Molecular profiling and gene expression analysis in cutaneous sarcoidosis: the role of interleukin-12, interleukin-23, and the T-helper 17 pathway

Bioinformatic meta-analysis reveals novel differentially expressed genes and pathways in sarcoidosis

Introduction

Sarcoidosis is a multi-system inflammatory disease of unknown origin with heterogeneous clinical manifestations varying from a single organ non-caseating granuloma site to chronic systemic inflammation and fibrosis. Gene expression studies have suggested several genes and pathways implicated in the pathogenesis of sarcoidosis, however, due to differences in study design and variable statistical approaches, results were frequently not reproducible or concordant. Therefore, meta-analysis of sarcoidosis gene-expression datasets is of great importance to robustly establish differentially expressed genes and signalling pathways.

Methods

We performed meta-analysis on 22 published gene-expression studies on sarcoidosis. Datasets were analysed systematically using same statistical cut-offs. Differentially expressed genes were identified by pooling of p-values using Edgington's method and analysed for pathways using Ingenuity Pathway Analysis software.

Results

A consistent and significant signature of novel and well-known genes was identified, those collectively implicated both type I and type II interferon mediated signalling pathways in sarcoidosis. In silico functional analysis showed consistent downregulation of eukaryotic initiation factor 2 signalling, whereas cytokines like interferons and transcription factor STAT1 were upregulated. Furthermore, we analysed affected tissues to detect differentially expressed genes likely to be involved in granuloma biology. This revealed that matrix metallopeptidase 12 was exclusively upregulated in affected tissues, suggesting a crucial role in disease pathogenesis.

Discussion

Our analysis provides a concise gene signature in sarcoidosis and expands our knowledge about the pathogenesis. Our results are of importance to improve current diagnostic approaches and monitoring strategies as well as in the development of targeted therapeutics.

Cutaneous Sarcoidosis

Sarcoidosis is a multisystem disease that most commonly affects the lungs, lymphatic system, eyes, and skin but any organ may be involved. Cutaneous sarcoidosis most commonly presents as pink-red to red-brown papules and plaques that commonly affect the head and neck. With the skin being readily accessible for evaluation and biopsy, when sarcoidosis is suspected, dermatologic evaluation may be helpful for establishing a definitive diagnosis. Treatment strategy depends on the severity and distribution of skin lesions and should incorporate patient preference and treatment considerations for other organs that may be involved.

Increased circulating interleukin-23 level in patients with sarcoidosis

BACKGROUND

Sarcoidosis is a Th1-mediated chronic inflammatory disease characterized by non-caseating granulomas. Its pathogenesis is not yet clear, but the possible role of various proinflammatory cytokines is being discussed.

AIM

This study aims to determine serum cytokine (IL-6, IL-12, IL-17, and IL-23) levels in patients with sarcoidosis, and to determine a possible correlation with clinical and laboratory findings of the disease.

MATERIAL AND METHOD

Forty-four biopsy-proven sarcoidosis patients followed up at a single centre and 41 healthy volunteers were included in the study. Demographic, clinical, laboratory, and radiological data of all patients were recorded. Serum samples from the patients and the control group were taken and IL-6, IL-12, IL-17, IL-23 were measured by ELISA method.

RESULTS

Of the 44 sarcoidosis patients, 13(29.5%) were male and 31(70.5%) were female. Average patient age was 47.4 years, mean disease duration was 3.2 years. Twenty-one (47.7%) patients had erythema nodosum, three (6.8%) had uveitis, 40(90.9%) had arthralgia, 23(52.3%) had ankle arthritis, 15(34.1%) had enthesitis. Laboratory evaluation showed increased serum ACE levels in 24(54.5%) patients, increased serum calcium levels in 11 (25%) patients, increased serum D3 levels in 5(11.4%) patients, increased ESR and CRP levels in 22(50%) and 23(52.3%) patients, respectively. Compared with the control group higher serum IL-23 levels were found in the patients with sarcoidosis (p=.01). Serum IL-23 was associated with ankle arthritis (p=.02). Serum IL-6, IL-12, and IL-17 levels were similar in the sarcoidosis patients and the control group (p=.128, p=.212, p=.521 respectively).

CONCLUSION

In our study, we found increased serum IL-23 in patients with sarcoidosis, while serum IL-6, IL-12, and IL-17 were detected as normal. Although our results are somewhat contradictory to other studies in the literature, the question should still be whether sarcoidosis is a Th1/Th17 disease. Multicentre studies are needed in this regard.

Genetic predisposition to sarcoidosis

Sarcoidosis is a complex systemic disease with clinical heterogeneity based on varying phenotypes and natural history. The detailed etiology of sarcoidosis remains unknown, but genetic predisposition as well as environmental exposures play a significant role in disease pathogenesis. We performed a comprehensive review of germline genetic (DNA) and transcriptomic (RNA) studies of sarcoidosis, including both previous studies and more recent findings. In this review, we provide an assessment of the following: genetic variants in sarcoidosis susceptibility and phenotypes, ancestry- and sex-specific genetic variants in sarcoidosis, shared genetic architecture between sarcoidosis and other diseases, and gene-environment interactions in sarcoidosis. We also highlight the unmet needs in sarcoidosis genetic studies, including the pressing requirement to include diverse populations and have consistent definitions of phenotypes in the sarcoidosis research community to help advance the application of genetic predisposition to sarcoidosis disease risk and manifestations.

Molecularly Targeted Therapies for Inflammatory Cutaneous Granulomatous Disorders: A Review of the Evidence and Implications for Understanding Disease Pathogenesis

Inflammatory cutaneous granulomatous diseases, including granuloma annulare, cutaneous sarcoidosis, and necrobiosis lipoidica, are distinct diseases unified by the hallmark of macrophage accumulation and activation in the skin. There are currently no Food and Drug Administration-approved therapies for these conditions except prednisone and repository corticotropin injection for pulmonary sarcoidosis. Treatment of these diseases has generally been guided by low-quality evidence and may involve broadly immunomodulatory medications. Development of new treatments has in part been limited by an incomplete understanding of disease pathogenesis. Recently, there has been substantial progress in better understanding the molecular pathogenesis of these disorders, opening the door for therapeutic innovation. Likewise, reported outcomes of treatment with immunologically targeted therapies may offer insights into disease pathogenesis. In this systematic review, we summarize progress in deciphering the pathomechanisms of these disorders and discuss this in the context of emerging evidence on the use of molecularly targeted therapies in treatment of these diseases.

Symptomatic myopathies in sarcoidosis: disease spectrum and myxovirus resistance protein A expression

OBJECTIVES

Symptomatic myopathy in sarcoidosis patients is not always due to sarcoid myopathy (ScM). We investigated the clinical and pathological spectrum including myxovirus resistance protein A (MxA) expression among sarcoidosis patients.

