The Natural Agonist of Estrogen Receptor β Silibinin Plays an Immunosuppressive Role Representing a Potential Therapeutic Tool in Rheumatoid Arthritis

Silibinin's Effects against Methotrexate-Induced Hepatotoxicity in Adjuvant-Induced Arthritis Rat Model

Methotrexate (MTX) is the first drug of choice to treat several diseases, including rheumatoid arthritis. However, its administration is accompanied by severe side effects, most commonly hepatotoxicity. Hence, alternative therapies with a lower toxicity and fewer side effects are needed. This study aimed to investigate the antioxidant and hepatoprotective effects of silibinin (SIL, natural agent) against MTX-induced hepatotoxicity in an adjuvant-induced arthritis (AIA) rat model. Arthritic rats were treated with SIL (100 mg/kg) and/or methotrexate (2 mg/kg). Non-arthritic rats, arthritic untreated rats, and arthritic rats who received the vehicle were followed in parallel. SIL alleviated the systemic consequences of arthritis by restoring lost weight, decreasing the erythrocyte sedimentation rate, and ameliorating joint damage, which was evident both micro- and macroscopically. Additionally, SIL prevented the histopathological alterations in the liver and significantly reduced the liver damage caused by MTX and AIA, as shown by a decrease in the markers of liver damage (ALT and AST). Furthermore, SIL relieved the oxidative stress induced by AIA and MTX in liver tissue by decreasing the lipid peroxidation (MDA) levels and enhancing the antioxidant defense system (GSH levels; catalase and superoxide dismutase (SOD) activities). In conclusion, our results suggest that SIL is a potent antioxidant and hepatoprotective agent in arthritic rats. It markedly attenuated the progression and severity of the arthritic disease and eased the oxidative stress in liver tissue by improving the pro-oxidant/antioxidant balance.

Ovarian sex steroid and epithelial control of immune responses in the uterus and oviduct: human and animal models†

The female reproductive tract (FRT), including the uterus and oviduct (Fallopian tube), is responsible for maintaining an optimal microenvironment for reproductive processes, such as gamete activation and transportation, sperm capacitation, fertilization, and early embryonic and fetal development. The mucosal surface of the FRT may be exposed to pathogens and sexually transmitted microorganisms due to the opening of the cervix during mating. Pathogens and endotoxins may also reach the oviduct through the peritoneal fluid. To maintain an optimum reproductive environment while recognizing and killing pathogenic bacterial and viral agents, the oviduct and uterus should be equipped with an efficient and rigorously controlled immune system. Ovarian sex steroids can affect epithelial cells and underlying stromal cells, which have been shown to mediate innate and adaptive immune responses. This, in turn, protects against potential infections while maintaining an optimal milieu for reproductive events, highlighting the homeostatic involvement of ovarian sex steroids and reproductive epithelial cells. This article will discuss how ovarian sex steroids affect the immune reactions elicited by the epithelial cells of the non-pregnant uterus and oviduct in the bovine, murine, and human species. Finally, we propose that there are regional and species-specific differences in the immune responses in FRT.

Silymarin Reduced Insulin Resistance in Non-Diabetic Women with Obesity

Silymarin has ameliorated obesity, type 2 diabetes (T2DM), and insulin resistance (IR) in combination with standard therapy, diet, or exercise in recent studies. Obesity and IR are the main risk factors for developing T2DM and other metabolic disorders. Today, there is a need for new strategies to target IR in patients with these metabolic diseases. In the present longitudinal study, a group of non-diabetic insulin-resistant women with type 1 and type 2 obesity were given silymarin for 12 weeks, with no change in habitual diet and physical activity. We used the Homeostatic Model Assessment for Insulin Resistance Index (HOMA-IR) to determine IR at baseline and after silymarin treatment (t = 12 weeks). We obtained five timepoint oral glucose tolerance tests, and other biochemical and clinical parameters were analyzed before and after treatment. Treatment with silymarin alone significantly reduced mean fasting plasma glucose (FPG) and HOMA-IR levels at 12 weeks compared to baseline values (p < 0.05). Mean fasting plasma insulin (FPI), total cholesterol, high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C), triglycerides (Tg), indirect bilirubin, and C-reactive protein (CRP) levels decreased compared to baseline values, although changes were non-significant. The overall results suggest that silymarin may offer a therapeutic alternative to improve IR in non-diabetic individuals with obesity. Further clinical trials are needed in this type of patient to strengthen the results of this study.

Silymarin and Inflammation: Food for Thoughts

Inflammation is a vital defense mechanism, creating hostile conditions for pathogens, preventing the spread of tissue infection and repairing damaged tissues in humans and animals. However, when inflammation resolution is delayed or compromised as a result of its misregulation, the process proceeds from the acute phase to chronic inflammation, leading to the development of various chronic illnesses. It is proven that redox balance disturbances and oxidative stress are among major factors inducing NF-κB and leading to over-inflammation. Therefore, the anti-inflammatory properties of various natural antioxidants have been widely tested in various in vitro and in vivo systems. Accumulating evidence indicates that silymarin (SM) and its main constituent silibinin/silybin (SB) have great potential as an anti-inflammation agent. The main anti-inflammatory mechanism of SM/SB action is attributed to the inhibition of TLR4/NF-κB-mediated signaling pathways and the downregulated expression of pro-inflammatory mediators, including TNF-α, IL-1β, IL-6, IL-12, IL-23, CCL4, CXCL10, etc. Of note, in the same model systems, SM/SB was able to upregulate anti-inflammatory cytokines (IL-4, IL-10, IL-13, TGF-β, etc.) and lipid mediators involved in the resolution of inflammation. The inflammatory properties of SM/SB were clearly demonstrated in model systems based on immune (macrophages and monocytes) and non-immune (epithelial, skin, bone, connective tissue and cancer) cells. At the same time, the anti-inflammatory action of SM/SB was confirmed in a number of in vivo models, including toxicity models, nonalcoholic fatty liver disease, ischemia/reperfusion models, stress-induced injuries, ageing and exercising models, wound healing and many other relevant model systems. It seems likely that the anti-inflammatory activities of SM/SB are key elements on the health-promoting properties of these phytochemicals.

