M2 microglia-derived exosomes promote vascular remodeling in diabetic retinopathy.

Diabetic retinopathy (DR) is a vision-threatening diabetic complication that is characterized by microvasculature impairment and immune dysfunction. The present study demonstrated that M2 microglia intensively participated in retinal microangiopathy in human diabetic proliferative membranes, mice retinas, retinas of mice with oxygen-induced retinopathy (OIR) mice, and retinas of streptozotocin-induced DR mice. Further in vivo and in vitro experiments showed that exosomes derived from M2 polarized microglia (M2-exo) could reduce pericyte apoptosis and promote endothelial cell proliferation, thereby promoting vascular remodeling and reducing vascular leakage from the diabetic retina. These effects were further enhanced by M2-exo that facilitated M2 polarization of retinal microglia. Collectively, the study demonstrated the capability of M2-exo to induce retinal microvascular remodeling, which may provide a new therapeutic strategy for the treatment of DR.

Human lens epithelial-secreted exosomes attenuate ocular angiogenesis via inhibiting microglial activation.

The lens is an avascular tissue, where epithelial cells (LECs) are the primary living cells. The role of LECs-derived exosomes (LEC-exos) is largely unknown. In our study, we determined the anti-angiogenic role of LEC-exos, manifested as regressed retinal neovascularization (NV) using the oxygen-induced retinopathy (OIR), and reduced choroidal NV size and pathological vascular leakage using the laser-induced choroidal neovascularization (laser-induced CNV). Furthermore, the activation and accumulation of microglia were also restricted by LEC-exos. Based on Luminex multiplex assays, the expressions of chemokines such as SCYB16/CXCL16, MCP-1/CCL2, I-TAC/CXCL11, and MIP 3beta/CCL19 were decreased after treatment with LEC-exos. Transwell assays showed that LEC-exos restricted the migration of the mouse microglia cell line (BV2 cells). After incubation with LEC-exos-treated BV2 cells, human umbilical vein endothelial cells (hUVECs) were collected for further evaluation using tube formation, Transwell assays, and 5-ethynyl-2'-deoxyuridine (EDU) assays. Using in vitro experiments, the pro-angiogenic effect of microglia was restricted by LEC-exos. Hence, it was investigated that LEC-exos attenuated ocular NV, which might attribute to the inhibition of microglial activation and accumulation.

Effects of grazing and nitrogen application on greenhouse gas emissions in alpine meadow.

Overgrazing and injudicious nitrogen applications have increased emissions of greenhouse gases from grassland ecosystems. To explore the effects and potential mechanisms of grazing, nitrogen application, and their interaction with greenhouse gas (GHG) emissions, field experiments were conducted on the Qinghai-Tibet Plateau for three consecutive years. Alpine meadow plots were subjected to light (8 sheep ha-1) and heavy (16 sheep ha-1) stocking rates, with or without ammonium nitrate (NH4NO3) (90 kg N ha-1 yr-1) treatment to simulate soil nitrogen deposition. During early warm growth season (May-June), peak growth season (July-September), and early cold season (October-November), static-chamber gas chromatography was used to analyze the soil's greenhouse gas emissions (CO2, N2O, and CH4). Results indicated that light stocking rate (LG) led to an increase in cumulative CO2 and N2O emissions, while also promoting CH4 uptake. Conversely, heavy stocking rate (HG) produced contrasting outcomes. Additionally, nitrogen applications significantly increased the short-term CO2 and N2O fluxes peaks. Combined treatment of nitrogen application and light stocking rate (LG + N) resulted in increased CO2 and N2O emissions while decreased CH4 uptake, consequently leading to a significant increase in global warming potential. According to the structural equation model, we discovered that nitrogen application and grazing affected GHG fluxes both directly and indirectly through their impact on the environmental factors. Our findings suggest that in the context of increasing nitrogen deposition in the Qinghai-Tibet Plateau, a moderate increase in stocking rate is more effective than reducing grazing intensity for mitigating global warming potential in alpine meadow.

Pharmacokinetics, tissue distribution and plasma protein binding rate of palmatine following intragastric and intravenous administration in rats using liquid chromatography tandem mass spectrometry.

Palmatine is a natural isoquinoline alkaloid widely found in traditional Chinese medicines. In this study, a simple, sensitive and rapid ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) method was developed and validated for the quantification of palmatine in the plasma and tissue samples in rats. Sample preparation involved a simple protein precipitation extraction technique using acetonitrile as the precipitating solvent. Chromatographic separation was accomplished on an ACQUITY UPLC BEH C18 column with a mobile phase of acetonitrile-5 mM ammonium acetate solution (70:30, v/v) at a flow rate of 0.3 mL/min. Coptisine was selected as the internal standard. The protonated analytes were determined with MRM in the positive ion mode. The assay exhibited a linear dynamic range of 1.0-1000 ng/mL for palmatine in each biological matrix and the low limit of quantification was 1.0 ng/mL. Non-compartmental pharmacokinetic parameters indicated that there is a significant difference in the apparent distribution volume and half-life between intragastric and intravenous administration modes. Palmatine could be detected in different tissues and the content in liver and kidney is relatively high, suggesting that liver and kidney might be the targeting organs of palmatine. The plasma protein binding rate test showed that the percent binding of palmatine is medium, and was found to be higher in human than in rats.