Bruno Casali

Identification of multiple independent susceptibility loci in the HLA region in Behçet's disease

Behçets disease is an inflammatory disease characterized by recurrent oral and genital ulcers and significant organ involvement. Localizing the genetic association between HLA-B*51 and Behçets disease and exploring additional susceptibility loci in the human leukocyte antigen (HLA) region are complicated by the strong linkage disequilibrium in this region. We genotyped 8,572 variants in the extended HLA locus and carried out imputation and meta-analysis of 24,834 variants in 2 independent Behçets disease cohorts from 2 ancestry groups. Genotyped SNPs were used to infer classical HLA alleles in the HLA-A, HLA-B, HLA-C, HLA-DQA1, HLA-DQB1 and HLA-DRB1 loci. Our data suggest that the robust HLA-B*51 association in Behçets disease is explained by a variant located between the HLA-B and MICA genes (rs116799036: odds ratio (OR) = 3.88, P = 9.42 × 10−50). Three additional independent genetic associations within PSORS1C1 (rs12525170: OR = 3.01, P = 3.01 × 10−26), upstream of HLA-F-AS1 (rs114854070: OR = 1.95, P = 7.84 × 10−14) and with HLA-Cw*1602 (OR = 5.38, P = 6.07 × 10−18) were also identified and replicated.

Resveratrol‐mediated apoptosis of hodgkin lymphoma cells involves SIRT1 inhibition and FOXO3a hyperacetylation

Resveratrol (RSV), a plant‐derived stilbene, induces cell death in Hodgkin lymphoma (HL)‐derived L‐428 cells in a dose‐dependent manner (IC50 = 27 μM, trypan blue exclusion assay). At a lower range (25 μM), RSV treatment for 48 hr causes arrest in the S‐phase of the cell cycle, while at a higher concentration range (50 μM), apoptosis can be detected, with activation of caspase‐3. The histone/protein deacetylase SIRT1 has been described as a putative target of RSV action in other model systems, even though its role in cancer cells is still controversial. Here we show that RSV, at both concentration ranges, leads to a marked increase in p53, while a decrease of SIRT1 expression level, as well as enzyme activity, only occurred at the higher concentration range. Concomitantly, however, treatments at both concentration ranges resulted in a marked increase in K373‐acetylated p53 and lysine‐acetylated FOXO3a. Immunohistochemical stainings of human lymph nodes show a preferential distribution of SIRT1 in the germinal center of the follicles while the mantle zone shows nearly no staining to few positive cells. The classical HL‐affected lymph nodes show a strong positivity of the diagnostic Hodgkin Reed‐Sternberg cells. Notably, both the HL‐derived cell lines and the Hodgkin Reed‐Sternberg cells of the affected lymph nodes derive from germinal center‐derived B cells. The study of SIRT1 distribution and expression on a larger number of biopsies might disclose a novel role for this histone/protein deacetylase as therapeutic target.

Elevation of Angiotensin-II Type-1-Receptor Autoantibodies Titer in Primary Aldosteronism as a Result of Aldosterone-Producing Adenoma

The mechanisms of excess aldosterone secretion in primary aldosteronism (PA) remain poorly understood, although a role for circulating factors has been hypothesized for decades. Agonistic autoantibodies against type-1 angiotensin-II receptor (AT1AA) are detectable in malignant hypertension and preeclampsia and might play a role in PA. Moreover, if they were elevated in aldosterone-producing adenoma (APA) and not in idiopathic hyperaldosteronism (IHA), they might be useful for discriminating between these conditions. To test these hypotheses, we measured the titer of AT1AA in serum of 46 patients with PA (26 with APA, 20 with IHA), 62 with primary hypertension (PH), 13 preeclamptic women, and 45 healthy normotensive blood donors.We found that the AT1AA titer was higher (P<0.05) in both PA and PH patients (2.65±1.55 and 1.86±0.63, respectively) than in normotensive subjects (1.00±0.20). In APA, it was 2-fold higher than in IHA patients (3.43±1.20 versus 1.64±1.39, respectively, P<0.001), despite similar blood pressure values. Of note, it allowed effective discrimination of APA from either PH or IHA, as shown by Receiver Operator Characteristics curve analysis. Moreover, after captopril challenge, plasma aldosterone concentration fell more in AT1AA-positive than in AT1AA-negative PA patients (–32.4% [21.1–42.9] versus 0.0% [0.0–22.6], P=0.015), suggesting an agonistic role for these autoantibodies. Thus, a higher serum AT1AA titer in patients with APA than in IHA and PH patients can be useful in differentiating APA patients from either PH or IHA, and thus in selecting PA patients to be submitted to adrenal vein sampling.

