Adiponectin Knockout Mice Research Articles

Exercise-induced AMPK activation and IL-6 muscle production are disturbed in adiponectin knockout mice

BackgroundAdiponectin exhibits anti-inflammatory actions and is mainly expressed in adipose tissue. However, recent studies have shown that adiponectin can also be secreted by skeletal muscle fibers with autocrine and paracrine effects. ObjectivesTo analyze the role of adiponectin in the metabolic and inflammatory response of skeletal muscle after acute exhaustive aerobic exercise. MethodsC57BL/6 (WT) and adiponectin knockout (AdKO) mice underwent four days of treadmill running adaptation and at the fifth day, they performed an incremental maximum test to determine the maximum speed (Vmax). Acute exercise consisted of one hour at 60% Vmax. Mice were euthanatized 2 and 24 h after acute exercise session. ResultsSerum and gastrocnemius adiponectin increased after 2-hours of acute exercise. NEFA concentrations were lower in non-exercise AdKO, and decreased 2-hours after exercise only in WT. No differences were found in muscle triacylglycerol content; however, glycogen content was higher in AdKO in non-exercise (p-value = 0.005). WT showed an increase in AMP-activated protein kinase (AMPK) phosphorylation 2-hours after exercise and its level went back to normal after 24-hours. Otherwise, exercise was not able to modify AMPK in the same way as in AdKO. WT showed an increase in the phosphorylation of ACC (Ser79) 2-hours after exercise and return to normal after 24-hours of exercise (p-value < 0.05), kinects that was not observed in AdKO mice. IL-10 and IL-6 concentration was completely different among genotypes. In WT, these cytokines were increased at 2 (p-value < 0.01) and 24 h (p-value < 0.001) after exercise when compared with AdKO. NF-κBp65 protein and gene expression were not different between genotypes. ConclusionAdiponectin influences muscle metabolism, mainly by the decrease in exercise-induced AMPK phosphorylation, inflammatory profile and IL-6 in the muscle.

Targeting mTOR and Src restricts hepatocellular carcinoma growth in a novel murine liver cancer model.

Liver cancer is a poor prognosis cancer with limited treatment options. To develop a new therapeutic approach, we derived HCC cells from a known model of murine hepatocellular carcinoma (HCC). We treated adiponectin (APN) knock-out mice with the carcinogen diethylnitrosamine, and the resulting tumors were 7-fold larger than wild-type controls. Tumors were disassociated from both genotypes and their growth characteristics evaluated. A52 cells from APN KO mice had the most robust growth in vitro and in vivo, and presented with pathology similar to the parental tumor. All primary tumors and cell lines exhibited activity of the mammalian target of Rapamycin (mTOR) and Src pathways. Subsequent combinatorial treatment, with the mTOR inhibitor Rapamycin and the Src inhibitor Dasatinib reduced A52 HCC growth 29-fold in vivo. Through protein and histological analyzes we observed activation of these pathways in human HCC, suggesting that targeting both mTOR and Src may be a novel approach for the treatment of HCC.

An adiponectin-S1P axis protects against lipid induced insulin resistance and cardiomyocyte cell death via reduction of oxidative stress

