TIBTEC-1239; No. of Pages 2
Forum
Probiotics in transition: novel strategies Luis Gosa´lbez and Daniel Ramo´n Biopolis S.L., Parc Cientific Universitat de Vale`ncia, Calle Catedra´tico Agustı´n Escardino Benlloch 9, 46980 Paterna, Valencia, SPAIN
Regulations regarding health claims made for probiotics demand their proven effectiveness and limit the array of microbial species regarded as safe for live consumption. Novel strategies such as moving to postbiotics and genetically modified probiotics may be necessary to increase the effectiveness of microbial products.
The gut microbiome as a target for therapeutics Very recently, two studies investigating the human intestinal microbiota have made great impact in the media. One study suggests that links may exist between the consumption of non-caloric artificial sweeteners (NAS) and the development of glucose intolerance, likely due to alterations in the intestinal ecosystem [1]. Given the widespread use of NAS, this news made the headlines [2]. Findings from another study, on diurnal oscillations in the composition of the gut microbiota, suggested that jetlag may also lead to glucose intolerance and obesity [3]. This also made its way straight to the press [4], bringing the topic of gut microbiota, health, and disease once again to the forefront. In recent years, dozens of studies have implicated specific intestinal microbial profiles as potentially contributing to conditions ranging from irritable bowel syndrome to autism. These discoveries point in the same direction: the intestinal microbiota is indeed an important organ, overlooked for decades, whose role we are only beginning to understand. It is therefore only a matter of time before we witness remarkable developments in microbiota-modifying strategies such as the use of probiotics. Probiotics are in transition Traditional, generic bifidobacteria and lactic acid bacteria are already being replaced by novel, selected strains whose functional effects on humans are backed by rigorous scientific characterization. These ‘condition-specific probiotics’ are designed to address particular health conditions such as bowel inflammation or hypercholesterolemia, and have proven efficacy in human intervention trials [5,6]. However, regulatory authorities refuse to acknowledge their health claims, mainly due to the fact that foods are not considered to be treatments or cures, a role reserved exclusively for drugs. According to current regulations, foods may aim, at most, to ‘reduce the risk of developing a disease’ [7]. Thus, authorities defend the stance that human intervention trials should be conducted in a healthy, rather than diseased, population, but this approach poses challenges. It is Corresponding author: Gosa´lbez, L. ([email protected]). Keywords: probiotics; postbiotics; bioactives; GMO. 0167-7799/ ß 2015 Published by Elsevier Ltd. http://dx.doi.org/10.1016/j.tibtech.2015.01.006
often unclear whether biomarkers of healthy people should be used as indicators for intervention to allegedly prevent a disease; intervention in an otherwise healthy individual may not be beneficial. There is, however, some agreement as to so-called pre-disease states, in which levels of specific physiologic parameters found in otherwise healthy individuals predispose them to particular ailments. More importantly, it is remarkably more difficult to induce changes in the physiology of a healthy individual than of a diseased individual, therefore requiring the active ingredients to be relatively potent. However, are probiotics as we conceive them today (orally administered, natural, live bacteria) powerful enough? Current regulations also restrict the microbial species that may be used as foods to those listed as ‘Qualified Presumption of Safety’ (QPS) or ‘Generally Recognized As Safe’ (GRAS) which, combined, include 75 species [8,9], of which 25 are currently used as probiotics. Taking into account that each human intestine is inhabited by between 500 and 1000 different microbial species, the current array of probiotics seems to be somewhat restricted. The probiotics industry thus faces two limitations. Natural, live bacteria may not be powerful enough to induce the changes in healthy individuals necessary to obtain claims recognition. In addition, only a handful of microbial species may be employed as ingredients or supplements in a viable state. Probiotics, prebiotics, and postbiotics The molecular mechanisms underlying the action of ingested microorganisms remain unclear. In most cases the effect is mediated through an interaction