Highly efficient synergistic activity of an α-L-arabinofuranosidase for degradation of arabinoxylan in barley/wheat.

Here, an α-L-arabinofuranosidase (termed TtAbf62) from Thermothelomyces thermophilus is described, which efficiently removes arabinofuranosyl side chains and facilitates arabinoxylan digestion. The specific activity of TtAbf62 (179.07 U/mg) toward wheat arabinoxylan was the highest among all characterized glycoside hydrolase family 62 enzymes. TtAbf62 in combination with endoxylanase and ß-xylosidase strongly promoted hydrolysis of barley and wheat. The release of reducing sugars was significantly higher for the three-enzyme combination relative to the sum of single-enzyme treatments: 85.71% for barley hydrolysis and 33.33% for wheat hydrolysis. HPLC analysis showed that TtAbf62 acted selectively on monosubstituted (C-2 or C-3) xylopyranosyl residues rather than double-substituted residues. Site-directed mutagenesis and interactional analyses of enzyme-substrate binding structures revealed the catalytic sites of TtAbf62 formed different polysaccharide-catalytic binding modes with arabinoxylo-oligosaccharides. Our findings demonstrate a "multienzyme cocktail" formed by TtAbf62 with other hydrolases strongly improves the efficiency of hemicellulose conversion and increases biomass hydrolysis through synergistic interaction.

Neutralizing serum amyloid a protects against sinusoidal endothelial cell damage and platelet aggregation during acetaminophen-induced liver injury.

Serum amyloid A (SAA) is an acute response protein that mainly produced by hepatocytes, and it can promote endothelial dysfunction via a pro-inflammatory and pro-thrombotic effect in atherosclerosis and renal disease. Overdose of Acetaminophen (APAP) will cause hepatotoxicity accompany with hepatocyte necrosis, liver sinusoidal endothelial cells (LSECs) damage and thrombosis in liver. However, whether SAA plays a role in APAP-induced liver toxicity remains unclear. Here, we evaluated the Saa1/2 expression in APAP-induced liver injury, and found that Saa1/2 production was significantly increased in an autocrine manner in APAP injury model. Moreover, we used neutralizing antibody (anti-SAA) to block the function of serum Saa1/2. We found that neutralizing serum Saa1/2 protected against APAP-induced liver injuries and increased the survival rate of mice that were treated with lethal dose APAP. Further investigations showed that blocking Saa1/2 reduced APAP-induced sinusoidal endothelium damage, hemorrhage and thrombosis. In addition, in vitro experiments showed that Saa1/2 augmented the toxic effect of APAP on LSECs, and Saa1/2 promoted platelets aggregation on LSECs cell membrane. Taken together, this study suggests that Saa1/2 may play a critical role in APAP-induced liver damages through platelets aggregation and sinusoidal damage. Therefore, we conceptually demonstrate that inhibition of SAA may be a potential intervention for APAP-directed acute liver injuries.

SAA1/TLR2 axis directs chemotactic migration of hepatic stellate cells responding to injury.

Hepatic stellate cells (HSCs) are crucial for liver injury repair and cirrhosis. However, the mechanism of chemotactic recruitment of HSCs into injury loci is still largely unknown. Here, we demonstrate that serum amyloid A1 (SAA1) acts as a chemokine recruiting HSCs toward injury loci signaling via TLR2, a finding proven by gene manipulation studies in cell and mice models. The mechanistic investigations revealed that SAA1/TLR2 axis stimulates the Rac GTPases through PI3K-dependent pathways and induces phosphorylation of MLC (pSer19). Genetic deletion of TLR2 and pharmacological inhibition of PI3K diminished the phosphorylation of MLCpSer19 and migration of HSCs. In brief, SAA1 serves as a hepatic endogenous chemokine for the TLR2 receptor on HSCs, thereby initiating PI3K-dependent signaling and its effector, Rac GTPases, which consequently regulates actin filament remodeling and cell directional migration. Our findings provide novel targets for anti-fibrosis drug development.

