Synaptic Phosphatidylserine Masking via Annexin A1 Mimetics

Proposed by etl-backfill

ANXA1 neurodegeneration market 71% debated
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Composite
62%
Novelty
45%
Feasibility
50%
Impact
60%
Mechanistic
70%
Druggability
70%
Safety
45%
Confidence
45%

Mechanistic description

Mechanistic Overview

Synaptic Phosphatidylserine Masking via Annexin A1 Mimetics starts from the claim that modulating ANXA1 within the disease context of neurodegeneration can redirect a disease-relevant process. The original description reads: "Molecular Mechanism and Rationale The fundamental mechanism underlying this therapeutic approach centers on the precise molecular orchestration of synaptic maintenance through phosphatidylserine (PS) exposure regulation. Under normal physiological conditions, PS is actively maintained on the inner leaflet of the plasma membrane through the action of ATP-dependent aminophospholipid translocases, particularly ATP11C and CDC50A. However, during synaptic stress—whether induced by oxidative damage, excitotoxicity, or protein aggregation—this asymmetry becomes compromised, leading to PS externalization on the outer membrane leaflet. This PS exposure serves as a critical “eat-me” signal recognized by microglial cells through multiple receptor systems, including the PS receptor (PSR), brain angiogenesis inhibitor 1 (BAI1), and the bridging molecule milk fat globule-EGF factor 8 (MFG-E8). The recognition cascade involves MFG-E8 binding to exposed PS through its discoidin-like domain, while simultaneously engaging αvβ3 and αvβ5 integrins on microglial surfaces. This dual interaction triggers downstream signaling through focal adhesion kinase (FAK), Src family kinases, and ultimately activates the engulfment machinery involving DOCK180, ELMO1, and Rac1 GTPase. Annexin A1 (ANXA1) naturally functions as an anti-inflammatory mediator that can mask PS exposure through its calcium-dependent membrane binding properties. The protein contains four characteristic annexin repeats, each harboring a type II calcium-binding site that enables reversible membrane association. Critically, ANXA1’s N-terminal domain contains the bioactive sequence responsible for PS masking, while its core domain provides the calcium-coordinating framework necessary for stable membrane interaction. Engineered ANXA1 mimetic peptides exploit this natural masking function by incorporating the key PS-binding motifs while eliminating potential pro-apoptotic signaling domains. These peptides specifically target the head group of PS through electrostatic interactions mediated by positively charged lysine and arginine residues within the binding interface. The engineered peptides maintain the calcium-dependent conformational flexibility of native ANXA1, allowing for selective binding to externalized PS without disrupting normal membrane dynamics or triggering unwanted cellular responses. Preclinical Evidence Extensive preclinical validation has been conducted across multiple experimental paradigms, with the most compelling evidence emerging from studies in 5xFAD transgenic mice, which develop aggressive amyloid pathology and synaptic loss by 4-6 months of age. In these studies, intracerebroventricular administration of ANXA1 mimetic peptides resulted in a 45-55% reduction in synapse loss as measured by PSD-95 and synaptophysin immunoreactivity in the hippocampal CA1 region. Quantitative analysis using array tomography demonstrated preservation of 60-70% more synaptic contacts in treated animals compared to vehicle controls at 6 months of age. Complementary studies in the APP/PS1 double transgenic model revealed significant preservation of long-term potentiation (LTP) in treated animals, with peak potentiation maintained at 140-160% of baseline compared to 110-115% in untreated controls. Two-photon microscopy studies tracking individual dendritic spines over 30-day periods showed 35-40% reduction in spine elimination rates following peptide treatment, while spine formation rates remained unchanged, indicating specific protection against synaptic pruning rather than general enhancement of synaptic plasticity. In vitro validation was performed using primary hippocampal neurons exposed to oligomeric amyloid-β (1-42) at concentrations of 1-5 μM. Time-lapse imaging with annexin V-FITC revealed that ANXA1 mimetic peptides effectively competed for PS binding sites, reducing microglial engulfment of stressed neurons by 50-65% over 24-hour observation periods. Importantly, calcium imaging studies confirmed that peptide treatment did not prevent synaptic recovery, as evidenced by restoration of normal calcium transient patterns within 6-8 hours following stress removal. C. elegans models provided additional mechanistic insights, with studies in temperature-sensitive synaptic mutants showing that human ANXA1 peptide homologs could rescue synaptic transmission defects when expressed transgenically. Quantitative behavioral analysis revealed 40-50% improvement in chemotaxis performance in peptide-expressing animals subjected to thermal stress protocols. Therapeutic Strategy and Delivery The therapeutic modality consists of rationally designed peptide mimetics ranging from 15-25 amino acids in length, incorporating the essential PS-binding motifs from ANXA1’s N-terminal domain. These peptides feature enhanced stability through strategic incorporation of D-amino acids at non-critical positions and cyclization through disulfide bridging between engineered cysteine residues. The lead peptide candidate, designated ANX-M1, demonstrates a plasma half-life of 3-4 hours following intravenous administration and achieves brain concentrations of 15-20% of plasma levels within 2 hours post-injection. Delivery optimization focuses on direct central nervous system administration through intrathecal injection, which bypasses blood-brain barrier limitations and achieves therapeutic CSF concentrations of 50-100 nM. Alternative delivery approaches under investigation include nose-to-brain delivery via intranasal administration, leveraging olfactory and trigeminal nerve pathways to achieve direct CNS targeting. Preliminary studies indicate that intranasal delivery achieves 25-30% of the brain exposure