MX2: Identification and systematic mechanistic analysis of a novel immune-related biomarker for systemic lupus erythematosus.

Background: Systemic lupus erythematosus (SLE) is an autoimmune disease that involves multiple organs. However, the current SLE-related biomarkers still lack sufficient sensitivity, specificity and predictive power for clinical application. Thus, it is significant to explore new immune-related biomarkers for SLE diagnosis and development. Methods: We obtained seven SLE gene expression profile microarrays (GSE121239/11907/81622/65391/100163/45291/49454) from the GEO database. First, differentially expressed genes (DEGs) were screened using GEO2R, and SLE biomarkers were screened by performing WGCNA, Random Forest, SVM-REF, correlation with SLEDAI and differential gene analysis. Receiver operating characteristic curves (ROCs) and AUC values were used to determine the clinical value. The expression level of the biomarker was verified by RT‒qPCR. Subsequently, functional enrichment analysis was utilized to identify biomarker-associated pathways. ssGSEA, CIBERSORT, xCell and ImmuCellAI algorithms were applied to calculate the sample immune cell infiltration abundance. Single-cell data were analyzed for gene expression specificity in immune cells. Finally, the transcriptional regulatory network of the biomarker was constructed, and the corresponding therapeutic drugs were predicted. Results: Multiple algorithms were screened together for a unique marker gene, MX2, and expression analysis of multiple datasets revealed that MX2 was highly expressed in SLE compared to the normal group (all P < 0.05), with the same trend validated by RT‒qPCR (P = 0.026). Functional enrichment analysis identified the main pathway of MX2 promotion in SLE as the NOD-like receptor signaling pathway (NES=2.492, P < 0.001, etc.). Immuno-infiltration analysis showed that MX2 was closely associated with neutrophils, and single-cell and transcriptomic data revealed that MX2 was specifically expressed in neutrophils. The NOD-like receptor signaling pathway was also remarkably correlated with neutrophils (r >0.3, P < 0.001, etc.). Most of the MX2-related interacting proteins were associated with SLE, and potential transcription factors of MX2 and its related genes were also significantly associated with the immune response. Conclusion: Our study found that MX2 can serve as an immune-related biomarker for predicting the diagnosis and disease activity of SLE. It activates the NOD-like receptor signaling pathway and promotes neutrophil infiltration to aggravate SLE.

Immunoglobulin D (IgD) and IgD receptor expression in diffuse large B-cell lymphoma.

Objective: Immunoglobulin D (IgD) levels are often elevated in patients with autoimmune diseases. However, the oncogenic activities of IgD and IgD receptor (IgDR) in diffuse large B-cell lymphoma (DLBCL) have not been reported in detail. Therefore, we aimed to investigate the expression of IgD and IgDR in patients with DLBCL. Methods: Membrane IgD (mIgD) and IgDR expression in tissue samples was analyzed using IHC, mIgD and IgDR expression on peripheral blood mononuclear cells (PBMCs) was analyzed by FCM, and secreted IgD (sIgD) level was analyzed by ELISA. Fisher's exact test and Spearman correlation analysis were used to evaluate the relationship between IgD, IgDR, and clinical parameters. Results: The pathological lymph nodes of 34 patients with DLBCL were studied, and mIgD and IgDR expression was found in 16 and 19 patients. mIgD and IgDR expression was upregulated in patients with DLBCL and mIgD expression was significantly associated with IgDR expression. Further correlation analysis showed that mIgD expression was correlated with serum ß2-MG level and Hans algorithm as germinal center B (GCB), whereas IgDR expression correlated with serum LDH level, IPI score and GCB. ELISA showed that sIgD level was significantly increased in DLBCL patients and it correlated with serum ß2-MG and LDH levels. FCM showed that mIgD and IgDR expression in PBMCs of patients with DLBCL was significantly higher than that in healthy controls. Conclusion: Our findings suggest that overexpression of IgD and IgDR is an abnormal activation state in DLBCL.

Regulatory effects of paeoniflorin-6'-O-benzene sulfonate (CP-25) on dendritic cells maturation and activation via PGE2-EP4 signaling in adjuvant-induced arthritic rats.

