Shared epitope classification methods according to Gregersen and de Vries allow adequate characterization of patients with rheumatoid arthritis in a Colombian population

Introduction: The most important genetic association in rheumatoid arthritis (RA) is presented with some alleles from the HLA-DRB1 gene that encode the shared epitope (SE). Objectives: To apply the SE classification methods of Gregersen, de Vries, Raychaudhuri, Mattey, and Tezenas du Montcel in a group of Colombian patients with RA and determine the most common HLA-DRB1 alleles in the population. Methods: RA diagnosis, genetic study of the HLA-DRB1 region using Luminex technology in 50 RA and 50 healthy subjects. For the classification analysis, Fisher's exact test and chi-squared test were applied. Tables were created to count the RA-related alleles. We used odds ratio to determine the risk between the presence of the shared epitope (SE) and anti-cyclic citrullinated peptides (Anti-CCP). Results: Gregersen and de Vries methods were suitable for the characterization of RA in this population (p = .006). The most prevalent HLA-DRB1 alleles in the RA group were 14:02,04:04, 08:02,04:05, and 10:01. High frequencies of the 07:01, 03:01,13:02,01:02, and 12:01 HLA-DRB1 alleles were found in the healthy population. HLA-DRB1 alleles with similar distribution in both populations were 04:07, 15:01, 11:01, 16:02, and 01:01. A high frequency of SE + was observed in Anti-CCP + individuals (63.15%); however, this was not statistically significant [OR2.4 (.63-9.01); p = .19]. Conclusion: The SE classification methods of Gregersen and de Vries were adequate in characterizing RA in a Colombian population group. An equivalence of 100% was verified between the susceptibility alleles defined by de Vries and the alleles assigned as SE according to Gregersen.

Introducción: La asociación genética más importante en artritis reumatoide (AR) se presenta con algunos alelos del gen HLA DRB1 que codifican el epítope compartido (EC). Objetivos: Aplicar los métodos de clasificación de EC de Gregersen et al., de Vries et al., Raychaudhuri et al., Mattey et al., y Tezenas du Montcel et al., en un grupo de pacientes colombianos con AR, y determinar los alelos HLA DRB1 más frecuentes en esta población. Métodos: Diagnóstico para AR, estudio genético de la región HLA DRB1 por tecnología Luminex® de 50 sujetos AR y 50 sanos. Para análisis comparativos de clasificaciones EC, se aplicaron las pruebas test exacto de Fisher y Chi-cuadrado y se realizaron tablas de conteos para los alelos relacionados con AR. Se estimó la razón de odds para determinar el riesgo entre la presencia de EC y los anticuerpos antipéptidos cíclicos citrulinados (anti-PCC). Resultados: Los métodos de Gregersen et al. y de Vries et al. fueron adecuados para la caracterización de AR en esta población (p = 0,006). Los alelos HLA DRB1 más prevalentes en el grupo AR fueron 14:02, 04:04, 08:02, 04:05 y 10:01. Se encontraron altas frecuencias de los alelos HLA DRB1 07:01, 03:01,13:02, 01:02 y 12:01 en población sana. Alelos HLA DRB1 con distribución similar en ambas poblaciones fueron: 04:07, 15:01, 11:01, 16:02 y 01:01. Se observó alta frecuencia de individuos EC+ en el grupo AR anti-PCC+ (63,15%); no obstante, sin asociación estadística (OR: 2,4 [0,63-9,01]; p = 0,19). Conclusión: Los métodos de clasificación para EC de Gregersen et al. y de Vries et al. fueron adecuados caracterizando AR en un grupo de población colombiana. Se corroboró equivalencia del 100% entre los alelos de susceptibilidad definidos por de Vries y los alelos asignados como EC según Gregersen et al.

Manifestaciones extrarticulares y anticuerpos contra péptidos cíclicos citrulinados en artritis reumatoide / Extrarticular manifestations and antibodies against citrullinated cyclic peptides in rheumatoid arthritis

