Effect of Probiotics on Central Nervous System Functions in Animals and Humans: A Systematic Review

Exploring the Role and Potential of Probiotics in the Field of Mental Health: Major Depressive Disorder

The field of probiotic has been exponentially expanding over the recent decades with a more therapeutic-centered research. Probiotics mediated microbiota modulation within the microbiota–gut–brain axis (MGBA) have been proven to be beneficial in various health domains through pre-clinical and clinical studies. In the context of mental health, although probiotic research is still in its infancy stage, the promising role and potential of probiotics in various mental disorders demonstrated via in-vivo and in-vitro studies have laid a strong foundation for translating preclinical models to humans. The exploration of the therapeutic role and potential of probiotics in major depressive disorder (MDD) is an extremely noteworthy field of research. The possible etio-pathological mechanisms of depression involving inflammation, neurotransmitters, the hypothalamic–pituitary–adrenal (HPA) axis and epigenetic mechanisms potentially benefit from probiotic intervention. Probiotics, both as an adjunct to antidepressants or a stand-alone intervention, have a beneficial role and potential in mitigating anti-depressive effects, and confers some advantages compared to conventional treatments of depression using anti-depressants.

Probiotics alleviate depressive behavior in chronic unpredictable mild stress rat models by remodeling intestinal flora

OBJECTIVE

To explore the effects of probiotics on depressive behavior in a chronic unpredictable mild stress (CUMS) rat model by remodeling intestinal flora.

METHODS

Twenty-four male SD rats aged 6-8 weeks were randomly divided into four groups: control group, depression group (CUMS), depression+paroxetine group (Paro) and depression+probiotics group (Pro). Sucrose preference, open field and forced swimming tests were used to assess depression-like behavior in rats. ELISA was used to detect the levels of adrenocorticotropic hormone (ACTH), and corticosterone, norepinephrine and 5-hydroxytryptamine in rat serum. Real-time PCR was used to determine the changes of Lactobacillus, Bifidobacterium, Enterococcus faecalis and Escherichia coli in rat cecum.

RESULTS

Compared with the control group, CUMS led to significant decreases of body weight, total traveled distance, duration in central area, immobility time, norepinephrine and 5-hydroxytryptamine contents in hippocampal tissues, as well as Lactobacillus and Bifidobacterium in the cecum. It also resulted in marked increases of the contents of E. faecalis and E. coli in the cecum, ACTH and corticosterone contents in the serum of rats. Paroxetine and probiotic treatment each diminished or prevented these changes.

CONCLUSION

By remodeling intestinal flora, probiotics can reduce the CUMS-induced depressive behavior of rats, increase the levels of norepinephrine and 5-hydroxytryptamine, and inhibit the expression of ACTH and corticosterone. Significantly, the effect of both paroxetine and probiotic on microorganisms is similar.

Gastrointestinal dysfunction in Parkinson's disease: molecular pathology and implications of gut microbiome, probiotics, and fecal microbiota transplantation

Gastrointestinal symptoms and gut dysbiosis may occur before the onset of motor symptoms in Parkinson's disease (PD). Prediagnostic and prodromal features, such as constipation and α-synuclein pathology, can be detected several years before the clinical diagnosis of PD and have the potential to develop as early PD biomarkers. Environmental toxins and gut dysbiosis may trigger oxidative stress and mucosal inflammation, and initiate α-synuclein accumulation in the enteric nervous system, early in PD. Chronic gut inflammation can lead to a leaky gut and systemic inflammation, neuro inflammation, and neuro degeneration via gut-vagus-brain signaling or through blood-brain barrier permeability. Concepts regarding the gut-brain signaling in PD pathogenesis are changing rapidly and more investigation is required. The gut microbiota interacts with the human body by modulating the enteric and central nervous systems, and immune activity. Understanding the immune responses between gut microbiota and human body might help in elucidating the PD pathogenesis. As changes in gut microbiota composition might be associated with different clinical phenotypes of PD, gut microbiota-modulating interventions, such as probiotics and fecal microbiota transplantation (FMT), have the potential to restore the gut dysbiosis, reduce inflammation, and possibly modulate the clinical PD phenotype.

The emerging role of probiotics in neurodegenerative diseases: new hope for Parkinson's disease?

Neurodegenerative disease etiology is still unclear, but different contributing factors, such as lifestyle and genetic factors are involved. Altered components of the gut could play a key role in the gut-brain axis, which is a bidirectional system between the central nervous system and the enteric nervous system. Variations in the composition of the gut microbiota and its function between healthy people and patients have been reported for a variety of human disorders comprising metabolic, autoimmune, cancer, and, notably, neurodegenerative disorders. Diet can alter the microbiota composition, affecting the gut-brain axis function. Different nutraceutical interventions have been devoted to normalizing gut microbiome dysbiosis and to improving biological outcomes in neurological conditions, including the use of probiotics. Preclinical and clinical investigations discussed in this review strengthen the correlation between intestinal microbiota and brain and the concept that modifying the microbiome composition may improve brain neurochemistry, modulating different pathways. This review will discuss the potential use of probiotics for Parkinson's disease prevention or treatment or as adjuvant therapy, confirming that gut microbiota modulation influences different pro-survival pathways. Future investigations in Parkinson's disease should consider the role of the gut-brain axis and additional comprehension of the underlying mechanisms is extremely necessary.

Rebuilding Microbiome for Mitigating Traumatic Brain Injury: Importance of Restructuring the Gut-Microbiome-Brain Axis

Traumatic brain injury (TBI) is a damage to the brain from an external force that results in temporary or permanent impairment in brain functions. Unfortunately, not many treatment options are available to TBI patients. Therefore, knowledge of the complex interplay between gut microbiome (GM) and brain health may shed novel insights as it is a rapidly expanding field of research around the world. Recent studies show that GM plays important roles in shaping neurogenerative processes such as blood-brain-barrier (BBB), myelination, neurogenesis, and microglial maturation. In addition, GM is also known to modulate many aspects of neurological behavior and cognition; however, not much is known about the role of GM in brain injuries. Since GM has been shown to improve cellular and molecular functions via mitigating TBI-induced pathologies such as BBB permeability, neuroinflammation, astroglia activation, and mitochondrial dysfunction, herein we discuss how a dysbiotic gut environment, which in fact, contributes to central nervous system (CNS) disorders during brain injury and how to potentially ward off these harmful effects. We further opine that a better understanding of GM-brain (GMB) axis could help assist in designing better treatment and management strategies in future for the patients who are faced with limited options.

Probiotics and potential applications for alternative poultry production systems

Concerns over animal welfare continue to be a critical component of law and policies associated with commercial food animal production. Social and market pressures are the driving forces behind the legislation and result in the change of poultry production management systems. As a result, the movement toward cage-free and aviary-based egg production systems has become standard practices. Cage-based systems being replaced by alternative methods that offer a suitable housing environment to meet or exceed poultry welfare needs and require different management, including the ban of antibiotics in poultry diets. For broiler production, pasture- raised and free-range management systems have become more popular. However, challenges remain from exposure to disease-causing organisms and foodborne pathogens in these environments. Consequently, probiotics can be supplemented in poultry diets as commercial feed additives. The present review discusses the impacts of these probiotics on the performance of alternative poultry production systems for improving food safety and poultry health by mitigating pathogenic organisms and improving egg and meat quality and production.

New Avenues for Parkinson's Disease Therapeutics: Disease-Modifying Strategies Based on the Gut Microbiota

Parkinson's disease (PD) is a multifactorial neurodegenerative disorder that currently affects 1% of the population over the age of 60 years, and for which no disease-modifying treatments exist. Neurodegeneration and neuropathology in different brain areas are manifested as both motor and non-motor symptoms in patients. Recent interest in the gut-brain axis has led to increasing research into the gut microbiota changes in PD patients and their impact on disease pathophysiology. As evidence is piling up on the effects of gut microbiota in disease development and progression, another front of action has opened up in relation to the potential usage of microbiota-based therapeutic strategies in treating gastrointestinal alterations and possibly also motor symptoms in PD. This review provides status on the different strategies that are in the front line (i.e., antibiotics; probiotics; prebiotics; synbiotics; dietary interventions; fecal microbiota transplantation, live biotherapeutic products), and discusses the opportunities and challenges the field of microbiome research in PD is facing.

