Immunopathogenesis of sarcoidosis

BALF and BLOOD NK- cells in different stages of pulmonary sarcoidosis

Background and objective:

Data on natural killer (NK)- and natural killer T (NKT)- like cells in the immunopathogenesis of sarcoidosis remain limited. The aim was to assess NK- and NKT-like cells across different stages in bronchoalveolar lavage (BALF) versus peripheral blood (PB) in comparison to controls.

Methods:

Forty four patients (32 women and 12 men, mean age 46.6±14.4 years) with biopsy-proven sarcoidosis and 10 healthy individuals (6 women, 4 men mean age 52.6±19.1 years) were submitted to BALF. Total cells and cell differentials were counted, while CD45+, CD3+, CD4+, CD8+, CD19+, CD3-CD16/56 (NK cells) and CD3+CD16/56+ (NKT-like cells) were determined by dual flow cytometry in BALF and PB.

Results:

A significantly lower percentage of both NK and NKT-like cells was observed in BALF of controls and sarcoid patients (SP) compared to PB. Both BALF NK and NKT-cell counts were significantly higher in SP than in controls (NK: p=0.046, NKT-like: p=0.012) In addition BALF NK cell percentage differed among sarcoidosis stages (p=0.005). In PB NK-cell count was lower in sarcoidosis patients but the difference did not reach statistical significance. Also, in sarcoid patients’ BALF NK-cell percentage negatively correlated with lymphocyte percentage (r=-0.962, p<0.001).

Conclusions:

The increased count of BALF NK and NKT-like cells in sarcoidosis compared to controls along with the increase of NK cells with stage progression are in line with a growing number of investigations suggesting the involvement of NK- and NKT-like cells in the pathogenesis of sarcoidosis.

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

Purpose

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

Methods

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

Results

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

Conclusion

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

Potential immunotherapies for sarcoidosis

INTRODUCTION

Sarcoidosis is a chronic granulomatous inflammatory disease that commonly causes lung disease, but can affect other vital organs and tissues. The cause of sarcoidosis is unknown, and current therapies are commonly limited by lack of efficacy, adverse side effects, and excessive cost.

AREAS COVERED

The manuscript will provide a review of current concepts relating to the pathogenesis of sarcoidosis, and how these disease mechanisms may be leveraged to develop more effective treatments for sarcoidosis. It provides only a brief summary of currently accepted therapy, while focusing more extensively on potential novel therapies.

EXPERT OPINION

Current sarcoidosis therapeutic agents primarily target the M1 or pro-inflammatory pathways. Agents that prevent M2 polarization, a regulatory phenotype favoring fibrosis, are attractive treatment alternatives that could potentially prevent fibrosis and associated life threatening complications. Effective treatment of sarcoidosis potentially requires simultaneous modulation both M1/M2 polarization instead of suppressing one pathway over the other to restore immune competent and inactive (M0) macrophages.

Update on Treatment in Cardiac Sarcoidosis

OPINION STATEMENT

The prevalence of cardiac sarcoidosis has exponentially increased over the past decade, primarily due to increased awareness and diagnostic modalities for the disease entity. Despite an expanding patient cohort, the optimal management of cardiac sarcoidosis remains yet to be established with a significant lack of prospective trials to support current practice. Corticosteroids remain first-line treatment of this disorder, and we recommend that immunosuppressive therapy should be initiated in all patients diagnosed with cardiac sarcoidosis. Additional pharmacotherapy may be necessary based on disease manifestations and response to treatment. The use of nuclear imaging with ¹⁸fluorodeoxyglucose (¹⁸FDG) positron emission tomography (PET) to guide treatment has become more common, but lacks rigorous data from larger cohorts. Whether an improvement in inflammatory burden as assessed by ¹⁸FDG-PET is correlated with clinical outcomes is as yet unproven. Device therapy with implantable-cardioverter defibrillators should be considered in all cardiac sarcoidosis patients for either primary or secondary prevention of ventricular arrhythmias and cardiac death.

