Obesity-induced adipokine imbalance impairs mouse pulmonary vascular endothelial function and primes the lung for injury. Sci Rep. 2015;5:11362. [PMID: 26068229 PMCID: PMC4464323 DOI: 10.1038/srep11362]

Adipose Gene Expression Profile Changes With Lung Allograft Reperfusion

Obesity is a risk factor for primary graft dysfunction (PGD), a form of lung injury resulting from ischemia-reperfusion after lung transplantation, but the impact of ischemia-reperfusion on adipose tissue is unknown. We evaluated differential gene expression in thoracic visceral adipose tissue (VAT) before and after lung reperfusion. Total RNA was isolated from thoracic VAT sampled from six subjects enrolled in the Lung Transplant Body Composition study before and after allograft reperfusion and quantified using the Human Gene 2.0 ST array. Kyoto Encyclopedia of Genes and Genomes pathway analysis revealed enrichment for genes involved in complement and coagulation cascades and Jak-STAT signaling pathways. Overall, 72 genes were upregulated and 56 genes were downregulated in the postreperfusion time compared with baseline. Long pentraxin-3, a gene and plasma protein previously associated with PGD, was the most upregulated gene (19.5-fold increase, p = 0.04). Fibronectin leucine-rich transmembrane protein-3, a gene associated with cell adhesion and receptor signaling, was the most downregulated gene (4.3-fold decrease, p = 0.04). Ischemia-reperfusion has a demonstrable impact on gene expression in visceral adipose tissue in our pilot study of nonobese, non-PGD lung transplant recipients. Future evaluation will focus on differential adipose tissue gene expression and the development of PGD after transplant.

Diet-induced obese mice exhibit altered immune responses to acute lung injury induced by Escherichia coli

OBJECTIVE

Obesity has been associated with impaired immunity and increased susceptibility to bacterial infection. It also exerts protective effects against mortality secondary to acute lung injury. The effects of obesity on immune responses to acute lung injury induced by Escherichia coli were investigated to determine if the above-mentioned differences in its effects were related to infection severity.

METHODS

Diet-induced obesity (DIO) and lean control mice received intranasal instillations of 10(9) or 10(10) CFUs of E. coli. The immune responses were examined at 0 h (uninfected), 24 h, and 96 h postinfection.

RESULTS

Following infection, the DIO mice exhibited higher leukocyte, interleukin (IL)-10, IL-6, and tumor necrosis factor-α levels and more severe lung injury than the lean mice. Following inoculation with 10(10) CFUs of E. coli, the DIO mice exhibited higher mortality and more severe inflammation-induced injury than the lean mice, but no differences in E. coli counts were noted between the two groups. However, inoculated with 10(9) CFUs of E. coli, the DIO mice exhibited smaller E. coli burdens at 24 h and 96 h after infection, as well as lower concentrations of IL-10 and tumor necrosis factor-α and less severe lung injury at 96 h after infection.

CONCLUSIONS

The results support the emerging view that obesity may be beneficial in the setting of milder infection but detrimental in the setting of more severe infection.

"Obesity Paradox" in Acute Respiratory Distress Syndrome: Asystematic Review and Meta-Analysis

Background

It is unclear whether an “obesity paradox” exists in the respiratory system, especially in acute respiratory distress syndrome (ARDS) and acute lung injury (ALI). Previous studies have postulated a causal relation between obesity and ARDS/ALI but have lacked power to form a definitive conclusion.

Objective

To investigate the relationships between obesity, ARDS/ALIrisk, and mortality.

Methods

A systematic search current to April 2016 was performed in Pubmed, EMBASE, Medline, Cochrane databases to find relevant studies. All studies that estimate the effect of obesity in the morbidity and mortality of ARDS/ALI were included.

Results

A total of 24 studies including 9,187,248 subjects were analyzed. The combined results from 16 studies that examined the effect of obesity in morbidity of ARDS/ALI showed an89% increase in odds ratio(pooled odds ratios (OR) 1.89, 95% confidence intervals (CI) 1.45 to 2.47). In subgroup analysis, compared to normal weight, obesity was associated with an increased risk of ARDS/ALI (OR1.57, 95% CI 1.30–1.90 for obese (BMI30-39.9kg/m²); OR1.75, 95% CI 1.42–2.15 for obese(BMI≥30kg/m²); OR1.67, 95% CI 1.04–2.68 for morbid obese(BMI≥40kg/m²)). The combined results from 9 studies that examined the effect of obesity in mortality of ARDS/ALI had a pooled odds ratio(pooled OR 0.63, 95% CI 0.41 to 0.98). Inversely, obesity was significantly associated with reduced risk of ARDS/ALI mortality(OR0.88, 95% CI 0.78–1.00 for overweight(BMI≤18.5m²); OR0.74, 95% CI 0.64–0.84 for obese (BMI30-39.9kg/m²);OR0.84, 95% CI 0.75–0.94 for 60days mortality; OR0.38, 95% CI 0.22–0.66 for 90days mortality).

