Smad3 knock-out mice as a useful model to study intestinal fibrogenesis.
OBJECTIVE
To evaluate the possible differences in morphology and immunohistochemical expression of CD3, transforming growth factor beta1 (TGF-beta1), Smad7, alpha-smooth muscle actin (alpha-Sma), and collagen types I-VII of small and large intestine in Smad3 null and wild-type mice.


METHODS
Ten null and ten wild-type adult mice were sacrificed at 4 mo of age and the organs (esophagus, small and large bowel, ureters) were collected for histology (hematoxylin and eosin, Masson thrichrome, silver staining), morphometry and immunohistochemistry analysis. TGF-beta1 levels of intestinal tissue homogenates were assessed by ELISA.


RESULTS
No macroscopic intestinal lesions were detected both in null and wild-type mice. Histological and morphometric evaluation revealed a significant reduction in muscle layer thickness of small and large intestine in null mice as compared to wild-type mice. Immunohistochemistry evaluation showed a significant increase of CD3+ T cell, TGF-beta1 and Smad7 staining in the small and large intestine mucosa of Smad3 null mice as compared to wild-type mice. Alpha-Sma and collagen I-VII staining of small and large intestine did not differ between the two groups of mice. TGF-beta1 levels of colonic tissue homogenates were significantly higher in null mice than in wild-type mice. In preliminary experiments a significant reduction of TNBS-induced intestinal fibrosis was observed in null mice as compared to wild-type mice.


CONCLUSIONS
Smad3 null mice are a useful model to investigate the in vivo role of the TGF-beta/Smad signalling pathway in intestinal inflammation and fibrosis.
Università degli Studi di L'Aquila, Italy.
Giuliana
G
Zanninelli
Antonella
A
Vetuschi
Roberta
R
Sferra
Angela
A
D'Angelo
Amato
A
Fratticci
Maria Adelaide
MA
Continenza
Maria
M
Chiaramonte
Eugenio
E
Gaudio
Renzo
R
Caprilli
Giovanni
G
Latella
D000199:Actins / Q000032:analysis; D000818:Animals; D017252:CD3 Complex / Q000032:analysis; D003094:Collagen / Q000032:analysis; D004247:DNA / Q000032:analysis; D004195:Disease Models, Animal; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D005355:Fibrosis / Q000473:pathology / Q000503:physiopathology; D007113:Immunity, Innate / Q000235:genetics / Q000502:physiology; D007150:Immunohistochemistry; D007413:Intestinal Mucosa / Q000737:chemistry / Q000473:pathology / Q000502:physiology; D007420:Intestine, Large / Q000737:chemistry* / Q000473:pathology* / Q000502:physiology; D007421:Intestine, Small / Q000737:chemistry* / Q000473:pathology* / Q000502:physiology; D008297:Male; D051379:Mice; D018345:Mice, Knockout; D009130:Muscle, Smooth / Q000737:chemistry; D010641:Phenotype; D016133:Polymerase Chain Reaction; D015398:Signal Transduction / Q000502:physiology; D051900:Smad3 Protein / Q000235:genetics* / Q000502:physiology; D051906:Smad7 Protein / Q000032:analysis; D016212:Transforming Growth Factor beta / Q000032:analysis / Q000502:physiology; D053773:Transforming Growth Factor beta1
D000199:Actins; D017252:CD3 Complex; D051900:Smad3 Protein; C497791:Smad3 protein, mouse; D051906:Smad7 Protein; C497807:Smad7 protein, mouse; C508961:Tgfb1 protein, mouse; D016212:Transforming Growth Factor beta; D053773:Transforming Growth Factor beta1; D003094:Collagen; D004247:DNA