Impact of lifestyle on the human gut microbiome in health and disease

Abstract. The human body’s most metabolically significant microbial community is the gut microbiome. The diversity and composition of the gut microbiome determine the available metabolic pathways. Microbially derived metabolites, especially short-chain fatty acids and secondary bile acids, impact the host’s physiology, promoting or impairing health and performance. Changes in the gut microbiome are associated with the prevalence of many diseases, including cardiovascular diseases, metabolic disorders, and obesity. Lifestyle factors have been found to have a significant impact on the composition of the gut microbiome and its metabolic activity. Diet significantly affects the composition of the gut microbiome, and changes in diet can rapidly alter its composition. Fiber is a key component of the diet that maintains a diverse and healthy microbiome. The Western diet, characterized by low fiber intake and high fat and protein content, is associated with the development of various metabolic and cardiovascular diseases. Exercise, especially aerobic endurance training, regulates the composition and function of the gut microbiome. An active lifestyle and a balanced diet are associated with a health-promoting gut microbiome. A healthy gut microbiome can regulate host physiology through metabolic products, preventing the onset of diseases or mitigating their progression. The gut microbiome also has implications for the host’s physical performance and can provide significant benefit for those working in demanding conditions or engaging in regular physical activity. Microbially derived short-chain fatty acid propionate increases the host’s maximal oxygen uptake and improves running performance. Well-performing soldiers and athletes have been found to have a gut microbiome that is supportive in meeting the demands of physical exertion and increased energy requirements. The significance of the gut microbiome for host health is widely acknowledged and supported. The ability of lifestyle factors to regulate the composition and function of the gut microbiome offers interesting possibilities for the prevention and treatment of common cardiovascular and metabolic diseases.Elämäntapojen vaikutus ihmisen suolistomikrobiomiin. Tiivistelmä. Ihmisen aineenvaihdunnallisesti merkittävin mikrobiyhteisö on suolistomikrobiomi. Suolistomikrobiomin lajirikkaus ja koostumus määrittävät käytettävissä olevat aineenvaihdunnan reitit. Mikrobiperäiset aineenvaihduntatuotteet—erityisesti lyhytketjuiset rasvahapot ja sekundaariset sappihapot—vaikuttavat isännän fysiologiaan edistäen tai heikentäen terveyttä ja suorituskykyä. Moniin länsimaissa yleistyviin sydän- ja verisuonitauteihin, sekä aineenvaihduntasairauksiin ja liikalihavuuteen, liittyy muutoksia suolistomikrobiomissa. Elämäntavoilla on todettu olevan suuri vaikutus suolistomikrobiomin koostumukseen ja aineenvaihdunnan aktiivisuuteen. Ruokavalio vaikuttaa merkittävästi suolistomikrobiomin koostumukseen ja muutokset ruokavaliossa voivat nopeasti muuttaa suolistomikrobiomin koostumusta. Kuitu on tärkeä ruokavalion osatekijä, joka ylläpitää lajirikasta ja terveellistä mikrobiomia. Länsimainen ruokavalio, jolle on tyypillistä matala kuidun saanti sekä korkea rasvan ja proteiinin pitoisuus, liittyy monien aineenvaihdunta-, sydän- ja verisuonitautien kehittymiseen. Toisaalta liikunta, erityisesti kestävyysharjoittelu, säätelee suolistomikrobiomin koostumusta ja toimintaa. Aktiivinen elämäntapa ja tasapainoinen ruokavalio yhdistetään terveyttä edistävään ja ylläpitävään suolistomikrobiomiin. Terve suolistomikrobiomi pystyy aineenvaihdunnantuotteiden kautta säätelemään isännän fysiologiaa ja ennaltaehkäisemään tautien syntyä tai hillitsemään niiden etenemistä. Suolistomikrobiomilla on vaikutuksia myös isännän fyysiseen suorituskykyyn ja voi tarjota merkittävää tukea vaativissa olosuhteissa työskenteleville tai aktiivisesti liikkuville. Mikrobiperäinen lyhytketjuinen rasvahappo propionaatti lisää isännän maksimaalista hapenottokykyä ja parantaa juoksusuoritusta. Hyvin suoriutuvilla sotilailla ja urheilijoilla on havaittu olevan suolistomikrobiomi, joka on otollinen vastaamaan fyysisen rasituksen ja kohonneen energiantarpeen vaatimuksiin. Suolistomikrobiomin merkitys isännän terveyteen on laajasti todettu ja tuettu. Elämäntapojen kyky säädellä suolistomikrobiomin koostumusta ja toimintaa tarjoaa mielenkiintoisia mahdollisuuksia yleisten sydän-, verisuoni- ja aineenvaihduntatautien ennaltaehkäisyyn ja hoitoon

