Anti-citrullinated peptides as autoantigens in rheumatoid arthritis-relevance to treatment

Correlation of Serum Vitamin D and High-Density Lipoprotein (HDL) Cholesterol Levels With Disease Activity in Rheumatoid Arthritis: A Single-Center Experience From Eastern India

Background Rheumatoid arthritis (RA) is a progressive, symmetric, and erosive polyarthritis with a variety of extraarticular manifestations such as mononeuritis multiplex, central nervous system vasculitis, Felty's syndrome, dyslipidemia, carditis, and interstitial lung disease. Vitamin D plays a role in both adaptive and innate immunity, and its deficiency leads to the development of many autoimmune disorders. Additionally, RA patients have a lipid paradox consisting particularly of dysfunctional and low levels of high-density lipoprotein (HDL) with reduced low-density lipoprotein lowering effect, which increases cardiovascular morbidity and potentiates widespread systemic inflammation. Both are modifiable risk factors. Although there are numerous studies on vitamin D and HDL cholesterol in disease progression in RA, there is sparse literature from India studying both these factors in combination. In this study, we tried to establish the correlation of serum vitamin D and HDL cholesterol levels, if any, with disease activity using the Disease Activity Score 28 Erythrocyte Sedimentation Rate (DAS28 ESR) score. Methods A descriptive cross-sectional study comprising 80 patients was conducted at a tertiary care center in Eastern India over 12 months. Newly diagnosed RA patients aged >17 years satisfying the diagnostic criteria were included. Serum vitamin D level and HDL cholesterol were measured. Then, the DAS28 ESR score was calculated, and a correlation was looked for between serum vitamin D and HDL cholesterol. Results Patients aged 35-43 years accounted for 32 (42.5%) of participants, of whom 58 (72.5%) were females. Almost half, 38 (47.5%), had vitamin D deficiency. The mean vitamin D level was 22.988 ± 10.01 ng/ml. The mean HDL cholesterol level was 42.3 ± 7.23 mg/dl. The mean DAS28-ESR score was 3.81 ± 1.19. A statistically significant inverse correlation was found between vitamin D levels and DAS28 ESR score (p -0.0003) and HDL (p -0.000349). Conclusions Vitamin D deficiency and low HDL cholesterol levels are more common in RA patients. These factors may contribute to increased disease activity. Both are treatable factors in addition to conventional therapies.

The emerging role of neutrophil extracellular traps in the progression of rheumatoid arthritis

Rheumatoid arthritis (RA) is a chronic autoimmune disease with a complex etiology. Neutrophil extracellular traps (NETs are NETwork protein structures activated by neutrophils to induce the cleavage and release of DNA-protein complexes). Current studies have shown the critical involvement of NETs in the progression of autoimmune diseases, Neutrophils mostly gather in the inflammatory sites of patients and participate in the pathogenesis of autoimmune diseases in various ways. NETs, as the activated state of neutrophils, have attracted much attention in immune diseases. Many molecules released in NETs are targeted autoantigens in autoimmune diseases, such as histones, citrulline peptides, and myeloperoxidase. All of these suggest that NETs have a direct causal relationship between the production of autoantigens and autoimmune diseases. For RA in particular, as a disorder of the innate and adaptive immune response, the pathogenesis of RA is inseparable from the generation of RA. In this article, we investigate the emerging role of NETs in the pathogenesis of RA and suggest that NETs may be an important target for the treatment of inflammatory autoimmune diseases.

Advancing autoimmune Rheumatic disease treatment: CAR-T Cell Therapies - Evidence, Safety, and future directions

INTRODUCTION

Despite advancements in managing autoimmune rheumatic diseases (ARDs) with existing treatments, many patients still encounter challenges such as inadequate responses, difficulty in maintaining remission, and side effects. Chimeric Antigen Receptor (CAR) T-cell therapy, originally developed for cancer, has now emerged as a promising option for cases of refractory ARDs.

METHODS

A search of the literature was conducted to compose a narrative review exploring the current evidence, potential safety, limitations, potential modifications, and future directions of CAR-T cells in ARDs.

RESULTS

CAR-T cell therapy has been administered to patients with refractory ARDs, including systemic lupus erythematosus, antisynthetase syndrome, and systemic sclerosis, demonstrating significant improvement. Notable responses include enhanced clinical symptoms, reduced serum autoantibody titers, and sustained remissions in disease activity. Preclinical and in vitro studies using both animal and human samples also support the efficacy and elaborate on potential mechanisms of CAR-T cells against antineutrophil cytoplasmic antibody-associated vasculitis and rheumatoid arthritis. While cautious monitoring of adverse events, such as cytokine release syndrome, is crucial, the therapy appears to be highly tolerable. Nevertheless, challenges persist, including cost, durability due to potential CAR-T cell exhaustion, and manufacturing complexities, urging the development of innovative solutions to further enhance CAR-T cell therapy accessibility in ARDs.

CONCLUSIONS

CAR-T cell therapy for refractory ARDs has demonstrated high effectiveness. While no significant warning signs are currently reported, achieving a balance between therapeutic efficacy and safety is vital in adapting CAR-T cell therapy for ARDs. Moreover, there is significant potential for technological advancements to enhance the delivery of this treatment to patients, thereby ensuring safer and more effective disease control for patients.

Cell-Based Therapy and Genome Editing as Emerging Therapeutic Approaches to Treat Rheumatoid Arthritis

Rheumatoid arthritis (RA) is an autoimmune disease characterized by chronic inflammation of the joints. Although much remains unknown about the pathogenesis of RA, there is evidence that impaired immune tolerance and the development of RA are related. And it is precisely the restoration of immune tolerance at the site of the inflammation that is the ultimate goal of the treatment of RA. Over the past few decades, significant progress has been made in the treatment of RA, with higher rates of disease remission and improved long-term outcomes. Unfortunately, despite these successes, the proportion of patients with persistent, difficult-to-treat disease remains high, and the task of improving our understanding of the basic mechanisms of disease development and developing new ways to treat RA remains relevant. This review focuses on describing new treatments for RA, including cell therapies and gene editing technologies that have shown potential in preclinical and early clinical trials. In addition, we discuss the opportunities and limitations associated with the use of these new approaches in the treatment of RA.

Immunophenotypic Landscape of synovial tissue in rheumatoid arthritis: Insights from ACPA status

Objective

To examine the clinical features and synovial pathologies in rheumatoid arthritis (RA) patients across varying titers of circulating anti-citrullinated protein antibodies (ACPA).

Methodology

We devised a negative pressure suction and rebound synovial biopsy tool to enhance the yield of synovial biopsies, noted for its ease and safety of use. This research involved a retrospective examination of 60 active RA patients who underwent synovial biopsies with this tool from June to November 2013 at our institution. A range of disease activity markers were collected, including DAS28-CRP, ESR, CRP, count of swollen and tender joints, VAS pain scale, and so forth. Synovial tissue underwent HE staining and immunohistochemistry, including synovitis grading (GSS) and counting of B cells (CD20), T cells (CD3), macrophages (CD68), and plasma cells (CD138).

Participants

were categorized into three groups as per ACPA titers: ACPA-negative (0-5U/mL), low-titer (5-20U/mL), and high-titer (above 20U/mL). The study compared the clinical features and synovial pathologies across these groups.

Results

Of the 60 RA patients, they were segregated into three groups based on ACPA titers: 20 in ACPA-negative, 9 in the low-titer group, and 31 in the high-titer group. No significant differences were observed in GSS scores, synovial cell proliferation and loss, matrix activation, inflammatory infiltration, and neovascularization among these groups (P > 0.05). The high-titer ACPA group demonstrated significantly increased counts of CD3+ T cells, CD20+ B cells, and CD68+ macrophages in synovial tissues compared to the ACPA-negative and low-titer groups (p < 0.05), along with a higher incidence of ectopic lymphoid neogenesis (p < 0.05). Ordinal logistic regression revealed that rheumatoid factor (RF), and counts of synovial T cells, B cells, macrophages, and ectopic lymphoid neogenesis correlated with ACPA titers (P < 0.05), particularly lymphoid neogenesis (OR = 3.63, P = 0.023).

Conclusion

RA patients with high-titer ACPA demonstrate elevated levels of inflammatory cell infiltration in synovial tissues, with ectopic lymphoid neogenesis showing a strong correlation with high ACPA positivity.

Genetic Polymorphisms in Exon 5 and Intron 5 and 7 of AIRE Are Associated with Rheumatoid Arthritis Risk in a Hungarian Population

BACKGROUND

Rheumatoid arthritis (RA) is chronically persistent synovitis and systemic inflammation. Although multiple contributors are detected, only one is pivotal in the neonatal period: the negative selection of autoimmune naïve T-cells by the autoimmune regulator (AIRE) transcriptional factor.

