LECT2 deletion exacerbates liver steatosis and macrophage infiltration in a male mouse model of LPS-mediated NASH.

Leukocyte cell-derived chemotaxin 2 (LECT2) is a protein initially isolated as a neutrophil chemotactic factor. We previously found that LECT2 is an obesity-associated hepatokine that senses liver fat and induces skeletal muscle insulin resistance. In addition, hepatocyte-derived LECT2 activates macrophage pro-inflammatory activity by reinforcing the LPS-induced c-Jun N-terminal kinase (JNK) signaling. Based on these findings, we examined the impact of LECT2 deletion on NAFLD/NASH caused by bacterial translocation. We created the bacterial translocation-mediated NAFLD/NASH model using LECT2 knockout mice (LECT2 KO) with 28 times a low-dose LPS injection under high-fat diet feeding conditions. LECT2 deletion exacerbated steatosis and significantly reduced p38 phosphorylation in the liver. In addition, LECT2 deletion increased macrophage infiltration with decreased M1/M2 ratios. LECT2 might contribute to protecting against lipid accumulation and macrophage activation in the liver under pathological conditions, which might be accomplished via p38 phosphorylation. This study provides novel aspects of LECT2 in the bacterial translocation-mediated NAFLD/NASH model.

Diabetes Accelerates Steatohepatitis in Mice: Liver Pathology and Single-Cell Gene Expression Signatures.

Glucose lowering independently reduces liver fibrosis in human nonalcoholic fatty liver disease. This study investigated the impact of diabetes on steatohepatitis and established a novel mouse model for diabetic steatohepatitis. Male C57BL/6J mice were fed a 60% high-fat diet (HFD) and injected with carbon tetrachloride (CCl4) and streptozotocin (STZ) to induce diabetes. The HFD+CCl4+STZ group showed more severe liver steatosis, hepatocyte ballooning, and regenerative nodules compared with other groups. Diabetes up-regulated inflammatory cytokine-associated genes and increased the M1/M2 macrophage ratios in the liver. Single-cell RNA sequencing analysis of nonparenchymal cells in the liver showed that diabetes reduced Kupffer cells and increased bone marrow-derived recruited inflammatory macrophages, such as Ly6Chi-RM. Diabetes globally reduced liver sinusoidal endothelial cells (LSECs). Furthermore, genes related to the receptor for advanced glycation end products (RAGE)/Toll-like receptor 4 (TLR4) were up-regulated in Ly6Chi-RM and LSECs in mice with diabetes, suggesting a possible role of RAGE/TLR4 signaling in the interaction between inflammatory macrophages and LSECs. This study established a novel diabetic steatohepatitis model using a combination of HFD, CCl4, and STZ. Diabetes exacerbated steatosis, hepatocyte ballooning, fibrosis, regenerative nodule formation, and the macrophage M1/M2 ratios triggered by HFD and CCl4. Single-cell RNA sequencing analysis indicated that diabetes activated inflammatory macrophages and impairs LSECs through the RAGE/TLR4 signaling pathway. These findings open avenues for discovering novel therapeutic targets for diabetic steatohepatitis.

Relationship between the changes in hepatokine levels and metabolic effects after laparoscopic sleeve gastrectomy in severely obese patients.

PURPOSE: To clarify the relationships between the changes in hepatokines and weight loss, and between these changes and the metabolic effects, and the roles played by these changes, after laparoscopic sleeve gastrectomy (LSG). METHODS: We recruited 25 Japanese patients with severe obesity, who underwent LSG. We measured two hepatokines: selenoprotein P (SeP) and leukocyte cell-derived chemotaxin 2 (LECT2), at the baseline, and then 6 months and 1 year after LSG. Finally, we compared the changes in the hepatokines with the parameters of type 2 diabetes (T2D) and non-alcoholic steatohepatitis (NASH). RESULTS: Changes in LECT2 were correlated with the percentage of total weight loss (ρ = - 0.499, P = 0.024) and the decrease in total fat area (ρ = 0.559, P = 0.003). The changes in SeP were correlated with those in hemoglobin A1c (ρ = 0.526, P = 0.043) and the insulinogenic index (ρ = 0.638, P = 0.010) in T2D patients. In patients with NASH, the LECT2 levels were correlated with liver steatosis (ρ = 0.601). CONCLUSIONS: SeP levels decrease in association with HbA1c reduction, whereas LECT2 levels are associated with reductions in fat mass and NASH scores after LSG. Hepatokines may be involved in the pathology of obesity and its complications.

