Vasoactive Intestinal Peptide Knockout Mice Research Articles

Vasoactive intestinal peptide deficiency promotes ovarian dysfunction associated to a proinflammatory microenvironment reminiscent of premature aging

Complex immune regulation during pregnancy is required to ensure a successful pregnancy outcome. Vasoactive intestinal peptide (VIP) has local immunoregulatory effects on the ovary, uterus and maternal-fetal interface that favor a tolerogenic maternal microenvironment. Since the VIP Knockout (KO) mice are subfertile, we investigated the mechanisms underlying the effects of VIP deficiency on ovarian physiology and immune homeostasis. Therefore, we studied VIP KO, deficient (HT) and wild type (WT) female mice in estrus at 3 or 8 months of age. Young KO mice showed abnormal cycle timing and regularity associated with dysfunctional ovaries. Ovaries presented higher number of atretic follicles and reduced number of corpora lutea leading to a lower ovulation rates. Part of the VIP KO mice (25 %) failed to ovulate or ovulated oocytes incompetent to be fertilized (50 %). In particular, ovaries of young KO mice exhibited features of premature aging accompanied by a pro-inflammatory milieu with increased levels of IL-1β. A unique macrophage subpopulation identified as “foamy macrophages” was found. On the other hand, aged VIP KO females did not gain body weight probably due to the sustained production of E2. Finally, the adoptive transfer of FOXP3+ cells to infertile VIP KO females resulted in their selective recruitment to the ovary. It increased FOXP3/RORγt and TGFβ/IL-6 ratio improving ovarian microenvironment and pregnancy rate. The present results suggest that VIP contributes to ovarian homeostatic mechanisms required for a successful pregnancy.

Enhanced Mortality to Metastatic Bladder Cancer Cell Line MB49 in Vasoactive Intestinal Peptide Gene Knockout Mice.

To identify if the absence of the vasoactive intestinal peptide (VIP) gene enhances susceptibility to death from metastatic bladder cancer, two strains of mice were injected with MB49 murine bladder cancer cells. The growth and spread of the cancer was measured over a period of 4 weeks in C57BL/6 mice and 5 weeks in VIP knockout (KO) mice. A Kaplan–Meier plot was constructed to compare control C57BL/6 mice and C57BL/6 mice with MB49 vs. VIP KO controls and VIP KO mice with MB49. The wild-type (WT) strain (C57BL/6) contained the VIP gene, while the other strain, VIP knockout backcrossed to C57BL/6 (VIP KO) did not and was thus unable to endogenously produce VIP. VIP KO mice had increased mortality compared to C57BL/6 mice at 4 weeks. The number of ulcers between both groups was not statistically significant. In vitro studies indicated that the presence VIP in high doses reduced MB49 cell growth, as well as macrophage inhibitory factor (MIF), a growth factor in bladder cancer cells. These findings support the concept that VIP may attenuate susceptibility to death from bladder cancer, and that it exerts its effect via downregulation of MIF.

Emerging Novel Therapies for Heart Failure.

Heart function fails when the organ is unable to pump blood at a rate proportional to the body’s need for oxygen or when this function leads to elevated cardiac chamber filling pressures (cardiogenic pulmonary edema). Despite our sophisticated knowledge of heart failure, even so-called ejection fraction-preserved heart failure has high rates of mortality and morbidity. So, novel therapies are sorely needed. This review discusses current standard therapies for heart failure and launches an exploration into emerging novel treatments on the heels of recently-approved sacubitril and ivbradine. For example, Vasoactive Intestinal Peptide (VIP) is protective of the heart, so in the absence of VIP, VIP knockout mice have dysregulation in key heart failure genes: 1) Force Generation and Propagation; 2) Energy Production and Regulation; 3) Ca+2 Cycling; 4) Transcriptional Regulators. VIP administration leads to coronary dilation in human subjects. In heart failure patients, VIP levels are elevated as a plausible endogenous protective effect. With the development of elastin polymers to stabilize VIP and prevent its degradation, VIP may therefore have a chance to satisfy the unmet need as a potential treatment for acute heart failure.

Cystic fibrosis transmembrane conductance regulator dysfunction in VIP knockout mice.

