Punicalagin ameliorates collagen-induced arthritis by downregulating M1 macrophage and pyroptosis via NF-κB signaling pathway

Potential mechanisms of rheumatoid arthritis therapy: Focus on macrophage polarization

Rheumatoid arthritis (RA) is an autoimmune inflammatory disease that affects multiple organs and systems in the human body, often leading to disability. Its pathogenesis is complex, and the long-term use of traditional anti-rheumatic drugs frequently results in severe toxic side effects. Therefore, the search for a safer and more effective antirheumatic drug is extremely important for the treatment of RA. As important immune cells in the body, macrophages are polarized. Under pathological conditions, macrophages undergo proliferation and are recruited to diseased tissues upon stimulation. In the local microenvironment, they polarize into different types of macrophages in response to specific factors and perform unique functions and roles. Previous studies have shown that there is a link between macrophage polarization and RA, indicating that certain active ingredients can ameliorate RA symptoms through macrophage polarization. Notably, Traditional Chinese medicine (TCM) monomer component and compounds demonstrate a particular advantage in this process. Building upon this insight, we reviewed and analyzed recent studies to offer valuable and meaningful insights and directions for the development and application of anti-rheumatic drugs.

Mesenchymal stem cells and their extracellular vesicles in bone and joint diseases: targeting the NLRP3 inflammasome

The nucleotide-binding oligomerization domain-like-receptor family pyrin domain-containing 3 (NLRP3) inflammasome is a cytosolic multi-subunit protein complex, and recent studies have demonstrated the vital role of the NLRP3 inflammasome in the pathological and physiological conditions, which cleaves gasdermin D to induce inflammatory cell death called pyroptosis and mediates the release of interleukin-1 beta and interleukin-18 in response to microbial infection or cellular injury. Over-activation of the NLRP3 inflammasome is associated with the pathogenesis of many disorders affecting bone and joints, including gouty arthritis, osteoarthritis, rheumatoid arthritis, osteoporosis, and periodontitis. Moreover, mesenchymal stem cells (MSCs) have been discovered to facilitate the inhibition of NLRP3 and maybe ideal for treating bone and joint diseases. In this review, we implicate the structure and activation of the NLRP3 inflammasome along with the detail on the involvement of NLRP3 inflammasome in bone and joint diseases pathology. In addition, we focused on MSCs and MSC-extracellular vesicles targeting NLRP3 inflammasomes in bone and joint diseases. Finally, the existing problems and future direction are also discussed.

Pomegranate (Punica granatum L.) phytochemicals target the components of metabolic syndrome

Pomegranate (Punica granatum L.) is a multipurpose dietary and medicinal plant known for its ability to promote various health benefits. Metabolic syndrome (MetS) is a complex metabolic disorder driving health and socioeconomic challenges worldwide. It may be characterized by insulin resistance, abdominal obesity, hypertension, and dyslipidemia. This study aims to conduct a review of pomegranate's effects on MetS parameters using a mechanistic approach relying on pre-clinical studies. The peel, juice, roots, bark, seeds, flowers, and leaves of the fruit present several bioactive compounds that are related mainly to anti-inflammatory and antioxidant activities as well as cardioprotective, antidiabetic, and antiobesity effects. The use of the juice extract can work as a potent inhibitor of angiotensin-converting enzyme activities, consequently regulating blood pressure. The major bioactive compounds found within the fruit are phenolic compounds (hydrolysable tannins and flavonoids) and fatty acids. Alkaloids, punicalagin, ellagitannins, ellagic acid, anthocyanins, tannins, flavonoids, luteolin, and punicic acid are also present. The antihyperglycemia, antihyperlipidemia, and weight loss promoting effects are likely related to the anti-inflammatory and antioxidant effects. When considering clinical application, pomegranate extracts are found to be frequently well-tolerated, further supporting its efficacy as a treatment modality. We suggest that pomegranate fruit, extract, or processed products can be used to counteract MetS-related risk factors. This review represents an important step towards exploring potential avenues for further research in this area.

The power of Punica granatum: A natural remedy for oxidative stress and inflammation; a narrative review

ETHNOPHARMACOLOGICAL RELEVANCE

Pomegranate 'Punica granatum' offers multiple health benefits, including managing hypertension, dyslipidemia, hyperglycemia, insulin resistance, and enhancing wound healing and infection resistance, thanks to its potent antioxidant and anti-inflammatory properties. It has been symbolized by life, health, femininity, fecundity, and spirituality.

AIM OF THE STUDY

Although laboratory and animal studies have been conducted on the healing effects of pomegranate, there needs to be a comprehensive review on its anti-oxidative and anti-inflammatory effects in chronic disorders. We aim to provide a comprehensive review of these effects based on in-vitro, in-vivo, and clinical studies conducted in managing various disorders.

MATERIALS AND METHODS

A comprehensive search of in-vitro, in-vivo, and clinical findings of pomegranate and its derivatives focusing on the highly qualified original studies and systematic reviews are carried out in valid international web databases, including Web of Science, PubMed, Scopus, and Cochrane Library.

RESULTS

Relevant studies have demonstrated that pomegranate and its derivatives can modulate the expression and activity of several genes, enzymes, and receptors through influencing oxidative stress and inflammation pathways. Different parts of pomegranate; roots, bark, blossoms, fruits, and leaves contain various bioactive compounds, such as polyphenols, flavonoids, anthocyanins, and ellagitannins, that have preventive and therapeutic effects against many disorders such as cardiovascular diseases, diabetes, neurological diseases, and cancers without any serious adverse effects.

CONCLUSIONS

Most recent scientific evidence indicates that all parts of the pomegranate can be helpful in treating a wide range of chronic disorders due to its anti-oxidative and anti-inflammatory activities. Since the safety of pomegranate fruit, juice, and extracts is established, further investigations can be designed by targeting its active antioxidant and anti-inflammatory constituents to discover new drugs.

Laggera alata Attenuates Inflammatory Response by Regulating Macrophage Polarization in Rheumatoid Arthritis Mice

Rheumatoid arthritis (RA) is a type of joint injury, which can induce the activation of inflammatory factors and polarization of tissue macrophages. Total phenolics from Laggera alata (TPLA) has been reported to exhibit anti-inflammatory effect in various diseases. However, its specific function in RA is still unknown. Here, the protective properties of TPLA were studied in collagen-induced arthritis (CIA)-induced RA mice. RA mouse model was established through the CIA induction. Arthritis score, hind paw thickness, and the body weight of the RA mice were evaluated in each group. H&E staining was conducted in hind paw and joint tissues for histopathological staining. The distal femur was analyzed by microCT, and bone loss-related indicators were assessed. The expression of macrophage polarization markers was detected by immunofluorescence staining in RA mice. The serum levels of inflammatory markers were determined by enzyme-linked immunosorbent assay (ELISA). TPLA reduced the CIA-induced arthritis score and hind paw thickness in mice. The body weight of the CIA mouse was significantly increased by TPLA treatment. TPLA improved the CIA-induced histopathological changes in the hind paw and joint tissues from the mice. TPLA inhibited the bone loss and alleviated bone destruction in CIA mouse model. TPLA altered the macrophage phenotype from M1 macrophages into M2 in CIA mice. TPLA suppressed the levels of inflammatory markers both in the serum and joint tissues of the CIA mice. TPLA mitigated RA development by suppressing inflammatory reaction through the inhibition of M1 microphage polarization.

NLRP3 inflammasome and its role in autoimmune diseases: A promising therapeutic target

The NOD-like receptor protein 3 (NLRP3) inflammasome is a protein complex that regulates innate immune responses by activating caspase-1 and the inflammatory cytokines IL-1β and IL-18. Numerous studies have highlighted its crucial role in the pathogenesis and development of inflammatory bowel disease, rheumatoid arthritis, systemic lupus erythematosus, autoimmune thyroid diseases, and other autoimmune diseases. Therefore, investigating the underlying mechanisms of NLRP3 in disease and targeted drug therapies holds clinical significance. This review summarizes the structure, assembly, and activation mechanisms of the NLRP3 inflammasome, focusing on its role and involvement in various autoimmune diseases. This review also identifies studies where the involvement of the NLRP3 inflammasome in the disease mechanism within the same disease appears contradictory, as well as differences in NLRP3-related gene polymorphisms among different ethnic groups. Additionally, the latest therapeutic advances in targeting the NLRP3 inflammasome for autoimmune diseases are outlined, and novel clinical perspectives are discussed. Conclusively, this review provides a consolidated source of information on the NLRP3 inflammasome and may guide future research efforts that have the potential to positively impact patient outcomes.

Neutrophil Extracellular Traps Induce Pyroptosis of Rheumatoid Arthritis Fibroblast-Like Synoviocytes via the NF-κB/Caspase 3/GSDME Pathway

Rheumatoid arthritis (RA) is an enduring, progressive autoimmune disorder. Abnormal activation of fibroblast-like synoviocytes (FLSs) has been proposed as the initiating factor for inflammation of the synovium and bone destruction. Neutrophil extracellular traps (NETs), which are web-like structures composed of DNA, histones, and granule proteins, are involved in the development of RA in multiple aspects. Pyroptosis, gasdermin-mediated inflammatory programmed cell death, plays a vital function in the etiopathogenesis of RA. However, the exact mechanism underlying NETs-induced pyroptosis in FLSs of RA and its impact on cellular pathogenic behavior remain undefined. In this study, we demonstrated that gasdermin E (GSDME) expression was upregulated in RA plasma and synoviums, which was positively correlated with the elevated cell-free DNA (cfDNA) and citrullinated histone 3 (Cit H3) levels in the plasma. Additionally, in vitro experiments have shown that NETs triggered caspase 3/GSDME-mediated pyroptosis in RA-FLSs, characterized by decreased cell viability, cell membrane blebbing, and rupture, as well as increased levels of pyroptosis-related proteins and pro-inflammatory cytokines. Again, silencing GSDME significantly inhibited pyroptosis and suppressed the migration, invasion, and secretion of pro-inflammatory cytokines in RA-FLSs. Furthermore, we also found that the nuclear factor-kappa B (NF-κB) pathway, serving as an upstream mechanism, was involved in FLS pyroptosis. In conclusion, our investigation indicated that NETs could induce RA-FLS pyroptosis and facilitate phenotypic transformation through targeting the NF-κB/caspase 3/GSDME axis. This is the first to explore the crucial role of NETs-induced FLS pyroptosis in the progression of RA, providing novel targets for the clinical management of refractory RA.

