Abstract 548: TLT-1 as a Possible Modulator of Systemic Lupus Erythematosus

Systemic lupus erythematosus (SLE) is an autoimmune disease characterized by immune system hyperactivity and autoantibody production that can affect almost any organ system. TREM like transcript-1 (TLT-1) is a membrane receptor found in platelets α-granules with activating properties. We have demonstrated that activated platelets release a soluble isoform of TLT-1 (sTLT-1) which is not found in the plasma of healthy individuals. Moreover, evaluation of patients suffering from inflammatory diseases, such as sepsis, reveals a significant increase of plasma sTLT-1 levels. It is not known if TLT-1 plays a role in auto immune diseases such as Lupus. In the present study we evaluate the potential that TLT-1 may play a role in the etiology of SLE. We assessed the plasma of 46 SLE patients and compared to 28 healthy controls by ELISA. Our results showed that SLE patients had a significant decrease in plasma sTLT-1 levels compared to healthy controls (9.0 [7.2] vs. 18.6 [22.3] ng/ml, p=0.008). A negative correlation was observed between TLT-1 levels and LupusPRO [lupus symptoms (r = -0.388, p = 0.055). Based on this data; we hypothesize that SLE patients produce autoantibodies against TLT-1 in serum which might correlate with clinical aspects of the disease . To address this question; TLT-1 antibodies levels in serum were measured by ELISA. Our data suggests that a sub-population of SLE patients have TLT-1 autoantibodies. This data was further confirmed by confocal microscopy. Using human embryonal kidney cells (HEKt) stably transfected with TLT-1, we evaluated the serum of SLE patients for the presence of TLT-1 autoantibodies using immunofluorescence. Our data confirms that a sub-population of SLE patients with active disease is expressing antibodies against TLT-1. These findings suggest a possible role for TLT-1 during the pathogenesis of SLE and targets new treatment possibilities for lupus patients.

Two functional lupus-associated BLK promoter variants control cell-type- and developmental-stage-specific transcription

Efforts to identify lupus-associated causal variants in the FAM167A/BLK locus on 8p21 are hampered by highly associated noncausal variants. In this report, we used a trans-population mapping and sequencing strategy to identify a common variant (rs922483) in the proximal BLK promoter and a tri-allelic variant (rs1382568) in the upstream alternative BLK promoter as putative causal variants for association with systemic lupus erythematosus. The risk allele (T) at rs922483 reduced proximal promoter activity and modulated alternative promoter usage. Allelic differences at rs1382568 resulted in altered promoter activity in B progenitor cell lines. Thus, our results demonstrated that both lupus-associated functional variants contribute to the autoimmune disease association by modulating transcription of BLK in B cells and thus potentially altering immune responses.

Association of the use of statins with disease activity and functional status in Puerto Ricans with rheumatoid arthritis

OBJECTIVE

Statins, which appear to have anti-inflammatory and immunomodulatory effects, may benefit patients with rheumatoid arthritis (RA). Our study sought to determine the association of statins use with disease activity and functional status in a group of patients with RA.

METHODS

A cross-sectional study was performed in 209 Puerto Ricans with RA (per the 1987 classification criteria of the American College of Rheumatology). Demographic features, lifestyle-related behaviors, disease activity (per Disease Activity Score 28), comorbid conditions, functional status (per Health Assessment Questionnaire), pharmacologic therapy, and patients' and physicians' global assessments using visual analogue scales, were determined. Data were examined using univariate, bivariate, and multiple logistic regression analyses.

RESULTS

The mean (standard deviation [SD]) age of the study population at study visit was 56.8 (13.5) years (range: 24-86 years); 175 patients (83.7%) were women. The mean (SD) disease duration was 10.4 (9.5) years (range: 0.0-44.0 years). Thirty-two (15.3%) patients were using statins at study visit, and 36 (17.2%) had used statins in the past. In the multivariable analysis, the current use of statins was associated with higher functional status (odds ratio 0.42, 95% confidence interval 0.22-0.80) than was nonuse, after adjusting for age, disease duration, arterial hypertension, coronary artery disease, and dyslipidemia. No association between either current or past use of statins and disease activity was found.

CONCLUSION

In this group of RA patients, the current use of statins was associated with a higher functional status; conversely, no association was found between statins use and disease activity. However, larger and longitudinal studies are required to confirm these findings.

Effects of statins on proinflammatory/prothrombotic biomarkers and on disease activity scores in SLE patients: data from LUMINA (LXXVI), a multi-ethnic US cohort

OBJECTIVES

We sought to determine the effect of statin therapy on the levels of proinflammatory/prothrombotic markers and disease activity scores in patients with SLE in a multi-ethnic, multi-centre cohort (LUMINA).

