Prevention of IL-6 signaling ameliorates toluene diisocyanate-induced steroid-resistant asthma.

BACKGROUND: Accumulating evidence indicated the crucial role for interleukin 6 (IL-6) signaling in the development of allergic asthma. Yet, the role of IL-6 signaling in toluene diisocyanate (TDI)-induced mixed granulocytic airway inflammation still remains unclear. Thus, the aims of this study were to dissect the role of IL-6 signaling and to evaluate the effect of tocilizumab on TDI-induced steroid-resistant asthma. METHODS: TDI-induced asthma model was prepared and asthmatic mice were respectively given IL-6 monoclonal antibody, IL-6R monoclonal antibody (tocilizumab, 5 mg/kg, i.p. after each challenge) for therapeutic purposes or isotype IgG as control. RESULTS: TDI exposure just elevated IL-6R expression in the infiltrated inflammatory cells around the airway, but increased glycoprotein 130 expression in the whole lung, especially in bronchial epithelium. Moreover, TDI inhalation increased airway hyperresponsiveness (AHR) to methacholine, coupled with mixed granulocytic inflammation, exaggerated epithelial denudation, airway smooth muscle thickening, goblet cell metaplasia, extensive submucosal collagen deposition, dysregulated Th2/Th17 responses, as well as innate immune responses and raised serum IgE. And almost all these responses except for raised serum IgE were markedly ameliorated by the administration of IL-6 neutralizing antibody or tocilizumab, but exhibited poor response to systemic steroid treatment. Also, TDI challenge induced nucleocytoplasm translocation of HMGB1 and promoted its release in the BALF, as well as elevated lung level of STAT3 phosphorylation, which were inhibited by anti-IL-6 and anti-IL-6R treatment. CONCLUSIONS: Our data suggested that IL-6 monoclonal antibody and tocilizumab might effectively abrogate TDI-induced airway inflammation and remodeling, which could be used as a clinical potential therapy for patients with severe asthma.

The effect of IL-6/Piezo2 on the trigeminal neuropathic pain.

The nature of trigeminal neuropathic pain (TN) attacks is regarded as the ignition of ectopic action potentials from the trigeminal root following vascular compression, which seemed to be related to transmembrane proteins and inflammation factors. This study focused on the mechanosensitive channel Piezo2 and cytokine IL-6. The chronic constriction injury of infraorbital nerve in SD rats was used to establish the TN model. The trigeminal ganglion was then achieved to perform immunocytochemistry studies. A significant upregulation of Piezo2 and IL-6 was showed in the TN model rats. The Piezo2 positive accounted for 72.3±9.5% in those IL-6 positive neurons. The Piezo2 co-localized with CGRP, IB4 and NF-200 but not with GFAP, which implied that it was expressed in both the C-type and the A-type neurons. After administration of GsMTx4 or anti-rat IL-6 antibody in the TN model, the dynamic allodynia and pinprick hyperalgesia scores as well as the mechanical threshold changed significantly. In the sham-operation rates, with local administration of IL-6, an upregulation of Piezo2 was also exhibited. Our study demonstrated that the up-regulation of Piezo2 in the pain afferent neurons following trigeminal nerve injury may play a role in the development of the neuralgia. Meanwhile, the expression of Piezo2 may be modulated by inflammatory cytokines, such as IL-6.

Pharmacological but not physiological GDF15 suppresses feeding and the motivation to exercise.

Growing evidence supports that pharmacological application of growth differentiation factor 15 (GDF15) suppresses appetite but also promotes sickness-like behaviors in rodents via GDNF family receptor α-like (GFRAL)-dependent mechanisms. Conversely, the endogenous regulation of GDF15 and its physiological effects on energy homeostasis and behavior remain elusive. Here we show, in four independent human studies that prolonged endurance exercise increases circulating GDF15 to levels otherwise only observed in pathophysiological conditions. This exercise-induced increase can be recapitulated in mice and is accompanied by increased Gdf15 expression in the liver, skeletal muscle, and heart muscle. However, whereas pharmacological GDF15 inhibits appetite and suppresses voluntary running activity via GFRAL, the physiological induction of GDF15 by exercise does not. In summary, exercise-induced circulating GDF15 correlates with the duration of endurance exercise. Yet, higher GDF15 levels after exercise are not sufficient to evoke canonical pharmacological GDF15 effects on appetite or responsible for diminishing exercise motivation.