METHODS

Single-nucleotide polymorphisms (SNPs) in the DNA-binding site of AIRE may determine its function and expression. We intended to analyse site-specific allelic polymorphisms in two exon (rs878081 and rs1055311) and three intron (rs1003853, rs2075876, and rs1003854) loci with an RA risk. Our analytical case-control study analysed 270 RA patients and 322 control subjects in five different genetic models using quantitative real-time PCR (qPCR) with TaqMan® assays.

RESULTS

Statistically significant differences were found between the odds of allelic polymorphisms in the loci of rs878081, rs1003854, and rs1003853 among the controls and RA patients, and the disease activity seemed to be significantly associated with the genotypic subgroups of rs878081 and rs1055311. Our in silico analysis supported this, suggesting that allele-specific alterations in the binding affinity of transcriptional factor families might determine RA activity.

CONCLUSION

Our findings highlight the involvement of neonatal self-tolerance in RA pathogenesis, providing novel insights into disease development and paving the way for an analysis of further site-specific genetic polymorphisms in AIRE to expand the intervention time for RA.

Regulation of cytokine and chemokine expression by histone lysine methyltransferase MLL1 in rheumatoid arthritis synovial fibroblasts

Histone lysine methylation is thought to play a role in the pathogenesis of rheumatoid arthritis (RA). We previously reported aberrant expression of the gene encoding mixed-lineage leukemia 1 (MLL1), which catalyzes methylation of histone H3 lysine 4 (H3K4), in RA synovial fibroblasts (SFs). The aim of this study was to elucidate the involvement of MLL1 in the activated phenotype of RASFs. SFs were isolated from synovial tissues obtained from patients with RA or osteoarthritis (OA) during total knee joint replacement. MLL1 mRNA and protein levels were determined after stimulation with tumor necrosis factor α (TNFα). We also examined changes in trimethylation of H3K4 (H3K4me3) levels in the promoters of RA-associated genes (matrix-degrading enzymes, cytokines, and chemokines) and the mRNA levels upon small interfering RNA-mediated depletion of MLL1 in RASFs. We then determined the levels of H3K4me3 and mRNAs following treatment with the WD repeat domain 5 (WDR5)/MLL1 inhibitor MM-102. H3K4me3 levels in the gene promoters were also compared between RASFs and OASFs. After TNFα stimulation, MLL1 mRNA and protein levels were higher in RASFs than OASFs. Silencing of MLL1 significantly reduced H3K4me3 levels in the promoters of several cytokine (interleukin-6 [IL-6], IL-15) and chemokine (C-C motif chemokine ligand 2 [CCL2], CCL5, C-X-C motif chemokine ligand 9 [CXCL9], CXCL10, CXCL11, and C-X3-C motif chemokine ligand 1 [CX3CL1]) genes in RASFs. Correspondingly, the mRNA levels of these genes were significantly decreased. MM-102 significantly reduced the promoter H3K4me3 and mRNA levels of the CCL5, CXCL9, CXCL10, and CXCL11 genes in RASFs. In addition, H3K4me3 levels in the promoters of the IL-6, IL-15, CCL2, CCL5, CXCL9, CXCL10, CXCL11, and CX3CL1 genes were significantly higher in RASFs than OASFs. Our findings suggest that MLL1 regulates the expression of particular cytokines and chemokines in RASFs and is associated with the pathogenesis of RA. These results could lead to new therapies for RA.

Immunotherapy Strategy for Systemic Autoimmune Diseases: Betting on CAR-T Cells and Antibodies

Systemic autoimmune diseases (SAIDs), such as systemic lupus erythematosus (SLE), systemic sclerosis (SSc) and rheumatoid arthritis (RA), are fully related to the unregulated innate and adaptive immune systems involved in their pathogenesis. They have similar pathogenic characteristics, including the interferon signature, loss of tolerance to self-nuclear antigens, and enhanced tissue damage like necrosis and fibrosis. Glucocorticoids and immunosuppressants, which have limited specificity and are prone to tolerance, are used as the first-line therapy. A plethora of novel immunotherapies have been developed, including monoclonal and bispecific antibodies, and other biological agents to target cellular and soluble factors involved in disease pathogenesis, such as B cells, co-stimulatory molecules, cytokines or their receptors, and signaling molecules. Many of these have shown encouraging results in clinical trials. CAR-T cell therapy is considered the most promising technique for curing autoimmune diseases, with recent successes in the treatment of SLE and SSc. Here, we overview novel therapeutic approaches based on CAR-T cells and antibodies for targeting systemic autoimmune diseases.

Exploring key genes associated with neutrophil function and neutrophil extracellular traps in heart failure: a comprehensive analysis of single-cell and bulk sequencing data

Background: Heart failure (HF) is a complex and heterogeneous manifestation of multiple cardiovascular diseases that usually occurs in the advanced stages of disease progression. The role of neutrophil extracellular traps (NETs) in the pathogenesis of HF remains to be explored. Methods: Bioinformatics analysis was employed to investigate general and single-cell transcriptome sequencing data downloaded from the GEO datasets. Differentially expressed genes (DEGs) associated with NETs in HF patients and healthy controls were identified using transcriptome sequencing datasets and were subsequently subjected to functional enrichment analysis. To identify potential diagnostic biomarkers, the random forest algorithm (RF) and the least absolute shrinkage and selection operator (LASSO) were applied, followed by the construction of receiver operating characteristic (ROC) curves to assess accuracy. Additionally, single-cell transcriptome sequencing data analysis identified key immune cell subpopulations in TAC (transverse aortic constriction) mice potentially involved in NETs regulation. Cell-cell communication analysis and trajectory analysis was then performed on these key cell subpopulations. Results: We identified thirteen differentially expressed genes (DEGs) associated with NET through differential analysis of transcriptome sequencing data from HF (heart failure) samples. Utilizing the Random Forest and Lasso algorithms, along with experimental validation, we successfully pinpointed four diagnostic markers (CXCR2, FCGR3B, VNN3, and FPR2) capable of predicting HF risk. Furthermore, our analysis of intercellular communication, leveraging single-cell sequencing data, highlighted macrophages and T cells as the immune cell subpopulations with the closest interactions with neutrophils. Pseudo-trajectory analysis sheds light on the differentiation states of distinct neutrophil subpopulations. Conclusion: In this study, we conducted an in-depth investigation into the functions of neutrophil subpopulations that infiltrate cardiac tissue in TAC mice. Additionally, we identified four biomarkers (CXCR2, FCGR3B, VNN3, and FPR2) associated with NETs in HF. Our findings enhance the understanding of immunology in HF.

Cystic fibrosis autoantibody signatures associate with Staphylococcus aureus lung infection or cystic fibrosis-related diabetes

Introduction

While cystic fibrosis (CF) lung disease is characterized by persistent inflammation and infections and chronic inflammatory diseases are often accompanied by autoimmunity, autoimmune reactivity in CF has not been studied in depth.

Methods

In this work we undertook an unbiased approach to explore the systemic autoantibody repertoire in CF using autoantibody microarrays.

Results and discussion

Our results show higher levels of several new autoantibodies in the blood of people with CF (PwCF) compared to control subjects. Some of these are IgA autoantibodies targeting neutrophil components or autoantigens linked to neutrophil-mediated tissue damage in CF. We also found that people with CF with higher systemic IgM autoantibody levels have lower prevalence of S. aureus infection. On the other hand, IgM autoantibody levels in S. aureus-infected PwCF correlate with lung disease severity. Diabetic PwCF have significantly higher levels of IgA autoantibodies in their circulation compared to nondiabetic PwCF and several of their IgM autoantibodies associate with worse lung disease. In contrast, in nondiabetic PwCF blood levels of IgA autoantibodies correlate with lung disease. We have also identified other autoantibodies in CF that associate with P. aeruginosa airway infection. In summary, we have identified several new autoantibodies and associations of autoantibody signatures with specific clinical features in CF.

Different Clinical Relevance of Anti-Citrullinated Protein Antibodies in RA Patients

The objective of the study was to find a potential relationship between ACPAs and disease activity, bone destruction, and ACPA responses to various therapeutic regimens. The study included 232 patients with rheumatoid arthritis (RA); 90 patients had early RA, and 142 patients had an advanced stage of the disease. 77 (85.6%) patients with early RA were highly positive for anti-CCP, and 29 (70.7%) patients were highly positive for anti-MCV. A positive correlation was found between anti-MCV and DAS28 (r = 0.4; p = 0.04). As for advanced RA, 78 (80.4%) patients were high-positive for anti-CCP, and 70 (79.5%) were high-positive for anti-MCV. There was a positive correlation between anti-MCV concentration and SDAI (r = 0.4; p = 0.02), as well as CDAI (r = 0.4; p = 0.02). No significant correlations were found between the anti-CCP levels and activity indices, anti-CCP and acute-phase parameters in both early and advanced RA groups. Higher total Sharp scores (96.5 (65.0-122.0)) were found in pts highl-positive for anti-MCV (n = 79), compared to low-positive/negative (n = 27) patients (57.0 (31.0-88.0); p < 0.05). Anti-MCV levels dropped significantly in pts on rituximab and tocilizumab therapy at weeks 12 and 24 after initiation of treatment, while high anti-CCP concentration persisted throughout the treatment. Anti-MCV levels correlated with inflammatory activity and development of bone destruction and decreased in pts on treatment. Anti-CCP was less responsive and showed minor changes during treatment; therefore, its thorough monitoring was not feasible.

