A survey of ficolin-3 activity in Systemic Lupus Erythematosus reveals a link to hematological disease manifestations and autoantibody profile.

The complement system plays a central role in the pathogenesis of Systemic Lupus Erythematosus (SLE), but most studies have focused on the classical pathway. Ficolin-3 is the main initiator of the lectin pathway of complement in humans, but its role in systemic autoimmune disease has not been conclusively determined. Here, we combined biochemical and genetic approaches to assess the contribution of ficolin-3 to SLE risk and disease manifestations. Ficolin-3 activity was measured by a functional assay in serum or plasma samples from Swedish SLE patients (n = 786) and controls matched for age and sex (n = 566). Genetic variants in an extended 300 kb genomic region spanning the FCN3 locus were analyzed for their association with ficolin-3 activity and SLE manifestations in a Swedish multicenter cohort (n = 985). Patients with ficolin-3 activity in the highest tertile showed a strong enrichment in an SLE cluster defined by anti-Sm/DNA/nucleosome antibodies (OR 3.0, p < 0.001) and had increased rates of hematological disease (OR 1.4, p = 0.078) and lymphopenia (OR = 1.6, p = 0.039). Genetic variants associated with low ficolin-3 activity mapped to an extended haplotype in high linkage disequilibrium upstream of the FCN3 gene. Patients carrying the lead genetic variant associated with low ficolin-3 activity had a lower frequency of hematological disease (OR 0.67, p = 0.018) and lymphopenia (OR 0.63, p = 0.031) and fewer autoantibodies (p = 0.0019). Loss-of-function variants in the FCN3 gene were not associated with SLE, but four (0.5 %) SLE patients developed acquired ficolin-3 deficiency where ficolin-3 activity in serum was depleted following diagnosis of SLE. Taken together, our results provide genetic and biochemical evidence that implicate the lectin pathway in hematological SLE manifestations. We also identify lectin pathway activation through ficolin-3 as a factor that contributes to the autoantibody response in SLE.

Belimumab and antimalarials combined against renal flares in patients treated for extra-renal systemic lupus erythematosus: results from 4 phase III clinical trials.

OBJECTIVES: To determine the effect of antimalarial agents (AMA) and different doses and pharmaceutical forms of belimumab on preventing renal flares in patients with SLE treated for extra-renal disease. METHODS: We pooled data from the BLISS-52, BLISS-76, BLISS-SC and BLISS-Northeast Asia trials of belimumab (n = 3225), that included patients with active SLE yet no severe ongoing nephritis. Participants were allocated to receive intravenous belimumab 1 mg/kg, intravenous belimumab 10 mg/kg, subcutaneous belimumab 200 mg, or placebo in addition to standard therapy. We estimated hazards of renal flare development throughout the study follow-up (52-76 weeks) using Cox regression analysis. RESULTS: In total, 192 patients developed a renal flare after a median of 197 days. Compared with placebo, the risk of renal flares was lower among patients receiving intravenous belimumab 10 mg/kg (HR: 0.62; 95% CI: 0.41, 0.92; P = 0.018) and intravenous belimumab 1 mg/kg (HR: 0.42; 95% CI: 0.22, 0.79; P = 0.007), while no significant association was found for subcutaneous belimumab 200 mg. AMA use yielded a lower hazard of renal flares (HR: 0.66; 95% CI: 0.55, 0.78; P < 0.001). The protection conferred was enhanced when belimumab and AMA were co-administered; the lowest flare rate was observed for the combination intravenous belimumab 1 mg/kg and AMA (18.5 cases per 1000 person-years). CONCLUSIONS: The protection conferred from belimumab against renal flare development in patients treated for extra-renal SLE appears enhanced when belimumab was administered along with AMA. The prominent effect of low-dose belimumab warrants investigation of the efficacy of intermediate belimumab doses. CLINICAL TRIAL IDENTIFICATION: BLISS-52: NCT00424476; BLISS-76: NCT00410384; BLISS-SC: NCT01484496; BLISS-NEA: NCT01345253.

Lupus Low Disease Activity State and organ damage in relation to quality of life in systemic lupus erythematosus: a cohort study with up to 11 years of follow-up.