Increased plasma levels of platelet-derived growth factor (PDGF-BB + PDGF-AB) in patients with never-treated mild essential hypertension

Platelet-derived growth factor (PDGF) could play a role in both vascular hypertrophy and atherosclerotic disease associated with hypertension. To assess whether plasma PDGF level is increased in mild essential hypertension, we measured plasma PDGF concentration in 25 never-treated patients with uncomplicated mild essential hypertension and in 22 normotensive healthy subjects. To evaluate the contribution of platelets to plasma PDGF in the two groups, we also measured plasma beta-thromboglobulin (BTG). Measurement of PDGF was carried out through an enzyme-linked immunoadsorbent assay, which detects two PDGF dimers, namely PDGF-BB and PDGF-AB. Both plasma PDGF and BTG were higher in the hypertensive than in the normotensive subjects. The ratio of PDGF to BTG was similar in the two groups. Plasma PDGF was weakly correlated with plasma BTG in the normotensive subjects, whereas this relationship was lost in the hypertensive patients. Our results suggest that the increase in plasma PDGF (PDGF-AB + PDGF-BB) in never-treated essential hypertension is mainly due to platelet activation. The increased circulating level of PDGF could play a role in the vascular structural changes associated with hypertension.

Inhibitor of DNA binding-1 induces mesenchymal features and promotes invasiveness in thyroid tumour cells

Characterisation of molecular mechanisms that control tumour invasion is a crucial step for the identification of molecular markers to apply in cancer diagnosis and treatment. In this work, we have investigated the role of Id1 in thyroid tumours. We demonstrate that Id1 participates to tumour progression by powering the invasion capacity of cancer cells. We prove that the overexpression of Id1 in thyroid tumour cells profoundly alters cell morphology and growth, increasing migration and invasion properties of the cells. Analysis in human thyroid tumours reveals that Id1 is expressed in invading cells and its expression is associated with an increased metastatic potential of non-anaplastic tumours. The gene expression study supports these observations demonstrating that Id1 modulates a number of genes known to control invasion, aggressiveness and pharmacological resistance in different type of human tumours. Finally, we demonstrate that the pro-invasive effect of Id1 is accompanied by the acquisition of mesenchymal features in thyroid tumour cells. This suggests that the trans-differentiation towards a more immature condition is the mechanism through which Id1 promotes thyroid tumour metastatic spreading. This study identifies Id1 as part of the pro-metastatic programme of thyroid cancer and suggests its possible utilisation as a prognostic marker.

Liddle's syndrome caused by a novel missense mutation (p617l) of the epithelial sodium channel β subunit

Objective The aim of the study was to search for mutations of SCNN1B and SCNN1G in an Italian family with apparently dominant autosomal transmission of a clinical phenotype consistent with Liddles syndrome. Methods Genetic analysis was performed in the proband, his relatives, and 100 control subjects. To determine the functional role of the mutation identified in the proband, we expressed the mutant or wild-type epithelial sodium channel in Xenopus laevis oocytes. Results A novel point mutation, causing an expected substitution of a leucine residue for the second proline residue of the conserved PY motif (PPP × Y) of the β subunit was identified in the proband. The functional expression of the mutant epithelial sodium channel in X. laevis oocytes showed a three-fold increase in the amiloride-sensitive current as compared with that of the wild-type channel. Conclusion This newly identified mutation adds to other missense mutations of the PY motif of the β subunit of the epithelial sodium channel, thus confirming its crucial role in the regulation of the epithelial sodium channel. To our knowledge, this is the first report of Liddles syndrome in the Italian population, confirmed by genetic and functional analysis, with the identification of a gain-of-function mutation not previously reported.

−344C/T polymorphism of CYP11B2 gene in Italian patients with idiopathic low renin hypertension

Most patients with low renin essential hypertension are not qualitatively different from patients with idiopathic hyperaldosteronism, as in both conditions aldosterone secretion is not appropriately reduced. The aim of the study was to investigate allele and genotype frequencies of the -344C/T polymorphism, located in the promoter region of the aldosterone synthase gene, in 83 patients with idiopathic low renin hypertension characterized by an increased aldosterone to renin ratio, including both patients with low renin essential hypertension (n=53) and subjects with idiopathic hyperaldosteronism (n=30), compared with 78 patients with normal to high renin essential hypertension and 126 normotensive control subjects. The relationship of -344C/T genotypes to basal and postcaptopril plasma aldosterone/plasma renin activity ratio was also examined in the entire hypertensive population. An increased frequency of the T allele and a relative excess of TT homozygosity over CC homozygosity were found in patients with idiopathic low renin hypertension in comparison with both normal to high renin hypertensives and normotensive controls. A higher post-captopril aldosterone to renin ratio was found in the hypertensives with TT genotype than in those with CC genotype, and TT+TC genotypes were associated with a smaller decrease in the aldosterone-to-renin ratio elicited by captopril administration. The present study suggests that the -344C/T polymorphism, or a functional variant in linkage disequilibrium with it, may play a role in the abnormal regulation of aldosterone secretion in idiopathic low renin hypertension.

