Research Spotlight

Posted July 15th 2017

Non-HLA Antibodies Impact on C4d staining, Stellate Cell Activation and Fibrosis in Liver Allografts.

Göran Klintmalm M.D.

Göran Klintmalm M.D.

O’Leary, J. G., A. J. Demetris, A. Philippe, R. Freeman, J. Cai, H. Heidecke, C. Smith, B. Hart, L. W. Jennings, R. Catar, M. Everly, G. B. Klintmalm and D. Dragun (2017). “Non-hla antibodies impact on c4d staining, stellate cell activation and fibrosis in liver allografts.” Transplantation: 2017 Jun [Epub ahead of print].

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BACKGROUND: Recent data has shown an increased risk for rejection, fibrosis progression, and death in liver transplant (LT) recipients with preformed or de novo HLA donor-specific alloantibodies (DSA). However, the role of non-HLA autoantibodies and the interaction between HLA DSA and non-HLA autoantibodies remains uncharacterized. METHODS: We analyzed 1269 primary LT recipients from 1/2000-4/2009 with known HLA DSA status for Angiotensin II Type-1 Receptor and Endothelin-1 Type A receptor autoantibodies(anti-AT1R-Abs and anti-ETAR-Abs respectively) pre-LT and year-1 post-LT. RESULTS: Preformed non-HLA autoantibodies alone did not impact outcomes. In multivariable modeling, the combination of preformed non-HLA autoantibodies and HLA-DSA were associated with an increased risk for death [Hazard Ratio (HR)=1.66; p=0.02] especially if the HLA DSA was of the IgG3 subclass (HR=2.28; p=0.01). A single de novo non-HLA autoantibody was associated with an increased risk for TCMR or AMR rejection(68% vs. 41%, p=0.01) and fibrosis progression (HR=1.84; p=0.02). Biopsies with de novo non-HLA autoantibodies revealed a new sinusoidal C4d staining pattern when compared to HLA DSA(71% vs. 3%; p<0.001). Liver sinusoidal endothelial cell(LSEC) activation and stellate cell activation was increased in patients with non-HLA autoantibodies in the location of C4d positivity. CONCLUSIONS: A non-HLA autoantibody combined with a preformed HLA DSA is associated with an increased mortality risk. Isolated de novo anti-AT1R-Abs and/or anti-ETAR-Abs are associated with an increased risk of rejection and fibrosis progression. The novel location of C4d staining in proximity to LSEC capillarization and stellate cell activation demonstrates allograft injury in proximity to non-HLA autoantibody binding.


Posted July 15th 2017

The Hippo signaling functions through the Notch signaling to regulate intrahepatic bile duct development in mammals.

Sharon DeMorrow Ph.D.

Sharon DeMorrow Ph.D.

Wu, N., Q. Nguyen, Y. Wan, T. Zhou, J. Venter, G. A. Frampton, S. DeMorrow, D. Pan, F. Meng, S. Glaser, G. Alpini and H. Bai (2017). “The hippo signaling functions through the notch signaling to regulate intrahepatic bile duct development in mammals.” Lab Invest 97(7): 843-853.

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The Hippo signaling pathway and the Notch signaling pathway are evolutionary conserved signaling cascades that have important roles in embryonic development of many organs. In murine liver, disruption of either pathway impairs intrahepatic bile duct development. Recent studies suggested that the Notch signaling receptor Notch2 is a direct transcriptional target of the Hippo signaling pathway effector YAP, and the Notch signaling is a major mediator of the Hippo signaling in maintaining biliary cell characteristics in adult mice. However, it remains to be determined whether the Hippo signaling pathway functions through the Notch signaling in intrahepatic bile duct development. We found that loss of the Hippo signaling pathway tumor suppressor Nf2 resulted in increased expression levels of the Notch signaling pathway receptor Notch2 in cholangiocytes but not in hepatocytes. When knocking down Notch2 on the background of Nf2 deficiency in mouse livers, the excessive bile duct development induced by Nf2 deficiency was suppressed by heterozygous and homozygous deletion of Notch2 in a dose-dependent manner. These results implicated that Notch signaling is one of the downstream effectors of the Hippo signaling pathway in regulating intrahepatic bile duct development.


Posted July 13th 2017

Prolonged darkness reduces liver fibrosis in a mouse model of primary sclerosing cholangitis by miR-200b down-regulation.

Gianfranco D. Alpini Ph.D.

Gianfranco D. Alpini Ph.D.

Wu, N., F. Meng, T. Zhou, Y. Han, L. Kennedy, J. Venter, H. Francis, S. DeMorrow, P. Onori, P. Invernizzi, F. Bernuzzi, R. Mancinelli, E. Gaudio, A. Franchitto, S. Glaser and G. Alpini (2017). “Prolonged darkness reduces liver fibrosis in a mouse model of primary sclerosing cholangitis by mir-200b down-regulation.” Faseb j: 2017 Jun [Epub ahead of print].

