Filippa Nyberg

The Sjögren’s Syndrome-Associated Autoantigen Ro52 Is an E3 Ligase That Regulates Proliferation and Cell Death

Patients affected by Sjögren’s syndrome and systemic lupus erythematosus (SLE) carry autoantibodies to an intracellular protein denoted Ro52. Although the serologic presence of Ro52 autoantibodies is used clinically for diagnostic purposes, the function of the protein or why it is targeted as an autoantigen in several rheumatic conditions has not been elucidated. In this study, we show that the expression of Ro52 is significantly increased in PBMC of patients with Sjögren’s syndrome and SLE, and demonstrate that Ro52 is a RING-dependent E3 ligase involved in ubiquitination. Overexpression of Ro52, but not of Ro52 lacking the RING domain, in a mouse B cell line lead to decreased growth in steady state and increased cell death after activation via the CD40 pathway. The role of Ro52 in activation-mediated cell death was further confirmed as a reduction in Ro52 expression restored cell viability. These findings suggest that the increased expression of the Ro52 autoantigen in patients may be directly involved in the reduced cellular proliferation and increased apoptotic cell death observed in Sjögren’s syndrome and SLE, and may thus contribute to the autoantigenic load and induction of autoimmune B and T cell responses observed in rheumatic patients.

Phase I, Randomized, Double-Blind, Placebo-Controlled, Multiple Intravenous, Dose-Ascending Study of Sirukumab in Cutaneous or Systemic Lupus Erythematosus

OBJECTIVE We undertook a 2-part, phase I, double-blind, placebo-controlled study to evaluate the safety and pharmacokinetics of multiple intravenous infusions of sirukumab, a human anti-interleukin-6 monoclonal antibody, in patients with cutaneous lupus erythematosus (CLE) or systemic lupus erythematosus (SLE). METHODS In part A, patients with histologically confirmed CLE were randomized to 4 infusions of placebo or 1, 4, or 10 mg/kg sirukumab every 2 weeks. In part B, SLE patients diagnosed according to American College of Rheumatology criteria with a score of 5-12 on the Safety of Estrogens in Lupus Erythematosus National Assessment version of the SLE Disease Activity Index were randomized to 4 infusions of placebo or 10 mg/kg sirukumab every 2 weeks. RESULTS We treated 31 CLE patients (23 with sirukumab, 8 with placebo) and 15 SLE patients (10 with sirukumab, 5 with placebo). Adverse events (AEs) occurred more often with sirukumab than placebo in CLE patients (91% versus 63%) and in SLE patients (90% versus 80%). Sirukumab led to sustained, dose-independent decreases in white blood cell counts, absolute neutrophil counts (neutropenia), and platelet counts (thrombocytopenia) and to minor elevations in total cholesterol levels. The majority of infections were mild respiratory infections. which were reported similarly across CLE cohorts but more often in sirukumab-treated than in placebo-treated SLE patients. Two serious AEs of infection occurred (pneumonia in the 10 mg/kg-treated group and iatrogenic wound infection in the 4 mg/kg-treated group). Sirukumab showed linear pharmacokinetics in CLE patients. Systemic exposure and half-life were comparable between CLE and SLE patients. No patient developed antibodies to sirukumab through 22 weeks. C-reactive protein and serum amyloid A mean concentrations were suppressed with sirukumab from week 1 to week 14. CONCLUSION Treatment with intravenous sirukumab infusions was generally well tolerated in both CLE and SLE patients with mild, stable, active disease. Sirukumab demonstrated linear pharmacokinetics over the dose range studied and comparable systemic exposure and half-life in CLE and SLE patients.