METHODS

Plasma/serum samples from SLE patients placed on statins (n=21) therapy taken before and after at least 6 months of treatment were tested. Disease activity was assessed using SLAM-R scores. Interleukin (IL)-1β, IL-6, IL-8, tumour necrosis factor (TNF)-α, vascular endothelial growth factor (VEGF) and soluble CD40 ligand (sCD40L) levels were determined by a multiplex immunoassay. Soluble intercellular cell adhesion molecule (ICAM)-1, vascular cell adhesion molecule (VCAM)-1 and anticardiolipin (aCL) antibodies were evaluated using ELISA assays while high sensitivity C-reactive protein (hsCRP) was assessed by nephelometry. Plasma/serum samples from frequency- matched healthy donors were used as controls.

RESULTS

Levels of IL-6, VEGF, sCD40L and TNF-α were significantly elevated in SLE patients versus controls. Statin therapy resulted in a significant decrease in SLAM-R scores (p=0.0199) but no significant changes in biomarker levels were observed. There was no significant association of biomarkers with SLAM-R scores.

CONCLUSIONS

Statin therapy resulted in significant clinical improvement in SLE patients, underscoring the use of statins in the treatment of SLE.

Factors associated with regional rheumatic pain disorders in a population of Puerto Ricans with diabetes mellitus

The aim of the study was to determine the prevalence and factors associated with bursitis/tendonitis disorders in Puerto Ricans with diabetes mellitus (DM). A cross-sectional study was performed in 202 adult Puerto Ricans (100 DM patients and 102 non-diabetic subjects). For each participant, a complete medical history and a musculoskeletal exam were systematically performed. Socio-demographic parameters, health-related behaviors, comorbidities, and pharmacotherapy were determined for all subjects. For DM patients, disease duration, glycemic control, and DM long-term complications were also examined. Multivariate logistic regression analyses were used to determine the factors associated with bursitis/tendonitis disorders. The mean (SD) age for DM patients and non-diabetic controls were 53.3 (12.9) and 50.0 (13.1) years; 64.0 and 64.7 % of DM patients and controls were females, respectively. Overall, the prevalence of bursitis/tendonitis was higher in DM patients than among non-diabetics (59.0 % vs. 29.4 %, p < 0.01). In multivariate analyses, DM patients had 2.47 (95 % CI 1.05, 5.84) the odds of having bursitis/tendonitis as compared to non-diabetics. Specifically, DM patients had a higher frequency of flexor tenosynovitis, De Quervain's tenosynovitis, lateral epicondylitis, medial epicondylitis, trochanteric bursitis, and anserine bursitis than non-diabetic subjects (p < 0.05). Among DM patients, multivariate analyses showed that those with bursitis/tendonitis were more likely to be female [OR (95 % CI) 4.55 (1.42, 14.55)] and have peripheral vascular disease [OR (95 % CI) 8.48 (1.71, 41.93)]. In conclusion, bursitis/tendonitis disorders were common in this population of Hispanics with DM. Among DM patients, bursitis/tendonitis disorders were more frequent in women and those with long-term complications such as peripheral vascular disease.

Value of isolated IgA anti-β2 -glycoprotein I positivity in the diagnosis of the antiphospholipid syndrome

OBJECTIVE

To examine the prevalence of isolated IgA anti-β2 -glycoprotein I (anti-β2 GPI) positivity and the association of these antibodies, and a subgroup that bind specifically to domain IV/V of β2 GPI, with clinical manifestations of the antiphospholipid syndrome (APS) in 3 patient groups and to evaluate the pathogenicity of IgA anti-β2 GPI in a mouse model of thrombosis.

METHODS

Patients with systemic lupus erythematosus (SLE) from a multiethnic, multicenter cohort (LUpus in MInorities, NAture versus nurture [LUMINA]) (n = 558), patients with SLE from the Hopkins Lupus Cohort (n = 215), and serum samples referred to the Antiphospholipid Standardization Laboratory (APLS) (n = 5,098) were evaluated. IgA anti-β2 GPI titers and binding to domain IV/V of β2 GPI were examined by enzyme-linked immunosorbent assay (ELISA). CD1 mice were inoculated with purified IgA anti-β2 GPI antibodies, and surgical procedures and ELISAs were performed to evaluate thrombus development and tissue factor (TF) activity.

RESULTS

A total of 198 patients were found to be positive for IgA anti-β2 GPI isotype, and 57 patients were positive exclusively for IgA anti-β2 GPI antibodies. Of these, 13 of 23 patients (56.5%) in the LUMINA cohort, 17 of 17 patients (100%) in the Hopkins cohort, and 10 of 17 patients (58.9%) referred to APLS had at least one APS-related clinical manifestation. Fifty-four percent of all the IgA anti-β2 GPI-positive serum samples reacted with domain IV/V of anti-β2 GPI, and 77% of those had clinical features of APS. Isolated IgA anti-β2 GPI positivity was associated with an increased risk of arterial thrombosis (P < 0.001), venous thrombosis (P = 0.015), and all thrombosis (P < 0.001). The association between isolated IgA anti-β2 GPI and arterial thrombosis (P = 0.0003) and all thrombosis (P = 0.0003) remained significant after adjusting for other risk factors for thrombosis. In vivo mouse studies demonstrated that IgA anti-β2 GPI antibodies induced significantly larger thrombi and higher TF levels compared to controls.

