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1.  NCR3/NKp30 contributes to pathogenesis in primary Sjögren’s syndrome 
Science translational medicine  2013;5(195):195ra96.
Primary Sjögren’s syndrome (pSS) is a chronic autoimmune disease characterized by a lymphocytic exocrinopathy. However, patients often have evidence of systemic autoimmunity and they are at markedly increased risk for the development of non- Hodgkin’s lymphoma. Similar to other autoimmune disorders, a strong interferon (IFN) signature is present among subsets of pSS patients, though the precise etiology remains uncertain. NCR3/NKp30 is a NK-specific activating receptor regulating the cross-talk between NK and dendritic cells and type II IFN secretion. We performed a case-control study of genetic polymorphisms of the NCR3/NKp30 gene and found that rs11575837 (G>A) residing in the promoter was associated with reduced gene transcription and function as well as protection to pSS. We also demonstrated that circulating levels of NCR3/NKp30 were markedly increased among pSS patients compared with controls and correlated with higher NCR3/NKp30 but not CD16-dependent IFN-γ secretion by NK cells. Excess accumulation of NK cells in minor salivary glands correlated with the severity of the exocrinopathy. B7H6, the ligand of NKp30, was expressed by salivary epithelial cells. These findings suggest that NK cells may promote an NKp30-dependent inflammatory state in salivary glands, and that blockade of the B7H6/NKp30 axis could be clinically relevant in pSS.
PMCID: PMC4237161  PMID: 23884468
Sjögren’s syndrome; autoimmunity; NK cells; innate immunity; NKp30/NCR3
2.  Variants at multiple loci implicated in both innate and adaptive immune responses are associated with Sjögren’s syndrome 
Nature genetics  2013;45(11):10.1038/ng.2792.
Sjögren’s syndrome is a common autoimmune disease (~0.7% of European Americans) typically presenting as keratoconjunctivitis sicca and xerostomia. In addition to strong association within the HLA region at 6p21 (Pmeta=7.65×10−114), we establish associations with IRF5-TNPO3 (Pmeta=2.73×10−19), STAT4 (Pmeta=6.80×10−15), IL12A (Pmeta =1.17×10−10), FAM167A-BLK (Pmeta=4.97×10−10), DDX6-CXCR5 (Pmeta=1.10×10−8), and TNIP1 (Pmeta=3.30×10−8). Suggestive associations with Pmeta<5×10−5 were observed with 29 regions including TNFAIP3, PTTG1, PRDM1, DGKQ, FCGR2A, IRAK1BP1, ITSN2, and PHIP amongst others. These results highlight the importance of genes involved in both innate and adaptive immunity in Sjögren’s syndrome.
PMCID: PMC3867192  PMID: 24097067
3.  Congenital heart block: evidence for a pathogenic role of maternal autoantibodies 
During pregnancy in autoimmune conditions, maternal autoantibodies are transported across the placenta and may affect the developing fetus. Congenital heart block (CHB) is known to associate with the presence of anti-Ro/SSA and anti-La/SSB antibodies in the mother and is characterized by a block in signal conduction at the atrioventricular (AV) node. The mortality rate of affected infants is 15% to 30%, and most live-born children require lifelong pacemaker implantation. Despite a well-recognized association with maternal anti-Ro/La antibodies, CHB develops in only 1% to 2% of anti-Ro-positive pregnancies, indicating that other factors are important for establishment of the block. The molecular mechanisms leading to complete AV block are still unclear, and the existing hypotheses fail to explain all aspects of CHB in one comprehensive model. In this review, we discuss the different specificities of maternal autoantibodies that have been implicated in CHB as well as the molecular mechanisms that have been suggested to operate, focusing on the evidence supporting a direct pathogenic role of maternal antibodies. Autoantibodies targeting the 52-kDa component of the Ro antigen remain the antibodies most closely associated with CHB. In vitro experiments and animal models of CHB also point to a major role for anti-Ro52 antibodies in CHB pathogenesis and suggest that these antibodies may directly affect calcium regulation in the fetal heart, leading to disturbances in signal conduction or electrogenesis or both. In addition, maternal antibody deposits are found in the heart of fetuses dying of CHB and are thought to contribute to an inflammatory reaction that eventually induces fibrosis and calcification of the AV node, leading to a complete block. Considering that CHB has a recurrence rate of 12% to 20% despite persisting maternal autoantibodies, it has long been clear that maternal autoantibodies are not sufficient for the establishment of a complete CHB, and efforts have been made to identify additional risk factors for this disorder. Therefore, recent studies looking at the influence of genetic and environmental factors will also be discussed.
PMCID: PMC3446439  PMID: 22546326
4.  Polymorphisms of the ITGAM Gene Confer Higher Risk of Discoid Cutaneous Than of Systemic Lupus Erythematosus 
PLoS ONE  2010;5(12):e14212.
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).
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.
PMCID: PMC2996302  PMID: 21151989
5.  Self Protection from Anti-Viral Responses – Ro52 Promotes Degradation of the Transcription Factor IRF7 Downstream of the Viral Toll-Like Receptors 
PLoS ONE  2010;5(7):e11776.
