Scientific Session of Microbiology Research Center (MRC) & Innovation Center of Pasteur Institute of Iran

1. 1
Microbiota in Health &
Diseases
Welcome to your
microbial life!
Seyed Davar Siadat (Prof. of Medical Microbiology)
Head of Microbiology Research Center (MRC) & Innovation Center
Pasteur Institute of Iran

3. Each of us consists of about 40 trillion human cells and about 22,000 human genes
, but as many as 100 trillion microbial cells (the microbiota) and 10 million
microbial genes (the metagenome). The term ‘‘supraorganism’’ has been coined
to describe the fact that we are ‘‘running fermenters,’’ carrying numerically more
bacteria than we have cells in our body.
However, we are only beginning to understand the impact of the microbiota on
health.

6. GUT MICROFLORA
Age
Diet composition
LCPUFA, Protein,
Nucleotide, Lactose, FIF
Gene receptor?
Mode of birth
Maternal flora
Infant
environment
Antibiotics,
drugs Probiotics
Non –digestible
carbohydrate,
Prebiotics
Factors influencing colonisation

7. • Question: Can non-caloric artificial
sweeteners modulate the composition
and/or function of the gut microbiota
and thus affect host glucose
metabolism?
Credit: Weizmann Institute of Science
Saccharin
Sucralose
Aspartame
Nature. 2014 Oct 9;514(7521):181-6.

8. Development of the Gut Microbiota
birth 4 days 4-6 months20 days
dietary influence
prepartal
aseptic diverse microbiota
oral inoculation
with maternal
intestinal/vaginal
microbiota

9. Difference in gut microbiota in Breast- and
Formula-fed Infants
Breast-fed infant
0 5 10 15 20 25
Days
%oftotalfaecalmicro-organisms
Formula-fed infant
Days
0
10
20
30
40
50
60
70
80
90
100
%oftotalfaecalmicro-organisms
Bifidobacteria
E. coli
Bacteroides
According to Harmsen et al.,
0 5 10 15 20 25
0
10
20
30
40
50
60
70
80
90
100

10. Functions of Normal Flora
• Digestion &Production of vitamins
• Mucosal maturation
• Maturation & development of Immune System
• Metabolism & Cell signaling
• The Gut- Brain , Gut – Lung , Gut – Kidney, Gut
Liver Axis
• Colonization resistance

11. Association of Microbiota in:
Physiology & Diseases
• Diabetes
• Rheumatoid
Arthritis
• MD
• MS
• Atherosclerosis
.
• Fibromyalgia
• some cancers
• IBS and IBD
• common obesity
• Anxiety,
Depression, Mood
&…….

15. Components of the intestinal barrier
NATURE REVIEWS | MICROBIOLOGY VOLUME 14 | JANUARY 2016 | 21
Physical barrier
(the epithelium)
Chemical barrier
(mucus layer)
Immunological
barrier
(immune cells of the lamina
propria)
Microbial barrier
(commensal bacteria)
Muscle layers
(smooth muscle intestinal
wall)

16. Human health and disease condition are controlled
by:
neural , endocrine, metabolic and immunological
pathways.

17.  Pattern Recognition Receptors (PRRs)
 (MAMPs) = Microbe-Associated Molecular Patterns
 (DAMPs) = Damage Associated Molecular Patterns
like : HMGB1, DNA,RNA
Microbe products
recognized by TLRs

18. Ligand specificities of mammalian TLRs
NATURE REVIEWS | MICROBIOLOGY VOLUME 14 | JANUARY 2016 | 21

19. Tight junctions maintain barrier between epithelial
cells

21. Example 1: Stress , depression,,,,,,&
leaky hypothesis

22. Example 2: Life style, Nutrition,,,,
leaky hypothesis

24. GI and LIVER diseases associated
to LEAKY GUT/DYSBIOSIS
1. Gastrointestinal infections
2. Irritable Bowel Syndrome
3. Intestinal Bacterial Overgrowth
4. Food Intolerance/Allergy
5. Inflammatory Bowel Diseases
6. GI Cancer
7. Obesity and Metabolic Syndrome
8. Liver diseases
9. …

