Genotyping in the MHC locus: potential for defining predictive markers in sarcoidosis

Biologics in Dermatology: Off-Label Indications

Skin and subcutaneous diseases affect millions of people worldwide, causing significant morbidity. Biologics are becoming increasingly useful for the treatment of many skin diseases, particularly as alternatives for patients who have failed to tolerate or respond to conventional systemic therapies. Biological therapies provide a targeted approach to treatment through interaction with specific components of the underlying immune and inflammatory disease processes. Advances in the understanding of disease pathophysiology for inflammatory skin diseases and in drug development have ushered in biologic therapies in dermatology. Biologic therapies are molecules that target specific proteins implicated in immune-mediated disease. This review article highlights the increasing evidence base for biologics in dermatology for off-label use.

The Major Histocompatibility Complex of Old World Camels-A Synopsis

This study brings new information on major histocompatibility complex (MHC) class III sub-region genes in Old World camels and integrates current knowledge of the MHC region into a comprehensive overview for Old World camels. Out of the MHC class III genes characterized, TNFA and the LY6 gene family showed high levels of conservation, characteristic for MHC class III loci in general. For comparison, an MHC class II gene TAP1, not coding for antigen presenting molecules but functionally related to MHC antigen presenting functions was studied. TAP1 had many SNPs, even higher than the MHC class I and II genes encoding antigen presenting molecules. Based on this knowledge and using new camel genomic resources, we constructed an improved genomic map of the entire MHC region of Old World camels. The MHC class III sub-region shows a standard organization similar to that of pig or cattle. The overall genomic structure of the camel MHC is more similar to pig MHC than to cattle MHC. This conclusion is supported by differences in the organization of the MHC class II sub-region, absence of functional DY genes, different organization of MIC genes in the MHC class I sub-region, and generally closer evolutionary relationships of camel and porcine MHC gene sequences analyzed so far.

[Genetic risk profile of sarcoidosis]

Sarcoidosis is a multifactorial and polygenic disorder. The current knowledge of its genetic basis will be presented and functional consequences of the genetic variants that influence the immunopathogenesis of this disorder will be depicted. In the near future it is expected that this knowledge will yield clinically applicable genetic risk profiles.

The role of tumor necrosis factor alpha G-308A polymorphisms in the course of pulmonary sarcoidosis

This study was designed to evaluate the relationship between the presence of tumor necrosis factor (TNF) polymorphisms, human leukocyte antigen (HLA)-DRB1*03 linkage and the prognosis of sarcoidosis. In a retrospective case-control study, TNF-alpha G-308A, TNF-alpha G-238A, lymphotoxin-alpha (LTA) and HLA-DRB1*03 were genotyped in 625 sarcoidosis patients. These patients were classified into 298 patients with persistent disease and 327 patients with non-persistent disease using chest X-ray (CXR) appearances and lung function parameters after at least 2 years of follow-up. The TNF-alpha-308A variant allele was observed in 25.5% of patients with persistent disease compared with 44.0% of patients with non-persistent disease. The corresponding odds ratio (OR) was 0.43 with a 95% confidence interval (CI) of 0.30-0.61. A strong linkage was found between TNF-alpha G-308A and HLA-DRB1*03 (OR = 0.03, 95% CI: 0.02-0.05). For TNF-alpha G-238A and LTA NcoI A252G, there were no statistically significant differences in the distribution of genotypes between the groups with and without persistent disease. The data indicate that presence of a TNF-alpha-308A variant allele and HLA-DRB1*03 were associated with a favorable prognosis. Because of the strong linkage between TNF-alpha G-308A and HLA-DRB1*03, genotyping of one simple and less expensive TNF-alpha single nucleotide polymorphism can be used to predict the prognosis of pulmonary sarcoidosis in clinical practice.

Genetic predisposition to respiratory diseases: infiltrative lung diseases

The availability of high-throughput genotyping and large collaborative clinical networks creating well-characterized patient populations with DNA repositories has facilitated genome-wide scans and candidate gene studies to identify susceptibility alleles for the development of interstitial lung disease. The association of pulmonary fibrosis with rare inherited disorders, and the variable susceptibility of inbred mouse strains to this disease indicate that pulmonary fibrosis is determined by genetic factors. Sarcoidosis represents a complex disease with racial and ethnic differences in disease prevalence, and evidence of familial clustering. Familial aggregation of sarcoidosis from 'A Case-Control Etiologic Study of Sarcoidosis' (ACCESS) reveals a familial odds ratio (OR) of sarcoidosis of 5.8 (95% CI 2.1-15.9) for sibs and 3.8 (95% CI 1.2-11.3) for parents. Several HLA class II alleles have been associated with either increased or decreased risk of sarcoidosis, and results vary depending on study populations of different ethnicity. Genome-wide screening has conclusively identified linkage to chromosome 5q11and the development of sarcoidosis, and HLA genes and BTNL2 are susceptibility genes located in this region. Familial aggregation of idiopathic interstitial pneumonia (IIP) has been established by several groups, and a large US-based study suggests autosomal dominant inheritance with reduced penetrance; furthermore, cigarette smoking was associated with affection status among siblings (OR = 3.6, 95% CI 1.3-9.8, p = 0.01). Families demonstrate more than one type of IIP, suggesting various subtypes of IIP may share a common pathogenesis. Genome-wide linkage scans in familial interstitial pneumonia demonstrate linkage to chromosomes 4, 5 and 11. Candidate gene studies indicate that surfactant protein C and telomerase are susceptibility genes for the development of pulmonary fibrosis. Future challenges include determining how multiple susceptibility alleles interact with each other and environmental factors resulting in disease risk and multiple phenotypes, and determining the mechanism of action and cellular pathways involving susceptibility alleles. Further insight into these areas may lead to new therapeutic interventions.

