Collagens Regulating Adipose Tissue Formation and Functions

The effect of high-level dietary Laminaria digitata on the muscle proteome and metabolome of weaned piglets

The brown seaweed Laminaria digitata, known for its prebiotic qualities, and alginate lyase supplementation, may improve the growth and development of piglets during the critical post-weaning phase. The purpose of this study was to ascertain the effects of 10 % L. digitata and 0.01 % alginate lyase on the proteome and metabolome of the longissimus lumborum muscle in weaned piglets. Findings suggest that the enzyme supplement has a marginal effect on muscle proteome compared to the seaweed diet alone when compared to the control. L. digitata increased the prevalence of proteins related to muscle contraction and structure (such as ACTBL2), while it decreased the presence of glycolytic proteins (like GPI and ALDOC). It also increased the abundance of proteins related to the negative regulation of insulin receptor pathways, such as RABGAP1 and TSC2. Conversely, alginate lyase increased the abundance of proteins associated with fatty acid oxidation (ALOXE3) and calcium balance (WFS1), reflecting the impacts of dietary n-3 polyunsaturated fatty acids and lower calcium in the diet. As for the muscle metabolome, it remained mostly unchanged by dietary treatments, except for mannitol and threonine, which were enriched as a consequence of seaweed inclusion.

Fasciitis-panniculitis syndrome with autoantibodies reacting to adipocyte pericellular fibers: a case report

BACKGROUND

Fasciitis-panniculitis syndrome (FPS) typically presents with swelling and skin hardening. Its histopathological characteristics include inflammatory cell infiltration and fibrous thickening of the subcutaneous tissue and fascia. Panniculitides in children are rare and only a small number of juvenile FPS cases have been reported. We encountered a case of a 10-year-old boy in which autoantibodies reactive to adipocyte pericellular fibers were detected in relapsing FPS.

CASE PRESENTATION

The patient developed a high fever and skin swelling with pain and erythema on the right side of his body following an abrasion injury on his right wrist at the age of 5 years, and was suspected of having streptococcal toxic shock-like syndrome, for which he received antimicrobials, immunoglobulin therapy, debridement, and plasma exchange. The same manifestations with similar magnetic resonance imaging (MRI) findings of high signal on short tau inversion recovery showing the spread of inflammation in the fat tissue and fascia was observed twice at the age of 6 years. Serological analyses for conventional autoantibodies, bone marrow aspiration, and whole-exome sequencing examination were non-remarkable. Prednisolone was effective in ameliorating the above putative autoinflammatory syndrome. The patient was admitted at the age of 10 years with similar clinical and MRI findings indicative of recurrence of the same disease. En bloc biopsy from the skin to the fascia showed thickening of collagen fibers, infiltration of inflammatory cells composed mainly of neutrophils and lymphocytes, and necrotizing vasculitis in the fat tissue and fascia. Immunohistochemical staining of the en bloc biopsy sections indicated infiltration of T lymphocytes and macrophages in the perivascular connective tissue and fibrinoid necrosis, supporting the diagnosis of FPS. Induction therapy with prednisolone resulted in a remission. IgG purified from the patient's serum reacted with pericellular basement membranes in the subcutaneous fat tissue by immunohistochemistry. The patient is currently taking famotidine to prevent relapses and is making good progress in his recovery.

CONCLUSIONS

Although pathogenic autoantibodies have not been described in FPS, our results suggest that fat-tissue-reactive autoantibodies may be involved in the pathogenesis of FPS.

Obesity-induced mesenteric PVAT remodelling is sexually dimorphic, but not driven by ovarian hormones : Short title: Obesity induces sex-specific responses in mesenteric PVAT

BACKGROUND

Obesity, a major risk factor for cardiovascular disease (CVD), is associated with hypertension and vascular dysfunction. Perivascular adipose tissue (PVAT), a metabolically active tissue surrounding blood vessels, plays a key role in regulating vascular tone. In obesity, PVAT becomes dysregulated which may contribute to vascular dysfunction; how sex impacts the remodelling of PVAT and thus the altered vascular contractility during obesity is unclear.

