Genetics of Sarcoidosis

Concurrent features of sarcoidosis and hypersensitivity pneumonitis in two patients exposed to fungal antigens

BACKGROUND

Sarcoidosis and hypersensitivity pneumonitis (HP) are two distinct clinical entities that share granulomatous inflammation, although each of them has specific clinical, radiologic and pathologic profiles. Coexistence of the two diseases have been described, suggesting, at least in some cases, a common biologic background.

CASE PRESENTATION

We describe two patients showing the concurrent diagnosis of sarcoidosis and hypersensitivity pneumonitis. Case 1: a 51-year old never smoker man had a history of occupational exposure, episodes of acute exacerbations and positive serum precipitins to Penicillium spp suggestive of HP, while the positivity of serum angiotensin converting enzyme (ACE) favored sarcoidosis. Case 2: a 42-year old non-smoker woman with occasional finding of enlarged mediastinal lymph nodes had a history of domestic exposure to molds and positive serum precipitins to Aspergillus spp suggestive of HP. In both cases high resolution computed tomography (HRCT) together with broncoscopy findings allowed to maintain both the diagnoses: HRCT showed both enlarged hilar/mediastinal limph nodes and intersitial lung involvement typical of HP; bronchoalveolar lavage presented marked lymphocytosis and granulomatous nodal lesions were observed at transbronchial needle aspiration.

CONCLUSIONS

Sarcoidosis and HP share some clinical findings and the differential diagnosis may be difficult. Our cases suggest that a common trait may be responsible for the concurrent diagnosis of sarcoidosis and hypersensitivity pneumonitis in the same patient.

The Role of MRI in Differentiating Demyelinating and Inflammatory (not Infectious) Myelopathies

Demyelinating and inflammatory myelopathies represent a group of diseases with characteristic patterns in neuroimaging and several differential diagnoses. The main imaging patterns of demyelinating myelopathies (multiple sclerosis, neuromyelitis optica spectrum disorder, acute disseminated encephalomyelitis, and myelin oligodendrocyte glycoprotein antibody-related disorder) and inflammatory myelopathies (systemic lupus erythematosus-myelitis, sarcoidosis-myelitis, Sjögren-myelitis, and Behçet's-myelitis) will be discussed in this article, highlighting key points to the differential diagnosis.

Genome-wide association study identifies multiple HLA loci for sarcoidosis susceptibility

Sarcoidosis is a complex systemic disease. Our study aimed to (1) identify novel alleles associated with sarcoidosis susceptibility; (2) provide an in-depth evaluation of HLA alleles and sarcoidosis susceptibility and (3) integrate genetic and transcription data to identify risk loci that may more directly impact disease pathogenesis. We report a genome-wide association study of 1335 sarcoidosis cases and 1264 controls of European descent (EA) and investigate associated alleles in a study of African Americans (AA: 1487 cases and 1504 controls). The EA and AA cohort was recruited from multiple United States sites. HLA alleles were imputed and tested for association with sarcoidosis susceptibility. Expression quantitative locus and colocalization analysis were performed using a subset of subjects with transcriptome data. Forty-nine SNPs in the HLA region in HLA-DRA, -DRB9, -DRB5, -DQA1 and BRD2 genes were significantly associated with sarcoidosis susceptibility in EA, rs3129888 was also a risk variant for sarcoidosis in AA. Classical HLA alleles DRB1*0101, DQA1*0101 and DQB1*0501, which are highly correlated, were also associated with sarcoidosis. rs3135287 near HLA-DRA was associated with HLA-DRA expression in peripheral blood mononuclear cells and bronchoalveolar lavage from subjects and lung tissue and whole blood from GTEx. We identified six novel SNPs (out of the seven SNPs representing the 49 significant SNPs) and nine HLA alleles associated with sarcoidosis susceptibility in the largest EA population. We also replicated our findings in an AA population. Our study reiterates the potential role of antigen recognition and/or presentation HLA class II genes in sarcoidosis pathogenesis.

Evaluation of genetic risk, its clinical manifestation and disease management based on 18 susceptibility gene markers among West-Slavonic patients with sarcoidosis

Sarcoidosis is a heterogenous, multisystemic inflammatory disease that primarily affects lungs. In this study, we multiplex genotyped 18 single-nucleotide polymorphisms (SNPs) to replicate the findings from previous genome-wide association studies (GWAS) and candidate gene studies, and extended analyses to different clinical manifestations (Lofgren syndrome and chest X-ray [CXR] stages) including treatment response among West-Slavonic subjects (564 sarcoidosis patients and 301 healthy controls). We confirm the replication (with Bonferroni correction) of ANXA11 rs1049550 as protective variant for sarcoidosis (odds ratio [OR]=0.71, p=1.33×10^-3), non-LS (OR=0.66, p=2.71×10^-4) and CXR stages 2-4 (OR=0.62, p=7.48×10^-5) compared to controls in West-Slavonic population. We also validate the association of risk variants C6orf10 rs3129927 (OR=2.61, p=2.60×10^-8), TNFA rs1800629 (OR=1.56, p=6.65×10^-4), ATF6B rs3130288 (OR=2.75, p=1.06×10^-9) and HLA-DQA1 rs2187668 (OR=1.74, p=8.83×10^-4) with sarcoidosis compared to controls. For sub-phenotypes compared to controls, risk variants C6orf10 rs3129927 (OR=5.35, p=1.07×10^-12), TNFA rs1800629 (OR=2.66, p=5.94×10^-7), ATF6B rs3130288 (OR=5.24, p=5.21×10^-13), LRRC16A rs9295661 (OR=2.97, p=4.29×10^-4), HLA-DQA1 rs2187668 (OR=3.14, p=1.09×10^-6) and HLA-DRA rs3135394 (OR=5.23, p=8.25×10^-13) were associated with LS while C6orf10 rs3129927 (OR=1.96, p=4.27×10^-4) and ATF6B rs3130288 (OR=2.15, p=3.36×10^-5) were associated with non-LS. For CXR stages compared to controls, C6orf10 rs3129927 (OR=3.67, p=3.63×10^-11), TNFA rs1800629 (OR=1.84, p=1.32×10^-4), ATF6B rs3129927 (OR=3.63, p=1.82×10^-11), HLA-DQA1 rs2187668 (OR=2.13, p=9.59×10^-5) and HLA-DRA rs3135394 (OR=3.42, p=3.45×10^-10) were risk variants for early CXR stages 0-1 while C6orf10 rs3129927 (OR=1.99, p=5.51×10^-4), ATF6B rs3129927 (OR=2.23, p=3.52×10^-5) and HLA-DRA rs3135394 (OR=1.85, p=2.00×10^-3) were risk variants for advanced CXR stages 2-4. The present findings nominate gene variants as plausible prognostic markers for clinical phenotypes, treatment response and disease resolution/progression and may form the basis for establishing genotype-phenotype relationships in patients with sarcoidosis among West-Slavonic population.

