How RA Associated HLA-DR Molecules Contribute to the Development of Antibodies to Citrullinated Proteins: The Hapten Carrier Model.

The risk to develop ACPA positive rheumatoid arthritis (RA), the most destructive type of autoimmune arthritis, is carried by HLA-DRB1 alleles containing a 5 amino acid motif: the shared epitope (SE). RA is preceded by the emergence of disease specific anti citrullinated protein antibodies (ACPA). SE positive HLA-DRB1 alleles are associated with ACPA and ACPA positive RA, not with ACPA negative RA, suggesting that ACPA contribute to the pathogenesis of RA. Understanding how HLA-DRB1 genotypes influence ACPA could lead to a curative or preventive treatment of RA. The "Shared epitope binds citrullinated peptides " hypothesis suggests that RA associated HLA-DR alleles present citrullinated peptides to T cells that help ACPA producing B cells. The "Hapten carrier model" suggests that PAD4 is the target of the T cells which help ACPA specific B cells through a hapten carrier mechanism in which PAD4 is the carrier and citrullinated peptides are the haptens. Direct binding assay of citrullinated peptides to purified HLA-DR molecules does not support the "shared epitope binds citrullinated peptides" hypothesis. The Odds Ratios to develop ACPA positive RA associated with each of 12 common HLA-DRB1 genotypes match the probability that the two HLA-DR molecules they encode can bind at least one peptide from PAD4, not from citrullinated fibrinogen. Thus, PAD4 tolerization might stop the carrier effect and switch off production of ACPA.

Correlations between autoantibodies and the ATR-FTIR spectra of sera from rheumatoid arthritis patients.

Rheumatoid arthritis (RA) is one of the most common autoimmune diseases worldwide. Due to high heterogeneity in disease manifestation, accurate and fast diagnosis of RA is difficult. This study analyzed the potential relationship between the infrared (IR) spectra obtained by attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) and the presence of autoantibodies and antibodies against urease in sera. Additionally, the wave number of the IR spectrum that enabled the best differentiation between patients and healthy blood donors was investigated. Using a mathematical model involving principal component analysis and discriminant analysis, it was shown that the presence of anti-citrullinated protein antibody, rheumatoid factor, anti-neutrophil cytoplasmic antibodies, and anti-nuclear antibodies correlated significantly with the wave numbers in the IR spectra of the tested sera. The most interesting findings derived from determination of the best predictors for distinguishing RA. Characteristic features included an increased reaction with urease mimicking peptides and a correspondence with particular nucleic acid bands. Taken together, the results demonstrated the potential application of ATR-FTIR in the study of RA and identified potential novel markers of the disease.

Assessment of genetic polymorphisms within nuclear factor-κB signaling pathway genes in rheumatoid arthritis: Evidence for replication and genetic interaction.

OBJECTIVE: This study was performed to replicate the associations of genetic polymorphisms within nuclear factor-κB (NF-κB) signaling pathway genes with rheumatoid arthritis (RA), and to further examine genetic interactions in a Chinese population. METHODS: A total of eleven single-nucleotide polymorphisms (SNPs) were genotyped in 594 RA patients and 604 healthy controls. RESULTS: Genetic association analysis revealed that NFKBIE rs2233434, TNIP1 rs10036748 and BLK rs13277113 were significantly associated with RA, cyclic citrullinated peptide (CCP)-positive RA and rheumatoid factor (RF)-positive RA, and TNFAIP3 rs2230926 was significantly associated with CCP-positive RA. Significant additive interaction was observed between NFKB1 rs28362491 and IKBKE rs12142086 (RERI = 0.76, 95% CI 0.13-1.38; AP = 0.57, 95% CI 0.11-1.03), NFKBIE rs2233434 and BLK rs13277113 (RERI = 1.41, 95% CI 0.88-1.94; AP = 0.85, 95% CI 0.50-1.20), NFKBIL rs2071592 and TNIP1 rs10036748 (RERI = 0.59, 95% CI 0.17-1.02; AP = 0.46, 95% CI 0.05-0.87), UBE2L3 rs5754217 and TNFSF4 rs2205960 (RERI = 0.50, 95% CI 0.16-0.84; AP = 0.57, 95% CI 0.09-1.05). Significant multiplicative interaction was detected between BLK rs13277113 and UBE2L3 rs5754217 (p = 0.02), BLK rs13277113 and TNFSF4 rs2205960 (p = 0.03). CONCLUSIONS: Our results lent further support to the role of NF-κB signaling pathway in the pathogenesis of RA from a genetic perspective.