The effects of psychobiotics on the microbiota-gut-brain axis in early-life stress and neuropsychiatric disorders

Psychobiotics are considered among potential avenues for modulating the bidirectional communication between the gastrointestinal tract and central nervous system, defined as the microbiota-gut-brain axis (MGBA). Even though causality has not yet been established, intestinal dysbiosis has emerged as a hallmark of several diseases, including neuropsychiatric disorders (NPDs). The fact that the microbiota and central nervous system are co-developing during the first years of life has provided a paradigm suggesting a potential role of psychobiotics for earlier interventions. Studies in animal models of early-life stress (ELS) have shown that they can counteract the pervasive effects of stress during this crucial developmental period, and rescue behavioral symptoms related to anxiety and depression later in life. In humans, evidence from clinical studies on the efficacy of psychobiotics at improving mental outcomes in most NPDs remain limited, except for major depressive disorder for which more studies are available. Consequently, the beneficial effect of psychobiotics on depression-related outcomes in adults are becoming clearer. While the specific mechanisms at play remain elusive, the effect of psychobiotics are generally considered to involve the hypothalamic-pituitary-adrenal axis, intestinal permeability, and inflammation. It is anticipated that future clinical studies will explore the potential role of psychobiotics at mitigating the risk developing NPDs in vulnerable individuals or in the context of childhood adversity. However, such studies remain challenging at present in terms of design and target populations; the profound impact of stress on the proper development of the MGBA during the first year of life is becoming increasingly recognized, but the trajectories post-ELS in humans and the mechanisms by which stress affects the susceptibility to various NPDs are still ill-defined. As psychobiotics are likely to exert both shared and specific mechanisms, a better definition of target subpopulations would allow to tailor psychobiotics selection by aligning mechanistic properties with known pathophysiological mechanisms or risk factors. Here we review the available evidence from clinical and preclinical studies supporting a role for psychobiotics at ameliorating depression-related outcomes, highlighting the knowledge gaps and challenges associated with conducting longitudinal studies to address outstanding key questions in the field.

The Nerves to Conduct a Multiple Sclerosis Crime Investigation

Multiple sclerosis (MS) is a chronic inflammatory neurodegenerative autoimmune disease characterized by the aberrant infiltration of immune cells into the central nervous system (CNS) and by the loss of myelin. Sclerotic lesions and various inhibitory factors hamper the remyelination processes within the CNS. MS patients typically experience gradual cognitive and physical disabilities as the disease progresses. The etiology of MS is still unclear and emerging evidence suggests that microbiome composition could play a much more significant role in disease pathogenesis than was initially thought. Initially believed to be isolated to the gut microenvironment, we now know that the microbiome plays a much broader role in various tissues and is essential in the development of the immune system. Here, we present some of the unexpected roles that the microbiome plays in MS and discuss approaches for the development of next-generation treatment strategies.

Physicochemical Analysis of Yogurt Produced by Leuconostoc mesenteroides H40 and Its Effects on Oxidative Stress in Neuronal Cells

Leuconostoc mesenteroides H40 (H40) was isolated from kimchi, and its probiotic properties and neuroprotective effect was evaluated in oxidatively stressed SH-SY5Y cells. H40 was stable in artificial gastric conditions and can be attached in HT-29 cells. In addition, H40 did not produce β-glucuronidase and showed resistant to several antibiotics. The conditioned medium (CM) was made using HT-29 cells refined with heat-killed probiotics (Probiotics-CM) and heated yogurts (Y-CM) to investigate the neuroprotective effect. Treatment with H40-CM not only increased cell viability but also significantly improved brain derived neurotropic factor (BDNF) expression and reduced the Bax/Bcl-2 ratio in oxidatively stress-induced SH-SY5Y cells. Besides, probiotic Y-CM significantly increased BDNF mRNA expression and decreased Bax/Bcl-2 ratio. The physicochemical properties of probiotic yogurt with H40 was not significantly different from the control yogurt. The viable cell counts of lactic acid bacteria in control and probiotic yogurt with H40 was 8.66 Log CFU/mL and 8.96 Log CFU/mL, respectively. Therefore, these results indicate that H40 can be used as prophylactic functional dairy food having neuroprotective effects.

Lactobacillus delbrueckii alleviates depression-like behavior through inhibiting toll-like receptor 4 (TLR4) signaling in mice

Background

The intestinal flora can influence behavior through the microbiota-gut-brain axis and is closely related to the occurrence and development of nervous system diseases such as depression. Probiotics like Lactobacillus may regulate the balance of the intestinal flora and play an active role in preventing and treating depression.

Methods

Eight-week-old C57BL/6J mice (n=32) were randomly and equally divided into a normal control group, a control + Lac group, a model group, and a model + Lac group. The model and model + Lac groups were intraperitoneally injected with 1.2 mg/kg lipopolysaccharide for 7 days, and the behavior of the mice was assessed 24 hours later. The normal and model groups received intragastric administration of saline daily, while the control + Lac and model + Lac groups were given 10⁹ cfu Lac intragastrically daily for 7 days. The inhibitory effect of Lac and its fermentation products on depression-related bacteria were examined in vitro.

Results

Lac effectively inhibited the production of depression-like behaviors in mice. The expression levels of zonula occludens-1 (ZO-1) and E-cadherin in the small intestine in the model group were significantly decreased, but Lac abrogated this effect. Overactivation of microglia and decreased expression of dopamine transporter (DAT) in brain tissues, which are closely related to depression, were also abrogated by Lac treatment. Furthermore, the expression of toll-like receptor 4 (TLR4) and nod-like receptor protein-3 (NLRP3), as well as the level of interleukin-1 beta (IL-1β) in the intestine and brain, were all significantly increased; however, these effects were subsequently abrogated by Lac. Moreover, Lac inhibited dysbiosis through its metabolites.

Conclusions

Lac has a remarkable antidepressant function, which it performs through the inhibition of dysbiosis (via its metabolites) and pattern recognition receptor TLR4 signaling.

The effects of co-administration of probiotics and prebiotics on chronic inflammation, and depression symptoms in patients with coronary artery diseases: a randomized clinical trial

BACKGROUND

It has been shown that dysbiosis might have a role in developing of chronic inflammation and depression. In this study, we are interested in exploring of anti-inflammatory and anti-depressant effects of Lactobacillus Rhamnosus G (LGG), a probiotic strain, alone or in combination with a prebiotic, Inulin, in patients with coronary artery disease (CAD).

METHODS

This randomized, double-blind clinical trial was held on 96 patients with CAD. Patients were randomly allocated into four different groups: LGG [a capsule/day, contained 1.9 × 10⁹ colony-forming unit of Lactobacillus Rhamnosus G], inulin (15 g/day), co-supplemented (LGG and inulin), and placebo. Participants consumed the supplements for two months. Beck Depression Inventory (BDI), MacNew questionnaire and Spielberger state-trait anxiety inventory (STAI-Y) were used to assess depression, quality of life and anxiety, respectively. Serum levels of C-reactive protein (hs-CRP), lipopolysaccharide (LPS), tumor necrosis factor (TNF)-α, and Interleukin (IL)-10 were also measured.

RESULTS

Probiotic-Inulin Co-supplementation significantly decreased BDI (-11.52 ± 0+3.20 vs. +2.97 ± 0.39, P = 0.001), STAI-state (-17.63 ± 3.22 vs. -0.60 ± 0.33, P = 0.021), and STAI-trait (-24.31 ± 7.41 vs. -1.45 ± 0.66, P = 0.020) scores, hs-CRP (-1.69 ± 0+66 vs. +0.82 ± 0.39 mg/dL, P = 0.020), LPS (-22.02 ± 5.40 vs. +0.31 ± 0.18 (EU/L), P = 0.047), and TNF-α (-25.05 ± 7.41 vs. +0.79 ± 0.71 (ng/L), P = 0.032) in comparison to placebo.

CONCLUSION

Co-supplementation of probiotics and inulin in CAD subjects for eight weeks had beneficial effects on depression, anxiety, and inflammatory biomarkers. Adding inulin to probiotic supplements improved psychological outcomes and inflammatory biomarkers more effectively than two supplements separately.Trial registration: Iranian Registry of Clinical Trials identifier: IRCT20180712040438N4..