Male violence disrupts estrogen receptor β signaling in the female hippocampus

Women are the main target of intimate partner violence (IPV), which is escalating worldwide. Mechanisms subtending IPV-related disorders, such as anxiety, depression and PTSD, remain unclear. We employed a mouse model molded on an IPV scenario (male vs. female prolonged violent interaction) to unearth the neuroendocrine alterations triggered by an aggressive male mouse on the female murine brain. Experimental IPV (EIPV) prompted marked anxiety-like behavior in young female mice, coincident with high circulating/cerebral corticosterone levels. The hippocampus of EIPV-inflicted female animals displayed neuronal loss, reduced BrdU-DCX-positive nuclei, decreased mature DCX-positive cells, and diminished dendritic arborization level in the dentate gyrus (DG), features denoting impaired neurogenesis and neuronal differentiation. These hallmarks were associated with marked down-regulation of estrogen receptor β (ERβ) density in the hippocampus, especially in the DG and dependent prosurvival ERK signaling. Conversely, ERα expression was unchanged. After EIPV, the DG harbored lowered local BDNF pools, diminished TrkB phosphorylation, and elevated glucocorticoid receptor phosphorylation. In unison, ERβ KO mice had heightened anxiety-like behavior and curtailed BDNF levels at baseline, despite enhanced circulating estradiol levels, while dying prematurely during EIPV. Thus, reiterated male-to-female violence jeopardizes hippocampal homeostasis in the female brain, perturbing ERβ/BDNF signaling, thus instigating anxiety and chronic stress.

Forecasting of potential anti-inflammatory targets of some immunomodulatory plants and their constituents using in vitro, molecular docking and network pharmacology-based analysis

Most synthetic immunomodulatory medications are extremely expensive, have many disadvantages and suffer from a lot of side effects. So that, introducing immunomodulatory reagents from natural sources will have great impact on drug discovery. Therefore, this study aimed to comprehend the mechanism of the immunomodulatory activity of some natural plants via network pharmacology together with molecular docking and in vitro testing. Apigenin, luteolin, diallyl trisulfide, silibinin and allicin had the highest percentage of C-T interactions while, AKT1, CASP3, PTGS2, NOS3, TP53 and MMP9 were found to be the most enriched genes. Moreover, the most enriched pathways were pathways in cancer, fluid shear stress and atherosclerosis, relaxin signaling pathway, IL-17 signaling pathway and FoxO signaling pathway. Additionally, Curcuma longa, Allium sativum, Oleu europea, Salvia officinalis, Glycyrrhiza glabra and Silybum marianum had the highest number of P-C-T-P interactions. Furthermore, molecular docking analysis of the top hit compounds against the most enriched genes revealed that silibinin had the most stabilized interactions with AKT1, CASP3 and TP53, whereas luteolin and apigenin exhibited the most stabilized interactions with AKT1, PTGS2 and TP53. In vitro anti-inflammatory and cytotoxicity testing of the highest scoring plants exhibited equivalent outcomes to those of piroxicam.

Ocimum sanctum L water extract: In-situ green synthesis of zinc oxide nanoparticles for treatment of rheumatoid arthritis: Preclinical study

BACKGROUND AND OBJECTIVE

Rheumatoid arthritis is a chronic progressive autoimmune disorder, characterised by destruction of cartilage and under line bones. Though exact etiology of rheumatoid arthritis (RA) remains unknown. It is believed that alteration in control of cellular or molecular responses is involved in the chronic inflammation. Earlier in RA patients it was observed the circulating RA specific biomarkers and immunoglobulin deposits in the synovial joints. Zinc Oxide Nanoparticles (ZnO NPs) is used as an anti-inflammatory and anticancer agent, however there is nil/very less scientific data shows the anti-arthritic activity of green synthesis ZnO nanoparticles (Ocimum sanctum water extract in-situ synthesis of ZnO NPs having active compound Caffeic acid and Rosmerinic acid). Hence, the present activity was planned to assess the anti-arthritic activity of ZnO NPs in CIA rats.

METHODS

Arthritis in rats were induced by subcutaneous injection of collagen type II (CII) (200 µl) at the base of tail on day 0 followed by booster dose on day 14. ZnO NPs were given (2 mg/kg b.wt./day) orally for 20 days. At the end of the study serum, joint homogenate was used to assess the level of biomarkers (RF, a-CCP, a-CII and CRP) and inflammatory mediators. In addition, m-RNA expression of various genes such as Nuclear factor-kB (NF-kB), inflammatory mediators like tumour necrosis factor-α (TNF-α), cyclooxygenase-2 (COX-2) etc. were assayed in joint tissue. Finally all these biochemical and molecular results were confirmed by microscopic study of joint tissue.

RESULTS

ZnO NPs, treated rats showed decrease in inflammation and clinical severity. This was related with decrease in the level of biomarkers (like RF, a-CCP and CRP), inflammatory mediators (TNF-α, COX-2) and activity of transcription factor NF-kB. All these findings were positively correlated with microscopic analysis of joint tissue that showed reduced inflammation and bone erosion in treated group.

CONCLUSION

This study validates the anti-arthritic activity of ZnO NPs as it mitigates the arthritis related symptoms in CIA rats.

