En Guadeloupe, la prévalence du diabète est deux fois plus élevée qu'en France hexagonale, avec une prédominance féminine. En dehors des facteurs environnementaux, la vitamine D et certains polymorphismes de gènes impliqués dans son métabolisme seraient associés à un risque de pathologies métaboliques. Les androgènes sont également associés aux anomalies du métabolisme glucidique, soit directement, soit via leur transporteur SHBG (Sex Hormone Binding Protein). Nous avons émis les hypothèses de recherche suivantes: 11 le statut en vitamine D et les polymorphismes des gènes impliqués dans son métabolisme pourraient être associés aux paramètres métaboliques chez des sujets Afro-Caribéens (AC). Ils expliqueraient l'importance des pathologies cardiométaboliques en Guadeloupe. 2/ la SHBG pourrait être associée aux anomalies du métabolisme glucidique, indépendamment des stéroïdes sexuels. Nos travaux sont présentés dans 4 études. Nous avons mis en évidence une prévalence élevée du déficit en vitamine D chez les sujets AC diabétiques de type 2. Nous avons trouvé une association significative entre le statut vitaminique D et le risque cardiométabolique chez ces sujets, mais aussi dans une population de sujets en hémodialyse chronique. Les polymorphismes des gènes impliqués dans le métabolisme de la vitamine D sont aussi associés à ce risque. Chez les sujets dysmétaboliques, une relation entre la SHBG, la graisse intra-hépatique, les hépatokines et les paramètres métaboliques a été mise en évidence, indépendamment des stéroïdes sexuels. En conclusion, la vitamine D et la SHBG pourraient être des marqueurs d'intérêt pour le dépistage des sujets à haut risque cardiométabolique. / In Guadeloupe, the prevalence of diabetes is two times higher than in Metropolitan France, with a female predominance. Apart from environmental factors, vitamin D and polymorphisms of genes involved in vitamin D metabolism would be associated with increased risk of metabolic diseases. Androgens are also associated with abnormal glucose metabolism, directly or through the Sex Hormone Binding Protein (SHBG). Our main hypotheses were: 11 Vitamin D status and polymorphisms of genes involved in its metabolism may be associated with metabolic pammeters in Afro-Caribbean (AC). They could explain the importance of cardiometabolic diseases in Guadeloupe. 2/ SHBG may be associated with abnormal glucose metabolism, independently of sex steroids. Our research is presente<! in four studies. We have demonstrated a high prevalence of vitamin D deficiency in AC patients with type 2 diabetes. We found a significant association between vitamin D status and cardiometabolic risk in these subjects, but also in a population of patients undergoing in chronic hemodialysis. Polymorphisms in genes involved in vitam in D metabolism are also associated with this risk, In dysmetabolic patients, a relationship between SHBG, intmhepatic fat, hépatokines and metabolic parameters was demonstrated, independently of sex steroids hormones. In conclusion, vitamin D and SHBG may be markers of interest for screening patients at high cardiometabolic risk.