Differentiating neurosarcoidosis from multiple sclerosis using combined analysis of basic CSF parameters and MRZ reaction

Background

Neurosarcodosis is one of the most frequent differential diagnoses of multiple sclerosis (MS) and requires central nervous system (CNS) biopsy to establish definite diagnosis according to the latest consensus diagnostic criteria. We here analyzed diagnostic values of basic cerebrospinal fluid (CSF) parameters to distinguish neurosarcoidosis from MS without CNS biopsy.

Methods

We retrospectively assessed clinical, radiological and laboratory data of 27 patients with neurosarcoidosis treated at our center and compared following CSF parameters with those of 138 patients with relapsing-remitting MS: CSF white cell count (WCC), CSF/serum albumin quotient (Q_alb), intrathecal production of immunoglobulins including oligoclonal bands (OCB), MRZ reaction, defined as a polyspecific intrathecal production of IgG reactive against ≥2 of 3 the viruses measles (M), rubella (R), and zoster (Z) virus, and CSF lactate levels. Additional inflammatory biomarkers in serum and/or CSF such as neopterin, soluble interleukin-2 receptor (sIL-2R) and C-reactive protein (CRP) were assessed.

Results

There was no significant difference in the frequency of CSF pleocytosis, but a CSF WCC > 30/μl was more frequent in patients with neurosarcoidosis. Compared to MS, patients with neurosarcoidosis showed more frequently an increased Q_alb and CSF lactate levels as well as increased serum and CSF levels of sIL-2R, but a lower frequency of intrathecal IgG synthesis and positive MRZ reaction. Positive likelihood ratio (PLR) of single CSF parameters indicating neurosarcoidosis was highest, if (a) CSF WCC was >30/μl (PLR 7.2), (b) Q_alb was >10 × 10^-3 (PLR 66.4), (c) CSF-specific OCB were absent (PLR 11.5), (d) CSF lactate was elevated (PLR 23.0) or (e) sIL-2R was elevated (PLR>8.0). The combination of (a) one of three following basic CSF parameters, i.e., (a.1.) CSF WCC >30/ul, or (a.2.) Q_Alb >10 × 10^-3, or (a.3.) absence of CSF-specific OCB, and (b) absence of positive MRZ reaction showed the best diagnostic accuracy (sensitivity and specificity each >92%; PLR 12.8 and NLR 0.08).

Conclusion

Combined evaluation of basic CSF parameters and MRZ reaction is powerful in differentiating neurosarcoidosis from MS, with moderate to severe pleocytosis and Q_Alb elevation and absence of intrathecal IgG synthesis as useful rule-in parameters and positive MRZ reaction as a rule-out parameter for neurosarcoidosis.

Factors associated with a diagnosis of sarcoidosis among US veterans of Iraq and Afghanistan

This study evaluated risk factors of sarcoidosis among Airborne Hazards and Open Burn Pit Registry (AHOBPR) participants using a retrospective age and sex-matched case-control design of AHOBPR participants deployed to Afghanistan or Southwest Asia with and without sarcoidosis diagnosed in the Veterans Health Administration (VHA). Logistic regression models tested for associations between sarcoidosis and self-reported cumulative deployment-related exposures. 661 Veterans (0.37%) were diagnosed with sarcoidosis in VHA. Logistic regression demonstrated lower odds of sarcoidosis in Hispanic participants (OR 0.08, CI 0.04-0.15) and those who served in the Navy (OR 0.40, CI 0.21-0.72). African American veterans (OR 2.27, CI 1.66-3.11) and former smokers (OR 1.87, CI 1.33-2.62) were at elevated risk. Of the exposure variables, convoy activities had the highest odds of being associated with sarcoidosis and was marginally statistically significant (OR 1.16, CI 1.00-1.35). Sarcoidosis was an uncommon diagnosis among AHOBPR participants and was associated with only one of eight assessed cumulative deployment-related exposures.

Genetics of neurosarcoidosis

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

Detection of Anti-Vimentin Antibodies in Patients with Sarcoidosis

There is a need to further characterize the antibody response to vimentin in relation to its possible involvement in pathogenicity of sarcoidosis and other lung disorders. Objectives: We investigated serum samples from patients with sarcoidosis, healthy controls and controls with other non-infectious lung diseases., to evaluate levels and frequency of these antibodies. Materials and methods: A retrospective-prospective comparative study was performed in the years 2015–2019. Sera from 93 patients with sarcoidosis, 55 patients with non-infectious lung diseases and 40 healthy subjects was examined for presence of autoantibodies to mutated citrullinated vimentin (anti-MCV). Patients with elevated anti-MCV levels were tested for antibodies to a cyclic citrullinated peptide (anti-CCP) and citrullinated vimentin (anti-Sa). In all cases ELISA assays was used. The results were considered statistically significant at p-value less than 0.05. Results of the study: The high concentrations of anti-MCV antibodies were more frequent in patients with sarcoidosis (40.9% of the cases, 38/93), compared to the control groups (23.6% and 25.0% of cases, respectively). In sarcoidosis, clinical symptoms similar to the autoimmune pathology were described. A moderate positive correlation between the anti-MCV and anti-Sa antibodies (r = 0.66) was found in 13 patients with sarcoidosis. There was no significant difference between the levels of the anti-MCV and the anti-CCP in patients with non-infectious lung diseases and the healthy control group. Conclusion: Antibodies to citrullinated cyclic peptides are not significant in the pathogenesis of sarcoidosis and other investigated pulmonary diseases (COPD, granulomatosis with polyangiitis, alveolitis) and based on their low concentration, it can be assumed that citrullination and modification of vimentin is not a key factor in the development of an autoimmune response in patients with sarcoidosis.