Translocation of the novel cytokine HMGB1 to the cytoplasm and extracellular space coincides with the peak of clinical activity in experimentally UV-induced lesions of cutaneous lupus erythematosus

HMGB1 is a pro-inflammatory cytokine that together with TNF-α and IL-1β is involved in the pathogenesis of spontaneously occurring skin lesions in lupus erythematosus. The purpose of the present study was to explore the sequence of events in HMGB1, TNF-α and IL-1β expression under development and resolution of experimentally induced CLE lesions. The study involved investigation of 38 serial skin biopsies acquired from photoprovoked skin lesions of nine CLE patients, using immunohistochemical staining of tissue sections. In biopsies from the clinically most active phase of skin involvement extracellular, secreted HMGB1 and increased cytoplasmic HMGB1 were found, as compared with the late and fading lesions or non-lesional skin. Besides HMGB1, increased expression of TNF-α and IL-1β was observed in dermal infiltrates of the induced CLE lesions. These cytokines were however not upregulated in all lesions, and increased expression of IL-1β was seen predominantly in late biopsies. In conclusion, extracellular and cytoplasmic HMGB1 coincides with the clinically most active phase of photoinduced lesions of cutaneous lupus, and suggests that HMGB1 is an important factor in the inflammatory autoimmune process of CLE. HMGB1 can induce expression of TNF-α and IL-1β, and formation of a pro-inflammatory loop between HMGB1, TNF-α, and IL-1β may be responsible for the prolonged and sustained inflammation in CLE. Lupus (2007) 16, 794—802.

High Ro52 Expression in Spontaneous and UV-Induced Cutaneous Inflammation

Ro52 is an E3 ubiquitin ligase with a recently identified regulatory role in inflammation. The protein is targeted by autoantibodies in rheumatic diseases, and Ro52 autoantibodies are specifically associated with cutaneous lupus erythematosus (CLE) and photosensitivity. The aim of this study was to investigate cutaneous Ro52 expression in CLE patients and to examine whether UVR might modulate Ro52. Ro52 expression was assessed by immunohistochemistry in biopsies derived from CLE lesions (n=25), nonlesional (n=7), and healthy control skin using four anti-Ro52 mAbs generated by us. Ro52 expression was also analyzed in psoriatic, lichenoid, and eczematous lesions. It was increased in the epidermis of spontaneous CLE lesions as compared with unaffected skin of patients and healthy controls. High epidermal Ro52 expression was also observed in other inflammatory dermatoses investigated. Ro52 was upregulated in experimentally photoprovoked CLE lesions as observed by immunohistochemistry in sequential biopsies, which was confirmed in vitro both at the mRNA and protein levels by exposing cultured patient-derived primary keratinocytes to UVR. In conclusion, Ro52 expression is upregulated in keratinocytes in inflammatory skin conditions and in response to UVR. High Ro52 expression might lead to the breaking of tolerance and the generation of Ro52 autoantibodies in genetically susceptible subjects. Further, the upregulation of Ro52 in keratinocytes after sun exposure might also be a triggering factor for skin lesions in patients with Ro52 antibodies.

Gender and the treatment of immune-mediated chronic inflammatory diseases: rheumatoid arthritis, inflammatory bowel disease and psoriasis: an observational study

BackgroundRheumatoid arthritis (RA), inflammatory bowel disease (IBD), and psoriasis are immune-mediated inflammatory diseases with similarities in pathophysiology, and all can be treated with similar biological agents. Previous studies have shown that there are gender differences with regard to disease characteristics in RA and IBD, with women generally having worse scores on pain and quality of life measurements. The relationship is less clear for psoriasis. Because treatment differences between men and women could explain the dissimilarities, we investigated gender differences in the disease characteristics before treatment initiation and in the biologic treatment prescribed.MethodsData on patients with RA or IBD were collected from two registries in which patients treated with biologic medication were enrolled. Basic demographic data and disease activity parameters were collected from a time point just before the initiation of the biologic treatment. For patients with psoriasis, the data were taken from the 2010 annual report of the Swedish Psoriasis Register for systemic treatment, which included also non-biologic treatment. For all three diseases, the prescribed treatment and disease characteristics were compared between men and women.ResultsIn total, 4493 adult patients were included in the study (1912 with RA, 131 with IBD, and 2450 with psoriasis). Most of the treated patients with RA were women, whereas most of the patients with IBD or psoriasis were men. There were no significant differences between men and women in the choice of biologics. At treatment start, significant gender differences were seen in the subjective disease measurements for both RA and psoriasis, with women having higher (that is, worse) scores than men. No differences in objective measurements were found for RA, but for psoriasis men had higher (that is, worse) scores for objective disease activity measures. A similar trend to RA was seen in IBD.ConclusionsWomen with RA or psoriasis scored significantly higher on subjective, but not on objective, disease activity measures than men, and the same trend was seen in IBD. This indicates that at the same level of treatment, the disease has a greater effect in women. These findings might suggest that in all three diseases, subjective measures are discounted to some extent in the therapeutic decision-making process, which could indicate undertreatment in female patients.

