Non-viable Probiotics Research Articles

Clinical and Immunologic Effects of Paraprobiotics in Long-COVID Patients: A Pilot Study.

After the enormous health burden during the acute stages of the COVID-19 pandemic, we are now facing another important challenge, that is, long-COVID, a clinical condition with often disabling signs and symptoms of the neuropsychiatric, gastrointestinal, respiratory, cardiovascular, and immune systems. While the pathogenesis of this syndrome is still poorly understood, alterations of immune function and the gut microbiota seem to play important roles. Because affected individuals are frequently unable to work for prolonged periods and suffer numerous health compromises, effective treatments represent a major unmet medical need. Multiple potential therapies have been tried, but none is approved yet. Approaches that are able to influence the immune system and gut microbiota such as probiotics and paraprobiotics, i.e., nonviable probiotics, seem promising candidates. We, therefore, evaluated the clinical and immunologic effects of paraprobiotics in a small pilot study. A total of 6 patients with long-COVID were followed systematically for more than 12 months after disease onset using standardized validated questionnaires, a smartphone app, and wearable sensors to assess neurocognitive function, fatigue, depressiveness, autonomic nervous system alterations, and quality of life. We then offered patients defined paraprobiotics for 4 weeks and evaluated them at the end of the treatment period using the same questionnaires, smartphone app, and wearable sensors. In addition, a comprehensive immunophenotyping and gut microbiota analysis was performed before and after treatment. Improvements in several of the neurologic symptoms such as dysautonomia, fatigue, and depression were documented using both patient-reported outcomes and data from the smartphone app and wearable sensors. Of interest, the expression of activation markers on some immune cell populations such as B cells and nonclassical monocytes and the expression of toll-like receptor 2 (TLR2) on T cells were reduced after paraprobiotics treatment. Our results suggest that paraprobiotics might exert positive effects in patients with long-COVID most likely by modulating immune cell activation and expression of TLR2 on T cells. Further studies with paraprobiotics should confirm the promising observations of this small pilot study and hopefully not only improve the outcome of long-COVID but also unravel the pathomechanisms of this condition. This study provides Class IV evidence that paraprobiotics increase the probability of favorable changes of clinical and immunologic markers in patients with long-COVID.

Co-administration of the prebiotic 1-kestose and the paraprobiotic Lactiplantibacillus plantarum FM8 in magellanic penguins promotes the activity of intestinal Lactobacillaceae and reduces the plc gene levels encoding Clostridium perfringens toxin.

Despite the well-known potential health benefits of prebiotics and non-viable probiotics (paraprobiotics) in various animal species, research regarding their use in penguins is scarce. Our study aimed to investigate the impact of a combined administration of prebiotics and paraprobiotics (referred to here as "parasynbiotics") on the gut microbiome and overall health of Magellanic penguins (Spheniscus magellanicus). The parasynbiotics consisted of 1-kestose, which is a fructooligosaccharide comprising sucrose and fructose, and heat-killed Lactiplantibacillus plantarum FM8, isolated from pickled vegetables. It was administered to eight penguins aged <3 years (Young-group) and nine penguins aged >17 years (Adult-group) for 8 weeks. Results from 16S rRNA sequencing revealed that compared to baseline, parasynbiotic administration significantly decreased the relative abundance of intestinal Clostridiaceae_222000 in both groups and significantly increased that of Lactobacillaceae in the Young-group. Quantitative real-time polymerase chain reaction revealed a significant decrease in the plc gene levels encoding alpha-toxin of Clostridium perfringens in the Young-group after parasynbiotic administration (P=0.0078). In the Young-group, parasynbiotic administration significantly increased the plasma levels of total alpha-globulin (P=0.0234), which is associated with inflammatory responses. Furthermore, exposure of dendritic cells to heat-killed L. plantarum FM8 promoted the secretion of interleukin 10, a major anti-inflammatory cytokine. Overall, parasynbiotic administration enhanced the activity of gut Lactobacillaceae, decreased the levels of C. perfringens and its toxin encoding plc gene, and reduced inflammatory response in penguins. These results provide novel insights into the potential benefits of parasynbiotics for improving penguin health.