BackgroundAdiponectin exerts several beneficial cardiovascular effects, however their specific molecular mechanisms require additional understanding. This study investigated the mechanisms of adiponectin action in the heart during high fat diet (HFD) feeding or in palmitate (PA) treated H9c2 cardiomyoblasts.Methods6-week-old male adiponectin knock out (Ad-KO) mice were fed chow or 60% HFD for 6 weeks then received saline or recombinant adiponectin (3μg/g body weight) for an additional 2 weeks. After acute insulin stimulation (4 U/kg), tissue and serum samples were collected for analysis. H9c2 cardiomyocytes were treated ±0.1 mM PA, the adiponectin receptor agonist AdipoRon, or the antioxidant MnTBAP then assays to analyze reactive oxygen species (ROS) production and cell death were conducted. To specifically determine the mechanistic role of S1P, gain and loss of function studies were conducted with adding S1P to cells or the inhibitors THI and SKI-II, respectively.ResultsHFD feeding induced cardiac insulin resistance in Ad-KO mice, which was reversed following replenishment of normal circulating adiponectin levels. In addition, myocardial total triglyceride was elevated by HFD and lipidomic analysis showed increased levels of ceramides and sphingosine-1-phosphate (S1P), with only the latter being corrected by adiponectin administration. Similarly, treatment of H9C2 cardiomyoblasts with PA led to a significant increase of intracellular S1P but not in conditioned media whereas AdipoRon significantly increased S1P production and secretion from cells. AdipoRon or the antioxidant MnTBAP significantly reduced PA-induced cell death. Gain and loss of function studies suggested S1P secretion and autocrine receptor activation mediated the effect of AdipoRon to attenuate PA-induced ROS production and cell death.ConclusionOur data establish adiponectin signaling-mediated increase in S1P secretion as a mechanism via which HFD or PA induced cardiomyocyte lipotoxicity, leading to insulin resistance and cell death, is attenuated.

An Adiponectin Receptor Agonist Reduces Type 2 Diabetic Periodontitis

Periodontitis is twice as prevalent in diabetics as in nondiabetics, and type 2 diabetes (T2D)–associated periodontitis is severe in many cases due to the altered and aberrant functions of bone cells in hyperglycemic conditions. Therefore, developing an effective method to halt the disease process, as well as restore and regenerate lost alveolar bone to reserve the natural teeth in diabetics, is critically important. In the current study, we applied a newly discovered adiponectin receptor agonist AdipoRon (APR) in experimental periodontitis in diabetic animal models and demonstrated the underlying molecular mechanisms. We found that when APR systemically quenched the blood sugar level in diet-induced obesity (DIO) diabetic mice, it reduced osteoclast numbers and alveolar bone loss significantly due to APR’s inhibition on osteoclast differentiation shown in our in vitro studies. APR also decreased the production of proinflammatory molecules CC chemokine ligand 2 and interleukin 6 in diseased gingival tissues. On the other hand, APR promoted alveolar bone regeneration through enhancing osteogenic differentiation and decreasing stromal cell–derived factor 1 in the bone marrow that facilitates stem cell migration. Same results were achieved by APR treatment of periodontitis induced in adiponectin (APN) knockout mice, indicating the ability of APR to activate the endogenous APN receptors to exert osteoanabolic effects. In summary, our study supports the notion that APR could be used as an effective multipronged approach to target T2D-associated periodontitis.

Adiponectin Mediates Running-Restored Hippocampal Neurogenesis in Streptozotocin-Induced Type 1 Diabetes in Mice.

Streptozotocin (STZ)-induced diabetes impairs learning and memory performance and reduces adult hippocampal neurogenesis. Physical exercise brings beneficial effects. We have previously shown that adiponectin, an adipocyte-secreted hormone critically involved in the pathology of diabetes, is a key mediator for exercise-enhanced adult hippocampal neurogenesis. Here, we tested whether adiponectin is required for exercise to restore adult hippocampal neurogenesis in an animal model of diabetes. The findings showed that a single injection of 195 mg/kg STZ-induced diabetes significantly increased serum levels of corticosterone and reduced hippocampal adiponectin levels in adult mice. STZ injection also significantly reduced the number of Ki67 and doublecortin (DCX) positive cells and the ratio of co-labeling of DCX and bromodeoxyuridine (BrdU) in the hippocampal dentate region, indicating a decrease in adult hippocampal neurogenesis. Two-week voluntary wheel running significantly restored hippocampal neurogenesis in the diabetic wild-type mice, but not adiponectin knockout mice, indicating that adiponectin is critical for physical exercise to restore hippocampal adult neurogenesis in mice with diabetes. The results suggest that increasing adiponectin levels could be a therapeutic approach to restore hippocampal neurogenesis impairment in individuals with diabetes.

