Molecular background of impairments in skeletal muscle of heart failure patients

Background

Heart failure (HF) is characterised by systematic inflammation and chronic metabolic dysregulation. HF enhances the release of pro-inflammatory cytokines, induces activation of the complement system, production of autoantibodies, and over-expression of the major histocompatibility (MHC) complex class II molecules. It is known that skeletal muscles are exposed to the immunologic injury in disease; and muscle tissue appeared to be affected by HF leading to the muscle weakness and exercise intolerance development. However, molecular abnormalities occurring in HF patients' muscles and the mechanisms underlying its development are not clarified.

Purpose

To understand the molecular mechanisms underlying skeletal muscle immune and non-immune impairments in HF.

Methods

8 health donors and 5 HF patients with reduced ejection fraction (NYHA Class II and III) were enrolled in this study in accordance with the principles under the Declaration of Helsinki (1989). mRNA of skeletal muscle biopsies of gastrocnemius lateralis were sequenced on Illumina HiSeq. RNA-seq analysis was performed using STAR with reference genome GRCh38 and featureCounts program; differentially expressed genes (DEGs) were assessed using R package DESeq2 with FDR=0.01 and log2 fold change (l2fc) >1.5 filter; pathway analysis was performed using clusterProfiler in R (FDR=0.01).

Results

1404 differentially expressed genes distinguish muscles of HF patients and controls. Among upregulated genes there are different classical MHC molecules and specific one HLA-G (l2fc=2) that has been previously shown appeared in muscles under autoimmune myopathies, and potentially protect them. Unregulated DEGs were responsible for the activation of many molecular immunological pathways: type I interferon signaling pathway (16 DEGs out of total 89), regulation of T cell proliferation (14/153), neutrophil degranulation (31/485), granulocyte differentiation (7/32), negative regulation of viral process (11/53), that indicates about specific inflammatory response in HF muscles. Response to hypoxia (22/314) and gluconeogenesis pathways (12/87) were also activated. Downregulated genes include SLC5A1 (l2fc=−4) sodium glucose cotransporter; NRP3 (l2fc=−4) that plays a role in modulating intravascular volume and vascular tone; MMP1 (l2fc=−13) involved in the breakdown of extracellular matrix; the expression of many genes responsible for DNA-repair (44/534) and cilium assembly (34/366) was also suppressed.

Conclusion

Transcriptome analysis shows immunological and non-immunological alterations in HF skeletal muscles and provides the information about molecular mechanisms of its development.

Funding Acknowledgement

Type of funding sources: Foundation. Main funding source(s): Russian Science Foundation grant

[Results of 3 years work of the Russian hospital register of chronic heart failure (RUssian hoSpital Heart Failure Registry - RUS-HFR): relationship between management and outcomes in patients with chronic heart failure]

AIM

To analyze management and outcomes in patients with CHF managed by specialists in heart failure (HF) or general cardiologists/physicians in real-life clinical practice.

MATERIALS AND METHODS

Survival rate, rehospitalization rate, general health condition, and the administered therapy were evaluated for HF patients with reduced LV ejection fraction at three years of discharge from cardiological hospitals. These patients had been included in a prospective, multicenter, observational study, "The Russian Hospital HF Registry" (RUS-HFR). The first group consisted of patients who were managed at a specialized HF department of the Federal Center and followed up at the outpatient stage by a cardiologist specializing in HF (Group 1, St.‑Petersburg; n =74). The other two groups (Group 2 and Group 3) included patients who were managed at other cardiological departments of the Federal Center (n=186) or the Regional Center (n=130) and subsequently followed up at the place of residence.

RESULTS

After the discharge from the hospital, 58-95 and 12-19% of RUS-HFR patients were followed up by a cardiologist or a physician, respectively, on an outpatient basis while 5-23% of patients did not visit a doctor at all. In three years, the survival rate of Group 1, 2, and 3 patients was 80 vs. 78 (р>0.05) vs. 52% (р0.05) vs. 100% (p1,2.

[Response predictors for physical training HFrEF patients]

PURPOSE

To identify different types and possible predictors of physical rehabilitation (PR) response in reduced ejection fraction heart failure (HFrEF) patients, selected on the basis of achievement the lactate threshold during cardiopulmonary exercising test (CPET).

METHODS

64 patients, chronic heart failure (CHF) NYHA II-III functional class were included in our study. Mean age 54±12,5 years, body mass index (BMI) 26,5±6,4 kg/m2, ejection fraction (EF) 26,4±1,4 %, NYHA II: III (67 %: 33 % patients). The original estimated results of physical examination, laboratory parameters, CPET, quality of life (QOL), exercise tolerance (ET) and echocardiography (EchoCG). Physical rehabilitation (PR) efficiency was estimated on the basis of peak oxygen uptake (VO2peak), QOL and ET dynamics after 1,3 and 6 months; EF dynamics was estimated after 6 months. Data were statistically processed using software package "Statistika, 9.0".

RESULTS

After 6 months PR EF increased by 7,5±0,5 %, QOL - 17.5±8 points, ET - 9.5±1 points and VO2 peak - 4.4 ml/min/kg, end-diastolic volume decreased by 6±2.0 ml from baseline (p1,2,3,4, respectively). Echocardiography, CPET, QOL and ET improvement revealed a significant number of patients (EF - 48 %, VO2 peak - 64 %, QOL - 64 %, ET - 67 % of patients, respectively). Revealed a strong positive correlation between the initial values of VO2 peak and EF (rEF=0,4, p), and between baseline levels of sodium, haemoglobin and the of PR efficiency (rNa= 0,41, p,0,05; rHb = 0,45, p.