Periodontitis: a potential risk factor for Alzheimer's disease

A review of the risks and relationships between oral health and chronic diseases

Advances in medical science and in preventive dentistry have changed the context of oral health. The American population is living longer with numerous complex chronic diseases. This paper is to raise awareness about the impact of multiple chronic diseases and their associations with oral diseases. Comorbidities can worsen the course of dental treatment. Inflammation has been the connecting factor in the bidirectional pattern of oral and systemic diseases. High occurrences of chronic diseases generally occur in aging as well as disadvantaged populations. Serious infections, slow healing, prolonged bleeding, and hospitalizations can escalate in patients with uncontrolled chronic diseases. A multidisciplinary team-based approach to patient management can minimize complications and unexpected challenges.

Oral Microbiome Stamp in Alzheimer's Disease

Recent studies have suggested that periodontal disease and alterations in the oral microbiome may be associated with cognitive decline and Alzheimer's disease (AD) development. Here, we report a case-control study of oral microbiota diversity in AD patients compared to healthy seniors from Central Asia. We have characterized the bacterial taxonomic composition of the oral microbiome from AD patients (n = 64) compared to the healthy group (n = 71) using 16S ribosomal RNA sequencing. According to our results, the oral microbiome of AD has a higher microbial diversity, with an increase in Firmicutes and a decrease in Bacteroidetes in the AD group. LEfSe analysis showed specific differences at the genus level in both study groups. A region-based analysis of the oral microbiome compartment in AD was also performed, and specific differences were identified, along with the absence of differences in bacterial richness and on the functional side. Noteworthy findings demonstrated the decrease in periodontitis-associated bacteria in the AD group. Distinct differences were revealed in the distribution of metabolic pathways between the two study groups. Our study confirms that the oral microbiome is altered in AD. However, a comprehensive picture of the complete composition of the oral microbiome in patients with AD requires further investigation.

Association between periodontitis treatment and dementia in Taiwanese adults

BACKGROUND

The chronic systemic inflammatory response in periodontitis may be a potential risk factor for dementia, especially in adults. This study determined the association between periodontal treatment and dementia in adults and evaluated the effect of regular scaling treatment on the risk of dementia in this population.

METHODS

This case-control study identified 18,930 patients with a dementia-related diagnosis from the Taiwan National Health Insurance Research Database. Scaling and periodontal emergency treatments were evaluated after 1 year and 3 years. Using multivariable logistic regression analysis to evaluate the association between periodontal emergency treatment and dementia risk.

RESULTS

The results showed that scaling treatment rates were lower in the dementia cohort than the non-dementia cohort after 1 and 3 years. Patients who received periodontal emergency treatment within 3 years had a significantly increased risk of dementia. Furthermore, patients with periodontitis who did not receive scaling treatment within 3 years had a higher risk of dementia than patients without periodontitis (OR, 1.22; 95% CI, 1.10-1.35).

CONCLUSION

This study demonstrated that periodontitis and dementia are associated, and that periodontitis is a risk factor for dementia in adults. The risk of dementia was dependent on the periodontal health status of adults, and our findings suggest that regular scaling can reduce the incidence of dementia in adults. Therefore, regular and routine scaling treatment is suggested for adults.

Effect of Periodontal Disease on Alzheimer's Disease: A Systematic Review

The aim of this review was to evaluate the relationship between periodontal disease (PD) and the onset and progression of Alzheimer's disease (AD) and to determine whether patients with PD would be at greater risk of developing AD compared to periodontally healthy subjects. This systematic review was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. An electronic search for cross-sectional, cohort, or case-control studies was conducted on five databases (PubMed, ScienceDirect, EBSCO, Web of Science, and Scopus). No restrictions were applied to the language and year of publication. Exposure was PD, and the outcome of interest was the onset and/or progression of AD. The risk of bias of the included studies was assessed using the Newcastle-Ottawa Scale (NOS) designed for non-randomized studies. Six studies fulfilling the selection criteria were included in this systematic review. Four of the studies were of cohort design and two were of case-control design. All except one showed a significant association between PD and the risk of AD onset and progression. According to the NOS bias risk assessment, three studies were found to be of good quality, and three other cohort studies were of low quality. Data from this systematic review indicate that patients with PD present a significantly higher risk of AD compared to individuals with healthy periodontium. However, results should be interpreted with caution given the methodological limitations found. For future research, powerful and comparable epidemiological studies are needed to evaluate the relationship between PD and AD.

Guided Bone Regeneration in a Periodontally Compromised Individual with Autogenous Tooth Bone Graft: A Radiomics Analysis

BACKGROUND

Autogenous tooth bone graft material (AutoBT) has been advocated as a bone substitute when conducting alveolar ridge preservation. This study is aimed at using a radiomics approach in order to evaluate and testify whether AutoBT can stimulate bone growth during socket preservation in severe periodontal cases.

MATERIALS AND METHODS

For this study, 25 cases with severe periodontal diseases were selected. The patients' AutoBTs were inserted into the extraction sockets and covered with Bio-Gide^® collagen membranes. 3D CBCT scans and 2D X-rays were taken of the patients before surgery and after 6 months post-surgery. For the retrospective radiomics analysis, the maxillary and mandibular images were compared in different groups. Maxillary bone height was analyzed at the buccal, middle, and palatal crest sites, while the mandibular bone height was compared at the buccal, center, and lingual crest sites.