Effects of the antibiotic rifaximin on cortical functional connectivity are mediated through insular cortex

It is well-known that antibiotics affect commensal gut bacteria; however, only recently evidence accumulated that gut microbiota (GM) can influence the central nervous system functions. Preclinical animal studies have repeatedly highlighted the effects of antibiotics on brain activity; however, translational studies in humans are still missing. Here, we present a randomized, double-blind, placebo-controlled study investigating the effects of 7 days intake of Rifaximin (non-absorbable antibiotic) on functional brain connectivity (fc) using magnetoencephalography. Sixteen healthy volunteers were tested before and after the treatment, during resting state (rs), and during a social stressor paradigm (Cyberball game—CBG), designed to elicit feelings of exclusion. Results confirm the hypothesis of an involvement of the insular cortex as a common node of different functional networks, thus suggesting its potential role as a central mediator of cortical fc alterations, following modifications of GM. Also, the Rifaximin group displayed lower connectivity in slow and fast beta bands (15 and 25 Hz) during rest, and higher connectivity in theta (7 Hz) during the inclusion condition of the CBG, compared with controls. Altogether these results indicate a modulation of Rifaximin on frequency-specific functional connectivity that could involve cognitive flexibility and memory processing.

Interplay of Good Bacteria and Central Nervous System: Cognitive Aspects and Mechanistic Considerations

The human gastrointestinal tract hosts trillions of microorganisms that is called “gut microbiota.” The gut microbiota is involved in a wide variety of physiological features and functions of the body. Thus, it is not surprising that any damage to the gut microbiota is associated with disorders in different body systems. Probiotics, defined as living microorganisms with health benefits for the host, can support or restore the composition of the gut microbiota. Numerous investigations have proved a relationship between the gut microbiota with normal brain function as well as many brain diseases, in which cognitive dysfunction is a common clinical problem. On the other hand, increasing evidence suggests that the existence of a healthy gut microbiota is crucial for normal cognitive processing. In this regard, interplay of the gut microbiota and cognition has been under focus of recent researches. In the present paper, I review findings of the studies considering beneficial effects of either gut microbiota or probiotic bacteria on the brain cognitive function in the healthy and disease statuses.

Environmental Enrichment as a Strategy to Confront Social Isolation Under the COVID-19 Pandemic

The moment of social isolation experienced by the world population due to the COVID-19 pandemic tends to trigger behavioral changes of different orders and on an exponential scale, regardless of social class, age, gender, or ethnicity. Environmental enrichment presents itself as an important strategy to face the social isolation imposed by the pandemic, in order to act as an important agent of induction of biological factors for cognitive and emotional development, favoring a better possibility of adaptation to isolation.

Probiotic Lactobacillus fermentum strain JDFM216 improves cognitive behavior and modulates immune response with gut microbiota

Increasing evidence indicates that alterations in gut microbiota are associated with mammalian development and physiology. The gut microbiota has been proposed as an essential player in metabolic diseases including brain health. This study aimed to determine the impact of probiotics on degenerative changes in the gut microbiota and cognitive behavior. Assessment of various behavioral and physiological functions was performed using Y-maze tests, wheel running tests, accelerated rotarod tests, balance beam tests, and forced swimming tests (FSTs), using adult mice after 50 weeks of administering living probiotic bacterium Lactobacillus fermentum strain JDFM216 or a vehicle. Immunomodulatory function was investigated using immune organs, immune cells and immune molecules in the mice, and gut microbiota was also evaluated in their feces. Notably, the L. fermentum JDFM216-treated group showed significantly better performance in the behavior tests (P < 0.05) as well as improved phagocytic activity of macrophages, enhanced sIgA production, and stimulated immune cells (P < 0.05). In aged mice, we observed decreases in species belonging to the Porphyromonadaceae family and the Lactobacillus genus when compared to young mice. While administering the supplementation of L. fermentum JDFM216 to aged mice did not shift the whole gut microbiota, the abundance of Lactobacillus species was significantly increased (P < 0.05). Our findings suggested that L. fermentum JDFM216 also provided beneficial effects on the regulation of immune responses, which has promising implications for functional foods. Taken together, L. fermentum JDFM216 could confer the benefit of improving health with enhanced cognition, physiological behavior, and immunity by modulating the gut microbiota.

Potential role of the gut microbiota in neuromyelitis optica spectrum disorder: Implication for intervention

The gut microbiota plays an important role in the occurrence and development of neuroimmunological diseases. Neuromyelitis optica spectrum disorder (NMOSD) is an autoimmune disease of the central nervous system that is characterized by the peripheral production of the disease-specific serum autoantibody aquaporin-4 (AQP4)-IgG. Recently, accumulating evidence has provided insights into the associations of gut microbiota dysbiosis and intestinal mucosal barrier destruction with NMOSD, but the underlying pathogenesis remains unclear. Thus, a microbiota intervention might be a potential therapeutic strategy for NMOSD by regulating the gut microbiota, repairing the intestinal mucosal barrier, and modulating intestinal immunity and peripheral immunity.

Colon-delivered short-chain fatty acids attenuate the cortisol response to psychosocial stress in healthy men: a randomized, placebo-controlled trial

Short-chain fatty acids (SCFAs) are products of microbial fermentation of dietary fiber in the colon and may mediate microbiota-gut-brain communication. However, their role in modulating psychobiological processes that underlie the development of stress- and anxiety-related disorders is not mechanistically studied in humans. In this triple-blind, randomized, placebo-controlled intervention trial, we examine in a parallel group design the effects of 1-week colonic SCFA-mixture delivery in doses equivalent to fermentation of 10 g or 20 g of arabinoxylan oligosaccharides on responses to psychosocial stress and fear tasks in 66 healthy men. We demonstrate that low and high doses of SCFAs significantly attenuate the cortisol response to psychosocial stress compared to placebo. Both doses of SCFAs increase serum SCFA levels and this increase in circulating SCFAs co-varies significantly with the attenuation of the cortisol response to psychosocial stress. Colonic SCFA delivery does not modulate fecal SCFA concentrations, serum brain-derived neurotrophic factor, cortisol awakening response, fear learning and extinction, or subjective mood ratings. These results demonstrate that colon-delivered SCFAs modulate hypothalamic-pituitary-adrenal axis reactivity to psychosocial stress, thereby supporting their hypothesized role in microbiota-gut-brain communication.

Probiotic Treatment in Individuals with Euthymic Bipolar Disorder: A Pilot-Study on Clinical Changes and Compliance

The importance of the microbiome for psychological well-being has gained rising interest in the last decade. A strategy to examine the role of the microbiome in different diseases is the intake of supplements that modulate the gut microbiome. Despite promising results in animal studies, research in humans is sparse to date and especially in individuals with psychiatric disorders almost missing. The current report of the ProbioBIP-one pilot study aims at describing general effects of the intake of the probiotic OMNi-BiOTiC Stress repair® on psychological parameters as well as gastrointestinal symptoms and general compliance in a cohort of euthymic individuals with bipolar disorder (BD), receiving daily probiotic treatment over a time period of 3 months. Twenty-seven individuals with BD took part in the present study (mean age = 50.7 years, SD = 12.2; females 40.7%). In sum, there was a high compliance rate with 81.5% of the study participants completing all 3 study visits and 85% of planned probiotic ingestions taken. Gastrointestinal problems were prevalent in more than half of the patients at the time of inclusion (t1). Expectedly, in the whole cohort, a high proportion of study participants experienced changes concerning digestion during probiotic treatment, around one third reported positive changes (reduced flatulence and easier and more frequent bowel movements) after 1 month (t2) and further after 3 months (t3). In contrast, a smaller part of study participants reported gastrointestinal discomfort after 1 and after 3 months (mainly flatulence and obstipation). We found a significantly reduced cognitive reactivity to sad mood between t2 and t3 indicating that participants under probiotic supplementation perceived themselves to be less distracted by ruminative thoughts. Further changes in psychiatric symptoms were small due to the euthymic state and already low scoring at the time of inclusion. Nevertheless, we found a significant symptom reduction in the rating scales measuring manic symptoms. From a clinical point of view, probiotic supplementation might provide a well-tolerated tool to positively influence gastrointestinal quality of life as well as mental and somatic health, cognition and immune response and potentially have effects on psychiatric symptoms.

