Potential etiologic agents in sarcoidosis

Potential Association of Cutibacterium acnes with Sarcoidosis as an Endogenous Hypersensitivity Infection

The immunohistochemical detection of Cutibacterium acnes in sarcoid granulomas suggests its potential role in granuloma formation. C. acnes is the sole microorganism ever isolated from sarcoid lesions. Histopathologic analysis of some sarcoid lymph nodes reveals latent infection and intracellular proliferation of cell-wall-deficient C. acnes followed by insoluble immune-complex formation. Activation of T helper type 1 (Th1) immune responses by C. acnes is generally higher in sarcoidosis patients than in healthy individuals. Pulmonary granulomatosis caused by an experimental adjuvant-induced allergic immune response to C. acnes is preventable by antimicrobials, suggesting that the allergic reaction targets C. acnes commensal in the lungs. C. acnes is the most common bacterium detected intracellularly in human peripheral lungs and mediastinal lymph nodes. Some sarcoidosis patients have increased amounts of C. acnes-derived circulating immune complexes, which suggests the proliferation of C. acnes in affected organs. In predisposed individuals with hypersensitive Th1 immune responses to C. acnes, granulomas may form to confine the intracellular proliferation of latent C. acnes triggered by certain host-related or drug-induced conditions. Current clinical trials in patients with cardiac sarcoidosis are evaluating combined treatment with steroids and antimicrobials during active disease with continued antimicrobial therapy while tapering off steroids after the disease subsides.

Prognostic features of sarcoidosis course in a Brazilian cohort

Objective:

To identify predictive features associated with the course of sarcoidosis at initial evaluation and to develop a predictive score.

Methods:

This was a retrospective study involving pulmonary sarcoidosis patients, classified as having a self-limited or persistent course of disease, comparing data between the outcomes by univariate analysis. Features related to persistent disease were selected by multivariate analysis and a prognostic score was designed.

Results:

The sample comprised 200 patients (mean age = 49 years). The median duration of symptoms to diagnosis was 12 months, and delayed diagnosis (> 12 months) was found in 43% of the cases. The most common radiological stage was II; 37% had reduced FVC. Relevant systemic involvement was detected in 37% of the patients. Treatment for tuberculosis was prescribed in 44 patients prior to sarcoidosis diagnosis. Treatment for sarcoidosis was required in 77% of the sample, and the disease course was persistent in 115 cases. Excluding 40 patients with fibrotic disease, prognostic factors to persistent disease were parenchymal involvement, delayed diagnosis, dyspnea, relevant systemic involvement, and reduced FVC. On the basis of the analysis, a 3-letter scoring system (A, B and C) was developed according to the selected factors. The positive predictive values for persistent course for A (≤ 1 point) and C scores (≥ 4 points) were 12.5% and 81.8%, respectively.

Conclusions:

A score can be derived by selected features at initial evaluation, allowing the prediction of outcomes in a significant number of sarcoidosis patients.

Clinical phenotyping in sarcoidosis management

Sarcoidosis is a heterogeneous granulomatous disease. Biological markers and clinical features could allow specific phenotypes to be associated with different prognosis, severity and treatment responses. This retrospective multicentre study aims to analyse the clinical and immunological features of sarcoidosis and to identify a routine non-invasive biomarker useful in clinical practice.

[Pulmonary and Cardiac Sarcoidosis - Diagnosis and Therapy]

Sarcoidosis occurs predominantly in younger adults and may involve multiple organ systems. Although classical features such as bihilar lymphadenopathy, low grade fever, fatigue, pulmonary opacities, ocular lesions and arthritis occur frequently it must be kept in mind that sarcoidosis is able to mimic virtually any other disease. A thorough and systematic diagnostic strategy is warranted since even the histological hallmark of non-caseating granulomas occurs in a variety of other granulomatous diseases and even malignancies. A firm diagnosis is based on a match of clinical features, imaging results and histopathological findings. The Scadding classification describes four different types, not stages, of thoracic sarcoidosis based on mediastinal lymph node and lung parenchyma involvement. Medical treatment of pulmonary sarcoidosis is indicated only in patients exhibiting progressive disease and/or organ function impairment. Cardiac sarcoidosis manifests itself by clinical signs of heart failure, impaired cardiac function and arrhythmias including ventricular tachycardia, ventricular fibrillation and AV-conduction abnormalities. Patients with symptomatic or suspected cardiac sarcoidosis require rapid and elaborate diagnostic testing including cardiac MRI and PET imaging. Referral to a specialized center should be considered to establish a firm diagnosis and to initiate medical treatment and eventual device implantation. Oral corticosteroids, as the initial medical treatment of choice, carry side effects that must be weighed carefully against clinical benefits. Immunosuppressive therapy with methotrexate, azathioprine or TNF-blockers is usually reserved for patients that are either not responsive or intolerant to systemic steroids or that require steroid maintenance therapy above the cushing threshold. Diagnosed early and treated correctly, pulmonary and cardiac sarcoidosis mostly carry a favorable prognosis.

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.

The utility of serum C-C chemokine ligand 1 in sarcoidosis: A comparison to IgG4-related disease

We previously reported higher levels of C-C chemokine ligand (CCL) 1 in the bronchoalveolar lavage (BAL) fluid (BALF) of patients with sarcoidosis than in BALF of patients with immunoglobulin G4 (IgG4)-related disease (IgG4-RD), indicating that CCL1 might act as a marker of disease activity in sarcoidosis. Notably, less invasive sampling sources are desirable, as BAL cannot always be performed due to its inherent risk. In this study, we sought to decipher the correlation between serum levels of CCL1 and clinical characteristics of sarcoidosis. Serum samples were obtained from 44 patients with clinically confirmed sarcoidosis, 14 patients with IgG4-RD, and 14 healthy controls. The clinical and radiological findings were retrospectively evaluated. Serum levels of CCL1 were measured using a sandwich enzyme-linked immunosorbent assay. Serum levels of other 17 cytokines and chemokines were measured using a MILLIPLEX® MAP KIT and Luminex® magnetic beads. Serum levels of CCL1 were significantly higher in patients with sarcoidosis than in patients with IgG4-RD and healthy controls. Serum CCL1 was positively correlated with the degree of hilar lymph node swelling on chest computed tomography and serum levels of soluble interleukin 2 receptor. Positive correlations were also observed between serum CCL1 and total cell counts, lymphocyte counts in BALF, and serum T helper 1 mediators such as IP-10 and TNF-α in patients with sarcoidosis. Serum CCL1 levels were significantly elevated in sarcoidosis and correlated with clinical parameters of the disease. In addition, serum and BALF levels of CCL1 were positively correlated in a statistically significant manner. Although further research in this field is necessary, CCL1 might have the potential to be a reliable serological marker of disease activity in sarcoidosis.