Trajectories of Liver Fibrosis and Gene Expression Profiles in Nonalcoholic Fatty Liver Disease Associated With Diabetes.

Understanding the mechanisms linking steatosis to fibrosis is needed to establish a promising therapy against nonalcoholic fatty liver disease (NAFLD). The aim of this study was to clarify clinical features and hepatic gene expression signatures that predict and contribute to liver fibrosis development during the long-term real-world histological course of NAFLD in subjects with and without diabetes. A pathologist scored 342 serial liver biopsy samples from 118 subjects clinically diagnosed with NAFLD during a 3.8-year (SD 3.45 years, maximum 15 years) course of clinical treatment. At the initial biopsy, 26 subjects had simple fatty liver, and 92 had nonalcoholic steatohepatitis (NASH). In the trend analysis, the fibrosis-4 index (P < 0.001) and its components at baseline predicted the future fibrosis progression. In the generalized linear mixed model, an increase in HbA1c, but not BMI, was significantly associated with fibrosis progression (standardized coefficient 0.17 [95% CI 0.009-0.326]; P = 0.038) for subjects with NAFLD and diabetes. In gene set enrichment analyses, the pathways involved in zone 3 hepatocytes, central liver sinusoidal endothelial cells (LSECs), stellate cells, and plasma cells were coordinately altered in association with fibrosis progression and HbA1c elevation. Therefore, in subjects with NAFLD and diabetes, HbA1c elevation was significantly associated with liver fibrosis progression, independent of weight gain, which may be a valuable therapeutic target to prevent the pathological progression of NASH. Gene expression profiles suggest that diabetes-induced hypoxia and oxidative stress injure LSECs in zone 3 hepatocytes, which may mediate inflammation and stellate cell activation, leading to liver fibrosis. ARTICLE HIGHLIGHTS: It remains uncertain how diabetes and obesity contribute to histological courses of nonalcoholic fatty liver disease (NAFLD). Clinical features and gene expression signatures that predict or are associated with future liver fibrosis development were assessed in a serial liver biopsy study of subjects with NAFLD. An increase in HbA1c, but not BMI, was associated with liver fibrosis progression in the generalized linear mixed model. Considering hepatic gene set enrichment analyses, diabetes may enhance liver fibrosis via injuring central liver sinusoidal endothelial cells that mediate inflammation and stellate cell activation during NAFLD development.

PAC1 Deficiency Protects Obese Male Mice From Immobilization-Induced Muscle Atrophy by Suppressing FoxO-Atrogene Axis.

Muscle atrophy is the cause and consequence of obesity. Proteasome dysfunction mediates obesity-induced endoplasmic reticulum (ER) stress and insulin resistance in the liver and adipose tissues. However, obesity-associated regulation of proteasome function and its role in the skeletal muscles remains underinvestigated. Here, we established skeletal muscle-specific 20S proteasome assembly chaperone-1 (PAC1) knockout (mPAC1KO) mice. A high-fat diet (HFD) activated proteasome function by ∼8-fold in the skeletal muscles, which was reduced by 50% in mPAC1KO mice. mPAC1KO induced unfolded protein responses in the skeletal muscles, which were reduced by HFD. Although the skeletal muscle mass and functions were not different between the genotypes, genes involved in the ubiquitin proteasome complex, immune response, endoplasmic stress, and myogenesis were coordinately upregulated in the skeletal muscles of mPAC1KO mice. Therefore, we introduced an immobilization-induced muscle atrophy model in obesity by combining HFD and immobilization. mPAC1KO downregulated atrogin-1 and MuRF1, together with their upstream Foxo1 and Klf15, and protected against disused skeletal muscle mass reduction. In conclusion, obesity elevates proteasome functions in the skeletal muscles. PAC1 deficiency protects mice from immobilization-induced muscle atrophy in obesity. These findings suggest obesity-induced proteasome activation as a possible therapeutic target for immobilization-induced muscle atrophy.

