Therapeutic role of a vaccine targeting RANKL and TNF-α on collagen-induced arthritis

Detection of anti-calreticulin antibody in the sera of Chinese patients with primary Sjögren syndrome

BACKGROUND

Primary Sjögren syndrome (pSjS) is one of the most prevalent systemic autoimmune diseases and characterized with hyperactivation of B cell and the abundant presence of autoantibodies in sera. The salivary gland epithelial cells (SGECs) release autoantigens to evoke autoimmunity through releasing elevated apoptosis or secreting autoantigen-containing exosomes, thus identifying autoantibodies directly to SGECs might provide insights into disease related biomarkers as well as further elucidating pathogenesis mechanisms. The present study was undertaken to identify autoantibodies to SGECs and to evaluate its clinical values in Chinese pSjS.

METHODS

Cell-based indirect immunofluorescence and immunostaining, two-dimensional electrophoresis and liquid chromatograph-tandem mass spectrometry were conducted to identify the autoantibodies to human salivary gland cell line A253 in pSjS sera. Enzyme-linked immunosorbent assay (ELISA) was applied to identify autoantibody titer in pSjS cohort and healthy controls. The prevalence and clinical significance of the identified autoantibodies was further assessed in pSjS population.

RESULTS

Anti-calreticulin (CALR) antibody was identified as a new autoantibody directly to SGECs in sera from pSjS patients. Anti-CALR antibody were detected in 37 of 120 pSjS patients (30.83 %) and 1 of 54 healthy controls (1.85 %). It was found in 40.85 % pSjS with anti-SSA positive, 53.85 % with anti-SSB positive, and 14.7 % in sero-negative pSjS. Anti-CALR antibody was associated with clinical manifestations including weight loss(p = 0.045), vasculitis (p = 0.031), and laboratory parameters including erythrocyte sedimentation rate (ESR) (r = 0.056, p = 0.021), Krebs von den Lungen-6 (KL-6) (r = 0.121, p = 0.035), IgG (r = 0.097, p < 0.001), IgG2 (r = 0.142, p = 0.022), IgG3 (r = 0.287, p < 0.001), fibrinogen (r = 0.084, p = 0.016), D-Dimer (r = 0.086, p = 0.012) and fibrinogen degradation production (r = 0.150, p = 0.002). The expression of CALR in salivary glands was related to lymphocytes infiltration into salivary glands in pSjS patients (r = 0.7076, p = 0.0034).

CONCLUSION

To our knowledge, this was the first study to investigate the prevalence and clinical significance of anti-CALR antibody in Chinses pSjS patients. The present study identified an autoimmune antibody, anti-CALR antibody, as a good autoimmune biomarker for sero-negative pSjS.

From vaccines to nanovaccines: A promising strategy to revolutionize rheumatoid arthritis treatment

Rheumatoid arthritis (RA) is a joint-related autoimmune disease that is difficult to cure. Most therapeutics act to alleviate the symptoms but not correct the causes of RA. Novel strategies that specifically target the causes are highly needed for RA management. Currently, early interruption of RA is increasingly suggested but the corresponding therapeutics are not available. Vaccines that have shown great success to combat infection, cancer, degenerative diseases, autoimmune diseases, etc. are ideal candidates for a new generation of anti-RA therapeutics to correct the causes and prevent RA or interrupt RA in early phases. Anti-RA vaccines can be divided into two major categories. One is to induce neutralizing antibodies and the other is to induce antigen-specific immune tolerance. The vaccines are inherently linked to nanotechnology because they usually need a biomacromolecule or carrier to provoke sufficient immune responses. In the past decade, designed nanocarriers such as nanoparticles, liposomes, nanoemulsion, etc., have been applied to optimize the vaccines for autoimmune disease treatment. Nanotechnology endows vaccines with a higher biostability, tunable in vivo behavior, better targeting, co-delivery with stimulatory agents, regulatory effects on immune responses, etc. In this review, unmet medical needs for RA treatment and anti-RA vaccinology are first introduced. The development of anti-RA therapies from vaccines to nanovaccines are then reviewed and perspectives on how nanotechnology promotes vaccine development and advancement are finally provided. In addition, challenges for anti-RA vaccine development are summarized and advantages of nanovaccines are analyzed. In conclusion, nanovaccines will be a promising strategy to revolutionize the treatment of RA by correcting the causes in an early phase of RA.

