Prevotella copri promotes vascular calcification via lipopolysaccharide through activation of NF-κB signaling pathway.

Emerging evidence indicates that alteration of gut microbiota plays an important role in chronic kidney disease (CKD)-related vascular calcification (VC). We aimed to investigate the specific gut microbiota and the underlying mechanism involved in CKD-VC. We identified an increased abundance of Prevotella copri (P. copri) in the feces of CKD rats (induced by using 5/6 nephrectomy followed by a high calcium and phosphate diet) with aortic calcification via amplicon sequencing of 16S rRNA genes. In patients with CKD, we further confirmed a positive correlation between abundance of P. copri and aortic calcification scores. Moreover, oral administration of live P. copri aggravated CKD-related VC and osteogenic differentiation of vascular smooth muscle cells in vivo, accompanied by intestinal destruction, enhanced expression of Toll-like receptor-4 (TLR4), and elevated lipopolysaccharide (LPS) levels. In vitro and ex vivo experiments consistently demonstrated that P. copri-derived LPS (Pc-LPS) accelerated high phosphate-induced VC and VSMC osteogenic differentiation. Mechanistically, Pc-LPS bound to TLR4, then activated the nuclear factor κB (NF-κB) and nucleotide-binding domain, leucine-rich-containing family, pyrin domain-containing-3 (NLRP3) inflammasome signals during VC. Inhibition of NF-κB reduced NLRP3 inflammasome and attenuated Pc-LPS-induced VSMC calcification. Our study clarifies a novel role of P. copri in CKD-related VC, by the mechanisms involving increased inflammation-regulating metabolites including Pc-LPS, and activation of the NF-κB/NLRP3 signaling pathway. These findings highlight P. copri and its-derived LPS as potential therapeutic targets for VC in CKD.

Remnant cholesterol and the risk of aortic valve calcium progression: insights from the MESA study.

BACKGROUND: Remnant cholesterol (RC) is implicated in the risk of cardiovascular disease. However, comprehensive population-based studies elucidating its association with aortic valve calcium (AVC) progression are limited, rendering its precise role in AVC ambiguous. METHODS: From the Multi-Ethnic Study of Atherosclerosis database, we included 5597 individuals (61.8 ± 10.1 years and 47.5% men) without atherosclerotic cardiovascular disease at baseline for analysis. RC was calculated as total cholesterol minus high-density lipoprotein cholesterol (HDL-C) and low-density lipoprotein cholesterol (LDL-C), as estimated by the Martin/Hopkins equation. Using the adjusted Cox regression analyses, we examined the relationships between RC levels and AVC progression. Furthermore, we conducted discordance analyses to evaluate the relative AVC risk in RC versus LDL-C discordant/concordant groups. RESULTS: During a median follow-up of 2.4 ± 0.9 years, 568 (10.1%) participants exhibited AVC progression. After adjusting for traditional cardiovascular risk factors, the HRs (95% CIs) for AVC progression comparing the second, third, and fourth quartiles of RC levels with the first quartile were 1.195 (0.925-1.545), 1.322 (1.028-1.701) and 1.546 (1.188-2.012), respectively. Notably, the discordant high RC/low LDL-C group demonstrated a significantly elevated risk of AVC progression compared to the concordant low RC/LDL-C group based on their medians (HR, 1.528 [95% CI 1.201-1.943]). This pattern persisted when clinical LDL-C threshold was set at 100 and 130 mg/dL. The association was consistently observed across various sensitivity analyses. CONCLUSIONS: In atherosclerotic cardiovascular disease-free individuals, elevated RC is identified as a residual risk for AVC progression, independent of traditional cardiovascular risk factors. The causal relationship of RC to AVC and the potential for targeted RC reduction in primary prevention require deeper exploration.

STAT4-Mediated Klotho Up-Regulation Contributes to the Brain Ischemic Tolerance by Cerebral Ischemic Preconditioning via Inhibiting Neuronal Pyroptosis.

