High serum IFN-alpha activity is a heritable risk factor for systemic lupus erythematosus

Identification of interferon-inducible genes as diagnostic biomarker for systemic lupus erythematosus

The identification of biomarkers helps to perform early diagnosis, thus benefits the outcome of patients with systemic lupus erythematosus (SLE), in which delayed treatment has been proposed as an independent adverse prognostic factor. In this study, we assessed the values of expression levels of five type I interferon (IFN)-inducible genes (LY6E, OAS1, OASL, MX1, and ISG15) and total IFN score for the diagnosis of SLE. Quantitative real-time PCR was applied to determine gene expressions at transcription level in peripheral blood from 69 SLE patients, 42 patients with other connective tissue diseases, and 26 normal controls. Expressions of five genes and IFN score, calculated according to the expressions of IFN-inducible genes, were all significantly increased in SLE patients compared to those in normal subjects and disease controls. IFN score was not related to age, gender, and the dose of steroids, but weakly correlated with SLE disease activity index. None of the gene expression was associated with concomitant infection status or elevated antibodies against Epstein-Barr (EB) virus in SLE. Both modified IFN score (calculated by the expression of three major IFN-inducible genes) and LY6E level showed good diagnostic accuracy in discriminating between SLE patients and disease controls as well as normal subjects (area under the receiver operating characteristic curve was 0.812 and 0.815, respectively), with 70-80 % specificity and 70-80 % sensitivity at the cutoff of 2.37 and 3.23. In conclusion, high IFN-inducible gene expression is constitutional for SLE patients. The modified IFN score or the LY6E level alone may serve as good biomarkers for SLE diagnosis.

Production and characterization of thirteen human type-I interferon-α subtypes

Thirteen human interferon-α (IFNα) subtypes were expressed in Escherichiacoli and purified using an N-terminal affinity tag from the prodomain of subtilisin. IFNα subtypes were expressed in soluble form and purified from cell lysates or refolded and purified from inclusion bodies. Proteins produced by either protocol exhibited biological activities equal to or greater than commercially prepared IFNα preparations. The IFNαs were used to produce an anti-IFNα16 antibody (MAb-1B12) that specifically neutralized the biological activity of IFNα16, but not the 12 other IFNαs. Using MAb-1B12, and a previously generated IFNAR1/IFNAR2-FChk heterodimer, an assay was developed to determine total type I IFN biological activity and IFNα16-derived biological activity in an unknown sample.

Type I interferon in the pathogenesis of lupus

Investigations of patients with systemic lupus erythematosus have applied insights from studies of the innate immune response to define IFN-I, with IFN-α as the dominant mediator, as central to the pathogenesis of this prototype systemic autoimmune disease. Genetic association data identify regulators of nucleic acid degradation and components of TLR-independent, endosomal TLR-dependent, and IFN-I-signaling pathways as contributors to lupus disease susceptibility. Together with a gene expression signature characterized by IFN-I-induced gene transcripts in lupus blood and tissue, those data support the conclusion that many of the immunologic and pathologic features of this disease are a consequence of a persistent self-directed immune reaction driven by IFN-I and mimicking a sustained antivirus response. This expanding knowledge of the role of IFN-I and the innate immune response suggests candidate therapeutic targets that are being tested in lupus patients.

Serum free light chains, interferon-alpha, and interleukins in systemic lupus erythematosus

OBJECTIVE

Interleukin-6 (IL-6), interleukin-10 (IL-10), interferon-alpha (IFN-α), and free light chains (FLCs: lambda, kappa) have all been noted to be of importance in systemic lupus erythematosus (SLE). Herein, we quantified and explored the relationship between these inflammatory mediators and disease activity in SLE; and stratified by their current anti-dsDNA antibody status.

METHODS

Seventy-seven SLE patients underwent assessment of disease activity using the SLE disease activity index (SLEDAI). Serum FLC (lambda, kappa, and total), IL-6, IL-10, and IFN-α were quantified. Demographics of disease characteristics were determined by chart reviews. Statistical analyses included Mann-Whitney test, chi square, and linear regression analyses.

RESULTS

Mean (SD) age of the patients was 44.9 ± 12.7 years; SLEDAI (mean ± SD) was 3.4 ± 4.0. Serum lambda FLC levels had a moderate correlation (r = 0.46 with physician global assessment, 0.44 with SLEDAI) and the strongest correlation with disease activity as compared with other inflammatory mediators including current dsDNA antibody status. After adjusting for prednisone use, the correlation of lambda FLC with PGA (r = 0.48) and SLEDAI (r = 0.52) was better than of current dsDNA antibody status with PGA (r = 0.33) and adjusted SLEDAI (r = 0.24), respectively. IL-10 and IFN-α activity did not correlate with disease activity. Serum FLC and IL-6 levels could differentiate between active and inactive SLE patients. Serum lambda FLC and IL-6 levels differed significantly among patients with and without current dsDNA antibodies. Serum lambda FLC levels accounted for 31% of variance in SLEDAI scores.

CONCLUSION

Serum FLC and IL-6 are potentially useful biomarkers of disease activity in SLE. Further studies, with larger study sample and longitudinal design, are indicated.

Simultaneous changes in serum HMGB1 and IFN-α levels and in LAIR-1 expression on plasmatoid dendritic cells of patients with juvenile SLE. New therapeutic options?

We investigated the simultaneous changes in serum levels of HMGB1 and IFN-α as well as in LAIR-1 expression on plasmatoid dendritic cells (pDCs) of juvenile systemic lupus erythematosus (jSLE) patients in order to explore their involvement in the disease pathogenesis and their correlation with disease activity and other characteristics. In total, 62 blood samples were studied from 26 jSLE patients (18 girls), aged 8-16 years. Twenty healthy subjects (16 girls) of comparable age were included as healthy controls (HCs). Concentrations of serum HMGB1 and IFN-α were assessed by ELISA and LAIR-1 expression on pDCs by five-color flow cytometry. The disease activity index was assessed by SLEDAI and ECLAM scores. It was found that mean serum levels both of HMGB1 and IFN-α were significantly increased in jSLE patients compared to HCs and in jSLE patients with active disease with or without active nephritis compared to those with inactive disease. Mean serum levels of HMGB1 were positively correlated with levels of IFN-α and both were positively correlated with the SLEDAI and ECLAM scores. The expression of LAIR -1 on pDCs of jSLE patients was significantly lower than that of HCs. In conclusion, our findings indicate that serum HMGB1 not only represents a potential marker of disease activity but together with the lack of LAIR-1 inhibitory function may contribute to the sustained inflammatory action of IFN-α in jSLE. In this regard, blocking the action of HMGB1 and its receptors or enhancing the expression/inhibitory function of LAIR-1 on pDCs should be included in future immune interventions for controlling jSLE.

Immune checkpoint receptors in regulating immune reactivity in rheumatic disease

Immune checkpoint regulators are critical modulators of the immune system, allowing the initiation of a productive immune response and preventing the onset of autoimmunity. Co-inhibitory and co-stimulatory immune checkpoint receptors are required for full T-cell activation and effector functions such as the production of cytokines. In autoimmune rheumatic diseases, impaired tolerance leads to the development of diseases such as rheumatoid arthritis, systemic lupus erythematosus, and Sjogren's syndrome. Targeting the pathways of the inhibitory immune checkpoint molecules CD152 (cytotoxic T lymphocyte antigen-4) and CD279 (programmed death-1) in cancer shows robust anti-tumor responses and tumor regression. This observation suggests that, in autoimmune diseases, the converse strategy of engaging these molecules may alleviate inflammation owing to the success of abatacept (CD152-Ig) in rheumatoid arthritis patients. We review the preclinical and clinical developments in targeting immune checkpoint regulators in rheumatic disease.

