Development of an Orthogonal Tie2 Ligand Resistant to Inhibition by Ang2

Engineered Receptor Capture Combined with Mass Spectrometry Enables High-Throughput Detection and Quantitation of SARS-CoV-2 Spike Protein

Mass spectrometry (MS) is a potentially powerful approach for the diagnostic detection of SARS-CoV-2 and other viruses. However, MS detection is compromised when viral antigens are present at low concentrations, especially in complex biological media. We hypothesized that viral receptors could be used for viral target capture to enable detection by MS under such conditions. This was tested using the extracellular domain of the SARS-CoV-2 receptor ACE2. To maximize recovery of the target protein, directed protein evolution was first used to increase the affinity of ACE2 for spike protein. This generated an evolved ACE2 with increased binding affinity for the spike protein receptor-binding domain (RBD). However, as with other affinity-enhanced evolved forms of ACE2, binding was sensitive to mutations in variant RBDs. As an alternative strategy to maximize capture, the native ACE2 extracellular domain was engineered for increased binding by the addition of an oligomerization scaffold to create pentameric ACE2. This bound extremely tightly to SARS-CoV-2 RBD, with an increase in apparent affinity of several thousand-fold over monomeric ACE2, and RBD retention of more than 8 h. Immobilization of multimeric ACE2 enabled quantitative enrichment of viral spike protein from saliva and increased the sensitivity of detection by MS. These data show that capture by engineered receptors combined with MS can be an effective, rapid method for detection and quantitation of target protein. A similar approach could be used for attachment proteins of other viruses or any target protein for which there are suitable receptors.

The positive implication of natural antioxidants on oxidative stress-mediated diabetes mellitus complications

The complementary intervention to modulate diabetes mellitus (DM) metabolism has recently brought the global attention, since DM has become among the global burden diseases. Where, several related pathways elevate the production of superoxide in consequences. For example, the flux of glycation-derived end products (AGEs) could lead to the deactivation of insulin signaling pathways. In that context, many vitamins and phytochemicals in natural sources have high antioxidant impacts that reduce oxidative stress and cell damages. These chemicals could be applied as bioactive antidiabetic agents. Their mode of actions could be from regulating the intracellular reactive oxygen species (ROS) which cause several pro-inflammatory pathways related to the oxidative stress (OS) and DM. Besides, they have a great potential to control the epigenetic mutations and hyperglycemia and help in back the blood glucose to the normal level. Therefore, the current review addresses the important role of natural functional antioxidants in DM management and its association with its OS complications.

Mechanisms of Flavonoids and Their Derivatives in Endothelial Dysfunction Induced by Oxidative Stress in Diabetes

Diabetic complications pose a significant threat to life and have a negative impact on quality of life in individuals with diabetes. Among the various factors contributing to the development of these complications, endothelial dysfunction plays a key role. The main mechanism underlying endothelial dysfunction in diabetes is oxidative stress, which adversely affects the production and availability of nitric oxide (NO). Flavonoids, a group of phenolic compounds found in vegetables, fruits, and fungi, exhibit strong antioxidant and anti-inflammatory properties. Several studies have provided evidence to suggest that flavonoids have a protective effect on diabetic complications. This review focuses on the imbalance between reactive oxygen species and the antioxidant system, as well as the changes in endothelial factors in diabetes. Furthermore, we summarize the protective mechanisms of flavonoids and their derivatives on endothelial dysfunction in diabetes by alleviating oxidative stress and modulating other signaling pathways. Although several studies underline the positive influence of flavonoids and their derivatives on endothelial dysfunction induced by oxidative stress in diabetes, numerous aspects still require clarification, such as optimal consumption levels, bioavailability, and side effects. Consequently, further investigations are necessary to enhance our understanding of the therapeutic potential of flavonoids and their derivatives in the treatment of diabetic complications.

The role of oxidative stress in diabetes mellitus-induced vascular endothelial dysfunction

Diabetes mellitus is a metabolic disease characterized by long-term hyperglycaemia, which leads to microangiopathy and macroangiopathy and ultimately increases the mortality of diabetic patients. Endothelial dysfunction, which has been recognized as a key factor in the pathogenesis of diabetic microangiopathy and macroangiopathy, is characterized by a reduction in NO bioavailability. Oxidative stress, which is the main pathogenic factor in diabetes, is one of the major triggers of endothelial dysfunction through the reduction in NO. In this review, we summarize the four sources of ROS in the diabetic vasculature and the underlying molecular mechanisms by which the pathogenic factors hyperglycaemia, hyperlipidaemia, adipokines and insulin resistance induce oxidative stress in endothelial cells in the context of diabetes. In addition, we discuss oxidative stress-targeted interventions, including hypoglycaemic drugs, antioxidants and lifestyle interventions, and their effects on diabetes-induced endothelial dysfunction. In summary, our review provides comprehensive insight into the roles of oxidative stress in diabetes-induced endothelial dysfunction.

The Screening of Therapeutic Peptides for Anti-Inflammation through Phage Display Technology

For the treatment of inflammatory illnesses such as rheumatoid arthritis and carditis, as well as cancer, several anti-inflammatory medications have been created over the years to lower the concentrations of inflammatory mediators in the body. Peptides are a class of medication with the advantages of weak immunogenicity and strong activity, and the phage display technique is an effective method for screening various therapeutic peptides, with a high affinity and selectivity, including anti-inflammation peptides. It enables the selection of high-affinity target-binding peptides from a complex pool of billions of peptides displayed on phages in a combinatorial library. In this review, we will discuss the regular process of using phage display technology to screen therapeutic peptides, and the peptides screened for anti-inflammation properties in recent years according to the target. We will describe how these peptides were screened and how they worked in vitro and in vivo. We will also discuss the current challenges and future outlook of using phage display to obtain anti-inflammatory therapeutic peptides.

Structural insights into the clustering and activation of Tie2 receptor mediated by Tie2 agonistic antibody

Angiopoietin (Angpt)-Tie receptor 2 (Tie2) plays key roles in vascular development and homeostasis as well as pathological vascular remodeling. Therefore, Tie2-agonistic antibody and engineered Angpt1 variants have been developed as potential therapeutics for ischemic and inflammatory vascular diseases. However, their underlying mechanisms for Tie2 clustering and activation remain elusive and the poor manufacturability and stability of Angpt1 variants limit their clinical application. Here, we develop a human Tie2-agonistic antibody (hTAAB), which targets the membrane proximal fibronectin type III domain of Tie2 distinct from the Angpt-binding site. Our Tie2/hTAAB complex structures reveal that hTAAB tethers the preformed Tie2 homodimers into polygonal assemblies through specific binding to Tie2 Fn3 domain. Notably, the polygonal Tie2 clustering induced by hTAAB is critical for Tie2 activation and are resistant to antagonism by Angpt2. Our results provide insight into the molecular mechanism of Tie2 clustering and activation mediated by hTAAB, and the structure-based humanization of hTAAB creates a potential clinical application.