Protease Activated Receptor-2 and Gastrointestinal Dysfunction in Critical Illness

Study Overview
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Brief Summary
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Gastrointestinal (GI) dysfunction affects up to 50% of medical and surgical critically ill children. GI dysfunction, specifically gastric dysmotility and loss of epithelial barrier integrity, is associated with significant morbidity in critical illness. The mechanisms underlying GI dysfunction in critical illness are not well understood. GI dysfunction in surgery and critical illness has been associated with inflammation. There is evidence to suggest the protease-activated receptor 2 (PAR2) is a link between inflammation and GI dysfunction. PAR2 is a G-coupled receptor present throughout the GI tract. PAR2 mediates GI motility and epithelial barrier integrity. PAR2 is activated by PAR2 agonists, specifically GI serine proteases and zonulin, released under conditions of inflammation. In this study the investigators will examine the relationship between inflammation and PAR2 activation by PAR2 agonists and subsequent GI dysfunction in pediatric critically ill surgical patients. The overall hypothesis of this study is that PAR2 activation by PAR2 agonists, GI serine proteases and zonulin, released due to inflammation results in gastric dysmotility and loss of epithelial barrier integrity. In this study, the investigators will examine whether PAR2 agonist expression is increased and correlates with GI dysfunction in critically ill surgical pediatric patients. This proposal fills a knowledge gap in the understanding of mechanisms for GI dysfunction in critical illness, and will be applicable to all surgical and medical critically ill children.

Detailed Description
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The investigators in this study aim to examine a plausible mechanism by which gastrointestinal dysfunction, gastric dysmotility and loss of epithelial barrier integrity, occur in critical illness. Specifically, the investigators will examine whether an increase in PAR2 agonist levels, zonulin and serine proteases, are associated with gastric dysmotility and loss of epithelial barrier integrity in critical surgical illness in children. The investigators will examine GI function, gastric motility and epithelial barrier integrity, and PAR2 agonist levels, zonulin and serine protease, in participants before surgery and after surgery. Specifically, children undergoing posterior spinal fusion, a known significant inflammatory trigger, and with planned admissions to the intensive care unit will be enrolled. Gastrointestinal function and PAR2 agonist levels will be tested non-invasively in blood and stool.

Official Title
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Examining the Role of Protease-activated Receptor 2 Agonists in Gastrointestinal Dysfunction in Pediatric Surgical Critical Illness

Conditions
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Gastroparesis, Gastrointestinal Disorder, Functional, Critical Illness

Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: 2 years and older Exclusion Criteria: Liver dysfunction Renal dysfunction Pre-diagnosed gastroparesis/ delayed gastric emptying Pre-diagnosed gastrointestinal malabsorption Contraindication to acetaminophen administration

Ages Eligible for Study
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Minimum Age: 2 Years
Maximum Age: 30 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| PAR2 agonist activity- serum zonulin | PAR2 agonist activity will be measured by serum zonulin levels (ng/mL) | Immediately pre-operative versus post-operative day 1 | 
| PAR2 agonist activity- fecal protease activity | PAR2 agonist activity will be measured by fecal serine protease activity (trypsin units/gm protein) | Immediately pre-operative versus post-operative day 1 | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Gastric motility by the acetaminophen absorption test- AUC | Pharmacokinetic parameters of acetaminophen will be used to determined gastric motility including the concentration of acetaminophen at 60 minutes (mcg/mL). | Immediately pre-operative versus post-operative day 1 | 
| Gastric motility by the acetaminophen absorption test- Tmax | Pharmacokinetic parameters of acetaminophen will be used to determined gastric motility including the time to maximum concentration of acetaminophen (minutes). | Immediately pre-operative versus post-operative day 1 | 
| Gastric motility by the acetaminophen absorption test- Cmax | Pharmacokinetic parameters of acetaminophen will be used to determined gastric motility including area under the curve at 60 minutes (mcg*min/mL). | Immediately pre-operative versus post-operative day 1 | 
| Epithelial barrier integrity by serum biomarkers | Epithelial barrier integrity by serum biomarkers, specifically serum zonulin (ng/mL) and lipopolysaccharide binding protein levels (ng/mL). | Immediately pre-operative versus post-operative day 1 | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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pediatric, critical illness, surgery, gastrointestinal dysfunction, gastric emptying, epithelial barrier, nutrition