Effects of L-Leucine Supplementation and Resistance Training on Adipokine Markers in Untrained Perimenopausal and Postmenopausal Women.

ABSTRACT: Chapman-Lopez, TJ, Funderburk, LK, Heileson, JL, Wilburn, DT, Koutakis, P, Gallucci, AR, and Forsse, JS. Effects of L-leucine supplementation and resistance training on adipokine markers in untrained perimenopausal and postmenopausal women. J Strength Cond Res 38(3): 526-532, 2024-This study examined the effects of supplementing 5 g of leucine compared with a placebo during a 10-week resistance training program on body composition parameters and adipokine concentrations in untrained, perimenopausal and postmenopausal women. Thirty-five women were randomly assigned to 2 groups-leucine (LEU, n = 17) and placebo (PLC, n = 18)-in a double-blind, placebo-controlled trial. Each group consumed the supplement or placebo every day and completed a resistance training program for 10 weeks. Using 3-day food records, a diet was assessed before the intervention and after its cessation. Body composition was assessed preintervention and postintervention using dual-energy x-ray absorptiometry. Moreover, the concentrations of adipokines, such as adiponectin, visfatin, leptin, and monocyte chemoattractant protein-1 (MCP-1), were assessed preintervention and postintervention. Both groups showed an increase in visceral adipose tissue (VAT) area ( p = 0.030) and fat-free mass (FFM; p = 0.023). There were significant group differences in concentrations of visfatin ( p = 0.020) and leptin ( p = 0.038) between the PLC and LEU groups. Visfatin displayed higher concentrations in the PLC group and leptin displayed higher concentrations in the LEU group. In addition, there were significant decreases in adiponectin concentrations for both groups (LEU: 652 ± 513 to 292 ± 447 pg·ml -1 ; PLC: 584 ± 572 to 245 ± 356 pg·ml -1 , p = 0.002) and MCP-1 only decreased in the PLC group (253 ± 119 to 206 ± 106 pg·ml -1 , p = 0.004). There were significant decreases in adiponectin concentrations in both groups and a decrease in MCP-1 concentrations in the PLC group. These decreases may be due to both adipokines possible relationship with VAT area. However, it is not known whether leucine has underlying properties that hinder changes in MCP-1 concentrations.

Morin mitigates cadmium-induced testicular impairment by stimulating testosterone secretion and germ cell proliferation in mice.

Cadmium (Cd) is one of the heavy metal pollutants present in the environment due to human intervention. It is well known that Cd causes toxicological effects on various organs, including the testes. Morin hydrate is a plant-derived bioflavonoid with antioxidant, anti-inflammatory, and anti-stress properties. Thus, the question can be raised as to whether Morin has an effect on Cd-intoxication-induced testicular impairment. Therefore, the aim of this study was to investigate the role of Morin on Cd-mediated disruption of testicular activity. Mice were divided into three groups: group 1 served as the control group, group 2 was given Cd (10 mg/kg) orally for 35 days, and group 3 was given Cd and Morin hydrate (100 mg/kg) for 35 days. To validate the in vivo findings, an in vitro study on testicular explants was also performed. The results of the in vivo study showed that Cd-intoxicated mice had testicular disorganization, reduced circulating testosterone levels, decreased sperm density, and elevated oxidative stress and sperm abnormality. The expression of the germ cell proliferation marker, germ cell nuclear acidic protein (GCNA), and adipocytokine visfatin were also downregulated. It was observed that Morin hydrate upregulated testicular visfatin and GCNA expression in Cd-intoxicated mice, along with improvement in circulating testosterone, testicular histology, and sperm parameters. Furthermore, the in vitro study showed that Cd-mediated downregulation of testicular visfatin and GCNA expression, along with the suppressed secretion of testosterone from testicular explants, was normalized by Morin treatment, whereas visfatin expression was not. Overall, these data indicate that environmental cadmium exposure impairs testicular activity through downregulation of visfatin and GCNA expression, and Morin might play a protective role against Cd-induced testicular toxicity.

Expression and regulation of visfatin/NAMPT in the porcine corpus luteum during the estrous cycle and early pregnancy.

