Interferon tau alleviates obesity-induced adipose tissue inflammation and insulin resistance by regulating macrophage polarization

Interferon-tau protects bovine endometrial epithelial cells against inflammatory injury by regulating the PI3K/AKT/β-catenin/FoxO1 signaling axis

Endometritis is one of the most common causes of infertility in dairy cows, and is histopathologically characterized by inflammation and damage of endometrial epithelium. Interferon-tau (IFN-τ) is a novel type I interferon secreted by ruminant trophoblast cells with low cytotoxicity even at high doses. Previous studies suggested that IFN-τ plays an important role in inflammation. However, the mechanisms whereby IFN-τ may modulate the inflammatory responses in the bovine endometrium are unknown. In the present study, primary bovine endometrial epithelial cells (BEEC) isolated from fresh and healthy uterine horns were used for in vitro studies. The integrity of BEEC was assessed by immunofluorescence staining for cytokeratin 18 (CK-18, a known epithelial marker). For the experiments, BEEC were stimulated with different concentrations of lipopolysaccharide (LPS; 0-20 µg/mL) for different times (0-24 h). Cell viability and apoptosis were assessed via CCK-8 and flow cytometry. In a preliminary study, we observed that compared with the control group without LPS, 10 µg/mL of LPS stimulation for 24 h induced apoptosis. In a subsequent study, 20 or 40 ng/mL of IFN-τ alleviated LPS-induced apoptosis. Relative to the LPS group, western blotting further revealed that IFN-τ inhibited the protein abundance of TLR4 and phosphorylated (p-) p65 (p-p65) and Bax/Bcl-2 ratio, suggesting that IFN-τ can protect BEEC against inflammatory injury. Furthermore, the protein abundance of p-phosphoinositide 3-kinase (p-PI3K), p-protein kinase B (p-AKT), p-glycogen synthase kinase-3β (p-GSK3β), β-catenin, and p-forkhead box O1 (p-FoxO1) was lower in the LPS group, whereas IFN-τ upregulated their abundance. The use of LY294002, a specific inhibitor of PI3K/AKT, attenuated the upregulation of p-PI3K, p-AKT p-GSK3β, β-catenin, and p-FoxO1 induced by IFN-τ, and also blocked the downregulation of TLR4, p-p65, and Bax/Bcl-2 ratio. This suggested that the inhibition of TLR4 signaling by IFN-τ was mediated by the PI3K/AKT pathway. Furthermore, compared with the LPS group, the β-catenin agonist SB216763 led to greater p-FoxO1 and lower p-p65 and cell apoptosis. In contrast, knockdown of β-catenin using small interfering RNA had the opposite effects. To explore the role of FoxO1 on the inhibition of TLR4 by IFN-τ, we employed LY294002 to inhibit the PI3K/AKT while FoxO1 was knocked down. Results revealed that the knockdown of FoxO1 blocked the upregulation of TLR4 and p-p65 induced by LY294002, and enhanced the inhibition of IFN-τ on TLR4, p-p65, and cell apoptosis. Overall, these findings confirmed that IFN-τ can protect endometrial epithelial cells against inflammatory injury via suppressing TLR4 activation through the regulation of the PI3K/AKT/β-catenin/FoxO1 axis. These represent new insights into the molecular mechanisms underlying the anti-inflammatory function of IFN-τ in BEEC, and also provide a theoretical basis for further studies on the in vivo application of IFN-τ to help prevent negative effects of endometritis.

Dysregulated systemic metabolism in a Down syndrome mouse model

OBJECTIVE

Trisomy 21 is one of the most complex genetic perturbations compatible with postnatal survival. Dosage imbalance arising from the triplication of genes on human chromosome 21 (Hsa21) affects multiple organ systems. Much of Down syndrome (DS) research, however, has focused on addressing how aneuploidy dysregulates CNS function leading to cognitive deficit. Although obesity, diabetes, and associated sequelae such as fatty liver and dyslipidemia are well documented in the DS population, only limited studies have been conducted to determine how gene dosage imbalance affects whole-body metabolism. Here, we conduct a comprehensive and systematic analysis of key metabolic parameters across different physiological states in the Ts65Dn trisomic mouse model of DS.

