Nuclear factor kappa B mediates lipopolysaccharide-induced inflammation inthe urinary bladder

Purpose: The proteins which constitute the final common pathway linking rec eptors on cell surfaces to the inflammatory cascade have recently,been iden tified and cloned. Central to activation of this inflammatory cascade is tr anslocation from cytosol to nucleus of the nuclear transcription factor kno wn as nuclear factor-kappa B (NF-kappa B). The purpose of this study was to determine whether NF-kappa B cascade plays a role in lipopolysaccharide (L PS)-induced inflammation of the mouse urinary bladder. Materials and Methods: Bladder inflammation was induced in anesthetized mic e by intravesical instillation of lipopolysaccharide (LPS) and quantified b y morphometric analysis. The NK-1 receptors for substance P were quantified by flow cytometry. LPS-induced degradation of inhibitory I kappa B subunit was quantified by Western blotting analysis and translocation of NF-kappa B protein from cytosol to the nucleus was determined by confocal microscopy and Western blotting analysis. In addition, we determine the effect of lac tacystin, a proteosome inhibitor, on LPS-induced I kappa B degradation and NF-kappa B translocation, NK-1 receptor fluorescence intensity, and bladder inflammation. Results: LPS instillation into the mouse bladder resulted in time dependent loss of the inhibitory I kappa B subunit of the NF-kappa B protein complex . I kappa B cleavage was followed by translocation of NF-kappa B from the c ytosol to the nucleus. This was associated with increased expression of an NF-kappa B dependent inflammatory component, the NK-1 receptor. Pretreatmen t of mouse bladders with the NF-kappa B inhibitor, lactacystin, prevented c leavage of I kappa B in a dose-dependent manner. Lactacystin prevented incr eases in the NF-kappa B dependent inflammatory cascade components such as t he NK-1 receptor. At the whole tissue level, the marked inflammatory infilt rate and mucosal breakdown associated with LPS administration was completel y abolished by lactacystin. Conclusion: NF-kappa B mediates many features of urinary bladder inflammati on induced by LPS. The NF-kappa B cascade is an important target for anti-i nflammatory management of cystitis,