Anticarbamylated protein antibodies are associated with long-term disability and increased disease activity in patients with early inflammatory arthritis:Results from the Norfolk Arthritis Register

Objectives: Anticarbamylated protein (anti-CarP) antibodies are a novel family of autoantibodies recently identified in patients with inflammatory arthritis. The aim of this study was to investigate their association with long-term outcomes of disability and disease activity over 20 years’ follow-up in a cohort of patients with inflammatory polyarthritis (IP).  Methods: Norfolk Arthritis Register recruited adults with recent-onset swelling of ≥2 joints for ≥4 weeks from 1990 to 2009. At baseline, Health Assessment Questionnaire (HAQ) and 28 joint disease activity scores (DAS28) were obtained, and C reactive protein, rheumatoid factor (RF), anticitrullinated protein antibodies (ACPA) and anti-CarP antibodies were measured. Further HAQ scores and DAS28 were obtained at regular intervals over 20 years. Generalised estimating equations were used to test the association between anti-CarP antibody status and longitudinal HAQ and DAS28 scores; adjusting for age, gender, smoking status, year of inclusion and ACPA status. Analyses were repeated in subgroups stratified by ACPA status. The relative association of RF, ACPA and anti-CarP antibodies with HAQ and DAS28 scores was investigated using a random effects model.  Results: 1995 patients were included; 1310 (66%) were female. Anti-CarP antibodies were significantly associated with more disability and higher disease activity, HAQ multivariate β-coefficient (95% CI) 0.12 (0.02 to 0.21), and these associations remained significant in the ACPA-negative subgroups. The associations of RF, ACPA and anti-CarP antibodies were found to be additive in the random effects model.  Conclusions: Anti-CarP antibodies are associated with increased disability and higher disease activity in patients with IP. Our results suggest that measurement of anti-CarP antibodies may be useful in identifying ACPA-negative patients with worse long-term outcomes. Further, anti-CarP antibody status provided additional information about RF and ACPA

Interobserver Agreement in the Clinical Assessment of Children With Blunt Abdominal Trauma

