The AMPK modulator metformin as adjunct to methotrexate in patients with rheumatoid arthritis: A proof-of-concept, randomized, double-blind, placebo-controlled trial

The PIKASO trial (Preventing Injured Knees from Osteoarthritis: Severity Outcomes): Rationale and design features for a randomized controlled trial

Objective

Given the high burden and increasing prevalence of post-traumatic osteoarthritis (PTOA), identifying clinically beneficial strategies to prevent or delay its onset could improve the quality of life of those at high risk of developing the disease.

Methods

Preventing Injured Knees from OsteoArthritis: Severity Outcomes (PIKASO) is a multicenter blinded, parallel, two-arm randomized controlled trial of 512 individuals aged 18-45 years undergoing anterior cruciate ligament reconstruction (ACLR). This study is designed to evaluate the efficacy of a 12-month intervention of oral metformin vs. placebo in decreasing the rate of structural knee changes and pain. Participants will be asked to take up to 1500 ​mg/day of either metformin or placebo as tolerated. The primary outcomes are Knee injury and Osteoarthritis Outcome Score (KOOS) Pain subscale scores averaged between 12 and 24 months after randomization, and MRI derived cartilage structural change at 24 months. The trial will be deemed successful if at least one of the two primary outcomes reaches the preplanned effect size with sufficient statistical certainty. In this paper, we describe PIKASO elements according to the Standard Protocol Items: Recommendations for Interventional Trials (SPIRIT) guidelines.

Results

Our multidisciplinary team developed the methods and statistical analysis plan for a placebo controlled, randomized clinical trial to determine whether metformin alters pain and early osteoarthritic changes after ACLR.

Discussion

This manuscript outlines the rationale, study design, and implementation of the PIKASO trial aiming to prevent the onset of PTOA after ACLR.

Trial registration

clinicaltrials.gov NCT06096259.

Platelet signaling in immune landscape: comprehensive mechanism and clinical therapy

Platelets are essential for blood clotting and maintaining normal hemostasis. In pathological conditions, platelets are increasingly recognized as crucial regulatory factors in various immune-mediated inflammatory diseases. Resting platelets are induced by various factors such as immune complexes through Fc receptors, platelet-targeting autoantibodies and other platelet-activating stimuli. Platelet activation in immunological processes involves the release of immune activation stimuli, antigen presentation and interaction with immune cells. Platelets participate in both the innate immune system (neutrophils, monocytes/macrophages, dendritic cells (DCs) and Natural Killer (NK) cells and the adaptive immune system (T and B cells). Clinical therapeutic strategies include targeting platelet activation, platelet-immune cell interaction and platelet-endothelial cell interaction, which display positive development prospects. Understanding the mechanisms of platelets in immunity is important, and developing targeted modulations of these mechanisms will pave the way for promising therapeutic strategies.

Metformin and fibromyalgia pathophysiology: current insights and promising future therapeutic strategies

Fibromyalgia (FM) is a complex, chronic pain syndrome characterized by widespread musculoskeletal pain, fatigue, and cognitive disturbances. Despite its prevalence, the pathophysiology of FM remains poorly understood, with current treatments often providing limited relief. Recent studies have suggested that metformin, a widely used antidiabetic drug, may have potential therapeutic benefits for chronic pain conditions, including FM. This review aims to provide current insights into the role of metformin in FM pathophysiology, focusing on its neurotransmitter-modulating and anti-inflammatory effects. Metformin has been shown to mitigate neuroinflammation, protect neural tissues, and modulate key neurotransmitters involved in pain and mood regulation. These effects are particularly evident in animal models, where metformin has been observed to reduce pain sensitivity, improve mood-related behaviors, and decrease levels of pro-inflammatory cytokines like interleukin 1-beta (IL-1β). Additionally, the ability of metformin to influence serotonin, norepinephrine, and glutamate levels suggests a potential mechanism for its analgesic and mood-stabilizing effects. However, the current evidence is largely preclinical, and further research is needed to confirm these findings in human studies. This review aims to encourage researchers to explore the association between metformin and FM more deeply, with the hope of uncovering new therapeutic strategies that could offer relief to FM patients.

