Pizza Club-

GUT MICROBIOME–DERIVED METABOLITES MODULATE INTESTINAL EPITHELIAL CELL DAMAGE AND MITIGATE GRAFT-VERSUS-

HOST DISEASE

Mathewson et al.

2016 Nature Immunology 17(5):505-513.

25.05.2016 Anne Kaysen

2

Background - Microbiome

… a whole microbial ecosystemBacteriaArchaea

EukaryotesViruses

• Development and maintenance of the immune system

• Induction of IgA production

Immune functions• Ferment non-digestible

oligosaccharides ( SCFA)• Ion absorption• Metabolism of xenobiotics• Synthesis of several vitamins

Metabolic functions• Prevention of overgrowth by

potential pathogens• Pathogen displacement• Nutrient competition• Production of anti-microbial

factors

Protective functions

Modified from: O’Hara & Shanahan. EMBO Rep (2006), 7(7):688-693. Important role in human health and disease

2

Modified from: O’Hara & Shanahan. EMBO Rep (2006), 7(7):688-693.

Allogeneic stem cell transplantation

Graft-versus host disease: Donor-derived immune cells target the patient’s tissues

4

Background – what is known?

Intestinal microbiota composition is altered after allogeneic stem cell transplantation in patients with graft-versus-host disease

Alterations correlate with graft-versus-host disease severity

5

Background – Open questions?

Direct causality between changes in host microbiota and GvHD severity is unclear.

Microbiota community structure changes – microbial-derived metabolites?

Changes in microbial metabolites – effect on outcome after allogeneic stem cell transplantation

6

Experimental setup

3 groups of mice naïve mice – no BMT

syngeneic BMT (same strain of mice) BALB/c→BALB/c or C57BL/6J→C57BL/6J in humans: donor – identical twin GvHD rare and usually not severe

allogeneic BMT (different strains of mice) C57BL/6J→BALB/c in humans: ideally a matched donor

Donor Recipient

7

Experimental setup

3 groups of mice naïve mice – no BMT

syngeneic BMT (same strain of mice) BALB/c→BALB/c or C57BL/6J→C57BL/6J in humans: donor – identical twin GvHD rare and usually not severe

allogeneic BMT (different strains of mice) C57BL/6J→BALB/c in humans: ideally a matched donor

Donor Recipient

8

Do changes in microbiota result in alterations in levels of microbial metabolites?

Does the decrease in butyrate in intestinal epithelial cells have a functional impact?

9

Histone deacetylases Histone acetyltransferase

What functional impact does the decrease in butyrate in IECs have?

Butyrate is an important histone deacetylase inhibitor

Reduction of histone acetylation in IECs is a result of decreased amounts of butyrate.

Lower level of butyrate in IECs due to impaired uptake?

10

Why is the level of butyrate in IECs decreased? Imparied uptake?

Intense inflammatory mileu after allo-BMT causes decreased expression of butyrate transporters.

Can the level and functional effect of butyrate be restored?

Butyrate transporter Butyrate receptor

11

Restoration of butyrate in IECs and functional effect on histone acetylation

Intragastric gavage

Positive feedback mechanism.

12

Butyrate - effect on GvHD and survival

Body weight GvHD Survival

Butyrate induces GvHD protective effects.

How?

13

Effect of butyrate – improved epithelial integrity?

Transmission electron microscopy Leakage of the electron-dense stain ruthenium

red

Change the gastrointestinal microbiome?

14

Change of GI microbiota – higher butyrate – effect?

16S sequencing Stool IECs

17 strains of Clostridiaday -14 – day 21

15

Conclusion

Butyrate is the only SCFA to decrease significantly in amount after allo-BMT

Significant decrease only in the intestinal tissue

High levels of butyrate (and possibly of specific bacteria) seem to protect from GvHD

Butyrate increases junctional integrity Other effects of butyrate?

16 THANK YOU