Chemotherapy in childhood cancer patients is associated with reduced bone density that can result in osteoporotic fracture in survivors. A significant proportion of paediatric patients experience a reduction in plasma 25 - hydroxyvitamin D3 [ 25 ( OH ) D3 ] and 1,25 - dihydroxyvitamin D3 [ 1,25 ( OH ) 2D3 ] levels during treatment, the basis of which is unknown. A balance between the bioactivation and degradation of 1,25 ( OH ) 2D3 is responsible for maintaining homoeostatic levels of 1,25 ( OH ) 2D3 at the correct set - point. Whereas the cytochrome P450 enzyme, CYP27B1 ( 25 - hydroxyvitamin D3 1 α - hydroxylase ), catalyses the hydroxylation of the precursor 25 ( OH ) D3 to generate 1,25 ( OH ) 2D3, catabolic inactivation and cleavage of 1,25 ( OH ) 2D3 is achieved by the mitochondrial cytochrome P450 enzyme, 25 - hydroxyvitamin D3 24 - hydroxylase ( CYP24 ), which is highly expressed in bone and kidney cells. Since many of the signalling pathways which regulate the expression of CYP24 are also activated by chemotherapeutic drugs, we hypothesised that the drugs could cause the degradation of plasma 25 ( OH ) D3 and 1,25 ( OH ) 2D3 by increasing CYP24 expression, the principal means of facilitating the bio - inactivation and degradation of plasma 25 ( OH ) D3 and 1,25 ( OH ) 2D3. Using the kidney cell - lines, COS - 1 and HEK293T cells, we now report that chemotherapeutic drugs, represented by daunorubicin hydrochloride ( an anthracycline antibiotics ), etoposide and vincristine sulphate ( vinca alkaloids and related compounds ) and cisplatin ( an alkylating agent ), were able to enhance CYP24 promoter activity in kidney cell lines transfected with a CYP24 promoter - luciferase construct, either by themselves or in the presencedaunorubicin hydrochloride and etoposide, two of the strongest inducers of CYP24 promoter activation under our experimental conditions, demonstrate that these drugs acted in a concentration - dependent manner. In addition to stimulating promoter activity on their own, the drugs also amplified the induction of the CYP24 promoter by 1,25 ( OH ) 2D3. Synergistic increases were generally observed when the cells were treated simultaneously with 1,25 ( OH ) 2D3 and a drug. The two kidney cell lines generally responded in a similar manner when challenged with the drugs, either in the presence or absence of 1,25 ( OH ) 2D3. Interestingly, the hydroxylated derivative of daunorubicin hydrochloride, doxorubicin hydrochloride which is also a commonly used chemotherapeutic drug, had no effect of promoter activity. Further studies with daunorubicin hydrochloride demonstrated that the effects of the drug per se were not mediated by oxidative stress and the vitamin D receptor was not required for daunorubicin hydrochloride per se to stimulate CYP24 promoter activity. However, daunorubicin hydrochloride caused a modest increase in the expression of the vitamin D receptor and this could contribute to its synergistic activity with 1,25 ( OH ) 2D3. In the presence of etoposide, there was also a tendency for the kidney cells to express higher levels of the vitamin D receptor. A key role for the extracellular signal - regulated protein kinase ( ERK ) 1, ERK2 and ERK5 mitogen - activated protein ( MAP ) kinases was demonstrated for the inductive action of daunorubicin hydrochloride and etoposide, with CYP24 promoter - specific transcription factors located in the first - 298bp being likely targets of the ERK activity. Studies with a dominant negative mutant of MKK4, one of the two immediate upstream activators of the c - jun N - terminal kinase isoforms, demonstrated that this MAP kinase also played a crucial role in inductive actions of the of 1,25 ( OH ) 2D3. Dose - response studies with drugs. Consistent with their use in anti - cancer therapy, all of the above drugs killed the human promyelocytic HL60 leukaemic cells at very low concentrations but had no effect on the viability of kidney or liver cells, either at concentrations used in our experiments or at higher levels. Our data provide novel biochemical evidence that some of the commonly used chemotherapeutic drugs could cause an increase in the transcriptional activation of the promoter, most likely via the MAP kinases activating the transcription factors which bind to the CYP24 promoter. Such an effect could contribute to the reduction in plasma 25 ( OH ) D3 and 1,25 ( OH ) 2D3 in some of the patients undergoing chemotherapy. / Thesis (Ph.D.)--School of Paediatrics and Reproductive Health, 2005.

