African swine fever virus I267L acts as an important virulence factor by inhibiting RNA polymerase III-RIG-I-mediated innate immunity.

ASFV is a large DNA virus that is highly pathogenic in domestic pigs. How this virus is sensed by the innate immune system as well as why it is so virulent remains enigmatic. In this study, we show that the ASFV genome contains AT-rich regions that are recognized by the DNA-directed RNA polymerase III (Pol-III), leading to viral RNA sensor RIG-I-mediated innate immune responses. We further show that ASFV protein I267L inhibits RNA Pol-III-RIG-I-mediated innate antiviral responses. I267L interacts with the E3 ubiquitin ligase Riplet, disrupts Riplet-RIG-I interaction and impairs Riplet-mediated K63-polyubiquitination and activation of RIG-I. I267L-deficient ASFV induces higher levels of interferon-ß, and displays compromised replication both in primary macrophages and pigs compared with wild-type ASFV. Furthermore, I267L-deficiency attenuates the virulence and pathogenesis of ASFV in pigs. These findings suggest that ASFV I267L is an important virulence factor by impairing innate immune responses mediated by the RNA Pol-III-RIG-I axis.

Molecular basis for clinical diversity between autoantibody subsets in diffuse cutaneous systemic sclerosis.

OBJECTIVES: Clinical heterogeneity is a cardinal feature of systemic sclerosis (SSc). Hallmark SSc autoantibodies are central to diagnosis and associate with distinct patterns of skin-based and organ-based complications. Understanding molecular differences between patients will benefit clinical practice and research and give insight into pathogenesis of the disease. We aimed to improve understanding of the molecular differences between key diffuse cutaneous SSc subgroups as defined by their SSc-specific autoantibodies METHODS: We have used high-dimensional transcriptional and proteomic analysis of blood and the skin in a well-characterised cohort of SSc (n=52) and healthy controls (n=16) to understand the molecular basis of clinical diversity in SSc and explore differences between the hallmark antinuclear autoantibody (ANA) reactivities. RESULTS: Our data define a molecular spectrum of SSc based on skin gene expression and serum protein analysis, reflecting recognised clinical subgroups. Moreover, we show that antitopoisomerase-1 antibodies and anti-RNA polymerase III antibodies specificities associate with remarkably different longitudinal change in serum protein markers of fibrosis and divergent gene expression profiles. Overlapping and distinct disease processes are defined using individual patient pathway analysis. CONCLUSIONS: Our findings provide insight into clinical diversity and imply pathogenetic differences between ANA-based subgroups. This supports stratification of SSc cases by ANA antibody subtype in clinical trials and may explain different outcomes across ANA subgroups in trials targeting specific pathogenic mechanisms.

TDP-43 prevents endogenous RNAs from triggering a lethal RIG-I-dependent interferon response.

RIG-I-like receptors (RLRs) are involved in the discrimination of self versus non-self via the recognition of double-stranded RNA (dsRNA). Emerging evidence suggests that immunostimulatory dsRNAs are ubiquitously expressed but are disrupted or sequestered by cellular RNA binding proteins (RBPs). TDP-43 is an RBP associated with multiple neurological disorders and is essential for cell viability. Here, we demonstrate that TDP-43 regulates the accumulation of immunostimulatory dsRNA. The immunostimulatory RNA is identified as RNA polymerase III transcripts, including 7SL and Alu retrotransposons, and we demonstrate that the RNA-binding activity of TDP-43 is required to prevent immune stimulation. The dsRNAs activate a RIG-I-dependent interferon (IFN) response, which promotes necroptosis. Genetic inactivation of the RLR-pathway rescues the interferon-mediated cell death associated with loss of TDP-43. Collectively, our study describes a role for TDP-43 in preventing the accumulation of endogenous immunostimulatory dsRNAs and uncovers an intricate relationship between the control of cellular gene expression and IFN-mediated cell death.

RNA polymerase III and antiviral innate immune response.

