Luteolin Inhibits Fibrillary β-Amyloid1-40-Induced Inflammation in a Human Blood-Brain Barrier Model by Suppressing the p38 MAPK-Mediated NF-κB Signaling Pathways

Luteolin protects against testicular injury induced by lead acetate by activating the Nrf2/HO-1 pathway

Lead (Pb) is a toxic heavy metal that is harmful to humans, especially male reproductive organs. Luteolin (LUT) is a naturally occurring flavonoid with numerous biological activities. Our aim was to investigate the possible reproprotective effect of LUT against testicular deficits induced by Pb intoxication. In the present study, 28 rats were distributed into 4 groups: control, LUT (50 mg/kg), lead acetate (PbAc, 20 mg/kg), and LUT + PbAc groups, in which rats were pre-treated with LUT 3 hr before PbAc injection. All animals were treated for 7 days. Oxidative stress, inflammatory and apoptotic markers along with histopathological changes have been examined using spectrophotometric, ELISA, real-time PCR, and histopathological methods. PbAc injection elevated Pb concentration in testicular tissue and decreased levels of sex hormones. PbAc intoxication exacerbated lipoperoxidation and nitric oxide formation, depleted superoxide dismutase, and catalase activities along with glutathione and its originated enzymes (glutathione peroxidase and glutathione reductase). At the molecular level, PbAc deactivated nuclear factor erythroid 2-related factor 2 and heme oxygenase-1 in the testicular tissue. In addition, PbAc toxicity induced inflammatory and apoptotic cascades in testicular tissue as evidenced by the increased tumor necrosis factor-alpha, interleukin-1 beta, inducible nitric oxide synthase, Bax, and caspase 3, while Bcl-2 was declined. Histopathological examination of testicular tissue also revealed that PbAc caused degeneration alterations in spermatogenic cells, the spermatogenic epithelial cells were disconnected from the basement membrane, and the seminiferous tubules were vacuolated. Remarkably, pre-treatment with LUT minimized significantly the testicular damage induced by PbAc. Therefore, we conclude that LUT may have a beneficial effect against PbAc-induced testicular injury through preventing oxidative challenge, inflammation, and finally apoptosis.

Luteolin alleviates neuroinflammation via downregulating the TLR4/TRAF6/NF-κB pathway after intracerebral hemorrhage

The activation of microglia and inflammatory responses is essential for the process of intracerebral hemorrhage (ICH)-induced secondary brain injury (SBI). In this study, we investigated the effects of luteolin on ICH-induced SBI and the potential mechanisms. Autologous blood was injected to establish the ICH model in vivo, and oxyhemoglobin (OxyHb) was used to mimic the ICH model in vitro. We found that the administration of luteolin significantly improved motor and sensory impairments and inhibited neuronal cell degeneration in vivo. In the in vitro study, the decrease of the neuronal cell viability induced by activated microglia was alleviated by luteolin treatment. Furthermore, by antagonizing the activation of the Toll-like receptor 4 (TLR4)/TNF receptor-associated factor 6 (TRAF6)/nuclear transcription factor-κB (NF-κB) signaling pathway, the ICH-induced elevation of cytokine release was decreased after treatment with luteolin, which was confirmed both in vivo and in vitro. Additionally, we found that luteolin engaged with TRAF6 and inhibited the ubiquitination of TRAF6. Taken together, our findings demonstrate the neuroprotective effects of luteolin after ICH and the potential mechanisms, which suggest that luteolin is a potential therapeutic candidate for ICH treatment.

Luteolin Exerts Neuroprotection via Modulation of the p62/Keap1/Nrf2 Pathway in Intracerebral Hemorrhage

