Peptidoglycan derived from Lactobacillus rhamnosus MLGA up-regulates the expression of chicken -defensin 9 without triggering an inflammatory response

Modulation of gene expression in immune-related organs by in ovo stimulation with probiotics and prophybiotics in broiler chickens

In ovo stimulation has been studied intensively as an alternative to antibiotic use in poultry production. We investigated the potential use of a probiotic in combination with a phytobiotic as a prophybiotic for in ovo stimulation and reported its beneficial effects on the gut microbiome of broiler chickens. The current study further investigates the gene expression in the immune-related organs of these chickens to understand the tissue-specific immunomodulatory effects of the treatments. The selected prophybiotic (Leuconostoc mesenteroides with garlic aqueous extract) and its probiotic component alone were injected into ROSS308 chicken eggs on the 12th day of incubation, and gene expression in cecal tonsils, spleen, and liver at 35 days of age was determined using qPCR method. The relative expression of each treatment was compared to the positive control, chickens injected with physiological saline in ovo. The results displayed a downregulation of pro- and anti-inflammatory cytokines in the cecal tonsils of the probiotic group and the liver of the prophybiotic group. The spleen displayed upregulated AVBD1 in both groups and upregulated IL1-β in the probiotic group. The probiotic group displayed increased expression of genes related to metabolism of energy (COX16), protein (mTOR), and lipids (CYP46A1) whereas the prophybiotic group displayed reduced expression of genes related to cholesterol synthesis (SREBP1) and glucose transportation (SLC2A2) in the liver. In conclusion, Leuconostoc mesenteroides differentially modulated gene expression in chickens when administered in ovo in combination with garlic aqueous extract. Further in ovo studies with different prophybiotic combinations are required to optimize the benefits in broiler chickens.

Prebiotics, Probiotics and Postbiotics: The Changing Paradigm of Functional Foods

The rampant use of antibiotics has led to the emergence of multidrug resistance and is often coupled with gut dysbiosis. To circumvent the harmful impact of antibiotics, probiotics have emerged as an effective intervention. However, while the new probiotics are being added to the list, more recently, the nature and role of their counterparts, viz. prebiotics, postbiotics and parabiotics have also drawn considerable attention. As such, intricate relationships among these gut-biotics vis-à-vis their role in imparting health benefits is to be delineated in a holistic manner. Prebiotic dietary fibers are selectively fermented by probiotics and promote their colonization in the gut. The proliferation of probiotics leads to production of fermentation by-products (postbiotics) which affect the growth of enteropathogens by lowering the pH and producing inhibitory bacteriocins. After completing life-cycle, their dead remnants (parabiotics e.g. exopolysaccharides and cell wall glycoproteins) also inhibit adhesion and biofilm formation of pathogens on the gut epithelium. These beneficial effects are not just endemic to gut but a systemic response is witnessed at different gut-organ axes. Thus, to decipher the role of probiotics, it is imperative to unravel the interdependence between these components. This review elaborates on the recent advancements on various aspects of these gut-biotics and the mechanism of potential attributes like anti-oxidant, anti-inflammatory, anti-neoplastic, anti-lipidemic and anti-hyperglycemic benefits.

Mutanolysin-Digested Peptidoglycan of Lactobacillus reuteri Promotes the Inhibition of Porphyromonas gingivalis Lipopolysaccharide-Induced Inflammatory Responses through the Regulation of Signaling Cascades via TLR4 Suppression

Periodontitis is an oral infectious disease caused by various pathogenic bacteria, such as Porphyromonas gingivalis. Although probiotics and their cellular components have demonstrated positive effects on periodontitis, the beneficial impact of peptidoglycan (PGN) from probiotic Lactobacillus remains unclear. Therefore, our study sought to investigate the inhibitory effect of PGN isolated from L. reuteri (LrPGN) on P. gingivalis-induced inflammatory responses. Pretreatment with LrPGN significantly inhibited the production of interleukin (IL)-1β, IL-6, and CCL20 in RAW 264.7 cells induced by P. gingivalis lipopolysaccharide (LPS). LrPGN reduced the phosphorylation of PI3K/Akt and MAPKs, as well as NF-κB activation, which were induced by P. gingivalis LPS. Furthermore, LrPGN dose-dependently reduced the expression of Toll-like receptor 4 (TLR4), indicating that LrPGN inhibits periodontal inflammation by regulating cellular signaling cascades through TLR4 suppression. Notably, LrPGN exhibited stronger inhibition of P. gingivalis LPS-induced production of inflammatory mediators compared to insoluble LrPGN and proteinase K-treated LrPGN. Moreover, MDP, a minimal bioactive PGN motif, also dose-dependently inhibited P. gingivalis LPS-induced inflammatory mediators, suggesting that MDP-like molecules present in the LrPGN structure may play a crucial role in the inhibition of inflammatory responses. Collectively, these findings suggest that LrPGN can mitigate periodontal inflammation and could be a useful agent for the prevention and treatment of periodontitis.

