PAI-1 Protein Drives Vascular Aging — Blocking It Reverses the Damage
A new study links elevated PAI-1 to accelerated arterial stiffness and shows that reducing or inhibiting PAI-1 protects the vasculature and extends lifespan.
Summary
Researchers at Northwestern University demonstrated that PAI-1 (encoded by SERPINE1) is both necessary and sufficient to drive vascular aging. Humans carrying a heterozygous loss-of-function SERPINE1 mutation had significantly lower arterial stiffness (pulse wave velocity) than matched controls. Mice engineered with the same mutation lived 17% longer and were protected against hypertension and aortic stiffening under eNOS-inhibitor stress. Conversely, mice overexpressing a stabilized form of PAI-1 showed accelerated cardiovascular aging. Single-cell transcriptomics revealed that PAI-1 reduction suppresses ECM regulators CCN1 and integrin-β1 and enriches a protective smooth muscle cell population. Pharmacological PAI-1 inhibition normalized blood pressure and reversed stress-induced arterial stiffness, pointing to PAI-1 as a druggable target for age-related cardiovascular disease.
Detailed Summary
Age-related cardiovascular disease (CVD) remains the leading cause of death worldwide, and arterial stiffness — measurable as pulse wave velocity (PWV) — is one of its earliest and most consequential manifestations. PAI-1, the protein product of the SERPINE1 gene, has long been known as a pro-thrombotic serpin, but accumulating evidence implicates it in cellular senescence and broader aging biology. This study systematically tested whether PAI-1 is causally responsible for vascular aging in both humans and mice.
The human arm of the study recruited 33 carriers of the rare heterozygous SERPINE1 c.699_700dupTA loss-of-function (LOF) founder mutation from the Swiss Amish community in Berne, Indiana, and 33 sex- and age-matched non-carrier controls. After adjusting for age and sex, PWV was 1.18 m/s lower in LOF carriers — a difference linked epidemiologically to meaningfully reduced all-cause mortality risk. Both sexes showed the effect, and the age-related rise in PWV occurred at the same rate in both genotypes, indicating a constant protective offset rather than a slowed aging trajectory.
Using CRISPR-Cas9 editing on C57BL/6J mice, the team engineered the identical TA dinucleotide duplication in murine Serpine1 exon 4, producing Serpine1TA700/+ heterozygotes with ~50% lower circulating PAI-1 antigen. Aged heterozygotes (>85 weeks) showed ~20% lower PWV than wild-type littermates, and overall survival was extended by 17%. Under l-NAME (eNOS inhibitor) treatment — a validated model of aging-like endothelial dysfunction — Serpine1TA700/+ mice were protected against rises in PWV, systolic blood pressure, and the diastolic dysfunction index E/e′, while wild-type mice showed significant deterioration in all three measures. Critically, the l-NAME-induced PWV values in wild-type mice matched those of naturally aged mice, validating the model's relevance to chronological aging.
To confirm sufficiency, the investigators used a complementary mouse line expressing a stabilized human PAI-1 transgene (SERPINE1StabOE). These mice already exhibited elevated systolic blood pressure and diastolic dysfunction at 12 weeks of age, and all three cardiovascular aging metrics worsened further by 24 weeks — demonstrating that excess PAI-1 alone can accelerate vascular aging phenotypes even in young animals. Single-cell RNA sequencing of Serpine1TA700/+ aortas identified a vascular-protective transcriptional program: downregulation of extracellular matrix regulators CCN1 (Ccn1) and integrin-β1 (Itgb1), and enrichment of a smooth muscle cell (SMC) subpopulation displaying phenotypic plasticity associated with vessel homeostasis. Finally, pharmacological inhibition of PAI-1 with a small-molecule inhibitor both normalized systolic blood pressure and reversed l-NAME-induced arterial stiffening, providing proof-of-concept for therapeutic intervention.
Taken together, the study establishes a bidirectional, causal relationship between PAI-1 levels and vascular aging: reducing PAI-1 is protective while elevating it is pathological. The concordance of findings across human genetics, engineered mouse models, transcriptomics, and pharmacological intervention substantially strengthens the case for PAI-1 inhibition as a strategy to combat age-related CVD.
Key Findings
- Humans with heterozygous SERPINE1 LOF mutation had PWV ~1.18 m/s lower than age- and sex-matched controls.
- Engineered Serpine1TA700/+ mice lived 17% longer and showed ~20% lower aortic PWV in old age.
- PAI-1-overexpressing mice developed accelerated hypertension and diastolic dysfunction by 12 weeks of age.
- Single-cell transcriptomics linked PAI-1 reduction to downregulation of ECM regulators CCN1 and integrin-β1.
- Pharmacological PAI-1 inhibition normalized blood pressure and reversed l-NAME-induced arterial stiffening.
Methodology
The study combined a matched human cohort study (n=66) of SERPINE1 LOF mutation carriers vs. controls with CRISPR-engineered heterozygous and homozygous Serpine1 knock-in mice, a PAI-1-overexpressing transgenic mouse model, l-NAME pharmacological vascular stress testing, bulk and single-cell RNA sequencing of aortic tissue, and small-molecule PAI-1 inhibitor rescue experiments. Cardiovascular phenotyping included pulse wave velocity, systolic blood pressure via tail-cuff, and echocardiographic diastolic function (E/e′).
Study Limitations
The human cohort is drawn from a genetically isolated founder population (Swiss Amish), which may limit generalizability to broader populations. Mouse experiments rely on transgenic overexpression and pharmacological eNOS inhibition as aging surrogates rather than natural lifespan aging throughout. The specific small-molecule PAI-1 inhibitor used was tested only in the l-NAME stress model, and longer-term safety and efficacy data in humans are lacking.
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