Rebamipide promotes lacrimal duct epithelial cell survival via protecting barrier function.

Nasolacrimal duct obstruction (NLDO) is thought to be due to inflammation and fibrosis of lacrimal duct epithelial cells (LDECs). Here we investigated the effect of rebamipide, a drug that is used for the protection of the mucosa and the treatment of gastritis and gastroduodenal ulcers, on LDECs, both in vitro and in vivo. In this study, LDECs were cultured from rabbit lacrimal duct tissues, and the barrier function of LEDCs was examined in vitro via transepithelial electrical resistance (TER) measurement, with or without interleukin (IL)-6 and/or rebamipide. For the in vivo examination, benzalkonium chloride (BAC) was injected into the rabbit lacrimal ducts, followed by the application of rebamipide or a placebo vehicle alone. The results of the in vitro examination revealed a significant decrease in TER in the group treated with IL-6 alone compared with the placebo-vehicle group (p < 0.05) and the group treated with IL-6 and rebamipide (p < 0.01). The results of the in vivo examination revealed that the infiltration of neutrophils under the basement membrane and the disruption of tight junction proteins with BAC injection and rebamipide attenuates the disturbance of tissue construction. These results suggest that rebamipide protects LDECs via an anti-inflammatory effect and preserves the barrier function of those cells.

Effect of Holstein genotype on innate immune and metabolic responses of heifers to lipopolysaccharide (LPS) administration.

Heifers (n = 4/genotype) from unselected (stable genotype since 1964, UH) and contemporary (CH) Holsteins that differed in milk yield (6,200 and 11,100 kg milk/305 d) were used to assess the impact of selection on innate immune and acute-phase response to an endotoxin (lipopolysaccharide; LPS). Jugular catheters were implanted 24 h before LPS administration. Blood samples were collected at -1, -0.5, 0, 1, 2, 3, 4, 6, 8, and 24 h relative to iv administration of 0.5 µg LPS/kg BW. Rectal body temperature (BT) was determined at these sampling times and at 5 and 7 h. Dermal biopsies were collected after the 24 h blood sample and processed to isolate fibroblasts. Plasma was analyzed for tumor necrosis factor-alpha (TNF-α), interleukin-6 (IL-6), serum amyloid A (SAA), xanthine oxidase (XO), and nitrate + nitrite (NOx), cortisol, glucose, and IGF-1 content. Isolated fibroblasts were exposed to IL-1ß or LPS and IL-6 and IL-8 content of culture media determined. Exposure to LPS increased BTs and plasma concentrations of TNF-α, IL-6 SAA, XO, cortisol, and glucose (P < 0.05) in both genotypes. Plasma concentrations of TNF-α, XO, NOx, and glucose did not differ (P > 0.25) between the genotypes, but IL-6 and SAA concentrations were reduced (P < 0.05) in CH relative to UH heifers while cortisol and IGF-1 concentrations tended (P < 0.08) to be reduced in CH heifers. After 36 h exposure to LPS, concentrations of IL-6 were greater (P < 0.05) in culture media from incubations of CH than UH fibroblasts but concentrations of IL-8 did not differ between genotypes. There was a trend (P = 0.08) for IL-8 concentrations to be reduced in media from CH fibroblasts exposed to IL-1ß for 24 h but IL-6 concentrations did not differ between genotypes. Results indicate 50 yr of selection has reduced the robustness of the innate immune and acute-phase response to LPS in the contemporary Holstein heifer.

Interleukin-6 selectively induces drug metabolism to potentiate the genotoxicity of dietary carcinogens in mammary cells.

