TNF-alpha neutralization decreases nuclear factor-kappaB activation and apoptosis during renal obstruction.
BACKGROUND
Obstruction of the upper urinary tract is an important cause of progressive renal injury in children. While tumor necrosis factor-alpha (TNF-alpha) and nuclear factor kappaB (NFkappaB) have independently been implicated in the pathophysiology of this process, TNF-alpha's role in obstruction-induced NFkappaB activation has not previously been investigated.


METHODS
To study this, male Sprague Dawley rats were subjected to 3 days of unilateral ureteral obstruction (UUO) versus sham operation. Twenty-four hours prior to surgery and 2 days after, rats received either a vehicle or a pegylated form of soluble TNF receptor type 1 (PEG-sTNFR1). The kidneys were harvested 3 days postoperatively, and tissue samples were analyzed for TNF-alpha expression (ELISA), NFkappaB activation (EMSA, immunohistochemistry), IkappaB degradation (Western blot), angiotensinogen expression (Western blot), and apoptosis (TUNEL).


RESULTS
Renal cortical TNF-alpha levels, NFkappaB activation, IkappaB degradation, angiotensinogen expression, and apoptotic cell death were significantly increased in response to obstruction. In contrast, TNF-alpha neutralization significantly reduced obstruction-induced TNF-alpha production, NFkappaB activation, IkappaB degradation, angiotensinogen expression, and renal tubular cell apoptosis.


CONCLUSIONS
TNF-alpha's potent pro-inflammatory and cytotoxic effect during renal obstruction is directed through NFkappaB activation via increased IkappaB-alpha phosphorylation. As the role of TNF-alpha and NFkappaB in renal obstruction are further defined, the development of therapeutic strategies that limit or prevent obstruction-induced renal injury may be realized.
Meldrum
Kirstan K
KK
Department of Urology, Indiana University Medical Center, Indianapolis, Indiana 46202, USA. kmeldrum@iupui.edu
Metcalfe
Peter
P
Leslie
Jeffrey A
JA
Misseri
Rosalia
R
Hile
Karen L
KL
Meldrum
Daniel R
DR
D000818:Animals; D017209:Apoptosis; D002648:Child; D004797:Enzyme-Linked Immunosorbent Assay; D006801:Humans; D020672:I-kappa B Proteins / Q000378:metabolism; D007150:Immunohistochemistry; D007249:Inflammation; D007674:Kidney Diseases / Q000503:physiopathology*; D008297:Male; D016328:NF-kappa B / Q000502:physiology*; D010766:Phosphorylation; D051381:Rats; D017207:Rats, Sprague-Dawley; D014409:Tumor Necrosis Factor-alpha / Q000096:biosynthesis* / Q000502:physiology; D014524:Urethral Obstruction / Q000503:physiopathology*
D020672:I-kappa B Proteins; D016328:NF-kappa B; D014409:Tumor Necrosis Factor-alpha