Complement receptor 1 gene polymorphisms in sarcoidosis

The complement cascade in lung injury and disease

BACKGROUND

The complement system is an important arm of immune defense bringing innate and adaptive immunity. Although originally regarded as a major complementary defense mechanism against pathogens, continuously emerging evidence has uncovered a central role of this complex system in several diseases including lung pathologies.

MAIN BODY

Complement factors such as anaphylatoxins C3a and C5a, their receptors C3aR, C5aR and C5aR2 as well as complement inhibitory proteins CD55, CD46 and CD59 have been implicated in pathologies such as the acute respiratory distress syndrome, pneumonia, chronic obstructive pulmonary disease, asthma, interstitial lung diseases, and lung cancer. However, the exact mechanisms by which complement factors induce these diseases remain unclear. Several complement-targeting monoclonal antibodies are reported to treat lung diseases.

CONCLUSIONS

The complement system contributes to the progression of the acute and chronic lung diseases. Better understanding of the underlying mechanisms will provide groundwork to develop new strategy to target complement factors for treatment of lung diseases.

Study on Potential Differentially Expressed Genes in Idiopathic Pulmonary Fibrosis by Bioinformatics and Next-Generation Sequencing Data Analysis

Idiopathic pulmonary fibrosis (IPF) is a chronic progressive lung disease with reduced quality of life and earlier mortality, but its pathogenesis and key genes are still unclear. In this investigation, bioinformatics was used to deeply analyze the pathogenesis of IPF and related key genes, so as to investigate the potential molecular pathogenesis of IPF and provide guidance for clinical treatment. Next-generation sequencing dataset GSE213001 was obtained from Gene Expression Omnibus (GEO), and the differentially expressed genes (DEGs) were identified between IPF and normal control group. The DEGs between IPF and normal control group were screened with the DESeq2 package of R language. The Gene Ontology (GO) and REACTOME pathway enrichment analyses of the DEGs were performed. Using the g:Profiler, the function and pathway enrichment analyses of DEGs were performed. Then, a protein-protein interaction (PPI) network was constructed via the Integrated Interactions Database (IID) database. Cytoscape with Network Analyzer was used to identify the hub genes. miRNet and NetworkAnalyst databaseswereused to construct the targeted microRNAs (miRNAs), transcription factors (TFs), and small drug molecules. Finally, receiver operating characteristic (ROC) curve analysis was used to validate the hub genes. A total of 958 DEGs were screened out in this study, including 479 up regulated genes and 479 down regulated genes. Most of the DEGs were significantly enriched in response to stimulus, GPCR ligand binding, microtubule-based process, and defective GALNT3 causes HFTC. In combination with the results of the PPI network, miRNA-hub gene regulatory network and TF-hub gene regulatory network, hub genes including LRRK2, BMI1, EBP, MNDA, KBTBD7, KRT15, OTX1, TEKT4, SPAG8, and EFHC2 were selected. Cyclothiazide and rotigotinethe are predicted small drug molecules for IPF treatment. Our findings will contribute to identification of potential biomarkers and novel strategies for the treatment of IPF, and provide a novel strategy for clinical therapy.

Elucidation of the low-expressing erythroid CR1 phenotype by bioinformatic mining of the GATA1-driven blood-group regulome

Genetic determinants underlying most human blood groups are now clarified but variation in expression levels remains largely unexplored. By developing a bioinformatics pipeline analyzing GATA1/Chromatin immunoprecipitation followed by sequencing (ChIP-seq) datasets, we identify 193 potential regulatory sites in 33 blood-group genes. As proof-of-concept, we aimed to delineate the low-expressing complement receptor 1 (CR1) Helgeson phenotype on erythrocytes, which is correlated with several diseases and protects against severe malaria. We demonstrate that two candidate CR1 enhancer motifs in intron 4 bind GATA1 and drive transcription. Both are functionally abolished by naturally-occurring SNVs. Erythrocyte CR1-mRNA and CR1 levels correlate dose-dependently with genotype of one SNV (rs11117991) in two healthy donor cohorts. Haplotype analysis of rs11117991 with previously proposed markers for Helgeson shows high linkage disequilibrium in Europeans but explains the poor prediction reported for Africans. These data resolve the longstanding debate on the genetic basis of inherited low CR1 and form a systematic starting point to investigate the blood group regulome.

