Absence Of Neutrophil Elastase Research Articles

Pro-Tumorigenic Role of Neutrophil Elastase in Lymphangioleiomyomatosis (LAM)

Abstract Lymphangioleiomyomatosis (LAM) is an estrogen-sensitive lung disease found almost exclusively in women. LAM is characterized by the hyperproliferation of smooth muscle cells creating small tumors throughout the lungs, resulting in the formation of large cysts that replace normal alveolar space. Growth of these tumors and progression of the cyst development leads to loss of pulmonary function, and sometimes subsequent lung transplantation. LAM tumor cells contain mutations in one of the tuberous sclerosis genes (TSC1 or TSC2), leading to activation of the mTORC1 pathway. In fact, mTOR inhibitors are commonly used to treat LAM; however, these drugs are not always effective and have significant side effects, suggesting the need for new therapeutic targets. Additionally, tumors recur even after lung transplantation and LAM cells are found in circulating body fluids, suggesting a metastatic nature of LAM, and a question of the origin of the LAM cell. Due to LAM’s estrogen sensitivity, female specificity, and metastatic nature, we previously proposed that LAM cells originate from the uterine myometrium. We therefore designed a uterine-specific TSC2-null mouse model where all the mice generate uterine tumors characteristic of LAM and half develop lung metastases. Using RNASeq analysis of uterine tissue from this mouse model, when focusing on genes regulated by estrogen and TSC2, we discovered significant upregulation of inflammatory proteases such as Neutrophil Elastase (NE). NE is secreted by myeloid cells such as polymorphonuclear cells (PMNs) and has been reported to promote invasion, migration, and proliferation in various cancers. We found this to be true in LAM as well, as depleting myeloid cells with an antibody directed against PMNs, or inhibiting NE with the NE inhibitor, sivelestat, markedly decreased TSC2-null uterine tumor growth. NE is released when PMNs undergo Neutrophil Extracellular Trap release, or NETosis. NETosis has been shown to have a pro-tumorigenic role in various cancers and we are investigating the effects of NETosis in LAM. We have also generated a novel uterine-specific TSC2-null mouse in the background of no NE to determine whether uterine tumor burden and lung metastases are reduced in NE-null mice and if these mice have PMNs capable of undergoing NETosis in the absence of NE. Overall, our results suggest that NE release from PMNs is critical for LAM tumor development and may be a novel target for its treatment.

CRISPR/Cas9 Mediated ELANE Knock-out Restores Survival and Granulocytic Differentiation of HL60 Cells Expressing Mutant Neutrophil Elastase: Is Neutrophil Elastase a Dispensible Granulocyte Protease?

