Inhibition of the Src and Jak Kinases Protects against Lipopolysaccharide-induced Acute Lung Injury

Bosutinib mitigates inflammation in experimental sepsis

BACKGROUND

Sepsis, a leading cause of death globally, lacks targeted and effective treatment. Its pathophysiology involves unbalanced inflammation, marked by a high release of inflammatory mediators, leukocyte recruitment, vascular changes and dysfunction of the nervous and respiratory systems. Src family tyrosine kinases (SFK) play a critical role in immune responses, and their inhibition can modulate excessive inflammation. This study investigates the potential of bosutinib, an SFK inhibitor, as a treatment for sepsis.

METHODS

Clinical signs, survival rates, systemic and neuronal inflammatory responses, cell recruitment, lung function and cerebral microcirculation were analysed in mice treated with bosutinib (3 mg/kg) or DMSO/saline followed by cecal ligation and puncture (CLP)-induced sepsis.

RESULTS

Bosutinib treatment reduced the severity of sepsis, improved survival rates and reduced the levels of pro-inflammatory cytokines and chemokines in peritoneal lavage, plasma and brain tissue. It also reduced cellular infiltration and bacterial growth at the infection site and protected lung function by reducing diffuse alveolar damage. Using intravital microscopy and laser speckle techniques, bosutinib improved capillary density and blood perfusion and reduced leukocyte recruitment and adhesion in the cerebral microcirculation of septic animals.

CONCLUSIONS

Bosutinib pretreatment attenuated dysregulated inflammatory responses and neurovascular changes in experimental sepsis.

Proinflammatory Cytokines in Chronic Respiratory Diseases and Their Management

Pulmonary homeostasis can be agitated either by external environmental insults or endogenous factors produced during respiratory/pulmonary diseases. The lungs counter these insults by initiating mechanisms of inflammation as a localized, non-specific first-line defense response. Cytokines are small signaling glycoprotein molecules that control the immune response. They are formed by numerous categories of cell types and induce the movement, growth, differentiation, and death of cells. During respiratory diseases, multiple proinflammatory cytokines play a crucial role in orchestrating chronic inflammation and structural changes in the respiratory tract by recruiting inflammatory cells and maintaining the release of growth factors to maintain inflammation. The issue aggravates when the inflammatory response is exaggerated and/or cytokine production becomes dysregulated. In such instances, unresolving and chronic inflammatory reactions and cytokine production accelerate airway remodeling and maladaptive outcomes. Pro-inflammatory cytokines generate these deleterious consequences through interactions with receptors, which in turn initiate a signal in the cell, triggering a response. The cytokine profile and inflammatory cascade seen in different pulmonary diseases vary and have become fundamental targets for advancement in new therapeutic strategies for lung diseases. There are considerable therapeutic approaches that target cytokine-mediated inflammation in pulmonary diseases; however, blocking specific cytokines may not contribute to clinical benefit. Alternatively, broad-spectrum anti-inflammatory approaches are more likely to be clinically effective. Herein, this comprehensive review of the literature identifies various cytokines (e.g., interleukins, chemokines, and growth factors) involved in pulmonary inflammation and the pathogenesis of respiratory diseases (e.g., asthma, chronic obstructive pulmonary, lung cancer, pneumonia, and pulmonary fibrosis) and investigates targeted therapeutic treatment approaches.

Unphysiological lung strain promotes ventilation-induced lung injury via activation of the PECAM-1/Src/STAT3 signaling pathway

Introduction

In patients with acute respiratory distress syndrome, mechanical ventilation often leads to ventilation-induced lung injury (VILI), which is attributed to unphysiological lung strain (UPLS) in respiratory dynamics. Platelet endothelial cell adhesion molecule-1 (PECAM-1), a transmembrane receptor, senses mechanical signals. The Src/STAT3 pathway plays a crucial role in the mechanotransduction network, concurrently triggering pyroptosis related inflammatory responses. We hypothesized that the mechanical stretch caused by UPLS can be sensed by PECAM-1 in the lungs, leading to VILI via the Src/STAT3 and pyroptosis pathway.

Methods

A VILI model was established in rats through UPLS. The link between lung strain and VILI as well as the change in the activation of PECAM-1, Src/STAT3, and pyroptosis was firstly being explored. Then, the inhibitors of PECAM-1, Src, STAT3 were adopted respectively, the effect on VILI, inflammation, the Src/STAT3 pathway, and pyroptosis was evaluated. In vitro, human umbilical vein endothelial cells (HUVECs) were used to validate the findings in vivo.

Results

UPLS activated PECAM-1, Src/STAT3 signaling pathway, inflammation, and pyroptosis in the VILI model with rats, whereas inhibition of PECAM-1 or the Src/STAT3 signaling pathway decreased lung injury, inflammatory responses, and pyroptosis. Inhibition of PECAM-1 also reduced activation of the Src/STAT3 signaling pathway. The mechanism was validated with HUVECs exposed to overload mechanical cyclic stretch.

Conclusions

This study suggests that UPLS contributes to VILI by activating the PECAM-1/Src/STAT3 pathway and inducing inflammatory responses as well aspyroptosis.

Future Directions in Therapies for Acute Respiratory Distress Syndrome

Acute respiratory distress syndrome (ARDS) is caused by a complex interplay among hyperinflammation, endothelial dysfunction, and alveolar epithelial injury. Targeted treatments toward the underlying pathways have been unsuccessful in unselected patient populations. The first reliable biological subphenotypes reflective of these biological disease states have been identified in the past decade. Subphenotype targeted intervention studies are needed to advance the pharmacologic treatment of ARDS.

Repression of JAK2-STAT1 and PD-L1 by CEP-33779 ameliorates the LPS-induced decline in phagocytic activity of alveolar macrophages and mitigates lung injury in mice

Background

The role of the JAK2-STAT1/PD-L1 pathway in the phagocytic activity of alveolar macrophages (AMs) during LPS-induced acute lung injury in mice remains poorly understood. This study aims to explore whether the JAK2-STAT1/PD-L1 pathway is upregulated on AMs in LPS-induced mice acute lung injury and to further explore the impact of the JAK2-specific inhibitor CEP-33779 on the LPS-induced impairment of AMs phagocytic activity and lung injury.

Methods

ALI was induced in mice via intratracheal administration of LPS, followed by intragastric administration of JAK2 inhibitor CEP-33779 suspension. Immunohistochemistry was conducted to assess PD-L1 expression in lung tissue, as well as p-JAK2, p-STAT1, and PD-L1 expression on AMs in bronchoalveolar lavage fluid (BALF) using immunofluorescence. Levels of TNF-α and IL-6, as well as protein concentration in BALF, were measured using enzyme-linked immunosorbent assay and Bicinchoninic acid assays, respectively. Hematoxylin-eosin staining and lung injury score were employed to evaluate pathological changes in mouse lungs. Total cell count in BALF was determined using a cell counter. Furthermore, western blot and immunofluorescence was conducted to assess the effect of JAK2 and STAT1 inhibitor on JAK2-STAT1 pathway activation and PD-L1 expression, while confocal microscopy with latex beads rabbit IgG FITC complex was used to observe MH-S cells phagocytic ability.

Results

The study revealed that LPS stimulation triggered the activation of the JAK2-STAT1 pathway and an upregulation of PD-L1 on AMs in both LPS-induced acute lung injury mice and MH-S cell lines. Moreover, treatment with the JAK2 and STAT1 inhibitor effectively reduced the activation of JAK2-STAT1 signaling, downregulated PD-L1 expression on AMs in BALF from LPS-induced ALI mice and LPS-stimulated MH-S cells, and significantly improved the LPS-induced reduction in phagocytic activity in MH-S cells. Most notably, CEP-33779 treatment significantly mitigated the pulmonary inflammatory response and lung injury in mice with LPS-induced ALI.

Conclusions

Collectively, these findings imply that the JAK2-STAT1 pathway plays a role in the upregulation of PD-L1, which in turn is associated with the diminished phagocytic activity in LPS-induced AMs as well as lung injury. Furthermore, our study highlights that CEP-33779 treatment can effectively improve the reduced phagocytic activity of AMs and relieve lung injury induced by LPS through suppression of the JAK2-STAT1/PD-L1 pathway.

Ophiopogonin D alleviates acute lung injury by regulating inflammation via the STAT3/A20/ASK1 axis

BACKGROUND

Acute lung injury (ALI) is characterized by acute pulmonary inflammatory infiltration. Alveolar epithelial cells (AECs) release numerous pro-inflammatory cytokines, which result in the pathological changes seen in ALI. Ophiopogonin D (OD), extracted from the roots of Ophiopogon japonicus (Thunb.) Ker Gawl. (Liliaceae), reduces inflammation; however, the efficacy of OD in ALI has not been reported and the underlying molecular mechanisms remain unclear.

PURPOSE

This study investigated the anti-inflammatory effects of OD, as well as the underlying mechanisms, in AECs and a mouse ALI model.

METHODS

Lipopolysaccharide (LPS) and tumor necrosis factor-α (TNF-α) were used to stimulate macrophages and A549 cells, and a mouse ALI model was established by intratracheal LPS administration. The anti-inflammatory effects and mechanisms of OD in the TNF-α-induced in vitro inflammation model was evaluated using real-time quantitative polymerase chain reaction qPCR), enzyme-linked immunosorbent assay (ELISA), western blotting, nuclear and cytoplasmic protein extraction, and immunofluorescence. The in vivo anti-inflammatory activity of OD was evaluated using hematoxylin and eosin staining, qPCR, ELISA, and western blotting.

RESULTS

The bronchoalveolar lavage fluid and lung tissue of LPS-induced ALI mice exhibited increased TNF-α expression. TNF-α induced a significantly greater pro-inflammatory effect in AECs than LPS. OD reduced inflammation and mitogen-activated protein kinase (MAPK) and transcription factor p65 phosphorylation in vivo and in vitro and promoted signal transducer and activator of transcription 3 (STAT3) phosphorylation and A20 expression, thereby inducing apoptosis signal-regulating kinase 1 (ASK1) proteasomal degradation.

