Cross-Comparison of Inflammatory Skin Disease Transcriptomics Identifies PTEN as a Pathogenic Disease Classifier in Cutaneous Lupus Erythematosus.

Tissue transcriptomics is used to uncover molecular dysregulations underlying diseases. However, the majority of transcriptomics studies focus on single diseases with limited relevance for understanding the molecular relationship between diseases or for identifying disease-specific markers. In this study, we used a normalization approach to compare gene expression across nine inflammatory skin diseases. The normalized datasets were found to retain differential expression signals that allowed unsupervised disease clustering and identification of disease-specific gene signatures. Using the NS-Forest algorithm, we identified a minimal set of biomarkers and validated their use as diagnostic disease classifier. Among them, PTEN was identified as being a specific marker for cutaneous lupus erythematosus and found to be strongly expressed by lesional keratinocytes in association with pathogenic type I IFNs. In fact, PTEN facilitated the expression of IFN-ß and IFN-κ in keratinocytes by promoting activation and nuclear translocation of IRF3. Thus, cross-comparison of tissue transcriptomics is a valid strategy to establish a molecular disease classification and to identify pathogenic disease biomarkers.

Bioinformatics analyses of gene expression profile to identify pathogenic mechanisms for COVID-19 infection and cutaneous lupus erythematosus.

Objective: The global mortality rates have surged due to the ongoing coronavirus disease 2019 (COVID-19), leading to a worldwide catastrophe. Increasing incidents of patients suffering from cutaneous lupus erythematosus (CLE) exacerbations after either contracting COVID-19 or getting immunized against it, have been observed in recent research. However, the precise intricacies that prompt this unexpected complication are yet to be fully elucidated. This investigation seeks to probe into the molecular events inciting this adverse outcome. Method: Gene expression patterns from the Gene Expression Omnibus (GEO) database, specifically GSE171110 and GSE109248, were extracted. We then discovered common differentially expressed genes (DEGs) in both COVID-19 and CLE. This led to the creation of functional annotations, formation of a protein-protein interaction (PPI) network, and identification of key genes. Furthermore, regulatory networks relating to these shared DEGs and significant genes were constructed. Result: We identified 214 overlapping DEGs in both COVID-19 and CLE datasets. The following functional enrichment analysis of these DEGs highlighted a significant enrichment in pathways related to virus response and infectious disease in both conditions. Next, a PPI network was constructed using bioinformatics tools, resulting in the identification of 5 hub genes. Finally, essential regulatory networks including transcription factor-gene and miRNA-gene interactions were determined. Conclusion: Our findings demonstrate shared pathogenesis between COVID-19 and CLE, offering potential insights for future mechanistic investigations. And the identification of common pathways and key genes in these conditions may provide novel avenues for research.

German Shorthaired Pointer dogs with exfoliative cutaneous lupus erythematosus develop immune-complex membranous glomerulonephropathy.

German Shorthaired Pointer (GSHP) dogs with a UNC93B1 gene mutation develop exfoliative cutaneous lupus erythematosus (ECLE) and kidney disease resembling lupus nephritis in humans. The objective of this study was to characterize the kidney disease by light microscopy, immunofluorescence, and electron microscopy in a population of GSHP dogs with ECLE. Medical records were reviewed, and light microscopy of kidneys from 7 GSHP dogs with a previous histologic diagnosis of ECLE was performed. Immunofluorescence of fresh-frozen kidney from 1 dog and transmission electron microscopy of kidney from that dog and 2 additional dogs were performed. Five of 7 dogs had proteinuria diagnosed by urinalysis or urine protein-to-creatinine ratio. Two of 7 dogs were intermittently hypoalbuminemic, and none were azotemic. Histologic findings included early (2 dogs) to late (5 dogs) membranous glomerulonephropathy characterized by mild-to-severe glomerular capillary loop thickening and tubular proteinosis. In all 7 cases, trichrome staining revealed red granular immune deposits on the subepithelial surface of the glomerular basement membrane. Immunofluorescence revealed strong granular labeling for immunoglobulins and complement protein C3. Electron microscopy demonstrated subepithelial electron-dense immune deposits encircled by the remodeled glomerular basement membrane. These findings are diagnostic of immune-complex membranous glomerulonephropathy and are similar to class V lupus in humans. This cohort of GSHP dogs with ECLE developed immune-complex membranous glomerulonephropathy, which we hypothesize is a manifestation of systemic lupus erythematosus. GSHP dogs with ECLE should undergo clinical evaluation of renal function for early identification and treatment.

