Microglia modulation with 1070-nm light attenuates Aβ burden and cognitive impairment in Alzheimer's disease mouse model

Accelerated Molecular Transportation in the Brain Extracellular Space with 755-nm Light Attenuates Post-Stroke Cognitive Impairment in Rats

Ischemic stroke exacts a heavy toll in death and disability worldwide. After ischemic stroke, the accumulation of pathobiomolecules in the brain extracellular space (ECS) will exacerbate neurological damage and cognitive impairment. Photobiomodulation (PBM) has been demonstrated to improve cognitive function in Alzheimer's disease mouse models by accelerating molecular transportation in the brain ECS. This suggests that PBM may have a potential role in the accumulation of pathobiomolecules in the brain ECS following ischemic stroke. In this study, we developed a PBM therapy apparatus with custom parameters. By evaluating the treatment effect, we identified that 755 nm was the optimal light wavelength for ischemic stroke in rats with transient middle cerebral artery occlusion/reperfusion. Extracellular diffusion and interstitial fluid (ISF) drainage were measured using a tracer-based magnetic resonance imaging method. Our results showed that PBM accelerated molecular transportation in the brain ECS and ISF drainage, promoting the clearance of pro-inflammatory cytokines and reducing the deposition of pathological proteins. Consequently, the infarct volume decreased and neurological cognitive function was improved. Besides, the acceleration of ISF drainage was achieved by reducing expression and restoring polarization of aquaporin 4 (AQP4) in the peri-infarct area. In summary, we demonstrated that PBM could alleviate ischemia-reperfusion injury and prevent post-stroke cognitive impairment by accelerating molecular transportation in the brain ECS, paving a pathway for ischemic stroke treatment via the light-ECS interaction.

Meningeal lymphatic drainage: novel insights into central nervous system disease

In recent years, increasing evidence has suggested that meningeal lymphatic drainage plays a significant role in central nervous system (CNS) diseases. Studies have indicated that CNS diseases and conditions associated with meningeal lymphatic drainage dysfunction include neurodegenerative diseases, stroke, infections, traumatic brain injury, tumors, functional cranial disorders, and hydrocephalus. However, the understanding of the regulatory and damage mechanisms of meningeal lymphatics under physiological and pathological conditions is currently limited. Given the importance of a profound understanding of the interplay between meningeal lymphatic drainage and CNS diseases, this review covers seven key aspects: the development and structure of meningeal lymphatic vessels, methods for observing meningeal lymphatics, the function of meningeal lymphatics, the molecular mechanisms of meningeal lymphatic injury, the relationships between meningeal lymphatic vessels and CNS diseases, potential regulatory mechanisms of meningeal lymphatics, and conclusions and outstanding questions. We will explore the relationship between the development, structure, and function of meningeal lymphatics, review current methods for observing meningeal lymphatic vessels in both animal models and humans, and identify unresolved key points in meningeal lymphatic research. The aim of this review is to provide new directions for future research and therapeutic strategies targeting meningeal lymphatics by critically analyzing recent advancements in the field, identifying gaps in current knowledge, and proposing innovative approaches to address these gaps.

Unlocking the potential of photobiomodulation therapy for brain neurovascular coupling: The biological effects and medical applications

Photobiomodulation (PBM) therapy stands as an innovative neurostimulation modality that has demonstrated both efficacy and safety in improving brain function. This therapy exerts multifaceted influences on neurons, blood vessels, and their intricate interplay known as neurovascular coupling (NVC). Growing evidence indicates that NVC may present a promising target for PBM intervention. However, the detailed mechanisms underlying its therapeutic benefits remain to be fully understood. This review aims to elucidate the potential metabolic pathways and signaling cascades involved in the modulatory effects of PBM, while also exploring the extensive repertoire of PBM applications in neurologic and psychiatric conditions. The prospects of PBM within the realm of NVC investigation are intensively considered, providing deeper insights into the powerful capabilities of PBM therapy and its potential to revolutionize neurostimulation treatments.

Photobiomodulation modulates mitochondrial energy metabolism and ameliorates neurological damage in an APP/PS1 mousmodel of Alzheimer's disease

BACKGROUND

Alzheimer's disease (AD) is a neurodegenerative disease. Amyloid β-protein (Aβ) is one of the key pathological features of AD, which is cytotoxic and can damage neurons, thereby causing cognitive dysfunction. Photobiomodulation (PBM) is a non-invasive physical therapy that induces changes in the intrinsic mechanisms of cells and tissues through low-power light exposure. Although PBM has been employed in the treatment of AD, the effect and precise mechanism of PBM on AD-induced neurological damage are still unclear.

METHODS

In vivo experiments, PBM (808 nm, 20 mW/cm2) was used to continuously interfere with APP/PS1 mice for 6 weeks, and then their cognitive function and AD pathological changes were evaluated. In vitro experiments, lipopolysaccharide (LPS) was used to induce microglia to model inflammation, and the effect of PBM treatment on microglia polarization status and phagocytic Aβ ability was evaluated. Hexokinase 2 (HK2) inhibitor 3-bromopyruvate (3BP) was used to study the effect of PBM treatment on mitochondrial energy metabolism in microglia.

RESULTS

PBM further ameliorates AD-induced cognitive impairment by alleviating neuroinflammation and neuronal apoptosis, thereby attenuating nerve damage. In addition, PBM can also reduce neuroinflammation by promoting microglial anti-inflammatory phenotypic polarization; Promotes Aβ clearance by enhancing the ability of microglia to engulf Aβ. Among them, PBM regulates microglial polarization and inhibits neuronal apoptosis, which may be related to its regulation of mitochondrial energy metabolism, promotion of oxidative phosphorylation, and inhibition of glycolysis.

CONCLUSION

PBM regulates neuroinflammatory response and inhibits neuronal apoptosis, thereby repairing Aβ-induced neuronal damage and cognitive dysfunction. Mitochondrial energy metabolism plays an important role in PBM in improving nerve injury in AD mice. This study provides theoretical support for the subsequent application of PBM in the treatment of AD.

Photobiomodulation Combined With Human Umbilical Cord Mesenchymal Stem Cells Modulates the Polarization of Microglia

Neuroinflammation plays a key role in the development of neurodegenerative diseases, with microglia regulating this process through pro-inflammatory M1 and anti-inflammatory M2 phenotypes. Studies have shown that human umbilical cord mesenchymal stem cells (hUCMSCs) modulate neuroinflammation by secreting anti-inflammatory cytokines. Photobiomodulation (PBM), a non-invasive therapy, has demonstrated significant potential in alleviating neuroinflammation. This study examines the combined effects of PBM and hUCMSCs in an in vitro microglial inflammation model and an LPS-induced mouse model. The results show that PBM-pretreated hUCMSCs promoted M2 polarization and improved cognitive function in mice by downregulating the Notch signaling pathway, suggesting a promising new approach for treating neurodegenerative diseases.

Monitoring photobiomodulation of amyloid-β aggregation in 3D cultured cells using label-free nonlinear optical imaging

The accumulation of beta-amyloid (Aβ) peptide aggregates, commonly known as plaques, is considered a key hallmark in the development of Alzheimer's disease (AD). Recently, low-level light therapy (LLLT), also referred to as photobiomodulation (PBM), has emerged as a promising treatment approach for AD. Previous studies have shown that PBM reduces Aβ load primarily by enhancing the clearance capabilities of glia cells. However, it remains unclear whether PBM can directly reduce the formation of Aβ plaques in neuronal cells independent of the glia cell effect. In this study, we employed three-dimensional (3D) cultured HEK 293 APPsw cells as an AD model to investigate the impact of PBM on Aβ aggregation. We demonstrated that label-free two-photon excited fluorescence (TPEF) imaging and second harmonic generation (SHG) imaging are effective tools for monitoring Aβ aggregation in 3D cell models. The TPEF imaging results and subsequent quantification revealed that PBM, particularly with low-level near-infrared light from an 808 nm laser (compared to 1064, 1210, and 1470 nm lasers), significantly reduced Aβ aggregation, specifically plaques formation, in the 3D cultured cells, with the effect found to be dose-dependent. Moreover, a comprehensive analysis of protein expression in the 3D cultured cells revealed that PBM induces overexpression of the LRP1 receptor, which mediates Aβ degradation and thus leads to the reduction of Aβ aggregation. This study highlights the use of label-free nonlinear optical imaging to monitor Aβ aggregation in AD progression and provides novel insights into the effects of PBM on Aβ plaque formation in AD models.