OBJECTIVE

To investigate sex-specific PVAT dysregulation in the setting of obesity as a potential driver of sex differences in vascular pathologies and CVD risk.

METHODS

Adult male and female C57Bl/6J mice were fed an obesogenic high-fat diet (HFD) or regular chow for 16 weeks. Mesenteric PVAT (mPVAT) was isolated for RNA-sequencing and histological analysis, and mesenteric arteries were isolated for assessment of vascular function by wire myography. In a separate study, female mice were subjected to bilateral ovariectomy prior to dietary intervention to determine the contribution of ovarian hormones to PVAT dysregulation.

RESULTS

Transcriptomic analysis of mPVAT revealed sexually dimorphic responses to HFD, with upregulation of extracellular matrix (ECM) remodelling pathways in male but not female mice. Histological and RT-qPCR approaches demonstrated increased collagen deposition and ECM remodelling in mPVAT from obese male compared with obese female mice. Assessment of vascular function in mesenteric arteries -/+ PVAT revealed that in obesity, mPVAT impaired endothelium-mediated vasodilation in male but not female mice. Ovariectomy of female mice prior to HFD administration did not alter ECM transcript expression or collagen deposition in mPVAT compared to sham-operated female mice.

CONCLUSIONS

Obesity induces sex-specific molecular remodelling in mPVAT, with male mice exhibiting unique upregulation of ECM pathways and increased collagen deposition compared to females. Moreover, the relative protection of female mice from obesity-induced mPVAT dysregulation is not mediated by ovarian hormones. These data highlight a potential sex-specific mechanistic link between mPVAT and mesenteric artery dysfunction in obesity, and provides crucial insights for future development of treatment strategies that consider the unique cardiovascular risks in men and women.

Exploring genetic signatures of obesity: hub genes and miRNAs unveiled through comprehensive bioinformatic analysis

Objectives

Adipogenesis, the process of fat accumulation in adipose tissue, is closely linked to obesity, a condition characterized by excessive fat storage. Genetic factors significantly contribute to an individual's susceptibility to adipogenesis and the development of obesity.

Methods

In this study, we conducted a comprehensive bioinformatic analysis, including Weighted Gene Co-expression Analysis, differentially expressed gene analysis, and protein-protein interaction analysis, to identify hub genes and miRNAs associated with obesity.

Results

Our findings highlight the potential involvement of genes such as ATP5F1A, FN1, CCl2, RPS14, and RPS16, as well as miRNAs including hsa-miR-6844, hsa-miR-4528, hsa-miR-3686, hsa-miR-3124-3p, hsa-miR-381-3p, and hsa-miR-300 in obesity.

Conclusions

The findings from this study contribute to the growing knowledge of adipogenesis and obesity genetics, and provide potential biomarkers for further investigation and translation into clinical or research applications.

Graphical abstract

Supplementary Information

The online version contains supplementary material available at 10.1007/s40200-024-01490-8.

Single-cell DNA methylome and 3D genome atlas of the human subcutaneous adipose tissue

Human subcutaneous adipose tissue (SAT) contains a diverse array of cell-types; however, the epigenomic landscape among the SAT cell-types has remained elusive. Our integrative analysis of single-cell resolution DNA methylation and chromatin conformation profiles (snm3C-seq), coupled with matching RNA expression (snRNA-seq), systematically cataloged the epigenomic, 3D topology, and transcriptomic dynamics across the SAT cell-types. We discovered that the SAT CG methylation (mCG) landscape is characterized by pronounced hyper-methylation in myeloid cells and hypo-methylation in adipocytes and adipose stem and progenitor cells (ASPCs), driving nearly half of the 705,063 detected differentially methylated regions (DMRs). In addition to the enriched cell-type-specific transcription factor binding motifs, we identified TET1 and DNMT3A as plausible candidates for regulating cell-type level mCG profiles. Furthermore, we observed that global mCG profiles closely correspond to SAT lineage, which is also reflected in cell-type-specific chromosome compartmentalization. Adipocytes, in particular, display significantly more short-range chromosomal interactions, facilitating the formation of complex local 3D genomic structures that regulate downstream transcriptomic activity, including those associated with adipogenesis. Finally, we discovered that variants in cell-type level DMRs and A compartments significantly predict and are enriched for variance explained in abdominal obesity. Together, our multimodal study characterizes human SAT epigenomic landscape at the cell-type resolution and links partitioned polygenic risk of abdominal obesity to SAT epigenome.

