Related Experiment Videos
Experimental induction and ultrastructural characterization of apoptosis in murine acute cutaneous graft-versus-host
Y H Yoo1, A C Gilliam, D Whitaker-Menezes
1Department of Anatomy and Cell Biology, Dong-A University College of Medicine, Pusan, South Korea. yhyoo@seunghak.donga.ac.kr
Abstract:
The skin is a primary target organ in acute graft-versus-host disease (GVHD). Recent results suggest that keratinocytes may undergo apoptosis in acute GVHD, although sequential structural evidence supporting this concept is lacking. The present study was undertaken to document and characterize apoptosis, confirmed by endonuclease-mediated DNA fragmentation, in experimental acute GVHD via sequential analysis of ultrastructure. Furthermore, we sought to define whether apoptosis is effector cell-dependent or- independent, and to document cell types responsible for the scavenging of apoptotic cells. Acute GVHD was produced across minor histocompatibility loci using appropriately matched murine strains and highly purified preparations of donor CD4+ and CD8+ T-cell subsets. Transmission electron microscopy was correlated with in situ labeling of double-stranded DNA breaks by the TUNEL (terminal uridine deoxynucleotidyl transferase end ligation) technique. Apoptotic cells were observed in all groups receiving T cells. Although most apoptotic cells were found in apposition with effector lymphocytes, a minority of apoptotic cells were detected at early time-points prior to lymphocytic infiltration. Heterogeneous cells, including macrophages, lymphocytes, Langerhans cells and keratinocytes were involved in scavenging putative target cells undergoing apoptosis. This study confirms the final pathway of target cell injury in acute GVHD to be apoptosis. In acute GVHD, apoptosis can be induced in the presence or absence of local effector cell influx, suggesting at least two mechanisms for the induction of epidermal target cell injury.
Insights
Skin cells undergo programmed cell death (apoptosis) in acute graft-versus-host disease (GVHD). This study confirms apoptosis as the primary injury pathway, occurring with or without direct immune cell contact.
Area of Science:
- Immunology
- Dermatology
- Cell Biology
Background:
- Skin is a key target in acute graft-versus-host disease (GVHD).
- Previous research suggested keratinocyte apoptosis in GVHD, but lacked sequential structural evidence.
- The precise mechanisms and cell types involved in GVHD-induced skin cell death require further elucidation.
Purpose of the Study:
- To structurally document and characterize apoptosis in experimental acute GVHD.
- To determine if apoptosis induction is effector cell-dependent or independent.
- To identify the cell types responsible for clearing apoptotic cells in GVHD.
Main Methods:
- Acute GVHD was induced in mice across minor histocompatibility loci.
- Highly purified donor CD4+ and CD8+ T-cell subsets were used.
- Transmission electron microscopy and TUNEL (terminal uridine deoxynucleotidyl transferase end ligation) staining were employed for ultrastructural analysis and DNA fragmentation detection.
Main Results:
- Apoptotic cells were consistently observed in GVHD models receiving T cells.
- While most apoptotic cells were near effector lymphocytes, some appeared before significant immune cell infiltration.
- Macrophages, lymphocytes, Langerhans cells, and keratinocytes were identified as scavengers of apoptotic cells.
Conclusions:
- Apoptosis is confirmed as the terminal pathway of target cell injury in acute GVHD.
- Epidermal cell apoptosis in GVHD can be induced both with and without direct effector cell contact, suggesting dual mechanisms.
- Understanding these mechanisms is crucial for developing targeted therapies for GVHD skin manifestations.