Genetic polymorphisms in complement receptor 1 gene and its association with HBV-related liver disease: A case-control study

BACKGROUND

Several investigators have reported that complement receptor 1 (CR1) likely play a role in the pathogenesis of tumors, autoimmune and inflammatory diseases. However, the association of genetic polymorphisms of CR1 with risk of hepatitis B virus (HBV)-related liver disease remains unexplored.

METHODS

In a case-control study of 399 HBV-related liver disease patients and 227 healthy controls, we genotyped two SNPs in CR1 (rs3811381 and rs2274567) and assessed their associations with risk of HBV-related liver disease.

RESULTS

No significant differences were observed in the frequency distribution of genotypes or alleles between CR1 rs3811381 and rs2274567 polymorphisms in patients and controls. However, stratification analysis indicated that these two CR1 polymorphisms may contribute to the risk of HBV- hepatocellular carcinoma (HCC) and chronic hepatitis B (CHB) in subgroups of males, alcohol drinkers and nonsmokers. Further, our results showed that the rs3811381 polymorphism may contribute to HBV-HCC risk in subgroups of older and younger subjects, while the G allele, AG and the combined AG + GG genotypes of rs2274567 may be risk factors for HBV-HCC in younger subjects. In addition, our results indicated that subjects who carried the rs3811381 G allele and the rs2274567 AG genotype were at decreased risk of HBV- liver cirrhosis (LC) in subgroups of females.

CONCLUSIONS

Our results support the hypothesis that the CR1 gene rs3811381 and rs2274567 polymorphisms may contribute to HBV-HCC and HBV-CHB risk, particularly in subgroups of males, alcohol drinkers, nonsmokers, while these two CR1 polymorphisms were found to associate with decreased risk of HBV-LC, particularly in females. Further validation of these results is warranted.

Association of serum TNF-α, IL-8 and free light chain with HLA-DR B alleles expression in pulmonary and extra-pulmonary sarcoidosis

Background

Sarcoidosis is a systemic disease of unknown etiology characterized histologically by the observation of non-caseating granulomas and several immunological abnormalities. Sarcoidosis is a multi-organ disorder which involves formation of granulomas in many tissues including the lungs (pulmonary) and others such as skin, bone, heart (extra pulmonary). Associations between human leukocyte antigens (HLA), the encoded cell surface receptor (HLA-DR) and sarcoidosis have been reported in several studies. Several HLA-DR alleles have been described as potential risk factors for sarcoidosis in distinct ethnic groups however evidence for a relationship between HLA-DR alleles and pulmonary and extra-pulmonary sarcoidosis (EPS) is still scarce. Although the etiology of the disease remains unclear, infectious and environmental factors have been postulated. Inflammatory cytokines and chemokines may play important roles in the pathogenesis of sarcoidosis and serum free light chain (FLC) numbers have been implicated in several immunologic disorders.

Purpose of the study

The aim of the present study was to investigate HLA associations with serum cytokines and FLC in Iranian patients with pulmonary (n = 86) and EPS (n = 46).

Results

We found that among the 16 HLA DRB alleles only *7 and *12 were different in sarcoidosis patients. The levels of TNF-α and IL-8 in pulmonary sarcoidosis patients were higher than in EPS (P < 0.05) whereas the levels of FLC subunits in EPS were higher than in pulmonary sarcoidosis.

Conclusion

This data may suggests a link between HLA-DRB *12 and sarcoidosis in Iranian population.

Microbial and human heat shock proteins as 'danger signals' in sarcoidosis

In the light of the Matzinger's model of immune response, human heat shock proteins (HSPs) as main 'danger signals' (tissue damage-associated molecular patterns-DAMPs) or/and microbial HSPs as pathogen-associated molecular patterns (PAMPs) recognized by pattern recognition receptors (PRR), may induce sarcoid granuloma by both infectious and non-infectious factors in genetically different predisposed host. Regarding infectious causes of sarcoid models, low-virulence strains of, e.g. mycobacteria and propionibacteria recognized through changed PRR and persisting in altered host phagocytes, generate increased release of both human and microbial HSPs with their molecular and functional homology. High chronic spread of human and microbial HSPs altering cytokines, co-stimulatory molecules, and Tregs expression, apoptosis, oxidative stress, induces the autoimmunity, considered in sarcoidosis. Regarding non-infectious causes of sarcoidosis, human HSPs may be released at high levels during chronic low-grade exposure to misfolding amyloid precursor protein in stressed cells, phagocyted metal fumes, pigments with/without aluminum in tattoos, and due to heat shock in firefighters. Therefore, human HSPs as DAMPs and/or microbial HSPs as PAMPs produced as a result of non-infectious and infectious factors may induce different models of sarcoidosis, depending on the genetic background of the host. The number/expression of PRRs/ligands may influence the occurrence of sarcoidosis in particular organs.