Fascial Manual Medicine: A Continuous Evolution

From the perspective of fascial manual medicine (FMM), the body should not be considered as a set of compartments, but as a functional continuum, where most of the tissues (considering embryology) are fascia. The cells that make up the fascia can use multiple strategies to communicate, with neighboring cells, with the tissue to which they belong, and with the entire body, thanks to biochemical (microscopy) and electromagnetic (nanoscopy) possibilities. These multiple capacities to send and receive information make the border or layer of the different tissues seem absent. All the manual techniques that profess to be the only ones that work on the patient's symptoms, dictating a standardized manual procedure that all patients should undergo, represent a clinical deviation. Likewise, thinking that the manual approach can provide biomechanical stimuli only to a single specific structure or layer is a conceptual error. This narrative review briefly reviews the history of fascial-related nomenclature and how the fascial system is currently considered, posing new reflections on how the fascial continuum could be conceived by practitioners who apply FMM in the clinic, such as osteopaths, chiropractors, and physiotherapists.

Comprehensive Proteomic Profiling of Converted Adipocyte-like Cells from Normal Human Dermal Fibroblasts Using Data-Independent Acquisition Mass Spectrometry

Adipocytes play an important role in the regulation of systemic energy homeostasis and are closely related to metabolic disorders, such as type-2 diabetes and inflammatory bowel diseases. Particularly, there is an increasing need for a human adipocyte model for studying metabolic diseases and obesity. However, utilizing human primary adipocyte culture and stem-cell-based models presents several practical limitations due to their time-consuming nature, requirement for relatively intensive labor, and high cost. Here, we applied direct conversion of normal human dermal fibroblasts (NHDFs) into adipocyte-like cells using an adipogenic cocktail containing 3-isobutyl-1-methylxanthine (IBMX), dexamethasone, insulin, and rosiglitazone and confirmed prominent lipid droplet accumulation in the converted cells. For profiling the proteome changes in the converted cells, we conducted a comprehensive quantitative proteome analysis of both the intracellular and extracellular proteome fractions using data-independent acquisition mass spectrometry. We observed that several proteins, which are known to be highly expressed in adipocytes specifically, were dominantly increased in the converted cells. In this study, we suggest that NHDFs can be converted into adipocyte-like cells by an adipogenic cocktail and can serve as a useful tool for studying human adipocytes and their metabolism.

Obesity Induces Temporally Regulated Alterations in the Extracellular Matrix That Drive Breast Tumor Invasion and Metastasis

Obesity is associated with increased incidence and metastasis of triple-negative breast cancer, an aggressive breast cancer subtype. The extracellular matrix (ECM) is a major component of the tumor microenvironment that drives metastasis. To characterize the temporal effects of age and high-fat diet (HFD)-driven weight gain on the ECM, we injected allograft tumor cells at 4-week intervals into mammary fat pads of mice fed a control or HFD, assessing tumor growth and metastasis and evaluating the ECM composition of the mammary fat pads, lungs, and livers. Tumor growth was increased in obese mice after 12 weeks on HFD. Liver metastasis increased in obese mice only at 4 weeks, and elevated body weight correlated with increased metastasis to the lungs but not the liver. Whole decellularized ECM coupled with proteomics indicated that early stages of obesity were sufficient to induce changes in the ECM composition. Obesity led to an increased abundance of the proinvasive ECM proteins collagen IV and collagen VI in the mammary glands and enhanced the invasive capacity of cancer cells. Cells of stromal vascular fraction and adipose stem and progenitor cells were primarily responsible for secreting collagen IV and collagen VI, not adipocytes. Longer exposure to HFD increased the invasive potential of ECM isolated from the lungs and liver, with significant changes in ECM composition found in the liver with short-term HFD exposure. Together, these data suggest that changes in the breast, lungs, and liver ECM underlie some of the effects of obesity on triple-negative breast cancer incidence and metastasis. Significance: Organ-specific extracellular matrix changes in the primary tumor and metastatic microenvironment are mechanisms by which obesity contributes to breast cancer progression.

