Role of NLRP3 Inflammasome in Rheumatoid Arthritis

Isolation, structure modification, and anti-rheumatoid arthritis activity of isopimarane-type diterpenoids from Orthosiphon aristatus

Orthosiphon aristatus is a well-known folkloric medicine and herb for Guangdong soup for the treatment of rheumatism in China. Eight isopimarane-type and migrated pimarane-type diterpenoids (1-8), including a new one with a rarely occurring α,β-unsaturated diketone C-ring, were isolated from O. aristatus. Their structures were determined by spectroscopic methods and quantum chemical calculations. Furthermore, the most abundant compound, orthosiphol K, was structurally modified by modern synthetic techniques to give seven new derivatives (9-15). The anti-rheumatoid arthritis activity of these diterpenoids were evaluated on a TNF-α induced MH7A human rheumatoid fibroblast-like synoviocyte model. Compound 10 showed the most potent activity among these compounds. Based on their inhibitory effects on the release levels of IL-1β, the preliminary structure-activity relationships were concluded. Furthermore, western blot analysis revealed that 10 could increase the expression of IκBα and decrease the expression of NF-κB p65, and the expression levels of COX-2 and NLRP3 proteins were consequently down-regulated.

Ganlu formula ethyl acetate extract (GLEE) blocked the development of experimental arthritis by inhibiting NLRP3 activation and reducing M1 type macrophage polarization

ETHNOPHARMACOLOGICAL RELEVANCE

The Tibetan medicine Ganlu Formula, as a classic prescription, is widely used across the Qinghai-Tibet Plateau area of China, which has a significant effect on relieving the course of rheumatoid arthritis (RA). However, the active compounds and underlying mechanisms of Ganlu Formula in RA treatment remain largely unexplored.

AIM OF THE STUDY

This study aimed to elucidate the active substances and potential mechanisms of the ethyl acetate extract of Ganlu Formula ethyl acetate extract (GLEE) in the treatment of RA.

MATERIALS AND METHODS

Ultra-performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry (UPLC-Q-TOF-MS) was utilized to analyze and identify the chemical constituents within GLEE. Discovery Studio molecular virtual docking technology was utilized to dock the interaction of GLEE with inflammation-related pathway proteins. The GLEE gene library was obtained by transcriptome sequencing. Collagen-induced arthritic（CIA) rats were utilized to assess the antiarthritic efficacy of GLEE. Micro-CT imaging was employed to visualize the rat paw, and ultrasound imaging revealed knee joint effusion. Evaluation of synovial tissue pathological changes was conducted through hematoxylin-eosin staining and saffranine solid green staining, while immunohistochemical staining was employed to assess NLRP3 expression along with inflammatory markers. Immunofluorescence staining was utilized to identify M1 macrophages.

RESULTS

Metabolomic analysis via UPLC-Q-TOF-MS identified 28 potentially bioactive compounds in GLEE, which interacted with the active sites of key proteins such as NLRP3, NF-κB, and STAT3 through hydrogen bonds, C-H bonds, and electrostatic attractions. In vitro analyses demonstrated that GLEE significantly attenuated NLRP3 inflammasome activation and inhibited the polarization of bone marrow-derived macrophages (BMDMs) towards the M1 phenotype. In vivo, GLEE not only prevented bone mineral density (BMD) loss but also reduced ankle swelling in CIA rats. Furthermore, it decreased the expression of the NLRP3 inflammasome and curtailed the release of inflammatory mediators within the knee joint.

CONCLUSION

GLEE effectively mitigated inflammatory responses in both blood and knee synovial membranes of CIA rats, potentially through the down-regulation of the NLRP3/Caspase-1/IL-1β signaling pathway and reduction in M1 macrophage polarization.