Citrullinated Antigens with Multiple Citrulline Similar Motif in the Diagnosis of Rheumatoid Arthritis: A Preliminary Single-Center Study.

The presence of anti-citrullinated protein antibodies (ACPAs) in the serum is one of the immunological features of rheumatoid arthritis (RA). Anti-cyclic citrullinated peptide (CCP) assay has been widely used in clinic for the diagnosis of RA. However, up to 40% of RA patients are anti-CCP negative and the diagnostic sensitivity in this population needs to be improved for better clinical management. In this study, peptides with Multiple Citrulline Similar Motif (MCSM) were synthesized and a new ELISA system, which we called RA_CP, was developed to detect citrullinated antigens with MCSM present in the serum. 106 RA,48 other arthritis patients and 41 sex- and age-matched healthy controls (HCs) were included in this study. Patients with RA have a significantly higher amount of citrullinated antigens with MCSM than other arthritis patients and HCs. RA patients with positive anti-CCP are also MCSM positive, whereas 75% anti-CCP negative patients are positive for MCSM. The diagnostic sensitivity for anti-CCP and MCSM was 81.1% and 95.3%, while the specificity was 100% and 94.4%, respectively. ROC curve analyses showed that the area under the curve (AUC) values were 0.906 (95% CI: 0.860-0.951) for anti-CCP and 0.948 (95% CI: 0.912-0.985) for MCSM while the combination of MCSM and anti-CCP test has the highest AUC (0.971, 95% CI: 0.946-0.996). Our results suggest that detection of citrullinated antigens with MCSM has improved sensitivity compared with anti-CCP assay and could serve as a biomarker in diagnosis of RA patients.

Unique autoantibody prevalence in long-term recovered SARS-CoV-2-infected individuals.

The variability in resolution of SARS-CoV-2-infections between individuals neither is comprehended, nor are the long-term immunological consequences. To assess the long-term impact of a SARS-CoV-2-infection on the immune system, we conducted a prospective study of 80 acute and former SARS-CoV-2 infected individuals and 39 unexposed donors to evaluate autoantibody responses and immune composition. Autoantibody levels against cyclic citrullinated peptide (CCP), a specific predictor for rheumatoid arthritis (RA), were significantly (p = 0.035) elevated in convalescents only, whereas both acute COVID-19 patients and long-term convalescents showed critically increased levels of anti-tissue transglutaminase (TG), a specific predictor of celiac disease (CD) (p = 0.002). Both, anti-CCP and anti-TG antibody levels were still detectable after 4-8 months post infection. Anti-TG antibodies occurred predominantly in aged patients in a context of a post-SARS-CoV-2-specific immune composition (R2 = 0.31; p = 0.044). This study shows that increased anti-CCP and anti-TG autoantibody levels can remain long-term after recovering even from mildly experienced COVID-19. The inter-relationship of the lung as viral entry side and RA- and CD-associated autoimmunity indicates that a SARS-CoV-2-infection could be a relevant environmental factor in their pathogenesis.

Pathogenic Role of Circulating Citrullinated Antigens and Anti-Cyclic Monoclonal Citrullinated Peptide Antibodies in Rheumatoid Arthritis.

We examined whether it is possible to directly detect citrullinated antigens in the serum of rheumatoid arthritis (RA) patients using a monoclonal antibody (mAb) designed to be specific for citrullinated peptides. In order to confirm the potential of the mAb as a direct arthritis-inducing substance through experimental model of RA, a monoclonal antibody (mAb) 12G1 was generated using by immunization of mice with a challenging cyclic citrullinated peptide. Immunohistochemical analysis of RA-affected synovial tissue showed that our mAb 12G1 could indeed detect citrullinated proteins in target tissues. Subsequently, serum levels of citrullinated type II collagen and filaggrin were measured in healthy volunteers, patients with RA, ankylosing spondylitis (AS), and systemic lupus erythematosus (SLE) using a 12G1-based sandwich ELISA. This showed that citrullinated filaggrin showed 78.9% sensitivity and 85.9% specificity for RA diagnosis with a cutoff optical density (OD) value of 1.013, comparable with the results from a second-generation anti-citrullinated protein antibody (ACPA) test. Circulating citrullinated collagen and filaggrin were detected even in sera of RA patients who were negative for both rheumatoid factor (RF) and ACPA. ELISA results also showed that RF and ACPA titers showed significantly positive correlation with both citrullinated collagen and filaggrin OD values in sera of RA patients. 12G1 challenging aggravated the severity of murine arthritis. In summary, mAb 12G1 can directly detect citrullinated proteins in RA target tissue and in sera of RA patients and 12G1 showed direct arthritogenic potential in vivo. This, 12G1 might be useful for diagnosis of RA including seronegative RA and may help to elucidate the pathophysiological role of citrullination in RA.

