Determination of mouse bladder inflammatory response to E-coli lipopolysaccharide

Evaluation of the severity of histologic changes associated with cystitis i s often subjective and inconsistent from one sample to the next. The object ive of this study was to establish a consistent, reproducible method to qua ntify histologic changes in a mouse model of lipopolysaccharide (LPS)-induc ed cystitis. Either LPS (n = 8) or pyrogen-free saline (n = 8) was instille d intravesically into the bladders of female C57bk-6 J mice. Twenty-four ho urs later, mice in these groups as well as eight untreated controls were sa crificed and bladders were removed, fixed in formalin, and stained with hem atoxylin and eosin (H&E). A bladder inflammatory index (BII) was described by reviewing tissues for edema, leukocyte infiltration, and hemorrhage. Cro ss-sections were evaluated by a single pathologist in a blinded manner base d on the objective BII described. The BII method for objectively analyzing bladder inflammation was effective and reproducible. Bladders instilled wit h LPS had significantly increased inflammation scores for edema, leukocyte infiltration, and hemorrhage compared with those instilled with saline or u ntreated controls (n = 8, P < 0.05). These results demonstrate that LPS cau ses bladder inflammation when instilled intravesically and that inflammatio n of mouse bladders can be objectively quantified using the histological me thod described.