Gut microbiota-dependent increase in phenylacetic acid induces endothelial cell senescence during aging

Abstract

Endothelial cell (EC) senescence plays a crucial role in the development of cardiovascular diseases in aging population. Gut microbiota alterations are emerging as significant factors present in cellular senescence associated with aging. However, little is known about how aging-related changes in gut microbiota are causally implicated in EC senescence. Here we show that gut microbiota-dependent phenylacetic acid (PAA) and its derivative, phenylacetylglutamine (PAGln), are elevated in a human aging cohort (TwinsUK, n=7,303) and in aged mice. Metagenomic analyses revealed a marked increase in the abundance of PAA-producing microbial pathways (PPFOR and VOR), which were positively associated with the abundance ofClostridiumsp. ASF356, higher circulating PAA concentrations, and endothelial dysfunction in old mice. We found that PAA potently induces EC senescence and attenuates angiogenesis. Mechanistically, PAA increases mitochondrial H2O2generation, which aggravates IL6-mediated HDAC4 translocation and thereby upregulates VCAM1. In contrast, exogenous acetate, which was reduced in old mice, rescues the PAA-induced EC senescence and restores angiogenic capacity through markedly alleviating the SASP and epigenetic alteration. Our studies provide direct evidence of PAA-mediated crosstalk between aging gut microbiota and EC senescence and suggest a microbiota-based therapy for promoting healthy aging.HighlightsAging-related gut microbiota alterations contribute to a marked elevation of plasma PAA and PAGln in humans and miceClostridiumsp. ASF356 contributes to PPFOR-mediated PAA formation in aged miceGut-derived PAA promotes endothelial senescence and impairs angiogenesisPAA induces mitochondrial H2O2generation, by which drives epigenetic alterations and SASP in ECsAcetate rescues PAA-induced EC senescence and mitochondrial dysfunctionAcetate improves angiogenesis by reducing HDAC4 phosphorylation and SASP

AQP1 Differentially Orchestrates Endothelial Cell Senescence

“…Excessive H 2 O 2 and other ROS within SECs disrupt the phosphorylation responses of these protein kinases. This observation aligns with our recent studies indicating that CaMKII phosphorylation declined in SECs, in which mitochondrial ROS induces oxidative stress [22]. The diminished CaMKII phosphorylation due to oxidative stress can impair its downstream signaling cascades, contributing to endothelial dysfunction [55].…”

“…Moreover, oxidized HDAC4 has been shown to interact more easily with protein kinases of the CaMKII family. Consistently, our prior investigation demonstrated that gut-derived phenylacetic acid, by NOX4-mediated H 2 O 2 generation, both oxidizes and phosphorylates (through CaMKII stimulation) HDAC4, facilitating its cytosolic accumulation in PECs [22]. We next observed that HDAC4 nuclear export facilitates de-repression of Mef2A in PECs.…”

“…Corroborating our findings, excessive H 2 O 2 -induced oxidative stress shuts down mitochondrial oxidative phosphorylation, resulting in impaired ATP biosynthesis in SECs [22,48]. This substantiates the occurrence of mitochondrial metabolic alterations in these cells, potentially contributing to diminished cell migration and compromised angiogenic capacity.…”

“…EC senescence is intricately characterized by profound epigenetic alterations, particularly histone modifications, contributing to dynamic comprehensive changes of gene expression profiles that orchestrate the progression of vascular aging [22,30]. HDAC4 is a key regulator of histone modifications and subsequent expression of the genes involved in senescence-associated phenotypes in endothelial cells [22,31]. Our and others studies suggest that post-translational modification of HDAC4 may modulate histone acetylation states, impacting gene expression patterns associated with endothelial cell senescence and impaired angiogenesis [22,32].…”

“…1D,E, cellular senescence, as a hallmark of aging, is associated with significant AQP1 upregulation in SECs as opposed to PECs. AQP1 has been recognized to transport H 2 O 2 in specific cell types [13], which may promote premature cellular senescence [21,22]. To prove the role of AQP1 in regulation of H 2 O 2mediated EC senescence, we transduced PECs (control) with ultrasensitive H 2 O 2 biosensor, AV5-HyPer7.2-NES, and detected H 2 O 2 levels in the cell cytosol which was markedly reduced following siAQP1 transfection or treatment with a clinically approved AQP1 inhibitor, Bacopaside II, in the presence of exogenous H 2 O 2 (50 μM; Fig.…”