A Comprehensive Evaluation of the Relationship Between Different IgG and IgA Anti-Modified Protein Autoantibodies in Rheumatoid Arthritis.

Seropositive rheumatoid arthritis (RA) is characterized by the presence of rheumatoid factor (RF) and anti-citrullinated protein autoantibodies (ACPA) with different fine-specificities. Yet, other serum anti-modified protein autoantibodies (AMPA), e.g. anti-carbamylated (Carb), -acetylated (KAc), and malondialdehyde acetaldehyde (MAA) modified protein antibodies, have been described. In this comprehensive study, we analyze 30 different IgG and IgA AMPA reactivities to Cit, Carb, KAc, and MAA antigens detected by ELISA and autoantigen arrays in N=1985 newly diagnosed RA patients. Association with patient characteristics such as smoking and disease activity were explored. Carb and KAc reactivities by different assays were primarily seen in patients also positive for anti-citrulline reactivity. Modified vimentin (mod-Vim) peptides were used for direct comparison of different AMPA reactivities, revealing that IgA AMPA recognizing mod-Vim was mainly detected in subsets of patients with high IgG anti-Cit-Vim levels and a history of smoking. IgG reactivity to acetylation was mainly detected in a subset of patients with Cit and Carb reactivity. Anti-acetylated histone reactivity was RA-specific and associated with high anti-CCP2 IgG levels, multiple ACPA fine-specificities, and smoking status. This reactivity was also found to be present in CCP2+ RA-risk individuals without arthritis. Our data further demonstrate that IgG autoreactivity to MAA was increased in RA compared to controls with highest levels in CCP2+ RA, but was not RA-specific, and showed low correlation with other AMPA. Anti-MAA was instead associated with disease activity and was not significantly increased in CCP2+ individuals at risk of RA. Notably, RA patients could be subdivided into four different subsets based on their AMPA IgG and IgA reactivity profiles. Our serology results were complemented by screening of monoclonal antibodies derived from single B cells from RA patients for the same antigens as the RA cohort. Certain CCP2+ clones had Carb or Carb+KAc+ multireactivity, while such reactivities were not found in CCP2- clones. We conclude that autoantibodies exhibiting different patterns of ACPA fine-specificities as well as Carb and KAc reactivity are present in RA and may be derived from multireactive B-cell clones. Carb and KAc could be considered reactivities within the "Cit-umbrella" similar to ACPA fine-specificities, while MAA reactivity is distinctly different.

Increased disease activity in early arthritis patients with anti-carbamylated protein antibodies.

The initial management of rheumatoid arthritis (RA) has a high impact on disease prognosis. Therefore, we need to select the most appropriate treatment as soon as possible. This goal requires biomarkers of disease severity and prognosis. One such biomarker may be the presence of anti-carbamylated protein antibodies (ACarPA) because it is associated with adverse long term outcomes as radiographic damage and mortality. Here, we have assessed the ACarPA as short-term prognostic biomarkers. The study was conducted in 978 prospective early arthritis (EA) patients that were followed for two years. Our results show the association of ACarPA with increased levels of all the disease activity measures in the first visit after arthritis onset. However, the associations were more significant with the high levels in local measures of inflammation and physician assessment than with the increases in systemic inflammation and patient-reported outcomes. More notably, disease activity was persistently increased in the ACarPA positive patients during the two years of follow-up. These differences were significant even after accounting for the presence of other RA autoantibodies. Therefore, the ACarPA could be considered short-term prognostic biomarkers of increased disease activity in the EA patients.

Low levels of anti-cyclic citrullinated peptide (CCP) 3.1 associated with diseases other than rheumatoid arthritis.

