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IntroductionA recent metabolomic screen of sera from patients with Systemic Lupus Erythematosus (SLE) found reduction of antioxidants and substrates for energy generation. These metabolic alterations may underlie one of the most common features of SLE - fatigue. The metabolomic studies also noted reduced omega-3 fatty acids, which are powerful anti- oxidants. This deficiency may be causally related to oxidative stress, inflammation, disease activity, and fatigue in SLE. Supplementation of omega-3 fatty acids using fish oil in SLE has been shown to reduce oxidative stress in other studies. The objective of this study is to evaluate the effect of fish oil supplementation on clinical measures of fatigue, quality of life, and disease activity as part of a randomized clinical trial.MethodsFifty SLE patients recruited in outpatient clinics were randomized 1:1 to fish oil supplementation or olive oil placebo, and blinded to their treatment group. At baseline and after 6 months of treatment, RAND Short Form-36 (RAND SF-36), Fatigue Severity Scale (FSS), SLE Disease Activity Index (SLEDAI), and Physician Global Assessment (PGA) were completed; serum was also collected for soluble mediator analysis.ResultsThirty-two patients completed the study. PGA improved significantly in the fish oil group compared with the placebo group (p = 0.015). The RAND SF-36 Energy/fatigue and Emotional well-being scores demonstrated improvement trends (p = 0.092 and 0.070). No clear difference was seen in FSS and SLEDAI (p = 0.350 and p = 0.417). Erythrocyte sedimentation rate and serum IL-12 were reduced (p = 0.008 and p = 0.058); while serum IL-13 was increased by fish oil supplementation (p = 0.033).ConclusionsIn this randomized, placebo-controlled 6-month trial, SLE patients randomized to fish oil supplementation demonstrated improvement in their PGA, RAND SF-36, and some circulating inflammatory markers.Trial registrationClinicalTrials.gov Identifier: NCT02021513 (registered 13 December 2013).

A B S T R A C TBackground: The clinical and pathologic diversity of systemic lupus erythematosus (SLE) hinders diagnosis, management, and treatment development. This study addresses heterogeneity in SLE through comprehensive molecular phenotyping and machine learning clustering. Methods: Adult SLE patients (n = 198) provided plasma, serum, and RNA. Disease activity was scored by modified SELENA-SLEDAI. Twenty-nine co-expression module scores were calculated from microarray geneexpression data. Plasma soluble mediators (n = 23) and autoantibodies (n = 13) were assessed by multiplex bead-based assays and ELISAs. Patient clusters were identified by machine learning combining K-means clustering and random forest analysis of co-expression module scores and soluble mediators. Findings: SLEDAI scores correlated with interferon, plasma cell, and select cell cycle modules, and with circulating IFN-a, IP10, and IL-1a levels. Co-expression modules and soluble mediators differentiated seven clusters of SLE patients with unique molecular phenotypes. Inflammation and interferon modules were elevated in Clusters 1 (moderately) and 4 (strongly), with decreased T cell modules in Cluster 4. Monocyte, neutrophil, plasmablast, B cell, and T cell modules distinguished the remaining clusters. Active clinical features were similar across clusters. Clinical SLEDAI trended highest in Clusters 3 and 4, though Cluster 3 lacked strong interferon and inflammation signatures. Renal activity was more frequent in Cluster 4, and rare in Clusters 2, 5, and 7. Serology findings were lowest in Clusters 2 and 5. Musculoskeletal and mucocutaneous activity were common in all clusters. Interpretation: Molecular profiles distinguish SLE subsets that are not apparent from clinical information. Prospective longitudinal studies of these profiles may help improve prognostic evaluation, clinical trial design, and precision medicine approaches.

SLE, a multisystem heterogeneous disease, is characterized by production of antibodies to cellular components, with activation of both the innate and the adaptive immune system. Decades of investigation of blood biomarkers has resulted in incremental improvements in the understanding of SLE. Owing to the heterogeneity of immune dysregulation, no single biomarker has emerged as a surrogate for disease activity or prediction of disease. Beyond identification of surrogate biomarkers, a multitude of clinical trials have sought to inhibit elevated SLE biomarkers for therapeutic benefit. Armed with new -omics technologies, the necessary yet daunting quest to identify better surrogate biomarkers and successful therapeutics for SLE continues with tenacity.

Systemic lupus erythematosus (SLE) is characterized by antibody-mediated chronic inflammation in the kidney, lung, skin, and other organs to cause inflammation and damage. Several inflammatory pathways are dysregulated in SLE, and understanding these pathways may improve diagnosis and treatment. In one such pathway, Axl tyrosine kinase receptor responds to Gas6 ligand to block inflammation in leukocytes. A soluble form of the Axl receptor ectodomain (sAxl) is elevated in serum from patients with SLE and lupus-prone mice. We hypothesized that sAxl in SLE serum originates from the surface of leukocytes and that the loss of leukocyte Axl contributes to the disease. We determined that macrophages and B cells are a source of sAxl in SLE and in lupus-prone mice. Shedding of the Axl ectodomain from the leukocytes of lupus-prone mice is mediated by the matrix metalloproteases ADAM10 and TACE (ADAM17). Loss of Axl from lupus-prone macrophages renders them unresponsive to Gas6-induced anti-inflammatory signaling in vitro. This phenotype is rescued by combined ADAM10/TACE inhibition. Mice with Axl-deficient macrophages develop worse disease than controls when challenged with anti-glomerular basement membrane (anti-GBM) sera in an induced model of nephritis. ADAM10 and TACE also mediate human SLE PBMC Axl cleavage. Collectively, these studies indicate that increased metalloprotease-mediated cleavage of leukocyte Axl may contribute to end organ disease in lupus. They further suggest dual ADAM10/TACE inhibition as a potential therapeutic modality in SLE.