Nanoparticle-enhanced postbiotics: Revolutionizing cancer therapy through effective delivery

AimGastric cancer contributes to cancer-related fatalities. Conventional chemotherapy faces challenges due to severe adverse effects, prompting recent research to focus on postbiotics, which are safer biomolecules derived from nonviable probiotics. Despite promising in vitro results, efficient in vivo delivery systems remain a challenge. This study aimed to design a potential nanoparticle (NP) formulation encapsulating the Lacticaseibacillus paracasei GMNL-133 (SGMNL-133) isolate to enhance its therapeutic efficacy in treating gastric cancer. Main methodsWe successfully isolated GMNL-133 (SGMNL-133) by optimizing the lysate extraction and column elution processes for L. paracasei GMNL-133, resulting in substantial enhancement of its capacity to inhibit the proliferation of gastric cancer cells. Additionally, we developed a potential NP utilizing arginine-chitosan and fucoidan encapsulating SGMNL-133. Key findingsThis innovative approach protected the SGMNL-133 from degradation by gastric acid, facilitated its penetration through the mucus layer, and enabled interaction with gastric cancer cells. Furthermore, in vivo experiments demonstrated that the encapsulation of SGMNL-133 in NPs significantly enhanced its efficacy in the treatment of orthotopic gastric tumors while simultaneously reducing tissue inflammation levels. SignificanceRecent research highlights postbiotics as a safe alternative, but in vivo delivery remains a challenge. Our study optimized the extraction of the lysate and column elution of GMNL-133, yielding SGMNL-133. We also developed NPs to protect SGMNL-133 from gastric acid, enhance mucus penetration, and improve the interaction with gastric cancer cells. This combination significantly enhanced drug delivery and anti-gastric tumor activity.

Postbiotics of Bacillus subtilis LCBS1 have beneficial effects on bullfrogs (Lithobates catesbeianus)

Our previous studies found live Bacillus subtilis LCBS1 could improve the utilization efficiency and intestinal health in bullfrog (Lithobates catesbeianus) fed the SM-based diet. However, non-viable probiotics may play the health benefits of probiotics. Therefore, 0.8% NaCl (negative control group, CG), LCBS1 live bacteria (positive control group, LB) and postbiotics from LCBS1 (heat-inactivated bacteria, HIB; cell-free extract, CE; cell-free supernatant, CS) were added to the SM-based diets and their effects on growth performance, immunity and intestinal health were evaluated in a 56 days feeding trial in bullfrog. Dietary supplement LB, HIB and CE significantly improved weight gain and feed efficiency. Meanwhile, apparent digestibility coefficients of protein were significantly increased, and the pH values of jejunum were significantly decreased in the HIB and CE groups compared with the CG, and indifferent with the LB group. Lower jejunum malondialdehyde concentration, and higher jejunum total antioxidant capacity and whole-body protein deposition in the HIB group were observed compared with the CG, and indifferent with the LB group. Dietary supplement LB and HIB significantly increased activities of lipase and protease in the jejunum, and serum complement 4 level and alkaline phosphatase activity. Higher jejunum il-4 expression in the LB and HIB groups, and lower jejunum tnf-α expression in the HIB, CE and CS groups were observed. Furthermore, the jejunal physical barrier was improved in the LB, HIB, and CE groups. Higher villus height, muscular thickness and zo-1 expression, lower serum diamine oxidase activity and D-lactate concentration in the LB, HIB and CE groups were observed than those of the CG. Relative abundance of potential probiotics including Prevotella_9, Lactococcus, and Cetobacterium was increased in the LB and HIB groups, accompanied by decreased the relative abundance of potentially pathogenic bacteria Mycoplasma. Overall, postbiotics of LCBS1 (heat-inactivated bacteria and cell-free extract) could be applied as a potential additive in bullfrog diet.