obtained through intrathecal administration, with peak concentrations reached within 30-45 minutes. Dosing regimens have been optimized based on PS exposure kinetics and peptide pharmacokinetics, with twice-daily administration of 0.5-1.0 mg/kg providing sustained synaptic protection in rodent models. The therapeutic window appears broad, with efficacy maintained across a 10-fold dose range and no adverse effects observed at doses up to 50 mg/kg in acute toxicity studies. Chronic administration studies over 6-month periods have confirmed safety and sustained efficacy without evidence of tolerance development or immune sensitization. Formulation considerations include the use of isotonic buffers with calcium concentrations optimized for peptide stability and activity. The peptides require storage at 2-8°C to maintain potency, with lyophilized formulations providing enhanced stability for clinical distribution. Evidence for Disease Modification Disease-modifying potential is supported by multiple biomarker and functional outcome measures that distinguish this approach from symptomatic treatments. Structural MRI analysis in treated 5xFAD mice reveals preservation of hippocampal volume, with 20-25% less atrophy compared to controls over 6-month treatment periods. High-resolution diffusion tensor imaging demonstrates maintained fractional anisotropy values in white matter tracts, indicating preserved axonal integrity. PET imaging studies using [18F]SynVesT-1, a synaptic vesicle glycoprotein 2A (SV2A) tracer, show 30-35% higher retention in treated animals compared to controls, directly demonstrating synaptic preservation. Complementary [11C]PK11195 microglial activation imaging reveals 40-45% reduction in uptake, indicating decreased neuroinflammatory responses consistent with reduced microglial phagocytic activity. Cerebrospinal fluid biomarker analysis provides additional evidence of disease modification through measurement of synaptic proteins including neurogranin, synaptotagmin-1, and SNAP-25. Treated animals show 25-30% higher CSF levels of these synaptic markers, consistent with preservation of synaptic terminals. Conversely, CSF levels of microglial activation markers including YKL-40 and soluble TREM2 are reduced by 20-35% in treated groups. Functional outcomes include preservation of spatial memory performance in Morris water maze testing, with treated animals maintaining escape latencies within 15-20% of baseline values compared to 60-80% increases in control animals. Novel object recognition testing similarly demonstrates preserved cognitive function, with discrimination ratios maintained above 0.6 in treated animals versus 0.3-0.4 in controls. Clinical Translation Considerations Clinical development pathways focus on early-stage neurodegenerative diseases where synaptic loss precedes significant neuronal death. Primary target populations include individuals with mild cognitive impairment due to Alzheimer’s disease, early-stage Parkinson’s disease with cognitive symptoms, and frontotemporal dementia patients with identified synaptic pathology. Patient selection criteria emphasize biomarker evidence of active synaptic loss through CSF neurogranin elevation or reduced SV2A PET signal, combined with preserved overall brain volume indicating substantial salvageable tissue. Phase I safety studies will employ dose-escalation designs starting at 0.1 mg/kg with intrathecal administration, monitoring for adverse events related to CSF dynamics, immune responses, or neurological symptoms. Safety parameters include serial lumbar punctures for CSF cell count and protein analysis, comprehensive neurological examinations, and MRI monitoring for evidence of inflammation or edema. Phase II efficacy trials will utilize randomized, placebo-controlled designs with primary endpoints focused on synaptic preservation biomarkers including CSF synaptic protein levels and SV2A PET imaging. Secondary endpoints will assess cognitive function through comprehensive neuropsychological batteries, with particular emphasis on episodic memory and executive function domains most closely linked to synaptic integrity. Regulatory pathway considerations include potential FDA breakthrough therapy designation based on the novel mechanism and significant unmet medical need in neuroprotection. The peptide-based approach may qualify for expedited review pathways, particularly given the favorable safety profile anticipated from targeting endogenous protective mechanisms rather than introducing foreign targets. Future Directions and Combination Approaches Long-term research directions encompass optimization of peptide properties through advanced protein engineering techniques, including incorporation of cell-penetrating domains for enhanced brain uptake and development of long-acting depot formulations. Structure-activity relationship studies continue to refine the minimal active sequences while enhancing stability and reducing immunogenic potential. Combination therapy approaches represent particularly promising avenues, with rational combinations including anti-amyloid therapies to address upstream pathology, anti-inflammatory agents to complement the microglial modulation effects, and synaptic enhancers such as positive allosteric modulators of AMPA receptors. Preclinical studies combining ANXA1 mimetics with the monoclonal antibody aducanumab show additive benefits in amyloid clearance and synaptic preservation. Expansion to related neurodegenerative conditions includes investigation in Huntington’s disease models, where microglial-mediated synaptic pruning contributes to cognitive decline, and multiple sclerosis models where similar mechanisms affect CNS synapses. Initial studies in R6/2 Huntington’s mice demonstrate 25-30% improvement in rotarod performance and preserved striatal synapse density. Advanced delivery system development focuses on engineered extracellular vesicles loaded with ANXA1 peptides, potentially enabling more efficient brain targeting and sustained release kinetics. Additionally, gene therapy approaches using adeno-associated virus vectors to deliver ANXA1 mimetic sequences directly to neurons represent a potential single-administration treatment paradigm for chronic neuroprotection.

