Cytokine signaling-1 suppressor is inducible by IL-1beta and inhibits the catabolic effects of IL-1beta in chondrocytes: its implication in the paradoxical joint-protective role of IL-1beta

The expression of SOCS1 is regulated by promoter DNA methylation and is associated with mitochondria-mediated apoptosis of T-2 induced chondrocytes

At present, the function of SOCS1 in Kashin-Beck disease (KBD) has not been reported. This study aims to explore the expression and mechanism of SOCS1 in KBD, and provide theoretical basis for the prevention and treatment of KBD. The expression of SOCS1 were measured by qRT-PCR and Western blot. ELISA was used to detect the content of SOCS1 in serum and synovial fluid. CCK-8 kits were selected to measure the cell viability. Methylation Specific PCR (MSP) assay is used to detect the methylation level of SOCS1 in chondrocytes. Flow cytometry was used to analyze the apoptosis rate of chondrocytes in different groups. The expression of apoptosis related proteins (caspase-3 and caspase-9) and Cytochrome c were detected using Western blot. The mitochondrial ROS, ATP and the activity of mitochondrial respiratory chain complexes were detected using commercial kits. The results showed that the expression of SOCS1 significantly increases in KBD patients and T-2 induced chondrocytes. Further research has found that the methylation levels of SOCS1 were significantly reduced in KBD patients and T-2 induced chondrocytes. Functional studies have found that SOCS1 silencing inhibited chondrocyte apoptosis and mitochondrial dysfunction. More importantly, SOCS1 regulated mitochondrial mediated chondrocyte apoptosis through the IGF-1/IGF-1R/FAK/Drp1 pathway. In conclusion, SOCS1 expression is increased and methylation levels are decreased in KBD, and is involved in regulating mitochondrial mediated apoptosis in T-2 induced chondrocytes through IGF-1/IGF-1R/FAK/Drp1 signaling. This study provides new theoretical basis for the treatment and prevention of KBD in clinical practice.

Sex Dimorphism in Pain Threshold and Neuroinflammatory Response: The Protective Effect of Female Sexual Hormones on Behavior and Seizures in an Allergic Rhinitis Model

Our previous research demonstrated that allergic rhinitis could impact behavior and seizure threshold in male mice. However, due to the complex hormonal cycles and hormonal influences on behavior in female mice, male mice are more commonly used for behavioral tests. In this study, we aimed to determine whether these findings were replicable in female mice and to explore the potential involvement of sexual hormones in regulating neuroinflammation in an allergic model. Our results indicate that pain threshold was decreased in female mice with allergic rhinitis and the levels of IL-23/IL-17A/IL-17R were increased in their Dorsal root ganglia. However, unlike males, female mice with AR did not display neuropsychological symptoms such as learning and memory deficits, depression, and anxiety-like behavior. This was along with decreased levels of DNA methyl transferase 1 (DNMT1) and inflammatory cytokines in their hippocampus. Ovariectomized mice were used to mitigate hormonal effects, and the results showed that they had behavioral changes and neuroinflammation in their hippocampus similar to male mice, as well as increased levels of DNMT1. These findings demonstrate sex differences in how allergic rhinitis affects behavior, pain sensitivity, and seizure thresholds. Furthermore, our data suggest that DNMT1 may be influenced by sexual hormones, which could play a role in modulating inflammation in allergic conditions.

Correlation of Womac Index and Cytokine Values in Patients with OA Knee

Osteoarthritis (OA) of the knee (gonarthrosis) is a degenerative rheumatic disease, which is the most common rheumatic disease. Numerous factors, such as mechanical, enzymatic, and biological, are responsible for the development of this complex, multifactorial disease. The connection between inflammation and the development of knee OA is being investigated more and more. Cytokines are thought to be one of the main causes of disturbances in normal cartilage metabolism.

This study, designed as a prospective cohort study included 60 patients with knee OA. The examinees were recruited from total population of patients with knee OA, hospitalized or treated as outpatients at Department of Physical Medicine and Rehabilitation, University Clinical Centre Kragujevac. After the consent was obtained, anamnestic data were collected, blood samples were taken and functional testing was done together with anthropometric measurements. The values of the following cytokines were determined from a blood sample: IL-6, TNF-α, IL-10, IL-17. The average age of patients was 69.10±9.06 years, most of whom were females (78,3%). Both IL-6 and TNF-α correlated positively with WOMAC scores. WOMAC index subscales showed different association with cytokines. In our studies the level of cytocines in the serum of pacients with OA knee is show not correlation with radiographic image.