Visfatin/NAMPT creates a hormonal link between energy metabolism and female reproduction. A recent study documented visfatin expression in the ovary and its action on follicular cells; however, the expression of visfatin in luteal cells is still unknown. The aim of this study, therefore, was to investigate the transcript and protein expression of visfatin as well as its immunolocalization in the corpus luteum (CL) and to examine the involvement of extracellular signal-regulated kinases (ERK1/2) in the regulation of visfatin level in response to LH, insulin, progesterone (P4), prostaglandin E2 (PGE2) and F2α (PGF2α). Corpora lutea were harvested from gilts on days 2-3, 10-12 and 14-16 of the estrous cycle and on days 10-11, 12-13, 15-16 and 27-28 of pregnancy. The current study demonstrated that visfatin expression depends on hormonal status related to the phase of the estrous cycle or early pregnancy. Visfatin was immunolocalized to the cytoplasm of small and large luteal cells. Moreover, visfatin protein abundance was increased by P4, and decreased by both prostaglandins, while LH and insulin have modulatory effects, depending on the phase of the cycle. Interestingly, LH, P4 and PGE2 effects were abolished in response to the inhibition of ERK1/2 kinase. Thus, this study demonstrated that expression of visfatin in the porcine CL is determined by the endocrine status related to the estrous cycle and early pregnancy and by the action of LH, insulin, P4 and prostaglandins via activation of the ERK1/2 pathway.

Visfatin increases the invasive potential of ovarian granulosa tumor spheroids by reprogramming glucose metabolism.

In brief: The role of visfatin in ovarian granulosa cell tumor (GCT) invasion and glucose metabolism reprogramming is largely unexplored. These studies imply that visfatin or its inhibitor is involved in regulating ovarian granuloma invasion by reprogramming glucose metabolism and may be a potential candidate for the diagnosis and treatment of ovarian GCT. Abstract: Visfatin is an adipokine with nicotinamide phosphoribosyltransferase (NAMPT) activity, the concentration of which is higher in ascitic fluid than in serum, and is associated with ovarian cancer peritoneal dissemination. Potentially important effects of visfatin on glucose metabolism have been previously reported. However, the mechanism underlying the effects of visfatin on ovarian cancer cell invasion, and whether this involves altered glucose metabolism, has not been elucidated. Here, we tested the hypothesis that visfatin, which can reprogram cancer metabolism, promotes invasion by ovarian cancer spheroids. Visfatin increased glucose transporter (GLUT)1 expression and glucose uptake in adult granulosa cell tumor-derived spheroid cells (KGN) and also increased the activities of hexokinase 2 and lactate dehydrogenase. We showed a visfatin-induced increase in glycolysis in KGN cells. Moreover, visfatin increased the potential invasiveness of KGN spheroid cells by upregulating MMP2 (matrix metalloproteinase 2) and downregulating CLDN3 and CLDN4 (claudin 3 and 4) gene expression. Interestingly, an inhibitor of GLUT1 and lactate dehydrogenase (LDHA) abolished the stimulatory effect of visfatin on the potential invasiveness of KGN cells. More importantly, silencing expression of the NAMPT gene in KGN cells demonstrated its important effect on glycolysis and invasiveness in adult granulosa cell tumor cells (AGCTs). In summary, visfatin appears to increase AGCT invasiveness through effects on glucose metabolism and to be an important regulator of glucose metabolism in these cells.

Affinity-based protein profiling-driven discovery of myricanol as a Nampt activator.

Herein, we synthesized an affinity-based probe of myricanol (pMY) with a photo-affinity cross-linker to initiate a bioconjugation reaction, which was applied for target identification in live C2C12 myotubes. Pull-down of biotinylated pMY coupled with mass spectroscopy and Western blotting revealed that pMY can bind with nicotinamide phosphoribosyltransferase (Nampt), a rate-limiting enzyme in the nicotinamide adenine dinucleotide salvage pathway. Cellular thermal shift assay, drug affinity responsive target stability assay and recombinant protein labeling further validated the direct interaction between myricanol and Nampt. Myricanol did not affect the protein expression of Nampt, but enhanced its activity. Knock-down of Nampt totally abolished the promoting effect of myricanol on insulin-stimulated glucose uptake in C2C12 myotubes. Taken together, myricanol sensitizes insulin action in myotubes through binding with and activating Nampt.

Astrocyte-derived exosomal nicotinamide phosphoribosyltransferase (Nampt) ameliorates ischemic stroke injury by targeting AMPK/mTOR signaling to induce autophagy.

