Celastrol mediates Th17 and Treg cell generation via metabolic signaling

Synthesis and biological evaluation of panaxadiol ester derivatives possessing pyrazole and pyrrole moiety as HIF-1α inibitors

Hypoxia-inducing factor-1α (HIF-1α) is overexpressed in variety of tumor patients and plays an important role in the regulation of hypoxia response in tumor cells. Therefore, its inhibitors have become one of the targets for the treatment of a variety of cancers. Two series of panaxadiol (PD) ester derivatives containing pyrazole (18a-j) and pyrrole (19a-n) moiety were synthesized and their HIF-1α inhibitory activities were evaluated. Among all the target compouds, compounds 18c, 19d, and 19n (IC50 = 8.70-10.44 μM) showed better HIF-1α inhibitory activity than PD (IC50 = 13.35 μM). None of these compounds showed cytotoxicity above 100 μM and inhibited HIF-1α transcription in a dose-dependent manner. These compounds showed good antitumor activity and provide lead compounds for further design and activity study of PD ester derivatives.

Metabolic regulation of the Th17/Treg balance in inflammatory bowel disease

Inflammatory bowel disease (IBD) is a long-lasting and inflammatory autoimmune condition affecting the gastrointestinal tract, impacting millions of individuals globally. The balance between T helper 17 (Th17) cells and regulatory T cells (Tregs) is pivotal in the pathogenesis and progression of IBD. This review summarizes the pivotal role of Th17/Treg balance in maintaining intestinal homeostasis, elucidating how its dysregulation contributes to the development and exacerbation of IBD. It comprehensively synthesizes the current understanding of how dietary factors regulate the metabolic pathways influencing Th17 and Treg cell differentiation and function. Additionally, this review presents evidence from the literature on the potential of dietary regimens to regulate the Th17/Treg balance as a strategy for the management of IBD. By exploring the intersection between diet, metabolic regulation, and Th17/Treg balance, the review reveals innovative therapeutic approaches for IBD treatment, offering a promising perspective for future research and clinical practice.

Downregulation of circular RNA ETS1 promotes SLE activity and inhibits Treg cell differentiation through miR-1205/FoxP3 molecular axis

PURPOSE

This study aimed to explore the mechanism by which systemic lupus erythematosus (SLE) activity is promoted through Treg inhibition from the perspective of ceRNA.

METHODS

qRT-PCR was used to detect the expressions of circETS1, miR-1205, and FoxP3 in clinical SLE patient samples. Overexpression of circETS1and miR-1205, along with knockdown of miR-1205 and FoxP3 were conducted in CD4+ T cells, while the proliferation of helper T cell 17 (Th17) and regulatory T cell (Treg) was detected. Arescue assay was performed to verify the molecular mechanism of circETS1/miR-1205/Foxp3 mRNA axis in regulating CD4+ T cell differentiation. In the in vivo experiment, the expression of miR-1205 in SLE mice was intervened, and renal function, inflammatory factors, and serum complement were measured. Additionally, Treg/Th17 cell ratio was detected by flow cytometry.

RESULTS

In SLE patients, Treg cells were found to decrease, while Th17 cells increased. Transfection with circETS1 overexpression led to CD4+ T cells differentiating into Treg cells, causing an imbalance in the Th17/Treg ratio. Transfection of miR-1205 mimic and si-FoxP3 could reverse the effect of circETS1 overexpression. Moreover, inhibiting the expression of miR-1205 showed therapeutic effects on SLE mice.

CONCLUSION

circETS1 inhibits Treg via the miR-1205/FoxP3 axis, thereby promoting SLE activity, which may become a new target for SLE treatment.

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.

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.