Estrogenic flavonoids and their molecular mechanisms of action

Flavonoids are a major group of phytoestrogens associated with physiological effects, and ecological and social impacts. Although the estrogenic activity of flavonoids was reported by researchers in the fields of medical, environmental and food studies, their molecular mechanisms of action have not been comprehensively reviewed. The estrogenic activity of the respective classes of flavonoids, anthocyanidins/anthocyanins, 2-arylbenzofurans/3-arylcoumarins/α-methyldeoxybenzoins, aurones/chalcones/dihydrochalcones, coumaronochromones, coumestans, flavans/flavan-3-ols/flavan-4-ols, flavanones/dihydroflavonols, flavones/flavonols, homoisoflavonoids, isoflavans, isoflavanones, isoflavenes, isoflavones, neoflavonoids, oligoflavonoids, pterocarpans/pterocarpenes, and rotenone/rotenoids, was summarized through a comprehensive literature search, and their structure-activity relationship, biological activities, signaling pathways, and applications were discussed. Although the respective classes of flavonoids contained at least one chemical mimicking estrogen, the mechanisms varied, such as those with estrogenic, anti-estrogenic, non-estrogenic, and biphasic activities, and additional activities through crosstalk/bypassing, which exert biological activities through cell signaling pathways. Such mechanistic variations of estrogen action are not limited to flavonoids and are observed among other broad categories of chemicals, thus this group of chemicals can be termed as the "estrogenome". This review article focuses on the connection of estrogen action mainly between the outer and the inner environments, which represent variations of chemicals and biological activities/signaling pathways, respectively, and form the basis to understand their applications. The applications of chemicals will markedly progress due to emerging technologies, such as artificial intelligence for precision medicine, which is also true of the study of the estrogenome including estrogenic flavonoids.

Silibinin Attenuates Experimental Periodontitis by Downregulation of Inflammation and Oxidative Stress

Periodontitis is an oral microbiota-induced inflammatory disease, in which inflammation and oxidative stress play a critical role. Silibinin (SB), a Silybum marianum-derived compound, exhibits strong anti-inflammatory and antioxidative properties. We adopted a rat ligature-induced periodontitis model and a lipopolysaccharide- (LPS-) stimulated human periodontal ligament cells (hPDLCs) model to evaluate the protective effects of SB. In the in vivo model, SB reduced alveolar bone loss and apoptosis of PDLCs in the periodontal tissue. SB also maintained the expression of nuclear factor-E2-related factor 2 (Nrf2), a key regulator of cellular resistance to oxidative stress, and attenuated lipid, protein, and DNA oxidative damages in the periodontal lesion area. Meanwhile, in the in vitro model, SB administration reduced the production of intracellular reactive oxidative species (ROS). Furthermore, SB exerted a strong anti-inflammatory property in both in vivo and in vitro models by inhibiting the expression of inflammatory mediators including nuclear factor-κB (NF-κB) as well as nucleotide binding oligomerization domain- (NOD-) like receptor family pyrin domain-containing 3 (NLRP3) and downregulating the levels of proinflammatory cytokines. This study, for the first time, demonstrates that SB exhibits the anti-inflammatory and antioxidative properties against periodontitis by downregulating the expression of NF-κB and NLRP3 and upregulating Nrf2 expression, suggesting a promising potential clinical application of SB in periodontitis.

Role of reactive oxygen species and mitochondrial damage in rheumatoid arthritis and targeted drugs

Rheumatoid arthritis (RA) is an autoimmune disease characterized by synovial inflammation, pannus formation, and bone and cartilage damage. It has a high disability rate. The hypoxic microenvironment of RA joints can cause reactive oxygen species (ROS) accumulation and mitochondrial damage, which not only affect the metabolic processes of immune cells and pathological changes in fibroblastic synovial cells but also upregulate the expression of several inflammatory pathways, ultimately promoting inflammation. Additionally, ROS and mitochondrial damage are involved in angiogenesis and bone destruction, thereby accelerating RA progression. In this review, we highlighted the effects of ROS accumulation and mitochondrial damage on inflammatory response, angiogenesis, bone and cartilage damage in RA. Additionally, we summarized therapies that target ROS or mitochondria to relieve RA symptoms and discuss the gaps in research and existing controversies, hoping to provide new ideas for research in this area and insights for targeted drug development in RA.

Therapeutic Effects of Silibinin Against Polycystic Ovary Syndrome Induced by Letrozole in Rats via Its Potential Anti-Inflammatory and Anti-Oxidant Activities

Background

Current therapies for polycystic ovary syndrome (PCOS) are accompanied by unwanted effects. Silibinin; a flavonolignan has pleiotropic activities and favorable safety profile.

Purpose

To investigate the efficacy of silibinin on estrous cyclicity, inflammation, oxidative stress and ovarian morphology in letrozole-induced PCOS in rats.

Methods

Forty-eight female Wistar albino rats were divided into 2 sets. Rats of the first set (n = 12), assigned as a negative control (NC) received only the vehicle, rats of the second set (n = 36), assigned as PCOS rats, were given letrozole 1mg/Kg orally for 21 days. On day 21, six rats from the first set and six rats from the second set were euthanized for confirmation of PCOS-induction. The remaining animals from the first set assigned as group 1, those in the second set (n = 30) were equally divided into 5 groups and treated daily for 19 days as follows: group 2 (positive control) received only the vehicle, group 3 treated with metformin 300mg/Kg orally, groups 4 and 5 treated respectively with 100 and 200 mg/Kg silibinin intraperitoneally (IP), and group 6 treated with a combination of metformin 300mg/Kg orally and silibinin 100mg/Kg IP. On day 40, blood samples were examined for luteinizing hormone (LH), testosterone (TS) and estradiol (EST) levels, the anti-inflammatory and antioxidant parameters, ovarian and uterine morphology.

Results

Silibinin alone or in combination with metformin was found to be effective in restoring the regularity of estrous cycle by ameliorating the abnormal alterations of LH, TS, EST, tumor necrosis factor (TNF)-α, and oxidative status and by resuming the appearance of corpora lutea and decreasing or even total absence of cystic follicles in the ovaries.

Conclusion

Silibinin was effective in restoring estrous regularities and alleviating hormonal and histomorphological abnormalities of the ovarian and uterine tissues, this could be due to its anti-androgenic, anti-inflammatory and antioxidant properties.

