Caveolin-1 protects against liver damage exacerbated by acetaminophen in non-alcoholic fatty liver disease by inhibiting the ERK/HIF-1α pathway.

Acetaminophen (APAP) is a common antipyretic and analgesic drug that can cause long-term liver damage after an overdose. Non-alcoholic fatty liver disease (NAFLD) increases susceptibility to APAP. In NAFLD, excessive accumulation of lipids leads to an abnormal increase in hypoxia-inducible factor-1α (HIF-1α). Caveolin-1 (CAV1) may protect against NAFLD by inhibiting HIF-1α. This research aimed to determine whether CAV1 could attenuate APAP-exacerbated liver injury in NAFLD by inhibiting oxidative stress involving HIF-1α. In this study, 7-week-old C57BL/6 mice were fed a high-fat diet (HFD) for eight weeks, followed by the instillation of APAP. Levels of oxidative stress and liver lipid deposition were determined, and p-ERK1/2 and HIF-1α protein expression were measured by the Western blot (WB) method. In the APAP-treated group, the level of CAV1 was decreased, while the levels of HIF-1α and reactive oxygen species (ROS) were significantly increased. AML12 cells were treated with a mixture of palmitic acid (PA) and oleic acid (OA) (1:2 mix) for 48 h, and APAP was added for the last 24 h. Overexpression of CAV1 in AML12 cells significantly inhibited the expression of ROS and HIF-1α. And the results of immunofluorescence after treatment with CAV1-SiRNA showed that the HIF-1α levels were significantly increased in mitochondria. In conclusion, our experimental results suggest that CAV1 has a protective function in the fatty liver based on preventing oxidative stress, which involves HIF-1α. Thus, upregulation of CAV1 may attenuate APAP-exacerbated liver injury in NAFLD.

Caveolin-1 alleviates acetaminophen-induced vascular oxidative stress and inflammation in non-alcoholic fatty liver disease.

Acetaminophen (APAP) is one of the most widely used drugs in the world. The literature shows that excessive or long-term use of APAP can lead to increased cardiovascular dysfunction. An acute increase in angiotensin Ⅱ (Ang Ⅱ) caused by APAP use in fatty liver disease may increase the risk and severity of vascular injury. However, the underlying mechanism remains unclear. Caveolin-1 (CAV1) is a broad-spectrum kinase inhibitor that significantly determines endothelial function. This study aimed to observe the effects of APAP on the vasculature in non-alcoholic fatty liver disease (NAFLD) and to determine whether CAV1 could alleviate vascular oxidative stress and inflammation by targeting Ang Ⅱ or its downstream pathways. In this study, 7-week-old C57BL/6 male mice (18-20 g) were administered APAP by gavage after eight weeks of a high-fat diet. Any resulting vascular oxidative stress and inflammation were assessed. Levels of Ang Ⅱ, CAV1, and other related proteins were measured using ELISA and western blotting. In APAP-treated NAFLD mice, CAV1 expression was downregulated and Ang Ⅱ expression was upregulated compared to normal APAP-treated mice. In vitro, HUVECs were incubated with Ang Ⅱ (300 nM) for 48 h. Overexpression of CAV1 in HUVECs attenuated Ang Ⅱ-induced oxidative stress and inflammation and downregulated the expression of Protein kinase C (PKC) and p-P38/P38. After intervention with CAV1-siRNA, immunofluorescence results showed that the fluorescence intensity of PKC on mitochondria was further increased, and flow cytometry results showed that the mitochondrial membrane potential increased. PKC inhibitors alleviated Ang Ⅱ-induced endothelial injury. In conclusion, our findings confirmed that CAV1 exerts a protective effect against vascular injury by inhibiting oxidative stress and inflammation through the PKC/MAPK pathway. Therefore, restoration of CAV1 may have clinical benefits in reducing APAP-induced vascular damage in NAFLD patients.

Caveolin-1 ameliorates acetaminophen-aggravated inflammatory damage and lipid deposition in non-alcoholic fatty liver disease via the ROS/TXNIP/NLRP3 pathway.

