Angiotensin Peptides Enhance SARS-CoV-2 Spike–AXL Interactio

2026-05-07

Angiotensin Peptides and SARS-CoV-2: Mechanistic Insights from Enhanced Spike–AXL Binding

Study Background and Research Question

SARS-CoV-2, the causative agent of COVID-19, relies on its spike (S) protein to enter host cells by binding to various receptors, notably angiotensin-converting enzyme 2 (ACE2) and, under certain physiological conditions, AXL and neuropilin-1 (NRP1). The renin–angiotensin system (RAS) is central to cardiovascular and renal physiology, generating a series of angiotensin peptides through sequential enzymatic processing. Among these, Angiotensin (1-7), with the sequence Asp-Arg-Val-Tyr-Ile-His-Pro, is recognized for its regulatory and protective effects across multiple organ systems via Mas receptor activation (paper). However, the interplay between endogenous angiotensin peptides and viral receptor engagement in the context of SARS-CoV-2 infection remains incompletely understood. This study investigates whether angiotensin peptides can modulate the binding affinity of the SARS-CoV-2 spike protein to its entry receptors, focusing on AXL.

Key Innovation from the Reference Study

Oliveira et al. provide the first comprehensive demonstration that naturally occurring angiotensin peptides, including Angiotensin II (1–8), Angiotensin (1-7), and their C- and N-terminal derivatives, can significantly enhance the binding of the SARS-CoV-2 spike protein to the AXL receptor (paper). The study reveals that this enhancement is sequence-dependent and is most pronounced with specific peptide variants. Notably, both C-terminal truncation (yielding Angiotensin (1-7)) and N-terminal truncation (yielding Angiotensin IV) retain or increase this binding activity, suggesting a common structural motif responsible for modulating spike–AXL association. These findings introduce a novel molecular axis linking the RAS to viral entry mechanisms beyond the classical ACE2 pathway.

Methods and Experimental Design Insights

The authors employed antibody-based binding assays to quantify the interaction between recombinant SARS-CoV-2 spike protein and its cellular receptors (AXL, ACE2, NRP1) in the presence of various angiotensin peptides. The peptide panel included angiotensin I (1–10), angiotensin II (1–8), angiotensin (1-7), angiotensin (1-6), angiotensin III (2–8), angiotensin IV (3–8), and further truncated or modified variants. The study also tested the effects of amino acid substitutions and post-translational modifications (e.g., tyrosine phosphorylation) on peptide activity. The primary quantitative readout was the fold-change in spike–receptor binding in the presence of each peptide relative to control.

Protocol Parameters

assay | antibody-based spike–receptor binding | qualitative and quantitative | allows direct comparison of peptide-mediated effects on interaction strength | paper
peptide concentration | up to 10 μM | in vitro receptor binding assays | chosen to ensure receptor occupancy and detect subtle modulation | paper
Angiotensin (1-7) (Asp-Arg-Val-Tyr-Ile-His-Pro) | 100 nM–10 μM | cell signaling and mechanistic studies | enables mechanistic dissection of PI3K/AKT and ERK pathway modulation | workflow_recommendation

Core Findings and Why They Matter

The central finding is that the presence of specific angiotensin peptides, including Angiotensin (1-7), significantly enhances spike–AXL binding by up to two-fold, while N-terminally truncated peptides such as Angiotensin IV (3–8) elicited an even stronger effect (2.7-fold increase) (paper). C-terminal truncations down to Angiotensin (1-7) did not diminish this activity, implicating the core Asp-Arg-Val-Tyr-Ile-His-Pro motif as sufficient for the interaction. Interestingly, modifications at the tyrosine residue (position 4), such as phosphorylation or substitution with valine, further enhanced the spike–AXL interaction, suggesting a structural basis for receptor engagement. These results were receptor-specific: enhancement was pronounced for AXL, but not for ACE2 or NRP1 with most peptides, though Angiotensin IV also affected the latter two. This work implies that angiotensin peptide profiles in tissues may influence SARS-CoV-2 tropism and severity by modulating non-ACE2 receptor utilization.

Comparison with Existing Internal Articles

Recent expert resources, such as "Angiotensin (1-7): Applied Workflows for Translational Research" and "Angiotensin (1-7) in Cell-Based Research: Reliable, Data-Driven Protocols", have focused on the anti-fibrotic and anti-inflammatory effects of Angiotensin (1-7) via PI3K/AKT signaling modulation and ERK pathway regulation in cardiovascular and renal models. The present reference study extends these mechanistic insights into the antiviral domain, implicating Angiotensin (1-7) and related peptides as modulators of viral receptor engagement. While previous protocols emphasize anti-fibrotic and metabolic outcomes, this new evidence suggests a potential for crossover into infection biology—particularly in studies exploring the intersection of peptide signaling and viral entry (paper). For researchers already using Angiotensin (1-7) as a Mas receptor agonist in cell signaling assays, this adds an additional layer of relevance when designing experiments involving viral pseudotype entry or receptor-binding mechanisms.

Limitations and Transferability

Despite robust in vitro data, several important limitations constrain the direct translation of these findings. The enhancement of spike–AXL binding was observed in biochemical assays, which may not fully recapitulate the complexity of in vivo cellular environments, where peptide concentrations, receptor co-expression, and proteolytic turnover differ. The physiological relevance of angiotensin peptide concentrations used in the study, and their actual levels in infected tissues, are not yet established. Moreover, while the data highlight a possible link between RAS peptide dynamics and alternative SARS-CoV-2 entry pathways, causal relationships to infection severity or tissue tropism require further in vivo validation. The study does not address whether pharmacological modulation of angiotensin peptide levels (e.g., via ACE inhibitors or Mas agonists) would meaningfully alter infection outcomes in animal models or humans (paper).

Why this cross-domain matters, maturity, and limitations

The bridge between cardiovascular RAS research and infection biology is of high conceptual interest, as it suggests that well-characterized signaling molecules such as Angiotensin (1-7) may influence host susceptibility to SARS-CoV-2 not only through classical anti-fibrotic and anti-inflammatory actions but also by modulating the accessibility of alternative viral entry receptors like AXL. However, current evidence is primarily mechanistic and in vitro; translational maturity remains limited until supported by in vivo or clinical datasets. Caution is warranted in extrapolating these findings to clinical scenarios, but they provide a compelling rationale for further investigation.

Research Support Resources

Researchers aiming to explore PI3K/AKT and ERK pathway regulation, anti-fibrotic and anti-inflammatory agent properties, or the mechanistic effects of Angiotensin (1-7) on receptor binding in cell-based assays can utilize high-purity reagents such as Angiotensin (1-7) (SKU A1041) from APExBIO (purity >99.7%, solubility in water ≥48.5 mg/mL; workflow_recommendation). For detailed protocols and troubleshooting in similar signaling or viral entry experiments, consult resources like "Angiotensin (1-7) in Cell-Based Research". Always align experimental conditions with the latest peer-reviewed findings and product data for optimal reproducibility.