ARTICLE | doi:10.20944/preprints202102.0335.v1
Subject: Biology, Anatomy & Morphology Keywords: IQGAP1; MST2; LATS1, YAP1, Hippo, Bile acid, hepatocellular carcinoma.
Online: 16 February 2021 (14:08:12 CET)
The Hippo pathway regulates a complex signalling network which mediates several biological functions including cell proliferation, organ size and apoptosis. Several scaffold proteins regulate the crosstalk of the members of the pathway with other signalling pathways and play an important role in the diverse output controlled by this pathway. In this study we have identified the scaffold protein IQGAP1 as a novel interactor of the core kinases of the Hippo pathway, MST2 and LATS1. Our results indicate that IQGAP1 scaffolds MST2 and LATS1, supresses their kinase activity, and YAP1-dependent transcription. Additionally, we show that IQGAP1 is a negative regulator of the non-canonical pro-apoptotic pathway and may enable the crosstalk between this pathway and the ERK and AKT signalling modules. Our data also show that bile acids regulate the IQGAP1-MST2-LATS1 signalling module in hepatocellular carcinoma cells which could be necessary for the inhibition of MST2-dependent apoptosis and hepatocyte transformation.
ARTICLE | doi:10.20944/preprints202208.0202.v1
Subject: Medicine & Pharmacology, Nutrition Keywords: blueberries; bile acids; dietary supplements; polyphenols; LC-MS/MS profiling
Online: 10 August 2022 (11:57:59 CEST)
Cholesterol-derived bile acids (BAs) affect numerous physiological functions such as glucose homeostasis, lipid metabolism and absorption, intestinal inflammation and immunity, as well as intestinal microbiota diversity. Diet influences the composition of the BA pool. The present study analyzes the impact of a dietary supplementation with a freeze-dried blueberry powder (BBP) on the fecal BA pool composition. The diet of 11 men and 13 women at risk for metabolic syndrome was supplemented with 50g/day of BBP for 8 weeks, and feces were harvested before (pre) and after (post) BBP consumption. BAs were profiled using liquid chromatography coupled to tandem mass spectrometry. No significant changes in total BAs were detected when comparing pre- vs post-BBP consumption samples. However, post-BBP consumption samples exhibited significant accumulations of glycine-conjugated BAs (p=0.04), glycochenodeoxycholic (p=0.01) and glycoursodeoxycholic (p=0.01) acids, as well as a significant reduction (p=0.03) of the secondary BA levels, when compared to pre-BBP feces (p=0.03). In conclusion, the fecal bileacidome is significantly altered after the consumption of BBP for 8 weeks. While additional studies are needed to fully understand the underlying mechanisms and physiological implications of these changes, our data suggest that the consumption of blueberries can modulate toxic BAs elimination.
ARTICLE | doi:10.20944/preprints202201.0328.v1
Subject: Life Sciences, Biochemistry Keywords: cytochrome oxidase; thyroid hormones; steroid hormones; Bile Acids Binding Site; regulation
Online: 21 January 2022 (13:36:04 CET)
Thyroid hormones regulate tissue metabolism establishing an energy balance in the cell, in particular by affecting oxidative phosphorylation. Their long-term impact is mainly associated with changes in gene expression, while the short-term effects may differ in mechanism. Our work is devoted to short-term effects of hormones T2, T3, and T4 on mitochondrial cytochrome c oxidase (CcO) mediated by a direct contact with the enzyme. The data obtained indicate the existence of two separate sites of CcO interaction with thyroid hormones differing in location, affinity and specificity to hormone binding. It is shown that T3 and T4 but not T2 inhibit oxidase activity of CcO in solution and on membrane preparations with Кi≈100–200 M. In solution, T3 and T4 compete in a 1:1 ratio with the detergent dodecyl-maltoside for binding to the enzyme. Peroxidase and catalase partial activities of CcO are not sensitive to hormones while electron transfer from heme a to the oxidized binuclear center is affected. We believe that T3 and T4 are ligands of the Bile Acid Binding Site found in the 3D structure of CсO by Ferguson-Miller’s group, and hormone induced inhibition is associated with dysfunction of the K- proton channel. Similar conclusion we made recently with regard to steroid-like compounds. It is found that T2, T3, and T4 inhibit superoxide generation by oxidized CcO in the presence of excess Н2О2. Inhibition is characterized by Ki values of 0.3 – 5 M and apparently affects the formation of О2• at the protein surface. The second binding site for thyroid hormones presumably coincides with the point of tight T2 binding on the Va subunit described in the literature.
