Multicombination Approach Suppresses Listeria monocytogenes-Induced Septicemia-Associated Acute Hepatic Failure: The Role of iRhom2 Signaling

Fisetin is a selective adenosine triphosphate-competitive inhibitor for mitogen-activated protein kinase kinase 4 to inhibit lipopolysaccharide-stimulated inflammation

The mitogen-activated protein kinase kinase 4 (MKK4), a member of the MAP kinase kinase family, directly phosphorylates and activates the c-Jun NH2-terminal kinases (JNK), in response to proinflammatory cytokines and cellular stresses. Regulation of the MKK4 activity is considered to be a novel approach for the prevention and treatment of inflammation. The aim of this study was to identify whether fisetin, a potential anti-inflammatory compound, targets MKK4-JNK cascade to inhibit lipopolysaccharide (LPS)-stimulated inflammatory response. RAW264 macrophage pretreated with fisetin following LPS stimulation was used as a cell model to investigate the transactivation and expression of related-inflammatory genes by transient transfection assay, electrophoretic mobility shift assay (EMSA), or enzyme-linked immunosorbent assay (ELISA), and cellular signaling as well as binding of related-signal proteins by Western blot, pull-down assay and kinase assay, and molecular modeling. The transactivation and expression of cyclooxygenase-2 (COX-2) gene as well as prostaglandin E2 (PGE2) secretion induced by LPS were inhibited by fisetin in a dose-dependent manner. Signaling transduction analysis demonstrated that fisetin selectively inhibited MKK4-JNK1/2 signaling to suppress the phosphorylation of transcription factor AP-1 without affecting the NF-κB and Jak2-Stat3 signaling as well as the phosphorylation of Src, Syk, and TAK1. Furthermore, in vitro and ex vivo pull-down assay using cell lysate or purified protein demonstrated that fisetin could bind directly to MKK4. Molecular modeling using the Molecular Operating Environment™ software indicated that fisetin docked into the ATP-binding pocket of MKK4 with a binding energy of -71.75 kcal/mol and formed a 1.70 Å hydrogen bound with Asp247 residue of MKK4. The IC50 of fisetin against MKK4 was estimated as 2.899 μM in the kinase assay, and the ATP-competitive effect was confirmed by ATP titration. Taken together, our data revealed that fisetin is a potent selective ATP-competitive MKK4 inhibitor to suppress MKK4-JNK1/2-AP-1 cascade for inhibiting LPS-induced inflammation.

Deficiency in Inactive Rhomboid Protein2 (iRhom2) Alleviates Alcoholic Liver Fibrosis by Suppressing Inflammation and Oxidative Stress

Chronic alcohol exposure can lead to liver pathology relating to inflammation and oxidative stress, which are two of the major factors in the incidence of liver fibrosis and even liver cancer. The underlying molecular mechanisms regarding hepatic lesions associated with alcohol are not fully understood. Considering that the recently identified iRhom2 is a key pathogenic mediator of inflammation, we performed in vitro and in vivo experiments to explore its regulatory role in alcohol-induced liver fibrosis. We found that iRhom2 knockout significantly inhibited alcohol-induced inflammatory responses in vitro, including elevated expressions of inflammatory cytokines (IL-1β, IL-6, IL-18, and TNF-α) and genes associated with inflammatory signaling pathways, such as TACE (tumor necrosis factor-alpha converting enzyme), TNFR1 (tumor necrosis factor receptor 1), and TNFR2, as well as the activation of NF-κB. The in vivo results confirmed that long-term alcohol exposure leads to hepatocyte damage and fibrous accumulation. In this pathological process, the expression of iRhom2 is promoted to activate the TACE/NF-κB signaling pathway, leading to inflammatory responses. Furthermore, the deletion of iRhom2 blocks the TACE/NF-κB signaling pathway and reduces liver damage and fibrosis caused by alcohol. Additionally, the activation of the JNK/Nrf2/HO-1 signaling pathway caused by alcohol exposure was also noted in vitro and in vivo. In the same way, knockout or deleting iRhom2 blocked the JNK/Nrf2/HO-1 signaling pathway to regulate the oxidative stress. Therefore, we contend that iRhom2 is a key regulator that promotes inflammatory responses and regulates oxidative stress in alcoholic liver fibrosis lesions. We posit that iRhom2 is potentially a new therapeutic target for alcoholic liver fibrosis.

