Targeting DUSP16/TAK1 signaling alleviates hepatic dyslipidemia and inflammation in high fat diet (HFD)-challenged mice through suppressing JNK MAPK.

Nonalcoholic fatty liver disease (NAFLD) is featured by hepatic steatosis, insulin resistance, lipid deposition and inflammation. However, the pathogenic mechanism of NAFLD is still poorly understood. Dual-specificity phosphatase 16 (DUSP16), a c-Jun N-terminal kinase-specific phosphatase, has been reported to negatively modulate the mitogen-activated protein kinases (MAPKs) signaling, and it has never been investigated in NAFLD progression. In the study, we identified that DUSP16 could directly interact with TAK1 in human hepatocytes. DUSP16 knockdown in the isolated primary hepatocytes stimulated by palmitate (PA) showed accelerated lipid deposition and inflammatory response, along with the exacerbated activation of c-Jun NH2-terminal kinase (JNK), Transforming growth factor ß (TGF-ß)-activated kinase (TAK1) and nuclear factor-κB (NF-κB) signaling pathways; however, the opposite results were detected in PA-treated hepatocytes with DUSP16 over-expression. The in vivo experiments confirmed that DUSP16 knockout significantly aggravated the metabolic disorder and insulin resistance in high fat diet (HFD)-challenged mice. In addition, HFD-provoked hepatic lipid accumulation and inflammation were further promoted in mice with DUSP16 knockout through the same molecular mechanism as detected in vitro. Herein, these findings demonstrated that DUSP16 could directly interact with TAK1 and negatively regulate JNK signaling to alleviate metabolic stress-induced hepatic steatosis, and thus could be considered as a promising new molecular target for NAFLD treatment.

iRhom2 deficiency relieves TNF-α associated hepatic dyslipidemia in long-term PM2.5-exposed mice.

Accumulating researches reported that particulate matter (PM2.5) is a risk factor for developing various diseases, including metabolic syndrome. Recently, inactive rhomboid protein 2 (iRhom2) was considered as a necessary modulator for shedding of tumor necrosis factor-α (TNF-α) in immune cells. TNF-α, a major pro-inflammatory cytokine, was linked to various pathogenesis of diseases, including dyslipidemia. Here, wild type (WT) and iRhom2-knockout (iRhom2-/-) mice were used to investigate the effects of iRhom2 on PM2.5-induced hepatic dyslipidemia. The hepatic histology, inflammatory response, glucose tolerance, serum parameters and gene expressions were analyzed. We found that long-term inhalation of PM2.5 resulted in hepatic steatosis. And a significant up-regulation of iRhom2 in liver tissues was observed, accompanied with elevated TNF-α, TNF-α converting enzyme (TACE), TNFα receptor (TNFR)2 and various inflammatory cytokines expressions. Additionally, PM2.5 treatment caused TG and TC accumulation in serum and liver, probably attributed to changes of genes modulating lipid metabolism. Intriguingly, hepatic injury and dyslipidemia were attenuated by iRhom2-/- in mice with PM2.5 challenge. In vitro, iRhom2-knockdwon reduced TNF-α expressions and its associated inflammatory cytokines in Kupffer cells, implying that liver-resident macrophages played an important role in regulating hepatic inflammation and lipid metabolism in cells treated with PM2.5. The findings indicated that long-term PM2.5 exposure caused hepatic steatosis and dyslipidemia through triggering inflammation, which was, at least partly, dependent on iRhom2/TNF-α pathway in liver-resident macrophages.

Expression profiles of glutathione S-transferase genes in larval midgut of Bombyx mori exposed to insect hormones.