between molecules on the surface of the microorganism and the host immune system, triggering, for instance, an antiinflammatory response. Surprisingly, bacterial metabolism often seems to be irrelevant, although in other cases efficacy is presumed to be based on the production of bacterial metabolites such as short-chain fatty acids. Recent research indicates the relationship may be more complex and reside in microbial ecological networks inside the host intestine; it has also been postulated that some probiotics are actually prebiotics on which other microbial strains feed. Therefore we may soon witness a revolution in this field. Once we pinpoint the ultimate molecular mechanism of each functional strain we will have paved the way to implementing different strategies. In this scenario, ‘postbiotics’ or ‘bioactives’, non-viable bacterial products or metabolites with a biological effect on the host, may be an effective way to increase the potency of active microorganisms and make them qualify as functional ingredients or even drugs. To draw an analogy, purified and concentrated vitamins, rather than the fruits that produce Trends in Biotechnology xx (2015) 1–2
1
TIBTEC-1239; No. of Pages 2
Forum them, are considered a functional ingredient, and the same applies to antibiotics from filamentous fungi in the realm of pharmaceuticals. Most modern drugs and functional food ingredients were originally isolated from plants or microorganisms. Why should this not also be the case for postbiotics from gut bacteria? A compromise between using whole live cells and concentrated bioactives may be to use whole microorganisms, but in a non-viable state. There is very strong evidence indicating that some inactivated probiotics retain their functionality. This strategy has enormous potential in reducing the previously discussed legal hurdles given the apparent aversion of regulators to whole, living organisms. Furthermore, it could reduce some technical issues because many efforts are currently focused on ensuring that the ingested microorganisms survive in the intestine. An interesting example of an inactivated probiotic is the recently released product Nyaditum resae1, an immunomodulatory food supplement consisting of heat-inactivated Mycobacterium manresensis, which may reduce the risk of developing active tuberculosis [10]. This is an approved food supplement composed of dead cells of a non-QPS/ GRAS organism for the management and risk-reduction of disease through the modulation of the host immune system. This example also highlights that probiotics are increasingly being commercialized as supplements, in capsules, rather than as ingredients in foods such as dairy products, making their appearance and consumption patterns more similar to those of drugs than of foods. This, together with the health-claims aspirations of functional foods, is bringing food and pharmaceuticals closer together. Concluding remarks and future perspectives Looking further ahead, the future of live microorganisms may lie in the use of genetically modified organisms (GMOs). This strategy, likely to become a reality only in the pharmaceutical sphere at first, may be used to employ microorganisms as long-term, renewable drug delivery systems. This promising approach has already caught the eye of some pharmaceutical companies, and some products have started the long journey of clinical trials [11,12]. This approach has, nevertheless, multiple regulatory hurdles to overcome over and above the purely technological challenges. Legislators regard these treatments as gene therapy, and strict biocontainment measures are required to ensure that the organism does not survive after leaving the body, in compliance with regulations governing the environmental release of GMOs. Perhaps
2
Trends in Biotechnology xxx xxxx, Vol. xxx, No. x
we have reached an important, but familiar, crossroads. In the same way as the yet-to-be-approved ‘golden rice’ was genetically modified to express b-carotene to address a health problem, why not engineer some of our bacterial symbionts to produce nutrients such as essential amino acids or vitamins inside us? We find ourselves at an exciting moment in time, having reached the point where we are rethinking the role of the human microbiome. Functional foods and drugs are certain to be revolutionized by the development of microbiome science. However, approaches more sophisticated than the use of natural, live organisms may be necessary. Employing concentrated microbial bioactive molecules and the genetic modification of microorganisms