Acute ischemic stroke (AIS) is a global cerebrovascular disease with high disability and mortality, which has no effective therapy. Studies have demonstrated that astrocyte-derived exosomes (ADEXs) provided neuroprotection in experimental stroke models. Nevertheless, the role of exosomes derived from oxygen-glucose-deprivation/reoxygenation-stimulated astrocytes (OGD/R-stimulated astrocytes; OGD/R-ADEXs) in AIS remains largely unknown. Here, we found that OGD/R-ADEXs significantly reduced OGD/R-induced neuronal death and promoted neuronal autophagy. These effects were reversed when astrocytes were pretreated with GW4869, an exosome secretion inhibitor, or when hepatocyte growth factor-regulated tyrosine kinase substrate (Hrs) was knocked down. Neuroprotection was also observed during treatment with OGD/R-ADEXs in vivo. Further studies showed that Nampt, played a vital effect in the regulation of autophagy, was significantly increased in OGD/R-ADEXs. Knockdown of Nampt in astrocytes abolished the above-mentioned effects of OGD/R-ADEXs. Mechanistically, Nampt increased autophagy and decreased cell death by modulating AMPK/mTOR signaling, which recognized as a key signaling pathway of autophagy after AIS. Collectively, these results showed that Nampt released by OGD/R-ADEXs ameliorated acute ischemic stroke during neuronal injury by targeting AMPK/mTOR signaling to induce autophagy. Our study revealed a new key factor in the secretion of exosomes by OGD/R astrocytes, which regulated autophagy and induced neuroprotection in a mouse stroke model.

[Role of nicotinamide phosphoribosyltransferase in delaying smooth muscle cell senescence and protecting abdominal aortic aneurysm].

OBJECTIVE: To investigate the protective effect of nicotinamide phosphoribosyltransferase (NAMPT) on abdominal aortic aneurysm by delaying the senescence of aortic vascular smooth muscle cells (VSMC). METHODS: The primary VSMC cells from normal and patients with abdominal aortic aneurysm were cultured by tissue adherence method. Cells were divided into normal human-derived VSMC group (Ctrl-VSMC group), abdominal aortic aneurysm patient-derived VSMC group (AAA-VSMC group), and angiotensin II (Ang II) in vitro abdominal aortic aneurysm model group (Ang II-VSMC group, 100 nmol/L Ang II treated normal human-derived VSMC for 48 hours), Ang II + P7C3 group and AAA + P7C3 group after NAMPT agonist P7C3 intervention (adding 5 µmol/L P7C3 on the basis of Ang II-VSMC group and AAA-VSMC group, respectively). Immunofluorescence staining was used to identify VSMC; cell proliferation-associated antigen Ki67 staining was used to detect cell proliferation; senescence associated ß-galactosidase (SA-ß-gal) staining was used to detect cell senescence in each group; Western blotting was used to detect the protein expression levels of senescence-related proteins p21, p16 and NAMPT in each group. RESULTS: Compared with the Ctrl-VSMC group, the positive rate of SA-ß-gal staining and the expression levels of senescence-related proteins p21 and p16 in the AAA-VSMC group and Ang II-VSMC group were significantly increased [SA-ß-gal staining positive rate: (74.1±4.4)%, (68.6±5.5)% vs. (36.8±10.3)%, p21/GAPDH: 0.61±0.07, 0.51±0.03 vs. 0.31±0.03, p16/GAPDH: 0.77±0.03, 0.72±0.06 vs. 0.33±0.26, all P < 0.01]. However, the expression of NAMPT was significantly decreased (NAMPT/GAPDH: 0.88±0.07, 0.79±0.14 vs. 1.29±0.02, both P < 0.01). Compared with the Ang II-VSMC group, the positive rate of SA-ß-gal staining and the expressions levels of senescence-related proteins p21 and p16 in the Ang II + P7C3 group were significantly lower [SA-ß-gal staining positive rate: (49.1±3.2)% vs. (68.6±5.5)%, p21/GAPDH: 0.35±0.06 vs. 0.51±0.03, p16/GAPDH: 0.47±0.08 vs. 0.72±0.06, all P < 0.05], while the expression of NAMPT was significantly increased (NAMPT/GAPDH: 1.15±0.06 vs. 0.79±0.14, P < 0.01). Compared with the AAA-VSMC group, the positive rate of SA-ß-gal staining and the expression levels of senescence-related proteins p21 and p16 in the AAA+P7C3 group were significantly lower [SA-ß-gal staining positive rate: (54.1±6.0)% vs. (74.1±4.4)%, p21/GAPDH: 0.38±0.02 vs. 0.61±0.07, p16/GAPDH: 0.50±0.13 vs. 0.77±0.03, all P < 0.05], but the expression of NAMPT was significantly increased (NAMPT/GAPDH: 1.25±0.28 vs. 0.88±0.07, P < 0.01). CONCLUSIONS: NAMPT agonist P7C3 can delay the senescence of VSMC and play a protective role in abdominal aortic aneurysm.

The Functional Effects of Visfatin on Human Left Internal Mammary Artery.

