Anti-inflammatory Effects of Vitamin E on Adjuvant-Induced Arthritis in Rats

Several lines of antioxidant defense against oxidative stress: antioxidant enzymes, nanomaterials with multiple enzyme-mimicking activities, and low-molecular-weight antioxidants

Reactive oxygen species (ROS) and reactive nitrogen species (RNS) are well recognized for playing a dual role, since they can be either deleterious or beneficial to biological systems. An imbalance between ROS production and elimination is termed oxidative stress, a critical factor and common denominator of many chronic diseases such as cancer, cardiovascular diseases, metabolic diseases, neurological disorders (Alzheimer's and Parkinson's diseases), and other disorders. To counteract the harmful effects of ROS, organisms have evolved a complex, three-line antioxidant defense system. The first-line defense mechanism is the most efficient and involves antioxidant enzymes such as superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx). This line of defense plays an irreplaceable role in the dismutation of superoxide radicals (O2•-) and hydrogen peroxide (H2O2). The removal of superoxide radicals by SOD prevents the formation of the much more damaging peroxynitrite ONOO- (O2•-  + NO• → ONOO-) and maintains the physiologically relevant level of nitric oxide (NO•), an important molecule in neurotransmission, inflammation, and vasodilation. The second-line antioxidant defense pathway involves exogenous diet-derived small-molecule antioxidants. The third-line antioxidant defense is ensured by the repair or removal of oxidized proteins and other biomolecules by a variety of enzyme systems. This review briefly discusses the endogenous (mitochondria, NADPH, xanthine oxidase (XO), Fenton reaction) and exogenous (e.g., smoking, radiation, drugs, pollution) sources of ROS (superoxide radical, hydrogen peroxide, hydroxyl radical, peroxyl radical, hypochlorous acid, peroxynitrite). Attention has been given to the first-line antioxidant defense system provided by SOD, CAT, and GPx. The chemical and molecular mechanisms of antioxidant enzymes, enzyme-related diseases (cancer, cardiovascular, lung, metabolic, and neurological diseases), and the role of enzymes (e.g., GPx4) in cellular processes such as ferroptosis are discussed. Potential therapeutic applications of enzyme mimics and recent progress in metal-based (copper, iron, cobalt, molybdenum, cerium) and nonmetal (carbon)-based nanomaterials with enzyme-like activities (nanozymes) are also discussed. Moreover, attention has been given to the mechanisms of action of low-molecular-weight antioxidants (vitamin C (ascorbate), vitamin E (alpha-tocopherol), carotenoids (e.g., β-carotene, lycopene, lutein), flavonoids (e.g., quercetin, anthocyanins, epicatechin), and glutathione (GSH)), the activation of transcription factors such as Nrf2, and the protection against chronic diseases. Given that there is a discrepancy between preclinical and clinical studies, approaches that may result in greater pharmacological and clinical success of low-molecular-weight antioxidant therapies are also subject to discussion.

Amelioration of Rheumatoid Arthritis by Fragaria nubicola (Wild Strawberry) via Attenuation of Inflammatory Mediators in Sprague Dawley Rats

Background and Objectives: Fragaria nubicola has never been evaluated scientifically for its anti-arthritic potential despite its use in folkloric systems of medicine. The research was conducted to assess the potential of F. nubicola against rheumatoid arthritis. Materials and Methods: The current study provided scientific evidence by evaluating the effects of plants using an in vivo CFA-induced model of arthritic rats and subsequent microscopic histopathological evaluation of ankle joints along with the determination of paw edema using a digital water displacement plethysmometer. The study also gave insight by determining levels of pro-inflammatory cytokines, matrix metalloproteinase enzymes (MMPs), prostaglandin E2 (PGE2), nuclear factor kappa B (NF-κB), vascular endothelial growth factor (VEGF), and biochemical and hematological parameters. GCMS analysis was also conducted for the identification of possible anti-inflammatory plant constituents. Results: The data showed that F. nubicola-treated groups attenuated the progression of arthritis and paw edema. Microscopic histopathological evaluation validated the anti-arthritic potential by showing amelioration of bone erosion, infiltration of inflammatory cells, and pannus formation. RT-PCR analysis displayed that treatment with F. nubicola down-regulated IL1β, IL6, TNFα, NF-κB, VEGF, MMP2, MMP3, and MMP9 levels. Moreover, ELISA exhibited a reduction in levels of PGE2 levels in treatment groups. The levels of RBCs, platelets, WBCs, and Hb content were found to be nearly similar to negative control in the treated group. Statistically, a non-significant difference was found when all groups were compared for urea, creatinine, ALT, and AST analysis, indicating the safety of plant extract and fractions at test doses. GCMS analysis of extract and fractions showed the existence of many anti-inflammatory and antioxidant phytochemicals. Conclusion: In conclusion, F. nubicola possessed anti-arthritic properties that might be attributed to the amelioration of MMPs and pro-inflammatory cytokines.