Breast cancer is the most commonly diagnosed malignancy in females, the etiology being multifactorial and includes the role of lifestyle exposure to DNA-damaging chemicals such as dietary carcinogens benzo (a) pyrene (BaP) and 2-amino-1-methyl-6-phenylimidazo [4, 5-b] pyridine (PhIP). Both compounds require cytochrome P450 (CYP)-mediated metabolic activation to DNA-damaging species, and both induce transcriptional responses through the nuclear receptors Aryl hydrocarbon receptor (AhR) and estrogen receptor α (ERα). BaP and PhIP are mammary carcinogens in rodents. Clinically, circulating IL-6 expression is linked with poor prognosis of cancer and 35% of the deaths in breast cancer are linked with inflammation. The objective of this work was to investigate the molecular toxicology and local activation of BaP and PhIP in the presence of IL-6. Our laboratory has previously reported that miR27b can regulate CYP1B1 expression in colorectal cells, here we have investigated if this mechanism is working in mammary cell models, MCF-7 and MDA-MB-231 cells. Treatment (24 h) of cells with BaP (10 nM-10 µM) and PhIP (100 nM-100 µM) significantly induced genetic damage (micronuclei formation) in a dose-dependent manner in both cell lines. This effect was potentiated in the presence of human IL-6 at concentrations reported to be expressed in clinical breast cancer. On its own, IL-6 treatment failed to induce micronuclei frequency above the control levels in these cells. Compared to BaP or PhIP treatment alone, IL-6 plus BaP or PhIP selectively induced CYP1B1 significantly in both cell lines. Additionally, miR27b expression was downregulated by IL-6 treatments and transfection with miR27b inhibitor confirmed that miR27b is a regulator of CYP1B1 in both cell lines. These data show that BaP- and PhIP-induced DNA damage in mammary cells is potentiated by the inflammatory cytokine IL-6 and that inflammation-induced CYP expression, specifically CYP1B1 via miR27b, is responsible for this effect.

IL-6 Impairs the Activity of Vitamin D3 in the Regulation of Epithelial-Mesenchymal Transition in Triple Negative Breast Cancer.

Objective: The present study aimed to investigate the possible role of IL-6 and 1α,25-dihydroxyvitamin D3 (1,25D) signaling in epithelial-mesenchymal transition (EMT) and stemness in triple-negative breast cancer (TNBC) cell line. Methods: TNBC cell line, HCC 1806, was treated with IL-6 and 1,25D for three and six days. Also, the role of vitamin D receptor (VDR) was studied by transfection of TNBC cell line with VDR gene and transfection efficiency was assessed using Human VDR enzyme-linked immunosorbent assay (ELISA). Changes in E-cadherin gene expression were analyzed by quantitative real-time PCR (qRT-PCR). Also, changes in CD44+ cells were analyzed by flow cytometry. Finally, morphological changes were investigated by light microscopy after 6 days. Results: Treatment of HCC1806 cells with IL-6 has no significant effect either on E-cadherin gene expression or CD44+ cells, (p > 0.05). However, E-cadherin gene expression was significantly up-regulated after treatment with 1,25D for 6 days, (p < 0.05). Also, CD44+ cells were significantly reduced after treatment with 1,25D either for 3 or 6 days, (p < 0.05). Transfection of TNBC cell line with VDR gene significantly up-regulated VDR protein expression, (p < 0.05). In addition, overexpression of VDR in TNBC cells and treatment with 1,25D significantly up-regulated E-cadherin gene expression, (p < 0.05) and reduced CD44+ cells, (p < 0.05). Moreover, transfection with VDR and treatment with a combination of 1,25D and IL-6 significantly down-regulated E-cadherin gene expression and increased CD44+ cells compared with transfected cells with VDR treated with 1,25D alone, (p < 0.05). No significant morphological changes were observed in treated cells, 6 days post-treatment. Conclusion: The presence of IL-6 in the breast tumor microenvironment may impair the activity of vitamin D3 signaling, limiting its anti-tumor effects in TNBC.

Noncoding dsRNA induces retinoic acid synthesis to stimulate hair follicle regeneration via TLR3.

How developmental programs reactivate in regeneration is a fundamental question in biology. We addressed this question through the study of Wound Induced Hair follicle Neogenesis (WIHN), an adult organogenesis model where stem cells regenerate de novo hair follicles following deep wounding. The exact mechanism is uncertain. Here we show that self-noncoding dsRNA activates the anti-viral receptor toll like receptor 3 (TLR3) to induce intrinsic retinoic acid (RA) synthesis in a pattern that predicts new hair follicle formation after wounding in mice. Additionally, in humans, rejuvenation lasers induce gene expression signatures for dsRNA and RA, with measurable increases in intrinsic RA synthesis. These results demonstrate a potent stimulus for RA synthesis by non-coding dsRNA, relevant to their broad functions in development and immunity.