Altered Cyclooxygenase-2 Expression in Pulmonary Sarcoidosis is not Related to Clinical Classifications

Elevated COX-2 activity is associated with the development of chronic lung diseases leading to bronchial obstruction, including sarcoidosis. The aim of the study was to examine expression pattern of COX-2 messenger RNA (mRNA). Expression was performed by q-PCR method in bronchoalveolar lavage (BAL) cells and peripheral blood (PB) lymphocytes in sarcoidosis patients (n = 61) and control group (n = 30). Analysis of COX-2 mRNA expression level in BAL fluid and PB revealed downregulation in sarcoidosis and control groups. In PB lymphocytes, the statistically significant difference between patients and controls was observed (P = 0.003, Mann-Whitney U test), with higher expression in patients. There were no statistically significant differences between patients without and with parenchymal involvement (stages I vs. II-IV), between patients with acute vs. insidious onset of disease and between patients with abnormal vs. normal spirometry (P > 0.05, Mann-Whitney U test). Results suggest that expression of COX-2 mRNA in patients with pulmonary sarcoidosis is not related to clinical classifications.

Sarcoidosis: a Critical Review of History and Milestones

Sarcoidosis is a chronic systemic disease of unknown origin and uncertain prognosis that most commonly affects young adults, and frequently presents with bilateral hilar lymphadenopathy, pulmonary infiltrates and ocular and skin lesions. The diagnosis is established when characteristic clinical-radiological features are supported by compatible histopathology of epithelioid cell granulomas, following exclusion of known causes of granulomatous inflammation. Indeed, sarcoidosis belongs to a large family of disorders that share granuloma formation as common denominator. Since its first description by Jonathan Hutchinson in 1869, sarcoidosis has generated enormous interest and considerable controversy. In Hutchinson's day, it was considered a dermatological condition, which gradually evolved into a multisystem disorder associated in the majority of cases with respiratory abnormalities. With time, it has also become clear that sarcoidosis occurs throughout the world, affecting individuals of both genders and all races, although its prevalence varies widely across ethnic and racial groups. In recent years, advances in different disciplines, particularly biochemistry, genetics, immunology and molecular biology, have improved dramatically our understanding of the disease. Yet, the critical questions regarding who gets sarcoidosis and whether it has an infectious origin remain unanswered. Sarcoidosis has a distinguished medical history that covers the last 150 years. Right from the time of seminal contributions by Hutchinson, Besnier and Boeck medical discussion on sarcoidosis has always been animated and to a certain extent emotional. Such discussions will inevitable continue until the true cause of the disease has been found, hopefully in the near future.

Exhaled breath markers of alveolar macrophage activity in sarcoidosis

OBJECTIVE

Granuloma formation in sarcoidosis is dependent upon the interaction between alveolar macrophages (AMs) and a CD4+-driven TH1 response. This study aimed to measure TNF-α and calcium ion concentrations as markers of AM activity, in addition to total protein as a non-specific inflammatory marker in the exhaled breath condensate (EBC) of patients with sarcoidosis as well as control subjects.

METHODS

EBC was collected from 17 sarcoidosis patients and 23 healthy volunteers. Protein was measured by the bicinchoninic acid assay, TNF-α concentration was measured by ELISA and Ca(2+) concentration was measured by inductively coupled plasma-mass spectrometry. Conductivity of EBC was assessed using a conductivity probe.

RESULTS

Total protein concentration was significantly elevated in EBC from patients with sarcoidosis compared to control subjects (19.51 ± 4.52 vs. 10.60 ± 1.31 µg/ml, p = 0.020), as was TNF-α (3.37 ± 0.38 vs. 2.59 ± 0.40 pg/ml, p = 0.037) and conductivity (66.68 ± 16.73 vs. 36.85 ± 3.070 µS/cm, p = 0.044). EBC Ca(2+) concentration was significantly higher in healthy controls compared to patients with sarcoidosis (116.50 ± 12.19 vs. 73.88 ± 13.35 µmol/l, p = 0.018), although this was in the context of normal serum Ca(2+) in the sarcoidosis cohort.