Occupational and environmental exposures in the Genomic Research in Alpha-1 Antitrypsin Deficiency and Sarcoidosis (GRADS) study

INTRODUCTION

Sarcoidosis is a granulomatous disorder thought to be caused by exposures in genetically susceptible individuals. This study investigated whether specific exposures were associated with different sarcoidosis phenotypes.

METHODS

Extensive demographic, occupational and environmental exposure data was analyzed from subjects enrolled in the NHLBI Genomic Research in Alpha-1 Antitrypsin Deficiency and Sarcoidosis (GRADS) study.

RESULTS

In patients with sarcoidosis, radiation exposure was significantly associated with an increased risk of cardiac sarcoidosis versus non-cardiac sarcoidosis. No exposures were significantly associated with pulmonary only disease versus extrapulmonary disease with or without pulmonary involvement, Scadding Stage II/III/IV versus Scadding Stage 0/I, acute or remitting disease versus non-acute or non-remitting disease, nor chronic versus non-chronic disease. Although not reaching statistically significance after adjustment for multiple comparisons, there were a number of exposures associated with specific disease phenotypes, including exposures where relationships to sarcoidosis have previously been described such as rural exposures and pesticide exposures.

CONCLUSIONS

Radiation exposure may be a risk factor for cardiac sarcoidosis. Other exposures may also be associated with specific phenotypes and should be further explored. The study was limited by small groups of exposed subjects for individual exposures and multiple comparisons. The development of novel and innovative exposure assessment tools is needed.

Novel HLA associations with outcomes of Mycobacterium tuberculosis exposure and sarcoidosis in individuals of African ancestry using nearest-neighbor feature selection

Tuberculosis and sarcoidosis are inflammatory diseases characterized by granulomas that may occur in any organ but are often found in the lung. The panoply of classical human leukocyte antigen (HLA) alleles associated with occurrence and/or severity of both diseases varies considerably across studies. This heterogeneity of results, due to variation in factors like ancestry and disease subphenotype, as well as the use of simple modeling strategies to elucidate likely complex relationships, has made conclusions about underlying commonalities difficult. Here we perform HLA association analyses in individuals of African ancestry, using a greater resolution to include subphenotypes of disease and employing more comprehensive analytical techniques. Using a novel application of nearest-neighbor feature selection to score allelic importance, we investigated HLA allele association with Mycobacterium tuberculosis exposure outcomes in the first analysis of both latent Mycobacterium tuberculosis infection and active disease compared with those who, despite long-term exposure to active index cases, have neither positive diagnostic tests nor display clinical symptoms. We also compared persistent to resolved sarcoidosis. This led to the identification of novel HLA associations and evidence of main effects and interaction effects. We found strikingly similar main effects and interaction effects at HLA-DRB1, -DQB1, and -DPB1 in those resistant to tuberculosis (either latent or active) and persistent sarcoidosis.

Small Fiber Neuropathy in Sarcoidosis

Sarcoidosis (SC) is a granulomatous disease of an unknown origin. The most common SC-related neurological complication is a small fiber neuropathy (SFN) that is often considered to be the result of chronic inflammation and remains significantly understudied. This study aimed to identify the clinical and histological correlates of small fiber neuropathy in sarcoidosis patients. The study was performed in 2018–2019 yy and included 50 patients with pulmonary sarcoidosis (n = 25) and healthy subjects (n = 25). For the clinical verification of the SFN, the “Small Fiber Neuropathy Screening List” (SFN-SL) was used. A punch biopsy of the skin was performed followed by enzyme immunoassay analysis with PGP 9.5 antibodies. Up to 60% of the sarcoidosis patients reported the presence of at least one complaint, and it was possible that these complaints were associated with SFN. The most frequent complaints included dysfunctions of the cardiovascular and musculoskeletal systems and the gastrointestinal tract. A negative, statistically significant correlation between the intraepidermal nerve fiber density (IEND) and SFN-SL score was revealed. In patients with pulmonary sarcoidosis, small fiber neuropathy might develop as a result of systemic immune-mediated inflammation. The most common symptoms of this complication were dysautonomia and mild sensory dysfunction.

Neurosarcoidosis: Pathophysiology, Diagnosis, and Treatment

Although often regarded as a protean illness with myriad clinical and imaging manifestations, neurosarcoidosis typically presents as recognizable syndromes that can be approached in a rational, systematic fashion. Understanding of neurosarcoidosis has progressed significantly in recent years, including updated diagnostic criteria and advances in treatment. The diagnosis of neurosarcoidosis is established by the clinical syndrome, imaging and histopathological findings, and exclusion of other causes. Mounting evidence supports the use of tumor necrosis factor inhibitors as an important addition to the therapeutic armamentarium, along with glucocorticoids and steroid-sparing cytotoxic immunosuppressants. In this narrative review, we summarize recent advances in the diagnosis and treatment of neurosarcoidosis.

Pure extra-thoracic sarcoidosis: about 24 cases

Introduction. Pure extra-thoracic sarcoidosis is rare and poorly characterized in the literature. Herein we present features of pure extra-thoracic sarcoidosis, in comparison with sarcoidosis with intra-thoracic involvement, in a population from the south of Tunisia. Methods. Retrospective, descriptive and comparative study of the patients presenting systemic sarcoidosis and attending the Department of Internal Medicine at the Hedi Chaker University Hospital, Sfax, Tunisia, for 21 years, from January 1996 to December 2016. Results. Twenty-four patients presented pure extra-thoracic sarcoidosis (30% of the cases of systemic sarcoidosis). There was a female predominance (79%). The mean age was 50 years. The main features were polyadenopathies (10 patients: 41.7%), cutaneous involvement (10 patients: 41.6%), inflammatory polyarthralgia (8 cases: 33.3%), general symptoms (6 patients: 25%), uveitis (6 cases: 25%), cholestasis (3 cases) and kidney involvement (2 cases). Lymphopenia, hypercalcemia, and hypercalciuria were observed each one in 12.5% of the cases, and high angiotensin converting enzyme (ACE) level in 38.5% of the cases. The histological proof was required in all the patients. Statistically significant associations identified were mainly hepatic involvement with general symptoms (p=0.035), peripheral lymphadenopathies (p=0.035) and kidney damage (p=0.022), and cutaneous involvement with articular manifestations (p=0.032). Systemic corticosteroids were used in half of the cases, with a good outcome in 21 cases, and recurrence in two cases. One patient was lost to follow up. The comparison to the form with mediastino-pulmonary involvement showed less lymphadenopathies (p=0.001), less lymphopenia (p=0.006), and less frequent use of corticosteroids (p=0.044). Conclusion. Our series was characterized by the frequency of the pure extra-thoracic form and the diversity of the systemic manifestations.

