TIMP3 overexpression in macrophages protects from insulin resistance, adipose inflammation, and nonalcoholic fatty liver disease in mice

Identifying MS4A6A+ macrophages as potential contributors to the pathogenesis of nonalcoholic fatty liver disease, periodontitis, and type 2 diabetes mellitus

Purpose

Concrete epidemiological evidence has suggested the mutually-contributing effect respectively between nonalcoholic fatty liver disease (NAFLD), type 2 diabetes mellitus (T2DM), and periodontitis (PD); however, their shared crosstalk mechanism remains an open issue.

Method

The NAFLD, PD, and T2DM-related datasets were obtained from the NCBI GEO repository. Their common differentially expressed genes (DEGs) were identified and the functional enrichment analysis performed by the DAVID platform determined relevant biological processes and pathways. Then, the STRING database established a PPI network of such DEGs and topological analysis through Cytoscape 3.7.1 software along with the machine-learning analysis by the least absolute shrinkage and selection operator (LASSO) algorithm screened out hub characteristic genes. Their efficacy was validated by external datasets using the receiver operating characteristic (ROC) curve, and gene expression and location of the most robust one was determined using single-cell sequencing and immunohistochemical staining. Finally, the promising drugs were predicted through the CTD database, and the CB-DOCK 2 and Pymol platform mimicked molecular docking.

Result

Intersection of differentially expressed genes from three datasets identified 25 shared DEGs of the three diseases, which were enriched in MHC II-mediated antigen presenting process. PPI network and LASSO machine-learning analysis determined 4 feature genes, of which the MS4A6A gene mainly expressed by macrophages was the hub gene and key immune cell type. Molecular docking simulation chosen fenretinide as the most promising medicant for MS4A6A+ macrophages.

Conclusion

MS4A6A+ macrophages were suggested to be important immune-related mediators in the progression of NAFLD, PD, and T2DM pathologies.

The Important Role of Phosphatidylserine, ADAM17, TNF-Alpha, and Soluble MER on Efferocytosis Activity in Central Obesity

Background

Obesity is expected to hinder efferocytosis due to ADAM17-mediated cleavage of the MER tyrosine kinase receptor, producing soluble MER (sMER) that disrupts MERTK binding to cell death markers. However, the intracellular efferocytosis pathway in central obesity remains elusive, particularly the role of low-grade chronic inflammation in its initiation and identification of binding signals that disrupt efferocytosis.

Objective

We investigate the efferocytosis signaling pathway in men with central obesity and its relationship with inflammation, cell death, and related processes.

Methods

A cross-sectional study was conducted, and clinical data and blood samples were collected from 56 men with central obesity (obese group) and 29 nonobese individuals (control group). Clinical evaluations and predefined biochemical screening tests were performed. The efferocytosis signaling pathway was investigated by measuring phosphatidylserine (PS), ADAM17, TNF-alpha (TNF-α), and sMER.

Results

Metabolic syndrome was detected in more than half of the participants in the obese group according to the predefined tests. Mean levels of PS, TNF-α, and sMER were higher in the obese group but not significantly different from those of the control group. Further analysis based on waist circumference (WC) ranges in the obese group revealed a significant increase in PS and sMER levels between the control group and the obese group with WC greater than 120 cm. ADAM17 levels were significantly higher in the obese group than in the control group. PS was positively correlated with WC and ADAM17. ADAM17 was positively correlated with TNF-α and sMER, indicating impaired efferocytosis.

Conclusions

Central obesity appeared to cause a disturbance in efferocytosis that began with cell damage and death, along with an enlargement of the WC and an ongoing inflammatory response. Efferocytosis was disrupted by proinflammatory cytokine regulators, which induced the production of sMER and interfered with the efferocytosis process.

TIMP3 overexpression in myeloid lineage alleviates pancreatic damage and confers resistance to the development of type 1 diabetes in the MLDS -induced model

Introduction

Type 1 diabetes mellitus (T1DM) development involves a complex interplay of genetic, environmental, and immunological factors. By modulating the activity of proteases and receptors, the protein tissue inhibitor of metalloproteinase 3 (TIMP3) plays a role in limiting the expression and function of pro-inflammatory cytokines, which have been implicated in the advancement of T1DM. This study was aimed at examining the effect of TIMP3 overexpression in myeloid cells on the development of T1DM.

Methods and results

Twelve weeks after multiple low doses of streptozotocin (MLDS) treatment, diabetic mice overexpressing TIMP3 specifically in myeloid cells under the CD68 promoter (MacT3 mice) showed improved insulin secretion, islet morphology and vascularization, antioxidant defense system, and regulatory factors of mitochondrial biosynthesis and function. To get mechanistic insights into the origin of this protection, the severity of insulitis and inflammatory parameters were evaluated in pancreatic tissues 11 days after MLSD treatment, showing significantly reduced insulitis and levels of the pro-inflammatory cytokine tumor necrosis factor-α, interleukin -1β, and interferon -γ in MacT3 mice.

Discussion

The results indicate that TIMP3 is involved in maintaining islet architecture and functions, at least in part, through modulation of pro-inflammatory cytokine production associated with insulitis and may represent a novel therapeutic strategy for T1DM.

The protease ADAM17 at the crossroads of disease: revisiting its significance in inflammation, cancer, and beyond

The protease A Disintegrin And Metalloproteinase 17 (ADAM17) plays a central role in the pathophysiology of several diseases. ADAM17 is involved in the cleavage and shedding of at least 80 known membrane-tethered proteins, which subsequently modulate several intracellular signaling pathways, and therefore alter cell behavior. Dysregulated expression and/or activation of ADAM17 has been linked to a wide range of autoimmune and inflammatory diseases, cancer, and cardiovascular disease. In this review, we provide an overview of the current state of knowledge from preclinical models and clinical data on the diverse pathophysiological roles of ADAM17, and discuss the mechanisms underlying ADAM17-mediated protein shedding and the potential therapeutic implications of targeting ADAM17 in these diseases.

TRAIL promotes the polarization of human macrophages toward a proinflammatory M1 phenotype and is associated with increased survival in cancer patients with high tumor macrophage content

Background

TNF-related apoptosis-inducing ligand (TRAIL) is a member of the TNF superfamily that can either induce cell death or activate survival pathways after binding to death receptors (DRs) DR4 or DR5. TRAIL is investigated as a therapeutic agent in clinical trials due to its selective toxicity to transformed cells. Macrophages can be polarized into pro-inflammatory/tumor-fighting M1 macrophages or anti-inflammatory/tumor-supportive M2 macrophages and an imbalance between M1 and M2 macrophages can promote diseases. Therefore, identifying modulators that regulate macrophage polarization is important to design effective macrophage-targeted immunotherapies. The impact of TRAIL on macrophage polarization is not known.

Methods

Primary human monocyte-derived macrophages were pre-treated with either TRAIL or with DR4 or DR5-specific ligands and then polarized into M1, M2a, or M2c phenotypes in vitro. The expression of M1 and M2 markers in macrophage subtypes was analyzed by RNA sequencing, qPCR, ELISA, and flow cytometry. Furthermore, the cytotoxicity of the macrophages against U937 AML tumor targets was assessed by flow cytometry. TCGA datasets were also analyzed to correlate TRAIL with M1/M2 markers, and the overall survival of cancer patients.

Results

TRAIL increased the expression of M1 markers at both mRNA and protein levels while decreasing the expression of M2 markers at the mRNA level in human macrophages. TRAIL also shifted M2 macrophages towards an M1 phenotype. Our data showed that both DR4 and DR5 death receptors play a role in macrophage polarization. Furthermore, TRAIL enhanced the cytotoxicity of macrophages against the AML cancer cells in vitro. Finally, TRAIL expression was positively correlated with increased expression of M1 markers in the tumors from ovarian and sarcoma cancer patients and longer overall survival in cases with high, but not low, tumor macrophage content.

Conclusions

TRAIL promotes the polarization of human macrophages toward a proinflammatory M1 phenotype via both DR4 and DR5. Our study defines TRAIL as a new regulator of macrophage polarization and suggests that targeting DRs can enhance the anti-tumorigenic response of macrophages in the tumor microenvironment by increasing M1 polarization.

Roles of Matrix Metalloproteinases and Their Natural Inhibitors in Metabolism: Insights into Health and Disease

Matrix metalloproteinases (MMPs) are a family of zinc-activated peptidases that can be classified into six major classes, including gelatinases, collagenases, stromelysins, matrilysins, membrane type metalloproteinases, and other unclassified MMPs. The activity of MMPs is regulated by natural inhibitors called tissue inhibitors of metalloproteinases (TIMPs). MMPs are involved in a wide range of biological processes, both in normal physiological conditions and pathological states. While some of these functions occur during development, others occur in postnatal life. Although the roles of several MMPs have been extensively studied in cancer and inflammation, their function in metabolism and metabolic diseases have only recently begun to be uncovered, particularly over the last two decades. This review aims to summarize the current knowledge regarding the metabolic roles of metalloproteinases in physiology, with a strong emphasis on adipose tissue homeostasis, and to highlight the consequences of impaired or exacerbated MMP actions in the development of metabolic disorders such as obesity, fatty liver disease, and type 2 diabetes.