may become the most successful strategies to boost the potential of microbes as functional ingredients and therapeutic agents. References 1 Suez, J. et al. (2014) Artificial sweeteners induce glucose intolerance by altering the gut microbiota. Nature 514, 181–186 2 Sample, I. (2014) Artificial sweeteners may promote diabetes. Guardian 17 September 3 Thaiss, C.A. et al. (2014) Transkingdom control of microbiota diurnal oscillations promotes metabolic homeostasis. Cell 159, 514–529 4 Feltman, R. (2014) Even the bacteria in your gut get jet lag. Washington Post 17 October 5 Olivares, M. et al. (2014) Double-blind, randomised, placebo-controlled intervention trial to evaluate the effects of Bifidobacterium longum CECT 7347 in children with newly diagnosed coeliac disease. Br. J. Nutr. 112, 30–40 6 Jones, M.L. et al. (2012) Cholesterol lowering and inhibition of sterol absorption by Lactobacillus reuteri NCIMB 30242: a randomized controlled trial. Eur. J. Clin. Nutr. 66, 1234–1241 7 European Commission (2006) Regulation EC No 1924/2006 of the European Parliaments and the Council of 20 December 2006 on nutrition and health claims made on foods. Official J. Eur. Union L404, 9–25 8 EFSA Panel on Biological Hazards (BIOHAZ) (2013) Scientific opinion on the maintenance of the list of QPS biological agents intentionally added to food and feed. EFSA J. 11, 3449 9 US Food and Drug Administration (2014) GRAS Notices. Published online October 31, 2014. http://www.accessdata.fda.gov/scripts/fdcc/ ?set=GRASNotices 10 Montane´, E. et al. (2014) Clinical trial with the food supplement Nyaditum resae: a new tool to reduce the risk of developing active tuberculosis (45th World Conference on Lung Health, Barcelona). Int. J. Tuberc. Lung Cancer 18 (Suppl. 1), S427 11 ClinicalTrials gov (2008) A Phase 2a Study to Evaluate the Safety, Tolerability, Pharmacodynamics and Efficacy of AG011 in Ulcerative Colitis (NCT00729872), US National Institutes of Health (https:// clinicaltrials.gov/ct2/show/NCT00729872) 12 ClinicalTrials gov (2014) Study to Assess Safety and Tolerability of AG013 in Oral Mucositis in Subjects Receiving Induction Chemotherapy for the Treatment of Cancers of the Head and Neck (NCT00938080), US National Institutes of Health (https:// clinicaltrials.gov/ct2/show/NCT00938080)
Forum
Probiotics in transition: novel strategies Luis Gosa´lbez and Daniel Ramo´n Biopolis S.L., Parc Cientific Universitat de Vale`ncia, Calle Catedra´tico Agustı´n Escardino Benlloch 9, 46980 Paterna, Valencia, SPAIN
Regulations regarding health claims made for probiotics demand their proven effectiveness and limit the array of microbial species regarded as safe for live consumption. Novel strategies such as moving to postbiotics and genetically modified probiotics may be necessary to increase the effectiveness of microbial products.
The gut microbiome as a target for therapeutics Very recently, two studies investigating the human intestinal microbiota have made great impact in the media. One study suggests that links may exist between the consumption of non-caloric artificial sweeteners (NAS) and the development of glucose intolerance, likely due to alterations in the intestinal ecosystem [1]. Given the widespread use of NAS, this news made the headlines [2]. Findings from another study, on diurnal oscillations in the composition of the gut microbiota, suggested that jetlag may also lead to glucose intolerance and obesity [3]. This also made its way straight to the press [4], bringing the topic of gut microbiota, health, and disease once again to the forefront. In recent years, dozens of studies have implicated specific intestinal microbial profiles as potentially contributing to conditions ranging from irritable bowel syndrome to autism. These discoveries point in the same direction: the intestinal microbiota is indeed an important organ, overlooked for decades, whose role we are only beginning to understand. It is therefore only a matter of time before we witness remarkable developments in microbiota-modifying strategies such as the use of probiotics. Probiotics are in transition Traditional, generic bifidobacteria and lactic acid bacteria are already being replaced by novel, selected strains whose functional effects on humans are backed by rigorous scientific characterization. These ‘condition-specific probiotics’ are designed to address particular health conditions such as bowel inflammation or hypercholesterolemia, and have proven efficacy in human intervention trials [5,6]. However, regulatory authorities refuse to acknowledge their health claims, mainly due to the fact that foods are not considered to be treatments or cures, a role reserved exclusively for drugs. According to current regulations, foods may aim, at most, to ‘reduce the risk of developing a disease’ [7]. Thus, authorities defend the stance that human intervention trials should be conducted in a healthy, rather than diseased, population, but this approach poses challenges. It is Corresponding author: Gosa´lbez, L. ([email protected]). Keywords: probiotics; postbiotics; bioactives; GMO. 0167-7799/ ß 2015 Published by Elsevier Ltd. http://dx.doi.org/10.1016/j.tibtech.2015.01.006