Background : Mutations in ELANE are the most common cause of both cyclic and severe congenital neutropenia. ELANE encodes neutrophil elastase (NE), a tissue specific serine protease expressed primarily in neutrophils. Expression of the mutant protein impairs survival and maturation of myeloid precursors in bone marrow. More than 130 different ELANE mutations have been found in patients with cyclic and congenital neutropenia, and genotype-phenotype studies suggest that specific mutations cause more severe disease. (Curr Op Hematol. 2015;22:3-11) Mutant NE is also implicated as the primary cause of ELANE associated neutropenia by studies showing that cell permeable inhibitors of NE correct the defect in cell survival and maturation in cellular models. (Makaryan et al. J Leukoc Biol. 2017;102:1143). Hypothesis: If inhibition of NE can correct the cellular defect, deletion of ELANE will have similar effects and permit studies to see if NE is an essential neutrophil protease. Methods: We used CRISPR/Cas9 mediated gene editing to create a cellular model of congenital neutropenia in the commercially available human promyelocytic cell line, HL60. We used CRISPR/Cas9 editing technology to create engineered HL60 cell lines with knock-in (KI) ELANE P139L, C151Y and G214R single point heterozygous mutations. Using the same technology, we then performed ELANE gene complete knock out (KO) of ELANE in each mutant cell line. All engineered cell lines as well as wild-type HL60 cells were cultured for 5-7 days in complete RPMI supplemented with 2uM all-trans retinoic acid (ATRA) to trigger myeloid differentiation. Survival of these cell lines was investigated using Annexin V-PE staining and flow cytometric analysis. Granulocytic differentiation was evaluated using CD11b surface marker staining and flow cytometry and by performing manual differential cell counts. We measured the unfolded protein response (UPR) by western blotting using UPR specific antibodies, phagocytosis with E. coli particles using fluorescence detection, IL-8 stimulated chemotaxis in trans-well system and PMA activated respiratory burst by flow cytometry. Results: Cells expressing the P139L and C151Y mutant ELANE had increased Annexin V staining more than a 2-fold increase in apoptotic cells at 7 days in culture. Granulocytic differentiation, measured by surface CD11b expression, was significantly impaired. (p<0.0001). Cytospins stained with Diff-Quik showed a typical block of myeloid differentiation and a significant deficiency of mature neutrophils in 7-day cultures. Western blot analysis using antibodies to GRP78/BiP and ATF6 showed a typical UPR signature in both ELANE mutant cell lines compared to wild type. Chemotaxis to the IL8 chemo-attractant was severely impaired in cells expressing mutant NE. Respiratory burst and phagocytosis was also altered in cells expressing mutant NE. ELANE KO corrected all these cellular and functional abnormalities, reverting these functions toward the wild phenotype. Studies are in progress for the third cell line expressing the G214R mutation. Conclusions: CRISPR/Cas9 engineered HL60 cell lines expressing mutant NE are a highly reproducible and reliable cellular model for investigating ELANE associated neutropenia. The presence of mutant NE severely impairs neutrophil functions, and its deletion through KO of ELANE corrects the cellular abnormalities and reverses the induced abnormalities. These results suggest that CRISPR/Cas9 mediated genetic knock down of NE is a novel therapeutic approach for treatment of this disorder. This data also suggests that total absence of NE does not alter basic functions of granulocytes. Disclosures Dale: Sanofi Aventis: Consultancy, Honoraria; Athelas: Equity Ownership; Amgen: Consultancy, Research Funding; Cellerant: Other: Scientific Advisory Board; Hospira: Consultancy; Prolong: Consultancy; Beheringer/Ingelheim: Consultancy; Coherus: Consultancy; x4pharma: Consultancy, Honoraria, Research Funding.

Neutrophil Elastase Subverts the Immune Response by Cleaving Toll-Like Receptors and Cytokines in Pneumococcal Pneumonia.

Excessive activation of neutrophils results in the release of neutrophil elastase (NE), which leads to lung injury in severe pneumonia. Previously, we demonstrated a novel immune subversion mechanism involving microbial exploitation of this NE ability, which eventually promotes disruption of the pulmonary epithelial barrier. In the present study, we investigated the effect of NE on host innate immune response. THP-1-derived macrophages were stimulated with heat-killed Streptococcus pneumoniae or lipopolysaccharide in the presence or absence of NE followed by analysis of toll-like receptor (TLR) and cytokine expression. Additionally, the biological significance of NE was confirmed in an in vivo mouse intratracheal infection model. NE downregulated the gene transcription of multiple cytokines in THP-1-derived macrophages through the cleavage of TLRs and myeloid differentiation factor 2. Additionally, NE cleaved inflammatory cytokines and chemokines. In a mouse model of intratracheal pneumococcal challenge, administration of an NE inhibitor significantly increased proinflammatory cytokine levels in bronchoalveolar lavage fluid, enhanced bacterial clearance, and improved survival rates. Our work indicates that NE subverts the innate immune response and that inhibition of this enzyme may constitute a novel therapeutic option for the treatment of pneumococcal pneumonia.

Neutrophil Elastase Modulates Cytokine Expression: CONTRIBUTION TO HOST DEFENSE AGAINST PSEUDOMONAS AERUGINOSA-INDUCED PNEUMONIA

There is accumulating evidence that following bacterial infection, the massive recruitment and activation of the phagocytes, neutrophils, is accompanied with the extracellular release of active neutrophil elastase (NE), a potent serine protease. Using NE-deficient mice in a clinically relevant model of Pseudomonas aeruginosa-induced pneumonia, we provide compelling in vivo evidence that the absence of NE was associated with decreased protein and transcript levels of the proinflammatory cytokines TNF-α, MIP-2, and IL-6 in the lungs, coinciding with increased mortality of mutant mice to infection. The implication of NE in the induction of cytokine expression involved at least in part Toll-like receptor 4 (TLR-4). These findings were further confirmed following exposure of cultured macrophages to purified NE. Together, our data suggest strongly for the first time that NE not only plays a direct antibacterial role as it has been previously reported, but released active enzyme can also modulate cytokine expression, which contributes to host protection against P. aeruginosa. In light of our findings, the long held view that considers NE as a prime suspect in P. aeruginosa-associated diseases will need to be carefully reassessed. Also, therapeutic strategies aiming at NE inhibition should take into account the physiologic roles of the enzyme.

