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Gut Microbes 2:4, 256-261; July/August 2011; © 2011 Landes Bioscience
ARTICLE ADDENDUM
256 Gut Microbes Volume 2 Issue 4
Key words: probiotics, depression,
anxiety, stress, side effects, human
subjects
Submitted: 04/20/11
Revised: 07/07/11
Acce pted: 07/21/11
ht tp : //d x .do i.org/10.4161/gmic .2.4 .16108
*Correspondence to: Michaël Messaoudi;
Email: mmessaoudi@etap-lab.com
In a recent clinical study, we dem-
onstrated in the general population
that Lactobacillus helveticus R0052
and Bifidobacterium longum R0175
(PF) taken in combination for 30 days
decreased the global scores of hospital
anxiety and depression scale (HADs),
and the global severity index of the
Hopkins symptoms checklist (HSCL-
90), due to the decrease of the sub-scores
of somatization, depression and anger-
hostility spheres. Therefore, oral intake
of PF showed beneficial effects on anxi-
ety and depression related behaviors in
human volunteers. From there, it is inter-
esting to focus on the role of this probi-
otic formulation in the subjects with
the lowest urinary free cortisol levels at
baseline.
This addendum presents a secondary
analysis of the effects of PF in a sub-
population of 25 subjects with urinary
free cortisol (UFC) levels less than
50 ng/ml at baseline, on psychologi-
cal distress based on the percentage
of change of the perceived stress scale
(PSs), the HADs and the HSCL-90
scores between baseline and follow-up.
The data show that PF improves the
same scores as in the general popula-
tion (the HADs global score, the global
severity index of the HSCL-90 and three
of its sub-scores, i.e., somatization,
depression and anger-hostility), as well
as the PSs score and three other sub-
scores of the HSCL-90, i.e., “obsessive
compulsive,” “anxiety” and “paranoid-
ideation.” Moreover, in the HSCL-90,
Beneficial psychological effects of a probiotic formulation
(Lactobacillus helveticus R0052 and Bifidobacterium longum R0175)
in healthy human volunteers
Michaël Messaoudi,1,* Nicolas Violle,1 Jean-François Bisson,1 Didier Desor,2 Hervé Javelot3 and Catherine Rougeot4
1ETAP-Ethologie Appliquée; 2Equipe de Neurosciences Comportementales ; UR AFPA; INR A UC340 ; INPL -UHP;
3Unité INSER M U954-Nutrition-Génétique et exposition aux risques environnementaux; Faculté de Médecine de Nancy; Université Henri Poincaré;
Vandoeuvre-lès-Nancy, France; 4Institut Pasteur; Unité de Biochimie Structurale et Cellulaire/UR A2185 CNRS ; Paris, France
the score of the Factor 1, related to
anxiety and depression, is significantly
improved over time in PF-treated sub-
jects compared with controls.
Additional preclinical data showed
that PF formulation does not induce side
effects such as addiction or learning and
memory impairments, and therefore dis-
plays a good safety profile.
Complementary hypothetical mecha-
nisms of action are proposed to explain
the functioning of the brain-gut axis,
particularly the relationship between
probiotics and stress-related psychopa-
thologies, such as anxiety and depression.
Introduction
Animal studies have shown that experi-
mental manipulations of the enteric
microbiome can modify host’s neural
function, potentially leading to altered
emotional and cognitive functions dur-
ing adulthood. The first evidence came
from studies comparing germ-free and
gnotobiotic animals.1,2 Despite the intrin-
sic artificial nature of the experimental
situation, it clearly demonstrated that gut
microbiota alterations in pups can disturb
the development of stress-related HPA-
axis function.1 In that study, germ-free
mice presented an increased HPA-axis
responsiveness to a psychological stress
during adulthood compared to specific
pathogen free mice and gnotobiotic mice
associated with a single bacterium at the
neonate stage. Germ-free adult mice also
presented a decreased sensitivity to the
Addendum to: Messaoudi M, Lalonde R, Violle
N, Javelot H, Desor D, Nejdi A, et al. Assessment
of psychotropic-like properties of a probiotic
formulation (Lactobacillus helveticus R0052
and Bidobacterium longum R0175) in rats and
human subjects. Br J Nutr. 2011 Mar;105(5):755-64;
PMID: 20974015; DOI: 10.1017/S0007114510004319
www.landesbioscience.com Gut Microbes 257
ARTICLE ADDENDUM
ARTICLE ADDENDUM
notable are stress-induced reductions in
lactobacillus and bifidobacteria species.
