Carnosol inhibits cerebral ischemia-reperfusion injury by promoting AMPK activation

BACKGROUND

Carnosol is a phytopolyphenol (diterpene) found and extracted from plants of Mediterranean diet, which has anti-tumor, anti-inflammatory and antioxidant effects. However, its role in ischemic stroke has not been elucidated.

METHODS

Primary neurons subjected to oxygen-glucose deprivation (OGD) was used to investigate the effect of carnosol in vitro. A mouse MCAO model was used to evaluate the effect of carnosol on ischemic stroke in vivo. The mRNA level of inflammatory and apoptosis-related genes was determined by RT-PCR. The protein level of total and phosphorylated AMPK was determined by WB. H&E and Immunofluorescent assay was used to investigate the necrosis, inflammation and apoptosis in brain tissue.

RESULTS

Carnosol protected the activity of primary neurons subjected to oxygen-glucose deprivation (OGD) in vitro, as well as inhibited inflammation and apoptosis. Furthermore, carnosol could significantly reduce the infarct and edema volume and protect against neurological deficit in vivo, and had a significant inhibitory effect on brain neuroinflammation and apoptosis. Mechanically, carnosol could activate AMPK, and the effect of carnosol on cerebral ischemia-reperfusion injury cell model could be abolished by AMPK phosphorylation inhibitor.

CONCLUSION

Carnosol has a protective effect on ischemic stroke, and this effect is achieved through AMPK activation. Our study demonstrates the protective effect of carnosol on cerebral ischemia-reperfusion injury and provides a new perspective for the clinical treatment of ischemic stroke.

A high-throughput drug screening identifies luteolin as a therapeutic candidate for pathological cardiac hypertrophy and heart failure

Background

Pathological cardiac hypertrophy is commonly resulted from sustained pressure overload and/or metabolic disorder and eventually leads to heart failure, lacking specific drugs in clinic. Here, we aimed to identify promising anti-hypertrophic drug(s) for heart failure and related metabolic disorders by using a luciferase reporter-based high-throughput screening.

Methods

A screen of the FDA-approved compounds based on luciferase reporter was performed, with identified luteolin as a promising anti-hypertrophic drug. We systematically examined the therapeutic efficacy of luteolin on cardiac hypertrophy and heart failure in vitro and in vivo models. Transcriptome examination was performed to probe the molecular mechanisms of luteolin.

Results

Among 2,570 compounds in the library, luteolin emerged as the most robust candidate against cardiomyocyte hypertrophy. Luteolin dose-dependently blocked phenylephrine-induced cardiomyocyte hypertrophy and showed extensive cardioprotective roles in cardiomyocytes as evidenced by transcriptomics. More importantly, gastric administration of luteolin effectively ameliorated pathological cardiac hypertrophy, fibrosis, metabolic disorder, and heart failure in mice. Cross analysis of large-scale transcriptomics and drug-target interacting investigations indicated that peroxisome proliferator activated receptor γ (PPARγ) was the direct target of luteolin in the setting of pathological cardiac hypertrophy and metabolic disorders. Luteolin can directly interact with PPARγ to inhibit its ubiquitination and subsequent proteasomal degradation. Furthermore, PPARγ inhibitor and PPARγ knockdown both prevented the protective effect of luteolin against phenylephrine-induced cardiomyocyte hypertrophy in vitro.

Conclusion

Our data clearly supported that luteolin is a promising therapeutic compound for pathological cardiac hypertrophy and heart failure by directly targeting ubiquitin-proteasomal degradation of PPARγ and the related metabolic homeostasis.

Effects of treatment of non-alcoholic fatty liver disease on heart failure with preserved ejection fraction

In the past few decades, non-alcoholic fatty liver disease (NAFLD) and heart failure with preserved ejection fraction (HFpEF) have become the most common chronic liver disease and the main form of heart failure (HF), respectively. NAFLD is closely associated with HFpEF by sharing common risk factors and/or by boosting systemic inflammation, releasing other secretory factors, and having an expansion of epicardial adipose tissue (EAT). Therefore, the treatments of NAFLD may also affect the development and prognosis of HFpEF. However, no specific drugs for NAFLD have been approved by the Food and Drug Administration (FDA) and some non-specific treatments for NAFLD are applied in the clinic. Currently, the treatments of NAFLD can be divided into non-pharmacological and pharmacological treatments. Non-pharmacological treatments mainly include dietary intervention, weight loss by exercise, caloric restriction, and bariatric surgery. Pharmacological treatments mainly include administering statins, thiazolidinediones, glucagon-like peptide-1 receptor agonists, sodium-glucose cotransporter 2 inhibitors, and metformin. This review will mainly focus on analyzing how these treatments may affect the development and prognosis of HFpEF.

