http://gastroenterology.medscape.com/reuters/prof/2001/02/02.02/20010201scie002.html

Reading the last paragraph regarding "the consequences of manipulating
the gut flora"
would indicate newborns must ingest colostrom and breastmilk
exclusively.
Judy Ritchie


Gut Microbes Modulate Intestinal Gene Expression


WESTPORT, CT (Reuters Health) Feb 01 - Colonization by gut microbes such
as
Bacteroides thetaiotaomicron modulates the expression of several genes
important in intestinal function, according to a report in the February
2nd issue of
Science.

In an effort to identify the potential impact of commensal organisms on
intestinal
function, Dr. Jeffrey I. Gordon, from Washington University School of
Medicine,
in St. Louis, Missouri, and colleagues colonized germ-free mice with
Bacteroides
thetaiotaomicron and used DNA microarrays to assess the host
transcriptional
response to colonization.

mRNA transcripts represented by 95 probe sets increased by at least
twofold with
colonization, the authors report, and mRNA transcripts represented by 23
probe
sets decreased.

Increases were especially evident in genes involved in host nutrient
absorption
and processing, the report indicates. Colonization increased the
expression of
sodium/glucose cotransporter, several components of lipid absorption,
and a
number of genes responsible for micronutrient absorption.

Colonization with B. thetaiotaomicron, which does not generate an
inflammatory
response, also enhanced expression of genes that should limit mucosal
damage
resulting from complement activation and prevent bacteria from breaching
the
epithelial barrier, the researchers note.

Bacterial colonization also reduced the expression of genes involved in
metabolism of xenobiotics and toxins and increased the expression of
genes
encoding proteins mediating enteric neurotransmission and motility, the
results
indicate.

Colonization with different microorganisms resulted in variations in
gene
expression, the investigators write, some of which suggest "that
variations in
xenobiotic metabolism between individuals may arise, in part, from
differences in
their resident gut flora."

"This commensal bacterium modulates expression of genes involved in
several
important intestinal functions, including nutrient absorption, mucosal
barrier
fortification, xenobiotic metabolism, angiogenesis, and postnatal
intestinal
maturation," the authors conclude. "The species selectivity of some of
the
colonization-associated changes in gene expression emphasizes how our
physiology can be affected by changes in the composition of our
indigenous
microflora."

"By identifying which of our genes are manipulated by microbes (and
how), we
may gain new appreciation of the functions of these genes, and identify
new
therapeutic strategies," Dr. Gordon told Reuters Health.

"The scope of functions legislated by microbes in the gut suggests that
we need to
carefully examine the consequences of manipulating this flora, both in
early
postnatal development and during adulthood. We also need to develop new
ways
of defining the composition of these indigenous microbial societies in
healthy
individuals, and groups of patients with a variety of illnesses," Dr.
Gordon
concluded.

Science 2001;291:881-884.

             ***********************************************
The LACTNET mailing list is powered by L-Soft's renowned
LISTSERV(R) list management software together with L-Soft's LSMTP(TM)
mailer for lightning fast mail delivery. For more information, go to:
http://www.lsoft.com/LISTSERV-powered.html