Endothelial cell PTP1B regulates leukocyte recruitment during allergic inflammation

Targeting VCAM-1: a therapeutic opportunity for vascular damage

INTRODUCTION

The vascular cell adhesion molecule (VCAM-1) is a transmembrane sialoglycoprotein detected in activated endothelial and vascular smooth muscle cells involved in the adhesion and transmigration of inflammatory cells into damaged tissue. Widely used as a pro-inflammatory marker, its potential role as a targeting molecule has not been thoroughly explored.

AREAS COVERED

We discuss the current evidence supporting the potential targeting of VCAM-1 in atherosclerosis, diabetes, hypertension and ischemia/reperfusion injury.

EXPERT OPINION

There is emerging evidence that VCAM-1 is more than a biomarker and may be a promising therapeutic target for vascular diseases. While there are neutralizing antibodies that allow preclinical research, the development of pharmacological tools to activate or inhibit this protein are required to thoroughly assess its therapeutic potential.

PTPN1 Deficiency Modulates BMPR2 Signaling and Induces Endothelial Dysfunction in Pulmonary Arterial Hypertension

Bone morphogenic protein receptor 2 (BMPR2) expression and signaling are impaired in pulmonary arterial hypertension (PAH). How BMPR2 signaling is decreased in PAH is poorly understood. Protein tyrosine phosphatases (PTPs) play important roles in vascular remodeling in PAH. To identify whether PTPs modify BMPR2 signaling, we used a siRNA-mediated high-throughput screening of 22,124 murine genes in mouse myoblastoma reporter cells using ID1 expression as readout for BMPR2 signaling. We further experimentally validated the top hit, PTPN1 (PTP1B), in healthy human pulmonary arterial endothelial cells (PAECs) either silenced by siRNA or exposed to hypoxia and confirmed its relevance to PAH by measuring PTPN1 levels in blood and PAECs collected from PAH patients. We identified PTPN1 as a novel regulator of BMPR2 signaling in PAECs, which is downregulated in the blood of PAH patients, and documented that downregulation of PTPN1 is linked to endothelial dysfunction in PAECs. These findings point to a potential involvement for PTPN1 in PAH and will aid in our understanding of the molecular mechanisms involved in the disease.

LPP polymorphisms are risk factors for allergic rhinitis in the Chinese Han population

BACKGROUND

Lipoma preferred partner (LPP) polymorphisms are related to immune diseases, but the role of LPP gene in the pathogenesis of allergic rhinitis (AR) is unclear. The current study aimed to explore the contribution of LPP variants to AR susceptibility in the Chinese Han population.

METHODS

A total of 992 healthy controls and 992 patients with AR were recruited. Agena MassARRAY system was applied for genotyping. Odds ratios (OR) and 95% confidence intervals (CI) adjusted by age, sex, and body mass index (BMI) were calculated to conduct the risk assessment of LPP variants in people with a predisposition to AR. Additionally, multifactor dimensionality reduction (MDR) was applied to identify high-order interaction models for AR risk.

RESULTS

We found that rs2030519-G (p = 0.027, OR: 1.15, 95% CI: 1.02-1.31), rs6780858-G (p = 0.019, OR: 1.16, 95% CI: 1.03-1.32), and rs60946162-T (p = 0.014, OR: 1.18, 95% CI: 1.03-1.34) were associated with increased susceptibility to AR. Subgroup analyses indicated the interaction of LPP polymorphisms in terms of age, gender, and BMI with AR susceptibility (p < 0.05, OR > 1). MDR analysis revealed that rs60946162 had the information gain (0.40%) of individual attribute regarding AR.

CONCLUSION

Our results first determined that rs2030519, rs6780858, and rs60946162 were correlated with increased susceptibility to AR in the Chinese Han population, which add to our understanding of the impact of LPP gene variants on AR development.