CONCLUSION

OD exerts an anti-inflammatory effect by promoting STAT3-dependent A20 expression and ASK1 degradation. OD may therefore have therapeutic value in treating ALI and other TNF-α-related inflammatory diseases.

Efficacy and safety of an inhaled pan-Janus kinase inhibitor, nezulcitinib, in hospitalised patients with COVID-19: results from a phase 2 clinical trial

BACKGROUND

The inhaled lung-selective pan-Janus kinase inhibitor nezulcitinib had favourable safety and potential efficacy signals in part 1 of a phase 2 trial in patients with severe COVID-19, supporting progression to part 2.

METHODS

Part 2 was a randomised, double-blind phase 2 study (NCT04402866). Hospitalised patients aged 18-80 years with confirmed symptomatic COVID-19 requiring supplemental oxygen (excluding baseline invasive mechanical ventilation) were randomised 1:1 to nebulised nezulcitinib 3 mg or placebo for up to 7 days with background standard-of-care therapy (including corticosteroids). Efficacy endpoints included respiratory failure-free (RFF) days through day 28 as the primary endpoint. Secondary endpoints included safety and change from baseline oxygen saturation (SaO2)/fraction of inspired oxygen (FiO2) ratio on day 7, and 28-day mortality rate was a prespecified exploratory endpoint.

RESULTS

Between June 2020 and April 2021, 205 patients were treated (nezulcitinib, 103; placebo, 102). There was no statistically significant difference between nezulcitinib versus placebo in the primary endpoint (RFF days; median, 21.0 vs 21.0; p=0.6137) or secondary efficacy endpoints. Nezulcitinib was generally well tolerated with a favourable safety profile.

CONCLUSIONS

Although the prespecified primary, secondary and exploratory efficacy endpoints, including RFF through day 28, change from baseline SaO2/FiO2 ratio on day 7, and 28-day mortality rate, were not met, nezulcitinib was generally well tolerated and had a favourable safety profile. Further studies are required to determine if treatment with nezulcitinib confers clinical benefit in specific inflammatory biomarker-defined populations of patients with COVID-19.

JAK-STAT signaling as an ARDS therapeutic target: Status and future trends

Acute respiratory distress syndrome (ARDS) is characterized by noncardiogenic pulmonary edema. It has a high mortality rate and lacks effective pharmacotherapy. With the outbreak of COVID-19 worldwide, the mortality of ARDS has increased correspondingly, which makes it urgent to find effective targets and strategies for the treatment of ARDS. Recent clinical trials of Janus kinase (JAK) inhibitors in treating COVID-19-induced ARDS have shown a positive outcome, which makes the Janus kinase/signal transducer and activator of transcription (JAK/STAT) pathway a potential therapeutic target for treating ARDS. Here, we review the complex cause of ARDS, the molecular JAK/STAT pathway involved in ARDS pathology, and the progress that has been made in strategies targeting JAK/STAT to treat ARDS. Specifically, JAK/STAT signaling directly participates in the progression of ARDS or colludes with other pathways to aggravate ARDS. We summarize JAK and STAT inhibitors with ARDS treatment benefits, including inhibitors in clinical trials and preclinical studies and natural products, and discuss the side effects of the current JAK inhibitors to reveal future trends in the design of JAK inhibitors, which will help to develop effective treatment strategies for ARDS in the future.

Airway basal cells show a dedifferentiated KRT17highPhenotype and promote fibrosis in idiopathic pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) is a fatal disease with limited treatment options. In this study, we focus on the properties of airway basal cells (ABC) obtained from patients with IPF (IPF-ABC). Single cell RNA sequencing (scRNAseq) of bronchial brushes revealed extensive reprogramming of IPF-ABC towards a KRT17high PTENlow dedifferentiated cell type. In the 3D organoid model, compared to ABC obtained from healthy volunteers, IPF-ABC give rise to more bronchospheres, de novo bronchial structures resembling lung developmental processes, induce fibroblast proliferation and extracellular matrix deposition in co-culture. Intratracheal application of IPF-ABC into minimally injured lungs of Rag2-/- or NRG mice causes severe fibrosis, remodeling of the alveolar compartment, and formation of honeycomb cyst-like structures. Connectivity MAP analysis of scRNAseq of bronchial brushings suggested that gene expression changes in IPF-ABC can be reversed by SRC inhibition. After demonstrating enhanced SRC expression and activity in these cells, and in IPF lungs, we tested the effects of saracatinib, a potent SRC inhibitor previously studied in humans. We demonstrate that saracatinib modified in-vitro and in-vivo the profibrotic changes observed in our 3D culture system and novel mouse xenograft model.

LncRNA MALAT1 Participates in Protection of High-Molecular-Weight Hyaluronan against Smoke-Induced Acute Lung Injury by Upregulation of SOCS-1

Smoke-induced acute lung injury (ALI) is a grievous disease with high mortality. Despite advances in medical intervention, no drug has yet been approved by the Food and Drug Administration (FDA) for ALI. In this study, we reported that pretreatment with high-molecular-weight hyaluronan (1600 kDa, HA1600) alleviated pulmonary inflammation and injury in mice exposed to smoke and also upregulated long non-coding RNA (lncRNA) metastasis-associated lung adenocarcinoma transcript 1 (MALAT1), as well as suppressor of cytokine signaling-1 (SOCS-1), in the lung tissues. Next, we overexpressed MALAT1 in the lungs by intratracheal administration of adenovirus cloned with MALAT1 cDNA and found that the survival of mice after smoke exposure was improved. Moreover, pulmonary overexpression of MALAT1 ameliorated smoke-induced ALI in mice and elevated the level of SOCS-1 in the lungs. In conclusion, the results pointed out that HA1600 exerted a protective effect against smoke-induced ALI through increasing the MALAT1 level and the subsequent SOCS-1 expression. Our study provides a potential therapeutic approach to smoke-induced ALI and a novel insight into the mechanism of action of HA1600.

Recent advances in pharmacological diversification of Src family kinase inhibitors

Background

Src kinase, a nonreceptor protein-tyrosine kinase is composed of 11 members (in human) and is involved in a wide variety of essential functions required to sustain cellular homeostasis and survival.

Main body of the abstract

Deregulated activity of Src family kinase is related to malignant transformation. In 2001, Food and Drug Administration approved imatinib for the treatment of chronic myeloid leukemia followed by approval of various other inhibitors from this category as effective therapeutics for cancer patients. In the past decade, Src family kinase has been investigated for the treatment of diverse pathologies in addition to cancer. In this regard, we provide a systematic evaluation of Src kinase regarding its mechanistic role in cancer and other diseases. Here we comment on preclinical and clinical success of Src kinase inhibitors in cancer followed by diabetes, hypertension, tuberculosis, and inflammation.

Short conclusion

Studies focusing on the diversified role of Src kinase as potential therapeutical target for the development of medicinally active agents might produce significant advances in the management of not only various types of cancer but also other diseases which are in demand for potent and safe therapeutics.

Inhibition of Src Family Kinases Ameliorates LPS-Induced Acute Kidney Injury and Mitochondrial Dysfunction in Mice

Acute kidney injury (AKI), a critical syndrome characterized by a rapid decrease of kidney function, is a global health problem. Src family kinases (SFK) are proto-oncogenes that regulate diverse biological functions including mitochondrial function. Since mitochondrial dysfunction plays an important role in the development of AKI, and since unbalanced SFK activity causes mitochondrial dysfunction, the present study examined the role of SFK in AKI. Lipopolysaccharides (LPS) inhibited mitochondrial biogenesis and upregulated the expression of NGAL, a marker of tubular epithelial cell injury, in mouse proximal tubular epithelial (mProx) cells. These alterations were prevented by PP2, a pan SFK inhibitor. Importantly, PP2 pretreatment significantly ameliorated LPS-induced loss of kidney function and injury including inflammation and oxidative stress. The attenuation of LPS-induced AKI by PP2 was accompanied by the maintenance of mitochondrial biogenesis. LPS upregulated SFK, especially Fyn and Src, in mouse kidney as well as in mProx cells. These data suggest that Fyn and Src kinases are involved in the pathogenesis of LPS-induced AKI, and that inhibition of Fyn and Src kinases may have a potential therapeutic effect, possibly via improving mitochondrial biogenesis.

Src kinase inhibition with dasatinib impairs neutrophil function and clearance of Escherichia coli infection in a murine model of acute lung injury

BACKGROUND

Neutrophils rapidly respond to and clear infection from tissues, but can also induce tissue damage through excessive degranulation, when acute inflammation proceeds unchecked. A number of key neutrophil functions, including adhesion-dependent degranulation, are controlled by src family kinases. Dasatinib is a potent src inhibitor used in treating patients with chronic myeloid leukaemia and treatment-resistant acute lymphoblastic leukaemia. We hypothesized that dasatinib would attenuate acute inflammation by inhibiting neutrophil recruitment, degranulation and endothelial cell injury, without impairing bacterial clearance, in a murine model of bacteria-induced acute lung injury. C57BL/6 mice received intratracheal Escherichia coli, and were treated with intraperitoneal dasatinib or control. Bacterial clearance, lung injury, and markers of neutrophil recruitment and degranulation were measured. Separately, human blood neutrophils were exposed to dasatinib or control, and the effects on a range of neutrophil functions assessed.

RESULTS

Dasatinib was associated with a dose-dependent significant increase in E. coli in the mouse lung, accompanied by impairment of organ function, reflected in significantly increased protein leak across the alveolar-capillary membrane. However, the number of neutrophils entering the lung was unaffected, suggesting that dasatinib impairs neutrophil function independent of migration. Dasatinib did not cause direct toxicity to human neutrophils, but led to significant reductions in phagocytosis of E. coli, adhesion, chemotaxis, generation of superoxide anion and degranulation of primary and secondary granules. However, no biologically important effect of dasatinib on neutrophil degranulation was observed in mice.

CONCLUSIONS

Contrary to our starting hypothesis, src kinase inhibition with dasatinib had a detrimental effect on bacterial clearance in the mouse lung and therefore does not represent an attractive therapeutic strategy to treat primary infective lung inflammation. Data from human neutrophils suggest that dasatanib has inhibitory effects on a range of neutrophil functions.

