Familial sarcoidosis in Finland and Hokkaido, Japan--a comparative study

National retrospective registry survey on the epidemiology of sarcoidosis in Finland 2002-2022

BACKGROUND

The prevalence of sarcoidosis is known to be high in the Nordic countries. There are no recent research data on the incidence or prevalence of sarcoidosis in Finland. Our aim was to investigate the epidemiology of sarcoidosis in Finland through a retrospective registry-based study.

METHODS

We made an information request to the Hilmo database on patients who had been treated in Finnish specialised care with a main diagnosis related to sarcoidosis. Data were requested for the period 1 January-31 December for the years 2002, 2012 and 2022. In addition, we examined the age and gender distribution and regional differences in these variables between the five university hospital districts covering the whole of Finland.

RESULTS

The incidence of sarcoidosis was 17‒19/100 000/year throughout the follow-up period. The prevalence of sarcoidosis in the ≥18-year-old population had risen from 85/100 000 in 2002-106/100 000 in 2022. There were considerable differences between university hospital districts: The highest prevalence rate was 170/100 000 in the Tampere University Hospital district in 2022, which was twice as high as in the Helsinki University Hospital district (84/100 000). The proportion of pulmonary sarcoidosis in all sarcoidosis cases decreased from 62% to 45% while the proportion of multiorgan sarcoidosis (D86.8) increased from 11% to 34%. The incidence of sarcoidosis was 15/100 000 and the prevalence was 82/100 000 in the age groups of ≥60 years in 2002. In 2022, the incidence in this same age group had risen to 20/100 000 and the prevalence to 109/100 000. In the ≥60-year-old population, the proportion of D86.8 increased from 11% to 35%.

CONCLUSIONS

Sarcoidosis was a more common disease in Finland than in previous studies. Multiorgan sarcoidosis among the elderly has increased over the past 20 years. This might be explained by changes in environmental factors associated with sarcoidosis. Significant regional differences in prevalence might be partly explained by familial clustering.

Infectious and non-infectious precipitants of sarcoidosis

Sarcoidosis is a chronic inflammatory disease that can affect any organ in the body. Its exact cause remains unknown, but it is believed to result from a combination of genetic and environmental factors. Some potential causes of sarcoidosis include genetics, environmental triggers, immune system dysfunction, the gut microbiome, sex, and race/ethnicity. Genetic mutations are associated with protection against disease progression or an increased susceptibility to more severe disease, while exposure to certain chemicals, bacteria, viruses, or allergens can trigger the formation of immune cell congregations (granulomas) in different organs. Dysfunction of the immune system, including autoimmune reactions, may also contribute. The gut microbiome and factors such as being female or having African American, Scandinavian, Irish, or Puerto Rican heritage are additional contributors to disease outcome. Recent research has suggested that certain drugs, such as anti-Programmed Death-1 (PD-1) and antibiotics such as tuberculosis (TB) drugs, may raise the risk of developing sarcoidosis. Hormone levels, particularly higher levels of estrogen and progesterone in women, have also been linked to an increased likelihood of sarcoidosis. The diagnosis of sarcoidosis involves a comprehensive assessment that includes medical history, physical examination, laboratory tests, and imaging studies. While there is no cure for sarcoidosis, the symptoms can often be effectively managed through various treatment options. Treatment may involve the use of medications, surgical interventions, or lifestyle changes. These disparate factors suggests that sarcoidosis has multiple positive and negative exacerbants on disease severity, some of which can be ameliorated and others which cannot.

Sarcoidosis in first- and second-generation immigrants: a cohort study of all adults 18 years of age and older in Sweden

BACKGROUND

There is a lack of studies on sarcoidosis among immigrants, which is of interest as there may be genetic and environmental characteristics affecting immigrants from certain countries. We aimed to study hazard ratios (HRs) of sarcoidosis in first- and second-generation immigrants, comparing them with native Swedes in the total adult Swedish population.

METHODS

We conducted a nationwide study of individuals ≥18 y of age. Sarcoidosis was defined as at least two registered diagnoses in the National Patient Register between 1 January 1998 and 31 December 2018. Cox regression analysis was used to estimate HRs with 99% confidence intervals (CIs) of first registration of sarcoidosis in first- and second-generation immigrants compared with native Swedes. The Cox regression models were stratified by sex and adjusted for age, comorbidities and sociodemographic characteristics.