APPL2 Promotes Inflammation in Mouse Liver by Negative Regulation of Adiponectin Signaling

Adiponectin is an insulin sensitizer that exerts antidiabetes and anti-inflammation functions. Adiponectin signaling is negatively regulated by the adaptor protein APPL2 in cells, yet the in vivo roles of APPL2 remains largely unknown. In this study, we show that liver-specific knockout of APPL2 improved insulin sensitivity and enhanced adiponectin signaling in high fat diet (HFD)-fed mice. The liver-specific APPL2 knockout mice (APPL2LKO) had less macrophage infiltration in liver tissues compared with their wild type controls and were resistant to LPS-induced expression of inflammatory genes such as IL-6, IL-1α, MCP-1, and TNF-α. Pretreatment of macrophage Raw264.7 cells with conditioned media from primary hepatocytes of APPL2LKO mice attenuated LPS-stimulated expression of inflammatory genes and the migration of the cells. The anti-inflammatory effect of APPL2 knockout was significantly reduced in adiponectin and liver-specific APPL2 double knockout mice (AdiponectinKO/APPL2LKO). Taken together, our results show that APPL2 promotes inflammation in mouse liver and the protein exerts a pro-inflammatory role by antagonizing adiponectin signaling. Disclosure J. Ryu: None.

BETA3-ADRENOCEPTOR MEDIATED ADIPONECTIN SECRETION IS ESSENTIAL IN MODULATION OF VASCULAR TONE BY PERIVASCULAR ADIPOSE TISSUE

Objective: Healthy perivascular adipose tissue (PVAT) exerts an anti-contractile effect which is vital in regulating blood pressure. Evidence suggests that sympathetic nervous stimulation of PVAT triggers activation of adipocyte beta3-adrenoceptors, and the subsequent release of the vasoactive adipokine adiponectin. In obesity plasma adiponectin is reduced, which may result in a loss of PVAT function and subsequent hypertension. Therefore we examined beta3-adrenoceptor and adiponectin function in the PVAT anti-contractile effect. Design and method: Body weight, blood pressure, and blood glucose were measured in control C57 mice, and adiponectin knockout (Adipo-/-) mice. Following sacrifice, electrical field stimulation (EFS) profiles of isolated C57 and Adipo-/- mesenteric and skeletal muscle resistance arteries (<250 μm, ± PVAT) were characterised using wire myography. Sympathetic denervation of PVAT using 6-hydroxydopamine (6-OHDA) was performed. Beta3-adrenoceptor function was investigated using the agonist CL-316,243 and antagonist SR59203A. The role of the adipokine adiponectin was examined using exogenous adiponectin and a blocking peptide for adiponectin receptor 1 (ABP). The concentration of adiponectin secretion upon EFS was measured using an ELISA kit. Results: Adipo-/- mice exhibit significant elevations in both blood pressure and blood glucose. During EFS of isolated ± PVAT arteries, mesenteric and skeletal muscle PVAT from C57 mice elicited an anti-contractile effect, which was absent in the Adipo-/-. Sympathetic denervation of both mesenteric and skeletal muscle PVAT abolished the anti-contractile effect. Inhibition of beta3-adrenoceptors in C57 mesenteric and skeletal muscle PVAT using SR59230A significantly reduced the anti-contractile effect, however activation of beta3-adrenoceptors in Adipo-/- PVAT using CL-316,243 did not restore function. Application of exogenous adiponectin to C57 mesenteric and skeletal muscle –PVAT arteries caused a significant vasodilation. In ± PVAT arteries, incubation with ABP significantly reduced the anti-contractile effect. Using an ELISA, adiponectin secretion from PVAT upon EFS was significantly reduced when incubated with SR59230A. Conclusions: These results demonstrate that upon sympathetic stimulation, PVAT from two different vascular beds releases adiponectin via activation of beta3-adrenoreceptors, exerting an anti-contractile effect on the blood vessels. In the absence of adiponectin PVAT anti-contractile function is lost, resulting in hypertension and hyperglycaemia, highlighting the importance of adiponectin in vascular function.