The impact of alternate-day fasting on the salivary gland stem cell compartments in non-obese diabetic mice with newly established Sjögren's syndrome

Intermittent fasting exerts a profound beneficial influence on a spectrum of diseases through various mechanisms including regulation of immune responses, elimination of senescent- and pathogenic cells and improvement of stem cell-based tissue regeneration in a disease- and tissue-dependent manner. Our previous study demonstrated that alternate-day fasting (ADF) led to alleviation of xerostomia and sialadenitis in non-obese diabetic (NOD) mice, a well-defined model of Sjögren's syndrome (SS). This present study delved into the previously unexplored impacts of ADF in this disease setting and revealed that ADF increases the proportion of salivary gland stem cells (SGSCs), defined as the EpCAMhi cell population among the lineage marker negative submandibular gland (SMG) cells. Furthermore, ADF downregulated the expression of p16INK4a, a cellular senescence marker, which was concomitant with increased apoptosis and decreased expression and activity of NLRP3 inflammasomes in the SMGs, particularly in the SGSC-residing ductal compartments. RNA-sequencing analysis of purified SGSCs from NOD mice revealed that the significantly downregulated genes by ADF were mainly associated with sugar metabolism, amino acid biosynthetic process and MAPK signaling pathway, whereas the significantly upregulated genes related to fatty acid metabolic processes, among others. Collectively, these findings indicate that ADF increases the SGSC proportion, accompanied by a modulation of the SGSC property and a switch from sugar- to fatty acid-based metabolism. These findings lay the foundation for further investigation into the functionality of SGSCs influenced by ADF and shed light on the cellular and molecular mechanisms by which ADF exerts beneficial actions on salivary gland restoration in SS.

Gelsolin alleviates rheumatoid arthritis by negatively regulating NLRP3 inflammasome activation

Despite numerous biomarkers being proposed for rheumatoid arthritis (RA), a gap remains in our understanding of their mechanisms of action. In this study, we discovered a novel role for gelsolin (GSN), an actin-binding protein whose levels are notably reduced in the plasma of RA patients. We elucidated that GSN is a key regulator of NLRP3 inflammasome activation in macrophages, providing a plausible explanation for the decreased secretion of GSN in RA patients. We found that GSN interacts with NLRP3 in LPS-primed macrophages, hence modulating the formation of the NLRP3 inflammasome complex. Reducing GSN expression significantly enhanced NLRP3 inflammasome activation. GSN impeded NLRP3 translocation to the mitochondria; it contributed to the maintenance of intracellular calcium equilibrium and mitochondrial stability. This maintenance is crucial for controlling the inflammatory response associated with RA. Furthermore, the exacerbation of arthritic symptoms in GSN-deficient mice indicates the potential of GSN as both a diagnostic biomarker and a therapeutic target. Moreover, not limited to RA models, GSN has demonstrated a protective function in diverse disease models associated with the NLRP3 inflammasome. Myeloid cell-specific GSN-knockout mice exhibited aggravated inflammatory responses in models of MSU-induced peritonitis, folic acid-induced acute tubular necrosis, and LPS-induced sepsis. These findings suggest novel therapeutic approaches that modulate GSN activity, offering promise for more effective management of RA and a broader spectrum of inflammatory conditions.

Nature of the Association between Rheumatoid Arthritis and Cervical Cancer and Its Potential Therapeutic Implications

It is now established that patients with rheumatoid arthritis (RA) have an increased risk of developing cervical cancer (CC) or its precursor, cervical intraepithelial neoplasia (CIN). However, the underlying mechanisms of this association have not been elucidated. RA is characterized by unresolved chronic inflammation. It is suggested that human papillomavirus (HPV) infection in RA patients exacerbates inflammation, increasing the risk of CC. The tumor microenvironment in RA patients with CC is also marked by chronic inflammation, which aggravates the manifestations of both conditions. Gut and vaginal dysbiosis are also considered potential mechanisms that contribute to the chronic inflammation and aggravation of RA and CC manifestations. Numerous clinical and pre-clinical studies have demonstrated the beneficial effects of various nutritional approaches to attenuate chronic inflammation, including polyunsaturated fatty acids and their derivatives, specialized pro-resolving mediators (SPMs), probiotics, prebiotics, and certain diets. We believe that successful resolution of chronic inflammation and correction of dysbiosis, in combination with current anti-RA and anti-CC therapies, is a promising therapeutic approach for RA and CC. This approach could also reduce the risk of CC development in HPV-infected RA patients.

