Diet-induced obesity in mice impairs host defense against Klebsiella pneumonia in vivo and glucose transport and bactericidal functions in neutrophils in vitro.

Obesity impairs host defense against Klebsiella pneumoniae, but responsible mechanisms are incompletely understood. To determine the impact of diet-induced obesity on pulmonary host defense against K. pneumoniae, we fed 6-wk-old male C57BL/6j mice a normal diet (ND) or high-fat diet (HFD) (13% vs. 60% fat, respectively) for 16 wk. Mice were intratracheally infected with Klebsiella, assayed at 24 or 48 h for bacterial colony-forming units, lung cytokines, and leukocytes from alveolar spaces, lung parenchyma, and gonadal adipose tissue were assessed using flow cytometry. Neutrophils from uninfected mice were cultured with and without 2-deoxy-d-glucose (2-DG) and assessed for phagocytosis, killing, reactive oxygen intermediates (ROI), transport of 2-DG, and glucose transporter (GLUT1-4) transcripts, and protein expression of GLUT1 and GLUT3. HFD mice had higher lung and splenic bacterial burdens. In HFD mice, baseline lung homogenate concentrations of IL-1ß, IL-6, IL-17, IFN-γ, CXCL2, and TNF-α were reduced relative to ND mice, but following infection were greater for IL-6, CCL2, CXCL2, and IL-1ß (24 h only). Despite equivalent lung homogenate leukocytes, HFD mice had fewer intraalveolar neutrophils. HFD neutrophils exhibited decreased Klebsiella phagocytosis and killing and reduced ROI to heat-killed Klebsiella in vitro. 2-DG transport was lower in HFD neutrophils, with reduced GLUT1 and GLUT3 transcripts and protein (GLUT3 only). Blocking glycolysis with 2-DG impaired bacterial killing and ROI production in neutrophils from mice fed ND but not HFD. Diet-induced obesity impairs pulmonary Klebsiella clearance and augments blood dissemination by reducing neutrophil killing and ROI due to impaired glucose transport.

Adipokines and Subclinical Cardiovascular Disease in Post-Menopausal Women: Study of Women's Health Across the Nation.

Background The menopausal transition is characterized by increased cardiovascular risk, weight gain, and increased adiposity for many women. The adipose-derived secretory proteins adiponectin and leptin are associated with insulin resistance, metabolic syndrome, and cardiovascular disease but their role in subclinical atherosclerotic disease is unclear. This cross-sectional study evaluated the associations of adiponectin and leptin with carotid artery intima-media thickness, adventitial diameter, presence of carotid plaques, and brachial-ankle pulse wave velocity (baPWV) in women aged 54 to 65 years. Methods and Results Participants were 1399 women from SWAN (Study of Women's Health Across the Nation), a community-based study of women transitioning through menopause. Carotid ultrasound and baPWV measures were obtained at SWAN follow-up visits 12 or 13, when 97% of participants were post-menopausal. Adipokines were assayed from serum specimens obtained concurrently at these visits. Linear and logistic regression models were used to evaluate adiponectin or leptin, both log-transformed attributable to skewness, in relationship to carotid artery intima-media thickness, adventitial diameter, baPWV, and presence of carotid plaque. Covariates included age, race, study site, smoking, alcohol use, obesity, cardiovascular disease risk factors, and menopausal status. Lower levels of adiponectin were related to greater carotid artery intima-media thickness, wider adventitial diameter, and faster baPWV; associations were attenuated after adjusting for cardiovascular disease risk factors. Higher levels of leptin were associated with greater carotid artery intima-media thickness and wider adventitial diameter in minimally and fully adjusted models, and contrary to expectation, with slower baPWV, particularly among women with diabetes mellitus or obesity. Conclusions Adiponectin and leptin are 2 important inflammatory pathways that may contribute to adverse subclinical cardiovascular disease risk profiles in women at midlife.

PGE2 accounts for bidirectional changes in alveolar macrophage self-renewal with aging and smoking.

