[Role of PPARγ, a transcription factor in cardiovascular disease]

Traumatic Brain Injury-Mediated Neuroinflammation and Neurological Deficits are Improved by 8-Methoxypsoralen Through Modulating PPARγ/NF-κB Pathway

8-Methoxypsoralen (8-MOP) has anti-inflammatory, antioxidant and tissue-repairing abilities. Here, we probed the function and mechanism of 8-MOP in traumatic brain injury (TBI). The in-vivo TBI model was constructed in Sprague-Dawley (SD) rats using controlled cortical impact (CCI) surgery. In parallel, BV2 microglia and HT22 neurons were activated by lipopolysaccharide (LPS) to establish an in-vitro model. The modified neurological score (mNSS) and the Morris water maze experiment were employed to evaluate the rats' neurological functions. The rats' brain edema was assessed by the dry and wet method, and neuronal apoptosis in damaged brain tissues was monitored by terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling (TUNEL) and Nissl's staining. Immunohistochemistry (IHC) was applied to verify Iba1-microglial activation in brain lesions of rats. The expression of inflammatory cytokines in BV2 microglia and HT22 neurons in the injured lesion of TBI rats was examined by the enzyme-linked immunosorbent assay (ELISA). The levels of iNOS, COX2, TLR4, PPARγ, STAT3, and NF-κB in brain lesions, BV2 microglia and HT22 neurons were compared by Western blot. As a result, 8-MOP administration reduced inflammation and LPS-induced neuronal damage in BV2 microglia. In vivo, 8-MOP treatment relieved neurological deficits in TBI rats, improved cognitive, learning and motor functions and mitigated brain edema and neuroinflammation induced by TBI. Furthermore, LPS or TBI activated the NF-κB and STAT3 pathways and repressed the PPARγ expression. However, 8-MOP treatment attenuated NF-κB and STAT3 phosphorylation and elevated PPARγ levels. Hence, 8-MOP exerts neuroprotective and anti-inflammatory effects in TBI rats by modulating the PPARγ/NF-κB pathway.

Recent advancement on development of drug-induced macrophage polarization in control of human diseases

Macrophages, an important part of human immune system, possess a high plasticity and heterogeneity (macrophage polarization) as classically activated macrophages (M1) and alternatively activated macrophages (M2), which exert pro-inflammatory/anti-tumor and anti-inflammatory/pro-tumor effects, respectively. Thus, drug development in induction of macrophage polarization could be used to treat different human diseases. This review summarizes the recent advancement on modulation of macrophage polarization and its related molecular mechanisms induced by a number of agents. Research on the anti-inflammatory drugs to regulate the macrophage polarization accounts for a large proportion in the field and types of diseases investigated could include atherosclerosis, enteritis, nephritis, and the nervous system and skeletal diseases, while study of the anti-tumor agents to modify macrophage polarization is a novel area of research. Future study of the molecular mechanisms by which the different agents regulate the macrophage polarization could lead to an effective control of various human diseases, including inflammation and cancers.

WISP1 alleviates lipid deposition in macrophages via the PPARγ/CD36 pathway in the plaque formation of atherosclerosis

Lipid deposition in macrophages plays an important role in atherosclerosis. The WNT1-inducible signalling pathway protein 1(WISP1) can promote proliferation and migration of smooth muscle cells. Its expression is up-regulated in obesity, which is associated with atherosclerosis, but the effect of WISP1 on atherosclerosis remains unclear. Thus, the objective of our study was to elucidate the role of WISP and its mechanism of action in atherosclerosis via in vivo and in vitro experiments. In our experiment, ApoE-/- mice were divided into 5 groups: control, high-fat diet (HFD), null lentivirus (HFD + NC), lentivirus WISP1 (HFD + IvWISP1) and WISP1-shRNA (HFD + shWISP1). Oil Red O staining, immunofluorescence and immunohistochemistry of the aortic sinuses were conducted. Macrophages (RAW264.7 cell lines and peritoneal macrophages) were stimulated with 50 μg/mL oxidized low-density lipoprotein (ox-LDL); then, the reactive oxygen species (ROS) level was measured. Oil Red O staining and Dil-ox-LDL (ox-LDL with Dil dye) uptake measurements were used to test lipid deposition of peritoneal macrophages. WISP1, CD36, SR-A and PPARγ expression levels were measured via Western blotting and ELISA. The results showed that HFD mice had increased WISP1, CD36 and SR-A levels. The plaque lesion area increased when WISP1 was down-regulated, and lipid uptake and foam cell formation were inhibited when WISP1 was up-regulated. Treatment of RAW264.7 cell lines with ox-LDL increased WISP1 expression via activation of the Wnt5a/β-catenin pathway, whereas ROS inhibition reduced WISP1 expression. Moreover, WISP1 down-regulated CD36 and SR-A expression, and Oil Red O staining and Dil-ox-LDL uptake measurement showed that WISP1 down-regulated lipid deposition in macrophages. These results clearly demonstrate that WISP1 is activated by ox-LDL at high ROS levels and can alleviate lipid deposition in atherosclerosis through the PPARγ/CD36 pathway.