SLE: challenges and candidates in human disease

Serum proteome and metabolome uncover novel biomarkers for the assessment of disease activity and diagnosing of systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is an autoimmune disease affecting thousands of people. There are still no effective biomarkers for SLE diagnosis and disease activity assessment. We performed proteomics and metabolomics analyses of serum from 121 SLE patients and 106 healthy individuals, and identified 90 proteins and 76 metabolites significantly changed. Several apolipoproteins and the metabolite arachidonic acid were significantly associated with disease activity. Apolipoprotein A-IV (APOA4), LysoPC(16:0), punicic acid and stearidonic acid were correlated with renal function. Random forest model using the significantly changed molecules identified 3 proteins including ATRN, THBS1 and SERPINC1, and 5 metabolites including cholesterol, palmitoleoylethanolamide, octadecanamide, palmitamide and linoleoylethanolamide, as potential biomarkers for SLE diagnosis. Those biomarkers were further validated in an independent cohort with high accuracy (AUC = 0.862 and 0.898 for protein and metabolite biomarkers respectively). This unbiased screening has led to the discovery of novel molecules for SLE disease activity assessment and SLE classification.

Fish oil enhanced the efficacy of low-dose cyclophosphamide regimen for proliferative lupus nephritis: a randomized controlled double-blind trial

Background

Lupus nephritis (LN) is one of the most severe organ that damages the systemic lupus erythematosus (SLE). Cyclophosphamide is one of the main drugs used in the treatment of LN. Fish oil is a general term of all the oily substances in fish, whose main component is omega-3 fatty acid. This study aimed to investigate whether fish oil could be used as an adjunct to low-dose cyclophosphamide in proliferative LN treatment.

Methods

A total of 237 patients with proliferative LN were recruited and randomized into two groups: cyclophosphamide + placebo group and cyclophosphamide + fish oil group. In the cyclophosphamide + placebo group, participants received prednisone + cyclophosphamide + placebo. In the cyclophosphamide + fish oil group, participants received prednisone + cyclophosphamide + fish oil. Before and after treatment, the clinical parameters of the patients in both groups were evaluated.

Results

In the cyclophosphamide + fish oil group, the number of patients achieving complete remission (n = 45, 46.9%) was significantly higher than the cyclophosphamide + placebo group (n = 31, 32.6%). The number of patients achieving no response in the cyclophosphamide + fish oil group (n = 8, 8.3%) was significantly lower than the cyclophosphamide + placebo group (n = 22, 23.2%). Hematuria (P = 0.036), urine protein-creatinine ratio (uPCR) (P = 0.014), estimated glomerular filtration rate (eGFR) (P = 0.027), and renal SLE disease activity index (SLEDAI) (P = 0.009) improved more significantly in the cyclophosphamide + fish oil group. The number of patients with infection (P = 0.04) or urinary tract infection (P = 0.04) in the cyclophosphamide + fish oil group was lower than the cyclophosphamide + placebo group.

Conclusion

In conclusion, the treatment of fish oil in LN patients enhances the efficiency of cyclophosphamide, alleviates nephritis-related parameters, and inhibits infection and urinary tract infection during the treatment. Thus, fish oil may serve as a potential adjuvant drug in the treatment of LN.

Correlation between circulating interleukin-18 level and systemic lupus erythematosus: a meta-analysis

This study is a meta-analysis aimed at pooling reported data and clarifying the association between circulating level of interleukin-18 and systemic lupus erythematosus (SLE). We searched medical databases including Medline/Pubmed, Embase, Scopus, The Cochrane Library, and Web of Science thoroughly to obtain all related articles published before July 15th, 2020. We pooled computed standardized mean difference (SMD) and its 95% confidence interval using STATA 13.0 and exhibited in the form of forest graph. Meta-regression and subgroup analysis were also performed to explore the source of heterogeneity. Publication bias was first evaluated by the symmetry of the funnel plot and then Egger’s linear regression test. Thirty eligible studies from eighteen regions were finally included and the relevant data from these studies were pooled. The analysis results displayed that SLE patients showed a significantly higher level of circulating IL-18 level in comparison with healthy controls (SMD = 1.56, 95% CI [1.20–1.93]; I² = 94.9%, p < 0.01). The conclusion was equally applicable in subgroups divided based on sample type, mean age, disease duration, and testing method. Patients with SLEDAI score higher than five, or who were Asian, White, Arab, or mixed ethnicity had an elevated level of IL-18, while the others didn’t. This meta-analysis has elucidated that compared with healthy people, the circulating level of IL-18 is considerably higher in SLE patients, which indicates the underlying role of IL-18 in SLE pathogenesis.

IMMUNOMODULATORY ROLE OF VITAMIN D: CLINICAL IMPLICATIONS IN INFECTIONS AND AUTOIMMUNE DISORDERS

Vitamin D exerts its well-known effects on bone health and calcium-phosphate homeostasis primarily through the vitamin D receptor signaling pathway. Vitamin D also has several extra-skeletal actions and its deficiency is not only implicated in musculoskeletal disorders, but also cardiovascular disorders, diabetes, neurodegenerative conditions and cancers. There is a growing body of research highlighting the link of vitamin D deficiency and alterations in vitamin D signaling with certain infections and autoimmune disorders although the evidence is inconsistent and inconclusive. Vitamin D has been suggested to play a fundamental role in curbing infections and mitigating autoimmune disease processes. The present review was undertaken to explore the promise of vitamin D as a protective agent and a clinically useful therapeutic adjunct against infections and autoimmune diseases and identify knowledge gaps and limitations of the available data for informing future work. An exhaustive search was conducted in established databases including Google Scholar, PubMed, Science Direct and Springer for articles published on vitamin D, immunity, infection and autoimmune disorders. All relevant articles published in the English language between the year 200 and 2020 were retrieved for writing the review. Although a considerable body of evidence highlighting the potential clinical benefits of vitamin D against the development of various autoimmune conditions and for the prevention of infections has emerged over the last decade, the findings are limited by the lack of appropriately designed randomized controlled trials which are needed to formulate precise clinical recommendations.