METHODS

Ts65Dn mice and euploid littermates were subjected to comprehensive metabolic phenotyping under basal (chow-fed) state and the pathophysiological state of obesity induced by a high-fat diet (HFD). RNA sequencing of liver, skeletal muscle, and two major fat depots were conducted to determine the impact of aneuploidy on tissue transcriptome. Pathway enrichments, gene-centrality, and key driver estimates were performed to provide insights into tissue autonomous and non-autonomous mechanisms contributing to the dysregulation of systemic metabolism.

RESULTS

Under the basal state, chow-fed Ts65Dn mice of both sexes had elevated locomotor activity and energy expenditure, reduced fasting serum cholesterol levels, and mild glucose intolerance. Sexually dimorphic deterioration in metabolic homeostasis became apparent when mice were challenged with a high-fat diet. While obese Ts65Dn mice of both sexes exhibited dyslipidemia, male mice also showed impaired systemic insulin sensitivity, reduced mitochondrial activity, and elevated fibrotic and inflammatory gene signatures in the liver and adipose tissue. Systems-level analysis highlighted conserved pathways and potential endocrine drivers of adipose-liver crosstalk that contribute to dysregulated glucose and lipid metabolism.

CONCLUSIONS

A combined alteration in the expression of trisomic and disomic genes in peripheral tissues contribute to metabolic dysregulations in Ts65Dn mice. These data lay the groundwork for understanding the impact of aneuploidy on in vivo metabolism.

Interferon Family Cytokines in Obesity and Insulin Sensitivity

Obesity and its associated complications are global public health concerns. Metabolic disturbances and immune dysregulation cause adipose tissue stress and dysfunction in obese individuals. Immune cell accumulation in the adipose microenvironment is the main cause of insulin resistance and metabolic dysfunction. Infiltrated immune cells, adipocytes, and stromal cells are all involved in the production of proinflammatory cytokines and chemokines in adipose tissues and affect systemic homeostasis. Interferons (IFNs) are a large family of pleiotropic cytokines that play a pivotal role in host antiviral defenses. IFNs are critical immune modulators in response to pathogens, dead cells, and several inflammation-mediated diseases. Several studies have indicated that IFNs are involved in the pathogenesis of obesity. In this review, we discuss the roles of IFN family cytokines in the development of obesity-induced inflammation and insulin resistance.

Anti-inflammatory agents as modulators of the inflammation in adipose tissue: A systematic review

Obesity is characterized by an adipose tissue mass expansion that presents a risk to health, associated with a chronic increase in circulating inflammatory mediators. Anti-inflammatory agents are an obesity alternative treatment. However, the lack of effective agents indicates the need to assess the mechanisms and identify effective therapeutic targets. The present work identified and described the mechanisms of action of anti-inflammatory agents in adipose tissue in experimental studies. The review was registered in the International Prospective Registry of Systematic Reviews (PROSPERO-CRD42020182897). The articles' selection was according to eligibility criteria (PICOS). The research was performed in PubMed, ScienceDirect, Scopus, Web of Science, VHL, and EMBASE. The methodological quality evaluation was assessed using SYRCLE. Initially, 1511 articles were selected, and at the end of the assessment, 41 were eligible. Among the anti-inflammatory agent classes, eight drugs, 28 natural, and five synthetic compounds were identified. Many of these anti-inflammatory agents act in metabolic pathways that culminate in the inflammatory cytokines expression reduction, decreasing the macrophages infiltration in white and adipose tissue and promoting the polarization process of type M1 to M2 macrophages. Thus, the article clarifies and systematizes these anti-inflammatory agents' mechanisms in adipose tissue, presenting targets relevant to future research on these pathways.

Findings from Studies Are Congruent with Obesity Having a Viral Origin, but What about Obesity-Related NAFLD?