Src family kinases and pulmonary fibrosis: A review

Src family kinases (SFKs) is a non-receptor protein tyrosine kinases family. They are crucial in signal transduction and regulation of various cell biological processes, such as proliferation, differentiation and apoptosis. The role and mechanism of SFKs in tumorigenesis have been widely studied. However, more and more studies have also shown that SFKs are involved in the pathogenesis of pulmonary fibrosis (PF). Myofibroblasts activation, epithelial-mesenchymal transition and inflammation response are three pivotal pathomechanisms in the development of pulmonary fibrotic disease. In this article, we summarize the roles of SFKs in these biological processes. SFKs play a crucial role in the pathogenesis of PF, making it a promising molecular target for the treatment of these diseases. We will pay special attention to the role of SFKs in idiopathic pulmonary fibrosis (IPF), and also emphasize the important findings in other pulmonary fibrotic diseases because their pathological mechanisms are similar. We will then describe the translation results obtained with SFKs inhibitors in basic and clinical studies.

LncRNA analysis of lung tissues after hUC-MSCs and FTY720 treatment of lipopolysaccharide-induced acute lung injury in mouse models

Acute lung injury (ALI), a persistent lung inflammatory response syndrome, may evolve into acute respiratory distress syndrome (ARDS). Characterized by rapid onset, critical features, and a complex etiology, ALI remains a challenging critical respiratory disease. Recently, mesenchymal stem cells (MSCs) have provided a new solution for the treatment of ALI. We built a lipopolysaccharide (LPS)-induced ALI model in mice. After treatment with human umbilical cord mesenchymal stem cells (hUC-MSCs), FTY720, or a combination of hUC-MSCs and FTY207, the lung inflammatory response was apparently attenuated. To understand the mechanism underlying MSCs treatment of ALI at the genetic level, significant differentially expressed long non-coding RNAs (lncRNAs) between the treatment and model groups were analyzed using microarray technology. Moreover, genetic gene prediction, gene ontology (GO) analysis, pathway analysis, and transcription factor (TF) prediction were carried out. The results showed that a total of 66 lncRNAs were differentially expressed in all three treatment groups, including 8 up-regulated and 58 down-regulated lncRNAs. LncRNA A_30_P01029806 and A_30_P01029194, which were down-regulated, were involved in the signaling pathways closely related to ALI. Through further TF analysis, we identified several significant TFs which lay a foundation for revealing the mechanism underlying lncRNAs treatment of ALI. LncRNA A_30_P01029806 and A_30_P01029194 may serve as candidate biomarkers in the diagnosis and treatment of ALI.

The Importance of Tyrosine Phosphorylation Control of Cellular Signaling Pathways in Respiratory Disease: pY and pY Not

Reversible phosphorylation of proteins on tyrosine residues is an essential signaling mechanism by which diverse cellular processes are closely regulated. The tight temporal and spatial control of the tyrosine phosphorylation status of proteins by protein tyrosine kinases (PTKs) and protein tyrosine phosphatases (PTPs) is critical to cellular homeostasis as well as to adaptations to the external environment. Via regulation of cellular signaling cascades involving other protein kinases and phosphatases, receptors, adaptor proteins, and transcription factors, PTKs and PTPs closely control diverse cellular processes such as proliferation, differentiation, migration, inflammation, and maintenance of cellular barrier function. Given these key regulatory roles, it is not surprising that dysfunction of PTKs and PTPs is important in the pathogenesis of human disease, including many pulmonary diseases. The roles of various PTKs and PTPs in acute lung injury and repair, pulmonary fibrosis, pulmonary vascular disease, and inflammatory airway disease are discussed in this review. It is important to note that although there is overlap among many of these proteins in various disease states, the mechanisms by which they influence the pathogenesis of these conditions differ, suggesting wide-ranging roles for these enzymes and their potential as therapeutic targets.

The role of Src & ERK1/2 kinases in inspiratory resistive breathing induced acute lung injury and inflammation

Background

Inspiratory resistive breathing (IRB), a hallmark of obstructive airway diseases, is associated with large negative intrathoracic pressures, due to strenuous contractions of the inspiratory muscles. IRB is shown to induce lung injury in previously healthy animals. Src is a multifunctional kinase that is activated in the lung by mechanical stress. ERK1/2 kinase is a downstream target of Src. We hypothesized that Src is activated in the lung during IRB, mediates ERK1/2 activation and IRB-induced lung injury.

Methods

Anaesthetized, tracheostomized adult rats breathed spontaneously through a 2-way non-rebreathing valve. Resistance was added to the inspiratory port to provide a peak tidal inspiratory pressure of 50% of maximum (inspiratory resistive breathing). Activation of Src and ERK1/2 in the lung was estimated during IRB. Following 6 h of IRB, respiratory system mechanics were measured by the forced oscillation technique and bronchoalveolar lavage (BAL) was performed to measure total and differential cell count and total protein levels. IL-1b and MIP-2a protein levels were measured in lung tissue samples. Wet lung weight to total body weight was measured and Evans blue dye extravasation was estimated to measure lung permeability. Lung injury was evaluated by histology. The Src inhibitor, PP-2 or the inhibitor of ERK1/2 activation, PD98059 was administrated 30 min prior to IRB.

Results

Src kinase was activated 30 min after the initiation of IRB. Src inhibition ameliorated the increase in BAL cellularity after 6 h IRB, but not the increase of IL-1β and MIP-2a in the lung. The increase in BAL total protein and lung injury score were not affected. The increase in tissue elasticity was partly inhibited. Src inhibition blocked ERK1/2 activation at 3 but not at 6 h of IRB. ERK1/2 inhibition ameliorated the increase in BAL cellularity after 6 h of IRB, blocked the increase of IL-1β and returned Evans blue extravasation and wet lung weight to control values. BAL total protein and the increase in elasticity were partially affected. ERK1/2 inhibition did not significantly change total lung injury score compared to 6 h IRB.

Conclusions

Src and ERK1/2 are activated in the lung following IRB and participate in IRB-induced lung injury.

Protective effects of SOCS3 overexpression in high glucose‑induced lung epithelial cell injury through the JAK2/STAT3 pathway

Previous studies have suggested that the Janus kinase (JAK)/signal transducers and activators of transcription (STAT) pathway is involved in hyperglycemia-induced lung injury. The present study aimed to investigate the roles of suppressor of cytokine signaling3 (SOCS3) in the regulation of JAK2/STAT3 activation following high glucose (HG) treatment in A549 human pulmonary epithelial cells. Cell viability was evaluated using Cell Counting Kit-8 and lactate dehydrogenase assays. HG-induced inflammatory injury in A549 cells was assessed through the evaluation of interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α) levels using ELISA. The protein expression levels of SOCS3, JAK2, STAT3, phosphorylated (p)-JAK2 and p-STAT3 were determined using western blot analysis. Cellular viability was significantly decreased, whereas IL-6 and TNF-α levels were significantly increased, following HG stimulation of A549 cells. In addition, the protein levels of SOCS3, p-JAK2 and p-STAT3 were significantly increased in HG-treated cells. Treatment with the JAK2/STAT3 inhibitor tyrphostin AG490, or SOCS3 overexpression, appeared to prevent the HG-induced alterations in protein expression. Furthermore, cellular viability was enhanced, whereas the levels of proinflammatory cytokines were suppressed. These finding suggested the involvement of the SOCS3/JAK2/STAT3 signaling pathway in HG-induced responses in lung cells. Therefore, it may be hypothesized that the inhibition of the JAK2/STAT3 pathway through SOCS3 overexpression may prevent hyperglycemia-induced lung injury, and may have therapeutic potential for the treatment of patients with diabetic lung injury.

Protective effect of suppressing STAT3 activity in LPS-induced acute lung injury

Acute lung injury (ALI) and acute respiratory distress syndrome (ARDS) are diseases with high mortality. Macrophages and neutrophils are responsible for inflammatory responses in ALI and ARDS, which are characterized by excessive production of proinflammatory mediators in bronchoalveolar lavage fluid (BALF) and plasma. Aberrant activation of the JAK/STAT pathway is critical for persistent inflammation in many conditions such as infection and autoimmunity. Given the importance of the STAT3 transcription factor in activating macrophages and neutrophils and augmenting inflammation, we investigated the therapeutic potential of inhibiting STAT3 activity using the small-molecule STAT3 inhibitor, LLL12. Our results demonstrate that LPS induces STAT3 activation in macrophages in vitro and in CD45⁺CD11b⁺ cells from BALF in the LPS-induced ALI model in vivo. LLL12 treatment inhibits LPS-induced lung inflammation in the ALI model, which is accompanied by suppression of LPS-induced STAT3 activation and an inhibition of macrophage and inflammatory cell infiltration in lung and BALF. LLL12 treatment also suppresses expression of proinflammatory genes including IL-1β, IL-6, TNF-α, iNOS, CCL2, and MHC class II in macrophages and inflammatory cells from BALF and serum as determined by ELISA. Furthermore, hyperactivation of STAT3 in LysMCre-SOCS3^fl/fl mice accelerates the severity of inflammation in the ALI model. Both pre- and post-LPS treatment with LLL12 decrease LPS-induced inflammatory responses in mice with ALI. Importantly, LLL12 treatment attenuates STAT3 phosphorylation in human peripheral blood mononuclear cells induced by plasma from patients with ARDS, which suggests the feasibility of targeting the STAT3 pathway therapeutically for patients with ALI and ARDS.

