In-stent restenosis is associated with proliferative skin healing and specific immune and endothelial cell profiles: results from the RACHEL trial

Introduction

In-stent restenosis (ISR) is a major challenge in interventional cardiology. Both ISR and excessive skin healing are aberrant hyperplasic responses, which may be functionally related. However, the cellular component underlying ISR remains unclear, especially regarding vascular homeostasis. Recent evidence suggest that novel immune cell populations may be involved in vascular repair and damage, but their role in ISR has not been explored. The aims of this study is to analyze (i) the association between ISR and skin healing outcomes, and (ii) the alterations in vascular homeostasis mediators in ISR in univariate and integrative analyses.

Methods

30 patients with ≥1 previous stent implantation with restenosis and 30 patients with ≥1 stent without restenosis both confirmed in a second angiogram were recruited. Cellular mediators were quantified in peripheral blood by flow cytometry. Skin healing outcomes were analyzed after two consecutive biopsies.

Results

Hypertrophic skin healing was more frequent in ISR patients (36.7%) compared to those ISR-free (16.7%). Patients with ISR were more likely to develop hypertrophic skin healing patterns (OR 4.334 [95% CI 1.044-18.073], p=0.033), even after correcting for confounders. ISR was associated with decreased circulating angiogenic T-cells (p=0.005) and endothelial progenitor cells (p<0.001), whereas CD4+CD28null and detached endothelial cells counts were higher (p<0.0001 and p=0.006, respectively) compared to their ISR-free counterparts. No differences in the frequency of monocyte subsets were found, although Angiotensin-Converting Enzyme expression was increased (non-classical: p<0.001; and intermediate: p<0.0001) in ISR. Despite no differences were noted in Low-Density Granulocytes, a relative increase in the CD16- compartment was observed in ISR (p=0.004). An unsupervised cluster analysis revealed the presence of three profiles with different clinical severity, unrelated to stent types or traditional risk factors.

Conclusion

ISR is linked to excessive skin healing and profound alterations in cellular populations related to vascular repair and endothelial damage. Distinct cellular profiles can be distinguished within ISR, suggesting that different alterations may uncover different ISR clinical phenotypes.

The Relationship between Proliferative Scars and Endothelial Function in Surgically Revascularized Patients

BACKGROUND

Proliferative scars are benign fibrotic proliferations which demonstrate abnormal wound healing in response to skin injuries. As postulated in the "response to injury hypothesis", atherosclerosis is also triggered by an endothelial injury. Keloid and atherosclerotic processes have many pathophysiological and cytological features in common.

AIMS

In this study, we investigated the relationship between proliferative scars and endothelial function in surgically revascularized patients. We aimed to test the hypothesis that atherosclerosis is a wound healing abnormality.

STUDY DESIGN

Cross-sectional study.

METHODS

Consecutive patients who were admitted to the cardiology outpatient clinic with a history of coronary artery bypass grafting operation were evaluated. Thirty-three patients with proliferative scars at the median sternotomy site formed the keloid group, and 36 age- and sex-matched patients with no proliferative scar at the median sternotomy site formed the control group. Endothelial function was evaluated by flow-mediated vasodilatation of the brachial artery via ultrasonograhic examination.

RESULTS

There is no signicant difference according to the demographic data, biochemical parameters, clinical parameters and number of grafts between keloid and control groups. Endothelial-dependent vasodila-tory response was lower in the keloid group than the control group (9.30±3.5 and 18.68±8.2, respectively; p=0.001).

CONCLUSION

This study showed that endothalial dysfunction, which is strongly correlated with atherosclerosis, was more prominent in patients with proliferative scars. As proliferative scars and atherosclerosis have many features in common, we might conclude that atherosclerosis is a wound healing abnormality.

Cellular viability, collagen deposition, and transforming growth factor β1 production among ultraviolet B-irradiated keloid fibroblasts

BACKGROUND

A keloid is a fibrous tumor produced by fibroblast hyperproliferation and excessive collagen accumulation due to overproduction of transforming growth factor β1 (TGF-β1). High keloid incidence is found among individuals with unexposed skin, especially in Negroid and Mongoloid people with high melanin contents in their skin. Because melanin serves as an ultraviolet B (UVB) light absorber, it is assumed that lack of UVB light penetration may play a role in the keloid pathomechanism. This study aimed to evaluate the effect that UVB irradiation to monolayer keloid fibroblasts has on cell proliferation, collagen deposition, and TGF-β1 production.

METHODS

Keloid fibroblasts were isolated from five patients who underwent surgical treatment. Monolayer cultures of more than three passages of keloid fibroblast were exposed to various dosages of UVB irradiation. Cellular viabilities were measured by MTT assay. Collagen depositions were measured by Sirius Red assay for nonsoluble collagen, and TGF-β1 production was measured by enzyme-linked immunoassay (ELISA). Data were analyzed by one-way analysis of variance (ANOVA).

RESULTS

Ultraviolet B 100 and 150 mJ/cm(2) were able to suppress keloid fibroblast viabilities and collagen accumulation significantly (P < 0.01). Significant suppression of TGF-β1 production required UVB irradiation of 150 mJ/cm(2) (P < 0.01).

CONCLUSIONS

Lack of UVB skin penetration influences the keloid pathomechanism. Ultraviolet B irradiation with a minimal dosage of 150 mJ/cm(2) is a promising method of keloid prevention and treatment.