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Altered caspase expression results in delayed neutrophil apoptosis in acute pancreatitis
S O'Neill1, A J O'Neill, E Conroy
1Department of Surgery, Conway Institute of Biomolecular and Biomedical Research, University College Dublin and Mater Misericordiae Hospital, Ireland.
Abstract:
Acute pancreatitis (AP) may lead to the development of multiple organ dysfunction syndrome (MODS), especially in severe cases. Resolution of such inflammatory responses is dependent on neutrophil apoptosis. Delays in this apoptotic response are associated with persistent inflammation and subsequent tissue damage. The aim of this study is to determine the effects of AP on neutrophil apoptosis and to investigate the underlying mechanisms involved. Neutrophils and serum were isolated from control (n=10) and from patients with AP (mild, n=35, and severe, n=5). Neutrophil apoptosis was assessed by propidium iodide DNA staining using flow cytometry. Caspase, glutathione-S-transferase (GST), and Mcl-1 protein expression were assessed by SDS-PAGE western blotting. Serum interleukin (IL)-1beta and granulocyte-macrophage colony-stimulating factor (GM-CSF) levels were measured by ELISA. Neutrophils isolated from patients with AP show a significant delay in spontaneous neutrophil apoptosis. Serum factors contributed to this delay with increases in IL-1beta and GM-CSF. Isolated neutrophils were resistant to Fas antibody-induced apoptosis. Caspases represent a central mechanism for spontaneous and Fas antibody-induced neutrophil apoptosis. Procaspase 3 expression was decreased in mild and severe cases, but this effect was independent of serum factors. Increases in GST expression may also contribute to the antiapoptotic effect. Altered caspase expression may represent an additional factor contributing to delayed neutrophil apoptosis. This may contribute to the development of AP and its related complications.
Insights
Acute pancreatitis delays neutrophil apoptosis, prolonging inflammation and tissue damage. This delay is linked to increased serum factors and altered caspase expression, potentially worsening pancreatitis complications.
Area of Science:
- Immunology
- Gastroenterology
- Cell Biology
Background:
- Acute pancreatitis (AP) can lead to multiple organ dysfunction syndrome (MODS).
- Resolution of inflammation in AP relies on timely neutrophil apoptosis.
- Delayed neutrophil apoptosis is associated with persistent inflammation and tissue damage.
Purpose of the Study:
- To determine the impact of AP on neutrophil apoptosis.
- To investigate the molecular mechanisms underlying altered neutrophil apoptosis in AP.
- To explore the role of serum factors and protein expression in AP-induced neutrophil apoptosis.
Main Methods:
- Isolation of neutrophils and serum from control and AP patients (mild and severe).
- Assessment of neutrophil apoptosis using propidium iodide DNA staining and flow cytometry.
- Measurement of caspase, glutathione-S-transferase (GST), and Mcl-1 protein expression via SDS-PAGE western blotting.
- Quantification of serum interleukin (IL)-1beta and granulocyte-macrophage colony-stimulating factor (GM-CSF) using ELISA.
Main Results:
- Neutrophils from AP patients exhibited significantly delayed spontaneous apoptosis.
- Elevated serum IL-1beta and GM-CSF levels correlated with delayed apoptosis.
- Neutrophils showed resistance to Fas antibody-induced apoptosis.
- Decreased procaspase 3 expression was observed in AP, independent of serum factors.
- Increased GST expression may contribute to the antiapoptotic effect.
Conclusions:
- AP significantly delays neutrophil apoptosis, mediated by serum factors like IL-1beta and GM-CSF.
- Altered caspase expression, particularly decreased procaspase 3, is a key mechanism contributing to delayed apoptosis in AP.
- These findings suggest that impaired neutrophil apoptosis plays a crucial role in the pathogenesis and complications of acute pancreatitis.