Isolation and characterization of extracellular vesicle subpopulations from tissues

Extracellular vesicles (EVs) are lipid bilayered membrane structures released by all cells. Most EV studies have been performed by using cell lines or body fluids, but the number of studies on tissue-derived EVs is still limited. Here, we present a protocol to isolate up to six different EV subpopulations directly from tissues. The approach includes enzymatic treatment of dissociated tissues followed by differential ultracentrifugation and density separation. The isolated EV subpopulations are characterized by electron microscopy and RNA profiling. In addition, their protein cargo can be determined with mass spectrometry, western blot and ExoView. Tissue-EV isolation can be performed in 22 h, but a simplified version can be completed in 8 h. Most experiments with the protocol have used human melanoma metastases, but the protocol can be applied to other cancer and non-cancer tissues. The procedure can be adopted by researchers experienced with cell culture and EV isolation.

β-Glucosylceramide From Allergic Mothers Enhances Offspring Responsiveness to Allergen

In animals and humans, offspring of allergic mothers have increased responsiveness to allergen and the allergen-specificity of the offspring can be different than that of the mother. In our preclinical models, the mother's allergic responses influence development of the fetus and offspring by elevating numbers of cells in dendritic cell subsets. A major question is the identity of maternal factors of allergic mothers that alter offspring development of responsiveness to allergen. Lipids are altered during allergic responses and lipids are transported to the fetus for growth and formation of fetal membranes. We hypothesized that pro-inflammatory lipids, that are elevated in allergic mothers, are transported to the fetus and regulate fetal immune development. We demonstrate in this report that there was a significant 2-fold increase in β-glucosylceramides (βGlcCer) in allergic mothers, the fetal liver and her offspring. The βGlcCer were transported from mother's plasma, across the placenta, to the fetus and in breastmilk to the offspring. Administration of βGlcCer to non-allergic mothers was sufficient for offspring responses to allergen. Importantly, maternal administration of a clinically relevant pharmacological inhibitor of βGlcCer synthase returned βGlcCer to normal levels in the allergic mothers and her offspring and blocked the offspring increase in dendritic cell subsets and offspring allergen responsiveness. In summary, allergic mothers had increased βGlcCer that was transported to offspring and mediated increases in offspring DCs and responsiveness to allergen. These data have a significant impact on our understanding of mechanisms for development of allergies in offspring of allergic mothers and have the potential to lead to novel interventions that significantly impact risk for allergic disease early in life.

Anti-Inflammatory and Protein Tyrosine Phosphatase 1B Inhibitory Metabolites from the Antarctic Marine-Derived Fungal Strain Penicillium glabrum SF-7123

A chemical investigation of the marine-derived fungal strain Penicillium glabrum (SF-7123) revealed a new citromycetin (polyketide) derivative (1) and four known secondary fungal metabolites, i.e, neuchromenin (2), asterric acid (3), myxotrichin C (4), and deoxyfunicone (5). The structures of these metabolites were identified primarily by extensive analysis of their spectroscopic data, including NMR and MS data. Results from the initial screening of anti-inflammatory effects showed that 2, 4, and 5 possessed inhibitory activity against the excessive production of nitric oxide (NO) in lipopolysaccharide (LPS)-stimulated BV2 microglial cells, with IC₅₀ values of 2.7 µM, 28.1 µM, and 10.6 µM, respectively. Compounds 2, 4, and 5 also inhibited the excessive production of NO, with IC₅₀ values of 4.7 µM, 41.5 µM, and 40.1 µM, respectively, in LPS-stimulated RAW264.7 macrophage cells. In addition, these compounds inhibited LPS-induced overproduction of prostaglandin E₂ in both cellular models. Further investigation of the most active compound (2) revealed that these anti-inflammatory effects were associated with a suppressive effect on the over-expression of inducible nitric oxide synthase and cyclooxygenase-2. Finally, we showed that the anti-inflammatory effects of compound 2 were mediated via the downregulation of inflammation-related pathways such as those dependent on nuclear factor kappa B and p38 mitogen-activated protein kinase in LPS-stimulated BV2 and RAW264.7 cells. In the evaluation of the inhibitory effects of the isolated compounds on protein tyrosine phosphate 1B (PTP1B) activity, compound 4 was identified as a noncompetitive inhibitor of PTP1B, with an IC₅₀ value of 19.2 µM, and compound 5 was shown to inhibit the activity of PTP1B, with an IC₅₀ value of 24.3 µM, by binding to the active site of the enzyme. Taken together, this study demonstrates the potential value of marine-derived fungal isolates as a bioresource for bioactive compounds.