OBJECTIVES: Beyond prevention of organ damage, treatment goals in systemic lupus erythematosus (SLE) include optimisation of health-related quality of life (HRQoL). The Lupus Low Disease Activity State (LLDAS) has received increasing attention as a goal whenever remission cannot be achieved. How SLE disease activity, organ damage, and LLDAS attainment relate to patient-reported outcomes (PROs) is not fully explored, which formed the scope of this investigation. METHODS: We included 327 patients with SLE from a tertiary referral centre. Longitudinal registrations of disease activity using SLEDAI-2K and physician global assessment (PhGA), organ damage using the SLICC/ACR damage index (SDI), pharmacotherapies, EQ-5D-3L data, as well as visual analogue scale (VAS) scores for fatigue, pain, and overall SLE-related health state over a median follow-up time of 8.5 years were analysed. RESULTS: In the overall population, as well as subgroups of patients with recent-onset SLE and those with clinically active, autoantibody-positive disease, LLDAS attainment, lower PhGA, and lower clinical SLEDAI-2K scores were associated with favourable HRQoL by EQ-5D-3L and VAS assessments, while increasing SDI scores were associated with poor PROs yet not fatigue in the overall population. PROs were further enhanced by being in LLDAS sustainedly. In fully adjusted models of the entire study population, LLDAS attainment and lower disease activity were associated with favourable PROs, irrespective of SDI. CONCLUSION: In one of the longest to date observational studies, we demonstrated that low disease activity and being sustainedly in LLDAS were coupled with favourable HRQoL, pain, fatigue, and overall health experience, irrespective of organ damage.

Autoantibodies to joint-related peptides as predictive markers in early rheumatoid arthritis.

OBJECTIVE: For better management of rheumatoid arthritis (RA), new biomarkers are needed to predict the development of different disease courses. This study aims to identify autoantibodies against epitopes on proteins in the joints and to predict disease outcome in patients with new onset RA. METHODS: Sera from new onset RA patients from the Swedish BARFOT and TIRA-2 cohorts (n = 1986) were screened for autoantibodies to selected peptides (JointIDs) in a bead-based multiplex flow immunoassay. Disease outcomes included Boolean remission 1.0, swollen joint count and radiographic destruction. Multivariate logistic regression and zero-inflated negative binomial models that accounted for clinical factors were used to identify JointIDs with the strongest potential to predict prognosis. RESULTS: Boolean remission was predicted with 42% sensitivity and 75% specificity in male patients positive for antibodies to a non-modified collagen type II (COL2) peptide at 12 months. When antibodies to a specific citrullinated cartilage oligomeric protein (COMP) peptide were absent and the patient was in Boolean remission at 6 months, the sensitivity was 13% and the specificity 99%. Positivity for the non-modified COL2 peptide also reduced the frequency of swollen joints by 41% and 33% at 6 and 12 months, respectively. Antibodies to cyclic citrullinated peptides (aCCP) predicted joint destruction with low specificity (58%). Positivity for a COL2 and a glucose-6-phosphate dehydrogenase peptide in citrullinated forms increased specificity (86%) at the expense of sensitivity (39%). CONCLUSION: Autoantibodies against joint-related proteins at RA diagnosis predict remission with high specificity and, in combination with clinical factors, may guide future treatment decisions.

Plasma interferon-alpha protein levels during pregnancy are associated with lower birth weight in systemic lupus erythematosus.

OBJECTIVES: Adverse pregnancy outcomes are more common in women with systemic lupus erythematosus (SLE) compared with healthy women, but we lack prognostic biomarkers. Plasma interferon alpha (IFNα) protein levels are elevated in a subgroup of pregnant women with SLE, but whether this is associated with pregnancy outcomes is unknown. We investigated the relationship between IFNα, adverse pregnancy outcomes and the presence of autoantibodies in SLE pregnancy. METHODS: We followed 76 women with SLE prospectively. Protein levels of IFNα were quantified in plasma collected in the 2nd and 3rd trimester with single-molecule array. Positivity for antinuclear and antiphospholipid antibodies was assessed during late pregnancy with multiplexed bead assay. Clinical outcomes included the adverse pregnancy outcomes small for gestational age (SGA), preterm birth, and preeclampsia. RESULTS: During SLE pregnancy, women with SGA infants compared with those without had higher levels of plasma IFNα protein, and IFNα positivity was associated with lower birth weight of the infant. Preterm birth was associated with autoantibodies against chromatin. IFNα protein levels associated positively with autoantibodies against chromatin, Smith/ribonucleoprotein (SmRNP) and RNP, but negatively with phospholipid antibodies. CONCLUSION: Elevated IFNα protein in plasma of women with SLE is a potential risk factor for lower birth weight of their infants. The association between IFNα and lower birth weight warrants further investigation regarding the pathophysiological role of IFNα during SLE pregnancy.

