Celastrol, a Chinese herbal compound, controls autoimmune inflammation by altering the balance of pathogenic and regulatory T cells in the target organ

Targeting chemokine-receptor mediated molecular signaling by ethnopharmacological approaches

ETHNOPHARMACOLOGICAL RELEVANCE

Infection and inflammation are critical to global human health status and the goal of current pharmacological interventions intends formulating medications/preventives as a measure to deal with this situation. Chemokines and their cognate receptors are major regulatory molecules in many of these ailments. Natural products have been a keen source to the drug development industry, every year contributing significantly to the growing list of FDA approved drugs. A multiverse of natural resource is employed as a part of curative regimen in folk/traditional/ethnomedicine which can be employed to discover, repurpose, and design potent medications for the diseases of clinical concern.

AIM OF THE STUDY

This review aims to systematically document the ethnopharmacologically active agents targeting the infectious-inflammatory diseases through the chemokine-receptor nexus.

MATERIALS AND METHODS

Articles related to chemokine/receptor modulating ethnopharmacological anti-inflammatory, anti-infectious natural sources, bioactive compounds, and formulations have been examined with special emphasis on women related diseases. The available literature has been thoroughly scrutinized for the application of traditional medicines in chemokine associated experimental methods, their regulatory outcomes, and pertinence to women's health wherever applicable. Moreover, the potential traditional regimens under clinical trials have been critically assessed.

RESULTS

A systematic and comprehensive review on the chemokine-receptor targeting ethnopharmaceutics from the available literature has been provided. The article discusses the implication of traditional medicine in the chemokine system dynamics in diverse infectious-inflammatory disorders such as cardiovascular diseases, allergic diseases, inflammatory diseases, neuroinflammation, and cancer. On this note, critical evaluation of the available data surfaced multiple diseases prevalent in women such as osteoporosis, rheumatoid arthritis, breast cancer, cervical cancer and urinary tract infection. Currently there is no available literature highlighting chemokine-receptor targeting using traditional medicinal approach from women's health perspective. Moreover, despite being potent in vitro and in vivo setups there remains a gap in clinical translation of these formulations, which needs to be strategically and scientifically addressed to pave the way for their successful industrial translation.

CONCLUSIONS

The review provides an optimistic global perspective towards the applicability of ethnopharmacology in chemokine-receptor regulated infectious and inflammatory diseases with special emphasis on ailments prevalent in women, consecutively addressing their current status of clinical translation and future directions.

Appraisal of Chitosan-Coated Lipid Nano-Combination with Miltefosine and Albendazole in the Treatment of Murine Trichinellosis: Experimental Study with Evaluation of Immunological and Immunohistochemical Parameters

PURPOSE

Resistance and adverse consequences of albendazole (ABZ) in treating trichinellosis urged demand for secure and effective new drugs. The current study aimed to assess the effect of chitosan-coated lipid nano-combination with albendazole and miltefosine (MFS) in treating experimental murine trichinellosis and evaluating pathological and immunological changes of trichinellosis.

MATERIALS AND METHODS

One hundred twenty Swiss albino mice were divided into six groups. Each group was subdivided into a and b subgroups based on the scarification time, which was 7- and 40-days post-infection (PI), respectively. The treatment efficacy was evaluated using parasitological, histopathological, serological (interleukin (IL)-12 and IL-4 serum levels), immunohistochemical (GATA3, glutathione peroxidase1 (GPX1) and caspase-3), and scanning electron microscopy (SEM) methods.

RESULTS

The most effective drug was nanostructured lipid carriers (NLCs) loaded with ABZ (G5), which showed the most significant reduction in adults and larval count (100% and 92.39%, respectively). The greatest amelioration in histopathological changes was reported in G4 treated with MFS. GATA3 and caspase-3 were significantly reduced in all treated groups. GPX1 was significantly increased in G6 treated with MFS + NLCs. The highest degenerative effects on adults and larvae by SEM were documented in G6.

CONCLUSION

Loading ABZ or MFS on chitosan-coated NLCs enhanced their efficacy against trichinellosis. Although ABZ was better than MFS, their combination should be considered as MFS caused a significant reduction in the intensity of infection. Furthermore, MFS showed anti-inflammatory (↓GATA3) and antiapoptotic effects (↓caspase-3), especially in the muscular phase. Also, when loaded with NLCS, it showed an antioxidant effect (↑GPX1).

Celastrol, which targets IL-2/CD25 binding inhibition, induces T cell-mediated antitumor activity in melanoma

Interleukin-2 (IL-2) induces contrasting immune responses depending on its binding receptor subunit; thus, selective receptor binding is considered a key challenge in cancer therapeutic strategies. In this study, we aimed to investigate the inhibition of IL-2 action and antitumor activity of celastrol (CEL), a compound identified in a screen for IL-2/CD25 binding inhibitors, and to elucidate the underlying role of CEL in immune cells. We found that CEL selectively impairs the binding of IL-2 and CD25 and directly binds to IL-2 but not to CD25. CEL significantly suppressed the proliferation and signaling of IL-2-dependent murine T cells and interfered with IL-2-responsive STAT5 phosphorylation in IL-2 reporter cells and human PBMCs. After confirming the impact of CEL on IL-2, we evaluated its antitumor activity in C57BL/6 mice bearing B16F10 tumors and found that CEL significantly inhibited tumor growth by increasing CD8+ T cells. We also found that CEL did not inhibit tumor growth in T cell-deficient BALB/c nude mice, suggesting that its activity was mediated by the T-cell response. Moreover, combination therapy with low-dose CEL and a TNFR2 antagonist synergistically improved the therapeutic efficacy of the individual monotherapies by increasing the ratio of intratumoral CD8/Treg cells and suppressing Foxp3 expression. These findings suggest that CEL, which inhibits CD25 binding by targeting IL-2, exerts antitumor activity by mediating the T-cell response and could be a promising candidate for combination therapy in cancer immunotherapy against melanoma.

Effect of Salvia miltiorrhiza Bunge extracts on improving the efficacy and reducing the toxicity of Tripterygium wilfordii polyglycosides in the treatment of rheumatoid arthritis

ETHNOPHARMACOLOGICAL RELEVANCE

Tripterygium wilfordii polyglycosides (TWP), extracted from the traditional Chinese herb Tripterygium wilfordii, has been widely used in the treatment of rheumatoid arthritis (RA). However, the toxicity of TWP to a variety of organs such as liver, kidney and testis greatly limits its clinical application. Salvia miltiorrhiza Bunge is often used in the treatment of RA due to its blood circulation promoting, stasis resolving, and anti-inflammatory effects. Salvia miltiorrhiza Bunge has also been reported to possess multiple organ protective effects.

AIM OF THE STUDY

To investigate the influences of two main components of Salviorrhiza miltiorrhiza Bunge, hydrophilic salvianolic acids (SA) and lipophilic tanshinones (Tan), on the efficacy and toxicity of TWP in treating RA and to explore the underlying mechanisms.

MATERIALS AND METHODS

SA and Tan were extracted from Salvia miltiorrhiza Bunge and the extracts were quantitated by HPLC and identified by UPLC-Q/TOF-MS. Then, a collagen-induced arthritis (CIA) rat model was established using bovine type II collagen (CII) and incomplete Freund's adjuvant (IFA). CIA rats were treated with TWP and/or SA/Tan. After 21 days of continuous treatment, arthritis symptoms and organs toxicity were evaluated. Meanwhile, serum metabolomics were investigated by the UPLC-Q/TOF-MS to understand the underlying mechanism.

RESULTS

SA and Tan extracts could significantly alleviate arthritis symptoms in CIA rats and decrease the serum levels of inflammatory factors TNF-α, IL-1β and IL-6 when combined with TWP. Meanwhile, both extracts alleviated injury of liver, kidney and testis caused by TWP, and the hydrophilic extract SA was superior. Moreover, a total of 38 endogenous differential metabolites were identified between the CIA model group and the TWP group, among which 33 metabolites were significantly recovered after the combination of SA or Tan. Metabolic pathway analysis showed that SA and Tan can affect metabolic pathways including linoleic acid metabolism, glycerophospholipid metabolism, sphingolipid metabolism and steroid biosynthesis metabolism pathway.

CONCLUSIONS

Our findings indicated for the first time that two Salviorrhiza miltiorrhiza Bunge extracts could improve the efficacy and reduce the toxicity of TWP in the treatment of RA by adjusting metabolic pathways, and the hydrophilic extract SA was superior.

