Protective effects of recombinant 53-kDa protein of Trichinella spiralis on acute lung injury in mice via alleviating lung pyroptosis by promoting M2 macrophage polarization

Trichinella spiralis represents an effective treatment for autoimmune and inflammatory diseases. The effects of recombinant T. spiralis (TS) 53-kDa protein (rTsP53) on acute lung injury (ALI) remain unclear. Here, mice were divided randomly into a control group, LPS group, and rTsP53 + LPS group. ALI was induced in BALB/c mice by LPS (10 mg/kg) injected via the tail vein. rTsP53 (200 µl; 0.4 μg/μl) was injected subcutaneously three times at an interval of 5 d before inducing ALI in the rTsP53+LPS group. Lung pathological score, the ratio and markers of classic activated macrophages (M1) and alternatively activated macrophages (M2), cytokine profiles in alveolar lavage fluid, and pyroptosis protein expression in lung tissue were investigated. RTsP53 decreased lung pathological score. Furthermore, rTsP53 suppressed inflammation by increasing IL-4, IL-10, and IL-13. There was an increase in alveolar M2 macrophage numbers, with an increase in CD206 and arginase-1-positive cells and a decrease in alveolar M1 markers such as CD197 and iNOS. In addition, the polarization of M2 macrophages induced by rTsP53 treatment could alleviate ALI by suppressing lung pyroptosis. RTsP53 was identified as a potential agent for treating LPS-induced ALI via alleviating lung pyroptosis by promoting M2 macrophage polarization.     

Silencing of Paralemmin-3 Protects Mice from lipopolysaccharide-induced acute lung injury

Excessive inflammatory response induced by lipopolysaccharide (LPS) plays a critical role in the development of acute lung injury (ALI). Paralemmin-3 (PALM3) is a novel protein that can modulate LPS-stimulated inflammatory responses in alveolar epithelial A549 cells. However, it remains unclear whether it is involved in the progression of ALI in vivo. Therefore, we studied the role of PALM3 in the pathogenesis of ALI induced by LPS. ALI was induced by LPS peritoneal injection in C57BL/6J mice. Lentivirus-mediated small interfering RNA (siRNA) targeting the mouse PALM3 gene and a negative control siRNA were intranasally administered to the mice. We found that the expression of PALM3 was up-regulated in the lung tissues obtained from the mouse model of LPS-induced ALI. The LPS-evoked inflammatory response (neutrophils and the concentrations of proinflammatory cytokines [IL-6, IL-1β, TNF-α, MIP-2] in the bronchoalveolar lavage fluid [BALF]), histologic lung injury (lung injury score), permeability of the alveolar capillary barrier (lung wet/dry weight ratio and BALF protein concentration) and mortality rates were attenuated in the PALM3 siRNA-treated mice. These results indicate that PALM3 contributes to the development of ALI in mice challenged with LPS. Inhibiting PALM3 through the intranasal application of specific siRNA protected against LPS-induced ALI.     

Role of CD69 in acute lung injury

AimsCD69 is an early activation marker in lymphocytes and an important signal transmitter in inflammatory processes. However, its role in acute lung injury (ALI) is still unknown. We used a lipopolysaccharide (LPS)-induced mouse model of ALI to study the role of macrophage-surface CD69 in this condition.Main methodsWe investigated bronchoalveolar lavage fluid (BALF) cell subpopulations, myeloperoxidase levels in lung homogenates, lung pathology, and lung oedema in CD69-deficient (CD69^?/?) mice 24 h after LPS instillation. We also determined cytokine/chemokine expression levels in BALF and macrophage culture supernatant from CD69^?/? and wild type (WT) mice. Also, we investigated CD69, keratinocyte-derived chemokine (KC) and macrophage inflammatory protein (MIP)-2 localization in the lungs after LPS administration. Furthermore, we examined the effect of anti-CD69 antibody on LPS-induced cytokine/chemokine release from cultured macrophages.Key findingsOur study shows that intratracheal instillation of LPS-induced neutrophilic infiltration, histopathological changes, myeloperoxidase positivity, and oedema in the lung to a lower degree in CD69^?/? mice than in WT mice. The immunoreactivities for CD69, KC and MIP2 were induced in the lung of WT mice instilled with LPS and were predominantly localized to the macrophages. Moreover, the cytokine/chemokine expression profile between the two genotypes of cultured macrophages in response to LPS was similar to that observed in the BALF. In addition, anti-CD69 antibody inhibited the LPS-induced cytokine/chemokine expression.SignificanceThese results suggest that CD69 on macrophages plays a crucial role in the progression of LPS-induced ALI and may be a potentially useful target in the therapy for ALI.     