Human Monocyte-Derived Dendritic Cells Are the Pharmacological Target of the Immunosuppressant Flavonoid Silibinin

Silibinin, a natural polyphenolic flavonoid, is known to possess anti-inflammatory, anticancer, antioxidant, and immunomodulatory properties. However, the effects of Silibinin on the maturation and immunostimulatory functions of human dendritic cells (DC) remain to be elucidated. In this study, we have attempted to ascertain whether Silibinin influences the maturation, cytokine production, and antigen-presenting capacity of human monocyte-derived DC. We show that Silibinin significantly suppresses the upregulation of costimulatory and MHC molecules in LPS-stimulated mature DC and inhibits lipopolysaccharide (LPS)-induced interleukin (IL)-12, IL-23, and TNF-α production. Furthermore, Silibinin impairs the proliferation response of the allogenic memory CD4 T lymphocytes elicited by LPS-matured DC and their Th1/Th17 profile. These findings demonstrate that Silibinin displays immunosuppressive activity by inhibiting the maturation and activation of human DC and support its potential application of adjuvant therapy in the treatment of autoimmune diseases.

What is the impact of sex hormones on the pathogenesis of rheumatoid arthritis?

Rheumatoid arthritis (RA) is the most common inflammatory rheumatic disease and has a female predominance of around 3:1. The relationship between sex hormones and RA has been of great interest to researchers ever since Philip Hench's observations in the 1930's regarding spontaneous disease amelioration in pregnancy. Extensive basic scientific work has demonstrated the immunomodulatory actions of sex hormones but this therapeutic potential has not to date resulted in successful clinical trials in RA. Epidemiological data regarding both endogenous and exogenous hormonal factors are inconsistent, but declining estrogen and/or progesterone levels in the menopause and post-partum appear to increase the risk and severity of RA. This review assimilates basic scientific, epidemiological and clinical trial data to provide an overview of the current understanding of the relationship between sex hormones and RA, focusing on estrogen, progesterone and androgens.

The Impact of Estrogens and Their Receptors on Immunity and Inflammation during Infection

Simple Summary

Human health is significantly affected by microbial infections. One of the largest determinants of the outcomes of such infections is the host immune response. Too weak of a response can lead to enhanced spread by the pathogen, while an overstimulated response can lead to immune-induced tissue damage. Thus, to effectively treat infected individuals, it is critical to understand the regulators that control inflammatory responses. Recently, it has become widely accepted that estrogens, a class of sex hormones, are capable of dramatically altering the responses of host cells to microbes. In this review, we discuss how estrogens change the host immune response, as well as how these changes can alter the outcome of the infection for the individual.

Abstract

Sex hormones, such as estrogen and testosterone, are steroid compounds with well-characterized effects on the coordination and development of vertebrate reproductive systems. Since their discovery, however, it has become clear that these “sex hormones” also regulate/influence a broad range of biological functions. In this review, we will summarize some current findings on how estrogens interact with and regulate inflammation and immunity. Specifically, we will focus on describing the mechanisms by which estrogens alter immune pathway activation, the impact of these changes during infection and the development of long-term immunity, and how different types of estrogens and their respective concentrations mediate these outcomes.

[The low expression of long non-coding RNA Linc00638 contributes to rheumatoid arthritis progression by regulating inflammation and oxidative stress]

OBJECTIVE

To investigate the expression of long non-coding RNA (lncRNA) Linc00638 in rheumatoid arthritis (RA) and its regulatory role in inflammation and oxidative stress of synovial fibroblasts in RA patients (RA-FLS).

METHODS

Peripheral blood mononuclear cells (PBMCs) were collected from 20 healthy individuals and 35 RA patients for detecting the expression of Linc00638 using RT-qPCR to analyze the correlation of Linc00638 expression with the clinical indicators of RA patients. A Linc00638 overexpression plasmid and siRNA targeting Linc00638 were transfected into RA-FLS, and the changes in cell viability was observed using CCK8 assay; the changes in the expression levels of interleukin-4 (IL-4), IL-6, reactive oxygen species (ROS) and superoxide dismutase (SOD) in the supernatant were detected using ELISA.

RESULTS

Compared with the healthy control subjects, RA patients had significantly increased ESR, CRP, RF, anti-CCP, IgA, and C4 levels (P < 0.05) and significantly decreased Linc00638 expression in the PBMCs (P < 0.01). The area under the receiver-operating characteristic (ROC) curve of Linc00638 was 91.86% with the best cut-off value of 0.74 for diagnosis of RA. Spearman correlation analysis showed that Linc00638 expression level was negatively correlated with age, course of disease, DAS28, ESR, CRP, RF and anti-CCP, and positively correlated with IL-4 and SOD levels (P < 0.05). Association rule analysis showed that a decreased Linc00638 expression was strongly correlated with an increase of age (>60 years), a longer disease course (>10 years), elevated levels of ESR, RF and anti-CCP, and decreased levels of IL-4 and SOD. In RA-FLS, overexpression of Linc00638 significantly inhibited while Linc00638 interference obviously enhanced the cell viability. Over-expression of Linc00638 also significantly increased the levels of IL-4 and SOD (P < 0.05) and decreased the expressions of IL-6 and ROS (P < 0.05), while interference of Linc00638 produced the opposite effects in the cells (P < 0.05).

CONCLUSION

RA patients have low expression levels of Linc00638, which may participate in disease progression by regulating inflammation and oxidative stress.

Phytochemicals in cancer and their effect on the PI3K/AKT-mediated cellular signalling

Protein kinases belong to the largest family of enzymes controlling every aspect of cellular activity including gene expression, cell division, differentiation and metabolism. They are part of major intracellular signalling pathways. Hence, it is not surprising that they are involved in the development of major diseases such as cardiovascular disorders, diabetes, dementia and, most importantly, cancer when they undergo mutations, modifications and unbalanced expression. This review will explore the possibility to draw a connection between the application of natural phytochemicals and the treatment of cancer. We have chosen to focus on the PI3K/AKT cellular signalling pathway which has been shown to be a major target by natural compounds in cell cultures and animal models.