YL-109 attenuates sepsis-associated multiple organ injury through inhibiting the ERK/AP-1 axis and pyroptosis by upregulating CHIP

Sepsis is a severe inflammatory disorder that can lead to life-threatening multiple organ injury. Lipopolysaccharide (LPS)-induced inflammation is the leading cause of multiple organ failure in sepsis. This study aimed to explore the effect of a novel agent, 2-(4-hydroxy-3-methoxyphenyl)-benzothiazole (YL-109), on LPS-induced multiple organ injury and the molecular mechanisms underlying these processes. The results showed that YL-109 protected against LPS-induced high mortality, cardiac dysfunction, pulmonary and intestinal injury through inhibiting the proinflammatory response, NLRP3 expression and pyroptosis-associated indicators in mouse tissues. YL-109 suppressed LPS-initiated cytokine release, pyroptosis and pyroptosis-related protein expression in HL-1, IEC-6 and MLE-12 cells, which was consistent with the results of the in vivo experiments. Mechanistically, YL-109 reduces phosphorylated ERK (extracellular signal-regulated kinase) levels and NF-κB activation, which are achieved through upregulating CHIP (carboxy terminus of Hsc70-interacting protein) expression, thereby inhibiting c-Jun and c-Fos activation as well as NLRP3 expression. As an E3 ligase, CHIP overexpression obviously promoted the degradation of phosphorylated ERK and inhibited the expression of NF-κB-mediated NLRP3 in cells stimulated with LPS. The protective effects of YL-109 against cardiac, pulmonary and intestinal damage, inflammation and pyroptosis caused by LPS were eliminated in CHIP knockout mice. Our results not only reveal the protective effect and molecular mechanism of YL-109 against LPS-mediated organs damage but also provide additional insights into the effect of CHIP on negatively regulating pyroptosis and inflammatory pathways.

Advanced application of carbohydrate-based micro/nanoparticles for rheumatoid arthritis

Rheumatoid arthritis (RA) is a kind of synovitis and progressive joint destruction disease. Dysregulated immune cell activation, inflammatory cytokine overproduction, and subsequent reactive oxidative species (ROS) production contribute to the RA process. Carbohydrates, including cellulose, chitosan, alginate and dextran, are among the most abundant and important biomolecules in nature and are widely used in biomedicine. Carbohydrate-based micro/nanoparticles(M/NPs) as functional excipients have the ability to improve the bioavailability, solubility and stability of numerous drugs used in RA therapy. For on-demand therapy, smart reactive M/NPs have been developed to respond to a variety of chemical and physical stimuli, including light, temperature, enzymes, pH and ROS, alternating their physical and macroscopic properties, resulting in innovative new drug delivery systems. In particular, advanced products with targeted dextran or hyaluronic acid are exploiting multiple beneficial properties at the same time. In addition to those that respond, there are promising new derivatives in development with microenvironment and chronotherapy effects. In this review, we provide an overview of these recent developments and an outlook on how this class of agents will further shape the landscape of drug delivery for RA treatment.

Macrophage polarization in rheumatoid arthritis: signaling pathways, metabolic reprogramming, and crosstalk with synovial fibroblasts

Rheumatoid arthritis (RA) is a chronic autoimmune disease characterized by persistent synovial inflammation and progressive joint destruction. Macrophages are key effector cells that play a central role in RA pathogenesis through their ability to polarize into distinct functional phenotypes. An imbalance favoring pro-inflammatory M1 macrophages over anti-inflammatory M2 macrophages disrupts immune homeostasis and exacerbates joint inflammation. Multiple signaling pathways, including Notch, JAK/STAT, NF-κb, and MAPK, regulate macrophage polarization towards the M1 phenotype in RA. Metabolic reprogramming also contributes to this process, with M1 macrophages prioritizing glycolysis while M2 macrophages utilize oxidative phosphorylation. Redressing this imbalance by modulating macrophage polarization and metabolic state represents a promising therapeutic strategy. Furthermore, complex bidirectional interactions exist between synovial macrophages and fibroblast-like synoviocytes (FLS), forming a self-perpetuating inflammatory loop. Macrophage-derived factors promote aggressive phenotypes in FLS, while FLS-secreted mediators contribute to aberrant macrophage activation. Elucidating the signaling networks governing macrophage polarization, metabolic adaptations, and crosstalk with FLS is crucial to developing targeted therapies that can restore immune homeostasis and mitigate joint pathology in RA.

Traditional Chinese medicine in regulating macrophage polarization in immune response of inflammatory diseases

ETHNOPHARMACOLOGICAL RELEVANCE

Numerous studies have demonstrated that various traditional Chinese medicines (TCMs) exhibit potent anti-inflammatory effects against inflammatory diseases mediated through macrophage polarization and metabolic reprogramming.

AIM OF THE STUDY

The objective of this review was to assess and consolidate the current understanding regarding the pathogenic mechanisms governing macrophage polarization in the context of regulating inflammatory diseases. We also summarize the mechanism action of various TCMs on the regulation of macrophage polarization, which may contribute to facilitate the development of natural anti-inflammatory drugs based on reshaping macrophage polarization.

MATERIALS AND METHODS

We conducted a comprehensive review of recently published articles, utilizing keywords such as "macrophage polarization" and "traditional Chinese medicines" in combination with "inflammation," as well as "macrophage polarization" and "inflammation" in conjunction with "natural products," and similar combinations, to search within PubMed and Google Scholar databases.

RESULTS

A total of 113 kinds of TCMs (including 62 components of TCMs, 27 TCMs as well as various types of extracts of TCMs and 24 Chinese prescriptions) was reported to exert anti-inflammatory effects through the regulation of key pathways of macrophage polarization and metabolic reprogramming.

CONCLUSIONS

In this review, we have analyzed studies concerning the involvement of macrophage polarization and metabolic reprogramming in inflammation therapy. TCMs has great advantages in regulating macrophage polarization in treating inflammatory diseases due to its multi-pathway and multi-target pharmacological action. This review may contribute to facilitate the development of natural anti-inflammatory drugs based on reshaping macrophage polarization.

Punicalagin promotes mincle-mediated phagocytosis of macrophages via the NF-κB and MAPK signaling pathways

Punicalagin (PUN) is a polyphenol derived from the pomegranate peel. It has been reported to have many beneficial effects, including anti-inflammatory, anti-oxidant, and anti-proliferation. However, the role of PUN in macrophage phagocytosis is currently unknown. In this study, we found that pre-treatment with PUN significantly enhanced phagocytosis by macrophages in a time- and dose-dependent manner in vitro. Moreover, KEGG enrichment analysis by RNA-sequencing showed that differentially expressed genes following PUN treatment were significantly enriched in phagocyte-related receptors, such as the C-type lectin receptor signaling pathway. Among the C-type lectin receptor family, Mincle (Clec4e) significantly increased at the mRNA and protein level after PUN treatment, as shown by qRT-PCR and western blotting. Small interfering RNA (siRNA) mediated knockdown of Mincle in macrophages resulted in down regulation of phagocytosis. Furthermore, western blotting showed that PUN treatment enhanced the phosphorylation of nuclear factor kappa-B (NF-κB) and mitogen-activated protein kinase (MAPK) in macrophages at the early stage. Mincle-mediated phagocytosis by PUN was inhibited by PDTC (a NF-κB inhibitor) and SB203580 (a p38 MAPK inhibitor). In addition, PUN pre-treatment enhanced phagocytosis by peritoneal and alveolar macrophages in vivo. After intraperitoneal injection of Escherichia coli (E.coli), the bacterial load of peritoneal lavage fluid and peripheral blood in PUN pre-treated mice decreased significantly. Similarly, the number of bacteria in the lung tissue significantly reduced after intranasal administration of Pseudomonas aeruginosa (PAO1). Taken together, our results reveal that PUN enhances bacterial clearance in mice by activating the NF-κB and MAPK pathways and upregulating C-type lectin receptor expression to enhance phagocytosis by macrophages.

The Impact of NLRP3 Inflammasome on Osteoblasts and Osteogenic Differentiation: A Literature Review

Osteoblasts (OBs), which are a crucial type of bone cells, derive from bone marrow mesenchymal stem cells (MSCs). Accumulating evidence suggests inflammatory cytokines can inhibit the differentiation and proliferation of OBs, as well as interfere with their ability to synthesize bone matrix, under inflammatory conditions. NLRP3 inflammasome is closely associated with cellular pyroptosis, which can lead to excessive release of pro-inflammatory cytokines, causing tissue damage and inflammatory responses, however, the comprehensive roles of NLRP3 inflammasome in OBs and their differentiation have not been fully elucidated, making targeting NLRP3 inflammasome approaches to treat diseases related to OBs uncertain. In this review, we provide a summary of NLRP3 inflammasome activation and its impact on OBs. We highlight the significant roles of NLRP3 inflammasome in regulating OBs differentiation and function. Furthermore, current available strategies to affect OBs function and osteogenic differentiation targeting NLRP3 inflammasome are listed and analyzed. Finally, through the prospective discussion, we seek to provide novel insights into the crucial role of NLRP3 inflammasome in diseases related to OBs and offer valuable information for devising treatment strategies.

Jianpi Antai formula prevents miscarriage by repressing M1 polarization of decidual macrophages through ubiquitination of NLRP3 mediated by MARCH7

ETHNOPHARMACOLOGICAL RELEVANCE

Jianpi Antai Formula (JAF) is an ancient formula from He's gynecology, which has been used clinically for more than 30 years and has significant therapeutic effects on spontaneous abortion (SA). Both macrophage polarization and NLRP3 inflammasome correlate with the occurrence of SA in women with recurrent or threatened miscarriage. Whether JAF prevent SA via mediating activation of decidual macrophage (dMφ) and ubiquitination-associated degradation of NLRP3 remains uncertain.

