Metformin: A Dual-Role Player in Cancer Treatment and Prevention

Cancer continues to pose a significant global health challenge, as evidenced by the increasing incidence rates and high mortality rates, despite the advancements made in chemotherapy. The emergence of chemoresistance further complicates the effectiveness of treatment. However, there is growing interest in the potential of metformin, a commonly prescribed drug for type 2 diabetes mellitus (T2DM), as an adjuvant chemotherapy agent in cancer treatment. Although the precise mechanism of action of metformin in cancer therapy is not fully understood, it has been found to have pleiotropic effects, including the modulation of metabolic pathways, reduction in inflammation, and the regulation of cellular proliferation. This comprehensive review examines the anticancer properties of metformin, drawing insights from various studies conducted in vitro and in vivo, as well as from clinical trials and observational research. This review discusses the mechanisms of action involving both insulin-dependent and independent pathways, shedding light on the potential of metformin as a therapeutic agent for different types of cancer. Despite promising findings, there are challenges that need to be addressed, such as conflicting outcomes in clinical trials, considerations regarding dosing, and the development of resistance. These challenges highlight the importance of further research to fully harness the therapeutic potential of metformin in cancer treatment. The aims of this review are to provide a contemporary understanding of the role of metformin in cancer therapy and identify areas for future exploration in the pursuit of effective anticancer strategies.

The prevalence of CCR5-Δ32 mutation in a cohort of Saudi stem cell donors

CCR5 is a chemokine receptor that was found to be used by HIV as a co-receptor for entering target cells. A 32 bp deletion was described in certain people that rendered CCR5 non-functional. The mutant allele CCR5-Δ32 has been shown to prevent HIV infection. In addition, stem cell transplantation with the CCR5-Δ32 homozygous genotype can lead to clearance of HIV infection. In this study, our aim was to investigate the frequency of CCR5-Δ32 mutation in a cohort of stem cell donors from cord blood bank and stem cell donor registry. A total of 3025 samples were collected from healthy stem cell donors (2625) and from cord blood units (400). DNA was extracted and the CCR5 gene was amplified by polymerase chain reaction (PCR) in a light cycler system using SYBR Green dye. The mutated gene was further confirmed by direct gene sequencing. We found 38 heterozygous for CCR5-Δ32 and one homozygous CCR5 mutation (Δ32/Δ32) out of the 3025 tested individuals. We conclude that the protective CCR5-Δ32 allele appears to be rarely present in Saudi Arabia.

HLA-B50 polymorphism in the Saudi population

The HLA-B50 serologic family is very frequent in people of Arabic origin. In Saudi Arabia, HLA-B50 is the most frequent HLA-B allele. The aim of this study was to investigate the distribution of HLA-B50 alleles in healthy Saudi individuals. A total of 162 healthy Saudi individuals were selected based on low-resolution HLA typing. DNA samples were typed by sequence-based typing method for exons 2, 3 and 4 of the HLA-B locus (Genome Diagnostics B.V.). The HLA-B*50 alleles were analysed using SBT engine software. HLA-B*50:01:01 was found in 161 of 162 individuals (99.4%), while HLA-B*50:09 was found in one individual (0.6%). HLA-B*50:01:01 is the most common HLA-B50 allele in Saudi Arabia.

16(th) IHIW: global distribution of extended HLA haplotypes

This report describes the project to identify the global distribution of extended HLA haplotypes, a component of 16th International HLA and Immunogenetics Workshop (IHIW), and summarizes the initial analyses of data collected. The project aims to investigate extended HLA haplotypes, compare their distribution among different populations, assess their frequency in hematopoietic stem cell unrelated donor registries and initiate an international family studies database and DNA repository to be made publicly available. HLA haplotypes compiled in immunogenetics laboratories during the evaluation of transplant candidates and related potential donors were analysed. Haplotypes were determined using the pedigree analysis tool publicly available from the National Marrow Donor Program (NMDP) website. Nineteen laboratories from 10 countries (11 laboratories from North America, five from Asia, two from Latin America and one from Australia) contributed data on a total of 1719 families comprised of 7474 individuals. We identified 10393 HLA haplotypes, of which 1682 haplotypes included high-resolution typing at HLA-A, B, C, DRB1 and DQB1 loci. We also present haplotypes containing MICA and other HLA loci and haplotypes containing rare alleles seen in these families. The project will be extended through the 17th IHIW, and investigators interested in joining the project may communicate with the first author.

The progress test as a diagnostic tool for a new PBL curriculum

CONTEXT

The College of Medicine at King Saud bin Abdulaziz University for Health Sciences (KSAU-HS) is running a PBL-based curriculum. A progress test was used to evaluate components of the basic medical and clinical sciences curriculum.

OBJECTIVE

To evaluate the performance of students at different levels of the college of medicine curriculum through USMLE-based test that focused on basic medical and clinical sciences topics.

METHODS

The USMLE-based basic medical and clinical sciences progress test has been conducted since 2007. It covers nine topics, including: anatomy; physiology; histology; epidemiology; biochemistry; behavioral sciences, pathology, pharmacology and immunology/microbiology. Here we analyzed results of three consecutive years of all students in years 1-4.

FINDINGS

There was a good correlation between progress test results and students' GPA. Progress test results in the clinical topics were better than basic medical sciences. In basic medical sciences, results of pharmacology, biochemistry, behavioral sciences and histology gave lower results than the other disciplines.

CONCLUSIONS

Results of our progress test proved to be a useful indicator for both basic medical sciences and clinical sciences curriculum. Results are being utilized to help in modifying our curriculum.