Alveolar macrophages (AMs) are resident immune cells of the lung that are critical for host defense. AMs are capable of proliferative renewal, yet their numbers are known to decrease with aging and increase with cigarette smoking. The mechanism by which AM proliferation is physiologically restrained, and whether dysregulation of this brake contributes to altered AM numbers in pathologic circumstances, however, remains unknown. Mice of advanced age exhibited diminished basal AM numbers and contained elevated PGE2 levels in their bronchoalveolar lavage fluid (BALF) as compared with young mice. Exogenous PGE2 inhibited AM proliferation in an E prostanoid receptor 2 (EP2)-cyclic AMP-dependent manner. Furthermore, EP2 knockout (EP2 KO) mice exhibited elevated basal AM numbers, and their AMs resisted the ability of PGE2 and aged BALF to inhibit proliferation. In contrast, increased numbers of AMs in mice exposed to cigarette smoking were associated with reduced PGE2 levels in BALF and were further exaggerated in EP2 KO mice. Collectively, our findings demonstrate that PGE2 functions as a tunable brake on AM numbers under physiologic and pathophysiological conditions.

Oxidative Inactivation of the Proteasome Augments Alveolar Macrophage Secretion of Vesicular SOCS3.

Extracellular vesicles (EVs) contain a diverse array of molecular cargoes that alter cellular phenotype and function following internalization by recipient cells. In the lung, alveolar macrophages (AMs) secrete EVs containing suppressor of cytokine signaling 3 (SOCS3), a cytosolic protein that promotes homeostasis via vesicular transfer to neighboring alveolar epithelial cells. Although changes in the secretion of EV molecules-including but not limited to SOCS3-have been described in response to microenvironmental stimuli, the cellular and molecular machinery that control alterations in vesicular cargo packaging remain poorly understood. Furthermore, the use of quantitative methods to assess the sorting of cytosolic cargo molecules into EVs is lacking. Here, we utilized cigarette smoke extract (CSE) exposure of AMs as an in vitro model of oxidative stress to address these gaps in knowledge. We demonstrate that the accumulation of reactive oxygen species (ROS) in AMs was sufficient to augment vesicular SOCS3 release in this model. Using nanoparticle tracking analysis (NTA) in tandem with a new carboxyfluorescein succinimidyl ester (CFSE)-based intracellular protein packaging assay, we show that the stimulatory effects of CSE were at least in part attributable to elevated amounts of SOCS3 packaged per EV secreted by AMs. Furthermore, the use of a 20S proteasome activity assay alongside treatment of AMs with conventional proteasome inhibitors strongly suggest that ROS stimulated SOCS3 release via inactivation of the proteasome. These data demonstrate that tuning of AM proteasome function by microenvironmental oxidants is a critical determinant of the packaging and secretion of cytosolic SOCS3 protein within EVs.

Dietary Omega Polyunsaturated Fatty Acid Intake and Patient-Reported Outcomes in Systemic Lupus Erythematosus: The Michigan Lupus Epidemiology and Surveillance Program.

OBJECTIVE: To examine associations between dietary intake of omega-3 (n-3; generally antiinflammatory) and omega-6 (n-6; generally proinflammatory) fatty acids and patient-reported outcomes in systemic lupus erythematosus (SLE). METHODS: This study was based on the population-based Michigan Lupus Epidemiology and Surveillance cohort. Estimates of n-3 and n-6 intake were derived from Diet History Questionnaire II items (past year with portion size version). Patient-reported outcomes included self-reported lupus activity (Systemic Lupus Activity Questionnaire [SLAQ]). Multivariable regression, adjusted for age, sex, race, and body mass index, was used to assess associations between absolute intake of n-3 and n-6, as well as the n-6:n-3 ratio, and patient-reported outcomes. RESULTS: Among 456 SLE cases, 425 (93.2%) were female, 207 (45.4%) were African American, and the mean ± SD age was 52.9 ± 12.3 years. Controlling for potential confounders, the average SLAQ score was significantly higher by 0.3 points (95% confidence interval [95% CI] 0.1, 0.6; P = 0.013) with each unit increase of the n-6:n-3 ratio. Both lupus activity and Patient-Reported Outcomes Measurement Information System (PROMIS) sleep disturbance scores were lower with each 1-gram/1,000 kcal increase of n-3 fatty acids (SLAQ regression coefficient ß = -0.8 [95% CI -1.6, 0.0]; P = 0.055; PROMIS sleep ß = -1.1 [95% CI -2.0, -0.2]; P = 0.017). Higher n-3 intakes were nonsignificantly associated with lower levels of depressive symptoms and comorbid fibromyalgia, and with higher quality of life, whereas results for the n6:n3 ratio trended in the opposite direction. CONCLUSION: This population-based study suggests that higher dietary intake of n-3 fatty acids and lower n-6:n-3 ratios are favorably associated with patient-reported outcomes in SLE, particularly self-reported lupus activity and sleep quality.