27. Diet-induced metabolic endotoxemia.
Alcock J and Lin HC 2015 [version 1; referees: 2 approved] F1000Research 2015, 4:738 (doi:
10.12688/f1000research.6078.1)

28. Figure 2. How insulin resistance is regulated by nutrients and microbiota.
Alcock J and Lin HC 2015 [version 1; referees: 2 approved] F1000Research 2015, 4:738 (doi:
10.12688/f1000research.6078.1)

30. Gut microbiota, enteroendocrine functions and metabolism

31. Schematic overview of the interactions between the gut microbiota, specific metabolites,
enteroendocrine L cell functions and targeted organs. Enteroendocrine L cells express several
G protein coupled receptors (GPCRs) (e.g. GPR43, GPR41, GPR119 and ...
Will be continued by Dr. Ejtahed& Ahmadi
…….

35. HDL: PAROXONASE , PAF_AH
Paraoxonase 1 (PON1) is located on HDL. Meta-analysis of clinical epidemiological
investigations reveals a substantial association of low serum PON1 activity with
coronary heart disease incidence independent of other risk factors including HDL
cholesterol and apolipoprotein AI (apoAI).
LDL: PAF_AH
Infection: CRP & SAA
How HDL protects LDL against atherogenic modification: paraoxonase 1 and other
dramatis personae. Current Opinion in Lipidology:
August 2015 - Volume 26 - Issue 4 - p 247–256

36. Paradox
new study describe higher concentrations of Lactobacillus spp.i n the obese gut
microbiota.
Researchers demonstrated that Lactobacillus reuteri was associated with obesity
in adults.
Additionally, Bervoets et al showed that the concentration of Lactobacillus spp.
is positively correlated to plasma hs-CRP levels in obese children and
adolescents.
An increased prevalence of positive Firmicutes to higher levels of plasma hs-CRP
These results seems therefore to suggest a possible role for Lactobacillus spp. in
“lowgrade” inflammation, a major pathophysiological process of obesity.
Interestingly, researchers detected an elevated Firmicutes-to -Bacteroidetes
ratio in the gut microbiota of obese children and adolescents. Previous
investigators also showed significant associations between this ratio and obesity
in mice and humans . Contrary to these findings, other studies described no or
even opposite differences in the Firmicutes-to-Bacteroidetes ratio between
obese and lean subjects . Possibly, these variations in study outcome are related
to the fact that different methodologies were applied in new studies.

37. In this study, important compositional differences in the faecal gut microbiota of obese and lean children were
revealed. This was generally reflected by an elevated Firmicutes-to-Bacteroidetes ratio in the obese study
population. At the species level, low proportions of B. vulgatus and high concentrations of Lactobacillus spp. were
found in faeces of obese children and adolescents.
Furthermore, the presence of Lactobacillus spp. in the obese gut microbiota was positively associated with plasma
hs-CRP levels. We also found a positive association between energy intake and the presence of Staphylococcus spp.
in faeces of children, independent of their BMI status. The aforementioned bacterial genera and species may thus
be more efficient at extracting energy from a given diet in obese children and adolescents compared with gut
microbiota of lean children. Hence, B. fragilis group, Lactobacillus spp. and Staphylococcus spp. play an important
role in the pathophysiology of childhood obesity. We hypothesize that an aberrant gut microbiota composition in
combination with influences of lifestyle factors might contribute to the development of childhood obesity.

38. Chlamydial lipopolysaccharide (LPS) has also been shown to enhance low-density
lipoprotein (LDL) uptake and to down-regulate cholesterol efflux in monocytes or
macrophages. It was also found that chlamydial heat-shock protein 60 (hsp 60), a highly
conserved stress protein with wide cross-reactivity, could also induce cellular oxidation
of LDL cholesterol .