Anti-citrullinated protein antibodies as biomarkers in rheumatoid arthritis

INTRODUCTION

The serological biomarker anti-citrullinated protein antibodies (ACPAs) may have several functions but is especially important for the diagnosis of rheumatoid arthritis (RA) along with clinical symptoms.

AREAS COVERED

This review provides an overview of ACPAs, which are useful in RA diagnostics and may improve our understanding of disease etiology. PubMed was searched with combinations of words related to antibodies recognizing epitopes containing the post-translationally modified amino acid citrulline in combination with rheumatoid arthritis; cyclic citrullinated peptide, CCP, anti-CCP, anti-citrullinated protein antibodies, ACPA, citrullination, peptide/protein arginine deiminase, PAD, filaggrin, vimentin, keratin, collagen, perinuclear factor, EBNA1, EBNA2, and others. From this search, we made a qualitative extract of publications relevant to the discovery, characterization, and clinical use of these antibodies in relation to RA. We highlight significant findings and identify areas for improvement.

EXPERT OPINION

ACPAs have high diagnostic sensitivity and specificity for RA and recognize citrullinated epitopes from several proteins. The best-performing single epitope originates from Epstein-Barr Virus nuclear antigen 2 and contains a central Cit-Gly motif, which is recognized by ACPAS when located in a flexible peptide structure. In addition, ACPAs may also have prognostic value, especially in relation to early treatment, although ACPAs' main function is to aid in the diagnosis of RA.

Citrullination of actin-ligand and nuclear structural proteins, cytoskeleton reorganization and protein redistribution across cellular fractions are early events in ionomycin-induced NETosis

Neutrophil extracellular traps (NETs) are web-like structures of DNA coated with cytotoxic proteins and histones released by activated neutrophils through a process called NETosis. NETs release occurs through a sequence of highly organized events leading to chromatin expansion and rupture of nuclear and cellular membranes. In calcium ionophore-induced NETosis, the enzyme peptidylargine deiminase 4 (PAD4) mediates chromatin decondensation through histone citrullination, but the biochemical pathways involved in this process are not fully understood. Here we use live-imaging microscopy and proteomic studies of the neutrophil cellular fractions to investigate the early events in ionomycin-triggered NETosis. We found that before ionomycin-stimulated neutrophils release NETs, profound biochemical changes occur in and around their nucleus, such as, cytoskeleton reorganization, nuclear redistribution of actin-remodeling related proteins, and citrullination of actin-ligand and nuclear structural proteins. Ionomycin-stimulated neutrophils rapidly lose their characteristic polymorphic nucleus, and these changes are promptly communicated to the extracellular environment through the secretion of proteins related to immune response. Therefore, our findings revealed key biochemical mediators in the early process that subsequently culminates with nuclear and cell membranes rupture, and extracellular DNA release.

Positive Effects of Biologics on Osteoporosis in Rheumatoid Arthritis

Osteoporosis is a systemic skeletal disorder that causes vulnerability of bones to fracture owing to reduction in bone density and deterioration of the bone tissue microstructure. The prevalence of osteoporosis is higher in patients with autoimmune inflammatory rheumatic diseases, including rheumatoid arthritis (RA), than in those of the general population. In this autoimmune inflammatory rheumatic disease, in addition to known risk factors for osteoporosis, various factors such as chronic inflammation, autoantibodies, metabolic disorders, drugs, and decreased physical activity contribute to additional risk. In RA, disease-related inflammation plays an important role in local or systemic bone loss, and active treatment for inflammation can help prevent osteoporosis. In addition to conventional synthetic disease-modifying anti-rheumatic drugs that have been traditionally used for treatment of RA, biologic DMARDs and targeted synthetic DMARDs have been widely used. These agents can be employed more selectively and precisely based on disease pathogenesis. It has been reported that these drugs can inhibit bone loss by not only reducing inflammation in RA, but also by inhibiting bone resorption and promoting bone formation. In this review, the pathogenesis and research results of the increase in osteoporosis in RA are reviewed, and the effects of biological agents on osteoporosis are discussed.

Post-Translational Modifications in Tumor-Associated Antigens as a Platform for Novel Immuno-Oncology Therapies

Post-translational modifications (PTMs) are generated by adding small chemical groups to amino acid residues after the translation of proteins. Many PTMs have been reported to correlate with tumor progression, growth, and survival by modifying the normal functions of the protein in tumor cells. PTMs can also elicit humoral and cellular immune responses, making them attractive targets for cancer immunotherapy. This review will discuss how the acetylation, citrullination, and phosphorylation of proteins expressed by tumor cells render the corresponding tumor-associated antigen more antigenic and affect the immune response in multiple cancers. In addition, the role of glycosylated protein mucins in anti-cancer immunotherapy will be considered. Mucin peptides in combination with stimulating adjuvants have, in fact, been utilized to produce anti-tumor antibodies and vaccines. Finally, we will also outline the results of the clinical trial exploiting glycosylated-MUC1 as a vaccine in different cancers. Overall, PTMs in TAAs could be considered in future therapies to result in lasting anti-tumor responses.

Emerging insights of peptide-based nanotherapeutics for effective management of rheumatoid arthritis

Rheumatoid arthritis (RA) is a chronic, prevalent, immune-mediated, inflammatory, joint disorder affecting millions of people worldwide. Despite current treatment options, many patients remain unable to achieve remission and suffer from comorbidities. Because of several comorbidities as well as its chronic nature, it diminishes the quality of patients' life and intensifies socioeconomic cargo. Consolidating peptides with immensely effective drug delivery systems has the ability to alleviate adverse effects associated with conventional treatments. Peptides are widely used as targeting moieties for the delivery of nanotherapeutics. The use of novel peptide-based nanotherapeutics may open up new avenues for improving efficacy by promoting drug accumulation in inflamed joints and reducing off-target cytotoxicity. Peptide therapeutics have grabbed significant attention due to their advantages over small drug molecules as well as complex targeting moieties. In light of this, the market for peptide-based medications is growing exponentially. Peptides can provide the versatility required for the successful delivery of drugs due to their structural diversity and their capability to lead drugs at the site of inflammation while maintaining optimum therapeutic efficacy. This comprehensive review aims to provide an enhanced understanding of recent advancements in the arena of peptide-based nanotherapeutics to strengthen targeted delivery for the effective management of rheumatoid arthritis. Additionally, various peptides having therapeutic roles in rheumatoid arthritis are summarized along with regulatory considerations for peptides.

The bone-protective mechanisms of active components from TCM drugs in rheumatoid arthritis treatment

Rheumatoid arthritis (RA) is an autoimmune disease whose hallmarks are synovial inflammation and irreversible bone destruction. Bone resorption resulting from osteoclasts involves the whole immune and bone systems. Breakdown of bone remodeling is attributed to overactive immune cells that produce large quantities of cytokines, upregulated differentiation of osteoclasts with enhanced resorptive activities, suppressed differentiation of osteoblasts, invading fibroblasts and microbiota dysbiosis. Despite the mitigation of inflammation, the existing treatment in Western medicine fails to prevent bone loss during disease progression. Traditional Chinese medicine (TCM) has been used for thousands of years in RA treatment, showing great efficacy in bone preservation. The complex components from the decoctions and prescriptions exhibit various pharmacological activities. This review summarizes the research progress that has been made in terms of the bone-protective effect of some representative compounds from TCM drugs and proposes the substantial mechanisms involved in bone metabolism to provide some clues for future studies. These active components systemically suppress bone destruction via inhibiting joint inflammation, osteoclast differentiation, and fibroblast proliferation. Neutrophil, gut microenvironment and microRNA has been proposed as future focus.

Clinical Relevance of Autoantibodies and Inflammatory Parameters in Non-infectious Scleritis

PURPOSE

Scleritis is a potentially blinding disorder, with highly unpredictable course and outcome. We analyzed the prevalence and clinical relevance of autoantibodies and inflammatory parameters in non-infectious scleritis.

METHODS

Retrospective analysis of laboratory findings in all consecutive patients at the department of Ophthalmology of the Erasmus MC with non-infectious scleritis.

RESULTS

We included 81 patients with non-infectious scleritis. A systemic autoimmune disease was present in 46%. Positive anti-nuclear antibodies were found in 30%, anti-neutrophil cytoplasmic antibodies were positive in 19%, and the presence of rheumatoid factor was shown in 17%. The aforementioned autoantibodies, as well as inflammatory parameters, failed to show prognostic clinical value. In contrast, anti-citrullinated peptide antibodies (ACPA), found in 9% of scleritis patients, were significantly associated with the development of scleral necrosis (P = .01).

CONCLUSIONS

The presence of ACPA in patients with non-infectious scleritis was associated with the development of scleral necrosis.