Artesunate inhibits osteoclastogenesis through the miR-503/RANK axis

Osteoporosis is a metabolic bone disease that is characterized by decreased bone density and strength due to excessive loss of bone protein and mineral content, which can be induced by increased osteoclast activity. Developing agents targeting osteoclast activation is considered to be the most effective method to reverse bone destruction and alleviate the pain caused by osteoporosis. MTT assay was conducted to detect the cell viability after artesunate treatment of RAW264.7 cells. TRACP staining and pit formation assays were performed to examine the TRACP-positive cells and pit-forming activity of osteoclasts. qRT-PCR and Western blot analysis were performed to assess the mRNA and protein expression levels of the osteoclastogenesis-related genes NFATc1, TRAP, and cathepsin k. The protein levels of RANK, p-Akt, p-p38, and p-ERK were examined by Western blotting. Luciferase reporter assay was conducted to determine whether miR-503 targeted RANK directly. Artesunate inhibited TRACP-positive cells and the pit-forming activity of osteoclasts. However, artesunate increased the expression of miR-503. Artesunate suppressed osteoclastogenesis-related gene expression and RANKL-induced activation of MAPKs and the AKT pathway. In addition, miR-503 inhibited RANK expression by directly targeting RANK during osteoclast differentiation. Artesunate inhibited osteoclastogenesis and osteoclast functions in vitro by regulating the miR-503/RANK axis and suppressing the MAPK and AKT pathways, which resulted in decreased expression of osteoclastogenesis-related markers.

A novel modified RANKL variant can prevent osteoporosis by acting as a vaccine and an inhibitor

BACKGROUND

The discovery of receptor activator of nuclear factor-ĸB ligand (RANKL) as the final effector in the pathogenesis of osteoporosis has led to a better understanding of bone remodeling. When RANKL binds to its receptor (RANK), osteoclastic differentiation and activation are initiated. Herein, we propose a strategy using a novel RANKL variant as a competitive inhibitor for RANKL. The RANKL variant activates LGR4 signaling, which competitively regulates RANK and acts as an immunogen that induces anti-RANKL antibody production.

METHODS

We modified the RANK-binding site on RANKL using minimal amino acid changes in the RANKL complex and its counterpart receptor RANK and tried to evaluate the inhibitory effects on osteoclastogenesis.

RESULTS

The novel RANKL variant did not bind RANK in osteoclast progenitor cells, but activated LGR4 through the GSK3-β signaling pathway, thereby suppressing activated T cell cytoplasmic nuclear factor calcineurin-dependent 1 (NFATc1) expression and activity during osteoclastogenesis. Our RANKL variant generated high levels of RANKL-specific antibodies, blocked osteoclastogenesis, and inhibited osteoporosis in ovariectomized mouse models. Generated anti-RANKL antibodies showed a high inhibitory effect on osteoclastogenesis in vivo and in vitro.

CONCLUSIONS

We observed that the novel RANKL indeed blocks RANKL via LGR4 signaling and generates anti-RANKL antibodies, demonstrating an innovative strategy in the development of general immunotherapy.

Peptide-Based Vaccination Therapy for Rheumatic Diseases

Rheumatic diseases are extremely heterogeneous diseases with substantial risks of morbidity and mortality, and there is a pressing need in developing more safe and cost-effective treatment strategies. Peptide-based vaccination is a highly desirable strategy in treating noninfection diseases, such as cancer and autoimmune diseases, and has gained increasing attentions. This review is aimed at providing a brief overview of the recent advances in peptide-based vaccination therapy for rheumatic diseases. Tremendous efforts have been made to develop effective peptide-based vaccinations against rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE), while studies in other rheumatic diseases are still limited. Peptide-based active vaccination against pathogenic cytokines such as TNF-α and interferon-α (IFN-α) is shown to be promising in treating RA or SLE. Moreover, peptide-based tolerogenic vaccinations also have encouraging results in treating RA or SLE. However, most studies available now have been mainly based on animal models, while evidence from clinical studies is still lacking. The translation of these advances from experimental studies into clinical therapy remains impeded by some obstacles such as species difference in immunity, disease heterogeneity, and lack of safe delivery carriers or adjuvants. Nevertheless, advances in high-throughput technology, bioinformatics, and nanotechnology may help overcome these impediments and facilitate the successful development of peptide-based vaccination therapy for rheumatic diseases.