Rheumatoid arthritis (RA) is a chronic, systemic autoimmune disease. Dendritic cells (DCs) are one of the most powerful antigen-presenting cells, and they play an important role in RA pathogenesis. Prostaglandin E2 (PGE2) is a potent lipid mediator that can regulate the maturation and activation of DCs, but the molecular mechanisms have not been elucidated. In this study, both in vitro and in an RA rat model, we investigated the mechanisms involved by focusing on PGE2-mediated signaling and using a novel anti-inflammatory compound, paeoniflorin-6'-O-benzene sulfonate (CP-25). PGE2 combined with tumor necrosis factor-α promoted DC maturation and activation through EP4-cAMP signaling. Treatment with CP-25 increased the endocytic capacity of DCs induced by PGE2. CP-25 inhibited the potency of DCs induced by the EP4 receptor agonist, CAY10598, to stimulate allogeneic T cells. Consistent with these findings, the CAY10598-induced upregulation of DC surface activation markers and production of IL-23 was significantly inhibited by CP-25 in a concentration-dependent manner. In vivo administration of CP-25 alleviated adjuvant arthritis (AA) in rats through inhibition of DC maturation and activation. Our results indicate that PGE2-EP4-cAMP signal hyperfunction can lead to abnormal activation of DC functions, which correlates with the course of disease in AA rats and provides a possible treatment target. The inhibition of DC maturation and activation by CP-25 interference of the PGE2-EP4 pathway may significantly contribute to the immunoregulatory profile of CP-25 when used to treat RA and other immune cell-mediated disorders.

CP-25 reverses prostaglandin E4 receptor desensitization-induced fibroblast-like synoviocyte dysfunction via the G protein-coupled receptor kinase 2 in autoimmune arthritis.

Paeoniflorin-6'-O-benzene sulfonate (CP-25) is a novel compound derived from paeoniflorin that has been demonstrated to have therapeutic effects in a rat model of rheumatoid arthritis (RA). However, the underlying mechanism has not been elucidated to date. We explored this mechanism in the present study by treating rats with adjuvant arthritis (AA) with CP-25. We found that the membrane EP4 protein level was downregulated; whereas, GRK2 was upregulated, in fibroblast-like synoviocyte (FLS)s of AA rats. Prostaglandin (PGE)2 stimulated FLS proliferation and enhanced the membrane EP4 receptor protein level; the latter was reversed by the administration of an EP4 receptor agonist, whereas the membrane GRK2 protein level gradually increased. The changes in the EP4 receptor and GRK2 expression were enhanced by TNF-α, and the former was accompanied by an alteration in the cyclic (c)AMP level. The EP4 receptor agonist stimulation increased the association between GRK2 and the EP4 receptor. GRK2 knockdown abrogated the abnormalities in FLS proliferation. The CP-25 treatment (100 mg/kg) suppressed joint inflammation with an efficacy that was similar to that of methotrexate. This finding was associated with EP4 upregulation and GRK2 downregulation in FLSs. Thus, GRK2 plays an important role in the abnormal FLS proliferation observed in AA possibly by promoting EP4 receptor desensitization and decreasing the cAMP level. Our results demonstrate that CP-25 has therapeutic potential for the treatment of human RA via GRK2 regulation.

The immunoglobulin D Fc receptor expressed on fibroblast-like synoviocytes from patients with rheumatoid arthritis contributes to the cell activation.

Immunoglobulin IgD might play an important role in autoimmune diseases, but the function of IgD has remained elusive, despite multiple attempts to define its biological function. Fibroblast-like synoviocytes (FLSs) are specialized cells of the synovium that play a key role in the pathogenesis of rheumatoid arthritis (RA). In this study we explored the possible roles of excessive IgD expression on the function of FLSs from RA patients (RA-FLSs). We showed that IgD Fc receptor (IgDR) was constitutively expressed on FLSs, and was significantly elevated in RA-FLSs compared with FLSs prepared from synovial tissues of healthy controls (HC-FLSs). Furthermore, IgDR was mainly detected on the cell surface and in the cytoplasm. We further detected the intrinsic binding affinity of IgD to IgDR on HC-FLSs with an equilibrium dissociation constant (KD) of 0.067 nmol/L. Incubation of RA-FLSs with IgD (1-10 µg/mL) for 48 h dose-dependently promoted the expression of IgDR, and stimulated the production of inflammatory cytokines and chemokines, such as IL-1ß, IL-6, monocyte chemotactic protein (MCP)-1, TNF-α and receptor activator of nuclear factor-κB ligand (RANKL), thus potentially contributing to IgD-IgDR crosslinking. Moreover, incubation with IgD (0.1-10 µg/mL) for 48 h dose-dependently enhanced viability for both HC-FLSs and RA-FLSs. Our results demonstrate that IgDR is expressed on RA-FLSs and contributes to the activation of FLSs, and suggest that IgD-IgDR is a potential novel immunotherapeutic target for the management of RA.

