SMART-SLE: serology monitoring and repeat testing in systemic lupus erythematosus-an analysis of anti-double-stranded DNA monitoring.

OBJECTIVE: Disease activity monitoring in SLE includes serial measurement of anti-double stranded-DNA (dsDNA) antibodies, but in patients who are persistently anti-dsDNA positive, the utility of repeated measurement is unclear. We investigated the usefulness of serial anti-dsDNA testing in predicting flare in SLE patients who are persistently anti-dsDNA positive. METHODS: Data were analysed from patients in a multinational longitudinal cohort with known anti-dsDNA results from 2013 to 2021. Patients were categorized based on their anti-dsDNA results as persistently negative, fluctuating or persistently positive. Cox regression models were used to examine longitudinal associations of anti-dsDNA results with flare. RESULTS: Data from 37 582 visits of 3484 patients were analysed. Of the patients 1029 (29.5%) had persistently positive anti-dsDNA and 1195 (34.3%) had fluctuating results. Anti-dsDNA expressed as a ratio to the normal cut-off was associated with the risk of subsequent flare, including in the persistently positive cohort (adjusted hazard ratio [HR] 1.56; 95% CI: 1.30, 1.87; P < 0.001) and fluctuating cohort (adjusted HR 1.46; 95% CI: 1.28, 1.66), both for a ratio >3. Both increases and decreases in anti-dsDNA more than 2-fold compared with the previous visit were associated with increased risk of flare in the fluctuating cohort (adjusted HR 1.33; 95% CI: 1.08, 1.65; P = 0.008) and the persistently positive cohort (adjusted HR 1.36; 95% CI: 1.08, 1.71; P = 0.009). CONCLUSION: Absolute value and change in anti-dsDNA titres predict flares, including in persistently anti-dsDNA positive patients. This indicates that repeat monitoring of dsDNA has value in routine testing.

The performance of different classification criteria for systemic lupus erythematosus in a real-world rheumatology department.

OBJECTIVE: New classification criteria have been proposed to improve classification of systemic lupus erythematosus (SLE). We aimed to evaluate their performance by determining their sensitivity, specificity and accuracy in a real-world rheumatology department. METHODS: SLE patients who were enrolled in the Australian Lupus Registry and Biobank were included and compared with controls recruited from other rheumatology clinics. Clinical and immunological features were reviewed, according to ACR 1997, SLICC 2012, EULAR/ACR 2019, or Systemic Lupus Erythematosus Risk Probability Index (SLERPI). Performance of each set of criteria was evaluated for the overall cohort and in a subgroup of patients with early SLE. RESULTS: The study included 394 SLE and 123 control patients with other rheumatological conditions. Sensitivity was highest using SLICC 2012 or SLERPI 2020 criteria. Specificity was highest using ACR 1997 criteria. The SLICC 2012 criteria had the highest overall accuracy at 94.4% (95% CI: 91.7, 97.1%). In the subgroup analysis of SLE patients with early disease, SLICC 2012 performed similarly well. CONCLUSIONS: The sensitivity and specificity of each set of classification criteria vary slightly, with SLICC 2012 and SLERPI 2020 having the highest sensitivities and the ACR 1997 criteria having the highest specificity in our patient cohort. All classification criteria serve as good instructional aids for clinicians to understand SLE manifestations. For the Australian Lupus Registry and Biobank, we will continue to use the ACR 1997 and/or SLICC 2012 as entry to the observational cohort.

Algorithm for calculating high disease activity in SLE.