Obesity and tobacco smoking are independently associated with poor patient-reported outcomes in SLE: a cross-sectional study.

We investigated associations of obesity and tobacco smoking with health-related quality of life (HRQoL), pain, fatigue, and functional impairment in systemic lupus erythematosus (SLE). Furthermore, we explored whether there was an effect modification between these two factors. We included adult SLE patients from the Linköping University Hospital (n = 325) in the present cross-sectional analysis. We further included population-based controls and performed cardinality matching to balance age and sex distributions with cases (n = 224). HRQoL was assessed with the EQ-5D index score; pain, fatigue, and overall SLE-related health state with visual analogue scales (VAS; 0 [best] to 100 [worst]); and functional impairment with the HAQ-DI. Unacceptable outcomes were defined as VAS scores corresponding to the 90th percentile derived from the matched controls. SLE patients reported worse scores than controls in all measures, and approximately 30% experienced unacceptable outcomes. When compared with normal-weight, obese SLE patients reported lower HRQoL, and greater functional impairment and risk of unacceptable pain (OR: 3.2; 95% CI 1.6-6.7) and fatigue (OR: 2.1; 95% CI 1.0-4.3). Similarly, the current smokers reported higher levels of functional impairment and a greater risk of unacceptable pain (OR: 3.8; 95% CI 1.8-8.2) and fatigue (OR: 2.8; 95% CI 1.3-5.9) than never smokers. The associations were independent of age, sex, disease duration, disease activity, and organ damage. There was no evidence of a synergistic effect between increased BMI and smoking on any outcome. In summary, obesity and smoking are risk factors for unacceptable patient-reported outcomes in SLE, regardless of clinical activity.

The prevalence of neutropenia and association with infections in patients with systemic lupus erythematosus: a Swedish single-center study conducted over 14 years.

Hematologic abnormalities are common manifestations of SLE, although neutropenia is observed less frequently and is not included in the classification criteria. Nonetheless, neutropenia is a risk factor for infections, especially those caused by bacteria or fungi. We aimed to evaluate the impact of neutropenia in SLE through a systematic investigation of all infections in a large cohort of well-characterized patients, focusing on neutropenia, lymphopenia, and hypocomplementemia. Longitudinal clinical and laboratory parameters obtained at visits to the Rheumatology Unit, Linköping University Hospital, and linked data on all forms of healthcare utilization for all the subjects included in our regional SLE register during 2008-2022 were assessed. Data regarding confirmed infections were retrieved from the medical records. Overall, 333 patients were included and monitored during 3,088 visits to a rheumatologist during the study period. In total, 918 infections were identified, and 94 occasions of neutropenia (ANC < 1.5 × 109/L) were detected in 40 subjects (12%). Thirty neutropenic episodes in 15 patients occurred in association with infections, of which 13 (43%) required in-hospital care, 4 (13%) needed intensive care, and 1 (3%) resulted in death. Bayesian analysis showed that patients with ≥ 1 occasion of neutropenia were more likely to experience one or more infections (OR = 2.05; probability of association [POA] = 96%). Both invasiveness (OR = 7.08; POA = 98%) and severity (OR = 2.85; POA = 96%) of the infections were significantly associated with the present neutropenia. Infections are common among Swedish SLE patients, 12% of whom show neutropenia over time. Importantly, neutropenia is linked to both the invasiveness and severity of infections. Awareness of the risks of severe infections in neutropenic patients is crucial to tailor therapies to prevent severe illness and death.

Immune Mechanisms and Biomarkers in Systemic Lupus Erythematosus.