N-Butanol Extract of Gastrodia elata Suppresses Inflammatory Responses in Lipopolysaccharide-Stimulated Macrophages and Complete Freund's Adjuvant- (CFA-) Induced Arthritis Rats via Inhibition of MAPK Signaling Pathway

Gastrodia elata is a traditional herbal medicine that has been used for centuries to treat rheumatism. Previous studies have confirmed that ethanol extracts of Gastrodia elata have anti-inflammatory and antioxidant activities, and the n-butanol fraction exerts a higher inhibitory effect. However, the in vivo anti-inflammatory effects of Gastrodia elata have not been evaluated. Thus, we assessed the therapeutic effect of the n-butanol extract of Gastrodia elata (BGE) on complete Freund's adjuvant- (CFA-) induced arthritis rats which were separated into six groups (NOR; MODEL; CFA + dexamethasone (DEX); CFA + 25, 50, 100 mg/kg BGE). The paw swelling, joint radiology, and histology were used to analyze the effect of BGE on delaying the progression of rheumatoid arthritis. Furthermore, serum levels of inflammatory cytokines were analyzed via ELISA. In addition, the effect of BGE on nitric oxide (NO) production, expression of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2(COX-2), and inflammatory cytokines were detected in lipopolysaccharide- (LPS-) stimulated RAW264.7 macrophage cells. Lastly, the impacts of BGE on the activation of the mitogen-activated protein kinases (MAPK) pathway in CFA rats and LPS-stimulated RAW264.7 macrophage were examined by western blot analysis. The results show that BGE can significantly reduce paw swelling without losing the body weight of rats. Imaging assessment confirms that BGE can protect cartilage from destruction, as well as reducing inflammatory cell infiltration and synovial proliferation. Moreover, BGE suppresses the production of inflammatory cytokines in serum and inhibits the activation of the phosphorylation of p38 and ERK in CFA rats. BGE was also demonstrated to decrease the production of NO and inflammatory cytokines in LPS-stimulated RAW264.7 cells. The effect of BGE in LPS-induced expression leads to reduced p38 and ERK phosphorylation and also downregulates the protein expression of iNOS and COX-2. Taken together, BGE exhibits a potential therapeutic effect on CFA rats, and its anti-inflammatory and antioxidant effects were possibly exerted by regulation of ERK/p38MAPK.

Anti-oxidant and anti-inflammatory effects of cinnamaldehyde and eugenol on mononuclear cells of rheumatoid arthritis patients

Rheumatoid arthritis (RA) is an autoimmune disorder affecting joints and frequently characterized by initial local and later systemic inflammation. The present study was conducted with the aim to determine the anti-inflammatory and antioxidant effects of cinnamaldehyde and eugenol in the peripheral blood mononuclear cells (PBMC) of RA patients. PBMCs obtained from RA patients were treated with varying concentrations of cinnamaldehyde and eugenol. The levels of tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6) were monitored in the 24-h culture supernatant of PBMCs. Reactive oxygen species formation, biomolecular oxidation and the activities of antioxidant enzymes were also determined. FTIR analysis was done to determine structural alterations in the PBMCs. Molecular docking was performed to gain an insight into the binding mechanism of eugenol and cinnamaldehyde with pro-inflammatory cytokines. The levels of pro-inflammatory cytokines and markers of oxidative stress were found to be elevated in the PBMC culture of RA patients as compared to the healthy controls. Cinnamaldehyde and eugenol have significantly reduced the levels of cytokines. Reactive oxygen species formation, biomolecular oxidation and antioxidant defense response were also ameliorated by treating PBMCs with both the compounds. FTIR results further confirms cinnamaldehyde and eugenol mediated protection to biomolecules of PBMCs of RA patients. Molecular docking results indicates interaction of cinnamaldehyde and eugenol with key residues of TNF-α and IL-6. Cinnamaldehyde and eugenol were found to exert potent anti-inflammatory and anti-oxidant effects on the PBMC culture of RA patients. So, these compounds may be used as an adjunct in the management of RA.