Objectives The objective was to determine the interobserver agreement of historical and physical examination findings assessed during the emergency department (ED) evaluation of children with blunt abdominal trauma. Methods This was a planned substudy of a multicenter, prospective cohort study of children younger than 18 years of age evaluated for blunt abdominal trauma. Patients were excluded if injury occurred more than 24 hours prior to evaluation or if computed tomography (CT) imaging was obtained at another hospital prior to transfer to a study site. Two clinicians independently recorded their clinical assessments of a convenience sample of patients onto data collection forms within 60 minutes of each other and prior to CT imaging (if obtained) or knowledge of laboratory results. The authors categorized variables as either subjective symptoms (i.e., patient history) or objective findings (i.e., physical examination). For each variable recorded by the two observers, the agreement beyond that expected by chance was estimated, using the kappa (κ) statistic for categorical variables and weighted κ for ordinal variables. Variables with 95% lower confidence limits (LCLs) κ ≥ 0.4 (moderate agreement or better) were considered to have acceptable agreement. Results A total of 632 pairs of physician observations were obtained on 23 candidate variables. Acceptable agreement was achieved in 16 (70%) of the 23 variables tested. For six subjective symptoms, κ ranged from 0.48 (complaint of shortness of breath) to 0.90 (mechanism of injury), and only the complaint of shortness of breath had a 95% LCL κ < 0.4. For the 17 objective findings, κ ranged from –0.01 (pelvis instability) to 0.82 (seat belt sign present). The 95% LCL for κ was <0.4 for flank tenderness, abnormal chest auscultation, suspicion of alcohol or drug intoxication, pelvis instability, absence of bowel sounds, and peritoneal irritation. Conclusions Observers can achieve at least acceptable agreement on the majority of historical and physical examination variables in children with blunt abdominal trauma evaluated in the ED. Those variables are candidates for consideration for development of a clinical prediction rule for intra‐abdominal injury in children with blunt trauma. Resumen Concordancia Interobservador en la Valoración Clínica de los Niños con Traumatismo Abdominal Cerrado Objetivos Determinar la concordancia interobservador de los hallazgos de la historia clínica y la exploración física obtenidos durante la valoración de los niños con traumatismo abdominal de alta energía en el servicio de urgencias (SU). Metodología Se diseñó un subestudio de un estudio de cohorte prospectivo y multicéntrico de niños de 18 años o menos evaluados por traumatismo abdominal cerrado. Se excluyeron los pacientes si el traumatismo había ocurrido más de 24 horas antes de la primera valoración, o si las imágenes de la tomografía computarizada (TC) se obtuvieron en otro hospital previamente a trasladarse al lugar del estudio. Dos clínicos recogieron de forma independiente su valoración clínica en un formulario de datos, de una muestra de conveniencia de pacientes, en los primeros 60 minutos, y previamente a las imágenes de la TC (si ésta se realizó) o al conocimiento de los resultados del laboratorio. Se clasificaron las variables como síntomas subjetivos (ej.: historia del paciente) o hallazgos objetivos (ej.: exploración física). Para cada variable recogida por los dos observadores, se estimó la concordancia más allá de la esperada por el azar usando el índice kappa (κ) para las variables categóricas y índice κ ponderado para las variables ordinales. Se consideró que existía una concordancia aceptable para las variables con una κ ≥ 0,4 (concordancia moderada o buena) en el límite inferior del intervalo de confianza del 95% (IC 95%). Resultados Se obtuvieron 632 pares de observaciones clínicas en 23 variables candidatas. Se alcanzó la concordancia aceptable en 16 (70%) de ellas. Para los seis síntomas subjetivos, el rango de κ fue de 0,48 (queja de dificultad respiratoria) a 0,90 (mecanismo de la lesión), y sólo la queja de dificultad respiratoria tuvo una κ < 0,4 en el límite inferior del IC 95%. Para los 17 hallazgos objetivos, el rango de κ fue desde ‐0,01 (inestabilidad pelvis) a 0,82 (presencia del signo del cinturón de seguridad). El dolor en el flanco, la auscultación torácica alterada, la sospecha de intoxicación por alcohol o tóxicos, la inestabilidad de pelvis, la ausencia de ruidos intestinales y la irritación peritoneal tuvieron una κ < 0,4 en el límite inferior del IC 95%. Conclusiones Los observadores pueden alcanzar al menos una concordancia aceptable en la mayoría de las variables de la historia clínica y la exploración física en los niños con traumatismo abdominal cerrado evaluado en el SU. Estas variables son candidatas para considerarse en el desarrollo de una regla de predicción clínica para la lesión intrabdominal en los niños con traumatismo de cerrado.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/98339/1/acem12132.pd

Association between interleukin-6 gene polymorphisms and rheumatoid arthritis in Chinese Han population: a case-control study and a meta-analysis

The aim of this study was to investigate the possible association in the interleukin-6 (IL-6) gene with Rheumatoid arthritis (RA) in Chinese Han population from Shandong Province. Target regions of IL-6 gene were amplified by polymerase chain reaction (PCR) and genotyped. A logistic regression analysis was performed to detect potential associations in our case-control sample, the odd ratio(OR) and 95% confidence intervals(CIs) were calculated. Furthermore, we systematically tracked all the published studies in the field and performed a meta-analysis for the single nucleotide polymorphisms (SNPs) under study. 256 RA patients and 331 healthy controls were recruited into the case-control study. We found allele frequencies of rs1800795, rs1800797 and rs1474347 in RA patients differ from control subjects (P = 0.016, 0.024, 0.020, respectively). Significant difference was observed in haplotype frequencies of GCCGCT between RA patients and controls (P = 0.0001, OR = 4.066, 95%CI = 1.891 ~ 8.746), while GGCGCT frequencies was found lower in RA than controls (P = 0.006, OR = 0.669, 95%CI = 0.501 ~ 0.894). The results of the meta-analysis showed association polymorphism within the IL-6 promoter with RA. These findings suggest that rare IL-6 gene polymorphisms may associate with RA susceptibility in Han Chinese populations; however further studies are needed to assess the validity of the association of IL-6 with RA

