Metformin Attenuates the Inflammatory Response via the Regulation of Synovial M1 Macrophage in Osteoarthritis

Regulation of macrophage polarization by metformin through inhibition of TLR4/NF-κB pathway to improve pre-eclampsia

INTRODUCTION

Pre-eclampsia (PE) is a pregnancy complication featuring hypertension and proteinuria. Metformin exerts clinically preventive effects on PE with an unspecified mechanism.

METHODS

Placental tissues from PE patients and normal pregnant (NP) women were collected. Twenty-four pregnant mice were divided into control, PE (40 μg/kg lipopolysaccharides (LPS)-induced modeling), aspirin, and metformin groups. After acquisition of bone marrow-derived macrophages (BMDM) and THP-1 cells, cells were categorized into control, LPS (100 ng/mL), metformin, and metformin + toll-like receptor 4 (TLR4) agonist RS 09 groups. Inflammatory factors and macrophage polarization were detected by ELISA, flow cytometry, immunofluorescence, immunohistochemistry, and qRT-PCR methods. TLR4/Nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) pathway protein expression was examined using Western blot.

RESULTS

Both PE patients and PE-like mice enhanced inducible nitric oxide synthase (iNOS), TLR4, p-NF-κB/NF-κB, and p-inhibitor of NF-κB (IκBα)/IκBα expression, and lower arginase 1 (Arg-1) expression. Moreover, metformin treatment in PE-like mice increased fetal number and weight and reduced hypertension, proteinuria, insulin resistance, tumor necrosis factor-α (TNF-α), IL-6, IL-1β, chemokine ligand 4 (CCL4), C-X-C motif chemokine ligand 2 (CXCL2) expression and M1 macrophage polarization, with similar inhibition to aspirin. In LPS-induced cells, metformin had the same effects mentioned above. Decreased TLR4, p-NF-κB/NF-κB, and p-IκBα/IκBα protein expression was caused by metformin both in vivo and in vitro. In vitro, RS 09 intervention inhibited anti-inflammatory and pro-M2 polarizing effects of metformin, activating TLR4/NF-κB pathway.

CONCLUSION

Metformin may ameliorate PE by promoting M2 macrophage polarization through up-regulating TLR4/NF-κB pathway, laying theoretical basis for metformin clinical application in PE.

Biocompatible ionized air alleviates rat osteoarthritis by modulating polarization from M1 to M2 macrophages

The imbalance in the proportion of M1/M2 macrophage polarization is a crucial contributor to the persistent progression of osteoarthritis (OA). This study aimed to evaluate the effects of low-dose biocompatible ionized air (BIA) on macrophage polarization and its subsequent chondroprotective effects, thereby validating the potential of BIA in slowing the progression of OA. In vitro experiments demonstrated that BIA modulates the polarization of M1 macrophages toward the M2 phenotype via the ROS-mediated STAT6 pathway. This shift reduces the expression of pro-inflammatory mediators while increasing the expression of anti-inflammatory mediators and pro-chondrogenic factors, leading to an improved microenvironment surrounding chondrocytes. The direct benefits of this improved microenvironment include enhanced chondrocyte viability, inhibition of apoptosis, and reduced degradation of the extracellular matrix. In vivo studies in rats showed that BIA inhibited M1 macrophage infiltration in the synovium, upregulated the proportion of M2 macrophages, alleviated cartilage degeneration, and delayed OA progression. This gas-based regulatory strategy may open new avenues for the treatment of OA.

The role of macrophage polarization in rheumatoid arthritis and osteoarthritis: Pathogenesis and therapeutic strategies

Rheumatoid arthritis (RA) and osteoarthritis (OA) are common and debilitating joint disorders affecting millions of individuals worldwide. Despite their distinct pathological features, both conditions share a crucial role of macrophages in disease progression. Macrophages exhibit remarkable plasticity, polarizing into pro-inflammatory M1 or anti-inflammatory M2 phenotypes in response to environmental cues. An imbalance in macrophage polarization, particularly a shift towards the M1 phenotype, contributes to chronic inflammation and joint damage in RA and OA. This review explores the complex interplay between macrophages and various cell types, including T cells, B cells, synovial fibroblasts, osteoclasts, chondrocytes, and adipocytes, in the pathogenesis of these diseases. We discuss the current understanding of macrophage polarization in RA and OA, highlighting the molecular mechanisms involved. Furthermore, we provide an overview of potential therapeutic strategies targeting macrophage polarization, such as disease-modifying anti-rheumatic drugs, traditional Chinese medicine, nanomedicines, proteins, chemical compounds, and physical therapies. By elucidating the precise mechanisms governing macrophage polarization and its interactions with other cells in the joint microenvironment, researchers can identify novel therapeutic targets and develop targeted interventions to alleviate disease progression and improve patient outcomes in RA and OA.