The present study demonstrated than the concentrations of proinflammatory cytokines (TNF-α IL-6) can be correlated with WOMAC scores of knee OA patients. The results indicate that concentrations of TNF-α and IL-6 may affect knee joint function in patients with knee OA.

Potential Protective Role of Galectin-3 in Patients with Gonarthrosis and Diabetes Mellitus: A Cross-Sectional Study

BACKGROUND

Gonarthrosis and diabetes mellitus are two diseases that are increasingly being linked. The aim of this study was to quantify serum levels of Gal-3, pro- and anti-inflammatory cytokines (including their ratios and correlations), and participant's condition (pain, stiffness, functional limitations) in gonarthrosis patients with and without diabetes mellitus.

METHODS

A between-subject, cross-sectional experimental design was adopted. Serum levels of TNF-α, IL-6, IL-12, IL-23, IFN-γ, IL-17, IL-10, Gal-3, and WOMAC score were measured.

RESULTS

Gonarthrosis patients with diabetes mellitus had significantly (p < 0.05) lower levels of TNF-α, IL-6, IL-12, IL-17, IFN-γ, and Gal-3 compared to gonarthrosis patients without diabetes mellitus. On the other hand, IL-10/TNF-α, IL-10/IL-6, IL-10/IL-12, Gal-3/TNF-α, Gal-3/IL-6, and Gal-3/IL-12 (p = 0.001) were significantly higher (p < 0.05) in gonarthrosis with diabetes mellitus. Moderate-large correlation (p < 0.05) was detected between the serum values of Gal-3 and pro- and anti-inflammatory cytokines, including IL-12 (r = 0.575), IL-10 (r = 0.535), TNF-α (r = 0.306), and IL-23 (r = 0.323). WOMAC index was significantly lower (p < 0.05) in gonarthrosis patients without diabetes mellitus compared to gonarthrosis patients with diabetes mellitus.

CONCLUSIONS

Correlation between Gal-3 and proinflammatory cytokines and its dominance over proinflammatory cytokines implicate the potential role of Gal-3 in preventing cartilage destruction.

Circ_0134111 knockdown relieves IL-1β-induced apoptosis, inflammation and extracellular matrix degradation in human chondrocytes through the circ_0134111-miR-515-5p-SOCS1 network

BACKGROUND

Osteoarthritis (OA) is characterized by chondrocyte injury and dysfunction, such as excessive apoptosis, inflammatory response and extracellular matrix (ECM) degradation. Circular RNA (circRNA) deregulation is reported to be involved in OA. Our study aimed to explore the role of circ_0134111 in OA.

METHODS

Human chondrocytes were treated with interleukin-1β (IL-1β) to mimic OA cell model. The expression of circ_0134111, miR-515-5p and suppressor of cytokine signaling 1 (SOCS1) mRNA was measured by real-time quantitative polymerase chain reaction (RT-qPCR), and the protein levels of SOCS1 and apoptosis-/inflammation-/ECM-related markers were determined by western blot. Cell proliferation and cell apoptosis were assessed using cell counting kit-8 (CCK-8) and flow cytometry assay, respectively. For mechanism analysis, the predicted interaction between miR-515-5p and circ_0134111 or SOCS1 was verified by dual-luciferase reporter assay, pull-down assay and RNA immunoprecipitation (RIP) assay. Rescue experiments were performed to explore the interplay between miR-515-5p and circ_0134111 or SOCS1.

RESULTS

Circ_0134111 was overexpressed in OA cartilage tissues and IL-1β-induced chondrocytes. IL-1β-induced chondrocyte apoptosis, inflammatory responses and ECM degradation were alleviated by circ_0134111 knockdown or miR-515-5p restoration. Circ_0134111 acted as miR-515-5p sponge to regulate miR-515-5p expression, and miR-515-5p deficiency reversed the effects of circ_0134111 knockdown in IL-1β-induced chondrocytes. MiR-515-5p directly bound to SOCS1, and circ_0134111 decoyed miR-515-5p to increase SOCS1 level. MiR-515-5p restoration alleviated IL-1β-induced chondrocyte apoptosis, inflammatory responses and ECM degradation, While SOCS1 overexpression partly abolished these effects.

