Apoptotic cell clearance components in inflammatory arthritis

Emodin delays rheumatoid arthritis progression by inhibiting the ROS/TXNIP/NLRP3 signaling pathway

Rheumatoid arthritis (RA) is a chronic autoimmune disorder affecting small joints of the hands, feet, and ankles, causing synovitis, pannus formation, and vasculitis. RA can lead to joint destruction and multi-system complications. Emodin (EMO), the primary active component of rhubarb, has significant anti-inflammatory properties and therapeutic potential in alleviating RA symptoms. This study focused on this therapeutic efficacy and underlying mechanisms. Collagen-induced arthritis (CIA) mouse models and lipopolysaccharide (LPS)-stimulated RAW264.7 cells were used to investigate the effects of EMO on pathological markers, inflammatory factors, and oxidative stress through histopathological analysis, western blotting, micro-computed tomography (CT), and immunohistochemistry (IHC). Proteomics, molecular docking, and molecular dynamics (MD) simulations were used to identify key targets and to elucidate the mechanisms of action underlying the therapeutic efficacy of EMO. EMO alleviated joint swelling, reduced arthritis scores, and mitigated bone damage in mice with CIA. EMO significantly decreased inflammatory factor levels and attenuated oxidative stress, as shown through reduced reactive oxygen species (ROS) and malondialdehyde (MDA) levels and increased superoxide dismutase (SOD) activity. EMO inhibited inflammasome activation, as indicated by reduced NOD-, LRR-, and pyrin domain-containing protein 3 (NLRP3), caspase-1, apoptosis-associated speck-like protein containing a CARD (ASC), interleukin (IL)-1β, and IL-18 expression. The analyses showed that the anti-inflammatory effects of EMO are mediated through ROS/TXNIP/NLRP3 signaling pathway inhibition. Collectively, EMO downregulated inflammatory responses and oxidative stress, inhibited inflammasome activation, and alleviated RA symptoms through ROS/TXNIP/NLRP3 signaling pathway suppression. These findings highlight its potential for RA treatment and provide insights into its mechanisms and clinical applications.

Efferocytosis at the frontline of homeostasis: Shaping the bone microenvironment and therapeutic implications in related diseases

Bone is a dynamic tissue that constantly undergoes remodeling processes throughout life to maintain its structure and integrity. During this process, physiological bone turnover, which is shaped by apoptosis, occurs in cells in the bone microenvironment. The clearance of these apoptotic cells (ACs) is executed by phagocytes through a process called efferocytosis, which simply means taking to the grave "burial." Efferocytosis is a multistage process involving the recognition, binding, internalization, and digestion of ACs, culminating in the resolution of inflammation. Critically, aberrations in efferocytosis lead to the accumulation of apoptotic corpses, impairing tissue homeostasis and contributing to various pathologies as well as bone-related diseases. Emerging evidence suggests that modulating/activating efferocytosis at any stage represents a promising therapeutic strategy for managing bone-related diseases, especially those associated with aging and inflammation. This review discusses the current understanding of the cellular and molecular mechanisms of efferocytosis, its roles within the bone microenvironment, and potential therapeutic interventions targeting efferocytosis in age-related bone diseases.

Unraveling the mechanisms of Shaoyang Shenggu decoction in treating knee osteoarthritis through mass spectrometry and bioinformatics

ETHNOPHARMACOLOGICAL RELEVANCE

KOA is a common chronic joint disease in orthopedics that leads to pain, stiffness, and functional limitations. Traditional Chinese medicine categorizes it under "bi syndrome," "wei syndrome," and "bone bi.".The theory that "Shaoyang governs the bones"is first recorded in the "Huangdi Neijing."Shaoyang Shenggu Fang has demonstrated favorable efficacy in repairing cartilage injury.

OBJECTIVE

To identify the active components of Shaoyang Shenggu Fang (SYSGF) and elucidate their mechanisms in the treatment of knee osteoarthritis (KOA) through mass spectrometry data combined with network pharmacology, bioinformatics, and single-cell analysis, and to perform preliminary validation of the results using clinical samples and animal experiments.