No role for neutrophil elastase in influenza-induced cellular recruitment, cytokine production or airway hyperresponsiveness in mice

Previous studies have suggested that in vitro modulation of neutrophil chemokines and inflammatory cytokines by neutrophil elastase (NE) does not translate to the in vivo setting. We aimed to test the role of NE in the recruitment of neutrophils, cytokine production and lung function responses to respiratory viral infection. To address this, we inoculated neutrophil elastase (NE(-/-)) deficient and wild-type (WT) 129Sv mice with 50μL of 10(4.5)pfu Influenza A/Mem71 (H3N1) or a control preparation. Mice were subjected to methacholine (MCh) challenge at 3-4 days post-infection during the peak of cellular inflammation. Inflammation, protein content and cytokines (TNF-α and MIP-2) were assessed in bronchoalveolar lavage fluid. Influenza-infected mice had a heightened responsiveness to MCh, increased cellular inflammation, increased protein leak and altered cytokine production, none of which were influenced by the absence of NE. These data demonstrate that NE does not modulate neutrophil recruitment, cytokine production, epithelial permeability or responsiveness to bronchoconstricting agents during acute influenza infection in mice.

Neutrophil Elastase Is Needed for Neutrophil Emigration into Lungs in Ventilator-Induced Lung Injury

Mechanical ventilation, often required to maintain normal gas exchange in critically ill patients, may itself cause lung injury. Lung-protective ventilatory strategies with low tidal volume have been a major success in the management of acute respiratory distress syndrome (ARDS). Volutrauma causes mechanical injury and induces an acute inflammatory response. Our objective was to determine whether neutrophil elastase (NE), a potent proteolytic enzyme in neutrophils, would contribute to ventilator-induced lung injury. NE-deficient (NE-/-) and wild-type mice were mechanically ventilated at set tidal volumes (10, 20, and 30 ml/kg) with 0 cm H2O of positive end-expiratory pressure for 3 hours. Lung physiology and markers of lung injury were measured. Neutrophils from wild-type and NE-/- mice were also used for in vitro studies of neutrophil migration, intercellular adhesion molecule (ICAM)-1 cleavage, and endothelial cell injury. Surprisingly, in the absence of NE, mice were not protected, but developed worse ventilator-induced lung injury despite having lower numbers of neutrophils in alveolar spaces. The possible explanation for this finding is that NE cleaves ICAM-1, allowing neutrophils to egress from the endothelium. In the absence of NE, impaired neutrophil egression and prolonged contact between neutrophils and endothelial cells leads to tissue injury and increased permeability. NE is required for neutrophil egression from the vasculature into the alveolar space, and interfering with this process leads to neutrophil-related endothelial cell injury.

Mice Lacking Neutrophil Elastase Are Resistant to Bleomycin-Induced Pulmonary Fibrosis

Neutrophil elastase is a serine protease stored in the azurophilic granules of leukocytes. It has been implicated in the pathology of several lung diseases and is generally presumed to contribute to the tissue destruction and extracellular matrix damage associated with these conditions. To delineate the role of neutrophil elastase in pulmonary inflammation and fibrosis, neutrophil elastase-null mice were intratracheally instilled with bleomycin. In neutrophil elastase-null mice, biochemical and morphological characteristics of pulmonary fibrosis were attenuated for at least 60 days after bleomycin administration despite a typical response to bleomycin as evidenced by assessment of indices of DNA and cell damage. Neutrophil burden of bleomycin-treated wild-type and neutrophil elastase-null mice was comparable, and marked neutrophilic alveolitis was manifest in bleomycin-treated neutrophil elastase-null mice. An absence of immunostaining for active transforming growth factor (TGF)-beta in lung tissue from bleomycin-treated neutrophil elastase-null mice suggested a defect in TGF-beta activation, which was confirmed by biochemical assessment of TGF-beta levels in bronchoalveolar lavage fluid and lung tissue. These data point to novel and unexpected fibrogenic consequences of neutrophil elastase activity in the inflamed lung.

