Oridonin suppresses transplant rejection by depleting T cells from the periphery

Oridonin ameliorates renal fibrosis in diabetic nephropathy by inhibiting the Wnt/β-catenin signaling pathway

Diabetic nephropathy (DN) is one of the most serious and frequent complications among diabetes patients and presently constitutes vast the cases of end-stage renal disease worldwide. Tubulointerstitial fibrosis is a crucial factor related to the occurrence and progression of DN. Oridonin (Ori) is a diterpenoid derived from rubescens that has diverse pharmacological properties. Our previous study showed that Ori can protect against DN by decreasing the inflammatory response. However, whether Ori can alleviate renal fibrosis in DN remains unknown. Here, we investigated the mechanism through which Ori affects the Wnt/β-catenin signaling pathway in diabetic rats and human proximal tubular epithelial cells (HK-2) exposed to high glucose (HG) levels. Our results revealed that Ori treatment markedly decreased urinary protein excretion levels, improved renal function and alleviated renal fibrosis in diabetic rats. In vitro, HG treatment increased the migration of HK-2 cells while reducing their viability and proliferation rate, and treatment with Ori reversed these changes. Additionally, the knockdown of β-catenin arrested cell migration and reduced the expression levels of Wnt/β-catenin signaling-related molecules (Wnt4, p-GSK3β and β-catenin) and fibrosis-related molecules (α-smooth muscle actin, collagen I and fibronectin), and Ori treatment exerted an effect similar to that observed after the knockdown of β-catenin. Furthermore, the combination of Ori treatment and β-catenin downregulation exerted more pronounced biological effects than treatment alone. These findings may provide the first line of evidence showing that Ori alleviates fibrosis in DN by inhibiting the Wnt/β-catenin signaling pathway and thereby reveal a novel therapeutic avenue for treating tubulointerstitial fibrosis.

Protein-protein interactions and related inhibitors involved in the NLRP3 inflammasome pathway

NOD-like receptor thermal protein domain-associated protein 3 (NLRP3) receptor serves as the central node of immune sensing in the innate immune system, and plays an important role in the initiation and progression of chronic diseases. Cryo-electron microscopy (cryo-EM) has provided insights into the conformation of various oligomers within the NLRP3 activation pathway, significantly advancing our understanding of the mechanisms underlying NLRP3 inflammasome activation. Despite the extensive network of protein-protein interactions (PPIs) involved in the assembly and activation of NLRP3 inflammasome, the utilization of protein-protein interactions has been relatively overlooked in the development of NLRP3 inhibitors. This review focuses on summarizing PPIs within the NLRP3 inflammasome activation pathway and small molecule inhibitors capable of interfering with PPIs to counteract the NLRP3 overactivation. Small molecule NLRP3 inhibitors have been gained significant attention owing to their remarkable efficacy, excellent safety profiles, and unique mechanisms of action.

Recent advances in oridonin derivatives with anticancer activity

Cancer is a leading cause of mortality responsible for an estimated 10 million deaths worldwide in 2020, and its incidence has been rapidly growing over the last decades. Population growth and aging, as well as high systemic toxicity and chemoresistance associated with conventional anticancer therapies reflect these high levels of incidence and mortality. Thus, efforts have been made to search for novel anticancer drugs with fewer side effects and greater therapeutic effectiveness. Nature continues to be the main source of biologically active lead compounds, and diterpenoids are considered one of the most important families since many have been reported to possess anticancer properties. Oridonin is an ent-kaurane tetracyclic diterpenoid isolated from Rabdosia rubescens and has been a target of extensive research over the last few years. It displays a broad range of biological effects including neuroprotective, anti-inflammatory, and anticancer activity against a variety of tumor cells. Several structural modifications on the oridonin and biological evaluation of its derivatives have been performed, creating a library of compounds with improved pharmacological activities. This mini-review aims to highlight the recent advances in oridonin derivatives as potential anticancer drugs, while succinctly exploring their proposed mechanisms of action. To wind up, future research perspectives in this field are also disclosed.

Oridonin Prolongs the Survival of Mouse Cardiac Allografts by Attenuating the NF-κB/NLRP3 Pathway

Background

Oridonin (Ori), the main bioactive ingredient of the natural anti-inflammatory herb Rabdosia rubescens, could be a covalent inhibitor of the NLRP3 inflammasome. Solid organ transplantation provides a life-saving optional therapy for patients with end-stage organ dysfunction. The long-term survival of solid organ transplantation remains restricted because of the possibility of rejection and the toxicity, infection, cardiovascular disease, and malignancy related to immunosuppressive (IS) drugs. However, the pathogenic mechanisms involved remain unclear. The ideal IS drugs to prevent allograft rejection have not been identified. Here, we investigated whether Ori could prolong the in vivo survival of completely mismatched cardiac allografts.

