Impact of TonEBP in myeloid cells on neuroinflammation and obesity-induced insulin resistance

Department of Biological SciencesTonicity-responsive enhancer-binding protein (TonEBP, also called NFAT5) is stress protein that mediates cellular responses via pleiotropic actions. In stress conditions, TonEBP regulates transcription of many genes using different mechanisms: transcription factor, transcriptional suppressor or cofactor. During my degree, I investigated impact of TonEBP in myeloid cells on neuroinflammation and obesity-induced insulin resistance. Inflammation is biological response to harmful stimuli but also largely considered as contributor to disease development. Neuroinflammation is related with neurodegenerative disease showing memory loss and cognitive deficits. In the brain, Inflammatory stimulus prime microglia cell. This results in a constant production of inflammatory cytokines and chemokines (NO, TNF-??, and IL-1??) by these cellsin turn, the cytokines and chemokines maintain activation of the primed cells. This process results in a vicious circle, and finally causing neuron loss and neurodegeneration. Transcription factors NF-??B and AP-1 are key mediators of inflammation associated with many inflammatory diseases including AD. Here we report that TonEBP promotes neuroinflammation and neuronal cell death through microglial activation. In the microglia cell line BV2, TonEBP deficiency reduced LPS-induced expression and secretion of pro-inflammatory cytokines TNF-?? and IL-1?? in association with decreased activity of both NF-??B and AP-1. This was due to a reduced assembly of pro-inflammatory transcriptional complex which consisted of TonEBP, NF-??B, AP-1, and p300. As expected, myeloid-specific TonEBP deletion blunted the LPS-induced microglia activation and neuroinflammation. Cerulenin, a small molecule which disrupted the assembly of the pro-inflammatory transcriptional complex, suppressed the LPS-induced activation of microglia and memory loss in association with alleviation of neuronal cell death. The incidence of obesity worldwide has increased drastically during recent decades. Obesity is associated with increased risk of insulin resistance, type 2 diabetes. Visceral adipose tissue expansion is associated with chronic low-grade inflammation and metabolic dysfunction characterized by progressive accumulation of immune cells. Here, we show that myeloid cell-specific TonEBP depletion reduced inflammation and insulin resistance in mice with high-fat diet-induced obesity, but did not affect adiposity. This phenotype was associated with a reduced accumulation and a reduced M1-like/M2-like ratio of macrophagesdecreased expression of inflammatory factors related to insulin resistanceand enhanced insulin sensitivity in epididymal white adipose tissue and the liver. TonEBP expression in macrophages was elevated by concentrations of palmitate and gut-derived endotoxin found in obese individuals, and Sp1 was identified as a central regulator of TonEBP induction. TonEBP in macrophages promotes obesity-associated systemic insulin resistance and inflammation, and downregulation of TonEBP may induce a healthy metabolic state during obesity. In conclusion, TonEBP in myeloid cells is a major factor in the immune response that accelerates disease development. Thus, TonEBP is a promising therapeutic target for neuroinflammation and obesity-induced insulin resistance.ope

Microglial TonEBP mediates LPS-induced inflammation and memory loss as transcriptional cofactor for NF-kappa B and AP-1

Background Microglia are brain-resident myeloid cells involved in the innate immune response and a variety of neurodegenerative diseases. In macrophages, TonEBP is a transcriptional cofactor of NF-kappa B which stimulates the transcription of pro-inflammatory genes in response to LPS. Here, we examined the role of microglial TonEBP. Methods We used microglial cell line, BV2 cells. TonEBP was knocked down using lentiviral transduction of shRNA. In animals, TonEBP was deleted from myeloid cells using a line of mouse with floxed TonEBP. Cerulenin was used to block the NF-kappa B cofactor function of TonEBP. Results TonEBP deficiency blocked the LPS-induced expression of pro-inflammatory cytokines and enzymes in association with decreased activity of NF-kappa B in BV2 cells. We found that there was also a decreased activity of AP-1 and that TonEBP was a transcriptional cofactor of AP-1 as well as NF-kappa B. Interestingly, we found that myeloid-specific TonEBP deletion blocked the LPS-induced microglia activation and subsequent neuronal cell death and memory loss. Cerulenin disrupted the assembly of the TonEBP/NF-kappa B/AP-1/p300 complex and suppressed the LPS-induced microglial activation and the neuronal damages in animals. Conclusions TonEBP is a key mediator of microglial activation and neuroinflammation relevant to neuronal damage. Cerulenin is an effective blocker of the TonEBP actions

