Perivascular adipose tissue remodeling impairs vasoreactivity in thermoneutral-housed rats.

Objective: Vascular pathology, characterized by impaired vasoreactivity and mitochondrial respiration, differs between the sexes. Housing rats under thermoneutral (TN) conditions causes vascular dysfunction and perturbed metabolism. We hypothesized that perivascular adipose tissue (PVAT), a vasoregulatory adipose depot with brown adipose tissue (BAT) phenotype, remodels to a white adipose (WAT) phenotype in rats housed at TN, driving diminished vasoreactivity in a sex-dependent manner. Methods: Male and female Wistar rats were housed at either room temperature (RT) or TN. Endpoints included changes in PVAT morphology, vasoreactivity in vessels with intact PVAT or transferred to PVAT of the oppositely-housed animal, vessel stiffness, vessel mitochondrial respiration and cellular signaling. Results: Remodeling of PVAT was observed in rats housed at TN; animals in this environment showed PVAT whitening and displayed diminished aortae vasodilation (p<0.05), different between the sexes. Juxtaposing PVAT from RT rats onto aortae from TN rats in females corrected vasodilation (p<0.05); this did not occur in males. In aortae of all animals housed at TN, mitochondrial respiration was significantly diminished in lipid substrate experiments (p<0.05), and there was significantly less expression of peNOS (p<0.001). Conclusions: These data are consistent with TN-induced remodeling of PVAT, notably associated with sex-specific blunting of vasoreactivity, diminished mitochondrial respiration, and altered cellular signaling.

Sex Differences in the Skeletal Muscle Response to a High Fat, High Sucrose Diet in Rats.

Men are diagnosed with type 2 diabetes at lower body mass indexes than women; the role of skeletal muscle in this sex difference is poorly understood. Type 2 diabetes impacts skeletal muscle, particularly in females who demonstrate a lower oxidative capacity compared to males. To address mechanistic differences underlying this sex disparity, we investigated skeletal muscle mitochondrial respiration in female and male rats in response to chronic high-fat, high-sugar (HFHS) diet consumption. Four-week-old Wistar Rats were fed a standard chow or HFHS diet for 14 weeks to identify sex-specific adaptations in mitochondrial respirometry and characteristics, transcriptional patterns, and protein profiles. Fat mass was greater with the HFHS diet in both sexes when controlled for body mass (p < 0.0001). Blood glucose and insulin resistance were greater in males (p = 0.01) and HFHS-fed rats (p < 0.001). HFHS-fed males had higher mitochondrial respiration compared with females (p < 0.01 sex/diet interaction). No evidence of a difference by sex or diet was found for mitochondrial synthesis, dynamics, or quality to support the mitochondrial respiration sex/diet interaction. However, transcriptomic analyses indicate sex differences in nutrient handling. Sex-specific differences occurred in PI3K/AKT signaling, PPARα/RXRα, and triacylglycerol degradation. These findings may provide insight into the clinical sex differences in body mass index threshold for diabetes development and tissue-specific progression of insulin resistance.

Single-leg exercise training augments in vivo skeletal muscle oxidative flux and vascular content and function in adults with type 2 diabetes.

