Neuraminidase 1 Exacerbating Aortic Dissection by Governing a Pro-Inflammatory Program in Macrophages

Heterozygous interferon signaling deficient mice as animal models for Chikungunya virus infection in the heart

Although chikungunya virus (CHIKV)-caused cardiovascular diseases are frequently reported in clinics, the underlying mechanisms are poorly understood, which is primarily due to a lack of animal models. In this study, we report that CHIKV infection in homozygous interferon α/β receptor-deficient (ifnar1-/-) and interferon α/β/γ receptor-deficient (ifnag-/-) mice resulted in high viral loads in the hearts as early as day (D) 1 post-infection (p.i.) but with 100% mortality within three days p.i. In contrast, the heterozygous ifnar1+/-and ifnag+/- mice survived CHIKV infection and bore higher viral burdens in the heart tissues than the wild-type (WT) controls. Immunohistochemistry and flow cytometry revealed that more leukocytes, particularly neutrophils, infiltrated the heart of ifnag+/- and ifnar1+/- mice than WT mice. In addition, the Hematoxylin and Eosin staining analysis showed that CHIKV infection caused vasculitis in the left ventricles on D5 p.i. in both heterozygous groups and the vacuole formation and pyknosis in ifnar1+/- mice. Moreover, CHIKV infection may also lead to cardiac fibrosis, as indicated by the upregulation of the expression of the Connective Tissue Growth Factor gene in the hearts of ifnar1+/- mice. In summary, our data suggest that the heterozygous ifnar1+/- and ifnag+/- mice are invaluable for studying pathogenesis and testing therapeutic interventions for CHIKV-caused cardiac diseases.

Cell Type-Specific Relationships Among Immune Cells in Human Aortic Dissection Tissue

BACKGROUND

Although recent studies have revealed the importance of inflammation in the pathogenesis of aortic dissection (AD), little is known about the relationships among inflammatory cells in human AD tissue.

METHODS AND RESULTS

We assessed the relationships among various immune cell types, including neutrophils, macrophages (M1 and M2), B cells, and helper T cells (Th1, Th2, Th17, Treg and Tfh ) in human AD tissue. AD tissues displayed abundant infiltration of immune cells. Correlation analysis revealed two groups of highly correlated cell types: a group of neutrophils and M1 and M2 macrophages, and another group consisting of B cells and helper T cells. In one particular case of AD, we were able to analyze the correlations between neutrophils and M1 and M2 macrophages in the entry, border, and intact zones of the AD lesions. Neutrophils showed significant correlations with M1 and M2 macrophages in the border zones. The entry and border zones showed M1-dominant polarization, whereas the intact zone showed M2-dominant polarization.

CONCLUSIONS

These findings indicate the existence of cell type-specific and site-specific interactions among immune cell types in human AD tissues.

Neu1 deficiency and fibrotic lymph node microenvironment lead to imbalance in M1/M2 macrophage polarization