CONCLUSION

Isolated IgA anti-β2 GPI-positive titers may identify additional patients with clinical features of APS. Testing for these antibodies when other antiphospholipid tests are negative and APS is suspected is recommended. IgA anti-β2 GPI antibodies directed to domain IV/V of β2 GPI represent an important subgroup of clinically relevant antiphospholipids.

Infective endocarditis initially presenting with a dermatomyositis-like syndrome

Infective endocarditis (IE) may present with rheumatological manifestations such as myalgias, arthralgias, arthritis and back pain. However, muscle inflammation is rare. We present a case of a 68-year-old Hispanic man who presented with 1-month history of tiredness, weight loss, fever, myalgias, muscle weakness and dysphagia to solid food. On physical examination he had severe weakness in the proximal upper and lower extremities, and erythematous eruption involving the upper eyelids, neck and metacarpophalangeal joints. Creatine kinase levels were markedly elevated at 15 809 U/L. MRI of the right thigh revealed intermuscular and intramuscular oedema. Muscle biopsy showed acute necrotising suppurative perimyositis. Blood cultures were positive for methicillin-resistant Staphylococcus aureus. A transoesophageal echocardiogram revealed vegetations in the pulmonic valve. All clinical manifestations were resolved completely with broad-spectrum antibiotics. This case suggests that IE should be considered in the differential diagnosis of a patient presenting with inflammatory myopathy.

Osteoporosis knowledge in patients with a first fragility fracture in Puerto Rico

PURPOSE

To determine the level of knowledge about osteoporosis and factors associated with low level of knowledge in patients with a first osteoporotic fracture.

METHODS

A cross-sectional study in adult patients with a first osteoporotic fracture admitted to the University Hospital of the Puerto Rico Medical Center, San Juan, Puerto Rico was performed. Socio-demographic parameters, clinical features, and pharmacologic treatment were examined. A validated questionnaire was used to assess subjects' level of knowledge about osteoporosis. Differences between study groups were evaluated using chi-square and Student's t tests, as appropriate.

RESULTS

A total of 54 patients participated in the study. The mean (SD) age was 73.7 (10.7) years; 77.8% were females. Overall, 61.1% of the participants had a low level of knowledge about osteoporosis. Patients with low level of knowledge were more likely to have the Puerto Rico Government health insurance, lower level of education, and higher hip FRAX scores than those with mid/high level of knowledge. Also, they were less likely to receive osteoporosis counseling by their primary care physicians (PCP), have prior BMD measurement, receive bisphosphonates/raloxifene treatment, and to take calcium and vitamin D supplements.

CONCLUSIONS

In this population of Hispanic patients with a first osteoporotic fracture, the majority had a low level of knowledge about osteoporosis. Low knowledge was associated with low socio-economic status, lack of counseling about osteoporosis by PCP, prior BMD measurement, and osteoporosis treatment. Better efforts should be undertaken to educate, identify, and manage patients at risk for osteoporotic fractures.

Lymphocyte sensitivity assay as a marker for glucocorticoid resistance in lupus: report of two sisters with systemic lupus erythematosus

Glucocorticoid sensitivity can be measured in vitro using the lymphocyte sensitivity assay (LSA). In this test, dexamethasone is used to inhibit the proliferation of peripheral blood mononuclear cells (PBMC) in response to mitogens. If the proliferation of PBMC is suppressed the subjects are considered to be GC sensitive; if not, they are considered to be resistant. The LSA has been used to test GC sensitivity in some inflammatory diseases but its clinical value in systemic lupus erythematosus (SLE) has not been determined. Herein, we present the results of the LSA from two sisters with SLE who had different disease outcomes. Patient 1 presented with higher disease activity and damage accrual, and poorer response to corticosteroids than patient 2. In the LSA, patient 1 had a lower dexamethasone suppression of mitogen-stimulated PBMC than patient 2 and one control subject. The LSA could be helpful in identifying patients with GC resistance, thus allowing the consideration of alternative immunosuppressive drugs.

PTPN22 association in systemic lupus erythematosus (SLE) with respect to individual ancestry and clinical sub-phenotypes

