Anti-Inflammatory Effects of Aster incisus through the Inhibition of NF-κB, MAPK, and Akt Pathways in LPS-Stimulated RAW 264.7 Macrophages

Ali S, Efferth T, Hegazy MEF. Salvimulticanol from Salvia multicaulis suppresses LPS-induced inflammation in RAW264.7 macrophages: in vitro and in silico studies

Sustained inflammatory responses can badly affect several vital organs and lead to chronic inflammation-related disorders, such as atherosclerosis, pneumonia, rheumatoid arthritis, obesity, diabetes, Alzheimer's disease, and cancers. Salvia multicaulis is one of the widely distributed plants that contains several biologically active phytochemicals and diterpenoids with anti-inflammatory effects. Therefore, finding alternative and safer natural plant-extracted compounds with good curative anti-inflammatory efficiencies is an urgent need for the clinical treatment of inflammation-related diseases. In the current study, S. multicaulis Vahl was used to extract and isolate two compounds identified as salvimulticanol and candesalvone B methyl ester to examine their effects against inflammation in murine macrophage RAW264.7 cells that were induced by lipopolysaccharide (LPS). Accordingly, after culturing RAW264.7 cells and induction of inflammation by LPS (100 ng/ml), cells were exposed to different concentrations (9, 18, 37.5, 75, and 150 µM) of each compound. Then, Griess assay for detection of nitric oxide (NO) levels and western blotting for the determination of inducible nitric oxide synthase (iNOS) expression were performed. Molecular docking and molecular dynamics (MD) simulation studies were employed to investigate the anti-inflammatory mechanism. Our obtained results validated that the level of NO was significantly decreased in the macrophage cell suspensions as a response to salvimulticanol treatment in a dose-dependent manner (IC50: 25.1 ± 1.2 µM) as compared to the methyl ester of candesalvone B which exerted a weaker inhibition (IC50: 69.2 ± 3.0 µM). This decline in NO percentage was comparable with a down-regulation of iNOS expression by western blotting. Salvimulticanol strongly interacted with both the Toll-like receptor 4 (TLR4)/myeloid differentiation factor 2 (MD-2) complex and the inhibitor of nuclear factor kappa-B (NF-κB) kinase subunit beta (IKKβ) to disrupt their inflammatory activation due to the significant hydrogen bonds and effective interactions with amino acid residues present in the target proteins' active sites. S.multicaulis is a rich natural source of the aromatic abietane diterpenoid, salvimulticanol, which exerted a strong anti-inflammatory effect through targeting iNOS and diminishing NO production in LPS-induced RAW264.7 cells in a mechanism that is dependent on the inhibition of TLR4-MD-2 and IKKβ as activators of the classical NF-κB-mediated inflammatory pathway.

Anti-Inflammatory Chilean Endemic Plants

Medicinal plants have been used since prehistoric times and continue to treat several diseases as a fundamental part of the healing process. Inflammation is a condition characterized by redness, pain, and swelling. This process is a hard response by living tissue to any injury. Furthermore, inflammation is produced by various diseases such as rheumatic and immune-mediated conditions, cancer, cardiovascular diseases, obesity, and diabetes. Hence, anti-inflammatory-based treatments could emerge as a novel and exciting approach to treating these diseases. Medicinal plants and their secondary metabolites are known for their anti-inflammatory properties, and this review introduces various native Chilean plants whose anti-inflammatory effects have been evaluated in experimental studies. Fragaria chiloensis, Ugni molinae, Buddleja globosa, Aristotelia chilensis, Berberis microphylla, and Quillaja saponaria are some native species analyzed in this review. Since inflammation treatment is not a one-dimensional solution, this review seeks a multidimensional therapeutic approach to inflammation with plant extracts based on scientific and ancestral knowledge.