The impacts of obesity in rheumatoid arthritis and insights into therapeutic purinergic modulation

Rheumatoid Arthritis (RA) is an autoimmune condition responsible for the impairment of synovia and joints, endangering the functionality of individuals and contributing to mortality. Currently, obesity is increasing worldwide, and recent studies have suggested an association between such condition and RA. In this sense, obese individuals present a lower capacity for achieving remission and present more intense symptoms of the disease, demonstrating a link between both disorders. Different studies aim to understand the possible connection between the conditions; however, few is known in this sense. Therefore, knowing that obesity can alter the activity of multiple body systems, this work's objective is to evaluate the main modifications caused by obesity, which can be linked to the pathophysiology of RA, highlighting as relevant topics obesity's negative impact triggering systemic inflammation, intestinal dysbiosis, endocrine disbalances. Furthermore, the relationship between oxidative stress and obesity also deserves to be highlighted, considering the influence of reactive oxygen species (ROS) accumulation in RA exacerbation. Additionally, many of those characteristics influenced by obesity, along with the classic peculiarities of RA pathophysiology, can also be associated with purinergic signaling. Hence, this work suggests possible connections between the purinergic system and RA, proposing potential therapeutic targets against RA to be studied.

Rheumatoid arthritis and diabetic retinopathy: A two-sample Mendelian randomization study

Diabetic retinopathy (DR) is a common and highly blinding disease. Many clinical studies have shown a causal relationship between Rheumatoid arthritis (RA) and DR, but the results are contradictory. In addition, some clinical results and pathological inferences have certain paradoxes, and the influence of RA on the pathogenesis and development of DR Is unclear. Our research assessed the causal association between RA and the development of DR using a 2-sample Mendelian randomization method. Single nucleotide polymorphisms (SNPs) relevant to the study were extracted and filtered from genome-wide association study (GWAS) data. A DR GWAS with a sample size of 190,594 and an RA GWAS with a sample size of 58,284 were obtained. Inverse variance weighted (IVW) method was used to analyze the results, and Mendelian randomization (MR)-Egger regression method and weighted median method were used to evaluate the robustness. Sensitivity analysis was performed using pleiotropy test, heterogeneity test, leave-one-out test to ensure that the results were unbiased. Confounding factors were eliminated to ensure robustness. A total of 83 related SNPs were screened. IVW method showed a positive correlation between RA and the increased relative risk of diabetic retinopathy (OR = 1.06, 95%CI: 1.04-1.23). The same trend was shown by MR-Egger regression method and weighted median method. Sensitivity analysis showed that there was no heterogeneity in SNPs, and the results were less likely to be affected by potential bias. After removing SNPs linked to confounders, the MR results remained significant and stable in direction. There is a positive causal association between rheumatoid arthritis and diabetic retinopathy. It is important to strengthen retina-related screening and prevention in diabetic patients with RA to reduce the risk of DR In RA patients.

Mechanistic insights into anti-inflammatory and immunosuppressive effects of plant secondary metabolites and their therapeutic potential for rheumatoid arthritis

The anti-inflammatory and immunosuppressive activities of plant secondary metabolites are due to their diverse mechanisms of action against multifarious molecular targets such as modulation of the complex immune system associated with rheumatoid arthritis (RA). This review discussed and critically analyzed the potent anti-inflammatory and immunosuppressive effects of several phytochemicals and their underlying mechanisms in association with RA in experimental studies, including preliminary clinical studies of some of them. A wide range of phytochemicals including phenols, flavonoids, chalcones, xanthones, terpenoids, alkaloids, and glycosides have shown significant immunosuppressive and anti-inflammatory activities in experimental RA models and a few have undergone clinical trials for their efficacy and safety in reducing RA symptoms and improve patient outcomes. These phytochemicals have potential as safer alternatives to the existing drugs in the management of RA, which possess a wide range of serious side effects. Sufficient preclinical studies on safety and efficacy of these phytochemicals must be performed prior to proper clinical studies. Further studies are needed to address the barriers that have so far limited their human use before the therapeutic potential of these plant-based chemicals as anti-arthritic agents in the treatment of RA is fully realized.

The Role of Inflammasome in Abdominal Aortic Aneurysm and Its Potential Drugs

Abdominal aortic aneurysm (AAA) has been recognized as a serious chronic inflammatory degenerative aortic disease in recent years. At present, there is no other effective intervention except surgical treatment for AAA. With the aging of the human population, its incidence is increasing year by year, posing a serious threat to human health. Modern studies suggest that vascular chronic inflammatory response is the core process in AAA occurrence and development. Inflammasome, a multiprotein complex located in the cytoplasm, mediates the expression of various inflammatory cytokines like interleukin (IL)-1β and IL-18, and thus plays a pivotal role in inflammation regulation. Therefore, inflammasome may exert a crucial influence on the progression of AAA. This article reviews some mechanism studies to investigate the role of inflammasome in AAA and then summarizes several potential drugs targeting inflammasome for the treatment of AAA, aiming to provide new ideas for the clinical prevention and treatment of AAA beyond surgical methods.

