Aliskiren, tadalafil, and cinnamaldehyde alleviate joint destruction biomarkers; MMP-3 and RANKL; in complete Freund's adjuvant arthritis model: Downregulation of IL-6/JAK2/STAT3 signaling pathway

Experimental verification of Myriocin molecular bioactivity in revoking rheumatoid arthritis: New emphasis on S100A1 repression and PPAR-γ activation via non-canonical pathways in the flare-up of cytokines

Myriocin (MYR), the immunosuppressive agent isolated from Mycelia sterilia is recently nominated as a potential therapy for various inflammatory disorders. This work is a primary insight on the mechanistic pathways for its potential anti-arthritic effect against complete Freund's adjuvant-induced arthritis in mice. First day double injection of 0.1 ml adjuvant, followed by a single booster dose in the second day provoked arthritis after 5 weeks. Initiation of treatment with MYR (0.4 mg/kg, i.p.) and the anti-arthritic drug; methotrexate (MT, 0.75 mg/kg, i.p., 3 times/week) was commenced from day 10 to the end of the study. MYR, similar to MT, mitigate arthritis progression through distinct lowering in serum rheumatoid factor, arthritis index, paw thickness, and lessen joint inflammation and destruction in limb architecture. MYR inhibited S100A1/TLR4 signaling, thus, reduced IL-23 generation and subsequent IL-17 production. MYR exerted additional anti-inflammatory effects via marked reduction in NF-κBp65, TNF-α, IL-1β, IL-6, and COX-2 tissue levels. These effects are linked with myriocin-induced PPAR-γ stimulatory actions, thus explaining the transrepression between PPAR-γ, S100A1/TLR4/NF-κB and IL-23/IL-17 signaling, with emphasizing the central role of PPAR-γ activation in the connection between multiple pathways. In view of these results, myriocin could be a possible innovative cure for immune/inflammatory disorders as rheumatoid arthritis.

Inhibitor of differentiation-2 protein ameliorates complete Freund's adjuvant-induced arthritis and inhibits STAT3 phosphorylation in the synovium

Rheumatoid arthritis (RA) is a chronic autoimmune disease causing joint inflammation, dysfunction, and deformity, along with systemic inflammatory manifestations. Inhibitor of differentiation-2 (ID2) is a transcription factor containing a helix-loop-helix (HLH) structure. Studies suggest that ID2 regulates innate and adaptive immunity and inhibits the differentiation of osteoclasts. However, the effects and underlying molecular mechanisms of ID2 on rheumatoid arthritis (RA) remain unclear. In the present study, we found that exogenous supplementation of human recombinant ID2 (hID2) protein significantly reduced paw swelling and arthritis index scores in adjuvant-induced arthritis (AIA) rats, and improved ankle joint pathology. Analysis of pro-inflammatory factor levels in peripheral blood mononuclear cells and synovial tissues indicated that hID2 attenuated inflammatory responses in AIA rats. Furthermore, RNA sequencing demonstrated that hID2 down-regulated the JAK-STAT pathway, and the phosphorylation of its key molecule, Signal Transducer and Activator of Transcription 3 (STAT3), was inhibited in synovial tissues. Additionally, the expression of chemokine-related genes was noticeably down-regulated in synovial tissues, though further investigation is needed to understand the underlying mechanisms. Overall, these findings suggest that hID2 effectively attenuated the inflammatory response and joint destruction in AIA rats, highlighting the potential of hID2 as a therapeutic agent for the treatment of RA.

Regulation of renal nitric oxide and eNOS/iNOS expression by tadalafil participates in the mitigation of amphotericin B-induced renal injury: Down-regulation of NF-κB/iNOS/caspase-3 signaling