BACKGROUND: The ability to identify lupus patients in high disease activity status (HDAS) without knowledge of the SLEDAI could have application in selection of patients for treatment escalation or enrolment in trials. We sought to generate an algorithm that could calculate via model fitting the presence of HDAS using simple demographic and laboratory values. METHODS: We examined the association of high disease activity (HDA) with demographic and laboratory parameters using prospectively collected data. An HDA visit is recorded when SLEDAI-2K ≥10. We utilized the use of combinatorial search to find algorithms to build a mathematical model predictive of HDA. Performance of each algorithm was evaluated using multi-class area under the receiver operating characteristic curve and the final model was compared with the naïve Bayes classifier, and analysed using the confusion matrix for accuracy and misclassification rate. RESULTS: Data on 286 patients, followed for a median of 5.1 years were studied for a total of 5680 visits. Sixteen laboratory parameters were found to be significantly associated with HDA. A total of 216 algorithms were evaluated and the final algorithm chosen was based on seven pathology measures and three demographic variables. It has an accuracy of 88.6% and misclassification rate of 11.4%. When compared with the naïve Bayes classifier [area under the curve (AUC) = 0.663], our algorithm has a better accuracy with AUC = 0.829. CONCLUSION: This study shows that building an accurate model to calculate HDA using routinely available clinical parameters is feasible. Future studies to independently validate the algorithm will be needed to confirm its predictive performance.

Diabetes in young adult men: social and health-related correlates.

BACKGROUND: Diabetes is a global public health issue. It is associated with significant disability, morbidity and mortality risks and substantial healthcare costs. Of great concern is the fact that its prevalence is rising, particularly amongst the young, while epidemiological data regarding the incidence, prevalence and complications of early-onset type 2 diabetes is noted to be sparse. METHODS: We used data from the baseline wave of Ten to Men, a national cohort study of Australian males, to investigate the social and health-related correlates of Australian males aged 18-49 years reporting being diagnosed with diabetes. RESULTS: The estimated prevalence of a self-reported diabetes diagnosis amongst Australian males aged 18-49 years was 2.95 % (95 % CI: 2.54-3.43 %). Within this age group, approximately 75 % of those diagnosed with diabetes are expected to be living with a known diagnosis of type 2 diabetes; the remainder are expected to be living with type 1 diabetes. Of the 20 social and health-related factors considered, we found evidence to support the association of eighteen factors after adjusting for age and body mass index. The strongest correlates of reporting a diabetes diagnosis, associated with a ≥2-fold increase in the odds of reporting diabetes were being aged 35-49 years, being unemployed, being obese, seeing a doctor for a check-up more frequently, reporting comorbid high blood pressure or physical or mental health comorbidities and worse self-rated and physical health status. CONCLUSION: Australian males aged 18-49 years who are living with a known diagnosis of diabetes are more likely to be socio-economically disadvantaged and suffer substantially worse health status than Australian males aged 18-49 years living without a diabetes diagnosis. Based on the associations detected in this study, older, single males living in regional areas who are socioeconomically disadvantaged, obese and/or who have other comorbidities may be an important subgroup to target for diabetes screening, disease management and prevention efforts.

The Australian longitudinal study on male health-methods.

BACKGROUND: The Australian Longitudinal Study on Male Health (Ten to Men) was established in 2011 to build the evidence base on male health to inform policy and program development. METHODS: Ten to Men is a national longitudinal study with a stratified multi-stage cluster random sample design and oversampling in rural and regional areas. Household recruitment was conducted from October 2013 to July 2014. Males who were aged 10 to 55 years residing in private dwellings were eligible to participate. Data were collected via self-completion paper questionnaires (participants aged 15 to 55) and by computer-assisted personal interview (boys aged 10 to 14). Household and proxy health data for boys were collected from a parent via a self-completion paper-based questionnaire. Questions covered socio-demographics, health status, mental health and wellbeing, health behaviours, social determinants, and health knowledge and service use. RESULTS: A cohort of 15,988 males aged between 10 and 55 years was recruited representing a response fraction of 35 %. CONCLUSION: Ten to Men is a unique resource for investigating male health and wellbeing. Wave 1 data are available for approved research projects.

Age Matters: Exploring Correlates of Self-Rated Health Across Four Generations of Australian Males.

