Current Insights in Genetics of Sarcoidosis: Functional and Clinical Impacts

Targeting cytokine networks in neuroinflammatory diseases

In neuroinflammatory diseases, systemic (blood-borne) leukocytes invade the central nervous system (CNS) and lead to tissue damage. A causal relationship between neuroinflammatory diseases and dysregulated cytokine networks is well established across several preclinical models. Cytokine dysregulation is also observed as an inadvertent effect of cancer immunotherapy, where it often leads to neuroinflammation. Neuroinflammatory diseases can be separated into those in which a pathogen is at the centre of the immune response and those of largely unknown aetiology. Here, we discuss the pathophysiology, cytokine networks and therapeutic landscape of 'sterile' neuroinflammatory diseases such as multiple sclerosis (MS), neuromyelitis optica spectrum disorder (NMOSD), neurosarcoidosis and immune effector cell-associated neurotoxicity syndrome (ICANS) triggered by cancer immunotherapy. Despite successes in targeting cytokine networks in preclinical models of neuroinflammation, the clinical translation of targeting cytokines and their receptors has shown mixed and often paradoxical responses.

[Medical clinical diagnostics for indoor mould exposure - Update 2023 (AWMF Register No. 161/001)]

This article is an abridged version of the updated AWMF mould guideline "Medical clinical diagnostics in case of indoor mould exposure - Update 2023", presented in July 2023 by the German Society of Hygiene, Environmental Medicine and Preventive Medicine (Gesellschaft für Hygiene, Umweltmedizin und Präventivmedizin, GHUP), in collaboration with German and Austrian scientific medical societies, and experts. Indoor mould growth is a potential health risk, even if a quantitative and/or causal relationship between the occurrence of individual mould species and health problems has yet to be established. There is no evidence for a causal relationship between moisture/mould damage and human diseases, mainly because of the ubiquitous presence of fungi and hitherto inadequate diagnostic methods. Sufficient evidence for an association between moisture/mould damage and the following health effects has been established for: allergic respiratory diseases, allergic rhinitis, allergic rhino-conjunctivitis, allergic bronchopulmonary aspergillosis (ABPA), other allergic bronchopulmonary mycosis (ABPM), aspergilloma, Aspergillus bronchitis, asthma (manifestation, progression, exacerbation), bronchitis (acute, chronic), community-acquired Aspergillus pneumonia, hypersensitivity pneumonitis (HP; extrinsic allergic alveolitis (EEA)), invasive Aspergillosis, mycoses, organic dust toxic syndrome (ODTS) [workplace exposure], promotion of respiratory infections, pulmonary aspergillosis (subacute, chronic), and rhinosinusitis (acute, chronically invasive, or granulomatous, allergic). In this context the sensitizing potential of moulds is obviously low compared to other environmental allergens. Recent studies show a comparatively low sensitization prevalence of 3-22,5 % in the general population across Europe. Limited or suspected evidence for an association exist with respect to atopic eczema (atopic dermatitis, neurodermatitis; manifestation), chronic obstructive pulmonary disease (COPD), mood disorders, mucous membrane irritation (MMI), odor effects, and sarcoidosis. (iv) Inadequate or insufficient evidence for an association exist for acute idiopathic pulmonary hemorrhage in infants, airborne transmitted mycotoxicosis, arthritis, autoimmune diseases, cancer, chronic fatigue syndrome (CFS), endocrinopathies, gastrointestinal effects, multiple chemical sensitivity (MCS), multiple sclerosis, neuropsychological effects, neurotoxic effects, renal effects, reproductive disorders, rheumatism, sick building syndrome (SBS), sudden infant death syndrome, teratogenicity, thyroid diseases, and urticaria.The risk of infection posed by moulds regularly occurring indoors is low for healthy persons; most species are in risk group 1 and a few in risk group 2 (Aspergillus fumigatus, A. flavus) of the German Biological Agents Act (Biostoffverordnung). Only moulds that are potentially able to form toxins can be triggers of toxic reactions. Whether or not toxin formation occurs in individual cases is determined by environmental and growth conditions, water activity, temperature and above all the growth substrates.In case of indoor moisture/mould damage, everyone can be affected by odor effects and/or mood disorders.However, this is not an acute health hazard. Predisposing factors for odor effects can include genetic and hormonal influences, imprinting, context and adaptation effects. Predisposing factors for mood disorders may include environmental concerns, anxiety, condition, and attribution, as well as various diseases. Risk groups to be protected particularly regarding infection risk are immunocompromised persons according to the classification of the German Commission for Hospital Hygiene and Infection Prevention (Kommission für Krankenhaushygiene und Infektionsprävention, KRINKO) at the Robert Koch-Institute (RKI), persons suffering from severe influenza, persons suffering from severe COVID-19, and persons with cystic fibrosis (mucoviscidosis); with regard to allergic risk, persons with cystic fibrosis (mucoviscidosis) and patients with bronchial asthma must be protected. The rational diagnostics include the medical history, physical examination, and conventional allergy diagnostics including provocation tests if necessary; sometimes cellular test systems are indicated. In the case of mould infections, the reader is referred to the specific guidelines. Regarding mycotoxins, there are currently no useful and validated test procedures for clinical diagnostics. From a preventive medical point of view, it is important that indoor mould infestation in relevant magnitudes cannot be tolerated for precautionary reasons.For evaluation of mould damage in the indoor environment and appropriate remedial procedures, the reader is referred to the mould guideline issued by the German Federal Environment Agency (Umweltbundesamt, UBA).

Whole exome sequencing of a German sarcoidosis family with four affected and one spontaneous remission case

OBJECTIVES

To analyse genetic mechanisms triggering familial sarcoidosis, whole exome screening of a family of six persons with four cases of sarcoidosis and two healthy controls was performed integrating progressive and spontaneous remission cases and evaluating involved genetic alterations that could potentially determine the individual course of the disease.

METHODS

Clinical diagnostic criteria in patients of the selected sarcoidosis family were according to American Thoracic Society/European Respiratory Society/World Association of Sarcoidosis and other Granulomatous Disorders guidelines. Exome screening of four patients and the two intrafamilial healthy relatives was performed by paired-end (2 × 100 bp) sequencing. We then selected the gene variants considered pathogenic on the basis of a series of prediction software applications and presence only in members of the family affected by sarcoidosis, after subtracting the common variations observed in healthy subjects.

RESULTS

Four persons out of six family members were affected by sarcoidosis. Fifty genes with uncommon in silico pathogenic variants could be identified that differentiated affected and healthy family members. One patient with sarcoidosis showed spontaneous remission whereas the remaining three patients required immunosuppressive treatment. Subtraction analysis revealed 18 genes that distinguished the three progressive cases from the patient with spontaneous remission.

CONCLUSION

The genetic analysis of these cases with familial sarcoidosis identified several involved genes and functional pathways that could help in understanding the basic mechanisms that determine the development of the disease and that discriminate spontaneously regressive and progressive forms.

AWMF mold guideline "Medical clinical diagnostics for indoor mold exposure" - Update 2023 AWMF Register No. 161/001

None.