Sarcoidosis: Immunopathogenesis and Immunological Markers

Sarcoidosis is a multisystem granulomatous disorder invariably affecting the lungs. It is a disease with noteworthy variations in clinical manifestation and disease outcome and has been described as an “immune paradox” with peripheral anergy despite exaggerated inflammation at disease sites. Despite extensive research, sarcoidosis remains a disease with undetermined aetiology. Current evidence supports the notion that the immune response in sarcoidosis is driven by a putative antigen in a genetically susceptible individual. Unfortunately, there currently exists no reliable biomarker to delineate the disease severity and prognosis. As such, the diagnosis of sarcoidosis remains a vexing clinical challenge. In this review, we outline the immunological features of sarcoidosis, discuss the evidence for and against various candidate etiological agents (infective and noninfective), describe the exhaled breath condensate, a novel method of identifying immunological biomarkers, and suggest other possible immunological biomarkers to better characterise the immunopathogenesis of sarcoidosis.

Complement receptor 1 variants confer protection from severe malaria in Odisha, India

Background

In Plasmodium falciparum infection, complement receptor-1 (CR1) on erythrocyte’s surface and ABO blood group play important roles in formation of rosettes which are presumed to be contributory in the pathogenesis of severe malaria. Although several studies have attempted to determine the association of CR1 polymorphisms with severe malaria, observations remain inconsistent. Therefore, a case control study and meta-analysis was performed to address this issue.

Methods

Common CR1 polymorphisms (intron 27 and exon 22) and blood group were typed in 353 cases of severe malaria (SM) [97 cerebral malaria (CM), 129 multi-organ dysfunction (MOD), 127 non-cerebral severe malaria (NCSM)], 141 un-complicated malaria and 100 healthy controls from an endemic region of Odisha, India. Relevant publications for meta-analysis were searched from the database.

Results

The homozygous polymorphisms of CR1 intron 27 and exon 22 (TT and GG) and alleles (T and G) that are associated with low expression of CR1 on red blood cells, conferred significant protection against CM, MOD and malaria deaths. Combined analysis showed significant association of blood group B/intron 27-AA/exon 22-AA with susceptibility to SM (CM and MOD). Meta-analysis revealed that the CR1 exon 22 low expression polymorphism is significantly associated with protection against severe malaria.

Conclusions

The results of the present study demonstrate that common CR1 variants significantly protect against severe malaria in an endemic area.

Changed phagocytic activity and pattern of Fcγ and complement receptors on blood monocytes in sarcoidosis

We have recently revealed that mycobacterial heat shock proteins (Mtb-hsp), involved in forming of immune complexes (CIs), can induce immune response in sarcoidosis (SA). The complexemia may result from inappropriate phagocytosis and clearance of CIs by monocytes with following persistent antigenemia and granuloma formation. Because an aberrant expression of receptors for Fc fragment of immunoglobulin G (FcγR) and complement receptors (CR) on monocytes can be involved in this process, we have evaluated the expression of FcγRI (CD64), FcγRII (CD32), FcγRIII (CD16) and CR1 (CD35), CR3 (CD11b), CR4 (CD11c) receptors on blood CD14(+) monocytes and its phagocytic activity in 24 patients with SA and 20 healthy volunteers using flow cytometry. We found significantly increased expression of all examined FcγR and decreased expression of CD35 and CD11c on CD14(+) monocytes in SA patients vs controls. Significantly increased percentage of CD14(+)CD16(+)CD35(-), CD14(+)CD64(+)CD35(+), CD14(+)CD64(+)CD11b(+), CD14(+)CD64(+)CD11c(+) and decreased of CD14(+)CD32(-)CD35(+), CD14(+)CD32(-)CD11b(+), CD14(+)CD32(-)CD11c(+) monocytes' phenotypes was revealed in SA. The total number and percentage of phagocyting monocytes was significantly increased in SA as compared with controls. In conclusion, altered expression of FcγR and CR on CD14(+) monocytes and its increased phagocytic activity may be responsible for high antigen load, persistent antigenemia and immunocomplexemia in SA patients.

