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Cell Stem Cell Jul 2018Chronic liver injury can cause cirrhosis and impaired liver regeneration, impairing organ function. Adult livers can regenerate in response to parenchymal insults, and...
Chronic liver injury can cause cirrhosis and impaired liver regeneration, impairing organ function. Adult livers can regenerate in response to parenchymal insults, and multiple cellular sources have been reported to contribute to this response. In this study, we modeled human chronic liver injuries, in which such responses are blunted, without genetic manipulations, and assessed potential contributions of non-parenchymal cells (NPCs) to hepatocyte regeneration. We show that NPC-derived hepatocytes replenish a large fraction of the liver parenchyma following severe injuries induced by long-term thioacetamide (TAA) or 3,5-diethoxycarbonyl-1,4-dihydrocollidine (DDC) treatment. Through lineage tracing of biliary epithelial cells (BECs), we show that BECs are a source of new hepatocytes and gain an Hnf4αCK19 bi-phenotypic state in periportal regions and fibrotic septa. Bi-phenotypic cells were also detected in cirrhotic human livers. Together, these data provide further support for hepatocyte regeneration from BECs without genetic interventions and show their cellular plasticity during severe liver injury.
Topics: Animals; Chronic Disease; Epithelial Cells; Hepatocytes; Humans; Liver Cirrhosis; Mice; Mice, Inbred Strains; Thioacetamide
PubMed: 29937200
DOI: 10.1016/j.stem.2018.05.022 -
Cell Stem Cell Jul 2018The development of complex in vitro hepatic systems and artificial liver devices has been hampered by the lack of reliable sources for relevant cell types, such as...
The development of complex in vitro hepatic systems and artificial liver devices has been hampered by the lack of reliable sources for relevant cell types, such as hepatic stellate cells (HSCs). Here we report efficient differentiation of human pluripotent stem cells into HSC-like cells (iPSC-HSCs). iPSC-HSCs closely resemble primary human HSCs at the transcriptional, cellular, and functional levels and possess a gene expression profile intermediate between that of quiescent and activated HSCs. Functional analyses revealed that iPSC-HSCs accumulate retinyl esters in lipid droplets and are activated in response to mediators of wound healing, similar to their in vivo counterparts. When maintained as 3D spheroids with HepaRG hepatocytes, iPSC-HSCs exhibit a quiescent phenotype but mount a fibrogenic response and secrete pro-collagen in response to known stimuli and hepatocyte toxicity. Thus, this protocol provides a robust in vitro system for studying HSC development, modeling liver fibrosis, and drug toxicity screening.
Topics: Cell Differentiation; Cells, Cultured; Coculture Techniques; Female; Hepatic Stellate Cells; Humans; Infant, Newborn; Liver Cirrhosis; Male; Models, Biological; Pluripotent Stem Cells; Thioacetamide; Wound Healing
PubMed: 30049452
DOI: 10.1016/j.stem.2018.05.027 -
Beilstein Journal of Organic Chemistry 2021After completing the thio-substitution with Lawesson's reagent, ethanol was found to be effective in the decomposition of the inherent stoichiometric six-membered-ring...
After completing the thio-substitution with Lawesson's reagent, ethanol was found to be effective in the decomposition of the inherent stoichiometric six-membered-ring byproduct from the Lawesson's reagent to a highly polarized diethyl thiophosphonate. The treatment significantly simplified the following chromatography purification of the desired thioamide in a small scale preparation. As scaling up the preparation of two pincer-type thioamides, we have successfully developed a convenient process with ethylene glycol to replace ethanol during the workup, including a traditional phase separation, extraction, and recrystallization. The newly developed chromatography-free procedure did not generate P-containing aqueous waste, and only organic effluents were discharged. It is believed that the optimized procedure offers the great opportunity of applying the Lawesson's reagent for various thio-substitution reactions on a large scale.
PubMed: 33889221
DOI: 10.3762/bjoc.17.69 -
Free Radical Biology & Medicine Jan 2021Liver fibrosis is a reversible wound-healing response to acute or chronic liver injury that can progress to cirrhosis and liver cancer. Finding new strategies for...
Liver fibrosis is a reversible wound-healing response to acute or chronic liver injury that can progress to cirrhosis and liver cancer. Finding new strategies for prevention and management of liver fibrosis is urgently needed. It is known that hepatic stellate cell (HSC) is the primary source of extracellular matrix that drives liver fibrosis progression. Herein, we carried out a comprehensive secretome profiling to identify NMN-induced changes in secretory proteins and found that NMN suppressed the secretion of profibrotic protein and oxidoreductase in activated HSC (LX-2) cells, while real-time quantitative PCR analysis revealed that NMN downregulated profibrotic gene expression, resulting in HSC inactivation. Next, we demonstrated that nicotinamide mononucleotide (NMN) reduced the accumulation of liver extracellular matrix in thioacetamide (TAA) and carbon tetrachloride (CCl) induced mouse models for liver fibrosis. Furthermore, we determined that NMN inhibited oxidation-mediated 15-PGDH degradation to promote prostaglandin E degradation and suppress HSC activation. In summary, our results propose that NMN supplementation is a new therapeutic approach for liver fibrosis prevention.
