Therapeutic options to modulate intestinal barrier

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1 min J.D. Schulzke Dept. of General Medicine Therapeutic options to modulate intestinal barrier

2 What makes up epithelial barrier function? ions/h 2 O antigens/bacteria tight junction apoptoses erosions ulcer transcytosis

3 Crohn s disease (CD) erosion ulcers mild inflammation severe inflammation Lesions: are sites of elevated leakiness!

4 Tight junctions in crohn s disease crohn 24 Claudins Occludin

5 Tight junctions TJ strands 7.2 ± 0.2 strand discontinuities (per 1 μm strand length) 0.2 ± 0.1 n 6 in crohn s disease crohn 4.7 ± ± P <0.001 <0.001 crohn

6 Tight junction proteins in crohn s disease Crohn's disease occludin claudin-1 claudin-2 claudin-3 claudin-4 claudin-5 claudin-7 claudin-8 64 kd 22 kd 22 kd 22 kd 22 kd 22 kd 22 kd 22 kd - claudin-2 - claudin-5 - claudin-8

7 LSM of tight junction proteins in crohn s disease pore-forming claudin-2 claudin-2 CD claudin-3 TJ strands claudin-5 sealing claudin-5 and -8 Pore-forming claudin-2 appears Sealing claudin -55 and 8: expression distributed off the TJ claudin-8

8 Apoptotic rate in crohn s disease TUNEL n 1.9 ± 0.2 % 10 crohn 5.2 ± 0.5 % 10 crohn P <0.001

Epithelial apoptoses are leaks conductance

non-apoptotic area non-apoptotic epithelium

9 Epithelial apoptoses are leaks conductance scanning conductance probe preamp apical epithelial monolayer basal Gitter FASEB J.1999;14: Current density non-apoptotic area non-apoptotic epithelium distance from center of rosette [µm]

10 Antigen-uptake in crohn s disease Söderholm et al, Gastroenterology 1999; 117: N N ovalbumin dextran 40,000 merge inactive CD perpetuates inflammation precedes acute inflammatory transcytosis attacks

11 Are there a therapeutic options for barrier disturbances? yes! anti-inflammatory therapy important TNFα antibody (remicade ) barrier-affecting agents effect in IBD? L-glutamine probiotics TGF-β zinc flavonoids (quercetin)

12 TNFα Ab (infliximab, remicade ) A B A repair of epithelial barrierfunction Zeissig et al, Gut 2004; 53: B downregulation of epithelial apoptoses

13 TNFα antibodies (infliximab, remicade ) do not influence the tight junction proteins after 14 days! Zeissig et al, Gut 2004; 53:

14 TNFα causes immune cell apoptosis before infliximab 14 d after infliximab leading to reduced effector cytokine release (epithelial damage )

0 Injured HT-29/B6 monolayers (scraping) occludin claudin-1 1 2 3 4 5

15 IL-13 is key effector cytokine in ulcerative colitis Heller 2005 Gastroenterology 129: IL Injured HT-29/B6 monolayers (scraping) occludin claudin kd 22 kd V μm/h *** claudin-2 22 kd 5. 0 claudin-4 22 kd 0. 0 IL-13 ulcerative colitis

16 Barrier affecting agents

17 L-Glutamine Barrier influencing effects? is metabolized by enterocytes (important fuel) may influence tight junctions? may have anti-apoptotic effects on enterocytes? may inhibit transcytotic events

18 L-Glutamine improves barrier properties in animal models E. coli translocation is reduced by glutamine-feeding to mice in a skin burn model (Gennari & Alexander Crit Care Med 25: ). The increase in the lactulose/ mannitol-ratio by TPN in rats is antagonized by 2% glutamine-supplementation (Li et al JPEN 18: ). there is no significant effect in crohn s disease in crohn s patients under TPN with glutamine-therapy (Akobeng et al J Ped Gastr Nutr 30: 78-84) or in crohn s patients under long term oral glutaminetherapy (Den Hond et al J Parenter Enteral Nutr 23:7-11).

19 Probiotics can stabilize epithelial barrier in animal and cell models also Saccharomyces boulardii stabalizes barrier function in T84 infected with enteropathogenic E. coli (Czebrucka et al. Inf Imm 2000; 68: ). VSL3 reduces salmonella invasion in T84 (Madsen et al. Gastroenterology 2001; 121: ). Lactobazillus attenuates the aspirin-induced tight junctiondefect in HT-29 (Montalto et al. Digestion 2004; 69: 225-8). can keep UC in remission (E. coli Nissle 1917) and normalize barrier function in IL-10 deficient mice There is no evidence for a barrier effect in IBD!

20 Transforming growth factor TGF-β improves barrier properties in epithelial cell models TGFβ stabalizes resistance in T84 after interferon-γ (Plachon et al. J Immunol 1994; 153: ). TGFβ accelerates epithelial restitution in T84 (McKaig et al. Am J Physiol 1999; 276: G ). TGFβ improves barrier function in E. coli O157:H7- exposed T84 accompanied by tight junction effects (Howe et al. Am J Pathol 2005; 167: ). there is no evidence for an effect in crohn s disease

21 Zinc lactulose/mannitol-ratios are improved in 12 crohn s patients from to by zinc (3*110 mg per day) (Sturniolo et al. IBD 2001; 7: 94-8). The mechanisms are not clear: changes in villus and tj structure? (only in deficiency?) clinical relevance of zinc is still controversely discussed

22 Quercetin Flavonoid (onion, apple ) Flavan O % of initial resistance *** *** *** C Q * quercetin time (hours) Caco-2 cells Maren Amasheh et al., 2008, J. Nutr. 138:

Effect of quercetin 350 300 * quercetin claudin-4 mrna (%) 250 200 150 100

23 Effect of quercetin * quercetin claudin-4 mrna (%) quercetin 200 * C4P activity (%) quercetin (µmol/l)

24 IF confocals of claudin-4 4 in Caco-2 quercetin

25 Summery Barrier function is impaired in IBD, due to transcytosis, TJs, apoptotic rate and epithel lesions, which contribute to inflammation (Ag-uptake) and to diarrhea (leak flux-mechanism). Barrier therapy is most efficient by antiinflammatory remedies (e.g. infliximab), but barrier preserving properties are observed also for L-glutamine, probiotics, TGFβ, zinc and flavonoids which need further investigation in IBD.

Probiotics the Good Neighbor: Guarding the Gut Mucosal Barrier

American Journal of Infectious Diseases 5 (3): 188-192, 2009 ISSN 1553-6203 2009 Science Publications Probiotics the Good Neighbor: Guarding the Gut Mucosal Barrier R.K. Rao, D.B. Polk, A. Seth and F.