Insulin-Independent Regulation of Type 1 Diabetes via Brown Adipocyte-Secreted Proteins and the Novel Glucagon Regulator Nidogen-2

Current treatments for type 1 diabetes (T1D) focus on insulin replacement. We demonstrate the therapeutic potential of a secreted protein fraction from embryonic brown adipose tissue (BAT), independent of insulin. The large molecular weight secreted fraction mediates insulin receptor-dependent recovery of euglycemia in a T1D animal model, nonobese diabetic (NOD) mice, by suppressing glucagon secretion. This fraction also promotes white adipocyte differentiation and browning, maintains healthy BAT, and enhances glucose uptake in adipose tissue, skeletal muscle, and liver. From this fraction, we identify nidogen-2 as a critical BAT-secreted protein that reverses hyperglycemia in NOD mice, inhibits glucagon secretion from pancreatic α-cells, and mimics other actions of the entire secreted fraction. These findings confirm that BAT transplants affect physiology and demonstrate that BAT-secreted peptides represent a novel therapeutic approach to diabetes management. Furthermore, our research reveals a novel signaling role for nidogen-2, beyond its traditional classification as an extracellular matrix protein.

HIGHLIGHTS

The large molecular weight brown adipocyte-secreted protein fraction suppresses glucagon secretion and normalizes glycemia in mouse models of type 1 diabetes (T1D), independent of insulin, offering a novel therapeutic strategy for disease management.Nidogen-2, a critical component of this fraction, is identified as an inhibitor of glucagon secretion in pancreatic α-cells by regulating intracellular messenger activities.The large-secreted protein fraction prevents T1D-related whitening of brown adipose tissue, promotes adipocyte differentiation, and enhances browning of inguinal white adipose tissue.This fraction enhances glucose uptake in adipose tissue, skeletal muscle, and liver through an insulin receptor-dependent pathway.

Skeletal muscle BMAL1 is necessary for transcriptional adaptation of local and peripheral tissues in response to endurance exercise training

OBJECTIVE

In this investigation, we addressed the contribution of the core circadian clock factor, BMAL1, in skeletal muscle to both acute transcriptional responses to exercise and transcriptional remodeling in response to exercise training. Additionally, we adopted a systems biology approach to investigate how loss of skeletal muscle BMAL1 altered peripheral tissue homeostasis as well as exercise training adaptations in iWAT, liver, heart, and lung of male mice.

METHODS

Combining inducible skeletal muscle specific BMAL1 knockout mice, physiological testing and standardized exercise protocols, we performed a multi-omic analysis (transcriptomics, chromatin accessibility and metabolomics) to explore loss of muscle BMAL1 on muscle and peripheral tissue responses to exercise.

RESULTS

Muscle-specific BMAL1 knockout mice demonstrated a blunted transcriptional response to acute exercise, characterized by the lack of upregulation of well-established exercise responsive transcription factors including Nr4a3 and Ppargc1a. Six weeks of exercise training in muscle-specific BMAL1 knockout mice induced significantly greater and divergent transcriptomic and metabolomic changes in muscle. Surprisingly, liver, lung, inguinal white adipose and heart showed divergent exercise training transcriptomes with less than 5% of 'exercise-training' responsive genes shared for each tissue between genotypes.