The NLRP3 inflammasome pathway is activated in sarcoidosis and involved in granuloma formation

Sarcoidosis is a disease characterised by granuloma formation. There is an unmet need for new treatment strategies beyond corticosteroids. The NLRP3 inflammasome pathway is expressed in innate immune cells and senses danger signals to elicit inflammatory interleukin (IL)-1β; it has recently become a druggable target. This prompted us to test the role of the NLRP3 inflammasome and IL-1β pathway in granuloma formation and sarcoidosis.

19 sarcoid patients and 19 healthy volunteers were recruited into this pilot study. NLRP3 inflammasome activity was measured in bronchoalveolar lavage (BAL) cells and lung and skin biopsies using immunohistochemistry, Western blot, reverse-transcriptase PCR and ELISA. For in vivo experiments we used the trehalose 6,6′-dimycolate-granuloma mouse model and evaluated lung granuloma burden in miR-223 knockout and NLRP3 knockout mice, as well as the treatment effects of MCC950 and anti-IL-1β antibody therapy.

We found strong upregulation of the NLRP3 inflammasome pathway, evidenced by expression of activated NLRP3 inflammasome components, including cleaved caspase-1 and IL-1β in lung granuloma, and increased IL-1β release of BAL cells from sarcoid patients compared to healthy volunteers (p=0.006). mRNA levels of miR-223, a micro-RNA downregulating NLRP3, were decreased and NLRP3 mRNA correspondingly increased in alveolar macrophages from sarcoid patients (p<0.005). NLRP3 knockout mice showed decreased and miR-223 knockout mice increased granuloma formation compared to wild-type mice. Pharmacological interference using NLRP3 pathway inhibitor MCC950 or an anti-IL-1β antibody resulted in reduced granuloma formation (p<0.02).

In conclusion, our data provide evidence of upregulated inflammasome and IL-1β pathway activation in sarcoidosis and suggest both as valid therapeutic targets.

Moving target: shifting the focus to pulmonary sarcoidosis as an autoimmune spectrum disorder

Despite more than a century of research, the causative agent(s) in sarcoidosis, a heterogeneous granulomatous disorder mainly affecting the lungs, remain(s) elusive. Following identification of genetic factors underlying different clinical phenotypes, increased understanding of CD4⁺ T-cell immunology, which is believed to be central to sarcoid pathogenesis, as well as the role of B-cells and other cells bridging innate and adaptive immunity, contributes to novel insights into the mechanistic pathways influencing disease resolution or chronicity. Hopefully, new perspectives and state-of-the-art technology will help to shed light on the still-elusive enigma of sarcoid aetiology. This perspective article highlights a number of recent advances in the search for antigenic targets in sarcoidosis, as well as the main arguments for sarcoidosis as a spectrum of autoimmune conditions, either as a result of an external (microbial) trigger and/or due to defective control mechanisms regulating the balance between T-cell activation and inhibition.

Comparison of Aqueous and Vitreous Lymphocyte Populations From Two Rat Models of Experimental Uveitis

Purpose

To compare lymphocyte populations present within inflamed eyes in two rat models of autoimmune uveitis.

Methods

Experimental autoimmune uveitis (EAU) and primed mycobacterial uveitis (PMU) were initiated in Lewis rats. Aqueous and vitreous were collected at peak inflammation (PMU at day 2, EAU at day 14). The number of cells in the aqueous and vitreous was determined and compared for each eye and between the two models. Intraocular CD-19⁺ B cells, CD3⁺ T cells, and CD4⁺ or CD8⁺ T-cell subpopulations were identified by flow cytometry and compared between EAU and PMU.

Results

The median number of cells/mL collected from PMU aqueous (7.98 × 10⁷ cells/mL), was not significantly different from the number of cells collected from EAU aqueous (1.61 × 10⁷ cells/mL, P = 0.94). EAU aqueous contains a significantly larger mononuclear population (median 61%, interquartile range [IQR] 44%–67%) than PMU (median 9%, IQR 8%–10% [P < 0.0001]). Within the mononuclear population, EAU and PMU aqueous demonstrate similar proportions of CD3⁺, CD4⁺ T cells. However, EAU has a larger CD3⁺, CD8⁺, T-cell population than PMU, and this population also demonstrates co-expression of CD45R. B cells comprise a significantly larger median percentage of cells in EAU aqueous (median 18%, IQR 15%–20%) compared to PMU (median 13%, IQR 9%–15%, P = 0.006).

Conclusions

Flow cytometry analysis of intraocular lymphocytes from EAU and PMU identifies similarities and differences between the T-cell and B-cell populations present at peak inflammation. Complementary animal models that have well-defined mechanistic differences will improve our ability to test potential new therapies and bring meaningful advances into clinical practice for patients with uveitis.

Novel T7 Phage Display Library Detects Classifiers for Active Mycobacterium Tuberculosis Infection

Tuberculosis (TB) is caused by Mycobacterium tuberculosis (MTB) and transmitted through inhalation of aerosolized droplets. Eighty-five percent of new TB cases occur in resource-limited countries in Asia and Africa and fewer than 40% of TB cases are diagnosed due to the lack of accurate and easy-to-use diagnostic assays. Currently, diagnosis relies on the demonstration of the bacterium in clinical specimens by serial sputum smear microscopy and culture. These methods lack sensitivity, are time consuming, expensive, and require trained personnel. An alternative approach is to develop an efficient immunoassay to detect antibodies reactive to MTB antigens in bodily fluids, such as serum. Sarcoidosis and TB have clinical and pathological similarities and sarcoidosis tissue has yielded MTB components. Using sarcoidosis tissue, we developed a T7 phage cDNA library and constructed a microarray platform. We immunoscreened our microarray platform with sera from healthy (n = 45), smear positive TB (n = 24), and sarcoidosis (n = 107) subjects. Using a student t-test, we identified 192 clones significantly differentially expressed between the three groups at a False Discovery Rate (FDR) <0.01. Among those clones, we selected the top ten most significant clones and validated them on independent test set. The area under receiver operating characteristics (ROC) for the top 10 significant clones was 1 with a sensitivity of 1 and a specificity of 1. Sequence analyses of informative phage inserts recognized as antigens by active TB sera may identify immunogenic antigens that could be used to develop therapeutic or prophylactic vaccines, as well as identify molecular targets for therapy.

The Diagnosis, Differential Diagnosis, and Treatment of Sarcoidosis

BACKGROUND

Sarcoidosis is a granulomatous inflammatory disease of unknown cause. Its prevalence in Germany is approximately 46 per 100 000 persons.

METHODS

This article is based on pertinent publications retrieved by a selective search in PubMed.