Inhibition of EphA2/EphrinA1 signal attenuates lipopolysaccharide-induced lung injury

Eph-Ephrin signalling mediates various cellular processes, including vasculogenesis, angiogenesis, cell migration, axon guidance, fluid homoeostasis and repair after injury. Although previous studies have demonstrated that stimulation of the EphA receptor induces increased vascular permeability and inflammatory response in lung injury, the detailed mechanisms of EphA2 signalling are unknown. In the present study, we evaluated the role of EphA2 signalling in mice with lipopolysaccharide (LPS)-induced lung injury. Acute LPS exposure significantly up-regulated EphA2 and EphrinA1 expression. Compared with LPS+IgG mice (IgG instillation after LPS exposure), LPS+EphA2 mAb mice [EphA2 monoclonal antibody (mAb) instillation posttreatment after LPS exposure] had attenuated lung injury and reduced cell counts and protein concentration of bronchoalveolar lavage fluid (BALF). EphA2 mAb posttreatment down-regulated the expression of phosphoinositide 3-kinases (PI3K) 110γ, phospho-Akt, phospho-NF-κB p65, phospho-Src and phospho-S6K in lung lysates. In addition, inhibiting the EphA2 receptor augmented the expression of E-cadherin, which is involved in cell-cell adhesion. Our study identified EphA2 receptor as an unrecognized modulator of several signalling pathways-including PI3K-Akt-NF-kB, Src-NF-κB, E-cadherin and mTOR-in LPS-induced lung injury. These results suggest that EphA2 receptor inhibitors may function as novel therapeutic agents for LPS-induced lung injury.

Targeting Drug-Sensitive and -Resistant Strains of Mycobacterium tuberculosis by Inhibition of Src Family Kinases Lowers Disease Burden and Pathology

The existing treatment regimen for tuberculosis (TB) suffers from deficiencies like high doses of antibiotics, long treatment duration, and inability to kill persistent populations in an efficient manner. Together, these contribute to the emergence of drug-resistant tuberculosis. Recently, several host factors were identified which help intracellular survival of Mycobacterium tuberculosis within the macrophage. These factors serve as attractive targets for developing alternate therapeutic strategies against M. tuberculosis. This strategy promises to be effective against drug-resistant strains. The approach also has potential to considerably lower the risk of emergence of new drug-resistant strains. We explored tyrosine kinase Src as a host factor exploited by virulent M. tuberculosis for intracellular survival. We show that Src inhibition can effectively control tuberculosis in infected guinea pigs. Moreover, Src inhibition ameliorated TB-associated pathology in guinea pigs. Thus, Src inhibitors have strong potential to be developed as possible anti-TB drugs.

In view of emerging drug resistance among bacterial pathogens, including Mycobacterium tuberculosis, the development of novel therapeutic strategies is increasingly being sought. A recent paradigm in antituberculosis (anti-TB) drug development is to target the host molecules that are crucial for intracellular survival of the pathogen. We previously showed the importance of Src tyrosine kinases in mycobacterial pathogenesis. Here, we report that inhibition of Src significantly reduced survival of H37Rv as well as multidrug-resistant (MDR) and extremely drug-resistant (XDR) strains of M. tuberculosis in THP-1 macrophages. Src inhibition was also effective in controlling M. tuberculosis infection in guinea pigs. In guinea pigs, reduced M. tuberculosis burden due to Src inhibition also led to a marked decline in the disease pathology. In agreement with the theoretical framework of host-directed approaches against the pathogen, Src inhibition was equally effective against an XDR strain in controlling infection in guinea pigs. We propose that Src inhibitors could be developed into effective host-directed anti-TB drugs, which could be indiscriminately used against both drug-sensitive and drug-resistant strains of M. tuberculosis.

IMPORTANCE The existing treatment regimen for tuberculosis (TB) suffers from deficiencies like high doses of antibiotics, long treatment duration, and inability to kill persistent populations in an efficient manner. Together, these contribute to the emergence of drug-resistant tuberculosis. Recently, several host factors were identified which help intracellular survival of Mycobacterium tuberculosis within the macrophage. These factors serve as attractive targets for developing alternate therapeutic strategies against M. tuberculosis. This strategy promises to be effective against drug-resistant strains. The approach also has potential to considerably lower the risk of emergence of new drug-resistant strains. We explored tyrosine kinase Src as a host factor exploited by virulent M. tuberculosis for intracellular survival. We show that Src inhibition can effectively control tuberculosis in infected guinea pigs. Moreover, Src inhibition ameliorated TB-associated pathology in guinea pigs. Thus, Src inhibitors have strong potential to be developed as possible anti-TB drugs.

The Src family tyrosine kinases src and yes have differential effects on inflammation-induced apoptosis in human pulmonary microvascular endothelial cells

Endothelial cells are essential for normal lung function: they sense and respond to circulating factors and hemodynamic alterations. In inflammatory lung diseases such as acute respiratory distress syndrome, endothelial cell apoptosis is an inciting event in pathogenesis and a prominent pathological feature. Endothelial cell apoptosis is mediated by circulating inflammatory factors, which bind to receptors on the cell surface, activating signal transduction pathways, leading to caspase-3-mediated apoptosis. We hypothesized that yes and src have differential effects on caspase-3 activation in human pulmonary microvascular endothelial cells (hPMVEC) due to differential downstream signaling effects. To test this hypothesis, hPMVEC were treated with siRNA against src (siRNAsrc), siRNA against yes (siRNAyes), or their respective scramble controls. After recovery, the hPMVEC were treated with cytomix (LPS, IL-1β, TNF-α, and IFN-γ). Treatment with cytomix induced activation of the extracellular signal-regulated kinase (ERK) pathway and caspase-3-mediated apoptosis. Treatment with siRNAsrc blunted cytomix-induced ERK activation and enhanced cleaved caspase-3 levels, while treatment with siRNAyes enhanced cytomix-induced ERK activation and attenuated levels of cleaved caspase-3. Inhibition of the ERK pathway using U0126 enhanced cytomix-induced caspase-3 activity. Treatment of hPMVEC with cytomix induced Akt activation, which was inhibited by siRNAsrc. Inhibition of the phosphatidylinositol 3-kinase/Akt pathway using LY294002 prevented cytomix-induced ERK activation and augmented cytomix-induced caspase-3 cleavage. Together, our data demonstrate that, in hPMVEC, yes activation blunts the ERK cascade in response to cytomix, resulting in greater apoptosis, while cytomix-induced src activation induces the phosphatidylinositol 3-kinase pathway, which leads to activation of Akt and ERK and attenuation of apoptosis.

Activation of Src-dependent Smad3 signaling mediates the neutrophilic inflammation and oxidative stress in hyperoxia-augmented ventilator-induced lung injury

BACKGROUND

Mechanical ventilation and concomitant administration of hyperoxia in patients with acute respiratory distress syndrome can damage the alveolar epithelial and capillary endothelial barrier by producing inflammatory cytokines and reactive oxygen species. The Src tyrosine kinase and Smad3 are crucial inflammatory regulators used for ventilator-induced lung injury (VILI). The mechanisms regulating interactions between high-tidal-volume mechanical ventilation, hyperoxia, and acute lung injury (ALI) are unclear. We hypothesized that high-tidal-volume mechanical stretches and hyperoxia augment lung inflammation through upregulation of the Src and Smad3 pathways.

METHODS

Wild-type or Src-deficient C57BL/6 mice, aged between 6 and 8 weeks, were exposed to high-tidal-volume (30 mL/kg) ventilation with room air or hyperoxia for 1-4 h after 2-mg/kg Smad3 inhibitor (SIS3) administration. Nonventilated mice were used as control subjects.

RESULTS

We observed that the addition of hyperoxia to high-tidal-volume mechanical ventilation further induced microvascular permeability, neutrophil infiltration, macrophage inflammatory protein-2 and matrix metalloproteinase-9 (MMP-9) production, malondialdehyde, nicotinamide adenine dinucleotide phosphate oxidase activity, MMP-9 mRNA expression, hypoxemia, and Src and Smad3 activation (P < 0.05). Hyperoxia-induced augmentation of VILI was attenuated in Src-deficient mice and mice with pharmacological inhibition of Smad3 activity by SIS3 (P < 0.05). Mechanical ventilation of Src-deficient mice with hyperoxia further reduced the activation of Smad3.

CONCLUSIONS

Our data suggest that hyperoxia-increased high-tidal-volume ventilation-induced ALI partially depends on the Src and Smad3 pathways.

The Src-Family Kinases Hck and Fgr Regulate Early Lipopolysaccharide-Induced Myeloid Cell Recruitment into the Lung and Their Ability To Secrete Chemokines

Myeloid leukocyte recruitment into the lung in response to environmental cues represents a key factor for the induction of lung damage. We report that Hck- and Fgr-deficient mice show a profound impairment in early recruitment of neutrophils and monocytes in response to bacterial LPS. The reduction in interstitial and airway neutrophil recruitment was not due to a cell-intrinsic migratory defect, because Hck- and Fgr-deficient neutrophils were attracted to the airways by the chemokine CXCL2 as wild type cells. However, early accumulation of chemokines and TNF-α in the airways was reduced in hck(-/-)fgr(-/-) mice. Considering that chemokine and TNF-α release into the airways was neutrophil independent, as suggested by a comparison between control and neutrophil-depleted mice, we examined LPS-induced chemokine secretion by neutrophils and macrophages in wild type and mutant cells. Notably, mutant neutrophils displayed a marked deficit in their capability to release the chemokines CXCL1, CXCL2, CCL3, and CCL4 and TNF-α in response to LPS. However, intracellular accumulation of these chemokines and TNF-α, as well as secretion of a wide array of cytokines, including IL-1α, IL-1β, IL-6, and IL-10, by hck(-/-)fgr(-/-) neutrophils was normal. Intriguingly, secretion of CXCL1, CXCL2, CCL2, CCL3, CCL4, RANTES, and TNF-α, but not IL-1α, IL-1β, IL-6, IL-10, and GM-CSF, was also markedly reduced in bone marrow-derived macrophages. Consistently, the Src kinase inhibitors PP2 and dasatinib reduced chemokine secretion by neutrophils and bone marrow-derived macrophages. These findings identify Src kinases as a critical regulator of chemokine secretion in myeloid leukocytes during lung inflammation.

