Systemic lupus erythematosus (SLE) is a common systemic autoimmune disease with a complex genetic inheritance. Genome-wide association studies (GWAS) have significantly increased the number of significant loci associated with SLE risk. To date, however, established loci account for less than 30% of the disease heritability and additional risk variants have yet to be identified. Here we performed a GWAS followed by a meta-analysis to identify new genome-wide significant loci for SLE. We genotyped a cohort of 907 patients with SLE (cases) and 1524 healthy controls from Spain and performed imputation using the 1000 Genomes reference data. We tested for association using logistic regression with correction for the principal components of variation. Meta-analysis of the association results was subsequently performed on 7,110,321 variants using genetic data from a large cohort of 4036 patients with SLE and 6959 controls of Northern European ancestry. Genetic association was also tested at the pathway level after removing the effect of known risk loci using PASCAL software. We identified five new loci associated with SLE at the genome-wide level of significance (p < 5 × 10− 8): GRB2, SMYD3, ST8SIA4, LAT2 and ARHGAP27. Pathway analysis revealed several biological processes significantly associated with SLE risk: B cell receptor signaling (p = 5.28 × 10− 6), CTLA4 co-stimulation during T cell activation (p = 3.06 × 10− 5), interleukin-4 signaling (p = 3.97 × 10− 5) and cell surface interactions at the vascular wall (p = 4.63 × 10− 5). Our results identify five novel loci for SLE susceptibility, and biologic pathways associated via multiple low-effect-size loci.

The purpose of this study was to assess the prevalence, associated factors, and impact on mortality of primary respiratory disease in a large systemic lupus erythematosus (SLE) retrospective cohort. All adult patients in the RELESSER-TRANS (Registry of Systemic Lupus Erythematosus Patients of the Spanish Society of Rheumatology [SER], cross-sectional phase) registry were retrospectively investigated for the presence of primary pleuropulmonary manifestations. In total 3215 patients were included. At least one pleuropulmonary manifestation was present in 31% of patients. The most common manifestation was pleural disease (21%), followed by lupus pneumonitis (3.6%), pulmonary thromboembolism (2.9%), primary pulmonary hypertension (2.4%), diffuse interstitial lung disease (2%), alveolar hemorrhage (0.8%), and shrinking lung syndrome (0.8%). In the multivariable analysis, the variables associated with the development of pleuropulmonary manifestation were older age at disease onset (odds ratio (OR) 1.03, 95% confidence interval (CI) 1.02–1.04), higher SLEDAI (Systemic Lupus Erythematosus Disease Activity Index) scores (OR 1.03, 95% CI 1.00–1.07), the presence of Raynaud’s phenomenon (OR 1.41, 95% CI 1.09–1.84), secondary antiphospholipid syndrome (OR 2.20, 95% CI 1.63–2.97), and the previous or concomitant occurrence of severe lupus nephritis, (OR 1.48, 95% CI 1.12–1.95) neuropsychiatric manifestations (OR 1.49, 95% CI 1.11–2.02), non-ischemic cardiac disease (OR 2.91, 95% CI 1.90–4.15), vasculitis (OR 1.81, 95% CI 1.25–2.62), hematological manifestations (OR 1.31, 95% CI 1.00–1.71), and gastrointestinal manifestations, excluding hepatitis (OR 2.05, 95% CI 1.14–3.66). Anti-RNP positivity had a clear tendency to significance (OR 1.32, 95% CI 1.00–1.75; P = 0.054). The development of pleuropulmonary manifestations independently contributes to a diminished survival (hazard ratio of 3.13). However, not all complications will influence the prognosis in the same way. Whereas the occurrence of pleural disease or pulmonary thromboembolism has a minimal impact on the survival of these patients, the remaining manifestations have a major impact on mortality. Except for pleural disease, the remaining respiratory manifestations are very uncommon in SLE (<4%). Pleuropulmonary manifestations independently contributed to a decreased survival in these patients.

Background: B-cell differentiation and B-cell tolerance checkpoints may be different in antiphospholipid syndrome (APS) from systemic lupus erythematosus (SLE) and can help to understand differences between them. Our aim was to define alterations of B-cell subsets in patients with primary APS (pAPS) and to compare them with SLE patients and healthy controls (HC). Methods: Cross-sectional study including three study groups: 37 patients with pAPS, 11 SLE patients, and 21 age- and gender-matched HC. We determined the frequencies of different B-cell subsets in peripheral blood naïve and memory compartments. In addition, we measured serum B cell-activating factor (BAFF) levels and circulating pro-inflammatory cytokines, such as IL-6, by commercial ELISA and CBA, respectively. Results: Patients with pAPS showed a lower percentage of immature and naïve B cells than patients with SLE (p = 0.013 and p = 0.010, respectively) and a higher percentage of non-switched memory B cells than patients with SLE (p = 0.001). No differences either in the percentage of switched memory cells or plasma cells were found among the different groups. Serum BAFF levels were higher in SLE patients than in healthy controls and pAPS patients (p = 0.001 and p = 0.017, respectively). A significant increase in the serum BAFF levels was also observed in pAPS patients compared to HC (p = 0.047). Circulating IL-6 levels were higher in SLE and pAPS patients than HC (p = 0.036 and p = 0.048, respectively). A positive correlation was found between serum BAFF and IL-6 levels in patients with SLE but not in pAPS (p = 0.011). Conclusions: Our characterization of peripheral blood B-cell phenotypes in pAPS demonstrates different frequencies of circulating B cells at different stages of differentiation. These differences in the naïve B-cell repertoire could explain the higher number and variety of autoantibodies in SLE patients in comparison to pAPS patients, especially in those with obstetric complications.