AIM OF THE STUDY

This study aimed to clarify the effects of JAF on pregnancy outcomes and dMφ polarization at the maternal-fetal interface in an SA mouse model, and use in vivo and invitro methods to explore whether JAF can inhibit M1 polarization of dMφ by up-regulating MARCH7-mediated NLRP3 ubiquitination, thereby preventing SA.

MATERIALS AND METHODS

The CBA/J × DBA/2 mating method was used to establish an SA model and the dMφs of SA mice were isolated and cultured. Th1-, Th2-, Th17- and Treg-related cytokine levels were evaluated using ELISA. qRT-PCR was used to detect the levels of M1/M2 macrophage-related cytokine mRNA in the decidua, and western blotting was used to detect the expression of NLRP3 inflammasome-related proteins in the decidua and placenta. The expression of M1/M2 markers of dMφ was detected using flow cytometry, ASC speck formation was observed using immunofluorescence, and the ubiquitination level of MARCH7-NLRP3 was detected using co-immunoprecipitation.

RESULTS

JAF increased the survival rate of fetuses and the levels of estradiol and progesterone in SA model mice. It also reduced the serum Th1 and Th17-associated cytokine levels and decidual M1 macrophage-associated cytokine levels, while elevating the M2 macrophages in SA mice. NLRP3, caspase-1, ASC, and IL-1β protein expression in the decidua and placenta were also reduced. si-MARCH7 transfection reversed the effect of JAF on inhibiting the formation of the NLRP3 inflammasome and the activation of macrophages in dMφs of SA mice.

CONCLUSION

JAF could effectively prevent and treat SA by repressing M1 polarization of dMφs through NLRP3 ubiquitination and pyroptosis inhibition, which were mediated by MARCH7.

Biomimetic nanoparticles for effective Celastrol delivery to targeted treatment of rheumatoid arthritis through the ROS-NF-κB inflammasome axis

Previous study has indicated that Celastrol (Cel) has various physiological and pharmacological effects, including antibacterial, antioxidant, pro-apoptotic, anticancer and anti-rheumatoid arthritis (RA) effects. However, low water solubility, low oral bioavailability, narrow treatment window, and high incidence of systemic adverse reactions still limit the further clinical application of Cel. Here, aiming at effectively overcome those shortcomings of Cel to boost its beneficial effects for treating RA, we developed the leukosome (LEUKO) coated biomimetic nanoparticles (NPs) for the targeted delivery of Cel to arthritis injury area in RA. LEUKO were synthesized using membrane proteins purified from activated J774 macrophage. LEUKO and Cel-loaded LEUKO (Cel@LEUKO) were characterized using dynamic light scattering and transmission electron microscopy. Our results demonstrated that Cel@LEUKO can inhibit the inflammatory response of lipopolysaccharide (LPS) induced mouse monocyte macrophage leukemia cells (RAW264.7 cells) and human rheumatoid arthritis synovial fibroblasts (MH7A) cells through the inhibition of reactive oxygen species (ROS)-NF-κB pathway. In addition, research has shown that LEUKO effectively targets and transports Cel to the inflammatory site of RA, increased drug concentration in affected areas, reduced systemic toxicity of Cel, and reduced clinical symptoms, inflammatory infiltration, bone erosion, and serum inflammatory factors in collagen-induced arthritis (CIA) rats.

Gallic Acid-Modified Polyethylenimine-Polypropylene Carbonate-Polyethylenimine Nanoparticles: Synthesis, Characterization, and Anti-Periodontitis Evaluation

The aim of the research was to develop novel gallic acid (GA)-modified amphiphilic nanoparticles of polyethylenimine (PEI)-polypropylene carbonate (PPC)-PEI (PEPE) and comprehensively assess its properties as an antiperiodontitis nanoparticle targeting the Toll-like receptor (TLR). The first step is to evaluate the binding potential of GA to the core trigger receptors TLR2 and TLR4/MD2 for periodontitis using molecular docking techniques. Following this, we conducted NMR, transmission electron microscopy, and dynamic light scattering analyses on the synthesized PEPE nanoparticles. As the final step, we investigated the synthetic results and in vitro antiperiodontitis properties of GA-PEPE nanoparticles. The investigation revealed that GA exhibits potential for targeted binding to TLR2 and the TLR4/MD2 complex. Furthermore, we successfully developed 91.19 nm positively charged PEPE nanoparticles. Spectroscopic analysis indicated the successful synthesis of GA-modified PEPE. Additionally, CCK8 results demonstrated that GA modification significantly reduced the biotoxicity of PEPE. The in vitro antiperiodontitis properties assessment illustrated that 6.25 μM of GA-PEPE nanoparticles significantly reduced the expression of pro-inflammatory factors TNF-α, IL-1β, and IL-6. The GA-PEPE nanoparticles, with their targeted TLR binding capabilities, were found to possess excellent biocompatibility and antiperiodontitis properties. GA-PEPE nanoparticles will provide highly innovative input into the development of anti- periodontitis nanoparticles.

Mechanisms of NLRP3 inflammasome in rheumatoid arthritis and osteoarthritis and the effects of traditional Chinese medicine

ETHNOPHARMACOLOGICAL RELEVANCE

It has been widely reported that various anti-rheumatic traditional Chinese medicines (TCMs) ameliorate rheumatoid arthritis (RA) and osteoarthritis (OA) through regulating the abnormal production, assembly, and activation of the NOD-like receptor thermal protein domain-associated protein 3 (NLRP3) inflammasome. These TCMs include monomers isolated from Chinese herbs, extracts of Chinese herbs, and Chinese medical formulae with a lengthy application history.

AIM OF THE STUDY

This review aimed to summarize and analyze the published articles about the NLRP3 inflammasome and its role in the pathogenesis of RA and OA. We also reviewed existing knowledge on the therapeutic mechanism of TCMs in RA and OA via the regulation of the NLRP3 inflammasome.

MATERIALS AND METHODS

We searched for relevant articles with the keywords "NLRP3 inflammasome", "traditional Chinese medicine," "Chinese herbal drugs," "rheumatoid arthritis," and "osteoarthritis." The information retrieval was conducted in medical Chinese and English databases from the date of construction to April 19, 2023, including PubMed, MEDLINE, Web of Science, Scopus, Ovid, China National Knowledge Infrastructure (CNKI), Chinese Biomedicine Literature Database (CBM), Chinese Science and Technology Periodicals Database (VIP), and China Online Journals (COJ).

RESULTS

According to retrieval results, 35 TCMs have been demonstrated to relieve RA by targeting the NLRP3 inflammasome, including six traditional Chinese prescriptions, seven extracts of Chinese herbs, and 22 monomers extracted from traditional Chinese herbs and formulae. Additionally, 23 TCMs have shown anti-OA effects with abilities to modulate the NLRP3 inflammasome, including five traditional Chinese prescriptions, one extract of Chinese herbs, and 17 monomers from Chinese herbs.

CONCLUSIONS

We summarized mechanism research about the pivotal roles of the NLRP3 inflammasome in the pathogenesis of RA and OA. Moreover, a review of TCMs with targets of the NLRP3 inflammasome in RA and OA treatment was also conducted. Our work is conducive to a better application of TCMs in complementary and alternative therapies in RA and OA.

Immunomodulatory effects of curcumin on macrophage polarization in rheumatoid arthritis

Rheumatoid arthritis (RA) is a systemic autoimmune disease characterized by synovial inflammation, cartilage destruction, pannus formation and bone erosion. Various immune cells, including macrophages, are involved in RA pathogenesis. The heterogeneity and plasticity of macrophages render them pivotal regulators of both the induction and resolution of the inflammatory response. Predominantly, two different phenotypes of macrophages have been identified: classically activated M1 macrophages exacerbate inflammation via the production of cytokines, chemokines and other inflammatory mediators, while alternatively activated M2 macrophages inhibit inflammation and facilitate tissue repair. An imbalance in the M1/M2 macrophage ratio is critical during the initiation and progression of RA. Macrophage polarization is modulated by various transcription factors, epigenetic elements and metabolic reprogramming. Curcumin, an active component of turmeric, exhibits potent immunomodulatory effects and is administered in the treatment of multiple autoimmune diseases, including RA. The regulation of macrophage polarization and subsequent cytokine production as well as macrophage migration is involved in the mechanisms underlying the therapeutic effect of curcumin on RA. In this review, we summarize the underlying mechanisms by which curcumin modulates macrophage function and polarization in the context of RA to provide evidence for the clinical application of curcumin in RA treatment.

Modulation of SEMA4D-modified titanium surface on M2 macrophage polarization via activation of Rho/ROCK-mediated lactate release of endothelial cells: In vitro and in vivo

SEMA4D-modified titanium surfaces can indirectly regulate macrophages through endothelial cells to achieve an anti-inflammatory effect, which is beneficial for healing soft tissues around the gingival abutment. However, the mechanism of surface-induced cellular phenotypic changes in SEMA4D-modified titanium has not yet been elucidated. SEMA4D activates the RhoA signaling pathway in endothelial cells, which coordinates metabolism and cytoskeletal remodeling. This study hypothesized that endothelial cells inoculated on SEMA4D-modified titanium surfaces can direct M2 polarization of macrophages via metabolites. An indirect co-culture model of endothelial cells and macrophages was constructed in vitro, and specific inhibitors were employed. Subsequently, endothelial cell adhesion and migration, metabolic changes, Rho/ROCK1 expression, and inflammatory expression of macrophages were assessed via immunofluorescence microscopy, specific kits, qRT-PCR, and Western blotting. Moreover, an in vivo rat bilateral maxillary implant model was constructed to evaluate the soft tissue healing effect. The in vitro experiments showed that the SEMA4D group had stronger endothelial cell adhesion and migration, increased Rho/ROCK1 expression, and enhanced release of lactate. Additionally, decreased macrophage inflammatory expression was observed. In contrast, the inhibitor group partially suppressed lactate metabolism and motility, whereas increased inflammatory expression. The in vivo analyses indicated that the SEMA4D group had faster and better angiogenic and anti-inflammatory effects, especially in the early stage. In conclusion, via the Rho/ROCK1 signaling pathway, the SEMA4D-modified titanium surface promotes endothelial cell adhesion and migration and lactic acid release, then the paracrine lactic acid promotes the polarization of macrophages to M2, thus obtaining the dual effects of angiogenesis and anti-inflammation.

