Purpose: Proteus mirabilis is a common cause of urinary tract infection. We determined the role of Tamm-Horsfall protein as a host defense factor against the cystitis and pyelonephritis caused by P. mirabilis.
Materials and methods: We generated Tamm-Horsfall protein gene knockout mice using homologous recombination. We introduced P. mirabilis transurethrally into the bladder of Tamm-Horsfall protein deficient (THP(-/-)) and genetically similar WT (THP(+/+)) mice. We cultured urine to quantitate the degree of bacteriuria. We examined bladders and kidneys grossly and histomorphometrically to determine the intensity of inflammation.
Results: THP(-/-) mice had more severe bacteriuria and cystitis than THP(+/+) mice. THP(-/-) mice had more pyelonephritic abscesses than THP(+/+) mice. The severity of histological pyelonephritis on semiquantitative histomorphometric analysis appeared to be greater in THP(-/-) mice. The difference between the 2 groups approached but did not attain statistical significance (p = 0.053).
Conclusion: Tamm-Horsfall protein acts as a host defense factor against P. mirabilis induced urinary tract infection.