METHODS

We reviewed the Mayo Clinic database (May 1980-December 2020) to identify sarcoidosis patients with myopathic symptoms and pathological evidence of myopathy.

RESULTS

Among 5885 sarcoidosis patients, 21 had symptomatic myopathy. Eight carried a diagnosis of sarcoidosis 5.5 years (median) prior to myopathy onset. Eleven patients had ScM. The remaining had non-sarcoid myopathies (five IBM, one immune-mediated necrotizing myopathy, one non-specific myositis, two non-specific myopathy and one steroid myopathy). Estimated frequency of IBM is 85 per 100 000 sarcoidosis patients. The following features were associated with non-sarcoid myopathies (P < 0.05): (i) predominant finger flexor and quadriceps weakness, (ii) modified Rankin scale (mRS) >2 at time of diagnosis, (iii) creatine kinase >500 U/l, and (iv) absence of intramuscular granulomas. Sarcoplasmic MxA expression was observed in scattered myofibres in three patients, two of whom were tested for DM-specific autoantibodies and were negative. Immunosuppressive therapy led to improvement in mRS ≥1 in 5/10 ScM, none of the five IBM, and 3/3 remaining patients with non-sarcoid myopathies.

DISCUSSION

Symptomatic myopathy occurred in 0.36% of sarcoidosis. IBM was the second most common cause of myopathies after ScM. Frequency of IBM in sarcoidosis is higher than in the general population. Recognition of features suggestive of alternative aetiologies can guide proper treatment. Our findings of abnormal MxA expression warrant a larger study.

Macrophage Biology in Human Granulomatous Skin Inflammation

Cutaneous granulomatoses represent a heterogeneous group of diseases, which are defined by macrophage infiltration in the skin. Skin granuloma can be formed in the context of infectious and non-infectious conditions. Recent technological advances have deepened our understanding of the pathophysiology of granulomatous skin inflammation, and they provide novel insights into human tissue macrophage biology at the site of ongoing disease. Here, we discuss findings on macrophage immune function and metabolism derived from three prototypic cutaneous granulomatoses: granuloma annulare, sarcoidosis, and leprosy.

A transcriptomics-based meta-analysis identifies a cross-tissue signature for sarcoidosis

Sarcoidosis is a granulomatous disease of unknown etiology, immunologically characterized by a Th1 immune response. Transcriptome-wide expression studies in various types of sarcoid tissues contributed to better understanding of disease mechanisms. We performed a systematic database search on Gene Expression Omnibus (GEO) and utilized transcriptomic data from blood and sarcoidosis-affected tissues in a meta-analysis to identify a cross-tissue, cross-platform signature. Datasets were further separated into training and testing sets for development of a diagnostic classifier for sarcoidosis. A total of 690 differentially expressed genes were identified in the analysis among various tissues. 29 of the genes were robustly associated with sarcoidosis in the meta-analysis both in blood and in lung-associated tissues. Top genes included LINC01278 (P = 3.11 × 10^–13), GBP5 (P = 5.56 × 10^–07), and PSMB9 (P = 1.11 × 10^–06). Pathway enrichment analysis revealed activated IFN-γ, IL-1, and IL-18, autophagy, and viral infection response. IL-17 was observed to be enriched in peripheral blood specific signature genes. A 16-gene classifier achieved excellent performance in the independent validation data (AUC 0.711–0.964). This study provides a cross-tissue meta-analysis for expression profiles of sarcoidosis and identifies a diagnostic classifier that potentially can complement more invasive procedures.

From IL-17 to IFN-γ in inflammatory skin disorders: Is transdifferentiation a potential treatment target?

The targeted inhibition of effector cytokines such as interleukin 17 (IL-17) in psoriasis and IL-13 in atopic dermatitis offers impressive efficacy with a favorable side effect profile. In contrast, the downregulation of interferon gamma (IFN-γ) in T helper (Th) 1-dominant skin disorders may lead to more adverse events, given the crucial role of IFN-γ in antiviral and antitumoral immunity. Modulating Th17 and Th2 cell differentiation is performed by blocking IL-23 and IL-4, respectively, whereas anti-IL-12 antibodies are only moderately effective in downregulating Th1 lymphocyte differentiation. Therefore, a targeted approach of IFN-γ-driven disorders remains challenging. Recent literature suggests that certain pathogenic Th17 cell subsets with Th1 characteristics, such as CD4+CD161+CCR6+CXCR3+IL-17+IFN-y+ (Th17.1) and CD4+CD161+CCR6+CXCR3+IL-17-IFN-y+ (exTh17), are important contributors in Th1-mediated autoimmunity. Differentiation to a Th17.1 or exTh17 profile results in the upregulation of IFN-y. Remarkably, these pathogenic Th17 cell subsets are resistant to glucocorticoid therapy and the dampening effect of regulatory T cells (Treg). The identification of Th17.1/exTh17 cells in auto-immune disorders may explain the frequent treatment failure of conventional immunosuppressants. In this review, we summarize the current evidence regarding the cellular plasticity of Th17 cells in inflammatory skin disorders. A deeper understanding of this phenomenon may lead to better insights into the pathogenesis of various skin diseases and the discovery of a potential new treatment target.

[Acute sarcoid myopathy and neuropathy aggravated by ustekinumab administration in an elderly woman with psoriasis and systemic sarcoidosis]

A 72-year old woman, who had a history of psoriasis and psoriatic arthritis from age of 69, was admitted because of acute progression of dyspnea and generalized muscle weakness after initiation of ustekinumab. She had been diagnosed as having lung and eye sarcoidosis ten months before admission. Nerve conduction studies revealed multiple mononeuropathy and needle electromyography showed myogenic changes with spontaneous activities. Muscle pathology showed non-caseating epithelioid granuloma and high expression of HLA-class I in myofibers. Diagnosis of sarcoid myopathy and neuropathy aggravated by ustekinumab was made, and ustekinumab administration was discontinued, resulting in slight improvement of her respiratory and neuro-muscular symptoms, but her symptoms remained severely disabled. Treatment with oral steroids further improved her clinical symptoms and she became able to walk independently. We considered that ustekinumab inhibited IL-12 and IL-23 signaling, which caused an imbalance in Th1/Th17 differentiation and activation of Th1 cell differentiation, thereby promoting the development of sarcoid myopathy and neuropathy.