Human abdominal aortic aneurysm (AAA): Evidence for an autoimmune antigen-driven disease

Abdominal aortic aneurism (AAA) is a complex immunological disease with a strong genetic component, and one of the ten leading causes of death of individuals 55-74 years old worldwide. Strong evidence has been accumulated suggesting that AAA is an autoimmune specific antigen-driven disease. Mononuclear cells infiltrating AAA lesions comprised of T and B lymphocytes and other cells expressing early-, intermediate- and late-activation antigens, and the presence of antigen-presenting cells have been documented, demonstrating an ongoing immune response. The three components of the trimolecular complex, T-cell receptor (TCR)/peptide (antigen)/HLA have been identified in AAA, and specifically: (i) clonal expansions of T-cell clones in AAA lesions; (ii) the association of AAA with particular HLA Class I and Class II; and (iii) self or nonself putative AAA-associated antigens. IgG autoantibodies recognizing proteins present in normal aortic tissue have been reported in patients with AAA. Molecular mimicry, defined as the sharing of antigenic epitopes between microorganisms (bacteria, viruses) and self antigens, maybe is responsible for T-cell responses and antibody production in AAA. Also, the frequency and the suppressor activity of CD4 + CD25 + FOXP3+ Tregs and the expression of FOXP3 transcripts and protein have been reported to be significantly impaired in AAA patients vs normal donors.

Periodontal Treatment for Chronic Periodontitis With Rheumatoid Arthritis

BACKGROUND

History of rheumatoid arthritis (RA) increases risk of periodontal diseases. A pro-inflammatory condition noted in periodontitis is considered a trigger for RA. Thus, periodontal treatment aimed at attenuating the pro-inflammatory state could aid in potentially reducing the risk of RA.

AIMS

The objective of this research was to assess the effect of periodontal therapy on rheumatoid factor, Disease Activity Score-28, anti-citrullinated protein antibody, and C-reactive protein levels in patients with chronic periodontitis (CP) and RA.

MATERIALS AND METHODS

The sample consisted of 28 patients with CP and RA. The study was designed to be a double-blind, randomised controlled clinical study. The samples were randomly categorised to either the treatment group (n = 13) or the control group (n = 15). CP status (plaque index, bleeding on probing, probing pocket depth, clinical attachment loss), clinical rheumatologic status (Disease Activity Score), and biochemical status (C-reactive protein, anti-citrullinated protein antibody, and rheumatoid factor) were assessed at baseline and at follow-up at 8 to 12 weeks.

RESULTS

The treatment group showed a highly statistically significant reduction in bleeding on probing (P < .005), probing pocket depth (P < .001), plaque index (P < .001), and C-reactive protein (P < .001); a gain in the clinical attachment loss (P < .001) and an improvement in Disease Activity Score-28 (P = .001) were observed at reassessment following nonsurgical periodontal treatment as compared to the control group. However, blood serum anti-citrullinated protein antibody (P = .002) and rheumatoid factor levels (P = .351) were found to increase from baseline to 8 to 12 weeks following subgingival scaling and root planing.

CONCLUSIONS

Reduction of inflammation in the periodontium by nonsurgical periodontal therapy did not reduce anti-citrullinated protein antibody and rheumatoid factor levels. However, it has shown improvement in periodontal conditions, and remarkable changes were observed in the clinical Disease Activity Score and C-reactive protein levels of individuals with RA.

Phytochemicals from medicinal plants from African forests with potentials in rheumatoid arthritis management

OBJECTIVES

Rheumatoid arthritis (RA) is a chronic systemic autoimmune disease characterized by inflammation, pain, and cartilage and bone damage. There is currently no cure for RA. It is however managed using nonsteroidal anti-inflammatory drugs, corticosteroids and disease-modifying anti-rheumatic drugs, often with severe side effects. Hidden within Africa's lush vegetation are plants with diverse medicinal properties including anti-RA potentials. This paper reviews the scientific literature for medicinal plants, growing in Africa, with reported anti-RA activities and identifies the most abundant phytochemicals deserving research attention. A search of relevant published scientific literature, using the major search engines, such as Pubmed/Medline, Scopus, Google Scholar, etc. was conducted to identify medicinal plants, growing in Africa, with anti-RA potentials.

KEY FINDINGS

Twenty plants belonging to 17 families were identified. The plants are rich in phytochemicals, predominantly quercetin, rutin, catechin, kaempferol, etc., known to affect some pathways relevant in RA initiation and progression, and therefore useful in its management.

SUMMARY

Targeted research is needed to unlock the potentials of medicinal plants by developing easy-to-use technologies for preparing medicines from them. Research attention should focus on how best to exploit the major phytochemicals identified in this review for the development of anti-RA 'green pharmaceuticals'.

Identification of a Novel Serological Marker in Seronegative Rheumatoid Arthritis Using the Peptide Library Approach

Rheumatoid arthritis (RA) is a systemic autoimmune disease characterized by chronic inflammation mainly affecting the joints leading to cartilage and bone destruction. The definition of seropositive or seronegative RA is based on the presence or absence of rheumatoid factor (RF) and anti-citrullinated peptide antibodies (ACPAs). Other autoantibodies have been identified in the last decade such as antibodies directed against carbamylated antigens, peptidyl-arginine deiminase type 4 and v-Raf murine sarcoma viral oncogene homologue B. In order to identify relevant autoantigens, we screened a random peptide library (RPL) with pooled IgGs obtained from 50 patients with seronegative RA. Patients’ sera were then used in an ELISA test to identify the most frequently recognized peptide among those obtained by screening the RPL. Sera from age- and sex-matched healthy subjects were used as controls. We identified a specific peptide (RA-peptide) recognized by RA patients’ sera, but not by healthy subjects or by patients with other immune-mediated diseases. The majority of sera from seronegative and seropositive RA patients (73.8% and 63.6% respectively) contained IgG antibodies directed against the RA-peptide. Interestingly, this peptide shares homology with some self-antigens, such as Protein-tyrosine kinase 2 beta, B cell scaffold protein, Liprin-alfa1 and Cytotoxic T lymphocyte protein 4. Affinity purified anti-RA-peptide antibodies were able to cross react with these autoantigens. In conclusion, we identified a peptide that is recognized by seropositive and, most importantly, by seronegative RA patients’ sera, but not by healthy subjects, conferring to this epitope a high degree of specificity. This peptide shares also homology with other autoantigens which can be recognized by autoantibodies present in seronegative RA sera. These newly identified autoantibodies, although present also in a percentage of seropositive RA patients, may be considered as novel serum biomarkers for seronegative RA, which lacks the presence of RF and/or ACPAs.

Effects of nonsurgical periodontal therapy in patients with rheumatoid arthritis: a prospective before and after study

Background

periodontal therapy has been suggested to have systemic effects. However, studies of periodontal therapy in rheumatoid arthritis patients have produced controversial results.

Aim

To compare the effects of nonsurgical periodontal therapy on biochemical markers of rheumatoid arthritis and periodontal parameters in patients with and without rheumatoid arthritis.

Methods

a prospective before-and-after study was conducted that included 21 participants without and 29 participants with rheumatoid arthritis. Periodontal parameters, Porphyromonas gingivalis detection, C-reactive protein, rheumatoid factor and anti-citrullinated protein antibodies were measured at baseline and three months after nonsurgical periodontal therapy and the changes were statistically assessed.

Results

In general, both groups presented statistically significant improvement in periodontal parameters (p<0.05). There was an increase in the counts of P. gingivalis in both groups at three months. In addition, there was a reduction in levels of anti-citrullinated protein antibodies and rheumatoid factor in participants with rheumatoid arthritis. In contrast, C-reactive protein levels increased in both groups but were higher in the rheumatoid arthritis group. Periodontal parameters in rheumatoid arthritis participants under disease-modifying antirheumatic drugs presented a slightly higher improvement (p <0.05).

Conclusions

Nonsurgical periodontal therapy has similar improvements in periodontal parameters in patients with and without rheumatoid arthritis. In addition, nonsurgical periodontal therapy may benefit serum levels of anti-citrullinated protein antibodies and rheumatoid factors in patients with rheumatoid arthritis. NCT04658615.

B Cell Metabolism and Autophagy in Autoimmunity

B cells are central to the pathogenesis of multiple autoimmune diseases, through antigen presentation, cytokine secretion, and the production of autoantibodies. During development and differentiation, B cells undergo drastic changes in their physiology. It is emerging that these are accompanied by equally significant shifts in metabolic phenotype, which may themselves also drive and enforce the functional properties of the cell. The dysfunction of B cells during autoimmunity is characterised by the breaching of tolerogenic checkpoints, and there is developing evidence that the metabolic state of B cells may contribute to this. Determining the metabolic phenotype of B cells in autoimmunity is an area of active study, and is important because intervention by metabolism-altering therapeutic approaches may represent an attractive treatment target.