Postbiotics: The concept and their use in healthy populations.

The term postbiotic was recently defined by an panel of scientists convened by the International Scientific Association of Probiotics and Prebiotics as "a preparation of inanimate microorganisms and/or their components that confers a health benefit on the host." This definition focused on the progenitor microbial cell or cell fragments, not just metabolites, proteins or carbohydrates they might produce. Although such microbe-produced constituents may be functional ingredients of the preparation, they are not required to be present in a postbiotic according to this definition. In this context, terms previously used such as paraprobiotics, ghostbiotics, heat-inactivated probiotics, non-viable probiotics, cell fragments or cell lysates, among others, align with the term postbiotics as conceived by this definition. The applications of postbiotics to infant nutrition and pediatric and adult gastroenterology, mainly, are under development. Some applications for skin health are also underway. As postbiotics are composed of inanimate microorganisms, they cannot colonize the host. However, they can in theory modify the composition or functions of the host microbiota, although evidence for this is scarce. Clinical results are promising, but, overall, there is limited evidence for postbiotics in healthy populations. For example, postbiotics have been studied in fermented infant formulas. The regulation of the term postbiotic is still in its infancy, as no government or international agency around the world has yet incorporated this term in their regulation.

Binding and removal of polycyclic aromatic hydrocarbons in cold smoked sausage and beef using probiotic strains

The aim of this study is to bio-monitor the levels of 16 polycyclic aromatic hydrocarbons (PAHs) in cold smoked beef and sausages. The ability of probiotics to remove PAHs was also investigated as function of the cell viability (viable, non-viable and acid-treated cells), bacterial counts (107, 108, and 109 CFU/mL), pH (3, 5, and 7), and incubation time (6, 12, and 24 h). The results indicated a significant difference (p < 0.05) among the analyzed sausages and beef samples for the PAHs concentration. Non-viable probiotics achieved the highest PAHs reduction rates. Limosilactobacillus fermentum EMCC 1346 presented the lowest binding activity value (i.e. 41.10–56.80 %) for all PAHs, followed by Lacticaseibacillus rhamnosus EMCC 1105 with binding percentage of 50.40–65.80 %. On the other hand, the highest removal for all PAHs was achieved by Lactobacillus bulgaricus EMCC 1102 with binding rate of 60.50–76.80 %, at 109 CFU/mL, pH 7, after incubation for 24 h. The fortified sausages results revealed that L. bulgaricus EMCC 1102 cultures exhibited the maximum and significant reduction (p < 0.05) of PAHs with values of 44.71 µg/kg for the center part, compared to control non treated sausages (82.65 µg/kg). Regarding the sensorial profile, treated samples with probiotics led to a preference from the panelists, compared to control. Consequently, the results confirm that fermented probiotic suspension is a feasible future strategy to control PAHs levels in cold smoked meat stuffs.

The Concept of Postbiotics.

The scientific community has proposed terms such as non-viable probiotics, paraprobiotics, ghostbiotics, heat-inactivated probiotics or, most commonly, postbiotics, to refer to inanimate microorganisms and/or their components that confer health benefits. This article addresses the various characteristics of different definitions of ‘postbiotics’ that have emerged over past years. In 2021, the International Scientific Association for Probiotics and Prebiotics (ISAPP) defined a postbiotic as “a preparation of inanimate microorganisms and/or their components that confers a health benefit on the host”. This definition of postbiotic requires that the whole or components of inactivated microbes be present, with or without metabolic end products. The definition proposed by ISAPP is comprehensive enough to allow the development of postbiotics from different microorganisms, to be applied in different body sites, encouraging innovation in a promising area for any regulatory category and for companion or production animals, and plant or human health. From a technological perspective, probiotic products may contain inanimate microorganisms, which have the potential to impart a health benefit. However, their contribution to health in most cases has not been established, even if at least one probiotic has been shown to confer the same health benefit by live or inanimate cells.

