Exosome-like nanovesicle targeting visceral adipose tissue inflammation mitigates heart failure with preserved ejection fraction

Abstract Introduction Heart failure (HF) with preserved ejection fraction (HFpEF) is associated with chronic systemic inflammation and obesity, with limited therapies. Inflammation in visceral adipose tissue (VAT) was significantly evoked in obese mice; while mesenchymal stem cell (MSC), especially atorvastatin (ATV)-pretreated MSC, could promote anti-inflammatory phenotype switch of immunocytes (e.g. macrophages), serving as a promising therapy for obesity-related HFpEF. Thus, the study was designed to prepare a novel ATV-pretreated MSC-derived exosome-like nanovesicles (ELNVs) and assess the anti-inflammatory and cardioprotective effects of ELNVs. Methods ELNVs derived from unpretreated MSC (ELNVM) or ATV-pretreated MSC (ELNVMA) were prepared and characterized (Figure 1). PKH-26-labelled ELNVs were incubated with THP1 cells for cell uptake assay. For anti-inflammatory studies in vitro, ELNVs (5×1010/mL) were added into the medium, followed by the induction of M1 or M2 polarization. The expressions of iNOS and Arg1 were measured by immunofluorescence (IF) staining. A 2-hit preclinical mice model of HFpEF, established by a 12-week high-fat diet (HFD) and Nω-Nitro-L-arginine methyl ester hydrochloride administration (0.5 g/L), was applied and received normal saline (NS) or ELNVs (i.p., 5×1011/kg body weight, 3 times a week). Functional and histological analysis including echocardiography, exhaustion test, WGA staining for hearts and western blot for VAT were performed. Quantitative polymerase chain reaction (qPCR) of key long non-coding RNAs (lncRNAs) was used to identify the mediator in ELNVs. Results The mean diameters of ELNVM and ELNVMA were 109.5 and 114.6 nm respectively and both ELNV types could be taken by THP1 cells. VAT inflammation was activated in HFpEF mice compared to the control in terms of the protein levels of iNOS and Arg1. An elevated expression of Arg1 and a decreased level of iNOS was observed in THP1 cells in vitro and VAT in vivo in both ELNV groups (P<0.05, Figure 1 and 2). Consistently, levels of interleukin (IL)-1β were increased in VAT of HFpEF mice, which were downregulated in ELNVM and ELNVMA groups. Both ELNVs could reduce the E/E’, and attenuate cardiac hypertrophy (heart weight to tibial length) and pulmonary congestion (lung weight [wet to dry]) (all P<0.05), with more pronounced improvements in ELNVMA group (Figure 2). Results of qPCR indicated three lncRNA candidates (TARID, H19 and KLF3-AS1) that were previously reported to inhibit M1 polarization or promote M2 polarization, were elevated in ELNVMA compared to ELNVM (P<0.05). Conclusion VAT inflammation was evoked in HFpEF mice and contributed to the development of HFpEF. This pilot study developed a novel ATV-pretreated ELNVs, which might serve as a promising tool for alleviating HFpEF due to the charming anti-inflammatory and cardioprotective effects mediated by regulating VAT macrophages.Figure 1.ELNVs’ PreparationFigure 2.Anti-inflammation of ELNVs