Circadian rhythm, microglia-mediated neuroinflammation, and Alzheimer's disease

Microglia, the brain's resident macrophages, are key mediators of neuroinflammation, responding to immune pathogens and toxins. They play a crucial role in clearing cellular debris, regulating synaptic plasticity, and phagocytosing amyloid-β (Aβ) plaques in Alzheimer's disease (AD). Recent studies indicate that microglia not only exhibit intrinsic circadian rhythms but are also regulated by circadian clock genes, influencing specific functions such as phagocytosis and the modulation of neuroinflammation. Disruption of the circadian rhythm is closely associated with AD pathology. In this review, we will provide an overview of how circadian rhythms regulate microglia-mediated neuroinflammation in the progression of AD, focusing on the pathway from the central nervous system (CNS) and the peripheral immune system. We also discuss potential therapeutic targets, including hormone modulation, lifestyle interventions, and anti-inflammatory therapies, aimed at maintaining brain health in AD. This will shed light on the involvement of circadian rhythm in AD and explore new avenues for AD treatment.

Non-pharmacological treatment of Alzheimer's disease: an update

Alzheimer's disease (AD) is a neurodegenerative disorder that significantly impairs memory, cognitive function, and the ability to perform daily tasks. The pathological features of AD include β-amyloid plaques, neurofibrillary tangles, and neuronal loss. Current AD treatments target pathological changes but often fail to noticeably slow disease progression and can cause severe complications, limiting their effectiveness. In addition to therapies targeting the core pathology of AD, a more comprehensive approach may be needed for its treatment. In recent years, non-pharmacological treatments such as physical therapy, exercise therapy, cell therapy, and nanoparticles have shown great potential in mitigating disease progression and alleviating clinical symptoms. This article reviews recent advances in non-pharmacological treatment approaches for AD, highlighting their contributions to AD management and facilitating the exploration of novel therapeutic strategies.

Quantitative simulation of near-infrared light treatment for Alzheimer's disease using patient-individualized optical-parametric phantoms

Significance

Alzheimer's disease (AD) is a brain disorder characterized by its multifactorial nature and complex pathogenesis, highlighting the necessity for multimodal and individualized interventions. Among emerging therapies, near-infrared (NIR) light treatment shows promise as a therapeutic modality for AD. However, existing clinical studies lack sufficient data on light dosimetry, parameter optimization, and dose-response.

Aim

A versatile framework was developed to enable patient-individualized Monte Carlo simulation. A standardized dataset was established, including digital phantoms derived from 20 AD patients who received NIR light treatment.

Approach

The phantoms were synthesized and mapped with multispectral optical parameters, integrating cortical parcellation, subcortical segmentation, and sparse annotation. Structure-related light fluence pathways and dose-response relationships were elucidated using simulation results and cognitive/functional assessments.

Results

The capability for enhancing simulation fidelity and exploring dose-response relationships was verified using standard templates and clinical data. Linear independence was identified between changes in activities of daily living scale scores and energy deposition in gray matter.

Conclusions

The framework offers a solution toward dose-response analysis, parameter optimization, and safety control in the clinical translation for multiple treatment paradigms, demonstrating promise for individualized, standardized, and precise intervention planning.

Photobiomodulation: shining a light on depression

Depression is a prevalent public health issue, characterized by persistent low mood, impaired concentration, and diminished motivation. Photobiomodulation (PBM), which involves the application of red or near-infrared light, modulates physiological processes by enhancing cerebral blood flow, reducing inflammation, inhibiting apoptosis, and promoting neurogenesis. PBM can be administered transcranially or through systemic approaches, offering a potentially effective intervention for depression. This review discusses the characteristics of PBM, its underlying neurobiological mechanisms, and relevant physical parameters. Recent progress in both animal and clinical research underscores PBM's therapeutic potential for depression and emphasizes the need for further studies to establish a robust theoretical basis for standardized treatment protocols.

Mystery of gamma wave stimulation in brain disorders

Neuronal oscillations refer to rhythmic and periodic fluctuations of electrical activity in the central nervous system that arise from the cellular properties of diverse neuronal populations and their interactions. Specifically, gamma oscillations play a crucial role in governing the connectivity between distinct brain regions, which are essential in perception, motor control, memory, and emotions. In this context, we recapitulate various current stimulation methods to induce gamma entrainment. These methods include sensory stimulation, optogenetic modulation, photobiomodulation, and transcranial electrical or magnetic stimulation. Simultaneously, we explore the association between abnormal gamma oscillations and central nervous system disorders such as Alzheimer's disease, Parkinson's disease, stroke, schizophrenia, and autism spectrum disorders. Evidence suggests that gamma entrainment-inducing stimulation methods offer notable neuroprotection, although somewhat controversial. This review comprehensively discusses the functional role of gamma oscillations in higher-order brain activities from both physiological and pathological perspectives, emphasizing gamma entrainment as a potential therapeutic approach for neuropsychiatric disorders. Additionally, we discuss future opportunities and challenges in implementing such strategies.

Photobiomodulation in the aging brain: a systematic review from animal models to humans

Aging is a multifactorial biological process that may be associated with cognitive decline. Photobiomodulation (PBM) is a non-pharmacological therapy that shows promising results in the treatment or prevention of age-related cognitive impairments. The aim of this review is to compile the preclinical and clinical evidence of the effect of PBM during aging in healthy and pathological conditions, including behavioral analysis and neuropsychological assessment, as well as brain-related modifications. 37 studies were identified by searching in PubMed, Scopus, and PsycInfo databases. Most studies use wavelengths of 800, 810, or 1064 nm but intensity and days of application were highly variable. In animal studies, it has been shown improvements in spatial memory, episodic-like memory, social memory, while different results have been found in recognition memory. Locomotor activity improved in Parkinson disease models. In healthy aged humans, it has been outlined improvements in working memory, cognitive inhibition, and lexical/semantic access, while general cognition was mainly enhanced on Alzheimer disease or mild cognitive impairment. Anxiety assessment is scarce and shows mixed results. As for brain activity, results outline promising effects of PBM in reversing metabolic alterations and enhancing mitochondrial function, as evidenced by restored CCO activity and ATP levels. Additionally, PBM demonstrated neuroprotective, anti-inflammatory, immunomodulatory and hemodynamic effects. The findings suggest that PBM holds promise as a non-invasive intervention for enhancing cognitive function, and in the modulation of brain functional reorganization. It is necessary to develop standardized protocols for the correct, beneficial, and homogeneous use of PBM.

Photobiomodulation ameliorates ovarian aging by alleviating oxidative stress and inflammation damage and improving mitochondrial function

Ovarian aging is a serious clinical concern. Few safe and effective methods are currently available to improve ovarian functions. Photobiomodulation (PBM) is a safe and noninvasive physical therapy that can modulate a series of biological processes. Recently, several studies have noted its potential to improve the function of ovary and reproductive cells. However, the effects of PBM treatment on natural ovarian aging remain unclear. In this study, we used a naturally reproductive aging mouse model to observe the effect of PBM on ovarian function. Young and aged female ICR mice were treated with or without PBM for 2 months. PBM was performed using a semiconductor InGaAlP laser emitting at 650 nm (80 mW, 6.7 mW/cm2 for 5 or 10 min, resulting in a dose of 2 or 4 J/cm2, respectively). After treatment, the effects of PBM and its role in oxidative stress, inflammation, and mitochondrial function were investigated. We found that PBM (4 J/cm2) effectively recovered the levels of sex hormones, increased the number of primordial and growing follicles, improved angiogenesis, and decreased cell apoptosis in naturally aged mice. Moreover, PBM reduced oxidative stress, inhibited chronic ovarian inflammation, and improved mitochondrial function in aged ovaries. Similar protective effects of PBM were observed in a hydrogen peroxide-induced oxidative stress model of human granulosa cell line (KGN) in vitro. Increased cell viability, cell proliferation, hormone secretion, mitochondrial membrane potential, and adenosine triphosphate levels and decreased apoptosis and oxidative stress were detected in KGN cells after PBM treatment. Collectively, this study suggest that PBM treatment is beneficial for restoring ovarian function in naturally reproductive aging mice and has a significant protective effect against oxidative stress damage in KGN cells. The mechanisms underlying the benefits of PBM in ovarian aging include antioxidant stress, reduction of inflammation, and preservation of mitochondrial function. Therefore, this study emphasizes the potential of PBM as a therapeutic intervention to ameliorate ovarian aging.