Predictive value of prostate calcification for future cancer occurrence: a retrospective long-term follow-up cohort study.

OBJECTIVE: Although prostate calcification is often identified on pelvic CT images, calcification itself is usually not considered clinically significant. A recent histological study proposed an association between prostate calcification and prostate cancer occurrence. Our aim was to determine the predictive value of prostate calcifications for future prostate cancer occurrence. METHODS: We retrospectively analysed male patients (≥50 years old) without prior prostate cancer history, who underwent unenhanced pelvic CT between April 2010 and March 2011, and followed-up until December 2021. Cox proportional hazards models were used to assess prostate cancer risk with prostate calcification (defined as a high-density area larger than 3 mm with CT attenuation values ≥ 130 HU), controlling for age, body mass index (BMI), hypertension and diabetes mellitus. RESULTS: A total of 636 male patients (mean age, 68 years ± 9 [standard deviation]) were evaluated. At the end of follow-up, prostate cancer had been more frequently diagnosed in patients with prostate calcification than those without prostate calcification (6.5% vs 2.6%). Multivariate analysis revealed that prostate calcification on CT was a significant predictor of future prostate cancer occurrence (hazard ratio [HR], 2.7; 95% CI: 1.20, 5.91; p = 0.016). No statistical differences were observed in any other factors. CONCLUSION: Prostate calcification may be a significant predictor of future prostate cancer occurrence, and may be used for risk stratification and to guide screening protocols. ADVANCES IN KNOWLEDGE: Presence of prostate calcification on unenhanced CT scan was associated with increased incidence of prostate cancer occurrence on long term follow-up.

Selenoprotein P deficiency protects against immobilization-induced muscle atrophy by suppressing atrophy-related E3 ubiquitin ligases.

The quality of skeletal muscle is maintained by a balance between protein biosynthesis and degradation. Disruption in this balance results in sarcopenia. However, its underlying mechanisms remain underinvestigated. Selenoprotein P (SeP; encoded by Selenop in mice) is a hepatokine that is upregulated in type 2 diabetes and aging and causes signal resistances via reductive stress. We created immobilized muscle atrophy model in Selenop knockout (KO) mice. Immobilization (IMM) significantly reduced cross-sectional areas and the size of skeletal muscle fibers, which were ameliorated in KO mice. IMM upregulated the genes encoding E3 ubiquitin ligases and their upstream FoxO1, FoxO3, and KLF15 transcription factors in the skeletal muscle, which were suppressed in KO mice. These findings suggest a possible involvement of SeP-mediated reductive stress in physical inactivity-mediated sarcopenia, which may be a therapeutic target against sarcopenia.NEW & NOTEWORTHY Selenoprotein P (SeP) is a hepatokine that is upregulated in type 2 diabetes and aging and causes signal resistances via reductive stress. Immobilization (IMM) significantly reduced skeletal muscle mass in mice, which was prevented in SeP knockout (KO) mice. IMM-induced Foxos/KLF15-atrogene upregulation was suppressed in the skeletal muscle of KO mice. These findings suggest that SeP-mediated reductive stress is involved in and may be a therapeutic target for physical inactivity-mediated muscle atrophy.

Insulin Suppresses Ubiquitination via the Deubiquitinating Enzyme Ubiquitin-Specific Protease 14, Independent of Proteasome Activity in H4IIEC3 Hepatocytes.