Establishment of a gut-on-a-chip device with controllable oxygen gradients to study the contribution of Bifidobacterium bifidum to inflammatory bowel disease

Supplemental Bifidobacterium has been shown to aid in the prevention, alleviation, and treatment of inflammatory bowel disease (IBD), but the progression and mechanisms are largely unstudied, partly because of a lack of appropriate models. In vitro human gut models must accurately recreate oxygen concentration gradients consistent with those in vivo to mimic gene expression, metabolism, and host-microbiome interactions. A non-equipment-intensive and inexpensive method for constructing the gut-on-a-chip with physiological oxygen concentration gradients remains challenging. Here, we propose a simple strategy using numerical simulations in a dual-channel gut-on-a-chip to guide chip design and achieve controllable oxygen gradients. By varying the size of microchannels, blocking the oxygen penetration of the polydimethylsiloxane layer at a given location, and controlling the flow of hypoxic/aerobic media, this strategy creates steep gradients across the intestinal epithelium. IBD symptoms were induced on the chip by tumor necrosis factor-α and lipopolysaccharide treatment. Bifidobacterium bifidum has been validated to contribute to the stability of the intestinal epithelial barrier, including preventing epithelial barrier disruption and promoting the repair of damaged intestinal epithelial cell monolayers. These effects may be associated with the co-localization of Bifidobacterium bifidum and ZO-1. This simple but robust approach for designing microfluidic devices is applicable to various organs-on-chips in which fluid dynamics and concentration profiles between different media must be considered. With the customized chip, the integration of activated Bifidobacterium bifidum provides an initial step toward developing a multi-factorial IBD platform. The approach could be scaled up for disease modeling, high-throughput drug screening and personalized medicine.

The Effect of TGFβ1 in Adipocyte on Inflammatory and Fibrotic Markers at Different Stages of Adipocyte Differentiation

Transforming growth factor beta (TGFβ) is a versatile cytokine. Although a profibrotic role of TGFβ is well established, its effect on tissue inhibitor of metalloproteinase (TIMPs) and inflammatory mediators are incompletely described. This study investigates the profibrotic and pro-inflammatory role of TGFβ1 during adipocyte differentiation. NIH3T3L1 cells were used for the in vitro study and were differentiated by adding a standard differentiation mix either with rosiglitazone (R-Diff) or without (S-Diff). Recombinant TGFβ1 (2 ng/mL) was added to the undifferentiated preadipocyte during the commitment stage and at the terminal differentiation stage. TGFβ1 treatment significantly decreased adiponectin mRNA at both early commitment (>300 fold) and terminal differentiated cells [S-Diff (~33%) or R-Diff (~20%)]. TGFβ1 upregulated collagen VI mRNA and its regulators connective tissue growth factor (CCN2/CTGF), TIMP1 and TIMP3 mRNA levels in undifferentiated preadipocytes and adipocytes at commitment stage. But in the terminal differentiated adipocytes, changes in mRNA and protein of collagen VI and TIMP3 mRNA were not observed despite an increase in CCN2/CTGF, TIMP1 mRNA. Although TGFβ1 upregulated interleukin-6 (IL6) and monocyte chemoattractant protein-1 (MCP1) mRNA at all stages of differentiation, decreased tumor necrosis factor-α (TNFα) mRNA was observed early in adipocyte differentiation. This study highlights the complex role of TGFβ1 on extracellular matrix (ECM) remodeling and inflammatory markers in stimulating both synthetic and inhibitory markers of fibrosis at different stages of adipocyte differentiation.

Tissue Inhibitor of Metalloproteinase-3 Ameliorates Diabetes-Induced Retinal Inflammation

Purpose: Endogenous tissue inhibitor of matrix metalloproteinase-3 (TIMP-3) has powerful regulatory effects on inflammation and angiogenesis. In this study, we investigated the role of TIMP-3 in regulating inflammation in the diabetic retina.

Methods: Vitreous samples from patients with proliferative diabetic retinopathy (PDR) and non-diabetic patients were subjected to Western blot analysis. Streptozotocin-treated rats were used as a preclinical diabetic retinopathy (DR) model. Blood-retinal barrier (BRB) breakdown was assessed with fluorescein isothiocyanate (FITC)-conjugated dextran. Rat retinas, human retinal microvascular endothelial cells (HRMECs) and human retinal Müller glial cells were studied by Western blot analysis and ELISA. Adherence of human monocytes to HRMECs was assessed and in vitro angiogenesis assays were performed.

Results: Tissue inhibitor of matrix metalloproteinase-3 in vitreous samples was largely glycosylated. Intravitreal injection of TIMP-3 attenuated diabetes-induced BRB breakdown. This effect was associated with downregulation of diabetes-induced upregulation of the p65 subunit of NF-κB, intercellular adhesion molecule-1 (ICAM-1), and vascular endothelial growth factor (VEGF), whereas phospho-ERK1/2 levels were not altered. In Müller cell cultures, TIMP-3 significantly attenuated VEGF upregulation induced by high-glucose (HG), the hypoxia mimetic agent cobalt chloride (CoCl₂) and TNF-α and attenuated MCP-1 upregulation induced by CoCl₂ and TNF-α, but not by HG. TIMP-3 attenuated HG-induced upregulation of phospho-ERK1/2, caspase-3 and the mature form of ADAM17, but not the levels of the p65 subunit of NF-κB and the proform of ADAM17 in Müller cells. TIMP-3 significantly downregulated TNF-α-induced upregulation of ICAM-1 and VCAM-1 in HRMECs. Accordingly, TIMP-3 significantly decreased spontaneous and TNF-α- and VEGF-induced adherence of monocytes to HRMECs. Finally, TIMP-3 significantly attenuated VEGF-induced migration, chemotaxis and proliferation of HRMECs.

Conclusion:In vitro and in vivo data point to anti-inflammatory and anti-angiogenic effects of TIMP-3 and support further studies for its applications in the treatment of DR.

TIMP3 involvement and potentiality in the diagnosis, prognosis and treatment of diabetic nephropathy

Diabetic kidney disease, one of the most severe complications associated with diabetes, is characterized by albuminuria, glomerulosclerosis and progressive loss of renal function. Loss of TIMP3, an Extracellular matrix-bound protein, is a hallmark of diabetic nephropathy in human and mouse models, suggesting its pivotal role in renal diseases associated to diabetes. There is currently no specific therapy for diabetic nephropathy, and the ability to restore high TIMP3 activity specifically in the kidney may represent a potential therapeutic strategy for the amelioration of renal injury under conditions in which its reduction is directly related to the disease. Increasing evidence shows that diabetic nephropathy is also regulated by epigenetic mechanisms, including noncoding RNA. This review recapitulates the pathological, diagnostic and therapeutic potential roles of TIMP3 and the noncoding RNA (microRNA, long noncoding RNA) related to its expression, in the progression of diabetic nephropathy.

TIMP3 attenuates cerebral ischemia/reperfusion-induced apoptosis and oxidative stress in neurocytes by regulating the AKT pathway

Ischemic stroke seriously threatens human health and creates a large social burden. The present study investigated whether tissue inhibitor of metalloproteinases-3 (TIMP3) prevented cerebral ischemia/reperfusion (I/R), with the aim to explore the underlying mechanism. A transient middle cerebral artery occlusion model was conducted in mice, and oxygen glucose deprivation and reoxygenation (OGD/R) was investigated in PC12 cells to mimic cerebral ischemia-reperfusion injury (CIRI). Western blotting was used to determine the expression of TIMP3, Bax, Bcl-2 and AKT. TUNEL was used to detect apoptosis in cerebral tissues or cultured PC12 cells. Expression levels of reactive oxygen species (ROS), superoxide dismutase (SOD) and malondialdehyde (MDA) were detected to reveal oxidative stress. The results demonstrated that TIMP3 expression was significantly decreased after I/R in vivo or OGD/R in vitro, and the number of TUNEL-positive cells was reduced by the overexpression of TIMP3. The attenuation of Bax/Bcl-2 ratio in OGD/R-induced PC12 cells suppressed the expression levels of ROS and MDA; while also elevating SOD activity in the OGD/R-induced neurocytes in vitro. In addition, TIMP3-overexpression reversed the downregulation of phosphorylated-AKT (Thr308 and Ser473) in OGD/R-treated PC12 cells. However, the anti-apoptotic and anti-oxidative stress roles of TIMP3 in OGD/R-induced PC12 cells were partially abolished after treatment with the AKT inhibitor, AZD5363. Overall, TIMP3 exerted an anti-apoptotic and anti-oxidative stress role in CIRI through the AKT pathway, which may be a potential therapeutic target for the treatment of CIRI.

