Immunopathogenesis of skin injury in systemic lupus erythematosus

Vacuoles, E1 enzyme, X-linked, autoinflammatory, somatic (VEXAS) syndrome in a patient with subacute cutaneous lupus (SCLE)

A man in his 60s suffered from refractory, biopsy-proven subacute cutaneous lupus erythematosus that required chronic, moderate dose steroids to manage. His rash was accompanied by arthralgias and negative autoantibody testing. His subacute lupus erythematosus (SCLE) was responsive to tofacitinib, but thrombotic complications limited the use of this medication. He continued prednisone 20 mg daily to manage his symptoms until treatment with anifrolumab completely cleared his skin. During a subsequent prednisone taper, he developed a macrocytic anaemia and elevated liver function tests that continued to progress. Ultimately, a bone marrow biopsy and myeloid next-generation sequencing revealed cellular vacuoles and UBA1 gene mutation, respectively, consistent with a diagnosis of VEXAS (vacuoles, E1 enzyme, X-linked, autoinflammatory, somatic) syndrome. We believe the chronic steroid use to control his SCLE masked the underlying diagnosis for many years.

Sunscreen use associated with elevated prevalence of anti-nuclear antibodies in U.S. adults

BACKGROUND

Antinuclear antibody (ANA) prevalence in the U.S. population increased from 1988 to 2012, especially in white and more educated individuals. In adults ages 20-39 years from the National Health and Nutrition Examination Survey (NHANES) 2003-2004 and 2011-2012, ANA prevalence was previously associated with urinary concentrations of a common sunscreen ingredient, benzophenone 3, measured in winter. Spot urines may not capture relevant chronic exposures, thus we examined whether ANA was related to sunscreen use.

METHODS

In a cross-sectional study of adults ages 20-59 (N = 416 ANA positive, 2656 ANA negative, by Hep-2 immunofluorescence, 1:80 dilution), we examined associations of ANA with reported sunscreen use when in the sun for 1 h or more. Logistic regression was used to calculate covariate-adjusted prevalence odds ratios (POR) and 95 % Confidence Intervals (CI), overall and stratified by demographic factors, season, and vitamin D. We explored associations and joint effects with other sun protective behaviors and sunburn in the past 12 months.

RESULTS

The association of ANA with sunscreen differed by age (interaction p = 0.004): for ages 20-39, we saw an exposure response (POR 2.61, 95 % CI 1.50, 4.24 for using sunscreen always or most of the time, and POR 1.85; 1.12, 3.05 for less frequent versus never-use; trend p < 0.001). These associations were more apparent in females (interaction p = 0.082), non-Hispanic white and black participants (vs. other race/ethnicity, interaction p = 0.023), and those with sufficient serum vitamin D (≥50 vs. <50 nmol/L, interaction p = 0.001). ANA was not associated with other protective behaviors and not confounded or modified by these behaviors or recent sunburn.

CONCLUSIONS

These cross-sectional findings showed frequent sunscreen was associated with ANA in younger adults, supporting the need for replication, and longitudinal studies with detailed exposure histories.

How Do ROS Induce NETosis? Oxidative DNA Damage, DNA Repair, and Chromatin Decondensation

Neutrophil extracellular traps (NETs) are intricate, DNA-based, web-like structures adorned with cytotoxic proteins. They play a crucial role in antimicrobial defense but are also implicated in autoimmune diseases and tissue injury. The process of NET formation, known as NETosis, is a regulated cell death mechanism that involves the release of these structures and is unique to neutrophils. NETosis is heavily dependent on the production of reactive oxygen species (ROS), which can be generated either through NADPH oxidase (NOX) or mitochondrial pathways, leading to NOX-dependent or NOX-independent NETosis, respectively. Recent research has revealed an intricate interplay between ROS production, DNA repair, and NET formation in different contexts. UV radiation can trigger a combined process of NETosis and apoptosis, known as apoNETosis, driven by mitochondrial ROS and DNA repair. Similarly, in calcium ionophore-induced NETosis, both ROS and DNA repair are key components, but only play a partial role. In the case of bacterial infections, the early stages of DNA repair are pivotal. Interestingly, in serum-free conditions, spontaneous NETosis occurs through NOX-derived ROS, with early-stage DNA repair inhibition halting the process, while late-stage inhibition increases it. The intricate balance between DNA repair processes and ROS production appears to be a critical factor in regulating NET formation, with different pathways being activated depending on the nature of the stimulus. These findings not only deepen our understanding of the mechanisms behind NETosis but also suggest potential therapeutic targets for conditions where NETs contribute to disease pathology.

