Th17-lineage cells in pulmonary sarcoidosis and Löfgren's syndrome: Friend or foe?

Circulating T cells in sarcoidosis have an aberrantly activated phenotype that correlates with disease outcome

RATIONALE

Disease course in sarcoidosis is highly variable. Bronchoalveolar lavage fluid and mediastinal lymph nodes show accumulation of activated T cells with a T-helper (Th)17.1 signature, which correlates with non-resolving sarcoidosis. We hypothesize that the peripheral blood (PB) T cell phenotype may correlate with outcome.

OBJECTIVES

To compare frequencies, phenotypes and function of circulating T cell populations in sarcoidosis patients with healthy controls (HCs) and correlate these parameters with outcome.

METHODS

We used multi-color flow cytometry to quantify activation marker expression on PB T cell subsets in treatment-naïve patients and HCs. The disease course was determined after 2-year follow-up. Cytokine production was measured after T cell stimulation in vitro.

MEASUREMENTS AND MAIN RESULTS

We observed significant differences between patients and HCs in several T cell populations, including CD8+ and CD4+ T cells, Th1/Th17 subsets, CD4+ T memory stem cells, regulatory T cells (Tregs) and γδ T cells. Decreased frequencies of CD4+ T cells and increased frequencies of Tregs and CD8+ γδ T cells correlated with worse outcome. Naïve CD4+ T cells displayed an activated phenotype with increased CD25 expression in patients with active chronic disease at 2-year follow-up. A distinctive Treg phenotype with increased expression of CD25, CTLA4, CD69, PD-1 and CD95 correlated with chronic sarcoidosis. Upon stimulation, both naïve and memory T cells displayed a different cytokine profile in sarcoidosis compared to HCs.

CONCLUSIONS

Circulating T cell subpopulations of sarcoidosis patients display phenotypic abnormalities that correlate with disease outcome, supporting a critical role of aberrant T cell activation in sarcoidosis pathogenesis.

The immunopathogenesis of sarcoidosis

Sarcoidosis is a granulomatous multiorgan disease, thought to result from exposure to yet unidentified antigens in genetically susceptible individuals. The exaggerated inflammatory response that leads to granuloma formation is highly complex and involves the innate and adaptive immune system. Consecutive immunological studies using advanced technology have increased our understanding of aberrantly activated immune cells, mediators and pathways that influence the formation, maintenance and resolution of granulomas. Over the years, it has become increasingly clear that disease immunopathogenesis can only be understood if the clinical heterogeneity of sarcoidosis is taken into consideration, along with the distribution of immune cells in peripheral blood and involved organs. Most studies offer an immunological snapshot during disease course, while the cellular composition of both the circulation and tissue microenvironment may change over time. Despite these challenges, novel insights on the role of the immune system are continuously published, thus bringing the field forward. This review highlights current knowledge on the innate and adaptive immune responses involved in sarcoidosis pathogenesis, as well as the pathways involved in non-resolving disease and fibrosis development. Additionally, we describe proposed immunological mechanisms responsible for drug-induced sarcoid like reactions. Although many aspects of disease immunopathogenesis remain to be unraveled, the identification of crucial immune reactions in sarcoidosis may help identify new treatment targets. We therefore also discuss potential therapies and future strategies based on the latest immunological findings.

Increased proportions of circulating PD-1+ CD4+ memory T cells and PD-1+ regulatory T cells associate with good response to prednisone in pulmonary sarcoidosis

BACKGROUND

The treatment response to corticosteroids in patients with sarcoidosis is highly variable. CD4+ T cells are central in sarcoid pathogenesis and their phenotype in peripheral blood (PB) associates with disease course. We hypothesized that the phenotype of circulating T cells in patients with sarcoidosis may correlate with the response to prednisone treatment. Therefore, we aimed to correlate frequencies and phenotypes of circulating T cells at baseline with the pulmonary function response at 3 and 12 months during prednisone treatment in patients with pulmonary sarcoidosis.

METHODS

We used multi-color flow cytometry to quantify activation marker expression on PB T cell populations in 22 treatment-naïve patients and 21 healthy controls (HCs). Pulmonary function tests at baseline, 3 and 12 months were used to measure treatment effect.

