The Effect of Dietary Advice Aimed at Increasing Protein Intake on Oral Health and Oral Microbiota in Older Adults: A Randomized Controlled Trial.

Nutrition and oral health are closely related, especially in older adults in whom poor nutrition may lead to oral microbial perturbations, exacerbating poor oral health. In a 6-month randomized controlled trial, we evaluated the effects on oral microbiota and on oral health of dietary advice aimed at increasing protein intake to ≥1.2 g/kg adjusted body weight/day (g/kg aBW/d) in community-dwelling older adults with low habitual protein intake (<1.0 g/kg aBW/d). Food intake was measured via 24 h dietary recalls, oral health was measured via questionnaires, and oral microbial composition was assessed via the 16S rRNA sequencing of tongue swabs. Mean baseline protein intake was 0.8 g/kg aBW/day in both groups. In the high protein group (n = 47), participants increased their protein intake to mean 1.2 g/kg aBW/day at the 6-month follow-up. Protein intake in the control group (n = 43) remained at 0.9 g/kg a BW/day. The intervention did not affect self-reported oral health. While it caused moderate shifts in oral microbiota alpha- and beta-diversity measures, abundances of individual bacterial taxa were not affected. In conclusion, our intervention did not affect self-reported oral health within a period of 6 months, nor did it substantially affect the tongue microbiota composition.

The entero-endocrine response following a mixed-meal tolerance test with a non-nutritive pre-load in participants with pre-diabetes and type 2 diabetes: A crossover randomized controlled trial proof of concept study.

INTRODUCTION: This crossover randomized controlled trial (RCT) investigated differences in short-term entero-endocrine response to a mixed-meal tolerance test preceded by nutrient sensing between participants with pre-diabetes (pre-T2D) and type 2 diabetes (T2D). Additionally, differences in gut and oral microbiome composition between participants with a high and low entero-endocrine response were investigated. RESEARCH DESIGN AND METHODS: Ten participants with pre-T2D and ten with T2D underwent three test days with pre-loads consisting of either swallowing water (control), or rinsing with a non-nutritive sweetener solution, or swallowing the sweetener solution before a mixed-meal tolerance test. Blood glucose-dependent insulinotropic polypeptide (GIP), glucagon-like peptide-1 (GLP-1), glucagon, glucose, insulin and peptide YY (PYY) were determined at t = -20, 0, 15, 30, 60, 120 and 240 minutes. The composition of the oral and gut microbiome at baseline were also determined. RESULTS: The entero-endocrine response differed by pre-loads, e.g. a lower PYY response after swallowing the non-nutritive sweetener (-3585.2pg/mL [95% CI: -6440.6; -729.8]; p = 0.01). But it also differed by T2D status, e.g. a higher glucose, glucagon and PYY response was found in participants with T2D, compared to those with pre-T2D. Evidence for associations between the oral and gut microbiome composition and the entero-endocrine response was limited. Still, the level of entero-endocrine response was associated with several oral microbiome measures. Higher oral anterior α-diversity was associated with a lower PYY response (e.g. Inverse Simpson index -1357pg/mL [95% CI -2378; -336; 1.24]), and higher oral posterior α-diversitywith a higher GIP response (e.g. Inverse Simpson index 6773pg/mL [95% CI 132; 13414]) in models adjusted for sex, age and T2D status. CONCLUSIONS: Non-nutritive pre-loads influence the entero-endocrine response to a mixed-meal, and this effect varies based on (pre-)T2D status. The entero-endocrine response is likely not associated with the gut microbiome, and there is limited evidence for association with the α-diversity of the oral microbiome composition. TRIAL REGISTRATION: Trial register: Netherlands Trial Register NTR7212, accessible through International Clinical Trials Registry Platform: ICTRP Search Portal (who.int).

Personalized Dietary Advice to Increase Protein Intake in Older Adults Does Not Affect the Gut Microbiota, Appetite or Central Processing of Food Stimuli in Community-Dwelling Older Adults: A Six-Month Randomized Controlled Trial.

