Human Microbiota Influence on Human Health Status 2.0

A special issue of Applied Microbiology (ISSN 2673-8007).

Deadline for manuscript submissions: closed (30 September 2023) | Viewed by 12494

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Department of Public Health and Infection Disease, Microbiology Section, Sapienza University of Rome, 00185 Rome, Italy
Interests: microorganism/host interactions; pathogenesis mechanisms; innovative therapies
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Special Issue Information

Dear Colleagues,

This Special Issue is the continuation of our previous Special Issue “Human Microbiota Influence on Human Health Status”.

Microbes colonize all living organisms, and the microbial communities that peacefully coexist with the host are collectively called “microbiota”. In this microbial ecosystem, in addition to bacteria are also present eukaryotes, viruses, and bacteriophages. The overall microbiota genome, named the microbiome, has a coding capacity that far exceeds that of the human genome, providing functional characteristics that humans have not evolved. This has given rise to the perception that humans are hybrid super-organisms made up of human cells and microbial cells. These microbial communities begin to assemble on us before we are born, and follow us throughout our life, strongly influencing our state of health. Today even compartments which have always been considered sterile appear to be colonized; several research works report a blood microbiota, or a lung microbiota. The term dysbiosis indicates an ecosystem where bacteria no longer live together in mutual harmony. The list of pathologies related to this status is increasing day by day.

The focus of this Special Issue is on the assembly of original research and review articles on human microbiota (skin, nasal, oral, gut, vaginal, blood, lung, etc.) and its impact on human health status.

Dr. Serena Schippa
Guest Editor

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Published Papers (6 papers)