Topics: Animals; Dinoprostone; Hepatic Stellate Cells; Liver; Liver Cirrhosis; Mice; Nicotinamide Mononucleotide; Thioacetamide
PubMed: 33220424
DOI: 10.1016/j.freeradbiomed.2020.11.014 -
Nature Communications Jul 2023Oxidative stress plays a crucial role in the pathogenesis of hepatic encephalopathy (HE), but the mechanism remains unclear. GABAergic neurons in substantia nigra pars...
Oxidative stress plays a crucial role in the pathogenesis of hepatic encephalopathy (HE), but the mechanism remains unclear. GABAergic neurons in substantia nigra pars reticulata (SNr) contribute to the motor deficit of HE. The present study aims to investigate the effects of oxidative stress on HE in male mice. The results validate the existence of oxidative stress in both liver and SNr across two murine models of HE induced by thioacetamide (TAA) and bile duct ligation (BDL). Systemic mitochondria-targeted antioxidative drug mitoquinone (Mito-Q) rescues mitochondrial dysfunction and oxidative injury in SNr, so as to restore the locomotor impairment in TAA and BDL mice. Furthermore, the GAD2-expressing SNr population (SNr) is activated by HE. Both overexpression of mitochondrial uncoupling protein 2 (UCP2) targeted to SNr and SNr-targeted chemogenetic inhibition targeted to SNr rescue mitochondrial dysfunction in TAA-induced HE. These results define the key role of oxidative stress in the pathogenesis of HE.
Topics: Male; Animals; Mice; Hepatic Encephalopathy; Oxidative Stress; Antioxidants; Bile Ducts; Thioacetamide
PubMed: 37488119
DOI: 10.1038/s41467-023-40081-8 -
Nature Communications May 2020Due to their bacterial ancestry, many components of mitochondria share structural similarities with bacteria. Release of molecular danger signals from injured cell...
Due to their bacterial ancestry, many components of mitochondria share structural similarities with bacteria. Release of molecular danger signals from injured cell mitochondria (mitochondria-derived damage-associated molecular patterns, mito-DAMPs) triggers a potent inflammatory response, but their role in fibrosis is unknown. Using liver fibrosis resistant/susceptible mouse strain system, we demonstrate that mito-DAMPs released from injured hepatocyte mitochondria (with mtDNA as major active component) directly activate hepatic stellate cells, the fibrogenic cell in the liver, and drive liver scarring. The release of mito-DAMPs is controlled by efferocytosis of dying hepatocytes by phagocytic resident liver macrophages and infiltrating Gr-1(+) myeloid cells. Circulating mito-DAMPs are markedly increased in human patients with non-alcoholic steatohepatitis (NASH) and significant liver fibrosis. Our study identifies specific pathway driving liver fibrosis, with important diagnostic and therapeutic implications. Targeting mito-DAMP release from hepatocytes and/or modulating the phagocytic function of macrophages represents a promising antifibrotic strategy.
Topics: Adult; Aged; Aged, 80 and over; Alarmins; Animals; Apoptosis; Disease Models, Animal; Disease Progression; Female; Hepatic Stellate Cells; Hepatocytes; Humans; Liver; Liver Cirrhosis; Macrophages; Male; Mice; Middle Aged; Mitochondria; Non-alcoholic Fatty Liver Disease; Phagocytosis; Thioacetamide; Young Adult
PubMed: 32398673
DOI: 10.1038/s41467-020-16092-0 -
ACS Chemical Biology Feb 2019Thioamidation as a posttranslational modification is exceptionally rare, with only a few reported natural products and exactly one known protein example (methyl-coenzyme... (Review)
Review
Thioamidation as a posttranslational modification is exceptionally rare, with only a few reported natural products and exactly one known protein example (methyl-coenzyme M reductase from methane-metabolizing archaea). Recently, there has been significant progress in elucidating the biosynthesis and function of several thioamide-containing natural compounds. Separate developments in the chemical installation of thioamides into peptides and proteins have enabled cell biology and biophysical studies to advance the current understanding of natural thioamides. This review highlights the various strategies used by Nature to install thioamides in peptidic scaffolds and the potential functions of this rare but important modification. We also discuss synthetic methods used for the site-selective incorporation of thioamides into polypeptides with a brief discussion of the physicochemical implications. This account will serve as a foundation for the further study of thioamides in natural products and their various applications.
