ScRNA-seq and Proteomics Uncover Glycolytic Dysregulation Linking Skin and Systemic Inflammation in Dermatomyositis.

Dermatomyositis (DM) is a rare yet devastating autoimmune disease characterized by inflammatory and vasculopathic changes in skin and muscle. DM and systemic lupus erythematosus (lupus) skin lesions have overlapping clinical and histopathological features, yet disparate responses to available therapeutics. DM skin disease is often relapsing and recalcitrant. To investigate DM immunopathogenesis, non-lesional skin, lesional skin, and circulating immune cells from DM patients were analyzed using single-cell RNA-sequencing. Samples were analyzed in parallel with lesional and non-lesional lupus skin, healthy control skin, and peripheral blood. We demonstrate a pervasive type I interferon (IFN) signature in DM stroma that persists in culture and is distinguished from lupus by upregulation of VEGF and IL-18 signaling in DM keratinocytes. Furthermore, endothelial cells (ECs) in lesional DM exhibit decreased proliferation that was not observed in lupus. Using cell communication networks, we identified a population of DM-specific monocytes interacting with non-proliferating DM ECs. Co-culture of monocytes from DM patients with ECs resulted in increased EC apoptosis inhibited by JAK1 blockade. JAK1 inhibition also resulted in reversal of DM-stromal and inflammatory signatures. Together, our data provide a comprehensive cross-disease characterization of lesional and non-lesional skin of DM compared to lupus and implicate monocyte-mediated EC dysfunction in DM vasculopathy and support JAK inhibition for refractory skin disease.

Interleukin (IL)-31 is implicated in pruritus associated with pruritic skin diseases like atopic dermatitis. Although pruritus is a prominent feature in dermatomyositis (DM), few studies have evaluated the pathogenesis of DM-associated itch. To establish the prevalence of itch in DM, and to investigate the role of IL-31 in DM-related itch. Pruritus and disease activity of DM were evaluated by a visual analogue scale (VAS) and the Cutaneous Disease and Activity Severity Index (CDASI), respectively. Expression of IL-31 and IL-31 receptor alpha (IL-31RA) in lesional DM, nonlesional DM and healthy control skin was evaluated by quantitative reverse-transcriptase polymerase chain reaction and immunofluorescence. Flow cytometry was performed on skin cells isolated from lesional DM skin to identify cellular sources of IL-31 in DM. Among 191 patients with DM, 50·8% had moderate-to-severe itch, and itch was correlated with increased cutaneous severity (r = 0·34). In patients with itchy DM, gene expression of IL31 and IL31RA in lesional skin was upregulated compared with nonlesional skin and healthy control skin. IL31 mRNA expression positively correlated with VAS itch score (r = 0·67). On immunofluorescence, immunoreactivity for IL-31 and IL-31RA was stronger in lesional skin. Flow cytometry showed that lesional DM skin contained significantly more IL-31-producing cells, and CD4+ cells were the most common cell type. Lenabasum, an emerging treatment for DM, significantly downregulated IL-31 from CpG-stimulated peripheral blood mononuclear cells. Increased skin IL-31 may play a role in DM-associated itch, and ongoing trials will evaluate the effects of systemic treatment on IL-31 and itch in DM.

Dermatomyositis (DM) and systemic lupus erythematosus (SLE) have common skin features, including dermal mucin deposition and interferon signature, although their roles are unknown. To identify common or specific molecular changes in DM and SLE skin. Proteomic analysis was performed using DM and healthy skin. Glycosaminoglycans were analysed by high-performance liquid chromatography. The expression of 60 proteins was upregulated or downregulated in DM skin compared with healthy skin in the proteomic analysis. Among those proteins, PSMB9, an immunoproteasome subunit, was upregulated in the epidermis of DM and SLE, but not in other skin diseases. Furthermore, versican V1, a core protein for glycosaminoglycans, was upregulated, while type I collagen was downregulated in the dermis of DM and SLE skin. Interferon stimulated PSMB9 expression in cultured keratinocytes and reduced collagen expression in dermal fibroblasts, but did not affect versican expression. The PSMB9 knock-down in keratinocytes led to significant suppression of transforming growth factor (TGF)-β2 and TGF-β3, inducers of versican synthesis. TGF-β3 expression was upregulated in both DM and SLE, while TGF-β2 expression was increased only in the DM epidermis. ΔDiHS-diS1, a component of heparan sulfate, was significantly increased only in DM. TGF-β2 expression significantly increased the ΔDiHS-diS1 expression in dermal fibroblasts invitro. The interferon signature in DM and SLE skin reduces collagen in dermal fibroblasts, whereas overexpression of PSMB9 induced by interferon stimulates versican inducers in epidermal keratinocytes. In addition, the TGF-β2-ΔDiHS-diS1 pathway may be responsible for the specific molecular change in DM skin.