CONCLUSIONS

Our investigation has uncovered the critical role that BMAL1 plays in skeletal muscle as a key regulator of gene expression programs for both acute exercise and training adaptations. In addition, our work has uncovered the significant impact that altered exercise response in muscle and its likely impact on the system plays in the peripheral tissue adaptations to exercise training. Our work also demonstrates that if the muscle adaptations diverge to a more maladaptive state this is linked to increased gene expression signatures of inflammation across many tissues. Understanding the molecular targets and pathways contributing to health vs. maladaptive exercise adaptations will be critical for the next stage of therapeutic design for exercise mimetics.

Role of Na/K-ATPase α1 caveolin-binding motif in adipogenesis

Deficiencies in mice and in humans have brought to the fore the importance of the caveolar network in key aspects of adipocyte biology. The conserved N-terminal caveolin-binding motif (CBM) of the ubiquitous Na/K-ATPase (NKA) α1 isoform, which allows NKA/caveolin-1 (Cav1) interaction, influences NKA signaling and caveolar distribution. It has been shown to be critical for animal development and ontogenesis, as well as lineage-specific differentiation of human induced pluripotent stem cells (hiPSCs). However, its role in postnatal adipogenesis has not been fully examined. Using a genetic approach to alter CBM in hiPSC-derived adipocytes (iAdi-mCBM) and in mice (mCBM), we investigated the regulatory function of NKA CBM signaling in adipogenesis. Seahorse XF cell metabolism analyses revealed impaired glycolysis and decreased ATP synthesis-coupled respiration in iAdi-mCBM. These metabolic dysfunctions were accompanied by evidence of extensive remodeling of the extracellular matrix (ECM), including increased collagen staining, overexpression of ECM marker genes, and heightened TGF-β signaling uncovered by RNAseq analysis. Rescue of mCBM by lentiviral delivery of WT NKA α1 or treatment of mCBM hiPSCs with the TGF-β inhibitor SB431542 normalized ECM, suggesting that NKA CBM signaling integrity is required for adequate control of TGF-β signaling and ECM stiffness during adipogenesis. The physiological impact was revealed in mCBM male mice with reduced fat mass accompanied by histological and transcriptional evidence of elevated adipose fibrosis and decreased adipocyte size. Based on these findings, we propose that the genetic alteration of the NKA/Cav1 regulatory path uncovered in human iAdi leads to lipodystrophy in mice.NEW & NOTEWORTHY A Na/K-ATPase α1 caveolin-binding motif regulates adipogenesis. Mutation of this binding motif in the mouse leads to reduced fat with increased extracellular matrix production and inflammation. RNA-seq analysis and pharmacological interventions in human iPSC-derived adipocytes revealed that TGF-β signal, rather than Na/K-ATPase-mediated ion transport, is a key mediator of NKA regulation of adipogenesis.

Employing machine learning for enhanced abdominal fat prediction in cavitation post-treatment

This study investigates the application of cavitation in non-invasive abdominal fat reduction and body contouring, a topic of considerable interest in the medical and aesthetic fields. We explore the potential of cavitation to alter abdominal fat composition and delve into the optimization of fat prediction models using advanced hyperparameter optimization techniques, Hyperopt and Optuna. Our objective is to enhance the predictive accuracy of abdominal fat dynamics post-cavitation treatment. Employing a robust dataset with abdominal fat measurements and cavitation treatment parameters, we evaluate the efficacy of our approach through regression analysis. The performance of Hyperopt and Optuna regression models is assessed using metrics such as mean squared error, mean absolute error, and R-squared score. Our results reveal that both models exhibit strong predictive capabilities, with R-squared scores reaching 94.12% and 94.11% for post-treatment visceral fat, and 71.15% and 70.48% for post-treatment subcutaneous fat predictions, respectively. Additionally, we investigate feature selection techniques to pinpoint critical predictors within the fat prediction models. Techniques including F-value selection, mutual information, recursive feature elimination with logistic regression and random forests, variance thresholding, and feature importance evaluation are utilized. The analysis identifies key features such as BMI, waist circumference, and pretreatment fat levels as significant predictors of post-treatment fat outcomes. Our findings underscore the effectiveness of hyperparameter optimization in refining fat prediction models and offer valuable insights for the advancement of non-invasive fat reduction methods. This research holds important implications for both the scientific community and clinical practitioners, paving the way for improved treatment strategies in the realm of body contouring.