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Melatonin therapy or prolonged exposure to complete darkness reduces biliary hyperplasia and liver fibrosis in bile-duct-ligated (BDL) rats; however, no information exists in primary sclerosing cholangitis (PSC). Thus, we aimed to determine the therapeutic effects of prolonged dark therapy or melatonin administration on hepatic fibrosis in the Mdr2-/- mouse model of PSC. Melatonin levels, biliary mass, liver fibrosis, angiogenesis and miR-200b expression were evaluated in wild-type and Mdr2-/- mice exposed to darkness or melatonin treatment or in male PSC patient samples and healthy controls. Mdr2-/- mice were also treated with miR-200b inhibitor or control before evaluating biliary mass, liver fibrosis, and angiogenesis. After overexpression of arylalkylamine N-acetyltransferase (AANAT; the enzyme regulating melatonin synthesis) or inhibition of miR-200b in cholangiocytes and hepatic stellate cells in vitro, we evaluated angiogenesis and fibrosis gene expression. After exposure to darkness or administration of melatonin, Mdr2-/- mice show elevated serum melatonin levels and inhibition of biliary mass, along with reduction of liver fibrosis and angiogenesis. miRNA PCR analysis demonstrated that miR-200b expression increased in Mdr2-/- mice and PSC patient samples compared with controls and decreased in Mdr2-/- mice subjected to dark exposure or melatonin treatment. Inhibition of miR-200b in Mdr2-/- ablates biliary proliferation, liver fibrosis, and angiogenesis. In vitro, overexpression of AANAT or inhibition of miR-200b in cholangiocytes and hepatic stellate cells decreased the expression of miR-200b, angiogenesis, and fibrosis genes. Dark therapy or targeting melatonin/miR-200b axis may be important in the management of biliary damage and liver fibrosis in cholangiopathies including PSC.-Wu, N., Meng, F., Zhou, T., Han, Y., Kennedy, L., Venter, J., Francis, H., DeMorrow, S., Onori, P., Invernizzi, P., Bernuzzi, F., Mancinelli, R., Gaudio, E., Franchitto, A., Glaser, S., Alpini G. Prolonged darkness reduces liver fibrosis in a mouse model of primary sclerosing cholangitis by miR-200b down-regulation.


Posted July 13th 2017

The effects of hip abduction on sciatic nerve biomechanics during terminal hip flexion.

Hal David Martin D.O.

Hal David Martin D.O.

Martin, H. D., A. N. Khoury, R. Schroder, J. Gomez-Hoyos, S. Yeramaneni, M. Reddy and I. James Palmer (2017). “The effects of hip abduction on sciatic nerve biomechanics during terminal hip flexion.” J Hip Preserv Surg 4(2): 178-186.

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Terminal hip flexion contributes to increased strain in peripheral nerves at the level of the hip joint. The effects of hip abduction and femoral version on sciatic nerve biomechanics are not well understood. A decrease in sciatic nerve strain will be observed during terminal hip flexion and hip abduction, independent of femoral version. Six un-embalmed human cadavers were utilized. Three Differential Variable Reluctance Transducers (DVRTs) sensors were placed on the sciatic nerve while the leg was flexed to 70 degrees with a combination of – 10 degrees , 0 degrees , 20 degrees and 40 degrees adduction/abduction. DVRT placement included: (i) under piriformis, (ii) immediately distal to the gemelli/obturator, (iii) four centimeters distal to sensor two. A de-rotational osteotomy to decrease femoral version 10 degrees was performed, and sciatic nerve strain was measured by the same procedure. Data were analyzed with three-way analysis of variance and Bonferroni post-hoc analysis to identify differences in the mean values of sciatic nerve strain between native and decreased version state, hip abduction angle and DVRT sensor location. Significant main effects were observed for femoral version (P = 0.04) and DVRT sensor location (P = 0.01). Sciatic nerve strain decreased during terminal hip flexion and abduction in the decreased version state. An 84.23% decrease in sciatic nerve strain was observed during hip abduction from neutral to 40 degrees in the presence of decreased version at terminal hip flexion. The results obtained from this study confirm the role of decreased femoral version and hip abduction at terminal hip flexion to decrease the strain in the sciatic nerve.


Posted June 15th 2017

Importance of endogenous compensatory vasoactive peptides in broadening the effects of inhibitors of the renin-angiotensin system for the treatment of heart failure.

Milton Packer M.D.

Milton Packer M.D.

Packer, M. and J. J. V. McMurray (2017). “Importance of endogenous compensatory vasoactive peptides in broadening the effects of inhibitors of the renin-angiotensin system for the treatment of heart failure.” Lancet 389(10081): 1831-1840.

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The magnitude of the clinical benefits produced by inhibitors of the renin-angiotensin system in heart failure has been modest, possibly because of the ability of renin-angiotensin activity to escape from suppression during long-term treatment. Efforts to intensify pharmacological blockade by use of dual inhibitors that interfere with the renin-angiotensin system at multiple sites have not yielded consistent incremental clinical benefits, but have been associated with serious adverse reactions. By contrast, potentiation of endogenous compensatory vasoactive peptides can act to enhance the survival effects of inhibitors of the renin-angiotensin system, as evidenced by trials that have compared angiotensin-converting enzyme inhibitors with drugs that inhibit both the renin-angiotensin system and neprilysin. Several endogenous vasoactive peptides act as adaptive mechanisms, and their augmentation could help to broaden the benefits of renin-angiotensin system inhibitors for patients with heart failure.