Presence of Propionibacterium acnes in granulomas associates with a chronic disease course in Dutch sarcoidosis patients

Biomarkers in Sarcoidosis: Beginning of a New Era?

At present, no biomarker exists which is truly specific for sarcoidosis and the ones available have modest sensitivity and specificity. The clinical context should dictate the choice of biomarker(s) used to address different clinical questions such as diagnosis, monitoring disease activity or monitoring response to treatment. In the future, in addition to known serum biomarkers, it seems fruitful to further explore a possible role of imaging, exhaled air and even biopsy-related biomarkers in sarcoidosis to guide clinical management.

Frontal cutaneous and bone sarcoidosis: an example of the contiguous spread of granulomas

Sarcoidosis is a multisystemic granulomatous disease of unknown origin. It has been argued that the skin is one of the entry doors of the possible antigen that causes sarcoidosis and after entering the skin, the causal agent may progress to the underlying bone. We report four cases with development of sarcoidosis in old scars located on the forehead, and contiguous bone involvement of the frontal bone. In most cases scar sarcoidosis was the first manifestation of the disease, and in most cases it was asymptomatic. Two patients never required treatment, and in all cases the frontal problem improved or remained stable spontaneously or under sarcoidosis treatment. Scar sarcoidosis in the frontal area may have contiguous bone damage. This bone involvement does not seem to be associated with neurological extension.

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

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

Prostate Infiltration by Treg and Th17 Cells as an Immune Response to Propionibacterium acnes Infection in the Course of Benign Prostatic Hyperplasia and Prostate Cancer

Benign prostatic hyperplasia (BPH) and prostate cancer (PCa) belong to the most frequent diseases in ageing men. It has been proposed that prostate chronic inflammation is a risk factor for the development of both BPH and PCa. However, potential stimuli that cause or maintain inflammation in the prostate gland are still poorly characterized. Bacterial infections seems to be one of the potential sources of prostatitis. Recent studies show that Propionibacterium acnes (P. acnes) is the most prevalent microorganism in the prostate gland and may be a predisposing factor for inflammation of prostatic tissue. It indicates that P. acnes may contribute to cancer development by enhancing proinflammatory responses, as well as by modifying the prostate extracellular environment. In this review, we discuss the potential role of P. acnes in the development of BPH and PCa and highlight the importance of regulatory T CD4(+)FoxP3(+) (Treg) and Th17 cells in response to P. acnes infection in the context of both prostate diseases.

Prevalence of Positive QuantiFERON-TB Test among Sarcoid Uveitis Patients and its Clinical Implications in a Country Non-endemic for Tuberculosis

AIM

To report on the prevalence and clinical implications of positive QuantiFERON-TB (QFT) test results in the diagnostic evaluation of a cohort of consecutive sarcoid uveitis patients in France.

DESIGN

Retrospective cross-sectional study.

METHODS

This study included consecutive sarcoid uveitis patients who all underwent QFT testing.

RESULTS

A total of 234 patients were included in the study, among them 28 (12%) were QFT-positive. Previously treated tuberculosis (TB) was documented in 2 patients. QFT-positive patients were older (59 ± 16 years vs. 51 ± 18 years, p = .025) and more in proportion to suffer from chronic uveitis and panuveitis compared to QFT-negative patients. Moderate and severe visual impairment were significantly more frequent in the QFT-positive group (35.7% vs. 18.9%, p = .049 and 25.0% vs. 9.2%, p = .022, respectively).

CONCLUSION

The significant proportion of QFT-positive patients (12%) in this large series of sarcoid uveitis patients makes us suggest not to exclude the diagnosis of sarcoidosis in case of positive QFT in a low-endemic country for tuberculosis, and to manage these patients early by initiating without delay systemic steroids associated with latent tuberculosis therapy.

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

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

Potential therapeutic targets to prevent organ damage in chronic pulmonary sarcoidosis

INTRODUCTION

Sarcoidosis is a granulomatous inflammatory disease with high chances of reduced quality of life, irreversible organ damage, and reduced life expectancy when vital organs are involved. Any organ system can be affected, and the lungs are most often affected. There is no preventive strategy as the exact etiology is unknown, and complex immunogenetic and environmental factors determine disease susceptibility and phenotype. Present-day treatment options originated from clinical practice and are effective in many patients. However, a substantial percentage of patients suffer from unacceptable side effects or still develop refractory, threatening pulmonary or extrapulmonary disease.

AREAS COVERED

As non-caseating granulomas, the pathological hallmark of disease, are assigned to divergent activation and regulation of the immune system, targets in relation to the possible triggers of granuloma formation and their sequelae were searched and reviewed.

EXPERT OPINION

:The immunopathogenesis underlying sarcoidosis has been a dynamic field of study. Several recent new insights give way to promising new therapeutic targets, such as certain antigenic triggers (e.g. from Aspergillus nidulans), mTOR, JAK-STAT and PPARγ pathways, the NRP2 receptor and MMP-12, which await further exploration. Clinical and trigger related phenotyping, and molecular endotyping in sarcoidosis will likely hold the key for precision medicine in the future.