Beer as a vehicle for probiotics

Background and Objective: Beer is one of the most consumed beverages worldwide that can be used to transfer probiotics to the host. The aim of this study was to generally review technological parameters incorporated in the production of probiotic beers. Probiotic beer production needs solving technical problems that are linked to processing stages. Although use of probiotics in fermented dairy products has been searched in available scientific literatures, beer is a relatively novel matrix for the incorporation of probiotics and hence a review on its capability as a probiotic carrier can be advantageous. Therefore, objective of the recent review was to investigate the most recent method for the production of probiotic beers. Furthermore, factors affecting the viability of probiotics in the final product were studied. Conclusion: Scientific literatures verified that probiotic beers could be produced with a few modifications from the non-probiotic beers. As probiotic species include poor growth abilities and probiotic viability is the most important factor considering a product as a probiotic product, multiple criteria for the production of probiotic beers include selecting an alcohol and acid-tolerant probiotic strain, administration of encapsulated probiotics, eliminating thermal and filtration processes, controlling oxygen concentration during fermentation process and after inoculation with probiotic strain, inhabiting severe acidic condition during the probiotic beer production and holding temperature below 5 ˚C during storage and transportation. However, several researches are needed to clarify limiting factors to achieve optimum conditions for the production of appropriate probiotic beers. However, incorporation of nonviable probiotics as alternate germs can be considered as a novel method for the production of health improving beers. Conflict of interest: The authors declare no conflict of interest.

Effects of non-viable Lactobacillus reuteri combining with 14-day standard triple therapy on Helicobacter pylori eradication: A randomized double-blind placebo-controlled trial.

Viable probiotics have shown effects on the eradication of Helicobacter pylori, but the role of non-viable probiotics in H. pylori eradication is unclear. This study aimed to evaluate the effects of non-viable Lactobacillus reuteri DSM17648 combining with 14-day standard triple therapy on H. pylori eradication. Two hundred treatment-naive H. pylori-positive adult patients were randomized equally to receive non-viable L. reuteri DSM17648 (LR group) or placebo for 4weeks, with the latter 2weeks treated together with triple therapy. The Gastrointestinal Symptom Rating Scale (GSRS) was completed before and after treatment. Stool samples were collected for 16S rRNA gene sequencing at week0, week2, and week8. Eradication rates in the LR group and the placebo group were 81.8% and 83.7% in ITT analysis (p=0.730), 86.2% and 87.2% in PP analysis (p=0.830), respectively. After treatment, the mean GSRS score decreased significantly in the LR group as compared with the placebo group (1.9±0.2 vs. 2.7±0.3; p=0.030). Significantly less patients in the LR group as compared with the placebo group reported abdominal distention (5.1% vs. 16.3%; p=0.010) and diarrhea (11.1% vs. 23.5%; p=0.022). The relative abundance of Proteobacteria phylum and Escherichia-Shigella genus in the placebo group was about 4.0-fold and 8.1-fold of that in the LR group at wk2, respectively. Significant changes of diversity and enhancements of Fusicatenibacter, Subdoligranulum, and Faecalibacterium were observed in the LR group compared with the placebo group. Supplementation of non-viable L. reuteri DSM17648 with triple therapy did not improve the eradication rate of H. pylori, but it helped to build up a beneficial microbial profile and reduced the frequencies of abdominal distention, diarrhea, and the GSRS score.

Paraprobiotics: A New Perspective for Functional Foods and Nutraceuticals.