The roles of lncRNAs in Th17-associated diseases, with special focus on JAK/STAT signaling pathway

One of the most crucial T cell subsets in a variety of autoimmune and chronic inflammatory illnesses is T helper (Th) 17 cells. Th17 cells appear to have an essential role in the clearance of extracellular pathogens during infections. However, Th17 cells are also involved in inflammation and have been implicated in the pathogenesis of several autoimmune diseases and human inflammatory conditions. Due to the involvement of Th17 cells in the onset of Th17-associated diseases, understanding molecular mechanisms of Th17 cell functions may open the door to developing tailored therapies to address these difficult disorders. However, the molecular mechanisms governing Th17 differentiation in various diseases are still not well understood. The JAK/STAT signaling pathway plays a critical role in immune responses and has been linked to various aspects of Th17 cell differentiation and function. In this article, we conducted a comprehensive review of various molecular mechanisms (JAK/STAT, microRNAs, etc.), that can affect the differentiation of Th17 cells in various Th17-associated diseases.

An outlook on the target-based molecular mechanism of phytoconstituents as immunomodulators

The immune system is one of the essential defense mechanisms. Immune system inadequacy increases the risk of infections and cancer diseases, whereas over-activation of the immune system causes allergies or autoimmune disorders. Immunomodulators have been used in the treatment of immune-related diseases. There is growing interest in using herbal medicines as multicomponent agents to modulate the complex immune system in immune-related diseases. Many therapeutic phytochemicals showed immunomodulatory effects by various mechanisms. This mechanism includes stimulation of lymphoid cell, phagocytosis, macrophage, and cellular immune function enhancement. In addition increased antigen-specific immunoglobulin production, total white cell count, and inhibition of TNF-α, IFN-γ, NF-kB, IL-2, IL-6, IL-1β, and other cytokines that influenced the immune system. This review aims to overview, widely investigated plant-derived phytoconstituents by targeting cells to modulate cellular and humoral immunity in in vivo and in vitro. However, further high-quality research is needed to confirm the clinical efficacy of plant-based immunomodulators.

Targeting abnormal lipid metabolism of T cells for systemic lupus erythematosus treatment

Systemic lupus erythematosus (SLE) is an autoimmune disease in which the immune system attacks its own tissues and organs. However, the causes of SLE remain unknown. Dyslipidemia is a common symptom observed in SLE patients and animal models and is closely correlated to disease activity. Lipid metabolic reprogramming has been considered as a hallmark of the dysfunction of T cells in patients with SLE, therefore, manipulating lipid metabolism provides a potential therapeutic target for treating SLE. A better understanding of the underlying mechanisms for the metabolic events of immune cells under pathological conditions is crucial for tuning immunometabolism to manage autoimmune diseases such as SLE. In this review, we aim to summarize the cross-link between lipid metabolism and the function of T cells as well as the underlying mechanisms, and provide light on the novel therapeutic strategies of active compounds from herbals for the treatment of SLE by targeting lipid metabolism in immune cells.

Tripterygium glycosides for safely controlling disease activity in systemic lupus erythematosus: a systematic review with meta-analysis and trial sequential analysis

Background: Tripterygium glycosides have been used to treat systemic lupus erythematosus (SLE) for a long time, showing the effects of immune regulation. We aimed to evaluate the benefits and risks of Tripterygium Glycosides Tablets (TGT) for patients with SLE. Methods: We searched electronic databases and clinical trial registries for relevant randomized controlled trials (RCTs). We identified eligible RCTs and assessed risk of bias. We conducted a meta-analysis to estimate the pooled effects. The Trial Sequential Analysis (TSA) 0.9.5.10 software was used to verify the reliability of the results. Results: Eight RCTs encompassing 538 patients with SLE were included. TGT combined with conventional treatments (CTs) was superior to CTs alone in reducing lupus activity (MD = -1.66, 95% CI = -2.07 to -1.26, p < 0.00001, low-certainty evidence) and improving overall response rate (ORR) (RR = 1.21, 95% CI = 1.11 to 1.32, p < 0.0001, moderate-certainty evidence). The robustness of the results was confirmed by TSA. Regarding safety, there was no statistical difference in the overall incidence of adverse reactions between the two groups. Conclusion: In patients with SLE, TGT might safely reduce disease activity. However, further high-quality studies are needed to firmly establish the clinical efficacy of TGT. Systematic Review Registration: https://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42022300474; Identifier: CRD42022300474.

Seven lower toxicity celastrol derivatives by biotransformation of Pestalotiopsis sp. LGT-1

Biotransformation of toxic components by plant endophytes has become an effective method to reduce the toxicity of target compounds and discover lead compounds. In this context, an endophytic fungus, Pestalotiopsis sp. LGT-1, from Tripterygium wilfordii Hook F. (TwHF), was used to reduce the toxicity of celastrol which is also produced by TwHF and is considered an attractive molecule with a variety of biological activities. Seven celastrol derivatives (1-7) were isolated from the coculture fermentation broth of LGT-1 and celastrol. Their structures were elucidated by spectroscopic data analysis including 1D and 2D NMR, as well as HRESIMS. Their absolute configurations were determined by analysis of NOESY, ECD data and NMR calculations. In cell proliferation experiments, the toxicity of seven compounds was 10.11- to 1.24-fold lower in normal cells than the prototype compound celastrol. These derivatives serve as potential candidates for future pharmaceutical applications.

Celastrol pretreatment attenuates concanavalin A-induced hepatitis in mice by suppressing interleukin-6/STAT3-interleukin-17 signaling

BACKGROUND AND AIM

Celastrol is extracted from Tripterygium wilfordii Hook F. It has been reported to have protective effects against various liver diseases and immune regulation of autoimmune diseases. However, little is known about whether celastrol protects against immune-mediated hepatitis. This study aimed to investigate the effect of celastrol on liver injury induced by concanavalin A (ConA) and the potential mechanisms.

METHODS

Intravenous administration of ConA was applied to induce acute liver injury in mice with or without pretreatment of celastrol. The effects of celastrol on ConA-induced liver injury were further demonstrated by biochemical and histopathological assessments, immunoblotting, and flow cytometry analysis.

RESULTS

Both biochemical and histopathological observations showed that pretreatment of celastrol significantly ameliorated liver injury induced by ConA. Moreover, the hepatocyte apoptosis and inflammatory responses induced by ConA were also improved in celastrol-pretreated mice. Further studies revealed that these improvements were characterized as the celastrol-mediated suppression of total interleukin (IL)-17 from liver mononuclear cells in ConA-treated mice. Flow cytometry analysis suggested that celastrol specifically decreased IL-17 production by CD4⁺ T cells but not by CD8⁺ T cells. Fundamentally, pretreatment with celastrol inhibited both the IL-6 produced by F4/80⁺ macrophages and the IL-6 receptor on Th17 cells in the liver, which further led to the downregulated activation of STAT3, thus accounting for blocked Th17 signaling.

CONCLUSIONS

Celastrol may exhibit immune regulatory effects by regulating IL-6/STAT3-IL-17 signaling in ConA-induced hepatitis, which suggested new potentials for celastrol to be applied in treating immune-mediated liver diseases.

Dissolving microneedle patches-mediated percutaneous delivery of tetramethylpyrazine for rheumatoid arthritis treatment

Recently, transdermal treatment of rheumatoid arthritis (RA) has received increasing attention due to the advantages of improving patient compliance and avoiding gastrointestinal side effects. However, the stratum corneum (SC) barrier limits the transdermal delivery of most substances. Therefore, we constructed tetramethylpyrazine-loaded dissolving microneedle patches (TMP-DMNPs) and investigated its anti-rheumatoid arthritis effect. The cone-shaped dissolving microneedle patch had complete, neatly arranged needles and great mechanical strength. It could effectively penetrate the stratum corneum when applied to the skin. In vitro transdermal experiment showed that DMNPs could significantly promote the transdermal penetration of TMP compared with TMP-cream. The needles were completely dissolved within 18 min and the applied skin recovered completely within 3 h. The excipients and blank DMNP had good safety and biocompatibility to human rheumatoid arthritis fibroblast synovial cells. To compare the therapeutic effects, the animal model was established. The experiments of paw swelling, histopathology and X-ray examination showed that dissolving microneedles significantly alleviated paw condition, reduced the serum concentrations of proinflammatory cytokines, and inhibited synovial tissue damage in AIA rats. These results indicate that the DMNPs we prepared can deliver TMP safely, effectively and conveniently, providing a basis for the percutaneous treatment of RA.

