Interleukin 17 regulates SHP-2 and IL-17RA/STAT-3 dependent Cyr61, IL-23 and GM-CSF expression and RANKL mediated osteoclastogenesis by fibroblast-like synoviocytes in rheumatoid arthritis

Ziyuglycoside II attenuated OVX mice bone loss via inflammatory responses and regulation of gut microbiota and SCFAs

BACKGROUND AND PURPOSE

Osteoporosis (OP) is a frequent clinical problem for the elderly. Traditional Chinese Medicine (TCM) has achieved beneficial results in the treatment of OP. Ziyuglycoside II (ZGS II) is a major active compound of Sanguisorba officinalis L. that has shown anti-inflammation and antioxidation properties, but little information concerning its anti-OP potential is available. Our research aims to investigate the mechanism of ZGS II in ameliorating bone loss by inflammatory responses and regulation of gut microbiota and short chain fatty acids (SCFAs) in ovariectomized (OVX) mice.

METHODS

We predicted the mode of ZGS II action on OP through network pharmacology and molecular docking, and an OVX mouse model was employed to validate its anti-OP efficacy. Then we analyzed its impact on bone microstructure, the levels of inflammatory cytokines and pain mediators in serum, inflammation in colon, intestinal barrier, gut microbiota composition and SCFAs in feces.

RESULTS

Network pharmacology identified 55 intersecting targets of ZGS II related to OP. Of these, we predicted IGF1 may be the core target, which was successfully docked with ZGS II and showed excellent binding ability. Our in vivo results showed that ZGS II alleviated bone loss in OVX mice, attenuated systemic inflammation, enhanced intestinal barrier, reduced the pain threshold, modulated the abundance of gut microbiota involving norank_f__Muribaculaceae and Dubosiella, and increased the content of acetic acid and propanoic acid in SCFAs.

CONCLUSIONS

Our data indicated that ZGS II attenuated bone loss in OVX mice by relieving inflammation and regulating gut microbiota and SCFAs.

Interplay between mesenchymal stem cells and macrophages: Promoting bone tissue repair

The repair of bone tissue damage is a complex process that is well-orchestrated in time and space, a focus and difficulty in orthopedic treatment. In recent years, the success of mesenchymal stem cells (MSCs)-mediated bone repair in clinical trials of large-area bone defects and bone necrosis has made it a candidate in bone tissue repair engineering and regenerative medicine. MSCs are closely related to macrophages. On one hand, MSCs regulate the immune regulatory function by influencing macrophages proliferation, infiltration, and phenotype polarization, while also affecting the osteoclasts differentiation of macrophages. On the other hand, macrophages activate MSCs and mediate the multilineage differentiation of MSCs by regulating the immune microenvironment. The cross-talk between MSCs and macrophages plays a crucial role in regulating the immune system and in promoting tissue regeneration. Making full use of the relationship between MSCs and macrophages will enhance the efficacy of MSCs therapy in bone tissue repair, and will also provide a reference for further application of MSCs in other diseases.

Dual drug nanoparticle synergistically induced apoptosis, suppressed inflammation, and protected autophagic response in rheumatoid arthritis fibroblast-like synoviocytes

Rheumatoid arthritis (RA) is a chronic immune-mediated joint inflammatory disorder associated with aberrant activation of fibroblast-like synoviocytes (FLS). Recently, FLS gained importance due to its crucial role in RA pathogenesis, and thus, targeting FLS is suggested as an attractive treatment strategy for RA. FLS-targeted approaches may be combined with disease-modifying antirheumatic drugs (DMARDs) and natural phytochemicals to improve efficacy in RA control and negate immunosuppression. In this study, we assessed the therapeutic effectiveness of DD NP HG in primary RA-FLS cells isolated from the synovial tissue of FCA-induced RA rats. We observed that DD NP HG had good biosafety for healthy FLS cells and, at higher concentrations, a mild inhibitory effect on RA-FLS. The combination therapy (DD NP HG) of MTX NP and PEITC NE in RA-FLS showed a higher rate of apoptosis with significantly reduced LPS-induced expression of pro-inflammatory cytokines (TNF-α, IL-17A, and IL-6) in arthritic FLS. Further, the gene expression studies showed that DD NP HG significantly down-regulated the mRNA expression of IL-1β, RANKL, NFATc1, DKK1, Bcl-xl, Mcl-1, Atg12, and ULK1, and up-regulated the mRNA expression of OPG, PUMA, NOXA and SQSTM1 in LPS-stimulated RA-FLS cells. Collectively, our results demonstrated that DD NP HG significantly inhibited the RA-FLS proliferation via inducing apoptosis, down-regulating pro-inflammatory cytokines, and further enhancing the expression of genes associated with bone destruction in RA pathogenesis. A nanotechnology approach is a promising strategy for the co-delivery of dual drugs to regulate the RA-FLS function and achieve synergistic treatment of RA.

Exosomal Osteoclast-Derived miRNA in Rheumatoid Arthritis: From Their Pathogenesis in Bone Erosion to New Therapeutic Approaches

Rheumatoid arthritis (RA) is an autoimmune disease that causes inflammation, pain, and ultimately, bone erosion of the joints. The causes of this disease are multifactorial, including genetic factors, such as the presence of the human leukocyte antigen (HLA)-DRB1*04 variant, alterations in the microbiota, or immune factors including increased cytotoxic T lymphocytes (CTLs), neutrophils, or elevated M1 macrophages which, taken together, produce high levels of pro-inflammatory cytokines. In this review, we focused on the function exerted by osteoclasts on osteoblasts and other osteoclasts by means of the release of exosomal microRNAs (miRNAs). Based on a thorough revision, we classified these molecules into three categories according to their function: osteoclast inhibitors (miR-23a, miR-29b, and miR-214), osteoblast inhibitors (miR-22-3p, miR-26a, miR-27a, miR-29a, miR-125b, and miR-146a), and osteoblast enhancers (miR-20a, miR-34a, miR-96, miR-106a, miR-142, miR-199a, miR-324, and miR-486b). Finally, we analyzed potential therapeutic targets of these exosomal miRNAs, such as the use of antagomiRs, blockmiRs, agomiRs and competitive endogenous RNAs (ceRNAs), which are already being tested in murine and ex vivo models of RA. These strategies might have an important role in reestablishing the regulation of osteoclast and osteoblast differentiation making progress in the development of personalized medicine.

Relationship between SHP2 gene polymorphisms and systemic lupus erythematosus risk

OBJECTIVE

Systemic lupus erythematosus (SLE) is a complex autoimmune disorder. SHP2, a non-transmembrane member of the protein tyrosine phosphatase (PTP) family, can be involved in multiple signaling pathways in inflammatory response. To date, it remains to be investigated whether polymorphisms in the SHP2 gene are correlated with SLE in the Chinese Han population.

METHOD

A study comprising 320 SLE patients and 400 healthy individuals was performed. Three single nucleotide polymorphisms (rs4767860, rs7132778, rs7953150) of the SHP2 gene were genotyped using the Kompetitive Allele-Specific Polymerase Chain Reaction method.

RESULTS

Genotypes of rs4767860 (AA, AG + AA) and rs7132778 (AA, AC + AA), and alleles of rs4767860 (A) and rs7132778 (A) were associated with SLE risk. Genotype AA of rs7132778 and allele A of rs7132778 and rs7953150 were associated with oral ulcers in SLE patients. Allele C of rs7132778 and genotype AA and allele A of rs7953150 were associated with pyuria. Patients who carried AA genotype and allele A of rs7953150 are more likely to develop hypocomplementemia. AA and AG genotype frequencies are more raised in patients with SLE with alopecia than in those without alopecia. Patients who carried AA and AG genotypes of rs4767860 had elevated C-reactive protein levels.

CONCLUSION

Gene polymorphisms of SHP2 (rs4767860, rs7132778) are relevant to SLE susceptibility.

SHP2: its association and roles in systemic lupus erythematosus

OBJECTIVE

Systemic lupus erythematosus (SLE) is an autoimmune inflammatory disease. Src homology 2 domain containing protein tyrosine phosphatase (SHP2) is a member of the protein tyrosine phosphatases (PTPs) family. To date, relationship between SHP2 and SLE pathogenesis is not elucidated.