Validity of two rapid point of care influenza tests and direct fluorecence assay in comparison of real time PCR for swine of origin Influenza virus

BACKGROUND

A novel swine origin influenza virus (S-OIV) is continue to spread worldwide and a global declaration of 2009 influenza pandemic was made by World Health Organization (WHO) June 2009, this along with approaching the winter season at the northern hemisphere, increase the interest to provide a quick, easy, affordable and available point of care testing for S-OIV.

OBJECTIVES

To determine the performance of two rapid point-of-care (POC) tests for influenza virus as well as direct fluorescence assay for the detection of the recently emerged a novel swine origin influenza virus (S-OIV).

STUDY DESIGN

A total of 143 respiratory samples which was submitted to Pathology and Laboratory Medicine at King AbdulAziz Medical City in Riyadh, Saudi Arabia from June 6th 2009 till June 28th 2009. All samples were tested in parallel using two rapid assays (BD Directigen EZ Flu®) and (TruFlu, Meridian®) as well as (Imagen Flu A/B DFA, Oxoid®) and compare it with RT-PCR. Each test's performed by different team, who were blinded for other team's result. Data gathered and we analyzed the analytical validity of each test.

RESULTS

The analytical sensitivity of the two influenza antigen detection tests for S-OIV was very low in comparison with RT-PCR, BD Directigen EZ performance was better than TruFlu test with sensitivities of 20.6% and 9.7% respectively. DFA perform much better than POC tests with sensitivity of 32.35%, specificity of 99.08% and PPV, NPV of 90% and 81.20% respectively.

CONCLUSION

The analytical sensitivity of the selected influenza A antigen detection tests for detection of S-OIV was very low, and should not be used to exclude S-OIV, DFA may be used as first line test especially during after hours or weekends, but negative results must confirmed by RT-PCR.

Epidemiologic shift in the prevalence of Hepatitis A virus in Saudi Arabia: A case for routine Hepatitis A vaccination

This study aims to determine the seroprevalence of Hepatitis A among a selected group of Saudi children and thus, identify the best immunization strategy. A school-based seroprevalence study in children 4-18 years of age attending the National Guard schools was done. Of the 25,531 children attending the National Guard schools, 2399 (10%) were randomly selected through a stratified one-stage cluster survey. The overall prevalence of HAV-IgG was 28.9%. The prevalence was almost the same in male and female (28.2% versus 29.5%, respectively). There was a gradual increase in the HAV-IgG with 7% in children (< 8 years), 14% (8-11 years), 30% (12-15 years), and 52% (> 16 years) of age. Since a substantial proportion of this pediatric population confirms a continuing decrease in anti-HAV seroconversion rates, we recommend including Hepatitis A in the schedule of routine childhood vaccinations.

TNF +489 polymorphism does not contribute to susceptibility to rheumatoid arthritis

OBJECTIVES

To determine if a tumour necrosis factor (TNF +489) polymorphism is associated with susceptibility to rheumatoid arthritis (RA).

METHODS

Two European populations were studied: 217 controls and 238 patients from the north of England and 145 controls and 179 patients from Spain. HLA-DRB1 and TNF +489 markers were typed using polymerase chain reaction based methods.

RESULTS

Strong associations were demonstrated with shared epitope (SE) encoding HLA-DRB1 alleles in the English (OR = 2.9 [2.2-3.9]) and Spanish (OR = 2.3 [1.6-3.3]) populations, however no association was found with TNF +489 alleles. Furthermore carriage of TNF +489A was not associated with the presence of radiological erosions, rheumatoid nodules or rheumatoid factor.

CONCLUSION

The role of the TNF locus in the genetic background of RA is unclear, however, our data does not support the previous reported association of the TNF +489A allele with RA susceptibility or severity.

Polymorphism in the immunoglobulin VH gene V1-69 affects susceptibility to rheumatoid arthritis in subjects lacking the HLA-DRB1 shared epitope

OBJECTIVE

To investigate the contribution of polymorphism in the immunoglobulin heavy chain variable region V1-69 gene set to genetic susceptibility to rheumatoid arthritis (RA) in Czech and British patients.

METHODS

We used V1-69 gene sequence-specific polymerase chain reaction (PCR) and restriction enzyme digestion to study polymorphism in the V1-69 gene set in germline DNA of 109 Czech and 159 British RA patients and 164 ethnically matched controls. Polymorphism was further studied by nucleotide sequencing of the V1-69 gene locus in germline DNA.

RESULTS

We found that all patients and controls had at least one V1-69 gene copy. In the Czech RA cohort, the dimorphic nucleotide in codon 73 of V1-69 (GAA or AAA) was present in the homozygous form 73(A/A) in 31 of 109 (28.4%) RA patients vs 12 of 79 (15.2%) controls [odds ratio (OR)=2.22, P<0.001]. When the RA patients and controls were classified according to HLA shared epitope (SE) status, 73(A/A) was found in 18 of 76 (23.7%) SE(+) patients compared with 13 of 38 (34.2%) SE(-) patients, four of 12 (18.2) SE(+) controls and eight of 57 (14%) SE(-) controls. This suggests that homozygosity for the dimorphic sequence 73(A) contributed to susceptibility to RA in SE(-) Czech individuals (OR=3.2, P<0.001). The most striking observation was that none of the 38 SE(-) Czech patients, compared with 11 of 76 (14.5%) SE(+) RA patients, three of 22 (13.6%) SE(+) and 11 of 57 (19.3%) SE(-) ethnically matched controls, were homozygous for the alternative dimorphic sequence 73(G/G) (OR=9.1, P<0.05). These data, however, were not replicated in a Caucasoid British RA population.