Rapid efficacy of anifrolumab across multiple subtypes of recalcitrant cutaneous lupus erythematosus parallels changes in discrete subsets of blood transcriptomic and cellular biomarkers.

BACKGROUND: Observations with rituximab suggest B-cell independent mechanisms of cutaneous lupus erythematosus (CLE) in systemic lupus erythematosus (SLE), especially discoid lupus erythematosus (DLE). Type-I interferon receptor blockade with anifrolumab shows efficacy in SLE, but efficacy for cutaneous disease of specific morphologies has not been studied. Interferon has pleotropic immune effects and it is unknown which of these are critical to therapeutic response. OBJECTIVES: We evaluated clinical efficacy and quality-of-life impact of type-I interferon-blockade in: (i) rituximab-refractory CLE; (ii) DLE and other morphologies and (iii) transcriptomic and flow cytometric biomarkers. METHODS: We conducted a prospective single-centre study of anifrolumab in refractory mucocutaneous SLE. CLE Disease Area and Severity Index (CLASI) activity score, health-related quality of life, 96-probe TaqMan® gene expression analysis capturing key SLE blood transcriptome signatures, and eight-colour flow cytometry were undertaken at baseline, 1, 3 and 6 months. RESULTS: Seven patients [DLE (n = 5), chilblain lupus erythematosus (n = 1), subacute CLE (n = 1)] were evaluated. The median number of prior therapies was six (range 3-15), including rituximab in six of seven patients. Median CLASI-A showed rapid and sustained improvement from 17 at baseline to 6 (P = 0.016) at 1 month and 0 (P < 0.001) by 3 months. The median percentage reduction in CLASI-A at 3 months was 60%. Significant improvements were observed in Dermatology Life Quality Index scores (P < 0.001), EuroQol 5D visual analogue scale (P = 0.002) and LupusQoL fatigue, image and planning domains (P ≤ 0.05). One patient discontinued treatment owing to severe herpes zoster. Clinical responses paralleled discrete suppression of interferon-stimulated genes (ISGs) from SLE blood transcriptome module M1.2 with more varied downregulation in other interferon modules. Myeloid and inflammation-annotated genes remained upregulated throughout treatment. Intermediate monocytes (CD14++CD16+) reduced to normal levels during therapy (P = 0.014), while other flow subsets showed no substantive changes. CONCLUSIONS: These data indicate rapid efficacy of anifrolumab in DLE and rituximab-resistant CLE. Response is associated with suppression of a subset of ISGs and decline in intermediate monocytes. Suppression of all ISGs or the wider SLE blood transcriptome is not required for response.

Downregulation of miR-885-5p Promotes NF-κB Pathway Activation and Immune Recruitment in Cutaneous Lupus Erythematosus.

Cutaneous lupus erythematosus (CLE) has a specific microRNA expression profile. MiR-885-5p has been found to be downregulated in the epidermis of CLE lesions; however, its biological role in the disease has not been studied. In this study, we show that miR-885-5p is markedly reduced in CLE keratinocytes (KCs) with IFN-α and UVB being strong miR-885-5p regulators in vitro. Microarray expression profiling of anti‒miR-885-5p‒transfected KCs identified PSMB5 as a direct target. Specific inhibition of miR-885-5p increased epidermal proliferation by modulating keratin 16 gene K16, BIRC5, TP63, and CDK4 proliferative genes and promoted NF-κB signaling pathway in human primary KCs by increasing IκBα degradation. Silencing PSMB5 rescued the effect of miR-885-5p inhibition, indicating that miR-885-5p regulates proliferation and NF-κB activation by targeting PSMB5 in KCs. In addition, inhibition of miR-885-5p increased the ability of KCs to attract leukocytes in a PSMB5-independent manner. We identified TRAF1 as another direct target, and its silencing reduced leukocyte migration. Collectively, our findings suggest that UVB and IFN-ɑ downregulate miR-885-5p in CLE KCs, leading to epidermal inflammation by NF-κB activity enhancement and proliferation through PSMB5 and immune recruitment through TRAF1. Our data indicate that miR-885-5p is a potential therapeutic target in CLE.