METHOD

We measured plasma levels of SHP2 in 328 SLE patients, 78 RA patients, 80 SS patients and 79 healthy controls by ELISA, and discussed association of SHP2 in SLE patients, potential of plasma SHP2 as a SLE biomarker. Moreover, histological and serological changes were evaluated by flow cytometry, HE/Masson examination, immunofluorescence test in pristane-induced lupus mice after SHP2 inhibitor injection to reveal role of SHP2 in lupus development.

RESULTS

Results indicated that SHP2 plasma levels were upregulated in SLE patients and correlated with some clinical, laboratory characteristics such as proteinuria, pyuria, and may be a potential biomarker for SLE. After SHP2 inhibitor treatment, hepatosplenomegaly and histological severity of the kidney in lupus mice were improved. SHP2 inhibitor reversed DCs, Th1, and Th17 cells differentiation and downregulated inflammatory cytokines (IL-4, IL-6, IL-10, IL-17A, IFN-γ and TNF-α) and autoantibodies (ANA, anti-dsDNA) production in pristane-lupus mice.

CONCLUSION

In summary, SHP2 correlated with SLE pathogenesis and promoted the development of lupus.

Immune activation of characteristic gut mycobiota Kazachstania pintolopesii on IL-23/IL-17R signaling in ankylosing spondylitis

It is very important to understand the communication and interaction mechanisms between the host and its resident microorganisms on host physiology and for precise diagnosis and treatment. Although intestinal fungi and bacteria dysbiosis is increasingly linked to ankylosing spondylitis (AS), their mechanisms of action have been rarely illustrated. In this paper, fecal samples from 10 AS monkeys and 10 healthy controls were collected to systematically characterize the gut mycobiota and microbiota in AS monkeys by 16S rRNA and ITS2 DNA sequencing. Our results showed the gut fungi of Kazachstania pintolopesii, Saccharomycetaceae, Kazachstania, and Saccharomyceteles. Saccharomycetes were specially enriched in AS, and the microbiota of AS monkeys was characterized by an increased abundance of Clostridia, Clostridiales, Ruminococcaceae, and Prevotella 2, using Line Discriminant Analysis Effect Size. Compared to healthy controls, decreased ITS2/16S biodiversity ratios and altered bacterial-fungal interkingdom networks were observed in AS monkeys. Oral administration of K. pintolopesii activates IL-17RA pathway and induce inflammatory reaction in the colonic tissue of C57BL/6 mice, as well as multiple AS phenotypes, including fungal and bacterial dysbiosis, immune responses of NK cells, platelets, T cells, leukocytes, B-cell activation, rheumatoid arthritis, and inflammatory bowel disease. We also found the secreted products of K. pintolopesii could activate the IL-17RA pathway, which induces PANoptosis in macrophage RAW264.7 cells. Much worse, the PANoptosis products could promote the proliferation and morphological changes of K. pintolopesii, which resulted in much more K. pintolopesii and a severe inflammatory reaction. Interestingly, the inflammatory factor TNF-α can promote the morphological transformation of Candida albicans and K. pintolopesii, which is worthy of further study. The characteristic fungi in all these findings implied that fungal and bacterial dysbiosis have a close link to AS and that their communication and interaction indeed play an important role in autoimmune responses, and K. pintolopesii could be a potential marker microorganism in AS, although its specific mechanism is not fully elucidated.

Pathomechanisms of bone loss in rheumatoid arthritis

Rheumatoid arthritis (RA) is an autoimmune disease, in which the inflammatory processes involve the skeletal system and there is marked destruction of the bones and the surrounding structures. In this review, we discuss the current concepts of osteoimmunology in RA, which represent the molecular crosstalk between the immune and skeletal systems, resulting in the disruption of bone remodeling. Bone loss in RA can be focal or generalized, leading to secondary osteoporosis. We have summarized the recent studies of bone loss in RA, which focused on the molecular aspects, such as cytokines, autoantibodies, receptor activator of nuclear kappa-β ligand (RANKL) and osteoprotegerin (OPG). Apart from the above molecules, the role of aryl hydrocarbon receptor (Ahr), which is a potential key mediator in this process through the generation of the Th17 cells, is discussed. Hence, this review highlights the key insights into molecular mechanisms of bone loss in RA.

Migration and homeostasis of regulatory T cells in rheumatoid arthritis

Regulatory T (T_reg) cells are garnering increased attention in research related to autoimmune diseases, including rheumatoid arthritis (RA). They play an essential role in the maintenance of immune homeostasis by restricting effector T cell activity. Reduced functions and frequencies of T_reg cells contribute to the pathogenesis of RA, a common autoimmune disease which leads to systemic inflammation and erosive joint destruction. T_reg cells from patients with RA are characterized by impaired functions and by an altered phenotype. They show increased plasticity towards Th17 cells and a reduced suppressive capacity. Besides the suppressive function of T_reg cells, their effectiveness is determined by their ability to migrate into inflamed tissues. In the past years, new mechanisms involved in T_reg cell migration have been identified. One example of such a mechanism is the phosphorylation of vasodilator-stimulated phosphoprotein (VASP). Efficient migration of T_reg cells requires the presence of VASP. IL-6, a cytokine which is abundantly present in the peripheral blood and in the synovial tissue of RA patients, induces posttranslational modifications of VASP. Recently, it has been shown in mice with collagen-induced arthritis (CIA) that this IL-6 mediated posttranslational modification leads to reduced T_reg cell trafficking. Another protein which facilitates T_reg cell migration is G-protein-signaling modulator 2 (GPSM2). It modulates G-protein coupled receptor functioning, thereby altering the cellular activity initiated by cell surface receptors in response to extracellular signals. The almost complete lack of GPSM2 in T_reg cells from RA patients contributes to their reduced ability to migrate towards inflammatory sites. In this review article, we highlight the newly identified mechanisms of T_reg cell migration and review the current knowledge about impaired T_reg cell homeostasis in RA.

The protective capability of Hedyotis diffusa Willd on lupus nephritis by attenuating the IL-17 expression in MRL/lpr mice

Lupus nephritis (LN), the most severe organ manifestation of systemic lupus erythematosus (SLE), is generally treated with glucocorticoids (GC) in clinical practice, leading to drug resistance and adverse effects in the long term. Fortunately, the combination of GC and traditional Chinese medical prescriptions can attenuate the adverse effects and improve therapeutic efficiency. Hedyotis diffusa Willd (HDW) is one of the most commonly used herbal compounds for LN treatment, which exhibits “heat-clearing” and “detoxification” effects. However, the underlying pharmacological mechanism remains unclear. The present study identified the chemical compounds in HDW extract with UPLC-Q-TOF-MS/MS. A total of 49 components were identified in the HDW extract, and the IL-17 signaling pathway was highly enriched by network pharmacological analysis. MRL/lpr model mice, reflecting the spontaneous development of LN, were used to evaluate the protective activity and investigate the underlying mechanism of the combination treatment. The white blood cell content (WBC), including lymphocytes and neutrophils, cytokines (IL-6, MCP-1, TNF-a), and various autoantibodies (ANA, ab-dsDNA, ab-snRNP/sm) in the blood of MRL/lpr mice were significantly improved by the intragastric administration of HDW. Additionally, the expression of STAT3, IL-17, Ly6G, and MPO in the kidney and neutrophil NETosis were ameliorated with HDW treatment. The pathological and morphological analysis suggested that HDW application could reduce urinary protein levels and inflammatory cell infiltration and inhibit glomerular interstitial cell proliferation. Hence, HDW might ameliorate lupus nephritis by inhibiting IL-6 secretion and STAT3-induced IL-17 expression. The active compounds in HDW were predictively selected with computational methods. The docking affinity of asiatic acid, neoandrographolide to IL-6, glycyrrhetinic acid, oleanolic acid, ursolic acid, and wilforlide A to STAT3 are extremely high. In conclusion, the IL-6 and STAT3/IL-17signaling pathways could be critical regulative targets of HDW on LN.