CONCLUSION

Circ_0134111 knockdown alleviated apoptosis, inflammatory responses and ECM degradation in OA cell model by mediating the miR-515-5p-SOCS1 network, hinting that circ_0134111 was involved in OA progression.

Estrogen downregulates TAK1 expression in human fibroblast-like synoviocytes and in a rheumatoid arthritis model

Transforming growth factor β-activated kinase-1 (TAK1), a member of the mitogen-activated protein kinase family, plays a key role in the pathogenesis and progression of rheumatoid arthritis (RA). Estrogen has been previously reported to delay arthritis progression. However, the exact association between TAK1 and estrogen remains elusive. The present study demonstrated that TAK1 was upregulated in synoviocytes of patients with RA compared with patients with osteoarthritis and healthy controls. In addition, TAK1 was also expressed in cultured fibroblast-like synoviocytes (FLS), and its levels decreased significantly in 17β-estradiol (E2)-treated cells in a dose-dependent manner. Furthermore, administration of E2 significantly decreased TAK1 expression and attenuated the development of collagen-induced arthritis (CIA). Taken together, the findings of the present study suggested that E2 mediates a decrease of TAK1 in both FLS and CIA, which subsequently results in a suppression of the pathological process of CIA. Therefore, estrogen may serve as a potential therapeutic agent for the treatment of RA by targeting TAK1.

Intra-articular xenogeneic mesenchymal stem cell-based therapy increases CD4+CD25+ cells in synovial fluid

Osteoarthritis (OA) is a chronic joint disease afflicting a substantial portion of the world's population with no currently available cure. Mesenchymal stem cell (MSC)-based therapies have been observed to have a mild beneficial effect in OA but the mechanism behind their action remains unclear. This study aimed to identify the lymphocytic response to a xenogeneic human umbilical cord-derived MSC-based cell therapy. A unilateral medial meniscal release model was employed in an ovine model of post-traumatic OA, with the contralateral limb employed as the control. A dose of 1.0 × 10⁷ MSCs was administered to a subset of the OA group as well as to a normal sham-operated group. Synovial fluid was aspirated periodically for 13 weeks for flow cytometry analysis. At the termination of the study the stifle joints were collected and analyzed for potential pathologic changes. Cell therapy induced a transient influx of CD4⁺ leukocytes; there was a similar significant increase in the proportion of CD4⁺CD25⁺ and CD4⁺CD25^hi leukocytes in response to cell therapy, the latter being a subset that may be composed of regulatory T cells. There was no significant effect of the cell therapy treatment on the proportion of synovial fluid-derived CD8⁺ cells or BAQ44A⁺ B cells. iNOS expression of intimal lining macrophages was evident but reduced in the cell therapy OA group suggesting macrophage phenotype transformation. There were no inflammatory or histological changes that could be attributed to the cell therapy. Cell therapy induced chemotaxis of CD4⁺ cells to the joint but these cells were not associated with pathological changes, despite their expression of activation markers (CD25⁺).

The role of indoleamine 2,3 dioxygenase 1 in the osteoarthritis

Osteoarthritis (OA) is a chronic degenerative joint disease and a leading cause of disability. It involves articular cartilage destruction and a whole joint inflammation. In spite of OA pathogenesis is still unclear, new studies on the OA pathophysiological aetiology and immunomodulation therapy continuously achieve significant advances with new concepts. Here, we focus on the indoleamine-2,3-dioxygenase1 (IDO1) activity in the osteoarthritis (OA), which is one of the noticeable enzymes in the synovial fluid of arthritis patients. It was recognized as an essential mediator of autoreactive B and T cell responses in rheumatoid arthritis (RA) and an interesting therapeutic target against RA. However, the role IDO1 plays in the OA pathogenesis hasn't been discussed. The new OA experimental analysis evidenced IDO1 overexpression in the synovial fluid of OA patients, and recent studies reported that IDO1 metabolites were found higher in the OA synovial fluid than RA and spondyloarthropathies (SpA) patients. Moreover, the positive relation of IDO1 metabolites with OA pain and joint stiffness has been confirmed. Thus, the IDO1 plays a pivotal role in the pathogenesis of OA. In this review, the role IDO1 plays in the OA pathogenesis has been deeply discussed. It could be a promising target in the immunotherapy of OA disease.