CONCLUSION

The dimorphic sequence at codon 73 (73(A/A)) of the V1-69 gene contributes to genetic susceptibility in SE(-) Czech RA patients.

Association of the A561C E-selectin polymorphism with systemic lupus erythematosus in 2 independent populations

OBJECTIVE

E-selectin is expressed on cytokine stimulated endothelial cells and plays an important role in leukocyte-endothelium interactions and inflammatory cell recruitment. The gene for E-selectin is located at chromosome 1q 23-25 within the linkage area for systemic lupus erythematosus (SLE). The best characterized polymorphism in E-selectin molecule is A561C, which codes for Ser128Arg. We studied the prevalence of the A561C E-selectin gene polymorphism in patients with SLE and controls from 3 different ethnic populations.

METHODS

Three cohorts of patients with SLE (1987 American College of Rheumatology criteria) and matching population controls were studied. These consisted of Caucasians of British Isles descent, Caucasians of Spanish origin, and Caucasians of Turkish origin. We used polymerase chain reaction and restriction fragment length polymorphism to genotype patients and controls.

RESULTS

The numbers of patients and controls in each group were: UK (113 and 148), Spanish (145 and 179), and Turkish (93 and 96), respectively. The C allele occurred more frequently in UK and Spanish patients (OR 1.76, 95% CI 1.03-3.0, p = 0.037; and OR 1.84, 95% CI 1.1-3.09, p = 0.019), but not in Turkish patients (OR 1.03, 95% CI 0.55-1.97, p = 0.91).

CONCLUSION

In 2 of 3 populations studied, the E-selectin C allele was significantly more common in SLE than in controls. E-selectin may be a susceptibility gene to SLE in these populations. Its role in disease expression and longterm outcomes such as accelerated atherosclerosis requires further study.

[Influence of genetic variation in the major histocompatibility complex on head and neck cancer susceptibility]

BACKGROUND

While cigarette smoking and alcohol consumption are risk factors for squamous cell carcinomas (SCC) of the head and neck, genetic factors are also significant. The gene of tumor necrosis factor (TNF) is located in the major histocompatibility complex class III and the cytokine has pleiotropic actions some of which are anticarcinogenic. As this gene complex is polymorphic with microsatellite markers identified it is a further candidate for head and neck cancer susceptibility.

METHODS

We used a case-control approach to study the influence of polymorphism at the A-D markers on susceptibility in 113 controls, 265 laryngeal and 123 oral cavity/pharyngeal SCC cases. Genotypes were identified on polyacrylamide gels in an automated DNA sequencer after amplification with fluorescently-labeled primers.

RESULTS

We found no differences in allele frequencies between controls and oral cavity/pharyngeal SCC cases but the frequency of B3 was greater in the laryngeal SCC cases than controls (p = 0.004, odds ratio 2.8). Homozygosity for B3 conferred an increased risk of laryngeal cancer compared with controls (p = 0.021, odds ratio 10.8).

CONCLUSIONS

The data provide the first evidence that allelism at MHC class III microsatellite markers is associated with risk to laryngeal SCC.

Characterization of a prolactin gene polymorphism and its associations with systemic lupus erythematosus

OBJECTIVE

Hyperprolactinemia is associated with systemic lupus erythematosus (SLE), but the mechanism is unknown. Prolactin is expressed in T lymphocytes and is under the control of an alternative promoter region. We characterized a G/T single-nucleotide polymorphism (SNP) at position -1149 of this promoter and assessed its prevalence in patients with SLE.

METHODS

Electrophoretic mobility shift assays (EMSAs) were performed to determine DNA protein complex formation in the prolactin promoter. Transient transfection of reporter gene constructs containing the G/T promoter alleles into the Jurkat T cell line were used to determine transcription activity. Peripheral blood lymphocytes (PBLs) were treated in vitro with phytohemagglutinin (PHA) to determine levels of prolactin messenger RNA (mRNA).

RESULTS

EMSAs indicated that binding of a GATA-related transcription factor was altered by the G/T SNP at position -1149. Transient transfection studies in Jurkat cells showed that the G allele consistently produced higher promoter activity. PHA treatment of PBLs in vitro induced a greater increment of prolactin mRNA from patients with the GG(-1149) genotype than from those with the TT(-1149) genotype. Disease association studies in a cohort of SLE patients demonstrated an increased frequency of the prolactin -1149 G allele compared with control subjects.

CONCLUSION

We found a functionally significant polymorphism that alters prolactin promoter activity and mRNA levels in the lymphocytes. Altered local prolactin production by immune cells may contribute to disease progression by affecting T cell function.

Mannose binding lectin and FcgammaRIIa (CD32) polymorphism in Spanish systemic lupus erythematosus patients

OBJECTIVE

Mannose binding lectin (MBL) and FcgammaRII (CD32) polymorphisms have both been implicated as candidate susceptibility genes in systemic lupus erythematosus (SLE). The aim of this study was to evaluate the relationship of these polymorphisms with SLE.

METHODS

We studied a cohort of 125 SLE patients from Barcelona, Spain and 138 geographically matched controls. Sequence-specific primer-polymerase chain reaction (SSP-PCR) amplification was used to determine CD32 and MBL structural polymorphisms. MBL haplotypes were established using sequence-specific oligonucleotide probing techniques.

RESULTS

Patients carried the MBL codon 54 mutant allele more frequently than controls [odds ratio (OR) 2.2; 95% confidence interval (CI) 1.2-4.0; P=0.007] and the haplotype HY W52 W54 W57 was found to be significantly lower in cases compared with controls (OR 0.6; 95% CI 0.4-0.9; P=0.016).

