Association between the HLA-DR alleles and longevity: a study in Sardinian population

Human longevity may be correlated with optimal functioning of the immune system, suggesting that genetic determinants of longevity also resides in those polymorphisms for the immune system genes that regulate immune responses as histocompatibility (HLA) antigens. However, conflicting results have been obtained. Some well planned and designed association studies performed in Caucasians suggest that longevity is associated with positive selection of alleles (i.e. HLA-DR11) or haplotypes (i.e. HLA-B8,DR3) that confer resistance to infectious diseases, respectively, via peptide presentation or via antigen non-specific control of immune response. Association studies are subjected to a number of possible confounding factors, the homogeneity of the population in term of geographical origin among others. Because of the lack of large-scale heterogeneity, the Sardinians represent a suitable population for association studies addressed to dissect the complex traits as longevity. Thus, we have evaluated, by the amplification refractory mutation system/polymerase chain reaction, HLA-DR frequencies in 120 centenarians (79 women and 41 men) and 86 controls (53 women and 33 men) from Sardinia, to validate, in this very homogeneous population, the associations between HLA alleles or haplotypes and longevity observed in other Caucasoid populations. No significant differences were obtained by analysing the differences between Centenarians and controls except for HLA-DRB1*15 that was increased in centenarians. However, the significance was not maintained by multiplying P values for the number of alleles under study. Thus, in Sardinian centenarians, we were not able to confirm the findings observed in the well planned and designed studies performed in other Caucasoid populations. Besides, HLA HFE gene polymorphisms have been recently demonstrated to be associated with longevity in the Sicilian population but not in Danish one. On the whole these findings clearly show that HLA/longevity associations are population-specific, being heavily affected by the population-specific genetic and environmental history. So, in our opinion, HLA genes might be considered survival genes not longevity genes.     

T-cell activation in HLA-B8,DR3-positive individuals early antigen expression defect in vitro

The HLA-B8,DR3 haplotype is overrepresented in several autoimmune diseases, implying that genes predisposing to these disorders are linked to this haplotype. In the patients affected by these diseases, as well as in healthy HLA-B8,DR3 individuals, various dysfunctions reflecting an impairment of T-cell activation have been found. To better characterize T-cell impairment of HLA-B8,DR3-positive healthy individuals, we analyzed the surface expression of early (CD69) and late (CD71) activation phenotypes. MNC cultures were stimulated with PHA and used for T-cell phenotyping by flow cytometry analysis. The results showed that the percentage of CD69 + T cells was significantly decreased in MNC from HLA-B8,DR3 + subjects. This defect was detected in cell cultures from all subjects studied, but it attained significance only in females in the early hours after stimulation. The difference in CD69 expression between HLA-B8,DR3-positive individuals and -negative ones was not due to differences in CD4 and CD8 ratios in the HLA-B8.DR3 cells that underwent activation, as following activation the pattern of CD4 and CD8 antigen expression was the same in both groups of subjects. Concerning the late antigen CD71, no significant difference in percentage was observed between T lymphocytes from HLA-B8,DR3 + and HLA-B8,DR3 - subjects at all the times studied. The analysis of the requirements for CD69 espression has suggested that sustained PKC activation and an increase of intracellular CA²⁺ could be responsible for TCR/CD3-mediated CD69 induction. Thus, present data suggest a defect in the signal transduction pathway of the TCR/CD3 complex. The close association that we found between the defective expression of CD69 and HLA-B8,DR3 phenotype in healthy females is consistent with data conferring to X-linked genes and/or to estrogens an important role in the development and progression of autoimmune diseases. Finally, because impaired lymphocyte activation is a common feature in autoimmune diseases, understanding the cause of the T-cell activation defect in HLA-B8,DR3-positive individuals might add an important contribution to the knowledge of the pathogenetic mechanisms that cause autoimmune diseases.     

Effects of in vitro treatment with fluticasone propionate on natural killer and lymphokine-induced killer activity in asthmatic and healthy individuals

BACKGROUND: Topical corticosteroids are beneficial in the treatment of allergic respiratory disorders; they exert effects on a number of cells involved in allergic inflammatory reactions. On the other hand, major histocompatibility complex (MHC)-unrestricted cytotoxicity (i.e., natural killer [NK] cell activity) may play a role in the inflammatory allergic reaction. The objective was to gain insight into the mechanisms of the therapeutic effects of fluticasone propionate (FP), an inhaled corticosteroid used in asthma and rhinitis therapy. Therefore, we evaluated the NK and lymphokine-activated killer (LAK) activity of effector cells in vitro treated or not with FP. METHODS: Evaluations were made on peripheral blood mononuclear cells (PBMNCs), obtained from healthy volunteers (n = 10) and from asthmatic atopic subjects (n = 10) with allergy to Parietaria. RESULTS: Asthmatic patients had significantly increased NK activity (P= 0.0008), and interleukin (IL)-2- (P=0.0005) and interferon (IFN)-alpha-induced LAK activities (P=0.0005). In both groups, FP 10(-7) M significantly reduced NK activity (P<0.0001), IL-2-induced LAK activity (P<0.0001), and IFN-alpha-induced LAK activity (P<0.0001). Similar results were obtained with FP 10(-8) M. CONCLUSIONS: Since MHC-unrestricted cytotoxicity has been implicated in the development of allergen-induced eosinophilic airway inflammation, inhibition of NK and LAK activity by FP may contribute to the steroid therapeutic effect in asthma.     