Protein tyrosine phosphatase non-receptor type 22 (PTPN22) is a negative regulator of T-cell activation associated with several autoimmune diseases, including systemic lupus erythematosus (SLE). Missense rs2476601 is associated with SLE in individuals with European ancestry. Since the rs2476601 risk allele frequency differs dramatically across ethnicities, we assessed robustness of PTPN22 association with SLE and its clinical sub-phenotypes across four ethnically diverse populations. Ten SNPs were genotyped in 8220 SLE cases and 7369 controls from in European-Americans (EA), African-Americans (AA), Asians (AS), and Hispanics (HS). We performed imputation-based association followed by conditional analysis to identify independent associations. Significantly associated SNPs were tested for association with SLE clinical sub-phenotypes, including autoantibody profiles. Multiple testing was accounted for by using false discovery rate. We successfully imputed and tested allelic association for 107 SNPs within the PTPN22 region and detected evidence of ethnic-specific associations from EA and HS. In EA, the strongest association was at rs2476601 (P = 4.7 × 10(-9), OR = 1.40 (95% CI = 1.25-1.56)). Independent association with rs1217414 was also observed in EA, and both SNPs are correlated with increased European ancestry. For HS imputed intronic SNP, rs3765598, predicted to be a cis-eQTL, was associated (P = 0.007, OR = 0.79 and 95% CI = 0.67-0.94). No significant associations were observed in AA or AS. Case-only analysis using lupus-related clinical criteria revealed differences between EA SLE patients positive for moderate to high titers of IgG anti-cardiolipin (aCL IgG >20) versus negative aCL IgG at rs2476601 (P = 0.012, OR = 1.65). Association was reinforced when these cases were compared to controls (P = 2.7 × 10(-5), OR = 2.11). Our results validate that rs2476601 is the most significantly associated SNP in individuals with European ancestry. Additionally, rs1217414 and rs3765598 may be associated with SLE. Further studies are required to confirm the involvement of rs2476601 with aCL IgG.

Association of hand or knee osteoarthritis with diabetes mellitus in a population of Hispanics from Puerto Rico

BACKGROUND

Although a higher prevalence of osteoarthritis (OA) has been reported among diabetes mellitus (DM) patients, inconsistencies and limitations of observational studies have precluded a conclusive association.

OBJECTIVE

The objective of this study was to evaluate the association of hand or knee OA with DM in a population of Hispanics from Puerto Rico.

METHODS

A cross-sectional study was performed in 202 subjects (100 adult DM patients as per the National Diabetes Data Group Classification and 102 nondiabetic subjects). Osteoarthritis of hand and knee was ascertained using the American College of Rheumatology classification criteria. Sociodemographic characteristics, health-related behaviors, comorbidities, pharmacotherapy, and DM clinical manifestations were determined. Multivariable logistic regression was used to evaluate the association of DM with hand or knee OA and to evaluate factors associated with hand or knee OA among DM patients.

RESULTS

The mean (SD) age for DM patients was 51.6 (13.1) years; 64.0% were females. The mean (SD) DM duration was 11.0 (10.4) years. The prevalence of OA in patients with DM and nondiabetic subjects was 49.0% and 26.5%, respectively (P < 0.01). In the multivariable analysis, patients with DM had 2.18 the odds of having OA when compared with nondiabetic subjects (95% confidence interval [CI], 1.12-4.24). In a subanalysis among DM patients, female patients were more likely to have hand or knee OA (odds ratio [95% CI], 5.06 [1.66-15.66]), whereas patients who did not use insulin alone for DM therapy were more likely to have OA (odds ratio [95% CI], 4.44 [1.22-16.12]).

CONCLUSIONS

In this population of Hispanics from Puerto Rico, DM patients were more likely to have OA of hands or knees than were nondiabetic subjects. This association was retained in multivariable models accounting for established risk factors for OA. Among DM patients, females were at greater risk for OA, whereas the use of insulin was negatively associated.

Recurrent venous thrombosis in Ehlers-Danlos syndrome type III: an atypical manifestation

Ehlers-Danlos syndrome (EDS) comprises a group of hereditary connective tissue disorders in which collagen synthesis and fibrogenesis are impaired. Patients with EDS type III have a bleeding tendency manifested by ecchymoses and haematomas. However, thrombotic events are rare in this entity. Herein, we present a 48-year-old Hispanic man with EDS type III who had recurrent cephalic vein thrombophlebitis and thrombosis, and brachial vein thrombosis. Tests for hypercoagulable disorders including antithrombin III activity, protein C activity, protein S activity, anticardiolipin antibodies, homocysteine levels, factor V Leiden mutation and prothrombin gene mutation were negative. The patient required long-term anticoagulation with warfarin. After 3 years follow-up, he did not present further thrombotic events. Clinicians should be aware that patients with EDS might be at risk for hypercoagulable disorders.

Efficacy of low-dose intravenous cyclophosphamide in systemic lupus erythematosus presenting with Guillain-Barre syndrome-like acute axonal neuropathies: report of two cases

There are few cases of Guillain-Barré syndrome (GBS), particularly of atypical variants, occurring in association with systemic lupus erythematous (SLE). Reports addressing a specific therapy thus remain almost anecdotal. It is therefore challenging to determine the treatment that is best suited for this subset of patients, especially if initial conventional therapy for GBS fails. We present two cases of GBS-like acute axonal neuropathies, one with acute motor axonal neuropathy (AMAN), and another with acute motor sensory axonal neuropathy (AMSAN), presenting early in the course of SLE. The first case failed to respond to therapy with intravenous immunoglobulins (IVIG) and plasmapheresis, but achieved a favorable outcome when high-dose glucocorticoids along with low-dose intravenous (IV) cyclophosphamide pulses were given. The second case responded favorably to high-dose glucocorticoids, IVIG, and low-dose IV cyclophosphamide pulses. Both patients have remained in clinical remission and without neurologic sequelae after 10 and three years of follow-up, respectively.