Contribution of ADAM17 and related ADAMs in cardiovascular diseases

A disintegrin and metalloproteases (ADAMs) are key mediators of cell signaling by ectodomain shedding of various growth factors, cytokines, receptors and adhesion molecules at the cellular membrane. ADAMs regulate cell proliferation, cell growth, inflammation, and other regular cellular processes. ADAM17, the most extensively studied ADAM family member, is also known as tumor necrosis factor (TNF)-α converting enzyme (TACE). ADAMs-mediated shedding of cytokines such as TNF-α orchestrates immune system or inflammatory cascades and ADAMs-mediated shedding of growth factors causes cell growth or proliferation by transactivation of the growth factor receptors including epidermal growth factor receptor. Therefore, increased ADAMs-mediated shedding can induce inflammation, tissue remodeling and dysfunction associated with various cardiovascular diseases such as hypertension and atherosclerosis, and ADAMs can be a potential therapeutic target in these diseases. In this review, we focus on the role of ADAMs in cardiovascular pathophysiology and cardiovascular diseases. The main aim of this review is to stimulate new interest in this area by highlighting remarkable evidence.

Quantitative Proteomics Reveals Changes Induced by TIMP-3 on Cell Membrane Composition and Novel Metalloprotease Substrates

Ectodomain shedding is a key mechanism of several biological processes, including cell-communication. Disintegrin and metalloproteinases (ADAMs), together with the membrane-type matrix metalloproteinases, play a pivotal role in shedding transmembrane proteins. Aberrant shedding is associated to several pathological conditions, including arthritis. Tissue inhibitor of metalloproteases 3 (TIMP-3), an endogenous inhibitor of ADAMs and matrix metalloproteases (MMPs), has been proven to be beneficial in such diseases. Thus, strategies to increase TIMP-3 bioavailability in the tissue have been sought for development of therapeutics. Nevertheless, high levels of TIMP-3 may lead to mechanism-based side-effects, as its overall effects on cell behavior are still unknown. In this study, we used a high-resolution mass-spectrometry-based workflow to analyze alterations induced by sustained expression of TIMP-3 in the cell surfaceome. In agreement with its multifunctional properties, TIMP-3 induced changes on the protein composition of the cell surface. We found that TIMP-3 had differential effects on metalloproteinase substrates, with several that accumulated in TIMP-3-overexpressing cells. In addition, our study identified potentially novel ADAM substrates, including ADAM15, whose levels at the cell surface are regulated by the inhibitor. In conclusion, our study reveals that high levels of TIMP-3 induce modifications in the cell surfaceome and identifies molecular pathways that can be deregulated via TIMP-3-based therapies.

Adipose Tissue Macrophage Polarization in Healthy and Unhealthy Obesity

Over 650 million adults are obese (body mass index ≥ 30 kg/m²) worldwide. Obesity is commonly associated with several comorbidities, including cardiovascular disease and type II diabetes. However, compiled estimates suggest that from 5 to 40% of obese individuals do not experience metabolic or cardiovascular complications. The existence of the metabolically unhealthy obese (MUO) and the metabolically healthy obese (MHO) phenotypes suggests that underlying differences exist in both tissues and overall systemic function. Macrophage accumulation in white adipose tissue (AT) in obesity is typically associated with insulin resistance. However, as plastic cells, macrophages respond to stimuli in their microenvironments, altering their polarization between pro- and anti-inflammatory phenotypes, depending on the state of their surroundings. The dichotomous nature of MHO and MUO clinical phenotypes suggests that differences in white AT function dictate local inflammatory responses by driving changes in macrophage subtypes. As obesity requires extensive AT expansion, we posit that remodeling capacity with adipose expansion potentiates favorable macrophage profiles in MHO as compared with MUO individuals. In this review, we discuss how differences in adipogenesis, AT extracellular matrix deposition and breakdown, and AT angiogenesis perpetuate altered AT macrophage profiles in MUO compared with MHO. We discuss how non-autonomous effects of remote organ systems, including the liver, gastrointestinal tract, and cardiovascular system, interact with white adipose favorably in MHO. Preferential AT macrophage profiles in MHO stem from sustained AT function and improved overall fitness and systemic health.

Strategies to Target ADAM17 in Disease: From its Discovery to the iRhom Revolution

For decades, disintegrin and metalloproteinase 17 (ADAM17) has been the object of deep investigation. Since its discovery as the tumor necrosis factor convertase, it has been considered a major drug target, especially in the context of inflammatory diseases and cancer. Nevertheless, the development of drugs targeting ADAM17 has been harder than expected. This has generally been due to its multifunctionality, with over 80 different transmembrane proteins other than tumor necrosis factor α (TNF) being released by ADAM17, and its structural similarity to other metalloproteinases. This review provides an overview of the different roles of ADAM17 in disease and the effects of its ablation in a number of in vivo models of pathological conditions. Furthermore, here, we comprehensively encompass the approaches that have been developed to accomplish ADAM17 selective inhibition, from the newest non-zinc-binding ADAM17 synthetic inhibitors to the exploitation of iRhom2 to specifically target ADAM17 in immune cells.

Restoration of renal TIMP3 levels via genetics and pharmacological approach prevents experimental diabetic nephropathy

BACKGROUND

Diabetic nephropathy (DN), one of the major complications of diabetes, is characterized by albuminuria, glomerulosclerosis, and progressive loss of renal function. Loss of TIMP3, an Extracellular Matrix bound protein affecting both inflammation and fibrosis, is a hallmark of DN in human subjects and mouse models.

METHODS

This study was designed to provide evidences that the modulation of the system involving TIMP3 and its target A Disintegrin And Metalloproteinase 17 (ADAM17), may rescue kidney pathology in diabetic mice. Mice with cell-targeted overexpression of TIMP3 in myeloid cells (MacT3), podocyte-specific ADAM17 knockout mice (∆PodA17), and DBA/2J mice, were rendered diabetic at 8 weeks of age with a low-dose streptozotocin protocol. DBA/2J mice were administered new peptides based on the human TIMP3 N-terminal domain, specifically conjugated with G3C12, a carrier peptide highly selective and efficient for transport to the kidney. Twelve weeks after Streptozotocin injections, 24-hour albuminuria was determined by ELISA, kidney morphometry was analyzed by periodic acid-shift staining, and Real Time-PCR and western blot analysis were performed on mRNA and protein extracted from kidney cortex.

RESULTS

Our results showed that both genetic modifications and peptides treatment positively affect renal function and structure in diabetic mice, as indicated by a significant and consistent decline in albuminuria along with reduction in glomerular lesions, as indicated by reduced mesangial expansion and glomerular hypertrophy, decreased deposition of extracellular matrix in the mesangium, diminished protein expression of the NADPH oxidases 4 (NOX4), and the improvement of podocyte structural markers such as WT1, nephrin, and podocin. Moreover, the positive effects were exerted through a mechanism independent from glycemic control.

CONCLUSIONS

In diabetic mice the targeting of TIMP3 system improved kidney structure and function, representing a valid approach to develop new avenues to treat this severe complication of diabetes.

Cutaneous and metabolic defects associated with nuclear abnormalities in a transgenic mouse model expressing R527H lamin A mutation causing mandibuloacral dysplasia type A (MADA) syndrome

LMNA gene encodes for lamin A/C, attractive proteins linked to nuclear structure and functions. When mutated, it causes different rare diseases called laminopathies. In particular, an Arginine change in Histidine in position 527 (p.Arg527His) falling in the C-terminal domain of lamin A precursor form (prelamin A) causes mandibuloacral dysplasia Type A (MADA), a segmental progeroid syndrome characterized by skin, bone and metabolic anomalies. The well-characterized cellular models made difficult to assess the tissue-specific functions of 527His prelamin A. Here, we describe the generation and characterization of a MADA transgenic mouse overexpressing 527His LMNA gene, encoding mutated prelamin A. Bodyweight is slightly affected, while no difference in lifespan was observed in transgenic animals. Mild metabolic anomalies and thinning and loss of hairs from the back were the other observed phenotypic MADA manifestations. Histological analysis of tissues relevant for MADA syndrome revealed slight increase in adipose tissue inflammatory cells and a reduction of hypodermis due to a loss of subcutaneous adipose tissue. At cellular levels, transgenic cutaneous fibroblasts displayed nuclear envelope aberrations, presence of prelamin A, proliferation, and senescence rate defects. Gene transcriptional pattern was found differentially modulated between transgenic and wildtype animals, too. In conclusion, the presence of 527His Prelamin A accumulation is further linked to the appearance of mild progeroid features and metabolic disorder without lifespan reduction.