Celastrol attenuates hepatitis C virus translation and inflammatory response in mice by suppressing heat shock protein 90β

Hepatitis C virus (HCV) infection is one of the major factors to trigger a sustained hepatic inflammatory response and hence hepatocellular carcinoma (HCC), but direct-acting-antiviral (DAAs) was not efficient to suppress HCC development. Heat shock protein 90 kDa (HSP90) is highly abundant in different types of cancers, and especially controls protein translation, endoplasmic reticulum stress, and viral replication. In this study we investigated the correlation between the expression levels of HSP90 isoforms and inflammatory response marker NLRP3 in different types of HCC patients as well as the effect of a natural product celastrol in suppression of HCV translation and associated inflammatory response in vivo. We identified that the expression level of HSP90β isoform was correlated with that of NLRP3 in the liver tissues of HCV positive HCC patients (R² = 0.3867, P < 0.0101), but not in hepatitis B virus-associated HCC or cirrhosis patients. We demonstrated that celastrol (3, 10, 30 μM) dose-dependently suppressed the ATPase activity of both HSP90α and HSP90β, while its anti-HCV activity was dependent on the Ala47 residue in the ATPase pocket of HSP90β. Celastrol (200 nM) halted HCV internal ribosomal entry site (IRES)-mediated translation at the initial step by disrupting the association between HSP90β and 4EBP1. The inhibitory activity of celastrol on HCV RNA-dependent RNA polymerase (RdRp)-triggered inflammatory response also depended on the Ala47 residue of HSP90β. Intravenous injection of adenovirus expressing HCV NS5B (pAde-NS5B) in mice induced severe hepatic inflammatory response characterized by significantly increased infiltration of immune cells and hepatic expression level of Nlrp3, which was dose-dependently ameliorated by pretreatment with celastrol (0.2, 0.5 mg/kg, i.p.). This study reveals a fundamental role of HSP90β in governing HCV IRES-mediated translation as well as hepatic inflammation, and celastrol as a novel inhibitor of HCV translation and associated inflammation by specifically targeting HSP90β, which could be developed as a lead for the treatment of HSP90β positive HCV-associated HCC.

Change in Cutibacterium acnes phylotype abundance and improvement of clinical parameters using a new dermocosmetic product containing Myrtus communis and Celastrol enriched plant cell culture extracts in patients with acne vulgaris

BACKGROUND

Acne is a multifactorial chronic inflammatory disease of the pilosebaceous unit, where Cutibacterium acnes plays a main role. Recent papers demonstrated that specific C. acnes phylotypes were correlated with the severity of inflammatory acne and reported a specific loss of C. acnes phylotype diversity in this context.

OBJECTIVES

The aim of this exploratory study was to evaluate the efficacy of a new dermocosmetic product containing Myrtus communis and Celastrol-enriched plant cell culture extracts on C. acnes phylotype abundance and clinical parameters in subjects with mild to moderate acne vulgaris.

METHODS

Cutibacterium acnes phylotype diversity was evaluated by single-locus sequence typing sequencing on the nonlesional areas of the forehead, that is, areas excluding inflammatory lesions (papules and pustules) on day 1 (D1) and after 56 days (D57) of twice daily application of the dermocosmetic product on the whole face. Clinical efficacy on acne was also assessed by acne lesion counting and Global Evaluation Acne (GEA) score on D1 and D57.

RESULTS

Our study confirmed the link between the presence of some C. acnes phylotypes and acne severity. The dermocosmetic cream was linked to a positive impact on C. acnes phylotypes: a significant decrease in pro-pathogen phylotype IC and increase in nonpathogen phylotype IB were observed in the nonlesional areas of acne on D57 compared to D1. In parallel, the clinical results showed a significant decrease in inflammatory and comedonal acne lesions and a significant improvement in the acne severity according to the GEA score.

CONCLUSIONS

This study showed that the application of a new dermocosmetic product containing M. communis and Celastrol-enriched plant cell culture extracts was linked to a change in the C. acnes phylotype abundance and an improvement in acne severity.

Myrtus communis and Celastrol enriched plant cell culture extracts control together the pivotal role of Cutibacterium acnes and inflammatory pathways in acne

INTRODUCTION

Acne is a multifactorial inflammatory disease of the pilosebaceous unit in which Cutibacterium acnes is one of the main triggers. A strong predominance of C. acnes phylotype IA1 is present in acne skin with higher biofilm organization and virulence, promoting local immuno-inflammation, especially the Th17 pathway.

OBJECTIVES

We evaluated the single and combined pharmacological properties of the plant extracts, Myrtus communis (Myrtacine®) and Celastrol enriched plant cell culture (CEE) extracts on the C. acnes/Th17 pathway.

METHODS

The effect of Myrtacine® on the virulence of C. acnes phylotype IA1 was quantified according to the expression of several related genes. The activity of Myrtacine® and CEE on the inflammatory cascade was assessed using monocytes-derived dendritic cells (Mo-DC) stimulated with membranes or biofilms of the C. acnes phylotype IA1. Finally, the effect of CEE on the Th17 pathway was studied using C. acnes stimulated sebocyte 2D cultures and 3D skin tissue models containing preactivated Th17 cells.

RESULTS

Myrtacine® had an anti-virulence effect, evident as a significant and strong inhibition of the expression of several virulence factor genes by 60%-95% compared to untreated controls. Myrtacine® and CEE significantly inhibited proinflammatory cytokine (IL-6, IL-8, IL-12p40 and TNF-α) production by Mo-DC in response to C. acnes phylotype IA1. Interestingly, these two ingredients resulted in synergistic inhibition of most cytokines when used in combination. Finally, we demonstrated an inhibitory effect of CEE, in solution or formulated at 0.3%, specifically on IL-17 release by Th17 lymphocytes in a C. acnes-stimulated sebocyte 2D cultures and by Th17-lymphocytes integrated in a 3D skin models.

CONCLUSIONS

2D and 3D models were developed to represent relevant and specific pathways involved in acne. Myrtacine® and CEE were shown to alter one or more of these pathways, indicating their potential beneficial effects on this disease.

An intra-articular injectable phospholipids-based gel for the treatment of rheumatoid arthritis

Rheumatoid arthritis (RA) is a chronic inflammatory and destructive arthropathy with a high deformity rate. Despite numerous studies and clinical trials, no curative treatment is available for large weight-bearing joints. Intra-articular (IA) injections could deliver high concentrations of drug to the afflicted joint and improve the drug efficacy while reducing systemic toxicity. However, free drugs are rapidly cleared from synovial fluid and do not significantly halt the progression of joint disease. Herein, a phospholipids-based controlled-release gel was prepared for sustained IA delivery of celastrol (CEL) and the therapeutic efficiency was evaluated in a rheumatoid arthritis rabbit model. The CEL-loaded gel (CEL-gel) contained up to 70% phospholipids yet was easy to inject. After injecting into the joint cavity, CEL-gel achieved sol to gel phase transition without special stimuli and gelling agent. In vitro release and in vivo pharmacokinetic studies evidenced the stable and sustained release action of CEL-gel. A single IA injection of CEL-gel could maintain therapeutic efficiency for about 25 d and showed much better anti-arthritic efficacy compared to repeated injections of free drug solution (CEL-sol). Furthermore, the IA injection of CEL-gel greatly reduced the systemic toxicity of CEL. With good biocompatibility and biodegradability, CEL-gel might be a promising IA drug delivery system.

The bone-protective mechanisms of active components from TCM drugs in rheumatoid arthritis treatment

Rheumatoid arthritis (RA) is an autoimmune disease whose hallmarks are synovial inflammation and irreversible bone destruction. Bone resorption resulting from osteoclasts involves the whole immune and bone systems. Breakdown of bone remodeling is attributed to overactive immune cells that produce large quantities of cytokines, upregulated differentiation of osteoclasts with enhanced resorptive activities, suppressed differentiation of osteoblasts, invading fibroblasts and microbiota dysbiosis. Despite the mitigation of inflammation, the existing treatment in Western medicine fails to prevent bone loss during disease progression. Traditional Chinese medicine (TCM) has been used for thousands of years in RA treatment, showing great efficacy in bone preservation. The complex components from the decoctions and prescriptions exhibit various pharmacological activities. This review summarizes the research progress that has been made in terms of the bone-protective effect of some representative compounds from TCM drugs and proposes the substantial mechanisms involved in bone metabolism to provide some clues for future studies. These active components systemically suppress bone destruction via inhibiting joint inflammation, osteoclast differentiation, and fibroblast proliferation. Neutrophil, gut microenvironment and microRNA has been proposed as future focus.

Neuroprotective effects of celastrol on sciatic nerve transection model in male Wistar rats

OBJECTIVES

Celastrol is an herbal compound with neuroprotective properties. Our research aimed to assess the neuroprotective properties of celastrol on sciatic nerve transection in rats.

MATERIALS AND METHODS

The rats' left sciatic nerve was cut and sutured directly. The animals were then given 1 or 2 mg/kg celastrol intraperitoneally for two weeks. The sensory and locomotor behaviors of the animals were then evaluated for 16 weeks. Immunohistochemistry, ELISA, and real-time PCR were also utilized to evaluate macrophage polarization, cytokine secretion, and neurotrophin expression in injured nerves.