Single-cell transcriptome reveals immunopathological cell composition of skin lesions in subacute cutaneous lupus erythematosus.

Subacute cutaneous lupus erythematosus (SCLE) is a clinical subtype of cutaneous lupus erythematosus with psoriatic-like or annular papules with scaly erythemas, the pathological mechanism of which is poorly understood. To investigate the immune pathogenesis of SCLE, we performed single-cell RNA sequencing (scRNA-seq) of SCLE skin lesions and integrated the scRNA-seq data from skin tissues of healthy controls (HCs). Our results identified expanded fibroblasts and keratinocytes subtypes, abnormally activated lymphocyte and inflammatory M1 macrophages in SCLE. In SCLE, stromal cells, such as keratinocytes and fibroblasts, showed enhanced chemotactic functions for recruiting immune cells. Importantly, interferon-related genes were identified as key intermediate genes in the potential trajectory of fibroblasts, keratinocytes, and B cells from HCs to SCLE. Our investigation provides a comprehensive description of cell composition in SCLE and highlights several important clues for understanding the pathogenesis of SCLE.

Identification of Significant Genes and Pathways for the Chronic and Subacute Cutaneous Lupus Erythematosus via Bioinformatics Analysis.

Background: Chronic cutaneous lupus erythematosus (CCLE) and subacute cutaneous lupus erythematosus (SCLE) are both common variants of cutaneous lupus erythematosus (CLE) that mainly involve the skin and mucous membrane. Oral mucosal involvement is frequently observed in patients of CLE. Despite that they have different clinicopathological features, whether there is a significant difference in pathogenesis between them remains unclear. Herein, we investigated specific genes and pathways of SCLE and CCLE via bioinformatics analysis. Methods: Microarray expression datasets of GSE109248 and GSE112943 were both retrieved from the GEO database. Differentially expressed genes (DEGs) between CCLE or SCLE skin tissues and health controls were selected by GEO2R. Common DEGs were picked out via the Venn diagram software. Then, functional enrichment and PPI network analysis were conducted, and the top 10 key genes were identified via Cytohubba. Results: Totally, 176 DEGs of SCLE and 287 DEGs of CCLE were identified. The GO enrichment and KEGG analysis of DEGs of SCLE is significantly enriched in the response to virus, defense response to virus, response to IFN-gamma, cellular response to IFN-γ, type I IFN signaling pathway, chemokine activity, chemokine receptor binding, NOD-like receptor signaling pathway, etc. The GO enrichment and KEGG analysis of DEGs of CCLE is significantly enriched in the response to virus, regulation of multiorganism process, negative regulation of viral process, regulation of lymphocyte activation, chemokine receptor binding, CCR chemokine receptor binding, NOD-like receptor signaling pathway, etc. The top 10 hub genes of SCLE and CCLE, respectively, include STAT1, CXCL10, IRF7, ISG15, and RSAD2 and CXCL10, IRF7, IFIT3, CTLA4, and ISG15. Conclusion: Our finding suggests that SCLE and CCLE have the similar potential key genes and pathways and majority of them belong to IFN signatures and IFN signaling pathway. Besides, the NOD-like receptor signaling pathway might also have an essential role in the pathogenesis of SCLE and CCLE. Together, the identified genes and signaling pathways have enhanced our understanding of the mechanism underlying the occurrence and development of both SCLE and CCLE.

IL-33/ST2 Activation Is involved in Ro60-Regulated Photosensitivity in Cutaneous Lupus Erythematosus.