[Immunopathogenesis of systemic lupus erythematosus]

Insights into the immunopathogenesis of systemic lupus erythematosus (SLE) help to understand the complex disease patterns and to develop new treatment strategies. The disease manifestations essentially result from autoantibodies, immune complexes and cytokines. Particularly the propensity towards developing various autoantibodies is central to the disease itself; autoantibody specificities lead to highly variable organ manifestations. This review article delineates the clinically relevant state of knowledge on SLE pathogenesis, with the goal to establish a model useful for clinical practice, which also helps to classify the novel therapeutic approaches.

Montelukast as a treatment for refractory cutaneous lupus: A case series

INTRODUCTION

There are no drugs specifically approved to treat cutaneous lupus. Inflammatory cells in lupus skin lesions can produce leukotrienes (LT), which promote tissue damage. In addition to hypersensitivity reactions, LT are also associated with cardiovascular diseases and elevated serum LT levels have been linked to worse atherosclerotic disease in lupus. Targeting LT could thus be an alternative to treat lupus. We present 4 cases of cutaneous lupus successfully treated with montelukast (MLK), a Cys-LT antagonist.

METHODS

Four consecutive female systemic lupus erythematosus (SLE) patients with refractory skin lesions were treated with MLK (10 mg/d) in the Hospital Universitário Walter Cantídio of the Universidade Federal do Ceará. Skin lesions were scored using Revised Cutaneous LE Disease Area and Severity Index (RCLASI). Relative expression of the 5-lipoxigenase (ALOX5) and 15-lipoxigenase (ALOX15) genes was determined in peripheral blood cells (PBC) from lupus patients and 4 age-matched female controls.

RESULTS

All patients experienced improvement of skin lesions measured using RCLASI scores within 2-12 weeks following initiation of MLK. The response was sustained for at least 3 months follow-up and no adverse events were recorded. ALOX5 but not ALOX15 gene expression was significantly (P = 0.0425) increased in PBC from SLE patients vs controls.

CONCLUSION

This is the first report of a fast and sustained successful response of cutaneous lupus to MLK. Given its acceptable safety profile, our data encourage development of a randomized trial as an attempt to reposition MLK as a safe, affordable alternative to treat cutaneous lupus.

Interferons and systemic lupus erythematosus: Pathogenesis, clinical features, and treatments in interferon-driven disease

Type I interferons (IFNs) have recently received a lot of attention with the elucidation of the pathogenesis of systemic lupus erythematosus (SLE). Type I IFNs are associated with many SLE symptoms and play a role in the pathogenesis of autoimmune diseases that may occur concurrently with SLE, such as Sjögren's syndrome, antiphospholipid syndrome, myositis, scleroderma, and interferonopathy. Type I IFNs could be the link between these diseases. However, direct measurement of type I IFN levels and the IFN gene signature is currently unavailable in clinical practice. This review discusses type I IFN signalling in SLE, investigates the role of type I IFN in the clinical manifestations and symptoms associated with SLE and other IFN-related diseases, and discusses the clinical tests that can be used to diagnose SLE and measure disease activity. In addition, the role of type I IFN-blocking therapies as potential treatments for SLE is discussed.