Paediatric functional abdominal pain disorders

Paediatric functional abdominal pain disorders, currently referred to as disorders of gut-brain interaction, comprise irritable bowel syndrome, functional dyspepsia, abdominal migraine and functional abdominal pain not otherwise specified, as defined by the Rome IV diagnostic criteria. Functional abdominal pain disorders are common disorders with a prevalence of 3-16% depending on country, age and sex. A greater understanding of aetiopathogenesis and pathophysiology is emerging and includes intestinal components (inflammation, motility and the microbiota), central factors (psychological aspects, sensitization and/or differences in connectivity or activity of certain brain regions) as well as extrinsic factors (infections). In particular, the timing of disruption of the microbiota-gut-brain axis seems to be important. Diagnosis is challenging but is primarily based on clinical symptoms and exclusion of other organic causes, with an emphasis on avoiding unnecessary invasive diagnostic procedures. The available pharmacological interventions are limited in children and, therefore, management has focused on combined approaches, including mind-targeted interventions (hypnotherapy and cognitive behavioural therapy), diet (probiotics) and percutaneous electrical nerve field stimulation. The evidence for their clinical efficacy, although limited, is favourable, with positive impacts on symptoms and overall quality of life. The coming decades hold promise for improved understanding and management of these enigmatic disorders.

Gut Microbiota and Epilepsy: A Systematic Review on Their Relationship and Possible Therapeutics

Dysbiosis of gut microbiota may lead to a range of diseases including neurological disorders. Thus, it is hypothesized that regulation of the intestinal microbiota may prevent or treat epilepsy. The purpose of this systematic review is to evaluate the evidence investigating the relationship between gut microbiota and epilepsy and possible interventions. A systematic review of the literature was done on four databases (PubMed, Scopus, EMBASE, and Web of Science). Study selection was restricted to original research articles while following the PRISMA guidelines. Six studies were selected. These studies cohesively support the interaction between gut microbiota and epileptic seizures. Gut microbiota analysis identified increases in Firmicutes, Proteobacteria, Verrucomicrobia, and Fusobacteria with decreases in Bacteroidetes and Actinobacteria in epileptic patients. Ketogenic diet, probiotics, and fecal microbiota transplantation (FMT) improved the dysbiosis of the gut microbiota and seizure activity. However, the studies either had a small sample size, lack of subject variability, or short study or follow-up period, which may question their reliability. Nevertheless, these limited studies conclusively suggest that gut microbiota diversity and dysbiosis may be involved in the pathology of epilepsy. Future studies providing more reliable and in depth insight into the gut microbial community will spark promising alternative therapies to current epilepsy treatment.

Psychobiotic Effects of Multi-Strain Probiotics Originated from Thai Fermented Foods in a Rat Model

This work aimed to investigate the psychobiotic effects of six bacterial strains on the mind and behavior of male Wistar rats. The probiotic (PRO) group (n=7) were rats pre-treated with antibiotics for 7 days followed by 14-day probiotic administration, antibiotics (ANT) group (n=7) were rats treated with antibiotics for 21 days without probiotics. The control (CON) group (n=7) were rats that received sham treatment for 21 days. The six bacterial strains with probiotic properties were mostly isolated from Thai fermented foods; Pedicoccus pentosaceus WS11, Lactobacillus plantarum SK321, L. fermentum SK324, L. brevis TRBC 3003, Bifidobacterium adolescentis TBRC 7154 and Lactococcus lactis subsp. lactis TBRC 375. The probiotics were freeze-dried into powder (6×109 CFU/5 g) and administered to the PRO group via oral gavage. Behavioral tests were performed. The PRO group displayed significantly reduced anxiety level and increased locomotor function using a marble burying test and open field test, respectively and significantly improved short-term memory performance using a novel object recognition test. Antibiotics significantly reduced microbial counts in rat feces in the ANT group by 100 fold compared to the PRO group. Probiotics significantly enhanced antioxidant enzymatic and non-enzymatic defenses in rat brains as assessed using catalase activity and ferric reducing antioxidant power assay, respectively. Probiotics also showed neuroprotective effects with less pyknotic cells and lower frequency of vacuolization in cerebral cortex. This multi-strain probiotic formulation from Thai fermented foods may offer a potential to develop psychobiotic-rich functional foods to modulate human mind and behaviors.

Glycated milk protein fermented with Lactobacillus rhamnosus ameliorates the cognitive health of mice under mild-stress condition

This study aimed to investigate the effects of glycated milk casein (Gc) fermented with Lactobacillus rhamnosus 4B15 (FGc) on the intestinal microbiota and physiological and behavioral properties in mice under chronic stress. Mice were administered Gc or FGc for 10 weeks and then exposed to unpredictable chronic mild stress (UCMS) for 7 weeks. FGc administration restored alterations of gut microbiota induced by UCMS. Moreover, FGc significantly reduced the stress-induced increase in serum corticosterone and decrease in serotonin levels. Anxiety-like behaviors induced by UCMS were also significantly decreased in the FGc group. UCMS-induced dysregulation of gene and protein expression related to neuroendocrine function, neuronal development, and inflammation, and gut-blood-brain barrier function was controlled by FGc pre-treatment. These results strongly suggest the protective effects of FGc targeting of intestinal microbiota for abnormal brain activity, which is consistent with the view that FGc plays an important role in regulating stress-related gut-brain axis disorders.

Effects of a Psychobiotic Supplement on Serum Brain-derived Neurotrophic Factor Levels in Depressive Patients: A Post Hoc Analysis of a Randomized Clinical Trial

Background/Aims

Psychobiotics are probiotics or prebiotics that, upon ingestion in adequate amounts, yield positive influence on mental health via microbiota-gut-brain axis regulation to modulate the circulating cytokines, chemokines, neurotransmitters, or neurotrophins levels. We have recently shown that a psychobiotic combination (Lactobacillus helveticus R0052 and Bifidobacterium longum R0175; CEREBIOME) significantly improved depression symptoms in patients with depression. Recent animal data suggest the influence of the gut microbiota on brain-derived neurotrophic factor (BDNF), which was shown to correlate with antidepressant response in depressive patients. Therefore, we conducted this exploratory post hoc analysis of BDNF levels to clarify the mechanism of action of this psychobiotic in our cohort.

Methods

Our study was a double-blind, randomized controlled trial of patients with low-to-moderate depression receiving either a probiotic combination, prebiotic or placebo. From the 110 patients randomized in the trial, 78 were included in this post hoc analysis (probiotic, n = 28; prebiotic and placebo, n = 25). We compared serum BDNF levels from participants at baseline and endpoint, and assessed the Pearson correlation between depression severity and BDNF levels for each intervention.

Results

We found that post-intervention BDNF levels were significantly different between groups (P < 0.001). Furthermore, BDNF levels increased significantly in the probiotic group compared to both the prebiotic (P < 0.001) and placebo groups (P = 0.021), which inversely correlated with depression severity compared to placebo (ANOVA/ANCOVA, P = 0.012; Pearson, r = -0.79, P < 0.001). In the prebiotic group, BDNF levels reduced but not significantly compared with placebo group (P > 0.05).

Conclusion

Eight-week supplementation with B. longum and L. helveticus in depressive patients improved depression symptoms, possibly by increasing BDNF levels.

Gut microbiome and multiple sclerosis: New insights and perspective

The human gastrointestinal microbiota, also known as the gut microbiota living in the human gastrointestinal tract, has been shown to have a significant impact on several human disorders including rheumatoid arthritis, diabetes, obesity, and multiple sclerosis (MS). MS is an inflammatory disease characterized by the destruction of the spinal cord and nerve cells in the brain due to an attack of immune cells, causing a wide range of harmful symptoms related to inflammation in the central nervous system (CNS). Despite extensive studies on MS that have shown that many external and genetic factors are involved in its pathogenesis, the exact role of external factors in the pathophysiology of MS is still unclear. Recent studies on MS and experimental autoimmune encephalomyelitis (EAE), an animal model of encephalitis, have shown that intestinal microbiota may play a key role in the pathogenesis of MS. Therefore, modification of the intestinal microbiome could be a promising strategy for the future treatment of MS. In this study, the characteristics of intestinal microbiota, the relationship between intestine and brain despite the blood-brain barrier, various factors involved in intestinal microbiota modification, changes in intestinal microbial composition in MS, intestinal microbiome modification strategies, and possible use of intestinal microbiome and factors affecting it have been discussed.