The nonlinear relationship between thyroid function parameters and metabolic dysfunction-associated fatty liver disease

BACKGROUND

The relationship between thyroid function parameters and metabolic dysfunction-associated fatty liver disease (MAFLD) remains controversial. Additionally, little is known about the relationship between thyroid function parameters and MAFLD in the Chinese population.

METHODS

We conducted a retrospective cross-sectional study involving 177,540 individuals with thyroid function tests and MAFLD diagnosis from 2010-2018. The association between thyroid function parameters and MAFLD was evaluated on a continuous scale with restricted cubic spline (RCS) models and by the prior-defined centile categories with multivariable-adjusted logistic regression models. Thyroid function parameters included free triiodothyronine (FT3), free tetra-iodothyronine (FT4), and thyroid stimulating hormone (TSH). Additionally, fully adjusted RCS models stratified by sex, age, and location were studied.

RESULTS

In the RCS models, the risk of MAFLD increased with higher levels of FT3 when FT3 <5.58pmol/L, while the risk of MAFLD decreased with higher levels of FT3 when FT3 ≥5.58pmol/L (P nonlinearity <0.05). While RCS analysis suggested that the FT4 levels had a negative association with MAFLD (P nonlinearity <0.05), indicating an increase in FT4 levels was associated with a decreased risk of MAFLD. RCS analysis suggested an overall positive association between the concentration of TSH and MAFLD risk (P nonlinearity <0.05). The rising slope was sharper when the TSH concentration was less than 1.79uIU/mL, which indicated the association between TSH and MAFLD risk was tightly interrelated within this range. The multivariable logistic regression showed that populations in the 81st-95th centile had the highest risk of MAFLD among all centiles of FT3/TSH, with the 1st-5th centile as the reference category.

CONCLUSIONS

Our study suggested nonlinear relationships between thyroid function parameters and MAFLD. Thyroid function parameters could be additional modifiable risk factors apart from the proven risk factors to steer new avenues regarding MAFLD prevention and treatment.

The projections of global and regional rheumatic heart disease burden from 2020 to 2030

Background

Rheumatic heart disease (RHD) remains the leading cause of preventable death and disability in children and young adults, killing an estimated 320,000 individuals worldwide yearly.

Materials and methods

We utilized the Bayesian age-period cohort (BAPC) model to project the change in disease burden from 2020 to 2030 using the data from the Global Burden of Disease (GBD) Study 2019. Then we described the projected epidemiological characteristics of RHD by region, sex, and age.

Results

The global age-standardized prevalence rate (ASPR) and age-standardized incidence rate (ASIR) of RHD increased from 1990 to 2019, and ASPR will increase to 559.88 per 100,000 population by 2030. The global age-standardized mortality rate (ASMR) of RHD will continue declining, while the projected death cases will increase. Furthermore, ASPR and cases of RHD-associated HF will continue rising, and there will be 2,922,840 heart failure (HF) cases in 2030 globally. Female subjects will still be the dominant population compared to male subjects, and the ASPR of RHD and the ASPR of RHD-associated HF in female subjects will continue to increase from 2020 to 2030. Young people will have the highest ASPR of RHD among all age groups globally, while the elderly will bear a greater death and HF burden.

Conclusion

In the following decade, the RHD burden will remain severe. There are large variations in the trend of RHD burden by region, sex, and age. Targeted and effective strategies are needed for the management of RHD, particularly in female subjects and young people in developing regions.