Probiotics are live microorganisms that confer health benefits on the host. However, in recent years, several concerns on their use have been raised. In particular, industrial processing and storage of probiotic products are still technological challenges as these could severely impair cell viability. On the other hand, safety of live microorganisms should be taken into account, especially when administered to vulnerable people, such as the elderly and immunodeficient individuals. These drawbacks have enhanced the interest toward new products based on non-viable probiotics such as paraprobiotics and postbiotics. In particular, paraprobiotics, defined as “inactivated microbial cells (non-viable) that confer a health benefit to the consumer,” hold the ability to regulate the adaptive and innate immune systems, exhibit anti-inflammatory, antiproliferative and antioxidant properties and exert antagonistic effect against pathogens. Moreover, paraprobiotics can exhibit enhanced safety, assure technological and practical benefits and can also be used in products suitable for people with weak immunity and the elderly. These features offer an important opportunity to prompt the market with novel functional foods or nutraceuticals that are safer and more stable. This review provides an overview of central issues on paraprobiotics and highlights the urgent need for further studies aimed at assessing safety and efficacy of these products and their mechanisms of action in order to support decisions of regulatory authorities. Finally, a definition is proposed that unambiguously distinguishes paraprobiotics from postbiotics.

Oral Administration of Live and Dead Cells of Lactobacillus sakei proBio65 Alleviated Atopic Dermatitis in Children and Adolescents: a Randomized, Double-Blind, and Placebo-Controlled Study.

Several studies suggest that probiotics might be useful in the management of atopic dermatitis (AD). However, the efficacy and comparison between both the administration of viable and non-viable probiotics on alleviation of AD is not well studied. Therefore, the purpose of this study was to evaluate the effect of L. sakei proBio65 live and dead cells when administered (1 × 1010 cells/day) for 12weeks to children and adolescents (aged 3 to 18) with atopic dermatitis. In this randomized double-blind, placebo-controlled study, ninety patients were recruited and randomly allocated to either the L. sakei proBio65 live cells, L. sakei proBio65 dead cells, or placebo groups. Assessment of efficacy was based on the change in SCORing Atopic Dermatitis (SCORAD) score, Investigators Global Assessment (IGA) score, serum inflammatory markers such as the serum eosinophil (count), IgE, eosinophil cationic protein (ECP), CCL17 (thymus and activation-regulated chemokine [TARC]), and CCL27 (cutaneous T cell-attracting chemokine [CTACK]), and changes in skin condition (moisture and sebum) at baseline, week 6 and week 12. The SCORAD total score decreased in the live cells (p =0.0015) and dead cell group (p =0.0017) from the baseline after 12weeks, whereas there were no significant changes in the placebo group when compared with baseline. The skin sebum content increased in both the live cell (p <0.0001) and the dead cell group (p <0.0001), suggesting potential improvements in skin barrier functions. Current data suggested a positive improvement in alleviation of AD symptoms upon oral administration of L. sakei proBio65 in both viable and non-viable forms.

Optimization of Lactobacillus acidophilus cultivation using taro waste and evaluation of its biological activity.

In this study, taro waste (TW) was utilized for Lactobacillus acidophilus BCRC 14079 cultivation and the anti-tumor and immune-modulatory properties of heat-killed cells (HKCs), cytoplasmic fraction (CF), and exopolysaccharide (EPS) were evaluated. The optimum liquefaction enzyme dosage, temperature, and time determined by Box-Behnken design response surface methodology (BBD-RSM) were 9 mL/L of α-amylase, 79.2 °C, and 5 h of reaction, respectively. The optimum temperature and reaction time for saccharification were determined as 60 °C and 3 h. The optimum medium, CGMY1 medium, constitutes of TW hydrolysate containing 37 g/L of glucose, 25 g/L of corn gluten meal (CGM), and 1 g/L of yeast extract (YE). Results of MTT assay showed that HKCs and EPS from CGM medium exhibited the highest anti-proliferative in HT-29 (IC50 of HKCs, 467.25 μg/mL; EPS, 716.10 μg/mL) and in Caco-2 cells (IC50 of EPS, 741.60 μg/mL). Luciferase-based NF-ΚB and COX-2 systems indicated HKCs from CGM medium stimulated the highest expression of luciferin in both systems. The luciferase activities by using 100 and 500 μg/mL of HKCs from CGM were 24.30- and 45.83-fold in NF-ΚB system and 11.54- and 4.93-fold in COX-2 system higher than the control. In conclusion, this study demonstrated the potential of TW medium for L. acidophilus cultivation and the production of non-viable probiotics with enhanced biological activities.