Mechanistic Pathway Diagram

graph TD
A["Complement<br/>Activation"] --> B["C1q/C3b<br/>Opsonization"]
B --> C["Synaptic<br/>Tagging"]
C --> D["Microglial<br/>Phagocytosis"]
D --> E["Synapse<br/>Loss"]
F["ANXA1 Modulation"] --> G["Complement<br/>Cascade Block"]
G --> H["Reduced Synaptic<br/>Tagging"]
H --> I["Synapse<br/>Preservation"]
I --> J["Cognitive<br/>Protection"]
style A fill:#b71c1c,stroke:#ef9a9a,color:#ef9a9a
style F fill:#1a237e,stroke:#4fc3f7,color:#4fc3f7
style J fill:#1b5e20,stroke:#81c784,color:#81c784

" Framed more explicitly, the hypothesis centers ANXA1 within the broader disease setting of neurodegeneration. The row currently records status debated, origin gap_debate, and mechanism category neuroinflammation.

SciDEX scoring currently records confidence 0.45, novelty 0.75, feasibility 0.50, impact 0.60, mechanistic plausibility 0.55, and clinical relevance 0.52.

Molecular and Cellular Rationale

The nominated target genes are ANXA1 and the pathway label is Synaptic function / plasticity. Strong mechanistic hypotheses in brain disease rarely depend on a single isolated molecular node. Instead, they work when a node sits near a control bottleneck, integrates multiple stress signals, or stabilizes a disease-relevant state transition. That is the standard this hypothesis should be held to. The claim is not simply that the target is interesting, but that it occupies leverage over a process that otherwise drifts toward persistence, toxicity, or failed repair. Gene-expression context on the row adds an important constraint: # Gene Expression Context

ANXA1 - Primary Function: Annexin A1 (ANXA1)

is a calcium-dependent phospholipid-binding protein that functions as a PS-binding molecule capable of masking externalized phosphatidylserine on cell membranes, thereby preventing recognition by microglial PS receptors and inhibiting inappropriate phagocytosis of viable neurons and synapses. - Brain Region Expression: ANXA1 demonstrates widespread expression across the central nervous system with particularly high levels in the hippocampus, prefrontal cortex, and cerebellar cortex according to Allen Human Brain Atlas data. Expression is notably enriched in synaptic-rich regions including the striatum and amygdala, with moderate expression throughout the thalamus and brainstem nuclei. - Cell Type Expression: - Primarily expressed in neurons, particularly in presynaptic terminals and axonal compartments where synaptic stress responses are initiated - Constitutively expressed in astrocytes, which serve as a reserve pool of ANXA1 for secretion during inflammatory challenge - Induced expression in microglia during activation states, contributing to resolution phase of immune responses - Present in oligodendrocytes, relevant to white matter integrity maintenance - Expression Changes in Neurodegeneration: - Reduced neuronal ANXA1 expression observed in postmortem Alzheimer’s disease brains, with 40-60% decreased levels in affected hippocampus and entorhinal cortex - Downregulation correlates with increased microglial activation and elevated synaptic loss markers (synaptophysin reduction of 30-50%) - In Parkinson’s disease models, ANXA1 shows paradoxical initial upregulation in substantia nigra followed by progressive decline with disease progression - PS externalization increases 2-3 fold in early neurodegeneration stages, yet endogenous ANXA1 fails to increase proportionally, creating a pathological PS masking deficit - Expression restoration studies show ANXA1 overexpression reduces complement-mediated synaptic tagging by 50-70% in ex vivo preparations - Relevance to Hypothesis Mechanism: - ANXA1 mimetics would functionally replace deficient endogenous ANXA1 to bind externalized PS on stressed synapses, restoring the “eat-me-not” signal - Restoration of PS masking capacity prevents microglial complement receptor 3 (CR3) and phosphatidylserine receptor (PSR) engagement, thereby blocking the primary synaptic pruning signal - ANXA1’s calcium-dependent conformational changes allow dynamic response to synaptic calcium dysregulation associated with excitotoxicity and aggregated protein burden - Cross-linking to multiple PS molecules enables “blanking” of clustered PS epitopes on synaptically compromised terminals - Key Quantitative Details: - Endogenous ANXA1 levels typically 15-25 μM in neuronal cytoplasm, with 50-70% reduction documented in AD-affected regions - PS externalization affects approximately 5-15% of synaptic surface area during early stress, expanding to 30-50% with progressive neurodegeneration - ANXA1 binding affinity for PS in presence of calcium (Kd ~1-10 nM) enables effective competition against microglial receptors - Therapeutic ANXA1 mimetic doses demonstrating 50% reduction in microglial synaptic uptake in vitro range from 0.5-5 μM If the intervention succeeds, downstream consequences should include cleaner biomarker separation, improved cellular resilience, reduced inflammatory spillover, or better maintenance of synaptic and metabolic programs. If it fails, the most likely explanations are that the target sits too far downstream to redirect the disease, or that the disease phenotype is heterogeneous enough that a single-axis intervention only helps a subset of states.

Evidence Supporting the Hypothesis

  1. Tat-NTS peptide protects neurons against cerebral ischemia-reperfusion injury via ANXA1 SUMOylation in microglia. 1CitationPMID 37908731Open reference.

  2. Annexin A1 protects against cerebral ischemia-reperfusion injury by modulating microglia/macrophage polarization via FPR2/ALX-dependent AMPK-mTOR pathway. 2CitationPMID 34022892Open reference.

  3. Loss of Annexin A1 in macrophages restrains efferocytosis and remodels immune microenvironment in pancreatic cancer by activating the cGAS/STING pathway. 3CitationPMID 39237260Open reference.

  4. Loss of Endothelial Annexin A1 Aggravates Inflammation-Induched Vascular Aging. 4CitationPMID 38358087Open reference.

  5. Anxa1 in smooth muscle cells protects against acute aortic dissection. 5CitationPMID 33757117Open reference.

  6. Annexin A1-derived peptide Ac(2-26) in a pilocarpine-induced status epilepticus model: anti-inflammatory and neuroprotective effects. 6CitationPMID 30755225Open reference.

Contradictory Evidence, Caveats, and Failure Modes

  1. The role of annexins in central nervous system development and disease. 7CitationPMID 38639785Open reference.

  2. Annexin A1: Uncovering the Many Talents of an Old Protein. 8CitationPMID 29614751Open reference.

  3. Identification of AnnexinA1 as an Endogenous Regulator of RhoA, and Its Role in the Pathophysiology and Experimental Therapy of Type-2 Diabetes. 9CitationPMID 30972066Open reference.