The immense heterogeneity of the chronic, inflammatory, autoimmune disease systemic lupus erythematosus (SLE), both with regard to immunological aberrancies and clinical manifestations, poses diagnostic difficulties and challenges in the management of patients [...].

Conformational state of C-reactive protein is critical for reducing immune complex-triggered type I interferon response: Implications for pathogenic mechanisms in autoimmune diseases imprinted by type I interferon gene dysregulation.

Presence of autoantibodies targeting nuclear constituents, i.e., double-stranded DNA and small nuclear ribonucleoproteins (snRNPs), remain a cornerstone in systemic lupus erythematosus (SLE). Fcγ receptor IIa (FcγRIIa) dependent uptake of nucleic acid containing immune complexes (ICs) by plasmacytoid dendritic cells (PDCs) can activate toll-like receptors (TLRs) such as TLR7 and TLR9 resulting in type I interferon (IFN) production. Previously, the classical liver-derived acute-phase reactant C-reactive protein (CRP) has been suggested to reduce IC-induced type I IFN production, whereas monomeric (mCRP) vs. pentameric (pCRP) mediated effects have not yet been unraveled. Herein, peripheral blood mononuclear cells (PBMCs) or enriched blood DCs from healthy volunteers were stimulated with SLE sera, snRNP-IgG (ICs), or TLR ligands with or without pCRP, mCRP, or anti-FcγRIIa antibody. Type I IFNs and cytokine responses were investigated using quantitative PCR, ELISA, and flow cytometry. pCRP inhibited IFN gene expression in PBMCs and enriched DCs after incubation with ICs, compared to ICs alone, whereas mCRP had significantly less inhibitory effect. The effect was independent on the order in which IC or CRP was added to the cells. In addition, pCRP inhibited IFN induced by other TLR stimulators, implicating broader inhibitory effects induced by pCRP. We demonstrate pronounced immunoregulatory functions of CRP whereas the inhibitory properties were evidently dependent on CRP's intact conformational state. The inhibition of type I IFNs was not due to competition of FcγRs, or binding of CRP to the ICs. Our findings have implications for autoimmune IC-mediated conditions imprinted by type I IFN gene dysregulation.

Extracellular vesicles opsonized by monomeric C-reactive protein (CRP) are accessible as autoantigens in patients with systemic lupus erythematosus and associate with autoantibodies against CRP.

The pentraxin C-reactive protein (CRP) is a pentameric protein now known to be able to undergo dissociation into a monomeric, modified isoform, referred to as mCRP. In carefully assessing the bioactivities of each isoform, mCRP has strong pro-inflammatory activities while pCRP has mild anti-inflammatory activities. Systemic lupus erythematosus (SLE) is a disease characterized by a vast number of autoantibodies, including anti-CRP autoantibodies which have been associated with SLE disease activity and lupus nephritis. The origin of these autoantibodies is currently unknown. Extracellular vesicles (EVs) have been implicated in SLE pathogenesis as they can expose nuclear antigens on their outside surface, thereby being a potential adjuvant for the generation of autoantibodies. Herein, we studied exposure of both pCRP and mCRP on EVs in SLE plasma and the implications of each in disease activity, organ damage and clinical manifestations. We used flow cytometry to detect CRP isoforms on EV surfaces in 67 well-characterized SLE patients and 60 sex- and age-matched healthy controls. Autoantibodies against mCRP were measured using ELISA. We found an abundance of both pCRP and mCRP on SLE EVs compared to controls. Furthermore, mCRP+ but not pCRP+ EVs were elevated in patients with active disease and in anti-CRP positive patients. The proportions of mCRP+ EVs were lower in patients with acquired organ damage, especially in patients with lupus nephritis (LN), and displayed an inverse relationship with disease duration in LN and patients with active disease. Speculatively, these data suggest EV-bound mCRP as a relevant factor in SLE pathogenesis, which could contribute to development of anti-CRP autoantibodies by stimulating an immune response.

Doubtful Clinical Value of Subtyping Anti-U1-RNP Antibodies Regarding the RNP-70 kDa Antigen in Sera of Patients with Systemic Lupus Erythematosus.