The importance of addressing health disparities experienced by boys and men reached tangible prominence in Australia with adoption of the 2010 National Male Health Policy and the establishment of a national longitudinal study on male health-Ten to Men. Ten to Men is based on a holistic model of health with a strong focus on social determinants and health and well-being over the life course. Given the life course focus, we set out to assess if health-related characteristics and the correlates of self-rated health differ across the life course among four sociologically defined generations of Australian males. While some differences in the correlates of good or excellent health were observed across generations, addressing obesity and depression appear to be important for improving the health of Australian males of all ages.

Association of social determinants of health with self-rated health among Australian gay and bisexual men living with HIV.

Despite a vast improvement in the survival of people living with HIV (PLHIV) since the introduction of combination antiretroviral treatment (cART), little change in the self-rated health of PLHIV has been observed since the introduction of cART in Australia. Difficulties with attaining employment or achieving financial security have been noted as some of the key challenges still facing PLHIV in the post-cART era. As a result, we investigated the independent association of a number of key social determinants of health with self-rated health among HIV-positive gay and bisexual men in Australia. Data from two recent national, cross-sectional surveys of PLHIV (the HIV Futures 5 and 6 surveys) were used. Logistic regression was used to assess the independent association of ethnicity, region of residence, education level, employment status, after-tax income, experience of HIV-related discrimination, level of social support, relationship status and recent sexual activity with reporting good-excellent self-rated health, after adjusting for clinical factors and other social determinants of health. Multiple imputation was used to estimate missing data for variables with >5% missing data. Of the 1713 HIV-positive gay/bisexual men who responded to the HIV Futures 5 and 6 surveys, information on self-rated health was available for 99.3%. Close to three-quarters of these respondents (72.1%) reported their self-rated health as good or excellent; the remainder (27.9%) reported their self-rated health as poor or fair. In multivariable analysis involving 89.3% of respondents, being employed, reporting recent sexual activity, a greater number of sources of social support and a higher weekly after-tax income were found to be independently associated with reporting good-excellent self-rated health. Despite the inability of this study to detect causal associations, addressing barriers to employment and sexual activity, and mechanisms to increase social support, is likely to have positive health effects for PLHIV in Australia.

Smith-specific regulatory T cells halt the progression of lupus nephritis.

Antigen-specific regulatory T cells (Tregs) suppress pathogenic autoreactivity and are potential therapeutic candidates for autoimmune diseases such as systemic lupus erythematosus (SLE). Lupus nephritis is associated with autoreactivity to the Smith (Sm) autoantigen and the human leucocyte antigen (HLA)-DR15 haplotype; hence, we investigated the potential of Sm-specific Tregs (Sm-Tregs) to suppress disease. Here we identify a HLA-DR15 restricted immunodominant Sm T cell epitope using biophysical affinity binding assays, then identify high-affinity Sm-specific T cell receptors (TCRs) using high-throughput single-cell sequencing. Using lentiviral vectors, we transduce our lead Sm-specific TCR into Tregs derived from patients with SLE who are anti-Sm and HLA-DR15 positive. Compared with polyclonal mock-transduced Tregs, Sm-Tregs potently suppress Sm-specific pro-inflammatory responses in vitro and suppress disease progression in a humanized mouse model of lupus nephritis. These results show that Sm-Tregs are a promising therapy for SLE.

Towards a novel clinical outcome assessment for systemic lupus erythematosus: first outcomes of an international taskforce.