Generation of WAe001-A-58 human embryonic stem cell line with inducible expression of the SARS-CoV-2 nucleocapsid protein.

Excessive prostaglandin E2 (PGE2) is the key pathological basis for COVID-19 and a Celebrex treatment of hospitalized COVID-19 patients with comorbidities led to 100% discharged rate and zero death (Hong et al. 2020). It is also suggested that SARS-CoV-2 infected multiple organs and the SARS-CoV nucleocapsid (N) protein transcriptionally drives the expression of the host COX-2 gene. In order to test whether SARS-CoV-2 N protein activates COX-2 transcription in multiple human relevant cell types, an expression inducible human embryonic stem cell line was generated by piggyBac transposon system. This cell line maintained its pluripotency, differentiation potentials, normal morphology and karyotype.

Robust expansion and functional maturation of human hepatoblasts by chemical strategy.

BACKGROUND: Chemically strategies to generate hepatic cells from human pluripotent stem cells (hPSCs) for the potential clinical application have been improved. However, producing high quality and large quantities of hepatic cells remain challenging, especially in terms of step-wise efficacy and cost-effective production requires more improvements. METHODS: Here, we systematically evaluated chemical compounds for hepatoblast (HB) expansion and maturation to establish a robust, cost-effective, and reproducible methodology for self-renewal HBs and functional hepatocyte-like cell (HLC) production. RESULTS: The established chemical cocktail could enable HBs to proliferate nearly 3000 folds within 3 weeks with preserved bipotency. Moreover, those expanded HBs could be further efficiently differentiated into homogenous HLCs which displayed typical morphologic features and functionality as mature hepatocytes including hepatocyte identity marker expression and key functional activities such as cytochrome P450 metabolism activities and urea secretion. Importantly, the transplanted HBs in the injured liver of immune-defect mice differentiated as hepatocytes, engraft, and repopulate in the injured loci of the recipient liver. CONCLUSION: Together, this chemical compound-based HLC generation method presents an efficient and cost-effective platform for the large-scale production of functional human hepatic cells for cell-based therapy and drug discovery application.

Icaritin ameliorates hepatic steatosis via promoting fatty acid ß-oxidation and insulin sensitivity.

AIM: This study aimed to reveal the effects of icaritin (ICT) on lipotoxicity induced by palmitate (PA) in hepatic cells and steatosis in high-fat diet (HFD)-fed mice as well as exploring the potential mechanisms. MAIN METHODS: Primary mouse hepatocytes and human hepatoma Huh7 cells were used to evaluate ICT effect in vitro. HFD-fed mice were used to evaluate the ICT effect in vivo. RESULTS: In vitro study indicated that ICT significantly rescued PA-induced steatosis, mainly through a combination of robust increased mitochondrial respiration, fatty acid oxidation and mildly decreased synthesis of fatty acid. An HFD-fed mouse model with 8 weeks HFD-fed showed metabolic disorders, while ICT application significantly reduced the weight, serum glucose levels, insulin resistance, hepatic steatosis level and adipose contents. In consistent with the observations in cell lines, ICT rescued the HFD-impaired functions and contents of key factors related to fatty acid ß-oxidation through elevated expression of peroxisome proliferator-activated receptor α (PPARα). Meanwhile, it also reversed the decreased phosphoryl levels of AKT and glucogen synthase kinase 3 (GSK3ß), leading to the improvement of insulin resistance. SIGNIFICANCE: ICT administration had a therapeutic effect on PA- or HFD-induced hepatic steatosis and metabolic disorders. It may provide a novel strategy to construct preventive and therapeutic means for hepatic steatosis.

Celebrex Adjuvant Therapy on Coronavirus Disease 2019: An Experimental Study.