often unclear whether biomarkers of healthy people should be used as indicators for intervention to allegedly prevent a disease; intervention in an otherwise healthy individual may not be beneficial. There is, however, some agreement as to so-called pre-disease states, in which levels of specific physiologic parameters found in otherwise healthy individuals predispose them to particular ailments. More importantly, it is remarkably more difficult to induce changes in the physiology of a healthy individual than of a diseased individual, therefore requiring the active ingredients to be relatively potent. However, are probiotics as we conceive them today (orally administered, natural, live bacteria) powerful enough? Current regulations also restrict the microbial species that may be used as foods to those listed as ‘Qualified Presumption of Safety’ (QPS) or ‘Generally Recognized As Safe’ (GRAS) which, combined, include 75 species [8,9], of which 25 are currently used as probiotics. Taking into account that each human intestine is inhabited by between 500 and 1000 different microbial species, the current array of probiotics seems to be somewhat restricted. The probiotics industry thus faces two limitations. Natural, live bacteria may not be powerful enough to induce the changes in healthy individuals necessary to obtain claims recognition. In addition, only a handful of microbial species may be employed as ingredients or supplements in a viable state. Probiotics, prebiotics, and postbiotics The molecular mechanisms underlying the action of ingested microorganisms remain unclear. In most cases the effect is mediated through an interaction between molecules on the surface of the microorganism and the host immune system, triggering, for instance, an antiinflammatory response. Surprisingly, bacterial metabolism often seems to be irrelevant, although in other cases efficacy is presumed to be based on the production of bacterial metabolites such as short-chain fatty acids. Recent research indicates the relationship may be more complex and reside in microbial ecological networks inside the host intestine; it has also been postulated that some probiotics are actually prebiotics on which other microbial strains feed. Therefore we may soon witness a revolution in this field. Once we pinpoint the ultimate molecular mechanism of each functional strain we will have paved the way to implementing different strategies. In this scenario, ‘postbiotics’ or ‘bioactives’, non-viable bacterial products or metabolites with a biological effect on the host, may be an effective way to increase the potency of active microorganisms and make them qualify as functional ingredients or even drugs. To draw an analogy, purified and concentrated vitamins, rather than the fruits that produce Trends in Biotechnology xx (2015) 1–2
1
TIBTEC-1239; No. of Pages 2
Forum them, are considered a functional ingredient, and the same applies to antibiotics from filamentous fungi in the realm of pharmaceuticals. Most modern drugs and functional food ingredients were originally isolated from plants or microorganisms. Why should this not also be the case for postbiotics from gut bacteria? A compromise between using whole live cells and concentrated bioactives may be to use whole microorganisms, but in a non-viable state. There is very strong evidence indicating that some inactivated probiotics retain their functionality. This strategy has enormous potential in reducing the previously discussed legal hurdles given the apparent aversion of regulators to whole, living organisms. Furthermore, it could reduce some technical issues because many efforts are currently focused on ensuring that the ingested microorganisms survive in the intestine. An interesting example of an inactivated probiotic is the recently released product Nyaditum resae1, an immunomodulatory food supplement consisting of heat-inactivated Mycobacterium manresensis, which may reduce the