Knockdown of angiopoietin-like 4 suppresses sepsis-induced acute lung injury by blocking the NF-κB pathway activation and hindering macrophage M1 polarization and pyroptosis

OBJECTIVE

Sepsis-induced acute lung injury (ALI) is a life-threatening disease. Macrophage pyroptosis has been reported to exert function in ALI. We aimed to investigate the mechanisms of ANGPTL4-mediated cell pyroptosis in sepsis-induced ALI, thus providing new insights into the pathogenesis and prevention and treatment measures of sepsis-induced ALI.

METHODS

In vivo animal models and in vitro cell models were established by cecal ligation and puncture (CLP) method and lipopolysaccharide-induced macrophages RAW264.7. ANGPTL4 was silenced in CLP mice or macrophages, followed by the determination of ANGPTL4 expression in bronchoalveolar lavage fluid (BALF) or macrophages. Lung histopathology was observed by H&E staining, with pathological injury scores evaluated and lung wet and dry weight ratio recorded. M1/M2 macrophage marker levels (iNOS/CD86/Arg1), inflammatory factor (TNF-α/IL-6/IL-1β/iNOS) expression in BALF, cell death and pyroptosis, NLRP3 inflammasome, cell pyroptosis-related protein (NLRP3/Cleaved-caspase-1/caspase-1/GSDMD-N) levels, NF-κB pathway activation were assessed by RT-qPCR/ELISA/flow cytometry/Western blot, respectively.

RESULTS

ANGPTL4 was highly expressed in mice with sepsis-induced ALI, and ANGPTL4 silencing ameliorated sepsis-induced ALI in mice. In vivo, ANGPTL4 silencing repressed M1 macrophage polarization and macrophage pyroptosis in mice with sepsis-induced ALI. In vitro, ANGPTL4 knockout impeded LPS-induced activation and pyroptosis of M1 macrophages and hindered LPS-induced activation of the NF-κB pathway in macrophages.

CONCLUSION

Knockdown of ANGPTL4 blocks the NF-κB pathway activation, hinders macrophage M1 polarization and pyroptosis, thereby suppressing sepsis-induced ALI.

The Role of Innate Immunity in Osteoarthritis and the Connotation of "Immune-joint" Axis: A Narrative Review

Osteoarthritis (OA) is a degenerative disease that results in constriction of the joint space due to the gradual deterioration of cartilage, alterations in subchondral bone, and synovial membrane. Recently, scientists have found that OA involves lesions in the whole joint, in addition to joint wear and tear and cartilage damage. Osteoarthritis is often accompanied by a subclinical form of synovitis, which is a chronic, relatively low-grade inflammatory response mainly mediated by the innate immune system. The "immune-joint" axis refers to an interaction of an innate immune response with joint inflammation and the whole joint range. Previous studies have underestimated the role of the immune-joint axis in OA, and there is no related research. For this reason, this review aimed to evaluate the existing evidence on the influence of innate immune mechanisms on the pathogenesis of OA. The innate immune system is the body's first line of defense. When the innate immune system is triggered, it instantly activates the downstream inflammatory signal pathway, causing an inflammatory response, while also promoting immune cells to invade joint synovial tissue and accelerate the progression of OA. We have proposed the concept of the "immune-joint" axis and explored it from two aspects of Traditional Chinese Medicine (TCM) theory and modern medical research, such as the innate immunity and OA, macrophages and OA, complement and OA, and other cells and OA, to enrich the scientific connotation of the "immune-joint" axis.

Par3L, a polarity protein, promotes M1 macrophage polarization and aggravates atherosclerosis in mice via p65 and ERK activation

Proinflammatory M1 macrophages are critical for the progression of atherosclerosis. The Par3-like protein (Par3L) is a homolog of the Par3 family involved in cell polarity establishment. Par3L has been shown to maintain the stemness of mammary stem cells and promote the survival of colorectal cancer cells. In this study, we investigated the roles of the polar protein Par3L in M1 macrophage polarization and atherosclerosis. To induce atherosclerosis, Apoe-/- mice were fed with an atherosclerotic Western diet for 8 or 16 weeks. We showed that Par3L expression was significantly increased in human and mouse atherosclerotic plaques. In primary mouse macrophages, oxidized low-density lipoprotein (oxLDL, 50 μg/mL) time-dependently increased Par3L expression. In Apoe-/- mice, adenovirus-mediated Par3L overexpression aggravated atherosclerotic plaque formation accompanied by increased M1 macrophages in atherosclerotic plaques and bone marrow. In mouse bone marrow-derived macrophages (BMDMs) or peritoneal macrophages (PMs), we revealed that Par3L overexpression promoted LPS and IFNγ-induced M1 macrophage polarization by activating p65 and extracellular signal-regulated kinase (ERK) rather than p38 and JNK signaling. Our results uncover a previously unidentified role for the polarity protein Par3L in aggravating atherosclerosis and favoring M1 macrophage polarization, suggesting that Par3L may serve as a potential therapeutic target for atherosclerosis.

Treponema pallidum Promotes the Polarization of M2 Subtype Macrophages to M1 Subtype Mediating the Apoptosis and Inhibiting the Angiogenesis of Human Umbilical Vein Endothelial Cells

M2 macrophages were related to local immune homeostasis and maternal-fetal tolerance in normal pregnancy; whether M2 macrophages can respond to the stimulation of Treponema pallidum to mediate placental vascular inflammation injury is unclear. In this study, M2 macrophages were constructed to investigate the impact of T. pallidum on macrophage polarization and the underlying signaling pathway involved in this process, and the influence of macrophage polarization triggered by T. pallidum on the apoptosis and angiogenesis of human umbilical vein endothelial cells (HUVEC) was also explored. The results showed that M2 macrophage markers (CD206 and PPARγ) and anti-inflammatory factors (TGFβ and CCL18) were decreased, while M1 macrophage marker CD80 and inflammatory cytokines (IL1β and TNFα) were increased when M2 macrophages were treated with T. pallidum, indicating that T. pallidum promoted the polarization of M2 subtype macrophages to the M1 subtype. Moreover, T. pallidum-induced M1 macrophage polarization was found to be significantly correlated with the activation of Janus kinase 1 (JAK1) and signal transducer and activator of transcription 1 (STAT1). In addition, T. pallidum-induced M1 macrophages were found to promote apoptosis and inhibit the angiogenesis of HUVECs, and JAK1 or STAT1 inhibitors could weaken the apoptosis rate and promote the angiogenesis of HUVECs. These findings revealed that T. pallidum promoted the polarization of M2 macrophages to the M1 subtype through the JAK1-STAT1 signal pathway mediating the apoptosis and inhibiting angiogenesis of HUVECs, which may provide a possible mechanism for T. pallidum-induced adverse pregnancy outcomes.

Single-cell histone chaperones patterns guide intercellular communication of tumor microenvironment that contribute to breast cancer metastases

BACKGROUND

Histone chaperones (HCs) are crucial for governing genome stability and gene expression in multiple cancers. However, the functioning of HCs in the tumor microenvironment (TME) is still not clearly understood.

METHODS

Self-tested single-cell RNA-seq data derived from 6 breast cancer (BC) patients with brain and liver metastases were reanalyzed by nonnegative matrix factorization (NMF) algorithm for 36 HCs. TME subclusters were observed with BC and immunotherapy public cohorts to assess their prognosis and immune response. The biological effect of HSPA8, one of the HCs, was verified by transwell assay and wound-healing assays.

RESULTS

Cells including fibroblasts, macrophages, B cells, and T cells, were classified into various subclusters based on marker genes. Additionally, it showed that HCs might be strongly associated with biological and clinical features of BC metastases, along with the pseudotime trajectory of each TME cell type. Besides, the results of bulk-seq analysis revealed that TME cell subclusters mediated by HCs distinguished significant prognostic value for BC patients and were relevant to patients' immunotherapy responses, especially for B cells and macrophages. In particular, CellChat analysis exhibited that HCs-related TME cell subclusters revealed extensive and diverse interactions with malignant cells. Finally, transwell and wound-healing assays exhibited that HSPA8 deficiency inhibited BC cell migration and invasion.

CONCLUSIONS

Collectively, our study first dissected HCs-guided intercellular communication of TME that contribute to BC metastases.

Puerarin prevents sepsis-associated encephalopathy by regulating the AKT1 pathway in microglia

BACKGROUND

Previous studies have reported that puerarin possesses cardioprotective, vasodilatory, anti-inflammatory, anti-apoptotic, and hypoglycemic properties. However, the impact of puerarin on sepsis-associated encephalopathy (SAE) remains unexplored. In this study, we explored whether puerarin can modulate microglia-mediated neuroinflammation for the treatment of SAE and delved into the underlying mechanisms.

METHODS

We established a murine model of SAE through intraperitoneal injection of lipopolysaccharide (LPS). The puerarin treatment group received pretreatment with puerarin. For in vitro experiments, BV2 cells were pre-incubated with puerarin for 2 h before LPS exposure. We employed network pharmacology, the Morris Water Maze (MWM) test, Novel Object Recognition (NOR) test, immunofluorescence staining, enzyme-linked immunosorbent assay (ELISA), Western blotting, and quantitative real-time PCR (qRT-PCR) to elucidate the molecular mechanism of underlying puerarin's effects in SAE treatment.