The role of adiponectin in exercise training‐induced vascular adaptation

We have previously reported that in old rats, reversal of age‐related vascular dysfunction by exercise training correlates with an increase in circulating adiponectin and its signaling within coronary vascular smooth muscle. In the current study, we investigated the effect of deletion of adiponectin on exercise training‐induced vascular adiponectin. C57BL/6 wild‐type (WT) or homozygous adiponectin knockout (AdipoKO) mice were obtained at 10–12 wks of age and underwent treadmill exercise training (EX) (12 m/min, 5° incline, 1 hr/day, 5 days/wk for 8 wks) or remained sedentary (SED) in cages. Arterioles isolated from cardiac and soleus muscle were assessed for contractile and vasodilatory function, and capillarity of the soleus muscle was evaluated. Exercise training increased flow‐induced dilation significantly in coronary arterioles of WT mice (P&lt;0.01 EX vs. SED), but decreased flow‐induced dilation in coronary arterioles from AdipoKO mice. ACh‐induced dilation was reduced in coronary arterioles from AdipoKO mice as compared to those from WT mice (P&lt;0.05 AdipoKO vs. WT). Exercise training reduced ACh‐induced dilation in arterioles from WT mice, but increased ACh‐induced dilation in arterioles from AdipoKO mice. Baseline capillarity increased in the soleus muscle of AdipoKO mice as compared to WT mice, but an exercise training‐induced increase in capillarity, detected in WT mice, was absent in AdipoKO mice. Contractile responsiveness to phenylephrine was increased in arterioles from the soleus muscle of both WT and AdipoKO mice (P&lt;0.01 EX vs. SED in both WT and AdipoKO). These data indicate that adiponectin is a critical contributor to exercise training‐induced vascular adaptations; however, locally produced adiponectin may be more critical than circulating adiponectin in mediating these adaptations.Support or Funding InformationFlorida State University College of MedicineThis abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Role of Sympathetic Nerves and Adipocyte Catecholamine Uptake in the Vasorelaxant Function of Perivascular Adipose Tissue.

Healthy perivascular adipose tissue (PVAT) exerts an anticontractile effect on resistance arteries which is vital in regulating arterial tone. Activation of β3-adrenoceptors by sympathetic nerve-derived NA (noradrenaline) may be implicated in this effect and may stimulate the release of the vasodilator adiponectin from adipocytes. Understanding the mechanisms responsible is vital for determining how PVAT may modify vascular resistance in vivo. Electrical field stimulation profiles of healthy C57BL/6J mouse mesenteric resistance arteries were characterized using wire myography. During electrical field stimulation, PVAT elicits a reproducible anticontractile effect, which is endothelium independent. To demonstrate the release of an anticontractile factor, the solution surrounding stimulated exogenous PVAT was transferred to a PVAT-denuded vessel. Post-transfer contractility was significantly reduced confirming that stimulated PVAT releases a transferable anticontractile factor. Sympathetic denervation of PVAT using tetrodotoxin or 6-hydroxydopamine completely abolished the anticontractile effect. β3-adrenoceptor antagonist SR59203A reduced the anticontractile effect, although the PVAT remained overall anticontractile. When the antagonist was used in combination with an OCT3 (organic cation transporter 3) inhibitor, corticosterone, the anticontractile effect was completely abolished. Application of an adiponectin receptor-1 blocking peptide significantly reduced the anticontractile effect in +PVAT arteries. When used in combination with the β3-adrenoceptor antagonist, there was no further reduction. In adiponectin knockout mice, the anticontractile effect is absent. The roles of PVAT are 2-fold. First, sympathetic stimulation in PVAT triggers the release of adiponectin via β3-adrenoceptor activation. Second, PVAT acts as a reservoir for NA, preventing it from reaching the vessel and causing contraction.

