated molecular patterns. In search of host modulation strategies to increase LPS tolerance, Low level laser therapy (LLLT) has been suggested as an alternative treatment that reduces periodontal tissue inflammation. In this study, we investigate whether 810 nm (diode) and 1064 nm (Nd:YAG) laser wavelengths, modulate pro-inflammatory responses to LPS challenges in hGFs.

DESIGN

Primary hGFs were challenged with Porphyromonas gingivalis LPS and irradiated with either Diode (810 nm) or with Nd:YAG (1064 nm) lasers. Cell cultures were examined for cell proliferation by MTT assay and IL-6 and IL-8 expression by qPCR at 24, 48 and 72 h. IL-6 and IL-8 protein levels were detected via ELISA.

RESULTS

Naïve hGF populations irradiated with both Diode 810 nm and Nd:YAG 1064 nm lasers demonstrated cellular proliferation (p < 0.05), but LLLT did not affect cellular viability in LPS-challenged cells. IL-6 and IL-8 gene expression levels revealed significant anti-inflammatory effects of irradiation with both examined wavelengths on hGFs challenged with P. gingivalis LPS. Protein levels of these cytokines were increased by LPS challenge. Treatment with LLLT inhibited this increase for both wavelengths evaluated in the study at a statistically significant level particularly for the first 48 h.

CONCLUSIONS

The present study demonstrates a modulatory effect of LLLT using both 810 nm diode and Nd:YAG 1064 nm lasers in gingival fibroblasts by decreasing the production of IL-6, IL-8 in response to LPS.

The inflammation and reactive oxygen species regulated by Nrf2 and NF-κB signaling pathways in 630-nm light-emitting diode irradiation treated THP-1 monocytes/macrophages

Because of a large number of macrophages and its secreted pro-inflammatory factors in the synovial fluid of patients with rheumatoid arthritis, the present study aimed to investigate the effect and mechanism of 630-nm LED exposure on monocytes/macrophages and its anti-inflammatory effect. The THP-1 monocytes and PMA-induced THP-1 macrophages (THP-1 macrophages) were employed and irradiated by 630-nm LED for different time and times, and then measure the pro-inflammatory cytokines production by RT-qPCR and Milliplex MAP Multiplex assay, the proteins involved in inflammation pathway and reactive oxygen species (ROS) levels in the cells were detected by Western blot and DCFH-DA method. The exposure dose of red LED (15.3 J/cm², 30.6 J/cm²) were determined as no-influence on the cell proliferation, the pro-inflammatory factors TNF-α and IL-1β mRNAs, and secretions in supernatant of THP-1 macrophages were significantly decreased after LED exposure. The ROS production was blocked in THP-1 monocytes and THP-1 macrophages after treatment of LED. Finally, the phosphorylated NF-κB proteins which involved in inflammation pathway significantly decreased, and its inhibitors Nrf2 were slightly upregulated. The effects of LED anti-inflammation response are dependent on the mechanism of inhibiting ROS level and regulating NF-κB signaling pathways by increasing Nrf2 expression in the cells. It is suggested that 630-nm LED could decrease pro-inflammation in immune cells, and it may be a beneficial adjunct therapy in relieving inflammation of patients with rheumatoid arthritis.

Photobiomodulation Dose Parameters in Dentistry: A Systematic Review and Meta-Analysis