Effect of regulating gut microbiota using probiotics on functional changes in the brain: protocol for a systematic review

INTRODUCTION

There is a growing number of randomised controlled trials (RCTs) that focus on functional changes in the brain detected by functional MRI (fMRI) and gut microbiota composition changes after using probiotics.However, the effect of probiotics on functional changes in the brain through gut microbiota remains controversial in existing RCTs. Furthermore, to our knowledge, there is no systematic review to evaluate the effect of probiotics on functional changes in the brain through gut microbiota. Therefore, we aim to summarise literatures evaluating the potential association between probiotics, gut microbiota and functional changes in the brain to elucidate whether probiotics influence gut microbiota and affect functional changes in the brain through gut microbiota.

METHODS AND ANALYSIS

China National Knowledge Infrastructure, Wanfang Data, VIP Databases (the Chongqing VIP Chinese Science and Technology Periodical Database), SinoMed, PubMed, Web of Science, MEDLINE (The National Library of Medicine), EMBASE (Excerpt Medica Database), Scopus, the Cochrane Central Register of Controlled Trials and ClinicalTrials.gov will be searched until July 2019. The Grey Literature in Europe (OpenSIGLE) database and Google search engine will also be used. The reference lists of each included study will be reviewed to determine whether there are any further relevant studies. RCTs using probiotics compared with a placebo/control will be included. We will use risk of bias assessment and the Grading of Recommendations Assessment, Development and Evaluation (GRADE) system to assess the quality of evidence. The results of the systematic review will be synthesised narratively in the domains of the three primary outcome measures: (1) Increased/decreased activity in brain regions or altered functional connectivity (FC) of brain detected by fMRI and their association with changes in behaviour, gastrointestinal/emotional symptoms after using probiotics. (2) Changes in composition and diversity of the gut microbiota and their association with changes in behaviour, gastrointestinal/emotional symptoms after using probiotics. (3) Increased/decreased activity in brain regions or altered FC of brain detected by fMRI and the changes in composition or diversity of the gut microbiota after administration of probiotics.

ETHICS AND DISSEMINATION

The results will be disseminated through a peer-reviewed publication. As no private and confidential patient data will be included in the reporting, there are no ethical considerations associated with this protocol.

PROSPERO REGISTRATION NUMBER

CRD42019145114.

The Effects of Probiotics and Prebiotics on Mental Disorders: A Review on Depression, Anxiety, Alzheimer, and Autism Spectrum Disorders

BACKGROUND

Probiotics and their nutrient sources (prebiotics) have been shown to have positive effects on different organs of the host. The idea of their potential benefits on Central Nervous Systems (CNS) and the incidence of Anxiety, Schizophrenia, Alzheimer, Depression, Autism, and other mental disorders has proposed a new category of medicines called "psychobiotic" which is hoped to be of low-side effect anti-inflammatory, antidepressant, and anti-anxiety constitutes.

OBJECTIVE

In the current review, we present valuable insights into the complicated interactions between the GI microbiota (especially in the colon), brain, immune and central nervous systems and provide a summary of the main findings of the effects of pro- and prebiotics on important mental disorders from the potential mechanisms of action to their application in clinical practice.

METHODS

Google Scholar, Pub Med, Scopus, and Science Direct databases were searched using following key words: "probiotics", "prebiotics", "mental disorders", "psychological disorders", "depression", "anxiety", "stress", "Alzheimer" and "autism spectrum". The full text of potentially eligible studies was retrieved and assessed in detail by the reviewers. Data were extracted and then summarized from the selected papers.

RESULTS

The results of the provided evidence suggest that probiotic and prebiotics might improve mental function via several mechanisms. The beneficial effects of their application in Depression, Anxiety, Alzheimer and autism spectrum diseases have also been supported in clinical studies.

CONCLUSION

Pro and prebiotics can improve mental health and psychological function and can be offered as new medicines for common mental disorders, however, more clinical studies are necessary to conduct regarding the clinical significance of the effects and their bioequivalence or superiority against current treatments.

Salmonella Strain Specificity Determines Post-typhoid Central Nervous System Complications: Intervention by Lactiplantibacillus plantarum at Gut-Brain Axis

Neurological complications occurring due to Salmonella infection in some typhoid patients remain a relatively unexplored serious complication. This study firstly aimed to explore whether disseminative ability of Salmonella from gut to brain is strain specific or not and on the basis of bacterial load, histopathology, and behavioral changes, it was observed that Salmonella enterica serovar Typhimurium NCTC 74 did not cause brain infection in murine model in contrast to Salmonella Typhimurium SL1344. Simultaneously, alarming escalation in antimicrobial resistance, making the existing antibiotics treatment inefficacious, prompted us to evaluate other bio-compatible strategies as a potential treatment option. In this context, the role of gut microbiota in influencing behavior, brain neurochemistry, and physiology by modulating key molecules associated with gut-brain axis has captured the interest of the scientific community. Followed by in vitro screening of potential probiotic strains for beneficial attributes, efficacy of the selected strain was systematically evaluated at various levels of gut-brain axis against Salmonella induced brain infection. Analysis of behavioral (depression, anxiety, and locomotor), neurochemical [gamma amino butyric acid and acetylcholinesterase (AChE)], neuropathological (brain and intestinal histology; bacterial burden), and immunohistochemical studies (tight junction proteins expression) revealed its role in preventing serious manifestations and proving its potential as "psychobiotic." To the best of our knowledge, this is the first report elaborating strain specificity of Salmonella in causing post-typhoidal neurological manifestations and simultaneous use of probiotic in managing the same by influencing the pathophysiology at gut-brain axis.

The Feasibility and Efficacy of a Brief Integrative Treatment for Adults With Depression and/or Anxiety: A Randomized Controlled Trial

The aim of this study was to investigate the efficacy and suitability of a brief integrative intervention, Personalized Integrative Therapy (PI Therapy), for the treatment of adult depression and/or anxiety. In this 6-week, 3-arm, parallel-group, randomized trial, PI Therapy delivered alone or with nutritional supplements (PI Therapy + Supps) was compared to cognitive behavior therapy (CBT) in 48 adults with depression and/or anxiety. All treatments were delivered as a 1-day workshop plus 6 weeks of reminder phone text messages to reinforce topics and skills covered in the workshop. Affective symptoms decreased significantly and to the same extent in all 3 conditions. At the end of treatment, 33% to 58% of participants reported levels of depressive symptoms in the normal range, and 50% to 58% reported nonclinical levels of anxiety. Compared to CBT and PI Therapy, PI Therapy + Supps was associated with significantly greater improvements in sleep quality. These findings suggest that a brief integrative intervention with or without supplements was comparable to CBT in reducing affective symptoms in adults with depression and/or anxiety. However, sleep quality improved only in the PI Therapy + Supps condition. These findings will require replication with a larger cohort.

Lactobacillus rhamnosus GG and Bifidobacterium bifidum TMC3115 Can Affect Development of Hippocampal Neurons Cultured In Vitro in a Strain-Dependent Manner

This study examined whether Lactobacillus rhamnosus GG (LGG) and Bifidobacterium bifidum TMC3115 (TMC3115) could morphologically or physiologically influence hippocampal neuronal development in vitro. Hippocampal neurons cultured in vitro were exposed to live or heat-inactivated LGG or TMC3115 for either 6 or 24 h. Neuronal morphological changes and drebrin (DRB) and synaptophysin (SYP) protein levels were monitored using immunofluorescence. And the levels of DRB, SYP, and brain-derived neurotrophic factor (BDNF), and cAMP-response element binding protein (CREB) mRNA were detected using RT-PCR. The BDNF, CREB, and phosphorylated-CREB (P-CREB) protein levels were detected by extraction-enzyme-linked immunosorbent assay (ELISA) or Western blot assays. Heat-inactivated LGG and TMC3115 could enhance neuron viability, DRB and SYP protein levels, and BDNF mRNA level were significantly altered after exposure to the tested bacteria with 6 h or 24 h. There were no significant differences in neuronal morphology or DRB, SYP, or CREB mRNA levels among the groups following bacterial exposure. However, following exposure of live TMC3115 for 24 h, the neuronal BDNF and P-CREB protein levels were both significantly up-regulated as detected by western blot assays. These results demonstrated that LGG and TMC3115 could affect neuronal viability, along with hippocampal synaptic and functional development, in a strain-dependent manner, which may also be closely associated with the physiological and culture conditions of each strain. Up-regulated P-CREB may be one of the underlying mechanisms by which the bacteria, especially neurons following exposure of live TMC3115 for 24 h, are able to regulate neuronal BDNF protein production.