Systemic lupus erythematosus (SLE) is a disease of high unmet therapeutic need. The challenge of accurately measuring clinically meaningful responses to treatment has hindered progress towards positive outcomes in SLE trials, impeding the approval of potential new therapies. Current primary end points used in SLE trials are based on legacy disease activity measures that were neither specifically designed for the clinical trial context, nor developed according to contemporary recommendations for clinical outcome assessments (COAs), such as that substantial patient input should be incorporated into their design. The Treatment Response Measure for SLE (TRM-SLE) Taskforce is a global collaboration of SLE clinician-academics, patients and patient representatives, industry partners and regulatory experts, established to realize the goal of developing a new COA for SLE clinical trials. The aim of this project is a novel COA designed specifically to measure treatment effects that are clinically meaningful to patients and clinicians, and intended for implementation in a trial end point that supports regulatory approval of novel therapeutic agents in SLE. This Consensus Statement reports the first outcomes of the TRM-SLE project, including a structured process for TRM-SLE development.

Type 1 interferon status in systemic lupus erythematosus: a longitudinal analysis.

OBJECTIVES: Type 1 interferon (IFN) is key to the pathogenesis of SLE, evidenced by the expression of IFN-stimulated genes (ISGs) in most patients, but the clinical utility of serial ISG assessment remains unknown. With the emergence of IFN-blocking drugs, we aimed to examine IFN status in relation to clinical findings longitudinally to provide insights into the value of testing ISG levels over time. METHODS: Clinical data and whole blood were collected prospectively on adult patients with SLE from a single tertiary lupus centre. IFN status was measured using a panel of ISGs. FINDINGS: 729 samples were analysed from 205 patients. At baseline, 62.9% of patients were IFN high, 30.2% IFN low and 6.8% borderline. 142 patients had multiple samples collected, and 87.3% of these demonstrated stable ISG status over time. In longitudinal follow-up, IFN high patients had higher activity in multiple organ domains and spent less time in Lupus Low Disease Activity State, but IFN score did not correlate with SLE Disease Activity Index in individual patients. In the small subset of patients who had large fluctuations in ISG across the observation period, most had high-dose glucocorticoids that correlated with ISG suppression. However, low-moderate-dose glucocorticoids did not suppress ISG expression. CONCLUSION: Although IFN high status is associated with indicators of more severe SLE, in the majority of patients, ISGs are stable across time and do not correlate with disease activity. Changes in ISG expression may be seen with high-dose, but not routine dose, glucocorticoid exposure. These findings suggest baseline but not serial ISG measurement may be of value in the management of SLE.

Immunosuppressant exposure confounds gene expression analysis in systemic lupus erythematosus.

Objectives: The analysis of gene module expression in SLE is emerging as a tool to identify active biological pathways, with the aim of developing targeted therapies for subsets of patients. Detailed information on the effect of immunosuppressants on gene module expression is lacking. We aimed to examine the impact of medication exposure on gene module expression. Methods: A set of commercially available disease-relevant gene modules were measured in 730 whole blood samples from a dedicated lupus clinic on whom prospectively collected, contemporaneous clinical data including medication exposure were available. Results: Compared to heathy controls, SLE patients showed over-expression of IFN and under-expression of B cell, T cell and pDC modules. Neutrophil module over-expression and under-expression of B and T cell modules were observed in patients with active lupus nephritis or highly active disease (SLEDAI-2K > 8), while Lupus Low Disease Activity State (LLDAS) had inverse associations. Disease activity in other organ domains was not associated with specific gene modules. In contrast, medications were associated with multiple effects. Glucocorticoid use was associated with under-expression of T cell, B cell and plasmablast modules, and over-expression of neutrophil modules. Mycophenolate and azathioprine exposure were associated with plasmablast module and B cell module under-expression respectively. Disease activity associations with neutrophil over-expression and lymphocyte module under-expression were attenuated by multivariable adjustment for medication exposure. Conclusion: Medications have significant effect on gene module expression in SLE patients. These findings emphasize the need to control for medications in studies of gene expression in SLE.

Predictors of infection requiring hospitalization in patients with systemic lupus erythematosus: a time-to-event analysis.

