Syndecan-4 involves in the pathogenesis of rheumatoid arthritis by regulating the inflammatory response and apoptosis of fibroblast-like synoviocytes

Serum levels of free light chains and syndecan-1 in patients with rheumatoid arthritis and systemic lupus erythematosus

OBJECTIVES

Systemic autoimmune rheumatic diseases (SARDs) are characterized by chronic inflammation. Reliable biomarkers are crucial for diagnosis, monitoring disease progression and therapeutic responses. This study explores serum syndecan-1 (SDC-1) as a biomarker for these conditions and its relationship with free light chain (FLC) levels.

METHODS

A retrospective analysis was performed on sera from 60 patients with rheumatoid arthritis (RA) and from 60 with systemic lupus erythematosus (SLE), alongside 50 healthy donors (HD). Κ- and λ- FLCs were determined by turbidimetric assay, while SDC-1 levels were determined by ELISA. Kruskal-Wallis test, Wilcoxon Mann-Whitney U test, multivariable linear regression and Spearman's correlation were employed to compare biomarker levels across groups and to explore correlations.

RESULTS

SDC-1, κ-FLC and λ-FLC were significantly increased in RA and SLE patients compared with HD (P < 0.001), while no significant differences in the κ/λ ratio were observed among the groups (P = 0.4). A significant difference in subject age was also identified. However, multivariate regression analysis indicated that RA and SLE are significantly associated with the levels of these markers, with minimal confounding by age. A significant correlation was observed separately in all groups between the FLC markers. Conversely, no correlation was detected between SDC-1 and FLCs, nor between these markers and age or disease activity indices.

CONCLUSION

Elevated serum levels of FLCs and SDC-1 in RA and SLE patients compared with HD underscore their potential as biomarkers for SARDs. The findings also suggest sustained plasma cell activation, supporting the multifaceted role of SDC-1 in the pathogenesis of SARDs.

Identification the role of necroptosis in rheumatoid arthritis by WGCNA network

Rheumatoid arthritis (RA) is the predominant manifestation of inflammatory arthritis, distinguished by an increasing burden of morbidity and mortality. The intricate interplay of genes and signalling pathways involved in synovial inflammation in patients with RA remains inadequately comprehended. This study aimed to ascertain the role of necroptosis in RA, as along with their associations with immune cell infiltration. Differential expression analysis and weighted gene co-expression network analysis (WGCNA) were employed to identify central genes for RA. In this study, identified total of 28 differentially expressed genes (DEGs) were identified in RA. Utilising WGCNA, two co-expression modules were generated, with one module demonstrating the strongest correlation with RA. Through the integration of differential gene expression analysis, a total of 5 intersecting genes were discovered. These 5 hub genes, namely fused in sarcoma (FUS), transformer 2 beta homolog (TRA2B), eukaryotic translation elongation factor 2 (EEF2), cleavage and polyadenylation specific factor 6 (CPSF6) and signal transducer and activator of transcription 3 (STAT3) were found to possess significant diagnostic value as determined by receiver operating characteristic (ROC) curve analysis. The close association between the concentrations of various immune cells is anticipated to contribute to the diagnosis and treatment of RA. Furthermore, the infiltration of immune cells mentioned earlier is likely to exert a substantial influence on the initiation of this disease.

Intermittent fasting reduces inflammation and joint damage in a murine model of rheumatoid arthritis: insights from transcriptomic and metagenomic analyses

BACKGROUND

Intermittent fasting (IF) has shown benefits in various pathological conditions. Although its anti-inflammatory potential has been recognized, its effects on the mechanism underlying rheumatoid arthritis (RA) remain insufficiently characterized. This study aimed to investigate the effects of IF in a murine model of RA.

METHODS

Collagen-induced arthritis (CIA) was developed in sixteen male DBA/1 mice, randomly assigned to two groups, with one undergoing IF every other day for four weeks. The effects of IF on joint inflammation and remodeling were evaluated clinically, histologically, and through tomography. Transcriptomic changes were characterized using expression microarrays, validated by RT-qPCR, and confirmed by immunohistochemistry. Additionally, modifications in gut microbiota were assessed through 16 S sequencing.