Conclusions

Our data identify obesity as an important risk factor for the development of ARDS/ALI; however, ARDS/ALI outcomes are improved in this population when compared to individuals with a normal body mass index. This meta-analysis results supported ‘‘obesity paradox” in ARDS/ALI.

Omentin protects against LPS-induced ARDS through suppressing pulmonary inflammation and promoting endothelial barrier via an Akt/eNOS-dependent mechanism

Acute respiratory distress syndrome (ARDS) is characterized by increased pulmonary inflammation and endothelial barrier permeability. Omentin has been shown to benefit obesity-related systemic vascular diseases; however, its effects on ARDS are unknown. In the present study, the level of circulating omentin in patients with ARDS was assessed to appraise its clinical significance in ARDS. Mice were subjected to systemic administration of adenoviral vector expressing omentin (Ad-omentin) and one-shot treatment of recombinant human omentin (rh-omentin) to examine omentin's effects on lipopolysaccharide (LPS)-induced ARDS. Pulmonary endothelial cells (ECs) were treated with rh-omentin to further investigate its underlying mechanism. We found that a decreased level of circulating omentin negatively correlated with white blood cells and procalcitonin in patients with ARDS. Ad-omentin protected against LPS-induced ARDS by alleviating the pulmonary inflammatory response and endothelial barrier injury in mice, accompanied by Akt/eNOS pathway activation. Treatment of pulmonary ECs with rh-omentin attenuated inflammatory response and restored adherens junctions (AJs), and cytoskeleton organization promoted endothelial barrier after LPS insult. Moreover, the omentin-mediated enhancement of EC survival and differentiation was blocked by the Akt/eNOS pathway inactivation. Therapeutic rh-omentin treatment also effectively protected against LPS-induced ARDS via the Akt/eNOS pathway. Collectively, these data indicated that omentin protects against LPS-induced ARDS by suppressing inflammation and promoting the pulmonary endothelial barrier, at least partially, through an Akt/eNOS-dependent mechanism. Therapeutic strategies aiming to restore omentin levels may be valuable for the prevention or treatment of ARDS.

Autophagy and Obesity-Related Lung Disease

Obesity-related disease is a significant source of premature death and economic burden globally. It is also a common comorbidity in patients suffering from lung disease, affecting both severity and treatment success. However, this complex association between obesity and the lung is poorly understood. Autophagy is a self-recycling homeostatic process that has been linked to beneficial or deleterious effects, depending on the specific lung disease. Obesity affects autophagy in a tissue-specific manner, activating autophagy in adipocytes and impairing autophagy in hepatocytes, immune cells, and pancreatic β-cells, among others. Obesity is also characterized by chronic low-grade inflammation that can be modulated by the pro- and antiinflammatory effects of the autophagic machinery. Scant evidence exists regarding the impact of autophagy in obesity-related lung diseases, but there are communal pathways that could be related to disease pathogenesis. Important signaling molecules in obesity, including IL-17, leptin, adiponectin, NLRP3 inflammasome, and TLR-4, have been implicated in the pathogenesis of lung disease. These mediators are known to be modulated by autophagy activity. In this perspective, we highlight the recent advances in the understanding of autophagy in obesity-related conditions, as well as the potential mechanisms that can link autophagy and obesity in the pathogenesis of lung disease.

Early-onset obesity dysregulates pulmonary adipocytokine/insulin signaling and induces asthma-like disease in mice

Childhood obesity is a risk factor for asthma, but the molecular mechanisms linking both remain elusive. Since obesity leads to chronic low-grade inflammation and affects metabolic signaling we hypothesized that postnatal hyperalimentation (pHA) induced by maternal high-fat-diet during lactation leads to early-onset obesity and dysregulates pulmonary adipocytokine/insulin signaling, resulting in metabolic programming of asthma-like disease in adult mice. Offspring with pHA showed at postnatal day 21 (P21): (1) early-onset obesity, greater fat-mass, increased expression of IL-1β, IL-23, and Tnf-α, greater serum leptin and reduced glucose tolerance than Control (Ctrl); (2) less STAT3/AMPKα-activation, greater SOCS3 expression and reduced AKT/GSK3β-activation in the lung, indicative of leptin resistance and insulin signaling, respectively; (3) increased lung mRNA of IL-6, IL-13, IL-17A and Tnf-α. At P70 body weight, fat-mass, and cytokine mRNA expression were similar in the pHA and Ctrl, but serum leptin and IL-6 were greater, and insulin signaling and glucose tolerance impaired. Peribronchial elastic fiber content, bronchial smooth muscle layer, and deposition of connective tissue were not different after pHA. Despite unaltered bronchial structure mice after pHA exhibited significantly increased airway reactivity. Our study does not only demonstrate that early-onset obesity transiently activates pulmonary adipocytokine/insulin signaling and induces airway hyperreactivity in mice, but also provides new insights into metabolic programming of childhood obesity-related asthma.

Low Plasma Levels of Adiponectin Do Not Explain Acute Respiratory Distress Syndrome Risk: a Prospective Cohort Study of Patients with Severe Sepsis

BACKGROUND

Obesity is associated with the development of acute respiratory distress syndrome (ARDS) in at-risk patients. Low plasma levels of adiponectin, a circulating hormone-like molecule, have been implicated as a possible mechanism for this association. The objective of this study was to determine the association of plasma adiponectin level at ICU admission with ARDS and 30-day mortality in patients with severe sepsis and septic shock.