CONCLUSIONS

Total protein and TNF-α concentrations were elevated in EBC from patients with sarcoidosis and could indicate disease activity. The reduction in EBC Ca(2+) concentrations could represent granulomatous activity in the lung.

The "mystery" of cutaneous sarcoidosis: facts and controversies

The reason why the cutaneous form of sarcoidosis is well known in the literature is because of its spectrum of manifestations granting it the fame of a Great Imitator. The mystery shrouding the pathogenesis of this rare cutaneous disease is still there (in spite of the fundamental progress of the various diagnostic methods in current day medicine). The production of the morphological substrate - the epithelioid cell granuloma - which is considered to be characteristic of skin sarcoidosis, could, however, also be the end result of a reaction to i) various specific infectious agents such as Leishmaniasis cutis, coccidioidomycosis, etc., ii) certain residual bacterial or other mycobacterial antigens which, at the moment of setting the diagnosis are - by definition - non-infectious but still immunogenic, as well as iii) different tumor antigens in lesional tissue or other location. Often, differentiating between sarcodiosis and a sarcoid-like reaction, based on the updated criteria for cutaneous sarcoidosis, is problematic to downright impossible. A future characterization of the genetic signature of the two conditions, as well as the implementation of additional mandatory panels for i) the identification of certain infectious or ii) non-infectious but immunogenic and iii) tumor antigens in the epithelioid cell granuloma (or in another location in the organism), could be a considerable contribution to the process of differentiating between the two above-mentioned conditions. This will create conditions for greater accuracy when setting the subsequent therapeutic approaches.

Cutaneous sarcoidosis: an intriguing model of immune dysregulation

Sarcoidosis is a systemic granulomatous disease characterized by the presence of non-caseating granulomas. Its etiology remains obscure. A plausible hypothesis suggests that a complex interplay of host factors, infectious processes, and non-infectious environmental factors, matched with a susceptible genetic background, results in a pathway that leads to systemic granulomatous inflammation. Although presentations of sarcoidosis vary enormously, multi-organ involvement is a common feature. Cutaneous involvement occurs in about 25% of patients with protean manifestations and variable prognoses. Skin manifestations are divided into specific lesions with histopathologically evident non-caseating granulomas and nonspecific lesions arising from a reactive process that does not form granulomas. A peculiar form of cutaneous sarcoidosis is represented by sarcoidal lesions at sites of trauma that has caused scarring. The pathogenesis of scar sarcoidosis remains unknown. Scar sarcoidosis is also associated with herpes zoster infection, surgery, and tattooing. Such heterogeneous events, along with those at the sites of chronic lymphedema, thermal burns, radiation dermatitis, and vaccinations, occur on areas of vulnerable skin labeled "immunocompromised districts". Numerous options are available for the treatment of cutaneous sarcoidosis. Although corticosteroids remain the treatment of choice for initial systemic therapy, other nonsteroidal agents have proven effective and therefore useful for long-term management. Tumor necrosis factor-α antagonists such as infliximab may have a role in the treatment of cutaneous sarcoidosis, especially in refractory cases that are resistant to standard regimens. Elucidation of the relationship of sarcoidal granulomas with malignancy and immunity may facilitate a better understanding of some pathomechanisms operating in neoplastic and immunity-related disorders.

A practical approach to cutaneous sarcoidosis

Sarcoidosis is a chronic inflammatory disorder that has the potential to affect multiple organs, including the skin. Its cutaneous manifestations are varied and can provide clues to underlying systemic manifestations. Unfortunately, they also can be disfiguring. Therapy is usually directed at the organ system most severely affected, which often may help cutaneous disease. However, cutaneous disease may be recalcitrant to treatment directed at extracutaneous disease, or it may be severe enough to require targeted therapy. This article focuses on the dermatologist's role in recognizing and diagnosing cutaneous sarcoidosis, evaluating patients for systemic disease involvement, and treating the skin manifestations of sarcoidosis.