The detection of antinuclear antibodies is central to the diagnosis and prognosis of systemic lupus erythematosus (SLE), primary Sjögren's syndrome (pSS) and mixed connective tissue disease (MCTD). Anti-U1-RNP and anti-RNP70 antibodies were assayed in the sera of patients with SLE (n = 114), pSS (n = 54) and MCTD (n = 12). In the SLE group, 34/114 (30%) were anti-U1-RNP positive, and 21/114 (18%) were both anti-RNP70 positive and anti-U1-RNP positive. In the MCTD group, 10/12 (83%) were anti-U1-RNP positive, and 9/12 (75%) were anti-RNP70 positive. Only one individual with pSS was antibody positive (for both anti-U1-RNP and anti-RNP70). All anti-RNP70-positive samples were also anti-U1-RNP positive. Anti-U1-RNP-positive subjects with SLE were younger (p < 0.0001); showed lower concentrations of complement protein 3 (p = 0.03); had lower eosinophil (p = 0.0005), lymphocyte (p = 0.006) and monocyte (p = 0.03) counts; and had accrued less organ damage (p = 0.006) than the anti-U1-RNP-negative SLE patients. However, we observed no significant clinical or laboratory parameter differences between the anti-U1-RNP-positive individuals with/without anti-RNP70 in the SLE group. In conclusion, anti-RNP70 antibodies are not exclusive to MCTD but are rarely detected in pSS and healthy individuals. In SLE, anti-U1-RNP antibodies are associated with a clinical phenotype that resembles MCTD, with hematologic involvement and less damage accrual. Based on our results, the clinical value of subtyping anti-RNP70 in anti-U1-RNP-positive sera appears to be of limited value.

Limited Association between Antibodies to Oxidized Low-Density Lipoprotein and Vascular Affection in Patients with Established Systemic Lupus Erythematosus.

Patients with systemic lupus erythematosus (SLE) are at an increased risk of cardiovascular disease. We aimed to evaluate whether antibodies to oxidized low-density lipoprotein (anti-oxLDL) were associated with subclinical atherosclerosis in patients with different SLE phenotypes (lupus nephritis, antiphospholipid syndrome, and skin and joint involvement). Anti-oxLDL was measured by enzyme-linked immunosorbent assay in 60 patients with SLE, 60 healthy controls (HCs) and 30 subjects with anti-neutrophil cytoplasmic antibody-associated vasculitis (AAV). Intima-media thickness (IMT) assessment of vessel walls and plaque occurrence were recorded using high-frequency ultrasound. In the SLE cohort, anti-oxLDL was again assessed in 57 of the 60 individuals approximately 3 years later. The levels of anti-oxLDL in the SLE group (median 5829 U/mL) were not significantly different from those in the HCs group (median 4568 U/mL), while patients with AAV showed significantly higher levels (median 7817 U/mL). The levels did not differ between the SLE subgroups. A significant correlation was found with IMT in the common femoral artery in the SLE cohort, but no association with plaque occurrence was observed. The levels of anti-oxLDL antibodies in the SLE group were significantly higher at inclusion compared to 3 years later (median 5707 versus 1503 U/mL, p < 0.0001). Overall, we found no convincing support for strong associations between vascular affection and anti-oxLDL antibodies in SLE.

Standardisation of ACPA tests: evaluation of a new candidate reference preparation.

INTRODUCTION: Commercial assays measuring antibodies to citrullinated protein/peptide (ACPA) show poor quantitative agreement. The diagnostic industry has never adopted the International Union of Immunological Societies-Centers for Disease Control and Prevention (IUIS-CDC) ACPA reference standard. Recently, the National Institute for Biological Standards and Control (NIBSC) prepared a new candidate ACPA standard (18/204). We evaluated both reference materials using different commercially available ACPA assays. MATERIALS AND METHODS: This is an international study in which the NIBSC candidate ACPA standard and the IUIS-CDC ACPA reference material were analysed together with 398 diagnostic samples from individuals with rheumatoid arthritis (RA) and in 1073 individuals who did not have RA using nine commercial ACPA assays. RESULTS: For both reference materials and samples from individuals with RA and individuals who did not have RA, there were large differences in quantitative ACPA results between assays. For most assays, values for the IUIS-CDC standard were lower than values for NIBSC 18/204 and the IUIS-CDC/NIBSC ratio was comparable for several, but not all assays. When NIBSC 18/204 was used as a calibrator, an improvement in alignment of ACPA results across several of the evaluated assays was obtained. Moreover, NIBSC 18/204 could align clinical interpretation for some but not all assays. CONCLUSION: Adoption of an international standard for ACPA determination is highly desirable. The candidate NIBSC 18/204 standard improved the standardisation and alignment of most ACPA assays and might therefore be recommended to be used as reference in commercial assays.