ABSTRACT: Our aim was to investigate the newest generation anti-cyclic citrullinated peptide (CCP) antibody 3.1 assay in diagnosing rheumatoid arthritis (RA) compared with other autoimmune and non-autoimmune diseases. We performed a retrospective observational chart review of patients with a positive CCP level over a one-year period at a single academic institution and assessed the associated diagnoses after at least six-months of follow-up. Of the 281 CCP positive patients during that period, 48% had a diagnosis of RA. The positive predictive value of RA in patients with a high CCP 3.1 assay was 0.619 compared to 0.248 with a low positive CCP 3.1 assay (P < .0001). Overall, there was a lower than expected positive predictive value of CCP 3.1 level with an RA diagnosis, though the likelihood of having an RA diagnosis was higher with a higher CCP level.

Diagnostic value of anti-citrullinated α-enolase peptide 1 antibody in patients with rheumatoid arthritis: A systematic review and meta-analysis.

AIM: To evaluate the diagnostic value of anti-citrullinated α-enolase peptide 1 (anti-CEP 1) antibody in patients with rheumatoid arthritis (RA) by conducting a systematic review and meta-analysis. METHODS: The PubMed, Web of Science, Embase, Scopus, and Cochrane Library databases were searched for relevant studies published until September 23, 2020. A bivariate mixed-effects model was used to calculate the diagnostic indices from primary data of eligible studies. We performed meta-regression and subgroup analysis to explore the sources of heterogeneity. RESULTS: Twenty-four articles, with a total of 17 380 patients with RA and 7505 control participants, met the criteria for inclusion in the meta-analysis. The pooled sensitivity, specificity, and positive and negative likelihood ratios for the anti-CEP 1 antibody were 44% (95% CI: 38%-51%), 97% (95% CI: 96%-98%), and 14.81 (95% CI: 10.66-20.57) and 0.57 (95% CI: 0.52-0.64), respectively. The pooled positive and negative predictive values were 0.96 (95% CI: 0.95-0.97) and 0.53 (95% CI: 0.43-0.63), respectively. The area under the summary receiver operating characteristic curve was 0.86. Meta-regression indicated that the anti-CEP 1 antibody detection method may be a source of heterogeneity. The subgroup analysis of the group in which the anti-CEP 1 antibody was detected by using a commercial enzyme-linked immunosorbent assay (ELISA) kit had a sensitivity of 59% (95% CI: 50%-68%) and a specificity of 93% (95% CI: 85%-97%). CONCLUSIONS: The anti-CEP 1 antibody had moderate RA diagnostic value with relatively low sensitivity and high specificity. An ELISA may increase the RA diagnostic sensitivity.

Prevalence and significance of serum 14-3-3η in juvenile idiopathic arthritis.

BACKGROUND: Prompt diagnosis of juvenile idiopathic arthritis (JIA) is important to avoid long term complications. Elevated serum 14-3-3η levels improve the diagnostic sensitivity of rheumatoid factor (RF) and cyclic citrullinated peptide (CCP) antibody in adult rheumatoid arthritis (RA), and have been associated with more severe phenotype. We investigated the prevalence and clinical significance of serum 14-3-3η in different types of JIA. METHODS: JIA patients (n = 151) followed by the Pediatric Rheumatology Core at Children's Hospital of Los Angeles were categorized into 5 groups: polyarticular JIA RF+ (PJIA RF+; n = 39), PJIA RF- (n = 39), psoriatic arthritis (PsA; n = 19), enthesitis-related arthritis (ERA; n = 18), and oligoarticular JIA (OJIA [control group]; n = 36). RF, CCP antibody, and 14-3-3η were measured for all patients. 14-3-3η serum levels > 0.2 ng/mL were considered positive. Disease activity was assessed by the Juvenile Arthritis Disease Activity Score-71 (JADAS-71). RESULTS: Elevated 14-3-3η levels were detected in 34/151 (23%) patients, and across all groups tested. Most patients with 14-3-3η had titers ≥4 times above the cutoff value. The majority (22, 65%) of 14-3-3η-positive patients were also positive for RF or CCP antibodies, 16 (47%) were positive for all 3, and 12 (35%) were single-positive for 14-3-3η. The highest prevalence of 14-3-3η was in PJIA RF+ patients (49%), followed by OJIA (22%). Positivity for 14-3-3η was not significantly associated with disease activity or age at diagnosis. CONCLUSION: Serum 14-3-3η can be detected in all forms of JIA tested but appears to be most common in PJIA RF+. 14-3-3η does not appear to correlate with disease activity in JIA.

