In vitro and in vivo reactivity to fungal cell wall agents in sarcoidosis

Sarcoidosis immunopathogenesis - a new concept of maladaptive trained immunity

Sarcoidosis is a chronic immune disease of unknown origin for which we still lack an immunological framework unifying causal agents, host factors, and natural history of disease. Here, we discuss the initial triggers of disease, and how myeloid cells drive granuloma formation and contribute to immunopathogenesis. We highlight recent advances in our understanding of innate immune memory and propose the hypothesis that maladaptive innate immune training connects previous environmental exposure to granuloma maintenance and expansion. Lastly, we consider how this hypothesis may open novel therapeutic avenues, while corticosteroids remain the front-line treatment.

The potency of hematopoietic stem cell reprogramming for changing immune tone

Innate immune memory endows innate immune cells with antigen independent heightened responsiveness to subsequent challenges. The durability of this response can be mediated by inflammation induced epigenetic and metabolic reprogramming in hematopoietic stem and progenitor cells (HSPCs) that are maintained through differentiation to mature immune progeny. Understanding the mechanisms and extent of trained immunity induction by pathogens and vaccines, such as BCG, in HSPC remains a critical area of exploration with important implications for health and disease. Here we review these concepts and present new analysis to highlight how inflammatory reprogramming of HSPC can potently alter immune tone, including to enhance specific anti-tumor responses. New findings in the field pave the way for novel HSPC targeting therapeutic strategies in cancer and other contexts of immune modulation. Future studies are expected to unravel diverse and extensive effects of infections, vaccines, microbiota, and sterile inflammation on hematopoietic progenitor cells and begin to illuminate the broad spectrum of immunologic tuning that can be established through altering HSPC phenotypes. The purpose of this review is to draw attention to emerging and speculative topics in this field where we posit that focused study of HSPC in the framework of trained immunity holds significant promise.

Sarcoidosis and Autoimmune Inflammatory Syndrome Induced by Adjuvants

Currently, sarcoidosis remains one of the diseases with unknown etiology, which significantly complicates its diagnosis and treatment. Various causes of sarcoidosis have been studied for many years. Both organic and inorganic trigger factors, provoking the development of granulomatous inflammation are considered. However, the most promising and evidence-based hypothesis is the development of sarcoidosis as an autoimmune disease, provoked by various adjuvants in genetic predisposed individuals. This concept fits into the structure of the autoimmune/inflammatory syndrome, induced by adjuvants (ASIA) that was proposed in 2011 by Professor Shoenfeld Y. In this paper, the authors reveal the presence of major and minor ASIA criteria for sarcoidosis, propose a new concept of the course of sarcoidosis within the framework of ASIA, and point out the difficulties in creating a model of the disease and the selection of therapy. It is obvious that the data obtained not only bring us closer to understanding the nature of sarcoidosis, but also potentiate new studies confirming this hypothesis by obtaining a model of the disease.

Trained immunity as a possible newcomer in autoinflammatory and autoimmune diseases pathophysiology

Autoimmune disorders have been well characterized over the years and many pathways-but not all of them-have been found to explain their pathophysiology. Autoinflammatory disorders, on the other hand, are still hiding most of their molecular and cellular mechanisms. During the past few years, a newcomer has challenged the idea that only adaptive immunity could display memory response. Trained immunity is defined by innate immune responses that are faster and stronger to a second stimulus than to the first one, being the same or not. In response to the trained immunity inducer, and through metabolic and epigenetic changes of hematopoietic stem and progenitor cells in the bone marrow that are transmitted to their cellular progeny (peripheral trained immunity), or directly of tissue-resident cells (local innate immunity), innate cells responsiveness and functions upon stimulation are improved in the long-term. Innate immunity can be beneficial, but it could also be detrimental when maladaptive. Here, we discuss how trained immunity could contribute to the physiopathology of autoimmune and autoinflammatory diseases.

The Role of Cutibacterium acnes in Sarcoidosis: From Antigen to Treatable Trait?

