Role of Intestinal Microbiota in Ulcerative Colitis

Theoretical part
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4. Modulation of the gut microbiota
on colitis, since the non‐digestible carbohydrates should be able to reach the distal part of the
colon and stimulate the activity of the microbiota in this colon region. Production of non‐digestible
carbohydrates with high molecular weight may help increase the persistence of the compound
leading to slower fermentation, thus penetrating prebiotic effect all the way throughout the colon
and not only affecting the microbiota in the ascending region (Vernazza et al., 2006;Rastall, 2007).
Langlands et al. (2004) examined the prebiotic effect of a mixture of inulin (DP range 6‐60) and
FOS (DP range 2‐8). The study showed that the mixture could significantly increase the level of
bifidobacteria and lactobacilli in both the ascending and descending colon of healthy human
subjects. Approaches for slowly fermentation do not only include high chain length. Rose et al.
(2010) demonstrated that starch‐entrapped microspheres could be used to decrease the
fermentation rate.
The ability of non‐digestible carbohydrates to improve the colonic environment is not only
restricted to the properties through fermentation. Other studies have shown that the exogenous
structure of specific non‐digestible carbohydrates can affect the presence of pathogenic bacteria.
One of the features is the ability of some prebiotics (e.g. FOS and GOS) to act as a molecular
receptor decoy, which can competitively inhibit bacterial adhesion (Kunz et al., 2000;Shoaf et al.,
2006;Gibson et al., 2006). Another feature is the ability of prebiotic candidates (e.g. XOS and
cellobiose) to act as a repressor of virulence factors by repressing the gene expression in
enteropathogens such as Listeria monocytogenes (Gilbreth et al., 2004). In addition, a recent in
vitro study using Caco2 cells has shown that FOS could initiate an anti‐inflammatory response even
in the absence of intestinal bacteria by inducing the nuclear receptor PPAR gamma (Zenhom et al.,
2011). Table 3 summarizes the desirable attributes of prebiotics.
Table 3: Desirable attributes of prebiotics
Action Properties Reference
Colonic fermentation Selectively metabolized by bacteria with (Fooks and Gibson,
health promoting effects
2002;Rastall, 2007)
Persistence through the Reaching both the proximal and to some (Langlands et al., 2004)
colon
extent the distal colon.
Inhibition of adhesion Possessing receptor like sequences. (Kunz et al., 2000;Shoaf et al.,
by pathogens
2006;Gibson et al., 2006)
Repression of
pathogenic bacteria
Down‐regulating virulence factors. (Gilbreth et al., 2004)
Immune modulation Regulating anti‐inflammatory responses (Zenhom et al., 2011)