Changes in endothelial connexin 43 expression inversely correlate with microvessel permeability and VE-cadherin expression in endotoxin-challenged lungs

Endothelial barrier restoration reverses microvessel hyperpermeability and facilitates recovery from lung injury. Because inhibiting connexin 43 (Cx43)-dependent interendothelial communication blunts hyperpermeability in single microvessels, we determined whether endothelial Cx43 levels correlate with changes in microvessel permeability during recovery from lung injury. Toward this, bacterial endotoxin was instilled intratracheally into rat lungs, and at different durations postinstillation the lungs were isolated and blood perfused. Microvessel Cx43 expression was quantified by in situ immunofluorescence and microvessel permeability via a fluorescence method. To supplement the immunofluorescence data, protein levels were determined by immunoblots of lung tissue from endotoxin-instilled rats. Immunofluorescence and immunoblot together revealed that both Cx43 expression and microvessel permeability increased above baseline within a few hours after endotoxin instillation but declined progressively over the next few days. On day 5 postendotoxin, microvessel Cx43 declined to negligible levels, resulting in complete absence of intermicrovessel communication determined by photolytic uncaging of Ca(2+). However, by day 14, both Cx43 expression and microvessel permeability returned to baseline levels. In contrast to Cx43, expression of microvessel vascular endothelial (VE)-cadherin, a critical determinant of vascular barrier integrity, exhibited an inverse trend by initially declining below baseline and then returning to baseline at a longer duration. Knockdown of vascular Cx43 by tail vein injection of Cx43 shRNA increased VE-cadherin expression, suggesting that reduction in Cx43 levels may modulate VE-cadherin levels in lung microvessels. Together, the data suggest that endotoxin challenge initiates interrelated changes in microvessel Cx43, VE-cadherin, and microvessel permeability, with changes in Cx43 temporally leading the other responses.

Pretreatment with andrographolide pills(®) attenuates lipopolysaccharide-induced pulmonary microcirculatory disturbance and acute lung injury in rats

OBJECTIVE

The purpose of this study was to explore the protective effect of AP on LPS-induced PMD and ALI.

METHODS

Male SD rats were continuously infused with LPS (5 mg/kg/h) for one hour to induce PMD and ALI. AP was administrated orally one hour before LPS exposure. Arterial blood pressure and HR were monitored. Blood gas analysis, histological observation, cytokines in plasma, leukocyte recruitment, pulmonary oxidative stress, microvessel permeability, edema, and related proteins were evaluated six hours after LPS challenge.

RESULTS

Rats receiving LPS exhibited significant alterations, including hypotension, tachycardia, increase in cytokines, neutrophil adhesion and infiltration, oxidative stress, and microvessel hyperpermeability, resulting in pulmonary injury and dysfunction. AP (0.18 g/kg or 1.8 g/kg) improved rat survival rate, and significantly attenuated all aforementioned insults, and inhibited LPS-induced increase in adhesion molecules, up-regulation of Cav-1 and Src kinase and NADPH oxidase subunits (p47(phox) and p67(phox) ) membrane translocation in lung tissue, and preserved JAM-1 and claudin-5.

CONCLUSIONS

The results demonstrated the protective effect of AP on LPS-induced PMD and ALI, suggesting the potential of AP as a prophylactic strategy for LPS-induced ALI.

Recombinant human brain natriuretic peptide ameliorates trauma-induced acute lung injury via inhibiting JAK/STAT signaling pathway in rats

BACKGROUND

JAK/STAT signal pathway plays an important role in the inflammation process of acute lung injury (ALI). This study aimed to investigate the correlation between recombinant human brain natriuretic peptide (rhBNP) and the JAK/STAT signaling pathway and to explore the protective mechanism of rhBNP against trauma-induced ALI.

METHODS

The arterial partial pressure in oxygen, lung wet-dry weight ratios, protein content in bronchoalveolar lavage fluid, the histopathologic of the lung, as well as the protein expressions of STAT1, JAK2, and STAT3 were detected.

RESULTS

Sprague-Dawley rats were randomly divided into five groups: a control group, a sham-operated group, an ALI group, an ALI + rhBNP group, and an ALI + AG490 group. At 4 hours, 12 hours, 1 day, 3 days, and 7 days after injury, injured lung specimens were harvested. rhBNP pretreatment significantly ameliorated hypoxemia and histopathologic changes and alleviated pulmonary edema in trauma-induced ALI rats. rhBNP pretreatment reduced the phosphorylated protein and total protein level of STAT1. Similarly to JAK-specific inhibitor AG490, rhBNP was shown to significantly inhibit the phosphorylation of JAK2 and STAT3 in rats with trauma-induced ALI.

CONCLUSION

Our experimental findings indicated that rhBNP can protect rats against trauma-induced ALI and that its underlying mechanism may be related to the inhibition of JAK/STAT signaling pathway activation.

STAT3-dependent CXC chemokine formation and neutrophil migration in streptococcal M1 protein-induced acute lung inflammation

Streptococcus pyogenes cause infections ranging from mild pharyngitis to severe streptococcal toxic shock syndrome (STSS). The M1 serotype of Streptococcus pyogenes is most frequently associated with STSS. Herein, it was hypothesized that STAT3 signaling might be involved in M1 protein-evoked lung inflammation. The STAT3 inhibitor, S3I-201, was administered to male C57Bl/6 mice before iv challenge with M1 protein. Bronchoalveolar fluid and lung tissue were harvested for quantification of STAT3 activity, neutrophil recruitment, edema, and CXC chemokine formation. Neutrophil expression of Mac-1 was quantified by use of flow cytometry. Levels of IL-6 and HMGB1 were determined in plasma. CXCL2-induced neutrophil chemotaxis was studied in vitro. Administration of S3I-201 markedly reduced M1 protein-provoked STAT3 activity, neutrophil recruitment, edema formation, and inflammatory changes in the lung. In addition, M1 protein significantly increased Mac-1 expression on neutrophils and CXC chemokine levels in the lung. Treatment with S3I-201 had no effect on M1 protein-induced expression of Mac-1 on neutrophils. In contrast, inhibition of STAT3 activity greatly reduced M1 protein-induced formation of CXC chemokines in the lung. Interestingly, STAT3 inhibition markedly decreased plasma levels of IL-6 and HMGB1 in animals exposed to M1 protein. Moreover, we found that S3I-201 abolished CXCL2-induced neutrophil migration in vitro. In conclusion, these novel findings indicate that STAT3 signaling plays a key role in mediating CXC chemokine production and neutrophil infiltration in M1 protein-induced acute lung inflammation.

Analysis of mechanical ventilation and lipopolysaccharide‑induced acute lung injury using DNA microarray analysis

Gene expression profiles of samples taken from patients with acute lung injury (ALI) induced by mechanical ventilation (MV) and lipopolysaccharide (LPS) were analyzed in order to identify key genes, and explore the underlying mechanisms. The GSE2411 microarray data set was downloaded from the Gene Expression Omnibus. This data set contained microarray data from 24 mouse lung samples, which were equally divided into four groups: Control group, MV group, LPS group and MV+LPS group. Differentially expressed genes (DEGs) were identified in the MV, LPS and MV+LPS groups, as compared with the control group, using packages of R software. Hierarchical clustering and between‑group comparisons were performed for each group of DEGs. Overrepresented biological processes were revealed by functional enrichment analysis using the Database for Annotation, Visualization and Integrated Discovery. Unique DEGs in the LPS and MV+LPS groups were selected, and pathway enrichment analyses were performed using the Kyoto Encyclopedia of Genes and Genomes Orthology Based Annotation system. A total of 32, 264 and 685 DEGs were identified in the MV, LPS and MV+LPS groups, respectively. The MV+LPS group had more DEGs, as compared with the other two treatment groups. Genes associated with the immune and inflammatory responses were significantly overrepresented in both the LPS and MV+LPS groups, suggesting that LPS dominated the progression of ALI. Unique DEGs in the LPS and MV+LPS groups were associated with cytokine‑cytokine receptor interaction. The Janus kinase‑signal transducer and activator of transcription signaling pathway was shown to be enriched in the LPS+MV‑unique DEGs. The results of the present study demonstrated that MV could exaggerate the transcriptional response of the lungs to LPS. Numerous key genes were identified, which may advance knowledge regarding the pathogenesis of ALI.

Matrix metalloproteinases and protein tyrosine kinases: potential novel targets in acute lung injury and ARDS

Acute lung injury (ALI) and ARDS fall within a spectrum of pulmonary disease that is characterized by hypoxemia, noncardiogenic pulmonary edema, and dysregulated and excessive inflammation. While mortality rates have improved with the advent of specialized ICUs and lung protective mechanical ventilation strategies, few other therapies have proven effective in the management of ARDS, which remains a significant clinical problem. Further development of biomarkers of disease severity, response to therapy, and prognosis is urgently needed. Several novel pathways have been identified and studied with respect to the pathogenesis of ALI and ARDS that show promise in bridging some of these gaps. This review will focus on the roles of matrix metalloproteinases and protein tyrosine kinases in the pathobiology of ALI in humans, and in animal models and in vitro studies. These molecules can act independently, as well as coordinately, in a feed-forward manner via activation of tyrosine kinase-regulated pathways that are pivotal in the development of ARDS. Specific signaling events involving proteolytic processing by matrix metalloproteinases that contribute to ALI, including cytokine and chemokine activation and release, neutrophil recruitment, transmigration and activation, and disruption of the intact alveolar-capillary barrier, will be explored in the context of these novel molecular pathways.