Objective: This systematic review and meta-analysis of published randomized controlled trials examines a possible relationship between optical spot size at surface tissue, irradiance, radiant exposure, total energy delivered, operator technique and reported clinical outcomes. Background: Clinical photobiomodulation (PBM) therapy has achieved a high level of evidence-based acceptance in the mitigation of oral mucositis associated with cancer radiotherapy and chemotherapy, and supportive clinical research in relation to orthodontic tooth movement, oral medical conditions, including burning mouth syndrome, xerostomia and lichen planus. Inconsistent outcomes have been reported not withstanding a substantial body of primary supportive research from clinical, in vitro and animal studies. Materials and Methods: PubMed, Cochrane Database of Reviews and Google Scholar search engines were applied to identify human clinical trials of PBM therapy in clinical dentistry. A total of 766 articles between February 2009 and June 2020 were identified and following a full text evaluation, 38 papers with sufficient data to permit analyses are included in this investigation. Results: Following a detailed assessment of potential factors that may have an influence in clinical outcome, a clear trend is apparent associating optical spot size to a positive or negative effect. Furthermore, there is a clear difference in the reported results in relation to total energy applied, delivery techniques and optical parameters, which merits further investigation. Factorial statistical analyses identified an association between smaller optical surface applications and an overall lower level of reported clinical success in treating superficial and deeper targets, and correspondingly sub-surface larger target tissues were found to be more responsive to therapy by use of a larger optical surface spot size. Moreover, use of multiple small diameter probe applications was found to provide inconsistent results. Conclusions: Many factors can confound clinical success including variations in anatomy, site location, clinical condition and subject individuality. To achieve higher levels of predictable outcome, a mature appreciation of these factors, plus an expanded understanding of laser parametry, tissue volume and target depth to deliver an adequate dose within current recommended guidelines, is essential.

Phototherapy as a Rational Antioxidant Treatment Modality in COVID-19 Management; New Concept and Strategic Approach: Critical Review

The COVID-19 pandemic has taken the entire globe by storm. The pathogenesis of this virus has shown a cytokine storm release, which contributes to critical or severe multi-organ failure. Currently the ultimate treatment is palliative; however, many modalities have been introduced with effective or minimal outcomes. Meanwhile, enormous efforts are ongoing to produce safe vaccines and therapies. Phototherapy has a wide range of clinical applications against various maladies. This necessitates the exploration of the role of phototherapy, if any, for COVID-19. This critical review was conducted to understand COVID-19 disease and highlights the prevailing facts that link phototherapy utilisation as a potential treatment modality for SARS-CoV-2 viral infection. The results demonstrated phototherapy's efficacy in regulating cytokines and inflammatory mediators, increasing angiogenesis and enhancing healing in chronic pulmonary inflammatory diseases. In conclusion, this review answered the following research question. Which molecular and cellular mechanisms of action of phototherapy have demonstrated great potential in enhancing the immune response and reducing host-viral interaction in COVID-19 patients? Therefore, phototherapy is a promising treatment modality, which needs to be validated further for COVID-19 by robust and rigorous randomised, double blind, placebo-controlled, clinical trials to evaluate its impartial outcomes and safety.

Photobiomodulation and Oral Mucositis: A Systematic Review

Oral mucositis (OM) is a debilitating complication of chemotherapy, and head and neck radiotherapy. In an effort to offer the best possible advice within the limitations of published research, a systematic review with an extended discussion and commentary on dosimetry and dose delivery is presented. Using keywords as listed, Pubmed, Google Scholar and Cochrane databases were searched during a period extending from 1995 to 2019. A total of 782 abstracts were identified. A total of 50 papers were analysed, and of these, 29 satisfied criteria required for systematic review in accordance with an optimized PRISMA statement. Clinical outcome as reported was subject to analysis with respect to time of intervention, incidence and severity of oral mucositis, and pain amelioration, and a comprehensive combined univariate and multivariate statistical analysis of the methods employed was performed. Recommendations are made with respect to the timing of the intervention. Moreover, there is an extended discussion available on the treatment care rationale of photobiomodulation (PBM), and its adjunctive association with OM. In conclusion, early prophylactic application offers clear advantages in clinical management. The many studies and associated variables and covariables assessed here revealed a choice of delivery techniques, associated wavelengths and many further indices to consider with regard to the accomplishment of optical parameters. It is therefore our recommendation that clinicians use PBM as a therapy with a full and proper understanding and training in order to optimise the clinical effects achievable.