Marine Alkaloids with Anti-Inflammatory Activity: Current Knowledge and Future Perspectives

Alkaloids are nitrogenous compounds with various biological activities. Alkaloids with anti-inflammatory activity are commonly found in terrestrial plants, but there are few records of the identification and characterization of the activity of these compounds in marine organisms such as fungi, bacteria, sponges, ascidians, and cnidarians. Seaweed are a source of several already elucidated bioactive compounds, but few studies have described and characterized the activity of seaweed alkaloids with anti-inflammatory properties. In this review, we have gathered the current knowledge about marine alkaloids with anti-inflammatory activity and suggest future perspectives for the study and bioprospecting of these compounds.

Angiotensin II induces apoptosis of cardiac microvascular endothelial cells via regulating PTP1B/PI3K/Akt pathway

Endothelial cell apoptosis and renin-angiotensin-aldosterone system (RAAS) activation are the major pathological mechanisms for cardiovascular disease and heart failure; however, the interaction and mechanism between them remain unclear. Investigating the role of PTP1B in angiotensin II (Ang II)-induced apoptosis of primary cardiac microvascular endothelial cells (CMECs) may provide direct evidence of the link between endothelial cell apoptosis and RAAS. Isolated rat CMECs were treated with different concentrations of Ang II to induce apoptosis, and an Ang II concentration of 4 nM was selected as the effective dose for the subsequent studies. The CMECs were cultured for 48 h with or without Ang II (4 nM) in the absence or presence of the PTP1B inhibitor TCS 401 (8 μM) and the PI3K inhibitor LY294002 (10 μM). The level of CMEC apoptosis was assessed by TUNEL staining and caspase-3 activity. The protein expressions of PTP1B, PI3K, Akt, p-Akt, Bcl-2, Bax, caspase-3, and cleaved caspase-3 were determined by Western blot (WB). The results showed that Ang II increased apoptosis of CMECs, upregulated PTP1B expression, and inhibited the PI3K/Akt pathway. Furthermore, cotreatment with PTP1B inhibitor significantly decreased the number of apoptotic CMECs induced by Ang II, along with increased PI3K expression, phosphorylation of Akt and the ratio of Bcl-2/Bax, decreased caspase-3 activity, and a cleaved caspase-3/caspase-3 ratio, while treatment with LY294002 partly inhibited the anti-apoptotic effect of the PTP1B inhibitor. Ang II induces apoptosis of primary rat CMECs via regulating the PTP1B/PI3K/Akt pathway.

Sex Differences in IL-33-Induced STAT6-Dependent Type 2 Airway Inflammation

Sex differences in asthma prevalence are well-documented but poorly understood. Murine models have contributed to our understanding of mechanisms that could regulate this sex disparity, though the majority of these studies have examined responses present after Th2 adaptive immunity is established. We have now investigated how sex influences acute activation of innate cell populations in the lung upon initial exposure to the model antigen, ovalbumin (OVA), in the presence of IL-33 (OVA+IL-33), to prime the lungs for type 2 immunity. We also examined how inflammatory responses induced by OVA+IL-33 were altered in mice lacking the STAT6 transcription factor, which is activated by IL-13, an effector cytokine of IL-33. Our data demonstrate that type 2 inflammation induced by OVA+IL-33 was more severe in female mice compared to males. Females exhibited greater cytokine and chemokine production, eosinophil influx and activation, macrophage polarization to the alternatively activated phenotype, and expansion of group 2 innate lymphoid cells (ILC2s). While increases in ILC2s and eosinophils were largely independent of STAT6 in both males and females, many other responses were STAT6-dependent only in female mice. Our findings indicate that a subset of type 2 inflammatory responses induced by OVA+IL-33 require STAT6 in both males and females and that enhanced type 2 inflammation in females, compared to males, is associated with greater IL-13 protein production. Our findings suggest blunted IL-13 production in males may protect against type 2 inflammation initiated by OVA+IL-33 delivery to the lung.