Dermatomyositis (DM) is a systemic autoimmune disease characterized by chronic inflammation in proximal skeletal muscles, skin and other target organs. Many physicians focus on the weakness and the resulting physical dysfunction as the most disabling features of DM and therapeutic trials often have been directed at improving these manifestations. Subsequently, the skin disease is often neglected by treating physicians as a less severe manifestation of illness and is often not the focus of therapy. Nonetheless, despite the second-hand status often afforded the skin disease of DM, it can be as debilitating as the muscle disease. Patients with adult and juvenile DM often experience a variety of both sun-exposed and non-sun-exposed skin rashes, including erythematous and vasculopathic lesions (1;2). Pruritus is a frequent manifestation of active DM skin disease that adversely impacts quality of life (3). Incompletely treated cutaneous manifestations can lead to dystrophic calcification in the skin and subcutaneous tissues in up to 25% of juvenile-onset DM patients and 15% of adults with DM (4). Skin atrophy, dyspigmentation and lipodystrophy, the loss of subcutaneous tissue resulting in metabolic sequelae of insulin resistance and hyperlipidemia, are common outcomes of prior inflammation in the skin and subcutaneous tissue (4;5). Discordance in the presentation of skin and muscle symptoms and their different impact on outcomes are becoming evident. The characteristic DM skin rashes of Gottron’s papules and the heliotrope rash predate the onset of muscle symptoms in almost half of the patients (6). Periungual nailfold capillary changes, an almost universal feature of DM, correlate more with skin than muscle disease activity (7). Persistence of Gottrons papules, other skin rashes, and periungual nailfold capillary changes are associated with a longer time to remission in patients with juvenile DM and a monocyclic illness course (7;8). Thus, we can no longer neglect the skin as an important manifestation of DM, as skin disease significantly impacts the outcome of this illness and clearly deserves its own focus for therapy. The pathologic changes in the affected skin, including perivascular inflammation at the dermal-epidermal junction and resulting small vessel vasculopathy and capillary loss, appear to parallel similar changes present in the affected muscles (9). Corresponding information on the pathogenesis of the skin disease and a fuller elucidation of the role of plasmacytoid dendritic cells and the type I interferon response in the affected skin, however, has been lagging. In this issue of Arthritis and Rheumatism, Shrestha and colleagues (10) describe several novel findings related to the pathogenesis of the skin disease of patients with juvenile DM, and extend observations on the type I interferon pathway, in a carefully conducted study that not only controls for disease state and treatment, but also pairs skin and muscle tissue in simultaneous examinations. These authors also confirm that mature dendritic cells (DC-LAMP positive), which are plasmacytoid in origin (BDAC2 positive), are increased in the affected muscle of newly-diagnosed, untreated patients with juvenile DM compared to control children. These cells are primarily found in perivascular and perifascicular areas, which are the regions of greatest pathologic change (11;12). The majority of juvenile DM muscles also express increased MxA protein, a product of type I interferon signaling, in perifascicular myofibers and in the perivascular inflammatory infiltrates. In skin biopsies, taken from an overlying muscle biopsy site and not always involving an active rash, mature dendritic cells, which are apparently of plasmacytoid origin and express the MxA protein, are present throughout the epidermis and dermis, as well as at the periphery of blood vessels. The frequency of these cells and the intensity of staining are higher in the skin of juvenile DM patients than that of the control subjects. Also the expression of all dendritic cell markers and the type I interferon-induced MxA protein is stronger in the skin than muscle tissue. These authors also report that the number of mast cells is increased throughout the dermis of patients with juvenile DM compared to controls without an inflammatory condition, that these cells appear to be degranulated and thus activated, and that their frequency is similar in both lesional and non-lesional DM skin. There is no difference in the numbers of mast cells, however, in the affected muscle tissues of juvenile DM patients compared to muscle tissues from control subjects. Their findings point to several novel pathways in the pathogenesis of DM skin disease and, while suggesting certain similarities between the skin and muscle disease, they also show us certain distinctions in the pathogenesis of DM skin and muscle disease.