Sarcoidosis in first- and second-generation immigrants: a cohort study of all adults 18 years of age and older in Sweden

BACKGROUND

There is a lack of studies on sarcoidosis among immigrants, which is of interest as there may be genetic and environmental characteristics affecting immigrants from certain countries. We aimed to study hazard ratios (HRs) of sarcoidosis in first- and second-generation immigrants, comparing them with native Swedes in the total adult Swedish population.

METHODS

We conducted a nationwide study of individuals ≥18 y of age. Sarcoidosis was defined as at least two registered diagnoses in the National Patient Register between 1 January 1998 and 31 December 2018. Cox regression analysis was used to estimate HRs with 99% confidence intervals (CIs) of first registration of sarcoidosis in first- and second-generation immigrants compared with native Swedes. The Cox regression models were stratified by sex and adjusted for age, comorbidities and sociodemographic characteristics.

RESULTS

In total, 6 175 251 were included in the first-generation study, with 12 617 cases of sarcoidosis, and 4 585 529 in the second-generation study, with 12 126 cases. The overall sarcoidosis risk was lower in foreign-born men (fully adjusted HR 0.63 [99% CI 0.57 to 0.69]) but not in foreign-born women (fully adjusted HR 0.98 [99% CI 0.90 to 1.06]). The overall risk was slightly lower in second-generation immigrants (HR 0.82 [99% CI 0.78 to 0.88]). Women from Asia exhibited a higher risk (HR 1.25 [99% CI 1.02 to 1.53)], while a potential trend was observed among women from Africa (HR 1.47 [99% CI 0.99 to 2.19]).

CONCLUSIONS

Sarcoidosis risk was lower in foreign-born men but not in women and also lower in second-generation immigrants.

Advance in pathogenesis of sarcoidosis: Triggers and progression

Sarcoidosis, a multisystemic immune disease, significantly impacts patients' quality of life. The complexity and diversity of its pathogenesis, coupled with limited comprehensive research, had hampered both diagnosis and treatment, resulting in an unsatisfactory prognosis for many patients. In recent years, the research had made surprising progress in the triggers of sarcoidosis (genetic inheritance, infection and environmental factors) and the abnormal regulations on immunity during the formation of granuloma. This review consolidated the latest findings on sarcoidosis research, providing a systematic exploration of advanced studies on triggers, immune-related regulatory mechanisms, and clinical applications. By synthesizing previous discoveries, we aimed to offer valuable insights for future research directions and the development of clinical diagnosis and treatment strategies.

Noninfectious Granulomatous Lung Disease: Radiological Findings and Differential Diagnosis

Granulomatous lung diseases (GLDs) are a heterogeneous group of pathological entities that can have different clinical presentations and outcomes. Granulomas are histologically defined as focal aggregations of activated macrophages, Langerhans cells, and lymphocytes, and may form in the lungs when the immune system cannot eliminate a foreign antigen and attempts to barricade it. The diagnosis includes clinical evaluation, laboratory testing, and radiological imaging, which especially consists of high-resolution computed tomography. bronchoalveolar lavage, transbronchial needle aspiration or cryobiopsy, positron emission tomography, while genetic evaluation can improve the diagnostic accuracy. Differential diagnosis is challenging due to the numerous different imaging appearances with which GLDs may manifest. Indeed, GLDs include both infectious and noninfectious, and necrotizing and non-necrotizing granulomatous diseases and the imaging appearance of some GLDs may mimic malignancy, leading to confirmatory biopsy. The purposes of our review are to report the different noninfectious granulomatous entities and to show their various imaging features to help radiologists recognize them properly and make an accurate differential diagnosis.

Infectious Complications of Pulmonary Sarcoidosis

In this review, the infectious complications observed in sarcoidosis are considered from a practical point of view to help the clinician not to overlook them in a difficult context, as pulmonary sarcoidosis makes the recognition of superinfections more difficult. An increased incidence of community-acquired pneumonia and of opportunistic pneumonia has been reported, especially in immunosuppressed patients. Pulmonary destructive lesions of advanced sarcoidosis increase the incidence of chronic pulmonary aspergillosis and infection by other agents. Screening and treatment of latent tuberculosis infection are crucial to prevent severe tuberculosis. Severity in COVID-19 appears to be increased by comorbidities rather than by sarcoidosis per se. The diagnosis of infectious complications can be challenging and should be considered as a potential differential diagnosis when the exacerbation of sarcoidosis is suspected. These complications not only increase the need for hospitalizations, but also increase the risk of death. This aspect must be carefully considered when assessing the overall health burden associated with sarcoidosis. The impact of immune dysregulation on infectious risk is unclear except in exceptional cases. In the absence of evidence-based studies on immunosuppressants in the specific context of pulmonary sarcoidosis, it is recommended to apply guidelines used in areas outside sarcoidosis. Preventive measures are essential, beginning with an appropriate use of immunosuppressants and the avoidance of unjustified treatments and doses. This approach should take into account the risk of tuberculosis, especially in highly endemic countries. Additionally, parallel emphasis should be placed on vaccinations, especially against COVID-19.

Biomarkers and molecular endotypes of sarcoidosis: lessons from omics and non-omics studies

Sarcoidosis is a chronic granulomatous disorder characterized by unknown etiology, undetermined mechanisms, and non-specific therapies except TNF blockade. To improve our understanding of the pathogenicity and to predict the outcomes of the disease, the identification of new biomarkers and molecular endotypes is sorely needed. In this study, we systematically evaluate the biomarkers identified through Omics and non-Omics approaches in sarcoidosis. Most of the currently documented biomarkers for sarcoidosis are mainly identified through conventional "one-for-all" non-Omics targeted studies. Although the application of machine learning algorithms to identify biomarkers and endotypes from unbiased comprehensive Omics studies is still in its infancy, a series of biomarkers, overwhelmingly for diagnosis to differentiate sarcoidosis from healthy controls have been reported. In view of the fact that current biomarker profiles in sarcoidosis are scarce, fragmented and mostly not validated, there is an urgent need to identify novel sarcoidosis biomarkers and molecular endotypes using more advanced Omics approaches to facilitate disease diagnosis and prognosis, resolve disease heterogeneity, and facilitate personalized medicine.

Examination of eQTL Polymorphisms Associated with Increased Risk of Progressive Complicated Sarcoidosis in European and African Descent Subjects

Background

A limited pool of SNPs are linked to the development and severity of sarcoidosis, a systemic granulomatous inflammatory disease. By integrating genome-wide association studies (GWAS) data and expression quantitative trait loci (eQTL) single nuclear polymorphisms (SNPs), we aimed to identify novel sarcoidosis SNPs potentially influencing the development of complicated sarcoidosis.

Methods

A GWAS (Affymetrix 6.0) involving 209 African-American (AA) and 193 European-American (EA, 75 and 51 complicated cases respectively) and publicly-available GWAS controls (GAIN) was utilized. Annotation of multi-tissue eQTL SNPs present on the GWAS created a pool of ~46,000 eQTL SNPs examined for association with sarcoidosis risk and severity (Logistic Model, Plink). The most significant EA/AA eQTL SNPs were genotyped in a sarcoidosis validation cohort (n=1034) and cross-validated in two independent GWAS cohorts.