RESULTS

Mice subjected to IF significantly reduced the incidence and severity of clinical arthritis. Histological and radiographic assessments confirmed a decrease in inflammation and joint damage. Transcriptomic analysis revealed that IF led to the upregulation of 364 genes and the downregulation of 543 genes, with notable reductions in inflammatory signaling pathways associated with RA-related genes, including Cd72, Cd79a, Ifna, Il33, and Bglap 2. Notably, IL33 emerged as a pivotal mediator in the inflammatory processes mitigated by fasting. Key regulators associated with IF effects, such as CEBPA, FOXO1, HIF1A, PPARG, and PPARA, were identified, indicating a complex interplay between metabolic and inflammatory pathways. Furthermore, differential expression of microRNAs and lncRNAs, including miR-15b, miR-103-2, miR-302a, miR-6985, and miR- 5624, was observed. Metagenomic analysis indicated that IF enhanced the abundance and diversity of the gut microbiome, explicitly promoting anti-inflammatory bacterial populations, notably within the genus Ruminococcaceae.

CONCLUSION

Our findings suggest that IF exerts significant anti-inflammatory and immunoregulatory effects in the context of CIA. Given its non-risky nature, further investigation into the potential benefits of IF in patients with RA is warranted.

CLINICAL TRIAL NUMBER

Not applicable.

Super-Enhancer-Driven Syndecan-4 Regulates Intercellular Communication in Hypoxic Pulmonary Hypertension

BACKGROUND

Unveiling pro-proliferation genes involved in crosstalk between pulmonary artery endothelial cells and pulmonary artery smooth muscle cells (PASMCs) are important to improving the therapeutic outcome of pulmonary hypertension (PH). Although growing studies have shown that super-enhancers (SEs) play a pivotal role in pathological and physiological processes, the SE-associated genes in PH and their impact on PASMC proliferation remain largely unexplored.

METHODS AND RESULTS

We used serotype 5 adenovirus-associated virus to interfere with syndecan-4 and constructed an SU5416 combined with hypoxia-PH model. Chromatin immunoprecipitation sequencing analysis, chromatin immunoprecipitation quantitative polymerase chain reaction, and bioinformatics were used to confirm early growth response 1 was involved in regulating syndecan-4-associated SE in PASMCs. The effects of syndecan-4 and its underlying mechanisms were subsequently elucidated using Western blot, coimmunoprecipitation, and cell coculture assays. Herein, we identified a novel SE-associated gene, syndecan-4, in hypoxia-exposed PASMCs. Syndecan-4 was transcriptionally driven by early growth response 1 via an SE and was significantly overexpressed in hypoxic PASMCs and plasma from patients with PH. Mechanism studies revealed that syndecan-4 induces PASMC proliferation by interacting and regulating protein kinase C α ubiquitination. In addition, syndecan-4 was enriched in exosomes secreted from hypoxic PASMCs, which subsequently transported and led to pulmonary artery endothelial cell dysfunction. Syndecan-4 inhibition in hypoxia by serotype 5 adenovirus-associated virus treatment attenuated the pulmonary artery remodeling and development of PH in vivo.

CONCLUSIONS

Taken together, our results demonstrate that an SE-driven syndecan-4 modulates crosstalk of PASMCs and pulmonary artery endothelial cells and promotes vascular remodeling via the protein kinase C α and exosome pathway, thus providing potential targets for the early diagnosis and treatment of hypoxic PH.

Exploring the Mechanism of Acupuncture's Influence on the Protease Activity and Free Radical Damage in Synovial Fluid of Rheumatoid Arthritis Rats Induced by Type II Collagen from the Release of Active Oxygen

Acupuncture was studied to investigate the mechanism of its effect on protease vitality and free radical damage in Type I CIA rats induced by type II collagen. The study divided rats into a control group (injected with physiological saline, n = 10), a model group (injected with type II collagen, n = 10), and an intervention group (injected with type II collagen + acupuncture ST36 and GB39, 3 times a week, for a total of 4 weeks, n = 10) based on the different injected drugs. Then, various indicators of the mice were experimentally tested using joint index scoring, H&E histological staining, protein blotting, and immunohistochemistry staining methods. Acupuncture ST36 and GB39 can reduce arthritis scores, histological staining scores, and increase MVD in CIA rats. And reduce protease levels, alleviate inflammation, synovial hyperplasia, and angiogenesis. In addition, the intervention group TNF-α, IL-1β and IL-6 mRNA were reduced, and the clearance rates of hydrogen peroxide free radicals and nitric oxide free radicals were increased. The expression levels of ROS and MDA decrease, while the expression levels of SOD increase It has been proved that acupuncture at ST36 and GB39 can inhibit the release of ROS, reduce protease activity, inflammation, synovial hyperplasia, angiogenesis and free radical damage, thus reducing the severity of CIA (Collagen-Induced Arthritis) in rats.