Ubiquitin-proteasome dysfunction contributes to obesity-related metabolic disorders, such as diabetes and fatty liver disease. However, the regulation of ubiquitin-proteasome activity by insulin remains to be elucidated. Here, we show that prolonged insulin stimulation activates proteasome function even though it reduces the ubiquitinated proteins in H4IIEC3 hepatocytes. Looking for a pathway by which insulin inhibits ubiquitination, we found that hepatic expression of ubiquitin-specific protease 14 (USP14) was upregulated in the liver of patients with insulin resistance. Indeed, the USP14-specific inhibitor IU1 canceled the insulin-mediated reduction of ubiquitinated proteins. Furthermore, insulin-induced endoplasmic reticulum (ER) stress, which was canceled by IU1, suggesting that USP14 activity is involved in insulin-induced ER stress. Co-stimulation with insulin and IU1 for 2 hours upregulated the nuclear translocation of the lipogenic transcription factor, sterol regulatory element binding protein-1c (SREBP-1c), upregulated the expression of the lipogenic gene, fatty acid synthase (Fasn), and repressed the gluconeogenic genes. In conclusion, insulin activates proteasome function even though it inhibits protein ubiquitination by activating USP14 in hepatocytes. USP14 activation by insulin inhibits mature SREBP-1c while upregulating ER stress and the expression of genes involved in gluconeogenesis. Further understanding mechanisms underlying the USP14 activation and its pleiotropic effects may lead to therapeutic development for obesity-associated metabolic disorders, such as diabetes and fatty liver disease. SIGNIFICANCE STATEMENT: This study shows that insulin stimulation inhibits ubiquitination by activating USP14, independent of its effect on proteasome activity in hepatocytes. USP14 also downregulates the nuclear translocation of the lipogenic transcription factor SREBP-1c and upregulates the expression of genes involved in gluconeogenesis. Since USP14 is upregulated in the liver of insulin-resistant patients, understanding mechanisms underlying the USP14 activation and its pleiotropic effects will help develop treatments for metabolic disorders such as diabetes and fatty liver.

Circulating selenoprotein P levels predict glucose-lowering and insulinotropic effects of metformin, but not alogliptin: A post-hoc analysis.

AIMS/INTRODUCTION: Selenoprotein P (SeP; encoded by SEPP1 in humans) is a hepatokine that causes impaired insulin secretion and insulin resistance. Metformin downregulates SELENOP promoter activity through an adenosine monophosphate-activated kinase-forkhead box protein O3a pathway in hepatocytes. This study aimed to test our hypothesis that circulating SeP levels are associated with the glucose-lowering effect of metformin in humans. MATERIALS AND METHODS: A total of 84 participants with poorly controlled type 2 diabetes were randomly assigned to receive metformin (1,000 mg, twice daily) or a dipeptidyl peptidase-4 inhibitor, alogliptin (25 mg, once daily) for 12 weeks. We tested metformin and alogliptin on SeP levels and factors associated therewith as a post-hoc analysis. RESULTS: Both metformin and aloglipitin did not change the SeP levels. Although metformin significantly increased the insulin secretory index secretory units of islets in transplantation only in participants with higher baseline SeP (>3.87), both agents similarly reduced fasting plasma glucose and glycated hemoglobin. SeP levels at baseline were correlated negatively with changes in SeP (r = -0.484, P = 0.004) and fasting plasma glucose (r = -0.433, P = 0.011), and positively with changes in C-peptide immunoreactivity (r = 0.420, P = 0.017) and secretory units of islets in transplantation (r = 0.388, P = 0.028) in the metformin, but not alogliptin, group. CONCLUSIONS: Higher baseline levels of SeP significantly predicted metformin-mediated, but not alogliptin-mediated, glucose-lowering and insulinotropic effects. Serum SeP levels might be a novel biomarker for predicting the outcomes of metformin therapy, which might be helpful in tailoring diabetes medication.

Cyclosporine A Downregulates Selenoprotein P Expression via a Signal Transducer and Activator of Transcription 3-Forkhead Box Protein O1 Pathway in Hepatocytes In Vitro.

