A combination of secondhand cigarette smoke and Chlamydia pneumoniae accelerates atherosclerosis

Xiaoyan Zhao, De xiu Bu, Kweku Hayfron, Kent E Pinkerton, Charles L Bevins, Andrew Lichtman, Jean A Wiedeman

Research output: Contribution to journalArticle

13 Citations (Scopus)

Abstract

Objective: Secondhand smoke (SS) induces chronic infection of endothelial cells by Chlamydia pneumoniae (Cpn) in vitro. We investigated the in vivo effect on atherosclerosis following exposure to SS and infection with Cpn both independently and in combination in ApoE-/- mice. Methods and results: Plaques were largest in the combined SS + Cpn-exposed mice with 12-57% greater cross-sectional area compared with all other groups (P< 0.03). Quantitative RT-PCR (qRT-PCR) from aortic roots revealed a synergistic upregulation of both OX40L (CD134L) and MyD88 in SS. +. Cpn mice (P< 0.05). This upregulation occurred despite decreased numbers of macrophage, dendritic cell, CD4 T cell and smooth-muscle-cell infiltrates as determined by quantitative IHC and qRT-PCR. To elucidate whether enhanced apoptosis correlated with reduced plaque cellularity, area of Tdt-mediated dUTP nick labeling positive (TUNEL+) cells and expression of key bridging molecules necessary for efferocytosis (Mertk, Tgm2, FasL and C1qa) were examined. In SS + Cpn mice, there was an increase of the area of TUNEL+ cells in plaque cores (P< 0.001) and a downregulation of efferocytosis gene expression (P< 0.05). Systemic expression of cytokines in sera (Luminex) showed no differences between groups, suggesting that focal disease mechanisms within the plaque predominated. Conclusions: The combination of SS exposure and Cpn infection enhanced atherosclerosis more than either variable did independently by activating inflammatory cells and by promoting growth and maturation of lesions via defective phagocytic clearance and accumulation of apoptotic cells.

Original languageEnglish (US)
Pages (from-to)59-66
Number of pages8
JournalAtherosclerosis
Volume222
Issue number1
DOIs
StatePublished - May 2012

Fingerprint

Chlamydophila pneumoniae
Tobacco Smoke Pollution
Tobacco Products
Atherosclerosis
In Situ Nick-End Labeling
Up-Regulation
Polymerase Chain Reaction
Chlamydia Infections
Apolipoproteins E
Infection
Dendritic Cells
Smooth Muscle Myocytes
Down-Regulation
Endothelial Cells
Macrophages
Apoptosis
Cytokines
T-Lymphocytes
Gene Expression
Growth

Keywords

  • Apoptosis
  • Atherosclerosis
  • Chlamydia pneumoniae
  • Secondhand smoke

ASJC Scopus subject areas

  • Cardiology and Cardiovascular Medicine

Cite this

A combination of secondhand cigarette smoke and Chlamydia pneumoniae accelerates atherosclerosis. / Zhao, Xiaoyan; Bu, De xiu; Hayfron, Kweku; Pinkerton, Kent E; Bevins, Charles L; Lichtman, Andrew; Wiedeman, Jean A.

In: Atherosclerosis, Vol. 222, No. 1, 05.2012, p. 59-66.

Research output: Contribution to journalArticle

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abstract = "Objective: Secondhand smoke (SS) induces chronic infection of endothelial cells by Chlamydia pneumoniae (Cpn) in vitro. We investigated the in vivo effect on atherosclerosis following exposure to SS and infection with Cpn both independently and in combination in ApoE-/- mice. Methods and results: Plaques were largest in the combined SS + Cpn-exposed mice with 12-57{\%} greater cross-sectional area compared with all other groups (P< 0.03). Quantitative RT-PCR (qRT-PCR) from aortic roots revealed a synergistic upregulation of both OX40L (CD134L) and MyD88 in SS. +. Cpn mice (P< 0.05). This upregulation occurred despite decreased numbers of macrophage, dendritic cell, CD4 T cell and smooth-muscle-cell infiltrates as determined by quantitative IHC and qRT-PCR. To elucidate whether enhanced apoptosis correlated with reduced plaque cellularity, area of Tdt-mediated dUTP nick labeling positive (TUNEL+) cells and expression of key bridging molecules necessary for efferocytosis (Mertk, Tgm2, FasL and C1qa) were examined. In SS + Cpn mice, there was an increase of the area of TUNEL+ cells in plaque cores (P< 0.001) and a downregulation of efferocytosis gene expression (P< 0.05). Systemic expression of cytokines in sera (Luminex) showed no differences between groups, suggesting that focal disease mechanisms within the plaque predominated. Conclusions: The combination of SS exposure and Cpn infection enhanced atherosclerosis more than either variable did independently by activating inflammatory cells and by promoting growth and maturation of lesions via defective phagocytic clearance and accumulation of apoptotic cells.",
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N2 - Objective: Secondhand smoke (SS) induces chronic infection of endothelial cells by Chlamydia pneumoniae (Cpn) in vitro. We investigated the in vivo effect on atherosclerosis following exposure to SS and infection with Cpn both independently and in combination in ApoE-/- mice. Methods and results: Plaques were largest in the combined SS + Cpn-exposed mice with 12-57% greater cross-sectional area compared with all other groups (P< 0.03). Quantitative RT-PCR (qRT-PCR) from aortic roots revealed a synergistic upregulation of both OX40L (CD134L) and MyD88 in SS. +. Cpn mice (P< 0.05). This upregulation occurred despite decreased numbers of macrophage, dendritic cell, CD4 T cell and smooth-muscle-cell infiltrates as determined by quantitative IHC and qRT-PCR. To elucidate whether enhanced apoptosis correlated with reduced plaque cellularity, area of Tdt-mediated dUTP nick labeling positive (TUNEL+) cells and expression of key bridging molecules necessary for efferocytosis (Mertk, Tgm2, FasL and C1qa) were examined. In SS + Cpn mice, there was an increase of the area of TUNEL+ cells in plaque cores (P< 0.001) and a downregulation of efferocytosis gene expression (P< 0.05). Systemic expression of cytokines in sera (Luminex) showed no differences between groups, suggesting that focal disease mechanisms within the plaque predominated. Conclusions: The combination of SS exposure and Cpn infection enhanced atherosclerosis more than either variable did independently by activating inflammatory cells and by promoting growth and maturation of lesions via defective phagocytic clearance and accumulation of apoptotic cells.

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