RESULTS

In total, 6 175 251 were included in the first-generation study, with 12 617 cases of sarcoidosis, and 4 585 529 in the second-generation study, with 12 126 cases. The overall sarcoidosis risk was lower in foreign-born men (fully adjusted HR 0.63 [99% CI 0.57 to 0.69]) but not in foreign-born women (fully adjusted HR 0.98 [99% CI 0.90 to 1.06]). The overall risk was slightly lower in second-generation immigrants (HR 0.82 [99% CI 0.78 to 0.88]). Women from Asia exhibited a higher risk (HR 1.25 [99% CI 1.02 to 1.53)], while a potential trend was observed among women from Africa (HR 1.47 [99% CI 0.99 to 2.19]).

CONCLUSIONS

Sarcoidosis risk was lower in foreign-born men but not in women and also lower in second-generation immigrants.

Hematological involvement in sarcoidosis: from cytopenias to lymphoma

INTRODUCTION

We present an updated overview of the hematological involvementassociated with sarcoidosis, including a management approach forcytopenias and revisiting the association with hematologicalmalignancies.

AREAS COVERED

Theetiology of cytopenias in sarcoidosis can be attributed to two majoretiopathogenic mechanisms: infiltration of hematopoietic organs suchas the spleen and bone marrow, and autoimmune-mediated cytopenias.With respect to the association with hematological malignancies, itrequires careful evaluation of patients from a chronologicalperspective. Patients must be classified into one of three pathogenicscenarios, including preexisting hematological malignancies,synchronous development of malignancy and sarcoidosis due to commonpredisposing factors, or sarcoidosis as a predisposing factor formalignancies.

EXPERT OPINION

The association between sarcoidosis and hematologic involvement isbest understood as a pathogenic continuum, with cytopenias andhematologic neoplasms intertwined due to various etiopathogenicmechanisms. These mechanisms include sarcoid infiltration ofhematopoietic organs, common predisposing immunogenetics for thedevelopment of autoimmune cytopenias and malignancies, and anincreased risk of neoplasm development in patients with autoimmunecytopenias. Collaboration among the main specialties involved in theclinical management of these patients is crucial for an earlymonitoring and management.

Pulmonary sarcoidosis with and without extrapulmonary involvement: a cross-sectional and observational study in China

OBJECTIVES

Sarcoidosis is a multisystem disease characterised by the formation of granulomas within various organs, mainly the lungs. Several studies from different countries have been undertaken to investigate sarcoidosis with extrapulmonary involvement except from China. The objective of this study is to investigate a comparative clinical analysis in patients with pulmonary sarcoidosis with and without extrapulmonary involvement from China.

METHODS

Data from inpatients diagnosed with sarcoidosis at Shanghai Pulmonary Hospital (Shanghai, China) between January 2009 and December 2014 were retrospectively collected and analysed. Six hundred and thirty-six patients with biopsy-proven sarcoidosis were included in the study, including 378 isolated pulmonary sarcoidosis and 258 pulmonary sarcoidosis plus extrapulmonary involvement.

RESULTS

Two hundred and fifty-eight (40.6%) patients with pulmonary sarcoidosis had extrapulmonary involvement. Extrapulmonary localisations were detected mostly in extrathoracic lymph nodes (n=147) and skin (n=86). Statistically significant differences were demonstrated between patients with pulmonary sarcoidosis plus extrapulmonary involvement and patients with isolated pulmonary sarcoidosis for fatigue (16.6%vs8.3%, P<0.05), serum ACE (SACE) levels (79.0±46.9 IU/L vs 69.7±38.7 IU/L, P<0.05), and high-resolution CT (HRCT) findings (53.8%vs46.2%, P<0.05).

CONCLUSIONS

Extrapulmonary involvement is common in patients with pulmonary sarcoidosis, with the most common sites being extrathoracic lymph nodes and skin. Patients with sarcoidosis with extrapulmonary involvement are more symptomatic (fatigue), have higher SACE levels and more deteriorating HRCT findings, to which clinicians should pay attention.

