Association of six well-characterized polymorphisms in TNF-α and TNF-β genes with sarcoidosis: a meta-analysis

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.

[Analysis of an association of TNF -308G>A polymorphism with a risk for pulmonary sarcoidosis in the Russian population of the Republic of Karelia]

AIM

To analyze an association of TNF -308G>A polymorphism with a risk for pulmonary sarcoidosis (PS) in the Russian population of the Republic of Kareli.

SUBJECTS AND METHODS

84 patients with persistent PS and 96 donors without clinical manifestations of this disease (a control group) were examined. Polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) analysis was used to identify alleles and genotypes by the marker of TNF -308G>A polymorphism. The level of transcripts of the above gene in the peripheral blood leukocytes of healthy and sick people was determined by real-time PCR.

RESULTS

There were no significant differences in the distribution of allelic and genotypic frequencies by the marker of TNF -308G>A polymorphism between the control and PS patient groups. There was a significant increase in the number of TNF gene transcripts in the peripheral blood leukocytes of patients with PS compared to the controls. At the same time, there were no marked differences in mRNA expression levels in the above gene in the carriers of different genotypes by the marker of TNF -308G>A polymorphism in all the examined groups.

CONCLUSION

The marker of TNF -308G>A polymorphism is unassociated with the risk of PS in the Russian population of the Republic of Karelia. No differences in TNF mRNA levels in the carriers of different genotypes by the above marker may suggest that the found elevated level of transcripts in the above gene in patients with diagnosed with PS is due to the development of the body's inflammatory responses in this disease.

The association between osteopontin gene polymorphisms, osteopontin expression and sarcoidosis

Background

Sarcoidosis is a systemic inflammatory disease of unknown etiology. Osteopontin (SPP1, OPN) is an extra cellular matrix glycoprotein and cytokine with a known role in granuloma formation and in autoimmune and inflammatory diseases.

Objective

To determine whether plasma OPN levels are elevated in patients with sarcoidosis and compare the frequency of four single nucleotide polymorphism (SNPs) variants in the OPN gene in sarcoidosis patients compared to healthy controls.

Methods

Demographic and clinical information, radiological studies and pulmonary function tests were evaluated in 113 patients with sarcoidosis and in 79 healthy controls. Blood samples were analyzed for SNPs of the OPN gene and for plasma OPN and CRP levels. Association between clinical features of disease and OPN levels as well as SNP frequencies was determined.

Results

Plasma OPN levels were higher in sarcoidosis patients than in healthy subjects, (median: 217 vs 122ng/ml, p<0.001). Area under the curve for receiver operator curves (ROC) was 0.798 (0.686–0.909 95% CI.) No differences were observed between sarcoidosis patients and controls in the frequency of any of the SNPs evaluated. Presence of lung parenchymal involvement was associated with SNP distribution at rs1126772 (p = 0.02). We found no correlation between SNPs distribution and plasma OPN levels.

Conclusions

Osteopontin protein levels are elevated in sarcoidosis. We found no evidence for an association between SNPs on the osteopontin gene and plasma OPN levels or the presence of sarcoidosis, however, an association between genotype and several phenotypic clinical parameters of disease was observed.

Particulate matter granulomas masquerading as sarcoidosis: a diagnostic dilemma

Sarcoidosis is a multiorgan disease with no single etiology. Evidence over the years points to complex interactions between environmental and genetic factors and a hypersensitive immune response to these insults. This brief overview discusses the uncertainty in the diagnosis of sarcoidosis versus other granulomatous diseases masquerading as sarcoidosis. The diagnostic dilemma is highlighted by a brief case review. The development of newer techniques in molecular biology and the identification of a panel of biomarkers in the future with appreciable specificity and sensitivity would help in the process. Future studies to determine receiver operating curves (ROC) using multiple biomarker combinations would help develop robust testing. More in-depth studies are also needed for defining the immunological basis of sarcoidosis because recent studies implicate Th17 cells in addition to the Th1 cell pathway. It is very likely that direct exposure to environmental agents and systemic distribution of these agents can elicit an exaggerated immune response leading to multiorgan granuloma formation mimicking sarcoidosis. A genetically susceptible host may be necessary to complete the granulomatous response to the particulate matter.