Introducción: La artritis reumatoide se manifiesta como enfermedad inflamatoria sistémica presenta manifestaciones extrarticulares. Objetivos: Determinar la frecuencia de manifestaciones extrarticulares en pacientes con artritis reumatoide, identificar las más frecuentes y su asociación con anticuerpos contra péptidos cíclicos citrulinados. Métodos: Se realizó un estudio descriptivo y transversal, en 101 pacientes con diagnóstico de artritis reumatoide, atendidos en La Consulta Protocolizada del Servicio de Reumatología del Hospital Clínico Quirúrgico Hermanos Ameijeiras, entre agosto y diciembre del año 2019. Se identificaron características sociodemográficas como edad, sexo, tiempo de evolución de la artritis reumatoide y tabaquismo. Se buscaron presencia de manifestaciones extrarticulares por el interrogatorio, examen físico y con ayuda de exámenes complementarios y se determinaron los títulos de anticuerpos contra péptidos cíclicos citrulinados en el plasma de los pacientes. Resultados: Las manifestaciones extrarticulares estuvieron presentes en 38 pacientes para 37,6 por ciento de los casos, las más frecuentes fueron los nódulos subcutáneos 37 pacientes, y la anemia en 35 que constituyen 36,6 por ciento y 34,7 por ciento de los casos, respectivamente. Fueron positivos a antipéptidos cíclicos citrulinados 78 enfermos, 77,2 por ciento de la muestra, no existió asociación entre presencia de los antipéptidos cíclicos citrulinados y la actividad de la enfermedad. No existió asociación significativa entre estos anticuerpos y las manifestaciones extrarticulares p<0,0001. Fue significativa la asociación entre los niveles de antipéptidos cíclicos citrulinados y el número de manifestaciones extrarticulares en un paciente p=0,0018. Conclusiones: Las manifestaciones articulares existentes en los pacientes estudiados se asociaron, significativamente, con la presencia de los antipéptidos cíclicos citrulinados(AU)

Introduction: Rheumatoid arthritis within its expression as a systemic inflammatory disease presents extra-articular manifestations. Objectives: To determine the frequency of extra-articular manifestations in patients with rheumatoid arthritis, to identify the most frequent and their association with antibodies against citrullinated cyclic peptides. Methods: A descriptive and cross-sectional study was carried out in 101 patients with a diagnosis of rheumatoid arthritis, assisted in the protocolized consultation of Rheumatology service at Hermanos Ameijeiras Clinical Surgical Hospital, from August to December 2019. Sociodemographic characteristics were identified, such as age, sex, time of evolution of rheumatoid arthritis, smoking habits. The presence of extra-articular manifestations was searched for by questioning, physical examination and with the help of complementary tests, and the titers of antibodies against citrullinated cyclic peptides were determined in the plasma of the patients. Results: Extra-articular manifestations were present in 38 patients, 37.6percent of the cases, the most frequent were subcutaneous nodules in 37 patients, and anemia in 35, which constituted 36.6percent and 34.7percent of the cases, respectively. Seventy eight patients were positive for citrullinated cyclic antipeptides, 77.2percent of the sample, there was no association between the presence of citrullinated cyclic antipeptides and the activity of the disease. There was no significant association between the presence of these antibodies and the presence of extra-articular manifestations p <0.0001, the association between the levels of citrullinated cyclic antipeptides and the number of extra-articular manifestations in a patient was significant p=0.0018. Conclusions: The existing joint manifestations in the studied patients were significantly associated with the presence of citrullinated cyclic antipeptides(AU)

Interpretación de los autoanticuerpos en enfermedades reumatológicas / Interpretation of autoantibodies in rheumatological diseases

RESUMEN Las enfermedades autoinmunes son un grupo de patologías crónicas en las que factores genéticos, ambientales y hormonales contribuyen a su aparición. Además de tener un amplio espectro clínico, la interpretación de los diversos autoanticuerpos y técnicas utilizadas en el laboratorio también son un reto clínico. Dada la complejidad de estas enfermedades, es muy importante apoyarse en las pruebas de laboratorio para establecer un correcto diagnóstico, seguimiento y, en algunos casos inclusive, establecer pronósticos o predicción de la posible aparición de autoinmunidad. Con todo esto se pretende mejorar la calidad de vida de los pacientes disminuyendo la gran morbimortalidad de este grupo de enfermedades, especialmente al diagnosticarlas en etapas tempranas. La mayoría de las enfermedades reumatológicas se caracterizan por la alta producción de autoanticuerpos y reactantes de fase aguda, los cuales están implicados en su fisiopatología produciendo daño directo a nivel sistémico. Entre estas, el lupus eritematoso sistémico, la artritis reumatoide y el síndrome de Sjögren son las más reconocidas. Portales motivos, el objetivo de este trabajo es hacer una revisión que permita guiar tanto a médicos como a personal de laboratorio en la interpretación de los diferentes autoanticuerpos en enfermedades autoinmunes.