Probiotic Escherichia coli Nissle 1917 protect chicks from damage caused by Salmonella enterica serovar Enteritidis colonization

As a foodborne pathogen of global importance, Salmonella enterica serovar Enteritidis (S. Enteritidis) is a threat to public health that is mainly spread by poultry products. Intestinal Enterobacteriaceae can inhibit the colonization of S. Enteritidis and are regarded as a potential antibiotic substitute. We investigated, in chicks, the anti-S. Enteritidis effects of Escherichia coli (E. coli) Nissle 1917, the most well-known probiotic member of Enterobacteriaceae. Eighty 1-d-old healthy female AA broilers were randomly divided into 4 groups, with 20 in each group, namely the negative control (group P), the E. coli Nissle 1917-treated group (group N), the S. Enteritidis-infected group (group S) and the E. coli Nissle 1917-treated and S. Enteritidis-infected group (group NS). From d 5 to 7, chicks in groups N and NS were orally gavaged once a day with E. coli Nissle 1917 and in groups P and S were administered the same volume of sterile PBS. At d 8, the chicks in groups S and NS were orally gavaged with S. Enteritidis and in groups P and N were administered the same volume of sterile PBS. Sampling was conducted 24 h after challenge. Results showed that gavage of E. coli Nissle 1917 reduced the spleen index, Salmonella loads, and inflammation (P < 0.05). It improved intestinal morphology and intestinal barrier function (P < 0.05). S. Enteritidis infection significantly reduced mRNA expression of angiotensin-converting enzyme 2 (ACE2) and solute carrier family 6-member 19 (SLC6A19) in the cecum and the content of Gly, Ser, Gln, and Trp in the serum (P < 0.05). Pretreatment with E. coli Nissle 1917 yielded mRNA expression of ACE2 and SLC6A19 in the cecum and levels of Gly, Ser, Gln, and Trp in the serum similar to that of uninfected chicks (P < 0.05). Additionally, E. coli Nissle 1917 altered cecum microbiota composition and enriched the abundance of E. coli, Lactobacillales, and Lachnospiraceae. These findings reveal that the probiotic E. coli Nissle 1917 reduced S. Enteritidis infection and shows enormous potential as an alternative to antibiotics.

Mechanisms and regulation of defensins in host defense

As a family of cationic host defense peptides, defensins are mainly synthesized by Paneth cells, neutrophils, and epithelial cells, contributing to host defense. Their biological functions in innate immunity, as well as their structure and activity relationships, along with their mechanisms of action and therapeutic potential, have been of great interest in recent years. To highlight the key research into the role of defensins in human and animal health, we first describe their research history, structural features, evolution, and antimicrobial mechanisms. Next, we cover the role of defensins in immune homeostasis, chemotaxis, mucosal barrier function, gut microbiota regulation, intestinal development and regulation of cell death. Further, we discuss their clinical relevance and therapeutic potential in various diseases, including infectious disease, inflammatory bowel disease, diabetes and obesity, chronic inflammatory lung disease, periodontitis and cancer. Finally, we summarize the current knowledge regarding the nutrient-dependent regulation of defensins, including fatty acids, amino acids, microelements, plant extracts, and probiotics, while considering the clinical application of such regulation. Together, the review summarizes the various biological functions, mechanism of actions and potential clinical significance of defensins, along with the challenges in developing defensins-based therapy, thus providing crucial insights into their biology and potential clinical utility.