Our previous study has proved that the Klotho up-regulation participated in cerebral ischemic preconditioning (CIP)-induced brain ischemic tolerance. However, the exact neuroprotective mechanism of Klotho in CIP remains unclear. We explored the hypothesis that STAT4-mediated Klotho up-regulation contributes to the CIP-induced brain ischemic tolerance via inhibiting neuronal pyroptosis. Firstly, the expressions of pyroptosis-associated proteins (i.e., NLRP3, GSDMD, pro-caspase-1, and cleaved caspase-1) in hippocampal CA1 region were determined during the process of brain ischemic tolerance. We found the expression of pyroptosis-associated proteins was significantly up-regulated in the ischemic insult (II) group, and showed no significant changes in the CIP group. The expression level of each pyroptosis-associated proteins was lower in the CIP + II group than that in the II group. Inhibition of Klotho expression increased the expression of pyroptosis-associated proteins in the CIP + II group and blocked the CIP-induced brain ischemic tolerance. Injection of Klotho protein decreased the expression of pyroptosis-associated proteins in the II group, and protected neurons from ischemic injury. Secondly, the transcription factor STAT4 of Klotho was identified by bioinformatic analysis. Double luciferase reporter gene assay and chromatin immunoprecipitation assay showed STAT4 can bind to the site between nt - 881 and - 868 on the Klotho promoter region and positively regulates Klotho expression. Moreover, we found CIP significantly enhanced the expression of STAT4. Knockdown STAT4 suppressed Klotho up-regulation after CIP and blocked the CIP-induced brain ischemic tolerance. Collectively, it can be concluded that STAT4-mediated the up-regulation of Klotho contributed to the brain ischemic tolerance induced by CIP via inhibiting pyroptosis.

The Role of Astrocytic Mitochondria in the Pathogenesis of Brain Ischemia.

The morbidity rate of ischemic stroke is increasing annually with the growing aging population in China. Astrocytes are ubiquitous glial cells in the brain and play a crucial role in supporting neuronal function and metabolism. Increasing evidence shows that the impairment or loss of astrocytes contributes to neuronal dysfunction during cerebral ischemic injury. The mitochondrion is increasingly recognized as a key player in regulating astrocyte function. Changes in astrocytic mitochondrial function appear to be closely linked to the homeostasis imbalance defects in glutamate metabolism, Ca2+ regulation, fatty acid metabolism, reactive oxygen species, inflammation, and copper regulation. Here, we discuss the role of astrocytic mitochondria in the pathogenesis of brain ischemic injury and their potential as a therapeutic target.

A Novel Cuproptosis-Related Signature Identified DLAT as a Prognostic Biomarker for Hepatocellular Carcinoma Patients.

Background: Hepatocellular carcinoma (HCC) is the most common type of liver cancers, with more than a million cases per year by 2025. Cuproptosis is a novel form of programmed cell death, and is caused by mitochondrial lipoylation and destabilization of iron-sulfur proteins triggered by copper, which was considered as a key player in various biological processes. However, the roles of cuproptosis-related genes (CRGs) in HCC remain largely unknown. Methods: In the present study, we constructed and validated a four CRGs signature for predicting the overall survival (OS) of HCC patients in both The Cancer Genome Atlas (TCGA) and International Cancer Genome Consortium (ICGC) databases. Results: Patients with high CRGs risk score showed shorter OS than those with low CRGs risk score. Functional analysis suggested that the CRGs-based prognostic signature was associated with metabolism remodeling which facilitated liver cancer progression. In addition, reduced infiltration of CD8+ T cells and increased macrophages were found in HCCs from patients with high CRGs risk score. As one of the four CRGs, higher expression of dihydrolipoamide S-acetyltransferase (DLAT) was accompanied by higher expression of program death ligand 1 (PD-L1) in HCC. Further, we confirmed that DLAT was up-regulated and correlated with poor prognosis in a clinical HCC cohort. Conclusion: In conclusion, our study constructed a four CRGs signature prognostic model and identified DLAT as an independent prognostic factor for HCC, thus providing new clues for understanding the association between cuproptosis and HCC.