Photobiomodulation as a Potential Treatment for Alzheimer's Disease: A Review Paper

BACKGROUND

Alzheimer's disease (AD), the most prevalent form of dementia, is a leading neurodegenerative disorder currently affecting approximately 55 million individuals globally, a number projected to escalate to 139 million by 2050. Despite extensive research spanning several decades, the cure for AD remains at a developing stage. The only existing therapeutic options are limited to symptom management, and are often accompanied by adverse side effects. The pathological features of AD, including the accumulation of beta-amyloid plaques and tau protein tangles, result in progressive neuronal death, synaptic loss, and brain atrophy, leading to significant cognitive decline and a marked reduction in quality of life.

OBJECTIVE

In light of the shortcomings of existing pharmacological interventions, this review explores the potential of photobiomodulation (PBM) as a non-invasive therapeutic option for AD. PBM employs infrared light to facilitate cellular repair and regeneration, focusing on addressing the disease's underlying biomechanical mechanisms.

METHOD

This paper presents a comprehensive introduction to the mechanisms of PBM and an analysis of preclinical studies evaluating its impact on cellular health, cognitive function, and disease progression in AD.The review provides a comprehensive overview of the various wavelengths and application methods, evaluating their efficacy in mitigating AD-related symptoms.

CONCLUSIONS

The findings underscore the significant potential of PBM as a safe and effective alternative treatment for Alzheimer's disease, emphasizing the necessity for further research and clinical trials to establish its therapeutic efficacy conclusively.

Near-infrared light stimulation regulates neural oscillation and memory behavior of mice with Alzheimer's disease

Photobiomodulation (PBM) is a non-invasive neuromodulation technique for the brain. Low-intensity near-infrared light (1-500 mw) has demonstrated the ability to improve memory in Alzheimer's disease (AD) model mice, suggesting its potential for AD treatment. However, the impact of PBM on neural oscillations in the hippocampal region affected by AD remains unknown. In this study, AD model mice were subjected to PBM for 60 days and then tested using novel object recognition behavior (NOR) experiments. During behavioral experiments, local field potential signals (LFP) of the mice was recorded using a single electrode in the CA1 region to analyze memory ability and neural oscillation characteristics. The results revealed that mice stimulated with PBM exhibited significantly higher new object differentiation indices compared to the Sham group (p < 0.01). Furthermore, PBM stimulation led to a significant increase in relative power and sample entropy of theta and gamma bands (p < 0.01). The coupling intensities of θ-low-γ and θ-high-γ were also significantly higher in the PBM group compared to the Sham group (p < 0.01). In conclusion, these findings suggest that PBM may improve memory ability in AD mice through regulation of neural oscillation characteristics, providing a theoretical basis for utilizing PBM as a treatment modality for Alzheimer's disease.

A novel neuroprotective method against ischemic stroke by accelerating the drainage of brain interstitial fluid

Ischemic stroke is a leading cause of death and disability worldwide. Inflammatory response after stroke determines the outcome of ischemic injury. A recent study has reported an efficient method, epidural arterial implantation (EAI), for accelerating interstitial fluid (ISF) drainage, which provides a promising strategy to clear pro-inflammatory cytokines in the brain extracellular space (ECS). In this study, the method of EAI was modified (m-EAI) to control its function of accelerating the ISF drainage at different time points following ischemic attack. The neuroprotective effect of m-EAI on ischemic stroke was evaluated with the transient middle cerebral artery occlusion (tMCAO) rat model. The results demonstrated the accumulation of IL-1β, IL-6, and TNF-α was significantly decreased by activating m-EAI at 7 d before and immediately after ischemic attack in tMCAO rats, accompanied with decreased infarct volume and improved neurological function. This study consolidates the hypothesis of exacerbated ischemic damage by inflammatory response and provides a new perspective to treat encephalopathy via brain ECS. Further research is essential to investigate whether m-EAI combined with neuroprotective drugs could enhance the therapeutic effect on ischemic stroke.

Neural stimulation and modulation with sub-cellular precision by optomechanical bio-dart

Neural stimulation and modulation at high spatial resolution are crucial for mediating neuronal signaling and plasticity, aiding in a better understanding of neuronal dysfunction and neurodegenerative diseases. However, developing a biocompatible and precisely controllable technique for accurate and effective stimulation and modulation of neurons at the subcellular level is highly challenging. Here, we report an optomechanical method for neural stimulation and modulation with subcellular precision using optically controlled bio-darts. The bio-dart is obtained from the tip of sunflower pollen grain and can generate transient pressure on the cell membrane with submicrometer spatial resolution when propelled by optical scattering force controlled with an optical fiber probe, which results in precision neural stimulation via precisely activation of membrane mechanosensitive ion channel. Importantly, controllable modulation of a single neuronal cell, even down to subcellular neuronal structures such as dendrites, axons, and soma, can be achieved. This bio-dart can also serve as a drug delivery tool for multifunctional neural stimulation and modulation. Remarkably, our optomechanical bio-darts can also be used for in vivo neural stimulation in larval zebrafish. This strategy provides a novel approach for neural stimulation and modulation with sub-cellular precision, paving the way for high-precision neuronal plasticity and neuromodulation.

Microglial Drivers of Alzheimer's Disease Pathology: An Evolution of Diverse Participating States

Microglia, the resident immune-competent cells of the brain, become dysfunctional in Alzheimer's disease (AD), and their aberrant immune responses contribute to the accumulation of pathological proteins and neuronal injury. Genetic studies implicate microglia in the development of AD, prompting interest in developing immunomodulatory therapies to prevent or ameliorate disease. However, microglia take on diverse functional states in disease, playing both protective and detrimental roles in AD, which largely overlap and may shift over the disease course, complicating the identification of effective therapeutic targets. Extensive evidence gathered using transgenic mouse models supports an active role of microglia in pathology progression, though results vary and can be contradictory between different types of models and the degree of pathology at the time of study. Here, we review microglial immune signaling and responses that contribute to the accumulation and spread of pathological proteins or directly affect neuronal health. We additionally explore the use of induced pluripotent stem cell (iPSC)-derived models to study living human microglia and how they have contributed to our knowledge of AD and may begin to fill in the gaps left by mouse models. Ultimately, mouse and iPSC-derived models have their own limitations, and a comprehensive understanding of microglial dysfunction in AD will only be established by an integrated view across models and an appreciation for their complementary viewpoints and limitations.

Photobiomodulation therapy mitigates depressive-like behaviors by remodeling synaptic links and mitochondrial function

Depression, a multifactorial mental disorder, characterized by cognitive slowing, anxiety, and impaired cognitive function, imposes a significant burden on public health. Photobiomodulation (PBM), involving exposure to sunlight or artificial light at a specific intensity and wavelength for a determined duration, influences brain activity, functional connectivity, and plasticity. It is recognized for its therapeutic efficacy in treating depression, yet its molecular and cellular underpinnings remain obscure. Here, we investigated the impact of PBM with 468 nm light on depression-like behavior and neuronal damage in the chronic unpredictable mild stress (CUMS) murine model, a commonly employed animal model for studying depression. Our results demonstrate that PBM treatment ameliorated behavioral deficits, inhibited neuroinflammation and apoptosis, and notably rejuvenates the hippocampal synaptic function in depressed mice, which may be mainly attributed to the up-regulation of brain-derived neurotrophic factor signaling pathways. In addition, in vitro experiments with a corticosterone-induced hippocampal neuron injury model demonstrate reduced oxidative stress and improved mitochondrial function, further validating the therapeutic potential of PBM. In summary, these findings suggest PBM as a promising, non-invasive treatment for depression, offering insights into its biological mechanisms and potential for clinical application.