OBJECTIVES: To evaluate the predictors of serious infection in patients with systemic lupus erythematosus (SLE). METHODS: Serious infections were identified in SLE patients in a prospectively-followed single centre cohort. Associations of serious infection with disease-related variables and medication use were analysed using Cox and related regression models. RESULTS: 346 patients were followed for a mean (SD) of 6.6 (3.7) years. 86 episodes of serious infection were observed, with an incidence rate of 3.8 episodes per 100 person-years. Patients who had serious infection had higher baseline SLE Damage Index (SDI) and Charlston Comorbidity Index (CCI); they were also more likely to have high disease activity status (HDAS), and higher disease activity in multiple clinical domains, higher flare rates, higher time-adjusted prednisolone dose exposure, and less time in lupus low disease activity state (LLDAS). Patients who have received cyclophosphamide, rituximab and mycophenolate were more likely to have experienced serious infection. After multivariable adjustment in Cox regression analysis, cyclophosphamide, higher SDI score, and higher disease activity were associated with an increased hazard of first serious infection. History of previous serious infection conferred the highest risk. Lymphopenia was also a modest but statistically significant predictor of serious infection. CONCLUSION: History of previous serious infection was the strongest predictor of serious infection in our SLE cohort. This study also suggests that clinical factors such as damage accrual, disease activity, and choice of immunosuppressant, can each have an independent risk in predicting serious infection particularly the first episode.

Disease course following High Disease Activity Status revealed patterns in SLE.

BACKGROUND: We sought to examine the disease course of High Disease Activity Status (HDAS) patients and their different disease patterns in a real-world longitudinal cohort. Disease resolution till Lupus Low Disease Activity State (LLDAS) has been a general treatment goal, but there is limited information on this subset of patients who achieve this. METHODS: All consenting patients of the Monash Lupus Cohort who had at least 12 months of observation were included. HDAS was defined as SLEDAI-2K ≥ 10 ever, and HDAS episode as the period from the first HDAS clinic visit until attainment of LLDAS. We examined the associations of different HDAS patterns with the likelihood of damage accrual. RESULTS: Of 342 SLE patients, 151 experienced HDAS at least once, accounting for 298 HDAS episodes. The majority of HDAS patients (76.2%) experienced Recurrent HDAS (> 1 HDAS visit), and a smaller subset (47.7%) had Persistent HDAS (consecutive HDAS visits for longer than 2 months). Recurrent or Persistent HDAS patients were younger at diagnosis and more likely to experience renal or serositis manifestations; persistent HDAS patients were also more likely to experience neurological manifestations. Baseline SLEDAI greater than 10 was associated with longer HDAS episodes. Recurrent and Persistent HDAS were both associated with an increased likelihood of damage accrual. The total duration of HDAS episode greater than 2 years and experiencing multiple HDAS episodes (≥4) was also associated with an increased likelihood of damage accrual (OR 1.80, 95% CI 1.08-2.97, p = 0.02, and OR 3.31, 95% CI 1.66-13.26, p = 0.01, respectively). CONCLUSION: HDAS episodes have a highly variable course. Recurrent and Persistent HDAS, and longer duration of HDAS episodes, increased the risk of damage accrual. In addition to a major signifier of severity in SLE, its resolution to LLDAS can determine the subsequent outcome in SLE patients.

Impact of early dose intensity on cytogenetic and molecular responses in chronic- phase CML patients receiving 600 mg/day of imatinib as initial therapy.

We conducted a trial in 103 patients with newly diagnosed chronic phase chronic myeloid leukemia (CP-CML) using imatinib 600 mg/day, with dose escalation to 800 mg/day for suboptimal response. The estimated cumulative incidences of complete cytogenetic response (CCR) by 12 and 24 months were 88% and 90%, and major molecular responses (MMRs) were 47% and 73%. In patients who maintained a daily average of 600 mg of imatinib for the first 6 months (n = 60), MMR rates by 12 and 24 months were 55% and 77% compared with 32% and 53% in patients averaging less than 600 mg (P = .037 and .016, respectively). Dose escalation was indicated for 17 patients before 12 months for failure to achieve, or maintain, major cytogenetic response at 6 months or CCR at 9 months but was only possible in 8 patients (47%). Dose escalation was indicated for 73 patients after 12 months because their BCR-ABL level remained more than 0.01% (international scale) and was possible in 45 of 73 (62%). Superior responses achieved in patients able to tolerate imatinib at 600 mg suggests that early dose intensity may be critical to optimize response in CP-CML. The trial was registered at www.ANZCTR.org.au as #ACTRN12607000614493.