Vasoactive intestinal peptide (VIP), a neuropeptide, controls multiple functions in exocrine tissues, including inflammation, and relaxation of airway and vascular smooth muscles, and regulates CFTR-dependent secretion, which contributes to mucus hydration and local innate defense of the lung. We had previously reported that VIP stimulates the VPAC1 receptor, PKCϵ signaling cascade, and increases CFTR stability and function at the apical membrane of airway epithelial cells by reducing its internalization rate. Moreover, prolonged VIP stimulation corrects the molecular defects associated with F508del, the most common CFTR mutation responsible for the genetic disease cystic fibrosis. In the present study, we have examined the impact of the absence of VIP on CFTR maturation, cellular localization, and function in vivo using VIP knockout mice. We have conducted pathological assessments and detected signs of lung and intestinal disease. Immunodetection methods have shown that the absence of VIP results in CFTR intracellular retention despite normal expression and maturation levels. A subsequent loss of CFTR-dependent chloride current was measured in functional assays with Ussing chamber analysis of the small intestine ex vivo, creating a cystic fibrosis-like condition. Interestingly, intraperitoneal administration of VIP corrected tissue abnormalities, close to the wild-type phenotype, as well as associated defects in the vital CFTR protein. The results show in vivo a primary role for VIP chronic exposure in CFTR membrane stability and function and confirm in vitro data.

VIP Gene Deletion in Mice Causes Cardiomyopathy Associated with Upregulation of Heart Failure Genes

RationaleVasoactive Intestinal Peptide (VIP), a pulmonary vasodilator and inhibitor of vascular smooth muscle proliferation, is absent in pulmonary arteries of patients with idiopathic pulmonary arterial hypertension (PAH). We previously determined that targeted deletion of the VIP gene in mice leads to PAH with pulmonary vascular remodeling and right ventricular (RV) dilatation. Whether the left ventricle is also affected by VIP gene deletion is unknown. In the current study, we examined if VIP knockout mice (VIP−/−) develop both right (RV) and left ventricular (LV) cardiomyopathy, manifested by LV dilatation and systolic dysfunction, as well as overexpression of genes conducive to heart failure.MethodsWe examined VIP−/−and wild type (WT) mice using Magnetic Resonance Imaging (MRI) for evidence of cardiomyopathy associated with biventricular dilation and wall thickness changes. Lung tissue from VIP−/− and WT mice was subjected to whole-genome gene microarray analysis.ResultsLungs from VIP−/− mice showed overexpression of cardiomyopathy genes: Myh1 was upregulated 224 times over WT, and Mylpf was increased 72 fold. Tnnt3 was increased 105 times and tnnc2 181 fold. Hearts were dilated in VIP−/− mice, with thinning of LV wall and increase in RV and LV chamber size, though RV enlargement varied. Weights of VIP−/− mice were consistently lower.ConclusionsCritically-important heart failure-related genes are upregulated in VIP−/− mice associated with the spontaneous cardiomyopathy phenotype, involving both left and right ventricles, suggesting that loss of the VIP gene orchestrates a panoply of pathogenic genes which are detrimental to both left and right cardiac homeostasis.

Role of vasoactive intestinal peptide in seasonal encoding by the suprachiasmatic nucleus clock

The neuropeptide vasoactive intestinal peptide (VIP) is critical for the proper functioning of the neural circuit that generates circadian rhythms. Mice lacking VIP show profound deficits in the ability to generate many behavioral and physiological rhythms. To explore how the loss of VIP impacts on the intact circadian system, we carried out in vivo multiunit neural activity (MUA) recordings from the suprachiasmatic nucleus of freely moving VIP knockout (KO) mice. The MUA rhythms were largely unaltered in the VIP KO mice, with no significant differences being seen in the amplitude or phase of the rhythms in light-dark conditions. Robust differences between the genotypes were revealed when the mice were transferred from light-dark to constant darkness conditions. In addition, the ability of the VIP KO mice to encode changes in photoperiod was examined. Strikingly, the behavioral and physiological rhythms of VIP KO mice showed no adaptation to short or long photoperiods. The data indicate that the intact circadian system can compensate for some of the consequences of the loss of VIP, whereas this peptide is indispensable for endogenous encoding of seasonal information.

Vasoactive Intestinal Peptide Knockout (VIP KO) mouse model of sulfite-sensitive asthma: up-regulation of novel lung carbonyl reductase

BackgroundWe earlier reported spontaneous features of asthma in Vasoactive Intestinal Peptide knockout mice (VIP KO): 1) peribronchiolar airway inflammation, with accumulation of lymphocytes and eosinophils, 2) pro-inflammatory cytokine production of IL-5, IL-6, with IFN-γ, and 3) airway hyper-responsiveness to inhaled methacholine. In human asthma, a phenotype with sulfite sensitivity leads to airway inflammation and hyper-responsiveness to inhaled sulfites, and is associated with upregulation of anti-oxidant protein lung carbonyl reductase. For the present experiments, we examined the role of VIP in modulating anti-oxidant genes and their proteins, including lung carbonyl reductase.ResultsFour male VIP KO mice and four wild-type age- and gender matched mice had lungs examined for whole genome microarray and a proteomics approach using mass spectrometry. The proteomics analysis revealed that a novel variant of anti-oxidant protein lung carbonyl reductase (car3) was uniquely and markedly elevated in the VIP KO mice. RT-PCR indicated that carbonic anhydrase 3, which is an anti-oxidant protein, was elevated in the VIP KO mice.ConclusionsThese data support the concept that VIP influences the endogenous oxidant/antioxidant balance. One potential implication is that VIP and its analogues may be used to treat inflammatory diseases, including asthma.