ABSTRACT: Visfatin may play a role in vascular dysfunction in metabolic disorders. Apart from its insulin-mimetic actions, it has divergent actions in the cardiovascular system with discordant results in the literature. Thus, we aimed to study the effects of visfatin on vascular responses of the human left internal mammary artery. Sections of redundant human left internal mammary artery were cut into 3-mm wide rings and hung in 20-mL organ baths containing physiologic salt solution and attached to an isometric force transducer connected to a computer-based data acquisition system. Removing endothelium caused an increase in pD2 values for visfatin-induced relaxation responses (10 -12 -10 -7 M) (9.06 ± 0.21 and 11.08 ± 0.92, respectively). Nicotinamide phosphoribosyltransferase inhibitor FK866 (10 µM) reversed the visfatin-induced relaxations (10 -12 -10 -7 M) ( P = 0.024). Incubations with nitric oxide synthase inhibitor nitro- l -arginine methylester and guanylate cyclase inhibitor 1H-[1,2,4] oxadiazolo [4,3-a] quinoxalin-1-one (ODQ) caused significant reductions in relaxation responses of visfatin ( P = 0.011 and 0.008, respectively). Visfatin incubations decreased relaxation responses to acetylcholine but not to sodium nitroprusside. Incubations with visfatin did not change contractile responses to angiotensin II, endothelin-1, noradrenalin, and phenylephrine. In this study, visfatin caused endothelium-dependent relaxations mediated by nitric oxide-cyclic guanosine monophosphate pathway and nicotinamide phosphoribosyltransferase activity. Furthermore, visfatin-induced decreases in relaxation responses were also related to endothelium-derived nitric oxide.

Crocin ameliorates depressive-like behaviors induced by chronic restraint stress via the NAMPT-NAD+-SIRT1 pathway in mice.

AIM: To investigate the effects of crocin on depression induced by chronic restraint stress (CRS) in mice. METHODS: Depression model was established induced by CRS. All mice were divided into 4 groups randomly: normal group, model group, sertraline group and crocin group. From the 28th day after treatment, serials behaviors were conducted to evaluate the effects of crocin, including sucrose preference test (SPT), tail suspension test (TST), forced swimming test (FST), open field test (OFT), novel objective recognition test (NORT), social interaction test (SIT), and dominance tube test (DTT). Contents of Nicotinamide phosphoribosyltransferase (NAMPT), BDNF, CREB, pCREB and SIRT1 in prefrontal cortex (PFC) were detected by WB. The levels of CORT, DA, 5-HT, NE and NAD+ in PFC were also detected by ELISA. RESULTS: The results showed that crocin ameliorated the depressive-like behaviors, which manifested by increased sucrose consumption ratio and decreased immobility time in FST and TST. Crocin also increased the exploration time and exploration number in T2 phase in NORT, social preference index and social novelty index in SIT, reduced the defensive behavior in DTT. The results of WB showed crocin reversed the decreased contents of NAMPT, SIRT1, BDNF and pCREB/CREB in PFC induced by CRS. Additionally, crocin decreased the expression of cortisol (CORT) and increased the contents of DA, 5-HT, NAD+, but had no effects on NE between groups in PFC. CONCLUSION: In view of the findings, crocin ameliorates depression in mice, which may be associated with regulating NAMPT-NAD+-SIRT1 pathway.

Visfatin inhibits colon cancer cell apoptosis and decreases chemosensitivity to 5­FU by promoting the SDF­1/CXCR4/Akt axis.

5­Fluorouracil (5­FU) is the preferred chemotherapeutic drug used in the treatment of colon cancer; however, drug resistance affects its clinical efficacy. Visfatin, an adipokine that promotes tumour development, has the potential to increase resistance to chemotherapy. The present study aimed to verify the effects of visfatin on the sensitivity of colon cancer cells to 5­FU and to elucidate the potential mechanisms involved. Tissue microarrays (TMAs) were used to analyse visfatin differential expression in normal colon and colon cancer tissues, and the data were further validated in vitro. Cell Counting Kit­8, clone formation, caspase­3/7 activity assays, as well as other analyses were used to verify the effects of visfatin on sensitivity to 5­FU. TMA and correlation analyses were used to predict and verify the correlation between visfatin and stromal cell­derived factor­1 (SDF­1). Rescue experiments and PI3K/Akt inhibitors were used to verify the role of the visfatin/SDF­1/Akt axis in the sensitivity of colon cancer cells to 5­FU. Visfatin was found to be highly expressed in colon cancer tissues and cell lines. Moreover, visfatin knockdown increased apoptosis, reduced cell proliferation and enhanced the chemosensitivity of DLD­1 and SW48 cells to 5­FU. A positive correlation between visfatin and SDF­1 was observed, with the knockdown of visfatin enhancing cell sensitivity to 5­FU chemotherapy by targeting the SDF­1/C­X­C chemokine receptor type 4 (CXCR4) axis. Furthermore, the Akt signalling pathway downstream of SDF­1/CXCR4 proved to be critical in the decreased sensitisation of colon cancer cells to 5­FU induced by visfatin. On the whole, the present study demonstrates that visatin can potentially decrease colon cancer cell apoptosis, promote proliferation and decrease colon cancer cell sensitivity to 5­FU via the visfatin/SDF­1/Akt axis.

