Inhibition of glycolysis ameliorate arthritis in adjuvant arthritis rats by inhibiting synoviocyte activation through AMPK/NF-кB pathway

New insights on metabolic reprogramming in macrophage plasticity

Macrophages are the first line of defense in the innate immune system. Macrophages have two subtypes: classically activated macrophages (M1) and alternatively activated macrophages (M2), with different phenotypes and functions. They play a critical role in defending against pathogens and maintaining internal homeostasis. Macrophages have great plasticity in their biological characteristics. Although the regulation of macrophage plasticity has not been fully elucidated, accumulated evidence supports that microenvironmental differences are the root cause for macrophage differentiation into different subtypes. These differences alter macrophage plasticity by modulating key metabolites, activating downstream gene transcription, and influencing phagocytosis, cytokine secretion, and immune regulation. Herein, we systematically summarize metabolic reprogramming, including glucose, lipid, amino acid, ion, vitamin, nucleotide, and butyrate metabolism, as key regulators affecting macrophage polarization, providing new insights for developing targeted drugs that modulate macrophage plasticity.

B cell immunometabolism in health and disease

B cells have crucial roles in the initiation and progression of many pathological conditions, and several therapeutic strategies have targeted the function of these cells. The advent of immunometabolism has provided compelling evidence that the metabolic reprogramming of immune cells can dramatically alter physiopathological immune activities. A better knowledge of the metabolic profiles of B cells can provide valuable means for developing therapies tuning defined cell pathways. Here we review the cellular and molecular mechanisms by which immunometabolism controls the physiology and pathophysiology of B cells and discuss the experimental evidence linking B cell metabolism to health, autoimmunity, and cancer. Considering that several metabolic pathways in B cells are involved differently, or even in opposite ways, in health and disease, we discuss how targeted modulation of B cell immunometabolism could be exploited mechanistically to rebalance abnormal B cell functions that have become altered in disease states.

Energy metabolism in health and diseases

Energy metabolism is indispensable for sustaining physiological functions in living organisms and assumes a pivotal role across physiological and pathological conditions. This review provides an extensive overview of advancements in energy metabolism research, elucidating critical pathways such as glycolysis, oxidative phosphorylation, fatty acid metabolism, and amino acid metabolism, along with their intricate regulatory mechanisms. The homeostatic balance of these processes is crucial; however, in pathological states such as neurodegenerative diseases, autoimmune disorders, and cancer, extensive metabolic reprogramming occurs, resulting in impaired glucose metabolism and mitochondrial dysfunction, which accelerate disease progression. Recent investigations into key regulatory pathways, including mechanistic target of rapamycin, sirtuins, and adenosine monophosphate-activated protein kinase, have considerably deepened our understanding of metabolic dysregulation and opened new avenues for therapeutic innovation. Emerging technologies, such as fluorescent probes, nano-biomaterials, and metabolomic analyses, promise substantial improvements in diagnostic precision. This review critically examines recent advancements and ongoing challenges in metabolism research, emphasizing its potential for precision diagnostics and personalized therapeutic interventions. Future studies should prioritize unraveling the regulatory mechanisms of energy metabolism and the dynamics of intercellular energy interactions. Integrating cutting-edge gene-editing technologies and multi-omics approaches, the development of multi-target pharmaceuticals in synergy with existing therapies such as immunotherapy and dietary interventions could enhance therapeutic efficacy. Personalized metabolic analysis is indispensable for crafting tailored treatment protocols, ultimately providing more accurate medical solutions for patients. This review aims to deepen the understanding and improve the application of energy metabolism to drive innovative diagnostic and therapeutic strategies.

Ginsenoside compound K decreases presentation of citrullinated peptides by regulating autophagy-induced autoantigen activation

OBJECTIVE

Citrullinated vimentin (cVIM) triggers the immune response and is the primary autoantigen of rheumatoid arthritis (RA). Ginsenoside compound K (CK), which exerts significant anti-inflammatory effects, was the objective of this study. We aimed to investigate the role and mechanism of CK in regulating presentation of citrullinated peptides.