BackgroundLenabasum is a cannabinoid type 2 receptor (CB2R) reverse agonist that demonstrates anti-inflammatory effects in vivo and in vitro in dermatomyositis (DM) and is currently being investigated for therapeutic potential. The purpose of our study is to investigate CB2R distribution as well as the effects of lenabasum in DM.MethodsImmunohistochemistry staining (IHC) was utilized to examine immune cell and cytokine production changes in lesional DM skin biopsies from lenabasum and placebo-treated patients. CB2R expression in various immune cell populations within DM skin was investigated with image mass cytometry (IMC), whereas flow cytometry elucidated CB2R expression in DM peripheral blood mononuclear cells (PBMCs) as well as cytokine production by CB2R-expressing cell populations.ResultsAfter 12 weeks of lenabasum treatment, IHC staining showed that CD4+ T cells, CB2R, IL-31, IFN-γ, and IFN-β cytokines were downregulated. IFN-γ and IFN-β mRNA decreased in lesional DM skin but not in PBMCs. IMC findings revealed that CB2R was upregulated in DM lesional skin compared to HC skin and DM PBMCs (p<0.05). In DM skin, CB2R was upregulated on dendritic cells, B cells, T cells, and macrophages while dendritic cells had the greatest expression in both DM skin and PBMCs (p<0.05). These CB2R+ cells in the skin produce IL-31, IL-4, IFN-γ, and IFN-β.ConclusionOur findings of differential CB2R expression based on location and cell type suggest modes by which lenabasum may exert anti-inflammatory effects in DM and highlights dendritic cells as potential therapeutic targets.

BackgroundDermatomyositis (DM) is an autoimmune disease that mainly affects the skin, muscle, and lung. The pathogenesis of skin inflammation in DM is not well understood.Methodology and FindingsWe analyzed genome-wide expression data in DM skin and compared them to those from healthy controls. We observed a robust upregulation of interferon (IFN)-inducible genes in DM skin, as well as several other gene modules pertaining to inflammation, complement activation, and epidermal activation and differentiation. The interferon (IFN)-inducible genes within the DM signature were present not only in DM and lupus, but also cutaneous herpes simplex-2 infection and to a lesser degree, psoriasis. This IFN signature was absent or weakly present in atopic dermatitis, allergic contact dermatitis, acne vulgaris, systemic sclerosis, and localized scleroderma/morphea. We observed that the IFN signature in DM skin appears to be more closely related to type I than type II IFN based on in vitro IFN stimulation expression signatures. However, quantitation of IFN mRNAs in DM skin shows that the majority of known type I IFNs, as well as IFN g, are overexpressed in DM skin. In addition, both IFN-beta and IFN-gamma (but not other type I IFN) transcript levels were highly correlated with the degree of the in vivo IFN transcriptional response in DM skin.Conclusions and SignificanceAs in the blood and muscle, DM skin is characterized by an overwhelming presence of an IFN signature, although it is difficult to conclusively define this response as type I or type II. Understanding the significance of the IFN signature in this wide array of inflammatory diseases will be furthered by identification of the nature of the cells that both produce and respond to IFN, as well as which IFN subtype is biologically active in each diseased tissue.

There has been increased interest recently in the concept of dermatomyositis (DM) skin disease occurring for unusually long periods (<6 months) without the development of muscle weakness (i.e., amyopathic DM [syn. DM sine myositis]). This interest has been heightened by the realization that adult-onset clinically amyopathic DM (CADM) and classic DM patients might have similar levels of risk for systemic complications such as interstitial lung disease and internal malignancy. Contrastingly, in juvenile-onset CADM, patients might have a significantly lower risk of the complications of severe calcinosis and cutaneous vasculitis compared with those with juvenile-onset classical DM. This chapter will provide an overview of the diagnostic criteria for CADM, a comparison of the clinical and laboratory features of CADM and classical DM, and a discussion of management issues of DM skin disease including topical and systemic therapy.

