Dietary factors in relation to rheumatoid arthritis: a role for olive oil and cooked vegetables?

BACKGROUND: Although several studies showed that risk of rheumatoid arthritis (RA) is inversely associated with consumption of n-3 fatty acids, the one study showing that olive oil may have a protective role has not yet been confirmed. OBJECTIVE: We examined the relation between dietary factors and risk of RA in persons from southern Greece. DESIGN: We studied 145 RA patients and 188 control subjects who provided information on demographic and socioeconomic variables, prior medical and family history, and present disease status. Subjects responded to an interviewer-administered, validated, food-frequency questionnaire that assessed the consumption of >100 food items. We calculated chi-square statistics for linear trend and odds ratios (ORs) for the development of RA in relation to the consumption of olive oil, fish, vegetables, and a series of food groups classified in quartiles. RESULTS: Risk of developing RA was inversely and significantly associated only with cooked vegetables (OR: 0.39) and olive oil (OR: 0.39) by univariate analysis. A significant trend was observed with increasing olive oil (chi-square: 4.28; P = 0.03) and cooked vegetable (chi-square: 10. 48; P = 0.001) consumption. Multiple logistic regression analysis models confirmed the independent and inverse association between olive oil or cooked vegetable consumption and risk of RA (OR: 0.38 and 0.24, respectively). CONCLUSIONS: Consumption of both cooked vegetables and olive oil was inversely and independently associated with risk of RA in this population. Further research is needed to elucidate the underlying mechanisms of this finding, which may include the antioxidant properties or the high n-9 fatty acid content of the olive oil.

Association of MICA gene and HLA-B*5101 with Behçet's disease in Greece.

PURPOSE: Behçet's disease (BD) is known to be associated with HLA-B51 in many different ethnic groups. Recently MICA, a member of a novel family of the human major histocompatibility complex (MHC) class I genes termed MIC (MHC class I chain-related genes), was identified near the HLA-B gene, and a triplet repeat microsatellite polymorphism was found in the transmembrane (TM) region. Because a strong association with BD of one particular MICA-TM allele, A6, was shown in a Japanese population, the present study was conducted to investigate microsatellite polymorphism in Greek patients with BD to know whether this association is generally observed in BD occurring in other populations. METHODS: Thirty-eight Greek patients with BD and 40 ethnically matched control subjects were examined for MICA microsatellite polymorphism using polymerase chain reaction (PCR) and subsequent automated fragment detection by fluorescent-based technology. RESULTS: Similar to the Japanese patients with BD, the phenotype frequency of the MICA-TM A6 allele was significantly increased in the Greek patients with BD (50.0% in control subjects versus 86.8% in BD cases), with an odds ratio (OR) of 6.60 (P = 0.0012). The MICA-A6 allele was found in a high frequency both in males and females (weighted OR = 6.68; P = 0.0017). No association was found between the A6 allele and several disease features. A strong association exists between the MICA-TM A6 allele and the B*5101 allele in both the control subjects and patients with BD (weighted OR = 44.39; P = 0.0000023). CONCLUSIONS: This study revealed in Greek patients a strong association of BD with a particular MICA-TM allele, MICA-A6, providing insight into the molecular mechanism underlying the development of BD.

HLA-B*5101 in Greek patients with Behçet's disease.

Behçet's disease (BD) is a recurrent systemic vasculitis of unknown etiology. Genetic factors and infectious agents seem to be related to the etiology and pathogenesis of the disease. BD is strongly associated with HLA-B51 antigen in many ethnic groups. As there are differences in HLA profile in different ethnic groups, we designed this case-control study to examine the association of HLA-B51 alleles and BD as well as to investigate the influence of sex, age at development of the International Study Group (ISG) for Behçet's Disease criteria and certain features of disease severity on the strength of this association. The study includes 62 Greek BD patients who fulfill the ISG criteria for Behçet's disease and 87 controls. Serological HLA Class-I typing was performed by standard microlymphocytotoxicity technique. HLA-DNA typing for the B5 group was performed in all B51 subjects and controls by PCR-SSO. Allele B*5101 was found in 80% of BD patients and in 26% of controls (odds ratio (OR) 10.48, p < 10[-6]). Males who carry this allele have a higher risk than females for BD (OR 16.97 and 5.74 respectively). B*5101 predisposes to BD at a younger age in both sexes and to the development of erythema nodosum (OR = 11, p = 0.004). This was confirmed by multiple logistic regression analysis. A weak but not significant association was found between B*5101 and uveitis (OR = 2). No association was found between B*5101 and vasculitis or skin lesions in either sex. It was concluded that in the Greek population allele B*5101 is a predisposing marker for BD, as in most ethnic groups, and that this allele predisposes to the development of the disease at a younger age in both sexes and to the development of erythema nodosum.

HLA-DRB1 alleles in Greek rheumatoid arthritis patients and their association with clinical characteristics.

The association of certain HLA-DRB1 alleles in Green rheumatoid arthritis (RA) patients with several features of the disease, the gender of the patient and the age at onset was investigated. This case control study includes 86 Greek RA patients and 130 healthy controls unrelated to the patients. HLA typing was performed by polymerase chain reaction (PCR) and hybridization with sequence-specific oligonucleotide (SSO) probes. HLA-DR4 was significantly increased in RA patients. The alleles *0101, *0401, *0405 and *1001 were associated with a higher risk of RA. The *0408 allele was absent from our patients. Sixty-five per cent of RA patients carried the 'sharp epitope' (SE) compared with 31.5% of controls. The risk for RA in individuals carrying a single allele positive for SE was 2.85 times higher, and for those carrying two alleles positive for SE 8.57 times higher, than in SE-negative individuals. The risk was higher in those carrying the *0401 allele, followed by *0405 and *0101, while the genotype *0401/*0404 was absent. Alleles positive for SE comprise a predisposing factor for RA at an early age, particularly in men, and are associated with positive rheumatoid factor, nodules and erosions.

Family history as a risk factor for rheumatoid arthritis: a case-control study.

OBJECTIVE: To investigate the risk of rheumatoid arthritis (RA) in the first degree relatives and to investigate whether the sex of the parent influences the pattern of inheritance. METHODS: An interview based case-control study, with subjects serially matched for age and sex. We analyzed 126 cases (hospital cases) and 94 controls (derived from the same hospitals), who gave information for family history of RA. Data concerning RA history among siblings and parents were computerized and analyzed univariately and multivariately. RESULTS: The odds ratio (OR) for developing RA is 4.4 (p < 0.001) if a first degree relative reported having the disease and 5.4 (p < 0.01) if a female first degree relative reported having the disease. For females the OR is 7.0 (p < 0.01) if the first degree relative is female. When the analysis was restricted to parents only, it was found that mothers with RA predispose their daughters and sons to develop RA more (OR = 8.6, p < 0.01, for daughters and 4.8, p < 0.05, for both sexes) than fathers (OR = 1.1 and 1.9, respectively). CONCLUSION: This case-control study confirms the familial clustering of RA and suggests that mothers confer susceptibility to RA on their offspring more often than fathers.