Thus, gut bacteria and the brain seem to
interact in a close relationship using vari-
ous positive and negative feedbacks. The
value of probiotics as preventive and/or
adjuvant therapeutics in stress-related dis-
eases seems sound.
Psychotropic-Like Effects
of Lactobacillus helveticus R0052
and Bidobacterium longum
R0175 Formulation
in the General Population
and in a Sub-Population
with Low Urinary Free
Cortisol Levels
In our recent study performed in the
general population,24 Lactobacillus helve-
ticus R0052 and Bifidobacterium longum
R0175 (PF) (Institut Rosell-Lallemand,
Blagnac, France), taken daily in combi-
nation for 30 days, decreased over time
the global score of the hospital anxi-
ety and depression scale (HADs) and
the global severity index (GSI) of the
Hopkins symptoms checklist-90 (HSCL-
90), due to the decrease of the sub-scores
of the “somatization”, “depression” and
“anger-hostility” spheres. The results
suggest that in the general population,
PF formulation is beneficial in reducing
anxiety and stress response, as well as
improving mood in moderately stressed
human subjects.
In the light of the results of a clini-
cal trial involving the administration of
Lactobacillus casei strain Shirota to healthy
adults showing that subjects with the low-
est score in the depressed/elated dimension
at baseline had significant improvement in
mood scores after taking the probiotic,25
we wondered what could be the effects of
PF in subjects who have the lowest uri-
nary free cortisol (UFC) levels at baseline?
Since our goal was to focus on less stressed
subjects, we determined the median of the
UFC in the studied population (50 ng/
ml) and chose to include in the explor-
atory secondary analysis only subjects
with UFC levels lower than that median
value at baseline. Thus, this analysis of the
data was conducted in a sub-population of
25 subjects, 10 PF and 15 placebo, with
UFC levels between 10 and 50 ng/ml at
pro-inflammatory cytokines was detected
at this time, suggesting a role for the vagus
nerve in the modulation of behavior. The
authors then reproduced a similar anxio-
genic-like effect in mice in several stud-
ies, investigating the neuronal pathways
implicated in the processing of the viscero-
sensory information ultimately leading to
behavioral response.12-14 They also showed
that such an anxiogenic effect occurred at
the early stages of the infection, 7–8 hours
post-colonization.14, 15 The overall results
clearly demonstrate that this bottom-up
gut-brain axis can produce, in a few hours,
anxiety-related behaviors supposed to be
appropriate for coping with threats associ-
ated with future sickness.16
Along with these results which indi-
cate that the gut microbiota status can
negatively affect the mental well-being of
the host, appears the possibility of novel
prophylactic or therapeutic approaches to
stress-related disorders such as depression
and anxiety. One of these approaches may
consist in oral administrations of selected
commensal bacteria, usually referred to as
probiotics, in order to restore or improve
the gut microbiome. Recently, such a
strategy has been successfully applied and
evidence from various preclinical studies
suggests that probiotics or microbes could
be used to reduce stress, and therefore
some of its related pathologies. A prepa-
ration containing Lactobacillus rhamnosus
and Lactobacillus helveticus has been dem-
onstrated to improve colonic function and
colonization, and to normalize corticoste-
rone levels in rat pups submitted to mater-
nal separation stress.17 In the same way,
it was reported that oral treatment with
Bifidobacterium infantis reduced depres-
sive-like behavior of rats in the forced
swimming test18 and that Bifidobacterium
longum prevented anxiogenic-like effects
of a chronic infection with the gut parasite
Trichuris muris in mice.19 In a recent arti-
cle, it was reported unpublished data indi-
cating that mice treated with Lactobacillus
reuteri exhibited reduced plasmatic corti-
costerone levels after stress exposure and
a decreased anxiety-like behavior in the
elevated plus-maze.20
Preclinical and clinical trials have
shown that a variety of psychological and
physiological stressors can impair normal
intestinal microbiota in turn,21-23 and most
negative feedback exerted by glucocor-
ticoids on the HPA-axis.2 The reversal
of the HPA-axis alteration was possible
only if bacterial colonization occurred
before the mice reached six weeks of age,
suggesting a role for enteric bacteria in
the brain development with possible long-
lasting effects. Moreover, in recent studies
in germ free mice, it was suggested that the
gut microbial colonization process induces
neurochemical changes in the brain and
initiates signaling mechanisms that affect