Significant immunomodulatory and hepatoprotective impacts of Silymarin in MS patients: A double-blind placebo-controlled clinicaltrial

Interferon beta (IFN-β) has successfully been experimented with to treat multiple sclerosis (MS). However, patients sometimes do not respond effectively to treatment, and ‌adverse effects, including liver toxicity, accompany this therapy. ‌Accordingly, we decided to treat MS patients simultaneously with Silymarin (SM) as an immunomodulatory and hepatoprotective agent and IFN-β in a clinical trial study. Complete blood count (CBC), liver enzyme levels, and the serum concentration of inflammatory and anti-inflammatory cytokines were measured. Also, the frequency of immune cells was determined by flow cytometry. Liver enzyme levels were significantly lower in the intervention group (p < 0.05). The percentage of Th17 cells in the intervention group was significantly reduced compared to the placebo group (P < 0.001). Also, the frequency of Treg cells after treatment with SM plus IFN-β was significantly increased compared to the placebo group (p < 0.05). Furthermore, the IL-17 and IFN_γ cytokine levels were significantly reduced in the intervention group (p < 0.05). Moreover, the levels of anti-inflammatory cytokines IL-10 and TGF_β were significantly increased in the intervention group (P < 0.05).Overall, the results provide novel and supplementary information on SM's notable immunoregulatory effects on inflammatory response and liver function in MS patients. Clinical Trial Identifier Number: IRCTID: IRCT20171220037977N1.

Phyto-pharmacological perspective of Silymarin: A potential prophylactic or therapeutic agent for COVID-19, based on its promising immunomodulatory, anti-coagulant and anti-viral property

Coronavirus disease 2019 (COVID‐19) triggered by a new viral pathogen, named severe acute respiratory syndrome Coronavirus‐2 (SARS‐CoV‐2), is now a global health emergency. This debilitating viral pandemic not only paralyzed the normal daily life of the global community but also spread rapidly via global travel. To date there are no effective vaccines or specific treatments against this highly contagious virus; therefore, there is an urgent need to advocate novel prophylactic or therapeutic interventions for COVID‐19. This brief opinion critically discusses the potential of Silymarin, a flavonolignan with diverse pharmacological activity having antiinflammatory, antioxidant, antiplatelet, and antiviral properties, with versatile immune‐cytokine regulatory functions, that able to bind with transmembrane protease serine 2 (TMPRSS2) and induce endogenous antiviral cytokine interferon‐stimulated gene 15, for the management of COVID‐19. Silymarin inhibits the expression of host cell surface receptor TMPRSS2 with a docking binding energy corresponding to −1,350.61 kcal/mol and a full fitness score of −8.11. The binding affinity of silymarin with an impressive virtual score exhibits significant potential to interfere with SARS‐CoV‐2 replication. We propose in‐depth pre‐clinical and clinical review studies of silymarin for the development of anti‐COVID‐19 lead, based on its clinical manifestations of COVID‐19 and multifaceted bioactivities.

Si Miao San Attenuates Inflammation and Oxidative Stress in Rats with CIA via the Modulation of the Nrf2/ARE/PTEN Pathway

Objective

Si Miao San (SMS) is a traditional Chinese formula used in China to treat rheumatic diseases. To date, its mechanism in rheumatoid arthritis (RA) treatment is uncertain. Our study aims to assess the antiarthritic effects of SMS in experimental arthritic rats.

Materials and Methods

SMS (8.63, 4.31, and 2.16 g/kg/day) was orally administered after the first immunization from day 14 to day 53. The effects of SMS on rats with collagen-induced arthritis (CIA) were evaluated by arthritis score and histological assessment. The levels of cytokines and anti-CII antibodies in rat serum were measured by ELISAs. The expression of oxidative stress parameters was detected by biochemical assay kits. The levels of Nrf2, HO-1, NQO1, and PTEN were determined by western blotting.

Results

Medium- and high-dose SMS treatment significantly decreased arthritis scores and alleviated ankle joint histopathology in the rats with CIA. It inhibited the production of IL-6, TNF-α, COX-2, and PGE2 in rat serum. SMS also suppressed the expression of anti-CII antibodies IgG1 and IgG2a. Moreover, SMS significantly suppressed the levels of MDA and MPO in the synovial tissues while increasing the levels of SOD and CAT in the rats with CIA. The levels of Nrf2, HO-1, NQO1, and PTEN were upregulated by SMS in rat synovial tissues.

Conclusions

This study demonstrated that SMS effectively alleviated the disease progression of CIA by decreasing the levels of proinflammatory cytokines and reducing oxidative stress damage, as indicated by IL-6, TNF-α, COX-2, and PGE2 levels; inhibiting the overproduction of MDA and MPO; and enhancing antioxidant enzymes by upregulating the Nrf2/ARE/PTEN signalling pathway.

Emerging Natural-Product-Based Treatments for the Management of Osteoarthritis

Osteoarthritis (OA) is a complex degenerative disease in which joint homeostasis is disrupted, leading to synovial inflammation, cartilage degradation, subchondral bone remodeling, and resulting in pain and joint disability. Yet, the development of new treatment strategies to restore the equilibrium of the osteoarthritic joint remains a challenge. Numerous studies have revealed that dietary components and/or natural products have anti-inflammatory, antioxidant, anti-bone-resorption, and anabolic potential and have received much attention toward the development of new therapeutic strategies for OA treatment. In the present review, we provide an overview of current and emerging natural-product-based research treatments for OA management by drawing attention to experimental, pre-clinical, and clinical models. Herein, we review current and emerging natural-product-based research treatments for OA management.

