Type-2 immunity associated with type-1 related skin inflammatory diseases: friend or foe?

Chronic inflammatory skin diseases are multifactorial diseases that combine genetic predisposition, environmental triggers, and metabolic disturbances associated with abnormal immune responses. From an immunological perspective, the better understanding of their physiopathology has demonstrated a large complex network of immune cell subsets and related cytokines that interact with both epidermal and dermal cells. For example, in type-1-associated diseases such as alopecia areata, vitiligo, and localized scleroderma, recent evidence suggests the presence of a type-2 inflammation that is well known in atopic dermatitis. Whether this type-2 immune response has a protective or detrimental impact on the development and chronicity of these diseases remains to be fully elucidated, highlighting the need to better understand its involvement for the management of patients. This mini-review explores recent insights regarding the potential role of type-2-related immunity in alopecia areata, vitiligo, and localized scleroderma.

International exchange on the clinical practice and research of rheumatic skin diseases: A report of the 5th International Conference of Cutaneous Lupus Erythematosus.

The 5th International Conference of Cutaneous Lupus Erythematosus was held in Tokyo, Japan on May 9 and 10, 2023. The latest topics on the pathogenesis, diagnosis, assessment, and treatment of cutaneous lupus erythematosus, dermatomyositis, and scleroderma (systemic sclerosis, morphea) were presented by experts in each field and new developments discussed. In these rheumatic skin diseases, many clinical trials of novel therapies targeting cytokines, signaling molecules, plasmacytoid dendritic cells, B cells, and other molecules are currently underway, and standardization of outcome assessment was discussed. In addition, the selection of the therapeutic agents available for the diversity of each case is becoming more important, together with the ongoing pathophysiological analysis of the diseases. The achievements of this conference will further promote the development of clinical practice and research in rheumatic skin diseases through international exchange among researchers. We hope that by reporting a summary of the conference in this manuscript, we can share its contents with readers.

Lymphocyte-Peppered Sclerotic Collagen: An Additional Histological Clue in Lichen Sclerosus, Morphea, and Systemic Sclerosis.

BACKGROUND: "Line sign," "cookie cutter sign," "square biopsy sign," "high eccrine glands sign" have been previously described in morphoea and lichen sclerosus. We found focal areas of thickened collagen bundles with lymphocytes interspersed between them in several biopsies of these conditions. MATERIALS AND METHODS: We reviewed slides of sclerosing disorders obtained from the archives of the pathology department in our hospital for the period 2013-2019. RESULTS: A total of 73 slides including 40 of lichen sclerosus, 24 of morphea, 2 of lichen sclerosus-morphea overlap, and 7 of systemic sclerosis were evaluated. Lymphocytes were noted between sclerotic collagen bundles in 46 (63%) slides, being most common in lichen sclerosus (80%, 32/40) followed by morphea (50%, 12/24), whereas it was seen in one case each of lichen sclerosus with morphea overlap (50%, 1/2) and systemic sclerosis (14.3%, 1/7). The finding was noted in the upper dermis in 20 of 32 (62.5%) slides of lichen sclerosus and in both the superficial and deep dermis in 11 (91.7%) of 12 slides of morphea. CONCLUSION: Lymphocyte-peppered sclerotic collagen may be a useful histological clue to the diagnosis of lichen sclerosus, morphea, and systemic sclerosis.

Targeting human plasmacytoid dendritic cells through BDCA2 prevents skin inflammation and fibrosis in a novel xenotransplant mouse model of scleroderma.

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.

Methotrexate in Linear Scleroderma: Long-Term Efficacy in Fifty Children From a Single Pediatric Rheumatology Center.