RESULTS

Results showed that both doses of celastrol significantly accelerated nerve regeneration and improved sensorimotor functional recovery when compared with controls. Nevertheless, administration of 2 mg/kg of celastrol significantly outperforms treatment with a dose of 1 mg/kg. Celastrol treatment-induced M2 polarization in macrophages decreased proinflammatory cytokines at the injury site. It also increased the expression of BDNF mRNA.

CONCLUSION

These findings suggest that a two-week treatment with celastrol had neuroprotective effects in a rat sciatic nerve transection model, most likely by inducing macrophage M2 polarization and anti-inflammatory effects.

SHP2 inhibition improves celastrol-induced growth suppression of colorectal cancer

This study aimed to explore novel targets for celastrol sensitization in colorectal cancer (CRC) based on differentially regulated signals in response to high- or low-dose celastrol. Targeting signals were investigated using Western blotting or phosphorylated receptor tyrosine kinase (RTK) arrays. Corresponding inhibitors for the signals were individually combined with low-dose celastrol for the assessment of combined anti-CRC effects, based on proliferation, apoptosis, colony assays, and xenograft models. The potential mechanism for the combination of celastrol and SHP2 inhibition was further examined. Low-dose celastrol (&lt;1 µM) did not effectively suppress AKT and ERK signals in CRC cells compared to high-dose celastrol (&gt;1 µM). However, when combined with an AKT or ERK inhibitor, low-dose celastrol could cooperatively suppress CRC proliferation. Furthermore, failed AKT or ERK inhibition by low-dose celastrol may be due to reactivated RTK-SHP2 signaling with negative feedback. The combination of celastrol and the SHP2 inhibitor resulted in greatly reduced AKT and ERK signals, as well as greater inhibition of CRC growth than celastrol alone. Moreover, the mechanism underlying combination suppression was also involved in the activation of immune cell infiltration (mainly for CD8+ cells) in CRC tissues. Failure to inhibit RTK-SHP2-AKT/ERK signaling contributed to the lack of CRC growth suppression by low-dose celastrol. However, the combination of celastrol and the SHP2 inhibitor resulted in synergistic inhibition of CRC growth and provided a promising therapeutic target.

The anti-inflammatory effect of myrrh ethanolic extract in comparison with prednisolone on an autoimmune disease rat model induced by silicate

Autoimmune disease is a complex chronic disease that triggers immune activation against autoantigens resulting in tissue damage. Epidemiological data showed that autoimmune diseases are increasing worldwide over the last decades owing to increased environmental pollution. This study investigates the therapeutic effect of myrrh as a natural medicine compared to prednisolone in the treatment of immune-mediated glomerulonephritis induced by silicate. The autoimmune disease model in rats was induced by injecting 5 mg crystalline sodium silicate suspension subcutaneously once weekly for 20 weeks, and then the rats were treated either with myrrh extract or prednisolone or with both for 6 weeks. Liver and kidney function tests, histopathology, and immunohistochemistry of TNF-α expression in kidney tissue were performed. The creatinine significantly elevated in silica-treated group and decreased in other treated groups. Histopathology of the kidney revealed improvement of glomerular and tubular basement thickness in all treated groups, but the inflammatory cell count slightly decreased in the group treated with myrrh than the other treated groups which showed a marked decrease. TNF-α expression was significantly decreased in all treated groups. Interestingly, the myrrh did not produce hepatic lesions and improve the side effect of prednisolone in the liver when taken in combination. Therefore, myrrh extract possessed anti-inflammatory properties and counteracted the side effect of prednisolone on the liver. Myrrh extract can serve as a conjunctive therapy with prednisolone to treat autoimmune diseases.

Drug Candidates for Autoimmune Diseases

Most of the immunosuppressive drugs used in the clinic to prevent organ rejection or to treat autoimmune disorders were originally isolated from fungi or bacteria. Therefore, in addition to plants, these are valuable sources for identification of new potent drugs. Many side effects of established drugs limit their usage and make the identification of new immunosuppressants necessary. In this review, we present a comprehensive overview of natural products with potent anti-inflammatory activities that have been tested successfully in different models of chronic inflammatory autoimmune diseases. Some of these candidates already have passed first clinical trials. The anti-inflammatory potency of these natural products was often comparable to those of established drugs, and they could be used at least in addition to standard therapy to reduce their dose to minimize unwanted side effects. A frequent mode of action is the inhibition of classical inflammatory signaling pathways, such as NF-κB, in combination with downregulation of oxidative stress. A drawback for the therapeutic use of those natural products is their moderate bioavailability, which can be optimized by chemical modifications and, in addition, further safety studies are necessary. Altogether, very interesting candidate compounds exist which have the potential to serve as starting points for the development of new immunosuppressive drugs.

Beneficial Effects of Celastrol on Immune Balance by Modulating Gut Microbiota in Experimental Ulcerative Colitis Mice

Ulcerative colitis (UC) is a chronic inflammatory bowel disease caused by many factors including colonic inflammation and microbiota dysbiosis. Previous studies have indicated that celastrol (CSR) has strong anti-inflammatory and immune-inhibitory effects. Here, we investigated the effects of CSR on colonic inflammation and mucosal immunity in an experimental colitis model, and addressed the mechanism by which CSR exerts the protective effects. We characterized the therapeutic effects and the potential mechanism of CSR on treating UC using histological staining, intestinal permeability assay, cytokine assay, flow cytometry, fecal microbiota transplantation (FMT), 16S rRNA sequencing, untargeted metabolomics, and cell differentiation. CSR administration significantly ameliorated the dextran sodium sulfate (DSS)-induced colitis in mice, which was evidenced by the recovered body weight and colon length as well as the decreased disease activity index (DAI) score and intestinal permeability. Meanwhile, CSR down-regulated the production of pro-inflammatory cytokines and up-regulated the amount of anti-inflammatory mediators at both mRNA and protein levels, and improved the balances of Treg/Th1 and Treg/Th17 to maintain the colonic immune homeostasis. Notably, all the therapeutic effects were exerted in a gut microbiota-dependent manner. Furthermore, CSR treatment increased the gut microbiota diversity and changed the compositions of the gut microbiota and metabolites, which is probably associated with the gut microbiota-mediated protective effects. In conclusion, this study provides the strong evidence that CSR may be a promising therapeutic drug for UC.

Dietary polyphenols for management of rheumatoid arthritis: Pharmacotherapy and novel delivery systems

Rheumatoid arthritis (RA) is a chronic, complex, systemic autoimmune disease causing chronic inflammation, swelling, and pain. It affects pulmonary and ocular physiology, gastrointestinal disturbance, skeletal disorders, and renal malfunctioning. Although conventional and biological drugs available to treat RA are potent and effective, they lead to life-threatening side effects and patient discomfort. Hence, alternative therapies are explored for their treatment which is safe, effective, and economical. Herbal drugs are widely used as an alternative therapy and some medicinal plants, especially dietary polyphenols proved their efficacy in treating RA. Polyphenols are secondary metabolites of plants possessing several pharmacological actions. They exert anti-inflammatory, immunomodulatory and anti-rheumatoid activity by modulating tumor necrosis factor, mitogen-activated protein kinase, nuclear factor kappa-light-chain-enhancer of activated B cells, and c-Jun N-terminal kinases. Thus, polyphenols could be a promising option for the management of RA. Unfortunately, polyphenols suffer from poor bioavailability due to their physicochemical properties and incorporation into novel delivery systems such as liposomes, nanoparticles, nanoemulsions, micelles improved their oral bioavailability. This review article summarizes dietary polyphenols, their pharmacological actions and novel delivery systems for the treatment of RA. Nevertheless, the commercial translation of polyphenols could be only possible after establishing their safety profile and successful clinical trials.

Anti-inflammatory and anti-arthritic effects of compounds from Buddleja coriacea

Buddleja coriacea (B. coriacea) commonly known as 'Kiswara' is used as infusions for stomach and joint pain. This study aims to evaluate the in vitro and in vivo anti-inflammatory and anti-arthritic activity was evaluated by measuring inflammatory parameters (TNF-α, C-reactive protein and Fibrinogen) in murine models of the aqueous extract and isolated compounds of B. coriacea. A bio-guided phytochemical analysis based on NMR/MS was performed identifying three (1-3) compounds of the aqueous extract. All compounds inhibited the production of TNF-α in RAW 264.7 cell line, with IC₅₀ of 13.44 (1), 1.13 (2) and 0.57 μM (3), respectively. In addition, compounds 2 and 3 decreased the levels of TNF-α, C-reactive protein and fibrinogen at a concentration of 5 mg/kg in murine models. Our research shows that the compounds isolated from B. coriacea have anti-inflammatory and anti-arthritic properties, providing scientific evidence for the traditional use of this plant species.