Neutropenia-Associated Mutations of PFAAP5, a Novel Protein Mediating Transcriptional Repressor Interaction between Gfi1 and Neutrophil Elastase.

Mutations in ELA2, encoding the protease neutrophil elastase, cause cyclic neutropenia and are also the most common cause of the Kostmann syndrome of congenital neutropenia. Mutations in the transcriptional repressor and intrinsic regulator of hematopoiesis, Gfi1, are another rare cause of congenital neutropenia. ELA2 is a target of Gfi1; consequently, mutation of Gfi1 leads to over-expression of neutrophil elastase. Defects in a predicted feedback circuit offer a possible explanation for the periodic oscillations of cyclic neutropenia, but how neutrophil elastase and Gfi1 regulate hematopoiesis with respect to each other, and what additional factors may be involved, has remained undefined.To identify other components of a potential hematopoietic feedback circuit, we performed yeast two-hybrid screens with Gfi1 and neutrophil elastase using bone marrow cDNA libraries. We found 25 proteins that interacted with Gfi1. Only two proteins, however, interacted with the isoform of neutrophil elastase containing an intact carboxyl terminal extension (deletion of which is the most frequently occurring type of mutation in congenital neutropenia). Remarkably, one of the two, the previously uncharacterized protein PFAAP5, was among the 25 found to also interact with Gfi1. PFAAP5 may therefore play a unique role in mediating interactions between neutrophil elastase and Gfi1.We further studied PFAAP5. Immunofluorescent localization with an epitope-tagged construct transfected into cultured cells demonstrates its localization in the nucleus. To determine if PFAAP5 influences Gfi1's activities as a transcription factor in the presence or absence of neutrophil elastase, we performed transient transfection assays with a Gfi1 responsive reporter and PFAAP5 siRNA knockdown in NIH3T3 cells, which express PFAAP5, but not Gfi1 or neutrophil elastase, endogenously. Not surprisingly, transfected neutrophil elastase demonstrated no effect as a transcriptional repressor by itself. Unexpectedly, however, transcriptional repression by transfected Gfi1 increased with co-expression of neutrophil elastase. Knockdown of PFAAP5 had no effect on transfected Gfi1 repressor activity alone, but knockdown of PFAAP5 blocked the ability of co-expressed neutrophil elastase to increase Gfi1 repressor activity. Therefore, neutrophil elastase can increase Gfi1 repressor function, but only in the presence of PFAAP5.Finally, we evaluated PFAAP5 as a candidate gene in cases of congenital neutropenia in which ELA2 or Gfi1 mutations are absent. One homozygous and two different heterozygous coding sequence substitutions were detected in four of 230 unrelated patients, yet absent among double the number of controls. The mutations prevent PFAAP5 from interacting with either neutrophil elastase or Gfi1 in the yeast two-hybrid assay. Thus, mutations of neutrophil elastase, Gfi1, or PFAAP5 may each similarly disrupt a common circuit in which Gfi1 represses ELA2 and neutrophil elastase feeds back to cooperate with Gfi1 in regulating its own transcription.

Neutrophil Elastase Contributes to Cigarette Smoke-Induced Emphysema in Mice

To address the role of neutrophil elastase in pulmonary emphysema, neutrophil elastase-deficient mice and wild-type littermate controls were exposed to long-term cigarette smoke. Compared to wild-type littermates, mice that were deficient in neutrophil elastase were significantly protected (59%) from the development of emphysema. Previously, we demonstrated complete protection from emphysema in the absence of macrophage elastase. Further analysis revealed several interactions between these two elastases. Each elastase inactivated the endogenous inhibitor of the other, with neutrophil elastase degrading tissue inhibitor of metalloproteinase-1, and macrophage elastase degrading alpha-1-antitrypsin. Cigarette smoke-induced recruitment of both neutrophils and monocytes was impaired in the absence of neutrophil elastase. Moreover, there was less macrophage elastase activity secondary to decreased macrophage accumulation in neutrophil elastase-deficient mice. This study demonstrates a direct role for neutrophil elastase in emphysema and highlights the interdependence of the proteinases and inflammatory cells that mediate lung destruction in response to cigarette smoke.

