TSP-1, TSP-2, and TSP-5 demonstrate sexual dimorphism in intimal hyperplasia in rats and mice

Thrombospondins (TSPs) are matricellular proteins involved in intimal hyperplasia (IH). We hypothesized that <i>1</i>) TSP-1, TSP-2, and TSP-5 are interdependent regarding their effects on vascular smooth muscle (VSMC) physiology; <i>2</i>) local or systemic knockout of <i>THBS1</i> or <i>THBS2</i> reduces IH, with its combination (<i>THBS1/2</i>) being most effective; <i>3</i>) local or systemic knockout of <i>THBS5</i> increases IH; and <i>4</i>) the effects of TSPs differ between males and females. In vitro, VSMCs were transfected with siRNA against <i>THBS1</i>, <i>THBS2</i>, <i>THBS5</i>, or <i>THBS1/2.</i> VSMC proliferation by TSP-1, TSP-2, or PDGF-BB was tested, and chemotaxis to TSP-1, TSP-2, TSP-5, or PDGF-BB was assessed. Sprague-Dawley male and female rats underwent carotid artery balloon injury with intraluminal treatment of saline or adeno-associated virus containing siRNA against <i>THBS1</i>, <i>THBS2</i>, <i>THBS1/2</i>, <i>THBS5</i>, or scrambled siRNA. Wild-type, <i>THBS1</i>, <i>THBS2</i>, or <i>THBS5</i> null male or female mice underwent carotid artery ligation. After 14 days (rat) or 28 days (mice), animals were perfusion-fixed, euthanized, and IH measured. In vitro, siRNA to <i>THBS1</i>, <i>THBS2</i>, <i>THBS1/2</i>, or <i>THBS5</i> decreased VSMC response to exogenous TSPs. The novel combined siRNA <i>THBS1/2</i> demonstrated the most robust decrease in proliferation and migration. In vivo, only male rats and mice had reduced IH with local or systemic knock down of <i>THBS1</i> or <i>THBS2</i> (<i>P</i> < 0.05), with combined siRNA to <i>THBS</i>1/2 having the most robust effect. Knockdown of <i>THBS5</i> increased IH only in female mice (<i>P</i> < 0.05). In conclusion, TSPs affect one another and demonstrate a sexual dimorphism that may explain differences between male and female IH.<b>NEW & NOTEWORTHY</b> Thrombospondins (TSPs) are matricellular proteins involved in intimal hyperplasia (IH). We demonstrate in vitro, TSP-1, TSP-2, and TSP-5 affect one another and influence vascular smooth muscle cell proliferation and migration. In vivo, using a rat and mouse model of IH, we show that TSPs demonstrate a sexual dimorphism that may explain differences between male and female IH. Particularly, TSP-1 and TSP-2 appear to be strong mediators of IH in males only.