# A Novel Proteolytic System of Pulmonary Inflammation

> **NIH NIH R01** · UNIVERSITY OF ALABAMA AT BIRMINGHAM · 2021 · $371,250

## Abstract

PROJECT SUMMARY: In what some have described as a paradigm change, we found that the
matrikine proline-glycine-proline (PGP), a collagen derived peptide, regulates neutrophil influx in
chronic lung diseases such as cystic fibrosis (CF). The aims of the previous cycle of this grant
focused on the proteolytic pathway responsible for the generation of PGP and the impact of this
generation system in CF lung disease. The current project examines a novel mechanism of
PGP degradation in CF, a finding rooted in a manuscript in Science, which shows that this
action is carried out by the aminopeptidase activity of leukotriene A4 hydrolase (LTA4H). We
present recent data which demonstrates that the aminopeptidase activity is significantly
reduced, and consequently PGP is increased, in CF lung disease by two discrete mechanisms:
(1) chemical alteration of enzymatic activity by modifications by the reactive aldehyde acrolein
and (2) proteolytic degradation by the serine protease neutrophil elastase (NE). Based on these
findings we propose the following aims: the first will examine the method by which acrolein and
NE inactivate LTA4H aminopeptidase activity, by using mass spectrometry to assess residues
altered by acrolein and cleavage products generated by NE (Aim 1). Next we examine if
bacterial colonization with Pseudomonas aeruginosa, a key pathogen in CF lung disease,
modulates LTA4H aminopeptidase activity and if alterations in LTA4H aminopeptidase function
(by either pharmacologic or genetic methods) impact bacterial colonization (Aim 2). Aim 3
utilizes the beta ENaC overexpressor mouse, a model of the chronic neutrophilic inflammation
observed in CF lung disease. Initial observations demonstrate a progressive accumulation of
PGP peptides as these mice age and in association with a progressive loss of LTA4H
aminopeptidase activity. These mice also demonstrate increased LTB4 levels due to increased
LTA4H epoxy hydrolase activity. For this aim, we will modulate each of these enzymatic
activities by utilizing an epoxy hydrolase specific inhibitor (RS74), a compound to enhance
LTA4H aminopeptidase activity (4-MDM), or both compounds in combination. Aim 4 will focus
on examining PGP levels, as well as LTA4H levels and aminopeptidase activity, in patients
colonized with Pseudomonas aeruginosa. We anticipate the data generated from these aims
will provide clear evidence of a novel host-pathogen interplay, leading to loss of LTA4H
aminopeptidase activity and increased neutrophilic inflammation. The successful completion of
these aims will provide a mechanistic understanding of this dysfunction and new therapeutic
approaches to targeting these pathways in CF lung disease.

## Key facts

- **NIH application ID:** 10085665
- **Project number:** 5R01HL102371-09
- **Recipient organization:** UNIVERSITY OF ALABAMA AT BIRMINGHAM
- **Principal Investigator:** AMIT GAGGAR
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2021
- **Award amount:** $371,250
- **Award type:** 5
- **Project period:** 2010-07-02 → 2022-12-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10085665

## Citation

> US National Institutes of Health, RePORTER application 10085665, A Novel Proteolytic System of Pulmonary Inflammation (5R01HL102371-09). Retrieved via AI Analytics 2026-05-22 from https://api.ai-analytics.org/grant/nih/10085665. Licensed CC0.

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