METHODS

The primary compounds in SYSGF were detected using UPLC-Q-TOF. Network pharmacology and bioinformatics analyses were employed to explore the mechanisms of SYSGF in KOA, identifying core targets and key pathways. Clinical samples were utilized to validate the expression levels of core genes during the KOA process. Micro-CT and pathological staining were conducted to assess the effects of SYSGF on cartilage degeneration in KOA animal models. WB and PCR were performed to confirm the expression levels of core genes and key pathways before and after treatment. Finally, single-cell analysis was conducted to further investigate the relationship between core genes and chondrocyte subpopulations.

RESULTS

A total of 46 active compounds from SYSGF were identified, and bioinformatics analyses determined five core targets (CYP1B1, VEGFA, NR4A1, BMP1, and FAP) and three key pathways (MAPK signaling pathway, HIF-1 signaling pathway, and PI3K-Akt signaling pathway). Validation with clinical samples revealed a significant increase in the expression levels of CYP1B1, NR4A1, and FAP in degenerated cartilage, while the expression levels of VEGFA and BMP1 were found to be decreased. Micro-CT and pathological staining revealed that SYSGF effectively alleviated cartilage damage caused by monosodium iodoacetate (MIA). Furthermore, SYSGF was found to inhibit the expression of CYP1B1, NR4A1, and FAP, while upregulating the expression of VEGFA and BMP1, thereby alleviating the progression of KOA and correlating with the MAPK signaling pathway, HIF-1 signaling pathway, and PI3K-Akt signaling pathway. Finally, we observed that the occurrence of KOA is closely related to the infiltration of various chondrocyte subtypes and immune regulation, with FCs, PreHTCs, and ProCs being the primary chondrocyte subtypes involved. CYP1B1, VEGFA, NR4A1, BMP1, and FAP play significant roles in chondrocyte phenotype transformation and inflammation.

CONCLUSION

SYSGF may inhibit chondrocyte phenotype transformation and inflammation to improve KOA by regulating these key proteins, and is associated with the MAPK signaling pathway, HIF-1 signaling pathway, and PI3K-Akt signaling pathway.

Myosin Light Chain 12b and MASP1 as Novel Biomarker Candidates in Active Juvenile Idiopathic Arthritis─A Combined Proteomics/Bioinformatics Approach

Current diagnostic methods for JIA lack specificity, often failing to distinguish it from other childhood diseases of similar clinical presentations. The present study is a comparative cross-sectional study that identified potential biomarkers using label-free mass spectrometry and bioinformatics. Two differentially expressed proteins (DEPs), Myosin light chain 12b (Myl12b) and Mannose-binding lectin serine protease 1 (MASP1), showed increased expression in JIA patients. Receiver operating characteristic (ROC) analysis revealed strong predictive power (AUC: Myl12b = 0.757, MASP1 = 0.855), validated in a separate cohort via Western blot and ELISA. These findings suggest Myl12b and MASP1 as promising biomarkers for JIA diagnosis and treatment. Data: ProteomeXchange (PXD058863).

Mechanism of action of Nrf2 and its related natural regulators in rheumatoid arthritis

Rheumatoid arthritis (RA) is an autoimmune disease characterized by synovitis that can lead to joint deformities. To date, more than 18 million individuals worldwide have been diagnosed with RA, making it one of the most prevalent autoimmune diseases globally and posing a significant threat to public health and safety. Due to the complex pathogenesis of the disease, which involves autoimmunity, genetics, inflammation and oxidative stress in the body's tissues, the current drug therapy generally targets a single molecule, and effective and efficient drugs involving multiple levels and targets are lacking; thus, there is an urgent need for high-quality research and treatment in this field. Nuclear transcription factor erythroid 2-associated factor 2 (Nrf2) plays a crucial role in cellular resistance to oxidative stress and electrophilic attacks and is a potential pharmacological target for chronic disease treatment. While currently no drugs that target Nrf2 have been approved specifically for RA treatment, such an approach holds great significance. In recent years, the use of natural products to treat RA and other chronic conditions has become increasingly widespread because of their superior efficacy and minimal side effects. Therefore, this article provides a review of the mechanism of Nrf2 in RA and summarizes natural products that target Nrf2 and its associated pathways in the treatment of RA, aiming to offer new insights and strategies for the prevention and management of RA.