Juglanin protects against high fat diet-induced renal injury by suppressing inflammation and dyslipidemia via regulating NF-κB/HDAC3 signaling

Obesity is an important factor implicated in chronic kidney disease (CKD). Juglanin (Jug) is a natural compound extracted from the crude Polygonumaviculare, showing anti-inflammatory and anti-diabetic effects. However, whether Jug has protective effects against obesity-induced renal injury, little has been investigated. Herein, we attempted to explore the potential of Jug in mediating obesity-induced kidney disease in high fat diet (HFD)-challenged mice. Our results suggested that chronic HFD feeding markedly increased the body weights of mice compared to the ones fed with normal chow diet (NCD), along with significant glucose intolerance and insulin resistance. However, these metabolic disorders induced by HFD were effectively alleviated by Jug treatments in a dose-dependent manner. Moreover, HFD-challenged mice showed apparent histopathological changes in renal tissues with significant collagen accumulation, which were attenuated by Jug supplementation. In addition, Jug treatment decreased the expression levels of kidney injury molecule-1 (KIM-1), while increased nephrin and podocin expression levels in kidney of HFD-challenged mice, improving the renal dysfunction. Furthermore, HFD led to lipid deposition in kidney samples of mice by enhancing abnormal lipid metabolism. In addition, HFD promoted the releases of circulating pro-inflammatory cytokines, and enhanced the renal inflammation by activating nuclear factor-kappa B/histone deacetylase 3 (NF-κB/HDAC3) signaling. HFD-induced dyslipidemia and inflammation were considerably abrogated by Jug administration in mice. The protective effects of Jug against renal injury were confirmed in palmitate (PA)-stimulated HK2 cells in vitro mainly through suppressing the nuclear translocation of NF-κB and HDAC3, repressing inflammation and lipid accumulation eventually. Hence, Jug could ameliorate HFD-induced kidney injury mainly through blocking the NF-κB/HDAC3 nuclear translocation.

Carminic acid supplementation protects against fructose-induced kidney injury mainly through suppressing inflammation and oxidative stress via improving Nrf-2 signaling

Excessive fructose (Fru) intake has become an increased risk for chronic kidney disease progression. Despite extensive researches that have been performed to develop effective treatments against Fru-induced renal injury, the outcome has achieved limited success. In this study, we attempted to explore whether carminic acid (CA) could influence the progression of Fru-induced kidney injury, and the underlying molecular mechanism. At first, our in vitro results showed that CA significantly reduced inflammation in mouse tubular epithelial cells and human tubule epithelial cells stimulated by Fru. The anti-inflammatory effects of CA were associated with the blockage of nuclear factor-κB (NF-κB) signaling. In addition, Fru-exposed cells showed higher oxidative stress, which was effectively restrained by CA treatment through improving nuclear factor (erythroid-derived 2)-like 2 (Nrf-2) nuclear translocation. Importantly, we found that Fru-induced inflammation and oxidative stress were accelerated in cells with Nrf-2 knockdown. What's more, in Fru-stimulated cells, CA-alleviated inflammatory response and reactive oxygen species (ROS) production were evidently abolished by Nrf-2 knockdown. The in vivo analysis demonstrated that Fru led to metabolic disorder, excessive albuminuria and histologic changes in renal tissues, which were effectively reversed by CA supplementation. We confirmed that CA significantly reduced inflammation and oxidative stress in the kidneys of mice through regulating NF-κB and Nrf-2 signaling pathways, eventually alleviating the progression of chronic kidney injury. Taken together, these results identified CA as a potential therapeutic strategy for metabolic stress-induced renal injury through restraining inflammation and oxidative stress via the improvement of Nrf-2 signaling.

iRhom2 Promotes Hepatic Steatosis by Activating MAP3K7-Dependent Pathway

BACKGROUND AND AIMS

Nonalcoholic fatty liver disease (NAFLD) has been widely recognized as a precursor to metabolic complications. Elevated inflammation levels are predictive of NAFLD-associated metabolic disorder. Inactive rhomboid-like protein 2 (iRhom2) is regarded as a key regulator in inflammation. However, the precise mechanisms by which iRhom2-regulated inflammation promotes NAFLD progression remain to be elucidated.