CC chemokine receptor 5 polymorphism in chronic periaortitis

OBJECTIVE Chronic periaortitis (CP) is a rare disease characterized by a fibro-inflammatory tissue surrounding the abdominal aorta, and includes non-aneurysmal [idiopathic retroperitoneal fibrosis (IRF)] and aneurysmal forms [inflammatory abdominal aortic aneurysm (IAAA)]. We investigated whether CC chemokine receptor 5 (CCR5)Δ32 polymorphism confers susceptibility to CP. METHODS One hundred CP patients and 180 healthy controls were genotyped for CCR5Δ32 polymorphism by molecular methods. The patients were subgrouped according to the type of CP (IRF or IAAA) and the presence of established atherosclerotic disease (ischaemic heart disease, cerebrovascular disease and peripheral arterial disease). RESULTS The distribution of the CCR5Δ32 genotype differed between CP patients and controls (P = 0.01). The CCR5Δ32 allele was more frequent in CP patients than in controls [P = 0.02, odds ratio (OR) 2.8 (95% CI 1.2, 6.4)]. The distribution of the CCR5Δ32 genotype did not differ significantly between IRF patients and controls, whereas the CCR5Δ32 allele was more frequent in IAAA patients than in controls [P = 0.0001, OR 10.0 (95% CI 3.7, 27.3)]. Furthermore, the CCR5Δ32 allele occurred more frequently in IAAA than in IRF patients [P = 0.001, OR 6.4 (95% CI 2.1, 19.1)]. The CCR5Δ32 allele frequency was higher in IAAA patients without established atherosclerotic disease compared with controls [66.7 vs 5.6%, P = 0.00001, OR 34.0 (95% CI 7.4, 156.3)], but not in IAAA patients with atherosclerotic disease and IRF patients with or without atherosclerotic disease. CONCLUSIONS The CCR5Δ32 polymorphism might be associated with an increased risk of developing the aneurysmal form of CP, IAAA, particularly in patients without established atherosclerotic disease. Chemokines may have a role in the pathophysiology of CP.

Hereditary spastic paraplegia and axonal motor neuropathy caused by a novel SPG3A de novo mutation

Mutations in the SPG3A gene (atlastin protein) cause approximately 10% of autosomal-dominant hereditary spastic paraplegia. Most patients with an SPG3A mutation present with a pure phenotype and early-onset disease, although complicated forms with peripheral neuropathy are also reported. We report a new heterozygous S398F mutation in exon 12 of the SPG3A gene causing a very early-onset spastic paraplegia in association with motor axonal neuropathy in a 4-year-old girl resembling diplegic cerebral palsy.

Differential effects of anti-TNF-α drugs on fibroblast-like synoviocyte apoptosis

OBJECTIVE Novel drugs targeting TNF-alpha are available for treatment of RA. Fibroblast-like synoviocytes (FLSs) play a fundamental role in RA progression, through their expansion caused in part by resistance to cell death induction. The aim of our study was to determine the effects of different anti-TNF-alpha agents on FLS apoptosis. METHODS FLS from patients with either RA or OA were co-cultured with peripheral blood mononuclear cells (PBMCs), and incubated with various drugs for 6 days. Subsequently, apoptosis induction was detected by Nucleosome ELISA and terminal deoxynucleotidyl transferase dUTP nick end labeling. Western blot was used to determine the activation of the phosphatase and tensin homologue deleted on chromosome 10 (PTEN)-focal adhesion kinase (FAK) pathway as well as Bax and Bcl-2 levels. Immunoprecipitation was used for studying phosphorylation of transmembrane TNF-alpha (tmTNF-alpha). RESULTS All the tested drugs induced apoptosis of FLSs in the presence of PBMCs obtained from the same patient only when the two cell populations were in direct contact by activating the PTEN-FAK pathway and increasing Bax levels. This effect was not due to antibody-dependent cell-mediated cytotoxicity. Only the two antibodies infliximab and adalimumab were able to up-regulate Bcl-2. CONCLUSIONS Etanercept is more effective in inducing FLS apoptosis compared with the other drugs tested. This induction is dependent on the presence of PBMCs, and involves the activation of PTEN-FAK pathway. Bcl-2 increase induced by the monoclonal antibodies infliximab and adalimumab may play a protective role and thus counteract their pro-apoptotic effect on FLSs.