Apoptosis, autophagy and atherosclerosis: Relationships and the role of Hsp27

Atherosclerosis is a multifactorial chronic inflammatory disease of the arterial wall, and an important pathological basis of coronary heart disease. Endothelial cells, vascular smooth muscle cells, and macrophages play important roles in the development of atherosclerosis. Of note, apoptosis and autophagy, two types of programmed cell death, influence the development and progression of atherosclerosis via the modulation of such cells. The small heat shock protein Hsp27 is a multifunctional protein induced by various stress factors and has a protective effect on cells. A large number of studies have demonstrated that Hsp27 plays an important role in regulating apoptosis. Recently, some studies have suggested that Hsp27 also participates in the autophagic process. Moreover, Hsp27 is closely related to the occurrence and development of atherosclerosis. Here, we summarize the molecular mechanisms of apoptosis and autophagy and discuss their effects on endothelial cells, vascular smooth muscle cells, and macrophages in the context of atherosclerotic procession. We further explore the involvement of Hsp27 in apoptosis, autophagy, and atherosclerosis. We speculate that Hsp27 may exert its anti-atherosclerotic role via the regulation of apoptosis and autophagy; this may provide the basis for the development of new approaches for the prevention and treatment of atherosclerosis.

Therapeutic potential of polyphenols in cardiovascular diseases: Regulation of mTOR signaling pathway

Cardiovascular diseases comprise of non-communicable disorders that involve the heart and/or blood vessels and have become the leading cause of death worldwide with increased prevalence by age. mTOR is a serine/threonine-specific protein kinase which plays a central role in many physiological processes including cardiovascular diseases, and also integrates various proliferative signals, nutrient and energy abundance and stressful situations. mTOR also acts as central regulator during chronic stress, mitochondrial dysfunction and deregulated autophagy which are associated with senescence. Under oxidative stress, mTOR has been reported to exert protective effects regulating apoptosis and autophagy processes and favoring tissue repair. On the other hand, inhibition of mTOR has been suggested to have beneficial effects against atherosclerosis, cardiac hypertrophy and heart failure, and also in extending the lifespan. In this aspect, the use of drugs or natural compounds, which can target mTOR is an interesting approach in order to reduce the number of deaths caused by cardiovascular disease. In the present review, we intend to shed light on the possible effects and molecular mechanism of natural agents like polyphenols via regulating mTOR.

Caffeic acid reduces A53T α-synuclein by activating JNK/Bcl-2-mediated autophagy in vitro and improves behaviour and protects dopaminergic neurons in a mouse model of Parkinson's disease

The human A53T mutant of α-synuclein tends to aggregate and leads to neurotoxicity in familial Parkinson's disease (PD). The aggregation of α-synuclein is also found in sporadic PD. Thus, targeting α-synuclein clearance could be used as a drug-discovery strategy for PD treatment. Caffeic acid (CA) has shown neuroprotection in Alzheimer's disease or cerebral ischaemia; however, it is unclear whether CA confers neuroprotection in α-synuclein-induced PD models. Here we focus on whether and how A53T α-synuclein is affected by CA. We assessed the effect of CA on cell viability in SH-SY5Y cells overexpressing A53T α-synuclein. Pathway-related inhibitors were used to identify the autophagy mechanisms. Seven-month-old A53T α-synuclein transgenic mice (A53T Tg mice) received CA daily for eight consecutive weeks. Behaviour tests including the buried food pellet test, the pole test, the Rotarod test, open field analysis, and gait analysis were used to evaluate the neuroprotective effect of CA. Tyrosine hydroxylase and α-synuclein were assessed by immunohistochemistry or western blot in the substantia nigra (SN). We found that CA alleviated the cell damage induced by overexpressing A53T α-synuclein and that CA reduced A53T α-synuclein by activating the JNK/Bcl-2-mediated autophagy pathway. The efficacy of CA on A53T α-synuclein degradation was reversed by the autophagy inhibitor bafilomycin A1 and the JNK inhibitor SP600125. In A53T Tg mice, CA improved behavioural impairments, attenuated loss of dopaminergic neurons, enhanced autophagy and reduced α-synuclein in the SN. Thus, the results provide scientific evidence for the neuroprotective effect of CA in PD. Our work lays the foundation for CA clinical trials to treat PD in the future.