UC Riverside

Atherosclerosis is a chronic inflammatory disease characterized by theaccumulation of lipids, immune cells, necrotic cells, and other fibrous material in the sub- intimal space of large arteries. The lack of medical intervention or lifestyle changes can lead to advanced plaque development and plaque rupture, causing complete obstruction of blood flow, and ultimately death. Novel small noncoding RNAs (sncRNAs) including tRNA-derived small RNAs (tsRNAs) and rRNA-derived small RNAs (rsRNAs) have emerged as new players in regulating biological processes in various diseases but their role in atherosclerosis remains unknown. Using a novel PANDORA-seq method for the detection of highly modified sncRNAs, we identified many dysregulated tsRNAs and rsRNAs in the intima of high cholesterol diet (HCD)-fed LDL receptor-deficient (LDLR−/−) mice as compared with traditional small RNA sequencing results. HCD-induced intimal tsRNA-Arg-CCG may contribute to atherosclerosis by stimulating endothelial dysfunction. Emerging studies also suggest paternal dietary exposures may affect offspring health via tsRNA/rsRNA-mediated intergenerational transmission of paternal phenotypes. We found that paternal HCD feeding can increase atherosclerosis in F1 female, but not F1 male, offspring, which was associated with increased intimal inflammation in the F1 females. Using PANDORA-seq, we confirmed that tsRNAs and rsRNAs were also altered in the sperm of HCD-fed mice, which correlated with expression changes in sncRNA-biogenesis related genes in the epididymis. These studies highlight the function of tsRNA/rsRNA in disease development and the transmission of diseased phenotypes. In addition to the discovery of tsRNAs and rsRNAs in mediating atherosclerosis development, we also investigated the effects of adventitial fibroblast IκB kinase β (IKKβ) in regulating plaque stability. The involvement of the adventitia on plaque development has been largely overlooked. IKKβ is a known pro-inflammatory molecule and has been previously demonstrated to promote plaque development. Interestingly, we found that deficiency of IKKβ in fibroblasts rendered LDLR−/− mice to develop unstable plaques characterized with thin fibrous caps, large necrotic cores, and reduced collagen content. Single cell- sequencing analysis revealed decreased smooth muscle cell population in fibroblast IKKβ deficient aortas, possibly due to reduced fibroblast to smooth muscle cell differentiation. These results indicate that fibroblasts are crucial for maintaining the plaque stability in an IKKβ-dependent manner. Collectively, these studies revealed new contributors of atherosclerosis development, including novel tsRNAs/rsRNAs, paternal diet, and fibroblast IKKβ on atherosclerosis development and plaque stability.