Inflammatory tissue priming: novel insights and therapeutic opportunities for inflammatory rheumatic diseases

Due to optimised treatment strategies and the availability of new therapies during the last decades, formerly devastating chronic inflammatory diseases such as rheumatoid arthritis or systemic sclerosis (SSc) have become less menacing. However, in many patients, even state-of-the-art treatment cannot induce remission. Moreover, the risk for flares strongly increases once anti-inflammatory therapy is tapered or withdrawn, suggesting that underlying pathological processes remain active even in the absence of overt inflammation. It has become evident that tissues have the ability to remember past encounters with pathogens, wounds and other irritants, and to react more strongly and/or persistently to the next occurrence. This priming of the tissue bears a paramount role in defence from microbes, but on the other hand drives inflammatory pathologies (the Dr Jekyll and Mr Hyde aspect of tissue adaptation). Emerging evidence suggests that long-lived tissue-resident cells, such as fibroblasts, macrophages, long-lived plasma cells and tissue-resident memory T cells, determine inflammatory tissue priming in an interplay with infiltrating immune cells of lymphoid and myeloid origin, and with systemically acting factors such as cytokines, extracellular vesicles and antibodies. Here, we review the current state of science on inflammatory tissue priming, focusing on tissue-resident and tissue-occupying cells in arthritis and SSc, and reflect on the most promising treatment options targeting the maladapted tissue response during these diseases.

Syndecan-4 is the key proteoglycan involved in mediating sepsis-associated lung injury

Vascular endothelial cell dysfunction involving syndecan (SDC) proteoglycans contributes to acute sepsis-associated lung injury (ALI), but the exact SDC isoform involved is unclear. We aimed to clarify which SDCs are involved in ALI. A relevant gene expression dataset (GSE5883) was analysed for differentially expressed genes (DEGs) between lipopolysaccharide (LPS)-treated and control lung endothelial cells and for SDC isoform expression. Bioinformatic analyses to predict DEG function were conducted using R language, Gene Ontology, and the Kyoto Encyclopedia of Genes and Genomes. SDC2 and SDC4 expression profiles were examined under inflammatory conditions in human lung vascular endothelial cell and mouse sepsis-associated ALI models. Transcription factors regulating SDC2/4 were predicted to indirectly assess SDC involvement in septic inflammation. Of the DEGs, 224 and 102 genes were up- and downregulated, respectively. Functional analysis indicated that DEGs were involved in modulating receptor ligand and signalling receptor activator activities, cytokine receptor binding, responses to LPS and molecules of bacterial origin, regulation of cell adhesion, tumour necrosis factor signalling, and other functions. DEGs were also enriched for cytoplasmic ribonucleoprotein granules, transcription regulator complexes, and membrane raft cellular components. SDC4 gene expression was 4.5-fold higher in the LPS group than in the control group, while SDC2 levels were similar in both groups. SDC4 mRNA and protein expression was markedly upregulated in response to inflammatory injury, and SDC4 downregulation severely exacerbated inflammatory responses in both in vivo and in vitro models. Overall, our data demonstrate that SDC4, rather than SDC2, is involved in LPS-induced sepsis-associated ALI.

Bioinformatics analysis of rheumatoid arthritis tissues identifies genes and potential drugs that are expressed specifically

Studies have implicated necroptosis mechanisms in orthopaedic-related diseases, since necroptosis is a unique regulatory cell death pattern. However, the role of Necroptosis-related genes in rheumatoid arthritis (RA) has not been well described. We downloaded RA-related data information and Necroptosis-related genes from the Gene Expression Omnibus (GEO), Kyoto Gene and Genome Encyclopedia (KEGG) database, and Genome Enrichment Analysis (GSEA), respectively. We identified 113 genes associated with RA-related necroptosis, which was closely associated with the cytokine-mediated signaling pathway, necroptosis and programmed necrosis. Subsequently, FAS, MAPK8 and TNFSF10 were identified as key genes among 48 Necroptosis-associated differential genes by three machine learning algorithms (LASSO, RF and SVM-RFE), and the key genes had good diagnostic power in distinguishing RA patients from healthy controls. According to functional enrichment analysis, these genes may regulate multiple pathways, such as B-cell receptor signaling, T-cell receptor signaling pathways, chemokine signaling pathways and cytokine-cytokine receptor interactions, and play corresponding roles in RA. Furthermore, we predicted 48 targeted drugs against key genes and 31 chemical structural formulae based on targeted drug prediction. Moreover, key genes were associated with complex regulatory relationships in the ceRNA network. According to CIBERSORT analysis, FAS, MAPK8 and TNFSF10 may be associated with changes in the immune microenvironment of RA patients. Our study developed a diagnostic validity and provided insight to the mechanisms of RA. Further studies will be required to test its diagnostic value for RA before it can be implemented in clinical practice.