Sarcococca saligna extract attenuates formaldehyde-induced arthritis in Wistar rats via modulation of pro-inflammatory and inflammatory biomarkers

Sarcococca saligna plant is commonly used as traditional therapy for arthritis especially in Asian countries. The current study is designed to explore the anti-arthritic potential of S. saligna aqueous methanolic extract (SSME). Preliminary proximate study and HPLC analysis were performed to investigate the phytochemical characterization and quality control. The safety of the SSME was evaluated by performing an acute oral toxicity study (OECD guidelines 425). The anti-arthritic potential of SSME was explored by in vivo formaldehyde-induced arthritis model. The antiarthritic effect of the SSME was determined through paw diameter, arthritic index, body weight, biochemical and haematological parameters. Radiographic and histopathological studies were also carried out to evaluate the results. qRT-PCR was performed to determine the upregulation and downregulation of anti- and pro-inflammatory cytokines in rats while ELISA was done to determine the concentration of HSP-70, IL-6 and TNF-α in the serum. Results of acute oral toxicity showed no abnormality and mortality. There was no noticeable change in haematological and biochemical parameters. Histopathological examination exhibited the normal structure of vital organs. So, SSME might be safe at a 2000 mg/kg dose, proposing that LD₅₀ was higher than 2000 mg/kg body weight. Gallic acid, catechin, hydroxyl benzoic acid, sinapic acid, caffeic acid, ferulic acid and p-cumaric acid were identified by HPLC. The outcomes of in vivo formaldehyde-induced arthritic model showed that SSME significantly reduced paw inflammation and arthritic index and improved haematological and biochemical parameters. Moreover, the SSME influentially down-regulated the gene expression of IL-1β, IL-6, COX-2, PGE2, TNF-α and NF-κB, and up-regulated the expression of IL-4, and IL-10. The results of the undertaken study suggest that S. saligna have strong anti-arthritic activity supporting its conventional application as the remedy of rheumatoid arthritis.

Alpha-tocopherol-loaded polycaprolactone nanoparticles improve the inflammation and systemic oxidative stress of arthritic rats

Background and aim

The present study investigated the effects of orally administered α-tocopherol-loaded polycaprolactone nanoparticles on the articular inflammation and systemic oxidative status of middle-aged Holtzman rats with Freund's adjuvant-induced polyarthritis, a model for rheumatoid arthritis. Intraperitoneally administered free α-tocopherol provided the reference for comparison.

Experimental procedure

Two protocols of treatment were followed: intraperitoneal administration of free α-tocopherol (100 mg/kg i.p.) or oral administration of free and nanoencapsulated α-tocopherol (100 mg/kg p.o.). Animals were treated during 18 days after arthritis induction.

Results

Free (i.p.) and encapsulated α-tocopherol decreased the hind paws edema, the leukocytes infiltration into femorotibial joints and the mRNA expression of pro-inflammatory cytokines in the tibial anterior muscle of arthritic rats, but the encapsulated compound was more effective. Free (i.p.) and encapsulated α-tocopherol decreased the high levels of reactive oxygen species in the brain and liver, but only the encapsulated compound decreased the levels of protein carbonyl groups in these organs. Both free (i.p.) and encapsulated α-tocopherol increased the α-tocopherol levels and the ratio of reduced to oxidized glutathione in these organs.

Conclusion

Both intraperitoneally administered free α-tocopherol and orally administered encapsulated α-tocopherol effectively improved inflammation and systemic oxidative stress in middle-aged arthritic rats. However, the encapsulated form should be preferred because the oral administration route does not be linked to the evident discomfort that is caused in general by injectable medicaments. Consequently, α-tocopherol-loaded polycaprolactone nanoparticles may be a promising adjuvant to the most current approaches aiming at rheumatoid arthritis therapy.

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Oxidative stress is systemically increased in rats with adjuvant-induced arthritis.

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Arthritic rats were orally treated with α-tocopherol-loaded polycaprolactone nanoparticles.

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Treatment decreased the paw edema and articular inflammation of arthritic rats.

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Treatment improved the oxidative stress in the liver and brain arthritic rats.

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The content of α-tocopherol was increased in the brain and liver of treated rats.

METTL3 Promotes Activation and Inflammation of FLSs Through the NF-κB Signaling Pathway in Rheumatoid Arthritis

Rheumatoid arthritis (RA), a common autoimmune disease, is extremely damaging to human health. Fibroblast-like synoviocytes (FLSs) have a vital role in the occurrence and development of RA. Methyltransferase-like 3 (METTL3), which is a crucial component of the N⁶-methyladenosine (m⁶A) methyltransferase complex, is involved in the progression of many diseases. In this study, we explored the role of METTL3 in the inflammatory response and proliferation, invasion, and migration of FLSs. We used human RA synovial tissues and the adjuvant-induced arthritis (AIA) animal model of RA. Experimental results revealed that METTL3 expression was significantly upregulated in human RA synovial tissues and in the rat AIA model. METTL3 knockdown suppressed interleukin (IL)-6, matrix metalloproteinase (MMP)-3, and MMP-9 levels in human RA-FLSs and rat AIA-FLSs. In contrast, they were increased by METTL3 overexpression. Additionally, we found that, in FLSs, METTL3 may activate the nuclear factor (NF)-κB signaling pathway. The experimental results showed that METTL3 may promote FLS activation and inflammatory response via the NF-κB signaling pathway.