Microbiome and Metabolome Analyses Reveal the Disruption of Lipid Metabolism in Systemic Lupus Erythematosus

Systemic lupus erythematosus (SLE) is a systemic autoimmune disease that affects thousands of people worldwide. Recently, alterations in metabolism and gut microbiome have emerged as key regulators of SLE pathogenesis. However, it is not clear about the coordination of gut commensal bacteria and SLE metabolism. Here, by integrating 16S sequencing and metabolomics data, we characterized the gut microbiome and fecal and serum metabolome alterations in patients with SLE. Microbial diversity sequencing revealed gut microflora dysbiosis in SLE patients with significantly increased beta diversity. The metabolomics profiling identified 43 and 55 significantly changed metabolites in serum and feces samples in SLE patients. Notably, lipids accounted for about 65% altered metabolites in serum, highlighted the disruption of lipid metabolism. Integrated correlation analysis provided a link between the gut microbiome and lipid metabolism in patients with SLE, particularly according to regulate the conversion of primary bile acids to secondary bile acids. Overall, our results illustrate the perturbation of the gut microbiome and metabolome in SLE patients which may facilitate the development of new SLE interventions.

Collagen triple helix repeat containing-1: a novel biomarker associated with disease activity in Systemic lupus erythematosus

OBJECTIVE

The objective of this article is to investigate whether the aberrant expression of collagen triple helix repeat containing-1 (CTHRC1) from patients with systemic lupus erythematosus (SLE) could contribute to the pathogenesis of lupus.

METHODS

We divided SLE patients into active groups (Systemic Lupus Erythematosus Disease Activity Index (SLEDAI) score ≥ 6) and inactive groups (SLEDAI score < 6). Serum concentrations of CTHRC1, interferon alpha, interleukin (IL)-28A and IL-28B were determined using an enzyme-linked immunosorbent assay in a group of 40 patients with SLE. Results were compared with those from 23 healthy controls.

RESULTS

Serum CTHRC1 protein levels were higher in patients with SLE compared with healthy controls. Patients with active disease displayed higher CTHRC1 levels compared with those with inactive disease as well. There was a positive association between serum CTHRC1 levels and SLEDAI and erythrocyte sedimentation rate, and a negative correlation with complement 3 and 4. Moreover, serum CTHRC1 levels were higher in SLE patients with arthritis and anemia compared with patients without the above-mentioned manifestations.

CONCLUSIONS

These findings indicate CTHRC1 probably plays an important part in the pathogenesis of SLE, and is positively associated with disease activity, while it also likely refers to the development of arthritis and anemia in SLE. Therefore, CTHRC1 may provide a novel research target and shed new light on the pathogenesis and therapy of SLE.

Growth of B Cell Receptor Microclusters Is Regulated by PIP2 and PIP3 Equilibrium and Dock2 Recruitment and Activation

The growth of B cell receptor (BCR) microclusters upon antigen stimulation drives B cell activation. Here, we show that PI3K-mediated PIP₃ production is required for the growth of BCR microclusters. This growth is likely inhibited by PTEN and dependent on its plasma membrane binding and lipid phosphatase activities. Mechanistically, we find that PIP₃-dependent recruitment and activation of a guanine nucleotide exchange factor, Dock2, is required for the sustained growth of BCR microclusters through remodeling of the F-actin cytoskeleton. As a consequence, Dock2 deficiency significantly disrupts the structure of the B cell immunological synapse. Finally, we find that primary B cells from systemic lupus erythematosus (SLE) patients exhibit more prominent BCR and PI3K microclusters than B cells from healthy controls. These results demonstrate the importance of a PI3K- and PTEN-governed PIP₂ and PIP₃ equilibrium in regulating the activation of B cells through Dock2-controlled growth of BCR microclusters.

A Novel Human Systemic Lupus Erythematosus Model in Humanised Mice

Mouse models have contributed to the bulk of knowledge on Systemic Lupus Erythematosus (SLE). Nevertheless, substantial differences exist between human and mouse immune system. We aimed to establish and characterise a SLE model mediated by human immune system. Injection of pristane into immunodeficient mice reconstituted with human immune system (humanised mice) recapitulated key SLE features, including: production of human anti-nuclear autoantibodies, lupus nephritis, and pulmonary serositis. There was a reduction in the number of human lymphocytes in peripheral blood, resembling lymphopenia in SLE patients. Concurrently, B cells and T cells were systemically hyperactivated, with a relative expansion of CD27⁺ and CD27⁻IgD⁻ memory B cells, increased number of plasmablasts/plasma cells, and accumulation of effector memory T cells. There was also an increased production of human pro-inflammatory cytokines, including: IFN-γ, IL-8, IL-18, MCP-1, and IL-6, suggesting their role in SLE pathogenesis. Increased expression of type I IFN signature genes was also found in human hepatocytes. Altogether, we showed an SLE model that was mediated by human immune system, and which recapitulated key clinical and immunological SLE features. The advancements of humanised mice SLE model would provide an in vivo platform to facilitate translational studies and pre-clinical evaluations of human-specific mechanisms and immunotherapies.

Lack of subclinical myocardial ischaemia in Mexican patients with systemic lupus erythematosus without traditional risk factors for coronary artery disease

The objective of this study was to analyse whether patients with systemic lupus erythematosus (SLE) without traditional risk factors for coronary artery disease (CAD) develop subclinical myocardial ischaemia in the first years after diagnosis. A cross-sectional analysis of a cohort of 200 female SLE patients was conducted. We selected those patients who fulfilled the American College of Rheumatology (ACR) SLE criteria and had no traditional risk factors for CAD, including diabetes mellitus, hypertension, obesity, hyperlipidemia, and smoking. After an initial clinical and laboratory examination, patients were evaluated using a baseline echocardiogram and a dobutamine and atropine stress echocardiogram to search for subclinical myocardial ischaemia. Forty-one patients were included in the study. The mean age at the time of the study was 34.5 ± 9.56 years (mean ± SD). The mean age at diagnosis was 30.3 ± 9.39 years. The mean time from diagnosis was 3.9 ± 3.3 years. Baseline disease activity index (MEX-SLEDAI score) showed that 92.6% of patients had disease activity, although most patients had mild activity. A dobutamine and atropine stress echocardiogram was performed in 40 patients. All 40 patients had negative tests for subclinical myocardial ischaemia. Patients without traditional risk factors for CAD do not have an increased risk for subclinical myocardial ischaemia in the first years after diagnosis. A longitudinal follow-up study of these patients is needed to confirm our findings and assess if additional non-traditional risk factors for CAD increase the risk for myocardial ischaemia. Lupus (2007) 16, 298—301.

Immune Response Modulation by Vitamin D: Role in Systemic Lupus Erythematosus

Vitamin D plays key roles as a natural immune modulator and has been implicated in the pathophysiology of autoimmune diseases, including systemic lupus erythematosus (SLE). This review presents a summary and analysis of the recent literature regarding immunoregulatory effects of vitamin D as well as its importance in SLE development, clinical severity, and possible effects of supplementation in disease treatment.