Inhaled nitric oxide attenuates acute lung injury via inhibition of nuclear factor-kappa B and inflammation.

The effect of inhaled nitric oxide (NO) on inflammatory process in acute lung injury (ALI) is unclear. The aims of this study were to 1) examine whether inhaled NO affects the biochemical lung injury parameters and cellular inflammatory responses and 2) determine the effect of inhaled NO on the activation of nuclear factor-kappa B (NF-kappa B) in lipopolysaccharide (LPS)-induced ALI. Compared with saline controls, rabbits treated intravenously with LPS showed increases in total protein and lactate dehydrogenase in the bronchoalveolar lavage (BAL) fluid, indicating ALI. LPS-treated animals with NO inhalation (LPS-NO) showed significant decreases in these parameters. Neutrophil numbers in the BAL fluid, the activity of reactive oxygen species in BAL cells, and the levels of interleukin (IL)-1 beta and IL-8 in alveolar macrophages were increased in LPS-treated animals. In contrast, neutrophil numbers and these cellular activities were substantially decreased in LPS-NO animals, compared with LPS-treated animals. NF-kappa B activation in alveolar macrophages from LPS-treated animals was also markedly increased, whereas this activity was effectively blocked in LPS-NO animals. These results suggest that inhaled NO attenuates LPS-induced ALI and pulmonary inflammation. This attenuation may be associated with the inhibition of NF-kappa B activation.     

Endothelial Nitric Oxide Synthase Deficient Mice Are Protected from Lipopolysaccharide Induced Acute Lung Injury

Lipopolysaccharide (LPS) derived from the outer membrane of gram-negative bacteria induces acute lung injury (ALI) in mice. This injury is associated with lung edema, inflammation, diffuse alveolar damage, and severe respiratory insufficiency. We have previously reported that LPS-mediated nitric oxide synthase (NOS) uncoupling, through increases in asymmetric dimethylarginine (ADMA), plays an important role in the development of ALI through the generation of reactive oxygen and nitrogen species. Therefore, the focus of this study was to determine whether mice deficient in endothelial NOS (eNOS^-/-) are protected against ALI. In both wild-type and eNOS^-/- mice, ALI was induced by the intratracheal instillation of LPS (2 mg/kg). After 24 hours, we found that eNOS^-/-mice were protected against the LPS mediated increase in inflammatory cell infiltration, inflammatory cytokine production, and lung injury. In addition, LPS exposed eNOS^-/- mice had increased oxygen saturation and improved lung mechanics. The protection in eNOS^-/- mice was associated with an attenuated production of NO, NOS derived superoxide, and peroxynitrite. Furthermore, we found that eNOS^-/- mice had less RhoA activation that correlated with a reduction in RhoA nitration at Tyr³⁴. Finally, we found that the reduction in NOS uncoupling in eNOS^-/- mice was due to a preservation of dimethylarginine dimethylaminohydrolase (DDAH) activity that prevented the LPS-mediated increase in ADMA. Together our data suggest that eNOS derived reactive species play an important role in the development of LPS-mediated lung injury.     

