Do bacterial combinations result in enhanced cytokine production? No!

Probiotic bacteria, defined as living microorganisms that have beneficial effects on human health, have been used for the prevention and treatment of a diverse range of disorders.

However, the ways in which probiotic bacteria elicit their health effects are not fully understood. One of the action mechanisms could be the ability to induce cytokines that further regulate innate and adaptive immune responses. At present there is only a limited amount of comparative data available on the ability of different probiotic strains to induce cytokine responses within the same experimental system. In addition, the effect of probiotic bacterial combinations on cytokine production in vitro is not well documented although bacterial combinations have been used in many clinical trials.

A recent study revealed that probiotic bacteria seem to direct immune responses to either a Th1 type or in anti-inflammatory way in a bacterial genera-specific manner in human leukocyte cell culture. Not all bacterial combinations resulted in enhanced cytokine production suggesting that different bacteria -- whether gram-positive or gram-negative -- compete with each other during host cell interactions. Results of this study can be exploited for designing new probiotic products that have specific health effects.

This study, performed by the groups of Dr Korpela and Professor Julkunen and to be published in February 28, 2008 in issue 8 of the World Journal of Gastroenterology. The work was carried out in collaboration with National Public Health Institute (Finland), Valio Research Centre (Finland) and University of Helsinki (Finland).

This is one of the few studies that have compared the cytokine patterns of probiotic bacteria and their combinations within the same experimental setting. It was found that probiotic bacteria induce differential cytokine responses dependent on the bacterial genera. In addition it was found that novel probiotic S. thermophilus and Leuconostoc strains are more potent inducers of Th1 type cytokines IL-12 and IFN-ƒ× than the probiotic Lactobacillus strains presently in use in probiotic products. The use of bacterial combinations did not result in enhanced cytokine production.

More detailed information on the cytokine patterns elicited by probiotic bacteria may help in designing probiotics for specific preventative or therapeutic purposes.