Small intestinal submucosa induces loss of mitochondrial integrity and caspase-dependent apoptosis in human T cells.
Porcine small intestinal submucosa (SIS) is a cell-free biomaterial used in humans for wound healing and as scaffold material for constructive remodeling of damaged or missing tissue. We have previously shown that SIS contains a factor that suppresses human helper T cell subset differentiation and expansion by inducing programmed cell death. Our aims here were to identify in detail the processes involved in SIS-induced T cell apoptosis and to perform the first characterization of the apoptosis-inducing factor present in SIS. In in vitro experiments, we utilized human T cell lines, Jurkat and CEM, to identify the processes involved in SIS-induced T cell apoptosis. Two types of sterile SIS material were used: hydrated sheets and rehydrated clinical-grade sheets. We found that SIS-mediated apoptosis as detected by induction of membrane annexin V staining involved the loss of mitochondrial membrane potential and was dependent on caspase activation. We eliminated transforming growth factor beta (TGF-beta), Fas ligand (FasL), and galectin family members as factors in SIS-mediated T cell apoptosis. We further established that processes required to prepare SIS for clinical use, freeze-drying, and gas sterilization destroyed the apoptosis-inducing factor. SIS contains a factor that induces loss of mitochondrial integrity and caspase-dependent apoptosis in human T cells. This factor is destroyed by freeze-drying and gas sterilization and is not TGF-beta, FasL, or a galectin family member. Normal T cell homeostasis in gut-associated tissues may be regulated in part by this unknown factor.
Department of Environmental Health, Boston University School of Public Health, Boston, Massachusetts 02118, USA.
E M
EM
Palmer
L G
LG
Baum
G A
GA
van Seventer
D000818:Animals; D017304:Annexin A5 / Q000032:analysis; D017209:Apoptosis / Q000187:drug effects*; D001672:Biocompatible Materials / Q000737:chemistry / Q000494:pharmacology*; D001685:Biological Factors / Q000494:pharmacology*; D015496:CD4-Positive T-Lymphocytes / Q000187:drug effects* / Q000201:enzymology / Q000648:ultrastructure; D020169:Caspases / Q000502:physiology; D002460:Cell Line / Q000187:drug effects; D005109:Extracellular Matrix / Q000737:chemistry*; D005612:Freeze Drying; D006133:Growth Substances / Q000032:analysis; D006801:Humans; D007421:Intestine, Small / Q000033:anatomy & histology* / Q000737:chemistry; D007425:Intracellular Membranes / Q000187:drug effects / Q000502:physiology; D019169:Jurkat Cells / Q000187:drug effects; D008422:Materials Testing; D008564:Membrane Potentials / Q000187:drug effects; D008928:Mitochondria / Q000187:drug effects / Q000502:physiology / Q000648:ultrastructure; D013242:Sterilization; D013552:Swine
D017304:Annexin A5; D001672:Biocompatible Materials; D001685:Biological Factors; D006133:Growth Substances; D020169:Caspases