Effects of photobiomodulation on annulus fibrosus cells derived from degenerative disc disease patients exposed to microvascular endothelial cells conditioned medium

Intervertebral disc (IVD) degeneration with chronic low back pain is associated with neo-vascularisation into the deeper IVD regions. During this process, endothelial cells (ECs), which are primarily responsible for angiogenesis, interact with the adjacent annulus fibrosus (AF) cells, which are the first line of defence against the invasion of vascular structures into deeper IVD regions. However, the accumulation of inflammatory and catabolic enzymes that results from this interaction promotes matrix degradation and an inflammatory response. Thus, regulating the production of these mediators and catabolic enzymes could ameliorate IVD degeneration. Photobiomodulation (PBM) therapy is a non-invasive stimulation known to have biologically beneficial effects on wound healing, tissue repair, and inflammation. Here, we examined the effects of PBM, administered at various wavelengths (645, 525, and 465 nm) and doses (16, 32, and 64 J/cm²), on EC-stimulated human AF cells. Our results show that PBM selectively inhibited the EC-mediated production of inflammatory mediators, catabolic enzymes, and neurotrophins by human AF cells in a dose- and wavelength-dependent manner. These results suggest that PBM could be a superior and advanced treatment strategy for IVD degeneration.

Inhibitory effect of red LED irradiation on fibroblasts and co-culture of adipose-derived mesenchymal stem cells

The objective of this study was to evaluate the effects of red Light Emiting Diode (red LED) irradiation on fibroblasts in adipose-derived mesenchymal stem cells (ASC) co-culture on the scratch assay. We hypothesized that red LED irradiation could stimulate paracrine secretion of ASC, contributing to the activation of genes and molecules involved in cell migration and tissue repair. ASC were co-cultured with NIH/3T3 fibroblasts through direct contact and subjected to red LED irradiation (1.45 J/cm²/5min6s) after the scratch assay, during 4 days. Four groups were established: fibroblasts (F), fibroblasts + LED (FL), fibroblasts + ASC (FC) and fibroblasts + LED + ASC (FLC). The analyzes were based on Ctgf and Reck expression, quantification of collagen types I and III, tenomodulin, VEGF, TGF-β1, MMP-2 and MMP-9, as well as viability analysis and cell migration. Higher Ctgf expression was observed in FC compared to F. Group FC presented higher amount of tenomodulin and VEGF in relation to the other groups. In the cell migration analysis, a higher number of cells was observed in the scratched area of the FC group on the 4^th day. There were no differences between groups considering cell viability, Reck expression, amount of collagen types I and III, MMP-2 and TGF-β1, whereas TGF-β1 was not detected in the FC group and the MMP-9 in none of the groups. Our hypothesis was not supported by the results because the red LED irradiation decreased the healing response of ASC. An inhibitory effect of the LED irradiation associated with ASC co-culture was observed with reduction of the amount of TGF-β1, VEGF and tenomodulin, possibly involved in the reduced cell migration. In turn, the ASC alone seem to have modulated fibroblast behavior by increasing Ctgf, VEGF and tenomodulin, leading to greater cell migration. In conclusion, red LED and ASC therapy can have independent effects on fibroblast wound healing, but the combination of both does not have a synergistic effect. Therefore, future studies with other parameters of red LED associated with ASC should be tested aiming clinical application for tissue repair.

Conditioned media from blue light-emitting diode-exposed fibroblasts have an anti-inflammatory effect in vitro

