Abstract The mechanism of cardiovascular diseases (CVDs) is complex and threatens human health. Cardiomyocyte death is an important participant in the pathophysiological basis of CVDs. Ferroptosis is a new type of iron-dependent programmed cell death caused by excessive accumulation of iron-dependent lipid peroxides and reactive oxygen species (ROS) and abnormal iron metabolism. Ferroptosis differs from other known cell death pathways, such as apoptosis, necrosis, necroptosis, autophagy and pyroptosis. Several compounds have been shown to induce or inhibit ferroptosis by regulating related key factors or signalling pathways. Recent studies have confirmed that ferroptosis is associated with the development of diverse CVDs and may be a potential therapeutic drug target for CVDs. In this review, we summarize the characteristics and related mechanisms of ferroptosis and focus on its role in CVDs, with the goal of inspiring novel treatment strategies. 

/pdf/emerging-roles-of-ferroptosis-in-cardiovascular-diseases-1i33bf2a.pdf

Emerging roles of ferroptosis in cardiovascular diseases

Toll-like receptor 2 and 4 (TLR2, TLR4) signaling is implicated in atherosclerotic plaque formation. The two-stage master regulator Virtual Inference of Protein-activity by Enriched Regulon (VIPER) analysis of macrophage TLR2 and TLR4 signature genes integrated with coexpression network genes derived from 371 patient-derived carotid specimens identifies activated RNA polymerase II transcriptional coactivator p15 (SUB1/Sub1, PC4) as a master regulon in the atherogenic TLR response. It is found that TLR2 and TLR4 signaling is proinflammatory and proatherosclerotic in chow-fed apolipoprotein E-deficient (ApoE-/- ) mice. Through transgenic myeloid-specific Sub1 knockout in ApoE-/- mice, it is discovered that these proatherosclerotic effects of TLR2 and TLR4 signaling are mediated by Sub1. Sub1 knockout in macrophages enhances anti-inflammatory M2 macrophage polarization and cholesterol efflux. Irradiated low density lipoprotein receptor-deficient (Ldlr-/- ) mice transplanted with Sub1-/- murine bone marrow display reduced atherosclerosis. Promoter analysis reveals Sub1-dependent activation of interferon regulatory factor 1 (Irf1) transcription in a casein kinase 2 (Ck2)-dependent manner, and Sub1-knockout macrophages display decreased Irf1 expression. Artificial Irf1 overexpression in Sub1-knockout macrophages enhances proinflammatory M1 skewing and lowers cholesterol clearance. In conclusion, the TLR master regulon Sub1, and its downstream effect on the transcription factor Irf1, promotes a proinflammatory M1 macrophage phenotype and enhances atherosclerotic burden in vivo.

The Transcription Factor SUB1 Is a Master Regulator of the Macrophage TLR Response in Atherosclerosis

Positive cofactor 4 (PC4) is a transcriptional coactivator that plays important roles in transcription and DNA replication. In mammals, PC4 is phosphorylated by CK2, and this event downregulates its RNA polymerase II (RNAPII) coactivator function. This work describes the effect of fission yeast PC4 phosphorylation on RNAPII transcription in a cell extract, which closely resembles the cellular context. We found that fission yeast PC4 is strongly phosphorylated by the catalytic subunit of CK2 (Cka1), while the regulatory subunit (Ckb1) downregulates the PC4 phosphorylation. The addition of Cka1 to an in vitro transcription assay can diminish the basal transcription from the Ad-MLP promoter; however, the addition of recombinant fission yeast PC4 or Ckb1 can stimulate the basal transcription in a cell extract. Fission yeast PC4 is phosphorylated in a domain which has consensus phosphorylation sites for CK2, and two serine residues were identified as critical for CK2 phosphorylation. Mutation of one of the serine residues in PC4 does not completely abolish the phosphorylation; however, when the two serine residues are mutated, CK2 is no longer able to phosphorylate PC4. The mutant which is not phosphorylated is able to stimulate transcription even though it is previously phosphorylated by Cka1, while the wild type and the point mutant are inactivated by Cka1 phosphorylation, and they cannot stimulate transcription by RNAPII in cell extracts. Those results demonstrate that CK2 can regulate the coactivator function of fission yeast PC4 and suggests that this event could be important in vivo as well.

https://www.mdpi.com/1422-0067/23/16/9499/pdf?version=1661176277

The Catalytic Subunit of Schizosaccharomyces pombe CK2 (Cka1) Negatively Regulates RNA Polymerase II Transcription through Phosphorylation of Positive Cofactor 4 (PC4)

