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A nanoconjugate Apaf-1 inhibitor protects mesothelial cells from cytokine-induced injury
Beatriz Santamaría1, Alberto Benito-Martin, Alvaro Conrado Ucero
1Dialysis Unit, Fundación Jiménez Díaz, Universidad Autónoma de Madrid, Instituto Reina Sofía de Investigación Nefrológica, Madrid, Spain.
Background:
Inflammation may lead to tissue injury. We have studied the modulation of inflammatory milieu-induced tissue injury, as exemplified by the mesothelium. Peritoneal dialysis is complicated by peritonitis episodes that cause loss of mesothelium. Proinflammatory cytokines are increased in the peritoneal cavity during peritonitis episodes. However there is scarce information on the modulation of cell death by combinations of cytokines and on the therapeutic targets to prevent desmesothelization.
Methodology:
Human mesothelial cells were cultured from effluents of stable peritoneal dialysis patients and from omentum of non-dialysis patients. Mesothelial cell death was studied in mice with S. aureus peritonitis and in mice injected with tumor necrosis factor alpha and interferon gamma. Tumor necrosis factor alpha and interferon gamma alone do not induce apoptosis in cultured mesothelial cells. By contrast, the cytokine combination increased the rate of apoptosis 2 to 3-fold over control. Cell death was associated with the activation of caspases and a pancaspase inhibitor prevented apoptosis. Specific caspase-8 and caspase-3 inhibitors were similarly effective. Co-incubation with both cytokines also impaired mesothelial wound healing in an in vitro model. However, inhibition of caspases did not improve wound healing and even impaired the long-term recovery from injury. By contrast, a polymeric nanoconjugate Apaf-1 inhibitor protected from apoptosis and allowed wound healing and long-term recovery. The Apaf-1 inhibitor also protected mesothelial cells from inflammation-induced injury in vivo in mice.
Conclusion:
Cooperation between tumor necrosis factor alpha and interferon gamma contributes to mesothelial injury and impairs the regenerative capacity of the monolayer. Caspase inhibition attenuates mesothelial cell apoptosis but does not facilitate regeneration. A drug targeting Apaf-1 allows protection from apoptosis as well as regeneration in the course of inflammation-induced tissue injury.
Insights
Tumor necrosis factor alpha and interferon gamma induce mesothelial cell death during inflammation. Targeting Apaf-1 protects cells and promotes tissue regeneration, unlike caspase inhibitors.
Area of Science:
- Cell biology
- Immunology
- Tissue engineering
Background:
- Inflammation can cause tissue injury, exemplified by mesothelial cells.
- Peritoneal dialysis complications include peritonitis, leading to mesothelial cell loss.
- Proinflammatory cytokines increase during peritonitis, but their combined effects on cell death and therapeutic targets are poorly understood.
Purpose of the Study:
- To investigate the combined effects of tumor necrosis factor alpha and interferon gamma on mesothelial cells.
- To identify therapeutic targets for preventing inflammation-induced mesothelial cell injury and loss.
- To evaluate the role of caspases and Apaf-1 in mesothelial cell apoptosis and regeneration.
Main Methods:
- Cultured human mesothelial cells from peritoneal dialysis patients and non-dialysis patients.
- Induced peritonitis in mice using S. aureus and administered tumor necrosis factor alpha and interferon gamma.
- Assessed mesothelial cell death, apoptosis, caspase activation, wound healing in vitro, and in vivo protection using specific inhibitors.
Main Results:
- Tumor necrosis factor alpha and interferon gamma synergistically increased mesothelial cell apoptosis 2-3 fold.
- Caspase inhibitors (pancaspase, caspase-8, caspase-3) prevented apoptosis but impaired wound healing.
- An Apaf-1 inhibitor protected mesothelial cells from apoptosis and promoted wound healing and long-term recovery in vitro and in vivo.
Conclusions:
- Combined tumor necrosis factor alpha and interferon gamma induce mesothelial injury and impair regeneration.
- Caspase inhibition reduces apoptosis but hinders tissue regeneration.
- Targeting Apaf-1 offers a dual benefit of preventing apoptosis and facilitating regeneration during inflammation-induced tissue injury.