Amphotericin B (AmB)-induced acute kidney injury (AKI) is a common health problem having an undesirable impact on its urgent therapeutic utility for fatal systemic fungal infections. Tadalafil (TAD), a phosphodiesterase-5 (PDE-5) inhibitor, has been observed to have a wide range of pharmacological actions, including nephroprotection. The study's objective was to examine the possible underlying protective mechanism of TAD against AmB-induced nephrotoxicity. Experimentally, animals were divided randomly into four groups: control, TAD (5 mg/kg/day; p.o.), AmB (18.5 mg/kg/day; i.p.), and TAD+AmB groups. Sera and tissue samples were processed for biochemical, molecular, and histological analyses. The biochemical investigations showed that TAD significantly ameliorated the increase of kidney function biomarkers (creatinine, urea, CysC, KIM-1) in serum, renal nitric oxide (NO), lipid peroxidation (MDA), and inflammatory cytokines (TNF-α, IL-6) in AmB-treated rats. Meanwhile, TAD significantly retarded AmB-induced decrease in serum magnesium, sodium, potassium, and renal glutathione content. Molecular analysis revealed that TAD reduced AmB-induced imbalance in the protein expression of eNOS/iNOS, which explains its regulatory effect on renal NO content. These results were also supported by the down-regulation of nuclear NF-κB p65 and cleaved caspase-3 protein expressions, as well as the improvement of histological features by TAD in AmB-treated rats. Therefore, it can be suggested that TAD could be a promising candidate for renoprotection against AmB-induced AKI. That could be partly attributed to its regulatory effect on renal eNOS/iNOS balance and NO, the inhibition of NF-κB p65 nuclear translocation, its downstream inflammatory cytokines and iNOS, and ultimately the inhibition of caspase-3-induced renal apoptosis.

Nitric Oxide Synthases in Rheumatoid Arthritis

Rheumatoid arthritis (RA) is an autoimmune disease characterized by severe joint damage and disability. However, the specific mechanism of RA has not been thoroughly clarified over the past decade. Nitric oxide (NO), a kind of gas messenger molecule with many molecular targets, is demonstrated to have significant roles in histopathology and homeostasis. Three nitric oxide synthases (NOS) are related to producing NO and regulating the generation of NO. Based on the latest studies, NOS/NO signaling pathways play a key role in the pathogenesis of RA. Overproduction of NO can induce the generation and release of inflammatory cytokines and act as free radical gas to accumulate and trigger oxidative stress, which can involve in the pathogenesis of RA. Therefore, targeting NOS and its upstream and downstream signaling pathways may be an effective approach to managing RA. This review clearly summarizes the NOS/NO signaling pathway, the pathological changes of RA, the involvement of NOS/NO in RA pathogenesis and the conventional and novel drugs based on NOS/NO signaling pathways that are still in clinical trials and have good therapeutic potential in recent years, with an aim to provide a theoretical basis for further exploration of the role of NOS/NO in the pathogenesis, prevention and treatment of RA.

Panlongqi tablet suppresses adjuvant-induced rheumatoid arthritis by inhibiting the inflammatory reponse in vivo and in vitro

ETHNOPHARMACOLOGICAL RELEVANCE

Panlongqi Tablet is prepared with the ancestral secret recipe provided by Mr. Wang Jiacheng, a famous specialist in orthopedics and traumatology of China. The efficacy and safety of PLQT have been supported by years of clinical practice in the treatment of joint-related conditions. Has remarkable effect for treating rheumatoid arthritis (RA) clinically. However, its mechanism is not entirely clear.

AIM OF THE STUDY

We aim to evaluate the anti-inflammatory activity of PLQT and explore its mechanism in adjuvant-induced arthritis (AA) mice and LPS-induced Human fibroblast-like synovial (HFLS) cells.

MATERIALS AND METHODS

To this end, we analyzed the active ingredients in PLQT by HPLC-MS/MS. Furthermore, the anti-RA effect of PLQT was studied through proliferation, apoptosis, foot swelling, cytokine levels, immune organ index, histopathology and related signal pathways in LPS-induced HFLS cells and AA-treated mice.

RESULTS

HPLC-MS/MS results showed that PLQT contained a variety of active compounds, such as epicatechin, imperatorin, hydroxysafflor yellow A and so on. PLQT significantly inhibited the abnormal proliferation of HFLS cells induced by LPS, promoted cell apoptosis. In AA-treated mice, PLQT alleviated RA symptoms by alleviating paw swelling, synovial hyperplasia, pannus formation, inflammatory cell infiltration, and inhibiting abnormal immune responses. The results showed that PLQT significantly decreased the expression of inflammatory mediators (IL-1β, IL-6, IL-17) in vivo and in vitro, which may be related to the regulation of PI3K/Akt, MAPK and JAK/STAT signaling pathways.

CONCLUSION

Based on serum pharmacology and in vivo pharmacology studies, PLQT may regulate RA symptoms by regulating inflammatory and immune response-related pathways, which is an effective method for the treatment of RA.