Sarcoidosis--scientific progress and clinical challenges

Sarcoidosis is an uncommon systemic inflammatory disorder characterized by noncaseating granulomatous inflammation that most commonly affects the lungs, intrathoracic lymph nodes, eyes and skin. One-third or more of patients with sarcoidosis have chronic, unremitting inflammation with progressive organ impairment. Findings of family and genetic studies indicate a genetic susceptibility to sarcoidosis, with genes in the MHC region having a dominant role. Immunologic hallmarks of the disease include highly polarized expression of cytokines produced by type 1 T helper cells and tumor necrosis factor (TNF) at sites of inflammation. Increasing evidence obtained within the past decade suggests the etiology of sarcoidosis predominantly involves microbial triggers, with the most convincing data implicating mycobacterial or propionibacterial organisms. Innate immune mechanisms, possibly involving misfolding and aggregation of serum amyloid A, might have a critical role in the pathobiology of sarcoidosis. Despite these advances, there are no clinically useful biomarkers that can assist the clinician in diagnosis, prognosis or assessment of treatment effects. Corticosteroids remain the cornerstone of therapy when organ function is threatened or progressively impaired. The role of immunosuppressive drugs and anti-TNF agents in the treatment of sarcoidosis remains uncertain, and there are no FDA-approved therapies. Meaningful progress in developing clinically useful tools and new therapies will depend on further advances in understanding the pathogenesis of sarcoidosis and its disease-specific pathways.

[Sarcoidosis and genetics]

Familial features of sarcoidosis and observations in monozygotic twins affected by the condition suggest the presence of a genetic predisposition. Various genetic associations have been described with genes coding for proteins involved in immune regulation in particular at the level of interaction between T-lymphocyte and antigen presenting cell. We review the various genetic targets described with techniques ranging from classic human lymphocyte antigen genotype to genome wide linkage scans. The 6p21 region has been highlighted, which includes relevant genes such as MHC class II, BTNL2 and TNFα. These studies show that the genetics of sarcoidosis are complex, that patient sub-groups exist, which may explain some of the heterogeneity in the results of genetic studies and that the interactions between genetic and environmental factors remains to be elucidated.

Complement receptor 1 gene polymorphism and cardiovascular disease in dialyzed end-stage renal disease patients

Inflammation plays an important role in cardiovascular disease (CVD). The complement system is a critical component of innate and acquired immunity. We investigated whether the polymorphisms in the complement receptor 1 (CR1) gene are associated with CVD in end-stage renal disease (ESRD) patients. The study groups of 1200 patients with ESRD, 360 patients with type 2 diabetes and 924 healthy individuals were genotyped. The GG genotype of the C5507G polymorphism was significantly more frequent in ESRD patients with CVD than in patients without CVD and controls (odds ratio [OR] = 3.44, 95% confidence interval [CI] = 2.23-5.3, and OR = 5.46, 95% CI = 3.72-8.0, respectively). The GG genotype was observed in 62% of patients with a history of myocardial infarction. The frequency of the G allele was also higher in patients with CVD (OR = 2.24, 95% CI = 1.93-2.61 vs controls, and OR = 1.97, 95% CI = 1.63-2.36 vs patients without CVD). In the multivariate logistic regression analysis the carrier status of G allele of C5507G polymorphism was an independent risk factor of CVD in ESRD patients (p < 0.001). In conclusion, our results suggest strong association between the CR1 gene polymorphism and CVD in ESRD patients.

Determinants of initiation and progression of idiopathic pulmonary fibrosis

IPF is a devastating disease with few therapeutic options. The precise aetiology of IPF remains elusive. However, our understanding of the pathologic processes involved in the initiation and progression of this disease is improving. Data on the mechanisms underlying IPF have been generated from epidemiologic investigations as well as cellular and molecular studies of human tissues. Although no perfect animal model of human IPF exists, pre-clinical animal studies have helped define pathways which are likely important in human disease. Epithelial injury, fibroblast activation and repetitive cycles of injury and abnormal repair are almost certainly key events. Factors which have been associated with initiation and/or progression of IPF include viral infections, abnormal cytokine, chemokine and growth factor production, oxidant stress, autoimmunity, inhalational of toxicants and gastro-oesophageal reflux disease. Furthermore, recent evidence identifies a role for a variety of genetic and epigenetic abnormalities ranging from mutations in surfactant protein C to abnormalities in telomere length and telomerase activity. The challenge remains to identify additional inciting agents and key dysregulated pathways that lead to disease progression so that we can develop targeted therapies to treat or prevent this serious disease.