Rheumatic diseases and metabolism: where centre and periphery meet

Over the past few decades, the connection between metabolism and various inflammatory and rheumatic diseases has been an area of active investigation. Nonetheless, the precise mechanisms underlying these relationships remain a topic of ongoing debate, owing in part to conflicting data. This discrepancy can be attributed to the predominant focus on peripheral mechanisms in research into the metabolic consequences of rheumatic diseases. However, a wealth of evidence supports the notion that the central nervous system, specifically the hypothalamus, has an important influence on metabolic homeostasis. Notably, links have been established between crucial hypothalamic mechanisms responsible for regulating energy balance (including food intake, thermogenesis, and glucose and lipid metabolism), such as AMP-activated protein kinase, and the pathophysiology of rheumatoid arthritis. This Review aims to comprehensively examine the current understanding of central metabolic control in rheumatic diseases and explore potential therapeutic options that target this pathophysiological mechanism.

Shikonin suppresses rheumatoid arthritis by inducing apoptosis and autophagy via modulation of the AMPK/mTOR/ULK-1 signaling pathway

BACKGROUND

The overproliferation of fibroblast-like synoviocytes (FLS) contributes to synovial hyperplasia, a pivotal pathological feature of rheumatoid arthritis (RA). Shikonin (SKN), the active compound from Lithospermum erythrorhizon, exerts anti-RA effects by diverse means. However, further research is needed to confirm SKN's in vitro and in vivo anti-proliferative functions and reveal the underlying specific molecular mechanisms.

PURPOSE

This study revealed SKN's anti-proliferative effects by inducing both apoptosis and autophagic cell death in RA FLS and adjuvant-induced arthritis (AIA) rat synovium, with involvement of regulating the AMPK/mTOR/ULK-1 pathway.

METHODS

SKN's influences on RA FLS were assessed for proliferation, apoptosis, and autophagy with immunofluorescence staining (Ki67, LC3B, P62), EdU incorporation assay, staining assays of Hoechst, Annexin V-FITC/PI, and JC-1, transmission electron microscopy, mCherry-GFP-LC3B puncta assay, and western blot. In AIA rats, SKN's anti-arthritic effects were assessed, and its impacts on synovial proliferation, apoptosis, and autophagy were studied using Ki67 immunohistochemistry, TUNEL, and western blot. The involvement of AMPK/mTOR/ULK-1 pathway was examined via western blot.

RESULTS

SKN suppressed RA FLS proliferation with reduced cell viability and decreased Ki67-positive and EdU-positive cells. SKN promoted RA FLS apoptosis, as evidenced by apoptotic nuclear fragmentation, increased Annexin V-FITC/PI-stained cells, reduced mitochondrial potential, elevated Bax/Bcl-2 ratio, and increased cleaved-caspase 3 and cleaved-PARP protein levels. SKN also enhanced RA FLS autophagy, featuring increased LC3B, reduced P62, autophagosome formation, and activated autophagic flux. Autophagy inhibition by 3-MA attenuated SKN's anti-proliferative roles, implying that SKN-induced autophagy contributes to cell death. In vivo, SKN mitigated the severity of rat AIA while also reducing Ki67 expression, inducing apoptosis, and enhancing autophagy within AIA rat synovium. Mechanistically, SKN modulated the AMPK/mTOR/ULK-1 pathway in RA FLS and AIA rat synovium, as shown by elevated P-AMPK and P-ULK-1 expression and decreased P-mTOR expression. This regulation was supported by the reversal of SKN's in vitro and in vivo effects upon co-administration with the AMPK inhibitor compound C.

CONCLUSION

SKN exerted in vitro and in vivo anti-proliferative properties by inducing apoptosis and autophagic cell death via modulating the AMPK/mTOR/ULK-1 pathway. Our study revealed novel molecular mechanisms underlying SKN's anti-RA effects.