KEY POINTS: People with type 2 diabetes (T2D) have impaired skeletal muscle oxidative flux due to limited oxygen delivery. In the current study, this impairment in oxidative flux in people with T2D was abrogated with a single-leg exercise training protocol. Additionally, single-leg exercise training increased skeletal muscle CD31 content, calf blood flow and state 4 mitochondrial respiration in all participants. ABSTRACT: Cardiorespiratory fitness is impaired in type 2 diabetes (T2D), conferring significant cardiovascular risk in this population; interventions are needed. Previously, we reported that a T2D-associated decrement in skeletal muscle oxidative flux is ameliorated with acute use of supplemental oxygen, suggesting that skeletal muscle oxygenation is rate-limiting to in vivo mitochondrial oxidative flux during exercise in T2D. We hypothesized that single-leg exercise training (SLET) would improve the T2D-specific impairment in in vivo mitochondrial oxidative flux during exercise. Adults with (n = 19) and without T2D (n = 22) with similar body mass indexes and levels of physical activity participated in two weeks of SLET. Following SLET, in vivo oxidative flux measured by 31 P-MRS increased in participants with T2D, but not people without T2D, measured by the increase in initial phosphocreatine synthesis (P = 0.0455 for the group × exercise interaction) and maximum rate of oxidative ATP synthesis (P = 0.0286 for the interaction). Additionally, oxidative phosphorylation increased in all participants with SLET (P = 0.0209). After SLET, there was no effect of supplemental oxygen on any of the in vivo oxidative flux measurements in either group (P > 0.02), consistent with resolution of the T2D-associated oxygen limitation previously observed at baseline in subjects with T2D. State 4 mitochondrial respiration also improved in muscle fibres ex vivo. Skeletal muscle vasculature content and calf blood flow increased in all participants with SLET (P < 0.0040); oxygen extraction in the calf increased only in T2D (P = 0.0461). SLET resolves the T2D-associated impairment of skeletal muscle in vivo mitochondrial oxidative flux potentially through improved effective blood flow/oxygen delivery.

ERK2 and Akt are negative regulators of insulin and Tumor Necrosis Factor-α stimulated VCAM-1 expression in rat aorta endothelial cells.

BACKGROUND: Diabetes is quickly becoming the most widespread disorder in the Western world. Among the most prevalent effects of diabetes is atherosclerosis, which in turn is driven in part by inflammation. Both insulin and Tumor Necrosis Factor-alpha (TNFα) increase the presence of Vascular Cellular Adhesion Molecule-1 (VCAM-1) expression. The aim of this study is to determine the effects of downregulating Extracellular signal-Regulated Kinase-2 (ERK2) and Akt on insulin and TNFa-stimulated VCAM-1 expression. METHODS: Here we begin to define the relationships between ERK2 and Akt regulation of insulin and TNFα-stimulated VCAM-1 expression in Rat Arterial Endothelial Cells (RAEC) by transfecting RAEC with ERK2 and Akt RNA interference (RNAi) and then treating these cells with insulin (10 nM) or TNFα (10 ng/mL) alone or in combination. RESULTS: Western blot analyses, flow cytometry and confocal microscopy were used to determine changes in VCAM-1 expression within the above-stated parameters. Cells transfected with ERK2 or Akt RNAi plasmids increased insulin and TNFα-stimulated VCAM-1 total protein expression significantly (P < 0.05) greater than that seen in mock transfected cells and expressed cell surface VCAM-1 greater than that seen in mock transfected cells as indicated by flow cytometry and confocal microscopy. Nevertheless, the decrease of both kinases did not increase insulin or TNFα-stimulated VCAM-1 expression above that seen when one or the other RNAi was present. CONCLUSIONS: Taken together, our results demonstrate that ERK2 and Akt may be negative regulators of insulin and TNF-α stimulated VCAM-1 and that their loss or down regulation might upregulate VCAM-1 expression and contribute to vascular disease.

Alpha-1 antitrypsin reduces severity of pseudomonas pneumonia in mice and inhibits epithelial barrier disruption and pseudomonas invasion of respiratory epithelial cells.

Nosocomial pneumonia (NP) is the third most common hospital-acquired infection and the leading cause of death due to hospital-acquired infection in the US. During pneumonia and non-pneumonia severe illness, respiratory tract secretions become enriched with the serine protease neutrophil elastase (NE). Several NE activities promote onset and severity of NP. NE in the airways causes proteolytic tissue damage, augments inflammation, may promote invasion of respiratory epithelium by bacteria, and disrupts respiratory epithelial barrier function. These NE activities culminate in enhanced bacterial replication, impaired gas exchange, fluid intrusion into the airways, and loss of bacterial containment that can result in bacteremia. Therefore, neutralizing NE activity may reduce the frequency and severity of NP. We evaluated human alpha-1 antitrypsin (AAT), the prototype endogenous NE inhibitor, as a suppressor of bacterial pneumonia and pneumonia-related pathogenesis. In AAT(+/+) transgenic mice that express human AAT in lungs, mortality due to Pseudomonas aeruginosa (P.aer) pneumonia was reduced 90% compared to non-transgenic control animals. Exogenous human AAT given to non-transgenic mice also significantly reduced P.aer pneumonia mortality. P.aer-infected AAT(+/+) mice demonstrated reduced lung tissue damage, decreased bacterial concentrations in lungs and blood, and diminished circulating cytokine concentrations compared to infected non-transgenic mice. In vitro, AAT suppressed P.aer internalization into respiratory epithelial cells and inhibited NE or P.aer-induced disruption of epithelial cell barrier function. The beneficial effects of human AAT in murine P.aer pneumonia raise the possibility of AAT use as a prophylactic treatment for NP in humans, and suggest a role for AAT as an innate immune mediator.

