Reduced IgG titers against pertussis in rheumatoid arthritis: Evidence for a citrulline-biased immune response and medication effects

et al. 2021

Preprint

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Lasting immunity will be critical for overcoming the coronavirus disease 2019 (COVID-19) pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). However, factors that drive the development of high titers of anti-SARS-CoV-2 antibodies and how long those antibodies persist remain unclear. Our objective was to comprehensively evaluate anti-SARS-CoV-2 antibodies in a clinically diverse COVID-19 convalescent cohort at defined time points to determine if anti-SARS-CoV-2 antibodies persist and to identify clinical and demographic factors that correlate with high titers. Using a novel multiplex assay to quantify IgG against four SARS-CoV-2 antigens, a receptor binding domain-angiotensin converting enzyme 2 inhibition assay, and a SARS-CoV-2 neutralization assay, we found that 98% of COVID-19 convalescent subjects had anti-SARS-CoV-2 antibodies five weeks after symptom resolution (n=113). Further, antibody levels did not decline three months after symptom resolution (n=79). As expected, greater disease severity, older age, male sex, obesity, and higher Charlson Comorbidity Index score correlated with increased anti-SARS-CoV-2 antibody levels. We demonstrated for the first time that COVID-19 symptoms, namely fever, abdominal pain, diarrhea and low appetite, correlated consistently with higher anti-SARS-CoV-2 antibody levels. Our results provide new insights into the development and persistence of anti-SARS-CoV-2 antibodies.

Section: Methodsmentioning

confidence: 99%

Fever, Diarrhea, and Severe Disease Correlate with High Persistent Antibody Levels against SARS-CoV-2

Amjadi

Armbrust

et al. 2021

Preprint

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“…Human subject research was carried out in compliance with the Helsinki Declaration and was approved by the University of Wisconsin Institutional Review Board. Serum from age-and sex-matched controls and RA patients were selected from the University of Wisconsin (UW) Rheumatology Biorepository as described previously (20,21). Briefly, RA patients were identified based on having ≥2 outpatient visits within 24 months at which RA-associated International Classification of Diseases codes were used (22), or 1 visit and a positive CCP test result.…”

Section: Methodsmentioning

confidence: 99%

Disordered Antigens and Epitope Overlap Between Anti–Citrullinated Protein Antibodies and Rheumatoid Factor in Rheumatoid Arthritis

Zheng

Arthritis & Rheumatology

Fahmy

et al. 2019

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Objective. Anti-citrullinated protein antibodies (ACPAs) and rheumatoid factor (RF) are commonly present in rheumatoid arthritis (RA) without a clear rationale for their coexistence. Moreover, autoantibodies develop against proteins with different posttranslational modifications and native proteins without obvious unifying characteristics of the antigens. We undertook this study to broadly evaluate autoantibody binding in seronegative and seropositive RA to identify novel features of reactivity.Methods. An array was created using a total of 172,828 native peptides, citrulline-containing peptides, and homocitrulline-containing peptides derived primarily from proteins citrullinated in the rheumatoid joint. IgG and IgM binding to peptides were compared between cyclic citrullinated peptide (CCP)-positive RF+, CCP+RF−, CCP−RF+, and CCP−RF− serum from RA patients (n = 48) and controls (n = 12). IgG-bound and endogenously citrullinated peptides were analyzed for amino acid patterns and predictors of intrinsic disorder, i.e., unstable 3-dimensional structure. Binding to IgG-derived peptides was specifically evaluated. Enzyme-linked immunosorbent assay confirmed key results.Results. Broadly, CCP+RF+ patients had high citrulline-specific IgG binding to array peptides and CCP+RF− and CCP−RF+ patients had modest citrulline-specific IgG binding (median Z scores 3.02, 1.42, and 0.75, respectively; P < 0.0001). All RA groups had low homocitrulline-specific binding. CCP+RF+ patients had moderate IgG binding to native peptides (median Z score 2.38; P < 0.0001). The highest IgG binding was to citrulline-containing peptides, irrespective of protein identity, especially if citrulline was adjacent to glycine or serine, motifs also seen in endogenous citrullination in the rheumatoid joint. Highly bound peptides had multiple features predictive of disorder. IgG from CCP+RF+ patients targeted citrulline-containing IgG-derived peptides.Conclusion. Disordered antigens, which are frequently citrullinated, and common epitopes for ACPAs and RF are potentially unifying features for RA autoantibodies.

“…The study was conducted in accordance with the Declaration of Helsinki, and the protocol was approved by the Institutional Review Board of the University of Wisconsin-Madison (#2015-0156). All clinical data and biologic samples were obtained from the University of Wisconsin (UW) Rheumatology Biorepository first described in [6,44]. Briefly, the biorepository contains data and samples from subjects at least 18 years old and medically homed at UW Health.…”

Section: Methodsmentioning

confidence: 99%

“…Corning 96 well plates were left uncoated or were coated with 10µg/mL of native or citrullinated histone, or the same concentration of PAD4 present in the citrullinated histone solution in phosphate buffered saline (PBS) overnight at 4 °C. After washing 3 times (0.1% Tween 20 in PBS), wells were incubated with block solution (5% nonfat dried milk in 0.2% Tween 20 in PBS) at room temperature for 2–4 h, then with serum (prepared as in [44]) diluted 1:200 in block solution for 2 h at room temperature. Wells were then washed 5 times, incubated with anti-human IgG-HRP diluted 1:5000 in 5% nonfat dried milk in 0.2% Tween 20 in PBS for 2 h at room temperature, washed again 5 times, and exposed to 1-Step Slow TMB-ELISA (Thermo Fisher Scientific) for 5–10 min, then stopped with 0.18 M sulfuric acid.…”

Section: Methodsmentioning

confidence: 99%

Reduced Anti-Histone Antibodies and Increased Risk of Rheumatoid Arthritis Associated with a Single Nucleotide Polymorphism in PADI4 in North Americans

Bawadekar

Nguyen

et al. 2019

IJMS

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Autoantibodies against citrullinated proteins are a hallmark of rheumatoid arthritis, a destructive inflammatory arthritis. Peptidylarginine deiminase 4 (PAD4) has been hypothesized to contribute to rheumatoid arthritis by citrullinating histones to induce neutrophil extracellular traps (NETs), which display citrullinated proteins that are targeted by autoantibodies to drive inflammation and arthritis. Consistent with this theory, PAD4-deficient mice have reduced NETs, autoantibodies, and arthritis. However, PAD4′s role in human rheumatoid arthritis is less clear. Here, we determine if single nucleotide polymorphism rs2240335 in PADI4, whose G allele is associated with reduced PAD4 in neutrophils, correlates with NETs, anti-histone antibodies, and rheumatoid arthritis susceptibility in North Americans. Control and rheumatoid arthritis subjects, divided into anti-cyclic citrullinated peptide (CCP) antibody positive and negative groups, were genotyped at rs2240335. In homozygotes, in vitro NETosis was quantified in immunofluorescent images and circulating NET and anti-histone antibody levels by enzyme linked immunosorbent assay (ELISA). Results were compared by t-test and correlation of rheumatoid arthritis diagnosis with rs2240335 by Armitage trend test. NET levels did not significantly correlate with genotype. G allele homozygotes in the CCP− rheumatoid arthritis group had reduced anti-native and anti-citrullinated histone antibodies. However, the G allele conferred increased risk for rheumatoid arthritis diagnosis, suggesting a complex role for PAD4 in human rheumatoid arthritis.