Syndecan-4 is correlated with disease activity and serological characteristic of rheumatoid arthritis

Objectives

To describe the feature of expression of syndecan-4 in serum, synovial fluid (SF) and synovium in rheumatoid arthritis (RA) patients, and to analyze the correlation of syndecan-4 with disease activity and serological characteristic of RA.

Methods

Syndecan-4 in sera of 60 RA patients, 20 osteoarthritis (OA) patients, 20 healthy controls, and in SF of 25 RA patients and 25 OA patients were tested by enzyme linked immunosorbant assay. The expressions of syndecan-4 in synovium of RA and OA patients were detected by immunohistochemistry. The expression of syndecan-4 on synovial fibroblasts from RA and OA patients were detected by immunofluorescence. The correlation between serum syndecan-4 concentration and disease activity were analyzed in RA patients.

Results

The serum syndedcan-4 concentration was significantly higher in RA patients than in OA patients and healthy controls, and was higher in rheumatoid factor (RF)-positive RA patients than in RF-negative ones. Syndecan-4 concentration in SF of RA patients was comparable with OA patients. Syndecan-4 expression in synovial tissue was similar between RA and OA patients. The syndecan-4 concentration was significantly lower in SF than in serum of RA and OA patients. Syndecan-4 concentration in both serum and SF was positively correlated with disease activity of RA patients.

Conclusion

The serum syndecan-4 concentration was higher in RA patients than in OA patients, and significantly higher in RF-positive RA patients than in RF-negative ones. Syndecan-4 concentration in both serum and SF was positively correlated with disease activity of RA patients.

Comprehensive analysis of the expression of N6-methyladenosine RNA methylation regulators in pulmonary artery hypertension

Background: Pulmonary arterial hypertension (PAH) is a progressive disease characterized by pulmonary vascular remodeling. The development of PAH involves N6-methyladenosine (m6A) modification. However, the functional role of m6A regulators in PAH and the underlying regulatory mechanisms remain unknown so far.

Methods: Microarray data (GSE149713) for monocrotaline induced PAH (MCT-PAH) rat models were downloaded and screened for differentially expressed genes (DEGs) and m6A regulators. Next, we screened for differentially expressed m6A regulators in endothelial cells (ECs), smooth muscle cells (SMCs), fibroblasts, interstitial macrophages, NK cells, B cells, T cells, regulatory T cells (Tregs) using scRNA sequencing data. The target DEGs of m6A regulators in ECs, SMCs, fibroblasts, and Tregs were functionally annotated using the Gene Ontology (GO) functional analysis and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis. In addition, the cellular interaction analysis was performed to reveal the receptor—ligand pairs regulated by m6A regulators. Pseudo-time trajectory analyses were performed and a ceRNA network of lncRNAs-miRNAs-mRNAs was constructed in SMCs. Furthermore, the RNA transcriptome sequencing data for the SMCs isolated from idiopathic PAH (IPAH) patients (GSE144274) were validated for differentially expressed m6A regulators. Moreover, the HNRNPA2B1 levels in the lung samples from PAH patients and MCT-PAH were determined using immunohistochemistry.

Results: The m6A regulators were observed to be dysregulated in PAH. HNRNPA2B1expression level was increased in the PASMCs of scRNAs and IPAH patients. The target DEGs of HNRNPA2B1 were enriched in the regulation of muscle cell differentiation and vasculature development in PASMCs. The HNRNPA2B1 expression levels determined were consistent with the proliferation-related and collagen synthesis-related gene COL4A1. Moreover, the predicted transcription factors (TFs) foxd2/3 and NFκB could be involved in the regulation of HNRNPA2B1. HNRNPA2B1 might be regulating SMCs proliferation and phenotypic transition via rno-miR-330–3p/TGFβR3 and rno-miR-125a-3p/slc39a1. In addition, HNRNPA2B1 was observed to be highly expressed in the lung samples from MCT-PAH rat models and patients with PAH.

