Furanodien-6-one from Commiphora erythraea inhibits the NF-κB signalling and attenuates LPS-induced neuroinflammation

Microfluidic/HPLC combination to study carnosine protective activity on challenged human microglia: Focus on oxidative stress and energy metabolism

Carnosine (β-alanyl-L-histidine) is a naturally occurring endogenous peptide widely distributed in excitable tissues such as the brain. This dipeptide possesses well-demonstrated antioxidant, anti-inflammatory, and anti-aggregation properties, and it may be useful for treatment of pathologies characterized by oxidative stress and energy unbalance such as depression and Alzheimer's disease (AD). Microglia, the brain-resident macrophages, are involved in different physiological brain activities such synaptic plasticity and neurogenesis, but their dysregulation has been linked to the pathogenesis of numerous diseases. In AD brain, the activation of microglia towards a pro-oxidant and pro-inflammatory phenotype has found in an early phase of cognitive decline, reason why new pharmacological targets related to microglia activation are of great importance to develop innovative therapeutic strategies. In particular, microglia represent a common model of lipopolysaccharides (LPS)-induced activation to identify novel pharmacological targets for depression and AD and numerous studies have linked the impairment of energy metabolism, including ATP dyshomeostasis, to the onset of depressive episodes. In the present study, we first investigated the toxic potential of LPS + ATP in the absence or presence of carnosine. Our studies were carried out on human microglia (HMC3 cell line) in which LPS + ATP combination has shown the ability to promote cell death, oxidative stress, and inflammation. Additionally, to shed more light on the molecular mechanisms underlying the protective effect of carnosine, its ability to modulate reactive oxygen species production and the variation of parameters representative of cellular energy metabolism was evaluated by microchip electrophoresis coupled to laser-induced fluorescence and high performance liquid chromatography, respectively. In our experimental conditions, carnosine prevented LPS + ATP-induced cell death and oxidative stress, also completely restoring basal energy metabolism in human HMC3 microglia. Our results suggest a therapeutic potential of carnosine as a new pharmacological tool in the context of multifactorial disorders characterize by neuroinflammatory phenomena including depression and AD.

Cytotoxic sesquiterpenoid dimers from the resin of Commiphora myrrha Engl

Seven undescribed sesquiterpenoid dimers, commiphomyrones A - G, together with three known analogs, were isolated from the resin of Commiphora myrrha Engl.. The structures of the undescribed compounds were elucidated based on a comprehensive analysis of spectroscopic data (NMR, UV, IR, and MS), and the absolute configurations were defined by comparing the experimental and calculated ECD spectra as well as by performing X-ray crystallographic analysis. All the isolated dimeric sesquiterpenoids feature a 7-oxabicyclo [2.2.1] hept-2-ene moiety formed by the [4 + 2] cycloaddition of two sesquiterpenoids. Commiphomyrones C and G and commiphoratone D showed cytotoxic activity against the HGC-27 cell line with IC50 values of 22.76, 25.01, and 27.51 μM, respectively.

Salmonid alphavirus non-structural protein 2 is a key protein that activates the NF-κB signaling pathway to mediate inflammatory responses

Salmonid alphavirus (SAV) infection of Atlantic salmon (Salmo salar) and rainbow trout (Oncorhynchus mykiss) causes pancreas disease (PD) with typical inflammatory responses, such as necrosis of the exocrine pancreas, cardiomyopathy and skeletal myopathy. However, the pathogenic mechanism underlying SAV infection is still unclear. Inflammation may cause damage to the body, but it is a defense response against infection by pathogenic microorganisms, of which nuclear factor-kappa B (NF-κB) is the main regulator. This study revealed that SAV can activate NF-κB, of which the viral nonstructural protein Nsp2 is the major activating protein. SAV activates the NF-κB signaling pathway by simultaneously up-regulating TLR3, 7, 8 and then the expression of the signaling molecule myeloid differentiation factor 88 (Myd88) and tumor necrosis factor receptor-associated factor 6 (TRAF6). We found that Nsp2 can induce IκB degradation and p65 phosphorylation and transnucleation, and activate NF-κB downstream inflammatory cytokines. Nsp2 may simultaneously activate NF-κB through TLR3,7,8-dependent signaling pathways. Overexpression of Nsp2 can up-regulate mitochondrial antiviral signaling protein (MAVS) and then promote the expression of IFNa1 and antiviral protein Mx, which inhibits viral replication. This study shows that Nsp2 acts as a key activator protein for the NF-κB signaling pathway, which induces inflammation post-SAV infection. This study systematically analyzes the molecular mechanism of SAV activation of the NF-κB signaling pathway, and provides a theoretical basis for revealing the mechanism of innate immune response and inflammatory injury caused by SAV.