Targeting protein phosphatases for the treatment of inflammation-related diseases: From signaling to therapy

Inflammation is the common pathological basis of autoimmune diseases, metabolic diseases, malignant tumors, and other major chronic diseases. Inflammation plays an important role in tissue homeostasis. On one hand, inflammation can sense changes in the tissue environment, induce imbalance of tissue homeostasis, and cause tissue damage. On the other hand, inflammation can also initiate tissue damage repair and maintain normal tissue function by resolving injury and restoring homeostasis. These opposing functions emphasize the significance of accurate regulation of inflammatory homeostasis to ameliorate inflammation-related diseases. Potential mechanisms involve protein phosphorylation modifications by kinases and phosphatases, which have a crucial role in inflammatory homeostasis. The mechanisms by which many kinases resolve inflammation have been well reviewed, whereas a systematic summary of the functions of protein phosphatases in regulating inflammatory homeostasis is lacking. The molecular knowledge of protein phosphatases, and especially the unique biochemical traits of each family member, will be of critical importance for developing drugs that target phosphatases. Here, we provide a comprehensive summary of the structure, the "double-edged sword" function, and the extensive signaling pathways of all protein phosphatases in inflammation-related diseases, as well as their potential inhibitors or activators that can be used in therapeutic interventions in preclinical or clinical trials. We provide an integrated perspective on the current understanding of all the protein phosphatases associated with inflammation-related diseases, with the aim of facilitating the development of drugs that target protein phosphatases for the treatment of inflammation-related diseases.

Targeting macrophagic SHP2 for ameliorating osteoarthritis via TLR signaling

Osteoarthritis (OA), in which M1 macrophage polarization in the synovium exacerbates disease progression, is a major cause of cartilage degeneration and functional disabilities. Therapeutic strategies of OA designed to interfere with the polarization of macrophages have rarely been reported. Here, we report that SHP099, as an allosteric inhibitor of src-homology 2-containing protein tyrosine phosphatase 2 (SHP2), attenuated osteoarthritis progression by inhibiting M1 macrophage polarization. We demonstrated that M1 macrophage polarization was accompanied by the overexpression of SHP2 in the synovial tissues of OA patients and OA model mice. Compared to wild-type (WT) mice, myeloid lineage conditional Shp2 knockout (cKO) mice showed decreased M1 macrophage polarization and attenuated severity of synovitis, an elevated expression of cartilage phenotype protein collagen II (COL2), and a decreased expression of cartilage degradation markers collagen X (COL10) and matrix metalloproteinase 3 (MMP3) in OA cartilage. Further mechanistic analysis showed thatSHP099 inhibited lipopolysaccharide (LPS)-induced Toll-like receptor (TLR) signaling mediated by nuclear factor kappa B (NF-κB) and PI3K–AKT signaling. Moreover, intra-articular injection of SHP099 also significantly attenuated OA progression, including joint synovitis and cartilage damage. These results indicated that allosteric inhibition of SHP2 might be a promising therapeutic strategy for the treatment of OA.

LTF Regulates the Immune Microenvironment of Prostate Cancer Through JAK/STAT3 Pathway

Background

The study of the immune microenvironment in prostate cancer (PRAD) has brought new opportunities for the current traditional treatment regimens. Therefore, our goal is to develop a universal immunodiagnostic marker to improve patient survival.

Methods

Bioinformatics analysis: We collected 591 samples from The Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO) cohorts and evaluated the abundance and distribution of immune cell members in the PRAD expression profile matrix in the mixed cell population by CIBERSORT, ESTIMATE, single-sample gene set enrichment analysis (ssGSEA), and other methods. The target genes related to PRAD immune microenvironment and tumor mutation load were obtained by overlap analysis and verified by pan-cancer analysis. Cell experiment: The cell transfection scheme was designed, and the experiment was divided into three groups: overexpressing lactoferrin (LTF) group, empty plasmid group, and control group. After obtaining cells in each group, the gene and protein expression levels of LTF and signal transduction of signal transducer and activator of transcription 3 (STAT3) and granulocyte-macrophage colony-stimulating factor (GM-CSF) in the above three groups were detected by real-time PCR and Western blot, respectively. Finally, the level of GM-CSF secretion in the three groups was detected by ELISA.

Results

Macrophages, resting mast cells, and plasma cells play an important role in PRAD immune microenvironment. In addition, high tumor mutation load [tumor mutational burden (TMB)] was positively correlated with lymph node metastasis in patients with PRAD. As the core gene of the PRAD immune microenvironment, the low expression of LTF in PRAD promotes the occurrence of immunodeficiency, PRAD, and the enrichment of the Janus kinase (JAK)/STAT3 signal pathway. Through cell experiments, it was found that the content of LTF mRNA and protein increased significantly, while the content of STAT3 and GM-CSF mRNA and protein decreased significantly in the overexpressed LTF group. The level of GM-CSF in the supernatant of cell culture was significantly decreased in the overexpression group of LTF.

Conclusion

The core gene we proposed is one of the most promising biomarkers to improve the overall survival rate of PRAD and provides an important theoretical basis for the study of the mechanism of the LTF-mediated JAK/STAT3 pathway in PRAD.

Epigenetic drug development for autoimmune and inflammatory diseases

ES-62 is the major secreted protein of the parasitic filarial nematode, Acanthocheilonema viteae. The molecule exists as a large tetramer (MW, ~240kD), which possesses immunomodulatory properties by virtue of multiple phosphorylcholine (PC) moieties attached to N-type glycans. By suppressing inflammatory immune responses, ES-62 can prevent disease development in certain mouse models of allergic and autoimmune conditions, including joint pathology in collagen-induced arthritis (CIA), a model of rheumatoid arthritis (RA). Such protection is associated with functional suppression of "pathogenic" hyper-responsive synovial fibroblasts (SFs), which exhibit an aggressive inflammatory and bone-damaging phenotype induced by their epigenetic rewiring in response to the inflammatory microenvironment of the arthritic joint. Critically, exposure to ES-62 in vivo induces a stably-imprinted CIA-SF phenotype that exhibits functional responses more typical of healthy, Naïve-SFs. Consistent with this, ES-62 "rewiring" of SFs away from the hyper-responsive phenotype is associated with suppression of ERK activation, STAT3 activation and miR-155 upregulation, signals widely associated with SF pathogenesis. Surprisingly however, DNA methylome analysis of Naïve-, CIA- and ES-62-CIA-SF cohorts reveals that rather than simply preventing pathogenic rewiring of SFs, ES-62 induces further changes in DNA methylation under the inflammatory conditions pertaining in the inflamed joint, including targeting genes associated with ciliogenesis, to programme a novel "resolving" CIA-SF phenotype. In addition to introducing a previously unsuspected aspect of ES-62's mechanism of action, such unique behaviour signposts the potential for developing DNA methylation signatures predictive of pathogenesis and its resolution and hence, candidate mechanisms by which novel therapeutic interventions could prevent SFs from perpetuating joint inflammation and destruction in RA. Pertinent to these translational aspects of ES-62-behavior, small molecule analogues (SMAs) based on ES-62's active PC-moieties mimic the rewiring of SFs as well as the protection against joint disease in CIA afforded by the parasitic worm product.

Cytokine Networks in the Pathogenesis of Rheumatoid Arthritis

Rheumatoid arthritis (RA) is an autoimmune disease characterized by chronic systemic inflammation causing progressive joint damage that can lead to lifelong disability. The pathogenesis of RA involves a complex network of various cytokines and cells that trigger synovial cell proliferation and cause damage to both cartilage and bone. Involvement of the cytokines tumor necrosis factor (TNF)-α and interleukin (IL)-6 is central to the pathogenesis of RA, but recent research has revealed that other cytokines such as IL-7, IL-17, IL-21, IL-23, granulocyte macrophage colony-stimulating factor (GM-CSF), IL-1β, IL-18, IL-33, and IL-2 also play a role. Clarification of RA pathology has led to the development of therapeutic agents such as biological disease-modifying anti-rheumatic drugs (DMARDs) and Janus kinase (JAK) inhibitors, and further details of the immunological background to RA are emerging. This review covers existing knowledge regarding the roles of cytokines, related immune cells and the immune system in RA, manipulation of which may offer the potential for even safer and more effective treatments in the future.