Interleukin- (IL-) 33 contributes to various inflammatory processes. IL-33/ST2 activation participates in systemic lupus erythematous via binding to the receptor of Suppression of Tumorigenicity 2 protein (ST2). However, whether IL-33/ST2 interferes with the nosogenesis of cutaneous lupus erythematosus (CLE) has not been reported so far. Herein, we proposed to disclose the impacts on IL-33/ST2 activation and Ro60 on CLE and their potential implications in the photosensitization of CLE cells. IL-33, ST2, and Ro60 in CLE patients' skin lesions were detected. Murine keratinocytes stimulated with or without IL-33 were irradiated by ultraviolet B (UVB), and the levels of Ro60 and inflammation markers were determined. Keratinocytes were cocultured with J774.2 macrophages and stimulated with IL-33 for analysis of chemostasis. The results identified that IL-33, ST2, and downstream inflammation markers were significantly upregulated in CLE lesions with Ro60 overexpression. Additionally, IL-33 treatment promoted the upregulation of Ro60 induced by UVB treatment in murine keratinocytes. Moreover, IL-33 stimulates keratinocytes to induce macrophage migration via enhancing the generation of the chemokine (C-C motif) ligands 17 and 22. Meanwhile, the silencing of ST2 or nuclear factor-kappa B (NF-κB) suppression abolished IL-33-induced upregulation of Ro60 in keratinocytes. Similarly, the inhibition of SOX17 expression was followed by downregulation of Ro60 in keratinocytes following IL-33 stimulation. In addition, UVB irradiation upregulated SOX17 in keratinocytes. Conclusively, the IL-33/ST2 axis interferes with Ro60-regulated photosensitization via activating the NF-κB- and PI3K/Akt- and SOX17-related pathways.

A Novel Type I Interferon Primed Dendritic Cell Subpopulation in TREX1 Mutant Chilblain Lupus Patients.

Heterozygous TREX1 mutations are associated with monogenic familial chilblain lupus and represent a risk factor for developing systemic lupus erythematosus. These interferonopathies originate from chronic type I interferon stimulation due to sensing of inadequately accumulating nucleic acids. We here analysed the composition of dendritic cell (DC) subsets, central stimulators of immune responses, in patients with TREX1 deficiency. We performed single-cell RNA-sequencing of peripheral blood DCs and monocytes from two patients with familial chilblain lupus and heterozygous mutations in TREX1 and from controls. Type I interferon pathway genes were strongly upregulated in patients. Cell frequencies of the myeloid and plasmacytoid DC and of monocyte populations in patients and controls were similar, but we describe a novel DC subpopulation highly enriched in patients: a myeloid DC CD1C+ subpopulation characterized by the expression of LMNA, EMP1 and a type I interferon- stimulated gene profile. The presence of this defined subpopulation was confirmed in a second cohort of patients and controls by flow cytometry, also revealing that an increased percentage of patient's cells in the subcluster express costimulatory molecules. We identified a novel type I interferon responsive myeloid DC subpopulation, that might be important for the perpetuation of TREX1-induced chilblain lupus and other type I interferonopathies.

Prominent B-Cell Signature Differentiates Discoid from Subacute Cutaneous Lupus Erythematosus.

Although B cells account for a significant proportion of the lymphocytic infiltrate in discoid lupus erythematosus (DLE), their contribution to pathogenesis is unknown. In this study, we compare the immune landscape of 17 subjects with DLE with that of 21 subjects with subacute cutaneous lupus erythematosus using transcriptomic and histologic analyses of lesional skin. A few of the subjects (3 of 17 subjects with DLE, and 5 of 21 subjects with subacute cutaneous lupus erythematosus) had concomitant systemic lupus erythematosus. Using a modified Autoimmune Profiling Panel (NanoString Technologies, Seatle, WA), we show that B-cell‒specific genes, including canonical pan‒B cell markers CD19 (P = 0.0060), MS4A1 (CD20) (P = 0.0047), and CD79a (P = 0.0201), are among the most upregulated genes in DLE. Numerous other genes encoding B-cell‒associated proteins, including Igs, BAFF receptors, and FCRL family members, are similarly enriched. Relative cell type scoring reveals that among various inflammatory cell types, only B cells are more prevalent in DLE. Digital whole-image slide analysis of immunohistochemistry for B cells (CD20) and T cells (CD3) supports our gene expression findings of a disproportionately greater B-cell infiltrate in DLE lesions. Overall, this study identifies a B-cell‒predominant signature unique to DLE and highlights the importance of studying the role of cutaneous B cells in DLE pathogenesis.