Euphorbium total triterpenes improve Freund's complete adjuvant-induced arthritis through PI3K/AKT/Bax and NF-κB/NLRP3 signaling pathways

ETHNOPHARMACOLOGICAL RELEVANCE

Euphorbium is the resinous secretion of Euphorbia resinifera Berg. According to the record, Euphorbium was first used by Roman doctors to treat the emperor's joint pain. In China, it is applied in folk medicine to treat damp-cold or mucous diseases, such as arthralgia and ascites, etc. This herb is used for rheumatoid arthritis and skin tumors in the folklore of northeastern Brazil. Triterpenes are mainly characteristic constituents of Euphorbium, and possibly possess anti-rheumatoid arthritis.

AIM OF THE STUDY

To explore the preventive effect of Euphorbium total triterpenes (TTE) on Freund's complete adjuvant (FCA) induced arthritis in rats and its mechanism.

MATERIAL AND METHODS

TTE was extracted and isolated from Euphorbium, and its components were analyzed by HPLC. The safety of TTE was evaluated by an acute toxicity test in mice. Arthritis was induced in rats by injecting 0.2 mL FCA into the right hind paw toe, except for the control group, which was given the same volume of physiological saline. Tripterygium Glycosides (TG, 7.5 mg/kg) and TTE (32, 64 and 128 mg/kg) were administered by gavage for 30 days. Body weights, paw swelling, and arthritic scores were measured during the experiment process. After 30 days, blood and joints were harvested to determine various indicators of arthritis.

RESULTS

The contents of euphol and euphorbol in TTE were 47.03% and 18.77% respectively, and the maximal feasible dose of TTE in mice is 12 g/kg. The experimental results showed that arthritis indicators in rats deteriorated after FCA inducement compared with the control group. After treatment with TTE, the swelling degree and histopathological change of the hind paws in rats were significantly improved as well as arthritic score; the serum TNF-α, CRP, IL-1β, IL-6, IL-18 and RF levels in rats were significantly reduced; The expression of PI3K, AKT, P-AKT, Bcl-2, NF-κB, NLRP3 and Pro-caspase-1 protein in joint tissue were down-regulated, and the expression of Bax protein was up-regulated.

CONCLUSION

The results suggested that TTE possessed anti-arthritis effects, and its mechanism may be related to its anti-inflammatory and immunomodulatory properties, as well as regulation of PI3K/AKT/Bax and NF-κB/NLRP3 signaling pathway.

Molecular Basic of Pharmacotherapy of Cytokine Imbalance as a Component of Intervertebral Disc Degeneration Treatment

Intervertebral disc degeneration (IDD) and associated conditions are an important problem in modern medicine. The onset of IDD may be in childhood and adolescence in patients with a genetic predisposition. With age, IDD progresses, leading to spondylosis, spondylarthrosis, herniated disc, spinal canal stenosis. One of the leading mechanisms in the development of IDD and chronic back pain is an imbalance between pro-inflammatory and anti-inflammatory cytokines. However, classical therapeutic strategies for correcting cytokine imbalance in IDD do not give the expected response in more than half of the cases. The purpose of this review is to update knowledge about new and promising therapeutic strategies based on the correction of the molecular mechanisms of cytokine imbalance in patients with IDD. This review demonstrates that knowledge of the molecular mechanisms of the imbalance between pro-inflammatory and anti-inflammatory cytokines may be a new key to finding more effective drugs for the treatment of IDD in the setting of acute and chronic inflammation.

Glucocorticoid-loaded pH/ROS Dual-Responsive Nanoparticles Alleviate Joint Destruction by Downregulating the NF-κB Signaling Pathway