A limited number of case series has indicated that methotrexate (MTX) might be a useful drug in the treatment of dermatomyositis (DM), a rare autoimmune disease involving the skin and muscles. However, these earlier studies mainly focused on the efficacy of MTX on DM muscular symptoms. To analyse the efficacy of MTX on skin lesions in DM, the records of 34 patients with DM seen between 2004 and 2009 were retrospectively analysed, and the DM skin disease activity at different time points was determined, with specific focus on cutaneous features using the validated Cutaneous Dermatomyositis Activity Index (CDASI) score. The lesional inflammation was scored in primary skin biopsies. Additionally, we performed a systematic review of the available literature. In our series, 11 patients with DM received MTX, and in 8 of them, MTX led to a significant reduction of the DM skin lesions. CDASI scores decreased from 15.7 to 6.4 (P < 0.01) within 2-3 months, supporting the effectiveness of MTX in skin disease in DM. The lymphocytic infiltrate in primary skin lesions of MTX responders was significantly more pronounced than that in nonresponders. These results indicate that MTX might be an effective drug to treat the cutaneous symptoms of DM, as measured by the validated CDASI. Interestingly, MTX responders histologically presented a significantly stronger lesional lymphocytic inflammatory infiltrate than did nonresponders. These findings suggest that the functional inhibition of lymphocyte migration in the skin might be an important mechanism of MTX in the treatment of DM.

Pruritus is a common excruciating symptom in systemic autoimmune diseases such as dermatomyositis (DM) but the pathogenesis is not fully understood. We intended to investigate the targeted expression analysis of candidate molecules involved in the development of pruritus in lesional vs. non-lesional skin samples of patients affected with active DM. We looked for correlations between the investigated pruriceptive signaling molecules, disease activity, and itching sensation of DM patients. Interleukins (IL-33 and IL-6), tumor necrosis factor α (TNF-α), peroxisome proliferator-activated receptor γ (PPAR-γ), and ion channels belonging to the transient receptor potential (TRP) family were analyzed. The expression of TNF-α, PPAR-γ, IL-33, IL-6, and TRP channels in lesional DM skin was evaluated by RT-qPCR and immunohistochemistry and was compared with non-lesional DM skin samples. Pruritus, disease activity, and damage of DM were evaluated by the 5-D itch scale and Cutaneous Dermatomyositis Disease Area and Severity Index (CDASI), respectively. Statistical analysis was performed with IBM SPSS 28 software. A total of 17 active DM patients participated in the study. We could show that the itching score was positively correlated with the CDASI activity score (Kendall's tau-b = 0.571; p = 0.003). TNF-α gene expression was significantly higher in lesional DM skin than in non-lesional DM skin (p = 0.009) and differed in the subgroups of patients with different itch intensities (p = 0.038). The mRNA expression of lesional IL-6 correlated positively with 5-D itch and CDASI activity score (Kendall's tau-b = 0.585; p = 0.008 and 0.45; p = 0.013, respectively). TRPV4 expressions were positively correlated with CDASI damage score (Kendall's tau-b = 0.626; p < 0.001), but the mRNA expressions of the TRP family, PPAR-γ, IL-6, and IL-33 were not different in lesional and non-lesional samples. Immunohistochemistry analysis did not find significant alterations in the expressions of TNF-α, PPAR-γ, IL-6, and IL-33 in lesional and non-lesional regions. Our results argue that cutaneous disease activity, TNF-α, and IL-6 might play a central role in DM-associated itch, while TRPV4 plays a central role in tissue regeneration.

