27Background. 28The anterior nares host a complex microbial community that contributes to upper airway health. 29Although the bacterial composition of the nasal passages have been well characterized in 30 healthy and diseased cohorts, the role of prolonged environmental exposures and exercise in 31 shaping the nasal microbiome in healthy adults is poorly understood. In this study, we 32 longitudinally sampled female collegiate Division I athletes from two teams experiencing a 33 similar athletic season and exercise regimen but vastly different environmental exposures 34 (Swim/Dive and Basketball). Using 16S rRNA gene sequencing, we evaluated the longitudinal 35 dynamics of the nasal microbiome pre-, during-, and at the end of the athletic season. 36 Results. 37The nasal microbiota of the Swim/Dive and Basketball teams were distinct from each other at 38 each time point sampled, driven by either low abundance (Jaccard, PERMANOVA p<0.05) or 39 high-abundance changes in composition (Bray-Curtis, PERMANOVA p<0.05). The rate of 40 change of microbial communities were greater in the Swim/Dive team compared to the 41 Basketball team characterized by an increase in Staphylococcus in Swim/Dive and a decrease 42 in Corynebacterium in both teams over time. 43 Conclusions. 44This is the first study that has evaluated the nasal microbiome in athletes. We obtained 45 longitudinal nasal swabs from two gender-matched teams with similar age distributions (18-22 46 years old) over a 6 month period. Differences in the microbiota between teams and over time 47 indicate that chlorine exposure, and potentially athletic training, induced changes in the nasal 48 microbiome. 49 50 51 52

Recent studies have demonstrated alterations in the gut microbiota composition in mice modeling Alzheimer’s disease (AD) pathologies; however, these studies have only included up to 4 time points. Our study is the first of its kind to characterize the gut microbiota of a transgenic AD mouse model, fortnightly, from 4 weeks of age to 52 weeks of age, to quantify the temporal dynamics in the microbial composition that correlate with the development of disease pathologies and host immune gene expression.

BackgroundThe gut microbiota, the aggregates of all microbial cells that inhabit the gut, bidirectionally communicates with the brain through cytokines, hormones, metabolites, and neurotransmitters via the gut microbiota‐brain axis. The gut microbiota is thought to contribute to the development of Alzheimer’s disease (AD), which is characterized by plaque deposition, neurofibrillary tangles, and neuroinflammation. We hypothesize that manipulation of the gut microbiota will alter development of AD pathologies and neuroinflammation via the gut microbiota‐brain axis.MethodWe performed fecal microbiota transplants (FMT) from aged (52‐64 weeks) 3xTg‐AD mice, which are modeling plaques and neurofibrillary tangles, to young 3xTg‐AD (n=5) or wild‐type mice (n=10) via oral gavage. Phosphate buffered saline (PBS) was gavaged into 3xTg‐AD (n=5) and wild‐type mice (n=10) as a control. At 8 weeks, mice were gavaged with FMT or PBS for 5 consecutive days, followed by fortnightly maintenance transplants for 24 weeks. The V4 region of the 16S rRNA gene was sequenced on the Illumina MiSeq. Data were analyzed using QIIME 2. Reverse transcriptase qPCR was used to assess microgliosis, astrocytosis, and Th1/Th2 inflammation in the hippocampus of the FMT cohort at 24 weeks of age.ResultWe observed a shift in microbiota composition of FMT‐treated mice when compared to control (PBS‐treated) mice. Bacteroides acidifaciens was increased in 3xTg‐AD and wild‐type mice receiving FMT. We demonstrate partial engraftment of the gut microbiota from aged 3xTg‐AD mice in all FMT‐treated mice, demonstrated by a Random Forest model, which correctly predicts treatment groups based on gut microbiota composition (Accuracy Ratio over baseline assignment: 2.6).ConclusionWe demonstrate the ability to transplant an aged gut microbiome into young mice. Future shallow shotgun metagenomic sequencing will be used to determine the species‐ and strains‐ that engraft in the GI tract. Additionally, targeted reverse transcription RT‐qPCR and immunostaining for plaques and hyperphosphorylated tau in the hippocampus will be used to assess how FMTs alter AD pathologies. These studies will contribute to our understanding of how features of the gut microbiota may contribute to AD development.