AMPK, a key molecule regulating aging-related myocardial ischemia-reperfusion injury

Aging leads to the threat of more diseases to the biological anatomical structure and the decline of disease resistance, increasing the incidence and mortality of myocardial ischemia-reperfusion injury (MI/RI). Moreover, MI/RI promotes damage to an aging heart. Notably, 5'-adenosine monophosphate-activated protein kinase (AMPK) regulates cellular energy metabolism, stress response, and protein metabolism, participates in aging-related signaling pathways, and plays an essential role in ischemia-reperfusion (I/R) injury diseases. This study aims to introduce the aging theory, summarize the interaction between aging and MI/RI, and describe the crosstalk of AMPK in aging and MI/RI. We show how AMPK can offer protective effects against age-related stressors, lifestyle factors such as alcohol consumption and smoking, and hypertension. We also review some of the clinical prospects for the development of interventions that harness the effect of AMPK to treat MI/RI and other age-related cardiovascular diseases.

Efficacy of montelukast as an adjuvant therapy in rheumatoid arthritis patients: A randomized controlled study

OBJECTIVE

This study aimed to evaluate the efficacy of montelukast in conjunction with non-biologic disease modifying anti-rheumatic drugs (nDMARDs) in rheumatoid arthritis (RA) patients.

METHODS

This study was a single-center randomized double-blinded placebo-controlled study. Adult RA patients were included if they had moderate to severe disease activity and were receiving monotherapy or combination of nDMARDs. Eligible patients were randomized, in 1:1 ratio, to receive either 10 mg montelukast or placebo, once daily for 16 weeks. The primary endpoint was the change in the 28-joints disease activity score (DAS28) 16 weeks after treatment. The patients' quality of life (QoL) was assessed by the Arabic version of the Health Assessment Questionnaire-Disability Index. Moreover, serum levels of vascular adhesion molecule-1 (VCAM-1) were measured.

RESULTS

A total of 87 patients completed the study; 44 in the montelukast arm and 43 in the control arm. After 16 weeks of treatment, disease activity decreased significantly in the montelukast arm with mean change in DAS28 (95% CIs) of -1.5 (-1.7, -1.2) while the control arm showed no improvement (0.2 (0.0, 0.4), p < 0.01). The QoL of the patients improved significantly from baseline in the montelukast arm (p < 0.01) but not in the control arm (p = 0.08). The median (IQR) serum levels of VCAM-1 were significantly lower in the montelukast arm (22.8 (15.0-32.7)) than in the control arm (28.9 (15.4-42.8), p = 0.004).

CONCLUSION

The co-administration of montelukast with nDMARDs in RA patients enhanced the anti-rheumatic effect which was reflected clinically by decreased disease activity.

Regulatory T Cell-Targeted Immunomodulatory Therapy for Long-Term Clinical Improvement of Atopic Dermatitis: Hypotheses and Perspectives

Atopic dermatitis (AD) is a chronically relapsing inflammatory skin disorder characterized by itching and eczematous lesions. It is often associated with a personal or familial history of allergic diseases. Allergic inflammation induced by immunoglobulin E and T-helper type 2 (Th2) cell responses to common environmental agents has been suggested to play an essential role in AD pathogenesis. The standard therapies for AD, including topical or systemic agents, focus on controlling skin inflammation. Recently developed monoclonal antibody to interleukin-4 receptor alpha or Janus kinase inhibitors can provide significant clinical improvements in patients with AD by inhibiting Th2 cell-mediated skin inflammation. However, the clinical efficacy of the Th2 cell-targeted therapy is transient and incomplete in patients with AD. Patients with AD are seeking a permanent cure. Therefore, the development of novel immunomodulatory strategies that can improve a long-term clinical outcome and provide a long-term treatment-free clinical remission of AD (disease-modifying therapy) is needed. Regulatory T (Treg) cells play a critical role in the maintenance of immune tolerance and suppress the development of autoimmune and allergic diseases. This review provides three working hypotheses and perspectives for the treatment of AD by Treg cell activation. (1) A decreased number or function of Treg cells is a critical event that causes the activation of Th2 cells, leading to the development and maintenance of AD. (2) Activation of Treg cells is an effective therapeutic approach for AD. (3) Many different immunomodulatory strategies activating Treg cells can provide a long-term clinical improvement of AD by induction of immune tolerance. The Treg cell-targeted immunomodulatory therapies for AD include allergen immunotherapy, microbiota, vitamin D, polyvalent human immunoglobulin G, monoclonal antibodies to the surface antigens of T cell or antigen-presenting cell, and adoptive transfer of autologous Treg cells or genetically engineered Treg cells expanded in vitro.