OBJECTIVE: To study disease course and long-term outcome in children with linear scleroderma (SSc) treated with methotrexate (MTX) since diagnosis. METHODS: The present study was retrospective and cross-sectional and included consecutive children with linear SSc who were treated with MTX for >1 year and were followed up for at least 2 years. Disease course was analyzed by the number of relapses and treatment changes. Relapse-free survival was examined by Kaplan-Meier analysis, comparing patients with linear SSc and those with other juvenile localized scleroderma (JLS) disease subtypes. Disease activity and damage were assessed by the Localized Scleroderma Cutaneous Assessment Tool and thermography. RESULTS: Fifty patients with a mean follow-up duration of 7.8 years and a mean MTX treatment duration of 3.1 years were included. Sixteen percent of patients did not respond to the first course of MTX, and 16% had at least 1 flare. Complete remission was observed in 18.2% of patients who were followed up for 2-5 years, in 80.0% of patients followed up for 10 years, and in 87.5% of patients followed up for >10 years. No significant difference in relapse-free survival between patients with linear SSc and in 17 patients with other JLS disease subtypes was observed. Tissue damage was mild in 42% of patients, moderate in 32%, and severe in 26%. The correlations between severity of tissue damage and linear SSc subtype, disease duration, relapses, and remission were not significant. The relationships between treatment duration and disease relapses (P < 0.05) and severity of tissue damage (P < 0.005) were significant. CONCLUSION: Most patients with linear SSc who are treated with MTX achieve complete and long-lasting remission. Overall aesthetic and functional sequelae are moderate, most likely because tissue damage is established early and treatment likely stabilizes the damage. Early diagnosis and MTX treatment, as well as long-term monitoring, are crucial to improve outcome and promptly identify flares.

IFN-γ-Stimulated Apoptotic Keratinocytes Promote Sclerodermatous Changes in Chronic Graft-Versus-Host Disease.

Patients with graft-versus-host disease (GVHD) develop characteristic mucocutaneous phenomena consisting of erosive erythema with histopathological findings including interface dermatitis and keratinocyte (KC) death, resulting in widespread sclerodermatous changes. We found that KCs exhibit marked production of TGFß1 in skin lesions of chronic GVHD but not in those of acute GVHD. To further investigate the roles of KCs, the main targets of donor T cells, in sclerodermatous changes followed by interface dermatitis, we established a murine model of chronic GVHD-like sclerodermatous changes followed by acute GVHD-like mucocutaneous injury in genetically modified mice transferred with KC-specific CD8 T cells. Although transfer of granzyme B-deficient CD8 T cells did not result in either mucocutaneous injury or sclerodermatous changes in recipients, IFN-γ-deficient CD8 T-cell recipients developed severe acute mucocutaneous injury but milder sclerodermatous changes than wild-type CD8 T-cell recipients. Moreover, IFN-γ-deficient CD8 T-cell recipients had a lower expression of TGFß1 in the epidermis than the control. Murine primary KCs undergoing FasL-induced apoptosis and incubated with IFN-γ produced TGFß1, the production of which was inhibited by a pan-caspase inhibitor. Our results indicate that IFN-γ promotes TGFß1 production by apoptotic KCs, which mediates the development of widespread sclerodermatous changes in KC-targeting GVHD.

Coexistence of systemic and localized scleroderma: a systematic literature review and observational cohort study.

OBJECTIVE: SSc and localized sclerosis (LoS) are considered clinically distinct entities. We describe herein the coexistence of SSc and LoS by both a systematic literature review and an observational cohort study of unselected SSc patients. METHODS: Original studies documenting the coexistence of SSc and LoS were identified in three electronic databases by means of a systematic literature search according to the Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) guidelines. Additionally, the coexistence of SSc and LoS was studied in a prospective cohort of SSc patients visiting the Ghent University Scleroderma Unit for their yearly follow-up visit between January 2018 and January 2019. RESULTS: Five studies were finally included for quality appraisal and data extraction. The coexistence of SSc and LoS ranged between 2.4 and 7.4%. RP, scleroderma pattern on nailfold videocapillaroscopy (NVC) and the presence of SSc-specific antibodies were commonly observed in coexistent cases. Additionally, coexistence of SSc and LoS was found in 8/296 (2.7%) consecutive SSc patients of the Ghent University Scleroderma Unit. RP was present in 6/8 coexistent cases; a scleroderma pattern on NVC was observed in all coexistent cases, and SSc-specific antibodies (i.e. cenp-B) were found in 4/8 coexistent cases. CONCLUSION: This is the first systematic literature review with additional cohort evaluation investigating the coexistence of SSc and LoS. A relatively high overlap of SSc and LoS was revealed, which is peculiar because both are rare diseases.

Cosmetic treatment in patients with autoimmune connective tissue diseases: Best practices for patients with morphea/systemic sclerosis.