Paeoniflorin regulates the function of human peripheral blood mononuclear cells stimulated by rhIL-1ß by up-regulating Treg expression.

The aim of the present study was to investigate the effect of paeoniflorin (Pae) on recombinant human interleukin-1ß (rhIL-1ß)-stimulated human peripheral blood mononuclear cells (PBMCs) in vitro. PBMCs were collected by Ficoll density gradient centrifugation and were co-cultured with rhIL-1ß for different time periods. The proliferation response was determined by a cell counting kit-8 (CCK-8) assay. The production of IL-17 and IL-10 was measured by enzyme-linked immunosorbent assay (ELISA). The percentage of CD4(+)CD25(+)Foxp3(+) regulatory T cells (Treg) was detected by flow cytometry analysis. These results indicated that rhIL-1ß stimulation induced the proliferation of PBMCs in a concentration- and time-dependent manner; it also increased the level of IL-17 and decreased the level of IL-10 in a concentration-dependent manner. The flow cytometry analysis demonstrated that the stimulation of rhIL-1ß significantly downregulated the percentage of CD4(+)CD25(+)Foxp3(+) Treg in CD4(+) T cells. However, administration of Pae significantly suppressed the proliferation response of rhIL-1ß-induced PBMCs and regulated the secretion function of IL-17 and IL-10. Additional experiments demonstrated that Pae treatment significantly reduced rhIL-1ß-induced decreases in PBMCs CD4(+)CD25(+)Foxp3(+) subpopulation numbers. These results suggest that the anti-inflammatory action of Pae is attributable to its regulation of IL-17/IL-10 secretion and Treg expression.

The role of prostaglandin E2 receptor signaling of dendritic cells in rheumatoid arthritis.

Prostaglandin E2 (PGE2), a very potent lipid mediator produced from arachidonic acid (AA) through the action of cyclooxygenase (COX) enzymes, is implicated in the regulation of dendritic cell (DC) functions such as differentiation ability, cytokine-producing capacity, Th-cell polarizing ability, migration and maturation. DCs are the most potent antigen-presenting cells and play major roles in both the induction of primary immune responses and tolerance. It is well established that PGE2 functions significantly in the pathogenesis of rheumatoid arthritis (RA). Although the role of PGE2 in RA has been studied extensively, the effects of PGE2 on DC biology and the role of DCs in RA have not become the focus of investigation until recently. Here, we summarize the latest progress in PGE2 research with respect to DC functions, as well as the role of PGE2 receptor signaling of DCs in the pathogenesis of RA.

Total glucosides of paeony inhibit the proliferation of fibroblast-like synoviocytes through the regulation of G proteins in rats with collagen-induced arthritis.

The aim of this study was to investigate the expression of G proteins in fibroblast-like synoviocytes (FLSs) from rats with collagen-induced arthritis (CIA) and to determine the effect of total glucosides of paeony (TGP). CIA rats were induced with chicken type II collagen (CCII) in Freund's complete adjuvant. The rats with experimental arthritis were randomly separated into five groups and then treated with TGP (25, 50, and 100mg/kg) from days 14 to 35 after immunization. The secondary inflammatory reactions were evaluated through the polyarthritis index and histopathological changes. The level of cyclic adenosine monophosphate (cAMP) was measured by radioimmunoassay. The FLS proliferation response was determined by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. The toxin-catalyzed ADP-ribosylation of G proteins was performed through autoradiography. The results show that TGP (25, 50, and 100mg/kg) significantly decreased the arthritis scores of CIA rats and improved the histopathological changes. TGP inhibited the proliferation of FLSs and increased the level of cAMP. Moreover, the FLS proliferation and the level of Gαi expression were significantly increased, but the level of Gαs expression was decreased after stimulation with IL-1ß (10ng/ml) in vitro. TGP (12.5 and 62.5µg/ml) significantly inhibited the FLS proliferation and regulated the balance between Gαi and Gαs. These results demonstrate that TGP may exert its anti-inflammatory effects through the suppression of FLS proliferation, which may be associated with its ability to regulate the balance of G proteins. Thus, TGP may have potential as a therapeutic agent for the treatment of rheumatoid arthritis.

Paeoniflorin inhibits function of synoviocytes pretreated by rIL-1α and regulates EP4 receptor expression.

