A Regulatory Feedback between Plasmacytoid Dendritic Cells and Regulatory B Cells Is Aberrant in Systemic Lupus Erythematosus

SummarySignals controlling the generation of regulatory B (Breg) cells remain ill-defined. Here we report an “auto”-regulatory feedback mechanism between plasmacytoid dendritic cells (pDCs) and Breg cells. In healthy individuals, pDCs drive the differentiation of CD19+CD24hiCD38hi (immature) B cells into IL-10-producing CD24+CD38hi Breg cells and plasmablasts, via the release of IFN-α and CD40 engagement. CD24+CD38hi Breg cells conversely restrained IFN-α production by pDCs via IL-10 release. In systemic lupus erythematosus (SLE), this cross-talk was compromised; pDCs promoted plasmablast differentiation but failed to induce Breg cells. This defect was recapitulated in healthy B cells upon exposure to a high concentration of IFN-α. Defective pDC-mediated expansion of CD24+CD38hi Breg cell numbers in SLE was associated with altered STAT1 and STAT3 activation. Both altered pDC-CD24+CD38hi Breg cell interactions and STAT1-STAT3 activation were normalized in SLE patients responding to rituximab. We propose that alteration in pDC-CD24+CD38hi Breg cell interaction contributes to the pathogenesis of SLE

Survival analysis of mortality and development of lupus nephritis in patients with systemic lupus erythematosus up to 40-years of follow-up

OBJECTIVES: Patients with systemic lupus erythematosus (SLE) have increased mortality compared with age and sex-matched controls. Lupus nephritis (LN) is a severe manifestation of SLE and an important cause of death. We carried out a retrospective survival analysis to investigate factors that could influence risk of mortality and LN in a large multi-ethnic cohort of patients with SLE. METHODS: By careful review of medical records, we identified 496 patients with SLE for whom we had complete information regarding period of observation and occurrence of death and nephritis. Patients were stratified into groups according to sex, ethnicity, age at start of follow-up and time-period of diagnosis. Kaplan-Meier analysis was used to investigate differences between the groups. RESULTS: Of 496 patients in the study, 91(18.3%) died, 165(33.3%) developed LN and 33(6.7%) developed end-stage renal failure. There was no difference between men and women in either mortality or development of LN. Caucasian patients were significantly less likely to develop LN than other ethnic groups (p< 0.0001) but not less likely to die. Patients diagnosed before the median age of 28 years were significantly more likely to develop LN (p< 0.0001) but significantly less likely to die (p= 0.0039) during the period of observation. There has been a significant improvement in survival between patients diagnosed between 1978-1989 and those diagnosed between 2006-11 (p= 0.019). CONCLUSION: In our cohort, non-Caucasian ethnicity and younger age at diagnosis are associated with risk of developing LN. There is evidence of improvement in survival of patients with SLE over time

A one-point increase in the Damage Index for Antiphospholipid Syndrome (DIAPS) predicts mortality in thrombotic antiphospholipid syndrome

OBJECTIVES: To determine whether early damage and its kinetics measured by the Damage Index for Antiphospholipid Syndrome (DIAPS) predicts mortality. METHODS: We carried out a single-centre retrospective analysis of thrombotic APS patients (2006 Sydney criteria), using the DIAPS for damage assessment. Early damage was considered to be at six months after disease onset; early damage increase (delta-DIAPS) was deemed to be at least a one-point rise in DIAPS within the first five years of illness. Groups were compared using appropriate statistical tests. Survival was analysed by the Kaplan-Meier method. Cox regression analysis was performed to investigate predictors of mortality. RESULTS: A total of 197 patients (71.1% female; 65.9% primary APS; 72.4% Caucasian) were followed for up to 43 years (median 10). Damage developed in 143 (73.6%) patients. Twenty-three patients (12%) died. Secondary APS (HR 3.07, 95%CI 1.32-7.12, p=0.009), male sex (HR 3.14, 95%CI 1.35-7.33, p=0.008) and age at APS onset ≥40 years (HR 5.34, 95%CI 1.96-14.53, p=0.001) were risk factors for death. Early damage (n=69, 35.0%) was not associated with death (p=0.231). Having a first arterial event was associated with early damage (p<0.001), but not with delta-DIAPS (p=0.539) nor with the risk of death (p=0.151). Delta-DIAPS (n=53/181, 29.3%) predicted mortality (HR 5.40, 95%CI 2.33-12.52, p<0.001), even after adjusting individually for APS category (secondary), sex (male), early damage and age at APS onset (≥40 years) (all p<0.005). CONCLUSIONS: Evolving damage in the first five years of illness, but not early damage, predicted mortality regardless of the nature of the first thrombotic event, sex, APS category and age

High velocity spikes in Gowdy spacetimes

We study the behavior of spiky features in Gowdy spacetimes. Spikes with velocity initially high are, generally, driven to low velocity. Let n be any integer greater than or equal to 1. If the initial velocity of an upward pointing spike is between 4n-3 and 4n-1 the spike persists with final velocity between 1 and 2, while if the initial velocity is between 4n-1 and 4n+1, the spiky feature eventually disappears. For downward pointing spikes the analogous rule is that spikes with initial velocity between 4n-4 and 4n-2 persist with final velocity between 0 and 1, while spikes with initial velocity between 4n-2 and 4n eventually disappear.Comment: discussion of constraints added. Accepted for publication in Phys. Rev.