Genetics of the type I interferon pathway in systemic lupus erythematosus

Genetic studies of systemic lupus erythematosus (SLE) have been successful, identifying numerous risk factors for human disease. While the list is not yet complete, it is clear that important immune system pathways are represented, one of which being type I interferon (IFN). Circulating type I IFN levels are high in SLE patients and this IFN pathway activation is heritable in families with SLE. We summarize our current understanding of the genetics of the type I IFN pathway in SLE, with an emphasis on studies that demonstrate an impact of the SLE-risk alleles upon type I IFN pathway activation in SLE patients. These studies illustrate that variations in type I IFN pathway genes represent a common genetic feature of SLE. By understanding the genetic regulation of type I IFN, we may be able to intervene in a more personalized fashion, based upon the molecular dysregulation present in a given individual.

Nucleic Acid sensors and type I interferon production in systemic lupus erythematosus

The characteristic serologic feature of systemic lupus erythematosus (SLE) is autoantibodies against one’s own nucleic acid or nucleic acid-binding proteins – DNA and RNA-binding nuclear proteins. Circulating autoantibodies can deposit in the tissue, causing inflammation and production of cytokines such as type 1 interferon (IFN). Investigations in human patients and animal models have implicated environmental as well as genetic factors in the biology of the SLE autoimmune response. Viral/Bacterial nucleic acid is a potent stimulant of innate immunity by both toll-like receptor (TLR) and non-TLR signaling cascades. Additionally, foreign DNA may act as an immunogen to drive an antigen-specific antibody response. Self nucleic acid is normally restricted to the nucleus or the mitochondria, away from the DNA/RNA sensors, and mechanisms exist to differentiate between foreign and self nucleic acid. In normal immunity, a diverse range of DNA and RNA sensors in different cell types form a dynamic and integrated molecular network to prevent viral infection. In SLE, pathologic activation of these sensors occurs via immune complexes consisting of autoantibodies bound to DNA or to nucleic acid-protein complexes. In this review, we will discuss recent studies outlining how mismanaged nucleic acid sensing networks promote autoimmunity and result in the over-production of type I IFN. This information is critical for improving therapeutic strategies for SLE disease.

Activation of the Interferon Pathway is Dependent Upon Autoantibodies in African-American SLE Patients, but Not in European-American SLE Patients

Background: In systemic lupus erythematosus (SLE), antibodies directed at RNA-binding proteins (anti-RBP) are associated with high serum type I interferon (IFN), which plays an important role in SLE pathogenesis. African-Americans (AA) are more likely to develop SLE, and SLE is also more severe in this population. We hypothesized that peripheral blood gene expression patterns would differ between AA and European-American (EA) SLE patients, and between those with anti-RBP antibodies and those who lack these antibodies.

Methods: Whole blood RNA from 33 female SLE patients and 16 matched female controls from AA and EA ancestral backgrounds was analyzed on Affymetrix Gene 1.0 ST gene expression arrays. Ingenuity Pathway Analysis was used to compare the top differentially expressed canonical pathways amongst the sample groups. An independent cohort of 116 SLE patients was used to replicate findings using quantitative real-time PCR (qPCR).

Results: Both AA and EA patients with positive anti-RBP antibodies showed over-expression of similar IFN-related canonical pathways, such as IFN Signaling (P = 1.3 × 10⁻⁷ and 6.3 × 10⁻¹¹ in AA vs. EA respectively), Antigen Presenting Pathway (P = 1.8 × 10⁻⁵ and 2.5 × 10⁻⁶), and a number of pattern recognition receptor pathways. In anti-RBP negative (RBP−) patients, EA subjects demonstrated similar IFN-related pathway activation, whereas no IFN-related pathways were detected in RBP−AA patients. qPCR validation confirmed similar results.

Conclusion: Our data show that IFN-induced gene expression is completely dependent on the presence of autoantibodies in AA SLE patients but not in EA patients. This molecular heterogeneity suggests differences in IFN-pathway activation between ancestral backgrounds in SLE. This heterogeneity may be clinically important, as therapeutics targeting this pathway are being developed.

Familial aggregation of high tumor necrosis factor alpha levels in systemic lupus erythematosus

Systemic lupus erythematosus (SLE) patients frequently have high circulating tumor necrosis factor alpha (TNF-α) levels. We explored circulating TNF-α levels in SLE families to determine whether high levels of TNF-α were clustered in a heritable pattern. We measured TNF-α in 242 SLE patients, 361 unaffected family members, 23 unaffected spouses of SLE patients, and 62 unrelated healthy controls. Familial correlations and relative recurrence risk rates for the high TNF-α trait were assessed. SLE-affected individuals had the highest TNF-α levels, and TNF-α was significantly higher in unaffected first degree relatives than healthy unrelated subjects (P = 0.0025). No Mendelian patterns were observed, but 28.4% of unaffected first degree relatives of SLE patients had high TNF-α levels, resulting in a first degree relative recurrence risk of 4.48 (P = 2.9 × 10⁻⁵). Interestingly, the median TNF-α value in spouses was similar to that of the first degree relatives. Concordance of the TNF-α trait (high versus low) in SLE patients and their spouses was strikingly high at 78.2%. These data support a role for TNF-α in SLE pathogenesis, and TNF-α levels may relate with heritable factors. The high degree of concordance in SLE patients and their spouses suggests that environmental factors may also play a role in the observed familial aggregation.

Mediators of inflammation and their effect on resident renal cells: implications in lupus nephritis

Lupus nephritis affects up to 70% of patients with systemic lupus erythematosus and is a major cause of morbidity and mortality. It is characterized by a breakdown of immune tolerance, production of autoantibodies, and deposition of immune complexes within the kidney parenchyma, resulting in local inflammation and subsequent organ damage. To date, numerous mediators of inflammation have been implicated in the development and progression of lupus nephritis, and these include cytokines, chemokines, and glycosaminoglycans. Of these, type I interferons (IFNs) can increase both gene and protein expression of cytokines and chemokines associated with lupus susceptibility, and interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α) and hyaluronan have been shown to elicit both pro- and anti-inflammatory effects on infiltrating and resident renal cells depending on the status of their microenvironment. Expression of IL-6, TNF-α, type I IFNs, and hyaluronan are increased in the kidneys of patients and mice with active lupus nephritis and have been shown to contribute to disease pathogenesis. There is also evidence that despite clinical remission, ongoing inflammatory processes may occur within the glomerular and tubulointerstitial compartments of the kidney, which further promote kidney injury. In this review, we provide an overview of the synthesis and putative roles of IL-6, TNF-α, IFN-α, and hyaluronan in the pathogenesis of lupus nephritis focusing on their effects on human mesangial cells and proximal renal tubular epithelial cells.

Aberrant Type I Interferon Regulation in Autoimmunity: Opposite Directions in MS and SLE, Shaped by Evolution and Body Ecology

Studying the action of mechanisms of type I interferon (IFN) provides the insight to elucidate the cause and therapy for autoimmune diseases. There are high IFN responses in some diseases such as connective tissue diseases, but low responses in multiple sclerosis. Distinct IFN features lead us to understand pathology of a spectrum of autoimmune diseases and help us to search genetic changes, gene expression, and biomarkers for diagnosis, disease progression, and treatment response.

The role of cytokines in the pathogenesis of systemic lupus erythematosus - from bench to bedside

The pathogenesis of systemic lupus erythematosus (SLE) entails a complex interaction between the different arms of the immune system. While autoantibodies production and immune complex deposition are cornered as hallmark features of SLE, there is growing evidence to propose the pathogenic role of cytokines in this disease. Examples of these cytokines include BLys, interleukin-6, interleukin-17, interleukin-18, type I interferons and tumour necrosis factor alpha. These cytokines all assume pivotal functions to orchestrate the differentiation, maturation and activation of various cell types, which would mediate local inflammatory process and tissue injury. The knowledge on these cytokines not only fosters our understanding of the disease, but also provides insights in devising biomarkers and targeted therapies. In this review, we focus on cytokines which have substantial pathogenic significance and also highlight the possible clinical applications of these cytokines.