<p>Important candidate genes to human bone phenotypes are those involved in the regulation of hormonal action, such as the vitamin D receptor (VDR) and the estrogen receptor-α (ERα) genes and their cofactors. RIZ1 is a specific ERα cofactor proved to strongly enhance the function of the ERα. </p><p>The main focus of this thesis has been to study genetic variants in the VDR and RIZ genes and their associations to human bone phenotypes using candidate gene and functional approaches. Specifically, polymorphisms in the VDR 3’ untranslated region (UTR) and a deletion/insertion polymorphism of a proline in the RIZ gene were investigated.</p><p>The candidate gene approach was applied to large-scale population-based cohorts of pre-and post-menopausal women from Sweden and of elderly men from Sweden and Hong Kong. VDR 3’ UTR polymorphisms were associated with peak bone mass and body composition in young women. Further analysis of common VDR 3’ UTR haplotypes confirmed the association with BMD and risk of fractures in elderly men from Sweden and Hong Kong. The VDR polymorphisms were investigated for cis-acting effects, affecting allelic expression in the normal chromosomal context of human bone cells. The VDR allelic transcripts in the bone samples were unequally expressed, suggesting presence of regulatory variants in the 3’ UTR. </p><p>The polymorphism in the RIZ gene was strongly associated to BMD in pre- and postmenopausal women and in elderly men. The functional analyses included reporter constructs containing the RIZ polymorphic variants transfected in a cell line and its abilities in coactivating the ERα were examined. The variants were functionally different in coactivating the ERα-receptor complex. </p><p>To summarize, the results of this thesis show novel evidence for functional relevant polymorphisms in candidate genes to human bone phenotypes. These polymorphisms may contribute to the variation seen in BMD and risk of fractures in the population.</p>

Important candidate genes to human bone phenotypes are those involved in the regulation of hormonal action, such as the vitamin D receptor (VDR) and the estrogen receptor-α (ERα) genes and their cofactors. RIZ1 is a specific ERα cofactor proved to strongly enhance the function of the ERα. The main focus of this thesis has been to study genetic variants in the VDR and RIZ genes and their associations to human bone phenotypes using candidate gene and functional approaches. Specifically, polymorphisms in the VDR 3’ untranslated region (UTR) and a deletion/insertion polymorphism of a proline in the RIZ gene were investigated. The candidate gene approach was applied to large-scale population-based cohorts of pre-and post-menopausal women from Sweden and of elderly men from Sweden and Hong Kong. VDR 3’ UTR polymorphisms were associated with peak bone mass and body composition in young women. Further analysis of common VDR 3’ UTR haplotypes confirmed the association with BMD and risk of fractures in elderly men from Sweden and Hong Kong. The VDR polymorphisms were investigated for cis-acting effects, affecting allelic expression in the normal chromosomal context of human bone cells. The VDR allelic transcripts in the bone samples were unequally expressed, suggesting presence of regulatory variants in the 3’ UTR. The polymorphism in the RIZ gene was strongly associated to BMD in pre- and postmenopausal women and in elderly men. The functional analyses included reporter constructs containing the RIZ polymorphic variants transfected in a cell line and its abilities in coactivating the ERα were examined. The variants were functionally different in coactivating the ERα-receptor complex. To summarize, the results of this thesis show novel evidence for functional relevant polymorphisms in candidate genes to human bone phenotypes. These polymorphisms may contribute to the variation seen in BMD and risk of fractures in the population.

The vitamin D metabolite 1,25(OH)2D3 has long been known to inhibit growth of prostate cancer cells and this mainly through a VDR-mediated pathway controlling target gene expression, resulting in cell cycle arrest, apoptosis and differentiation. Another major way in which 1,25(OH)2D3 inhibits cell growth in prostate cancer is via membrane-initiated steroid signalling, which triggers activation of signal cascades upon steroid binding to a receptor complex, leading to induction of genes regulating cell growth, proliferation and apoptosis. The main prostate cancer inhibiting membrane-initiated route is the TGFβ signalling pathway, elicited by the protein TGFβ. In this experiment the activating effects of 1,25(OH)2D3 on TGFβ in prostate cancer cells, as well as two other important proteins downstream in this cascade, Smad2 and 3, were investigated. PC-3 cells were incubated for 3, 5, 10, 30 and 60 minutes as well as 38 hours both together with 1,25(OH)2D3 of the concentrations 10-10 and 10-7 M and without. As the downstream cascade protein JNK is a known activator of Smad2/3, this procedure was also repeated with a JNK inhibitor. An ELISA assay scanning for activated TGFβ was then performed on supernatants from the cells treated without JNK inhibitor. In addition, a Western Blot scanning for activated Smad2 and 3 was performed on supernatants from all groups of treatment. The analysis of the result values showed that 10-10 M 1,25(OH)2D3 significantly lowered the content of active TGFβ in PC-3 cells within 3 and 5 minutes. Unfortunately the Western Blot was unsuccessful and needs therefore be repeated.