VCAM-1 induces signals that stimulate ZO-1 serine phosphorylation and reduces ZO-1 localization at lung endothelial cell junctions

Endothelial cell VCAM-1 regulates recruitment of lymphocytes, eosinophils, mast cells, or dendritic cells during allergic inflammation. In this report, we demonstrated that, during allergic lung responses, there was reduced zonula occludens (ZO)-1 localization in lung endothelial cell junctions, whereas there was increased lung endothelial cell expression of VCAM-1, N-cadherin, and angiomotin. In vitro, leukocyte binding to VCAM-1 reduced ZO-1 in endothelial cell junctions. Using primary human endothelial cells and mouse endothelial cell lines, Ab crosslinking of VCAM-1 increased serine phosphorylation of ZO-1 and induced dissociation of ZO-1 from endothelial cell junctions, demonstrating that VCAM-1 regulates ZO-1. Moreover, VCAM-1 induction of ZO-1 phosphorylation and loss of ZO-1 localization at cell junctions was blocked by inhibition of VCAM-1 intracellular signals that regulate leukocyte transendothelial migration, including NOX2, PKCα, and PTP1B. Furthermore, exogenous addition of the VCAM-1 signaling intermediate H₂ O₂ (1 μM) stimulated PKCα-dependent and PTP1B-dependent serine phosphorylation of ZO-1 and loss of ZO-1 from junctions. Overexpression of ZO-1 blocked leukocyte transendothelial migration. In summary, leukocyte binding to VCAM-1 induces signals that stimulated ZO-1 serine phosphorylation and reduced ZO-1 localization at endothelial cell junctions during leukocyte transendothelial migration.

Mechanism for initiation of food allergy: Dependence on skin barrier mutations and environmental allergen costimulation

BACKGROUND

Mechanisms for the development of food allergy in neonates are unknown but clearly linked in patient populations to a genetic predisposition to skin barrier defects. Whether skin barrier defects contribute functionally to development of food allergy is unknown.

OBJECTIVE

The purpose of the study was to determine whether skin barrier mutations, which are primarily heterozygous in patient populations, contribute to the development of food allergy.

METHODS

Mice heterozygous for the filaggrin (Flg)ft and Tmem79ma mutations were skin sensitized with environmental and food allergens. After sensitization, mice received oral challenge with food allergen, and then inflammation, inflammatory mediators, and anaphylaxis were measured.

RESULTS

We define development of inflammation, inflammatory mediators, and food allergen-induced anaphylaxis in neonatal mice with skin barrier mutations after brief concurrent cutaneous exposure to food and environmental allergens. Moreover, neonates of allergic mothers have increased responses to suboptimal sensitization with food allergens. Importantly, responses to food allergens by these neonatal mice were dependent on genetic defects in skin barrier function and on exposure to environmental allergens. ST2 blockade during skin sensitization inhibited the development of anaphylaxis, antigen-specific IgE, and inflammatory mediators. Neonatal anaphylactic responses and antigen-specific IgE were also inhibited by oral pre-exposure to food allergen, but interestingly, this was blunted by concurrent pre-exposure of the skin to environmental allergen.

CONCLUSION

These studies uncover mechanisms for food allergy sensitization and anaphylaxis in neonatal mice that are consistent with features of human early-life exposures and genetics in patients with clinical food allergy and demonstrate that changes in barrier function drive development of anaphylaxis to food allergen.

Leukocyte Breaching of Endothelial Barriers: The Actin Link

Leukocyte transendothelial migration (TEM) takes place across micron-wide gaps in specific post-capillary venules generated by the transmigrating leukocyte. Because endothelial cells contain a dense cytoskeletal network, transmigrating leukocytes must overcome these mechanical barriers as they squeeze their nuclei through endothelial gaps and pores. Recent findings suggest that endothelial cells are not a passive barrier, and upon engagement by transmigrating leukocytes trigger extensive dynamic modifications of their actin cytoskeleton. Unexpectedly, endothelial contractility functions as a restrictor of endothelial gap enlargement rather than as a facilitator of gap formation as was previously suggested. In this review we discuss current knowledge regarding how accurately timed endothelial actin-remodeling events are triggered by squeezing leukocytes and coordinate leukocyte TEM while preserving blood vessel integrity.