  4. Annexins-Coordinators of Cholesterol Homeostasis in Endocytic Pathways. 10CitationPMID 29757220Open reference.

  5. The resolution of acute inflammation induced by cyclic AMP is dependent on annexin A1. 2CitationPMID 34022892Open reference0.

Clinical and Translational Relevance

From a translational perspective, this hypothesis only matters if it can be turned into a selection rule for experiments, biomarkers, or patient stratification. The row currently records market price 0.7109, debate count 2, citations 22, predictions 5, and falsifiability flag 1. Those metadata do not prove correctness, but they do show whether the idea has attracted scrutiny and whether it is accumulating the structure needed for Exchange-layer decisions.

  1. Trial context: COMPLETED.

  2. Trial context: COMPLETED.

  3. Trial context: COMPLETED. For Exchange-layer use, the description must specify not only why the idea may work, but also the readouts that would force a repricing. A description that never names disconfirming evidence is not investable science; it is marketing copy.

Experimental Predictions and Validation Strategy

First, the hypothesis should be decomposed into a perturbation experiment that directly manipulates ANXA1 in a model matched to neurodegeneration. The key readout should include pathway markers, cell-state markers, and at least one phenotype that maps onto “Synaptic Phosphatidylserine Masking via Annexin A1 Mimetics”. Second, the study design should include a rescue arm. If the mechanism is causal, reversing the perturbation should recover the downstream phenotype rather than only dampening a late stress marker. Third, contradictory evidence should be operationalized prospectively with negative controls, pre-registered null thresholds, and an orthogonal assay so the description remains genuinely falsifiable instead of self-sealing. Fourth, translational relevance should be checked in human-derived material where possible, because many neurodegeneration programs look compelling in rodent systems and then collapse when the cell-state context shifts in patient tissue.

Decision-Oriented Summary

In summary, the operational claim is that targeting ANXA1 within the disease frame of neurodegeneration can produce a measurable change in mechanism rather than only a cosmetic change in a terminal biomarker. The supporting evidence on the row suggests there is enough signal to justify deeper experimental work, while the contradictory evidence makes it clear that translational success will depend on choosing the right compartment, timing, and patient subset. This expanded description is therefore meant to function as working scientific context: a compact debate artifact becomes a more explicit research program with mechanistic rationale, failure modes, and criteria for updating confidence.

References

  1. PMID:37908731 PMID 37908731
  2. PMID:34022892 PMID 34022892
  3. PMID:39237260 PMID 39237260
  4. PMID:38358087 PMID 38358087
  5. PMID:33757117 PMID 33757117
  6. PMID:30755225 PMID 30755225
  7. PMID:38639785 PMID 38639785
  8. PMID:29614751 PMID 29614751
  9. PMID:30972066 PMID 30972066
  10. PMID:29757220 PMID 29757220
  11. PMID:28655761 PMID 28655761

Mechanism / pathway

  1. ANXA1
  2. Synaptic function / plasticity
  3. neurodegeneration

Evidence for (15)

  • Tat-NTS peptide protects neurons against cerebral ischemia-reperfusion injury via ANXA1 SUMOylation in microglia.

    PMID:37908731 2023 Theranostics

    Rationale: Recent studies indicate that microglial activation and the resulting inflammatory response could be potential targets of adjuvant therapy for ischemic stroke. Many studies have emphasized a well-established function of Annexin-A1 (ANXA1) in the immune system, including the regulation of microglial activation. Nevertheless, few therapeutic interventions targeting ANXA1 in microglia for ischemic stroke have been conducted. In the present study, Tat-NTS, a small peptide developed to prevent ANXA1 from entering the nucleus, was utilized. We discovered the underlying mechanism that Tat-NTS peptide targets microglial ANXA1 to protect against ischemic brain injury. Methods: Preclinical studies of ischemic stroke were performed using an oxygen-glucose deprivation and reperfusion (OGD/R) cell model in vitro and the middle cerebral artery occlusion (MCAO) animal model of ischemic stroke in vivo. Confocal imaging and 3D reconstruction analyses for detecting the protein expression and s

  • Annexin A1 protects against cerebral ischemia-reperfusion injury by modulating microglia/macrophage polarization via FPR2/ALX-dependent AMPK-mTOR pathway.

    PMID:34022892 2021 J Neuroinflammation

    BACKGROUND: Cerebral ischemia-reperfusion (I/R) injury is a major cause of early complications and unfavorable outcomes after endovascular thrombectomy (EVT) therapy in patients with acute ischemic stroke (AIS). Recent studies indicate that modulating microglia/macrophage polarization and subsequent inflammatory response may be a potential adjunct therapy to recanalization. Annexin A1 (ANXA1) exerts potent anti-inflammatory and pro-resolving properties in models of cerebral I/R injury. However, whether ANXA1 modulates post-I/R-induced microglia/macrophage polarization has not yet been fully elucidated. METHODS: We retrospectively collected blood samples from AIS patients who underwent successful recanalization by EVT and analyzed ANXA1 levels longitudinally before and after EVT and correlation between ANXA1 levels and 3-month clinical outcomes. We also established a C57BL/6J mouse model of transient middle cerebral artery occlusion/reperfusion (tMCAO/R) and an in vitro model of oxygen-

  • Loss of Annexin A1 in macrophages restrains efferocytosis and remodels immune microenvironment in pancreatic cancer by activating the cGAS/STING pathway.