Interferon-α induction and detection of anti-ro, anti-la, anti-sm, and anti-rnp autoantibodies by autoantigen microarray analysis in juvenile dermatomyositis

OBJECTIVE

To evaluate serum interferon-α (IFNα) activity in the context of autoantibody profiles in patients with juvenile dermatomyositis (JDM).

METHODS

Sera from 36 patients with JDM were analyzed. Autoantibody profiles were determined by probing microarrays, which were fabricated with ∼80 distinct autoantigens, with serum and a Cy3-conjugated secondary antibody. Arrays were scanned and analyzed to determine antigen reactivity. Serum IFNα activity was measured using a functional reporter cell assay. Sera were assayed alone or in combination with cellular material released from necrotic U937 cells to stimulate peripheral blood mononuclear cells from healthy donors in vitro, and IFNα production in culture was measured by a dissociation-enhanced lanthanide fluoroimmunoassay (DELFIA).

RESULTS

Reactivity against at least 1 of 41 autoantigens on the microarray, including Ro 52, Ro 60, La, Sm, and RNP, was observed in 75% of the serum samples from patients with JDM. IFNα activity was detected in 7 samples by reporter cell assay. The reporter cell assay showed a significant association of reactivity against Ro, La, Sm, and proliferating cell nuclear antigen with serum IFNα activity (P = 0.005). Significance Analysis of Microarrays (SAM) identified increased reactivity against Sm, RNP, Ro 52, U1-C, and Mi-2 in these sera. Sixteen samples induced IFNα production as measured by DELFIA, and there was a significant association of reactivity against Ro, La, Sm, and RNP with the induction of IFNα by serum and necrotic cell material (P = 0.034). SAM identified increased reactivity against Ro 60 in these sera.

CONCLUSION

These data support the hypothesis that nucleic acid-associated autoantibodies, including the Ro/La and Sm/RNP complexes, may stimulate the production of active IFNα in children with JDM.

Genetic variation near IRF8 is associated with serologic and cytokine profiles in systemic lupus erythematosus and multiple sclerosis

Alleles of IRF8 are associated with susceptibility to both systemic lupus erythematosus (SLE) and multiple sclerosis (MS). While high type I interferon (IFN) is thought to be causal in SLE, type I IFN is used as a therapy in MS. We investigated whether IRF8 alleles were associated with type I IFN levels or serologic profiles in SLE and MS. Alleles which have been previously associated with SLE or MS were genotyped in SLE and MS patients. The MS-associated rs17445836G allele was associated with anti-dsDNA autoantibodies in SLE patients (meta-analysis OR=1.92). The same allele was associated with decreased serum IFN activity in SLE patients with anti-dsDNA antibodies, and with decreased type I IFN-induced gene expression in PBMC from anti-dsDNA negative SLE patients. In secondary progressive MS patients, rs17445836G was associated with decreased serum type I IFN. Rs17445836G was associated with increased IRF8 expression in SLE patient B cells. In summary, IRF8 rs17445836G is associated with human autoimmune disease characterized by low type I IFN levels, and this may have pharmacogenetic relevance as type I IFN is modulated in SLE and MS. The association with autoantibodies and increased IRF8 expression in B cells supports a role for rs17445836G in humoral tolerance.

Increased serum type I interferon activity in organ-specific autoimmune disorders: clinical, imaging, and serological associations

BACKGROUND

Activation of the type I interferon (IFN) pathway has been implicated in the pathogenesis of systemic autoimmune disorders but its role in the pathogenesis of organ-specific autoimmunity is limited. We tested the hypothesis that endogenous expression of type I IFN functional activity contributes to the pathogenesis of autoimmune thyroid disease (ATD) and type I diabetes (T1DM).

METHODS

We studied 39 patients with ATD and 39 age and sex matched controls along with 88 T1DM patients and 46 healthy matched controls respectively. Available clinical and serological parameters were recorded by chart review, and thyroid ultrasound was performed in 17 ATD patients. Type I IFN serum activity was determined in all subjects using a reporter cell assay. The rs1990760 SNP of the interferon-induced helicase 1 gene was genotyped in ATD patients.

RESULTS

Serum type I IFN activity was increased in patients with ATD and T1DM compared to controls (p-values: 0.002 and 0.04, respectively). ATD patients with high type I IFN serum activity had increased prevalence of antibodies against thyroglobulin (anti-Tg) and cardiopulmonary manifestations compared to those with low IFN activity. Additionally, the presence of micronodules on thyroid ultrasound was associated with higher type I IFN levels. In patients with T1DM, high IFN levels were associated with increased apolipoprotein-B levels.

CONCLUSION

Serum type I IFN activity is increased in ATD and T1DM and is associated with specific clinical, serological, and imaging features. These findings may implicate type I IFN pathway in the pathogenesis of specific features of organ-specific autoimmunity.

Enhanced rho-associated protein kinase activation in patients with systemic lupus erythematosus

OBJECTIVE

Rho-associated protein kinases (ROCKs) have been implicated in the pathogenesis of cardiovascular and renal disorders. We recently showed that ROCKs could regulate the differentiation of murine Th17 cells and the production of interleukin-17 (IL-17) and IL-21, two cytokines associated with systemic lupus erythematosus (SLE). The goal of this study was to assess ROCK activation in human Th17 cells and to evaluate ROCK activity in SLE patients.

METHODS

An enzyme-linked immunosorbent assay (ELISA)-based ROCK activity assay was used to evaluate ROCK activity in human cord blood CD4+ T cells differentiated under Th0 or Th17 conditions. We then performed a cross-sectional analysis of 28 SLE patients and 25 healthy matched controls. ROCK activity in peripheral blood mononuclear cell (PBMC) lysates was determined by ELISA. Cytokine and chemokine profiles were analyzed by ELISA.

RESULTS

Human cord blood CD4+ T cells differentiated under Th17 conditions expressed higher levels of ROCK activity than did CD4+ T cells stimulated under Th0 conditions. Production of IL-17 and IL-21 was inhibited by the addition of a ROCK inhibitor. SLE PBMCs expressed significantly higher levels of ROCK activity than did healthy control PBMCs (1.25 versus 0.56; P = 0.0015). Sixteen SLE patients (57%) expressed high levels of ROCK (optical density at 450 nm >1). Disease duration, lymphocyte count, and azathioprine use were shown to be significant independent predictors of ROCK activity in multivariable analyses.

CONCLUSION

Consistent with previous results in the murine system, increased ROCK activation was associated with Th17 cell differentiation. Moreover, enhanced ROCK activity was observed in a subgroup of SLE patients. These data support the concept that the ROCK pathway could represent an important therapeutic target for SLE.

Genome-wide DNA methylation analysis of systemic lupus erythematosus reveals persistent hypomethylation of interferon genes and compositional changes to CD4+ T-cell populations

Systemic lupus erythematosus (SLE) is an autoimmune disease with known genetic, epigenetic, and environmental risk factors. To assess the role of DNA methylation in SLE, we collected CD4+ T-cells, CD19+ B-cells, and CD14+ monocytes from 49 SLE patients and 58 controls, and performed genome-wide DNA methylation analysis with Illumina Methylation450 microarrays. We identified 166 CpGs in B-cells, 97 CpGs in monocytes, and 1,033 CpGs in T-cells with highly significant changes in DNA methylation levels (p<1×10⁻⁸) among SLE patients. Common to all three cell-types were widespread and severe hypomethylation events near genes involved in interferon signaling (type I). These interferon-related changes were apparent in patients collected during active and quiescent stages of the disease, suggesting that epigenetically-mediated hypersensitivity to interferon persists beyond acute stages of the disease and is independent of circulating interferon levels. This interferon hypersensitivity was apparent in memory, naïve and regulatory T-cells, suggesting that this epigenetic state in lupus patients is established in progenitor cell populations. We also identified a widespread, but lower amplitude shift in methylation in CD4+ T-cells (>16,000 CpGs at FDR<1%) near genes involved in cell division and MAPK signaling. These cell type-specific effects are consistent with disease-specific changes in the composition of the CD4+ population and suggest that shifts in the proportion of CD4+ subtypes can be monitored at CpGs with subtype-specific DNA methylation patterns.