Interleukin-6 Therapy Improves Intestinal Recovery Following Ischemia.

BACKGROUND: Interleukin-6 (IL6) has both proinflammatory and anti-inflammatory pathways, but its effects on intestinal recovery following ischemia are unknown. We hypothesized that administration of IL6 following intestinal ischemia would improve mesenteric perfusion and mucosal injury. METHODS: Adult male C57Bl6J mice were anesthetized, and a laparotomy was performed. Baseline intestinal perfusion was assessed by laser Doppler imaging. Intestinal ischemia was induced for 60 min by temporarily occluding the superior mesenteric artery. After ischemia, treatments were administered intraperitoneally before closure (Vehicle: 250 µL phosphate-buffered-saline, IL6 low dose (20 ng), IL6 medium dose (200 ng), or IL6 high dose (2 µg)). Animals were allowed to recover for 24 h, were reanesthetized, and their mesenteric perfusion was reassessed. Perfusion was expressed as percentage of baseline. Animals were then sacrificed, and the intestines were explanted for histological analysis. Separate frozen samples were homogenized and analyzed by ELISA for vascular endothelial growth factor (VEGF) and interferon gamma-induced protein 10. RESULTS: IL6 increased mesenteric perfusion in low dose groups only, whereas it improved postischemic mucosal injury scores in both low and medium dose groups. No differences in perfusion or histology were seen when high dose IL6 was utilized. Intestinal VEGF was higher in the low dose IL6 group compared to vehicle, whereas IP-10 levels were lower in low and medium dose groups compared to vehicle. No differences were noted compared to vehicle in intestinal VEGF and IP-10 with high dose IL6 therapy. CONCLUSIONS: Lower doses of IL6 may serve as effective therapy to decrease intestinal injury after ischemia. Further studies are needed to elucidate the downstream mechanisms before widespread clinical use.

In vivo effect of acute exposure to interleukin-6 on the developing visual system.

Interleukin-6 (IL-6) is involved in different processes of the central nervous system. Our aims were to investigate the effect of IL-6 on retinotectal topography and on different signaling pathways. Rats were submitted to an intravitreous injection of either IL-6 (50 ng/ml) or PBS (vehicle) at postnatal day 10 (PND10). At PND11 or PND14, different groups were processed for western blot, histochemistry or immunofluorescence analysis. IL-6 treatment leads to an increase in pSTAT-3 levels in the retina and a disruption in the retinotectal topographic map, suggesting that a transient increase in interleukin-6 levels may impact neural circuitry development.

STAT3 is involved in IL-6-Mediated Downregulation of Hepatic Transporters in Mice.

Interleukin (IL)-6 decreases hepatic expression of numerous transporters. Although IL-6 signaling occurs through STAT3, the extent of the involvement of the STAT3 signaling pathway has not been elucidated. PURPOSE: Our objective was to investigate whether IL-6-mediated effects occur through STAT3, and whether PXR plays a role in this regulation. METHOD: PXR null (-/-) or wild-type (+/+) male mice were pre-dosed with a selective STAT3 inhibitor S3I-201 (7.5 mg/kg ip) or vehicle (n=5-8/group) 30 minutes before receiving a single dose of IL-6 (1 µg ip) or saline. Animals were sacrificed after 6 hours and liver samples were analyzed using qRT-PCR and western blotting. RESULTS: As compared to saline controls, IL-6 decreased the expression of Cyp3a, Abcb1a, Abcc3, and Slco1a4 20-70% similarly in PXR (+/+) and (-/-) mice at 6 hr, while downregulation of Abcb11, Abcc2, Slc10a1and Slco2b1 was only seen in PXR (+/+). Pre-administration of S3I-201 attenuated IL-6-mediated changes of most transporters in PXR (+/+) and PXR (-/-) mice. At early times after IL-6 administration (10-120 minutes), transcript levels of Socs3, PXR, Abcb1a, Abcc3, Abcb11, Slco1a4 and Slco2b1were increased in PXR (+/+) mice. CONCLUSIONS: Our findings demonstrate that IL-6 imposes a significant downregulation of numerous ABC and SLC transporters in liver primarily through activation of the STAT3 signaling pathway. Based on time-dependent changes in transporter expression, downregulation likely occurs downstream of STAT3 activation.  As IL-6 is elevated in many diseases, understanding the underlying mechanism(s) involved in transporter dysregulation will allow us to predict potential drug-disease interactions.