Guarea microcarpa C. DC. extract inhibits NLRP3 inflammasome by suppressing its ATPase activity

ETHNOPHARMACOLOGICAL RELEVANCE

Guarea genus comprises tropical and subtropical terrestrial herbs inhabiting Central and South America. These plants, including Guarea guidonia (L.) Sleumer, have anti-inflammatory, analgesic, antibacterial, antiviral, and immune-enhancing properties.

AIM OF THE STUDY

Although various species of the Guarea genus are known for their medicinal properties, comprehensive data on their anti-inflammatory effects remain limited. Therefore, we investigated the NLRP3 inflammasome-inhibiting effects of the Guarea genus in this study.

MATERIALS AND METHODS

To evaluate the anti-inflammatory activities of 18 members of the Guarea genus, we treated NLRP3 inflammasome activators with their extracts in LPS-primed J774A.1 and THP-1 cells. Cell viability was determined by water soluble tetrazolium salt (WST) and cytokine production, protein expression, and nuclear fractionation were determined by western blotting. Reactive oxygen species (ROS) production and apoptosis-associated speck-like protein containing a caspase recruitment domain (ASC) oligomerization were measured using confocal microscopic analysis. Inflammation-induced zebrafish was used in the in vivo experiments.

RESULTS

Among the 18 Guarea members tested, Guarea microcarpa C. DC. extract (GM) exhibited no cytotoxicity and specifically suppressed the activation of the NLRP3 inflammasome, but not of the AIM2 or NLRC4 inflammasomes, by inhibiting the ATPase activity of NLRP3. This was achieved without affecting NF-κB signaling, potassium efflux, or intracellular ROS production, all of which are involved in NLRP3 activation. The reduced ATPase activity of NLRP3 led to decreased ASC oligomerization. Furthermore, GM exhibited anti-inflammatory effects in vivo. Additionally, GM treatment alleviated inflammation at the organismal level in an LPS-induced inflammation model using zebrafish embryos.

CONCLUSION

Our results demonstrate the anti-inflammatory effects of GM via suppressing the NLRP3 inflammasome. Therefore, GM can be a potential therapeutic candidate for various inflammatory diseases caused by aberrant NLRP3 inflammasome activation.

The interaction of inflammasomes and gut microbiota: novel therapeutic insights

Inflammasomes are complex platforms for the cleavage and release of inactivated IL-1β and IL-18 cytokines that trigger inflammatory responses against damage-associated molecular patterns (DAMPs) or pathogen-associated molecular patterns (PAMPs). Gut microbiota plays a pivotal role in maintaining gut homeostasis. Inflammasome activation needs to be tightly regulated to limit aberrant activation and bystander damage to the host cells. Several types of inflammasomes, including Node-like receptor protein family (e.g., NLRP1, NLRP3, NLRP6, NLRP12, NLRC4), PYHIN family, and pyrin inflammasomes, interact with gut microbiota to maintain gut homeostasis. This review discusses the current understanding of how inflammasomes and microbiota interact, and how this interaction impacts human health. Additionally, we introduce novel biologics and antagonists, such as inhibitors of IL-1β and inflammasomes, as therapeutic strategies for treating gastrointestinal disorders when inflammasomes are dysregulated or the composition of gut microbiota changes.

Tolerogenic dendritic cells alleviate collagen-induced arthritis by regulating T-cell differentiation and inhibiting NLRP3-mediated apoptosis

OBJECTIVE

Tolerogenic dendritic cells (tolDCs) have emerged as a potential treatment for rheumatoid arthritis (RA). However, the detailed mechanism requires further investigation. In this study, we aimed to explore the effects of tolDCs on T-cell differentiation and NLRP3-mediated pyroptosis in a collagen-induced arthritis (CIA) rat model.

METHODS

TolDCs were induced using NF-κB ODN decoy. The efficacy of tolDCs intervention in alleviating arthritis symptoms was evaluated in CIA rats. Flow cytometry was employed to analyze CD4+ T-cell subpopulations, while scanning electron microscopy was utilized to observe pyroptosis morphology. Immunohistochemistry was used to assess the expression of pyroptosis-associated proteins.