Expert groups argue to raise the recommended daily allowance for protein in older adults from 0.8 to 1.2 g/kg/day to prevent undernutrition. However, protein is thought to increase satiety, possibly through effects on gut microbiota and central appetite regulation. If true, raising daily protein intake may work counterproductively. In a randomized controlled trial, we evaluated the effects of dietary advice aimed at increasing protein intake to 1.2 g/kg adjusted body weight/day (g/kg aBW/day) on appetite and gut microbiota in 90 community-dwelling older adults with habitual protein intake <1.0 g/kg aBW/day (Nintervention = 47, Ncontrol = 43). Food intake was determined by 24-h dietary recalls and gut microbiota by 16S rRNA sequencing. Functional magnetic resonance imaging (fMRI) scans were performed in a subgroup of 48 participants to evaluate central nervous system responses to food-related stimuli. Both groups had mean baseline protein intake of 0.8 ± 0.2 g/kg aBW/day. At 6 months' follow-up this increased to 1.2 ± 0.2 g/kg aBW/day for the intervention group and 0.9 ± 0.2 g/kg aBW/day for the control group. Microbiota composition was not affected, nor were appetite or brain activity in response to food-related stimuli. Increasing protein intake in older adults to 1.2 g/kg aBW/day does not negatively impact the gut microbiota or suppress appetite.

Gut microbial characteristics in poor appetite and undernutrition: a cohort of older adults and microbiota transfer in germ-free mice.

BACKGROUND: Older adults are particularly prone to the development of poor appetite and undernutrition. Possibly, this is partly due to the aged gut microbiota. We aimed to evaluate the gut microbiota in relation to both poor appetite and undernutrition in community-dwelling older adults. Furthermore, we studied the causal effects of the microbiota on body weight and body composition by transferring faecal microbiota from cohort participants into germ-free mice. METHODS: First, we conducted a cross-sectional cohort study of 358 well-phenotyped Dutch community-dwelling older adults from the Longitudinal Aging Study Amsterdam. Data collection included body measurements, a faecal and blood sample, as well as extensive questionnaires on appetite, dietary intake, and nutritional status. Appetite was assessed by the Council of Nutrition Appetite Questionnaire (CNAQ) and undernutrition was defined by either a low body mass index (BMI) (BMI < 20 kg/m2 if <70 years or BMI < 22 kg/m2 if ≥70 years) or >5% body weight loss averaged over the last 2 years. Gut microbiota composition was determined with 16S rRNA sequencing. Next, we transferred faecal microbiota from 12 cohort participants with and without low BMI or recent weight loss into a total of 41 germ-free mice to study the potential causal effects of the gut microbiota on host BMI and body composition. RESULTS: The mean age (range) of our cohort was 73 (65-93); 58.4% was male. Seventy-seven participants were undernourished and 21 participants had poor appetite (CNAQ < 28). A lower abundance of the genus Blautia was associated with undernutrition (log2 fold change = -0.57, Benjamini-Hochberg-adjusted P = 0.008), whereas higher abundances of taxa from Lachnospiraceae, Ruminococcaceae UCG-002, Parabacteroides merdae, and Dorea formicigenerans were associated with poor appetite. Furthermore, participants with poor appetite or undernutrition had reduced levels of faecal acetate (P = 0.006 and 0.026, respectively). Finally, there was a trend for the mice that received faecal microbiota from older adults with low BMI to weigh 1.26 g less after 3 weeks (P = 0.086) and have 6.13% more lean mass (in % body weight, P = 0.067) than the mice that received faecal microbiota from older adults without low BMI or recent weight loss. CONCLUSIONS: This study demonstrates several associations of the gut microbiota with both poor appetite and undernutrition in older adults. Moreover, it is the first to explore a causal relation between the aged gut microbiota and body weight and body composition in the host. Possibly, microbiota-manipulating strategies will benefit older adults prone to undernutrition.