The last fifteen years have been marked by rapid progress in the study of neutrophils. The discovery of transcriptional plasticity of neutrophils, their phenotypic and functional heterogeneity contributed to launching active interdisciplinary studies on the role of neutrophils in various chronic inflammatory diseases. Increased systemic circulation of immunosuppressive neutrophils can be observed not only in sepsis, but also in chronic systemic inflammation, which, along with disorders of lipid metabolism, is the major mechanism of atherosclerosis development and progression. Monocytes, dendritic cells, Tlymphocytes and neutrophils are key participants and modulators of inflammation in atherosclerosis. Potential significance of immunosuppressive neutrophils in atherogenesis and regulation of inflammatory response in atherosclerosis has not been currently established. However, taking into account their possible effects upon T lymphocytes and innate immunity cells, the study of immunosuppressive neutrophils seems promising in the context of atherosclerosis and atherosclerotic cardiovascular diseases. The purpose of this study was to evaluate relationship between the numbers of circulating immunosuppressive neutrophils and subpopulations of T cells and monocytes in the patients with subclinical atherosclerosis. The study enrolled patients aged 40-64 years with subclinical atherosclerosis of peripheral arteries. Subpopulations of neutrophils, lymphocytes and monocytes were phenotyped by flow cytometry using “Navios 6/2” (Beckman Coulter). 133 patients, 65 (48.8%) males and 68 (51.2%) females were included into the study. Correlation analysis showed that increased number of circulating CD16 hi CD11b lo CD62L br neutrophils was associated with increased number of regulatory T lymphocytes. The patients with subclinical atherosclerosis and absolute numbers of circulating immunosuppressive neutrophils within the first quartile (&lt;136 cells/μL) had a statistically significantly lower number of regulatory T lymphocytes compared with patients in the 2-4 quartiles. An increase in immunosuppressive neutrophils was associated with decreased number of classical monocytes expressing TLR4 (r = -0.335; p = 0.004), and a decrease in TLR2 surface expression intensity (r = -0.268; p = 0.023) on the non-classical monocytes. In patients with subclinical atherosclerosis of 40-64 years old, an increase in immunosuppressive CD16 hi CD11b lo CD62L br neutrophils was associated with increase in regulatory T lymphocytes and nonclassical monocytes, as well as decrease in classic monocytes expressing TLR4, and lower intensity of TLR2 expression on the non-classical monocytes. 

Interactions between immunosuppressor neutrophiles, innate and adaptive immunity indexes in the patients with subclinical atherosclerosis

Increased inflammation and cytokine levels are considered risk factors and promoters of preterm birth (PTB). However, the regulatory mechanism of pregnancy-related inflammation remains unclear. Toll-like receptor 4 (TLR4) plays a critical role in inflammatory responses in various diseases. Therefore, our study aimed to investigate whether TLR4 is involved in the inflammatory responses during uterine activation for labor, with the goal of identifying potential biomarkers for uterine activation at term.We used flow cytometry to detect TLR4 expression on CD14+ maternal blood monocytes in the first, second, and third trimesters. ELISA was employed to measure TLR4 and cytokines levels in the maternal serum of term non-labor (TNL), term labor (TL) women and LPS induced preterm labor and PBS injected controls. TLR4siRNA was transfected into the human myometrial smooth muscle cells (HMSMCs), which were subsequently treated with IL-1β. The mRNA and protein levels of TLR4, uterine contraction-related protein connexin 43 (CX43), oxytocin receptor (OTR), MAPK/NF-κB signaling pathway, and cytokines were analyzed using qRT-PCR, western blotting, and immunohistochemistry.The study revealed TLR4 expression on CD14+ maternal blood monocytes was higher in the third trimester group compared to the first and second trimester groups (p<0.001). Maternal serum concentrations of TLR4 and cytokines were significantly higher in the TL group than the TNL group (p<0.001). TLR4, OTR, CX43, activated MAPK/NF-κB expression, and cytokines levels were upregulated in TL group, and similarly significantly higher in the LPS-induced preterm group than in the control group. Using the HMSMCs we demonstrated that TLR4siRNA transfection suppressed contractility. Interfering with TLR4 expression reduced the expression of OTR, CX43, cytokines, and MAPK/NF-κB activation. There was a significant positive relationship between TLR4 expression and the inflammatory status in the myometrium. ROC analysis indicated that TLR4 and cytokines may serve as potential biomarkers for predicting uterine activation for labor.Our data suggest that TLR4 and cytokines can act as stimulators of uterine activation for labor at term. Furthermore, the MAPK/NF-κB pathway appears to be one of the potential signaling pathways mediating TLR4’s regulation of parturition initiation.

Elevated expression of Toll-like receptor 4 and cytokines in both serum and myometrium at term may serve as promising biomarkers for uterine activation preceding labor

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The Transcription Factor SUB1 Is a Master Regulator of the Macrophage TLR Response in Atherosclerosis