Adiponectin regulates thermal nociception in a mouse model of neuropathic pain

BackgroundAdiponectin, a cytokine secreted by adipocytes, plays an important role in regulating glucose and lipid metabolism. However, the role of adiponectin in pain conditions is largely unknown. This study aimed to identify the role and mechanism of adiponectin in nociceptive sensitivity under physiological and pathological states utilising adiponectin knockout (KO) mice. MethodsWild type (WT) and adiponectin KO mice were subjected to partial sciatic nerve ligation (pSNL) or sham operation. Pain-like behavioural tests, including thermal allodynia, hyperalgesia, and mechanical allodynia, were performed before and after pSNL from Day 3–21. Dorsal root ganglions (DRGs), lumbar spinal segments at L3-5, and somatosensory cortex were collected for protein measurement via western blotting and immunofluorescence staining. ResultsCompared with WT mice, KO mice had significantly lower (40–50%) paw withdrawal latency to innocuous and noxious stimuli before and after pSNL. In DRG neurones from KO mice, where adiponectin receptor (AdipoR) 2 is located, phosphorylated p38 mitogen-activated protein kinase (p-p38 MAPK) and heat-sensitive transient receptor potential cation channel subfamily V member 1 (TRPV1) were significantly higher (by two- to three-fold) than from WT mice. In spinal microglia and somatosensory cortical neurones, where AdipoR1 is mainly located, p-p38 MAPK and TRPV1 were also higher (by two- to three-fold) in KO compared with WT mice, and altered signalling of these molecules was exacerbated (1.2- to 1.3-fold) by pSNL. ConclusionsOur results show that adiponectin regulates thermal nociceptive sensitivity by inhibiting activation of DRG neurones, spinal microglia, and somatosensory cortical neurones in physiological and neuropathic pain states. This study has relevance for patients with adiponectin disorders, such as obesity and diabetes.

Adiponectin deficiency-induced diabetes increases TNFα and FFA via downregulation of PPARα.

Expression of peroxisome proliferator-activated receptor (PPAR) α was investigated in adiponectin knockout mice to elucidate the relationship between PPARα and adiponectin deficiency-induced diabetes. Adiponectin knockout (Adp−/−) mice were generated by gene targeting. Glucose tolerance test (GTT), insulin tolerance test (ITT), and organ sampling were performed in Adp−/− mice at the age of 10 weeks. PPARα, insulin, triglyceride, free fatty acid (FFA), and tumor necrosis factor α (TNFα) were analyzed from the sampled organs. Adp−/− mice showed impaired glucose tolerance and insulin resistance. Additionally, PPARα levels were decreased and plasma concentration of triglyceride, FFA and TNFα were increased. These data may indicate that insulin resistance in Adp−/− mice is likely caused by an increase in concentrations of TNFα and FFA via downregulation of PPARα.

Adiponectin attenuates profibrotic extracellular matrix remodeling following cardiac injury by up-regulating matrix metalloproteinase 9 expression in mice.

Adiponectin (APN) is a multifunctional adipocytokine that inhibits myocardial fibrosis, dilatation, and left ventricular (LV) dysfunction after myocardial infarction (MI). Coxsackievirus B3 (CVB3) myocarditis is associated with intense extracellular matrix (ECM) remodeling which might progress to dilated cardiomyopathy. Here, we investigated in experimental CVB3 myocarditis whether APN inhibits adverse ECM remodeling following cardiac injury by affecting matrix metalloproteinase (MMP) expression. Cardiac injury was induced by CVB3 infection in APN knockout (APN‐KO) and wild‐type (WT) mice. Expression and activity of MMPs was quantified by qRT‐PCR and zymography, respectively. Activation of protein kinases was assessed by immunoblot. In cardiac myocytes and fibroblasts APN up‐regulates MMP‐9 expression via activation of 5′ adenosine monophosphate‐activated protein kinase (AMPK) and extracellular signal‐regulated kinase (ERK)1/2 which function as master regulators of inflammation‐induced MMP‐9 expression. Correspondingly, APN further increased up‐regulation of MMP‐9 expression triggered by tumor necrosis factor (TNF)α, lipopolysaccharide (LPS) and R‐848 in cardiac fibroblasts. In vivo, compared to WT mice cardiac MMP‐9 activity and serum levels of carboxy‐terminal telopeptide of type I collagen (ICTP) were attenuated in APN‐KO mice in subacute (day 7 p.i.) CVB3 myocarditis. Moreover, on day 3 and day 7 post CVB3 infection splenic MMP‐9 expression was diminished in APN‐KO mice correlating with attenuated myocardial immune cell infiltration in subacute CVB3 myocarditis. These results indicate that APN attenuates adverse cardiac remodeling following cardiac injury by up‐regulating MMP‐9 expression in cardiac and immune cells. Thus, APN mediates intensified collagen cleavage that might explain inhibition of LV fibrosis and dysfunction.