RESULTS

Our findings demonstrate that puerarin significantly reduced the production of inflammatory cytokines (TNF-α and IL-6) in the peripheral blood of LPS-treated mice. Moreover, puerarin treatment markedly ameliorated sepsis-associated cognitive impairment. Puerarin also exhibited inhibitory effects on the release of TNF-α and IL-6 from microglia, thereby preventing hippocampal neuronal cell death. Network pharmacology analysis identified AKT1 as a potential therapeutic target for puerarin in SAE treatment. Subsequently, we validated these results in both in vitro and in vitro experiments. Our study conclusively demonstrated that puerarin reduced LPS-induced phosphorylation of AKT1, with the AKT activator SC79 reversing puerarin's anti-inflammatory effects through the activation of the AKT1 signaling pathway.

CONCLUSION

Puerarin exerts an anti-neuroinflammatory effect against SAE by modulating the AKT1 pathway in microglia.

Phenylalanine diminishes M1 macrophage inflammation

Emerging evidence suggests that amino acids dictate the effector functions of immune cells; however, whether and how phenylalanine (Phe) orchestrates the polarization of macrophages is not understood. Here, we determined that Phe attenuated lipopolysaccharide (LPS) and P. multocida serotype A strain CQ2 (PmCQ2) infection-induced inflammation in vivo. Furthermore, we demonstrated that Phe inhibited the production of interleukin (IL)-1β and tumor necrosis factor (TNF)-α in proinflammatory (M1) macrophages. Phe reprogrammed the transcriptomic and metabolic profiles and enhanced oxidative phosphorylation in M1 macrophages, which reduced the activation of caspase-1. Notably, the valine-succinyl-CoA axis played a critical role in Phe-mediated inhibition of IL-1β production in M1 macrophages. Taken together, our findings suggest that manipulating the valine-succinyl-CoA axis provides a potential target for preventing and/or treating macrophage-related diseases.

Platelet-derived microparticles stimulated by anti-β2GPI/β2GPI complexes induce pyroptosis of endothelial cells in antiphospholipid syndrome

Platelet microparticles (PMPs) are vesicles that are released by platelets into the extracellular space and play a role in antiphospholipid antibody syndromes. PMPs have recently been recognized as a new and viable cell. There is growing evidence that the anti-β₂ glycoprotein (GPI)/β₂GPI complex is associated with aberrant activation of PMPs. Although studies suggest that aberrant activation of PMPs may lead to inflammatory necrosis of endothelial cells, the underlying mechanisms remain unclear. We found that although the difference in the number of PMPs was not statistically significant, NLR family pyrin domain containing 3 (NLRP3) within PMPs was increased during stimulation of anti-β₂GPI/β₂GPI complexes. Furthermore, we demonstrated that anti-β₂GPI/β₂GPI complex-induced PMPs effectively stimulated endothelial cell pyroptosis via the NLRP3/nuclear factor (NF)-κB/gasdermin D (GSDMD) signaling pathway as well as the NLRP3/Caspase-1 signaling pathway. Additionally, inhibition of NLRP3 expression in PMPs effectively reduced the inflammatory response and pyroptosis in endothelial cells. Our data suggest that PMPs aberrantly activated by anti-β₂GPI/β₂GPI complexes play a vital role in endothelial cell pyroptosis, and these studies provide major insights into the mechanisms of thrombosis during the treatment of antiphospholipid antibody syndrome.

Local administration of liposomal-based Plekhf1 gene therapy attenuates pulmonary fibrosis by modulating macrophage polarization

Idiopathic pulmonary fibrosis (IPF) is a fatal interstitial lung disease with limited therapeutic options. Macrophages, particularly alternatively activated macrophages (M2), have been recognized to contribute to the pathogenesis of pulmonary fibrosis. Therefore, targeting macrophages might be a viable therapeutic strategy for IPF. Herein, we report a potential nanomedicine-based gene therapy for IPF by modulating macrophage M2 activation. In this study, we illustrated that the levels of pleckstrin homology and FYVE domain containing 1 (Plekhf1) were increased in the lungs originating from IPF patients and PF mice. Further functionality studies identified the pivotal role of Plekhf1 in macrophage M2 activation. Mechanistically, Plekhf1 was upregulated by IL-4/IL-13 stimulation, after which Plekhf1 enhanced PI3K/Akt signaling to promote the macrophage M2 program and exacerbate pulmonary fibrosis. Therefore, intratracheal administration of Plekhf1 siRNA-loaded liposomes could effectively suppress the expression of Plekhf1 in the lungs and notably protect mice against BLM-induced lung injury and fibrosis, concomitant with a significant reduction in M2 macrophage accumulation in the lungs. In conclusion, Plekhf1 may play a crucial role in the pathogenesis of pulmonary fibrosis, and Plekhf1 siRNA-loaded liposomes might be a promising therapeutic approach against pulmonary fibrosis.

Pmepa1 knockdown alleviates SpA-induced pyroptosis and osteogenic differentiation inhibition of hBMSCs via p38MAPK/NLRP3 axis

BACKGROUND

Osteomyelitis is a refractory bone infectious disease, which usually results in progressive bone destruction and bone loss. The invasion of pathogens and subsequent inflammatory response could damage bone marrow mesenchymal stem cells (BMSCs) and inhibit osteogenic differentiation, and finally aggravate uncontrolled bone remodeling in osteomyelitis by affecting bone formation. Exploring the mechanisms of BMSCs injury and osteogenic differentiation inhibition may would help us to find potential therapeutic targets.

METHOD

Firstly, staphylococcal protein A (SpA)-treated human bone marrow mesenchymal stem cells (hBMSCs) were used to construct cell models of osteomyelitis. Secondly, transcriptome sequencing was performed to screen differentially expressed genes and then verified the expression of target genes. Next, in vitro experiments were conducted to explore the functions and mechanisms of prostate transmembrane protein androgen induced 1 (Pmepa1) in SpA-treated hBMSCs. Finally, the rat model of osteomyelitis was established to provide an auxiliary validation of the in vitro experimental results.

RESULTS

We found that SpA treatment induced inflammatory injury and inhibited osteogenic differentiation in hBMSCs, then the transcriptome sequencing and further detection results showed that Pmepa1 was significantly upregulated in this process. Functionally, Pmepa1 knockdown alleviated inflammatory injury and promoted osteogenic differentiation in SpA-treated hBMSCs. Among them, it was demonstrated that Pmepa1 knockdown exerted cytoprotective effects by alleviating pyroptosis of SpA-infected hBMSCs. Furthermore, recovery experiments revealed that Pmepa1 knockdown reversed SpA-mediated adverse effects by downregulating the p38MAPK/NLRP3 axis. Finally, the detection results of rat femoral osteomyelitis showed that the expression of Pmepa1 was up-regulated, and the expression trends of other indicators including p38MAPK, NLRP3, and caspase-1 were also consistent with the in vitro model.

CONCLUSION

Pmepa1 knockdown alleviates SpA-induced pyroptosis and inhibition of osteogenic differentiation in hBMSCs by downregulating p38MAPK/NLRP3 signaling axis. Modulating the expression of Pmepa1 may be a potential strategy to ameliorate osteomyelitis.

A novel drug combination of Tofacitinib and Iguratimod alleviates rheumatoid arthritis and secondary osteoporosis

BACKGROUND

The inadequate response of some patients with rheumatoid arthritis (RA) to current therapies is an issue that needs to be addressed. Patients with refractory RA (RRA) are often accompanied by high Tumor necrosis factor (TNF) expression. We evaluated the synergistic therapeutic effects of the combination of Iguratimod (IGU) and Tofacitinib (TOF) on RRA and secondary osteoporosis.

METHODS

Pathological changes in the ankle joints of collagen-induced arthritis (CIA) + TNF model rats were assessed using hematoxylin and eosin (HE) staining. Immunohistochemistry (IHC) and immunofluorescence (IF) were used to evaluate pyroptosis-related protein levels in the synovial tissues. Moreover, the knee joint was investigated by performing HE staining, IHC, and micro-computed tomography. Furthermore, in vitro, western blotting and enzyme-linked immunosorbent assay (ELISA) were performed to detect the effects of TOF and IGU on TNF-α-induced pyroptosis in fibroblast-like synoviocytes of RA.

RESULTS

After treatment with TOF and/or IGU, the arthritis scores, inflammatory cell infiltration in synovial tissues, and levels of interleukin (IL)-18, IL-1β, and IL-6 in the plasma were remarkably increased in the CIA + TNF model and dramatically decreased in the combination group. The expression of pyroptosis-related proteins was significantly lower in the combination group than in the CIA + TNF group, and a consistent trend was observed in vitro. Bone destruction was significantly alleviated, and the bone turnover rate was remarkably increased in the combination group compared to that in the CIA + TNF model.

CONCLUSION

TOF + IGU alleviated the severity of RRA in the CIA + TNF rat model, relieving joint inflammation, reducing bone erosion, and suppressing pyroptosis. The combined application of TOF and IGU may have a superimposed therapeutic effect on RRA and secondary osteoporotic bone remodeling.

Mitochondrion-NLRP3 inflammasome activation in macrophages: A novel mechanism of the anti-inflammatory effect of Notopterygium in rheumatoid arthritis treatment

OBJECTIVE

The mechanism by which Notopterygium (NE) regulates the nucleotide-binding, oligomerization domain (NOD)-like receptor family and pyrin domain-containing 3 (NLRP3) inflammasome to treat rheumatoid arthritis (RA) was investigated to reveal the scientific implications of NE in RA treatment.

METHODS

Adjuvant arthritis (AA) rats were replicated. After NE intervention, the anti-inflammatory efficacy of NE in vivo was determined. The mechanism of NE in RA treatment was predicted by network pharmacology, and the key target for further experiments was found through the analysis of Kyoto Encyclopedia of Genes and Genomes (KEGG). The effect of NE on the NLRP3 inflammasome in AA rats was verified. Furthermore, with the induction of inflammation in RAW264.7 cells by lipopolysaccharide (LPS), several techniques, such as Griess assay, enzyme linked immunosorbent assays, electron microscopy, and fluorescence probe technology, were used to investigate the anti-inflammatory and related mechanisms of NE in RA treatment.