Glutathione S-transferases (GSTs) are believed to play a role in the detoxification of xenobiotics, resistance to insect viruses and pesticides, intracellular transport, biosynthesis of hormones and protection against oxidative stress. In this study, we used quantitative real time RT-PCR to examine expression profiles of the silkworm Bombyx mori GST-Sigma (BmGSTS2) and GST-Delta (BmGSTD2) genes in the larval midgut of the silkworm after exposure to 2-hydroxyecdysone (20E) and juvenile hormone analog (JHA). In concentration-course study, 20E at higher concentrations (1.0 and 2.0 µg/µl) caused significant upregulation of BmGSTD2, and all concentrations (0.5-2.0 µg/µl) of 20E caused significant upregulation of BmGSTS2. However, JHA in all concentrations downregulated the expression of BmGSTD2 and BmGSTS2. When exposed to either 20E (2.0 µg/µl) or JHA (2.0 µg/µl) on the third day of the fifth instar, the silkworm had higher BmGSTD2 at later time points: 15, 18, and 24 h for 20E and 24 h for JHA. BmGSTS2 expression was downregulated within 24 h after exposure to JHA and showed a time-dependent response after exposure to 20E. We also did a stage-dependent study, in which JHA downregulated BmGSTD2 expression and upregulated BmGSTS2 expression significantly at both day 1 and day 3 of the fifth instar. 20E upregulated the expression of BmGSTD2 and BmGSTS2 at the two stages. These findings imply that hormones have an important role in the regulation of basal GST expression. However, further validation and field trials should be carried out on the regulatory elements relevant to BmGSTD2 and BmGSTS2 gene expression.

Juglanin protects against high fat diet-induced renal injury by suppressing inflammation and dyslipidemia via regulating NF-κB/HDAC3 signaling.

Obesity is an important factor implicated in chronic kidney disease (CKD). Juglanin (Jug) is a natural compound extracted from the crude Polygonumaviculare, showing anti-inflammatory and anti-diabetic effects. However, whether Jug has protective effects against obesity-induced renal injury, little has been investigated. Herein, we attempted to explore the potential of Jug in mediating obesity-induced kidney disease in high fat diet (HFD)-challenged mice. Our results suggested that chronic HFD feeding markedly increased the body weights of mice compared to the ones fed with normal chow diet (NCD), along with significant glucose intolerance and insulin resistance. However, these metabolic disorders induced by HFD were effectively alleviated by Jug treatments in a dose-dependent manner. Moreover, HFD-challenged mice showed apparent histopathological changes in renal tissues with significant collagen accumulation, which were attenuated by Jug supplementation. In addition, Jug treatment decreased the expression levels of kidney injury molecule-1 (KIM-1), while increased nephrin and podocin expression levels in kidney of HFD-challenged mice, improving the renal dysfunction. Furthermore, HFD led to lipid deposition in kidney samples of mice by enhancing abnormal lipid metabolism. In addition, HFD promoted the releases of circulating pro-inflammatory cytokines, and enhanced the renal inflammation by activating nuclear factor-kappa B/histone deacetylase 3 (NF-κB/HDAC3) signaling. HFD-induced dyslipidemia and inflammation were considerably abrogated by Jug administration in mice. The protective effects of Jug against renal injury were confirmed in palmitate (PA)-stimulated HK2 cells in vitro mainly through suppressing the nuclear translocation of NF-κB and HDAC3, repressing inflammation and lipid accumulation eventually. Hence, Jug could ameliorate HFD-induced kidney injury mainly through blocking the NF-κB/HDAC3 nuclear translocation.

Dysfunctional Rhbdf2 of proopiomelanocortin mitigates ambient particulate matter exposure-induced neurological injury and neuron loss by antagonizing oxidative stress and inflammatory reaction.

Ambient particulate matter (PM2.5)-induced metabolic syndromes is a critical contributor to the pathological processes of neurological diseases, but the underlying molecular mechanisms remain poorly understood. The rhomboid 5 homolog 2 (Rhbdf2), an essential regulator in the production of TNF-α, has recently been confirmed to exhibit a key role in regulating inflammation-associated diseases. Thus, we examined whether Rhbdf2 contributes to hypothalamic inflammation via NF-κB associated inflammation activation in long-term PM2.5-exposed mice. Specifically, proopiomelanocortin-specific Rhbdf2 deficiency (Rhbdf2Pomc) and corresponding littermates control mice were used for the current study. After 24 weeks of PM2.5 inhalation, systemic-metabolism disorder was confirmed in WT mice in terms of impaired glucose tolerance, increased insulin resistance, and high blood pressure. Markedly, PM2.5-treated Rhbdf2Pomc mice displayed a significantly opposite trend in these parameters compared with those of the controls group. We next confirmed hypothalamic injury accompanied by abnormal POMC neurons loss, as indicated by increased inflammatory cytokines, chemokines, and oxidative-stress levels and decreased antioxidant activity. These results were further supported by blood routine examination. In summary, our findings suggest that Rhbdf2 plays an important role in exacerbating PM2.5-stimulated POMC neurons loss associated hypothalamic injury, thus providing a possible target for blocking pathological development of air pollution-associated diseases.