The contribution of the gut-liver axis to the immune signaling pathway of NAFLD

Nonalcoholic fatty liver disease (NAFLD) is the liver manifestation of metabolic syndrome and is the most common chronic liver disease in the world. The pathogenesis of NAFLD has not been fully clarified; it involves metabolic disturbances, inflammation, oxidative stress, and various forms of cell death. The “intestinal-liver axis” theory, developed in recent years, holds that there is a certain relationship between liver disease and the intestinal tract, and changes in intestinal flora are closely involved in the development of NAFLD. Many studies have found that the intestinal flora regulates the pathogenesis of NAFLD by affecting energy metabolism, inducing endotoxemia, producing endogenous ethanol, and regulating bile acid and choline metabolism. In this review, we highlighted the updated discoveries in intestinal flora dysregulation and their link to the pathogenesis mechanism of NAFLD and summarized potential treatments of NAFLD related to the gut microbiome.

Profound Perturbation in the Metabolome of a Canine Obesity and Metabolic Disorder Model

Canine models are increasingly being used in metabolic studies due to their physiological similarity with humans. The present study aimed to identify changes in metabolic pathways and biomarkers with potential clinical utility in a canine model of obesity and metabolic disorders induced by a high-fat diet (HFD). Eighteen male beagles were included in this study, 9 of which were fed a HFD for 24 weeks, and the remaining 9 were fed normal chow (NC) during the same period. Plasma and urine samples were collected at weeks 12 and 24 for untargeted metabolomic analysis. Dogs fed a HFD showed a gradual body weight increase during the feeding period and had hyperlipidemia, increased leukocyte counts, and impaired insulin sensitivity at week 24. Plasma and urine metabonomics analysis displayed clear separations between the HFD-fed and NC-fed dogs. A total of 263 plasma metabolites varied between the two groups, including stearidonic acid, linolenic acid, carnitine, long-chain ceramide, 3-methylxanthine, and theophylline, which are mainly engaged in fatty acid metabolism, sphingolipid metabolism, and caffeine metabolism. A total of 132 urine metabolites related to HFD-induced obesity and metabolic disorders were identified, including 3-methylxanthine, theophylline, pyridoxal 5'-phosphate, and harmine, which participate in pathways such as caffeine metabolism and vitamin digestion and absorption. Eight metabolites with increased abundance (e.g., 3-methylxanthine, theophylline, and harmine) and 4 metabolites with decreased abundance (e.g., trigonelline) in both the plasma and urine of the HFD-fed dogs were identified. In conclusion, the metabolomic analysis revealed molecular events underlying a canine HFD model and identified several metabolites as potential targets for the prevention and treatment of obesity-related metabolic disorders.

The Role of the Intestinal Microbiota in Nonalcoholic Steatohepatitis

Nonalcoholic steatohepatitis (NASH) is a serious disease threatening public health, and its pathogenesis remains largely unclear. Recent scientific research has shown that intestinal microbiota and its metabolites have an important impact on the development of NASH. A balanced intestinal microbiota contributes to the maintenance of liver homeostasis, but when the intestinal microbiota is disequilibrated, it serves as a source of pathogens and molecules that lead to NASH. In this review, we mainly emphasize the key mechanisms by which the intestinal microbiota and its metabolites affect NASH. In addition, recent clinical trials and animal studies on the treatment of NASH by regulating the intestinal microbiota through prebiotics, probiotics, synbiotics and FMT have also been briefly elaborated. With the increasing understanding of interactions between the intestinal microbiota and liver, accurate and personalized detection and treatment methods for NASH are expected to be established.

High Remnant Cholesterol Level Potentiates the Development of Hypertension

BACKGROUND

Emerging evidence suggests an association between remnant cholesterol (RC) and vascular damage and hypertension. However, this association has not been explored in a large-scale population in China, and a temporal relationship between RC and hypertension also needs to be investigated.

METHODS

We conducted a retrospective cross-sectional study in 2,199,366 individuals and a longitudinal study in 24,252 individuals with repeated measurements of lipid profile and blood pressure in at least a 3-year follow-up. The logistic model was used to explore the association between lipid components and hypertension in the cross-sectional analysis. The Cox model was used to analyze the association between high RC (HRC) at baseline and the subsequent incidence of hypertension or the association between hypertension at baseline and incidence of HRC. The cross-lagged panel model was applied to analyze the temporal relationship between RC and hypertension.

