Probiotic supplementation and systemic inflammation in relapsing-remitting multiple sclerosis: A randomized, double-blind, placebo-controlled trial

The potential effectiveness of probiotics in reducing multiple sclerosis progression in preclinical and clinical studies: A worldwide systematic review and meta-analysis

BACKGROUND AND OBJECTIVE

Multiple Sclerosis (MS) is an immune-mediated disease characterized by nerve cell inflammation and demyelination. The effectiveness of probiotics in reducing inflammatory damage in MS. Therefore, the aim of this systematic review and meta-analysis was the potential effectiveness of probiotics in reducing Multiple Sclerosis progression in preclinical and clinical studies.

METHODS

PubMed, Scopus, Cochrane, and Google Scholar databases were searched using multiple relevant keywords, and screening was carried out based on the inclusion/exclusion criteria from January 2004 to August 16, 2024.

RESULTS

Based on our criteria, 269 papers were obtained, and after omission of unsuitable articles, 23 full-text articles consisting of 17 animal studies and six human models were selected. It was concluded that in an experimental autoimmune encephalomyelitis (EAE) animal model, probiotics such as Bifidobacterium, Prevotella, and Lactobacillus can decrease the T helper 1 (Th1)/Th17 ratio while inducing interferon gamma (IFN-γ) and interleukin (IL)-17 levels. In all cases, probiotics can modulate immune cells and cytokines and consequently decrease EAE signs and symptoms. In all human studies, single or multiple probiotics decreased the severity of disease and changed the gut microbiota population.

CONCLUSION

Our results showed that probiotics can control the development of MS by reducing inflammatory conditions, and may have beneficial effects in the prevention and treatment of MS.

Effect of probiotics on cognitive function and cardiovascular risk factors in mild cognitive impairment and Alzheimer's disease: an umbrella meta-analysis

BACKGROUND

This umbrella meta-analysis evaluates the effects of probiotics on cognitive function and metabolic health in Alzheimer's disease (AD) and mild cognitive impairment (MCI) by synthesizing findings from meta-analyses of randomized controlled trials (RCTs), as existing evidence remains inconclusive.

METHODS

A systematic search was conducted in PubMed, Web of Science, and Scopus to identify meta-analyses of RCTs investigating the impact of probiotic supplementation on cognitive function and metabolic biomarkers. The random-effects model was used. Heterogeneity and publication bias were assessed.

RESULTS

Thirteen meta-analyses, comprising 3910 patients, were included. Probiotics significantly improved cognitive function in AD (SMD = 0.78, 95% CI: 0.33 to 1.23) and MCI (SMD = 0.43, 95% CI: 0.15 to 0.70). Probiotics also increased total antioxidant capacity (SMD = 0.40, 95% CI: 0.11 to 0.70) and reduced MDA (SMD =  - 0.35, 95% CI: - 0.62 to - 0.09) and hs-CRP (SMD =  - 0.59, 95% CI: - 0.87 to - 0.30). Insulin resistance improved, as reflected by decreased HOMA-IR (SMD =  - 0.34, 95% CI: - 0.43 to - 0.26). No significant effects were observed on glutathione, nitric oxide, or lipid profiles.

CONCLUSION

Probiotic supplementation appears to enhance cognitive function and metabolic parameters in individuals with MCI and AD, likely through mechanisms involving inflammation reduction, oxidative stress modulation, and improved insulin sensitivity. Further high-quality RCTs are required to validate these findings and determine optimal probiotic formulations.

Probiotics as Potential Treatments for Neurodegenerative Diseases: a Review of the Evidence from in vivo to Clinical Trial

Neurodegenerative diseases (NDDs), characterized by the progressive deterioration of the structure and function of the nervous system, represent a significant global health challenge. Emerging research suggests that the gut microbiota plays a critical role in regulating neurodegeneration via modulation of the gut-brain axis. Probiotics, defined as live microorganisms that confer health benefits to the host, have garnered significant attention owing to their therapeutic potential in NDDs. This review examines the current research trends related to the microbiome-gut-brain axis across various NDDs, highlighting key findings and their implications. Additionally, the effects of specific probiotic strains, including Lactobacillus plantarum, Bifidobacterium breve, and Lactobacillus rhamnosus, on neurodegenerative processes were assessed, focusing on their potential therapeutic benefits. Overall, this review emphasizes the potential of probiotics as promising therapeutic agents for NDDs, underscoring the importance of further investigation into this emerging field.