Protein tyrosine phosphatase 1B negatively regulates S100A9-mediated lung damage during respiratory syncytial virus exacerbations

Protein tyrosine phosphatase 1B (PTP1B) has anti-inflammatory potential but PTP1B responses are desensitized in the lung by prolonged cigarette smoke exposure. Here we investigate whether PTP1B expression affects lung disease severity during respiratory syncytial viral (RSV) exacerbations of chronic obstructive pulmonary disease (COPD). Ptp1b(-/-) mice infected with RSV exhibit exaggerated immune cell infiltration, damaged epithelial cell barriers, cytokine production, and increased apoptosis. Elevated expression of S100A9, a damage-associated molecular pattern molecule, was observed in the lungs of Ptp1b(-/-) mice during RSV infection. Utilizing a neutralizing anti-S100A9 IgG antibody, it was determined that extracellular S100A9 signaling significantly affects lung damage during RSV infection. Preexposure to cigarette smoke desensitized PTP1B activity that coincided with enhanced S100A9 secretion and inflammation in wild-type animals during RSV infection. S100A9 levels in human bronchoalveolar lavage fluid had an inverse relationship with lung function in healthy subjects, smokers, and COPD subjects. Fully differentiated human bronchial epithelial cells isolated from COPD donors cultured at the air liquid interface secreted more S100A9 than cells from healthy donors or smokers following RSV infection. Together, these findings show that reduced PTP1B responses contribute to disease symptoms in part by enhancing S100A9 expression during viral-associated COPD exacerbations.

Protein tyrosine phosphatase 1B (PTP1B) is dispensable for IgE-mediated cutaneous reaction in vivo

Mast cells play a critical role in allergic reactions. The cross-linking of FcεRI-bound IgE with multivalent antigen initiates a cascade of signaling events leading to mast cell activation. It has been well-recognized that cross linking of FcεRI mediates tyrosine phosphorylation. However, the mechanism involved in tyrosine dephosphorylation in mast cells is less clear. Here we demonstrated that protein tyrosine phosphatase 1B (PTP1B)-deficient mast cells showed increased IgE-mediated phosphorylation of the signal transducer and activator of transcription 5 (STAT5) and enhanced production of CCL9 (MIP-1γ) and IL-6 in IgE-mediated mast cells activation in vitro. However, IgE-mediated calcium mobilization, β-hexaosaminidase release (degranulation), and phosphorylation of IκB and MAP kinases were not affected by PTP1B deficiency. Furthermore, PTP1B deficient mice showed normal IgE-dependent passive cutaneous anaphylaxis and late phase cutaneous reactions in vivo. Thus, PTP1B specifically regulates IgE-mediated STAT5 pathway, but is redundant in influencing mast cell function in vivo.

Recent insights into endothelial control of leukocyte extravasation

In the process of leukocyte migration from the circulation across the vascular wall, the crosstalk with endothelial cells that line the blood vessels is essential. It is now firmly established that in endothelial cells important signaling events are initiated upon leukocyte adhesion that impinge on the regulation of cell-cell contact and control the efficiency of transendothelial migration. In addition, several external factors such as shear force and vascular stiffness were recently identified as important regulators of endothelial signaling and, consequently, leukocyte transmigration. Here, I review recent insights into endothelial signaling events that are linked to leukocyte migration across the vessel wall. In this field, protein phosphorylation and Rho-mediated cytoskeletal dynamics are still widely studied using increasingly sophisticated mouse models. In addition, activation of tyrosine phosphatases, changes in endothelial cell stiffness as well as different vascular beds have all been established as important factors in endothelial signaling and leukocyte transmigration. Finally, I address less-well-studied but interesting components in the endothelium that also control transendothelial migration, such as the ephrins and their Eph receptors, that provide novel insights in the complexity associated with this process.