APPROACH AND RESULTS

Here, we report that insulin resistance, hepatic steatosis, and specific macrophage inflammatory activation are significantly alleviated in iRhom2-deficient (knockout [KO]) mice, but aggravated in iRhom2 overexpressing mice. We further show that, mechanistically, in response to a high-fat diet (HFD), iRhom2 KO mice and mice with iRhom2 deficiency in myeloid cells only showed less severe hepatic steatosis and insulin resistance than controls. Inversely, transplantation of bone marrow cells from healthy mice to iRhom2 KO mice expedited the severity of insulin resistance and hepatic dyslipidemia. Of note, in response to HFD, hepatic iRhom2 binds to mitogen-activated protein kinase kinase kinase 7 (MAP3K7) to facilitate MAP3K7 phosphorylation and nuclear factor kappa B cascade activation, thereby promoting the activation of c-Jun N-terminal kinase/insulin receptor substrate 1 signaling, but disturbing AKT/glycogen synthase kinase 3β-associated insulin signaling. The iRhom2/MAP3K7 axis is essential for iRhom2-regulated liver steatosis.

CONCLUSIONS

iRhom2 may represent a therapeutic target for the treatment of HFD-induced hepatic steatosis and insulin resistance.

Nanotechnology for Hepatocellular Carcinoma: From Surveillance, Diagnosis to Management

Hepatocellular carcinoma (HCC) remains the fourth leading cause of cancer-related death worldwide. However, the clinical diagnosis and treatment modalities are still relatively limited, which urgently require the development of new effective technologies. Recently, nanotechnology has gained extensive attention in HCC surveillance, imaging and pathological diagnosis, and therapeutic strategies. Typically, nanomedicines have been focused on early HCC diagnosis and precise treatment of advanced HCC, which has developed and improved a variety of new technologies and agents for future clinical practice. Furthermore, strategies of facilitating drug release and delivery in current treatment processes such as ablation, systematic therapy, transcatheter arterial chemoembolization, molecular targeted therapy, and immune-modulating therapy have also been studied widely. This review summarizes the recent advances in this area according to current clinical HCC guidelines: 1) Nanoparticle-based HCC surveillance; 2) Nanotechnology for HCC diagnosis; 3) Therapeutic advances for HCC Management; 4) Limitations of applications in nanotechnology for HCC; 5) Conclusions and perspectives. Although there are still many limitations and difficulties to overcome, the investigations of nanomedicines are believed to show potential applications in clinical practice.

Applications of Nanobiomaterials in the Therapy and Imaging of Acute Liver Failure

This review focuses on the therapeutic mechanisms, targeting strategies of various nanomaterials in acute liver failure, and recent advances of diverse nanomaterials for acute liver failure therapy, diagnosis, and imaging. This review provides an outlook on the applications of nanomaterials, especially on the new horizons in acute liver failure therapy, and inspires broader interests across various disciplines. Acute liver failure (ALF), a fatal clinical disease featured with overwhelming hepatocyte necrosis, is a grand challenge in global health. However, a satisfactory therapeutic option for curing ALF is still absent, other than liver transplantation. Nanobiomaterials are currently being developed for the diagnosis and treatment of ALF. The liver can sequester most of nanoparticles from blood circulation, which becomes an intrinsic superiority for nanobiomaterials targeting hepatic diseases. Nanobiomaterials can enhance the bioavailability of free drugs, thereby significantly improving the therapeutic effects in ALF. Nanobiomaterials can also increase the liver accumulation of therapeutic agents and enable more effective targeting of the liver or specific liver cells. In addition, stimuli-responsive, optical, or magnetic nanomaterials exhibit great potential in the therapeutical, diagnostic, and imaging applications in ALF. Therefore, therapeutic agents in combination with nanobiomaterials increase the specificity of ALF therapy, diminish adverse systemic effects, and offer a multifunctional theranostic platform. Nanobiomaterial holds excellent significance and prospects in ALF theranostics. In this review, we summarize the therapeutic mechanisms and targeting strategies of various nanobiomaterials in ALF. We highlight recent developments of diverse nanomedicines for ALF therapy, diagnosis, and imaging. Furthermore, the challenges and future perspectives in the theranostics of ALF are also discussed.