Pyroptosis the Emerging Link Between Gut Microbiota and Multiple Sclerosis

This review elucidates the pivotal role of pyroptosis, triggered by gut microbiota, in the development of multiple sclerosis (MS), emphasizing its significance within the gut-brain axis. Our comprehensive analysis of recent literature reveals how dysbiosis in the gut microbiota of MS patients-characterized by reduced microbial diversity and shifts in bacterial populations-profoundly impacts immune regulation and the integrity of the central nervous system (CNS). Pyroptosis, an inflammatory form of programmed cell death, significantly exacerbates MS by promoting the release of inflammatory cytokines and causing substantial damage to CNS tissues. The gut microbiota facilitates this detrimental process through metabolites such as short-chain fatty acids and neuroactive compounds, or self-structural products like lipopolysaccharides (LPS), which modulate immune responses and influence neuronal survival. This review highlights the potential of modulating gut microbiota to regulate pyroptosis, thereby suggesting that targeting this pathway could be a promising therapeutic strategy to mitigate inflammatory responses and preserve neuronal integrity in patients with MS.

Effects of Probiotics on Neurodegenerative Disease-Related Symptoms and Systemic Inflammation: A Systematic Review

In recent years, probiotics, as a class of biologically active microorganisms, have increasingly attracted attention for their potential in treating neurodegenerative diseases (NDDs). To comprehensively assess the effects of probiotics on clinical symptoms and systemic inflammation regulation in various NDDs, this systematic review conducted a detailed search of the Cochrane Library, Embase, PubMed, and Web of Science databases, ultimately including 22 eligible randomized controlled trials (RCTs), with 4 RCTs for Alzheimer's Disease (AD), 10 RCTs for Parkinson's Disease (PD), 2 RCTs for Multiple Sclerosis (MS), and 2 RCTs for Mild Cognitive Impairment (MCI), and intervention durations ranging from 4 to 16 weeks. The comprehensive analysis indicates that probiotics help improve clinical symptoms related to NDDs, including gastrointestinal function, cognitive function, quality of life, and mental health. Additionally, probiotics generally have a positive effect on reducing systemic inflammation and enhancing antioxidant capacity in patients. In conclusion, existing evidence supports the promising potential of probiotics in treating NDDs. However, further large-scale, high-quality studies are needed to explore specific differences in efficacy among various probiotic strains, dosages, and modes of administration. Moreover, considering that lifestyle and dietary habits may modulate the effects of probiotics, these external factors should also be included in research considerations to gain a more comprehensive understanding of the mechanisms and application strategies of probiotics in NDDs treatment.

The effect of probiotic, prebiotic, and synbiotic supplements on anthropometric measures and respiratory infections in malnourished children: a systematic review and meta-analysis of randomized controlled trials

BACKGROUND

Malnutrition remains a significant concern in many societies. This study systematically reviewed the effects of probiotics, prebiotics, and synbiotics on anthropometric measures in malnourished children, focusing on changes in weight, height, and respiratory infections (primary outcomes), and head circumference, hemoglobin, hematocrit, and body mass index (BMI) as secondary outcomes.

METHODS

This systematic review and meta-analysis involved searching various databases in both Persian and English, including Scopus, Web of Science Core Collection, Cochrane Library, Science Direct, and PubMed up to October 5, 2024. Non-randomized controlled trials (RCTs) were excluded. The Cochrane Handbook Risk of Bias Version 2 tool was used to assess risk of bias, and RevMan 5.3 software was employed for analysis. Subgroup analyses were conducted based on the type of supplement received. Meta-regression was applied to identify factors influencing results, and the GRADE approach was used to evaluate evidence certainty.

RESULTS

Twelve studies with a total of 3,086 children (aged up to 6 years, equally distributed between boys and girls) were included. All children were malnourished without underlying illnesses. Limitations of the study included variations in intervention type, dose, duration, and timing of outcome measurement. Meta-analysis revealed that probiotics, prebiotics, and synbiotics may increase weight (6 trials, mean difference: 0.33 kg, 95% CI: 0.15 to 0.50, low certainty of evidence), while probiotics and synbiotics may increase height compared to control groups (5 trials, mean difference: 0.44 cm, 95% CI: 0.02 to 0.85, low certainty of evidence). However, probiotics and synbiotics did not show a statistically significant effect on lower respiratory tract infections (5 trials, risk ratio: 0.84, 95% CI: 0.68 to 1.04, moderate certainty of evidence). Meta-regression indicated that intervention type, sample size, and follow-up duration were not significant moderators for outcomes related to weight, height, or respiratory infections.

