Bone marrow deficiency of TRPC3 channel reduces early lesion burden and necrotic core of advanced plaques in a mouse model of atherosclerosis - PubMed (original) (raw)

Bone marrow deficiency of TRPC3 channel reduces early lesion burden and necrotic core of advanced plaques in a mouse model of atherosclerosis

Jean-Yves Tano et al. Cardiovasc Res. 2014.

Abstract

Aims: Macrophage apoptosis plays a determinant role in progression of atherosclerotic lesions. An important goal in atherosclerosis research is to identify new components of macrophage apoptosis that can eventually be exploited as molecular targets in strategies aimed at manipulating macrophage function in the lesion. In the previous work from our laboratory, we have shown that transient receptor potential canonical 3 (TRPC3) channel is an obligatory component of survival mechanisms in human and murine macrophages and that TRPC3-deficient non-polarized bone marrow-derived macrophages exhibit increased apoptosis, suggesting that in vivo TRPC3 might influence lesion development. In the present work, we used a bone marrow transplantation strategy as a first approach to examine the impact of macrophage deficiency of TRPC3 on early and advanced atherosclerotic lesions of Apoe(-/-) mice.

Methods and results: After 3 weeks of high-fat diet, lesions in mice transplanted with bone marrow from Trpc3(-/-) donors were smaller and with reduced cellularity than controls. Advanced lesions from these mice exhibited reduced necrotic core, less apoptotic macrophages, and increased collagen content and cap thickness. In vitro, TRPC3-deficient macrophages polarized to the M1 phenotype showed reduced apoptosis, whereas both M1 and M2 macrophages had increased efferocytic capacity.

Conclusions: Bone marrow deficiency of TRPC3 has a dual beneficial effect on lesion progression by reducing cellularity at early stages and necrosis in the advanced plaques. Our findings represent the first evidence for a role of a member of the TRPC family of cation channels in mechanisms associated with atherosclerosis.

Keywords: Atherosclerosis; Calcium channels; Macrophage apoptosis; TRPC3 channel.

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Figures

Figure 1

Figure 1

Aortic root sections from Trpc3+/+Apoe−/−BM→Apoe−/− or Trpc3−/−Apoe−/−BM→Apoe−/− mice on a 3-week high-fat diet were stained with haematoxylin–eosin (A), or Oil-Red-O (B) to evaluate lesion area and lipid content, respectively. Quantifications of mean stained areas are shown. Trpc3+/+Apoe−/−BM→Apoe−/− (n = 11–12), Trpc3−/−Apoe−/− BM→Apoe−/− (n = 13–14).

Figure 2

Figure 2

Aortic root sections from Trpc3+/+Apoe−/−BM→Apoe−/− or Trpc3−/−Apoe−/−BM→Apoe−/− mice on an 8-week high-fat diet were stained with haematoxylin–eosin (A), or Oil-Red-O (B). Quantifications of mean stained areas are shown. Trpc3+/+Apoe−/−BM→Apoe−/− (n = 13), Trpc3−/−Apoe−/− BM→Apoe−/− (n = 10–11).

Figure 3

Figure 3

Aortic root sections from Trpc3+/+Apoe−/−BM→Apoe−/− or Trpc3−/−Apoe−/−BM→Apoe−/− mice maintained on an 8-week high-fat diet were stained with Masson's trichrome to evaluate collagen content (blue) and necrosis. Representative sections are shown in (A). (B) The mean per cent collagen content relative to the lesion area. (C) Cap thickness, measured from largest necrotic cores (n = 32 for Trpc3+/+Apoe−/−; n = 21 for Trpc3−/−Apoe−/−) from 10 to 13 mice per group.

Figure 4

Figure 4

(A) Aortic root sections from Trpc3+/+Apoe−/−BM→Apoe−/− or Trpc3−/−Apoe−/−BM→Apoe−/− mice maintained on a high-fat diet for 8 weeks were stained for in situ TUNEL to detect apoptotic cells (arrows). In (B) representative merged images are shown of sections co-stained for macrophage (green, AIA31240), TUNEL, and DAPI. _P_-values were determined using the Mann–Whitney U test.

Figure 5

Figure 5

(A) Bone marrow-derived Trpc3+/+Apoe−/− or Trpc3−/−Apoe−/− macrophages differentiated to the M1 phenotype were incubated (24 h) in serum-free RPMI (RPMI) or RPMI containing oxidized-LDL (oxLDL, 50 µg/mL) or thapsigargin (1 µM), and processed for the TUNEL assay. ‘ns’: not statistically significant. Values are means ± SEM (n = 3). (B) Apoptotic non-polarized (M0) BMDMs from Trpc3+/+Apoe−/− mice were labelled with Calcein green and added to Trpc3+/+Apoe−/− or Trpc3−/−Apoe−/− M1 or M2 macrophages to evaluate efferocytosis. Shown are means ± SEM values (n = 3).

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