METHODS

In RA fibroblast-like synoviocytes (RA-FLS), the expression of autoantigen cVIM, antigen presentation-related molecules, autophagy-related proteins, and autophagic flux were investigated. The effect of CK on the antigen presentation capability of FLS was also examined under conditions of autophagy induction and inhibition. Finally, Wistar rats were immunized with cVIM to evaluate the therapeutic effect of CK in an RA model.

RESULTS

In RA-FLS, CK mitigated the expression of cVIM, autophagy-associated proteins, and antigen presentation-related molecules. This regulatory effect was associated with autophagy. cVIM-immunized rats exhibited more severe arthritis and higher levels of anti-CCP antibodies than those with adjuvant- and vimentin (VIM)-induced arthritis. CK significantly alleviated arthritis inflammation in cVIM-immunized rats.

CONCLUSIONS

CK alleviates cVIM-induced arthritis symptoms, with the regulation of autophagy presenting a key cellular event involved in cVIM generation and RA-FLS antigen-presenting ability.

The role of targeting glucose metabolism in chondrocytes in the pathogenesis and therapeutic mechanisms of osteoarthritis: a narrative review

Osteoarthritis (OA) is a common degenerative joint disease that can affect almost any joint, mainly resulting in joint dysfunction and pain. Worldwide, OA affects more than 240 million people and is one of the leading causes of activity limitation in adults. However, the pathogenesis of OA remains elusive, resulting in the lack of well-established clinical treatment strategies. Recently, energy metabolism alterations have provided new insights into the pathogenesis of OA. Accumulating evidence indicates that glucose metabolism plays a key role in maintaining cartilage homeostasis. Disorders of glucose metabolism can lead to chondrocyte hypertrophy and extracellular matrix degradation, and promote the occurrence and development of OA. This article systematically summarizes the regulatory effects of different enzymes and factors related to glucose metabolism in OA, as well as the mechanism and potential of various substances in the treatment of OA by affecting glucose metabolism. This provides a theoretical basis for a better understanding of the mechanism of OA progression and the development of optimal prevention and treatment strategies.

PHLPP1 inhibits the growth and aerobic glycolysis activity of human ovarian granular cells through inactivating AKT pathway

BACKGROUND

Polycystic ovary syndrome (PCOS) is a disorder characterized by hyperandrogenism, ovulatory dysfunction, and polycystic ovarian morphologic features, and PCOS is associated with infertility. PH domain Leucine-rich repeat Protein Phosphatase 1 (PHLPP1) has been shown to regulate AKT. The aim of present study is to investigate the role of PHLPP1 in PCOS.

METHODS

The expression levels of PHLPP1 in dihydrotestosterone (DHT)-treated human ovarian granular KGN cells were determined by qRT-PCR and Western blot. PHLPP1 was silenced or overexpressed using lentivirus. Cell proliferation was detected by CCK-8. Apoptosis and ROS generation were analyzed by flow cytometry. Glycolysis was analyzed by measuring extracellular acidification rate (ECAR).

RESULTS

DHT treatment suppressed proliferation, promoted apoptosis, enhanced ROS, and inhibited glycolysis in KGN cells. PHLPP1 silencing alleviated the DHT-induced suppression of proliferation and glycolysis, and promotion of apoptosis and ROS in KGN cells. PHLPP1 regulated cell proliferation and glycolysis in human KGN cells via the AKT signaling pathway.

CONCLUSIONS

Our results showed that PHLPP1 mediates the proliferation and aerobic glycolysis activity of human ovarian granular cells through regulating AKT signaling.

PDLIM1 interacts with HK2 to promote gastric cancer progression through enhancing the Warburg effect via Wnt/β-catenin signaling