HDHL-INTIMIC: A European Knowledge Platform on Food, Diet, Intestinal Microbiomics, and Human Health.

Studies indicate that the intestinal microbiota influences general metabolic processes in humans, thereby modulating the risk of chronic diseases such as type 2 diabetes, allergy, cardiovascular disease, and colorectal cancer (CRC). Dietary factors are also directly related to chronic disease risk, and they affect the composition and function of the gut microbiota. Still, detailed knowledge on the relation between diet, the microbiota, and chronic disease risk is limited. The overarching aim of the HDHL-INTIMIC (INtesTInal MICrobiomics) knowledge platform is to foster studies on the microbiota, nutrition, and health by assembling available knowledge of the microbiota and of the other aspects (e.g., food science and metabolomics) that are relevant in the context of microbiome research. The goal is to make this information findable, accessible, interoperable, and reusable (FAIR) to the scientific community, and to share information with the various stakeholders. Through these efforts a network of transnational and multidisciplinary collaboration has emerged, which has contributed to further develop and increase the impact of microbiome research in human health. The roles of microbiota in early infancy, during ageing, and in subclinical and clinically manifested disease are identified as urgent areas of research in this knowledge platform.

Vitamin D supplementation in chronic obstructive pulmonary disease patients with low serum vitamin D: a randomized controlled trial.

BACKGROUND: Vitamin D deficiency is frequently found in patients with chronic obstructive pulmonary disease (COPD). Vitamin D has antimicrobial, anti-inflammatory, and immunomodulatory effects. Therefore, supplementation may prevent COPD exacerbations, particularly in deficient patients. OBJECTIVES: We aimed to assess the effect of vitamin D supplementation on exacerbation rate in vitamin D-deficient patients with COPD. METHODS: We performed a multicenter, double-blind, randomized controlled trial. COPD patients with ≥1 exacerbations in the preceding year and a vitamin D deficiency (15-50 nmol/L) were randomly allocated in a 1:1 ratio to receive either 16,800 International Units (IU) vitamin D3 or placebo once a week during 1 y. Primary outcome of the study was exacerbation rate. Secondary outcomes included time to first and second exacerbations, time to first and second hospitalizations, use of antibiotics and corticosteroids, pulmonary function, maximal respiratory mouth pressure, physical performance, skeletal muscle strength, systemic inflammatory markers, nasal microbiota composition, and quality of life. RESULTS: The intention-to-treat population consisted of 155 participants. Mean ± SD serum 25-hydroxyvitamin D [25(OH)D] concentration after 1 y was 112 ± 34 nmol/L in the vitamin D group, compared with 42 ± 17 nmol/L in the placebo group. Vitamin D supplementation did not affect exacerbation rate [incidence rate ratio (IRR): 0.90; 95% CI: 0.67, 1.21]. In a prespecified subgroup analysis in participants with 25(OH)D concentrations of 15-25 nmol/L (n = 31), no effect of vitamin D supplementation was found (IRR: 0.91; 95% CI: 0.43, 1.93). No relevant differences were found between the intervention and placebo groups in terms of secondary outcomes. CONCLUSIONS: Vitamin D supplementation did not reduce exacerbation rate in COPD patients with a vitamin D deficiency.This trial was registered at clinicaltrials.gov as NCT02122627.

T-Cup: A Cheap, Rapid, and Simple Home Device for Isothermal Nucleic Acid Amplification.