Adipocyte ADAM17 plays a limited role in metabolic inflammation

The role of ADAM17, its substrates, and its natural inhibitor has been well studied in the context of inflammation, including metabolic inflammation, with mixed results. Previous studies examining global Adam17 knockdown models and ADAM17 inhibition using overexpression of endogenous ADAM17 inhibitors have shown improved metabolic health and decreased metabolic inflammation. However, there have been no studies examining the role of adipocyte ADAM17 using in vivo models. In this study, we developed an adipocyte-specific Adam17 knockout model using Adipoq-Cre-expressing mice crossed with Adam17-floxed mice. Using this model, we show that loss of adipocyte ADAM17 plays no evident role in baseline metabolic responses. Surprisingly, in a state of metabolic stress using high-fat diet (HFD), we observed that adipocyte ADAM17 had little effect overall on the metabolic phenotype as well as inflammatory cell populations. Using whole-body metabolic phenotyping, we show that loss of ADAM17 has no effect on energy utilization both at a baseline state as well as following HFD. However, lastly, using high-parameter flow cytometry, we show that loss of adipocyte ADAM17 alters macrophage and eosinophil populations following HFD. Overall, the studies presented here give more insight into the role of ADAM17 in metabolic responses and metabolic inflammation, specifically in adipocytes.

Cutaneous and metabolic defects associated with nuclear abnormalities in a transgenic mouse model expressing R527H lamin A mutation causing mandibuloacral dysplasia type A (MADA) syndrome

LMNA gene encodes for lamin A/C, attractive proteins linked to nuclear structure and functions. When mutated, it causes different rare diseases called laminopathies. In particular, an Arginine change in Histidine in position 527 (p.Arg527His) falling in the C-terminal domain of lamin A precursor form (prelamin A) causes mandibuloacral dysplasia Type A (MADA), a segmental progeroid syndrome characterized by skin, bone and metabolic anomalies. The well-characterized cellular models made difficult to assess the tissue-specific functions of 527His prelamin A. Here, we describe the generation and characterization of a MADA transgenic mouse overexpressing 527His LMNA gene, encoding mutated prelamin A. Bodyweight is slightly affected, while no difference in lifespan was observed in transgenic animals. Mild metabolic anomalies and thinning and loss of hairs from the back were the other observed phenotypic MADA manifestations. Histological analysis of tissues relevant for MADA syndrome revealed slight increase in adipose tissue inflammatory cells and a reduction of hypodermis due to a loss of subcutaneous adipose tissue. At cellular levels, transgenic cutaneous fibroblasts displayed nuclear envelope aberrations, presence of prelamin A, proliferation, and senescence rate defects. Gene transcriptional pattern was found differentially modulated between transgenic and wildtype animals, too. In conclusion, the presence of 527His Prelamin A accumulation is further linked to the appearance of mild progeroid features and metabolic disorder without lifespan reduction.

Timp3 deficiency affects the progression of DEN-related hepatocellular carcinoma during diet-induced obesity in mice

AIM

Obesity and low-grade inflammation are associated with an increased risk of hepatocellular carcinoma (HCC), a leading cause of cancer-related death worldwide. The tissue inhibitor of metalloproteinase (TIMP) 3, an endogenous inhibitor of protease activity that represents a key mediator of inflammation, is reduced in inflammatory metabolic disorders and cancer. In contrast, Timp3-deficient mice (Timp3^-/-) are highly resistant to developing HCC in response to a diethylnitrosamine (DEN); therefore, we aimed to elucidate the biological role of genetic loss of Timp3 in obesity-related hepatocarcinogenesis.

METHODS

Fourteen-day-old male wild-type (wt) and Timp3^-/- mice were injected with 25 mg/kg DEN or an equal volume of saline. After 4 weeks, mice were randomized into two dietary groups and fed either normal or high-fat diet and allowed to grow until 32 weeks of age. Liver histological features were analyzed, and differentially expressed genes in the liver were quantified.

RESULTS

In Timp3^-/- mice fed with the obesogenic diet, despite the increase in liver steatosis and inflammation, both the number of tumors and the total tumor size are significantly reduced 30 weeks post-DEN injection, compared to control mice. Moreover, Timp3 deletion in hepatocarcinogenesis during obesity is associated with a reduction in FoxM1 transcriptional activity through H19/miR-675/p53 pathway.

CONCLUSIONS

This study suggests that Timp3 ablation leads to cell cycle perturbation, at least in part by repressing FoxM1 transcriptional activity through H19/miR-675/p53 pathway.

Inhibition of microRNA-222 up-regulates TIMP3 to promotes osteogenic differentiation of MSCs from fracture rats with type 2 diabetes mellitus

Type 2 diabetes mellitus (T2DM) is the most common diabetes and has numerous complications. Recent studies demonstrated that T2DM compromises bone fracture healing in which miR-222 might be involved. Furthermore, tissue inhibitor of metalloproteinase 3 (TIMP-3) that is the target of miR-222 accelerates fracture healing. Therefore, we assume that miR-222 could inhibit TIMP-3 expression. Eight-week-old rats were operated femoral fracture or sham, following the injection of streptozotocin (STZ) to induce diabetes one week later in fractured rats, and then, new generated tissues were collected for measuring the expression of miR-222 and TIMP-3. Rat mesenchymal stem cells (MSCs) were isolated and treated with miR-222 mimic or inhibitor to analyse osteogenic differentiation. MiR-222 was increased in fractured rats and further induced in diabetic rats. In contrast, TIMP-3 was reduced in fractured and further down-regulated in diabetic rats. Luciferase report assay indicated miR-222 directly binds and mediated TIMP-3. Furthermore, osteogenic differentiation was suppressed by miR-222 mimic and promoted by miR-222 inhibitor. miR-222 is a key regulator that is promoted in STZ-induced diabetic rats, and it binds to TIMP3 to reduce TIMP-3 expression and suppressed MSCs' differentiation.

Extracellular Matrix Remodeling of Adipose Tissue in Obesity and Metabolic Diseases

The extracellular matrix (ECM) is a network of different proteins and proteoglycans that controls differentiation, migration, repair, survival, and development, and it seems that its remodeling is required for healthy adipose tissue expansion. Obesity drives an excessive lipid accumulation in adipocytes, which provokes immune cells infiltration, fibrosis (an excess of deposition of ECM components such as collagens, elastin, and fibronectin) and inflammation, considered a consequence of local hypoxia, and ultimately insulin resistance. To understand the mechanism of this process is a challenge to treat the metabolic diseases. This review is focused at identifying the putative role of ECM in adipose tissue, describing its structure and components, its main tissue receptors, and how it is affected in obesity, and subsequently the importance of an appropriate ECM remodeling in adipose tissue expansion to prevent metabolic diseases.

Identification of lncRNAs and Genes Responsible for Fatness and Fatty Acid Composition Traits between the Tibetan and Yorkshire Pigs

Tibetan pigs from the Tibetan Plateau are characterized with a significant phenotypic difference relative to lowland pigs. In this study, a significant difference of the fatness and fatty acid composition traits was observed between the Tibetan and Yorkshire pigs. To uncover the involved mechanism, the expression profile of long noncoding RNAs (lncRNAs) and genes was compared between them. After serial filtered steps, 1,964 lncRNAs were obtained through our computational pipeline. In total, 63 and 715 lncRNAs and genes were identified to be differentially expressed. Evidence from cis- and trans-targeting analysis of lncRNAs demonstrated that some lncRNAs, such as MSTRG.14097 and MSTRG.8034, played important roles in the fatness and fatty acid composition traits. Bioinformatics analysis revealed that many candidate genes were responsible for the two traits. Of these, FASN, ACACA, SCD, ME3, PDHB, ACSS1, ACSS2, and ACLY were identified, which functioned in regulating the level of hexadecanoic acid, hexadecenoic acid, octadecenoic acid, and monounsaturated fatty acid. And LPGAT1, PDK4, ACAA1, and ADIPOQ were associated with the content of stearic acid, octadecadienoic acid, and polyunsaturated fatty acid. Candidate genes, which were responsible for fatness trait, consisted of FGF2, PLAG1, ADIPOQ, IRX3, MIF, IL-34, ADAM8, HMOX1, Vav1, and TLR8. In addition, association analysis also revealed that 34 and 57 genes significantly correlated to the fatness and fatty acid composition trait, respectively. Working out the mechanism caused by these lncRNAs and candidate genes is proven to be complicated but is invaluable to our understanding of fatness and fatty acid composition traits.