Efferocytosis and Bone Dynamics

PURPOSE OF REVIEW

This review summarizes the recently published scientific evidence regarding the role of efferocytosis in bone dynamics and skeletal health.

RECENT FINDINGS

Several types of efferocytes have been identified within the skeleton, with macrophages being the most extensively studied. Efferocytosis is not merely a 'clean-up' process vital for maintaining skeletal homeostasis; it also plays a crucial role in promoting resolution pathways and orchestrating bone dynamics, such as osteoblast-osteoclast coupling during bone remodeling. Impaired efferocytosis has been associated with aging-related bone loss and various skeletal pathologies, including osteoporosis, osteoarthritis, rheumatoid arthritis, and metastatic bone diseases. Accordingly, emerging evidence suggests that targeting efferocytic mechanisms has the potential to alleviate these conditions. While efferocytosis remains underexplored in the skeleton, recent discoveries have shed light on its pivotal role in bone dynamics, with important implications for skeletal health and pathology. However, there are several knowledge gaps and persisting technical limitations that must be addressed to fully unveil the contributions of efferocytosis in bone.

Mechanism of Efferocytosis in Determining Ischaemic Stroke Resolution-Diving into Microglia/Macrophage Functions and Therapeutic Modality

After ischaemic cerebral vascular injury, efferocytosis-a process known as the efficient clearance of apoptotic cells (ACs) by various phagocytes in both physiological and pathological states-is crucial for maintaining central nervous system (CNS) homeostasis and regaining prognosis. The mechanisms of efferocytosis in ischaemic stroke and its influence on preventing inflammation progression from secondary injury were still not fully understood, despite the fact that the fundamental process of efferocytosis has been described in a series of phases, including AC recognition, phagocyte engulfment, and subsequent degradation. The genetic reprogramming of macrophages and brain-resident microglia after an ischaemic stroke has been equated by some researchers to that of the peripheral blood and brain. Based on previous studies, some molecules, such as signal transducer and activator of transcription 6 (STAT6), peroxisome proliferator-activated receptor γ (PPARG), CD300A, and sigma non-opioid intracellular receptor 1 (SIGMAR1), were discovered to be largely associated with aspects of apoptotic cell elimination and accompanying neuroinflammation, such as inflammatory cytokine release, phenotype transformation, and suppressing of antigen presentation. Exacerbated stroke outcomes are brought on by defective efferocytosis and improper modulation of pertinent signalling pathways in blood-borne macrophages and brain microglia, which also results in subsequent tissue inflammatory damage. This review focuses on recent researches which contain a number of recently discovered mechanisms, such as studies on the relationship between benign efferocytosis and the regulation of inflammation in ischaemic stroke, the roles of some risk factors in disease progression, and current immune approaches that aim to promote efferocytosis to treat some autoimmune diseases. Understanding these pathways provides insight into novel pathophysiological processes and fresh characteristics, which can be used to build cerebral ischaemia targeting techniques.

Combining bioinformatics, network pharmacology, and artificial intelligence to predict the mechanism of resveratrol in the treatment of rheumatoid arthritis

Background

Rheumatoid arthritis (RA) is a chronic autoimmune disorder that causes joint inflammation and destruction, resulting in significant physical and economic burdens. Finding effective and targeted therapy for RA remains a top priority. Resveratrol is a potential candidate with anti-inflammatory and immunomodulatory properties for RA treatment. This study aims to determine the therapeutic targets and signaling pathways of resveratrol in the treatment of RA.

Methods

The GSE205962 dataset downloaded from The Gene Expression Omnibus (GEO) database was used to obtain the differentially expressed genes (DEGs) in blood samples from the patients and the healthy. PharmMapper database and Cytoscape (v3.9.1) were applied to construct the resveratrol pharmacophore target network. Gene functional enrichment analysis, including the Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis, was based on the BiNGo plug-in of Cytoscape and David's online tool. The intersection of the target genes of resveratrol and the DEGs were considered potential therapeutic genes (PT-genes). The Protein-Protein Interaction (PPI) network of PT-genes was constructed using the STRING tool, and the key therapeutic genes (KT-genes) were determined using the cytoHubba plug-in based on the Maximal Clique Centrality (MCC) algorithms. Molecular docking validation of resveratrol and therapeutic targets was performed based on the protein structure of KT-genes predicted by AlphaFold.