The innate immune system has numerous signal transduction pathways that lead to the production of type I interferons in response to exposure of cells to external stimuli. One of these pathways comprises RNA polymerase (Pol) III that senses common DNA viruses, such as cytomegalovirus, vaccinia, herpes simplex virus-1 and varicella zoster virus. This polymerase detects and transcribes viral genomic regions to generate AU-rich transcripts that bring to the induction of type I interferons. Remarkably, Pol III is also stimulated by foreign non-viral DNAs and expression of one of its subunits is induced by an RNA virus, the Sindbis virus. Moreover, a protein subunit of RNase P, which is known to associate with Pol III in initiation complexes, is induced by viral infection. Accordingly, alliance of the two tRNA enzymes in innate immunity merits a consideration.

Association of differentially expressed genes and autoantibody type in patients with systemic sclerosis.

OBJECTIVES: The aims of this study were to investigate the relationship between the type of autoantibody and gene expression profile in skin lesions from patients with SSc, and to identify specific dysregulated pathways in SSc patients compared with healthy controls. METHODS: Sixty-one patients with SSc from the Genetics vs Environment in Scleroderma Outcome Study cohort and 36 healthy controls were included in this study. Differentially expressed genes were extracted and functional enrichment and pathway analysis were conducted. RESULTS: Compared with healthy controls, lists containing 2, 71, 10, 144 and 78 differentially expressed genes were created for patients without specific autoantibody, ACA, anti-U1 RNP antibody (RNP), anti-RNA polymerase III antibody (RNAP) and anti-topoisomerase I antibody (ATA), respectively. While part of the enriched pathways overlapped, distinct pathways were identified except in those patients lacking specific autoantibody. The distinct enriched pathways included 'keratinocyte differentiation' for ACA, 'nuclear factor κB signalling' and 'cellular response to TGF-ß stimulus' for RNAP, 'interferon α/ß signalling' for RNP, and 'cellular response to stress' for ATA. Cell type signature score analysis revealed that macrophages/monocytes, endothelial cells and fibroblasts were associated with ACA, RNAP, ATA and the severity of the SSc skin lesions. CONCLUSION: Pathogenic pathways were identified according to the type of autoantibody by leveraging gene expression data of patients and controls from a multicentre cohort. The current study may promote the search for new therapeutic targets for SSc.

Diffuse alveolar haemorrhage in a case with anti-RNA polymerase III antibody-positive systemic sclerosis successfully treated with plasma exchange and corticosteroid therapy.

A 63-year-old woman was admitted because of diffuse alveolar haemorrhage complicated with systemic sclerosis. High anti-RNA polymerase III (RNAP III) antibody titre was detected despite normal blood pressure and renal function. Antibodies other than anti-RNAP III antibody were negative. After initiation of methyl-prednisolone pulse therapy, the patient developed thrombotic microangiopathy (TMA) with exacerbation of respiratory failure, which required mechanical ventilation. However, renal function was preserved. We immediately started the patient on plasma exchange; subsequently, her diffuse alveolar haemorrhage and TMA dramatically improved. Diffuse alveolar haemorrhage with systemic sclerosis is generally occurred as pulmonary renal syndrome, and positive anti-RNAP III antibody is recognised as a predictive marker of scleroderma renal crisis. However, this case suggests that high anti-RNAP III antibody titre may play a role in the development of diffuse alveolar haemorrhage without scleroderma renal crisis.

Clonal haematopoiesis is increased in early onset in systemic sclerosis.

OBJECTIVES: SSc is an autoimmune disease characterized by fibrosis, microangiopathy and immune dysfunctions including dysregulation of proinflammatory cytokines. Clonal haematopoiesis of indeterminate potential (CHIP) is defined by the acquisition of somatic mutations in haematopoietic stem cells leading to detectable clones in the blood. Recent data have shown a higher risk of cardiovascular disease in patients with CHIP resulting from increased production of proinflammatory cytokines and accelerated atherosclerosis. Eventual links between CHIP and autoimmune diseases are undetermined. The aim of our study was to evaluate the prevalence of CHIP in SSc patients and its association with clinical phenotype. METHODS: Forty-one genes frequently mutated in myeloid malignancies were sequenced in peripheral blood mononuclear cells from 90 SSc patients and 44 healthy donors. RESULTS: A total of 15 somatic variants were detected in 13/90 SSc patients (14%) and four somatic variants in 4/44 (9%) healthy donors (HD) (P = 0.58). The prevalence of CHIP was significantly higher in younger SSc patients than in HD: 25% (6/24) vs 4% (1/26) (P = 0.045) under 50 years and 17% (7/42) vs 3% (1/38) (P = 0.065) under 60 years. The prevalence of CHIP in patients over 70 years was similar in SSc patients and healthy donors. The most common mutations occurred in DNMT3A (seven variants). No major clinical differences were observed between SSc patients with or without CHIP. CONCLUSION: Whether CHIP increases the risk to develop SSc or is a consequence of a SSc-derived modified bone marrow micro-environment remains to be explored.