Cyclosporine A (CsA) is an immunosuppressant applied worldwide for preventing graft rejection and autoimmune diseases. However, CsA elevates oxidative stress, which can lead to liver injuries. The present study aimed to clarify the mechanisms underlying the CsA-mediated oxidative stress. Among the redox proteins, CsA concentration-dependently downregulated Selenop-encoding selenoprotein P, a major circulating antioxidant protein reducing reactive oxygen species, in hepatocytes cell lines and primary hepatocytes. The luciferase assay identified the CsA-responsive element in the SELENOP promoter containing a putative binding site for forkhead box protein O (FoxO) 1. The CsA-mediated suppression on the SELENOP promoter was independent of the nuclear factor of activated T-cell, a classic target repressed by CsA. A chromatin immunoprecipitation assay showed that CsA suppressed the FoxO1 binding to the SELENOP promoter. Foxo1 knockdown significantly downregulated Selenop expression in H4IIEC3 cells. Furthermore, CsA downregulated FoxO1 by inactivating its upstream signal transducer and activator of transcription 3 (STAT3). Knockdown of Stat3 downregulated Foxo1 and Selenop expression in hepatocytes. These findings revealed a novel mechanism underlying CsA-induced oxidative stress by downregulating the STAT3-FoxO1-Selenop pathway in hepatocytes. SIGNIFICANCE STATEMENT: This study shows that Cyclosporine A (CsA) downregulates Selenop, an antioxidant protein, by suppressing the signal transducer and activator of transcription 3-forkhead box protein O1 pathway in hepatocytes, possibly one of the causations of CsA-induced oxidative stress in hepatocytes. The present study sheds light on the previously unrecognized CsA-redox axis.

Leukocyte cell-derived chemotaxin 2 is an antiviral regulator acting through the proto-oncogene MET.

Retinoic acid-inducible gene (RIG)-I is an essential innate immune sensor that recognises pathogen RNAs and induces interferon (IFN) production. However, little is known about how host proteins regulate RIG-I activation. Here, we show that leukocyte cell-derived chemotaxin 2 (LECT2), a hepatokine and ligand of the MET receptor tyrosine kinase is an antiviral regulator that promotes the RIG-I-mediated innate immune response. Upon binding to MET, LECT2 induces the recruitment of the phosphatase PTP4A1 to MET and facilitates the dissociation and dephosphorylation of phosphorylated SHP2 from MET, thereby protecting RIG-I from SHP2/c-Cbl-mediated degradation. In vivo, LECT2 overexpression enhances RIG-I-dependent IFN production and inhibits lymphocytic choriomeningitis virus (LCMV) replication in the liver, whereas these changes are reversed in LECT2 knockout mice. Forced suppression of MET abolishes IFN production and antiviral activity in vitro and in vivo. Interestingly, hepatocyte growth factor (HGF), an original MET ligand, inhibits LECT2-mediated anti-viral signalling; conversely, LECT2-MET signalling competes with HGF-MET signalling. Our findings reveal previously unrecognized crosstalk between MET-mediated proliferation and innate immunity and suggest that targeting LECT2 may have therapeutic value in infectious diseases and cancer.

Lauric acid impairs insulin-induced Akt phosphorylation by upregulating SELENOP expression via HNF4α induction.