Erratum to: Inhibition of Angiotensin II-Induced Cardiac Fibrosis by Atorvastatin in Adiponectin Knockout Mice.

In the original published article, Victor Serebruany was designated as the corresponding author in error. The corresponding author is Jong Sung Park. Dr. Park can be reached by email at thinkmed@dau.ac.kr.

Suppression of adiponectin receptor 1 promotes memory dysfunction and Alzheimer\u2019s disease-like pathologies

Recent studies on neurodegeneration have focused on dysfunction of CNS energy metabolism as well as proteinopathies. Adiponectin (ADPN), an adipocyte-derived hormone, plays a major role in the regulation of insulin sensitivity and glucose homeostasis in peripheral organs via adiponectin receptors. In spite of accumulating evidence that adiponectin has neuroprotective properties, the underlying role of adiponectin receptors has not been illuminated. Here, using gene therapy-mediated suppression with shRNA, we found that adiponectin receptor 1 (AdipoR1) suppression induces neurodegeneration as well as metabolic dysfunction. AdipoR1 knockdown mice exhibited increased body weight and abnormal plasma chemistry and also showed spatial learning and memory impairment in behavioural studies. Moreover, AdipoR1 suppression resulted in neurodegenerative phenotypes, diminished expression of the neuronal marker NeuN, and increased expression and activity of caspase 3. Furthermore, AD-like pathologies including insulin signalling dysfunction, abnormal protein aggregation and neuroinflammatory responses were highly exhibited in AdipoR1 knockdown groups, consistent with brain pathologies in ADPN knockout mice. Together, these results suggest that ADPN-AdipoR1 signalling has the potential to alleviate neurodegenerative diseases such as Alzheimer’s diseases.

Abstract 123: Perivascular Adiponectin Attenuates the Neointimal Response Potentially via Modulation of Hydrogen Sulfide

Objective: Intimal hyperplasia (IH) limits the durability of vascular interventions. Perivascular adipose serves as scaffolding for vessels and also as a source of adipokines, including adiponectin (APN). The globular domain of adiponectin (gAPN) has high affinity for endothelial AdipoR1 receptors and holds beneficial roles in vascular adaptations. Hydrogen sulfide (H 2 S) is a vasculo-protective gasotransmitter produced by cystathionine γ-lyase (CGL), and low circulating H 2 S levels associate with human vascular disease. We therefore hypothesized that APN knockout (KO) mice would be predisposed to IH, and that local administration of gAPN would protect APN KO mice from IH. Furthermore, we evaluated potential links between APN and H 2 S in these effects. Approach and Results: Wildtype (WT, n=7) and APN KO (n=8) mice maintained on high fat diet were subject to carotid focal stenosis. An additional group of APN KO mice (n=7) were treated by local injection of gAPN suspended in Matrigel. Carotids were harvested 28 days following surgery and analyzed 400-2800μm proximal to the stenosis microscopically. IH area was significantly increased at 400μm in APN KO mice compared to WT (p=&lt;0.05, Fig. A), while gAPN significantly attenuated intimal area compared to untreated KO mice (p=&lt;0.05, Fig. B). This finding was coupled with significant (p=&lt;0.05, Fig. C) decrease in pre-operative baseline serum H 2 S production capacity in APN KO (lead acetate assay) compared to WT. Serum collected upon harvest trended toward increased H 2 S production capacity in APN KO mice treated with gAPN (Fig. D). Kidney CGL expression (Western) revealed a trend for increased in CGL expression in the gAPN group (Fig. E). Conclusion: In a focal stenosis model APN KO mice demonstrated increased distal IH; when administered locally, gAPN significantly attenuated IH. These data also uncover a reduction in H 2 S production capacity in APN KO mice, providing a novel potential link between these potent vasomediators.