The Regulation of Autophagy by p38 MAPK-PPARγ Signaling During the Brain Ischemic Tolerance Induced by Cerebral Ischemic Preconditioning.

Several studies indicated that autophagy activation participates in brain ischemic tolerance (BIT) induced by cerebral ischemic preconditioning (CIP). However, the mechanism of autophagy activation during the process still remains unclear. The present study aimed to evaluate the role of p38 MAPK-peroxisome proliferator-activated receptor γ (PPARγ) signaling cascade in autophagy during the CIP-induced BIT. The results shown that, initially, autophagy activation was observed after CIP in the model of global cerebral ischemia in rats, as was indicated by the upregulation of Beclin 1 expression, an increase in LC3-II/LC3-I ratio, the enhanced LC3 immunofluorescence, and a rise in the number of autophagosomes in the neurons of the hippocampal CA1 area. Besides, the inhibitor of autophagy 3-methyladenine obliterated the neuroprotection induced by CIP. Furthermore, the upregulation of p-p38 MAPK and PPARγ expressions was earlier than autophagy activation after CIP. In addition, pretreatment with SB203580 (the inhibitor of p38 MAPK) reversed CIP-induced PPARγ upregulation, autophagy activation, and neuroprotection. Pretreatment with GW9662 (the inhibitor of PPARγ) reversed autophagy activation and neuroprotection, while it had no effect on p-p38 MAPK upregulation induced by CIP. These data suggested that the p38 MAPK-PPARγ signaling pathway participates in autophagy activation during the induction of BIT by CIP.

Na+-K+-2Cl- cotransporter 2 located in the human and murine gastric mucosa is involved in secretagogue-induced gastric acid secretion and is downregulated in lipopolysaccharide-treated mice.

Na+-K+-2Cl- cotransporter (NKCC) is expressed at exceptionally high levels in gastric parietal cells. Bumetanide, a potent loop diuretic that blocks NKCC, usually causes a decrease in gastric acid secretion. Endotoxaemia causes hypochlorhydria in vivo, in which lipopolysaccharide (LPS) plays an important role. This study aimed to investigate the effect of NKCC2 on gastric acid secretion and its alteration in LPS-treated mice. The scanning ion-selective electrode technique and real-time pH titration combined with RNA interference were used to determine the effects of bumetanide on gastric acid secretion. Immunochemistry and Western blotting were performed to investigate the changes in NKCC2 expression in LPS-treated mice. Immunoreactivity of NKCC1 and NKCC2 was mainly observed near the basolateral and apical membranes of parietal cells, respectively. Pretreatment with bumetanide reduced the histamine-stimulated H+ flux in the mouse gastric mucosa. The apical, but not the basolateral, addition of bumetanide inhibited forskolin- or histamine/3-isobutyl-1-methylxanthine(IBMX)-induced gastric acid secretion. In vivo treatment with NKCC2 siRNA inhibited forskolin-induced acid secretion. Upon histamine stimulation, the majority of NKCC2 was targeted to the apical membrane in the gastric mucosa and in primary cultured parietal cells. The expression of NKCC2 and vesicle-associated membrane protein-2 (VAMP2), but not that of H+/K+-ATPase, was decreased in the gastric mucosa of LPS-treated mice. Blocking apical NKCC2, but not basolateral NKCC1, by bumetanide inhibited secretagogue-induced gastric acid secretion, during which the membrane trafficking of NKCC2 may be necessary. The downregulation of NKCC2 and VAMP2 may be related to the reduced gastric acid secretion induced by LPS.

High FLT3 Levels May Predict Sorafenib Benefit in Hepatocellular Carcinoma.