ARTICLE | doi:10.20944/preprints202006.0204.v1
Subject: Medicine & Pharmacology, Gastroenterology Keywords: Presepsin; Sepsis; Sequential Organ Failure Assessment (SOFA) score; alkaline phosphatase (ALP); Bile
Online: 16 June 2020 (09:43:45 CEST)
Presepsin is a diagnostic and prognostic biomarker of sepsis; however, elevated presepsin levels have also been documented without sepsis. This study aims to retrospectively analyze the laboratory parameters and Sequential Organ Failure Assessment (SOFA) score affecting presepsin levels in 567 patients. Some patients with elevated presepsin levels exhibited renal dysfunction or elevation of biliary enzymes despite a low SOFA score. The univariate regression analysis revealed a close correlation between presepsin levels and SOFA score, serum creatinine (CRE), blood urea nitrogen, and biliary enzymes. In addition, a multivariate regression analysis revealed that SOFA score, alkaline phosphatase (ALP), and CRE independently affected presepsin levels significantly. The analysis of covariance (ANCOVA) revealed that presepsin levels were significantly higher in patients with hepatobiliary disease. Besides, we found that patients who presented with the dilatation of intra- or extrahepatic bile ducts and the elevation of ALP or total bilirubin exhibited remarkable high presepsin levels in the bile. Furthermore, the presepsin production in the liver’s Kupffer cells was established by immunostaining in patients who received surgical liver resection. Overall, this study elucidates that biliary enzymes’ elevation affects presepsin levels, presepsin exists in high concentrations in the bile, and is positive in Kupffer cells.
CASE REPORT | doi:10.20944/preprints202201.0298.v1
Subject: Medicine & Pharmacology, Oncology & Oncogenics Keywords: Checkpoint inhibitors; Immune related adverse events; Cholestasis; Severe ductopenia; Vanishing bile duct syndrome
Online: 20 January 2022 (11:07:21 CET)
Tyrosine kinase inhibitors (TKI) and immune checkpoint inhibitors (ICI) significantly improve the outcomes of patients with advanced clear cell renal cell carcinoma (ccRCC), but high-grade toxicities can occur, particularly during combination therapy. Herein, we report a patient with advanced metastatic ccRCC, who developed grade 4 cholestasis during combined therapy with nivolumab and cabozantinib. After the exclusion of common disorders associated with choles-tasis and a failure of corticosteroids (CS), a liver biopsy was performed that demonstrated severe ductopenia. Consequently, a diagnosis of vanishing bile duct syndrome related to TKI and ICI administration was made, resulting in CS discontinuation and ursodeoxycholic acid administra-tion. After a 7-months follow-up, liver tests had returned to normal values. Immunological studies revealed that our patient had developed robust T-cells and macrophages infiltrates in his lung metastasis, as well as in skin and liver tissues at the onset of toxicities. At the same time, peripheral blood immunophenotyping revealed significant changes in T-cell subsets suggesting their potential role in the pathophysiology of the disease.
ARTICLE | doi:10.20944/preprints202008.0180.v1
Subject: Medicine & Pharmacology, Pediatrics Keywords: biliary atresia; Kasai portoenterostomy; cholangitis; portal hypertension; bile ducts dilatations; native liver survival
Online: 7 August 2020 (09:27:14 CEST)
The prospective study enrolled 144 patients after surgical treatment of biliary atresia in early infancy. We analyze the immediate effectiveness of the surgery and the age-related structure of complications in the up to 16-year follow-up. The immediate 2-year survival rate after the surgery constituted 49.5%. At the time of this writing, 17 of the patients have celebrated their 10th birthdays with good quality of life and no indications for LT. The obtained results underscore the critical importance of surgical correction of BA by Kasai surgery during the first 60 days of life and subsequent dynamic follow-up of the patients for the purpose of the early detection and timely correction of possible complications.
ARTICLE | doi:10.20944/preprints201801.0046.v2
Subject: Medicine & Pharmacology, Nutrition Keywords: cholesterol synthesis; bile acid synthesis; cholesterol absorption; lathosterol; plant sterols; oxysterols; lipoproteins; lipid lowering; phytosterols; placebo
Online: 10 January 2018 (10:51:03 CET)
Chitosan treatment results in significantly lower serum LDL cholesterol concentrations. To assess the working mechanism of chitosan, we measured serum surrogate markers of cholesterol absorption (campesterol, sitosterol, cholestanol), synthesis (lathosterol, lanosterol, desmosterol), and degradation to bile acids (7α-hydroxy-cholesterol, 27-hydroxy-cholesterol) corrected for cholesterol concentration (R_sterols). Over 12 weeks, 116 obese subjects (BMI 31.7, range 28.1 – 38.9 kg/m2) were studied under chitosan (n=61) and placebo treatment (n=55). The participants were briefly educated regarding improvement of nutrition quality and energy expenditure. Daily chitosan intake was 3200 mg. Serum LDL cholesterol concentration decreased significantly more (P=0.0252) under chitosan (-8.67 ± 18.18 mg/dl, 5.6%) than under placebo treatment (-1.00 ± 24.22 mg/dl, 0.9%). This reduction was not associated with the expected greater decreases in markers of cholesterol absorption under chitosan treatment. Also, increase in markers of cholesterol synthesis and bile acid synthesis under chitosan treatment was not any greater than under placebo treatment. In conclusion, a significant selective reduction of serum LDL cholesterol under chitosan treatment is neither associated with a reduction of serum surrogate markers of cholesterol absorption nor with an increases of markers for cholesterol and bile acid synthesis.