Inhibition of Angiotensin II-Induced Cardiac Fibrosis by Atorvastatin in Adiponectin Knockout Mice.

Adiponectin is a polypeptide known to inhibit cardiac fibrosis via the activation of ‎adenosine monophosphate-activated protein kinase (AMPK). Statins can also activate AMPK, resulting in the secretion of adiponectin. We determined whether atorvastatin inhibits angiotensin II-induced cardiac fibrosis (AICF) in the presence or absence of adiponectin. Adiponectin knockout (APN-KO, n=44) and wild type (WT, n=44) mice were received subcutaneous angiotensin II (1.5mg/kg/day), and atorvastatin (10mg/kg/day) was administered orally for 15days. The mRNA expression levels of collagen type I and III, as well as AMPK phosphorylation levels in cardiac tissue were then measured. In the APN-KO mice, collagen type I (p<0.001) and type III (p=0.001) expression was significantly greater when treated with angiotensin II, while their expression was significantly reduced in the presence of angiotensin II and atorvastatin. Relative AMPK phosphorylation levels in APN-KO mice were also significantly higher in the angiotensin II+atorvastatin group when compared with angiotensin II group alone. We conclude that atorvastatin attenuates AICF independently from adiponectin by activating AMPK. These data suggest potential cardioprotection beyond lipid modulation potentially supporting statin pleiotropic hypothesis.

Adiponectin inhibits eosinophil recruitment and is protective in invasive aspergillosis

Abstract Aspergillus fumigatus is a fungal pathogen associated with allergy, asthma, and invasive infection in susceptible individuals. Our previous results suggested that eosinophils may be a novel therapeutic target in invasive aspergillosis (IA) patients that do not respond to conventional pharmacotherapy. Eosinophil recruitment is induced by inhalation of the fungal cell wall polysaccharide chitin. However, the mechanisms of immune regulation that drive this recruitment are not well understood. We observed decreased levels of the metabolic-regulating cytokine adiponectin in the lungs and serum of mice after chitin aspiration, suggesting that adiponectin may be involved in the regulation of type 2 lung immune responses. Co-aspiration of adiponectin with chitin significantly reduced eosinophil accumulation in the lungs, and airway eosinophil recruitment in adiponectin-deficient mice was increased with chitin aspiration. In addition, chitin aspiration resulted in decreased surface expression of the adiponectin receptor AdipoR1 on eosinophils. Most significantly, airway accumulation of eosinophils, disease severity, and fungal burden were increased in adiponectin knockout mice with IA. This may be due to a direct inhibition of eosinophil recruitment, as recombinant adiponectin inhibited chemotaxis of bone marrow-derived eosinophils in vitro. These results suggest that adiponectin inhibits potentially detrimental lung eosinophil recruitment in response to chitin-containing pathogens. Increased understanding of the relationship between metabolic and immune regulation may ultimately result in novel therapies for obesity and allergic and infectious disease.

