Pharmacogenetics of osteoporosis: a pathway analysis of the genetic influence on the effects of antiresorptive drugs

Osteoporosis is a skeletal disorder defined by a decreased bone mineral density (BMD) and an increased susceptibility to fractures. Bisphosphonates and selective oestrogen receptor modulators (SERM) are among the most widely used drugs. They inhibit bone resorption by targeting the mevalonate and oestrogen pathways, respectively. The aim of this study was to determine if common variants of genes in those pathways influence drug responses. We studied 192 women treated with oral aminobisphosphonates and 51 with SERMs. Genotypes at 154 SNPs of the mevalonate pathway and 806 in the oestrogen pathway were analyzed. Several SNPs located in genes FDPS and FNTA were associated with the bisphosphonate-induced changes in hip bone mineral density (BMD), whereas polymorphisms of the PDSS1, CYP19A1, CYP1A1, and CYP1A2 genes were associated with SERM-induced changes in spine BMD. After multivariate analyses, genotypes combining genes FDPS and FNTA showed a stronger association with bisphosphonate response (r = 0.34; p = 0.00009), whereas the combination of CYP19A1 and PDSS1 genotypes was associated with the response to SERMs (r = 0.62, p = 0.0003). These results suggest that genotyping genes in these pathways may help predict the response to antiresorptive drugs and hence make personalized therapeutic choices.Funding: Supported by grants from Instituto de Salud Carlos III (PI18/00762; PI21/00532) that could be cofunded by European Union FEDER funds. Genotyping service was carried out at CEGEN-PRB3-ISCIII; it is supported by grant PT17/0019, of the PE I+D+i 2013–2016, funded by ISCIII and ERDF. Acknowledgments: Alvaro del Real received support by the postdoctoral grant Augusto Gonzalez de Linares of the University of Cantabria. We thank the skilful technical assistance of Carolina Sañudo and Alicia Martin-Rebollo

Bone turnover markers in Spanish postmenopausal women: the Camargo cohort study

BACKGROUND. This cross-sectional study was performed to determine the reference ranges for two bone turnover markers -aminoterminal propeptide of type I collagen (P1NP) and C-terminal telopeptide of type I collagen ( - CrossLaps, -CTX)- in normal postmenopausal Spanish women as determined in serum by automated methods. METHODS. A community-based population of 1080 healthy postmenopausal women was evaluated. Data regarding risk factors for osteoporosis and fractures were collected by means of a structured questionnaire. Fasting serum levels of P1NP, -CTX, 25-Hydroxivitamin D (25OHD), and intact parathyroid hormone (iPTH) were measured on the Elecsys 2010 automated analyzer (Roche). BMD at lumbar spine, femoral neck and total hip was determined by DXA. RESULTS. The mean age of subjects was 63±9. Logarithmic transformation of both markers was performed to allow for normal distributions. Mid-95% ranges for P1NP and -CTX were 19-100 ng/ml and 0.112-1.018 ng/ml, respectively. Mean values of P1NP (47.7±19.9 ng/ml) were similar to those previously determined by the manufacturer of the assays, whereas -CTX mean values (0.387± 0.197 ng/ml) were lower. Both markers were higher among osteoporotic women. CONCLUSIONS. Values obtained from this well-characterized population study provide reference ranges for serum automated P1NP and -CTX in normal Spanish postmenopausal women

Identification of an aromatase haplotype that is associated with gene expression and postmenopausal osteoporosis

Context: Osteoporosis has a significant genetic component. The aromatase-dependent conversion of androgenic precursors is the main source of estrogens in postmenopausal women. Objective: The objective of the investigation was to study the relationship of a set of single nucleotide polymorphisms (SNPs) of the aromatase gene with osteoporosis and determine their functional influence on gene transcription. Design, Participants, and Methods: This was a case-control study including 135 women with vertebral fractures due to postmenopausal osteoporosis and 312 controls. Alleles at four SNPs situated between exons I.2 and 3 were determined by Taqman assays. Total aromatase RNA and differential allelic-specific expression were studied by RT-real time PCR in adipose tissue samples taken from 50 individuals. Results: The SNPs studied were in strong linkage disequilibrium. A common haplotype, present in about half of the population, was identified as being associated with an increased risk of fractures (odds ratio 1.8, 95% confidence interval 1.2–2.8, P = 0.006). There was evidence of differential allelic expression. In heterozygous individuals, transcripts bearing T alleles at rs700518 SNP (which were included in the risk haplotype) were less abundant than those with the alternative C alleles (P < 0.001). Total aromatase expression was four times lower in fat samples from individuals who were homozygotes for the unfavorable alleles than in the opposite homozygotes (P = 0.007). Conclusions: A common haplotype of aromatase associated with gene expression is also associated with the risk of osteoporotic vertebral fractures in postmenopausal women. These data are in line with the hypothesis that the aromatase-dependent synthesis of estrogens plays an important role in bone homeostasis in postmenopausal women