Complement receptor 1 (A3650G RsaI and intron 27 HindIII) polymorphisms and risk of gallbladder cancer in north Indian population

Decreased expression due to genetic variations in complement receptor 1 (CR1) on erythrocytes might result in reduced clearance of immune complexes, conferring interindividual variation for gallbladder cancer (GBC) susceptibility. We studied role of CR1 (A(3650)G RsaI and Intron 27 HindIII) polymorphisms in gallstone disease and GBC in north Indian population. Study included 185 GBC patients, 185 gallstone patients and 200 controls. Genotyping was done by PCR-RFLP. Result showed GG genotype and G allele of CR1 A(3650)G RsaI were conferring significant risk for GBC [(P = 0.022; OR = 1.94; 95% CI = 1.1-3.4) and (P = 0.035; OR = 1.35; 95% CI = 1.0-3.8) respectively]. Also, comparison of GBC patients with gallstone patients showed increased risk for GBC in presence of GG genotype and G allele GBC (P = 0.048; OR = 1.74; 95% CI = 1.0-3.0) and (P = 0.027; OR = 1.39; 95% CI = 1.0-1.8) respectively. No association of CR1 A(3650)G RsaI polymorphism was observed when gallstone patients were compared with controls. CR1 Intron 27 HindIII polymorphism was not associated with GBC and gallstone susceptibility. Haplotype analysis showed increased risk of GBC in presence of G,L haplotype (P = 0.046; OR = 1.35: 95% CI = 1.0-1.8). Subgroup stratifications on basis of gender and gallstone status showed GG genotype of CR1 A(3650)G RsaI polymorphism imparted high risk for GBC in females (P = 0.043; OR = 1.99: 95% CI = 1.4-3.9). Also there was increased risk for GBC in presence as well as absence of gallstones (OR = 1.85 and 1.76 respectively), but it was not statistically significant. We conclude that CR1 A(3650)G RsaI polymorphism plays an important role in conferring genetic susceptibility to gallbladder cancer GBC in north Indian population.

The CR1 C5507G polymorphism is not involved in susceptibility to idiopathic pulmonary fibrosis in two European populations

Idiopathic pulmonary fibrosis (IPF), a severe lung disease with unknown aetiology, is thought to have an important genetic component. Single nucleotide polymorphism, C5507G, of the complement receptor 1 (CR1) gene, which affects the number of CR1 molecules on erythrocytes, has been associated with susceptibility to IPF in a single European population. To replicate this finding, 53 Czech IPF patients with 203 Czech healthy control subjects and 70 English IPF patients with 149 English controls were investigated. In both populations, there were no significant differences in distribution of CR1 C5507G variants between IPF patients and their appropriate control groups. In conclusion, the association of the CR1 C5507G polymorphism with susceptibility to IPF was not reproducible in Czech and English populations.

Genetics of sarcoidosis

PURPOSE OF REVIEW

Increased familial occurrences as well as different disease modes in different ethnic groups suggest a genetic influence in sarcoidosis. Also, genetic analyses have revealed a number of chromosomal regions and specific genes associated with sarcoidosis. This review brings up some recent discoveries on the genetic contribution to sarcoidosis.

RECENT FINDINGS

As a more detailed clinical classification of patients is performed, stronger genetic associations between distinct clinical phenotypes and specific gene variants have been revealed. The strong association between human leucocyte antigen DRB10301/DQB10201 and good prognosis in patients with Löfgren's syndrome is one such recent example. Linkage studies have revealed certain chromosomal regions of interest and furthermore pointed out specific genes of interest, for example, a variant of the butyrophilin-like 2 gene.

SUMMARY

Sarcoidosis is a complex disease which is influenced by a multitude of genes and environmental factors. The strongest genetic associations are found within the human leucocyte antigen region, in which several specific human leucocyte antigen alleles clearly associate with disease risk and phenotype, but additional genes in the same region may turn out to be important as well. Future studies on large, clinically well defined patient cohorts will help to elucidate the genetic impact on sarcoidosis.

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.