Expert Perspectives On Clinical Challenges: Expert Perspectives: Challenges in Scleroderma.

You are consulted to evaluate a 56-year-old woman with known Raynaud's phenomenon, finger swelling of several; months' duration, and new hypertension with a blood pressure of 160/100 mm/Hg. She also reports progressive shortness of breath. Physical examination reveals telangiectasias, sclerodactyly, and proximal skin sclerosis (thick shiny skin on the chest and upper arms), and bibasilar crackles are found on chest examination. Laboratory tests reveal evidence of microangiopathic hemolytic anemia, thrombocytopenia, and elevation of the serum creatinine level (previously normal), and chest computed tomography shows evidence of ground-glass opacification in both lower lung fields.

[A case of systemic sclerosis]. / U ne rémission « en peau de chagrin ¼.

In systemic sclerosis, the presence of an anti-RNA polymerase III antibody (ARNpol3) is associated with an increased risk of cancer. The characteristic picture of this serotype includes severe diffuse cutaneous involvement, a high risk of renal scleroderma crisis and a 10 year survival of only around 30%. Pulmonary involvement is less common. We report the case of a woman initially treated for drug-induced acute interstitial lung disease revealing chronic interstitial pneumonia with autoimmune features. The disease evolved in three stages with the occurrence of a rapidly progressive diffuse skin sclerosis with anti-ARNPol3 antibodies in the context of ovarian cancer remission.

Analysis of Anti-RNA Polymerase III Antibody-positive Systemic Sclerosis and Altered GPATCH2L and CTNND2 Expression in Scleroderma Renal Crisis.

OBJECTIVE: Scleroderma renal crisis (SRC) is a life-threatening complication of systemic sclerosis (SSc) strongly associated with anti-RNA polymerase III antibody (ARA) autoantibodies. We investigated genetic susceptibility and altered protein expression in renal biopsy specimens in ARA-positive patients with SRC. METHODS: ARA-positive patients (n = 99) with at least 5 years' follow-up (49% with a history of SRC) were selected from a well characterized SSc cohort (n = 2254). Cases were genotyped using the Illumina Human Omni-express chip. Based on initial regression analysis, 9 single-nucleotide polymorphisms (SNP) were chosen for validation in a separate cohort of 256 ARA-positive patients (40 with SRC). Immunostaining of tissue sections from SRC or control kidney was used to quantify expression of candidate proteins based upon genetic analysis of the discovery cohort. RESULTS: Analysis of 641,489 SNP suggested association of POU2F1 (rs2093658; P = 1.98 × 10-5), CTNND2 (rs1859082; P = 5.58 × 10-5), HECW2 (rs16849716; P = 1.2 × 10-4), and GPATCH2L (rs935332; P = 4.92 × 10-5) with SRC. Further, the validation cohort showed an association between rs935332 within the GPATCH2L region, with SRC (P = 0.025). Immunostaining of renal biopsy sections showed increased tubular expression of GPATCH2L (P = 0.026) and glomerular expression of CTNND2 (P = 0.026) in SRC samples (n = 8) compared with normal human kidney controls (n = 8), despite absence of any genetic replication for the associated SNP. CONCLUSION: Increased expression of 2 candidate proteins, GPATCH2L and CTNND2, in SRC compared with control kidney suggests a potential role in pathogenesis of SRC. For GPATCH2L, this may reflect genetic susceptibility in ARA-positive patients with SSc based upon 2 independent cohorts.

Analysis of anti-RNA polymerase III antibodies in Chinese Han systemic sclerosis patients.