The mechanism of microglia-mediated immune inflammation in ischemic stroke and the role of natural botanical components in regulating microglia: A review

Ischemic stroke (IS) is one of the most fatal diseases. Neuroimmunity, inflammation, and oxidative stress play important roles in various complex mechanisms of IS. In particular, the early proinflammatory response resulting from the overactivation of resident microglia and the infiltration of circulating monocytes and macrophages in the brain after cerebral ischemia leads to secondary brain injury. Microglia are innate immune cells in the brain that constantly monitor the brain microenvironment under normal conditions. Once ischemia occurs, microglia are activated to produce dual effects of neurotoxicity and neuroprotection, and the balance of the two effects determines the fate of damaged neurons. The activation of microglia is defined as the classical activation (M1 type) or alternative activation (M2 type). M1 type microglia secrete pro-inflammatory cytokines and neurotoxic mediators to exacerbate neuronal damage, while M2 type microglia promote a repairing anti-inflammatory response. Fine regulation of M1/M2 microglial activation to minimize damage and maximize protection has important therapeutic value. This review focuses on the interaction between M1/M2 microglia and other immune cells involved in the regulation of IS phenotypic characteristics, and the mechanism of natural plant components regulating microglia after IS, providing novel candidate drugs for regulating microglial balance and IS drug development.

Immunomodulatory properties of triterpenes

The immune system is one of the main defence mechanisms of the human body. Inadequacy of this system or immunodeficiency results in increased risk of infections and tumours, whereas over-activation of the immune system causes allergic or autoimmune disorders. A well-balanced immune system is important for protection and for alleviation of these diseases. There is a growing interest to maintain a well-balanced immune system, especially after the Covid-19 pandemic. Many biological extracts, as well as natural products, have become popular due to their wide array of immunomodulatory effects and influence on the immune system. Triterpenes, one of the secondary metabolite groups of medicinal plants, exhibit immunomodulatory properties by various mechanisms. Different triterpenes, including components of commonly consumed plants, can promote some protection and alleviation of disease symptoms linked with immune responses and thus enhance overall well-being. This review aims to highlight the efficacy of triterpenes in light of the available literature evidence regarding the immunomodulatory properties of triterpenes. We have reviewed widely investigated immunomodulatory triterpenes; oleanolic acid, glycyrrhizin, glycyrrhetinic acid, pristimerin, ursolic acid, boswellic acid, celastrol, lupeol, betulin, betulinic acid, ganoderic acid, cucumarioside, and astragalosides which have important immunoregulatory properties. In spite of many preclinical and clinical trials were conducted on triterpenes related to their immunoregulatory actions, current studies have several limitations. Therefore, especially more clinical studies with optimal design is essential.

Wilforlide A ameliorates the progression of rheumatoid arthritis by inhibiting M1 macrophage polarization

Rheumatoid arthritis (RA) is an autoimmune disease with increased M1 macrophages. The classical activated M1 macrophages produce various cytokines to control inflammation. Wilforlide A is a natural product that displays anti-inflammatory activities. However, the effect of Wilforlide A on RA progression and the potential mechanisms are unclear. Herein, the collagen-induced arthritis (CIA) mouse was used as an experimental model of RA. The administration of Wilforlide A reduced clinical scores, joint swelling and histological damage in ankle joints of RA mice. The secreted pro-inflammatory factors (MCP1, GM-CSF and M-CSF) and M1 biomarker iNOS in synovium were inhibited by Wilforlide A. In vitro, macrophages deriving from THP-1 cells were stimulated with LPS/IFN-γ to mimic M1 polarization. Similarly, Wilforlide A blocked macrophages polarizing towards M1 subsets. The in vitro results demonstrated that Wilforlide A suppressed LPS/IFN-γ-induced TLR4 upregulation, IκBα degradation and NF-κB p65 activation. In addition, TAK242 (a TLR4 inhibitor) treatment caused a similar inhibitory effect on M1 polarization with Wilforlide A, whereas it was less than the combination of TAK242 and Wilforlide A. Therefore, this work supports that Wilforlide A ameliorates M1 macrophage polarization in RA, which is partially mediated by TLR4/NF-κB signaling pathway inactivation.

Reactive Oxygen Species-Responsive Celastrol-Loaded : Bilirubin Nanoparticles for the Treatment of Rheumatoid Arthritis

Celastrol (CLT) has shown anti-rheumatic activity against rheumatoid arthritis, while its poor water solubility and high organ toxicity restrict its further therapeutic applications. To mitigate these challenges, a reactive oxygen species (ROS)-responsive nanoparticle was developed for celastrol delivery based on the excessive ROS at the pathologic sites, which was synthesized by conjugating bilirubin to a polyethylene glycol (PEG) chain. The PEGylated bilirubin self-assembled into nanoparticle (BRNP) in aqueous solution had a hydrodynamic diameter of around 68.6 nm, and celastrol was loaded into BRNP (CLT/BRNP) with a drug encapsulation efficiency of 72.6% and a loading capacity of 6.6%. In vitro study revealed that CLT/BRNP exhibited the capacity of scavenging intracellular ROS and down-regulating the level of nitric oxide after it was effectively internalized by activated macrophages. Furthermore, in adjuvant-induced arthritis rats, BRNP was accumulated preferentially at inflamed joints, alleviating the joint swelling and bone erosion, which significantly decreased the secretion of pro-inflammatory cytokines to suppress the RA progression. Importantly, CLT/BRNP markedly enhanced its anti-arthritic effect and attenuated the toxic effect compared with free celastrol. Taken together, our results suggested that CLT/BRNP could be used for targeted drug delivery in rheumatoid arthritis.

Antiarthritic activity of OA-DHZ; a gastroprotective NF-κB/MAPK/COX inhibitor

Arthritis, a primary autoimmune disorder having a global incidence of 2.03% person/year, is presently being treated by many commercially available drugs that treat symptomatically or improve the disease's clinical state; however, all the therapies pose varying amount of side effects. Therefore, it has become a fundamental need to search for therapeutics that offer better efficacy and safety profile, and the natural or nature-derived products are known for their outstanding performance in this arena. OA-DHZ, known to possess anti-inflammatory and analgesic properties, when explored for its efficacy against arthritis in adjuvant-induced arthritis (AIA) model, was found to inhibit paw edema by 34% and TNF-α, IL-6, and IL-1β by 67%, 39%, and 45% respectively when compared to diseased control. It was also able to reduce the inflamed spleen size by 45% and successfully normalized biochemical and hematological changes that followed arthritis. In vitro studies revealed that the underlying mechanism for inhibiting arthritis progression might be due to NF-κB /MAPK pathway modulation. OA-DHZ also showed selective inhibition of COX-2 in vitro while showing gastroprotective effects when evaluated for ulcerogenic and antiulcer potential in vivo. In contrast to the results obtained from in vivo experimentation, there is a disparity in the pharmacokinetic profile of OA-DHZ, where it showed low oral exposure and high clearance rate. OA-DHZ being antiarthritic acting via NF-κB /MAPK/ COX inhibition while showing gastroprotective effects, can be a suitable candidate to be in the drug pipeline and further exploration.

Celastrol Niosome Hydrogel Has Anti-Inflammatory Effect on Skin Keratinocytes and Circulation without Systemic Drug Exposure in Psoriasis Mice

Purpose

Psoriasis is an inflammatory skin disease, where keratinocytes play pivotal roles in its pathogenesis. We prepared Celastrol Noisome hydrogel (Cel Nio gel) for the treatment of psoriasis and aimed to study its target site as well as the mechanism.

Methods

Cel Nio was fabricated with thin-film hydration and sonication, then topically administered to imiquimod (IMQ)-induced psoriasis mice. The concentrations of Cel in the skin, blood and lymphatic system were determined using LC-MS. The anti-psoriasis effect of Cel Nio gel was studied, and the levels of inflammatory cytokines in blood were evaluated by flow cytometry. For the in vitro study, the uptake of Nio by HaCaT cells was quantified with flow cytometry, and the anti-inflammatory effect of Cel on HaCaT cells was detected with qPCR. The expressions of inflammatory factors and Ki-67 in skin were observed by immunofluorescence.

Results

Cel Nio possessed a particle size of 133 nm with encapsulation efficacy (EE%) of 83.2%. After topical administration of Cel Nio gel to mice, Cel was mainly accumulated in the skin instead of exposure in blood or lymphatic system, while the levels of inflammatory factors in blood had a significant decline. In addition, the preparation of Nio enhanced the uptake by HaCaT cells, and Cel obviously reduced the mRNA levels of inflammatory cytokines in HaCaT cells. Moreover, Cel Nio gel significantly decreased the expression of inflammatory cytokines and Ki-67 in the skin.