RESULTS

RC level as a continuous variable had the highest correlation with hypertension among lipid profiles, including RC, low-density lipoprotein cholesterol, total cholesterol, non-high-density lipoprotein cholesterol, and triglycerides, with an odds ratio of 1.59 (95% confidence interval: 1.58-1.59). In the longitudinal cohort, HRC at baseline was associated with incident hypertension. We further explored the temporal relationship between RC and hypertension using the cross-lagged analysis, and the results showed that RC increase preceded the development of hypertension, rather than vice versa.

CONCLUSIONS

RC had an unexpected high correlation with the prevalence and incidence of hypertension. Moreover, RC increase might precede the development of hypertension, suggesting the potential role of RC in the development of hypertension.

Liver Fibrosis and MAFLD: From Molecular Aspects to Novel Pharmacological Strategies

Metabolic-associated fatty liver disease (MAFLD) is a new disease definition, and this nomenclature MAFLD was proposed to renovate its former name, non-alcoholic fatty liver disease (NAFLD). MAFLD/NAFLD have shared and predominate causes from nutrition overload to persistent liver damage and eventually lead to the development of liver fibrosis and cirrhosis. Unfortunately, there is an absence of effective treatments to reverse MAFLD/NAFLD-associated fibrosis. Due to the significant burden of MAFLD/NAFLD and its complications, there are active investigations on the development of novel targets and pharmacotherapeutics for treating this disease. In this review, we cover recent discoveries in new targets and molecules for antifibrotic treatment, which target pathways intertwined with the fibrogenesis process, including lipid metabolism, inflammation, cell apoptosis, oxidative stress, and extracellular matrix formation. Although marked advances have been made in the development of antifibrotic therapeutics, none of the treatments have achieved the endpoints evaluated by liver biopsy or without significant side effects in a large-scale trial. In addition to the discovery of new druggable targets and pharmacotherapeutics, personalized medication, and combinatorial therapies targeting multiple profibrotic pathways could be promising in achieving successful antifibrotic interventions in patients with MAFLD/NAFLD.

NAFLD as a continuous driver in the whole spectrum of vascular disease

Vascular disease is the prime determinant to cardiovascular morbidities and mortalities, which comprises the early vascular damage and subsequent cardiovascular events. Non-alcohol Fatty Liver Disease (NAFLD) is a systemic metabolic disorder that drives the progression of vascular disease through complex interactions. Although a causal relationship between NAFLD and cardiovascular disease (CVD) has not been established, a growing number of epidemiological studies have demonstrated an independent association between NAFLD and early vascular disease and subsequent cardiovascular events. In addition, mechanistic studies suggest that NAFLD initiates and accelerates vascular injury by increasing systemic inflammation and oxidative stress, impairing insulin sensitivity and lipid metabolism, and modulating epigenetics, the intestinal flora and hepatic autonomic nervous system; thus, NAFLD is a putative driving force for CVD progression. In this review, we summarize the clinical evidence supporting the association of NAFLD with subclinical vascular disease and cardiovascular events and discuss the potential mechanisms by which NAFLD promotes the progression of vascular disease.

Hepatocyte SH3RF2 Deficiency Is a Key Aggravator for NAFLD

BACKGROUND AND AIMS

NAFLD has become the most common liver disease worldwide but lacks a well-established pharmacological therapy. Here, we aimed to investigate the role of an E3 ligase SH3 domain-containing ring finger 2 (SH3RF2) in NAFLD and to further explore the underlying mechanisms.

METHODS AND RESULTS

In this study, we found that SH3RF2 was suppressed in the setting of NAFLD across mice, monkeys, and clinical individuals. Based on a genetic interruption model, we further demonstrated that hepatocyte SH3RF2 deficiency markedly deteriorates lipid accumulation in cultured hepatocytes and diet-induced NAFLD mice. Mechanistically, SH3RF2 directly binds to ATP citrate lyase, the primary enzyme promoting cytosolic acetyl-coenzyme A production, and promotes its K48-linked ubiquitination-dependent degradation. Consistently, acetyl-coenzyme A was significantly accumulated in Sh3rf2-knockout hepatocytes and livers compared with wild-type controls, leading to enhanced de novo lipogenesis, cholesterol production, and resultant lipid deposition.