Silibinin treatment protects human skin cells from UVB injury through upregulation of estrogen receptors

Ultraviolet B (UVB) from the sunlight is a major environmental cause for human skin damages, inducing cell death, inflammation, senescence and even carcinogenesis. The natural flavonoid silibinin, clinically used as liver protectant, has protective effects against UVB-caused skin injury in vivo and in vitro. Silibinin is often classified as a phytoestrogen, because it modulates the activation of estrogen receptors (ERs). However, whether silibinin's estrogenic effect contributes to the skin protection against UVB injury remains to be elucidated. The issue was explored in this study by using the human foreskin dermal fibroblasts (HFF) and human non-malignant immortalized keratinocytes (HaCaT). In HFF, pre-treatment with silibinin rescued UVB-irradiated cells from apoptosis. Interestingly, silibinin increased the whole cellular and nuclear levels of ERα and ERβ in UVB-irradiated cells. Activation of ERs by treatment with estradiol elevated the cell survival and reduced apoptosis in UVB-treated cells. ERα agonist increased cell survival, while its antagonist decreased it. ERβ agonist also increased cell survival, but the antagonist had no effect on cell survival. Transfection of the cells with the small interfering RNAs (si-RNAs) to ERα or ERβ diminished the protective effect of silibinin on UVB-irradiated cells. In UVB-treated HaCaT cells, both ERα and ERβ were increased by silibinin treatment. Inhibition of activation and expression of ERα or ERβ by specific antagonists and si-RNAs, respectively, reduced cell survival in UVB-treated HaCaT cells regardless of silibinin treatment. Taken together, it is summarized that silibinin up-regulates both ERα and ERβ pathways in UVB-treated dermal HFF cells and epidermal HaCaT cells, leading to protection of skin from UVB-damage.

Evaluation of the effect of Silybum marianum extract on menopausal symptoms: A randomized, double-blind placebo-controlled trial

The tendency to use herbs to manage menopausal symptoms has increased in recent years. The purpose of this study was to evaluate the effect of Silybum marianum (L.) compared with placebo in women with hot flashes. Eighty women were randomly allocated into two equal groups (S. marianum extract [400 mg/d] or placebo capsules). Hot flashes frequency and severity were evaluated in 12 weeks with the Greene Climacteric Scale (GCS) and the Hot Flash Related Daily Interference Scale (HFRDIS). The data were analyzed in SPSS software using t-test, Mann-Whitney, chi-square test and repeated measure analysis. Hot flashes frequency and severity decreased from 4.32 ± 0.20/day to 1.31 ± 0.15/day and from 5.25 ± 0.22 to 1.62 ± 0.08, respectively, during the study in test group (p < .001) which were significantly better than effects of placebo in all steps of study (p < .001). Significant decreases in GCS and HFRDIS scores were also detected in S. marianum group compared with placebo after 4, 8 and 12 weeks (p < .001). The results showed that S. marianum can decrease frequency and severity of hot flashes significantly. Considering the safety and high consumption of this herbal medicine worldwide, its use in women with menopausal symptoms can be helpful.

A mechanistic insight of phytoestrogens used for Rheumatoid arthritis: An evidence-based review

Assessment of the potential therapeutic benefits offered by naturally occurring phytoestrogens necessitate inspection of their potency and sites of action in impeding the chronic, systemic, autoimmune, joint destructing disorder Rheumatoid arthritis (RA). Possessing structural and functional similarity with human estrogen, phytoestrogen promisingly replaces the use of hormone therapy in eradicating RA symptoms with their anti-inflammatory, anti-oxidative, anti-proliferative, anti-angiogenesis, immunomodulatory, joint protection properties abolishing the harmful side effects of synthetic drugs. Scientific evidences revealed that use of phytoestrogens from different chemical categories including flavonoids, alkaloids, stilbenoids derived from different plant species manifest beneficial effects on RA through various cellular mechanisms including suppression of pro-inflammatory cytokines in particular tumor necrosis factor (TNF-α), interleukin(IL-6) and nuclear factor kappa B (NF-κB) and destructive metalloproteinases, inhibition of oxidative stress, suppressing inflammatory signalling pathways, attenuating osteoclastogenesis ameliorating cartilage degradation and bone erosion. This review summarizes the evidences of different phytoestrogen treatment and their pharmacological mechanisms in both in vitro and in vivo studies along with discussing clinical evaluations in RA patients showing phytoestrogen as a promising agent for RA therapy. Further investigations and more clinical trials are mandatory to clarify the utility of these plant derived compounds in RA prevention and in managing oestrogen deficient diseases in patients.

Effect of silibinin on ethanol- or acetaldehyde-induced damge of mouse primary hepatocytes in vitro

Silibinin, one of the flavonoids isolated from milk thistle seeds of Silybum marianum, has hepatoprotective properties against toxins in clinical. However, the detailed mechanisms have remained unclear. This study investigates the underlying mechanism of silibinin in the protection against ethanol- or acetaldehyde-induced damage of neonatal mouse primary hepatocytes in vitro. The results show that ethanol inhibited proliferation of hepatocytes in a time (12, 24, 36 h) and dose-dependent (0-800 mM) manner. However, silibinin did not show protective effect on ethanol (500 mM)-induced suppression of hepatocyte proliferation. Acetaldehyde, the toxic metabolite of ethanol, appearing immediately in individuals after drink also inhibited the proliferation of hepatocytes in a dose-dependent (0-12 mM) manner. Surprisingly, silibinin significantly increased the cell viability and reduced the leakage of alanine amino transferase (ALT) and aspartate amino transferase (AST) in acetaldehyde-treated hepatocytes, suggesting that silibinin protected cell injury caused by acetaldehyde treatment. The apoptosis-inducing effect of acetaldehyde was demonstrated by the increased number of cells in sub-G1 phase as well as caspase-3 activation. Further study shows that acetaldehyde induced autophagy in the hepatocytes. The autophagy inhibitors, 3-Methyladenine (3-MA) and chloroquine (CQ), further decreased the viability of cells treated with acetaldehyde, suggesting that autophagy plays a protective role against apoptosis. Consistently, silibinin (20 μM) significantly reduced the activation of caspase 3 or apoptosis and increased the conversion of LC3-I to LC3-II or autophagy. Taken together, it is concluded that silibinin does not repress the ethanol- induced hepatocyte injury, whereas silibinin reduces acetaldehyde-caused hepatocyte injury through down-regulation of apoptosis and up-regulation of autophagy.

