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215 p., La esclerosis múltiple (EM) es una enfermedad neurodegenerativa y autoinmune que a día de hoy no tiene cura. Se trata de una patología compleja que surge por una combinación de factores genéticos y ambientales. El objetivo de esta tesis es el estudio del gen ANKRD55, considerado de riesgo para la EM, así como de su correspondiente proteína. En el estudio genético se analizó el efecto de varios polimorfismos (SNPs) de ANKRD55 sobre la expresión génica. Se observaron efectos opuestos en linfocitos T CD4+ y células dendríticas derivadas de monocitos de pacientes y donantes sanos. Por otro lado, se caracterizó el interactoma proteico de ANKRD55 en cuatro líneas celulares, inmunes y neurológicas, de importancia en la patología de la EM. Entre los resultados, se identificaron proteínas de la familia 14-3-3 unidas a ANKRD55 en todos los tipos celulares analizados, y proteínas del transporte intraflagelar en la línea de microglía. Los posteriores análisis bioinformáticos, basados en los resultados experimentales, revelaron la potencial implicación de ANKRD55 en diversos mecanismos biológicos y moleculares como la sinapsis neuroinmune y la regulación del ciclo celular. Los resultados de estas tesis aumentan el conocimiento sobre el locus genético de ANKRD55 asociado a la EM y su posible función.

347 p., Multiple sclerosis (MS) is a chronic inflammatory neurological disease whose underlying cause remains uncertain and can be influenced by different environmental and genetic factors. We have studied two MS-susceptibility genes, IL22RA2 and IL12A, to better understand their regulation and relationship to MS. We demonstrated that the IL22RA2 gene gives rise to three isoforms in monocyte-derived dendritic cells (moDCs).. We also found that CD14++/CD16+ intermediate monocytes produced higher levels of IL22RA2 mRNA than classical and non-classical monocytes. Using transfected human cell lines, we demonstrated that the protein product of IL22RA2 variant 1 (IL22RA2v1), the IL-22BP isoform 1 (IL-22BPi1), was poorly secreted and largely retained in the endoplasmic reticulum (ER). We performed interactome analysis to uncover the mechanism underlying the ER retention of IL-22BPi1 and identified ER chaperones GRP78, GRP94, GRP170 and calnexin as main interactors. Structure-function analysis revealed that, like IL-22BPi2, IL-22BPi1 binds to the substrate-binding domain of GRP78 as well as to the middle domain of GRP94, and thus, we have demonstrated the domain of interaction of IL-22BPi1 and IL-22BPi2 with GRP78 and GRP94. Upon silencing of IL22RA2 expression in moDC, GRP78 levels were significantly reduced, suggesting that native IL22RA2 expression naturally contributes to upregulated GRP78 levels in these cells. Finally, we demonstrated that another variant apart from the canonical IL12A was expressed in moDCs and in different immune and epithelial cells lines. Altogether, our work highlights the relevance of the study of splicing variants of MS susceptibility genes for a better understanding of the effect of the genetic factors in the disease.

262 p., The human IL22RA2 gene co-produces three protein isoforms in dendritic cells (IL-22 binding protein isoform-1 [IL-22BPi1], -2 [IL-22BPi2], and -3 [IL-22BPi3]). Two of these, namely, IL-22BPi2 and IL-22BPi3, are capable of neutralizing the biological activity of IL-22. The function of IL-22BPi1, which differs from IL-22BPi2 through an in-frame, 32-amino-acid insertion provided by an alternatively spliced exon, remains unknown.This thesis focuses on the biochemical characterization of the three isoforms (in silico and in vitro), as well as the potential pharmacological targeting thereof. Additionally, it addresses the functionality of the non-synonymous single nucleotide polymorphism (SNP), rs28385692, which is located in IL22RA2 and has been found to be associated with multiple sclerosis (MS).El gen humano IL22RA2 coproduce tres isoformas en las células dendríticas (la isoforma-1 de la proteína de unión a la IL-22 [IL-22BPi1], la -2 [IL-22BPi2] y la -3 [IL-22BPi3]). Dos de ellas, la IL-22BPi2 y la IL-22BPi3, son capaces de neutralizar la actividad biológica de la IL-22. La función de la IL-22BPi1, que difiere de la IL-22BPi2 por una inserción de 32 aminoácidos mediante splicing alternativo, sigue siendo desconocida. El objetivo general de esta tesis es comprender la función y el destino de la IL-22BP mediante la caracterización bioquímica de sus isoformas. Los obteivos específicos son: estudiar la expresión de los transcritos de IL22RA2 y relacionarlos con la secreción de sus isoformas mediante su caracterización bioquímica, así como identificar los factores clave implicados en su plegamiento y secreción e investigar su secreción y función dentro de la célula; evaluar si las chaperonas identificadas pudieran ser utilizadas como posibles dianas terapéuticas que tuvieran efectos diferenciales en la secreción de las isoformas de IL-22BP; y determinar si la variante de riesgo de la EM, rs28385692, tiene efectos funcionales sobre las isoformas de la IL-22BP y en qué medid