Macrophages play a pivotal role in tissue homeostasis, pathogen defense, and inflammation resolution. M1 and M2 macrophage phenotypes represent two faces in a spectrum of responses to microenvironmental changes, crucial in both physiological and pathological conditions. Neuraminidase 1 (Neu1), a lysosomal and cell surface sialidase responsible for removing terminal sialic acid residues from glycoconjugates, modulates several macrophage functions, including phagocytosis and Toll-like receptor (TLR) signaling. Current evidence suggests that Neu1 expression influences M1/M2 macrophage phenotype alterations in the context of cardiovascular diseases, indicating a potential role for Neu1 in macrophage polarization. For this reason, we investigated the impact of Neu1 deficiency on macrophage polarization in vitro and in vivo. Using bone marrow-derived macrophages (BMDMs) and peritoneal macrophages from Neu1 knockout (Neu1-/- ) mice and wild-type (WT) littermate controls, we demonstrated that Neu1-deficient macrophages exhibit an aberrant M2-like phenotype, characterized by elevated macrophage mannose receptor 1 (MMR/CD206) expression and reduced responsiveness to M1 stimuli. This M2-like phenotype was also observed in vivo in peritoneal and splenic macrophages. However, lymph node (LN) macrophages from Neu1-/- mice exhibited phenotypic alterations with reduced CD206 expression. Further analysis revealed that peripheral LNs from Neu1-/- mice were highly fibrotic, with overexpression of transforming growth factor-beta 1 (TGF-β1) and hyperactivated TGF-β signaling in LN macrophages. Consistently, TGF-β1 was found to alter M1/M2 macrophage polarization in vitro. Our findings showed that Neu1 deficiency prompts macrophages towards an M2 phenotype and that microenvironmental changes, particularly increased TGF-β1 in fibrotic tissues such as peripheral LNs in Neu1-/- mice, further influence M1/M2 macrophage polarization, highlighting its sensitivity to the local microenvironment. Therapeutic interventions targeting Neu1 or TGF-β signaling pathways may offer the potential to regulate macrophage behavior across different diseases.

Postoperative Prognostic Nutritional Index and Fibrinogen Could Well Predict Poor Prognosis of Acute Type A Aortic Dissection Patients After Surgery

INTRODUCTION

Inflammatory and immunological factors play pivotal roles in the prognosis of acute type A aortic dissection. We aimed to evaluate the prognostic values of immune-inflammatory parameters in acute type A aortic dissection patients after surgery.

METHODS

A total of 127 acute type A aortic dissection patients were included. Perioperative clinical data were collected through the hospital's information system. The outcomes studied were delayed extubation, reintubation, and 30-day mortality. Multivariate logistic regression analysis and receiver operating characteristic analysis were used to screen the risk factors of poor prognosis.

RESULTS

Of all participants, 94 were male, and mean age was 51.95±11.89 years. The postoperative prognostic nutritional indexes were lower in delayed extubation patients, reintubation patients, and patients who died within 30 days. After multivariate regression analysis, the postoperative prognostic nutritional index was a protective parameter of poor prognosis. The odds ratios (95% confidence interval) of postoperative prognostic nutritional index were 0.898 (0.815, 0.989) for delayed extubation and 0.792 (0.696, 0.901) for 30-day mortality. Low postoperative fibrinogen could also well predict poor clinical outcomes. The odds ratios (95% confidence interval) of postoperative fibrinogen were 0.487 (0.291, 0.813) for delayed extubation, 0.292 (0.124, 0.687) for reintubation, and 0.249 (0.093, 0.669) for 30-day mortality.

CONCLUSION

Postoperative prognostic nutritional index and postoperative fibrinogen could be two promising markers to identify poor prognosis of acute type A aortic dissection patients after surgery.

Macrophage in Sporadic Thoracic Aortic Aneurysm and Dissection: Potential Therapeutic and Preventing Target

Thoracic aortic aneurysm and dissection (TAAD) is a life-threatening cardiovascular disorder lacking effective clinical pharmacological therapies. The underlying molecular mechanisms of TAAD still remain elusive with participation of versatile cell types and components including endothelial cells (ECs), smooth muscle cells (SMCs), fibroblasts, immune cells, and the extracellular matrix (ECM). The main pathological features of TAAD include SMC dysfunction, phenotypic switching, and ECM degradation, which is closely associated with inflammation and immune cell infiltration. Among various types of immune cells, macrophages are a distinct participator in the formation and progression of TAAD. In this review, we first highlight the important role of inflammation and immune cell infiltration in TAAD. Furthermore, we discuss the role of macrophages in TAAD from the aspects of macrophage origination, classification, and functions. On the basis of experimental and clinical studies, we summarize key regulators of macrophages in TAAD. Finally, we review how targeting macrophages can reduce TAAD in murine models. A better understanding of the molecular and cellular mechanisms of TAAD may provide novel insights into preventing and treating the condition.