Silymarin-Functionalized Selenium Nanoparticles Prevent LPS-Induced Inflammatory Response in RAW264.7 Cells through Downregulation of the PI3K/Akt/NF-κB Pathway

Silymarin exhibits an anti-inflammatory property in various cancers and inflammatory diseases. In our previous work, silymarin-mediated selenium nanoparticles (SeNPs) (Si-SeNPs) were developed using a green synthesis technique, and its potential as an anticancer agent was confirmed. In order to further examine the extended comprehensive potential of Si-SeNPs, this investigation focuses on studying the enhanced anti-inflammatory effect of Si-SeNPs in lipopolysaccharide (LPS)-stimulated RAW264.7 macrophages. Enzyme-linked immunosorbent assay and quantitative reverse transcription-polymerase chain reaction were used to evaluate the expression of pro-inflammatory mediators and cytokines. Western blotting and immunofluorescence assays were conducted to assess the protein expression of p-PI3K, p-Akt, p-NF-κB, and p-IκBα. Compared to silymarin, Si-SeNPs exhibited a significantly increased inhibitory effect on LPS-induced release of nitric oxide and the expression of pro-inflammatory cytokines such as tumor necrosis factor-alpha (TNF-α) and interleukin 1β (IL-1β) in RAW264.7 cells. A western blot assay indicated that Si-SeNPs downregulated the PI3K/Akt and NF-κB signaling pathways. The immunofluorescence assay suggested that Si-SeNPs inhibited the nuclear translocation and the activation of NF-κB. In addition, 740 Y-P (PI3K agonist) was used to demonstrate that activating the PI3K/Akt signal could partially reverse the inflammatory response, suggesting a causal role of the PI3K/Akt signaling pathway in the anti-inflammatory effect of Si-SeNPs. Consequently, these findings indicate that Si-SeNPs could be a functional agent of the attenuation of LPS-induced inflammatory responses in RAW264.7 macrophages through inhibiting the PI3K/Akt/NF-κB signaling pathway. In addition, biosynthesized Si-SeNPs could be more effective at reducing inflammation than only silymarin extracts. Thus, this study lays an experimental foundation for the clinical application of using biosynthesized SeNPs as a novel candidate in the field of inflammation-associated diseases.

Anti‑inflammatory effects of Nypa fruticans Wurmb via NF‑κB and MAPK signaling pathways in macrophages

The inflammatory defense response of macrophages is a natural protective reaction in the immune system. Antioxidant and anti-inflammatory activities are closely related. In addition, the cell signaling pathway regulating inflammation is associated with MAPK and NF-κB signaling pathway phosphorylation. The present study aimed to evaluate whether the ethyl acetate fraction from N. fruticans (ENF) has a modulatory role in the MAPK signaling pathway and inhibition of the IκB/NF-κB signaling pathways, including translocation of NF-κB p65. Antioxidant and anti-inflammatory activities are closely related. In addition, the cell signaling pathway regulating inflammation is associated with MAPK and NF-κB signaling pathway phosphorylation. The results revealed that ENF exhibited antioxidant capacity, attenuated the cytokine levels and blocked nitric oxide production. ENF downregulated cyclooxygenase-2 and inducible nitric oxide synthase expression. We hypothesized that ENF treatment alleviated the various proinflammatory mediators via IκB phosphorylation and transcription of NF-κB compared with the untreated control. In conclusion, the present study demonstrated that the inhibitory effect of ENF treatment was attributed to the inhibition of MAPK and Akt/IκB/NF-κB signaling pathways.

Amelioration of TPA-induced skin inflammation by the leaf extract of Vernonia amygdalina involves ERK/STAT3 (Ser727) signaling inhibition

BACKGROUND

Uncontrolled inflammation causes health problems. Extracellular signal-regulated kinase (ERK) phosphorylates signal transducer and activator of transcription 3 (STAT3) at Ser727, resulting in inflammation. The leaf of Vernonia amygdalina (VA) is a medicinal herb for managing inflammation-associated diseases. Oral administration or topical application of VA leaf extract exerts anti-inflammatory effects in rat models. However, the anti-inflammatory mechanisms of the herb are not fully understood.

PURPOSE

In this study, we aimed to investigate the involvement of ERK/STAT3 (Ser727) signaling in the anti-inflammatory effects of an ethanolic extract of VA leaves.

STUDY DESIGN AND METHODS

Extracts of VA leaves were prepared with different concentrations of ethanol. A LPS-stimulated RAW264.7 cell model was used for in vitro assays, and a TPA (12-O-tetradecanoylphorbol-13-acetate)-induced ear edema mouse model was employed for in vivo assays. The 95% ethanol extract of VA leaves (VAE) exerted the strongest inhibitory effect on nitric oxide (NO) production in LPS-stimulated macrophages; thus it was selected for use in this study. Hematoxylin and eosin (H&E) staining was used to examine pathological conditions of mouse ear tissues. Griess reagent was employed to examine NO generation in cell cultures. Immunoblotting and ELISA were used to examine protein levels, and RT-qPCR was employed to examine mRNA levels.