The vitamin D metabolite 1,25(OH)2D3 has long been known to inhibit growth of prostate cancer cells and this has been attributed to a VDR-mediated pathway controlling target gene expression, resulting in cell cycle arrest, apoptosis and differentiation. New research has shown that another vitamin D metabolite, 24,25(OH)2D3, inhibits proliferation of prostate cancer cells as well, more specifically, cells of the line LNCaP. It is not clear exactly how 24,25(OH)2D3 exerts this cancer growth inhibition but it has been shown that it is to some extent regulated via G protein coupled signalling pathways. Catalase is a haem-containing redox enzyme found in the majority of animal cells, plant cells and aerobic microorganisms. This enzyme is very important because it prevents excessive accumulation of the strongly oxidizing agent H2O2 which otherwise can do damage to the cells. Because of this preventive effect of catalase, important cellular processes which generate H2O2 as by-product can proceed safely. Biochemical analysis of catalase has shown that it binds endogenously to 24,25(OH)2D3. The fact that 24,25(OH)2D3 has anti-proliferative effects on prostate cancer cells combined with the fact that it binds to catalase generates the hypothesis that this binding interferes with the essential task of catalase to keep the cell free from accumulation of destructive H2O2, and by means of this interference induces apoptosis. Finding out about the cancer growth inhibiting mechanism behind each vitamin D metabolite is important and may be a lead in the search for a new, better treatment of prostate cancer. The specific aim of this project was to study if and in what way 24,25(OH)2D3 affects the enzymatic activity of catalase in LNCaP cells and to do this with dose and time responses in focus. In this experiment LNCaP cells were incubated for 48 hours together with 24,25(OH)2D3 in five different concentrations, then a catalase assay was performed on the cells including fluorescence-mediated measuring of catalase activity in both treated and untreated cells. The analysis of the result values showed that regardless of dose or time, 24,25(OH)2D3 has no statistically significant effect on catalase activity in cells of the line LNCaP.

The vitamin D metabolite 1,25(OH)2D3 has long been known to inhibit growth of prostate cancer cells and this has been attributed to a VDR-mediated pathway controlling target gene expression, resulting in cell cycle arrest, apoptosis and differentiation. New research has shown that another vitamin D metabolite, 24,25(OH)2D3, inhibits proliferation of prostate cancer cells as well, more specifically, cells of the line LNCaP. It is not clear exactly how 24,25(OH)2D3 exerts this cancer growth inhibition but it has been shown that it is to some extent regulated via G protein coupled signalling pathways. Catalase is a haem-containing redox enzyme found in the majority of animal cells, plant cells and aerobic microorganisms. This enzyme is very important because it prevents excessive accumulation of the strongly oxidizing agent H2O2 which otherwise can do damage to the cells. Because of this preventive effect of catalase, important cellular processes which generate H2O2 as by-product can proceed safely. Biochemical analysis of catalase has shown that it binds endogenously to 24,25(OH)2D3. The fact that 24,25(OH)2D3 has anti-proliferative effects on prostate cancer cells combined with the fact that it binds to catalase generates the hypothesis that this binding interferes with the essential task of catalase to keep the cell free from accumulation of destructive H2O2, and by means of this interference induces apoptosis. Finding out about the cancer growth inhibiting mechanism behind each vitamin D metabolite is important and may be a lead in the search for a new, better treatment of prostate cancer. This is a follow-up to an earlier study, and the specific aim of this project was to find out if and in what way 24,25(OH)2D3 affects the enzymatic activity of catalase in LNCaP cells during long-term treatment (up to 48 hours). In this experiment LNCaP cells were incubated for 48 hours together with 24,25(OH)2D3 of the concentration 10-8 M, then a catalase assay was performed on the cells including fluorescence-mediated measuring of catalase activity in both treated and untreated cells. The analysis of the result values showed that despite of the rather high dose used, 24,25(OH)2D3 has no statistically significant effect on catalase activity in cells of the line LNCaP, regardless of time.