Retrospective study of elderly onset sarcoidosis in Tunisian patients

BACKGROUND

Sarcoidosis is a systemic granulomatous disease of unknown etiology. It affects mostly young adults. In the elderly, the presentation of this disease is different, often posing positive diagnosis problems.

OBJECTIVES

We intend to describe the various clinical features and the management of sarcoidosis in elderly patients (age ≥65 years) compared to the younger ones.

METHODS

We performed a retrospective, descriptive and comparative study in the Department of Internal Medicine in the University Hospital Hedi Chaker, Sfax, Tunisia, between 1996 and 2016.

RESULTS

From a series of 80 patients, we found sixteen patients (20%) with sarcoidosis diagnosed after the age of 65 years. A female preponderance (81,25%) was noted. Intrathoracic involvement concerned 13 patients (81,3%). Extrapulmonary signs were also frequent (93,8%). The main extrathoracic manifestations were ganglionar involvement (75%), an alteration of the general health (31,3%), hepatic involvement (31,3%), cutaneous involvement (25%) and ocular involvement (25%). Biological manifestations were hypercalcemia, hypercalciuria, lymphopenia and hypergammaglobulinemia noted in respectively 12,5%, 12,5%, 31,3% and 50% of the cases. Angiotensin-converting enzyme(ACE) level was elevated in 100% of the patients. Lymphadenopathy and cutaneous biopsies were important contributing factors to diagnosis (respectively: 100% and 75% were positive). Oral corticosteroid therapy was required in 50% of cases. Evolution was marked by pulmonary fibrosis in two cases. Satisfactory course of the disease was observed in the other patients.

CONCLUSION

Young and elderly subjects had common characteristics of sarcoidosis, except for more coexisting chronic morbidities, no erythema nodosum and more frequent high levels of ACE in the elderly group.

Histomorphological patterns of regional lymph nodes in COVID-19 lungs

BACKGROUND

A dysregulated immune response is considered one of the major factors leading to severe COVID-19. Previously described mechanisms include the development of a cytokine storm, missing immunoglobulin class switch, antibody-mediated enhancement, and aberrant antigen presentation.

OBJECTIVES

To understand the heterogeneity of immune response in COVID-19, a thorough investigation of histomorphological patterns in regional lymph nodes was performed.

MATERIALS AND METHODS

Lymph nodes from the cervical, mediastinal, and hilar regions were extracted from autopsies of patients with lethal COVID-19 (n = 20). Histomorphological characteristics, SARS-CoV‑2 qRT-PCR, and gene expression profiling on common genes involved in immunologic response were analyzed.

RESULTS

Lymph nodes displayed moderate to severe capillary stasis and edema, an increased presence of extrafollicular plasmablasts, mild to moderate plasmacytosis, a dominant population of CD8⁺ T‑cells, and CD11c/CD68⁺ histiocytosis with hemophagocytic activity. Out of 20 cases, 18 presented with hypoplastic or missing germinal centers with a decrease of follicular dendritic cells and follicular T‑helper cells. A positive viral load was detected by qRT-PCR in 14 of 20 cases, yet immunohistochemistry for SARS-CoV-2 N-antigen revealed positivity in sinus histiocytes of only one case. Gene expression analysis revealed an increased expression of STAT1, CD163, granzyme B, CD8A, MZB1, and PAK1, as well as CXCL9.

CONCLUSIONS

Taken together, our findings imply a dysregulated immune response in lethal COVID-19. The absence/hypoplasia of germinal centers and increased presence of plasmablasts implies a transient B‑cell response, implying an impaired development of long-term immunity against SARS-CoV‑2 in such occasions.

Whole genome sequencing identifies variants associated with sarcoidosis in a family with a high prevalence of sarcoidosis

Objective

We studied genetic risk factors associated with sarcoidosis within a family with a high prevalence of this disease.

Methods

We studied 41 members of a family with a high rate of sarcoidosis, including an index patient with treatment-resistant neurosarcoidosis. Whole genome sequencing was performed for six affected family members and variations associated with loss of function were filtered out as candidate genes. Findings were validated by using amplicon sequencing within all 41 family members with DNA available and candidate genes were screened on absence and presence within the sarcoidosis affected and non-affected.

Results

Family members (n = 61) from 5 generations were available for participation including 13 subjects diagnosed with sarcoidosis (20%). Analyses identified 36 candidate variants within 34 candidate genes. Variations within three of these genes (JAK2, BACH2, and NCF1) previously have been associated with autoimmune diseases.

Conclusions

We identified 34 genes with a possible role in the etiology of sarcoidosis, including JAK2. Our results may suggest evaluation of JAK inhibitors in treatment-resistant sarcoidosis.

Key Points • JAK2 has a potential role in the etiology of sarcoidosis and is a potential therapeutic target. • We identified 33 additional candidate genes of which BACH2 and NCF1 have been previously associated with autoimmune disease.

Supplementary Information

The online version contains supplementary material available at 10.1007/s10067-021-05684-w.

Adalimumab-induced sarcoidosis-like reaction involving oral cavity in rheumatoid arthritis: a case-based review

Drug-induced sarcoidosis-like reaction (DISR) is a condition almost indistinguishable from sarcoidosis, both clinically and microscopically, consisting of granulomatous tissue reaction associated with a specific therapy. Commonly affected sites are the lungs, hilar lymph nodes, and skin. This report aimed to describe a very uncommon case of DISR with an unique involvement of the oral cavity. A 63-year-old female with a history of rheumatoid arthritis, who was treated with a TNF-α antagonist (adalimumab), presented multiple ulcerative nodules on the hard palate. Laboratory tests and imaging studies failed to show any other alterations. The biopsy specimen demonstrated multiple noncaseating granulomas. Histochemical reactions were negative for acid-fast bacilli and fungi, and immunohistochemical assessment highlighted the presence of normal lymphocytes and histiocytes. With the diagnosis of DISR, adalimumab was discontinued, and complete clinical resolution of the lesions was achieved after 14 months. Although uncommon, DISR should be considered in differential diagnoses of oral granulomatous reactions, especially in cases where the patient is being treated with TNF-α antagonists.