During the SARS-CoV2 pandemic, it has become clear that centralized testing suffers from multiple bottlenecks. Logistics, number of machines, and people available to run the diagnostic tests are limited. A solution to those bottlenecks would be a fully decentralized system, where people can test themselves at home and only report back the outcome of the test in a centralized database. Here a noninstrumental device capable of achieving isothermal conditions useful for detecting the SARS-CoV2 RNA using loop mediated amplification (LAMP) tests is presented. This device, compared to others reported in literature or present on the market, is cheap, easy to produce and use, and has little impact on the environment. Using a simple aluminum coffee capsule, a phase change material, and a 3D printed holder, this device, when placed in boiling water, is able to maintain a temperature of 65 °C for 25 min, required for running the LAMP reaction. In principle, this device can be applied to any LAMP reaction, and hence employed for many different applications, and can be deployed in large quantities in short amount of time.

Comparability of microbiota of swabbed and spit saliva.

In general, saliva is used for microbiota analysis in longitudinal studies, and several collection methods are being used. Using a robust sample collection procedure is important, as it may influence salivary composition. This study explored the comparability of the microbiota of swabbed and spit saliva. Twenty-two females participated in this cross-sectional study. The bacterial composition of the three saliva samples (swab collected by the participant (SW-P), swab collected by the researcher (SW-R), and spit (SP) was assessed by 16S rRNA gene amplicon sequencing. The bacterial composition of the swabbed and the spit saliva was significantly different irrespective of the operator, and Shannon diversity was significantly higher in spit saliva than in SW-P and SW-R. The salivary microbiota of spit and swabbed adult saliva differs significantly. Research on microbial composition therefore requires collection of similar saliva sample types in all study participants.

Associations of the oral microbiota and Candida with taste, smell, appetite and undernutrition in older adults.

Poor taste and smell function are widely thought to contribute to the development of poor appetite and undernutrition in older adults. It has been hypothesized that the oral microbiota play a role as well, but evidence is scarce. In a cross-sectional cohort of 356 older adults, we performed taste and smell tests, collected anthropometric measurements and tongue swabs for analysis of microbial composition (16S rRNA sequencing) and Candida albicans abundance (qPCR). Older age, edentation, poor smell and poor appetite were associated with lower alpha diversity and explained a significant amount of beta diversity. Moreover, a lower Streptococcus salivarius abundance was associated with poor smell identification score, whereas high C. albicans abundance seemed to be associated with poor smell discrimination score. In our population, neither the tongue microbiota, nor C. albicans were associated with poor taste or directly with undernutrition. Our findings do suggest a host-microbe interaction with regard to smell perception and appetite.

SCOPE enables type III CRISPR-Cas diagnostics using flexible targeting and stringent CARF ribonuclease activation.

Characteristic properties of type III CRISPR-Cas systems include recognition of target RNA and the subsequent induction of a multifaceted immune response. This involves sequence-specific cleavage of the target RNA and production of cyclic oligoadenylate (cOA) molecules. Here we report that an exposed seed region at the 3' end of the crRNA is essential for target RNA binding and cleavage, whereas cOA production requires base pairing at the 5' end of the crRNA. Moreover, we uncover that the variation in the size and composition of type III complexes within a single host results in variable seed regions. This may prevent escape by invading genetic elements, while controlling cOA production tightly to prevent unnecessary damage to the host. Lastly, we use these findings to develop a new diagnostic tool, SCOPE, for the specific detection of SARS-CoV-2 from human nasal swab samples, revealing sensitivities in the atto-molar range.

Poor Taste and Smell Are Associated with Poor Appetite, Macronutrient Intake, and Dietary Quality but Not with Undernutrition in Older Adults.