Vitamin E: A Review of Its Application and Methods of Detection When Combined with Implant Biomaterials

Vitamin E is a common compound used for tocopherols and tocotrienols (α, β, γ, δ); it is the component of many natural products of both plant and animal origin. Thanks to its powerful antioxidant capacity, vitamin E has been very successful in hip and knee arthroplasty, used to confer resistance to oxidation to irradiated UHMWPE. The positive results of these studies have made vitamin E an important object of research in the biomedical field, highlighting other important properties, such as anti-bacterial, -inflammatory, and -cancer activities. In fact, there is an extensive literature dealing with vitamin E in different kinds of material processing, drug delivery, and development of surface coatings. Vitamin E is widely discussed in the literature, and it is possible to find many reviews that discuss the biological role of vitamin E and its applications in food packaging and cosmetics. However, to date, there is not a review that discusses the biomedical applications of vitamin E and that points to the methods used to detect it within a solid. This review specifically aims to compile research about new biomedical applications of vitamin E carried out in the last 20 years, with the intention of providing an overview of the methodologies used to combine it with implantable biomaterials, as well as to detect and characterize it within these materials.

Alpha2-Adrenoblockers Regulate Development of Oxidative Stress and Cognitive Behaviour of Rats under Chronic Acoustic Stress Conditions

Noise is a wide-spread stress factor in modern life produced by urbanization, traffic, and an industrialized environment. Noise stress causes dysfunction and neurotransmission impairment in the central nervous system, as well as changes in hormone levels. In this study, we have examined the level of α-Tocopherol (α-T) and malondialdehyde (MDA) in plasma and the erythrocytes’ membrane (EM), as well as the behavioral characteristics of a noise-induced stress model in rats. In addition, the modulating effect of α²-adrenoblockers, beditin, and mesedin on the aforementioned parameters has been investigated. For these purposes, albino male rats were divided into four groups: (1) untreated; (2) noise-exposed, (3) noise-exposed and beditin-treated (2 mg/kg, i.p.), and (4) noise-exposed and mesedin-treated (10 mg/kg, i.p.) animals. Noise-exposed groups were treated with 91dBA noise on 60 days with a daily duration of 8 h. Increased MDA and decreased α-T levels in plasma and EM were observed upon chronic high-level noise exposure. Locomotor and behavioral activity assessed with a Y-maze revealed disorientation and increased anxiety under chronic noise exposure. Prominently, α²-adrenoblockers alleviated both behavioral deficits and oxidative stress, providing evidence for the involvement of α²-adrenoceptor in the pathophysiology of noise-induced stress.

Neuronal and non-neuronal transient receptor potential ankyrin 1 mediates UVB radiation-induced skin inflammation in mice

AIMS

Neuronal and non-neuronal TRPA1 channel plays an active role in the pathogenesis of several skin inflammatory diseases. Although a recent study identified the TRPA1 channel activation upon UVB exposure, its role in inflammatory, oxidative, and proliferative processes underlying UVB radiation-induced sunburn was not yet fully understood. We evaluated the TRPA1 channel contribution in inflammatory, oxidative, and proliferative states on skin inflammation induced by UVB radiation in mice.

MAIN METHODS

TRPA1 role was evaluated from inflammatory (ear edema, myeloperoxidase, and N-acetyl-β-D-glycosaminidase activities, histological changes, and cytokines levels), proliferative (epidermal hyperplasia, PCNA, and TRPA1 levels), and oxidative (reactive oxygen intermediates measure, H₂O₂ quantification, and NADPH oxidase activity) parameters caused by UVB radiation single (0.5 J/cm²) or repeated (0.1 J/cm²) exposure. We verified the contribution of non-neuronal and neuronal TRPA1 on UVB radiation-induced inflammatory parameters using RTX-denervation (50 μg/kg s.c.).

KEY FINDINGS

TRPA1 blockade by the selective antagonist Lanette® N HC-030031 reduced all parameters induced by UVB radiation single (at concentration of 1%) or repeated (at concentration of 0.1%) exposure. We evidenced an up-regulation of the TRPA1 protein after UVB radiation repeated exposure, which was blocked by topical Lanette® N HC-030031 (0.1%). By RTX-denervation, we verified that non-neuronal TRPA1 also interferes in some inflammatory parameters induction. However, cutaneous nerve fibers seem to be most needed in the development of UVB radiation-induced inflammatory processes.

SIGNIFICANCE

We propose the TRPA1 channel participates in the UVB radiation-induced sunburn in mice, and it could be a promising therapeutic target to treat skin inflammatory disorders.