Vasoactive Intestinal Peptide–Null Mice Demonstrate Enhanced Sweet Taste Preference, Dysglycemia, and Reduced Taste Bud Leptin Receptor Expression

OBJECTIVEIt is becoming apparent that there is a strong link between taste perception and energy homeostasis. Recent evidence implicates gut-related hormones in taste perception, including glucagon-like peptide 1 and vasoactive intestinal peptide (VIP). We used VIP knockout mice to investigate VIP's specific role in taste perception and connection to energy regulation.RESEARCH DESIGN AND METHODSBody weight, food intake, and plasma levels of multiple energy-regulating hormones were measured and pancreatic morphology was determined. In addition, the immunocytochemical profile of taste cells and gustatory behavior were examined in wild-type and VIP knockout mice.RESULTSVIP knockout mice demonstrate elevated plasma glucose, insulin, and leptin levels, with no islet β-cell number/topography alteration. VIP and its receptors (VPAC1, VPAC2) were identified in type II taste cells of the taste bud, and VIP knockout mice exhibit enhanced taste preference to sweet tastants. VIP knockout mouse taste cells show a significant decrease in leptin receptor expression and elevated expression of glucagon-like peptide 1, which may explain sweet taste preference of VIP knockout mice.CONCLUSIONSThis study suggests that the tongue can play a direct role in modulating energy intake to correct peripheral glycemic imbalances. In this way, we could view the tongue as a sensory mechanism that is bidirectionally regulated and thus forms a bridge between available foodstuffs and the intricate hormonal balance in the animal itself.

The Absence of Vasoactive Intestinal Peptide Augments Allo-Reactivity and the Anti-Viral Response in Bone Marrow Transplantation.

Background: The severe morbidity and mortality associated with bone marrow transplantation (BMT) is caused by uninhibited immune responses to alloantigen and suppressed immune responses to pathogens. Vasoactive Intestinal Peptide (VIP) is an immunomodulatory neuropeptide produced by T-cells and nerve fibers in peripheral lymphoid organs that suppresses immune responses by induction of tolerogenic dendritic cells. In order to determine the immunoregulatory effects of VIP, we examined T-cell immune responses to allo- and viral-antigens in VIP knockout (KO) mice and mouse BMT recipients of hematopoietic cells from VIP KO donors.Methods: VIP KO mice and VIP WT littermates were infected with lethal or sub-lethal doses (5 × 104− 5 × 105 PFU) of murine cytomegalovirus (mCMV) and the T-cell response to viral antigen was measured by flow cytometry for mCMV peptide-MHC class 1-tetramer+ CD8+ T-cells. We transplanted 5 × 106 BM plus 1 × 106 splenocytes (SP) either from VIP KO or VIP WT donors in an C57BL/6 to F1(BL/6 × Balb/c) allo-BMT model and assessed survival, GvHD, donor T-cell expansion, chimerism, and response to mCMV vaccination and mCMV infection.Results: B-cell, αβ and γδ T-cell, CD8+ T-cell, CD11b+ myeloid cell, and dendritic cell numbers were equivalent between VIP KO and WT mice, while VIP KO mice had higher number of CD4+ and CD4+CD62L+CD25+ T-cells. Non-transplanted VIP KO mice survived mCMV infection better compared to VIP WT, with a brisker anti-viral T-cell response in the blood. In the allogeneic BMT setting, recipients of VIP KO BM plus VIP KO SP had more weight loss and lower (40%) 100 day post-transplant survival compared to the recipients of VIP KO BM plus WT SP (80% survival), recipients of WT BM plus KO SP (100% survival), and recipients of WT BM plus WT SP (80% survival). Recipients of VIP KO grafts had a significantly greater anti-mCMV response that peaked four days earlier than the tetramer response of mice transplanted with WT cells. This increased anti-viral response to vaccination correlated with a greater and more rapid T-cell response to secondary viral challenge.Conclusions: These experiments suggest that the absence of all VIP in the body, or the absence of VIP in a transplanted immune system, enhances anti-viral immunity and allo-immune responses. Modulation of the VIP pathway is a novel method to regulate post-transplant immunity. [Display omitted]