Cutibacterium acnes (C. acnes, formerly Propionibacterium acnes) is considered to be a non-pathogenic resident of the human skin, as well as mucosal surfaces. However, it also has been demonstrated that C. acnes plays a pathogenic role in diseases such as acne vulgaris or implant infections after orthopedic surgery. Besides a role in infectious disease, this bacterium also seems to harbor immunomodulatory effects demonstrated by studies using C. acnes to enhance anti-tumor activity in various cancers or vaccination response. Sarcoidosis is a systemic inflammatory disorder of unknown causes. Cultures of C. acnes in biopsy samples of sarcoidosis patients, its presence in BAL fluid, tissue samples as well as antibodies against this bacterium found in serum of patients with sarcoidosis suggest an etiological role in this disease. In this review we address the antigenic as well as immunomodulatory potential of C. acnes with a focus on sarcoidosis. Furthermore, a potential role for antibiotic treatment in patients with sarcoidosis will be explored.

Innate and Adaptive Immunity in Noninfectious Granulomatous Lung Disease

Sarcoidosis and chronic beryllium disease are noninfectious lung diseases that are characterized by the presence of noncaseating granulomatous inflammation. Chronic beryllium disease is caused by occupational exposure to beryllium containing particles, whereas the etiology of sarcoidosis is not known. Genetic susceptibility for both diseases is associated with particular MHC class II alleles, and CD4⁺ T cells are implicated in their pathogenesis. The innate immune system plays a critical role in the initiation of pathogenic CD4⁺ T cell responses as well as the transition to active lung disease and disease progression. In this review, we highlight recent insights into Ag recognition in chronic beryllium disease and sarcoidosis. In addition, we discuss the current understanding of the dynamic interactions between the innate and adaptive immune systems and their impact on disease pathogenesis.

CD4+ T cells in the lungs of acute sarcoidosis patients recognize an Aspergillus nidulans epitope

Löfgren’s syndrome (LS) is an acute form of sarcoidosis characterized by a genetic association with HLA-DRB1*03 (HLA-DR3) and an accumulation of CD4⁺ T cells of unknown specificity in the bronchoalveolar lavage (BAL). Here, we screened related LS-specific TCRs for antigen specificity and identified a peptide derived from NAD-dependent histone deacetylase hst4 (NDPD) of Aspergillus nidulans that stimulated these CD4⁺ T cells in an HLA-DR3–restricted manner. Using ELISPOT analysis, a greater number of IFN-γ– and IL-2–secreting T cells in the BAL of DR3⁺ LS subjects compared with DR3⁺ control subjects was observed in response to the NDPD peptide. Finally, increased IgG antibody responses to A. nidulans NDPD were detected in the serum of DR3⁺ LS subjects. Thus, our findings identify a ligand for CD4⁺ T cells derived from the lungs of LS patients and suggest a role of A. nidulans in the etiology of LS.

Exploring Occupational, Recreational, and Environmental Associations in Patients With Clinically Manifest Cardiac Sarcoidosis

Background

Sarcoidosis is a condition of unknown etiology. A number of occupational, recreational, and environmental exposures have been associated with the development of extra-cardiac sarcoidosis. Patients with clinically manifest cardiac sarcoidosis (CS) have a distinct clinical phenotype. We sought to explore the exposures associated with clinically manifest CS.

Methods

Two groups of patients were recruited in a prospective registry: cases (patients with clinically manifest CS) and controls (patients without sarcoidosis and who had similar cardiac presentations to cases). A validated survey, previously used in other sarcoidosis phenotypes, was sent to all patients.

Results

A total of 113 patients met the inclusion criteria and were sent the survey, of whom 79 of 113 (69.9%) completed the survey. We found 3 environmental associations. First, we found a negative association of CS with smoking, with 8 of 43 (18.6%) CS patients being current or ex-smokers compared to 17 of 36 (47.2%) of the controls. Second, we found a positive association with mold exposure, with 21 of 43 (48.8%) CS patients having a prior history of mold exposure compared to 9 of 36 (25.0%) of the controls. After multivariable analysis, there remained significant associations between CS and smoking (odds ratio 0.14 [95% confidence interval 0.04-0.51], P = 0.002) and mold exposure (odds ratio 5.69 [95% confidence interval 1.68-19.25], P = 0.005). Finally, patients with CS and self-reported acne had a significantly longer duration of active acne (7.82 ± 3.97 years) than did control patients 2.67 ± 1.03 years (P = 0.006).