Selenoprotein P (SeP; encoded by SELENOP in humans, Selenop in rodents) is a hepatokine that is upregulated in the liver of humans with type 2 diabetes. Excess SeP contributes to the onset of insulin resistance and various type 2 diabetes-related complications. We have previously reported that the long-chain saturated fatty acid, palmitic acid, upregulates Selenop expression, whereas the polyunsaturated fatty acids (PUFAs) downregulate it in hepatocytes. However, the effect of medium-chain fatty acids (MCFAs) on Selenop is unknown. Here we report novel mechanisms that underlie the lauric acid-mediated Selenop gene regulation in hepatocytes. Lauric acid upregulated Selenop expression in Hepa1-6 hepatocytes and mice liver. A luciferase promoter assay and computational analysis of transcription factor-binding sites identified the hepatic nuclear factor 4α (HNF4α) binding site in the SELENOP promoter. A chromatin immunoprecipitation (ChIP) assay showed that lauric acid increased the binding of HNF4α to the SELENOP promoter. The knockdown of Hnf4α using siRNA canceled the upregulation of lauric acid-induced Selenop. Thus, the lauric acid-induced impairment of Akt phosphorylation brought about by insulin was rescued by the knockdown of either Hnf4α or Selenop. These results provide new insights into the regulation of SeP by fatty acids and suggest that SeP may mediate MCFA-induced hepatic insulin signal reduction.

Selenoprotein P-mediated reductive stress impairs cold-induced thermogenesis in brown fat.

Reactive oxygen species (ROS) activate uncoupler protein 1 (UCP1) in brown adipose tissue (BAT) under physiological cold exposure and noradrenaline (NA) stimulation to increase thermogenesis. However, the endogenous regulator of ROS in activated BAT and its role in pathological conditions remain unclear. We show that serum levels of selenoprotein P (SeP; encoded by SELENOP) negatively correlate with BAT activity in humans. Physiological cold exposure downregulates Selenop in BAT. Selenop knockout mice show higher rectal temperatures and UCP1 sulfenylation during cold exposure. SeP treatment to brown adipocytes eliminated the NA-induced mitochondrial ROS by upregulating glutathione peroxidase 4 and impaired cellular thermogenesis. A high-fat/high-sucrose diet elevates serum SeP levels and diminishes the elevated NA-induced thermogenesis in BAT-Selenop KO mice. Therefore, SeP is the intrinsic factor inducing reductive stress that impairs thermogenesis in BAT and may be a potential therapeutic target for obesity and diabetes.

Forkhead box protein O1 (FoxO1) knockdown accelerates the eicosapentaenoic acid (EPA)-mediated Selenop downregulation independently of sterol regulatory element-binding protein-1c (SREBP-1c) in H4IIEC3 hepatocytes.

Selenoprotein P is upregulated in type 2 diabetes, causing insulin and exercise resistance. We have previously reported that eicosapentaenoic acid (EPA) negatively regulates Selenop expression by suppressing Srebf1 in H4IIEC3 hepatocytes. However, EPA downregulated Srebf1 long before downregulating Selenop. Here, we report additional novel mechanisms for the Selenop gene regulation by EPA. EPA upregulated Foxo1 mRNA expression, which was canceled with the ERK1/2 inhibitor, but not with the PKA inhibitor. Foxo1 knockdown by siRNA initiated early suppression of Selenop, but not Srebf1, by EPA. However, EPA did not affect the nuclear translocation of the FoxO1 protein. Neither ERK1/2 nor PKA inhibitor affected FoxO1 nuclear translocation. In summary, FoxO1 knockdown accelerates the EPA-mediated Selenop downregulation independent of SREBP-1c in hepatocytes. EPA upregulates Foxo1 mRNA via the ERK1/2 pathway without altering its protein and nuclear translocation. These findings suggest redundant and conflicting transcriptional networks in the lipid-induced redox regulation.

Effects of eicosapentaenoic acid on serum levels of selenoprotein P and organ-specific insulin sensitivity in humans with dyslipidemia and type 2 diabetes.