RESULTS

Patients with sarcoidosis showed an absolute forced vital capacity (FVC) increase of 14.2% predicted (± 10.6, p < 0.0001) between baseline and 3 months. Good response to prednisone (defined as absolute FVC increase of ≥ 10% predicted) was observed in 12 patients. CD4+ memory T cells and regulatory T cells from patients with sarcoidosis displayed an aberrant phenotype at baseline, compared to HCs. Good responders at 3 months had significantly increased baseline proportions of PD-1+CD4+ memory T cells and PD-1+ regulatory T cells, compared to poor responders and HCs. Moreover, decreased fractions of CD25+ cells and increased fractions of PD-1+ cells within the CD4+ memory T cell population correlated with ≥ 10% FVC increase at 12 months. During treatment, the aberrantly activated phenotype of memory and regulatory T cells reversed.

CONCLUSIONS

Increased proportions of circulating PD-1+CD4+ memory T cells and PD-1+ regulatory T cells and decreased proportions of CD25+CD4+ memory T cells associate with good FVC response to prednisone in pulmonary sarcoidosis, representing promising new blood biomarkers for prednisone efficacy.

TRIAL REGISTRATION

NL44805.078.13.

Advance in pathogenesis of sarcoidosis: Triggers and progression

Sarcoidosis, a multisystemic immune disease, significantly impacts patients' quality of life. The complexity and diversity of its pathogenesis, coupled with limited comprehensive research, had hampered both diagnosis and treatment, resulting in an unsatisfactory prognosis for many patients. In recent years, the research had made surprising progress in the triggers of sarcoidosis (genetic inheritance, infection and environmental factors) and the abnormal regulations on immunity during the formation of granuloma. This review consolidated the latest findings on sarcoidosis research, providing a systematic exploration of advanced studies on triggers, immune-related regulatory mechanisms, and clinical applications. By synthesizing previous discoveries, we aimed to offer valuable insights for future research directions and the development of clinical diagnosis and treatment strategies.

Anti-inflammatory Therapy for Sarcoidosis

Over 50% of patients with sarcoidosis will require anti-inflammatory therapy at some point in their disease course. Indications for therapy are to improve health-related quality of life, prevent or arrest organ dysfunction (or organ failure) or avoid death. Recently published treatment guidelines recommended a stepwise approach to therapy however there are some patients for whom up front combination or more intense therapy maybe reasonable. The last decade has seen an explosion of studies and trials evaluating novel therapeutic agents and treatment strategies. Currently available anti-inflammatory therapies and several novel therapies are discussed here.

Immune mechanisms of granuloma formation in sarcoidosis and tuberculosis

Sarcoidosis is a complex immune-mediated disease characterized by clusters of immune cells called granulomas. Despite major steps in understanding the cause of this disease, many questions remain. In this Review, we perform a mechanistic interrogation of the immune activities that contribute to granuloma formation in sarcoidosis and compare these processes with its closest mimic, tuberculosis, highlighting shared and divergent immune activities. We examine how Mycobacterium tuberculosis is sensed by the immune system; how the granuloma is initiated, formed, and perpetuated in tuberculosis compared with sarcoidosis; and the role of major innate and adaptive immune cells in shaping these processes. Finally, we draw these findings together around several recent high-resolution studies of the granuloma in situ that utilized the latest advances in single-cell technology combined with spatial methods to analyze plausible disease mechanisms. We conclude with an overall view of granuloma formation in sarcoidosis.

Sarcoidosis-related autoimmune inflammation in COVID-19 convalescent patients

Currently, there are a large number of reports about the development of autoimmune conditions after COVID-19. Also, there have been cases of sarcoid-like granulomas in convalescents as a part of the post-COVID-19 syndrome. Since one of the etiological theories of sarcoidosis considers it to be an autoimmune disease, we decided to study changes in the adaptive humoral immune response in sarcoidosis and SARS-CoV-2 infection and to find out whether COVID-19 can provoke the development of sarcoidosis. This review discusses histological changes in lymphoid organs in sarcoidosis and COVID-19, changes in B cell subpopulations, T-follicular helper cells (Tfh), and T-follicular regulatory cells (Tfr), and analyzes various autoantibodies detected in these pathologies. Based on the data studied, we concluded that SARS-CoV-2 infection may cause the development of autoimmune pathologies, in particular contributing to the onset of sarcoidosis in convalescents.

Increased circulating interleukin-23 level in patients with sarcoidosis

BACKGROUND

Sarcoidosis is a Th1-mediated chronic inflammatory disease characterized by non-caseating granulomas. Its pathogenesis is not yet clear, but the possible role of various proinflammatory cytokines is being discussed.

AIM

This study aims to determine serum cytokine (IL-6, IL-12, IL-17, and IL-23) levels in patients with sarcoidosis, and to determine a possible correlation with clinical and laboratory findings of the disease.