RESULTS

In the maxilla, the alveolar height was increased by -2.15 ± 2.90 mm at the buccal crest; -2.45 ± 2.36 mm at the center of the socket, and -1.62 ± 3.19 mm at the palatal crest, while the height of the buccal crest was increased by 0.19 ± 3.52 mm, and the height at the center of the socket was increased by -0.70 ± 2.71 mm in the mandible. The three-dimensional radiomics analysis demonstrated significant bone growth in the local alveolar height and high density.

CONCLUSION

Based on clinical radiomics analysis, AutoBT could be used as an alternative bone material in socket preservation after tooth extraction in patients with severe periodontitis.

Helicobacter pylori infection in the stomach induces neuroinflammation: the potential roles of bacterial outer membrane vesicles in an animal model of Alzheimer's disease

Helicobacter pylori (HP) is a Gram-negative bacterium that colonizes the human stomach chronically. Colonization of HP in the gastric mucosa not only causes gastrointestinal diseases, but also is associated with extra-gastric diseases, such as idiopathic thrombocytopenic purpura and neurological diseases. Among neurological diseases, epidemiological studies have shown that HP infection increases the prevalence of Alzheimer's disease (AD) and Parkinson's disease (PD). Since HP does not invade the central nervous system (CNS), it has been considered that systemic immunological changes induced by HP infection may play pathogenic roles in AD and PD. Here, we investigated the effects of HP infection on the CNS in vivo and in vitro. In the CNS, chronically HP-infected mice had microglial activation without HP colonization, although systemic immunological changes were not observed. This led us to explore the possibility that HP-derived outer membrane vesicles (HP-OMVs) could cause neuroinflammation. OMVs are small, spherical bilayer vesicles (20-500 nm) released into the extracellular space from the outer membrane of Gram-negative bacteria; OMVs contain lipopolysaccharide, proteins, peptidoglycan, DNA, and RNA. OMVs have also been shown to activate both innate and acquired immune cells in vitro, and to disrupt the tight junctions of the gastric epithelium ("leaky gut") as well as cross the blood-brain barrier in vivo. Thus, in theory, OMVs can activate immune responses in the remote organs, including the lymphoid organs and CNS, if only OMVs enter the systemic circulation. From the exosome fraction of sera from HP-infected mice, we detected HP-specific DNA, suggesting the presence of HP-OMVs. We also found that microglia incubated with HP-OMVs in vitro increased the cell proliferation, inflammatory cytokine production, and migration. On the other hand, HP-OMVs suppressed the cell proliferation of neuroblastoma in vitro. Lastly, we found that AD model mice infected with HP had amyloid plaques adjacent to activated microglia and astrocytes in vivo. Based on the literature review and our experimental data, we propose our working hypothesis that OMVs produced in chronic HP infection in the gut induce neuroinflammation in the CNS, explaining the higher prevalence of AD in HP-infected people.

Oral health in patients with neurodegenerative and cerebrovascular disease: a retrospective study

PURPOSE

This retrospective study investigates oral health and oral care in patients with neurodegenerative and cerebrovascular diseases (CVDs) treated in a dental facility for people with disabilities.

METHODS

Oral health indices decayed, missing, and filled teeth (DMFT), periodontal screening index (PSI), treatment spectrum, and oral hygiene were evaluated in 152 patients with multiple sclerosis, Parkinson's disease, dementia, and CVD and 30 controls. Regression analyses identified group differences and influencing factors on DMFT.

RESULTS

Patients with neurodegenerative or CVD had a significantly higher DMFT (21.2 ± 5.8 vs. 18.3 ± 5.9), more decayed teeth (4.3 ± 4.8 vs. 1 ± 1.9), fewer filled teeth (7.9 ± 5.5 vs. 11 ± 5.6), and a higher number of surgical (39.5% vs. 20%) treatments but significantly less conservative (49.3% vs. 73.3%) and prosthetic (15.1% vs. 56.7%) treatments than the control group (p< 0.05). The frequency of toothbrushing and the use of an electric toothbrush were related to lower DMFT in patients with neurodegenerative and CVD. Smoking was associated with higher DMFT.

CONCLUSIONS

Poor oral health was found in all individuals with disabilities, suggesting that limitations in oral care attributed to aging and neurological disorders negatively affect oral health. Oral rehabilitation of patients with disabilities requires awareness of oral health limitations and early intervention through dental care. Implications for rehabilitationPoor oral health and oral hygiene is common among older people with disabilities.To optimize oral rehabilitation of patients with disabilities, early intervention, individualized treatment plans and an adapted time frame for dental treatment are required.Education of dentists, caregivers, and family members is essential for oral rehabilitation and improvement of oral hygiene in patients with disabilities.

Multi-Omics Analysis Reveals the Systematic Relationship Between Oral Homeostasis and Chronic Sleep Deprivation in Rats

Sleep disorders were associated with oral health. Inflammation has especially been thought to be a key factor in linking oral diseases and sleep deficiency. However, how chronic sleep deprivation (CSD) affects oral homeostasis, particularly oral inflammation and oral microbiota, is still unknown. This study aimed to uncover the systematic relationship between oral homeostasis and CSD in rats. The metabolomics in serum, proteomics in the tongue tissues, and microbiome analysis in the oral cavity in CSD rats were performed. Multi-omics data integration analysis was performed to uncover the systematic relationship between oral homeostasis and CSD through the weighted correlation network analysis. We found that CSD could lead to oral inflammation in rats. CSD significantly increased systemic inflammation by enhancing the serum levels of IL-1β, IL-6 and inhibiting the serum level of IL-10. Serum levels of adrenocorticotropin hormone, corticosterone, and triiodothyronine were increased in CSD rats, and the steroid hormone biosynthesis pathway was also found to be involved in the perturbation resulting from CSD, together suggesting the activation of the hypothalamic-pituitary-adrenocortical and hypothalamic‐pituitary‐thyroid axis. CSD led to changes of oral microbiota composition, and g_Acinetobacter, Candidatus Chryseobacterium massiliae, and g_Moraxella were significantly correlated with multiple proteins in bacterial invasion of epithelial cells pathway, which may partially responsible for oral inflammation resulting from CSD. The changes of proteomic profiling expression caused by CSD in tongue tissues were mainly enriched in neurodegenerative diseases pathways and immune/inflammation-related pathways. Multi-omics analysis indicated that the inflammatory response-related modules were significantly correlated with the neurodegenerative disease-related module suggesting a possible link between neurodegenerative diseases and oral inflammation. Together, CSD induced oral inflammation and subtle changes on oral microbiota. Our study is helpful to further understand the role that oral homeostasis plays in the process by which CSD affects human health and disease.

