Interaction between bacteria and the lumenal bladder surface: modulation by pentosan polysulfate, an experimental and theoretical approach with clinical implication.

An attempt was made to interpret bacterial adsorption to the lumenal surface of the urinary bladder wall under normal and pathological conditions according to the DLVO theory of lyophobic colloid stability, which describes the interaction between a bacterium and the bladder-wall surfaces as a balance of attraction and repulsion forces. Computer modeling suggested that a decrease in the surface potential of the bladder wall may well explain an increased bacterial adsorption, possibly associated with bacterial cystitis. With the intent of preventing bacterial adsorption, treatment of bacterial cystitis by intravesical instillation of pentosan polysulfate (PPS) was evaluated. PPS is a polysaccharide with high affinity (4 +/- 2 mg/bladder) to the bladder. The attachment of PPS strongly depends on the intrinsic properties of the bacterial surface. Theoretical considerations indicate that either complete coverage of the bacterium with PPS or an absence of PPS affinity is a prerequisite for obtaining steric interaction or prevention of bacterial sorption. Experimentally, an absence of PPS affinity (0-0.7 microgram/mg bacteria) was found for bacteria commonly found during cystitis. Immunological treatment of superficial bladder cancer by bacillus Calmette-Guérin (BCG) depends on the interaction of BCG with the bladder wall. Improvement of the treatment may be obtained by increasing BCG adsorption. In this respect, the phenomenon of bridging in which PPS binds simultaneously to both BCG and the bladder-wall surface was investigated. Theoretical considerations and experimental results appeared to be in good agreement. It was found that BCG binds a considerable amount of PPS (3.4 +/- 0.3 microgram/mg BCG). In a guinea pig model the theoretical considerations, indicating the occurrence of bridging at a low and narrow range of PPS concentrations, seemed to be confirmed. In contrast to a high PPS concentration of 10 mg/ml, at a low (0.1 mg/ml) PPS concentration a significant stimulation of the BCG-associated immune reaction(s) was observed. The results suggest that to obtain PPS-induced bridging between BCG and the bladder wall and to prevent steric interaction, PPS should be instilled prior to BCG, separated by extensive washout of free PPS.