Metabolism of glucose and glutamine in lymphocytes from Graves' hyperthyroid patients: influence of methimazole treatment.
Several studies have shown that thyroid hormones are able to influence selected immune responses such as cell mediated immunity, differentiation of B lymphocytes and the activity of NK cells. These hormones can also regulate the metabolism of glucose and glutamine in rat macrophages and their effects seem to occur mainly through the Krebs cycle. Alterations in the hexokinase, citrate synthase, glucose-6-phosphate dehydrogenase and glutaminase activities in lymphocytes from patients with Graves' disease, either untreated or on methimazole (MMI) therapy were investigated. Experiments were also done in vitro to determine the activities of these enzymes in normal lymphocytes cultured for 24 h in the presence of MMI T3 and T4 using concentrations close to the physiological. Changes in the conversion of [U-14C]-glucose and [U-14C]-glutamine to 14CO2 as caused by the addition of MMI, T3 or T4 to the culture medium were also evaluated. The results indicate that high levels of thyroid hormones might stimulate the metabolism of glucose and glutamine for a short period of time but, if the stimulus is maintained, the utilization of glutamine by lymphocytes is then suppressed. Moreover, MMI does affect lymphocyte metabolism but the significance of this finding for its immunosuppressive effect remains to be examined.
Werner
M C
MC
Department of Endocrinology, Hospital do Servidor Público Estadual, IAMSPE, Butantan, Brasil.
Costa Rosa
L F
LF
Romaldini
J H
JH
Curi
R
R
D000328:Adult; D001323:Autoantibodies / Q000097:blood; D002245:Carbon Dioxide / Q000378:metabolism; D002250:Carbon Radioisotopes / Q000378:metabolism; D002478:Cells, Cultured / Q000187:drug effects / Q000201:enzymology; D002950:Citrate (si)-Synthase / Q000378:metabolism; D003470:Culture Media; D005260:Female; D005947:Glucose / Q000378:metabolism*; D005954:Glucosephosphate Dehydrogenase / Q000378:metabolism; D005972:Glutaminase / Q000378:metabolism; D005973:Glutamine / Q000378:metabolism*; D006111:Graves Disease / Q000188:drug therapy / Q000378:metabolism*; D006593:Hexokinase / Q000378:metabolism; D006801:Humans; D008214:Lymphocytes / Q000187:drug effects / Q000201:enzymology*; D008297:Male; D008713:Methimazole / Q000494:pharmacology*; D008875:Middle Aged; D013960:Thyroid Function Tests; D013961:Thyroid Gland / Q000276:immunology / Q000378:metabolism / Q000503:physiopathology; D013974:Thyroxine / Q000494:pharmacology; D014284:Triiodothyronine / Q000494:pharmacology
D001323:Autoantibodies; D002250:Carbon Radioisotopes; D003470:Culture Media; D014284:Triiodothyronine; D005973:Glutamine; D002245:Carbon Dioxide; D008713:Methimazole; D005954:Glucosephosphate Dehydrogenase; D002950:Citrate (si)-Synthase; D006593:Hexokinase; D005972:Glutaminase; D005947:Glucose; D013974:Thyroxine