Downregulation of lncRNA ANRIL Inhibits Osteogenic Differentiation of Periodontal Ligament Cells via Sponging miR-7 through NF-κB Pathway

BACKGROUND

Long noncoding RNAs (lncRNAs) are dysregulated in periodontitis development and involved in osteogenesis. The current study was aimed at investigating the function of lncRNA ANRIL in periodontal ligament cells (PDLCs) and potential molecular mechanisms.

METHODS

Firstly, the level of ANRIL was tested by qPCR. Then, PDLCs were treated with a mineralizing solution to induce osteogenic differentiation. ALP activity was measured, and protein levels of BMP2, Osterix, and OCN were measured by Western blot. A target of ANRIL was verified using dual-luciferase reporter assay. miR-7 level was measured by qPCR, and the signals of the NF-κB pathway were tested by Western blot.

RESULTS

ANRIL expression was downregulated in PDL tissues. Next, ALP activity and protein levels of BMP2, Osterix, and OCN were increased to show that PDLCs were differentiated. ANRIL level was increased in differential PDLCs, in which knockdown inhibited osteogenic differentiation. Then, miR-7 was found as a target of ANRIL. The miR-7 level was upregulated in PDL tissues and reduced in differential PDLCs. Inhibition of miR-7 suppressed ALP activity and BMP2, Osterix, and OCN expression. Moreover, inhibition of miR-7 reversed the effects on the osteogenic differentiation induced by knockdown of ANRIL. Besides, the levels of p-P65 and p-IκBα were elevated by ANRIL downregulation and were rescued by suppressing miR-7.

CONCLUSIONS

Knockdown of ANRIL inhibited osteogenic differentiation via sponging miR-7 through the NF-κB pathway, suggesting that ANRIL might be a therapeutic target for periodontitis.

Evidence and Therapeutic Perspectives in the Relationship between the Oral Microbiome and Alzheimer's Disease: A Systematic Review

This review aims to clarify the nature of the link between Alzheimer’s disease and the oral microbiome on an epidemiological and pathophysiological level, as well as to highlight new therapeutic perspectives that contribute to the management of this disease. We performed a systematic review, following the Preferred Reporting Items for Systematic Reviews checklist, from January 2000 to July 2021. The terms “plaque,” “saliva,” and “mouth” were associated with the search term “oral diseases” and used in combination with the Boolean operator “AND”/“OR”. We included experimental or clinical studies and excluded conferences, abstracts, reviews, and editorials. A total of 27 articles were selected. Evidence for the impact of the oral microbiome on the pathophysiological and immunoinflammatory mechanisms of Alzheimer’s disease is accumulating. The impact of the oral microbiome on the development of AD opens the door to complementary therapies such as phototherapy and/or the use of prebiotic compounds and probiotic strains for global or targeted modulation of the oral microbiome in order to have a favourable influence on the evolution of this pathology in the future.

A Geminated Mandibular Second Molar—A Case Report

Fusion and gemination are not entirely uncommon dental anomalies that may also be named ‘double teeth’. This is due to their unusual presentation in a twin-like fashion. Teeth with these irregularities may appear clinically similar, presenting as large and bulbous in shape with unusual anatomy and fissure patterns. The exact aetiology of these anomalies is uncertain, but many potential local or systemic disturbances during the morphodifferentiation stage of odontogenesis have been considered. Gemination occurs rarely in the permanent dentition and even less frequently in the posterior region of the oral cavity. This report presents a case of a geminated mandibular second molar and discusses the importance of early recognition and diagnosis of such teeth so that adequate preventative care and treatment can be provided.

Porphyromonas Gingivalis as a Risk Factor to Alzheimer's Disease: A Systematic Review

BACKGROUND

Alzheimer's disease (AD) is a chronic neurodegenerative disease that accounts for more than 50% of all dementia cases worldwide. There is wide consensus on the risk factors of AD; however, a clear etiology remains unknown. Evidence suggests that the inflammatory-mediated disease model, such as that found with periodontal disease due to Porphyromonas gingivalis (P. gingivalis), plays a role in AD progression.

OBJECTIVE

This study aims to systematically review the literature on the association between P. gingivalis to AD, and to identify the homogeneity of the methods used across studies to measure P. gingivalis involvement in AD.

METHODS

We systematically searched studies on Cochrane library, Ovid Medline, PubMed, Web of Science, WHOLIS, Google Scholar databases, and reference lists of identified studies.

RESULTS

6 studies out of 636 identified records fulfilled all eligibility criteria. Results showed no clear pathophysiology of AD due to P. gingivalis and its various virulence factors. No consensus was found in the literature pertaining to the method of measurement of AD or P. gingivalis and its virulence factors.