A novel recombinant RANKL vaccine prepared by incorporation of an unnatural amino acid into RANKL and its preventive effect in a murine model of collagen-induced arthritis

Rheumatoid arthritis (RA) is an autoimmune disease characterized by chronic inflammatory synovitis, bone atrophy, and subsequent progressive destruction of articular tissue. Targeted inhibition of receptor activator of NF-kB ligand (RANKL) has been highly successful in preventing RA-mediated bone erosion in animal models and patients, suggesting that development of a RANKL vaccine might be of therapeutic value. Our previous study has shown that the recombinant RANKL vaccine Y²³⁴pNO₂Phe, generated by replacement of a single tyrosine residue (Tyr²³⁴) in murine RANKL (mRANKL) with p-nitrophenylalanine (pNO₂Phe), induces a high titer antibody response and prevents ovariectomy (OVX)-induced bone loss in mice. This aim of this study was to further evaluate the vaccine's preventive effects in a murine model of collagen-induced arthritis. The results of this study showed that Y²³⁴pNO₂Phe not only induced a high titer antibody response and inhibited osteoclastogenesis but also significantly prevented bone erosion and ameliorated the severity of a collagen-induced arthritis (CIA) model in mice. Moreover, use of the vaccine improved the clinical situations of the CIA mice. These results suggest a potential application of an anti-RANKL vaccine in the treatment of RA-induced bone erosion.

Trichinella spiralis Infection Mitigates Collagen-Induced Arthritis via Programmed Death 1-Mediated Immunomodulation

Helminth infection induces Th2-biased immune responses and inhibitory/regulatory pathways that minimize excessive inflammation to facilitate the chronic infection of helminth in the host and in the meantime, prevent host hypersensitivity from autoimmune or atopic diseases. However, the detailed molecular mechanisms behind modulation on inflammatory diseases are yet to be clarified. Programmed death 1 (PD-1) is one of the important inhibitory receptors involved in the balance of host immune responses during chronic infection. Here, we used the murine model to examine the role of PD-1 in CD4+ T cells in the effects of Trichinella spiralis infection on collagen-induced arthritis (CIA). Mice infected with T. spiralis demonstrated higher expression of PD-1 in the spleen CD4+ T cells than those without infection. Mice infected with T. spiralis 2 weeks prior to being immunized with type II collagen displayed lower arthritis incidence and significantly attenuated pathology of CIA compared with those of uninfected mice. The therapeutic effect of T. spiralis infection on CIA was reversed by blocking PD-1 with anti-PD-1 antibody, associated with enhanced Th1/Th17 pro-inflammatory responses and reduced Th2 responses. The role of PD-1 in regulating CD4+ T cell differentiation and proliferation during T. spiralis infection was further examined in PD-1 knockout (PD-1-/-) C57BL/6 J mice. Interestingly, T. spiralis-induced alteration of attenuated Th1 and enhanced Th2/regulatory T cell differentiation in wild-type (WT) mice was effectively diminished in PD-1-/- mice characterized by recovered Th1 cytokine levels, reduced levels of Th2 and regulatory cytokines and CD4+CD25+Foxp3+ cells. Moreover, T. spiralis-induced CD4+ T cell proliferation suppression in WT mice was partially restored in PD-1-/- mice. This study introduces the first evidence that PD-1 plays a critical role in helminth infection-attenuated CIA in a mouse model by regulating the CD4+ T cell function, which may provide the new insights into the mechanisms of helminth-induced immunomodulation of host autoimmunity.