MATERIAL AND METHOD

Forty-four biopsy-proven sarcoidosis patients followed up at a single centre and 41 healthy volunteers were included in the study. Demographic, clinical, laboratory, and radiological data of all patients were recorded. Serum samples from the patients and the control group were taken and IL-6, IL-12, IL-17, IL-23 were measured by ELISA method.

RESULTS

Of the 44 sarcoidosis patients, 13(29.5%) were male and 31(70.5%) were female. Average patient age was 47.4 years, mean disease duration was 3.2 years. Twenty-one (47.7%) patients had erythema nodosum, three (6.8%) had uveitis, 40(90.9%) had arthralgia, 23(52.3%) had ankle arthritis, 15(34.1%) had enthesitis. Laboratory evaluation showed increased serum ACE levels in 24(54.5%) patients, increased serum calcium levels in 11 (25%) patients, increased serum D3 levels in 5(11.4%) patients, increased ESR and CRP levels in 22(50%) and 23(52.3%) patients, respectively. Compared with the control group higher serum IL-23 levels were found in the patients with sarcoidosis (p=.01). Serum IL-23 was associated with ankle arthritis (p=.02). Serum IL-6, IL-12, and IL-17 levels were similar in the sarcoidosis patients and the control group (p=.128, p=.212, p=.521 respectively).

CONCLUSION

In our study, we found increased serum IL-23 in patients with sarcoidosis, while serum IL-6, IL-12, and IL-17 were detected as normal. Although our results are somewhat contradictory to other studies in the literature, the question should still be whether sarcoidosis is a Th1/Th17 disease. Multicentre studies are needed in this regard.

Hilar/mediastinal and cutaneous drug-induced sarcoidosis-like reaction associated with immune checkpoint inhibitors in metastatic colorectal cancer: a case report

Background

Immune checkpoint inhibitors (ICIs) are the standard treatment for metastatic colorectal cancer (mCRC) with high microsatellite instability (MSI-H). Among immune-related adverse events (irAEs), drug-induced sarcoidosis-like reactions (DISR) are often difficult to differentiate from cancer progression.

Main Body

This is a case of a woman in her mid-60s, with mCRC (RAS wild/BRAF mutant/MSI-H) and abdominal lymph node metastasis, treated with four courses of ipilimumab + nivolumab every 3 weeks, followed by nivolumab every 2 weeks as third-line treatment. After treatment, the original lymph node metastases shrank, but hilar/mediastinal lymph nodes appeared. Endoscopic ultrasound-guided fine-needle aspiration of these lymph nodes revealed multiple epithelioid granulomas without necrosis, indicating a sarcoidosis-like reaction. Fluorodeoxyglucose-positron emission tomography scan showed abnormal subcutaneous accumulation in bilateral forearms and bilateral knee joints. Biopsy of the cutaneous lesions was also performed, which revealed epithelioid granulomas. As the patient had no symptoms in other organs, no specific therapeutic intervention was administered. After the discontinuation of immunotherapy, the sarcoidosis-like reaction regressed without cancer relapse.

Conclusions

Clinicians should be aware of the possibility of DISR as an irAE during the ICI treatment of mCRC. In suspected cases of DISR following ICI therapy, it is important to differentiate between cancer progression and DISR through histological diagnosis for the subsequent strategy, as radiological and serological findings are not definitive.

Sex differences in the genetics of sarcoidosis across European and African ancestry populations

Background

Sex differences in the susceptibility of sarcoidosis are unknown. The study aims to identify sex-dependent genetic variations in two clinical sarcoidosis phenotypes: Löfgren's syndrome (LS) and non-Löfgren's syndrome (non-LS).

Methods

A meta-analysis of genome-wide association studies was conducted on Europeans and African Americans, totaling 10,103 individuals from three population-based cohorts, Sweden (n = 3,843), Germany (n = 3,342), and the United States (n = 2,918), followed by an SNP lookup in the UK Biobank (UKB, n = 387,945). A genome-wide association study based on Immunochip data consisting of 141,000 single nucleotide polymorphisms (SNPs) was conducted in the sex groups. The association test was based on logistic regression using the additive model in LS and non-LS sex groups independently. Additionally, gene-based analysis, gene expression, expression quantitative trait loci (eQTL) mapping, and pathway analysis were performed to discover functionally relevant mechanisms related to sarcoidosis and biological sex.