Morphea and systemic sclerosis are inflammatory, sclerosing disorders. Morphea primarily affects the dermis and subcutaneous fat, while systemic sclerosis typically involves the skin and internal organs. Functional impairment and cosmetic disfigurement are common in both diseases. Treatment options to mitigate disease progression remain limited. Both functional impairment and cosmetic deficits negatively impact quality of life and psychological well-being in this patient population. While the number of cosmetic procedures performed in the United States continues to rise each year, limited data exist regarding best practices for correcting aesthetic deficits caused by autoimmune conditions. There is scarce information to guide safety decisions regarding laser parameters, soft tissue augmentation, treatment intervals, and the concurrent use of immune-modifying or immune-suppressing medications. Given the fears of disease reactivation and exacerbation from postprocedural inflammation along with limited data, it is difficult for clinicians to provide evidence-based cosmetic treatment with realistic expectations with regard to short- and long-term outcomes. In the first article in this continuing medical education series, we attempt to address this practice gap.

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.

Regulation of skin fibrosis by RALDH1-producing dermal dendritic cells via retinoic acid-mediated regulatory T cell induction: A role in scleroderma.

BACKGROUND: Skin fibrosis of systemic sclerosis (SSc) is believed to be driven by complex processes including immune abnormalities, but the underlying immune response remains enigmatic. In particular, the role of dermal dendritic cells (DCs) is totally unknown. OBJECTIVE: We investigated the impact of CD103 loss on bleomycin-induced skin fibrosis because CD103 is a critical molecule determining DC phenotypes. METHODS: Bleomycin-induced skin fibrosis was generated with Cd103-/- mice. The alterations of tissue fibrosis and related inflammation were investigated by histologic examination, hydroxyproline assay, quantitative reverse transcription PCR and flow cytometry. SSc skin samples were evaluated by immunofluorescence. RESULTS: CD103 loss decreased bleomycin-induced dermal thickness and collagen contents, along with TGF-ß1 and CTGF suppression. Treg proportion was increased, while Th1/Th2/Th17 cell proportions were decreased in the skin of bleomycin-treated Cd103-/- mice. Bleomycin injection enhanced CD11b-CD103- DC proportion in wild-type mice, which was further augmented in Cd103-/- mice. Importantly, RALDH1/ALDH1A1 enzyme oxidizing retinaldehyde to retinoic acid, an inducer of Tregs, was preferentially expressed by CD11b-CD103- DCs and its expression levels were elevated in bleomycin-injected skin lesions, to a greater extent in Cd103-/- mice than in wild-type mice. Importantly, the number of RALDH1-positive DCs was decreased in the lesional skin of SSc patients and tended to inversely correlate with skin fibrosis severity. CONCLUSION: This study identified a critical role of dermal DCs as a regulator of Treg development through RALDH1 in bleomycin-treated mice and possibly in human SSc. This finding sheds new light on dermal DCs as a new therapeutic target of SSc.

Immunoglobulin G galactosylation levels are decreased in systemic sclerosis patients and differ according to disease subclassification.

Objectives: Scleroderma is a connective tissue immune disease that features collagen overproduction and can be categorized into two subtypes, localized scleroderma (LSc) and systemic sclerosis (SSc). SSc is clinically classified into two subsets: limited cutaneous (lcSSc) and diffuse cutaneous (dcSSc) SSc. The immunoglobulin G-galactosylation (IgG-Gal) ratio is abnormal in a number of immune diseases and has not been evaluated in SSc.Method: The study recruited 93 LSc patients, 298 SSc patients, and 436 healthy controls. N-glycans of purified IgG were obtained from plasma and detected by tandem mass spectrometry. The IgG-Gal ratio was measured by calculating the relative intensities of agalactosylated (G0), monogalactosyl (G1), and digalactosyl (G2) N-glycans according to the formula G0/(G1 + G2 × 2). Furthermore, we examined whether the IgG-Gal ratio differed between different subtypes of SSc.Results: The IgG-Gal ratio was significantly higher in SSc patients (1.139 ± 0.870) than in LSc patients (0.485 ± 0.280) and controls (0.395 ± 0.190). The IgG-Gal ratio successfully distinguished SSc patients from LSc and controls (area under the curve = 0.88 and 0.81, respectively). The IgG-Gal ratio was significantly higher in dcSSc patients than in lcSSc patients and increased along with increases in modified Rodnan skin score (p = 6.03 × 10-5, Pearson's coefficient = 0.26) and erythrocyte sedimentation rate (p = 2.95 × 10-10, Pearson's coefficient = 0.38).Conclusion: IgG-Gal ratios were abnormal in SSc patients and were associated with disease severity. The IgG-Gal ratio therefore shows potential as a biomarker for the diagnosis of SSc.

