Monday, 14 March 2011

More good bacteria

Not all bacteria are bad, as we know. There are "good bacteria" that live in our gut and help us to digest our food. Now, bacteria have been harnessed to help doctors and clinicians as a vector to treat or prevent disease. This bacterial gene therapy is known as "bactofection".

Peter Celec and his team in the Slovak Republic researched the usage of bacteria to treat inflammatory bowel disease.1 The Salmonella bacteria carried genes for an antioxidant (superoxide dismutase) and a protein that stimulates the immune response (monocyte chemoattractant protein-1). Bactofection was applied to mice suffering from inflammatory bowel disease (colitis), and alleviated colitis symptoms in these mice when compared to untreated mice.

Listeria has been tested as a vector to deliver therapeutic genes and proteins to cancer cells and immune cells.2 Listeria is a particularly good candidate as it is very efficient at entering host cells, and can move from cell to cell without having to exit it anywhere. Moreover it is safe and effective in clinical trials. Anti-cancer genes can be targeted to tumours by packaging them inside this pathogen.


Salmonella has also been used as a vehicle to treat cancer. 3 Both Listeria and Salmonella infect and can survive in antigen presenting cells (cells that form part of the immune system). They can be engineered to express tumour-like proteins which stimulates the body's immune system to break tolerance against tumour cells that look a lot like "self" to the body.



Image: Salmonella enterica serovar typhimurium



1Palffy R, Gardlik R, Behuliak M, Jani P, Balakova D, Kadasi L, Turna J, Celec P. Salmonella-mediated gene therapy in experimental colitis in mice. Exp Biol Med (Maywood). (2011) 236:177-83.

2Tangney M, Gahan CGM. Listeria monocytogenes as a Vector for Anti-Cancer Therapies. Current Gene Therapy (2010) 10: 46-55.

3Paterson Y, Guirnalda PD, Wood LM. Listeria and Salmonella bacterial vectors of tumor-associated antigens for cancer immunotherapy. Seminars in Immunology (2010) 22: 183-189.





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