[Histomorphological patterns of regional lymph nodes in COVID-19 lungs]

Hintergrund

Eine dysregulierte Immunantwort, z. B. in der Form eines Zytokinsturmes, einer Störung des Immunglobulinklassenwechsels, eines sog. antikörpervermitteltem Enhancements oder einer aberranten Antigenpräsentation wurde bereits in schweren Krankheitsverläufen von COVID-19 beschrieben.

Ziel der Arbeit

Zur Charakterisierung der COVID-19-Immunantwort wurde die Histomorphologie der Lymphknoten des pulmonalen Abflussgebietes untersucht.

Material und Methoden

Regionale Lymphknoten des pulmonalen Abflussgebiets wurden bei COVID-19-Autopsien asserviert (n = 20). Deren Histomorphologie, SARS-CoV-2-qRT-PCR sowie Genexpressionsanalysen von gängigen Genen der Immunantwort wurden berücksichtigt.

Ergebnisse

Histologisch zeigten sich ein mäßig- bis schwergradiges Ödem mit Kapillarostase, eine erhöhte Anzahl von extrafollikulären Plasmablasten, milde bis mäßige Plasmazytose, vermehrte CD8⁺-T-Zellen und CD11c/CD68⁺-Histiozyten mit Hämophagozytoseaktivität. Von 20 Fällen wiesen 18 hypoplastische oder fehlende Keimzentren sowie eine Verminderung der follikulären dendritischen Zellen und follikulären T‑Helferzellen auf. In 14 von 20 Fällen war der qRT-PCR-Nachweis von SARS-CoV‑2 positiv, jedoch zeigte sich nur bei einem einzigen Fall eine immunhistochemische Positivität für SARS-CoV-2-N-Antigene in Sinushistiozyten. In Genexpressionsanalysen war eine erhöhte Expression von STAT1, CD163, Granzym B, CD8A, MZB1 und PAK1, neben CXCL9 zu beobachten.

Diskussion

Die Befunde in den Lymphknoten deuten auf eine dysregulierte Immunantwort bei schweren COVID-19-Krankheitsverläufen hin. Insbesondere impliziert das Ausbleiben der Keimzentrumsreaktion und die vermehrte Präsenz von Plasmablasten eine nur transiente B‑Zellreaktion, welche die Entwicklung einer Langzeitimmunität infrage stellt.

Classical Examples of the Concept of the ASIA Syndrome

Autoimmune/inflammatory syndrome induced by adjuvants (ASIA) was first introduced in 2011 by Shoenfeld et al. and encompasses a cluster of related immune mediated diseases, which develop among genetically prone individuals as a result of adjuvant agent exposure. Since the recognition of ASIA syndrome, more than 4400 documented cases have been reported so far, illustrated by heterogeneous clinical manifestations and severity. In this review, five enigmatic conditions, including sarcoidosis, Sjögren's syndrome, undifferentiated connective tissue disease, silicone implant incompatibility syndrome (SIIS), and immune-related adverse events (irAEs), are defined as classical examples of ASIA. Certainly, these disorders have been described after an adjuvant stimulus (silicone implantation, drugs, infections, metals, vaccines, etc.) among genetically predisposed individuals (mainly the HLA-DRB1 and PTPN22 gene), which induce an hyperstimulation of the immune system resulting in the production of autoantibodies, eventually leading to the development of autoimmune diseases. Circulating autonomic autoantibodies in the sera of patients with silicone breast implants, as well as anatomopathological aspects of small fiber neuropathy in their skin biopsies have been recently described. To our knowledge, these novel insights serve as a common explanation to the non-specific clinical manifestations reported in patients with ASIA, leading to the redefinition of the ASIA syndrome diagnostic criteria.

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

PURPOSE OF REVIEW

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

RECENT FINDINGS

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

SUMMARY

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

Models Contribution to the Understanding of Sarcoidosis Pathogenesis: "Are There Good Models of Sarcoidosis?"

Sarcoidosis is a systemic, granulomatous, and noninfectious disease of unknown etiology. The clinical heterogeneity of the disease (targeted tissue(s), course of the disease, and therapy response) supports the idea that a multiplicity of trigger antigens may be involved. The pathogenesis of sarcoidosis is not yet completely understood, although in recent years, considerable efforts were put to develop novel experimental research models of sarcoidosis. In particular, sarcoidosis patient cells were used within in vitro 3D models to study their characteristics compared to control patients. Likewise, a series of transgenic mouse models were developed to highlight the role of particular signaling pathways in granuloma formation and persistence. The purpose of this review is to put in perspective the contributions of the most recent models in the understanding of sarcoidosis.

Cutaneous Sarcoidosis

Sarcoidosis is a chronic, multisystem, inflammatory disorder of unknown etiology that is characterized by noncaseating granulomas that impair normal organ functioning. Sarcoidosis predominantly affects the lungs, but the skin is often cited as the second most frequently involved organ. Cutaneous manifestations of sarcoidosis are highly variable and ongoing research seeks to better understand the relationship between clinical morphology and disease prognosis. Skin findings in patients with sarcoidosis can be "specific," in which sarcoidal granulomas infiltrate the skin, or they can represent a "nonspecific" reactive inflammatory process, as is seen in calcinosis cutis and erythema nodosum. Cutaneous sarcoidosis can be the initial presenting sign or develop later in the course of the disease. In some patients, the skin will be the most involved and impactful organ system and will drive therapy. In other cases, the skin will be an incidental or minor finding, but may be easily accessible for biopsy to confirm the diagnosis. There are many potential therapies for sarcoidosis, though no one therapy is universally effective.

Sicca syndrome following immune checkpoint inhibition

The recent approval of Immunologic checkpoint inhibitors as an effective therapeutic strategy against cancer came at the cost of toxicities mediated by an excessive activation of immune system against health tissues, including among others musculoskeletal and sicca complaints.The latter occur in the context of an entity reminiscent of Sjogren's syndrome, with distinct characteristics such as abrupt onset, male predominance, lower prevalence of autoantibodies and response to steroids.