Clinical Trials of Probiotic Strains in Selected Disease Entities

Probiotics are live microorganisms which when administered in adequate amounts confer a health benefit on the host. Although their mechanism of action is not clearly explained, it is known that they positively modulate the immune system, which leads to immunity potentiation. A number of studies prove that probiotics strengthen cognitive functions, reduce anxiety, and regulate the lipid metabolism in the human body. Probiotics used in humans are most often of the Lactobacillus and Bifidobacterium species. However, as more research is conducted, new species with beneficial, probiotic properties are being discovered. This paper provides a review of available information about the influence of probiotics on human health. It summarizes the current knowledge on the mechanism of action of probiotics as well as clinical trial results proving their efficacy in allergic, neurodegenerative, and cardiac diseases. This review also discusses the data concerning the safety of probiotics in clinical treatment.

Rodent models of post-traumatic stress disorder: behavioral assessment

Although the etiology and expression of psychiatric disorders are complex, mammals show biologically preserved behavioral and neurobiological responses to valent stimuli which underlie the use of rodent models of post-traumatic stress disorder (PTSD). PTSD is a complex phenotype that is difficult to model in rodents because it is diagnosed by patient interview and influenced by both environmental and genetic factors. However, given that PTSD results from traumatic experiences, rodent models can simulate stress induction and disorder development. By manipulating stress type, intensity, duration, and frequency, preclinical models reflect core PTSD phenotypes, measured through various behavioral assays. Paradigms precipitate the disorder by applying physical, social, and psychological stressors individually or in combination. This review discusses the methods used to trigger and evaluate PTSD-like phenotypes. It highlights studies employing each stress model and evaluates their translational efficacies against DSM-5, validity criteria, and criteria proposed by Yehuda and Antelman's commentary in 1993. This is intended to aid in paradigm selection by informing readers about rodent models, their benefits to the clinical community, challenges associated with the translational models, and opportunities for future work. To inform PTSD model validity and relevance to human psychopathology, we propose that models incorporate behavioral test batteries, individual differences, sex differences, strain and stock differences, early life stress effects, biomarkers, stringent success criteria for drug development, Research Domain Criteria, technological advances, and cross-species comparisons. We conclude that, despite the challenges, animal studies will be pivotal to advances in understanding PTSD and the neurobiology of stress.

Towards a psychobiotic therapy for depression: Bifidobacterium breve CCFM1025 reverses chronic stress-induced depressive symptoms and gut microbial abnormalities in mice

BACKGROUND

Accumulating evidence points to an association between gut microbial abnormalities and depression disorder. The microbiota-gut-brain axis is an emerging target for treating depression using nutritional strategies, considering the numerous limitations of current pharmacological approaches. Here we studied the effect and probable mechanisms of psychobiotic treatment on depression.

METHODS

Chronically stressed C57BL/6J male mice were administered viable Bifidobacterium breve CCFM1025 for 5 weeks prior to behavioral testing. Brain neurological alterations, serum corticosterone, cytokines levels, fecal microbial composition, and short-chain fatty acid (SCFA) content were measured. In addition, the effect of SCFA on 5-hydroxytryptophan (5-HTP) biosynthesis was investigated in an in vitro model of enterochromaffin cells (RIN14B).

RESULTS

CCFM1025 treatment significantly reduced depression- and anxiety-like behaviors. The hyperactive hypothalamic-pituitary-adrenal response, as well as inflammation, were also alleviated, possibly via regulating the expression of glucocorticoid receptors (Nr3c1). Moreover, CCFM1025 also down-regulated the pCREB-c-Fos pathway but increased the expression of brain-derived neurotrophic factor (BDNF). Meanwhile, chronic stress-induced gut microbial abnormalities were restored, accompanied by increased SCFA and 5-HTP levels. The intestinal 5-HTP biosynthesis positively correlated with fecal SCFA and Bifidobacterium breve levels.

CONCLUSIONS

In summary, Bifidobacterium breve CCFM1025 showed considerable antidepressant-like and microbiota-regulating effects, which opens avenues for novel therapeutic strategies towards treating depression.

Gut microbiome composition and diversity are related to human personality traits

•

Investigation of gut microbiome composition and diversity with respect to human personality.

•

Analyses targeted bacterial genera linked to behaviour in animal and human psychiatric studies.

•

Bacterial genera were modelled (using negative binomial regression) with respect to personality.

•

Genera linked to autism are also related to social behaviour in the general population.

•

Sociability is associated with higher diversity, and anxiety and stress with reduced diversity.

The gut microbiome has a measurable impact on the brain, influencing stress, anxiety, depressive symptoms and social behaviour. This microbiome–gut–brain axis may be mediated by various mechanisms including neural, immune and endocrine signalling. To date, the majority of research has been conducted in animal models, while the limited number of human studies has focused on psychiatric conditions. Here the composition and diversity of the gut microbiome is investigated with respect to human personality. Using regression models to control for possible confounding factors, the abundances of specific bacterial genera are shown to be significantly predicted by personality traits. Diversity analyses of the gut microbiome reveal that people with larger social networks tend to have a more diverse microbiome, suggesting that social interactions may shape the microbial community of the human gut. In contrast, anxiety and stress are linked to reduced diversity and an altered microbiome composition. Together, these results add a new dimension to our understanding of personality and reveal that the microbiome–gut–brain axis may also be relevant to behavioural variation in the general population as well as to cases of psychiatric disorders.

Efficacy of probiotics on cognition, and biomarkers of inflammation and oxidative stress in adults with Alzheimer's disease or mild cognitive impairment - a meta-analysis of randomized controlled trials

Probiotics are live microbes that confer health benefits to the host. Preliminary animal evidence supports the potential role of probiotics in ameliorating cognitive health, however, findings from clinical trials in Alzheimer’s disease (AD) or mild cognitive impairment (MCI) subjects are controversial. Thus, a meta-analysis is needed to clarify the efficacy of probiotics on cognition in AD or MCI patients. EMBASE, PubMed, Web of Science and Cochrane library were systematically searched and manually screened for relevant published randomized controlled trials (RCTs). Among the 890 citations identified, 5 studies involving 297 subjects met eligibility. There was a significant improvement in cognition (SMD = 0.37; 95% CI, 0.14, 0.61; P = 0.002; I² = 24%), while a significant reduction in malondialdehyde (SMD = −0.60; 95% CI, −0.91, −0.28; P = 0.000; I² = 0.0%) and high-sensitivity C-reactive protein (SMD = −0.57; 95% CI, −0.95, −0.20; P = 0.003; I² = 0.0%) post-intervention levels between the probiotics and control group. This meta-analysis indicated that probiotics improved cognitive performance in AD or MCI patients, possibly through decreasing levels of inflammatory and oxidative biomarkers. However, current evidence is insufficient, and more reliable evidence from large-scale, long-period, RCT is needed.

The Effect of Probiotic Intervention in Ameliorating the Altered Central Nervous System Functions in Neurological Disorders: A Review

There has been a significant rise in the occurrence of various neurological ailments worldwide. The need to investigate newer and safer intervention therapies with prophylactic and/or therapeutic effects is well understood. Probiotics have recently been shown to hold promise as an intervention option that warrants future work. Probiotic strains have shown beneficial treatment outcomes as evidenced in various animal and human studies. Although numerous articles have highlighted the role of gut microbiota and its cross-talk with human brain in modulating Central Nervous System (CNS) physiology and neurochemistry, the present review solely focuses on the ability of externally administered probiotic strains (that may or may not be part of the already existing gut microflora of an average human) in ameliorating the altered CNS functions in patients. The review aims at giving a comprehensive analysis of the studies performed on animals and humans and discusses the findings in different neurological and psychiatric disorders (Anxiety, Major Depressive disorder, bipolar disorder, schizophrenia, autism spectrum disorder, cognitive impairmentsetc). The article also highlights different mechanisms through which the probiotic bacteria operate in improving neurologic manifestations or decreasing the incidence of neurological disorders. These underlying mechanisms include both direct as well as indirect pathways involving neural, hormonal and immunological pathways. The potential of probiotics as an important dietary modification as well as a useful intervention therapy with preventive and therapeutic value for the target population holds strong. However, future evaluation into formulation designing, selecting the best probiotic strain(s) for each specific disease and safety and tolerability aspects in patients needs to be considered.