Immune sensing of nucleic acids in inflammatory skin diseases

Endosomal and cytosolic nucleic acid receptors are important immune sensors required for the detection of infecting or replicating viruses. The intracellular location of these receptors allows viral recognition and, at the same time, avoids unnecessary immune activation to self-nucleic acids that are continuously released by dying host cells. Recent evidence, however, indicates that endogenous factors such as anti-microbial peptides have the ability to break this protective mechanism. Here, we discuss these factors and illustrate how they drive inflammatory responses by promoting immune recognition of self-nucleic acids in skin wounds and inflammatory skin diseases such as psoriasis and lupus.

Characterization of Novel PI3Kδ Inhibitors as Potential Therapeutics for SLE and Lupus Nephritis in Pre-Clinical Studies

SLE is a complex autoimmune inflammatory disease characterized by pathogenic autoantibody production as a consequence of uncontrolled T–B cell activity and immune-complex deposition in various organs, including kidney, leading to tissue damage and function loss. There is a high unmet need for better treatment options other than corticosteroids and immunosuppressants. Phosphoinositol-3 kinase δ (PI3Kδ) is a promising target in this respect as it is essential in mediating B- and T-cell function in mouse and human. We report the identification of selective PI3Kδ inhibitors that blocked B-, T-, and plasmacytoid dendritic cell activities in human peripheral blood and in primary cell co-cultures (BioMAP^®) without detecting signs of undesired toxicity. In an IFNα-accelerated mouse SLE model, our PI3Kδ inhibitors blocked nephritis development, whether administered at the onset of autoantibody appearance or the onset of proteinuria. Disease amelioration correlated with normalized immune cell numbers in the spleen, reduced immune-complex deposition as well as reduced inflammation, fibrosis, and tissue damage in the kidney. Improvements were similar to those achieved with a frequently prescribed drug for lupus nephritis, the potent immunosuppressant mycophenolate mofetil. Finally, we established a pharmacodynamics/pharmacokinetic/efficacy model that revealed that a sustained PI3Kδ inhibition of 50% is sufficient to achieve full efficacy in our disease model. These data demonstrate the therapeutic potential of PI3Kδ inhibitors in SLE and lupus nephritis.

Complement C1q production by osteoclasts and its regulation of osteoclast development

C1q deficiency is the strongest known risk factor for SLE (systemic lupus erythematosus) but its endogenous cellular origin remains limitedly understood. In the present study we investigate the production of C1q by both cultured and endogenous bone osteoclasts. Blood monocytes were cultured with RANKL (receptor activator of nuclear factor κB ligand) and M-CSF (macrophage colony-stimulating factor) to generate osteoclasts and these cells expressed C1Q mRNA and also secreted C1q protein. Intracellular C1q was detectable in developing osteoclasts at day 3 by Western blotting and was also detectable by flow cytometry. By immunofluorescence microscopy, C1q was preferentially detected in immature osteoclasts. By multiple detection methods, C1q expression was markedly increased after IFNγ (interferon γ) treatment. By immunohistochemistry, C1q was also detected in endogenous bone osteoclasts. When osteoclasts were cultured on immobilized C1q, these cells exhibited 2-7-fold increases in the expression of signature osteoclast genes [TRAP (tartrate-resistant acid phosphatase), cathepsin K, calcitonin receptor, carbonic anhydrase II and NFATc1 (nuclear factor of activated T-cells, cytoplasmic, calcineurin-dependent 1)], suggesting an osteoclastogenic capability. This is the first report of C1q production by osteoclasts. Its ability to enhance osteoclast development implies reduced osteoclastogenesis in patients with SLE as they often experience decreased C1q levels. This is consistent with the non-erosive nature of lupus arthritis.

Targeting the BLyS-APRIL signaling pathway in SLE

The B lymphocyte stimulator (BLyS)-A PRoliferation-Inducing Ligand (APRIL) signaling pathway has an important role in the selection, maturation and survival of B cells and plays a significant role in the pathogenesis of systemic lupus erythematosus (SLE). The inhibition of BLyS, a survival factor for transitional and mature B cells, has recently proven to be successful in large phase III clinical trials that led to the approval of an anti-BLyS monoclonal antibody (belimumab) for the treatment of SLE. Yet, there is currently a need to both understand better the mechanisms of action of belimumab in SLE and better define the subsets of patients that are more likely to respond to the drug.

Correlation of circulating glucocorticoid-induced TNFR-related protein ligand levels with disease activity in patients with systemic lupus erythematosus

The aim of this paper is to investigate the correlation of glucocorticoid-induced tumor necrosis factor receptor- (TNFR-) related protein ligand (GITRL) with disease activity and organ involvement in patients with systemic lupus erythematosus (SLE). Serum GITRL levels were measured in 58 patients with SLE and 30 healthy controls matched for age and sex. Patients were assessed for clinical and laboratory variables. Correlations of serum GITRL levels with SLEDAI, laboratory values, and clinical manifestations were assessed. Serum GITRL levels were determined by ELISA. Serum GITRL levels were markedly increased in patients with SLE compared with healthy controls (mean 401.3 ng/mL and 36.59 ng/mL, resp.; P < 0.0001). SLE patients with active disease showed higher serum GITRL levels compared to those with inactive disease (mean 403.3 ng/mL and 136.3 ng/mL, resp; P = 0.0043) as well as normal controls (36.59 ng/mL; P < 0.0001). Serum GITRL levels were positively correlated with SLEDAI, titers of anti-dsDNA antibody, erythrocyte sedimentation rate (ESR), and IgM and negatively correlated with complement3 (C3). Serum GITRL levels were higher in SLE patients with renal involvement and vasculitis compared with patients without the above-mentioned manifestations.

