title: Integrin β-8, but not β-5 or -6, protein expression is increased in livers of children with biliary atresia.
abstract: OBJECTIVE
  Our previous work demonstrated altered messenger RNA expression of integrin β-5 and -8, using an in silico analysis of publically available data from patients with biliary atresia (BA); however, we were unable to demonstrate statistically significant differences in protein expression because of sample size. In the present study, we repeated the analysis of liver fibrosis and protein expression of the integrins in a larger cohort of patients with BA and compared them with patients undergoing liver biopsy for other diagnoses, with the hypothesis that ≥ 1 of the integrins would be differentially expressed.
  
  
  METHODS
  Liver specimens were obtained at 2 collaborating institutions. Samples from infants with BA (n = 23) were compared with samples from those who underwent liver biopsy for neonatal hepatitis (n = 9). All of the specimens were analyzed by 2 pathologists (C.R. and R.A.), who were blinded to the diagnoses. Standard Ishak scoring was performed to evaluate fibrosis and inflammation, and immunohistochemical (IHC) positivity was graded from 0 to 4. Comparisons between the IHC positivity and Ishak scoring for the BA and control groups were performed using the Student t test with P < 0.01 considered significant because of the multiple comparisons. Interobserver variability was assessed by intraclass correlation (ICC).
  
  
  RESULTS
  Pooled analysis from specimens from patients with BA showed significantly more fibrosis than controls based on Ishak scores (3.21 ± 1.82 vs 1.17 ± 1.00, P < 0.005). IHC evaluation showed increased integrin ανβ8 protein expression when compared with controls (2.67 ± 0.81 vs 1.72 ± 0.62, P < 0.005); however, there were no significant differences in integrin ανβ5 (1.93 ± 0.84 vs 1.50 ± 0.90, P = 0.23) or integrin ανβ6 (0.85 ± 1.20 vs 0.94 ± 0.85, P = 0.82) expression. These data were confirmed on individual analysis. Interobserver agreement was fair for integrin ανβ5 (ICC 0.52), good for integrin ανβ6 (ICC 0.72), and excellent for integrin ανβ8 (ICC 0.79) and fibrosis (ICC 0.89).
  
  
  CONCLUSIONS
  Our data show that integrin ανβ8, but not integrin ανβ5 or integrin ανβ6, protein expression is increased in liver specimens of patients with BA. These data support the mounting evidence that transforming growth factor-β (TGF-β) activation is responsible for the fibrosis found in BA. Anti-integrin ανβ8 or more global integrin blocking strategies may be therapeutic options in BA, but further work is clearly needed.
authors: *Sheikh Zayed Institute for Pediatric Surgical Innovation †Department of Pathology ‡Department of Gastroenterology, Hepatology, and Nutrition, Children's National Medical Center, Washington, DC §Division of Pediatric Gastroenterology and Nutrition ||Department of Pathology, Johns Hopkins School of Medicine, Baltimore, Maryland.
authors: Tatiana
authors: T
authors: Iordanskaia
authors: Emily
authors: E
authors: Koeck
authors: Christopher
authors: C
authors: Rossi
authors: Parvathi
authors: P
authors: Mohan
authors: Kathleen
authors: K
authors: Schwarz
authors: Robert
authors: R
authors: Anders
authors: Evan P
authors: EP
authors: Nadler
mesh_terms: D001656:Biliary Atresia / Q000378:metabolism* / Q000473:pathology; D001706:Biopsy; D015870:Gene Expression; D006801:Humans; D007150:Immunohistochemistry; D007231:Infant, Newborn; D039641:Integrin beta Chains / Q000235:genetics* / Q000378:metabolism; D008099:Liver / Q000737:chemistry* / Q000473:pathology; D008103:Liver Cirrhosis / Q000378:metabolism / Q000473:pathology; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D016212:Transforming Growth Factor beta / Q000235:genetics / Q000502:physiology
chemical_list: D039641:Integrin beta Chains; D012333:RNA, Messenger; D016212:Transforming Growth Factor beta; C084344:integrin beta5; C072170:integrin beta6; C094865:integrin beta8