[EN] Intronic single-nucleotide polymorphisms (SNPs) in the ANKRD55 gene are associated with the risk for multiple sclerosis (MS) and rheumatoid arthritis by genome-wide association studies (GWAS). The risk alleles have been linked to higher expression levels of ANKRD55 and the neighboring IL6ST (gp130) gene in CD4(+) T lymphocytes of healthy controls. The biological function of ANKRD55, its role in the immune system, and cellular sources of expression other than lymphocytes remain uncharacterized. Here, we show that monocytes gain capacity to express ANKRD55 during differentiation in immature monocyte-derived dendritic cells (moDCs) in the presence of interleukin (IL)-4/granulocyte-macrophage colony-stimulating factor (GM-CSF). ANKRD55 expression levels are further enhanced by retinoic acid agonist AM580 but downregulated following maturation with interferon (IFN)-gamma and lipopolysaccharide (LPS). ANKRD55 was detected in the nucleus of moDC in nuclear speckles. We also analyzed the adjacent IL6ST, IL31RA, and SLC38A9 genes. Of note, in healthy controls, MS risk SNP genotype influenced ANKRD55 and IL6ST expression in immature moDC in opposite directions to that in CD4(+) T cells. This effect was stronger for a partially correlated SNP, rs13186299, that is located, similar to the main MS risk SNPs, in an ANKRD55 intron. Upon analysis in MS patients, the main GWAS MS risk SNP rs7731626 was associated with ANKRD55 expression levels in CD4(+) T cells. MoDC-specific ANKRD55 and IL6ST mRNA levels showed significant differences according to the clinical form of the disease, but, in contrast to healthy controls, were not influenced by genotype. We also measured serum sgp130 levels, which were found to be higher in homozygotes of the protective allele of rs7731626. Our study characterizes ANKRD55 expression in moDC and indicates monocyte-to-dendritic cell (Mo-DC) differentiation as a process potentially influenced by MS risk SNPs.

Atherosclerosis is the main risk factor for cardiovascular disease (CVD), which is the leading cause of mortality worldwide. Atherosclerosis is initiated by endothelium activation and, followed by a cascade of events (accumulation of lipids, fibrous elements, and calcification), triggers the vessel narrowing and activation of inflammatory pathways. The resultant atheroma plaque, along with these processes, results in cardiovascular complications. This review focuses on the different stages of atherosclerosis development, ranging from endothelial dysfunction to plaque rupture. In addition, the post-transcriptional regulation and modulation of atheroma plaque by microRNAs and lncRNAs, the role of microbiota, and the importance of sex as a crucial risk factor in atherosclerosis are covered here in order to provide a global view of the disease.

Intronic single-nucleotide polymorphisms (SNPs) in the ANKRD55 gene are associated with the risk for multiple sclerosis (MS) and rheumatoid arthritis by genome-wide association studies (GWAS). The risk alleles have been linked to higher expression levels of ANKRD55 and the neighboring IL6ST (gp130) gene in CD4(+) T lymphocytes of healthy controls. The biological function of ANKRD55, its role in the immune system, and cellular sources of expression other than lymphocytes remain uncharacterized. Here, we show that monocytes gain capacity to express ANKRD55 during differentiation in immature monocyte-derived dendritic cells (moDCs) in the presence of interleukin (IL)-4/granulocyte-macrophage colony-stimulating factor (GM-CSF). ANKRD55 expression levels are further enhanced by retinoic acid agonist AM580 but downregulated following maturation with interferon (IFN)-gamma and lipopolysaccharide (LPS). ANKRD55 was detected in the nucleus of moDC in nuclear speckles. We also analyzed the adjacent IL6ST, IL31RA, and SLC38A9 genes. Of note, in healthy controls, MS risk SNP genotype influenced ANKRD55 and IL6ST expression in immature moDC in opposite directions to that in CD4(+) T cells. This effect was stronger for a partially correlated SNP, rs13186299, that is located, similar to the main MS risk SNPs, in an ANKRD55 intron. Upon analysis in MS patients, the main GWAS MS risk SNP rs7731626 was associated with ANKRD55 expression levels in CD4(+) T cells. MoDC-specific ANKRD55 and IL6ST mRNA levels showed significant differences according to the clinical form of the disease, but, in contrast to healthy controls, were not influenced by genotype. We also measured serum sgp130 levels, which were found to be higher in homozygotes of the protective allele of rs7731626. Our study characterizes ANKRD55 expression in moDC and indicates monocyte-to-dendritic cell (Mo-DC) differentiation as a process potentially influenced by MS risk SNPs.