Conclusions

We found a negative association between smoking history and the diagnosis of CS. We also found a significant 5-fold increase in mold exposure and a positive association with duration of acne in patients with CS compared to controls.

Environmental Risk Factors for Sarcoidosis

Sarcoidosis is a multisystem granulomatous disease that may affect any body organ. Sarcoidosis is associated with many environmental and occupational exposures. Because the exact immunopathogenesis of sarcoidosis is unknown, it is not known whether these exposures are truly causing sarcoidosis, rendering the immune system more susceptible to the development of sarcoidosis, exacerbating subclinical cases of sarcoidosis, or causing a granulomatous condition distinct from sarcoidosis. This manuscript outlines what is known about the immunopathogenesis of sarcoidosis and postulates mechanisms whereby these exposures could cause or exacerbate the disease. We also describe the varied environmental and occupational exposures that have been associated with sarcoidosis. This includes potential infectious exposures such as mycobacteria and Propionibacterium acnes, a skin commensal bacterium, as well as non-infectious environmental exposures including inhaled bioaerosols, metal dusts and products of combustion. Further insights concerning the relationship of environmental exposures to the development of sarcoidosis may have a major impact on the prevention and treatment of this enigmatic disease.

Comparison of serum interleukin-10 level of fungal exposure among patients with pulmonary sarcoidosis and healthy people

Introduction: Sarcoidosis is a chronic systemic inflammatory disease with unknown etiology. Fungal exposure has been assumed as one of many possible causes of the disease. The prevalence of sarcoidosis is likely to be higher in the Northern Iran compared with other regions. Environmental studies have shown higher levels of fungal spores in the air of this area. Some studies have shown that fungal exposure in patients with sarcoidosis is associated with decreased levels of interleukin-10 (IL-10) serum levels. The aim of present study was comparison of the serum levels of IL-10 in patients with pulmonary sarcoidosis and healthy people. Objectives and Methods: In this current analytical, cross-sectional study, 40 patients with pulmonary sarcoidosis compared with 34 healthy individuals as a control group, who had been visited in a pulmonary referral clinic in Rasht (Guilan-Iran). Demographic data were collected by a questionnaire. Serum IL-10 levels were measured by ELISA kit. The data were analyzed by using the SPSS software (version 19). Results: The mean concentration of IL-10 serum levels were reported 10.96±9.48 pg/ml-1 and 3.77±1.47 pg/ml-1 among the patients with pulmonary sarcoidosis and healthy individuals, respectively. The significance difference was demonstrated between patients with pulmonary sarcoidosis and control group (p<0.0001). The IL-10 showed a significant difference between the patients older than 40 and those younger than 40. In statistical analysis, 4.75 pg.ml-1 was considered the cutoff point to separate patients and control group. Conclusion: The results showed that IL-10 was greater among patients who diagnosed as pulmonary sarcoidosis. There was a contrary opinion of the expectations for the role of fungal exposure as a possible cause of greater prevalence of sarcoidosis in Northern Iran. Age and stage of disease showed a significant relationship with the IL-10 serum level and requires further investigation. IL-10 might be a possible predictor of sarcoidosis along with other factors. (Sarcoidosis Vasc Diffuse Lung Dis 2018; 35: 294-298).

Sarcoidosis as an Autoimmune Disease

Despite the large number of performed studies, the etiology and pathogenesis of sarcoidosis still remain unknown. Most researchers allude to the possible autoimmune or immune-mediated genesis of the disease. This review attempts an integral analysis of currently available information suggesting an autoimmune genesis of sarcoidosis and is divided into four categories: the evaluation of clinical signs described both in patients with sarcoidosis and “classic” autoimmune diseases, the role of triggering factors in the development of sarcoidosis, the presence of immunogenic susceptibility in the development of the disease, and the analysis of cellular and humoral immune responses in sarcoidosis. Studying the etiology and pathogenesis of sarcoidosis will improve diagnostic procedures as well as the prognosis and patients' quality of life.

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.