Efficacy of metformin in prevention of paclitaxel-induced peripheral neuropathy in breast cancer patients: a randomized controlled trial

Background: Paclitaxel-induced peripheral neuropathy (PN) is a serious clinical problem with no approved drug for prevention. This study aimed to examine the neuroprotective effect of metformin against paclitaxel-induced PN in breast cancer patients. Methods: Patients with confirmed breast cancer diagnosis who were planned to receive paclitaxel were randomized to receive either metformin or placebo. Both groups received the standard chemotherapy protocol for breast cancer. Patients started metformin/placebo 1 week before paclitaxel initiation and continued study interventions thereafter for nine consecutive weeks. The primary outcome was the incidence of development of grade two or more paclitaxel-induced sensory PN. The PN was graded according to the National Cancer Institute Common Terminology Criteria for Adverse Events (NCI-CTCAE). Patients' quality of life (QoL) was assessed by the Functional Assessment of Cancer Therapy/Gynecologic Oncology Group-Neurotoxicity (FACTGOG-Ntx) subscale. Pain severity was measured by the Brief Pain Inventory Short Form (BPI-SF). Serum levels of nerve growth factor (NGF) and neurotensin (NT) were measured at baseline and at the end paclitaxel treatment. Results: A total of 73 patients (36 in the metformin arm and 37 in the control arm) were evaluated. The cumulative incidence of development of grade two or more PN was significantly lower in the metformin arm (14 (38.9%) than the control arm (28 (75.7%); p = 0.001). At the end of paclitaxel treatment, patients' QoL was significantly better in the metformin arm [median (IQR) FACTGOG-Ntx subscale of (24.0 (20.5-26.5)] compared to the control arm (21.0 (18.0-24.0); p = 0.003). The metformin arm showed lower "average" and "worst" pain scores than those detected in the control arm. At the end of the paclitaxel treatment, there was a significant difference in the median serum NGF levels between the two arms, favoring metformin (p < 0.05), while NT serum levels were deemed comparable between the two study arms (p = 0.09). Conclusion: The use of metformin in breast cancer patients offered a marked protection against paclitaxel-induced PN, which translated to better patient QoL. Clinical Trial Registration: https://classic.clinicaltrials.gov/ct2/show/NCT05351021, identifier NCT05351021.

Metformin Treatment Reduces the Incidence of Rheumatoid Arthritis: A Two-Sample Mendelian Randomized Study

Several studies have shown that rheumatologic patients can benefit from metformin, but it remains unclear whether metformin treatment is causally associated with the risk of rheumatoid arthritis (RA). A two-sample Mendelian randomization (MR) study was conducted to investigate the causal relationship between metformin treatment and the incidence of rheumatoid arthritis. The genome-wide significant (p < 5 × 10^-8) single-nucleotide polymorphisms (SNPs) associated with metformin use were selected as instrumental variables (IVs). Summary statistics on RA were extracted from a large genome-wide association study (GWAS) meta-analysis. The inverse variance-weighted (IVW) method was used as the determinant of the causal effects of metformin treatment on RA. Cochran's Q was used to detect heterogeneity. Mendelian randomization pleiotropy residual sum and outlier (MR-PRESSO) test and MR-Egger regression were used to detect horizontal pleiotropy. A total of 34 SNPs significantly associated with metformin treatment were obtained. Thirty-two SNPs were selected as IVs after removing two SNPs for being palindromic with intermediate allele frequencies (rs11658063 and rs4930011). The IVW results showed a negative causal association between metformin treatment and RA (OR = 0.0232, 95% CI 1.6046 × 10^-3 - 0.3368; p = 0.006). Meanwhile, no heterogeneity or pleiotropy was detected, indicating that the results were reliable. This study indicated a negative causality between metformin treatment and RA, indicating that the treatment of metformin can prevent the pathogenesis of RA.

