Predictors of biliary atresia outcome: Saudi National Study (2000 - 2018).

Background: Outcomes in biliary atresia (BA) have been well-documented in large national cohorts from Europe, North America, and East Asia. Understanding the challenges that preclude success of the Kasai portoenterostomy (KPE) is the key to improve the overall outcomes of BA and implementing intervention strategies. Here, we analyzed the data from the Saudi national BA study (204 BA cases diagnosed between 2000 and 2018) to identify the prognostic factors of BA outcomes. Methods: One hundred and forty-three cases underwent KPE. Several prognostic factors (center case load, congenital anomalies, serum gamma-glutamyl transferase, use of steroids, ascending cholangitis post-operatively, and degree of portal fibrosis at time of KPE) were investigated and correlated with the primary outcomes of interest: 1) success of KPE (clearance of jaundice and total serum bilirubin <20 mmol/l after KPE), 2) survival with native liver (SNL), and 3) overall survival. Results: Use of steroids after KPE was associated with clearance of jaundice, 68% vs. 36.8% in the BA cases that did not receive steroids (P = 0.013; odds ratio 2.5) and a significantly better SNL rate at 2 - and 10-year of 62.22% and 57.77% vs. 39.47% and 31.57%, respectively (P = 0.01). A better 10-year SNL was observed in centers with caseload <1/year (group 1) as compared to centers that performed ≥1/year (group 2) [45.34% vs. 26.66%, respectively; P = 0.047]. On comparison of the 2 groups, cases in group 1 had KPE at significantly earlier age (median 59.5 vs. 75 days, P = 0.006) and received steroids after KPE more frequently than group 2 (69% vs. 31%, P < 0.001). None of the remaining prognostic variables were identified as being significantly related to BA outcome. Conclusion: Steroids use post-KPE predicted clearance of jaundice and better short- and long-term SNL. There is a need to establish a national BA registry in Saudi Arabia aiming to standardize the pre- and post-operative clinical practices and facilitate clinical and basic research to evaluate factors that influence BA outcome.

Modulation of matrix mineralization by Vwc2-like protein and its novel splicing isoforms.

In search of new cysteine knot protein (CKP) family members, we found a novel gene called von Willebrand factor C domain-containing protein 2-like (Vwc2l, also known as Brorin-like) and its transcript variants (Vwc2l-1, Vwc2l-2 and Vwc2l-3). Based on the deduced amino acid sequence, Vwc2l-1 has a signal peptide and 2 cysteine-rich (CR) domains, while Vwc2l-2 lacks a part of 2nd CR domain and Vwc2l-3 both CR domains. Although it has been reported that the expression of Brorin-like was predominantly observed in brain, we found that Vwc2l transcript variants were detected in more ubiquitous tissues. In osteoblasts, the induction of Vwc2l expression was observed at matrix mineralization stage. When Vwc2l was stably transfected into osteoblasts, the matrix mineralization was markedly accelerated in Vwc2l-expressing clones compared to that in the control, indicating the modulatory effect of Vwc2l protein on osteoblastic cell function. The mechanistic insight of Vwc2l-modulation was further investigated and we found that the expression of Osterix, one of the key osteogenic markers, was significantly increased by addition of all Vwc2l isoform proteins. Taken together, Vwc2l is a novel secreted protein that promotes matrix mineralization by modulating Osterix expression likely through TGF-ß superfamily growth factor signaling pathway. Our data may provide mechanistic insights into the biological functions of this novel CKP member in bone and further suggest a novel approach to enhance osteoblast function, which enables to accerelate bone formation, regeneration and healing.