Complement receptor 1 single nucleotide polymorphisms in Czech and Dutch patients with sarcoidosis

A single nucleotide polymorphism (SNP) C5507G of the complement receptor 1 (CR1) gene has been associated with genetic susceptibility to sarcoidosis in an Italian population. In order to provide further data on the possible involvement of CR1 gene polymorphisms in sarcoidosis, CR1 SNPs C5507G and A3650G were investigated in Czech (n = 210) and Dutch (n = 116) patients with sarcoidosis with ethnically matched groups of healthy control subjects (Czech, n = 203; Dutch, n = 112). CR1 C5507G and A3650G SNPs were not associated with susceptibility to sarcoidosis or its clinical course. Further, CR1 messenger RNA expression in bronchoalveolar lavage cells investigated by quantitative reverse transcriptase-polymerase chain reaction did not differ between sarcoidosis patients and control subjects and was not associated with the presence of the CR1 5507*G allele.

Expression of Receptor for Advanced Glycation End Products in Sarcoid Granulomas

RATIONALE

The receptor for advanced glycation end products (RAGE) engages a number of ligands implicated in inflammatory processes. The RAGE coding gene maps to the 6p21.32 region, close to the genes DRB1 and BTNL2, which are associated with sarcoidosis.

OBJECTIVES

We investigated a possible implication of RAGE in sarcoid granulomas.

METHODS

RAGE and major ligands (N-epsilon-carboxy-methyl-lysine [CML], S100A12, and S100B) expression was investigated by immunostaining of 99 paraffin-embedded biopsies of sarcoid tissues, and expression patterns were determined. Among the three RAGE gene single-nucleotide polymorphisms investigated, -374 T/A was selected, characterized in terms of transcriptional effect (immunocytochemistry and real-time polymerase chain reaction), and its frequency was determined in DNA extracted from biopsies.

MEASUREMENTS AND RESULTS

RAGE, CML, S100A12, and S100B immunoreactivity was observed in all sarcoid granulomas, although at different intensities. The degree of RAGE expression significantly correlated with the degree of S100A12 expression. The -374 TT/AT genotypes, associated with higher RAGE transcriptional activity, were more frequent in the sarcoidosis biopsy group than in control subjects, and the association was confirmed in a second, independent series of 101 patients with sarcoidosis.

CONCLUSIONS

We showed the association of RAGE and its ligands with sarcoidosis and suggest that an intrinsic genetic factor could be in part involved in its expression. In Italian patients, the -374 T/A polymorphism seems to be significantly associated with this disease.

Genetics of sarcoidosis: candidate genes and genome scans

Human leukocyte antigen class II allele associations and T-cell receptor beta chain bias in sarcoidosis suggest a specific disease-triggering antigen exposure in a genetically susceptible host. The cause of sarcoidosis has been elusive, but genetics provides one of the few promising avenues to further our understanding. We review the association studies and genome scans used to identify the genes involved in sarcoidosis.

The merits of testing Hardy-Weinberg equilibrium in the analysis of unmatched case-control data: a cautionary note

Testing for departures from the assumption of Hardy-Weinberg equilibrium (HWE) has been widely recommended as a preliminary step in the analysis of genetic case-control studies. Some authors suggest using a two-stage procedure in which gene/disease associations are ultimately evaluated using either the Pearson chi-square procedure or the Cochran-Armitage test for trend. Other authors go further and encourage investigators to discard data that are in violation of HWE, essentially using the test as a tool for identifying genotyping errors. In this paper we show that 1) testing for HWE should not be used as a tool to identify genotyping errors; and 2) it is not necessary, and possibly even harmful, to test the HWE assumption before testing for association between alleles and disease. Instead one should inherently account for deviations from HWE with an adjusted chi-square test statistic, a procedure which in the present context is identical to the trend test. Examples from previous reports are used to illustrate the methodology.

The genetic approach in pulmonary fibrosis: can it provide clues to this complex disease?

Multiple investigators have undertaken genetic studies in idiopathic pulmonary fibrosis populations in attempts to define genetic links to disease in hopes that this would improve understanding of disease pathogenesis and target pathways for therapy. Multiple genes have been evaluated using a candidate gene approach with limited success, with results suggesting a disease modifier effect rather than a disease causing effect. Using this approach, associations have been observed between idiopathic pulmonary fibrosis and specific polymorphisms in genes encoding interleukin-1 receptor antagonist, tumor necrosis factor-alpha, and complement receptor 1. Recently investigators have used familial pulmonary fibrosis cohorts to evaluate for genetic mutations associated with idiopathic pulmonary fibrosis. Using one pulmonary fibrosis kindred, a mutation in the gene encoding surfactant protein C was identified as the cause of pulmonary fibrosis in this family. Subsequently, another individual with idiopathic pulmonary fibrosis was identified with a different mutation in surfactant protein C. Though rarely found in patients with idiopathic pulmonary fibrosis, these surfactant protein C mutations highlight the importance of the alveolar epithelium in disease pathogenesis. A recent collaboration between investigators at three major centers has resulted in the largest collection of families with pulmonary fibrosis to date, with hopes that this effort will identify genetic mutations associated with idiopathic pulmonary fibrosis. If genetic links to idiopathic pulmonary fibrosis are defined in this study, then the pathways involved with these genes and gene products can be targeted by investigators to help identify potential treatment options for this disease.