The protective effect of farm animal exposure on childhood allergy is modified by NPSR1 polymorphisms

Background: Little is known about the asthma candidate gene neuropeptide S receptor 1 (NPSR1) in relation to environmental exposures, but recent evidences suggest its role as an effect modifier. Objectives: To explore the interaction between NPSR1 polymorphisms and environmental exposures related to farming lifestyle and to study the in vitro effects of lipopolysaccharide (LPS) stimulation on NPSR1 expression levels. Methods: We studied 3113 children from PARSIFAL, a European cross-sectional study on environmental/lifestyle factors and childhood allergy, partly focused on children brought up on a farm. Information on exposures and outcomes was primarily obtained from parental questionnaires. Seven tagging polymorphisms were analysed in a conserved haplotype block of NPSR1. Multivariate logistic regression was used to evaluate a multiplicative model of interaction. NPSR1 protein and messenger RNA (mRNA) levels in monocytes were measured after LPS stimulation by fluorescence activated cell sorting (FACS) and quantitative real-time polymerase chain reaction (PCR). Results: A strong interaction was seen between current regular contact to farm animals and several NPSR1 polymorphisms, particularly rs323922 and rs324377 (p<0.005), with respect to allergic symptoms. Considering the timing of initiation of such current regular farm animal contact, significant interactions with these and two additional polymorphisms (SNP546333, rs740347) were revealed. In response to LPS, NPSR1-A protein levels in monocytes were upregulated (p = 0.002), as were NPSR1-A mRNA levels (p = 0.02). Conclusions: The effect of farm animal contact on the development of allergic symptoms in children is modified by NPSR1 genetic background.

Anti-Ro52 Autoantibodies from Patients with Sjögren's Syndrome Inhibit the Ro52 E3 Ligase Activity by Blocking the E3/E2 Interface

Ro52 (TRIM21) is an E3 ligase of the tripartite motif family that negatively regulates proinflammatory cytokine production by ubiquitinating transcription factors of the interferon regulatory factor family. Autoantibodies to Ro52 are present in patients with lupus and Sjögrens syndrome, but it is not known if these autoantibodies affect the function of Ro52. To address this question, the requirements for Ro52 E3 ligase activity were first analyzed in detail. Scanning a panel of E2 ubiquitin-conjugating enzymes, we found that UBE2D1–4 and UBE2E1–2 supported the E3 ligase activity of Ro52 and that the E3 ligase activity of Ro52 was dependent on its RING domain. We also found that the N-terminal extensions in the class III E2 enzymes affected their interaction with Ro52. Although the N-terminal extension in UBE2E3 made this E2 enzyme unable to function together with Ro52, the N-terminal extensions in UBE2E1 and UBE2E2 allowed for a functional interaction with Ro52. Anti-Ro52-positive patient sera and affinity-purified anti-RING domain autoantibodies inhibited the E3 activity of Ro52 in ubiquitination assays. Using NMR, limited proteolysis, ELISA, and Ro52 mutants, we mapped the interactions between Ro52, UBE2E1, and anti-Ro52 autoantibodies. We found that anti-Ro52 autoantibodies inhibited the E3 ligase activity of Ro52 by sterically blocking the E2/E3 interaction between Ro52 and UBE2E1. Our data suggest that anti-Ro52 autoantibodies binding the RING domain of Ro52 may be actively involved in the pathogenesis of rheumatic autoimmune disease by inhibiting Ro52-mediated ubiquitination.