γ-Tocopherol supplementation of allergic female mice augments development of CD11c+CD11b+ dendritic cells in utero and allergic inflammation in neonates

γ-Tocopherol increases responses to allergen challenge in allergic adult mice, but it is not known whether γ-tocopherol regulates the development of allergic disease. Development of allergic disease often occurs early in life. In clinical studies and animal models, offspring of allergic mothers have increased responsiveness to allergen challenge. Therefore, we determined whether γ-tocopherol augments development of allergic responses in offspring of allergic female mice. Allergic female mice were supplemented with γ-tocopherol starting at mating. The pups from allergic mothers developed allergic lung responses, whereas pups from saline-treated mothers did not respond to allergen challenge. The γ-tocopherol supplementation of allergic female mice increased the numbers of eosinophils twofold in the pup bronchoalveolar lavage and lungs after allergen challenge. There was also about a twofold increase in pup lung CD11b(+) subsets of CD11c(+) dendritic cells and in numbers of these dendritic cells expressing the transcription factor IRF4. There was no change in several CD11b(-) dendritic cell subsets. Furthermore, maternal supplementation with γ-tocopherol increased the number of fetal liver CD11b(+)CD11c(+) dendritic cells twofold in utero. In the pups, γ-tocopherol increased lung expression of the inflammatory mediators CCL11, amphiregulin, activin A, and IL-5. In conclusion, maternal supplementation with γ-tocopherol increased fetal development of subsets of dendritic cells that are critical for allergic responses and increased development of allergic responses in pups from allergic mothers. These results have implications for supplementation of allergic mothers with γ-tocopherol in prenatal vitamins.

Regulation of allergic lung inflammation by endothelial cell transglutaminase 2

Tissue transglutaminase 2 (TG2) is an enzyme with multiple functions, including catalysis of serotonin conjugation to proteins (serotonylation). Previous research indicates that TG2 expression is upregulated in human asthma and in the lung endothelium of ovalbumin (OVA)-challenged mice. It is not known whether endothelial cell TG2 is required for allergic inflammation. Therefore, to determine whether endothelial cell TG2 regulates allergic inflammation, mice with an endothelial cell-specific deletion of TG2 were generated, and these mice were sensitized and challenged in the airways with OVA. Deletion of TG2 in endothelial cells blocked OVA-induced serotonylation in lung endothelial cells, but not lung epithelial cells. Interestingly, deletion of endothelial TG2 reduced allergen-induced increases in respiratory system resistance, number of eosinophils in the bronchoalveolar lavage, and number of eosinophils in the lung tissue. Endothelial cell deletion of TG2 did not alter expression of adhesion molecules, cytokines, or chemokines that regulate leukocyte recruitment, consistent with other studies, demonstrating that deletion of endothelial cell signals does not alter lung cytokines and chemokines during allergic inflammation. Taken together, the data indicate that endothelial cell TG2 is required for allergic inflammation by regulating the recruitment of eosinophils into OVA-challenged lungs. In summary, TG2 functions as a critical signal for allergic lung responses. These data identify potential novel targets for intervention in allergy/asthma.

Deletion of Protein Tyrosine Phosphatase 1B (PTP1B) Enhances Endothelial Cyclooxygenase 2 Expression and Protects Mice from Type 1 Diabetes-Induced Endothelial Dysfunction