PDZ and LIM domain protein 1 (PDLIM1) is a cytoskeletal protein and is associated with the malignant pathological features of several tumors. However, the prognostic value of PDLIM1 and the molecular mechanisms by which it is involved in the metabolism and progression in gastric cancer (GC) are still unclear. The GEPIA database was used to predict the expression and prognosis of PDLIM1 in GC. qRT-PCR and western blot assays were applied to detect the mRNA and protein expression in GC tissues and cells. Loss- and gain-of-function experiments were performed to evaluate the biological role of PDLIM1 in GC cells. The Warburg effect was detected by a battery of glycolytic indicators. The interaction of PDLIM1 and hexokinase 2 (HK2) was determined by a co-immunoprecipitation assay. Furthermore, the modulatory effects of PDLIM1 and HK2 on Wnt/β-catenin signaling were assessed. The results showed that PDLIM1 expression was upregulated in GC tissues and cells and was associated with a poor prognosis for GC patients. PDLIM1 inhibition reduced GC cell proliferation, migration and invasion and promoted cell apoptosis. In the glucose deprivation (GLU-D) condition, the PDLIM1 level was reduced and PDLIM1 overexpression led to an increase in glycolysis. Besides, mechanistic investigation showed that PDLIM1 interacted with HK2 to mediate biological behaviors and the glycolysis of GC through Wnt/β-catenin signaling under glucose deprivation. In conclusion, PDLIM1 interacts with HK2 to promote gastric cancer progression by enhancing the Warburg effect via Wnt/β-catenin signaling.

Glucocorticoid receptors involved in ginsenoside compound K ameliorate adjuvant arthritis by inhibiting the glycolysis of fibroblast-like synoviocytes via the NF-κB/HIF-1α pathway

CONTEXT

Ginsenoside metabolite compound K (CK) is an active metabolite produced by ginsenosides in vivo that has an anti-arthritic effect related to the glucocorticoid receptor (GR). However, the potential mechanisms of CK remain unclear.

OBJECTIVE

This study explores the role and potential mechanisms of CK in vivo and in vitro.

MATERIALS AND METHODS

Adjuvant arthritis (AA) model was induced in Sprague-Dawley (SD) rats; the rats were randomly divided into four groups (n = 10): normal, AA, CK (80 mg/kg), and dexamethasone (Dex) group (1 mg/kg). From day 15, rats were treated with CK (once a day, i.g.) and Dex (once every 3 days, i.p.) for 18 days. To further verify the mechanism of CK, fibroblast-like synoviocytes (FLS) were stimulated by tumour necrosis factor α (TNF-α) to establish an inflammatory model in vitro.

RESULTS

CK (80 mg/kg) reduced paw swelling (52%) and arthritis global assessment (31%) compared to that in AA rats. In addition, CK (80 mg/kg) suppressed GLUT1 (38%), HK2 (50%), and PKM2 (56%) levels compared with those in AA FLS. However, the effects of CK (30 μM) on these events were weakened or enhanced after GR knockdown or overexpression in FLS stimulated by TNF-α (30 ng/mL). CK (80 mg/kg) also downregulated the expression of P65 (61%), p-IκB (92%), and HIF-1α (59%).

DISCUSSION AND CONCLUSIONS

The inhibition of CK on glycolysis and the NF-κB/HIF-1α pathway is potentially mediated through activating GR. These findings provide experimental evidence for elucidating the molecular mechanism of CK in treating rheumatoid arthritis (RA).

IL-27 enhances peripheral B cell glycolysis of rheumatoid arthritis patients via activating mTOR signaling

Our previous study found that increased serum IL-27 could promote rheumatoid arthritis (RA) B cell dysfunction via activating mTOR signaling pathway. This study aimed to explore the effects of IL-27 on B cell metabolism and clarify the mechanisms via which IL-27 enhancing glycolysis to induce B cells hyperactivation. Peripheral CD19⁺ B cells were purified from healthy controls (HC) and RA patients and then cultured with or without anti-CD40/CpG and glycolysis inhibitor 2-deoxy-D-glucose (2-DG) or mTOR inhibitor rapamycin. Furthermore, the isolated CD19⁺ B cells were treated by HC serum or RA serum in the presence and absence of recombinant human IL-27 or anti-IL-27 neutralizing antibodies or 2-DG or rapamycin. The B cell glycolysis level, proliferation, differentiation and inflammatory actions were detected by qPCR, flow cytometry or ELISA. We found that the glycolysis in RA B cells was increased significantly compared with HC B cells. Glycolysis inhibition downregulated the proliferation, differentiation, and inflammatory actions of RA B cells. RA serum and IL-27 promoted B cell glycolysis, which could be obviously rescued by anti-IL-27 antibodies or mTOR inhibitor rapamycin. Our results suggest that the enhanced cellular glycolysis of RA B cells induced by IL-27 may contribute to B cells hyperactivation through activating the mTOR signaling pathway.