Adrenomedullin expression in a rat model of acute lung injury induced by hypoxia and LPS

Adrenomedullin (ADM) is upregulated independently by hypoxia and LPS, two key factors in the pathogenesis of acute lung injury (ALI). This study evaluates the expression of ADM in ALI using experimental models combining both stimuli: an in vivo model of rats treated with LPS and acute normobaric hypoxia (9% O2) and an in vitro model of rat lung cell lines cultured with LPS and exposed to hypoxia (1% O2). ADM expression was analyzed by in situ hybridization, Northern blot, Western blot, and RIA analyses. In the rat lung, combination of hypoxia and LPS treatments overcomes ADM induction occurring after each treatment alone. With in situ techniques, the synergistic effect of both stimuli mainly correlates with ADM expression in inflammatory cells within blood vessels and, to a lesser extent, to cells in the lung parenchyma and bronchiolar epithelial cells. In the in vitro model, hypoxia and hypoxia + LPS treatments caused a similar strong induction of ADM expression and secretion in epithelial and endothelial cell lines. In alveolar macrophages, however, LPS-induced ADM expression and secretion were further increased by the concomitant exposure to hypoxia, thus paralleling the in vivo response. In conclusion, ADM expression is highly induced in a variety of key lung cell types in this rat model of ALI by combination of hypoxia and LPS, suggesting an essential role for this mediator in this syndrome.     

Resolution of experimental lung injury by monocyte-derived inducible nitric oxide synthase

Although early events in the pathogenesis of acute lung injury (ALI) have been defined, little is known about the mechanisms mediating resolution. To search for determinants of resolution, we exposed wild type (WT) mice to intratracheal LPS and assessed the response at intervals to day 10, when injury had resolved. Inducible NO synthase (iNOS) was significantly upregulated in the lung at day 4 after LPS. When iNOS(-/-) mice were exposed to intratracheal LPS, early lung injury was attenuated; however, recovery was markedly impaired compared with WT mice. iNOS(-/-) mice had increased mortality and sustained increases in markers of lung injury. Adoptive transfer of WT (iNOS(+/+)) bone marrow-derived monocytes or direct adenoviral gene delivery of iNOS into injured iNOS(-/-) mice restored resolution of ALI. Irradiated bone marrow chimeras confirmed the protective effects of myeloid-derived iNOS but not of epithelial iNOS. Alveolar macrophages exhibited sustained expression of cosignaling molecule CD86 in iNOS(-/-) mice compared with WT mice. Ab-mediated blockade of CD86 in iNOS(-/-) mice improved survival and enhanced resolution of lung inflammation. Our findings show that monocyte-derived iNOS plays a pivotal role in mediating resolution of ALI by modulating lung immune responses, thus facilitating clearance of alveolar inflammation and promoting lung repair.     

miR-146b overexpression ameliorates lipopolysaccharide-induced acute lung injury in vivo and in vitro

Acute respiratory distress syndrome (ARDS) is a type of acute lung injury (ALI), which causes high morbidity and mortality. So far, effective clinical treatment of ARDS is still limited. Recently, miR-146b has been reported to play a key role in inflammation. In the present study, we evaluated the functional role of miR-146b in ARDS using the murine model of lipopolysaccharide (LPS)-induced ALI. The miR-146b expression could be induced by LPS stimulation, and miR-146b overexpression was required in the maintenance of body weight and survival of ALI mice; after miR-146b overexpression, LPS-induced lung injury, pulmonary inflammation, total cell and neutrophil counts, proinflammatory cytokines, and chemokines in bronchial alveolar lavage (BAL) fluid were significantly reduced. The promotive effect of LPS on lung permeability through increasing total protein, albumin and IgM in BAL fluid could be partially reversed by miR-146b overexpression. Moreover, in murine alveolar macrophages, miR-146b overexpression reduced LPS-induced TNF-α and interleukin (IL)-1β releasing. Taken together, we demonstrated that miR-146b overexpression could effectively improve the LPS-induced ALI; miR-146b is a promising target in ARDS treatment.     