We have previously reported the protective effects of blue light-emitting diode (BLED)-stimulated cell metabolites on cell injury. To further examine the effect of conditioned media (CM) derived from BLED (5 J/cm²)-exposed human normal fibroblasts (CMBL5) for clinical application, we have used the choline chloride and phenol red-free media and then concentrated CMBL5 using a centrifugal filter unit. The collected CMBL5-lower part (CMBL5-LO) has evaluated the inflammatory protein expression profile in LPS-stimulated RAW264.7 cells. Comprehensive metabolomic profiling of CMBL5-LO was carried out using hybrid tandem mass spectrometry. Treatment with CMBL5-LO showed the cytoprotective effect on apoptotic cell death, but rather increased apoptotic cells after treatment with CMBL5-upper part (CMBL5-UP). In addition, CMBL5-LO inhibited several chemo-attractants, including interleukin (IL)-6, macrophage inflammatory protein (MIP)-2, chemokine (C-C motif) ligand 5 (CCL5), granulocyte colony-stimulating factor (GCSF), and monocyte chemoattractant protein-1 (MCP-1) expression. Pro-inflammatory nitric oxide was decreased after CMBL5-LO treatment, but not by CMBL5-UP treatment. Interestingly, treatment with CMBL5-LO stimulated expression of heme oxygenase-1, indicating its anti-inflammatory property. Most endoplasmic reticulum (ER) stress proteins except for transcription factor C/EBP homologous protein (CHOP) were highly expressed after irradiation with BLED in cells. Further studies are needed to examine the precise mechanism by CMBL5-LO in cells.

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.

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.

Light-emitting diode therapy protects against ventricular arrhythmias by neuro-immune modulation in myocardial ischemia and reperfusion rat model

Background

Sympathetic overactivation and inflammation are two major mediators to post-myocardial ischemia-reperfusion (I/R)-induced ventricular arrhythmia (VA). The vicious cycle between microglia and sympathetic activation plays an important role in sympathetic hyperactivity related to cardiovascular diseases. Recently, studies have shown that microglial activation might be attenuated by light-emitting diode (LED) therapy. Therefore, we hypothesized that LED therapy might protect against myocardial I/R-induced VAs by attenuating microglial and sympathetic activation.

Methods

Thirty-six male anesthetized rats were randomized into four groups: control group (n = 6), LED group (n = 6), I/R group (n = 12), and LED+I/R group (n = 12). I/R was generated by left anterior descending artery occlusion for 30 min followed by 3 h reperfusion. ECG and left stellate ganglion (LSG) neural activity were recorded continuously. After 3 h reperfusion, a programmed stimulation protocol was conducted to test the inducibility of VA. Furthermore, we extracted the brain tissue to examine the microglial activation, and the peri-ischemic myocardium to examine the expression of NGF and inflammatory cytokines (IL-1β, IL-18, IL-6, and TNF-α).

Results

As compared to the I/R group, LED illumination significantly inhibited the LSG neural activity (P < 0.01) and reduced the inducibility of VAs (arrhythmia score 4.417 ± 0.358 vs. 3 ± 0.3257, P < 0.01) in the LED+I/R group. Furthermore, LED significantly attenuated microglial activation and downregulated the expression of inflammatory cytokines and NGF in the peri-infarct myocardium.

Conclusions

LED therapy may protect against myocardial I/R-induced VAs by central and peripheral neuro-immune regulation.

Hypericin-glucamine antimicrobial photodynamic therapy in the progression of experimentally induced periodontal disease in rats

OBJECTIVE

To evaluate the effect of antimicrobial photodynamic therapy (aPDT) using the photosensitizer hypericin-glucamine in the progression of experimentally induced periodontal disease (PD) in rats.

MATERIAL AND METHODS

Subgingival ligatures were inserted around the upper second molars of 30 rats. After 7 days (Baseline), the animals were randomly distributed into 3 experimental (n = 5) groups: Hypericin-glucamine; LED (amber LED, 700 mA, 590 nm, 90 mW, 34.10 J/cm²); and aPDT (Hypericin-glucamine + LED). The treated hemimaxillae were randomly chosen. The periodontal disease progression was monitored without treatment interference in the opposite hemimaxillaes, which were used as the negative control of each animal. The euthanasia was programmed according to each experimental period, 7 or 15 days after the Baseline. Microtomographic, histometric and Tartrate Resistant Acid Phosphatase (TRAP) immunohistochemistry analyses were carried out.

