This study aims to analyze in depth the role of IFNα in the upregulation of BLyS in different leukocyte populations and the possible relationship of these molecules with IL-17 and other pathogenic cytokines in SLE. Thus, IFNAR1 and membrane BLyS (mBLyS) expression was upregulated on various blood cell types from patients and closely correlated in all individuals. Moreover, BLyS serum levels associated positively with IFNα and IL-17A amounts, as well as with mBLyS on B cells and neutrophils. Interestingly, mBLyS on neutrophils was also correlated with IL-17A levels. Additionally, intracellular IL-17A expression was increased in both CD4+ lymphocytes and neutrophils from patients, and IL-17+CD4+ T cell frequency was associated with serum IFNα and IFNRA1 expression on B cells. Finally, in vitro assays support an IFNα role in the activation of Th17 cells in SLE. In conclusion, these data suggest that IFNα, BLyS and IL-17 could form a pathological axis in SLE, involving T and B lymphocytes, monocytes, DCs and neutrophils, which act in a vicious circle that encourage the preexisting inflammation and propagate the disease process.

The chronic inflammatory environment associated with systemic lupus erythematosus can lead to an accelerated immunosenescence responsible for the endothelial damage and increased cardiovascular risk observed in these patients. The present study analyzed two populations with opposite effects on vascular endothelium, angiogenic T cells and the senescent CD4(+)CD28(null) subset, in 84 systemic lupus erythematosus patients and 46 healthy controls. Also, 48 rheumatoid arthritis patients and 72 individuals with traditional cardiovascular risk factors participated as disease controls. Phenotypic characterization of CD28(+) and CD28(null) cells was performed by analyzing markers of senescence (CCR7, CD27, CD57) and cytotoxicity (CD56, perforin, granzyme B, IFN-γ). IL-1β, IL-6, IL-8, IL-10, IL-12, IL-17A, IFN-α, IFN-γ, TNF-α, B lymphocyte stimulator, and GM-CSF serum levels were analyzed in systemic lupus erythematosus patients and healthy controls. CD4(+)CD28(null) cells were notably increased in the systemic lupus erythematosus patients and disease controls compared with healthy controls. In contrast, angiogenic T cells were only reduced in the disease controls (those with rheumatoid arthritis or traditional cardiovascular risk factors). Nevertheless, an anomalous presence of CD28(null)-angiogenic T cells, with cytotoxic and senescent characteristics, was noted in systemic lupus erythematosus patients in association with anti-dsDNA titer, anti-SSA/Ro antibodies and circulating TNF-α, IL-8, IFN-α, and B lymphocyte stimulator amounts. This subset was also detected in those with traditional cardiovascular risk factors but not in the rheumatoid arthritis patients. In contrast, CD28(+)-angiogenic T cells were reduced in the systemic lupus erythematosus patients with cardiovascular disorders. In conclusion, CD28 expression must be used to redefine the angiogenic T cell population, because in pathologic conditions, a senescent CD28(null)-angiogenic T cell subset with inflammatory, rather than protective, effects could be present.

Giant cell arteritis (GCA) is the most common form of vasculitis in individuals older than 50 years in Western countries. To shed light onto the genetic background influencing susceptibility for GCA, we performed a genome-wide association screening in a well-powered study cohort. After imputation, 1,844,133 genetic variants were analyzed in 2,134 case subjects and 9,125 unaffected individuals from ten independent populations of European ancestry. Our data confirmed HLA class II as the strongest associated region (independent signals: rs9268905, p = 1.94 × 10, per-allele OR = 1.79; and rs9275592, p = 1.14 × 10, OR = 2.08). Additionally, PLG and P4HA2 were identified as GCA risk genes at the genome-wide level of significance (rs4252134, p = 1.23 × 10, OR = 1.28; and rs128738, p = 4.60 × 10, OR = 1.32, respectively). Interestingly, we observed that the association peaks overlapped with different regulatory elements related to cell types and tissues involved in the pathophysiology of GCA. PLG and P4HA2 are involved in vascular remodelling and angiogenesis, suggesting a high relevance of these processes for the pathogenic mechanisms underlying this type of vasculitis.

Clinical associations of anti-SSA/Ro60 and anti-Ro52/TRIM21 antibodies are not yet fully established. In order to analyse the diagnostic utility of their separate detection, we retrospectively revised the clinical data of 200 anti-SSA/Ro60 and/or anti-Ro52/TRIM21 positive patients identified by line immunoassay during ANA routine detection. Anti-SSA/Ro60 positive patients showed a significantly higher prevalence of autoimmune diseases (AIDs) independently on the presence of anti-Ro52/TRIM21 (OR 3.13, 95% CI 1.10-8.88, p = 0.032). Anti-SSA/Ro60 was independently associated with systemic lupus erythematosus (SLE) when comparing with Sjögren's syndrome (SS) and other systemic AIDs (OR 3.46, 95% CI 1.08-11.06, p = 0.036). The more frequent specificity found in cutaneous lupus erythematosus (CLE) was also anti-SSA/Ro60. In contrast, detection of isolated anti-Ro52/TRIM21 was characteristic of SS (7/35, 20.0%), diffuse cutaneous systemic sclerosis (dcSSc) (3/4, 75.0%), primary biliary cirrhosis (PBC) (4/5, 80.0%) and, specially, of polymyositis/dermatomyositis (PM/DM) (6/6, 100%). In fact, anti-Ro52/TRIM21 was the only antibody detected in 4 out of the 6 PM/DM patients. Malignancies mainly account for the observed high prevalence of mono-specific anti-Ro52/TRIM21 in patients with non-AIDs (10/15, 62.5%). In conclusion, this retrospective study supports the routine distinction of anti-SSA/Ro60 and anti-Ro52/TRIM21 due to their different clinical associations.