Ablation of the leptin receptor in myeloid cells impairs pulmonary clearance of Streptococcus pneumoniae and alveolar macrophage bactericidal function.

Leptin is a pleiotropic hormone produced by white adipose tissue that regulates appetite and many physiological functions, including the immune response to infection. Genetic leptin deficiency in humans and mice impairs host defenses against respiratory tract infections. Since leptin deficiency is associated with obesity and other metabolic abnormalities, we generated mice that lack the leptin receptor (LepRb) in cells of the myeloid linage (LysM-LepRb-KO) to evaluate its impact in lean metabolically normal mice in a murine model of pneumococcal pneumonia. We observed higher lung and spleen bacterial burdens in LysM-LepRb-KO mice following an intratracheal challenge with Streptococcus pneumoniae. Although numbers of leukocytes recovered from bronchoalveolar lavage fluid did not differ between groups, we did observe higher levels of pulmonary IL-13 and TNFα in LysM-LepRb-KO mice 48 h post infection. Phagocytosis and killing of ingested S. pneumoniae were also impaired in alveolar macrophages (AMs) from LysM-LepRb-KO mice in vitro and were associated with reduced LTB4 and enhanced PGE2 synthesis in vitro. Pretreatment of AMs with LTB4 and the cyclooxygenase inhibitor, indomethacin, restored phagocytosis but not bacterial killing in vitro. These results confirm our previous observations in leptin-deficient ( ob/ob) and fasted mice and demonstrate that decreased leptin action, as opposed to metabolic irregularities associated with obesity or starvation, is responsible for the defective host defense against pneumococcal pneumonia. They also provide novel targets for therapeutic intervention in humans with bacterial pneumonia.

Alveolar Epithelial Cell-Derived Prostaglandin E2 Serves as a Request Signal for Macrophage Secretion of Suppressor of Cytokine Signaling 3 during Innate Inflammation.

Preservation of gas exchange mandates that the pulmonary alveolar surface restrain unnecessarily harmful inflammatory responses to the many challenges to which it is exposed. These responses reflect the cross-talk between alveolar epithelial cells (AECs) and resident alveolar macrophages (AMs). We recently determined that AMs can secrete suppressor of cytokine signaling (SOCS) proteins within microparticles. Uptake of these SOCS-containing vesicles by epithelial cells inhibits cytokine-induced STAT activation. However, the ability of epithelial cells to direct AM release of SOCS-containing vesicles in response to inflammatory insults has not been studied. In this study, we report that SOCS3 protein was elevated in bronchoalveolar lavage fluid of both virus- and bacteria-infected mice, as well as in an in vivo LPS model of acute inflammation. In vitro studies revealed that AEC-conditioned medium (AEC-CM) enhanced AM SOCS3 secretion above basal levels. Increased amounts of PGE2 were present in AEC-CM after LPS challenge, and both pharmacologic inhibition of PGE2 synthesis in AECs and neutralization of PGE2 in AEC-CM implicated this prostanoid as the major AEC-derived factor mediating enhanced AM SOCS3 secretion. Moreover, pharmacologic blockade of PGE2 synthesis or genetic deletion of a PGE2 synthase similarly attenuated the increase in bronchoalveolar lavage fluid SOCS3 noted in lungs of mice challenged with LPS in vivo. These results demonstrate a novel tunable form of cross-talk in which AECs use PGE2 as a signal to request SOCS3 from AMs to dampen their endogenous inflammatory responses during infection.

Higher Leptin and Adiponectin Concentrations Predict Poorer Performance-based Physical Functioning in Midlife Women: the Michigan Study of Women's Health Across the Nation.