Isovitexin Inhibits Ginkgolic Acids-Induced Inflammation Through Downregulating SHP2 Activation

It has been reported that Celtis sinensis Pers. is employed as a folk medicine for the treatment of inflammatory diseases. But the mechanism supporting its use as anti-inflammatory remains unclear. To investigate the anti-inflammatory of Celtis sinensis Pers. ICR mice were provided Celtis sinensis Pers. leaf extract (CLE) at 100, 200 mg/kg after ginkgolic acids (GA) sensitization. Our data showed that CLE and the main flavonoid isovitexin in CLE could ameliorate GA-induced contact dermatitis in mice. Ear swelling, inflammatory cell infiltration and splenomegaly were inhibited significantly by isovitexin, while the weight loss of mice in the isovitexin-treated group was much better than that in the dexamethasone-treated group (positive control drug). It has been reported in previous research that GA-induced inflammation is closely related to the T cell response. Therefore, T cells were the focus of the anti-inflammatory effect of isovitexin in this paper. The in vivo results showed that isovitexin (10, 20 mg/kg) inhibited the expression of proinflammatory cytokines (TNF-α, IFN-γ, IL-2 and IL-17A) in lymph nodes, inhibited the secretion of cytokines into the serum from mice with contact dermatitis and promoted the expression of apoptosis-related proteins. In vitro, isovitexin also induced apoptosis and inhibited proinflammatory cytokine expression in Con A-activated T cells. Further study showed that the MAPK and STAT signaling pathways and the phosphorylation of SHP2 were inhibited by isovitexin. Both molecular docking and biological experiments indicated that SHP2 may be an anti-inflammatory target of isovitexin in T cells. Taken together, isovitexin can serve as a potential natural agent for the treatment or prevention of GA-induced inflammatory problems.

Rheumatoid arthritis: Development after the emergence of a chemokine for neutrophils in the synovium

Rheumatoid arthritis (RA) may not be a multifactorial disease; it can be hypothesized that RA is developed through a series of events following a triggering event, which is the emergence of a chemokine for neutrophils in the synovium. IL-17A, secreted by infiltrated neutrophils, stimulates synoviocytes to produce CCL20, which attracts various CCR6-expressing cells, including Th17 cells. Monocytes (macrophages) appear after neutrophil infiltration according to the natural course of inflammation and secrete IL-1β and TNFα. Then, IL-17A, IL-1β, and TNFα stimulate synoviocytes to produce CCL20, amplifying the inflammation. Varieties of chemokines secreted by infiltrating cells accumulate in the synovium and induce synoviocyte proliferation by binding to the corresponding G protein-coupled receptors, thus expanding the synovial tissue. CCL20 in this tissue attracts circulating monocytes that express both CCR6 and receptor activator of NF-κB (RANK), which differentiate into osteoclasts in the presence of RANKL. In this way, pannus is formed, and bone destruction begins.

Promising Therapeutic Targets for Treatment of Rheumatoid Arthritis

Rheumatoid arthritis (RA) is a systemic poly-articular chronic autoimmune joint disease that mainly damages the hands and feet, which affects 0.5% to 1.0% of the population worldwide. With the sustained development of disease-modifying antirheumatic drugs (DMARDs), significant success has been achieved for preventing and relieving disease activity in RA patients. Unfortunately, some patients still show limited response to DMARDs, which puts forward new requirements for special targets and novel therapies. Understanding the pathogenetic roles of the various molecules in RA could facilitate discovery of potential therapeutic targets and approaches. In this review, both existing and emerging targets, including the proteins, small molecular metabolites, and epigenetic regulators related to RA, are discussed, with a focus on the mechanisms that result in inflammation and the development of new drugs for blocking the various modulators in RA.

The modulatory effect and implication of gut microbiota on osteoporosis: from the perspective of "brain-gut-bone" axis

Osteoporosis (OP) is a kind of systemic metabolic disease characterized by decreased bone mass and destruction of the bone microstructure. In recent years, it has become an expected research trend to explore the cross-linking relationship in the pathogenesis process of OP so as to develop reasonable and effective intervention strategies. With the further development of intestinal microbiology and the profound exploration of the gut microbiota (GM), it has been further revealed that the "brain-gut" axis may be a potential target for the bone, thereby affecting the occurrence and progression of OP. Hence, based on the concept of "brain-gut-bone" axis, we look forward to deeply discussing and summarizing the cross-linking relationship of OP in the next three parts, including the "brain-bone" connection, "gut-bone" connection, and "brain-gut" connection, so as to provide an emerging thought for the prevention strategies and mechanism researches of OP.

CCN proteins in the musculoskeletal system: current understanding and challenges in physiology and pathology

The acronym for the CCN family was recently revised to represent “cellular communication network”. These six, small, cysteine-enriched and evolutionarily conserved proteins are secreted matricellular proteins, that convey and modulate intercellular communication by interacting with structural proteins, signalling factors and cell surface receptors. Their role in the development and physiology of musculoskeletal system, constituted by connective tissues where cells are interspersed in the cellular matrix, has been broadly studied. Previous research has highlighted a crucial balance of CCN proteins in mesenchymal stem cell commitment and a pivotal role for CCN1, CCN2 and their alter ego CCN3 in chondrogenesis and osteogenesis; CCN4 plays a minor role and the role of CCN5 and CCN6 is still unclear. CCN proteins also participate in osteoclastogenesis and myogenesis. In adult life, CCN proteins serve as mechanosensory proteins in the musculoskeletal system providing a steady response to environmental stimuli and participating in fracture healing. Substantial evidence also supports the involvement of CCN proteins in inflammatory pathologies, such as osteoarthritis and rheumatoid arthritis, as well as in cancers affecting the musculoskeletal system and bone metastasis. These matricellular proteins indeed show involvement in inflammation and cancer, thus representing intriguing therapeutic targets. This review discusses the current understanding of CCN proteins in the musculoskeletal system as well as the controversies and challenges associated with their multiple and complex roles, and it aims to link the dispersed knowledge in an effort to stimulate and guide readers to an area that the writers consider to have significant impact and relevant potentialities.

Evaluation of serum interleukin-6 (IL-6), IL-13, and IL-17 levels and computed tomography finding in interstitial lung disease associated with connective tissue disease patients

OBJECTIVE

Interstitial lung disease (ILD) is one of the most severe complications which is associated with connective tissue disease (CTD) and causes to morbidity and mortality. So, we aimed to determine serum levels of interleukin-6 (IL-6), IL-13, and IL-17, to investigate whether these cytokines are related to CTD-ILD, and to find their possible contribution to determining the prognosis of the disease.

METHODS

A total of 150 participants, 80 patients diagnosed with CTD-ILD (mean age, 58.21 ± 12.36) and 70 healthy controls (mean age, 57.07 ± 9.60) were recruited from the rheumatology department between January 2016 and June 2019 in the study. High-resolution computed tomography (HRCT) findings were scored as similarly to previous studies. Serum IL-6, IL 13, and IL-17 levels were measured by ELISA test kits.

RESULTS

The levels of IL-6, IL-13, and IL-17 in CTD patients were significantly higher than the healthy individuals (p < 001), but the HRCT score's relation were not determined. IL-6 was associated with disease duration and disease activity scores of DAS28, ESDAII, and dSSc. There was a significant relation between dSSc, HCRT fibrosis, and total score.CRP, hemoglobin, and platelets were associated with the HRCT inflammation pattern.