Mechanical ventilation augments bleomycin-induced epithelial-mesenchymal transition through the Src pathway

Mechanical ventilation used in patients with acute respiratory distress syndrome (ARDS) can damage pulmonary epithelial cells by producing inflammatory cytokines and depositing excess collagen. Src participates in plasminogen activator inhibitor-1 (PAI-1) and transforming growth factor-β1(TGF-β1) production during the fibroproliferative phase of ARDS, which involves a process of epithelial-mesenchymal transition (EMT). The mechanisms regulating interactions between mechanical ventilation and EMT are unclear. We hypothesized that EMT induced by high-tidal volume (VT) mechanical stretch-augmented lung inflammation occurs through upregulation of the Src pathway. Five days after administering bleomycin to simulate acute lung injury (ALI), male C57BL/6 mice, either wild-type or Src-deficient, aged 3 months, weighing between 25 and 30 g, were exposed to low-VT (6 ml/kg) or high-VT (30 ml/kg) mechanical ventilation with room air for 1-5 h. Nonventilated mice were used as control subjects. We observed that high-VT mechanical ventilation increased microvascular permeability, PAI-1 and TGF-β1 protein levels, Masson's trichrome staining, extracellular collagen levels, collagen gene expression, fibroblast accumulation, positive staining of α-smooth muscle actin and type I collagen, activation of Src signaling and epithelial apoptotic cell death in wild-type mice (P<0.05). Decreased staining of the epithelial marker, Zonula occludents-1, was also observed. Mechanical stretch-augmented EMT and epithelial apoptosis were attenuated in Src-deficient mice and pharmacological inhibition of Src activity by PP2 (P<0.05). Our data suggest that high-VT mechanical ventilation-augmented EMT after bleomycin-induced ALI partially depends on the Src pathway.

Ginsenoside Rb1 ameliorates lipopolysaccharide-induced albumin leakage from rat mesenteric venules by intervening in both trans- and paracellular pathway

Lipopolysaccharide (LPS) is one of the common pathogens that causes mesentery hyperpermeability- and intestinal edema-related diseases. This study evaluated whether ginsenoside Rb1 (Rb1), an ingredient of a Chinese medicine Panax ginseng, has beneficial effects on mesentery microvascular hyperpermeability induced by LPS and the underlying mechanisms. Male Wistar rats were continuously infused with LPS (5 mg · kg(-1) · h(-1)) via the left jugular vein for 90 min. In some rats, Rb1 (5 mg · kg(-1) · h(-1)) was administrated through the left jugular vein 30 min after LPS infusion. The dynamics of fluorescein isothiocynate-labeled albumin leakage from mesentery venules was assessed by intravital microscopy. Intestinal tissue edema was evaluated by hematoxylin and eosin staining. The number of caveolae in endothelial cells of microvessels was examined by electron microscopy. Confocal microscopy and Western blotting were applied to detect caveolin-1 (Cav-1) expression and phosphorylation, junction-related proteins, and concerning signaling proteins in intestinal tissues and human umbilical vein endothelial cells. LPS infusion evoked an increased albumin leakage from mesentery venules that was significantly ameliorated by Rb1 posttreatment. Mortality and intestinal edema around microvessels were also reduced by Rb1. Rb1 decreased caveolae number in endothelial cells of microvessels. Cav-1 expression and phosphorylation, VE-Cadherin phosphorylation, ZO-1 degradation, nuclear factor-κB (NF-κB) activation, and Src kinase phosphorylation were inhibited by Rb1. Rb1 ameliorated microvascular hyperpermeability after the onset of endotoxemia and improved intestinal edema through inhibiting caveolae formation and junction disruption, which was correlated to suppression of NF-κB and Src activation.

Barrier enhancing signals in pulmonary edema

Increased endothelial permeability and reduction of alveolar liquid clearance capacity are two leading pathogenic mechanisms of pulmonary edema, which is a major complication of acute lung injury, severe pneumonia, and acute respiratory distress syndrome, the pathologies characterized by unacceptably high rates of morbidity and mortality. Besides the success in protective ventilation strategies, no efficient pharmacological approaches exist to treat this devastating condition. Understanding of fundamental mechanisms involved in regulation of endothelial permeability is essential for development of barrier protective therapeutic strategies. Ongoing studies characterized specific barrier protective mechanisms and identified intracellular targets directly involved in regulation of endothelial permeability. Growing evidence suggests that, although each protective agonist triggers a unique pattern of signaling pathways, selected common mechanisms contributing to endothelial barrier protection may be shared by different barrier protective agents. Therefore, understanding of basic barrier protective mechanisms in pulmonary endothelium is essential for selection of optimal treatment of pulmonary edema of different etiology. This article focuses on mechanisms of lung vascular permeability, reviews major intracellular signaling cascades involved in endothelial monolayer barrier preservation and summarizes a current knowledge regarding recently identified compounds which either reduce pulmonary endothelial barrier disruption and hyperpermeability, or reverse preexisting lung vascular barrier compromise induced by pathologic insults.

A critical role for Lyn kinase in strengthening endothelial integrity and barrier function

The Src family kinases (SFKs) c-Src and Yes mediate vascular leakage in response to various stimuli including lipopolysaccharide (LPS) and vascular endothelial growth factor (VEGF). Here, we define an opposing function of another SFK, Lyn, which in contrast to other SFKs, strengthens endothelial junctions and thereby restrains the increase in vascular permeability. Mice lacking Lyn displayed increased mortality in LPS-induced endotoxemia and increased vascular permeability in response to LPS or VEGF challenge compared with wild-type littermates. Lyn knockout mice repopulated with wild-type bone marrow-derived cells have higher vascular permeability than wild-type mice, suggesting a role of endothelial Lyn in the maintenance of the vascular barrier. Small interfering RNA-mediated down-regulation of Lyn disrupted endothelial barrier integrity, whereas expression of a constitutively active mutant of Lyn enhanced the barrier. However, down-regulation of Lyn did not affect LPS-induced endothelial permeability. We demonstrate that Lyn association with focal adhesion kinase (FAK) and phosphorylation of FAK at tyrosine residues 576/577 and 925 were required for Lyn-dependent stabilization of endothelial adherens junctions. Thus, in contrast to c-Src and Yes, which increase vascular permeability in response to stimuli, Lyn stabilizes endothelial junctions through phosphorylation of FAK. Therefore, therapeutics activating Lyn kinase may strengthen the endothelial barrier junction and hence have anti-inflammatory potential.

Tripeptide feG prevents and ameliorates acute pancreatitis-associated acute lung injury in a rodent model

BACKGROUND

The synthetic tripeptide feG (D-Phe-D-Glu-Gly) is a novel pharmacologic agent that decreases neutrophil recruitment, infiltration, and activation in various animal models of inflammatory disease. We aimed to investigate the effect of feG as both a preventive treatment when administered before acute lung injury and as a therapeutic treatment administered following initiation of acute lung injury.

METHODS

Lung injury was assessed following prophylactic or therapeutic intratracheal feG administration in a “two-hit” rodent model of acute pancreatitis plus intratracheal lipopolysaccharide.

RESULTS

Following both prophylactic and therapeutic feG administration, there were significant improvements in arterial blood oxygenation and respiratory mechanics and decreased lung edema, BAL protein concentration, histologic tissue injury scores, BAL cell infiltration, and lung myeloperoxidase activity. Most indices of lung damage were reduced to baseline control values.

CONCLUSIONS

feG reduced leukocyte infiltration, ameliorated the severity of inflammatory damage, and restored lung function when administered either prophylactically or therapeutically in a two-hit rat model of acute pancreatitis plus intratracheal lipopolysaccharide.

Construction of network for protein kinases that play a role in acute pancreatitis

OBJECTIVES

This study aimed to search for protein kinases that play a role in acute pancreatitis and analyze their potential connection with each other.

METHODS

Information of human protein kinases were collected in protein kinase database, and then a systematic search was performed using PubMed for studies addressing the association between these kinases and acute pancreatitis. Gene Ontology Annotations were used to build interactions network for acute pancreatitis-associated protein kinases.

RESULTS

A total of 570 human protein kinases were found, in which 28 kinases play a role in acute pancreatitis. Among the 28 kinases, RIPK1, JAK2, SRC, EGFR, FYN, MET, JAK1, TYK2, and MTOR were annotated in Gene Ontology database. A gene ontology interactions network was built to visualize the common biological process these kinases participated in.

CONCLUSIONS

This study provides observations that protein kinases participate in all the sequential events in the exocrine pancreas in acute pancreatitis and that protein kinases are potential therapeutical target for acute pancreatitis.

LPS induces pp60c-src-mediated tyrosine phosphorylation of Hsp90 in lung vascular endothelial cells and mouse lung

Heat shock protein 90 (Hsp90) inhibitors were initially developed as anticancer agents; however, it is becoming increasing clear that they also possess potent anti-inflammatory properties. Posttranslational modifications of Hsp90 have been reported in tumors and have been hypothesized to affect client protein- and inhibitor-binding activities. In the present study we investigated the posttranslational modification of Hsp90 in inflammation. LPS, a prototypical inflammatory agent, induced concentration- and time-dependent tyrosine (Y) phosphorylation of Hsp90α and Hsp90β in bovine pulmonary arterial and human lung microvascular endothelial cells (HLMVEC). Mass spectrometry identified Y309 as a major site of Y phosphorylation on Hsp90α (Y300 of Hsp90β). LPS-induced Hsp90 phosphorylation was prevented by the Hsp90 inhibitor 17-allyl-amino-demethoxy-geldanamycin (17-AAG) in vitro as well as in lungs from LPS-treated mice, in vivo. Furthermore, 17-AAG prevented LPS-induced pp60src activation. LPS-induced Hsp90 phosphorylation was also prevented by the pp60src inhibitor PP2. Additionally, Hsp90 phosphorylation was induced by infecting cells with a constitutively active pp60src adenovirus, whereas either a dominant-negative pp60src adenovirus or reduced expression of pp60src by a specific siRNA prevented the LPS-induced Y phosphorylation of Hsp90. Transfection of HLMVEC with the nonphosphorylatable Hsp90β Y300F mutant prevented LPS-induced Hsp90β tyrosine phosphorylation but not pp60src activation. Furthermore, the Hsp90β Y300F mutant showed a reduced ability to bind the Hsp90 client proteins eNOS and pp60src and HLMVEC transfected with the mutant exhibited reduced LPS-induced barrier dysfunction. We conclude that inflammatory stimuli cause posttranslational modifications of Hsp90 that are Hsp90-inhibitor sensitive and may be important to the proinflammatory actions of Hsp90.