We have analyzed DNA methylation, an epigenetic modification that influences gene expression, in lupus patients and control subjects. Our analysis was run in three different immune cell types, T-cells, B-cells, and monocytes, to discern common epigenetic effects in lupus from cell type-specific effects. We have identified a lupus-related reduction in methylation around genes that respond to interferon, a cytokine that induces inflammation in response to pathogens. This hypomethylation suggests that lupus patients are hypersensitive to interferon, as DNA methylation is typically an inhibitor of gene expression. We also find that this hypersensitivity is preserved in lupus patients beyond active stages of the disease, and this may help explain the chronic, recurrent nature of the disease. In addition, we have identified DNA methylation changes in T-cells that suggest an alteration in the proportions of these cells in lupus patients, which may help explain the disease process.

Kinetic analysis of cytokine-mediated receptor assembly using engineered FC heterodimers

A method for analyzing ligand-receptor binding kinetics is described, which is based on an engineered FC domain (FChk) that forms a covalent heterodimer. To validate the system, the type I IFN receptors (IFNAR1 and IFNAR2) were expressed as IFNAR1-FChk, IFNAR2-FCkh, and IFNAR1/IFNAR2-FChk fusion proteins. Surface plasmon resonance (SPR) analysis of binary IFNα2a/IFNAR interactions confirmed prior affinity measurements, while the affinity of the IFNα2a/IFNAR1/IFNAR2-FChk interaction reproduced the affinity of IFNα2a binding to living cells. In cellular assays, IFNAR1/IFNAR2-FChk potently neutralized IFNα2a bioactivity with an inhibitory concentration equivalent to the KD measured by SPR. These studies suggest that FChk provides a simple reagent to evaluate the binding kinetics of multiple ligand-receptor signaling systems that control cell growth, development, and immunity.

Cancer immunotherapy strategies based on overcoming barriers within the tumor microenvironment

For tumor antigen-specific T cells to effectively control the growth of cancer cells in vivo, they must gain access to, and function within, the tumor microenvironment. While tumor antigen-based vaccines and T cell adoptive transfer strategies can result in clinical benefit in a subset of patients, most of the patients do not respond clinically. Even for tumor-infiltrating lymphocyte (TIL)-based adoptive transfer for patients with metastatic melanoma, which can provide tumor shrinkage in around 50% of treated individuals, many patients are not eligible, in part because there are not sufficient TIL present in the resected tumor. Thus, the denominator is in fact larger, and it has been suggested that absence of TIL may be a marker for poor efficacy of immunotherapies in general. While qualitative and/or quantitative features of the T cells are important considerations for efficacy, a major component of primary resistance likely can be attributed to the tumor microenvironment. Data are accumulating suggesting that two major categories of immune resistance within the tumor microenvironment may exist: failure of T cell trafficking due to low levels of inflammation and lack of chemokines for migration, and dominant suppression through immune inhibitory mechanisms. New therapeutic interventions are being guided by these observations, and preliminary clinical success is validating this working model.

Distinct autoantibody profiles in systemic lupus erythematosus patients are selectively associated with TLR7 and TLR9 upregulation

PURPOSE

Systemic lupus erythematosus (SLE) patients have a wide array of autoantibodies against nuclear antigens. The two predominant classes of these autoantibodies are directed either against dsDNA or RNA-associated antigens (extractable nuclear antigens; ENA). Nucleic-acid sensing Toll-like receptors (TLRs) that recognize dsDNA and RNA, have been well implicated in some murine models of SLE. We took up this study to identify if unique TLR expression patterns are associated with distinct autoantibody profiles in SLE.

METHODS

We segregated the patients into three subsets distinguished on the basis of autoantibody response either against dsDNA or ENA or both. We determined the mRNA expression of TLR3, 7, 8, and 9 by real-time reverse-transcription PCR in peripheral blood leucocytes (PBLs) of the SLE patients of all three subsets. TLR7 and 9 protein expression was determined by western blotting in PBLs and by flow cytometry on B-cells and monocytes. The serum interferon-alpha (IFN-α) and anti-dsDNA/-ENA autoantibodies were detected using enzyme-linked immunosorbant assay.

RESULTS

We report differential and unique TLR expression patterns associated with different autoantibody profiles. The presence of anti-ENA and anti-dsDNA autoantibodies in SLE patients was associated with elevated levels of TLR7 and TLR9 respectively. The TLR9 mRNA expression was further augmented in SLE patients with Glomerulonephritis. Interestingly, anti-dsDNA(+) ENA(+) patients displayed higher serum IFN-α and interferon regulatory factor 7 mRNA expression than patients with either anti-dsDNA or anti-ENA autoantibodies alone.

CONCLUSION

Characteristic TLRs expression profile associated with distinct autoantibody repertoire is suggestive of differential immuno-regulatory pathways operative in different subsets of SLE patients.

Functional genetic polymorphisms in ILT3 are associated with decreased surface expression on dendritic cells and increased serum cytokines in lupus patients

OBJECTIVE

Hyperactivity of the type I interferon (IFN) pathway is involved in the pathogenesis of systemic lupus erythematosus (SLE). Immunoglobulin like transcript (ILT3) is an immunohibitory transmembrane molecule which is induced by type I IFNs. ILT3 is expressed by plasmacytoid dendritic cells (PDCs), monocytoid dendritic cells (MDCs), and monocytes/macrophages. Given the pathogenic role of IFN in SLE, we hypothesised that the IFN-induced immunosuppressive ILT3 receptor may be dysfunctional in human SLE.

METHODS

132 European-derived and 79 Hispanic-American SLE patients were genotyped for two coding-change single nucleotide polymorphisms (SNPs) predicted to interfere with protein folding in ILT3 (rs11540761 and rs1048801). 116 control DNA samples and sera from healthy controls were also studied. We detected associations between ILT3 genotype and serum cytokine profiles. ILT3 expression levels on PDCs and MDCs from 18 patients and 10 controls were studied by flow cytometry.

RESULTS

The rs11540761 SNP in the extracellular region was associated with decreased cell surface expression of ILT3 on circulating MDCs and to a lesser extent PDCs in SLE patients. The cytoplasmically located rs1048801 SNP was not associated with a change in dendritic cells expression of ILT3. Both SNPs were significantly and independently associated with increased levels of serum type I IFN activity in SLE patients. The rs1048801 SNP was also associated with increased serum levels of TNF-α.

CONCLUSIONS

Loss-of-function polymorphisms in ILT3 are associated with increased inflammatory cytokine levels in SLE, supporting a biological role for ILT3 in SLE.

Parental history of lupus and rheumatoid arthritis and risk in offspring in a nationwide cohort study: does sex matter?

OBJECTIVES

To examine the familial risk of systemic lupus erythematosus (SLE) and rheumatoid arthritis (RA), including juvenile rheumatoid/idiopathic arthritis (JRA), in a population-based setting; and to determine whether patterns of transmission differ according to the sex of the parent or offspring, in order to provide insight into the potential impact of X-chromosomal factors on sex disparities in these autoimmune diseases.

METHODS

A population-based cohort of parent-offspring triads from Denmark (1977-2010) was established. SLE and RA incidence rates among offspring were calculated, and Cox regression was performed to assess the sex-specific risk of disease in offspring according to maternal or paternal disease history.

RESULTS

Among 3 513 817 parent-offspring triads, there were 1258 SLE cases among offspring (1095 female, 163 male) and 9118 cases of RA/JRA (6086 female, 3032 male). Among female offspring, SLE risk was nearly the same according to maternal (HR 14.1) or paternal (HR 14.5) history (p=NS); likewise among male offspring, risk according to maternal (HR 5.5) and paternal (no cases) history were similar (p=NS). For RA, all risk estimates were similar, regardless of the sex of the offspring or parent (HR 2.6-2.9; p=NS).

