Effects of lactobacillus on normal and tumour bearing mice

Abstract

Mycobacterium bovis, Bacillus Calmette Guerin (BCG) immunotherapy is the current gold standard for superficial bladder cancer treatment but has a non-responder rate of 30 - 50% and side-effects are common. Using the murine orthotopic bladder cancer model, Lactobacillus rhamnosus GG (LGG) instillations was found to confer a 30% survival advantage over PBS controls; and the cure rate of lyophilised (lyo) LGG was comparable to BCG Immucyst (78% and 69% respectively). While LGG instillations were well-tolerated, BCG Immucyst resulted in severe inflammation and instillation failure. Lyo LGG therapy could induce massive neutrophil and macrophage infiltration into the tumour within two instillations. It also induced changes in local lymph nodes and spleen Ly6G+, Mac-3+ and CD3+CD8+ cell populations and reduced the amount of pro-metastatic proteins (osteopontin and pro-MMP9) in the bladder. In vitro experiments also found LGG to induce cell death without the need for direct contact with the cancer cells.