Association between platelet endothelial cellular adhesion molecule 1 (PECAM‐1/CD31) polymorphisms and acute myocardial infarction: a study in patients from Sicily

Adhesion of circulating cells to the arterial surface is among the first detectable events in atherogenesis. Cellular adhesion molecules, expressed by the vascular endothelium and by circulating leucocytes, mediate cell recruitment and their transendothelial migration. Platelet endothelial cellular adhesion molecule 1 (PECAM‐1/CD31), involved in this migration, has been associated with the developmental course of atherosclerosis. A few studies have investigated an association between coronary heart disease and single nucleotide polymorphisms (SNPs) located in functionally important domains of the PECAM‐1/CD31 gene. In particular, Ser563Asn and Gly670Arg SNPs have been described as susceptibility factors involved in acute myocardial infarction (AMI) in the Japanese male population. To confirm these observations, we studied 96 male patients (mean age 40 years; age range 20–46) affected by AMI and 118 healthy male controls (mean age 38 years, age range: 20–55), and analysed for the following PECAM‐1/CD31 SNPs: Val125Leu, Asn563Ser and Gly670Arg. The frequency of the Gly670Arg polymorphism was significantly higher in patients with AMI (58.9% vs. 48.3%; P = 0.019), whereas the frequencies of the other two SNPs (Leu125Val and Ser563Asn) were not significantly different between patients and controls. By comparing the observed number of 670Arg/Arg genotypes in the patients with the expected number, calculated from the allele frequency in a healthy population, a significance of P = 0.02 (odds ratio, 2.04; 95% CI: 1.1–3.7) was obtained, supporting a recessive model of inheritance. Hence, the differences between patients and controls are significant, but relatively small. However, as AMI is a multifactorial disease, any single mutation will only provide a small or modest contribution to the risk, which also depends on environmental interaction. All in all, we believe that the results of the present study would add support to the role of pro/anti‐inflammatory genotypes in determining susceptibility or resistance to immune‐inflammatory diseases, including atherosclerosis.     

The effect of age on mitogen responsive T cell precursors in human beings is completely restored by interleukin-2.

It is well known that the function of T lymphocytes is significantly impaired by advancing age. In the present study, attempts have been made to further characterize the T cell impairment of elderly subjects. Thus, we have performed limiting dilution microculture analysis to evaluate the precursor frequency of T lymphocytes responding to a mitogenic stimulus in old and young subjects. Furthermore we have evaluated the activity of recombinant interleukin-2 (rIL-2) on these cells. The results demonstrate that in older subjects the frequency of these precursors is significantly decreased. The in vitro treatment with rIL-2 increased the frequency of mitogen responsive T lymphocyte precursors in both groups so that the difference between the two groups was not significant. Thus present results extend the findings demonstrating that older subjects display an impairment of T cell functions and that IL-2 treatment may correct these alterations. In particular, they confirm the hypothesis that age-associated functional changes are more likely due to diminished numbers of reactive cells, than to a decline in the activity of all cells.     

Allergic rhinitis to grass pollen: Measurement of inflammatory mediators of mast cell and eosinophils in native nasal fluid lavage and in serum out of and during pollen season

Background: In allergic rhinitis, mast cells, activated by cross-linking of allergen to mast cell–bound specific IgE, release both vasoactive mediators related to the early nasal symptoms and chemotactic mediators that attract inflammatory cells, such as eosinophils, related to the late-phase response. Objective: We have analyzed, during and out of pollen season, in blood and nasal fluid from patients allergic to grass pollen, histamine and tryptase to monitor the early phase markers and eosinophil and eosinophil cationic protein (ECP) to monitor the late phase. Methods: Twenty patients were enrolled in the study. As a control, we studied 10 nonatopic subjects. Mediators and eosinophils were assessed in blood and nasal fluid. Histamine was tested only in nasal fluid. Results: During pollen season, tryptase but not histamine increased in nasal fluids from patients (2.96 vs 0.22 U/ml, p = 0.001) and correlated with symptom scores (r_s = 0.63, p = 0.003). Tryptase was not detected in serum. Eosinophils increased in nasal cytology (17.0% vs 2.0%, p = 0.001) and in the blood (26.5 vs 12.7 × 10⁶ L, p = 0.001) from patients, but they did not correlate with symptom scores. ECP increased only in the nasal lavage (16.33 vs 1.30 ng/ml, p = 0.001) and correlated with symptom scores (r_s = 0.53, p = 0.016). Conclusions: Both ECP and tryptase increase in nasal secretion in natural disease. Therefore the measurement of tryptase and ECP levels in nasal fluid might be a useful clinical test for monitoring disease activity and the effects of therapeutic agents. (J Allergy Clin Immunol 1997;100:832-7.)     