Antibodies to malondialdehyde-acetaldehyde modified low-density lipoprotein in patients with newly diagnosed inflammatory joint disease.

Objective:To assess antibodies to malondialdehyde-acetaldehyde-modified low-density lipoprotein (MAA-LDL) in patients with newly diagnosed inflammatory joint disease.Method: Patients with rheumatoid arthritis (RA), spondyloarthritis (SpA), and undifferentiated arthritis (UA), participating in the Northern Savo 2010 Study, were evaluated for metabolic syndrome (MetS), metabolic and inflammatory markers, antibodies to MAA-LDL, Aggregatibacter actinomycetemcomitans, and Porphyromonas gingivalis.Results: Among 135 newly diagnosed untreated patients, of whom 53 (39%) were diagnosed to have RA, 44 (33%) SpA, and 38 (28%) UA, 49%, 30%, and 47%, respectively, had MetS. After adjusting for age and gender, anti-MAA-LDL immunoglobulin (Ig)A (p = 0.009), IgG (p = 0.031), and IgM (p = 0.001) levels differed between the diagnostic categories, but not in patients with MetS present or absent. All antibody classes to MAA-LDL correlated with erythrocyte sedimentation rate (ESR), and IgA and IgG antibodies with high-sensitivity C-reactive protein (hs-CRP). IgA antibodies to MAA-LDL correlated with rheumatoid factor (RF), anti-citrullinated protein antibodies (ACPAs), fasting plasma glucose, IgA antibodies to A. actinomycetemcomitans, and in IgA and IgG antibodies to P. gingivalis.Conclusion: Among various arthritis groups, antibodies to MAA-LDL were most common in RA. Antibodies to modified lipoproteins were associated with inflammation measured by ESR and hs-CRP. IgA antibodies to MAA-LDL correlated with age, antibodies to periodontal bacteria, RF, ACPA, and fasting glucose. Associations between antibodies to MAA-LDL and antibodies to periodontal bacteria, RA-associated antibodies, inflammatory parameters, and plasma glucose already reflect cardiovascular burden in inflammatory joint diseases at diagnosis.

Do RA associated HLA-DR molecules bind citrullinated peptides or peptides from PAD4 to help the development of RA specific antibodies to citrullinated proteins?

PURPOSE: Rheumatoid arthritis (RA) is associated with HLA-DRB1 genes encoding a five amino acid basic motive, the shared epitope SE). Each HLA-DRB1 genotype defines a genotype specific risk of developing RA. RA is preceded by the emergence of anti citrullinated protein antibodies (ACPAs). Citrullin is a neutral version of arginin, a basic amino acid, formed after post translational modification by Peptidyl Arginyl Deiminases (PADs). HLA-DRB1 genes associated with RA are also associated with ACPAs. Two models might explain this association. Here we tested both models for prediction of HLA-DRB1 genotypic risks of developing RA. METHODS: We calculated the likelihoods for the 2 HLA-DR molecules encoded by 12 common HLA-DRB1 genotypes to bind at least one randomly chosen peptide from PAD4 or fibrinogen(native or citrullinatd) and compared them with the 12 respective HLA-DRB1genotypic risks of developing RA. RESULTS: HLA-DRB1 Genotypic risks of developing RA correlate with likelihoods of binding PAD4 peptides, not citrullinated Fibrinogen peptides. Thus, the molecular basis for the association of HLA-DR and ACPA positive RA is most likely the capability for RA associated HLA-DR molecules to bind peptides(s) from PAD4.

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.

Prevalence of anti-cyclic citrullinated peptide antibodies in patients with spondyloarthritis: A retrospective study.

OBJECTIVES: Anti-cyclic citrullinated peptide (CCP) antibodies are frequently detected in the sera of patients with rheumatoid arthritis (RA). However, recent studies have revealed a potentially high prevalence rate of these antibodies in patients with other rheumatic disorders, causing confusion while diagnosing RA. Therefore, this study aimed to evaluate the positive rate of anti-CCP antibodies in other chronic arthritis diseases focusing on patients with spondyloarthritis (SpA). METHODS: A total of 109 patients who were diagnosed with SpA at Yukioka Hospital from 1993 to 2018 were included in this retrospective analysis, including patients with ankylosing spondylitis (AS); psoriatic arthritis (PsA); synovitis, acne, pustulosis, hyperostosis, and osteitis syndrome (SAPHO); undifferentiated spondyloarthritis (uSpA); reactive arthritis (ReA); and inflammatory bowel disease-associated SpA (IBD). RESULTS: Overall, 15.3% (16/109) of patients with SpA were positive for anti-CCP antibodies, including 2.3% (1/43) in AS, 23.1% (3/13) in SAPHO, 35.0% (7/20) in PsA, 14.8% (4/27) in uSpA, 0% (0/3) in ReA, and 33.3% (1/3) in IBD. CONCLUSION: PsA patients have a significantly higher prevalence rate of positive anti-CCP antibodies among SpA patients, and the positive rates in SAPHO and uSpA were also high. These findings provide insight into the heterogeneity of SpA with relevance for RA differential diagnosis.