Vascular smooth muscle cells (VSMCs) provide vital contractile force within blood vessel walls, yet can also propagate cardiovascular pathologies through proliferative and pro-inflammatory activities. Such phenotypes are driven, in part, by the diverse effects of long non-coding RNAs (lncRNAs) on gene expression. However, lncRNA characterisation in VSMCs in pathological states is hampered by incomplete lncRNA representation in reference annotation. We aimed to improve lncRNA representation in such contexts by assembling non-reference transcripts in RNA sequencing datasets describing VSMCs stimulated in vitro with cytokines, growth factors, or mechanical stress, as well as those isolated from atherosclerotic plaques. All transcripts were then subjected to a rigorous lncRNA prediction pipeline. We substantially improved coverage of lncRNAs responding to pro-mitogenic stimuli, with non-reference lncRNAs contributing 21–32% for each dataset. We also demonstrate non-reference lncRNAs were biased towards enriched expression within VSMCs, and transcription from enhancer sites, suggesting particular relevance to VSMC processes, and the regulation of neighbouring protein-coding genes. Both VSMC-enriched and enhancer-transcribed lncRNAs were large components of lncRNAs responding to pathological stimuli, yet without novel transcript discovery 33–46% of these lncRNAs would remain hidden. Our comprehensive VSMC lncRNA repertoire allows proper prioritisation of candidates for characterisation and exemplifies a strategy to broaden our knowledge of lncRNA across a range of disease states.

262 p., The human IL22RA2 gene co-produces three protein isoforms in dendritic cells (IL-22 binding protein isoform-1 [IL-22BPi1], -2 [IL-22BPi2], and -3 [IL-22BPi3]). Two of these, namely, IL-22BPi2 and IL-22BPi3, are capable of neutralizing the biological activity of IL-22. The function of IL-22BPi1, which differs from IL-22BPi2 through an in-frame, 32-amino-acid insertion provided by an alternatively spliced exon, remains unknown.This thesis focuses on the biochemical characterization of the three isoforms (in silico and in vitro), as well as the potential pharmacological targeting thereof. Additionally, it addresses the functionality of the non-synonymous single nucleotide polymorphism (SNP), rs28385692, which is located in IL22RA2 and has been found to be associated with multiple sclerosis (MS).El gen humano IL22RA2 coproduce tres isoformas en las células dendríticas (la isoforma-1 de la proteína de unión a la IL-22 [IL-22BPi1], la -2 [IL-22BPi2] y la -3 [IL-22BPi3]). Dos de ellas, la IL-22BPi2 y la IL-22BPi3, son capaces de neutralizar la actividad biológica de la IL-22. La función de la IL-22BPi1, que difiere de la IL-22BPi2 por una inserción de 32 aminoácidos mediante splicing alternativo, sigue siendo desconocida. El objetivo general de esta tesis es comprender la función y el destino de la IL-22BP mediante la caracterización bioquímica de sus isoformas. Los obteivos específicos son: estudiar la expresión de los transcritos de IL22RA2 y relacionarlos con la secreción de sus isoformas mediante su caracterización bioquímica, así como identificar los factores clave implicados en su plegamiento y secreción e investigar su secreción y función dentro de la célula; evaluar si las chaperonas identificadas pudieran ser utilizadas como posibles dianas terapéuticas que tuvieran efectos diferenciales en la secreción de las isoformas de IL-22BP; y determinar si la variante de riesgo de la EM, rs28385692, tiene efectos funcionales sobre las isoformas de la IL-22BP y en qué medid

Carotid atherosclerotic plaque rupture can lead to cerebrovascular accident (CVA). By comparing RNA-Seq data from vascular smooth muscle cells (VSMC) extracted from carotid atheroma surgically excised from a group of asymptomatic and symptomatic subjects, we identified more than 700 genomic variants associated with symptomatology (p < 0.05). From these, twelve single nucleotide polymorphisms (SNPs) were selected for further validation. Comparing genotypes of a hospital-based cohort of asymptomatic with symptomatic patients, an exonic SNP in the BIRC6 (BRUCE/Apollon) gene, rs35286811, emerged as significantly associated with CVA symptomatology (p = 0.002; OR = 2.24). Moreover, BIRC6 mRNA levels were significantly higher in symptomatic than asymptomatic subjects upon measurement by qPCR in excised carotid atherosclerotic tissue (p < 0.0001), and significantly higher in carriers of the rs35286811 risk allele (p < 0.0001). rs35286811 is a proxy of a GWAS SNP reported to be associated with red cell distribution width (RDW); RDW was increased in symptomatic patients (p < 0.03), but was not influenced by the rs35286811 genotype in our cohort. BIRC6 is a negative regulator of both apoptosis and autophagy. This work introduces BIRC6 as a novel genetic risk factor for stroke, and identifies autophagy as a genetically regulated mechanism of carotid plaque vulnerability.