neuronal pathways implicated in motor
control and anxiety-like behaviour.3,4
These changes were associated to
significantly lower concentrations of
brain-derived neurotrophic factor, nor-
epinephrine and serotonin in the cortex
and the hippocampus of these mice. The
authors also reported a downregulation
of the N-methyl-D-aspartate (NMDA)
receptors, i.e., NR1 and NR 2 subunits, in
the cortex and the hippocampus.1,2 Since
NMDA receptors in the hippocampus are
implicated in long-term memory consoli-
dation,5 these results are in good accor-
dance with those of a study which recently
demonstrated memory impairments in
such germ-free mice.6 Interestingly, simi-
lar brain modifications have also been
described in animals following stress
exposure, along with depressive-like
behavior and reduced memory abilities.7-9
Taken together, these results suggest that
an impaired gut colonization during the
early stages of life may dramatically con-
tribute to an exaggerated stress response
during adulthood, potentially facilitating
the appearance of related pathologies such
as anxiety and mood disorders. Regarding
this hypothesis, it seems critical to better
determine the extent to which gut micro-
biota composition in early life influences
mental well-being during adulthood in
animal models more connected to the
human situation.
Besides the possible long-lasting
delayed influence of microbiota on the
brain, animal studies demonstrated that
gut bacteria can affect mood and behav-
ior in an acute way. It was demonstrated
that mice orally treated with an enteric
pathogen were more anxious than control
mice.10, 11 Indeed, infected mice presented
no evidence that bacteria reached blood
circulation and no elevation of circulating
258 Gut Microbes Volume 2 Issue 4
or via cytokine transporters at the blood-
brain barrier where pro-inflammatory
cytokines could gain access to the brain
through these saturable transport sys-
tems.33 Another pathway may consist in
the activation of interleukin-1 receptors,
located on perivascular macrophages
and endothelial cells of brain venules, by
circulating cytokines inducing local
production of prostaglandin E2.34 ,35
Interestingly, several studies demonstrated
that inflammatory responses in rodents
are attenuated by lactobacilli and bifido-
bacterium strains,30,36,37 while antidepres-
sant-like properties of oral administration
of infantis in stressed animals were asso-
ciated with anti-inflammatory effects.18
Very recently, we have shown that a
formulation containing Lactobacillus
helveticus R0052 and Bifidobacterium
longum R0175 in combination with
Lactobacillus rhamnosus R0011, reduced
the serum levels of pro-inflammatory
cytokines interleukin-1α, interleukin-6,
interferon-γ and tumor necrosis factor-α
following an Escherichia coli infection in
rats.38 In addition, probiotic-treated rats
showed a significant increase of serum
levels of anti-inflammatory cytokines
interleukin-4 and interleukin-10 in com-
parison with controls. Thus, the benefi-
cial psychological effects of a chronic oral
treatment with Lactobacillus helveticus
R0052 and Bifidobacterium longum R0175
If the probiotics reduce stress and its
related disorders through gut-brain sig-
naling, will they interact with antide-
pressant and anxiolytic agents, inhibiting
their effects or enhancing their effects and
lowering the drug concentrations needed?
Further studies are needed to evaluate the
effects of coadministration of probiot-
ics with psychotropic drugs in terms of
interaction.
Possible Underlying Mechanisms
In addition to the assumptions made in
our recent article in reference 24, other
hypothetical mechanisms are proposed to
explain the beneficial effects of probiotics
in psychopathological disorders such as
anxiety and depression.
Pro-inflammatory cytokines could act
as mediators in case of gut infection to
induce anxious behavior in mice,19 and
the involvement of inflammation in the
depressive syndrome is well-known.30
Various cytokine receptors have been
found on peripheral nerves including
the vagus nerve and spinal nerves that
may signal inflammation to the brain,
potentially evoking anxiety and depres-
sion.31 However, even if vagotomy does
not always prevent the anxiogenic and
depressant effects of inflammation, cyto-
kines could enter the brain via circum-
ventricular organs by volume diffusion32
baseline, on psychological distress based
on the percentage of change of the per-
ceived stress scale (PSs), the HADs and
the HSCL-90 scores between baseline and
follow-up. It was shown that PF improved
the same scores as in the general popula-
tion (see above), as well as the PSs score
(Fig. 1), and three other sub-scores of the
HSCL-90, i.e., “obsessive compulsive”,
“anxiety” and “paranoid-ideation” (Fig.