Identifying effector molecules, cells, and cytokines of innate immunity in OA

Inflammatory changes are observed in affected joints of osteoarthritis (OA) patients and are thought to be involved in the pathology that develops along OA progression. This narrative review provides an overview of the various cell types that are present in the joint during OA and which alarmins, cytokines, chemokines, growth factors, and other mediators they produce. Moreover, the involvement of more systemic processes like inflammaging and its associated cellular senescence in the context of OA are discussed.

NF-κB Signaling Pathways in Osteoarthritic Cartilage Destruction

Osteoarthritis (OA) is a type of joint disease associated with wear and tear, inflammation, and aging. Mechanical stress along with synovial inflammation promotes the degradation of the extracellular matrix in the cartilage, leading to the breakdown of joint cartilage. The nuclear factor-kappaB (NF-κB) transcription factor has long been recognized as a disease-contributing factor and, thus, has become a therapeutic target for OA. Because NF-κB is a versatile and multi-functional transcription factor involved in various biological processes, a comprehensive understanding of the functions or regulation of NF-κB in the OA pathology will aid in the development of targeted therapeutic strategies to protect the cartilage from OA damage and reduce the risk of potential side-effects. In this review, we discuss the roles of NF-κB in OA chondrocytes and related signaling pathways, including recent findings, to better understand pathological cartilage remodeling and provide potential therapeutic targets that can interfere with NF-κB signaling for OA treatment.

miR‑146a‑5p expression is upregulated by the CXCR4 antagonist TN14003 and attenuates SDF‑1‑induced cartilage degradation

Osteoarthritis (OA) is an aseptic inflammatory disease which is associated with the stromal cell-derived factor 1/C-X-C chemokine receptor type 4 (SDF-1/CXCR4) axis. Accumulating studies have identified numbers of microRNAs (miRNAs) that serve important roles in the pathogenesis of OA. However, whether and how the inhibition of the SDF-1/CXCR4 axis induces alterations in miRNA expression remains largely unclear. miRNA profiling was performed in OA chondrocytes stimulated with SDF-1 alone, or SDF-1 with the CXCR4 antagonist TN14003 by miRNA microarray. Candidate miRNAs were verified by reverse transcription quantitative polymerase chain reaction. Bioinformatic analyses including target prediction, gene ontology (GO) and pathway analysis were performed to explore the potential functions of candidate miRNAs. Notably, 7 miRNAs (miR-146a-5p, miR-221-3p, miR-126-3p, miR-185-5p, miR-155-5p, miR-124-3p and miR-130a-3p) were significantly differentially expressed. GO analysis indicated that miR-146a-5p and its associated genes were enriched in receptor regulatory activity, nuclear factor-kappa-light-chain-enhancer of activated B cells (NF-κB)-inducing kinase activity, cellular response to interleukin-1, cytokine-cytokine receptor interaction, NF-κB signaling pathway and osteoclast differentiation pathways. CXCR4 was predicted to be a target of miR-146a-5p with high importance. The mRNA and protein levels of key factors involved in cartilage degeneration were measured following manipulation of the expression levels of miR-146a-5p in OA chondrocytes. CXCR4 and MMP-3 levels were negatively associated with miR-146a-5p expression, while the levels of type II collagen and aggrecan were positively associated. These data reveal that TN14003 upregulates miR-146a-5p expression, and also pinpoints a novel role of miR-146a-5p in inhibiting cartilage degeneration by directly targeting the SDF-1/CXCR4 axis.