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Research

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11 pages, 609 KiB  
Article
The Dose Response Effects of Partially Hydrolyzed Guar Gum on Gut Microbiome of Healthy Adults
by Megan Edelman, Qi Wang, Rylee Ahnen and Joanne Slavin
Appl. Microbiol. 2024, 4(2), 720-730; https://doi.org/10.3390/applmicrobiol4020049 - 27 Apr 2024
Viewed by 1021
Abstract
Partially hydrolyzed guar gum (PHGG) is a water-soluble, prebiotic fiber that is used in foods and supplements. The effects of PHGG and its role in gut health are still being studied. The purpose of this study was to evaluate changes in the gut [...] Read more.
Partially hydrolyzed guar gum (PHGG) is a water-soluble, prebiotic fiber that is used in foods and supplements. The effects of PHGG and its role in gut health are still being studied. The purpose of this study was to evaluate changes in the gut microbiome composition of healthy individuals in response to low-dose PHGG supplementation compared with a low fiber diet. A randomized, double-blind, placebo-controlled crossover study was performed on 33 healthy subjects (17 males, 16 females). Each subject completed three 14-day treatment periods with a 2-week washout between each period. Treatments included supplementation with 3 g PHGG, 6 g PHGG, or a placebo. During all periods, the participants followed a low fiber diet (≤14 g/day). Stools were collected on days 0 and 14 of each period. Gut microbiome profiling was performed using 16S rRNA sequencing. Stools were assessed by investigators with the Bristol Stool Form Scale as a secondary outcome. Saliva cortisol was also measured as a secondary outcome. Supplementation of 3 g and 6 g PHGG significantly increased Verrucomicrobia on day 14 when compared to the placebo (p = 0.0066 and p = 0.0068, respectively). On the genus level, Akkermansia was significantly increased on day 14 with both the 3 g and 6 g PHGG doses (p = 0.0081 and p = 0.0083). Faecalibacterium was significantly decreased on day 14 with 3 g PHGG (p = 0.0054). Supplementing with low doses of PHGG has the potential to cause shifts in the gut microbiome composition. By increasing beneficial microbes, PHGG can improve the microbiome composition of healthy individuals and may play a role in the treatment of inflammatory gastrointestinal diseases. Full article
(This article belongs to the Special Issue Human Microbiota Influence on Human Health Status 2.0)
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15 pages, 3262 KiB  
Article
Porphyromonas gingivalis Strain W83 Infection Induces Liver Injury in Experimental Alcohol-Associated Liver Disease (ALD) in Mice
by Yun Zhou, Craig McClain and Wenke Feng
Appl. Microbiol. 2024, 4(2), 620-634; https://doi.org/10.3390/applmicrobiol4020043 - 27 Mar 2024
Viewed by 740
Abstract
The liver plays a vital role in the defense against infections. Porphyromonas gingivalis (P. gingivalis), a dominant etiologic oral bacterium implicated in periodontal disease (PD), has been associated with various systemic diseases. This study aimed to investigate the influence of P. [...] Read more.
The liver plays a vital role in the defense against infections. Porphyromonas gingivalis (P. gingivalis), a dominant etiologic oral bacterium implicated in periodontal disease (PD), has been associated with various systemic diseases. This study aimed to investigate the influence of P. gingivalis on alcohol-associated liver diseases (ALD). Mice were fed a Lieber–DeCarli liquid diet containing 5% ethanol for 10 days after an initial adaptation period on a diet with lower ethanol content for 7 days. Two days before tissue sample collection, the mice were administered P. gingivalis strain W83 (Pg) through intraperitoneal injection (IP). Pair-fed mice with Pg infection (PF+Pg) exhibited an activated immune response to combat infections. However, alcohol-fed mice with Pg infection (AF+Pg) showed liver injury with noticeable abscess lesions and elevated serum alanine aminotransferase (ALT) levels. Additionally, these mice displayed liver infiltration of inflammatory monocytes and significant downregulation of proinflammatory cytokine gene expression levels; and AF+Pg mice also demonstrated increased intrahepatic neutrophil infiltration, as confirmed by chloroacetate esterase (CAE) staining, along with elevated gene expression levels of neutrophil cytosol factor 1 (Ncf1), neutrophilic inflammation driver lipocalin 2 (Lcn2), and complement component C5a receptor 1 (C5ar1), which are associated with neutrophilic inflammation. Interestingly, compared to PF+Pg mice, the livers of AF+Pg mice exhibited downregulation of gene expression levels of NADPH oxidase 2 (Cybb), the leukocyte adhesion molecule Cd18, and the Toll-like receptor adaptor Myd88. Consequently, impaired clearance of P. gingivalis and other bacteria in the liver, increased susceptibility to infections, and inflammation-associated hepatic necrotic cell death were observed in AF+Pg mice, which is likely to have facilitated immune cell infiltration and contributed to liver injury. Furthermore, in addition to the Srebf1/Fasn pathway induced by alcohol feeding, Pg infection also activated carbohydrate response element-binding protein (ChREBP) in AF+Pg mice. In summary, this study demonstrates that P. gingivalis infection, acting as a “second hit”, induces dysfunction of immune response and impairs the clearance of bacteria and infections in alcohol-sensitized livers. This process drives the development of liver injury. Full article
(This article belongs to the Special Issue Human Microbiota Influence on Human Health Status 2.0)
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12 pages, 2219 KiB  
Article
The Probiotic Streptococcus salivarius M18 Increases Plasma Nitrite but Does Not Alter Blood Pressure: A Pilot Randomised Controlled Trial
by Mia C. Burleigh, Bob T. Rosier, Annabel Simpson, Nicholas Sculthorpe, Fiona Henriquez and Chris Easton
Appl. Microbiol. 2023, 3(3), 774-785; https://doi.org/10.3390/applmicrobiol3030054 - 13 Jul 2023
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Abstract
Some species of oral bacteria can reduce dietary nitrate to nitrite, which can later be converted to nitric oxide in the nitrate—nitrite—nitic oxide pathway. Increasing nitric oxide availability can reduce blood pressure (BP) and improve exercise performance. Streptococcus salivarius M18 (Streptococcus salivarius [...] Read more.
Some species of oral bacteria can reduce dietary nitrate to nitrite, which can later be converted to nitric oxide in the nitrate—nitrite—nitic oxide pathway. Increasing nitric oxide availability can reduce blood pressure (BP) and improve exercise performance. Streptococcus salivarius M18 (Streptococcus salivarius M18) is a bacteriocin-producing probiotic that is known to improve oral health by inhibiting pathogenic oral bacteria. However, it is presently unclear whether probiotic-induced alterations to the oral microbiome will influence circulating levels of nitric oxide metabolites and BP. Purpose: To determine the effects of Streptococcus salivarius M18 supplementation on plasma and salivary nitrate and nitrite levels and BP. Methods: Ten healthy males (age 32 ± 8 y, body mass 88.2 ± 15.1 kg) completed 2 × 14-day supplementation phases in a randomized order at least 14 days apart. In one phase, participants consumed Streptococcus salivarius M18 probiotic lozenges (2.5 billion colony-forming units/dose) once per day, and in the other, they ingested water (placebo). The abundance of bacteria on the tongue was assessed via Illumina 16S rRNA gene sequencing, unstimulated saliva, and venous blood samples were collected, and BP was measured pre and post each phase. Saliva and plasma were analysed for nitrate and nitrite using chemiluminescence, and pH was measured in saliva. The change in each outcome from pre- to post-supplementation was compared between phases using repeated measures ANOVA. Results: Plasma nitrite increased from baseline following probiotic supplementation (from 173 ± 39 to 223 ± 63 nM, p = 0.003, 95% CI 192–250 nM). In comparison, there was no change in the placebo phase or between baselines (all p > 0.05). The abundance of nitrite-producing bacteria was not altered, salivary nitric oxide metabolites and pH did not change, and the increase in plasma nitrite did not result in reductions in BP (all p > 0.05). Conclusions: Supplementation with Streptococcus salivarius M18 increased plasma nitrite, a key marker of NO availability. Despite this, Streptococcus salivarius M18 did not lower BP in these healthy normotensive participants. Additionally, the increase in plasma nitrite was not associated with abundance changes in bacteria thought important to NO generation. Further research is required to determine the mechanism behind the increase in plasma nitrite and the potential therapeutic and ergogenic benefits of Streptococcus salivarius M18 supplementation. Full article
(This article belongs to the Special Issue Human Microbiota Influence on Human Health Status 2.0)
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Review

