Immunotherapy of Rheumatoid Arthritis Targeting Inflammatory Cytokines and Autoreactive T Cells

CaP-based anti-inflammatory HIF-1α siRNA-encapsulating nanoparticle for rheumatoid arthritis therapy

Rheumatoid arthritis (RA) is a common inflammatory disease and its treatment is largely limited by drug ineffectiveness or severe side effects. In RA progression, multiple signalling pathways, such as hypoxia-inducible factor (HIF)-1α, nuclear factor kappa B (NF-κB), and mitogen-activated protein kinase (MAPK) pathways, act synergistically to maintain the inflammatory response. To downregulate HIF-1α, NF-κB, and MAPK expression, we proposed HIF-1α siRNA-loaded calcium phosphate nanoparticles encapsulated in apolipoprotein E3-reconstituted high-density lipoprotein (HIF-CaP-rHDL) for RA therapy. Here, we evaluated the potential of CaP-rHDL nanoparticles in RA therapy using a murine macrophage line (RAW 264.7) and a collagen-induced arthritis (CIA) mouse model. The CaP-rHDL nanoparticles showed significant anti-inflammatory effects along with HIF-1α knockdown and NF-κB and MAPK signalling pathway inhibition in lipopolysaccharide-activated macrophages. Moreover, they inhibited receptor activator of NF-κB ligand (RANKL)-induced osteoclast formation. In CIA mice, their intravenous administration resulted in high accumulation at the arthritic joint sites, and HIF-CaP-rHDL effectively suppressed inflammatory cytokine secretion and relieved bone erosion, cartilage damage, and osteoclastogenesis. Thus, HIF-CaP-rHDL demonstrated great potential in RA precision therapy by inhibiting multiple inflammatory signalling pathways.

1,7-Dihydroxy-3,4-Dimethoxyxanthone Inhibits Lipopolysaccharide-Induced Inflammation in RAW264.7 Macrophages by Suppressing TLR4/NF-κB Signaling Cascades

Securidaca inappendiculata Hassk. is a traditional Chinese anti-rheumatic herbal medicine native to southern China. In this study, we identified a possible TLR4 inhibitor from this plant. General effects of its xanthone-rich fraction (XRF) on inflammation in vitro were investigated by immunoblotting experiments performed on lipopolysaccharides (LPS)-treated RAW264.7 cells, and the possible ligand of TLR4 within was screened out by analyzing chemical composition differences of the XRF containing cell culture medium under different inflammatory circumstances. The interaction between ligand and TLR4 was validated by cellular thermal shift assay (CETSA) and molecular docking simulation, and TLR4/NF-κB pathway status was investigated by immunoprecipitation, ELISA, immunofluorescence, dual-luciferase reporter, and immunoblotting experiments. Treatment with XRF resulted in significant decrease in p-p65 and p-JNK, and the signal accounting for 1,7-dihydroxy-3,4-dimethoxyxanthone (XAN) at 12.5 min with mass of 289.29 was greatly decreased in XRF containing medium after LPS stimulus because of enhanced interaction with increased TLR4. CETSA and molecular docking simulation demonstrated that XAN could bind to TLR4 directly on a smooth region adjacent to its contact interface with MD-2. XAN treatment inhibited the dimerization of TLR4 and transcriptional activity of NF-κB in HEK293T cells and decreased p65 accumulation in nucleus and pro-inflammatory cytokines production in RAW264.7 cells receiving LPS treatment. Overall evidences suggest that XAN could be a selective TLR4 inhibitor with potent anti-inflammatory effects. Also, it indicated that xanthone derivatives could have promising clinical application in many immune-mediated inflammations by acting as TLR4 inhibitors.

T-614 Promotes Osteoblastic Cell Differentiation by Increasing Dlx5 Expression and Regulating the Activation of p38 and NF-κB

Rheumatoid arthritis (RA) is an autoimmune inflammatory disease characterized by bone loss. Degree of inflammation has been identified as an important initiator of skeletal damage in RA. Iguratimod (T-614) is an anti-inflammatory agent which has been reported to show the inhibitory effect of bone destruction in RA. However, the role of T-614 in osteoblast differentiation is still not clear. In this study, we intended to find the effect of T-614 on the osteogenesis process. We detected osteogenesis markers and transcription factors associated with osteoblastic lineage and bone formation in the culture of mesenchymal stem cells which differentiate osteoblast. The contents and activity of alkaline phosphatase, levels of collagen type I and bone gla protein, and calcium nodule formation were increased significantly after T-614 treated. Meanwhile, the mRNAs expressions of Osterix and Dlx5 were also found to be increased significantly by real-time PCR. The changes of levels of phosphorylation of p38 and NF-κB were also detected by Western blot. The results showed that T-614 promotes osteoblastic differentiation by increasing the expression of Osterix and Dlx5 and increasing the activation of P38. T-614 could advance the ectopic expression of NF-κB to suppress inflammation, which indirectly inhibits the damage of the osteoblasts.