Antiarthritic Potential of Comprehensively Standardized Extract of Alternanthera bettzickiana: In Vitro and In Vivo Studies

Alternanthera bettzickiana is being used as a folk remedy for treating arthritis by conventional healers in Thailand. The current research was undertaken to explore the antiarthritic potential of A. bettzickiana ethanolic extract (ABEE). Plant characterization, molecular docking, and in vitro and in vivo (ABEE at 250, 500, and 1000 mg/kg was administered orally to rats once daily for 28 days) studies to explore the antiarthritic effect and enzyme-linked immunosorbent assay (ELISA) and real-time polymerase chain reaction (RT-PCR) analyses were performed. Oxidative stress biomarkers (superoxide dismutase (SOD), catalase (CAT), malondialdehyde (MDA)) in the serum and histopathological and radiographic assessment of joints were also carried out. Gallic acid, catechin, chlorogenic acid, sinapic acid, quercetin, and γ- and α-tocopherol were identified in high-performance liquid chromatography (HPLC). Molecular docking revealed a strong interaction between these compounds and cyclooxygenase (COX) enzymes. The extract significantly subdued paw swelling and arthritic scoring, inhibited cachexia, and considerably improved biochemical and hematological modifications. SOD and CAT levels increased and the MDA level decreased in ABEE-treated rats dose-dependently. Radiographic and histopathological analyses also supported the antiarthritic effect of ABEE, which was linked with the downregulation of nuclear factor (NF)-kB, COX-2, interleukin (IL)-6, tumour necrosis factor (TNF)-α, and IL-1β and upregulation of IL-10, I-kB, and IL-4 as compared to disease control rats. Results suggested that A. bettzickiana possessed antiarthritic potential, supporting its folkloric use for treating rheumatoid arthritis.

Monosodium urate crystal interleukin-1β release is dependent on Toll-like receptor 4 and transient receptor potential V1 activation

OBJECTIVE

The present study aimed to elucidate the mechanisms involved in MSU-induced IL-1β release in a rodent animal model of acute gout arthritis.

METHODS

Painful (mechanical and thermal hypersensitivity, ongoing pain and arthritis score) and inflammatory (oedema, plasma extravasation, cell infiltration and IL-1β release) parameters were assessed several hours after intra-articular injection of MSU (100 µg/articulation) in wild-type or knockout mice for Toll-like receptor 4 (TLR4), inducible nitric oxide synthase (iNOS), transient receptor potential (TRP) V1 and the IL-1 receptor (IL-1R). Also, wild-type animals were treated with clodronate, lipopolysaccharide from Rhodobacter sphaeroides (LPS-RS) (TLR4 antagonist), spleen tyrosine kinase (SYK) inhibitor (iSYK), aminoguanidine (AMG, an iNOS inhibitor) or SB366791 (TRPV1 antagonist). Nitrite/nitrate and IL-1β levels were measured on the synovial fluid of wild-type mice, 2 h after intra-articular MSU injections, or medium from macrophages stimulated for MSU (1000 μg) for 2 h.

RESULTS

Intra-articular MSU injection caused robust nociception and severe inflammation from 2 up to 6 h after injection, which were prevented by the pre-treatment with clodronate, LPS-RS, iSYK, AMG and SB366791, or the genetic ablation of TLR4, iNOS, TRPV1 or IL-1R. MSU also increased nitrite/nitrate and IL-1β levels in the synovial fluid, which was prevented by clodronate, LPS-RS, iSYK and AMG, but not by SB366791. Similarly, MSU-stimulated peritoneal macrophages released nitric oxide, which was prevented by LPS-RS, iSYK and AMG, but not by SB366791, and released IL-1β, which was prevented by LPS-RS, iSYK, AMG and SB366791.

CONCLUSION

Our data indicate that MSU may activate TLR4, SYK, iNOS and TRPV1 to induce the release of IL-1β by macrophages, triggering nociception and inflammation during acute gout attack.

Dexmedetomidine inhibits the invasion, migration, and inflammation of rheumatoid arthritis fibroblast-like synoviocytes by reducing the expression of NLRC5

Rheumatoid arthritis (RA) is a chronic, autoimmune disease characterized by inflammatory synovitis, but its pathogenesis remains unclear. NLRC5 is a newly discovered member of the NLR family that is effective in regulating autoimmunity, inflammatory responses, and cell death processes. Dexmedetomidine (DEX) has been reported to have a variety of pharmacological effects, including anti-inflammatory and analgesic effects. However, the role of DEX in RA has not been explored. In adjuvant-induced arthritis (AA) rat models, DEX (10 μg/kg and 20 μg/kg) reduced the pathological score, the arthritis score, paw swelling volume, and the serum levels of IL-1β, IL-6, IL-17A, and TNF-α. Moreover, by using Western blot and real-time quantitative PCR (RT-qPCR), it was demonstrated that DEX can inhibit the expression of IL-1β, IL-6, MMP-3, MMP-9 and P-P65 in the synovial tissue of AA rats. In human rheumatoid arthritis fibroblast-like synoviocytes (RA-FLSs), DEX (250 nM and 500 nM) was found to inhibit the expression of IL-1β, IL-6, MMP-3, MMP-9, and P-P65 following stimulation with TNF-α. Moreover, DEX can inhibit the invasion and migration of RA-FLSs stimulated by TNF-α. Finally, the expression of NLRC5 in RA-FLSs and AA rat models was also reduced by DEX. After silencing NLRC5 in RA-FLSs, the expression of IL-1β, IL-6, MMP-3, MMP-9, and P-P65, as well as the invasion and migration of cells, were significantly reduced. These results indicate that DEX inhibits the invasion, migration, and inflammation of RA-FLSs by reducing the expression of NLRC5 and inhibiting the NF-κB activation.