Unraveling the rationale and conducting a comprehensive assessment of KD025 (Belumosudil) as a candidate drug for inhibiting adipogenic differentiation-a systematic review

Rho-associated kinases (ROCKs) are crucial during the adipocyte differentiation process. KD025 (Belumosudil) is a newly developed inhibitor that selectively targets ROCK2. It has exhibited consistent efficacy in impeding adipogenesis across a spectrum of in vitro models of adipogenic differentiation. Given the novelty of this treatment, a comprehensive systematic review has not been conducted yet. This systematic review aims to fill this knowledge void by providing readers with an extensive examination of the rationale behind KD025 and its impacts on adipogenesis. Preclinical evidence was gathered owing to the absence of clinical trials. The Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines were followed, and the study's quality was assessed using the Joanna Briggs Institute (JBI) Checklist Critical Appraisal Tool for Systematic Reviews. In various in vitro models, such as 3T3-L1 cells, human orbital fibroblasts, and human adipose-derived stem cells, KD025 demonstrated potent anti-adipogenic actions. At a molecular level, KD025 had significant effects, including decreasing fibronectin (Fn) expression, inhibiting ROCK2 and CK2 activity, suppressing lipid droplet formation, and reducing the expression of proadipogenic genes peroxisome proliferator-activated receptor gamma (PPARγ) and CCAAT/enhancer-binding protein α (C/EBPα). Additionally, KD025 resulted in the suppression of fatty acid-binding protein 4 (FABP4 or AP2) expression, a decrease in sterol regulatory element binding protein 1c (SREBP-1c) and Glut-4 expression. Emphasis must be placed on the fact that while KD025 shows potential in preclinical studies and experimental models, extensive research is crucial to assess its efficacy, safety, and potential therapeutic applications thoroughly and directly in human subjects.

Silencing ANGPTL8 reduces mouse preadipocyte differentiation and insulin signaling

ANGPTL8, expressed mainly in the liver and adipose tissue, regulates the activity of lipoprotein lipase (LPL) present in the extracellular space and triglyceride (TG) metabolism through its interaction with ANGPTL3 and ANGPTL4. Whether intracellular ANGPTL8 can also exert effects in tissues where it is expressed is uncertain. ANGPTL8 expression was low in preadipocytes and much increased during differentiation. To better understand the role of intracellular ANGPTL8 in adipocytes and assess whether it may play a role in adipocyte differentiation, we knocked down its expression in normal mouse subcutaneous preadipocytes. ANGPTL8 knockdown reduced adipocyte differentiation, cellular TG accumulation and also isoproterenol-stimulated lipolysis at day 7 of differentiation. RNA-Seq analysis of ANGPTL8 siRNA or control siRNA transfected SC preadipocytes on days 0, 2, 4 and 7 of differentiation showed that ANGPTL8 knockdown impeded the early (day 2) expression of adipogenic and insulin signaling genes, PPARγ, as well as genes related to extracellular matrix and NF-κB signaling. Insulin mediated Akt phosphorylation was reduced at an early stage during adipocyte differentiation. This study based on normal primary cells shows that ANGPTL8 has intracellular actions in addition to effects in the extracellular space, like modulating LPL activity. Preadipocyte ANGPTL8 expression modulates their differentiation possibly via changes in insulin signaling gene expression.

Matrix density regulates adipocyte phenotype

Alterations of the extracellular matrix contribute to adipose tissue dysfunction in metabolic disease. We studied the role of matrix density in regulating human adipocyte phenotype in a tunable hydrogel culture system. Lipid accumulation was maximal in intermediate hydrogel density of 5 weight %, relative to 3% and 10%. Adipogenesis and lipid and oxidative metabolic gene pathways were enriched in adipocytes in 5% relative to 3% hydrogels, while fibrotic gene pathways were enriched in 3% hydrogels. These data demonstrate that the intermediate density matrix promotes a more adipogenic, less fibrotic adipocyte phenotype geared towards increased lipid and aerobic metabolism. These observations contribute to a growing literature describing the role of matrix density in regulating adipose tissue function.