Rheumatoid arthritis (RA) is an autoimmune disease causing severe symptoms that are difficult to treat. Nano-drug delivery system is recognized as a promising strategy for management of RA. However, how to thoroughly release payloads from nanoformulations and synergistic therapy of RA needs to be further investigated. To address this issue, a pH and reactive oxygen species (ROS) dual-responsive, methylprednisolone (MPS)-loaded and arginine-glycine-aspartic acid (RGD)-modified nanoparticles (NPs) were fabricated using phytochemical and ROS-responsive moiety co-modified α-cyclodextrin (α-CD) as a carrier. In vitro and in vivo experiments verified that the pH/ROS dual-responsive nanomedicine could be efficiently internalized by activated macrophages and synovial cells, and the released MPS could promote transformation of M1-type macrophages into M2 phenotype, thereby down-regulating pro-inflammatory cytokines. In vivo experiments demonstrated that the pH/ROS dual-responsive nanomedicine was remarkably accumulated in the inflamed joints of mice with collagen-induced arthritis (CIA). The accumulated nanomedicine could obviously relieve joint swelling and cartilage destruction without obvious adverse effects. Importantly, the expression of interleukin-6 and tumor necrosis factor-α in the joints of CIA mice were significantly inhibited by the pH/ROS dual-responsive nanomedicine in comparison with free drug and non-targeted counterparts. In addition, the expression of the NF-κB signaling pathway molecules P65 was also significantly decreased by nanomedicine-treatment. Our results reveal that MPS-loaded pH/ROS dual-responsive NPs can effectively alleviate joint destruction via down-regulation of the NF-κB signaling pathway. STATEMENT OF SIGNIFICANCE: Nanomedicine is recognized as an attractive method for the targeting treatment of rheumatoid arthritis (RA). To thorough release of payloads from nanoformulations and synergistic therapy of RA, herein, a phytochemical and ROS-responsive moiety co-modified α-cyclodextrin was used as a pH/ROS dual-responsive carrier to encapsulate methylprednisolone to manage RA. The fabricated nanomedicine can effectively release its payloads under pH and/or ROS microenvironment, and the released drugs dramatically promote transformation of M1-type macrophages into M2 phenotype to reduce the release of pro-inflammatory cytokines. The prepared nanomedicine also obviously decreased the NF-κB signaling pathway molecule P65 expression in the joints, thereby down-regulating pro-inflammatory cytokines expression to alleviate joint swelling and cartilage destruction. We provided a candidate for the targeting treatment of RA.

Network pharmacology-based analysis of the mechanism of Saposhnikovia divaricata for the treatment of type I allergy

CONTEXT

Saposhnikovia divaricata (Turcz.) Schischk (Apiaceae) (SD) has various pharmacological activities, but its effects on type I allergy (TIA) have not been comprehensively studied.

OBJECTIVE

This study evaluates the treatment and molecular mechanisms of SD against TIA.

MATERIALS AND METHODS

The effective components and action targets of SD were screened using TCMSP database, and allergy-related targets of SD were predicted using GeneCards and OMIM database. The obtained target intersections were imported into David database for GO analysis, and used R software to perform KEGG analysis. The RBL-2H3 cells sensitised by DNP-IgE/DNP-BSA were treated with different concentrations of SD (root decoction, 0.5, 1, and 2 mg/mL), prim-O-glucosylcimifugin (POG, 10, 40, and 80 μg/mL) and the positive control drug-ketotifen fumarate (KF, 30 μM) for 12 h, then subjected to cell degranulation and qPCR analysis.

RESULTS

Eighteen active compounds of SD and 38 intersection targets were obtained: TIA-related signal pathways mainly include calcium signal pathway, PI3K-Akt signal pathway and MAPK signal pathway. Taking the β-Hex release rate of the model group as the base, the release rate of SD and POG in high dose groups were 43.79% and 57.01%, respectively, which were significantly lower than model group (p < 0.01), and significantly lower than KF group (63.83%, p < 0.01, p < 0.05). SD and POG could down-regulate the expression of related proteins in the Lyn/Syk, PI3K/AKT and MAPK signalling pathways.

DISCUSSION AND CONCLUSION

Saposhnikovia divaricata could inhibit IgE-induced degranulation of mast cells, providing a scientific basis for further research and clinical applications of SD in TIA treatment.

Recent advances in diverse nanosystems for nitric oxide delivery in cancer therapy

Gas therapy has been proven to be a promising and advantageous treatment option for cancers. Studies have shown that nitric oxide (NO) is one of the smallest structurally significant gas molecules with great potential to suppress cancer. However, there is controversy and concern about its use as it exhibits the opposite physiological effects based on its levels in the tumor. Therefore, the anti-cancer mechanism of NO is the key to cancer treatment, and rationally designed NO delivery systems are crucial to the success of NO biomedical applications. This review summarizes the endogenous production of NO, its physiological mechanisms of action, the application of NO in cancer treatment, and nano-delivery systems for delivering NO donors. Moreover, it briefly reviews challenges in delivering NO from different nanoparticles and the issues associated with its combination treatment strategies. The advantages and challenges of various NO delivery platforms are recapitulated for possible transformation into clinical applications.