BACKGROUND: Age-related declines in taste and smell function are widely assumed to contribute to the decrease in appetite and the development of undernutrition in older adults. OBJECTIVES: Here we aim to assess the associations of both taste and smell function with several nutrition-related outcomes in a single study, with poor appetite and undernutrition as primary outcomes. METHODS: This is a cross-sectional cohort study of 359 community-dwelling Dutch older adults, aged 65-93 y. Taste function was measured for all 5 basic tastes. Smell function was assessed with 3 tests: for odor identification, discrimination, and threshold. Self-reported taste and smell, appetite, energy (kcal/d) and macronutrient (% energy) intake, and covariates were assessed with extensive questionnaires. Dietary quality was calculated using the Dutch Healthy Diet index 2015, Alternative Healthy Eating Index 2010, and Mediterranean Diet Score. Body measurements included body weight (current and 2 y prior), height, and body impedance analysis. Data were analyzed via multiple logistic and linear regression. RESULTS: Of our sample, 9.2% had poor taste and 17.0% poor smell, 6.1% had poor appetite, and 21.4% were undernourished. Self-reported poor taste (OR: 8.44; 95% CI: 1.56, 45.56; P = 0.013) was associated with poor appetite, but no other taste or smell score was associated with either poor appetite or undernutrition. Some associations were found of individual taste and smell scores with macronutrient intake and dietary quality. Self-reported poor taste and smell were both consistently associated with poorer dietary quality. CONCLUSIONS: In community-dwelling older adults, specific taste and smell impairments may have diverse consequences for appetite, food intake, or dietary quality. However, this does not necessarily result in undernutrition. The consistent associations of self-reported poor taste and smell with poor dietary quality do underline the usefulness of this information when screening for nutritional risk.

Dentistry and OMICS: Transcriptome Dynamics of an Oral Ecosystem as Measured by Changes in Oral Polymorphonuclear Neutrophils in Experimental Gingivitis.

Oral health and dentistry are essential components of systems medicine, which has received lesser attention in comparison to other medical fields, such as cancer biology. In this context, oral polymorphonuclear neutrophils (oPMNs) play an important role in the maintenance of oral health. To the best of our knowledge, this is the first study to report original observations on the transcriptional responses of oPMNs during experimentally induced gingivitis, by temporarily refraining from regular oral care. Oral rinses were prospectively collected at four different time points for oPMNs isolation from healthy volunteers: day 1 (start of the experimental gingivitis challenge), day 9 (during challenge), day 14 (end of the challenge), and day 21 (postchallenge). Transcriptome of oPMNs was determined by RNA sequencing. Differentially expressed genes (DEGs) were selected at p < 0.01 level, and evaluated for pathway regulation using Ingenuity Pathway Analysis suite. We found four major clusters of DEGs, consisting of 256 initial response DEGs (day 9 only), 221 late response DEGs (day 14 only), 53 persistent responsive DEGs (consistent at day 9 and 14), and 524 DEGs showing responses only in the postchallenge phase (day 21 only). Pathway analysis of the initial and late response DEGs showed involvement in many immune regulatory pathways and PMN function, whereas DEGs at day 21 were associated with epithelial adherence signaling and other miscellaneous related signaling pathways. The results from this pilot study showed that oPMNs mediate oral inflammatory processes, suggesting their immunomodulatory role in oral equilibrium.

Development of the gut microbiota in early life: The impact of cystic fibrosis and antibiotic treatment.

OBJECTIVES: Patients with Cystic Fibrosis (CF) suffer from pancreatic insufficiency, lipid malabsorption and gastrointestinal complaints, next to progressive pulmonary disease. Altered mucosal homoeostasis due to malfunctioning chloride channels results in an adapted microbial composition of the gastrointestinal and the respiratory tract. Additionally, antibiotic treatment has the potential to distort resident microbial communities dramatically. This study aims to investigate early life development of the gut microbial community composition of children with CF compared to healthy infants and to study the independent effects of antibiotics taking into account other clinical and lifestyle factors. STUDY DESIGN: Faecal samples from 20 infants with CF and 45 healthy infants were collected regularly during the first 18 months of life and microbial composition was determined using 16S rRNA based sequencing. RESULTS: We observed significant differences in the overall microbiota composition between infants with CF and healthy infants (p<0.001). Akkermansia and Anaerostipes were significantly more abundant in control infants, whereas Streptococci and E. coli were significantly more abundant in infants with CF, also after correction for several clinical factors (p<0.05). Antibiotic use in infants with CF was associated with a lower alpha diversity, a reduced abundance of Bifidobacterium and Bacteroides, and a higher abundance of Enterococcus. CONCLUSION: Microbial development of the gut is different in infants with CF compared to healthy infants from the first months of life on, and further deviates over time, in part as a result of antibiotic treatment. The resulting dysbiosis may have significant functional consequences for the microbial ecosystem in CF patients.

