Probiotaceuticals: Back to the future?

Probiotic research has undergone some exciting and unanticipated changes in direction since the 2010 commentary by GSH, which speculated on probiotics being ultimately utilized as "factories" capable of releasing pharmaceutical-grade metabolites with therapeutic potential for a wide range of primarily gastrointestinal disorders. Indeed, the unrelenting search for new alternatives to antibiotics has further stimulated the development of "next-generation" probiotics. Postbiotics, defined as inanimate microorganisms and/or their components that confer a health benefit on the host, remain at the forefront of current probiotic research, with increasing numbers of probiotic species, strains, and substrains now being identified and further exploited as pharmabiotics; probiotics with a proven pharmacologic role in health and disease that have been subjected to clinical trial prior to approval by regulatory bodies. However, perhaps the most unanticipated probiotic development over the past 15 y has been the emergence of psychobiotics with the potential to improve aspects of mental health, such as depression and anxiety, through the release of bioactive metabolites. Moreover, the recent identification of pharmacobiotics, probiotics capable of facilitating the effectiveness of conventional pharmaceutical drugs, is opening new avenues for probiotic applications to combat a range of diseases, including cancers of the digestive system. Although in its infancy, recent reports of oncobiotics with antineoplastic properties are further expanding the potential for certain next-generation probiotics to impact current cancer treatment regimens and possibly even contribute to cancer prevention. Looking to the next 15 y of probiotic development, one could perhaps predict the ultimate development of regulatory-approved xenopostbiotic formulations comprising metabolites with the capacity to improve digestive health, decrease the severity of intestinal disease, and increase the effectiveness of conventional pharmaceuticals, whilst simultaneously improving cognitive functioning and mental welfare. Although speculative, these xenopostbiotic formulations could prove especially effective for the adjunctive treatment of serious chronic diseases such as cancer.