Celastrol functions as an emerging manager of lipid metabolism: Mechanism and therapeutic potential

Lipid metabolism disorders are pivotal in the development of various lipid-related diseases, such as obesity, atherosclerosis, non-alcoholic fatty liver disease, type 2 diabetes, and cancer. Celastrol, a bioactive compound extracted from the Chinese herb Tripterygium wilfordii Hook F, has recently demonstrated potent lipid-regulating abilities and promising therapeutic effects for lipid-related diseases. There is substantial evidence indicating that celastrol can ameliorate lipid metabolism disorders by regulating lipid profiles and related metabolic processes, including lipid synthesis, catabolism, absorption, transport, and peroxidation. Even wild-type mice show augmented lipid metabolism after treatment with celastrol. This review aims to provide an overview of recent advancements in the lipid-regulating properties of celastrol, as well as to elucidate its underlying molecular mechanisms. Besides, potential strategies for targeted drug delivery and combination therapy are proposed to enhance the lipid-regulating effects of celastrol and avoid the limitations of its clinical application.

Targeting the metabolism of tumor-infiltrating regulatory T cells

Although targeting the tumor metabolism is performed in cooperation with immunotherapy in the era of precision oncology, ignorance of immune cells' metabolism has resulted in unstable antitumor responses. Tumor-infiltrating regulatory T cells (TI-Tregs) are unique, overcoming the hypoxic, acidic, and nutrient-deficient tumor microenvironments (TMEs) and maintaining immunosuppressive functions. However, secondary autoimmunity caused by systemic Treg depletion remains the 'Sword of Damocles' for current Treg-targeted therapies. In this opinion piece, we propose that metabolically reprogrammed TI-Tregs might represent an obstacle to cancer therapies. Indeed, metabolism-based Treg-targeted therapy might provide higher selectivity for clearing TI-Tregs than traditional kinase/checkpoint inhibitors and chemokine/chemokine receptor blockade; it might also restore the efficacy of targeting the tumor metabolism and eliminate certain metabolic barriers to immunotherapy.

Autophagy in the pharmacological activities of celastrol (Review)

Celastrol, a natural compound extracted from the traditional Chinese medicinal herb Tripterygium wilfordii Hook F, possesses broad-spectrum pharmacological properties. Autophagy is an evolutionarily conserved catabolic process through which cytoplasmic cargo is delivered to the lysosomes for degradation. Autophagy dysregulation contributes to multiple pathological processes. Therefore, targeting autophagic activity is a promising therapy for various diseases, as well as a drug-development strategy. According to previous studies, autophagy is specifically targeted and may be altered in response to celastrol treatment, highlighting that autophagy modulation is an important mechanism underlying the therapeutic efficacy of celastrol for the treatment of various diseases. The present study summarizes the currently available information regarding the role of autophagy in the effect of celastrol to exert anti-tumor, anti-inflammatory, immunomodulatory, neuroprotective, anti-atherosclerosis, anti-pulmonary fibrosis and anti-macular degeneration activities. The diverse signaling pathways involved are also analyzed to provide insight into the mechanisms of action of celastrol and thereby pave the way for establishing celastrol as an efficacious autophagy modulator in clinical practice.

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 (<1 µM) did not effectively suppress AKT and ERK signals in CRC cells compared to high-dose celastrol (>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.

Chemoproteomic profiling reveals celastrol as a potential modulator of cholesterol signaling

We report a quantitative chemoproteomic approach that utilizes a clickable photoreactive probe for global profiling of celastrol targets, which may significantly improve the current understanding of celastrol's mode of action.

Celastrol Protects against Cerebral Ischemia/Reperfusion Injury in Mice by Inhibiting Glycolysis through Targeting HIF-1α/PDK1 Axis

