Association of selected gene polymorphisms regulating vascular endothelial growth factor with bone mineral density and high blood pressure

Visok krvni tlak in osteoporoza sta kronični bolezni, ki do pojava zapletov večinoma potekata brez simptomov. Za obe bolezni je poleg številnih okoljskih dejavnikov tveganja značilno prisoten tudi genetski vpliv. Žilni endotelijski rastni dejavnik (VEGF) je signalna beljakovina iz družine rastnih faktorjev cistinskih vozlov, ki ima pomembno vlogo pri tvorbi novih krvnih žil v obdobju razvoja, v fizioloških procesih pri odraslih in v patologiji določenih bolezni. Vpliv VEGF na mineralno kostno gostoto (MKG) in razvoj osteoporoze še ni natančno opredeljen. Podatki študij namigujejo na to, da fiziološke koncentracije VEGF vzdržujejo homeostazo kostne prenove, medtem ko premajhne ali prevelike koncentracije VEGF vodijo k povečanju razgradnje kosti in posledično nastanku osteoporoze. Povezavo med VEGF in visokim krvnim tlakom lahko opazimo pri zdravljenju z zaviralci VEGF. Pogost neželeni učinek zdravil, ki zavirajo VEGF in njegove signalne poti, je povišan krvni tlak, ki se pojavi pri vsaj četrtini zdravljenih bolnikov. Naš cilj je bil ugotoviti vpliv polimorfizmov rs4416670, rs6921438, rs6993770 in rs10738760 na MKG in visok krvni tlak. Z asociacijskimi študijami na celotnem genomu so dokazali, da so izbrani polimorfizmi odgovorni za približno 50 % variabilnosti serumske koncentracije VEGF. Polimorfizma rs4416670 in rs6921438 se nahajata na kromosomu 6p21.1 v bližini gena za VEGF. Polimorfizem rs6993770 se nahaja na kromosomu 8q23.1 v genu ZFPM2, medtem ko se polimorfizem rs10738760 nahaja na kromosomu 9p24.2 v bližini genov VLDLR in KCNV2. Tristopetnajstim pomenopavznim preiskovankam smo iz izoliranih DNA vzorcev s pomočjo verižne reakcije s polimerazo in uporabo hidrolizirajočih sond določili genotipe za izbrane polimorfizme. S statistično analizo smo ugotavljali vpliv izbranih polimorfizmov na MKG in osteoporozo, ter povezavo med izbranimi polimorfizmi in visokim krvnim tlakom pri pomenopavznih preiskovankah. Pri polimorfizmu rs4416670 smo ugotovili statistično značilni (p = 0,04) višji delež genotipske podskupine TT (nemutirani homozigoti) v skupini preiskovank z osteoporozo v primerjavi z osteopeničnimi in zdravimi preiskovankami. Prav tako je genotipska podskupina TT v primerjavi z združenima genotipskima podskupinama CT in CC (mutirani homozigoti) pri polimorfizmu rs4416670 negativno vplivala na MKG trohantra (p = 0,035), intertrohantra (p = 0,025) in kolka (p = 0,022) pri vseh pomenopavznih preiskovankah. Pri polimorfizmu rs6921438 so imele pomenopavzne preiskovanke z genotipsko podskupino AA (mutirani homozigoti) značilno višjo MKG stegnenice (p = 0,031) in intertrohantra (p = 0,029) v primerjavi z genotipsko podskupino GG (nemutirani homozigoti). V skupini zdravih preiskovank smo za ta polimorfizem prav tako pri genotipski podskupini GG ugotovili značilno nižji MKG na predelu trohantra (p = 0,019), intertrohantra (p = 0,028) in kolka (p = 0,017) v primerjavi z združenima podskupinama AG in AA. Na osnovi dobljenih rezultatov sklepamo, da polimorfizma rs4416670 in rs69214380 pri pomenopavznih preiskovankah vplivata na MKG in posledično na tveganje za osteoporozo. Polimorfizma rs6993770 in rs10738760 na MKG oziroma osteoporozo ne vplivata. Značilnega vpliva izbranih polimorfizmov na visok krvni tlak nismo ugotovili.Hypertension and osteoporosis are chronic diseases that, until complications occur, are mostly asymptomatic. In addition to several environmental risk factors, both diseases are also characterized by genetic influences. Vascular endothelial growth factor (VEGF) is a signaling protein from the cystine knot growth factor family, which also includes VEGF-B, VEGF-C, VEGF-D, and placental growth factor. VEGF plays an important role in the formation of new blood vessels during development, physiological processes in adults, and pathology of certain diseases. The effect of VEGF on bone mineral density (BMD) and the development of osteoporosis has not yet been precisely defined. Research data suggest that physiological VEGF circulating levels help to maintain bone regeneration homeostasis, whereas low or high VEGF levels lead to increased bone degradation and osteoporosis. An association between VEGF and high blood pressure can be observed in anti-VEGF therapy. A common side effect of drugs that inhibit VEGF and its signaling pathways is high blood pressure, which occurs in at least a quarter of treated patients. We aimed to determine the influence of rs4416670, rs6921438, rs6993770, and rs10738760 polymorphisms on BMD and high blood pressure. Genome-wide association studies have shown that selected polymorphisms are responsible for approximately 50 % of the variability in serum circulating VEGF levels. The polymorphisms rs4416670 and rs6921438 are located on chromosome 6p21.1 near the VEGF gene. The rs6993770 polymorphism is located on chromosome 8q23.1 in the ZFPM2 gene, while the rs10738760 polymorphism is located on chromosome 9p24.2 near the VLDLR and KCNV2 genes. In 315 postmenopausal women, the genotypes of selected polymorphisms were determined from isolated DNA samples using real-time polymerase chain reaction (qPCR). The influence of selected polymorphisms on BMD and osteoporosis was determined by statistical analysis, as well as the connection between selected polymorphisms and high blood pressure in postmenopausal women. TT (wild-type homozygotes) of rs4416670 polymorphism were found to be more frequent (p = 0.04) in the group of women with osteoporosis compared to the osteopenia group and group of healthy postmenopausal women. Compared to the combined genotypic subgroups CT and CC (mutated homozygotes), genotypic subgroup TT of rs4416670 polymorphism also negatively affected BMD of the trochanter (p = 0.035), intertrochanter (p = 0.025) and hip (p = 0.022) in all postmenopausal women. Genotype subgroup AA (mutated homozygotes) of rs6921438 polymorphism had significantly higher BMD of the femoral neck (p = 0.031) and intertrochanter (p = 0.029) in comparison to genotype GG (wild type). For this polymorphism we also found a significantly lower BMD of the trochanter (p = 0.019), intertrochanter (p = 0.028) and hip (p = 0.017) in the GG genotype group of healthy women compared to combined subgroups AG and AA. Based on the obtained results, we conclude that the polymorphisms rs4416670 and rs69214380 in postmenopausal subjects affect BMD and consequently the risk of osteoporosis. Polymorphisms rs6993770 and rs10738760 do not affect BMD or osteoporosis. There was no effect of selected polymorphisms on high blood pressure