OBJECTIVES: This study aimed to assess the prevalence and clinical correlation of anti-RNA polymerase III antibodies (anti-RNAP III) in Chinese Han systemic sclerosis (SSc) patients. METHODS: Serum samples from 236 patients with SSc, 125 patients with connective tissue diseases (CTD), and 166 healthy controls (HCs), recruited from Peking Union Medical College Hospital and 21 other medical centers in China, were tested for antibodies to RNA polymerase III by means of a line immunoassay (LIA) or an enzyme-linked immunosorbent assay (ELISA) kit. RESULTS: Anti-RNAP III antibodies were found in 14/236 SSc patients (5.93%), 1/125 (0.80%) CTD patients, and 0/166 (0.00%) HCs. The prevalence of anti-RNAP III was higher in SSc patients than in the CTD and HC groups (p = 0.02, p = 0.001, respectively). Renal crisis was significantly more common in patients with anti-RNAP III than patients without anti-RNAP III (42.9 vs. 4.1%, p < 0.0001). Gastrointestinal involvement was significantly more common in patients without anti-RNAP III than patients with anti-RNAP III (53.6 vs. 21.4%, p = 0.039). There was good agreement between the ELISA and line immunoassay (LIA) detection capabilities for anti-RNAP III. CONCLUSIONS: The anti-RNAP III antibody, which was detected by ELISA, has diagnostic value for SSc and predictive value for SSc-related renal crisis. Both ELISA and LIA are very reliable methods for anti-RNAP III.Key Points• The prevalence of anti-RNAP III antibody was determined in Chinese SSc patients and performed ethnic differences.• The clinical association between anti-RNAP III antibody and Chinese SSc patients was evaluated in this research.• Methodological consistency of detection of anti-RNAP III antibody using commercial ELISA and LIA methods was evaluated in this research.

Late onset systemic sclerosis with seronegativity: a rare presentation of an uncommon disease.

Systemic sclerosis (SSc) is an uncommon connective tissue disorder characterized by multisystem involvement with fibrosis of skin and internal organs. Antibody formation is one of the hallmarks of SSc. Antinuclear antibodies (ANA) are positive in 97% of patients with SSc. We report a rare case where the patient was negative for ANA, Anti-topoisomerase I, Anti-centromere and Anti-RNA polymerase III antibodies.

TNFA -308G>A and -238G>A polymorphisms and risk to systemic sclerosis: impact on TNF-α serum levels, TNFA mRNA expression, and autoantibodies.

Systemic sclerosis (SSc) is a rare autoimmune disease with high mortality, characterized by chronic inflammation and fibrosis, which are processes associated with higher serum tumor necrosis factor-α (sTNF-α) levels. TNFA -308G>A and -238G>A polymorphisms have been associated with higher sTNF-α levels. In this study, we genotyped the TNFA -308G>A and -238G>A polymorphisms in 53 SSc patients and 115 unrelated control subjects (CS) from southern Mexico. The TNFA mRNA expression and sTNF-α levels were also quantified by qPCR and enzyme-linked immunosorbent assays, respectively. TNFA -308GA genotype was associated with disease susceptibility according to a codominant genetic model (OR = 3.2, 95% CI 1.05-9.75, p = 0.03), and with higher anti-fibrillarin antibodies (p = 0.01), and higher skin thickening (p = 0.006). TNFA -238GA was not associated with SSc risk. TNFA mRNA expression and sTNF-α levels were similar between SSc patients and CS and were not statistically associated with the TNFA polymorphisms; however, a correlation (rho = 0.362, p = 0.009) between sTNF-α levels with anti-RNA polymerase III antibodies was observed in the SSc patients. In conclusion, the -308G>A polymorphism is a genetic marker of SSc susceptibility in population from southern Mexico, and it is associated with skin thickening and anti-fibrillarin antibodies. In addition, sTNF-α levels correlate positively with the anti-RNA pol III antibodies levels.

Anti-RNA polymerase III antibody in lupus patients with proteinuria.

