Walnut peptide relieves hypertension and associated kidney and heart injury by regulating the renin–angiotensin–aldosterone system and intestinal microbiota

Abstract

BACKGROUND: Hypertension is a chronic disease with high morbidity and mortality. Previously, we screened a walnut meal peptide FDWLR (PEP) with significant angiotensin-converting enzyme inhibitory activity. The present study further investigated the anti-hypertensive effects of PEP in vivo using spontaneously hypertensive rats. RESULTS: The results indicated that PEP reduced blood pressure and the indices in the renin-angiotensin-aldosterone system (RAAS) including angiotensin-converting enzyme (ACE) (decreased by 15.36%), angiotensin II (Ang II) (decreased by 31.56%), angiotensinogen (AGT) (decreased by 58.84%) and aldosterone (ALD) (decreased by 18.27%), whereas NO levels increased by 54.96%. The pathological analysis showed that PEP relieved cardiac and renal damage. PEP also alleviated oxidative stress, inflammation and fibrosis in the heart and kidney. Mechanistically, PEP mitigated cardiac and renal damage by simultaneously regulating ACE-Ang II-AT1R and the ACE2-Ang (1-7)-MAS axis. Additionally, PEP increased the levels of short chain fatty acids by 224.16% and improved gut microbiota by increasing the abundance of Prevotella, Phascolarctobacterium, Clostridium_sensu_stricto and Bifidobacterium, at the same time as decreasing Bacteroides and Alistipes abundances. CONCLUSION: This study indicated that PEP prevented hypertension and associated heart and kidney damage by modulating the RAAS system and gut microbiota, which is valuable in guiding future development and optimal utilization of walnut meal. © 2024 Society of Chemical Industry.