Upregulation of neuronal oxidative stress is involved in the progression of secondary brain injury (SBI) following intracerebral hemorrhage (ICH). In this study, we investigated the potential effects and underlying mechanisms of luteolin on ICH-induced SBI. Autologous blood and oxyhemoglobin (OxyHb) were used to establish in vivo and in vitro models of ICH, respectively. Luteolin treatment effectively alleviated brain edema and ameliorated neurobehavioral dysfunction and memory loss in vivo. Also, in vivo, we found that luteolin promoted the activation of the sequestosome 1 (p62)/kelch‐like enoyl-coenzyme A hydratase (ECH)‐associated protein 1 (Keap1)/nuclear factor erythroid 2-related factor 2 (Nrf2) pathway by enhancing autophagy and increasing the translocation of Nrf2 to the nucleus. Meanwhile, luteolin inhibited the ubiquitination of Nrf2 and increased the expression levels of downstream antioxidant proteins, such as heme oxygenase-1 (HO-1) and reduced nicotinamide adenine dinucleotide phosphate (NADPH): quinine oxidoreductase 1 (NQO1). This effect of luteolin was also confirmed in vitro, which was reversed by the autophagy inhibitor, chloroquine (CQ). Additionally, we found that luteolin inhibited the production of neuronal mitochondrial superoxides (MitoSOX) and alleviated neuronal mitochondrial injury in vitro, as indicated via tetrachloro-tetraethylbenzimidazol carbocyanine-iodide (JC-1) staining and MitoSOX staining. Taken together, our findings demonstrate that luteolin enhances autophagy and anti-oxidative processes in both in vivo and in vitro models of ICH, and that activation of the p62-Keap1-Nrf2 pathway, is involved in such luteolin-induced neuroprotection. Hence, luteolin may represent a promising candidate for the treatment of ICH-induced SBI.

Sleep Promoting Effect of Luteolin in Mice via Adenosine A1 and A2A Receptors

Luteolin, a widespread flavonoid, has been known to have neuroprotective activity against various neurologic diseases such as epilepsy, and Alzheimer’s disease. However, little information is available regarding the hypnotic effect of luteolin. In this study, we evaluated the hypnotic effect of luteolin and its underlying mechanism. In pentobarbital-induced sleeping mice model, luteolin (1, and 3 mg/kg, p.o.) decreased sleep latency and increased the total sleep time. Through electroencephalogram (EEG) and electromyogram (EMG) recording, we demonstrated that luteolin increased non-rapid eye movement (NREM) sleep time and decreased wake time. To evaluate the underlying mechanism, we examined the effects of various pharmacological antagonists on the hypnotic effect of luteolin. The hypnotic effect of 3 mg/kg of luteolin was not affected by flumazenil, a GABAA receptor-benzodiazepine (GABAAR-BDZ) binding site antagonist, and bicuculine, a GABAAR-GABA binding site antagonist. On the other hand, the hypnotic effect of 3 mg/kg of luteolin was almost completely blocked by caffeine, an antagonist for both adenosine A1 and A2A receptor (A1R and A2AR), 8-Cyclopentyl-1,3-dipropylxanthine (DPCPX), an A1R antagonist, and SCH-58261, an A2AR antagonist. From the binding affinity assay, we have found that luteolin significantly binds to not only A1R but also A2AR with IC₅₀ of 1.19, 0.84 μg/kg, respectively. However, luteolin did not bind to either BDZ-receptor or GABAAR. From these results, it has been suggested that luteolin has hypnotic efficacy through A1R and A2AR binding.

Transforming growth factor-β promotes basement membrane fibrosis, alters perivascular cerebrospinal fluid distribution, and worsens neurological recovery in the aged brain after stroke

Aging and stroke alter the composition of the basement membrane and reduce the perivascular distribution of cerebrospinal fluid and solutes, which may contribute to poor functional recovery in elderly patients. Following stroke, TGF-β induces astrocyte activation and subsequent glial scar development. This is dysregulated with aging and could lead to chronic, detrimental changes within the basement membrane. We hypothesized that TGF-β induces basement membrane fibrosis after stroke, leading to impaired perivascular CSF distribution and poor functional recovery in aged animals. We found that CSF entered the aged brain along perivascular tracts; this process was reduced by experimental stroke and was rescued by TGF-β receptor inhibition. Brain fibronectin levels increased with experimental stroke, which was reversed with inhibitor treatment. Exogenous TGF-β stimulation increased fibronectin expression, both in vivo and in primary cultured astrocytes. Oxygen-glucose deprivation of cultured astrocytes induced multiple changes in genes related to astrocyte activation and extracellular matrix production. Finally, in stroke patients, we found that serum TGF-β levels correlated with poorer functional outcomes, suggesting that serum levels may act as a biomarker for functional recovery. These results support a potential new treatment strategy to enhance recovery in elderly stroke patients.