Immunosuppressive Effect of Geniposide on Mitogen-Activated Protein Kinase Signalling Pathway and Their Cross-Talk in Fibroblast-Like Synoviocytes of Adjuvant Arthritis Rats

Geniposide (GE), an iridoid glycoside compound derived from Gardenia jasminoides Ellis fruit, is known to have anti-inflammatory and immunoregulatory activities. The aim of this study was to investigate the protective mechanism of GE in the regulation of the mitogen-activated protein kinase (MAPK) signalling pathway and the cross-talk among the MAPK signalling pathway in fibroblast-like synoviocytes (FLS) of adjuvant arthritis (AA) rats. AA was induced by injecting with Freund's complete adjuvant. Male SD rats and FLS were subjected to treatment with GE (30, 60 and 120 mg/kg) in vivo from day 14 to 21 after immunization and GE (25, 50 and 100 μg/mL) in vitro, respectively. The proliferation of FLS was assessed by MTT. IL-4, IL-17, IFN-γ, and TGF-β1 were determined by ELISA. Key proteins in the MAPK signalling pathway were detected by Western blot. GE significantly reduced the proliferation of FLS, along with decreased IFN-γ and IL-17 and increased IL-4 and TGF-β1. In addition, GE decreased the expression of p-JNK, p-ERK1/2 and p-p38 in FLS of AA rats. Furthermore, disrupting one MAPK pathway inhibited the activation of other MAPK pathways, suggesting cross-talk among MAPK signalling. In vivo study, it was also observed that GE attenuated histopathologic changes in the synovial tissue of AA rats. Collectively, the mechanisms by which GE exerts anti-inflammatory and immunoregulatory effects may be related to the synergistic effect of JNK, ERK1/2 and p38. Targeting MAPK signalling may be a new therapeutic strategy in inflammatory/autoimmune diseases.

Therapeutic effect of ergotope peptides on CIA by down-regulation of inflammatory and Th1/Th17 responses and induction of regulatory T cells

Rheumatoid arthritis (RA) is a systemic autoimmune disease that results in a chronic and inflammatory disorder. Dynamic balance of helper T cells (Th)1, Th17 and regulatory T cells (Treg) is broken in RA. Since there is no cure for RA at present, it's necessary to find a truly effective and convenient treatment. Several studies intended to induce ergotopic regulation to treat autoimmune diseases. This study was undertaken to find the potential ergotope peptides and investigate its effect in treating the animal model of RA and their underlying regulatory mechanisms. Firstly, we selected the functional ergotope peptides from 25 overlapping peptides derived from interlukin(IL)-2 receptor (IL-2R) α chain, and then used these peptides to treat collagen-induced arthritis (CIA). The study showed ergotope peptides as immunomodulatory factors with great benefits at the clinical and pathologic levels. This effect was associated with the inhibition of type II collagen (CII)-specific proliferation and autoantibody production as well as the induction of anti-ergotypic immune response, the down-regulation of both Th1 and Th17 cells and their related components, and the emergence of Treg cells that had suppressive actions on autoreactive T cells. We also proved that cytotoxic T lymphocyte associated antigen-4 (CTLA-4) and IL-10 are two important mediators which are critical to Treg suppressive function. The inhibition of Th1 and Th17 in established CIA could be attributed to ergotope induced Treg cells. Our findings reveal that ergotope peptides induce regulatory immune responses and restore immune tolerance, suggesting ergotope peptides treatment appears to be a novel approach to the therapy of RA patients and has a good application prospect with cheap, effective, convenient, wide-spectrum features.

IL-1β at the crossroad between rheumatoid arthritis and type 2 diabetes: may we kill two birds with one stone?

Although in the past the prevention of joint destruction in rheumatoid arthritis (RA) was strongly emphasized, now a great interest is focused on associated comorbidities in these patients. Multiple data suggest that a large percentage of RA patients are affected by Type 2 Diabetes (T2D), whose incidence has reached epidemic levels in recent years, thus increasing the health care costs. A better knowledge about the pathogenesis of these diseases as well as the mechanisms of action of drugs may allow both policy designers and physicians to choose the most effective treatments, thus lowering the costs. This review will focus on the role of Interleukin (IL)-1β in the pathogenesis of both the diseases, the efficacy of IL-1 blocking molecules in controlling these diseases, and will provide information suggesting that targeting IL-1β, in patients affected by both RA and T2D, may be a promising therapeutic choice.