Conclusion

Cel Nio gel achieved the anti-psoriatic effect by inhibiting the inflammation and hyperproliferation of keratinocytes in the skin and further suppressing the systemic inflammation, thus could be a novel topical drug delivery system to treat psoriasis with topical and systemic effects.

Regulation of in vivo delivery of nanomedicines by herbal medicines

Nanomedicines are of increasing scrutiny due to their improved efficacy and/or mitigated side effects. They can be integrated with many other therapeutics to further boost the clinical benefits. Among those, herbal medicines are arousing great interest to be combined with nanomedicines to exert synergistic effects in multifaceted mechanisms. The in vivo performance of nanomedicines which determines the therapeutic efficacy and safety is believed to be heavily influenced by the physio-pathological characters of the body. Activation of multiple immune factors, e.g., complement system, phagocytic cells, lymphocytes, and among many others, can affect the fate of nanomedicines in blood circulation, biodistribution, interaction with single cells and intracellular transport. Immunomodulatory effects and metabolic regulation by herbal medicines have been widely witnessed during the past decades, which alter the physio-pathological conditions and dramatically affect in vivo delivery of nanomedicines. In this review, we summarize recent progress of understanding on the in vivo delivery process of nanomedicines and analyze the major affecting factors that regulate the interaction of nanomedicines with organisms. We discuss the immunomodulatory roles and metabolic regulation by herbal medicines and their effects on in vivo delivery process of nanomedicines, as well as the prospective clinical benefits from the combination of nanomedicines and herbal medicines.

Celastrol targets adenylyl cyclase-associated protein 1 to reduce macrophages-mediated inflammation and ameliorates high fat diet-induced metabolic syndrome in mice

Metabolic syndrome is a clustering of metabolic disorder with unclear molecular mechanism. Increasing studies have found that the pathogenesis and progression of metabolic syndrome are closely related to inflammation. Here, we report celastrol, a traditional Chinese medicine, can improve high fat diet-induced metabolic syndrome through suppressing resistin-induced inflammation. Mechanistically, celastrol binds to adenylyl cyclase associated protein 1 (CAP1) and inhibits the interaction between CAP1 and resistin, which restrains the cyclic adenylate monophosphate (cAMP)-protein kinase A (PKA)-nuclear factor kappa-B (NF-κB) signaling pathway and ameliorates high fat diet-induced murine metabolic syndrome. Knockdown of CAP1 in macrophages abrogated the resistin-mediated inflammatory activity. In contrast, overexpression of CAP1 in macrophages aggravated inflammation. Taken together, our study identifies celastrol, which directly targets CAP1 in macrophages, might be a promising drug candidate for the treatment of inflammatory metabolic diseases, such as metabolic syndrome.

Effective inhibition of Th17/Th22 pathway in 2D and 3D human models of psoriasis by Celastrol enriched plant cell culture extract

BACKGROUND

Psoriasis is an immune-mediated inflammatory disease in which the Th17 pathway is mainly involved. Systemic interventions with biologics that specifically block the Th17 pathway are effective to treat severe psoriasis. However, for efficient topical treatment, small molecules are more suitable than antibodies to penetrate and target epidermal keratinocytes, the key players in psoriasis. Celastrol, a well-described triterpene, is present in low amounts in Tripterygium wilfordii roots. By using plant cell culture (PCC), we were able to boost Celastrol production in bioreactors. Here, we evaluated immune modulator effect of Celastrol enriched extract (CEE) in Th17/Th22 psoriasis induced in 2D and 3D human models in vitro in view of its dermatological usage.

METHODS

Human CD4⁺ T cells (hCD4), Normal Human Epidermal Keratinocytes (NHEK), micro-epidermis and reconstructed human epidermis (RHE) were preincubated with CEE and reference controls. Then, hCD4 were stimulated by anti-[CD3/CD28] while others were stimulated by Th17/22 cytokines cocktails. Psoriasis biomarkers were assessed by ELISA (hCD4 and RHE), by RT-qPCR (NHEK) or by ICH/ELISA (micro-epidermis).

RESULTS

In 2D stimulated models (hCD4 and NHEK), CEE dose dependently inhibited, respectively, the expression of Th17 cytokines and psoriasis induced biomarkers. In 3D models (RHE and micro-epidermis), IL-8 expression was significantly reduced (RHE) and native phenotype was restored by CEE (micro-epidermis).

CONCLUSION

These results clearly showed that Th17/Th22 cytokines, main inflammatory parameters, and psoriasis associated key biomarkers were inhibited by CEE in both 2D and 3D human in vitro models. Therefore, skin homeostasis could be restored by these modulator effects. Moreover, this high added value CEE was obtained by an ecofriendly bioprocess in contrast to traditional roots extracts. This is the first time that a well-defined CEE immune modulator has been proposed for psoriasis adjuvant care to reduce inflammation.

The Role of Natural Products in Rheumatoid Arthritis: Current Knowledge of Basic In Vitro and In Vivo Research

Rheumatoid arthritis (RA) is an autoimmune disorder affecting a vast variety of the population. The onset of RA as well as the development of systematic immunization is affected by both genetic and environmental risk factors. This review aims to point out the role of natural products in the management of RA, focusing on the reports of basic research (in vitro and animal studies) emphasizing the antioxidant and anti-inflammatory properties considered in the field of RA. A systematic screening of the relevant literature was carried out on PubMed, Google Scholar, and Scopus with the following criteria: publication date, 2015-2020; language, English; study design, in vitro or animal models; and the investigation of one or several natural products in the context of RA, including, when available, the molecular mechanisms implicated. A total of 211 papers were initially obtained and screened. In vitro and animal studies referring to 20 natural products and 15 pure compounds were ultimately included in this review. The outcomes of this work provide an overview of the methods employed in basic research over the past five years, with emphasis on the limitations presented, while demonstrating the potential benefits of utilizing natural products in the management of RA as supported by in vitro and animal studies.

Natural Plant Extracts and Compounds for Rheumatoid Arthritis Therapy

Natural plant extracts and compounds (NPECs), which originate from herbs or plants, have been used in the clinical treatment of rheumatoid arthritis (RA) for many years. Over the years, many scientists have carried out a series of studies on the treatment of RA by NPEC. They found a high quantity of active NPECs with broad application prospects. In view of various complex functions of these NPECs, exploring their potential as medicines for RA treatment will be beneficial for RA patients. Thus, to help advance the development of high-quality NPECs for RA, we herein aimed to review the research progress of NPECs in the treatment of RA in recent years. Our findings showed that, from the pharmacological perspective, natural plant extracts or mixed herbal compounds effectively regulate the immune system to alleviate RA by inhibiting pro-inflammatory cytokines. Further, individualized medication can be applied according to each patient's physical condition. However, the pathogenesis of RA and its immune mechanism has not been fully understood and requires further studies.

Celastrol ameliorates Propionibacterium acnes/LPS-induced liver damage and MSU-induced gouty arthritis via inhibiting K63 deubiquitination of NLRP3

BACKGROUND

Celastrol, a pentacyclic triterpenoid quinonemethide isolated from several spp. of Celastraceae family, exhibits anti-inflammatory activities in a variety of diseases including arthritis.

PURPOSE

This study aims to investigate whether the inhibition of NLRP3 inflammasome is engaged in the anti-inflammatory activities of celastrol and delineate the underlying mechanism.

METHODS

The influence of celastrol on NLRP3 inflammasome activation was firstly studied in lipopolysaccharide (LPS)-primed mouse bone marrow-derived macrophages (BMDMs) and phorbol 12-myristate 13-acetate (PMA)-primed THP-1 cells treated with nigericin. Reconstituted inflammasome was also established by co-transfecting NLRP3, ASC, pro-caspase-1 and pro-IL-1β in HEK293T cells. The changes of inflammasome components including NLRP3, ASC, pro-caspase-1/caspase-1 and pro-IL-1β/IL-1β were examined by enzyme-linked immunosorbent assay (ELISA), western blotting and immunofluorescence. Furthermore, Propionibacterium acnes (P. acnes)/LPS-induced liver injury and monosodium urate (MSU)-induced gouty arthritis in mice were employed in vivo to validate the inhibitory effect of celastrol on NLRP3 inflammasome.

RESULTS

Celastrol significantly suppressed the cleavage of pro-caspase-1 and pro-IL-1β, while not affecting the protein expressions of NLRP3, ASC, pro-caspase-1 and pro-IL-1β in THP-1 cells, BMDMs and HEK293T cells. Celastrol suppressed NLRP3 inflammasome activation and alleviated P. acnes/LPS-induced liver damage and MSU-induced gouty arthritis. Mechanism study revealed that celastrol could interdict K63 deubiquitination of NLRP3, which may concern interaction of celastrol and BRCA1/BRCA2-containing complex subunit 3 (BRCC3), and thereby prohibited the formation of NLRP3, ASC and pro-caspase-1 complex to block the generation of mature IL-1β.