Inhibition of type 1 immunity with tofacitinib is associated with marked improvement in longstanding sarcoidosis

Sarcoidosis is an idiopathic inflammatory disorder that is commonly treated with glucocorticoids. An imprecise understanding of the immunologic changes underlying sarcoidosis has limited therapeutic progress. Here in this open-label trial (NCT03910543), 10 patients with cutaneous sarcoidosis are treated with tofacitinib, a Janus kinase inhibitor. The primary outcome is the change in the cutaneous sarcoidosis activity and morphology instrument (CSAMI) activity score after 6 months of treatment. Secondary outcomes included change in internal organ involvement, molecular parameters, and safety. All patients experience improvement in their skin with 6 patients showing a complete response. Improvement in internal organ involvement is also observed. CD4⁺ T cell-derived IFN-γ is identified as a central cytokine mediator of macrophage activation in sarcoidosis. Additional type 1 cytokines produced by distinct cell types, including IL-6, IL-12, IL-15 and GM-CSF, also associate with pathogenesis. Suppression of the activity of these cytokines, especially IFN-γ, correlates with clinical improvement. Our results thus show that tofacitinib treatment is associated with improved sarcoidosis symptoms, and predominantly acts by inhibiting type 1 immunity.

Association of spondyloarthritis and sarcoidosis: A retrospective observational population-based matched cohort study

OBJECTIVES

To investigate the association between spondyloarthritis (SpA) and sarcoidosis.

METHODS

An observational retrospective population-based matched cohort study was conducted. Using data from the Spanish Minimum Basic Data Set. All the admissions of patients with SpA reported between 1999 and 2015 were analysed and a control group matched by age, sex and year of admission was selected. Crude and age- and sex-adjusted incidence rates for sarcoidosis were calculated. Generalized linear models were used for trend analysis and unconditional logistic regression models for calculating crude and adjusted odds ratios (ORs) to assess the association between sarcoidosis and SpA.

RESULTS

The study database contained data on 214,280 hospitalisations: 107,140 admissions of patients with SpA and 107,140 of patients without SpA. Overall, 220 of the admissions were of patients with sarcoidosis: 133 (0.12%) in the SpA group and 87 (0.08%) in the non-SpA group (P<0.05). The incidence rates of sarcoidosis were 2.68 and 1.64 per 100,000 per year in the SpA and non-SpA groups, respectively. The trend was similar in the two cohorts. Regarding potential associations between SpA and sarcoidosis, the crude and adjusted ORs were 1.52 (95% CI: 1.16-2.01) and 1.50 (95% CI: 1.14-1.97) overall in patients with SpA, with adjusted ORs of 1.42 (95% CI: 1.03-1.94) and 1.81 (95% CI: 1.29-2.55) in patients with ankylosing spondylitis and psoriatic arthritis, respectively.

CONCLUSIONS

There is a relationship that is not due to chance between sarcoidosis and SpA and specifically that sarcoidosis is significantly associated with ankylosing spondylitis and psoriatic arthritis.

A new paradigm for leprosy diagnosis based on host gene expression

Transcriptional profiling is a powerful tool to investigate and detect human diseases. In this study, we used bulk RNA-sequencing (RNA-Seq) to compare the transcriptomes in skin lesions of leprosy patients or controls affected by other dermal conditions such as granuloma annulare, a confounder for paucibacillary leprosy. We identified five genes capable of accurately distinguishing multibacillary and paucibacillary leprosy from other skin conditions. Indoleamine 2,3-dioxygenase 1 (IDO1) expression alone was highly discriminatory, followed by TLR10, BLK, CD38, and SLAMF7, whereas the HS3ST2 and CD40LG mRNA separated multi- and paucibacillary leprosy. Finally, from the main differentially expressed genes (DEG) and enriched pathways, we conclude that paucibacillary disease is characterized by epithelioid transformation and granuloma formation, with an exacerbated cellular immune response, while multibacillary leprosy features epithelial-mesenchymal transition with phagocytic and lipid biogenesis patterns in the skin. These findings will help catalyze the development of better diagnostic tools and potential host-based therapeutic interventions. Finally, our data may help elucidate host-pathogen interplay driving disease clinical manifestations.

A Primer on the Clinical Aspects of Sarcoidosis for the Basic and Translational Scientist

The immunopathogenesis of sarcoidosis remains unclear. This failure in understanding has been clinically impactful, as it has impeded the accurate diagnosis, treatment, and prevention of this disease. Unraveling the mechanisms of sarcoidosis will require input from basic and translational scientists. In order to reach this goal, scientists must have a firm grasp of the clinical aspects of the disease, including its diagnostic criteria, the immunologic defects, clinical presentations, response to therapy, risk factors, and clinical course. This manuscript will provide an overview of the clinical aspects of sarcoidosis that are particularly relevant for the basic and translational scientist. The variable phenotypic expression of the disease will be described, which may be integral in identifying immunologic disease mechanisms that may be relevant to subgroups of sarcoidosis patients. Data concerning treatment and risk factors may yield important insights concerning germane immunologic pathways involved in the development of disease. It is hoped that this manuscript will stimulate communication between scientists and clinicians that will eventually lead to improved care of sarcoidosis patients.

Emerging Molecular Targets for the Treatment of Refractory Sarcoidosis

Sarcoidosis is a multisystem granulomatous disease of unknown origin that has variable clinical course and can affect nearly any organ. It has a chronic course in about 25% of patients. Corticosteroids (CS) are the cornerstone of therapy but their long-term use is associated with cumulative toxicity. Commonly used CS-sparing agents include methotrexate, cyclophosphamide, azathioprine, and mycophenolate mofetil. Twenty to forty percentage of sarcoidosis patients are refractory to these therapies or develop severe adverse events. Therefore, additional and targeted CS-sparing agents are needed for chronic sarcoidosis. Macrophage activation, interferon response, and formation of the granuloma are mainly mediated by T helper-1 responses. Different pro-inflammatory cytokines such as interleukin (IL)-8, IL-12, IL-6, and tumor necrosis factor-alpha (TNF-α) have been shown to be highly expressed in sarcoidosis-affected tissues. As a result of increased production of these cytokines, Janus kinase-signal transducer and activator of transcription (JAK-STAT) signaling is constitutively active in sarcoidosis. Several studies of biological agents that target TNF-α have reported their efficacy and appear today as a second line option in refractory sarcoidosis. Some case series report a positive effect of tocilizumab an anti-IL-6 monoclonal antibody in this setting. More recently, JAK inhibition appears as a new promising strategy. This review highlights key advances on the management of chronic refractory sarcoidosis. Novel therapeutic strategies and treatment agents to manage the disease are described.