Non-synonymous WNT16 polymorphisms alleles are associated with different osteoarthritis phenotypes

Hereditary factors have a strong influence on osteoarthritis (OA). The Wnt pathway is involved in bone and cartilage homeostasis. Hence, we hypothesized that allelic variations of WNT16 could influence the OA phenotype. We studied 509 Caucasian patients undergoing joint replacement due to severe primary OA. Radiographs were used to classify the OA as atrophic or hypertrophic. Two nonsynonymous polymorphisms of WNT16 (rs2707466 and rs2908004) were analyzed. The association between the genotypes and the OA phenotype was analyzed by logistic regression and adjusted for age and body mass index. A genotype-phenotype association was found in the sex-stratified analysis. Thus, there was a significant difference in the genotypic frequencies of rs2707466 between hypertrophic and atrophic hip OA in males (p = 0.003), with overrepresentation of G alleles in the hypertrophic phenotype (OR 2.08; CI 1.28-3.38). An association in the same direction was observed between these alleles and the type of knee OA, with G alleles being more common in the hypertrophic than in atrophic knee phenotypes (p = 0.008; OR 1.956, CI 1.19-3.19). Similar associations were found for the rs2908004 SNP, but it only reached statistical significance for knee OA (p = 0.017; OR 0.92, CI 0.86-0.989). This is the first study attempting to explore the association of genetic variants with the OA phenotype. These data suggest the need to consider the OA phenotype in future genetic association studies of OA

Relationship of sclerostin and secreted frizzled protein polymorphisms with bone mineral density: an association study with replication in postmenopausal women

Objectives.- Secreted frizzled-related protein and sclerostin, encoded by FRZB and SOST genes, respectively, are extracellular Wnt inhibitors that tend to decrease bone formation. The purpose of this study was to explore the association of sets of polymorphisms capturing common variations of these genes with bone mineral density (BMD). Methods.- Twelve polymorphic loci of the FRZB gene and 7 of the SOST gene were genotyped in postmenopausal women from two Spanish regions (Cantabria, n=1043, and Valencia, n=342). The polymorphisms included tagging SNPs and SNPs with possible functional consequences assessed in silico. Results.-The rs4666865 polymorphism of the FRZB gene was associated with spine BMD in the Cantabria cohort in the single-locus (p=0.008) and the haplotypic analysis. However, the results were not replicated in the Valencia cohort. Several polymorphisms at the 5´region of the SOST gene, and particularly rs851056, were associated with BMD in women from both cohorts (p=0.002 in Cantabria and 0.005 in Valencia). When the results of both cohorts were combined, the mean BMD difference across rs851056 genotypes was 47 mg/cm2 or 0.31 standard deviations (p<0.001). No differences in FRZB and SOST expression was detected across genotypes. Conclusions.- Polymorphisms in the 5’ region of SOST gene are associated with BMD in postmenopausal women, and consequently contribute to explain in part the hereditary influence on bone mass

Abnormal bone turnover in individuals with low serum alkaline phosphatase

The clinical spectrum of hypophosphatasia (HPP) is broad and variable within families. Along severe infantile forms, adult forms with mild manifestations may be incidentally discovered by the presence of low alkaline phosphatase (ALP) activity in serum. However, it is still unclear whether individuals with persistently low levels of ALP, in the absence of overt manifestations of HPP, have subclinical abnormalities of bone remodeling or bone mass. The aim of this study was to obtain a better understanding of the skeletal phenotype of adults with low ALP by analyzing bone mineral density (BMD), bone microarchitecture (trabecular bone score, TBS), and bone turnover markers (P1NP and ß-crosslaps). We studied 42 individuals with persistently low serum ALP. They showed lower levels of P1NP (31.4?±?13.7 versus 48.9?±?24.4 ng/ml; p?=?0.0002) and ß-crosslaps (0.21?±?0.17 versus 0.34?±?0.22 ng/ml, p?=?0.0015) than individuals in the control group. There were no significant differences in BMD, bone mineral content, or TBS. These data suggest that individuals with hypophosphatasemia have an overall reduction of bone turnover, even in the absence of overt manifestations of HPP or low BMD. We evaluated bone mineral density (BMD), bone microarchitecture, and bone turnover markers in patients with low serum levels of alkaline phosphatase. Our results show that these patients have low bone remodeling even in the absence of BMD abnormalities, thus supporting the recommendation of avoiding antiresorptives such as bisphosphonates in these subjects

Cribado de riesgo poligénico de fracturas óseas en mujeres de España con osteoporosis