Rheumatoid arthritis associated with the occurrence, severity and extension of periodontitis: A case-control study

Background

Emerging evidence pointed to a potential association between periodontitis (PE) and rheumatoid arthritis (RA), based on shared characteristics and similarities in risk factors, immunogenetics and pathways of tissue destruction. The aim of this study was to evaluate the potential association between RA and PE, as well as the influence of risk variables in this association.

Material and Methods

The present case-control study comprised 471 individuals (157 cases with RA and 314 controls) that underwent a full-mouth periodontal examination. The association between risk variables and the occurrence of AR and PE were evaluated through univariate and multivariate logistic analysis.

Results

Higher frequency (p<0.001), severity (p=0.006) and extension (p=0.018) of PE was observed among the cases when compared to controls. Variables retained in the final multivariate models for the occurrence of PE were: lower number of teeth, smoking, no use of dental floss, ≥4 daily toothbrushing and RA; for the occurrence of RA were: higher age, female gender, smoking, alcohol use and PE. It is important to stress that RA (OR=2.53; 95%CI 1.24-3.86; p<0.001) was retained in the model for PE, and PE (OR=3.12; 95%CI 1.47-4.26; p<0.001) was retained in the model for RA.

Conclusions

The present study demonstrated a high frequency of PE among individuals with RA and an important association among the occurrence, severity and extension of PE and RA and smoking. Key words:Case-control study, risk factors, periodontitis, rheumatoid arthritis.

Elucidating Citrullination by Mass Spectrometry and Its Role in Disease Pathogenesis

This review focuses on discussing key mechanisms in disease pathogenesis mediated by the protein post-translational modification citrullination. These processes are discussed in depth in the context of complex diseases such as rheumatoid arthritis, cancer, central nervous system disorders, and cardiovascular disease. Additionally, a critical evaluation of challenges in laboratory detection of citrullination sites is also outlined. In this context, the role of mass spectrometry is discussed with a focus on contemporary techniques that offer promising options to detect the exact site of protein citrullination. Novel methods described in the paper have the potential to detect and quantify the occurrence of post-translational modification sites for diagnosis and therapeutic purposes with a high degree of specificity and sensitivity. Furthermore, they offer a much faster performance than traditional techniques making them ideal for large-scale experimentation.

The possible role of oral microbiome in autoimmunity

OBJECTIVE

The human microbiome refers to the entire habitat, including microorganisms, their genomes and the surrounding environmental conditions of the microbial ecosystem. When the equilibrium between microbial habitats and host is disturbed, dysbiosis is caused. The oral microbiome (OMB) has been implicated in the manifestation of many intra- and extraoral diseases. Lately, there has been an intense effort to investigate and specify the relationship between microbial complexes, especially that of the oral cavity and intestine and autoimmunity. This study aimed to review the current literature about the possible role of the OMB in the pathogenesis of autoimmune diseases.

METHODS

We searched for published articles in English indexed in PubMed, Medline, Research Gate and Google Scholar using a search strategy that included terms for oral microbiome, autoimmune diseases, dysbiosis and next-generation sequencing.

RESULTS

An important number of articles were gathered and used for the description of the possible impact of dysbiosis of OMB in the pathogenesis of Sjögren's syndrome, systemic lupus erythematosus, rheumatoid arthritis, Behcet's disease, Crohn's disease and psoriasis.

CONCLUSION

This review article draws attention to the relationship between OMB and the triggering of a number of autoimmune diseases. Although this specific topic has been previously reviewed, herein, the authors review recent literature regarding the full list of nosological entities related to the OMB, point out the interaction between the microbiome and sex hormones with regard to their role in autoimmunity and discuss novel and promising therapeutic approaches for systemic autoimmune diseases. Furthermore, the question arises of whether the OMB is associated with oral bullous autoimmune diseases.

Clinical and microbiological effects of non-surgical periodontal treatment in individuals with rheumatoid arthritis: a controlled clinical trial

The effect of periodontal treatment on clinical, microbiological and serological parameters of patients with rheumatoid arthritis (RA) are scarce and controversial. The aim of this study was to investigate the influence of non-surgical periodontal treatment on clinical periodontal status, subgingival bacterial levels of Aggregatibacter actinomycetemcomitans, Porphyromonas gingivalis, Tannerella forsythia, Treponema denticola and RA activity through a controlled clinical trial on individuals with RA and periodontitis (PE). From a convenience sample, 107 individuals were considered eligible and consecutively allocated in four groups: (1) individuals without PE and RA (- PE-RA, n = 30); (2) individuals without PE and with RA (- PE + RA, n = 23); (3) individuals with PE and RA (+ PE + RA, n = 24); and (4) individuals with PE and without RA (+ PE-RA, n = 30). Full-mouth periodontal clinical examinations, microbiological analysis and Disease Activity Score (DAS-28) evaluations were performed at baseline (T1) and 45 days after non-surgical periodontal treatment (T2). At T1, individuals + PE + RA showed greater severity of PE than + PE-RA individuals. At T2, significant reductions were observed in all periodontal clinical parameters in both groups (p < 0.001) with a significant reduction in DAS-28 in + PE + RA (p = 0.011). Individuals + PE-RA and + PE-RA showed significant reductions for all bacteria (p < 0.001). Additionally, P. gingivalis demonstrated an expressively significant reduction in + PE + RA (p < 0.001). Non-surgical periodontal treatment was effective on improving the clinical periodontal condition, improving the RA clinical status and reducing the presence of periodontal pathogens. Brazilian Registry of Clinical Trials (ReBEC) protocol #RBR-8g2bc8 ( https://www.ensaiosclinicos.gov.br/rg/RBR-8g2bc8/ ).

In vitro elimination of autoreactive B cells from rheumatoid arthritis patients by universal chimeric antigen receptor T cells

OBJECTIVES

Autoreactive B cells play a crucial role in the pathogenesis of rheumatoid arthritis (RA), and B cell-depleting therapies using an antibodies, such as rituximab, have been suggested to be effective in RA treatment. However, transient B cell depletion with rituximab is associated with significant safety challenges related to global suppression of the immune system and thus increases the risks of infection and cancer development. To address selective and persistent issues associated with RA therapy, we developed a customised therapeutic strategy employing universal antifluorescein isothiocyanate (FITC) chimeric antigen receptor T cells (CAR-T cells) combined with FITC-labelled antigenic peptide epitopes to eliminate autoreactive B cell subsets recognising these antigens in RA.

METHODS

For a proof-of-concept study, four citrullinated peptide epitopes derived from citrullinated autoantigens, namely, citrullinated vimentin, citrullinated type II collagen, citrullinated fibrinogen and tenascin-C, and a cyclocitrulline peptide-1 were selected as ligands for targeting autoreactive B cells; Engineered T cells expressing a fixed anti-FITC CAR were constructed and applied as a universal CAR-T cell system to specifically eliminate these protein-specific autoreactive B cells via recognition of the aforementioned FITC-labelled autoantigenic peptide epitopes.

RESULTS

We demonstrated that anti-FITC CAR-T cells could be specifically redirected and kill hybridoma cells generated by immunisation with antigenic peptides, and autoreactive B cell subsets from RA patients via recognition of corresponding FITC-labelled citrullinated peptide epitopes. Additionally, the cytotoxicity of the CAR-T cells was dependent on the presence of the peptides and occurred in a dose-dependent manner.

CONCLUSIONS

The approach described here provides a direction for precise, customised approaches to treat RA and can likely be applied to other systemic autoimmune diseases.

Increased IgA anti-citrullinated protein antibodies in the periodontal inflammatory exudate of healthy individuals compared to rheumatoid arthritis patients

Aim

To assess rheumatoid arthritis (RA)‐associated autoantibodies in the gingivocrevicular fluid (GCF) of RA patients and healthy controls with or without periodontal disease, as chronic mucosal inflammation in periodontal disease is hypothesized to contribute to the formation of these autoantibodies.

Materials and methods

Anti‐citrullinated protein antibodies (ACPA), rheumatoid factor (RF), and their IgA isotypes were assessed in the serum and GCF of RA patients (n = 72) and healthy controls (HC, n = 151). The presence and levels of these antibodies were studied in relation to interleukin (IL)‐8 and periodontal disease.

Results

In contrast to the HC, the levels of ACPA and RF in the serum and GCF of the RA patients were strongly correlated (p < .0001). The HC with high levels of IgA‐ACPA (n = 27) also had significantly higher levels of total IgG, total IgA, and IL‐8 in the GCF than the HC with low levels of IgA‐ACPA in the GCF (n = 124). Periodontal inflammation and smoking were seen more frequently in the group with high levels of IgA‐ACPA compared to the group with low IgA‐ACPA.

Conclusion

The IgA‐ACPA in the GCF of HC may be associated with periodontal inflammation and smoking, and could be involved in the progression to RA.