Integrated Experimental Approach, Phytochemistry, and Network Pharmacology to Explore the Potential Mechanisms of Cinnamomi Ramulus for Rheumatoid Arthritis

Cinnamomi Ramulus (CR) has been extensively used as a remedy for inflammatory diseases in China. This study adopted an integrative approach of experimental research, phytochemistry, and network pharmacology to investigate its alleviative effects on rheumatoid arthritis (RA) and the underlying potential mechanisms. CR extract (50, 100, and 200 mg/kg) and methotrexate (MTX) significantly ameliorated RA symptoms in the collagen-induced arthritis (CIA) rat model. They also reduced paw volume, arthritis index, proinflammatory cytokines (TNF-α, IL-17A, IL-6, and IL-1β), and oxidative damage. Sixty-three compounds were systematically identified as the basic components of CR. Fifty-five common genes obtained from compounds and GEO databases were employed to construct the protein-protein interaction (PPI) network. Among them, 20 hub genes were identified via the cytoHubba. Enrichment analysis of the common genes indicated that the TNF signaling pathway and IL-17 signaling pathway might be the potential key pathways. Moreover, molecular docking methods confirmed the high affinity between the top 10 bioactive components of CR and the top 10 targets. In addition, in vitro results showed that CR extract (0.2, 0.4, and 0.8 mg/mL) inhibited inflammation and oxidative damage in MH7A cells stimulated by lipopolysaccharide (LPS). In summary, this study adopted multiple approaches to elucidate the protective effect and potential mechanisms of CR on RA, indicating that CR might be a promising herbal candidate for further investigation of RA treatment.

Role of ADMA/DDAH-1 and iNOS/eNOS signaling in the gastroprotective effect of tadalafil against indomethacin-induced gastric injury

Non-steroidal anti-inflammatory drugs (NSAIDs)-induced gastric ulcers represent a significant clinical concern and adversely affect the quality of life. Inducible nitric oxide synthase/endothelial nitric oxide synthase (iNOS/eNOS) and asymmetric dimethylarginine/ dimethylarginine dimethylaminohydrolase-1 (ADMA/DDAH-1) signaling are key players in gastric ulcer pathogenesis. This work was planned to explore the role of iNOS/eNOS and ADMA/DDAH-1 signaling in rats with indomethacin-induced gastric ulcer, as potential pathways for the gastro-protective effect of tadalafil. Split into 5 separate groups, rats were assigned to control, tadalafil (10 mg/kg, p.o), indomethacin (single oral dose of 60 mg/kg), indomethacin + pantoprazole (40 mg/kg, p.o), and indomethacin + tadalafil (10 mg/kg, p.o). The results indicated that pretreatment with tadalafil significantly reduced ulcer index (UI), increased preventive index (PI), and counteracted indomethacin-induced histopathological aberrations. Tadalafil significantly reduced the gastric content of NO while it significantly elevated that of GSH and enhanced SOD activity. It significantly reduced the gastric expression of TNF-α and ADMA while it significantly elevated that of COX-2, PGE-2, and DDAH-1. Western blot analysis revealed that pretreatment with tadalafil significantly reduced iNOS protein expression while it significantly elevated that of eNOS. Collectively, these data suggest that tadalafil exerts potential protective effect against indomethacin-induced ulcer through suppression of inflammation, attenuation of oxidative stress, and boosting of antioxidants. Moreover, tadalafil protective effects are mediated via upregulation of PGE-2 with modulating the signaling pathways of ADMA/DDAH-1, and iNOS/eNOS. As a result, the current evidence corroborates the use of tadalafil in controlling gastric ulcers and preventing NSAID gastric side effects.

Novel anti-arthritic mechanisms of trans-cinnamaldehyde against complete Freund's adjuvant-induced arthritis in mice: involvement of NF-кB/TNF-α and IL-6/IL-23/ IL-17 pathways in the immuno-inflammatory responses

Trans-cinnamaldehyde (TCA), a natural cinnamaldehyde derivative of cinnamon oil, is known for anti-inflammatory, anti-bacterial, anti-fungal, anti-diabetic, and anti-cancer activities. However, no study has examined the protective mechanisms of TCA on complete Freund's adjuvant (CFA)-induced arthritis. Chronic arthritis was induced in mice by triple dose injection of 0.1 ml CFA in the first two days, then a treatment with TCA (100 mg/kg, i.p.) and the anti-arthritic drug; methotrexate (MTX, 0.75 mg/kg, i.p., 3 times/week) started from day 10 after CFA and continued till day 35.TCA ameliorated the CFA-induced arthritis features, indicated by the decrease in serum rheumatoid factor, paw swelling, arthritis index and the arthritis changes in limb histology. Additionally, TCA treatment showed anti-inflammatory actions through downregulation of TNF-α, NF-κB and COX-2 expressions and marked reduction in IL-1β, IL-6, IL-23 and IL-17 levels in inflamed paw tissues.Consequently, TCA can decrease arthritis progression and inhibit the immune/inflammatory responses initiated by TNF-α/IL-1β/IL-6/IL-23/IL-17 signals, via NF-κB modulation, almost to the same extent accomplished by MTX. Therefore, TCA could be a promising anti-arthritic drug.