CONCLUSION

The MBL gene codon 54 mutant allele appears to be a risk factor for SLE, whilst haplotypes encoding for high levels of MBL are protective against the disease. Differences between controls and patients were not significant when considering the FcgammaRIIa polymorphisms; similar results were observed for renal affectation.

Identification of high and low responders to allografts

The immune response to an allograft varies from one individual to another. This individual variation is, at least in part, due to genetic variation in the regulation of cytokine gene expression. High and low cytokine responses in vitro for tumour necrosis factor-alpha (TNF-alpha), transforming growth factor-beta 1 (TGF-beta1) and other cytokines can be predicted from an individual's cytokine genotype. Using the same genetic markers we have been able to show associations, in particular between TNF-alpha genotype of the recipient and acute allograft rejection and, similarly, between TGF-beta1 genotype and chronic rejection. The ability to identify high and low responders to allografts by a simple genetic test, and to predict who will suffer acute and chronic rejection, has implications for donor selection and recipient treatment as well as for the design and interpretation of clinical trials of new immunosuppressive agents.

Anti-8-oxo-2'-deoxyguanosine phage antibodies: isolation, characterization, and relationship to disease states

We have used human single chain Fv (scFv) phage display antibody libraries to isolate recombinant antibodies against the DNA adduct 8-oxo-2'-deoxyguanosine (8-oxodG). One of these scFvs (175G) bound to several 8-oxodG-containing oligonucleotides whilst demonstrating no cross-reactivity with G-containing control oligonucleotides, and bound to 8-oxodG lesions introduced into DNA by treatment with methylene blue and white light. In addition, 175G inhibited the cleavage of an 8-oxodG-containing oligonucleotide by the Escherichia coli enzyme formamidopyrimidine-DNA glycosylase (Fpg). The nucleotide sequence of the 175G V(H) gene segment was 98% homologous to the published V(H) sequence of a human hybridoma derived from a patient with systemic lupus erythematosus (SLE). Sera from two SLE patients bound to damaged DNA, and this binding could be inhibited by 175G. The use of human scFv phage display libraries has thus produced a unique reagent with specificity for 8-oxodG, which may have a role in damage detection and quantitation and in modifying DNA repair activity. 175G also offers support to the hypothesis that SLE might be associated with oxidative damage to DNA.

Interaction between tumor necrosis factor microsatellite polymorphisms and the HLA-DRB1 shared epitope in rheumatoid arthritis: influence on disease outcome

OBJECTIVE

To investigate whether interactions between tumor necrosis factor (TNF) microsatellite polymorphisms and the HLA-DRB1 shared epitope (SE) are associated with disease severity in rheumatoid arthritis (RA), and to determine if such associations are the same in male and female patients.

METHODS

Genotyping for the TNFa microsatellite and HLA-DRB1 was carried out on 157 RA patients with established disease (duration >5 years). Disease severity measures included radiographic damage (the Larsen method), functional assessment by the Health Assessment Questionnaire, history of joint surgery, and global appraisal of outcome by means of a visual analog scale score. The association of severity measures with TNFa microsatellite polymorphisms stratified by SE status, and the interaction between TNFa and the SE, were investigated using stratified analyses and multiple or logistic regression analyses.

RESULTS

No significant associations were observed between any single TNFa microsatellite polymorphism and disease severity, although preliminary evidence for an interaction between TNFa6 and TNFa11 was obtained. In the presence of the SE, a significantly worse outcome was associated with individuals carrying TNFa6, and a significant interaction (P = 0.04-0.006) was found between these alleles for all the outcome measures examined except history of joint surgery. In the absence of the SE, the TNFa6 allele was associated with significantly better outcome scores. When examined by sex, significant associations between the TNFa6/SE haplotype and disease outcome measures were found only in females. No statistically significant interactions were found in males, although the TNFa6/SE haplotype was still associated with the worst outcome scores.

CONCLUSION

The association of the SE with disease severity in RA is influenced by an interaction with the TNFa6 microsatellite polymorphism. This interaction appears to be acting predominantly in female patients, although the trend is similar in the smaller percentage of males carrying the TNFa6/SE haplotype.

Linkage of a marker in intron D of the estrogen synthase locus to rheumatoid arthritis

OBJECTIVE

To test for the presence of linkage of the estrogen synthase (CYP19) locus to rheumatoid arthritis (RA) in affected sibling pair (ASP) families.

METHODS

Two data sets of RA ASPs (225 ASPs and 107 ASPs) were genotyped for a polymorphic tetranucleotide marker at the CYP19 locus using fluorescence-based semiautomated genotyping technology. Evidence of linkage was assessed by estimating allele sharing (identical by descent) in affected sibling pairs. The effect of this locus was also examined in patient subgroups stratified by sex and by age at disease onset.

RESULTS

An increase in allele sharing at the CYP19 locus was observed in the first data set of 225 ASPs (logarithm of odds [LOD] 0.8; P = 0.04). There was also an increase in allele sharing in a second data set, but this did not reach statistical significance (LOD 0.34; P = 0.1). The highest increase in allele sharing was seen in patients with an age at disease onset that was >50 years (LOD 1.1; P = 0.02).

CONCLUSION

An increase in allele sharing at the CYP19 locus has been demonstrated in 2 large samples of RA ASPs. The evidence for linkage was strongest in patients with an age at onset that was >50 years, which suggests that this locus may be a susceptibility locus for developing RA later in life. These data provide preliminary evidence that CYP19 may have a role in RA susceptibility.

