Gene Expression Profiles from Disease Discordant Twins Suggest Shared Antiviral Pathways and Viral Exposures among Multiple Systemic Autoimmune Diseases

Association of anti-HSC70 autoantibodies with cutaneous ulceration and severe disease in juvenile dermatomyositis

OBJECTIVES

JDM is an inflammatory myopathy characterized by prominent vasculopathy. AECAs are frequently detected in inflammatory and autoimmune diseases. We sought to determine whether AECAs correlate with clinical features of JDM, and thus serve as biomarkers to guide therapy or predict outcome.

METHODS

Plasma samples from 63 patients with JDM, 49 patients with polyarticular JIA and 40 juvenile healthy controls were used to detect anti-heat shock cognate 71 kDa protein (HSC70) autoantibodies, a newly identified AECA, in ELISA assays. Clinical features were compared between JDM patients with and without anti-HSC70 autoantibodies.

RESULTS

Anti-HSC70 autoantibodies were detected in 35% of patients with JDM, in 0% of patients with JIA (P < 0.0001) and in 0% of healthy donors (P < 0.0001). Both the presence of cutaneous ulcers (59% vs 17%, P < 0.002) and the use of wheelchairs and/or assistive devices (64% vs 27%, P < 0.007) were strongly associated with anti-HSC70 autoantibodies in JDM. High scores on the severity of myositis damage measures at the time of measurement of anti-HSC70 autoantibodies and an increased number of hospitalizations were also associated with anti-HSC70 autoantibodies. Intravenous immunoglobulin therapy was used more often in anti-HSC70 autoantibody-positive patients.

CONCLUSION

Anti-HCS70 autoantibodies are detected frequently in children with JDM and are novel myositis-associated autoantibodies correlating with disease severity.

Gene expression profiling meta-analysis reveals novel gene signatures and pathways shared between tuberculosis and rheumatoid arthritis

Tuberculosis (TB) is among the leading causes of death by infectious diseases. An epidemiological association between Mycobacterium tuberculosis infection and autoimmune diseases like rheumatoid arthritis (RA) has been reported but it remains unclear if there is a causal relationship, and if so, which molecular pathways and regulatory mechanisms contribute to it. Here we used a computational biology approach by global gene expression meta-analysis to identify candidate genes and pathways that may link TB and RA. Data were collected from public expression databases such as NCBI GEO. Studies were selected that analyzed mRNA-expression in whole blood or blood cell populations in human case control studies at comparable conditions. Six TB and RA datasets (41 active TB patients, 33 RA patients, and 67 healthy controls) were included in the downstream analysis. This approach allowed the identification of deregulated genes that had not been identified in the single analysis of TB or RA patients and that were co-regulated in TB and RA patients compared to healthy subjects. The genes encoding TLR5, TNFSF10/TRAIL, PPP1R16B/TIMAP, SIAH1, PIK3IP1, and IL17RA were among the genes that were most significantly deregulated in TB and RA. Pathway enrichment analysis revealed 'T cell receptor signaling pathway', 'Toll-like receptor signaling pathway,' and 'virus defense related pathways' among the pathways most strongly associated with both diseases. The identification of a common gene signature and pathways substantiates the observation of an epidemiological association of TB and RA and provides clues on the mechanistic basis of this association. Newly identified genes may be a basis for future functional and epidemiological studies.

From HSV infection to erythema multiforme through autoimmune crossreactivity

Scientific and clinical data indicate that human herpes simplex virus 1 (HSV1) and, at a lesser extent, human herpes simplex virus 2 (HSV2) are factor(s) implicated in the development of erythema multiforme (EM). With a focus on oral EM, the present structured review of proteomic and epitope databases searched for the molecular basis that might link HSV1 and HSV2 infections to EM. It was found that a high number of peptides are shared between the two HSVs and human proteins related to the oral mucosa. Moreover, a great number of the shared peptides are also present in epitopes that have been experimentally validated as immunopositive in the human host. The results suggest the involvement of HSV infections in the induction of oral EM via a mechanism of autoimmune cross-reactivity and, in particular, highlight a potential major role for 180kDa bullous pemphigoid antigen and HSV1 infection in the genesis of crossreactions potentially conducive to EM.