High disease activity status suggests more severe disease and damage accrual in systemic lupus erythematosus.

OBJECTIVE: Disease severity in SLE is an important concept related to disease activity, treatment burden and prognosis. We set out to evaluate if high disease activity status (HDAS), based on ever attainment of a Systemic Lupus Erythematosus Disease Activity Index (SLEDAI) disease activity score of ≥10, is an indicator for disease severity in SLE. METHODS: Using prospectively collected data, we assessed the association of HDAS with sociodemographic and disease characteristics and adverse clinical outcomes using logistic regression or generalised estimating equations. RESULTS: Of 286 patients with SLE, who were observed for a median (range) of 5.1 years (1-10.8 years), 43.7% experienced HDAS at least once during the observational period. Autoantibody positivity, particularly anti-dsDNA and anti-Sm positivity, were associated with increased likelihood of HDAS. Age ≥45 years at diagnosis was associated with reduced likelihood of HDAS (p=0.002). Patients with HDAS had higher Physician Global Assessment score (>1: OR 8.1, p<0.001) and were more likely to meet criteria for flare (mild/moderate flare: OR 4.4, p<0.001; severe flare: OR 17.2, p<0.001) at the time of experiencing HDAS. They were also more likely to have overall higher disease activity, as defined by time-adjusted mean SLEDAI-2K score in the highest quartile (OR 11.7, 95% CI 5.1 to 26.6; p>0.001), higher corticosteroid exposure (corticosteroid dose in highest quartile: OR 7.7, 95% CI 3.9 to 15.3; p<0.001) and damage accrual (OR 2.3, 95% CI 1.3 to 3.9; p=0.003) when compared with non-HDAS patients. CONCLUSIONS: HDAS is associated with more severe disease, as measured by higher disease activity across time, corticosteroid exposure and damage accrual. The occurrence of HDAS may be a useful prognostic marker in the management of SLE.

Associations of serum soluble Fas and Fas ligand (FasL) with outcomes in systemic lupus erythematosus.

OBJECTIVE: Fas/Fas ligand (FasL) and B cell-activating factor (BAFF) signalling have pivotal roles in SLE pathogenesis. We investigated the clinical associations of serum concentrations of soluble Fas (sFas) and soluble FasL (sFasL) in SLE and their relationship with BAFF. METHODS: Serum sFas and sFasL were quantified by multiplex assay, and BAFF by ELISA, in 118 patients with SLE and 17 healthy controls (HC). SLE disease activity and organ damage were assessed using the Systemic Lupus Erythematosus Disease Activity Index 2000 (SLEDAI-2K) and the Systemic Lupus International Collaborating Clinics Damage Index. RESULTS: sFas, sFasL and BAFF were detectable in all samples. Serum sFas and sFasL were significantly higher in SLE compared with HC. In univariable regression analyses, patients with active renal disease and those with flare had significantly higher levels of sFas compared with those without. High serum BAFF in patients with SLE was associated with increased sFas but not sFasL. The association between sFas and renal disease remained significant after adjusting for BAFF, but the association with flare attenuated. High sFas levels were associated with increased time-adjusted mean SLEDAI-2K, even after adjusting for BAFF, and with higher odds of flare over time. In contrast, high sFasL was associated with reduced organ damage over time. Serum sFasL/sFas ratio was negatively associated with active overall disease, flare and organ damage. CONCLUSIONS: Serum sFas is associated with active renal SLE, and active disease and flare over time, while sFasL/sFas ratio is negatively associated with disease activity and organ damage accrual. Treatments correcting abnormal levels of sFas/FasL may be worthy of evaluation in SLE.