CONCLUSION

The included studies suggest that P. gingivalis bacteria play a role in the process of systemic inflammation which leads to cerebrospinal fluid inflammation and indirectly cause hastening of AD onset and progression. Our included studies revealed heterogeneity in the methodologies of measurement of AD and/or P. gingivalis and its virulence factors, which opens discussion about the benefits and weakness of possible standardization.

Gut Microbiota, Probiotic Interventions, and Cognitive Function in the Elderly: A Review of Current Knowledge

Changes in the composition and proportions of the gut microbiota may be associated with numerous diseases, including cognitive impairment. Over the recent years, the growing interest in this relation is observed, but there are still many unknowns, especially in the elderly. To the best of our knowledge, this is the first work that synthesizes and critically evaluates existing evidence on the possible association between human gut microbiota and cognitive function in the elderly. For this purpose, comprehensive literature searches were conducted using the electronic databases PubMed, Google Scholar, and ScienceDirect. The gut microbiota of cognitively healthy and impaired elderly people may differ in the diversity and abundance of individual taxes, but specific taxes cannot be identified. However, some tendencies to changing the Firmicutes/Bacteroidetes ratio can be identified. Currently, clinical trials involving probiotics, prebiotics, and synbiotics supplementation have shown that there are premises for the claim that these factors can improve cognitive functions, however there is no single intervention beneficial to the elderly population. More reliable evidence from large-scale, long-period RCT is needed. Despite proposing several potential mechanisms of the gut microbiota's influence on the cognitive function impairment, prospective research on this topic is extremely difficult to conduct due to numerous confounding factors that may affect the gut microbiota. Heterogeneity of research outcomes impairs insight into these relations.

Phenotypes, roles, and modulation of regulatory lymphocytes in periodontitis and its associated systemic diseases

Periodontitis is a common chronic inflammatory disease that can result in tooth loss and poses a risk to systemic health. Lymphocytes play important roles in periodontitis through multiple mechanisms. Regulatory lymphocytes including regulatory B cells (Bregs) and T cells (Tregs) are the main immunosuppressive cells that maintain immune homeostasis, and are critical to our understanding of the pathogenesis of periodontitis and the development of effective treatments. In this review, we discuss the phenotypes, roles, and modulating strategies of regulatory lymphocytes including Bregs and Tregs in periodontitis and frequently cooccurring inflammatory diseases such as rheumatoid arthritis, Alzheimer disease, diabetes mellitus, and stroke. The current evidence suggests that restoring immune balance through therapeutic targeting of regulatory lymphocytes is a promising strategy for the treatment of periodontitis and other systemic inflammatory diseases.

Periodontal disease is associated with cognitive dysfunction in aging dogs: A blinded prospective comparison of visual periodontal and cognitive questionnaire scores

Background

Periodontal disease has been linked to the development of Alzheimer's disease in people. It is theorized that the chronic inflammatory condition characteristic of oral dysbiosis in patients with periodontal disease leads to disruption of the blood-brain barrier, cytotoxin- and pathogen-induced brain damage, and accumulation of neurotoxic β-amyloid. In this inflammatory theory of Alzheimer's disease, β-amyloid-a known antimicrobial protein-accumulates in response to oral pathogens. Canine cognitive dysfunction (CCD) is considered a naturally occurring animal model of human Alzheimer's disease. Like humans, periodontal disease is quite common in dogs; however, a link between periodontal disease and cognitive dysfunction has not been identified in this species.

Aim

The purpose of this prospective investigation was to compare visual periodontal scores (from digital oral photographs) with numerical (0-54) cognitive assessment questionnaire forms in aging dogs with and without a clinical diagnosis of CCD.

Methods

A visual analogue scale (0-4) was used to score the severity of periodontal disease in 21 aging dogs: 11 dogs with a clinical diagnosis of presumptive CCD and 10 dogs without a clinical history of cognitive decline. Individuals scoring the dental photographs were blinded to all case information, including cognitive assessment scores. Cognitive assessment scores were compared with periodontal disease scores for all dogs.

Results

There was a significant (p < 0.05) association between periodontal and cognitive scores, with higher cognitive impairment scores being more likely in dogs with more severe periodontal disease and vice versa. No associations were identified between age and either periodontal disease or cognitive impairment.

Conclusion

Although a cause-and-effect relationship between periodontal disease and cognitive impairment cannot be ascertained from this preliminary study, we established a link between these two disorders that warrants further investigation using more stringent criteria for evaluating both periodontal disease and cognitive dysfunction.

Factors Influencing Oral Health-Related Quality of Life in Older Adults in Rural Areas: Oral Dryness and Oral Health Knowledge and Behavior

The oral health of older adults is an important factor affecting their overall health and quality of life. This study aimed to identify the characteristics of oral health of older adults living at home in rural areas and investigate factors affecting oral health-related quality of life (OHRQoL), especially oral dryness and oral health knowledge and behavior. A descriptive correlational study was conducted. In total, 117 participants were included in the final analysis. Data were collected using questionnaires for oral dryness, oral health knowledge and behavior, and OHRQoL. In addition, oral dryness was measured by mechanical measurements. Oral health knowledge was positively correlated with oral health behavior (r = 0.18, p = 0.029) and OHRQoL (r = 0.25, p = 0.003). In addition, a positive correlation between oral health behavior and OHRQoL (r = 0.24, p = 0.005) was observed. Multiple regression analysis revealed that subjective oral dryness (β = −4.99, p = 0.001) had a significant effect on OHRQoL. To improve OHRQoL in the rural elderly, health providers should pay attention to oral dryness and comprehensively evaluate it. The development of prevention programs and continuous education that can improve oral health knowledge and behavior is also required.

