Diagnostic and predictive values of circulating tetrahydrobiopterin levels as a novel biomarker in patients with thoracic and abdominal aortic aneurysms

Expand the success of screening to reduce aortic aneurysm mortality: progress interpretation and new fronts

Aortic aneurysm is a leading cause of death across the world. Many victicms carry it without knowing. Ruputre of aortic aneurysms leads to devastating sudden death. This brings trauma to families and our society. Based upon sound results out of several cohort studies, US Preventive Services Task Force (USPST) crafted the 1st nationwide abdominal aorta aneurysm (AAA) screening program in 2005. It was renewed and expanded in subsequent revisions in 2014 and 2019. UK and Sweden estalished their own programs as well. Since then, a significant decline in AAA prevalence and mortality has been observed. Two decades into the practice, the state of the art on diagnostics, surgical approaches, and pharmacological options have drastically changed. Patients previously ineligible for treatment or inconclusive on diagnostics now have valid options. The screening program is on the verge for a bold expansion. In this review, we summarize the chroncles leading to the inception of the screening programs, progress in interpretation after implementation including gains, gaps and controversies, advents of new technologies and approaches, new fronts facing us, as well as priorities to be addressed in future phases. Particularly, screening asssys with a clinically tested biomarker, tetrahydrobiopterin (H4B), enables unpresended accessibility, consistency and throughput to accommodate the needs of a larger population. Furthermore, patients with AAAs at size below the eligibility threhold for surgical intervention (e.g., < 5.5 cm) can be treated with novel oral medications. Confronting factors such as changing demographics and COVID-19 aftermath are putting up new challenges. Nevertheless, running a program at national scale demands both unwavering commitment and agile fine-tuning. Technical innovation will be an indispensable chapter of its continued success. The burden of aortic aneurysm-led sudden death is too heavy for any family and the society to bear; it is time to step up our resolve with additional capacities as discussed in the present review.

SENP3 Drives Abdominal Aortic Aneurysm Development by Regulating Ferroptosis via De-SUMOylation of CTH

Abdominal aortic aneurysm (AAA) is a high-risk inflammatory disorder. SENP3, a SUMO2/3-specific protease, is closely involved in the development of cancer. In this study, the aim is to explore the role of SENP3 in macrophages in AAA. It is found that the protein expression of SENP3 is significantly upregulated in both human and murine AAA specimens. SENP3 expression is negatively regulated by the E3 ubiquitin ligase STUB1/CHIP. Furthermore, myeloid-specific SENP3 knockout inhibited AAA formation in both AngII- and CaCl2-induced mouse models. SENP3 deficiency repressed AAA lesion macrophage infiltration and inflammatory response. Mechanistic studies identified Cystathionine Gamma-Lyase (CTH), a critical enzyme involved in hydrogen sulfide production, as a target protein of SENP3 that mediated the exacerbating effects of SENP3 on ferroptosis and inflammatory programs in macrophages. SUMO-3 modification at Lysine 361 promoted CTH protein stability, whereas de-SUMOylation by SENP3 facilitated its proteasome-dependent degradation. Most importantly, it is found that CTH inhibitor counteracted the protective effect of SENP3 deficiency on AAA. Additionally, supplementation with ATB346, a novel H2S-donating naproxen derivative, prevented AAA development in mice. These studies suggest that SENP3-mediated CTH deSUMOylation regulates macrophage ferroptosis and AAA development. The SENP3/CTH axis is therefore an important therapeutic target for aortic aneurysmal diseases.

Dispel some mist on circulating biopterins: measurement, physiological interval and pathophysiological implication

BACKGROUND AND AIMS

Biopterins, including tetrahydrobiopterin (BH4), dihydrobiopterin (BH2), and biopterin (B), were crucial enzyme cofactors in vivo. Despite their recognized clinical significance, there remain notable research gaps and controversies surrounding experimental outcomes. This study aims to clarify the biopterins-related issues, including analytical art, physiological intervals, and pathophysiological implications.

MATERIALS AND METHODS

A novel LC-MS/MS method was developed to comprehensively profile biopterins in plasma, utilizing chemical derivatization and cold-induced phase separation. Subsequently, apparently healthy individuals were enrolled to investigate the physiological ranges. And the relationships between biopterins and biochemical indicators were analyzed to explore the pathophysiological implications.