Anti-NT5C1A autoantibodies are associated with more severe disease in patients with juvenile myositis

OBJECTIVES

Autoantibodies recognising cytosolic 5'-nucleotidase 1A (NT5C1A) are found in adult patients with myositis and other autoimmune diseases. They are especially prevalent in adults with inclusion body myositis (IBM), in which they are associated with more severe weakness and higher mortality. This study was undertaken to define the prevalence and clinical features associated with anti-NT5C1A autoantibodies in juvenile myositis.

METHODS

We screened sera from 380 patients with juvenile myositis, 30 patients with juvenile idiopathic arthritis (JIA) and 92 healthy control children for anti-NT5C1A autoantibodies. Clinical characteristics were compared between patients with myositis with and without anti-NT5C1A autoantibodies.

RESULTS

Anti-NT5C1A autoantibodies were present in 102 of 380 (27%) patients with juvenile myositis and in 11 of 92 (12%) healthy control children (P=0.002) and 27% of children with JIA (P=0.05 vs controls). Sera of 83 of 307 (27%) patients with juvenile dermatomyositis and 16 of 46 (35%) patients with juvenile overlap myositis were anti-NT5C1A autoantibody-positive (P<0.01 vs healthy controls for each), but sera of only 3 of 27 (11%) patients with juvenile polymyositis were anti-NT5C1A-positive. Patients with juvenile myositis with and without anti-NT5C1A autoantibodies had similar clinical phenotypes. However, patients with anti-NT5C1A autoantibody-positive myositis had greater pulmonary symptoms at diagnosis (P=0.005), more frequent hospitalisations (P=0.01) and required a larger number of medications (P<0.001).

CONCLUSION

Anti-NT5C1A autoantibodies are present in more than one-quarter of children with juvenile myositis and JIA compared with only 12% of healthy children, suggesting they are myositis-associated in children. As in adults with IBM, patients with juvenile myositis with anti-NT5C1A autoantibodies have more severe disease.

Gene Expression Analysis Reveals Novel Shared Gene Signatures and Candidate Molecular Mechanisms between Pemphigus and Systemic Lupus Erythematosus in CD4+ T Cells

Pemphigus and systemic lupus erythematosus (SLE) are severe potentially life-threatening autoimmune diseases. They are classified as B-cell-mediated autoimmune diseases, both depending on autoreactive CD4⁺ T lymphocytes to modulate the autoimmune B-cell response. Despite the reported association of pemphigus and SLE, the molecular mechanisms underlying their comorbidity remain unknown. Weighted gene co-expression network analysis (WGCNA) of publicly available microarray datasets of CD4⁺ T cells was performed, to identify shared gene expression signatures and putative overlapping biological molecular mechanisms between pemphigus and SLE. Using WGCNA, we identified 3,280 genes co-expressed genes and 14 co-expressed gene clusters, from which one was significantly upregulated for both diseases. The pathways associated with this module include type-1 interferon gamma and defense response to viruses. Network-based meta-analysis identified RSAD2 to be the most highly ranked hub gene. By associating the modular genes with genome-wide association studies (GWASs) for pemphigus and SLE, we characterized IRF8 and STAT1 as key regulatory genes. Collectively, in this in silico study, we identify novel candidate genetic markers and pathways in CD4⁺ T cells that are shared between pemphigus and SLE, which in turn may facilitate the identification of novel therapeutic targets in these diseases.

New insights into the immunopathogenesis of systemic lupus erythematosus

The aetiology of systemic lupus erythematosus (SLE) is multifactorial, and includes contributions from the environment, stochastic factors, and genetic susceptibility. Great gains have been made in understanding SLE through the use of genetic variant identification, mouse models, gene expression studies, and epigenetic analyses. Collectively, these studies support the concept that defective clearance of immune complexes and biological waste (such as apoptotic cells), neutrophil extracellular traps, nucleic acid sensing, lymphocyte signalling, and interferon production pathways are all central to loss of tolerance and tissue damage. Increased understanding of the pathogenesis of SLE is driving a renewed interest in targeted therapy, and researchers are now on the verge of developing targeted immunotherapy directed at treating either specific organ system involvement or specific subsets of patients with SLE. Accordingly, this Review places these insights within the context of our current understanding of the pathogenesis of SLE and highlights pathways that are ripe for therapeutic targeting.