Late-onset sarcoidosis in a patient with gastric mucosa-associated lymphoid tissue non-Hodgkin lymphoma: A case report

The simultaneous presence of hematological malignancies and sarcoidosis, defined as sarcoidosis-lymphoma syndrome, has been reported in 79 patients in the literature to date. The majority of these patients were affected by sarcoidosis and developed non-Hodgkin lymphoma or acute leukemia after 1–2 years; however, in <20 cases the malignancy developed first. This report presents the case of an 83-year-old male with a clinical history of Helicobacter pylori-positive gastric mucosa-associated lymphoid tissue lymphoma. The patient developed sarcoidosis 10 years after the first diagnosis, which caused the diagnostic work-up and differential diagnosis between a lymphoma relapse and de novo sarcoidosis to be challenging.

Endostatin and cathepsin-V in bronchoalveolar lavage fluid of patients with pulmonary sarcoidosis

Recently, it has been reported that lack of cathepsins prevent the development of lung granulomas in a mouse model of Besnier-Boeck-Schaumann (BBS) disease, sarcoidosis. There is no data about cathepsin V (Cath V) in bronchoalveolar lavage fluid (BALF) in humans. Endostatin is a novel inhibitor of lung epithelial cells. The role of this protein in BBS is not determined. The aim of this study was to evaluate the concentration of endostatin, Cath V, and IL-18 in BALF of BBS patients. We studied 22 BBS patients (Stage 2). The control group consisted of 20 healthy subjects. Cath V concentration was lower in BBS than in healthy group (16.03±8.60 vs. 32.25±21.90 pg/ml, p=0.004). Both endostatin and IL-18 levels were higher in BBS than in the control group (0.88±0.30 vs. 0.29±0.04 ng/ml, p=0.028; 40.37±31.60 vs. 14.61±1.30 pg/ml, p=0.007, respectively). In BBS there were correlations between the levels of endostatin and IL-18 (r=0.74, p=0.001) as well as endostatin and DLCO (diffusing capacity for carbon monoxide) (r=-0.6, p=0.013). Receiver-operating characteristic (ROC) curves were applied to find the cut-off for the BALF levels of Cath V, endostatin, and IL-18. We conclude that Cath V and endostatin may represent an index of pulmonary sarcoidosis activity.

Sarcoidosis: Immunopathogenesis and Immunological Markers

Sarcoidosis is a multisystem granulomatous disorder invariably affecting the lungs. It is a disease with noteworthy variations in clinical manifestation and disease outcome and has been described as an “immune paradox” with peripheral anergy despite exaggerated inflammation at disease sites. Despite extensive research, sarcoidosis remains a disease with undetermined aetiology. Current evidence supports the notion that the immune response in sarcoidosis is driven by a putative antigen in a genetically susceptible individual. Unfortunately, there currently exists no reliable biomarker to delineate the disease severity and prognosis. As such, the diagnosis of sarcoidosis remains a vexing clinical challenge. In this review, we outline the immunological features of sarcoidosis, discuss the evidence for and against various candidate etiological agents (infective and noninfective), describe the exhaled breath condensate, a novel method of identifying immunological biomarkers, and suggest other possible immunological biomarkers to better characterise the immunopathogenesis of sarcoidosis.

The sarcoid granuloma: 'epithelioid' or 'lymphocytic-epithelioid' granuloma?

Background

This study aims to analyze the structure and quantities of cellular elements in sarcoid granulomas.

Methods

We investigated 34 transbronchial lung biopsy samples obtained from 34 sarcoid patients. The quantity and composition of the cellular elements inside a granuloma were determined by the quantitative stereometry method, employing the numerical density as a stereological method.

