Deficiency of proline/serine-rich coiled-coil protein 1 (PSRC1) accelerates trimethylamine N-oxide-induced atherosclerosis in ApoE-/- mice.

AIMS: The main therapeutic strategies for coronary artery disease (CAD) are mainly based on the correction of abnormal cholesterol levels; however, residual risks remain. The newly proven gut microbial metabolite trimethylamine N-oxide (TMAO) linked with CAD has broadened our horizons. In this study, we determined the role of proline/serine-rich coiled-coil protein 1 (PSRC1) in TMAO-driven atherosclerosis. METHODS AND RESULTS: We first analyzed the levels of TMAO and PSRC1 in patients with or without atherosclerosis with a target LDL-C < 1.8 mmol/L. Plasma TMAO levels were increased and negatively associated with decreased PSRC1 in peripheral blood mononuclear cells. Animals and in vitro studies showed that TMAO inhibited macrophage PSRC1 expression due to DNA hypermethylation of CpG islands. ApoE-/- mice fed a choline-supplemented diet exhibited reduced PSRC1 expression accompanied by increased atherosclerotic lesions and plasma TMAO levels. We further deleted PSRC1 in apoE-/- mice and PSRC1 deficiency significantly accelerated choline-induced atherogenesis, characterized by increased macrophage infiltration, foam cell formation and M1 macrophage polarization. Mechanistically, we overexpressed and knocked out PSRC1 in cultured macrophages to explore the mechanisms underlying TMAO-induced cholesterol accumulation and inflammation. PSRC1 deletion impaired reverse cholesterol transport and enhanced cholesterol uptake and inflammation, while PSRC1 overexpression rescued the proatherogenic phenotype observed in TMAO-stimulated macrophages, which was partially attributed to sulfotransferase 2B1b (SULT2B1b) inhibition. CONCLUSIONS: Herein, clinical data provide evidence that TMAO may participate in the development of CAD beyond well-controlled LDL-C levels. Our work also suggests that PSRC1 is a negative regulator mediating the unfavorable effects of TMAO-containing diets. Therefore, PSRC1 overexpression and reduced choline consumption may further alleviate atherosclerosis.

Deficiency of PSRC1 accelerates atherosclerosis by increasing TMAO production via manipulating gut microbiota and flavin monooxygenase 3.

Maladaptive inflammatory and immune responses are responsible for intestinal barrier integrity and function dysregulation. Proline/serine-rich coiled-coil protein 1 (PSRC1) critically contributes to the immune system, but direct data on the gut microbiota and the microbial metabolite trimethylamine N-oxide (TMAO) are lacking. Here, we investigated the impact of PSRC1 deletion on TMAO generation and atherosclerosis. We first found that PSRC1 deletion in apoE-/- mice accelerated atherosclerotic plaque formation, and then the gut microbiota and metabolites were detected using metagenomics and untargeted metabolomics. Our results showed that PSRC1 deficiency enriched trimethylamine (TMA)-producing bacteria and functional potential for TMA synthesis and accordingly enhanced plasma betaine and TMAO production. Furthermore, PSRC1 deficiency resulted in a proinflammatory colonic phenotype that was significantly associated with the dysregulated bacteria. Unexpectedly, hepatic RNA-seq indicated upregulated flavin monooxygenase 3 (FMO3) expression following PSRC1 knockout. Mechanistically, PSRC1 overexpression inhibited FMO3 expression in vitro, while an ERα inhibitor rescued the downregulation. Consistently, PSRC1-knockout mice exhibited higher plasma TMAO levels with a choline-supplemented diet, which was gut microbiota dependent, as evidenced by antibiotic treatment. To investigate the role of dysbiosis induced by PSRC1 deletion in atherogenesis, apoE-/- mice were transplanted with the fecal microbiota from either apoE-/- or PSRC1-/-apoE-/- donor mice. Mice that received PSRC1-knockout mouse feces showed an elevation in TMAO levels, as well as plaque lipid deposition and macrophage accumulation, which were accompanied by increased plasma lipid levels and impaired hepatic cholesterol transport. Overall, we identified PSRC1 as an atherosclerosis-protective factor, at least in part, attributable to its regulation of TMAO generation via a multistep pathway. Thus, PSRC1 holds great potential for manipulating the gut microbiome and alleviating atherosclerosis.

Development of feather keratin nanoparticles and investigation of their hemostatic efficacy.

Chicken feathers are considered as the major waste in poultry industry, which are mostly constituted of keratin proteins. Development of feather keratin for biomedical application is very attractive for chicken feather recycling. Human hair keratins have been demonstrated the significant hemostatic efficacy in the previous studies, but there are few reports of feather keratin for the hemostatic application. Here, the chicken feather keratin nanoparticle was developed for use as a hemostatic agent. Keratin was extracted from chicken feather in the present study, and a modified ultrasonic dispersion method was used to prepare keratin nanoparticles. The characterizations of feather keratin extracts and nanoparticles were investigated, including electrophoretic separation, amino acid composition, particle size, zeta potential, morphology, chemical structure and crystal form. Additionally, the hemostatic efficacy in vitro and in vivo of keratin nanoparticles were also studied. The results of hemostatic tests showed that the bleeding time and blood loss in tail amputation and liver scratch rat models can be significantly decreased after application of feather keratin nanoparticles, which demonstrated the potential application of feather keratin nanoparticles for hemostasis.