Abstract Background Cardiac involvement in Systemic Sclerosis (SSc) is common, with manifestations ranging from subclinical to life-threatening 1. Cardiopulmonary complications, including, right ventricular (RV) dysfunction is the leading cause of SSc-related mortality2. Pulmonary arterial hypertension (PAH) occurs in 8-12% of SSc patients and remains a leading cause of death, with a 3-year survival rate around 50%2. The progressive decline in RV function in PAH is often attributed to RV ischemia3. Oxygen Sensitive Cardiac Magnetic Resonance imaging (OS-CMR) has been previously used by our group to assess RV myocardial oxygenation in patients with PAH3, including SSc-associated PAH 3. The objective of this study was to use OS-CMR to assess RV myocardial oxygenation in SSc patients prior to the onset of PAH. Methodology In this prospective, multicentre study, three study groups were established. Group 1 comprised SSc patients without PAH or known cardiac disease. Group 2 included stable PAH patients confirmed by right heart catheterization, matched for age and sex, but without SSc. Group 3 comprised healthy normal volunteers (NV), matched for age and sex. All patients underwent a 3T CMR which included: cine images, rest cine OS-CMR, stress cine OS-CMR, native T1 mapping, stress perfusion, and late gadolinium enhancement (LGE). The primary outcome was change in inferior RV myocardial signal intensity (SI) in diastole, measured by the change in OS-CMR between rest and stress within each group. Two experienced independent reviewers performed the CMR analysis with an inter-assessor correlation coefficient of 0.8, 95% Cl [0.3, 0.9]. Results A total of 44 patients were enrolled. Of these, n=26 group 1 (SSc), n=8 group 2 (PAH), n=10 group 3 (NV). Study results are listed in Table 1. Mean age within the SSc, PAH, and NV groups were 59±10, 67±12 and 57 ±7 years respectively (p=0.482). The RV OS-CMR SI was significantly lower in the SSc group when compared to the NV group (p=0.017). In contrast, there was no significant difference between the PAH and SSc groups (p=0.426), indicating a similar degree of RV ischemia in the established PAH patients and the SSc patients. All SSc patients exhibited inferior and anterior RV insertion fibrosis, with no perfusion defects noted. Five (19%) of SSc patients presented with LGE hyperenhancement in the LV. Eighteen (69%) of SSc patients obtained at least 1 abnormal T1 mapping segment in the LV. Conclusion SSc patients without overt PAH had a similar degree of RV ischemia when compared to patients with overt PAH from other causes. Our findings imply that in SSc, RV adverse effects occur prior to the onset of PAH, and that this effect is mediated by RV ischemia secondary to changes in the microvasculature. Our findings may have screening and/or therapeutic implications.

Objective To evaluate the predictive accuracy of the Australian Scleroderma Interest Group (ASIG) algorithm and the DETECT algorithm to identify pulmonary arterial hypertension (PAH) in an Australian systemic sclerosis (SSc) cohort. Methods Algorithm performance evaluated using prospectively collected data from a cohort with annual serum NT-proBNP, TTE and RFT. Results From 2009 - 2022, 243 patients had sufficient data to apply both algorithms; 52 underwent right heart catheterisation (RHC), 33 were diagnosed with PAH (13.6%). The ASIG algorithm was positive in 105 patients (43.21%), 29 were diagnosed with PAH (27.62%). The DETECT algorithm was positive in 172 patients (70.78%), 30 were diagnosed with PAH (17.44%). The sensitivity of the ASIG algorithm for PAH was 87.88% (95% CI 71.80 – 96.60) and specificity was 31.58% (95% CI 12.58 – 56.55); the DETECT algorithm sensitivity was 90.91% (95% CI 75.67 – 98.08). Specificity and negative predictive value (NPV) of the DETECT algorithm were not able to be calculated as there were no true negative DETECT screen cases. The positive predictive value (PPV) of the ASIG algorithm was 69.05% (95% CI 52.91 – 82.38) and NPV was 60.00% (95% CI 26.24 – 87.84); DETECT algorithm PPV was 61.22% (95% CI 46.24 – 74.80). Three cases of PAH were not identified by either algorithm; all had co-existent interstitial lung disease (ILD). Conclusions ASIG and DETECT screening algorithms for PAH perform well in SSc. A small number of false negative screens in patients with ILD highlight the need to interpret PAH screens in SSc-ILD patients with caution.