RESULTS

A presumptive diagnosis of sarcoidosis is made in any patient with a granulomatous inflammation that is not explained by any other identifiable cause, such as an infection or foreign body. Non-caseating granulomas containing epithelioid cells are its histological hallmark. Recently developed diagnostic techniques, including positron emission tomography and magnetic resonance imaging, have made it easier to detect organ involvement and to assess the activity of the disease. The pattern of organ involvement varies from patient to patient. Many patients have a systemic inflammatory reaction with subfebrile or febrile temperatures, night sweats, weight loss, diminished physical reserve, and fatigue. Sarcoidosis often resolves spontaneously. Detection of organ involvement is not necessarily an indication for treatment, but treatment is clearly needed if there is symptomatic cardiac involvement or any involvement of the central nervous system. Oral corticosteroids are the first line of treatment. Their long-term use can cause serious complications.

CONCLUSION

The treatment of patients with sarcoidosis, particularly those with complicated disease courses, requires close collaboration of the primary care physician with a specialized interdisciplinary center.

The role of pattern recognition receptors in lung sarcoidosis

Sarcoidosis is a granulomatous disorder of unknown etiology. Infection, genetic factors, autoimmunity and an aberrant innate immune system have been explored as potential causes of sarcoidosis. The etiology of sarcoidosis remains unknown, and it is thought that it might be caused by an infectious agent in a genetically predisposed, susceptible host. Inflammation results from recognition of evolutionarily conserved structures of pathogens (Pathogen-associated molecular patterns, PAMPs) and/or from reaction to tissue damage associated patterns (DAMPs) through recognition by a limited number of germ line-encoded pattern recognition receptors (PRRs). Due to the similar clinical and histopathological picture of sarcoidosis and tuberculosis, Mycobacterium tuberculosis antigens such early secreted antigen (ESAT-6), heat shock proteins (Mtb-HSP), catalase-peroxidase (katG) enzyme and superoxide dismutase A peptide (sodA) have been often considered as factors in the etiopathogenesis of sarcoidosis. Potential non-TB-associated PAMPs include lipopolysaccharide (LPS) from the outer membrane of Gram-negative bacteria, peptidoglycan, lipoteichoic acid, bacterial DNA, viral DNA/RNA, chitin, flagellin, leucine-rich repeats (LRR), mannans in the yeast cell wall, and microbial HSPs. Furthermore, exogenous non-organic antigens such as metals, silica, pigments with/without aluminum in tattoos, pesticides, and pollen have been evoked as potential causes of sarcoidosis. Exposure of the airways to diverse infectious and non-infectious agents may be important in the pathogenesis of sarcoidosis. The current review provides and update on the role of PPRs and DAMPs in the pathogenesis of sarcoidsis.

Pulmonary sarcoidosis: an update

Sarcoidosis is a multisystem disease characterized by the presence of noncaseating granulomas, the exact etiology of which is yet to be determined. Pulmonary involvement occurs in the majority of patients and its severity ranges from asymptomatic involvement of mediastinal lymph nodes to progressive pulmonary fibrosis and chronic respiratory failure that is insensitive to treatment. Diagnosis of pulmonary sarcoidosis requires a compatible clinical picture supported by radiologic and pathologic data. A recent development in establishing the diagnosis of pulmonary sarcoidosis is endobronchial ultrasound that increases the yield of transbronchial needle aspiration of hilar and/or mediastinal lymph nodes. Fluorodeoxyglucose positron emission tomography (FDG-PET) is highly sensitive in detecting occult sites of disease and is of value in guiding biopsies of these sites. A combined imaging modality using both FDG-PET and CT scan is more sensitive than PET alone and is now the standard of care in patients requiring biopsies of active lesions. Biologic agents like anti-tumor necrosis factor antibodies are being used as second line treatment in those patients dependent on steroids or in cases of refractory sarcoidosis. Lung transplantation is the final option in suitable patients with end-stage pulmonary sarcoidosis.

The influence of comorbidities on mortality in sarcoidosis: a observational prospective cohort study

AIM

The aim of this study was to identify the frequency and prevalence of comorbidities in sarcoid patients and to assess their influence on overall mortality in the cohort of patients with sarcoidosis.

MATERIALS AND METHODS

A cohort of 557 patients with histologically confirmed sarcoidosis diagnosed between 2007 and 2011 and a group of non-sarcoid controls were observed. All patients were carefully observed for comorbidities and mortality.

RESULTS

291 males (52.2%) and 266 females (47.8%) with mean age 48.4 ± 12.0 years in sarcoidosis group and a group of 100 controls with mean age (49.25 ± 10.3) were observed. The mean number of comorbidities in both groups was similar (0.9 ± 0.99 vs 0.81 ± 0.84 NS). The frequency of thyroid disease was significantly higher in sarcoidosis group comparing to controls at the time of diagnosis (OR = 3.62 P = 0.0144). During the observation period (median 58.0 months), 16 patients died (2.9%). The mean number of comorbidities was significantly higher in the groups of non-survivors as compared to survivors (2.8 ± 1.0, vs 0.8 ± 0.9), P < 0.0001.

CONCLUSION

The comorbidity burden has strong impact on mortality in sarcoidosis. Thyroid diseases are more frequent in sarcoidosis than in non-sarcoid controls.

A functional proteomics approach to the comprehension of sarcoidosis

Pulmonary sarcoidosis (Sar) is an idiopathic disease histologically typified by non-caseating epitheliod cell sarcoid granulomas. A cohort of 37 Sar patients with chronic persistent pulmonary disease was described in this study. BAL protein profiles from 9 of these Sar patients were compared with those from 8 smoker (SC) and 10 no-smoker controls (NSC) by proteomic approach. Principal Component Analysis was performed to clusterize the samples in the corresponding conditions highlighting a differential pattern profiles primarily in Sar than SC. Spot identification reveals thirty-four unique proteins involved in lipid, mineral, and vitamin Dmetabolism, and immuneregulation of macrophage function. Enrichment analysis has been elaborated by MetaCore, revealing 14-3-3ε, α1-antitrypsin, GSTP1, and ApoA1 as "central hubs". Process Network as well as Pathway Maps underline proteins involved in immune response and inflammation induced by complement system, innate inflammatory response and IL-6signalling. Disease Biomarker Network highlights Tuberculosis and COPD as pathologies that share biomarkers with sarcoidosis. In conclusion, Sar protein expression profile seems more similar to that of NSC than SC, conversely to other ILDs. Moreover, Disease Biomarker Network revealed several common features between Sar and TB, exhorting to orientate the future proteomics investigations also in comparative BALF analysis of Sar and TB.