Age and obesity-driven changes in the extracellular matrix of the primary tumor and metastatic site influence tumor invasion and metastatic outgrowth

Younger age and obesity increase the incidence and metastasis of triple-negative breast cancer (TNBC), an aggressive subtype of breast cancer. The extracellular matrix (ECM) promotes tumor invasion and metastasis. We characterized the effect of age and obesity on the ECM of mammary fat pads, lungs, and liver using a diet-induced obesity (DIO) model. At 4 week intervals, we either injected the mammary fat pads with allograft tumor cells to characterize tumor growth and metastasis or isolated the mammary fat pads and livers to characterize the ECM. Age had no effect on tumor growth but increased lung and liver metastasis after 16 weeks. Obesity increased tumor growth starting at 12 weeks, increased liver metastasis only at 4 weeks, and weight gain correlated to increased lung but not liver metastasis. Utilizing whole decellularized ECM coupled with proteomics, we found that early stages of obesity were sufficient to induce changes in the ECM composition and invasive potential of mammary fat pads with increased abundance of pro-invasive ECM proteins Collagen IV and Collagen VI. We identified cells of stromal vascular fraction and adipose stem and progenitor cells as primarily responsible for secreting Collagen IV and VI, not adipocytes. We characterized the changes in ECM in the lungs and liver, and determined that older age decreases the metastatic potential of lung and liver ECM while later-stage obesity increases the metastatic potential. These data implicate ECM changes in the primary tumor and metastatic microenvironment as mechanisms by which age and obesity contribute to breast cancer progression.

Extracellular Matrix Expression in Human Pancreatic Fat Cells of Patients with Normal Glucose Regulation, Prediabetes and Type 2 Diabetes

Previously, we found that human pancreatic preadipocytes (PPAs) and islets influence each other and that the crosstalk with the fatty liver via the hepatokine fetuin-A/palmitate induces inflammatory responses. Here, we examined whether the mRNA-expression of pancreatic extracellular matrix (ECM)-forming and -degrading components differ in PPAs from individuals with normal glucose regulation (PPAs-NGR), prediabetes (PPAs-PD), and type 2 diabetes (PPAs-T2D), and whether fetuin-A/palmitate impacts ECM-formation/degradation and associated monocyte invasion. Human pancreatic resections were analyzed (immuno)histologically. PPAs were studied for mRNA expression by real-time PCR and protein secretion by Luminex analysis. Furthermore, co-cultures with human islets and monocyte migration assays in Transwell plates were conducted. We found that in comparison with NGR-PPAs, TIMP-2 mRNA levels were lower in PPAs-PD, and TGF-β1 mRNA levels were higher in PPAs-T2D. Fetuin-A/palmitate reduced fibronectin, decorin, TIMP-1/-2 and TGF-ß1 mRNA levels. Only fibronectin was strongly downregulated by fetuin-A/palmitate independently of the glycemic status. Co-culturing of PPAs with islets increased TIMP-1 mRNA expression in islets. Fetuin-A/palmitate increased MMP-1, usherin and dermatopontin mRNA-levels in co-cultured islets. A transmigration assay showed increased monocyte migration towards PPAs, which was enhanced by fetuin-A/palmitate. This was more pronounced in PPAs-T2D. The expression of distinct ECM components differs in PPAs-PD and PPAs-T2D compared to PPAs-NGR, suggesting that ECM alterations can occur even in mild hyperglycemia. Fetuin-A/palmitate impacts on ECM formation/degradation in PPAs and co-cultured islets. Fetuin-A/palmitate also enhances monocyte migration, a process which might impact on matrix turnover.

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.