Aggregatibacter actinomycetemcomitans-induced hypercitrullination links periodontal infection to autoimmunity in rheumatoid arthritis

A bacterial etiology of rheumatoid arthritis (RA) has been suspected since the beginnings of modern germ theory. Recent studies implicate mucosal surfaces as sites of disease initiation. The common occurrence of periodontal dysbiosis in RA suggests that oral pathogens may trigger the production of disease-specific autoantibodies and arthritis in susceptible individuals. We used mass spectrometry to define the microbial composition and antigenic repertoire of gingival crevicular fluid in patients with periodontal disease and healthy controls. Periodontitis was characterized by the presence of citrullinated autoantigens that are primary immune targets in RA. The citrullinome in periodontitis mirrored patterns of hypercitrullination observed in the rheumatoid joint, implicating this mucosal site in RA pathogenesis. Proteomic signatures of several microbial species were detected in hypercitrullinated periodontitis samples. Among these, Aggregatibacter actinomycetemcomitans (Aa), but not other candidate pathogens, induced hypercitrullination in host neutrophils. We identified the pore-forming toxin leukotoxin-A (LtxA) as the molecular mechanism by which Aa triggers dysregulated activation of citrullinating enzymes in neutrophils, mimicking membranolytic pathways that sustain autoantigen citrullination in the RA joint. Moreover, LtxA induced changes in neutrophil morphology mimicking extracellular trap formation, thereby releasing the hypercitrullinated cargo. Exposure to leukotoxic Aa strains was confirmed in patients with RA and was associated with both anti-citrullinated protein antibodies (ACPAs) and rheumatoid factor (RF). The effect of HLA-DRB1 shared epitope alleles on autoantibody positivity was limited to RA patients that were exposed to Aa. These studies identify the periodontal pathogen Aa as a candidate bacterial trigger of autoimmunity in RA

Autoantibody Epitope Spreading in the Pre-Clinical Phase Predicts Progression to Rheumatoid Arthritis

Rheumatoid arthritis (RA) is a prototypical autoimmune arthritis affecting nearly 1% of the world population and is a significant cause of worldwide disability. Though prior studies have demonstrated the appearance of RA-related autoantibodies years before the onset of clinical RA, the pattern of immunologic events preceding the development of RA remains unclear. To characterize the evolution of the autoantibody response in the preclinical phase of RA, we used a novel multiplex autoantigen array to evaluate development of the anti-citrullinated protein antibodies (ACPA) and to determine if epitope spread correlates with rise in serum cytokines and imminent onset of clinical RA. To do so, we utilized a cohort of 81 patients with clinical RA for whom stored serum was available from 1–12 years prior to disease onset. We evaluated the accumulation of ACPA subtypes over time and correlated this accumulation with elevations in serum cytokines. We then used logistic regression to identify a profile of biomarkers which predicts the imminent onset of clinical RA (defined as within 2 years of testing). We observed a time-dependent expansion of ACPA specificity with the number of ACPA subtypes. At the earliest timepoints, we found autoantibodies targeting several innate immune ligands including citrullinated histones, fibrinogen, and biglycan, thus providing insights into the earliest autoantigen targets and potential mechanisms underlying the onset and development of autoimmunity in RA. Additionally, expansion of the ACPA response strongly predicted elevations in many inflammatory cytokines including TNF-α, IL-6, IL-12p70, and IFN-γ. Thus, we observe that the preclinical phase of RA is characterized by an accumulation of multiple autoantibody specificities reflecting the process of epitope spread. Epitope expansion is closely correlated with the appearance of preclinical inflammation, and we identify a biomarker profile including autoantibodies and cytokines which predicts the imminent onset of clinical arthritis