Results

No single GWAS SNP achieved significance (p<1x10-8), however, analysis of the eQTL/GWAS SNP pool yielded 621 eQTL SNPs (p<10-4) associated with 730 genes that highlighted innate immunity, MHC Class II, and allograft rejection pathways with multiple SNPs validated in an independent sarcoidosis cohort (105 SNPs analyzed) (NOTCH4, IL27RA, BTNL2, ANXA11, HLA-DRB1). These studies confirm significant association of eQTL/GWAS SNPs in EAs and AAs with sarcoidosis risk and severity (complicated sarcoidosis) involving HLA region and innate immunity.

Conclusion

Despite the challenge of deciphering the genetic basis for sarcoidosis risk/severity, these results suggest that integrated eQTL/GWAS approaches may identify novel variants/genes and support the contribution of dysregulated innate immune responses to sarcoidosis severity.

The role of the host-microbiome and metabolomics in sarcoidosis

Sarcoidosis is a complex inflammatory fibrotic disease that affects multiple organ systems. It is characterized by the infiltration of lymphocytes and mononuclear phagocytes, which form non-caseating granulomas in affected organs. The lungs and intrathoracic lymph nodes are the most commonly affected organs. The underlying cause of sarcoidosis is unknown, but it is believed to occur in genetically predisposed individuals who are exposed to pathogenic organisms, environmental contaminants, or self and non-self-antigens. Recent research has suggested that the microbiome may play a role in the development of respiratory conditions, including sarcoidosis. Additionally, metabolomic studies have identified potential biomarkers for monitoring sarcoidosis progression. This review will focus on recent microbiome and metabolomic findings in sarcoidosis, with the goal of shedding light on the pathogenesis and possible diagnostic and therapeutic approaches.

Phenotypes of Sarcoidosis-Associated Pulmonary Hypertension-A Challenging Mystery

Sarcoidosis has been a well-recognised risk factor for pulmonary hypertension (PH) for a long time, but still, the knowledge about this concatenation is incomplete. Sarcoidosis-associated PH (SAPH) is an uncommon but serious complication associated with increased morbidity and mortality among sarcoidosis patients. The real epidemiology of SAPH remains unknown, and its pathomechanisms are not fully explained. Sarcoidosis is a heterogeneous and dynamic condition, and SAPH pathogenesis is believed to be multifactorial. The main roles in SAPH development play: parenchymal lung disease with the destruction of pulmonary vessels, the extrinsic compression of pulmonary vessels by conglomerate masses, lymphadenopathy or fibrosing mediastinitis, pulmonary vasculopathy, LV dysfunction, and portal hypertension. Recently, it has been recommended to individually tailor SAPH management according to the predominant pathomechanism, i.e., SAPH phenotype. Unfortunately, SAPH phenotyping is not a straightforward process. First, there are gaps in our understanding of undergoing processes. Second, the assessment of such a pivotal element as pulmonary vasculature on a microscopic level is non-feasible in SAPH patients antemortem. Finally, SAPH is a dynamic condition, multiple phenotypes usually coexist, and patients can switch between phenotypes during the course of sarcoidosis. In this article, we summarise the basic knowledge of SAPH, describe SAPH phenotypes, and highlight some practical problems related to SAPH phenotyping.

Pulmonary Sarcoidosis: Experimental Models and Perspectives of Molecular Diagnostics Using Quantum Dots

Sarcoidosis is a complex inflammatory multisystem disease of unknown etiology that is characterised by epithelioid cell granulomatous lesions affecting various organs, mainly the lungs. In general, sarcoidosis is asymptomatic, but some cases result in severe complications and organ failure. So far, no accurate and validated modelling for clinical and pathohistological manifestations of sarcoidosis is suggested. Moreover, knowledge about disease-specific diagnostic markers for sarcoidosis is scarce. For instance, pulmonary granulomatosis is associated with the upregulated production of proinflammatory molecules: TNF-α, IL-6, CXCL1, CCL2, CCL18, CD163, serum angiotensin-converting enzyme (sACE), lysozyme, neopterin, and serum amyloid A (SAA). Quantum dots (QDs) are widely applied for molecular diagnostics of various diseases. QDs are semiconductor nanoparticles of a few nanometres in size, made from ZnS, CdS, ZnSe, etc., with unique physical and chemical properties that are useful for the labelling and detection in biological experiments. QDs can conjugate with various antibodies or oligonucleotides, allowing for high-sensitivity detection of various targets in organs and cells. Our review describes existing experimental models for sarcoidosis (in vitro, in vivo, and in silico), their advantages and restrictions, as well as the physical properties of quantum dots and their potential applications in the molecular diagnostics of sarcoidosis. The most promising experimental models include mice with TSC2 deletion and an in silico multiscale computational model of sarcoidosis (SarcoidSim), developed using transcriptomics and flow cytometry of human sarcoid biopsies. Both models are most efficient to test different candidate drugs for sarcoidosis.

Role of tumor necrosis factor-alpha in the central nervous system: a focus on autoimmune disorders

Tumor necrosis factor-alpha (TNF-α) is a pleiotropic immune cytokine that belongs to the TNF superfamily of receptor ligands. The cytokine exists as either a transmembrane or a soluble molecule, and targets two distinct receptors, TNF-α receptor 1 (TNFR1) and TNF-α receptor 2 (TNFR2), which activate different signaling cascades and downstream genes. TNF-α cellular responses depend on its molecular form, targeted receptor, and concentration levels. TNF-α plays a multifaceted role in normal physiology that is highly relevant to human health and disease. In the central nervous system (CNS), this cytokine regulates homeostatic functions, such as neurogenesis, myelination, blood-brain barrier permeability and synaptic plasticity. However, it can also potentiate neuronal excitotoxicity and CNS inflammation. The pleiotropism of TNF-α and its various roles in the CNS, whether homeostatic or deleterious, only emphasizes the functional complexity of this cytokine. Anti-TNF-α therapy has demonstrated effectiveness in treating various autoimmune inflammatory diseases and has emerged as a significant treatment option for CNS autoimmune diseases. Nevertheless, it is crucial to recognize that the effects of this therapeutic target are diverse and complex. Contrary to initial expectations, anti-TNF-α therapy has been found to have detrimental effects in multiple sclerosis. This article focuses on describing the various roles, both physiological and pathological, of TNF-α in the CNS. Additionally, it discusses the specific disease processes that are dependent or regulated by TNF-α and the rationale of its use as a therapeutic target.

Molecular Mechanism in the Development of Pulmonary Fibrosis in Patients with Sarcoidosis

Sarcoidosis is a multisystemic disease of unknown etiology characterized by the formation of granulomas in various organs, especially lung and mediastinal hilar lymph nodes. The clinical course and manifestations are unpredictable: spontaneous remission can occur in approximately two thirds of patients; up to 20% of patients have chronic course of the lung disease (called advanced pulmonary sarcoidosis, APS) resulting in progressive loss of lung function, sometimes life-threatening that can lead to respiratory failure and death. The immunopathology mechanism leading from granuloma formation to the fibrosis in APS still remains elusive. Recent studies have provided new insights into the genetic factors and immune components involved in the clinical manifestation of the disease. In this review we aim to summarize the clinical-prognostic characteristics and molecular pathways which are believed to be associated with the development of APS.