CONCLUSION

At the study, it has been observed that serum IL-13, IL-6 and IL-17 levels are increased in patients with CTD-ILD. Besides, IL-6 was associated with disease activity scores of DAS28, ESDAII, and dSSc. Also, HRCT fibrosis score is associated with dSSc. Further and comprehensive studies are needed to understand better the complex intersection of lung disease with systemic autoimmunity. Key Points • Serum IL-13, IL-6, and IL-17 levels are increased in patients with CTD-ILD. • IL-6 was associated with disease activity scores of DAS28, ESDAII, and diffuse skin involvement. • HRCT fibrosis score is associated with diffuse skin involvement in patients with SSc-ILD. • HRCT inflammation score is associated with PAH.

Bone loss in patients with inflammatory bowel disease: cause, detection and treatment

PURPOSE OF REVIEW

Inflammatory bowel disease (IBD) is associated with bone loss leading to osteoporosis and increased fracture risk. Bone loss is the result of changes in the balanced process of bone remodeling. Immune cells and cytokines play an important role in the process of bone remodeling and it is therefore not surprising that cytokines as observed in IBD are involved in bone pathology. This review discusses the role of cytokines in IBD-associated bone loss, including the consequences for treatment.

RECENT FINDINGS

Many studies have been conducted that showed the effect of a single cytokine on bone cells in vitro, including interleukin (IL)-1β, IL-6, IL-8, IL-12/IL-23, IL-17, IL-18, IL-32 and interferon-γ. Recently new members of the IL-1 family (IL-1F) have been related to IBD but the consequences for bone health remain uncertain.

SUMMARY

Overall, patients have to deal with a cocktail of cytokines, present in their serum. The combination of cytokines can affect bone cells differently compared to the effects of a single cytokine. This implicates that treatment, focused on reducing the inflammation could work best for bone health as well. Vitamin D might also play a role in this.

Effect of interleukin-6, -17, -21, -22, and -23 and STAT3 on signal transduction pathways and their inhibition in autoimmune arthritis

Rheumatic diseases are complex autoimmune diseases which include among others rheumatoid arthritis (RA), juvenile idiopathic arthritis (JIA), and psoriatic arthritis (PsA). These diseases are characterized by prolonged and increased secretion of inflammatory factors, eventually leading to inflammation. This is often accompanied by persistent pain and stiffness in the joint and finally bone destruction and osteoporosis. These diseases can occur at any age, regardless of gender or origin. Autoimmune arthritis is admittedly associated with long-term treatment, and discontinuation of medication is associated with unavoidable relapse. Therefore, it is important to detect the disease at an early stage and apply appropriate preventative measures. During inflammation, pro-inflammatory factors such as interleukins (IL)-6, -17, -21, -22, and -23 are secreted, while anti-inflammatory factors including IL-10 are downregulated. Research conducted over the past several years has focused on inhibiting inflammatory pathways and activating anti-inflammatory factors to improve the quality of life of people with rheumatic diseases. The aim of this paper is to review current knowledge on stimulatory and inhibitory pathways involving the signal transducer and activator of transcription 3 (STAT3). STAT3 has been shown to be one of the crucial factors involved in inflammation and is directly linked with other pro-inflammatory factors and thus is a target of current research on rheumatoid diseases.

IL-17A is involved in diabetic inflammatory pathogenesis by its receptor IL-17RA

IMPACT STATEMENT

The participation of interleukin (IL)-17A in diabetic pathogenesis is suggested in animal models of autoimmune diabetes and in patients with type 1 diabetes (T1D), but with some contradictory results. Particularly, evidence for a direct injury of IL-17A to pancreatic β cells is lacking. We showed that IL-17A deficiency alleviated diabetic signs including hyperglycemia, hypoinsulinemia, and inflammatory response in Ins2Akita (Akita) mice, a T1D model with spontaneous mutation in insulin 2 gene leading to β-cell apoptosis. IL-17A enhanced inflammatory reaction, oxidative stress, and cell apoptosis but attenuated insulin level in mouse insulin-producing MIN6 cells. IL-17A had also a synergistic destruction to MIN6 cells with streptozotocin (STZ), a pancreatic β-cell-specific cytotoxin. Blocking IL-17 receptor A (IL-17RA) reduced all these deleterious effects of IL-17A on MIN6 cells. The results demonstrate the role and the importance of IL-17A in T1D pathogenesis and suggest a potential therapeutic strategy for T1D targeting IL-17A and/or IL-17RA.

Cyr61 synthesis is induced by interleukin-6 and promotes migration and invasion of fibroblast-like synoviocytes in rheumatoid arthritis

Background

Interleukin-6 (IL-6) is involved in fibroblast-like synoviocyte (FLS) activation and promotes pannus formation and bone and cartilage destruction in rheumatoid arthritis (RA). Cysteine-rich 61 (Cyr61) protein regulates cell proliferation, migration, and differentiation. The aim of this study was to investigate the role of Cyr61 in RA-FLS migration and invasion after IL-6 stimulation.

Methods

Western blotting, immunohistochemistry, reverse transcription-polymerase chain reaction, and real time-polymerase chain reaction were used to examine protein and mRNA levels of Cyr61, matrix metalloproteinases (MMPs), and other signalling proteins. Knockdown of gene expression was performed with siRNA, and RNA sequencing was performed for differential gene analysis. Migration and invasion were assessed by wound healing and Boyden chamber assays.

Results

Cyr61 levels were elevated in FLSs from RA patients compared to those in osteoarthritis patients. Control and IL-6-treated FLSs showed differential gene expression. IL-6 stimulated protein synthesis of Cyr61, which was attenuated by the extracellular signal-related kinase 1/2 (ERK 1/2) inhibitor, PD98059, and knockdown of early growth response 3 (EGR3), but not of JUN. IL-6-induced Cyr61 protein synthesis increased expression of MMP2. Cyr61 promoted FLS migration and invasion in an autocrine manner. Knockdown of CYR61 and a neutralising antibody attenuated Cyr61 synthesis and IL-6-induced FLS migration.

Conclusions

By modulating the ERK/EGR3 pathway, IL-6 stimulated Cyr61 production and in turn increased invasiveness of FLS. Our data suggest that Cyr61 might be a potential target to prevent the progression of joint damage in RA.

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.

The pathogenic importance of CCL21 and CCR7 in rheumatoid arthritis

Innate and adaptive immunity regulate the inflammatory and erosive phenotypes observed in rheumatoid arthritis (RA) patients. Hence, identifying novel pathways that participate in different stages of RA pathology will provide valuable insights concerning the mechanistic behavior of different joint leukocytes and the strategy to restrain their activity. Recent findings have revealed that CCL21 poses as a risk factor for RA and expression of its receptor, CCR7, on circulating monocytes is representative of the patient's disease activity score. Expression of CCR7 was found to be the hallmark of RA synovial fluid (SF) M1 macrophages (MФs) and its levels were potentiated in response to M1 mediating factors and curtailed by M2 mediators in naïve MФs. Intriguingly, although both CCR7 ligands, CCL19 and CCL21, are elevated in RA specimens, only CCL21 was predominately responsible for CCR7's pathological manifestation of RA. Unique subset of MФs differentiated in response to CCL21 stimulation, exhibited upregulation in Th17-polarizing monokines. Moreover, CCL21-activated monokines were capable of differentiating naïve T cells into joint Th17 cells, which also partook in RA osteoclastogenesis. Finally, to conserve chronic inflammation, SF CCL21 amplified RA neovascularization directly and indirectly by promoting RA FLS and MΦs to secrete proangiogenic factors, VEGF and IL-17. This review aims to shed light on the broad pathogenic impact of CCL21, linking immunostimulatory MФs with Th17 cells, while concurrently advancing RA bone destruction and neovascularization.

Innate Lymphocytes in Inflammatory Arthritis

Inflammatory arthritis (IA) refers to a group of chronic diseases, including rheumatoid arthritis (RA), psoriatic arthritis (PsA), ankylosing spondylitis (AS), and other spondyloarthritis (SpA). IA is characterized by autoimmune-mediated joint inflammation and is associated with inflammatory cytokine networks. Innate lymphocytes, including innate-like lymphocytes (ILLs) expressing T or B cell receptors and innate lymphoid cells (ILCs), play important roles in the initiation of host immune responses against self-antigens and rapidly produce large amounts of cytokines upon stimulation. TNF (Tumor Necrosis Factor)-α, IFN (Interferon)-γ, Th2-related cytokines (IL-4, IL-9, IL-10, and IL-13), IL-17A, IL-22, and GM-CSF are involved in IA and are secreted by ILLs and ILCs. In this review, we focus on the current knowledge of ILL and ILC phenotypes, cytokine production and functions in IA. A better understanding of the roles of ILLs and ILCs in IA initiation and development will ultimately provide insights into developing effective strategies for the clinical treatment of IA patients.

