The TNF-alpha system in heart failure and after heart transplantation: plasma protein levels, mRNA expression, soluble receptors and plasma buffer capacity.
BACKGROUND
The two soluble tumour necrosis factor (TNF) receptors (sTNF-R1, sTNF-R2) can bind TNF-alpha, which is a cytokine with cardiodepressant properties. In heart failure and after heart transplantation, the TNF-alpha system is unbalanced, due to elevated levels of sTNF receptors.


OBJECTIVE
To assess the activity of the TNF-alpha system in patients with heart failure and after heart transplantation.


METHODS
We measured TNF-alpha mRNA expression of peripheral blood mononuclear cells, plasma levels of TNF-alpha and sTNF reverse transcriptase receptors, using polymerase chain reaction and ELISA and performed a TNF-alpha binding capacity analysis, quantitating the buffer capacity of patients' plasma.


RESULTS
In 11 patients with heart failure and in 15 cardiac allograft recipients, the TNF-alpha mRNA expression was comparable to controls. This level of mRNA was not accompanied by detectable TNF-alpha plasma levels. Significantly higher sTNF receptors levels were found in patients: ( P <0.001; ANOVA). The TNF-alpha binding capacity of patients' plasma was significantly increased, which led to decreased TNF-alpha recovery ( P<0.05). Both sTNF receptors showed a linear correlation with serum creatinine (sTNF-RI: r=0.92; sTNF-R2: r=0.82, P<0.001).


CONCLUSIONS
The TNF-alpha mRNA expression and plasma levels show that the 'peripheral' TNF-alpha system is not activated. The high sTNF-receptors levels and their elevated TNF-alpha binding capacity, resulting in decreased TNF-alpha bioavailability, may contribute to an immunosuppressed state in these patients.
D000328:Adult; D000368:Aged; D001682:Biological Availability; D003404:Creatinine / Q000097:blood; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D006333:Heart Failure / Q000378:metabolism*; D016027:Heart Transplantation / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D012333:RNA, Messenger / Q000378:metabolism*; D018124:Receptors, Tumor Necrosis Factor / Q000097:blood / Q000235:genetics / Q000378:metabolism*; D012995:Solubility