CONCLUSIONS

The authors quantified the familial risk of SLE and RA in a nationwide cohort study. For both diseases, transmission was comparable among both female and male offspring of maternal and paternal cases. These data provide evidence at the population level that X-chromosomal factors do not play a major role in sex disparities associated with the risk of SLE and RA.

Inhibition of interferon-beta responses in multiple sclerosis immune cells associated with high-dose statins

OBJECTIVE

To determine whether statins affect type 1 interferon responses in relapsing-remitting multiple sclerosis (RRMS).

DESIGN

Study effects of atorvastatin on type 1 interferon responses in Jurkat cells, mononuclear cells (MNCs) from therapy-naive patients with RRMS in vitro, and MNCs from interferon-treated RRMS patients in vivo in 4 conditions: no drug, statin only, interferon-beta only, and statin added on to interferon-beta therapy.

PATIENTS

The study examined clinically stable patients with RRMS: 21 therapy-naive patients and 14 patients receiving interferon-beta with a statin.

INTERVENTIONS

Statin effects on in vitro and in vivo interferon-beta-induced STAT1 transcription factor activation, expression of interferon-stimulated proteins in MNCs, and serum type 1 interferon activity.

RESULTS

In vitro, atorvastatin dose dependently inhibited expression of interferon-stimulated P-Y-STAT1 by 44% (P < .001), interferon regulatory factor 1 protein by 30% (P=.006), and myxovirus resistance 1 protein by 32% (P=.004) compared with no-statin control in MNCs from therapy-naive RRMS patients. In vivo, 9 of 10 patients who received high-dose statins (80 mg) had a significant reduction in interferon-beta therapy-induced serum interferon-α/β activity, whereas only 2 of 4 patients who received medium- dose statins (40 mg) had reductions. High-dose add-on statin therapy significantly blocked interferon-beta function, with less P-Y-STAT1 transcription factor activation, and reduced myxovirus resistance 1 protein and viperin protein production. Medium doses of statins did not change STAT1 activation.

CONCLUSIONS

High-dose add-on statin therapy significantly reduces interferon-beta function and type 1 interferon responses in RRMS patients. These data provide a putative mechanism for how statins could counteract the beneficial effects of interferon-beta and worsen disease.

Anti-interferon alpha treatment in SLE

Several studies in the last decade have highlighted the role of the type I interferon (IFN-I) pathway, and particularly interferon alpha (IFNα) in SLE pathogenesis. As a result, a multitude of potential treatments targeting IFNα have emerged in the last few years, a few of which have already completed phase II clinical trials. Some of the treatment strategies have focused on blocking IFNα or its receptor and others the plasmacytoid dendritic cell (pDC), which is the principal IFNα producing cell. In this review, we will discuss the evidence supporting a pathogenic role of IFNα and pDC in SLE, provide an update on the current status of these therapeutic strategies, and discuss the potential advantages and disadvantages of each therapeutic approach.

Mechanistic biomarkers for clinical decision making in rheumatic diseases

The use of biomarkers is becoming increasingly intrinsic to the practice of medicine and holds great promise for transforming the practice of rheumatology. Biomarkers have the potential to aid clinical diagnosis when symptoms are present or to provide a means of detecting early signs of disease when they are not. Some biomarkers can serve as early surrogates of eventual clinical outcomes or guide therapeutic decision making by enabling identification of individuals likely to respond to a specific therapy. Using biomarkers might reduce the costs of drug development by enabling individuals most likely to respond to be enrolled in clinical trials, thereby minimizing the number of participants required. In this Review, we discuss the current use and the potential of biomarkers in rheumatology and in select fields at the forefront of biomarker research. We emphasize the value of different types of biomarkers, addressing the concept of 'actionable' biomarkers, which can be used to guide clinical decision making, and 'mechanistic' biomarkers, a subtype of actionable biomarker that is embedded in disease pathogenesis and, therefore, represents a potentially superior biomarker. We provide examples of actionable and mechanistic biomarkers currently available, and discuss how development of such biomarkers could revolutionize clinical practice and drug development.

Plasma levels of osteopontin identify patients at risk for organ damage in systemic lupus erythematosus

Introduction

Osteopontin (OPN) has been implicated as a mediator of Th17 regulation via type I interferon (IFN) receptor signaling and in macrophage activity at sites of tissue repair. This study assessed whether increased circulating plasma OPN (cOPN) precedes development of organ damage in pediatric systemic lupus erythematosus (pSLE) and compared it to circulating plasma neutrophil gelatinase-associated lipocalin (cNGAL), a predictor of increased SLE disease activity.

Methods

cOPN and cNGAL were measured in prospectively followed pSLE (n = 42) and adult SLE (aSLE; n = 23) patients and age-matched controls. Time-adjusted cumulative disease activity and disease damage were respectively assessed using adjusted-mean SLE disease activity index (SLEDAI) (AMS) and SLICC/ACR damage index (SDI).

Results

Compared to controls, elevated cOPN and cNGAL were observed in pSLE and aSLE. cNGAL preceded worsening SLEDAI by 3-6 months (P = 0.04), but was not associated with increased 6-month AMS. High baseline cOPN, which was associated with high IFNalpha activity and expression of autoantibodies to nucleic acids, positively correlated with 6-month AMS (r = 0.51 and 0.52, P = 0.001 and 0.01 in pSLE and aSLE, respectively) and was associated with SDI increase at 12 months in pSLE (P = 0.001). Risk factors for change in SDI in pSLE were cOPN (OR 7.5, 95% CI [2.9-20], P = 0.03), but not cNGAL, cumulative prednisone, disease duration, immunosuppression use, gender or ancestry using univariate and multivariate logistic regression. The area under the curve (AUC) when generating the receiver-operating characteristic (ROC) of baseline cOPN sensitivity and specificity for the indication of SLE patients with an increase of SDI over a 12 month period is 0.543 (95% CI 0.347-0.738; positive predictive value 95% and negative predictive value 38%).

Conclusion

High circulating OPN levels preceded increased cumulative disease activity and organ damage in SLE patients, especially in pSLE, and its value as a predictor of poor outcome should be further validated in large longitudinal cohorts.

RNA-Seq for enrichment and analysis of IRF5 transcript expression in SLE

Polymorphisms in the interferon regulatory factor 5 (IRF5) gene have been consistently replicated and shown to confer risk for or protection from the development of systemic lupus erythematosus (SLE). IRF5 expression is significantly upregulated in SLE patients and upregulation associates with IRF5-SLE risk haplotypes. IRF5 alternative splicing has also been shown to be elevated in SLE patients. Given that human IRF5 exists as multiple alternatively spliced transcripts with distinct function(s), it is important to determine whether the IRF5 transcript profile expressed in healthy donor immune cells is different from that expressed in SLE patients. Moreover, it is not currently known whether an IRF5-SLE risk haplotype defines the profile of IRF5 transcripts expressed. Using standard molecular cloning techniques, we identified and isolated 14 new differentially spliced IRF5 transcript variants from purified monocytes of healthy donors and SLE patients to generate an IRF5 variant transcriptome. Next-generation sequencing was then used to perform in-depth and quantitative analysis of full-length IRF5 transcript expression in primary immune cells of SLE patients and healthy donors by next-generation sequencing. Evidence for additional alternatively spliced transcripts was obtained from de novo junction discovery. Data from these studies support the overall complexity of IRF5 alternative splicing in SLE. Results from next-generation sequencing correlated with cloning and gave similar abundance rankings in SLE patients thus supporting the use of this new technology for in-depth single gene transcript profiling. Results from this study provide the first proof that 1) SLE patients express an IRF5 transcript signature that is distinct from healthy donors, 2) an IRF5-SLE risk haplotype defines the top four most abundant IRF5 transcripts expressed in SLE patients, and 3) an IRF5 transcript signature enables clustering of SLE patients with the H2 risk haplotype.