Acute demyelination in children may be a monophasic illness or the sentinel attack of multiple sclerosis (MS) – a chronic inflammatory neurodegenerative demyelinating disease. MS risk is largely determined during childhood and vitamin D may protect against MS. The primary objective of this thesis was to evaluate vitamin D status in children presenting with acute demyelinating syndromes (ADS) as a potential contributor to MS outcome. The LIAISON “25 OH Vitamin D TOTAL” assay was validated to assess the biomarker of vitamin D status – serum 25-hydroxyvitamin D (25(OH)D) concentrations. Consecutive patients (<16 y) were enrolled at presentation with ADS and prospectively evaluated at 23 Canadian centres. MS was defined by a second clinical demyelinating event or by MRI evidence of new lesions over time. Cox proportional hazards regression models assessed risk of MS outcome as a function of serum 25(OH)D tertiles, accounting for factors associated with either MS risk or vitamin D status – age, sex, season, and HLA-DRB1*15 status. Of 211 children with 25(OH)D measured in sera obtained a median of 9 days from onset (interquartile range, 5 – 17 d; maximum 36 days), 20% (n = 41) were diagnosed with MS after 3.7 mos. (3.1 – 7.3 mos.). Risk of MS was lower in children with 25(OH)D levels in the highest tertile (≥ 74 nmol/L) at ADS versus those in the lowest tertile (<50 nmol/L) (HR 0.41; 95% CI 0.18 to 0.97, adjusted model). Children with higher circulating 25(OH)D concentrations at ADS have a lower risk of MS. Further evidence for a role of vitamin D insufficiency during childhood and adolescence contributing to MS risk comes from three MS patients with suboptimally managed pseudo-vitamin D deficiency rickets. Finally, a sun exposure questionnaire was validated in the latter part of this thesis for use in future research into determinants of vitamin D status and their association with risk of MS.

Acute demyelination in children may be a monophasic illness or the sentinel attack of multiple sclerosis (MS) – a chronic inflammatory neurodegenerative demyelinating disease. MS risk is largely determined during childhood and vitamin D may protect against MS. The primary objective of this thesis was to evaluate vitamin D status in children presenting with acute demyelinating syndromes (ADS) as a potential contributor to MS outcome. The LIAISON “25 OH Vitamin D TOTAL” assay was validated to assess the biomarker of vitamin D status – serum 25-hydroxyvitamin D (25(OH)D) concentrations. Consecutive patients (<16 y) were enrolled at presentation with ADS and prospectively evaluated at 23 Canadian centres. MS was defined by a second clinical demyelinating event or by MRI evidence of new lesions over time. Cox proportional hazards regression models assessed risk of MS outcome as a function of serum 25(OH)D tertiles, accounting for factors associated with either MS risk or vitamin D status – age, sex, season, and HLA-DRB1*15 status. Of 211 children with 25(OH)D measured in sera obtained a median of 9 days from onset (interquartile range, 5 – 17 d; maximum 36 days), 20% (n = 41) were diagnosed with MS after 3.7 mos. (3.1 – 7.3 mos.). Risk of MS was lower in children with 25(OH)D levels in the highest tertile (≥ 74 nmol/L) at ADS versus those in the lowest tertile (<50 nmol/L) (HR 0.41; 95% CI 0.18 to 0.97, adjusted model). Children with higher circulating 25(OH)D concentrations at ADS have a lower risk of MS. Further evidence for a role of vitamin D insufficiency during childhood and adolescence contributing to MS risk comes from three MS patients with suboptimally managed pseudo-vitamin D deficiency rickets. Finally, a sun exposure questionnaire was validated in the latter part of this thesis for use in future research into determinants of vitamin D status and their association with risk of MS.