RESULTS

Computerized microtomography analyses indicated that the aPDT group had a significantly higher percentage of bone tissue when compared to the other 7 days experimental groups. This result was corroborated by the histometric evaluations of the furcal area. The LED-treated group presented the highest percentages of bone volume for the 15 days experimental groups, which is remarkably higher than the groups treated with Hy-g and aPDT. The histometric analyses demonstrated the control groups had greater bone loss in the proximal regions when compared to the treated groups. The aPDT led to a lower osteoclast activity at both 7 and 15 days. Thus, we can conclude that aPDT exhibits positive effects in PD treatment by promoting favorable conditions for periodontal repair.

Protective Effect of BLED-exposed Conditioned Media on Cell Injury

Previous studies have reported that 450 nm blue light emitting diode (BLED) induces apoptosis through a mitochondria-mediated pathway in cancer cells and reduces the early stage tumor growth. This study was performed to determine the effects of BLED-irradiated cell metabolites on cell injury. Our results showed that conditioned medium (CM) from cells irradiated with low-dose BLED (LCM) inhibited apoptosis and increased cell survival. Cell protection-related proteins were identified in cell metabolites of CM and LCM using 2-DE and MALDI-TOF analysis. Treatment with LCM inhibited apoptotic cell death and increased the live cell population. The cellular protective effect of LCM was associated with keratin and collagen type VI secretion from cells after low dose of BLED irradiation. Interestingly, expression of endoplasmic reticulum stress proteins was dose dependently increased after 4 h BLED irradiation. Only levels of BiP, CHOP and ERO1-Lα were decreased significantly after 24 h incubation, indicating their anti-apoptotic property in these cells. These results indicated that cell metabolites stimulated by low-dose BLED irradiation have a cytoprotective effect on cell injury via increasing transient intracellular ER stress. Further studies remain to provide the molecular mechanisms of LCM for cytoprotective activity.

Light-Emitting Diode treatment ameliorates allergic lung inflammation in experimental model of asthma induced by ovalbumin

Since asthma is a multifactorial disease where treatment sometimes is not effective, new therapies that improve the respiratory discomfort of patients are of great importance. Phototherapy as Light-emitting diode (LED) has emerged as a treatment that presents good results for diseases that are characterized by inflammation. Thus, our objective was to investigate the effects of LED on lung inflammation, by an evaluation of lung cell infiltration, mucus secretion, oedema, and the production of cytokines. Male Balb/c mice were or not sensitized and challenged with ovalbumin (OVA) and treated or not with LED therapy (1 h and 4 h after each OVA challenge). Twenty-four hours after the last OVA challenge, analyzes were performed. Our results showed that LED treatment in asthmatic mice reduced the lung cell infiltration, the mucus production, the oedema, and the tracheal's contractile response. It also increased the IL-10 and the IFN-gamma levels. The effects of LED treatment on lung inflammation may be modulated by IL-10, IFN-gamma, and by mast cells. This study may provide important information about the effects of LED, and in addition, it may open the possibility of a new approach for the treatment of asthma.

Asiatic acid inhibits LPS-induced inflammatory response in human gingival fibroblasts

Asiatic acid, a triterpenoid component isolated from Centella asiatica (L.) Urban, possesses antioxidative and anti-inflammatory activities. In this study, we aimed to investigate the anti-inflammatory effects of asiatic acid both in vivo and in vitro. HGFs or RAW264.7 cells were treated with asiatic acid 1h before LPS treatment. Cell viability was measured by MTT assay. The levels of PGE2, NO, IL-6, and IL-8 were detected by ELISA. Protein expression levels were detected by western blot analysis. In vivo, asiatic acid significantly inhibited LPS-induced IL-6 and IL-8 expression levels in gingival tissues. In vitro, LPS-induced PGE2, NO, IL-6, and IL-8 production was significantly attenuated by asiatic acid. Asiatic acid also inhibited p65 NF-κB phosphorylation induced by LPS in HGFs. The expression of PPAR-γ was up-regulated by asiatic acid. Furthermore, GW9662, a PPAR-γ inhibitor, attenuated the inhibitory effect of asiatic acid on PGE2, NO, IL-6, and IL-8 production. Our results suggest that asiatic acid activates PPAR-γ, which subsequently inhibits LPS-induced NF-κB activation and inflammatory mediators production. Asiatic acid may offer therapeutic potential for the treatment of periodontitis.