Carabin deficiency in B cells increases BCR-TLR9 costimulation-induced autoimmunity

The mechanisms behind flares of human autoimmune diseases in general, and of systemic lupus in particular, are poorly understood. The present scenario proposes that predisposing gene defects favour clinical flares under the influence of external stimuli. Here, we show that Carabin is low in B cells of (NZB × NZW) F1 mice (murine SLE model) long before the disease onset, and is low in B cells of lupus patients during the inactive phases of the disease. Using knock-out and B-cell-conditional knock-out murine models, we identify Carabin as a new negative regulator of B-cell function, whose deficiency in B cells speeds up early B-cell responses and makes the mice more susceptible to anti-dsDNA production and renal lupus flare after stimulation with a Toll-like Receptor 9 agonist, CpG-DNA. Finally, in vitro analysis of NFκB activation and Erk phosphorylation in TLR9- and B-cell receptor (BCR)-stimulated Carabin-deficient B cells strongly suggests how the internal defect synergizes with the external stimulus and proposes Carabin as a natural inhibitor of the potentially dangerous crosstalk between BCR and TLR9 pathways in self-reactive B cells.

n-3 fatty acids prevent impairment of neurogenesis and synaptic plasticity in B-cell activating factor (BAFF) transgenic mice

OBJECTIVE

Autoimmune-prone B-cell activating factor transgenic mice, a mouse model of systemic lupus erythematosus and Sjögren's syndrome exhibit neuroinflammation, anxiety-like phenotype, deficit in adult hippocampal neurogenesis and impaired neurogenesis-dependent and neurogenesis-independent dentate gyrus long-term potentiation. Given that n-3 polyunsaturated fatty acids regulate hippocampal plasticity and inflammatory responses, we investigated whether n-3 polyunsaturated fatty acids-enriched diet might prevent age-dependent hippocampal changes in B-cell activating factor transgenic mice.

METHODS

B-cell activating factor transgenic mice were fed for 12 weeks with either n-3 polyunsaturated fatty acids-enriched or control diet and we tested the effect of this dietary supplementation on hippocampal inflammation, progenitor cell proliferation and neurogenesis-dependent and neurogenesis-independent long-term potentiation.

RESULTS

Dietary supplementation with n-3 polyunsaturated fatty acids significantly decreased hippocampal microglial activation and increased the density of bromodeoxyuridine and doublecortin-positive newly-formed cells in the subventricular zone of hippocampus. Furthermore, B-cell activating factor transgenic mice fed with n-3 polyunsaturated fatty acids-enriched diet displayed normal long-term potentiation at the medial perforant pathway/dentate gyrus connections.

CONCLUSIONS

The results indicate that n-3 fatty acids prevent neuroinflammation and deficits of hippocampal plasticity in B-cell activating factor transgenic mice and suggest that increased n-3 fatty acids intake might represent a potential therapeutic option to prevent neuropsychiatric symptoms associated with autoimmune diseases.

Interferon-lambda1 induces peripheral blood mononuclear cell-derived chemokines secretion in patients with systemic lupus erythematosus: its correlation with disease activity

INTRODUCTION

Systemic lupus erythematosus (SLE) is an autoimmune disease involving multiple organ systems. Previous studies have suggested that interferon-lambda 1 (IFN-λ1), a type III interferon, plays an immunomodulatory role. In this study we investigated its role in SLE, including its correlation with disease activity, organ disorder and production of chemokines.

METHODS

We determined levels of IFN-λ1 mRNA in peripheral blood mononuclear cells (PBMC) and serum protein levels in patients with SLE using real-time polymerase chain reaction (real-time PCR) and enzyme-linked immunoassay (ELISA). Further, we detected the concentration of IFN-inducible protein-10 (IP-10), monokine induced by IFN-γ (MIG) and interleukin-8 (IL-8) secreted by PBMC under the stimulation of IFN-λ1 using ELISA.

RESULTS

IFN-λ1 mRNA and serum protein levels were higher in patients with SLE compared with healthy controls. Patients with active disease showed higher IFN-λ1 mRNA and serum protein levels compared with those with inactive disease as well. Serum IFN-λ1 levels were positively correlated with Systemic Lupus Erythematosus Disease Activity Index (SLEDAI), anti-dsDNA antibody, C-reactive protein (CRP) and negatively correlated with complement 3. Serum IFN-λ1 levels were higher in SLE patients with renal involvement and arthritis compared with patients without the above-mentioned manifestations. IFN-λ1 with different concentrations displayed different effects on the secretion of the chemokines IP-10, MIG and IL-8.

CONCLUSIONS

These findings indicate that IFN-λ1 is probably involved in the renal disorder and arthritis progression of SLE and associated with disease activity. Moreover, it probably plays an important role in the pathogenesis of SLE by stimulating secretion of the chemokines IP-10, MIG and IL-8. Thus, IFN-λ1 may provide a novel research target for the pathogenesis and therapy of SLE.

C1q regulation of dendritic cell development from monocytes with distinct cytokine production and T cell stimulation

The causative association of complement C1q deficiency with systemic lupus erythematosus (SLE), which inevitably involves the breakdown of tolerance, remains poorly explained. Its non-hepatic, macrophage and dendritic cell (DC) origin may be highly relevant. In tissues, C1q is produced by DCs and macrophages which deposits around these cells and we ask whether this pericellular form of C1q regulates DC development from monocytes. DCs cultured on immobilized C1q (C1q-DCs) show similar MHC, CD40, CD80, CD86, CD83 and CCR7 expression as normal DCs, but these cells exhibit increased phagocytosis of apoptotic cells and elevated IL-10 but reduced IL-12 and IL-23 production. Intracellularly, C1q-DCs exhibit increased ERK, p38 and p70S6 kinase activity. By mixed leukocyte reaction, C1q-DCs show reduced Th1 and Th17 induction from allogeneic CD4(+) T cells. LPS and IFNγ, which cause normal DCs to induce increased CD25 expression on CD4(+) T cells, attenuate C1q-DC induction of CD25. These imply that the DC pericellular C1q may induce tolerogenic properties in developing DCs.

Novel peptides as potential treatment of systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is an autoimmune disease characterized by a loss of immunologic tolerance, production of auto-antibodies, and inflammatory damage in multiple organs. We have tested the effect of anti-inflammatory peptide, a H2A histone fragment, termed IIIM1, on MRL/lpr mice, animal model of SLE. Oral administration of IIIM1 at early stage of disease caused reduction in proteinuria and serum anti-dsDNA antibodies. Starting the treatment at advanced stage of disease resulted in prolonged animal survival, decreased lymphadenosis and reduced levels of pathogenic or abnormal double negative CD4−CD8− cells and B220+ cells in lymph nodes and spleen. We discovered that IIIM1 induces the production of an additional peptide, a fragment of alpha-1-antitrypsin, termed UBE. A relatively low dose (1 µg/kg) of UBE reduced proteinuria and hematuria in MRL/lpr mice. The beneficial effect of the peptide was corroborated by histological examination. Furthermore a significant reduction in serum IL17, IL12 and anti dsDNA antibodies was observed in the UBE-treated mice. Isolated CD4 cells incubated with the peptide showed a similar cytokine profile. Decreased levels of double negative CD4−CD8− and B220+ cells were determined in lymph organs of UBE-treated animals. The beneficial effects of both UBE and IIIM1 suggest these peptides as potential drugs for SLE.