Application of Proteomics in Sarcoidosis

Sarcoidosis is a multisystem disease with heterogeneity in manifestations and outcomes. System-level studies leveraging "omics" technologies are expected to define mechanisms contributing to sarcoidosis heterogeneous manifestations and course. With improvements in mass spectrometry (MS) and bioinformatics, it is possible to study protein abundance for a large number of proteins simultaneously. Contemporary fast-scanning MS enables the acquisition of spectral data for deep coverage of the proteins with data-dependent or data-independent acquisition MS modes. Studies leveraging MS-based proteomics in sarcoidosis have characterized BAL fluid (BALF), alveolar macrophages, plasma, and exosomes. These studies identified several differentially expressed proteins, including protocadherin-2 precursor, annexin A2, pulmonary surfactant A2, complement factors C3, vitamin-D-binding protein, cystatin B, and amyloid P, comparing subjects with sarcoidosis with control subjects. Other studies identified ceruloplasmin, complement factors B, C3, and 1, and others with differential abundance in sarcoidosis compared with other interstitial lung diseases. Using quantitative proteomics, most recent studies found differences in PI3K/Akt/mTOR, MAP kinase, pluripotency-associated transcriptional factor, and hypoxia response pathways. Other studies identified increased clathrin-mediated endocytosis and Fcγ receptor-mediated phagocytosis pathways in sarcoidosis alveolar macrophages. Although studies in mixed BAL and blood cells or plasma are limited, some of the changes in lung compartment are detected in the blood cells and plasma. We review proteomics for sarcoidosis with a focus on the existing MS data acquisition strategies, bioinformatics for spectral data analysis to infer protein identity and quantity, unique aspects about biospecimen collection and processing for lung-related proteomics, and proteomics studies conducted to date in sarcoidosis.

Gene Co-expression Networks Identifies Common Hub Genes Between Cutaneous Sarcoidosis and Discoid Lupus Erythematosus

In this study we analyzed gene co-expression networks of three immune-related skin diseases: cutaneous sarcoidosis (CS), discoid lupus erythematosus (DLE), and psoriasis. We propose that investigation of gene co-expression networks may provide insights into underlying disease mechanisms. Microarray expression data from two cohorts of patients with CS, DLE, or psoriasis skin lesions were analyzed. We applied weighted gene correlation network analysis (WGCNA) to construct gene-gene similarity networks and cluster genes into modules based on similar expression profiles. A module of interest that was preserved between datasets and corresponded with case/control status was identified. This module was related to immune activation, specifically leukocyte activation, and was significantly increased in both CS lesions and DLE lesions compared to their respective controls. Protein-protein interaction (PPI) networks constructed for this module revealed seven common hub genes between CS lesions and DLE lesions: TLR1, ITGAL, TNFRSF1B, CD86, SPI1, BTK, and IL10RA. Common hub genes were highly upregulated in CS lesions and DLE lesions compared to their respective controls in a differential expression analysis. Our results indicate common gene expression patterns in the immune processes of CS and DLE, which may have indications for future therapeutic targets and serve as Th1-mediated disease biomarkers. Additionally, we identified hub genes unique to CS and DLE, which can help differentiate these diseases from one another and may serve as unique therapeutic targets and biomarkers. Notably, we find common gene expression patterns in the immune processes of CS and DLE through utilization of WGCNA.

Molecular profiling in sarcoidosis

PURPOSE OF REVIEW

Sarcoidosis is a systemic disease characterized by granulomatous inflammation of unknown cause. There is extensive heterogeneity between patients with respect to the number and types of organs involved, disease course, and response to therapy. Recent research in the field has leveraged 'omics' techniques such as transcriptomics to identify important 'molecular profiles' in the disease. These tools may help in identifying clinically useful biomarkers and targets for therapy.

RECENT FINDINGS

Several studies have used gene expression profiling of predesignated lists or the entire genome to find genes and markers that differentiate sarcoidosis from healthy controls, but only a few have compared sarcoidosis patients based on disease phenotypes and organ involvement. The common gene pathways that have been repeatedly identified include those related to the interferon response, T-cell receptor signaling, and the major histocompatibility complex.

SUMMARY

While the molecular profiling studies to date offer the ability to compare sarcoidosis and health as well as across tissues, further longitudinal studies that include sarcoidosis patients with varying outcomes with respect to organ involvement and response to treatment are needed to identify clinically important phenotypes in the disease that can then be differentiated based on molecular features.

Recent advances in sarcoidosis genomics: epigenetics, gene expression, and gene by environment (G × E) interaction studies

PURPOSE OF REVIEW

We aim to review the most recent findings in genomics of sarcoidosis and highlight the gaps in the field.

RECENT FINDINGS

Original explorations of sarcoidosis subphenotypes, including cases associated with the World Trade Center and ocular sarcoidosis, have identified novel risk loci. Innovative gene--environment interaction studies utilizing modern analytical techniques have discovered risk loci associated with smoking and insecticide exposure. The application of whole-exome sequencing has identified genetic variants associated with persistent sarcoidosis and rare functional variations. A single epigenomics study has provided background knowledge of DNA methylation mechanisms in comparison with gene expression data. The application of machine-learning techniques has suggested new drug repositioning for the treatment of sarcoidosis. Several gene expression studies have identified prominent inflammatory pathways enriched in the affected tissue.

SUMMARY

Certainly, sarcoidosis research has recently advanced in the exploration of disease subphenotypes, utilizing novel analytical techniques, and including measures of clinical variation. Nevertheless, large-scale and diverse cohorts investigated with advanced sequencing methods, such as whole-genome and single-cell RNA sequencing, epigenomics, and meta-analysis coupled with cutting-edge analytic approaches, when employed, will broaden and translate genomics findings into clinical applications, and ultimately open venues for personalized medicine.

Psoriasis and Connective Tissue Diseases

Psoriasis is a chronic systemic inflammatory disease with various co-morbidities, having been recently considered as a comprehensive disease named psoriatic disease or psoriatic syndrome. Autoimmune diseases are one form of its co-morbidities. In addition to the genetic background, shared pathogenesis including innate immunity, neutrophil extracellular trap (NETs), and type I interferon, as well as acquitted immunity such as T helper-17 (Th17) related cytokines are speculated to play a significant role in both psoriasis and connective tissue diseases. On the other hand, there are definite differences between psoriasis and connective tissue diseases, such as their pathomechanisms and response to drugs. Therefore, we cannot expect that one stone kills two birds, and thus caution is necessary when considering whether the administered drug for one disease is effective or not for another disease. In this review, several connective tissue diseases and related diseases are discussed from the viewpoint of their coexistence with psoriasis.

Clinical Presentations, Pathogenesis, and Therapy of Sarcoidosis: State of the Art

Sarcoidosis is a systemic disease of unknown etiology characterized by the presence of noncaseating granulomas that can occur in any organ, most commonly the lungs. Early and accurate diagnosis of sarcoidosis remains challenging because initial presentations may vary, many patients are asymptomatic, and there is no single reliable diagnostic test. Prognosis is variable and depends on epidemiologic factors, mode of onset, initial clinical course, and specific organ involvement. From a pathobiological standpoint, sarcoidosis represents an immune paradox, where an excessive spread of both the innate and the adaptive immune arms of the immune system is accompanied by a state of partial immune anergy. For all these reasons, the optimal treatment for sarcoidosis remains unclear, with corticosteroid therapy being the current gold standard for those patients with significantly symptomatic or progressive pulmonary disease or serious extrapulmonary disease. This review is a state of the art of clinical presentations and immunological features of sarcoidosis, and the current therapeutic approaches used to treat the disease.