Emerging Roles for NLRC5 in Immune Diseases

Innate immunity activates the corresponding immune response relying on multiple pattern recognition receptors (PRRs) that includes pattern recognition receptors (PRRs), like NOD-like receptors (NLRs), RIG-I-like receptors (RLRs), and C-type lectin receptors (CLRs), which could accurately recognize invasive pathogens. In particular, NLRs belong to a large protein family of pattern recognition receptors in the cytoplasm, where they are highly correlated with activation of inflammatory response system followed by rapid clearance of invasive pathogens. Among the NLRs family, NLRC5, also known as NOD4 or NOD27, accounts for a large proportion and involves in immune responses far and wide. Notably, in the above response case of inflammation, the expression of NLRC5 remarkably increased in immune cells and immune-related tissues. However, the evidence for higher expression of NLRC5 in immune disease still remains controversial. It is noted that the growing evidence further accounts for the participation of NLRC5 in the innate immune response and inflammatory diseases. Moreover, NLRC5 has also been confirmed to exert a critical role in the control of regulatory diverse signaling pathways. Together with its broad participation in the occurrence and development of immune diseases, NLRC5 can be consequently treated as a potential therapeutic target. Nevertheless, the paucity of absolute understanding of intrinsic characteristics and underlying mechanisms of NLRC5 still make it hard to develop targeting drugs. Therefore, current summary about NLRC5 information is indispensable. Herein, current knowledge of NLRC5 is summarized, and research advances in terms of NLRC5 in characteristics, biological function, and regulatory mechanisms are reviewed.

MAST3 modulates the inflammatory response and proliferation of fibroblast-like synoviocytes in rheumatoid arthritis

Via promoting synovitis, pannus growth and cartilage/bone destruction, fibroblast-like synovial cells (FLSs) play a significant role in the pathogenesis of rheumatoid arthritis (RA). In our study, rats were induced with complete freund's adjuvant (CFA) to be animal models for studying the RA pathogenesis. Microtubule-associated Serine/Threonine-protein kinase 3 (MAST3) has been documented to play a critical role in regulating the immune response of IBD (Inflammatory bowel disease) and involved in the process of cytoskeleton organization, intracellular signal transduction and peptidyl-serine phosphorylation, but its role in the progression of RA remains unknown and is warranted for investigation. So, we tried our best to investigate the mechanism and signaling pathway of MAST3 in RA progression. In the synovial tissue and FLSs of AA rats, we have found that MAST3 was significantly up-regulated than normal. Furthermore, MAST3 overexpression could promote proliferation and inflammatory response of FLSs. In the aspect of mechanism, we discovered that the expression of MAST3 might involve in NF-κB signaling pathway in RA. On the whole, our results suggested that MAST3 might promote the proliferation and inflammation of FLSs by regulating NF-κB signaling pathway.

A novel NOX2 inhibitor attenuates human neutrophil oxidative stress and ameliorates inflammatory arthritis in mice

Neutrophil infiltration plays a significant pathological role in inflammatory diseases. NADPH oxidase type 2 (NOX2) is a respiratory burst oxidase that generates large amounts of superoxide anion (O₂^•−) and subsequent other reactive oxygen species (ROS). NOX2 is an emerging therapeutic target for treating neutrophilic inflammatory diseases. Herein, we show that 4-[(4-(dimethylamino)butoxy)imino]-1-methyl-1H-benzo[f]indol-9(4H)-one (CYR5099) acts as a NOX2 inhibitor and exerts a protective effect against complete Freund's adjuvant (CFA)-induced inflammatory arthritis in mice. CYR5099 restricted the production of O₂^•− and ROS, but not the elastase release, in human neutrophils activated with various stimulators. The upstream signaling pathways of NOX2 were not inhibited by CYR5099. Significantly, CYR5099 inhibited NOX2 activity in activated human neutrophils and in reconstituted subcellular assays. In addition, CYR5099 reduced ROS production, neutrophil infiltration, and edema in CFA-induced arthritis in mice. Our findings suggest that CYR5099 is a NOX2 inhibitor and has therapeutic potential for treating neutrophil-dominant oxidative inflammatory disorders.

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CYR5099 is a NOX2 inhibitor.

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CYR5099 inhibits human neutrophil respiratory burst and adhesion.

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CYR5099 reduces ROS production, neutrophil infiltration, and edema on mouse arthritis.

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CYR5099 has potential to treat neutrophil-mediated inflammatory diseases.

