Method for the determination of the formation of endothelins for medical diagnostic purposes, and antibodies and kits for carrying out such a method
The invention relates to an in vitro method for detecting the formation of endothelins during serious illnesses, especially cardiovascular diseases, inflammations, sepsis and cancer, in whole blood, plasma or serum of a human patient for medical diagnosis. Using this method, relatively long-lasting peptide fragments, especially a C-terminal peptide fragment, of the processed primary prepro- or proendothelins that contain neither the actual biologically active endothelin nor its direct precursor, big endothelin, can be detected.
1. An in vitro method for the determination of the formation of endothelins in a human patient suspected of a disease selected from the group consisting of cardiovascular disease, and sepsis, wherein the formation of endothelin-1 (SEQ ID NO.:2) and big endothelin-1 (SEQ ID NO.: 3) is determined by detecting a C-terminal fragment of preproendothelin-1 (SEQ ID NO.: 1), the method comprising:
obtaining a whole blood, plasma or serum sample from the patient;
contacting said sample with first antibodies that specifically bind to a first peptide within amino acids 168-212 of preproendothelin-1 (SEQ ID NO.: 1) and second antibodies that specifically bind to a second peptide within amino acids 168-212 of preproendothelin-1, one of said first and second antibodies being labeled with a detectable marker, wherein the level of said C-terminal fragment detected by said first and second antibodies correlates with the level of formation of endothelin-1 (SEQ ID NO:2) or big endothelin-1 (SEQ ID NO:3) in said patient.
2. The method of claim 1 , wherein said first and second antibodies bind to two different peptides of preproendothelin-1 selected from peptides consisting of amino acids 168-181, 184-203 and 200-212 of preproendothelin-1.
3. The method of claim 1 , wherein said method provides for the quantitative or semiquantitative determination of the C-terminal fragment of preproendothelin-1 comprising amino acids 168-212 of preproendothelin-1.
4. The method as claimed in claim 3 , wherein said determination is an immunochromatographic point-of-care test.
5. The method as claimed in claim 1 , wherein the first and second antibodies used for the determination are selected from monoclonal antibodies, affinity-purified polyclonal antibodies, or a combination of monoclonal and affinity-purified antibodies.
6. The method as claimed in claim 1 , wherein the first and second antibodies are obtained by immunizing an animal with a synthetic peptide consisting of amino acids 168-181, 184-203 or 200-212 of preproendothelin-1.
7. The method as claimed in claim 1 , wherein one of said first and second antibodies is bound to a solid phase.
8. The method as claimed in claim 1 , wherein said first and second antibodies are present in dispersed form in a liquid reaction mixture, a first detectable marker being bound to the first antibody, and a second detectable marker being bound to the second antibody so that, after binding of both antibodies to the terminal fragment of preproendothelin-1 to be detected to form an analyte/antibody complex, a measurable signal which permits detection of the complexes in the measuring solution is generated.
9. The method as claimed in claim 8 , wherein the detectable marker comprises rare earth cryptates or chelates in combination with a fluorescent or chemiluminescent dye.
10. The method as claimed in claim 1 , wherein said disease is sepsis.
11. The method as claimed in claim 10 , which is carried out as part of a multiparameter determination, in which at least one further parameter relevant to sepsis diagnosis is determined simultaneously.
12. The method as claimed in claim 11 , wherein the further parameter or parameters relevant for sepsis diagnosis is or are selected from the group which consists of anti-ganglioside antibodies, the proteins calcitonin, CA 125, CA 19-9, S100B, S100A proteins, LASP-1, soluble cytokeratin fragments, in particular CYFRA 21, TPS and/or soluble cytokeratin-1 fragments (sCY1F), the peptides inflammin and CHP, fragments of the prohormones pro-ANP, pro-BNP or pro-ADM, glycine-N-acyltransferase (GNAT), carbamoylphosphate synthetase 1 (CPS 1) and C-reactive protein (CRP) or fragments thereof.
13. The method as claimed in claim 1 , wherein said cardiovascular disease is selected from the group consisting of atherosclerosis, heart failure, cardiac infarction and pulmonary arterial hypertension.
14. The method as claimed in claim 13 , which is carried out as part of a multiparameter determination, in which further parameters relevant to cardiovascular disease are determined simultaneously.
15. A method for determining the level of endothelin-1 formation in a human patient suspected of a disease selected from the group consisting of cardiovascular disease and sepsis, wherein the level of endothelin-1 formation is determined by measuring the level of a C-terminal fragment of preproendothelin-1 (SEQ ID NO.: 1), the method comprising:
obtaining a whole blood, plasma or serum sample from the patient;
contacting said sample with first antibodies that specifically bind to a first peptide within amino acids 168-212 of preproendothelin-1 (SEQ ID NO.: 1) and second antibodies that specifically bind to a second peptide within amino acids 168-212 of preproendothelin-1, one of said first and second antibodies being labeled with a detectable marker; and
measuring the level of the C-terminal fragment of preproendothelin-1 detected by said first and second antibodies, wherein the level of C-terminal fragment detected by said first and second antibodies correlates with the level of endothelin-1 formation in said patient.