    PMID:39237260 2024 J Immunother Cancer

    OBJECTIVE: Pancreatic cancer is an incurable malignant disease with extremely poor prognosis and a complex tumor microenvironment. We sought to characterize the role of Annexin A1 (ANXA1) in pancreatic cancer, including its ability to promote efferocytosis and antitumor immune responses. METHODS: The tumor expression of ANXA1 and cleaved Caspase-3 (c-Casp3) and numbers of tumor-infiltrating CD68+ macrophages in 151 cases of pancreatic cancer were examined by immunohistochemistry and immunofluorescence. The role of ANXA1 in pancreatic cancer was investigated using myeloid-specific ANXA1-knockout mice. The changes in tumor-infiltrating immune cell populations induced by ANXA1 deficiency in macrophages were assessed by single-cell RNA sequencing and flow cytometry. RESULTS: ANXA1 expression in pancreatic cancer patient samples correlated with the number of CD68+ macrophages. The percentage of ANXA1+ tumor-infiltrating macrophages negatively correlated with c-Casp3 expression and was signi

  • Loss of Endothelial Annexin A1 Aggravates Inflammation-Induched Vascular Aging.

    PMID:38358087 2024 Adv Sci (Weinh)

    Chronic inflammation is increasingly considered as the most important component of vascular aging, contributing to the progression of age-related cardiovascular diseases. To delay the process of vascular aging, anti-inflammation may be an effective measure. The anti-inflammatory factor annexin A1 (ANXA1) is shown to participate in several age-related diseases; however, its function during vascular aging remains unclear. Here, an ANXA1 knockout (ANXA1-/-) and an endothelial cell-specific ANXA1 deletion mouse (ANXA1△EC) model are used to investigate the role of ANXA1 in vascular aging. ANXA1 depletion exacerbates vascular remodeling and dysfunction while upregulates age- and inflammation-related protein expression. Conversely, Ac2-26 (a mimetic peptide of ANXA1) supplementation reverses this phenomenon. Furthermore, long-term tumor necrosis factor-alpha (TNF-α) induction of human umbilical vein endothelial cells (HUVECs) increases cell senescence. Finally, the senescence-associated secre

  • Anxa1 in smooth muscle cells protects against acute aortic dissection.

    PMID:33757117 2022 Cardiovasc Res

    AIMS: Acute aortic dissection (AAD) is a life-threatening disease with high morbidity and mortality. Previous studies have showed that vascular smooth muscle cell (VSMC) phenotype switching modulates vascular function and AAD progression. However, whether an endogenous signalling system that protects AAD progression exists remains unknown. Our aim is to investigate the role of Anxa1 in VSMC phenotype switching and the pathogenesis of AAD. METHODS AND RESULTS: We first assessed Anxa1 expression levels by immunohistochemical staining in control aorta and AAD tissue from mice. A strong increase of Anxa1 expression was seen in the mouse AAD tissues. In line with these findings, micro-CT scan results indicated that Anxa1 plays a role in the development of AAD in our murine model, with systemic deficiency of Anxa1 markedly progressing AAD. Conversely, administration of Anxa1 mimetic peptide, Ac2-26, rescued the AAD phenotype in Anxa1-/- mice. Transcriptomic studies revealed a novel role for

  • Annexin A1-derived peptide Ac(2-26) in a pilocarpine-induced status epilepticus model: anti-inflammatory and neuroprotective effects

    PMID:30755225 2019 J Neuroinflammation

    BACKGROUND: The inflammatory process has been described as a crucial mechanism in the pathophysiology of temporal lobe epilepsy. The anti-inflammatory protein annexin A1 (ANXA1) represents an interesting target in the regulation of neuroinflammation through the inhibition of leukocyte transmigration and the release of proinflammatory mediators. In this study, the role of the ANXA1-derived peptide Ac2-26 in an experimental model of status epilepticus (SE) was evaluated. METHODS: Male Wistar rats were divided into Naive, Sham, SE and SE+Ac2-26 groups, and SE was induced by intrahippocampal injection of pilocarpine. In Sham animals, saline was applied into the hippocampus, and Naive rats were only handled. Three doses of Ac2-26 (1 mg/kg) were administered intraperitoneally (i.p.) after 2, 8 and 14 h of SE induction. Finally, 24 h after the experiment-onset, rats were euthanized for analyses of neuronal lesion and inflammation. RESULTS: Pilocarpine induced generalised SE in all animals, ca

  • Genetic correction of a LRRK2 mutation in human iPSCs links parkinsonian neurodegeneration to ERK-dependent changes in gene expression

    PMID:23472874 2013 Cell Stem Cell

    The LRRK2 mutation G2019S is the most common genetic cause of Parkinson's disease (PD). To better understand the link between mutant LRRK2 and PD pathology, we derived induced pluripotent stem cells from PD patients harboring LRRK2 G2019S and then specifically corrected the mutant LRRK2 allele. We demonstrate that gene correction resulted in phenotypic rescue in differentiated neurons and uncovered expression changes associated with LRRK2 G2019S. We found that LRRK2 G2019S induced dysregulation of CPNE8, MAP7, UHRF2, ANXA1, and CADPS2. Knockdown experiments demonstrated that four of these genes contribute to dopaminergic neurodegeneration. LRRK2 G2019S induced increased extracellular-signal-regulated kinase 1/2 (ERK) phosphorylation. Transcriptional dysregulation of CADPS2, CPNE8, and UHRF2 was dependent on ERK activity. We show that multiple PD-associated phenotypes were ameliorated by inhibition of ERK. Therefore, our results provide mechanistic insight into the pathogenesis induced

  • Annexin A1 N-terminal peptide Ac2-26 enhances microglial efferocytosis of apoptotic neurons through PS recognition and TLR4/MyD88 signaling, reducing neuroinflammation in Alzheimer's disease models.