Conclusion: In summary, the present study identified certain key functional m6A regulators that are involved in pulmonary vascular remodeling. The investigation of m6A patterns might be promising and provide biomarkers for diagnosis and treatment of PAH in the future.

A reduction of Syndecan-4 in macrophages promotes atherosclerosis by aggravating the proinflammatory capacity of macrophages

BACKGROUND

Cardiovascular diseases (CVDs) are a significant cause of mortality worldwide and are characterized by severe atherosclerosis (AS) in patients. However, the molecular mechanism of AS formation remains elusive. In the present study, we investigated the role of syndecan-4 (SDC4), a member of the syndecan family, in atherogenesis.

METHODS AND RESULTS

The expression of SDC4 decreased in mouse severe AS models. Moreover, knockout of SDC4 accelerated high-cholesterol diets (HCD)-induced AS in ApoE^-/- mice. Mechanistically, the decrease of SDC4 increased macrophage proinflammatory capacity may be through the PKCα-ABCA1/ABCG1 signaling pathway.

CONCLUSION

These findings provide evidence that SDC4 reduction links macrophages and inflammation to AS and that SDC4 in macrophages provides a therapeutic target for preventing AS formation.

Synovial fibroblasts as potential drug targets in rheumatoid arthritis, where do we stand and where shall we go?

Fibroblast-like synoviocytes or synovial fibroblasts (FLS) are important cellular components of the inner layer of the joint capsule, referred to as the synovial membrane. They can be found in both layers of this synovial membrane and contribute to normal joint function by producing extracellular matrix components and lubricants. However, under inflammatory conditions like in rheumatoid arthritis (RA), they may start to proliferate, undergo phenotypical changes and become central elements in the perpetuation of inflammation through their direct and indirect destructive functions. Their importance in autoimmune joint disorders makes them attractive cellular targets, and as mesenchymal-derived cells, their inhibition may be carried out without immunosuppressive consequences. Here, we aim to give an overview of our current understanding of the target potential of these cells in RA.

Emerging proteoglycans and proteoglycan-targeted therapies in rheumatoid arthritis

Rheumatoid arthritis (RA) is a common auto-immune disease-causing inflammation of the joints and damage of the cartilage and bone. The pathogenesis of RA is characterized in many patients by the presence of antibodies against citrullinated proteins. In the joints, proteoglycans are key structural elements of extracellular matrix in the articular cartilage and synovium and are secreted as lubricants in the synovial fluid. Alterations of proteoglycans contribute to mechanism of disease in RA. Proteoglycans such as aggrecan can be citrullinated and become potential targets of the rheumatoid auto-immune response. Proteoglycans are also up-regulated in RA joints and/or undergo alterations of their regulatory functions over cytokines and chemokines, which promotes inflammation and bone damage. Recent studies have aimed to not only clarify these mechanisms but also develop novel proteoglycan-modulating therapeutics. These include agents altering the function and signaling of proteoglycans as well as tolerizing agents based on citrullinated aggrecan. This mini-review summarizes the most recent findings regarding the dysregulation of proteoglycans that contributes to RA pathogenesis and the potential for proteoglycan-modulating agents to improve RA therapy.

Serum syndecan-4 is associated with nonalcoholic fatty liver disease

OBJECTIVES

The accelerated shedding of extracellular domains of syndecan-4 (SDC4) is associated with central obesity and insulin resistance, while the association between serum SDC4 and nonalcoholic fatty liver disease (NAFLD) is unknown. We aimed to examine the association between SDC4 and NAFLD.

METHODS

Adults undergoing a health examination from 1 June 2019 to 31 December 2019 were enrolled. A diagnosis of NAFLD was made with an abdominal ultrasound. Logistic regression models and the receiver operating characteristic (ROC) curves were used to evaluate the role of SDC4 in predicting NAFLD.

