Initial research on the effect and mechanism of Tivozanib on pulsed dye laser induced angiogenesis
Authors: Wang Bing , Zhang Yaqin , Lou Yan , Hu Xin , Li Fuqiu 
Published: August 2022

Introduction

Pulsed dye laser (PDL) is the main treatment for port wine stain (PWS), but a considerable number of patients show low clearances. The reason for the poor efficacy is related to PDL‐induced angiogenesis. Vascular endothelial growth factor (VEGF) plays an important role in PDL‐induced angiogenesis and can activate the tyrosine kinase activity of VEGF receptor (VEGFR) in endothelial cells. It triggers a full range of responses, and then participates in the regulation of angiogenesis. Tivozanib is an inhibitor of VEGFR tyrosine kinase activity, which can block the pro‐angiogenic effect of VEGF and reduce vascular permeability.

Method

Different energy densities of PDL were used to irradiate the abdominal skin of rats. According to the general and pathological changes of the irradiated area, the energy density of 8 J/cm2 with smaller scab and stronger vascular effect was selected for follow‐up experiments. Divided the rat abdomen skin into four areas, irradiated three of them uniformly with an energy density of 8 J/cm2, and applied different concentrations of Tivozanib coating agent to the laser irradiation area, and grouped them as follows: (1) vacant group, (2) control group, (3) 0.5% Tivozanib group, (4) 1% Tivozanib group. Camera and dermoscopy were used to observe skin changes. Hematoxylin‐eosin staining, immunohistochemical staining, and blood vessels were counted to detect dermal vascular regeneration. Transcriptome sequencing and real‐time polymerase chain reaction (PCR) were conducted to elucidate the mechanism and validate the reliability.

Results

The number of blood vessels in the 0.5% Tivozanib group and 1% Tivozanib group was significantly reduced on the 7, 10, and 14 days compared with the control group. The number of blood vessels in the 1% Tivozanib group was significantly reduced compared with the 0.5% Tivozanib group, indicating that Tivozanib successfully inhibited PDL‐induced angiogenesis, and the inhibitory effect of 1% Tivozanib was more significant than that of 0.5% Tivozanib. Transcriptome sequencing results showed a total of 588 significantly differentially expressed genes, including 90 upregulated genes and 498 downregulated genes. Gene ontology (GO) and kyoto encyclopedia of genes and genomes (KEGG) enrichment analysis showed that the significantly differentially expressed genes were mainly enriched in the metabolic pathways which were closely related to angiogenesis. Finally, real‐time PCR was used to verify the genes with higher expression differences, the top ranking and closely related to angiogenesis, namely, Cxcl1, Cxcl2, Cxcl3, Cxcl6, Ccl3, Csf3, IL1β, iNOS, Mmp9, Mmp13, Plau, Ets1, Spp1, Nr4a1. The results were consistent with the trend of transcriptome sequencing results, which proved the reliability of this study.

Conclusion

This study explored the inhibitory effect of Tivozanib on PDL‐induced angiogenesis, and provided a new idea for the treatment of clinical PWS. Transcriptome sequencing explored the mechanism and provided reliable clues for later in‐depth research.