Results

We identified sex-dependent genetic variations in LS and non-LS sex groups. Genetic findings in LS sex groups were explicitly located in the extended Major Histocompatibility Complex (xMHC). In non-LS, genetic differences in the sex groups were primarily located in the MHC class II subregion and ANXA11. Gene-based analysis and eQTL enrichment revealed distinct sex-specific gene expression patterns in various tissues and immune cell types. In LS sex groups, a pathway map related to antigen presentation machinery by IFN-gamma. In non-LS, pathway maps related to immune response lectin-induced complement pathway in males and related to maturation and migration of dendritic cells in skin sensitization in females were identified.

Conclusion

Our findings provide new evidence for a sex bias underlying sarcoidosis genetic architecture, particularly in clinical phenotypes LS and non-LS. Biological sex likely plays a role in disease mechanisms in sarcoidosis.

Sarcoidosis and Autoimmune Inflammatory Syndrome Induced by Adjuvants

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

Single-cell ATAC-seq maps the comprehensive and dynamic chromatin accessibility landscape of CAR-T cell dysfunction

Chimeric antigen receptor T cells (CAR-T) therapy has achieved remarkable therapeutic success in treating a variety of hematopoietic malignancies. However, the high relapse rate and poor in vivo persistence, partially caused by CAR-T cell exhaustion, are still important barriers against CAR-T therapy. It remains largely elusive on the mechanisms of CAR-T exhaustion and how to attenuate exhaustion to achieve better therapeutic efficacy. In this study, we initially observed that CAR-T cells showed rapid differentiation and increased exhaustion after co-culture with tumor cells in vitro, and then performed single-cell ATAC-seq to depict the comprehensive and dynamic landscape of chromatin accessibility of CAR-T cells during tumor cell stimulation. Analyses of differential chromatin accessible regions and motif accessibility revealed that TFs were distinct in each cell type and reconstituted a coordinated regulatory network to drive CAR-T exhaustion. Furthermore, we performed scATAC-seq in patient-derived CAR-T cells and identified BATF and IRF4 as pivotal regulators in CAR-T cell exhaustion. Finally, knockdown of BATF or IRF4 enhanced the killing ability, inhibited exhaustion, and prolonged the persistence of CAR-T cells in vivo. Together, our study unraveled the epigenetic regulatory mechanisms of CAR-T exhaustion and provided new insights into CAR-T engineering to achieve better clinical treatment benefits.

Sarcoidosis: Updates on therapeutic drug trials and novel treatment approaches

Sarcoidosis is a systemic granulomatous inflammatory disease of unknown etiology. It affects the lungs in over 90% of patients yet extra-pulmonary and multi-organ involvement is common. Spontaneous remission of disease occurs commonly, nonetheless, over 50% of patients will require treatment and up to 30% of patients will develop a chronic progressive non-remitting disease with marked pulmonary fibrosis leading to significant morbidity and death. Guidelines outlining an immunosuppressive treatment approach to sarcoidosis were recently published, however, the strength of evidence behind many of the guideline recommended drugs is weak. None of the drugs currently used for the treatment of sarcoidosis have been rigorously studied and prescription of these drugs is often based on off-label” indications informed by experience with other diseases. Indeed, only two medications [prednisone and repository corticotropin (RCI) injection] currently used in the treatment of sarcoidosis are approved by the United States Food and Drug Administration. This situation results in significant reimbursement challenges especially for the more advanced (and often more effective) drugs that are favored for severe and refractory forms of disease causing an over-reliance on corticosteroids known to be associated with significant dose and duration dependent toxicities. This past decade has seen a renewed interest in developing new drugs and exploring novel therapeutic pathways for the treatment of sarcoidosis. Several of these trials are active randomized controlled trials (RCTs) designed to recruit relatively large numbers of patients with a goal to determine the safety, efficacy, and tolerability of these new molecules and therapeutic approaches. While it is an exciting time, it is also necessary to exercise caution. Resources including research dollars and most importantly, patient populations available for trials are limited and thus necessitate that several of the challenges facing drug trials and drug development in sarcoidosis are addressed. This will ensure that currently available resources are judiciously utilized. Our paper reviews the ongoing and anticipated drug trials in sarcoidosis and addresses the challenges facing these and future trials. We also review several recently completed trials and draw lessons that should be applied in future.

From IL-17 to IFN-γ in inflammatory skin disorders: Is transdifferentiation a potential treatment target?

