Carmen Arnal

Microarray analysis of hepatic gene expression identifies new genes involved in steatotic liver

Trans-10, cis-12-conjugated linoleic acid (CLA)-enriched diets promote fatty liver in mice, while cis-9, trans-11-CLA ameliorates this effect, suggesting regulation of multiple genes. To test this hypothesis, apoE-deficient mice were fed a Western-type diet enriched with linoleic acid isomers, and their hepatic gene expression was analyzed with DNA microarrays. To provide an initial screening of candidate genes, only 12 with remarkably modified expression between both CLA isomers were considered and confirmed by quantitative RT-PCR. Additionally mRNA expression of 15 genes involved in lipid metabolism was also studied. Ten genes (Fsp27, Aqp4, Cd36, Ly6d, Scd1, Hsd3b5, Syt1, Cyp7b1, and Tff3) showed significant associations among their expressions and the degree of hepatic steatosis. Their involvement was also analyzed in other models of steatosis. In hyperhomocysteinemic mice lacking Cbs gene, only Fsp27, Cd36, Scd1, Syt1, and Hsd3b5 hepatic expressions were associated with steatosis. In apoE-deficient mice consuming olive-enriched diet displaying reduction of the fatty liver, only Fsp27 and Syt1 expressions were found associated. Using this strategy, we have shown that expression of these genes is highly associated with hepatic steatosis in a genetic disease such as Cbs deficiency and in two common situations such as Western diets containing CLA isomers or a Mediterranean-type diet. Conclusion: The results highlight new processes involved in lipid handling in liver and will help to understand the complex human pathology providing new proteins and new strategies to cope with hepatic steatosis.

IL2RA/CD25 Gene Polymorphisms: Uneven Association with Multiple Sclerosis (MS) and Type 1 Diabetes (T1D)

Background IL-2 receptor (IL2R) alpha is the specific component of the high affinity IL2R system involved in the immune response and in the control of autoimmunity. Methods and Results Here we perform a replication and fine mapping of the IL2RA gene region analyzing 3 SNPs previously associated with multiple sclerosis (MS) and 5 SNPs associated with type 1 diabetes (T1D) in a collection of 798 MS patients and 927 matched Caucasian controls from the south of Spain. We observed association with MS in 6 of 8 SNPs. The rs1570538, at the 3′- UTR extreme of the gene, previously reported to have a weak association with MS, is replicated here (P = 0.032). The most associated T1D SNP (rs41295061) was not associated with MS in the present study. However, the rs35285258, belonging to another independent group of SNPs associated with T1D, showed the maximal association in this study but different risk allele. We replicated the association of only one (rs2104286) of the two IL2RA SNPs identified in the recently performed genome-wide association study of MS. Conclusions These findings confirm and extend the association of this gene with MS and reveal a genetic heterogeneity of the associated polymorphisms and risk alleles between MS and T1D suggesting different immunopathological roles of IL2RA in these two diseases.

Efficacy of bioactive compounds from extra virgin olive oil to modulate atherosclerosis development.

As olive oil is the main source of calories in the Mediterranean diet, a great deal of research has been devoted to characterizing its role in atherosclerosis. Virgin olive oil is an oily matrix that contains hydrocarbons, mainly squalene; triterpenes such as uvaol, erythrodiol, oleanolic, and maslinic acid; phytosterols; and a wide range of phenolic compounds comprising simple phenols, flavonoids, secoiridoids, and lignans. In this review, we analyze the studies dealing with atherosclerosis and olive oil in several species. A protective role of virgin olive oil against atherosclerosis has been shown in ApoE-deficient mice and hamsters. In the former animal, sex, dose, and dietary cholesterol are modulators of the outcome. Contradictory findings have been reported for rabbits, a circumstance that could be due to the profusion of experimental designs, differing in terms of doses and animal strains, as well as sources of olive oils. This role has yet to be fully validated in humans. Minor components of olive oil have been shown to be involved in atherosclerosis protection. Nevertheless, evidence of the potential of isolated compounds or the right combination of them to achieve the antiatherosclerotic effect of virgin olive oil is inconclusive and will undoubtedly require further experimental support.