Immune Responses Raised in an Experimental Colon Carcinoma Model Following Oral Administration of Lactobacillus casei

The role of dietary probiotic strains on host anticancer immune responses against experimental colon carcinoma was investigated. We have previously shown that Lactobacillus casei administration led to tumor growth suppression in an experimental colon cancer model. Here, we investigated the underlying immune mechanisms involved in this tumorgrowth inhibitory effect. BALB/c mice received daily live lactobacilli per os prior to the establishment of a syngeneic subcutaneous CT26 tumor. Tumor volume, cytokine production, T cell differentiation and migration, as well as tumor cell apoptosis were examined to outline potential immunomodulatory effects following L. casei oral intake. Probiotic administration in mice resulted in a significant increase in interferon gamma (IFNγ), Granzyme B and chemokine production in the tumor tissue as well as enhanced CD8⁺ T cell infiltration, accompanied by a suppression of tumor growth. Cytotoxic activity against cancer cells was enhanced in probioticfed compared to control mice, as evidenced by the elevation of apoptotic markers, such as cleaved caspase 3 and poly (ADPribose) polymerase 1 (PARP1), in tumor tissue. Oral administration of Lactobacillus casei induced potent Th1 immune responses and cytotoxic T cell infiltration in the tumor tissue of tumorbearing mice, resulting in tumor growth inhibition. Thus, the microorganism may hold promise as a novel dietary immunoadjuvant in raising protective anticancer immune responses.

Probiotics and Maternal Mental Health: A Randomised Controlled Trial among Pregnant Women with Obesity

Poor maternal mental health has been associated with a myriad of pregnancy and child health complications. Obesity in pregnancy is known to increase one’s risk of experiencing poor maternal mental health and associated physical and mental health complications. Probiotics may represent a novel approach to intervene in poor mental health and obesity. We conducted this pre-specified secondary analysis of the Healthy Mums and Babies (HUMBA) randomised controlled trial to investigate whether probiotics would improve maternal mental health outcomes up to 36 weeks of pregnancy. Two-hundred-and-thirty pregnant women with obesity (BMI ≥ 30.0 kg/m²) were recruited and randomised to receive probiotic (Lactobacillus rhamnosus GG and Bifidobacterium lactis BB12, minimum 6.5 × 10⁹ CFU) or placebo capsules. Depression, anxiety, and functional health and well-being were assessed at baseline (12⁰−17⁶ weeks’ gestation) and 36 weeks of pregnancy. Depression scores remained stable and did not differ between the probiotic (M = 7.18, SD = 3.80) and placebo groups (M = 6.76, SD = 4.65) at 36 weeks (p-values > 0.05). Anxiety and physical well-being scores worsened over time irrespective of group allocation, and mental well-being scores did not differ between the two groups at 36 weeks. Probiotics did not improve mental health outcomes in this multi-ethnic cohort of pregnant women with obesity.

Antidepressive Mechanisms of Probiotics and Their Therapeutic Potential

The accumulating knowledge of the host-microbiota interplay gives rise to the microbiota-gut-brain (MGB) axis. The MGB axis depicts the interkingdom communication between the gut microbiota and the brain. This communication process involves the endocrine, immune and neurotransmitters systems. Dysfunction of these systems, along with the presence of gut dysbiosis, have been detected among clinically depressed patients. This implicates the involvement of a maladaptive MGB axis in the pathophysiology of depression. Depression refers to symptoms that characterize major depressive disorder (MDD), a mood disorder with a disease burden that rivals that of heart diseases. The use of probiotics to treat depression has gained attention in recent years, as evidenced by increasing numbers of animal and human studies that have supported the antidepressive efficacy of probiotics. Physiological changes observed in these studies allow for the elucidation of probiotics antidepressive mechanisms, which ultimately aim to restore proper functioning of the MGB axis. However, the understanding of mechanisms does not yet complete the endeavor in applying probiotics to treat MDD. Other challenges remain which include the heterogeneous nature of both the gut microbiota composition and depressive symptoms in the clinical setting. Nevertheless, probiotics offer some advantages over standard pharmaceutical antidepressants, in terms of residual symptoms, side effects and stigma involved. This review outlines antidepressive mechanisms of probiotics based on the currently available literature and discusses therapeutic potentials of probiotics for depression.

Which Symptoms, Complaints and Complications of the Gastrointestinal Tract Occur in Patients With Eating Disorders? A Systematic Review and Quantitative Analysis

BACKGROUND

Eating disorders (ED) such as anorexia nervosa (AN), bulimia nervosa (BN), and binge eating disorder (BED) are often accompanied by a variety of psychological and physical comorbidities. Gastrointestinal (GI) symptoms are a classical feature in most patients with ED. The heterogeneity of studies on this topic is high, making it difficult to have a clear overview. The aim of this systematic review is therefore to provide an overview of subjectively and objectively measured differences and changes in the GI tract in patients with EDs, along with the occurrence of GI complications.

METHODS

A systematic literature search was conducted in PubMed, Web of Science, and Google Scholar to find all relevant studies examining GI problems in AN, BN, and BED. Quantitative analyses were performed for objective GI physiology measures where applicable.

RESULTS

The review differentiated between ED types and also between studies that report GI outcomes of ED in (i) human studies with an ED diagnosis excluding case reports that provide an overview of GI problems in ED and (ii) case reports with an ED diagnosis describing rare GI complications in ED. GI symptoms and impaired gastric transit times were frequent features of EDs with specific differences found for the ED types. During the time course of treatment, GI symptoms changed and/or improved but not completely. GI complications extended the range of GI problems observed, including a variety of serious complications such as gastric dilatation.

CONCLUSIONS

Problems of the GI tract are frequent in patients with ED and it is likely that they complicate therapy, especially in patients with AN.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO registration number: CRD42019100585.

Properties of recombinant 4-α-glucanotransferase from Bifidobacterium longum subsp. longum JCM 1217 and its application

To determine the physiochemical properties of the 4-α-glucanotransferase from Bifidobacterium sp., the bllj_0114 gene encoding 4-α-glucanotransferase was cloned from Bifidobacterium longum subsp. longum JCM 1217 and expressed in Escherichia coli. The amino acid sequence alignment indicated that the recombinant protein, named BL-αGTase, belongs to the glycoside hydrolase (GH) family 77. BL-αGTase was purified using nickel-nitrilotriacetic acid affinity chromatography and characterized using various substrates. The enzyme catalyzed the disproportionation activity, which transfers a glucosyl unit from oligosaccharides to acceptor molecules, and had the highest activity at 40 °C and pH 6.0. In the presence of 5 mM metal ions, in particular Cu²⁺, Zn²⁺, and Fe²⁺, BL-αGTase activity was reduced. To determine whether BL-αGTase can be used to generate thermoreversible gels, potato starch was treated with BL-αGTase for various reaction times. The BL-αGTase-treated starches showed sol-gel reversibility and melted at 59.6-75.7 °C.

Eating Disorders and Gastrointestinal Diseases

Eating disorders (ED) are frequently associated with a wide range of psychiatric or somatic comorbidities. The most relevant ED are anorexia nervosa (AN), bulimia nervosa (BN), and binge eating disorders (BED). Patients with ED exhibit both upper and lower gastrointestinal (GI) symptoms. Evidence of alterations throughout the GI tract in ED will be analyzed given the role of the GI tract in food intake and its regulation. It remains a matter of debate whether GI disorders are inherent manifestations of ED or the results of malnutrition occurring from ED. Moreover, recent clinical studies have highlighted the growing role of intestinal microbiota in the pathogenesis of ED, making it possible to hypothesize a modulation of intestinal microbiota as a co-adjuvant to standard therapy. The aim of this review is to analyze the link between ED and GI diseases and to present, where known, the potential key factors underlying these conditions. Conclusions: The presence of GI disorders should be investigated in patients with ED. Screening for ED should also be encouraged in individuals seeking treatment for unexplained GI complaints to better address therapeutic issues that surround these difficult medical conditions.