Amyloid Beta 25-35 induces blood-brain barrier disruption in vitro

The amyloid β-peptide (Aβ) is transported across the blood-brain barrier (BBB) by binding with the receptor for advanced glycation end products (RAGE). Previously, we demonstrated that the Aβ fraction 25-35 (Aβ_25-35) increases RAGE expression in the rat hippocampus, likely contributing to its neurotoxic effects. However, it is still debated if the interaction of Aβ with RAGE compromises the BBB function in Alzheimer' disease (AD). Here, we evaluated the effects of Aβ_25-35 in an established in vitro model of the BBB. Rat brain microvascular endothelial cells (rBMVECs) were treated with 20 μM active Aβ_25-35 or the inactive Aβ_35-25 (control), for 24 h. Exposure to Aβ_25-35 significantly decreased cell viability, increased cellular necrosis, and increased the production of reactive oxygen species (ROS), which triggered a decrease in the enzyme glutathione peroxidase when compared to the control condition. Aβ_25-35 also increased BBB permeability by altering the expression of tight junction proteins (decreasing zonula occludens-1 and increasing occludin). Aβ_25-35 induced monolayer disruption and cellular disarrangement of the BBB, with RAGE being highly expressed in the zones of disarrangement. Together, these data suggest that Aβ_25-35-induces toxicity by compromising the functionality and integrity of the BBB in vitro. Graphical abstract Aβ_25-35 induces BBB dysfunction in vitro, wich is likely mediated by OS and ultimately leads to disruption of BBB integrity and cell death.

Luteolin Partially Inhibits LFA-1 Expression in Neutrophils Through the ERK Pathway

Luteolin inhibits the adhesion of neutrophils to microvascular endothelial cells and plays an important anti-inflammatory role, owing to its mechanism of suppressing the expression of lymphocyte function-associated antigen-1 (LFA-1) in the neutrophils. Our study deals with the different signaling pathways participating in LFA-1 expression in neutrophils along with the regulation of luteolin in order to elucidate new anti-inflammatory targets of luteolin, thus providing a basis for clinical applications. In our study, neutrophils were separated using density gradient centrifugation and the cAMP levels were determined using ELISA. Additionally, phosphorylation levels of p38 mitogen-activated protein kinase (MAPK), extracellular regulated protein kinase (ERK), phosphatidylinositol-3-kinase (PI3K), and Janus kinase (JAK) were also detected by Western blotting. LFA-1 expression was estimated using flow cytometry. The results showed that inhibiting agents used against p38 MAPK, ERK, PI3K, and JAK could significantly inhibit LFA-1 expression on neutrophils (p < 0.05, p < 0.01). Luteolin also induced a noteworthy elevation of cAMP in neutrophil supernatants (p < 0.01). It could also significantly inhibit ERK phosphorylation (p < 0.05, p < 0.01), and had no obvious effect on p38 MAPK phosphorylation in neutrophils (p > 0.05). However, phosphorylation of PI3K and JAK was not detected in neutrophils. To conclude, the p38 MAPK, ERK, PI3K, and JAK pathways are involved in the regulation of LFA-1 expression in neutrophils, and luteolin partially inhibits LFA-1 expression by increasing cAMP levels and suppressing ERK phosphorylation.

Natural Compounds for Alzheimer's Disease Therapy: A Systematic Review of Preclinical and Clinical Studies

Alzheimer's Disease (AD) is a neurodegenerative disorder related with the increase of age and it is the main cause of dementia in the world. AD affects cognitive functions, such as memory, with an intensity that leads to several functional losses. The continuous increase of AD incidence demands for an urgent development of effective therapeutic strategies. Despite the extensive research on this disease, only a few drugs able to delay the progression of the disease are currently available. In the last years, several compounds with pharmacological activities isolated from plants, animals and microorganisms, revealed to have beneficial effects for the treatment of AD, targeting different pathological mechanisms. Thus, a wide range of natural compounds may play a relevant role in the prevention of AD and have proven to be efficient in different preclinical and clinical studies. This work aims to review the natural compounds that until this date were described as having significant benefits for this neurological disease, focusing on studies that present clinical trials.

Ameliorative effect of supercritical fluid extract of Chrysanthemum indicum Linnén against D-galactose induced brain and liver injury in senescent mice via suppression of oxidative stress, inflammation and apoptosis

ETHNOPHARMACOLOGICAL RELEVANCE

Chrysanthemum indicum Linne (C. indicum), a healthy food and folk medicine in China for thousands of years, has been reported to exert heat-clearing and detoxifying effects and extensively applied to treat various symptoms such as inflammation diseases, hepatitis and headache.