Occult Pneumothoraces in Children With Blunt Torso Trauma

Objectives Plain chest x‐ray (CXR) is often the initial screening test to identify pneumothoraces in trauma patients. Computed tomography (CT) scans can identify pneumothoraces not seen on CXR (“occult pneumothoraces”), but the clinical importance of these radiographically occult pneumothoraces in children is not well understood. The objectives of this study were to determine the proportion of occult pneumothoraces in injured children and the rate of treatment with tube thoracostomy among these children. Methods This was a planned substudy from a large prospective multicenter observational cohort study of children younger than 18 years old evaluated in emergency departments (EDs) in the Pediatric Emergency Care Applied Research Network (PECARN) for blunt torso trauma from May 2007 to January 2010. Children with CXRs as part of their trauma evaluations were included for analysis. The faculty radiologist interpretations of the CXRs and any subsequent imaging studies, including CT scans, were reviewed for the absence or presence of pneumothoraces. An “occult pneumothorax” was defined as a pneumothorax that was not identified on CXR, but was subsequently demonstrated on cervical, chest, or abdominal CT scan. Rates of pneumothoraces and placement of tube thoracostomies and rate differences with 95% confidence intervals (CIs) were calculated. Results Of 12,044 enrolled in the parent study, 8,020 (67%) children (median age = 11.3 years, interquartile range [IQR] = 5.3 to 15.2 years) underwent CXRs in the ED, and these children make up the study population. Among these children, 4,276 had abdominal CT scans performed within 24 hours. A total of 372 of 8,020 children (4.6%; 95% CI = 4.2% to 5.1%) had pneumothoraces identified by CXR and/or CT. The CXRs visualized pneumothoraces in 148 patients (1.8%; 95% CI = 1.6% to 2.2%), including one false‐positive pneumothorax, which was identified on CXR, but was not demonstrated on CT. Occult pneumothoraces were present in 224 of 372 (60.2%; 95% CI = 55.0% to 65.2%) children with pneumothoraces. Tube thoracostomies were performed in 85 of 148 (57.4%; 95% CI = 49.0% to 65.5%) children with pneumothoraces on CXR and in 35 of 224 (15.6%; 95% CI = 11.1% to 21.1%) children with occult pneumothoraces (rate difference = –41.8%; 95% CI = –50.8 to –32.3%). Conclusions In pediatric patients with blunt torso trauma, pneumothoraces are uncommon, and most are not identified on the ED CXR. Nearly half of pneumothoraces, and most occult pneumothoraces, are managed without tube thoracostomy. Observation, including in children requiring endotracheal intubation, should be strongly considered during the initial management of children with occult pneumothoraces. Resumen Objetivos La radiografía de tórax simple (RXT) es a menudo la prueba de despistaje inicial para identificar los neumotórax en los pacientes con traumatismo. La tomografía computarizada (TC) puede identificar neumotórax no vistos en la RXT (“neumotórax ocultos”), aunque la importancia clínica de estos neumotórax radiográficamente ocultos en los niños no está muy estudiada. Los objetivos de este estudio fueron determinar la proporción de neumotórax ocultos en los niños accidentados y el porcentaje de tratamiento con tubo de toracostomía en estos niños. Metodología Subestudio diseñado a partir de un gran estudio observacional de cohorte prospectivo multicéntrico de niños menores de 18 años atendidos en los servicios de urgencias (SU) de la Pediatric Emergency Care Applied Research Network (PECARN) que habían sido evaluados por traumatismo torácico cerrado de mayo de 2007 a enero de 2010. Se incluyeron en el análisis los niños en los que la RXT fue parte de la evaluación inicial del traumatismo. Las interpretaciones del radiólogo de las RXT y de cualquier estudio de imagen posterior, incluyendo a TC, se revisaron para la ausencia o presencia de neumotórax. Se definió “neumotórax oculto” como un neumotórax que no fue identificado en la RXT pero que fue posteriormente visualizado en la TC abdominal, torócica o cervical. Se calcularon los porcentajes de neumotórax e inserción de tubo de toracostomía y las diferencias de sus porcentajes con los intervalos de confianza (IC) al 95%. Resultados De los 12.044 incluidos en el estudio principal, se llevo a cabo una RXT en el SU en 8.020 (67%) niños (mediana de edad 11,3 años, rango intercuartílico 5,3 a 15,2), que constituyeron la población de estudio. De estos niños, 4.276 tuvieron una TC realizada en las primeras 24 horas. En 372 de los 8.020 niños (4,6%; IC 95% = 4,2% a 5,1%) se identificó un neumotórax en la RXT y/o la TC. La RXT mostró neumotórax en 148 pacientes (1,8%; IC 95% = 1,6% a 2,2%), incluyendo un falso positivo de neumotórax, que fue identificado en la RXT pero que no fue demostrado en la TC. Los neumotórax ocultos estuvieron presentes en 224 de los 372 niños con neumotórax (60,2%; IC 95% = 55,0% a 65,2%). Se insertaron tubos de toracostomía en 85 de los 148 niños con neumotórax en la RXT (57,4%; IC 95% = 49,0% a 65,5%), y en 35 de los 224 niños con neumotórax oculto (15,6%; IC 95% = 11,1% a 21,1%; diferencia de porcentajes ‐41,8%; IC 95% = ‐50,8 a ‐32,3%). Conclusiones En los pacientes pediátricos con traumatismo torácico cerrado, los neumotórax son poco frecuentes, y la mayoría no son identificados en la RXT en el SU. Casi la mitad de los neumotórax, y la mayoría de los neumotórax ocultos son manejados sin tubo de toracostomía. La observación, incluyendo en los niños que requieren intubación endotraqueal, debería ser especialmente considerada durante el manejo inicial de los niños con neumotórax ocultos.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/106913/1/acem12344.pd