Inflammatory myopathy as the initial presentation of cryoglobulinaemic vasculitis

Cryoglobulinaemic vasculitis is characterised by immunoglobulin deposition at low temperatures. The most common manifestations are cutaneous involvement, arthralgias, Raynaud's phenomenon, peripheral neuropathy and renal disease. Myopathy is unusual and only a few cases have been reported. Here, we present a 31-year-old woman who developed progressive muscle weakness involving upper and lower extremities, dysphagia, paraesthesias and palpable purpura. Diagnostic studies revealed elevated creatine kinase, diffuse myopathic and sensorimotor axonal neuropathy on electromyography and nerve conduction studies, and inflammatory myopathy on muscle biospsy. Cryoglobulin levels were elevated on two occasions. She responded favourably to cyclophosphamide and high-dose corticosteroids. Cyclophosphamide was continued for 1 year followed by methotrexate. Prednisone was gradually tapered and discontinued 1 year later. She remained in clinical remission after 4 years of follow-up. This case suggests that cryoglobulinaemia should be considered in the differential diagnosis of a patient presenting with inflammatory myopathy.

Variable association of reactive intermediate genes with systemic lupus erythematosus in populations with different African ancestry

OBJECTIVE

Little is known about the genetic etiology of systemic lupus erythematosus (SLE) in individuals of African ancestry, despite its higher prevalence and greater disease severity. Overproduction of nitric oxide (NO) and reactive oxygen species are implicated in the pathogenesis and severity of SLE, making NO synthases and other reactive intermediate-related genes biological candidates for disease susceptibility. We analyzed variation in reactive intermediate genes for association with SLE in 2 populations with African ancestry.

METHODS

A total of 244 single-nucleotide polymorphisms (SNP) from 53 regions were analyzed in non-Gullah African Americans (AA; 1432 cases and 1687 controls) and the genetically more homogeneous Gullah of the Sea Islands of South Carolina (133 cases and 112 controls). Single-marker, haplotype, and 2-locus interaction tests were computed for these populations.

RESULTS

The glutathione reductase gene GSR (rs2253409; p = 0.0014, OR 1.26, 95% CI 1.09-1.44) was the most significant single SNP association in AA. In the Gullah, the NADH dehydrogenase NDUFS4 (rs381575; p = 0.0065, OR 2.10, 95% CI 1.23-3.59) and NO synthase gene NOS1 (rs561712; p = 0.0072, OR 0.62, 95% CI 0.44-0.88) were most strongly associated with SLE. When both populations were analyzed together, GSR remained the most significant effect (rs2253409; p = 0.00072, OR 1.26, 95% CI 1.10-1.44). Haplotype and 2-locus interaction analyses also uncovered different loci in each population.

CONCLUSION

These results suggest distinct patterns of association with SLE in African-derived populations; specific loci may be more strongly associated within select population groups.

Multifocal osteonecrosis in systemic lupus erythematosus: case report and review of the literature

Osteonecrosis is a relatively common comorbidity in systemic lupus erythematosus (SLE), but avascular necrosis in multiple sites is unusual. Multifocal osteonecrosis is defined as osteonecrotic lesions affecting three or more separate anatomic sites. We report a case of a 24-year-old woman diagnosed with SLE when she presented with mucocutaneous, haematological and mild renal manifestations. Initially, she was treated with prednisone and hydroxychloroquine and her condition remained stable. Two years later, she developed severe bilateral pretibial ulcers intractable to immunosuppressive therapy and broad-spectrum antibiotics. MRI of both legs disclosed osteonecrosis of the distal tibia, proximal tibia, distal fibula and talus bilaterally. She had elevated anticardiolipin antibodies for which she was treated with chronic anticoagulation resulting in complete healing of the leg ulcers and no further episodes of osteonecrosis. In addition to this case, we review the demographic, clinical and pharmacological features of 14 cases reported in the literature.

Fine mapping of Xq28: both MECP2 and IRAK1 contribute to risk for systemic lupus erythematosus in multiple ancestral groups

OBJECTIVES

The Xq28 region containing IRAK1 and MECP2 has been identified as a risk locus for systemic lupus erythematosus (SLE) in previous genetic association studies. However, due to the strong linkage disequilibrium between IRAK1 and MECP2, it remains unclear which gene is affected by the underlying causal variant(s) conferring risk of SLE.

METHODS

We fine-mapped ≥136 SNPs in a ∼227 kb region on Xq28, containing IRAK1, MECP2 and seven adjacent genes (L1CAM, AVPR2, ARHGAP4, NAA10, RENBP, HCFC1 and TMEM187), for association with SLE in 15 783 case-control subjects derived from four different ancestral groups.