The Potential Role of Trained Immunity in Autoimmune and Autoinflammatory Disorders

During induction of trained immunity, monocytes and macrophages undergo a functional and transcriptional reprogramming toward increased activation. Important rewiring of cellular metabolism of the myeloid cells takes place during induction of trained immunity, including a shift toward glycolysis induced through the mTOR pathway, as well as glutaminolysis and cholesterol synthesis. Subsequently, this leads to modulation of the function of epigenetic enzymes, resulting in important changes in chromatin architecture that enables increased gene transcription. However, in addition to the beneficial effects of trained immunity as a host defense mechanism, we hypothesize that trained immunity also plays a deleterious role in the induction and/or maintenance of autoimmune and autoinflammatory diseases if inappropriately activated.

Experimental models of sarcoidosis

PURPOSE OF REVIEW

Sarcoidosis is a disease caused by a complex combination of genetic susceptibility, immune networks and infectious and/or environmental agents. The onset and phenotypic variability of sarcoidosis remain poorly elucidated, not only due to the lack of clearly identified causes, but also because it is widely considered that no reliable model of this disease is available. In this review, we discuss the various models of granulomatous diseases in order to challenge this assertion.

RECENT FINDINGS

A large number of models of granulomatous diseases are available, both cellular models used to study the natural history of granulomas and experimental animal models mostly developed in rodents.

SUMMARY

Although none of the available models fully reproduces sarcoidosis, most of them generate various data supporting key concepts. Selected models with a high level of confidence among those already published may provide various pieces of the sarcoidosis jigsaw puzzle, whereas clinical data can provide other elements. A 'systems biology' approach for modelling may be a way of piecing together the various pieces of the puzzle. Finally, experimental models and a systemic approach should be considered to be tools for preclinical evaluation of the efficacy of drugs prior to testing in clinical trials.

β-glucan in the lymph nodes in sarcoidosis and in Kveim-Siltzbach test reagent

Background: Previous studies have demonstrated a relationship between biomass of fungi exposure in the home and the risk of sarcoidosis. β-glucan was present in the bronchial alveolar lavage fluid (BALF) of patients with sarcoidosis. The Kveim-Siltzbach test reagent (KSTR) induces a sarcoidosis specific, granulomatous, cutaneous response and was used to establish the diagnosis. To date, the granuloma-inducing component of KSTR is still unknown. The present study was undertaken to investigate the presence of β-glucan in the lymph nodes of patients with sarcoidosis and to determine the relationship between the amounts of this agent with disease severity and to investigate the presence of β-glucan in KSTR. Materials and methods: Lymph node aspirations were collected by transbronchial needle aspiration (TBNA) in region R4 or 7 from patients with newly diagnosed sarcoidosis. The samples were treated to isolate β-glucan and analyzed using a Limulus-based assay. Cultures of Propionibacterium ac. and Mycobacterium gordonae as well as samples of Kveim-Siltzbach test reagent were analyzed to determine β-glucan content. Results: A significant relationship was observed between the amount of the β-glucan in the lymph nodes and the extent of granuloma formation in the lung parenchyma, and the size of the lymph nodes in the mediastinum (r=0.787, p=0.0001 and r=0.664, p<0.001 respectively, Spearman's test). The samples of Kveim-Siltzbach test reagent contained high levels of β-glucan. Cultures of Propionibacterium ac. and Mycobacterium gordonae contained β-glucan, the levels of which were lower in the Mycobacterium cultures. Comments: The results support the hypothesis that β-glucan, and thus fungal exposure, are involved in the pathogenesis of sarcoidosis. (Sarcoidosis Vasc Diffuse Lung Dis 2017; 34: 130-135).

Fungal cell wall agents and bacterial lipopolysaccharide in organic dust as possible risk factors for pulmonary sarcoidosis

Background

Composition of organic dust is very complex, involving particles of microbial, animal and plant origin. Several environmental exposure studies associate microbial cell wall agents in organic dust with various respiratory symptoms and diseases. The aim of the present study was to investigate the in vitro effects of the co-exposure of fungal cell wall agents (FCWAs) and bacterial lipopolysaccharide (LPS) on inflammatory immune responses of peripheral blood mononuclear cells (PBMCs) from patients with pulmonary sarcoidosis.

Methods

PBMCs from 22 patients with pulmonary sarcoidosis and 20 healthy subjects were isolated and stimulated in vitro with FCWAs (soluble and particulate (1 → 3)-β-D-glucan, zymosan and chitosan) and/or LPS. Subsequently, cytokines were measured by ELISA and the mRNA expression of dectin-1, toll-like receptor 2 (TLR2), TLR4 and mannose receptor (MR) was analysed by real-time RT-PCR.