Kupffer cell inactivation ameliorates immune liver injury via TNF-α/TNFR1 signal pathway in trichloroethylene sensitized mice

METHODS

36 female BALB/c mice were selected and randomly divided the mice into four groups. We established a BALB/c mouse model of TCE sensitization and pretreatment with GdCl3 (40 mg/kg) by intraperitoneal injection during the during the 17th and 19th days.

RESULTS

We found F4/80, the marker of Kupffer cell, was increased in TCE positive group. GdCl3 treatment successfully blocked the activation of Kupffer cell. TNF-α was increased significantly in liver of TCE sensitized mice and decreased significantly when low-dose GdCl3 was used. We found TNF receptor 1 (TNFR1) was increased significantly and GdCl3 treatment resumed the expression of TNFR1 to normal level, as well as the F4/80, TNF-α and TNFR1 mRNA. We also found both caspase-8 and caspase-3 increased in TCE positive group and decreased in TCE + GdCl3 positive group. The number of apoptotic cells in TCE sensitized mice increased by TUNEL staining, and GdCl3 treatment alleviated this increase. Some cells showed edema and inflammatory cell aggregation in liver of TCE positive group, while in the TCE + GdCl3 positive group, the cytoplasm became loose and vacuole-like degeneration occurred.

CONCLUSION

Our study unveils cross-talk between Kupffer cell activation and TNFR1 which mediate apoptosis in liver of TCE sensitized mice.

Functional loss of inactive rhomboid-like protein 2 mitigates obesity by suppressing pro-inflammatory macrophage activation-triggered adipose inflammation

Objective

Chronic inflammation of adipose tissues contributes to obesity-triggered insulin resistance. Unfortunately, the potential molecular mechanisms regarding obesity-associated systemic inflammation and metabolic disorder remain complicated. Here, we report that inactive rhomboid-like protein 2 (iRhom2) was increased in overweight mice with adipose inflammation.

Methods

Mice with deletion of iRhom2 on a C57BL/6J background, mice without deletion of this gene (controls), and mice with deficiency of iRhom2 only in myeloid cells were fed a standard chow diet (SCD) or a high-fat diet (HFD; 60% fat calories). Then the adipose tissues or bone marrow cells were isolated for the further detection.

Results

After 16 weeks on a high-fat diet (HFD), obesity, chronic inflammation in adipose tissues, and insulin resistance were markedly mitigated in iRhom2 knockout (iRhom2 KO) mice, whereas these parameters were exaggerated in iRhom2 overactivated mice. The adverse influences of iRhom2 on adipose inflammation and associated pathologies were determined in db/db mice. We further demonstrated that, in response to an HFD, iRhom2 KO mice and mice with deletion only in the myeloid cells showed less severe adipose inflammation and insulin resistance than control groups. Conversely, transplantation of bone marrow cells from normal mice to iRhom2 KO mice unleashed severe systemic inflammation and metabolic dysfunction after HFD ingestion.

Conclusion

We identified iRhom2 as a key regulator that promotes obesity-associated metabolic disorders. Loss of iRhom2 from macrophages in adipose tissues may indirectly restrain inflammation and insulin resistance via blocking crosslinks between macrophages and adipocytes. Hence, iRhom2 may be a therapeutic target for obesity-induced metabolic dysfunction.

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iRhom2 deletion protects against high fat diet-induced obesity.

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Alteration of iRhom2 activity is coupled with high fat diet-triggered adipose inflammation.

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Myeloid cell-specific iRhom2 knockout reduces high fat diet-induced adipose inflammation and dyslipidemia.

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iRhom2 expression only in myeloid cells increases high fat diet-induced adipose inflammation and dyslipidemia.

Endoplasmic reticulum stress-induced iRhom2 up-regulation promotes macrophage-regulated cardiac inflammation and lipid deposition in high fat diet (HFD)-challenged mice: Intervention of fisetin and metformin