Circular RNA triple functional domain promotes osteoarthritis' development by modulating the microRNA-136-5p/Nicotinamide phosphoribosyltransferase axis.

Numerous studies have affirmed the participation of circular RNA (circRNA) in osteoarthritis (OA)' development. Previous studies have exposed the elevation of the circRNA triple functional domain (TRIO) in OA, while the molecular mechanism of its effect on OA remains ambiguous. During the study, it was discovered the up-regulation of circTRIO in OA rats and interleukin-1ß-treated chondrocytes. Knockdown circTRIO facilitates chondrocyte viability, but suppresses the inflammation, the apoptosis, and matrix metalloproteinases (MMP)-3 and MMP-13 expression, whereas up-regulation aggravates OA. The effect of up-regulation or under-expression of circTRIO on chondrocytes was reversed via the knockdown of Nicotinamide phosphoribosyltransferase (NAMPT) or microRNA (miR)-136-5p separately. Mechanically speaking, circTRIO competitively adsorbing miR-136-5p to target NAMPT influences OA. Briefly, the results of this study inform that the circTRIO/miR-136-5p/NAMPT axis is momentous in OA progression and is supposed to be a promising therapeutic target for some time.

Palmitate-mediated induction of neuropeptide Y expression occurs through intracellular metabolites and not direct exposure to proinflammatory cytokines.

A contributing factor to the development of obesity is the consumption of a diet high in saturated fatty acids, such as palmitate. These fats induce hypothalamic neuroinflammation, which dysregulates neuronal function and induces orexigenic neuropeptide Y (Npy) to promote food intake. An inflammatory cytokine array identified multiple candidates that could mediate palmitate-induced up-regulation of Npy mRNA levels. Of these, visfatin or nicotinamide phosphoribosyltransferase (NAMPT), macrophage migratory inhibitory factor (MIF), and IL-17F were chosen for further study. Direct treatment of the neuropeptide Y/agouti-related peptide (NPY/AgRP)-expressing mHypoE-46 neuronal cell line with the aforementioned cytokines demonstrated that visfatin could directly induce Npy mRNA expression. Preventing the intracellular metabolism of palmitate through long-chain acyl-CoA synthetase (ACSL) inhibition was sufficient to block the palmitate-mediated increase in Npy gene expression. Furthermore, thin-layer chromatography revealed that in neurons, palmitate is readily incorporated into ceramides and defined species of phospholipids. Exogenous C16 ceramide, dipalmitoyl-phosphatidylcholine, and dipalmitoyl-phosphatidylethanolamine were sufficient to significantly induce Npy expression. This study suggests that the intracellular metabolism of palmitate and elevation of metabolites, including ceramide and phospholipids, are responsible for the palmitate-mediated induction of the potent orexigen Npy. Furthermore, this suggests that the regulation of Npy expression is less reliant on inflammatory cytokines per se than palmitate metabolites in a model of NPY/AgRP neurons. These lipid species likely induce detrimental downstream cellular signaling events ultimately causing an increase in feeding, resulting in an overweight phenotype and/or obesity.

Small Extracellular Vesicles Derived from Adipocytes Attenuate Intervertebral Disc Degeneration in Rats by Rejuvenating Senescent Nucleus Pulposus Cells and Endplate Cells by Delivering Exogenous NAMPT.

Cellular senescence is a key factor in the development of intervertebral disc degeneration (IVDD). Age-associated decreases in NAD+ levels play a critical role in regulating cellular senescence. Previous studies have found that small extracellular vesicles (sEVs) secreted by adipocytes (Adipo-sEVs) or adipose tissue are abundant in nicotinamide phosphoribosyltransferase (NAMPT), which is the key NAD+ biosynthetic enzyme in mammals. Systemic injection of these sEVs significantly improves physical activity and extends the lifespan of aged mice by increasing NAD+ levels. However, to date, the therapeutic potential of Adipo-sEVs in other age-associated disease models, such as IVDD, has not been explored. In this study, we investigated the therapeutic effects of Adipo-sEVs on senescence of nucleus pulposus cells (NPCs) and cartilaginous endplate cells (EPCs). In vitro, Adipo-sEVs could rejuvenate the senescence of NPCs and EPCs. Age-related dysfunctions were also ameliorated by Adipo-sEVs by delivering NAMPT and activating NAD+ biosynthesis and the Sirt1 pathway. Further in vivo experiments revealed that Adipo-sEV-mediated delivery of NAMPT attenuated IVDD in rats by rejuvenating senescent NPCs and EPCs. Collectively, the results indicate a new cell-free tool and provide a promising sEV-mediated delivery method of NAMPT as a therapeutic approach for IVDD clinically.