Infection has recently started receiving greater attention as an unusual causative/inducing factor of obesity. Indeed, the biological plausibility of infectobesity includes direct roles of some viruses to reprogram host metabolism toward a more lipogenic and adipogenic status. Furthermore, the probability that humans may exchange microbiota components (virome/virobiota) points out that the altered response of IFN and other cytokines, which surfaces as a central mechanism for adipogenesis and obesity-associated immune suppression, is due to the fact that gut microbiota uphold intrinsic IFN signaling. Last but not least, the adaptation of both host immune and metabolic system under persistent viral infections play a central role in these phenomena. We hereby discuss the possible link between adenovirus and obesity-related nonalcoholic fatty liver disease (NAFLD). The mechanisms of adenovirus-36 (Ad-36) involvement in hepatic steatosis/NAFLD consist in reducing leptin gene expression and insulin sensitivity, augmenting glucose uptake, activating the lipogenic and pro-inflammatory pathways in adipose tissue, and increasing the level of macrophage chemoattractant protein-1, all of these ultimately leading to chronic inflammation and altered lipid metabolism. Moreover, by reducing leptin expression and secretion Ad-36 may have in turn an obesogenic effect through increased food intake or decreased energy expenditure via altered fat metabolism. Finally, Ad-36 is involved in upregulation of cAMP, phosphatidylinositol 3-kinase, and p38 signaling pathways, downregulation of Wnt10b expression, increased expression of CCAAT/enhancer binding protein-beta, and peroxisome proliferator-activated receptor gamma 2 with consequential lipid accumulation.

Type I Interferons as Joint Regulators of Tumor Growth and Obesity

Simple Summary

The escalating global epidemic of overweight and obesity is a major public health and economic problem, as excess body weight represents a significant risk factor for several chronic diseases including cancer. Despite the strong scientific evidence for a link between obesity and cancer, the mechanisms involved in this interplay have not yet been fully understood. The aim of this review is to evaluate the role of type I interferons, a family of antiviral cytokines with key roles in the regulation of both obesity and cancer, highlighting how the dysregulation of the interferon system can differently affect these pathological conditions.

Abstract

Type I interferons (IFN-I) are antiviral cytokines endowed with multiple biological actions, including antitumor activity. Studies in mouse models and cancer patients support the concept that endogenous IFN-I play important roles in the control of tumor development and growth as well as in response to several chemotherapy/radiotherapy treatments. While IFN-I signatures in the tumor microenvironment are often considered as biomarkers for a good prognostic response to antitumor therapies, prolonged IFN-I signaling can lead to immune dysfunction, thereby promoting pathogen or tumor persistence, thus revealing the “Janus face” of these cytokines in cancer control, likely depending on timing, tissue microenvironment and cumulative levels of IFN-I signals. Likewise, IFN-I exhibit different and even opposite effects on obesity, a pathologic condition linked to cancer development and growth. As an example, evidence obtained in mouse models shows that localized expression of IFN-I in the adipose tissue results in inhibition of diet–induced obesity, while hyper-production of these cytokines by specialized cells such as plasmacytoid dendritic cells in the same tissue, can induce systemic inflammatory responses leading to obesity. Further studies in mouse models and humans should reveal the mechanisms by which IFN-I can regulate both tumor growth and obesity and to understand the role of factors such as genetic background, diet and microbioma in shaping the production and action of these cytokines under physiological and pathological conditions.

Viral Infections and Interferons in the Development of Obesity

Obesity is now a prevalent disease worldwide and has a multi-factorial etiology. Several viruses or virus-like agents including members of adenoviridae, herpesviridae, slow virus (prion), and hepatitides, have been associated with obesity; meanwhile obese patients are shown to be more susceptible to viral infections such as during influenza and dengue epidemics. We examined the co-factorial role of viral infections, particularly of the persistent cases, in synergy with high-fat diet in induction of obesity. Antiviral interferons (IFNs), as key immune regulators against viral infections and in autoimmunity, emerge to be a pivotal player in the regulation of adipogenesis. In this review, we examine the recent evidence indicating that gut microbiota uphold intrinsic IFN signaling, which is extensively involved in the regulation of lipid metabolism. However, the prolonged IFN responses during persistent viral infections and obesogenesis comprise reciprocal causality between virus susceptibility and obesity. Furthermore, some IFN subtypes have shown therapeutic potency in their anti-inflammation and anti-obesity activity.

Micro-environment and intracellular metabolism modulation of adipose tissue macrophage polarization in relation to chronic inflammatory diseases

The accumulation and pro-inflammatory polarization of immune cells, mainly macrophages, in adipose tissue (AT) are considered crucial factors for obesity-induced chronic inflammatory diseases. In this review, we highlighted the role of adipose tissue macrophage (ATM) polarization on AT function in the obese state and the effect of the micro-environment and intracellular metabolism on the dynamic switch of ATMs into their pro-inflammatory or anti-inflammatory phenotypes, which may have distinct influences on obesity-related chronic inflammatory diseases. Obesity-associated metabolic dysfunctions, including those of glucose, fatty acid, cholesterol, and other nutrient substrates such as vitamin D and iron in AT, promote the pro-inflammatory polarization of ATMs and AT inflammation via regulating the interaction between ATMs and adipocytes and intracellular metabolic pathways, including glycolysis, fatty acid oxidation, and reverse cholesterol transportation. Focusing on the regulation of ATM metabolism will provide a novel target for the treatment of obesity-related chronic inflammatory diseases, including insulin resistance, cardiovascular diseases, and cancers.