Glycolytic reprogramming controls periodontitis-associated macrophage pyroptosis via AMPK/SIRT1/NF-κB signaling pathway

Glycolysis has been demonstrated as a crucial metabolic process in bacteria infected diseases via modulating the activity of pyroptosis. Macrophages are the most abundant immune cells that infiltrated in the infected periodontal tissues, which significantly influence the outcome of periodontitis (PD). However, the effect of glycolysis in regulating macrophage pyroptosis during PD development remains unknown. This study aimed to explore the role of glycolysis in PD-associated macrophage pyroptosis and periodontal degeneration. Clinical specimens were used to determine the emergence of macrophage pyroptosis and glycolysis in periodontal tissues by immunohistochemical analysis and western blot. For an in-depth understanding of the regulatory effect of glycolysis in the progression of macrophage pyroptosis associated periodontitis, both in vivo PD model and in vitro PD model were treated with 2-DG (2-Deoxy-d-glucose), a glycolysis inhibitor. The data showed that the blockade of glycolysis could significantly suppress the lipopolysaccharide (LPS) induced macrophage pyroptosis, resulting in an attenuation of the inflammatory response and bone resorption in periodontal lesions. Furthermore, we revealed that the regulatory effect of glycolysis on macrophage pyroptosis can be mediated via AMPK/SIRT1/NF-κB signaling pathway. Our study unveiled that suppressed glycolysis restrains the activity of PD-associated macrophage pyroptosis, osteoclastogenesis, and subsequent periodontal tissue destruction. These findings extend our knowledge of glycolysis in regulating PD-associated macrophage pyroptosis and provide a potential novel target for PD therapy.

Osteoarthritis: pathogenic signaling pathways and therapeutic targets

Osteoarthritis (OA) is a chronic degenerative joint disorder that leads to disability and affects more than 500 million population worldwide. OA was believed to be caused by the wearing and tearing of articular cartilage, but it is now more commonly referred to as a chronic whole-joint disorder that is initiated with biochemical and cellular alterations in the synovial joint tissues, which leads to the histological and structural changes of the joint and ends up with the whole tissue dysfunction. Currently, there is no cure for OA, partly due to a lack of comprehensive understanding of the pathological mechanism of the initiation and progression of the disease. Therefore, a better understanding of pathological signaling pathways and key molecules involved in OA pathogenesis is crucial for therapeutic target design and drug development. In this review, we first summarize the epidemiology of OA, including its prevalence, incidence and burdens, and OA risk factors. We then focus on the roles and regulation of the pathological signaling pathways, such as Wnt/β-catenin, NF-κB, focal adhesion, HIFs, TGFβ/ΒΜP and FGF signaling pathways, and key regulators AMPK, mTOR, and RUNX2 in the onset and development of OA. In addition, the roles of factors associated with OA, including MMPs, ADAMTS/ADAMs, and PRG4, are discussed in detail. Finally, we provide updates on the current clinical therapies and clinical trials of biological treatments and drugs for OA. Research advances in basic knowledge of articular cartilage biology and OA pathogenesis will have a significant impact and translational value in developing OA therapeutic strategies.

CP-25 enhances OAT1-mediated absorption of methotrexate in synoviocytes of collagen-induced arthritis rats

Organic anion transporter 1 (OAT1) plays a major role in mediating the absorption, distribution and excretion of drugs and other xenobiotics in the human body. In this study we explored the OAT1 status in rheumatoid arthritis (RA) patients and arthritic animals and its role in regulating the anti-arthritic activity of methotrexate (MTX). We showed that OAT1 expression was significantly downregulated in synovial tissues from RA patients compared with that in the control patients. In collagen-induced arthritis (CIA) rats, synovial OAT1 expression was significantly decreased compared with the control rats. In synoviocytes isolated from CIA rats, PGE2 (0.003-1.75 μM) dose-dependently downregulated OAT1 expression, resulting in decreased absorption of MTX. Silencing OAT1 in synoviocytes caused a 43.7% reduction in the uptake of MTX. Furthermore, knockdown of OAT1 impaired MTX-induced inhibitory effects on the viability and migration of synoviocytes isolated from CIA rats. Moreover, injection of OAT1-shRNA into articular cavity of CIA rats significantly decreased synovial OAT1 expression and impaired the anti-arthritic action of MTX, while injection of lentivirus containing OAT1 sequences led to the opposite results. Interestingly, we found that paeoniflorin-6'-O-benzene sulfonate (CP-25) upregulated OAT1 expression both in vitro and in vivo and promoted MTX uptake by synoviocytes via regulating OAT1 expression and function. Taken together, OAT1 plays a major role in regulating MTX uptake by synoviocytes and the anti-arthritic activity of MTX. OAT1 is downregulated in RA and CIA rats, which can be improved by CP-25.