METHODS

This is a prospective cohort study of patients admitted to the medical ICU at the Hospital of the University of Pennsylvania. Plasma adiponectin was measured at the time of ICU admission. ARDS was defined by Berlin criteria. Multivariable logistic regression was used to determine the association of plasma adiponectin with the development of ARDS and mortality at 30 days.

RESULTS

The study included 164 patients. The incidence of ARDS within 5 days of admission was 45%. The median initial plasma adiponectin level was 7.62 mcg/ml (IQR: 3.87, 14.90) in those without ARDS compared to 8.93 mcg/ml (IQR: 4.60, 18.85) in those developing ARDS. The adjusted odds ratio for ARDS associated with each 5 mcg increase in adiponectin was 1.12 (95% CI 1.01, 1.25), p-value 0.025). A total of 82 patients (51%) of the cohort died within 30 days of ICU admission. There was a statistically significant association between adiponectin and mortality in the unadjusted model (OR 1.11, 95% CI 1.00, 1.23, p-value 0.04) that was no longer significant after adjusting for potential confounders.

CONCLUSIONS

In this study, low levels of adiponectin were not associated with an increased risk of ARDS in patients with severe sepsis and septic shock. This argues against low levels of adiponectin as a mechanism explaining the association of obesity with ARDS. At present, it is unclear whether circulating adiponectin is involved in the pathogenesis of ARDS or simply represents an epiphenomenon of other unknown functions of adipose tissue or metabolic alterations in sepsis.

The independent association of platelet parameters with overall survival in pancreatic adenocarcinoma receiving intensity-modulated radiation therapy

BACKGROUND

Platelets are involved in multiple links of the process of thrombus formation and development. The aim of this study is to investigate the impact of pretreatment platelet parameters, such as plateletcrit (PCT), platelet mean distribution width (MDW), and mean platelet volume (MPV) in a cohort of patients with locally advanced pancreatic adenocarcinoma treated with a combination of chemotherapy and radiation therapy.

METHODS

A retrospective analysis was conducted of 163 locally advanced unresectable consecutive pancreatic adenocarcinoma patients who received chemoradiotherapy in Zhejiang cancer hospital from January 2009 to December 2011. The effects of platelet parameters on overall survival (OS) were assessed using Kaplan-Meier analysis. Independent prognostic factors were identified in the multivariate Cox analysis.

RESULTS

The median of the PC, PCT, MDW, MPV and CRP were 175×10(9), 20.0%, 14.0%, 10.8 fl and 7.0 mg/L, respectively. MDW was positively correlated with PC (r=0.156, P=0.047) and CRP (r=0.591, P<0.001). The median survival time of high MDW group was significantly worse than that of low MDW group (14.0 m Vs 11.0 m, P=0.008). Patients with high PCT were found to have shorter overall survival time (15.0 m Vs 11.0 m, P=0.018). Multivariate analysis indicated that MDW and N stage were two independent prognostic factors for overall survival (P<0.05). Patients with higher MDW had a 1.48-fold increased risk of death compared to those with low MDW.

CONCLUSIONS

MDW is an independent negative prognostic factor for overall survival in pancreatic adenocarcinoma patients.

C1q Deficiency Promotes Pulmonary Vascular Inflammation and Enhances the Susceptibility of the Lung Endothelium to Injury

The collectin proteins are innate immune molecules found in high concentrations on the epithelial and endothelial surfaces of the lung. While these proteins are known to have important anti-inflammatory actions in the airways of the lung little is known of their functional importance in the pulmonary circulation. We recently demonstrated that the circulating collectin protein adiponectin has potent anti-inflammatory effects on the lung endothelium, leading us to reason that other structurally related proteins might have similar effects. To test this hypothesis, we investigated the anti-inflammatory actions of C1q in lung endothelial homeostasis and the pulmonary vascular response to LPS or HCl injury. We show that lung endothelium from C1q-deficient (C1q(-/-)) mice expresses higher baseline levels of the vascular adhesion markers ICAM-1, VCAM-1, and E-selectin when compared with wild-type mice. Further, we demonstrate that these changes are associated with enhanced susceptibility of the lung to injury as evident by increased expression of adhesion markers, enhanced production of pro-inflammatory cytokines, and augmented neutrophil recruitment. Additionally, we found that C1q(-/-) mice also exhibited enhanced endothelial barrier dysfunction after injury as manifested by decreased expression of junctional adherens proteins and enhanced vascular leakage. Mechanistically, C1q appears to mediate its effects by inhibiting phosphorylation of p38 mitogen-activated protein kinase (MAPK) and blocking nuclear translocation of the P65 subunit of nuclear factor (NF)-κB. In summary, our findings indicate a previously unrecognized role for C1q in pulmonary vascular homeostasis and provide added support for the hypothesis that circulating collectin proteins have protective effects on the lung endothelium.