In situ hexagonal liquid crystal for intra-articular delivery of sinomenine hydrochloride

The aim of this study was to investigate the release behaviors of sinomenine hydrochloride loaded via in situ hexagonal liquid crystal (ISH), and its potential to improve the local bioavailability in knee joints of sinomenine hydrochloride (SMH) after intra-articular administration. The ISH was prepared by a liquid precursor mixture containing phytantriol (PT), Vitamin E acetate (VEA), ethanol (ET), and water. The in vitro release profiles revealed a sustained release of SMH from the optimized ISH formula (PT/VEA/ET/water, 60.8:3.2:16.0:20.0, w/w/w/w), which was selected for the in vivo pharmacokinetics and preliminary pharmacodynamics studies. In both healthy and adjuvant-induced arthritis (AA) rats, the SMH loaded ISH showed significantly smaller SMH AUC_0-∞ in plasma (P <  0.01), and higher SMH concentration in synoviums (2˜168 h) than that of SMH solution, indicating that the ISH significantly reduced the leakage of SMH into systemic circulation. The t_1/2α of SMH loaded ISH in the knee joints of AA rats, was longer (13.42 h) than that of healthy rats (1.34 h) (P < 0.05), most likely that in vivo drug release behavior of SMH loaded ISH was affected by the physiological environment of the joint. It was found that the SMH loaded ISH could benefit AA-rats by suppressing the level of IL-1β in comparison to SMH solutions. The results of the histopathology of knee joints in AA rats displayed that the SMH loaded ISH might be suitable for the development of treatment strategies for rheumatoid arthritis diseases.

TRPA1 involvement in analgesia induced by Tabernaemontana catharinensis ethyl acetate fraction in mice

BACKGROUND

Ionic channels such as the transient receptor potential ankyrin 1 (TRPA1) are essential for the detection and transmission of painful stimuli. In this sense, new TRPA1 antagonists have been searched as analgesics.

PURPOSE

Preclinical studies support the antinociceptive activity of Tabernaemontana catharinensis ethyl acetate fraction (Eta), which has constituents previously identified as TRPA1 antagonists (gallic acid). It was verified for the first time the involvement of the TRPA1 on Eta's antinociceptive and anti-inflammatory effects in mice pain models.

STUDY DESIGN

It was evaluated the Eta's effect (0.01-100 mg/kg, oral route) on nociceptive (spontaneous nociception, mechanical and cold allodynia) and inflammatory (paw edema) parameters in pain models involved with TRPA1 activation.

METHODS

Firstly, it was investigated the ability of Eta to act on TRPA1 or TRPV1 channels (Ca²⁺influx and binding assays in mice spinal cords). Next, it was evaluated the Eta's antinociceptive and anti-inflammatory effects after intraplantar injection of TRPA1 agonists (hydrogen peroxide, cinnamaldehyde or allyl isothiocyanate) in male Swiss mice (30-35 g). Moreover, the Eta's antinociceptive effects were evaluated on complete Freund's adjuvant (CFA)-induced chronic inflammatory pain (CIP), postoperative pain and on paclitaxel-induced peripheral neuropathy (PIPN). Oxidative parameters were evaluated in mice paw utilized for CFA induced-CIP model.

RESULTS

Eta inhibited the TRPA1 agonist-induced Ca²⁺ influx [I_max= 72.4 ± 1.5%; IC₅₀= 0.023(0.004-0.125)µg/ml], but not TRPV1 agonist-induced, nor was able to displace [³H]-resiniferatoxin (TRPV1 agonist) binding. Eta (0.1-100 mg/kg) inhibited the spontaneous nociception [ID₅₀= 0.043(0.002-0.723)mg/kg], mechanical [ID₅₀= 7.417(1.426-38.570)mg/kg] and cold allodynia, and edema development caused by TRPA1 agonists. Moreover, Eta (100 mg/kg) prevented and reversed the CFA-induced CIP (I_max= 55.8 ± 13.7%, I_max= 80.4 ± 5.1%, respectively) and postoperative pain (I_max= 88.0 ± 11.6%, I_max= 51.3 ± 14.9%, respectively), been also effective in reversing the acute (I_max= 94.4 ± 12.4%) and chronic (I_max= 86.8 ± 8.6%) PIPN. These effects seem to occur by TRPA1 channels pathway, and independently of TRPV1 or oxidative mechanisms.

CONCLUSION

Our results demonstrate that Eta-induced antinociception and anti-inflammatory effects occur by TRPA1 inhibition making possible the use of this preparation as a potential therapeutic agent to treat pathological pains.

PSTPIP2 Inhibits the Inflammatory Response and Proliferation of Fibroblast-Like Synoviocytes in vitro

Rheumatoid arthritis (RA) is a chronic autoimmune inflammatory disease and its pathogenesis remains unclear. Fibroblast-like synoviocytes (FLSs) play an important role in the pathogenesis of RA. Proline-serine-threonine phosphatase interacting protein 2 (PSTPIP2) is an adaptor protein, which is associated with auto-inflammatory disease. In this study, we selected adjuvant-induced arthritis (AIA) as animal model to study the role of PSTPIP2 in FLSs. We found that the expression of PSTPIP2 was significantly down-regulated in synovial tissues and FLSs of AIA rat compared with normal group. And overexpression of PSTPIP2 could inhibit the proliferation and inflammatory response of FLSs. Moreover, the proliferation and inflammatory response of FLSs were promoted with PSTPIP2 silencing treatment. In terms of mechanism, we found that the expression of PSTPIP2 was closely related to NF-κB signaling pathway. Overall, our results suggested that PSTPIP2 inhibits the proliferation and inflammatory response of FLSs, which might be closely related to NF-κB signaling pathway.