AIM OF THIS STUDY

The purpose of the present study was to investigate the protective effect of the supercritical carbon dioxide fluid extract from flowers and buds of C. indicum (CI_SCFE) on D-galactose-induced brain and liver damage during aging process and to illuminate the underlying mechanisms.

MATERIALS AND METHODS

Mice were orally administrated with CI_SCFE (100, 150 and 300 mg/kg) after injection with D-galactose. 24 h after the last administration, the blood samples, whole brain and liver tissues were collected for biochemical analysis, histological examination and western blot analysis. The body weight, spleen and thymus indexes, alanine transaminase (ALT), aspartate transaminase (AST), total antioxidant capacity (T-AOC), superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GSH-Px), malondialdehyde (MDA) in brain and liver, interleukin-1β (IL-1β), interleukin-6 (IL-6), and necrosis factor-α (TNF-α) were detected. Besides, the expressions of Bax, Bcl-2 and cleaved caspase-3 were determined by western blot assay.

RESULTS

The results indicated that CI_SCFE effectively increased the suppressed body weight, attenuated the decline of thymus and spleen indexes, and reduced the elevated levels of ALT and AST induced by D-gal. Furthermore, CI_SCFE might notably alleviate D-gal-induced abnormal alterations in structure and function of brain and liver dose-dependently via renewing normal antioxidant enzymes activities (SOD, CAT, GSH-Px), reducing MDA accumulation, decreasing inflammatory cytokines productions (IL-1β, IL-6, TNF-α), as well as attenuating the increase of Bax/Bcl-2 ratio and cleaved caspase-3 activation in the liver and brain.

CONCLUSIONS

Taken together, our present results suggested that CI_SCFE treatment could effectively mitigate the D-gal-induced hepatic and cerebral injury, and the underlying mechanism might be tightly related to the decreased oxidative stress, inflammation and apoptosis, indicating CI_SCFE might be an alternative and promising agent for the treatment of aging and age-associated brain and liver diseases.

Pomegranate peel polyphenols inhibits inflammation in LPS-induced RAW264.7 macrophages via the suppression of TLR4/NF-κB pathway activation

BACKGROUNDS

Inflammatory response mediated by activated immune cells is a vital process in host defense system while responding to various stresses. Our previous studies have indicated that pomegranate peel polyphenols (PPPs) and their main components punicalagin (PC) and ellagic acid (EA) decreased pro-inflammatory cytokines and inflammatory mediators by regulating the mitogen-activated protein kinases (MAPKs) pathway, but whether these tested polyphenols play an important role in NF-κB signaling pathway, another crucial pathway of inflammation, remains unclear.

OBJECTIVE

In this study, we analyzed the anti-inflammatory effect of these polyphenols via TLR4-NF-κB pathway in lipopolysaccharide (LPS)-induced RAW264.7 macrophages.

METHODS

Different concentrations of PPPs, PC, and EA were pre-incubated with RAW264.7 macrophages and then stimulated with LPS (1 μg/mL), and the effects of reactive oxygen species and TLR4 were investigated. Moreover, NF-κB p65 nuclear translocation and phosphorylation, and degradation of IκB were measured by Western blot. Furthermore, the influence of pro-inflammatory cytokines was detected by enzyme-linked immunosorbent assay (ELISA).

RESULTS

Our data showed that PPPs, PC, and EA inhibited LPS-induced intracellular ROS production and suppressed the mRNA and protein expression levels of TLR4 in a dose-dependent manner. Moreover, the anti-inflammatory mechanism was involved in blocking LPS-induced phosphorylation, degradation of IκB, and nuclear translocation of p65. Additionally, PPPs and PC exhibited a stronger anti-inflammatory effect than that of EA.

CONCLUSION

The results indicated that PPPs possess potent anti-inflammatory effect, and PC was the main effective component in PPPs, which provided new insights into the utilization of PPPs to prevent inflammation-associated disorders.

Anti-inflammatory effects of luteolin: A review of in vitro, in vivo, and in silico studies

ETHNOPHARMACOLOGICAL RELEVANCE

Luteolin (3', 4', 5,7-tetrahydroxyflavone) has been identified as commonly present in plants. Plants with a high luteolin content have been used ethnopharmacologically to treat inflammation-related symptoms. Both isolated luteolin and extracts from luteolin-rich plants have been studied using various models and exhibited anti-inflammatory activity.

AIM OF THE REVIEW

This paper uses recent research findings with a broad range of study models to describe the anti-inflammatory activity of luteolin, particularly its mechanisms at the molecular level; provide guidance for future research; and evaluate the feasibility of developing luteolin into an anti-inflammatory drug.