Systems biology reveals how altered TGFβ signalling with age reduces protection against pro-inflammatory stimuli

Osteoarthritis (OA) is a degenerative condition caused by dysregulation of multiple molecular signalling pathways. Such dysregulation results in damage to cartilage, a smooth and protective tissue that enables low friction articulation of synovial joints. Matrix metalloproteinases (MMPs), especially MMP-13, are key enzymes in the cleavage of type II collagen which is a vital component for cartilage integrity. Transforming growth factor beta (TGFβ) can protect against pro-inflammatory cytokine-mediated MMP expression. With age there is a change in the ratio of two TGFβ type I receptors (Alk1/Alk5), a shift that results in TGFβ losing its protective role in cartilage homeostasis. Instead, TGFβ promotes cartilage degradation which correlates with the spontaneous development of OA in murine models. However, the mechanism by which TGFβ protects against pro-inflammatory responses and how this changes with age has not been extensively studied. As TGFβ signalling is complex, we used systems biology to combine experimental and computational outputs to examine how the system changes with age. Experiments showed that the repressive effect of TGFβ on chondrocytes treated with a pro-inflammatory stimulus required Alk5. Computational modelling revealed two independent mechanisms were needed to explain the crosstalk between TGFβ and pro-inflammatory signalling pathways. A novel meta-analysis of microarray data from OA patient tissue was used to create a Cytoscape network representative of human OA and revealed the importance of inflammation. Combining the modelled genes with the microarray network provided a global overview into the crosstalk between the different signalling pathways involved in OA development. Our results provide further insights into the mechanisms that cause TGFβ signalling to change from a protective to a detrimental pathway in cartilage with ageing. Moreover, such a systems biology approach may enable restoration of the protective role of TGFβ as a potential therapy to prevent age-related loss of cartilage and the development of OA.

Effects of TLR-2/NF-κB signaling pathway on the occurrence of degenerative knee osteoarthritis: an in vivo and in vitro study

The study aims to explore the effects of TLR-2/NF-κB signaling pathway on the occurrence of degenerative knee osteoarthritis (OA). Degenerative knee OA and normal cartilage samples were collected from patients with degenerative knee OA receiving total knee arthroplasty and amputation. Expressions of TLR-2, NF-κB and MMP-13 were determined by qRT-PCR and immunochemistry. The chondrocytes were divided into control, IL-1β, IL-1β + anti-TLR-2 and IL-1β + PDTC groups. MTT assay and flow cytometry were performed to determine proliferation and apoptosis of the chondrocytes. Expressions of TLR-2, NF-κB and MMP-13 were measured by Western blotting. ELISA was conducted to detect the expressions of related inflammatory factors. The positive expressions of TLR, NF-κB and MMP13 were associated with body mass index (BMI), family history, exercise, and WOMAC scores of OA patients. Logistic regression analysis showed that OA influencing factors were TLR, NF-κB, MMP13, BMI, family history and exercise. Compared with normal chondrocytes, the expressions of TLR-2, NF-κB, MMP-13 and related inflammatory factors increased in degenerative knee OA. The chondrocytes in the IL-1β + anti-TLR-2 and IL-1β + PDTC groups showed lower apoptosis rates than those in the IL-1β group. Compared with the control group, increased expressions of TLR-2, NF-κB, phosphorylated-NF-κB (p-NF-κB), MMP-13, IL-1, IL-6 and TNF-α were found in the IL-1β group. In the IL-1β + anti-TLR-2 and IL-1β + PDTC groups, decreased expressions of NF-κB, p-NF-κB, MMP-13, IL-1, IL-6 and TNF-α were found compared with those in the IL-1β group. TLR-2/NF-κB signaling pathway contributes to the occurrence of degenerative knee OA.

Transforming growth factor β activated kinase 1: a potential therapeutic target for rheumatic diseases