Single-cell and spatial transcriptomics reveal aberrant lymphoid developmental programs driving granuloma formation

Granulomas are lumps of immune cells that can form in various organs. Most granulomas appear unstructured, yet they have some resemblance to lymphoid organs. To better understand granuloma formation, we performed single-cell sequencing and spatial transcriptomics on granulomas from patients with sarcoidosis and bioinformatically reconstructed the underlying gene regulatory networks. We discovered an immune stimulatory environment in granulomas that repurposes transcriptional programs associated with lymphoid organ development. Granuloma formation followed characteristic spatial patterns and involved genes linked to immunometabolism, cytokine and chemokine signaling, and extracellular matrix remodeling. Three cell types emerged as key players in granuloma formation: metabolically reprogrammed macrophages, cytokine-producing Th17.1 cells, and fibroblasts with inflammatory and tissue-remodeling phenotypes. Pharmacological inhibition of one of the identified processes attenuated granuloma formation in a sarcoidosis mouse model. We show that human granulomas adopt characteristic aspects of normal lymphoid organ development in aberrant combinations, indicating that granulomas constitute aberrant lymphoid organs.

Functional link between sarcoidosis-associated gene variants and quantitative levels of bronchoalveolar lavage fluid cell types

Background

Sarcoidosis is an inflammatory disease that affects multiple organs. Cell analysis from bronchoalveolar lavage fluid (BALF) is a valuable tool in the diagnostic workup and differential diagnosis of sarcoidosis. Besides the expansion of lymphocyte expression-specific receptor segments (Vα2.3 and Vβ22) in some patients with certain HLA types, the relation between sarcoidosis susceptibility and BAL cell populations' quantitative levels is not well-understood.

Methods

Quantitative levels defined by cell concentrations of BAL cells and CD4⁺/CD8⁺ ratio were evaluated together with genetic variants associated with sarcoidosis in 692 patients with extensive clinical data. Genetic variants associated with clinical phenotypes, Löfgren's syndrome (LS) and non-Löfgren's syndrome (non-LS), were examined separately. An association test via linear regression using an additive model adjusted for sex, age, and correlated cell type was applied. To infer the biological function of genetic associations, enrichment analysis of expression quantitative trait (eQTLs) across publicly available eQTL databases was conducted.

Results

Multiple genetic variants associated with sarcoidosis were significantly associated with quantitative levels of BAL cells. Specifically, LS genetic variants, mainly from the HLA locus, were associated with quantitative levels of BAL macrophages, lymphocytes, CD3⁺ cells, CD4⁺ cells, CD8⁺ cells, CD4⁺/CD8⁺ ratio, neutrophils, basophils, and eosinophils. Non-LS genetic variants were associated with quantitative levels of BAL macrophages, CD8⁺ cells, basophils, and eosinophils. eQTL enrichment revealed an influence of sarcoidosis-associated SNPs and regulation of gene expression in the lung, blood, and immune cells.

Conclusion

Genetic variants associated with sarcoidosis are likely to modulate quantitative levels of BAL cell types and may regulate gene expression in immune cell populations. Thus, the role of sarcoidosis-associated gene-variants may be to influence cellular phenotypes underlying the disease immunopathology.

Association between sarcoidosis and HLA polymorphisms in a Czech population from Central Europe: focus on a relationship with clinical outcome and treatment

Background

Sarcoidosis is an immune-mediated systemic disease with unknown etiology affecting the lung predominantly. The clinical manifestation of sarcoidosis is rather diverse ranging from Löfgren's syndrome to fibrotic disease. Also, it differs among patients with distinct geographical and ethnic origins, consistent with environmental and genetic factors' role in its pathogenesis. Of those, the polymorphic genes of the HLA system have been previously implicated in sarcoidosis. Therefore, we have performed an association study in a well-defined cohort of Czech patients aiming to define how variation in HLA genes, may contribute to disease origin and development.

Materials and methods

Total of the 301 Czech unrelated sarcoidosis patients were diagnosed according to international guidelines. In those, HLA typing was performed using next-generation sequencing. The allele frequencies at six HLA loci (HLA-A,-B,-C,-DRB1,-DQA1, and -DQB1) observed in the patients were compared with HLA allele distribution determined in 309 unrelated healthy Czech subjects; sub-analyses of relationships between HLA and distinct sarcoidosis clinical phenotypes were performed. Associations were assessed by two-tailed Fischer's exact test with correction for multiple comparisons.

Results

We report two variants, HLA-DQB1*06:02, and HLA-DQB1*06:04, as risk factors for sarcoidosis, and three variants, HLA-DRB1*01:01, HLA-DQA1*03:01, and HLA-DQB1*03:02 as protective factors. HLA-B*08:01, HLA-C*07:01, HLA-DRB1*03:01, HLA-DQA1*05:01, and HLA-DQB1*02:01 variants associated with Löfgren's syndrome, a more benign phenotype. HLA- DRB1*03:01 and HLA-DQA1*05:01 alleles were connected with better prognosis-chest X-ray (CXR) stage 1, disease remission, and non-requirement of corticosteroid treatment. The alleles HLA-DRB1*11:01 and HLA-DQA1*05:05 are associated with more advanced disease represented by the CXR stages 2-4. HLA-DQB1*05:03 associated with sarcoidosis extrapulmonary manifestation.

Conclusion

In our Czech cohort, we document some associations between sarcoidosis and HLA previously described in other populations. Further, we suggest novel susceptibility factors for sarcoidosis, such as HLA-DQB1*06:04, and characterize associations between HLA and sarcoidosis clinical phenotypes in Czech patients. Our study also extends the role of the 8.1 ancestral haplotype (HLA-A*01:01∼HLA-B*08:01∼HLA-C*07:01∼HLA-DRB1*03:01∼HLA-DQA1*05:01∼HLA-DQB1*02:01), already implicated in autoimmune diseases, as a possible predictor of better prognosis in sarcoidosis. The general translational application of our newly reported findings for personalized patient care should be validated by an independent study from another, international referral center.

Genetics of neurosarcoidosis

Sarcoidosis is a systemic, inflammatory, granulomatous disease characterized by great variability in organ involvement, clinical course, and severity. While pulmonary manifestations are almost universal, the central and peripheral nervous systems can also be affected. Neurosarcoidosis occurs in ∼5-15% of cases and is among the manifestations with the highest morbidity and mortality. It is known that sarcoidosis has genetic underpinnings and while multiple studies aimed at identifying associations to sarcoidosis susceptibility and prognosis, very few studies have focused on neurosarcoidosis. This review summarizes the genetic studies to date, compares and contrasts those findings with other genetic effects in sarcoidosis, and offers ideas for moving the field forward.

Diagnostic challenges of a rare disease with an unusual presentation

Sarcoidosis is a chronic systemic granulomatous disease that can show overlapping clinical features with various rheumatological entities. Even though it can be more commonly associated with Sjögren syndrome and systemic lupus erythematosus, only on rare occasions, it can concomitantly occur with rheumatoid arthritis. While lacking a gold standard diagnostic tool, sarcoidosis remains an exclusion diagnosis. Moreover, an atypical presentation of a rare disease on the background of another systemic disease can be challenging, even for an experienced physician. We present a rare case of a patient with a long-standing history of rheumatoid arthritis treated with methotrexate who developed sarcoidosis with an unusual presentation and possible cardiac involvement.