PURPOSE: To identify a predictive biomarker of sorafenib for hepatocellular carcinoma personalized therapy. EXPERIMENTAL DESIGN: The patients treated with or without sorafenib after hepatocellular carcinoma recurrence from multicenters were matched with propensity score matching analysis. The expression levels of Fms-like tyrosine kinase 3 (FLT3) in hepatocellular carcinoma specimens of the matched patients (n = 276) were analyzed by IHC. The optimal cut-off point of FLT3 levels for overall survival (OS) was defined via Cutoff Finder. Subgroup analysis of OS was employed to investigate the association between FLT3 levels and sorafenib benefit. The predictive value was assessed via Cox regression models with an interaction term. Hepatocellular carcinoma and paratumoral normal tissues were used to investigate the expression and copy-number variation of FLT3. Patient-derived xenograft (PDX) models were used to confirm the association between FLT3 levels and sorafenib response. RESULTS: Patients with FLT3-high hepatocellular carcinoma exhibited a superior OS upon sorafenib treatment. High FLT3 levels were predictive of sorafenib benefit in terms of OS (P interaction = 0.00006). Copy-number losses and decreased expression of FLT3 in hepatocellular carcinoma were detected in about 64% of patients. Moreover, the PDXs derived from tumors with high FLT3 levels also displayed a better response to sorafenib. CONCLUSIONS: Sorafenib may be able to delay tumor progression in patients with FLT3-high hepatocellular carcinoma. This potential biomarker needs to be further validated in independent cohorts prior to helping stratify patients for precision therapy in advanced hepatocellular carcinoma.

Source of dopamine in gastric juice and luminal dopamine-induced duodenal bicarbonate secretion via apical dopamine D2 receptors.

BACKGROUND AND PURPOSE: Dopamine protects the duodenal mucosa. Here we have investigated the source of dopamine in gastric juice and the mechanism underlying the effects of luminal dopamine on duodenal bicarbonate secretion (DBS) in rodents. EXPERIMENTAL APPROACH: Immunofluorescence, UPLC-MS/MS, gastric incubation and perfusion were used to detect gastric-derived dopamine. Immunofluorescence and RT-PCR were used to examine the expression of dopamine receptors in the duodenal mucosa. Real-time pH titration and pHi measurement were performed to investigate DBS. KEY RESULTS: H+ -K+ -ATPase was co-localized with tyrosine hydroxylase and dopamine transporters in gastric parietal cells. Dopamine was increased in in vivo gastric perfusate after intravenous infusion of histamine and in gastric mucosa incubated, in vitro, with bethanechol chloride or tyrosine. D2 receptors were the most abundant dopamine receptors in rat duodenum, mainly distributed on the apical membrane of epithelial cells. Luminal dopamine increased DBS in a concentration-dependent manner, an effect mimicked by a D2 receptor agonist quinpirole and inhibited by the D2 receptor antagonist L741,626, in vivo D2 receptor siRNA and in D2 receptor -/- mice. Dopamine and quinpirole raised the duodenal enterocyte pHi . Quinpirole-evoked DBS and PI3K/Akt activity were inhibited by calcium chelator BAPTA-AM or in D2 receptor-/- mice. CONCLUSION AND IMPLICATIONS: Dopamine in the gastric juice is derived from parietal cells and is secreted along with gastric acid. On arrival in the duodenal lumen, dopamine increased DBS via an apical D2 receptor- and calcium-dependent pathway. Our data provide novel insights into the protective effects of dopamine on the duodenal mucosa.

Oncofetal HLF transactivates c-Jun to promote hepatocellular carcinoma development and sorafenib resistance.