ETHNOPHARMACOLOGICAL RELEVANCE: To investigate the effect of the Paeoniflorin (Pae), a main active component of total glucosides of paeony (TGP) extracted from the root of Paeonia lactiflora, on regulation of synoviocytes cultured from rats collagen-induced arthritis (CIA) in vitro. MATERIALS AND METHODS: CIA was induced in male Sprague-Dawley rats immunized with chicken type II collagen (CCII) in Freund's complete adjuvant. The levels of interleukin-1 (IL-1), tumor necrosis factor α (TNF-α), prostaglandin E(2) (PGE(2)) and cyclic adenosine monophosphate (cAMP) were measured by radioimmunoassay. The proliferation responses was determined by the 3-(4,5-2dimethylthiazal-2yl) 2,5-diphenyltetrazoliumbromide (MTT) assay. Expression of E-prostanoid (EP(4)) receptor was detected by Western blotting technique. RESULTS: Treatment of Pae (2.5, 12.5, 62.5 µg/ml) significantly decreased the production of IL-1 and TNF-α. Recombinant interleukin-1 (rIL-1α) (10 ng/ml) apparently stimulated synoviocyte, thymocyte and splenocyte proliferation, and Pae (12.5, 62.5 µg/ml) inhibited abnormal proliferation responses stimulated by rIL-1α. Moreover, rIL-1α time- and concentration-dependently increased production of PGE(2). The production of PGE(2) produced by synoviocytes from CIA rats significantly inhibited by administration of Pae (12.5, 62.5 µg/ml). rIL-1α (10 ng/ml) decreased cAMP of synoviocytes cells treated for 24h. Similarly rIL-1α (0.1, 1, 10 ng/ml) induced a concentration-dependent decrease in the production of cAMP at 24h. Pae (12.5, 62.5 µg/ml) increased the production of cAMP in synoviocytes. The immunoblot, Pae (12.5, 62.5 µg/ml) apparently increased the expression of EP(4) receptor in synoviocytes stimulated by rIL-1α (10 ng/ml). CONCLUSIONS: The present study indicates that Pae might exert its anti-inflammatory effects through suppressing synoviocytes function and regulating immune cells responses in CIA rats, which might be associated with its ability to up-regulate the E-prostanoid (EP(4)) receptor protein expression and modulate intracellular cAMP level.

Effects and mechanisms of Cryptotanshinone on rats with adjuvant arthritis.

BACKGROUND: Cryptotanshinone (CT) is the major active constituent of Salvia miltiorrhiza Bunge. The present study was carried out to investigate the effects of CT on rats with adjuvant arthritis (AA). METHODS: AA was induced by the metatarsal footpad injection with complete Freund's adjuvant in male Sprague-Dawley rats. The secondary inflammatory reaction was evaluated by hind paw swelling and the polyarthritis index. Activity of interleukin-1 (IL-1) was detected by the concanavalin A-induced thymocytes proliferation assay. The lymphocytes proliferation and IL-2 production were assayed by 3-(4,5-2dimethylthiazal-2yl)2,5-diphenyltetrazoliumbromide (MTT) and activated mouse splenocytes proliferation, respectively. RESULTS: Intragastric administration of CT (50 and 100 mg/kg) significantly decreased secondary inflammatory reactions and increased the spleen and thymus index. There was a marked immunologic and inflammatory response in the AA model, which was accompanied by the decrease of thymocyte proliferation and IL-2 production as well as the increase of IL-1 production. CT apparently enhanced thymocyte proliferation and decreased IL-1 production in AA rats. CONCLUSION: These results indicate that CT may exert its anti-inflammatory and immunoregulatory effects through inhibiting lymphocyte proliferation and production of pro-inflammatory mediators.

Effects of cryptotanshinone on immune functions in rats with adjuvant arthritis.

