Transkriptom leve komore srca pacova sa doksorubicinskom kardiomiopatijom

Abstract

Kardiomiopatija predstavlja najozbiljnije neželjeno dejstvo doksorubicina, citostatika koji ima široku upotrebu. Nažalost, trenutno ne postoji dovoljno efikasna terapija za kardiomiopatiju indukovanu doksorubicnom. Cilj ovog istraživanja je potvrda modela doksorubicinske kardiotoksičnosti, identifikovanje fenotipova i njihovo povezivanje sa ekspresijom gena u srčanom tkivu. Mužjacima Wistar pacova je ugrađen radiotelemetrijski transmiter, a zatim su nasumično raspoređeni u eksperimentalnu (5 mg/0,5 mL/kg, I.V. doksorubicin; n=18) i kontrolnu grupu (0,5 mL/kg I.V. fiziološki rastvor; n=6). Ehokardiografsko merenje, procena autonomnih spektralnih markera i funkcije barorefleksa su rađeni pre tretmana i na samom kraju protokola. Krv je sakupljana po završetku protokola. Tkiva srca, bubrega i jetre su histološki analizirani posle smrti jedinki. Ehokardiografski, biohemijski i autonomni parametri su korišćeni za identifikovanje fenotipova fenomapiranjem metodom mašinskog učenja. Ekspresija gena je merena RT-qPCR metodom. Identifikovana su dva glavna fenotipa kod jedinki koje su razvile doksorubicinsku kardiomiopatiju. Fenotip 1 karakteriše pad ejekcione frakcije leve komore, dilatacija leve komore, stanjenje zida leve komore, pad srčane frekvence, povećanje senzitivnosti barorefleksa i NT-proBNP-a. Fenotip 2 karakteriše očuvana ejekciona frakcija leve komore, hipetrofija i povećanje mase leve komore, očuvane vrednosti srčane frekvence, povećanje senzitivnosti barorefleksa i umereno povećanje NT- proBNP-a. U obe grupe je primećen pad ekspresije gena za MYH6, odnosa MYH6 i MYH7, APLN, APLNR, COL1A1, TTN, MYBPC3 i VACM1, odnosno porast ekspresije gena za MYH7 i CTFG. Ipak, između grupa nije bilo razlike u ekspresiji gena, te nije bilo moguće identifikovanje dva genotipa.

Cardiomyopathy is the most serious adverse effect of doxorubicin (dox), widely used cytostatic drug. Unfortunately, at present, there is no efficient treatment for doxorubicin-induced cardiomyopathy (DCM). The aim of the present work was to affirm the experimental model of DCM in rats, to distinct phenotypes and associate them to the changes in cardiac transcriptome. Male Wistar rats equipped with radiotelemetry device, were randomized in DOX group (5 mg/0,5 mL/kg, IV dox; n=18) and CONT group (0,5 mL/kg IV saline; n=6). Echocardiography, autonomic spectral markers and baroreceptor reflex evaluation was performed prior to, and after treatment. Blood samples were collected at the end of experimentation. Cardiac, renal and hepatic tissues were histologically analysed post-mortem. Echocardiografic, biochemical and cardiovascular autonomic spectral parameters were used to identified phenotypes by phenomapping, machine learning method. Changes in expression of cardiac genes affected by dox were assessed by RT-qPCR. The results emphasize the existence of two major phenotypes of DCM with comparably high mortality rates. Phenotype 1 is characterized by reduced left ventricular ejection fraction (LVEF), LV dilatation, thinning of LV posterior wall, decreased heart rate (HR), increased baroreceptor reflex sensitivity (BRS) and increased NT-proBNP. Phenotype 2 is characterized by preserved LVEF, LV hypertrophy, increased LV mass, no changes in HR, increased BRS and moderate NT-proBNP increase. Both phenotypes exhibited a decreased gene expression for MYH6, MYH6 and MYH7 ratio, APLN, APLNR, COL1A1, TTN, MYBPC3 and VACM1 and increased gene expression for MYH7 and CTFG. However, due to no difference in gene expression between those phenotypes, we could not identify two genotypes.