Photobiomodulation therapy improves both inflammatory and fibrotic parameters in experimental model of lung fibrosis in mice

Lung fibrosis (LF) is a chronic and progressive lung disease characterized by pulmonary parenchyma progressive lesion, inflammatory infiltration, and interstitial fibrosis. It is developed by excessive collagen deposition and other cellular matrix components, resulting in severe changes in the alveolar architecture. Considering the absence of effective treatment, the aim of this study was to investigate the effect of photobiomodulation therapy (PBMT) on the development of PF. For this purpose, we used C57BL6 mice subjected to induction of LF by bleomycin administration (1.5 U/kg) by orotracheal route and, after 14 days of the induction, mice were treated with PBMT applied to the thorax 1×/day for 8 days (wavelength 660 ± 20 nm, power 100 mW, radiant exposure 5 J/cm², irradiance 33.3 mW/cm², spot size 2.8cm², total energy 15 J, time of irradiation: 150 s) and inflammatory and fibrotic parameters were evaluated with or without PBMT. Our results showed that PBMT significantly reduced the number of inflammatory cells in the alveolar space, collagen production, interstitial thickening, and static and dynamic pulmonary elastance. In addition, we observed reduced levels of IL-6 e CXCL1/KC released by pneumocytes in culture as well as reduced level of CXCL1/KC released by fibroblasts in culture. We can conclude that the PBMT improves both inflammatory and fibrotic parameters showing a promising therapy which is economical and has no side effects.

Mechanisms and applications of the anti-inflammatory effects of photobiomodulation

Photobiomodulation (PBM) also known as low-level level laser therapy is the use of red and near-infrared light to stimulate healing, relieve pain, and reduce inflammation. The primary chromophores have been identified as cytochrome c oxidase in mitochondria, and calcium ion channels (possibly mediated by light absorption by opsins). Secondary effects of photon absorption include increases in ATP, a brief burst of reactive oxygen species, an increase in nitric oxide, and modulation of calcium levels. Tertiary effects include activation of a wide range of transcription factors leading to improved cell survival, increased proliferation and migration, and new protein synthesis. There is a pronounced biphasic dose response whereby low levels of light have stimulating effects, while high levels of light have inhibitory effects. It has been found that PBM can produce ROS in normal cells, but when used in oxidatively stressed cells or in animal models of disease, ROS levels are lowered. PBM is able to up-regulate anti-oxidant defenses and reduce oxidative stress. It was shown that PBM can activate NF-kB in normal quiescent cells, however in activated inflammatory cells, inflammatory markers were decreased. One of the most reproducible effects of PBM is an overall reduction in inflammation, which is particularly important for disorders of the joints, traumatic injuries, lung disorders, and in the brain. PBM has been shown to reduce markers of M1 phenotype in activated macrophages. Many reports have shown reductions in reactive nitrogen species and prostaglandins in various animal models. PBM can reduce inflammation in the brain, abdominal fat, wounds, lungs, spinal cord.