Inflammatory signalings involved in airway and pulmonary diseases

In respiratory diseases, there is an increased expression of multiple inflammatory proteins in the respiratory tract, including cytokines, chemokines, and adhesion molecules. Chemokines have been shown to regulate inflammation and immune cell differentiation. Moreover, many of the known inflammatory target proteins, such as matrix metalloproteinase-9 (MMP-9), intercellular adhesion molecule-1 (ICAM-1), vascular cell adhesion molecule-1 (VCAM-1), cyclooxygenase-2 (COX-2), and cytosolic phospholipase A₂ (cPLA₂), are associated with airway and lung inflammation in response to various stimuli. Injuriously environmental stimuli can access the lung through either the airways or the pulmonary and systemic circulations. The time course and intensity of responses by resident and circulating cells may be regulated by various inflammatory signalings, including Src family kinases (SFKs), protein kinase C (PKC), growth factor tyrosine kinase receptors, nicotinamide adenine dinucleotide phosphate (NADPH)/reactive oxygen species (ROS), PI3K/Akt, MAPKs, nuclear factor-kappa B (NF-κB), activator protein-1 (AP-1), and other signaling molecules. These signaling molecules regulate both key inflammatory signaling transduction pathways and target proteins involved in airway and lung inflammation. Here, we discuss the mechanisms involved in the expression of inflammatory target proteins associated with the respiratory diseases. Knowledge of the mechanisms of inflammation regulation could lead to the pharmacological manipulation of anti-inflammatory drugs in the respiratory diseases.

Prooxidant-induced c-Src/nuclear factor kappa B-coupled signalling in sensory ganglia mediates cutaneous hyperalgesia

BACKGROUND

Persistent pain resulting from peripheral injury/inflammation is associated with altered sensitivity to cutaneous stimuli, which can manifest as hyperalgesia. The role of oxidant stress in the development, progression and maintenance of hyperalgesia is still not understood. Furthermore, there appears to be a relationship between c-Src kinase in the pain pathway and oxidative stress.

METHODS

We have used a novel prooxidant inflammatory pain model that involves potassium peroxychromate (PPC), a unique prooxidant that produces the same reactants as activated phagocytes. This model was used to investigate the role of oxidant-activated c-Src in mediating hyperalgesia. We compared the effects of PP2 (a Src family kinase inhibitor) and c-Src siRNA on behavioural hyperalgesia with sodium stibogluconate (SSG) (a non-receptor tyrosine phosphatase inhibitor) and AG 1478 (a receptor tyrosine kinase inhibitor).

RESULTS

PP2 and c-Src siRNA attenuated PPC-induced thermal hyperalgesia, while SSG enhanced it. AG 1478 had no effect. PP2 decreased the levels of IL-1β, c-Src/inhibitory kappa B kinase complex formed and prostaglandin E2 produced in the dorsal root ganglia (DRG) ipsilateral to the inflamed paw, while SSG increased the levels of these parameters. c-Src siRNA decreased Src expression and activity in the DRG ipsilateral to the inflamed paw.

CONCLUSIONS

These results confirm that prooxidant-activated c-Src plays a role in initiating and maintaining hyperalgesia by regulating a stimulus-response coupling between the inflamed tissue and the DRG in the pain pathway. Our data also suggest that oxidant-induced dysregulation of c-Src/nuclear factor kappa B coupling may contribute to our understanding of the transition from acute to chronic dysfunctional pain state seen in many human diseases.

Src tyrosine kinase inhibition prevents pulmonary ischemia-reperfusion-induced acute lung injury

PURPOSE

Pulmonary ischemia-reperfusion is a pathological process seen in several clinical conditions, including lung transplantation, cardiopulmonary bypass, resuscitation for circulatory arrest, atherosclerosis, and pulmonary embolism. A better understanding of its molecular mechanisms is very important.

METHODS

Rat left lung underwent in situ ischemia for 60 min, followed by 2 h of reperfusion. The gene expression profiles and Src protein tyrosine kinase (PTK) phosphorylation were studied over time, and PP2, an Src PTK inhibitor, was intravenously administered 10 min before lung ischemia to determine the role of Src PTK in lung injury.

RESULTS

Reperfusion following ischemia significantly changed the expression of 169 genes, with Mmp8, Mmp9, S100a9, and S100a8 being the most upregulated genes. Ischemia alone only affected expression of 9 genes in the lung. However, Src PTK phosphorylation (activation) was increased in the ischemic lung, mainly on the alveolar wall. Src PTK inhibitor pretreatment decreased phosphorylation of Src PTKs, total protein tyrosine phosphorylation, and STAT3 phosphorylation. It increased phosphorylation of the p85α subunit of PI3 kinase, a signal pathway that can inhibit coagulation and inflammation. PP2 reduced leukocyte infiltration in the lung, apoptotic cell death, fibrin deposition, and severity of acute lung injury after reperfusion. Src inhibition also significantly reduced CXCL1 (GRO/KI) and CCL2 (MCP-1) chemokine levels in the serum.

CONCLUSION

During pulmonary ischemia, Src PTK activation, rather than alteration in gene expression, may play a critical role in reperfusion-induced lung injury. Src PTK inhibition presents a new prophylactic treatment for pulmonary ischemia-reperfusion-induced acute lung injury.

Control of NOD2 and Rip2-dependent innate immune activation by GEF-H1

BACKGROUND

Genetic variants of nucleotide-binding oligomerization domain 2 (NOD2) lead to aberrant microbial recognition and can cause chronic inflammatory diseases in patients with Crohn's disease (CD).

METHODS

We utilized gene-specific siRNA mediated knockdown and expression of guanine nucleotide exchange factor H1 (GEF-H1) in wildtype, Rip2-, and Nod2-deficient macrophages, HCT-116 and HEK 293 cells to determine the role of GEF-H1 in NOD2 and Rip2-mediated NF-κB-dependent induction of proinflammatory cytokine expression. Confocal microscopy was used to determine subcellular distribution of GEF-H1, Rip2, and NOD2.

RESULTS

We identified GEF-H1 as an unexpected component of innate immune regulation during microbial pattern recognition by NOD2. Surprisingly, GEF-H1-mediated the activation of Rip2 during signaling by NOD2, but not in the presence of the 3020 insC variant of NOD2 associated with CD. GEF-H1 functioned downstream of NOD2 as part of Rip2-containing signaling complexes and was responsible for phosphorylation of Rip2 by Src tyrosine kinase. Rip2 variants lacking the tyrosine target of GEF-H1-mediated phosphorylation were unable to mediate NF-κB activation in Rip2-deficient macrophages and failed to transduce NOD2 signaling. GEF-H1 is required downstream of NOD2 as part of Rip2-containing signaling complexes for the activation of innate immune responses.

CONCLUSIONS

GEF-H1 connects tyrosine kinase function to NOD-like receptor signaling and is fundamental to the regulation of microbial recognition by ubiquitous innate immune mechanisms mediated by Rip2 kinase.

Inhibiting Mer receptor tyrosine kinase suppresses STAT1, SOCS1/3, and NF-κB activation and enhances inflammatory responses in lipopolysaccharide-induced acute lung injury

Mer signaling participates in a novel inhibitory pathway in TLR activation. The purpose of the present study was to examine the role of Mer signaling in the down-regulation of TLR4 activation-driven immune responses in mice, i.t.-treated with LPS, using the specific Mer-blocking antibody. At 4 h and 24 h after LPS treatment, expression of Mer protein in alveolar macrophages and lung tissue decreased, sMer in BALF increased significantly, and Mer activation increased. Pretreatment with anti-Mer antibody did not influence the protein levels of Mer and sMer levels. Anti-Mer antibody significantly reduced LPS-induced Mer activation, phosphorylation of Akt and FAK, STAT1 activation, and expression of SOCS1 and -3. Anti-Mer antibody enhanced LPS-induced inflammatory responses, including activation of the NF-κB pathway; the production of TNF-α, IL-1β, and MIP-2 and MMP-9 activity; and accumulation of inflammatory cells and the total protein levels in BALF. These results indicate that Mer plays as an intrinsic feedback inhibitor of the TLR4- and inflammatory mediator-driven immune responses during acute lung injury.

Evaluation of lung injury and respiratory mechanics in a rat model of acute pancreatitis complicated with endotoxin

BACKGROUND

Acute lung injury (ALI) is a common complication of acute pancreatitis (AP) and contributes to the majority of AP-associated deaths, particularly in the setting of secondary infection. This 'two-hit' model mimics clinical cases where the presentation of AP is associated with mild lung injury that, following a secondary direct lung infection, can result in respiratory dysfunction and death. We therefore aimed to characterize lung injury in a clinically-relevant 'two-hit' rat model of caerulein-induced AP combined with intratracheal endotoxin.

METHODS

Rats received 7 hourly intraperitoneal injections of caerulein (50 μg/kg). Twenty four hours following the first caerulein injection, rats were anaesthetised and LPS (15 mg/kg) was instilled intratracheally. Following LPS instillation, rats were ventilated for a total of 2 h.

RESULTS

In the present study, AP results in mild pulmonary injury indicated by increased lung myeloperoxidase (MPO) activity and edema, but with no alteration of respiratory function, while intratracheal instillation of LPS results in more substantial pulmonary injury. The induction of AP challenged with secondary intratracheal LPS results in an exacerbation of lung damage indicated by further increased lung edema, plasma and bronchoalveolar (BAL) CINC-1 concentration, lung damage histology score, and lung tissue resistance and elastance, compared with LPS alone.

CONCLUSIONS

In conclusion, the addition of instilled LPS acted as a "second-hit" and exacerbated caerulein-induced AP, compared with the induction of AP alone or the instillation of LPS alone. Given its clinical relevance, this model could prove useful for examination of therapeutic interventions for ALI following secondary infection.