The overuse of acetaminophen (APAP) may cause more severe hepatotoxicity in patients with non-alcoholic fatty liver disease (NAFLD). Caveolin-1 (CAV1), is an essential regulator of metabolic function, which can alleviate liver damage by scavenging reactive oxygen species (ROS). Evidence suggests that the NOD-like receptor family pyrin domain-containing 3 (NLRP3) -mediated pyroptosis is involved in the development of NAFLD. Moreover, thioredoxin-interactive protein (TXNIP) activation is a key event linking ROS to NLRP3 inflammasome. However, whether CAV1 alleviates APAP-aggravated hepatotoxicity in NAFLD via the ROS/TXNIP/NLRP3 pathway remains unclear. An in vivo fatty liver model was established by feeding mice a high-fat diet for 56 days. Additionally, using in vitro approach, AML-12 cells were incubated with free fatty acids for 48 h and APAP was added during the last 24 h. We found that the overuse of APAP in NAFLD not only induced oxidative stress, but also increased TXNIP expression, NLRP3-mediated pyroptosis, and lipid deposition. In addition to inhibiting ROS generation and lipid deposition, overexpression of CAV1 reduced the elevated levels of TXNIP expression and NLRP3-mediated pyroptosis. However, the effect of CAV1 on TXNIP expression, NLRP3-mediated pyroptosis, and lipid deposition was reversed by CAV1 small interfering RNA (siRNA) intervention. Finally, N-acetyl cysteine (NAC) treatment reduced CAV1 siRNA-mediated changes in TXNIP expression and NLRP3-mediated pyroptosis levels. These results demonstrate that the inhibitory effect of CAV1 on NLRP3-mediated pyroptosis may be mediated through the ROS/TXNIP axis. Moreover, the current study provides novel mechanistic insights into the protective effects of CAV1 on APAP-aggravated hepatotoxicity in NAFLD.

Caveolin-1 Alleviates Acetaminophen-Induced Hepatotoxicity in Alcoholic Fatty Liver Disease by Regulating the Ang II/EGFR/ERK Axis.

Acetaminophen (APAP) is a widely used antipyretic analgesic which can lead to acute liver failure after overdoses. Chronic alcoholic fatty liver disease (AFLD) appears to enhance the risk and severity of APAP-induced liver injury, and the level of angiotensin II (Ang II) increased sharply at the same time. However, the underlying mechanisms remain unclear. Caveolin-1 (CAV1) has been proven to have a protective effect on AFLD. This study aimed to examine whether CAV1 can protect the APAP-induced hepatotoxicity of AFLD by affecting Ang II or its related targets. In vivo, the AFLD model was established according to the chronic-plus-binge ethanol model. Liver injury and hepatic lipid accumulation level were determined. The levels of Angiotensin converting enzyme 2 (ACE2), Ang II, CAV1, and other relevant proteins were evaluated by western blotting. In vitro, L02 cells were treated with alcohol and oleic acid mixture and APAP. CAV1 and ACE2 expression was downregulated in APAP-treated AFLD mice compared to APAP-treated mice. The overexpression of CAV1 in mice and L02 cells alleviated APAP-induced hepatotoxicity in AFLD and downregulated Ang II, p-EGFR/EGFR and P-ERK/ERK expression. Immunofluorescence experiments revealed interactions between CAV1, Ang II, and EGFR. The application of losartan (an Ang II receptor antagonist) and PD98059 (an ERK1/2 inhibitor) alleviated APAP-induced hepatotoxicity in AFLD. In conclusion, our findings verified that CAV1 alleviates APAP-aggravated hepatotoxicity in AFLD by downregulating the Ang II /EGFR/ERK axis, which could be a novel therapeutic target for its prevention or treatment.

[Effect of psoralen plus longwave UVA inducing HL-60 cells apoptosis].

The aim of this study was to investigate the effects of the traditional Chinese medicine psoralen (PSO) plus long wave ultraviolet A (PUVA) on apoptosis in HL-60 leukemia cells and its mechanism. The effect of PUVA on HL-60 cell growth was assayed by MTT method and the changes of ultrastructure of cells were observed by electron microscopy. The apoptosis ratios, changes of mitochondrial membrane potential, expression of Fas and FasL protein and Fas and FasL mRNA were detected by FCM and fluorescent quantitation RT-PCR respectively. The expression of Caspase 8 and Caspase 3 protein were detected by immunocytochemistry (ICC). The results showed that the growth of HL-60 cells were inhibited by PUVA in time-and concentration-dependent manner through inducing cell apoptosis. When the irradiation time of long wave ultraviolet A lasted 15 minutes and the concentration of PSO was 80 microg/ml, the inhibition of HL-60 cell proliferation and apoptosis ratios reached the peak. There were obvious apoptotic ultrastructure changes and decrease of mitochondrial membrane potential in HL-60 cells after treatment with PUVA. The expression of Fas mRAN increased and expression of FasL mRNA decreased after treating with PUVA for 4 hours, and the same results of Fas, FasL expression on protein level were obtained also after treating with PUVA for 24 hours. The expression of caspase 8 and caspase 3 protein enhanced and reached the peak after treating with PUVA for 8 hours. It is concluded that the PUVA can inhibit the growth of HL-60 cells and induce apoptosis of these cells. The possible mechanism is supposed to be up-regulating Fas, down-regulating FasL levels and then activating the levels of caspase 8 and caspase 3. The decreasing of mitochondrial membrane potential may be involved in this process probably.