Patients with nontuberculous mycobacterial lung disease exhibit unique body and immune phenotypes.

RATIONALE: Among patients with nontuberculous mycobacterial lung disease is a subset of previously healthy women with a slender body morphotype, often with scoliosis and/or pectus excavatum. We hypothesize that unidentified factors predispose these individuals to pulmonary nontuberculous mycobacterial disease. OBJECTIVES: To compare body morphotype, serum adipokine levels, and whole-blood cytokine responses of patients with pulmonary nontuberculous mycobacteria (pNTM) with contemporary control subjects who are well matched demographically. METHODS: We enrolled 103 patients with pNTM and 101 uninfected control subjects of similar demographics. Body mass index and body fat were quantified. All patients with pNTM and a subset of control subjects were evaluated for scoliosis and pectus excavatum. Serum leptin and adiponectin were measured. Specific cytokines important to host-defense against mycobacteria were measured in whole blood before and after stimulation. MEASUREMENTS AND MAIN RESULTS: Patients with pNTM and control subjects were well matched for age, gender, and race. Patients with pNTM had significantly lower body mass index and body fat and were significantly taller than control subjects. Scoliosis and pectus excavatum were significantly more prevalent in patients with pNTM. The normal relationships between the adipokines and body fat were lost in the patients with pNTM, a novel finding. IFN-γ and IL-10 levels were significantly suppressed in stimulated whole blood of patients with pNTM. CONCLUSIONS: This is the first study to comprehensively compare body morphotype, adipokines, and cytokine responses between patients with NTM lung disease and demographically matched controls. Our findings suggest a novel, predisposing immunophenotype that should be mechanistically defined.

Alpha-1-antitrypsin inhibits nitric oxide production.

NO is an endogenously produced gas that regulates inflammation, vascular tone, neurotransmission, and immunity. NO production can be increased by exposing cells to several endogenous and exogenous proinflammatory mediators, including IFN-γ, TNF-α, IL-1ß, and LPS. As AAT has been shown to inhibit cell activation and suppress cytokine production associated with proinflammatory stimulation, we examined AAT for NO-suppressive function. In RAW 264.7 murine macrophagic cells, physiological AAT concentrations significantly inhibited combined LPS- and IFN-γ-induced NO synthesis, and NO synthesis inhibition was associated with decreased expression of iNOS, suppressed NF-κB activation, and reduced translocation of extracellular AAT into the interior of RAW 264.7 cells. CE-2072, a synthetic inhibitor of serine proteases, also suppressed NO production, iNOS expression, and NF-κB activation. However, AAT did not alter activation of intracellular MAPKs. In subjects with genetic AAT deficiency, exhaled NO was increased significantly compared with exhaled NO in healthy controls. These in vitro and in vivo studies suggest that AAT is an endogenous inhibitor of NO production. Administering AAT or AAT-like molecules may have use as a treatment for diseases associated with excessive NO production.

HIV infection is associated with reduced serum alpha-1-antitrypsin concentrations.