MATERIALS AND METHODS

We summarize reports about the anti-inflammatory activity of luteolin published since 2009, which we found in MEDLINE/PubMed, Scopus, Web of Knowledge, and Google Scholar. To acquire broad information, we extended our search to online FDA documents.

RESULTS

Luteolin is a flavonoid commonly found in medicinal plants and has strong anti-inflammatory activity in vitro and in vivo. Some of its derivatives, such as luteolin-7-O-glucoside, have also shown anti-inflammatory activity. The action mechanism of luteolin varies, but Src in the nuclear factor (NF)-κB pathway, MAPK in the activator protein (AP)- 1 pathway, and SOCS3 in the signal transducer and activator of transcription 3 (STAT3) pathway are its major target transcription factors. A clinical trial with a formulation containing luteolin showed excellent therapeutic effect against inflammation-associated diseases.

CONCLUSION

In silico, in vitro, in vivo, and clinical studies strongly suggest that the major pharmacological mechanism of luteolin is its anti-inflammatory activity, which derives from its regulation of transcription factors such as STAT3, NF-κB, and AP-1. Much work remains to ensure the safety, quality, and efficacy of luteolin before it can be used to treat inflammation-related diseases in humans.

Epigallocatechin Gallate Reduces Amyloid β-Induced Neurotoxicity via Inhibiting Endoplasmic Reticulum Stress-Mediated Apoptosis

SCOPE

We investigated the role of endoplasmic reticulum (ER) stress in the protective effects of EGCG against the neuronal apoptosis in Aβ_1-42 -induced SH-SY5Y cells and APP/PS1 transgenic mice.

METHODS AND RESULTS

Cell viability (CCK8 assay), flow cytometry, Hoechst 33258 staining, immunohistochemistry, transmission electron microscopy (TEM), and western blotting were used. EGCG prevented Aβ1-42-induced toxicity in SH-SY5Y cells, increased cell viability, and decreased apoptosis in a dose-dependent manner. In a subsequent mechanism study, it was found that this effect contributed to the down-regulation of GRP78, CHOP, cleaved-caspase-12 and -3. Moreover, EGCG also reduced the cytotoxicity induced by tunicamycin (TM) and thapsigargin (TG), two ER stress activators. Consistent with the in vitro study, EGCG inhibited neuronal apoptosis in the cortex of APP/PS1 transgenic mice, with the mitigation of ER abnormal ultrastructural swelling and the downregulation of ER-stress-associated proteins.

CONCLUSION

These results indicate that EGCG attenuates the neurotoxicity in Alzheimer's disease (AD) via a novel mechanism that involves inhibition of ER-stress-associated neuronal apoptosis in vitro and in vivo, suggesting the tremendous potential of EGCG for use in a nutritional preventive strategy against AD.

Chitosan oligosaccharide ameliorates acute lung injury induced by blast injury through the DDAH1/ADMA pathway

Objective

To investigate the protective effect of chitosan oligosaccharide (COS) on acute lung injury (ALI) caused by blast injury, and explore possible molecular mechanisms.

Methods

A mouse model of blast injury-induced ALI was established using a self-made explosive device. Thirty mice were randomly assigned to control, ALI and ALI + COS groups. An eight-channel physiological monitor was used to determine the mouse physiological index. Enzyme linked immunosorbent assay was used to measure serum inflammatory factors. Hematoxylin-eosin staining, terminal deoxynucleotidyl transferase dUTP nick end labeling assay, immunofluorescence staining, real time-polymerase chain reaction and western blot assay were used to detect inflammatory reactions, oxidative stress and apoptosis.

Results

Mice were sacrificed 24 hours after successful model induction. Compared with the ALI group, the heart rate, respiration and PCO₂ were significantly lower, but the PO₂, TCO₂ and HCO₃^- were significantly higher in the ALI + COS group. Compared to ALI alone, COS treatment of ALI caused a significant decrease in the wet/dry lung weight ratio, indicating a reduction in lung edema, inflammatory cell infiltration, levels of tumor necrosis factor-α, interleukin (IL)-1β, IL-4, IL-6 and nuclear factor kappa B mRNA and protein expression were reduced and IL-10 mRNA and protein expression was increased (P < 0.05). COS significantly inhibited reactive oxygen species, MDA5 and IREα mRNA and protein expressions, cell apoptosis and Bax and Caspase-3 mRNA and protein expressions, and significantly increased superoxide dismutase-1 mRNA expression, and Bcl-2 and Caspase-8 mRNA and protein expression (all P<0.05). COS significantly increased dimethylarginine dimethylaminohydrolase 1 (DDAH1) protein expression, and reduced ADMA and p38 protein expression (P< 0.05).