Antioxidant and Oxidative Stress: A Mutual Interplay in Age-Related Diseases

Aging is the progressive loss of organ and tissue function over time. Growing older is positively linked to cognitive and biological degeneration such as physical frailty, psychological impairment, and cognitive decline. Oxidative stress is considered as an imbalance between pro- and antioxidant species, which results in molecular and cellular damage. Oxidative stress plays a crucial role in the development of age-related diseases. Emerging research evidence has suggested that antioxidant can control the autoxidation by interrupting the propagation of free radicals or by inhibiting the formation of free radicals and subsequently reduce oxidative stress, improve immune function, and increase healthy longevity. Indeed, oxidation damage is highly dependent on the inherited or acquired defects in enzymes involved in the redox-mediated signaling pathways. Therefore, the role of molecules with antioxidant activity that promote healthy aging and counteract oxidative stress is worth to discuss further. Of particular interest in this article, we highlighted the molecular mechanisms of antioxidants involved in the prevention of age-related diseases. Taken together, a better understanding of the role of antioxidants involved in redox modulation of inflammation would provide a useful approach for potential interventions, and subsequently promoting healthy longevity.

Current Approaches Including Novel Nano/Microtechniques to Reduce Silicone Implant-Induced Contracture with Adverse Immune Responses

Capsular contracture, which is the pathologic development of fibrous capsules around implants, is a major complication of reconstructive and aesthetic breast surgeries. Capsular contracture can cause implant failure with breast hardening, deformity, and severe pain. The exact mechanisms underlying this complication remain unclear. In addition, anaplastic large cell lymphoma is now widely recognized as a very rare disease associated with breast implants. Foreign body reactions are an inevitable common denominator of capsular contracture. A number of studies have focused on the associated immune responses and their regulation. The present article provides an overview of the currently available techniques, including novel nano/microtechniques, to reduce silicone implant-induced contracture and associated foreign body responses.

NLRC5 promotes cell proliferation via regulating the NF-κB signaling pathway in Rheumatoid arthritis

Rheumatoid arthritis (RA) is a chronic autoimmune inflammatory disease and the pathogenesis remains unclear. Previous studies suggested that fibroblast-like synoviocytes (FLSs) play an important role in RA pathogenesis, including the injury of cartilage, the hyperplasia of the synovium and the release of inflammatory cytokines. We used complete Freund's adjuvant (CFA) induced rats as animal models for studying the RA pathogenesis. NLRC5 as the largest member of the NLR family has been reported to play a critical role in regulating immune responses. Increasing evidence suggests that NLRC5 is an pivotal negative modulator of inflammatory pathways. We investigated the mechanisms and signaling pathways of NLRC5 in RA progression. Significantly increased expression of NLRC5 was found in AA rats synovial tissues and cells. And high expression of inflammatory cytokine and cell proliferation of FLSs accompanied with NLRC5 overexpression, but inhibited in cells with NLRC5 silencing treatment. Interestingly, we found that overexpression of NLRC5 also coordinated the activation of NF-κB signaling pathway. These results suggested that NLRC5 promotes RA progression via the NF-κB signaling pathway potentially.

In Vivo Detection of the Effect of Electroacupuncture on "Zusanli" Acupoint in Rats with Adjuvant-Induced Arthritis through Optical Coherence Tomography

This study aimed to investigate the effect of electroacupuncture (EA) treatment through optical coherence tomography (OCT) in vivo on rats with adjuvant-induced arthritis. OCT images were obtained from the ankle of the right hind paws of the rats in control, model, and EA groups before modelling and 1 day, 8 days, 15 days, 22 days, and 29 days after modelling. Results demonstrated that the OCT signal of the ankle of the right hind paws of the rats was indistinct compared to 1 day after modelling and before modelling in the EA group. In the EA group, the light averaged attenuation coefficients of the ankle tissues decreased as treatment duration was prolonged after EA was administered (3.43, 2.96, 2.61, 2.42, and 2.29 mm⁻¹, resp.). There was a significant difference in attenuation coefficient decrease between the 29th d and the 1st d for EA group compared with control group (P < 0.01). This condition indicated that the light absorption of the ankle of the treated rats in the EA group decreased. Therefore, OCT can be used to monitor the effect of treatment on rats with arthritis in vivo.

Antinociceptive and antidepressant-like effects of the crude extract of Vitex megapotamica in rats

ETHNOPHARMACOLOGICAL RELEVANCE

Vitex megapotamica (Spreng) Moldenke has been used in South American folk medicine to treat inflammatory diseases. However, the effects of V. megapotamica on animal models of nociception and depression have not been evaluated.

AIM OF THE STUDY

This study investigated whether the crude leaf extract of V. megapotamica exhibits antinociceptive and antidepressant-like effects in a Freund's adjuvant-induced chronic inflammation and depression model.

MATERIALS AND METHODS

Chronic inflammation was induced in rats by the intraplantar administration of complete Freund's adjuvant (CFA; 100μl). The effect of oral crude extract of V. megapotamica (VmE; 3-30mg/kg, p.o.) on nociception (thermal hyperalgesia, mechanical allodynia and arthritis score), inflammation (edema, myeloperoxidase activity), immobility (forced swimming test), locomotor activity (open field), gastrointestinal transit, hyperalgesia and naloxone-precipitated morphine withdrawal syndrome was evaluated. Naloxone (0.4mg/kg, i.p.) was used to investigate the involvement of opioid system in the currently described effects of VmE.