Results

A total of 2202 DEGs and 47PT-genes were identified. GO analysis showed that the three groups of genes, the DEGs, the resveratrol target genes, and the PT-genes, have similar results for the top-five gene functional enrichment. PT-genes were closely related to the pathways of metabolic pathways, pathways in cancer, proteoglycans in cancer, insulin signaling pathway, and chemokine signaling pathway. The common pathway enriched by KEGG for the DEGs, and the resveratrol target genes was up to 36 %. The nine KT-genes were ABL1, ANXA5, CASP3, HSP90AA1, LCK, MAP2K1, MAPK1, PIK3R1, and RAC1, and the lowest free energy indicating the resveratrol/protein affinity were -8.4, -7.4, -6.4, -6.7, -8.0, -7.9, -7.4, -6.7, and -7.9, respectively.

Conclusion

Nine KT-genes were identified and validated as the most potential therapeutic targets in the treatment of RA with resveratrol, which provide new insights into therapeutic mechanisms and may improve the efficiency of drug development.

IL-17A/IL-17RA interaction blockade sensitizes synovial macrophages to efferocytosis and PD-L1 signaling via rewiring STAT-3/ADAM17/MERTK axis in rheumatoid arthritis animal model

Defective clearance of apoptotic cells due to impaired efferocytosis sustains error in self-tolerance that exacerbates rheumatoid arthritis (RA). However, the molecular determinant that directly or specifically impairs efferocytosis in RA is not yet studied. We identified a new perspective that IL-17A significantly impedes efferocytosis via preferential activation of the JAK/STAT-3/ADAM17 signaling axis. In contrast, disruption of the IL-17A/IL-17RA interaction using cyanidin or silencing of IL-17RA obstructed JAK/STAT-3 activation that further abolished ADAM17 expression. Subsequent depletion of ADAM17 inhibited the shedding of Mer tyrosine kinase receptor (MERTK), which significantly increased apoptotic cell intake and restored efferocytosis in adjuvant-induced arthritic (AA) model. Concomitantly, the amplification of the efferocytosis process due to IL-17A/IL-17RA interaction disruption was sensitive to mitochondrial fission mediated via Drp-1 phosphorylation downstream of STAT-3 inhibition. As expected, cyanidin treated AA synovial macrophages that exhibited increased efferocytosis demonstrated a phenotypic shift towards CD163 anti-inflammatory phenotype in a STAT-5 dependent manner. Similar results were obtained in IL-17A-sensitized AA synovial macrophages treated with S3I-201 (a STAT-3 inhibitor) indicating that IL-17A influences efferocytosis via the STAT-3 pathway. In view of our previous work where cyanidin restored Th17/Treg balance, our present investigation fulfils a critical gap by providing scientific validation that cyanidin escalated PD-L1 expression during the efferocytosis process that could have impacted the restoration of Th17/Treg balance in an AA model. Together, these data corroborate the hypothesis that IL-17A signaling can impair efferocytosis via regulating STAT-3/ADAM17/FL-MERTK axis and that its inhibition can amplify a pro-resolution signal against RA progression.

Efferocytosis in dendritic cells: an overlooked immunoregulatory process

Efferocytosis, the process of engulfing and removing apoptotic cells, plays an essential role in preserving tissue health and averting undue inflammation. While macrophages are primarily known for this task, dendritic cells (DCs) also play a significant role. This review delves into the unique contributions of various DC subsets to efferocytosis, highlighting the distinctions in how DCs and macrophages recognize and handle apoptotic cells. It further explores how efferocytosis influences DC maturation, thereby affecting immune tolerance. This underscores the pivotal role of DCs in orchestrating immune responses and sustaining immune equilibrium, providing new insights into their function in immune regulation.