CONCLUSION

The current evidence suggests that probiotics, prebiotics, and synbiotics supplements may help manage malnutrition-related outcomes in malnourished children, but further research with stronger study designs is needed to confirm these findings due to the low certainty of evidence.

The influence of aging and the microbiome in multiple sclerosis and other neurologic diseases

The human gut microbiome is well-recognized as a key player in maintaining health. However, it is a dynamic entity that changes across the lifespan. How the microbial changes that occur in later decades of life shape host health or impact age-associated inflammatory neurological diseases such as multiple sclerosis (MS) is still unclear. Current understanding of the aging gut microbiome is largely limited to cross-sectional observational studies. Moreover, studies in humans are limited by confounding host-intrinsic and extrinsic factors that are not easily disentangled from aging. This review provides a comprehensive summary of existing literature on the aging gut microbiome and its known relationships with neurological diseases, with a specific focus on MS. We will also discuss preclinical animal models and human studies that shed light on the complex microbiota-host interactions that have the potential to influence disease pathology and progression in aging individuals. Lastly, we propose potential avenues of investigation to deconvolute features of an aging microbiota that contribute to disease, or alternatively promote health in advanced age.

Nutritional interventional studies in patients with multiple sclerosis: a scoping review of the current clinical evidence

A good nutritional status appears to slow down disease progression and ameliorate symptoms' intensity in patients with multiple sclerosis (MS). Up to date, there are several interventional studies, which have explored the potential beneficial effects of specific dietary patterns as well as specific bioactive nutrients against disease progression and symptomatology of MS patients. This is a thorough, scoping review, which aims to critically summarize and scrutinize the currently available clinical evidence of the potential beneficial effects of nutritional interventional studies against MS progression and symptomatology. This review was conducted to systematically map the research done in this area, as well as to identify gaps in knowledge. For this purpose, we thoroughly explored the most accurate scientific web databases, e.g., PubMed, Scopus, Web of Science, and Google Scholar to achieve the most relevant clinical human studies applying effective and characteristic keywords. There are currently several dietary patterns and specific bioactive nutrients that show promising results by slowing down disease progression and by improving MS symptoms. However, there are also certain conflicting results, while most of the existing studies enrolled a small number of MS patients. Nutritional interventions may exert substantial protective effects against MS progression and symptomatology. However, large, long-term, randomized, double-blind, controlled clinical trials with a prospective design are strongly recommended to delineate whether such nutritional intervention may attenuate disease progression, and improve symptomatology in MS patients.

Predispose, precipitate, perpetuate, and protect: how diet and the gut influence mental health in emerging adulthood

Medicine often employs the 4Ps of predisposing, precipitating, perpetuating, and protective factors to identify salient influences on illness states, and to help guide patient care. Mental illness is a significant cause of morbidity and mortality worldwide. Mental health is a complex combination of biological, psychological, environmental, and social factors. There is growing interest in the gut-brain-microbiome (GBM) axis and its impact on mental health. We use the medical model of the 4Ps to explore factors involving the connection between nutrition and the GBM axis and their associated risks with mental health problems in emerging adults (EAs), a life stage when mental illness onset is the most common. We review the impact of current dietary trends on the GBM and on mental health, and the role that gut microbiome-based interventions can have in modulating the GBM axis of EAs. We discuss the implications of gut health on the GBM and areas for clinical intervention.

Comparison of the efficacy of fish oil and probiotic supplementation on glucose and lipid metabolism in patients with type 2 diabetes: a systematic review and network meta-analysis

BACKGROUND

Abnormalities in glucose and lipid metabolism contribute to the progression and exacerbation of type 2 diabetes mellitus (T2DM). Fish oil and probiotics are dietary supplements that have the potential to improve glucose and lipid metabolism. However, their efficacy remains unclear in T2DM patients.

METHODS

PubMed, Embase, and the Cochrane Library were retrieved to collect randomized controlled trials (RCTs) on the efficacy of fish oil or probiotic supplementation in T2DM patients from the database inception to December 13, 2023. Primary outcome indicators encompassed glycated hemoglobin (HbA1c), homeostatic model assessment for insulin resistance (HOMA-IR) and blood lipid profile (triglyceride (TG) and total cholesterol (TC). Secondary outcome indicators included inflammatory markers such as tumor necrosis factor -α (TNF-α) and adipocytokine (including leptin and adiponectin). The R software was used for statistical analysis, and GraphPad Prism was used for figure rendering.