A salivary metabolite signature that reflects gingival host-microbe interactions: instability predicts gingivitis susceptibility.

Several proteins and peptides in saliva were shown to stimulate gingival wound repair, but the role of salivary metabolites in this process remains unexplored. In vitro gingival re-epithelialization kinetics were determined using unstimulated saliva samples from healthy individuals collected during an experimental gingivitis study. Elastic net regression with stability selection identified a specific metabolite signature in a training dataset that was associated with the observed re-epithelialization kinetics and enabled its prediction for all saliva samples obtained in the clinical study. This signature encompassed ten metabolites, including plasmalogens, diacylglycerol and amino acid derivatives, which reflect enhanced host-microbe interactions. This association is in agreement with the positive correlation of the metabolite signature with the individual's gingival bleeding index. Remarkably, intra-individual signature-variation over time was associated with elevated risk for gingivitis development. Unravelling how these metabolites stimulate wound repair could provide novel avenues towards therapeutic approaches in patients with impaired wound healing capacity.

Association of oral health with body weight: a prospective study in community-dwelling older adults.

BACKGROUND: To prevent involuntary weight loss in older people, the knowledge about factors affecting body weight (BW) is essential. Therefore, we aimed to investigate the longitudinal associations of multiple oral health aspects with BW in community-dwelling older adults. METHODS: This analysis is based on prospective data with a 10-year follow-up of 657 Dutch community-dwelling older adults (age 66.4 ± 5.8 years, 54% female) from the Longitudinal Aging Study Amsterdam. Participants' characteristics, BW, and 12 oral health variables (teeth, dentures, nine oral problems, self-rated oral health) were assessed in 2005/07 and 2015/16. The association between oral health and BW was analyzed by mixed models and adjusted for demographic, socio-economic, smoking, health, and functional aspects considering data of both assessments. RESULTS: Mean BW was 79.1 ± 13.3 kg at baseline (B) and 77.6 ± 13.8 kg at follow-up (FU). At baseline, 29.6% of the participants reported being edentulous (FU:34.4%) and 55.8% to wear dentures (FU:62.3%). Dental pain while chewing was the oral problem with the lowest (B:5.2%, FU:6.6%) and xerostomia with the highest prevalence at both examinations (B:24.3%, FU:30.0%). Most participants rated their oral status as healthy (B:65.2%, FU:66.9%). Neither edentulism and denture use nor oral problems showed a longitudinal association with BW. In contrast, self-rated oral health was associated with BW (b = 0.724, SE = 0.296, p = 0.015) after adjusting for multiple confounders. CONCLUSIONS: In community-dwelling older adults self-rated oral health may indicate changes in body weight in the long term. Therefore, this simple measure could serve to identify a risk for weight loss and to initiate oral interventions in clinical practice.

Oral health determinants of incident malnutrition in community-dwelling older adults.

