Lood et al. find that neutrophil TLR7/8 activation shifts neutrophils from phagocytosis of immune complexes to NETosis. Reduced phagocytosis of immune complexes is associated with partial proteolytic cleavage of FcgRIIA. Cleaved FcgRIIA is found in SLE neutrophils ex vivo.

ObjectivesTo investigate associations between a high genetic disease risk and disease severity in patients with systemic lupus erythematosus (SLE).MethodsPatients with SLE (n=1001, discovery cohort and n=5524, replication cohort) and healthy controls (n=2802 and n=9859) were genotyped using a 200K Immunochip single nucleotide polymorphism array. A genetic risk score (GRS) was assigned to each individual based on 57 SLE risk loci.ResultsSLE was more prevalent in the high, compared with the low, GRS-quartile (OR 12.32 (9.53 to 15.71), p=7.9×10–86 and OR 7.48 (6.73 to 8.32), p=2.2×10–304 for the discovery and the replication cohorts, respectively). In the discovery cohort, patients in the high GRS-quartile had a 6-year earlier mean disease onset (HR 1.47 (1.22 to 1.75), p=4.3×10–5), displayed higher prevalence of damage accrual (OR 1.47 (1.06 to 2.04), p=2.0×10–2), renal disorder (OR 2.22 (1.50 to 3.27), p=5.9×10–5), anti-dsDNA (OR 1.83 (1.19 to 2.81), p=6.1×10–3), end-stage renal disease (ESRD) (OR 5.58 (1.50 to 20.79), p=1.0×10–2), proliferative nephritis (OR 2.42 (1.30 to 4.49), p=5.1×10–3), anti-cardiolipin-IgG (OR 1.89 (1.13 to 3.18), p=1.6×10–2), anti-β2-glycoprotein-I-IgG (OR 2.29 (1.29 to 4.06), p=4.8×10–3) and positive lupus anticoagulant test (OR 2.12 (1.16 to 3.89), p=1.5×10–2) compared with patients in the low GRS-quartile. Survival analysis showed earlier onset of the first organ damage (HR 1.51 (1.04 to 2.25), p=3.7×10–2), first cardiovascular event (HR 1.65 (1.03 to 2.64), p=2.6×10–2), nephritis (HR 2.53 (1.72 to 3.71), p=9.6×10–7), ESRD (HR 6.78 (1.78 to 26.86), p=6.5×10–3) and decreased overall survival (HR 1.83 (1.02 to 3.30), p=4.3×10–2) in high to low quartile comparison.ConclusionsA high GRS is associated with increased risk of organ damage, renal dysfunction and all-cause mortality. Our results indicate that genetic profiling may be useful for predicting outcomes in patients with SLE.

The role of the skin microbiota in human health is poorly understood. Here, we identified and characterized a novel antioxidant enzyme produced by the skin microbiota, designated RoxP for radical oxygenase of Propionibacterium acnes. RoxP is uniquely produced by the predominant skin bacterium P. acnes, with no homologs in other bacteria; it is highly expressed and strongly secreted into culture supernatants. We show that RoxP binds heme, reduces free radicals, and can protect molecules from oxidation. Strikingly, RoxP is crucial for the survival of P. acnes in oxic conditions and for skin colonization of P. acnes ex vivo. Taken together, our study strongly suggests that RoxP facilitates P. acnes’ survival on human skin, and is an important beneficial factor for the host-commensal interaction. Thus, RoxP is the first described skin microbiota-derived mutualistic factor that potentially can be exploited for human skin protection.

Systemic lupus erythematosus (SLE) and antiphospholipid syndrome (APS) are two autoimmune diseases that can occur together or separately. Insights into the pathogenesis have revealed similarities, such as development of autoantibodies targeting subcellular antigens as well as a shared increased risk of cardiovascular morbidity, potentially due to mutual pathologic mechanisms. In this review, we will address the evidence implicating neutrophils in the pathogenesis of these conditions, highlighting their shared features. The neutrophil is the most abundant leukocyte, recognized for its role in infectious and inflammatory diseases, but dysregulation of neutrophil effector functions, including phagocytosis, oxidative burst and formation of neutrophil extracellular traps (NETs) may also contribute to an autoimmune process. The phenotype of neutrophils in SLE and APS differs from neutrophils of healthy individuals, where neutrophils in SLE and APS are activated and prone to aggregate. A specific subset of low-density neutrophils with different function compared to normal-density neutrophils can also be found within the peripheral blood mononuclear cell (PBMC) fraction after density gradient centrifugation of whole blood. Neutrophil phagocytosis is required for regular clearance of cell remnants and nuclear material. Reactive oxygen species (ROS) released by neutrophils during oxidative burst are important for immune suppression and impairment of ROS production is seen in SLE. NETs mediate pathology in both SLE and APS via several mechanisms, including exposure of autoantigens, priming of T-cells and activation of autoreactive B-cells. NETs are also involved in cardiovascular events by forming a pro-thrombotic scaffolding surface. Lastly, neutrophils communicate with other cells by producing cytokines, such as Interferon (IFN) -α, and via direct cell-cell contact. Physiological neutrophil effector functions are necessary to prevent autoimmunity, but in SLE and APS these are altered.

​ObjectivesA single nucleotide polymorphism in the NCF1 gene (NCF1-339, rs201802880), encoding NADPH oxidase type II subunit NCF1/p47phox, reducing production of reactive oxygen species (ROS) is strongly associated with the development of systemic lupus erythematosus (SLE). This study aimed at characterising NCF1-339 effects on neutrophil extracellular trap (NET) formation, type I interferon activity and antibody profile in patients with SLE.​MethodsNeutrophil NET-release pathways (n=31), serum interferon (n=141) and finally antibody profiles (n=305) were investigated in SLE subjects from Lund, genotyped for NCF1-339. Then, 1087 SLE subjects from the rheumatology departments of four Swedish SLE centres, genotyped for NCF1-339, were clinically characterised to validate these findings.​ResultsCompared with patients with normal-ROS NCF1-339 genotypes, neutrophils from patients with SLE with low-ROS NCF1-339 genotypes displayed impaired NET formation (p<0.01) and increased dependence on mitochondrial ROS (p<0.05). Low-ROS patients also had increased frequency of high serum interferon activity (80% vs 21.4%, p<0.05) and positivity for anti-β2 glycoprotein I (p<0.01) and anticardiolipin antibodies (p<0.05) but were not associated with other antibodies. We confirmed an over-representation of having any antiphospholipid antibody, OR 1.40 (95% CI 1.01 to 1.95), anti-β2 glycoprotein I, OR 1.82 (95% CI 1.02 to 3.24) and the antiphospholipid syndrome (APS), OR 1.74 (95% CI 1.19 to 2.55) in all four cohorts (n=1087).​ConclusionsThe NCF1-339 SNP mediated decreased NADPH oxidase function, is associated with high interferon activity and impaired formation of NETs in SLE, allowing dependence on mitochondrial ROS. Unexpectedly, we revealed a striking connection between the ROS deficient NCF1-339 genotypes and the presence of phospholipid antibodies and APS.