BACKGROUND: Excess fat mass is a greater contributor to functional limitations than is reduced lean mass or the presence of obesity-related conditions. The impact of fat mass on physical functioning may be due to adipokines, adipose-derived proteins that have pro- or anti-inflammatory properties. METHODS: Serum samples from 1996 to 2003 that were assayed for leptin, adiponectin, and resistin were provided by 511 participants from the Michigan site of the Study of Women's Health Across the Nation. Physical functioning performance was assessed annually during study visits from 1996 to 2003. RESULTS: Among this population of Black and White women (mean baseline age = 45.6 years, SD = 2.7 years), all of whom were premenopausal at baseline, higher baseline leptin concentrations predicted longer stair climb, sit-to-rise, and 2-pound lift times and shorter forward reach distance (all p < .01). This relationship persisted after adjustment for age, BMI, percent skeletal muscle mass, race/ethnicity, economic strain, bodily pain, diabetes, knee osteoarthritis, and C-reactive protein. Baseline total adiponectin concentrations did not predict any mobility measures but did predict quadriceps strength; a 1 µg/mL higher adiponectin concentration was associated with 0.64 Nm lower quadriceps strength (p = .02). Resistin was not associated with any of the physical functioning performance measures. Change in the adipokines was not associated with physical functioning. CONCLUSION: In this population of middle-aged women, higher baseline leptin concentrations predicted poorer mobility-based functioning, whereas higher adiponectin concentrations predicted reduced quadriceps strength. These findings suggest that the relationship between the adipokines and physical functioning performance is independent of other known correlates of poor functioning.

Glucocorticoid-Augmented Efferocytosis Inhibits Pulmonary Pneumococcal Clearance in Mice by Reducing Alveolar Macrophage Bactericidal Function.

Inhaled corticosteroids (ICS) increase community-acquired pneumonia (CAP) incidence in patients with chronic obstructive pulmonary disease (COPD) by unknown mechanisms. Apoptosis is increased in the lungs of COPD patients. Uptake of apoptotic cells (ACs) ("efferocytosis") by alveolar macrophages (AMøs) reduces their ability to combat microbes, including Streptococcus pneumoniae, the most common cause of CAP in COPD patients. Having shown that ICS significantly increase AMø efferocytosis, we hypothesized that this process, termed glucocorticoid-augmented efferocytosis, might explain the association of CAP with ICS therapy in COPD. To test this hypothesis, we studied the effects of fluticasone, AC, or both on AMøs of C57BL/6 mice in vitro and in an established model of pneumococcal pneumonia. Fluticasone plus AC significantly reduced TLR4-stimulated AMø IL-12 production, relative to either treatment alone, and decreased TNF-α, CCL3, CCL5, and keratinocyte-derived chemoattractant/CXCL1, relative to AC. Mice treated with fluticasone plus AC before infection with viable pneumococci developed significantly more lung CFUs at 48 h. However, none of the pretreatments altered inflammatory cell recruitment to the lungs at 48 h postinfection, and fluticasone plus AC less markedly reduced in vitro mediator production to heat-killed pneumococci. Fluticasone plus AC significantly reduced in vitro AMø killing of pneumococci, relative to other conditions, in part by delaying phagolysosome acidification without affecting production of reactive oxygen or nitrogen species. These results support glucocorticoid-augmented efferocytosis as a potential explanation for the epidemiological association of ICS therapy of COPD patients with increased risk for CAP, and establish murine experimental models to dissect underlying molecular mechanisms.

Transcellular delivery of vesicular SOCS proteins from macrophages to epithelial cells blunts inflammatory signaling.

JAK-STAT signaling mediates the actions of numerous cytokines and growth factors, and its endogenous brake is the family of SOCS proteins. Consistent with their intracellular roles, SOCS proteins have never been identified in the extracellular space. Here we report that alveolar macrophages can secrete SOCS1 and -3 in exosomes and microparticles, respectively, for uptake by alveolar epithelial cells and subsequent inhibition of STAT activation. Secretion is tunable and occurs both in vitro and in vivo. SOCS secretion into lung lining fluid was diminished by cigarette smoking in humans and mice. Secretion and transcellular delivery of vesicular SOCS proteins thus represent a new model for the control of inflammatory signaling, which is subject to dysregulation during states of inflammation.

Adipokines and Cysteinyl Leukotrienes in the Pathogenesis of Asthma.

