Anti-inflammatory effect of an Escherichia coli extract in a mouse model of lipopolysaccharide-induced cystitis

Abstract

The bacterial extract, Uro-Vaxom^®, which consists of immunostimulating components derived from 18 Escherichia coli strains, was used for the prophylaxis of recurrent cystitis. To evaluate the anti-inflammatory effect of E. coli extract, we measured the cytokine levels of bladder tissue after oral administration and analyzed bladder inflammation by histopathologic examination in a model of lipopolysaccharide (LPS)-induced cystitis in mice. After oral administering the E. coli extract for 10 days, the cytokine [interleukin-6 (IL-6), IL-10, monocyte chemoattractant protein-1, interferon-γ (IFN-γ), tumor necrosis factor-α, IL-12p70] levels present in the bladder of female Balb/C mice were determined using a cytometric bead array. The bladder macrophage inflammatory protein-2 level was also measured using a sandwich enzyme immunoassay. After immunization with the E. coli extract, E. coli LPS was instilled into the bladders intravesically. Twenty-four hours later, the mice were sacrificed and the level of bladder inflammation was quantified using the bladder inflammatory index (BII). Significant changes in the bladder IL-6 and IFN-γ levels were observed after the E. coli extract treatment. Secretions of the other cytokines were not stimulated by the E. coli extract. The bladder instilled with LPS had high inflammation scores for edema, leukocyte infiltration, and hemorrhage in the saline treated control mice. In contrast, the E. coli extract treated mice exhibited mild inflammation of their bladders with a significant reduction in the BII scores compared with the controls. These findings might explain the anti-inflammatory effect of the E. coli extract demonstrated in clinical studies.