Methods of diagnosing and treating heart failure
This invention relates to novel phosphorylation sites in cardiac Troponin I that are associated with the onset of heart failure. The phosphorylation sites, i.e., serine 5, tyrosine 26, threonine 51, serine 166, threonine 181 and/or serine 199, can be used as biomarkers for (i) identifying subjects at risk for the development of heart failure, (ii) treating subjects having a higher than normal level of the biomarker, and (iii) monitoring therapy of a subject at risk for the development of heart failure. Also described are antibodies, reagents, and kits for carrying out a method of the present invention.
1. A method of diagnosing and treating heart failure in a subject, comprising:
(a) obtaining a biological sample from the subject;
(b) measuring phosphorylation level at serine 5, tyrosine 26, serine 166, threonine 181 and/or serine 199 of a cardiac Troponin I protein or peptide in the biological sample by mass spectrometry, wherein the mass spectrometry is multiple reaction monitoring mass spectrometry;
(c) diagnosing the subject with heart failure by comparing the measured phosphorylation level in the biological sample to a control level in a normal subject population; wherein a phosphorylation level decrease at serine 5, a phosphorylation level decrease at tyrosine 26, a phosphorylation level increase at serine 166, a phosphorylation level increase at threonine 181, and/or a phosphorylation level increase at serine 199, is indicative of heart failure in the subject; and
(d) administering a treatment for heart failure to the subject.
2. A method of detecting cardiac Troponin I phosphorylation at serine 5, tyrosine 26, serine 166, threonine 181 and/or serine 199 comprising:
(a) obtaining a test sample; and
(b) analyzing the test sample by mass spectrometry to detect phosphorylated serine 5, tyrosine 26, serine 166, threonine 181 and/or serine 199 in the test sample, wherein the mass spectrometry is multiple reaction monitoring mass spectrometry.
3. The method of claim 1 , further comprising detecting a level of a second marker indicative of heart failure.
4. The method of claim 3 , wherein the second marker is cardiac specific isoforms of desmin, troponin T (TnT), CK-MB, myoglobin, or brain natriuretic peptide (BNP).
5. The method of claim 4 , wherein the second marker is brain natriuretic peptide (BNP).
6. The method of claim 1 , wherein the subject is a mammal.
7. The method of claim 1 , wherein the subject is a human, dog, or horse.
8. The method of claim 1 , wherein the subject is a human.
9. The method of claim 1 , wherein the treatment for heart failure is selected from one or more of cardiac resynchronization therapy; heart valve repair or replacement; implantable cardioverter-defibrillator; heart pump; heart transplant; percutaneous coronary intervention; coronary bypass surgery; surgical correction of congenital heart defects; and administration of an angiotensin-converting enzyme inhibitor, angiotensin II receptor blocker, digoxin, beta blockers, diuretics, or aldosterone antagonist.
10. The method of claim 1 , wherein the biological sample is blood, plasma, or serum.
11. The method of claim 1 , wherein the biological sample is cardiac tissue, tissue homogenate, or tissue slice.