Ro52 is a member of the TRIM family of single-protein E3 ligases and is also a target for autoantibody production in systemic lupus erythematosus and Sjögren's syndrome. We previously demonstrated a novel function of Ro52 in the ubiquitination and proteasomal degradation of IRF3 following TLR3/4 stimulation. We now present evidence that Ro52 has a similar role in regulating the stability and activity of IRF7. Endogenous immunoprecipitation of Ro52-bound proteins revealed that IRF7 associates with Ro52, an effect which increases following TLR7 and TLR9 stimulation, suggesting that Ro52 interacts with IRF7 post-pathogen recognition. Furthermore, we show that Ro52 ubiquitinates IRF7 in a dose-dependent manner, resulting in a decrease in total IRF7 expression and a subsequent decrease in IFN-α production. IRF7 stability was increased in bone marrow-derived macrophages from Ro52-deficient mice stimulated with imiquimod or CpG-B, consistent with a role for Ro52 in the negative regulation of IRF7 signalling. Taken together, these results suggest that Ro52-mediated ubiquitination promotes the degradation of IRF7 following TLR7 and TLR9 stimulation. As Ro52 is known to be IFN-inducible, this system constitutes a negative-feedback loop that acts to protect the host from the prolonged activation of the immune response.
PMCID: PMC2909902  PMID: 20668674
6.  Loss of the lupus autoantigen Ro52/Trim21 induces tissue inflammation and systemic autoimmunity by disregulating the IL-23–Th17 pathway 
The Journal of Experimental Medicine  2009;206(8):1661-1671.
Ro52/Trim21 is targeted as an autoantigen in systemic lupus erythematosus and Sjögren's syndrome. Polymorphisms in the Ro52 gene have been linked to these autoimmune conditions, but the molecular mechanism by which Ro52 may promote development of systemic autoimmune diseases has not been explored. To address this issue, we generated Ro52-null mice (Ro52−/−), which appear phenotypically normal if left unmanipulated. However, Ro52−/− mice develop severe dermatitis extending from the site of tissue injury induced by ear tags. The affected mice further develop several signs of systemic lupus with hypergammaglobulinemia, autoantibodies to DNA, proteinuria, and kidney pathology. Ro52, which was recently identified as an E3 ligase, mediates ubiquitination of several members of the interferon regulatory factor (IRF) family, and the Ro52-deficient mice have an enhanced production of proinflammatory cytokines that are regulated by the IRF transcription factors, including cytokines involved in the Th17 pathway (interleukin [IL] 6, IL-12/IL-23p40, and IL-17). Loss of IL-23/IL-17 by genetic deletion of IL-23/p19 in the Ro52−/− mice conferred protection from skin disease and systemic autoimmunity. These data reveal that the lupus-associated Ro52 protein is an important negative regulator of proinflammatory cytokine production, and they provide a mechanism by which a defective Ro52 function can lead to tissue inflammation and systemic autoimmunity through the IL-23–Th17 pathway.
PMCID: PMC2722164  PMID: 19635858
7.  Differential effects on BAFF and APRIL levels in rituximab-treated patients with systemic lupus erythematosus and rheumatoid arthritis 
The objective of this study was to investigate the interaction between levels of BAFF (B-cell activation factor of the tumour necrosis factor [TNF] family) and APRIL (a proliferation-inducing ligand) and B-cell frequencies in patients with systemic lupus erythematosus (SLE) and rheumatoid arthritis (RA) treated with the B-cell-depleting agent rituximab. Ten patients with SLE were treated with rituximab in combination with cyclophosphamide and corticosteroids. They were followed longitudinally up to 6 months after B-cell repopulation. Nine patients with RA, resistant or intolerant to anti-TNF therapy, treated with rituximab plus methotrexate were investigated up to 6 months after treatment. The B-cell frequency was determined by flow cytometry, and serum levels of BAFF and APRIL were measured by enzyme-linked immunosorbent assays. BAFF levels rose significantly during B-cell depletion in both patient groups, and in patients with SLE the BAFF levels declined close to pre-treatment levels upon B-cell repopulation. Patients with SLE had normal levels of APRIL at baseline, and during depletion there was a significant decrease. In contrast, patients with RA had APRIL levels 10-fold higher than normal, which did not change during depletion. At baseline, correlations between levels of B cells and APRIL, and DAS28 (disease activity score using 28 joint counts) and BAFF were observed in patients with RA. In summary, increased BAFF levels were observed during absence of circulating B cells in our SLE and RA patient cohorts. In spite of the limited number of patients, our data suggest that BAFF and APRIL are differentially regulated in different autoimmune diseases and, in addition, differently affected by rituximab treatment.
PMCID: PMC1794511  PMID: 17092341
8.  Ro/SSA autoantibodies directly bind cardiomyocytes, disturb calcium homeostasis, and mediate congenital heart block 
Congenital heart block develops in fetuses after placental transfer of Ro/SSA autoantibodies from rheumatic mothers. The condition is often fatal and the majority of live-born children require a pacemaker at an early age. The specific antibody that induces the heart block and the mechanism by which it mediates the pathogenic effect have not been elucidated. In this study, we define the cellular mechanism leading to the disease and show that maternal autoantibodies directed to a specific epitope within the leucine zipper amino acid sequence 200–239 (p200) of the Ro52 protein correlate with prolongation of fetal atrioventricular (AV) time and heart block. This finding was further confirmed experimentally in that pups born to rats immunized with p200 peptide developed AV block. p200-specific autoantibodies cloned from patients bound cultured cardiomyocytes and severely affected Ca2+ oscillations, leading to accumulating levels and overload of intracellular Ca2+ levels with subsequent loss of contractility and ultimately apoptosis. These findings suggest that passive transfer of maternal p200 autoantibodies causes congenital heart block by dysregulating Ca2+ homeostasis and inducing death in affected cells.
PMCID: PMC2212767  PMID: 15630133

Results 1-8 (8)