2). Moreover, in the HSCL-90, the score
of the Factor 1, related to anxiety and
depression,26 was significantly improved
over time in PF-treated subjects compared
with controls (Fig. 3).
Exposure to chronic stress could dis-
rupt the balance of intestinal microbiota
and induce various diseases. Therefore,
whatever the stress level, daily intake of
probiotics could prevent such an imbal-
ance, and the improvement in symptoms
among subjects with low to mild stress
levels suggests the value of prophylactic
intake of probiotics in terms of digestive
comfort and general well-being.
The risks of addiction and memory
impairment are common expected side-
effects encountered with psychoactive
drugs. For this reason, these risks should
be assessed as part of the safety evaluation
of all new nutritional or pharmacological
neuroactive agents. For this purpose, to
assess the safety profile of PF in relation
with addiction and learning and memory
disorders, the conditioned place prefer-
ence paradigm (CPP),27 and the passive
avoidance test (PAT),28 were performed
respectively in rats using methods derived
from those described by Messaoudi et al.29
The results demonstrated that PF did not
have rewarding properties in the CPP, sug-
gesting no abuse potential compared with
morphine (Fig. 4), and does not induce
learning and memorization deficit in the
PAT as is the case with diazepam (Fig. 5).
Therefore, these results reinforce the idea
that consumption of selected probiotics
may represent a safe and natural prophy-
lactic approach against some stress-related
psychological disorders.
Despite the fast growing interest in the
impact of probiotics on stress, anxiety and
depression, the underlying physiological
mechanisms by which probiotics might
influence mental health remain largely
unknown and hypothetic.
Figure 1. Eects of PF (dashed box plot) (n = 10) and placebo (white box plot) (n = 15) on the
percentage of improvement of the perceived stress scale (PSs) and the hospital anxiety and de-
pression scale (HADs) scores between baseline and follow-up in subjects with low urinar y cortisol
levels at baseline. Mann-Whitney U-test: *p < 0.05 (PF vs. placebo). Data are the 10th, 25th, 50th
(median), 75th and 90th percentiles.
www.landesbioscience.com Gut Microbes 259
been demonstrated yet. One hypothesis
to consider is that probiotics could pro-
duce neurotransmitters to act directly or
indirectly on specific targets in the central
nervous system, since it was demonstrated
that some bacteria are able to produce
acetylcholine or gamma-aminobutyric
acid.40, 41
Another mechanism whereby probi-
otic bacteria might have an influence on
mood is via regulation of glycemic con-
trol. Indeed, emerging research shows
that the intestinal microbiota contributes
to the glucose tolerance42 and that epide-
miological studies have made associations
between glucose intolerance and risk of
depression.43,44
Otherwise, probiotic strains might be
able to act on the reduction of substance P
in the gut,45 since it was shown that altera-
tions to the normal gut microbiota can
increase substance P release in the nervous
system and promote behaviors reflective of
anxiety, depression and aggression.46,47
Conclusion
In our recent study, preliminary results
indicate that oral administration of
selected bacteria may have some beneficial
properties in the treatment of gastrointes-
tinal and psychological stress-related dis-
orders. Nevertheless, further studies are
periaqueductal gray, via the vagus nerve
independently of inflammation.16 In the
same way, probiotics can reduce the acti-
vation/sensitization of neuronal circuits
involved in stress-induced visceral hyper-
algesia both at the spinal and supraspinal
levels in the spinal cord, the paraventricu-
lar nucleus and the medial nucleus of the
amygdala.39 However, such a mediator
between bacteria and neurons has not
in humans may be explained, at least in
part, by the anti-inflammatory properties
of these bacteria.