Endoplasmic reticulum stress (ERS) has been implicated in obesity-associated cardiac remodeling and dysfunction. Inactive rhomboid protein 2 (iRhom2), also known as Rhbdf2, is an inactive member of the rhomboid intramembrane proteinase family, playing an essential role in regulating inflammation. Nevertheless, the role of ERS-meditated iRhom2 pathway in metabolic stress-induced cardiomyopathy remains unknown. In the study, we showed that 4-PBA, as an essential ERS inhibitor, significantly alleviated high fat diet (HFD)-induced metabolic disorder and cardiac dysfunction in mice. Additionally, lipid deposition in heart tissues was prevented by 4-PBA in HFD-challenged mice. Moreover, 4-PBA blunted the expression of iRhom2, TACE, TNFR2 and phosphorylated NF-κB to prevent HFD-induced expression of inflammatory factors. Further, 4-PBA restrained HFD-triggered oxidative stress by promoting Nrf-2 signaling. Importantly, 4-PBA markedly suppressed cardiac ERS in HFD mice. The anti-inflammation, anti-ERS and anti-oxidant effects of 4-PBA were verified in palmitate (PAL)-incubated macrophages and cardiomyocytes. In addition, promoting ERS could obviously enhance iRhom2 signaling in vitro. Intriguingly, our data demonstrated that PAL-induced iRhom2 up-regulation apparently promoted macrophage to generate inflammatory factors that could promote cardiomyocyte inflammation and lipid accumulation. Finally, interventions by adding fisetin or metformin significantly abrogated metabolic stress-induced cardiomyopathy through the mechanisms mentioned above. In conclusion, this study provided a novel mechanism for metabolic stress-induced cardiomyopathy pathogenesis. Therapeutic strategy to restrain ROS/ERS/iRhom2 signaling pathway could be developed to prevent myocardial inflammation and lipid deposition, consequently alleviating obesity-induced cardiomyopathy.

Activated TNF-α/RIPK3 signaling is involved in prolonged high fat diet-stimulated hepatic inflammation and lipid accumulation: inhibition by dietary fisetin intervention

Increasing evidence indicates that high-fat diet (HFD) is a predisposing factor for metabolic syndrome-associated systemic inflammation and nonalcoholic fatty liver disease (NAFLD).

Fisetin supplementation prevents high fat diet-induced diabetic nephropathy by repressing insulin resistance and RIP3-regulated inflammation

Obesity-related renal disease is related to caloric excess promoting deleterious cellular responses.

iRhom2 loss alleviates renal injury in long-term PM2.5-exposed mice by suppression of inflammation and oxidative stress

Particulate matter (PM2.5) is a risk factor for organ injury and disease progression, such as lung, brain and liver. However, its effects on renal injury and the underlying molecular mechanism have not been understood. The inactive rhomboid protein 2 (iRhom2), also known as rhomboid family member 2 (Rhbdf2), is a necessary modulator for shedding of tumor necrosis factor-α (TNF-α) in immune cells, and has been explored in the pathogenesis of chronic renal diseases. In the present study, we found that compared to the wild type (iRhom2^+/+) mice, iRhom2 knockout (iRhom2^-/-) protected PM_2.5-exposed mice from developing severe renal injury, accompanied with improved renal pathological changes and functions. iRhom2^-/- mice exhibited reduced inflammatory response, as evidenced by the reduction of interleukin 1β (IL-1β), IL-6, tumor necrosis factor-α (TNF-α) and IL-18 in kidney samples, which might be, at least partly, through inactivating TNF-α converting enzyme/TNF-α receptors (TACE/TNFRs) and inhibitor of α/nuclear factor κ B (IκBα/NF-κB) signaling pathways. In addition, oxidative stress was also restrained by iRhom2^-/- in kidney of PM_2.5-exposed mice by enhancing heme oxygenase/nuclear factor erythroid 2-related factor 2 (HO-1/Nrf-2) expressions, and reducing phosphorylated c-Jun N-terminal kinase (JNK). In vitro, blockage of HO-1 or Nrf-2 rescued the inflammatory response and oxidative stress that were reduced by iRhom2 knockdown in PM_2.5-incubated RAW264.7 cells. Similar results were observed in JNK activator-treated cells. Taken together, our findings indicated that iRhom2 played an essential role in regulating PM_2.5-induced chronic renal damage, thus revealing a potential target for preventing chronic kidney diseases development.

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Suppression of iRhom2 negatively regulates inflammatory response in mouse macrophages RAW264.7 cells.

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iRhom2 deficiency alleviates PM2.5-induced renal injury by reducing inflammatory infiltration.

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iRhom2 inhibition reduces oxidative stress and JNK activation in PM2.5-induced renal injury in vitro and in vivo.

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PM2.5-induced renal injury via iRhom2-regulated oxidative stress and inflammation.