ABSTRACT Autoimmune diseases are a group of chronic diseases in which genetic, environmental, and hormonal factors contribute to their appearance. In addition to having a broad clinical spectrum, the interpretation of the various autoantibodies and techniques used in the laboratory is also a clinical challenge. Given the complexity of these diseases, it is very important to rely on the results of laboratory tests to establish a correct diagnosis and follow-up and, in some cases even to establish a prognosis or prediction of autoimmunity. Taking all this into account, it is intended to improve the quality of life of patients by decreasing the increased morbidity and mortality in this group of diseases, especially by early diagnosis. Most rheumatological diseases are characterised by the high production of auto-antibodies and acute phase reactants, which are involved in their pathophysiology, leading to systemic involvement. Among these, the most recognised are, systemic lupus erythematosus, rheumatoid arthritis, and Sjögren's syndrome. For these reasons, the objective of this project is to present a review that will help both physicians and laboratory personnel in the interpretation of the different autoantibodies in autoimmune diseases.

Independence of carbohydrate-deficient isoforms of transferrin and cyclic citrullinated peptides in rheumatoid arthritis / Independência de isoformas de transferrina deficiente em carboidrato e peptídeos citrulinados cíclicos na artrite reumatoide

ABSTRACT Objective: The aim of this study was to assess the relationship between the two types of posttranslational modifications of proteins in RA: glycosylation on the example of carbohydrate-deficient transferrin and citrullination by means of autoantibodies to cyclic citrullinated peptides. Methods: The study was carried out in 50 RA patients. CDT was measured using N Latex CDT immunonephelometric test, the results were presented in absolute and relative units. Anti-CCP were measured using the chemiluminescent method and rheumatoid factor by immunoturbidimetric method. Results: 80% of RA patients were positive for anti-CCP, 70% for RF and 62% for both, anti-CCP and RF. The level of %CDT was significantly elevated, but absolute CDT level was not changed. The mean absolute CDT concentration was higher in anti-CCP positive patients than that in anti-CCP negative. CDT (absolute and relative concentration) did not correlate with anti-CCP and RF. However, serum RF significantly correlated with anti-CCP. %CDT did not correlate with anti-CCP, but absolute level correlated with anti-CCP only in anti-CCP negative and RF negative patients. CDT did not correlate with RF, but solely with anti-CCP in anti-CCP negative patients. Anti-CCP correlated with DAS 28 only in anti-CCP negative RA, but CDT (absolute and relative units) correlated with DAS 28 in all patients and in anti-CCP positive RA. Conclusions: These results suggest that the changes in CDT and anti-CCP concentrations are not associated with oneself and indicate on the independence of these posttranslational modifications in rheumatoid arthritis. Only the alterations in transferrin glycosylation reflected the activity of RA.

RESUMO Objetivo: Avaliar a relação entre os dois tipos de modificações pós-translacionais de proteínas na AR: glicosilação no caso da transferrina deficiente em carboidrato (TDC) e citrulinação por meio dos anticorpos no caso do antipeptídeo citrulinado cíclico (anti-CCP). Métodos: O estudo foi feito em 50 pacientes com AR. A TDC foi medida com o teste imunonefelométrico N Latex CDT e os resultados foram apresentados em unidades absolutas e relativas. O anti-CCP foi mensurado com o método quimioluminescente e o fator reumatoide (FR) pelo método imunoturbidimétrico. Resultados: Dos pacientes com AR, 80% foram positivos para anti-CCP, 70% para FR e 62% para ambos (anti-CCP e FR). A percentagem de transferrina total (%TDC) esteve significativamente elevada, mas o nível absoluto de TDC não esteve alterado. A concentração média de TDC absoluta foi maior nos pacientes anti-CCP positivos do que naqueles anti-CCP negativos. A TDC (concentração absoluta e relativa) não se correlacionou com o anti-CCP e o FR. No entanto, o FR sérico se correlacionou significativamente com o anti-CCP. O percentual de TDC não se correlacionou com o anti-CCP, mas seu nível absoluto se correlacionou com o anti-CCP apenas em pacientes FR negativos e anti-CCP negativos. A TDC não se correlacionou com o FR, somente com o anti-CCP em pacientes anti-CCP negativos. O anti-CCP se correlacionou com o DAS 28 apenas nos pacientes com AR anti-CCP negativos, mas a TDC (unidades absolutas e relativas) se correlacionou com o DAS 28 quando considerados todos os pacientes com AR e em pacientes com AR anti-CCP positivos. Conclusões: Esses resultados sugerem que as alterações na TDC e as concentrações de anti-CCP não estão associadas e indicam a independência dessas modificações pós-translacionais na artrite reumatoide. Apenas as alterações na glicosilação da transferrina refletem a atividade da AR.