RESULTS

NE could inhibit inflammation in AA rats. KEGG results showed that NLRP3 participated in the top three pathways of NE in RA treatment. Through Western blotting and immunofluorescence assays, this study demonstrated that NE can regulate NLRP3, pro-Caspase-1, Caspase-1, and CD11b in the ankle joint of AA rats. NE may significantly reduce the LPS-induced inflammatory response of RAW264.7 cells by alleviating mitochondrial damage, reducing the number of mitochondrial deoxyribonucleic Acid and mitochondrial reactive oxygen species, inhibiting NLRP3 inflammasome activation.

CONCLUSION

The anti-inflammatory and antirheumatic effect of NE may involve regulating NLRP3 inflammasome activation through mitochondria. NLRP3 is probably the key target molecule of NE in the treatment of RA.

Arecoline hydrobromide suppresses PI3K/AKT pathway in rheumatoid arthritis synovial fibroblasts and relieves collagen-induced arthritis in mice

OBJECTIVE

This study investigated the effectiveness of arecoline hydrobromide (AH) on the functions of rheumatoid arthritis fibroblast-like synoviocytes (RA-FLSs) and collagen-induced arthritis (CIA) mice.

METHODS

Immunofluorescence was used to identify RA-FLSs. Cell Counting Kit-8 (CCK-8) was used to determine the viability of RA-FLSs and the half maximal inhibitory concentration (IC50) of AH. The 5-ethynyl-2'-deoxyuridine (EdU) assay was used to detect DNA replication in RA-FLSs. Cell cycle and apoptosis were examined by flow cytometry. Migration and invasion, as well as wound healing assays, were employed to determine cell migration and invasion ability. Proteins and mRNA expression levels were investigated using Western blot, quantitative real-time PCR (RT-qPCR), and immunofluorescence. The CIA mice model was used to assess the effect of AH in vivo. RNA-sequencing (RNA-seq) was used to find the potential signaling pathways of AH against RA, and Western blot was used to verify the key signaling pathway of AH on RA-FLSs. Network pharmacology and molecular docking were used to predict drug targets.

RESULTS

AH inhibited the proliferation and DNA replication of RA-FLSs, promoted cell cycle arrest by reducing the levels of cyclin-dependent kinase 1 (CDK1), cyclin A2, and cyclin B1, promoted apoptosis by suppressing B-cell lymphoma-2 (Bcl-2) expression, and suppressed migration and invasion by inhibiting vimentin expression in RA-FLSs. AH was also effective in relieving arthritis in vivo. RNA sequencing analyses suggested that AH inhibited the phosphoinositide 3-kinase (PI3K)/protein kinase B (AKT) pathway in RA-FLSs, which was also confirmed in Western blot analysis. Furthermore, network pharmacology and molecular docking suggested that F2, MAPK14, SRC, AKT1, and CTSK might be the direct targets of AH.

CONCLUSION

AH can modulate the pathological process of RA-FLSs by blocking the PI3K/AKT pathway and relieve CIA in mice, making it a potential new small molecule candidate.

New Potentiality of Bioactive Substances: Regulating the NLRP3 Inflammasome in Autoimmune Diseases

The NOD-like receptor family pyrin domain-containing 3 (NLRP3) inflammasome is an essential component of the human innate immune system, and is closely associated with adaptive immunity. In most cases, the activation of the NLRP3 inflammasome requires priming and activating, which are influenced by various ion flux signals and regulated by various enzymes. Aberrant functions of intracellular NLRP3 inflammasomes promote the occurrence and development of autoimmune diseases, with the majority of studies currently focused on rheumatoid arthritis, systemic lupus erythematosus and systemic sclerosis. In recent years, a number of bioactive substances have shown new potentiality for regulating the NLRP3 inflammasome in autoimmune diseases. This review provides a concise overview of the composition, functions, and regulation of the NLRP3 inflammasome. Additionally, we focus on the newly discovered bioactive substances for regulating the NLRP3 inflammasome in autoimmune diseases in the past three years.

Mechanistic and therapeutic insights into the function of NLRP3 inflammasome in sterile arthritis

The NLRP3 inflammasome, which belongs to the pyrin domain containing 3 family of NOD-like receptors, has a significant impact on both the innate and adaptive immune responses. Regulating host immune function and protecting against microbial invasion and cell damage, the NLRP3 inflammasome plays a crucial role. By triggering caspase-1, it facilitates the development of the inflammatory cytokines IL-1β and IL-18, and triggers cell pyroptosis, resulting in cell lysis and demise. Common sterile arthritis includes osteoarthritis (OA), rheumatoid arthritis (RA) and gouty arthritis (GA), all of which manifest as bone destruction and synovial inflammation in a complex inflammatory state, placing a significant medical burden on the families of patients and government agencies. In the past few years, there has been a growing interest in investigating the impact of cell pyroptosis on arthritis development, particularly the widespread occurrence of pyroptosis mediated by the NLRP3 inflammasome. The NLRP3 inflammasome's biological properties are briefly described in this review, along with the presentation of the fundamental processes of pyroptosis resulting from its activation. Furthermore, we provide a summary of the advancements made in studying the NLRP3 inflammasome in various forms of arthritis and enumerate the intervention approaches that target the NLRP3-mediated pyroptosis, either directly or indirectly. These discoveries lay the groundwork for future investigations on medications for arthritis, offering fresh approaches for the clinical identification and treatment of this condition.

Pyroptosis: the potential eye of the storm in adult-onset Still's disease

Pyroptosis, a form of programmed cell death with a high pro-inflammatory effect, causes cell lysis and leads to the secretion of countless interleukin-1β (IL-1β) and IL-18 cytokines, resulting in a subsequent extreme inflammatory response through the caspase-1-dependent pathway or caspase-1-independent pathway. Adult-onset Still's disease (AOSD) is a systemic inflammatory disease with extensive disease manifestations and severe complications such as macrophage activation syndrome, which is characterized by high-grade inflammation and cytokine storms regulated by IL-1β and IL-18. To date, the pathogenesis of AOSD is unclear, and the available therapy is unsatisfactory. As such, AOSD is still a challenging disease. In addition, the high inflammatory states and the increased expression of multiple pyroptosis markers in AOSD indicate that pyroptosis plays an important role in the pathogenesis of AOSD. Accordingly, this review summarizes the molecular mechanisms of pyroptosis and describes the potential role of pyroptosis in AOSD, the therapeutic practicalities of pyroptosis target drugs in AOSD, and the therapeutic blueprint of other pyroptosis target drugs.

Substance P promote macrophage M2 polarization to attenuate secondary lymphedema by regulating NF-kB/NLRP3 signaling pathway

Secondary lymphedema often occurs after filariasis, trauma, lymph node dissection and radiation therapy, which is manifested by infiltration of inflammatory cells and fibrosis formation in pathologically. Substance P is a widely used neuropeptide in the field of tissue repair, while the regenerative potential of the substance P has not been proven in the secondary lymphedema. In this study, animal model of secondary lymphedema was constructed by excising the skin and subcutaneous lymphatic network in the tail of mice, and the degree of swelling in the tail of mice was evaluated after 6 weeks under the treatment with substance P. Immunofluorescence staining was also performed to assess immune cell infiltration, subcutaneous fibrosis and lymphangiogenesis. The results revealed that substance P significantly alleviated post-surgical lymphedema in mice. Furthermore, we found that substance P promoted macrophages M2 polarization, a process associated with downregulation of the NF-kB/NLRP3 pathway. After application of disodium clodronate (macrophage scavenger, CLO), the positive effect of substance P in lymphedema is significantly inhibited. In vitro experiments, we further demonstrated the polarizing effect of substance P on bone marrow-derived macrophages (BMDMs), while substance P inhibited the activation of the NF-kB/NLRP3 pathway in BMDMs after the treatment of lipopolysaccharide (LPS). In addition, polarized macrophages were demonstrated to promote the proliferation, tube-forming and migratory functions of human lymphatic endothelial cells (hLEC). In conclusion, our study provides preliminary evidence that substance P alleviates secondary lymphedema by promoting macrophage M2 polarization, and this therapeutic effect may be associated with downregulation of the NF-kB/NLRP3 pathway.

Autophagy suppression facilitates macrophage M2 polarization via increased instability of NF-κB pathway in hepatocellular carcinoma

The tumor microenvironment is a highly heterogeneous circumstance composed of multiple components, while tumor-associated macrophages (TAMs) are major innate immune cells with highly plastic and are always educated by tumor cells to structure an advantageous pro-tumor immune microenvironment. Despite emerging evidence focalizing the role of autophagy in other immune cells, the regulatory mechanism of autophagy in macrophage polarization remains poorly understood. Herein, we demonstrated that hepatocellular carcinoma (HCC) cells educated macrophages toward M2-like phenotype polarization under the condition of coculture. Moreover, we observed that inhibition of macrophage autophagy promoted M2-like macrophage polarization, while the tendency was impeded when autophagy was motivated. Mechanistically, macrophage autophagy inhibition inactivates the NF-κB pathway by increasing the instability of TAB3 via ubiquitination degradation, which leads to the M2-like phenotype polarization of macrophages. Both immunohistochemistry staining using human HCC tissues and experiment in vivo verified autophagy inhibition is correlated with M2 macrophage polarization. Altogether, we illustrated that macrophage autophagy was involved in the process of HCC cells domesticating M2 macrophage polarization via the NF-κB pathway. These results provide a new target to interfere with the polarization of macrophages to M2-like phenotype during HCC progression.

Exosomes derived from LPS-preconditioned bone marrow-derived MSC modulate macrophage plasticity to promote allograft survival via the NF-κB/NLRP3 signaling pathway

OBJECTIVES

This study investigated whether exosomes from LPS pretreated bone marrow mesenchymal stem cells (LPS pre-MSCs) could prolong skin graft survival.