RESULTS

A total of 60 RCTs involving 3845 T2DM patients were included in the analysis. The results showed that the probiotics (Bifidobacterium, Lactobacillus, Lactococcus, Propionibacterium, etc.) were more effective in reducing HOMA-IR than fish oil (Surca = 0.935). Bifidobacterium demonstrated the highest efficacy in reducing HbA1c levels (Surca = 0.963). Regarding lipid metabolism, fish oil was superior to probiotics in lowering TG and TC levels (Surca values of 0.978 and 0.902, respectively). Furthermore, fish oil outperformed probiotics in reducing TNF-α (Surca = 0.839) and leptin (Surca = 0.712), and increasing adiponectin levels (Surca = 0.742). Node-splitting analysis showed good consistency (P > 0.05 for direct, indirect, and network comparison across various interventions).

CONCLUSIONS

In T2DM patients, fish oil was more effective than probiotics in regulating lipid metabolism. Probiotics outperformed fish oil in regulating glucose metabolism particularly; specifically, Bifidobacterium showed higher efficacy in reducing blood glucose.

The Gut-Brain Axis as a Therapeutic Target in Multiple Sclerosis

The CNS is very susceptible to oxidative stress; the gut microbiota plays an important role as a trigger of oxidative damage that promotes mitochondrial dysfunction, neuroinflammation, and neurodegeneration. In the current review, we discuss recent findings on oxidative-stress-related inflammation mediated by the gut-brain axis in multiple sclerosis (MS). Growing evidence suggests targeting gut microbiota can be a promising strategy for MS management. Intricate interaction between multiple factors leads to increased intra- and inter-individual heterogeneity, frequently painting a different picture in vivo from that obtained under controlled conditions. Following an evidence-based approach, all proposed interventions should be validated in clinical trials with cohorts large enough to reach significance. Our review summarizes existing clinical trials focused on identifying suitable interventions, the suitable combinations, and appropriate timings to target microbiota-related oxidative stress. Most studies assessed relapsing-remitting MS (RRMS); only a few studies with very limited cohorts were carried out in other MS stages (e.g., secondary progressive MS-SPMS). Future trials must consider an extended time frame, perhaps starting with the perinatal period and lasting until the young adult period, aiming to capture as many complex intersystem interactions as possible.

The brain-gut-microbiota axis in the treatment of neurologic and psychiatric disorders

The human gut microbiota is a complex ecosystem made of trillions of microorganisms. The composition can be affected by diet, metabolism, age, geography, stress, seasons, temperature, sleep, and medications. The increasing evidence about the existence of a close and bi-directional correlation between the gut microbiota and the brain indicates that intestinal imbalance may play a vital role in the development, function, and disorders of the central nervous system. The mechanisms of interaction between the gut-microbiota on neuronal activity are widely discussed. Several potential pathways are involved with the brain-gut-microbiota axis, including the vagus nerve, endocrine, immune, and biochemical pathways. Gut dysbiosis has been linked to neurological disorders in different ways that involve activation of the hypothalamic-pituitary-adrenal axis, imbalance in neurotransmitter release, systemic inflammation, and increase in the permeability of the intestinal and the blood-brain barrier. Mental and neurological diseases have become more prevalent during the coronavirus disease 2019pandemic and are an essential issue in public health globally. Understanding the importance of diagnosing, preventing, and treating dysbiosis is critical because gut microbial imbalance is a significant risk factor for these disorders. This review summarizes evidence demonstrating the influence of gut dysbiosis on mental and neurological disorders.

Sjögren's Syndrome Treatments in the Microbiome Era

Sjögren's syndrome (SS) is a chronic autoimmune disease characterized by inflammatory cell infiltration of the salivary and lacrimal glands, resulting in acinar epithelial cell atrophy, cell death, and loss of exocrine function. At least half of SS patients develop extraglandular inflammatory disease and have a wide range of systemic clinical manifestations that can affect any organ system, including connective tissues. As many as 3.1 million people in the U.S. suffer from SS, a disease that causes severe impairment. Women are nine times more likely than men to be affected by this condition. Unfortunately, there is currently no effective treatment for SS, and the available options only provide partial relief. Treatment involves using replacement therapies such as artificial saliva and eye lubricants, or immunosuppressive agents that have limited efficacy. The medical community recognizes that there is a significant need for more effective treatments for SS. Increasing evidence demonstrates the links between the dysfunction of the human microbial community and the onset and development of many human diseases, signifying the potential use of microorganisms as an alternative strategy to conquer these issues. The role of the microbiome in controlling immune function of the human host in the context of autoimmune diseases like SS is now becoming better understood and may help to enable new drug development strategies. Natural probiotics and synthetic biology applications hold promise for novel treatment approaches to solve the encryption of many complex and multifactorial immune disorders, like SS.