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Correlation between mononuclear infiltration and changes in VASP phosphorylation patterns after heterotopic cardiac
T Deuse1, V Lange, S Schrepfer
1Clinic of Heart and Thoracic Surgery, Julius Maximilian University, Würzburg, Germany.
Insights
Platelet VASP phosphorylation patterns change during cardiac allograft perfusion, correlating with immune cell infiltration. This finding highlights the impact of infiltrating cells on graft health and potential therapeutic targets.
Area of Science:
- Cardiovascular Research
- Immunology
- Cell Biology
Background:
- Chronic cardiac transplant vasculopathy is a primary cause of late graft failure.
- Inducible nitric oxide synthase (iNOS) is implicated in vasculopathy progression.
- Vascular cell adhesion molecule-1 (VASP) phosphorylation is modulated by cyclic nucleotide-dependent protein kinases.
Purpose of the Study:
- To investigate the correlation between platelet VASP phosphorylation (VASP shift) after coronary passage of rat cardiac allografts and graft infiltration.
- To explore the role of iNOS in modulating platelet VASP phosphorylation during cardiac rejection.
Main Methods:
- Utilized a heterotopic rat cardiac transplantation model (Lew-F344).
- Harvested native hearts and grafts for Langendorff perfusion to assess platelet VASP phosphorylation.
- Employed immunohistology to quantify graft mononuclear infiltration.
- Pharmacologically modulated iNOS activity.
Main Results:
- Platelet VASP Ser(157) and Ser(239) phosphorylation significantly increased post-coronary perfusion of native hearts and grafts.
- A significant correlation was observed between changes in platelet VASP shift and graft mononuclear infiltration, particularly after iNOS inhibition.
- Platelet VASP shift modification during perfusion reflects underlying graft infiltration.
Conclusions:
- Platelet VASP phosphorylation patterns are altered during coronary perfusion of cardiac allografts.
- These alterations correlate with the extent of mononuclear cell infiltration within the graft.
- The findings suggest a link between immune cell infiltration and cytoskeletal changes in adjacent cells, impacting graft integrity.
Abstract:
Chronic cardiac transplant vasculopathy still remains the major cause of late graft failure after the 1st postoperative year, with iNOS playing a central role in the progression of this disease. Since VASP, a recently identified microfilament-associated protein in smooth muscle cells, endothelial cells, and platelets, is phosphorylated by cyclic nucleotide dependent protein kinases, changing amounts of NO-producing mononuclear infiltration cells during cardiac rejection are supposed to change platelet VASP phosphorylation patterns. We investigated whether platelet VASP Ser(157) phosphorylation (VASP shift) after coronary passage of rat cardiac allografts correlates with graft infiltration. The Lew-F344 heterotopic rat cardiac transplantation model was used. Native hearts and grafts were harvested 3-150 days after transplantation and were used for Langendorff perfusion. The platelet VASP shift after native heart and graft perfusion was identified. Additional iNOS stimulation and iNOS inhibition were achieved pharmacologically. Immunohistology revealed graft mononuclear infiltration. Platelet VASP Ser(157) and Ser(239) phosphorylation significantly increased after coronary passage of native hearts and grafts (p < 0.01). Though platelet VASP Ser(157) phosphorylation failed to directly express graft infiltration, we showed a significant correlation between changes of platelet VASP shift and extent of grafts' mononuclear infiltration after competitive iNOS inhibition (p < 0.01). The platelet VASP shift is modified during coronary perfusion, and this modification correlates with mononuclear infiltration in the graft. This emphasizes the influence of mononuclear infiltration cells on microfilamental structures of the cytoskeleton in adjacent cells.