Hexokinase inhibitor 2-deoxyglucose coordinates citrullination of vimentin and apoptosis of fibroblast-like synoviocytes by inhibiting HK2 /mTORC1-induced autophagy

High hexokinase 2 (HK2) expression is associated with aberrant activation of fibroblast-like synoviocytes (FLSs) in rheumatoid arthritis (RA). However, the mechanism by which this occurs has not been fully elucidated. To investigate the role of HK2 and its underlying mechanism, adjuvant arthritis (AA) rats were treated with the HK2 inhibitor, 2-deoxyglucose (2-DG). In conjunction with HK2 knockdown experiments in FLSs, we evaluated the effect of HK2 on the citrullination of vimentin (cVIM), autophagy and apoptosis-associated protein expression, including that of cVIM, LC3, p62, Beclin1, Bax, Bcl2, and caspase 3. We further investigated the interaction of HK2 with downstream mTORC1 signaling effectors. Correlation analysis revealed that 2-DG treatment and HK2 knockdown upregulated the expression levels of caspase3, Bax, and p62 and downregulated the expression levels of LC3, Bcl2, and Beclin1, as well as decreasing vimentin citrullination. Furthermore, interactions between HK2 and mTOR decreased, coinciding with mTORC1 pathway activation. These findings suggest that the regulation of apoptosis and cVIM by HK2/mTORC1-dependent autophagy involves the inhibition of aberrant FLSs activation in the rat model of arthritis.

Rheumatoid arthritis and mitochondrial homeostasis: The crossroads of metabolism and immunity

Rheumatoid arthritis is an autoimmune disease characterized by chronic symmetric synovial inflammation and erosive bone destruction. Mitochondria are the main site of cellular energy supply and play a key role in the process of energy metabolism. They possess certain self-regulatory and repair capabilities. Mitochondria maintain relative stability in number, morphology, and spatial structure through biological processes, such as biogenesis, fission, fusion, and autophagy, which are collectively called mitochondrial homeostasis. An imbalance in the mitochondrial homeostatic environment will affect immune cell energy metabolism, synovial cell proliferation, apoptosis, and inflammatory signaling. These biological processes are involved in the onset and development of rheumatoid arthritis. In this review, we found that in rheumatoid arthritis, abnormal mitochondrial homeostasis can mediate various immune cell metabolic disorders, and the reprogramming of immune cell metabolism is closely related to their inflammatory activation. In turn, mitochondrial damage and homeostatic imbalance can lead to mtDNA leakage and increased mtROS production. mtDNA and mtROS are active substances mediating multiple inflammatory pathways. Several rheumatoid arthritis therapeutic agents regulate mitochondrial homeostasis and repair mitochondrial damage. Therefore, modulation of mitochondrial homeostasis would be one of the most attractive targets for the treatment of rheumatoid arthritis.

HK2: a potential regulator of osteoarthritis via glycolytic and non-glycolytic pathways

Osteoarthritis (OA) is an age-related chronic degenerative joint disease where the main characteristics include progressive degeneration of cartilage, varying degrees of synovitis, and periarticular osteogenesis. However, the underlying factors involved in OA pathogenesis remain elusive which has resulted in poor clinical treatment effect. Recently, glucose metabolism changes provide a new perspective on the pathogenesis of OA. Under the stimulation of external environment, the metabolic pathway of chondrocytes tends to change from oxidative phosphorylation (OXPHOS) to aerobic glycolysis. Previous studies have demonstrated that glycolysis of synovial tissue is increased in OA. The hexokinase (HK) is the first rate limiting enzyme in aerobic glycolysis, participating and catalyzing the main pathway of glucose utilization. An isoform of HKs, HK2 is considered to be a key regulator of glucose metabolism, promotes the transformation of glycolysis from OXPHOS to aerobic glycolysis. Moreover, the expression level of HK2 in OA synovial tissue (FLS) was higher than that in control group, which indicated the potential therapeutic effect of HK2 in OA. However, there is no summary to help us understand the potential therapeutic role of glucose metabolism in OA. Therefore, this review focuses on the properties of HK2 and existing research concerning HK2 and OA. We also highlight the potential role and mechanism of HK2 in OA.