Post-translational modifications such as citrullination are excellent targets for cancer therapy

Under conditions of cellular stress, proteins can be post-translationally modified causing them to be recognized by the immune system. One such stress-induced post-translational modification (siPTM) is citrullination, the conversion of arginine residues to citrulline by peptidylarginine deiminase (PAD) enzymes. PAD enzymes are activated by millimolar concentrations of calcium which can occur during apoptosis, leading to precipitation of proteins, their subsequent uptake by B cells and stimulation of antibody responses. Detection of anti-citrullinated protein antibodies (ACPAs) is a diagnostic of rheumatoid arthritis (RA), where immune complexes stimulate inflammation around the joints. More recently, autophagy has been shown to play a role in the presentation of citrullinated peptides on MHC class II molecules to CD4⁺ helper T cells, suggesting that citrullination may be a way of alerting immune cells to cellular stress. Additionally, inflammation-induced IFNγ and concomitant MHC class II expression on target cells contributes to immune activation. Stressful conditions in the tumor microenvironment induce autophagy in cancer cells as a pro-survival mechanism. Cancer cells also over express PAD enzymes and in light of this the hypothesis that citrullinated peptides stimulate CD4⁺ T cell responses that would recognize these siPTM's produced during autophagy has been investigated. The induction of potent citrullinated peptide-specific CD4 responses has been shown in both humans and HLA transgenic mouse models. Responses in mouse models resulted in potent anti-tumour responses against tumours expressing either constitutive or IFNγ-inducible MHC class II. The anti-tumour effect relied upon direct recognition of tumours by specific CD4 T cells suggesting that citrullinated peptides are attractive targets for cancer vaccines.

Safety, tolerability, pharmacokinetics, and pharmacodynamics of PF-06650833, a selective interleukin-1 receptor-associated kinase 4 (IRAK4) inhibitor, in single and multiple ascending dose randomized phase 1 studies in healthy subjects

Background

PF-06650833 is a potent, selective inhibitor of interleukin-1 receptor-associated kinase 4 (IRAK4). Two randomized, double-blind, sponsor-open phase 1 studies evaluated the safety, pharmacokinetics, and pharmacodynamics of single (SAD) and multiple ascending doses (MAD) of PF-06650833 immediate-release (IR) and modified-release (MR) oral formulations in healthy adult subjects.

Methods

Study 1 (NCT02224651) was a 96-day, placebo-substitution, SAD study of once-daily (QD) oral PF-06650833 IR 1 to 6000 mg and MR 30 to 300 mg in fasted and fed states. Study 2 (NCT02485769) was a 14-day, placebo-controlled, MAD study of PF-06650833 IR 25 to 750 mg twice daily, IR 1000 mg four times per day, IR 330 mg three times per day, and MR 300 mg QD.

Results

PF-06650833 was generally well tolerated, with no dose-limiting treatment-emergent adverse events (TEAEs) identified in either study. TEAEs were generally mild in severity, with headache, gastrointestinal disorders, and acne most commonly reported. No serious AEs or deaths were reported. A maximum tolerated dose was not established in either study. In the SAD study, food intake delayed absorption of IR 30 mg and increased total exposure by 33%. Delayed absorption was achieved with the MR formulation (T_max of 1 h versus 8 h for IR 100 mg and MR 100 mg formulations, respectively). Food had no effect on total exposure for MR 30 mg, but reduced half-life 1.8-fold and increased C_max by 62%. In the MAD study, accumulation ranged from 0.9-fold to 1.4-fold for AUC_tau and 0.9-fold to 1.3-fold for C_max. Less than 1% of the dose was recovered unchanged in urine for all dose groups, with renal clearance ranging from 14 to 23 mL/min for IR < 750 mg and MR 300 mg. There was a sustained decrease in serum high-sensitivity C-reactive protein for IR ≥ 250 mg and MR 300 mg. Based on the cholesterol/hydroxycholesterol ratio, no apparent CYP3A induction or inhibition was observed.

Conclusions

PF-06650833, the first IRAK4 inhibitor to enter clinical development, has a favorable safety and pharmacokinetic profile and has shown evidence of pharmacological effect. The data support continued evaluation in human clinical trials for the treatment of rheumatic and autoimmune diseases.

Trial registration

Clinicaltrials.gov, NCT02224651, registered 25 August 2014; NCT02485769, registered 30 June 2015

The TNFA -857C/T Polymorphism: Association with Rheumatoid Arthritis and Anti-CCP Levels in a Mexican Population

Rheumatoid arthritis (RA) is a chronic inflammatory disease whose association with SNPs has led to the identification of biomarkers in different populations. To determine the association of the -857C/T SNP of the TNFA gene with RA and clinical parameters, 233 RA patients and 237 healthy controls were included in this study. The -857C/T polymorphism was determined using the TaqMan® system and clinical features were also determined. We found that the -857C/T SNP was in Hardy-Weinberg equilibrium. Our results showed no association of the -857C/T SNP with RA; however, RA patients carrying the TT genotype showed lower anti-CCP levels than other groups. Therefore, the TT genotype could be a risk factor for developing anti-CCP-negative RA. Our results suggest that the T allele of the TNFA -857C/T SNP exerts an influence on anti-CCP levels and could be a candidate marker for anti-CCP-negative RA.

JAK inhibitors for the treatment of autoimmune and inflammatory diseases

Cytokines play a central role in the pathophysiology of autoimmune and inflammatory diseases. Several cytokines signal through the JAK-STAT pathway, which is now recognized as a major target to inhibit the effect of a wide array of cytokines. JAK inhibitors are increasingly used in the setting of inflammatory and autoimmune diseases. While the currently approved drugs are panJAK inhibitors, more selective small molecules are being developed and tested in various rheumatic disorders. In this extensive review, we present evidence- or hypothesis-based perspectives for these drugs in various rheumatologic conditions, such as rheumatoid arthritis, systemic lupus erythematosus, giant cell arteritis, and autoinflammatory diseases.

Multiple hit infection and autoimmunity: the dysbiotic microbiota-ACPA connection in rheumatoid arthritis

PURPOSE OF REVIEW

This review highlights the most recent data obtained in this field and provides clues toward the better understanding of the close interplay between microbiota and host, leading to autoimmune diseases.

RECENT FINDINGS

A well-described model of microbiota/host interaction of relevance to autoimmunity is linking anti-citrullinated peptide antibody positive rheumatoid arthritis and alterations of microbiota largely concentrating on Porphyromonas gingivalis and more recently of Aggregatibacter actinomycetemcomitans and Prevotella copri.

SUMMARY

The perception of the classical link between microbial infection and development of autoimmune disease has evolved to the more recent concept of the connection between the microbiome/dysbiosis and breaking of immunological tolerance.

Posttranslational modifications and proteinopathies: how guardians of the proteome are defeated

Protein folding is one of the fundamental processes in life and therefore needs to be tightly regulated. Many cellular quality control systems are in place to ensure that proteostasis is optimally adjusted for a changing environment, facilitating protein folding, translocation and degradation. These systems include the molecular chaperones and the major protein degradation systems, namely the ubiquitin proteasome system and autophagy. However, the capacity of the quality control systems can be exhausted and protein misfolding and aggregation, including the formation of amyloids, can occur as a result of ageing, mutations or exogenous influences. There are many known diseases in which protein misfolding and aggregation can be the underlying cause of the pathological condition; these are referred to as proteinopathies. Over the last decade, it has become clear that posttranslational modifications can govern and modulate protein folding, and that aberrant posttranslational modifications can cause or contribute to proteinopathies. This review provides an overview of protein folding and misfolding and the role of the major protein quality control systems. It focusses on different posttranslational modifications and gives examples of how these posttranslational modifications can alter protein folding and cause or accompany proteinopathies.

Targeted metabolomics for serum amino acids and acylcarnitines in patients with lung cancer

Lung cancer is one of the most prevalent types of cancer, but accurate diagnosis remains a challenge. The aim of the present study was to create a model using amino acids and acylcarnitines for lung cancer screening. Serum samples were obtained from two groups of patients with lung cancer recruited in 2015 (including 40 patients and 100 matched controls) and 2017 (including 17 patients and 30 matched controls). Using a metabolomics method, 21 metabolites (13 types of amino acids and 8 types of acylcarnitines) were measured using liquid chromatography-tandem mass spectrometry. Data (from the 2015 and 2017 data sets) were analysed using a Mann-Whitney U test, Student's t-test, Welch's F test, receiver-operator characteristic curve or logistic regression in order to investigate the potential biomarkers. Six metabolites (glycine, valine, methionine, citrulline, arginine and C16-carnitine) were indicated to be involved in distinguishing patients with lung cancer from healthy controls. The six discriminating metabolites from the 2017 data set were further analysed using Partial least squares-discriminant analysis (PLS-DA). The PLS-DA model was verified using Spearman's correlation analysis and receiver operating characteristic curve analysis. These results demonstrated that the PLS-DA model using the six metabolites (glycine, valine, methionine, citrulline, arginine and C16-carnitine) had a strong ability to identify lung cancer. Therefore, the PLS-DA model using glycine, valine, methionine, citrulline, arginine and C16-carnitine may become a novel screening tool in patients with lung cancer.