Anticuerpos anti-CCP en artritis reumatoidea: relación con características clínicas, citocinas Th1/Th2 y HLA-DRB1 / Anti-cyclic citrullinated peptide antibodies in rheumatoid arthritis: relation with clinical features, cytokines and HLA-DRB1

En el presente estudio se examinó la especificidad y la sensibilidad de los anticuerpos antipéptidos citrulinados cíclicos (CCP) en pacientes latinoamericanas con artritis reumatoidea (AR), así como su relación con la actividad de la enfermedad, manifestaciones extraarticulares (MEA), síntesis de citocinas (IL-4, IL-10, IL-12, TNF-µ e IFN-gamma ) y factor reumatoideo (FR) IgM e IgA, y con el polimorfismo del HLA-DRB1. Se examinaron 79 pacientes con AR (69 con AR establecida y 10 con AR temprana sin previo tratamiento), 56 pacientes con espondilitis anquilosante (EA), 25 con lupus eritematoso sistémico (LES), 50 con síndrome de Sjögren primario (SSp) y diez individuos sanos. De las 69 pacientes con AR establecida, 36 fueron reevaluadas 2 años después. La actividad de la AR se examinó según los criterios del Colegio Americano de Reumatología. Los anticuerpos anti-CCP2, el FR y los niveles de citocinas se determinaron mediante inmunoensayo, y la genotipificación del HLA se llevó a cabo por reacción en cadena de la polimerasa utilizando mezclas de iniciadores específicos. Los anticuerpos anti-CCP se observaron en 96% de los pacientes con AR en la primera evaluación y en 86% en la segunda ( p=0,12), sin modificación significativa en los valores (131±58,7 vs. 130,6±67,1 UI). Su sensibilidad y especificidad global fue de 94% y 92%, respectivamente, pero cuando sólo se consideraron los niveles altos (>60 UI) fueron de 84% y 95%, respectivamente. La razón de probabilidades (RP) positiva fue de 12 y la RP negativa de 0,06. El valor predictivo (VP) positivo fue de 87% y el VP negativo de 96%. Los anticuerpos anti-CCP se observaron en 12% de los pacientes con LES y con SSp, en 2% de los de EA y en 10% de los controles sanos. En los pacientes con AR no se asociaron con la actividad de la enfermedad, MEA y alelos del HLA-DRB1. Tampoco se observaron correlaciones significativas entre sus valores y los niveles de citocinas. En conclusión, los anticuerpos anti-CCP tienen un interés diagnóstico para la AR en nuestra población, pero su utilidad en el seguimiento clínico es limitada y su síntesis es independiente del HLA-DRB1 y no se correlacionan con niveles de citocinas Th1/Th2.

The specificity and sensitivity of anti-cyclic citrullinated peptide antibodies (anti-CCP) was examined in Latin-American patients with rheumatoid arthritis (RA). The variables considered included: 1) relation with the activity of disease, 2) extra-articular manifestations (EAM), 3) synthesis of cytokines (IL-4, IL-10, IL-12, TNF-alpha , and IFN-gamma ) and IgM and IgA rheumatoid factor (RF), and 4) the association with HLA-DRB1 polymorphism. Seventy-nine RA patients were assessed (69 with established RA, and 10 with recent-onset RA not receiving any treatment), 56 with ankylosing spondylitis (AS), 25 with systemic lupus erythematosus (SLE), 50 with primary Sjögren’s syndrome (pSS), and 10 healthy individuals. Of the 69 patients with established RA, 36 were reexamined 2 years later. The activity of the RA was measured by criteria adopted by the American College of Rheumatology. Anti-CCP2, RF and cytokines levels were determined by ELISA. HLA genotypes were established by first, PCR sequence amplification using sequence-specific primers and then, complete sequencing of the product. Anti-CCP antibodies were observed in 96% of patients with RA during the first evaluation and in 86% at the second evaluation ( p=0.12). No significant change in antibody titre was observed between the two evaluations (131±58.7 and 130.6±67.1 IU, respectively). The overall sensitivity and specificity was 94% and 92%, respectively; however, at titres >60 IU, the values were 84% and 95%, respectively. The anti-CCP likelihood ratio positive test was 12 and the likelihood ratio negative test was 0.06. The positive predictive value was 87%, and the negative predictive value was 96%. Anti-CCP antibodies were observed in 12% of SLE and pSS patients, in 2% of AS patients, and in 10% of healthy controls. In RA patients, these antibodies were not associated with the activity of disease, EAM or HLA-DRB1 alleles; no significant correlation was observed between antibody titre and cytokines level. Although anti-CCP antibodies have potential as a diagnostic tool for RA, they are not useful for monitoring clinical activity or predicting the clinical course of disease. Antibody synthesis is HLA-DRB1 independent and not correlated with Th1/Th2 cytokines.