Familial sarcoidosis: Report of a mother and her son

Sarcoidosis is a chronic, multisystemic inflammatory disease, characterized with noncaseating granulomas. The pathogenesis of the disease is not yet clear, however, the main hypothesis is impaired and inadequate immune response developing against different environmental triggers in genetically predisposed people. The role of genetic factors in the development of sarcoidosis is well known. Over many years, familial sarcoidosis cases have been reported in various studies. In this report, we present familial sarcoidosis cases in a mother and her son.

Clinical and Biological Insights from the University of California San Francisco Prospective and Longitudinal Cohort

INTRODUCTION

Sarcoidosis is a systemic inflammatory disease characterized by non-necrotizing granulomas in involved organs, most commonly the lung. Description of patient characteristics in the Western United States is limited. Furthermore, blood-based measures that relate to clinical sarcoidosis phenotypes are lacking. We present an analysis of a prospective, longitudinal sarcoidosis cohort at a Northern Californian academic medical center.

METHODS

We enrolled 126 sarcoidosis subjects and 64 healthy controls and recorded baseline demographic and clinical characteristics. We used regression models to identify factors independently associated with pulmonary physiology. We tested whether blood transcript levels at study entry could relate to longitudinal changes in pulmonary physiology.

RESULTS

White, non-Hispanics composed ~70% of subjects. Hispanics and Blacks had a diagnostic biopsy at an age ~7 years younger than whites. Obstructive, but not restrictive, physiology characterized Scadding Stage IV patients. Subjects reporting use of immunosuppression had worse FEV1%p, FVC%p, and DLCO%p compared to subjects never treated, regardless of Scadding stage. We defined sarcoidosis disease activity by a drop in pulmonary function over 36 months and found that subjects meeting this definition had significant repression of blood gene transcripts related to T cell receptor signaling pathways, referred to as the "TCR factor."

CONCLUSION

Obstructive pulmonary physiology defined Stage IV patients which were mostly white, non-Hispanics. Genes comprising the composite gene expression score, TCR factor, may represent a blood-derived measure of T-cell activity and an indirect measure of active sarcoidosis inflammation. Validation of this measure could translate into individualized treatment for sarcoidosis patients.

Animal models of sarcoidosis

Sarcoidosis is a debilitating, inflammatory, multiorgan, granulomatous disease of unknown cause, commonly affecting the lung. In contrast to other chronic lung diseases such as interstitial pulmonary fibrosis or pulmonary arterial hypertension, there is so far no widely accepted or implemented animal model for this disease. This has hampered our insights into the etiology of sarcoidosis, the mechanisms of its pathogenesis, the identification of new biomarkers and diagnostic tools and, last not least, the development and implementation of novel treatment strategies. Over past years, however, a number of new animal models have been described that may provide useful tools to fill these critical knowledge gaps. In this review, we therefore outline the present status quo for animal models of sarcoidosis, comparing their pros and cons with respect to their ability to mimic the etiological, clinical and histological hallmarks of human disease and discuss their applicability for future research. Overall, the recent surge in animal models has markedly expanded our options for translational research; however, given the relative early stage of most animal models for sarcoidosis, appropriate replication of etiological and histological features of clinical disease, reproducibility and usefulness in terms of identification of new therapeutic targets and biomarkers, and testing of new treatments should be prioritized when considering the refinement of existing or the development of new models.

Predictors of objective cough frequency in pulmonary sarcoidosis

Cough is a common symptom of pulmonary sarcoidosis. This study aimed to quantify cough frequency, and investigate its relationship with cough reflex sensitivity, pulmonary function and health status.32 patients with pulmonary sarcoidosis were compared with 40 healthy controls. Cough reflex sensitivity to capsaicin, objective 24-h cough counts, cough-specific health status, cough severity and cough triggers were measured. The predictors of cough frequency in sarcoidosis were determined in a multivariate analysis.Objective cough frequency was significantly raised in patients with sarcoidosis compared with healthy controls (p<0.001) and patients with cough had an impaired health status. Patients with pulmonary sarcoidosis had a heightened cough reflex sensitivity compared with healthy controls (p<0.001). Only cough reflex sensitivity was significantly associated with objective cough frequency in multivariate analysis, explaining 42% of the variance (p<0.001). There was no association between cough frequency, lung function, number of organs involved, chest radiograph stage or serum angiotensin-converting enzyme levels.Cough is a common and significant symptom in patients with sarcoidosis. Ambulatory objective cough monitoring provides novel insights into the determinants of cough in sarcoidosis, suggesting that cough reflex sensitivity may be more important than lung function and other measures of disease severity, and this should be investigated further.