RESULTS

Multiple SNPs showed strong association with SLE in European Americans, Asians and Hispanics at p<5×10(-8) with consistent association in subjects with African ancestry. Of these, six SNPs located in the TMEM187-IRAK1-MECP2 region captured the underlying causal variant(s) residing in a common risk haplotype shared by all four ancestral groups. Among them, rs1059702 best explained the Xq28 association signals in conditional testings and exhibited the strongest p value in transancestral meta-analysis (p(meta )= 1.3×10(-27), OR=1.43), and thus was considered to be the most likely causal variant. The risk allele of rs1059702 results in the amino acid substitution S196F in IRAK1 and had previously been shown to increase NF-κB activity in vitro. We also found that the homozygous risk genotype of rs1059702 was associated with lower mRNA levels of MECP2, but not IRAK1, in SLE patients (p=0.0012) and healthy controls (p=0.0064).

CONCLUSIONS

These data suggest contributions of both IRAK1 and MECP2 to SLE susceptibility.

MicroRNA-3148 modulates allelic expression of toll-like receptor 7 variant associated with systemic lupus erythematosus

We previously reported that the G allele of rs3853839 at 3′untranslated region (UTR) of Toll-like receptor 7 (TLR7) was associated with elevated transcript expression and increased risk for systemic lupus erythematosus (SLE) in 9,274 Eastern Asians [P = 6.5×10⁻¹⁰, odds ratio (OR) (95%CI) = 1.27 (1.17–1.36)]. Here, we conducted trans-ancestral fine-mapping in 13,339 subjects including European Americans, African Americans, and Amerindian/Hispanics and confirmed rs3853839 as the only variant within the TLR7-TLR8 region exhibiting consistent and independent association with SLE (P_meta = 7.5×10⁻¹¹, OR = 1.24 [1.18–1.34]). The risk G allele was associated with significantly increased levels of TLR7 mRNA and protein in peripheral blood mononuclear cells (PBMCs) and elevated luciferase activity of reporter gene in transfected cells. TLR7 3′UTR sequence bearing the non-risk C allele of rs3853839 matches a predicted binding site of microRNA-3148 (miR-3148), suggesting that this microRNA may regulate TLR7 expression. Indeed, miR-3148 levels were inversely correlated with TLR7 transcript levels in PBMCs from SLE patients and controls (R² = 0.255, P = 0.001). Overexpression of miR-3148 in HEK-293 cells led to significant dose-dependent decrease in luciferase activity for construct driven by TLR7 3′UTR segment bearing the C allele (P = 0.0003). Compared with the G-allele construct, the C-allele construct showed greater than two-fold reduction of luciferase activity in the presence of miR-3148. Reduced modulation by miR-3148 conferred slower degradation of the risk G-allele containing TLR7 transcripts, resulting in elevated levels of gene products. These data establish rs3853839 of TLR7 as a shared risk variant of SLE in 22,613 subjects of Asian, EA, AA, and Amerindian/Hispanic ancestries (P_meta = 2.0×10⁻¹⁹, OR = 1.25 [1.20–1.32]), which confers allelic effect on transcript turnover via differential binding to the epigenetic factor miR-3148.

Systemic lupus erythematosus (SLE) is a debilitating autoimmune disease contributed to by excessive innate immune activation involving toll-like receptors (TLRs, particularly TLR7/8/9) and type I interferon (IFN) signaling pathways. TLR7 responds against RNA–containing nuclear antigens and activates IFN-α pathway, playing a pivotal role in the development of SLE. While a genomic duplication of Tlr7 promotes lupus-like disease in the Y-linked autoimmune accelerator (Yaa) murine model, the lack of common copy number variations at TLR7 in humans led us to identify a functional single nucleotide polymorphism (SNP), rs3853839 at 3′ UTR of the TLR7 gene, associated with SLE susceptibility in Eastern Asians. In this study, we fine-mapped the TLR7-TLR8 region and confirmed rs3853839 exhibiting the strongest association with SLE in European Americans, African Americans, and Amerindian/Hispanics. Individuals carrying the risk G allele of rs3853839 exhibited increased TLR7 expression at the both mRNA and protein level and decreased transcript degradation. MicroRNA-3148 (miR-3148) downregulated the expression of non-risk allele (C) containing transcripts preferentially, suggesting a likely mechanism for increased TLR7 levels in risk-allele carriers. This trans-ancestral mapping provides evidence for the global association with SLE risk at rs3853839, which resides in a microRNA–gene regulatory site affecting TLR7 expression.