Multiple Sclerosis Risk Variant HLA-DRB1*1501 Associates with High Expression of DRB1 Gene in Different Human Populations

The human leukocyte antigen (HLA) DRB1*1501 has been consistently associated with multiple sclerosis (MS) in nearly all populations tested. This points to a specific antigen presentation as the pathogenic mechanism though this does not fully explain the disease association. The identification of expression quantitative trait loci (eQTL) for genes in the HLA locus poses the question of the role of gene expression in MS susceptibility. We analyzed the eQTLs in the HLA region with respect to MS-associated HLA-variants obtained from genome-wide association studies (GWAS). We found that the Tag of DRB1*1501, rs3135388 A allele, correlated with high expression of DRB1, DRB5 and DQB1 genes in a Caucasian population. In quantitative terms, the MS-risk AA genotype carriers of rs3135388 were associated with 15.7-, 5.2- and 8.3-fold higher expression of DQB1, DRB5 and DRB1, respectively, than the non-risk GG carriers. The haplotype analysis of expression-associated variants in a Spanish MS cohort revealed that high expression of DRB1 and DQB1 alone did not contribute to the disease. However, in Caucasian, Asian and African American populations, the DRB1*1501 allele was always highly expressed. In other immune related diseases such as type 1 diabetes, inflammatory bowel disease, ulcerative colitis, asthma and IgA deficiency, the best GWAS-associated HLA SNPs were also eQTLs for different HLA Class II genes. Our data suggest that the DR/DQ expression levels, together with specific structural properties of alleles, seem to be the causal effect in MS and in other immunopathologies rather than specific antigen presentation alone.

Understanding the role of dietary components on atherosclerosis using genetic engineered mouse models.

The generation by genetic engineering of two murine models to investigate atherosclerosis, such as the apoE- and LDLr- deficient mice, is providing an extraordinaire knowledge of the effect of different nutrients on this complex disease. The present revision provides a comprehensive overview of the advances in this field that point to a remarkable complexity. While some controversies over puzzling results could be explained invoking potential nutrient interactions or different food sources of nutrients, it also appears that other factors such as sex, genetic background or immunological status are emerging as generators of differential responses to nutrients during the atherosclerotic process.

The T244I variant of the interleukin-7 receptor-alpha gene and multiple sclerosis

Several but not all studies have provided evidence for the association between multiple sclerosis (MS) and the T244I variant of the interleukin-7 receptor-alpha gene (IL7RA), rs6897932. We performed a new replication case-control study in 599 MS patients and 594 healthy controls, all Caucasians from the south of Spain. The genotype and allele frequencies differed between MS cases and controls. The IL7RA rs6897932 C allele and the CC genotype were found to be factors for disease susceptibility [per allele odds ratio (OR) 1.32, 95% CI 1.1-1.6, P=0.0031; per CC genotype vs TT + TC genotypes, OR 1.5, 95% CI 1.18-1.87, P=0.0007]. The combined data analysis included 3324 cases and 5032 controls of Europeans and Americans of European origin resulting in stronger association with similar OR (P=1.9 x 10E-9). These findings in our sample support previous reported association studies between IL7RA rs6897932 and MS.

Multiple sclerosis association study with the TENR-IL2-IL21 region in a Spanish population

Polymorphisms from the TENR-IL2-IL21 block in the 4q27 chromosome were recently associated with type 1 diabetes, celiac disease, rheumatoid arthritis and psoriasis. We undertook this study to investigate the potential role of polymorphisms rs3136534, rs6822844 and rs2069762 (-330 T/G IL2) in multiple sclerosis (MS) (805 patients of Spanish Caucasian origin and 952 health controls). We did not find evidence for association with any single nucleotide polymorphisms (SNPs) tested. Allele and genotype frequencies of the SNPs, which were studied, were similar in DRB1*15-positive or DRB1*15-negative patients. After stratification of MS patients by clinical course, a weak association was observed with rs2069762 G allele and haplotype bearing this allele with secondary progressive MS, although these cases represent 22% of the MS cases. Our results did not show major influence of TENR-IL2-IL21 locus on susceptibility or disease progression in MS. However, we could not exclude completely the effect in MS for this region. Additional studies, using much larger sample sizes and analysis of additional polymorphisms in the gene and its flanking region, will be required to ascertain their contributions to MS susceptibility.