Immune response to Propionibacterium acnes in patients with sarcoidosis--in vivo and in vitro

BACKGROUND

Propionibacterium acnes was found in lungs and lymph nodes of patients with sarcoidosis and may induce hypersensitivity type granuloma formation. Data regarding the immune response to P. acnes of European sarcoid patients are scarce.

METHODS

We assessed the total IgG and IgA amount and specific antibodies to P. acnes and to Staphylococcus aureus, serving as a control, in BAL fluid of 64 patients with sarcoidosis and of 21 healthy volunteers. In a subcohort of sarcoid patients and controls, TNF-α and GM-CSF production of BAL cells stimulated with heat-killed P. acnes were measured.

RESULTS

In sarcoid patients, the total IgG and IgA levels in BAL fluid were significantly elevated compared to healthy volunteers. IgG and IgA titres against P. acnes and S. aureus were increased in sarcoid patients, yet based on the total amount of antibodies, only antibodies directed against P. acnes were relatively and significantly increased. Furthermore, BAL cells of sarcoid patients produced significantly more TNF-α and GM-CSF upon stimulation with heat-killed P. acnes compared to controls.

CONCLUSIONS

Patients with sarcoidosis had elevated levels of specific antibodies against P. acnes which suggest contact with this bacterium in the past. Furthermore, BAL cells of sarcoid patients produced inflammatory cytokines (TNF-α and GM-CSF) upon stimulation with P. acnes indicating potential involvement of this pathogen in the pathogenesis of sarcoidosis in some patients.

[Granulomatous lung and systemic diseases]

Granuloma formation occurs in the human body if there is a particle which persists in phagocytes and which the immune system cannot eliminate. The immune reaction of granuloma formation evolved in order to combat mycobacteria with the aim of localizing mycobacteria and to avoid spreading of mycobacteria throughout the body. Granulomatous lung diseases are often accompanied by severe, systemic inflammation. However, acute phase proteins may be only slightly elevated. The spectrum of granulomatous lung diseases is broad. Sarcoidosis is the most common granulomatous lung disease. To diagnose sarcoidosis, other infectious granulomatous lung diseases such as tuberculosis, atypical mycobacterial and fungal infection have to be ruled out. Pulmonary granuloma also evolve in the context of autoimmune diseases such as rheumatoid arthritis, granulomatosis with polyangiitis (GBA, Wegener's) and eosinophilic granulomatosis with polyangiitis (EGPA, Churg-Strauss syndrome). Furthermore, immunodeficiencies such as common variable immunodeficiency (CVID) and immune reconstitution syndrome in HIV can be associated with systemic granulomatous inflammation. Finally, occupational lung disease, particularly hypersensitivity pneumonitis, silicosis, hard metal lung, and chronic berylliosis are associated with pulmonary granuloma formation.

Meta-analysis of genetic programs between idiopathic pulmonary fibrosis and sarcoidosis

Background

Idiopathic pulmonary fibrosis (IPF) and pulmonary sarcoidosis are typical interstitial lung diseases with unknown etiology that cause lethal lung damages. There are notable differences between these two pulmonary disorders, although they do share some similarities. Gene expression profiles have been reported independently, but differences on the transcriptional level between these two entities have not been investigated.

Methods/Results

All expression data of lung tissue samples for IPF and sarcoidosis were from published datasets in the Gene Expression Omnibus (GEO) repository. After cross platform normalization, the merged sample data were grouped together and were subjected to statistical analysis for finding discriminate genes. Gene enrichments with their corresponding functions were analyzed by the online analysis engine “Database for Annotation, Visualization and Integrated Discovery” (DAVID) 6.7, and genes interactions and functional networks were further analyzed by STRING 9.0 and Cytoscape 3.0.0 Beta1. One hundred and thirty signature genes could potentially differentiate one disease state from another. Compared with normal lung tissue, tissue affected by IPF and sarcoidosis displayed similar signatures that concentrated on proliferation and differentiation. Distinctly expressed genes that could distinguish IPF from sarcoidosis are more enriched in processes of cilium biogenesis or degradation and regulating T cell activations. Key discriminative network modules involve aspects of bone morphogenetic protein receptor two (BMPR2) related and v-myb myeloblastosis viral oncogene (MYB) related proliferation.

Conclusions

This study is the first attempt to examine the transcriptional regulation of IPF and sarcoidosis across different studies based on different working platforms. Groups of significant genes were found to clearly distinguish one condition from the other. While IPF and sarcoidosis share notable similarities in cell proliferation, differentiation and migration, remarkable differences between the diseases were found at the transcription level, suggesting that the two diseases are regulated by overlapping yet distinctive transcriptional networks.

[Role of T lymphocyte cyclic nucleotides and G protein in sarcoidosis]

CD4+ T lymphocytes play a major role in the pathophysiology of sarcoidosis. Many studies have investigated the immunological and genetic abnormalities in this disease. There are few studies concerning the metabolic pathways. Essentially they concern the pathways: STAT1, MAPK38, NF-κB, Galphai, cAMP and cGMP PDE and PEMT1. Using studies in the literature and results of our own work concerning some metabolic aspects of T lymphocytes in sarcoidosis, we present a revue of the various hypotheses, which involve dysfunction of cAMP signaling pathways, such as RAS/RAF/MEK/ERK in T lymphocytes, leading to a disorder of immunity.

Therapeutic approach of hepatic sarcoidosis

PURPOSE OF REVIEW

Surveillance of hepatic involvement in sarcoidosis has not been standardized. Therefore, management of hepatic involvement is a clinical challenge. This review analyses published data on the pharmacological treatment of hepatic sarcoidosis.

RECENT FINDINGS

Only 5-30% of patients with hepatic sarcoidosis display symptoms. Occasionally, it has a rapid progressive course with serious complications, stressing an appropriate and carefully timed therapeutic approach. Because symptomatic hepatic sarcoidosis is uncommon, therapeutic studies are scarce. Answers to the questions when to initiate which treatment are lacking. Case reports describe beneficial effects of prednisone and the augmentation of cytotoxic and anti-tumor necrotic factor-α (TNF-α) therapy. However, because of small sample sizes, no meaningful conclusions could be drawn. In symptomatic hepatic sarcoidosis patients, it is recommended to start to treat the sarcoidosis with prednisone, preceded by ursodeoxycholic acid when signs of cholestasis are present. In refractory cases or when prednisone weaning is impossible, cytotoxic drugs or anti-TNF-α therapy should be considered.

SUMMARY

This review illustrates the importance of an appropriate therapeutic approach of sarcoidosis patients with hepatic involvement. It emphasizes the need for future studies to evaluate treatment options to avoid disease progression and hepatic complications.