RESULTS

In total, 533 eligible participants were finally enrolled, among them 157 (29.46%) had NAFLD. The proportion of patients with NAFLD increased with the increasing quartiles of serum SDC4. With the increase of serum SDC4 levels, metabolic features including waist circumference, serum triglyceride, total cholesterol, fasting blood glucose, fasting insulin and homeostasis model assessment of insulin resistance were significantly increased. SDC4 was an independent factor for NAFLD (odds ratio 1.963, 95% confidence interval [CI] 1.628-2.367, P < 0.001). The area under the ROC curve of SDC4 for predicting NAFLD was 0.934 (95% CI 0.910-0.959). The optimal cut-off value was 6.575 ng/mL at Youden's index of 0.767. SDC4 had the highest diagnostic sensitivity (84.1%), positive predictive value (82.5%), negative predictive value (93.3%) and positive likelihood ratio (11.356) among all the variables.

CONCLUSIONS

Elevated serum SDC4 level is associated with metabolic disorders and the prevalence of NAFLD among general population. Serum SDC4 may serve as a biomarker of NAFLD.

Destructive Roles of Fibroblast-like Synoviocytes in Chronic Inflammation and Joint Damage in Rheumatoid Arthritis

Fibroblast-like synoviocytes (FLSs) are important non-immune cells located mostly in the inner layer of the synovium. Indeed, these cells are specialized mesenchymal cells, implicated in collagen homeostasis of the articular joint and provide extracellular matrix (ECM) materials for cartilage and contribute to joint destruction via multiple mechanisms. RA FLS interactions with immune and non-immune cells lead to the development and organization of tertiary structures such as ectopic lymphoid-like structures (ELSs), tertiary lymphoid organs (TLOs), and secretion of proinflammatory cytokines. The interaction of RA FLS cells with immune and non-immune cells leads to stimulation and activation of effector immune cells. Pathological role of RA FLS cells has been reported for many years, while molecular and cellular mechanisms are not completely understood yet. In this review, we tried to summarize the latest findings about the role of FLS cells in ELS formation, joint destruction, interactions with immune and non-immune cells, as well as potential therapeutic options in rheumatoid arthritis (RA) treatment. Our study revealed data about interactions between RA FLS and immune/non-immune cells as well as the role of RA FLS cells in joint damage, ELS formation, and neoangiogenesis, which provide useful information for developing new approaches for RA treatment.

Syndecan 4 contributes to osteoclast differentiation induced by RANKL through enhancing autophagy

Periodontitis is a common chronic disease. Osteoclast differentiation contributes to alveolar bone resorption which is a distinct phenomenon during periodontitis. Syndecan 4 (SDC4), a member of the syndecan family, was found to be highly expressed during periodontitis. However, little is known about its role in periodontitis. Herein, we explored the role of SDC4 in osteoclast differentiation. An experimental periodontitis rat model was established by ligating the right first molar. The SDC4 expression in periodontium was detected by western blot and immunofluorescence. Our study demonstrated that SDC4 was highly expressed in the periodontium of periodontitis rats. It was positively transcriptionally regulated by NF-κB. SDC4 silencing abrogated osteoclast differentiation induced by RANKL, while SDC4 overexpression enhanced osteoclast differentiation. Moreover, SDC4 enhanced autophagy induced by RANKL. 3-MA, an autophagy inhibitor, was employed to explore whether SDC4 impacts osteoclast differentiation through activating autophagy. Treatment with 3-MA abolished osteoclast differentiation which was enhanced by SDC4, indicating that SDC4 promotes osteoclast differentiation through activating autophagy. This study reveals that SDC4 may contribute to osteoclast differentiation during periodontitis through activating autophagy. It sheds light on the important role of SDC4 in periodontitis.

Syndecan receptors: pericellular regulators in development and inflammatory disease

The syndecans are the major family of transmembrane proteoglycans, usually bearing multiple heparan sulfate chains. They are present on virtually all nucleated cells of vertebrates and are also present in invertebrates, indicative of a long evolutionary history. Genetic models in both vertebrates and invertebrates have shown that syndecans link to the actin cytoskeleton and can fine-tune cell adhesion, migration, junction formation, polarity and differentiation. Although often associated as co-receptors with other classes of receptors (e.g. integrins, growth factor and morphogen receptors), syndecans can nonetheless signal to the cytoplasm in discrete ways. Syndecan expression levels are upregulated in development, tissue repair and an array of human diseases, which has led to the increased appreciation that they may be important in pathogenesis not only as diagnostic or prognostic agents, but also as potential targets. Here, their functions in development and inflammatory diseases are summarized, including their potential roles as conduits for viral pathogen entry into cells.