Phytochemical Composition of Commiphora Oleogum Resins and Their Cytotoxicity against Skin Cancer Cells

Oleogum resins of the genus Commiphora have been used in traditional medicines for centuries. More than 200 Commiphora species exhibit highly variable phytochemical compositions. A novel highly selective, sensitive, accurate HPLC-MS/MS method was developed and validated to quantify five characteristic phytosteroids and furanosesquiterpenoids, namely (E)-guggulsterone, (Z)-guggulsterone, curzerenone, furanoeudesma-1,3-diene, and myrrhone. The resulting contents and additionally GC analysis were used to classify and differentiate Commiphora oleogum resins of the species C. myrrha, C. erythraea, C. mukul, C. holtziana, C. confusa, and C. kua, as well as unspecified resins. Interestingly, a Commiphora sample from Ogaden, Ethiopia, comprised 446 ng/mg guggulsterones presumed to be unique to C. mukul from the Indian subcontinent. However, Commiphora from Ogaden differed considerably from C. mukul in respect to guggulsterones isomer’s ratio. Moreover, the cytotoxicity of Commiphora extracts, essential oils, botanical drugs containing Commiphora, and pure compounds against the epidermoid carcinoma A431, malignant melanoma RPMI-7951 and SK-MEL-28 cells was investigated in vitro. Thereby, especially C. mukul extract and C. myrrha essential oil exhibited high cytotoxicity against skin cancer cells with IC₅₀ of 2.9–10.9 µg/mL, but were less toxic to normal keratinocytes. In summary, Commiphora oleogum resins and its phytochemicals warrant further investigation aiming at chemotaxonomical classification as well as application in skin cancer treatment.

Serum Metabolomics Based on GC-MS Reveals the Antipyretic Mechanism of Ellagic Acid in a Rat Model

Ellagic acid (EA) is a polyphenol dilactone that has been reported to have antipyretic, anti-inflammatory, anti-tumor, and antioxidant activities, but the mechanism of action has not been reported. In this study, serum metabolomics was used to explore the mechanism of EA on rat fever induced by beer yeast, and to screen out marker metabolites to provide a reference for the antipyretic effect of EA. The acute fever model of male Sprague Dawley rats involved subcutaneous injection with 20% aqueous suspension of yeast (15 mL/kg) in their back. At the same time of modeling, EA was given orally by 10 mL/kg intragastric administration for treatment. During the experiment, the temperature and its change values of rats were recorded, and Interleukin-6 (IL-6), Tumor Necrosis Factor-α (TNF-α), Prostaglandin E2 (PGE2), Cyclic Adenosine Monophosphate (cAMP), Superoxide Dismutase (SOD) and Malondialdehyde (MDA)—six physiological and biochemical indexes of rats—were detected after the experiment. In addition, the hypothalamus of each rat was analyzed by Western blot (WB), and the levels of Phospho Nuclear Factor kappa-B (P-NF-κB P65) and IkappaB-alpha (IKB-α) were detected. Then, the serum metabolites of rats in each group were detected and analyzed by gas chromatograph mass spectrometry and the multivariate statistical analysis method. Finally, when screening for differential metabolites, the potential target metabolic pathway of drug intervention was screened for through the enrichment analysis of differential metabolites. Pearson correlation analysis was used to systematically characterize the relationship between biomarkers and pharmacodynamic indicators. EA could reduce the temperature and its change value in yeast induced fever rats after 18 h (p < 0.05). The level of IL-6, TNF-α, PGE2, cAMP, SOD and MDA of the Model group (MG) increased significantly compared to the Normal group (NG) (p < 0.001) after EA treatment, while the levels of the six indexes in the serum and cerebrospinal fluid of yeast-induced rats decreased. The administration of yeast led to a significant increase in Hypothalamus P-NF-κB P65 and IKB-α levels. Treatment with EA led to a significant decrease in P-NF-κB P65 levels. Moreover, combined with VIP > 1 and p < 0.05 as screening criteria, the corresponding retention time and characteristic mass to charge ratio were compared with the NIST library, Match score > 80%, and a total of 15 differential metabolites were screened. EA administration significantly regulated 9 of 15 metabolites in rat serum. The 15 differential metabolites involved linoleic acid metabolism, phenylalanine, tyrosine and tryptophan biosynthesis, galactose metabolism, biosynthesis of unsaturated fatty acids and glycerolipid metabolism. Pharmacodynamic correlation analysis was conducted between 15 different metabolites and six detection indexes. There was a significant correlation between 13 metabolites and six detection indexes. D-(−)-lactic acid, glycerin, phosphoric acid, 5-oxo-L-proline were negatively correlated with TNF-α, and p values were statistically significant except for L-tyrosine. In addition, glycerin was negatively correlated with IL-6, PGE2 and MDA, while phosphoric acid was negatively correlated with IL-6. In conclusion, EA may play an antipyretic anti-inflammatory role through the inhibition of the IKB-α/NF-κB signaling pathway and five metabolic pathways, which may contribute to a further understanding of the therapeutic mechanisms of the fever of EA.