Sarcoid Uveitis: An Intriguing Challenger

The purpose of our work is to describe the actual knowledge concerning etiopathogenesis, clinical manifestations, diagnostic procedures, complications and therapy of ocular sarcoidosis (OS). The study is based on a recent literature review and on the experience of our tertiary referral center. Data were retrospectively analyzed from the electronic medical records of 235 patients (461 eyes) suffering from a biopsy-proven ocular sarcoidosis. Middle-aged females presenting bilateral ocular involvement are mainly affected; eye involvement at onset is present in one-third of subjects. Uveitis subtype presentation ranges widely among different studies: panuveitis and multiple chorioretinal granulomas, retinal segmental vasculitis, intermediate uveitis and vitreitis, anterior uveitis with granulomatous mutton-fat keratic precipitates, iris nodules, and synechiae are the main ocular features. The most important complications are cataract, glaucoma, cystoid macular edema (CME), and epiretinal membrane. Therapy is based on the disease localization and the severity of systemic or ocular involvement. Local, intravitreal, or systemic steroids are the mainstay of treatment; refractory or partially responsive disease has to be treated with conventional and biologic immunosuppressants. In conclusion, we summarize the current knowledge and assessment of ophthalmological inflammatory manifestations (mainly uveitis) of OS, which permit an early diagnostic assay and a prompt treatment.

Exome Sequencing Reveals Genetic Variability and Identifies Chronic Prognostic Loci in Chinese Sarcoidosis Patients

Background

Sarcoidosis is an inflammatory disease characterized by non-caseating granuloma formation in various organs, with several recognized genetic and environmental risk factors. Despite substantial progress, the genetic determinants associated with its prognosis remain largely unknown.

Objectives

This study aimed to identify the genetic changes involved in sarcoidosis and evaluate their clinical relevance.

Methods

We performed whole-exome sequencing (WES) in 116 sporadic sarcoidosis patients (acute sarcoidosis patients, n=58; chronic sarcoidosis patients, n=58). In addition, 208 healthy controls were selected from 1000 G East Asian population data. To identify genes enriched in sarcoidosis, Fisher exact tests were performed. The identified genes were included for further pathway analysis using Gene Ontology (GO) and the Kyoto Encyclopedia of Genes and Genomes (KEGG). Additionally, we used the STRING database to construct a protein network of rare variants and Cytoscape to identify hub genes of signaling pathways.

Results

WES and Fisher’s exact test identified 1,311 variants in 439 protein-coding genes. A total of 135 single nucleotide polymorphisms (SNPs) on 30 protein-coding genes involved in the immunological process based on the GO and KEGG enrichment analysis. Pathway enrichment analysis showed osteoclast differentiation and cytokine–cytokine receptor interactions. Three missense mutations (rs76740888, rs149664918, and rs78251590) in two genes (PRSS3 and CNN2) of immune-related genes showed significantly different mutation frequencies between the disease group and healthy controls. The correlation of genetic abnormalities with clinical outcomes using multivariate analysis of the clinical features and mutation loci showed that the missense variant (rs76740888, Chr9:33796673 G>A) of PRSS3 [p=0.04, odds ratio (OR) = 2.49] was significantly associated with chronic disease prognosis. Additionally, the top two hub genes were CCL4 and CXCR4 based on protein–protein interaction (PPI) network analysis.

Conclusion

Our study provides new insights into the molecular pathogenesis of sarcoidosis and identifies novel genetic alterations in this disease, especially PRSS3, which may be promising targets for future therapeutic strategies for chronic sarcoidosis.

HLA class II variants defined by next generation sequencing are associated with sarcoidosis in Korean patients

Polymorphic genes with immune functions, namely those of the human leukocyte antigen (HLA) system, have been implicated in sarcoidosis pathogenesis. As HLA polymorphisms in sarcoidosis have not been yet investigated in the Korean population, we used next-generation sequencing (NGS), allowing detailed characterization of HLA alleles to investigate the role of HLA variation in Korean sarcoidosis patients. We enrolled 103 patients diagnosed by the ATS/ERS/WASOG guidelines at Asan Medical Centre, Seoul, Korea. Among those, genotyping of 7 HLA loci (HLA-A, -B, -C, -DQA1, -DQB1, -DRB1, -DPB1) was performed using Omixon Holotype™ kit and HLATwin software™. HLA allele frequencies were compared with frequency data on healthy Koreans from the allelic frequency databases, and 4-digit characteristics of HLA genotyping were used. Associations were assessed by two-tailed Fischer’s exact test with correction for multiple comparisons. Variants previously associated with sarcoidosis risk (HLA-C*03:04, HLA-DRB1*12:01, HLA-DRB1*14:54) and a known protective variant HLA-DPB1*04:01, were associated with sarcoidosis in Koreans. Further, we suggest new HLA variants associated with sarcoidosis risk (e.g., HLA-DQA1*05:08) and novel protective variants HLA-DQB1*03:02 and HLA-DQA1*01:02 in Koreans. This first study of HLA variation in Korean patients with sarcoidosis by precise genotyping methodology reports data that could serve future meta-analyses on HLA variation’s role in sarcoidosis.

The Evolving Landscape of Cutaneous Sarcoidosis: Pathogenic Insight, Clinical Challenges, and New Frontiers in Therapy

Sarcoidosis is a multisystem disorder of unknown etiology characterized by accumulation of granulomas in affected tissue. Cutaneous manifestations are among the most common extrapulmonary manifestations in sarcoidosis and can lead to disfiguring disease requiring chronic therapy. In many patients, skin disease may be the first recognized manifestation of sarcoidosis, necessitating a thorough evaluation for systemic involvement. Although the precise etiology of sarcoidosis and the pathogenic mechanisms leading to granuloma formation, persistence, or resolution remain unclear, recent research has led to significant advances in our understanding of this disease. This article reviews recent advances in epidemiology, sarcoidosis clinical assessment with a focus on the dermatologist's role, disease pathogenesis, and new therapies in use and under investigation for cutaneous and systemic sarcoidosis.