IL-17A Dissociates Inflammation from Fibrogenesis in Systemic Sclerosis.

IL-17A is abundant in scleroderma but its role in fibrogenesis is controversial. We interrogated the role of IL-17A in extracellular matrix deposition and inflammation by investigating its effects on keratinocytes and fibroblasts cross-talk and in organotypic skin cultures. Keratinocyte-conditioned media of resting, IL-17A-, and/or transforming growth factor-ß-primed primary keratinocytes were used to stimulate healthy donors and scleroderma fibroblasts. Alternatively, organotypic cultures of full human skin were challenged with these cytokines. Keratinocyte-conditioned media tilted the balance of col-I to matrix metalloproteinase-1 production by fibroblasts in favor of matrix metalloproteinase-1, significantly more so in healthy donors than in scleroderma, resulting in enhanced extracellular matrix turnover, further increased by IL-17A. In organotypic skin, transforming growth factor-ß induced an extensive pro-fibrotic gene signature, including the enhanced expression of several collagen genes associated with Wnt signaling. IL-17A strongly promoted the expression of pro-inflammatory genes, with no direct effects on collagen genes, and attenuated Wnt signaling induced by transforming growth factor-ß. In this model, at the protein level, IL-17A significantly decreased col-I production. Our data strongly support a pro-inflammatory and antifibrogenic activity of IL-17A in the context of keratinocyte-fibroblast interaction and in full skin. These data help in directing and interpreting targeted therapeutic approaches in scleroderma.

Systemic sclerosis and urinary symptoms: a complex pathophysiology.

Lower urinary tract symptoms (LUTS) have long been overlooked in systemic sclerosis (SSc). However, they are out of proportion of what would be expected based on age, sex, and presence of usual risk factors. Thus, there must be specific scleroderma-related mechanisms to result in LUTS. Fibrosis, nervous involvement (notably, dysautonomia), early signs of menopauses, and functional restriction play certainly a role, but available evidence shows inconsistent results. Thus, these factors are not sufficient to explain all aspect of LUTS in SSc. In vitro experiments point out a promising alternative mechanism, already observed in other rheumatologic diseases: an antibody-mediated etiology. However, more research is needed to better understand the pathophysiology of LUTS in SSc and develop specific treatment.

Adipose-derived stromal/stem cells successfully attenuate the fibrosis of scleroderma mouse models.

AIM: Systemic sclerosis (SSc) is an autoimmune disease characterized by skin and lung fibrosis. Although SSc has a high mortality risk, an effective treatment for the disease has not been established yet. Mesenchymal stromal/stem cells (MSCs) are multipotential nonhematopoietic progenitor cells that have the ability to regulate immune responses. Adipose-derived stromal/stem cells (ASCs), one of the types of MSCs, have the advantage of accessibility and potent immunomodulatory effects when compared with other MSCs, such as bone marrow-derived MSCs. This study aimed to investigate the antifibrotic effect of ASCs in scleroderma mouse models, including bleomycin-induced scleroderma and sclerodermatous chronic graft-versus-host disease (Scl-cGVHD) models. METHOD: ASCs were intravenously administered to a bleomycin-induced scleroderma or Scl-cGVHD model on day 0. We compared the skin and lung fibrosis of scleroderma model mice between the ASC-treated group and control group. RESULTS: Administration of ASCs attenuated the skin and lung fibrosis of bleomycin-induced scleroderma and Scl-cGVHD model mice compared to that in the control mice. Immunohistochemical staining showed that ASCs suppressed the infiltration of CD4+ , CD8+ T cells and macrophages into the dermis of bleomycin model mice compared to that in control mice. In addition, ASCs attenuated the messenger RNA expression of collagen and fibrogenic cytokines, such as interleukin (IL)-6 and IL-13, in the skin of bleomycin model mice. ASCs also reduced the frequency of fibrogenic cytokine-producing CD4+ T cells and effector B cells in the spleen of bleomycin model mice. CONCLUSION: ASCs could prove to be a potential therapeutic agent for use in patients with SSc.