Is there a genetic relationship between blood glucose and osteoarthritis? A mendelian randomization study

OBJECTIVE

The relationship between blood glucose levels and osteoarthritis (OA) is unclear. This study aimed to investigate the genetic causal relationship between blood glucose-related traits and OA.

METHODS

We first performed univariate Mendelian randomization (UVMR) analyses using published genome-wide association study (GWAS) datasets with fasting glucose (FG), 2 h-glucose post-challenge glucose (2hGlu), and glycosylated hemoglobin (HbA1c) as exposures, and hip osteoarthritis (HOA) and knee osteoarthritis (KOA) as outcomes; then, we performed inverse analyses of them. We used Inverse-variance weighted (IVW) analysis as the primary analysis, and sensitivity analyses were performed. Moreover, we performed multivariate Mendelian randomization (MVMR) to estimate the independent effect of exposure on outcome after adjusting for body mass index (BMI). Summarized data for blood glucose-related traits were obtained from the MAGIC Consortium study of the glucose trait genome and for OA from the UK Biobank and arcOGEN. Summarized data for BMI were obtained from the GIANT Consortium meta-analysis of individuals of European ancestry. A two-sided p value < 0.05 in UVMR was considered suggestive of significance when p < 0.0167 (Bonferroni correction p = 0.05/3 exposures) was considered statistically significant.

RESULTS

We found significant negative genetic causality of FG for HOA and KOA, and these associations remained significant after we adjusted for the effect of BMI [odds ratios (ORs) of 0.829 (0.687-0.999, p = 0.049) and 0.741 (0.570-0.964, p = 0.025)]. HbA1c also had an independent negative genetic causal effect on HOA after adjustment for BMI [0.665 (0.463-0.954, p = 0.027)]. At the same time, there was no evidence of reverse genetic causality of OA on blood glucose-related traits.

CONCLUSION

We further elucidated the relationship between blood glucose-related traits and OA by adjusting for the effect of BMI from a genetic causal perspective. This study provides new insights to further clarify the relationship between blood glucose levels and OA, as well as the pathogenesis, etiology and genetics of OA.

Emerging Roles of Macrophage Polarization in Osteoarthritis: Mechanisms and Therapeutic Strategies

Osteoarthritis (OA) is the most common chronic degenerative joint disease in middle-aged and elderly people, characterized by joint pain and dysfunction. Macrophages are key players in OA pathology, and their activation state has been studied extensively. Various studies have suggested that macrophages might respond to stimuli in their microenvironment by changing their phenotypes to pro-inflammatory or anti-inflammatory phenotypes, which is called macrophage polarization. Macrophages accumulate and become polarized (M1 or M2) in many tissues, such as synovium, adipose tissue, bone marrow, and bone mesenchymal tissues in joints, while resident macrophages as well as other stromal cells, including fibroblasts, chondrocytes, and osteoblasts, form the joint and function as an integrated unit. In this study, we focus exclusively on synovial macrophages, adipose tissue macrophages, and osteoclasts, to investigate their roles in the development of OA. We review recent key findings related to macrophage polarization and OA, including pathogenesis, molecular pathways, and therapeutics. We summarize several signaling pathways in macrophage reprogramming related to OA, including NF-κB, MAPK, TGF-β, JAK/STAT, PI3K/Akt/mTOR, and NLRP3. Of note, despite the increasing availability of treatments for osteoarthritis, like intra-articular injections, surgery, and cellular therapy, the demand for more effective clinical therapies has remained steady. Therefore, we also describe the current prospective therapeutic methods that deem macrophage polarization to be a therapeutic target, including physical stimulus, chemical compounds, and biological molecules, to enhance cartilage repair and alleviate the progression of OA.

Songorine modulates macrophage polarization and metabolic reprogramming to alleviate inflammation in osteoarthritis

Introduction

Osteoarthritis (OA) is a prevalent joint disorder characterized by multifaceted pathogenesis, with macrophage dysregulation playing a critical role in perpetuating inflammation and joint degeneration.

Methods

This study focuses on Songorine, derived from Aconitum soongaricum Stapf, aiming to unravel its therapeutic mechanisms in OA. Comprehensive analyses, including PCR, Western blot, and immunofluorescence, were employed to evaluate Songorine's impact on the joint microenvironment and macrophage polarization. RNA-seq analysis was conducted to unravel its anti-inflammatory mechanisms in macrophages. Metabolic alterations were explored through extracellular acidification rate monitoring, molecular docking simulations, and PCR assays. Oxygen consumption rate measurements were used to assess mitochondrial oxidative phosphorylation, and Songorine's influence on macrophage oxidative stress was evaluated through gene expression and ROS assays.

Results

Songorine effectively shifted macrophage polarization from a pro-inflammatory M1 phenotype to an anti-inflammatory M2 phenotype. Notably, Songorine induced metabolic reprogramming, inhibiting glycolysis and promoting mitochondrial oxidative phosphorylation. This metabolic shift correlated with a reduction in macrophage oxidative stress, highlighting Songorine's potential as an oxidative stress inhibitor.