Phenolic Compounds Impact on Rheumatoid Arthritis, Inflammatory Bowel Disease and Microbiota Modulation

Non-communicable chronic diseases (NCDs) are nowadays the principal cause of death, especially in most industrialized nations. These illnesses have increased exponentially with the consumption of diets very high in fat and sugar, not to mention stress and physical inactivity among other factors. The potential impact of suboptimal diets on NCDs’ morbidity and mortality rates brings to the forefront the necessity for a new way of improving dietary habits. The literature provides extensive scientific work that presents evidence that phenolic compounds from diets have antioxidant, anti-inflammatory and antiproliferative activities that impact human health. Gut microbiota modulation by some phenolic compounds leads to favorable changes in abundance, diversity, and in the immune system. However, polyphenol’s limited bioavailability needs to be overcome, highlighting their application in new delivery systems and providing their health benefits in well-established ways such as health maintenance, treatment or adjuvant to conventional pharmacological treatments. In this context, novel dietary approaches, including new food supplements, have emerged to prevent diseases and preserve health.

RAB5A is associated with genes involved in exosome secretion: Integration of bioinformatics analysis and experimental validation

Exosomes, as cell-cell communicators with an endosomal origin, are involved in the progression of various diseases. RAB5A, a member of the small Rab GTPases family, which is well known as a key regulator of cellular endocytosis, is expected to be involved in exosome secretion. Here, we found the impact of RAB5A on exosome secretion from human hepatocellular carcinoma cell line using a rapid yet reliable bioinformatics approach followed by experimental analysis. Initially, RAB5A and exosome secretion-related genes were gathered from bioinformatics tools, namely, CTD, COREMINE, and GeneMANIA; and published papers. Protein-protein interaction (PPI) was then constructed by the Search Tool for Retrieval of Interacting Genes (STRING) database. Among them, several genes with different combined scores were validated by the real-time quantitative polymerase chain reaction (RT-qPCR) in stable RAB5A knockdown cells. Thereafter, to validate the bioinformatics results functionally, the impact of RAB5A knockdown on exosome secretion was evaluated. Bioinformatics analysis showed that RAB5A interacts with 37 genes involved in exosome secretion regulatory pathways. Validation by RT-qPCR confirmed the association of RAB5A with candidate interacted genes and interestingly showed that even medium to low combined scores of the STRING database could be experimentally valid. Moreover, the functional analysis demonstrated that the stable silencing of RAB5A could experimentally decrease exosome secretion. In conclusion, we suggest RAB5A as a regulator of exosome secretion based on our bioinformatics approach and experimental analysis. Also, we propose the usage of PPI-derived from the STRING database regardless of their combined scores in advanced bioinformatics analysis.

Syndecan-4 is regulated by IL-1β in β-cells and human islets

Syndecans (SDC) are important multifunctional components of the extracellular matrix mainly described in endothelial cells. We studied the expression and regulation of SDC in cultured MIN6B1 cells and pancreatic islets. qRT-PCR revealed that syndecan-4 (SDC4) was the predominant isoform expressed in MIN6B1 cells and islets compared to other forms of SDC. Immunofluorescence in mouse and human pancreas sections revealed that SDC4 is mainly expressed in β-cells compared to other pancreatic cells. Exposure of MIN6B1 and human islets to IL-1β dose-dependently induced a rapid and transient expression of SDC4 while SRC and STAT3 inhibitors decreased this effect. Exposure of human islets to Il-1β caused an increase of SDC4 shedding, however treatment with STAT3 and SRC inhibitors inhibited this effect. These results indicate that SDC4 is upregulated by IL-1β through the SRC-STAT3 pathway and this pathway is also involved in SDC4 shedding in islets.

Proteoglycans in Obesity-Associated Metabolic Dysfunction and Meta-Inflammation

Proteoglycans are a specific subset of glycoproteins found at the cell surface and in the extracellular matrix, where they interact with a plethora of proteins involved in metabolic homeostasis and meta-inflammation. Over the last decade, new insights have emerged on the mechanism and biological significance of these interactions in the context of diet-induced disorders such as obesity and type-2 diabetes. Complications of energy metabolism drive most diet-induced metabolic disorders, which results in low-grade chronic inflammation, thereby affecting proper function of many vital organs involved in energy homeostasis, such as the brain, liver, kidney, heart and adipose tissue. Here, we discuss how heparan, chondroitin and keratan sulfate proteoglycans modulate obesity-induced metabolic dysfunction and low-grade inflammation that impact the initiation and progression of obesity-associated morbidities.