Economic Evaluation of Anticyclic Citrullinated Peptide Positivity in Rheumatoid Arthritis

BACKGROUND

Anticyclic citrullinated peptide (anti-CCP) positivity may be a strong predictor of joint erosion and a potential biomarker for guiding treatment decisions for rheumatoid arthritis (RA). However, limited studies are currently available on the effect of anti-CCP positivity on health care utilization and/or medical costs of RA patients.

OBJECTIVE

To investigate short-term and long-term direct health care expenditures associated with anti-CCP positivity in newly diagnosed RA patients.

METHODS

A retrospective cohort study was conducted in adult RA patients within a U.S. integrated health care delivery system (January 1, 2007-June 30, 2015). Patients were required to have 2 RA diagnoses and treatment with a conventional or biologic disease-modifying antirheumatic drug (DMARD) within 12 months. The first RA diagnosis date was labeled as the index date, and patients were followed until they left the health plan, died, or reached the end of the study period. Patient demographics, anti-CCP results, comorbid conditions, and health care resource utilization during baseline (12 months before the index date) and follow-up periods were collected. Nationally recognized direct medical costs were assigned to health care utilization to calculate health care costs in 2015 U.S. dollars. The baseline differences between anti-CCP positivity and negativity and differences in censoring during follow-up were addressed using propensity scores. The mean differences in costs were estimated using recycled prediction methods.

RESULTS

2,448 newly diagnosed RA patients were identified and followed for a median of 3.7 years (range = 1-8 years). At baseline, 65.8% of patients were anti-CCP positive. Anti-CCP-positive patients had fewer comorbid conditions at baseline. During the first 12 months of follow-up, median (interquartile range) total health care expenditures for anti-CCP-positive and anti-CCP-negative patients were $6,200 ($3,563-$13,260) and $7,022 ($3,885-$12,995), respectively. After adjusting for baseline differences, total incremental mean cost associated with anti-CCP positivity during the first 12 months was estimated to be $2,163 per patient (P = 0.001). The annual incremental costs in anti-CCP-positive patients became progressively larger over time, from $2,163 during the first year to $5,062 during the fourth year. Anti-CCP positivity was associated with higher prescription, laboratory testing, and rheumatologist utilization. A higher percentage of anti-CCP-positive patients received 1 or more biologic DMARDs (11.6% for anti-CCP-positive vs. 5.7% for anti-CCP negative; P < 0.001) compared with anti-CCP-negative patients during the 12-month follow-up, which resulted in $2,499 in incremental prescription costs (P < 0.001). Total additional burden associated with anti-CCP positivity during the first 4 years was estimated to be $14,089 per patient.

CONCLUSIONS

In newly diagnosed RA patients, higher economic burden associated with anti-CCP positivity was mainly driven by prescription costs.

DISCLOSURES

This research and manuscript were funded by Bristol-Myers Squibb (BMS). Alemao and Connolly are employees and shareholders of BMS and participated in the design of the study, interpretation of the data, review/revision of the manuscript, and approval of the final version of the manuscript. An and Cheetham received a grant from BMS for this research. At the time of this study, An was employed by Western University of Health Sciences, and Cheetham was employed by Kaiser Permanente Southern California. Bider-Canfield, Kang, and Lin have nothing to disclose. Some study results were presented as a poster at the American College of Rheumatology Annual Meeting; November 5, 2017; San Diego, CA, and at the International Society for Pharmacoeconomics and Outcomes Research Meeting; May 19, 2018; Baltimore, MD.

Laboratory Assessment of Patients with Suspected Rheumatic Musculoskeletal Diseases: Challenges and Pitfalls

Current patient care in rheumatology relies primarily on a combination of traditional clinical assessment and standard laboratory tests. Investigators seek to discover new biomarkers and novel technologies to boost the research in this field. Mechanistic biomarkers such as cytokines, cell types, antibodies, signaling molecules, are rooted in the mechanism underlying the disease and can guide the clinical management of the disease. Conversely, descriptive biomarkers are byproducts of the disease process, depict the state of a disease but are not involved in its pathogenesis. In this article, we reviewed the field of common laboratory biomarkers in rheumatology, highlighting both their descriptive or mechanistic value as well as their role in clinical practice.

T cell repertoire to citrullinated self-peptides in healthy humans is not confined to the HLA-DR SE alleles; Targeting of citrullinated self-peptides presented by HLA-DP4 for tumour therapy

Post-translational modifications are induced in stressed cells which cause them to be recognised by the system. One such modification is citrullination where the positive charged arginine is modified to a neutral citrulline. We demonstrate most healthy donors show an oligoclonal CD4 response in vitro to at least one citrullinated vimentin or enolase peptide. Unlike rheumatoid arthritis patients, these T cell responses were not restricted by HLA-DRB1 shared epitope (SE) alleles, suggesting they could be presented by other MHC class II alleles. As HLA-DP is less polymorphic than HLA-DR, we investigated whether the common allele, HLA-DP4 could present citrullinated epitopes. The modification of arginine to citrulline enhanced binding of the peptides to HLA-DP4 and induced high-frequency CD4 responses in HLA-DP4 transgenic mouse models. Our previous studies have shown that tumours present citrullinated peptides restricted through HLA-DR4 which are good targets for anti-tumour immunity. In this study, we show that citrullinated vimentin and enolase peptides also induced strong anti-tumour immunity (100% survival, p < 0.0001) against established B16 tumours and against the LLC/2 lung cancer model (p = 0.034) both expressing HLA-DP4. Since most tumours do not constitutively express MHC class II molecules, models were engineered that expressed MHC class II under the control of an IFNγ inducible promoter. Immunisation with citrullinated peptides resulted in 90% survival (p < 0.001) against established B16 HHD tumour expressing IFNγ inducible DP4. These studies show that citrullinated peptides can be presented by a range of MHC class II molecules, including for the first time HLA-DP4, and are strong targets for anti-tumour immunity.

Peptidyl arginine deiminase inhibition suppresses arthritis via decreased protein citrullination in joints and serum with the downregulation of interleukin-6

Objective: To explore the relevance of citrullinated proteins and anti-citrullinated protein antibodies (ACPA) via protein arginine deiminase (PAD) inhibition in peptide glucose-6-phosphate isomerase-induced arthritis (pGIA).Methods: Cl-amidine, a PAD inhibitor, was injected into pGIA. Clinical scores and histopathological findings of ankle joints were assessed. Serum ACPA titers were analyzed using ELISA. Citrullinated protein expression in joints and sera were examined with immunohistochemistry and Western blot analysis, respectively. Serum levels of IL-6, TNFα, and IL-1β were measured with cytometric bead array (CBA). Gene expression levels of IL-6 and TNFα in joints, lymph nodes, and spleens were analyzed with quantitative PCR. GPI-specific productions of IFNγ and IL-17 from T cells in lymph nodes were evaluated.Results: Cl-amidine treatment significantly reduced arthritis severity while ACPA titers tended to be lower, but not significantly different compared to the control. Citrullinated proteins in joints and sera from treated mice were clearly decreased. With Cl-amidine treatment, serum IL-6 levels were significantly decreased, and IL-6 and TNFα gene expression were significantly reduced in joints. IL-17 production from GPI-specific T cells tended to be lower in Cl-amidine-treated mice, but not significantly different.Conclusion: Our results suggested that PAD-mediated citrullinated protein was involved in the pathogenesis of arthritis via IL-6.

Regulatory B cells: New players in inflammatory and autoimmune rheumatic diseases

OBJECTIVE

Regulatory B cells (Bregs) are a new subset of B cells with immunoregulatory functions, mainly through IL-10 production. Bregs suppress inflammatory Th1 and Th17 differentiation and induce Tregs suppressing autoimmune diseases. The aim of the study was to review the literature related to Bregs in autoimmune rheumatic diseases (ARDs).

METHODS

A literature review of publications in PUBMED published in English was performed using the relevant combinations of terms.

RESULTS

All relevant publications are discussed. Overall, recent studies in rheumatic diseases found Bregs to be decreased in ANCA-associated vasculitides (AAV) and in systemic sclerosis (SSc), particularly in SSc-associated lung fibrosis. In AAV Bregs levels are negatively correlated with autoantibody levels whereas in SSc this association is less clear but there is an inverse association with Th1 and Th17 cells. In rheumatoid arthritis (RA), Bregs were decreased, particularly in RA-associated lung fibrosis. In psoriatic arthritis IL-10 + Bregs are decreased and inversely associated with Th1 and Th17 cells. In systemic lupus erythematosus (SLE), the role of Bregs is unclear. In experimental diseases, when Bregs were expanded ex-vivo, they ameliorated established disease.

CONCLUSION

Bregs appear to be a new player in the pathogenesis of ARDs, and may offer a new strategy for therapeutic intervention.