Protein tyrosine phosphatase 1B (PTP1B) dephosphorylates receptors tyrosine kinase and acts as a molecular brake on insulin signaling pathway. Conditions of metabolic dysfunction increase PTP1B, when deletion of PTP1B protects against metabolic disorders by increasing insulin signaling. Although vascular insulin signaling contributes to the control of glucose disposal, little is known regarding the direct role of PTP1B in the control of endothelial function. We hypothesized that metabolic dysfunctions increase PTP1B expression in endothelial cells and that PTP1B deletion prevents endothelial dysfunction in situation of diminished insulin secretion. Type I diabetes (T1DM) was induced in wild-type (WT) and PTP1B-deficient mice (KO) with streptozotocin (STZ) injection. After 28 days of T1DM, KO mice exhibited a similar reduction in body weight and plasma insulin levels and a comparable increase in glycemia (WT: 384±20 vs. Ko: 432±29 mg/dL), cholesterol and triglycerides, as WT mice. T1DM increased PTP1B expression and impaired endothelial NO-dependent relaxation, in mouse aorta. PTP1B deletion did not affect baseline endothelial function, but preserved endothelium-dependent relaxation, in T1DM mice. NO synthase inhibition with L-NAME abolished endothelial relaxation in control and T1DM WT mice, whereas L-NAME and the cyclooxygenases inhibitor indomethacin were required to abolish endothelium relaxation in T1DM KO mice. PTP1B deletion increased COX-2 expression and PGI₂ levels, in mouse aorta and plasma respectively, in T1DM mice. In parallel, simulation of diabetic conditions increased PTP1B expression and knockdown of PTP1B increased COX-2 but not COX-1 expression, in primary human aortic endothelial cells. Taken together these data indicate that deletion of PTP1B protected endothelial function by compensating the reduction in NO bioavailability by increasing COX-2-mediated release of the vasodilator prostanoid PGI₂, in T1DM mice.

α-Tocopherol supplementation of allergic female mice inhibits development of CD11c+CD11b+ dendritic cells in utero and allergic inflammation in neonates

α-Tocopherol blocks responses to allergen challenge in allergic adult mice, but it is not known whether α-tocopherol regulates the development of allergic disease. Development of allergic disease often occurs early in life. In clinical studies and animal models, offspring of allergic mothers have increased responsiveness to allergen challenge. Therefore, we determined whether α-tocopherol blocked development of allergic responses in offspring of allergic female mice. Allergic female mice were supplemented with α-tocopherol starting at mating. The pups from allergic mothers developed allergic lung responses, whereas pups from saline-treated mothers did not respond to the allergen challenge, and α-tocopherol supplementation of allergic female mice resulted in a dose-dependent reduction in eosinophils in the pup bronchoalveolar lavage and lungs after allergen challenge. There was also a reduction in pup lung CD11b(+) dendritic cell subsets that are critical to development of allergic responses, but there was no change in several CD11b(-) dendritic cell subsets. Furthermore, maternal supplementation with α-tocopherol reduced the number of fetal liver CD11b(+) dendritic cells in utero. In the pups, there was reduced allergen-induced lung mRNA expression of IL-4, IL-33, TSLP, CCL11, and CCL24. Cross-fostering pups at the time of birth demonstrated that α-tocopherol had a regulatory function in utero. In conclusion, maternal supplementation with α-tocopherol reduced fetal development of subsets of dendritic cells that are critical for allergic responses and reduced development of allergic responses in pups from allergic mothers. These results have implications for supplementation of allergic mothers with α-tocopherol.

Gene deletion of protein tyrosine phosphatase 1B protects against sepsis-induced cardiovascular dysfunction and mortality

OBJECTIVE

Cardiovascular dysfunction is a major cause of mortality in patients with sepsis. Recently, we showed that gene deletion or pharmacological inhibition of protein tyrosine phosphatase 1B (PTP1B) improves endothelial dysfunction and reduces the severity of experimental heart failure. However, the cardiovascular effect of PTP1B invalidation in sepsis is unknown. Thus, we explored the beneficial therapeutic effect of PTP1B gene deletion on lipopolysaccharide (LPS)-induced cardiovascular dysfunction, inflammation, and mortality.