Results

A total of 102 sarcoid granulomas were analyzed. The central part of all granulomas was occupied by epithelioid cells. Besides these, giant cells, lymphocytes, macrophages and plasma cells were also seen. The mean numerical density of all the cells in the central part of a sarcoid granuloma was 111,751 mm^-3. Lymphocytes prevailed in number, exceeding the total count of all other cells. With a mean numerical density of 74,321 mm^-3, lymphocytes were twice as numerous as both epithelioid cells and macrophages with a mean numerical density of 37,193 mm^-3.

Conclusions

Lymphocytes are the predominant cell type in the central part of a sarcoid granuloma, significantly exceeding both epithelioid cells and macrophages in number, raising the question if the term “epithelioid granuloma”, routinely used to designate sarcoid granulomas, is correct, or if it would be more logical to call them “lymphocytic-epithelioid granulomas” instead.

Trial registration

This study was supported by the Serbian Ministry of Science and Environmental Protection Grant Number 175006/2011.

Sarcoidosis and molecular mimicry--important etiopathogenetic aspects: current state and future directions

Sarcoidosis is a disease of uncertainty in terms of its cause, presentation, and clinical course. The disease has a worldwide distribution and affects all ages, races, and both sex. Sarcoidosis of the skin may have an extremely heterogeneous clinical presentation, so that the definitions of 'great imitator' and 'clinical chameleon' have long been used. The factors that influence clinical picture and severity of the disease are probably linked to the etiopathogenesis of sarcoidosis, which continues to be shrouded in mystery. The current state of the art on the pathogenesis of sarcoidosis is that it is an immunological response in a genetically susceptible individual to an as-yet undefined antigenic stimulus. How exposure occurs in genetically predisposed patients is not completely clear, but the most likely explanation is that these agents or antigens are either inhaled into the lungs or enter through contact with the skin, as these are the common target organs that are constantly in contact with the environment. An autoimmune etiology of sarcoidosis could possibly occur through a process of molecular mimicry of infectious or other environmental antigens to host antigens. This could lead to a cross-mediated immune response and induction of autoimmune disease. This molecular mimicry may probably be responsible for the heterogeneous clinical presentations of the disease. Several investigations and studies have provided valuable evidence on the etiopathogenesis of sarcoidosis, which may lead to the future development of targeted and innovative treatment strategies. Nevertheless, we are still a long way from unravelling the underlying cause of this mysterious disease.

Peripheral blood responses to specific antigens and CD28 in sarcoidosis

BACKGROUND

Potential antigens inducing sarcoid inflammation include mycobacterial and auto-antigens. Paradoxically, peripheral anergy to common recall antigens also occurs, possibly due to impaired dendritic cell or regulatory T-cell responses, or impaired T-cell co-stimulation. The purpose of this study was to compare peripheral blood responses of patients with sarcoidosis to candidate antigens, and examine CD28 T-cell co-stimulation.

METHODS

Peripheral blood mononuclear cell (PBMC) responses were examined from patients with sarcoidosis (n=16) and healthy control subjects (n=22) following PBMC stimulation with: anti-CD3/CD28 coated beads; Mycobacterium tuberculosis ESAT-6 and KatG peptides; vimentin and lysyl tRNA peptides; and common recall antigens, including cytomegalovirus (CMV) cell lysate as well as CMV, Epstein-Barr virus, influenza virus (CEF) peptides.

RESULTS

ESAT-6/KatG peptide stimulation induced greater numbers of IFN-γ producing T-cells, and elevated IL-2, IL-6 and TNF-α production in sarcoidosis compared to purified protein derivative (PPD)-negative healthy control subjects. PBMCs from patients with sarcoidosis showed reduced IFN-γ producing T-cells following stimulation with CMV lysate, CEF peptides and CD3/CD28 beads; and reduced IL-4 and TNF-α production following CD3/CD28 activation.

CONCLUSIONS

Patients with sarcoidosis exhibit greater PBMC responses to M. tuberculosis antigens compared to PPD-negative controls, but reduced T-cell responses to common recall antigens. One contributing mechanism may be impairment of T-cell CD28 co-stimulation.

