Pathogenesis of autoimmune diseases associated with 8.1 ancestral haplotype: effect of multiple gene interactions

Genetic studies have shown that individuals with certain HLA alleles have a higher risk of specific autoimmune disease than those without these alleles. Particularly, the association in all Caucasian populations of an impressive number of autoimmune diseases with genes from the HLA-B8,DR3 haplotype that is part of the ancestral haplotype (AH) 8.1 HLA-A1, Cw7, B8, TNFAB*a2b3, TNFN*S, C2*C, Bf*s, C4A*Q0, C4B*1, DRB1*0301, DRB3*0101, DQA1*0501, DQB1*0201 has been reported by different research groups. This haplotype, the more common one in northern Europe, is also associated in healthy subjects with a number of immune system dysfunctions. It has been proposed that a small number of genes within the 8.1 AH modify immune responsiveness and hence affect multiple immunopathological diseases. In this paper, the characteristic features of this haplotype that might give rise to these diverse conditions are reviewed, focusing on the role of multiple gene interactions in disease susceptibility of 8.1 AH.     

Pro-inflammatory gene variants in myocardial infarction and longevity: implications for pharmacogenomics

Inflammation and genetics play an important role in the pathogenesis of coronary heart disease (CHD). However, despite the increasing appreciation of the role of genetics in CHD and myocardial infarction (MI) pathogenesis, pharmacogenomic approaches to uncover drug target have not been extensively explored. Cyclo-oxygenases (COXs) and 5-lipoxygenase (5-LO) are the key enzymes in the conversion of arachidonic acid to prostaglandins (PG) and leukotrienes (LT) and are implicated in a wide variety of inflammatory disorders, including atherosclerosis. In fact, PGE2 activates Matrix Metallo-proteinases whereas LTB4 is a chemoactractant for monocytes and activates gene expression in inflammatory cells. We have tested the hypothesis that anti-inflammatory variants of these genes confer genetic resistance to MI and conversely favour longevity. So, we analyzed MI patients, age-related controls and centenarians. The pro-inflammatory alleles of COX-2 and 5-LO were overrepresented in MI and under-represented in centenarians whereas age-related controls displayed intermediate values. MI is a multifactorial disease, hence MI might be the result of a cumulative effect which contributes with different timing to achieve a threshold where the chance to develop the diseases is very high. In particular, differences in inflammatory status can contribute to the chance of developing a risk phenotype. However, these studies might contribute to the determination of a risk profile which may allow both the early identification of individuals susceptible to disease and the possible discovery of potential targets for drug.     

Serum levels of soluble CD23 in patients with asthma or rhinitis monosensitive to Parietaria. Its relation to total serum IgE levels and eosinophil cationic protein during and out of the pollen season.

The diagnostic value for allergies of the low affinity IgE receptor and its soluble circulating fragment (sCD23) remains unclear. In particular, little is know about seasonal influences on serum sCD23 levels in subjects with pollen allergy. In the present study, to gain insight into pathophysiological role of sCD23, we have analyzed, in blood from patients allergic to Parietaria sCD23, IgE, and eosinophil cationic protein (ECP) serum levels. IgE were assessed as atopy markers and ECP as an inflammation marker. Patients were studied during and out of pollen season, and results were compared to those obtained in nonallergic subjects. The study population included 42 nonsmoking outpatients, living in Palermo (Sicily, Italy) or in other west Sicilian towns, with a clinical diagnosis of seasonal asthma or rhinitis and monopositive skin test to Parietaria pollen. The group of asthmatic subjects consisted of 25 patients who had one or more of the usual asthma symptoms (wheezing, dyspnea, and cough) only during the pollen season. The group of rhinitis patients consisted of 17 patients, who, during pollen season, had the nasal symptoms (nasal blockage, sneezing, nasal itching, and rhinorrhoea) but no signs of asthma. As a control group, we studied 10 nonatopic subjects from laboratory staff. They had no history of seasonal or perennial rhinitis, asthma, or urticaria and had negative skin tests to a panel of allergens. Soluble CD23, IgE, and ECP were assessed in blood during and out of pollen season. Total serum IgE levels were clearly higher in atopic patients, as classically established. Concerning sCD23 serum levels, a similar pattern of results was obtained. Accordingly, significant correlations were shown between the levels of sCD23 and IgE in all groups of patients. A completely different pattern was observed by analyzing serum ECP levels because ECP levels were significantly increased only in asthmatic patients during pollen season. Accordingly, no significant correlations were observed between the levels of sCD23 and those of ECP. Identifying immune factors associated with the development of atopy can enhance our understanding of the in vivo mechanisms involved and may have utility in paradigms designed to prevent diseases. As demonstrated by the close correlation with total serum IgE values and the lack of correlation with serum ECP values, serum levels of sCD23 appear to be an additional marker for the diagnosis of atopy but not for the follow-up of allergic diseases.     

