Thrombospondin-1 proteomimetic polymers exhibit anti-angiogenic activity in a neovascular age-related macular degeneration mouse model

Metabolomics unveils the role of pipecolic acid in regulating monocytes/macrophages-endothelial cells crosstalk to modulate choroidal neovascularization

Choroidal neovascularization (CNV) is a leading cause of vision loss in ocular diseases, including age-related macular degeneration (AMD). Despite extensive research, the underlying mechanisms of CNV remain incompletely understood, with a predominant focus on endothelial dysfunction. CNV, however, is a multi-cellular, multi-stage process involving complex interactions between endothelial cells, monocytes/macrophages, and other immune cells. In this study, we employed a dual-platform metabolomics approach combining liquid chromatography-mass spectrometry (LC-MS) and gas chromatography-mass spectrometry (GC-MS) to identify key metabolic alterations associated with CNV. Our results revealed significant changes in metabolic pathways during CNV progression. Using a myeloid lineage tracing mouse model, we further explored how Pipecolic acid regulates interactions between monocytes/macrophages and endothelial cells, key players in CNV development. We found that Pipecolic acid modulates monocyte/macrophage-endothelial cell crosstalk, inhibiting pathological angiogenesis. These results provide valuable insights into the molecular mechanisms driving CNV and highlight potential therapeutic targets for treating ocular neovascular diseases.

Protein-Like Polymers Targeting Keap1/Nrf2 as Therapeutics for Myocardial Infarction

Myocardial infarction (MI) results in oxidative stress to the myocardium and frequently leads to heart failure (HF). There is an unmet clinical need to develop therapeutics that address the inflammatory stress response and prevent negative left ventricular remodeling. Here, the Keap1/Nrf2 protein-protein interaction is specifically targeted, as Nrf2 activation is known to mitigate the inflammatory response following MI. This is achieved using a Nrf2-mimetic protein-like polymer (PLP) to inhibit the Keap1-Nrf2 interaction. The PLP platform technology provides stability in vivo, potent intracellular bioactivity, and multivalency leading to high avidity Keap1 binding. In vitro and in vivo assays to probe cellular activity and MI therapeutic utility are employed. These Keap1-inhibiting PLPs (Keap1i-PLPs) impart cytoprotection from oxidative stress via Nrf2 activation at sub-nanomolar concentrations in primary cardiomyocytes. Single-digit mg kg-1, single-dose, intravenous PLP administration significantly improves cardiac function in rats post-MI through immunomodulatory, anti-apoptotic, and angiogenic mechanisms. Thus Keap1i-PLPs disrupt key intracellular protein-protein interactions following intravenous, systemic administration in vivo. These results have broad implications not only for MI but also for other oxidative stress-driven diseases and conditions.

Proteomimetic polymer blocks mitochondrial damage, rescues Huntington's neurons, and slows onset of neuropathology in vivo

Recently, it has been shown that blocking the binding of valosin-containing protein (VCP) to mutant huntingtin (mtHtt) can prevent neuronal mitochondrial autophagy in Huntington's disease (HD) models. Herein, we describe the development and efficacy of a protein-like polymer (PLP) for inhibiting this interaction in cellular and in vivo models of HD. PLPs exhibit bioactivity in HD mouse striatal cells by successfully inhibiting mitochondrial destruction. PLP is notably resilient to in vitro enzyme, serum, and liver microsome stability assays, which render analogous control oligopeptides ineffective. PLP demonstrates a 2000-fold increase in circulation half-life compared to peptides, exhibiting an elimination half-life of 152 hours. In vivo efficacy studies in HD transgenic mice (R6/2) confirm the superior bioactivity of PLP compared to free peptide through behavioral and neuropathological analyses. PLP functions by preventing pathologic VCP/mtHtt binding in HD animal models; exhibits enhanced efficacy over the parent, free peptide; and implicates the PLP as a platform with potential for translational central nervous system therapeutics.

Thrombospondins: Conserved mediators and modulators of metazoan extracellular matrix

This review provides a personal overview of significant scientific developments in the thrombospondin field during the course of my career. Thrombospondins are multidomain, multimeric, calcium-binding extracellular glycoproteins with context-specific roles in tissue organisation. They act at cell surfaces and within ECM to regulate cell phenotype and signalling, differentiation and assembly of collagenous ECM, along with tissue-specific roles in cartilage, angiogenesis and synaptic function. More recently, intracellular, homeostatic roles have also been identified. Resolution of structures for the major domains of mammalian thrombospondins has facilitated major advances in understanding thrombospondin biology from molecule to tissue; for example, in illuminating molecular consequences of disease-causing coding mutations in human pseudoachrondroplasia. Although principally studied in vertebrates, thrombospondins are amongst the most ancient of animal ECM proteins, with many invertebrates encoding a single thrombospondin and the thrombospondin gene family of vertebrates originating through gene duplications. Moreover, thrombospondins form one branch of a thrombospondin superfamily that debuted at the origin of metazoans. The super-family includes additional sub-groups, present only in invertebrates, that differ in N-terminal domain organisation, share the distinctive TSP C-terminal region domain architecture and, to the limited extent studied to date, apparently contribute to tissue development and organisation. Finally, major lines of translational research are discussed, related to fibrosis; TSP1, TSP2 and inhibition of angiogenesis; and the alleviation of chronic cartilage tissue pathologies in pseudoachrondroplasia.