Photobiomodulation in the infrared spectrum reverses the expansion of circulating natural killer cells and brain microglial activation in Sanfilippo mice

Sanfilippo syndrome results from inherited mutations in genes encoding lysosomal enzymes that catabolise heparan sulfate (HS), leading to early childhood-onset neurodegeneration. This study explores the therapeutic potential of photobiomodulation (PBM), which is neuroprotective and anti-inflammatory in several neurodegenerative diseases; it is also safe and PBM devices are readily available. We investigated the effects of 10-14 days transcranial PBM at 670 nm (2 or 4 J/cm2/day) or 904 nm (4 J/cm2/day) in young (3 weeks) and older (15 weeks) Sanfilippo or mucopolysaccharidosis type IIIA (MPS IIIA) mice. Although we found no PBM-induced changes in HS accumulation, astrocyte activation, CD206 (an anti-inflammatory marker) and BDNF expression in the brains of Sanfilippo mice, there was a near-normalisation of microglial activation in older MPS IIIA mice by 904 nm PBM, with decreased IBA1 expression and a return of their morphology towards a resting state. Immune cell immunophenotyping of peripheral blood with mass cytometry revealed increased pro-inflammatory signalling through pSTAT1 and p-p38 in NK and T cells in young but not older MPS IIIA mice (5 weeks of age), and expansion of NK, B and CD8+ T cells in older affected mice (17 weeks of age), highlighting the importance of innate and adaptive lymphocytes in Sanfilippo syndrome. Notably, 670 and 904 nm PBM both reversed the Sanfilippo-induced increase in pSTAT1 and p-p38 expression in multiple leukocyte populations in young mice, while 904 nm reversed the increase in NK cells in older mice. In conclusion, this is the first study to demonstrate the beneficial effects of PBM in Sanfilippo mice. The distinct reduction in microglial activation and NK cell pro-inflammatory signalling and number suggests PBM may alleviate neuroinflammation and lymphocyte activation, encouraging further investigation of PBM as a standalone, or complementary therapy in Sanfilippo syndrome.

Modifying Alzheimer's disease pathophysiology with photobiomodulation: model, evidence, and future with EEG-guided intervention

This manuscript outlines a model of Alzheimer's Disease (AD) pathophysiology in progressive layers, from its genesis to the development of biomarkers and then to symptom expression. Genetic predispositions are the major factor that leads to mitochondrial dysfunction and subsequent amyloid and tau protein accumulation, which have been identified as hallmarks of AD. Extending beyond these accumulations, we explore a broader spectrum of pathophysiological aspects, including the blood-brain barrier, blood flow, vascular health, gut-brain microbiodata, glymphatic flow, metabolic syndrome, energy deficit, oxidative stress, calcium overload, inflammation, neuronal and synaptic loss, brain matter atrophy, and reduced growth factors. Photobiomodulation (PBM), which delivers near-infrared light to selected brain regions using portable devices, is introduced as a therapeutic approach. PBM has the potential to address each of these pathophysiological aspects, with data provided by various studies. They provide mechanistic support for largely small published clinical studies that demonstrate improvements in memory and cognition. They inform of PBM's potential to treat AD pending validation by large randomized controlled studies. The presentation of brain network and waveform changes on electroencephalography (EEG) provide the opportunity to use these data as a guide for the application of various PBM parameters to improve outcomes. These parameters include wavelength, power density, treatment duration, LED positioning, and pulse frequency. Pulsing at specific frequencies has been found to influence the expression of waveforms and modifications of brain networks. The expression stems from the modulation of cellular and protein structures as revealed in recent studies. These findings provide an EEG-based guide for the use of artificial intelligence to personalize AD treatment through EEG data feedback.

Microglia and Astrocytes in Alzheimer's Disease: Significance and Summary of Recent Advances

Alzheimer's disease, one of the most common forms of dementia, is characterized by a slow progression of cognitive impairment and neuronal loss. Currently, approved treatments for AD are hindered by various side effects and limited efficacy. Despite considerable research, practical treatments for AD have not been developed. Increasing evidence shows that glial cells, especially microglia and astrocytes, are essential in the initiation and progression of AD. During AD progression, activated resident microglia increases the ability of resting astrocytes to transform into reactive astrocytes, promoting neurodegeneration. Extensive clinical and molecular studies show the involvement of microglia and astrocyte-mediated neuroinflammation in AD pathology, indicating that microglia and astrocytes may be potential therapeutic targets for AD. This review will summarize the significant and recent advances of microglia and astrocytes in the pathogenesis of AD in three parts. First, we will review the typical pathological changes of AD and discuss microglia and astrocytes in terms of function and phenotypic changes. Second, we will describe microglia and astrocytes' physiological and pathological role in AD. These roles include the inflammatory response, "eat me" and "don't eat me" signals, Aβ seeding, propagation, clearance, synapse loss, synaptic pruning, remyelination, and demyelination. Last, we will review the pharmacological and non-pharmacological therapies targeting microglia and astrocytes in AD. We conclude that microglia and astrocytes are essential in the initiation and development of AD. Therefore, understanding the new role of microglia and astrocytes in AD progression is critical for future AD studies and clinical trials. Moreover, pharmacological, and non-pharmacological therapies targeting microglia and astrocytes, with specific studies investigating microglia and astrocyte-mediated neuronal damage and repair, may be a promising research direction for future studies regarding AD treatment and prevention.

The 40-Hz White Light Emitting Diode to Alleviate Psychiatric Symptoms Induced by Streptozotocin In Vivo

Introduction

A 40-Hz white light emitting diode (WLED) has emerged as an alternative nonpharmacological and noninvasive approach to Alzheimer disease (AD). Here, we investigated the therapeutic effects of 40-Hz WLED on psychiatric symptoms (PS) and the contribution of mitochondrial factors in the early stages of sporadic AD (sAD) in rats.

Methods

In male Wistar rats, the AD model was induced via intracerebroventricular (ICV) injection of streptozotocin (STZ). After recovering (7 days) from stereotaxic surgery, 40-Hz WLED exposure was performed for 7 consecutive days lasting 15 min/d. Behavioral (elevated plus maze (EPM), force swim test, and social interaction test), enzymatic, and molecular assays were conducted 24 hours after the last 40-Hz WLED exposure.

Results

Behavioral tasks revealed that 40-Hz WLED exposure in STZ-induced toxicity rats lowered anxiety and depression and increased social interaction. Furthermore, the 40-Hz WLED therapy in STZ-induced toxicity rats increased catalase (CAT) activity in the amygdala, decreased the activity of monoamine oxidases A and B in the whole brain, and increased mitochondrial DNA in the hippocampus.

Conclusion

The current study supports that 40-Hz WLED therapy improved PS and biomarkers in the early stages of sAD. Also, a potential relationship between PS and alterations in mitochondrial markers in certain brain regions seems to exist.

Terahertz Irradiation Improves Cognitive Impairments and Attenuates Alzheimer's Neuropathology in the APPSWE/PS1DE9 Mouse: A Novel Therapeutic Intervention for Alzheimer's Disease

Alzheimer's disease (AD) is a progressive neurodegenerative disease characterized by the deposition of amyloid-β (Aβ), neurofibrillary tangles, neuroinflammation, and neurodegeneration in the brain. In recent years, considering the unsatisfied benefits of pharmacological therapies, non-pharmacological therapy has become a research hotspot for AD intervention. Terahertz (THz) waves with a range between microwave and infrared regions in the electromagnetic spectrum and high permeability to a wide range of materials have great potential in the bioengineering field. However, its biological impacts on the central nervous system, under either physiological or pathological conditions, are poorly investigated. In this study, we first measured the 0.14 THz waves penetration across the skull of a C57BL/6 mouse and found the percentage of THz penetration to be ~70%, guaranteeing that THz waves can reach the relevant brain regions. We then exposed the APPSWE/PS1DE9 mouse model of AD to repeated low-frequency THz waves on the head. We demonstrated that THz waves treatment significantly improved the cognitive impairment and alleviated AD neuropathology including Aβ deposition and tau hyperphosphorylation in the AD mice. Moreover, THz waves treatment effectively attenuated mitochondrial impairment, neuroinflammation, and neuronal loss in the AD mouse brain. Our findings reveal previously unappreciated beneficial effects of THz waves treatment in AD and suggest that THz waves may have the potential to be used as a novel therapeutic intervention for this devastating disease.