Eating Disorders and Gastrointestinal Diseases

Eating disorders (ED) are frequently associated with a wide range of psychiatric or somatic comorbidities. The most relevant ED are anorexia nervosa (AN), bulimia nervosa (BN), and binge eating disorders (BED). Patients with ED exhibit both upper and lower gastrointestinal (GI) symptoms. Evidence of alterations throughout the GI tract in ED will be analyzed given the role of the GI tract in food intake and its regulation. It remains a matter of debate whether GI disorders are inherent manifestations of ED or the results of malnutrition occurring from ED. Moreover, recent clinical studies have highlighted the growing role of intestinal microbiota in the pathogenesis of ED, making it possible to hypothesize a modulation of intestinal microbiota as a co-adjuvant to standard therapy. The aim of this review is to analyze the link between ED and GI diseases and to present, where known, the potential key factors underlying these conditions. Conclusions: The presence of GI disorders should be investigated in patients with ED. Screening for ED should also be encouraged in individuals seeking treatment for unexplained GI complaints to better address therapeutic issues that surround these difficult medical conditions.

Oral microbiota and autism spectrum disorder (ASD)

Autism spectrum disorder (ASD) is associated with several oropharyngeal abnormalities, including dysbiosis in the oral microbiota. Since the oral cavity is the start of the gastrointestinal tract, this strengthens and extends the notion of a microbial gut-brain axis in ASD and even raises the question whether a microbial oral-brain axis exists. It is clear that oral bacteria can find their way to the brain through a number of pathways following routine dental procedures. A connection between the oral microbiota and a number of other brain disorders has been reported. As the evidence so far for an association between the oral microbiota and ASDs rests on a few reports only, further studies in this field are necessary. The current review discusses a possible relationship between oral bacteria and the biologic and symptomologic aspects of ASD, focusing on the clinical implications for diagnostic and therapeutic development.

Effect of probiotic supplementation on cognitive function in children and adolescents: a systematic review of randomised trials

Available reviews have shown potential effects of probiotics on neurobehavioral outcomes through ‘gut-brain axis’ mechanism in adults. However, reviews on cognitive function in children and adolescents are lacking. Therefore, we conducted a systematic review of randomised controlled trials (RCTs) of the effect of probiotic supplementation on cognitive function in children and adolescents. A search of four databases (Cochrane Central Register of Controlled Trials, PsycARTICLES, Scopus, PubMed) was conducted to identify RCTs published from January 1990 to December 2018. Seven studies met the inclusion criteria and their cognitive outcomes were analysed. Only one study found a positive result with Lactobacillus rhamnosus GG (LGG) 1×1010 cfu supplementation with outcomes on attention deficit hyperactivity disorder (ADHD) or Asperger syndrome (AS) manifestations as diagnosed using the International Classification of Diseases-10 criteria. The supplementations were administered to Finnish mothers for 4 weeks before delivery and continuously given for 6 months after delivery if they breastfed, or to the children. ADHD or AS was diagnosed at the age of 13 years in 17.1% children in the placebo and none in the probiotic group (P=0.008). This study found significant differences in species composition and number of cells belonging to the genus Bifidobacterium between healthy children and children who later developed ADHD or AS at different time points. Six remaining studies with varying strains, durations of intervention, start-time of administration, and outcomes demonstrated no difference in cognition after probiotic supplementation. Metagenomic analyses on gut microbiota composition were not performed in any of these studies. In conclusion, the favourable effect of probiotic supplementation on cognitive function in children and adolescents was observed in one study with LGG supplementation by a risk reduction of developing ADHD or AS (i.e. autism). More long-term and follow-up trials using probiotics identifying the effect on cognition are warranted before routine use.

Strain specific stress-modulating effects of candidate probiotics: A systematic screening in a mouse model of chronic restraint stress

BACKGROUND

Changes in the gut microbiota have been implicated in mood and cognition. In rodents, supplementation with certain bacteria have been shown to alleviate adverse effects of stress on gut microbiota composition and behaviour, but little is known of how the performance of different strains compare to each other. We took a systematic approach to test the efficacy of twelve candidate probiotic strains from ten species/sub-species of Bifidobacterium and Lactobacillus on behaviours and neuroendocrine responses of chronically stressed mice.

METHODS

The strains were tested in four screening experiments with non-stressed and chronically stressed vehicle groups. The three most efficacious strains were re-tested to validate the results. Mice were administered a daily oral gavage containing either 1 × 10⁹ colony forming units (CFU) of selected candidate probiotic or saline solution for one week prior to and for three weeks during daily chronic restraint stress. Behavioural tests including the elevated plus maze, open field, novel object recognition, and forced swim test were applied during week five. Corticosterone and adrenocorticotropic hormone (ACTH) were analysed to measure the neuroendocrine response to stress. Plasma and tissue samples were collected for biomarker analyses.

RESULTS

Of the twelve candidate probiotics, Lactobacillus paracasei Lpc-37, Lactobacillus plantarum LP12407, Lactobacillus plantarum LP12418 and Lactobacillus plantarum LP12151 prevented stress-associated anxiety and depression-related behaviours from developing compared with chronically stressed vehicle mice. In addition, Lpc-37 improved cognition.

CONCLUSION

This systematic screening indicates species- and strain-dependent effects on behavioural outcomes related to stress and further suggests that strains differ from each other in their effects on potential mechanistic outcomes.

Intergenerational Transmission of Characters Through Genetics, Epigenetics, Microbiota, and Learning in Livestock

Evolutionary biologists studying wild species have demonstrated that genetic and non-genetic sources of information are inherited across generations and are therefore responsible for phenotypic resemblance between relatives. Although it has been postulated that non-genetic sources of inheritance are important in natural selection, they are not taken into account for livestock selection that is based on genetic inheritance only. According to the natural selection theory, the contribution of non-genetic inheritance may be significant for the transmission of characters. If this theory is confirmed in livestock, not considering non-genetic means of transmission in selection schemes might prevent achieving maximum progress in the livestock populations being selected. The present discussion paper reviews the different mechanisms of genetic and non-genetic inheritance reported in the literature as occurring in livestock species. Non-genetic sources of inheritance comprise information transmitted via physical means, such as epigenetic and microbiota inheritance, and those transmitted via learning mechanisms: behavioral, cultural and ecological inheritance. In the first part of this paper we review the evidence that suggests that both genetic and non-genetic information contribute to inheritance in livestock (i.e. transmitted from one generation to the next and causing phenotypic differences between individuals) and discuss how the environment may influence non-genetic inherited factors. Then, in a second step, we consider methods for favoring the transmission of non-genetic inherited factors by estimating and selecting animals on their extended transmissible value and/or introducing favorable non-genetic factors via the animals’ environment.

Effects of a probiotic treatment (Enterococcus faecalis) and open-label placebo on symptoms of allergic rhinitis: study protocol for a randomised controlled trial

INTRODUCTION

Several studies suggest that gut microbiota may play an important role in allergic diseases. The present trial aims to examine effects of the probiotic Enterococcus faecalis on symptoms of allergic rhinitis in patients. Effects of this probiotic on the immune system have been reported by several studies, but the majority of the previous trials were animal studies. In addition, it is well known that symptoms in allergic rhinitis are prone to exhibit high placebo responses. Moreover, recent studies report that even placebos without deception (open-label placebos) are highly effective in reducing symptoms of allergic rhinitis. Our study design combines both new approaches to assess effects on allergic symptoms in patients. The objective of this study is to compare the effects of a probiotic treatment (E. faecalis) with effects seen by open-label placebo, concealed placebo treatment and no treatment control.

METHODS AND ANALYSIS

A total of 120 patients with allergic rhinitis will be randomly assigned to one of four different groups: a double-blind probiotic/placebo group (groups 1 and 2), an open-label placebo group (group 3) and a no-treatment group (group 4) to control for spontaneous variation of symptoms. The primary outcome is the evaluation of allergic symptoms using the Combined Symptoms Medication Score. Furthermore, health-related quality of life is examined (Rhinitis Quality of Life Questionnaire). Secondary outcomes include a visual analogue scale on allergic burden and a second quality of life questionnaire. This report describes the study design of the randomised controlled trial.

ETHICS AND DISSEMINATION

The study design was approved by the ethical committee of the UKT Department of Psychosomatic Medicine and Psychotherapy, Tübingen, Germany. The trial is registered at the German Clinical Trials Register (www.drks.de, DRKS00015804). The trial results will be published in peer-reviewed journals and at conferences.

TRIAL REGISTRATION NUMBER

German Clinical Trials Register (www.drks.de, DRKS00015804); Pre-results.