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.

Cellular metabolic adaptations in rheumatoid arthritis and their therapeutic implications

Activation of endothelium and immune cells is fundamental to the initiation of autoimmune diseases such as rheumatoid arthritis (RA), and it results in trans-endothelial cell migration and synovial fibroblast proliferation, leading to joint destruction. In RA, the synovial microvasculature is highly dysregulated, resulting in inefficient oxygen perfusion to the synovium, which, along with the high metabolic demands of activated immune and stromal cells, leads to a profoundly hypoxic microenvironment. In inflamed joints, infiltrating immune cells and synovial resident cells have great requirements for energy and nutrients, and they adapt their metabolic profiles to generate sufficient energy to support their highly activated inflammatory states. This shift in metabolic capacity of synovial cells enables them to produce the essential building blocks to support their proliferation, activation and invasiveness. Furthermore, it results in the accumulation of metabolic intermediates and alteration of redox-sensitive pathways, affecting signalling pathways that further potentiate the inflammatory response. Importantly, the inflamed synovium is a multicellular tissue, with cells differing in their metabolic requirements depending on complex cell-cell interactions, nutrient supply, metabolic intermediates and transcriptional regulation. Therefore, understanding the complex interplay between metabolic and inflammatory pathways in synovial cells in RA will provide insight into the underlying mechanisms of disease pathogenesis.

Metformin and its therapeutic applications in autoimmune inflammatory rheumatic disease

Metformin is a first-line therapeutic agent for type 2 diabetes. Apart from its glucose-lowering effect, metformin is attracting interest regarding possible therapeutic benefits in various other conditions. As metformin regulates cell metabolism, proliferation, growth, and autophagy, it may also modulate immune cell functions. Given that metformin acts on multiple intracellular signaling pathways, including adenosine monophosphate (AMP)-activated protein kinase (AMPK) activation, and that AMPK and its downstream intracellular signaling control the activation and differentiation of T and B cells and inflammatory responses, metformin may exert immunomodulatory and anti- inflammatory effects. The efficacy of metformin has been investigated in preclinical and clinical studies on rheumatoid arthritis, osteoarthritis, systemic lupus erythematosus, Sjögren's syndrome, scleroderma, ankylosing spondylitis, and gout. In this review, we discuss the potential mechanisms through which metformin exerts its therapeutic effects in these diseases, focusing particularly on rheumatoid arthritis and osteoarthritis.

Metabolites as drivers and targets in Rheumatoid Arthritis

Rheumatoid arthritis (RA) is a chronic autoimmune disease characterized by neovascularization, immune cell infiltration, and synovial hyperplasia, which leads to degradation of articular cartilage and bone, and subsequent functional disability. Dysregulated angiogenesis, synovial hypoxia, and immune cell infiltration result in a ‘bioenergetic crisis’ in the inflamed joint which further exacerbates synovial invasiveness. Several studies have examined this vicious cycle between metabolism, immunity, and inflammation and the role metabolites play in these interactions. To add to this complexity, the inflamed synovium is a multicellular tissue with many cellular subsets having different metabolic requirements. Metabolites can shape the inflammatory phenotype of immune cell subsets during disease and act as central signalling hubs. In the RA joint, the increased energy demand of stromal and immune cells leads to the accumulation of metabolites such as lactate, citrate, and succinate as well as adipocytokines which can regulate downstream signalling pathways. Transcription factors such as HIF1ɑ and mTOR can act as metabolic sensors to activate synovial cells and drive pro-inflammatory effector function, thus perpetuating chronic inflammation further. These metabolic intermediates may be potential therapeutic targets and so understanding the complex interplay between metabolites and synovial cells in RA may allow for identification of novel therapeutic strategies but also may provide significant insight into the underlying mechanisms of disease pathogenesis.