AIM: Selenoprotein P (SeP, encoded by SELENOP in humans) is a hepatokine that causes insulin resistance in the liver and skeletal muscle. It was found that polyunsaturated fatty acid eicosapentaenoic acid (EPA) downregulates Selenop expression by inactivating SREBP-1c. The present study aimed to examine the effect of EPA for 12 weeks on circulating SeP levels and insulin sensitivity in humans with type 2 diabetes. METHODS: A total of 20 participants with dyslipidemia and type 2 diabetes were randomly assigned to an EPA (900 mg, twice daily) group and a control group. The primary endpoint was a change in serum SeP levels. Organ-specific insulin sensitivity in the liver (HGP and %HGP), skeletal muscle (Rd), and adipose tissue (FFA and %FFA) were assessed using a hyperinsulinemic-euglycemic clamp study with stable isotope-labeled glucose infusion. RESULTS: Serum SeP levels were not changed in either group at the end of the study. In the EPA group, the changes in SeP levels were positively correlated with the change in serum EPA levels (r = 0.709, P = 0.022). Treatment with EPA significantly enhanced %FFA but not %HGP and Rd. The change in serum EPA levels was significantly positively correlated with the change in %HGP, and negatively correlated with changes in Rd. CONCLUSIONS: The change in serum EPA levels was positively correlated with serum SeP levels, hepatic insulin sensitivity, and negatively with skeletal muscle insulin sensitivity in humans with type 2 diabetes. The EPA-induced enhancement of hepatic insulin sensitivity might be associated with a mechanism independent of serum SeP levels.

Corrigendum: Alcohol Intake Is Associated With Elevated Serum Levels of Selenium and Selenoprotein P in Humans.

[This corrects the article DOI: 10.3389/fnut.2021.633703.].

Alcohol Intake Is Associated With Elevated Serum Levels of Selenium and Selenoprotein P in Humans.

Selenoprotein P is a hepatokine with antioxidative properties that eliminate a physiologic burst of reactive oxygen species required for intracellular signal transduction. Serum levels of selenoprotein P are elevated during aging and in people with type 2 diabetes, non-alcoholic fatty liver disease, and hepatitis C. However, how serum levels of full-length selenoprotein P are regulated largely remains unknown, especially in the general population. To understand the significance of serum selenoprotein P levels in the general population, we evaluated intrinsic and environmental factors associated with serum levels of full-length selenoprotein P in 1,183 subjects participating in the Shika-health checkup cohort. Serum levels of selenium were positively correlated with liver enzymes and alcohol intake and negatively correlated with body mass index. Serum levels of selenoprotein P were positively correlated with age, liver enzymes, and alcohol intake. In multiple regression analyses, alcohol intake was positively correlated with serum levels of both selenium and selenoprotein P independently of age, gender, liver enzymes, and fatty liver on ultrasonography. In conclusion, alcohol intake is associated with elevated serum levels of selenium and selenoprotein P independently of liver enzyme levels and liver fat in the general population. Moderate alcohol intake may exert beneficial or harmful effects on health, at least partly by upregulating selenoprotein P. These findings increase our understanding of alcohol-mediated redox regulation and form the basis for the adoption of appropriate drinking guidelines.

LECT2 as a hepatokine links liver steatosis to inflammation via activating tissue macrophages in NASH.

It remains unclear how hepatic steatosis links to inflammation. Leukocyte cell-derived chemotaxin 2 (LECT2) is a hepatokine that senses fat in the liver and is upregulated prior to weight gain. The aim of this study was to investigate the significance of LECT2 in the development of nonalcoholic steatohepatitis (NASH). In human liver biopsy samples, elevated LECT2 mRNA levels were positively correlated with body mass index (BMI) and increased in patients who have steatosis and inflammation in the liver. LECT2 mRNA levels were also positively correlated with the mRNA levels of the inflammatory genes CCR2 and TLR4. In C57BL/6J mice fed with a high-fat diet, mRNA levels of the inflammatory cytokines Tnfa and Nos2 were significantly lower in Lect2 KO mice. In flow cytometry analyses, the number of M1-like macrophages and M1/M2 ratio were significantly lower in Lect2 KO mice than in WT mice. In KUP5, mouse kupffer cell line, LECT2 selectively enhanced the LPS-induced phosphorylation of JNK, but not that of ERK and p38. Consistently, LECT2 enhanced the LPS-induced phosphorylation of MKK4 and TAB2, upstream activators of JNK. Hepatic expression of LECT2 is upregulated in association with the inflammatory signature in human liver tissues. The elevation of LECT2 shifts liver residual macrophage to the M1-like phenotype, and contributes to the development of liver inflammation. These findings shed light on the hepatokine LECT2 as a potential therapeutic target that can dissociate liver steatosis from inflammation.