OBJECTIVE: Poor oral health might be a modifiable determinant of malnutrition in older age. We aimed to investigate the associations of multiple oral health characteristics with incident malnutrition in community-dwelling older adults. METHODS: This exploratory analysis is based on prospective data from 893 participants, aged 55-80 years without malnutrition in 2005/06 from the Longitudinal Aging Study Amsterdam. In 2007, 19 oral health characteristics from the domains teeth/dentures, oral hygiene, oral problems, and self-rated oral health were assessed by questionnaire. Incident malnutrition was defined as presence of low body mass index (<20 kg/m² in people <70 years, <22 kg/m² ≥70 years) and/or self-reported involuntary weight loss ≥5% in previous 6 months at any of the follow-ups (2008/09, 2012/13, 2015/16). Associations of oral aspects with incident malnutrition were analyzed by cox proportional hazard models and adjusted for confounders. RESULTS: The 9-year incidence of malnutrition was 13.5%. Sixteen of 19 oral health aspects were not associated with incident malnutrition in the crude models. Adjusted hazard ratios for incident malnutrition were 2.14 (1.10-4.19, p = 0.026) for toothache while chewing, 2.10 (0.88-4.98, p = 0.094) for an unhealthy oral health status, and 1.99 (0.93-4.28, p = 0.077) for xerostomia in edentulous participants, however, the two latter ones failing to reach statistical significance. CONCLUSIONS: We identified toothache while chewing as determinant of incident malnutrition in community-dwelling older adults, and found indications that poor oral health and xerostomia in combination with having no teeth may play a role in developing malnutrition. However, these outlined tendencies need to be proven in further studies. CLINICAL SIGNIFICANCE: Regarding the development of strategies to prevent malnutrition in older people toothache while chewing, xerostomia, and self-rated oral health would be of specific interest as these factors are modifiable and can be easily assessed by self-reports.

Loss of Microbial Topography between Oral and Nasopharyngeal Microbiota and Development of Respiratory Infections Early in Life.

Rationale: The respiratory microbiota is increasingly being appreciated as an important mediator in the susceptibility to childhood respiratory tract infections (RTIs). Pathogens are presumed to originate from the nasopharyngeal ecosystem.Objectives: To investigate the association between early life respiratory microbiota and development of childhood RTIs.Methods: In a prospective birth cohort (Microbiome Utrecht Infant Study: MUIS), we characterized the oral microbiota longitudinally from birth until 6 months of age of 112 infants (nine regular samples/subject) and compared them with nasopharyngeal microbiota using 16S-rRNA-based sequencing. We also characterized oral and nasopharynx samples during RTI episodes in the first half year of life.Measurements and Main Results: Oral microbiota were driven mostly by feeding type, followed by age, mode of delivery, and season of sampling. In contrast to our previously published associations between nasopharyngeal microbiota development and susceptibility to RTIs, oral microbiota development was not directly associated with susceptibility to RTI development. However, we did observe an influx of oral taxa, such as Neisseria lactamica, Streptococcus, Prevotella nanceiensis, Fusobacterium, and Janthinobacterium lividum, in the nasopharyngeal microbiota before and during RTIs, which was accompanied by reduced presence and abundance of Corynebacterium, Dolosigranulum, and Moraxella spp. Moreover, this phenomenon was accompanied by reduced niche differentiation indicating loss of ecological topography preceding confirmed RTIs. This loss of ecological topography was further augmented by start of daycare, and linked to consecutive development of symptomatic infections.Conclusions: Together, our results link the loss of topography to subsequent development of RTI episodes. This may lead to new insights for prevention of RTIs and antibiotic use in childhood.

Dose-dependent impact of oxytetracycline on the veal calf microbiome and resistome.

BACKGROUND: Antibiotic therapy is commonly used in animal agriculture. Antibiotics excreted by the animals can contaminate farming environments, resulting in long term exposure of animals to sub-inhibitory levels of antibiotics. Little is known on the effect of this exposure on antibiotic resistance. In this study, we aimed to investigate the long term effects of sub-inhibitory levels of antibiotics on the gut microbiota composition and resistome of veal calves in vivo. Forty-two veal calves were randomly assigned to three groups. The first group (OTC-high) received therapeutic oral dosages of 1 g oxytetracycline (OTC), twice per day, during 5 days. The second group (OTC-low) received an oral dose of OTC of 100-200 µg per day during 7 weeks, mimicking animal exposure to environmental contamination. The third group (CTR) did not receive OTC, serving as unexposed control. Antibiotic residue levels were determined over time. The temporal effects on the gut microbiota and antibiotic resistance gene abundance was analysed by metagenomic sequencing. RESULTS: In the therapeutic group, OTC levels exceeded MIC values. The low group remained at sub-inhibitory levels. The control group did not reach any significant OTC levels. 16S rRNA gene-based analysis revealed significant changes in the calf gut microbiota. Time-related changes accounted for most of the variation in the sequence data. Therapeutic application of OTC had transient effect, significantly impacting gut microbiota composition between day 0 and day 2. By metagenomic sequence analysis we identified six antibiotic resistance genes representing three gene classes (tetM, floR and mel) that differed in relative abundance between any of the intervention groups and the control. qPCR was used to validate observations made by metagenomic sequencing, revealing a peak of tetM abundance at day 28-35 in the OTC-high group. No increase in resistance genes abundance was seen in the OTC-low group. CONCLUSIONS: Under the conditions tested, sub-therapeutic administration of OTC did not result in increased tetM resistance levels as observed in the therapeutic group.