39. Liver X receptors (LXRs):
nuclear receptors
• The systemic cholesterol balance and metabolism are
regulated by liver X receptors (LXRs) .
• LXR is critical for cholesterol homeostasis controlling
cholesterol levels by inducing RCT and promoting
degradation of lipid metabolism-related receptors
such as low density lipoprotein (LDL) receptor, very low
density lipoprotein (VLDL) receptor, and adiponectin
receptor 2 (AdipoR2).
Of interest, TLR4 inhibits activation of LXRs, presumably
through an MyD88-independent pathway.
recently demonstrated that TLR2 and TLR4 are essential
for RCT as apolipoprotein A-I,

40. Key components of reverse cholesterol transport.
Key components of reverse cholesterol transport. Cholesterol taken up by tissue macrophages is
transferred to HDL through membrane transporters like ABCA1 and ABCG1. HDL can then return to the liver
where its cholesterol can be converted to bile acids (BA) through a process mediated in large part by
Cyp7a. Finally, bile acids and cholesterol are delivered to intestine where they can be excreted in feces.
ABCG5 and ABCG8 appear important to cholesterol absorption/excretion. This simplified schema supports
reverse cholesterol transport as a potential target for limiting atherosclerosis by promoting cholesterol
removal from macrophages and foam cells at the arterial wall. CE indicates cholesteryl ester; FC, free
cholesterol.
Copyright © American Heart Association, Inc. All rights reserved.

41. Liver X receptors agonists regulate RCT in
macrophages, liver, and small intestine
• In macrophages, LXR stimulates expression of sterol
transporters ABCA1 and ABCG1 responsible for
cholesterol efflux
• In the liver, LXR up-regulates expression of
cholesterol-7-α-hydroxylase (CYP7A1) that is involved
in cholesterol catabolism to bile acids
• In macrophages, TLR2 and TLR4 suppress stimulation
of LXRs ,utilizes MyD88-dependent mechanism to
induce RCT.
• In summary, LXRs play a remarkable role
on crossroads of metabolic, cell cycle, and
immune signaling.
Will be continued by khodam…….(means me)

45. TMAO:
inhibits RCT & active FCT
• One proatherosclerotic mechanism observed for
TMAO in the current studies is suppression of RCT
and promoted accumulation of cholesterol
• Another mechanism by which TMAO may promote
atherosclerosis is through increasing macrophage
SRA and CD36 surface and thereby potentially
contribute to enhanced “forward cholesterol
transport.”
• Reducing synthesis of bile acids from cholesterol,
and decreasing expression of bile acid transporters
in the liver

46. Will be continued by Dr. Ahmadi & me…….

47. Lactobacillus spp
• casei spp (Rhamnosus, DN..)
• reuteri
• acidophilus
• shirota
• delbrueckii, sp. Bulgaricus
• brevis
• plantarum
Bifidobacterium spp
• bifidum
• infantum
• longum
• thermophilum
• lactis
PROBIOTICS:
classification
Cocci gram-positive
• Streptococcus thermophilus
• Enterococcus faecium
• Streptococcus intermedieus
• Streptococcus alfa-emoliticus
Bacillus gram-negative
• Escherichia coli Nissle (1917)
Guarino A. Bruzzese E. 2001; FAO/WHO,
Bacillus gram-positive
• Bacillus clausii
Yeast
• Saccharomyces boulardii

48. Need for a Strain Specific
Microbial Therapy
Different action for each Probiotic:
Knowledge of microorganism functions and host genetic
modulation by different Species/Strain is crucial

49. ..waiting NEXT GENERATION
PROBIOTICS
1. Faecalibacterium prausnitzii
2. Akkermansia muciniphila
3. Eubacterium halii
4. …

52. Possible project in 2016?
Dr. Saghiri will say…

53. Future lecture: The microbiota communicates with the brain
The intestine communicates with the brain through the gut-brain axis, a network involving the CNS and the IS.
Signals run along this axis in a bidirectional way carrying. Homeostatic messages originated by hormonal, neural and
immunological stimuli. The microbiota modulates this mechanism producing metabolites capable of altering the
functions of the CNS and the IS. It has been observed that the microbiota in the human intestine has an important
role in the regulation of anxiety, depression, pain, mood and cognition. Examples of some bacteria that produce
neurotransmitters and neuromodulators are Escherichia sp., Bacillus sp., and Saccharomyces sp. (noradrenaline),
Candida sp., Streptococcus sp., Escherichia sp. and Enterococcus sp. (serotonin), Bacillus sp. (dopamine), and
Lactobacillus sp. (acetylcholine).

54. 3 rd World Congress on Targeting Microbiota 2015
which held at Pasteur Institute In Paris, France from
October 21-23, 2015

55. Thanks for your attention