Sex-Based Differences in Interstitial Lung Disease

Interstitial lung diseases comprise a family of progressive pulmonary disorders that are often idiopathic or associated with various systemic diseases and that is characterized by bilateral lung involvement with inflammation and tissue remodeling or fibrosis. The impact of sex, including the anatomic and physiologic traits that one is born with, on the development and progression of interstitial lung diseases is not entirely clear. Variances between men and women are driven by differences in male and female biology and sex hormones, among other differences, but their role remains uncertain. In this review, we summarize sex-related differences in the epidemiology and progression of certain interstitial lung diseases with a focus on the connective tissue related interstitial lung diseases, idiopathic pulmonary fibrosis, and sarcoidosis. We also discuss cellular and pre-clinical studies that might shed light on the potential mechanisms responsible for these differences in the hope of unveiling potential targets for intervention and stimulating research in this needed field of investigation.

Sarcoidosis as an Autoimmune Disease

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

Genetic Basis of Myocarditis: Myth or Reality?

The genetic basis of myocarditis remains an intriguing concept, at least as long as the definition of myocarditis constitutes the definitive presence of myocardial inflammation sufficient to cause the observed ventricular dysfunction in the setting of cardiotropic infections. Autoimmune or immune-mediated myocardial inflammation constitutes a complex area of clinical interest, wherein numerous and not yet fully understood role of hereditary auto-inflammatory diseases can result in inflammation of the pericardium and myocardium. Finally, myocardial involvement in hereditary immunodeficiency diseases, cellular and humoral, is a possible trigger for infections which may complicate the diseases themselves. Whether the role of constitutional genetics can make the patient susceptible to myocardial inflammation remains yet to be explored.

Clustering of immune-mediated diseases in sarcoidosis

PURPOSE OF REVIEW

Sarcoidosis is an immune-mediated disease of unknown cause. Immune-mediated diseases appear to cluster in patients and in families. We review what is known on this topic for sarcoidosis, and what factors may underlie disease clustering.

RECENT FINDINGS

In populations of patients with sarcoidosis, relative risk estimates of Sjögren's syndrome, systemic lupus erythematosus, autoimmune hepatitis, ankylosing spondylitis, multiple sclerosis (MS), celiac disease, autoimmune thyroid disease, and ulcerative colitis, varied between 2.1 and 11.6. In relatives of patients with sarcoidosis, relative risk estimates varied between 1.3 and 5.8 for sarcoidosis, MS, celiac disease, type 1 diabetes, Graves' disease, rheumatoid arthritis, Crohn's disease, and ulcerative colitis. Shared risk loci in key immunological pathways provide evidence for a contribution to development of multiple diseases. Identical changes in the immune status, epigenetic alterations, and environmental triggers have been detected in several diseases, and drug-induced disease is likely responsible for a small portion of co-occurring disease.

SUMMARY

Clustering of sarcoidosis and other immune-mediated diseases in patients and in their relatives occurs for sarcoidosis, MS, celiac disease, Graves' disease, and ulcerative colitis. Further research is needed to substantiate causal links and risk estimates in patients and their relatives.

Host-microbe interactions in the pathogenesis and clinical course of sarcoidosis

Sarcoidosis is a rare inflammatory disease characterized by the development of granulomas in various organs, especially in the lungs and lymph nodes. Clinics of the disease largely depends on the organ involved and may range from mild symptoms to life threatening manifestations. Over the last two decades, significant advances in the diagnosis, clinical assessment and treatment of sarcoidosis have been achieved, however, the precise etiology of this disease remains unknown. Current evidence suggests that, in genetically predisposed individuals, an excessive immune response to unknown antigen/s is crucial for the development of sarcoidosis. Epidemiological and microbiological studies suggest that, at least in a fraction of patients, microbes or their products may trigger the immune response leading to sarcoid granuloma formation. In this article, we discuss the scientific evidence on the interaction of microbes with immune cells that may be implicated in the immunopathogenesis of sarcoidosis, and highlight recent studies exploring potential implications of human microbiota in the pathogenesis and the clinical course of sarcoidosis.

Sarcoidosis

Sarcoidosis is a multisystemic granulomatous disease that affects individuals worldwide. The lungs are most commonly involved but any organ can be involved. It has variable manifestations and clinical course. Diagnosis of sarcoidosis is based on clinicopathologic findings and the exclusion of other causes of granulomatous disease. Its hallmark is the formation of granulomas in affected organs. Immunosuppressive therapy is the cornerstone of the management of sarcoidosis and is indicated when there is evidence of symptomatic or progressive disease or when critical organs (ocular, cardiac, nervous system) are involved.

Microbial Lineages in Sarcoidosis. A Metagenomic Analysis Tailored for Low-Microbial Content Samples

RATIONALE

The etiology of sarcoidosis is unknown, but microbial agents are suspected as triggers.

OBJECTIVES

We sought to identify bacterial, fungal, or viral lineages in specimens from patients with sarcoidosis enriched relative to control subjects using metagenomic DNA sequencing. Because DNA from environmental contamination contributes disproportionately to samples with low authentic microbial content, we developed improved methods for filtering environmental contamination.

METHODS

We analyzed specimens from subjects with sarcoidosis (n = 93), control subjects without sarcoidosis (n = 72), and various environmental controls (n = 150). Sarcoidosis specimens consisted of two independent sets of formalin-fixed, paraffin-embedded lymph node biopsies, BAL, Kveim reagent, and fresh granulomatous spleen from a patient with sarcoidosis. All specimens were analyzed by bacterial 16S and fungal internal transcribed spacer ribosomal RNA gene sequencing. In addition, BAL was analyzed by shotgun sequencing of fractions enriched for viral particles, and Kveim and spleen were subjected to whole-genome shotgun sequencing.

MEASUREMENTS AND MAIN RESULTS

In one tissue set, fungi in the Cladosporiaceae family were enriched in sarcoidosis compared with nonsarcoidosis tissues; in the other tissue set, we detected enrichment of several bacterial lineages in sarcoidosis but not Cladosporiaceae. BAL showed limited enrichment of Aspergillus fungi. Several microbial lineages were detected in Kveim and spleen, including Cladosporium. No microbial lineage was enriched in more than one sample type after correction for multiple comparisons.

CONCLUSIONS

Metagenomic sequencing revealed enrichment of microbes in single types of sarcoidosis samples but limited concordance across sample types. Statistical analysis accounting for environmental contamination was essential to avoiding false positives.