Cyclic Peptide Mimotopes for the Detection of Serum Anti-ATIC Autoantibody Biomarker in Hepato-Cellular Carcinoma.

Tumor-associated (TA) autoantibodies have been identified at the early tumor stage before developing clinical symptoms, which holds hope for early cancer diagnosis. We identified a TA autoantibody from HBx-transgenic (HBx-tg) hepatocellular carcinoma (HCC) model mouse, characterized its target antigen, and examined its relationship to human HCC. The mimotopes corresponding to the antigenic epitope of TA autoantibody were screened from a random cyclic peptide library and used for the detection of serum TA autoantibody. The target antigen of the TA autoantibody was identified as an oncogenic bi-functional purine biosynthesis protein, ATIC. It was upregulated in liver cancer tissues of HBx-tg mouse as well as human HCC tissues. Over-expressed ATIC was also secreted extracellularly via the cancer-derived exosomes, which might cause auto-immune responses. The cyclic peptide mimotope with a high affinity to anti-ATIC autoantibody, CLPSWFHRC, distinguishes between serum samples from HCC patients and healthy subjects with 70.83% sensitivity, 90.68% specificity (AUC = 0.87). However, the recombinant human ATIC protein showed a low affinity to anti-ATIC autoantibody, which may be incompatible as a capture antigen for serum TA autoantibody. This study indicates that anti-ATIC autoantibody can be a potential HCC-associated serum biomarker and suggests that autoantibody biomarker's efficiency can be improved by using antigenic mimicry to native antigens present in vivo.

Improved classification of rheumatoid arthritis with a score including anti-acetylated ornithine antibodies.

The presence of rheumatoid factor (RF) or anti-cyclic citrullinated peptide (anti-CCP) autoantibodies contributes to the current rheumatoid arthritis (RA) classification criteria. These criteria involve stratification on antibody levels, which limits reproducibility, and underperform in the RA patients without RF and anti-CCP. Here, we have explored if two anti-acetylated peptide antibodies (AAPA), anti-acetylated lysine (AcLys) and anti-acetylated ornithine (AcOrn), could improve the performance of the current criteria. The analysis was done in 1062 prospectively-followed early arthritis (EA) patients. The anti-AcOrn were more informative than the anti-AcLys, the conventional RA antibodies and the anti-carbamylated protein antibodies. The anti-AcOrn produced a classification that did not require antibody levels and showed improved specificity (77.6% vs. 72.6%, p = 0.003) and accuracy (79.0% vs. 75.8%, p = 0.002) over the current criteria. These improvements were obtained with a scoring system that values concordance between anti-AcOrn, RF and anti-CCP. No significant gain was obtained in sensitivity (80.2% vs. 78.8%, p = 0.25) or in improving the classification of the RA patients lacking RF and anti-CCP, although the anti-AcOrn ranked first among the analysed new antibodies. Therefore, the anti-AcOrn antibodies could contribute to the improvement of RA classification criteria by exploiting antibody concordance.

A retrospective analysis of the relationship between anti-cyclic citrullinated peptide antibody and the effectiveness of abatacept in rheumatoid arthritis patients.