CONCLUSION

SH3RF2 depletion in hepatocytes is a critical aggravator for NAFLD progression and therefore represents a promising therapeutic target for related liver diseases.

A kinome screen reveals that Nemo-like kinase is a key suppressor of hepatic gluconeogenesis

Antihyperglycemic therapy is an important priority for the treatment of type 2 diabetes (T2D). Excessive hepatic glucose production (HGP) is a major cause of fasting hyperglycemia. Therefore, a better understanding of its regulation would be important to develop effective antihyperglycemic therapies. Using a gluconeogenesis-targeted kinome screening approach combined with transcriptome analyses, we uncovered Nemo-like kinase (NLK) as a potent suppressor of HGP. Mechanistically, NLK phosphorylates and promotes nuclear export of CRTC2 and FOXO1, two key regulators of hepatic gluconeogenesis, resulting in the proteasome-dependent degradation of the former and the inhibition of the self-transcriptional activity and expression of the latter. Importantly, the expression of NLK is downregulated in the liver of individuals with diabetes and in diabetic rodent models and restoring NLK expression in the mouse model ameliorates hyperglycemia. Therefore, our findings uncover NLK as a critical player in the gluconeogenic regulatory network and as a potential therapeutic target for T2D.

Metformin Is Associated with Higher Incidence of Acidosis, but Not Mortality, in Individuals with COVID-19 and Pre-existing Type 2 Diabetes

The safety and efficacy of anti-diabetic drugs are critical for maximizing the beneficial impacts of well-controlled blood glucose on the prognosis of individuals with COVID-19 and pre-existing type 2 diabetes (T2D). Metformin is the most commonly prescribed first-line medication for T2D, but its impact on the outcomes of individuals with COVID-19 and T2D remains to be clarified. Our current retrospective study in a cohort of 1,213 hospitalized individuals with COVID-19 and pre-existing T2D indicated that metformin use was significantly associated with a higher incidence of acidosis, particularly in cases with severe COVID-19, but not with 28-day COVID-19-related mortality. Furthermore, metformin use was significantly associated with reduced heart failure and inflammation. Our findings provide clinical evidence in support of continuing metformin treatment in individuals with COVID-19 and pre-existing T2D, but acidosis and kidney function should be carefully monitored in individuals with severe COVID-19.

CARD3 Promotes Cerebral Ischemia-Reperfusion Injury Via Activation of TAK1

Background Although multiple signaling cascades and molecules contributing to the pathophysiological process have been studied, the treatments for stroke against present targets have not acquired significant clinical progress. Although CARD3 (caspase activation and recruitment domain 3) protein is an important factor involved in regulating immunity, inflammation, lipid metabolism, and apoptosis, its role in cerebral stroke is currently unknown. Methods and Results Using a mouse model of ischemia-reperfusion (I-R) injury based on transient blockage of the middle cerebral artery, we have found that CARD3 expression is upregulated in a time-dependent manner during I-R injury. Further animal study revealed that, relative to control mice, CARD3-knockout mice exhibited decreased inflammatory response and neuronal apoptosis, with reduced infarct volume and lower neuropathological scores. In contrast, neuron-specific CARD3-overexpressing transgenic (CARD3-TG) mice exhibited increased I-R induced injury compared with controls. Mechanistically, we also found that the activation of TAK1 (transforming growth factor-β-activated kinase 1) was enhanced in CARD3-TG mice. Furthermore, the increased inflammation and apoptosis seen in injured CARD3-TG brains were reversed by intravenous administration of the TAK1 inhibitor 5Z-7-oxozeaenol. Conclusions These results indicate that CARD3 promotes I-R injury via activation of TAK1, which not only reveals a novel regulatory axis of I-R induced brain injury but also provides a new potential therapeutic approach for I-R injury.

