Changes In Intestinal Flora Structure And Function Of Rats With Isoproterenol-induced Heart Failure Failure

Purpose:Recently,the potential role of gut microbiome in cardiovascular diseases has been revealed.Yet whether gut microbiota dysbiosis participates in the development of heart failure remains largely unknown.This study sought to investigate,if there are specific changes of the intestinal microbiome composition and function in isoproterenol-induced hear failure in rats,and disscuss the possibility of gut microbiome as a target to treat heart failure.At the same time,the expression of Ca MKIIδ and phosphorylated Ca MKIIδ in the heart failure tissues was detected.Methods:The rats were divided into C(control),4w-HF(Intraperitoneal injection of Isoproterenol 2.5mg/kg/d for 4weeks),2w-HF(Intraperitoneal injection of Isoproterenol 2.5mg/kg/d for 2 weeks)groups.(1)After the model was established,the cardiac structure and function was evaluated by echocardiography,the serum BNP was measured by ELISA,and HE staining to observe the pathological changes of myocardium to evaluate whether the HF model is established successfully.(2)After the HF models established successful,the feces of rats were collected,the stool DNA was extracted for Metagenomic sequencing and analyzing.The differences of intestinal flora structure and function between the three groups were compared.(3)Using Western Blotting to detect the protein expression of Ca MKII and phosphorylated Ca MKIIδ in each group.Results:(1)General modeling results:Compared with group C,rats in 4w-HF group generally experienced decreased feeding and activity,slower weight gain,and asthma appeared,while rats in 2w-HF group showed no obvious signs.4w-HF group died 2,2w-HF group died 1,C group did not die.(2)The IVSd,LVEDD and LVESD of4w-HF group and 2w-HF group were obviously higher than those of C group(P0.05),while the LVEF of 4w-HF group(56.03±1.72%)was lower than that of2w-HF group(73.03±1.19%)and C group(76.11±2.22%).(3)Plasma BNP content:Compared with C group(63.98±5.12pg/ml)and 2w-HF group(67.15±5.27pg/ml),the BNP level in 4w-HF group(188.48±21.64pg/ml)was clearly increased(P <0.01).(4)The heart mass index of 4w-HF group(3.49 + 0.14mg/g),2w-HF group(2.97 +0.13mg/g)and C group(2.14 + 0.10mg/g)had significant difference(P<0.01).(5)HE staining is observed under the microscope,it is found that control group cardiomyocytes are long spindle shaped and arranged in neat rows,boundaries between cells are clear,myocardial cells of the 4w-HF group showed disorder and irregularity,and exhibited overt hypertrophy,acidophilic degeneration or necrosis of myocardial cells.myocardial cells in the 2w-HF group is slightly hypertrophy,a few of degeneration or necrosis of myocardial cells.(6)Compared to the healthy controls,we found dramatically decreased the Shannon diversity index and microbial gene count in 4w-HF and 2w-HF groups.(7)High-throughput sequencing showed that intestinal bacterial community composition differed between the three groups;On the genus level,the most dominant genus in each group were all Prevotella,followed by Bacteroides;A overgrowth of bacteria such as Prevotella were observed in 4w-HF group,with reduced bacteria associated with healthy status such as Roseburia,Lactobacillus and Butyrivibrio,compared to controls on the genus level.(8)Concomitant with the alteration of gut microbial composition,underrepresent of health-linked microbial function such as amino acid biosynthesis and transport,sugar nucleotide biosynthesis and citric acid cycle were observed in both 4w-HF and2w-HF groups compared to controls.(9)Blotting Western shown: the expression of Ca MKIIδ,phosphorylated Ca MKIIδ,in 4w-HF group are significantly increased compared to control group(P<0.01).Conclusions:Isoproterenol-induced heart failure rats showed a significantly decreased diversity and richness of the intestinal microbiome,with a downregulation of key intestinal bacterial groups and overgrowth of some bacteria considered to be be involved in the inflammatory response,as well as a decreased of health-linkedmicrobial function.Our data point to an altered intestinal microbiome as a potential player in the pathogenesis and progression of heart failure.