Photobiomodulation therapy moderates cancer cachexia-associated muscle wasting through activating PI3K/AKT/FoxO3a pathway

Cancer cachexia-associated muscle wasting as a multifactorial wasting syndrome, is an important factor affecting the long-term survival rate of tumor patients. Photobiomodulation therapy (PBMT) has emerged as a promising tool to cure and prevent many diseases. However, the effect of PBMT on skeletal muscle atrophy during cancer progression has not been fully demonstrated yet. Here, we found PBMT alleviated the atrophy of myotube diameter induced by cancer cells in vitro, and prevented cancer-associated muscle atrophy in mice bearing tumor. Mechanistically, the alleviation of muscle wasting by PBMT was found to be involved in inhibiting E3 ubiquitin ligases MAFbx and MuRF-1. In addition, transcriptomic analysis using RNA-seq and GSEA revealed that PI3K/AKT pathway might be involved in PBMT-prevented muscle cachexia. Next, we showed the protective effect of PBMT against muscle cachexia was totally blocked by AKT inhibitor in vitro and in vivo. Moreover, PBMT-activated AKT promoted FoxO3a phosphorylation and thus inhibiting the nucleus entry of FoxO3a. Lastly, in cisplatin-treated muscle cachexia model, PBMT had also been shown to ameliorate muscle atrophy through enhancing PI3K/AKT pathway to suppress MAFbx and MuRF-1 expression. These novel findings revealed that PBMT could be a promising therapeutic approach in treating muscle cachexia induced by cancer.

Near-Infrared II Photobiomodulation Preconditioning Ameliorates Stroke Injury via Phosphorylation of eNOS

BACKGROUND

The current management of patients with stroke with intravenous thrombolysis and endovascular thrombectomy is effective only when it is timely performed on an appropriately selected but minor fraction of patients. The development of novel adjunctive therapy is highly desired to reduce morbidity and mortality with stroke. Since endothelial dysfunction is implicated in the pathogenesis of stroke and is featured with suppressed endothelial nitric oxide synthase (eNOS) with concomitant nitric oxide deficiency, restoring endothelial nitric oxide represents a promising approach to treating stroke injury.

METHODS

This is a preclinical proof-of-concept study to determine the therapeutic effect of transcranial treatment with a low-power near-infrared laser in a mouse model of ischemic stroke. The laser treatment was performed before the middle cerebral artery occlusion with a filament. To determine the involvement of eNOS phosphorylation, unphosphorylatable eNOS S1176A knock-in mice were used. Each measurement was analyzed by a 2-way ANOVA to assess the effect of the treatment on cerebral blood flow with laser Doppler flowmetry, eNOS phosphorylation by immunoblot analysis, and stroke outcomes by infarct volumes and neurological deficits.

RESULTS

Pretreatment with a 1064-nm laser at an irradiance of 50 mW/cm2 improved cerebral blood flow, eNOS phosphorylation, and stroke outcomes.

CONCLUSIONS

Near-infrared II photobiomodulation could offer a noninvasive and low-risk adjunctive therapy for stroke injury. This new modality using a physical parameter merits further consideration to develop innovative therapies to prevent and treat a wide array of cardiovascular diseases.

Unleashing light's healing power: an overview of photobiomodulation for Alzheimer's treatment

Aim: Photobiomodulation involves the use of low-level light therapy or near-infrared light therapy found to be useful in the treatment of a wide range of neurological diseases. Objective: The aim is to review the mechanism and clinical applications of photobiomodulation therapy (PBMT) in managing Alzheimer's disease. Methods: To ensure that the consensus statement accurately reflects both the experts' viewpoint and the most recent developments in the field, the expert opinions were recorded and thoroughly reviewed. Results: PBMT elicits reduction of beta-amyloid plaque, restoration of mitochondrial function, anti-inflammatory and antioxidant properties with a stimulation in ATP synthesis. Conclusion: The PBMT could be helpful in patients non-responsive to traditional pharmacological therapy providing significant aid in the management of Alzheimer's disease when introduced into the medical field.

Photobiomodulation in experimental models of Alzheimer's disease: state-of-the-art and translational perspectives

Alzheimer's disease (AD) poses a significant public health problem, affecting millions of people across the world. Despite decades of research into therapeutic strategies for AD, effective prevention or treatment for this devastating disorder remains elusive. In this review, we discuss the potential of photobiomodulation (PBM) for preventing and alleviating AD-associated pathologies, with a focus on the biological mechanisms underlying this therapy. Future research directions and guidance for clinical practice for this non-invasive and non-pharmacological therapy are also highlighted. The available evidence indicates that different treatment paradigms, including transcranial and systemic PBM, along with the recently proposed remote PBM, all could be promising for AD. PBM exerts diverse biological effects, such as enhancing mitochondrial function, mitigating the neuroinflammation caused by activated glial cells, increasing cerebral perfusion, improving glymphatic drainage, regulating the gut microbiome, boosting myokine production, and modulating the immune system. We suggest that PBM may serve as a powerful therapeutic intervention for AD.

Noninvasive Light Flicker Stimulation Promotes Optic Nerve Regeneration by Activating Microglia and Enhancing Neural Plasticity in Zebrafish

Purpose

Forty-hertz light flicker stimulation has been proven to reduce neurodegeneration, but its effect on optic nerve regeneration is unclear. This study explores the effect of 40-Hz light flicker in promoting optic nerve regeneration in zebrafish and investigates the underlying mechanisms.

Methods

Wild-type and mpeg1:EGFP zebrafish were used to establish a model of optic nerve crush. Biocytin tracing and hematoxylin and eosin staining were employed to observe whether 40-Hz light flicker promotes regeneration of retinal ganglion cell axons and dendrites. Optomotor and optokinetic responses were evaluated to assess recovery of visual function. Immunofluorescence staining of mpeg1:EGFP zebrafish was performed to observe changes in microglia. Differentially expressed genes that promote optic nerve regeneration following 40-Hz light flicker stimulation were identified and validated through RNA-sequencing analysis and quantitative real-time PCR (qRT-PCR).

Results

Zebrafish exhibited spontaneous optic nerve regeneration after optic nerve injury and restored visual function. We observed that 40-Hz light flicker significantly activated microglia following optic nerve injury and promoted regeneration of retinal ganglion cell axons and dendrites, as well as recovery of visual function. Transcriptomics and qRT-PCR analyses revealed that 40-Hz light flicker increased the expression of genes associated with neuronal plasticity, including bdnf, npas4a, fosab, fosb, egr4, and ier2a.

Conclusions

To our knowledge, this study is the first to demonstrate that 40-Hz light flicker stimulation promotes regeneration of retinal ganglion cell axons and dendrites and recovery of visual function in zebrafish, which is associated with microglial activation and enhancement of neural plasticity.

The neuroprotective effect of near infrared light therapy in aged mice with postoperative neurocognitive disorder by upregulating IRF7

BACKGROUND

Postoperative neurocognitive disorder (PND) is a common central nervous system complication after undergoing surgery and anesthesia especially in elderly patients, while the therapeutic options are very limited. This study was carried out to investigate the beneficial effects of transcranial near infrared light (NIRL) which was employed to the treatment of PND and propose the involved mechanisms.

METHODS

The PND mice were established through left carotid artery exposure under isoflurane anesthesia and received transcranial NIRL treatment. Behavioral testing was performed to evaluate the cognitive function of PND mice after transcranial NIRL therapy. Changes in the transcriptomic profiles of prefrontal cortex (PFC) and hippocampus (HP) were identified by next generation sequencing (NGS), and the molecular mechanisms involved were examined by both in vivo mouse model and in vitro cell culture studies.

RESULTS

We found that transcranial NIRL therapy effectively ameliorated learning and memory deficit induced by anesthesia and surgery in aged mice. Specifically, we identified down-regulation of interferon regulatory factor 7 (IRF7) in the brains of PND mice that was mechanistically associated with increased pro-inflammatory M1 phenotype of microglia and elevated neuroinflammatory. NIRL treatment produced protective effects through the upregulation of IRF7 expression and reversing microglial phenotypes from pro-inflammatory to neuroprotective, resulting in reduced brain damage and improved cognitive function in PND mice.

CONCLUSION

Our results indicate that transcranial NIRL is an effective and safe therapy for PND via alleviating neuroinflammation, and IRF7 plays a key transcription factor in regulating the M1-to-M2 switch of microglia.