Anti-inflammatory effects of recombinant human PDCD5 (rhPDCD5) in a rat collagen-induced model of arthritis

Programmed cell death 5 (PDCD5) was first identified as a gene upregulated in cells undergoing apoptosis. We recently demonstrated the inhibitory effect of PDCD5 on experimentally induced autoimmune encephalomyelitis. In this study, we investigated the anti-inflammatory effects of recombinant human PDCD5 (rhPDCD5) in a rat collagen-induced arthritis (CIA) model. We find that vaccination of collagen II (CII) induced CIA rats with rhPDCD5 significantly delayed the occurrence and reduced the severity of CIA rats. rhPDCD5 also restored the loss of Foxp3⁺ regulatory T (Treg) cells and decreased the population of Th1 and Th17 in CIA rats. Simultaneously, rhPDCD5 treatment suppressed the production of pro-inflammatory cytokines (interleukin (IL)-6, IL-17A, tumor necrosis factor-α (TNF-α), and interferon gamma (IFN-γ)) and increased the secretion of anti-inflammatory cytokines (transforming growth factor beta 1 (TGF-β1) and IL-10) in CIA rats. In addition, rhPDCD5 inhibited the ability of CII to induce proliferation of splenocytes and lymph node cells (LNCs) and promoted the CII-activated CD4⁺ cell apoptosis. These results of rhPDCD5-treated CIA rats were similar with those of recombinant human TNF-α receptor IgG Fc (rhTNFR:Fc). Thus, to our knowledge, we provide the first evidence that rhPDCD5 may be an efficient approach to diminishing exacerbated immune responses in CIA, indicating its therapeutic potential in the treatment of rheumatoid arthritis and other autoimmune diseases.

DC-Based Immunotherapy Combined with Low-Dose Methotrexate Effective in the Treatment of Advanced CIA in Mice

We have previously demonstrated that semimature dendritic cell- (smDC-) based immunotherapy is effective for the treatment of collagen-induced arthritis (CIA) prior to disease onset. In the present study, we examined the efficacy of combination therapy with smDCs and methotrexate (MTX) in advanced CIA with a score of 2-3. Combination therapy with low-dose MTX and type II collagen- (CII-) pulsed smDCs (CII-smDCs) was more effective in inhibiting disease progression than high or low-dose MTX alone or a combination of high dose MTX and CII-smDCs. The effect of CII-smDCs alone was also comparable to the combination therapy. CD4⁺Foxp3⁺ Treg populations and IL-10 secretion markedly increased, and CII-specific autoreactive T cells decreased in mice treated with CII-smDCs alone or in combination with MTX. Combination therapy reduced the secretion of interferon-γ (IFN-γ) and IL-17 with little influence on the IL-4 secretion in the mixed leukocyte reaction. These results imply that the combination therapy with low-dose MTX and smDCs is effective in controlling advanced CIA by enhancing Treg population and suppresses antigen-specific Th1/Th17 immunity, rather than initiating Th1 to Th2 immune deviation. Our findings provide a better understanding of the DC therapy in combination with MTX for the treatment of patients with rheumatoid arthritis (RA).

Clinical biomarkers and pathogenic-related cytokines in rheumatoid arthritis

Rheumatoid arthritis (RA) is a common autoimmune disease with unknown etiology and pathogenesis. Although major therapeutic advances have been made in recent years, there is no cure for the disease. Current medications mainly reduce inflammation in order to relieve pain and slow joint damage, but many have potentially serious side effects. Therefore, to find specific biomarkers will benefit both RA patients to find relief from the disease and physicians to monitor the disease development. A number of biomarkers have been discovered and used clinically, and others are still under investigation. The autoantibodies, which are widely used in diagnosis and prognosis, novel biomarkers, which reflect clinical disease activity, and newly found biomarkers and pathogenic-related cytokines are discussed in this review.

Endogenous activation of adaptive immunity: tenascin-C drives interleukin-17 synthesis in murine arthritic joint disease

OBJECTIVE

Rheumatoid arthritis is characterized by persistent synovial inflammation and progressive joint destruction, which are mediated by innate and adaptive immune responses. Cytokine blockade successfully treats some patient subsets; however, ∼50% do not respond to this approach. Targeting of pathogenic T lymphocytes is emerging as an effective alternative/complementary therapeutic strategy, yet the factors that control T cell activation in joint disease are not well understood. Tenascin-C is an arthritogenic extracellular matrix glycoprotein that is not expressed in healthy synovium but is elevated in the rheumatoid joint, where high levels are produced by myeloid cells. Among these cells, tenascin-C expression is most highly induced in activated dendritic cells (DCs). The aim of this study was to examine the role of tenascin-C in this cell type.

METHODS

We systematically compared the phenotype of DCs isolated from wild-type mice or mice with a targeted deletion of tenascin-C by assessing cell maturation, cytokine synthesis, and T cell polarization.