Results

Patients with sarcoidosis had a significantly higher secretion of inflammatory cytokines tumour necrosis factor-alpha (TNF-α), interleukin-6 (IL-6), IL-10 and IL-12 (1.7-fold, 2.0-fold, 2.2-fold, and 2.8-fold, respectively; all p < 0.05) after in vitro co-stimulation of PBMCs with FCWAs and LPS. We showed that PBMCs from patients with sarcoidosis had a higher baseline mRNA expression of dectin-1, TLR2, TLR4 and MR (6-fold, 11-fold, 18-fold, and 4-fold, respectively). Furthermore, we found a reduced expression of dectin-1, TLR2 and TLR4 after stimulation with FCWAs and/or LPS, although the reduction was significantly weaker in patients than in healthy subjects.

Conclusions

In conclusion, co-stimulation with FCWAs and LPS of PBMC from patients with sarcoidosis caused a weaker reduction of dectin-1, TLR2, TLR4 receptors expression, which could increase the sensitivity of PBMCs, leading to excessive inflammatory cytokine responses and result in the development or progression of pulmonary sarcoidosis.

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.

Sarcoidosis: the links between epidemiology and aetiology

Sarcoidosis is a multisystem inflammatory disease, the aetiology of which has still to be resolved. The proposed mechanism is that a susceptible genotype is exposed to one or more potential antigens. A sustained inflammatory response follows, which ultimately results in pathognomonic granuloma formation. Various clinical phenotypes exist with specific genetic associations influencing disease susceptibility, protection, and clinical progression. Occupational and environmental factors, including microbial elements, may then effect the development of this disease. Sarcoidosis is a heterogeneous disease, showing geographic and racial variation in clinical presentation. It demonstrates a familial tendency and clear genotype associations. Additionally, it appears to cluster within closely associated populations (eg, work colleagues) and appears to be related to selected occupations and environmental exposures. Frequently occult, but occasionally fatal, this disease has a very variable prognosis. It is also unusual in having no specific biomarker. The epidemiology and multiple factors that appear to influence the aetiology of sarcoidosis illustrate why this disease state is frequently described as a clinical enigma.

Increased antifungal antibodies in bronchoalveolar lavage fluid and serum in pulmonary sarcoidosis

The recent studies suggest a role of fungi in development of sarcoidosis. Moreover, the immune response in sarcoidosis and fungal infection shows a striking similarity. We formulated a hypothesis of the possible increase in antifungal antibodies in bronchoalveolar lavage fluid (BALF) and serum in pulmonary sarcoidosis. BALF and serum levels of IgG-, IgM- and IgA-specific antibodies against the cell wall β-D-glucan and mannan of Candida albicans and Saccharomyces cerevisiae were tested in 47 patients (29 pulmonary sarcoidosis patients and 18 patients with other interstitial lung diseases (ILD - control group)) and 170 healthy controls. Our results proved: (1) an increase in IgG-, IgM- and IgA-specific antifungal antibodies in BALF in pulmonary sarcoidosis compared with the control group (C. albicans: IgG: P = 0.0329, IgM: P = 0.0076, IgA: P = 0.0156; S. cerevisiae: IgG: P = 0.0062, IgM: P = 0.0367, IgA: P = 0.0095) and (2) elevated levels of serum antifungal antibodies in pulmonary sarcoidosis compared with healthy controls (C. albicans: IgG: P = 0.0329, IgM: P = 0.0076, IgA: P = 0.0156; S. cerevisiae: IgG: P > 0.05, IgM: P < 0.05, IgA: P < 0.001). The study showed increased serum and BALF levels of antifungal antibodies in pulmonary sarcoidosis. The hypothesis that fungal infection is one of the possible aetiologic agents of sarcoidosis is interesting and deserves further attention.

Fungal exposure and low levels of IL-10 in patients with sarcoidosis

BACKGROUND AND OBJECTIVES

Sarcoidosis is an inflammatory disease with increased levels of inflammatory cytokines. Previous studies have shown a relation between the degree of granuloma infiltration and serum cytokine levels, except for interleukin- (IL-) 10. The aim of the study was to further investigate the serum levels of IL-10 in patients with sarcoidosis and relate them to fungal exposure in terms of the amount of fungi in the air of their homes and β-glucan in bronchoalveolar lavage (BAL) fluid.