Mitochondrial ROS and base excision repair steps leading to DNA nick formation drive ultraviolet induced-NETosis

Reactive oxygen species (ROS) is essential for neutrophil extracellular trap formation (NETosis), and generated either by NADPH oxidases (e.g., during infections) or mitochondria (e.g., sterile injury) in neutrophils. We recently showed that ultraviolet (UV) radiation, a sterile injury-inducing agent, dose-dependently induced mitochondrial ROS generation, and increasing levels of ROS shifted the neutrophil death from apoptosis to NETosis. Nevertheless, how ROS executes UV-induced NETosis is unknown. In this study, we first confirmed that UV doses used in our experiments generated mitochondrial ROS, and the inhibition of mitochondrial ROS suppressed NETosis (Mitosox, SYTOX, immunocytochemistry, imaging). Next, we showed that UV irradiation extensively oxidized DNA, by confocal imaging of 8-oxyguanine (8-oxoG) in NETs. Immunofluorescence microscopy further showed that a DNA repair protein, proliferating cell nuclear antigen, was widely distributed throughout the DNA, indicating that the DNA repair machinery was active throughout the genome during UV-induced NETosis. Inhibition of specific steps of base excision repair (BER) pathway showed that steps leading up to DNA nick formation, but not the later steps, suppressed UV-induced NETosis. In summary, this study shows that (i) high levels of mitochondrial ROS produced following UV irradiation induces extensive oxidative DNA damage, and (ii) early steps of the BER pathway leading to DNA nicking results in chromatin decondensation and NETosis. Collectively, these findings reveal how ROS induces NOX-independent NETosis, and also a novel biological mechanism for UV irradiation- and -mitochondrial ROS-mediated NETosis.

Cutaneous lupus erythematosus: a review of etiopathogenic, clinical, diagnostic and therapeutic aspects

Cutaneous lupus erythematosus is an autoimmune disease of varied clinical expression, which may present as an exclusively cutaneous disease or be one of the multiple manifestations of systemic lupus erythematosus. Its classification includes acute, subacute, intermittent, chronic and bullous subtypes, which are usually identified based on clinical features and histopathological and laboratory findings. Other non-specific cutaneous manifestations may be associated with systemic lupus erythematosus and are usually related to disease activity. Environmental, genetic and immunological factors play a role in the pathogenesis of skin lesions in lupus erythematosus. Recently, considerable progress has been made in elucidating the mechanisms involved in their development, which allows for foreseeing future targets for more effective treatments. This review proposes to discuss the main etiopathogenic, clinical, diagnostic and therapeutic aspects of cutaneous lupus erythematosus, aiming to update internists and specialists from different areas.

Chlorogenic Acid Relieves the Lupus Erythematosus-like Skin Lesions and Arthritis in MRL/lpr Mice

Chlorogenic acid (CGA) is a phenylpropyl substance synthesized through the shikimic acid pathway. In addition to its anti-tumor, anti-inflammatory, and antioxidant abilities, CGA also has immunomodulatory effects. The aim of the present study is to investigate the therapeutic effects of CGA on the skin damage and arthritis caused by systemic lupus erythematosus (SLE) in an MRL/lpr mouse model. In the SLE model, female MRL/lpr mice at the age of 10 weeks old were treated with CGA daily or cyclophosphamide (CTX) weekly via intraperitoneal injection for three months. After treatment, CGA can significantly alleviate the skin and mucous membrane damage caused by SLE and has a certain improvement effect on arthritis. CGA could inhibit dsDNA expression to a certain extent but has no obvious regulation on ANA concentration. The ELISA and BioMAP results indicated that CGA might play an anti-inflammatory role by down-regulating the interleukin (IL)-17 level. In conclusion, our study demonstrates that CGA can alleviate multiorgan damage in MRL/lpr mice by reducing IL-17.

Targeting of EIF4EBP1 by miR-99a-3p affects the functions of B lymphocytes via autophagy and aggravates SLE disease progression