Adaptive immune responses in primary cutaneous sarcoidosis

Sarcoidosis is a multisystemic inflammatory disorder with cutaneous lesions present in about one-quarter of the patients. Cutaneous lesions have been classified as specific and nonspecific, depending on the presence of nonnecrotizing epithelial cell granulomas on histologic studies. The development and progression of specific cutaneous sarcoidosis involves a complex interaction between cells of the adaptive immune systems, notably T-lymphocytes and dendritic cells. In this paper, we will discuss the role of T-cells and skin dendritic cells in the development of primary cutaneous sarcoidosis and comment on the potential antigenic stimuli that may account for the development of the immunological response. We will further explore the contributions of selected cytokines to the immunopathological process. The knowledge of the adaptive immunological mechanisms operative in cutaneous sarcoidosis may subsequently be useful for identifying prevention and treatment strategies of systemic sarcoidosis.

Regulatory T cells with reduced repressor capacities are extensively amplified in pulmonary sarcoid lesions and sustain granuloma formation

Sarcoidosis can evolve into a chronic disease with persistent granulomas accompanied by progressive fibrosis. While an unlimited inflammatory response suggests an impaired immune control in sarcoid lesions, it stands in contrast to the massive infiltration with CD4(+)CD25(high)FoxP3(+) regulatory T cells. We here revealed that those Treg cells in affected lung lesions were mainly derived from activated natural Treg cells with GARP (LRRC32)-positive phenotype but exhibited reduced repressor capacities despite high IL-10 and TGF-beta 1 levels. The repressive capacity of blood Treg cells, in contrast, was not impaired compared to age-matched healthy donors. Treg derived cells in granuloma lesions have undergone extensive rounds of amplifications indicated by shortened telomeres compared to blood Treg cells of the same patient. Lesional Treg derived cells moreover secreted pro-inflammatory cytokines including IL-4 which sustains granuloma formation through fibroblast amplification and the activation of mast cells, the latter indicated by the expression of membrane-bound oncostatin M.

Lack of cathepsin activities alter or prevent the development of lung granulomas in a mouse model of sarcoidosis

BACKGROUND

Remodeling of lung tissues during the process of granuloma formation requires significant restructuring of the extra-cellular matrix and cathepsins K, L and S are among the strongest extra-cellular matrix degrading enzymes. Cathepsin K is highly expressed in various pathological granulomatous infiltrates and all three enzymes in their active form are detected in bronchoalveolar lavage fluids from patients with sarcoidosis. Granulomatous inflammation is driven by T-cell response and cathepsins S and L are actively involved in the regulation of antigen presentation and T-cell selection. Here, we show that the disruption of the activities of cathepsins K, L, or S affects the development of lung granulomas in a mouse model of sarcoidosis.

METHODS

Apolipoprotein E-deficient mice lacking cathepsin K or L were fed Paigen diet for 16 weeks and lungs were analyzed and compared with their cathepsin-expressing littermates. The role of cathepsin S in the development of granulomas was evaluated using mice treated for 8 weeks with a potent and selective cathepsin S inhibitor.

RESULTS

When compared to wild-type litters, more cathepsin K-deficient mice had lung granulomas, but individually affected mice developed smaller granulomas that were present in lower numbers. The absence of cathepsin K increased the number of multinucleated giant cells and the collagen content in granulomas. Cathepsin L deficiency resulted in decreased size and number of lung granulomas. Apoe-/- mice treated with a selective cathepsin S inhibitor did not develop lung granulomas and only individual epithelioid cells were observed.

CONCLUSIONS

Cathepsin K deficiency affected mostly the occurrence and composition of lung granulomas, whereas cathepsin L deficiency significantly reduced their number and cathepsin S inhibition prevented the formation of granulomas.

Butyrophilin-like 2 in pulmonary sarcoidosis: a factor for susceptibility and progression?