The clinical and immunologic features of pulmonary fibrosis in sarcoidosis

Sarcoidosis is a multisystem, granulomatous disease that most often affects the lungs. The clinical course is highly variable; many patients undergo spontaneous remission, but up to a third of patients progresses to a chronic disease course. The development of pulmonary fibrosis (PF) in a subset of patients with chronic disease has a negative impact on morbidity and mortality. While sarcoidosis-associated PF can be progressive, it is often referred to as "burnt out" disease, a designation reflecting inactive granulomatous inflammation. The immune mechanisms of sarcoidosis-associated PF are not well understood. It is not clear if fibrotic processes are active from the onset of sarcoidosis in predisposed individuals, or whether a profibrotic state develops as a response to ongoing inflammation. Transforming growth factor β (TGF-β) is an important profibrotic cytokine, and in sarcoidosis, distinct genotypes of TGF-β have been identified in those with PF. The overall cytokine profile in sarcoidosis-associated PF has not been well characterized, although a transition from a T helper 1 to a T helper 2 signature has been proposed. Macrophages have important regulatory interactions with fibroblasts, and the role of alveolar macrophages in sarcoidosis-associated PF is a compelling target for further study. Elucidating the natural history of sarcoidosis-associated PF will inform our understanding of the fundamental derangements, and will enhance prognostication and the development of therapeutic strategies.

Localization of propionibacterium acnes in granulomas supports a possible etiologic link between sarcoidosis and the bacterium

Sarcoidosis likely results from the exposure of a genetically susceptible subject to an environmental agent, possibly an infectious one. Mycobacterial and propionibacterial organisms are the most commonly implicated potential etiologic agents. Propionibacterium acnes is the only microorganism, however, found in sarcoid lesions by bacterial culture. To evaluate the pathogenic role of this indigenous bacterium, we screened for the bacterium in sarcoid and non-sarcoid tissues using immunohistochemical methods with novel P. acnes-specific monoclonal antibodies that react with cell-membrane-bound lipoteichoic acid (PAB antibody) and ribosome-bound trigger-factor protein (TIG antibody). We examined formalin-fixed and paraffin-embedded samples of lungs and lymph nodes from 196 patients with sarcoidosis, and corresponding control samples from 275 patients with non-sarcoidosis diseases. The samples were mostly from Japanese patients, with 64 lymph node samples from German patients. Immunohistochemistry with PAB antibody revealed small round bodies within sarcoid granulomas in 20/27 (74%) video-assisted thoracic surgery lung samples, 24/50 (48%) transbronchial lung biopsy samples, 71/81 (88%) Japanese lymph node samples, and 34/38 (89%) German lymph node samples. PAB antibody did not react with non-sarcoid granulomas in any of the 45 tuberculosis samples or the 34 samples with sarcoid reaction. In nongranulomatous areas, small round bodies detected by PAB antibody were found in alveolar macrophages of lungs and paracortical macrophages of lymph nodes from many sarcoid and some non-sarcoid patients. Large-spheroidal acid-fast bodies, Hamazaki-Wesenberg bodies, which were found in 50% of sarcoid and 15% of non-sarcoid lymph node samples, reacted with both PAB and TIG antibodies. Electron microscopy revealed that these Hamazaki-Wesenberg bodies had a single bacterial structure and lacked a cell wall with occasional protrusions from the body. The high frequency and specificity of P. acnes, detected by PAB antibody within sarcoid granulomas, indicates that this indigenous bacterium might be the cause of granuloma formation in many sarcoid patients.

Epidemiological characteristics of sarcoidosis patients in the city of Rio de Janeiro, Brazil

OBJECTIVE

To analyze the epidemiological characteristics of sarcoidosis patients in the city of Rio de Janeiro, Brazil.

METHODS

A descriptive, case-control study involving 100 sarcoidosis patients under outpatient treatment between 2008 and 2010 at the Pedro Ernesto University Hospital, located in the city of Rio de Janeiro, Brazil. The diagnosis of sarcoidosis was based on clinical, radiological, biochemical, and histopathological criteria.

RESULTS

There was a predominance of females in the 35-40 year age bracket (range, 7-69 years), who accounted for 65% of the sample, although there was a second peak at approximately 55 years of age. The most common symptom was dyspnea (in 47%), and the most common radiological findings were pulmonary and lymph node involvement (stage II; in 43%), followed by stage III (in 20%), stage I (in 19%), stage 0 (in 15%), and stage IV (in 3%). No pleural effusion or digital clubbing was observed at diagnosis. The tuberculin skin test was negative in 94 patients. Spirometric findings at diagnosis were normal in 61 patients; indicative of obstructive lung disease in 21; and indicative of restrictive lung disease in 18. The most common biopsy sites were the lungs (principally by bronchoscopy) and the skin, the diagnosis being confirmed by biopsy in 56% and 29% of the cases, respectively. Treatment with prednisone was initiated in 75% of the patients and maintained for more than 2 years in 19.7%.

CONCLUSIONS

This study corroborates the findings of previous studies regarding the epidemiological characteristics of sarcoidosis patients.

Evidence for local dendritic cell activation in pulmonary sarcoidosis

Background

Sarcoidosis is a granulomatous disease characterized by a seemingly exaggerated immune response against a difficult to discern antigen. Dendritic cells (DCs) are pivotal antigen presenting cells thought to play an important role in the pathogenesis. Paradoxically, decreased DC immune reactivity was reported in blood samples from pulmonary sarcoidosis patients. However, functional data on lung DCs in sarcoidosis are lacking. We hypothesized that at the site of disease DCs are mature, immunocompetent and involved in granuloma formation.

Methods

We analyzed myeloid DCs (mDCs) and plasmacytoid DCs (pDCs) in broncho-alveolar lavage (BAL) and blood from newly diagnosed, untreated pulmonary sarcoidosis patients and healthy controls using 9-color flowcytometry. DCs, isolated from BAL using flowcytometric sorting (mDCs) or cultured from monocytes (mo-DCs), were functionally assessed in a mixed leukocyte reaction with naïve allogeneic CD4+ T cells. Using Immunohistochemistry, location and activation status of CD11c⁺DCs was assessed in mucosal airway biopsies.

Results

mDCs in BAL, but not in blood, from sarcoidosis patients were increased in number when compared with mDCs from healthy controls. mDCs purified from BAL of sarcoidosis patients induced T cell proliferation and differentiation and did not show diminished immune reactivity. Mo-DCs from patients induced increased TNFα release in co-cultures with naïve allogeneic CD4⁺ T cells. Finally, immunohistochemical analyses revealed increased numbers of mature CD86⁺ DCs in granuloma-containing airway mucosal biopsies from sarcoidosis patients.