Efficacy of pasteurised yoghurt in improving chronic constipation: A randomised, double-blind, placebo-controlled trial

One hundred and eighteen constipation subjects were fed a placebo or treatment (pasteurised yoghurt) for 7 weeks in a double-blind, randomised, placebo-controlled study. The results suggested that pasteurised yoghurt was effective in improving constipation. The subjects who ingested pasteurised yoghurt showed a significant increase in their defecation frequency following one week of the intervention. Constipation symptoms such as straining, lumpy or hard stool, and sensations of incomplete evacuation and anorectal blockage were all ameliorated. The numbers of faecal bifidobacteria and lactobacilli, and the short-chain fatty acid concentrations increased significantly in the treatment groups. In this study, pasteurised yoghurt with non-viable probiotics was found to exert a positive effect on constipation in adults, proving that heat-treated yoghurt can improve constipation. This function of pasteurised yoghurt may provide a new application for lactic acid bacteria.

Diarrhea in enterally fed patients

Diarrhea has great impact on enteral nutrition. The purpose of this review is to identify the factors leading to diarrhea during enteral nutrition and to provide the published updates on diarrhea prevention through nutritional intervention. Diarrhea in enteral fed patients is attributed to multiple factors, including medications (major contributor), infections, bacterial contamination, underlying disease, and enteral feeding. Diet management can alleviate diarrhea in enteral feeding. High content of fermentable oligosaccharides, disaccharides, and monosaccharides and polyols (FODMAPs) in enteral formula is postulated to induce diarrhea and lower FODMAPs formula may reduce the likelihood of diarrhea in enterally fed patients. Fiber-enriched formula can reduce the incidence of diarrhea and produce short-chain fatty acids for colonocytes. Ingesting prebiotics, nonviable probiotics or probiotic derivatives, and human lactoferrin may provide alternatives for reducing/preventing diarrhea. Enteral feeding is not generally considered the primary cause of diarrhea, which is frequently linked to prescribed medications. When diarrhea is apparent, healthcare members should evaluate the possible risk factors and systematically attempt to eliminate the underlying causes of diarrhea before reducing or suspending enteral feeding. Lower FODMAPs formula, prebiotics, probiotic derivatives, and lactoferrin may be used to manage enteral feeding-related diarrhea.

Probiotic viability – does it matter?

Probiotics are viable by definition, and viability of probiotics is often considered to be a prerequisite for the health benefits. Indeed, the overwhelming majority of clinical studies in the field have been performed with viable probiotics. However, it has also been speculated that some of the mechanisms behind the probiotic health effects may not be dependent on the viability of the cells and, therefore, is also possible that also non-viable probiotics could have some health benefits. The efficacy of non-viable probiotics has been assessed in a limited number of studies, with varying success. While it is clear that viable probiotics are more effective than non-viable probiotics and that, in many cases, viability is indeed a prerequisite for the health benefit, there are also some cases where it appears that non-viable probiotics could also have beneficial effects on human health.

Probiotic-Derived Factors: Probiotaceuticals?

