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Cardiac myocyte-specific overexpression of human GTP cyclohydrolase I protects against acute cardiac allograft rejection. Am J Physiol Heart Circ Physiol 2010 Jul;299(1):H88-96



Pubmed ID


Pubmed Central ID




Scopus ID

2-s2.0-77953745147   6 Citations


GTP cyclohydrolase I (GTPCH) is the rate-limiting enzyme for tetrahydrobiopterin (BH(4)) synthesis. Decreases in GTPCH activity and expression have been shown in late stages of acute cardiac rejection, suggesting a deficit in BH(4). We hypothesized that increasing intracellular levels of BH(4) by cardiac myocyte-targeted overexpression of GTPCH would diminish acute cardiac allograft rejection. Transgenic mice overexpressing GTPCH in the heart were generated and crossed on C57BL6 background. Wild-type and transgenic mouse donor hearts were transplanted into BALB/c recipient mice. Left ventricular (LV) function, histological rejection, BH(4) levels, and inflammatory cytokine gene expression (mRNA) were examined. Expression of human GTPCH was documented by PCR, Western analysis, and function by a significant (P < 0.001) increase in cardiac BH(4) levels. GTPCH transgene decreased histological rejection (46%; P < 0.003) and cardiac myocyte injury (eosin autofluorescence; 56%; P < 0.0001) independent of changes in inflammatory cytokine expression or nitric oxide content. GTPCH transgene decreased IL-2 (88%; P < 0.002), IL-1R2 (42%; P < 0.0001), and programmed cell death-1 (67%; P < 0.0001) expression, whereas it increased fms-like tyrosine kinase 3 (156%; P < 0.0001) and stromal-derived factor-1 (2; 190%; P < 0.0001) expression. There was no difference in ejection fraction or fractional shortening; however, LV mass was significantly increased (P < 0.05) only in wild-type grafts. The decreases in LV mass, cardiac injury, and histological rejection support a protective role of cardiac GTPCH overexpression and increased BH(4) synthesis in cardiac allografts. The mechanism of the decreased rejection appears related to decreased T cell proliferation and modulation of immune function by higher expression of genes involved in hematopoietic/stromal cell development and recruitment.

Author List

Ionova IA, Vásquez-Vivar J, Cooley BC, Khanna AK, Whitsett J, Herrnreiter A, Migrino RQ, Ge ZD, Regner KR, Channon KM, Alp NJ, Pieper GM


Kevin R. Regner MD Chief, Professor in the Medicine department at Medical College of Wisconsin
Jeannette M. Vasquez-Vivar PhD Professor in the Biophysics department at Medical College of Wisconsin

MESH terms used to index this publication - Major topics in bold

Acute Disease
GTP Cyclohydrolase
Graft Rejection
Heart Transplantation
Inflammation Mediators
Mice, Inbred BALB C
Mice, Inbred C57BL
Mice, Transgenic
Myocytes, Cardiac
Nitric Oxide
RNA, Messenger
Transplantation, Homologous
Ventricular Function, Left