Admixture mapping in lupus identifies multiple functional variants within IFIH1 associated with apoptosis, inflammation, and autoantibody production

Systemic lupus erythematosus (SLE) is an inflammatory autoimmune disease with a strong genetic component. African-Americans (AA) are at increased risk of SLE, but the genetic basis of this risk is largely unknown. To identify causal variants in SLE loci in AA, we performed admixture mapping followed by fine mapping in AA and European-Americans (EA). Through genome-wide admixture mapping in AA, we identified a strong SLE susceptibility locus at 2q22–24 (LOD = 6.28), and the admixture signal is associated with the European ancestry (ancestry risk ratio ∼1.5). Large-scale genotypic analysis on 19,726 individuals of African and European ancestry revealed three independently associated variants in the IFIH1 gene: an intronic variant, rs13023380 [P_meta = 5.20×10⁻¹⁴; odds ratio, 95% confidence interval = 0.82 (0.78–0.87)], and two missense variants, rs1990760 (Ala946Thr) [P_meta = 3.08×10⁻⁷; 0.88 (0.84–0.93)] and rs10930046 (Arg460His) [P_dom = 1.16×10⁻⁸; 0.70 (0.62–0.79)]. Both missense variants produced dramatic phenotypic changes in apoptosis and inflammation-related gene expression. We experimentally validated function of the intronic SNP by DNA electrophoresis, protein identification, and in vitro protein binding assays. DNA carrying the intronic risk allele rs13023380 showed reduced binding efficiency to a cellular protein complex including nucleolin and lupus autoantigen Ku70/80, and showed reduced transcriptional activity in vivo. Thus, in SLE patients, genetic susceptibility could create a biochemical imbalance that dysregulates nucleolin, Ku70/80, or other nucleic acid regulatory proteins. This could promote antibody hypermutation and auto-antibody generation, further destabilizing the cellular network. Together with molecular modeling, our results establish a distinct role for IFIH1 in apoptosis, inflammation, and autoantibody production, and explain the molecular basis of these three risk alleles for SLE pathogenesis.

African-Americans (AA) are at increased risk of systemic lupus erythematosus (SLE), but the genetic basis of this risk increase is largely unknown. We used admixture mapping to localize disease-causing genetic variants that differ in frequency across populations. This approach is advantageous for localizing susceptibility genes in recently admixed populations like AA. Our genome-wide admixture scan identified seven admixture signals, and we followed the best signal at 2q22–24 with fine-mapping, imputation-based association analysis and experimental validation. We identified two independent coding variants and a non-coding variant within the IFIH1 gene associated with SLE. Together with molecular modeling, our results establish a distinct role for IFIH1 in apoptosis, inflammation, and autoantibody production, and explain the molecular basis of these three risk alleles for SLE pathogenesis.

Impact of managed care health insurance system for indigent patients with rheumatoid arthritis in Puerto Rico

The aim of this study was to determine the clinical outcome among indigent patients with rheumatoid arthritis (RA) in Puerto Rico receiving their healthcare in a managed care system, as compared with non-indigent patients treated in fee-for-service settings. A cross-sectional study was conducted in 214 Puerto Ricans with RA (per American College of Rheumatology classification criteria). Demographic features, health-related behaviors, cumulative clinical manifestations, disease activity (per disease activity score 28), comorbid conditions, functional status (per Health Assessment Questionnaire), and pharmacologic profile were determined. Data were examined using uni- and multivariable (logistic regression) analyses. The mean (standard deviation (SD)) age of the study population was 56.6 (13.5) years; 180 (84.1 %) were women. The mean (SD) disease duration was 10.8 (9.6) years. Sixty-seven patients were treated in the managed care setting, and 147 patients received their healthcare in fee-for-service settings. In the multivariable analyses, RA patients treated in the managed care setting had more joint deformities, extra-articular manifestations, arterial hypertension, type 2 diabetes mellitus, cardiovascular events, fibromyalgia syndrome, and poorer functional status while having a lower exposure to biological agents than those treated in fee-for-service settings. Efforts should be undertaken to curtail the gap of health disparities among these Hispanic patients in order to improve their long-term outcomes.

Impact of genetic ancestry and sociodemographic status on the clinical expression of systemic lupus erythematosus in American Indian-European populations

OBJECTIVE

American Indian-Europeans, Asians, and African Americans have an excess morbidity from systemic lupus erythematosus (SLE) and a higher prevalence of lupus nephritis than do Caucasians. The aim of this study was to analyze the relationship between genetic ancestry and sociodemographic characteristics and clinical features in a large cohort of American Indian-European SLE patients.

METHODS

A total of 2,116 SLE patients of American Indian-European origin and 4,001 SLE patients of European descent for whom we had clinical data were included in the study. Genotyping of 253 continental ancestry-informative markers was performed on the Illumina platform. Structure and Admixture software were used to determine genetic ancestry proportions of each individual. Logistic regression was used to test the association between genetic ancestry and sociodemographic and clinical characteristics. Odds ratios (ORs) were calculated with 95% confidence intervals (95% CIs).

RESULTS

The average American Indian genetic ancestry of 2,116 SLE patients was 40.7%. American Indian genetic ancestry conferred increased risks of renal involvement (P < 0.0001, OR 3.50 [95% CI 2.63- 4.63]) and early age at onset (P < 0.0001). American Indian ancestry protected against photosensitivity (P < 0.0001, OR 0.58 [95% CI 0.44-0.76]), oral ulcers (P < 0.0001, OR 0.55 [95% CI 0.42-0.72]), and serositis (P < 0.0001, OR 0.56 [95% CI 0.41-0.75]) after adjustment for age, sex, and age at onset. However, age and sex had stronger effects than genetic ancestry on malar rash, discoid rash, arthritis, and neurologic involvement.