La modulació inadequada o el manteniment de forma crònica de la resposta immune poden provocar efectes adversos a sistemes i òrgans i donar lloc a la manifestació de patologies. En aquest context, els mecanismes de regulació de la resposta immune són un element clau per mantenir un estat òptim de salut i un envelliment saludable. La capacitat d'organitzar una resposta immune contra agents patògens o cèl·lules tumorals està en part determinada pel fons genètic de cada individu. Els estudis d'associació genètica han resultat d'utilitat per identificar variants de gens de resposta immune implicades en patologies que van des del càncer o les malalties cardiovasculars a infeccions com la tuberculosi o el VIH-­‐1. En la present tesi s'ha estudiat la variabilitat de gens de resposta immune i el seu paper en dos models diferents: la infecció per VIH-­‐1 i el procés d'envelliment natural. En el primer model s'ha estudiat la variabilitat del gen BST-­‐2, factor de restricció en la infecció per VIH-­‐1, i dels gens CYP27B1, GC i VDR, implicats en la síntesi, transport i acció genòmica de la vitamina D, hormona implicada en la modulació de la resposta immune. Així mateix, al segon model s'ha avaluat l'efecte de la variabilitat del gen VDR i dels gens RANTES i CCR5, implicats en la mediació de la resposta inflamatòria. En el model d'infecció per VIH-­‐1 s'han identificat 2 variants del gen BST-­‐2 associades amb progressió, una captura la variabilitat de la regió genòmica i l’altra amb potencial efecte funcional. En l'estudi de la relació de variants dels gens VDR, CYP27B1 i GC amb el ritme de progressió de la infecció s'han confirmat i ampliat el nombre de marcadors del gen VDR que mostren associació amb progressió. Les combinacions haplotípiques del gen VDR que s'associen amb progressió són aquelles que optimitzen la resposta a la vitamina D. Aquests resultats poden interpretar-­‐se en funció del paper dual de la vitamina D en la modulació de la resposta immune. L'associació amb progressió de les variants identificades és més significativa en els pacients reclutats en el període pre-­‐ TARGA (anterior a 1997). En el model d'envelliment natural, variants del gen VDR mostren associació amb envelliment saludable en homes. Les variants associades són aquelles que confereixen una capacitat de resposta intermèdia a la vitamina D. Això emfatitza el paper de la vitamina D en envelliment i posa de manifest la importància del fons genètic a l’hora d’establir els nivells òptims de vitamina D per a un envelliment saludable. En relació als polimorfismes dels gens CCR5 i RANTES no s'ha trobat associació significativa pel locus CCR5, encara que els resultats mostren una major prevalença de la variant no funcional, i per tant pitjor mediadora de la resposta inflamatòria, en individus longeus. Quant a les variants del gen RANTES, els resultats indiquen una associació específica de sexe que suggereix l'existència d'un determinant genètic de RANTES que predisposa a un fenotip proinflamatori en homes i a un fenotip antiinflamatori en dones / La modulación inadecuada o el mantenimiento de forma crónica de la respuesta inmune puede provocar efectos adversos en sistemas y órganos y dar lugar a la manifestación de patologías. Por ello, los mecanismos de regulación de la respuesta inmune son un elemento clave para el mantenimiento de un estado de salud óptimo y un envejecimiento saludable. La capacidad de organizar una respuesta inmune contra agentes patógenos o células tumorales está en parte determinada por la fondo genético de cada individuo. Los estudios de asociación genética han resultado de utilidad para identificar variantes de genes de respuesta inmune implicadas en patologías que van desde el cáncer o las enfermedades cardiovasculares a infecciones como la tuberculosis o el VIH-­‐1. En la presente tesis se ha estudiado la variabilidad de genes de respuesta inmune y su papel en dos modelos distintos: la infección por VIH-­‐1 y el proceso de envejecimiento natural. En el primer modelo se ha estudiado la variabilidad del gen BST-­‐2, factor de restricción en la infección por VIH-­‐1, y de los genes CYP27B1, GC y VDR, implicados en la síntesis, transporte y acción genómica de la vitamina D, hormona implicada en la modulación de la respuesta inmune. Asimismo, en el segundo modelo, se ha evaluado el efecto de la variabilidad del gen VDR y de los genes RANTES y CCR5, implicados en la mediación de la respuesta inflamatoria. En el modelo de infección por VIH-­‐1, se han identificado 2 variantes del gen BST-­‐ 2 asociadas