Conclusion

Taken together, these finding implicate increased local DC activation in granuloma formation or maintenance in pulmonary sarcoidosis.

Sarcoidosis and tuberculosis in South Croatia: are there epidemiological similarities or not?

OBJECTIVE

Tuberculosis and sarcoidosis are chronic granulomatous diseases. Clinical, pathologic and immunologic aspects are similar although different. The authors were interested to highlight possible epidemiological similarities of these two granulomatous diseases. The objective of this study was to evaluate incidence rate as well as age, sex and geographic distribution of sarcoidosis in South Croatia and to compare it with these epidemiological characteristics of tuberculosis.

STUDY DESIGN

Retrospective.

METHODS

The study was including ten years follow up period (1997-2006), and was performed in Split-Dalmatia County, Croatia. All data were collected retrospectively and analyzed using Statistica 7 programme.

RESULTS

The mean annual incidence of sarcoidosis was 3.3/100,000 inhabitants with a mean of 15,6 cases per year. Woman accounted for 61% of all sarcoidosis cases. The mean sarcoidosis patient age was 44.94 ± 11.85 years. The peak age group was 40-49 years (31%). Significant difference according to incidence rate on the islands comparing to the rates on the coast and the mainland was observed (P = 0.003). The mean sarcoidosis mortality rate was 1.2/100,000. Statistically significant differences between sarcoidosis and tuberculosis were observed according the higher number of tuberculosis patients (P < 0.000), among males (P < 0.000), and females, too (P < 0.000) as well as in mortality rates (P = 0.401). Significantly more patients had tuberculosis on the mainland (P < 0.000) and on the coast (P < 0.000), but not in the islands (P = 0.260).

CONCLUSIONS

The results from this study showed dissimilarities in classic epidemiological patterns between sarcoidosis and tuberculosis, incidence rates, as well as sex and geographic distribution. Our findings resulted from this study might be starting point for the future epidemiological, genetic, and immunological studies.

M2 polarized macrophages and giant cells contribute to myofibrosis in neuromuscular sarcoidosis

The etiopathogenesis of sarcoidosis, a systemic granulomatous disease, still remains obscure. A multitude of organs have been described to be affected in systemic sarcoidosis. Skeletal muscles may also be affected, leading to myalgia and weakness. A workup of the specific immune response with emphasis on the macrophage response is provided herein. Affected muscle tissue from seven patients with systemic sarcoidosis was analyzed and compared with that from seven patients with other myopathies containing macrophagocytic infiltration. Monocytes/macrophages and giant cells in granulomas of muscle tissue from patients with sarcoidosis show a status of alternative activation (M2) based on their expression of CD206, CD301, arginase-1, and suppressor of cytokine signaling-1 as a consequence of a functionally type 2 helper T cell (Th2)-biased cytokine profile. Significant fibrosis and up-regulation of CCL18 were associated with the M2 phenotype of macrophages. Conversely, up-regulated Th1 cytokines did not result in significant classical activation of macrophages (M1), with poor inducible nitric oxide synthase and cyclooxygenase-2 production. Giant cell formation was further associated with up-regulated expression of DNAX-activating protein of 12 kDa (DAP12; gene symbol TYROBP). Functionally, alternative activation of macrophages on the basis of a Th2-biased immune response may induce clinical symptoms and chronic evolution of neuromuscular sarcoidosis. This is the first characterization of Th2-mediated immune mechanisms in neuromuscular sarcoidosis suggesting that a specific macrophage activation status leading to myofibrosis may be a key event in the pathogenesis of this disease.

Indoleamine 2,3-dioxygenase-expressing myeloid dendritic cells and macrophages in infectious and noninfectious cutaneous granulomas

BACKGROUND

The enzyme indoleamine 2,3-dioxygenase (IDO) degrades the essential amino acid tryptophan, and this degradation is an immunosuppressive mechanism that is mainly used by antigen-presenting cells. IDO-expressing dendritic cells and macrophages have previously been identified as components of lymph node granulomas after Listeria monocytogenes infection. In this study we undertook an analysis of IDO expression in granulomas of infectious and noninfectious origin in the human skin.

METHODS

Lesional skin biopsy specimens (n = 22) from different granulomatous skin disorders (lupus vulgaris, sarcoidosis, granuloma annulare, leprosy) were analyzed. Immunohistochemistry was performed to identify and locate the enzyme IDO within the inflammatory granulomatous infiltrate (IDO, CD11c, CD68, S100, CD3, Foxp3). Two-color immunofluorescence of IDO in combination with multiple markers was applied to characterize the IDO-expressing cells.

RESULTS

Cutaneous granulomas of different origin strongly express IDO, mainly in the center and in the ring wall of the granulomas. We demonstrate that in infectious, but also in noninfectious human cutaneous granulomas the large myeloid CD11c(+)S100(+)CD68(-) dendritic cells and the CD68(+) macrophages express IDO.

LIMITATIONS

This study was limited by the lack of details about the exact stage or maturity of granuloma formation in the specimens investigated.

CONCLUSION

These findings reveal that IDO expression in myeloid dendritic cells and macrophages is part of an integrated response of granuloma formation, which may be a unifying feature of granulomatous reactions in the skin.

Presumed tuberculosis-induced retinal vasculitis, diagnosed with positron emission tomography (18F-FDG-PET/CT), aspiration biopsy, and culture

PURPOSE

The diagnosis of tuberculosis as an etiological factor in patients with uveitis is difficult because of lack of specific diagnostic tests. The authors report 2 cases of occlusive retinal vasculitis, in which (18)F-FDG-PET/CT was helpful for the diagnosis of tuberculosis as a presumptive cause of intraocular inflammation.

METHODS

In 2 patients with severe occlusive retinal vasculitis and positive QuantiFERON TB-Gold test, (18)F-FDG-PET/CT, transbronchial needle-aspiration biopsy, and microbiological investigation were performed.

RESULTS

(18)F-FDG-PET/CT showed increased fluorodeoxyglucose uptake in some mediastinal and hilar lymph nodes. After needle-aspiration biopsy of PET-positive lymph nodes, M. tuberculosis was recovered in culture in both cases. Remission of uveitis was achieved only after a combination therapy with 3 anti-tubercular agents and systemic steroids.

CONCLUSION

The authors favor the use of (18)F-FDG-PET/CT in patients with sight-threatening intraocular inflammation and positive interferon-gamma release assay. Anti-tubercular therapy, together with anti-inflammatory treatment, may lead to a remission in such patients.