BACKGROUND: To investigate the relationship between serum anti-ribonucleic acid polymerase III (anti-RNAP3) autoantibodies (Abs) and proteinuria severity in lupus patients. METHODS: Serum antibodies reacting with anti-RNAP3 were measured in 49 systemic lupus erythematosus (SLE) patients (29 cases of SLE with proteinuria and 20 cases of SLE without proteinuria) and 10 healthy controls (HCs). For the patients, we recorded demographic data, daily urinary protein loss, serum anti-double strand deoxyribonucleic acid (anti-ds-DNA) antibodies, serum creatinine (Cr), estimated glomerular filtrating rate (eGFR), complement 3 (C3), and C4. RESULTS: Fewer anti-RNAP3 antibodies were found in the SLE patients than in the HCs (p = 0.061). In the SLE with proteinuria group, positive correlations were observed among anti-RNAP3 antibodies and daily urinary protein loss, serum C3, C4, and eGFR, and negative correlations were observed between anti-RNAP3-Abs and anti-ds-DNA-Abs and serum Cr levels. However, these correlations were nonsignificant (p > 0.05). CONCLUSION: This study demonstrated the possible role of anti-RNAP3 antibodies in SLE patients with proteinuria, as evidenced by their positive and negative relationships with daily urinary protein loss, eGFR, C3, C4, serum Cr, and anti-ds-DNA-Abs. Although these correlations were nonsignificant, our study builds a foundation for future tailored studies, and more in-depth studies with larger samples are warranted to provide more information.

Protective Effect Against Cancer of Antibodies to the Large Subunits of Both RNA Polymerases I and III in Scleroderma.

OBJECTIVE: While compelling data suggest a cancer-induced autoimmunity model in scleroderma patients with anti-RNA polymerase III large subunit (anti-RPC155) antibodies, ~85% of these patients do not manifest cancer. This study was undertaken to determine whether additional autoantigens are targeted in anti-RPC155-positive scleroderma patients without detectable cancer. METHODS: The study included 168 scleroderma patients with anti-RPC155 antibodies (80 with a history of cancer and 88 with no cancer diagnosis after >5 years of follow-up). Thirty-five sera (17 from patients with cancer and 18 from patients without cancer) were randomly selected for autoantibody discovery using immunoprecipitation (IP). An ~194-kd band was enriched in the subgroup without cancer; this was identified as RNA polymerase I large subunit (RPA194). RESULTS: RPA194 generated by in vitro transcription/translation was used for IPs performed on the entire cohort to test whether anti-RPA194 was enriched among anti-RPC155-positive patients without cancer. Anti-RPA194 antibodies were significantly more common in the group without cancer (16 [18.2%] of 88) than in the group with cancer (3 [3.8%] of 80) (P = 0.003). Patients with both anti-RPA194 and anti-RPC155 were significantly less likely to have severe gastrointestinal disease than patients with anti-RPC155 only (26.3% versus 51.0%; P = 0.043). CONCLUSION: Anti-RPA194 antibodies are enriched in anti-RPC155-positive scleroderma patients without cancer. Since somatic mutations in the gene encoding RPC155 in cancer in scleroderma patients appears to play a role in immune response initiation against RPC155 in those patients, these data raise the possibility that the development of immune responses to both RPC155 and RPA194 may influence clinical cancer emergence. Further study is required to define whether different autoantibody combinations have utility as tools for cancer risk stratification in scleroderma.

Clinical features of systemic sclerosis patients with anti-RNA polymerase III antibody in a single centre in Spain.

OBJECTIVES: To evaluate the clinical features and survival of patients with positive anti-RNA polymerase III (anti-RNAP III) in a Spanish single centre. METHODS: We analysed 221 patients with SSc according to LeRoy and Medsger criteria. Twenty-six patients with positivity for anti-RNAP III antibodies were compared with 195 negative patients. Epidemiological, clinical, immunological features and survival were analysed. RESULTS: In patients with anti-RNAP III positivity diffuse cutaneous SSc (dcSSc) subset was the most prevalent (20, 76.9% vs. 35, 17.9%, p < 0.001), with shorter diagnosis delay (4.11 ± 7.34 years vs. 6.77 ± 9.22 years, p = 0.005). Patients with anti-RNAP III antibodies had higher frequency of arterial hypertension (13, 50% vs. 55, 28.2%, p = 0.024), scleroderma renal crisis (SRC) (3, 11.5% vs. 3, 1.5%, p = 0.023), arthritis (9, 34.6% vs. 35, 17.9%, p = 0.046), tendon friction rubs (4, 15.4% vs. 1, 0.5%, p = 0.001) and contractures (5, 19.2% vs. 10, 5.1%, p = 0.02). There were no differences found in the presence of cancer or in global survival. In the multivariate survival analysis, severe interstitial lung disease (ILD) (HR: 8.61, 95%CI 3.40 - 21.81), pulmonary arterial hypertension (PAH) (HR: 4.05, 95%CI 1.42 - 11.61) and SRC (HR: 17.27, 95%CI 3.36 - 88.97) were the only factors associated with poor prognosis. CONCLUSIONS: In this cohort anti-RNAP III antibodies are related with dcSSc subset, shorter diagnostic delay and higher prevalence of musculoskeletal involvement, arterial hypertension and SRC. ILD, PAH and SRC were independent prognostic factors.