RESULTS

TolDCs intervention significantly reduced joint inflammation and damage in CIA rats. Moreover, it successfully restored the balance of Th1/Th2 cells as well as the balance of Treg/Th17 cells. Furthermore, tolDCs intervention effectively suppressed NLRP3-mediated pyroptosis in the synovium, decreasing the release of IL-1β and IL-18.

CONCLUSION

Our findings underscore the efficacy of tolDCs in attenuating CIA progression through modulation of CD4+ T-cell subpopulations and inhibition of NLRP3-mediated pyroptosis.

The Genetic Landscape of Systemic Rheumatic Diseases: A Comprehensive Multigene-Panel Study Identifying Key Gene Polymorphisms

Systemic rheumatic diseases, including conditions such as rheumatoid arthritis, Sjögren's syndrome, systemic sclerosis, and systemic lupus erythematosus, represent a complex array of autoimmune disorders characterized by chronic inflammation and diverse clinical manifestations. This study focuses on unraveling the genetic underpinnings of these diseases by examining polymorphisms in key genes related to their pathology. Utilizing a comprehensive genetic analysis, we have documented the involvement of these genetic variations in the pathogenesis of rheumatic diseases. Our study has identified several key polymorphisms with notable implications in rheumatic diseases. Polymorphism at chr11_112020916 within the IL-18 gene was prevalent across various conditions with a potential protective effect. Concurrently, the same IL18R1 gene polymorphism located at chr2_103010912, coding for the IL-18 receptor, was observed in most rheumatic conditions, reinforcing its potential protective role. Additionally, a further polymorphism in IL18R1 at chr2_103013408 seems to have a protective influence against the rheumatic diseases under investigation. In the context of emerging genes involved in rheumatic diseases, like PARK2, a significant polymorphism at chr6_161990516 was consistently identified across different conditions, exhibiting protective characteristics in these pathological contexts. The findings underscore the complexity of the genetic landscape in rheumatic autoimmune disorders and pave the way for a deeper understanding of their etiology and the possible development of more targeted and effective therapeutic strategies.

Macrophage extracellular traps require peptidylarginine deiminase 2 and 4 and are a source of citrullinated antigens bound by rheumatoid arthritis autoantibodies

Introduction

Anti-citrullinated protein antibodies (ACPAs) are a hallmark of rheumatoid arthritis, but the sources of citrullinated antigens as well as which peptidylarginine deiminases (PADs) are required for their production remain incompletely defined. Here, we investigated if macrophage extracellular traps (METs) could be a source of citrullinated proteins bound by APCAs, and if their formation requires PAD2 or PAD4.

Methods

Thioglycolate-induced peritoneal macrophages from wild-type, PAD2-/-, and PAD4-/- mice or human peripheral blood-derived M1 macrophages were activated with a variety of stimulants, then fixed and stained with DAPI and either anti-citrullinated histone H4 (citH4) antibody or sera from ACPA+ or ACPA- rheumatoid arthritis subjects. METs were visualized by immunofluorescence, confirmed to be extracellular using DNase, and quantified.

Results

We found that ionomycin and monosodium urate crystals reliably induced murine citH4+ METs, which were reduced in the absence of PAD2 and lost in the absence of PAD4. Also, IgG from ACPA+, but not ACPA-, rheumatoid arthritis sera bound to murine METs, and in the absence of PAD2 or PAD4, ACPA-bound METs were lost. Finally, ionomycin induced human METs that are citH4+ and ACPA-bound.

Discussion

Thus, METs may contribute to the pool of citrullinated antigens bound by ACPAs in a PAD2- and PAD4-dependent manner, providing new insights into the targets of immune tolerance loss in rheumatoid arthritis.

