Science 28Feb2020

microbial community in infants ( 19 )andthus
potentially influences the development of the
host metabolic system. However, 16Sribosomal
DNA (rDNA) amplicon sequencing showed
that the relative abundance of bacterial families
constituting the gut microbiota was similar in
offspring from SPF and GF ICR mothers during
adulthood, although GF offspring in infancy
showed significant decreases in Streptococcaceae
and Enterococcaceae compared with SPF off-
spring (fig. S3A). Principal coordinate analysis
based on weighted UniFrac distances con-
firmed that there were no differences between
the two groups during adulthood, but not during
infancy(fig.S3B).Toexcludethepossiblein-

fluence of the vaginal microbiota, newborns

from SPF and GF mothers were also delivered

by caesarean section. Consistent with vaginally

delivered offspring, caesarean GF offspring ex-

hibited severe obesity upon HFD feeding during

growth (fig. S4A). WAT and liver weight, plasma

metabolic parameters,and insulin levels were

also significantly higher in the caesarean GF

offspring at 16 weeks than in the caesarean SPF

offspring (fig. S4, B to D). Furthermore, the

former showed reduced energy expenditure

(fig. S4E). Additionally, compositions of the

gut microbiota were similar between caesarean-

delivered offspring from the SPF and GF mothers

during adulthood, whereas infant microbiota

may be affected slightly by the delivery modes

(fig. S5, A and B), consistent with the findings

of a recent study ( 19 ). Collectively, these data

show that the gut microbiota in adulthood is

not a primary factor in the obesity-prone phe-

notype of the GF offspring.

Interaction between the gut microbiota and

host genetics modulates the predisposition

to obesity, whereas environment factors such

as diet are indispensable for the regulation of

host-microbe interaction ( 20 – 22 ). Although gut

microbial compositions tended to be different

between offspring from ICR and C57BL/6J

mothers (fig. S6, A and B), they showed a sim-

ilar obesity phenotype (Fig. 1, A to F and figs.

Kimuraet al.,Science 367 , eaaw8429 (2020) 28 February 2020 2of12

Fig. 1. Offspring from GF mothers

exhibit severe obese phenotype when

fed a HFD.(A) Experimental scheme

(left). Body weight changes during the

HFD trial (middle) (n= 14 animals per

group) and tissue weights (right) (n=7to

9 tissues per group). epi, epididymal; peri,

perirenal; sub, subcutaneous. (B) Plasma

glucose, TGs, NEFAs, and total cholesterol

levels (n= 6 to 11 plasma samples per

group). mEq, milliequivalents. (C) Body

temperature (left) (n= 7 or 8 animals per

group) and heart rate (right) (n=7

animals per group). (D) Gut hormone PYY

(left) (n= 6 or 8 plasma samples per

group) and GLP-1 (right) (n= 6 plasma

samples per group) levels. (E) Energy

expenditure (n= 7 or 8 animals per

group). (F) Glucose tolerance test (left)

and insulin tolerance test (right) (n=8

animals per group). Male mice were

analyzed at 16 weeks of age. Student’s

ttest; **P< 0.01 and *P< 0.05. Data are

presented as means ± SEM. Offspring

from three or four litters per group were

used. SPF, conventional offspring derived

from ICR SPF mothers; GF, conventional

offspring derived from ICR GF mothers.

4 8 12 16

0

20

40

60

80

Body weight (g)

Weeks of age

SPF

GF

SPF GF

*

**

**

**

**

**

**

****

**

******

1cm

14

12

10

8

0

Energy expenditure

(kcal/kg/hr)

Time

*

Light Dark

**

**

SPF

GF

****

**

*

****

****

E

SPF

PYY (ng/mL)

2.5 *

1

0.5

0

1.5

2

GF SPF

GLP-1 (pg/mL)

18 *

6

0

12

GF

D

B

F

C

0

SPF

550

650

750

Heart rate (beats/min)

*

GF

0

SPF

37.5

38.5

39.5

Body temperature (

) *

GF

Plasma glucose (mg/dL )SPF GF

500 **

200

100

0

300

400

SPF GF

NEFAs (mEq /L)

0.8 **

0.2

0

0.4

0.6

Total cholesterol (mg/ dL )SPF GF

160 **

40

0

80

120

SPFGF

TGs (mg/dL)

80 **

20

0

40

60

0

Time (min) after glucose i.p.

0

200

400

500

Plasma glucose (%)

100

300

30 60 90 120 90

*

*

*

*

0

Time (min) after insulin i.p.

0

120

30 60 120

40

(^80) *

• 
  
  
  
  • SPF
    GF
    A
    **
    0
    epi peri sub liver
    1
    2
    3
    4
    5
    Tissue weight (g)
    WAT

    ---

    
    

    SPF
    GF
    SPF GF
    WAT (peri)
    1cm
    Pregnancy day 18.5
    SPF Mother Germ-FreeMother
    Conventional Foster MotherConventional Foster Mother
    After weaning,
    High-fat diet feeding
    After weaning,
    High-fat diet feeding
    ConventionalFosterMotherConventionalFosterMo
    RESEARCH | RESEARCH ARTICLE