New Dimensions for Wound Strings: The Modular Transformation of Geometry to Topology

We show, using a theorem of Milnor and Margulis, that string theory on compact negatively curved spaces grows new effective dimensions as the space shrinks, generalizing and contextualizing the results in hep-th/0510044. Milnor's theorem relates negative sectional curvature on a compact Riemannian manifold to exponential growth of its fundamental group, which translates in string theory to a higher effective central charge arising from winding strings. This exponential density of winding modes is related by modular invariance to the infrared small perturbation spectrum. Using self-consistent approximations valid at large radius, we analyze this correspondence explicitly in a broad set of time-dependent solutions, finding precise agreement between the effective central charge and the corresponding infrared small perturbation spectrum. This indicates a basic relation between geometry, topology, and dimensionality in string theory.Comment: 28 pages, harvmac big. v2: references and KITP preprint number added, minor change

20 Paediatric SLE

Case 1: 9-year-old female with rash and oral ulcer Alexandre Belot Alisson is 9 years old and came to the outpatient unit with a rash and oral ulcer. Her past medical history highlighted two invasive infections (meningitidis and pneumonia). She had no muscular weakness, no lymphoproliferative disease and no fever. Her laboratory exams revealed: WBC: 2.5 G/L, with PNM=1.2G/L, Hb = 10 g/dl, Platelet = 135G/L, CRP = 10 mg/L. CPK and aldolase were within normal values. Serology for Epstein-Barr Virus, parvovirus B19 and measles were negative. Autoimmune check-up showed: ANA+ 1/1280, C3 and C4 normal, anti-dsDNA negative, anti SSA+ >8. The dosage of immunoglobulins was normal (including subclasses). She further developed severe systemic disease with lupus nephritis, white matter lesions at the cerebral MRI. Complement CH50 was dramatically decreased and her C1q level was undetectable. Discussion Points Explore complement deficiency in juvenile systemic lupus erythematosus (SLE) Discuss monogenic SLE Case 2: 13-year-old female with skin rash and chilblain Alexandre Belot Jade is 13 years old and has been recently diagnosed with juvenile SLE. Her past medical history revealed a pervasive developmental disorder with features of autism and mental delay. Her parents are first cousins. Her first symptoms were skin rash, chilblain. Following first-line therapy with hydroxychloroquine and topical steroids, she developed a polyarthritis with hepatitis and leukopenia. Abdominal sonography was normal. Autoantibodies for autoimmune liver disease (dot hepatitis) were negative. Treatment with steroids and methotrexate was introduced and effective on the joints. Further genetic exploration revealed a biallelic mutation of TREX1. Later on, she was treated with a JAK inhibitor in addition to methotrexate resulting in a positive outcome. Discussion Points Type I interferon in juvenile SLE Interferonopathies Case 3: 14-year-old male with haematuria and renal colic Alexandre Belot Michael presented a macroscopic hematuria with renal colic at the age of 14 years old. Sonography revealed a left nephromegaly without evidence of urinary tract obstruction. A CT scan showed a left renal venous thrombosis. Initial work-up identified a triple positivity for lupus anticoagulant, anti-B2 Gp-I and anti-cardiolipin antibodies. Anticoagulant therapy was initiated. dsDNA and ANA were negative and complement was normal. Six months later, the hematuria had completely disappeared, according to a urine dipstick test, but proteinuria was still present with a protein:creatinine ratio of 120 mg/mmol in the urine. A new doppler sonography and CT scan showed the absence of perfusion in the left kidney. Considering the proteinuria, a percutaneous biopsy was performed on the contralateral kidney and histology revealed Class V lupus nephritis. Notably, autoantibodies and complement were still normal. Rituximab and ACE inhibitors were introduced, and proteinuria rapidly disappeared. Discussion Points How to explore APS in children Management of thrombosis in pediatric autoimmune diseases Case 4: Anti-histone antibodies: does it always mean drug-induced lupus erythematosus? Rolando Cimaz A South-American 14-year-old girl presented with arthralgia, weakness and alopecia. As she was under antiepileptic treatment since she was 5 years old, on suspicion of drug-induced lupus erythematosus (DILE) anti-histone antibodies were dosed and showed positive results. She presented with mild anemia, leukopenia, hypocomplementemia, ANA, anti-dsDNA and LAC positivity. The antiepileptic therapy was initially modified and then, as no more crises were present, interrupted. However, anemia, leukopenia, hypocomplementemia, ANA and anti-dsDNA persisted, and the diagnosis of idiopathic systemic lupus erythematosus (SLE) was made. After treatment with hydroxychloroquine and low dose prednisone the girl clinically improved and her laboratory results normalized. This case report is suggestive of the complexity in differentiating SLE and DILE and underlines the importance of a long and careful follow-up. Discussion Points Medications that can trigger lupus symptomatology Triggers of lupus or of lupus-like disease (autoimmunity in general) with TNF inhibitors used for arthritis Risks of prescribing such medications (i.e. anti-TNF) in patients with inflammatory arthritis and pre-existing autoantibodies or a family history of autoimmune disease Case 5: Bleeding and thrombosis in juvenile systemic lupus erythematosus Rolando Cimaz A young girl with immune thrombocytopenic purpura was also found to have antiphospholipid antibody syndrome. This case describes the complexity of therapeutic management linked to the risk of bleeding and thrombosis. Irene is 15-year-old. In recent hours she has experienced intermittent claudication and lower right limb pain. Her physical exam reveals swelling and tenderness of right calf, pain to compression and mobilization of right foot. Laboratory tests reveal WBC 21.610 (N 77%); Hb 13.1 g/dl; PLT 91000/mmc; aPTT 48.4 sec, PT 99%; fibrinogen 236 mg/dl; D-Dimer 0.59 mg/L. Ultrasound revealed thrombosis. Past medical history showed that 8 months before she had suffered from severe metrorrhagia. Laboratory tests had shown: PLT 7000, Hb 10.2 g/dl, Coombs direct test +, PT 1.18, aPTT 76 sec; IgM e IgG anticardiolipin +. Therapy consisted in intravenous immunoglobulin (two infusions) and then oral steroids. Five relapses occurred, and laboratory showed: ANA+ (1:160), ENA -, anticardiolipin -, C3 85, C4 7.5, LAC +. Repeat laboratory test showed ANA+, ENA-, anticardiolipin +, anti-b2 glycoprotein -, LAC +. Discussion Points For thrombosis Heparin 6000U/x2/day. For how long? And for thrombocytopenia? Oral steroids (2 mg/kg/day); Mycophenolate mofetil (750 mg/m2 x 2/day). But despite this therapy, she relapsed. So > rituximab 750 mg/m2/2 weeks. For SLE hydroxychloroquine was given. Learning Objectives Distinguish between idiopathic and drug-induced SLE Describe the treatment of APS in children Discuss treatment options for hematologic SL