Cognitive impairment in Alzheimer's disease FAD4T mouse model: Synaptic loss facilitated by activated microglia via C1qA

Alzheimer's disease (AD) is a chronic and progressive neurodegenerative disorder characterized by cognitive dysfunction. The connection between neuroinflammation and abnormal synaptic function in AD is recognized, but the underlying mechanisms remain unclear. In this study, we utilized a mouse model of AD, FAD4T mice aged 6-7 months, to investigate the molecular changes affecting cognitive impairment. Behavior tests showed that FAD4T mice exhibited impaired spatial memory compared with their wild-type littermates. Immunofluorescence staining revealed the presence of Aβ plaques and abnormal glial cell activation as well as changes in microglial morphology in the cortex and hippocampus of FAD4T mice. Synaptic function was impaired in FAD4T mice. Patch clamp recordings of hippocampal neurons revealed reduced amplitude of miniature excitatory postsynaptic currents. Additionally, Golgi staining showed decreased dendritic spine density in the cortex and hippocampus of FAD4T mice, indicating aberrant synapse morphology. Moreover, hippocampal PSD-95 and NMDAR1 protein levels decreased in FAD4T mice. RNA-seq analysis revealed elevated expression of immune system and proinflammatory genes, including increased C1qA protein and mRNA levels, as well as higher expression of TNF-α and IL-18. Taken together, our findings suggest that excessive microglia activation mediated by complement factor C1qA may contribute to aberrant synaptic pruning, resulting in synapse loss and disrupted synaptic transmission, ultimately leading to AD pathogenesis and behavioral impairments in the FAD4T mouse model. Our study provides valuable insights into the underlying mechanisms of cognitive impairments and preliminarily explores a potentially effective treatment approach targeting on C1qA for AD.

Phototherapy for age-related brain diseases: Challenges, successes and future

Brain diseases present a significant obstacle to both global health and economic progress, owing to their elusive pathogenesis and the limited effectiveness of pharmaceutical interventions. Phototherapy has emerged as a promising non-invasive therapeutic modality for addressing age-related brain disorders, including stroke, Alzheimer's disease (AD), and Parkinson's disease (PD), among others. This review examines the recent progressions in phototherapeutic interventions. Firstly, the article elucidates the various wavelengths of visible light that possess the capability to penetrate the skin and skull, as well as the pathways of light stimulation, encompassing the eyes, skin, veins, and skull. Secondly, it deliberates on the molecular mechanisms of visible light on photosensitive proteins, within the context of brain disorders and other molecular pathways of light modulation. Lastly, the practical application of phototherapy in diverse clinical neurological disorders is indicated. Additionally, this review presents novel approaches that combine phototherapy and pharmacological interventions. Moreover, it outlines the limitations of phototherapeutics and proposes innovative strategies to improve the treatment of cerebral disorders.

Photobiomodulation for Neurodegenerative Diseases: A Scoping Review

Neurodegenerative diseases involve the progressive dysfunction and loss of neurons in the central nervous system and thus present a significant challenge due to the absence of effective therapies for halting or reversing their progression. Based on the characteristics of neurodegenerative diseases such as Alzheimer's disease (AD) and Parkinson's disease (PD), which have prolonged incubation periods and protracted courses, exploring non-invasive physical therapy methods is essential for alleviating such diseases and ensuring that patients have an improved quality of life. Photobiomodulation (PBM) uses red and infrared light for therapeutic benefits and functions by stimulating, healing, regenerating, and protecting organizations at risk of injury, degradation, or death. Over the last two decades, PBM has gained widespread recognition as a non-invasive physical therapy method, showing efficacy in pain relief, anti-inflammatory responses, and tissue regeneration. Its application has expanded into the fields of neurology and psychiatry, where extensive research has been conducted. This paper presents a review and evaluation of studies investigating PBM in neurodegenerative diseases, with a specific emphasis on recent applications in AD and PD treatment for both animal and human subjects. Molecular mechanisms related to neuron damage and cognitive impairment are scrutinized, offering valuable insights into PBM's potential as a non-invasive therapeutic strategy.

A comprehensive review on therapeutic potentials of photobiomodulation for neurodegenerative disorders

A series of experimental trials over the past two centuries has put forth Photobiomodulation (PBM) as a treatment modality that utilizes colored lights for various conditions. While in its cradle, PBM was used for treating simple conditions such as burns and wounds, advancements in recent years have extended the use of PBM for treating complex neurodegenerative diseases (NDDs). PBM has exhibited the potential to curb several symptoms and signs associated with NDDs. While several of the currently used therapeutics cause adverse side effects alongside being highly invasive, PBM on the contrary, seems to be broad-acting, less toxic, and non-invasive. Despite being projected as an ideal therapeutic for NDDs, PBM still isn't considered a mainstream treatment modality due to some of the challenges and knowledge gaps associated with it. Here, we review the advantages of PBM summarized above with an emphasis on the common mechanisms that underlie major NDDs and how PBM helps tackle them. We also discuss important questions such as whether PBM should be considered a mainstay treatment modality for these conditions and if PBM's properties can be harnessed to develop prophylactic therapies for high-risk individuals and also highlight important animal studies that underscore the importance of PBM and the challenges associated with it. Overall, this review is intended to bring the major advances made in the field to the spotlight alongside addressing the practicalities and caveats to develop PBM as a major therapeutic for NDDs.

Transcranial photobiomodulation for brain diseases: review of animal and human studies including mechanisms and emerging trends

The brain diseases account for 30% of all known diseases. Pharmacological treatment is hampered by the blood-brain barrier, limiting drug delivery to the central nervous system (CNS). Transcranial photobiomodulation (tPBM) is a promising technology for treating brain diseases, due to its effectiveness, non-invasiveness, and affordability. tPBM has been widely used in pre-clinical experiments and clinical trials for treating brain diseases, such as stroke and Alzheimer's disease. This review provides a comprehensive overview of tPBM. We summarize emerging trends and new discoveries in tPBM based on over one hundred references published in the past 20 years. We discuss the advantages and disadvantages of tPBM and highlight successful experimental and clinical protocols for treating various brain diseases. A better understanding of tPBM mechanisms, the development of guidelines for clinical practice, and the study of dose-dependent and personal effects hold great promise for progress in treating brain diseases.

Exploring the effect of photobiomodulation and gamma visual stimulation induced by 808 nm and visible LED in Alzheimer's disease mouse model

Although photobiomodulation (PBM) and gamma visual stimulatqion (GVS) have been overwhelmingly explored in the recent time as a possible light stimulation (LS) means of Alzheimer's disease (AD) therapy, their effects have not been assessed at once. In our research, the AD mouse model was stimulated using light with various parameters [continuous wave (PBM) or 40 Hz pulsed visible LED (GVS) or 40 Hz pulsed 808 nm LED (PBM and GVS treatment)]]. The brain slices collected from the LS treated AD model mice were evaluated using (i) fluorescence microscopy to image thioflavine-S labeled amy-loid-β (Aβ) plaques (the main hallmark of AD), or (ii) two-photon excited fluorescence (TPEF) imaging of unlabeled Aβ plaques, showing that the amount of Aβ plaques was reduced after LS treatment. The imaging results correlated well with the results of Morris water maze (MWM) test, which demonstrated that the spatial learning and memory abilities of LS treated mice were noticeably higher than those of untreated mice. The LS effect was also assessed by in vivo nonlinear optical imaging, revealing that the cerebral amyloid angiopathy decreased spe-cifically as a result of 40 Hz pulsed 808 nm irradiation, on the contrary, the angiopathy reversed after visible 40 Hz pulsed light treatment. The obtained results provide useful reference for further optimization of the LS (PBM or GVS) parameters to achieve efficient phototherapy of AD.

Photostimulation of lymphatic clearance of β-amyloid from mouse brain: a new strategy for the therapy of Alzheimer's disease

Alzheimer's disease (AD) is an age-related neurodegenerative disorder that poses a significant burden on socio-economic and healthcare systems worldwide. However, the currently available therapy of AD is limited, and new strategies are needed to enhance the clearance of β-amyloid (Aβ) protein and improve cognitive function. Photobiomodulation (PBM) is a non-invasive and effective therapeutic method that has shown promise in treating various brain diseases. Here, we demonstrate that 1267-nm PBM significantly alleviates cognitive decline in the 5xFAD mouse model of AD and is safe as it does not induce a significant increase in cortical temperature. Moreover, with the combination of 3D tissue optical clearing imaging and automatic brain region segmentation, we show that PBM-mediated reductions of Aβ plaques in different subregions of prefrontal cortex and the hippocampus are different. The PBM-induced lymphatic clearance of Aβ from the brain is associated with improvement of memory and cognitive functions in 5xFAD mice. Our results suggest that the modulation of meningeal lymphatic vessels (MLVs) should play an important role in promoting Aβ clearance. Collectively, this pilot study demonstrates that PBM can safely accelerate lymphatic clearance of Aβ from the brain of 5xFAD mice, promoting improvement of neurocognitive status of AD animals suggesting that PBM can be an effective and bedside therapy for AD.