Conformational modulation and polymerization-induced folding of proteomimetic peptide brush polymers

Peptide-brush polymers generated by graft-through living polymerization of peptide-modified monomers exhibit high proteolytic stability, therapeutic efficacy, and potential as functional tandem repeat protein mimetics. Prior work has focused on polymers generated from structurally disordered peptides that lack defined conformations. To obtain insight into how the structure of these polymers is influenced by the folding of their peptide sidechains, a set of polymers with varying degrees of polymerization was prepared from peptide monomers that adopt α-helical secondary structure for comparison to those having random coil structures. Circular dichroism and nuclear magnetic resonance spectroscopy confirm the maintenance of the secondary structure of the constituent peptide when polymerized. Small-angle X-ray scattering (SAXS) studies reveal the solution-phase conformation of PLPs in different solvent environments. In particular, X-ray scattering shows that modulation of solvent hydrophobicity, as well as hydrogen bonding patterns of the peptide sidechain, plays an important role in the degree of globularity and conformation of the overall polymer, with polymers of helical peptide brushes showing less spherical compaction in conditions where greater helicity is observed. These structural insights into peptide brush folding and polymer conformation inform the design of these proteomimetic materials with promise for controlling and predicting their artificial fold and morphology.

Tissue-engineered mesenchymal stem cell constructs alleviate tendinopathy by suppressing vascularization

Tendinopathy leads to low-grade tissue inflammation and chronic damage, which progresses due to pathological imbalance in angiogenesis. Reducing early pathological vascularization may be a new approach in helping to regenerate tendon tissue. Conventional stem cell therapy and tissue engineering scaffolds have not been highly effective at treating tendinopathy. In this study, tissue engineered stem cells (TSCs) generated using human umbilical cord mesenchymal stem cells (hUC-MSCs) were combined with microcarrier scaffolds to limit excessive vascularization in tendinopathy. By preventing VEGF receptor activation through their paracrine function, TSCs reduced in vitro angiogenesis and the proliferation of vascular endothelial cells. TSCs also decreased the inflammatory expression of tenocytes while promoting their anabolic and tenogenic characteristics. Furthermore, local injection of TSCs into rats with collagenase-induced tendinopathy substantially reduced early inflammation and vascularization. Mechanistically, transcriptome sequencing revealed that TSCs could reduce the progression of pathological angiogenesis in tendon tissue, attributed to Rap1-mediated vascular inhibition. TSCs may serve as a novel and practical approach for suppressing tendon vascularization, and provide a promising therapeutic agent for early-stage clinical tendinopathy.

Enhanced Theranostic Efficacy of 89Zr and 177Lu-Labeled Aflibercept in Renal Cancer: A Viable Option for Clinical Practice

Vascular endothelial growth factor (VEGF) targeted therapy serves as an important therapeutic approach for renal cancer, but its clinical effectiveness is unsatisfactory. Moreover, there is a lack of reliable biomarkers for preoperative assessment of tumor VEGF expression. This study aimed to explore the potential for further applications of 177Lu/89Zr-labeled aflibercept (Abe), a VEGF-binding agent, in imaging visualization of VEGF expression and therapy for renal cancer. To determine specificity uptake in renal cancer, BALB/c mice with VEGF-expressing Renca tumor were intravenously injected with [89Zr]Zr-Abe, [177Lu]Lu-Abe, or Cy5.5-Abe and the blocking group was designed as a control group. PET, SPECT, and fluorescence images were acquired, and the biodistribution of [89Zr]Zr-Abe and [177Lu]Lu-Abe was performed. Additionally, the [177Lu]Lu-Abe, [177Lu]Lu-Abe-block, 177Lu only, Abe only, and PBS groups were compared for evaluation of the therapeutic effect. To assess the safety, we monitored and evaluated the body weight, blood biochemistry analysis, and whole blood analysis and major organs were stained with hematoxylin and eosin after [177Lu]Lu-Abe treatment. DOTA-Abe was successfully labeled with 177Lu and Df-Abe with 89Zr in our study. The uptake in tumor of [89Zr]Zr-Abe was significantly higher than that of [89Zr]Zr-Abe-block (P < 0.05) and provided excellent tumor contrast in PET images. [177Lu]Lu-Abe demonstrated promising tumor-specific targeting capability with a high and persistent tumor uptake. The standardized tumor volume of [177Lu]Lu-Abe was significantly smaller than those of other treatment groups (P < 0.05). [177Lu]Lu-Abe also had smaller tumor volumes and reduced expression of VEGF and CD31 compared to those of the control groups. Fluorescence images demonstrate higher tumor uptake in the Cy5.5-Abe group compared to the Cy5.5-Abe-block group (P < 0.05). In conclusion, [89Zr]Zr-Abe enables noninvasive analysis of VEGF expression, serving as a valuable tool for assessing the VEGF-targeted therapy effect. Additionally, all of the findings support the enhanced therapeutic efficacy and safety of [177Lu]Lu-Abe, making it a viable option for clinical practice in renal cancer.

Connective Tissue Growth Factor: Regulation, Diseases, and Drug Discovery

In drug discovery, selecting targeted molecules is crucial as the target could directly affect drug efficacy and the treatment outcomes. As a member of the CCN family, CTGF (also known as CCN2) is an essential regulator in the progression of various diseases, including fibrosis, cancer, neurological disorders, and eye diseases. Understanding the regulatory mechanisms of CTGF in different diseases may contribute to the discovery of novel drug candidates. Summarizing the CTGF-targeting and -inhibitory drugs is also beneficial for the analysis of the efficacy, applications, and limitations of these drugs in different disease models. Therefore, we reviewed the CTGF structure, the regulatory mechanisms in various diseases, and drug development in order to provide more references for future drug discovery.