Anhuienoside C Ameliorates Collagen-Induced Arthritis through Inhibition of MAPK and NF-κB Signaling Pathways

Anemone flaccida Fr. Schmidt (Ranunculaceae) (Di Wu in Chinese) is used to treat punch injuries and rheumatoid arthritis (RA). Our previous report has shown that crude triterpenoid saponins from Anemone flaccida exhibited anti-arthritic effects on type II collagen-induced arthritis in rats. Furthermore, anhuienoside C (AC), a saponin compound isolated from A. flaccida, was observed to suppress the nitric oxide production in lipopolysaccharide (LPS)-treated macrophage RAW 264.7 cells. In this study, we examined the effects of AC on the prevention and treatment of collagen-induced arthritis in a mouse model and evaluated the potential mechanisms involved. We observed that oral administration of AC significantly suppressed the paw swelling and arthritic score, decreased the body weight loss, and decreased the spleen index. Improvement in the disease severity was accompanied by the reduction of cluster of differentiation 68 (CD68)-positive cells in the ankle joint and inhibition of the pro-inflammatory cytokine tumor necrosis factor alpha (TNF-α) in the synovium of the joint. Mechanistic studies indicated that AC exerted its anti-inflammatory activity by inhibiting the mRNA expression levels of inducible nitric oxide synthase, cyclooxygenase-2, TNF-α, interleukin (IL)-1β, and IL-6 and by suppressing the production of inflammatory cytokines such as TNF-α, IL-1β, and IL-6 in LPS-treated RAW 264.7 cells. AC also blocked the LPS-induced activation of the extracellular signal-regulated kinase, c-Jun N-terminal kinase, and p38 mitogen-activated protein kinase pathways. Additionally, the LPS-induced activation of nuclear factor kappa-B (NF-κB) was significantly suppressed by AC treatment, as indicated by down-regulation of TLR4 and inhibition of the nuclear translocation of NF-κB p65 and by activation and degradation of the inhibitor of kappa B. These findings indicated that AC has a great potential to be developed as a therapeutic agent for human RA.

Aryl hydrocarbon receptor suppresses the osteogenesis of mesenchymal stem cells in collagen-induced arthritic mice through the inhibition of β-catenin

The contributions of aryl hydrocarbon receptor (Ahr) to the pathogenesis of rheumatoid arthritis (RA), particularly bone loss, have not been clearly explored. The imbalance between osteoblasts and osteoclasts is a major reason for bone loss. The dysfunction of osteoblasts, which are derived from mesenchymal stem cells (MSCs), induced bone erosion occurs earlier and is characterized as more insidious. Here, we showed that the nuclear expression and translocation of Ahr were both significantly increased in MSCs from collagen-induced arthritis (CIA) mice. The enhanced Ahr suppressed the mRNA levels of osteoblastic markers including Alkaline phosphatase (Alp) and Runt-related transcription factor 2 (Runx2) in the differentiation of MSCs to osteoblasts in CIA. The 2, 3, 7, 8-tetrachlorodibenzo-p-dioxin (TCDD)-mediated activation of Ahr dose-dependently suppressed the expression of osteoblastic markers. In addition, the expression of β-catenin was reduced in CIA MSCs compared with control, and the TCDD-mediated activation of the Ahr significantly inhibited β-catenin expression. The Wnt3a-induced the activation of Wnt/β-catenin pathway partly rescued the osteogenesis decline induced by TCDD. Taken together, these results indicate that activated Ahr plays a negative role in CIA MSCs osteogenesis, possibly by suppressing the expression of β-catenin.

A Truncated IL-17RC Peptide Ameliorates Synovitis and Bone Destruction of Arthritic Mice

Peptide-based therapy, such as modified peptides, has attracted increased attention. IL-17 is a promising therapeutic target for autoimmune diseases, and levels of circulating bioactive IL-17 are associated with rheumatoid arthritis severity. In this study, a modified truncated IL-17RC is generated to ameliorate inflammation and bone destruction in arthritis. The truncated IL-17RC binds to both IL-17A and IL-17F with higher binding capacity compared to nonmodified IL-17RC. In addition, the truncated IL-17RC reduces the secretion of inflammatory and osteoclastogenic factors induced by IL-17A/F in vitro. Moreover, the administration of truncated IL-17RC dramatically improves symptoms of inflammation and inhibited bone destruction in collagen-induced arthritis mice. Collectively, these data demonstrate that modified truncated IL-17RC peptide may be a more effective treatment strategy in the simultaneous inhibition of both IL-17A and IL-17F signaling, whereas the existing agents neutralize IL-17A or IL-17F alone. These suggest that the truncated IL-17RC may be a potential candidate in the treatment of inflammatory associated bone diseases.