Racial and ethnic disparities in sarcoidosis: from genetics to socioeconomics

Sarcoidosis is a multisystem granulomatous disease of unknown cause that occurs worldwide. The clinical expression of sarcoidosis varies by race. These racial differences may be the result of genetic and socioeconomic factors. Many of these genetic associations are race-specific in that they are found in either African Americans or whites but not both. Socioeconomic differences may also explain the racial disparities between African American and white patients with sarcoidosis. Finally, the phenotypic differences be-tween races may relate to an interaction between genetics and socioeconomic factors. The influences of genetics and socioeconomic status on the development and phenotypic expression of sarcoidosis will be better understood as the mechanisms of disease development are uncovered.

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.

Polymorphisms of B7 (CD80 and CD86) Genes Do Not Affect Disease Susceptibility to Sarcoidosis

BACKGROUND

B7 proteins (CD80, CD86) are costimulatory molecules expressed on antigen-presenting cells and are essential factors for T cell activation.

OBJECTIVES

The aim of this study is to investigate the relationship of B7 gene polymorphisms either to disease susceptibility or to cell profile of bronchoalveolar lavage (BAL) fluid in Japanese sarcoidosis patients.

METHODS

Gene polymorphisms located in CD80 promoter, CD80 exon 3 and exon 8 of CD86 were examined in 146 Japanese sarcoidosis patients and 157 healthy controls using single-strand conformation polymorphism and direct sequencing. The distribution of genotypes was compared between the two groups. BAL fluid cell profiles were compared for the various genotypes of the different polymorphisms for the 62 patients who underwent BAL.

RESULTS

There were no significant differences in the distribution of genotypes or allele frequencies for all polymorphisms between sarcoidosis and controls. There were no significant differences in BAL fluid cell profiles among the different genotype groups of the various polymorphisms studied.

CONCLUSIONS

There was no relationship between the B7 gene polymorphisms studied and disease susceptibility or BAL fluid cell profiles in Japanese sarcoidosis patients.

Genomic determination of CR1 CD35 density polymorphism on erythrocytes of patients with gallbladder carcinoma

AIM

To study the changes of quantitative expression, adhering activity and genomic density polymorphism of complement types in erythrocytes (CR1) of patients with gallbladder carcinoma and the related clinical significance.

METHODS

Polymerase chain reaction (PCR), Hind III restriction enzyme digestion, quantitative assay of CR1 and adhering activity assay of CR1 in erythrocytes were used.

RESULTS

The number and adhering activity of CR1 in patients with gallbladder carcinoma (0.738+/-0.23, 45.9+/-5.7) were significantly lower than those in chronic cholecystitis and cholecystolithiasis (1.078+/-0.21, 55.1+/-5.9) and healthy controls (1.252+/-0.31, 64.2+/-7.4) (P<0.01). The number and adhering activity of CR1 in patients with chronic cholecystitis and cholecystolithiasis (1.078+/-0.21, 55.1+/-5.9) were significantly lower than those in healthy controls (1.252+/-0.31, 64.2+/-7.4) (P<0.05). There was a positive correlation between quantitative expression and adhering activity of CR1 (r = 0.79, P<0.01). Compared with those on preoperative day (0.738+/-0.23, 45.4+/-4.9), the number and adhering activity of CR1 in patients with gallbladder carcinoma decreased greatly on the third postoperative day (0.310+/-0.25, 31.8+/-5.1) (P<0.01), and on the first postoperative week (0.480+/-0.25, 38.9+/-5.2) (P<0.01), but they were increased slightly than those on the preoperative day (P>0.05). The number and adhering activity of CR1 recovered in the second postoperative week(0.740+/-0.24, 46.8+/-5.9) (P<0.01) and increased greatly in the third postoperative week (0.858+/-0.35, 52.7+/-5.8) (P<0.01) in comparison with those on the preoperative day and in the first postoperative week. The number and adhering activity of CR1 of gallbladder carcinoma patients with infiltrating, adjacent lymphogenous and distant organ metastases were significantly lower than those of gallbladder carcinoma patients without them (P<0.01). No difference was observed between the patients with gallbladder carcinoma and healthy individuals in the spot mutation rate of CR1 density gene (chi(2) = 0.521, P>0.05). The distribution of expression was 67.8% in high expression genomic type, 24.8% in moderate expression genomic type, and 7.4% in low expression genomic type. The number and adhering activity of CR1 high expression genomic type gallbladder carcinomas (0.749+/-0.22, 42.1+/-6.2) were significantly lower than those of healthy individuals (1.240+/-0.29, 63.9+/-7.2), and were also significantly lower than those of healthy individuals (0.921+/-0.23, 54.8+/-7.1), but no difference was observed between the number and adhering activity of CR1 lower expression genomic type gallbladder carcinomas (0.582+/-0.18, 44.3+/-5.5) and those of healthy individuals (0.610+/-0.20, 45.8+/-5.7) (P>0.05).