Background. The prevalence of obesity has increased dramatically over the last decades, and its association with asthma is being increasingly recognized. Aims. Our hypothesis is that increased leptin and decreased adiponectin levels in obese subjects play a direct role in regulating inflammation in asthmatics. We wanted to examine the hypothesis that cysteinyl leukotrienes (cys-LT), inflammatory mediators that are regulated by adipokines, are involved in the pathogenesis of asthma. Methods. We studied a population of asthmatics and nonasthmatics, who in turn were divided into obese and nonobese categories. We examined leptin and its ratio to adiponectin, in asthmatics and nonasthmatics, with and without obesity. In addition, we measured cys-LT levels in exhaled breath condensate (EBC) and in peripheral blood monocytes (PBM) in these groups. Results. Leptin levels were increased in obese asthmatics compared to obese nonasthmatics. The leptin/adiponectin (L/A) ratio was higher in obese asthmatics compared to obese nonasthmatics. EBC cys-LT levels were elevated in asthmatics compared to nonasthmatics. Discussion. Proinflammatory adipokines, released from adipose tissue, may promote an asthma phenotype through enhanced cys-LT production that may result in more prevalent and difficult to control airway disease.

Combined exposure to cigarette smoke and nontypeable Haemophilus influenzae drives development of a COPD phenotype in mice.

BACKGROUND: Cigarette smoke (CS) is the major etiologic factor of chronic obstructive pulmonary disease (COPD). CS-exposed mice develop emphysema and mild pulmonary inflammation but no airway obstruction, which is also a prominent feature of COPD. Therefore, CS may interact with other factors, particularly respiratory infections, in the pathogenesis of airway remodeling in COPD. METHODS: C57BL/6 mice were exposed to CS for 2 h a day, 5 days a week for 8 weeks. Mice were also exposed to heat-killed non-typeable H. influenzae (HK-NTHi) on days 7 and 21. One day after the last exposure to CS, mice were sacrificed and lung inflammation and mechanics, emphysematous changes, and goblet cell metaplasia were assessed. Mice exposed to CS or HK-NTHi alone or room air served as controls. To determine the susceptibility to viral infections, we also challenged these mice with rhinovirus (RV). RESULTS: Unlike mice exposed to CS or HK-NTHi alone, animals exposed to CS/HK-NTHi developed emphysema, lung inflammation and goblet cell metaplasia in both large and small airways. CS/HK-NTHi-exposed mice also expressed increased levels of mucin genes and cytokines compared to mice in other groups. CS/HK-NTHi-exposed mice infected with RV demonstrated increased viral persistence, sustained neutrophilia, and further increments in mucin gene and chemokine expression compared to other groups. CONCLUSIONS: These findings indicate that in addition to CS, bacteria may also contribute to development of COPD, particularly changes in airways. Mice exposed to CS/HK-NTHi are also more susceptible to subsequent viral infection than mice exposed to either CS or HK-NTHi alone.

Role of CC chemokine receptor 4 in natural killer cell activation during acute cigarette smoke exposure.

Cigarette smoke (CS)-induced lung injury involves innate immune responses. The activation of innate effector cells is thought to require cross talk with dendritic cells (DCs) and macrophages, but the mediators of interaction are unknown. One candidate, CC chemokine receptor 4 (CCR4), is expressed by innate and adaptive effector cells, and its ligands are produced by DCs and macrophages. Using flow cytometry and confocal microscopy, we defined innate responses of lung myeloid DCs, macrophages, and conventional natural killer (NK) cells in mice exposed to CS over 4 days and examined the contribution of CCR4 using CCR4 knockout (CCR4(-/-)) mice. CS affected populations differently, causing an increase in F4/80(+) macrophages, a reduction in parenchymal CD11c(+)CD11b(+)CD103(-) DCs, but no effect on mucosal CD11c(+)CD11b(-)CD103(+) DCs. CS also induced a population of primed/activated CD69(+) NK cells and bronchoepithelial expression of the stress-related NKG2D receptor-activating protein, retinoic acid early transcript 1. CS-exposed CCR4(-/-) mice were similar to controls regarding effects on DCs and macrophages but displayed substantially impaired NK priming/activation and reduced expression of transcripts for interferon gamma, CXCL10, and retinoic acid early transcript 1. Quantitative confocal microscopy revealed that lungs of CS-exposed CCR4(-/-) mice had significantly reduced contacts of NK cells with CD11c(+) cells. These findings demonstrate that acute CS exposure elicits NK cell responses and suggest that CCR4 promotes NK cell priming/activation by mediating contacts with sentinel cells in the lung.