Exosome and Macrophage Crosstalk in Sleep-Disordered Breathing-Induced Metabolic Dysfunction

Obstructive sleep apnea (OSA) is a highly prevalent worldwide public health problem that is characterized by repetitive upper airway collapse leading to intermittent hypoxia, pronounced negative intrathoracic pressures, and recurrent arousals resulting in sleep fragmentation. Obesity is a major risk factor of OSA and both of these two closely intertwined conditions result in increased sympathetic activity, oxidative stress, and chronic low-grade inflammation, which ultimately contribute, among other morbidities, to metabolic dysfunction, as reflected by visceral white adipose tissue (VWAT) insulin resistance (IR). Circulating extracellular vesicles (EVs), including exosomes, are released by most cell types and their cargos vary greatly and reflect underlying changes in cellular homeostasis. Thus, exosomes can provide insights into how cells and systems cope with physiological perturbations by virtue of the identity and abundance of miRNAs, mRNAs, proteins, and lipids that are packaged in the EVs cargo, and are secreted from the cells into bodily fluids under normal as well as diseased states. Accordingly, exosomes represent a novel pathway via which a cohort of biomolecules can travel long distances and result in the modulation of gene expression in selected and targeted recipient cells. For example, exosomes secreted from macrophages play a critical role in innate immunity and also initiate the adaptive immune response within specific metabolic tissues such as VWAT. Under normal conditions, phagocyte-derived exosomes represent a large portion of circulating EVs in blood, and carry a protective signature against IR that is altered when secreting cells are exposed to altered physiological conditions such as those elicited by OSA, leading to emergence of IR within VWAT compartment. Consequently, increased understanding of exosome biogenesis and biology should lead to development of new diagnostic biomarker assays and personalized therapeutic approaches. Here, the evidence on the major biological functions of macrophages and exosomes as pathophysiological effectors of OSA-induced metabolic dysfunction is discussed.

Targeting hepatic miR-221/222 for therapeutic intervention of nonalcoholic steatohepatitis in mice

Background

Effective targeting therapies for common chronic liver disease nonalcoholic steatohepatitis (NASH) are in urgent need. MicroRNA-targeted therapeutics would be potentially an effective treatment strategy of hepatic diseases. Here we investigated the functional role of miR-221/222 and the therapeutic effects of antimiRs-221/222 in NASH mouse models.

Methods

We generated the miR-221/222^flox/flox mice on a C57BL/6 J background and the hepatic miR-221/222 knockout (miR-221/222-LKO) mice. The mice were challenged with the methionine and choline deficient diet (MCDD) or chronic carbon tetrachloride (CCl₄) treatment to generate experimental steatohepatitis models. Adenovirus-mediated re-expression of miR-221/222 was performed on the MCDD-fed miR-221/222-LKO mice. The MCDD and control diet-fed mice were treated with locked nucleic acid (LNA)-based antimiRs of miR-221/222 to evaluate the therapeutic effects. Histological analysis, RNA-seq, quantitative PCR and Western blot of liver tissues were carried out to study the hepatic lipid accumulation, inflammation and collagen deposition in mouse models.

Findings

Hepatic deletion of miR-221/222 resulted in significant reduction of liver fibrosis, lipid deposition and inflammatory infiltration in the MCDD-fed and CCl4-treated mouse models. The hepatic steatosis and fibrosis were dramatically aggravated by miR-221/222 re-expression in MCDD-fed miR-221/222-LKO mice. AntimiRs of miR-221/222 could effectively reduce the MCDD-mediated hepatic steatosis and fibrosis. Systematically mechanistic study revealed that hepatic miR-221/222 controlled the expression of target gene Timp3 and promoted the progression of NASH.

Interpretation

Our findings demonstrate that miR-221/222 are crucial for the regulation of lipid metabolism, inflammation and fibrosis in the liver. LNA-antimiRs targeted miR-221/222 could reduce steatohepatitis with prominent antifibrotic effect in NASH mice.

Fund

This work is supported by the Natural Science Foundation of China (81530020, 81390352 to Dr. Ning and 81522032 to Dr. Cao and 81670793 to Dr. Jiang); National Key Research and Development Program (No. 2016YFC0905001 and 2017YFC0909703 to Dr. Cao); the Shanghai Rising-Star Program (15QA1402900 to Dr. Cao); Shanghai Municipal Education Commission-Gaofeng Clinical Medicine Grant (20171905 to Dr. Jiang).

Gene regulation underlies environmental adaptation in house mice

Changes in cis-regulatory regions are thought to play a major role in the genetic basis of adaptation. However, few studies have linked cis-regulatory variation with adaptation in natural populations. Here, using a combination of exome and RNA-seq data, we performed expression quantitative trait locus (eQTL) mapping and allele-specific expression analyses to study the genetic architecture of regulatory variation in wild house mice (Mus musculus domesticus) using individuals from five populations collected along a latitudinal cline in eastern North America. Mice in this transect showed clinal patterns of variation in several traits, including body mass. Mice were larger in more northern latitudes, in accordance with Bergmann's rule. We identified 17 genes where cis-eQTLs were clinal outliers and for which expression level was correlated with latitude. Among these clinal outliers, we identified two genes (Adam17 and Bcat2) with cis-eQTLs that were associated with adaptive body mass variation and for which expression is correlated with body mass both within and between populations. Finally, we performed a weighted gene co-expression network analysis (WGCNA) to identify expression modules associated with measures of body size variation in these mice. These findings demonstrate the power of combining gene expression data with scans for selection to identify genes involved in adaptive phenotypic evolution, and also provide strong evidence for cis-regulatory elements as essential loci of environmental adaptation in natural populations.

Macrophage Polarization in Chronic Inflammatory Diseases: Killers or Builders?

Macrophages are key cellular components of the innate immunity, acting as the main player in the first-line defence against the pathogens and modulating homeostatic and inflammatory responses. Plasticity is a major feature of macrophages resulting in extreme heterogeneity both in normal and in pathological conditions. Macrophages are not homogenous, and they are generally categorized into two broad but distinct subsets as either classically activated (M1) or alternatively activated (M2). However, macrophages represent a continuum of highly plastic effector cells, resembling a spectrum of diverse phenotype states. Induction of specific macrophage functions is closely related to the surrounding environment that acts as a relevant orchestrator of macrophage functions. This phenomenon, termed polarization, results from cell/cell, cell/molecule interaction, governing macrophage functionality within the hosting tissues. Here, we summarized relevant cellular and molecular mechanisms driving macrophage polarization in "distant" pathological conditions, such as cancer, type 2 diabetes, atherosclerosis, and periodontitis that share macrophage-driven inflammation as a key feature, playing their dual role as killers (M1-like) and/or builders (M2-like). We also dissect the physio/pathological consequences related to macrophage polarization within selected chronic inflammatory diseases, placing polarized macrophages as a relevant hallmark, putative biomarkers, and possible target for prevention/therapy.

Proteomic and metabolomic characterization of streptozotocin-induced diabetic nephropathy in TIMP3-deficient mice

AIMS

The tissue inhibitor of metalloproteinase TIMP3 is a stromal protein that restrains the activity of both protease and receptor in the extracellular matrix and has been found to be down-regulated in diabetic nephropathy (DN), the leading cause of end-stage renal disease in developed countries.

METHODS

In order to gain deeper insights on the association of loss of TIMP3 and DN, we performed differential proteomic analysis of kidney and blood metabolic profiling of wild-type and Timp3-knockout mice before and after streptozotocin (STZ) treatment, widely used to induce insulin deficiency and hyperglycemia.

RESULTS

Kidney proteomic data and blood metabolic profiles suggest significant alterations of peroxisomal and mitochondrial fatty acids β-oxidation in Timp3-knockout mice compared to wild-type mice under basal condition. These alterations were exacerbated in response to STZ treatment.

CONCLUSIONS

Proteomic and metabolomic approaches showed that loss of TIMP3 alone or in combination with STZ treatment results in significant alterations of kidney lipid metabolism and peripheral acylcarnitine levels, supporting the idea that loss of TIMP3 may generate a phenotype more prone to DN.

Macrophage Polarization in Chronic Inflammatory Diseases: Killers or Builders?

Macrophages are key cellular components of the innate immunity, acting as the main player in the first-line defence against the pathogens and modulating homeostatic and inflammatory responses. Plasticity is a major feature of macrophages resulting in extreme heterogeneity both in normal and in pathological conditions. Macrophages are not homogenous, and they are generally categorized into two broad but distinct subsets as either classically activated (M1) or alternatively activated (M2). However, macrophages represent a continuum of highly plastic effector cells, resembling a spectrum of diverse phenotype states. Induction of specific macrophage functions is closely related to the surrounding environment that acts as a relevant orchestrator of macrophage functions. This phenomenon, termed polarization, results from cell/cell, cell/molecule interaction, governing macrophage functionality within the hosting tissues. Here, we summarized relevant cellular and molecular mechanisms driving macrophage polarization in “distant” pathological conditions, such as cancer, type 2 diabetes, atherosclerosis, and periodontitis that share macrophage-driven inflammation as a key feature, playing their dual role as killers (M1-like) and/or builders (M2-like). We also dissect the physio/pathological consequences related to macrophage polarization within selected chronic inflammatory diseases, placing polarized macrophages as a relevant hallmark, putative biomarkers, and possible target for prevention/therapy.