Cerebral ischemia/reperfusion (I/R) injury is closely related to dysfunctional glucose metabolism. Celastrol is a bioactive compound that has been found to exhibit neuroprotective effects in cerebral ischemia, while whether it can protect against cerebral I/R injury by regulating glycolysis remains unclear. The goal of this study is to investigate the role of celastrol on cerebral I/R injury and its underlying mechanisms in transient middle cerebral artery occlusion (tMCAO) mice. Methods. To observe the protective effect of celastrol and select its optimal dosage for further study, neurological score, TTC staining, and HE staining were used to evaluate neurological function, cerebral infarct volume, and cortical cell damage, respectively. QRT-PCR and Western blot were used to detect the mRNA and protein expression of hypoxia inducible factor-1α (HIF-1α), pyruvate dehydrogenasekinase1 (PDK1), lactate dehydrogenase A (LDHA), glucose transporter1 (GLUT1), and hexokinase2 (HK2), respectively. The lactate production, ATP level, and glucose content were assessed by assay kits. Results. Our results indicated that celastrol dose-dependently improved neurological function and reduced cerebral infarct volume and cortical cell death of tMCAO mice, and its optimal dosage was 4.5 mg/kg. In addition, celastrol significantly blocked I/R-induced increase of LDHA, GLUT1, HK2, and lactate production as well as decrease of ATP level and glucose content. Moreover, celastrol inhibited the I/R-induced upregulation of HIF-1α and PDK1. Overexpression of HIF-1α by DMOG reversed the protective effect of celastrol on cerebral I/R injury and blocked celastrol-induced suppression of glycolysis. Conclusions. Taken together, these results suggested that celastrol protected against cerebral I/R injury through inhibiting glycolysis via the HIF-1α/PDK1 axis.

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.

Tripterygium hypoglaucum (Lévl.) Hutch and Its Main Bioactive Components: Recent Advances in Pharmacological Activity, Pharmacokinetics and Potential Toxicity

Tripterygium hypoglaucum (Lévl.) Hutch (THH) is believed to play an important role in health care and disease treatment according to traditional Chinese medicine. Moreover, it is also the representative of medicine with both significant efficacy and potential toxicity. This characteristic causes THH hard for embracing and fearing. In order to verify its prospect for clinic, a wide variety of studies were carried out in the most recent years. However, there has not been any review about THH yet. Therefore, this review summarized its characteristic of components, pharmacological effect, pharmacokinetics and toxicity to comprehensively shed light on the potential clinical application. More than 120 secondary metabolites including terpenoids, alkaloids, glycosides, sugars, organic acids, oleanolic acid, polysaccharides and other components were found in THH based on phytochemical research. All these components might be the pharmacological bases for immunosuppression, anti-inflammatory and anti-tumour effect. In addition, recent studies found that THH and its bioactive compounds also demonstrated remarkable effect on obesity, insulin resistance, fertility and infection of virus. The main mechanism seemed to be closely related to regulation the balance of immune, inflammation, apoptosis and so on in various disease. Furthermore, the study of pharmacokinetics revealed quick elimination of the main component triptolide. The feature of celastrol was also investigated by several models. Finally, the side effect of THH was thought to be the key for its limitation in clinical application. A series of reports indicated that multiple organs or systems including liver, kidney and genital system were involved in the toxicity. Its potential serious problem in liver was paid specific attention in recent years. In summary, considering the significant effect and potential toxicity of THH as well as its components, the combined medication to inhibit the toxicity, maintain effect might be a promising method for clinical conversion. Modern advanced technology such as structure optimization might be another way to reach the efficacy and safety. Thus, THH is still a crucial plant which remains for further investigation.

Celastrol Regulates the Secretion of Interleukin-17 in Patients with Sympathetic Ophthalmia Through Signal Transducer and Activator of Transcription 3

Purpose: The excessive secretion of interleukin (IL)-17 contributes to the pathological process of sympathetic ophthalmia (SO). Celastrol is a naturally active product and exhibits an immunosuppressive effect. However, whether the supplementation of celastrol relieves SO remains unclear. Methods: The peripheral blood mononuclear cells (PBMCs) were extracted from the venous blood samples of 20 SO patients and 20 healthy controls, followed by stimulating with various concentrations of celastrol. The levels of IL-23 and IL-17 were measured by enzyme-linked immunosorbent assay and real-time polymerase chain reaction assay. The activation of the signal transducer and activator of transcription 3 (STAT3) in PBMCs of SO patients was detected by Western blot. Results: The levels of IL-23 and IL-17 in PBMCs isolated from SO patients were significantly increased compared with those in PBMCs isolated from healthy controls. Celastrol treatment inhibited the production of both IL-23 and IL-17 in PBMCs of SO patients in a dose-dependent manner. In PBMCs isolated from SO patients and healthy controls, the administration of recombinant human IL-23 (rIL-23) enhanced the production of IL-17, which was then suppressed by co-stimulation with celastrol. Also, celastrol treatment reduced rIL-23-induced phosphorylation of STAT3 in PBMCs isolated from SO patients. Conclusions: Celastrol can reduce the production of IL-17 in PBMCs of SO patients. The mechanism may be related to the reduction of IL-23 secretion, which in turn inhibits the phosphorylation of STAT3.

