Gut microbiota and the periodontal disease: role of hyperhomocysteinemia

Mendelian Randomisation Study on Association of Gut Microbiota and Periodontitis

OBJECTIVE

Several studies have demonstrated the possible association between gut microbiota and periodontitis. The mechanism by which gut microbiota contribute to periodontitis remains unknown.

METHODS

A 2-sample Mendelian randomisation (MR) study was conducted using publicly available Genome-Wide Association Studies (GWAS) data of European ancestry. The relationships between gut microbiota and tooth loss and periodontitis were assessed using summary-level data. Moreover, inverse variance weighted (IVW), MR-Egger, weighted median, and simple Mendelian were used. The results were further validated using sensitivity analyses.

RESULTS

A total of 211 gut microbiota were studied, including 9 phyla, 16 classes, 20 orders, 35 families, and 131 genera. The IVW method identified 16 bacterial genera related to the risk of periodontitis and tooth loss. Lactobacillaceae was associated with an increased risk of periodontitis (odds ratio [OR], 1.40, 95% confidence interval [CI], 1.03-1.91, P<.001) and tooth loss (OR, 1.12; 95% CIs, 1.02-1.24, P = .002), whereas Lachnospiraceae UCG008 was linked to a lower risk of tooth loss (P = .041). There was no heterogeneity and horizontal pleiotropy in the sensitivity analysis.

CONCLUSIONS

Several microorganisms were identified to be linked to the risk of periodontitis. Furthermore, the findings improved our understanding of gut microbiota and periodontitis pathology.

Effect of systemic administration of Bifidobacterium animalis subsp. lactis HN019 on apical periodontitis

This study aimed to evaluate the effect of Bifidobacterium animalis subsp. lactis (B. lactis) HN019 in drinking water on the development of apical periodontitis (AP) in rats. In total 60 animals were divided into a control group (sound teeth); Group I - regular water without AP; Group II - probiotic water without AP; Group III - regular water with AP; Group IV - probiotic water with AP. AP was induced after 3 days in the control groups and after 7, 21, and 42 days in groups III and IV. The animals were euthanized, and the mandibles were subjected to histotechnical processing. Samples were stained with hematoxylin & eosin (H&E) to identify root canal features, apical and periapical regions. Additionally, histoenzymology was performed to detect osteoclasts, immunohistochemistry was used to identify osteoclastogenesis markers, and the Brown & Brenn technique was applied for microbiological analysis. The data were analyzed using GraphPad Prism 8.0.1 with a significance level of 5%. Although no statistical differences were observed, the groups administered with probiotics showed better conditions in terms of histological aspects seen microscopically. Furthermore, there were no differences in the number of osteoclasts (p > 0.05). The RANKL marker was not found in the probiotic group at 42 days, unlike in group III.

Regulatory effects of oral microbe on intestinal microbiota and the illness

Over the past decade, the association between oral health, intestinal microbiota, and systemic diseases has been further validated. Some oral microbial species have been isolated from pathological intestine mucosa or feces and identified as biomarkers for intestinal diseases. A small proportion of oral microbiome passes through or colonizes the lower gastrointestinal tract, even in healthy individuals. Opportunistic pathogens from the oral cavity may expand and participate in the occurrence and progression of intestinal diseases when the anatomical barrier is disrupted. These disruptors interact with the intestinal microbiota, disturbing indigenous microorganisms, and mucosal barriers through direct colonization, blood circulation, or derived metabolite pathways. While interacting with the host's immune system, oral-derived pathogens stimulate inflammation responses and guide the transition of the intestinal microenvironment from a healthy state to a pre-disease state. Therefore, the oral-gut microbiome axis sheds light on new clinical therapy options, and gastrointestinal tract ecology balance necessitates simultaneous consideration of both oral and gut microbiomes. This review summarizes possible routes of oral microbes entering the intestine and the effects of certain oral bacteria on intestinal microbiota and the host's immune responses.