Cerebral arterial stenoses and stroke: novel features of Aicardi-Goutières syndrome caused by the Arg164X mutation in SAMHD1 are associated with altered cytokine expression

Aicardi-Goutières syndrome (AGS) is a rare inborn multisystemic disease, resembling intrauterine viral infection and resulting in psychomotor retardation, spasticity and chilblain-like skin lesions. Diagnostic criteria include intracerebral calcifications and elevated interferon-alpha and pterin levels in cerebrospinal fluid (CSF). We report on four adult siblings with unknown neurodegenerative disease presenting with cerebrovascular stenoses, stroke and glaucoma in childhood, two of whom died at the age of 40 and 29 years. Genome-wide homozygosity mapping identified 170 candidate genes embedded in a common haplotype of 8Mb on chromosome 20q11-13. Next generation sequencing of the entire region identified the c.490C>T (p.Arg164X) mutation in SAMHD1, a gene most recently described in AGS, on both alleles in all affected siblings. Clinical diagnosis of AGS was then confirmed by demonstrating intracerebral calcifications on cranial computed tomography in all siblings and elevated pterin levels in CSF in three of them. In patient fibroblasts, lack of SAMHD1 protein expression was associated with increased basal expression of IL8, while stimulated expression of IFNB1 was reduced. We conclude that cerebrovascular stenoses and stroke associated with the Arg164X mutation in SAMHD1 extend the phenotypic spectrum of AGS. The observed vascular changes most likely reflect a vasculitis caused by dysregulated inflammatory stress response. © 2010 Wiley-Liss, Inc.

Spleen tyrosine kinases: biology, therapeutic targets and drugs

Spleen tyrosine kinase (Syk) is an intriguing protein tyrosine kinase involved in signal transduction in a variety of cell types, and its aberrant regulation is associated with different allergic disorders and antibody-mediated autoimmune diseases such as rheumatoid arthritis, asthma and allergic rhinitis. Syk also plays an important part in the uncontrolled growth of tumor cells, particularly B cells. For these reasons, Syk is considered one of the most interesting biological targets of the last decade, as proved by the great number of papers and patents published, and the possibility of treating these pathologies by means of Syk kinase inhibitors has led to a great interest from the pharmaceutical and biotech industry.

Anti-DNA antibody induction of protein kinase C phosphorylation and fibronectin synthesis in human and murine lupus and the effect of mycophenolic acid

OBJECTIVE

To examine fibronectin (FN) expression in human lupus nephritis and the effect of anti-DNA antibodies on transforming growth factor beta1 (TGFbeta1) and FN synthesis in cultured human mesangial cells. The effects of mycophenolic acid (MPA) on this pathway, and the effects of mycophenolate mofetil (MMF) treatment in (NZB x NZW)F(1)/J mice were also studied.

METHODS

Immunohistochemical analyses of renal biopsy samples from patients with active diffuse proliferative lupus nephritis were performed. Cultured human mesangial cells were incubated with human polyclonal anti-DNA antibodies, with or without MPA. (NZB x NZW)F(1)/J mice with active nephritis were randomized to receive either MMF (100 mg/kg/day) or vehicle treatment for 12 weeks.

RESULTS

Glomerular FN expression was increased in patients with lupus nephritis, and it colocalized with IgG deposition. Anti-DNA antibodies induced protein kinase Calpha (PKCalpha), PKCbetaI, and PKCbetaII activation, increased levels of bioactive TGFbeta1, and increased FN synthesis in human mesangial cells (P < 0.001 for each comparison versus control conditions). Pretreatment of anti-DNA antibodies with exogenous DNA reduced their cellular binding and abrogated their induction of TGFbeta1 and FN synthesis. Inhibition of PKC activation in human mesangial cells prior to anti-DNA antibody stimulation had no effect on cell proliferation, but resulted in significantly reduced antibody-mediated TGFbeta1 secretion and FN synthesis. MPA treatment down-regulated PKCalpha, PKCbetaI, and PKCbetaII phosphorylation, reduced levels of TGFbeta1 bioactivation, and decreased FN synthesis and deposition into the extracellular matrix. MMF treatment in (NZB x NZW)F(1)/J mice resulted in a reduction in glomerular IgG deposition, PKC activation, and FN expression, as well as an amelioration of proteinuria.

CONCLUSION

Human polyclonal anti-DNA antibodies induce TGFbeta1 and FN synthesis in human mesangial cells through PKC activation, which is inhibited by MPA.

Suppression of murine SLE by oral anti-CD3: inducible CD4+CD25-LAP+ regulatory T cells control the expansion of IL-17+ follicular helper T cells

Lupus is an antibody-mediated autoimmune disease. The production of pathogenic, class switched and affinity maturated autoantibodies in lupus is dependent on T cell help. A potential mechanism of disease pathogenesis is a lack of control of pathogenic T helper cells by regulatory T cells in lupus. It has been repeatedly shown that the naturally occurring CD4+CD25+ regulatory T cells in lupus prone mice and patients with SLE are defective both in frequency and function. Thus, the generation of inducible regulatory T cells that can control T cell help for autoantibody production is a potential avenue for the treatment of SLE. We have found that oral administration of anti-CD3 monoclonal antibody attenuated lupus development and arrested on-going disease in lupus prone SNF1 mice. Oral anti-CD3 induces a CD4+CD25-LAP+ regulatory T cell that secrets high levels of TGF-beta and suppresses in vitro in TFG-beta-dependent fashion. Animals treated with oral anti-CD3 had less glomerulonephritis and diminished levels of anti-dsDNA autoantibodies. Oral anti-CD3 led to a downregulation of IL-17+CD4+ICOS-CXCR5+ follicular helper T cells, CD138+ plasma cells and CD73+ mature memory B cells. Our results show that oral anti-CD3 induces CD4+CD25-LAP+ regulatory T cells that suppress lupus in mice and is associated with downregulation of T cell help for autoantibody production.

Association study between B- and T-lymphocyte attenuator gene and type 1 diabetes mellitus or systemic lupus erythematosus in the Japanese population

This study is to elucidate whether the B- and T-lymphocyte attenuator (BTLA) gene is a new susceptibility gene for the development of type 1 diabetes (T1D) and systemic lupus erythematosus (SLE). As a result, this study did not find any genetic contribution of the BTLA gene to the development of T1D and SLE in Japanese population.

