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.
Subject(s)
Atherosclerosis/immunology , Chlamydophila Infections/immunology , Tobacco Smoke Pollution , Animals , Apolipoproteins E/deficiency , Chlamydophila pneumoniae/immunology , Female , In Situ Nick-End Labeling , Membrane Glycoproteins/metabolism , Mice , Mice, Knockout , Myeloid Differentiation Factor 88/metabolism , OX40 Ligand , Phagocytosis/immunology , Tumor Necrosis Factors/metabolismABSTRACT
BACKGROUND AND OBJECTIVES: The World Health Organization recommends human immunodeficiency virus (HIV)-positive mothers in resource-poor regions heat-treat expressed breastmilk during periods of increased maternal-to-child transmission risk. Flash-heat, a "low tech" pasteurization method, inactivates HIV, but effects on milk protein bioactivity are unknown. The objectives were to measure flash-heat's effect on antimicrobial properties of lactoferrin, lysozyme, and whole milk and on the digestive resistance of lactoferrin and lysozyme. METHODS: Flash-heated and unheated breastmilk aliquots from HIV-positive mothers in South Africa were "spiked" with Staphylococcus aureus and Escherichia coli and then cultured for 0, 3, and 6 hours. Lysozyme and lactoferrin activities were determined by lysis of Micrococcus luteus cells and inhibition of enteropathogenic E. coli, respectively, measured spectrophotometrically. Percentages of proteins surviving in vitro digestion, lactoferrin and lysozyme activity, and bacteriostatic activity of whole milk in heated versus unheated samples were compared. RESULTS: There was no difference in rate of growth of E. coli or S. aureus in flash-heated versus unheated whole milk (p = 0.61 and p = 0.96, respectively). Mean (95% confidence interval) antibacterial activity of lactoferrin was diminished 11.1% (7.8%, 14.3%) and that of lysozyme by up to 56.6% (47.1%, 64.5%) by flash-heat. Digestion of lysozyme was unaffected (p = 0.12), but 25.4% less lactoferrin survived digestion (p < 0.0001). CONCLUSIONS: In summary, flash-heat resulted in minimally decreased lactoferrin and moderately decreased lysozyme bioactivity, but bacteriostatic activity of whole milk against representative bacteria was unaffected. This suggests flash-heated breastmilk likely has a similar profile of resistance to bacterial contamination as that of unheated milk. Clinical significance of the decreased bioactivity should be tested in clinical trials.