Roles of the Caspase-11 Non-Canonical Inflammasome in Rheumatic Diseases

Inflammasomes are intracellular multiprotein complexes that activate inflammatory signaling pathways. Inflammasomes comprise two major classes: canonical inflammasomes, which were discovered first and are activated in response to a variety of pathogen-associated molecular patterns (PAMPs) and danger-associated molecular patterns (DAMPs), and non-canonical inflammasomes, which were discovered recently and are only activated in response to intracellular lipopolysaccharide (LPS). Although a larger number of studies have successfully demonstrated that canonical inflammasomes, particularly the NLRP3 inflammasome, play roles in various rheumatic diseases, including rheumatoid arthritis (RA), infectious arthritis (IR), gouty arthritis (GA), osteoarthritis (OA), systemic lupus erythematosus (SLE), psoriatic arthritis (PA), ankylosing spondylitis (AS), and Sjögren's syndrome (SjS), the regulatory roles of non-canonical inflammasomes, such as mouse caspase-11 and human caspase-4 non-canonical inflammasomes, in these diseases are still largely unknown. Interestingly, an increasing number of studies have reported possible roles for non-canonical inflammasomes in the pathogenesis of various mouse models of rheumatic disease. This review comprehensively summarizes and discusses recent emerging studies demonstrating the regulatory roles of non-canonical inflammasomes, particularly focusing on the caspase-11 non-canonical inflammasome, in the pathogenesis and progression of various types of rheumatic diseases and provides new insights into strategies for developing potential therapeutics to prevent and treat rheumatic diseases as well as associated diseases by targeting non-canonical inflammasomes.

Anethole mitigates H2 O2 -induced inflammation in HIG-82 synoviocytes by suppressing the aquaporin 1 expression and activating the protein kinase A pathway

Rheumatoid arthritis (RA) is an autoimmune inflammatory disease affecting approximately 1% of the global population, with a higher prevalence in women than in men. Chronic inflammation and oxidative stress play pivotal roles in the pathogenesis of RA. Anethole, a prominent compound derived from fennel (Foeniculum vulgare), possesses a spectrum of therapeutic properties, including anti-arthritic, anti-inflammatory, antioxidant, and tumor-suppressive effects. However, its specific impact on RA remains underexplored. This study sought to uncover the potential therapeutic value of anethole in treating RA by employing an H2 O2 -induced inflammation model with HIG-82 synovial cells. Our results demonstrated that exposure to H2 O2 induced the inflammation and apoptosis in these cells. Remarkably, anethole treatment effectively countered these inflammatory and apoptotic processes triggered by H2 O2 . Moreover, we identified the aquaporin 1 (AQP1) and protein kinase A (PKA) pathway as critical regulators of inflammation and apoptosis. H2 O2 stimulation led to an increase in the AQP1 expression and a decrease in p-PKA-C, contributing to cartilage degradation. Conversely, anethole not only downregulated the AQP1 expression but also activated the PKA pathway, effectively suppressing cell inflammation and apoptosis. Furthermore, anethole also inhibited the enzymes responsible for cartilage degradation. In summary, our findings highlight the potential of anethole as a therapeutic agent for mitigating H2 O2 -induced inflammation and apoptosis in synovial cells, offering promising prospects for future RA treatments.

Nod-like receptors in inflammatory arthritis

Nod-like receptors (NLRs) are innate immune receptors that play a key role in sensing components from pathogens and from damaged cells or organelles. NLRs form signaling complexes that can lead to activation of transcription factors or effector caspases - by means of inflammasome activation -Inflammatory arthritis (IA) culminating in promoting inflammation. An increasing body of research supports the role of NLRs in driving pathogenesis of IA, a collection of diseases that include rheumatoid arthritis (RA), psoriatic arthritis (PsA), ankylosing spondylitis, and pediatric arthritis. In this review, we briefly discuss the main drivers of IA diseases and dive into the evidence for - and against - various NLRs in driving these diseases. We also review the studies examining the use of NLR and inflammasome inhibitors as potential therapies for IA.

The NLRP3 inflammasome: a vital player in inflammation and mediating the anti-inflammatory effect of CBD

BACKGROUND

The NLRP3 inflammasome is a vital player in the emergence of inflammation. The priming and activation of the NLRP3 inflammasome is a major trigger for inflammation which is a defense response against adverse stimuli. However, the excessive activation of the NLRP3 inflammasome can lead to the development of various inflammatory diseases. Cannabidiol, as the second-most abundant component in cannabis, has a variety of pharmacological properties, particularly anti-inflammation. Unlike tetrahydrocannabinol, cannabidiol has a lower affinity for cannabinoid receptors, which may be the reason why it is not psychoactive. Notably, the mechanism by which cannabidiol exerts its anti-inflammatory effect is still unclear.

METHODS

We have performed a literature review based on published original and review articles encompassing the NLRP3 inflammasome and cannabidiol in inflammation from central databases, including PubMed and Web of Science.