Discussion

In an in vivo rat model of OA, Songorine exhibited protective effects against cartilage damage and synovial inflammation, emphasizing its therapeutic potential. This comprehensive study elucidates Songorine's multifaceted impact on macrophage modulation, metabolic reprogramming, and the inflammatory microenvironment, providing a theoretical foundation for its therapeutic potential in OA.

A New Cell Model Overexpressing sTGFBR3 for Studying Alzheimer's Disease In vitro

BACKGROUND

Recent studies have suggested that abnormal microglial hyperactivation has an important role in the progression of Alzheimer's disease (AD). sTGFBR3 (a shed extracellular domain of the transforming growth factor type III receptor) is a newly identified target of microglia polarization dysregulation, whose overexpression can cause abnormal accumulation of transforming growth factor β1 (TGF-β1), promoting Aβ, tau, and neuroinflammatory pathology.

OBJECTIVE

The objective of this study is to develop and validate a new cell model overexpressing sTGFBR3 for studying AD in vitro.

METHODS

BV2 cells (a microglial cell derived from C57/BL6 murine) were used as a cell model. Cells were then treated with different concentrations of lipopolysaccharide (LPS) (0, 1, or 0.3 μg/mL) for 12, 24, or 48h and then with or without sodium pervanadate (100 μM) for 30 min. Next, the effect surface optimization method was used to determine optimal experimental conditions. Finally, the optimized model was used to assess the effect of ZQX series compounds and vasicine on cell viability and protein expression. Expression of TGFBR3 and TNF-α was assessed using Western blot. MTT assay was used to assess cell viability, and enzyme- linked immunosorbent assay (ELISA) was employed to evaluate extracellular TGF-β1 and sTGFBR3.

RESULTS

LPS (0.3 μg/mL) treatment for 11 h at a cell density of 60% and pervanadate concentration (100 μM) incubation for 30 min were the optimal experimental conditions for increasing membrane protein TGFBR3 overexpression, as well as extracellular sTGFBR3 and TGF-β1. Applying ZQX-5 and vasicine reversed this process by reducing extracellular TGF-β1, promoting the phosphorylation of Smad2/3, a protein downstream of TGF-β1, and inhibiting the release of the inflammatory factor TNF-α.

CONCLUSION

This new in vitro model may be a useful cell model for studying Alzheimer's disease in vitro.

In Vitro and In Vivo Evaluation of Metformin Hydrochloride Hydrogels Developed with Experimental Design in the Treatment of Burns

Burns alter the normal skin barrier and affect various host defense processes that help prevent infections. An ineffective repair process can lead to serious damage, such as the onset of an infection or skin loss, which can then harm the surrounding tissues and ultimately the entire organism. This study aims to prepare in situ gels containing metformin hydrochloride, a compound known for its wound healing properties. To achieve this, in situ gels were prepared using three different gelling agents (Poloxamer 407®, Carbopol 934®, and sodium carboxymethyl cellulose (Na-CMC)) and three different concentrations of metformin hydrochloride (4 mg/g, 6 mg/g, and 8 mg/g), which were optimized through experimental design. Metformin concentration and gelling agent type were independent variables, and the loaded amount and the percentage of metformin released after 150 min were chosen as dependent variables in the optimization process. After determining the optimum values of the dependent variables according to the ANOVA analysis results, in vivo studies were conducted with optimized hydrogel formulations. Two groups, each consisting of seven Wistar rats with a burn model, were treated with metformin-poloxamer 407® gels at doses of 4 mg/g and 8 mg/g for 29 days. The results were then compared to untreated and placebo gel groups. Rats treated with in situ Poloxamer 407® hydrogels containing metformin hydrochloride showed a significant reduction in the size of the burned area after 29 days of treatment. However, for a comprehensive understanding of the wound healing mechanism, further studies such as immuno-histochemical and cell culture studies are needed.

Macrophage polarization in osteoarthritis progression: a promising therapeutic target

Osteoarthritis (OA) is one of the leading causes of pain and disability in the elderly. Synovitis, cartilage destruction and osteophyte formation histologically manifest OA. Unfortunately, there is currently no effective therapy to delay its progression and the underlying mechanisms of OA require further exploration. Macrophage is a main cellular component of joint synovium. It is highly plastic and can be stimulated to polarize to different phenotypes, namely, the pro-inflammatory phenotype (M1) and the anti-inflammatory/tissue-repairing phenotype (M2). Ample evidence has demonstrated the vital roles of macrophages in the progression of OA. Imbalanced M1/M2 ratio is significantly related to OA severity indicating macrophage polarization might be a promising therapeutic target for OA. In this review, we summarized the involvements of polarized macrophages in synovitis, cartilage degradation, osteophyte formation and OA-related chronic pain. Promising therapies targeting macrophage polarization including the intra-articular cell/derivates-based therapy and the alternative non-invasive intervention such as photobiomodulation therapy were reviewed as well.