Glycolysis in Innate Immune Cells Contributes to Autoimmunity

Autoimmune diseases (AIDs) refer to connective tissue inflammation caused by aberrant autoantibodies resulting from dysfunctional immune surveillance. Most of the current treatments for AIDs use non-selective immunosuppressive agents. Although these therapies successfully control the disease process, patients experience significant side effects, particularly an increased risk of infection. There is a great need to study the pathogenesis of AIDs to facilitate the development of selective inhibitors for inflammatory signaling to overcome the limitations of traditional therapies. Immune cells alter their predominant metabolic profile from mitochondrial respiration to glycolysis in AIDs. This metabolic reprogramming, known to occur in adaptive immune cells, i.e., B and T lymphocytes, is critical to the pathogenesis of connective tissue inflammation. At the cellular level, this metabolic switch involves multiple signaling molecules, including serine-threonine protein kinase, mammalian target of rapamycin, and phosphoinositide 3-kinase. Although glycolysis is less efficient than mitochondrial respiration in terms of ATP production, immune cells can promote disease progression by enhancing glycolysis to satisfy cellular functions. Recent studies have shown that active glycolytic metabolism may also account for the cellular physiology of innate immune cells in AIDs. However, the mechanism by which glycolysis affects innate immunity and participates in the pathogenesis of AIDs remains to be elucidated. Therefore, we reviewed the molecular mechanisms, including key enzymes, signaling pathways, and inflammatory factors, that could explain the relationship between glycolysis and the pro-inflammatory phenotype of innate immune cells such as neutrophils, macrophages, and dendritic cells. Additionally, we summarize the impact of glycolysis on the pathophysiological processes of AIDs, including systemic lupus erythematosus, rheumatoid arthritis, vasculitis, and ankylosing spondylitis, and discuss potential therapeutic targets. The discovery that immune cell metabolism characterized by glycolysis may regulate inflammation broadens the avenues for treating AIDs by modulating immune cell metabolism.

The glycolysis inhibitor 2-deoxyglucose ameliorates adjuvant-induced arthritis by regulating macrophage polarization in an AMPK-dependent manner

Macrophages are highly plastic cells critical for the development of rheumatoid arthritis (RA). Macrophages exhibit a high degree of pro-inflammatory plasticity in RA, accompanied by a metabolic reprogramming from oxidative phosphorylation (OXPHOS) to glycolysis. 2-deoxyglucose (2-DG), a glycolysis inhibitor, has previously been shown to exhibit anti-inflammatory and anti-arthritic properties. However, the specific mechanisms of inflammatory modulation by 2-DG remain unclear. This study used 2-DG to treat rats with adjuvant arthritis (AA) and investigated its specific anti-arthritic mechanisms in the murine-derived macrophage cell line RAW264.7 in vitro. 2-DG reduced the arthritis index as well as alleviated cellular infiltration, synovial hyperplasia, and bone erosion in AA rats. Moreover, 2-DG treatment modulated peritoneal macrophage polarization, increasing levels of the arginase1 (Arg1) and decreasing expression of the inducible nitric oxide synthase (iNOS). 2-DG activated AMP-activated protein kinase (AMPK) via phosphorylation and reduced activation of the nuclear factor κB (NF-κB) in peritoneal macrophages of AA rats. In vitro, we verified that 2-DG promoted macrophage transition from M1 to M2-type by upregulating the expression of p-AMPKα and suppressing NF-κB activation in LPS-stimulated RAW264.7 cells. LPS-induced macrophages exhibited a metabolic shift from glycolysis to OXPHOS following 2-DG treatment, as observed by reduced extracellular acidification rate (ECAR), lactate export, glucose consumption, as well as an elevated oxygen consumption rate (OCR) and intracellular ATP concentration. Importantly, changes in polarization and metabolism in response to 2-DG were dampened after AMPKα knockdown. These findings indicate that the anti-arthritic 2-DG effect is mediated by a modulation of macrophage polarization in an AMPK-dependent manner.