Th1/Th2 cytokine profile in childhood-onset systemic lupus erythematosus

OBJECTIVE

To determine the serum levels of Th1 (IL-12, IFN-γ,TNF-α) and Th2 (IL-5, IL-6 and IL-10) cytokines in childhood-onset SLE, first-degree relatives and healthy controls. To elucidate their association with disease activity, laboratory and treatment features.

METHODS

We included 60 consecutive childhood-onset SLE patients [median age 18 years (range 10-37)], 64 first-degree relatives [median 40 (range 28-52)] and 57 healthy [median age 19 years (range 6-30 years)] controls. Controls were age and sex-matched to SLE patients. SLE patients were assessed for clinical and laboratory SLE manifestations, disease activity (SLEDAI), damage (SDI) and current drug exposures. Mood and anxiety disorders were determined through Becks Depression (BDI) and Anxiety Inventory (BAI). Th1 (IL-12, IFN-γ,TNF-α) and Th2 (IL-5, IL-6 and IL-10) cytokines levels were measured by ELISA and compared by non-parametric tests.

RESULTS

Serum TNF-α (p=0.004), IL-6 (p=0.007) and IL-10 (p=0.03) levels were increased in childhood-onset SLE patients when compared to first-degree relatives and healthy controls. TNF-α levels were significantly increased in patients with active disease (p=0.014) and correlated directly with SLEDAI scores (r=0.39; p=0.002). IL-12 (p=0.042) and TNF-α (p=0.009) levels were significantly increased in patients with nephritis and TNF-α in patients with depression (p=0.001). No association between cytokine levels and SDI scores or medication was observed.

CONCLUSION

Th1 cytokines may play a role in the pathogenesis of neuropsychiatric and renal manifestations in childhood-onset SLE. The correlation with SLEDAI suggests that TNF-α may be a useful biomarker for disease activity in childhood-onset SLE, however longitudinal studies are necessary to determine if increase of this cytokine may predict flares in childhood-onset SLE.

Brief Report: IRF5 systemic lupus erythematosus risk haplotype is associated with asymptomatic serologic autoimmunity and progression to clinical autoimmunity in mothers of children with neonatal lupus

OBJECTIVE

Variation in the interferon regulatory factor 5 (IRF5) gene has been associated with risk of developing systemic lupus erythematosus (SLE), and this association is largely dependent upon anti-Ro autoantibodies. This study was undertaken to determine if the IRF5 genotype is associated with maternal diagnosis or progression of autoimmunity.

METHODS

Genotyping of haplotype-tagging polymorphisms in IRF5 was performed in 93 subjects of European ancestry who were recruited to the Research Registry for Neonatal Lupus. All subjects had high-titer anti-Ro autoantibodies and had a child with neonatal lupus (NL); allele frequencies were compared to those in nonautoimmune controls. The mothers had SLE, Sjögren's syndrome (SS), or undifferentiated autoimmune syndrome (UAS), or were asymptomatic.

RESULTS

The SLE risk haplotype of IRF5 was enriched in all anti-Ro-positive subjects except in those with SS (odds ratio [OR] 2.55, P = 8.8 × 10(-4) ). The SLE risk haplotype was even enriched in asymptomatic individuals with anti-Ro antibodies (OR 2.69, P = 0.019). The same haplotype was more prevalent in subjects who were initially asymptomatic but developed symptomatic SLE during followup (OR 5.83, P = 0.0024). Interestingly, SS was associated with 2 minor IRF5 haplotypes, and these same haplotypes were decreased in frequency in mothers with SLE and those with UAS.

CONCLUSION

The IRF5 SLE risk haplotype was associated with anti-Ro antibody positivity in asymptomatic individuals, as well as with progression to SLE in asymptomatic anti-Ro-positive individuals. SS in mothers of children with NL was associated with different IRF5 haplotypes. These data suggest that IRF5 polymorphisms play a role in serologic autoimmunity in humans and may promote the progression to clinical autoimmunity.

A diverse array of genetic factors contribute to the pathogenesis of systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is a chronic systemic autoimmune disease with variable clinical presentation frequently affecting the skin, joints, haemopoietic system, kidneys, lungs and central nervous system. It can be life threatening when major organs are involved. The full pathological and genetic mechanisms of this complex disease are yet to be elucidated; although roles have been described for environmental triggers such as sunlight, drugs and chemicals, and infectious agents. Cellular processes such as inefficient clearing of apoptotic DNA fragments and generation of autoantibodies have been implicated in disease progression. A diverse array of disease-associated genes and microRNA regulatory molecules that are dysregulated through polymorphism and copy number variation have also been identified; and an effect of ethnicity on susceptibility has been described.

Large-scale analysis of tumor necrosis factor α levels in systemic lupus erythematosus

OBJECTIVE

Systemic lupus erythematosus (SLE) disease manifestations are highly variable among patients, and the prevalence of individual clinical features differs significantly by ancestry. Serum tumor necrosis factor α (TNFα) levels are elevated in some SLE patients and may play a role in disease pathogenesis. The aim of this study was to look for associations between serum TNFα levels, clinical manifestations of SLE, autoantibodies, and serum interferon-α (IFNα) levels in a large multiancestral SLE cohort.

METHODS

We studied serum TNFα levels in 653 SLE patients (214 African Americans, 298 European Americans, and 141 Hispanic Americans). TNFα was measured using an enzyme-linked immunosorbent assay, and IFNα was measured with a functional reporter cell assay. Stratified and multivariate analyses were used to detect associations in each ancestral background separately, with meta-analysis when appropriate.

RESULTS

Serum TNFα levels were significantly higher in SLE patients than in non-autoimmune disease controls (P < 5.0 × 10(-3) for each ancestral background). High serum TNFα levels were positively correlated with high serum IFNα levels when tested in the same sample across all ancestral backgrounds (odds ratio range 1.76-1.86, P = 4.8 × 10(-3) by Fisher's combined probability test). While serum TNFα levels alone did not differ significantly among SLE patients of different ancestral backgrounds, the proportion of patients with concurrently high levels of TNFα and IFNα was highest in African Americans and lowest in European Americans (P = 5.0 × 10(-3) ). Serum TNFα levels were not associated with autoantibodies, clinical criteria for the diagnosis of SLE, or age at the time of sampling.

CONCLUSION

Serum TNFα levels are high in many SLE patients, and we observed a positive correlation between serum TNFα and IFNα levels. These data support a role for TNFα in the pathogenesis of SLE across all ancestral backgrounds and suggest important cytokine subgroups within the disease.

Family history of autoimmune disease in patients with Aicardi-Goutières syndrome

Purpose. The purpose of this study was to explore anecdotal evidence for an increase in the prevalence of autoimmune diseases in family members of patients with Aicardi-Goutières syndrome (AGS). Methods. Pedigrees of patients and controls were analyzed using chi-square and logistic regression to assess differences in reports of autoimmune disease among family members of cases and controls. Data was collected at Children's National Medical Center in Washington, DC, USA and at the International Aicardi-Goutières Syndrome Association Scientific Headquarters, C. Mondino National Institute of Neurology in Pavia, Italy. Results. The number of individuals with reported autoimmune disease is significantly related to having a family member with AGS (χ² = 6.25, P = 0.01); 10% (35/320) of relatives of patients with AGS had a reported autoimmune disease diagnosis compared to 5% (18/344) of relatives of controls. There was a greater percent of maternal relatives of patients with AGS reporting autoimmune disease (14.6%), compared to controls (6.8%), with the association being statistically significant. The association was not significant for paternal relatives. Conclusion. The prevalence of autoimmune disease in relatives of children with AGS is significantly increased compared to controls. More research is needed to better understand this association.