Sarcoidosis and the mTOR, Rac1, and Autophagy Triad

Sarcoidosis is an enigmatic multisystem disease characterized by the development and accumulation of granulomas: a compact collection of macrophages that have differentiated into epithelioid cells and which are associated with T helper (Th)1 and Th17 cells. Although no single causative factor has been shown to underlie sarcoidosis in humans, its etiology has been related to microbial, environmental, and genetic factors. We examine how these factors play a role in sarcoidosis pathogenesis. Specifically, we propose that dysfunction of mTOR, Rac1, and autophagy-related pathways not only hampers pathogen or nonorganic particle clearance but also participates in T cell and macrophage dysfunction, driving granuloma formation. This concept opens new avenues for potentially treating sarcoidosis and may serve as a blueprint for other granulomatous disorders.

New advances in the management of pulmonary sarcoidosis

Sarcoidosis is a highly variable granulomatous multisystem syndrome. It affects individuals in the prime years of life; both the frequency and severity of sarcoidosis are greater in economically disadvantaged populations. The diagnosis, assessment, and management of pulmonary sarcoidosis have evolved as new technologies and therapies have been adopted. Transbronchial needle aspiration guided by endobronchial ultrasound has replaced mediastinoscopy in many centers. Advanced imaging modalities, such as fluorodeoxyglucose positron emission tomography scanning, and the widespread availability of magnetic resonance imaging have led to more sensitive assessment of organ involvement and disease activity. Although several new insights about the pathogenesis of sarcoidosis exist, no new therapies have been specifically developed for use in the disease. The current or proposed use of immunosuppressive medications for sarcoidosis has been extrapolated from other disease states; various novel pathways are currently under investigation as therapeutic targets. Coupled with the growing recognition of corticosteroid toxicities for managing sarcoidosis, the use of corticosteroid sparing anti-sarcoidosis medications is likely to increase. Besides treatment of granulomatous inflammation, recognition and management of the non-granulomatous complications of pulmonary sarcoidosis are needed for optimal outcomes in patients with advanced disease.

Exploring the dynamic changes between pulmonary and cutaneous sarcoidosis based on gene expression

Sarcoidosis is a disease involving the growth of abnormal inflammatory granulomas and affecting multisystems. It has an unknown etiology. The lung and the skin are the most commonly involved organs. Although large amounts of research have focused on the pathogenesis of sarcoidosis, little is known about the link between cutaneous sarcoidosis and pulmonary sarcoidosis. Moreover, the gene expression profiles provide a novel way to find diagnostic or prognostic biomarkers. Therefore, the aim of this study was to analyze the differentially expressed genes (DEGs) in pulmonary sarcoidosis and cutaneous sarcoidosis patients and to compare them to healthy individuals. DEGs and their biological functions are dynamically dysregulated, and several common disease-related genes and mutual disease progression-related genes were identified which linked pulmonary sarcoidosis and cutaneous sarcoidosis together. The biological functional pathways regulated by these DEGs may allow to define the common mechanism shared by different type of sarcoidosis, providing novel insight into the common pathogenesis of sarcoidosis and opening the way to the development of new therapeutic strategies.

Cutaneous Granulomatosis: a Comprehensive Review

Cutaneous granulomatosis is a heterogeneous group of diseases, characterized by a skin inflammatory reaction triggered by a wide variety of stimuli, including infections, foreign bodies, malignancy, metabolites, and chemicals. From a pathogenic point of view, they are divided into non-infectious and infectious granulomas. Pathophysiological mechanisms are still poorly understood. Non-infectious granulomatous skin diseases include granuloma annulare, necrobiosis lipoidica, rheumatic nodules, foreign body granulomas, cutaneous sarcoidosis, and interstitial granulomatous dermatitis. Necrobiosis lipoidica is more frequent in diabetic patients. Infectious granulomas of the skin are caused by mycobacteria, in particular Mycobacterium tuberculosis or atypical mycobacteria; parasites, such as Leishmania; or fungi. Pathogenic mechanisms of M. tuberculosis-related granuloma are discussed. From a clinical point of view, it is useful to divide cutaneous granulomatosis into localized and more disseminated forms, although this distinction can be sometimes artificial. Three types of localized granulomatous lesions can be distinguished: palisaded granulomas (granuloma annulare, necrobiosis lipoidica, and rheumatoid nodules), foreign body granulomas, and infectious granulomas, which are generally associated with localized infections. Disseminated cutaneous granulomas can be divided into infectious, in particular tuberculosis, and non-infectious forms, among which sarcoidosis and interstitial granulomatous dermatitis. From a histological point of view, the common denominator is the presence of a granulomatous inflammatory infiltrate in the dermis and/or hypodermis; this infiltrate is mainly composed of macrophages grouped into nodules having a nodular, palisaded or interstitial architecture. Finally, we propose which diagnostic procedure should be performed when facing a patient with a suspected cutaneous granulomatosis.

Sarcoidosis Related Novel Candidate Genes Identified by Multi-Omics Integrative Analyses

Sarcoidosis is a multifactorial systemic disease characterized by granulomatous inflammation and greatly impacting on global public health. The etiology and mechanisms of sarcoidosis are not fully understood. Recent high-throughput biological research has generated vast amounts of multi-omics big data on sarcoidosis, but their significance remains to be determined. We sought to identify novel candidate regions, and genes consistently altered in heterogeneous omics studies so as to reveal the underlying molecular mechanisms. We conducted a comprehensive integrative literature analysis on global data on sarcoidosis, including genomic, transcriptomic, proteomic, and phenomic studies. We performed positional integration analysis of 38 eligible datasets originating from 17 different biological layers. Using the integration interval length of 50 kb, we identified 54 regions reaching significance value p ≤ 0.0001 and 15 regions with significance value p ≤ 0.00001, when applying more stringent criteria. Secondary literature analysis of the top 20 regions, with the most significant accumulation of signals, revealed several novel candidate genes for which associations with sarcoidosis have not yet been established, but have considerable support for their involvement based on omic data. These new plausible candidate genes include NELFE, CFB, EGFL7, AGPAT2, FKBPL, NRC3, and NEU1. Furthermore, annotated data were prepared to enable custom visualization and browsing of these sarcoidosis related omics evidence in the University of California Santa Cruz (UCSC) Genome Browser. Further multi-omics approaches are called for sarcoidosis biomarkers and diagnostic and therapeutic innovation. Our approach for harnessing multi-omics data and the findings presented herein reflect important steps toward understanding the etiology and underlying pathological mechanisms of sarcoidosis.