The targeted inhibition of effector cytokines such as interleukin 17 (IL-17) in psoriasis and IL-13 in atopic dermatitis offers impressive efficacy with a favorable side effect profile. In contrast, the downregulation of interferon gamma (IFN-γ) in T helper (Th) 1-dominant skin disorders may lead to more adverse events, given the crucial role of IFN-γ in antiviral and antitumoral immunity. Modulating Th17 and Th2 cell differentiation is performed by blocking IL-23 and IL-4, respectively, whereas anti-IL-12 antibodies are only moderately effective in downregulating Th1 lymphocyte differentiation. Therefore, a targeted approach of IFN-γ-driven disorders remains challenging. Recent literature suggests that certain pathogenic Th17 cell subsets with Th1 characteristics, such as CD4+CD161+CCR6+CXCR3+IL-17+IFN-y+ (Th17.1) and CD4+CD161+CCR6+CXCR3+IL-17-IFN-y+ (exTh17), are important contributors in Th1-mediated autoimmunity. Differentiation to a Th17.1 or exTh17 profile results in the upregulation of IFN-y. Remarkably, these pathogenic Th17 cell subsets are resistant to glucocorticoid therapy and the dampening effect of regulatory T cells (Treg). The identification of Th17.1/exTh17 cells in auto-immune disorders may explain the frequent treatment failure of conventional immunosuppressants. In this review, we summarize the current evidence regarding the cellular plasticity of Th17 cells in inflammatory skin disorders. A deeper understanding of this phenomenon may lead to better insights into the pathogenesis of various skin diseases and the discovery of a potential new treatment target.

Serum amyloid A/anti-CCL20 induced the rebalance of Th17/regulatory T cells in SodA-induced sarcoidosis

Sarcoidosis is a multisystemic granulomatous inflammation associated with Th17/regulatory T cell (Treg) polarization. As a marker of inflammation, serum amyloid A (SAA) could upregulate the expression of chemokine ligand 20 (CCL20), which induces the migration of Treg cells and Th17 cells by binding and activating thechemokine C-C receptor (CCR) 6. Our goal was to determine whether SAA/anti-CCL20 induces Th17/Treg rebalance in pulmonary sarcoidosis. The deposition of SAA- and Th17/Treg-related proteins in SodA-induced granulomas was tested using immunohistochemistry. Mice with SodA-induced sarcoidosis were treated with SAA or SAA + anti-CCL20, and then Th1/Th2 and Th17/Treg cells were detected by fluorescence-activated cell sorting (FACS) analysis. The expression of SAA/CCL20 and IL-23/IL-17A was detected by enzyme-linked immunosorbent assay (ELISA) and multiplex. Key proteins in the TGF-β/Smad signaling pathway were tested by western blot. SAA mainly plays a pro-inflammatory role by promoting the expression of CCL20 and IL-17A in bronchoalveolar lavage fluid (BALF) and serum, exacerbating this elevation of CD4+/CD8+ T cells in both mediastinal lymph nodes (LNs) and BALF, as well as proliferating Th1 in LNs in SodA-induced pulmonary sarcoidosis. In addition, SAA could also promote the proliferation of Tregs in LNs. Intriguingly, blocking of CCL20 could partially reverse the expression of Th17-related cytokine, ameliorate Th1/Th2 and Treg/Th17 bias in mice with SodA-induced pulmonary sarcoidosis, and rescue the overactivation of the TGF-β/Smad2/Smad3 signaling pathway. Anti-CCL20 may have the potential for therapeutic translation, targeting on the immunopathogenesis of pulmonary sarcoidosis.

Innate and Adaptive Immunity in Noninfectious Granulomatous Lung Disease

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

A Comprehensive Review of Sarcoidosis Diagnosis and Monitoring for the Pulmonologist

Sarcoidosis is a systemic granulomatous disease with heterogenous clinical manifestations. Here we review the diagnosis of sarcoidosis and propose a clinically feasible diagnostic work-up and monitoring protocol. As sarcoidosis is a systemic disease, a multidisciplinary approach is recommended for best outcomes. However, since the lungs are frequently involved, the pulmonologist is often the referral physician for diagnosis and management. When sarcoidosis is suspected, diagnosis needs to be confirmed and organ involvement/impairment assessed. This process is also required to establish whether the patient is likely to benefit from treatment, as many cases of sarcoidosis are self-limited and remit spontaneously. Whether or not treatment is started, effective regular follow-up is necessary to monitor changes in the disease, including extension, progression, remissions, flare-ups, and complications.