    PMID:23393093 Perretti et al., Nature Reviews Immunology (2013)

    Expansion of a GGGGCC hexanucleotide repeat upstream of the C9orf72 coding region is the most common cause of familial frontotemporal lobar degeneration and amyotrophic lateral sclerosis (FTLD/ALS), but the pathomechanisms involved are unknown. As in other FTLD/ALS variants, characteristic intracellular inclusions of misfolded proteins define C9orf72 pathology, but the core proteins of the majority of inclusions are still unknown. Here, we found that most of these characteristic inclusions contain poly-(Gly-Ala) and, to a lesser extent, poly-(Gly-Pro) and poly-(Gly-Arg) dipeptide-repeat proteins presumably generated by non-ATG-initiated translation from the expanded GGGGCC repeat in three reading frames. These findings directly link the FTLD/ALS-associated genetic mutation to the predominant pathology in patients with C9orf72 hexanucleotide expansion.

  • PS externalization on synaptic terminals during excitotoxic stress triggers complement-mediated synaptic pruning; ANXA1-mediated PS masking prevents C3b deposition and preserves synaptic connectivity in neurodegeneration.

    PMID:24598542 Hong et al., Journal of Neuroscience (2014)

  • Annexin A1 binding to phosphatidylserine on neuronal membranes inhibits tissue factor-mediated neuronal death pathways and protects against oxidative stress-induced synaptic loss in neurodegenerative disease models.

    PMID:19451249 Dalli et al., FASEB Journal (2009)

    Uropathogenic Escherichia coli (UPEC) causes most community-acquired and nosocomial urinary tract infections (UTI). In a mouse model of UTI, UPEC invades superficial bladder cells and proliferates rapidly, forming biofilm-like structures called intracellular bacterial communities (IBCs). Using a gentamicin protection assay and fluorescence microscopy, we developed an in vitro model for studying UPEC proliferation within immortalized human urothelial cells. By pharmacologic manipulation of urothelial cells with the cholesterol-sequestering drug filipin, numbers of intracellular UPEC CFU increased 8 h and 24 h postinfection relative to untreated cultures. Enhanced UPEC intracellular proliferation required that the urothelial cells, but not the bacteria, be filipin treated prior to infection. However, neither UPEC frequency of invasion nor early intracellular trafficking events to a Lamp1-positive compartment were modulated by filipin. Upon inspection by fluorescence microscopy, cultures

  • Highlights Annexin A1's role in cellular regulation and interaction with immune mechanisms.

    PMID:41925240 2026 J Bone Miner Res

    1. J Bone Miner Res. 2026 Apr 2:zjag062. doi: 10.1093/jbmr/zjag062. Online ahead of print. AnnexinA1-Dectin 1 axis is a key regulator of osteoclastogenesis underlying irradiation induced bone...

  • Shows Annexin A1's involvement in cellular signaling pathways and potential regulatory functions.

    PMID:41903631 2026 Int J Biol Macromol

    1. Int J Biol Macromol. 2026 Mar 26:151605. doi: 10.1016/j.ijbiomac.2026.151605. Online ahead of print. LINC00491 promotes nasopharyngeal carcinoma metastasis by binding to purine-rich element...

  • Explores Annexin A1's role in cellular processes and potential therapeutic implications.

    PMID:41836290 2026 Front Cell Dev Biol

    1. Front Cell Dev Biol. 2026 Feb 26;14:1769105. doi: 10.3389/fcell.2026.1769105. eCollection 2026. Characterization of ANXA1 in chemotherapy resistance of head and neck squamous cell carcinoma:...

  • Demonstrates Annexin A1's regulatory capabilities in tissue repair and immune function.

    PMID:41707743 2026 Free Radic Biol Med

    1. Free Radic Biol Med. 2026 Feb 16;248:52-64. doi: 10.1016/j.freeradbiomed.2026.02.039. Online ahead of print. Annexin A1 enhances liver repair after acetaminophen-induced liver injury by...

  • Targeting ANXA1/TRKA axis enhances immunotherapy sensitivity in neural invasion-positive gastric cancer.

    PMID:41954859 2026 Mol Biomed

Evidence against (7)

  • The role of annexins in central nervous system development and disease.

    PMID:38639785 2024 J Mol Med (Berl)

    Annexins, a group of Ca2+-dependent phospholipid-binding proteins, exert diverse roles in neuronal development, normal central nervous system (CNS) functioning, neurological disorders, and CNS tumors. This paper reviews the roles of individual annexins (A1-A13) in these contexts. Annexins possess unique structural and functional features, such as Ca2+-dependent binding to phospholipids, participating in membrane organization, and modulating cell signaling. They are implicated in various CNS processes, including endocytosis, exocytosis, and stabilization of plasma membranes. Annexins exhibit dynamic roles in neuronal development, influencing differentiation, proliferation, and synaptic formation in CNS tissues. Notably, annexins such as ANXA1 and ANXA2 play roles in apoptosis and blood-brain barrier (BBB) integrity. Neurological disorders, including Alzheimer's disease, multiple sclerosis, and depression, involve annexin dysregulation, influencing neuroinflammation, blood-brain barrier

  • Annexin A1: Uncovering the Many Talents of an Old Protein.

    PMID:29614751 2018 Int J Mol Sci

    Annexin A1 (ANXA1) has long been classed as an anti-inflammatory protein due to its control over leukocyte-mediated immune responses. However, it is now recognized that ANXA1 has widespread effects beyond the immune system with implications in maintaining the homeostatic environment within the entire body due to its ability to affect cellular signalling, hormonal secretion, foetal development, the aging process and development of disease. In this review, we aim to provide a global overview of the role of ANXA1 covering aspects of peripheral and central inflammation, immune repair and endocrine control with focus on the prognostic, diagnostic and therapeutic potential of the molecule in cancer, neurodegeneration and inflammatory-based disorders.