Activation of Downstream mTORC1 Target Ribosomal Protein S6 Kinase (S6K) Can Be Found in a Subgroup of Dutch Patients with Granulomatous Pulmonary Disease

Mechanistic target of rapamycin complex 1 (mTORC1) has been linked to different diseases. The mTORC1 signaling pathway is suggested to play a role in the granuloma formation of sarcoidosis. Recent studies demonstrated conflicting data on mTORC1 activation in patients with sarcoidosis by measuring activation of its downstream target S6 kinase (S6K) with either 33% or 100% of patients. Therefore, the aim of our study was to reevaluate the percentage of S6K activation in sarcoidosis patients in a Dutch cohort. To investigate whether this activation is specific for sarcoid granulomas, we also included Dutch patients with other granulomatous diseases of the lung. The activation of the S6K signaling pathway was evaluated by immunohistochemical staining of its downstream effector phospho-S6 in tissue sections. Active S6K signaling was detected in 32 (43%) of the sarcoidosis patients. Twelve (31%) of the patients with another granulomatous disorder also showed activated S6K signaling, demonstrating that the mTORC1 pathway may be activated in a range for different granulomatous diseases (p = 0.628). Activation of S6K can only be found in a subgroup of patients with sarcoidosis, as well as in patients with other granulomatous pulmonary diseases, such as hypersensitivity pneumonitis or vasculitis. No association between different clinical phenotypes and S6K activation can be found in sarcoidosis.

Associations between occupational and environmental exposures and organ involvement in sarcoidosis: a retrospective case-case analysis

Background

Sarcoidosis most commonly affects lungs and intrathoracic lymph nodes, but any other organ can be involved. In epidemiological studies, many occupational and environmental exposures have been linked to sarcoidosis but their relationship with the disease phenotype has barely been studied.

Objective

To investigate how occupational and environmental exposures prior to diagnosis relate to organ involvement in patients with sarcoidosis

Methods

We retrospectively studied patients seen at a sarcoidosis clinic between 2017 and 2020. Patients were included if they had a clinical presentation consistent with sarcoidosis and histologically confirmed epithelioid granulomas or had Löfgren syndrome. In a case–case analysis using multivariable logistic regression we calculated odds ratios (OR) of prespecified exposure categories (based on expert ascertainment) for cases with a given organ involvement versus cases without this organ involvement.

Results

We included 238 sarcoidosis patients. Sarcoidosis limited to pulmonary involvement was associated with exposure to inorganic dust prior to diagnosis (OR 2.11; 95% confidence interval [CI] 1.11–4.17). Patients with liver involvement had higher odds of contact with livestock (OR 3.68; 95% CI 0.91–12.7) or having jobs with close human contact (OR 4.33; 95% CI 1.57–11.3) than patients without liver involvement. Similar associations were found for splenic involvement (livestock: OR 4.94, 95% CI 1.46–16.1; close human contact: OR 3.78; 95% CI 1.47–9.46). Cardiac sarcoidosis was associated with exposure to reactive chemicals (OR 5.08; 95% CI 1.28–19.2) or livestock (OR 9.86; 95% CI 1.95–49.0). Active smokers had more ocular sarcoidosis (OR 3.26; 95% CI 1.33–7.79).

Conclusions

Our study indicates that, in sarcoidosis patients, different exposures might be related to different organ involvements—hereby providing support for the hypothesis that sarcoidosis has more than one cause, each of which may promote a different disease phenotype.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12931-021-01818-5.

Immunohistochemical Detection of Propionibacterium acnes in Granulomas for Differentiating Sarcoidosis from Other Granulomatous Diseases Utilizing an Automated System with a Commercially Available PAB Antibody

Propionibacterium acnes is implicated in the pathogenesis of sarcoidosis. We investigated the usefulness of immunohistochemistry (IHC) with a commercially available P. acnes-specific monoclonal antibody (PAB antibody) for differentiating sarcoidosis from other granulomatous diseases. Formalin-fixed paraffin-embedded tissue samples from 94 sarcoidosis patients and 30 control patients with other granulomatous diseases were examined by the original manual IHC method. We also compared the detection frequency of P. acnes in sarcoid granulomas between manual and automated IHC methods. P. acnes was detected in sarcoid granulomas of samples obtained by transbronchial lung biopsy (64%), video-associated thoracic surgery (67%), endobronchial-ultrasound-guided transbronchial-needle aspiration (32%), lymph node biopsy (80%), and skin biopsy (80%) from sarcoidosis patients, but not in any non-sarcoid granulomas of the samples obtained from control patients. P. acnes outside granulomas, however, was frequently detected in both groups. The detection status of P. acnes in granulomas did not correlate with the clinical characteristics of sarcoidosis patients. The automated Leica system exhibited the best detection sensitivity (72%) and almost an identical localization for P. acnes in sarcoid granulomas compared with the manual method. IHC with a PAB antibody is useful for differentiating sarcoidosis from other granulomatous diseases by detecting P. acnes in granulomas. An automated method by the Leica system can be used in pathology laboratories for differential diagnosis of granulomas by IHC with the PAB antibody.