The Bg/II polymorphism of the human prolactin gene lies within intron C and can be detected by PCR/RFLP

Prolactin has been shown to be active as an immunomodulatory hormone and is therefore of potential importance in disease progression and development. Any polymorphism in the gene and regulatory sequences may prove useful for disease association studies. A Bg/II polymorphism has been previously detected within the prolactin gene region. We have mapped this polymorphism to intron C and detected the base mutation that causes it. We have also developed a PCR-RFLP method to genotype individuals.

The spectrum of polymyalgia rheumatica in northwestern Spain: incidence and analysis of variables associated with relapse in a 10 year study

OBJECTIVE

To examine patients presenting with polymyalgia rheumatica (PMR) during a 10 year period in Northwestern Spain and to assess disease incidence and the frequency of relapses in patients diagnosed as having either isolated ("pure") PMR or PMR associated with giant cell arteritis (GCA).

METHODS

Clinical records of patients with PMR diagnosed at the Hospital Xeral Lugo from January 1987 through December 1996 were reviewed. Patients with PMR were categorized into 2 subgroups depending on the presence or absence of associated GCA. Other conditions presenting with polymyalgia symptoms or mimicking isolated PMR were excluded. These patients were followed from the time of diagnosis until either patient's death or January 1, 1998.

RESULTS

One hundred eighty-five patients were studied. The average annual incidence rates of the total group of PMR and isolated PMR were 18.67 x 10(-5) and 13.52 x 10(-5), respectively, in a population aged 50 years or older. Relapses were frequent in both isolated PMR and PMR associated with GCA. In general, they occurred when the dose of prednisone was < 7.5 mg/day or it had been discontinued. Rate of steroid tapering was significantly higher in patients with isolated PMR who had relapses. Patients with HLA-DRB1*0401 had a higher frequency of relapses. As reported in patients with PMR associated with GCA, the adjusted mortality rate in patients with isolated PMR showed no difference compared to the Spanish population aged 50 years or older.

CONCLUSION

In Northwestern Spain, PMR is a nonfatal disease with a low incidence and frequent relapses. A possible influence of HLA-DRB1*04 alleles in the development of more severe disease, with greater tendency to relapses, is suggested.

Detection of human retrovirus 5 in patients with arthritis and systemic lupus erythematosus

OBJECTIVE

To examine whether human retrovirus 5 (HRV-5) infection is associated with autoimmune rheumatic disease.

METHODS

DNA from patients with various disorders including inflammatory diseases and from normal subjects was tested by nested polymerase chain reaction (PCR) for HRV-5 proviral DNA. Positive results were confirmed by DNA sequencing.

RESULTS

HRV-5 proviral DNA was detected in 53% of synovial samples from arthritic joints, in 12% of blood samples from patients with rheumatoid arthritis (RA), and in 16% of blood samples from patients with systemic lupus erythematosus. In contrast, it was not detectable by PCR of affected tissues from patients with several other autoimmune diseases and was found in only 1 of >200 tissue specimens obtained at autopsy from non-RA patients. Sequence analysis of the amplified viral segment showed genetic variation between samples with maintenance of the open reading frame, typical of a replicating infectious retrovirus.

CONCLUSION

This is the first report of the frequent detection of HRV-5 in any disease. We propose that the possible involvement of HRV-5 in autoimmune and rheumatic disease should be investigated further.

In vitro production of IFN-gamma correlates with CA repeat polymorphism in the human IFN-gamma gene

The DNA sequence of the human IFN-gamma gene shows the presence of a variable-length CA repeat in the first intron of the gene. We investigated the allele distribution of this microsatellite region in 164 unrelated healthy individuals, and the association with interferon-gamma (IFN-gamma) production. In vitro production of IFN-gamma showed a significant correlation with the presence of allele #2.

Giant cell arteritis and polymyalgia rheumatica can be differentiated by distinct patterns of HLA class II association

OBJECTIVE

To determine whether patients with polymyalgia rheumatica (PMR) and giant cell arteritis (GCA) exhibit identical HLA class II associations.

METHODS

A case-control association study was performed on a population sample from Lugo, in Northwestern Spain. DNA samples were available for 128 patients and 145 ethnically matched controls. Within the patient group 26 exhibited both PMR and GCA, 75 PMR alone, and 27 GCA alone. HLA-DRB1, DQA1, and DQB1 phenotypes were defined by molecular based techniques.

RESULTS

HLA-DRB 1*0401 was associated with GCA regardless of PMR status, although this only reached statistical significance in the total GCA group. This was also seen for DRB 1*0101, *0102, although the association was less strong. Patients with PMR without GCA were not associated with DRB1*0401 or *0101, *0102, but exhibited a significant association with DRB1*13, *14. Nonsignificant increases in DQA1 and DQB1 phenotype frequencies appeared to reflect known patterns of linkage disequilibrium with the HLA-DRB1 alleles associated with GCA and PMR groups. An association was observed between the presence of the RA DRB1 shared epitope (SE) and GCA but not with PMR in the absence of GCA. This association was primarily accounted for by the presence of a single copy of the SE, and homozygosity for the SE did not confer additional risk. A high frequency of SE-bearing DRB1 alleles was observed in patients with GCA with jaw claudication or visual manifestations, although the sample size of these subgroups was small.

CONCLUSION

PMR and GCA in a Northwestern Spanish population have distinct HLA class II associations. HLA is unlikely to account for the observed high level of overlap in these patients, and other etiological factors may be involved.