Genetics of enzymatic dysfunctions in metabolic disorders and cancer

Inherited metabolic disorders arise from mutations in genes involved in the biogenesis, assembly, or activity of metabolic enzymes, leading to enzymatic deficiency and severe metabolic impairments. Metabolic enzymes are essential for the normal functioning of cells and are involved in the production of amino acids, fatty acids and nucleotides, which are essential for cell growth, division and survival. When the activity of metabolic enzymes is disrupted due to mutations or changes in expression levels, it can result in various metabolic disorders that have also been linked to cancer development. However, there remains much to learn regarding the relationship between the dysregulation of metabolic enzymes and metabolic adaptations in cancer cells. In this review, we explore how dysregulated metabolism due to the alteration or change of metabolic enzymes in cancer cells plays a crucial role in tumor development, progression, metastasis and drug resistance. In addition, these changes in metabolism provide cancer cells with a number of advantages, including increased proliferation, resistance to apoptosis and the ability to evade the immune system. The tumor microenvironment, genetic context, and different signaling pathways further influence this interplay between cancer and metabolism. This review aims to explore how the dysregulation of metabolic enzymes in specific pathways, including the urea cycle, glycogen storage, lysosome storage, fatty acid oxidation, and mitochondrial respiration, contributes to the development of metabolic disorders and cancer. Additionally, the review seeks to shed light on why these enzymes represent crucial potential therapeutic targets and biomarkers in various cancer types.

Non-steroidal anti-inflammatory drug target gene associations with major depressive disorders: a Mendelian randomisation study integrating GWAS, eQTL and mQTL Data

Previous observational studies reported associations between non-steroidal anti-inflammatory drugs (NSAIDs) and major depressive disorder (MDD), however, these associations are often inconsistent and underlying biological mechanisms are still poorly understood. We conducted a two-sample Mendelian randomisation (MR) study to examine relationships between genetic variants and NSAID target gene expression or DNA methylation (DNAm) using publicly available expression, methylation quantitative trait loci (eQTL or mQTL) data and genetic variant-disease associations from genome-wide association studies (GWAS of MDD). We also assessed drug exposure using gene expression and DNAm levels of NSAID targets as proxies. Genetic variants were robustly adjusted for multiple comparisons related to gene expression, DNAm was used as MR instrumental variables and GWAS statistics of MDD as the outcome. A 1-standard deviation (SD) lower expression of NEU1 in blood was related to lower C-reactive protein (CRP) levels of -0.215 mg/L (95% confidence interval (CI): 0.128-0.426) and a decreased risk of MDD (odds ratio [OR] = 0.806; 95% CI: 0.735-0.885; p = 5.36 × 10^-6). A concordant direction of association was also observed for NEU1 DNAm levels in blood and a risk of MDD (OR = 0.886; 95% CI: 0.836-0.939; p = 4.71 × 10^-5). Further, the genetic variants associated with MDD were mediated by NEU1 expression via DNAm (β = -0.519; 95% CI: -0.717 to -0.320256; p = 3.16 × 10^-7). We did not observe causal relationships between inflammatory genetic marker estimations and MDD risk. Yet, we identified a concordant association of NEU1 messenger RNA and an adverse direction of association of higher NEU1 DNAm with MDD risk. These results warrant increased pharmacovigilance and further in vivo or in vitro studies to investigate NEU1 inhibitors or supplements for MDD.

Changes in the gut microbiome of patients with type a aortic dissection

Objective

To investigate the characteristic changes in the gut microbiota of patients with type A aortic dissection (AAD) and provide a theoretical basis for future microbiome-oriented interventional studies.