APPROACH AND RESULTS

PTP1B(-/-) or wild-type mice received LPS (15 mg/kg) or vehicle followed by subcutaneous fluid resuscitation (saline, 30 mL/kg). α-1-dependent constriction and endothelium-dependent dilatation, assessed on isolated perfused mesenteric arteries, were impaired 8 hours after LPS and significantly improved in PTP1B(-/-) mice. This was associated with reduced vascular expression of interleukin1-β, intercellular adhesion molecule-1, vascular cell adhesion molecule-1, cyclooxygenase-2, and inducible nitric oxide synthase mRNA. PTP1B gene deletion also limited LPS-induced cardiac dysfunction assessed by echocardiography, left ventricular pressure-volume curves, and in isolated perfused hearts. PTP1B(-/-) mice also displayed reduced LPS-induced cardiac expression of tumor necrosis factor-α, interleukin1-β, intercellular adhesion molecule-1, vascular cell adhesion molecule-1, and Gp91phox, as well as of several markers of cellular infiltration. PTP1B deficiency also reduced cardiac P38 and extracellular signal-regulated protein kinase 1 and 2 phosphorylation and increased phospholamban phosphorylation. Finally, PTP1B(-/-) mice displayed a markedly reduced LPS-induced mortality, an effect also observed using a pharmacological PTP1B inhibitor. PTP1B deletion also improved survival in a cecal ligation puncture model of sepsis.

CONCLUSIONS

PTP1B gene deletion protects against septic shock-induced cardiovascular dysfunction and mortality, and this may be the result of the profound reduction of cardiovascular inflammation. PTP1B is an attractive target for the treatment of sepsis.

Protein tyrosine phosphatase 1B deficiency ameliorates murine experimental colitis via the expansion of myeloid-derived suppressor cells

Protein tyrosine phosphatase 1B (PTP1B) is a key molecule in modulating low-degree inflammatory conditions such as diabetes. The role of PTP1B in other chronic inflammations, however, remains unknown. Here, we report that PTP1B deficiency ameliorates Dextran Sulfate Sodium (DSS)-induced murine experimental colitis via expanding CD11b⁺Gr-1⁺ myeloid-derived suppressor cells (MDSCs). Employing DSS-induced murine experimental colitis as inflammatory animal model, we found that, compared with wild-type littermates, PTP1B-null mice demonstrated greater resistance to DSS-induced colitis, as reflected by slower weight-loss, greater survival rates and decreased PMN and macrophage infiltration into the colon. The evidence collectively also demonstrated that the resistance of PTP1B-null mice to DSS-induced colitis is based on the expansion of MDSCs. First, PTP1B-null mice exhibited a greater frequency of MDSCs in the bone marrow (BM), peripheral blood and spleen when compared with wild-type littermates. Second, PTP1B levels in BM leukocytes were significantly decreased after cells were induced into MDSCs by IL-6 and GM-CSF, and the MDSC induction occurred more rapidly in PTP1B-null mice than in wild-type littermates, suggesting PTP1B as a negative regulator of MDSCs. Third, the adoptive transfer of MDSCs into mice with DSS-colitis significantly attenuated colitis, which accompanies with a decreased serum IL-17 level. Finally, PTP1B deficiency increased the frequency of MDSCs from BM cells likely through enhancing the activities of signal transducer and activator of transcription 3 (STAT3) and Janus kinase 2 (JAK2). In conclusion, our study provides the first evidences that PTP1B deficiency ameliorates murine experimental colitis via expanding MDSCs.

Isoforms of Vitamin E Differentially Regulate PKC α and Inflammation: A Review

Vitamin E regulation of disease has been extensively studied but most studies focus on the α-tocopherol isoform of vitamin E. These reports indicate contradictory outcomes for anti-inflammatory functions of the α-tocopherol isoform of vitamin E with regards to animal and clinical studies. These seemingly disparate results are consistent with our recent studies demonstrating that purified natural forms of vitamin E have opposing regulatory functions during inflammation. In this review, we discuss that α-tocopherol inhibits whereas γ-tocopherol elevates allergic inflammation, airway hyperresponsiveness, leukocyte transendothelial migration, and endothelial cell adhesion molecule signaling through protein kinase Cα. Moreover, we have demonstrated that α-tocopherol is an antagonist and γ-tocopherol is an agonist of PKCα through direct binding to a regulatory domain of PKCα. In summary, we have determined mechanisms for opposing regulatory functions of α-tocopherol and γ-tocopherol on inflammation. Information from our studies will have significant impact on the design of clinical studies and on vitamin E consumption.