Exploring the Crosstalk between Hydrostatic Pressure and Adipokines: An In Vitro Study on Human Osteoarthritic Chondrocytes.

Obesity is a risk factor for osteoarthritis (OA) development and progression due to an altered biomechanical stress on cartilage and an increased release of inflammatory adipokines from adipose tissue. Evidence suggests an interplay between loading and adipokines in chondrocytes metabolism modulation. We investigated the role of loading, as hydrostatic pressure (HP), in regulating visfatin-induced effects in human OA chondrocytes. Chondrocytes were stimulated with visfatin (24 h) and exposed to high continuous HP (24 MPa, 3 h) in the presence of visfatin inhibitor (FK866, 4 h pre-incubation). Apoptosis and oxidative stress were detected by cytometry, B-cell lymphoma (BCL)2, metalloproteinases (MMPs), type II collagen (Col2a1), antioxidant enzymes, miRNA, cyclin D1 expressions by real-time PCR, and ß-catenin protein by western blot. HP exposure or visfatin stimulus significantly induced apoptosis, superoxide anion production, and MMP-3, -13, antioxidant enzymes, and miRNA gene expression, while reducing Col2a1 and BCL2 mRNA. Both stimuli significantly reduced ß-catenin protein and increased cyclin D1 gene expression. HP exposure exacerbated visfatin-induced effects, which were counteracted by FK866 pre-treatment. Our data underline the complex interplay between loading and visfatin in controlling chondrocytes' metabolism, contributing to explaining the role of obesity in OA etiopathogenesis, and confirming the importance of controlling body weight for disease treatment.

Visfatin Regulates Inflammatory Mediators in Mouse Intestinal Mucosa Through Toll-Like Receptors Signaling Under Lipopolysaccharide Stress.

Visfatin is a multifunctional protein involved in inflammatory immune stress. The aim of current study was to explore the role of visfatin in lipopolysaccharide (LPS)-induced intestinal mucosal inflammation and to confirm its cellular effect in inflammatory immune response through silencing of Toll-like receptors (TLRs). We divided Kunming mice into three groups: Saline group, LPS group, and LPS + visfatin group and performed hematoxylin and eosin staining, immunohistochemistry, quantitative polymerase chain reaction, Western blot, enzyme linked immunosorbent assay and RNA-seq analysis. Pretreatment of visfatin improves LPS-stimulated reduction of tight junction protein 1 (ZO-1) and secretory immunoglobulin A, inhibits overexpression of Claudin-1 and vascular endothelial growth factor, and reduces intestinal mucosal damage and inflammation. RNA-seq analysis of cellular transcriptomes indicated that visfatin is involved in down-regulation of mRNA level of TLR4 as well as attenuation of protein levels of TLR8 and nucleotide-binding oligomerization domain-containing protein 2, revealing that visfatin could reduce intestinal mucosal inflammation through TLR signaling pathway in mice ileum. In RAW264.7 cells, the genes silencing of Toll/IL-1R family, such as TLR4, TLR2, and IL-1R1, was accompanied by decreased expressions of inflammatory factors (TNF-α, IL-1ß, IL-6 and MCP-1) along with lower cellular visfatin levels. Hence, visfatin maintains the intestinal mucosal barrier structure and attenuates the intestinal mucosal inflammation through the TLR signaling pathway. Likewise, the Toll/IL-1R family regulates the release of visfatin, which can participate in the inflammatory reaction through the regulation of inflammatory factors.

Visfatin relieves myocardial ischemia-reperfusion injury through activation of PI3K/Akt/HSP70 signaling axis.