Low levels of NF-κB/p65 mark anergic CD4+ T cells and correlate with disease severity in sarcoidosis

T lymphocytes from patients with sarcoidosis respond weakly when stimulated with mitogen or antigen. However, the mechanisms responsible for this anergy are not fully understood. Here, we investigated the protein levels of nuclear transcription factor NF-κB (p50, p65, and p105), IκBα (inhibitor of NF-κB), T-cell receptor (TCR) CD3ζ-chain, tyrosine kinase p56(LCK), and nuclear factor of activated T cells c2 (NF-ATc2) in peripheral blood CD4(+) T cells from patients with sarcoidosis. Baseline expression of p65 in these lymphocytes was reduced in 50% of patients. The reduced levels of p65 in sarcoid CD4(+) T cells concurred with decreased levels of p50, p105, CD3ζ, p56(LCK), IκBα, and NF-ATc2. Polyclonal stimulation of NF-κB-deficient sarcoid T cells resulted in reduced expression of CD69 and CD154, decreased proliferation, and cytokine (i.e., interleukin 2 [IL-2] and gamma interferon [IFN-γ]) production. The clinical significance of these findings is suggested by the association between low p65 levels and the development of more severe and active sarcoidosis. Although correlative, our results support a model in which multiple intrinsic signaling defects contribute to peripheral T-cell anergy and the persistence of chronic inflammation in sarcoidosis.

A concise review of pulmonary sarcoidosis

This is an update on sarcoidosis, focusing on etiology, diagnosis, and treatment. In the area of etiopathogenesis, we now have a better understanding of the immune response that leads to the disease as well as genetic factors that modify both the risk for the disease and its clinical outcome. Several groups have also identified possible agents as a cause for sarcoidosis. Although none of these potential causes has been definitely confirmed, there is increasing evidence to support that one or more infectious agents may cause sarcoidosis, although this organism may no longer be viable in the patient. The diagnosis of sarcoidosis has been significantly aided by new technology. This includes the endobronchial ultrasound, which has been shown to increase the yield of needle aspiration of mediastinal and hilar lymph nodes. The positive emission tomography scan has proven useful for selecting possible biopsy sites by identifying organ involvement not appreciated by routine methodology. It has also helped in assessing cardiac involvement. The biologic agents, such as the anti-tumor necrosis factor antibodies, have changed the approach to refractory sarcoidosis. There is increasing evidence that the clinician can identify which patient is most likely to benefit from such therapy. As new and more potent antiinflammatory agents have been developed, it is clear that there are other factors that burden the patient with sarcoidosis, including fatigue and sarcoidosis-associated pulmonary hypertension. There have been several recent studies demonstrating treatment options for these problems.

Interstitial lung diseases in children

Interstitial lung disease (ILD) in infants and children comprises a large spectrum of rare respiratory disorders that are mostly chronic and associated with high morbidity and mortality. These disorders are characterized by inflammatory and fibrotic changes that affect alveolar walls. Typical features of ILD include dyspnea, diffuse infiltrates on chest radiographs, and abnormal pulmonary function tests with restrictive ventilatory defect and/or impaired gas exchange. Many pathological situations can impair gas exchange and, therefore, may contribute to progressive lung damage and ILD. Consequently, diagnosis approach needs to be structured with a clinical evaluation requiring a careful history paying attention to exposures and systemic diseases. Several classifications for ILD have been proposed but none is entirely satisfactory especially in children. The present article reviews current concepts of pathophysiological mechanisms, etiology and diagnostic approaches, as well as therapeutic strategies. The following diagnostic grouping is used to discuss the various causes of pediatric ILD: 1) exposure-related ILD; 2) systemic disease-associated ILD; 3) alveolar structure disorder-associated ILD; and 4) ILD specific to infancy. Therapeutic options include mainly anti-inflammatory, immunosuppressive, and/or anti-fibrotic drugs. The outcome is highly variable with a mortality rate around 15%. An overall favorable response to corticosteroid therapy is observed in around 50% of cases, often associated with sequelae such as limited exercise tolerance or the need for long-term oxygen therapy.

Antimycobacterial immune responses in patients with pulmonary sarcoidosis

INTRODUCTION

Sarcoidosis is a multisystem granulomatous disease of unknown origin. Pathogenetic involvement of Mycobacterium tuberculosis has frequently been discussed in the aetiology of sarcoidosis; however, studies still remain contradictory.

OBJECTIVE

We addressed the question of mycobacterial involvement in the pathogenesis of sarcoidosis by analysing cellular immune responses to mycobacterial antigens.

METHODS

We examined the interferon (IFN)-gamma production by enzyme-linked immunospot in response to purified protein derivate (PPD) mycobacterial-specific antigen early secretory antigenic target (ESAT)-6 and culture filtrate protein (CFP)-10 by peripheral blood mononuclear cells (PBMCs) and bronchoalveolar-lavage mononuclear cells (BALMCs) of patients with pulmonary sarcoidosis, smear-negative tuberculosis and controls.

RESULTS

Release of IFN-gamma in response to ex vivo contact with PPD, ESAT-6 or CFP-10 by BALMC and PBMC were comparable among patients with sarcoidosis and controls (PBMC P = 0.2326; BALMC P = 0.1767) and were less frequently observed in both groups compared to patients with tuberculosis (BALMC P < 0.05; PBMC P < 0.0001). Within PBMC, the immunophenotype of sarcoidosis patients differed from that of patients with tuberculosis, as well as from that of controls, while within BALMC it resembled that of patients with tuberculosis.

CONCLUSION

In contrast to patients with tuberculosis, the frequency of mycobacteria-specific local and systemic immune responses is not elevated in patients with sarcoidosis when compared to controls. The immunophenotype represents the local resemblance of the granulomatous reaction underlying tuberculosis and sarcoidosis while showing systemical difference. These observations do not support a role of an infection with M. tuberculosis in the pathogenesis of sarcoidosis.

Sarcoidosis and its otolaryngological implications

Sarcoidosis and its aetiopathogenesis, epidemiology and diagnostic procedures (including the Kveim reaction) are presented in this paper. The clinical manifestations of this disease, especially in otolaryngological organs, including the larynx, salivary glands, nose and paranasal sinuses, are described. Treatment procedures, including surgical interventions and prognosis, are also discussed.

Spontaneous recovery from progressive multifocal leukoencephalopathy in a patient with non-active sarcoidosis

We report the case of a 50-year-old female patient with non-active sarcoidosis and no kind of immunosuppression, admitted to our hospital because of increasing confusion and focal neurological deficits. Initially a tumor, herpes encephalitis, or neurosarcoidosis were suspected, but surprisingly biopsy revealed progressive multifocal leukoencephalopathy, additionally confirmed by JC-positive PCR in cerebrospinal fluid. Cases of sarcoidosis and progressive multifocal leukoencephalopathy have been reported before. This is the first case of a patient with no sign of active sarcoidosis and without immunosuppressive therapy who recovered spontaneously with a follow-up time of nearly 3 years.