Transcranial photobiomodulation improves insulin therapy in diabetic microglial reactivity and the brain drainage system

The dysfunction of microglia in the development of diabetes is associated with various diabetic complications, while traditional insulin therapy is insufficient to rapidly restore the function of microglia. Therefore, the search for new alternative methods of treating diabetes-related dysfunction of microglia is urgently needed. Here, we evaluate the effects of transcranial photobiomodulation (tPBM) on microglial function in diabetic mice and investigate its mechanism. We find tPBM treatment effectively improves insulin therapy on microglial morphology and reactivity. We also show that tPBM stimulates brain drainage system through activation of meningeal lymphatics, which contributes to the removal of inflammatory factor, and increase of microglial purinergic receptor P2RY12. Besides, the energy expenditure and locomotor activity of diabetic mice are also improved by tPBM. Our results demonstrate that tPBM can be an efficient, non-invasive method for the treatment of microglial dysfunction caused by diabetes, and also has the potential to prevent diabetic physiological disorders.

Low-intensity pulsed ultrasound stimulation (LIPUS) modulates microglial activation following intracortical microelectrode implantation

Microglia are important players in surveillance and repair of the brain. Their activation mediates neuroinflammation caused by intracortical microelectrode implantation, which impedes the application of intracortical brain-computer interfaces (BCIs). While low-intensity pulsed ultrasound stimulation (LIPUS) can attenuate microglial activation, its potential to modulate the microglia-mediated neuroinflammation and enhance the bio-integration of microelectrodes remains insufficiently explored. We found that LIPUS increased microglia migration speed from 0.59±0.04 to 1.35±0.07 µm/hr on day 1 and enhanced microglia expansion area from 44.50±6.86 to 93.15±8.77 µm 2 /min on day 7, indicating improved tissue healing and surveillance. Furthermore, LIPUS reduced microglial activation by 17% on day 6, vessel-associated microglia ratio from 70.67±6.15 to 40.43±3.87% on day 7, and vessel diameter by 20% on day 28. Additionally, microglial coverage of the microelectrode was reduced by 50% in week 1, indicating better tissue-microelectrode integration. These data reveal that LIPUS helps resolve neuroinflammation around chronic intracortical microelectrodes.

Wearable and Wavelength-Tunable Near-Infrared Organic Light-Emitting Diodes for Biomedical Applications

Near-infrared organic light-emitting diodes (NIR OLEDs) have significant potential for wearable phototherapeutic applications because of the unique properties of the OLEDs, including their free-form electronics and the excellent biomedical effects of NIR emission. In spite of their tremendous promise, given that the majority of NIR OLEDs in previous research have relied on the utilization of an intrinsically brittle indium tin oxide (ITO) electrode, their practicality in the field of wearable electronics is inherently constrained. Here, we report wearable and wavelength-tunable NIR OLEDs that employ a high-performance NIR emitter and an innovative architecture by replacing the ITO with a silver (Ag) electrode. The NIR OLEDs permit wavelength tuning of emissions from 700 to 800 nm and afford stable operation even under repeated bending conditions. The NIR OLEDs provide a lowered device temperature of 37.5 °C even during continuous operation under several emission intensities. In vitro experiments were performed with freshly fabricated NIR OLEDs. The outcomes were evaluated against experimental results performed using the same procedure utilizing blue, green, and red OLEDs. When exposed to NIR light irradiation, the promoting effect of cell proliferation surpassed the proliferative responses observed under the influence of visible light irradiation. The proliferation effect of human hair follicle dermal papilla cells is clearly related to the irradiation wavelength and time, thus underscoring the potential of wavelength-tunable NIR OLEDs for efficacious phototherapy. This work will open novel avenues for wearable NIR OLEDs in the field of biomedical application.

A randomized, blinded study of photobiomodulation in a mouse model of Alzheimer's disease showed no preventive effect

Photobiomodulation (PBM), the process of exposing tissue to red or near-infrared light, has become a topic of great interest as a therapy for diverse pathologies, including neurodegenerative disorders. Here, we aimed to evaluate the potential beneficial effect of PBM on Alzheimer's disease (AD) using behavioral and histological readouts from a well-established transgenic murine AD model (5xFAD mice) in a randomized and fully blinded long-term in-vivo study following GLP (Good Laboratory Practices) guidelines. The heads of the mice were illuminated with no (sham), low or high power 810 nm light, three times a week for 5 months from the first to the sixth month of life corresponding to the prodromal phase of the pathology. The results showed that there were no significant differences between the groups in behavioral tests, including the Morris water maze, novel object recognition, and Y-maze. Similarly, histological analyses showed no differences in amyloid load, neuronal loss or microglial response. In conclusion, under the conditions of our experiment, we were unable to demonstrate any therapeutic effect of PBM for AD. This study calls for further evidence and caution when considering PBM as an effective treatment for AD.

Exosomes Derived from M2 Microglial Cells Modulated by 1070-nm Light Improve Cognition in an Alzheimer's Disease Mouse Model

Near-infrared photobiomodulation has been identified as a potential strategy for Alzheimer's disease (AD). However, the mechanisms underlying this therapeutic effect remain poorly characterize. Herein, it is illustrate that 1070-nm light induces the morphological alteration of microglia from an M1 to M2 phenotype that secretes exosomes, which alleviates the β-amyloid burden to improve cognitive function by ameliorating neuroinflammation and promoting neuronal dendritic spine plasticity. The results show that 4 J cm-2 1070-nm light at a 10-Hz frequency prompts microglia with an M1 inflammatory type to switch to an M2 anti-inflammatory type. This induces secretion of M2 microglial-derived exosomes containing miR-7670-3p, which targets activating transcription factor 6 (ATF6) during endoplasmic reticulum (ER) stress. Moreover, it is found that miR-7670-3p reduces ATF6 expression to further ameliorate ER stress, thus attenuating the inflammatory response and protecting dendritic spine integrity of neurons in the cortex and hippocampus of 5xFAD mice, ultimately leading to improvements in cognitive function. This study highlights the critical role of exosomes derive from 1070-nm light-modulated microglia in treating AD mice, which may provide a theoretical basis for the treatment of AD with the use of near-infrared photobiomodulation.

Current emerging novel therapies for Alzheimer's disease and the future prospects of magneto-mechanical force therapy

Alzheimer's disease (AD) is the most common neurodegenerative disease among the elderly, and the morbidity increases with the aging population aggravation. The clinical symptoms of AD mainly include cognitive impairment and memory loss, which undoubtedly bring a huge burden to families and society. Currently, the drugs in clinical use only improve the symptoms of AD but do not cure or prevent the progression of the disease. Therefore, it is urgent for us to develop novel therapeutic strategies for effective AD treatment. To provide a better theoretical basis for exploring novel therapeutic strategies in future AD treatment, this review introduces the recent AD treatment technologies from three aspects, including nanoparticle (NP) based drug therapy, biological therapy and physical therapy. The nanoparticle-mediated therapeutic approaches at the nanomaterial-neural interface and biological system are described in detail, and in particular the magneto-regulated strategies by magnetic field actuating magnetic nanoparticles are highlighted. Promising application of magneto-mechanical force regulated strategy in future AD treatment is also addressed, which offer possibilities for the remote manipulation in a precise manner. In the future, it may be possible for physicians to realize a remote, precise and effective therapy for AD using magneto-mechanical force regulated technology based on the combination of magnetic nanoparticles and an external magnetic field.

Functional material-mediated wireless physical stimulation for neuro-modulation and regeneration

Nerve injuries and neurological diseases remain intractable clinical challenges. Despite the advantages of stem cell therapy in treating neurological disorders, uncontrollable cell fates and loss of cell function in vivo are still challenging. Recently, increasing attention has been given to the roles of external physical signals, such as electricity and ultrasound, in regulating stem cell fate as well as activating or inhibiting neuronal activity, which provides new insights for the treatment of neurological disorders. However, direct physical stimulations in vivo are short in accuracy and safety. Functional materials that can absorb energy from a specific physical field exerted in a wireless way and then release another localized physical signal hold great advantages in mediating noninvasive or minimally invasive accurate indirect physical stimulations to promote the therapeutic effect on neurological disorders. In this review, the mechanism by which various physical signals regulate stem cell fate and neuronal activity is summarized. Based on these concepts, the approaches of using functional materials to mediate indirect wireless physical stimulation for neuro-modulation and regeneration are systematically reviewed. We expect that this review will contribute to developing wireless platforms for neural stimulation as an assistance for the treatment of neurological diseases and injuries.

