Nonalcoholic fatty liver disease (NAFLD) is one of the most common liver diseases which lacks ideal treatment options. Kaempferol and kaempferide, two natural flavonol compounds isolated from Hippophae rhamnoides L., were reported to exhibit a strong regulatory effect on lipid metabolism, for which the mechanism is largely unknown. In the present study, we investigated the effects of kaempferol and kaempferide on oleic acid (OA)-treated HepG2 cells, a widely used in vitro model of NAFLD. The results indicated an increased accumulation of lipid droplets and triacylglycerol (TG) by OA, which was attenuated by kaempferol and kaempferide (5, 10 and 20 μM). Western blot analysis demonstrated that kaempferol and kaempferide reduced expression of lipogenesis-related proteins, including sterol regulatory element-binding protein 1 (SREBP1), fatty acid synthase (FAS) and stearoyl-CoA desaturase 1 (SCD-1). Expression of peroxisome proliferator-activated receptor γ (PPARγ) and CCAAT enhancer binding proteins β (C/EBPβ), two adipogenic transcription factors, was also decreased by kaempferol and kaempferide treatment. In addition, western blot analysis also demonstrated that kaempferol and kaempferide reduced expression of heme oxygenase-1 (HO-1) and nuclear transcription factor-erythroid 2-related factor 2 (Nrf2). Molecular docking was performed to identify the direct molecular targets of kaempferol and kaempferide, and their binding to SCD-1, a critical regulator in lipid metabolism, was revealed. Taken together, our findings demonstrate that kaempferol and kaempferide could attenuate OA-induced lipid accumulation and oxidative stress in HepG2 cells, which might benefit the treatment of NAFLD.

The aim of the present study was to investigate the changes in lung histomorphology and oxidative stress, as well as the expression of interleukin (IL)‑17C and other inflammatory factors during acute mountain sickness (AMS) in male Sprague‑Dawley rats and to explore the underlying mechanism. Rats were randomly divided into a control group (0 h) and three hypoxia stress groups, exposed to low‑pressure oxygen storage at a simulated altitude of 6,000 m for 24, 48 and 72 h, respectively. Morphological changes in lung tissue were observed by hematoxylin and eosin staining under light microscopy and transmission electron microscopy. The expression of inflammatory factors IL‑17C, nuclear factor‑κB (NF‑κB), IL‑1β, IL‑6 and tumor necrosis factor‑α (TNF‑α) in lung tissue was assessed by RNA sequencing and verified by reverse transcription‑quantitative PCR (RT‑qPCR) and western blotting (WB). Superoxide dismutase (SOD) and glutathione peroxidase (GSH‑Px) enzyme activity and malondialdehyde (MDA) expression were also measured. Experimental groups were compared to the control group following 24, 48 and 72 h of hypoxic stress. Lung tissue suffered from different degrees of injury, and the damage was the most severe after 48 h of hypoxic stress. RNA sequencing data from the lung tissue of rats from each group suggested that the expression of IL‑17C, NF‑κB, IL‑1β, IL‑6, and TNF‑α increased significantly after hypoxic stress. RT‑qPCR and WB demonstrated that the expression of IL‑17C and NF‑κB increased significantly after hypoxia lasting 48 and 72 h. IL‑1β expression increased significantly after hypoxia stress lasting 24 and 48 h, and the expressions of TNF‑α and IL‑6 increased significantly after hypoxia stress lasting 24, 48 and 72 h (P<0.01). The enzyme activity of SOD and GSH‑Px decreased significantly after lasting 24, 48 and 72 h of hypoxia (P<0.01), and MDA increased significantly after hypoxic stress lasting 48 and 72 h (P<0.01). In conclusion, under hypoxic stress, rats quickly initiate oxidative stress and immune responses. However, with prolonged hypoxic stress time, excessive oxidative stress can further stimulate the immune system in vivo, and release a large quantity of inflammatory factors accumulating in the body. This, in turn, may lead to the occurrence of inflammatory storms and further damage the lung tissue resulting in AMS.

