Hugh C. J. McGregor

Proteomic identification of non-Gal antibody targets after pig-to-primate cardiac xenotransplantation.

Abstract:  Background:  Experience with non‐antigenic galactose α1,3 galactose (αGal) polymers and development of αGal deficient pigs has reduced or eliminated the significance of this antigen in xenograft rejection. Despite these advances, delayed xenograft rejection (DXR) continues to occur most likely due to antibody responses to non‐Gal endothelial cell (EC) antigens.

T‐cell responses during pig‐to‐primate xenotransplantation

Abstract: Xenotransplantation using porcine organs may resolve a chronic shortage of donor organs for clinical transplantation if significant immunological barriers can be overcome. To determine the potential role of T lymphocytes in Xenograft (Xg) rejection, we transplanted transgenic hCD46 porcine hearts heterotopically into baboon recipients. Methods: Recipients were treated to deplete anti‐Gal antibody with a non‐antigenic α‐Gal polyethylene glycol polymer (TPC) (n=2), TPC plus rituximab (anti‐CD20) (n=1) or were untreated (n=1). None of the recipients received T‐cell immunosuppression. Results: All Xgs failed within 7 days and showed evidence of a mixed humoral and cellular rejection process. Cellular infiltration consisting primarily of CD4+ T cells and few CD8+ T cells. Proliferation and cytotoxicity assays showed sensitization of CD4+ and CD8+ T cells that reacted with porcine IFN‐γ (pIFN‐γ)‐stimulated porcine aortic endothelial cells (PAEC). The CD4+ lymphocytes displayed greater cytotoxicity than CD8+ cells. An increased frequency of PAEC‐specific interleukin (IL) 2 and IFN‐γ‐secreting T cells was observed, suggesting a Th1 cytokine bias. An increase in the percentage of circulating CD4+CD28− cells was observed at the time of rejection and over 50% of the CD4+ cells recovered from residual pig tissue at necropsy lacked CD28 expression. Conclusions: These findings show that lymphocytes are efficiently stimulated by PAEC antigens and can mediate direct tissue destruction. These studies (1) provide an insight into the potential of cellular‐mediated cardiac Xg rejection, (2) show for the first time the induction of cytotoxic pig‐specific CD4+CD28− lymphocytes and (3) provide a rational basis for determining different modes of immunosuppression to treat Xg rejection.

T-bet Expression by Dendritic Cells is Required for the Repolarization of Allergic Airway Inflammation

The following article from the European Journal of Immunology, T‐bet expression by dendritic cells is required for the repolarization of allergic airway inflammation by Karin L. Heckman, Suresh Radhakrishnan, Tobias Peikert, Koji Iijima, Hugh C. McGregor, Michael P. Bell, Hirohito Kita and Larry R. Pease published online on 15 September 2008 in Wiley InterScience (www.interscience.wiley.com), has been retracted by agreement between the authors, the journal Editor in Chief, Foo Yoo Liew and Wiley‐VCH. The retraction has been agreed as the results published in the article are unreliable and cannot be reproduced.

X-Ray Crystallography and the Elucidation of the Structure of DNA

OBJECTIVE Since their discovery by Roentgen in 1895, x-rays have contributed to some of the most important advances in science. X-ray crystallography is an imaging technique that uses x-ray diffraction to evaluate the molecular structure of a crystalline solid. This article discusses the critical role played by x-ray crystallography in the elucidation of the structure of DNA. CONCLUSION The story of DNA includes insights on molecular structure provided by x-rays and also lessons on scientific collaboration and innovation that can be applied to radiology today.

Pilot Study of the Safety and Efficacy of Gallbladder Cryoablation in a Porcine Model: Midterm Results

PURPOSE To investigate the midterm safety and efficacy of computed tomography (CT)-guided percutaneous gallbladder cryoablation in swine. MATERIALS AND METHODS Three swine underwent gallbladder cryoablation. Cryoprobes were positioned percutaneously at the gallbladder margins or within the gallbladder lumen under CT guidance. Two freeze/thaw cycles were performed. One animal was euthanized on postprocedure day 4 as a result of hematemesis unrelated to the ablation. The other 2 animals were euthanized at postprocedure days 30 and 48, respectively. The gallbladder and bile ducts were resected and examined microscopically. RESULTS Gallbladder cryoablation was completed with freeze/thaw cycle durations of 7.5-10 minutes (mean, 9.4 min ± 1.3) and ablation margins of 5.8-11.5 mm (mean, 7.8 mm ± 1.9). No nontarget ablation was observed. Laboratory values at postprocedure day 4 and the time of euthanasia were within normal limits. Two of 3 animals thrived and exhibited appropriate activity and weight gain. Contrast-enhanced CT immediately before euthanasia demonstrated delayed linear enhancement of the gallbladder wall. Gross inspection at autopsy revealed fibrotic-appearing gallbladders. Cholecystography revealed no communication to the biliary tree. Histologic examination demonstrated complete gallbladder wall fibrosis. Autopsy of the animal euthanized on day 4 revealed a gastric mucosal ulcer distant from the ablation site with no gastric serosal injury. CONCLUSIONS Gallbladder cryoablation is a promising alternative to surgical cholecystectomy, with complete transmural gallbladder wall fibrosis and cystic duct occlusion seen at 30 and 48 days in swine. Further studies are required to establish procedural safety and long-term efficacy.

Endovascular Biopsy and Endothelial Cell Gene Expression Analysis of Dialysis Arteriovenous Fistulas: A Feasibility Study

PURPOSE To demonstrate feasibility of endothelial cell (EC) biopsy from dialysis arteriovenous fistulas (AVFs) with the use of guidewires and to characterize gene expression differences between ECs from stenotic and nonstenotic outflow vein segments. MATERIALS AND METHODS Nine consecutive patients undergoing fistulography for AVF dysfunction from June to August 2016 were enrolled. ECs were biopsied with the use of guidewires from venous outflow stenoses and control outflow veins central to the stenoses. ECs were sorted with the use of flow cytometry, and the Fluidigm Biomark HD system was used for single-cell quantitative polymerase chain reaction (qPCR) analysis of gene expression. Forty-eight genes were assessed and were selected based on different cellular functions and previous literature. Linear mixed models (LMMs) were used to identify differential gene expression between the groups, and self-organizing maps (SOMs) were used to identify cell clusters based on gene coexpression profiles. RESULTS A total of 219 and 213 ECs were sampled from venous outflow stenoses and control vein segments, respectively. There were no immediate biopsy-related complications. Forty-eight cells per patient were sorted for qPCR analysis. LMM identified 7 genes with different levels of expression at stenotic segments (P < .05), including AGTR-2, HMOX-2, MTHFR, SERPINC-1, SERPINE-1, SMAD-4, and VWF. SOM analysis identified 4 cell clusters with unique gene expression profiles, each containing stenotic and control ECs. CONCLUSIONS EC biopsy from dialysis AVFs with the use of guidewires is feasible. Gene expression data suggest that genes involved in multiple cellular functions are dysregulated in stenotic areas. SOMs identified 4 unique clusters of cells, indicating EC phenotypic heterogeneity in outflow veins.