Contribution of Host Defence Proteins and Peptides to Host-Microbiota Interactions in Chronic Inflammatory Lung Diseases.

The respiratory tract harbours a variety of microorganisms, collectively called the respiratory microbiota. Over the past few years, alterations in respiratory and gut microbiota composition have been associated with chronic inflammatory diseases of the lungs. How these changes influence disease development and progression is an active field of investigation. Identifying and understanding host-microbiota interactions and factors contributing to these interactions could promote the development of novel therapeutic strategies aimed at restoring host-microbiota homeostasis. In this review, we discuss recent literature on host-microbiota interactions in the respiratory tract, with a specific focus on the influence of endogenous host defence peptides and proteins (HDPs) on the composition of microbiota populations in vivo and explore possible HDPs-related therapeutic approaches targeting microbiota dysbiosis in chronic inflammatory lung diseases.

The Impact of Maltitol-Sweetened Chewing Gum on the Dental Plaque Biofilm Microbiota Composition.

Background: The oral cavity harbors a complex microbial ecosystem, intimately related to oral health and disease. The use of polyol-sweetened gum is believed to benefit oral health through stimulation of salivary flow and impacting oral pathogenic bacteria. Maltitol is often used as sweetener in food products. This study aimed to establish the in vivo effects of frequent consumption of maltitol-sweetened chewing gum on the dental plaque microbiota in healthy volunteers and to establish the cellular and molecular effects by in vitro cultivation and transcriptional analysis. Results: An intervention study was performed in 153 volunteers, randomly assigned to three groups (www.trialregister.nl; NTR4165). One group was requested to use maltitol gum five times daily, one group used gum-base, and the third group did not use chewing gum. At day 0 and day 28, 24 h-accumulated supragingival plaque was collected at the lingual sites of the lower jaw and the buccal sites of the upper jaw and analyzed by 16S ribosomal rRNA gene sequencing. At day 42, 2 weeks after completion of the study, lower-jaw samples were collected and analyzed. The upper buccal plaque microbiota composition had lower bacterial levels and higher relative abundances of (facultative) aerobic species compared to the lower lingual sites. There was no difference in bacterial community structure between any of the three study groups (PERMANOVA). Significant lower abundance of several bacterial phylotypes was found in maltitol gum group compared to the gum-base group, including Actinomyces massiliensis HOT 852 and Lautropia mirabilis HOT 022. Cultivation studies confirmed growth inhibition of A. massiliensis and A. johnsonii by maltitol at levels of 1% and higher. Transcriptome analysis of A. massiliensis revealed that exposure to maltitol resulted in changes in the expression of genes linked to osmoregulation, biofilm formation, and central carbon metabolism. Conclusion: The results showed that chewing itself only marginally impacted the plaque microbiota composition. Use of maltitol-sweetened gum lowered abundance of several bacterial species. Importantly, the species impacted play a key role in the early formation of dental biofilms. Further studies are required to establish if frequent use of maltitol gum impacts early dental-plaque biofilm development.