Bisphenol A at concentrations relevant to human exposure enhances histamine and cysteinyl leukotriene release from bone marrow-derived mast cells.

Bisphenol A (BPA), a monomer of polycarbonate plastics and epoxide resin, acts as an endocrine-active compound and has been shown to enhance the inflammatory response to allergen challenge. Previous reports in rodents have demonstrated that perinatal BPA exposure alters airway inflammation following sensitization and challenge to ovalbumin in juvenile and adult offspring. Additionally, a high concentration of BPA has been shown to enhance mediator release in mast cell lines. This study aimed to determine if short-term BPA exposure, at levels relevant to human exposure, enhances mast cell release of histamine and cysteinyl leukotrienes (CysLTs). Primary murine bone marrow-derived mast cells (BMMC) produced from the femurs of female C57BL/6 mice were stimulated with BPA or estradiol (E2) in vitro. It was observed that both BPA and E2 increased BMMC histamine release over a range of nanomolar concentrations (1-1000 nM). The estrogen receptor (ER) antagonist ICI 182,780 partially blocked the ability of E2, but not BPA, to elevate histamine release. BPA also increased CysLT release, which was not abrogated by ER inhibition. It was also observed that the ability of BPA to enhance histamine and CysLT release was inhibited by blocking the extracellular signal-regulated kinase (ERK) pathway with U0126 or by chelating extracellular calcium (Ca(2+)) using EGTA. In summary, these experiments are the first to demonstrate that acute BPA exposure enhances mast cell histamine and CysLT release in vitro--an effect that is not dependent on an ER-mediated mechanism. Instead, BPA-induced mast cell histamine and CysLT release may be mediated, in part, by the ERK pathway and extracellular Ca(2+) concentrations. These data suggest that exposure to BPA at levels relevant to human exposure may provoke an acute inflammatory response in atopic individuals via enhanced mast cell activation.

Perinatal bisphenol A exposures increase production of pro-inflammatory mediators in bone marrow-derived mast cells of adult mice.

Bisphenol A (BPA) is a widely used monomer of polycarbonate plastics and epoxide resin that has been implicated in asthma pathogenesis when exposure occurs to the developing fetus. However, few studies have examined the relationship between perinatal BPA exposure and asthma pathogenesis in adulthood. This study used an isogenic mouse model to examine the influence of perinatal BPA exposure via maternal diet on inflammatory mediators associated with asthma in 6-month-old adult offspring by measuring bone marrow-derived mast cell (BMMC) production of lipid mediators (cysteinyl leukotrienes and prostaglandin D2), cytokines (interleukin [IL]-4, IL-5, IL-6, IL-13, and tumor necrosis factor [TNF]-α), and histamine. Global DNA methylation levels in BMMCs from adult offspring were determined to elucidate a potential regulatory mechanism linking perinatal exposure to mast cell phenotype later in life. Four BPA exposure doses were tested: low (50 ng BPA/kg diet, n = 5), medium (50 µg BPA/kg diet, n = 4), high (50 mg BPA/kg diet, n = 4), and control (n = 3). Following BMMC activation, increases in cysteinyl leukotriene (p < 0.01) and TNFα (p < 0.05) production were observed in all BPA-exposure groups, and increases in prostaglandin D2 (p < 0.01) and IL-13 (p < 0.01) production were observed in the high exposure group. Additionally, BMMCs from adult mice in all exposure groups displayed a decrease in global DNA methylation compared to control animals. Thus, perinatal BPA exposure displayed a long-term influence on mast cell-mediated production of pro-inflammatory mediators associated with asthma and global DNA methylation levels, suggesting a potential for mast cell dysregulation, which could affect pulmonary inflammation associated with allergic airway disease into adulthood.

The relationship between longitudinal serum leptin measures and measures of magnetic resonance imaging-assessed knee joint damage in a population of mid-life women.