Hepatocyte specific TIMP3 expression prevents diet dependent fatty liver disease and hepatocellular carcinoma

Non-alcoholic fatty liver disease (NAFLD) encompasses a broad spectrum of conditions, ranging from non-progressive bland steatosis to hepatocarcinoma. Tissue inhibitor of metalloproteinase 3 (Timp3) has a role in the pathogenesis of fatty liver disease associated with obesity and is silenced during metabolic disorders and liver cancer. We generated an hepatocyte-specific TIMP3 'gain-of-function' mouse model under the control of the Albumin promoter (AlbT3) and investigated its effects during high-fat diet (HFD). After 16 weeks of HFD, TIMP3 overexpression significantly improved glucose metabolism, hepatic fatty acid oxidation and cholesterol homeostasis. In AlbT3 mice CYP7A1, MDR3 and MRP2 gene expressions were observed, consistent with higher bile acid synthesis and export. Next, to evaluate the role of A Disintegrin and Metalloproteinase 17 (ADAM17), a crucial target of TIMP3, in these processes, we created mice deficient in Adam17 specifically in hepatocyte (A17LKO) or in myeloid lineage (A17MKO), founding that only A17LKO showed improvement in liver steatosis induced by HFD. Moreover, both, AlbT3 and A17LKO significantly reduced diethylnitrosamine-initiated, HFD-promoted hepatic tumorigenesis assessed by tumor multiplicity and total tumor area. Taken together, these data indicate that hepatic TIMP3 can slow progression of NAFLD, and tumorigenesis, at least in part, through the regulation of ADAM17 activity.

Absence of Tissue Inhibitor of Metalloproteinase-4 (TIMP4) ameliorates high fat diet-induced obesity in mice due to defective lipid absorption

Tissue inhibitor of metalloproteases (TIMPs) are inhibitors of matrix metalloproteinases (MMPs) that regulate tissue extracellular matrix (ECM) turnover. TIMP4 is highly expressed in adipose tissue, its levels are further elevated following high-fat diet, but its role in obesity is unknown. Eight-week old wild-type (WT) and Timp4-knockout (Timp4 -/-) mice received chow or high fat diet (HFD) for twelve weeks. Timp4 -/- mice exhibited a higher food intake but lower body fat gain. Adipose tissue of Timp4 -/- -HFD mice showed reduced hypertrophy and fibrosis compared to WT-HFD mice. Timp4 -/- -HFD mice were also protected from HFD-induced liver and skeletal muscle triglyceride accumulation and dyslipidemia. Timp4 -/--HFD mice exhibited reduced basic metabolic rate and energy expenditure, but increased respiratory exchange ratio. Increased free fatty acid excretion was detected in Timp4 -/--HFD compared to WT-HFD mice. CD36 protein, the major fatty acid transporter in the small intestine, increased with HFD in WT but not in Timp4 -/- mice, despite a similar rise in Cd36 mRNA in both genotypes. Consistently, HFD increased enterocyte lipid content only in WT but not in Timp4 -/- mice. Our study reveals that absence of TIMP4 can impair lipid absorption and the high fat diet-induced obesity in mice possibly by regulating the proteolytic processing of CD36 protein in the intestinal enterocytes.

A Role for Timp3 in Microbiota-Driven Hepatic Steatosis and Metabolic Dysfunction

The effect of gut microbiota on obesity and insulin resistance is now recognized, but the underlying host-dependent mechanisms remain poorly undefined. We find that tissue inhibitor of metalloproteinase 3 knockout (Timp3(-/-)) mice fed a high-fat diet exhibit gut microbiota dysbiosis, an increase in branched chain and aromatic (BCAA) metabolites, liver steatosis, and an increase in circulating soluble IL-6 receptors (sIL6Rs). sIL6Rs can then activate inflammatory cells, such as CD11c(+) cells, which drive metabolic inflammation. Depleting the microbiota through antibiotic treatment significantly improves glucose tolerance, hepatic steatosis, and systemic inflammation, and neutralizing sIL6R signaling reduces inflammation, but only mildly impacts glucose tolerance. Collectively, our results suggest that gut microbiota is the primary driver of the observed metabolic dysfunction, which is mediated, in part, through IL-6 signaling. Our findings also identify an important role for Timp3 in mediating the effect of the microbiota in metabolic diseases.

Adipose extracellular matrix remodelling in obesity and insulin resistance

The extracellular matrix (ECM) of adipose tissues undergoes constant remodelling to allow adipocytes and their precursor cells to change cell shape and function in adaptation to nutritional cues. Abnormal accumulation of ECM components and their modifiers in adipose tissues has been recently demonstrated to cause obesity-associated insulin resistance, a hallmark of type 2 diabetes. Integrins and other ECM receptors (e.g. CD44) that are expressed in adipose tissues have been shown to regulate insulin sensitivity. It is well understood that a hypoxic response is observed in adipose tissue expansion during obesity progression and that hypoxic response accelerates fibrosis and inflammation in white adipose tissues. The expansion of adipose tissues should require angiogenesis; however, the excess deposition of ECM limits the angiogenic response of white adipose tissues in obesity. While recent studies have focused on the metabolic consequences and the mechanisms of adipose tissue expansion and remodelling, little attention has been paid to the role played by the interaction between peri-adipocyte ECM and their cognate cell surface receptors. This review will address what is currently known about the roles played by adipose ECM, their modifiers, and ECM receptors in obesity and insulin resistance. Understanding how excess ECM deposition in the adipose tissue deteriorates insulin sensitivity would provide us hints to develop a new therapeutic strategy for the treatment of insulin resistance and type 2 diabetes.

Skeletal muscle TLR4 and TACE are associated with body fat percentage in older adults

Elevated skeletal muscle expression of toll-like receptor 4 (TLR4) has been linked to increased inflammation in clinical populations. TNFα converting enzyme (TACE), which cleaves membrane-bound TNFα (mTNFα) to its soluble (sTNFα) and more bioactive form, has been linked to chronic disease. In contrast, higher physical activity level is associated with decreased chronic disease risk and inflammation. The purpose of the present study was to examine the relationship between physical activity and skeletal muscle TLR4, TACE, and TNFα in older adults. In 26 older adults (age = 68 ± 4 years, body mass index = 26 ± 3 kg·m(-2)), self-reported physical activity (kcal·week(-1)), estimated maximal oxygen consumption, and body composition (air plethysmography) were measured. TLR4, TACE, mTNFα, and sTNFα were measured in skeletal muscle biopsies (vastus lateralis) using western blot analyses. Pearson product-moment correlations were run between variables. Significance was set at p < 0.05. Skeletal muscle TACE was directly associated with sTNFα (r = 0.53, p < 0.01). Linear regression modeling showed that mTNFα and TACE expression were predictive of sTNFα expression. No correlations were observed between physical activity and TLR4, TACE, or sTNFα. Percent body fat was directly associated with skeletal muscle TLR4 (r = 0.52, p < 0.01) and TACE (r = 0.50, p < 0.01), whereas fasting blood glucose was directly associated with TACE and sTNFα. In conclusion, we found that percent body fat was directly associated with TLR4 and TACE expression in skeletal muscle of older adults. These findings suggest that elevated skeletal muscle expression of TLR4 and TACE may contribute to the augmented inflammation and chronic disease risk observed with increased adiposity.

Hepatic lipase deficiency produces glucose intolerance, inflammation and hepatic steatosis

Metabolic syndrome and type 2 diabetes mellitus constitute a major problem to global health, and their incidence is increasing at an alarming rate. Non-alcoholic fatty liver disease, which affects up to 90% of obese people and nearly 70% of the overweight, is commonly associated with MetS characteristics such as obesity, insulin resistance, hypertension and dyslipidemia. In the present study, we demonstrate that hepatic lipase (HL)-inactivation in mice fed with a high-fat, high-cholesterol diet produced dyslipidemia including hypercholesterolemia, hypertriglyceridemia and increased non-esterified fatty acid levels. These changes were accompanied by glucose intolerance, pancreatic and hepatic inflammation and steatosis. In addition, compared with WT mice, HL(-/-) mice exhibited enhanced circulating MCP1 levels, monocytosis and higher percentage of CD4+Th17+ cells. Consistent with increased inflammation, livers from HL(-/-) mice had augmented activation of the stress SAPK/JNK- and p38-pathways compared with the activation levels of the kinases in livers from WT mice. Analysis of HL(-/-) and WT mice fed regular chow diet showed dyslipidemia and glucose intolerance in HL(-/-) mice without any other changes in inflammation or hepatic steatosis. Altogether, these results indicate that dyslipidemia induced by HL-deficiency in combination with a high-fat, high-cholesterol diet promotes hepatic steatosis and inflammation in mice which are, at least in part, mediated by the activation of the stress SAPK/JNK- and p38-pathways. Future studies are warranted to asses the viability of therapeutic strategies based on the modulation of these kinases to reduce hepatic steatosis associated to lipase dysfunction.