Transcriptome profiles in sarcoidosis and their potential role in disease prediction

PURPOSE OF REVIEW

Sarcoidosis is a systemic disease defined by the presence of nonnecrotizing granuloma in the absence of any known cause. Although the heterogeneity of sarcoidosis is well characterized clinically, the transcriptome of sarcoidosis and underlying molecular mechanisms are not. The signal of all transcripts, small and long noncoding RNAs, can be detected using microarrays or RNA-Sequencing. Analyzing the transcriptome of tissues that are directly affected by granulomas is of great importance to understand biology of the disease and may be predictive of disease and treatment outcome.

RECENT FINDINGS

Multiple genome wide expression studies performed on sarcoidosis affected tissues were published in the last 11 years. Published studies focused on differences in gene expression between sarcoidosis vs. control tissues, stable vs. progressive sarcoidosis, as well as sarcoidosis vs. other diseases. Strikingly, all these transcriptomics data confirm the key role of TH1 immune response in sarcoidosis and particularly of interferon-γ (IFN-γ) and type I IFN-driven signaling pathways.

SUMMARY

The steps toward transcriptomics of sarcoidosis in precision medicine highlight the potentials of this approach. Large prospective follow-up studies are required to identify signatures predictive of disease progression and outcome.

Increased T-helper 17.1 cells in sarcoidosis mediastinal lymph nodes

The lung-draining mediastinal lymph nodes (MLNs) are currently widely used to diagnose sarcoidosis. We previously reported that T-helper (Th) 17.1 cells are responsible for the exaggerated interferon-γ production in sarcoidosis lungs. In this study, we aimed to investigate 1) whether Th17.1 cells are also increased in the MLNs of sarcoidosis patients and 2) whether frequencies of the Th17.1 cells at diagnosis may correlate with disease progression.

MLN cells from treatment-naive pulmonary sarcoidosis patients (n=17) and healthy controls (n=22) and peripheral blood mononuclear cells (n=34) and bronchoalveolar lavage fluid (BALF) (n=36) from sarcoidosis patients were examined for CD4+ T-cell subset proportions using flow cytometry.

Higher proportions of Th17.1 cells were detected in sarcoidosis MLNs than in control MLNs. Higher Th17.1 cell proportions were found in sarcoidosis BALF compared with MLNs and peripheral blood. Furthermore, BALF Th17.1 cell proportions were significantly higher in patients developing chronic disease than in patients undergoing resolution within 2 years of clinical follow-up.

These data suggest that Th17.1 cell proportions in pulmonary sarcoidosis can be evaluated as a diagnostic and/or prognostic marker in clinical practice and could serve as a new therapeutic target.

T-cell immunology in sarcoidosis: Disruption of a delicate balance between helper and regulatory T-cells

PURPOSE OF REVIEW

Although the aetiology of sarcoidosis is not yet completely understood, immunological changes within the T-cell compartment are characteristic for an exaggerated antigen-driven immune response. In this review, we describe the most recent findings on T-cell subset responses and regulation in sarcoidosis. We discuss how future immunological research can advance the field to unravel pathobiological mechanisms of this intriguingly complex disease.

RECENT FINDINGS

Research into the field of T-cell plasticity has recently challenged the long-held T helper type 1 (Th1) paradigm in sarcoidosis and striking parallels with autoimmune disorders and common variable immunodeficiency were recognized. For instance, it was demonstrated that Th17.1-cells rather than Th1-cells are responsible for the exaggerated IFN-γ production in pulmonary sarcoidosis. Furthermore, impaired regulatory T-cell function and alterations within the expression of co-inhibitory receptors that control T-cell responses, such as PD-1, CTLA-4 and BTNL2, raise new questions regarding T-cell regulation in pulmonary sarcoidosis.

SUMMARY

It becomes increasingly clear that Th17(.1)-cells and regulatory T-cells are key players in sarcoidosis T-cell immunology. New findings on plasticity and co-inhibitory receptor expression by these subsets help build a more comprehensive model for T-cell regulation in sarcoidosis and will finally shed light on the potential of new treatment modalities.

New molecular targets for the treatment of sarcoidosis

PURPOSE OF REVIEW

Sarcoidosis is a chronic granulomatous disease typically affecting the lung, lymph nodes, and other organ systems. Evidence suggests that the morbidity and mortality rates for sarcoidosis in the USA are rising, despite widespread use of anti-inflammatory therapies. In this review, we survey new therapies that target specific inflammatory pathways in other diseases (such as rheumatoid arthritis, Crohn's disease, and psoriasis) that are similar to pathways relevant to sarcoidosis immunopathogenesis, and therefore, represent potentially new sarcoidosis therapies.

RECENT FINDINGS

Immunopathogenesis of sarcoidosis has been well elucidated over the past few years. There is abundant evidence for T-cell activation in sarcoidosis leading to activation of both Th1 and Th17 inflammatory cascades. Therapies targeting T-cell activation, Th1 pathways (such as the interleukin-6 inhibitors), Th17 pathway mediators, and others have been Food and Drug Administration approved or under investigation to treat a variety of autoimmune inflammatory diseases, but have not been studied in sarcoidosis. Targeting the p38 mitogen-activated protein kinases and the ubiquitine proteasome system with new agents may also represent a novel therapeutic option for patients with sarcoidosis.

SUMMARY

Rising morbidity and mortality rates for patients with sarcoidosis strongly support the need to develop more effective anti-inflammatory therapies to treat chronic disease.

High-Density Genetic Mapping Identifies New Susceptibility Variants in Sarcoidosis Phenotypes and Shows Genomic-driven Phenotypic Differences

RATIONALE

Sarcoidosis is a multisystem disease of unknown cause. Löfgren's syndrome (LS) is a characteristic subgroup of sarcoidosis that is associated with a good prognosis in sarcoidosis. However, little is known about its genetic architecture or its broader phenotype, non-LS sarcoidosis.

OBJECTIVES

To address the genetic architecture of sarcoidosis phenotypes, LS and non-LS.

METHODS

An association study in a white Swedish cohort of 384 LS, 664 non-LS, and 2,086 control subjects, totaling 3,134 subjects using a fine-mapping genotyping platform was conducted. Replication was performed in four independent cohorts, three of white European descent (Germany, n = 4,975; the Netherlands, n = 613; and Czech Republic, n = 521), and one of black African descent (United States, n = 1,657), totaling 7,766 subjects.

MEASUREMENTS AND MAIN RESULTS

A total of 727 LS-associated variants expanding throughout the extended major histocompatibility complex (MHC) region and 68 non-LS-associated variants located in the MHC class II region were identified and confirmed. A shared overlap between LS and non-LS defined by 17 variants located in the MHC class II region was found. Outside the MHC region, two LS-associated loci, in ADCY3 and between CSMD1 and MCPH1, were observed and replicated.

CONCLUSIONS

Comprehensive and integrative analyses of genetics, transcription, and pathway modeling on LS and non-LS indicates that these sarcoidosis phenotypes have different genetic susceptibility, genomic distributions, and cellular activities, suggesting distinct molecular mechanisms in pathways related to immune response with a common region.