Network Pharmacology to Identify the Pharmacological Mechanisms of a Traditional Chinese Medicine Derived from Trachelospermum jasminoides in Patients with Rheumatoid Arthritis

BACKGROUND This study used a network pharmacology approach to identify the pharmacological mechanisms of a traditional Chinese medicine derived from Trachelospermum jasminoides (Lindl.) Lem. in patients with rheumatoid arthritis (RA). MATERIAL AND METHODS Known compounds of T. jasminoides were obtained from the Traditional Chinese Medicine Systems Pharmacology (TCMSP) database, the Shanghai Institute of Organic Chemistry of Chinese Academy of Science, Chemistry (CASC) database, and a literature search. Putative targets of identified compounds were predicted by SwissTargetPrediction. RA-related targets were achieved from the Therapeutic Target database, Drugbank database, Pharmacogenomics Knowledgebase, and Online Mendelian Inheritance in Man database. The protein-protein interaction (PPI) network was built by STRING. CluGO was utilized for Kyoto Encyclopedia of Genes and Genomes (KEGG) and Gene Ontology (GO) enrichment analysis. RESULTS A total of 354 potential targets were predicted for the 17 bioactive compounds in T. jasminoides; 69 of these targets overlapped with RA-related targets. A PPI network was composed and 2 clusters of 59 and 42 nodes each were excavated. GO and KEGG enrichment analysis of the overlapping targets and the 2 clusters was mainly grouped into immunity, inflammation, estrogen, anxiety, and depression processes. CONCLUSIONS Our study illustrated that T. jasminoides alleviates RA through the interleukin-17 signaling pathway, the tumor necrosis factor signaling pathway, and other immune and inflammatory-related processes. It also may exert effects in regulating cell differentiation and potentially has anti-anxiety, anti-depression, and estrogen-like effects.

Osteocyte-Related Cytokines Regulate Osteoclast Formation and Bone Resorption

The process of bone remodeling is the result of the regulated balance between bone cell populations, namely bone-forming osteoblasts, bone-resorbing osteoclasts, and the osteocyte, the mechanosensory cell type. Osteoclasts derived from the hematopoietic stem cell lineage are the principal cells involved in bone resorption. In osteolytic diseases such as rheumatoid arthritis, periodontitis, and osteoporosis, the balance is lost and changes in favor of bone resorption. Therefore, it is vital to elucidate the mechanisms of osteoclast formation and bone resorption. It has been reported that osteocytes express Receptor activator of nuclear factor κΒ ligand (RANKL), an essential factor for osteoclast formation. RANKL secreted by osteocytes is the most important factor for physiologically supported osteoclast formation in the developing skeleton and in pathological bone resorption such as experimental periodontal bone loss. TNF-α directly enhances RANKL expression in osteocytes and promotes osteoclast formation. Moreover, TNF-α enhances sclerostin expression in osteocytes, which also increases osteoclast formation. These findings suggest that osteocyte-related cytokines act directly to enhance osteoclast formation and bone resorption. In this review, we outline the most recent knowledge concerning bone resorption-related cytokines and discuss the osteocyte as the master regulator of bone resorption and effector in osteoclast formation.

Study of anti-inflammatory activity of Fatsiphloginum™ (Fatsia japonica) and a new purified triterpene-rich extract of saponins (PS-551) in experimental model of arthritis

In this study, two extracts from Fatsia japonica-Fatsiphloginum™ (extract of triterpene glycosides containing 45-50 % of fatsiosides (FS)) and purified triterpene-rich extract of saponins with code name PS-551 (PS) were administered in combination with methotrexate (MTX) and in monotherapy to rats suffering adjuvant arthritis (AA). The anti-inflammatory activities of extracts were evaluated as monotherapies in comparison with untreated AA. PS administered in higher dose showed on day 28 effective decrease of hind paw volume (HPV), decreased activity of gamma-glutamyl transferase (GGT) in joints, and also interleukin-17A was decreased significantly on day 14. The higher dose of PS was more effective than both doses of FS. Further, we evaluated the higher doses of PS and FS in combination with MTX. PS improved the effect of MTX in combination more effective than FS (HPV, body weight and activity of GGT in joint). However, FS was more effective in reducing the level of IL-17A on day 14 and activity of GGT in spleen than PS. In conclusion, our study showed that generally FS has higher anti-arthritic activity comparing to PS. Thus, the novel combination of Fatsiphloginum™ and methotrexate could be interesting for future clinical studies in patients suffering auto-immune diseases.

Perspective on skeletal health in inflammatory bowel disease

Osteopenia and osteoporosis are common features in inflammatory bowel disease (IBD), comprising both Crohn's disease and ulcerative colitis. Moreover, Crohn's disease is associated with increased fracture risk. The etiology of bone loss in IBD is multifactorial. It includes insufficient intake or absorption of calcium, vitamin D, and potassium; smoking; a low peak bone mass; a low body mass index; and decreased physical activity. In several studies, it has been shown that elevated concentrations of systemic and local pro-inflammatory cytokines, including tumor necrosis factor alpha (TNF-α), interferon-γ (IFNγ), interleukin (IL)-1β, IL-4, IL-5, IL-6, IL-13, and IL-17, present in IBD patients are potentially detrimental for bone metabolism and may be responsible for bone loss and increased fracture risk. This perspective aims to review the current literature on the role of inflammatory factors in the pathophysiology of skeletal problems in IBD and to suggest potential treatment to improve bone health, based on a combination of evidence and clinical and pathophysiological reasoning.

A C-terminal peptide from type I interferon protects the retina in a mouse model of autoimmune uveitis

Experimental autoimmune uveitis (EAU) in rodents recapitulates many features of the disease in humans and has served as a useful tool for the development of therapeutics. A peptide from C-terminus of interferon α1, conjugated to palmitoyl-lysine for cell penetration, denoted as IFNα-C, was tested for its anti-inflammatory properties in ARPE-19 cells, followed by testing in a mouse model of EAU. Treatment with IFNα-C and evaluation by RT-qPCR showed the induction of anti-inflammatory cytokines and chemokine. Inflammatory markers induced by treatment with TNFα were suppressed when IFNα-C was simultaneously present. TNF-α mediated induction of NF-κB and signaling by IL-17A were attenuated by IFNα-C. Differentiated ARPE-19 cells were treated with TNFα in the presence or absence IFNα-C and analyzed by immmunhistochemistry. IFNα-C protected against the disruption integrity of tight junction proteins. Similarly, loss of transepithelial resistance caused by TNFα was prevented by IFNα-C. B10.RIII mice were immunized with a peptide from interphotoreceptor binding protein (IRBP) and treated by gavage with IFNα-C. Development of uveitis was monitored by histology, fundoscopy, SD-OCT, and ERG. Treatment with IFNα-C prevented uveitis in mice immunized with the IRBP peptide. Splenocytes isolated from mice with ongoing EAU exhibited antigen-specific T cell proliferation that was inhibited in the presence of IFNα-C. IFNα-C peptide exhibits anti-inflammatory properties and protects mice against damage to retinal structure and function suggesting that it has therapeutic potential for the treatment of autoimmune uveitis.