Can Porphyromonas gingivalis Contribute to Alzheimer's Disease Already at the Stage of Gingivitis?

Alzheimer's disease (AD) has been associated with periodontitis, which starts as gingivitis. Similar to periodontitis, gingivitis bacteria, bacterial products, and inflammatory mediators can travel to the brain via the blood stream and promote brain inflammation. Periodontal pathogens such as Porphyromonas gingivalis and Aggregatibacter actinomycetemcomitans, both associated with AD, have been found in dental plaque of children already at the age of 3. It is suggested that these bacteria during long-term exposure may drive microglia (brain resident macrophage cells) into a pro-inflammatory M1 phase where they contribute to AD rather than protect against it. This notion comes from studies in mice showing that microglia actually can "remember" previous inflammatory challenge and become "trained" or "tolerant" to toxins like lipopolysaccharide. If gingivitis has an impact on AD, which should be verified, AD prophylaxis should start already at this pre-periodontitis stage with removal of supragingival plaque.

Porphyromonas gingivalis lipopolysaccharide induces interleukin-6 and c-c motif chemokine ligand 2 expression in cultured hCMEC/D3 human brain microvascular endothelial cells

OBJECTIVE

This paper describes the effect of Porphyromonas gingivalis (P gingivalis) lipopolysaccharide (LPS) on the expression of interleukin-6 (IL-6) and C-C motif chemokine ligand 2 (CCL2) in cultured hCMEC/D3 human brain microvascular endothelial cells.

BACKGROUND

P gingivalis is one of the important pathogens in periodontitis, and periodontitis is a risk factor for brain disorders including cerebrovascular diseases and Alzheimer's disease. However, the mechanisms underlying the pathogenesis of P gingivalis-mediated brain diseases are incompletely understood. Effects of P gingivalis LPS on brain endothelial cells are not known well.

METHODS

The hCMEC/D3 human brain microvascular endothelial cells were cultured and treated with P gingivalis LPS. The expression of IL-6 and CCL2 mRNA and protein was examined using quantitative reverse transcription-polymerase chain reaction and enzyme-linked immunosorbent assay, respectively. Effect of inhibitors of Toll-like receptor (TLR) 2, TLR4, nuclear factor-κB (NF-κB), p38 mitogen-activated protein kinase (MAPK) and c-Jun N-terminal kinase (JNK) was also investigated. Phosphorylation of NF-κB p65, p38 MAPK and JNK was examined using Western blotting.

RESULTS

P gingivalis LPS-induced mRNA and protein expression of IL-6 and CCL2 in hCMEC/D3 cells in a concentration-dependent manner at the concentration of 0.5-50 µg/mL. Maximal mRNA expression of IL-6 and CCL2 was found 2 and 4 hours after stimulation, respectively. Induction of IL-6 and CCL2 by P gingivalis LPS was almost completely inhibited by pretreatment of cells with TLR4 inhibitor but not by TLR2 inhibitor. Treatment of cells with P gingivalis LPS for up to 2 hours induced phosphorylation of NF-κB p65, p38 MAPK and JNK. IL-6 induction was decreased by pretreatment of cells with NF-κB inhibitor SN50 or p38 MAPK inhibitor SB203580, while CCL2 induction was reduced by SN50 or JNK inhibitor SP600125.

CONCLUSIONS

IL-6 and CCL2 produced upon P gingivalis LPS stimulation may contribute to the inflammatory reactions in brain endothelial cells and subsequent neurological disorders such as cerebrovascular and Alzheimer's diseases.

The Potential Influence of Bone-Derived Modulators on the Progression of Alzheimer's Disease

Bone, the major structural scaffold of the human body, has recently been demonstrated to interact with several other organ systems through the actions of bone-derived cells and bone-derived cell secretory proteins. Interestingly, the brain is one organ that appears to fall into this interconnected network. Furthermore, the fact that osteoporosis and Alzheimer's disease are two common age-related disorders raises the possibility that these two organ systems are interconnected in terms of disease pathogenesis. This review focuses on the latest evidence demonstrating the impact of bone-derived cells and bone-derived proteins on the central nervous system, and on how this may be relevant in the progression of Alzheimer's disease and for the identification of novel therapeutic approaches to treat this neurodegenerative disorder.

Dental Care Utilization of Hospitalized Persons Living with HIV and Substance Use

People living with HIV (PLWH) who use drugs experience worse health outcomes than their non-using counterparts. Little is known about how often they seek dental care and the factors that influence their utilization. PLWH with substance use disorders who were inpatients at 11 urban hospitals (n = 801) participated in a National Institute on Drug Abuse Clinical Trials Network study to improve engagement in HIV outcomes. Dental care utilization at each time point during the study period (baseline, 6 months and/or 12 months) was assessed (n = 657). Univariate analysis and logistic regression were used to examine factors associated with dental care utilization. Over half (59.4%) reported not having received any dental care at any timepoint. Participants with less than high school education had lower odds of reporting dental care utilization than those with more than education (aOR = 0.60 [95% CI 0.37-0.99], p = 0.0382). Participants without health insurance also had lower odds of reporting dental care utilization than those with insurance (aOR = 0.50 [95% CI 0.331-0.76], p = 0.0012). Higher food insecurity was associated with having recent dental care utilization (OR = 1.03 [95% CI 1.00, 1.05], p = 0.0359). Additionally, those from Southern states were less likely to report dental care utilization (aOR = 0.55 [95% CI 0.38, 0.79], p = 0.0013). Having health insurance and education are key factors associated with use of dental care for PLWH with substance use disorders. The association between food insecurity and dental care utilization among this population suggests the need for further exploration.