Protective Effects of Interferon-tau Against Lipopolysaccharide-Induced Embryo Implantation Failure in Pregnant Mice

Interferon-tau (IFN-τ), a novel type I interferon, is produced by trophoblast cells in ruminants. Previous studies have confirmed that IFN-τ could induce immunological tolerance in humans and other species. However, there are few reports on whether IFN-τ has a protective effect on embryo implantation failure caused by excessive inflammation at the maternal-fetal interface. In our study, a mouse model of lipopolysaccharide (LPS)-induced implantation failure was successfully established, and we investigated the protective effects of IFN-τ. First, we showed that IFN-τ increased the number of implanted embryos in LPS-treated pregnant mice. Subsequently, quantitative real-time polymerase chain reaction (qPCR) and ELISA results showed that several inflammatory cytokines [IL-1β and tumor necrosis factor-alpha (TNF-α)] whose expression was upregulated by LPS were reversed by IFN-τ treatment. Furthermore, we performed Western blotting and found that IFN-τ restrained the LPS-induced phosphorylation of IκBα and NF-κB p65. Moreover, qPCR and immunohistochemistry analyses showed that IFN-τ decreased the LPS-induced expression of mouse major histocompatibility complex (MHC) class I genes (H-2K and H-2D) in LPS-treated pregnant mice. Taken together, these results suggest that IFN-τ has a protective effect in LPS-induced implantation failure by downregulating MHC class I genes expression and inhibiting the production of inflammatory cytokines.

Macrophage polarization and meta-inflammation

Chronic overnutrition and obesity induces low-grade inflammation throughout the body. Termed "meta-inflammation," this chronic state of inflammation is mediated by macrophages located within the colon, liver, muscle, and adipose tissue. A sentinel orchestrator of immune activity and homeostasis, macrophages adopt variable states of activation as a function of time and environmental cues. Meta-inflammation phenotypically skews these polarization states and has been linked to numerous metabolic disorders. The past decade has revealed several key regulators of macrophage polarization, including the signal transducer and activator of transcription family, the peroxisome proliferator-activated receptor gamma, the CCAAT-enhancer-binding proteins (C/EBP) family, and the interferon regulatory factors. Recent studies have also suggested that microRNAs and long noncoding RNA influence macrophage polarization. The pathogenic alteration of macrophage polarization in meta-inflammation is regulated by both extracellular and intracellular cues, resulting in distinct secretome profiles. Meta-inflammation-altered macrophage polarization has been linked to insulin insensitivity, atherosclerosis, inflammatory bowel disease, cancer, and autoimmunity. Thus, further mechanistic exploration into the skewing of macrophage polarization promises to have profound impacts on improving global health.

Chronicling the discovery of interferon tau

It has been 38 years since a protein, now known as interferon tau (IFNT), was discovered in ovine conceptus-conditioned culture medium. After 1979, purification and testing of native IFNT revealed its unique antiluteolyic activity to prevent the regression of corpora lutea on ovaries of nonpregnant ewes. Antiviral, antiproliferative and immunomodulatory properties of native and recombinant IFNT were demonstrated later. In addition, progesterone and IFNT were found to act cooperatively to silence expression of classical interferon stimulated genes in a cell-specific manner in ovine uterine luminal and superficial glandular epithelia. But, IFNT signaling through a STAT1/STAT2-independent pathway stimulates expression of genes, such as those for transport of glucose and amino acids, which are required for growth and development of the conceptus. Further, undefined mechanisms of action of IFNT are key to a servomechanism that allows ovine placental lactogen and placental growth hormone to affect the development of uterine glands and their expression of genes throughout gestation. IFNT also acts systemically to induce the expression of interferon stimulated genes that influence secretion of progesterone by the corpus luteum. Finally, IFNT has great potential as a therapeutic agent due to its low cytotoxicity, anti-inflammatory properties and effects to mitigate diabetes, obesity-associated syndromes and various autoimmune diseases.