High fluence light emitting diode-generated red light modulates characteristics associated with skin fibrosis

Skin fibrosis, often referred to as skin scarring, is a significant international health problem with limited treatment options. The hallmarks of skin fibrosis are increased fibroblast proliferation, collagen production, and migration speed. Recently published clinical observations indicate that visible red light may improve skin fibrosis. In this study we hypothesize that high-fluence light-emitting diode-generated red light (HF-LED-RL) modulates the key cellular features of skin fibrosis by decreasing cellular proliferation, collagen production, and migration speed of human skin fibroblasts. Herein, we demonstrate that HF-LED-RL increases reactive oxygen species (ROS) generation for up to 4 hours, inhibits fibroblast proliferation without increasing apoptosis, inhibits collagen production, and inhibits migration speed through modulation of the phosphoinositide 3-kinase (PI3K)/Akt pathway. We demonstrate that HF-LED-RL is capable of inhibiting the unifying cellular processes involved in skin fibrosis including fibroblast proliferation, collagen production, and migration speed. These findings suggest that HF-LED-RL may represent a new approach to treat skin fibrosis. LED advantages include low cost, portability, and ease of use. Further characterizing the photobiomodulatory effects of HF-LED-RL on fibroblasts and investigating the anti-fibrotic effects of HF-LED-RL in human subjects may provide new insight into the utility of this therapeutic approach for skin fibrosis.

Visible Red Light Emitting Diode Photobiomodulation for Skin Fibrosis: Key Molecular Pathways

Skin fibrosis, also known as skin scarring, is an important global health problem that affects an estimated 100 million persons per year worldwide. Current therapies are associated with significant side effects and even with combination therapy, progression, and recurrence is common. Our goal is to review the available published data available on light-emitting diode-generated (LED) red light phototherapy for treatment of skin fibrosis. A search of the published literature from 1 January 2000 to present on the effects of visible red light on skin fibrosis, and related pathways was performed in January 2016. A search of PubMed and EMBASE was completed using specific keywords and MeSH terms. "Fibrosis" OR "skin fibrosis" OR "collagen" was combined with ("light emitting diode," "LED," "laser," or "red light"). The articles that were original research studies investigating the use of visible red light to treat skin fibrosis or related pathways were selected for inclusion. Our systematic search returned a total of 1376 articles. Duplicate articles were removed resulting in 1189 unique articles, and 133 non-English articles were excluded. From these articles, we identified six articles related to LED effects on skin fibrosis and dermal fibroblasts. We augmented our discussion with additional in vitro data on related pathways. LED phototherapy is an emerging therapeutic modality for treatment of skin fibrosis. There is a growing body of evidence demonstrating that visible LED light, especially in the red spectrum, is capable of modulating key cellular characteristic associated with skin fibrosis. We anticipate that as the understanding of LED-RL's biochemical mechanisms and clinical effects continue to advance, additional therapeutic targets in related pathways may emerge. We believe that the use of LED-RL, in combination with existing and new therapies, has the potential to alter the current treatment paradigm of skin fibrosis. There is a current lack of clinical trials investigating the efficacy of LED-RL to treat skin fibrosis. Randomized clinical trials are needed to demonstrate visible red light's clinical efficacy on different types of skin fibrosis.

Hemoglobin receptor protein from Porphyromonas gingivalis induces interleukin-8 production in human gingival epithelial cells through stimulation of the mitogen-activated protein kinase and NF-κB signal transduction pathways