Sarcoidosis and autoimmunity

PURPOSE OF REVIEW

Sarcoidosis is a poorly understood multisystem granulomatous disease that frequently involves the lungs but can affect any organ system. In this review, we summarize recent developments in the understanding of the immune dysregulation seen in sarcoidosis and propose a new expanded definition of human autoimmunity in sarcoidosis, and the implications it would have on treating sarcoidosis with targeted immunotherapy regimens in the future.

RECENT FINDINGS

Sarcoidosis has been linked to infectious organisms like Mycobacterium and Cutibacterium, and certain manifestations of sarcoidosis have been linked to specific HLA alleles, but the overall pathogenesis remains uncertain. Sarcoidosis patients have similar patterns of cellular immune dysregulation seen in other autoimmune diseases like rheumatoid arthritis, and recent large-scale population studies show that sarcoidosis frequently presents with other autoimmune diseases.

SUMMARY

Advancements in the understanding of sarcoidosis support its consideration as an autoimmune disease. Sarcoidosis patients carry a higher risk of comorbid autoimmune conditions which offers an excellent opportunity to further understand autoimmunity and explore biologic therapies in sarcoidosis treatment, and furthermore will better targeted immunotherapy regimens for sarcoidosis patients in the future.

A Janus-Faced Bacterium: Host-Beneficial and -Detrimental Roles of Cutibacterium acnes

The bacterial species Cutibacterium acnes (formerly known as Propionibacterium acnes) is tightly associated with humans. It is the dominant bacterium in sebaceous regions of the human skin, where it preferentially colonizes the pilosebaceous unit. Multiple strains of C. acnes that belong to phylogenetically distinct types can co-exist. In this review we summarize and discuss the current knowledge of C. acnes regarding bacterial properties and traits that allow host colonization and play major roles in host-bacterium interactions and also regarding the host responses that C. acnes can trigger. These responses can have beneficial or detrimental consequences for the host. In the first part of the review, we highlight and critically review disease associations of C. acnes, in particular acne vulgaris, implant-associated infections and native infections. Here, we also analyse the current evidence for a direct or indirect role of a C. acnes-related dysbiosis in disease development or progression, i.e., reduced C. acnes strain diversity and/or the predominance of a certain phylotype. In the second part of the review, we highlight historical and recent findings demonstrating beneficial aspects of colonization by C. acnes such as colonization resistance, immune system interactions, and oxidant protection, and discuss the molecular mechanisms behind these effects. This new insight led to efforts in skin microbiota manipulation, such as the use of C. acnes strains as probiotic options to treat skin disorders.

Detection of Cutibacterium acnes in granulomas of patients with either hypersensitivity pneumonitis or vasculitis reveals that its presence is not unique for sarcoidosis

Granulomas are compact organised structures of different immune cells, including macrophages, lymphocytes and plasma cells, thought to be formed when (foreign) antigens cannot be cleared. The differential diagnosis of a granulomatous lesion is broad and includes infectious aetiologies, malignancy and inflammatory disorders like vasculitis, hypersensitivity pneumonitis and sarcoidosis [1].

Presence of C. acnes in granulomas is not unique to sarcoidosis but can also be found in patients with HP or EGPA. C. acnes may be involved in the pathogenesis of those granulomatous diseases in a mitogenic way.https://bit.ly/3pU0PeC

Elevated Serum Amyloid a Levels Are not Specific for Sarcoidosis but Associate with a Fibrotic Pulmonary Phenotype

Elevated Serum Amyloid A (SAA) levels have been found in several inflammatory diseases, including sarcoidosis. SAA is suggested to be involved in sarcoidosis pathogenesis by involvement in granuloma formation and maintenance. We hypothesized that SAA serum levels would be higher in sarcoidosis compared to other non-infectious granulomatous and non-granulomatous diseases. SAA levels were measured in serum from sarcoidosis, Hypersensitivity pneumonitis (HP), and (eosinophilic) granulomatosis with polyangiitis ((E)GPA) patients. Idiopathic pulmonary fibrosis (IPF) patients were included as non-granulomatous disease group. SAA levels of patients with sarcoidosis (31.0 µg/mL), HP (23.4 µg/mL), (E)GPA (36.9 µg/mL), and IPF (22.1 µg/mL) were all higher than SAA levels of healthy controls (10.1 µg/mL). SAA levels did not differ between the diagnostic groups. When SAA serum levels were analyzed in sarcoidosis subgroups, fibrotic sarcoidosis patients showed higher SAA levels than sarcoidosis patients without fibrosis (47.8 µg/mL vs. 29.4 µg/mL, p = 0.005). To conclude, the observation that fibrotic sarcoidosis patients have higher SAA levels, together with our finding that SAA levels were also increased in IPF patients, suggests that SAA may next to granulomatous processes also reflect the process of fibrogenesis. Further studies should clarify the exact role of SAA in fibrosis and the underlying mechanisms involved.