OBJECTIVE: Myocardial ischemia-reperfusion injury (MIRI) is the most common complication of ischemic cardiomyopathy, which severely affects the prognosis of patients. The purpose of this study was to investigate the protective effects of visfatin on the myocardium after ischemia-reperfusion (I/R) and its mechanism. MATERIALS AND METHODS: Sprague Dawley rats were used to construct the MIRI model and visfatin was administrated intraperitoneally in rats to determine the protective effect of visfatin on myocardium after I/R. In addition, visfatin was used to treat rat myocardial cell line H9c2 cells and detect its effect on H9c2 cells. The effect of visfatin on the PI3K/Akt/HSP70 signaling axis in H9c2 cells was also detected to determine the mechanism of the myocardial protection of visfatin. RESULTS: The damage of cardiomyocytes in MIRI rats pretreated with visfatin was significantly improved compared with untreated MIRI rats. Visfatin also reduced the level of inflammation and apoptosis of cardiomyocytes in MIRI rats, reduced myocardial injury markers, and improved cardiac function. In vitro, visfatin also reduced inflammatory and apoptotic factors in H9c2 cells. In addition, visfatin also promoted the activity of the PI3K/Akt signaling pathway and increased HSP70 expression in H9c2 cells. The inhibition of the PI3K/Akt signaling pathway was found to attenuate the promotion of HSP70 by visfatin. SiRNA-HSP70 also attenuated the protective effect of visfatin on H9c2 cells. CONCLUSIONS: Visfatin reduces the inflammation and apoptosis levels of myocardial cells through the PI3K/Akt/HSP70 signaling axis, thereby reducing I/R-induced myocardial injury.

CCL20 induced by visfatin in macrophages via the NF-κB and MKK3/6-p38 signaling pathways contributes to hepatic stellate cell activation.

Chemokines interact with hepatic resident cells during inflammation and fibrosis. CC chemokine ligand (CCL) 20 has been reported to be important in inflammation and fibrosis in the liver. We hypothesized that visfatin, an adipocytokine, could play a role in hepatic fibrosis via CCL20. We investigated the effect of visfatin on CCL20 in THP-1 human promonocytic cells and examined the molecular mechanisms involved. Following treatment of THP-1 cells with visfatin, CCL20 expression and secretion were assessed. We assessed the intracellular signaling molecules IKK/NF-κB, JAK2/STAT3, MAPKs, and MKK3/6 by western blotting. We treated THP-1 cells with visfatin and signaling inhibitors, and examined CCL20 mRNA and protein levels. To investigate the effect of visfatin-induced CCL20 expression in hepatic stellate cells (HSCs), LX-2 cells were co-cultured with the culture supernatant of THP-1 cells with or without anti-CCL20 neutralizing antibodies, and fibrosis markers were examined by RT-PCR and immunoblotting. In THP-1 cells, visfatin increased the CCL20 mRNA and protein levels. visfatin increased the activities of the NF-κB, p38, and MLK3/6 signaling pathways but not those of the JAK2/STAT3 and ERK pathways. Visfatin treatment together with an NF-κB, p38, or MLK3 inhibitor reduced the mRNA and protein levels of CCL20. The visfatin-induced CCL20 increased the expression of fibrosis markers and CCR6 in HSCs. Following neutralization of CCL20, the levels of fibrosis markers and CCR6 were decreased. Visfatin increases the expression of CCL20 via the NF-κB and MKK3/6-p38 signaling pathways in macrophages, and visfatin-induced CCL20 expression promotes the fibrosis markers in HSCs.

Visfatin Exerts Immunotherapeutic Effects in Lipopolysaccharide-Induced Acute Lung Injury in Murine Model.

Visfatin acts as a significant regulator of inflammatory cytokines. However, the immunological response and therapeutic effects of visfatin under bacterial stress in murine lung tissue are still not clear. To investigate the role of visfatin on lipopolysaccharide (LPS)-induced acute lung injury (ALI), thirty Kunming mice were divided into Saline, LPS, and LPS + visfatin groups. After routine blood examination, the effects of visfatin on inflammatory cytokines, lung tissue structure, and expression of inflammatory mediators were explored through hematoxylin-eosin (H&E), Masson and immunohistochemical staining, quantitative polymerase chain reaction (Q-PCR), and Western blotting. Compared with the Saline group, neutrophil percentage, peripheral blood neutrophil count, and the ratio of lymphocyte count (NLR) were upregulated in LPS group. Moreover, Masson staining showed alterations in lung tissue structure; the mRNA level of different cytokines (IL-6, IL-1ß, TNF-α, IL-10, TLR4, IFN-γ) was upregulated; and the protein expression of interleukin (IL)-6, myeloperoxidase (MPO), and transforming growth factor-ß1 (TGF-ß) was significantly (p < 0.05) different in LPS group. Compared with LPS group, neutrophil percentage significantly decreased (p < 0.01), the numbers of lymphocytes significantly (p < 0.05) increased, NLR decreased, Masson staining of the lung was extremely different (p < 0.01), the structure of the lung was slightly damaged, and the myeloperoxidase values of lung showed no differences in LPS + visfatin. Hence, visfatin inhibits the lung inflammation induced by ALI. During the ALI, visfatin acts by decreasing NLR, downregulated the expression of MPO, enhanced antioxidant capacity, and regulated the inflammatory factors IL-1ß, IL-6, IL-10, and TNF-α to reduce the lung injury.