BackgroundThe gut microbiota, the aggregates of microbial cells that inhabit the gastrointestinal tract, communicates bidirectionally with the brain via immune, neural, metabolic, and endocrine pathways, known as the gut‐brain axis. The gut‐brain axis is suspected to contribute to the development of Alzheimer’s disease (AD). We hypothesize that altered gut microbiota composition contributes to the development of AD pathologies and neuroinflammation via the gut‐brain axis.MethodTo characterize the gut microbiota of 3xTg‐AD mice modeling plaque deposition and hyperphosphorylated tau, fecal samples were collected fortnightly from 4 to 52 weeks of age (n=57 3xTg‐AD mice, n=31 wild‐type). The V4 region of the 16S rRNA gene was amplified and sequenced on the Illumina MiSeq. Data were analyzed using QIIME 2. Targeted reverse transcription qPCR assays were used to assess inflammation in the hippocampus and colon at 8, 24, and 52 weeks of age. Fold change was calculated using ΔΔCt.ResultOur results show altered microbial communities in 3xTg‐AD mice when compared to wild‐type [(PERMANOVA (8 weeks, p=0.001), (24 weeks, p=0.039), (52 weeks, p=0.058)]. Using q2‐longitudinal, we identified a temporal increase in Bacteroides acidifaciens and Turicibacter spp. in 3xTg‐AD mice (r‐squared = 0.658615). Using Random Forest, we successfully predicted strain in 3xTg‐AD mice 100% of the time, and in WT mice 92.85% of the time, improving accuracy over baseline assignment by 1.3 fold. Colonic expression of GFAP was increased at 24 week 3xTg‐AD mice compared to 52 week 3xTg‐AD mice (p=0.009, Mann‐Whitney). Colonic gene expression of IL‐6 was increased in 52 week 3xTg‐AD mice compared to 52 week WT mice (p=0.015, Mann‐Whitney). Hippocampal expression of GFAP was increased at 52 week 3xTg‐AD mice compared to 52 week WT (p=0.049, Mann‐Whitney). Finally, hippocampal expression of Mrc1 was elevated at 24 weeks in 3xTg‐AD mice compared to 52 weeks (p= 0.004, Mann‐Whitney).ConclusionWe have identified changes in the gut microbiota and immune response that may be predictive of the development of AD pathologies. Future shallow shotgun metagenomics sequencing will assess strain‐level features and functions of the gut microbiota in AD.

The gut microbiota-brain axis is suspected to contribute to the development of Alzheimer’s Disease (AD), a neurodegenerative disease characterized by amyloid-β plaque deposition, neurofibrillary tangles, and neuroinflammation. To evaluate the role of the gut microbiota-brain axis in AD, we characterized the gut microbiota of 3xTg-AD mice modeling amyloidosis and tauopathy and wild type (WT) genetic controls. Fecal samples were collected fortnightly from 4 to 52 weeks, and the V4 region of the 16S rRNA gene was amplified and sequenced on an Illumina MiSeq. RNA was extracted from the colon and hippocampus, converted to cDNA, and used to measure immune gene expression using RT-qPCR. Diversity metrics were calculated using QIIME 2, and a Random Forest classifier was applied to predict bacterial features that are important in predicting mouse genotype. Gut microbiota were compositionally distinct early in life between 3xTg-AD mice and WT mice (PERMANOVA 8 weeks, p = 0.001, 24 weeks, p = 0.039, and 52 weeks, p = 0.058). We demonstrate that mouse genotype was correctly predicted 90–100% using fecal microbiome composition. Finally, we demonstrate that Bacteroides species relative abundance increased over time in 3xTg-AD mice. Taken together, we demonstrate that changes bacterial gut microbiota composition at pre-pathology timepoints are predictive of development of AD pathologies.