Methods

The cardiac transplantation models were conducted among three groups of mice from C57BL/6NCrSlc (B6/N) or C3H/HeNSlc (C3H) to C3H: the syngeneic and the allogeneic group, whose recipients were treated with vehicle of Ori, and the Ori treatment group, in which the recipients were transplanted hearts from MHC-I mismatched donors and treated with different dosages of Ori from post-operative day (POD) 0 to 7. Then, we investigated the effect of Ori on bone marrow-derived dendritic cell (BMDC) and allogeneic mixed lymphocyte reaction in vitro.

Results

Ori with 3, 10, and 15 mg/kg Ori could prolong the survival (MST = 22.8, 49.2, and 65.3 days, respectively). We found that infiltrating CD8⁺ T cells and macrophages were decreased, and regulatory T cells (Tregs) were expanded in allografts on POD7. The mRNA level of IL-1β and IFN-γ of allografts was downregulated. Mechanistically, Ori-treated BMDCs suppressed T-cell proliferation and IFN-γ⁺CD4⁺ T-cell differentiation, along with the expansion of Tregs and IL-10⁺CD4⁺ T cells. Ori inhibited NOD, LRR-, and pyrin domain-containing protein 3 (NLRP3) expression; attenuated NF-κB and IκBα phosphorylation in LPS-activated BMDCs; downregulated NLRP3, Caspase-1, IL-1β, IL-18, and IFN-γ; and upregulated IL-10 expression.

Conclusions

Our findings highlight the potential of Ori as a novel and natural IS agent to improve transplant tolerance. Ori could exert IS activity through decreasing IL-1β and IL-18 production and Th1 differentiation and proliferation and expanding Tregs via inhibiting the NF-κB/NLRP3 signaling pathway.

Oridonin: A Review of Its Pharmacology, Pharmacokinetics and Toxicity

Oridonin, as a natural terpenoids found in traditional Chinese herbal medicine Isodon rubescens (Hemsl.) H.Hara, is widely present in numerous Chinese medicine preparations. The purpose of this review focuses on providing the latest and comprehensive information on the pharmacology, pharmacokinetics and toxicity of oridonin, to excavate the therapeutic potential and explore promising ways to balance toxicity and efficacy of this natural compound. Information concerning oridonin was systematically collected from the authoritative internet database of PubMed, Elsevier, Web of Science, Wiley Online Library and Europe PMC applying a combination of keywords involving "pharmacology," "pharmacokinetics," and "toxicology". New evidence shows that oridonin possesses a wide range of pharmacological properties, including anticancer, anti-inflammatory, hepatorenal activities as well as cardioprotective protective activities and so on. Although significant advancement has been witnessed in this field, some basic and intricate issues still exist such as the specific mechanism of oridonin against related diseases not being clear. Moreover, several lines of evidence indicated that oridonin may exhibit adverse effects, even toxicity under specific circumstances, which sparked intense debate and concern about security of oridonin. Based on the current progress, future research directions should emphasize on 1) investigating the interrelationship between concentration and pharmacological effects as well as toxicity, 2) reducing pharmacological toxicity, and 3) modifying the structure of oridonin-one of the pivotal approaches to strengthen pharmacological activity and bioavailability. We hope that this review can provide some inspiration for the research of oridonin in the future.

Phytochemicals: Potential Therapeutic Interventions Against Coronavirus-Associated Lung Injury

Since the outbreak of coronavirus disease 2019 (COVID-19) in December 2019, millions of people have been infected and died worldwide. However, no drug has been approved for the treatment of this disease and its complications, which urges the need for finding novel therapeutic agents to combat. Among the complications due to COVID-19, lung injury has attained special attention. Besides, phytochemicals have shown prominent anti-inflammatory effects and thus possess significant effects in reducing lung injury caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Also, the prevailing evidence reveales the antiviral effects of those phytochemicals, including anti-SARS-CoV activity, which could pave the road in providing suitable lead compounds in the treatment of COVID-19. In the present study, candidate phytochemicals and related mechanisms of action have been shown in the treatment/protection of lung injuries induced by various methods. In terms of pharmacological mechanism, phytochemicals have shown potential inhibitory effects on inflammatory and oxidative pathways/mediators, involved in the pathogenesis of lung injury during COVID-19 infection. Also, a brief overview of phytochemicals with anti-SARS-CoV-2 compounds has been presented.