The Effects of Metformin on Obesity-Induced Dysfunctional Retinas

Purpose

The purpose of this study was to determine the effects of metformin on dysfunctional retinas in obesity-induced type 2 diabetic mice.

Methods

A high-fat diet (HFD)-induced diabetic mouse model (C57BL/6J) was used in this study. After 2 months of the HFD regimen, HFD mice were given daily metformin through oral gavage. Body weights, glucose tolerance, and retinal light responses were monitored regularly. Fluorescein angiography (FA) was used to assess changes in retinal vasculature. Ocular tissues (retina, vitreous, and lens) were harvested and analyzed for molecular changes as determined by immunofluorescent staining, Western blot analysis, and cytokine profiling.

Results

Starting 1 month after the diet regimen, mice fed the HFD had mildly compromised retinal light responses as measured by electroretinography (ERG), which worsened over time compared to that in the control. In HFD mice treated with metformin, systemic glucose levels reverted back to normal, and their weight gain slowed. Metformin reversed HFD-induced changes in phosphorylated protein kinase B (pAKT), extracellular signal-regulated kinase (pERK), and 5′AMP-activated protein kinase (pAMPK) in the retina. However, metformin treatments for 3 months did not restore the retinal light responses nor lessen the HFD-induced retinal neovascularization, even though it did reduce intraocular inflammation.

Conclusions

Although metformin was able to reverse systemic changes induced by HFD, it was not able to restore HFD-caused retinal light responses or deter neovascularization.

IFN-τ Alleviates Lipopolysaccharide-Induced Inflammation by Suppressing NF-κB and MAPKs Pathway Activation in Mice

IFN-τ, which is a type I interferon with low cytotoxicity, is defined as a pregnancy recognition signal in ruminants. Type I interferons have been used as anti-inflammatory agents, but their side effects limit their clinical application. The present study aimed to determine the anti-inflammatory effects of IFN-τ in a lipopolysaccharide-stimulated acute lung injury (ALI) model and in RAW264.7 cells and to confirm the mechanism of action involved. The methods used included histopathology, measuring the lung wet/dry ratio, determining the myeloperoxidase activity, ELISA, qPCR, and western blot. The results revealed that IFN-τ greatly ameliorated the infiltration of inflammatory cells and the expression of TNF-α, IL-1β, and IL-6. Further analysis revealed that IFN-τ down-regulated the expression of TLR-2 and TLR-4 mRNA and the activity of the NF-κB and MAPK pathways both in a lipopolysaccharide-induced ALI model and in RAW264.7 cells. The results demonstrated that IFN-τ suppressed the levels of pro-inflammatory cytokines by inhibiting the phosphorylation of the NF-κB and MAPK pathways. Thus, IFN-τ may be an optimal target for the treatment of inflammatory diseases.

Butein induction of HO-1 by p38 MAPK/Nrf2 pathway in adipocytes attenuates high-fat diet induced adipose hypertrophy in mice

Adipose tissue inflammation and oxidative stress are key components in the development of obesity and insulin resistance. Heme oxygenase (HO)-1 in adipocytes protects against obesity and adipose dysfunction. In this study, we report the identification of butein, a flavonoid chalcone, as a novel inducer of HO-1 expression in adipocytes in vitro and in vivo. Butein upregulated HO-1 mRNA and protein expression in 3T3-L1 adipocytes, accompanied by Kelch-Like ECH-Associated Protein (Keap) 1 degradation and increase in the nuclear level of nuclear factor erythroid 2-related factor 2 (Nrf2). Butein modulation of Keap1 and Nrf2 as well as HO-1 upregulation was reversed by pretreatment with p38 MAPK inhibitor SB203580, indicating the involvement of p38 MAPK in butein activation of Nrf2 in adipocytes. In addition, HO-1 activation by butein led to the inhibitions of reactive oxygen species and adipocyte differentiation, as evidenced by the fact that butein repression of reactive oxygen species and adipogenesis was reversed by pretreatment with HO-1 inhibitor SnPP. Induction of HO-1 expression by butein was also demonstrated in the adipose tissue of C57BL/6 mice fed a high-fat diet administered along with butein for three weeks, and correlated with the inhibitions of adiposity and adipose tissue inflammation, which were reversed by co-administration of SnPP. Altogether, our results demonstrate that butein activates the p38 MAPK/Nrf2/HO-1 pathway to act as a potent inhibitor of adipose hypertrophy and inflammation in a diet-induced obesity model and thus has potential for suppressing obesity-linked metabolic syndrome.