Increased IFNα activity and differential antibody response in patients with a history of Lyme disease and persistent cognitive deficits

Following antibiotic treatment for Lyme disease, some patients report persistent or relapsing symptoms of pain, fatigue, and/or cognitive deficits. Factors other than active infection, including immune abnormalities, have been suggested, but few clues regarding mechanism have emerged. Furthermore, the effect of antibiotic treatment on immune response in affected individuals remains unknown. In this study, a longitudinal analysis of specific immune markers of interest was carried out in patients with a history of Lyme disease and persistent objective memory impairment, prior to and following treatment with either ceftriaxone or placebo. IFNα activity was measured by detection of serum-induced changes in specific target genes, using a functional cell-based assay and quantitative real-time PCR. Level and pattern of antibody reactivity to brain antigens and to Borrelia burgdorferi proteins were analyzed by ELISA and immunoblotting. Sera from the patient cohort induced significantly higher expression of IFIT1 and IFI44 target genes than those from healthy controls, indicating increased IFNα activity. Antibody reactivity to specific brain and borrelial proteins was significantly elevated in affected patients. IFNα activity and antibody profile did not change significantly in response to ceftriaxone. The heightened antibody response implies enhanced immune stimulation, possibly due to prolonged exposure to the organism prior to the initial diagnosis and antibiotic treatment of Lyme disease. The increase in IFNα activity is suggestive of a mechanism contributing to the ongoing neuropsychiatric symptoms.

Interferon regulatory factor 5 in the pathogenesis of systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is an autoimmune disease characterized by multiple genetic risk factors, high levels of interferon alpha (IFN-α), and the production of autoantibodies against components of the cell nucleus. Interferon regulatory factor 5 (IRF5) is a transcription factor which induces the transcription of IFN-α and other cytokines, and genetic variants of IRF5 have been strongly linked to SLE pathogenesis. IRF5 functions downstream of Toll-like receptors and other microbial pattern-recognition receptors, and immune complexes made up of SLE-associated autoantibodies seem to function as a chronic endogenous stimulus to this pathway. In this paper, we discuss the physiologic role of IRF5 in immune defense and the ways in which IRF5 variants may contribute to the pathogenesis of human SLE. Recent data regarding the role of IRF5 in both serologic autoimmunity and the overproduction of IFN-α in human SLE are summarized. These data support a model in which SLE-risk variants of IRF5 participate in a “feed-forward” mechanism, predisposing to SLE-associated autoantibody formation, and subsequently facilitating IFN-α production downstream of Toll-like receptors stimulated by immune complexes composed of these autoantibodies.

GWAS implicates a role for quantitative immune traits and threshold effects in risk for human autoimmune disorders

Genome wide association studies in human autoimmune disorders have provided a long list of alleles with rather modest degrees of risk. A large fraction of these associations are probably owing to either quantitative differences in gene expression or amino acid changes that regulate quantitative aspects of the immune response. While functional studies are still lacking for most of these associations, we present examples of autoimmune disease risk alleles that influence quantitative changes in lymphocyte activation, cytokine signaling and dendritic cell function. The analysis of immune quantitative traits associated with autoimmune loci is clearly going to be an important component of understanding the pathogenesis of autoimmunity. This will require both new and more efficient ways of characterizing the normal immune system, as well as large population resources in which genotype-phenotype correlations can be convincingly demonstrated. Future development of new therapies will depend on understanding the mechanistic underpinnings of immune regulation by these new risk loci.

Innate immune sensing of cancer: clues from an identified role for type I IFNs

A subset of patients with a variety of cancers shows evidence of a natural adaptive immune response against their tumor, as evidenced by spontaneous T-cell infiltration, circulating anti-tumor T cells, or antibody responses. Evidence has indicated that such natural immune responses have positive prognostic import in early stage disease and may be predictive of clinical response to immunotherapeutics in advanced disease. However, these observations raise a new critical fundamental question-what innate immune signals might be generated in the context of non-pathogen-induced cancers that drive productive antigen presentation toward induction of an adaptive immune response? Gene expression profiling in melanoma revealed that tumors having high expression of T-cell markers also show evidence of a type I IFN transcriptional signature. Mechanistic experiments in mice have revealed that a spontaneous CD8(+) T-cell response against transplantable tumors depends on host type I IFN signaling, through a mechanism dependent upon CD8α(+) dendritic cells (DCs). The requirement for type I IFN production by host DCs has suggested a subset of innate immune sensing receptors and signaling pathways that might be involved with initiating this process. Elucidating further these innate immune mechanisms should provide new insights into cancer immunotherapy.

Altered expression of TNFSF4 and TRAF2 mRNAs in peripheral blood mononuclear cells in patients with systemic lupus erythematosus: association with atherosclerotic symptoms and lupus nephritis

OBJECTIVES

This study compares the expression levels of tumor necrosis factor ligand superfamily member 4 (TNFSF4) and TNF-R-associated factor 2 (TRAF2) mRNAs in peripheral blood mononuclear cells (PBMCs) of patients with systemic lupus erythematosus (SLE) against healthy controls. The association of SLE disease activity index (SLEDAI) and clinical features of SLE with altered expression levels of TNFSF4 and TRAF2 mRNAs were also evaluated.

DESIGN

We used real-time reverse transcription polymerase chain reaction to measure TNFSF4 and TRAF2 mRNAs expression levels in peripheral blood mononuclear cells of 57 SLE patients and 57 healthy controls.

RESULTS

The expression level of TNFSF4 mRNA was significantly higher in SLE patients than in the control group. Overexpression of TNFSF4 was correlated with arthritis, atherosclerosis and lupus nephritis. TRAF2 mRNA was underexpressed in PBMCs of SLE patients, and its lower expression was associated with atherosclerosis and lupus nephritis. The altered expression levels of TNFSF4 and TRAF2 mRNAs was significantly correlated with SLEDAI.

CONCLUSION

Our results suggest that changes in the expression levels of TNFSF4 and TRAF2 mRNAs may significantly correlate with the pathogenesis of SLE, the disease activity and different clinical features of lupus, particularly lupus nephritis, atherosclerosis and arthritis.

Gene-expression-guided selection of candidate loci and molecular phenotype analyses enhance genetic discovery in systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is a highly heterogeneous autoimmune disorder characterized by differences in autoantibody profiles, serum cytokines, and clinical manifestations. We have previously conducted a case-case genome-wide association study (GWAS) of SLE patients to detect associations with autoantibody profile and serum interferon alpha (IFN-α). In this study, we used public gene expression data sets to rationally select additional single nucleotide polymorphisms (SNPs) for validation. The top 200 GWAS SNPs were searched in a database which compares genome-wide expression data to genome-wide SNP genotype data in HapMap cell lines. SNPs were chosen for validation if they were associated with differential expression of 15 or more genes at a significance of P < 9 × 10(-5). This resulted in 11 SNPs which were genotyped in 453 SLE patients and 418 matched controls. Three SNPs were associated with SLE-associated autoantibodies, and one of these SNPs was also associated with serum IFN-α (P < 4.5 × 10(-3) for all). One additional SNP was associated exclusively with serum IFN-α. Case-control analysis was insensitive to these molecular subphenotype associations. This study illustrates the use of gene expression data to rationally select candidate loci in autoimmune disease, and the utility of stratification by molecular phenotypes in the discovery of additional genetic associations in SLE.

