Effectiveness of Multistrain Probiotic Formulation on Common Infectious Disease Symptoms and Gut Microbiota Modulation in Flu-Vaccinated Healthy Elderly Subjects

The Immunomodulatory Effects and Applications of Probiotic Lactiplantibacillus plantarum in Vaccine Development

Lactiplantibacillus plantarum (previously known as Lactobacillus plantarum) is a lactic acid bacterium that exists in various niches. L. plantarum is a food-grade microorganism that is commonly considered a safe and beneficial microorganism. It is widely used in food fermentation, agricultural enhancement, and environmental protection. L. plantarum is also part of the normal flora that can regulate the intestinal microflora and promote intestinal health. Some strains of L. plantarum are powerful probiotics that induce and modulate the innate and adaptive immune responses. Due to its outstanding immunoregulatory capacities, an increasing number of studies have examined the use of probiotic L. plantarum strains as natural immune adjuvants or alternative live vaccine carriers. The present review summarizes the main immunomodulatory characteristics of L. plantarum and discusses the preliminary immunological effects of L. plantarum as a vaccine adjuvant and delivery carrier. Different methods for improving the immune capacities of recombinant vector vaccines are also discussed.

A Narrative Review on Gut Microbiome Disturbances and Microbial Preparations in Myalgic Encephalomyelitis/Chronic Fatigue Syndrome: Implications for Long COVID

Myalgic encephalomyelitis, also known as chronic fatigue syndrome (ME/CFS), and long COVID are complex, multisystemic and long-term disabling conditions characterized by debilitating post-exertional malaise and other core symptoms related to immune dysregulation resultant from post-viral infection, including mitochondrial dysfunction, chronic neuroinflammation and gut dysbiosis. The reported associations between altered microbiota composition and cardinal symptoms of ME/CFS and long COVID suggest that the use of microbial preparations, such as probiotics, by restoring the homeostasis of the brain-immune-gut axis, may help in the management of symptoms in both conditions. Therefore, this review aims to investigate the implications of alerted gut microbiome and assess the evidence supporting use of microbial-based preparations, including probiotics, synbiotics, postbiotics alone and/or in combination with other nutraceuticals in the management of fatigue, inflammation and neuropsychiatric and gastrointestinal symptoms among patients with ME/CFS and long COVID.

The effect of oral probiotics on response to vaccination in older adults: a systematic review of randomised controlled trials

This systematic review evaluated the impact of oral probiotics on the immune response to vaccination in older people. A literature search was performed in three electronic databases up to January 2023. Randomised controlled trials (RCTs) conducted in older people (age ≥ 60 years) investigating oral probiotics and vaccine response outcomes were included. Characteristics and outcome data of the included studies were extracted and analysed and study quality was assessed using the Cochrane Risk of Bias Tool for randomised trials. Ten RCTs involving 1,560 participants, reported in 9 papers, were included. Nine studies involved the seasonal influenza vaccine and one a COVID-19 vaccine. All studies used lactobacilli, some in combination with bifidobacteria. Studies reported outcomes including anti-vaccine antibody titres or concentrations, seroconversion and seroprotection. When comparing antibody titres, seroprotection rate and seroconversion rate between probiotic and placebo groups expressed as a response ratio, the weighted mean values were 1.29, 1.16 and 2.00, respectively. Meta-analysis showed that probiotics increase seroconversion rates to all three strains of the seasonal influenza vaccine: odds ratio (95% confidence interval) 2.74 (1.31, 5.70; P = 0.007) for the H1N1 strain; 1.90 (1.04, 3.44; P = 0.04) for the H3N2 strain; 1.72 (1.05, 2.80; P = 0.03) for the B strain. There was a low level of heterogeneity in these findings. Several studies were at high risk of bias due to missing outcome data. Lactobacilli may improve the vaccine response, but further research is needed to be more certain of this.

Human trials exploring anti-aging medicines

Here, we summarize the current knowledge on eight promising drugs and natural compounds that have been tested in the clinic: metformin, NAD+ precursors, glucagon-like peptide-1 receptor agonists, TORC1 inhibitors, spermidine, senolytics, probiotics, and anti-inflammatories. Multiple clinical trials have commenced to evaluate the efficacy of such agents against age-associated diseases including diabetes, cardiovascular disease, cancer, and neurodegenerative diseases. There are reasonable expectations that drugs able to decelerate or reverse aging processes will also exert broad disease-preventing or -attenuating effects. Hence, the outcome of past, ongoing, and future disease-specific trials may pave the way to the development of new anti-aging medicines. Drugs approved for specific disease indications may subsequently be repurposed for the treatment of organism-wide aging consequences.