CONCLUSION

In general, American Indian genetic ancestry correlates with lower sociodemographic status and increases the risk of developing renal involvement and SLE at an earlier age.

Euforia-induced acute hepatitis in a patient with scleroderma

Euforia, a supplement containing a variety of natural ingredients, is widely used as an antioxidant and anti-inflammatory formula. It is not approved by the US Food and Drug Administration and its side effects are unknown. We report a 45-year-old woman with limited systemic sclerosis who presented with jaundice and marked elevation of serum transaminases. One month before, she started taking Euforia juice. A liver biopsy disclosed submassive hepatocellular necrosis with histopathological changes consistent with toxic hepatitis. The patient's symptoms resolved with cessation of Euforia. Six months later, she persisted with abnormal liver function tests, but these resolved 18 months after discontinuation of Euforia. The mechanism by which Euforia causes liver injury is unknown. Some ingredients contained in this supplement (green tea, Aloe vera, noni and goji) are linked to hepatic injury. To our knowledge, this is the first report of hepatotoxicity associated with Euforia.

Association of two independent functional risk haplotypes in TNIP1 with systemic lupus erythematosus

OBJECTIVE

Systemic lupus erythematosus (SLE) is an autoimmune disease characterized by autoantibody production and altered type I interferon expression. Genetic surveys and genome-wide association studies have identified >30 SLE susceptibility genes. One of these genes, TNIP1, encodes the ABIN1 protein. ABIN1 functions in the immune system by restricting NF-κB signaling. The present study was undertaken to investigate the genetic factors that influence association with SLE in genes that regulate the NF-κB pathway.

METHODS

We analyzed a dense set of genetic markers spanning TNIP1 and TAX1BP1, as well as the TNIP1 homolog TNIP2, in case-control populations of diverse ethnic origins. TNIP1, TNIP2, and TAX1BP1 were fine-mapped in a total of 8,372 SLE cases and 7,492 healthy controls from European-ancestry, African American, Hispanic, East Asian, and African American Gullah populations. Levels of TNIP1 messenger RNA (mRNA) and ABIN1 protein in Epstein-Barr virus-transformed human B cell lines were analyzed by quantitative reverse transcription-polymerase chain reaction and Western blotting, respectively.

RESULTS

We found significant associations between SLE and genetic variants within TNIP1, but not in TNIP2 or TAX1BP1. After resequencing and imputation, we identified 2 independent risk haplotypes within TNIP1 in individuals of European ancestry that were also present in African American and Hispanic populations. Levels of TNIP1 mRNA and ABIN1 protein were reduced among subjects with these haplotypes, suggesting that they harbor hypomorphic functional variants that influence susceptibility to SLE by restricting ABIN1 expression.

CONCLUSION

Our results confirm the association signals between SLE and TNIP1 variants in multiple populations and provide new insight into the mechanism by which TNIP1 variants may contribute to SLE pathogenesis.

Nitrofurantoin-induced microangiopathic haemolytic anaemia and thrombocytopaenia in a patient with systemic lupus erythematosus

Patients with systemic lupus erythematosus (SLE) may develop thrombotic thrombocytopaenic purpura (TTP) or TTP-like illness manifested by microangiopathic haemolytic anaemia (MAHA) and thrombocytopaenia. The distinction between active SLE and TTP is difficult because these entities share similar clinical features. Drug-induced TTP caused by an immune-mediated reaction have been documented for several drugs. Herein, we report a middle-aged Hispanic woman with long-standing SLE, who developed a TTP-like illness characterised by MAHA and thrombocytopaenia after exposure to nitrofurantoin. The patient responded well to plasmapheresis and immunosuppressive therapy and has remained clinically stable after 18&emsp14;months of follow-up. To our knowledge, this is the first case that reports the association between nitrofurantoin and a TTP-like presentation.

A functional haplotype of UBE2L3 confers risk for systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is an autoimmune disease with diverse clinical manifestations characterized by the development of pathogenic autoantibodies manifesting in inflammation of target organs such as the kidneys, skin and joints. Genome-wide association studies have identified genetic variants in the UBE2L3 region that are associated with SLE in subjects of European and Asian ancestry. UBE2L3 encodes an ubiquitin-conjugating enzyme, UBCH7, involved in cell proliferation and immune function. In this study, we sought to further characterize the genetic association in the region of UBE2L3 and use molecular methods to determine the functional effect of the risk haplotype. We identified significant associations between variants in the region of UBE2L3 and SLE in individuals of European and Asian ancestry that exceeded a Bonferroni-corrected threshold (P<1 × 10(-4)). A single risk haplotype was observed in all associated populations. Individuals harboring the risk haplotype display a significant increase in both UBE2L3 mRNA expression (P=0.0004) and UBCH7 protein expression (P=0.0068). The results suggest that variants carried on the SLE-associated UBE2L3 risk haplotype influence autoimmunity by modulating UBCH7 expression.