Endoplasmic reticulum stress-induced iRhom2 up-regulation promotes macrophage-regulated cardiac inflammation and lipid deposition in high fat diet (HFD)-challenged mice: Intervention of fisetin and metformin.

Endoplasmic reticulum stress (ERS) has been implicated in obesity-associated cardiac remodeling and dysfunction. Inactive rhomboid protein 2 (iRhom2), also known as Rhbdf2, is an inactive member of the rhomboid intramembrane proteinase family, playing an essential role in regulating inflammation. Nevertheless, the role of ERS-meditated iRhom2 pathway in metabolic stress-induced cardiomyopathy remains unknown. In the study, we showed that 4-PBA, as an essential ERS inhibitor, significantly alleviated high fat diet (HFD)-induced metabolic disorder and cardiac dysfunction in mice. Additionally, lipid deposition in heart tissues was prevented by 4-PBA in HFD-challenged mice. Moreover, 4-PBA blunted the expression of iRhom2, TACE, TNFR2 and phosphorylated NF-κB to prevent HFD-induced expression of inflammatory factors. Further, 4-PBA restrained HFD-triggered oxidative stress by promoting Nrf-2 signaling. Importantly, 4-PBA markedly suppressed cardiac ERS in HFD mice. The anti-inflammation, anti-ERS and anti-oxidant effects of 4-PBA were verified in palmitate (PAL)-incubated macrophages and cardiomyocytes. In addition, promoting ERS could obviously enhance iRhom2 signaling in vitro. Intriguingly, our data demonstrated that PAL-induced iRhom2 up-regulation apparently promoted macrophage to generate inflammatory factors that could promote cardiomyocyte inflammation and lipid accumulation. Finally, interventions by adding fisetin or metformin significantly abrogated metabolic stress-induced cardiomyopathy through the mechanisms mentioned above. In conclusion, this study provided a novel mechanism for metabolic stress-induced cardiomyopathy pathogenesis. Therapeutic strategy to restrain ROS/ERS/iRhom2 signaling pathway could be developed to prevent myocardial inflammation and lipid deposition, consequently alleviating obesity-induced cardiomyopathy.

Prolonged PM2.5 exposure elevates risk of oxidative stress-driven nonalcoholic fatty liver disease by triggering increase of dyslipidemia.

An increasing number of studies have shown that air pollution containing particulate matter (PM) ≤ 2.5 µm (PM2.5) plays a significant role in the development of metabolic disorder and other chronic diseases. Inflammation and oxidative stress caused by metabolic syndrome are widely determined to be critical factors in the development of nonalcoholic fatty liver disease (NAFLD) pathogenesis. However, there is no direct evidence of this, and the underlying molecular mechanism is still not fully understood. In this study, we investigated the role of inflammation and oxidative stress caused by prolonged PM2.5 exposure in dyslipidemia-associated chronic hepatic injury, and further determined whether an increase in hepatic inflammation and oxidative stress promoted lipid accumulation in the liver, ultimately increasing the risk of NAFLD. Therefore, we studied changes in indicators of metabolic disorder and in symbolic indices of NAFLD. We confirmed increases in insulin resistance, glucose tolerance, peripheral inflammation and dysarteriotony in PM2.5-induced mice. Oxidative stress and inflammatory response in the liver caused by PM2.5 inhalation contributed to abnormal hepatic function, further promoting lipid accumulation in the liver. Moreover, we observed inhibition of oxidative stress and inflammatory response by pyrrolidine dithiocarbamate (PDTC) and N-acetyl-L-cysteine (NAC) in vitro, suggesting that oxidative stress and inflammatory in liver cells aggravated by PM2.5 contributed to hepatic injury by altering normal lipid metabolism. These results indicate a new goal for preventing and treating air pollution-induced diseases: suppression of oxidative stress and inflammatory response.