The aims of this study were to assess the association of BTNL2G16071A with the course of pulmonary sarcoidosis and to verify the association with disease predisposition. In addition, the linkage between BTNL2G16071A and certain human leukocyte antigen (HLA)-DRB1/DQB1 types was investigated. In a retrospective case-control study BTNL2G16071A, HLA-DQB1, and HLA-DRB1 were typed in 632 sarcoidosis patients. These patients were classified into 304 patients with persistent sarcoidosis and 328 patients with nonpersistent sarcoidosis. The BTNL2 16071A variant allele was present significantly more often in patients with persistent disease (92.4%; 281/304) compared with patients demonstrating a nonpersistent course (86.6%; 284/328; odds ratio (OR) = 1.89 with 95% confidence interval (95% CI) 1.11-3.22). Furthermore, BTNL2 16071A variant allele carriers have an increased risk (OR = 1.85, 95% CI 1.19-2.88) of developing sarcoidosis. Moreover, the strong linkage between variant allele and HLA-DRB1*15 presence (OR = 8.43, 95% CI 3.02-23.5) was confirmed. The presence of a BTNL2G16071A variant allele almost doubles the risk of progressing to persistent pulmonary sarcoidosis in addition to increasing the risk of developing sarcoidosis. Presumably, these increased risks are caused by the strong linkage between BTNL2G16071A and DRB1*15. The choice between determining BTNL2G16071A SNP or the HLA-DRB1 type depends on the ability and/or availability to perform either test.

Dendritic cells in muscle lesions of sarcoidosis

Sarcoidosis is a chronic systemic granulomatous disorder of unknown etiology. The precise mechanism by which granulomatous lesions form is still obscure. Dendritic cells (DCs) are the most efficient antigen presenting cells; however, pathologic investigations of dendritic cells in the affected lesions of sarcoidosis are quite limited. We immunohistochemically examined the localization and phenotypes of dendritic cells and the expressions of CD40 and CD40L (CD154), which are key molecules in dendritic cell activation, in the muscles of 5 patients with muscular sarcoidosis, 8 patients with muscular disorders without inflammation, and 4 patients with histologically normal muscles as controls. In muscular sarcoidosis, CD1c-positive myeloid dendritic cells were scattered mainly in the lymphocyte layers of granulomas and the endomysium around the granulomas. Double immunostaining revealed that some CD1c-positive cells expressed the mature dendritic cell marker CD83, but immature dendritic cell marker CD1a-positive cells were not found. Smaller numbers of Blood dendritic cell antigen (BDCA)-2-positive plasmacytoid dendritic cells were found in the lymphocyte layers of granulomas. In the controls, small numbers of CD1c-positive cells were seen in the endomysium, whereas BDCA-2-positive cells were not observed except in 1 case. In muscular sarcoidosis, CD40 was expressed on mononuclear cells, on the interstitium around the muscle fibers and granulomas, and on the endothelium of vessels. CD40L was positive on mononuclear cells scattered within and around granulomas in 3 of 5 patients. In the controls, CD40 was expressed on the endothelium of the vessels and sparse mononuclear cells in the lesions of muscle fiber necrosis, whereas CD40L was not seen in any. In muscular sarcoidosis, recruitment of myeloid dendritic cells and less plasmacytoid dendritic cells and up-regulation of the CD40/CD40L system in affected muscles suggest that myeloid dendritic cells may be mainly involved in granulomatous inflammation through antigen presentation in a Th1 immune milieu.

Inflammatory diseases of the nasal cavities and paranasal sinuses

Inflammatory diseases of the nose and paranasal sinus are commonly encountered in diagnostic histopathology. This review describes the possible manifestations of the common diseases as well as highlighting some of the uncommon causes of sinonasal inflammation which may have importance for treatment and prognosis. The diagnosis of fungal sinusitis is primarily histological. It is important to distinguish between invasive and non-invasive fungal sinusitis, the latter including allergic fungal sinusitis characterized by 'allergic mucin' and scanty fungal hyphae. Nasal eosinophilia is a feature of both allergic and non-allergic rhinosinusitis and a wide range of secondary changes in inflammatory polyps may lead to diagnostic confusion. Nasal biopsies are often taken from perforations or inflammatory masses to confirm or exclude granulomatous diseases. There is a broad differential diagnosis for granulomatous sinonasal disease and pathologists should appreciate the diagnostic histological and clinical features of these conditions.