METHODS

Patients with sarcoidosis (n = 71) and healthy controls (n = 27) were enrolled. IL-10 was determined in serum. BAL was performed and the amount of β-glucan was measured. Domestic exposure to fungi was determined by measuring airborne β-N-acetylhexosaminidase (NAHA) in the bedrooms.

RESULTS

At high levels of fungal exposure (domestic fungal exposure and β-glucan in BAL), serum IL-10 values were lower than at low and intermediate exposure levels.

CONCLUSION

The low serum IL-10 values at high fungal exposure suggest that fungal cell wall agents play a role in granuloma formation in sarcoidosis by inhibiting the secretion of the anti-inflammatory cytokine IL-10.

Gene expression profiles in granuloma tissue reveal novel diagnostic markers in sarcoidosis

Sarcoidosis is an immune-mediated multisystem disease characterized by the formation of non-caseating granulomas. The pathogenesis of sarcoidosis is unclear, with proposed infectious or environmental antigens triggering an aberrant immune response in susceptible hosts. Multiple pro-inflammatory signaling pathways have been implicated in mediating macrophage activation and granuloma formation in sarcoidosis, including IFN-γ/STAT-1, IL-6/STAT-3, and NF-κB. It is difficult to distinguish sarcoidosis from other granulomatous diseases or assess disease severity and treatment response with histopathology alone. Therefore, development of improved diagnostic tools is imperative. Herein, we describe an efficient and reliable technique to classify granulomatous disease through selected gene expression and identify novel genes and cytokine pathways contributing to the pathogenesis of sarcoidosis. We quantified the expression of twenty selected mRNAs extracted from formalin-fixed paraffin embedded (FFPE) tissue (n = 38) of normal lung, suture granulomas, sarcoid granulomas, and fungal granulomas. Utilizing quantitative real-time RT-PCR we analyzed the expression of several genes, including IL-6, COX-2, MCP-1, IFN-γ, T-bet, IRF-1, Nox2, IL-33, and eotaxin-1 and revealed differential regulation between suture, sarcoidosis, and fungal granulomas. This is the first study demonstrating that quantification of target gene expression in FFPE tissue biopsies is a potentially effective diagnostic and research tool in sarcoidosis.

Inflammatory markers and pulmonary granuloma infiltration in sarcoidosis

BACKGROUND AND OBJECTIVE

Previous studies have demonstrated increases of inflammatory mediators in sarcoidosis while epidemiological studies have also demonstrated an association with increased fungi exposure. This study measured the level of β-glucan in the lungs and of inflammatory mediators in serum, and correlated both with the extent of pulmonary granuloma infiltration.

METHODS

This is a cross-sectional study of 98 patients with sarcoidosis and 26 controls. β-glucan, a cell wall constituent of fungi, was measured in bronchoalveolar lavage. Inflammatory mediator levels were determined in serum. The extent of granuloma infiltration was estimated on the chest X-ray. Exposure to fungi at home was determined by taking air samples in bedrooms and analysing for the presence of β-N-acetylhexosaminidase.

RESULTS

Significantly, higher levels of β-glucan were found in broncho-alveolar lavage in subjects with sarcoidosis as compared with controls. There were significant positive relationships between the extent of granuloma infiltration and the levels of the different inflammatory mediators, except for interleukin-10. Domestic fungal exposure was higher among subjects with sarcoidosis.

CONCLUSIONS

This is the first time that a specific agent, previously suspected to be related to the risk of sarcoidosis, has been detected in the lung of subjects with sarcoidosis and related to the levels of inflammatory mediators and the degree of home exposure to fungi. The results suggest that exposure to fungi should be explored when investigating patients with sarcoidosis.

Triggering receptor expressed on myeloid cells-1 and 2 in bronchoalveolar lavage fluid in pulmonary sarcoidosis

BACKGROUND AND OBJECTIVE

Pulmonary sarcoidosis (PS) is characterized by the formation of granulomas in the lungs and has been associated with infection by microorganisms. Triggering receptor expressed on the surface of myeloid cells (TREM)-1 is overexpressed in response to infection while TREM-2 is involved in granuloma formation. We hypothesized that these receptors are overexpressed in PS and might be useful for diagnostic testing.