Targeting myeloid differentiation protein 2 by the new chalcone L2H21 protects LPS‐induced acute lung injury

Acute inflammatory diseases are the leading causes of mortality in intensive care units. Myeloid differentiation 2 (MD‐2) is required for recognizing lipopolysaccharide (LPS) by toll‐like receptor 4 (TLR4), and represents an attractive therapeutic target for LPS‐induced inflammatory diseases. In this study, we report a chalcone derivative, L2H21, as a new MD2 inhibitor, which could inhibit LPS‐induced inflammation both in vitro and in vivo. We identify that L2H21 as a direct inhibitor of MD‐2 by binding to Arg⁹⁰ and Tyr¹⁰² residues in MD‐2 hydrophobic pocket using a series of biochemical experiments, including surface plasmon response, molecular docking and amino acid mutation. L2H21 dose dependently inhibited LPS‐induced inflammatory cytokine expression in primary macrophages. In mice with LPS intratracheal instillation, L2H21 significantly decreased LPS‐induced pulmonary oedema, pathological changes in lung tissue, protein concentration increase in bronchoalveolar lavage fluid, inflammatory cells infiltration and inflammatory gene expression, accompanied with the decrease in pulmonary TLR4/MD‐2 complex. Meanwhile, administration with L2H21 protects mice from LPS‐induced mortality at a degree of 100%. Taken together, this study identifies a new MD2 inhibitor L2H21 as a promising candidate for the treatment of acute lung injury (ALI) and sepsis, and validates that inhibition of MD‐2 is a potential therapeutic strategy for ALI.     

NALP-3 inflammasome silencing attenuates ceramide-induced transepithelial permeability

The hallmark of acute lung injury (ALI) is the influx of proinflammatory cytokines into lung tissue and alveolar permeability that ultimately leads to pulmonary edema. However, the mechanisms involved in inflammatory cytokine production and alveolar permeability are unclear. Recent studies suggest that excessive production of ceramide has clinical relevance as a mediator of pulmonary edema and ALI. Our earlier studies indicate that the activation of inflammasome promotes the processing and secretion of proinflammatory cytokines and causes alveolar permeability in ALI. However, the role of ceramide in inflammasome activation and the underlying mechanism in relation to alveolar permeability is not known. We hypothesized that ceramide activates the inflammasome and causes inflammatory cytokine production and alveolar epithelial permeability. To test this hypothesis, we analyzed the lung ceramide levels during hyperoxic ALI in mice. The effect of ceramide on activation of inflammasome and production of inflammatory cytokine was assessed in primary mouse alveolar macrophages and THP-1 cells. Alveolar transepithelial permeability was determined in alveolar epithelial type-II cells (AT-II) and THP-1 co-cultures. Our results reveal that ceramide causes inflammasome activation, induction of caspase-1, IL-1β cleavage, and release of proinflammatory cytokines. In addition, ceramide further induces alveolar epithelial permeability. Short-hairpin RNA silencing of inflammasome components abrogated ceramide-induced secretion of proinflammatory cytokines in vitro. Inflammasome silencing abolishes ceramide-induced alveolar epithelial permeability in AT-II. Collectively, our results demonstrate for the first time that ceramide-induced secretion of proinflammatory cytokines and alveolar epithelial permeability occurs though inflammasome activation.     

Role of resident alveolar macrophages in leukocyte traffic into the alveolar air space of intact mice

Intratracheal instillation of the monocyte chemoattractant JE/monocyte chemoattractant protein (MCP)-1 in mice was recently shown to cause increased alveolar monocyte accumulation in the absence of lung inflammation, whereas combined JE/MCP-1/lipopolysaccharide (LPS) challenge provoked acute lung inflammation with early alveolar neutrophil and delayed alveolar monocyte influx. We evaluated the role of resident alveolar macrophages (rAM) in these leukocyte recruitment events and related phenomena of lung inflammation. Depletion of rAM by pretreatment of mice with liposomal clodronate did not affect the JE/MCP-1-driven alveolar monocyte accumulation, despite the observation that rAM constitutively expressed the JE/MCP-1 receptor CCR2, as analyzed by flow cytometry and immunohistochemistry. In contrast, depletion of rAM largely suppressed alveolar cytokine release as well as neutrophil and monocyte recruitment profiles upon combined JE/MCP-1/LPS treatment. Despite this strongly attenuated alveolar inflammatory response, increased lung permeability was still observed in rAM-depleted mice undergoing JE/MCP-1/LPS challenge. Lung leakage was abrogated by codepletion of circulating neutrophils or administration of anti-CD18. Collectively, rAM are not involved in JE/MCP-1-driven alveolar monocyte recruitment in noninflamed lungs but largely contribute to the alveolar cytokine response and enhanced early neutrophil and delayed monocyte influx under inflammatory conditions (JE/MCP-1/LPS deposition). Loss of lung barrier function observed under these conditions is rAM independent but involves circulating neutrophils via beta(2)-integrin engagement.     