TIMP3 interplays with apelin to regulate cardiovascular metabolism in hypercholesterolemic mice

OBJECTIVE

Tissue inhibitor of metalloproteinase 3 (TIMP3) is an extracellular matrix (ECM) bound protein, which has been shown to be downregulated in human subjects and experimental models with cardiometabolic disorders, including type 2 diabetes mellitus, hypertension and atherosclerosis. The aim of this study was to investigate the effects of TIMP3 on cardiac energy homeostasis during increased metabolic stress conditions.

METHODS

ApoE(-/-)TIMP3(-/-) and ApoE(-/-) mice on a C57BL/6 background were subjected to telemetric ECG analysis and experimental myocardial infarction as models of cardiac stress induction. We used Western blot, qRT-PCR, histology, metabolomics, RNA-sequencing and in vivo phenotypical analysis to investigate the molecular mechanisms of altered cardiac energy metabolism.

RESULTS

ApoE(-/-)TIMP3(-/-) revealed decreased lifespan. Telemetric ECG analysis showed increased arrhythmic episodes, and experimental myocardial infarction by left anterior descending artery (LAD) ligation resulted in increased peri-operative mortality together with increased scar formation, ventricular dilatation and a reduction of cardiac function after 4 weeks in the few survivors. Hearts of ApoE(-/-)TIMP3(-/-) exhibited accumulation of neutral lipids when fed a chow diet, which was exacerbated by a high fat, high cholesterol diet. Metabolomics analysis revealed an increase in circulating markers of oxidative stress with a reduction in long chain fatty acids. Using whole heart mRNA sequencing, we identified apelin as a putative modulator of these metabolic defects. Apelin is a regulator of fatty acid oxidation, and we found a reduction in the levels of enzymes involved in fatty acid oxidation in the left ventricle of ApoE(-/-)TIMP3(-/-) mice. Injection of apelin restored the hitherto identified metabolic defects of lipid oxidation.

CONCLUSION

TIMP3 regulates lipid metabolism as well as oxidative stress response via apelin. These findings therefore suggest that TIMP3 maintains metabolic flexibility in the heart, particularly during episodes of increased cardiac stress.

The extracellular matrix and insulin resistance

The extracellular matrix (ECM) is a highly-dynamic compartment that undergoes remodeling as a result of injury and repair. Over the past decade, mounting evidence in humans and rodents suggests that ECM remodeling is associated with diet-induced insulin resistance in several metabolic tissues. In addition, integrin receptors for the ECM have also been implicated in the regulation of insulin action. This review addresses what is currently known about the ECM, integrins, and insulin action in the muscle, liver, and adipose tissue. Understanding how ECM remodeling and integrin signaling regulate insulin action may aid in the development of new therapeutic targets for the treatment of insulin resistance and type 2 diabetes (T2D).

Absence of nicotinic acetylcholine receptor α7 subunit amplifies inflammation and accelerates onset of fibrosis: an inflammatory kidney model

Inflammation is regulated by endogenous mechanisms, including anti-inflammatory cytokines, adenosine, and the nicotinic acetylcholine receptor α7 subunit (α7nAChR). We investigated the role of α7nAChR in protection against the progression of tissue injury in a model of severe, macrophage-mediated, cytokine-dependent anti-glomerular basement membrane (GBM) glomerulonephritis (GN), in α7nAChR-deficient (α7(-/-)) mice . At d 7 after the injection of anti-GBM antibody, kidneys from α7(-/-) mice displayed severe glomeruli (P < 0.0001) and tubulointerstitial lesions (P < 0.001) compared to kidneys from WT mice. An important finding was the presence of severe glomerulosclerosis in α7(-/-) mice in this early phase of the disease. Kidneys of α7(-/-) mice showed greater accumulation of inflammatory cells and higher expression of chemokines and cytokines than did those of WT mice. In addition, in α7(-/-) fibrotic kidneys, the expression of fibrin, collagen, TGF-β, and tissue inhibitor of metalloproteinase (TIMP)-2 increased, and the expression of TIMP3 declined. The increase in counterregulatory responses to inflammation in α7(-/-) nephritic kidneys did not compensate for the lack of α7nAChR. These findings indicate that α7nAChR plays a key role in regulating the inflammatory response in anti-GBM GN and that disruption of the endogenous protective α7nAChR amplifies inflammation to accelerate kidney damage and fibrosis.

Concise Review: New Insights Into the Role of Macrophages in β-Cell Proliferation

Diabetes mellitus can potentially be treated with islet transplantation, but additional sources of β cells are necessary to overcome the short supply of donor pancreases. Although controversy still exists, it is generally believed that the postnatal expansion of the β-cell mass is mainly through pre-existing β-cell replication. Thus, understanding the molecular mechanisms underlying the regulation of β-cell proliferation might lead to clinical strategies for increasing β-cell numbers, both in vitro and in vivo. Macrophages have a well-recognized role in the development of insulitis as part of the pathogenesis of type 1 diabetes. However, a potential role for macrophage polarization, triggered by specific environmental stimuli, in promoting β-cell proliferation has only recently been appreciated. In the present review, we discuss several independent studies, using different regeneration models, that demonstrate a substantial inductive role for macrophages in β-cell proliferation. Additional dissection of the involved cell-cell crosstalk through specific signal transduction pathways is expected to improve our understanding of β-cell proliferation and might facilitate the current β-cell replacement therapy.

SIGNIFICANCE

New independent findings from different β-cell regeneration models, contributed by different research groups, have provided compelling evidence to highlight a previously unappreciated role for macrophages in β-cell proliferation. Additional dissection of the underlying mechanisms and cell-cell crosstalk might shed new light on strategies to increase the functional β-cell mass in vivo and on β-cell replacement therapies.

Macrophage-specific overexpression of interleukin-5 attenuates atherosclerosis in LDL receptor-deficient mice

Interleukin-5 (IL-5) increases the secretion of natural T15/EO6 IgM antibodies that inhibit the uptake of oxidized low-density lipoprotein (LDL) by macrophages. This study aimed to determine whether macrophage-specific expression of IL-5 in LDL receptor-deficient mice (Ldlr(-/-)) could improve cholesterol metabolism and reduce atherosclerosis. To induce macrophage-specific IL-5 expression, the pLVCD68-IL5 lentivirus was delivered into Ldlr(-/-) mice via bone marrow transplantation. The recipient mice were fed a Western-type diet for 12 weeks to induce lesion formation. We found that IL-5 was efficiently and specifically overexpressed in macrophages in recipients of pLVCD68-IL5-transduced bone marrow cells (BMC). Plasma titers of T15/EO6 IgM antibodies were significantly elevated by 58% compared with control mice transplanted with pLVCD68 lacking the IL-5 coding sequence. Plaque areas of aortas in IL-5-overexpressing mice were reduced by 43% and associated with a 2.4-fold decrease in lesion size at the aortic roots when compared with mice receiving pLVCD68-transduced BMCs. The study showed that macrophage-specific overexpression of IL-5 inhibited the progression of atherosclerotic lesions. These findings suggest that modulation of IL-5 cytokine expression represents a potential strategy for intervention of familial hypercholesterolemia and other cardiovascular diseases.

