Failed endopyelotomy: low expression of TGF beta regardless of the presence or absence of crossing vessels.

BACKGROUND AND OBJECTIVE

Endopyelotomy relies on Davis' intubated ureterotomy principle of healing by secondary intention and smooth-muscle regeneration. Approximately 15% of endopyelotomies fail, and the restrictured segment almost always shows evidence of reactive fibrosis with little smooth-muscle regeneration. Previous data suggests that an elevation of TGF beta in obstructed ureteropelvic junctures may be necessary for successful tissue repair following endopyelotomy. The role of crossing vessels in endopyelotomy failure is very controversial. To better understand the pathophysiology of endopyelotomy failure, the expression of transforming growth factor-beta (TBG beta) in patients with a failed endopyelotomy and crossing vessels was compared with that in patients without crossing vessels, as well as those having primary pyeloplasty or a normal ureteropelvic junction (UPJ).

MATERIALS AND METHODS

The expression of TGF beta was detected immunohistochemically in slide-mounted thin sections (4 microns) cut from paraffin-blocked adult UPJ segments obtained during primary pyeloplasty (N = 11), secondary pyeloplasty after failed endopyelotomy with documented crossing vessels (N = 10), secondary pyeloplasty after failed endopyelotomy without crossing vessels (N = 11), and normal UPJs removed during nephrectomy for purposes unrelated to obstruction (N = 11). Expression was graded on a scale of 0 to 4.

RESULTS

The combined failed endopyelotomy group had a significantly (P < 0.05) lower level of TGF beta (1.9 +/- 0.7) than did primary obstructed UPJs (2.6 +/- 0.7). The TGF beta level in the crossing vessels group (1.9 +/- 0.7) did not differ from that in the group without crossing vessels (1.8 +/- 0.7), nor did it differ from that in the group with normal UPJs (1.6 +/- 0.7). As expected, primary obstructed UPJs had a significantly higher level of TGF beta than normal ones (P < 0.02).

CONCLUSIONS

Obstructed UPJs that had failed endopyelotomy had a similarly reduced level of TGF beta whether or not crossing vessels were present. These data suggest that an elevation of TGF beta in obstructed UPJs may be necessary for successful tissue repair after endopyelotomy and that the presence of crossing vessels is probably not relevant.