Plasma half-life and tissue distribution of leukocyte cell-derived chemotaxin 2 in mice.

Leukocyte cell-derived chemotaxin 2 (LECT2) is a hepatokine that causes skeletal muscle insulin resistance. The circulating levels of LECT2 are a possible biomarker that can predict weight cycling because they reflect liver fat and precede the onset of weight loss or gain. Herein, to clarify the dynamics of this rapid change in serum LECT2 levels, we investigated the in vivo kinetics of LECT2, including its plasma half-life and tissue distribution, by injecting 125I-labelled LECT2 into ICR mice and radioactivity tracing. The injected LECT2 was eliminated from the bloodstream within 10 min (approximate half-life, 5 min). In the kidneys, the radioactivity accumulated within 10 min after injection and declined thereafter. Conversely, the radioactivity in urine increased after 30 min of injection, indicating that LECT2 is mainly excreted by the kidneys into the urine. Finally, LECT2 accumulated in the skeletal muscle and liver until 30 min and 2 min after injection, respectively. LECT2 accumulation was not observed in the adipose tissue. These findings are in agreement with LECT2 action on the skeletal muscle. The present study indicates that LECT2 is a rapid-turnover protein, which renders the circulating level of LECT2 a useful rapid-response biomarker to predict body weight alterations.

Acute Hyperenergetic, High-Fat Feeding Increases Circulating FGF21, LECT2, and Fetuin-A in Healthy Men.

BACKGROUND: Hepatokines such as fibroblast growth factor 21 (FGF21), leukocyte cell-derived chemotaxin 2 (LECT2), fetuin-A, fetuin-B, and selenoprotein P (SeP) are liver-derived proteins that are modulated by chronic energy status and metabolic disease. Emerging data from rodent and cell models indicate that hepatokines may be sensitive to acute nutritional manipulation; however, data in humans are lacking. OBJECTIVE: The aim was to investigate the influence of hyperenergetic, high-fat feeding on circulating hepatokine concentrations, including the time course of responses. METHODS: In a randomized, crossover design, 12 healthy men [mean ± SD: age, 24 ± 4 y; BMI (kg/m2), 24.1 ± 1.5] consumed a 7-d hyperenergetic, high-fat diet [HE-HFD; +50% energy, 65% total energy as fat (32% saturated, 26% monounsaturated, 8% polyunsaturated)] and control diet (36% total energy as fat), separated by 3 wk. Whole-body insulin sensitivity was assessed before and after each diet using oral-glucose-tolerance tests. Fasting plasma concentrations of FGF21 (primary outcome), LECT2, fetuin-A, fetuin-B, SeP, and related metabolites were measured after 1, 3, and 7 d of each diet. Hepatokine responses were analyzed using 2-factor repeated-measures ANOVA and subsequent pairwise comparisons. RESULTS: Compared with the control, the HE-HFD increased circulating FGF21 at 1 d (105%) and 3 d (121%; P ≤ 0.040), LECT2 at 3 d (17%) and 7 d (32%; P ≤ 0.004), and fetuin-A at 7 d (7%; P = 0.028). Plasma fetuin-B and SeP did not respond to the HE-HFD. Whole-body insulin sensitivity was reduced after the HE-HFD by 31% (P = 0.021). CONCLUSIONS: Acute high-fat overfeeding augments circulating concentrations of FGF21, LECT2, and fetuin-A in healthy men. Notably, the time course of response varies between proteins and is transient for FGF21. These findings provide further insight into the nutritional regulation of hepatokines in humans and their interaction with metabolic homeostasis. This study was registered at clinicaltrials.gov as NCT03369145.