Polymorphisms of the ITGAM Gene Confer Higher Risk of Discoid Cutaneous than of Systemic Lupus Erythematosus

Background Lupus erythematosus (LE) is a heterogeneous disease ranging from mainly skin-restricted manifestations (discoid LE [DLE] and subacute cutaneous LE) to a progressive multisystem disease (systemic LE [SLE]). Genetic association studies have recently identified several strong susceptibility genes for SLE, including integrin alpha M (ITGAM), also known as CD11b, whereas the genetic background of DLE is less clear. Principal Findings To specifically investigate whether ITGAM is a susceptibility gene not only for SLE, but also for cutaneous DLE, we genotyped 177 patients with DLE, 85 patients with sporadic SLE, 190 index cases from SLE families and 395 population control individuals from Finland for nine genetic markers at the ITGAM locus. SLE patients were further subdivided by the presence or absence of discoid rash and renal involvement. In addition, 235 Finnish and Swedish patients positive for Ro/SSA-autoantibodies were included in a subphenotype analysis. Analysis of the ITGAM coding variant rs1143679 showed highly significant association to DLE in patients without signs of systemic disease (P-value  = 4.73×10−11, OR  = 3.20, 95% CI  = 2.23–4.57). Significant association was also detected to SLE patients (P-value  = 8.29×10−6, OR  = 2.14, 95% CI  = 1.52–3.00), and even stronger association was found when stratifying SLE patients by presence of discoid rash (P-value  = 3.59×10−8, OR  = 3.76, 95% CI  = 2.29–6.18). Significance We propose ITGAM as a novel susceptibility gene for cutaneous DLE. The risk effect is independent of systemic involvement and has an even stronger genetic influence on the risk of DLE than of SLE.

Photoprovocation in Cutaneous Lupus Erythematosus: A Multicenter Study Evaluating a Standardized Protocol

Photosensitivity is an important and distinguishing sign in various subtypes of cutaneous lupus erythematosus (CLE); however, it remains poorly defined. The purpose of this study was to evaluate whether standardized photoprovocation is a reproducible method to assess photosensitivity in subjects with CLE. A total of 47 subjects with CLE (subacute cutaneous lupus erythematosus (SCLE), n=14; discoid lupus erythematosus (DLE), n=20; lupus erythematosus tumidus (LET), n=13) and 13 healthy volunteers underwent photoprovocation at seven European sites. Of these, 22 (47%) subjects (57% SCLE, 35% DLE, and 54% LET) and none of the healthy volunteers developed photoprovoked lesions according to clinical analysis. Of these 22 subjects, 19 (86%) developed lesions that were histopathologically confirmed as specific for lupus erythematosus (LE). In CLE subjects who developed UV-induced lesions, 86% had Fitzpatricks phototypes I or II, and the mean minimal erythema dose (MED) was significantly lower compared with subjects without UV-induced lesions (P=0.004). No significant differences in photoprovocation results were observed between study sites. Safety parameters showed no clinically meaningful differences between CLE subjects and healthy volunteers after photoprovocation. In conclusion, a standardized, safe, and reproducible protocol for photoprovocation using UVA and UVB radiation induced skin lesions in approximately half of all CLE subjects and showed comparable results across multiple sites. This method may therefore be used for future diagnostic testing and clinical trials.

Electrical impedance spectroscopy as a potential adjunct diagnostic tool for cutaneous melanoma

Previous studies have shown statistically significant differences in electrical impedance between various cutaneous lesions. Electrical impedance spectroscopy (EIS) may therefore be able to aid clinicians in differentiating between benign and malignant skin lesions.