Angiotensin-converting enzyme 2: a key enzyme in key organs

Elucidating emerging signaling pathways driving endothelial dysfunction in cardiovascular aging

The risk for developing cardiovascular diseases dramatically increases in older individuals, and aging vasculature plays a crucial role in determining their morbidity and mortality. Aging disrupts endothelial balance between vasodilators and vasoconstrictors, impairing function and promoting pathological vascular remodeling. In this Review, we discuss the impact of key and emerging molecular pathways that transduce aberrant inflammatory signals (i.e., chronic low-grade inflammation-inflammaging), oxidative stress, and mitochondrial dysfunction in aging vascular compartment. We focus on the interplay between these events, which contribute to generating a vicious cycle driving the progressive alterations in vascular structure and function during cardiovascular aging. We also discuss the primary role of senescent endothelial cells and vascular smooth muscle cells, and the potential link between vascular and myeloid cells, in impairing plaque stability and promoting the progression of atherosclerosis. The aim of this summary is to provide potential novel insights into targeting these processes for therapeutic benefit.

Multicenter and multimodal imaging study reveals rare fundus lesions in patients after SARS-CoV-2 infection

To define the characteristics of fundus manifestations in patients after SARS-CoV-2 infection with multimodal imaging techniques. This is a retrospective multicenter and multimodal imaging study including 90 patients. All patients with a visual complaint occurring immediately after SARS-CoV-2 infection were referred to six clinics between December 2022 and February 2023. Demographic information and the temporal relationship between SARS-CoV-2 infection and visual symptoms were documented. The characteristics of the fundus lesions were evaluated using multimodal imaging. Ninety patients from six hospitals were included in this study, including 24 males (26.67%) and 66 (73.33%) females. Seventy-eight patients (86.66%) (146 eyes) were diagnosed with Acute Macular Neuroretinopathy (AMN). The AMN patients were primarily young women (67.95%). Sixty-eight patients (87.18%) had AMN in both eyes. Thirty-eight eyes (24.36%) included Purtscher or Purtscher-like lesions. optical coherence tomography and infrared retinal photographs can show AMN lesions well. Eleven cases were diagnosed with simple Purtscher or Purtscher-like retinopathy (2 cases, 2.22%), Vogt‒Koyanagi‒Harada (VKH) syndrome or VKH-like uveitis (3 cases, 3.33%), multiple evanescent white-dot syndrome (MEWDS) (2 cases, 2.22%), and rhino-orbital-cerebral mucormycosis (ROCM) (5 cases, 5.56%). After SARS-CoV-2 infection, diversified fundus lesions were evident in patients with visual complaints. In this report, AMN was the dominant manifestation, followed by Purtscher or Purtscher-like retinopathy, MEWDS, VKH-like uveitis, and ROCM.

Nanocarriers Loaded with Oxygen to Improve the Protection of the Heart to be Transplanted

In the case of serious cardiovascular diseases, such as refractory heart failure, heart transplantation is the only possible intervention. Currently, the modes of organ transport in hypothermic cardioplegic solution do not allow the implantation of the heart beyond 4-5 hours from the explant. The heart being an organ with a greater consumption of oxygen and high metabolism than the brain, its transport in hypothermic cardioplegic solutions presents critical issues in terms of time and conservation. An ambitious goal of many researchers and clinicians is to minimize the hypoxia of the explanted heart and extend the permanence time in cardioplegic solution without damage from hypoxia. Adequately oxygenating the explanted organs may extend the usability time of the explanted organ. This challenge has been pursued for years with approaches that are often expensive, risky, and/or difficult to use. We propose to consider oxygenated nanocarriers realizing oxygen for a long time. In this way, it will also be possible to use organs from distant countries with respect to the recipient, thus exceeding the canonical 4-5 hours tolerated up to now. In addition to the lack of oxygen, the transplanted organ can undergo the accumulation of catabolites due to the lack of perfusion during transport. Therefore, nanocarriers can also be perfused in adequate solution during organ transportation. A better oxygenation improving the postoperative recovery of the transplanted heart will improve the recipient's quality of life.

Soluble Angiotensin Converting Enzyme 2 (ACE2) Is Upregulated and Soluble Endothelial Nitric Oxide Synthase (eNOS) Is Downregulated in COVID-19-induced Acute Respiratory Distress Syndrome (ARDS)

A damaged endothelium is an underlying condition of the many complications of COVID-19 patients. The increased mortality risk associated with diseases that have underlying endothelial dysfunction, such as acute respiratory distress syndrome (ARDS), suggests that endothelial (e) nitric oxide synthase (NOS)-derived nitric oxide could be an important defense mechanism. Additionally, intravenous recombinant angiotensin converting enzyme 2 (ACE2) was recently reported as an effective therapy in severe COVID-19, by blocking viral entry, and thus reducing lung injury. Very few studies exist on the prognostic value of endothelium-related protective molecules in severe COVID-19 disease. To this end, serum levels of eNOS, inducible (i) NOS, adrenomedullin (ADM), soluble (s) ACE2 levels, and serum (s) ACE activity were measured on hospital admission in 89 COVID-19 patients, hospitalized either in a ward or ICU, of whom 68 had ARDS, while 21 did not. In our cohort, the COVID-19-ARDS patients had considerably lower eNOS levels compared to the COVID-19 non-ARDS patients. On the other hand, sACE2 was significantly higher in the ARDS patients. iNOS, ADM and sACE activity did not differ. Our results might support the notion of two distinct defense mechanisms in COVID-19-derived ARDS; eNOS-derived nitric oxide could be one of them, while the dramatic rise in sACE2 may also represent an endogenous mechanism involved in severe COVID-19 complications, such as ARDS. These results could provide insight to therapeutical applications in COVID-19.