Derivation of marker gene signatures from human skin and their use in the interpretation of the transcriptional changes associated with dermatological disorders

Numerous studies have explored the altered transcriptional landscape associated with skin diseases to understand the nature of these disorders. However, data interpretation represents a significant challenge due to a lack of good maker sets for many of the specialized cell types that make up this tissue, whose composition may fundamentally alter during disease. Here we have sought to derive expression signatures that define the various cell types and structures that make up human skin, and demonstrate how they can be used to aid the interpretation of transcriptomic data derived from this organ. Two large normal skin transcriptomic datasets were identified, one RNA-seq (n = 578), the other microarray (n = 165), quality controlled and subjected separately to network-based analyses to identify clusters of robustly co-expressed genes. The biological significance of these clusters was then assigned using a combination of bioinformatics analyses, literature, and expert review. After cross comparison between analyses, 20 gene signatures were defined. These included expression signatures for hair follicles, glands (sebaceous, sweat, apocrine), keratinocytes, melanocytes, endothelia, muscle, adipocytes, immune cells, and a number of pathway systems. Collectively, we have named this resource SkinSig. SkinSig was then used in the analysis of transcriptomic datasets for 18 skin conditions, providing in-context interpretation of these data. For instance, conventional analysis has shown there to be a decrease in keratinization and fatty metabolism with age; we more accurately define these changes to be due to loss of hair follicles and sebaceous glands. SkinSig also highlighted the over-/under-representation of various cell types in skin diseases, reflecting an influx in immune cells in inflammatory disorders and a relative reduction in other cell types. Overall, our analyses demonstrate the value of this new resource in defining the functional profile of skin cell types and appendages, and in improving the interpretation of disease data. © 2016 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of Pathological Society of Great Britain and Ireland.

Sarcoidosis extent relates to molecular variability

The molecular basis of sarcoidosis phenotype heterogeneity and its relationship to effective treatment of sarcoidosis have not been elucidated. Peripheral samples from sarcoidosis subjects who participated in a Phase II study of golimumab [anti-tumour necrosis factor (TNF)-α] and ustekinumab [anti-interleukin (IL)-12p40] were used to measure the whole blood transcriptome and levels of serum proteins. Differential gene and protein expression analyses were used to explore the molecular differences between sarcoidosis phenotypes as defined by extent of organ involvement. The same data were also used in conjunction with an enrichment algorithm to identify gene expression changes associated with treatment with study drugs compared to placebo. Our analyses revealed marked heterogeneity among the three sarcoidosis phenotypes included in the study cohort, including striking differences in enrichment of the interferon pathway. Conversely, enrichments of multiple pathways, including T cell receptor signalling, were similar among phenotypes. We also identify differences between treatment with golimumab and ustekinumab that may explain the differences in trends for clinical efficacy observed in the trial. We find that molecular heterogeneity is associated with sarcoidosis in a manner that may be related to the extent of organ involvement. These findings may help to explain the difficulty in identifying clinically efficacious sarcoidosis treatments and suggest hypotheses for improved therapeutic strategies.

What is new in the histogenesis of granulomatous skin diseases?

A granuloma is a form of inflammation, which predominantly consists of macrophages. It typically develops when the immune system attempts to enclose substances that are usually insoluble and cannot be eliminated to prevent the spread of these substances to the other body compartments. According to the source of the substances, granulomatous diseases can be divided into two groups: infectious and non-infectious. The mechanisms of infectious granuloma formation have been widely investigated because of its easy reproducibility in experimental models, both in vivo and in vitro. On the contrary, mechanisms of non-infectious granuloma formation have not been well investigated because of the difficulty to reproduce this formation in experimental models. In this article, we review our recent understanding of the histogenesis and pathogenesis of granuloma formation, confirmed from studies of infectious granulomas, and we present potential hypotheses of the histogenesis and pathogenesis of non-infectious granulomas based on clinical investigations.

Sarcoidosis activates diverse transcriptional programs in bronchoalveolar lavage cells

Background

Sarcoidosis is a multisystem immuno-inflammatory disorder of unknown etiology that most commonly involves the lungs. We hypothesized that an unbiased approach to identify pathways activated in bronchoalveolar lavage (BAL) cells can shed light on the pathogenesis of this complex disease.

Methods

We recruited 15 patients with various stages of sarcoidosis and 12 healthy controls. All subjects underwent bronchoscopy with lavage. For each subject, total RNA was extracted from BAL cells and hybridized to an Affymetrix U133A microarray. Rigorous statistical methods were applied to identify differential gene expression between subjects with sarcoidosis vs. controls. To better elucidate pathways differentially activated between these groups, we integrated network and gene set enrichment analyses of BAL cell transcriptional profiles.

Results

Sarcoidosis patients were either non-smokers or former smokers, all had lung involvement and only two were on systemic prednisone. Healthy controls were all non-smokers. Comparison of BAL cell gene expression between sarcoidosis and healthy subjects revealed over 1500 differentially expressed genes. Several previously described immune mediators, such as interferon gamma, were upregulated in the sarcoidosis subjects. Using an integrative computational approach we constructed a modular network of over 80 gene sets that were highly enriched in patients with sarcoidosis. Many of these pathways mapped to inflammatory and immune-related processes including adaptive immunity, T-cell signaling, graft vs. host disease, interleukin 12, 23 and 17 signaling. Additionally, we uncovered a close association between the proteasome machinery and adaptive immunity, highlighting a potentially important and targetable relationship in the pathobiology of sarcoidosis.

Conclusions

BAL cells in sarcoidosis are characterized by enrichment of distinct transcriptional programs involved in immunity and proteasomal processes. Our findings add to the growing evidence implicating alveolar resident immune effector cells in the pathogenesis of sarcoidosis and identify specific pathways whose activation may modulate disease progression.

Electronic supplementary material

The online version of this article (doi:10.1186/s12931-016-0411-y) contains supplementary material, which is available to authorized users.

Enhanced LPS-induced activation of IL-27 signalling in sarcoidosis

RATIONALE

Granulomas in sarcoidosis have recently been described as containing Interleukin (IL)-27, one of the members of the IL-12 family of cytokines, which also includes IL-35. Levels of these cytokines and the IL-27 receptor subunits were hypothesised to differ between patients with sarcoidosis compared to healthy controls in peripheral blood.

METHODS

Using a cross-sectional study design, plasma and peripheral blood mononuclear cells (PBMC) were collected from patients and control subjects. Protein and mRNA (in PBMC) levels for IL-27 and IL-35 (IL27, EBI3, IL12A subunits) as well as IL-27 receptor (IL6ST and IL27RA subunits) were assessed spontaneously and following direct (LPS) and indirect (anti-CD3/28 activation beads) macrophage stimulation using RT- PCR, ELISA and flow cytometry.