Macrophages mediate lung inflammation in a mouse model of ischemic acute kidney injury

Serum IL-6 is increased in acute kidney injury (AKI) and inhibition of IL-6 reduces AKI-mediated lung inflammation. We hypothesized that circulating monocytes produce IL-6 and that alveolar macrophages mediate lung inflammation after AKI via chemokine (CXCL1) production. To investigate systemic and alveolar macrophages in lung injury after AKI, sham operation or 22 min of renal pedicle clamping (AKI) was performed in three experimental settings: 1) systemic macrophage depletion via diphtheria toxin (DT) injection to CD11b-DTR transgenic mice, 2) DT injection to wild-type mice, and 3) alveolar macrophage depletion via intratracheal (IT) liposome-encapsulated clodronate (LEC) administration to wild-type mice. In mice with AKI and systemic macrophage depletion (CD11b-DTR transgenic administered DT) vs. vehicle-treated AKI, blood monocytes and lung interstitial macrophages were reduced, renal function was similar, serum IL-6 was increased, lung inflammation was improved, lung CXCL1 was reduced, and lung capillary leak was increased. In wild-type mice with AKI administered DT vs. vehicle, serum IL-6 was increased. In mice with AKI and alveolar macrophage depletion (IT-LEC) vs. AKI with normal alveolar macrophage content, blood monocytes and lung interstitial macrophages were similar, alveolar macrophages were reduced, renal function was similar, lung inflammation was improved, lung CXCL1 was reduced, and lung capillary leak was increased. In conclusion, administration of DT in AKI is proinflammatory, limiting the use of the DTR-transgenic model to study systemic effects of AKI. Mice with AKI and either systemic mononuclear phagocyte depletion or alveolar macrophage depletion had reduced lung inflammation and lung CXCL1, but increased lung capillary leak; thus, mononuclear phagocytes mediate lung inflammation, but they protect against lung capillary leak after ischemic AKI. Since macrophage activation and chemokine production are key events in the development of acute lung injury (ALI), these data provide further evidence that AKI may cause ALI.     

Mucin1 relieves acute lung injury by inhibiting inflammation and oxidative stress

Acute lung injury/acute respiratory distress syndrome (ALI/ARDS) is a kind of diffuse inflammatory injury caused by various factors, characterized by respiratory distress and progressive hypoxemia. It is a common clinical critical illness. The aim of this study was to investigate the effect and mechanism of the Mucin1 (MUC1) gene and its recombinant protein on lipopolysaccharide (LPS)-induced ALI/ARDS. We cultured human alveolar epithelial cell line (BEAS-2B) and used MUC1 overexpression lentivirus to detect the effect of MUC1 gene on BEAS-2B cells. In addition, we used LPS to induce ALI/ARDS in C57/BL6 mice and use hematoxylin and eosin (H&E) staining to verify the effect of their modeling. Recombinant MUC1 protein was injected subcutaneously into mice. We examined the effect of MUC1 on ALI/ARDS in mice by detecting the expression of inflammatory factors and oxidative stress molecules in mouse lung tissue, bronchoalveolar lavage fluid (BALF) and serum. Overexpression of MUC1 effectively ameliorated LPS-induced damage to BEAS-2B cells. Results of H&E staining indicate that LPS successfully induced ALI/ARDS in mice and MUC1 attenuated lung injury. MUC1 also reduced the expression of inflammatory factors (IL-1β, TNF-α, IL-6 and IL-8) and oxidative stress levels in mice. In addition, LPS results in an increase in the activity of the TLR4/NF-κB signaling pathway in mice, whereas MUC1 decreased the expression of the TLR4/NF-κB signaling pathway. MUC1 inhibited the activity of TLR4/NF-κB signaling pathway and reduced the level of inflammation and oxidative stress in lung tissue of ALI mice.Key words: Mucin1, acute lung injury, inflammation, oxidative stress, TLR4/NF-κB     