METHODS

Cell surface TREM-1 and TREM-2 expression in cells obtained at bronchoalveolar lavage (BAL) was measured in individuals with sarcoidosis (n = 26) and compared with that seen in individuals with other interstitial lung diseases (ILD) (n = 27).

RESULTS

TREM-1 and TREM-2 expression was significantly increased in sarcoidosis compared with other ILD: total number of TREM-1, P = 0.0039 (23.81 vs 13.50 cells/μl), TREM-2, P < 0.0001 (32.81 vs 7.76 cells/μl); percentage of TREM-1: P = 0.0002 (41.30% vs 15.70%), TREM-2: P < 0.0001 (34% vs 9.60%); and mean fluorescence of TREM-1: P = 0.0005 (5.43 vs 1.96), TREM-2: P = 0.0011 (6.85 vs 2.77). Increase in both of these receptors seems to be typical for PS. In discriminating sarcoidosis from other ILD, the specificity (96%) and sensitivity (72%) of the combination of TREM-1 and TREM-2 was high.

CONCLUSIONS

Increased TREM-1 and TREM-2 cell surface expression is observed in sarcoidosis. Evaluation of BAL cell expression of both of these receptors may serve as a diagnostic marker for sarcoidosis.

Human chitotriosidase: a sensitive biomarker of sarcoidosis

BACKGROUND

Sarcoidosis is a multisystem granulomatous disease of unknown etiology. No suitable biomarkers are available to evaluate the evolution of this disease, which still has an unpredictable clinical course. Some years ago our research group proposed chitotriosidase as a potential biomarker with prognostic value, that however needed to be validated.

AIMS AND METHODS

The aims of this study were to evaluate the sensitivity and specificity of chitotriosidase in a population of 232 sarcoidosis patients under the observation of our Sarcoidosis Regional Referral Centre in Siena and to analyse enzyme concentrations in different disease phenotypes (as defined by the recently published COS classification) to define its prognostic value.

RESULTS

Serum chitotriosidase concentrations were significantly higher in patients than in healthy controls (p<0.0001) and were directly correlated with ACE levels (r=0.25, p<0.0001). ROC curve analysis revealed 88.6 % sensitivity and 92.8 % specificity. Enzyme concentrations were significantly higher in stage 3 sarcoidosis than in stage 0 (p=0.02). The lowest concentrations of chitotriosidase were found in untreated patients in remission (COS-1), while the highest enzyme concentrations were found in symptomatic patients with persistent disease on steroids and with functional deterioration in the last year (COS-9). In COS-9 subgroup, chitotriosidase decreased significantly after the increasing of steroid dose or the introduction of a new immunosuppressant therapy (p<0.01).

CONCLUSION

Chitotriosidase proved to be a biomarker with good sensitivity and specificity that is easily detected in serum. It can be proposed in clinical practice to identify progressive patients requiring close follow-up, to detect relapses and to evaluate the effects of therapy.

Occupational causes of sarcoidosis

PURPOSE OF REVIEW

Sarcoidosis, the multiorgan granulomatous disease of unknown cause, remains mysterious. Several important investigations in the past 2 years add to the accumulating evidence for both occupational and environmental causes of granulomatous inflammation.

RECENT FINDINGS

This review considers the most recent studies that contribute to the hypothesis that sarcoidosis occurs when individuals are exposed to foreign antigens and to inorganic particulates that promote inflammation. Major recent findings, such as those emerging from the study of World Trade Center responders, the study of nanoparticles, and cases of work-associated sarcoidosis, support the probability that occupational, as well as environmental, exposures to inflammatory stimuli trigger sarcoidosis-like illness. Major recent studies of microbially rich indoor environments, including moldy indoor workplaces and mycobacterially contaminated settings, contribute to the evidence that a variety of microbial antigens serve as targets for the hypersensitivity immune response in an inflammatory milieu.

SUMMARY

There is increasing evidence that sarcoidosis can occur in workplace settings in which there is exposure to both foreign antigens and inorganic triggers of inflammation that promote an exuberant granulomatous immune response. It is likely that sarcoidosis has more than one cause.