PURPOSE: Several observations suggest the presence of HIV-suppressive factors in the fluid phase of blood. Alpha-1-antitrypsin (AAT), the most abundant serine protease inhibitor in the circulation, has potent anti-HIV activity in vitro, and may function as an endogenous HIV suppressor. Therefore, we assessed serum AAT concentrations for association with HIV infection. METHODS: In this cross-sectional study, serum AAT concentrations were measured in 66 persons with HIV infection and in 45 healthy persons (Controls). In the HIV-infected group, antiretroviral therapy (ART) use was assessed and CD4+ T cell levels and plasma HIV RNA were quantified. RESULTS: Median AAT concentration was significantly lower in the HIV-infected group (1.64 mg/mL) in comparison with Controls (1.94 mg/mL; p=0.001). AAT reduction was most pronounced in the HIV-infected subgroup with CD4+ T cell levels > 200 cells/µL in comparison with Controls (p < 0.01). Serum AAT concentrations < 1.0 mg/mL are clinically significant, and concentrations below this level were identified in 4.5% of the HIV-infected group and in no Control subjects. No association between AAT levels and viral load or use of ART was observed in HIV-infected subjects. CONCLUSION: The association between reduced serum AAT concentration and HIV infection is consistent with a role for AAT as an endogenous HIV suppressor.

Exercise improvement and plasma biomarker changes with intravenous treprostinil therapy for pulmonary arterial hypertension: a placebo-controlled trial.

BACKGROUND: Pulmonary arterial hypertension (PAH) remains a poorly understood and frequently lethal disease with few treatment options. METHODS: We conducted a placebo-controlled trial of intravenous treprostinil, a prostacyclin analog, in treatment-naive PAH patients. During 12 weeks of treatment with treprostinil or placebo, we quantified 6-minute walk distance (6MW), clinical symptoms and 11 cytokines/growth factors. RESULTS: Forty-two of 44 study patients had idiopathic/familial PAH in New York Heart Association (NYHA) Class III. Treprostinil increased 6MW by a placebo-corrected median of 83 meters (p = 0.008; mean increase 93 +/- 42 meters), reduced Borg score by a median 2.0 units (p = 0.02), and improved NYHA class by a median of 1.0 (p = 0.02). There was a trend toward improved survival with treprostinil (p = 0.051). Baseline plasma angiopoietin-2 (Ang-2), vascular endothelial growth factor (VEGF), matrix metalloproteinase-9 (MMP-9) and platelet-derived growth factor (PDGF) were elevated compared with reported normal ranges. Treatment with treprostinil was associated with decreased Ang-2 levels. Improvement in 6MW distance after treatment was associated with reductions in Ang-2 and MMP-9 levels. Most of the cytokines and growth factors studied were not abnormal with disease nor did they change with treatment. CONCLUSIONS: We conclude that treprostinil treatment significantly improved exercise capacity, dyspnea and functional class. Several plasma proteins that might track disease were abnormal at baseline, and changes were associated with improved exercise capacity.

Alpha-1-antitrypsin is an endogenous inhibitor of proinflammatory cytokine production in whole blood.

Several observations suggest endogenous suppressors of inflammatory mediators are present in human blood. alpha-1-Antitrypsin (AAT) is the most abundant serine protease inhibitor in blood, and AAT possesses anti-inflammatory activity in vitro and in vivo. Here, we show that in vitro stimulation of whole blood from persons with a genetic AAT deficiency resulted in enhanced cytokine production compared with blood from healthy subjects. Using whole blood from healthy subjects, dilution of blood with RPMI tissue-culture medium, followed by incubation for 18 h, increased spontaneous production of IL-8, TNF-alpha, IL-1 beta, and IL-1R antagonist (IL-1Ra) significantly, compared with undiluted blood. Dilution-induced cytokine production suggested the presence of one or more circulating inhibitors of cytokine synthesis present in blood. Serially diluting blood with tissue-culture medium in the presence of cytokine stimulation with heat-killed Staphylococcus epidermidis (S. epi) resulted in 1.2- to 55-fold increases in cytokine production compared with S. epi stimulation alone. Diluting blood with autologous plasma did not increase the production of IL-8, TNF-alpha, IL-1 beta, or IL-1Ra, suggesting that the endogenous, inhibitory activity of blood resided in plasma. In whole blood, diluted and stimulated with S. epi, exogenous AAT inhibited IL-8, IL-6, TNF-alpha, and IL-1 beta significantly but did not suppress induction of the anti-inflammatory cytokines IL-1Ra and IL-10. These ex vivo and in vitro observations suggest that endogenous AAT in blood contributes to the suppression of proinflammatory cytokine synthesis.