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23 pages, 392 KiB  
Review
The Human Superorganism: Using Microbes for Freedom vs. Fear
by Rodney R. Dietert and Janice M. Dietert
Appl. Microbiol. 2023, 3(3), 883-905; https://doi.org/10.3390/applmicrobiol3030061 - 10 Aug 2023
Cited by 1 | Viewed by 2122
Abstract
Balanced fear supports human rational decision-making and useful behavioral responses. In contrast, overwhelming, persistent, and unbalanced fear can paralyze the individual and result in heightened anxiety, lack of cognitive flexibility, fear-based public compliance and serious mental health issues. Psychobiotics research has established that [...] Read more.
Balanced fear supports human rational decision-making and useful behavioral responses. In contrast, overwhelming, persistent, and unbalanced fear can paralyze the individual and result in heightened anxiety, lack of cognitive flexibility, fear-based public compliance and serious mental health issues. Psychobiotics research has established that a healthy microbiome is required for balanced fear and mental health protection via control of fear extinction. The recent COVID-19 pandemic featured daily, persistent, fear-of-a-single-contagion conditioning on a global scale paired with various behavioral mandates (e.g., lockdowns of the healthy, required wearing of face masks in many locations including schools, isolation from environmental microbes and each other through the closure of beaches and parks, and restrictions on social gatherings including access to family members in hospitals and senior-assisted facilities). Such mandates degraded the human microbiome and isolated us from each other and useful environmental microbes. It also ignored the historic role of secondary bacterial pathogens in pandemic deaths. This narrative review examines how the institutional promotion of fear-of-a-single-contagion, lack of balanced risk communication, and appalling disregard of our fundamental nature (as majority-microbial human superorganisms) resulted in problems rather than solutions. This review illustrates that government-public health-media promotion of pervasive fear and microbiome-degrading behaviors: (1) increased public compliance, (2) reduced cognitive flexibility, and (3) increased risk of mental health conditions. However, a portion of the general public chose a healthier path through their increased consumption of microbiome- and immune-supportive supplements and fermented foods during and after the COVID-19 pandemic. For a healthier future, public health must follow the lead of this population to ensure that human freedom, rather than paralyzing fear, dominates our future. Full article
(This article belongs to the Special Issue Human Microbiota Influence on Human Health Status 2.0)
19 pages, 1158 KiB  
Review
The Role of an Altered Gut Microbiome in Parkinson’s Disease: A Narrative Review
by Sara Hashish and Mohamed Salama
Appl. Microbiol. 2023, 3(2), 429-447; https://doi.org/10.3390/applmicrobiol3020030 - 10 May 2023
Cited by 6 | Viewed by 3424
Abstract
Parkinson’s disease is a debilitating multisystemic disorder affecting both the central and peripheral nervous systems. Accumulating evidence suggests a potential interaction between gut microbiota and the pathophysiology of the disease. As a result of the degradation of dopaminergic neurons, PD patients develop motor [...] Read more.
Parkinson’s disease is a debilitating multisystemic disorder affecting both the central and peripheral nervous systems. Accumulating evidence suggests a potential interaction between gut microbiota and the pathophysiology of the disease. As a result of the degradation of dopaminergic neurons, PD patients develop motor impairments such as tremors, rigidity, and slowness of movement. These motor features are preceded by gastrointestinal issues, including constipation. Given these gastrointestinal issues, the gut has emerged as a potential modulator of the neurodegenerative cascade of PD. Several studies have been carried out to broaden our understanding of the gut–microbiota–brain axis in PD. As a result, a decrease in short-chain fatty acid synthesizing bacteria has been observed in multiple studies. Some studies, on the other hand, have shown an enrichment of mucin- and levodopa-degrading microbes. In this review, we compiled the available evidence from the literature on the bidirectional communication between the gut microbiome system and the brain in PD. We also addressed the association between dysbiosis and the clinical symptoms of PD and host–drug metabolism. Finally, we touched on some of the therapeutic interventions that may restore eubiosis and modulate the gut structure to restrain disease progression. Full article
(This article belongs to the Special Issue Human Microbiota Influence on Human Health Status 2.0)
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Other