Comparison of treatment retention of originator vs biosimilar products in clinical rheumatology practice in Sweden.

OBJECTIVES: To compare treatment retention between biosimilars and their originator products among first starters (etanercept, infliximab, adalimumab and rituximab), as well as after non-medical switch. METHODS: Patients with rheumatic diseases starting, for the first time, an originator or biosimilar etanercept, infliximab, adalimumab or rituximab were identified in the national Swedish Rheumatology Quality Register. Moreover, patients switching from an originator to its biosimilar were identified and individually matched to patients continuing on the originator. One-year treatment retention was calculated and hazard ratios (HR) for discontinuation with 95% CIs were estimated, adjusting for comorbidities and socio-economic factors. RESULTS: In total, 21 443 first treatment courses were identified. The proportion of patients still on the drug at 1 year and the HR for discontinuation revealed no differences across adalimumab (Humira, Imraldi, Amgevita and Hyrimoz) nor across rituximab products (Mabthera, Ritemvia/Truxima and Rixathon). The proportions on the drug at 1 year were similar for Benepali (77%) and Enbrel (75%) and the adjusted HR for Benepali compared with Enbrel was 0.91 (95% CI 0.83, 0.99). For infliximab, the proportion still on the drug at 1 year was 67% for Remicade and 66% for Remsima/Inflectra and the HR compared with Remicade was 1.16 (95% CI 1.02, 1.33). Among 2925 patients switching from an originator drug to one of its biosimilars, we noted no statistically significant or clinically relevant differences in drug survival compared with those who remained on originator therapy. CONCLUSION: This large observational study supports the equivalence of biologic DMARD biosimilar products and originators when used in routine rheumatology care.

IgA rheumatoid factor in rheumatoid arthritis.

OBJECTIVES: Rheumatoid factor (RF) is a well-established marker for the diagnosis and classification of rheumatoid arthritis (RA). Most studies evaluated IgM RF or isotype-nonspecific total RF assays. We evaluated the added value of IgA RF in this context. METHODS: An international sample cohort consisting of samples from 398 RA patients and 1073 controls was tested for IgA RF with 3 commercial assays. For all RA patients and 100 controls essential clinical and serological data for ACR/EULAR classification were available. RESULTS: The sensitivity of IgA RF for diagnosing RA was lower than the sensitivity of IgM RF. Differences in numerical values between IgA RF assays were observed. With all assays, the highest IgA RF values were found in patients with primary Sjögren's syndrome. Double positivity for IgM RF and IgA RF had a higher specificity for RA than either IgM RF or IgA RF. The sensitivity of double positivity was lower than the sensitivity of either IgA RF or IgM RF. Single positivity for IgA RF was at least as prevalent in controls than in RA patients. Adding IgA RF to IgM RF and anti-citrullinated protein antibodies (ACPA) did not affect RA classification. However, combined positivity for IgA RF, IgM RF and IgG ACPA had a higher specificity and lower sensitivity for RA classification than positivity for either of the antibodies. CONCLUSIONS: IgA RF showed a lower sensitivity than IgM RF. Combining IgA RF with IgM RF and ACPA did not improve sensitivity of RA classification. Combined positivity (IgA-RF/IgM-RF/ACPA) increased specificity.

B Cell Kinetics upon Therapy Commencement for Active Extrarenal Systemic Lupus Erythematosus in Relation to Development of Renal Flares: Results from Three Phase III Clinical Trials of Belimumab.