Matrix metalloproteinase promotes elastic fiber degradation in ligamentum flavum degeneration.

Ligamentum flavum (LF) hypertrophy in lumbar spinal canal stenosis (LSCS) is characterized by a loss of elastic fibers and fibrosis. Chronic inflammation is thought to be responsible for the histological change but the mechanism underlying elastic fiber degradation remains unclear. Given that matrix metalloproteinase (MMP)-2 and -9 have elastolytic activity and are partly regulated by inflammatory cytokines such as interleukin (IL)-6, in this study, we investigated whether MMPs mediate LF degeneration using 52 LF samples obtained during lumbar surgery, including 31 LSCS and 21 control specimens. We confirmed by histological analysis that the LSCS samples exhibited severe degenerative changes compared with the controls. We found that MMP-2 was upregulated in LF tissue from patients with LSCS at the mRNA and protein levels, whereas MMP-9 expression did not differ between the two groups. The MMP-2 level was positively correlated with LF thickness and negatively correlated with the area occupied by elastic fibers. IL-6 mRNA expression was also increased in LF tissue from patients with LSCS and positively correlated with that of MMP-2. Signal transducer and activator of transcription (STAT)3, a component of the IL-6 signaling pathway, was activated in hypertrophied LF tissues. Our in vitro experiments using fibroblasts from LF tissue revealed that IL-6 increased MMP-2 expression, secretion, and activation via induction of STAT3 signaling, and this effect was reversed by STAT3 inhibitor treatment. Moreover, elastin degradation was promoted by IL-6 stimulation in LF fibroblast culture medium. These results indicate that MMP-2 induction by IL-6/STAT3 signaling in LF fibroblasts can degrade elastic fibers, leading to LF degeneration in LSCS.

Exercise activates the hypothalamic S1PR1-STAT3 axis through the central action of interleukin 6 in mice.

Hypothalamic sphingosine-1-phosphate receptor 1 (S1PR1), the G protein-coupled receptor 1 of sphingosine-1-phosphate, has been described as a modulator in the control of energy homeostasis in rodents. However, this mechanism is still unclear. Here, we evaluate the role of interleukin 6 (IL-6) associated with acute physical exercise in the control of the hypothalamic S1PR1-signal transducer and activator of transcription 3 (STAT3) axis. Acute exercise session and an intracerebroventricular IL-6 injection increased S1PR1 protein content and STAT3 phosphorylation in the hypothalamus of lean and obese mice accompanied by a reduction in food consumption. Transcriptome analysis indicated a strong positive correlation between Il-6 and S1pr1 messenger RNA in several tissues of genetically diverse BXD mice strains and humans, including in the hypothalamus. Interestingly, exercise failed to stimulate the S1PR1-STAT3 axis in IL-6 knockout mice and the disruption of hypothalamic-specific IL-6 action blocked the anorexigenic effects of exercise. Taken together, our results indicate that physical exercise modulates the S1PR1 protein content in the hypothalamus, through the central action of IL-6.

Acute administration of interleukin-6 does not increase secretion of glucagon-like peptide-1 in mice.

Interleukin 6 (IL-6) is a cytokine secreted from skeletal muscle in response to exercise which, based on animal and cell studies, has been suggested to contribute to glucose metabolism by increasing secretion of the incretin hormone glucagon-like peptide-1 (GLP-1) and affecting secretion of insulin and glucagon from the pancreatic islets. We investigated the effect of IL-6 on GLP-1 secretion in GLP-1 producing cells (GLUTag) and using the perfused mouse small intestine (harboring GLP-1 producing cells). Furthermore, the direct effect of IL-6 on insulin and glucagon secretion was studied using isolated perfused mouse pancreas. Incubating GLUTag cells with 1000 ng/mL of IL-6 for 2 h did not significantly increase secretion of GLP-1 whereas 10 mmol/L glucose (positive control) did. Similarly, IL-6 (100 ng/mL) had no effect on GLP-1 secretion from perfused mouse small intestine whereas bombesin (positive control) increased secretion. Finally, administering IL-6 (100 ng/mL) to perfused mouse pancreases did not significantly increase insulin or glucagon secretion regardless of perfusate glucose levels (3.5 vs. 12 mmol/L glucose). Acute effects of IL-6 therefore do not seem to include a stimulatory effect on GLP-1 secretion in mice.