Effect of the glyceryl monooleate-based lyotropic phases on skin permeation using in vitro diffusion and skin imaging

AbstractGlyceryl monooleate (GMO) is a polar lipid that can exist in various liquid crystalline phases in the presence of different amounts of water. It is regarded as a permeation enhancer due to its amphiphilic property. Various phases of GMO/solvent system containing sodium fluorescein were prepared to compare permeability using confocal laser scanning microscopy (CLSM). GMO was melted in a vial in a water bath heated to 45 °C. Propylene glycol and hexanediol were homogeneously dissolved in the melted GMO. Sodium fluorescein in aqueous solution was diluted to various ratios and thoroughly mixed by an ultrasonic homogenizer. Each GMO/Solvent system with fluorescein was applied onto the epidermal side of excised pig skin and incubated overnight. CLSM was performed to observe how the GMO/solvent system in its different phases affect skin permeability. Cubic and lamellar phase formulations enhanced the fluorescein permeation through the stratum corneum. A solution system had the weakest permeability compared to the other two phases. Due to the amphiphilic nature of GMO, cubic and lamellar phases might reduce the barrier function of stratum corneum which was observed by CLSM as fluorescein accumulated in the dermis. Based on the results, the glyceryl monooleate lyotropic mixtures could be applied to enhance skin permeation in various topical and transdermal formulations

Selective Regional Loss of Cortical Synapses Lacking Presynaptic Mitochondria in the 5xFAD Mouse Model

Synaptic loss in Alzheimer's disease (AD) is strongly correlated with cognitive impairment. Accumulating evidence indicates that amyloid pathology leads to synaptic degeneration and mitochondrial damage in AD. However, it remains unclear whether synapses and presynaptic mitochondria are differentially affected in various cortical regions of the AD brain at the ultrastructural level. Using serial block-face scanning electron microscopy, we assessed synaptic structures in the medial prefrontal cortex (mPFC) and primary visual cortex (V1) of the 5xFAD mouse model of AD. At 6 months of age, 5xFAD mice exhibited significantly elevated levels of amyloid deposition in layer 2/3 of the mPFC but not V1. Accordingly, three-dimensional reconstruction of synaptic connectivity revealed a significant reduction in excitatory synaptic density in layer 2 of the mPFC, but not V1, of male transgenic mice. Notably, the density of synapses lacking presynaptic mitochondria was selectively decreased in the mPFC of 5xFAD mice, with no change in the density of mitochondria-containing synapses. Further classification of spines into shape categories confirmed a preferential loss of thin spines whose presynaptic boutons were largely devoid of mitochondria in the 5xFAD mPFC. Furthermore, the number of mitochondria per bouton in spared mitochondria-containing boutons was reduced in the mPFC, but not V1, of 5xFAD mice. Collectively, these results highlight region-specific vulnerability of cortical synapses to amyloid deposition and suggest that the presence of presynaptic mitochondria may affect synaptic degeneration in AD.1

Prognosis according to the timing of percutaneous coronary intervention in non-ST segment elevation myocardial infarction, based on the Korean Acute Myocardial Infarction Registry (KAMIR)

Background: Patients with acute coronary syndrome without ST-segment elevation (ACS- -NSTE) are at risk for adverse cardiac events. Based on data in the Korean Acute Myocardial Infarction Registry (KAMIR), we analyzed the prognosis according to the timing of percutaneous coronary intervention (PCI) in patients with NSTEMI in Korea. Methods and results: 2,455 patients with NSTEMI in KAMIR were classified according to the time interval from the onset of cardiac symptoms to PCI. Patients in Group I underwent PCI within 24 hours of the onset of symptoms; in Group II between 24 and 48 hours; and in Group III after 48 hours. Major adverse cardiac events (MACEs) are defined as cardiac death, non-cardiac death, myocardial infarction, revascularization and coronary-artery bypass graft surgery. The MACEs were compared between groups. Of the 2,455 patients, 743 (30.2%) were assigned to Group I, 583 (23.7%) to Group II, and 1,129 (45.9%) to Group III. The total incidence of MACEs was higher in Group I than Group III, and similar between Groups I and II (Group I: 15.1%, Group II: 14.4%, Group III: 11.6%, p = 0.053). The incidence of MACEs in the intermediate TIMI risk score group had decreased as the intervention time was delayed. Conclusions: The prognosis according to the timing of PCI in patients with NSTEMI was similar based on the data in KAMIR. TIMI risk score was related to a high incidence of MACEs. (Cardiol J 2011; 18, 4: 421–429