Treatment with antithymocyte globulin ameliorates intestinal ischemia and reperfusion injury in mice

Antithymocyte therapy, specifically antithymocyte globulin (ATG; Thymoglobulin), is increasingly being used in organ transplantation to reduce allograft rejection. The T-lymphocyte has been purported to also play a role in ischemia and reperfusion injury (IRI); however, it has not been well studied. Our aim is to determine if ATG treatment impacts murine intestinal IRI.

Under anesthesia, male C57BL6 mice underwent 100 minutes of warm intestinal IRI by clamping the superior mesenteric artery. The treatment group received rabbit anti-murine ATG (10 mg/kg) intraperitoneally 6 hours before IRI. Separate survival and analysis groups were performed. Intestinal tissue was procured at 4 and 24 hours after IRI. Tissue analysis included hematoxylin-eosin staining, CD3, CD4, and CD8 immunostaining, myeloperoxidase assay (MPO), quantitative real-time polymerase chain reaction studies, and Western blot.

ATG treatment led to marked improvement in 7-day survival and a reduction in tissue injury by histology. MPO was also reduced, and immunostaining confirmed a significant reduction in CD3(+), CD4(+), and CD8(+) infiltrating cells in the treatment group. Quantitative real-time polymerase chain reaction analysis revealed the decreased expression of tumor necrosis factor-α, interferon-inducible protein 10, monocyte chemotactic protein-1, interferon-γ, interleukin-2, and increased production of interleukins -13 and -10 in the treatment group. Western blot analysis revealed decreased caspase-3 and increased signal transducer and activator of transcription 6 levels in the ATG-treated group.

This study is the first to show that ATG treatment ameliorates intestinal IRI. Treatment with ATG leads to reduced local infiltration by T-lymphocytes, with fewer inflammatory and chemotactic programs and less apoptosis. Treatment also is associated with a T(H)2-type cytokine switch. These novel findings suggest that T-lymphocytes represent important mediators of intestinal IRI and that ATG therapies may be beneficial in the prevention of IRI.