Selective evaluation of high density lipoprotein from mouse small intestine by an in situ perfusion technique

Satoshi Yamaguchi,Bo Zhang,Takeshi Tomonaga,Utako Seino,Akiko Kanagawa,Masaru Segawa,Hironori Nagasaka,Akira Suzuki,Takashi Miida,Sohsuke Yamada,Yasuyuki Sasaguri,Takefumi Doi,Keijiro Saku,Mitsuyo Okazaki,Yoshihiro Tochino,Ken-Ichi Hirano

doi:10.1194/jlr.m047761

Abstract

The small intestine (SI) is the second-greatest source of HDL in mice. However, the selective evaluation of SI-derived HDL (SI-HDL) has been difficult because even the origin of HDL obtained in vivo from the intestinal lymph duct of anesthetized rodents is doubtful. To shed light on this question, we have developed a novel in situ perfusion technique using surgically isolated mouse SI, with which the possible filtration of plasma HDL into the SI lymph duct can be prevented. With the developed method, we studied the characteristics of and mechanism for the production and regulation of SI-HDL. Nascent HDL particles were detected in SI lymph perfusates in WT mice, but not in ABCA1 KO mice. SI-HDL had a high protein content and was smaller than plasma HDL. SI-HDL was rich in TG and apo AIV compared with HDL in liver perfusates. SI-HDL was increased by high-fat diets and reduced in apo E KO mice. In conclusion, with our in situ perfusion model that enables the selective evaluation of SI-HDL, we demonstrated that ABCA1 plays an important role in intestinal HDL production, and SI-HDL is small, dense, rich in apo AIV, and regulated by nutritional and genetic factors.

Highlights

The small intestine (SI) is the second-greatest source of HDL in mice
ABCA1, mutations of which are the genetic cause of Tangier disease and genetic HDL deficiency, is one of the Abbreviations: ACN, acetonitrile; CE, cholesterol ester; CETP, cholesteryl ester transfer protein; C-HDL, HDL in mesenteric lymph obtained by conventional intestinal lymph cannulation experiments; CM, chylomicron; EM, electron microscopy; FC, free cholesterol; HDL-C, HDL cholesterol; L-HDL, HDL in liver perfusates; P-HDL, plasma HDL; PL, phospholipid; SI, small intestine; SI-derived HDL (SI-HDL), small-intestine-derived HDL; Total cholesterol (TC), total cholesterol; TEM, transmission electron microscopy
Because the source of HDL obtained from the mesenteric lymph duct of anesthetized rodents in vivo is either the secretion of HDL by SI or the filtration of HDL from plasma through the blood capillary-lymph loop into the intestinal lymph duct [19,20,21,22], in our in situ perfusion model the arterial blood supply for the SI was blocked by ligation of the abdominal aorta and its branches (Fig. 1A) to dissociate the HDL produced by the SI from HDL filtered from plasma

Summary

Introduction

The small intestine (SI) is the second-greatest source of HDL in mice. the selective evaluation of SI-derived HDL (SI-HDL) has been difficult because even the origin of HDL obtained in vivo from the intestinal lymph duct of anesthetized rodents is doubtful. With our in situ perfusion model that enables the selective evaluation of SI-HDL, we demonstrated that ABCA1 plays an important role in intestinal HDL production, and SI-HDL is small, dense, rich in apo AIV, and regulated by nutritional and genetic factors.—Yamaguchi, S., B. Experimental studies with rodents have demonstrated that the liver and small intestine (SI) are the major organs for ABCA1 expression and HDL production [12,13,14,15,16]. Recent findings have shown that, the overexpression of hepatic ABCA1 in experimental mouse models is not beneficial [17], the overexpression of intestinal ABCA1 is beneficial for atherosclerosis [18], indicating that HDL from SI may perform unique and distinct functions

Methods

Results

Conclusion