Pulmonary and blood dendritic cells from sarcoidosis patients more potently induce IFNγ-producing Th1 cells compared with monocytes

Sarcoidosis is a systemic inflammatory disease mainly affecting the lungs. The hallmark of sarcoidosis are granulomas that are surrounded by activated T cells, likely targeting the disease-inducing antigen. IFNγ-producing Th1 and Th17.1 T cells are elevated in sarcoidosis and associate with disease progression. Monocytes and dendritic cells (DCs) are antigen-presenting cells (APCs) and required for T cell activation. Several subsets of monocytes and DCs with different functions were identified in sarcoidosis. However, to what extent different monocyte and DC subsets can support activation and skewing of T cells in sarcoidosis is still unclear. In this study, we performed a transcriptional and functional side-by-side comparison of sorted monocytes and DCs from matched blood and bronchoalveolar lavage (BAL) fluid of sarcoidosis patients. Transcriptomic analysis of all subsets showed upregulation of genes related to T cell activation and antigen presentation in DCs compared with monocytes. Allogeneic T cell proliferation was higher after coculture with monocytes and DCs from blood compared with BAL and DCs induced more T cell proliferation compared with monocytes. After coculture, proliferating T cells showed high expression of the transcription factor Tbet and IFNγ production. We also identified Tbet and RORγt coexpressing T cells that mainly produced IFNγ. Our data show that DCs rather than monocytes from sarcoidosis patients have the ability to activate and polarize T cells towards Th1 and Th17.1 cells. This study provides a useful in vitro tool to better understand the contribution of monocytes and DCs to T cell activation and immunopathology in sarcoidosis.

The role of exosomes from BALF in lung disease

Exosomes are released from a variety of immune cells and nonimmune cells, the phospholipid vesicle bilayer membrane structure actively secreted into tissues. Recently, exosomes were demonstrated to be effectively delivered proteins, cholesterol, lipids, and amounts of DNA, mRNA, and noncoding RNAs to a target cell or tissue from a host cell. These can be detected in blood, urine, exhaled breath condensates, bronchoalveolar lavage fluid (BALF), ascites, and cerebrospinal fluid. BALF is a clinical examination method for obtaining alveolar cells and biochemical components, reflecting changes in the lungs, so it is also called liquid biopsy. Exosomes from BALF become a new method for intercellular communication and well‐documented in various pulmonary diseases. In chronic obstructive pulmonary disease (COPD), BALF exosomes can predict the degree of COPD damage and serve as an effective monitoring indicator for airflow limitation and airway remodeling. It also mediates antigen presentation in the airways to the adaptive immune system as well as costimulatory effects. Furthermore, BALF exosomes from acute lung injury and infective diseases are closely related to various infections and lack of oxygen status. BALF exosomes play an important role in the diagnosis and prognosis of lung cancer. The effect of immunomodulatory role for BALF exosomes in adaptive and innate immune responses has been studied in sarcoidosis. The intercellular communication in the microenvironment of BALF exosomes in pulmonary fibrosis and lung remodeling have been studied. In this review, we summarize the novel findings of exosomes in BALF, executed function by protein, miRNA, DNA cytokine, and so on in several pulmonary diseases.

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.

Drug-induced sarcoidosis-like reactions

PURPOSE OF REVIEW

Sarcoidosis is a complex granulomatous disease of unknown cause. Several drug categories are able to induce a systemic granulomatous indistinguishable from sarcoidosis, known as drug-induced sarcoidosis-like reaction (DISR). This granulomatous inflammation can resolve if the medication is discontinued. In this review, we discuss recent literature on medication associated with DISR, possible pathophysiology, clinical features, and treatment.

RECENT FINDINGS

Recently, increasing reports on DISR have expanded the list of drugs associated with the systemic granulomatous eruption. Most reported drugs can be categorized as combination antiretroviral therapy, tumor necrosis factor-α antagonist, interferons, and immune checkpoint inhibitors, but reports on other drugs are also published. The proposed mechanism is enhancement of the aberrant immune response which results in systemic granuloma formation. It is currently not possible to know whether DISR represents a separate entity or is a triggered but 'true' sarcoidosis.As DISRs may cause minimal symptoms, treatment is not always necessary and the benefits of continuing the offending drug should be weighed against clinical symptoms and organ dysfunction. Treatment may involve immunosuppressive medication that is used for sarcoidosis treatment.

SUMMARY

In this article, we review recent insights in DISR: associated drug categories, clinical presentation, diagnosis, and treatment. Additionally, we discuss possible mechanisms of DISR which can add to our knowledge of sarcoidosis pathophysiology.

A review on applications of abatacept in systemic rheumatic diseases

Abatacept is a CTLA-4Ig fusion protein that selectively modulates the CD80/CD86:CD28 costimulatory pathway required for full T-cell activation. The FDA has approved it to be used to treat adult rheumatoid arthritis, juvenile idiopathic arthritis, and adult active psoriatic arthritis. Considering the vital pathogenic role of the CTLA-4 pathway in autoimmune diseases, abatacept could efficiently treat other systemic rheumatic diseases. Here we reviewed the published literature to profile the perspectives about the off-label uses of abatacept, especially in those refractory cases with inadequate responses to conventional therapies and biologic agents. Abatacept can be a promising therapeutic option and contribute to reducing hormone dependence and correlated adverse events.