Pu, Xiaoyan, Xue Lin, Xianglan Duan, Junjie Wang, Jun Shang, Haixia Yun, and Zhi Chen. Oxidative and endoplasmic reticulum stress responses to chronic high-altitude exposure during the development of high-altitude pulmonary hypertension. High Alt Med Biol . 21:378–387, 2020. Objectives: To investigate the effect of endoplasmic reticulum (ER) stress during the development of high-altitude pulmonary hypertension (HAPH) after chronic high-altitude exposure, as well as the association between oxidative stress and ER stress. Methods: Forty male Sprague-Dawley rats were placed in a low-pressure chamber with a simulated altitude of 4,200 m for 0–28 days. Rats were chosen at random on days 0, 7, 14, and 28 of chronic high-altitude exposure and were examined for pulmonary arterial pressure, oxidative stress, apoptosis, and ER stress. Results: Chronic high-altitude exposure caused a continuous deterioration of pulmonary hypertension, which was accompanied by obvious apoptosis of alveolar epithelial cells and remodeling of pulmonary vessels. From day 7 of high-altitude exposure, although the activities of glutathione peroxidase and superoxide dismutase were gradually decreased, the generation of both malondialdehyde and reactive oxygen species was increased in a time-dependent manner. The protein expression of ER stress-related GRP78, PERK, IRE1α, ATF6, ATF4, CHOP, and caspase-12 in lung tissue was significantly upregulated from day 14 of high-altitude exposure. Further, the expression of caspase-12 in alveolar epithelial cells and vascular smooth muscle cells was also increased from day 14 of high-altitude exposure. Conclusions: Early high-altitude exposure first activates oxidative stress; then, it gradually activates ER stress. The activation of ER stress might promote the apoptosis of alveolar epithelial cells and the remodeling of pulmonary vessels by exacerbating the oxidative stress response during the development of HAPH after chronic high-altitude exposure.

The Qinghai–Tibet Plateau is one of the regions most strongly affected by climate change. The climate feedback of the distribution of plateau pika, a key species, is closely related to the trophic structure of the plateau ecosystem and the development of agriculture and animal husbandry on the plateau. In order to understand the impact of future climate change on the suitable distribution area of plateau pika, potential suitable distribution areas of Plateau pika were predicted using the MaxEnt model under three climate scenarios (SSP 1-2.6, SSP 2-4.5, and SSP 5-8.5) in the near term (2021–2040) and medium term (2041–2060). The predictions were found to be highly accurate with AUC values of 0.997 and 0.996 for the training and test sets. The main results are as follows: (1) The precipitation of the wettest month (BIO 16), mean diurnal range (BIO 2), slope, elevation, temperature seasonality (BIO 4), and annual mean temperature (BIO 1) were the main influencing factors. (2) In the historical period, the total suitable distribution area of Plateau pika in the Qinghai–Tibet Plateau accounted for 29.90% of the total area at approximately 74.74 × 10⁴ km², concentrated in the eastern and central areas of the Qinghai–Tibet Plateau. (3) The total suitable distribution area of pika exhibited an expansion trend under SSP 1-2.6 and SSP 2-4.5 in the near term (2021–2040), and the expansion area was concentrated in the eastern and central parts of the Qinghai–Tibet Plateau. The expansion area was the largest in Qinghai Province, followed by Sichuan Province and Tibet. In contrast, the suitable distribution area shrank in the Altun Mountains, Xinjiang. Under SSP 5-8.5 in the near term and all scenarios in the medium term (2041–2060), the suitable distribution area of Plateau pika decreased to different degrees. The shrinkage area was concentrated at the margin of the Qaidam Basin, central Tibet, and the Qilian Mountains in the east of Qinghai Province. (4) Plateau pika migrated toward the east or southeast on the Qinghai–Tibet Plateau under the three climate scenarios. Under most of the scenarios, the migration distance was longer in the medium term than in the near term.