Endogenous IL-32 controls cytokine and HIV-1 production.

IL-32, a proinflammatory cytokine that activates the p38MAPK and NF-kappaB pathways, induces other cytokines, for example, IL-1beta, IL-6, and TNF-alpha. This study investigated the role of endogenous IL-32 in HIV-1 infection by reducing IL-32 with small interfering (si)RNA in freshly infected PBMC and in the latently infected U1 macrophage cell line. When PBMC were pretreated with siRNA to IL-32 (siIL-32), IL-6, IFN-gamma, and TNF-alpha were reduced by 57, 51, and 36%, respectively, compared with scrambled siRNA. Cotransfection of NF-kappaB and AP-1 reporter constructs with siIL-32 decreased DNA binding of these transcription factors by 42 and 46%, respectively. Cytokine protein array analysis revealed that the inhibitory activity of siIL-32 primarily targeted Th1 and proinflammatory cytokines and chemokines, e.g., MIP-1alpha/beta. Unexpectedly, HIV-1 production (as measured by p24) increased 4-fold in these same PBMC when endogenous IL-32 was reduced. Because IFN-gamma was lower in siIL-32-treated PBMC, we blocked IFN-gamma bioactivity, which enhanced the augmentation of p24 by siIL-32. Furthermore, siIL-32 reduced the natural ligands of the HIV-1 coreceptors CCR5 (MIP-1alpha/beta and RANTES) and CXCR4 (SDF-1). Inhibition of endogenous IL-32 in U1 macrophages also increased HIV-1. When rhIL-32gamma was added to these cells, p24 levels fell by 72%; however, in the same cultures IFN-alpha increased 4-fold. Blockade of IFN-alpha/beta bioactivity in IL-32gamma-stimulated U1 cells revealed that IFN-alpha conveys the anti-HIV-1 effect of rhIL-32gamma. In summary, depletion of endogenous IL-32 reduced the levels of Th1 and proinflammatory cytokines but paradoxically increased p24, proposing IL-32 as a natural inhibitor of HIV-1.

Effect of a four-week course of interleukin-10 on cytokine production in a placebo-controlled study of HIV-1-infected subjects.

Interleukin (IL)-10 suppresses synthesis of the pro-inflammatory cytokines tumor necrosis factor (TNF)alpha, IL-1beta, and interferon (IFN)gamma. Since pro-inflammatory cytokines have been implicated in the production of human immunodeficiency virus type 1 (HIV-1), cytokine synthesis in whole blood cultures were determined during a 4-week course of subcutaneous IL-10 injections in 33 HIV-1-infected patients. Patients were randomized into four groups: placebo (nine), IL-10 at 1 microg/kg/day (nine), IL-10 at 4 microg/kg/day (six) and IL-10 at 8 microg/kg three times per week (nine). Whole blood was obtained at the beginning and conclusion of the study and was stimulated for 24 hours with the combination of IL-18 plus lipopolysaccharide. TNFalpha production in stimulated whole blood was reduced three and six hours after the first injection of IL-10 compared to subjects injected with the placebo. After four weeks of treatment, production of IFNgamma was suppressed in a greater number of patients in the IL-10 treatment groups compared to subjects in the placebo group. Similarly, IL-1beta production was lower in the IL-10 treatment groups compared to subjects receiving placebo. In contrast, after four weeks of IL-10, circulating levels of the anti-inflammatory TNF soluble receptor p55 increased dose-dependently compared to placebo subjects. Patient heterogeneity and small sample size presented difficulties in establishing statistical significance. Although the cytokine changes in our study did not demonstrate statistically significant changes, the data nevertheless reveal that four weeks of IL-10 therapy in HIV-1 infected subjects produced the anticipated suppression of pro-inflammatory cytokines.