Visfatin Induces Inflammation and Insulin Resistance via the NF-κB and STAT3 Signaling Pathways in Hepatocytes.

BACKGROUND: It has been suggested that visfatin, which is an adipocytokine, exhibits proinflammatory properties and is associated with insulin resistance. Insulin resistance and inflammation are the principal pathogeneses of nonalcoholic fatty liver disease (NAFLD), but the relationship, if any, between visfatin and NAFLD remains unclear. Here, we evaluated the effects of visfatin on hepatic inflammation and insulin resistance in HepG2 cells and examined the molecular mechanisms involved. METHODS: After treatment with visfatin, the inflammatory cytokines IL-6, TNF-α, and IL-1ß were assessed by real-time polymerase chain reaction (RT-PCR) and immunocytochemical staining in HepG2 cells. To investigate the effects of visfatin on insulin resistance, we evaluated insulin-signaling pathways, such as IR, IRS-1, GSK, and AKT using immunoblotting. We assessed the intracellular signaling molecules including STAT3, NF-κB, IKK, p38, JNK, and ERK by western blotting. We treated HepG2 cells with both visfatin and either AG490 (a JAK2 inhibitor) or Bay 7082 (an NF-κB inhibitor); we examined proinflammatory cytokine mRNA levels using RT-PCR and insulin signaling using western blotting. RESULTS: In HepG2 cells, visfatin significantly increased the levels of proinflammatory cytokines, reduced the levels of proteins (e.g., phospho-IR, phospho-IRS-1 (Tyr612), phospho-AKT, and phospho-GSK-3α/ß) involved in insulin signaling, and increased IRS-1 S307 phosphorylation compared to controls. Interestingly, visfatin increased the activities of the JAK2/STAT3 and IKK/NF-κB signaling pathways but not those of the JNK, p38, and ERK pathways. Visfatin-induced inflammation and insulin resistance were regulated by JAK2/STAT3 and IKK/NF-κB signaling; together with AG490 or Bay 7082, visfatin significantly reduced mRNA levels of IL-6, TNF-α and IL-1ß and rescued insulin signaling. CONCLUSION: Visfatin induced proinflammatory cytokine production and inhibited insulin signaling via the STAT3 and NF-κB pathways in HepG2 cells.

Visfatin Promotes Monocyte Adhesion by Upregulating ICAM-1 and VCAM-1 Expression in Endothelial Cells via Activation of p38-PI3K-Akt Signaling and Subsequent ROS Production and IKK/NF-κB Activation.

BACKGROUND/AIMS: Visfatin is known to act as a mediator in several metabolic disorders, such as obesity, diabetes, and cardiovascular diseases. This study aimed to investigate the effect of visfatin on the adhesion of THP-1 monocytes to human vascular endothelial cells and the underlying mechanism. METHODS: Monocytes adhesion to endothelial cells was determined by using fluorescence-labeled monocytes. ICAM-1 and VCAM-1 expression in endothelial cells were measured by western blotting. Production of reactive oxygen species (ROS) was measured by using a fluorescent dye. The amounts of nuclear factor-kappa B (NF-κB) and phosphorylation of inhibitory factor of NF-κB (IκB) were determined by using western blot analysis. The translocation of NF-κB from the cytoplasm to the nucleus was determined by using immunofluorescence. RESULTS: Here we showed that visfatin significantly caused the upregulation of intercellular cell adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1) in endothelial cells, as well as enhanced monocyte adhesion to endothelial cells. Moreover, we found that inhibition of PI3K, Akt, and p38 MAPK activation significantly prevented visfatin-enhanced expression of ICAM-1 and VCAM-1 and monocyte adhesion to endothelial cells. Visfatin enhanced ROS production and IKK/NF-кB activation and then led to upregulation of ICAM-1 and VCAM-1 and enhanced monocyte adhesion to endothelial cells. These effects were also p38/PI3K/Akt-dependent. CONCLUSION: These results demonstrated that visfatin promoted monocyte-endothelial cell adhesion by increasing ICAM-1 and VCAM-1 expression via the activation of p38/PI3K/Akt signaling and downstream ROS production and IKK/NF-кB activation.