Objectives Plasmacytoid dendritic cells (pDC) have been implicated in the pathogenesis of autoimmune diseases, such as scleroderma (SSc). However, this has been derived from indirect evidence using ex vivo human samples or mouse pDC in vivo. We have developed human-specific pDC models to directly identify their role in inflammation and fibrosis, as well as attenuation of pDC function with BDCA2-targeting to determine its therapeutic application. Methods RNAseq of human pDC with TLR9 agonist ODN2216 and humanised monoclonal BDCA2 antibody, CBS004. Organotypic skin rafts consisting of fibroblasts and keratinocytes were stimulated with supernatant from TLR9-stimulated pDC and with CBS004. Human pDC were xenotransplanted into Nonobese diabetic/severe combined immunodeficiency (NOD SCID) mice treated with Aldara (inflammatory model), or bleomycin (fibrotic model) with CBS004 or human IgG control. Skin punch biopsies were used to assess gene and protein expression. Results RNAseq shows TLR9-induced activation of human pDC goes beyond type I interferon (IFN) secretion, which is functionally inactivated by BDCA2-targeting. Consistent with these findings, we show that BDCA2-targeting of pDC can completely suppress in vitro skin IFN-induced response. Most importantly, xenotransplantation of human pDC significantly increased in vivo skin IFN-induced response to TLR agonist and strongly enhanced fibrotic and immune response to bleomycin compared with controls. In these contexts, BDCA2-targeting suppressed human pDC-specific pathological responses. Conclusions Our data indicate that human pDC play a key role in inflammation and immune-driven skin fibrosis, which can be effectively blocked by BDCA2-targeting, providing direct evidence supporting the development of attenuation of pDC function as a therapeutic application for SSc.

Many urothelial carcinomas (UC) contain activating PIK3CA mutations. In telomerase-immortalized normal urothelial cells (TERT-NHUC), ectopic expression of mutant PIK3CA induces PI3K pathway activation, cell proliferation and cell migration. However, it is not clear whether advanced UC tumors are PIK3CA-dependent and whether PI3K pathway inhibition is a good therapeutic option in such cases. We used retrovirus-mediated delivery of shRNA to knock down mutant PIK3CA in UC cell lines and assessed effects on pathway activation, cell proliferation, migration and tumorigenicity. The effect of the class I PI3K inhibitor GDC-0941 was assessed in a panel of UC cell lines with a range of known molecular alterations in the PI3K pathway. Specific knockdown of PIK3CA inhibited proliferation, migration, anchorage-independent growth and in vivo tumor growth of cells with PIK3CA mutations. Sensitivity to GDC-0941 was dependent on hotspot PIK3CA mutation status. Cells with rare PIK3CA mutations and co-occurring TSC1 or PTEN mutations were less sensitive. Furthermore, downstream PI3K pathway alterations in TSC1 or PTEN or co-occurring AKT1 and RAS gene mutations were associated with GDC-0941 resistance. Mutant PIK3CA is a potent oncogenic driver in many UC cell lines and may represent a valuable therapeutic target in advanced bladder cancer.

Skeletal muscle damage is a common clinical manifestation of systemic sclerosis (SSc). C-X-C chemokine ligand 10 (CXCL10) is involved in myopathy and cardiomyopathy development and is associated with a more severe SSc prognosis. Interestingly, the phosphodiesterase type 5 inhibitor (PDE5i) sildenafil reduces CXCL10 sera levels of patients with diabetic cardiomyopathy and in cardiomyocytes. Here, we analyzed the levels of CXCL10 in the sera of 116 SSc vs. 35 healthy subjects and explored differences in 17 SSc patients on stable treatment with sildenafil. CXCL10 sera levels were three-fold higher in SSc vs. healthy controls, independent of subset and antibody positivity. Sildenafil treatment was associated with lower CXCL10 sera levels. Serum CXCL10 strongly correlated with the clinical severity of muscle involvement and with creatine kinase (CK) serum concentration, suggesting a potential involvement in muscle damage in SSc. In vitro, sildenafil dose-dependently reduced CXCL10 release by activated myocytes and impaired cytokine-induced Signal transducer and activator of transcription 1 (STAT1), Nuclear factor-κB (NFκB) and c-Jun N-terminal kinase (JNK) phosphorylation. This was also seen in cardiomyocytes. Sildenafil-induced CXCL10 inhibition at the systemic and human muscle cell level supports the hypothesis that PDE5i could be a potential therapeutic therapy to prevent and treat muscle damage in SSc.