Whole-blood interleukin-18 level during early HIV-1 infection is associated with reduced CXCR4 coreceptor expression and interferon- gamma levels.

Interleukin (IL)-18 generates T helper 1-type immunity and inhibits human immunodeficiency virus type 1 (HIV-1) in primary cells in vitro. Because IL-18 may participate in HIV-1 containment, whole-blood IL-18 levels were measured in 20 healthy control subjects and longitudinally in 28 subjects with early HIV-1 infection. Compared with those in control subjects, IL-18 levels were higher during early HIV-1 infection, and IL-18 levels predicted reduced CXCR4 HIV-1 coreceptor expression and diminished interferon (IFN)- gamma levels. By contrast, a direct association between IL-18 and IFN- gamma levels was observed in blood stimulated with lipopolysaccharide. During early HIV-1 infection, IL-18 may regulate HIV-1 coreceptor expression and have antiretroviral activity.

Frequency of beryllium-specific, TH1-type cytokine-expressing CD4+ T cells in patients with beryllium-induced disease.

BACKGROUND: Beryllium sensitization is caused by exposure to beryllium in the workplace. A subset of beryllium-sensitized (BeS) subjects progress to chronic beryllium disease (CBD), a disorder characterized by a CD4+ T-cell alveolitis and granulomatous inflammation. Whether biomarkers are present in blood that would allow separation of CBD from beryllium sensitization without invasive pulmonary procedures is unknown. OBJECTIVE: The aim of this study was to determine whether the quantity of beryllium-specific T cells in blood of patients with CBD differs from that found in BeS subjects. METHODS: Beryllium-induced T-cell proliferation and T H 1-type cytokine secretion were determined in blood cells from 33 patients with CBD and 18 BeS subjects. RESULTS: We demonstrate here that patients with CBD have a significantly elevated number of IFN-gamma-producing and IL-2-producing beryllium-specific CD4+ T cells in blood compared with both BeS and normal control subjects. In contrast, no difference in beryllium-induced proliferation of blood T cells was seen between BeS patients and patients with CBD. Compared with the blood beryllium lymphocyte proliferation test, which detected beryllium-induced proliferation in 65% of BeS patients and patients with CBD, ELISPOT analysis detected IFN-gamma secretion in 80% of these subjects. Higher numbers of beryllium-specific cells in blood were also associated with the extent of alveolar inflammation, as measured by both bronchoalveolar lavage white blood cell and lymphocyte counts. CONCLUSION: The frequency of beryllium-specific T cells in the blood of beryllium-exposed subjects may be a useful biomarker that helps discriminate between beryllium sensitization and progression to CBD.

Immunity to human immunodeficiency virus (HIV) in children with chronic HIV infection receiving highly active antiretroviral therapy.

Our objective was to describe the CD4-mediated human immunodeficiency virus (HIV)-specific cell-mediated immunity (CMI) and its virologic and immunologic correlates in children with chronic HIV infection on highly active antiretroviral therapy (HAART). Twelve HIV-infected children on stable antiretroviral therapy with a median level of CD4+ lymphocytes (CD4%) of 25.5% and a median viral load (VL) of 786 HIV RNA copies/ml were enrolled in this study. Nine of these children were also cytomegalovirus (CMV) seropositive. Blood mononuclear cells, stimulated with HIV and CMV antigens, were used to measure lymphocyte proliferation and to enumerate gamma interferon (IFN-gamma)-producing CD4+ cells. HIV CMI and CMV CMI were detected in similar proportions of patients and correlated with each other, although the HIV responses were less robust. HIV lymphocyte proliferation significantly increased with lower HIV VL and showed a trend to increase with higher CD4% and longer time on HAART. The in vitro IFN-gamma response to HIV or CMV was not affected by CD4%, VL, or HAART. Pediatric patients with established HIV infection on HAART frequently exhibit HIV CMI despite undetectable HIV replication. We concluded that the association between HIV CMI and CMV CMI indicates that the same factors govern responsiveness to either antigen.