The role of mitogen-activated protein kinase phosphatase-1 in the response of alveolar macrophages to lipopolysaccharide: attenuation of proinflammatory cytokine biosynthesis via feedback control of p38

Mitogen-activated protein (MAP) kinases are critical mediators of innate immune responses. In response to lipopolysaccharide (LPS), MAP kinases are rapidly activated and play an important role in the production of proinflammatory cytokines. Although a number of MAP kinase phosphatases (MKPs) have been identified, their roles in the control of cytokine production have not been well defined. In the present report, we investigated the role of MKP-1 in alveolar macrophages stimulated with LPS. We found that LPS triggered transient activation of three MAP kinase subfamilies, ERK, JNK, and p38, in both immortalized and primary murine alveolar macrophages. MKP-1 was rapidly induced by LPS, and its induction correlated with the dephosphorylation of these MAP kinases. Blocking MKP-1 with triptolide prolonged the activities of both JNK and p38 in immortalized alveolar macrophages. Stimulation of primary alveolar macrophages isolated from MKP-1-deficient mice with LPS resulted in a prolonged p38 phosphorylation compared with wild type alveolar macrophages. Accordingly, these MKP-1-deficient alveolar macrophages also mounted a more robust and rapid tumor necrosis factor alpha production than their wild type counterparts. Adenovirus-mediated MKP-1 overexpression significantly attenuated tumor necrosis factor alpha production in immortalized alveolar macrophages. Finally, MKP-1 was induced by a group of corticosteroids frequently prescribed for the treatment of inflammatory lung diseases, and the anti-inflammatory potencies of these drugs closely correlated with their abilities to induce MKP-1. Our studies indicated that MKP-1 plays an important role in dampening the inflammatory responses of alveolar macrophages. We speculate that MKP-1 may represent a novel target for therapeutic intervention of inflammatory lung diseases.     

辛伐他汀对急性肺损伤及囊性纤维化跨膜传导调节体表达的影响

目的:探讨辛伐他汀对急性肺损伤大鼠囊性纤维化跨膜传导调节体(CFTR氯离子通道)的影响及其对减轻急性肺损伤的作用。方法:40只雄性SD大鼠随机分为空白组、模型组、辛伐他汀低剂量组(20 mg/kg)、辛伐他汀中剂量组(40 mg/kg)、辛伐他汀高剂量组(80 mg/kg);气道内滴注脂多糖(10 mg/kg)制备急性肺损伤模型。进行肺湿/干重比、肺泡灌洗液蛋白检测,HE染色观察肺组织的病理变化;实时荧光定量PCR检测肺组织匀浆CFTR mRNA表达。结果:结果显示,模型组的肺湿干重比,肺泡灌洗液蛋白较空白组高(P0.05),病理示肺泡膈增厚,大量炎性细胞浸润,肺泡腔内可见红细胞及血肿,提示模型复制成功。辛伐他汀低剂量组的肺湿/干重比、肺泡灌洗液蛋白与模型组相比无明显差异,病理可见肺损伤较重,与模型组相比无改善;CFTR mRNA表达与模型组相比稍高但无明显差异(P0.05)。辛伐他汀中高剂量组中肺湿/干重比、肺泡灌洗液蛋白与模型组相比有所降低,肺组织CFTRmRNA表达较模型组明显增加(P0.05),但中高剂量组之间无明显差异(P0.05);病理可见肺泡膈增厚,极少见炎性细胞浸润及透明膜,肺泡腔内未见明显出血和水肿,肺损伤程度较模型组减轻。结论:中高剂量的辛伐他汀(40 mg/kg)对急性肺损伤有一定保护作用,并上调CFTR的表达。     

Inhibition of glycolysis alleviates lipopolysaccharide-induced acute lung injury in a mouse model