Excessive activation of immune cells plays a key role in the pathogenesis of systemic lupus erythematosus (SLE). The regulation of immune cells by miRNAs is a research hotspot. In this study, second-generation high-throughput sequencing revealed a reduction in miR-99a-3p expression in patients with SLE; however, the specific mechanism underlying this phenomenon remains unclear. After transfection with an miR-99a-3p agomir, the proliferation of Ball-1 cells decreased and the levels of their apoptosis increased. The opposite effects were observed in cells transfected with the miR-99a-3p antagomir. Luciferase reporter assay indicated that miR-99a-3p directly targeted EIF4EBP1. Rescue experiments confirmed the proposed interaction between miR-99a-3p and EIF4EBP1. In vitro, in vivo and clinical investigations further confirmed that the miR-99a-3p agomir reduced the expression of EIF4EBP1, LC3B and LAMP-2A. In the in vivo experiments, serum levels of anti-nuclear antibodies, double-stranded DNA, IgE, IgM, IL-6, IL-10 and B lymphocyte stimulator were higher in mice from the antagomir group than those in mice from the MRL/lpr group. Furthermore, the protein and mRNA levels of EIF4EBP1, LC3B and LAMP-2A, the intensity of immunohistochemical staining of EIF4EBP1, LC3B and LAMP-2A, the urinary protein levels, and the C3 immunofluorescence deposition increased in mice from the antagomir group. The upregulation of miR-99a-3p expression protected B cells from EIF4EBP1-mediated autophagy, whilst the downregulation of miR-99a-3p expression induced autophagy via the EIF4EBP1-mediated regulation of the autophagy signalling pathway in B cells isolated from individuals with SLE. Based on these results, miR-99a-3p and EIF4EBP1 may be considered potential targets for SLE treatment.

The Pathogenesis, Molecular Mechanisms, and Therapeutic Potential of the Interferon Pathway in Systemic Lupus Erythematosus and Other Autoimmune Diseases

Therapeutic success in treating patients with systemic lupus erythematosus (SLE) is limited by the multivariate disease etiology, multi-organ presentation, systemic involvement, and complex immunopathogenesis. Agents targeting B-cell differentiation and survival are not efficacious for all patients, indicating a need to target other inflammatory mediators. One such target is the type I interferon pathway. Type I interferons upregulate interferon gene signatures and mediate critical antiviral responses. Dysregulated type I interferon signaling is detectable in many patients with SLE and other autoimmune diseases, and the extent of this dysregulation is associated with disease severity, making type I interferons therapeutically tangible targets. The recent approval of the type I interferon-blocking antibody, anifrolumab, by the US Food and Drug Administration for the treatment of patients with SLE demonstrates the value of targeting this pathway. Nevertheless, the interferon pathway has pleiotropic biology, with multiple cellular targets and signaling components that are incompletely understood. Deconvoluting the complexity of the type I interferon pathway and its intersection with lupus disease pathology will be valuable for further development of targeted SLE therapeutics. This review summarizes the immune mediators of the interferon pathway, its association with disease pathogenesis, and therapeutic modalities targeting the dysregulated interferon pathway.

Difference of IFI44L methylation and serum IFN-a1 level among patients with discoid and systemic lupus erythematosus and healthy individuals

Lupus erythematosus (LE) is an autoimmune disease that can be divided into two types. The cutaneous lupus erythematosus (CLE), such as discoid LE (DLE), affects only the skin. While the systemic lupus erythematosus (SLE) affects the hematopoietic, renal, and other systems. We previously found that IFI44L methylation could be a biomarker for SLE. Here, we detect the IFI44L methylation by high-resolution melting-quantitative polymerase chain reaction (HRM-qPCR) assay. The positive percentages of SLE, DLE and healthy controls (HC) are 96.00%, 27.45%, 2.00%, if the curve of 25% methylation was used as the threshold of SLE. And we determined the serum IFN-a1 level by enzyme-linked immunosorbent assay (ELISA) in SLE, DLE and HC. The serum concentration of IFN-a1 in patients with SLE was significantly higher than in the DLE (12.63 ​± ​6.38 ​pg/mL vs 7.99 ​± ​2.28 ​pg/mL, P ​< ​0.05) and HC (12.63 ​± ​6.38 ​pg/mL vs 7.17 ​± ​1.86 ​pg/mL, P ​< ​0.05). But the expression level of IFN-a1 in serum was not significantly different between DLE and HC (7.99 ​± ​2.28 ​pg/mL vs 7.17 ​± ​1.86 ​pg/mL, P ​= ​0.5365). This suggests that methylation of IFI44L and serum concentration of IFN-a1 may be used as biomarkers to distinguish DLE from SLE.