Pkd1l1-deficiency drives biliary atresia through ciliary dysfunction in biliary epithelial cells.

BACKGROUND & AIMS: Syndromic biliary atresia is a cholangiopathy characterized by fibro-obliterative changes in the extrahepatic bile duct (EHBD) and congenital malformations including laterality defects. The etiology remains elusive and faithful animal models are lacking. Genetic syndromes provide important clues regarding the pathogenic mechanisms underlying the disease. We investigated the role of the gene Pkd1l1 in the pathophysiology of syndromic biliary atresia. METHODS: Constitutive and conditional Pkd1l1 knockout mice were generated to explore genetic pathology as a cause of syndromic biliary atresia. We investigated congenital malformations, EHBD and liver pathology, EHBD gene expression, and biliary epithelial cell turnover. Biliary drainage was functionally assessed with cholangiography. Histology and serum chemistries were assessed after DDC (3,5-diethoxycarbony l-1,4-dihydrocollidine) diet treatment and inhibition of the ciliary signaling effector GLI1. RESULTS: Pkd1l1-deficient mice exhibited congenital anomalies including malrotation and heterotaxy. Pkd1l1-deficient EHBDs were hypertrophic and fibrotic. Pkd1l1-deficient EHBDs were patent but displayed delayed biliary drainage. Pkd1l1-deficient livers exhibited ductular reaction and periportal fibrosis. After DDC treatment, Pkd1l1-deficient mice exhibited EHBD obstruction and advanced liver fibrosis. Pkd1l1-deficient mice had increased expression of fibrosis and extracellular matrix remodeling genes (Tgfα, Cdkn1a, Hb-egf, Fgfr3, Pdgfc, Mmp12, and Mmp15) and decreased expression of genes mediating ciliary signaling (Gli1, Gli2, Ptch1, and Ptch2). Primary cilia were reduced on biliary epithelial cells and altered expression of ciliogenesis genes occurred in Pkd1l1-deficient mice. Small molecule inhibition of the ciliary signaling effector GLI1 with Gant61 recapitulated Pkd1l1-deficiency. CONCLUSIONS: Pkd1l1 loss causes both laterality defects and fibro-proliferative EHBD transformation through disrupted ciliary signaling, phenocopying syndromic biliary atresia. Pkd1l1-deficient mice function as an authentic genetic model for study of the pathogenesis of biliary atresia. IMPACT AND IMPLICATIONS: The syndromic form of biliary atresia is characterized by fibro-obliteration of extrahepatic bile ducts and is often accompanied by laterality defects. The etiology is unknown, but Pkd1l1 was identified as a potential genetic candidate for syndromic biliary atresia. We found that loss of the ciliary gene Pkd1l1 contributes to hepatobiliary pathology in biliary atresia, exhibited by bile duct hypertrophy, reduced biliary drainage, and liver fibrosis in Pkd1l1-deficient mice. Pkd1l1-deficient mice serve as a genetic model of biliary atresia and reveal ciliopathy as an etiology of biliary atresia. This model will help scientists uncover new therapeutic approaches for patients with biliary atresia, while pediatric hepatologists should validate the diagnostic utility of PKD1L1 variants.

Synchronous visceral Kaposi sarcoma and extracavitary primary effusion lymphoma in a patient with AIDS.

While infection should always lead the differential when a patient with AIDS presents with fever, inflammatory and malignant aetiologies should also be considered. With profound immunocompromise, malignancies can develop as sequelae of viral oncogene expression. Human herpesvirus 8 (HHV-8) infection drives several AIDS-related cancers including Kaposi sarcoma (KS), multicentric Castleman disease and primary effusion lymphoma (PEL), which can present simultaneously with variable clinical features. Herein, we describe a case of synchronous visceral KS and extracavitary PEL in a patient with AIDS. The patient was treated with systemic chemotherapy and remains in remission after four cycles. We review other cases of copresenting HHV-8-related malignancies, explore the salient pathomechanisms and clinical features of these cancers and discuss treatment strategies.

The Use of Smoothelin and Other Antibodies in the Diagnosis of Uterine and Soft Tissue Smooth Muscle Tumors.

Smoothelin is a cytoplasmic protein expressed in differentiated smooth muscle cells. Immunohistochemical evaluation of smoothelin has previously been reported in gastrointestinal (GI) smooth muscle tumors, but has yet to be studied in smooth muscle tumors of uterine and other soft tissue origin. DOG1 expression is reported to be specific for GI stromal tumors; however, variable expression has been reported in leiomyosarcomas (LMS) depending on site of origin. Overexpression of p16 is common in LMS of uterine and other sites of origin, but has not been correlated with tumor grade. This study explores the differential expression of these markers, as well as caldesmon, in LMS cases to assess diagnostic utility. Using tissue microarrays and cases from Tulane Medical Center and Medical College of Wisconsin, expression of smoothelin, DOG1, caldesmon, and p16 was evaluated by immunohistochemistry in 87 cases of LMS. The cases were subdivided by location of origin into uterine (N=31) and nonuterine (N=56) with 10 of the nonuterine of GI origin, as well as by grade into low grade (N=27) and intermediate and high grade (N=60). Differential expression among different grades and locations was evaluated. The same markers were evaluated in atypical leiomyoma cases (N=4) and 1 smooth muscle tumor of uncertain malignant potential case (N=1). Smoothelin expression was also assessed in 20 benign uterine leiomyomas. Weak DOG1 expression is rare but possible in extrauterine LMS. Expression of p16 is common in both uterine and extrauterine LMS, and more frequent in higher grades. Expression of smoothelin in this study differed depending on tumor type, grade, and site of origin. All leiomyomas and most atypical leiomyomas showed cytoplasmic positivity for smoothelin, whereas only 5% of LMS had cytoplasmic expression. The study suggests smoothelin may be downregulated in the cytoplasm of malignant smooth muscle tumor cells and may serve as a supportive aid in the distinction of LMS from benign smooth muscle tumors in cases where it is difficult by morphology alone.

Thermodynamic profiles of salt effects on a host-guest system: new insight into the Hofmeister effect.

Isothermal titration calorimetry was used to probe how salts influence the thermodynamics of binding of guests to cavitand 1. Studies involved six Hofmeister salts covering the range of salting-in to strongly salting-out. The latter were found to reduce affinity. The cause of this was competitive binding of the weakly solvated anion to the hydrophobic pocket of the host. At the other extreme of the Hofmeister series, salts increased guest affinity. Two factors for this were evident. At low concentrations the data fitted a previously reported model that accounts for cation condensation to the outer carboxylates of the host (Carnagie, R.; Gibb, C. L. D.; Gibb, B. C., Angew. Chem., Int. Ed. 2014, 53 (43), 11498-11500). At higher concentrations, an as of yet unidentified contribution was observed that was noted to be guest dependent. Midcontinuum salts such as NaClO3 were found to enhance affinity at low concentrations, but weaken it at high concentrations; a nonmonotonic trend attributed to the aforementioned competing phenomena. In combination with previous work, the data presented here reveal that the Hofmeister effect evident in this system can be mostly attributed to solute-salt interactions.