LY294002 attenuates inflammatory response in endotoxin-induced uveitis by downregulating JAK3 and inactivating the PI3K/Akt signaling

CONTEXT

Uveitis is a prevalent inflammatory eye disease that damages the vision of patients and even leads to blindness. LY294002, an inhibitor of PI3K, was reported to suppress the inflammation and alleviate the progression of many diseases. However, the function of LY294002 in uveitis is unclear.

OBJECTIVE

This study aimed to explore the function of LY294002 in endotoxin-induced uveitis (EIU).

MATERIALS AND METHODS

EIU rat models were established via a single intravitreal injection of LPS. At 24 h after LPS injection, the rats received LY294002 treatment for 14 days. The histopathology was observed by H&E staining. The concentration of proinflammatory cytokines in aqueous humor was tested by ELISA. The expression of proinflammatory cytokines in the iris ciliary body (ICB) and retina of EIU rats were detected by RT-qPCR. JAK3, PI3K, and Akt expression were assessed by RT-qPCR and western blotting. Translocation of Akt in rat retinal Müller cells (rMC-1) was evaluated by immunofluorescence staining.

RESULTS

LY294002 alleviated ocular inflammation and decreased inflammatory cell infiltration in the anterior chamber, iris, ciliary body, vitreous cavity, and retina of EIU rats. LY294002 decreased the concentration of proinflammatory cytokines INF-γ, IL-17, IL-6, TNF-α, and IL-1β in aqueous humor and their expression in the ICB and retina of EIU rats. LY294002 downregulated JAK3 expression in EIU rats. LY294002 inhibited p-PI3K and p-Akt expression in EIU rats and restrained Akt translocation from cytoplasm to cell membrane in LPS-treated rMC-1 cells.

CONCLUSION

LY294002 ameliorates inflammation in EIU by downregulating JAK3 and inactivating the PI3K/Akt signaling.

Seeing the Unseen of the Combination of Two Natural Resins, Frankincense and Myrrh: Changes in Chemical Constituents and Pharmacological Activities