Atlantic salmon (Salmo salar) liver transcriptome response to diets containing Camelina sativa products

Due to increasing demand for fish oil (FO) and fish meal (FM) in aquafeeds, more sustainable alternatives such as plant-derived oils and proteins are needed. Camelina sativa products are viable feed ingredients given the high oil and crude protein content in the seed. Atlantic salmon were fed diets with complete or partial replacement of FO and/or FM with camelina oil (CO) and/or camelina meal (CM) in a 16-week trial [Control diet: FO; Test diets: 100% CO replacement of FO (100CO), or 100CO with solvent-extracted FM (100COSEFM), 10% CM (100CO10CM), or SEFM+10% CM (100COSEFM10CM)]. Diet composition, growth, and fatty acid analyses for this feeding trial were published previously. A 44K microarray experiment identified liver transcripts that responded to 100COSEFM10CM (associated with reduced growth) compared to controls, yielding 67 differentially expressed features (FDR<5%). Ten microarray-identified genes [cpt1, pcb, bar, igfbp-5b (2 paralogues), btg1, dnph1, lect-2, clra, klf9, and fadsd6a], and three additional genes involved in lipid metabolism [elovl2, elovl5 (2 paralogues), and fadsd5], were subjected to QPCR with liver templates from all 5 dietary treatments. Of the microarray-identified genes, only bar was not QPCR validated. Both igfbp-5b paralogues were significantly down-regulated, and fadsd6a was significantly up-regulated, in all 4 camelina-containing diet groups compared with controls. Multivariate statistics were used to correlate hepatic desaturase and elongase gene expression data with tissue fatty acid profiles, indicating the involvement of these genes in LC-PUFA biosynthesis. This nutrigenomic study provides molecular biomarkers for use in developing novel aquafeeds using camelina products.

Macrophage recruitment in obese adipose tissue

Obesity is characterized as a chronic state of low-grade inflammation with progressive immune cell infiltration into adipose tissues. Adipose tissue macrophages play critical roles in the establishment of the chronic inflammatory state and metabolic dysfunctions. The novel discovery that pro-inflammatory macrophages are recruited to obese adipose tissue prompted an increased interest in the interplay between immune cells and metabolism. Since this discovery, many works have been published investigating the factors that lead to macrophage recruitment, the phenotypic change of adipose tissue macrophages, and metabolic dysfunctions. Adipokines and chemokines are key mediators that play crucial roles in crosstalk between adipocytes and macrophages and in regulating the adipose tissue inflammation. In the present review, we discuss the obesity-mediated adipose tissue remodelling, and particularly, the role of adipokines/chemokines in macrophage recruitment to obese adipose tissue. This review provides new insights into the physiological role of these factors and identifies a potential therapeutic target for obesity and associated disorders.

ADAM17 at the interface between inflammation and autoimmunity

The discovery of the disintegrin and metalloproteinase 17 (ADAM17), originally identified as tumor necrosis factor-a converting enzyme (TACE) for its ability as sheddase of TNF-α inspired scientists to attempt to elucidate the molecular mechanisms underlying ADAM17 implication in diseased conditions. In recent years, it has become evident that this protease can modify many non matrix substrates, such as cytokines (e.g. TNF-α), cytokine receptors (e.g. IL-6R and TNF-R), ligands of ErbB (e.g. TGF-α and amphiregulin) and adhesion proteins (e.g. Lselectin and ICAM-1). Several recent studies have described experimental model system to better understand the role of specific signaling molecules, the interplay of different signals and tissue interactions in regulating ADAM17-dependent cleavage of most relevant substrates in inflammatory diseases. The central question is whether ADAM17 can influence the outcome of inflammation and if so, how it performs this regulation in autoimmunity, since inflammatory autoimmune diseases are often characterized by deregulated metalloproteinase activities. This review will explore the latest research on the influence of ADAM17 on the progression of inflammatory processes linked to autoimmunity and its role as modulator of inflammation.

IL-21 is a major negative regulator of IRF4-dependent lipolysis affecting Tregs in adipose tissue and systemic insulin sensitivity

Obesity elicits immune cell infiltration of adipose tissue provoking chronic low-grade inflammation. Regulatory T cells (Tregs) are specifically reduced in adipose tissue of obese animals. Since interleukin (IL)-21 plays an important role in inducing and maintaining immune-mediated chronic inflammatory processes and negatively regulates Treg differentiation/activity, we hypothesized that it could play a role in obesity-induced insulin resistance. We found IL-21 and IL-21R mRNA expression upregulated in adipose tissue of high-fat diet (HFD) wild-type (WT) mice and in stromal vascular fraction from human obese subjects in parallel to macrophage and inflammatory markers. Interestingly, a larger infiltration of Treg cells was seen in the adipose tissue of IL-21 knockout (KO) mice compared with WT animals fed both normal diet and HFD. In a context of diet-induced obesity, IL-21 KO mice, compared with WT animals, exhibited lower body weight, improved insulin sensitivity, and decreased adipose and hepatic inflammation. This metabolic phenotype is accompanied by a higher induction of interferon regulatory factor 4 (IRF4), a transcriptional regulator of fasting lipolysis in adipose tissue. Our data suggest that IL-21 exerts negative regulation on IRF4 and Treg activity, developing and maintaining adipose tissue inflammation in the obesity state.

Macrophages and the regulation of adipose tissue remodeling

The ability of adipose tissue to adapt to a changing nutrient environment is critical to the maintenance of metabolic control. Nutrient excess and deficiency alter the shape of adipose tissue drastically and trigger many events that are collectively known as adipose tissue remodeling. Remodeling of adipose tissue involves more than adipocytes and is controlled by an extensive network of stromal cells and extracellular matrix proteins. Prominent players in this process are adipose tissue macrophages, which are a specialized leukocyte present in lean and obese states that contributes to adipose tissue inflammation. The interest in adipose tissue remodeling has been accelerated by the current epidemic of obesity and the chronic generation of signals that lead to expansion of adipose tissue. It is clear that evidence of dysfunctional remodeling events is a hallmark of obesity associated with metabolic disease. This review summarizes and highlights the recent work in this area and provides a framework in which to consider how adipose tissue macrophages contribute to the remodeling events in lean and obese states. Advancing our understanding of the involvement of macrophages in adipose tissue remodeling will promote one aspect of the new field of "immunometabolism," which connects control systems developed for regulation of immunity with those that control metabolism. It will also provide insight into how physiologic and pathophysiologic remodeling differs in adipose tissue and identify potential nodes for intervention to break the link between obesity and disease.

Functional roles of protein nitration in acute and chronic liver diseases

Nitric oxide, when combined with superoxide, produces peroxynitrite, which is known to be an important mediator for a number of diseases including various liver diseases. Peroxynitrite can modify tyrosine residue(s) of many proteins resulting in protein nitration, which may alter structure and function of each target protein. Various proteomics and immunological methods including mass spectrometry combined with both high pressure liquid chromatography and 2D PAGE have been employed to identify and characterize nitrated proteins from pathological tissue samples to determine their roles. However, these methods contain a few technical problems such as low efficiencies with the detection of a limited number of nitrated proteins and labor intensiveness. Therefore, a systematic approach to efficiently identify nitrated proteins and characterize their functional roles is likely to shed new insights into understanding of the mechanisms of hepatic disease pathophysiology and subsequent development of new therapeutics. The aims of this review are to briefly describe the mechanisms of hepatic diseases. In addition, we specifically describe a systematic approach to efficiently identify nitrated proteins to study their causal roles or functional consequences in promoting acute and chronic liver diseases including alcoholic and nonalcoholic fatty liver diseases. We finally discuss translational research applications by analyzing nitrated proteins in evaluating the efficacies of potentially beneficial agents to prevent or treat various diseases in the liver and other tissues.

Association between ADAM17 promoter polymorphisms and ischemic stroke in a Chinese population

AIM

Stroke is a leading cause of death and disability worldwide. Most ischemic strokes (IS) are caused by atherosclerosis. Recently, the pivotal role of ADAM17 in atherosclerosis has been thoroughly addressed. However, the association between ADAM17 and IS has not yet been thoroughly explored. The present study therefore aimed to investigate the association between disintegrin and metalloproteinase 17 (ADAM17) gene polymorphisms and the risk of ischemic stroke (IS).

METHODS

The associations between five ADAM17 promoter polymorphisms and the risk of IS were assessed in 342 patients with IS and 296 age-matched healthy individuals in a case-control study.

RESULTS

The allele and genotype frequencies of the ADAM17 polymorphisms (rs11684747, rs11689958, rs12692386, rs55790676 and rs1524668) did not differ significantly between the IS patients and healthy control group subjects. In addition, no significant associations were detected between the ADAM17 haplotypes and IS. The mean intima-media thickness in the IS patients was not associated with the ADAM17 polymorphisms. When the IS patients were stratified according to their OCSP classification, the genotype frequencies of the ADAM17-rs1524668 polymorphism exhibited a significant association with the PACI subtype of IS. Moreover, the ADAM17-rs12692386 A＞G polymorphism was found to be associated with a higher ADAM17 mRNA expression.

CONCLUSIONS

The SNPs in the ADAM17 promoter region do not appear to be major contributors to the pathogenesis of IS. However, the rs12692386 G ADAM17 allele is correlated with a higher expression of ADAM17 mRNA, which may play a role in increasing inflammation in IS patients. Furthermore, the ADAM17-rs1524668 polymorphism is linked to a higher risk of PACI-type stroke, confirming the role of ADAM17 in the pathophysiology of PACI, with potentially important therapeutic implications.