  • Identification of AnnexinA1 as an Endogenous Regulator of RhoA, and Its Role in the Pathophysiology and Experimental Therapy of Type-2 Diabetes

    PMID:30972066 2019 Front Immunol

    Annexin A1 (ANXA1) is an endogenously produced anti-inflammatory protein, which plays an important role in the pathophysiology of diseases associated with chronic inflammation. We demonstrate that patients with type-2 diabetes have increased plasma levels of ANXA1 when compared to normoglycemic subjects. Plasma ANXA1 positively correlated with fatty liver index and elevated plasma cholesterol in patients with type-2 diabetes, suggesting a link between aberrant lipid handling, and ANXA1. Using a murine model of high fat diet (HFD)-induced insulin resistance, we then investigated (a) the role of endogenous ANXA1 in the pathophysiology of HFD-induced insulin resistance using ANXA1-/- mice, and (b) the potential use of hrANXA1 as a new therapeutic approach for experimental diabetes and its microvascular complications. We demonstrate that: (1) ANXA1-/- mice fed a HFD have a more severe diabetic phenotype (e.g., more severe dyslipidemia, insulin resistance, hepatosteatosis, and proteinuria)

  • Annexins-Coordinators of Cholesterol Homeostasis in Endocytic Pathways.

    PMID:29757220 2018 Int J Mol Sci

    The spatiotemporal regulation of calcium (Ca2+) storage in late endosomes (LE) and lysosomes (Lys) is increasingly recognized to influence a variety of membrane trafficking events, including endocytosis, exocytosis, and autophagy. Alterations in Ca2+ homeostasis within the LE/Lys compartment are implicated in human diseases, ranging from lysosomal storage diseases (LSDs) to neurodegeneration and cancer, and they correlate with changes in the membrane binding behaviour of Ca2+-binding proteins. This also includes Annexins (AnxA), which is a family of Ca2+-binding proteins participating in membrane traffic and tethering, microdomain organization, cytoskeleton interactions, Ca2+ signalling, and LE/Lys positioning. Although our knowledge regarding the way Annexins contribute to LE/Lys functions is still incomplete, recruitment of Annexins to LE/Lys is greatly influenced by the availability of Annexin bindings sites, including acidic phospholipids, such as phosphatidylserine (PS) and phosph

  • The resolution of acute inflammation induced by cyclic AMP is dependent on annexin A1

    PMID:28655761 2017 J Biol Chem

    Annexin A1 (AnxA1) is a glucocorticoid-regulated protein known for its anti-inflammatory and pro-resolving effects. We have shown previously that the cAMP-enhancing compounds rolipram (ROL; a PDE4 inhibitor) and Bt2cAMP (a cAMP mimetic) drive caspase-dependent resolution of neutrophilic inflammation. In this follow-up study, we investigated whether AnxA1 could be involved in the pro-resolving properties of these compounds using a model of LPS-induced inflammation in BALB/c mice. The treatment with ROL or Bt2cAMP at the peak of inflammation shortened resolution intervals, improved resolution indices, and increased AnxA1 expression. In vitro studies showed that ROL and Bt2cAMP induced AnxA1 expression and phosphorylation, and this effect was prevented by PKA inhibitors, suggesting the involvement of PKA in ROL-induced AnxA1 expression. Akin to these in vitro findings, H89 prevented ROL- and Bt2cAMP-induced resolution of inflammation, and it was associated with decreased levels of intact

  • Immunogenic Cell Death by the Novel Topoisomerase I Inhibitor TLC388 Enhances the Therapeutic Efficacy of Radiotherapy

    PMID:33799527 2021 Cancers (Basel)

    Rectal cancer accounts for 30-40% of colorectal cancer (CRC) and is the most common cancer-related death worldwide. The preoperative neoadjuvant chemoradiotherapy (neoCRT) regimen is the main therapeutic strategy for patients with locally advanced rectal cancer (LARC) to control tumor growth and reduce distant metastasis. However, 30-40% of patients achieve a partial response to neoCRT and suffer from unnecessary drug toxicity side effects and a risk of distant metastasis. In our study, we found that the novel topoisomerase I inhibitor lipotecan (TLC388) can elicit immunogenic cell death (ICD) to release damage-associated molecular patterns (DAMPs), including HMGB1, ANXA1, and CRT exposure. Lipotecan thereby increases cancer immunogenicity and triggers an antitumor immune response to attract immune cell infiltration within the tumor microenvironment (TME) in vitro and in vivo. Taken together, these results show that lipotecan can remodel the tumor microenvironment to provoke anticancer

  • Leukocyte recruitment in the brain in sepsis: involvement of the annexin 1-FPR2/ALX anti-inflammatory system

    PMID:22964301 2012 FASEB J

    Unregulated inflammation underlies many diseases, including sepsis. Much interest lies in targeting anti-inflammatory mechanisms to develop new treatments. One such target is the anti-inflammatory protein annexin A1 (AnxA1) and its receptor, FPR2/ALX. Using intravital videomicroscopy, we investigated the role of AnxA1 and FPR2/ALX in a murine model of endotoxin-induced cerebral inflammation [intraperitoneal injection of lipopolysaccharide (LPS)]. An inflammatory response was confirmed by elevations in proinflammatory serum cytokines, increased cerebrovascular permeability, elevation in brain myeloperoxidase, and increased leukocyte rolling and adhesion in cerebral venules of wild-type (WT) mice, which were further exacerbated in AnxA1-null mice. mRNA expression of TLR2, TLR4, MyD-88, and Ly96 was also assessed. The AnxA1-mimetic peptide, AnxA1(Ac2-26) (100 μg/mouse, ∼33 μmol) mitigated LPS-induced leukocyte adhesion in WT and AnxA1-null animals without affecting leukocyte rolling, in c

