Effect of Phospholipid Transfer Protein on Cigarette Smoke Extract-Induced IL-8 Production in Human Pulmonary Epithelial Cells

Andrographolide attenuates oxidative stress injury in cigarette smoke extract exposed macrophages through inhibiting SIRT1/ERK signaling

Andrographolide (AG), an ingredient extracted from traditional Chinese herbal medicine Andrographis paniculata, has been demonstrated to have potent anti-inflammatory and anti-oxidative stress properties. The purpose of this study was to investigate whether and how AG attenuated CSE-induced mitochondrial dysfunction, inflammation and oxidative stress in RAW 264.7 cells (a mouse macrophages line). The results showed that AG significantly reduced CSE-induced upregulation of pro-inflammatory cytokines (i.e., TNF-α and IL-1β) in the RAW 264.7 cells. AG inhibited CSE-induced production of reactive oxygen species (ROS) and prevented the reduction of superoxide dismutase (SOD) and glutathione/oxidized glutathione (GSH/GSSG) ratio, indicating the anti-oxidative stress effects of AG in macrophages. AG also improved mitochondrial function and mitochondrial membrane potential. In addition, AG inhibited CSE-induced increase of heme oxygenase (HO)-1, matrix metalloproteinase (MMP)-9 and MMP-12. Moreover, AG increased SIRT1 transcription and expression, suggesting AG inhibits mitochondrial dysfunction, inflammation and oxidative stress via a SIRT1 dependent signaling. We also demonstrated that AG inhibited CSE-induced ERK phosphorylation, and treatment with PD980589, a ERK inhibitor, reversed CSE-induced inflammation and oxidative stress. These results indicated that AG may prevent COPD via the inhibition of SIRT1/ERK signaling pathway, and subsequently inhibition of mitochondrial dysfunction, inflammation, and oxidative stress in macrophages.

Deletion of plasma Phospholipid Transfer Protein (PLTP) increases microglial phagocytosis and reduces cerebral amyloid-β deposition in the J20 mouse model of Alzheimer's disease

Plasma phospholipid transfer protein (PLTP) binds and transfers a number of amphipathic compounds, including phospholipids, cholesterol, diacylglycerides, tocopherols and lipopolysaccharides. PLTP functions are relevant for many pathophysiological alterations involved in neurodegenerative disorders (especially lipid metabolism, redox status, and immune reactions), and a significant increase in brain PLTP levels was observed in patients with Alzheimer's disease (AD) compared to controls. To date, it has not been reported whether PLTP can modulate the formation of amyloid plaques, i.e. one of the major histopathological hallmarks of AD.

We thus assessed the role of PLTP in the AD context by breeding PLTP-deficient mice with an established model of AD, the J20 mice. A phenotypic characterization of the amyloid pathology was conducted in J20 mice expressing or not PLTP. We showed that PLTP deletion is associated with a significant reduction of cerebral Aβ deposits and astrogliosis, which can be explained at least in part by a rise of Aβ clearance through an increase in the microglial phagocytic activity and the expression of the Aβ-degrading enzyme neprilysin.

PLTP arises as a negative determinant of plaque clearance and over the lifespan, elevated PLTP activity could lead to a higher Aβ load in the brain.