Oral Health and Care for Elderly People with Alzheimer's Disease

Dementia is one of the main causes of disability among elderly people. It is a progressive neurodegenerative disease that affects elderly people’s ability to perform daily living activities. Alzheimer’s disease is the main subtype of dementia and causes declining memory, reasoning, and communication skills. They also have behavioural and psychological symptoms, such as depression and aggression. It is essential for them to maintain good oral health, as oral health is an important and integral part of their general health. Neglecting oral health allows dental diseases to develop, and these diseases are difficult and costly to treat. However, dental diseases can be treated with ambulatory care rather than hospitalisation and emergency care. Elderly people should establish daily oral hygiene care routines during the early stages of Alzheimer’s disease. They should have regular dental examinations and early minimal interventions to prevent the need for extensive and complicated procedures. Maintaining oral health becomes challenging, however, when Alzheimer’s disease progresses to the middle and late stages. Because elderly people might forget or lose interest in keeping their teeth healthy, caretakers and community health workers may need to take over this task. Dentists should provide guidance on the maintenance of oral health, as the techniques used to provide this support vary depending on the elderly people concerned. The purpose of this paper is to provide an overview of oral health and the importance of oral care for elderly people with Alzheimer’s disease. The paper also discusses appropriate dental interventions and techniques for maintaining good oral health and helping people with Alzheimer’s to enjoy a satisfactory quality of life.

Ligature-induced periodontitis induces systemic inflammation but does not alter acute outcome after stroke in mice

Background

Stroke is a major cause of disability and mortality. Poorer outcome after stroke is associated with concomitant inflammatory and infectious disease. Periodontitis is a chronic inflammatory disease of the dental supporting structures and is a prominent risk factor for many systemic disorders, including cardiovascular disease and stroke. While epidemiological studies suggest that periodontitis increases the likelihood of stroke, its impact on stroke severity is poorly understood. Here, we sought to determine the contribution of periodontitis to acute stroke pathology.

Methods

We characterized a murine ligature model of periodontitis for inflammatory responses that could potentially impact stroke outcome. We applied this model and then subjected mice to either transient or permanent middle cerebral artery occlusion. We also enhanced the periodontitis model with repeated intravenous administration of a periodontal-specific lipopolysaccharide to better mimic the clinical condition.

Results

Ligature-induced periodontitis caused bone loss, bacterial growth, and increased local inflammatory cell trafficking. Systemically, periodontitis increased circulating levels of pro-inflammatory cytokines, and primed bone marrow monocytes to produce elevated tumour necrosis factor-alpha (TNFα). Despite these changes, periodontitis alone or in tandem with repeated lipopolysaccharide challenge did not alter infarct volume, blood–brain barrier breakdown, or systemic inflammation after experimental stroke.

Conclusions

Our data show that despite elevated systemic inflammation in periodontitis, oral inflammatory disease does not impact acute stroke pathology in terms of severity, determined primarily by infarct volume. This indicates that, at least in this experimental paradigm, periodontitis alone does not alter acute outcome after cerebral ischemia.

Impaired innate immune signaling due to combined Toll-like receptor 2 and 4 deficiency affects both periodontitis and atherosclerosis in response to polybacterial infection

Plasma membrane-associated Toll-like receptor (TLR2 and TLR4) signaling contributes to oral microbe infection-induced periodontitis and atherosclerosis. We recently reported that either TLR2 or TLR4 receptor deficiency alters recognition of a consortium of oral pathogens, modifying host responses in periodontitis and atherosclerosis. We evaluated the effects of combined TLR2-/-TLR4-/- double knockout mice on innate immune signaling and induction of periodontitis and atherosclerosis after polybacterial infection with Porphyromonas gingivalis, Treponema denticola, Tannerella forsythia and Fusobacterium nucleatum in a mouse model. Multispecies infections established gingival colonization in all TLR2-/-TLR4-/- mice and induced production of bacterial-specific IgG antibodies. In combined TLR2-/-TLR4-/- deficiency there was, however, reduced alveolar bone resorption and mild gingival inflammation with minimal migration of junctional epithelium and infiltration of inflammatory cells. This indicates a central role for TLR2 and TLR4 in periodontitis. Atherosclerotic plaque progression was markedly reduced in infected TLR2-/-TLR4-/- mice or in heterozygotes indicating a profound effect on plaque growth. However, bacterial genomic DNA was detected in multiple organs in TLR2-/-TLR4-/- mice indicating an intravascular dissemination from gingival tissue to heart, aorta, kidney and lungs. TRL2 and TLR4 were dispensable for systemic spread after polybacterial infections but TLR2 and 4 deficiency markedly reduces atherosclerosis induced by oral bacteria.

Gingival Periodontal Disease (PD) Level-Butyric Acid Affects the Systemic Blood and Brain Organ: Insights Into the Systemic Inflammation of Periodontal Disease