Genetics of Sarcoidosis

Sarcoidosis is a disease with highly variable presentation and progression; although it is hypothesized that disease phenotype is related to genetic variation, how much of this variability is driven by genetic factors is not known. The HLA region is the most strongly and consistently associated genetic risk factor for sarcoidosis, supporting the notion that sarcoidosis is an exposure-mediated immunologic disease. Most of the genetic etiology of sarcoidosis remains unknown in terms of the specific variants that increase risk in various populations, their biologic functions, and how they interact with environmental exposures.

Genetic testing in diffuse parenchymal lung disease

Diffuse parenchymal lung diseases (DPLD) represent a diverse group of disorders affecting the distal lung parenchyma, specifically the tissue and spaces surrounding the alveoli, which may be filled with inflammatory cells, proliferating fibroblasts or established fibrosis, often leading to architectural distortion and impaired gas exchange. While the underlying pathogenetic mechanisms are known or inferred for some DPLD (such as sarcoidosis, silicosis, drug reactions and collagen vascular diseases), the pathogenesis of the majority of these entities - particularly those characterized by progressive fibrosis - is poorly understood.

Several lines of evidence indicate that the development of pulmonary fibrosis is genetically determined. They include: 1. familial clustering; 2. the occurrence of pulmonary fibrosis in the context of rare inherited disorders; 3. substantial variability in the development of pulmonary fibrosis amongst individuals exposed to organic or inorganic dusts; 4. difference in susceptibility to fibrogenic stimuli amongst inbred strains of mice.

This review focuses on idiopathic pulmonary fibrosis (IPF) and sarcoidosis, the two most common DPLD and the two entities for which there is stronger evidence of a genetic predisposition, although how aberrant genes interact with each other and with environmental factors, such as smoking in IPF and infectious agents in sarcoidosis, in determining disease susceptibility and clinical phenotypes is largely unknown. Finally, we discuss practical issues and implications for both patients and physicians of recent advances in the genetics of sarcoidosis and IPF.

HLA-DRB1 allele frequencies and C4 copy number variation in Finnish sarcoidosis patients and associations with disease prognosis

Sarcoidosis is a multiorgan immune-mediated disease of unknown etiology with varying clinical pictures. We studied 3 genes in the major histocompatibility complex region (HLA-DRB1 and complement C4A and C4B) in patients with resolved disease after a 2-year follow-up (n = 90) and in patients whose disease was still active at that time point (n = 98) and compared them with controls (n = 150). Our primary aim was to detect genetic differences between the patient groups. We observed that the susceptibility allele for sarcoidosis was HLA-DRB1*15:01 (p = 0.011; odds ratio [OR] = 1.67) and the protective allele was HLA-DRB1*01:01 (p = 0.001; OR = 0.43). HLA-DRB1*03:01 was associated with resolving disease when compared with the persistent group (p = 0.011; OR = 2.22). The probability of having resolving disease was even greater if the patient had HLA-DRB1*03:01 and did not have extrapulmonary lesions (p = 0.001; OR = 3.39). By evaluating amino acid variants of the HLA-DRB1 gene, we determined that specific amino acids in pockets 4, 7, and 9 were associated with the prognosis of sarcoidosis. Our results support the importance of HLA-DRB1 as a predisposing gene for sarcoidosis. Particularly, HLA-DRB1*03:01 and polymorphisms of DRB1 pocket residues were associated with a favorable prognosis. Thus, accurate categorization of disease phenotype and HLA-DRB1 sequencing offer a basis for disease course estimation of sarcoidosis.

Interferon-alpha Induced Sarcoidosis with Cutaneous Involvement along the Lines of Venous Drainage

Sarcoidosis is a systemic inflammatory disease of an unknown origin and it is characterized by the presence of noncaseating epitheloid cell granulomas in multiple organs. Herein we report on a case of cutaneous and pulmonary sarcoidosis that was associated with interferon alpha treatment for hepatitis C. A 39-year-old man, a former intravenous drug user, presented with several erythematous papules on both antecubital areas. The histopathologic finding of a skin biopsy showed noncaseating granuloma. The mediastinal and axillary lymph nodes were enlarged on chest X-ray and computed tomography. To the best of our knowledge, this is the first report of cutaneous and pulmonary sarcoidosis that was associated with interferon treatment in the Korean dermatologic literature.

