Immunohistochemical study of parathyroid hormone-related protein in vesical transitional epithelium of patients with spinal cord injury

Introduction: Parathyroid hormone-related protein (PTHrP), in addition to t he well-established role in endochrondral bone development, is believed to be an importnat mediator of cellular growth and differentiation in a number of non-bony tissues. Objectives: To compare the immunohistochemical staining of vesical transiti onal epithelium to antibodies raised to synthetic peptides of PTHrP compose d of amino acid sequences 43-52 and 127-138 inpatients with spinal cord inj ury (SCI) and neuropathic bladder (n=14), and control patients with intact neuraxis and no history of bladder cancer (n=10). Setting: Male SCI patients registered with Regional Spinal Injuries Centre, Southport, England, Intervention: Endoscopic cold cup biopsy from the trigone of the urinary bl adder was taken from patients with SCT while they were undergoing a therape utic procedure in the urinary bladder. The control samples of bladder biops ies were taken from the archives of the Department of Histopathology, Distr ict General Hospital, Southport. Immunohistochemistry was performed using r abbit antibodies raised against synthetic peptides of human PTHrP (43-52) a nd PTHrP (127-138). The biopsies were examined for immunostaining of transi tional epithelium, Results: OF the 14 biopsies of SCI patients, positive immunostaining using antibodies to both the PTHrP peptides was found in four cases; five biopsie s showed positive immunostaining only to anti-PTHrP (43-52); and five biops ies showed no immunostaining with either of the PTHrP peptides. In contrast , transitional epithelium in the biopsy specimens often control subjects wi th no history of bladder cancer showed no immunostaining with either of the PTHrP peptides. Conclusion: This study revealed that the transitional epithelium of neuropa thic urinary bladder exhibits increased predilection for positive immunohis tochemical staining for PTHrP (43-52), and to a lesser extent, to PTHrP (12 7-138), as compared to the vesical transitional epithelium of able bodied i ndividuals with no history of vesical malignancy. The possible role of PTHr P in the cellular differentiation of urothelium of neuropathic bladder, and thereby, in the pathogenesis of cystitis in SCI patients, needs to be expl ored.