RESULTS

The developed method was validated as reliable for detecting biopterins across the entire physiological range. Timely anti-oxidation was found to be essential for accurate assessment of biopterins. The observed overall mean ± SDs levels were 3.51 ± 0.94, 1.54 ± 0.48, 2.45 ± 0.84 and 5.05 ± 1.14 ng/mL for BH4, BH2, BH4/BH2 and total biopterins. The status of biopterins showed interesting correlations with age, gender, hyperuricemia and overweight.

CONCLUSION

In conjunction with proper anti-oxidation, the newly developed method enables accurate determination of biopterins status in plasma. The observed physiological intervals and pathophysiological implications provide fundamental yet inspiring support for further clinical researches.

Murine double minute 2-mediated estrogen receptor 1 degradation activates macrophage migration inhibitory factor to promote vascular smooth muscle cell dedifferentiation and oxidative stress during thoracic aortic aneurysm progression

Estrogen receptor 1 (ESR1) has been recently demonstrated as a potential diagnostic biomarker for thoracic aortic aneurysm (TAA). However, its precise role in the progression of TAA remains unclear. In this study, TAA models were established in ApoE-knockout mice and primary mouse vascular smooth muscle cells (VSMCs) through treatment with angiotensin (Ang) II. Our findings revealed a downregulation of ESR1 in Ang II-induced TAA mice and VSMCs. Upregulation of ESR1 mitigated expansion and cell apoptosis in the mouse aorta, reduced pathogenetic transformation of VSMCs, and reduced inflammatory infiltration and oxidative stress both in vitro and in vivo. Furthermore, we identified macrophage migration inhibitory factor (MIF) as a biological target of ESR1. ESR1 bound to the MIF promoter to suppress its transcription. Artificial MIF restoration negated the mitigating effects of ESR1 on TAA. Additionally, we discovered that murine double minute 2 (MDM2) was highly expressed in TAA models and mediated protein degradation of ESR1 through ubiquitination modification. Silencing of MDM2 reduced VSMC dedifferentiation and suppressed oxidative stress. However, these effects were reversed upon further silencing of ESR1. In conclusion, this study demonstrates that MDM2 activates MIF by mediating ESR1 degradation, thus promoting VSMC dedifferentiation and oxidative stress during TAA progression.

Reversal of Pulmonary Hypertension in a Human-Like Model: Therapeutic Targeting of Endothelial DHFR

BACKGROUND

Pulmonary hypertension (PH) is a progressive disorder characterized by remodeling of the pulmonary vasculature and elevated mean pulmonary arterial pressure, resulting in right heart failure.

METHODS

Here, we show that direct targeting of the endothelium to uncouple eNOS (endothelial nitric oxide synthase) with DAHP (2,4-diamino 6-hydroxypyrimidine; an inhibitor of GTP cyclohydrolase 1, the rate-limiting synthetic enzyme for the critical eNOS cofactor tetrahydrobiopterin) induces human-like, time-dependent progression of PH phenotypes in mice.

RESULTS

Critical phenotypic features include progressive elevation in mean pulmonary arterial pressure, right ventricular systolic blood pressure, and right ventricle (RV)/left ventricle plus septum (LV+S) weight ratio; extensive vascular remodeling of pulmonary arterioles with increased medial thickness/perivascular collagen deposition and increased expression of PCNA (proliferative cell nuclear antigen) and alpha-actin; markedly increased total and mitochondrial superoxide production, substantially reduced tetrahydrobiopterin and nitric oxide bioavailabilities; and formation of an array of human-like vascular lesions. Intriguingly, novel in-house generated endothelial-specific dihydrofolate reductase (DHFR) transgenic mice (tg-EC-DHFR) were completely protected from the pathophysiological and molecular features of PH upon DAHP treatment or hypoxia exposure. Furthermore, DHFR overexpression with a pCMV-DHFR plasmid transfection in mice after initiation of DAHP treatment completely reversed PH phenotypes. DHFR knockout mice spontaneously developed PH at baseline and had no additional deterioration in response to hypoxia, indicating an intrinsic role of DHFR deficiency in causing PH. RNA-sequencing experiments indicated great similarity in gene regulation profiles between the DAHP model and human patients with PH.

CONCLUSIONS

Taken together, these results establish a novel human-like murine model of PH that has long been lacking in the field, which can be broadly used for future mechanistic and translational studies. These data also indicate that targeting endothelial DHFR deficiency represents a novel and robust therapeutic strategy for the treatment of PH.