Sarcoidosis: clinical presentation, diagnosis, and approach to treatment

Sarcoidosis is an idiopathic granulomatous disease. It usually affects the lung but may involve any organ. The diagnosis may be problematic because known causes of granulomatous inflammation must be excluded. Sarcoidosis may remit spontaneously or remain stable. Therefore, therapy is not mandated for the disease. This report reviews the clinical presentation, diagnostic approach, and treatment of sarcoidosis.

Genetics of sarcoidosis

The predisposition to sarcoidosis is genetically determined, and genetics appears also to account for the variability in clinical phenotype and behaviour. Many genetic loci have been investigated to date, mainly in case-control association studies. However, only a small number of human leukocyte antigen (HLA) alleles have been consistently associated with sarcoidosis susceptibility/phenotype. In this regard, the association between Löfgren's syndrome and the extended HLA-DRB1*0301/DQB1*0201 haplotype is probably the most extensively reproduced. Several, generally less convincing, associations have been also reported. Of these, the chemokine receptor and butyrophilin-like 2 (BTNL2) associations are most promising. However, two major limitations of genetic studies are that the understanding of the biological relevance of gene variations in the genome is still incomplete and that the reported associations need to be verified in populations of different ethnicities. Despite a number of intriguing hypotheses, what causes sarcoidosis remains obscure. Genetic studies and, importantly, functional analysis of candidate genes will provide insight into pathogenesis and disease risk. However, if, as many believe, sarcoidosis is a heterogeneous collection of disorders, a critical step will be to carefully refine the clinical phenotype, as genetic studies of complex diseases are more rewording if a very specific disease subset is addressed.

Mycobacterial antigens may be important in sarcoidosis pathogenesis

PURPOSE OF REVIEW

To describe the most recent epidemiologic, molecular and immunologic literature related to the role of infectious antigens in sarcoidosis pathogenesis, with a focus upon Mycobacterium and Proprionibacterium species.

RECENT FINDINGS

Recent studies of successful molecular analysis for and humoral immunity to mycobacterial antigens from sarcoidosis patients have renewed interest in a potential role of mycobacteria in sarcoidosis. One study provided molecular and immunologic evidence for mycobacteria among sarcoidosis subjects from the United States. These studies, while preliminary, provide the groundwork for more in-depth studies of the potential role of mycobacteria in sarcoidosis pathogenesis. Proprionibacteria have also been proposed as a cause of sarcoidosis; a study of the detection of Proprionibacterium species nucleic acids throughout the lung of sarcoidosis and control subjects, however, suggests that these organisms are less likely to be causal.

SUMMARY

While the studies to date do not fulfill Koch's postulates, they do add further support to the hypothesis that infectious antigens, particularly those from mycobacteria, may have a causal role in some sarcoidosis cases. In future studies that purport to show an association of microbial antigen(s) with sarcoidosis, investigation of genetic risk factors contributing to risk will be important, in order to explain why some patients are found to have an association with microbial antigens and others are not.

Epidemiology of sarcoidosis: new frontiers to explore

Epidemiologic studies have been playing frontier roles to explore determinants of sarcoidosis by observing affected persons with the related population. Since 1990, more than 100 epidemiologic papers have been added to the Medline and PubMed databases. Of them, just a few were dated after March 2001. This article is focused on the papers after that time, referring to a number of previous important epidemiologic studies. The review is arranged according to two major epidemiologic categories: (1) host-related findings such as age, sex, race, familial clustering, and lifestyle; and also (2) time- and space-related findings such as exposures, geographical variation, local clustering, climate and seasonal variation, migration, and time-space clustering (transmission).