Tumor necrosis factor gene polymorphisms in Turkish patients with sarcoidosis

BACKGROUND

As reported recently, some gene polymorphisms are suspected to determine susceptibility to sarcoidosis and are held responsible for the extent and progression of the disease. Polymorphism at -857 locus of tumor necrosis factor (TNF)-alpha gene is considered to be a predisposition factor in sarcoidosis and held responsible for pathogenesis of the disease. We compared these polymorphisms in healthy Turkish control subjects and Turkish patients with sarcoidosis.

METHODS

We examined gene polymorphisms in 90 cases which were histopathologically diagnosed as sarcoidosis and 110 healthy subjects without any history of a chronic disease. TNF-alpha-857 gene polymorphisms were determined using a polymerase chain reaction (PCR)-based method after DNA isolation. Genotype distributions of the groups were evaluated by the Hardy-Weinberg equilibrium test.

RESULTS

Genotype distributions were in agreement with the Hardy-Weinberg equilibrium both in sarcoidosis patients and healthy subjects. TNF-alpha gene (C/T) polymorphism, at position -857, revealed no differences in genotype and allele frequency between patients and control subjects but more relapses and more frequently involvement of three or more organs were found in sarcoidosis patients who have this polymorphism (p<0.05, p<0.01 respectively).

CONCLUSION

T allele at -857 locus of TNF gene is a marker for more extensive disease in Turkish sarcoidosis patients.

Association of TNF polymorphisms with sarcoidosis, its prognosis and tumour necrosis factor (TNF)-alpha levels in Asian Indians

Tumour necrosis factor (TNF)-alpha, an important proinflammatory cytokine, has been implicated in the pathogenesis of sarcoidosis, a multi-systemic granulomatous disorder of unknown aetiology. Here, we report for the first time the association of TNF haplotypes and genotypes with sarcoidosis and its prognosis in the Indian population. Five potentially functional promoter polymorphisms in the TNFA gene and a LTA_NcoI polymorphism (+252 position) of the LTA gene were genotyped in a clinically well-defined cohort of North-Indian patients with sarcoidosis (n = 96) and their regional controls (n = 155). Serum TNF-alpha (sTNF-alpha) and serum angiotensin converting enzyme (SACE) levels were measured and correlated with genotypes and haplotypes. The TNFA_-1031 and TNFA_-863 polymorphisms were identified as markers for disease onset (FET P = 0.006 and 0.042 for TNFA_-1031 and TNFA_-863, respectively). Additionally, the allele A of LTA_NcoI polymorphism was shown to be prevalent in the 'no treatment' group (FET P = 0.005), while the G allele was associated with frequent relapses on drug withdrawal (P = 0.057). Furthermore, the TNFA-308G>A and the TNFA-238G>A polymorphisms were found to influence sTNF-alpha (P = 0.054 and 0.0005, respectively) and SACE levels (P = 0.0017 and 0.056, respectively). The haplotype frequencies were significantly different in the patients and the controls (P = 0.0067). The haplotype GTCCGG was identified as the major risk/susceptibility haplotype (P = 0.003) and was associated with increased SACE levels in the patient population. In conclusion, our study suggests an association of TNF polymorphisms with sarcoidosis.