Next-Generation Sequencing Based HLA Typing: Deciphering Immunogenetic Aspects of Sarcoidosis

Unraveling of the HLA-related immunogenetic basis of several immune disorders is complex due to the extensive HLA polymorphism and strong linkage-disequilibrium between HLA loci. A lack of in phase sequence information, a relative deficiency of high resolution genotyping including non-coding regions and ambiguous haplotype assignment make it difficult to compare findings across association studies and to attribute a causal role to specific HLA alleles/haplotypes in disease susceptibility and modification of disease phenotypes. Earlier, historical antibody and DNA-based methods of HLA typing, primarily of low resolution at antigen/alellic group levels, yielded "indicative" findings which were partially improved by high-resolution DNA-based typing. Only recently, next-generation sequencing (NGS) approaches based on deep-sequencing of the complete HLA genes combined with bioinformatics tools began to provide the access to complete information at an allelic level. Analyzing HLA with NGS approaches, therefore, promises to provide further insight in the etiopathogenesis of several immune disorders in which HLA associations have been implicated. These range from coeliac disease and rheumatological conditions to even more complex disorders, such as type-1 diabetes, systemic lupus erythematosus and sarcoidosis. A systemic disease of unknown etiology, sarcoidosis has previously been associated with numerous HLA variants and also other gene polymorphisms, often in linkage with the HLA region. To date, the biological significance of these associations has only partially been defined. Therefore, more precise assignments of HLA alleles/haplotypes using NGS approaches could help to elucidate the exact role of HLA variation in the multifaceted etiopathogenesis of sarcoidosis, including epigenetic mechanisms. NGS-based HLA analyses may be also relevant for defining variable clinical phenotypes and for predicting the disease course or the response to current/plausible novel therapies.

Executive Summary of the NHLBI Workshop Report: Leveraging Current Scientific Advancements to Understand Sarcoidosis Variability and Improve Outcomes

Sarcoidosis is a systemic granulomatous disease that primarily affects the lung; it is associated with significant disparities, more commonly impacting those in the prime of their lives (age 20-50 yr, with a second peak after age 60 yr), black individuals, and women. However, the burden of disease, the ability to diagnose and prognose organ involvement and course, as well as specific treatment options, management options, and disease pathogenesis remain poorly understood. As a result, the National Heart, Lung, and Blood Institute undertook a sarcoidosis workshop, "Leveraging Current Scientific Advancements to Understand Sarcoidosis Variability and Improve Outcomes," to help address these issues by defining the scientific and clinical priorities to improve sarcoidosis care. The overarching recommendations from this workshop are outlined in the following summary and detailed in the accompanying articles. The recommendations included establishing collaborations and networks to conduct research based on consensus definitions of disease phenotypes and standards of care, and to provide clinical outreach to areas with a burden of disease to improve care. These collaborative networks would also serve as the hub to conduct clinical trials of devastating phenotypes (e.g., cardiac, neurologic, and fibrotic disease) not only for treatment but to enhance our understanding of the burden of disease. In addition, the networks would be used to leverage state-of-the-art "omics" and systems biology research, as well as other studies to advance understanding of disease pathogenesis, and development of biomarkers and therapeutic targets, with a goal to translate this information to improve care of individuals with sarcoidosis.

Management of chronic ocular sarcoidosis: challenges and solutions

Background

Sarcoidosis constitutes one of the leading causes of ocular inflammation. Chronic ocular sarcoidosis can affect any segment of the eye and its adnexa, producing a wide range of clinical manifestations and severity. If left untreated, permanent visual impairment or even blindness may ensue. Treatment approaches vary from topical therapy to systemic agents that induce immunosuppression to different levels according to disease severity.

Objective

To review the published literature on the management options for chronic ocular sarcoidosis and provide a comprehensive list of available treatment strategies, including the newer biologics.

Summary

Ocular disease remains a challenging aspect of sarcoidosis and may even be the presenting sign of the disease. Prompt and effective therapy may reverse visual damage and prevent permanent loss of vision. Because of the complexity of the disease, a multidisciplinary approach is often required, with a view to addressing both the ocular and other systemic manifestations of sarcoidosis. Recent data suggest that achieving overall optimal systemic control is of paramount importance in controlling eye inflammation as well. Cytotoxic immunosuppressive agents for refractory chronic ocular disease, as well as biologic anti-TNFα therapies, have advanced the management of chronic disease and should be considered corticosteroid-sparing strategies before the onset of significant steroid-induced morbidity.

Association of class II human leukocyte antigen (HLA) alleles with pulmonary sarcoidosis

Background and objectives: Sarcoidosis is a systemic inflammatory disease of unknown etiology that involves any part of the body, mainly the lungs and thoracic lymph nodes. The clinical presentation is heterogeneous based on the degree and extent of organ involvement. The existence of variable clinical presentations and treatment responses suggest an important role of genetic predisposition. In genetic studies, sarcoidosis was found to be associated with several genes, but the strongest link was with HLA region. The aim of this study was to investigate the association of HLA class II alleles with the extent and course of disease in Turkish patients with sarcoidosis. Methods: The study included 103 patients with sarcoidosis and 100 unrelated healthy controls. HLA-DRB1 and HLA-DQB1 typing was performed by using Polymerase Chain Reaction-Sequence Specific Priming (PCR-SSP) method at low resolution level. Results: HLA-DRB1* and -DQB1* analysis revealed that while the frequency of HLA-DRB1*01 was significantly higher in the control group, HLA-DRB1*13 and -DQB1*06 alleles were more frequent in the sarcoidosis patients. When the patients were grouped based on clinical outcome as remitters and non-remitters, HLA-DRB1*10 allele was only detected in the remitters, whereas the frequency of HLA-DQB1*06 allele was significantly higher in non-remitters. Conclusions: This study supported the association of HLA alleles with sarcoidosis. In a considerably high number of patients with Turkish origin, the frequency of HLA-DRB1*13, -DRB1*10 and HLA-DQB1*06 alleles was significantly associated with increased risk and clinical outcome. (Sarcoidosis Vasc Diffuse Lung Dis 2018; 35: 143-149).

Infliximab for the treatment of CNS sarcoidosis: A multi-institutional series

OBJECTIVE

To describe clinical and imaging responses in neurosarcoidosis to infliximab, a monoclonal antibody against tumor necrosis factor-α.