ANXA11 rs1049550 Associates with Löfgren’s Syndrome and Chronic Sarcoidosis Patients

Sarcoidosis is an immune mediated granulomatous disease commonly affecting the lungs. Genome wide association studies identified many genomic regions that are shared among multiple immune mediated diseases. However, ANXA11 gene polymorphism rs1049550 is exclusively associated with sarcoidosis, making it a key gene of interest for sarcoidosis disease pathogenesis. However, sarcoidosis is a heterogeneous disease and contradictory findings for ANXA11 have been reported for disease phenotypes. We performed a case–control association study to investigate if ANXA11 associates with benign (Löfgren’s syndrome (LS)) or chronic sarcoidosis and performed a meta-analysis on previously reported findings. A total of 262 sarcoidosis patients, of which 149 had LS and 113 chronic sarcoidosis, and 363 controls were genotyped for rs1049550. Meta-analysis included allele findings for rs1049550 from 6 additional studies. We found a significantly lower T allele frequency in sarcoidosis patients than in healthy controls (0.30 vs. 0.41, respectively, odds ratio (OR) 0.61, 95% confidence interval (CI) 0.48–0.77, p = 3 × 10⁻⁵). In LS the T allele frequency of 0.33, and in chronic sarcoidosis the T allele frequency of 0.26 were significantly lower than in healthy controls (OR 0.69, 95% CI 0.52–0.92, p = 0.01 and OR 0.51, 95% CI 0.36–0.70, p = 4 × 10⁻⁵, respectively). Meta-analysis including previously published European, African American and Asian cohorts confirmed the association of rs1049550 with sarcoidosis and resulted in a pooled OR of 0.70 (CI 0.66–0.75, p = 3.58 × 10⁻²⁹). Presence of the T allele of rs1049550 in ANXA11 is protective for sarcoidosis, including benign and chronic phenotypes of the disease.

Molecular analysis of inflammatory diseases

If we try to describe the search for molecular actors involved in inflammatory diseases, the picture best representing this task is a mission to unexplored worlds. However, researchers nowadays have powerful tools to support this journey to the complexity of the unknown: Next generation Sequencing technologies have provided a plethora of data describing the different OMICs possibly involved in the different inflammatory diseases. Here we focused on autoinflammatory skin diseases showing the progress of OMICs-related findings in the understanding of Syndromic HS pathogenesis. We described the studies reporting possible genotype/phenotype correlation in PASH and PAPASH patients (both unrelated or familial cases), highlighting those just genetic variations associated with the diseases have been observed, but the information on common pathways shared by PASH and PAPASH patients were lacking, thus rendering difficult to decipher the common molecular basis of these autoinflammatory conditions. Aimed at filling this gap of knowledge, we proposed an integrated OMICs approach able to identify common pathways shared by subjects suffering from PASH and PAPASH: pathway-based whole sequencing analysis allowed the identification of 4 pathways, keratinization, formation of the cornified envelope steroid metabolism and ​​Vitamin D metabolism, disrupted in PASH and PAPASH patients. Finally, we mentioned the novel bioinformatic platform, named PlatOMICs, capable of integrating OMICs experimental findings also with the ones already reported in public repositories supporting the efforts of the researchers and clinicians to discover molecular pathways shared by individuals suffering of a disease, confronting, and integrating the bench findings with the in-silico ones.

Skeletal Muscle Expression of Actinin-3 (ACTN3) in Relation to Feed Efficiency Phenotype of F2Bos indicus - Bos taurus Steers

In this study, actinin-3 (ACTN3) gene expression was investigated in relation to the feed efficiency phenotype in Bos indicus - Bos taurus crossbred steers. A measure of relative feed efficiency based on residual feed intake relative to predictions from the NRC beef cattle model was analyzed by the use of a mixed linear model that included sire and family nested within sire as fixed effects and age, animal type, sex, condition, and breed as random effects for 173 F₂ Nellore-Angus steers. Based on these residual intake observations, individuals were ranked from most efficient to least efficient. Skeletal muscle samples were analyzed from 54 steers in three groups of 18 (high efficiency, low efficiency, and a statistically average group). ACTN3, which encodes a muscle-specific structural protein, was previously identified as a candidate gene from a microarray analysis of RNA extracted from muscle samples obtained from a subset of steers from each of these three efficiency groups. The expression of ACTN3 was evaluated by quantitative reverse transcriptase PCR analysis. The expression of ACTN3 in skeletal muscle was 1.6-fold greater in the inefficient steer group than in the efficient group (p = 0.007). In addition to expression measurements, blocks of SNP haplotypes were assessed for breed or parent of origin effects. A maternal effect was observed for ACTN3 inheritance, indicating that a maternal B. indicus block conferred improved residual feed efficiency relative to the B. taurus copy (p = 0.03). A SNP haplotype analysis was also conducted for m-calpain (CAPN2) and fibronectin 1 (FN1), and a significant breed effect was observed for both genes, with B. indicus and B. taurus alleles each conferring favorable efficiency when inherited maternally (p = 0.03 and p = 0.04). Because the ACTN3 structural protein is specific to fast-twitch (type II) muscle fibers and not present in slow-twitch muscle fibers (type I), muscle samples used for expression analysis were also assayed for fiber type ratio (type II/type I). Inefficient animals had a fast fiber type ratio 1.8-fold greater than the efficient animals (p = 0.027). Because these fiber-types exhibit different metabolic profiles, we hypothesize that animals with a greater proportion of fast-twitch muscle fibers are also less feed efficient.

Transcriptome Analysis of Peripheral Blood Mononuclear Cells in Pulmonary Sarcoidosis

Background

Sarcoidosis is a granulomatous systemic disease of unknown etiology. Mononuclear cells such as macrophages or lymphocytes in lung tissue and hilar or mediastinal lymph nodes have been recognized to play an essential role in granuloma formation in pulmonary sarcoidosis. Peripheral blood mononuclear cells (PBMCs) consist of several immunocompetent cells and have been shown to play a mechanistic role in the pathogenesis of sarcoidosis. However, the genetic modifications that occur in bulk PBMCs of sarcoidosis remain to be elucidated.

Purpose

This study aimed to explore the pathobiological markers of sarcoidosis in PBMCs by comparing the transcriptional signature of PBMCs from patients with pulmonary sarcoidosis with those of healthy controls by RNA sequencing.

Methods

PBMC samples were collected from subjects with pulmonary sarcoidosis with no steroid/immunosuppressant drugs (n = 8) and healthy controls (n = 11) from August 2020 to April 2021, and RNA sequencing was performed with the PBMC samples.

Results

Principal component analysis using RNA sequencing datasets comparing pulmonary sarcoidosis with healthy controls revealed that the two groups appeared to be differentiated, in which 270 differentially expressed genes were found in PBMCs between sarcoidosis and healthy controls. Enrichment analysis for gene ontology suggested that some biological processes related to the pathobiology of sarcoidosis, such as cellular response to interleukin (IL)-1 and IFN-γ, regulation of IL-6 production, IL-8 secretion, regulation of mononuclear cell migration, and response to lipopolysaccharide, were involved. Enrichment analysis of the KEGG pathway indicated the involvement of tumor necrosis factor (TNF), toll-like receptor signaling, IL-17 signaling pathways, phagosomes, and ribosomes. Most of the genes involved in TNF and IL-17 signaling pathways and phagosomes were upregulated, while most of the ribosome-related genes were downregulated.

Conclusion

The present study demonstrated that bulk gene expression patterns in PBMCs were different between patients with pulmonary sarcoidosis and healthy controls. The changes in the gene expression pattern of PBMCs could reflect the existence of sarcoidosis lesions and influence granuloma formation in sarcoidosis. These new findings are important to strengthen our understanding of the etiology and pathobiology of sarcoidosis and indicate a potential therapeutic target for sarcoidosis.