Fat Grafting for the Treatment of Scleroderma.

BACKGROUND: Scleroderma is a chronic connective tissue disease that results in fibrosis of the skin and internal organs. Although internal organ involvement corresponds with poor prognosis, systemic agents are effective at improving the effects of scleroderma on internal organs. In contrast, skin manifestations are universally present in all patients diagnosed with scleroderma, yet no systemic agents have been shown to be successful. Fat grafting has been shown to improve skin quality and improve contour irregularities and may be helpful in the treatment of patients with scleroderma. METHODS: The authors performed a thorough review of the pathophysiology of scleroderma and the current treatment options for scleroderma. The efficacy of fat grafting for the treatment of scleroderma and the mechanism by which fat grafting improves outcomes was also discussed. RESULTS: Scleroderma is characterized by chronic inflammation and vascular compromise that leads to fibrosis of the skin and internal organs. Fat grafting has recently been the focus of significant basic science research. It has been shown to reduce inflammation, reduce fibrosis by limiting extracellular matrix proteins and increasing collagenase activity, and provide structural support through stem cell proliferation and differentiation. The adipocytes, adipose stem cells, endothelial cells, and vascular smooth muscle cells in the processed fat likely contribute to the effectiveness of this treatment. CONCLUSIONS: Fat grafting in scleroderma patients likely improves skin manifestations by recreating fullness, correcting contour deformities, and improving skin quality. The injected fat provides a mixture of cells that influences the recipient site, resulting in improved outcomes.

Autoantibodies in Morphea: An Update.

Skin autoimmune conditions belong to a larger group of connective tissue diseases and primarily affect the skin, but might also involve underlying tissues, such as fat tissue, muscle, and bone. Autoimmune antibodies (autoantibodies) play a role in autoimmune skin diseases, such as localized scleroderma also termed morphea, and systemic scleroderma, also called systemic sclerosis (SSc). The detailed studies on the biological role of autoantibodies in autoimmune skin diseases are limited. This results in a few available tools for effective diagnosis and management of autoimmune skin diseases. This review aims to provide an update on the detection and most recent research on autoantibodies in morphea. Several recent studies have indicated the association of autoantibody profiles with disease subtypes, damage extent, and relapse potential, opening up exciting new possibilities for personalized disease management. We discuss the role of existing autoantibody tests in morphea management and the most recent studies on morphea pathogenesis. We also provide an update on novel autoantibody biomarkers for the diagnosis and study of morphea.

Immunopathogenesis of Pediatric Localized Scleroderma.

Localized scleroderma (LS) is a complex disease characterized by a mixture of inflammation and fibrosis of the skin that, especially in the pediatric population, also affects extracutaneous tissues ranging from muscle to the central nervous system. Although developmental origins have been hypothesized, evidence points to LS as a systemic autoimmune disorder, as there is a strong correlation to family history of autoimmune disease, the presence of shared HLA types with rheumatoid arthritis, high frequency of auto-antibodies, and elevated circulating chemokines and cytokines associated with T-helper cell, IFNγ, and other inflammatory pathways. This inflammatory phenotype of the peripheral blood is reflected in the skin via microarray, RNA Sequencing and tissue staining. Research is underway to identify the key players in the pathogenesis of LS, but close approximation of inflammatory lymphocytic and macrophage infiltrate with collagen and fibroblasts deposition supports the notion that LS is a disease of inflammatory driven fibrosis. The immune system is dynamic and undergoes changes during childhood, and we speculate on how the unique features of the immune system in childhood could potentially contribute to some of the differences in LS between children and adults. Interestingly, the immune phenotype in pediatric LS resembles to some extent the healthy adult cellular phenotype, possibly supporting accelerated maturation of the immune system in LS. We discuss future directions in better understanding the pathophysiology of and how to better treat pediatric LS.