con progresión, una que captura la variabilidad de la región genómica y otra con potencial efecto funcional. En el estudio de variantes de los genes VDR, CYP27B1 y GC con el ritmo de progresión de la infección se ha confirmado y ampliado el número de marcadores del gen VDR que muestran asociación con progresión. Las combinaciones haplotípicas del gen VDR que se asocian con progresión son aquellas que optimizan la respuesta a la vitamina D. Estos resultados pueden interpretarse en función del papel dual de la vitamina D en la modulación de la respuesta inmune. La asociación con progresión de las variantes identificadas incrementa su significación en los pacientes reclutados en el periodo pre-­‐TARGA (anterior a 1997). En el modelo de envejecimiento natural, variantes del gen VDR muestran asociación con envejecimiento saludable en hombres. Las variantes asociadas son aquellas que confieren una capacidad de respuesta intermedia a la vitamina D. Ello revela el papel de la vitamina D en envejecimiento y enfatiza la importancia del fondo genético al establecer los niveles óptimos de vitamina D para un envejecimiento saludable. En relación a los polimorfismos de los genes CCR5 y RANTES no se ha encontrado asociación significativa para el locus CCR5, aunque los resultados muestran una mayor prevalencia de la variante no funcional, y por lo tanto peor mediadora de la respuesta inflamatoria, en individuos longevos. En cuanto a las variantes del gen RANTES, los resultados indican una asociación específica de sexo que sugiere la existencia de un determinante genético de RANTES que predispone a un fenotipo proinflamatorio en los varones y a un fenotipo anti-­‐inflamatorio en las mujeres. / The improper balance or the maintenance of a chronic immune response can produce adverse effects on organs and systems and prone to diseases. Therefore, the regulatory mechanisms of the immune response are key factors to maintain an optimal health status and to follow a healthy aging. The capacity to produce an immune response against pathogens or tumour cells is partially determined by the genetic background of the individual. Genetic association studies have been useful to identify variants of immune response genes involved in diseases ranging from cancer or cardiovascular disease to infections such as tuberculosis or HIV-­‐1. In this thesis we have studied the variability of immune response genes and their role in two models: the HIV-­‐1 infection and the natural aging process. In the first model it has been studied the variability of BST-­‐2 gene, which is an HIV restriction factor, and CYP27B1, GC and VDR genes, that are involved in the synthesis, transport and genomic action of vitamin D, hormone that modulates the immune response. In the second model, we have also evaluated the effect of VDR gene variability as well as RANTES and CCR5 gene variants, both involved in mediating the inflammatory response. In the model of the HIV-­‐1 infection we have identified two variants of BST-­‐2 gene associated with progression, one that captures the variability of the genomic region and the other with potential functional effect. In the study of VDR, CYP27B1 and GC gene variants related to progression rates we have confirmed and extended the number of VDR gene markers showing association with progression. The VDR gene haplotype combinations that are associated with progression are those that optimize the response to vitamin D. These results should be interpreted as a con to the dual role of vitamin D in the modulation of the immune response. The association with progression of the identified variants is significantly increased in patients enrolled in the pre-­‐HAART (before 1997). In the model of aging, VDR gene variants were most associated with healthy aging in men. The associated variants are those that confer an intermediate responsiveness to vitamin D. This reveals the role of vitamin D in aging and emphasizes the role of genetic background in determining optimal levels of vitamin D for healthy aging. In relation to polymorphisms of CCR5 and RANTES genes we do not found significant association for the CCR5 locus, although the results show a higher prevalence of non-­‐functional variant, and thus a poorer mediator of the inflammatory response, in long-­‐lived individuals. In relation to RANTES gene variants, the results indicate a sex-­‐specific association suggesting the existence of a genetic determinant of RANTES that predisposes to a proinflammatory phenotype in males and an anti-­‐inflammatory phenotype in females.