Autoantibodies against cytoskeletons and lysosomal trafficking discriminate sarcoidosis from healthy controls, tuberculosis and lung cancers

Sarcoidosis is a systemic granulomatous disease of unknown etiology. Hypergammaglobulinemia and the presence of autoantibodies in sarcoidosis suggest active humoral immunity to unknown antigen(s). We developed a complex cDNA library derived from tissues of sarcoidosis patients. Using a high throughput method, we constructed a microarray platform from this cDNA library containing large numbers of sarcoidosis clones. After selective biopanning, 1070 sarcoidosis-specifc clones were arrayed and immunoscreend with 152 sera from patients with sarcoidosis and other pulmonary diseases. To identify the sarcoidosis classifiers two statistical approaches were conducted: First, we identified significant biomarkers between sarcoidosis and healthy controls, and second identified markers comparing sarcoidosis to all other groups. At the threshold of an False Discovery Rate (FDR) < 0.01, we identified 14 clones in the first approach and 12 clones in the second approach discriminating sarcoidosis from other groups. We used the classifiers to build a naïve Bayes model on the training-set and validated it on an independent test-set. The first approach yielded an AUC of 0.947 using 14 significant clones with a sensitivity of 0.93 and specificity of 0.88, whereas the AUC of the second option was 0.92 with a sensitivity of 0.96 and specificity of 0.83. These results suggest robust classifier performance. Furthermore, we characterized the informative phage clones by sequencing and homology searches. Large numbers of classifier-clones were peptides involved in cellular trafficking and cytoskeletons. These results show that sarcoidosis is associated with a specific pattern of immunoreactivity that can discriminate it from other diseases.

Genome-wide association study identifies BTNL2 associated with atopic asthma in children

Asthma is a heterogeneous disease characterized by chronic airway inflammation with a genetic predisposition. Butyrophilin-like 2 (BTNL2) is a member of the immunoglobulin superfamily that plays an important role in regulating T cell activation and immune homeostasis. Here, we aimed to investigate the association of the genetic variants of BTNL2 with childhood asthma and asthma-related traits by utilizing extreme asthma phenotypes and employing a genome-wide association study. Our study included 243 children with well-defined moderate to severe atopic asthma and 134 healthy children with no history of allergic diseases and allergic sensitization. DNA from these subjects was genotyped using AxiomTM Genome-Wide Array Plates. Although no single nucleotide polymorphisms (SNPs) reached a genome-wide threshold of significance, 3 SNPs, rs3817971, rs41355746, and rs41441651, at BTNL2 were significantly associated with moderate to severe atopic asthma after performing Bonferroni correction. These SNPs were also associated with the risk of allergic sensitization toward house dust mites and the presence and degree of bronchial hyperresponsiveness. Thus, we identified that BTNL2 was associated with atopic moderate to severe persistent asthma in Korean children, and this may play an important role in disease development and susceptibility.

Sarcoidosis Following Hematopoietic Stem Cell Transplantation: Clinical Characteristics and HLA Associations

Purpose

Extrinsic factors and genetic predisposition contribute to the etiology of sarcoidosis, converging in a phenotype of altered immune response associated with multisystemic inflammatory granulomatous tissue infiltration. Immunological reconstitution after hematopoietic stem cell transplantation (HSCT) may represent a unique window for the pathogenesis of the disease. We describe the incidence, clinicopathological features, and HLA associations of sarcoidosis after HSCT in a single-center cohort of patients, together with data from previously published cases.

Methods

We retrospectively analyzed clinical characteristics and HLA haplotypes from allogeneic (allo) or autologous (auto) HSCT patients from January 2001 through May 2021 at the University Medicine Goettingen (UMG), and data from previously published cases.

Results

A total number of 19 patients was identified. These included 4 patients from our center (3 allo HSCT and 1 auto HSCT) and 15 patients from the literature review. Thirteen patients had received an allo HSCT, and six patients had received an auto HSCT. Sarcoidosis occurred after a median interval of 20 (after allo HSCT) and 7 (after auto HSCT) months, respectively. The predominant HLA allele associated with sarcoidosis was HLA DRB1*03:01. Sarcoidosis involved the respiratory tract in 15 patients (three unknown, one without pulmonary involvement), and it was associated with graft-versus-host disease in 7 of 13 patients receiving allo HSCT. None of the donors or patients had a history of sarcoidosis before transplantation. Disease manifestations resolved with standard glucocorticoid treatment without long-term sequelae.

Conclusion

Sarcoidosis may occur at low frequency during reconstitution of the immune system after HSCT. HLA allele associations reflect the associations observed in the general population, particularly with DRB1*03:01. Further insights into the interplay between Tcell reconstitution and the development of sarcoidosis could also provide novel approaches to an improved understanding of the pathogenesis in sarcoidosis.

Genetic overlap between type 1 diabetes and other autoimmune diseases

Type 1 diabetes (T1D) is a chronic disease caused by the destruction of pancreatic β cells, which is driven by autoreactive T lymphocytes. It has been described that a high proportion of T1D patients develop other autoimmune diseases (AIDs), such as autoimmune thyroid disease, celiac disease, or vitiligo, which suggests the existence of common etiological factors among these disorders. In this regard, genetic studies have identified a high number of loci consistently associated with T1D that also represent established genetic risk factors for other AIDs. In addition, studies focused on identifying the shared genetic component in autoimmunity have described several common susceptibility loci with a potential role in T1D. Elucidation of this genetic overlap has been useful in identifying key molecular pathways with a pathogenic role in multiple disorders. In this review, we summarize recent advances in understanding the shared genetic component between T1D and other AIDs and discuss how the identification of common pathogenic mechanisms can help in the development of new therapeutic approaches as well as in improving the use of existing drugs.

Autophagy and Mitophagy-Related Pathways at the Crossroads of Genetic Pathways Involved in Familial Sarcoidosis and Host-Pathogen Interactions Induced by Coronaviruses

Sarcoidosis is a multisystem disease characterized by the development and accumulation of granulomas, the hallmark of an inflammatory process induced by environmental and/or infectious and or genetic factors. This auto-inflammatory disease mainly affects the lungs, the gateway to environmental aggressions and viral infections. We have shown previously that genetic predisposition to sarcoidosis occurring in familial cases is related to a large spectrum of pathogenic variants with, however, a clustering around mTOR (mammalian Target Of Rapamycin)-related pathways and autophagy regulation. The context of the COVID-19 pandemic led us to evaluate whether such genetic defects may increase the risk of a severe course of SARS-CoV2 infection in patients with sarcoidosis. We extended a whole exome screening to 13 families predisposed to sarcoidosis and crossed the genes sharing mutations with the list of genes involved in the SARS-CoV2 host-pathogen protein-protein interactome. A similar analysis protocol was applied to a series of 100 healthy individuals. Using ENRICH.R, a comprehensive gene set enrichment web server, we identified the functional pathways represented in the set of genes carrying deleterious mutations and confirmed the overrepresentation of autophagy- and mitophagy-related functions in familial cases of sarcoidosis. The same protocol was applied to the set of genes common to sarcoidosis and the SARS-CoV2-host interactome and found a significant enrichment of genes related to mitochondrial factors involved in autophagy, mitophagy, and RIG-I-like (Retinoic Acid Inducible Gene 1) Receptor antiviral response signaling. From these results, we discuss the hypothesis according to which sarcoidosis is a model for studying genetic abnormalities associated with host response to viral infections as a consequence of defects in autophagy and mitophagy processes.