Protective Effects of Oridonin on Acute Liver Injury via Impeding Posttranslational Modifications of Interleukin-1 Receptor-Associated Kinase 4 (IRAK4) in the Toll-Like Receptor 4 (TLR4) Signaling Pathway

OBJECTIVE

Recent researches have demonstrated that inflammation-related diseases are effectively regulated by posttranslational modifications (PTMs) including phosphorylation and acetylation. Our previous study found a new acetyltransferase inhibitor, oridonin, which had a protective effect on acute liver injury (ALI). In the present study, we further investigated its protective mechanism against D-galactosamine (D-Gal) combined with lipopolysaccharide- (LPS-) induced ALI in mice.

METHODS

Intraperitoneal injections of LPS (40 μg/mouse)/D-Gal (5 mg/mouse) were given to the mice, and the experimental group was pretreated with intraperitoneal injection of oridonin (0.2 mg/mouse). To elucidate the protective mechanism of oridonin, we collected liver specimens and used RNA-sequencing (RNA-Seq) analysis. We focused on the genes that were upregulated by LPS/D-Gal and downregulated after pretreatment with oridonin. The downregulated genes examined by Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis were further verified by real-time polymerase chain reaction (PCR) and western blot.

RESULTS

GO analysis showed that genes that were downregulated after pretreatment with oridonin were extremely concentrated in immune response, chemotaxis, and inflammatory response. Real-time PCR confirmed that the expression of these genes was upregulated by LPS/D-Gal induction and reduced after treatment with oridonin, which was consistent with RNA-Seq results. KEGG pathway analysis showed a significantly enriched downregulated gene that was present in the Toll-like receptor (TLR) 4 signaling cascade. Our results manifested that phosphorylation levels of upstream signaling molecules in the TLR4 signaling cascade, including extracellular signal-regulated kinase (ERK), P38, and IκB, were significantly inhibited by oridonin. Furthermore, LPS/D-Gal stimulation triggered posttranslational modifications of related gene loci in the TLR4 signaling pathway, including phosphorylation of IL-1 receptor-associated kinase 4 (IRAK4 T345/S346) and acetylation of IRAK4 (K34). However, after treatment with oridonin, the modification pattern of IRAK4 expression stimulated by LPS/D-Gal was suggestively attenuated.

CONCLUSION

Our study revealed that the protective effects of oridonin on LPS/D-Gal-induced ALI mediated by inhibition of the PTMs of IRAK4, including phosphorylation of T345/S346 and acetylation of K34.

Oridonin inhibits metastasis of human ovarian cancer cells by suppressing the mTOR pathway

INTRODUCTION

Oridonin, which is isolated from the Chinese herb Rabdosia rubescens, has been reported to exhibit an anti-tumorous effect on different cancers. In this study, we investigated the molecular mechanism by which oridonin suppresses human ovarian cancer.

MATERIAL AND METHODS

The inhibition of oridonin on cell proliferation was assessed by CCK8 assay. Cell cycle and apoptosis were analyzed by flow cytometry, staining with propidium iodide (PI) or annexin-V/PI respectively. The metastasis rate was evaluated using a transwell migration assay. The expression of metastasis-associated genes and mTOR pathway related genes were detected by western blot.

RESULTS

We demonstrated that oridonin suppressed the proliferation and blocked the cell cycle in G1/S phage and induced apoptosis in SKOV3 and A2780 cells (p < 0.01). We further found that the mTOR signaling pathway was suppressed by the treatment with oridonin, and the activation of the mTOR pathway attenuated the anti-tumorous effect of oridonin in human ovarian cancer cells, suggesting that the mTOR pathway was involved in the anti-tumorous process of oridonin. Additionally, the activation of the mTOR pathway by an exogenous activator reduced the expression level of FOXP3 (p < 0.01), thus providing evidence that FOXP3 is a factor that is necessary for the anti-tumorous effect of oridonin, and is negatively regulated by the mTOR pathway.

CONCLUSIONS

These results suggested that oridonin suppressed the mTOR signaling pathway, up-regulated the FOXP3 level, and inhibited metastasis of human ovarian cancer cells.

Effect of dietary oridonin supplementation on growth performance, gut health, and immune response of broilers infected with Salmonella pullorum

Background

The effects of dietary supplementation of oridonin (ORI) on growth performance, cecal microbiota, epithelium development and antioxidant and immune parameters of broilers infected with S. pullorum were studied. A total of 300 1-d-old male chicks were selected and divided into 5 trial groups (6 replicates of 10 chickens): 1) nonchallenge control chicks (CON), 2) chicks treated with Salmonella Challenged Control (SCC), 3) chicks treated with S. pullorum challenge and 50 mg/kg ORI (O1), 4) chicks treated with S. pullorum challenge and 80 mg/kg ORI (O2), and 5) chicks treated with S. pullorum challenge and 100 mg/kg ORI (O3).