021 CXCL13-producing peripheral T helper cells as potential mediators of photosensitivity in dermatomyositis

Background/Aims Anti-synthetase syndrome (ASS) represents a distinct entity within myositis spectrum disorders; however, correct classification of patients with anti-tRNA synthetase autoantibodies and skin manifestations akin to dermatomyositis (DM) remains uncertain. Our aim was to compare clinical characteristics, skin involvement, and malignancy, between patients with ASS and DM, classified by disease-specific autoantibodies. Methods Data from 05/2009-03/2016 from 9 countries from the prospective, myositis EuroMyositis registry were downloaded. Those with anti-tRNA synthetase autoantibodies (Jo-1/PL-7/PL-12/OJ/EJ/KS) were classified as ASS, and those with Mi-2/TIF1-γ/NXP2/SAE/MDA5 autoantibodies as DM. Clinical phenotypes including malignancies (except skin malignancies) were tabulated. Characteristics of patients with skin involvement (excluding mechanic’s hands and Raynaud’s phenomenon) were compared using Fisher’s exact test with Bonferroni corrected p-values. Results Of 3,067 patients, 2,028 had autoantibody profiling results (66.1%), of which 783 (38.6%) were positive for at least one of the autoantibodies being considered. Five patients with dual autoantibody specificities were excluded. Of the remaining 778, 320 (41.1%) were classified as DM, and 458 (58.9%) as ASS. Median age at diagnosis was 48.2 years (interquartile range [IQR] 37.5 to 57.8) in the DM cohort and 49 (IQR 38.3 to 62.2) in the ASS cohort. Skin involvement was present in 277 (86.6%) DM patients (DM skin) vs 204 (44.5%) ASS patients (ASS skin) (pcorr&amp;lt;0.01) (Table 1). Whilst relatively high proportions of so-called “DM-specific” rashes were seen in ASS skin, the frequency of heliotrope rash, Gottron’s papules, violaceous rash, periorbital rash, V-sign, shawl sign, and periungual erythema was significantly higher in DM skin (pcorr&amp;lt;0.01 for all). Conversely, mechanic’s hands, Raynaud’s, arthritis, and interstitial lung disease were more frequent in ASS skin (pcorr&amp;lt;0.01 for all). Malignancy was less frequent in ASS skin vs DM skin (pcorr&amp;lt;0.01) and occurred temporally closer to myositis diagnosis in DM skin (median 0.95 months [IQR -6.54. to 19.45]) vs ASS skin (median 12.17 months [IQR -15.85 to 79.31]). Conclusion Patients with ASS have frequent skin involvement but also a distinct clinical phenotype compared to DM. These findings may inform the development of future classification criteria for ASS. Disclosure R.M. Hum: None. J.B. Lilleker: None. J.A. Lamb: None. W.E. Ollier: None. G. Wang: None. L.R. Wedderburn: None. L.P. Diederichsen: None. J. Schmidt: None. P. Oakley: None. O. Benveniste: None. M.G. Danieli: None. K. Danko: None. N.T.P. Thuy: None. M.V.D. Mercado: None. H. Andersson: None. B.D. Paepe: None. J.L.D. Bleecker: None. B. Maurer: None. L.J. McCann: None. N. Pipitone: None. N. McHugh: None. P. New: None. J. Vencovsky: None. I.E. Lundberg: None. H. Chinoy: None.

There has been increased interest recently in the concept of dermatomyositis (DM) skin disease occurring for unusually long periods (<6 months) without the development of muscle weakness (i.e., amyopathic DM (syn. DM sine myositis)). This interest has been heightened by the realization that adult-onset clinically amyopathic DM (CADM) and classic DM patients might have similar levels of risk for systemic complications such as interstitial lung disease and internal malignancy. Contrastingly, in juvenile-onset CADM, patients might have a significantly lower risk of the complications of severe calcinosis and cutaneous vasculitis compared with those with juvenile-onset classical DM. This chapter will provide an overview of the diagnostic criteria for CADM, a comparison of the clinical and laboratory features of CADM and classical DM, and a discussion of management issues of DM skin disease including topical and systemic therapy.

BackgroundCutaneous lupus erythematosus (CLE) and dermatomyositis (DM) are autoimmune diseases with characteristic cutaneous rashes. Both are histopathologically characterized by interface dermatitis and they are difficult and sometimes impossible to differentiate...

BackgroundCutaneous lupus erythematosus (CLE) and dermatomyositis (DM) are autoimmune diseases with characteristic cutaneous rashes. Both are histopathologically characterized by interface dermatitis and they are difficult and sometimes impossible to differentiate...

Dermatomyositis (DM) is an autoimmune disease of unknown origin affecting skin and muscles. Infiltrating autoreactive T lymphocytes are thought to play an important pathogenetic role, but it is unclear which mechanisms are involved in the recruitment of these cells. Recent studies provided evidence that a type I interferon (IFN)-driven immune response, including the recruitment of T cells via IP10/CXCR3 interactions, might be important for the generation of skin lesions of cutaneous lupus erythematosus (CLE), an autoimmune disease that shares some clinical and histopathological features with DM. We hypothesized that a similar mechanism might also be involved in the pathogenesis of DM skin lesions. Skin biopsies of 23 donors (11 DM, 5 healthy controls, 7 CLE controls) were analysed by immunohistochemistry using monoclonal antibodies against CD3, CD4, CD8, CD20, CD68, CD123, the chemokine receptor CXCR3 and its ligand IP10/CXCL10, and the myxovirus-resistance protein A (MxA)-protein, which is a specific marker for type I IFNs. We detected strong expression of the MxA protein in all DM skin biopsies, indicating involvement of type I IFNs. Expression of MxA was closely associated with expression of the interferon-inducible protein IP10/CXCL10 and the recruitment of CXCR3+ lymphocytes. Plasmacytoid dendritic cells appear to be an important source of type I IFNs in DM. Our results support the hypothesis that lesional type I IFN signalling, induction of IP10 expression, and recruitment of potentially autoreactive T cells via IP10/CXCR3 interaction are involved in the pathogenesis of DM skin lesions.