BACKGROUND: Cryptotanshinone (CT) was originally isolated from the dried roots of Salvia militorrhiza, an herb that is used extensively in Asian medicine and the extracts of this herb have been used in the treatment of several pathologies, including cardiovascular diseases, hematological abnormalities, hepatitis, and hyperlipidemia, but no studies had been carried on the treatment for rheumatic diseases with it. This study aimed to investigate the effects of cryptotanshinone on immune functions in rats with adjuvant arthritis (AA). METHODS: Complete Freund's adjuvant was used to induce AA in rats. Thymus and spleen was aseptically taken from normal rats and the AA rats. Then a thymus lymphoid cell suspension, splenic lymphoid cell suspension and peritoneal macrophage cell suspension were prepared. After adding CT (0.1 microg/ml, 1.0 microg/ml, 10 microg/ml, 100 microg/ml, 1000 microg/ml) into the suspension, T and B lymphocytes proliferation was determined by 3-(4,5-2 dimethylthiazal-2yl)2,5-diphenyltetrazoliumbromide (MTT) assay. And the activities of interleukin-1 (IL-1) and IL-2 were measured by the mouse lymphocytes proliferation assay. RESULTS: Thymic T and splenic B lymphocyte proliferation of the AA rat was significantly lower, and could be stored through using CT in vitro. CT (100 microg/ml and 1000 microg/ml) increased T or B lymphocytes proliferation in vitro (P < 0.01). In AA rats, the levels of IL-1 released by abdominal PMPhi significantly increased whereas the level of IL-2 released by T cells decreased in vitro. CT (1000 microg/ml) decreased the production of IL-1 and promoted production of IL-2 in vitro (P < 0.05). CONCLUSIONS: CT can ameliorate the abnormal immunological functions in AA rats.

Effects and mechanisms of total glucosides of paeony on adjuvant arthritis in rats.

Total glucosides of paeony (TGP) is the major active constituent of Paeonia lactiflora Pall. The present study was carried out to investigate the effects of TGP on adjuvant arthritis (AA) of rat and its possible mechanisms. AA was induced by metatarsal footpad injection with complete Freund's adjuvant in male Sprague-Dawley rats. The secondary inflammatory reaction was evaluated by hind paw swelling, polyarthritis index. Activity of interleukin-1 (IL-1) was detected by Con A-induced thymocytes proliferation of C57BL/6J mice assay. The tumor necrosis factor alpha (TNFalpha), prostaglandin E(2) (PGE(2)) and cyclic adenosine monophosphate (cAMP) levels in synoviocytes were assessed by radioimmunoassay (RIA). PGE(2) receptors, EP2 and EP4, were analyzed by Western blot analysis. The level of IL-6 was measured by ELISA. Intragastric administration of TGP (50,100 mg/kg) significantly decreased secondary inflammatory reaction in AA rats. Suppressing the activity of IL-1 and TNFalpha, decreased PGE(2) and increased cAMP levels in synoviocytes of AA rats were observed after administration of TGP. In the immunoblot analysis, TGP could up-regulate the expression of EP2 and EP4. These results showed TGP significantly inhibited the progression of AA, and the inhibitory effects might be associated with its ability to mediate the level of cAMP and inhibit the production of IL-1, TNFalpha, IL-6 and PGE(2) from activated synoviocytes.

Interleukin-1 receptor antagonist intervenes in signaling between different types of synoviocytes in rats with adjuvant arthritis.

AIM: To investigate the mechanisms of interleukin-1 receptor antagonist (IL-1ra) in the treatment of adjuvant arthritis (AA). METHODS: AA was induced in rats by treatment with Freunds complete adjuvant (FCA). Rats were given an intracutaneous injection of IL-1ra (2.5, 10, 40 mg/kg, 3 times per day) from d 14 to d 21 after immunization. Synoviocyte proliferation and the activity of IL-1 were determined by using MTT assay. Tumor necrosis factor alpha (TNF-alpha) and prostaglandin E(2) (PGE(2)) concentrations were measured by radioimmunoassay. The ultrastructure of synoviocytes was observed by using a transmission electron microscope. Phosphorylation of c-Jun N-terminal kinase (JNK), extracellular regulating kinase (ERK) and p38 kinase were detected by Western blot analysis. RESULTS: IL-1ra (10 and 40 mg/kg, ic, d 14-21) modulated the secondary inflammatory reaction (P < 0.01), ultrastructure of synoviocytes and mitogen-activated protein kinase (MAPK) phosphorylation in AA rats. The administration of IL-1ra (10 and 40 mg/kg, ic, d 14-21) in AA rats significantly decreased the production of IL-1, PGE2 and TNF-alpha by macrophage-like synoviocytes (MLS) (P < 0.01). IL-1ra (2.5 mg/kg) also decreased the production of PGE2 (P < 0.01) and TNF-alpha (P < 0.05) by MLS in AA rats. The increased phosphorylation of MAPK and cell proliferation in fibroblast-like synoviocytes (FLS) stimulated by supernatants of MLS in AA rats was also inhibited by IL-1ra (10 and 40 mg/kg, ic, d 14-21). CONCLUSION: IL-1ra has anti-inflammatory effects because it modulates the ultrastructure of synoviocytes, decreases the production of pro-inflammatory mediators by MLS, and inhibits the phosphorylation of MAPK in FLS.