Multicombination Approach Suppresses Listeria monocytogenes-Induced Septicemia-Associated Acute Hepatic Failure: The Role of iRhom2 Signaling.

The mortality rate of acute liver failure significantly increases due to fatal septicemia. Inactive rhomboid protein 2 (iRhom2) is an essential regulator of shedding TNF-α by trafficking with TNF-α converting enzyme (TACE). Fisetin, a flavonoid present in various fruits and plants, possesses anti-oxidative stress and anti-inflammatory activities. Here, multi-combination nanoparticles Fe@Au conjugated with fisetin, iRhom2 small interfering RNA (siRNA), and TNF-α inhibitor (FN) are prepared to examine their effects on fatal septicemia-associated hepatic failure induced by Listeria monocytogenes (LM) in mice and to reveal the underlying mechanisms. After LM infection, upregulation of glutamic-oxalacetic transaminease, glutamic-pyruvic transaminase, alkaline phosphatase, TNF-α, malondialdehyde, H2 O2 , and O2- is observedcompared to FN-treated mice. The iRhom2/TACE/TNF-α signals are enhanced in vivo and in vitro, resulting in oxidative stress, which is especially associated with the activation of kupffer cells and other macrophages. Decrease in Nrf2 activation and increase of inflammation-associated regulators are also noted in vivo and in vitro. Furthermore, overexpression of TNF-α derived from macrophages aggravates hepatic failure. Inversely, the processes above are restored by FN nanoparticles through the regulation of the iRhom2/TACE/TNF-α axis and Nrf2 activation. These findings suggest that FN may be a potential approach to protect against bacterial septicemia-related diseases by targeting iRhom2.

Activated iRhom2 drives prolonged PM2.5 exposure-triggered renal injury in Nrf2-defective mice.

Research suggests that particulate matter (PM2.5) is a predisposing factor for metabolic syndrome-related systemic inflammation and oxidative stress injury. TNF-α as a major pro-inflammatory cytokine was confirmed to participate in various diseases. Inactive rhomboid protein 2 (iRhom2) was recently determined as a necessary regulator for shedding of TNF-α in immune cells. Importantly, kidney-resident macrophages are critical to inflammation-associated chronic renal injury. Podocyte injury can be induced by stimulants and give rise to nephritis, but how iRhom2 contributes to PM2.5-induced renal injury is unclear. Thus, we studied whether PM2.5 causes renal injury and characterized iRhom2 with respect to TNF-α release in mice macrophages and renal tissues in long-term PM2.5-exposed mouse models. After long-term PM2.5 exposures, renal injury was confirmed via inflammatory cytokine, chemokine expression, and reduced antioxidant activity. Patients with kidney-related diseases had increased TNF-α, which may contribute to renal injury. We observed up-regulation of serum creatinine, serum urea nitrogen, kidney injury molecule 1, uric acid, TNF-α, MDA, H2O2, and O2- in PM2.5-treated mice, which was greater than that found in Nrf2-/- mice. Meanwhile, increases in metabolic disorder-associated indicators were involved in PM2.5-induced nephritis. In vitro, kidney-resident macrophages were observed to be critical to renal inflammatory infiltration and function loss via regulation of iRhom2/TACE/TNF-α signaling, and suppression of Nrf2-associated anti-oxidant response. PM2.5 exposure led to renal injury partly by inflammation-mediated podocyte injury. Reduced SOD1, SOD2, Nrf2 activation, and increased XO, NF-κB activity, TACE, iNOS, IL-1ß, TNF-α, IL-6, MIP-1α, Emr-1, MCP-1, and Cxcr4, were also noted. Long-term PM2.5 exposure causes chronic renal injury by up-regulation of iRhom2/TACE/TNF-α axis in kidney-resident macrophages. Overexpression of TNF-α derived from macrophages causes podocyte injury and kidney function loss. Thus, PM2.5 toxicities are related to exposure duration and iRhom2 may be a potential therapeutic renal target.