Immunoglobulin heavy chain allotypes in a sample of Sicilian patients with celiac disease

The authors have studied the immunoglobulin heavy chain allotypes in 14 Sicilian patients with celiac disease (CD) and in 75 healthy controls. No association has been found between CD and Gm or Km phenotypes. When the role of Gm phenotypes in immune response against gliadin was analyzed, fb-positive CD patients on gluten-free diet for 1 year showed an increased antigliadin IgG response. Comparing the values of fb-positive subjects with those of negative ones, a significant difference was observed. These data, demonstrating that the presence or absence of a phenotype is able to define the breadth of immune response against alpha-gliadin antigen, are indicative of the role played by Ig allotypes in CD.     

Role of the pyrin M694V (A2080G) allele in acute myocardial infarction and longevity: a study in the Sicilian population

A proinflammatory genotype seems to contribute significantly to the risk of developing coronary heart disease (CHD). Conversely, the susceptibility alleles to inflammatory disease should be infrequent in the genetic background favoring longevity. In fact, in a modern environment, attainment of longevity is facilitated by an anti-inflammatory status. To evaluate whether inflammatory alleles of pyrin, the gene responsible for familial Mediterranean fever (FMF) may play an opposite role in CHD and in longevity, we examined three FMF-associated mutations, M694V (A2080G), M694I (G2082A), and V726A (T2177C), encoded by the FMF gene (MEFV) in 121 patients affected by acute myocardial infarction (AMI), in 68 centenarians, and in 196 age-matched controls from Sicily. None of the Sicilian subjects studied carried the V726A and the M694I FMF-related mutations. The proinflammatory M694V (A2080G) mutation was the only one we found, which was over-represented significantly in CHD patients and under-represented in oldest old, and intermediate values were in healthy, young controls. After adjustment for well-recognized AMI risk factors, the M694V allele still predicted a significant risk to develop AMI. So, according to these results, we suggest that carrying the proinflammatory M694V pyrin allele may increase the risk to develop AMI. Conversely, the wild-type pyrin genotype may predispose to a greater chance to live longer in a modern environment with reduced pathogen load and improved control of severe infections by antibiotics. All these data indicate a strong relationship among inflammation, genetics, CHD, and longevity.     

Systematic review by meta-analyses on the possible role of TNF-α polymorphisms in association with Alzheimer's disease

It has been hypothesized that polymorphisms of Tumor Necrosis Factor (TNF)-α gene affect the risk of developing Alzheimer's disease (AD). However, results of different studies are often inconsistent. Our aim was to investigate by meta-analysis the association of the common polymorphisms comprehensively defining the genetic variability of the TNF-α gene with AD risk. Hence, the results being stated are of a meta-analysis across studies, and that this meta-analysis does not invalidate the results of the individual studies previously performed. Seventeen studies that investigated the association between 5 TNF-α polymorphisms (− 850, − 308, − 863, − 238, and − 1031) and AD were retrieved and analyzed. The model-free approach was applied to meta-analyze these case-control genetic association studies. Available data suggested a significant association between − 850 polymorphism and AD risk (TT vs. TC + CC: pooled odds ratio [OR], 1.61; 95% confidence interval [CI], 1.08–2.29; p = 0.02) with no evidence of between-study heterogeneity (χ², p > 0.1). Subgroup analysis suggested that the possession of T allele significantly increased the risk of AD associated with carriage of the apolipoprotein E 4 allele in Caucasian Australians and Northern Europeans (TT + TC vs. CC: OR, 1.95; 95% CI, 1.45–2.62; p = 0.00001; p > 0.1; χ² for heterogeneity, p > 0.1). No significant difference in genotype distribution of − 308 polymorphism in AD was found, with a high degree of between-study heterogeneity. For the − 863 and − 1031 polymorphisms we did not find an association with AD, but significant between-study heterogeneity discouraged genotype data pooling. Only four studies investigated the − 238 variant and the results were not significant. Current findings support an association between − 850 C > T polymorphism and the risk of developing AD; hence, they strengthen the suggestion of a potential role for anti-TNF therapy to maintain physiologic levels of TNF-α.     

Role of TLR4 receptor polymorphisms in Boutonneuse fever

The genetics of the interaction between host and microbes plays an essential role in the survival of the individual and attainment of longevity. The activation of toll-like receptor (TLR)4 plays a key role in natural and clonotypic immune responses. We evaluated whether TLR4 genotype is a component of genetic background protective versus rickettsiosis and whether this background influences longevity. We genotyped for +896A/G TLR4 polymorphism 78 patients affected with Boutonneuse fever, 78 age-matched controls and 78 advanced age individuals from Sicily. The +869G allele, that attenuates receptor signalling, was significantly overrepresented in patients in comparison with age-matched controls. By analyzing data according to gender, this allele was significantly higher in female patients when compared to advanced age women. Pro-inflammatory responses are programmed to resist fatal infections. So, it is not surprising that the genetic background of people that survive to an advanced age may be protective against infections. However, this seems to occur in women but not in men. In a previous study, the +896G TLR4 allele was overrepresented in advanced age men and underrepresented in men affected by myocardial infarction. Thus, previous and present results tend to agree with the suggestion that men and women may follow different trajectories to reach longevity. For men it might be more important to control atherogenesis, whereas for women it might be more important to control infectious diseases.