CONCLUSION

Celastrol suppresses NLRP3 inflammasome activation in P. acnes/LPS-induced liver damage and MSU-induced gouty arthritis via inhibiting K63 deubiquitination of NLRP3, which presents a novel insight into inhibition of celastrol on NLRP3 inflammasome and provides more evidences for its application in the therapy of inflammation-related diseases.

Tripterygium wilfordii: An inspiring resource for rheumatoid arthritis treatment

Tripterygium wilfordii Hook F (TwHF)-based therapy is among the most efficient and crucial therapeutics for the treatment of rheumatoid arthritis (RA), which indicates that TwHF is a potential source of novel anti-RA drugs. However, accumulating studies have observed that TwHF-based therapy induces multi-organ toxicity, which prevents the wide use of this herb in clinical practice, although several recent studies have attempted to reduce the toxicity of TwHF. Notably, our research group developed a "Clinical Practice Guideline for Tripterygium Glycosides/Tripterygium wilfordii Tablets in the Treatment of Rheumatoid Arthritis" (No. T/CACM 1337-2020) approved by the China Association of Chinese Medicine to standardize the clinical application of TwHF-based therapy and thus avoid adverse effects. Although great strides have been made toward the characterization of TwHF-based therapy and revealing its underlying pharmacological and toxicological mechanisms, several crucial gaps in knowledge remain as potential barriers to enhance its therapeutic effects on the premise of safety assurance. This review offers a global view of TwHF, ranging from its chemical constituents, quality control, clinical observations, and underlying pharmacological mechanisms to toxic manifestations and mechanisms. We focus on the important and emerging aspects of this field and highlight the major challenges and strategies for using novel techniques and approaches to gain new insights into unresolved questions. We hope that this review will improve the understanding of TwHF application and draw increasing interdisciplinary attention from clinicians that practice both Chinese and Western medicine, basic researchers, and computer scientists.

Current advances in the nano-delivery of celastrol for treating inflammation-associated diseases

Inflammation is ubiquitous in the body, and uncontrolled inflammation often contributes to various diseases. Celastrol, a compound isolated from a Chinese medicinal herb, holds great potential in treating multiple inflammation-associated diseases. However, its further clinical use is limited by its poor solubility, bioavailability, and high organ toxicity. With the advancement of nanotechnology, the nano-delivery of celastrol can effectively improve its oral bioavailability, maximize its efficacy and minimize its side effects. Here, we summarize the roles of celastrol in the treatment of various inflammation-associated diseases, with a special emphasis on its role in modulating immune cell signaling or non-immune cell signaling within the inflammatory microenvironment, and we highlight the latest advances in nano-delivery strategies for celastrol to treat diseases associated with inflammation.

Inflammation-Targeted Celastrol Nanodrug Attenuates Collagen-Induced Arthritis through NF-κB and Notch1 Pathways

Rheumatoid arthritis (RA) is a systemic inflammatory disorder which can cause bone and cartilage damage leading to disability, yet the treatment remains unsatisfactory nowadays. Celastrol (Cel) has shown antirheumatic activity against RA. However, the frequent parenteral delivery and poor water solubility of Cel restrict its further therapeutic applications. Here, aiming at effectively overcoming the poor water solubility and short half-life of Cel to boost its beneficial effects for treating RA, we developed a polymeric micelle for Cel delivery based on a reactive oxygen species (ROS) sensitive polymer. Our results demonstrated that Cel may inhibit the repolarization of macrophages toward the pro-inflammatory M1 pheno-type via regulating the NF-κB and Notch1 pathways, which resulted in significantly decreased secretion of multiple pro-inflammatory cytokines to suppress the RA progression. Consequently, the Cel-loaded micelle effectively alleviated the major RA-associated symptoms including articular scores, ankle thickness, synovial inflammation, bone erosion, and cartilage degradation.

Potential Advantages of Bioactive Compounds Extracted From Traditional Chinese Medicine to Inhibit Bone Destructions in Rheumatoid Arthritis

Bone destruction is an important pathological feature of rheumatoid arthritis (RA), which finally leads to the serious decline of life quality in RA patients. Bone metabolism imbalance is the principal factor of bone destruction in RA, which is manifested by excessive osteoclast-mediated bone resorption and inadequate osteoblast-mediated bone formation. Although current drugs alleviate the process of bone destruction to a certain extent, there are still many deficiencies. Recent studies have shown that traditional Chinese medicine (TCM) could effectively suppress bone destruction of RA. Some bioactive compounds from TCM have shown good effect on inhibiting osteoclast differentiation and promoting osteoblast proliferation. This article reviews the research progress of bioactive compounds exacted from TCM in inhibiting bone destruction of RA, so as to provide references for further clinical and scientific research.

Celastrol Efficacy by Oral Administration in the Adjuvant-Induced Arthritis Model

Background: We previously demonstrated that celastrol has significant anti-inflammatory and bone protective effects when administered via the intraperitoneal route. For further preclinical evaluation, an effective oral administration of celastrol is crucial. Here we aimed to study the therapeutic dose range for its oral administration.

Methods: Celastrol (1–25 μg/g/day, N = 5/group) was administrated orally to female adjuvant-induced arthritis (AIA) rats after 8 days of disease induction for a period of 14 days. A group of healthy (N = 8) and arthritic (N = 15) gender- and age-matched Wistar rats was used as controls. During the treatment period, the inflammatory score, ankle perimeter, and body weight were measured. At the end of the treatment, the animals were sacrificed, blood was collected for clinical pathology, necropsy was performed with collection of internal organs for histopathological analysis, and paw samples were used for disease scoring.

Results: Doses higher than 2.5 μg/g/day of celastrol reduced the inflammatory score and ankle swelling, preserved joint structure, halted bone destruction, and diminished the number of synovial CD68+ macrophages. Bone resorption and turnover were also reduced at 5 and 7.5 μg/g/day doses. However, the dose of 7.5 μg/g/day was associated with thymic and liver lesions, and higher doses showed severe toxicity.

Conclusion: Oral administration of celastrol above 2.5 μg/g/day ameliorates arthritis. This data supports and gives relevant information for the development of a preclinical test of celastrol in the setting of a chronic model of arthritis since rheumatoid arthritis is a long-term disease.

Preparation of high drug-loading celastrol nanosuspensions and their anti-breast cancer activities in vitro and in vivo

As one of the main components of Tripterygium wilfordii Hook F, celastrol (CSL) has significant antitumor activity, but its clinical application has been limited by its poor solubility, low oral bioavailability and systemic toxicity. In this study, celastrol nanosuspensions (CSL-NSps) were prepared using an antisolvent precipitation method with poloxamer 188 (P-188) as a stabilizer at a high CSL/P-188 feeding ratio of 8:1. The resultant CSL was spherical in shape with an average particle size of 147.9 nm, a polydispersity index (PDI) of 0.12 and zeta potential of -19.2 mV. The encapsulation efficiency and drug loading content were 98.18% and 86.83%, respectively, and the X-ray diffraction (XRD) pattern showed that CSL existed in an amorphous state in the nanosuspensions. CSL-NSps were quite stable in various physiological media and plasma and were both suitable for oral and intravenous administration. Nanosuspensions greatly enhanced the in vitro dissolution, and the cumulative drug release reached approximately 69.20% within 48 h. In vivo, CSL-NSps (3 mg/kg, i.g.) displayed a significantly enhanced tumor inhibition rate (TIR) in comparison with that of CSL suspension when administered orally (TIR, 50.39%, vs. 41.16%, p < 0.05),  similar to that of PTX injection (8 mg/kg, i.v. TIR, 50.88%). CSL-NSps showed even better therapeutic efficacy than PTX injection (TIR, 64.18%, p < 0.01) when intravenously injected. This has demonstrated that, with the help of nanosuspensions, CSL is likely to be an effective and promising antitumor agent in clinic practice for the treatment of breast cancer.