RESULTS

Topical application of VAE ameliorated mouse ear edema induced by TPA. VAE suppressed the phosphorylation of ERK (Thr202/Tyr204) and STAT3 (Ser727); and decreased protein levels of inducible nitric oxide synthase (iNOS), cyclooxygenase-2 (COX-2), interleukin (IL)-6, IL-1β and tumor necrosis factor-α (TNF-α) in the mouse ear tissues and in LPS-stimulated RAW 264.7 cells. VAE also inhibited NO production, and lowered mRNA levels of IL-6, IL-1β and TNF-α in the macrophages.

CONCLUSIONS

VAE ameliorates TPA-induced mouse ear edema. Suppression of ERK/STAT3 (Ser727) signaling is involved in VAE's anti-inflammatory effects. These novel data provide further pharmacological justifications for the medicinal use of VA in treating inflammation-associated diseases, and lay the groundwork for developing VAE into a new anti-inflammatory agent.

Are TRPA1 and TRPV1 channel-mediated signalling cascades involved in UVB radiation-induced sunburn?

Burn injuries are underappreciated injuries associated with substantial morbidity and mortality. Overexposure to ultraviolet (UV) radiation has dramatic clinical effects in humans and is a significant public health concern. Although the mechanisms underlying UVB exposure are not fully understood, many studies have made substantial progress in the pathophysiology of sunburn in terms of its molecular aspects in the last few years. It is well established that the transient receptor potential ankyrin 1 (TRPA1), and vanilloid 1 (TRPV1) channels modulate the inflammatory, oxidative, and proliferative processes underlying UVB radiation exposure. However, it is still unknown which mechanisms underlying TRPV1/A1 channel activation are elicited in sunburn induced by UVB radiation. Therefore, in this review, we give an overview of the TRPV1/A1 channel-mediated signalling cascades that may be involved in the pathophysiology of sunburn induced by UVB radiation. These data will undoubtedly help to explain the various features of sunburn and contribute to the development of novel therapeutic approaches to better treat it.

Anti-Inflammatory Activity of Extracts and Pure Compounds Derived from Plants via Modulation of Signaling Pathways, Especially PI3K/AKT in Macrophages

The plant kingdom is a source of important therapeutic agents. Therefore, in this review, we focus on natural compounds that exhibit efficient anti-inflammatory activity via modulation signaling transduction pathways in macrophage cells. Both extracts and pure chemicals from different species and parts of plants such as leaves, roots, flowers, barks, rhizomes, and seeds rich in secondary metabolites from various groups such as terpenes or polyphenols were included. Selected extracts and phytochemicals control macrophages biology via modulation signaling molecules including NF-κB, MAPKs, AP-1, STAT1, STAT6, IRF-4, IRF-5, PPARγ, KLF4 and especially PI3K/AKT. Macrophages are important immune effector cells that take part in antigen presentation, phagocytosis, and immunomodulation. The M1 and M2 phenotypes are related to the production of pro- and anti-inflammatory agents, respectively. The successful resolution of inflammation mediated by M2, or failed resolution mediated by M1, may lead to tissue repair or chronic inflammation. Chronic inflammation is strictly related to several disorders. Thus, compounds of plant origin targeting inflammatory response may constitute promising therapeutic strategies.

The immunoenhancement effects of starfish Asterias rollestoni polysaccharides in macrophages and cyclophosphamide-induced immunosuppression mouse models