Methods

High-throughput 16S rDNA sequencing was performed on the stool samples of patients with and without (healthy control subjects) AAD. Using alpha and beta diversity analysis, we compared the gut microbiota composition of 20 patients with AAD and 20 healthy controls matched for gender, age, BMI, and geographical region. The accuracy of AAD prediction by differential microbiome was calculated using the random forest machine learning model. Targeted measurement of the plasma concentration of short-chain fatty acids (SCFAs), which are the main metabolites of the gut microbiome, was performed using gas chromatography-mass spectrometry (GC-MS). Spearman's correlation analysis was conducted to determine the relationships of gut microbiome and SCFAs with the clinical characteristics of subjects.

Results

The differences in gut microbiota alpha diversity between patients with AAD and the healthy controls were not statistically significant (Shannon index: p = 0.19; Chao1: p = 0.4); however, the microbiota composition (beta diversity) was significantly different between the two groups (Anosim, p = 0.001). Bacteroidota was enriched at the phylum level, and the SCFA-producing genera Prevotella, Porphyromonas, Lachnospiraceae, and Ruminococcus and inflammation-related genera Fenollaria and Sutterella were enriched at the genus level in the AAD group compared with those in the control group. The random forest model could predict AAD from gut microbiota composition with an accuracy of 87.5% and the area-under-curve (AUC) of the receiver operating characteristic curve was 0.833. The SCFA content of patients with AAD was higher than that of the control group, with the difference being statistically significant (p < 0.05). The different microflora and SCFAs were positively correlated with inflammatory cytokines.

Conclusion

To the best of our knowledge, this is the first demonstration of the presence of significant differences in the gut microbiome of patients with AAD and healthy controls. The differential microbiome exhibited high predictive potential toward AAD and was positively correlated with inflammatory cytokines. Our results will assist in the development of preventive and therapeutic treatment methods for patients with AAD.

Neuraminidases-Key Players in the Inflammatory Response after Pathophysiological Cardiac Stress and Potential New Therapeutic Targets in Cardiac Disease

Glycoproteins and glycolipids on the cell surfaces of vertebrates and higher invertebrates contain α-keto acid sugars called sialic acids, terminally attached to their glycan structures. The actual level of sialylation, regulated through enzymatic removal of the latter ones by NEU enzymes, highly affects protein-protein, cell-matrix and cell-cell interactions. Thus, their regulatory features affect a large number of different cell types, including those of the immune system. Research regarding NEUs within heart and vessels provides new insights of their involvement in the development of cardiovascular pathologies and identifies mechanisms on how inhibiting NEU enzymes can have a beneficial effect on cardiac remodelling and on a number of different cardiac diseases including CMs and atherosclerosis. In this regard, a multitude of clinical studies demonstrated the potential of N-acetylneuraminic acid (Neu5Ac) to serve as a biomarker following cardiac diseases. Anti-influenza drugs i.e., zanamivir and oseltamivir are viral NEU inhibitors, thus, they block the enzymatic activity of NEUs. When considering the improvement in cardiac function in several different cardiac disease animal models, which results from NEU reduction, the inhibition of NEU enzymes provides a new potential therapeutic treatment strategy to treat cardiac inflammatory pathologies, and thus, administrate cardioprotection.

Lipoprotein sialylation in atherosclerosis: Lessons from mice

Sialylation is a dynamically regulated modification, which commonly occurs at the terminal of glycan chains in glycoproteins and glycolipids in eukaryotic cells. Sialylation plays a key role in a wide array of biological processes through the regulation of protein-protein interactions, intracellular localization, vesicular trafficking, and signal transduction. A majority of the proteins involved in lipoprotein metabolism and atherogenesis, such as apolipoproteins and lipoprotein receptors, are sialylated in their glycan structures. Earlier studies in humans and in preclinical models found a positive correlation between low sialylation of lipoproteins and atherosclerosis. More recent works using loss- and gain-of-function approaches in mice have revealed molecular and cellular mechanisms by which protein sialylation modulates causally the process of atherosclerosis. The purpose of this concise review is to summarize these findings in mouse models and to provide mechanistic insights into lipoprotein sialylation and atherosclerosis.