Measurement of inflammatory mediators of mast cells and eosinophils in native nasal lavage fluid in nasal polyposis.

BACKGROUND: Nasal polyposis (NP) often coexists with asthma, rhinitis and sinusitis. Polyp histology typically shows chronic, eosinophilic inflammation. The inflammatory cell infiltrate generally includes eosinophils, lymphocytes, plasma cells and mast cells. OBJECTIVE: To gain insight into the natural history of NP, we analysed mediator levels and leukocyte values in nasal fluids and eosinophil cationic protein (ECP), total IgE levels and eosinophils in the blood in several groups of both allergic and non-allergic patients with nasal polyps and in patients with allergic rhinitis (AR). METHODS: Thirty-two patients with nasal polyps entered the study. As a control group, we studied 55 patients with AR, i.e. 20 patients with seasonal AR to grass pollen, 24 with AR sensitive to Parietaria and 11 with AR sensitive to house dust mite (HDM). Eighteen patients with nasal polyps were also allergic patients (8 were sensitive to Parietaria and 10 were sensitive to HDM), whereas 14 were non-allergic patients. Tryptase and histamine values were assayed in nasal fluids, whereas total IgE was determined in serum. ECP values were assayed both in nasal fluids and serum. Eosinophils were quantified both in the blood and nasal fluids. RESULTS: Tryptase levels were significantly higher in the nasal lavages from patients with NP than in those from patients without NP (4.7 vs. 3.5 U/l, p < 0.001) and correlated with symptom scores (r(s) = 0.42, p < 0.0001). The median levels of histamine in nasal fluids from patients with NP were also significantly higher than those observed in patients without NP (50.0 vs. 21.3 ng/ml, p < 0.001), but did not correlate with symptom scores. Finally, the median levels of ECP in nasal fluids from patients with NP were significantly higher than those observed in patients without NP (38.1 vs. 16.1 ng/ml, p < 0.001) and correlated with symptom scores (r(s) = 0.38, p < 0.001). Analysis of variance showed that, among the variables studied, the presence of nasal polyps was the factor responsible for the higher levels of tryptase, histamine and ECP in nasal fluids. With regard to leukocyte counts in nasal fluids, no significant differences were observed between rhinitis patients with NP and those without NP. With regard to serum ECP and serum total IgE, no significant differences were detected between the two groups under study. Blood eosinophil levels in patients with NP were significantly higher than those observed in patients without NP (5.8 vs. 5.6, p = 0.002). Analysis of variance showed that both the presence of nasal polyps and the type of sensitisation were important. Considering the total symptom scores, no significant differences were observed between rhinitis patients with NP and those without NP. CONCLUSIONS: The present findings are consistent with the view that chronic eosinophil mucosal inflammatory disease in NP involves a self-sustaining mechanism, i.e. local release of inflammatory mediators, independent of allergen stimulation of nasal mucosa. Increased release of inflammatory mediators contributes to the development of nasal polyps, determining oedema and an increased recruitment of inflammatory cells. Besides eosinophils, mast cells also play a key role in this process.     

A genetically determined high setting of TNF-alpha influences immunologic parameters of HLA-B8,DR3 positive subjects: implications for autoimmunity.

The 8.1 ancestral haplotype (AH) is a common Caucasoid haplotype carried by most people who type for HLA-B8,DR3. It seems unique in its association with a wide range of immunopathologic diseases. Healthy subjects bearing this haplotype demonstrate several alterations of immune response. This article will focus on the identification of the mechanism(s) of disease susceptibility of 8.1 AH. In 13 carriers of 8.1 AH, and 43 negative patients, enzyme immune assays serum levels of tumor necrosis factor (TNF)-alpha, soluble endothelial leukocyte adhesion molecule-1 (sELAM-1), cortisol, and interleukin(IL)-10 were determined. In addition, quantification of cytokine produced in vitro after mitogen stimulation was studied, and all subjects were genotyped for alleles at -592, -819, and -1082 nucleotides of IL-10 gene 5' flanking region, which is known to control IL-10 production. Results revealed that 8.1 AH is associated with a high in vivo and in vitro production of TNF-alpha, which in turn seems responsible for increased serum levels of sELAM-1, cortisol, and IL-10. On the contrary, in vitro production of IL-10 is not increased in these patients and there are no differences in allele promoter frequencies between the two groups that might explain the differences in IL-10 serum values. Thus, serum values seem to be the result of the effects of increased serum levels of TNF-alpha and cortisol. In conclusion, the increased spontaneous release of TNF-alpha, which modifies a certain number of immunologic parameters, may be the most characterizing feature of 8.1 AH. The consequent modification of the immunologic scenario might be involved in the predisposition to the impressive number of diseases and the changes in immune response observed in the patients studied.