Periodontitis is an inflammatory disease of polymicrobial origin affecting the tissues supporting the tooth. The oral anaerobic bacterium Porphyromonas gingivalis, which is implicated as an important pathogen for chronic periodontitis, triggers a series of host inflammatory responses that promote the destruction of periodontal tissues. Among the virulence factors of P. gingivalis, hemoglobin receptor protein (HbR) is a major protein found in culture supernatants. In this study, we investigated the roles of HbR in the production of inflammatory mediators. We found that HbR induced interleukin-8 (IL-8) production in the human gingival epithelial cell line Ca9-22. p38 mitogen-activated protein kinase (MAPK) and extracellular signal-related kinase 1/2 (Erk1/2) were activated in HbR-stimulated Ca9-22 cells. Inhibitors of p38 MAPK (SB203580) and Erk1/2 (PD98059) blocked HbR-induced IL-8 production. Additionally, HbR stimulated the translocation of NF-κB-p65 to the nucleus, consistent with enhancement of IL-8 expression by activation of the NF-κB pathway. In addition, small interfering RNA (siRNA) targeting activating transcription factor 2 (ATF-2) or cyclic AMP-response element-binding protein (CREB) inhibited HbR-induced IL-8 production. Moreover, pretreatment with SB203580 and PD98059 reduced HbR-induced phosphorylation of CREB and ATF-2, respectively. Combined pretreatment with an inhibitor of NF-κB (BAY11-7082) and SB203580 was more efficient in inhibiting the ability of HbR to induce IL-8 production than pretreatment with either BAY11-7082 or SB203580 alone. Thus, in Ca9-22 cells, the direct activation of p38 MAPK and Erk1/2 by HbR caused the activation of the transcription factors ATF-2, CREB, and NF-κB, thus resulting in the induction of IL-8 production.

Curcumin attenuates cyclooxygenase-2 expression via inhibition of the NF-κB pathway in lipopolysaccharide-stimulated human gingival fibroblasts

Porphyromonas gingivalis lipopolysaccharide (LPS) induces the expression of the cyclooxygenase-2 (COX-2), which contributes to the process of periodontitis. Curcumin, a constituent of turmeric, exhibits anti-inflammatory properties. We have investigated the anti-inflammatory effect of curcumin in human gingival fibroblasts (HGFs) stimulated by P. gingivalis LPS and its mechanism of action. HGFs pretreated with curcumin were stimulated by P. gingivalis LPS. COX-2 mRNA and protein expressions were analysed by real-time PCR and Western blot analysis. Activation of nuclear factor kappa B (NF-κB) was analysed by the NF-κB-dependent luciferase activity and electrophoretic mobility-shift assay (EMSA). Curcumin inhibited COX-2 mRNA and protein synthesis in LPS-stimulated HGFs in a dose-dependent manner. P. gingivalis LPS activated NF-κB-dependent transcription in HGFs, which were also downregulated by pretreatment with curcumin. Therefore, curcumin can inhibit P. gingivalis LPS-induced COX-2 expression, which may be due to the inhibition of the NF-κB pathway.

Diacerein: a potential therapeutic drug for periodontal disease

Periodontal diseases are chronic inflammatory diseases characterized by the destruction of the tooth-supporting structures. They are the most prevalent form of bone pathology in humans and act as a modifying factor of the systemic health of patients. Accumulating evidence has provided insight into mechanisms of periodontal inflammation revealing that oral pathogens induce inflammatory cascades, including a variety of cytokines produced by different cell types, which promotes host-mediated tissue destruction. Cytokine networks established in diseased periodontal tissues are extremely complex, and substances regulating immuno-inflammatory reactions and signaling pathways, in addition to traditional periodontal treatment, could potentially be targeted as an approach for prevention and treatment of periodontal diseases. Diacerein, a purified anthraquinone derivative, was derived originally from plants with profound anti-inflammatory and analgesic activities. Its wide range of biological activities have been applied and discussed for several decades; however, studies of diacerein have mainly concentrated on effects on joint-derived tissues/cells, which suggest a beneficial role in osteoarthritis treatment. Diacerein reduces association of the IL-1 receptor to form heterodimer complexes, repressing IL-1 and its related downstream events and impairing active IL-1 release due to the inhibition of the IL-1-converting enzyme (ICE). To date, there are no reports describing the therapeutic effect of diacerein for treatment of periodontitis. Given the involvement of inflammation and occurrence of tissue destruction in periodontal disease, we propose that diacerein might be a promising biological drug for periodontal disease due to its therapeutic advantages. In addition, we hypothesize that the underlying mechanisms might involve the capacity of diacerein to selectively inhibit signal transduction to affect the cytokine profiles and, consequently, produce the outcome of ameliorating disease breakdown.