Potential Therapeutic Action of Adiponectin in Duchenne Muscular Dystrophy

Adiponectin (ApN) is a hormone that exhibits anti-inflammatory effects on skeletal muscle exposed to acute and chronic inflammation. We have previously tested the implication of ApN in Duchenne muscular dystrophy (DMD) using mdx mice, a model of DMD, and by generating transgenic mdx mice overexpressing ApN. We showed that ApN can act as a preventive agent and delay disease progression by reducing muscle inflammation/injury and improving force/myogenesis. Herein, we took an opposite approach and crossed mdx mice with ApN knockout mice, to obtain mdx mice with ApN depletion. The aims were to test whether ApN deficiency could worsen the mdx phenotype and whether ApN supplementation can reverse several muscle abnormalities once the disease is settled. mdx-knockout mice exhibited lower muscle force/endurance as well as increased muscle damage when compared to regular mdx mice. Local administration of the ApN gene significantly reduced the expression of several oxidative stress/inflammatory markers and increased the expression of myogenic markers in the skeletal muscle. Finally, the presence of ApN markedly reduced the activity of NF-κB, a key player in muscle inflammation and myogenesis. ApN proves to be a powerful protector of the skeletal muscle capable of reversing the disease progression, thus making it a potential therapeutic agent for DMD.

Adiponectin confers protection from acute colitis and restricts a B cell immune response

Adiponectin demonstrates beneficial effects in various metabolic diseases, including diabetes, and in bowel cancer. Recent data also suggest a protective role in colitis. However, the precise molecular mechanisms by which adiponectin and its receptors modulate colitis and the nature of the adaptive immune response in murine models are yet to be elucidated. Adiponectin knock-out mice were orally administered dextran sulfate sodium for 7 days and were compared with wild-type mice. The severity of disease was analyzed histopathologically and through cytokine profiling. HCT116 colonic epithelial cells were employed to analyze the in vitro effects of adiponectin and AdipoR1 interactions in colonic injury following dextran sulfate sodium treatment. Adiponectin knock-out mice receiving dextran sulfate sodium exhibited severe colitis, had greater inflammatory cell infiltration, and an increased presence of activated B cells compared with controls. This was accompanied by an exaggerated proinflammatory cytokine profile and increased STAT3 signaling. Adiponectin knock-out mouse colons had markedly reduced proliferation and increased epithelial apoptosis and cellular stress. In vitro, adiponectin reduced apoptotic, anti-proliferative, and stress signals and restored STAT3 signaling. Following the abrogation of AdipoR1 in vitro, these protective effects of adiponectin were abolished. In summary, adiponectin maintains intestinal homeostasis and protects against murine colitis through interactions with its receptor AdipoR1 and by modulating adaptive immunity.

A novel mechanism of diabetic vascular endothelial dysfunction: Hypoadiponectinemia-induced NLRP3 inflammasome activation

It has been well documented that hypoadiponectinemia is associated with impaired endothelium-dependent vasodilation. However, the exact molecular mechanism which mediates this process has not been fully described. The current study aimed to investigate the role of hypoadiponectinemia-induced NLRP3 inflammasome activation in diabetic vascular endothelial dysfunction and its molecular mechanism. Male adult adiponectin knockout mice and wild type mice were fed with a high fat diet to establish a type 2 diabetic mellitus model. In addition, human umbilical vein endothelial cells (HUVECs) were cultured and subjected to high glucose/high fat (HG/HF). The NLRP3 inflammasome activation was increased in type 2 diabetic mice and treatment of diabetic aortic segments with MCC950, a potent selective inhibitor of NLRP3 inflammasome ex vivo improved endothelial-dependent vasorelaxation. NLRP3 inflammasome activation and vascular endothelial injury were significantly increased in APN-KO mice compared with WT mice in diabetes and MCC950 decreased diabetic vascular endothelial dysfunction to comparable levels in APN-KO mice and WT mice. Adiponectin could decrease NLRP3 inflammasome activation and attenuate endothelial cell injury, which was abolished by NLRP3 inflammasome overexpression. Inhibition of peroxynitrite formation preferentially attenuated NLRP3 inflammasome activation in APN-KO diabetic mice. The current study demonstrated for the first time that hypoadiponectinemia-induced NLRP3 inflammasome activation was a novel mechanism of diabetic vascular endothelial dysfunction.