OBJECTIVES To examine the incidence, predictors and outcomes associated with severe gastrointestinal (GI) disease in a large inception SSc cohort. METHODS SSc subjects with <2 years of disease duration were identified from two multicentre cohorts. Severe GI disease was defined as: malabsorption, hyperalimentation, pseudo-obstruction and/or ⩾10% weight loss in association with the use of antibiotics for bacterial overgrowth or oesophageal stricture. Kaplan-Meier, multivariate logistic regression and Cox proportional hazard analyses were performed to determine the cumulative incidence rate, independent clinical correlates and mortality rate associated with severe GI disease. A longitudinal mixed model was used to assess the impact of severe GI disease on the Short Form Health Survey. RESULTS In this inception SSc cohort, the probability of developing severe GI disease was estimated at 9.1% at 2 years and 16.0% at 4 years. In multivariate analysis, severe GI disease was associated with inflammatory myositis (odds ratio 4.68, 95% CI 1.65, 13.24), telangiectasias (odds ratio 2.45, 95% CI 1.19, 5.04) and modified Rodnan skin score (odds ratio 1.03, 95% CI 1.01, 1.07). Severe GI disease was associated with a >2-fold increase in the risk of death (hazard ratio 2.27, 95% CI 1.27, 4.09) and worse health-related quality of life [Short Form Health Survey physical (β = -2.37, P = 0.02) and mental (β = -2.86, P = 0.01) component summary scores]. CONCLUSION Severe GI disease is common in early SSc and is associated with significant morbidity and increased mortality. More research is needed to understand, prevent and mitigate severe GI disease in SSc.

OBJECTIVES:The role of the erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) in the assessment of disease activity in systemic sclerosis (SSc) remains controversial. We sought to evaluate the relationship between clinical features of SSc and raised inflammatory markers and to determine if changes in ESR and CRP reflect changes in other disease features over time. METHODS:One thousand, five hundred and forty-five patients enrolled in the Australian Scleroderma Cohort Study were observed over a mean 3.52±2.91 years and assessed at 6,119 study visits. Generalised estimating equations were used to determine the relationship between ESR≥20mm/hr and CRP≥5mg/L and features of disease. The associations between change in inflammatory markers and change in skin scores and respiratory function tests were analysed. RESULTS:Overall, there was a significant association between raised ESR and forced vital capacity (FVC)<80% predicted, diffusing capacity of the lung (DLCO)<80% predicted, pulmonary arterial hypertension (PAH), body mass index (BMI), proximal muscle strength, anaemia, and hypocomplementaemia (p<0.05). Raised CRP was significantly associated with modified Rodnan Skin Score>20, FVC<80%, DLCO<80%, PAH, digital ulcers, BMI, synovitis, tendon friction rub, anaemia, and hypocomplementaemia (p<0.05). A significant deterioration in respiratory function tests (RFTs) was associated with a 2-fold increase in both ESR and CRP (p<0.05). CONCLUSIONS:Raised inflammatory markers are associated with pulmonary, cutaneous and musculoskeletal manifestations of SSc. Rising inflammatory markers are correlated with declining respiratory function tests. This suggests inflammatory markers have a role in the assessment of SSc disease activity.

Background Although immunological blockade of checkpoint inhibitors (CIs) for cancer therapy is known to be associated with exacerbated inflammation recapitulating many features of autoimmunity1, including synovitis resembling rheumatoid arthritis (RA)2, no reports have investigated cellular infiltrates in synovial tissue (ST) of these patients. Here we provide the first report on ST cell infiltration, in particular PD1 expressing T cells, after a PD1 inhibitor-induced (Nivolumab) immune related adverse event (irAE) and severe synovitis. Objectives To characterise ST cellular infiltration in PD1 inhibitor induced arthritis with particular reference to PD1 positive T cells and compare these changes with active early RA ST. Methods Arthroscopic ST biopsies, parallel synovial fluid (SF) and PBMCs were collected from a DMARD-naïve nivolumab-treated small cell lung cancer (SCLC) patient with severe peripheral inflammatory polyarthritis (negative RF and ACPA; no axial or extra-articular irAE); 3 DMARD-naïve patients with seropositive early RA (<12 months duration; fulfilling 2010 ACR/EULAR criteria) were used as comparators. Serial sections from fresh-frozen ST blocks were stained with H and E, CD3, CD45RO, CD55 and CD68 and semi-quantitatively scored as described3. ST, SF and PBMC cell suspensions were stained with Zombie UV (BioLegend), CD45RO, PD1, CD3, ICOS, CD8, CD4, CD20 (all BD) prior to flow cytometry. Cells were gated on live, singlet, lymphocytes, CD3+ and CD4+ T cells, and CD20+ and CD8+ T cells were excluded from endpoint PD1+, ICOS+ and CD45RO+analysis. Results CD68 +macrophage, CD20+ B cell and CD3+ T cell and CD45RO+memory T cell infiltration in IC-irAE was comparable to RA ST on semi-quantitative scoring, while TNF; staining was markedly elevated in CI-irAE compared to RA (CI-irAE-TNF; 4, RA-TNF; 2). Flow cytometry identified a striking absence of PD1+ ICOS+ CD4+T cells in IC-irAE SCLC in all compartments (CI-irAE: ST; 0.06, SF; 0.01, PBMCs; 0.00) compared to RA (RA: ST mean and SEM; 22.13±3.63: SF; 45.95±1.85: and to a lesser extent in PBMCs; 0.41±0.13: n=3 for each), despite comparable CD4 +T cell frequency in each compartment (frequency of CD3 +cells, CI-irAE: ST; 57.8, SF; 64.7, PBMCs; 38.2, RA: ST; 45.9±15.3, SF; 49.5±11.2, PBMCs; 62.2±13.8, figure 1). Figure 1 PD-1 +ICOS + T cells are absent in CI-irAE. Showing the PD-1 +ICOS + frequency of CD4 +T cells gated on live, singlet, lymphocytes, and CD3+, CD20- and CD8-cells. (RA: ST mean and SEM; 22. 13±3.63: SF; 45.95±1.85 n=3 for each, CI-irAE: ST; 0.06, SF; 0.01, PBMCs; 0.00, n=1 for each). Conclusions While ST infiltration in CI-irAE SCLC recapitulates many features of RA histopathology, PD1 expression principally distinguishes RA from irAE ST T-cell infiltration. Despite abundant CD4 and CD45RO memory T cell infiltration in CI-irAE comparable with RA, we found a conspicuous absence of PD1 positive T-cells. Further research is needed to fully understand the nature of reduced PD1 expression in this setting and the source of elevated TNF, which could shed light on the pathogenesis of CI-irAE and guide CI-irAE management. References [1] van der Vlist, et al. Immune checkpoints and rheumatic diseases: what can cancer immunotherapy teach us?Nat Rev Rheumatol2016. [2] Naidoo, J. et al. Inflammatory Arthritis: A Newly Recognized Adverse Event of Immune Checkpoint Blockade. Oncologist2017. [3] Tak, P. P. et al. Analysis of the synovial cell infiltrate in early rheumatoid synovial tissue in relation to local disease activity. Arthritis Rheum. 1997. Disclosure of Interest None declared