Familial aggregation of sarcoidosis. A case-control etiologic study of sarcoidosis (ACCESS)

Despite reports of familial clustering of sarcoidosis, little empirical evidence exists that disease risk in family members of sarcoidosis cases is greater than that in the general population. To address this question, we estimated sarcoidosis familial relative risk using data on disease occurrence in 10,862 first- and 17,047 second-degree relatives of 706 age, sex, race, and geographically matched cases and controls who participated in the multicenter ACCESS (A Case-Control Etiology Study of Sarcoidosis) study from 1996 to 1999. Familial relative risk estimates were calculated using a logistic regression technique that accounted for the dependence between relatives. Sibs had the highest relative risk (odds ratio [OR] = 5.8; 95% confidence interval [CI] = 2.1-15.9), followed by avuncular relationships (OR = 5.7; 95% CI = 1.6-20.7), grandparents (OR = 5.2; 95% CI = 1.5-18.0), and then parents (OR = 3.8; 95% CI = 1.2-11.3). In a multivariate model fit to the parents and sibs data, the familial relative risk adjusted for age, sex, relative class, and shared environment was 4.7 (95% CI = 2.3-9.7). White cases had a markedly higher familial relative risk compared with African-American cases (18.0 versus 2.8; p = 0.098). In summary, a significant elevated risk of sarcoidosis was observed among first- and second-degree relatives of sarcoidosis cases compared with relatives of matched control subjects.

Familial risk ratio of sarcoidosis in African-American sibs and parents

While sarcoidosis is thought to aggregate in families, little is known about the risk to relatives of sarcoidosis patients. To estimate the familial risk ratio (lambda) of sarcoidosis in sibs and parents of cases, the authors studied 179 African-American families ascertained through an index sarcoidosis case diagnosed at Henry Ford Hospital in Detroit, Michigan. Among those relatives enrolled between 1997 and 1999, 12 of 327 (3.7%) sibs and 11 of 161 (6.8%) parents reported a history of sarcoidosis. The lambda in this sample of relatives, estimated by computing an age, sex, and race standardized incidence ratio, was 2.24 (95% confidence interval: 1.16, 3.92) for sibs and 2.82 (95% confidence interval: 1.41, 5.05) for parents. For sibs and parents combined, lambda was 2.49 (95% confidence interval: 1.58, 3.73). Results stratified by proband characteristics indicated that lambda was greater for relatives of younger (lambda = 2.93, 95% confidence interval: 1.52, 5.12) and male (lambda = 3.98, 95% confidence interval: 1.99, 7.12) probands. A higher lambda was also found for male family members and sibs born later in the birth order. A Monte Carlo method was also used to estimate lambda, with similar results obtained. Overall, these results indicate that, in African Americans, sibs and parents of sarcoidosis cases have about a 2.5-fold increased risk for sarcoidosis and that heterogeneity in disease risk may exist among family members.

Epidemiology of familial sarcoidosis in the UK

BACKGROUND

The last comprehensive epidemiological studies on familial sarcoidosis in the UK were more than 25 years ago, reporting another affected family member in 1.7% of index cases. A significant proportion of like-sex over unlike-sex pairs, an excess of mother-child over father-child associations, and a preponderance of monozygous over dizygous twins was noted. Another study reported ethnic heterogeneity in familial disease. This study was undertaken to identify the risk ratio (lambda(S)) for siblings of familial sarcoidosis in the UK, to determine if the previous epidemiological findings have persisted, and to reassess whether ethnic heterogeneity prevails in familial disease.

METHOD

Questionnaires were sent to 406 index patients.

RESULTS

Two hundred and sixty eight replies (66%) were received. Twenty four of the original 406 index patients (5.91%) were found to have at least one other relative (first, second or third degree) with biopsy proven sarcoidosis. A lambda(S) value of 36-73 was calculated indicating significant familial clustering of the disease. Ethnically the families comprised 62.5% Caucasian, 29.2% Afro-Caribbean, and 8.3% Asian. Mean age at diagnosis was 39.8 years for women and 40.9 years for men with a male to female ratio of 1:1.7. This differed for the Asian families in which all the affected members were male. Three sets of female twins (two monozygous and one dizygous) were included. There was an equal distribution of like-sex (primarily female) and unlike-sex families as well as mother-child and father-child pairs. Pulmonary involvement was predominant irrespective of ethnicity, as was the need for corticosteroid treatment.

CONCLUSIONS

These results support the theory that a shared determinant (either genetic or environmental) is operating in familial sarcoidosis and suggest that this determinant is similar for all ethnic groups.