Rheumatoid Factor as a Potentiator of Anti–Citrullinated Protein Antibody–Mediated Inflammation in Rheumatoid Arthritis

Objective. The co-occurrence of rheumatoid factor (RF) and anti–citrullinated protein antibody (ACPA) positivity in rheumatoid arthritis (RA) is well described. However, the mechanisms underlying the potential interaction between these 2 distinct autoantibodies have not been well defined. The aim of this study was to evaluate the epidemiologic and molecular interaction of ACPAs and RF and its association with both disease activity and measures of RA-associated inflammation. Methods. In a cohort of 1,488 US veterans with RA, measures of disease activity and serum levels of cytokines and multiplex ACPAs were compared between the following groups of patients: double-negative (anti–cyclic citrullinated peptide [anti-CCP]-/RF-), anti-CCP+/RF-, anti-CCP-/RF+, or double-positive (anti-CCP+/RF+). Additional studies were performed using an in vitro immune complex (IC) stimulation assay in which macrophages were incubated with ACPA ICs in the presence or absence of monoclonal IgM-RF, and tumor necrosis factor α production measured as a readout of macrophage activation. Results. Compared with the double-negative subgroup (as well as each single-positive subgroup), the double-positive subgroup exhibited higher disease activity as well as higher levels of C-reactive protein and inflammatory cytokines (all P \u3c 0.001). In vitro stimulation of macrophages by ACPA ICs increased cytokine production, and the addition of monoclonal IgM-RF significantly increased macrophage tumor necrosis factor α production (P = 0.003 versus ACPA ICs alone). Conclusion. The combined presence of ACPAs and IgM-RF mediates increased proinflammatory cytokine production in vitro and is associated with increased systemic inflammation and disease activity in RA. Our data suggest that IgM-RF enhances the capacity of ACPA ICs to stimulate macrophage cytokine production, thereby providing a mechanistic link by which RF enhances the pathogenicity of ACPA ICs in RA

Molecular basis for increased susceptibility of Indigenous North Americans to seropositive rheumatoid arthritis