Pro-inflammatory cytokines such as IL-1β, IL-6 and TNF-α are central regulators of autoinflammatory diseases. While targeting these cytokines has proven to be a successful clinical strategy, the long-term challenges such as drug resistance, lack of efficacy and poor clinical outcomes in some patients are some of the limitations faced by these therapies. This has ignited strategies to reduce inflammation by potentially targeting a variety of molecules, including cell surface receptors, signalling proteins and/or transcription factors to minimize cytokine-induced inflammation and tissue injury. In this regard, transforming growth factor β activated kinase 1 (TAK1) is activated in the inflammatory signal transduction pathways in response to IL-1β, TNF-α or toll-like receptor stimulation. Because of its ideal position upstream of mitogen-activated protein kinases and the IκB kinase complex in signalling cascades, targeting TAK1 may be an attractive strategy for treating diseases characterized by chronic inflammation. Here, we discuss the emerging role of TAK1 in mediating the IL-1β, TNF-α and toll-like receptor mediated inflammatory responses in diseases such as RA, OA, gout and SS. We also review evidence suggesting that TAK1 inhibition may have potential therapeutic value. Finally, we focus on the current status of the development of TAK1 inhibitors and suggest further opportunities for testing TAK1 inhibitors in rheumatic diseases.

SOCS1 Regulates Apoptosis and Inflammation by Inhibiting IL-4 Signaling in IL-1β-Stimulated Human Osteoarthritic Chondrocytes

Recently, Suppressor of Cytokine Signaling 1 (SOCS1) was identified as a potential therapeutic target for osteoarthritis (OA) treatment. However, the mechanisms and signaling pathways of SOCS1 in the regulation of OA development are unclear. The purpose of the current study was to investigate whether interleukin- (IL-) 4 was involved in regulatory mechanism of SOCS1 in human osteoarthritic chondrocytes. First, IL-1β was used to stimulate human osteoarthritic chondrocytes isolated from the articular cartilage of OA patients undergoing total knee replacement. The protein and mRNA expression levels of SOCS1 were upregulated in IL-1β-stimulated human osteoarthritic chondrocytes compared with control cells. The knockdown of SOCS1 increased cell viability and inhibited cell apoptosis. It was also found that IL-4 expression was increased by SOCS1 silencing. Additionally, knockdown of IL-4 reduced cell viability and increased cell apoptosis of osteoarthritic chondrocytes transfected with SOCS1 siRNA. Moreover, the decreased expression of inflammatory factors induced by SOCS1 was enhanced by IL-4 knockdown. In conclusion, IL-4 signaling plays a crucial role in the regulatory functions of SOCS1 in apoptosis and inflammation in human osteoarthritic chondrocytes. These findings provide a potential therapeutic target for the clinical treatment of OA.

SOCS1 suppresses IL-1β-induced C/EBPβ expression via transcriptional regulation in human chondrocytes

CAAT/enhancer-binding protein-beta (C/EBPβ) is a transcription factor that regulates interleukin-1β (IL-1β)-induced catabolic pathways, including the expression of matrix metalloproteinases (MMPs), in chondrocytes. We previously reported that suppressor of cytokine signaling 1 (SOCS1) inhibits IL-1β signaling in chondrocytes. However, the effect of SOCS1 on C/EBPβ has not been explored. To investigate the interaction between SOCS1 and C/EBPβ, we established human SW1353 cells with overexpression or knockdown of SOCS1 or C/EBPβ. Both SOCS1 and C/EBPβ were involved in transcription of MMP-3 and MMP-13. When stimulated with IL-1β, C/EBPβ levels were significantly increased by SOCS1 knockdown and decreased by SOCS1 overexpression. A similar change in IL-1β-induced C/EBPβ expression was observed in SOCS1-transfected human articular chondrocytes. However, C/EBPβ overexpression or knockdown did not change the levels of IL-1β-induced SOCS1. SOCS1 regulated the levels of C/EBPβ mRNA by ubiquitination of C/EBPβ as well as transcriptional regulation. Furthermore, it suppressed the phosphorylation of cAMP response element-binding protein (CREB), an active transcription factor of C/EBPβ. In addition, p38 mitogen-activated protein kinases, a target of SOCS1, was involved in CREB phosphorylation. The chromatin immunoprecipitation assay confirmed that SOCS1 overexpression led to reduced binding of C/EBPβ to the MMP-13 promoter. Taken together, our results demonstrate that SOCS1 downregulates the p38-CREB-C/EBPβ pathway resulting in increased expression of MMPs in chondrocytes.