Anti-LL37 Antibodies Are Present in Psoriatic Arthritis (PsA) Patients: New Biomarkers in PsA

Psoriatic arthritis (PsA) is a chronic inflammatory arthritis associated with psoriasis. A third of psoriatic patients develop PsA via unknown mechanisms. No reliable diagnostic markers are available for PsA, or prognostic biomarkers for PsA development in psoriasis. We previously uncovered a pro-inflammatory role for cathelicidin LL37 in lesional psoriasis skin. LL37 binds nucleic acids and stimulates plasmacytoid/myeloid dendritic cells (pDC, mDCs) to secrete type I interferon (IFN-I) and pro-inflammatory factors. LL37 becomes an autoantigen for psoriatic Th1-Th17/CD8 T cells. Anti-LL37 antibodies were detected in systemic lupus erythematosus, an autoimmune disease characterized by neutrophil-extracellular-traps release (NETosis) in target organs. LL37 can be substrate of irreversible post-translational modifications, citrullination or carbamylation, linked to neutrophil activity. Here we analyzed inflammatory factors, included LL37, in PsA and psoriasis plasma and PsA synovial fluids (SF)/biopsies. We show that LL37 (as a product of infiltrating neutrophils) and autoantibodies to LL37 are elevated in PsA, but not OA SF. Anti-LL37 antibodies correlate with clinical inflammatory markers. Anti-carbamylated/citrullinated-LL37 antibodies are present in PsA SF/plasma and, at lower extent, in psoriasis plasma, but not in controls. Plasma anti-carbamylated-LL37 antibodies correlate with PsA (DAS44) but not psoriasis (PASI) disease activity. Ectopic lymphoid structures, and deposition of immunoglobulin-(Ig)G-complexes (IC) co-localizing with infiltrating neutrophils, are observed in PsA and not OA synovial tissues (ST). Activated complement (C5a, C9), GM-CSF and IFN-I are up-regulated in PsA and not OA synovia and in PsA and psoriasis plasma but not in HD. C9 and GM-CSF levels in PsA SF correlate with clinical inflammatory markers and DAS44 (C9) and with anti-carbamylated/citrullinated-LL37 antibodies (GM-CSF and IFN-I). Thus, we uncover a role for LL37 as a novel PsA autoantibody target and correlation studies suggest participation of anti-LL37 antibodies to PsA pathogenesis. Notably, plasma antibodies to carbamylated-LL37, which correlate with DAS44, suggest their use as new disease activity markers. GM-CSF and complement C5a and C9 elevation may be responsible for autoantigens release by neutrophils and their modification, fueling inflammation and autoreactivity establishment. Finally, targeting GM-CSF, C5a, C9 can be beneficial in PsA.

Curcumin for the Management of Periodontitis and Early ACPA-Positive Rheumatoid Arthritis: Killing Two Birds with One Stone

We propose curcumin as a preventive measure to avoid/manage periodontitis (PD), and as a natural immunosuppressant for rheumatoid arthritis (RA). PD, mainly caused by Porphyromonas gingivalis forming biofilm and leading to tooth decay, is a major public health issue and a risk factor for the development of RA in humans. P. gingivalis is able to trigger experimental autoimmune arthritis in animal models and in humans can induce citrullinated peptides, which not only are a source of anti-citrullinated antibodies (ACPAs), but also participate in autoreactive responses and disease development. Curcumin appears to have efficient anti-bacterial activity against P. gingivalis infection and biofilm formation. In addition to antibacterial, anti-oxidant, and anti-inflammatory action, curcumin exerts unique immunosuppressant properties via the inhibition of Th17 pro-inflammatory responses and promotion of regulatory T cells, thus suppressing autoimmunity. We introduce curcumin as a natural product for the management of both PD and RA-related autoreactivity, possibly also as a preventive measure in early RA or individuals at high risk to develop RA.

Identification of novel biomarker as citrullinated inter-alpha-trypsin inhibitor heavy chain 4, specifically increased in sera with experimental and rheumatoid arthritis

Background

Anticitrullinated protein antibodies (ACPA) and citrullinated proteins play key roles in the pathogenesis of rheumatoid arthritis (RA). Many candidate citrullinated antigens have been identified in joints, but citrullinated proteins in sera are mostly uncertain in patients with RA. We explored the expression of citrullinated proteins in joints and sera of experimental arthritis, and we further investigated their specific expression correlated with the disease activity in patients with RA.

Methods

Citrullinated protein expression in tissues was examined by IHC in peptide glucose-6-phosphate isomerase-induced arthritis (pGIA). Serum citrullinated proteins from pGIA were examined by Western blotting, and the sequence was identified by MS. With the same methods, serum citrullinated proteins were analyzed in patients with RA, primary Sjögren’s syndrome, systemic lupus erythematosus, and osteoarthritis as well as in healthy subjects, by Western blotting and MS. In patients with RA, the relationship between the expression of the identified protein (inter-alpha-trypsin inhibitor heavy chain 4 [ITIH4]) and clinical features was evaluated, and the levels of citrullinated ITIH4 were compared before and after biological treatment. The antibody response against citrullinated ITIH4 peptide was measured by enzyme-linked immunosorbent assay.

Results

Citrullinated proteins were detected specifically in arthritic joints and sera from pGIA relative to controls. In sera, a common band of citrullinated protein at 120 kDa was revealed, and it fluctuated in parallel with arthritis score of pGIA by Western blotting. Interestingly, in 82% of RA patient sera, similar bands of citrullinated protein were specifically detected. These proteins were identified as citrullinated ITIH4, and especially the R438 site was commonly citrullinated between mice and humans. Citrullinated ITIH4 levels were associated with clinical parameters such as C-reactive protein (CRP), rheumatoid factor, and Disease Activity Score in 28 joints as measured by CRP in patients with RA. Its levels were decreased in correlation with the reduction of disease activity score after effective treatment in patients with RA. Moreover, antibody response to citrullinated epitope in ITIH4 was specifically observed in patients with RA.

Conclusions

Our results suggest that serum citrullinated ITIH4 was specifically increased in patients with RA and could be a novel biomarker for assessing disease activity in patients with RA.

Electronic supplementary material

The online version of this article (10.1186/s13075-018-1562-7) contains supplementary material, which is available to authorized users.

The Role of Flavonoids in Inhibiting Th17 Responses in Inflammatory Arthritis

Flavonoids have been considered powerful anti-inflammatory agents, and their exact immunomodulatory action as therapeutic agents in autoimmune diseases has started to emerge. Their role in the manipulation of immunoregulation is less understood. Several studies attempted to investigate the role of various flavonoids mainly in experimental models of autoimmune diseases, especially in the context of their potential effect on the increase of regulatory T cells (Tregs) and their ability to stimulate an overexpression of anti-inflammatory cytokines, in particular that of IL-10. The emergence of IL-17, a cytokine largely produced by Th17 cells, as a powerful proinflammatory stimulus which attenuates the induction of Tregs has prompted a series of studies investigating the role of flavonoids on Th17 cells in experimental models as well as human autoimmune diseases. This review thoroughly discusses accumulated data on the role of flavonoids on Th17 in rheumatoid arthritis and experimental autoimmune arthritis.

L161982 alleviates collagen-induced arthritis in mice by increasing Treg cells and down-regulating Interleukin-17 and monocyte-chemoattractant protein-1 levels

BACKGROUND

To investigate the effects and potential mechanism of L161982 (a kind of EP4 antagonist) on the collagen-induced arthritis (CIA) mice model.

METHODS

The CIA mice model were first established by immunizing with Chicken Type II Collagen on DBA/1 mice. The CIA groups were administered once a day for 2 weeks with either 5 mg/kg L161982 by intraperitoneal injections (IP), 200 U celecoxib by intragastrical injections, or 100 μl PBS (IP). At the end of the study, total arthritis score and histopathologic examination were assessed to determine CIA severity. The plasma and tissue expressions of IL-17 and monocyte chemoattractant protein-1 (MCP-1) were detected by enzyme-linked immunosorbent assay (ELISA) and Immunohistochemical staining (IHC) respectively; The number of CD4⁺CD25⁺Foxp3⁺ regulatory T cells (Treg) determined as a proportion of total CD4⁺ cells in the lymph nodes and spleen. We also tested the proliferation of isolated Tregs and the ratio of Th17 polarization of Naïve T cells under the treatment of L161982 by BrdU assay and flow cytometry respectively.

RESULTS

CIA mice treated with L161982 showed reduced arthritis scores, joint swellings, cracked cartilage surface, and less hyperplasia in the connective tissue of the articular cavity. Plasma and tissue IL-17 and MCP-1 decreased, while the proportion of Treg cells is increased both in the spleen and lymph nodes of CIA mice. Otherwise, L161982 have no direct effect on Tregs proliferation; a decreased tendency of Th17 polarization in vitro were observed in L161982-treated naïve T cells.

CONCLUSION

Although less effective than Celecoxib, L161982 also resulted in a reduction of ankle joint inflammation in CIA mice. L161982 reduces the RA severity in CIA mice through inhibition of IL-17 and MCP-1, increasing Treg cells, and reducing inflammation. The mechanism of the reduction of IL-17 in plasma or tissue after administration of L161982 might be potentially derived from the suppression of CD4⁺ T cells differentiation into Th-17 cells.