Gut microbiome sheds light on the development and treatment of abdominal aortic aneurysm

Abdominal aortic aneurysm (AAA) is an inflammatory vascular disease with high disability and mortality. Its susceptible risk factors include old age, being male, smoking, hypertension, and aortic atherosclerosis. With the improvement of screening techniques, AAA incidence and number of deaths caused by aneurysm rupture increase annually, attracting much clinical attention. Due to the lack of non-invasive treatment, early detection and development of novel treatment of AAA is an urgent clinical concern. The pathophysiology and progression of AAA are characterized by inflammatory destruction. The gut microbiota is an "invisible organ" that directly or indirectly affects the vascular wall inflammatory cell infiltration manifested with enhanced arterial wall gut microbiota and metabolites, which plays an important role in the formation and progression of AAA. As such, the gut microbiome may become an important risk factor for AAA. This review summarizes the direct and indirect effects of the gut microbiome on the pathogenesis of AAA and highlights the gut microbiome-mediated inflammatory responses and discoveries of relevant therapeutic targets that may help manage the development and rupture of AAA.

Intestinal toxicity of micro- and nano-particles of foodborne titanium dioxide in juvenile mice: Disorders of gut microbiota-host co-metabolites and intestinal barrier damage

The wide use of TiO₂ particles in food and the high exposure risk to children have prompted research into the health risks of TiO₂. We used the microbiome and targeted metabolomics to explore the potential mechanism of intestinal toxicity of foodborne TiO₂ micro-/nanoparticles after oral exposure for 28 days in juvenile mice. Results showed that the gut microbiota-including the abundance of Bacteroides, Bifidobacterium, Lactobacillus, and Prevotella-changed dynamically during exposure. The organic inflammatory response was activated, and lipopolysaccharide levels increased. Intestinal toxicity manifested as increased mucosal permeability, impaired intestinal barrier, immune damage, and pathological changes. The expression of antimicrobial peptides, occludin, and ZO-1 significantly reduced, while that of JNK2 and Src/pSrc increased. Compared with micro-TiO₂ particles, the nano-TiO₂ particles had strong toxicity. Fecal microbiota transplant confirmed the key role of gut microbiota in intestinal toxicity. The levels of gut microbiota-host co-metabolites, including pyroglutamic acid, L-glutamic acid, phenylacetic acid, and 3-hydroxyphenylacetic acid, changed significantly. Significant changes were observed in the glutathione and propanoate metabolic pathways. There was a significant correlation between the changes in gut microbiota, metabolites, and intestinal cytokine levels. These, together with the intestinal barrier damage signaling pathway, constitute the network mechanism of the intestinal toxicity of TiO₂ particles.

Colorectal Cancer, Gut Microbiota and Traditional Chinese Medicine: A Systematic Review

Based on the study and research on the pathogenesis of colorectal cancer, the types and functions of gut microbiota, and its role in guiding and regulating the occurrence and development of diseases, we have explored the mechanism of traditional Chinese medicine in the treatment of colorectal cancer by regulating the gut microbiota. Genetic variation, abnormal responses of innate and adaptive immunity, mucosal barrier dysfunction, imbalance of intestinal microbial colonization, personal and environmental risk factors are the main pathogenesis of colorectal cancer. The gut microbiota mainly includes Sclerotium (including Clostridium, Enterococcus, Lactobacillus and Ruminococcus) and Bacteroides (including Bacteroides and Prevotella), which have biological antagonism, nutrition for the organism, metabolic abilities, immune stimulation, and ability to shape cancer genes functions to body. The gut microbiota can be related to the health of the host. Current studies have shown that Chinese herbal compound, single medicinal materials, and monomer components can treat colorectal cancer by regulating the gut microbiota, such as Xiaoyaosan can increase the abundance of Bacteroides, Lactobacillus, and Proteus and decrease the abundance of Desulfovibrio and Rickerella. Therefore, studying the regulation and mechanism of gut microbiota on colorectal cancer is of great benefit to disease treatment.

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.