For the treatment of diseases, especially chronic diseases, traditional natural drugs have more effective therapeutic advantages because of their multi-target and multi-channel characteristics. Among many traditional natural medicines, resins frankincense and myrrh have been proven to be effective in the treatment of inflammation and cancer. In the West, frankincense and myrrh have been used as incense in religious and cultural ceremonies since ancient times; in traditional Chinese and Ayurvedic medicine, they are used mainly for the treatment of chronic diseases. The main chemical constituents of frankincense and myrrh are terpenoids and essential oils. Their common pharmacological effects are anti-inflammatory and anticancer. More interestingly, in traditional Chinese medicine, frankincense and myrrh have been combined as drug pairs in the same prescription for thousands of years, and their combination has a better therapeutic effect on diseases than a single drug. After the combination of frankincense and myrrh forms a blend, a series of changes take place in their chemical composition, such as the increase or decrease of the main active ingredients, the disappearance of native chemical components, and the emergence of new chemical components. At the same time, the pharmacological effects of the combination seem magically powerful, such as synergistic anti-inflammation, synergistic anticancer, synergistic analgesic, synergistic antibacterial, synergistic blood-activation, and so on. In this review, we summarize the latest research on the main chemical constituents and pharmacological activities of these two natural resins, along with chemical and pharmacological studies on the combination of the two.

Phytochemistry of Commiphora erythraea: A Review

Commiphora erythraea (Burseraceae) resin derives from the bark injury of the plant, a small tree native to the Arabian Peninsula. The resin is commonly known as myrrh and it is traditionally used to protect livestock from ticks and to treat diseases related to inflammation. The resin is constituted by a volatile and a non-volatile fraction. The volatile fraction is a source of furanosesquiterpenoids among which furanodienone showed to be the most promising pharmacological active compound. The composition and pharmacological activities of the extracts and the isolated compounds have been reviewed.

Pristimerin Inhibits LPS-Triggered Neurotoxicity in BV-2 Microglia Cells Through Modulating IRAK1/TRAF6/TAK1-Mediated NF-κB and AP-1 Signaling Pathways In Vitro

Microglia plays a prominent role in the brain's inflammatory response to injury or infection by migrating to affected locations and secreting inflammatory molecules. However, hyperactivated microglial is neurotoxic and plays critical roles in the pathogenesis of neurodegenerative diseases. Pristimerin, a naturally occurring triterpenoid, possesses antitumor, antioxidant, and anti-inflammatory activities. However, the effect and the molecular mechanism of pristimerin against lipopolysaccharide (LPS)-induced neurotoxicity in microglia remain to be revealed. In the present study, using BV-2 microglial cultures, we investigated whether pristimerin modifies neurotoxicity after LPS stimulation and which intracellular pathways are involved in the effect of pristimerin. Here we show that pristimerin markedly suppressed the release of Regulated on Activation, Normal T Expressed and Secreted (RANTES), transforming growth factor-β1 (TGF-β1), IL-6, tumor necrosis factor-α (TNF-α), and nitric oxide (NO). Pristimerin also significantly inhibited migration of BV-2 microglia and alleviated the death of neuron-like PC12 cell induced by the conditioned medium from LPS-activated BV-2 microglial cells. Moreover, pristimerin reduced the expression and interaction of TNF Receptor-Associated Factor 6 (TRAF6) and Interleukin-1 Receptor-Associated Kinases (IRAK1), limiting TGF-beta activating kinase 1 (TAK1) activation, and resulting in an inhibition of IKKα/β/NF-κB and MKK7/JNK/AP-1 signaling pathway in LPS-activated BV-2 microglia. Taken together, the anti-neurotoxicity action of pristimerin is mediated through the inhibition of TRAF6/IRAK1/TAK1 interaction as well as the related pathways: IKKα/β/NF-κB and MKK7/JNK/AP-1 signaling pathways. These findings may suggest that pristimerin might serve as a new therapeutic agent for treating hyperactivated microglial induced neurodegenerative diseases.

The ethyl acetate fraction from Physalis alkekengi inhibits LPS-induced pro-inflammatory mediators in BV2 cells and inflammatory pain in mice

ETHNOPHARMACOLOGICAL RELEVANCE

Physalis alkekengi is an edible herb whose fruit and calyx are traditionally used to treat a wide range of diseases including inflammation, toothache, and rheumatism. However, the effects of Physalis alkekengi fruit along with its calyx (PAF) on neuroinflammation and inflammatory pain behavior have not been reported yet.

AIM OF THE STUDY

This study evaluated the anti-inflammatory effect of PAF on lipopolysaccharide (LPS)-induced neuroinflammation and several in vivo model of inflammatory pain in mice.