An essential role for Stat3 in regulating IgG immune complex-induced pulmonary inflammation

Growing evidence suggests that transcription factor signal transducer and activator of transcription (Stat) 3 may play an important regulatory role during inflammation. However, the function of Stat3 in acute lung injury (ALI) is largely unknown. In the current study, by using an adenoviral vector expressing a dominant-negative Stat3 isoform (Ad-Stat3-EVA), we determined the role of Stat3 in IgG immune complex (IC)-induced inflammatory responses and injury in the lung from C57BL/6J mice. We show that IgG IC-induced DNA binding activity of Stat3 in the lung was significantly inhibited by Stat3-EVA. We demonstrate that both lung vascular permeability (albumin leak) and lung myeloperoxidase accumulation in the Ad-Stat-EVA treated mice were substantially reduced when compared with values in mice receiving control virus (Ad-GFP) during the injury. Furthermore, intratracheal administration of Ad-Stat3-EVA caused significant decreases in the contents of neutrophils, inflammatory cytokines (TNF-α and IL-6), chemokines [keratinocyte cell-derived chemokine, macrophage inflammatory protein (MIP)-1α, and MIP-1β], and complement component C5a in bronchoalveolar lavage fluids. Using Stat3-specific small interfering RNA, we show that knocking down Stat3 expression in alveolar macrophages (MH-S cells) significantly reduced the production of proinflammatory mediators on IgG IC stimulation. These data suggest that Stat3 plays an essential role in the pathogenesis of IgG IC-induced ALI by mediating the acute inflammatory responses in the lung and alveolar macrophages.

Antenatal inflammation reduces expression of caveolin-1 and influences multiple signaling pathways in preterm fetal lungs

Bronchopulmonary dysplasia (BPD), associated with chorioamnionitis, results from the simultaneous effects of disrupted lung development, lung injury, and repair superimposed on the developing lung. Caveolins (Cavs) are implicated as major modulators of lung injury and remodeling by multiple signaling pathways, although Cavs have been minimally studied in the injured developing lung. We hypothesized that chorioamnionitis-associated antenatal lung inflammation would decrease the expression of Cav-1 in preterm fetal lungs. We tested whether changes occurred in the transcription factors Smad2/3, Smad1/5, Stat3, and Stat1, and we also studied the activation of acid-sphingomyelinase (a-SMase) with the generation of ceramide, along with changes in the expression of heme oxygenase-1 (HO-1) as indicators of possible Cav-1-mediated effects. Fetal sheep were exposed to 10 mg of intra-amniotic endotoxin or saline for 2, 7, or 2 + 7 days before preterm delivery at 124 days of gestation. The expression of Cav-1 and HO-1 and the phosphorylation of Smad and Stat were evaluated by real-time PCR, Western blotting, and/or immunohistochemistry. The activity of a-SMase and the concentrations of ceramide were measured. Intra-amniotic endotoxin decreased Cav-1 mRNA and protein expression in the lungs, with a maximum reduction of Cav-1 mRNA to 50% ± 7% of the control value (P < 0.05), and of Cav-1 protein expression to 20% ± 5% of the control value (P < 0.05). Decreased concentrations of Cav-1 were associated with the elevated phosphorylation of Smad2/3, Stat3, and Stat1, but not of Smad1/5. The expression of HO-1, a-SMase activity, and ceramide increased. Antenatal inflammation decreased the expression of Cav-1 in the preterm fetal lung. The decreased expression of Cav-1 was associated with the activation of the Smad2/3, Stat, and a-SMase/ceramide pathways, and with the increased expression of HO-1. The decreased concentrations of Cav-1 and changes in other signaling pathways may contribute to BPD.

Activation of Src mediates PDGF-induced Smad1 phosphorylation and contributes to the progression of glomerulosclerosis in glomerulonephritis

Platelet-derived growth factor (PDGF) plays critical roles in mesangial cell (MC) proliferation in mesangial proliferative glomerulonephritis. We showed previously that Smad1 contributes to PDGF-dependent proliferation of MCs, but the mechanism by which Smad1 is activated by PDGF is not precisely known. Here we examined the role of c-Src tyrosine kinase in the proliferative change of MCs. Experimental mesangial proliferative glomerulonephritis (Thy1 GN) was induced by a single intravenous injection of anti-rat Thy-1.1 monoclonal antibody. In Thy1 GN, MC proliferation and type IV collagen (Col4) expression peaked on day 6. Immunohistochemical staining for the expression of phospho-Src (pSrc), phospho-Smad1 (pSmad1), Col4, and smooth muscle α-actin (SMA) revealed that the activation of c-Src and Smad1 signals in glomeruli peaked on day 6, consistent with the peak of mesangial proliferation. When treated with PP2, a Src inhibitor, both mesangial proliferation and sclerosis were significantly reduced. PP2 administration also significantly reduced pSmad1, Col4, and SMA expression. PDGF induced Col4 synthesis in association with increased expression of pSrc and pSmad1 in cultured MCs. In addition, PP2 reduced Col4 synthesis along with decreased pSrc and pSmad1 protein expression in vitro. Moreover, the addition of siRNA against c-Src significantly reduced the phosphorylation of Smad1 and the overproduction of Col4. These results provide new evidence that the activation of Src/Smad1 signaling pathway plays a key role in the development of glomerulosclerosis in experimental glomerulonephritis.

The potential of nanoscale combinations of self-assembling peptides and amino acids of the Src tyrosine kinase inhibitor in acute lung injury therapy

Many newly discovered therapeutic agents require a delivery platform in order to translate them into clinical applications. For this purpose, a nanoscale formulation strategy was developed for the Src tyrosine kinase inhibitor PP2. The formulation utilizes the combination of the self-assembling peptides (EAK16-II) and amino acids to minimize the use of the toxic organic solvent DMSO; hence, the biocompatibility of the PP2 nanoformulations was significantly improved. They were found to be non-hemolytic and safe for intravenous and intratracheal administration; the formulations did not alter PP2 activity in Src inhibition on cultured cells. The PP2 nanoformulation was further evaluated on a lipopolysaccharide (LPS)-induced acute lung injury mouse model. Results revealed that the pretreatment of PP2 nanoformulation could decrease the inflammatory cell infiltration and the pro-inflammatory cytokine TNF-α production in the bronchoalveolar lavage fluid after LPS stimulation. The promising therapeutic efficacy and the formulation strategy developed in this work may help further translate PP2 and other hydrophobic therapeutic agents into clinical applications.

Invasion of eukaryotic cells by Borrelia burgdorferi requires β(1) integrins and Src kinase activity

Lyme disease, caused by the bacterium Borrelia burgdorferi, is the most widespread tick-borne infection in the northern hemisphere that results in a multistage disorder with concomitant pathology, including arthritis. During late-stage experimental infection in mice, B. burgdorferi evades the adaptive immune response despite the presence of borrelia-specific bactericidal antibodies. In this study we asked whether B. burgdorferi could invade fibroblasts or endothelial cells as a mechanism to model the avoidance from humorally based clearance. A variation of the gentamicin protection assay, coupled with the detection of borrelial transcripts following gentamicin treatment, indicated that a portion of B. burgdorferi cells were protected in the short term from antibiotic killing due to their ability to invade cultured mammalian cells. Long-term coculture of B. burgdorferi with primary human fibroblasts provided additional support for intracellular protection. Furthermore, decreased invasion of B. burgdorferi in murine fibroblasts that do not synthesize the β(1) integrin subunit was observed, indicating that β(1)-containing integrins are required for optimal borrelial invasion. However, β(1)-dependent invasion did not require either the α(5)β(1) integrin or the borrelial fibronectin-binding protein BBK32. The internalization of B. burgdorferi was inhibited by cytochalasin D and PP2, suggesting that B. burgdorferi invasion required the reorganization of actin filaments and Src family kinases (SFK), respectively. Taken together, these results suggest that B. burgdorferi can invade and retain viability in nonphagocytic cells in a process that may, in part, help to explain the phenotype observed in untreated experimental infection.

L-Arginine-induced acute pancreatitis results in mild lung inflammation without altered respiratory mechanics

Acute lung injury is a common complication of acute pancreatitis (AP) and contributes to the majority of AP-associated deaths. Although some aspects of AP-induced lung inflammation have been demonstrated, investigation of resultant changes in lung function is limited. The aim of this study was to characterize acute lung injury in L-arginine-induced AP. Seven groups of male Sprague-Dawley rats (n = 4-10/group) received 2 intraperitoneal (i.p.) injections of L-arginine (250 mg/100 g) at 6, 12, 24, 36, 48, or 72 hours before measurement of lung impedance mechanics. Control rats (n = 10) received i.p. saline. Bronchoalveolar lavage (BAL), plasma, and pancreatic and lung tissue were collected to determine pancreatic and lung measures of acute inflammation. AP developed between 6 and 36 hours, as indicated by increased pancreatic abnormal acinar cells, myeloperoxidase (MPO) activity, edema, and plasma amylase activity, before beginning to resolve by 72 hours. In the lung, MPO activity increased (2.4-fold) from 12 hours, followed by a modest increase in lung edema at 48 hours, with increased BAL cell count (2.5-fold) up to 72 hours (P < .05). In contrast, no significant changes in lung mechanics were evident over the same period. Despite measurable lung inflammation, no significant deterioration in respiratory function resulted from L-arginine-induced AP.

Caerulein-induced acute pancreatitis results in mild lung inflammation and altered respiratory mechanics

Acute lung injury is a common complication of acute pancreatitis (AP) and contributes to the majority of AP-associated deaths. Although some aspects of AP-induced lung inflammation have been demonstrated, investigation of resultant changes in lung function is limited. The aim of this study was to characterize lung injury in caerulein-induced AP. Male Sprague Dawley rats (n = 7-8/group) received 7 injections of caerulein (50 μg/kg) at 12, 24, 48, 72, 96, or 120 hours before measurement of lung impedance mechanics. Bronchoalveolar lavage (BAL), plasma, pancreatic, and lung tissue were collected to determine pancreatic and lung measures of acute inflammation. AP developed between 12 and 24 hours, as indicated by increased plasma amylase activity and pancreatic myeloperoxidase (MPO) activity, edema, and abnormal acinar cells, before beginning to resolve by 48 hours. In the lung, MPO activity peaked at 12 and 96 hours, with BAL cytokine concentrations peaking at 12 hours, followed by lung edema at 24 hours, and BAL cell count at 48 hours. Importantly, no significant changes in BAL protein concentration or arterial blood gas-pH levels were evident over the same period, and only modest changes were observed in respiratory mechanics. Caerulein-induced AP results in minor lung injury, which is not sufficient to allow protein permeability and substantially alter respiratory mechanics.