Adipose Tissue-Specialized Immunologic Features Might Be the Potential Therapeutic Target of Prospective Medicines for Obesity

Excessive lipid accumulation in adipose tissue is either the source of obesity or the cause and result of chronic local inflammation, and recent studies indicate that the accumulation may induce many other specialized immunologic features with macrophages and epidemic diseases. We analyze the effective stages of immune cells in adipose tissue, including macrophage recruitment, macrophage polarization, and macrophage-like phenotype preadipocyte possession to find optimal sites as drug targets. Subsequently, some main signaling pathways are summarized in this review, including the AMP-activated protein kinase (AMPK) pathway, the JNK signaling pathway, and a novel one, the Notch signaling pathway. We illustrate all these points in order to determine the general pathogenesis of chronic low-grade local inflammation in adipose tissue and the related signaling pathways. In addition, signal-associated prospective compounds, such as berberine, are summarized and discussed with potential targets in pathogenesis. This might provide some possible thoughts and novel therapies for studying chronic inflammatory diseases, such as insulin resistance and type 2 diabetes mellitus.

Interferon Tau Affects Mouse Intestinal Microbiota and Expression of IL-17

This study was conducted to explore the effects of interferon tau (IFNT) on the intestinal microbiota and expression of interleukin 17 (IL-17) in the intestine of mice. IFNT supplementation increased microbial diversity in the jejunum and ileum but decreased microbial diversity in the feces. IFNT supplementation influenced the composition of the intestinal microbiota as follows: (1) decreasing the percentage of Firmicutes and increasing Bacteroidetes in the jejunum and ileum; (2) enhancing the percentage of Firmicutes but decreasing Bacteroidetes in the colon and feces; (3) decreasing Lactobacillus in the jejunum and ileum; (4) increasing the percentage of Blautia, Bacteroides, Alloprevotella, and Lactobacillus in the colon; and (5) increasing the percentage of Lactobacillus, Bacteroides, and Allobaculum, while decreasing Blautia in the feces. Also, IFNT supplementation decreased the expression of IL-17 in the intestines of normal mice and of an intestinal pathogen infected mice. In conclusion, IFNT supplementation modulates the intestinal microbiota and intestinal IL-17 expression, indicating the applicability of IFNT to treat the intestinal diseases involving IL-17 expression and microbiota.

Interferon-alpha inhibits adipogenesis via regulation of JAK/STAT1 signaling

BACKGROUND INFORMATION

Adipose tissue regulates energy metabolism by means of adipocyte hypertrophy and/or the differentiation of pre-existing adipocytes. Excessive production of some cytokines in adipose tissue is known to be a negative regulator of adipocyte differentiation, and the resulting impaired adipogenesis contributes to disorders like insulin resistance. IFN-α is a key immunoregulatory cytokine in the development of type 1 diabetes, lipid disorders and insulin resistance; however, its effect on adipogenesis remains unknown.

METHOD

We examined the effect of IFN-α on adipocyte differentiation and its mechanisms. The effect of IFN-α on adipogenesis was evaluated by Western blotting, qRT-PCR, flow cytometric analysis and Oil Red O staining. We also investigated the role of STAT1 in adipogenesis using gene silencing analysis.

RESULTS

IFN-α inhibited the accumulation of lipid droplets and the expression of adipogenesis related genes. The inhibition of adipocyte differentiation by IFN-α occurred in the early stages of differentiation. IFN-α arrested the cell cycle at the G0/G1 phase and regulated the expression of CDK2 and p21. These results were confirmed in MEF cells. Treatment with IFN-α increased STAT1 phosphorylation, and STAT1 siRNA or inhibitor prevented IFN-α from inhibiting the expression of PPARγ and C/EBPα as well as cell cycle progression in 3T3-L1 cells.

CONCLUSION

We suggest that IFN-α inhibits adipocyte differentiation during the early stage of adipogenesis by regulating the expression of PPARγ and C/EBPα as well as the cell cycle through JAK/STAT1 signaling pathways.

GENERAL SIGNIFICANCE

Our study provides new insights into possible mechanisms of the anti-adipogenetic effects of IFN-α.