Altered signaling in systemic juvenile idiopathic arthritis monocytes

Systemic juvenile idiopathic arthritis (sJIA) is characterized by systemic inflammation and arthritis. Monocytes are implicated in sJIA pathogenesis, but their role in disease is unclear. The response of sJIA monocytes to IFN may be dysregulated. We examined intracellular signaling in response to IFN type I (IFNα) and type II (IFNγ) in monocytes during sJIA activity and quiescence, in 2 patient groups. Independent of disease activity, monocytes from Group 1 (collected between 2002 and 2009) showed defective STAT1 phosphorylation downstream of IFNs, and expressed higher transcript levels of SOCS1, an inhibitor of IFN signaling. In the Group 2 (collected between 2011 and 2014), monocytes of patients with recent disease onset were IFNγ hyporesponsive, but in treated, quiescent subjects, monocytes were hyperresponsive to IFNγ. Recent changes in medication in sJIA may alter the IFN hyporesponsiveness. Impaired IFN/pSTAT1 signaling is consistent with skewing of sJIA monocytes away from an M1 phenotype and may contribute to disease pathology.

Galectins regulate the inflammatory response in airway epithelial cells exposed to microbial neuraminidase by modulating the expression of SOCS1 and RIG1

Influenza patients frequently display increased susceptibility to Streptococcus pneumoniae co-infection and sepsis, the prevalent cause of mortality during influenza pandemics. However, the detailed mechanisms by which an influenza infection predisposes patients to suffer pneumococcal pneumonia are not fully understood. A murine model for influenza infection closely reflects the observations in human patients, since if the animals that have recovered from influenza A virus (IAV) sublethal infection are challenged with S. pneumoniae, they undergo a usually fatal uncontrolled cytokine response. We have previously demonstrated both in vitro and in vivo that the expression and secretion of galectin-1 (Gal1) and galectin-3 (Gal3) are modulated during IAV infection, and that the viral neuraminidase unmasks galactosyl moieties in the airway epithelia. In this study we demonstrate in vitro that the binding of secreted Gal1 and Gal3 to the epithelial cell surface modulates the expression of SOCS1 and RIG1, and activation of ERK, AKT or JAK/STAT1 signaling pathways, leading to a disregulated expression and release of pro-inflammatory cytokines. Our results suggest that the activity of the viral and pneumococcal neuraminidases on the surface of the airway epithelial cells function as a "danger signal" that leads to rapid upregulation of SOCS1 expression to prevent an uncontrolled inflammatory response. The binding of extracellular Gal1 or Gal3 to the galactosyl moieties unmasked on the surface of airway epithelial cells can either "fine-tune" or severely disregulate this process, respectively, the latter potentially leading to hypercytokinemia.

Effects of icariin on the regulation of the OPG-RANKL-RANK system are mediated through the MAPK pathways in IL-1β-stimulated human SW1353 chondrosarcoma cells

Arthrodial cartilage degradation and subchondral bone remodeling comprise the most predominant pathological changes in osteoarthritis (OA). Moreover, accumulating evidence indicates that the abnormal expression of osteoprotegerin (OPG), receptor activator of nuclear factor kappa-B ligand (RANKL) and receptor activator of nuclear factor kappa-B (RANK) plays a vital role in the collapse of cartilage and subchondral bone. In the present study, the effects of icariin on the expression levels of these 3 factors in interleukin (IL)-1β-stimulated SW1353 chondrosarcoma cells were investigated. The SW1353 chondrosarcoma cells were cultured in the presence or absence of icariin and mitogen-activated protein kinase signaling pathway inhibitors, and were then stimulated with IL-1β. Cell viability was assessed by MTT assay. The mRNA and protein expression of OPG, RANKL and RANK was analyzed by quantitative reverse transcription polymerase chain reaction (RT-qPCR) and ELISA, respectively. In addition, the levels of phosphorylated p38 (p-p38) and phosphorylated extracellular signal-regulated kinase (p-ERK)1/2 were detected by western blot analysis. The results from western blot analysis revealed that treatment with icariin decreased the levels of p-p38 and increased the levels of p-ERK1/2 in the IL-1β-stimulated SW1353 cells. In addition, treatment with icariin decreased the levels of RANK and RANKL. Furthermore, the suppressive effects of icariin on OPG and OPG/RANKL were greater than those exhibited by the p38 signaling pathway inhibitor (SB203580). The findings of the the present study suggest that icariin has therapeutic potential for use in the treatment of OA.