Fascin1 mediated release of pro-inflammatory cytokines and invasion/migration in rheumatoid arthritis via the STAT3 pathway

Rheumatoid arthritis (RA) is a chronic, multi-factorial disease characterized by Synovial hyperplasia, chronic inflammation, and autoimmune reaction. Fascin1 overexpression has been implicated in cancer, immune, and inflammatory diseases. However, the relationship between Fascin1 and rheumatoid arthritis (RA) has not yet been determined. We investigated whether Fascin1 could modulate pro-inflammatory cytokine secretion and the proliferation, apoptosis, and invasion/migration of fibroblast-like synoviocytes (RA-FLSs). Fascin 1 was suppressed with a short interfering (si)RNA approach. Functional analysis contained MTT assay, flow cytometry,Transwell™ assays, wound healing, Quantitative polymerase chain reaction and western blotting were used to detect cell proliferation,apoptosis ratio, invasion/ migration, the mRNA and protein expression of the realted markers, respectively. Overexpression of fascin1 was observed in RA-FLSs group compared with control group. Fascin1 expression positively correlated with changes in the expression of RA disease activity markers (RF, CRP, and DAB28, respectively). We also observed a significant positive correlation between Fascin1 and STAT3 mRNA levels in RA- FLSs.Fascin1 silencing attenuated the expression of pro-inflammatory cytokines; reduced FLS proliferation in vitro; and increased apoptosis ratio and bax, cleaved PARP, and caspase-3 expression. si- Fascin1 transfection delayed RA-FLS invasion/migration and reversed the epithelial- mesenchymal transition. These data suggest that Fascin1 exerts positive effects on the proliferation, cell cycle, and invasion/migration of RA-FLSs by activating signal transducer and activator of transcription 3 signaling.After all, Fascin1 contributed to RA development.

The role of renin angiotensin system in the pathophysiology of rheumatoid arthritis

BACKGROUND

In rheumatoid arthritis (RA) and osteoarthritis (OA), chronic inflammatory processes lead to progresive joint destruction. The renin-angiotensin system (RAS) is involved in the pathogenesis of RA and OA. The aim of this mini-review article is to summarize evidence on the role of RAS in RA and OA.

METHODS

A non-systematic search in Pubmed included terms as "rheumatoid arthritis", "renin angiotensin system", "osteopenia", "RANKL", "DKK-1", "MMP", "inflammation", "angiogenesis", "local renin-angiotensin system", "angiotensin converting enzyme", "AT2 receptor", "Ang-(1-7)", "VEGF", "angiotensine receptor blocker", "angiotensin converting enzyme inhibitors", "renin inhibitors".

RESULTS

Both RAS axes, the classical one, formed by angiotensin converting enzyme (ACE), angiotensin (Ang) II and AT1 receptor (AT1R) and the counter-regulatory one, composed by ACE2, Ang-(1-7) and the Mas receptor, modulate inflammation and tissue damage. Ang II activates pro-inflammatory mediators and oxidative stress. Conversely, Ang-(1-7) exerts anti-inflammatory actions, decreasing cytokine release, leukocyte attraction, density of vessels, tissue damage and fibrosis. Angiogenesis facilitates inflammatory cells invasion, while osteopenia causes joint dysfunction. Up-regulated osteoclastogenisis and down-regulated osteoblastogeneses were associaed with the activation of the classical RAS axis. Three different pathways, RANKL, DKK-1 and MMPs are enhanced by classical RAS activation. The treatment of RA included methotrexate and corticosteroids, which can cause side effects. Studies with angiotensin receptor blockers (ARBs), angiotensin converting enzyme inhibitors (ACEi) and renin inhibitors have been conducted in experimental and clinical RA with promising results.

CONCLUSION

The classical RAS activation is an important mechanism in RA pathogenesis and the benefit of ARB and ACEi administration should be further investigated.