Cyanidin prevents the hyperproliferative potential of fibroblast-like synoviocytes and disease progression via targeting IL-17A cytokine signalling in rheumatoid arthritis

The hyperplastic phenotype of fibroblast-like synoviocytes (FLSs) plays an important role for synovitis, chronic inflammation and joint destruction in rheumatoid arthritis (RA). Interleukin 17A (IL-17A), a signature pro-inflammatory cytokine effectively influences the hyperplastic transformation of FLS cells and synovial pannus growth. IL-17A cytokine signalling participates in RA pathology by regulating an array of pro-inflammatory mediators and osteoclastogenesis. Cyanidin, a key flavonoid inhibits IL-17A/IL-17 receptor A (IL-17RA) interaction and alleviates progression and disease severity of psoriasis and asthma. However, the therapeutic efficacy of cyanidin on IL-17A cytokine signalling in RA remains unknown. In the present study, cyanidin inhibited IL-17A induced migratory and proliferative capacity of FLS cells derived from adjuvant-induced arthritis (AA) rats. Cyanidin treatment reduced IL-17A mediated reprogramming of AA-FLS cells to overexpress IL-17RA. In addition, significantly decreased expression of IL-17A dependent cyr61, IL-23, GM-CSF, and TLR3 were observed in AA-FLS cells in response to cyanidin. At the molecular level, cyanidin modulated IL-17/IL-17RA dependent JAK/STAT-3 signalling in AA-FLS cells. Importantly, cyanidin activated PIAS3 protein to suppress STAT-3 specific transcriptional activation in AA-FLS cells. Cyanidin treatment to AA rats attenuated clinical symptoms, synovial pannus growth, immune cell infiltration, and bone erosion. Cyanidin reduced serum level of IL-23 and GM-CSF and expression of Cyr 61 and TLR3 in the synovial tissue of AA rats. Notably, the level of p-STAT-3 protein was significantly decreased in the synovial tissue of AA rats treated with cyanidin. This study provides the first evidence that cyanidin can be used as IL-17/17RA signalling targeting therapeutic drug for the treatment of RA and this need to be investigated in RA patients.

Evaluation of the effect of GM-CSF blocking on the phenotype and function of human monocytes

Granulocyte-macrophage colony-stimulating factor (GM-CSF) is a multipotent cytokine that prompts the proliferation of bone marrow-derived macrophages and granulocytes. In addition to its effects as a growth factor, GM-CSF plays an important role in chronic inflammatory autoimmune diseases such as multiple sclerosis and rheumatoid arthritis. Reports have identified monocytes as the primary target of GM-CSF; however, its effect on monocyte activation has been under-estimated. Here, using flow cytometry and ELISA we show that GM-CSF induces an inflammatory profile in human monocytes, which includes an upregulated expression of HLA-DR and CD86 molecules and increased production of TNF-α and IL-1β. Conversely, blockage of endogenous GM-CSF with antibody treatment not only inhibited the inflammatory profile of these cells, but also induced an immunomodulatory one, as shown by increased IL-10 production by monocytes. Further analysis with qPCR, flow cytometry and ELISA experiments revealed that GM-CSF blockage in monocytes stimulated production of the chemokine CXCL-11, which suppressed T cell proliferation. Blockade of CXCL-11 abrogated anti-GM-CSF treatment and induced inflammatory monocytes. Our findings show that anti-GM-CSF treatment induces modulatory monocytes that act in a CXCL-11-dependent manner, a mechanism that can be used in the development of novel approaches to treat chronic inflammatory autoimmune diseases.

The role of JAK/STAT signaling pathway and its inhibitors in diseases

The JAK/STAT signaling pathway is an universally expressed intracellular signal transduction pathway and involved in many crucial biological processes, including cell proliferation, differentiation, apoptosis, and immune regulation. It provides a direct mechanism for extracellular factors-regulated gene expression. Current researches on this pathway have been focusing on the inflammatory and neoplastic diseases and related drug. The mechanism of JAK/STAT signaling is relatively simple. However, the biological consequences of the pathway are complicated due to its crosstalk with other signaling pathways. In addition, there is increasing evidence indicates that the persistent activation of JAK/STAT signaling pathway is closely related to many immune and inflammatory diseases, yet the specific mechanism remains unclear. Therefore, it is necessary to study the detailed mechanisms of JAK/STAT signaling in disease formation to provide critical reference for clinical treatments of the diseases. In this review, we focus on the structure of JAKs and STATs, the JAK/STAT signaling pathway and its negative regulators, the associated diseases, and the JAK inhibitors for the clinical therapy.

Glutamine Metabolism Is Essential for Stemness of Bone Marrow Mesenchymal Stem Cells and Bone Homeostasis

Skeleton has emerged as an endocrine organ which is both capable of regulating energy metabolism and being a target for it. Glutamine is the most bountiful and flexible amino acid in the body which provides adenosine 5′-triphosphate (ATP) demands for cells. Emerging evidences support that glutamine which acts as the second metabolic regulator after glucose exerts crucial roles in bone homeostasis at cellular level, including the lineage allocation and proliferation of bone mesenchymal stem cells (BMSCs), the matrix mineralization of osteoblasts, and the biosynthesis in chondrocytes. The integrated mechanism consisting of WNT, mammalian target of rapamycin (mTOR), and reactive oxygen species (ROS) signaling pathway in a glutamine-dependent pattern is responsible to regulate the complex intrinsic biological process, despite more extensive molecules are deserved to be elucidated in glutamine metabolism further. Indeed, dysfunctional glutamine metabolism enhances the development of degenerative bone diseases, such as osteoporosis and osteoarthritis, and glutamine or glutamine progenitor supplementation can partially restore bone defects which may promote treatment of bone diseases, although the mechanisms are not quite clear. In this review, we will summarize and update the latest research findings and clinical trials on the crucial regulatory roles of glutamine metabolism in BMSCs and BMSC-derived bone cells, also followed with the osteoclasts which are important in bone resorption.

Roles of GM-CSF in the Pathogenesis of Autoimmune Diseases: An Update

Granulocyte-macrophage colony-stimulating factor (GM-CSF) was first described as a growth factor that induces the differentiation and proliferation of myeloid progenitors in the bone marrow. GM-CSF also has an important cytokine effect in chronic inflammatory diseases by stimulating the activation and migration of myeloid cells to inflammation sites, promoting survival of target cells and stimulating the renewal of effector granulocytes and macrophages. Because of these pro-cellular effects, an imbalance in GM-CSF production/signaling may lead to harmful inflammatory conditions. In this context, GM-CSF has a pathogenic role in autoimmune diseases that are dependent on cellular immune responses such as multiple sclerosis (MS) and rheumatoid arthritis (RA). Conversely, a protective role has also been described in other autoimmune diseases where humoral responses are detrimental such as myasthenia gravis (MG), Hashimoto's thyroiditis (HT), inflammatory bowel disease (IBD), and systemic lupus erythematosus (SLE). In this review, we aimed for a comprehensive analysis of literature data on the multiple roles of GM-CSF in autoimmue diseases and possible therapeutic strategies that target GM-CSF production.

A Network Pharmacology Study on the Active Ingredients and Potential Targets of Tripterygium wilfordii Hook for Treatment of Rheumatoid Arthritis

Traditional Chinese medicine has specific effect on some chronic diseases in clinic, especially in rheumatic diseases. Tripterygium wilfordii Hook (TWH) is a traditional Chinese medicine commonly used in the treatment of rheumatoid arthritis (RA); the unique therapeutic effect has been confirmed by a large number of research papers. TWH has many compounds that lead to its active compounds. However, the potential targets and pharmacological and molecular mechanism of its action treatment of rheumatic diseases are not entirely clear. Therefore, the network pharmacology approach is needed to further study and explore its treatment mechanism. We have successfully set up 10 networks, including four major networks and other networks. Four major networks include rheumatoid arthritis disease network, compound-compound target network of TWH, TWH compound target-rheumatoid arthritis disease network, and TWH-rheumatoid arthritis disease-mechanism network. Other networks consist of RA disease and TWH related targets clusters, biological processes, and pathways network. Our study successfully predicted, explained, and confirmed the TWH of RA disease molecular synergy and found the potential of RA related targets, cluster, biological process, and pathways. This study not only provides prompts to the researcher who explores pharmacological and biological molecular mechanism of TWH applying to RA disease, but also proves a feasible method for discovering potential activated compounds from Chinese herbs.