Sjögren's syndrome: a community-based study of prevalence and impact

OBJECTIVE

Using the European Community (EC) criteria for classification Vitali et al. Arthritis Rheum 1993;36:340 7, we report the prevalence estimates of Sjogren's syndrome (SS) from a general population and present the first population data to assess the impact of the syndrome.

METHODS

A cross-sectional population-based survey performed on 1000 adults, aged 18-75 yr, randomly selected from a population register. Responders to the initial postal phase were invited for an interview. The five criteria measured at interview were: (1) the reporting of subjective oral symptoms lasting for > 3 months; (2) the reporting of subjective ocular symptoms lasting for >3 months; (3) Schirmer-I test; (4) unstimulated salivary flow; (5) autoantibodies [Ro (SS-A), La (SS-B), rheumatoid factor (RF), antinuclear antibodies (ANA)]. SS was diagnosed if at least four of these five criteria were positive. The MOS Short-form 36 (SF-36), General Health Questionnaire (GHQ) and the Health and Fatigue Questionnaire (HFQ) were completed by subjects after the interview, and scores were compared between those with and without a diagnosis of SS.

RESULTS

A total of 341 subjects completed both the postal questionnaire and home visit. A diagnosis of SS could be given to 13 subjects. After adjusting for the presence of possible bias due to non-response, our best estimate of the prevalence of SS in the study population was 33 per 1000 subjects (95% CI 22 44). The prevalence of the disorder was higher in females (38; 95% CI 27-52) and for those subjects aged > or = 55 yr (46; 95% CI 34-61). Those subjects diagnosed positively were more impaired for each of the eight dimensions of the SF-36 than those without a diagnosis, and also suffered from higher levels of depression and fatigue.

CONCLUSIONS

SS affects approximately 3-4% of adults and in the general population appears to be associated with a clinically significant impairment of a subject's health and well-being.

Linkage of cytokine genes to rheumatoid arthritis. Evidence of genetic heterogeneity

OBJECTIVE

To investigate linkage of candidate disease susceptibility genes to rheumatoid arthritis (RA) in affected sibling pair families stratified for specific clinical features.

METHOD

Two hundred RA affected sibling pair families were genotyped for informative microsatellite markers mapping within or less than 3cM from: INF alpha, INF gamma, INF beta, IL1 alpha, IL1 beta, IL1R, IL2, IL6, IL5R, IL8R, BCL2, CD40L, NOS3, NRAMP, alpha 1 anti-trypsin, and alpha 1 anti-chymotrypsin, using fluorescence based automated technology. Linkage was examined by defining allele sharing sibling pairs. This was assessed by maximum likelihood-inheritance by descent methods.

RESULTS

An increase in allele sharing was seen for IL5R in female sibling pairs (LOD 0.91, p = 0.03), for INF gamma in sibling pairs with an affected male (LOD 0.96, p = 0.03) and most significantly for IL2 in sibling pairs where one or both were persistently seronegative (LOD 1.05, p = 0.02).

CONCLUSION

Weak evidence of linkage of RA to IL5R, IFN gamma, and IL2 has been detected in clinical subsets of sibling pairs suggesting that RA is a genetically heterogeneous disease.

Influence of tumour necrosis factor microsatellite polymorphisms on susceptibility to head and neck cancer

While cigarette smoking and alcohol consumption are recognized covariates for head and neck squamous cell carcinoma (SCC), the role of genetic factors in determining individual susceptibility is unknown. The human tumour necrosis factor (TNF) region on chromosome 6p21 within the major histocompatibility complex (MHC) includes a number of immunologically important genes. Recently, five microsatellite markers have been described in the TNF locus. TNF levels vary with different TNF microsatellite alleles, and associations of these microsatellite markers with autoimmune diseases and different types of cancer have been shown. Therefore, the TNF locus represents candidate susceptibility genes for head and neck cancer. This study describes the influence of TNF a-d microsatellite polymorphisms on susceptibility to head and neck cancer by comparing the allele frequencies of 269 patients suffering from laryngeal cancer and 123 patients suffering from oral cavity pharyngeal cancer and 113 German controls. DNA was extracted from peripheral blood samples, amplified by polymerase chain reaction with fluorescently labelled primers for TNF microsatellite (a-d) and electrophoresed on polyacrylamide gels using an automated DNA sequencer. The data showed no differences in allele frequencies between controls and pharyngeal cancer patients. By contrast, the TNF b3 allele was associated with altered risk for laryngeal cancer (p = 0.0006, odds ratio 2.2). Homozygosity for TNF b3/b3 resulted in an increased risk of developing laryngeal cancer (p = 0.004, odds ratio 5.3). Susceptibility to supraglottic SCC and multiple primary tumours was mediated by the absence of the a11 allele. The data provide the first evidence that allelism at the TNF microsatellite markers alter the risk of developing SCC of the larynx.

Weak association between subjective symptoms or and objective testing for dry eyes and dry mouth: results from a population based study

OBJECTIVES

To determine associations between symptoms of dry eyes and dry mouth and objective evidence of lacrimal and salivary gland dysfunction in a population based sample. To determine associations between these elements and the presence of autoantibodies.

METHODS

A cross sectional population based survey. Subjects were interviewed and examined (Schirmer-1 test and unstimulated salivary flow) for the presence of dry eyes and mouth. Antibodies (anti-Ro [SS-A], anti-La [SS-B], rheumatoid factor, antinuclear antibody) were measured.

RESULTS

341 subjects were examined. Twenty four per cent had dry eye symptoms, 29% dry mouth symptoms, and 14% both. There was only a weak association between the presence of oral or ocular symptoms and their respective test results. Associations were strongest between dry mouth symptoms and positive test results, and in subjects under 55 years of age. There was no association between the presence of autoantibodies and either symptoms or signs of dry eyes or dry mouth.