Cardiovascular disease (CVD), the leading cause of mortality worldwide is primarily caused by atherosclerosis, which is promoted by the accumulation of low-density lipoproteins into the intima of large arteries. Multiple nanoparticles mimicking natural HDL (rHDL) have been designed to remove cholesterol excess in CVD therapy. The goal of this investigation was to assess the cholesterol efflux efficiency of rHDLs with different lipid compositions, mimicking different maturation stages of high-density lipoproteins (HDLs) occurring in vivo. Methods: the cholesterol efflux activity of soybean PC (Soy-PC), 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC), DPPC:Chol:1-palmitoyl-2-hydroxy-sn-glycero-3-phosphocholine (LysoPC) and DPPC:18:2 cholesteryl ester (CE):LysoPC rHDLs was determined in several cell models to investigate the contribution of lipid composition to the effectiveness of cholesterol removal. Results: DPPC rHDLs are the most efficient particles, inducing cholesterol efflux in all cellular models and in all conditions the effect was potentiated when the ABCA1 transporter was upregulated. Conclusions: DPPC rHDLs, which resemble nascent HDL, are the most effective particles in inducing cholesterol efflux due to the higher physical binding affinity of cholesterol to the saturated long-chain-length phospholipids and the favored cholesterol transfer from a highly positively curved bilayer, to an accepting planar bilayer such as DPPC rHDLs. The physicochemical characteristics of rHDLs should be taken into consideration to design more efficient nanoparticles to promote cholesterol efflux.

The IL22RA2 locus is associated with risk for multiple sclerosis (MS) but causative variants are yet to be determined. In a single nucleotide polymorphism (SNP) screen of this locus in a Basque population, rs28385692, a rare coding variant substituting Leu for Pro at position 16 emerged significantly (p = 0.02). This variant is located in the signal peptide (SP) shared by the three secreted protein isoforms produced by IL22RA2 (IL-22 binding protein-1(IL-22BPi1), IL-22BPi2 and IL-22BPi3). Genotyping was extended to a Europe-wide case-control dataset and yielded high significance in the full dataset (p = 3.17 × 10 −4). Importantly, logistic regression analyses conditioning on the main known MS-associated SNP at this locus, rs17066096, revealed that this association was independent from the primary association signal in the full case-control dataset. In silico analysis predicted both disruption of the alpha helix of the H-region of the SP and decreased hydrophobicity of this region, ultimately affecting the SP cleavage site. We tested the effect of the p.Leu16Pro variant on the secretion of IL-22BPi1, IL-22BPi2 and IL-22BPi3 and observed that the Pro16 risk allele significantly lowers secretion levels of each of the isoforms to around 50%-60% in comparison to the Leu16 reference allele. Thus, our study suggests that genetically coded decreased levels of IL-22BP isoforms are associated with augmented risk for MS

Cardiovascular disease (CVD), the leading cause of mortality worldwide is primarily caused by atherosclerosis, which is promoted by the accumulation of low-density lipoproteins into the intima of large arteries. Multiple nanoparticles mimicking natural HDL (rHDL) have been designed to remove cholesterol excess in CVD therapy. The goal of this investigation was to assess the cholesterol efflux efficiency of rHDLs with different lipid compositions, mimicking different maturation stages of high-density lipoproteins (HDLs) occurring in vivo.

Genome-wide association studies and meta-analysis have contributed to the identification of more than 200 loci associated with multiple sclerosis (MS). However, a proportion of MS heritability remains unknown. We aimed to uncover new genetic variants associated with MS and determine their functional effects. For this, we resequenced the exons and regulatory sequences of 14 MS risk genes in a cohort of MS patients and healthy individuals (n = 1070) and attempted to validate a selection of signals through genotyping in an independent cohort (n = 5138). We identified three new MS-associated variants at C-X-C motif chemokine receptor 5 (CXCR5), Ts translation elongation factor, mitochondrial (TSFM) and cytochrome P450 family 24 subfamily A member 1 (CYP24A1). Rs10892307 resulted in a new signal at the CXCR5 region that explains one of the associations with MS within the locus. This polymorphism and three others in high linkage disequilibrium mapped within regulatory regions. Of them, rs11602393 showed allele-dependent enhancer activity in the forward orientation as determined by luciferase reporter assays. Immunophenotyping using peripheral blood mononuclear cells from MS patients associated the minor allele of rs10892307 with increased percentage of regulatory T cells expressing CXCR5. This work reports a new signal for the CXCR5 MS risk locus and points to rs11602393 as the causal variant. The expansion of CXCR5+ circulating regulatory T cells induced by this variant could cause its MS association.