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.

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.

Phloretin Modulates Human Th17/Treg Cell Differentiation In Vitro via AMPK Signaling

Objective

We conducted studies to explore the effect of phloretin on glucose uptake, proliferation, and differentiation of human peripheral blood CD4⁺ T cells and investigated the mechanism of phloretin on inducing Th17/Treg development.

Methods

Naïve CD4⁺ T cells were purified from peripheral blood of healthy volunteers, stimulated with anti-CD3/CD28 antibodies, and polarized in vitro to generate Th17 or Treg cells. Glucose uptake, proliferation, cell cycle, protein expression (phospho-Stat3, phospho-Stat5), and Th17 and Treg cell numbers were analyzed by flow cytometry. AMP-activated protein kinase (AMPK) signaling was analyzed by western blot. Results and Discussion. Phloretin could inhibit the glucose uptake and proliferation of activated CD4⁺ T cells. The proliferation inhibition was due to the G0/G1 phase arrest. Phloretin decreased Th17 cell generation and phospho-Stat3 expression as well as increased Treg cell generation and phospho-Stat5 expression in the process of inducing Th17/Treg differentiation. The phosphorylation level of AMPK was significantly enhanced, while the phosphorylation level of mTOR was significantly decreased in activated CD4⁺ T cells under phloretin treatment. The AMPK signaling inhibitor compound C (Com C) could neutralize the effect of phloretin, while the agonist 5-aminoimidazole-4-carboxamide ribonucleotide (AICAR) could impact the Th17/Treg balance similar to phloretin during Th17/Treg induction.

Conclusion

Our results suggest that phloretin can mediate the Th17/Treg balance by regulating metabolism via the AMPK signal pathway.

Celastrol regulates bone marrow mesenchymal stem cell fate and bone-fat balance in osteoporosis and skeletal aging by inducing PGC-1α signaling

Celastrol has recently been identified as a prospective new treatment for obesity and several metabolic complications. However, the effect of Celastrol in osteoporosis (OP) remains unknown. In this study, we demonstrated that Celastrol promotes osteoblast differentiation and prevents adipocyte differentiation in bone marrow mesenchymal stem cells (BM-MSCs) in vitro. Mechanistically, Celastrol was able to control the differentiation of BM-MSCs by stimulating PGC-1α signaling. Moreover, administration of Celastrol could alleviate bone loss and bone marrow adipose tissue (MAT) accumulation in ovariectomized (OVX) mice and aged mice. Together, these results recommended that Celastrol could regulate BM-MSCs fate and bone-fat balance in OP and skeletal aging by stimulating PGC-1α, which might act as a possible therapeutic target for OP and for the prevention of skeletal aging.

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.

Protective effects of resveratrol and SR1001 on hypoxia-induced pulmonary hypertension in rats