RESULTS AND CONCLUSIONS

In this review, we first summarize the composition and activation process of the NLRP3 inflammasome. Then, we list possible molecular mechanisms of action of cannabidiol. Next, we explain the role of the NLRP3 inflammasome and the anti-inflammatory effect of cannabidiol in inflammatory disorders. Finally, we emphasize the capacity of cannabidiol to suppress inflammation by blocking the NLRP3 signaling pathway, which indicates that cannabidiol is a quite promising anti-inflammatory compound.

The NLRP3 Inflammasome as a Pathogenic Player Showing Therapeutic Potential in Rheumatoid Arthritis and Its Comorbidities: A Narrative Review

Rheumatoid arthritis (RA) is an autoimmune inflammatory disease characterized by chronic synovitis and the progressive destruction of cartilage and bone. RA is commonly accompanied by extra-articular comorbidities. The pathogenesis of RA and its comorbidities is complex and not completely elucidated. The assembly of the NOD-, LRR- and pyrin domain-containing protein 3 (NLRP3) inflammasome activates caspase-1, which induces the maturation of interleukin (IL)-1β and IL-18 and leads to the cleavage of gasdermin D with promoting pyroptosis. Accumulative evidence indicates the pathogenic role of NLRP3 inflammasome signaling in RA and its comorbidities, including atherosclerotic cardiovascular disease, osteoporosis, and interstitial lung diseases. Although the available therapeutic agents are effective for RA treatment, their high cost and increased infection rate are causes for concern. Recent evidence revealed the components of the NLRP3 inflammasome as potential therapeutic targets in RA and its comorbidities. In this review, we searched the MEDLINE database using the PubMed interface and reviewed English-language literature on the NLRP3 inflammasome in RA and its comorbidities from 2000 to 2023. The current evidence reveals that the NLRP3 inflammasome contributes to the pathogenesis of RA and its comorbidities. Consequently, the components of the NLRP3 inflammasome signaling pathway represent promising therapeutic targets, and ongoing research might lead to the development of new, effective treatments for RA and its comorbidities.

Mechanisms of NLRP3 inflammasome activation and the development of peptide inhibitors

The Nucleotide-binding domain leucine-rich repeat and pyrin domain containing receptor 3 (NLRP3), a member of the nucleotide-binding oligomerization domain (NOD) like receptors (NLRs) family, plays an important role in the innate immune response against pathogen invasions. NLRP3 inflammasome consisting of NLRP3 protein, the adapter protein apoptosis-associated speck-like protein containing a caspase recruitment domain (CARD) (ASC), and the effector protein pro-caspase-1, is central to this process. Upon activation, NLRP3 inflammasome initiates the release of inflammatory cytokines and triggers a form of cell death known as pyroptosis. Dysregulation or inappropriate activation of NLRP3 has been implicated in various human diseases, including type 2 diabetes, colitis, depression, and gout. Consequently, understanding the mechanism underlying NLRP3 inflammasome activation is critical for the development of therapeutic drugs. In the pursuit of potential therapeutic agents, peptides present several advantages over small molecules. They offer higher selectivity, increased potency, reduced toxicity, and fewer off-target effects. The advancements in molecular biology have expanded the opportunities for applying peptides in medicine, unlocking their vast medical potential. This review begins by providing a comprehensive summary of recent research progress regarding the mechanisms governing NLRP3 inflammasome activation. Subsequently, we offer an overview of current peptide inhibitors capable of modulating the NLRP3 inflammasome activation pathway.

Immune mechanisms of depression in rheumatoid arthritis

Depression is a common and disabling comorbidity in rheumatoid arthritis that not only decreases the likelihood of remission and treatment adherence but also increases the risk of disability and mortality in patients with rheumatoid arthritis. Compelling data that link immune mechanisms to major depressive disorder indicate possible common mechanisms that drive the pathology of the two conditions. Preclinical evidence suggests that pro-inflammatory cytokines, which are prevalent in rheumatoid arthritis, have various effects on monoaminergic neurotransmission, neurotrophic factors and measures of synaptic plasticity. Neuroimaging studies provide insight into the consequences of inflammation on the brain (for example, on neural connectivity), and clinical trial data highlight the beneficial effects of immune modulation on comorbid depression. Major depressive disorder occurs more frequently in patients with rheumatoid arthritis than in the general population, and major depressive disorder also increases the risk of a future diagnosis of rheumatoid arthritis, further highlighting the link between rheumatoid arthritis and major depressive disorder. This Review focuses on interactions between peripheral and central immunobiological mechanisms in the context of both rheumatoid arthritis and major depressive disorder. Understanding these mechanisms will provide a basis for future therapeutic development, not least in depression.