CONCLUSION

Only weak associations were found between self reported symptoms of dry eyes and dry mouth and objective measures said to define Sjögrens syndrome in the general population. The clinical significance of these symptoms in the community needs reappraisal.

Fc gamma RIIa polymorphism in systemic lupus erythematosus

OBJECTIVES

Polymorphism of the phagocyte IgG receptor Fc gamma RIIa may modulate immune complex mediated inflammation, particularly when immune complexes contain IgG2. Previous studies suggest that this polymorphism may be an important risk factor for lupus nephritis. Fc gamma RIIa is biallelic, the alleles R and H each having a gene frequency of about 50%. Nephritis has been associated with an increased frequency of the R allele. The frequency of common Fc gamma RIIa alleles was examined in white subjects from the United Kingdom and Greek subjects with systemic lupus erythematosus (SLE) and healthy controls.

METHODS

Fc gamma RIIa genotyping was performed using a single step polymerase chain reaction technique, which differentiates the two major alleles, R and H. Two study populations were examined: (a) white subjects from the United Kingdom: 66 controls and 81 with SLE (19 of whom had renal disease) and (b) Greek: 52 controls and 42 with SLE (19 with renal disease).

RESULTS

No significant relation was observed between Fc gamma RIIa genotype and susceptibility to SLE or SLE nephritis.

CONCLUSIONS

The Fc gamma RIIa R allele does not seem to be associated with SLE (with or without renal disease) in our United Kingdom white or Greek populations.

Allelic markers close to prolactin are associated with HLA-DRB1 susceptibility alleles among women with rheumatoid arthritis and systemic lupus erythematosus

OBJECTIVE

To investigate linkage disequilibrium between HLA-DRB1 disease susceptibility alleles and microsatellite markers close to the prolactin gene, among women with rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE) and normal controls.

METHODS

DNA from 89 women with RA, 76 women with SLE, and 94 controls was typed for HLA-DRB1 status and D6S422 and D6S285, 2 highly polymorphic microsatellite markers close to the prolactin gene. RA patients were stratified by DRB1*0401 status, and SLE patients were stratified by *0301 status.

RESULTS

There was an excess frequency of D6S422*1 among SLE patients with DRB1*0301 (odds ratio [OR] 3.1). The frequency of this allele was also slightly in excess among RA patients with DRB1*0401 (OR 1.9). D6S285*5 was also in excess among female RA patients with DRB1*0401 (OR 3.5), and was slightly increased among female SLE patients with DRB1*0301. None of these alleles were found to be increased among *0401-positive or *0301-positive controls.

CONCLUSION

These data indicate that there may be linkage disequilibrium between HLA-DRB1 alleles and microsatellite marker alleles close to the prolactin gene among women with RA and SLE. This suggests the possibility of extended haplotypes encoding for HLA-DRB1 susceptibility and high prolactin production, which contribute to susceptibility to both RA and SLE.

Epitope specificity of anti-heat shock protein 65/60 serum antibodies in atherosclerosis

Levels of specific antibodies (Ab) against mycobacterial and human heat shock protein (hsp) 65/60 are increased in the sera of patients with atherosclerotic lesions and have been demonstrated to be capable of mediating endothelial cytotoxicity. To clarify the antigen epitopes recognized by these serum Abs, Ab binding to hsp65 deletion mutants (Dms), as well as to overlapping 15-mer and 8-mer hsp65 peptides, was assessed. Western blotting of hsp65 Dms indicated the presence of at least one epitope between amino acid (aa) residues 171 and 276, recognized by both high-titer sera and affinity-purified anti-hsp65/60 Ab. Fluorescence immunoassays using 53 15-mer peptides and Pin ELISA using 526 7-mer peptides demonstrated three distinct, conserved sequences with high affinity to high-titer sera and purified anti-hsp65/60 Ab. Two N-terminal sequences, aa 97-109 and aa 179-187, and one C-terminal sequence, aa 504-512, were identified. These three epitopes recognized by anti-hsp65/60 Ab may serve as autoantigens in certain circumstances in vivo. This phenomenon could contribute to the initiation of atherosclerosis by an autoimmune reaction.

A dysfunctional allele of the mannose binding protein gene associates with systemic lupus erythematosus in a Spanish population

OBJECTIVE

To determine dysfunctional mannose binding protein (MBP) status of Spanish patients with systemic lupus erythematosus (SLE) and to determine whether MBP and complement C4 null alleles contribute in an additive way to SLE susceptibility.

METHODS

The frequencies of MBP alleles (characterized by polymorphisms at codon 54 and codon 57 of exon 1) were determined by the amplification refractory mutation system-polymerase chain reaction in 50 Spanish patients with SLE and 49 matched controls. Mutant genotypes for the codon 54 mutation were confirmed using a Ban I restriction enzyme digest method. Complement C4 allotyping was achieved by agarose gel electrophoresis of neuraminidase/carboxypeptidase B digested plasma samples followed by immunofixation and staining.

RESULTS

At least one dysfunctional MBP allele, unable to activate complement, was present in 52% of patients with SLE and in 31% of controls (OR = 2.4, 95% CI 1.1-5.6). Complement C4 null alleles (either C4A or C4B) were present in 61% of patients and 43% of controls (OR = 2.1, 95% CI 0.9-4.9). A dysfunctional MBP allele and C4 null allele were present in 41% of patients and 16% of controls (OR = 3.2, 95% CI 1.2-8.1).