BACKGROUND AND OBJECTIVE: Serum leptin measures are associated with radiographic knee osteoarthritis, but no studies have examined leptin levels with respect to different measures of knee joint damage from MRI. METHODS: Participants in the Michigan Study of Women's Health Across the Nation underwent bilateral knee MRIs at follow-up visit 11 for assessment of cartilage defects, bone marrow lesions, osteophytes, meniscal tears, synovitis and joint effusion. Serum leptin measures were available from baseline, follow-up visits 1 and 3-7. RESULTS: Baseline serum leptin levels were associated with greater odds of having more severe knee joint damage at follow-up visit 11 after adjustment for age, smoking status, menopause status and body mass index residuals. The greatest effect was observed for osteophytes; a 5 ng/ml increase in baseline leptin was associated with 24% higher odds of having larger osteophytes (95% CI 1.17 to 1.32). Correlations with baseline serum leptin were greatest for MRI-assessed osteophytes (r=0.41), followed by effusion (r=0.32), synovitis (r=0.30), cartilage defects (r=0.28), bone marrow lesions (r=0.24) and meniscal abnormalities (r=0.21). CONCLUSIONS: Leptin levels 10 years prior to MRI assessment were associated with the presence of cartilage defects, bone marrow lesions, osteophytes, meniscal tears, synovitis and effusion among a population of middle-aged women. Understanding the role that leptin plays in the joint degradation process is critical for development of more targeted interventions for osteoarthritis.

Prostaglandin E2 induction during mouse adenovirus type 1 respiratory infection regulates inflammatory mediator generation but does not affect viral pathogenesis.

Respiratory viruses cause substantial disease and are a significant healthcare burden. Virus-induced inflammation can be detrimental to the host, causing symptoms during acute infection and leading to damage that contributes to long-term residual lung disease. Prostaglandin E2 (PGE2) is a lipid mediator that is increased in response to many viral infections, and inhibition of PGE2 production during respiratory viral infection often leads to a decreased inflammatory response. We tested the hypothesis that PGE2 promotes inflammatory responses to mouse adenovirus type 1 (MAV-1) respiratory infection. Acute MAV-1 infection increased COX-2 expression and PGE2 production in wild type mice. Deficiency of the E prostanoid 2 receptor had no apparent effect on MAV-1 pathogenesis. Virus-induced induction of PGE2, IFN-γ, CXCL1, and CCL5 was reduced in mice deficient in microsomal PGE synthase-1 (mPGES-1(-/-) mice). However, there were no differences between mPGES-1(+/+) and mPGES-1(-/-) mice in viral replication, recruitment of leukocytes to airways or lung inflammation. Infection of both mPGES­1(+/+) and mPGES-1(-/-) mice led to protection against reinfection. Thus, while PGE2 promotes the expression of a variety of cytokines in response to acute MAV-1 infection, PGE2 synthesis does not appear to be essential for generating pulmonary immunity.

Associations of testosterone and sex hormone binding globulin with adipose tissue hormones in midlife women.

OBJECTIVE: Regulators of adipose tissue hormones remain incompletely understood, but may include sex hormones. As adipose tissue hormones have been shown to contribute to numerous metabolic and cardiovascular disorders, understanding their regulation in midlife women is of clinical importance. Therefore, we assessed the associations between testosterone (T) and sex hormone binding globulin (SHBG) with leptin, high molecular weight (HMW) adiponectin, and the soluble form of the leptin receptor (sOB-R) in healthy midlife women. DESIGN AND METHODS: Cross-sectional analyses were performed using data from 1,881 midlife women (average age 52.6 (±2.7) years) attending the sixth Annual follow-up visit of the multiethnic Study of Women's Health Across the Nation. RESULTS: T was weakly negatively associated with both HMW adiponectin and sOB-R (r = -0.12 and r = -0.10, respectively; P < 0.001 for both), and positively associated with leptin (r = 0.17; P < 0.001). SHBG was more strongly and positively associated with both HMW adiponectin and sOB-R (r = 0.29 and r = 0.24, respectively; P < 0.001 for both), and more strongly and negatively associated with leptin (r = -0.27; P < 0.001). Adjustment for fat mass, insulin resistance, or waist circumference only partially diminished associations with HMW adiponectin and sOB-R, but attenuated associations with leptin. In conclusion, in these midlife women, lower SHBG values, and to a lesser extent, higher T levels, were associated with lower, or less favorable, levels of adiponectin and sOB-R, independent of fat mass. CONCLUSIONS: These data suggest that variation in these adipose hormones resulting from lower SHBG levels, and possibly, though less likely, greater androgenicity, may contribute to susceptibility for metabolic and cardiovascular outcomes during midlife in women.

