Effect of 2,4-diamino-6-hydroxy-pyrimidine on postburn Staphylococcus aureus sepsis in rats.
OBJECTIVE
Guanosine triphosphate-cyclohydrolase I (GTP-CHI) is the first and rate-limiting enzyme for the de novo biosynthesis of biopterin. The objective of present study was to observe the effect of 2,4-diamino-6-hydroxy-pyrimidine (DAHP), an inhibitor of GTP-CHI, on the development of postburn Staphylococcus aureus sepsis.


METHODS
A prospective, controlled animal study.


METHODS
A research laboratory in a hospital.


METHODS
Male Wistar rats.


METHODS
Fifty-six male Wistar rats were randomly divided into four groups as follows: normal control group (n = 10), scald control group (n = 10), postburn sepsis group (n = 20), and DAHP treatment group (n = 16). In the scald control group, rats were subjected to a 20% total body surface area third-degree scald injury and then were killed at 24 hrs. In the postburn sepsis group (n = 20), rats were inflicted with 20% total body surface area third-degree scald followed by Staphylococcus aureus challenge, and they were further divided into 2- and 6-hr groups. In the DAHP treatment group (n = 16), animals were intraperitoneally injected with a dose of 1 g/kg DAHP before Staphylococcus aureus challenge and then were further divided into 2- and 6-hr groups. Tissue samples from liver, kidneys, lungs, and heart were collected to determine GTP-CHI, inducible nitric oxide synthase, and tumor necrosis factor-alpha messenger RNA expression. Meanwhile, biopterin and nitric oxide concentrations in these tissues were also measured.


RESULTS
After the scald injury followed by Staphylococcus aureus challenge, GTP-CHI messenger RNA expression and biopterin concentrations were significantly elevated in various tissues such as liver, heart, kidneys, and lungs, as were the values of inducible nitric oxide synthase messenger RNA expression and nitric oxide formation (p <.01). Pretreatment with DAHP significantly reduced GTP-CHI/biopterin induction (p <.05-.01), and the up-regulation of inducible nitric oxide synthase/nitric oxide was also suppressed. Furthermore, DAHP administration inhibited the gene expression of tumor necrosis factor-alpha. Two hours after septic challenge, tumor necrosis factor-alpha messenger RNA expression in liver, kidneys, and lungs in the DAHP-treated group was 35.7%, 37.3%, and 33.0% of that in the postburn septic group, respectively. Additionally, in animals without DAHP treatment, the 6-hr mortality rate was 55.6% (20 of 36), whereas it was only 25.0% in DAHP-treated animals (4 of 16, p =.08).


CONCLUSIONS
Early treatment with DAHP might be a potential strategy to prevent the development of postburn Staphylococcal sepsis, which appears to be associated with down-regulation of biopterin and nitric oxide formation by DAHP.
Li
Hong-Yun
HY
Department of Microbiology and Immunology, Trauma Research Center, Postgraduate Medical College, 304th Hospital, Beijing, People's Republic of China.
Yao
Yong-Ming
YM
Shi
Zhi-Guo
ZG
Dong
Ning
N
Yu
Yan
Y
Lu
Lian-Rong
LR
Sheng
Zhi-Yong C Y
ZY
D000704:Analysis of Variance; D000818:Animals; D001708:Biopterins / Q000031:analogs & derivatives* / Q000096:biosynthesis; D002056:Burns / Q000382:microbiology*; D015536:Down-Regulation / Q000187:drug effects; D004791:Enzyme Inhibitors / Q000494:pharmacology / Q000627:therapeutic use*; D006136:GTP Cyclohydrolase / Q000037:antagonists & inhibitors*; D007042:Hypoxanthines / Q000494:pharmacology / Q000627:therapeutic use*; D008297:Male; D009569:Nitric Oxide / Q000096:biosynthesis; D019001:Nitric Oxide Synthase / Q000096:biosynthesis; D011446:Prospective Studies; D012333:RNA, Messenger / Q000378:metabolism; D011897:Random Allocation; D051381:Rats; D017208:Rats, Wistar; D018805:Sepsis / Q000209:etiology / Q000382:microbiology / Q000517:prevention & control*; D013203:Staphylococcal Infections / Q000209:etiology / Q000517:prevention & control*
D004791:Enzyme Inhibitors; D007042:Hypoxanthines; D012333:RNA, Messenger; D001708:Biopterins; D009569:Nitric Oxide; D019001:Nitric Oxide Synthase; D006136:GTP Cyclohydrolase; C017202:2,4-diaminohypoxanthine; C003402:sapropterin