The water-soluble polysaccharide, SF-2, obtained from starfish (Asterias rollestoni), belongs to the group of polysaccharides known as mannoglucan sulfate. It is composed of mannose as well as glucose and contains 13.85% SO₄^2-. We aimed to detect the immunoenhancement effects of SF-2 in macrophages and cyclophosphamide (CYP)-induced immunosuppression mouse models. RAW 264.7 macrophage cells were treated with SF-2 for different periods of time (0 h, 0.5 h, 1 h, 3 h, 6 h, and 9 h) and the results showed that SF-2 promoted the production of nitric oxide and up-regulated the levels of pro-inflammatory cytokines and related proteins, such as TNF-α, IL-1β, IL-6, COX-2, MMP-9, and iNOS in a time-dependent manner. In addition, SF-2 activated NLRP3 inflammasome and the MAPK/NF-κB signaling pathway, thus promoting its immunoenhancement effects. Moreover, we co-cultured the primary peritoneal macrophages with SF-2 for 6 h and found that SF-2 enhanced the expression of NLRP3 inflammasome and the release of cytokines. Furthermore, SF-2 significantly increased the body weight, spleen index, thymus index, and inflammatory cell counts in CYP-induced immunosuppression mouse models. These results indicate that SF-2 is a potential immunoenhancement mediator that acts by activating the NLRP3 inflammasome and MAPK/NF-κB pathway.

Cudraflavanone B Isolated from the Root Bark of Cudrania tricuspidata Alleviates Lipopolysaccharide-Induced Inflammatory Responses by Downregulating NF-κB and ERK MAPK Signaling Pathways in RAW264.7 Macrophages and BV2 Microglia

A prenylated flavonoid, cudraflavanone B, is isolated from Cudrania tricuspidata. In this study, we investigated its anti-inflammatory and anti-neuroinflammatory effects in lipopolysaccharide (LPS)-induced RAW264.7 and BV2 cells. In our initial study of the anti-inflammatory effects of cudraflavanone B the production of nitric oxide and prostaglandin E2 was attenuated in LPS-stimulated RAW264.7 and BV2 cells. These inhibitory effects were related to the downregulation of inducible nitric oxide synthase and cyclooxygenase-2. In addition, cudraflavanone B suppressed the production of pro-inflammatory cytokines such as interleukin-6 and tumor necrosis factor-α in LPS-induced RAW264.7 and BV2 cells. Moreover, the evaluation of the molecular mechanisms underlying the anti-inflammatory effects of cudraflavanone B revealed that the compound attenuated the nuclear factor-kappa B signaling pathway in LPS-induced RAW264.7 and BV2 cells. In addition, cudraflavanone B inhibited the phosphorylation of extracellular signal-regulated kinase mitogen-activated protein kinase signaling pathways in these LPS-stimulated cells. Thus, cudraflavanone B suppressed nuclear factor-κB, and extracellular signal-regulated kinase mitogen-activated protein kinase mediated inflammatory pathways, demonstrating its potential in the treatment of neuroinflammatory conditions.

Immunomodulatory Effects of a Low-Molecular Weight Polysaccharide from Enteromorpha prolifera on RAW 264.7 Macrophages and Cyclophosphamide- Induced Immunosuppression Mouse Models

The water-soluble polysaccharide EP2, from Enteromorpha prolifera, belongs to the group of polysaccharides known as glucuronoxylorhamnan, which mainly contains glucuronic acid (GlcA), xylose (Xyl), and rhamnose (Rha). The aim of this study was to detect the immunomodulatory effects of EP2 on RAW 264.7 macrophages and cyclophosphamide (CYP)-induced immunosuppression mouse models. The cells were treated with EP2 for different time periods (0, 0.5, 1, 3, and 6 h). The results showed that EP2 promoted nitric oxide production and up-regulated the expression of pro-inflammatory cytokines, such as IL-1β, IL-6, and TNF-α, in a time-dependent manner. Furthermore, we found that EP2-activated iNOS, COX2, and NLRP3 inflammasomes, and the TLR4/MAPK/NF-κB signaling pathway played an important role. Moreover, EP2 significantly increased the body weight, spleen index, thymus index, inflammatory cell counts, and the levels of IL-1β, IL-6, and TNF-α in CYP-induced immunosuppression mouse models. These results indicate that EP2 might be a potential immunomodulatory drug and provide the scientific basis for the comprehensive utilization and evaluation of E. prolifera in future applications.

Anti-inflammatory properties of the marine plant Posidonia oceanica (L.) Delile

ETHNOPHARMACOLOGICAL RELEVANCE

Posidonia oceanica (L.) Delile is an endemic seagrass of the Mediterranean Sea whose use has been documented as a traditional herbal remedy for diabetes and hypertension. Our recently described Posidonia oceanica leaves extract is a phytocomplex endowed with interesting bioactivities, including the inibitory property on human cancer cell migration.