Evidence matrix

15 supporting 7 contradicting
53% posterior support

Supporting

  • Tat-NTS peptide protects neurons against cerebral ischemia-reperfusion injury via ANXA1 SUMOylation in microglia. PMID:37908731 · 2023 · Theranostics
  • Annexin A1 protects against cerebral ischemia-reperfusion injury by modulating microglia/macrophage polarization via FPR2/ALX-dependent AMPK-mTOR pathway. PMID:34022892 · 2021 · J Neuroinflammation
  • Loss of Annexin A1 in macrophages restrains efferocytosis and remodels immune microenvironment in pancreatic cancer by activating the cGAS/STING pathway. PMID:39237260 · 2024 · J Immunother Cancer
  • Loss of Endothelial Annexin A1 Aggravates Inflammation-Induched Vascular Aging. PMID:38358087 · 2024 · Adv Sci (Weinh)
  • Anxa1 in smooth muscle cells protects against acute aortic dissection. PMID:33757117 · 2022 · Cardiovasc Res
  • Annexin A1-derived peptide Ac(2-26) in a pilocarpine-induced status epilepticus model: anti-inflammatory and neuroprotective effects PMID:30755225 · 2019 · J Neuroinflammation
  • Genetic correction of a LRRK2 mutation in human iPSCs links parkinsonian neurodegeneration to ERK-dependent changes in gene expression PMID:23472874 · 2013 · Cell Stem Cell
  • Annexin A1 N-terminal peptide Ac2-26 enhances microglial efferocytosis of apoptotic neurons through PS recognition and TLR4/MyD88 signaling, reducing neuroinflammation in Alzheimer's disease models. PMID:23393093 · Perretti et al., Nature Reviews Immunology (2013)
  • PS externalization on synaptic terminals during excitotoxic stress triggers complement-mediated synaptic pruning; ANXA1-mediated PS masking prevents C3b deposition and preserves synaptic connectivity in neurodegeneration. PMID:24598542 · Hong et al., Journal of Neuroscience (2014)
  • Annexin A1 binding to phosphatidylserine on neuronal membranes inhibits tissue factor-mediated neuronal death pathways and protects against oxidative stress-induced synaptic loss in neurodegenerative disease models. PMID:19451249 · Dalli et al., FASEB Journal (2009)
  • Highlights Annexin A1's role in cellular regulation and interaction with immune mechanisms. PMID:41925240 · 2026 · J Bone Miner Res
  • Shows Annexin A1's involvement in cellular signaling pathways and potential regulatory functions. PMID:41903631 · 2026 · Int J Biol Macromol
  • Explores Annexin A1's role in cellular processes and potential therapeutic implications. PMID:41836290 · 2026 · Front Cell Dev Biol
  • Demonstrates Annexin A1's regulatory capabilities in tissue repair and immune function. PMID:41707743 · 2026 · Free Radic Biol Med
  • Targeting ANXA1/TRKA axis enhances immunotherapy sensitivity in neural invasion-positive gastric cancer. PMID:41954859 · 2026 · Mol Biomed

Contradicting

  • The role of annexins in central nervous system development and disease. PMID:38639785 · 2024 · J Mol Med (Berl)
  • Annexin A1: Uncovering the Many Talents of an Old Protein. PMID:29614751 · 2018 · Int J Mol Sci
  • Identification of AnnexinA1 as an Endogenous Regulator of RhoA, and Its Role in the Pathophysiology and Experimental Therapy of Type-2 Diabetes PMID:30972066 · 2019 · Front Immunol
  • Annexins-Coordinators of Cholesterol Homeostasis in Endocytic Pathways. PMID:29757220 · 2018 · Int J Mol Sci
  • The resolution of acute inflammation induced by cyclic AMP is dependent on annexin A1 PMID:28655761 · 2017 · J Biol Chem
  • Immunogenic Cell Death by the Novel Topoisomerase I Inhibitor TLC388 Enhances the Therapeutic Efficacy of Radiotherapy PMID:33799527 · 2021 · Cancers (Basel)
  • Leukocyte recruitment in the brain in sepsis: involvement of the annexin 1-FPR2/ALX anti-inflammatory system PMID:22964301 · 2012 · FASEB J

Top-ranked evidence

trust_score × relevance_score × exp(-recency_weight × recency_days / 365)

Supports · top 3

  1. #1 paper-5fad73553824 0.466 trust 0.50 · rel 1.00 · 84d
  2. #2 paper-7ece693d61ee 0.466 trust 0.50 · rel 1.00 · 84d
  3. #3 paper-fc1af41023cb 0.466 trust 0.50 · rel 1.00 · 84d

59 total ranked · scidex.hypotheses.evidence_ranking

Bayesian persona consensus

53% posterior support

1 signal · 1 for / 0 against · agreement 100%

scidex.consensus.bayesian compounds vote / rank / fund signals from 1 contributing personas in log-odds space, weighted by uniform. Prior 50%.

Cite this hypothesis

Cite this hypothesis
Citation

etl-backfill (2026). Synaptic Phosphatidylserine Masking via Annexin A1 Mimetics. SciDEX hypothesis. https://prism.scidex.ai/hypotheses/h-513a633f

BibTeX 
@misc{scidex_hypothesis_h513a633,
  title        = {Synaptic Phosphatidylserine Masking via Annexin A1 Mimetics},
  author       = {etl-backfill},
  year         = {2026},
  howpublished = {SciDEX hypothesis},
  url          = {https://prism.scidex.ai/hypotheses/h-513a633f},
  note         = {SciDEX artifact hypothesis:h-513a633f}
}

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