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10 pages, 1209 KiB  
Brief Report
Selective Change in the Bacteria Cultured and Isolated in Respiratory Sputum from Elderly Patients during the SARS-CoV-2 Pandemic
by Masayuki Nagasawa, Tomoyuki Kato, Ippei Tanaka and Emi Ono
Appl. Microbiol. 2023, 3(3), 1003-1012; https://doi.org/10.3390/applmicrobiol3030068 - 23 Aug 2023
Viewed by 1028
Abstract
The SARS-CoV-2 pandemic has affected social patterns and consequently the prevalence of infections, such as seasonal influenza. It has been reported that invasive pneumococcal infection has markedly decreased worldwide. Method: We retrospectively investigated the bacteria cultured and isolated from 23,052 respiratory sputum samples [...] Read more.
The SARS-CoV-2 pandemic has affected social patterns and consequently the prevalence of infections, such as seasonal influenza. It has been reported that invasive pneumococcal infection has markedly decreased worldwide. Method: We retrospectively investigated the bacteria cultured and isolated from 23,052 respiratory sputum samples obtained at our hospital from April 2015 to March 2022. The average patient age was 71.8 years old, with a standard deviation of 16.0 years old. There was no significant difference in the age of the patients or the female-to-male ratio between each year. The detection ratio of bacteria was analyzed in accordance with sputum quality based on the Geckler classification. Results: The detection ratio of community-acquired pneumonia pathogens such as Haemophilus influenzae, Moraxella catarrhalis, and Streptococcus pneumoniae increased in parallel with the quality of the sputum, while that of hospital-acquired pneumonia pathogens such as Klebsiella pneumoniae, Pseudomonas aeruginosa, and Staphylococcus aureus was not significantly affected by the quality of the sputum. The detection ratio of former pathogens in the good-quality respiratory sputum had decreased significantly since April 2020 by 60–80%, while that of P. aeruginosa and S. aureus had increased by 40–50%. Conclusions: The SARS-CoV-2 pandemic reduced the detection ratio of H. influenzae, M. catarrhalis, and S. pneumoniae but increased that of P. aeruginosa and S. aureus in the good-quality respiratory sputum from elderly patients. The influence of this selective change in isolated bacteria on the health and comorbidity of elderly patients remains to be investigated. Full article
(This article belongs to the Special Issue Human Microbiota Influence on Human Health Status 2.0)
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