METHODS

Investigators at 6 US centers retrospectively identified patients with CNS sarcoidosis treated with infliximab, including only patients with definite or probable neurosarcoidosis following rigorous exclusion of other causes.

RESULTS

Of 66 patients with CNS sarcoidosis (27 definite, 39 probable) treated with infliximab for a median of 1.5 years, the mean age was 47.5 years at infliximab initiation (SD 11.7, range 24-71 years); 56.1% were female; 62.1% were white, 37.0% African American, and 3% Hispanic. Sarcoidosis was isolated to the CNS in 19.7%. Using infliximab doses ranging from 3 to 7 mg/kg every 4-8 weeks, MRI evidence of a favorable treatment response was observed in 82.1% of patients with imaging follow-up (n = 56), with complete remission of active disease in 51.8% and partial MRI improvement in 30.1%; MRI worsened in 1 patient (1.8%). There was clinical improvement in 77.3% of patients, with complete neurologic recovery in 28.8%, partial improvement in 48.5%, clinical stability in 18.2%, worsening in 3%, and 1 lost to follow-up. In 16 patients in remission when infliximab was discontinued, the disease recurred in 9 (56%), typically in the same neuroanatomic location.

CONCLUSIONS

Most patients with CNS sarcoidosis treated with infliximab exhibit favorable imaging and clinical treatment responses, including some previously refractory to other immunosuppressive treatments.

CLASSIFICATION OF EVIDENCE

This study provides Class IV evidence that for patients with CNS sarcoidosis infliximab is associated with favorable imaging and clinical responses.

The role of serum amyloid A staining of granulomatous tissues for the diagnosis of sarcoidosis

BACKGROUND

Previous studies demonstrated that SAA staining of sarcoidosis granulomas was qualitatively and quantitatively different from other granulomatous diseases. These data suggest that positive SAA staining of granulomatous tissue may have adequate specificity to establish a diagnosis of sarcoidosis. Our objective was to determine the diagnostic specificity of SAA staining for sarcoidosis relative to other granulomatous disorders.

METHODS

Pathological specimens demonstrating granulomatous inflammation were retrospectively identified at one institution, plus 4 specimens were obtained from New York City firefighters with biopsy-confirmed World Trade Center "sarcoidosis-like" pulmonary disease. Specimens were analyzed if specific diagnoses related to the granulomatous inflammation were confirmed through medical record review. SAA staining was performed using previously developed methods. Two pathologists, blinded to each other and the diagnoses, determined if the stained material was SAA positive or negative. Discordant results were adjudicated by the two pathologists.

MEASUREMENTS AND MAIN RESULTS

106 specimens were analyzed from 100 patients, with 36 biopsies (34%) from sarcoidosis tissues and 70 (66%) from other granulomatous disorders. The Cohen Kappa correlation between the two pathologists for SAA staining positivity was excellent (0.85, 0.73-0.98). The overall specificity of SAA staining for the diagnosis of sarcoidosis was 84% (59/70). The sensitivity was 44% (16/36).

CONCLUSIONS

Although SAA staining of various granulomatous tissues was fairly specific for the diagnosis of sarcoidosis, the specificity was inadequate for SAA staining to be used as a diagnostic test for sarcoidosis in isolation. These data suggest that SAA production may not be a universal mechanism in the development of sarcoidosis.

Sarcoidosis: an update on current pharmacotherapy options and future directions

INTRODUCTION

Sarcoidosis is a systemic disease of unknown etiology characterized by the development of non-caseating epitheloid granulomas. The lungs are the most commonly involved organ (>90% of cases), followed by the lymph nodes, the skin, and the eyes. Areas covered: This review summarizes current pharmacotherapy options and future directions for the development of new therapies. Glucocorticoids are the first-line therapy for sarcoidosis. For patients with the most severe forms of sarcoidosis (who will need glucocorticoids for long periods) and for those intolerant or refractory, immunosuppressive drugs are used as sparing agents. The management of extrathoracic sarcoidosis must be tailored to the specific organ or organs involved; however, there is limited data from controlled trials to guide the treatment of these patients. The emergence of biological therapies has increased the therapeutic armamentarium available to treat sarcoidosis, with monoclonal anti-TNF agents being the most promising, but their use is still limited by a lack of licensing and costs. Expert commentary: The treatment of sarcoidosis is still not totally standardized. New effective therapies are urgently needed to enable the reduction or replacement of long-term therapy with glucocorticoids in patients with sarcoidosis.

High throughput 16SrRNA gene sequencing reveals the correlation between Propionibacterium acnes and sarcoidosis

Objective

This study aims to use high throughput 16SrRNA gene sequencing to examine the bacterial profile of lymph node biopsy samples of patients with sarcoidosis and to further verify the association between Propionibacterium acnes (P. acnes) and sarcoidosis.

Methods

A total of 36 mediastinal lymph node biopsy specimens were collected from 17 cases of sarcoidosis, 8 tuberculosis (TB group), and 11 non-infectious lung diseases (control group). The V4 region of the bacterial 16SrRNA gene in the specimens was amplified and sequenced using the high throughput sequencing platform MiSeq, and bacterial profile was established. The data analysis software QIIME and Metastats were used to compare bacterial relative abundance in the three patient groups.

Results

Overall, 545 genera were identified; 38 showed significantly lower and 29 had significantly higher relative abundance in the sarcoidosis group than in the TB and control groups (P < 0.01). P. acnes 16SrRNA was exclusively found in all the 17 samples of the sarcoidosis group, whereas was not detected in the TB and control groups. The relative abundance of P. acnes in the sarcoidosis group (0.16% ± 0. 11%) was significantly higher than that in the TB (Metastats analysis: P = 0.0010, q = 0.0044) and control groups (Metastats analysis: P = 0.0010, q = 0.0038). The relative abundance of P. granulosum was only 0.0022% ± 0. 0044% in the sarcoidosis group. P. granulosum 16SrRNA was not detected in the other two groups.

Conclusion

High throughput 16SrRNA gene sequencing appears to be a useful tool to investigate the bacterial profile of sarcoidosis specimens. The results suggest that P. acnes may be involved in sarcoidosis development.

Electronic supplementary material

The online version of this article (doi:10.1186/s12931-017-0515-z) contains supplementary material, which is available to authorized users.