Immunogenetics of Lupus Erythematosus.

Lupus erythematosus (LE) is a heterogeneous disease with a wide range of manifestations ranging from localized lesions in cutaneous lupus erythematosus (CLE) to severe disseminated disease in systemic lupus erythematosus (SLE).Lupus results from a complex interaction between genetic and epigenetic backgrounds and environmental triggers that cause loss of tolerance to self-antigens and the formation of autoantibodies. Genetic susceptibility plays a key role in the pathogenesis of lupus erythematosus. In most cases, multiple common alleles with modest effect sizes are combined to result in the polygenic inheritance of the disease but monogenic variants of lupus have also been described. Genes from the innate and adaptive immune system along with genes involved in apoptosis and immunoglobulin clearance have been linked to SLE. This chapter aims to explore the functions of these genes and their contribution to the pathogenesis of the disease.

Black patients with cutaneous lupus are associated with positive family history of cutaneous lupus and systemic lupus.

OBJECTIVES: Various genetic polymorphisms have been associated with an increased risk of cutaneous lupus erythematosus (CLE). However, it is not fully known how often positive family histories occur in patients with CLE. The aims of this study are to determine the rate of positive family history among patients with CLE and to identify risk factors associated with positive family history. METHODS: A retrospective cohort study was conducted among 338 patients with CLE seen in outpatient dermatology clinics in a tertiary referral centre in Dallas, Texas. The primary outcome was positive family history of CLE and/or SLE, as defined by the presence of self-reported CLE and/or SLE in first-degree or more distant relatives of a patient. Univariate analyses were performed to identify risk factors associated with positive family history of CLE and/or SLE in patients with CLE. Multivariable logistic regression analyses were performed to determine significant predictors of positive family history of CLE and/or SLE. RESULTS: 34% (n=114) of patients reported positive family history of CLE and/or SLE. 7% (n=23) of patients with CLE had relatives with CLE, with 5% (n=18) having a first-degree relative with CLE. 30% (n=102) of patients with CLE had relatives with SLE, and 15% (n=52) had a first-degree relative with SLE. Black patients were more likely to have positive family history of CLE and/or SLE (OR 2.13, 95% CI 1.23 to 3.69, p=0.007). CONCLUSIONS: More patients with CLE had positive family history of SLE than CLE. Black patients with CLE were more likely to have a relative with CLE and/or SLE. Providers can use this information to counsel patients with CLE on the risk of other family members having CLE and/or SLE. These data may help identify potentially new genetic polymorphisms associated with positive family history.

Unusual severe radiation-induced toxicity in a patient with discoid lupus erythematosus: A case report and critical review of the literature.

Data on the incidence and severity of radiation-induced toxicity in patients with systemic and/or cutaneous lupus erythematosus (SLE/CLE) are very limited. After reporting the case of a patient who experienced major toxicity and CLE flare in the irradiated area following breast irradiation, we conducted a comprehensive literature review of available data in this setting. The few retrospectives studies which have evaluated both the risk of toxicity in SLE/CLE patients and/or the potential induction or reactivation of SLE/CLE with radiotherapy have not shown differences between SLE/CLE patients and controls. Several other factors such as concurrent chemotherapy, a particular genetic background, or lupus treatments (essentially hydroxychloroquine) can explain severe radiation-induced toxicity. Therefore, patients with SLE/CLE should be irradiated like patients without SLE/CLE, with close monitoring during radiotherapy if other risk factors exist. Further studies examining a larger number of patients would probably allow a better understanding of the radiosensitivity of these patients.

The Overlap between Genetic Susceptibility to COVID-19 and Skin Diseases.