Association of tumour necrosis factor-alpha, lymphotoxin-alpha and HLA-DRB1 gene polymorphisms with Löfgren's syndrome in Czech patients with sarcoidosis

Sarcoidosis is a granulomatous disorder showing a clear association with MHC (HLA) class I and class II genes. In order to investigate whether polymorphisms of nearby pro-inflammatory genes located within the MHC class III region may also contribute to susceptibility to sarcoidosis or to its clinical manifestation, tumour necrosis factor-alpha (TNF-alpha) and lymphotoxin-alpha (LT-alpha) genes were chosen for analysis in a case-control association study. In order to evaluate the findings on the TNF-alpha and LT-alpha genes in connection with the closely linked MHC class II region, 'classical' HLA-DRB1 locus was also investigated. Polymerase chain reaction-based methodologies were used in order to characterize two single-nucleotide polymorphisms (TNF-308*G/A and LTAlpha+252*A/G) and HLA-DRB1 allele groups in 114 Czech patients with pulmonary sarcoidosis and 425 healthy controls. LTA+252*G and HLA-DRB1*13 allele carriers were more frequent in patients, compared to those in controls. By contrast, HLA-DRB1*07 carriers were less frequent among sarcoidosis patients. The overrepresentation of TNF-308*A, LTAlpha+252*G and HLA-DRB1*03 allele carriers was found in a subgroup of sarcoidosis patients presenting with Lofgren's syndrome (LS) by comparison with the subgroup of patients without LS (NLS; phenotype frequency LS vs NLS: 68.8 vs 37.1% for TNF-308*A, 93.8 vs 66.3% for LTA+252*G and 68.8 vs 21.3% for DRB1*03). The data suggest that the LTAlpha and HLA-DRB1 genes themselves or a gene located nearby contributes to the susceptibility to sarcoidosis and that TNF-308*A, LTA+252*G and HLA-DRB1*03 alleles are associated (directly or via linkage with unknown causative locus) with LS as a specific manifestation of the disease.

Human Leukocyte Antigen Class I Alleles and the Disease Course in Sarcoidosis Patients

Several lines of evidence suggest a genetic predisposition to sarcoidosis, and strong associations have been shown with the major histocompatibility complex gene complex. In this study on Scandinavian sarcoidosis patients, we investigated any influence on the outcome of disease by human leukocyte antigen (HLA) class I alleles alone and in combination with selected class II alleles. HLA-B*07 independently increased the risk for persistent sarcoidosis (odds ratio [OR], 1.9; 95% confidence interval [CI], 1.0-3.7), as well as for resolving disease (OR, 2.7; CI, 1.1-6.2), suggesting an influence on factors common to both forms of sarcoidosis. The common allele combination A*03, B*07, DRB1*15 was most strongly associated with persistent disease (OR, 4.7; CI, 2.2-10.2) and was found in 25.3% of patients with persistent disease versus 7.1% of healthy control subjects. HLA-B*08 tended to increase separately the risk for resolving disease (OR, 2.4; CI, 0.7-8.0), as well as for persistent disease (OR, 2.2; CI, 0.8-6.1). Other HLA class I associations were mainly secondary to their linkages to DRB1*03 and DRB1*15, respectively. The influence of HLA class I alleles on sarcoidosis thus seems more pronounced than previously thought, and both HLA class I and class II should be relevant to evaluate in the clinical management of sarcoidosis patients.

Helicobacter pylori-Related Immunoglobulins in Sarcoidosis

Background/Purpose

The purpose of this study was to determine serum antibody titers against a common bacterial antigen, Helicobacter pylori (H. pylori), in subjects with sarcoidosis, comparing those titers to those present in a healthy population.

Subjects and Methods

With the approval of the Institutional Review Board of the University of Missouri-Kansas City, patients with sarcoidosis (pulmonary and extrapulmonary) who visited the Truman Medical Center-Hospital Hill pulmonary clinic were recruited to enter the study. A serum sample was frozen at -70°C for later testing ( n = 20). Specific information collected on subjects included corticosteroid use, use of histamine2 blockers and antacids, date of first diagnosis, and stage of sarcoidosis. Normal controls and demographically matched individuals who lacked pulmonary diseases, including sarcoidosis, were also recruited. Serum samples were processed as above. Antibody capture enzyme immunoassay was completed for H. pylori and urease antigens by serum dilution assay for each subject, from which titers for antigen-specific immunoglobulin (lg)G and IgA were calculated. Nonspecific serum IgE was also measured.

Results

An increased incidence of high-titer IgG antibody directed against H. pylori antigens was found in subjects with sarcoidosis compared with controls. The sarcoidosis and control groups were significantly different with respect to IgG and IgA against H. pylori, both at p = .001. IgG directed against urease was also significantly different between sarcoidosis and control patients ( p = .001), but IgA directed against urease was very low in all subjects and did not yield significant differences between groups.

Conclusions

Specific H. pylori and urease IgG antibodies exceeded those expected in the population studied. The data suggest that in pulmonary sarcoidosis, the relationship of H. pylori and its products to sarcoid granuloma formation warrants further investigation.

Progressive cutaneous sarcoidosis responding to anti-tumor necrosis factor-alpha therapy

We describe a patient with widespread and progressive cutaneous sarcoidosis who was successfully treated with anti-tumor necrosis factor-alpha monoclonal antibody, infliximab, suggesting that inhibition of tumor necrosis factor-alpha may be useful as targeted treatment in cutaneous sarcoidosis.