Results

The results showed that S. pullorum had no effect on the feed intake (FI), body weight gain (BWG) or feed conversion ratio (FCR) of broilers compared with the values measured for the CON group (P > 0.05). However, compared with the characteristics of CON, S. pullorum showed effects on the counts of Salmonella and Lactobacillus at 7 d and at 14 d (P < 0.05), on jejunal development at 7 d (P < 0.05), and on jejunal immunoglobulin A (IgA) concentration at 7 d (P < 0.05). The addition of 100 mg/kg ORI had the greatest effect on the counts of Lactobacillus and Salmonella in cecal content (P < 0.05), malonaldehyde (MDA) content in the jejunum (P < 0.05), villi height of the small intestine, and IgA concentrations in the jejunum (P < 0.05).

Conclusions

The results suggest that ORI can improve Salmonella-induced immune responses and protect intestinal health, not only through its immune inhibitory properties but also through its multi-protective effects on gut health.

Effects of oridonin on immune cells, Th1/Th2 balance and the expression of BLys in the spleens of broiler chickens challenged with Salmonella pullorum

The aim of this study was to investigate the effects of oridonin (ORI) on the immune cells, Th₁/Th₂ balance and the expression of B lymphocyte stimulator (BLys) in the spleens of broilers infected with Salmonella pullorum. In a completely randomized design, 300 one-day-old AA male broilers were divided to 5 treatments. The groups included a noninfection control (CON) group receiveed a basal diet; a S. pullorum infect control group received the basal diet; and S. pullorum infect group receiveed the basal diet plus 50, 80, and 100 mg/kg ORI, respectively. The results showed that Salmonella challenge increased the relative weights of the spleen, white blood cell counts, lymphocyte and heterophil percentage, H/L ratio, the concentration and mRNA levels of spleen proinflammatory mediators, including tumor necrosis factor-α (TNF-α), interleukin-2 (IL-2), IL-4, IL-6, and IL-10, as well as the anti-inflammatory target Blys (P < .05), and modulated the Th1/Th2 balance (P < .05). ORI pretreatment decreased the relative weight of the spleen and inhibited the release and expression of these proinflammatory mediators and the anti-inflammatory target BLys. The results suggested that ORI supplementation may have immunosuppressive and multiple modulation effects on activated microglia through modulation of the Th1/Th2 balance and BLys expression.

Effects of dietary supplementation with oridonin on the growth performance, relative organ weight, lymphocyte proliferation, and cytokine concentration in broiler chickens

Background

The present study was conducted to investigate the effects of oridonin (ORI) on growth performance, relative organ weight, lymphocyte proliferation, phagocytic function of neutrophils, and cytokine concentration in broiler chickens. A total of 240 one-day-old Arbor Acres male broilers were randomly assigned to four treatments with six replicate pens of 10 broiler chickens per pen. Broiler chickens were fed diets based on four levels of dietary ORI (0, 50, 80 and 100 mg/kg) for a 42-d feeding trial. The experimental diets were fed in three phases: 1 to 14 d, 15 to 28 d and 29 to 42 d.

Results

The results indicated that ORI has no influence on the growth performance (P > 0.05). However, ORI increased the relative weights of spleen and bursa, the number of proliferation peripheral blood T and B lymphocytes, the phagocytic rate of neutrophils, as well as the Interleukin-2 (IL-2), Interleukin-4 (IL-4) and tumor necrosis factor-a (TNF-a) serum concentrations in serum in broilers at days 14, 28 and 42 (P < 0.05).

Conclusions

In conclusion, ORI can enhance immune function and resistance to disease in broiler chickens by stimulating T and B lymphocyte formation, division, and proliferation, as well as the modulation of Th1/Th2 cytokine secretion profiles.

Oridonin Suppresses Proliferation of Human Ovarian Cancer Cells via Blockage of mTOR Signaling

Oridonin, an ent-kaurane diterpenoid compound isolated from the traditional Chinese herb Rabdosia rubescens, has shown various pharmacological and physiological effects such as anti-tumor, anti-bacterial, and anti-inflammatory properties. However, the effect of oridonin on human ovarian cancer cell lines has not been determined. In this study, we demonstrated that oridonin inhibited ovarian cancer cell proliferation, migration and invasion in a dose-dependent manner. Furthermore, we showed oridonin inhibited tumor growth of ovarian cancer cells (SKOV3) in vivo. We then assessed mechanisms and found that oridonin specifically abrogated the phosphorylation/activation of mTOR signaling. In summary, our results indicate that oridonin is a potential inhibitor of ovarian cancer by blocking the mTOR signaling pathway.