Probiotics could also exert their effects
by modulating the activity of brain
structures involved in the processing of
emotions related to anxiety, mood and
aggression, including the septum, the
central nucleus of the amygdala, the bed
nucleus of the stria terminalis and the
Figure 2. Eects of PF (dashed box plot) (n = 10) and placebo (white box plot) (n = 15) on the percentage of improvement of HSCL-90 global severity
index (GSI) and some sub-scores bet ween baseline and follow-up in subjects with low urinary cor tisol levels at baseline. Mann-Whiney U-test: #p < 0.10;
*p < 0.05, **p < 0.01 (PF vs. placebo). Data are the 10th, 25th, 50th (median), 75th and 90th percentiles.
Figure 3. Eects of PF (dashed box plot) (n=10) and placebo (white box plot) (n=15) on the
percentage of improvement of HSCL-90 sub-scores of Factor 1 (Anxiety-Depression), Factor 2
(Paranoid-Psychotic) and Factor 3 (Panic-Phobia) between baseline and follow-up in subjects with
low urinary cortisol levels at baseline. Mann-Whitney U-test: **P<0.01 (PF vs. placebo). Data are
the 10th, 25th, 50th (median), 75th and 90th percentiles.
260 Gut Microbes Volume 2 Issue 4
13. Goehler LE , Gayka ma RPA, Opitz N, Reddaway
R, Badr N, Lyte M. Activation i n vaga l afferents
and central autonomic pathway s: early responses to
intestinal in fection with Campylobacter jejuni. Brain
Behav Im mun 2005 ; 19:334 -44.
14. Goehler LE, Park SM, Opitz N, Lyte M, Gaykam a
RPA . Campylobacter jejuni infection increases anx-
iety-li ke behav ior in the holeboard: possible ana-
tomica l substr ates for vi scerosensory modulation
of exploratory behavior. Brain Beh Immun 2008 ;
22:354-66.
15. Lyte M, Li W, Opitz N, Gaykema RP, Goehler LE.
Induction of anxiety-like behavior in mice during the
initia l stages of infection wit h the agent of murine
colonic hyperplasia Citrobacter rodentium. Physiol
Behav 20 06; 89:350-7.
16. Goehler LE , Lyte M, Gaykema R PA. Infec tion-
induced v iscerosensory signals from gut enhance
anxiety: implic ation for psychoneuroimmunology.
Brain B ehav Immu n 2007; 21:721-6.
8. McEwen BS. Central effects of stress hormones in
health and dise ase: underst andin g the protective and
dama ging ef fects of stress a nd stres s mediators. Eur J
Phar ma co l 200 8; 583 :174- 85.
9. Sapolsk y RM. Stress and plasticity in the limbic
system. Neurochem Res 2003; 28:1735-42.
10. Lyte M, Varcoe J J, Baile y MT. Anxiogenic effect of
subcli nical bacterial infection in mice in the absence
of overt im mune activation. Physiol Behav 1998 ;
65: 63 -8.
11. Lacost a S, Meral i Z, Anisman H. Behavior al and
neurochemical consequences of lipopolysaccharide
in mice : anx iogenic-like ef fects. Brain Re s 1999;
818: 291-3 03.
12. Gaykema RPA, Goehler LE , Lyte M. Br ain response
to ceca l infec tion with Campylobacter jejuni : analy-
sis with Fo s immunoh istochemistr y. Brain Beh av
Immun 20 04; 18 :238- 45.
needed to confirm the potential therapeu-
tic effects of probiotics in different sub-
sets of subjects, and to better understand
their underlying mechanisms of action.
Then it would be of particular interest
to determine in patients prone to anxiety
and depression, if a probiotic preparation
could potentiate chemotherapeutic agents
and could therefore be used as an adjuvant
therapy, or could replace them in part.
On the basis of the secondary analysis
of our data, results suggest that the effi-
ciency of PF may differ depending on the
stress state of individuals. Thus, a chronic
use of Lactobacillus helveticus R0052 and
Bifidobacterium longum R0175 for mula-
tion could also contribute to mental well-
being of subjects with low levels of stress,
and could represent a prophylactic strat-
egy against stress-related diseases in the
population subject to the constraints of
daily life.
Disclosure of Potential Conflict of Interest
This clinical trial was funded by Rosell-
Lallemand SAS, France. None of the
authors has any financial relationship with
the funding sponsor and no interest in
sales of this product.
Acknowledgments
The authors thank the Rosell-Lallemand
Group for supplying PF samples
(Probio’Stick®). The authors are also
grateful to Miss Amanda King for her
English revision.
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