Arrhythmias in Cardiac Sarcoidosis Bench to Bedside: A Case-Based Review

Cardiac sarcoidosis is a component of an often multiorgan granulomatous disease of still uncertain cause. It is being recognized with increasing frequency, mainly as the result of heightened awareness and new diagnostic tests, specifically cardiac magnetic resonance imaging and ¹⁸F-fluorodeoxyglucose positron emission tomography scans. The purpose of this case-based review is to highlight the potentially life-saving importance of making the early diagnosis of cardiac sarcoidosis using these new tools and to provide a framework for the optimal care of patients with this disease. We will review disease mechanisms as currently understood, associated arrhythmias including conduction abnormalities, and atrial and ventricular tachyarrhythmias, guideline-directed diagnostic criteria, screening of patients with extracardiac sarcoidosis, and the use of pacemakers and defibrillators in this setting. Treatment options, including those related to heart failure, and those which may help clarify disease mechanisms are included.

Sarcoidosis: Causes, Diagnosis, Clinical Features, and Treatments

Sarcoidosis is a multisystem granulomatous disease with nonspecific clinical manifestations that commonly affects the pulmonary system and other organs including the eyes, skin, liver, spleen, and lymph nodes. Sarcoidosis usually presents with persistent dry cough, eye and skin manifestations, weight loss, fatigue, night sweats, and erythema nodosum. Sarcoidosis is not influenced by sex or age, although it is more common in adults (< 50 years) of African-American or Scandinavians decent. Diagnosis can be difficult because of nonspecific symptoms and can only be verified following histopathological examination. Various factors, including infection, genetic predisposition, and environmental factors, are involved in the pathology of sarcoidosis. Exposures to insecticides, herbicides, bioaerosols, and agricultural employment are also associated with an increased risk for sarcoidosis. Due to its unknown etiology, early diagnosis and detection are difficult; however, the advent of advanced technologies, such as endobronchial ultrasound-guided biopsy, high-resolution computed tomography, magnetic resonance imaging, and 18F-fluorodeoxyglucose positron emission tomography has improved our ability to reliably diagnose this condition and accurately forecast its prognosis. This review discusses the causes and clinical features of sarcoidosis, and the improvements made in its prognosis, therapeutic management, and the recent discovery of potential biomarkers associated with the diagnostic assay used for sarcoidosis confirmation.

Imbalance in B cell and T Follicular Helper Cell Subsets in Pulmonary Sarcoidosis

Sarcoidosis is a systemic granulomatous disease that develops due to the Th1, Th17 and Treg lymphocytes disturbance. There is an assumption, that B cells and follicular T-helper (Tfh) cells may play an important role in this disorder, as well as in several other autoimmune diseases. The aim of this study was to determine CD19+ B cells subset distribution in the peripheral blood and to define disturbance in the circulating Tfh cells subsets in patients with sarcoidosis. The prospective comparative study was performed in 2016-2018, where peripheral blood B cell subsets and circulating Tfh cell subsets were analyzed in 37 patients with primarily diagnosed sarcoidosis and 35 healthy donors using multicolor flow cytometry. In the results of our study we found the altered distribution of peripheral B cell subsets with a predominance of "naïve" (IgD + CD27-) and activated B cell (Bm2 and Bm2') subsets and a decreased frequency of memory cell (IgD+ CD27+ and IgD- CD27+) in peripheral blood of sarcoidosis patients was demonstrated. Moreover, we found that in sarcoidosis patients there are increased levels of B cell subsets, which were previously shown to display regulatory capacities (CD24+++ CD38+++ and CD5 + CD27-). Next, a significantly higher proportion of CXCR5-expressing CD45RA - CCR7+ Th cells in patients with sarcoidosis in comparison to the healthy controls was revealed, that represents the expansion of this memory Th cell subset in the disease. This is the first study to demonstrate the association between the development of sarcoidosis and imbalance of circulating Tfh cells, especially CCR4- and CXCR3-expressing Tfh subsets. Finally, based on our data we can assume that B cells and Tfh2- and Tfh17-like cells - most effective cell type in supporting B-cell activity, particularly in antibody production - may be involved in the occurrence and development of sarcoidosis and in several other autoimmune conditions. Therefore, we can consider these results as a new evidence of the autoimmune mechanisms in the sarcoidosis development.