METHODS

The exosomes were isolated from the supernatant of MSCs pretreated with LPS. LPS pre-Exo and rapamycin were injected via the tail vein into C57BL/6 mice allografted with BALB/c skin; graft survival was observed and evaluated. The accumulation and polarization of macrophages were examined by immunohistochemistry. The differentiation of macrophages in the spleen was analyzed by flow cytometry. For in vitro, an inflammatory model was established. Specifically, bone marrow-derived macrophages (BMDMs) were isolated and cultured with LPS (100 ng/ml) for 3 h, and were further treated with LPS pre-Exo for 24 h or 48 h. The molecular signaling pathway responsible for modulating inflammation was examined by Western blotting. The expressions of downstream inflammatory cytokines were determined by Elisa, and the polarization of macrophages was analyzed by flow cytometry.

RESULTS

LPS pre-Exo could better ablate inflammation compared to untreated MSC-derived exosomes (BM-Exo). These loaded factors inhibited the expressions of inflammatory factors via a negative feedback mechanism. In vivo, LPS pre-Exo significantly attenuated inflammatory infiltration, thus improving the survival of allogeneic skin graft. Flow cytometric analysis of BMDMs showed that LPS pre-Exo were involved in the regulation of macrophage polarization and immune homeostasis during inflammation. Further investigation revealed that the NF-κB/NLRP3/procaspase-1/IL-1β signaling pathway played a key role in LPS pre-Exo-mediated regulation of macrophage polarization. Inhibiting NF-κB in BMDMs could abolish the LPS-induced activation of inflammatory pathways and the polarization of M1 macrophages while increasing the proportion of M2 cells.

CONCLUSION

LPS pre-Exo are able to switch the polarization of macrophages and enhance the resolution of inflammation. This type of exosomes provides an improved immunotherapeutic potential in prolonging graft survival.

Punicalagin alleviates the hyperproliferation of keratinocytes in psoriasis through inhibiting SKP2 expression

Psoriasis is a chronic inflammatory skin disorder characterized by abnormal keratinocytes proliferation and multiple immune cells infiltration in the dermis and epidermis. Although most psoriasis-related researches have been concentrated on the interleukin-23 (IL-23)/interleukin-17 (IL-17) axis, new data suggest that keratinocytes also play a pivotal role in psoriasis. Previously, we found that punicalagin (PUN), a bioactive ellagitannin extracted from Pericarpium Granati (the pericarpium of Punica granatum L.), exerts a therapeutic effect on psoriasis. However, the underlying mechanism, especially its potential modulatory effect on keratinocytes, remains obscure. Our study aims to reveal the potential regulatory effect and its underlying cellular mechanism of PUN on the hyperproliferation of keratinocytes. We used tumor necrosis factor α (TNF-α), IL-17A and interleukin-6 (IL-6) to induce abnormal proliferation of HaCaT cells (Human Keratinocytes Cells) in vitro. Then, we evaluated the effects of PUN through MTT assay, EdU staining and cell cycle detection. Finally, we explored the underlying cellular mechanisms of PUN via RNA-sequencing, WB in vitro and in vivo. Here, we found that PUN can directly and dose-dependently decrease TNF-α, IL-17A and IL-6-induced abnormal proliferation of HaCaT cells in vitro. Mechanically, PUN suppresses the hyperproliferation of keratinocytes through repressing S-phase kinase-associated protein 2 (SKP2) expression in vitro and in vivo. Moreover, overexpression of SKP2 can partly abolish PUN-mediated inhibition of aberrantly proliferative keratinocytes. These results illustrate that PUN can reduce the severity of psoriasis through directly repressing SKP2-mediated abnormal proliferation of keratinocytes, which gives new insight into the therapeutic mechanism of PUN on psoriasis. Moreover, these findings imply that PUN might be a promising drug candidate for the treatment of psoriasis.

Lonicerin alleviates the progression of experimental rheumatoid arthritis by downregulating M1 macrophages through the NF-κB signaling pathway

The present study aimed to evaluate anti-rheumatoid arthritis (RA) effect of Lonicerin (LON), a safe compound with anti-inflammatory and immunomodulatory properties. Nevertheless, the exact role of LON in RA remains elusive. In this test, the anti-RA effect of LON was evaluated in collagen-induced arthritis (CIA) mouse model. Relevant parameters were measured during the experiment; ankle tissue and serum were collected at the end of the experiment for radiology, histopathology, and inflammation analysis. ELISA, qRT-PCR, immunofluorescence, and western blot were used to explore the effect of LON on the polarization of macrophages and related signal pathways. It was discovered that LON treatment attenuated the disease progression of CIA mice with lower paw swelling, clinical score, mobility, and inflammatory response. LON treatment significantly decreased M1 marker levels in CIA mice and LPS/IFN-γ-induced RAW264.7 cells, while slightly increasing M2 marker levels in CIA mice and IL-4-induced RAW264.7 cells. Mechanistically, LON attenuated the activation of the NF-κB signaling pathway, which contributes to M1 macrophage polarization and inflammasome activation. In addition, LON inhibited NLRP3 inflammasome activation in M1 macrophages, thereby reducing inflammation by inhibiting IL-1β and IL-18 release. These results indicated that LON might exert anti-RA effects by regulating the polarization of M1/M2 macrophage, especially by inhibiting macrophage polarization toward M1.

Macrophage Polarization and the Regulation of Bone Immunity in Bone Homeostasis

Bone homeostasis is a dynamic equilibrium state of bone formation and absorption, ensuring skeletal development and repair. Bone immunity encompasses all aspects of the intersection between the skeletal and immune systems, including various signaling pathways, cytokines, and the crosstalk between immune cells and bone cells under both homeostatic and pathological conditions. Therefore, as key cell types in bone immunity, macrophages can polarize into classical pro-inflammatory M1 macrophages and alternative anti-inflammatory M2 macrophages under the influence of the body environment, participating in the regulation of bone metabolism and playing various roles in bone homeostasis. M1 macrophages can not only act as precursors of osteoclasts (OCs), differentiate into mature OCs, but also secrete pro-inflammatory cytokines to promote bone resorption; while M2 macrophages secrete osteogenic factors, stimulating the differentiation and mineralization of osteoblast precursors and mesenchymal stem cells (MSCs), and subsequently increase bone formation. Once the polarization of macrophages is imbalanced, the resulting immune dysregulation will cause inflammatory stimulation, and release a large amount of inflammatory factors affecting bone metabolism, leading to pathological conditions such as osteoporosis (OP), rheumatoid arthritis (RA), and steroid-induced femoral head necrosis (SANFH). In this review, we introduce the signaling pathways and related factors of macrophage polarization, as well as their relationships with immune factors, OB, OC, and MSC. We also discuss the roles of macrophage polarization and bone immunity in various diseases of bone homeostasis imbalance, as well as the factors regulating them, which may help to develop new methods for treating bone metabolic disorders.

Targeting macrophage M1 polarization suppression through PCAF inhibition alleviates autoimmune arthritis via synergistic NF-κB and H3K9Ac blockade

Sustained inflammatory invasion leads to joint damage and progressive disability in several autoimmune rheumatic diseases. In recent decades, targeting M1 macrophage polarization has been suggested as a promising therapeutic strategy for autoimmune arthritis. P300/CBP-associated factor (PCAF) is a histone acetyltransferase (HAT) that exhibits a strong positive relationship with the proinflammatory microenvironment. However, whether PCAF mediates M1 macrophage polarization remains poorly studied, and whether targeting PCAF can protect against autoimmune arthritis in vivo remains unclear. Commonly used drugs can cause serious side effects in patients because of their extensive and nonspecific distribution in the human body. One strategy for overcoming this challenge is to develop drug nanocarriers that target the drug to desirable regions and reduce the fraction of drug that reaches undesirable targets. In this study, we demonstrated that PCAF inhibition could effectively inhibit M1 polarization and alleviate arthritis in mice with collagen-induced arthritis (CIA) via synergistic NF-κB and H3K9Ac blockade. We further designed dextran sulfate (DS)-based nanoparticles (DSNPs) carrying garcinol (a PCAF inhibitor) to specifically target M1 macrophages in inflamed joints of the CIA mouse model via SR-A-SR-A ligand interactions. Compared to free garcinol, garcinol-loaded DSNPs selectively targeted M1 macrophages in inflamed joints and significantly improved therapeutic efficacy in vivo. In summary, our study indicates that targeted PCAF inhibition with nanoparticles might be a promising strategy for treating autoimmune arthritis via M1 macrophage polarization inhibition.

Prevention and treatment of inflammatory arthritis with traditional Chinese medicine: Underlying mechanisms based on cell and molecular targets

Inflammatory arthritis, primarily including rheumatoid arthritis, osteoarthritis and ankylosing spondylitis, is a group of chronic inflammatory diseases, whose general feature is joint dysfunction with chronic pain and eventually causes disability in older people. To date, both Western medicine and traditional Chinese medicine (TCM) have developed a variety of therapeutic methods for inflammatory arthritis and achieved excellent results. But there is still a long way to totally cure these diseases. TCM has been used to treat various joint diseases for thousands of years in Asia. In this review, we summarize clinical efficacies of TCM in inflammatory arthritis treatment after reviewing the results demonstrated in meta-analyses, systematic reviews, and clinical trials. We pioneered taking inflammatory arthritis-related cell targets of TCM as the entry point and further elaborated the molecular targets inside the cells of TCM, especially the signaling pathways. In addition, we also briefly discussed the relationship between gut microbiota and TCM and described the role of drug delivery systems for using TCM more accurately and safely. We provide updated and comprehensive insights into the clinical application of TCM for inflammatory arthritis treatment. We hope this review can guide and inspire researchers to further explore mechanisms of the anti-arthritis activity of TCM and make a great leap forward in comprehending the science of TCM.