Elevated kynurenine levels in diffuse cutaneous and anti-RNA polymerase III positive systemic sclerosis.

Systemic sclerosis (SSc) is a systemic disease characterized by vasculopathy, progressive fibrosis and autoimmune activation. Tryptophan (Trp) metabolism has been linked to altered immune cell function and to malignancy. We have investigated the role of Trp metabolic pathway in SSc measuring serum Trp, Kynurenine (Kyn) and Trp/Kyn ratio in a cohort of 97 SSc patients and 10 healthy controls. Association with disease characteristics was evaluated. We found that Trp levels in SSc patients were significantly lower compared to HCs. We also found that patients with diffuse cutaneous (dcSSc) had lower levels of Trp compared to limited cutaneous (lcSSc). These results were paralleled by higher levels of Kyn found in SSc patients compared to HCs and significantly lower levels in dcSSc compared to lcSSc. The autoantibody profile was also found to be significantly associated with Kyn and Trp levels as anti-RNA-polymerase III (ARA) positive patients were shown to have lower Trp levels and higher Kyn levels compared with anti-centromere and anti-topoisomerase I positive patients. Moreover, the highest Trp/Kyn was found in ARA+ patients with dcSSc, suggesting that an activation of the Kyn pathway, is more specifically associated with this subset of SSc patients. Stability over time makes these markers of Trp metabolism feasible for SSc stratification.

Risk Factors for Future Scleroderma Renal Crisis at Systemic Sclerosis Diagnosis.

OBJECTIVE: Systemic sclerosis (SSc) is a disease of autoimmunity, fibrosis, and vasculopathy. Scleroderma renal crisis (SRC) is one of the most severe complications. Corticosteroid exposure, presence of anti-RNA polymerase III antibodies (ARA), skin thickness, and significant tendon friction rubs are among the known risk factors at SSc diagnosis for developing future SRC. Identification of additional clinical characteristics and laboratory findings could expand and improve the risk profile for future SRC at SSc diagnosis. METHODS: In this retrospective cohort study of the entire military electronic medical record between 2005 and 2016, we compared the demographics, clinical characteristics, and laboratory results at SSc diagnosis for 31 cases who developed SRC after SSc diagnosis to 322 SSc without SRC disease controls. RESULTS: After adjustment for potential confounding variables, at SSc diagnosis these conditions were all associated with future SRC: proteinuria (p < 0.001; OR 183, 95% CI 19.1-1750), anemia (p = 0.001; OR 9.9, 95% CI 2.7-36.2), hypertension (p < 0.001; OR 13.1, 95% CI 4.7-36.6), chronic kidney disease (p = 0.008; OR 20.7, 95% CI 2.2-190.7), elevated erythrocyte sedimentation rate (p < 0.001; OR 14.3, 95% CI 4.8-43.0), thrombocytopenia (p = 0.03; OR 7.0, 95% CI 1.2-42.7), hypothyroidism (p = 0.01; OR 2.8, 95% CI 1.2-6.7), Anti-Ro antibody seropositivity (p = 0.003; OR 3.9, 95% CI 1.6-9.8), and ARA (p = 0.02; OR 4.1, 95% CI 1.2-13.8). Three or more of these risk factors present at SSc diagnosis was sensitive (77%) and highly specific (97%) for future SRC. No SSc without SRC disease controls had ≥ 4 risk factors. CONCLUSION: In this SSc cohort, we present a panel of risk factors for future SRC. These patients may benefit from close observation of blood pressure, proteinuria, and estimated glomerular filtration rate, for earlier SRC identification and intervention. Future prospective therapeutic studies could focus specifically on this high-risk population.