Lupus Low Disease Activity State and Reduced Direct Health Care Costs in Patients With Systemic Lupus Erythematosus.

OBJECTIVE: Treat-to-target end points for systemic lupus erythematosus (SLE) have been assessed for their impact on damage accrual and flare, but whether they have an impact on the high health care utilization and costs in SLE has not been studied. The purpose of this study was to examine our hypothesis that the recently described lupus low disease activity state (LLDAS) would be associated with reduced health care cost. METHODS: Data from a single tertiary hospital longitudinal SLE cohort were assessed. Baseline demographics, disease activity (Systemic Lupus Erythematosus Disease Activity Index 2000 [SLEDAI-2K], physician global assessment [PhGA], and flare index), and medication use were evaluated, and direct health care utilization and cost data were obtained from hospital information systems. LLDAS was defined as previously published: briefly, SLEDAI-2K ≤4 with no new activity, PhGA ≤1, prednisolone ≤7.5 mg/day, and optimal standard immunosuppressive agents. Analysis was performed using multivariable linear regression. RESULTS: Two hundred SLE patients, contributing 357.8 person-years of observation, were included. A history of lupus nephritis was present in 42% of patients, and damage (Systemic Lupus International Collaborating Clinics/American College of Rheumatology Damage Index >0) was present at study commencement in 57.3% of patients. The mean ± SD annual direct medical cost per patient was US$7,413 ± 13,133/year. In multivariable analysis, increased cost was associated with the presence of baseline organ damage (41.7% increase; P = 0.009) and corticosteroid use (>7.5-15 mg/day: 55.7% increase; P = 0.02; and >15 mg/day: 202% increase; P < 0.001). In contrast, spending ≥50% of the observation period in LLDAS was associated with a 25.9% reduction in annual direct medical cost (P = 0.04). CONCLUSION: Greater time spent in LLDAS was associated with significantly reduced direct hospital health care costs among patients with SLE.

Novel Methods of Incorporating Time in Longitudinal Multivariate Analysis Reveals Hidden Associations With Disease Activity in Systemic Lupus Erythematosus.

Objective: Systemic lupus erythematosus (SLE) is a multisystem autoimmune disease. SLE is characterized by high inter-patient variability, including fluctuations over time, a factor which most biomarker studies omit from consideration. We investigated relationships between disease activity and biomarker expression in SLE, using novel methods to control for time-dependent variability, in a proof-of-concept study to evaluate whether doing so revealed additional information. Methods: We measured 4 serum biomarkers (MIF, CCL2, CCL19, and CXCL10) and 13 routine clinical laboratory parameters, alongside disease activity measured by the SLE disease activity index-2k (SLEDAI-2k), collected longitudinally. We analyzed these data with unsupervised learning methods via ensemble clustering, incorporating temporal relationships using dynamic time warping for distance metric calculation. Results: Data from 843 visits in 110 patients (median age 47, 83% female) demonstrated highly heterogeneous time-dependent relationships between disease activity and biomarkers. Unbiased magnitude-based hierarchical clustering of biomarker expression levels isolated a patient subset (n = 9) with distinctively heterogeneous expression of the 17 biological parameters, and who had MIF, CCL2, CCL19, and CXCL10 levels that were higher and more strongly associated with disease activity, based on leave-one-out cross-validated regression analysis. In the remaining subgroup, a time-dependent regression model revealed significantly stronger predictive power of biomarkers for disease activity, compared to a time-agnostic regression model. Despite no significant difference in simple magnitude, using dynamic time warping analysis to align longitudinal profiles revealed a large subset (n = 69) with significantly stronger associations between biological parameters and disease activity. This subgroup had significantly lower flare rates, disease activity and damage scores, suggesting this clustering is clinically meaningful. Conclusions: These results suggest associations between biological parameters and disease activity in SLE exist in a multi-dimensional time-dependent pattern, with implications for the analysis of biomarkers in SLE often used to identify therapeutic targets. Novel methods to analyse high-dimensional data and control for time-dependent variability may have broad utility in the study complex relationships between clinical and biological parameters.