Risk factors of vertebral fractures in women with systemic lupus erythematosus

The aim of the current study was to analyze the role of traditional and systemic lupus erythematosus (SLE)-related risk factors in the development of vertebral fractures. A cross-sectional study was performed in women with SLE attending a single center. A vertebral fracture was defined as a reduction of at least 20% of vertebral body height. Two hundred ten patients were studied, with median age of 43 years and median disease duration of 72 months. Osteopenia was present in 50.3% of patients and osteoporosis in 17.4%. At least one vertebral fracture was detected in 26.1%. Patients with vertebral fractures had a higher mean age (50 +/- 14 vs. 41 +/- 13.2 years, p = 0.001), disease damage (57.1% vs. 34.4%, p = 0.001), lower bone mineral density (BMD) at the total hip (0.902 +/- 0.160 vs. 982 +/- 0.137 g/cm(2), p = 0.002), and postmenopausal status (61.9% vs. 45.3%, p = 0.048). Stepwise logistic regression analysis revealed that only age (p = 0.001) and low BMD at the total hip (p = 0.007) remained as significant factors for the presence of vertebral fracture. The high prevalence of vertebral fractures in the relatively young population implies that more attention must be paid to detect and treat vertebral fractures.

T cell-independent spontaneous loss of tolerance by anti-double-stranded DNA B cells in C57BL/6 mice

Systemic lupus erythematosus is characterized by loss of tolerance to DNA and other nuclear Ags. To understand the role of T cells in the breaking of tolerance, an anti-DNA site-specific transgenic model of spontaneous lupus, B6x56R, was studied. T cells were eliminated by crossing B6x56R with CD4(-/)(-) or TCRbeta(-/-)delta(-/-) mice, and the effects on anti-dsDNA serum levels, numbers of anti-dsDNA Ab-secreting cells, and isotypes of anti-dsDNA were analyzed. In addition, the development and activation of B cells in these mice were examined. Surprisingly, the presence of T cells made little difference in the development and character of the serum anti-dsDNA Ab in B6x56R mice. At 1 mo of age, anti-dsDNA Abs were somewhat lower in mice deficient in alphabeta and gammadelta T cells. Levels of Abs later were not affected by T cells, nor was autoantibody class switching. B cell activation was somewhat diminished in T cell-deficient mice. Thus, in the B6 background, the presence of an anti-dsDNA transgene led the production of autoantibodies with a specificity and isotype characteristic of murine systemic lupus erythematosus with little influence from T cells. TLR9 also did not appear to play a role. Although we do not yet understand the mechanism of this failure of immunoregulation, these results suggest that similar processes may influence autoimmunity associated with clinical disease.

Apoptosis-related genes change their expression with age and hearing loss in the mouse cochlea

To understand possible causative roles of apoptosis gene regulation in age-related hearing loss (presbycusis), apoptotic gene expression patterns in the CBA mouse cochlea of four different age and hearing loss groups were compared, using GeneChip and real-time (qPCR) microarrays. GeneChip transcriptional expression patterns of 318 apoptosis-related genes were analyzed. Thirty eight probes (35 genes) showed significant differences in expression. The significant gene families include Caspases, B-cell leukemia/lymphoma2 family, P53, Calpains, Mitogen activated protein kinase family, Jun oncogene, Nuclear factor of kappa light chain gene enhancer in B-cells inhibitor-related and tumor necrosis factor-related genes. The GeneChip results of 31 genes were validated using the new TaqMan Low Density Array (TLDA). Eight genes showed highly correlated results with the GeneChip data. These genes are: activating transcription factor3, B-cell leukemia/lymphoma2, Bcl2-like1, caspase4 apoptosis-related cysteine protease 4, Calpain2, dual specificity phosphatase9, tumor necrosis factor receptor superfamily member12a, and Tumor necrosis factor superfamily member13b, suggesting they may play critical roles in inner ear aging.

Modulation of nuclear factor-kappaB activity can influence the susceptibility to systemic lupus erythematosus

Autoimmune diseases, such as systemic lupus erythematosus (SLE), result from deficiencies in self-antigen tolerance processes, which require regulated dendritic cell (DC) function. In this study we evaluated the phenotype of DCs during the onset of SLE in a mouse model, in which deletion of the inhibitory receptor FcgammaRIIb leads to the production of anti-nuclear antibodies and glomerulonephritis. Splenic DCs from FcgammaRIIb-deficient mice suffering from SLE showed increased expression of co-stimulatory molecules. Furthermore, diseased mice showed an altered function of the nuclear factor-kappaB (NF-kappaB) transcription factor, which is involved in DC maturation. Compared with healthy animals, expression of the inhibitory molecule IkappaB-alpha was significantly decreased in mice suffering from SLE. Consistently, pharmacological inhibition of NF-kappaB activity in FcgammaRIIb-deficient mice led to reduced susceptibility to SLE and prevented symptoms, such as anti-nuclear antibodies and kidney damage. Our data suggest that the occurrence of SLE is significantly influenced by alterations of NF-kappaB function, which can be considered as a new therapeutic target for this disease.

Time to seizure occurrence and damage in PROFILE, a multi-ethnic systemic lupus erythematosus cohort

The objective of this study was to determine risk factors predicting seizures and damage caused by seizures in a multi-ethnic systemic lupus erythematosus cohort (PROFILE) that includes systemic lupus erythematosus patients (n = 1295) from five different US institutions. Only patients with seizures after systemic lupus erythematosus diagnosis (incident) were included in the analyses of clinical seizures (80/1295, 6.2%), but all patients (prevalent and incident) were included in the analyses of damage caused by seizures (51/1295, 3.9%). We examined socioeconomic-demographic, clinical, and genetic variables predictive of clinical seizures and damage from seizures by Cox proportional hazard ratios (HR) and 95% confidence intervals (CI). Independent predictors of a shorter time to the occurrence of clinical seizures were younger age (HR = 1.0; 95% CI 0.9-1.0), having Hispanic-Texan ethnicity (HR = 2.7; 95% CI 1.3-5.7) or African-American ethnicity (HR = 1.8; 95% CI 1.0-3.1), and the previous occurrence of a cerebrovascular accident (HR = 3.3; 95% CI 1.6-7.1) or an episode of psychosis (HR = 2.4; 95% CI 1.1-5.0), whereas the previous occurrence of photosensitivity (HR = 0.5; 95% CI 0.3-0.9) was the only independent predictor of a longer time to the occurrence of clinical seizures. Independent predictors of a shorter time to the occurrence of damage caused by seizures were younger age (HR = 1.0; 95% CI 0.9-1.0), male gender (HR = 2.4; 95% CI 1.1-5.4), and the occurrence of a previous cerebrovascular accident (HR = 2.7; 95% CI 1.0-7.0) or an episode of psychosis (HR = 4.7; 95% CI 2.3-9.9). No allele from the candidate genes examined (HLA-DRB1, HLA-DQB1, FCGR2A, FCGR3A, or FCG3B) predicted clinical seizures or damage caused by seizures.

