OBJECTIVETo observe the effect of Huanglian Jiedu Decoction (HLJDD) in in vivo regulating differentiation of monocytes in an apolipoprotein E knockout (ApoE(-/-)) mouse model, and to observe the effect of HLJDD-containing serum in in vitro regulating differentiation of macrophages and foam cells.

METHODSFifteen apoE(-/-) mice were randomly divided into the common diet group, the hyperlipidemia group, and the hyperlipidemia +HLJDD treatment group, 5 in each group. Mice in the common diet group were fed with a chow diet. Mice in the hyperlipidemia group were fed with high cholesterol wild diet (WD). Those in the hyperlipidemia +HLJDD treatment group were fed with high cholesterol WD supplemented with HLJDD. All mice were fed for 4 weeks. Five C57BL/6 wild types were recruited as the wild common diet control group. HLJDD was administered to mice in the hyperlipidemia + HLJDD treatment group by gastrogavage at the daily dose of 5 g/kg. Equal volume of purified water was given by gastrogavage to mice in the rest 3 groups. Four weeks later, subtypes of monocytes in the peripheral blood were detected by FACS. HLJDD administered to another 30 SD rats by gastrogavage at the daily dose of 5 g/kg, once for every 12 h for 5 times in total, thereby preparing 5% HLJDD containing serum to intervene the differentiation of in vitro primary bone marrow-derived macrophage (BMDM) and foam cells. The M2 subtype surface receptor CD206 of macrophages and foam cells were detected by FACS. The expression of Nos2 and Arg1 genes were assayed by Real-time PCR.

RESULTSThe ratio of inflammatory subset of monocytes (Ly6C(high)) increased in the peripheral blood after ApoE(-/-) mice were fed with high fat diet for 4 weeks. HLJDD significantly decreased the ratio of inflammatory subset of monocytes (P < 0.05). Compared with the vehicle serum, 5% HLJDD containing serum significantly increased differentiation of CD206 + M2 BMDM (P = 0.034). Results of real-time quantitative PCR showed that the expression level of Arg1 mRNA could be up-regulated by HLJDD containing serum (P < 0.05), and that of Nos2 mRNA down-regulated (P = 0.017). ox-LDL induced the differentiation of M2 subtype foam cells from BMDM, and HLJDD containing serum could further elevate the ratio of CD206 + M2 foam cells and increase the Arg1 mRNA expression level (both P < 0.01). HLJDD containing serum could inhibit the inversion of M2 subtype of foam cells to M1 subtype induced by Th1 factors, significantly elevate the Arg1 mRNA expression level, and decrease the Nos2 mRNA expression level (all P < 0.01).

CONCLUSIONSHLJDD could lower hyperlipidemia induced inflammatory monocyte subtype ratios in the peripheral blood of ApoE(-/-) mice. HLJDD containing serum promoted in vitro differentiation of M2 macrophages and foam cells. HLJDD attenuated and inhibited the occurrence and development of atherosclerosis induced by hyperlipidemia possibly through regulating the functional differentiation of monocytes, macrophages, and foam cells.