BACKGROUND AND AIMS: The unique expression pattern makes oncofetal proteins ideal diagnostic biomarkers and therapeutic targets in cancer. However, few oncofetal proteins have been identified and entered clinical practice. METHODS: Fetal liver, adult liver and hepatocellular carcinoma (HCC) tissues were employed to assess the expression of hepatic leukaemia factor (HLF). The impact of HLF on HCC onset and progression was investigated both in vivo and in vitro. The association between HLF and patient prognosis was determined in patient cohorts. The correlation between HLF expression and sorafenib benefits in HCC was further evaluated in patient cohorts and patient-derived xenografts (PDXs). RESULTS: HLF is a novel oncofetal protein which is reactivated in HCC by SOX2 and OCT4. Functional studies revealed that HLF transactivates c-Jun to promote tumour initiating cell (TIC) generation and enhances TIC-like properties of hepatoma cells, thus driving HCC initiation and progression. Consistently, our clinical investigations elucidated the association between HLF and patient prognosis and unravelled the close correlation between HLF levels and c-Jun expression in patient HCCs. Importantly, HLF/c-Jun axis determines the responses of hepatoma cells to sorafenib treatment, and interference of HLF abrogated c-Jun activation and enhanced sorafenib response. Analysis of patient cohorts and PDXs further suggests that HLF/c-Jun axis might serve as a biomarker for sorafenib benefits in HCC patients. CONCLUSIONS: Our findings uncovered HLF as a novel oncofetal protein and revealed the crucial role of the HLF/c-Jun axis in HCC development and sorafenib response, rendering HLF as an optimal target for the prevention and intervention of HCC.

The HLF/IL-6/STAT3 feedforward circuit drives hepatic stellate cell activation to promote liver fibrosis.

BACKGROUND AND AIMS: Liver fibrosis is a wound-healing response that disrupts the liver architecture and function by replacing functional parenchyma with scar tissue. Recent progress has advanced our knowledge of this scarring process, but the detailed mechanism of liver fibrosis is far from clear. METHODS: The fibrotic specimens of patients and HLF (hepatic leukemia factor)PB/PB mice were used to assess the expression and role of HLF in liver fibrosis. Primary murine hepatic stellate cells (HSCs) and human HSC line Lx2 were used to investigate the impact of HLF on HSC activation and the underlying mechanism. RESULTS: Expression of HLF was detected in fibrotic livers of patients, but it was absent in the livers of healthy individuals. Intriguingly, HLF expression was confined to activated HSCs rather than other cell types in the liver. The loss of HLF impaired primary HSC activation and attenuated liver fibrosis in HLFPB/PB mice. Consistently, ectopic HLF expression significantly facilitated the activation of human HSCs. Mechanistic studies revealed that upregulated HLF transcriptionally enhanced interleukin 6 (IL-6) expression and intensified signal transducer and activator of transcription 3 (STAT3) phosphorylation, thus promoting HSC activation. Coincidentally, IL-6/STAT3 signalling in turn activated HLF expression in HSCs, thus completing a feedforward regulatory circuit in HSC activation. Moreover, correlation between HLF expression and alpha-smooth muscle actin, IL-6 and p-STAT3 levels was observed in patient fibrotic livers, supporting the role of HLF/IL-6/STAT3 cascade in liver fibrosis. CONCLUSIONS: In aggregate, we delineate a paradigm of HLF/IL-6/STAT3 regulatory circuit in liver fibrosis and propose that HLF is a novel biomarker for activated HSCs and a potential target for antifibrotic therapy.

Purification, characterization and antitumor activity of polysaccharides extracted from Phellinus igniarius mycelia.

Water-soluble intracellular polysaccharides (IPS) were extracted from cultured mycelia of Phellinus igniarius. The IPS were purified by ethanol fractional precipitation, ion-exchange and size exclusion chromatography in that order. Homogeneous polysaccharide IPSW-1, IPSW-2, IPSW-3, and IPSW-4 were obtained, which molecular characteristics were examined using multiangle laser-light scattering and refractive index detector system. The average molecular weights of them were 34.1, 17.7, 15.1, 21.7kDa, respectively. GC analysis indicated that IPSW-1, IPSW-2 and IPSW-3 all only contained glucose, while IPSW-4 was composed of rhamnose, xylose, mannose, glucose and galactose in a molar ratio of 1.29:1.21:1:43.86:1.86. UV and IR analysis suggested they belonged to α-type of the pyran group and didn't contain protein. These homogeneous polysaccharides could inhibit the growth of SW480 and HepG2 cells to a certain extent in a dose-dependent manner. So they could be beneficial for the further development of a natural carcinoma preventive agent and functional food.