CONCLUSION

The presence of a dysfunctional MBP allele is a risk factor for developing SLE in this Spanish population and may affect susceptibility in an additive way with C4 null alleles.

Linkage and association studies of the natural resistance associated macrophage protein 1 (NRAMP1) locus in rheumatoid arthritis

OBJECTIVE

To determine if there is any evidence of linkage between the natural resistance associated macrophage protein gene, NRAMP1, and rheumatoid arthritis (RA).

METHODS

Two dinucleotide markers, D2S1471, a highly polymorphic marker within 160 kb of NRAMP1, and a less polymorphic marker in the promoter region of NRAMP1, have been analyzed in 115 affected sib-pair RA families (35 with 2 parents, 18 with one parent) from the Arthritis and Rheumatism Council (ARC) National Repository and an additional 85 probands from the ARC National Twin Study and 96 controls. Individuals were typed for both markers by fluorescence based semiautomated polymerase chain reaction analysis.

RESULTS

No evidence of increased allele sharing in affected sib-pairs was obtained using identity by descent (IBD), identity by state, and maximum likelihood score (MLS) analysis for the whole data set. A significant increase in allele sharing was observed with marker D2S1471 (LOD 0.74; p 0.05) in the HLA discordant subgroup using IBD and MLS-IBD. No significant differences in allele frequencies were observed for any markers in the association study.

CONCLUSION

In a subset of sib-pairs that shared one or zero HLA haplotypes, LOD scores suggestive of linkage were observed. This suggests a role for NRAMP1 polymorphism in a subset of patients who do not possess HLA susceptibility alleles.

The sensitivity of different analytical methods to detect disease susceptibility genes in rheumatoid arthritis sibling pair families

Our aim was to compare the sensitivity of 4 analytical methods to detect linkage to a known disease susceptibility locus, HLA-DRB1, in 100 rheumatoid arthritis sibling pair families with incomplete parental genotype information. Genotypes for the HLA-DRB1 and HLA-A loci were analyzed using (1) identity-by-descent (IBD), considering inheritance of maternal and paternal alleles separately; (2) maximum likelihood score-IBD (MLS-IBD), which infers missing parental genotypes; (3) identity-by-state (IBS), which does not require parental genotypes; and (4) transmission disequilibrium test (TDT), which uses affected offspring with a heterozygous parent. Due to the small number of informative meoisis for HLA-DRB1, the IBD analysis was not significant for linkage (p = 0.014). HLA-A was more informative (p = 0.0002). The MLS-IBD method for HLA-DRB1 (p = 0.00004) and HLA-A (p < or = 0.00001) was significant. Using IBS both loci gave highly significant evidence of linkage, (p < < 0.00001). The TDT detected HLA-DRB1*0401 as the allele associated with RA; no HLA-A allele was associated. Thus, sib pair families with limited parental genotypes can be used to detect disease susceptibility loci, but when selecting the method of analysis the informativeness of the markers should be taken into account.

Investigation of candidate disease susceptibility genes in rheumatoid arthritis: principles and strategies

It has been estimated that a number of non-HLA susceptibility loci exist in rheumatoid arthritis (RA), each making relatively small contributions (lambda s < 2). Previous approaches for whole genome screening are unlikely to be sufficiently sensitive to detect such loci. As the pathology of RA already indicates several molecules that may be of potential importance in disease susceptibility, we propose an alternative approach, targeting candidate genes directly. Highly polymorphic dinucleotide markers within a candidate gene sequence or close to the gene can be used as markers, and the selection of the most appropriate markers is discussed. RA sibling pair families from the Arthritis and Rheumatism Council National Repository (n = 200) are used in linkage analysis studies. The data generated are analyzed using sib pair analysis methods to examine evidence of linkage. The interpretation of such results is also discussed, in particular, minimizing the possibility of type I errors, and the interpretation of negative results.

Tumor necrosis factor microsatellite haplotypes are different in male and female patients with RA

We investigated whether tumor necrosis factor (TNF) microsatellite polymorphisms are associated with sex and age at disease onset in rheumatoid arthritis (RA). A case-control study was used to compare the frequencies of TNF microsatellite alleles in 181 Caucasian RA cases and 251 controls. TNF microsatellite genotyping was performed using fluorescent based polymerase chain reaction (PCR) techniques and HLA-DR typing using PCR based sequence specific oligonucleotide probing. The association of TNF microsatellite alleles a6, b5, and d4 with RA was confirmed. These polymorphisms were more frequent in female patients. Male patients with RA with young age at onset had a different TNF microsatellite profile, TNFa2, b1, and c2 being the most frequent. TNF microsatellite polymorphisms are different in male and female patients with RA. This difference was more obvious in patients stratified according to age at onset. Sex and age at onset should be considered in studies of genetic factors in RA.

Are both genetic and reproductive associations with rheumatoid arthritis linked to prolactin?

The risk of rheumatoid arthritis (RA) seems to be associated with reduced fecundity and with breastfeeding; these apparently contradictory risk factors can be explained by their association with high prolactin concentrations. The only consistent genetic association with RA is for genes encoded in the HLA complex, particularly HLA DR4. We have identified some data indicating that the effects of breastfeeding and nulliparity are modified by HLA DR4 status, suggesting an interaction between genetic and reproductive risk factors in the aetiology of RA. The prolactin gene is in close proximity to the HLA region on the short arm of chromosome six. We therefore propose the hypothesis that the associations between DR4 and reproductive risk factors in RA are due to linkage disequilibrium between DR4 and an abnormally regulated prolactin gene polymorphism.