Background: The pandemic of coronavirus disease 2019 (COVID-19) resulted in grave morbidity and mortality worldwide. There is currently no effective drug to cure COVID-19. Based on analyses of available data, we deduced that excessive prostaglandin E2 (PGE2) produced by cyclooxygenase-2 was a key pathological event of COVID-19. Methods: A prospective clinical study was conducted in one hospital for COVID-19 treatment with Celebrex to suppress the excessive PGE2 production. A total of 44 COVID-19 cases were enrolled, 37 cases in the experimental group received Celebrex as adjuvant (full dose: 0.2 g, bid; half dose: 0.2 g, qd) for 7-14 days, and the dosage and duration was adjusted for individuals, while seven cases in the control group received the standard therapy. The clinical outcomes were evaluated by measuring the urine PGE2 levels, lab tests, CT scans, vital signs, and other clinical data. The urine PGE2 levels were measured by mass spectrometry. The study was registered and can be accessed at http://www.chictr.org.cn/showproj.aspx?proj=50474. Results: The concentrations of PGE2 in urine samples of COVID-19 patients were significantly higher than those of PGE2 in urine samples of healthy individuals (mean value: 170 ng/ml vs 18.8 ng/ml, p < 0.01) and positively correlated with the progression of COVID-19. Among those 37 experimental cases, there were 10 cases with age over 60 years (27%, 10/37) and 13 cases (35%, 13/37) with preexisting conditions including cancer, atherosclerosis, and diabetes. Twenty-five cases had full dose, 11 cases with half dose of Celebrex, and one case with ibuprofen. The remission rates in midterm were 100%, 82%, and 57% of the full dose, half dose, and control group, respectively, and the discharged rate was 100% at the endpoint with Celebrex treatment. Celebrex significantly reduced the PGE2 levels and promoted recovery of ordinary and severe COVID-19. Furthermore, more complications, severity, and death rate were widely observed and reported in the COVID-19 group of elders and with comorbidities; however, this phenomenon did not appear in this particular Celebrex adjunctive treatment study. Conclusion: This clinical study indicates that Celebrex adjuvant treatment promotes the recovery of all types of COVID-19 and further reduces the mortality rate of elderly and those with comorbidities.

Ascorbate protects liver from metabolic disorder through inhibition of lipogenesis and suppressor of cytokine signaling 3 (SOCS3).

BACKGROUND: Fatty liver is a reversible status, but also an origin stage to develop to other metabolic syndromes, such as diabetes and heart disease that threatens public health worldwide. Ascorbate deficiency is reported to be correlated with increasing risks for metabolic syndromes, but whether ascorbate has a therapeutic effect is unknown. Here, we investigated if ascorbate treatment alone could work on protecting from the development of steatosis and mechanisms beyond. METHODS: Guinea pigs were fed with a chow diet or a high palm oil diet (HPD) respectively. HPD induced animals were administered different concentrations of ascorbate in different time intervals through water. Besides, hepatocyte-like cells derived from human embryonic stem cells and HepG2 cells were treated with palmitic acid (PA) to induce lipid accumulation for molecular mechanism study. RESULTS: We find that ascorbate rescues HPD and PA induced steatosis and insulin tolerance in vivo and in vitro. We demonstrate that ascorbate changes cellular lipid profiles via inhibits lipogenesis, and inhibits the expression of SOCS3 via STAT3, thus enhances insulin signal transduction. Overexpression of SOCS3 abolishes the ascorbate rescue effects on insulin signal and lipid accumulation in hepatic cells. CONCLUSIONS: Ascorbate ameliorates hepatic steatosis and improves insulin sensitivity through inhibiting lipogenesis and SOCS3.

Generation of a SMO homozygous knockout human embryonic stem cell line WAe001-A-16 by CRISPR/Cas9 editing.

The human SMO protein encoded by the smoothened (SMO) gene acts as a positive mediator for Hedgehog signaling. This pathway regulates many cellular activities, developmental morphogenesis, and tumorigenesis. Using CRISPR/Cas9 to edit human embryonic stem cell line WA01 (H1), we established a SMO mutant cell line (WAe001-A-16). This cell line has a 40bp homozygous deletion in exon 2 of SMO leading to a shift in the open reading frame and early termination at amino acid position 287. WAe001-A-16 maintains a normal karyotype, parental cell morphology, pluripotency markers, and the capacity to differentiate into all three germline layers.