T-cells interact with B cells, dendritic cells, and fibroblast-like synoviocytes as hub-like key cells in rheumatoid arthritis

Rheumatoid arthritis (RA) is a chronic inflammatory synovitis-based systemic disease characterized by invasive joint inflammation and synovial hyperplasia, which can lead to arthrentasis and defunctionalization. Previous research has shown that T cells, B cells, dendritic cells (DCs), and fibroblast-like synoviocytes (FLSs) play vital roles in the regulation of RA. Both T follicular helper (Tfh) cells and helper T (Th) 17 cells play immunomodulatory roles in RA. Moreover, interleukin-23 (IL-23), and IL-17 are vital to the pathogenesis of RA. T cells behave as a hub, in that B cells, DCs, and FLSs can interact with T cells to inhibit their activation and interfere with the process of RA. T cells cooperate with B cells, DCs, and FLSs to maintain the stability of the immune system under physiological conditions. However, under pathological conditions, the balance is disrupted, and the interaction of T cells with other cells may intensify disease progression. This review focuses on the interaction of T cells with B cells, DCs, and FLSs in different tissues and organs of RA patients and animal models, and highlight that the interplay between immune cells may underline the unique function of T cells and the application prospect of targeting T cell treatment for RA.

Ferulic acid inhibits interleukin 17-dependent expression of nodal pathogenic mediators in fibroblast-like synoviocytes of rheumatoid arthritis

Interleukin 17 (IL-17), a proinflammatory cytokine produced by T helper (Th) 17 cells, potentially controls fibroblast-like synoviocytes (FLS)-mediated disease activity of rheumatoid arthritis (RA) via IL-17/ IL-17 receptor type A (IL-17RA)/signal transducer and activator of transcription 3 (STAT-3) signaling cascade. This has suggested that targeting IL-17 signaling could serve as an important strategy to treat FLS-mediated RA progression. Ferulic acid (FA), a key polyphenol, attenuates the development of gouty arthritis and cancer through its anti-inflammatory effects, but its therapeutic efficiency on IL-17 signaling in FLS-mediated RA pathogenesis remains unknown. In the current study, FA markedly inhibited the IL-17-mediated expression of its specific transmembrane receptor IL-17RA in FLS isolated from adjuvant-induced arthritis (AA) rats. Importantly, FA dramatically suppressed the IL-17-mediated expression of toll-like receptor 3 (TLR-3), cysteine-rich angiogenic inducer 61 (Cyr61), IL-23, granulocyte-macrophage colony stimulating factor (GM-CSF) in AA-FLS via the inhibition of IL-17/IL-17RA/STAT-3 signaling cascade. In addition, FA significantly decreased the formation of osteoclast cells and bone resorption potential in a coculture system consisting of IL-17 treated AA-FLS and rat bone marrow derived monocytes/macrophages. Furthermore, FA remarkably inhibited the IL-17-mediated expression of receptor activator of nuclear factor κ-Β ligand (RANKL) and increased the expression of osteoprotegerin (OPG) in AA-FLS via the regulation of IL-17/IL-17RA/STAT-3 signaling cascade. The therapeutic efficiency of FA on IL-17 signaling was further confirmed by knockdown of IL-17RA using small interfering RNA or blocking of STAT-3 activation with S3I-201. The molecular docking analysis revealed that FA manifests significant ligand efficiency toward IL-17RA, STAT-3, IL-23, and RANKL proteins. This study provides new evidence that FA can be used as a potential therapeutic agent for inhibiting IL-17-mediated disease severity and bone erosion in RA.

Repetitive Exposure of IL-17 Into the Murine Air Pouch Favors the Recruitment of Inflammatory Monocytes and the Release of IL-16 and TREM-1 in the Inflammatory Fluids

The infiltration of Th17 cells in tissues and organs during the development of many autoimmune diseases is considered a key step toward the establishment of chronic inflammation. Indeed, the localized and prolonged release of IL-17 in specific tissues has been associated with an increased severity of the inflammatory response that remains sustained over time. The cellular and molecular mechanisms behind these effects are far from being clear. In this study we investigated the effects of two repetitive administration of recombinant IL-17 into the murine air pouch to simulate a scenario where IL-17 is released over time in a pre-inflamed tissue. Consistent with our previous observations, mice receiving a single dose of IL-17 showed a transitory influx of neutrophils into the air pouch that peaked at 24 h and declined at 48 h. Conversely, mice receiving a double dose of the cytokine—one at time 0 and the second after 24 h—showed a more dramatic inflammatory response with almost 2-fold increase in the number of infiltrated leukocytes and significant higher levels of TNF-α and IL-6 in the inflammatory fluids. Further analysis of the exacerbated inflammatory response of double-injected IL-17 mice showed a unique cellular and biochemical profile with inflammatory monocytes as the second main population emigrating to the pouch and IL-16 and TREM-1 as the most upregulated cytokines found in the inflammatory fluids. Most interestingly, mice receiving a double injection of IL-1β did not show any change in the cellular or biochemical inflammatory response compared to those receiving a single injection or just vehicle. Collectively these results shed some light on the function of IL-17 as pro-inflammatory cytokine and provide possible novel ways to target therapeutically the pathogenic effects of IL-17 in autoimmune conditions.

A microfluidic chip-based co-culture of fibroblast-like synoviocytes with osteoblasts and osteoclasts to test bone erosion and drug evaluation

Targeting fibroblast-like synoviocyte (FLS) migration and invasion-mediated bone erosion is a promising clinical strategy for the treatment of rheumatoid arthritis (RA). Drug sensitivity testing is fundamental to this scheme. We designed a microfluidic chip-based, cell co-cultured platform to mimic RA FLS-mediated bone erosion and perform drug-sensitive assay. Human synovium SW982 cells were cultured in the central channel and migrated to flow through matrigel-coated side channels towards cell culture chamber where RANKL-stimulated osteoclastic RAW264.7 and osteogenic medium (OS)-stimulated bone marrow mesenchymal stem cells (BMSC) were cultured in the microfluidic chip device, mimicking FLS migration and invasion-mediated bone erosion in RA. These SW982 cells showed different migration potentials to osteoclasts and BMSC. The migration of SW982 cells with high expression of cadherin-11 was more potent when SW982 cells were connected with the co-culture of RAW264.7 and BMSC. Simultaneously, in the co-cultured chamber, tartrate-resistant acid phosphatase (TRAP) activity of RANKL-stimulated RAW264.7 cells was enhanced, but alkaline phosphatase (ALP) activity was decreased in comparison with mono-cultured chamber. Furthermore, it was confirmed that celastrol, a positive drug for the treatment of RA, inhibited SW982 cell migration as well as TRAP activity in the cell-cultured microfluidic chips. Thus, the migration and invasion to bone-related cells was reconstituted on the microfluidic model. It may provide an effective anti-RA drug screen model for targeting FLS migration-mediated bone erosion.

Ferulaldehyde Improves the Effect of Methotrexate in Experimental Arthritis

Methotrexate (MTX) is still the gold standard for treatment of rheumatoid arthritis (RA). The therapeutic efficacy of low-dose of MTX can be increased by its combination with a natural substance, ferulaldehyde (FRA). The aim of this study was to evaluate the effect FRA and MTX administered alone or in combination in adjuvant arthritis. The disease was induced to Lewis male rats by intradermal injection, which contains a suspension of heat-inactivated Mycobacterium butyricum in incomplete Freund’s adjuvant. The experiment of 28 days included: healthy animals, arthritic animals, arthritic animals with administration of FRA at the oral daily dose of 15 mg/kg, arthritic animals with administration of MTX at the oral dose of 0.3 mg/kg twice a week, and arthritic animals administered with FRA and MTX. FRA in monotherapy decreased significantly only the level of interleukin-1β (IL-1β) and matrix metalloproteinase-9 in plasma. Combination of FRA and low-dose MTX was more effective than MTX alone when comparing body weight, hind paw volume, arthritic score, plasmatic levels of IL-1β, activity of γ-glutamyl transferase, and relative mRNA expression of IL-1β in the spleen. Therefore, the combination treatment was the most effective. The obtained results are interesting for future possible innovative therapy of patients with RA.