ApoE-deficient mice on cholate-containing high-fat diet reveal a pathology similar to lung sarcoidosis

Sarcoidosis is a chronic disease of unknown etiology characterized by the formation of non-necrotizing epithelioid granulomas in various organs, especially in the lungs. The lack of an adequate animal model reflecting the pathogenesis of the human disease is one of the major impediments in studying sarcoidosis. In this report, we describe ApoE-/- mice on a cholate-containing high-fat diet that exhibit granulomatous lung inflammation similar to human sarcoidosis. Histological analysis revealed well-defined and non-necrotizing granulomas in about 40% of mice with the highest number of granulomas after 16 weeks on a cholate-containing high-fat diet. Granulomas contained CD4+ and CD8+ T cells, and the majority of the cells in granulomas showed immunoreactivity for the macrophage marker Mac-3. Cells with morphological features of epithelioid cells expressed angiotensin-converting enzyme, osteopontin, and cathepsin K, all characteristics of epithelioid and giant cells in granulomas of human sarcoidosis. Giant cells and nonspecific inclusions such as Schaumann's bodies and crystalline deposits were also detected in some lungs. Granulomatous inflammation resulted in progressive pulmonary fibrosis. Removal of cholate from the diet prevented the formation of lung granulomas. The observed similarities between the analyzed mouse lung granulomas and granulomas of human sarcoidosis, as well as the chronic disease character leading to fibrosis, suggest that this mouse model might be a useful tool to study sarcoidosis.

Cutaneous sarcoidosis: updates in the pathogenesis

Sarcoidosis is a multiorgan granulomatous disease in which the skin is one of the frequently involved target organs. Cutaneous involvement occurs in a third of patients with sarcoidosis and has protean manifestations. More than a century has passed since the initial description of sarcoidosis, but its cause continues to be an enigma. Recent studies have introduced several new insights into the pathogenesis of this disease. The aim of this literature review was to provide a comprehensive overview on the current updates in the pathogenesis of sarcoidosis. This review has revealed that several genetic polymorphisms are associated with an increased risk of developing sarcoidosis, suggesting that genetic susceptibility to sarcoidosis is probably polygenic. Environmental factors may also modify the susceptibility to sarcoidosis. Evidence favouring an infectious aetiology has been accumulating, but the results of studies are conflicting. The current concept is that the pathogenesis of sarcoidosis involves a T-helper-1-mediated immune response to environmental antigens in a genetically susceptible host. The studies carried out on sarcoidosis have largely focused on the pulmonary aspects and have been mainly conducted by respiratory physicians. In contrast, research conducted on the cutaneous aspects of sarcoidosis is comparatively limited. Although tremendous advances have been made, there is a significant gap between the vast knowledge accumulated on sarcoidosis in recent years and the understanding of this disease.

Dendritic cells in the pathogenesis of sarcoidosis

Sarcoidosis is a noncaseating granulomatous disease, likely of autoimmune etiology, that causes inflammation and tissue damage in multiple organs, most commonly the lung, but also skin, and lymph nodes. Reduced dendritic cell (DC) function in sarcoidosis peripheral blood compared with peripheral blood from control subjects suggests that blunted end organ cellular immunity may contribute to sarcoidosis pathogenesis. Successful treatment of sarcoidosis with tumor necrosis factor (TNF) inhibitors, which modulate DC maturation and migration, has also been reported. Together, these observations suggest that DCs may be important mediators of sarcoidosis immunology. This review focuses on the phenotype and function of DCs in the lung, skin, blood, and lymph node of patients with sarcoidosis. We conclude that DCs in end organs are phenotypically and functionally immature (anergic), while DCs in the lymph node are mature and polarize pathogenic Th1 T cells. The success of TNF inhibitors is thus likely secondary to inhibition of DC-mediated Th1 polarization in the lymph node.

Childhood sarcoidosis: A rare but fascinating disorder

Childhood sarcoidosis is a rare multisystemic granulomatous disorder of unknown etiology. In the pediatric series reported from the southeastern United States, sarcoidosis had a higher incidence among African Americans. Most reported childhood cases have occurred in patients aged 13-15 years. Macrophages bearing an increased expression of major histocompatibility class (MHC) II molecules most likely initiate the inflammatory response of sarcoidosis by presenting an unidentified antigen to CD4+ Th (helper-inducer) lymphocytes. A persistent, poorly degradable antigen driven cell-mediated immune response leads to a cytokine cascade, to granuloma formation, and eventually to fibrosis. Frequently observed immunologic features include depression of cutaneous delayed-type hypersensitivity and a heightened helper T cell type 1 (Th1) immune response at sites of disease. Circulating immune complexes, along with signs of B cell hyperactivity, may also be found. The clinical presentation can vary greatly depending upon the organs involved and age of the patient. Two distinct forms of sarcoidosis exist in children. Older children usually present with a multisystem disease similar to the adult manifestations, with frequent hilar lymphadenopathy and pulmonary infiltrations. Early-onset sarcoidosis is a unique form of the disease characterized by the triad of rash, uveitis, and arthritis in children presenting before four years of age. The diagnosis of sarcoidosis is confirmed by demonstrating a typical noncaseating granuloma on a biopsy specimen. Other granulmatous diseases should be reasonably excluded. The current therapy of choice for sarcoidosis in children with multisystem involvement is oral corticosteroids. Methotrexate given orally in low doses has been effective, safe and steroid sparing in some patients. Alternative immunosuppressive agents, such as azathioprine, cyclophosphamide, chlorambucil, and cyclosporine, have been tried in adult cases of sarcoidosis with questionable efficacy. The high toxicity profile of these agents, including an increased risk of lymphoproliferative disorders and carcinomas, has limited their use to patients with severe disease refractory to other agents. Successful steroid sparing treatment with mycophenolate mofetil was described in an adolescent with renal-limited sarcoidosis complicated by renal failure. Novel treatment strategies for sarcoidosis have been developed including the use of TNF-alpha inhibitors, such as infliximab. The long-term course and prognosis is not well established in childhood sarcoidosis, but it appears to be poorer in early-onset disease.

Markers of inflammation in sarcoidosis: blood, urine, BAL, sputum, and exhaled gas

Sarcoidosis is characterized by intense inflammation at the different sites of localization. Many different mediators, such as cytokines, chemokines, and other proteins with various functions, that participate in its complex pathogenesis have been proposed as markers of inflammation. This article examines the principal literature on these different markers analyzed in serum, bronchoalveolar lavage, expired breath, and urine. After many years of research, no single marker sufficiently sensitive and specific for diagnosis of sarcoidosis has yet been found. Greater correlation with clinical parameters is needed and proper validation.