Probiotics are broadly defined as living, nonpathogenic microorganisms (usually bacteria) which, when administered in sufficient numbers, exert a positive influence on host health. Mechanisms of probiotic action described to date include adhesion to the intestinal-lumen interface; competition with pathogens for nutrients, receptor binding, and colonization; enhancement of mucosal barrier function; promotion of innate and adaptive immune responses; elaboration of bacteriocins; and modulation of cell kinetics via alterations in the proliferation to apoptosis ratio, with further mechanisms of action gradually becoming elucidated (1). However, it is rare for any individual probiotic to act through a single mechanism, and its biological impact is further influenced by factors including dose, frequency of administration, and the composition of the enteric microflora. Perhaps not surprisingly, given the vast numbers of bacterial species, strains, and substrains in the microflora, the number of potential probiotics, and the complexity of their mechanism(s) of action, is equally diverse. Although Escherichia coli 1917, the first probiotic species to be described, was identified almost a hundred years ago, only recently has there been an upsurge in research into the properties of probiotic-derived factors. Such agents could potentially achieve therapeutic benefit while avoiding risks associated with the administration of live bacteria. It is in this context that Heuvelin et al. (2), in the January issue of this journal, explore the biological properties of factors released by the probiotic, Bifidobacterium breve C50. In a 2004 rodent study of experimental inflammatory bowel disease (IBD) utilizing VSL#3, a commercially available combination of 8 probiotic species, Rachmilewitz et al. (3) described protective effects mediated by probiotic DNA. Moreover, live microorganisms were not required to attenuate the colitis, as nonviable probiotics could mediate the antiinflammatory effect. Probiotic-derived factors have since been described as capable of exerting probiotic activities through each of the previously described mechanisms. However, it is important to distinguish between the concept of probiotic, which is necessarily based on the ingestion of live microorganisms, and the concept of microorganism-derived bioactive compounds that may have useful applications in nutrition and medicine. Bioactive compounds of bacterial or yeast origin, (antibiotics, for example), have been utilized in medicine for decades. Although there are many bacteria-derived products capable of inducing a health benefit, the concept of probiotic is only attributed to microorganisms administered as viable forms, providing the opportunity for a symbiotic relationship between the host, and resident, or in-transit, microorganisms.

Toll-like receptor 9 signaling mediates the anti-inflammatory effects of probiotics in murine experimental colitis

Background & Aims : We tested whether the attenuation of experimental colitis by live probiotic bacteria is due to their immunostimulatory DNA, whether toll-like receptor (TLR) signaling is required, and whether nonviable probiotics are effective. Methods : Methylated and unmethylated genomic DNA isolated from probiotics (VSL-3), DNAse-treated probiotics and Escherichia coli (DH5α) genomic DNA were administered intragastricly (i.g.) or subcutaneously (sc) to mice prior to the induction of colitis. Viable or γ-irradiated probiotics were administered i.g. to wild-type mice and mice deficient in different TLR or in the adaptor protein MyD88, 10 days prior to administration of dextran sodium sulfate (DSS) to their drinking water and for 7 days thereafter. Results : ntragastric and sc administration of probiotic and E. coli DNA ameliorated the severity of DSS-induced colitis, whereas methylated probiotic DNA, calf thymus DNA, and DNase-treated probiotics had no effect. The colitis severity was attenuated to the same extent by i.g. delivery of nonviable γ-irradiated or viable probiotics. Mice deficient in MyD88 did not respond to γ-irradiated probiotics. The severity of DSS-induced colitis in TLR2 and TLR4 deficient mice was significantly decreased by i.g. administration of γ-irradiated probiotics, whereas, in TLR9-deficient mice, γ-irradiated probiotics had no effect. Conclusions : The protective effects of probiotics are mediated by their own DNA rather than by their metabolites or ability to colonize the colon. TLR9 signaling is essential in mediating the anti-inflammatory effect of probiotics, and live microorganisms are not required to attenuate experimental colitis because nonviable probiotics are equally effective.

Adhesion of inactivated probiotic strains to intestinal mucus.

It has been suggested that probiotics should be viable in order to elicit beneficial health effects. Inactivation of probiotics has been suggested to interfere with the binding to the mucosa and thereby with the immune modulating activity of probiotics. The effect of different inactivation methods on the mucus adhesion of nine probiotic strains was studied. Inactivation by heat or gamma-irradiation generally decreased the adhesive abilities. However, heat treatment increased the adhesion of Propionibacterium freudenreichii and gamma-irradiation enhanced the adhesion of Lactobacillus casei Shirota. Inactivation by u.v. was not observed to modulate the adhesion of the tested strains and it was concluded to be the most appropriate method for studying non-viable probiotics and preparing control products.