Gluconic metabolic reprogramming, immune response, and inflammation are intimately linked. Glycolysis involves in the pathologic progress in acute and chronic inflammatory diseases. However, the involvement of glycolysis in the acute lung injury (ALI) is still unclear. This study investigated the role of glycolysis in an animal model of ALI. First, we found that lactate content in serum was remarkably increased in ALI patients and a murine model induced by intratracheal administration of lipopolysaccharide (LPS). The key proteins involving in glycolysis were robustly elevated, including HK2, PKM2, and HIF-1α. Intriguingly, inhibition of glycolysis by 2-deoxyglucose (2-DG) pronouncedly attenuated the lung tissue pathological injury, accumulation of neutrophil, oxidative stress, expression of proinflammatory factors in the lung of ALI mice induced by LPS. The 2-DG treatment also strongly suppressed the activation of the NOD-like receptor (NLR) family and pyrin domain-containing protein 3 (NLRP3) inflammasome. Furthermore, we investigated the role of glycolysis in the inflammatory response of primary murine macrophages activated by LPS in vitro. We found that the 2-DG treatment remarkably reduced the expression of proinflammatory factors induced by LPS, including tumor necrosis factor-α messenger RNA (mRNA), pro-interleukin (IL)-1β mRNA, pro-IL-18 mRNA, NLRP3 mRNA, caspase-1 mRNA, and IL-1β protein. Altogether, these data provide a novel link between gluconic metabolism reprogramming and uncontrolled inflammatory response in ALI. This study suggests glycolytic inhibition as an effective anti-inflammatory strategy in treating ALI.     

Adiponectin attenuates lipopolysaccharide-induced acute lung injury through suppression of endothelial cell activation

Adiponectin (APN) is an adipose tissue-derived factor with anti-inflammatory and vascular protective properties whose levels paradoxically decrease with increasing body fat. In this study, APN's role in the early development of ALI to LPS was investigated. Intratracheal LPS elicited an exaggerated systemic inflammatory response in APN-deficient (APN(-/-)) mice compared with wild-type (wt) littermates. Increased lung injury and inflammation were observed in APN(-/-) mice as early as 4 h after delivery of LPS. Targeted gene expression profiling performed on immune and endothelial cells isolated from lung digests 4 h after LPS administration showed increased proinflammatory gene expression (e.g., IL-6) only in endothelial cells of APN(-/-) mice when compared with wt mice. Direct effects on lung endothelium were demonstrated by APN's ability to inhibit LPS-induced IL-6 production in primary human endothelial cells in culture. Furthermore, T-cadherin-deficient mice that have significantly reduced lung airspace APN but high serum APN levels had pulmonary inflammatory responses after intratracheal LPS that were similar to those of wt mice. These findings indicate the importance of serum APN in modulating LPS-induced ALI and suggest that conditions leading to hypoadiponectinemia (e.g., obesity) predispose to development of ALI through exaggerated inflammatory response in pulmonary vascular endothelium.     

Angiogenic growth factors in the pathophysiology of a murine model of acute lung injury

Capillary leakage and alveolar edema are hallmarks of acute lung injury (ALI). Neutrophils and serum macromolecules enter alveoli, promoting inflammation. Vascular endothelial growth factor (VEGF) causes plasma leakage in extrapulmonary vessels. Angiopoietin (Ang)-1 and -4 stabilize vessels, attenuating capillary leakage. We hypothesized that VEGF and Ang-1 and -4 modulate vessel leakage in the lung, contributing to the pathogenesis of ALI. We examined a murine model of lipopolysaccharide (LPS)-induced ALI. C57BL/6 and 129/J mice were studied at baseline and 24, 48, and 96 h after single or multiple doses of aerosolized LPS. Both strains exhibited time- and dose-dependent increases in inflammation and a deterioration of lung mechanics. Bronchoalveolar lavage (BAL) protein levels increased significantly, suggesting capillary leakage. Increased BAL neutrophil and total protein content correlated with time-dependent increased tissue VEGF and decreased Ang-1 and -4 levels, with peak VEGF and minimum Ang-1 and -4 expression after 96 h of LPS challenge. These data suggest that changes in the balance between VEGF and Ang-1 and -4 after LPS exposure may modulate neutrophil influx, protein leakage, and alveolar flooding during early ALI.