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TNF-alpha, IL-4, and IFN-gamma regulate differential expression of P- and E-selectin expression by porcine aortic
C J Stocker1, K L Sugars, O A Harari
1British Heart Foundation Cardiovascular Medicine Unit, and Department of Medicine, Imperial College School of Medicine, Hammersmith Hospital, London, United Kingdom.
Insights
Porcine aortic endothelial cells show differential regulation of P- and E-selectin expression. Interleukin-4 shifts this balance toward P-selectin, impacting inflammation in xenografts.
Area of Science:
- Immunology
- Cell Biology
- Biochemistry
Background:
- P-selectin and E-selectin are crucial glycoproteins mediating leukocyte-endothelial cell interactions during inflammation.
- Understanding their differential regulation is key to modulating inflammatory responses.
Purpose of the Study:
- To investigate the differential expression and regulation of P-selectin and E-selectin in porcine aortic endothelial cells (PAECs).
- To explore the role of cytokines, including IL-4 and IFN-gamma, in modulating selectin expression.
Main Methods:
- Cloning of porcine P-selectin cDNA.
- Generation of a monoclonal antibody (mAb) 12C5 for P-selectin detection.
- Stimulation of PAECs with various cytokines (TNF-alpha, IL-1alpha, IL-4, IFN-gamma) and assessment of P- and E-selectin expression.
Main Results:
- PAECs exhibited higher basal P-selectin than E-selectin expression.
- TNF-alpha and IL-1alpha more significantly enhanced E-selectin than P-selectin expression.
- IL-4 (human or porcine) increased P-selectin expression with delayed kinetics, but not E-selectin.
- IL-4 stimulation in the presence of TNF-alpha enhanced P-selectin while reducing E-selectin expression.
- Porcine IFN-gamma inhibited IL-4-induced P-selectin expression, while human IFN-gamma did not.
Conclusions:
- P-selectin and E-selectin expression are distinctly regulated in PAECs.
- IL-4 induces a shift towards higher P-selectin surface density.
- The balance of Th1/Th2 cytokines, influenced by IFN-gamma, likely dictates selectin expression in chronic inflammation.
- Differential cytokine effects suggest a shift towards P-selectin in porcine xenografts with human lymphocyte infiltration.
Abstract:
P- and E-selectin are surface glycoproteins that mediate leukocyte rolling on the surface of endothelium in inflammation. We have cloned porcine P-selectin cDNA and generated a mAb, 12C5, with which to examine P-selectin expression by porcine aortic endothelial cells (PAEC) in comparison with that of E-selectin. Basal expression by PAEC of P-selectin was greater than that of E-selectin, whereas E-selectin expression was more prominently enhanced than that of P-selectin by stimulation with TNF-alpha or IL-1alpha. Both human or porcine IL-4 led to an increase in P-selectin expression, with kinetics that were delayed compared with those seen following stimulation with TNF-alpha or IL-1alpha, but IL-4 did not stimulate expression of E-selectin. When cells were stimulated with TNF-alpha in the presence of IL-4, we observed enhanced P-selectin expression with a parallel reduction in E-selectin expression. Finally, the increase in P-selectin expression due to human IL-4 was reduced in the presence of porcine but not human IFN-gamma. These observations show that E-selectin and P-selectin expression are differentially regulated in PAEC, and that IL-4 leads to a shift in the relative surface density of the two molecules toward P-selectin. The ability of porcine IFN-gamma to inhibit IL-4-induced P-selectin expression suggests that the balance between Th1 and Th2 cytokine production may determine the relative densities of the two selectins in chronic immune-mediated inflammation. Because the increased expression of P-selectin induced by human IL-4 was not inhibited by human IFN-gamma, this balance may be shifted toward P-selectin expression in porcine xenografts infiltrated by human lymphocytes.