Fig. 1. Gut microbiota profile of Asian children. The pie chart represents composition of dominant bacterial families averaged by city. (J. Nakayama et al., Sci. Rep. 2015. DOI: 10.1038/srep08397)
In the Phase I focused on school-aged children aged 7 to 10 years old, we characterized the bacterial community in fecal samples obtained from 303 school-age children living in 10 cities in China, Japan, Taiwan, Thailand, and Indonesia (Fig. 1). These microbiotas were classified into two enterotype-like clusters, each defined by high abundance of either Prevotella (P-type) or Bifidobacterium/Bacteroides (BB-type) (Fig. 2). Majority of children in China, Japan, and Taiwan harbored BB-type, whereas those from Indonesia and Khon Kaen in Thailand mainly harbored P-type. Bangkok was a mixture of BB-type and P-type (Fig. 3). This discrepancy may reflect differences in dietary habits among these countries.
Fig. 2. Principal component analysis and clustering of gut microbiota profiles of 303 Asian children. (J. Nakayama et al., Sci. Rep. 2015. DOI: 10.1038/srep08397) Fig. 3. Distribution of enterotypes among Asian children. (J. Nakayama et al., Sci. Rep. 2015. DOI: 10.1038/srep08397)
OUTCOMES (Phase III)
Impact of Westernized diets on Asian gut microbiota !
The impact of changes in dietary habit on Asian children was found in an island of Philippines. The Phase III study on school-aged children on Leyte island in Philippines characterized the gut microbiota of urban and rural children in the island. Urban children who ate urbanized diets carried Bacteroides-type gut microbiota while rural children who maintained traditional dietary habit carried Prevotella-type gut microbiota (Fig. 4).
A cross-sectional study for Thai children also showed the impact of modern diets on gut microbiota. As shown in Fig. 5, Bangkok children had less short chain fatty acids that is one of important gut bacterial metabolites required for maintenance of host metabolic and immune homeostasis, while children in rural city, Burirum, were rich in short and middle chain fatty acids in the intestine.
The data thus far gained by AMP suggests that gut microbiota of Asian is now being altered by the modernization of dietary habits and that we should carefully monitor the impact of altered microbiota on the health of Asian people. To achieve this objective, AMP has begun Phase IV study focusing on the linkage among modernized diets, gut microbiota, and life-style diseases.
Fig. 4. Redundancy analysis of principal coordinates (CAP) for the correlation between macronutrient intake and fecal bacterial composition of school-age children living in urban city (Ormoc) and rural city (Baybay). (J. Nakayama et al., Front. Microbiol. 2017. doi: 10.3389/fmicb.2017.00197)
Fig. 5. Heat map showing the abundance of each metabolite in samples from Bangkok children (red letter codes) and Burirum children (green letter codes). MT1 group mostly consisting of Burirum children showed high abundance of short and middle chain fatty acids, while MT2 consisting of Bangkok children showed high abundance of amino acids instead of short chain fatty acids. (J. Kisuse et al., Front. Microbiol. 2018. doi: 10.3389/fmicb.2018.01345)
OUTCOMES (Phase IV)
How does gut microbiota link with homeostasis of Asians ?
The changing microbiota under the dietary modernization also affect the health of Asian people. Notably, alteration of structure and function of gut microbiota should have great influence on host energy and immune homeostasis that link with lifestyle diseases. To address this notion, we perform Phase IV study in AMP.
In a cross-sectional study in Yogjakarta in Indonesia, we found anormal microbiota and metabolic profile in obese and T2D subjects (Fig. 6 and 7). Notably, we suspected that B. fragilis plays a key role in the control of fasting blood glucose (FBG) via deconjugation of conjugated bile acids functioning of FXR antagonist.
Fig. 6. Pincipal component analysis of gut microbiota of Indonesian containing T2D and obese subjects. T2D subjects with high FBG level (red circle) had high abundance of Bacteroides. Obese subjects localized in bottom part had high abundance of Romboutsia. (P. Therdtatha et al., Microorganisms. 2021. doi: 10.3390/microorganisms9050897)
Fig. 7. The level of Bacteroides fragilis and ursodeoxycholic acid (UDCA) and conjugated UDCAs in our Indonesian subjects ordered from left to right according to FBG level. This shows highly colonization of Bacteroides fragilis in high FBG subjects and depletion of UDCA and conjugated UDCA, except for subjects administered antidiabetic drug, metformin (red asterisk).(P. Therdtatha et al., Microorganisms. 2021. doi: 10.3390/microorganisms9050897)