Hypoxic pulmonary hypertension (HPH) is a fatal disease with limited therapeutic strategies. Combination therapy is regarded as the standard of care in PH and becoming widely used in clinical practice. However, many PH patients treated with combinations of available clinical drugs still have a poor prognosis. Therefore, identifying innovative therapeutic strategies is essential for PH. This study is designed to examine the effects of combined prevention with resveratrol and SR1001 on HPH in rats. The effects of combined prevention with resveratrol and SR1001 and each mono-prevention on the development of HPH, Th17 cells differentiation, expression of guanine nucleotide exchange factor-H1 (GEF-H1), Ras homolog gene family member A (RhoA) and Phosphorylated myosin phosphatase target subunit (MYPT1) were examined. HPH and RV hypertrophy occurred in rats exposed to hypoxia. Compared with normoxia group, the hypoxia group showed significantly increased ratio of Th17 cells. After treatment with resveratrol, HPH rats showed an obvious reduction of Th17 cells. SR1001 significantly reduced the increased p-MYPY1, RhoA, and GEF-H1 expression in the hypoxic rats. The mono-prevention with resveratrol or SR1001 significantly inhibited the Th17 cells differentiation, p-STAT3, p-MYPY1, RhoA, and GEF-H1 protein expression, which was further inhibited by their combination prevention. The combination of resveratrol and SR1001 has a synergistic interaction, suggesting that combined use of these pharmacological targets may be an alternative to exert further beneficial effects on HPH.

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.

Metabolic Pathways Involved in Regulatory T Cell Functionality

Regulatory T cells (Treg) are well-known for their immune regulatory potential and are essential for maintaining immune homeostasis. The rationale of Treg-based immunotherapy for treating autoimmunity and transplant rejection is to tip the immune balance of effector T cell-mediated immune activation and Treg-mediated immune inhibition in favor of Treg cells, either through endogenous Treg expansion strategies or adoptive transfer of ex vivo expanded Treg. Compelling evidence indicates that Treg show properties of phenotypic heterogeneity and instability, which has caused considerable debate in the field regarding their correct use. Consequently, for further optimization of Treg-based immunotherapy, it is vital to further our understanding of Treg proliferative, migratory, and suppressive behavior. It is increasingly appreciated that the functional profile of immune cells is highly dependent on their metabolic state. Although the metabolic profiles of effector T cells are progressively understood, little is known on Treg in this respect. The objective of this review is to outline the current knowledge of human Treg metabolic profiles associated with the regulation of Treg functionality. As such information on human Treg is still limited, where information was lacking, we included insightful findings from mouse studies. To assess the available evidence on metabolic pathways involved in Treg functionality, PubMed, and Embase were searched for articles in English indexed before April 28th, 2019 using “regulatory T lymphocyte,” “cell metabolism,” “cell proliferation,” “migration,” “suppressor function,” and related search terms. Removal of duplicates and search of the references was performed manually. We discerned that while glycolysis fuels the biosynthetic and bioenergetic needs necessary for proliferation and migration of human Treg, suppressive capacity is mainly maintained by oxidative metabolism. Based on the knowledge of metabolic differences between Treg and non-Treg cells, we additionally discuss and propose ways of how human Treg metabolism could be exploited for the betterment of tolerance-inducing therapies.

Tripterine up-regulates miR-223 to alleviate lipopolysaccharide-induced damage in murine chondrogenic ATDC5 cells

Tripterine, also known as celastrol, is a main natural ingredient in Tripterygium wilfordii. Tripterine has a variety of pharmacological functions, and the therapeutic potential of tripterine in many kinds of inflammation-linked diseases has been revealed. However, the function of tripterine on osteoarthritis still remains unclear. The objective of this study was to study the function of tripterine (TPR) on lipopolysaccharide (LPS)-injured chondrocyte. ATDC5 cells were treated with tripterine after LPS stimulation and then cell survival, the release of pro-inflammatory cytokines, and the expression of chondrogenic differentiation-associated proteins were assessed by performing CCK-8, flow cytometry, reverse transcription quantitative polymerase chain reaction (RT-qPCR), enzyme-linked immunosorbent assay (ELISA), and Western blot. Moreover, the expression of miR-223 and core factors in PI3K/AKT and nuclear factor kappa B (NF-κB) signaling was tested by RT-qPCR/Western blot. LPS stimulation significantly reduced ATDC5 cells viability, induced apoptosis, and increased the release of interleukin (IL)-6 and tumor necrosis factor (TNF)-α. Tripterine protected ATDC5 cells against LPS-induced chondrocyte loss and the release of IL-6 and TNF-α. miR-223 was down-regulated by LPS, while was up-regulated by tripterine. The protective actions of tripterine were eliminated when miR-223 was silenced. Besides, tripterine inhibited hypertrophic differentiation induced by LPS, and the inhibitory effects of tripterine on hypertrophic differentiation could be abolished when miR-223 was silenced. Furthermore, tripterine activated PI3K/AKT pathway and deactivated NF-κB pathway. And the regulatory effects of tripterine on these two pathways were abolished by miR-223 silence. This study revealed that tripterine protected ATDC5 cells against LPS-induced cell damage possibly via up-regulation of miR-223 and modulation of NF-κB and PI3K/AKT pathways.