Objective The pathogenetic mechanisms by which HLA-DRB1 alleles are associated with anticitrullinated peptide antibody (ACPA)-positive rheumatoid arthritis (RA) are incompletely understood. RA high-risk HLA-DRB1 alleles are known to share a common motif, the ‘shared susceptibility epitope (SE)’. Here, the electropositive P4 pocket of HLA-DRB1 accommodates self-peptide residues containing citrulline but not arginine. HLA-DRB1 His/Phe13β stratifies with ACPA-positive RA, while His13βSer polymorphisms stratify with ACPA-negative RA and RA protection. Indigenous North American (INA) populations have high risk of early-onset ACPA-positive RA, whereby HLA-DRB1*04:04 and HLA-DRB1*14:02 are implicated as risk factors for RA in INA. However, HLA-DRB1*14:02 has a His13βSer polymorphism. Therefore, we aimed to verify this association and determine its molecular mechanism. Methods HLA genotype was compared in 344 INA patients with RA and 352 controls. Structures of HLA-DRB1*1402-class II loaded with vimentin-64Arg59-71, vimentin-64Cit59-71 and fibrinogen β−74Cit69-81 were solved using X-ray crystallography. Vimentin-64Cit59-71-specific and vimentin59-71-specific CD4+ T cells were characterised by flow cytometry using peptide-histocompatibility leukocyte antigen (pHLA) tetramers. After sorting of antigen-specific T cells, TCRα and β-chains were analysed using multiplex, nested PCR and sequencing. Results ACPA+ RA in INA was independently associated with HLA-DRB1*14:02. Consequent to the His13βSer polymorphism and altered P4 pocket of HLA-DRB1*14:02, both citrulline and arginine were accommodated in opposite orientations. Oligoclonal autoreactive CD4+ effector T cells reactive with both citrulline and arginine forms of vimentin59-71 were observed in patients with HLA-DRB1*14:02+ RA and at-risk ACPA- first-degree relatives. HLA-DRB1*14:02-vimentin59-71-specific and HLA-DRB1*14:02-vimentin-64Cit59-71-specific CD4+ memory T cells were phenotypically distinct populations. Conclusion HLA-DRB1*14:02 broadens the capacity for citrullinated and native self-peptide presentation and T cell expansion, increasing risk of ACPA+ RA

Does the Precision of a Biological Clock Depend upon Its Period? Effects of the Duper and tau Mutations in Syrian Hamsters

Mutations which alter the feedback loops that generate circadian rhythms may provide insight into their insensitivity to perturbation robustness) and their consistency of period (precision). I examined relationships between endogenous period, activity and rest (τDD, α and ρ) in Syrian hamsters using two different mutations, duper and tau, both of which speed up the circadian clock. I generated 8 strains of hamsters that are homozygous or heterozygous for the tau, duper, and wild type alleles in all combinations. The endogenous period of activity onsets among these strains ranged from 17.94+0.04 to 24.13±0.04 h. Contrary to predictions, the variability of period was unrelated to its absolute value: all strains showed similar variability of τDD when activity onsets and acrophase were used as phase markers. The τDD of activity offsets was more variable than onsets but also differed little between genotypes. Cycle variation and precision were not correlated with τDD within any strain, and only weakly correlated when all strains are considered together. Only in animals homozygous for both mutations (super duper hamsters) were cycle variation and precision reduced. Rhythm amplitude differed between strains and was positively correlated with τDD and precision. All genotypes showed negative correlations between α and ρ. This confirms the expectation that deviations in the duration of subjective day and night should offset one another in order to conserve circadian period, even though homeostatic maintenance of energy reserves predicts that longer intervals of activity or rest would be followed by longer durations of rest or activity. Females consistently showed greater variability of the period of activity onset and acrophase, and of α, but variability of the period of offset differed between sexes only in super duper hamsters. Despite the differences between genotypes in τDD, ρ was consistently more strongly correlated with the preceding than the succeeding α