AIM OF THE STUDY

The aim of this study was to investigate the anti-inflammatory effects of P. oceanica extract underlying its mechanism of action.

MATERIALS AND METHODS

We explored the anti-inflammatory effects of P. oceanica extract on RAW264.7 murine macrophages activated by LPS. We investigated the reactive oxygen species (ROS) and nitric oxide (NO) production and the expression of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2). Then, we examined P. oceanica extract role on the regulation of NF-κB signaling pathway.

RESULTS

P. oceanica phytocomplex exhibited a strong ability to inhibit oxidative stress by affecting the production of both ROS and NO and to reduce iNOS and COX-2 levels. In addition, it was evidenced its anti-inflammatory role via inhibiting NF-κB signaling pathway through modulation of ERK1/2 and Akt intracellular cascades.

CONCLUSIONS

Our results recognize an anti-inflammatory role of P. oceanica phytocomplex particularly emphasizing its cell safe mechanism of action. In conclusion, the marine plant P. oceanica may be of great interest for scientific research as a source of promising molecules for designing alternative strategies to the conventional treatment of inflammatory diseases.

Anti-inflammatory effects of doxepin hydrochloride against LPS-induced C6-glioma cell inflammatory reaction by PI3K-mediated Akt signaling

Recent studies have shown that tricyclic antidepressants (TCAs) may have anti-inflammatory and anticonvulsant effects in addition to its antidepressant effects. So far, the nonantidepressant effects of TCAs and their molecular pharmacological mechanisms remain completely unclear. Chronic inflammation in the brain parenchyma may be related to the pathogenesis and progression of various neurodegenerative diseases. As a common antidepressant and anti-insomnia drug, doxepin also may be a potential anti-inflammatory and anticonvulsant drug, so the study on the anti-inflammatory protective effect of doxepin and its molecular mechanism has become a very important issue in pharmacology and clinical medicine. Further elucidating the anti-inflammatory and neuroprotective effects of doxepin and its molecular mechanism may provide the important theoretical and clinical basis for the prevention and treatment of neurodegenerative disease. This study was designed to understand the glio-protective mechanism of doxepin against the inflammatory damage induced by lipopolysaccharide (LPS) exposure in C6-glioma cells. We found the treatment of C6-glioma cells with LPS results in deleterious effects, including the augmentation of inflammatory cytokine levels (tumor necrosis factor-α, interleukin-1β), and suppresses the Akt phosphorylation. Furthermore, our outcomes demonstrated that doxepin was able to suppress these effects induced by LPS, through activation of the phosphatidylinositol-3-kinase-mediated protein kinase B (Akt) pathway. To sum up, these results highlight the potential role of doxepin against neuroinflammatory-related disease in the brain.

miR-488 mediates negative regulation of the AKT/NF-κB pathway by targeting Rac1 in LPS-induced inflammation

Endometritis is an inflammatory change in the structure of the endometrium due to various causes and is a common cause of infertility. Studies have confirmed that microRNAs (miRNAs) play a key regulatory role in various inflammatory diseases. However, the miRNA-mediated mechanism of endometrial inflammation induced by lipopolysaccharides (LPS) remains unclear. In this study, real-time quantitative polymerase chain reaction, Western blot analysis, immunofluorescence and Rac family small GTPase 1 (Rac1) interference were used to reveal the overexpression of miR-488 in the LPS-induced bovine uterus, and the effect of protein kinase B κ-light chain enhancement of the nuclear factor-activated B cells (AKT/NF-κB) pathway in intimal epithelial cells. The results showed that the expression of inflammatory cytokines such as interleukin-1β (IL-1β), IL-6, and tumor necrosis factor-α in the experimental group was significantly lower than that in the control group when miR-488 was overexpressed. Similar results were observed in the expression levels of p-AKT, p-IKK, and p-p65 proteins. In addition, the dual-luciferase reporter system confirmed that miRNA-488 may directly target the 3'-untranslated region of Rac1. In turn, the expression of Rac1 was inhibited. Moreover, the nuclear translocation of NF-κB was inhibited, and meanwhile, the accumulation of reactive oxygen species (ROS) in the cells was reduced. Thus, we provide basic data for the negative regulation of miR-488 in LPS-induced inflammation by inhibiting ROS production and the AKT/NF-kB pathway in intimal epithelial cells.