TNFAIP3 Interacting Protein 3 Overexpression Suppresses Nonalcoholic Steatohepatitis by Blocking TAK1 Activation

Nonalcoholic steatohepatitis (NASH) is an unmet clinical challenge due to the rapid increase in its occurrence but the lack of approved drugs to treat it. Further unraveling of the molecular mechanisms underlying NASH may identify potential successful drug targets for this condition. Here, we identified TNFAIP3 interacting protein 3 (TNIP3) as a novel inhibitor of NASH. Hepatocyte-specific TNIP3 transgenic overexpression attenuates NASH in two dietary models in mice. Mechanistically, this inhibitory effect of TNIP3 is independent of its conventional role as an inhibitor of TNFAIP3. Rather, TNIP3 directly interacts with TAK1 and inhibits its ubiquitination and activation by the E3 ligase TRIM8 in hepatocytes in response to metabolic stress. Notably, adenovirus-mediated TNIP3 expression in the liver substantially blocks NASH progression in mice. These results suggest that TNIP3 may be a promising therapeutic target for NASH management.

Tumor Progression Locus 2 in Hepatocytes Potentiates Both Liver and Systemic Metabolic Disorders in Mice

Tumor progression locus 2 (TPL2), a serine/threonine kinase, has been regarded as a potentially interesting target for the treatment of various diseases with an inflammatory component. However, the function of TPL2 in regulating hepatocyte metabolism and liver inflammation during the progression of nonalcoholic fatty liver disease (NAFLD) is poorly understood. Here, we report that TPL2 protein expression was significantly increased in fatty liver from diverse species, including humans, monkeys, and mice. Further investigations revealed that compared to wild-type (WT) littermates, hepatocyte-specific TPL2 knockout (HKO) mice exhibited improved lipid and glucose imbalance, reserved insulin sensitivity, and alleviated inflammation in response to high-fat diet (HFD) feeding. Overexpression of TPL2 in hepatocytes led to the opposite phenotype. Regarding the mechanism, we found that mitogen-activated protein kinase kinase 7 (MKK7) was the specific substrate of TPL2 for c-Jun N-terminal kinase (JNK) activation. TPL2-MKK7-JNK signaling in hepatocytes represents a promising drugable target for treating NAFLD and associated metabolic disorders. Conclusion: In hepatocytes, TPL2 acts as a key mediator that promotes both liver and systemic metabolic disturbances by specifically increasing MKK7-JNK activation.

Carboxyl-Terminal Modulator Protein Ameliorates Pathological Cardiac Hypertrophy by Suppressing the Protein Kinase B Signaling Pathway

Background

Carboxyl‐terminal modulator protein (CTMP) has been implicated in cancer, brain injury, and obesity. However, the role of CTMP in pathological cardiac hypertrophy has not been identified.

Methods and Results

In this study, decreased expression of CTMP was observed in both human failing hearts and murine hypertrophied hearts. To further explore the potential involvement of CTMP in pathological cardiac hypertrophy, cardiac‐specific CTMP knockout and overexpression mice were generated. In vivo experiments revealed that CTMP deficiency exacerbated the cardiac hypertrophy, fibrosis, and function induced by pressure overload, whereas CTMP overexpression alleviated the response to hypertrophic stimuli. Consistent with the in vivo results, adenovirus‐mediated gain‐of‐function or loss‐of‐function experiments showed that CTMP also exerted a protective effect against hypertrophic responses to angiotensin II in vitro. Mechanistically, CTMP ameliorated pathological cardiac hypertrophy through the blockade of the protein kinase B signaling pathway. Moreover, inhibition of protein kinase B activation with LY294002 rescued the deteriorated effect in aortic banding–treated cardiac‐specific CTMP knockout mice.

Conclusions

Taken together, these findings imply, for the first time, that increasing the cardiac expression of CTMP may be a novel therapeutic strategy for pathological cardiac hypertrophy.