Gut microbiome in healthy aging versus those associated with frailty

As the proportion of older people in the world's population steadily increases, there is an urgent need to identify ways to support healthy aging. The gut microbiome has been proposed to be involved in aging-related diseases and has become an attractive target for improving health in older people. Herein, we cover the relationship between the gut microbiome and chronological age in adults, and then, we discuss the gut microbiome features associated with frailty, as a hallmark of unhealthy aging in older people. Furthermore, we describe the effects of microbiome-targeted interventions, such as dietary patterns and consumption of probiotics, prebiotics, and synbiotics, on modulating the gut microbiome composition and further promoting healthy aging. Further studies are needed to explore the underlying mechanisms of gut microbiome-induced aging complications and to develop personalized microbiome-based strategies for reducing the severity of frailty or preventing the onset of frailty in older adults.

Recent five-year progress in the impact of gut microbiota on vaccination and possible mechanisms

Vaccine is the most effective way to prevent the spread of communicable diseases, but the immune response induced by it varies greatly between individuals and populations in different regions of the world. Current studies have identified the composition and function of the gut microbiota as key factors in modulating the immune response to vaccination. This article mainly reviews the differences in gut microbiota among different groups of vaccinated people and animals, explores the possible mechanism of vaccine immunity affected by gut microbiota, and reviews the strategies for targeting gut microbiota to improve vaccine efficacy.

Impact of aging on immunity in the context of COVID-19, HIV, and tuberculosis

Knowledge of aging biology needs to be expanded due to the continuously growing number of elderly people worldwide. Aging induces changes that affect all systems of the body. The risk of cardiovascular disease and cancer increases with age. In particular, the age-induced adaptation of the immune system causes a greater susceptibility to infections and contributes to the inability to control pathogen growth and immune-mediated tissue damage. Since the impact of aging on immune function, is still to be fully elucidated, this review addresses some of the recent understanding of age-related changes affecting key components of immunity. The emphasis is on immunosenescence and inflammaging that are impacted by common infectious diseases that are characterized by a high mortality, and includes COVID-19, HIV and tuberculosis.

Association between Gut Microbiota and SARS-CoV-2 Infection and Vaccine Immunogenicity

Gut microbiota is increasingly recognized to play a pivotal role in various human physiological functions and diseases. Amidst the COVID-19 pandemic, research has suggested that dysbiosis of the gut microbiota is also involved in the development and severity of COVID-19 symptoms by regulating SARS-CoV-2 entry and modulating inflammation. Previous studies have also suggested that gut microbiota and their metabolites could have immunomodulatory effects on vaccine immunogenicity, including influenza vaccines and oral rotavirus vaccines. In light of these observations, it is possible that gut microbiota plays a role in influencing the immune responses to COVID-19 vaccinations via similar mechanisms including effects of lipopolysaccharides, flagellin, peptidoglycan, and short-chain fatty acids. In this review, we give an overview of the current understanding on the role of the gut microbiota in COVID-19 manifestations and vaccine immunogenicity. We then discuss the limitations of currently published studies on the associations between gut microbiota and COVID-19 vaccine outcomes. Future research directions shall be focused on the development of microbiota-based interventions on improving immune response to SARS-CoV-2 infection and vaccinations.

Synergistic Antioxidant Effect of Prebiotic Ginseng Berries Extract and Probiotic Strains on Healthy and Tumoral Colorectal Cell Lines

Oxidative stress caused by reactive oxygen species (ROS, O2•−, HO•, and H2O2) affects the aging process and the development of several diseases. A new frontier on its prevention includes functional foods with both specific probiotics and natural extracts as antioxidants. In this work, Panax ginseng C.A. Meyer berries extract was characterized for the presence of beneficial molecules (54.3% pectin-based polysaccharides and 12% ginsenosides), able to specifically support probiotics growth (OD600nm > 5) with a prebiotic index of 0.49. The administration of the extract to a probiotic consortium induced the production of short-chain fatty acids (lactic, butyric, and propionic acids) and other secondary metabolites derived from the biotransformation of Ginseng components. Healthy and tumoral colorectal cell lines (CCD841 and HT-29) were then challenged with these metabolites at concentrations of 0.1, 0.5, and 1 mg/mL. The cell viability of HT-29 decreased in a dose-dependent manner after the exposition to the metabolites, while CCD841 vitality was not affected. Regarding ROS production, the metabolites protected CCD841 cells, while ROS levels were increased in HT-29 cells, potentially correlating with the less functionality of glutathione S-transferase, catalase, and total superoxide dismutase enzymes, and a significant increase in oxidized glutathione.