Lactobacillus paracasei subsp. paracasei X12 Strain Induces Apoptosis in HT-29 Cells through Activation of the Mitochondrial Pathway

L. paracasei subsp. paracasei X12 was obtained from traditional cheese produced in northwestern China. In this study, we showed that whole peptidoglycan (WPG), extracted from L. paracasei subsp. paracasei X12, inhibited proliferation and induced apoptosis in HT-29 cells in a dose-dependent manner. In addition, WPG-induced apoptosis was associated with the loss of mitochondrial membrane potential (Ψm), the release of cytochrome c (Cyto-C) from mitochondrialto cytosolic spaces, activation of Caspase 3, and accumulation of intracellular reactive oxygen species (ROS). Finally, semi-quantitative RT-PCR showed that these events were accompanied by upregulation of proapoptotic genes (Bax or Bad) and downregulation of antiapoptotic genes (Bcl-xl). Taken together, our results demonstrated that WPG induced apoptosis in HT-29 cells through activation of the mitochondrial pathway. WPG exerted only minor toxicity upon noncancerous cells and therefore might be used as a natural agent in the treatment of cancer in future.

Host Defense Peptides in Nutrition and Diseases: A Contributor of Immunology Modulation

Host defense peptides (HDPs) are primary components of the innate immune system with diverse biological functions, such as antibacterial ability and immunomodulatory function. HDPs are produced and released by immune and epithelial cells against microbial invasion, which are widely distributed in humans, animals, plants, and microbes. Notably, there are great differences in endogenous HDP distribution and expression in humans and animals. Moreover, HDP expression could be regulated by exogenous substances, such as nutrients, and different physiological statuses in health and disease. In this review, we systematically assessed the regulation of expression and mechanism of endogenous HDPs from nutrition and disease perspectives, providing a basis to identify the specificity and regularity of HDP expression. Furthermore, the regulation mechanism of HDP expression was summarized systematically, and the differences in the regulation between nutrients and diseases were explored. From this review, we provide novel ideas targeted the immune regulation of HDPs for protecting host health in nutrition and practical and effective new ideas using the immune regulation theory for further research on protecting host health from pathogenic infection and excessive immunity diseases under the global challenge of the antibiotic-abuse-induced series of problems, including food security and microbial resistance.

Synbiotics: a New Route of Self-production and Applications to Human and Animal Health

Synbiotics are preparations in which prebiotics are added to probiotics to achieve superior performance and benefits on the host. A new route of their formation is to induce the prebiotic biosynthesis within the probiotic for synbiotic self-production or autologous synbiotics. The aim of this review paper is first to overview the basic concept and (updated) definitions of synergistic synbiotics, and then to focus particularly on the prebiotic properties of probiotic wall components while describing the environmental factors/stresses that stimulate autologous synbiotics, that is, the biosynthesis of prebiotic-forming microcapsule by probiotic bacteria, and finally to present some of their applications to human and animal health.

Probiotic Lactobacilli Do Not Protect Chickens against Salmonella Enteritidis Infection by Competitive Exclusion in the Intestinal Tract but in Feed, Outside the Chicken Host

Lactobacilli are commonly used as probiotics in poultry to improve production parameters and to increase chicken resistance to enteric infections. However, lactobacilli do not efficiently colonise the chicken intestinal tract, and also, their anti-infection effect in vivo is sometimes questionable. In this study, we therefore evaluated the potential of a mixture of four Lactobacillus species (L. salivarius, L. reuteri, L. ingluviei and L. alvi) for the protection of chickens against Salmonella Enteritidis infection. Whenever the chickens were inoculated by lactobacilli and S. Enteritidis separately, there was no protective effect of lactobacilli. This means that when lactobacilli and S. Enteritidis are exposed to each other as late as in the crop of chickens, lactobacilli did not influence chicken resistance to S. Enteritidis at all. The only positive effect was recorded when the mixture of lactobacilli and S. Enteritidis was used for the inoculation of feed and the feed was anaerobically fermented for 1 to 5 days. In this case, chickens fed such a diet remained S. Enteritidis negative. In vitro experiments showed that the protective effect was caused by acidification of feed down to pH 4.6 due to lactobacilli fermentation and was associated with S. Enteritidis inactivation. The probiotic effect of lactobacilli was thus expressed in the feed, outside the chicken host.