Plasma levels of soluble Flt-1 and Tie-2 correlate with neovascularization in human carotid atherosclerotic plaques - a pilot study.
To determine whether circulating soluble Flt-1 (sFlt-1) and soluble Tie-2 (sTie-2) are associated with intraplaque neovascularization (IPN) in human carotid atherosclerotic plaques.
Forty-four patients with ≥50% carotid stenosis underwent conventional carotid ultrasound and superb microvascular imaging (SMI); 29 had plasma collected and 11 provided carotid endarterectomy specimens for histology. IPN was quantified as neovessel counts in 2-minute SMI cine loops and as microvessel counts in excised plaques. Plasma VEGF-A/B/C/D, Ang-2, sFlt-1, and sTie-2 were measured by immunoassays. Public single-cell RNA-seq data from human carotid plaques were interrogated to map FLT1, TEK, VEGFA, ANGPT1, and ANGPT2 expression to specific plaque cell populations.
IPN was detected in 33/44 (75%) patients, with 0-16 neovessels on SMI (median 4). Plasma sFlt-1 correlated with SMI neovessel counts (r=0.42, p=0.030), with a similar trend for sTie-2 (r=0.37, p=0.057), whereas VEGF-A/B/C/D and Ang-2 showed no significant relationships. In the surgical subgroup, histological neovessel counts correlated with sFlt-1 (r=0.65, p=0.030) and SMI neovessel count (r= 0.68, p =0.02) but not sTie-2. sFlt-1 and sTie-2 correlated with BMI (and sTie-2 also with age), yet log-sFlt-1 remained independently associated with SMI-derived neovessel counts after adjustment for age and BMI (B = 13.24, 95% CI 0.17-26.30, p=0.047; R²=0.18), while sTie-2 was not. No significant associations were observed between IPN or sFlt-1/sTie-2 and lipid profile, CRP, leukocyte counts, or other conventional risk factors. Single-cell transcriptomics showed FLT1 and ANGPT2 broadly expressed across endothelial, smooth-muscle, and myeloid clusters, with TEK largely confined to endothelial cells and ANGPT1 to smooth-muscle cells, supporting local activation of VEGF-FLT1 and Ang-TEK/Tie-2 signaling within plaques.
In this pilot study, higher plasma sFlt-1, and, to a lesser degree sTie-2, correlated with carotid IPN on SMI and histology, independent of age and BMI. These findings suggest that soluble VEGF- and Ang/Tie-2-receptor pathways may serve as circulating, context-sensitive markers of intraplaque angiogenesis and plaque vulnerability, meriting evaluation in larger longitudinal cohorts.
Forty-four patients with ≥50% carotid stenosis underwent conventional carotid ultrasound and superb microvascular imaging (SMI); 29 had plasma collected and 11 provided carotid endarterectomy specimens for histology. IPN was quantified as neovessel counts in 2-minute SMI cine loops and as microvessel counts in excised plaques. Plasma VEGF-A/B/C/D, Ang-2, sFlt-1, and sTie-2 were measured by immunoassays. Public single-cell RNA-seq data from human carotid plaques were interrogated to map FLT1, TEK, VEGFA, ANGPT1, and ANGPT2 expression to specific plaque cell populations.
IPN was detected in 33/44 (75%) patients, with 0-16 neovessels on SMI (median 4). Plasma sFlt-1 correlated with SMI neovessel counts (r=0.42, p=0.030), with a similar trend for sTie-2 (r=0.37, p=0.057), whereas VEGF-A/B/C/D and Ang-2 showed no significant relationships. In the surgical subgroup, histological neovessel counts correlated with sFlt-1 (r=0.65, p=0.030) and SMI neovessel count (r= 0.68, p =0.02) but not sTie-2. sFlt-1 and sTie-2 correlated with BMI (and sTie-2 also with age), yet log-sFlt-1 remained independently associated with SMI-derived neovessel counts after adjustment for age and BMI (B = 13.24, 95% CI 0.17-26.30, p=0.047; R²=0.18), while sTie-2 was not. No significant associations were observed between IPN or sFlt-1/sTie-2 and lipid profile, CRP, leukocyte counts, or other conventional risk factors. Single-cell transcriptomics showed FLT1 and ANGPT2 broadly expressed across endothelial, smooth-muscle, and myeloid clusters, with TEK largely confined to endothelial cells and ANGPT1 to smooth-muscle cells, supporting local activation of VEGF-FLT1 and Ang-TEK/Tie-2 signaling within plaques.
In this pilot study, higher plasma sFlt-1, and, to a lesser degree sTie-2, correlated with carotid IPN on SMI and histology, independent of age and BMI. These findings suggest that soluble VEGF- and Ang/Tie-2-receptor pathways may serve as circulating, context-sensitive markers of intraplaque angiogenesis and plaque vulnerability, meriting evaluation in larger longitudinal cohorts.
Authors
Zamani Zamani, Skagen Skagen, Lindberg Lindberg, Bjerkeli Bjerkeli, Dahl Dahl, Michelsen Michelsen, Ueland Ueland, Aukrust Aukrust, Halvorsen Halvorsen, Skjelland Skjelland
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