risk of developing active tuberculosis [10]. This is an approved food supplement composed of dead cells of a non-QPS/ GRAS organism for the management and risk-reduction of disease through the modulation of the host immune system. This example also highlights that probiotics are increasingly being commercialized as supplements, in capsules, rather than as ingredients in foods such as dairy products, making their appearance and consumption patterns more similar to those of drugs than of foods. This, together with the health-claims aspirations of functional foods, is bringing food and pharmaceuticals closer together. Concluding remarks and future perspectives Looking further ahead, the future of live microorganisms may lie in the use of genetically modified organisms (GMOs). This strategy, likely to become a reality only in the pharmaceutical sphere at first, may be used to employ microorganisms as long-term, renewable drug delivery systems. This promising approach has already caught the eye of some pharmaceutical companies, and some products have started the long journey of clinical trials [11,12]. This approach has, nevertheless, multiple regulatory hurdles to overcome over and above the purely technological challenges. Legislators regard these treatments as gene therapy, and strict biocontainment measures are required to ensure that the organism does not survive after leaving the body, in compliance with regulations governing the environmental release of GMOs. Perhaps
2
Trends in Biotechnology xxx xxxx, Vol. xxx, No. x
we have reached an important, but familiar, crossroads. In the same way as the yet-to-be-approved ‘golden rice’ was genetically modified to express b-carotene to address a health problem, why not engineer some of our bacterial symbionts to produce nutrients such as essential amino acids or vitamins inside us? We find ourselves at an exciting moment in time, having reached the point where we are rethinking the role of the human microbiome. Functional foods and drugs are certain to be revolutionized by the development of microbiome science. However, approaches more sophisticated than the use of natural, live organisms may be necessary. Employing concentrated microbial bioactive molecules and the genetic modification of microorganisms may become the most successful strategies to boost the potential of microbes as functional ingredients and therapeutic agents. References 1 Suez, J. et al. (2014) Artificial sweeteners induce glucose intolerance by altering the gut microbiota. Nature 514, 181–186 2 Sample, I. (2014) Artificial sweeteners may promote diabetes. Guardian 17 September 3 Thaiss, C.A. et al. (2014) Transkingdom control of microbiota diurnal oscillations promotes metabolic homeostasis. Cell 159, 514–529 4 Feltman, R. (2014) Even the bacteria in your gut get jet lag. Washington Post 17 October 5 Olivares, M. et al. (2014) Double-blind, randomised, placebo-controlled intervention trial to evaluate the effects of Bifidobacterium longum CECT 7347 in children with newly diagnosed coeliac disease. Br. J. Nutr. 112, 30–40 6 Jones, M.L. et al. (2012) Cholesterol lowering and inhibition of sterol absorption by Lactobacillus reuteri NCIMB 30242: a randomized controlled trial. Eur. J. Clin. Nutr. 66, 1234–1241 7 European Commission (2006) Regulation EC No 1924/2006 of the European Parliaments and the Council of 20 December 2006 on nutrition and health claims made on foods. Official J. Eur. Union L404, 9–25 8 EFSA Panel on Biological Hazards (BIOHAZ) (2013) Scientific opinion on the maintenance of the list of QPS biological agents intentionally added to food and feed. EFSA J. 11, 3449 9 US Food and Drug Administration (2014) GRAS Notices. Published online October 31, 2014. http://www.accessdata.fda.gov/scripts/fdcc/ ?set=GRASNotices 10 Montane´, E. et al. (2014) Clinical trial with the food supplement Nyaditum resae: a new tool to reduce the risk of developing active tuberculosis (45th World Conference on Lung Health, Barcelona). Int. J. Tuberc. Lung Cancer 18 (Suppl. 1), S427 11 ClinicalTrials gov (2008) A Phase 2a Study to Evaluate the Safety, Tolerability, Pharmacodynamics and Efficacy of AG011 in Ulcerative Colitis (NCT00729872), US National Institutes of Health (https:// clinicaltrials.gov/ct2/show/NCT00729872) 12 ClinicalTrials gov (2014) Study to Assess Safety and Tolerability of AG013 in Oral Mucositis in Subjects Receiving Induction Chemotherapy for the Treatment of Cancers of the Head and Neck (NCT00938080), US National Institutes of Health (https:// clinicaltrials.gov/ct2/show/NCT00938080)