The plasma level of soluble receptor for advanced glycation end products is decreased in patients with systemic lupus erythematosus

In recent years, the role of high mobility group box-1 (HMGB1) protein and its receptors in autoimmune diseases has received increasing attention. It has been documented that HMGB1 is associated with disease activity in patients with systemic lupus erythematosus (SLE). This study was undertaken to determine the potential role of receptor for advanced glycation end products (RAGE), one receptor for HMGB1, in the pathogenesis of SLE. Plasma levels of soluble RAGE (sRAGE) from 105 patients with clinical diagnosis of SLE and 43 healthy controls were determined by ELISA. Associations between sRAGE levels and clinical, laboratory characteristics were assessed. The data showed that plasma levels of sRAGE in patients with SLE were significantly lower than those in healthy controls (HC) (P = 0.003). Plasma sRAGE in patients receiving short-period treatment showed an immediate decrease compared with the untreated patients (P = 0.023). In contrast, plasma sRAGE in patients receiving long-period treatment were significantly increased compared to those with short-period treatment (P = 0.000) and comparable with those in HC (P = 0.305). The significant decreased levels of sRAGE in patients with SLE suggest the potential association of RAGE signalling and SLE clinical pathology, whereas, long-period antilupus treatment may counteract the decreased sRAGE levels in patients with SLE.

Genetic ancestry, serum interferon-α activity, and autoantibodies in systemic lupus erythematosus

OBJECTIVE

To investigate and refine the relationships among systemic lupus erythematosus (SLE) and related autoantibodies, interferon-α (IFN-α), and various ancestral backgrounds.

METHODS

We investigated quantitatively defined genetic ancestry through principal component analysis in place of self-reported ancestry.

RESULTS

African ancestry was found to be associated with presence of anti-RNP antibody (p = 0.0026), and anti-RNP was correlated with high levels of IFN-α (p = 2.8 × 10(-5)).

CONCLUSION

Our data support a model in which African ancestry increases the likelihood of SLE-associated autoantibody formation, which subsequently results in higher levels of serum IFN-α.

Myeloid dendritic cells from B6.NZM Sle1/Sle2/Sle3 lupus-prone mice express an IFN signature that precedes disease onset

Patients with systemic lupus erythematosus show an overexpression of type I IFN-responsive genes that is referred to as "IFN signature." We found that B6.NZMSle1/Sle2/Sle3 (Sle1,2,3) lupus-prone mice also express an IFN signature compared with non-autoimmune C57BL/6 mice. In vitro, myeloid dendritic cells (mDCs) (GM-CSF bone marrow-derived dendritic cells; BMDCs) from Sle1,2,3 mice constitutively overexpressed IFN-responsive genes such as IFN-β, Oas-3, Mx-1, ISG-15, and CXCL10 and members of the IFN signaling pathway STAT1, STAT2, and IRF7. The IFN signature was similar in Sle1,2,3 BMDCs from young, pre-autoimmune mice and from mice with high titers of autoantibodies, suggesting that the IFN signature in mDCs precedes disease onset and is independent from the autoantibodies. Sle1,2,3 BMDCs hyperresponded to stimulation with IFN-α and the TLR7 and TLR9 agonists R848 and CpGs. We propose that this hyperresponse is induced by the IFN signature and only partially contributes to the signature, as oligonucleotides inhibitory for TLR7 and TLR9 only partially suppressed the constitutive IFN signature, and pre-exposure to IFN-α induced the same hyperresponse in wild-type BMDCs as in Sle1,2,3 BMDCs. In vivo, mDCs and to a lesser extent T and B cells from young prediseased Sle1,2,3 mice also expressed the IFN signature, although they lacked the strength that BMDCs showed in vitro. Sle1,2,3 plasmacytoid DCs expressed the IFN signature in vitro but not in vivo, suggesting that mDCs may be more relevant before disease onset. We propose that Sle1,2,3 mice are useful tools to study the role of the IFN signature in lupus pathogenesis.

Emerging therapies for systemic lupus erythematosus--focus on targeting interferon-alpha

Current therapies for systemic lupus erythematosus (SLE), a debilitating, potentially lethal, multifactorial systemic autoimmune disease, are limited to suppressing disease activity and are associated with multiple adverse effects. Recent advances in basic and translational sciences have elucidated a crucial role for the interferon-alpha (IFNα) pathway in the pathogenesis of this enigmatic disease. The so-called "type I interferon signature" has emerged as a major risk factor for disease activity of SLE. Multiple genes encoding for molecules within the type I interferon pathway have been associated with SLE in genome wide association studies. In addition, innate immune receptors are thought to be triggered by either endogenous and/or exogenous stimuli that lead to hypersecretion of IFNα. We review the multiple emerging treatment strategies targeting IFNα-related pathways. These include monoclonal antibodies against IFNα, anti-IFNα antibody-inducing vaccines, and inhibitors of Toll-like receptors. We also summarize the current status of these pharmaceutical agents in early clinical trials.

IRF5 haplotypes demonstrate diverse serological associations which predict serum interferon alpha activity and explain the majority of the genetic association with systemic lupus erythematosus

OBJECTIVE

High serum interferon α (IFNα) activity is a heritable risk factor for systemic lupus erythematosus (SLE). Auto-antibodies found in SLE form immune complexes which can stimulate IFNα production by activating endosomal Toll-like receptors and interferon regulatory factors (IRFs), including IRF5. Genetic variation in IRF5 is associated with SLE susceptibility; however, it is unclear how IRF5 functional genetic elements contribute to human disease.

METHODS

1034 patients with SLE and 989 controls of European ancestry, 555 patients with SLE and 679 controls of African-American ancestry, and 73 patients with SLE of South African ancestry were genotyped at IRF5 polymorphisms, which define major haplotypes. Serum IFNα activity was measured using a functional assay.

RESULTS

In European ancestry subjects, anti-double-stranded DNA (dsDNA) and anti-Ro antibodies were each associated with different haplotypes characterised by a different combination of functional genetic elements (OR>2.56, p<1.9×10(-14) for both). These IRF5 haplotype-auto-antibody associations strongly predicted higher serum IFNα in patients with SLE and explained >70% of the genetic risk of SLE due to IRF5. In African-American patients with SLE a similar relationship between serology and IFNα was observed, although the previously described European ancestry-risk haplotype was present at admixture proportions in African-American subjects and absent in African patients with SLE.

CONCLUSIONS

The authors define a novel risk haplotype of IRF5 that is associated with anti-dsDNA antibodies and show that risk of SLE due to IRF5 genotype is largely dependent upon particular auto-antibodies. This suggests that auto-antibodies are directly pathogenic in human SLE, resulting in increased IFNα in cooperation with particular combinations of IRF5 functional genetic elements. SLE is a systemic autoimmune disorder affecting multiple organ systems including the skin, musculoskeletal, renal and haematopoietic systems. Humoral autoimmunity is a hallmark of SLE, and patients frequently have circulating auto-antibodies directed against dsDNA, as well as RNA binding proteins (RBP). Anti-RBP autoantibodies include antibodies which recognize Ro, La, Smith (anti-Sm), and ribonucleoprotein (anti-nRNP), collectively referred to as anti-retinol-binding protein). Anti-retinol-binding protein and anti-dsDNA auto-antibodies are rare in the healthy population. These auto-antibodies can be present in sera for years preceding the onset of clinical SLE illness and are likely pathogenic in SLE.

Effects of IRF5 lupus risk haplotype on pathways predicted to influence B cell functions

Both genetic and environmental interactions affect systemic lupus erythematosus (SLE) development and pathogenesis. One known genetic factor associated with lupus is a haplotype of the interferon regulatory factor 5 (IRF5) gene. Analysis of global gene expression microarray data using gene set enrichment analysis identified multiple interferon- and inflammation-related gene sets significantly overrepresented in cells with the risk haplotype. Pathway analysis using expressed genes from the significant gene sets impacted by the IRF5 risk haplotype confirmed significant correlation with the interferon pathway, Toll-like receptor pathway, and the B-cell receptor pathway. SLE patients with the IRF5 risk haplotype have a heightened interferon signature, even in an unstimulated state (P = 0.011), while patients with the IRF5 protective haplotype have a B cell interferon signature similar to that of controls. These results identify multiple genes in functionally significant pathways which are affected by IRF5 genotype. They also establish the IRF5 risk haplotype as a key determinant of not only the interferon response, but also other B-cell pathways involved in SLE.