Overexpression of the human heat shock protein B1 alters obesity-related metabolic changes in a sex-dependent manner in a mouse model of metabolic syndrome.

Abstract

Background: Obesity is a global health challenge that can lead to various complications, such as metabolic syndrome, diabetes mellitus, and cardiovascular diseases. Heat shock proteins are evolutionarily conserved chaperones that help maintain cellular protein homeostasis. Their expression is dysregulated in various chronic diseases, including diabetes mellitus and hyperlipidemia, and they also regulate inflammatory processes. Therefore, the present study aimed to investigate the effects of a small heat shock protein, HSPB1, on the comorbidities and complications of obesity in a transgenic mouse model.

Methods: Male and female human apolipoprotein B-100 (APOB) transgenic mice fed with a high-fat diet (HFD) from months 3-10 of age were used as a model of metabolic syndrome (MetS). To study whether HSPB1 influences the development of MetS, APOB animals were crossed with HSPB1-overexpressing mice. Age and sex-matched wild-type and human HSPB1-overexpressing mice were used as controls. Changes in cardiac morphology and function were assessed by transthoracic echocardiography at month 9. At month 10, serum triglyceride and cholesterol concentrations were determined by enzymatic colorimetric assays. Pathological changes in the liver were studied on hematoxylin-eosin-stained sections. Expression levels of genes involved in inflammation and metabolism were measured by quantitative real-time polymerase chain reaction in the liver, left ventricle, and visceral white adipose tissue (vWAT).

Results: The body weight and serum LDL-cholesterol levels were significantly higher in the APOB animals than in the wild-type mice in both sexes. Notably, HSPB1 overexpression further increased weight gain in female APOB animals. Conversely, in APOB males, HSPB1 overexpression decreased LDL-cholesterol levels without significantly affecting body weight. Furthermore, in APOB females, HSPB1 overexpression elevated Fgf-21 expression in the vWAT, restored Lpl levels, and reduced the expression of several cytokines in the liver. APOB males developed left ventricular hypertrophy (LVH) with diastolic dysfunction. HSPB1 overexpression induced LVH without cardiac dysfunction in the wild-type animals.

Conclusions: Both sexes of APOB animals developed MetS. APOB males presented LVH with preserved ejection fraction (EF); however, APOB females showed enlarged left ventricular end-systolic volume (LVESV). In APOB animals, HSPB1 overexpression exerted a sex-dependent influence on obesity-related alterations, including weight gain, hypercholesterolemia, and hepatic and vWAT gene expression.