Conclusion

Blast injury causes inflammation, oxidative stress and apoptosis in the lung tissues of mice. COS has protective effects on blast injury-induced ALI, possibly by promoting DDAH1 expression and inhibiting ADMA and mitogen-activated protein kinase pathways.

Asiaticoside Attenuates Cell Growth Inhibition and Apoptosis Induced by Aβ1-42 via Inhibiting the TLR4/NF-κB Signaling Pathway in Human Brain Microvascular Endothelial Cells

Alzheimer's disease (AD) is a very common progressive neurodegenerative disorder with the highest incidence in the world. Dysfunction of the blood-brain barrier (BBB) may be responsible for the pathogenesis and pathology of AD for abnormally transporting amyloid-β (Aβ, the main component of the senile plaques) from the sera into the central nervous system. Aβ peptides induce apoptosis in human brain microvascular endothelial cells (hBMECs), the main component of BBB. Apoptosis in neuronal cells plays a critical role in the pathogenesis of AD. Asiaticoside, a natural glycoside extracted from Centella asiatica (L.) Urban, has an anti-apoptotic effect on hBMECs but the molecule mechanism remains unclear. Therefore, we investigate the protective effect of asiaticoside on Aβ_1-42-induced cytotoxicity and apoptosis as well as associated mechanism in hBMECs with commonly used in vitro methods for clinical development of asiaticoside as a novel anti-AD agent. In the present study, we investigated the effects of asiaticoside on cytotoxicity by Cell Counting Kit-8 assay, mitochondrial membrane potential by JC-1 fluorescence analysis, anti-apoptosis by Hoechst 33258 staining and Annexin V-FITC (fluorescein isothiocyanate) and propidium iodide (PI) analyses, the expressions of TNF-α and IL-6 by enzyme-linked immunosorbent assay (ELISA) and TLR4, MyD88, TRAF6, p-NF-κB p65, and total NF-κB p65 by Western blotting, and nuclear translocation of NF-κB p65 by immunofluorescence analysis in hBMECs. The results showed that pretreatment of asiaticoside (25, 50, and 100 μM) for 12 h significantly attenuated cell growth inhibition and apoptosis, and restored declined mitochondrial membrane potential induced by Aβ_1-42 (50 μM) in hBMECs. Asiaticoside also significantly downregulated the elevated expressions of TNF-α, IL-6, TLR4, MyD88, TRAF6, and p-NF-κB p65, as well as inhibited NF-κB p65 translocation from cytoplasm to nucleus induced by Aβ_1-42 in hBMECs in a concentration-dependent manner. The possible underlying molecular mechanism of asiaticoside may be through inhibiting the TLR4/NF-κB signaling pathway. Therefore, asiaticoside may be developed as a novel agent for the prevention and/or treatment of AD clinically.

LED enhances anti-inflammatory effect of luteolin (3',4',5,7-tetrahydroxyflavone) in vitro

Neuroinflammation is a complex pathological process usually results from abnormal microglial activation, thus, intervention in a microglial stimulation pathway could be a promising approach for the treatment of neurodegenerative diseases. Luteolin is an important bioflavonoid possesses anti-inflammatory properties, which is widely studied over these years. Light emitting diode (LED) therapy is reported to be a potential therapeutic strategy for many diseases including neurodegenerative diseases. However, little is known about the anti-inflammatory effect of LED therapy on activated microglial cells, even less is known whether there is a synergistic anti-inflammatory effect exist in LED and luteolin therapy. In this study, we aimed to confirm the anti-inflammatory effect of luteolin and LED combination therapy in lipopolysaccharide (LPS)-stimulated BV2 microglial cells. We showed that luteolin inhibited LPS-induced cytotoxicity, tumor necrosis factor alpha (TNFα) and interleukin-6 (IL-6) production through modulation of p38 and extracellular signal-regulated kinase (ERK) signaling in BV2 cells. In addition, LED therapy enhanced the anti-inflammatory effect of luteolin. These results suggest that a synergistic effect between luteolin and LED could be a new effective therapy in relieving neuroinflammation.