Factors and Molecular Mechanisms Influencing the Protein Synthesis, Degradation and Membrane Trafficking of ASIC1a

Acid-sensing ion channels (ASICs) are members of the degenerin/epithelial sodium channel superfamily. They are extracellular pH sensors that are activated by protons. Among all ASICs, ASIC1a is one of the most intensively studied isoforms because of its unique ability to be permeable to Ca²⁺. In addition, it is considered to contribute to various pathophysiological conditions. As a membrane proton receptor, the number of ASIC1a present on the cell surface determines its physiological and pathological functions, and this number partially depends on protein synthesis, degradation, and membrane trafficking processes. Recently, several studies have shown that various factors affect these processes. Therefore, this review elucidated the major factors and underlying molecular mechanisms affecting ASIC1a protein expression and membrane trafficking.

Human pregnancy levels of estrogen and progesterone contribute to humoral immunity by activating TFH /B cell axis

Circulating T_FH (cT_FH ) cells express CXCR5, PD-1, and, when activated, ICOS, and release IL-21. According to the production of IFN-γ, IL-4, and IL-17 and expression of FoxP3, these cells are also classified as cT_FH 1, cT_FH 2, cT_FH 17, and cT_FR cells, respectively. This CD4⁺ T-cell subset is pivotal to efficient humoral immunity, and pregnancy appears to favor IgG production. Here, not only pregnancy amplified the in vivo production of anti-HBsAg IgG in HBV immunized women, but the frequency of cT_FH cells was directly correlated with estradiol levels. In vitro, pregnancy-related dose of 17-β-estradiol (E2) directly increased the percentage of different cT_FH subsets. While E2 and progesterone (P4) increased the proportion of differentiated T_FH cells derived from naïve CD4⁺ T-cells, only E2 amplified the release of IL-21 in those cell cultures. In addition, E2 and P4 increased the proportion of memory B cells and plasma cells, respectively. In SEB-activated B/T_FH cell co-cultures, E2, in the presence of P4, increased the production of total IgG. Finally, among the hormones, P4 was stronger in upregulating the percentage of IL-10⁺ T_FR cells. Collectively, our findings suggested that E2 and P4 cooperate in the humoral immune response by favoring the expansion of different cT_FH and B cell subsets.

Sex steroids and autoimmune rheumatic diseases: state of the art

In autoimmune rheumatic diseases, oestrogens can stimulate certain immune responses (including effects on B cells and innate immunity), but can also have dose-related anti-inflammatory effects on T cells, macrophages and other immune cells. By contrast, androgens and progesterone have predominantly immunosuppressive and anti-inflammatory effects. Hormone replacement therapies and oral contraception (and also pregnancy) enhance or decrease the severity of autoimmune rheumatic diseases at a genetic or epigenetic level. Serum androgen concentrations are often low in men and in women with autoimmune rheumatic diseases, suggesting that androgen-like compounds might be a promising therapeutic approach. However, androgen-to-oestrogen conversion (known as intracrinology) is enhanced in inflamed tissues, such as those present in patients with autoimmune rheumatic diseases. In addition, it is becoming evident that the gut microbiota differs between the sexes (known as the microgenderome) and leads to sex-dependent genetic and epigenetic changes in gastrointestinal inflammation, systemic immunity and, potentially, susceptibility to autoimmune or inflammatory rheumatic diseases. Future clinical research needs to focus on the therapeutic use of androgens and progestins or their downstream signalling cascades and on new oestrogenic compounds such as tissue-selective oestrogen complex to modulate altered immune responses.

Natural flavonoid silibinin promotes the migration and myogenic differentiation of murine C2C12 myoblasts via modulation of ROS generation and down-regulation of estrogen receptor α expression

Skeletal muscle regeneration is a complex process, involving the proliferation, migration, and differentiation of myoblasts. Recent studies suggest that some natural flavanones stimulate myogenesis. However, the effect of plant estrogen, silibinin, on the regulation of myoblast behaviors is unclarified. In this study, we investigated the effects of silibinin on immortalized murine myoblast C2C12 in the aspects of proliferation, migration, differentiation along with underlying mechanisms. The results show that silibinin at concentrations below 50 μM enhanced the migration and differentiation of C2C12 cells, but had no effect on cell proliferation. Silibinin significantly promoted the production of ROS, which appeared to play important roles in the migration and differentiation of the myoblasts. Interestingly, among ROS, the superoxide anion and hydroxyl radical were associated with the migration, whereas hydrogen peroxide contributed to the myogenic differentiation. We used ER agonist and antagonist to explore whether estrogen receptors (ERs), which are affected by silibinin treatment in the silibinin-enhanced C2C12 migration and differentiation. Migration was independent of ERs, whereas the differentiation was associated with decreased ERα activity. In summary, silibinin treatment increases ROS levels, leading to the promotion of migration and myogenic differentiation. Negative regulation ERα of differentiation but not of migration may suggest that ERα represses hydrogen peroxide generation. The effect of silibinin on myoblast migration and differentiation suggests that silibinin may have therapeutic benefits for muscle regeneration.