Comparable response of wild rodent gut microbiome to anthropogenic habitat contamination

Abstract Species identity is thought to dominate over environment in shaping wild rodent gut microbiota, but it remains unknown whether the responses of host gut microbiota to shared anthropogenic habitat impacts are species-specific or if the general gut microbiota response is similar across host species. Here, we compare the influence of exposure to radionuclide contamination on the gut microbiota of four wild mouse species: Apodemus flavicollis, A. sylvaticus, A. speciosus and A. argenteus. Building on the evidence that radiation impacts bank vole (Myodes glareolus) gut microbiota, we hypothesized that radiation exposure has a general impact on rodent gut microbiota. Because we sampled (n = 288) two species pairs of Apodemus mice that occur in sympatry in habitats affected by the Chernobyl and Fukushima nuclear accidents, these comparisons provide an opportunity for a general assessment of the effects of exposure to environmental contamination (radionuclides) on gut microbiota across host phylogeny and geographical areas. In general agreement with our hypothesis, analyses of bacterial 16S rRNA gene sequences revealed that radiation exposure alters the gut microbiota composition and structure in three of the four species of Apodemus mice. The notable lack of an association between the gut microbiota and soil radionuclide contamination in one mouse species from Fukushima (A. argenteus) probably reflects host “radiation escape” through its unique tree-dwelling lifestyle. The finding that host ecology can modulate effects of radiation exposure offers an interesting counterpoint for future analyses into effects of radiation or any other toxic exposure on host and its associated microbiota. Our data show that exposure to radionuclide contamination is linked to comparable gut microbiota responses across multiple species of rodents

Compensatory IgM to the rescue:patients with selective IgA deficiency have increased natural IgM antibodies to MAA–LDL and no changes in oral microbiota

Abstract IgA is the most abundant Ab in the human body. However, most patients with selective IgA deficiency (SIgAD) are asymptomatic. IgM, and to lesser extent IgG Abs, are generally presumed to compensate for the lack of IgA in SIgAD by multiplying and adopting functions of IgA. We used data from the Northern Finland Birth Cohort 1966 to investigate whether SIgAD patients have differences in levels of natural Abs to oxidized epitopes compared with 20 randomly selected healthy controls. First, we screened the saliva and serum samples from the Northern Finland Birth Cohort 1966 cohort (n = 1610) for IgA concentration. We detected five IgA-deficient subjects, yielding a prevalence of 0.3%, which is consistent with the general prevalence of 0.25% in the Finnish population. To detect natural Abs, we used malondialdehyde acetaldehyde–low-density lipoprotein (MAA–LDL), an Ag known to bind natural Abs. In this study, we show that natural secretory IgM and IgG Abs to MAA–DL were significantly increased in subjects with SIgAD. Given that secretory IgA is an important part of mucosal immune defense and that, in the gut microbiota, dysbiosis with SIgAD patients has been observed, we characterized the oral bacterial microbiota of the subjects with and without SIgAD using high-throughput 16S rRNA gene sequencing. We found no significant alterations in diversity and composition of the oral microbiota in subjects with SIgAD. Our data suggest that increased levels of secretory natural Abs in patients with SIgAD could be a compensatory mechanism, providing alternative first-line defense against infections and adjusting mucosal milieu to maintain a healthy oral microbiota

Urban forest soils harbour distinct and more diverse communities of bacteria and fungi compared to less disturbed forest soils

Anthropogenic changes to land use drive concomitant changes in biodiversity, including that of the soil microbiota. However, it is not clear how increasing intensity of human disturbance is reflected in the soil microbial communities. To address this issue, we used amplicon sequencing to quantify the microbiota (bacteria and fungi) in the soil of forests (n=312) experiencing four different land uses, national parks (set aside for nature conservation), managed (for forestry purposes), suburban (on the border of an urban area) and urban (fully within a town or city), which broadly represent a gradient of anthropogenic disturbance. Alpha diversity of bacteria and fungi increased with increasing levels of anthropogenic disturbance, and was thus highest in urban forest soils and lowest in the national parks. The forest soil microbial communities were structured according to the level of anthropogenic disturbance, with a clear urban signature evident in both bacteria and fungi. Despite notable differences in community composition, there was little change in the predicted functional traits of urban bacteria. By contrast, urban soils exhibited a marked loss of ectomycorrhizal fungi. Soil pH was positively correlated with the level of disturbance, and thus was the strongest predictor of variation in alpha and beta diversity of forest soil communities, indicating a role of soil alkalinity in structuring urban soil microbial communities. Hence, our study shows how the properties of urban forest soils promote an increase in microbial diversity and a change in forest soil microbiota composition.peerReviewe