Ekspresija glikoziltransferaza u leukocitima bolesnika s akutnim koronarnim sindromom [Expression of glycosyltransferases in leukocytes of patients with acute coronary syndrome]

Hadžibegović, Irzal (2013) Ekspresija glikoziltransferaza u leukocitima bolesnika s akutnim koronarnim sindromom [Expression of glycosyltransferases in leukocytes of patients with acute coronary syndrome]. PhD thesis, Sveučilište u Zagrebu.

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Abstract

Background and aim Acute coronary syndrome (ACS) is caused by destabilization and rupture of atherosclerotic plaque in the epicardial coronary artery. Mechanisms that affect cell signaling and production of factors promoting inflammation play the main role in that process. The majority of cellular communication takes place on the membrane whose surface is covered with oligosaccharide structures that are related to membrane proteins and lipids in the form of glycoproteins and glycolipids. Glycosylation is the only modification of proteins and lipid which can result in significant structural changes in the protein, and it is known to play an important role in the integration of different functions in higher organisms. The aim of this study was to determine the genetic expression of glycosyltransferases in patients with acute coronary syndrome and compare it with a control group of subjects that are proven to be coronary disease free. ----- Subjects and Methods The study included 52 patients with acute coronary syndrome and 32 subjects in the control group. Glycosyltransferases genetic expression was measured in patients with ACS on two occasions: in the acute phase within 24 hours of acute onset of chest pain, and in chronic phase (average of 8 days after onset of illness). After reverse transcription of RNA into DNA, real-time PCR was performed by SYBR Green protocol, and relative expression was measured. Reference genes used for relative expression measurement were β-actin and GAPDH. Statistical analysis was done using Mann-Whitney test, Wilxocon signed rank test, Spearman correlation test and chi square test. The level of significance was set to P<0.05. ----- Results There was a significantly lower relative expression of FUT 4 in patients with ACS in relation to both reference genes (P <0.001 for GAPDH and P <0.05 for beta-actin). This significant difference was also reflected in the second sampling in patients with ACS. There was no significant difference in FUT 7 expression between two groups in the acute phase. However, due to an almost 50% reduction in the expression of FUT 7 in patients with ACS in the second sampling, FUT7 expression in the second sampling was significantly lower when compared with the control group (P <0.001 for both reference genes). This effect was attributed to statin therapy, as significant downregulation of FUT 7 was found in subjects taking statins irrespective of the presence of acute coronary syndrome. ST6Gal1, GM3 synthase and ST6GalNac 4 were significantly downregulated in patients with ACS in both stages of disease (P <0.05, P <0.001 and P <0.05, respectively). There was a significantly lower expression ST6GalNac3 in ACS patients in the second sampling, which was also attributed to a significantly higher prevalence of statin therapy. ----- Conclusion There were significant differences in gene expression of glycosyltransferases responsible for the synthesis of lectins, syalizated Lewis X antigen, and ganglioside and for integrins syalization. All these structures play an important role in the promotion and control of inflammatory response, which is important in the development and progression of atherosclerosis. More basic and clinical studies on glycosyltransferases and glycosilation in the pathophysiology of the ACS are mandatory.

Abstract in Croatian

Uvod i cilj istraživanja Akutni koronarni sindrom bolest je koja nastaje destabilizacijom i rupturom aterosklerotskog plaka epikardijalne koronarne arterije u čemu glavnu ulogu igraju mehanizmi koji utječu na staničnu signalizaciju i proizvodnju čimbenika promocije upale. Glavnina stanične komunikacije zbiva se na membrani čija je površina pokrivena oligosaharidnim strukturama koje su vezane za membranske proteine i lipide u obliku glikoproteina i glikolipida. Glikozilacija je jedina modifikacija proteina i lipida koja može rezultirati značajnim strukturalnim promjenama proteina, a zna se da ima važnu ulogu u integraciji različitih funkcija u višim organizmima. Cilj istraživanja bio je odrediti gensku ekspresiju glikoziltransferaza u bolesnika s akutnim koronarnim sindromom i usporediti je s kontrolnom skupinom kod koje je isključena koronarna bolest. ----- Ispitanici i metode U istraživanje je uključeno 52 bolesnika s akutnim koronarnim sindromom i 32 ispitanika u kontrolnoj skupini. Bolesnicima su izmjerene genske ekspresije 8 fukoziltransferaza i 10 sijaliltransferaza u dva navrata: u akutnoj fazi unutar 24 sata od početka bolesti i u kroničnoj fazi prosječno 8 dana nakon početka bolesti. Nakon obrnutog prepisivanja RNA u DNA, PCR u stvarnom vremenu učinjena je prema SYBR Green protokolu, a za analizu relativne ekspresije kao referentni geni korišteni su β-actin i GAPDH. Za statističku analizu upotrijebljen je Mann-Whitney test, Wilxocon signed rank test, Spearmanov test korelacije i chi kvadrat test. Razina značajnosti P podešena je na 0.05. ----- Rezultati Nađena je značajno niža relativna ekspresija FUT 4 u bolesnika s akutnim koronarnim sindromom u odnosu na oba referentna gena (P<0,001 za GAPDH i P<0,05 za beta aktin). Ta značajna razlika očitovala se i u drugom uzorkovanju u bolesnika. Nije bilo značajnih razlika u ekspresiji FUT 7 između bolesnika u akutnoj fazi i kontrola. Međutim zbog gotovo 50% sniženja ekspresije FUT 7 u bolesnika u drugom uzorkovanju ta je ekspresija bila značajno niža u bolesnika u kroničnoj fazi u usporedbi s kontrolnom skupinom (P<0,001 za oba referentna gena). Taj učinak je pripisan terapiji statinima, s obzirom da je nađena značajno niža ekpresija FUT 7 u osoba koje su uzimale statine neovisno o prisutnosti akutnog koronarnog sindroma. Ekspresije ST6Gal1, GM3 sintaze i ST6GalNac 4 bile su značajno niže u bolesnika u oba vremena uzorkovanja i to za oba referentna gena (P<0,05, P<0,001 i P<0,05, tim redom). Nađena je značajno niža ekspresija ST6GalNac3 u bolesnika u drugom uzorkovanju, što je također pripisano značajno većoj zastupljenosti terapije statinima među bolesnicima. ----- Zaključak Nađene su značajne razlike u genskoj ekspresiji glikoziltransferaza zaduženih za sintezu lektina, sijaliziranog antigena Lewis X i gangliozida, te sijalizaciju integrina. Sve te strukture imaju dokazano važnu ulogu u začetku, poticanju i kontroli upalne reakcije koja je prema dosadašnjim istraživanjima temelj za razvoj i progresiju ateroskleroze, te su zanimljiv predmet budućih istraživanja.

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