The Anti-Inflammatory Effects of Interferon Tau by Suppressing NF-κB/MMP9 in Macrophages Stimulated with Staphylococcus aureus

Previous studies have reported that interferon tau (IFNT) significantly mitigates tissue inflammation. However, this effect and its regulating pathways have not been reported for Staphylococcus aureus-induced inflammation. In this study, RAW 264.7 cells stimulated with S. aureus were used to identify the anti-inflammatory effects and mechanism of IFNT. First, IFNT was found to be noncytotoxic to macrophages treated with the high dose of 200 ng/mL IFNT. ELISA and qPCR revealed that IFNT decreased the expression of proinflammatory cytokines such as TNF-α, IL-1β, and IL-6. TLR2, which is involved in the immune response during S. aureus infection, directly affected NF-κB pathway activation and was also downregulated by IFNT. Subsequent Western blotting showed that the phosphorylation of IκBα and NF-κB p65 was inhibited by IFNT. Therefore, although the MMP9 levels were significantly downregulated in a dose-dependent manner by IFNT, little change in MMP2 was observed in S. aureus-stimulated RAW 264.7 cells. Furthermore, PDTC, an inhibitor of NF-κB, also significantly decreased MMP9 levels by inhibiting NF-κB p65 activation. All of these findings strongly suggested that IFNT suppresses the NF-κB/MMP9 signal transduction pathway and subsequently exerts its anti-inflammatory effects in S. aureus-stimulated RAW 264.7 cells.

Administration of Lactobacillus gasseri SBT2055 suppresses macrophage infiltration into adipose tissue in diet-induced obese mice

Administration of Lactobacillus gasseri SBT2055 (LG2055) has been shown to prevent body weight gain and it also down-regulates the expression of the Ccl2 gene in adipose tissue in diet-induced obese mice. The CC chemokine ligand 2 has a crucial role in macrophage infiltration into adipose tissue, which is known to exacerbate inflammation. However, it is not yet known how LG2055 affects the invasion of macrophages into adipose tissue. C57BL/6J male mice were fed a normal-fat diet (10 % energy fat), high-fat diet (HFD; 45 % energy fat), or HFD containing LG2055 for 12 weeks. After the feeding period, gene expression and macrophage population in adipose tissue were analysed by real-time PCR and flow cytometry, respectively. Body weight and abdominal fat weight were not altered by feeding LG2055. Flow cytometry analysis revealed that the population of macrophages in adipose tissue was significantly reduced by feeding LG2055 compared with HFD only. Furthermore, the ratio of classically activated inflammatory macrophages (M1 macrophages) to total macrophages was significantly decreased in the LG2055-fed group. The expressions of Ccl2, Ccr2 and Lep were down-regulated and that of Il6, Tnf and Nos2 tended to be down-regulated in adipose tissue by feeding LG2055. In addition, fasting glucose levels were significantly decreased in the LG2055-fed group. These data suggest that administration of LG2055 might attenuate inflammation, which is caused by the intake of an HFD, through the inhibition of macrophage invasion into adipose tissue.

Effects of autologous adipose-derived stem cell infusion on type 2 diabetic rats

The effects and possible mechanisms of adipose-derived stem cells (ASC) infusion on type 2 diabetic rats were investigated in this study. Twenty normal male Sprague-Dawley rats were included in normal control group, and 40 male diabetic rats were randomly divided into diabetic control group and ASC group (which received ASC infusion). After therapy, levels of fasting plasma glucose (FPG), HbA1c, serum insulin and C-peptide, recovery of islet cells, inflammatory cytokines, and insulin sensitivity were analyzed. After ASC infusion, compared with diabetic control group, hyperglycemia in ASC group was ameliorated in 2 weeks and maintained for about 6 weeks, and plasma concentrations of insulin and C-peptide were significantly improved (P<0.01). Number of islet β cells and concentration of vWF in islets in ASC group increased, while activity of caspase-3 in islets was reduced. Moreover, concentrations of TNF-α, IL-6 and IL-1β in ASC group obviously decreased (P<0.05). The expression of GLUT4, INSR, and phosphorylation of insulin signaling molecules in insulin target tissues were effectively improved. ASC infusion could aid in T2DM through recovery of islet β cells and improvement of insulin sensitivity. Autologous ASC infusion might be an effective method for T2DM.