Analysis of serum B cell-activating factor from the tumor necrosis factor family (BAFF) and its soluble receptors in systemic lupus erythematosus.

OBJECTIVES: To determine the presence and clinical associations of the soluble receptors of B cell-activating factor from the tumor necrosis factor family (BAFF) in serum of patients with systemic lupus erythematosus (SLE). METHODS: Serum BAFF and soluble BAFF receptor (sBAFF-R) were quantified using ELISA, and soluble B cell maturation antigen (sBCMA) and transmembrane activator and cyclophilin ligand interactor (sTACI) by Luminex, in 87 SLE patients and 17 healthy controls (HC). Disease activity and organ damage were assessed using SLE Disease Activity Index 2000 (SLEDAI-2K) and Systemic Lupus International Collaborating Clinics (SLICC) SLE Damage Index (SDI), respectively. RESULTS: BAFF and all receptors were detectable in all serum samples. Serum sBCMA and sTACI, but not sBAFF-R, were significantly higher in SLE than in HC. Serum BAFF was also increased in SLE, but this association was attenuated after adjusting for age and ethnicity. Increased serum BAFF was associated with flare and organ damage. Increased serum sBCMA was associated with the presence of anti-dsDNA, but not with overall or organ-specific disease activity, flare or organ damage. Neither sTACI nor sBAFF-R was associated with any SLE clinical parameters in multivariable analysis. While serum BAFF correlated negatively with sBAFF-R in HC, no statistically significant correlations were observed between BAFF and its receptors in SLE patients. CONCLUSION: Serum BAFF was associated with flare and organ damage independent of the presence of its soluble receptors. While sBCMA was associated with anti-dsDNA positivity, other soluble BAFF receptors were not associated with SLE clinical indicators.

Analysis of Serum Interleukin (IL)-1ß and IL-18 in Systemic Lupus Erythematosus.

Systemic lupus erythematosus (SLE) is a chronic multisystem autoimmune disease characterized by biological and clinical heterogeneity. The interleukin (IL)-1 superfamily is a group of innate cytokines that contribute to pathogenesis in many autoimmune diseases. IL-1ß and IL-18 are two members that have been shown to play a role in murine lupus-like models, but their role in human SLE remains poorly understood. Here, IL-1ß and IL-18 were quantified by enzyme-linked immunosorbent assay in the serum of healthy controls (HCs) and SLE patients from a prospectively followed cohort. Disease activity and organ damage were assessed using SLE disease activity index 2000 (SLEDAI-2K) and SLE damage index scores (SDI), respectively. 184 SLE patients (mean age 44.9 years, 91% female, 56% double-stranded deoxyribonucleic acid positive) were compared to 52 HC. SLE patients had median [IQR] SLEDAI-2K of 4 [2,6], and SDI of 1 [0-2]. Serum IL-18 levels were statistically significantly higher in SLE patients compared to HCs. Univariable linear regression analyses showed that patients with active renal disease or irreversible organ damage had statistically significantly elevated serum IL-18 levels. The association between serum IL-18 and active renal disease was confirmed in multivariable analysis after adjusting for ethnicity and organ damage. High baseline serum IL-18 levels were associated with organ damage at the subsequent visit. Serum IL-1ß levels were not significantly elevated in SLE patients when compared to HCs and had no association with overall or organ-specific disease activity or organ damage in cross-sectional and longitudinal analyses. Our data suggest that serum IL-18 and IL-1ß have different clinical implications in SLE, with IL-18 being potentially associated with active renal disease.