Successful treatment of amegakaryocytic thrombocytopenia with anti-CD20 antibody (rituximab) in a patient with systemic lupus erythematosus

Amegakaryocytic thrombocytopenia is an extremely rare disorder in systemic lupus erythematosus, and its mechanism and treatment are still largely unknown. We describe a 42-year-old woman with systemic lupus erythematosus who presented various clinical manifestations of life-threatening amegakaryocytic thrombocytopenia (10,000 platelets/mm3 with a marked decrease of megakaryocytes in the bone marrow), proteinuria, psychosis, refractory chylothorax, ascites, and type II diabetes caused by the anti-insulin receptor autoantibody. She was initially treated with prednisolone (25-50 mg/day) and cyclosporine A (200 mg/day) without any improvement in severe thrombocytopenia. However, her clinical symptoms, including platelet counts, dramatically improved, with a concurrent decrease in the anti-c-Mpl antibody, an autoantibody against the thrombopoietin receptor, after a subsequent treatment with rituximab (375 mg/m2 intravenously, weekly, for two consecutive weeks). Our case suggested that amegakaryocytic thrombocytopenia in patients with systemic lupus erythematosus might be mediated by the anti-c-Mpl antibody and could be treated with rituximab through elimination of pathogenic B cells producing autoimmune antibodies.

Risks factors for low bone mineral density in pre-menopausal Mexican women with systemic lupus erythematosus

The aim of this study was to determine the prevalence and risk factors for low bone mineral density (BMD) in women with systemic lupus erythematosus (SLE). A cross-sectional study was conducted among 100 pre-menopausal patients with SLE. Patients were evaluated using a questionnaire about the following variables: age, disease duration, disease activity, chronic disease damage, cumulative corticosteroid dose, and history of fracture. Lumbar spine and hip measurements of BMD were performed by dual absorptiometry. Univariate and multivariate statistical analyses were used to assess the relationship between risk factors and BMD. The mean age was 32.8 +/- 8.7 years, and the median duration of SLE was 73.2 +/- 65 months. The mean cumulative corticosteroid dose was 20.0 +/- 21.3 g. The mean BMD was 1.09 +/- .18 g/cm(2) in the lumbar spine and 1.0 +/- .14 g/cm(2) in the hip. Osteopenia was present in 40% of patients and osteoporosis in 5%. In the multiple regression analysis, low BMD in the lumbar spine was associated with chronic disease damage and low body mass index (BMI). Low BMD in the hip was associated with cumulative corticosteroid dose and low BMI. Chronic disease damage, low BMI, and cumulative corticosteroid dose are risks factors for low BMD in pre-menopausal SLE patients. Osteopenia was found in 40% of patients, while osteoporosis was found in only 5%.

Ultrastructure of myoepithelial cells as a target cell in sialoadenitis of submandibular glands of lupus-prone female NZBxNZWF1 mice

The changes of myoepithelial cells of sialoadenitis in submandibular glands in lupus-prone female NZB x NZWF1 (B/WF1) mice, a model for human secondary Sjögren's syndrome (sSS), were examined ultrastructurally. Inflammatory foci consisting of mainly lymphoid cells (lymphocytes and plasma cells) in the interlobular interstitium began to develop from 18 weeks of ages, and those were found within acini from the age of 25 weeks. These were paralleled with the production of anti-double-stranded deoxyribonucleic acid and anti-Ro/SS-A antibodies with age. Infiltrated lymphoid cells consisted of CD4+ T cells and Ig+ (or IgG2a+) cells. Electron microscopy revealed destruction of myoepithelial cells with lysis of basement membranes contacted with either lymphocytes or plasma cells. These led to the destruction (degeneration and necrosis) of the epithelium in striated and intercalated ducts and acinar epithelium. Further destruction of those cells occurred by the invasion of lymphocytes into the epithelial layers. Small numbers of apoptotic myoepithelium and duct epithelium from the age of 25 to 36 weeks and an increase of those cells in survived mice at 44 weeks of age were observed. The present study suggests that the myoepithelium may be one of the target cells and that the destruction of myoepithelial cells by infiltrated lymphoid cells may precede the destruction of acinar ducts and epithelium in sialoadenitis in sSS.

Curcumin and autoimmune disease

The immune system has evolved to protect the host from microbial infection; nevertheless, a breakdown in the immune system often results in infection, cancer, and autoimmune diseases. Multiple sclerosis, rheumatoid arthritis, type 1 diabetes, inflammatory bowel disease, myocarditis, thyroiditis, uveitis, systemic lupus erythromatosis, and myasthenia gravis are organ-specific autoimmune diseases that afflict more than 5% of the population worldwide. Although the etiology is not known and a cure is still wanting, the use of herbal and dietary supplements is on the rise in patients with autoimmune diseases, mainly because they are effective, inexpensive, and relatively safe. Curcumin is a polyphenolic compound isolated from the rhizome of the plant Curcuma longa that has traditionally been used for pain and wound-healing. Recent studies have shown that curcumin ameliorates multiple sclerosis, rheumatoid arthritis, psoriasis, and inflammatory bowel disease in human or animal models. Curcumin inhibits these autoimmune diseases by regulating inflammatory cytokines such as IL-1beta, IL-6, IL-12, TNF-alpha and IFN-gamma and associated JAK-STAT, AP-1, and NF-kappaB signaling pathways in immune cells. Although the beneficial effects of nutraceuticals are traditionally achieved through dietary consumption at low levels for long periods of time, the use of purified active compounds such as curcumin at higher doses for therapeutic purposes needs extreme caution. A precise understanding of effective dose, safe regiment, and mechanism of action is required for the use of curcumin in the treatment of human autoimmune diseases.