Photostimulation of brain lymphatics in male newborn and adult rodents for therapy of intraventricular hemorrhage

Intraventricular hemorrhage is one of the most fatal forms of brain injury that is a common complication of premature infants. However, the therapy of this type of hemorrhage is limited, and new strategies are needed to reduce hematoma expansion. Here we show that the meningeal lymphatics is a pathway to remove red blood cells from the brain's ventricular system of male human, adult and newborn rodents and is a target for non-invasive transcranial near infrared photobiomodulation. Our results uncover the clinical significance of phototherapy of intraventricular hemorrhage in 4-day old male rat pups that have the brain similar to a preterm human brain. The course of phototherapy in newborn rats provides fast recovery after intraventricular hemorrhage due to photo-improvements of lymphatic drainage and clearing functions. These findings shed light on the mechanisms of phototherapy of intraventricular hemorrhage that can be a clinically relevant technology for treatment of neonatal intracerebral bleedings.

Microglia in neurodegenerative diseases: mechanism and potential therapeutic targets

Microglia activation is observed in various neurodegenerative diseases. Recent advances in single-cell technologies have revealed that these reactive microglia were with high spatial and temporal heterogeneity. Some identified microglia in specific states correlate with pathological hallmarks and are associated with specific functions. Microglia both exert protective function by phagocytosing and clearing pathological protein aggregates and play detrimental roles due to excessive uptake of protein aggregates, which would lead to microglial phagocytic ability impairment, neuroinflammation, and eventually neurodegeneration. In addition, peripheral immune cells infiltration shapes microglia into a pro-inflammatory phenotype and accelerates disease progression. Microglia also act as a mobile vehicle to propagate protein aggregates. Extracellular vesicles released from microglia and autophagy impairment in microglia all contribute to pathological progression and neurodegeneration. Thus, enhancing microglial phagocytosis, reducing microglial-mediated neuroinflammation, inhibiting microglial exosome synthesis and secretion, and promoting microglial conversion into a protective phenotype are considered to be promising strategies for the therapy of neurodegenerative diseases. Here we comprehensively review the biology of microglia and the roles of microglia in neurodegenerative diseases, including Alzheimer's disease, Parkinson's disease, multiple system atrophy, amyotrophic lateral sclerosis, frontotemporal dementia, progressive supranuclear palsy, corticobasal degeneration, dementia with Lewy bodies and Huntington's disease. We also summarize the possible microglia-targeted interventions and treatments against neurodegenerative diseases with preclinical and clinical evidence in cell experiments, animal studies, and clinical trials.

Preventing Post-Traumatic Stress Disorder (PTSD) in rats with pulsed 810 nm laser transcranial phototherapy

Post-traumatic stress disorder (PTSD) is a debilitating condition that occurs following exposure to traumatic events. Current treatments, such as psychological debriefing and pharmacotherapy, often have limited efficacy and may result in unwanted side effects, making early intervention is a more desirable strategy. In this study, we investigated the efficacy of a single dose of pulsed (10 Hz) 810 nm laser-phototherapy (P-PT) as an early intervention for preventing PTSD-like comorbidities in rats induced by single inescapable electric foot shock following the single prolonged stress (SPS&S). As indicated by the results of the open filed test, elevated plus maze test, and contextual fear conditioning test, P-PT prevented the development of anxiety and freezing behaviors in rats exposed to the SPS&S. We also compared the effects of P-PT and continuous wave 810 nm laser-phototherapy (CW-PT) in preventing PTSD-like comorbidities in rats. The results revealed that P-PT was effective in preventing both freezing and anxiety behavior in stressed rats. In contrast, CW-PT only had a preventive effect on freezing behavior but not anxiety. Additionally, P-PT significantly reduced the c-fos expression in cingulate cortex area 1(Cg1) and infralimbic cortex (IL) of stressed rats, while CW-PT had no significant effects on c-fos expression. Taken together, our results demonstrate that P-PT is a highly effective strategy for preventing the occurrence of PTSD-like comorbidities in rats.

Brain Waste Removal System and Sleep: Photobiomodulation as an Innovative Strategy for Night Therapy of Brain Diseases

Emerging evidence suggests that an important function of the sleeping brain is the removal of wastes and toxins from the central nervous system (CNS) due to the activation of the brain waste removal system (BWRS). The meningeal lymphatic vessels (MLVs) are an important part of the BWRS. A decrease in MLV function is associated with Alzheimer's and Parkinson's diseases, intracranial hemorrhages, brain tumors and trauma. Since the BWRS is activated during sleep, a new idea is now being actively discussed in the scientific community: night stimulation of the BWRS might be an innovative and promising strategy for neurorehabilitation medicine. This review highlights new trends in photobiomodulation of the BWRS/MLVs during deep sleep as a breakthrough technology for the effective removal of wastes and unnecessary compounds from the brain in order to increase the neuroprotection of the CNS as well as to prevent or delay various brain diseases.

Red-light radiation: does it enhance memory by increasing hippocampal LRP-1 and TRPA-1 genes expression?

PURPOSE

Despite the extensive efforts to treat the leading cause of neurodegenerative diseases (ND), a little progress has been reported. Red light might affect ND through many specific mechanisms. The purpose of this investigation is to explore the effect of red light on the expression of low-density lipoprotein receptor-1 (LRP-1) and transient receptor potential ankyrin-1 (TRPA-1) gene in the hippocampus, and the serum melatonin level (SML) of the lipopolysaccharide (LPS)-induced neuro-inflammated rats.

MATERIALS AND METHODS

Red-light therapy was implemented using a wavelength 630 nm under different light conditions and the passive avoidance (PA) and Y-Maze tests were employed to assess memory performance. To evaluate the LRP-1 and TRPA-1 genes expression, quantitive real-time polymerase chain reaction was performed. To measure the SML, ELISA was performed before and after the red-light radiation.

RESULTS

LPS caused memory impairment in both behavioral tests. Red-light therapy improved PA memory in all light conditions (p < .001). However, in Y-maze, only the red-light radiation during light and dark cycles, improved memory (p < .01 and p < .001, respectively). In addition, red-light radiation caused significant increase in SML (p < .05). The LRP-1 and TRPA-1 genes expression increased significantly during the dark phase in the red light radiated group compared to non-radiated group (p < .001).

CONCLUSIONS

Taken together, the results suggest that red-light therapy can reduce the complications of memory impairment in rats. This study has found that red-light therapy demonstrates higher effect during the period of dark phase compared to light phase. No doubt, further experimental studies would help us to establish a greater degree of accuracy on this matter.

Transcranial near-infrared laser improves postoperative neurocognitive disorder in aged mice via SIRT3/AMPK/Nrf2 pathway

Background

Postoperative neurocognitive disorder (PND) is a common central nervous system (CNS) complication that might increase the morbidity and mortality of elderly patients after anesthesia/surgery. Neuroinflammation, oxidative stress, and synaptic dysfunction are closely related to cognitive dysfunction, an important clinical feature of PND. Transcranial near-infrared laser (TNIL) is regarded as an effective treatment for cognitive-related diseases by improving mitochondrial function and alleviating neuroinflammation and oxidative stress damage.

Materials and methods

Aged male C57BL/6 mice underwent a carotid artery exposure procedure under isoflurane anesthesia. We treated PND-aged mice for three consecutive days (4 h post-operation, 1-laser) with 810 nm continuous wave (CW) laser 18 J/cm² at 120 mW/cm². The post-treatment evaluation included behavioral tests, RTq-PCR, immunofluorescence, and Western blot.

Results

The results demonstrated that TNIL improved PND and the levels of synaptic function-associated proteins such as post-synaptic density protein 95 (PSD95), synaptophysin (SYP), and brain-derived neurotrophic factor (BDNF). Besides, neuroinflammatory cytokine levels of tumor necrosis factor (TNF)-α and interleukin (IL)-1β as well as microglia activation and oxidative stress damage were attenuated after TNIL treatment in aged mice with PND. Further investigation suggested that TNIL relieved oxidative stress response by activating the SIRT3/AMPK/Nrf2 pathway.

Conclusion

Transcranial near-infrared laser improved cognitive impairment in aged mice with PND, which may be a promising therapeutic for PND.