MATERIALS AND METHODS

Here, first we studied the effects of PAF fractions on the production of pro-inflammatory mediators in LPS-treated BV2 microglial cells using enzyme-linked immunosorbent assay. The translocation of nuclear factor-kappa B (NF-κB) and the involvements of Akt and mitogen-activated protein (MAP) kinases in ethyl acetate fraction of PAF (PAF-EA)-mediated anti-inflammatory effect were measured using Western blotting. In in vivo experiments, the efficacy of PAF-EA was evaluated at the doses of 100 and 200mg/kg using several chemical-induced models of inflammatory pain such as acetic acid-induced writhing, formalin-induced paw licking and edema.

RESULTS

We found that compared to other fractions, the PAF-EA more potently inhibited the LPS-induced generation of nitric oxide, tumor necrosis factor-α, interleukin-6 and reactive oxygen species. It also inhibited LPS-induced nuclear translocation of NF-κB. These actions of EA fraction were found to be associated with a disruption of Akt and MAP kinases signaling pathways. The EA fraction also significantly inhibited acetic acid-induced writhing, formalin-induced licking time and edema in mice.

CONCLUSIONS

Our findings support the ethnopharmacological use of P. alkekengi fruit along with its calyx as an anti-inflammatory agent and suggest that the EA fraction of PAF may serve as a potential candidate to treat different neurological disorders and pain associated with inflammation.

IL-17A is implicated in lipopolysaccharide-induced neuroinflammation and cognitive impairment in aged rats via microglial activation

BACKGROUND

Neuroinflammation is considered a risk factor for impairments in neuronal function and cognition that arise with trauma, infection, and/or disease. IL-17A has been determined to be involved in neurodegenerative diseases such as multiple sclerosis. Recently, IL-17A has been shown to be upregulated in lipopolysaccharide(LPS)-induced systemic inflammation. This study aims to explore the role of IL-17A in LPS-induced neuroinflammation and cognitive impairment.

METHODS

Male Sprague-Dawley (SD) rats were injected intraperitoneally with LPS (500 μg/kg), and IL-17A expression in serum and in the hippocampus was examined 6, 12, 24, and 48 h later. Then, we investigated whether IL-17A-neutralizing antibodies (IL-17A Abs, 1 mg/kg) prevented neuroinflammation and memory dysfunction in aged rats that received LPS (500 μg/kg) injection. In addition, the effect of IL-17A on microglial activation in vitro was determined using ELISA and immunofluorescence.

RESULTS

LPS injection increased the expression of IL-17A in serum and in the hippocampus. IL-17A Abs improved LPS-induced memory impairment. In addition, IL-17A Abs prevented the LPS-induced expression of TNF-α, IL-6 and inflammatory proteins, and of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) as well as the activation of microglia in the brain. IL-17A Abs also inhibited the expression of amyloid precursor protein (APP) and BACE1 and increased the expression of the synaptic marker PSD95 in the aged rats treated with LPS. In an in vitro study, we found that recombinant IL-17A could simulate microglial activation and increase production of pro-inflammatory cytokines.

CONCLUSION

Taken together, our results suggest that IL-17A was involved in LPS-induced neuroinflammation and cognitive impairment in aged rats via microglial activation. Anti-IL-17A may represent a new therapeutic strategy for the treatment of endotoxemia-induced neuroinflammation and cognitive dysfunction.

Cyclic dipeptides: from bugs to brain

Cyclic dipeptides (CDPs) are a group of hormone-like molecules that are evolutionarily conserved from bacteria to humans. In bacteria, CDPs are used in quorum sensing (QS) to communicate information about population size and to regulate a behavioural switch from symbiosis with their host to virulence. In mammals, CDPs have been shown to act on glial cells (macrophage-like cells) to control a conceptually homologous behavioural switch between homeostatic and inflammatory modes, with implications for the control of neurodegenerative disease. Here we argue that, because of their capacity to regulate inflammation via glial cells and induce a protective response in neuronal cells, CDPs have potential therapeutic utility in an array of inflammatory diseases.