Opposed independent effects and epistasis in the complex association of IRF5 to SLE

Genetic variation in the interferon regulatory factor 5 (IRF5) gene affects systemic lupus erythematosus (SLE) susceptibility. However, association is complex and incompletely defined. We obtained fourteen European sample collections with a total of 1383 SLE patients and 1614 controls to better define the role of the different IRF5 variants. Eleven polymorphisms were studied, including nine tag single nucleotide polymorphisms (SNPs) and two extra functional polymorphisms. Two tag SNPs showed independent and opposed associations: susceptibility (rs10488631, P<10(-17)) and protection (rs729302, P<10(-6)). Haplotype analyses showed that the susceptibility haplotype, identified by the minor allele of rs10488631, can be due to epistasis between three IRF5 functional polymorphisms. These polymorphisms determine increased mRNA expression, a splice variant with a different exon 1 and a longer proline-rich region in exon 6. This result is striking as none of the three polymorphisms had an independent effect on their own. Protection was independent of these polymorphisms and seemed to reside in the 5' side of the gene. In conclusion, our results help to understand the role of the IRF5 locus in SLE susceptibility by clearly separating protection from susceptibility as caused by independent polymorphisms. In addition, we have found evidence for epistasis between known functional polymorphisms for the susceptibility effect.

Time to renal disease and end-stage renal disease in PROFILE: a multiethnic lupus cohort

BACKGROUND

Renal involvement is a serious manifestation of systemic lupus erythematosus (SLE); it may portend a poor prognosis as it may lead to end-stage renal disease (ESRD). The purpose of this study was to determine the factors predicting the development of renal involvement and its progression to ESRD in a multi-ethnic SLE cohort (PROFILE).

METHODS AND FINDINGS

PROFILE includes SLE patients from five different United States institutions. We examined at baseline the socioeconomic-demographic, clinical, and genetic variables associated with the development of renal involvement and its progression to ESRD by univariable and multivariable Cox proportional hazards regression analyses. Analyses of onset of renal involvement included only patients with renal involvement after SLE diagnosis (n = 229). Analyses of ESRD included all patients, regardless of whether renal involvement occurred before, at, or after SLE diagnosis (34 of 438 patients). In addition, we performed a multivariable logistic regression analysis of the variables associated with the development of renal involvement at any time during the course of SLE. In the time-dependent multivariable analysis, patients developing renal involvement were more likely to have more American College of Rheumatology criteria for SLE, and to be younger, hypertensive, and of African-American or Hispanic (from Texas) ethnicity. Alternative regression models were consistent with these results. In addition to greater accrued disease damage (renal damage excluded), younger age, and Hispanic ethnicity (from Texas), homozygosity for the valine allele of FcgammaRIIIa (FCGR3A*GG) was a significant predictor of ESRD. Results from the multivariable logistic regression model that included all cases of renal involvement were consistent with those from the Cox model.

CONCLUSIONS

Fcgamma receptor genotype is a risk factor for progression of renal disease to ESRD. Since the frequency distribution of FCGR3A alleles does not vary significantly among the ethnic groups studied, the additional factors underlying the ethnic disparities in renal disease progression remain to be elucidated.

Autoantibody Determination in the Diagnosis of Systemic Lupus Erythematosus

Systemic lupus erythematosus (SLE) is an autoimmune disease that usually develops in young women aged 18-50 years and is characterized by the presence of autoantibodies. Diagnosis is difficult as SLE is a great imitator of other diseases. When SLE is suspected clinically in a patient (involvement of two or more organ systems), an initial laboratory evaluation would be antinuclear antibody (ANA) testing. If ANA is negative, SLE is unlikely and results positive at less than 1:40 strongly argue against SLE. Other explanations for organ system involvement should be pursued. Results positive at greater than 1:40 may merit further evaluation for SLE and at times referral to a rheumatologist for a full SLE evaluation. While the American College of Rheumatology classification criteria for SLE are primarily a tool for research, they may be useful clinically, in that those patients fulfilling four or more criteria are highly likely to have SLE.

B cells move to centre stage: novel opportunities for autoimmune disease treatment

The B-cell arm of the immune system has long been appreciated for its crucial role in pathogen resistance, but in the study of many autoimmune diseases, T cells have dominated the limelight for decades. However, the development of the B-cell-depleting antibody rituximab as a lymphoma therapy has provided a tool to probe the contribution made by B cells in several immune disorders. Recently, the success of B-cell depletion with rituximab in the treatment of rheumatoid arthritis has stimulated investigation of its effects in several other immune disorders, and considerable interest in the potential of drugs that can modulate B-cell function for the treatment of such diseases in general. This article discusses the role of B cells in a range of autoimmune disorders, including rheumatoid arthritis and systemic lupus erythematosus, and analyses approaches to therapeutic B-cell manipulation.

Insulin resistance, chronic inflammatory state and the link with systemic lupus erythematosus-related coronary disease

The association of SLE with atherosclerosis suggests a common pathogenic mechanism. SLE and atherosclerosis are immune complex-mediated diseases. The integration of metabolism and immunity, which under normal conditions is beneficial for the maintenance of good health, can become deteriorative under conditions of metabolic challenge, as exemplified by the immunosuppression characteristic of malnourished or starving individuals. It is now apparent that obesity is associated with a state of chronic inflammation, particularly in white adipose tissue. However, in the absence of obesity, infusion of animals with inflammatory cytokines or lipids can cause insulin resistance. It is possible that the stresses of obesity are similar enough to the stresses of an infection and the body reacts to obesity as it would to an infection. Atherosclerosis can be considered to have a significant chronic inflammatory component. Inflammation also contributes to the typical dyslipidemia associated with SLE that is characterized by elevations of VLDL, LDL and triglycerides as well as reduced HDL. The link between insulin resistance and SLE can be explained by the chronic inflammatory state, and the consequent dyslipoproteinemia.

Innate sensing of self and non-self RNAs by Toll-like receptors

Toll-like receptors (TLRs) have an important role in innate immunity in mammals by recognizing conserved microbial components that are known as pathogen-associated molecular patterns (PAMPs). Although the majority of these receptors sense pathogen components on the cell surface, a subset of them (TLR3, TLR7, TLR8 and TLR9) senses viral and bacterial nucleic acids in endosomal compartments. Of considerable interest is the recent finding that TLR7 and TLR8 can also recognize small interfering RNA (siRNA), which is the main effector in RNA interference. This immune activation by siRNAs can be abrogated by the 2'-ribose modification of uridines. Here, we discuss the recent developments that have expanded the understanding of self-non-self discrimination of RNAs by the innate immune system, and consider future directions for therapeutic applications of these findings.