Butyric acid (BA) is produced by periodontopathic bacterial pathogens and contributes to periodontal disease (PD) induction. Moreover, PD has been associated with detrimental effects which subsequently may lead to systemic disease (SD) development affecting certain organs. Surprisingly, the potential systemic manifestations and organ-localized effects of BA have never been elucidated. Here, we simulated BA-based oral infection among young (20-week-old) rats and isolated blood cytosol to determine BA effects on stress network-related signals [total heme, hydrogen peroxide (H₂O₂), catalase (CAT), glutathione reductase (GR), free fatty acid (FFA), NADP/NADPH], inflammation-associated signals [caspases (CASP12 and CASP1), IL-1β, TNF-α, metallomatrix proteinase-9 (MMP-9), and toll-like receptor-2 (TLR2)], and neurological blood biomarkers [presenilin (PS1 and PS2) and amyloid precursor protein (APP)]. Similarly, we extracted the brain from both control and BA-treated rats, isolated the major regions (hippocampus, pineal gland, hypothalamus, cerebrum, and cerebellum), and, subsequently, measured stress network-related signals [oxidative stress: total heme, NADPH, H₂O₂, GR, and FFA; ER stress: GADD153, calcium, CASP1, and CASP3] and a brain neurodegenerative biomarker (Tau). In the blood, we found that BA was no longer detectable. Nevertheless, oxidative stress and inflammation were induced. Interestingly, amounts of representative inflammatory signals (CASP12, CASP1, IL-1β, and TNF-α) decreased while MMP-9 levels increased which we believe would suggest that inflammation was MMP-9-modulated and would serve as an alternative inflammatory mechanism. Similarly, TLR2 activity was increased which would insinuate that neurological blood biomarkers (APP, PS1, and PS2) were likewise affected. In the brain, BA was not detected, however, we found that both oxidative and ER stresses were likewise altered in all brain regions. Interestingly, tau protein amounts were significantly affected in the cerebellar and hippocampal regions which coincidentally are the major brain regions affected in several neurological disorders. Taken together, we propose that gingival BA can potentially cause systemic inflammation ascribable to prolonged systemic manifestations in the blood and localized detrimental effects within the brain organ.

Health and quality of life differ between community living older people with and without remaining teeth who recently received formal home care: a cross sectional study

Objective

To assess oral health, health, and quality of life (QoL) of care-dependent community-living older people with and without remaining teeth who recently received formal home care.

Materials and methods

For this cross-sectional observational study, community-living older people (≥ 65 years), who recently (< 6 months) received formal home care, were interviewed with validated questionnaires and underwent an oral examination. Oral health, general health, medicines usage, frailty (Groningen Frailty Indicator), cognition (Minimal Mental State Examination), QoL (RAND 36), and oral health-related QoL (Oral Health Impact Profile-14) were assessed.

Results

One hundred three out of 275 consecutive eligible older people (median age 79 [IQR (Inter Quartile Range) 72–85 years] participated in the study. Thirty-nine patients had remaining teeth and 64 were edentulous. Compared with edentulous older people, older people with remaining teeth scored significantly better on frailty, QoL, physical functioning, and general health. No significant differences were seen in cognition. Dental and periodontal problems were seen in more than half of the patients with remaining teeth. Two third of the edentulous patients did not visit their dentist regularly or at all.

Conclusions

Care-dependent home-dwelling older people with remaining teeth generally were less frail, scored better on physical functioning and general health and had better QoL than edentulous older people. Dental and periodontal problems were seen in approximately 50% of the elderly.

Clinical relevance

Notwithstanding their common dental problems, frailty, health, and QoL are better in home-dwelling older people with remaining teeth. To maintain this status, we advise not only dentists, but also health care workers and governments, to encourage people to maintain good oral health.

Patients with Chronic Obstructive Pulmonary Disease Suffer from Worse Periodontal Health-Evidence from a Meta-Analysis

Background and Objective: It is widely accepted that there is an association between chronic obstructive pulmonary disease (COPD) and periodontitis. However, whether the periodontal status of the COPD patients is worse than that of the non-COPD subjects is seldom assessed. The findings currently available are inconsistent, some even contradictory. Therefore, we performed this meta-analysis to compare the periodontal health status of COPD patients and non-COPD subjects. Methods: PubMed and Embase were searched for all of the eligible studies which comparing the periodontal status between COPD patients and non-COPD subjects. The results of periodontal parameters in each study were extracted and the mean differences and 95% confidence intervals (CIs) for each parameter were calculated to determine their overall effects. Results: In total, 14 studies involving 3348 COPD patients and 20612 non-COPD controls were included and 9 periodontal indexes were analyzed. The mean differences (95% CIs) between COPD and non-COPD subjects for probing depth, clinical attachment loss, level of alveolar bone loss, plaque index, oral hygiene index, bleeding index, bleeding on probing, gingival index, and remaining teeth were 0.261 (0.020-0.501), 0.480 (0.280-0.681), 0.127 (0.000-0.254), 0.226 (0.043-0.408), 0.802 (0.326-1.279), 0.241 (-0.106 to 0.588), 6.878 (5.489-8.266), 0.364 (0.036-0.692), and -3.726 (-5.120 to -2.331), respectively. Conclusion: In summary, this meta-analysis demonstrates that the COPD patients suffer from worse periodontal health status, indicated by deeper periodontal pockets, high level of clinical attachment loss, worse oral hygiene, more inflammation and bleeding in the gingival tissue, and lower number of remaining teeth. Nevertheless, considering the limitations in our meta-analysis, more high-quality, and well-designed studies focusing on the periodontal health of the COPD patients are required to validate our conclusion.

Periodontitis and Alzheimer's Disease: A Possible Comorbidity between Oral Chronic Inflammatory Condition and Neuroinflammation

Periodontitis is an oral chronic infection/inflammatory condition, identified as a source of mediators of inflammation into the blood circulation, which may contribute to exacerbate several diseases. There is increasing evidence that inflammation plays a key role in the pathophysiology of Alzheimer’s disease (AD). Although inflammation is present in both diseases, the exact mechanisms and crosslinks between periodontitis and AD are poorly understood. Therefore, this article aims to review possible comorbidity between periodontitis and AD. Here, the authors discuss the inflammatory aspects of periodontitis, how this oral condition produces a systemic inflammation and, finally, the contribution of this systemic inflammation for worsening neuroinflammation in the progression of AD.