Coronavirus disease 2019 (COVID-19) mainly affects the respiratory system, but the involvement of other organ systems has also been commonly reported. Acute acro-ischemia or chilblain like lesions were among the first recognized dermatological presentations of COVID-19. Though the occurrence of such lesions has been attributed to the similar interferon-1 mediated immune response in both COVID-19 and systemic lupus erythematosus, we propose another possible explanation based on a common genetic background. In a recent genome-wide association study, the 3p21.31 region was found to be associated with COVID-19 severity. This region also contains the TREX1 gene. Missense mutations of the TREX1 gene are responsible for familial chilblain lupus and its genetic polymorphisms have been implicated in the pathogenesis of systemic lupus erythematosus. Based on this observation, herein we have reviewed other COVID-19 risk loci for potential overlap with dermatological conditions.

Photosensitivity and cGAS-Dependent IFN-1 Activation in Patients with Lupus and TREX1 Deficiency.

The exonuclease TREX1 safeguards the cells against DNA accumulation in the cytosol and thereby prevents innate immune activation and autoimmunity. TREX1 mutations lead to chronic DNA damage and cell-intrinsic IFN-1 response. Associated disease phenotypes include Aicardi‒Goutières syndrome, familial chilblain lupus, and systemic lupus erythematosus. Given the role of UV light in lupus pathogenesis, we assessed sensitivity to UV light in patients with lupus and TREX1 mutation by phototesting, which revealed enhanced photosensitivity. TREX1-deficient fibroblasts and keratinocytes generated increased levels of ROS in response to UV irradiation as well as increased levels of 8-oxo-guanine lesions after oxidative stress. Likewise, the primary UV-induced DNA lesions cyclobutane pyrimidine dimers were induced more strongly in TREX1-deficient cells. Further analysis revealed that single-stranded DNA regions, frequently formed during DNA replication and repair, promote cyclobutane pyrimidine dimer formation. Together, this resulted in a strong UV-induced DNA damage response that was associated with a cGAS-dependent IFN-1 activation. In conclusion, these findings link chronic DNA damage to photosensitivity and IFN-1 production in TREX1 deficiency and explain the induction of disease flares on UV exposure in patients with lupus and TREX1 mutation.

Proteome study of cutaneous lupus erythematosus (CLE) and dermatomyositis skin lesions reveals IL-16 is differentially upregulated in CLE.

BACKGROUND: The objective of the study was to explore the disease pathways activated in the inflammatory foci of skin lesions in cutaneous lupus erythematosus (CLE) and dermatomyositis (DM). METHODS: Skin biopsies acquired from active CLE and DM lesions, patient (PC), and also healthy controls (HC) were investigated. Biopsy sections were examined by a pathologist, inflammatory foci were laser micro-dissected and captured, and proteins within captured tissue were detected in an unbiased manner by mass spectrometry. Protein pathway analysis was performed by the string-db.org platform. Findings of interest were confirmed by immunohistochemistry (IHC). RESULTS: Proteome investigation identified abundant expression of interferon-regulated proteins (IRP) as a common feature of CLE and DM. Interleukin (IL)-16 was the only abundant cytokine differentially expressed in CLE compared to DM. Caspase-3, an enzyme that cleaves IL-16 into its active form, was detected in low levels. Significantly higher proportion of IL-16- and caspase-3-positive cells was identified in CLE lesions in comparison with DM, PC, and HC. Proteomic results indicate more abundant complement deposition in CLE skin lesions. CONCLUSIONS: Using unbiased mass spectrometry investigation of CLE and DM inflammatory infiltrates, we confirmed that high IRP expression is a common feature of both CLE and DM, while IL-16 is the only differentially expressed cytokine in CLE. IHC confirmed high expression of IL-16 and caspase-3 in CLE. Our novel molecular findings indicate that IL-16 detection could be useful in differential diagnostics between the two conditions that can display similar histopathological appearance. IL-16 could be of interest as a future therapeutic target for CLE.

Modular gene analysis reveals distinct molecular signatures for subsets of patients with cutaneous lupus erythematosus.