The synergistic effects of IL-6/IL-17A promote osteogenic differentiation by improving OPG/RANKL ratio and adhesion of MC3T3-E1 cells on hydroxyapatite.

OBJECTIVE: In this study, we evaluated the potential role of IL-6 and/or IL-17A in regulating the OPG/RANKL (osteoprotegerin/receptor activator of nuclear factor kappa b ligand) system of murine osteoblast cell line (MC3T3-E1) cultured on hydroxyapatite (HA). METHODS: MC3T3-E1 cells were seeded on HA and treated with recombinant IL-6 or rIL-17A or combination of the two cytokines. Cell proliferation and differentiation activity were measured by MTS and alkaline phosphatase assays respectively. Observation of cell adhesion and proliferation was examined by scanning electron microscopy. Gene and protein expressions were performed on RANKL and OPG using qPCR, Western blot and ELISA. RESULTS: We demonstrated that treatment with recombinant IL-17A (rIL-17A) and the combination rIL-6/rIL-17A promoted better adhesion and higher proliferation of cells on HA. Cells treated with rIL-17A and the combination cytokines showed a significant increase in differentiation activity on day 7, 10 and 14 as indicated by ALP activity (p < 0.001). Gene and protein expressions showed significant up-regulation of OPG and ALP (p < 0.001) and down-regulation of RANKL (p < 0.001) expression by all the treated groups. Interestingly, the combination of the two cytokines resulted in a significant increase of OPG/RANKL ratio (p < 0.001). CONCLUSION: These findings indicated that treatment with the combination of the two cytokines (IL-6/IL-17A) has synergistic effects to promote osteoblastic differentiation but suppress osteoclastogenesis by altering the OPG/RANKL ratio.

Interleukin-6 Delays Gastric Emptying in Humans with Direct Effects on Glycemic Control.

Gastric emptying is a critical regulator of postprandial glucose and delayed gastric emptying is an important mechanism of improved glycemic control achieved by short-acting glucagon-like peptide-1 (GLP-1) analogs in clinical practice. Here we report on a novel regulatory mechanism of gastric emptying in humans. We show that increasing interleukin (IL)-6 concentrations delays gastric emptying leading to reduced postprandial glycemia. IL-6 furthermore reduces insulin secretion in a GLP-1-dependent manner while effects on gastric emptying are GLP-1 independent. Inhibitory effects of IL-6 on gastric emptying were confirmed following exercise-induced increases in IL-6. Importantly, gastric- and insulin-reducing effects were maintained in individuals with type 2 diabetes. These data have clinical implications with respect to the use of IL-6 inhibition in autoimmune/inflammatory disease, and identify a novel target that could be exploited pharmacologically to delay gastric emptying and spare insulin, which may be beneficial for the beta cell in type 2 diabetes.

Resveratrol inhibits Interleukin-6 induced invasion of human gastric cancer cells.

Previous studies show that migration and invasion are the primary causes of death in patients with gastric carcinoma. Increasing evidences have been shown Interleukin-6 could stimulate cancer cells invasion and be associated with cancer development. However, its role in gastric cancer has never been investigated. As an anticancer drug isolated from Chinese medicine, resveratrol was reported to inhibit cancer cells growth and induce apoptosis, but its roles in gastric cancer have not been well understood. In this study, we found that Interleukin-6 was upregulated in blood of gastric cancer patients by enzyme-linked immunosorbent assay. In gastric cancer cell line model, we found that non-cytotoxic concentration of resveratrol inhibited the Interleukin-6 induced SGC7901 cell invasion and matrix metalloproteinases activation. Our studies showed that IL-6 induced SGC7901 cell invasion depends on the Raf/MAPK pathway activation, resveratrol could inhibit this pathway activation. We further showed that resveratrol inhibits the IL-6 induced metastasis by vein injection of luciferase-labeled cancer cells. In conclusion, these results indicate that Interleukin-6 promotes tumor growth and metastasis in gastric cancer, resveratrol has the potential to prevent the Interleukin-6 induced gastric cancer metastasis by blocking the Raf/MAPK signaling activation.