Renal flares constitute major determinants of poor prognosis in people living with systemic lupus erythematosus (SLE). The aim of the present study was to investigate changes in B cell subsets in relation to renal flares upon initiation of standard therapy (ST) plus belimumab or placebo in patients with SLE. Using data from the BLISS-76, BLISS-SC, and BLISS Northeast Asia trials, we investigated associations of relative to baseline rapid (through week 8) and early (through week 24) percentage changes in circulating CD19+ B cell subsets characterised through flow cytometry, anti-dsDNA antibodies, and complement levels with the occurrence of renal flares over one year. Patients who developed renal flares showed more prominent rapid decreases in CD19+CD20+CD138+ short-lived plasma cells (-50.4% vs. -16.7%; p = 0.019) and CD19+CD20-CD27bright plasmablasts (-50.0% vs. -29.9%; p = 0.020) compared to non-flaring patients, followed by a subsequent return. Less prominent rapid reductions in CD19+CD27-CD24brightCD38bright transitional B cells (-42.9% vs. -75.0%; p = 0.038) and CD19+CD20-CD138+ peripheral long-lived plasma cells (-11.3% vs. -29.2%; p = 0.019) were seen in belimumab-treated-but not placebo-treated-patients who developed renal flares compared to belimumab-treated patients who did not. Rapid and early changes in anti-dsDNA or complement levels showed no clear association with renal flares. In summary, a rapid drop followed by a subsequent return in circulating short-lived plasma cells and plasmablasts upon treatment for active extra-renal SLE portended renal flares, indicating a need for therapeutic adjustments in patients showing such B cell patterns. Rapid decreases in transitional B cells and peripheral long-lived plasma cells upon belimumab therapy commencement may signify a greater protection against renal flares. B cell kinetics may prove useful in early drug evaluation.

Variants in BANK1 are associated with lupus nephritis of European ancestry.

The genetic background of lupus nephritis (LN) has not been completely elucidated. We performed a case-only study of 2886 SLE patients, including 947 (33%) with LN. Renal biopsies were available from 396 patients. The discovery cohort (Sweden, n = 1091) and replication cohort 1 (US, n = 962) were genotyped on the Immunochip and replication cohort 2 (Denmark/Norway, n = 833) on a custom array. Patients with LN, proliferative nephritis, or LN with end-stage renal disease were compared with SLE without nephritis. Six loci were associated with LN (p < 1 × 10-4, NFKBIA, CACNA1S, ITGA1, BANK1, OR2Y, and ACER3) in the discovery cohort. Variants in BANK1 showed the strongest association with LN in replication cohort 1 (p = 9.5 × 10-4) and proliferative nephritis in a meta-analysis of discovery and replication cohort 1. There was a weak association between BANK1 and LN in replication cohort 2 (p = 0.052), and in the meta-analysis of all three cohorts the association was strengthened (p = 2.2 × 10-7). DNA methylation data in 180 LN patients demonstrated methylation quantitative trait loci (meQTL) effects between a CpG site and BANK1 variants. To conclude, we describe genetic variations in BANK1 associated with LN and evidence for genetic regulation of DNA methylation within the BANK1 locus. This indicates a role for BANK1 in LN pathogenesis.

Interaction between the STAT4 rs11889341(T) risk allele and smoking confers increased risk of myocardial infarction and nephritis in patients with systemic lupus erythematosus.

OBJECTIVE: To investigate how genetics influence the risk of smoking-related systemic lupus erythematosus (SLE) manifestations. METHODS: Patients with SLE (ndiscovery cohort=776, nreplication cohort=836) were genotyped using the 200K Immunochip single nucleotide polymorphisms (SNP) Array (Illumina) and a custom array. Sixty SNPs with SLE association (p<5.0×10-8) were analysed. Signal transducer and activator of transcription 4 (STAT4) activation was assessed in in vitro stimulated peripheral blood mononuclear cells from healthy controls (n=45). RESULTS: In the discovery cohort, smoking was associated with myocardial infarction (MI) (OR 1.96 (95% CI 1.09 to 3.55)), with a greater effect in patients carrying any rs11889341 STAT4 risk allele (OR 2.72 (95% CI 1.24 to 6.00)) or two risk alleles (OR 8.27 (95% CI 1.48 to 46.27)).Smokers carrying the risk allele also displayed an increased risk of nephritis (OR 1.47 (95% CI 1.06 to 2.03)). In the replication cohort, the high risk of MI in smokers carrying the risk allele and the association between the STAT4 risk allele and nephritis in smokers were confirmed (OR 6.19 (95% CI 1.29 to 29.79) and 1.84 (95% CI 1.05 to 3.29), respectively).The interaction between smoking and the STAT4 risk allele resulted in further increase in the risk of MI (OR 2.14 (95% CI 1.01 to 4.62)) and nephritis (OR 1.53 (95% CI 1.08 to 2.17)), with 54% (MI) and 34% (nephritis) of the risk attributable to the interaction. Levels of interleukin-12-induced phosphorylation of STAT4 in CD8+ T cells were higher in smokers than in non-smokers (mean geometric fluorescence intensity 1063 vs 565, p=0.0063).Lastly, the IL12A rs564799 risk allele displayed association with MI in both cohorts (OR 1.53 (95% CI 1.01 to 2.31) and 2.15 (95% CI 1.08 to 4.26), respectively). CONCLUSIONS: Smoking in the presence of the STAT4 risk gene variant appears to increase the risk of MI and nephritis in SLE. Our results also highlight the role of the IL12-STAT4 pathway in SLE-cardiovascular morbidity.

