Excretion of collagen derived peptides is increased in women with stress urinary incontinence.
OBJECTIVE
The objective of this study was to demonstrate that weakened pelvic floor support of the lower genitourinary tract in women with stress urinary incontinence (SUI) is due to increased collagenolysis. When fibrillar collagen is degraded, pyridinium (PYD) crosslinks are released and excreted in the urine. Degradation of collagen also results in peptide fragments of various lengths which are excreted in the urine. Degradation of mature fibrillar collagen and collagen which has not been crosslinked can be assessed independently by measurement of both PYD and collagen-derived peptides in the urine.


METHODS
Twenty-four hour urine collections were obtained from women with SUI (n = 23) and women without urinary incontinence (n = 39). Urinary PYD concentration was assayed by ELISA. The urinary concentration of helical peptide alpha1 (I) 620-633 fragments derived from collagen was assayed by competitive enzyme immunoassay. Values were normalized to creatinine.


RESULTS
The mean urine PYD concentration for women with SUI (110.8 +/- 19.7 nM/mM creatinine) was not significantly different than that for women without SUI (85.2 +/- 13.7 nM/mM creatinine). The mean urine concentration of helical peptide alpha1 (I) 620-633 for women with SUI (0.80 +/- 0.13 microg/mg creatinine) was significantly (P < 0.02) higher than that for women without SUI (0.49 +/- 0.06 microg/mg creatinine).


CONCLUSIONS
These data suggest that collagenolytic activity in women with SUI is elevated compared to continent controls, as measured by urinary helical peptide alpha1 (I) 620-633 excretion. The lack of difference in urinary PYD excretion between the two populations suggests that the increased collagenolytic activity in women with SUI, compared to continent controls, is restricted to uncrosslinked collagen.
Kushner
Leslie
L
Department of Urology, The Research Institute, North Shore-Long Island Jewish Health System, LI Jewish Medical Center, 270-05 76th Avenue, New Hyde Park, NY 11040, USA. lkushner@lij.edu
Mathrubutham
Mahesh
M
Burney
Tracey
T
Greenwald
Robert
R
Badlani
Gopal
G
D000368:Aged; D000375:Aging / Q000502:physiology; D003094:Collagen / Q000652:urine*; D003432:Cross-Linking Reagents; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D006801:Humans; D008875:Middle Aged; D010446:Peptide Fragments / Q000652:urine; D010455:Peptides / Q000652:urine*; D011726:Pyridinium Compounds / Q000737:chemistry; D014550:Urinary Incontinence, Stress / Q000652:urine*
D003432:Cross-Linking Reagents; D010446:Peptide Fragments; D010455:Peptides; D011726:Pyridinium Compounds; D003094:Collagen