16S rRNA Next Generation Sequencing Analysis Shows Bacteria in Alzheimer's Post-Mortem Brain

The neurological deterioration associated with Alzheimer's disease (AD), involving accumulation of amyloid-beta peptides and neurofibrillary tangles, is associated with evident neuroinflammation. This is now seen to be a significant contributor to pathology. Recently the tenet of the privileged status of the brain, regarding microbial compromise, has been questioned, particularly in terms of neurodegenerative diseases. It is now being considered that microbiological incursion into the central nervous system could be either an initiator or significant contributor to these. This is a novel study using 16S ribosomal gene-specific Next generation sequencing (NGS) of extracted brain tissue. A comparison was made of the bacterial species content of both frozen and formaldehyde fixed sections of a small cohort of Alzheimer-affected cases with those of cognitively unimpaired (normal). Our findings suggest an increase in bacterial populations in Alzheimer brain tissue compared with normal.

Study protocol: Insight 46 - a neuroscience sub-study of the MRC National Survey of Health and Development

BACKGROUND

Increasing age is the biggest risk factor for dementia, of which Alzheimer's disease is the commonest cause. The pathological changes underpinning Alzheimer's disease are thought to develop at least a decade prior to the onset of symptoms. Molecular positron emission tomography and multi-modal magnetic resonance imaging allow key pathological processes underpinning cognitive impairment - including β-amyloid depostion, vascular disease, network breakdown and atrophy - to be assessed repeatedly and non-invasively. This enables potential determinants of dementia to be delineated earlier, and therefore opens a pre-symptomatic window where intervention may prevent the onset of cognitive symptoms.

METHODS/DESIGN

This paper outlines the clinical, cognitive and imaging protocol of "Insight 46", a neuroscience sub-study of the MRC National Survey of Health and Development. This is one of the oldest British birth cohort studies and has followed 5362 individuals since their birth in England, Scotland and Wales during one week in March 1946. These individuals have been tracked in 24 waves of data collection incorporating a wide range of health and functional measures, including repeat measures of cognitive function. Now aged 71 years, a small fraction have overt dementia, but estimates suggest that ~1/3 of individuals in this age group may be in the preclinical stages of Alzheimer's disease. Insight 46 is recruiting 500 study members selected at random from those who attended a clinical visit at 60-64 years and on whom relevant lifecourse data are available. We describe the sub-study design and protocol which involves a prospective two time-point (0, 24 month) data collection covering clinical, neuropsychological, β-amyloid positron emission tomography and magnetic resonance imaging, biomarker and genetic information. Data collection started in 2015 (age 69) and aims to be completed in 2019 (age 73).

DISCUSSION

Through the integration of data on the socioeconomic environment and on physical, psychological and cognitive function from 0 to 69 years, coupled with genetics, structural and molecular imaging, and intensive cognitive and neurological phenotyping, Insight 46 aims to identify lifetime factors which influence brain health and cognitive ageing, with particular focus on Alzheimer's disease and cerebrovascular disease. This will provide an evidence base for the rational design of disease-modifying trials.

Alzheimer's Disease: Exploring the Role of Inflammation and Implications for Treatment

Alzheimer's disease (AD) is a neurodegenerative disorder characterized by both structural abnormalities and inflammation in the brain. While recent research has chiefly focused on the structural changes involved in AD, understanding the pathophysiology and associated inflammation of the AD brain helps to elucidate potential therapeutic and preventative options. By exploring the data supporting an inflammatory etiology of AD, we present a case for the use of existing evidence-based treatments addressing inflammation as promising options for treating and preventing AD. We present data demonstrating tumor necrosis factor alpha association with the inflammation of AD. We also discuss data supporting TNF alpha associated inflammation in traumatic brain injury, stroke, and spinal disc associated radiculopathy. We augment this previously unarticulated concept of a unifying pathophysiology of central nervous system disease, with reports of benefits of TNF alpha inhibition in many hundreds of patients with those diseases, including AD. We also assess the pathophysiologic and clinical trial evidence supporting the role of other inflammation resolving treatments in AD. In aggregate, the data from the several potentially effective therapeutic and preventative options contained within this report presents a clearer picture of next steps needed in research of treatment alternatives.

Can oral infection be a risk factor for Alzheimer's disease?

Alzheimer's disease (AD) is a scourge of longevity that will drain enormous resources from public health budgets in the future. Currently, there is no diagnostic biomarker and/or treatment for this most common form of dementia in humans. AD can be of early familial-onset or sporadic with a late-onset. Apart from the two main hallmarks, amyloid-beta and neurofibrillary tangles, inflammation is a characteristic feature of AD neuropathology. Inflammation may be caused by a local central nervous system insult and/or by peripheral infections. Numerous microorganisms are suspected in AD brains ranging from bacteria (mainly oral and non-oral Treponema species), viruses (herpes simplex type I), and yeasts (Candida species). A causal relationship between periodontal pathogens and non-oral Treponema species of bacteria has been proposed via the amyloid-beta and inflammatory links. Periodontitis constitutes a peripheral oral infection that can provide the brain with intact bacteria and virulence factors and inflammatory mediators due to daily, transient bacteremias. If and when genetic risk factors meet environmental risk factors in the brain, disease is expressed, in which neurocognition may be impacted, leading to the development of dementia. To achieve the goal of finding a diagnostic biomarker and possible prophylactic treatment for AD, there is an initial need to solve the etiological puzzle contributing to its pathogenesis. This review therefore addresses oral infection as the plausible etiology of late-onset AD (LOAD).