RESULTS

Crude extract caused antinociceptive/antidepressant-like effects in the CFA-induced chronic inflammation model, which was prevented by naloxone. The VmE extract (10mg/kg, p.o.) did not alter the locomotor activity, gastrointestinal function and inflammatory parameters and did not cause hyperalgesia.

CONCLUSION

V. megapotamica induces opioid-dependent antinociception and antidepressant-like effect, without anti-inflammatory activity. The results support the use of VmE as analgesic and antidepressant.

Tabernaemontana catharinensis ethyl acetate fraction presents antinociceptive activity without causing toxicological effects in mice

ETHNOPHARMACOLOGICAL RELEVANCE

Tabernaemontana catharinensis (Apocynaceae) is a medicinal plant used for the treatment of painful and inflammatory disorders. Here, we investigated the antinociceptive potential of the ethyl acetate fraction (Eta) from T. catharinensis leaves and assessed its toxic effects in mice to validate its popular use.

MATERIALS AND METHODS

Adult male Swiss mice (30-35g) were used. The Eta antinociceptive effect (200-800mg/kg, oral route (p.o.)) was evaluated in the acetic acid, formalin, capsaicin and tail-immersion tests. Adverse effects were analyzed using rotarod and open-field tests, body temperature, biochemical analysis and gastric lesions assessment. To evaluate the acute (OECD 423) or sub-acute (OECD 407) toxicity of the Eta, it was administered orally at a single (2000mg/kg) or repeated doses (100-400mg/kg/day for 28 days), respectively. Mortality, behavioral changes, biochemical and hematological parameters were evaluated. The Eta effect on cellular viability also was evaluated.

RESULTS

Eta (200-800mg/kg) inhibited the nociception caused by acetic acid (93.9±1.5%), formalin (86.2±10.8%) or capsaicin (75.4±3.3%) without inducing gastric lesions. Moreover, Eta neither altered the body temperature, biochemical parameters, nor forced or spontaneous locomotor activity of mice. The acute administration of the Eta (2000mg/kg) promoted a decrease in blood glucose levels and alanine aminotransferase activity. In the sub-acute toxicity study, Eta increased the aspartate aminotransferase activity (400mg/kg) and platelet distribution width (200mg/kg). Furthermore, Eta did not alter the cellular viability in cortical slices.

CONCLUSIONS

Eta presents antinociceptive effects and mild toxicity in mice. These results support its traditional use as a potential analgesic.

Long-Term Treatment by Vitamin B1 and Reduction of Serum Proinflammatory Cytokines, Hyperalgesia, and Paw Edema in Adjuvant-Induced Arthritis

INTRODUCTION

Immune system is involved in the etiology and pathophysiology of inflammation and vitamins are important sources of substances inducing nonspecific immunomodulatory effects. Given the proinflammatory role of cytokines in the inflammation and pain induction, this study aimed to assess the effects of long-term administration of vitamin B₁ on the proinflammatory cytokines, edema, and hyperalgesia during the acute and chronic phases of adjuvant-induced arthritis.

METHODS

On the first day of study, inflammation was induced by intraplantar injection of complete Freund's adjuvant (CFA) in the hindpaws of rats. Vitamin B₁ at doses of 100, 150, and 200 mg/kg was administrated intraperitoneally during 21 days of the study. Antinociceptive and anti-inflammatory effects of vitamin B₁ were also compared to indomethacin (5 mg/kg). Inflammatory symptoms such as thermal hyperalgesia and paw edema were measured by radiant heat and plethysmometer, respectively. Serum TNF-α and IL-1β levels were checked by rat standard enzyme-linked immune sorbent assay (ELISA) specific kits.

RESULTS

The results indicated that vitamin B₁(150 and 200 mg/kg) attenuated the paw edema, thermal hyperalgesia, and serum levels of TNF-α and IL-1β during both phases of CFA-induced inflammation in a dose-dependent manner. Effective dose of vitamin B₁(150 mg/kg) reduced inflammatory symptoms and serum levels of TNF-α and IL-1β compare to indomethacin during the chronic phase of inflammation.

CONCLUSION

Anti-inflammatory and antihyperalgesic effects of vitamin B1 during CFA-induced arthritis, more specifically after chronic vitamin B₁ administration, suggest its therapeutic property for inflammation.

Analgesic effects of NB001 on mouse models of arthralgia

Our previous studies have demonstrated the critical roles of calcium-stimulated adenylyl cyclase 1 (AC1) in the central nervous system in chronic pain. In the present study, we examined the analgesic effects of NB001, a selective inhibitor of AC1, on animal models of ankle joint arthritis and knee joint arthritis induced by complete Freund’s adjuvant injection. NB001 treatment had no effect on joint edema, stiffness, and joint destruction. Furthermore, the treatment failed to attenuate the disease progression of arthritis. However, NB001 treatment (3 mg/kg) significantly weakened joint pain-related behavior in the mouse models of ankle joint arthritis and knee joint arthritis. Results indicated that NB001 exhibited an analgesic effect on the animal models of arthritis but was not caused by anti-inflammatory activities.