Glycolysis Rate-Limiting Enzymes: Novel Potential Regulators of Rheumatoid Arthritis Pathogenesis

Rheumatoid arthritis (RA) is a classic autoimmune disease characterized by uncontrolled synovial proliferation, pannus formation, cartilage injury, and bone destruction. The specific pathogenesis of RA, a chronic inflammatory disease, remains unclear. However, both key glycolysis rate-limiting enzymes, hexokinase-II (HK-II), phosphofructokinase-1 (PFK-1), and pyruvate kinase M2 (PKM2), as well as indirect rate-limiting enzymes, 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase 3 (PFKFB3), are thought to participate in the pathogenesis of RA. In here, we review the latest literature on the pathogenesis of RA, introduce the pathophysiological characteristics of HK-II, PFK-1/PFKFB3, and PKM2 and their expression characteristics in this autoimmune disease, and systematically assess the association between the glycolytic rate-limiting enzymes and RA from a molecular level. Moreover, we highlight HK-II, PFK-1/PFKFB3, and PKM2 as potential targets for the clinical treatment of RA. There is great potential to develop new anti-rheumatic therapies through safe inhibition or overexpression of glycolysis rate-limiting enzymes.

Transdermal delivery of triptolide-phospholipid complex to treat rheumatoid arthritis

The aim of this study was to develop and evaluate a triptolide phospholipid complex (TPCX) for the treatment of rheumatoid arthritis (RA) by transdermal delivery. TPCX was prepared and characterized by differential scanning calorimetry (DSC), Fourier-transform infrared spectroscopy (FTIR) analysis, transmission electron microscope (TEM), and scanning electron microscope (SEM). The solubility of TPCX was determined. Then, a TPCX cream was prepared to evaluate its percutaneous permeability and the antiarthritis effect. The transdermal permeability was determined using the Franz method, and a microdialysis system was used for skin pharmacokinetic study. A rat model of RA was prepared to evaluate the pharmacological effects. TPCX increased the solubility of triptolide in water, and the percutaneous permeability of TPCX cream was greatly enhanced compared with triptolide cream. The skin pharmacokinetic study indicated that TPCX cream has a longer biological half-life (t_1/2) and mean residence time (MRT), but it has a shorter T_max than that of triptolide cream in vivo. The area under the curve (AUC_0–t)/AUC_0–∞) and the peak concentration (C_max) of TPCX cream were obviously higher than those of triptolide cream. The TPCX-loaded cream alleviated paw swelling and slowed down the progression of arthritis by inhibiting the inflammatory response by down regulating the TNF-α, IL-1β, and IL-6 levels, thus exhibiting excellent antiarthritic effects. In summary, the prepared TPCX effectively increases the hydrophilicity of triptolide, which is good for its percutaneous absorption and enhances its effect on RA rats. TPCX can be a good candidate for the transdermal delivery to treat RA.

Andrographolide, an Anti-Inflammatory Multitarget Drug: All Roads Lead to Cellular Metabolism

Andrographolide is a labdane diterpene and the main active ingredient isolated from the herb Andrographis paniculata. Andrographolide possesses diverse biological effects including anti-inflammatory, antioxidant, and antineoplastic properties. Clinical studies have demonstrated that andrographolide could be useful in therapy for a wide range of diseases such as osteoarthritis, upper respiratory diseases, and multiple sclerosis. Several targets are described for andrographolide, including the interference of transcription factors NF-κB, AP-1, and HIF-1 and signaling pathways such as PI3K/Akt, MAPK, and JAK/STAT. In addition, an increase in the Nrf2 (nuclear factor erythroid 2–related factor 2) signaling pathway also supports its antioxidant and anti-inflammatory properties. However, this scenario could be more complex since recent evidence suggests that andrographolide targets can modulate glucose metabolism. The metabolic effect of andrographolide might be the key to explaining the diverse therapeutic effects described in preclinical and clinical studies. This review discusses some of the most recent evidence about the anti-inflammatory and metabolic effects of andrographolide.