Dado que la osteoporosis tiene un importante componente hereditario, el conocimiento de las variantes genéticas implicadas puede permitir la identificación precoz de los sujetos en riesgo y la instauración de medidas preventivas no farmacológicas. Por otro lado, puede ayudar a seleccionar más eficientemente los grupos de población en los que aplicar medios diagnósticos y terapéuticos más sofisticados. La osteoporosis tiene un carácter poligénico, por lo que se están intentando elaborar puntuaciones de riesgo basadas en el análisis de múltiples genes ("polygenic risk scores", PRS). En esta línea, recientemente se ha propuesto un PRS generado a partir de los datos genotípicos y de ultrasonografía de calcáneo como ayuda en la predicción de fracturas (Forgetta V, PLoS Med. 2020 ;17(7): e1003152). El objetivo de este estudio fue analizar la capacidad de ese índice para predecir osteoporosis en la población española. Estudiamos 1.747 mujeres, de las cuales 307 (65±9 años) fueron previamente diagnosticadas con osteoporosis y 1.440 (49±17 años) eran controles de población general. En todas ellas se hizo un análisis genómico con el Spanish Biobank Array. Tras solapar las variantes genotipadas con las del estudio referido, analizamos finalmente un total de 10.319 marcadores. Las puntuaciones del PRS fueron significativamente menores en el grupo de osteoporosis que en el grupo control (-2,40 versus -1,75; p=5,68x10-12). Esas diferencias persistían después de incluir la edad como covariable (p=2,78x10-11). Con el modelo ajustado por la edad, el PRS mostró un poder predictivo bastante alto, con un área bajo la curva de 0,875 (95% IC 0,775-0,925). En comparación con las mujeres de los otros cuartiles, aquellas con puntuación PRS en el primer cuartil tenían un riesgo de osteoporosis significativamente mayor (OR=2,1; 95% IC 1,6-2,7; p=9,01x10-8). Sin embargo, dentro del grupo de osteoporosis, no hemos encontrado asociación del PRS con variables como la DMO basal de región lumbar, cadera total o cuello de fémur. En resumen, la aplicación de este PRS muestra diferencias significativas entre la población general española y las pacientes con osteoporosis, lo que sugiere su utilidad dentro de estrategias de identificación de sujetos en riesgo basado en criterios clínicos-genéticos

Hyperbaric Oxygen Therapy Does Not Have a Negative Impact on Bone Signaling Pathways in Humans

Introduction: Oxygen is emerging as an important factor in the local regulation of bone remodeling. Some preclinical data suggest that hyperoxia may have deleterious effects on bone cells. However, its clinical relevance is unclear. Hence, we studied the effect of hyperbaric oxygen therapy (HBOT) on serum biomarkers reflecting the status of the Wnt and receptor activator of NF-?B ligand (RANKL) pathways, two core pathways for bone homeostasis. Materials and methods: This was a prospective study of 20 patients undergoing HBOT (mean age 58 yrs., range 35?82 yrs.) because of complications of radiotherapy or chronic anal fissure. Patients were subjected to HBOT (100% oxygen; 2.4 atmospheres absolute for 90 min). The average number of HBOT sessions was 20 ± 5 (range 8?31). Serum hypoxia-inducible factor 1-? (HIF1-?), osteoprotegerin (OPG), RANKL, and the Wnt inhibitors sclerostin and dickkopf-1 (DKK1) were measured at baseline and after HBOT by using specific immunoassays. Results: HIF-1? in eight patients with measurable serum levels increased from 0.084 (0.098) ng/mL at baseline to 0.146 (0.130) ng/mL after HBOT (p = 0.028). However, HBOT did not induce any significant changes in the serum levels of OPG, RANKL, sclerostin or DKK1. This was independent of the patients? diagnosis, either neoplasia or benign. Conclusion: Despite the potential concerns about hyperoxia, we found no evidence that HBOT has any detrimental effect on bone homeostasis

Osterix and RUNX2 are Transcriptional Regulators of Sclerostin in Human Bone

Sclerostin, encoded by the SOST gene, works as an inhibitor of the Wnt pathway and therefore is an important regulator of bone homeostasis. Due to its potent action as an inhibitor of bone formation, blocking sclerostin activity is the purpose of recently developed antiosteoporotic treatments. Two bone-specific transcription factors, RUNX2 and OSX, have been shown to interact and co-ordinately regulate the expression of bone-specific genes. Although it has been recently shown that sclerostin is targeted by OSX in mice, there is currently no information of whether this is also the case in human cells. We have identified SP-protein family and AML1 consensus binding sequences at the human SOST promoter and have shown that OSX, together with RUNX2, binds to a specific region close to the transcription start site. Furthermore, we show that OSX and RUNX2 activate SOST expression in a co-ordinated manner in vitro and that SOST expression levels show a significant positive correlation with OSX/ RUNX2 expression levels in human bone. We also confirmed previous results showing an association of several SOST/RUNX2 polymorphisms with bone mineral density