Objective: To assess the value of serum type I interferon (IFN) score in predicting clinically meaningful progression in limited cutaneous systemic sclerosis (lcSSc) using a novel composite endpoint adopted from the MINIMISE clinical trial. Methods: A retrospective, longitudinal lcSSc cohort was identified within a national, multicenter observational cohort. The MINIMISE trial combined Morbi‐mortality endpoint was used as the clinical outcome for a time to clinical worsening (TTCW) design. The IFN score was calculated from the serum concentration of chemokine C‐C motif ligand (CCL) 2, CCL8, CCL19, C‐X‐C motif chemokine ligand (CXCL) 9, CXCL10, and CXCL11 on patients and age‐ and sex‐matched healthy controls (HCs). A “high” IFN score was defined as 2 SDs above the HC mean. The association of the IFN score with TTCW was assessed using Cox proportional hazard regressions and Kaplan‐Meier curves. The potential improvement in risk stratification when combining IFN score with lcSSc clinical features was explored. Results: A total of 149 patients were included in the analysis: 67 “high” IFN and 82 “low.” High IFN patients presented a shorter TTCW (74.7 months [95% confidence interval (CI) 70.1–79.3] vs 110.6 months [95% CI 107.2–114.0]; P < 0.001) and met the endpoint in higher proportion compared with low IFN (55% vs 12%; P < 0.001). A high IFN score conferred hazard ratio (HR) 5.5 (95% CI 2.7–11.3) for TTCW compared with low IFN, and IFN score as a continuous variable conferred HR 2.38 (95% CI 1.4–4.0) for TTCW independently of clinical variables. Pulmonary arterial hypertension, interstitial lung disease, digital ulcers, and modified Rodnan skin score were associated with TTCW. An exploratory analysis showed that these clinical features improve risk stratification over time in combination with IFN score. Conclusion: Serum assessment of type I IFN activity is a valuable predictor of clinically meaningful outcomes in lcSSc. The combination of serum IFN score with sentinel clinical features can improve stratification strategies in clinical trials and patient management. image

Secreted Frizzled Receptor Protein 4 (SFRP4) has been shown to be increased in Scleroderma (SSc). To determine its role in immune-driven fibrosis, we analysed SSc and sclerotic Chronic Graft Versus Host Disease (sclGVHD) biosamples; skin biopsies (n = 24) from chronic GVHD patients (8 with and 5 without sclGVHD), 8 from SSc and 3 healthy controls (HC) were analysed by immunofluorescence (IF) and SSc patient sera (n = 77) assessed by ELISA. Epithelial cell lines used for in vitro Epithelial-Mesenchymal-Transition (EMT) assays and analysed by Western Blot, RT-PCR and immunofluorescence. SclGVHD skin biopsies resembled pathologic features of SSc. IF of fibrotic skin biopsies indicated the major source of SFRP4 expression were dermal fibroblasts, melanocytes and vimentin positive/caveolin-1 negative cells in the basal layer of the epidermis. In vitro studies showed increased vimentin and SFRP4 expression accompanied with decreased caveolin-1 expression during TGFβ-induced EMT. Additionally, SFRP4 serum concentration correlated with severity of lung and skin fibrosis in SSc. In conclusion, SFRP4 expression is increased during skin fibrosis in two different immune-driven conditions, and during an in vitro EMT model. Its serum levels correlate with skin and lung fibrosis in SSc and may function as biomarker of EMT. Further studies are warranted to elucidate the role of SFRP4 in EMT within the pathogenesis of tissue fibrosis.

Objective: The Very Early Diagnosis of Systemic Sclerosis (VEDOSS) EUSTAR study showed that, despite not showing any clinical sign of disease, patients with Raynaud’s and ANA and/or capillaroscopy abnormalities often progress to SSc within 5 years. We aimed to determine whether VEDOSS biosamples show biological SSc activity pre-clinically. Methods: Skin biopsies were histologically analysed. Dermal fibroblasts analysed by RT-qPCR and gel contraction assays. Sera were assayed by Luminex (CXCL10) or ELISA (ELF score). Healthy controls (HC) and SSc biosamples were used for controls. Results: Overall, 114 consecutive VEDOSS patients were enrolled, of which 36 consented to have skin biopsies. Skin biopsies showed a variable but overall increased collagen staining and skin thickness, increased perivascular infiltrate of CD45-positive cells and CXCL10 expression. In vitro, VEDOSS dermal fibroblasts showed increased profibrotic gene expression and contractibility compared with HC. Increased serological CXCL10 [mean (s.d.) 75.90 (107.80) vs HC 39.90 (26.27) pg/ml, P = 0.02] and ELF score was evident in VEDOSS compared with HC [8.19 (0.78) vs 8.55 (0.79), P = 0.04]. In longitudinal analysis of a median of 27.5 (interquartile range 44.5) months, 14.9% of VEDOSS patients progressed to SSc. Baseline CXCL10 serum concentration was significantly higher in the VEDOSS patients that progressed (2-fold increase, P = 0.0071) and correlated with ELF score (R = 0.3096, P = 0.0065). Conclusions: Despite not fulfilling classification criteria, VEDOSS patients show SSc-linked fibrosis and immunity dysregulation both within the tissue and sera, supporting a biological diagnosis of disease and a window of opportunity to detect the biological pathways amenable for preventive intervention.