The Role of Th17/Treg Axis in the Traditional Chinese Medicine Intervention on Immune-Mediated Inflammatory Diseases: A Systematic Review

The Th17/Treg axis plays a crucial role in immune-mediated inflammatory diseases (IMID) and might represent an interesting drug target of treatment strategy for these diseases. Accumulating evidence suggests a role for traditional Chinese medicine (TCM) in the modulation of Th17/Treg axis, but a comprehensive overview which summarizes this field hitherto is lacked. This paper performs a systematic literature review of the regulatory effects of TCM on the imbalance of Th17/Treg axis and its potential mechanisms. In addition, the frequency analysis and network pharmacology for the collected TCM herbs from clinical trial data were performed. The studies reported the changes in the ratio of Th17 and/or Treg cells as well as their transcription factor and related cytokines were included. Frequency analysis of composition of the 39 assessed TCM prescriptions showed that Astragalus membranaceus var.mongholicus (5.20%), Glycyrrhiza uralensis (3.67%), Paeonia obovate (3.06%), Salvia digitaloides (3.06%), and Angelica sinensis (2.75%) were the top five herbal components, which were closely associated to the treatment of IMID. Network pharmacology showed that six target proteins (transforming growth factor (TGF)-beta receptor type-1, TGF-beta receptor type-2, retineic-acid-receptor-related orphan nuclear receptor gamma (ROR-gamma), TGFB2, IL-17 and IL-2, respectively) might be involved in the regulatory effects of TCM on Th17/Treg axis. Moreover, there were nine active ingredients (including Oxymatrine, Baicalin, Triptolide, Paeoniflorin, Sinomenine, Celastrol, Emodin, Diosgenin and Chlorogenic acid) originating from TCM reported to have an immunological regulation effect on the Th17/Treg axis. The highlight of this systematic review is to reveal the pharmacological basis of TCM treating IMID and is helpful for supporting future pharmacologic-driven studies. Further research elucidates the immune-modulating mechanisms on Th17/Treg axis by TCM might provide a broader insight for the treatment of IMID.

Therapeutic targets of thunder god vine (Tripterygium wilfordii hook) in rheumatoid arthritis (Review)

Celastrol and triptolide, chemical compounds isolated from Tripterygium wilfordii hook (also known as thunder god vine), are effective against rheumatoid arthritis (RA). Celastrol targets numerous signaling pathways involving NF‑κB, endoplasmic reticulum Ca2+‑ATPase, myeloid differentiation factor 2, toll‑like receptor 4, pro‑inflammatory chemokines, DNA damage, cell cycle arrest and apoptosis. Triptolide, inhibits NF‑κB, the receptor activator of NF‑κB (RANK)/RANK ligand/osteoprotegerin signaling pathway, cyclooxygenase‑2, matrix metalloproteases and cytokines. The present review examined the chemistry and bioavailability of celastrol and triptolide, and their molecular targets in treating RA. Clinical studies have demonstrated that T. wilfordii has several promising bioactivities, but its multi‑target toxicity has restricted its application. Thus, dosage control and structural modification of T. wilfordii are required to reduce the toxicity. In this review, future directions for research into these promising natural products are discussed.

Enhanced Inflammatory Reaction and Thrombosis in High-Fat Diet-Fed ApoE-/- Mice are Attenuated by Celastrol

OBJECTIVE

High-fat diet (HFD) increases the risk of inflammatory reaction and acute arterial thrombosis. Celastrol has been confirmed to regulate inflammatory cytokine levels in atherosclerotic animal models. However, the anti-thrombotic effects of celastrol have remained to be fully demonstrated. The present study was performed to investigate the beneficial effect of celastrol in HFD-induced inflammatory reaction and thrombosis in apolipoprotein (apo)E^-/- mice.

MATERIALS AND METHODS

Thrombogenic mice model was established using HFD-fed apoE^-/- mice. The levels of mRNA and protein were assayed by RT-qPCR and western blotting, respectively. Immunohistochemistry (IHC) staining was performed to measure the protein expression of matrix metalloproteinase-2 and matrix metalloproteinase-9 in the aortic endothelium of HFD-fed apoE^-/- mice.

RESULTS

The results demonstrated that the effect of HFD on inflammatory cytokines in mice with apoE^-/- background was reversed by celastrol administration, and celastrol treatment inhibited the NOD-like receptor family, pyrin domain containing 3 (NLRP3)/caspase-1/interleukin-1β signaling cascades in peripheral blood mononuclear cells from HFD-fed apoE^-/- mice. In addition, HFD enhanced adenosine diphosphate-induced platelet aggregation in normal C57BL/6 and apoE^-/- mice, while celastrol administration reversed this. Furthermore, celastrol inhibited the pro-thrombotic effects of HFD in apoE^-/- mice, and the underlying mechanism was mediated, at least partially, through the suppression of matrix metalloproteinase-2 and -9 expression.

CONCLUSIONS

Celastrol administration significantly attenuated HFD-induced inflammatory reaction, platelet aggregation and thrombosis in apoE^-/- mice, and celastrol may be used as a drug for the prevention of HFD-induced inflammatory reaction and thrombus.

Celastrol Alleviates Gamma Irradiation-Induced Damage by Modulating Diverse Inflammatory Mediators

The present study aimed to explore the possible radioprotective effects of celastrol and relevant molecular mechanisms in an in vitro cell and in vivo mouse models exposed to gamma radiation. Human keratinocytes (HaCaT) and foreskin fibroblast (BJ) cells were exposed to gamma radiation of 20 Gy, followed by treatment with celastrol for 24 h. Cell viability, reactive oxygen species (ROS), nitric oxide (NO) and glutathione (GSH) production, lipid peroxidation, DNA damage, inflammatory cytokine levels, and NF-κB pathway activation were examined. The survival rate, levels of interleukin-6 (IL-6) and tumor necrosis factor alpha (TNF-α) in blood, and p65 and phospho-p65 expression were also evaluated in mice after exposure to gamma radiation and celastrol treatment. The gamma irradiation of HaCaT cells induced decreased cell viability, but treatment with celastrol significantly blocked this cytotoxicity. Gamma irradiation also increased free radical production (e.g., ROS and NO), decreased the level of GSH, and enhanced oxidative DNA damage and lipid peroxidation in cells, which were effectively reversed by celastrol treatment. Moreover, inflammatory responses induced by gamma irradiation, as demonstrated by increased levels of IL-6, TNF-α, and IL-1β, were also blocked by celastrol. The increased activity of NF-κB DNA binding following gamma radiation was significantly attenuated after celastrol treatment. In the irradiated mice, treatment with celastrol significantly improved overall survival rate, reduced the excessive inflammatory responses, and decreased NF-κB activity. As a NF-κB pathway blocker and antioxidant, celastrol may represent a promising pharmacological agent with protective effects against gamma irradiation-induced injury.

MicroRNA let-7g-5p alleviates murine collagen-induced arthritis by inhibiting Th17 cell differentiation

Rheumatoid arthritis (RA) is a chronic and systemic autoimmune disease with complicated pathogenesis. IL-17-producing T helper cells (Th17) are important players in the RA process. Despite numerous researches have proven that microRNAs (miRNAs) are crucial to regulate autoimmune diseases including RA, the effect of miRNAs on Th17 cell differentiation and function in the RA progress is not clear. Here, our results showed that the expression of miRNA let-7g-5p was substantially lower in RA patients and CIA mice compared with healthy controls, accompanied by the increased Th17 cell population. Furthermore, the inhibition of let-7g-5p on Th17 cell differentiation and function were verified in vitro. Notably, the disease severity in CIA mice was significantly alleviated after the treatment of let-7g-5p mimics. In addition, let-7g-5p mimics treatment markedly down-regulated the frequency of Th17 cells in CIA mice. Taken together, our findings indicate that let-7g-5p can ameliorate CIA through blocking the differentiation of Th17 cells, which may be a novel strategy to treat autoimmune diseases such as RA.

Preventive effects of "ovalbumin-conjugated celastrol-loaded nanomicelles'' in a mouse model of ovalbumin-induced allergic airway inflammation

Allergies affect a significant proportion of the world's population, and existing vaccination strategies to restrict their adverse pathologies often render side-effects. The aim of this study was to design a new vaccine for allergen-specific immunotherapy (SIT), and to investigate its preventive effects during allergic inflammation. We constructed ovalbumin (OVA)-conjugated celastrol-loaded nanomicelles (OVA-NMs-celastrol), wherein celastrol (a bioactive anti-inflammatory compound) was loaded into carboxyl-functioned polymeric nanomicelles using a thin-film hydration method. OVA was used as a model allergen and conjugated on nanomicelles. The OVA-NMs-celastrol obtained were characterized based on particle size, morphology, drug encapsulation efficiency, and drug loading percentage. Further, the preventive effect of OVA-NMs-celastrol was evaluated in a mouse model of allergic asthma. Our results showed that OVA-NMs-celastrol possessed valuable characteristics such as small particle size (50.72 ± 0.98 nm) and spherical-like shape, with celastrol encapsulation efficiency of 99.89 ± 0.85% and a drug loading percentage of 4.76 ± 0.03%. Further, in vivo results showed that treatment with OVA-NMs-celastrol could decrease OVA specific IgE and histamine levels, Th2 cytokine (IL-4, IL-5) levels, and inflammatory cell infiltration in the lung tissues. Moreover, it could enhance the OVA specific IgG1 and IgG2a levels and decrease the IgE / IgG2a ratio. These results demonstrate the successful construction of OVA-NMs-celastrol as a potential vaccine candidate for use in SIT for allergic inflammation.