Hepatocyte DUSP14 maintains metabolic homeostasis and suppresses inflammation in the liver

Nonalcoholic fatty liver disease (NAFLD) is a prevalent and complex disease that confers a high risk of severe liver disorders. Despite such public and clinical health importance, very few effective therapies are currently available for NAFLD. We report a protective function and the underlying mechanism of dual-specificity phosphatase 14 (DUSP14) in NAFLD and related metabolic disorders. Insulin resistance, hepatic lipid accumulation, and concomitant inflammatory responses, key pathological processes involved in NAFLD development, were significantly ameliorated by hepatocyte-specific DUSP14 overexpression (DUSP14-HTG) in high-fat diet (HFD)-induced or genetically obese mouse models. By contrast, specific DUSP14 deficiency in hepatocytes (DUSP14-HKO) aggravated these pathological alterations. We provided mechanistic evidence that DUSP14 directly binds to and dephosphorylates transforming growth factor β-activated kinase 1 (TAK1), resulting in the reduced activation of TAK1 and its downstream signaling molecules c-Jun N-terminal kinase 1 (JNK), p38, and nuclear factor kappa B NF-κB. This effect was further evidenced by the finding that inhibiting TAK1 activity effectively attenuated the deterioration of glucolipid metabolic phenotype in DUSP14-HKO mice challenged by HFD administration. Furthermore, we identified that both the binding domain and the phosphatase activity of DUSP14 are required for its protective role against hepatic steatosis, because interruption of the DUSP14-TAK1 interaction abolished the mitigative effects of DUSP14.

CONCLUSION

Hepatocyte DUSP14 is required for maintaining hepatic metabolic homeostasis and for suppressing inflammation, a novel function that relies on constraining TAK1 hyperactivation. (Hepatology 2018;67:1320-1338).

Reduced atherosclerosis lesion size, inflammatory response in miR-150 knockout mice via macrophage effects

Atherosclerosis is considered to be a chronic inflammatory disease that can lead to severe clinically important cardiovascular events. miR-150 is a small noncoding RNA that significantly enhances inflammatory responses by upregulating endothelial cell proliferation and migration, as well as intravascular environmental homeostasis. However, the exact role of miR-150 in atherosclerosis remains unknown. Here, we investigated the effect of miR-150 deficiency on atherosclerosis development. Using double-knockout (miR-150^-/- and ApoE^-/-) mice, we measured atherosclerotic lesion size and stability. Meanwhile, we conducted in vivo bone marrow transplantation to identify cellular-level components of the inflammatory response. Compared with mice deficient only in ApoE, the double-knockout mice had significantly smaller atherosclerotic lesions and displayed an attenuated inflammatory response. Moreover, miR-150 ablation promoted plaque stabilization via increases in smooth muscle cell and collagen content and decreased macrophage infiltration and lipid accumulation. The in vitro experiments indicated that an inflammatory response with miR-150 deficiency in atherosclerosis results directly from upregulated expression of the cytoskeletal protein, PDZ and LIM domain 1 (PDLIM1), in macrophages. More importantly, the decreases in phosphorylated p65 expression and inflammatory cytokine secretion induced by miR-150 ablation were reversed by PDLIM1 knockdown. These findings suggest that miR-150 is a promising target for the management of atherosclerosis.

The deubiquitinating enzyme TNFAIP3 mediates inactivation of hepatic ASK1 and ameliorates nonalcoholic steatohepatitis

Activation of apoptosis signal-regulating kinase 1 (ASK1) in hepatocytes is a key process in the progression of nonalcoholic steatohepatitis (NASH) and a promising target for treatment of the condition. However, the mechanism underlying ASK1 activation is still unclear, and thus the endogenous regulators of this kinase remain open to be exploited as potential therapeutic targets. In screening for proteins that interact with ASK1 in the context of NASH, we identified the deubiquitinase tumor necrosis factor alpha-induced protein 3 (TNFAIP3) as a key endogenous suppressor of ASK1 activation, and we found that TNFAIP3 directly interacts with and deubiquitinates ASK1 in hepatocytes. Hepatocyte-specific ablation of Tnfaip3 exacerbated nonalcoholic fatty liver disease- and NASH-related phenotypes in mice, including glucose metabolism disorders, lipid accumulation and enhanced inflammation, in an ASK1-dependent manner. In contrast, transgenic or adeno-associated virus-mediated TNFAIP3 gene delivery in the liver in both mouse and nonhuman primate models of NASH substantially blocked the onset and progression of the disease. These results implicate TNFAIP3 as a functionally important endogenous suppressor of ASK1 hyperactivation in the pathogenesis of NASH and identify it as a potential new molecular target for NASH therapy.