BACKGROUND: Cutaneous lupus erythematosus (CLE) is a heterogeneous autoimmune disease with clinical sequelae such as itching, dyspigmentation and scarring. OBJECTIVES: We applied a previously described modular analysis approach to assess the molecular heterogeneity of patients with CLE. METHODS: Whole-blood transcriptomes of RNA sequencing data from a racially and ethnically diverse group of patients with CLE (n = 62) were used to calculate gene co-expression module scores. An unsupervised cluster analysis and k-means clustering based on these module scores were then performed. We used Fisher's exact tests and Kruskal-Wallis tests to compare characteristics between patient clusters. RESULTS: Six unique clusters of patients with CLE were identified from the cluster analysis. We observed that seven inflammation modules were elevated in two clusters of patients with CLE. Additionally, these clusters were characterized by interferon, neutrophil and cell-death signatures, suggesting that interferon-related proteins, neutrophils and cell-death processes could be driving the inflammatory response in these subgroups. Three different clusters had a predominant T-cell signature, which were supported by lymphocyte counts. CONCLUSIONS: Our data support a diverse molecular profile in CLE that further adds to the clinical variations of this skin disease, and may affect disease course and treatment selection. Future studies with a larger and diverse cohort of patients with CLE are warranted to confirm these findings.

MicroRNAs in Several Cutaneous Autoimmune Diseases: Psoriasis, Cutaneous Lupus Erythematosus and Atopic Dermatitis.

MicroRNAs (miRNAs) are endogenous small non-coding RNA molecules that regulate the gene expression at a post-transcriptional level and participate in maintaining the correct cell homeostasis and functioning. Different specific profiles have been identified in lesional skin from autoimmune cutaneous diseases, and their deregulation cause aberrant control of biological pathways, contributing to pathogenic conditions. Detailed knowledge of microRNA-affected pathways is of crucial importance for understating their role in skin autoimmune diseases. They may be promising therapeutic targets with novel clinical implications. They are not only present in skin tissue, but they have also been found in other biological fluids, such as serum, plasma and urine from patients, and therefore, they are potential biomarkers for the diagnosis, prognosis and response to treatment. In this review, we discuss the current understanding of the role of described miRNAs in several cutaneous autoimmune diseases: psoriasis (Ps, 33 miRNAs), cutaneous lupus erythematosus (CLE, 2 miRNAs) and atopic dermatitis (AD, 8 miRNAs). We highlight their role as crucial elements implicated in disease pathogenesis and their applicability as biomarkers and as a novel therapeutic approach in the management of skin inflammatory diseases.

Oxidative DNA Damage Accelerates Skin Inflammation in Pristane-Induced Lupus Model.

Systemic Lupus Erythematosus (SLE) is a chronic inflammatory autoimmune disease in which type I interferons (IFN) play a key role. The IFN response can be triggered when oxidized DNA engages the cytosolic DNA sensing platform cGAS-STING, but the repair mechanisms that modulate this process and govern disease progression are unclear. To gain insight into this biology, we interrogated the role of oxyguanine glycosylase 1 (OGG1), which repairs oxidized guanine 8-Oxo-2'-deoxyguanosine (8-OH-dG), in the pristane-induced mouse model of SLE. Ogg1-/- mice showed increased influx of Ly6Chi monocytes into the peritoneal cavity and enhanced IFN-driven gene expression in response to short-term exposure to pristane. Loss of Ogg1 was associated with increased auto-antibodies (anti-dsDNA and anti-RNP), higher total IgG, and expression of interferon stimulated genes (ISG) to longer exposure to pristane, accompanied by aggravated skin pathology such as hair loss, thicker epidermis, and increased deposition of IgG in skin lesions. Supporting a role for type I IFNs in this model, skin lesions of Ogg1-/- mice had significantly higher expression of type I IFN genes (Isg15, Irf9, and Ifnb). In keeping with loss of Ogg1 resulting in dysregulated IFN responses, enhanced basal and cGAMP-dependent Ifnb expression was observed in BMDMs from Ogg1-/- mice. Use of the STING inhibitor, H151, reduced both basal and cGAMP-driven increases, indicating that OGG1 regulates Ifnb expression through the cGAS-STING pathway. Finally, in support for a role for OGG1 in the pathology of cutaneous disease, reduced OGG1 expression in monocytes associated with skin involvement in SLE patients and the expression of OGG1 was significantly lower in lesional skin compared with non-lesional skin in patients with Discoid Lupus. Taken together, these data support an important role for OGG1 in protecting against IFN production and SLE skin disease.