Autoantibodies directed against the Ku autoantigen are present in systemic sclerosis (SSc) and have been associated with myositis overlap and interstitial lung disease (ILD). However, there is a paucity of data on the clinical correlates of anti-Ku antibodies in the absence of other SSc-specific antibodies. The aim of this study was to assess the clinical correlates of single-specificity anti-Ku in SSc.An international (Canada, Australia, USA, Mexico) cohort of 2140 SSc subjects was formed, demographic and clinical variables were harmonized, and sera were tested for anti-Ku using a line immunoassay. Associations between single-specificity anti-Ku antibodies (i.e., in isolation of other SSc-specific antibodies) and outcomes of interest, including myositis, ILD, and survival, were investigated.Twenty-four (1.1%) subjects had antibodies against Ku, and 13 (0.6%) had single-specificity anti-Ku antibodies. Subjects with single-specificity anti-Ku antibodies were more likely to have ILD (58% vs 34%), and to have increased creatine kinase levels (>3× normal) at baseline (11% vs 1%) and during follow-up (10% vs 2%). No difference in survival was noted in subjects with and without single-specificity anti-Ku antibodies.This is the largest cohort to date focusing on the prevalence and disease characteristics of single-specificity anti-Ku antibodies in subjects with SSc. These results need to be interpreted with caution in light of the small sample. International collaboration is key to understanding the clinical correlates of uncommon serological profiles in SSc.

OBJECTIVES To determine the prevalence and correlates of antiphospholipid antibodies (APLA) in systemic sclerosis (SSc). METHODS Nine hundred and forty SSc patients were tested for APLA using an ELISA assay at recruitment. Clinical manifestations were defined as present, if ever present from SSc diagnosis. Logistic regression analysis was used to determine the associations of APLA. RESULTS One or more types of APLA were present in 226 (24.0%) patients. Anticardiolipin (ACA) IgG (ACA-IgG) antibodies were associated with right heart catheter-diagnosed pulmonary arterial hypertension (PAH), with higher titres corresponding with a higher likelihood of PAH (moderate titre (20-39 U/ml) ACA-IgG odds ratio [OR] 1.70, 95% CI: 1.01-2.93, p=0.047; high titre (>40 U/ml) ACA-IgG OR 4.60, 95% CI:1.02-20.8, p=0.047). Both ACA-IgM (OR 2.04, 95% CI: 1.4-3.0, p<0.0001) and ACA-IgG (OR 1.84, 95% CI: 1.2-2.8, p=0.005) were associated with interstitial lung disease (ILD). Increasing ACA-IgM and IgG titres were associated with increased likelihood of ILD. ACA-IgG was a marker of coexistent pulmonary hypertension and ILD (ILD-PH) (OR 2.10, 95% CI: 1.1-4.2, p=0.036). We also found an association between ACA-IgG and digital ulcers (OR 1.76, 95% CI: 1.16-2.67, p=0.008) and ACA-IgM and Raynaud's phenomenon (OR 2.39, 95% CI: 1.08-5.27, p=0.031). There was no association between APLA and SSc disease subtype, peak skin score, presence of other autoantibodies, mortality or other disease manifestations. CONCLUSIONS The association of APLA with PAH, ILD, ILD-PH, Raynaud's phenomenon and digital ulcers suggests that endothelial abnormalities and small vessel thrombosis may be important in the pathogenesis of these disease features.