Integrated transcriptomic analysis of human tuberculosis granulomas and a biomimetic model identifies therapeutic targets

Tuberculosis (TB) is a persistent global pandemic, and standard treatment for it has not changed for 30 years. Mycobacterium tuberculosis (Mtb) has undergone prolonged coevolution with humans, and patients can control Mtb even after extensive infection, demonstrating the fine balance between protective and pathological host responses within infected granulomas. We hypothesized that whole transcriptome analysis of human TB granulomas isolated by laser capture microdissection could identify therapeutic targets, and that comparison with a noninfectious granulomatous disease, sarcoidosis, would identify disease-specific pathological mechanisms. Bioinformatic analysis of RNAseq data identified numerous shared pathways between TB and sarcoidosis lymph nodes, and also specific clusters demonstrating TB results from a dysregulated inflammatory immune response. To translate these insights, we compared 3 primary human cell culture models at the whole transcriptome level and demonstrated that the 3D collagen granuloma model most closely reflected human TB disease. We investigated shared signaling pathways with human disease and identified 12 intracellular enzymes as potential therapeutic targets. Sphingosine kinase 1 inhibition controlled Mtb growth, concurrently reducing intracellular pH in infected monocytes and suppressing inflammatory mediator secretion. Immunohistochemical staining confirmed that sphingosine kinase 1 is expressed in human lung TB granulomas, and therefore represents a host therapeutic target to improve TB outcomes.

Immunopathophysiology and clinical impact of uveitis in inflammatory rheumatic diseases: An update

BACKGROUND

Uveitis is one of the most frequent ophthalmologic manifestations in rheumatology. Uveal inflammation can underlie a systemic inflammatory rheumatic disease (SIRD) in approximately 30% of cases with a significant burden on the quality of life since it represents a cause of blindness in up to 20% of cases in Western countries.

METHODS

In this review, we provide a comprehensive overview of the pathophysiology of uveitis associated with SIRDs. According to our literature survey on the epidemiology of uveitis among SIRDs, spondyloarthritides, Behçet's disease and sarcoidosis get the major impact.

RESULTS

In Behçet's uveitis, the key players are highly polarized Th1 and Th17 lymphocytes, natural killer T cells and γδ T cells. All contribute to a great destructive inflammatory environment with the most serious visual damage resulting from the involvement of the posterior segment of the eye. In contrast, spondyloarthritides-related uveitis derives from a complex interaction between genetic background and extra-ocular inflammatory mediators originating from enthesitis, arthritis, psoriatic lesions and microbiome pro-inflammatory alterations. In such conditions, the immune infiltration of CD4+ T cells, Th17 and natural killer cells along with pro-inflammatory cytokines, TNF-α among all, leads to intraocular inflammation. Lastly, granuloma formation represents the primary hallmark lesion in sarcoid uveitis. This suggests a profound link between the innate system that mainly recruits activated macrophages and adaptive system involving by Th1, Th17 and Th17.1 cells.

CONCLUSIONS

Awareness among rheumatologists of a potential severe ocular involvement generates new insights into targeted therapeutic approaches and personalized treatments for each patient.

Immunohistochemical Detection of Potential Microbial Antigens in Granulomas in the Diagnosis of Sarcoidosis

Sarcoidosis may have more than a single causative agent, including infectious and non-infectious agents. Among the potential infectious causes of sarcoidosis, Mycobacterium tuberculosis and Propionibacterium acnes are the most likely microorganisms. Potential latent infection by both microorganisms complicates the findings of molecular and immunologic studies. Immune responses to potential infectious agents of sarcoidosis should be considered together with the microorganisms detected in sarcoid granulomas, because immunologic reactivities to infectious agents reflect current and past infection, including latent infection unrelated to the cause of the granuloma formation. Histopathologic data more readily support P. acnes as a cause of sarcoidosis compared with M. tuberculosis, suggesting that normally symbiotic P. acnes leads to granuloma formation in some predisposed individuals with Th1 hypersensitivity against intracellular proliferation of latent P. acnes, which may be triggered by certain host or drug-induced conditions. Detection of bacterial nucleic acids in granulomas does not necessarily indicate co-localization of the bacterial proteins in the granulomas. In the histopathologic diagnosis of sarcoidosis, M. tuberculosis-associated and P. acnes-associated sarcoidosis will possibly be differentiated in some patients by immunohistochemistry with appropriate antibodies that specifically react with mycobacterial and propionibacterial antigens, respectively, for each etiology-based diagnosis and potential antimicrobial intervention against sarcoidosis.

Switching to an Infliximab Biosimilar Was Safe and Effective in Dutch Sarcoidosis Patients

The effect of switching from originator infliximab to biosimilar infliximab in patients with sarcoidosis is unknown. The objective of this study is to investigate the effect of switching from Remicade^® or Inflectra^® to Flixabi^® in patients with severe refractory sarcoidosis. This single center retrospective cohort study was performed at St Antonius Hospital Nieuwegein, The Netherlands. All patients diagnosed with severe refractory sarcoidosis receiving Remicade^® or Inflectra^® switched to Flixabi^®. The primary outcome was infliximab discontinuation within 6 months of switching. Secondary endpoints included adverse events and loss of clinical, functional, or inflammatory response. Out of 86 patients who switched to Flixabi^®, 79 patients had complete data. None of the 79 patients discontinued infliximab during the first 6 months after switching. Five patients reported an adverse event related to Flixabi^® treatment. We found no change from baseline in FVC, FEV1, DLCOc, 6MWT, and infliximab trough levels 26 weeks after switching. An improvement in physical functioning of 7.3 ± 13.4 points (p = 0.002) with RAND/SF36 and in biomarker sIL-2R (−475.58 ± 1452.39; p = 0.005) was observed. Switching from originator infliximab Remicade^® or biosimilar infliximab Inflectra^® to biosimilar infliximab Flixabi^® did not result in treatment discontinuation or loss of clinical/functional/inflammatory remission.

Key Players and Biomarkers of the Adaptive Immune System in the Pathogenesis of Sarcoidosis

Sarcoidosis is a systemic inflammatory disease characterized by development of granulomas in the affected organs. Sarcoidosis is often a diagnosis of exclusion, and traditionally used tests for sarcoidosis demonstrate low sensitivity and specificity. We propose that accuracy of diagnosis can be improved if biomarkers of altered lymphocyte populations and levels of signaling molecules involved in disease pathogenesis are measured for patterns suggestive of sarcoidosis. These distinctive biomarkers can also be used to determine disease progression, predict prognosis, and make treatment decisions. Many subsets of T lymphocytes, including CD8⁺ T-cells and regulatory T-cells, have been shown to be dysfunctional in sarcoidosis, and the predominant CD4⁺ T helper cell subset in granulomas appears to be a strong indicator of disease phenotype and outcome. Studies of altered B cell populations, B cell signaling molecules, and immune complexes in sarcoidosis patients reveal promising biomarkers as well as possible explanations of disease etiology. Furthermore, examined biomarkers raise questions about new treatment methods and sarcoidosis antigens.