Phytoestrogens protect joints in collagen induced arthritis by increasing IgG glycosylation and reducing osteoclast activation

Based on previous studies, we know that estrogen can protect the joints from arthritis development by increasing IgG glycosylation and inhibiting osteoclast activation. Phytoestrogens, especially genistein and daidzein, are structurally similar to estradiol that can bind to estrogen receptors (ERs). However, how phytoestrogens affect IgG glycosylation and osteoclast activation in vivo are not investigated so far. In this study, we used 20 mg/kg genistein or daidzein to gavage the female DBA1/J mice in collagen induced arthritis (CIA). We assessed arthritis and bone erosion by clinical scores, histopathology, and micro-CT analysis. Inflammatory cells such as neutrophils, B cells, macrophages and T cells in the peripheral blood were analyzed by flow cytometry. Phagocytic function of peritoneal macrophages was assessed by using FITC-labeled Escherichia coli. New monoclonal antibodies against CII were produced, purified and analyzed. Glycosylation levels of polyclonal and monoclonal IgG were detected by lectin-ELISA. Quantitative PCR was used to analyze the genes related to IgG glycosylation (B4galt1, St6gal1) and osteoclasts (TRAP, NFATC1, c-Fos). Expression of NF-κB and Akt signaling pathways as well as downstream transcription factors NFATc1 and c-Fos was studied by Western blot. Our results show that phytoestrogens protect mice from CIA by increasing IgG glycosylation leading to amelioration of inflammation and inhibiting the NF-κB pathway and NFATc1/c-Fos to decrease the activity of osteoclasts. In conclusion, phytoestrogens can protect bone and joints in CIA mice by increasing IgG glycosylation and inhibiting osteoclast activity.

Estrogen receptor β induces autophagy of osteosarcoma through the mTOR signaling pathway

BACKGROUND

Estrogen receptor beta (ERβ) was considered as a tumor-inhibiting factor in estrogen-sensitive malignant tumors. In this study, we intended to investigate whether ERβ was involved in inducing autophagy in osteosarcoma.

METHODS

This is an experimental study. The associations between ERβ and autophagy were detected in osteosarcoma U2-OS cells which were treated with E2, E2 + 2,3-Bis (4-hydroxyphenyl) propionitrile (DPN, ERβ agonists), E2 + DPN + water, E2 + DPN + 3-Methyladenine (3-MA, autophagy inhibitor), respectively. Cell viability and death were detected using cell counting kit 8 assay and flow cytometry, respectively. In addition, the expression of autophagy marker LC3II/I, sequestosome 1 (P62), mammalian target of rapamycin (mTOR), and phosphorylated-mTOR (p-mTOR) was determined by reverse transcription quantitative polymerase chain reaction (RT-qPCR) and Western blotting.

RESULTS

Cell viability was significantly decreased with DPN treatment, while was reversed with 3-MA treatment. DPN treatment decreased living cells proportion and increased cell apoptosis proportion, while 3-MA treatment reversed those changes. However, there were significant differences between the E2 group and the E2 + DPN + 3-MA group for the living cell proportion and cell apoptosis proportion, suggesting apoptosis and autophagy all were induced. In addition, DPN treatment upregulated the LC3II/I expression level and downregulated P62 and mTOR (mRNA level) and p-mTOR (protein level) expression levels.

CONCLUSION

ERβ inhibited the cell viability and mediated cell death by inducing apoptosis and autophagy in osteosarcoma. ERβ-induced autophagy in osteosarcoma was associated with downregulating the P62 expression level and inhibiting mTOR activation.

Expression of ESR1 and ESR2 oestrogen receptor encoding gene and personality traits - preliminary study

INTRODUCTION

The main objective of the study is to examine the hypothesis claiming a correlation between personality traits measured with the use of the Minnesota Multiphasic Personality Inventory (MMPI-2) personality questionnaire and the expression of the ERα (ESR1) and ERβ (ESR2) encoding gene in patients suffering from depression.

MATERIAL AND METHODS

The experiment was carried out on a group of 44 individuals with depression. The Polish variant of the MMPI-2 was applied with the aim of assessing personality traits. Furthermore, the authors evaluated the expression of the genes encoding the oestrogen receptors (ERα and ERβ) at the mRNA level and protein level in the studied population.

RESULTS

No significant differences in the expression of ERα and ERβ encoding genes were found and confirmed in the patients with the first episode of depression and those suffering from subsequent episodes of the disease. No differences were found between women and men, either. In women a positive relationship was found between the scale of psychopathy (p = 0.04), paranoia (p = 0.01), and mania (p = 0.03) and expression for the ERα encoding gene at the mRNA level. A negative relationship was found between the mania scale and ERβ encoding gene expression at mRNA (p = 0.03) and protein (p = 0.04) levels. In males a positive relationship between anxiety as a personality trait and expression of the ERβ receptor encoding gene at mRNA level (p = 0.03) and protein level (p = 0.03) was found.

CONCLUSIONS

Personality traits may be linked with the expression of genes encoding oestrogen receptors (ERα and ERβ) among patients with depressive disorders.

Estradiol replacement therapy regulates innate immune response in ovariectomized arthritic mice

Neuroendocrine changes are essential factors contributing to the progression and development of rheumatoid arthritis. However, the role of estrogen in the innate immunity during arthritis development is still controversial. Here, we evaluated the effect of estrous cycle, ovariectomy, estradiol replacement therapy and treatment with estrogen receptor (ER)α and ERβ specific agonists on joint edema formation, neutrophil recruitment, and articular levels of cytokines/chemokines in murine zymosan-induced arthritis. Our results showed that articular inflammation of proestus/estrus was similar to metaestus/diestrus animals indicating that the inflammatory response in acute arthritis is not affected by the estrous cycle. However, ovariectomy increased joint swelling, neutrophil migration, and TNF-α level. Treatment for six consecutive days with estradiol cypionate re-established the acute inflammation in ovariectomized arthritic mice to responses similar to those in SHAM-proestrus/estrus or naive mice. Moreover, treatment with propylpyrazoletriol and diarylpropionitrile, two ERα and ERβ selective agonists, respectively, inhibited both edema and neutrophil recruitment. Finally, the non-genomic properties of estradiol were analyzed with an acute treatment with β-estradiol-water soluble, which reduced the edema only. In the present study, estradiol replacement therapy improves the innate immune responses in ovariectomized arthritic mice by activating nuclear estrogen receptors. These results suggest that estradiol can induce a protective anti-inflammatory effect in arthritis during ovaries failure, as observed in the menopause.