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Global Translational Medicine Gut microbiota in Onco-Hematology

Figure 1. An example illustrating the use of animal models in studies of cancer and gut microbiota.

−/−
of proliferation, which results in resistance to cell death facility provided a protective effect in Atm mice and the
[51]
(apoptosis) . Using animal cancer models, such as p53- conventional microbiota presented with a more pathogenic
deficient mice, enables researchers to circumvent some effect. The microbe that was found to be highly enriched
steps necessary for overt cancer, saving time and animal in the restricted microbiota was Lactobacillus johnsonii
numbers. Apc Min/+ mice (commonly develop intestinal An inoculation with L. johnsonii in Atm −/− mice decreased
polyps spontaneously) have been used to demonstrate that inflammation, DNA damage, and oxidative stress . Such
[58]
the infection of Citrobacter species (Citrobacter rodentium) results indicated that gut microbiota could have an impact
or enterotoxin produced by Bacteroides fragilis can trigger on the growth and development of lymphoma (lymphoma-
−/−
colon cancer [52,53] . Helicobacter hepaticus infection is also genesis) in Atm mice. It may be reiterated that other
associated with the promotion of liver tumorigenesis based types of lymphoma or cancer models may also contribute
on a chemically induced model of liver cancer . to the growing evidence which links the microbiota to
[54]
Yamamoto et al. demonstrated that mice deficient carcinogenesis.
[55]
in the ataxia-telangiectasia mutated gene (Atm −/− mice), 3.3. Novelty concerning gut microbiota in
which exhibit genetic instability and development of an immunotherapy
impetuously high incidence of thymic lymphoma [55-57] , as a
consequence of the sensitivity to changes in the microbial It may be mentioned that therapy immunotherapies and
content . It was discovered that when Atm mice were other improvements associated with other forms of therapy
[58]
−/−
placed in more sterile conditions, they lived longer with seem to have discounted gut microbiota as a part of cancer
a decreased lymphoma penetrance [58,59] . On the contrary, therapy until recent times. Anticancer immunotherapy,
when mice were placed under standard specific pathogen- in the context of immune checkpoint inhibitory (ICI)
free (SPF) conditions, their lymphoma latency and lifespan antibodies administration, prevents tumor growth by
decreased. Further testing was performed to investigate the inhibiting immunosuppression or immunosuppressive
effects of the gut microbiota using a more direct approach: pathways. A beneficial or favorable gut microbiota
[60]
mice were placed in a restricted microbiota facility . The possesses an ability to increase or augment the efficacy of
mice were “conventionalized,” where they were inoculated immune checkpoints and also moderate immune-related
[61]
with fecal samples from conventional SPF mice. In a similar adverse reactions (Figure 2) .
fashion, the “conventionalized” mice had shorter lifespans Since gut microbiota has been discovered to play an
when compared to mice with a restricted flora . Therefore, important role in modifying responses toward cancer
[58]
the results showed that microbes in the restricted, sterile immunotherapy Vetizou et al. and Sivan et al. ,
[63]
[62]
Volume 2 Issue 2 (2023) 5 https://doi.org/10.36922/gtm.0389