Vitamin D supplementation for the prevention or depletion of side effects of therapy with alemtuzumab in multiple sclerosis

PURPOSE OF REVIEW

Not only the multiple sclerosis specialist but also the general neurologist and primary care practitioner are increasingly aware of possible adverse events (AEs) by treatment with alemtuzumab (over 47% risk of secondary autoimmune-mediated diseases). Vitamin D supplementation's effect (VDS) to reduce these autoimmune AEs is poorly performed in routine practice. This article seeks to justify why this simple, inexpensive, patient-friendly therapy should be seriously discussed.

RECENT FINDINGS

Patients who have developed autoimmunity also show a high basal level of IL-21, a cytokine which increases the growth of auto-reactive T-cells. For side effects such as thyroid dysfunction, autoimmune thrombocytopenia, autoimmune hemolytic anemia, autoimmune hepatitis, diabetes mellitus type 1, and alopecia areata/alopecia totalis, VDS may have an impact on the immunological mechanism, in particular lowering levels of IL-17 and IL-21.

SUMMARY

The potential role of vitamin D in influencing autoimmune diseases is evident. If a life-threatening side-effect can be prevented by high-dose VDS, it is ethical to initiate this add-on therapy despite contradictory results in studies on the effectiveness of VDS.

Sarcoidosis

Sarcoidosis is an inflammatory disorder of unknown cause that is characterized by granuloma formation in affected organs, most often in the lungs. Patients frequently suffer from cough, shortness of breath, chest pain and pronounced fatigue and are at risk of developing lung fibrosis or irreversible damage to other organs. The disease develops in genetically predisposed individuals with exposure to an as-yet unknown antigen. Genetic factors affect not only the risk of developing sarcoidosis but also the disease course, which is highly variable and difficult to predict. The typical T cell accumulation, local T cell immune response and granuloma formation in the lungs indicate that the inflammatory response in sarcoidosis is induced by specific antigens, possibly including self-antigens, which is consistent with an autoimmune involvement. Diagnosis can be challenging for clinicians because of the potential for almost any organ to be affected. As the aetiology of sarcoidosis is unknown, no specific treatment and no pathognomic markers exist. Thus, improved biomarkers to determine disease activity and to identify patients at risk of developing fibrosis are needed. Corticosteroids still constitute the first-line treatment, but new treatment strategies, including those targeting quality-of-life issues, are being evaluated and should yield appropriate, personalized and more effective treatments.

Phosphoinositide 3-kinase/protein kinase B inhibition restores regulatory T cell's function in pulmonary sarcoidosis

Sarcoidosis is a systemic granulomatous disease associated with Th1/ regulatory T cells (Treg) paradigm. PI3K/Akt signaling, critical for maintaining Treg's homeostasis, is aberrantly activated in sarcoidosis patients. Here we tested the role of the PI3K inhibitors, LY294002 and BKM120, in immune modulation in experimental pulmonary sarcoidosis, concerning Th1/Th17/Treg immune profile detected by fluorescence-activated cell sorting analysis or quantitative polymerase chain reaction, as well as the effect on Treg's suppressive functions. Our investigation showed abnormal activation of PI3K/Akt signaling both in lung and Treg in pulmonary sarcoidosis, along with decreased frequency and damaged function of Treg. Blockage of PI3K suppressed this signaling in Treg, rebalanced Th1/Treg, inhibited the production of inflammatory cytokines, and enhanced Treg's function. These results demonstrate the key role of the PI3K/Akt signaling in regulating Th1/Th2 rebalances and indicates that PI3K/Akt signaling is critical for the optimal Treg responses in pulmonary sarcoidosis. Thus, PI3K inhibitors have potential for therapeutic translation, and can be candidate for add-on drugs to treat pulmonary sarcoidosis.

Acute sarcoidosis in a multiple sclerosis patient after alemtuzumab treatment

Background:

Understanding the long-term effect of alemtuzumab on the immune system of multiple sclerosis (MS) patients is crucial.

Objective:

To report a case of acute sarcoidosis (Löfgren’s syndrome) in a relapsing-remitting MS patient, 1.5 years after the second course of alemtuzumab treatment.

Case report:

Sarcoidosis was confirmed dermatohistologically, radiologically, and serologically. Analysis of the lymphocyte subpopulations showed a persistent effect of alemtuzumab treatment (CD4/CD8 ratio increased, absolute lymphocyte count of CD19-positive cells increased while CD3/4/8-positive cells were decreased).

Conclusion:

Our case highlights the profound effect of alemtuzumab on the immune system and its possible risk for autoimmune complications.