RESULTS

Dendritic cells derived from tenascin-C-null mice exhibited no defects in maturation; induction of the class II major histocompatibility complex and the costimulatory molecules CD40 and CD86 was unimpaired. Dendritic cells that did not express tenascin-C, however, produced lower levels of inflammatory cytokines than did cells from wild-type mice and exhibited specific defects in Th17 cell polarization. Moreover, tenascin-C-null mice displayed ablated levels of interleukin-17 in the joint during experimental arthritis.

CONCLUSION

These data demonstrate that tenascin-C is important in DC-mediated polarization of Th17 lymphocytes during inflammation and suggest a key role for this endogenous danger signal in driving adaptive immunity in erosive joint disease.

New insights into chronic inflammation-induced immunosuppression

Chronic inflammation is a common factor linking various pathologies that differ in their etiology and physiology such as cancer, autoimmune diseases, and infections. At a certain stage of each of these diseases, while the chronic inflammation proceeds, some key players of the immune system become immunosuppressed as natural killer (NK) cells and T cells. The suppressive environment induced during chronic inflammation is governed by a complex processes characterized by the accumulation and activation of immune suppressor cells, pro-inflammatory cytokines, chemokines, growth and angiogenic factors, and by the activation of several inflammatory signaling pathways mediated predominantly by NFκB and STAT3 transcription factors. A substantial body of evidence supports the notion that the development of a suppressive environment during chronic inflammation limits the success of immune-based and conventional therapies, skewing the balance in favor of a developing pathology. Thus, appropriate, well-designed and fine tuned immune interventions that could resolve inflammatory responses and associated immunosuppression could enhance disease regression and reinforce successful responses to a given therapy. This review describes the interrelationship between chronic inflammation and induced immunosuppression, and explains the current evidence linking inflammation and pathological processes, as found in cancer. We further highlight potential strategies, harnessing the immunosuppressive environment in treating autoimmune diseases and facilitating transplantation. In parallel, we emphasize the use of modalities to combat chronic inflammation-induced immunosuppression in cancer, to enhance the success of immune-based therapies leading to tumor regression. In both cases, the urgent necessity of identifying biomarkers for the evaluation of host immune status is discussed, with the goal of developing optimal personalized treatments.

Serum levels of soluble CD26 and CD30 and their clinical significance in patients with rheumatoid arthritis

The aim of this study was to assess serum levels and clinical significance of soluble CD26 (sCD26) and soluble CD30 (sCD30) in patients with rheumatoid arthritis (RA). Forty-eight patients with RA and 30 healthy controls were enrolled. Serum sCD26 and sCD30 levels were measured using ELISA. Serum sCD26 levels were significantly lower (P = 0.011), whereas sCD30 levels were higher (P = 0.008) in patients with RA than controls. Serum levels of sCD30 correlated significantly with clinical and laboratory parameters of disease activity like erythrocyte sedimentation rate, C-reactive protein, disease activity scores-28 and health assessment questionnaire score; however, sCD26 levels did not correlate any of these activity parameters. These results suggest that serum sCD30 levels increased and correlated significantly with disease activity, indicating a novel follow-up parameter in RA. Serum levels of sCD26 may be lessen but not related to disease activity in RA.

Effect of cocoa-enriched diets on lymphocytes involved in adjuvant arthritis in rats

Cocoa and its flavonoids have potential anti-inflammatory properties in vitro and in acute inflammation models in vivo. The aim of the present study was to ascertain the effects of two cocoa-enriched diets on adjuvant arthritis (AA) in rats, considering not only clinical and biochemical inflammatory indices, but also antibody response and lymphocyte composition. Female Wistar rats were fed with a 5 or 10 % cocoa-enriched diet beginning 2 weeks before arthritis induction and until the end of the study. AA was induced by an intradermal injection of heat-killed Mycobacterium butyricum suspension. The hind-paw swelling (plethysmometry), serum anti-mycobacterial antibody concentration (ELISA), blood and inguinal lymph node lymphocyte subset percentage (flow cytometry), and IL-2, interferon γ and PGE₂ released from splenocytes (ELISA) were assessed. Although the cocoa diets had no significant effect on hind-paw swelling, a tendency to reduce it was observed at the end of the study. Cocoa-enriched diets were able to decrease the serum anti-mycobacterial antibody concentration and the splenocyte PGE2 production, as well as the proportion of T-helper (Th) lymphocytes in blood and regional lymph nodes, which probably includes cells responsible for the arthritic process. The cocoa diets prevented a decrease in the proportion of regulatory T-cells in blood and a disequilibrium between inguinal lymph node natural killer (NK) CD8⁺ and NK CD8⁻ subsets. In conclusion, the cocoa-enriched diets during AA were not able to significantly decrease joint inflammation but modified Th-cell proportions and prevented specific antibody synthesis.