Polycyclic aromatic hydrocarbons induce endothelial injury through miR-155 to promote atherosclerosis.

Polycyclic aromatic hydrocarbons (PAHs) are considered as an external factor that induces atherosclerotic cardiovascular disease. Although miR-155 is known to be involved in cardiovascular disease, whether it is involved in PAH-induced arteriosclerosis remains unclear. We evaluated the effects of PAHs on vascularization, permeability, and miR-155 expression in HUVECs. We found that PAHs-induced sclerosis of HUVECs was characterized by increasing permeability, decreasing proliferation, and vascular lumen number. The expression of miR-155 was upregulated by PAHs treatment, and transfection with miR-155 inhibitor could reverse above effect of PAHs-induced sclerosis. Meanwhile, transcriptome sequencing revealed that 63 genes were downregulated in the group of PAHs treatment alone, and were then upregulated in the miR-155 inhibitor group. These genes were mainly involved in complement and coagulation cascades, cytokine-cytokine receptor interaction, TNF signaling pathway, and NF-kappa B signaling pathway. Among these 63 genes, SERPIND1 was directly targeted and regulated by miR-155. Further in vivo experiments in ApoE-/- mice confirmed that PAH accelerates the development of arteriosclerosis by promoting the expression of miR-155 to downregulate the SERPIND1. Therefore, PAH exaggerates atherosclerosis by activating miR-155-dependent endothelial injury. This study provides a fundamental insight on the miR-155 mechanism for PAHs enhancing atherosclerosis and miR-155 potentially serving as a novel drug target.

Photochemical Reactivity of Humic Substances in an Aquatic System Revealed by Excitation-Emission Matrix Fluorescence.

The photochemical reactivity of humic substances plays a critical role in the global carbon cycle, and influences the toxicity, mobility, and bioavailability of contaminants by altering their molecular structure and the mineralization of organic carbon to CO2. Here, we examined the simulated irradiation process of Chinese standard fulvic acid (FA) and humic acid (HA) by using excitation-emission matrix fluorescence combined with fluorescence regional integration (FRI), parallel factor (PARAFAC) analysis, and kinetic models. Humic-like and fulvic-like materials were the main materials (constituting more than 90%) of both FA and HA, according to the FRI analysis. Four components were identified by the PARAFAC analysis: fulvic-like components composed of both carboxylic-like and phenolic-like chromophores (C1), terrestrial humic-like components primarily composed of carboxylic-like chromophores (C2), microbial humic-like overwhelming composed of phenolic-like fluorophores (C3), and protein-like components (C4). After irradiation for 72 h, the maximum fluorescence intensity (F max) of C1 and C2 of FA was reduced to 36.01-58.34%, while the F max of C3 of both FA and HA also decreased to 0-9.63%. By contrast, for HA, the F max of its C1 and C2 increased to 236.18-294.77% when irradiated for 72 h due to greater aromaticity and photorefractive tendencies. The first-order kinetic model (R 2 = 0.908-0.990) fitted better than zero-order kinetic model (R 2 = 0-0.754) for the C1, C2, and C3, of both FA and HA, during their photochemical reactivity. The photodegradation rate constant (k 1) of C1 had values (0.105 for FA; 0.154 for HA) that surpassed those of C2 (0.059 for FA, 0.079 for HA) and C3 (0.079 for both FA and HA) based on the first-order kinetic model. The half-life times of C1, C2, and C3 ranged from 6.61-11.77 h to 4.50-8.81 h for FA and HA, respectively. Combining an excitation-emission matrix with FRI and PARAFAC analyses is a powerful approach for elucidating changes to humic substances during their irradiation, which is helpful for predicting the environmental toxicity of contaminants in natural ecosystems.

[Effect of sunlight irradiation on fluorescence properties of dissolved organic matter].

Three-dimensional excitation emission matrix fluorescence spectroscopy (3DEEM) was used to investigate the effect of sunlight irradiation on the fluorescence properties of dissolved organic matter (DOM) from Lake Hongfeng and Nanming River waters and a commercial fluka humic acid (FHA). The results show that the DOM samples and FHA fluorescence properties changed under sunlight irradiation. Interestingly, the photodegradation characteristics were different between aquatic DOM and FHA. The fluorescence intensity of the apparent peaks A, B and C of lake and river water DOM decreased with sunlight irradiation. The initial 3DEEM of Fluka HA had only one fluorescence peak at lamda ex / lamda em = 275/500 nm, while two fluorescence peaks occurred at lamda ex / lamda em = 245/450 nm and 310/450 nm, respectively, after sunlight irradiation. lamda ex and lamda maxima of DOM decreased during 7 days of sunlight irradiation. Changes in r(A, C) of DOM and FHA with sunlight irradiation time suggest that fluorescence peaks A and C had different fluorescence loss rates, while peak C fluorophores were more susceptible to sunlight irradiation. FHA appeared to be less susceptible to photodegradation, and its r(A, C) remained almost the same before and after sunlight irradiation.

[Profile characteristics and seasonal variation of dissolved organic matter in Hongfeng Lake, Guizhou].

Dissolved organic carbon (DOC) and dissolved organic nitrogen (DON) are rarely measured together when studying dissolved organic matter (DOM) in lake water. DOC and DON concentrations were measured for a Karst plateau lake--Hongfeng Lake water for nearly two years. Profile characteristics and seasonal variation of dissolved organic matter were studied, and influencing factors were discussed. The results indicate that DOC concentration ranges from 1.60 mg x L(-1) to 3.08 mg x L(-1), DON ranges from 0.10 mg x L(-1) to 0.37 mg x L(-1) during studying period. DOC and DON concentrations change little from upper layer water to bottom during mixed periods, but show a general tendency for an upward increase during stratification periods. DOC concentration in the surface layer water (0-2 meters or 3 meters) of Hongfeng Lake is greatest from late spring to early summer or in summer, DON concentration is a little higher from late spring to early summer. Comparing the seasonal variation trend of DOC with that of chla and rainfall we draw a conclusion that the bioactivity of algae and DOM input from the watershed directly result in the seasonal variation mode of DOM in surface layer water. The C/N ratio of DOM generally increases with the increase of depth, but this trend changes at HF-S site in summer. At the depth of 12m, DOC and DON concentrations increase with the increase of depth; the C/N ratio of DOM decreases from 18.1 at the depth of 12 m to 14.9 at the depth of 14 m, and decreases continually with the increase of depth. A possible cause is the decomposition of POM, which forms an autochthonous source of DOM.