Peptide YY Causes Apathy-Like Behavior via the Dopamine D2 Receptor in Repeated Water-Immersed Mice.

Apathy is observed across several neurological and psychiatric conditions; however, its pathogenesis remains unclear. We clarified the involvement of brain-gut signaling in the disruption of goal-directed behavior. Male C57BL/6J mice were exposed to water immersion (WI) stress for 3 days. Food intake and nesting behavior were measured as indexes of motivation. Repeated WI caused decrease in food intake and nesting behavior. Plasma levels of peptide YY (PYY), IL-6, and ratio of dopamine metabolites in the striatum were significantly elevated after WI. PYY and IL-6 administration significantly decreased nesting behavior. The reductions in feeding and nesting behavior were blocked by PYY receptor (Y2R) antagonist or dopamine agonist. The ameliorative effect of the Y2R antagonist was diminished by the dopamine D2 receptor (D2R) antagonist. The reduction in goal-directed behavior is associated with dysfunction of D2R signaling via increased peripheral PYY, suggesting that PYY antagonism is a novel candidate for decline of motivation in several depressive diseases.

Primary Cilia Are Dysfunctional in Obese Adipose-Derived Mesenchymal Stem Cells.

Adipose-derived mesenchymal stem cells (ASCs) have crucial functions, but their roles in obesity are not well defined. We show here that ASCs from obese individuals have defective primary cilia, which are shortened and unable to properly respond to stimuli. Impaired cilia compromise ASC functionalities. Exposure to obesity-related hypoxia and cytokines shortens cilia of lean ASCs. Like obese ASCs, lean ASCs treated with interleukin-6 are deficient in the Hedgehog pathway, and their differentiation capability is associated with increased ciliary disassembly genes like AURKA. Interestingly, inhibition of Aurora A or its downstream target the histone deacetylase 6 rescues the cilium length and function of obese ASCs. This work highlights a mechanism whereby defective cilia render ASCs dysfunctional, resulting in diseased adipose tissue. Impaired cilia in ASCs may be a key event in the pathogenesis of obesity, and its correction might provide an alternative strategy for combating obesity and its associated diseases.

Enhancement of immune response of piglets to PCV-2 vaccine by porcine IL-2 and fusion IL-4/6 gene entrapped in chitosan nanoparticles.

In order to develop a novel effective immunomodulator to enhance pig resistance against post-weaning multi systemic wasting syndrome (PMWS), a recombinant plasmid co-expressing pig interleukin-2 (IL-2) and fusion interleukin-4/6 (IL-4/6) genes, designated VRIL4/6-2, was constructed and encapsulated in chitosan (CS) nanoparticles prepared by the ionotropic gelation method. Then 21-day old piglets were divided into two groups and intramuscularly injected respectively with VPIL4/6-2-CS and saline along with the porcine circovirus-2 (PCV-2) vaccine. The blood was collected from each piglet on days 0, 7, 14, 28, 56 and 84 after vaccination to assay the immunological changes. Content of IgG2a, CD4+, CD8+ T cells increased significantly in the sera or blood of piglets treated with VPIL4/6-2-CS (P<0.05). Furthermore, the expression level of IL-2, IL-4, IL-6, IL-15, TLR-2, TLR-7, Bcl-2, TNF-α, CD45 and STATs (STAT1, STAT2, STAT3, STAT4) genes were significantly elevated in the treated piglets respectively in different days after inoculation (P<0.05). The growth weight gain of the treated piglets was markedly improved in comparison with the controls (P<0.05). These indicate that VPIL-4/6-2 entrapped with chitosan nanoparticles is a safe and promising effective adjuvant to promote the immune response of pig to PCV-2 vaccination.