Background: Environmental factors play a central role in seasonal epidemics. SARS-CoV-2 infection in Spain has shown a heterogeneous geographical pattern This study aimed to assess the influence of several climatic factors on the infectivity of SARS-CoV-2 and the severity of COVID-19 among the Spanish Autonomous Communities (AA.CC.). Methods: Data on coronavirus infectivity and severity of COVID-19 disease, as well as the climatic variables were obtained from official sources (Ministry of Health and Spanish Meteorological Agency, respectively). To assess the possible influence of climate on the development of the disease, data on ultraviolet radiation (UVR) were collected during the months before the start of the pandemic. To analyze its influence on the infectivity of SARS-CoV-2, data on UVR, temperature, and humidity were obtained from the months of highest contagiousness to the peak of the pandemic. Results: From October 2019 to January 2020, mean UVR was significantly related not only to SARS-CoV-2 infection (cumulative incidence -previous 14 days- × 10⁵ habitants, rho = − 0.0,666; p = 0.009), but also with COVID-19 severity, assessed as hospital admissions (rho = − 0.626; p = 0.017) and ICU admissions (rho = − 0.565; p = 0.035). Besides, temperature (February: rho = − 0.832; p < 0.001 and March: rho = − 0.904; p < 0.001), was the main climatic factor responsible for the infectivity of the coronavirus and directly contributed to a different spread of SARS-CoV-2 across the Spanish regions. Conclusions: Climatic factors may partially explain the differences in COVID-19 incidence and severity across the different Spanish regions. The knowledge of these factors could help to develop preventive and public health actions against upcoming outbreaks of the disease.

Objectives. It has been suggested that patients with giant cell arteritis (GCA) may share a common pathway with atherosclerosis. Furthermore, patients with GCA and polymyalgia rheumatica (PMR), in addition to advanced age, are treated for prolonged periods of time with corticosteroids, a factor that can also accelerate atherosclerosis. Hyperhomocysteinaemia is considered an independent risk factor for atherosclerosis, and might play a role in ischaemic manifestations that occur with a variable frequency during the course of GCA. The purposes of the present study were: (i) to analyse the plasma levels of homocysteine in patients with GCA and PMR, (ii) to determine the influence of corticosteroid therapy on the homocysteine levels and (iii) to analyse if the levels of homocysteine may predict the development of ischaemic complications in patients with GCA. Methods. Plasma homocysteine concentration was measured in 56 patients with active PMR/GCA (17 GCA and 39 isolated PMR) before steroid treatment and 23 healthy age‐matched volunteers were used as controls. The total plasma homocysteine level was quantified using a fluorescent polarization immunoassay. Results. Homocysteine concentrations were higher in PMR and GCA patients than age‐matched controls (P < 0.05). Patients with GCA had slightly higher levels of plasma homocysteine than those with isolated PMR (13.6±4.3 vs 12.7±3.1 µmol/l, P=0.6). In 30 of these patients (12 GCA and 18 PMR) a second measurement of homocysteine concentration was done when they were in clinical remission with steroid treatment. The post‐treatment levels of homocysteine were significantly increased in GCA rather than in PMR patients. In 13 patients with homocysteine levels above the normal upper limit of our laboratory, therapy with folic acid and/or vitamin B₁₂ was started. After 3 months of vitamin supplements, the homocysteine concentration significantly decreased from 19.2±3.1 to 13.6±3.2 µmol/l (P=0.001). Such decrease was less marked in the PMR than in GCA patients. Ten out of the 17 patients with GCA had ischaemic manifestations of the disease. The levels of homocysteine were slightly higher in GCA patients with ischaemia than in those without ischaemic manifestations, although the difference did not reach statistical significance (15±4.9 vs 11.6±1.9 µmol/l, P=0.46). Conclusions. Patients with active PMR and GCA had elevated plasma concentrations of homocysteine. Corticosteroid therapy significantly increased such levels, especially in GCA patients. Treatment with supplements of folic acid and/or vitamin B₁₂ reduced the homocysteine concentrations. These data support the hypothesis that patients with GCA (and to a lesser extend PMR patients) may share a common pathway with atherosclerosis and suggest a new atherogenic mechanism of corticosteroids.