Aberrantly activated EGFR contributes to enhanced IL-8 expression in COPD airways epithelial cells via regulation of nuclear FoxO3A.

BACKGROUND: Decreased activity of forkhead transcription factor class O (FoxO)3A, a negative regulator of NF-κB-mediated chemokine expression, is implicated in the pathogenesis of chronic obstructive pulmonary disease (COPD). Previously, we showed that quercetin reduces lung inflammation in a murine model of COPD. Here, we examined the mechanisms underlying decreased FoxO3A activation and its modulation by quercetin in COPD human airway epithelial cells and in a COPD mouse model. METHODS: Primary COPD and normal human airway epithelial cells were treated with quercetin, LY294002 or erlotinib for 2 weeks. IL-8 was measured by ELISA. FoxO3A, Akt, and epidermal growth factor (EGF) receptor (EGFR) phosphorylation and nuclear FoxO3A levels were determined by Western blot analysis. Effects of quercetin on lung chemokine expression, nuclear FoxO3A levels and phosphorylation of EGFR and Akt were determined in COPD mouse model. RESULTS: Compared with normal, COPD cells showed significantly increased IL-8, which negatively correlated with nuclear FoxO3A levels. COPD bronchial biopsies also showed reduced nuclear FoxO3A. Decreased FoxO3A in COPD cells was associated with increased phosphorylation of EGFR, Akt and FoxO3A and treatment with quercetin, LY294002 or erlotinib increased nuclear FoxO3A and decreased IL-8 and phosphorylation of Akt, EGFR and FoxO3A, Compared with control, elastase/LPS-exposed mice showed decreased nuclear FoxO3A, increased chemokines and phosphorylation of EGFR and Akt. Treatment with quercetin partially reversed these changes. CONCLUSIONS: In COPD airways, aberrant EGFR activity increases PI 3-kinase/Akt-mediated phosphorylation of FoxO3A, thereby decreasing nuclear FoxO3A and increasing chemokine expression. Quercetin restores nuclear FoxO3A and reduces chemokine expression partly by modulating EGFR/PI 3-kinase/Akt activity.

Ablation of leptin receptor-mediated ERK activation impairs host defense against Gram-negative pneumonia.

The adipocyte-derived hormone leptin plays an important role in regulation of energy homeostasis and the innate immune response against bacterial infections. Leptin's actions are mediated by signaling events initiated by phosphorylation of tyrosine residues on the long form of the leptin receptor. We recently reported that disruption of leptin receptor-mediated STAT3 activation augmented host defense against pneumococcal pneumonia. In this report, we assessed leptin receptor-mediated ERK activation, a pathway that was ablated in the l/l mouse through a mutation of the tyrosine 985 residue in the leptin receptor, to determine its role in host defense against bacterial pneumonia in vivo and in alveolar macrophage (AM) antibacterial functions in vitro. l/l mice exhibited increased mortality and impaired pulmonary bacterial clearance after intratracheal challenge with Klebsiella pneumoniae. The synthesis of cysteinyl-leukotrienes was reduced and that of PGE(2) enhanced in AMs in vitro and the lungs of l/l mice after infection with K. pneumoniae in vivo. We also observed reduced phagocytosis and killing of K. pneumoniae in AMs from l/l mice that was associated with reduced reactive oxygen intermediate production in vitro. cAMP, known to suppress phagocytosis, bactericidal capacity, and reactive oxygen intermediate production, was also increased 2-fold in AMs from l/l mice. Pharmacologic blockade of PGE(2) synthesis reduced cAMP levels and overcame the defective phagocytosis and killing of bacteria in AMs from l/l mice in vitro. These results demonstrate that leptin receptor-mediated ERK activation plays an essential role in host defense against bacterial pneumonia and in leukocyte antibacterial effector functions.