IL-23/IL-17 immune axis mediates the imiquimod-induced psoriatic inflammation by activating ACT1/TRAF6/TAK1/NF-κB pathway in macrophages and keratinocytes

The interleukin-23 (IL-23)/IL-17 immune axis has been linked to the pathology of psoriasis, but how this axis contributes to skin inflammation in this disease remains unclear. We measured inflammatory cytokines associated with the IL-23/IL-17 immune axis in the serum of patients with psoriasis using enzyme-linked immunosorbent assays. Psoriasis was induced in male C57BL/6J mice using imiquimod (IMQ) cream, and animals received intraperitoneal injections of recombinant mouse anti-IL-23A or anti-IL-17A antibodies for 7 days. The potential effects of the IL-23/IL-17 immune axis on skin inflammation were assessed based on pathology scoring, hematoxylin-eosin staining of skin samples, and quantitation of inflammatory cytokines. Western blotting was used to evaluate levels of the following factors in skin: ACT1, TRAF6, TAK1, NF-κB, and pNF-κB. The serum of psoriasis patients showed elevated levels of several cytokines involved in the IL-23/IL-17 immune axis: IL-2, IL-4, IL-8, IL-12, IL-17, IL-22, IL-23, and interferon-γ. Levels of IL-23p19 and IL-17 were increased in serum and skin of IMQ-treated mice, while ACT1, TRAF6, TAK1, NF-κB, and pNF-κB were upregulated in the skin. A large proportion of NF-κB p65 localized in nucleus of involucrin+ cells in the epidermis and in F4/80+ cells of the dermis of psoriatic lesional skin. Treating these animals with anti-IL-23 or anti-IL-17 antibodies improved pathological score and immune imbalance, mitigated skin inflammation and downregulated ACT1, TRAF6, TAK1, NF-κB, and pNF-κB in skin. Our results suggest that skin inflammation mediated by the IL-23/IL-17 immune axis in psoriasis involves activation of the ACT1/TRAF6/TAK1/NF-κB pathway in keratinocytes and macrophage.

Koumine alleviates rheumatoid arthritis by regulating macrophage polarization

ETHNOPHARMACOLOGICAL RELEVANCE

The imbalance between M1-and M2-polarized macrophages is one of the major pathophysiological changes in RA. Therefore, targeted macrophage polarization may be an effective therapy for RA. Koumine, an alkaloid monomer with the highest content and low toxicity in Gelsemium elegans Benth., has the effect of treating RA by playing an immunomodulatory role by influencing various immune cells. However, whether koumine affects macrophage polarization in RA and the associated molecular mechanisms remain unknown.

AIM OF THE STUDY

To investigate the mechanism of the anti-RA effect of koumine on macrophage polarization.

MATERIALS AND METHODS

The effect of koumine on macrophage polarization was investigated in vivo and in vitro. We first explored the effects of koumine on AIA rats and detected the levels of M1/M2 macrophage polarization markers in the spleen by western blotting. Then, we explored the regulatory effect of koumine on M1/M2 macrophage polarization and the effect on the PI3K/AKT signaling pathway in vitro. Finally, we verified the effects of koumine on macrophage polarization in CIA mice.

RESULTS

We found that koumine alleviated symptoms, including relieving pain, reducing joint redness and swelling in AIA rats and restoring the M1/M2 macrophage balance in vivo. Interestingly, koumine had an inhibitory effect on both M1 and M2 macrophage polarization in vitro, but it had a stronger inhibitory effect on M1 macrophage. In a mixed polarization experiment, koumine mainly inhibited M1 macrophage polarization and had an inhibitory effect on the PI3K/AKT signaling pathway. Finally, we found that koumine had therapeutic effects on CIA mice, regulated macrophage polarization and inhibited the PI3K/AKT signaling pathway.

CONCLUSIONS

Our results reveal that koumine regulates macrophage polarization through the PI3K/AKT signaling pathway. This may be one of the important mechanisms of its anti-RA effect, which provides a theoretical and scientific basis for the possible clinical application of koumine.

Targeting different phenotypes of macrophages: A potential strategy for natural products to treat inflammatory bone and joint diseases

BACKGROUND

Macrophages, a key class of immune cells, have a dual role in inflammatory responses, switching between anti-inflammatory M2 and pro-inflammatory M1 subtypes depending on the specific environment. Greater numbers of M1 macrophages correlate with increased production of inflammatory chemicals, decreased osteogenic potential, and eventually bone and joint disorders. Therefore, reversing M1 macrophages polarization is advantageous for lowering inflammatory factors. To better treat inflammatory bone disorders in the future, it may be helpful to gain insight into the specific mechanisms and natural products that modulate macrophage polarization.

OBJECTIVE

This review examines the impact of programmed cell death and different cells in the bone microenvironment on macrophage polarization, as well as the effects of natural products on the various phenotypes of macrophages, in order to suggest some possibilities for the treatment of inflammatory osteoarthritic disorders.

METHODS

Using 'macrophage polarization,' 'M1 macrophage' 'M2 macrophage' 'osteoporosis,' 'osteonecrosis of femoral head,' 'osteolysis,' 'gouty arthritis,' 'collagen-induced arthritis,' 'freund's adjuvant-induced arthritis,' 'adjuvant arthritis,' and 'rheumatoid arthritis' as search terms, the relevant literature was searched using the PubMed, the Cochrane Library and Web of Science databases.

RESULTS

Targeting macrophages through different signaling pathways has become a key mechanism for the treatment of inflammatory bone and joint diseases, including HIF-1α, NF-κB, AKT/mTOR, JAK1/2-STAT1, NF-κB, JNK, ERK, p-38α/β, p38/MAPK, PI3K/AKT, AMPK, AMPK/Sirt1, STAT TLR4/NF-κB, TLR4/NLRP3, NAMPT pathway, as well as the programmed cell death autophagy, pyroptosis and ERS.

CONCLUSION

As a result of a search of databases, we have summarized the available experimental and clinical evidence supporting herbal products as potential treatment agents for inflammatory osteoarthropathy. In this paper, we outline the various modulatory effects of natural substances targeting macrophages in various diseases, which may provide insight into drug options and directions for future clinical trials. In spite of this, more mechanistic studies on natural substances, as well as pharmacological, toxicological, and clinical studies are required.

Bioactive Molecules against Rheumatoid Arthritis by Suppressing Pyroptosis

Rheumatoid arthritis is an inflammatory disease, and pyroptosis is a form of death associated with an inflammatory response. Pyroptosis, which occurs in synovial and osteoblastic cells, can exacerbate the development of rheumatoid arthritis. The inhibition of pyroptosis of these cells can, therefore, clearly be used as a therapeutic strategy against rheumatoid arthritis. Here, we have summarized the current status of progress in the treatment of rheumatoid arthritis by targeting cellular pyroptosis. We have identified seven compounds, including a cyclic RNA, a microRNA, a peptide, and a cytokine (protein), that may influence the progression of rheumatoid arthritis by regulating the initiation of pyroptosis. All of these compounds have been shown to have anti-rheumatoid effects in vitro and/or in vivo and have the potential to be developed as anti-rheumatoid agents. These findings may help to accelerate the development of anti-rheumatoid arthritis drugs.

Histone demethylases in the regulation of immunity and inflammation

Pathogens or danger signals trigger the immune response. Moderate immune response activation removes pathogens and avoids excessive inflammation and tissue damage. Histone demethylases (KDMs) regulate gene expression and play essential roles in numerous physiological processes by removing methyl groups from lysine residues on target proteins. Abnormal expression of KDMs is closely associated with the pathogenesis of various inflammatory diseases such as liver fibrosis, lung injury, and autoimmune diseases. Despite becoming exciting targets for diagnosing and treating these diseases, the role of these enzymes in the regulation of immune and inflammatory response is still unclear. Here, we review the underlying mechanisms through which KDMs regulate immune-related pathways and inflammatory responses. In addition, we also discuss the future applications of KDMs inhibitors in immune and inflammatory diseases.

Can pyroptosis be a new target in rheumatoid arthritis treatment?

Rheumatoid arthritis (RA) is a chronic systemic autoimmune disease of undefined etiology, with persistent synovial inflammation and destruction of articular cartilage and bone. Current clinical drugs for RA mainly include non-steroidal anti-inflammatory drugs (NSAIDs), glucocorticoids, disease modifying anti-rheumatic drugs (DMARDs) and so on, which can relieve patients' joint symptoms. If we want to have a complete cure for RA, there are still some limitations of these drugs. Therefore, we need to explore new mechanisms of RA to prevent and treat RA radically. Pyroptosis is a newly discovered programmed cell death (PCD) in recent years, which is characterized by the appearance of holes in cell membranes, cell swelling and rupture, and the release of intracellular pro-inflammatory factors into the extracellular space, resulting in a strong inflammatory response. The nature of pyroptosis is pro-inflammatory, and whether it is participating in the development of RA has attracted a wide interest among scholars. This review describes the discovery and mechanism of pyroptosis, the main therapeutic strategies for RA, and the role of pyroptosis in the mechanism of RA development. From the perspective of pyroptosis, the study of new mechanisms of RA may provide a potential target for the treatment of RA and the development of new drugs in the clinics.

CCL21/CCR7 axis as a therapeutic target for autoimmune diseases

Chemokine receptor 7 (CCR7) is a G protein-coupled receptor containing 7 transmembrane domains that is expressed on various cells, such as naive T/B cells, central memory T cells, regulatory T cells, immature/mature dendritic cells (DCs), natural killer cells, and a minority of tumor cells. Chemokine ligand 21 (CCL21) is the known high-affinity ligand that binds to CCR7 and drives cell migration in tissues. CCL21 is mainly produced by stromal cells and lymphatic endothelial cells, and its expression is significantly increased under inflammatory conditions. Genome-wide association studies (GWAS) have shown a strong association between CCL21/CCR7 axis and disease severity in patients with rheumatoid arthritis, sjogren's syndrome, systemic lupus erythematosus, polymyositis, ankylosing spondylitis, and asthma. Disrupting CCL21/CCR7 interaction with antibodies or inhibitors prevents the migration of CCR7-expressing immune and non-immune cells at the site of inflammation and reduces disease severity. This review emphasizes the importance of the CCL21 /CCR7 axis in autoimmune diseases and evaluates its potential as a novel therapeutic target for these conditions.