# Cell-penetrating botulinum proteases as topical therapeutics

> **NIH NIH R21** · UNIVERSITY OF CALIFORNIA-IRVINE · 2024 · $172,700

## Abstract

ABSTRACT
The importance of communications between nerve cells and immune cells in skin has been increasingly
recognized, as are the contributions of sensory neurons and the neuropeptides they produce to skin inflammation
and disease. Topical therapeutics that target neuro-immune interactions are needed to curtail aberrant skin
inflammation in diseases such as psoriasis and atopic dermatitis and to alleviate the disease-associated
pathology, pain, and itch. Our ongoing research aims to develop effective topical options to complement systemic
immune-targeting biologics, providing targeted relief and improving patient outcomes. The goals of this
application are to develop recombinant, cell-penetrating botulinum proteases that inhibit the release of
neuropeptides and cytokines in neurons and immune cells, respectively, to examine the in vivo penetration of
topically applied proteases into skin with mild barrier perturbation, and to test the utility of the engineered
proteases in reducing skin inflammation. Botulinum neurotoxins (BoNTs), such as Botox®, have been widely
used in clinics as medicines and cosmetics. BoNT specifically targets motor neurons and deliver its light chain
(LC) protease to the cytosol, where it proteolytically cleaves SNARE (soluble N-ethylmaleimide sensitive factor
attachment protein receptors) proteins and blocks neurotransmitter release. Prior studies also suggest that
BoNTs are able to suppress neuropeptide secretion, such as substance P (SP) and calcitonin gene-related
peptide (CGRP), in the skin via disrupting SNARE-mediated vesicle fusion and lead to improvement of
inflammation in psoriasis. However, the therapeutic potential of conventional BoNTs in psoriasis is inherently
restricted because BoNTs preferentially target motor neurons over sensory neurons and they are ineffective on
immune cells. To overcome these limitations, we have engineered recombinant cell-penetrating LC proteases of
BoNT that can autonomously enter cells and selectively cleave SNAREs in sensory neurons and/or immune
cells to regulate neuropeptide secretion and immunological effects. Here, we propose to further develop and
characterize cell-penetrating LC proteases and examine how they inhibit vesicle fusion and secretion in cultured
neurons and immune cells (Aim 1). We will also characterize the activity of the engineered LC variants in mouse
skin with topical delivery and perform preclinical studies to examine how topically applied LCs affect skin
inflammatory response using mouse models of psoriasis (Aim 2). Completion of this work will result in a new and
widely-applicable strategy to regulate inflammation in skin that can be further developed as topical therapeutic
candidates for the treatment of many skin diseases.

## Key facts

- **NIH application ID:** 10887823
- **Project number:** 1R21AR084252-01
- **Recipient organization:** UNIVERSITY OF CALIFORNIA-IRVINE
- **Principal Investigator:** Xing Dai
- **Activity code:** R21 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2024
- **Award amount:** $172,700
- **Award type:** 1
- **Project period:** 2024-08-20 → 2026-07-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10887823

## Citation

> US National Institutes of Health, RePORTER application 10887823, Cell-penetrating botulinum proteases as topical therapeutics (1R21AR084252-01). Retrieved via AI Analytics 2026-05-26 from https://api.ai-analytics.org/grant/nih/10887823. Licensed CC0.

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