RESULTS

Following stimulation with LPS, PBMC of patients with sarcoidosis displayed significantly enhanced expression of IL27 and EBI3 mRNA (p = 0.020 and p = 0.037 respectively) compared to PBMCs from healthy controls. There was also significantly enhanced production of IL-27 by PBMC from patients with sarcoidosis compared to healthy controls in response to LPS stimulation (p = 0.027). IL6ST mRNA and IL6ST protein were significantly lower in patients with sarcoidosis (mRNA p = 0.0002; MFI p = 0.0015) whilst IL27RA protein levels were significantly higher in patients with sarcoidosis compared to healthy controls (MFI p < 0.0001). Plasma IL-35 protein levels did not differ between control and sarcoidosis subjects (p = 0.23).

CONCLUSION

These results suggest there may be exaggerated activation of IL-27 signalling in response to LPS in sarcoidosis.

Parallel Gene Expression Changes in Sarcoidosis Involving the Lacrimal Gland, Orbital Tissue, or Blood

IMPORTANCE

Sarcoidosis is a major cause of ocular or periocular inflammation. The pathogenesis of sarcoidosis is incompletely understood and diagnosis often requires a biopsy.

OBJECTIVE

To determine how gene expression in either orbital adipose tissue or the lacrimal gland affected by sarcoidosis compares with gene expression in other causes of orbital disease and how gene expression in tissue affected by sarcoidosis compares with gene expression in peripheral blood samples obtained from patients with sarcoidosis.

DESIGN, SETTING, AND PARTICIPANTS

In a multicenter, international, observational study, gene expression profiling of formalin-fixed biopsy specimens, using GeneChipp U133 Plus 2 microarrays (Affymetrix), was conducted between October 2012 and January 2014 on tissues biopsied from January 2000 through June 2013. Participants included 12 patients with orbital sarcoidosis (7 in adipose tissue; 5 affecting the lacrimal gland) as well as comparable tissue from 6 healthy individuals serving as controls or patients with thyroid eye disease, nonspecific orbital inflammation, or granulomatosis with polyangiitis. In addition, results were compared with gene expression in peripheral blood samples obtained from 12 historical individuals with sarcoidosis.

MAIN OUTCOMES AND MEASURES

Significantly differentially expressed transcripts defined as a minimum of a 1.5-fold increase or a comparable decrease and a false discovery rate of P < .05.

RESULTS

Signals from 2449 probe sets (transcripts from approximately 1522 genes) were significantly increased in the orbital adipose tissue from patients with sarcoidosis. Signals from 4050 probe sets (approximately 2619 genes) were significantly decreased. Signals from 3069 probe sets (approximately 2001 genes) were significantly higher and 3320 (approximately 2283 genes) were significantly lower in the lacrimal gland for patients with sarcoidosis. Ninety-two probe sets (approximately 69 genes) had significantly elevated signals and 67 probe sets (approximately 56 genes) had significantly lower signals in both orbital tissues and in peripheral blood from patients with sarcoidosis. The transcription factors, interferon-response factor 1, interferon-response factor 2, and nuclear factor κB, were strongly implicated in the expression of messenger RNA upregulated in common in the 3 tissues.

CONCLUSIONS AND RELEVANCE

Gene expression in sarcoidosis involving the orbit or lacrimal gland can be distinguished from gene expression patterns in control tissue and overlaps with many transcripts upregulated or downregulated in the peripheral blood of patients with sarcoidosis. These observations suggest that common pathogenic mechanisms contribute to sarcoidosis in different sites. The observations support the hypothesis that a pattern of gene expression profiles could provide diagnostic information in patients with sarcoidosis.

[Sarcoidosis : Organ involvement, diagnosis, current treatment]

Sarcoidosis is characterized by the appearance of noncausating, epitheloid cell granulomas, primarily in skin and lung. Hereditary disposition is well known; additional infection-associated triggers play a role for the development of inflammation mediated by T helper (Th)1 cells. Clinically, various disease courses can be observed that are characterized by the formation of skin papules at typical sites of the body which differ in their tendency to be associated with systemic organ involvement. Systemic disease without skin affections is also possible. The diagnosis is based on the typical clinical appearance, biopsy of affected tissue (e.g. skin, lung) and laboratory investigations. Additional systemic involvement needs to be excluded. In most cases, the disease is self-limited, but can also be life threatening due to organ fibrosis. The degree of (extra-)cutaneous involvement and level of discomfort are used to select the type of treatment, which ranges from topical immune suppressive agents to systemic therapy with corticosteroids. In nonresponders, additional modern immunosuppressive/immunomodulating therapeutic options are available.

Pivotal role of cerebral interleukin-23 during immunologic injury in delayed cerebral ischemia in mice

BACKGROUND

Interleukin-23 (IL-23) is required for T helper 17 (Th17) cell responses and IL-17 production in ischemic stroke. We previously showed that the IL-23/IL-17 axis aggravates immune injury after cerebral infarction in mice. However, IL-23 might activate other cytokines and transcription factor forkhead box P3 (Foxp3) production in cerebral ischemia. We aimed to determine whether IL-23p19 knockdown prevents cerebral ischemic injury by reducing ischemic-induced inflammation.

METHODS

Ischemic stroke models were established by permanent middle cerebral arterial occlusion (pMCAO) in male C57BL/6 mice. In vivo gene knockdown was achieved by intravenous delivery of lentiviral vectors (LVs) encoding IL-23p19 short hairpin RNA (LV-IL-23p19 shRNA). Enzyme-linked immunoassay (ELISA) and quantitative real-time polymerase chain reaction (qRT-PCR) confirmed inhibitory efficiency. Behavioral deficits were evaluated by adhesive-removal somatic-sensory test. Brain infarct volume was measured at day 5 after pMCAO by 2,3,5-triphenyltetrazolium chloride (TTC) staining. Expression of IL-17, IL-4, interferon (IFN)-γ and Foxp3 in ischemic brain tissues were detected by qRT-PCR and Western blotting, respectively. Additionally, immunohistochemical staining located cytokines in ischemic brain tissues.

RESULTS

RNA interference knockdown of IL-23p19 resulted in improved neurological function and reduced infarct volume. IL-23p19 knockdown suppressed IL-17 gene and protein expression. Moreover, IL-23p19 deficiency enhanced IFN-γ and Foxp3 expressions in delayed cerebral ischemic mice, and did not impact IL-4 expression. Immunohistochemical staining showed that IL-17, IL-4, IFN-γ and Foxp3-positive cells were located around ischemic lesions of the ipsilateral hemisphere.

CONCLUSIONS

IL-23p19 knockdown prevents delayed cerebral ischemic injury by dampening the ischemia-induced inflammation, and is a promising approach for clinically managing ischemic stroke.