Direct chemotherapeutic dual drug delivery through intra-articular injection for synergistic enhancement of rheumatoid arthritis treatment

The effectiveness of systemic rheumatoid arthritis (RA) treatments is limited by difficulties in achieving therapeutic doses within articular joints. We evaluated the ability of intra-articular administration of injectable formulations to synergistically enhance repair of RA joints. Methotrexate-loaded hyaluronic acid (Met-HA), dexamethasone-loaded microcapsules (Dex-M), and Dex-M dispersed inside Met-HA were prepared as viscous emulsions and injected into articular joints using a needle to form a drug depot. By near-infrared (NIR) fluorescence imaging, we confirmed the local release of NIR from the depot injected into the articular joint over an extended period. In comparison with the subjects treated with Met-HA or Dex-M alone, subjects treated simultaneously with Met-HA and Dex-M exhibited faster and more significant RA repair. Collectively, these results indicated that the drug depot formed after intra-articular injection of Met-HA/Dex-M induced long-lasting drug release and allowed Met and Dex to effectively act in the articular joint, resulting in enhanced RA repair.

Designation of a novel DKK1 multiepitope DNA vaccine and inhibition of bone loss in collagen-induced arthritic mice

Dickkopf-1 (DKK1), a secretory inhibitor of canonical Wnt signaling, plays a critical role in certain bone loss diseases. Studies have shown that serum levels of DKK1 are significantly higher in rheumatoid arthritis (RA) patients and are correlated with the severity of the disease, which indicates the possibility that bone erosion in RA may be inhibited by neutralizing the biological activity of DKK1. In this study, we selected a panel of twelve peptides using the software DNASTAR 7.1 and screened high affinity and immunogenicity epitopes in vitro and in vivo assays. Furthermore, we optimized four B cell epitopes to design a novel DKK1 multiepitope DNA vaccine and evaluated its bone protective effects in collagen-induced arthritis (CIA), a mouse model of RA. High level expression of the designed vaccine was measured in supernatant of COS7 cells. In addition, intramuscular immunization of BALB/c mice with this vaccine was also highly expressed and sufficient to induce the production of long-term IgG, which neutralized natural DKK1 in vivo. Importantly, this vaccine significantly attenuated bone erosion in CIA mice compared with positive control mice. These results provide evidence for the development of a DNA vaccine targeted against DKK1 to attenuate bone erosion.

Quantification of the effects of ionic strength, viscosity, and hydrophobicity on protein-ligand binding affinity

In order to quantify the interactions between molecules of biological interest, the determination of the dissociation constant (K d) is essential. Estimation of the binding affinity in this way is routinely performed in "favorable" conditions for macromolecules. Crucial data for ligand-protein binding elucidation is mainly derived from techniques (e.g., macromolecular crystallography) that require the addition of high concentration of salts and/or other additives. In this study we have evaluated the effect of temperature, ionic strength, viscosity, and hydrophobicity on the K d of three previously characterized protein-ligand systems, based on variation in their binding sites, in order to provide insight into how these often overlooked unconventional circumstances impact binding affinity. Our conclusions are as follows: (1) increasing solvent viscosity in general is detrimental to ligand binding, (2) moderate increases in temperature have marginal effects on the dissociation constant, and (3) the degree of hydrophobicity of the ligand and the binding site determines the extent of the influence of cosolvents and salt concentration on ligand binding affinity.

Strategies for active TNF-α vaccination in rheumatoid arthritis treatment

Local overexpression of tumor necrosis factors alpha (TNF-α) is critically involved in the inflammatory response and tissue destruction of rheumatoid arthritis (RA). Currently, the blockade of TNF-α by passive immunotherapy is indeed efficacious in the treatment of RA, but it still present some disadvantages. Induction of high level of anti-TNF-α neutralizing autoantibodies by TNF-α autovaccine has been developed to avoid these shortcomings. This review is to briefly introduce several vaccination approaches that have been used to induce a B cell response, including coupled TNF-α (entire/peptide) with a carrier protein, modified TNF-α with foreign Th cell epitopes, and engineered DNA vaccine. These methods showed remarkable therapeutic efficiency in experimental animals which indicated that active TNF-α immunization would be a promising and cost-effective new treatment option for RA.