This study aimed to evaluate the effectiveness of abatacept (ABA) by anti-cyclic citrullinated peptide (ACPA) status on disease activity as well as radiographic progression in patients with rheumatoid arthritis (RA) in clinical settings. A retrospective cohort study was conducted using data from a multicenter registry. Data from a total of 553 consecutive RA patients treated with intravenous ABA were included. We primarily compared the status of disease activity (SDAI) and radiographic progression (van der Heijde modified total Sharp score: mTSS) between the ACPA-negative (N = 107) and ACPA-positive (N = 446) groups. 'ACPA positive' was defined as ≥ 13.5 U/mL of anti-CCP antibody. Baseline characteristics between groups were similar. The proportion of patients who achieved low disease activity (LDA; SDAI ≤ 11) at 52 weeks was significantly higher in the ACPA-positive group. Multivariate logistic regression analysis identified ACPA positivity as an independent predictor for achievement of LDA at 52 weeks. Drug retention rate at 52 weeks estimated by the Kaplan-Meier curve was significantly higher in the ACPA-positive group. Achievement rate of structural remission (ΔmTSS ≤ 0.5) at 52 weeks was similar between groups. ABA treatment demonstrated a significantly higher clinical response and higher drug retention rate in ACPA-positive patients. Progression of joint destruction was similar between the ACPA-negative and ACPA-positive groups. Close attention should be paid to joint destruction even in patients showing a favorable response to ABA, especially when the ACPA status is positive.

Factors Influencing the Immunogenicity and Immunotoxicity of Cyclic RGD Peptide-Modified Nanodrug Delivery Systems.

c(RGDyK)-modified liposomes have been shown to be immunogenic and potentially trigger acute systemic anaphylaxis upon repeated intravenous injection in both BALB/c nude mice and ICR mice. However, questions concerning the potential influence of mouse strains, immunization routes, drug carrier properties, and changes in c(RGDyK) itself on the immunogenicity and resultant immunotoxicity (anaphylaxis) of cyclic RGD peptide-modified nanodrug delivery systems remain unanswered. Here, these potential impact factors were investigated, aiming to better understand the immunological properties of cyclic RGD peptide-based nanodrug delivery systems and seek for solutions for this immunogenicity-associated issue. It was revealed that anaphylaxis caused by intravenous c(RGDyK)-modified drug delivery systems might be avoided by altering the preimmunization route (i.e., subcutaneous injection), introducing positively charged lipids into the liposomes and by using micelles or red blood cell membrane (RBC)-based drug delivery systems as the carrier. Different murine models showed different incidences of anaphylaxis following intravenous c(RGDyK)-liposome stimulation: anaphylaxis was not observed in both SD rats and BALB/c mice and was less frequent in C57BL/6 mice than that in ICR mice. In addition, enlarging the peptide ring of c(RGDyK) by introducing amino sequence serine-glycine-serine reduced the incidence of anaphylaxis post the repeated intravenous c(RGDyKSGS)-liposome stimulation. However, immunogenicity of cyclic RGD-modified drug carriers could not be reversed, although some reduction in IgG antibody production was observed when ICR mice were intravenously stimulated with c(RGDyK)-modified micelles, RBC membrane-based drug delivery systems and c(RGDyKSGS)-liposomes instead of c(RGDyK)-liposomes. This study provides a valuable reference for future application of cyclic RGD peptide-modified drug delivery systems.

Anti-Cyclic Citrullinated Peptide Antibody as a Predictor of Rheumathoid Arthritis Complications.

INTRODUCTION: Rheumatoid arthritis (RA) is a chronic systemic autoimmune disease, with more frequent occurrence in the female gender, it primarily affects the lining of the synovial joints, and is associated with lower quality of life, inability to work, progressive disability, and all of these patients are more likely to develop other comorbidities. AIM: To display the role of anti-cyclic citrullinated peptide antibody (anti-CCP) in evaluating RA complications during a one-year follow-up, and compare its values with values of rheumatoid factor (RF). METHODS: The study included 40 patients with RA, out of which 6 were excluded during the 1-year follow-up. All patients were treated with anti-rheumatics, methothrexate 15-25mg, occasionally corticosteroids at the same doses. RESULTS: Anti-CCP values were also significantly higher during the second examination and were 5.0 ± 1.9 (range 0.5-7.6) compared to the first examination when they were 4.2 ± 1.3 (range 0.4-6.2) indicating a higher sensitivity of Anti-CCP in detecting of disease progression (t = -2.064; p = 0.043). Anti-CCP values were statistically significant in patients with complications compared to those without during the first examination and at follow-up after one year (t = 5,382; p = 0.0001). CONCLUSION: The positivity of anti-CCP antibodies is a useful marker in terms of predicting the course and prognosis of the RA. A higher titer of anti-CCP antibodies represents a poorer prognosis for the disease. Determination of the presence of anti-CCP antibodies should be performed as a routine examination in all patients with suspected rheumatoid arthritis.