Impact of the COVID-19 pandemic on morbidity and mortality in patients with inflammatory joint diseases and in the general population: a nationwide Swedish cohort study.

OBJECTIVES: To estimate absolute and relative risks for all-cause mortality and for severe COVID-19 in inflammatory joint diseases (IJDs) and with antirheumatic therapies. METHODS: Through Swedish nationwide multiregister linkages, we selected all adult patients with rheumatoid arthritis (RA, n=53 455 in March 2020), other IJDs (here: spondyloarthropathies, psoriatic arthritis and juvenile idiopathic arthritis, n=57 112), their antirheumatic drug use, and individually matched population referents. We compared annual all-cause mortality March-September 2015 through 2020 within and across cohorts, and assessed absolute and relative risks for hospitalisation, admission to intensive care and death due to COVID-19 March-September 2020, using Cox regression. RESULTS: During March-September 2020, the absolute all-cause mortality in RA and in other IJDs was higher than 2015-2019, but relative risks versus the general population (around 2 and 1.5) remained similar during 2020 compared with 2015-2019. Among patients with IJD, the risks of hospitalisation (0.5% vs 0.3% in their population referents), admission to intensive care (0.04% vs 0.03%) and death (0.10% vs 0.07%) due to COVID-19 were low. Antirheumatic drugs were not associated with increased risk of serious COVID-19 outcomes, although for certain drugs, precision was limited. CONCLUSIONS: Risks of severe COVID-19-related outcomes were increased among patients with IJDs, but risk increases were also seen for non-COVID-19 morbidity. Overall absolute and excess risks are low and the level of risk increases are largely proportionate to those in the general population, and explained by comorbidities. With possible exceptions, antirheumatic drugs do not have a major impact on these risks.

Molecular pathways in patients with systemic lupus erythematosus revealed by gene-centred DNA sequencing.

OBJECTIVES: Systemic lupus erythematosus (SLE) is an autoimmune disease with extensive heterogeneity in disease presentation between patients, which is likely due to an underlying molecular diversity. Here, we aimed at elucidating the genetic aetiology of SLE from the immunity pathway level to the single variant level, and stratify patients with SLE into distinguishable molecular subgroups, which could inform treatment choices in SLE. METHODS: We undertook a pathway-centred approach, using sequencing of immunological pathway genes. Altogether 1832 candidate genes were analysed in 958 Swedish patients with SLE and 1026 healthy individuals. Aggregate and single variant association testing was performed, and we generated pathway polygenic risk scores (PRS). RESULTS: We identified two main independent pathways involved in SLE susceptibility: T lymphocyte differentiation and innate immunity, characterised by HLA and interferon, respectively. Pathway PRS defined pathways in individual patients, who on average were positive for seven pathways. We found that SLE organ damage was more pronounced in patients positive for the T or B cell receptor signalling pathways. Further, pathway PRS-based clustering allowed stratification of patients into four groups with different risk score profiles. Studying sets of genes with priors for involvement in SLE, we observed an aggregate common variant contribution to SLE at genes previously reported for monogenic SLE as well as at interferonopathy genes. CONCLUSIONS: Our results show that pathway risk scores have the potential to stratify patients with SLE beyond clinical manifestations into molecular subsets, which may have implications for clinical follow-up and therapy selection.