Modulation of Lipid Metabolism by Celastrol

Hyperlipidemia, characterized by high serum lipids, is a risk factor for cardiovascular disease. Recent studies have identified an important role for celastrol, a proteasome inhibitor isolated from Tripterygium wilfordii Hook. F., in obesity-related metabolic disorders. However, the exact influences of celastrol on lipid metabolism remain largely unknown. Celastrol inhibited the terminal differentiation of 3T3-L1 adipocytes and decreased the levels of triglycerides in wild-type mice. Lipidomics analysis revealed that celastrol increased the metabolism of lysophosphatidylcholines (LPCs), phosphatidylcholines (PCs), sphingomyelins (SMs), and phosphatidylethanolamines (PEs). Further, celastrol reversed the tyloxapol-induced hyperlipidemia induced associated with increased plasma LPCs, PCs, SMs, and ceramides (CMs). Among these lipids, LPC(16:0), LPC(18:1), PC(22:2/15:0), and SM(d18:1/22:0) were also decreased by celastrol in cultured 3T3-L1 adipocytes, mice, and tyloxapol-treated mice. The mRNAs encoded by hepatic genes associated with lipid synthesis and catabolism, including Lpcat1, Pld1, Smpd3, and Sptc2, were altered in tyloxapol-induced hyperlipidemia, and significantly recovered by celastrol treatment. The effect of celastrol on lipid metabolism was significantly reduced in Fxr-null mice, resulting in decreased Cers6 and Acer2 mRNAs compared to wild-type mice. These results establish that FXR was responsible in part for the effects of celastrol in controlling lipid metabolism and contributing to the recovery of aberrant lipid metabolism in obesity-related metabolic disorders.

Celastrol ameliorates Aspergillus fumigatus keratitis via inhibiting LOX-1

PURPOSE

To investigate the effect of Celastrol (CLT) on Aspergillus fumigatus (A. fumigatus) keratitis.

METHODS

Primary peritoneal macrophages of C57BL/6 mice were pretreated with CLT before A. fumigatus hyphae stimulation. C57BL/6 mice were infected with A. fumigatus. Mice corneas were treated with CLT from 1 day post infection. Clinical score, PCR, ELISA and Western blot were used to test expression of anti-inflammatory mediators, proinflammatory mediators and Lectin-like oxidized low-density lipoprotein receptor 1(LOX-1). The protein levels of p38MAPK after pretreated with CLT in macrophages of C57BL/6 mice challenged with A. fumigatus were tested by Western blot.

RESULTS

C57BL/6 mice treated with CLT from 1 day post infection showed decreased disease, IL-1β, TNF-α, IL-10, TGF-β, MIP-2 and LOX-1 levels. CLT treatment markedly inhibiting mRNA and proteins levels of anti-inflammatory mediators, proinflammatory mediators and LOX-1 in macrophages of C57BL/6 mice compared with control group. CLT pretreatment before A. fumigatus stimulation obviously inhibiting protein levels of p38MAPK versus DMSO pretreated group in macrophages of C57BL/6 mice challenged with A. fumigatus.

CONCLUSION

These data provide evidences that CLT ameliorates A. fumigatus keratitis of C57BL/6 mice via inhibiting LOX-1. CLT pretreatment before A. fumigatus stimulation decreased levels of inflammation in macrophages of C57BL/6 mice, which may be regulated by p-p38MAPK.