Tag-SNP analysis of the GFI1-EVI5-RPL5-FAM69 risk locus for multiple sclerosis

A recent genome-wide association study conducted by the International Multiple Sclerosis Genetic Consortium (IMSGC) identified, among others, a number of putative multiple sclerosis (MS) susceptibility variants at position 1p22. Twenty-one SNPs positively associated with MS were located at the GFI-EVI5-RPL5-FAM69A locus. In this study, we performed an analysis and fine mapping of this locus, genotyping eight Tag-SNPs in 732 MS patients and 974 controls from Spain. We observed an association with MS in three of eight Tag-SNPs: rs11804321 (P=0.008, OR=1.29; 95% CI=1.08–1.54), rs11808092 (P=0.048, OR=1.19; 95% CI=1.03–1.39) and rs6680578 (P=0.0082, OR=1.23; 95% CI=1.07–1.41). After correcting for multiple comparisons and using logistic regression analysis to test the addition of each SNP to the most associated SNPs, we observed that rs11804321 alone was sufficient to model the association. This Tag-SNP captures two SNPs in complete linkage disequilibrium (r2=1), both located within the 17th intron of the EVI5 gene. Our findings agree with the corresponding data of the recent IMSGC study and present new genetic evidence that points to EVI5 as a factor of susceptibility to MS.

Extra virgin olive oil intake delays the development of amyotrophic lateral sclerosis associated with reduced reticulum stress and autophagy in muscle of SOD1G93A mice

Amyotrophic lateral sclerosis is a neurodegenerative disease associated with mutations in antioxidant enzyme Cu/Zn-superoxide dismutase 1. Albeit there is no treatment for this disease, new insights related to an exacerbated lipid metabolism have been reported. In connection with the hypermetabolic lipid status, the hypothesis whether nature of dietary fat might delay the progression of the disease was tested by using a transgenic mouse that overexpresses the human SOD1G93A variant. For this purpose, SOD1G93A mice were assigned randomly to one of the following three experimental groups: (1) a standard chow diet (control, n=21), (2) a chow diet enriched with 20% (w/w) extra virgin olive oil (EVOO, n=22) and (3) a chow diet containing 20% palm oil (palm, n=20). They received the diets for 8 weeks and the progression of the disease was assessed. On the standard chow diet, average plasma cholesterol levels were lower than those mice receiving the high-fat diets. Mice fed an EVOO diet showed a significant higher survival and better motor performance than control mice. EVOO group mice survived longer and showed better motor performance and larger muscle fiber area than animals receiving palm. Moreover, the EVOO-enriched diet improved the muscle status as shown by expression of myogenic factors (Myod1 and Myog) and autophagy markers (LC3 and Beclin1), as well as diminished endoplasmic reticulum (ER) stress through decreasing Atf6 and Grp78. Our results demonstrate that EVOO may be effective in increasing survival rate, improving motor coordination together with a potential amelioration of ER stress, autophagy and muscle damage.

Cystathionine β-synthase deficiency causes infertility by impairing decidualization and gene expression networks in uterus implantation sites

Hyperhomocysteinemia has been reported in human reproduction as a risk factor for early pregnancy loss, preeclampsia, and congenital birth defects like spina bifida. Female infertility was also observed in cystathionine beta synthase-deficient mice (Cbs-KO) as an animal model for severe hyperhomocysteinemia. The aim for the present research was to elucidate the time-point of pregnancy loss and to pinpoint gene and cellular changes involved in the underlying pathological mechanism. By mating 90-day-old wild-type and Cbs-KO female mice with their homologous male partners, we found that pregnancy loss in Cbs-KO occurred between the 8th and 12th gestation day during placenta formation. DNA microarrays were carried out on uterus from implantation and interimplantation samples obtained on day 8. The results allowed us to select genes potentially involved in embryo death; these were individually confirmed by RT-qPCR, and their expressions were also followed throughout pregnancy. We found that changes in expression of Calb1, Ttr, Expi, Inmt, Spink3, Rpgrip1, Krt15, Mt-4, Gzmc, Gzmb, Tdo2, and Afp were important for pregnancy success, since a different regulation in Cbs-KO mice was found. Also, differences in relationships among selected genes were observed, indicating a dysregulation of these genes in Cbs-KO females. In conclusion, our data provide more information on the gene expression cascade and its timely regulated process required for a successful pregnancy. In addition, we unveil new potential avenues to explore further investigations in pregnancy loss.