CONCLUSION

Defective expression of CR1 in gallbladder carcinoma is mostly acquired through central peripheral mechanisms. The changes in CR1 quantitative expression and adhering activity are consanguineously related to the development and metastasis in gallbladder carcinoma.

HLA-DRB1*1101: a significant risk factor for sarcoidosis in blacks and whites

Sarcoidosis is a granulomatous disorder of unknown etiology, associated with an accumulation of CD4+ T cells and a TH1 immune response. Since previous studies of HLA associations with sarcoidosis were limited by serologic or low-resolution molecular identification, we performed high-resolution typing for the HLA-DPB1, HLA-DQB1, HLA-DRB1, and HLA-DRB3 loci and the presence of the DRB4 or DRB5 locus, to define HLA class II associations with sarcoidosis. A Case Control Etiologic Study of Sarcoidosis (ACCESS) enrolled biopsy-confirmed cases (736 total) from 10 centers in the United States. Seven hundred six (706) controls were case matched for age, race, sex, and geographic area. We studied the first 474 ACCESS patients and case-matched controls. The HLA-DRB1 alleles were differentially distributed between cases and controls (P<.0001). The HLA-DRB1*1101 allele was associated (P<.01) with sarcoidosis in blacks and whites and had a population attributable risk of 16% in blacks and 9% in whites. HLA-DRB1-F(47) was the amino acid residue most associated with sarcoidosis and independently associated with sarcoidosis in whites. The HLA-DPB1 locus also contributed to susceptibility for sarcoidosis and, in contrast to chronic beryllium disease, a non-E(69)-containing allele, HLA-DPB1*0101, conveyed most of the risk. Although significant differences were observed in the distribution of HLA class II alleles between blacks and whites, only HLA-DRB1*1501 was differentially associated with sarcoidosis (P<.003). In addition to being susceptibility markers, HLA class II alleles may be markers for different phenotypes of sarcoidosis (DRB1*0401 for eye in blacks and whites, DRB3 for bone marrow in blacks, and DPB1*0101 for hypercalcemia in whites). These studies confirm a genetic predisposition for sarcoidosis and present evidence for the allelic variation at the HLA-DRB1 locus as a major contributor.

Complement receptor 1 gene polymorphisms are associated with idiopathic pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) is a chronic, fibrotic disorder underlain by aberrant wound healing of repeated lung injury. Environmental triggers and genetic background are likely to act as modifiers of the fibrotic response. Erythrocyte complement receptor 1 is a membrane protein mediating the transport of immune complexes to phagocytes. Three gene polymorphisms are related to the erythrocyte surface density of complement receptor 1 molecules, which in turn are related to the rate of immune complexes' clearance. There is evidence of association between sarcoidosis and the complement receptor 1 gene. We wondered whether IPF is associated with the complement receptor 1 gene alleles coding for a reduced molecule/erythrocyte ratio. We studied 74 patients and 166 control subjects. Three polymorphic sites of the gene, A3650G exon 22, HindIII RFLP intron 27, and C5507G exon 33, were analyzed and found to be in linkage disequilibrium. The GG genotype for the C5507G exon 33 polymorphism was significantly more common in patients with IPF than in control subjects (odds ratio = 6.232, 95% confidence interval = 2.198-18.419, p = 0.00023). The significant difference was found in both sexes. These findings agree with speculations on the role of the complement receptor 1 gene in idiopathic pulmonary fibrosis.