Topics: Biological Products; Molecular Structure; Thioamides
PubMed: 30698414
DOI: 10.1021/acschembio.8b01022 -
Critical Reviews in Biochemistry and... 2022Sulfur is an essential element for a variety of cellular constituents in all living organisms and adds considerable functionality to a wide range of biomolecules. The... (Review)
Review
Sulfur is an essential element for a variety of cellular constituents in all living organisms and adds considerable functionality to a wide range of biomolecules. The pathways for incorporating sulfur into central metabolites of the cell such as cysteine, methionine, cystathionine, and homocysteine have long been established. Furthermore, the importance of persulfide intermediates during the biosynthesis of thionucleotide-containing tRNAs, iron-sulfur clusters, thiamin diphosphate, and the molybdenum cofactor are well known. This review briefly surveys these topics while emphasizing more recent aspects of sulfur metabolism that involve unconventional biosynthetic pathways. Sacrificial sulfur transfers from protein cysteinyl side chains to precursors of thiamin and the nickel-pincer nucleotide (NPN) cofactor are described. Newer aspects of synthesis for lipoic acid, biotin, and other compounds are summarized, focusing on the requisite iron-sulfur cluster destruction. Sulfur transfers by using a noncore sulfide ligand bound to a [4Fe-4S] cluster are highlighted for generating certain thioamides and for alternative biosynthetic pathways of thionucleotides and the NPN cofactor. Thioamide formation by activating an amide oxygen atom via phosphorylation also is illustrated. The discussion of these topics stresses the chemical reaction mechanisms of the transformations and generally avoids comments on the gene/protein nomenclature or the sources of the enzymes. This work sets the stage for future efforts to decipher the diverse mechanisms of sulfur incorporation into biological molecules.
Topics: Sulfur; Coenzymes; Thiamine; Iron
PubMed: 36403141
DOI: 10.1080/10409238.2022.2141678 -
Endokrynologia Polska 2015Amiodarone, a benzofuranic iodine-rich antiarrhythmic drug, causes thyroid dysfunction in 15-20% of cases. Amiodarone can cause both hypothyroidism (AIH,... (Review)
Review
Amiodarone, a benzofuranic iodine-rich antiarrhythmic drug, causes thyroid dysfunction in 15-20% of cases. Amiodarone can cause both hypothyroidism (AIH, amiodarone-induced hypothyroidism) and thyrotoxicosis (AIT, amiodarone-induced thyrotoxicosis). AIH is treated by L-thyroxin replacement and does not need amiodarone discontinuation. There are two main forms of AIT: type 1, a form of true iodine-induced hyperthyroidism; and type 2, a drug-induced destructive thyroiditis. However, mixed/indefinite forms exist, contributed to by both pathogenic mechanisms. Type 1 AIT usually occurs in diseased thyroid glands, whereas type 2 AIT develops in substantially normal thyroid glands. Thioamides represent the first-line treatment for type 1 AIT, but iodine-replete glands are poorly responsive; sodium/potassium perchlorate, by inhibiting thyroidal iodine uptake, may increase the response to thioamides. Type 2 AIT is best treated by oral glucocorticoids. Response depends on thyroid volume and severity of thyrotoxicosis. Mixed/indefinite forms may require a combination of thioamides, potassium perchlorate, and steroids. Radioiodine treatment is usually not feasible because amiodarone-related iodine load decreases thyroidal radioiodine uptake. Thyroidectomy represents an important and helpful option in cases resistant to medical therapy. Surgery performed by a skilled surgeon may represent an emergent treatment in patients who have severe cardiac dysfunction.
Topics: Aged; Amiodarone; Anti-Arrhythmia Agents; Female; Glucocorticoids; Humans; Hypothyroidism; Male; Middle Aged; Thioamides; Thyroid Gland; Thyrotoxicosis; Thyroxine
PubMed: 25931048
DOI: 10.5603/EP.2015.0025 -
Current Opinion in HIV and AIDS Nov 2012Individuals practicing unprotected receptive anal intercourse are at particularly high risk of HIV infection. Men who have sex with men (MSM) in the developed and... (Review)
Review
PURPOSE OF REVIEW
Individuals practicing unprotected receptive anal intercourse are at particularly high risk of HIV infection. Men who have sex with men (MSM) in the developed and developing world continue to have disproportionate and increasing levels of HIV infection. The past few years have seen important progress in demonstrating the efficacy of oral pre-exposure prophylaxis (PrEP), vaginal microbicides, and treatment as prevention, but there has also been significant progress in the development of rectal microbicides. The purpose of this review is to summarize the status of rectal microbicide research and to identify opportunities, challenges, and future directions in this important field of HIV prevention.
RECENT FINDINGS
Recent phase 1 rectal microbicide studies have characterized the safety, acceptability, compartmental pharmacokinetics, and pharmacodynamics of both UC781 and tenofovir gels. The tenofovir gel formulation used in vaginal studies was not well tolerated in the rectum and newer rectal-specific formulations have been developed and evaluated in phase 1 studies.
SUMMARY
Complex phase 1 studies have provided important data on candidate rectal microbicides. Tenofovir gel is poised to move into phase 2 evaluation and it is possible that a phase 2B/3 effectiveness study could be initiated in the next 2-3 years.
Topics: Adenine; Administration, Rectal; Administration, Topical; Anilides; Anti-HIV Agents; Chemoprevention; Clinical Trials, Phase I as Topic; Drug-Related Side Effects and Adverse Reactions; Furans; HIV Infections; Homosexuality, Male; Humans; Male; Organophosphonates; Tenofovir; Thioamides
PubMed: 23032732
DOI: 10.1097/COH.0b013e3283582bc2