A novel expression system of domain I of human beta2 glycoprotein I in Escherichia coli

BACKGROUND: The antiphospholipid syndrome (APS), characterised by recurrent miscarriage and thrombosis, is a significant cause of morbidity and mortality. Domain I (DI) of human beta 2 glycoprotein I (β(2)GPI) is thought to contain crucial antibody binding epitopes for antiphospholipid antibodies (aPL), which are critical to the pathogenesis of APS. Expressing this protein in bacteria could facilitate studies investigating how this molecule interacts with aPL. METHODS: Using a computer programme called Juniper, sequentially overlapping primers were designed to be used in a recursive polymerase chain reaction (PCR) to produce a synthetic DI gene. Specifically Juniper incorporates 'major' codons preferred by bacteria altering 41 codons out of 61. This was cloned into the expression plasmid pET(26b) and expressed in BL21(DE3) Escherichia coli (E. coli). By virtue of a pelB leader sequence, periplasmic localisation of DI aided disulphide bond formation and toxicity was addressed by tightly regulating expression through the high stringency T7lac promoter. RESULTS: Purified, soluble his-tagged DI in yields of 750 μg/L bacterial culture was obtained and confirmed on Western blot. Expression using the native human cDNA sequence of DI in the same construct under identical conditions yielded significantly less DI compared to the recombinant optimised sequence. This constitutes the first description of prokaryotic expression of soluble DI of β(2)GPI. Binding to murine monoclonal antibodies that recognise conformationally restricted epitopes on the surface of DI and pathogenic human monoclonal IgG aPL was confirmed by direct and indirect immunoassay. Recombinant DI also bound a series of 21 polyclonal IgG samples derived from patients with APS. CONCLUSION: By producing a synthetic gene globally optimised for expression in E. coli, tightly regulating expression and utilising periplasmic product translocation, efficient, soluble E. coli expression of the eukaryotic protein DI of β(2)GPI is possible. This novel platform of expression utilising pan-gene prokaryote codon optimisation for DI production will aid future antigenic studies. Furthermore if DI or peptide derivatives of DI are eventually used in the therapeutic setting either as toleragen or as a competitive inhibitor of pathogenic aPL, then an E. coli production system may aid cost-effective production