Significant CD4, CD8, and CD19 lymphopenia in peripheral blood of sarcoidosis patients correlates with severe disease manifestations

Background

Sarcoidosis is a poorly understood chronic inflammatory condition. Infiltration of affected organs by lymphocytes is characteristic of sarcoidosis, however previous reports suggest that circulating lymphocyte counts are low in some patients with the disease. The goal of this study was to evaluate lymphocyte subsets in peripheral blood in a cohort of sarcoidosis patients to determine the prevalence, severity, and clinical features associated with lymphopenia in major lymphocyte subsets.

Methodology/Principal Findings

Lymphocyte subsets in 28 sarcoid patients were analyzed using flow cytometry to determine the percentage of CD4, CD8, and CD19 positive cells. Greater than 50% of patients had abnormally low CD4, CD8, or CD19 counts (p<4×10⁻¹⁰). Lymphopenia was profound in some cases, and five of the patients had absolute CD4 counts below 200. CD4, CD8, and CD19 lymphocyte subset counts were significantly correlated (Spearman's rho 0.57, p = 0.0017), and 10 patients had low counts in all three subsets. Patients with severe organ system involvement including neurologic, cardiac, ocular, and advanced pulmonary disease had lower lymphocyte subset counts as a group than those patients with less severe manifestations (CD4 p = 0.0043, CD8 p = 0.026, CD19 p = 0.033). No significant relationships were observed between various medical therapies and lymphocyte counts, and lymphopenia was present in patients who were not receiving any medical therapy.

Conclusions/Significance

Significant lymphopenia involving CD4, CD8, and CD19 positive cells was common in sarcoidosis patients and correlated with disease severity. Our findings suggest that lymphopenia relates more to disease pathology than medical treatment.

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.

Protein levels of CC chemokine ligand (CCL)15, CCL16 and macrophage stimulating protein in patients with sarcoidosis

The objective of this study was to assess protein levels for candidate cytokines, chemokines, growth factors, matrix metalloproteinases and their inhibitors in bronchoalveolar lavage fluid (BALF) in patients with polar forms of pulmonary sarcoidosis, i.e. Löfgren's syndrome (LS) and more advanced chest X-ray (CXR) stage III disease. Twenty-four inflammatory molecules were analysed in unconcentrated BALF samples from 10 sarcoidosis patients with CXR stage III and 10 patients with LS by semiquantitative protein array. Four novel molecules [CC chemokine ligand (CCL)15, CCL16, macrophage migration inhibitory factor (MIF) and macrophage stimulating protein (MSP)], detected for the first time in association with sarcoidosis, were then quantified by enzyme-linked immunosorbent assay in a second cohort of 68 sarcoidosis patients and 17 control subjects. The protein levels of CCL15, CCL16, CCL24, CXCL8, CXCL9, CXCL10, interleukin-16, MIF, MSP and matrix metallopeptidase 1 were increased in CXR stage III patients when compared with patients with LS. CCL15 and MSP up-regulation in CXR stage III patients in comparison with LS patients and controls was confirmed by enzyme-linked immunosorbent assay. Moreover, MSP was associated with treatment requirement (P = 0.001) and CCL15 was elevated in patients with disease progression at 2-year follow-up (P = 0.016). CCL16 levels were increased in sarcoidosis versus controls (P < 0.05), but no difference was observed between patient subgroups. MIF up-regulation was not confirmed in a larger patient group. In conclusion, chemokines CCL15, CCL16 and MSP were found elevated for the first time in BALF from sarcoidosis patients; our results showed that CCL15 and MSP may affect disease course.

Hepatic, ocular, and cutaneous sarcoidosis

Sarcoid affecting the skin, eye, or liver can be symptomatic of or cause significant morbidity. When disease is sever, alternative therapies may be needed.