Role of some inflammasomes in rheumatoid arthritis patients in Egypt

AIM

This study aims to demonstrate the role of some inflammasomes genes: NLRC4 (the NLR family, CARD domain-containing protein 4), NLRP1 (NLR family, pyrin domain-containing 1), ASC (Apoptosis-associated speck-like protein containing a CARD), and CASPASE-1 in the pathogenesis of Rheumatoid arthritis (RA) in Egyptian population.

MAIN METHODS

The expression level of NLRC4, NLRP1, ASC, and CASPASE-1 within PBMCs isolated from all RA subjects by quantitative real-time PCR. GAPDH gene was used as a reference gene. Measurement of serum level of IL-1β and IL-18 was performed using ELISA.

KEY FINDINGS

Results showed dysregulated inflammasomes expression that may participate in the pathogenesis of the inflammatory process of the disease.

SIGNIFICANCE

Understanding the role of inflammasomes in RA pathogenesis helps in finding promising therapy for the treatment and management of this disease.

Identification of potential ferroptosis key genes and immune infiltration in rheumatoid arthritis by integrated bioinformatics analysis

Objective

Ferroptosis is of vital importance in the development of Rheumatoid arthritis (RA). The purpose of this project is to clarify the potential ferroptosis-related genes, pathways, and immune infiltration in RA by bioinformatics analysis.

Methods

We acquired ferroptosis-related genes (FRGs) from Ferroptosis database (FerrDb). We obtained the Gene dataset of RA (GSE55235) from the Gene Expression Omnibus (GEO) Database, screened the differentially expressed genes (DEGs) in RA and control samples, and then took the intersection of it and FRGs. Aiming to construct the protein-protein interaction (PPI) networks of the FRGs-DEGs, STRING database and Cytoscape software 3.7.0 would be used. Furthermore, hub genes were identified by CytoNCA, a Cytoscape plug-in. The gene ontology (GO) and the Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment of FRGs-DEGs were performed.

Results

We identified 34 FRGs-DEGs, including 7 upregulated and 27 downregulated genes by taking the intersection of the FRGs and DEGs. PPI analysis identified a total of 3 hub genes(VEGFA, PTGS2, and JUN). GO enrichment analyses and KEGG Pathway enrichment displayed that the FRGs-DEGs are involved in the response to oxidative stress and corticosteroid, heme binding, FoxO-signal pathway. Results of immune infiltration displayed that increased infiltration of T cells, while Macrophages M2 less may be related to the occurrence of RA.

Conclusion

The hub genes involved in ferroptosis in RA may be VEGFA, PTGS2, and JUN, which are mainly involved in FoxO-signal pathway. T cell, Mac, and plasma cells may be involved in the regulation of RA-joints-synovial-inflammation.

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.

The genesis of cardiovascular risk in inflammatory arthritis: insights into glycocalyx shedding, endothelial dysfunction, and atherosclerosis initiation

This narrative review provides a comprehensive examination of the complex interplay between inflammatory arthritis (IA) and cardiovascular pathology. It particularly illuminates the roles of atherosclerosis initiation, endothelial dysfunction, and glycocalyx shedding. IA not only provokes tissue-specific inflammatory responses, but also engenders a considerable degree of non-specific systemic inflammation. This review underscores the accelerating influence of the chronic inflammatory milieu of IA on cardiovascular disease (CVD) progression. A focal point of our exploration is the critical function of the endothelial glycocalyx (EG) in this acceleration process, which possibly characterizes the earliest phases of atherosclerosis. We delve into the influence of inflammatory mediators on microtubule dynamics, EG modulation, immune cell migration and activation, and lipid dysregulation. We also illuminate the impact of microparticles and microRNA on endothelial function. Further, we elucidate the role of systemic inflammation and sheddases in EG degradation, the repercussions of complement activation, and the essential role of syndecans in preserving EG integrity. Our review provides insight into the complex and dynamic interface between systemic circulation and the endothelium.