Deficiency in neutrophil elastase does not impair neutrophil recruitment to inflamed sites.

To reach the sites of inflammation, neutrophils traverse the endothelium, its underlying basement membrane, and other barriers depending on the localization of the insulting agent. Whether neutrophil elastase (NE) plays a role in neutrophil recruitment to inflamed sites is still debatable. By exploiting mice deficient in NE (NE(-/-)), we sought to address this dilemma. We recruited neutrophils to the lungs or the peritoneum of wild-type (WT) or NE(-/-) mice by intranasal or intraperitoneal challenge with Pseudomonas aeruginosa or its lipopolysaccharide. At designated times post-inoculation (0, 4, 24, and 48 h), groups of mice were killed to assess changes in leukocyte counts and inflammatory responses. NE(-/-) and WT mice had normal circulating leukocyte numbers including neutrophils and changes in the hemograms in the setting of acute inflammation were indistinguishable. Analyses of lung tissues or fluids from the lungs and peritoneum found that regardless of the inflammatory model, the leukocyte counts including neutrophils and the inflammatory response were similar in NE(-/-) and WT mice at all time points. In vitro, neutrophils isolated from the lungs or the peritoneum of NE(-/-) and WT mice had comparable chemotactic and respiratory-burst functions and migrated normally through Matrigel in response to various stimuli. Interestingly, preincubation of human peripheral blood neutrophils with NE physiologic inhibitors did not alter the migration of the cells through Matrigel. In sum, our findings present the first in vivo description that the absence of NE does not impair neutrophil recruitment to inflamed sites and that NE is not required for basement membrane transmigration of neutrophils.

Neutrophil Elastase Cleaves PML-RARα and Is Important for the Development of Acute Promyelocytic Leukemia in Mice

The fusion protein PML-RARα, generated by the t(15;17)(q22;q11.2) translocation associated with acute promyelocytic leukemia (APL), initiates APL when expressed in the early myeloid compartment of transgenic mice. PML-RARα is cleaved in several positions by a neutral serine protease in a human myeloid cell line; purification revealed that the protease is neutrophil elastase (NE). Immunofluorescence localization studies suggested that the cleavage of PML-RARα must occur within the cell, and perhaps, within the nucleus. The functional importance of NE for APL development was assessed in NE deficient mice. Greater than 90% of bone marrow PML-RARα cleaving activity was lost in the absence of NE, and NE (but not Cathepsin G) deficient animals were protected from APL development. Primary mouse and human APL cells also contain NE-dependent PML-RARα cleaving activity. Since NE is maximally produced in promyelocytes, this protease may play a role in APL pathogenesis by facilitating the leukemogenic potential of PML-RARα.

It's moving day: factors affecting peripheral blood stem mobilization and strategies for improvement

It's moving day: factors affecting peripheral blood stem mobilization and strategies for improvement

Degradation of outer membrane protein A in Escherichia coli killing by neutrophil elastase.

In determining the mechanism of neutrophil elastase (NE)-mediated killing of Escherichia coli, we found that NE degraded outer membrane protein A (OmpA), localized on the surface of Gram-negative bacteria. NE killed wild-type, but not OmpA-deficient, E. coli. Also, whereas NE-deficient mice had impaired survival in response to E. coli sepsis, as compared to wild-type mice, the presence or absence of NE had no influence on survival in response to sepsis that had been induced with OmpA-deficient E. coli. These findings define a mechanism of nonoxidative bacterial killing by NE and point to OmpA as a bacterial target in host defense.

Impaired Immunity and Enhanced Resistance to Endotoxin in the Absence of Neutrophil Elastase and Cathepsin G

While the critical role of reactive oxygen intermediates (ROI) in the microbicidal activity of polymorphonuclear granulocytes is well established, the function of the nonoxidative effector mechanisms in vivo remains unclear. Here we show that mice deficient in the neutrophil granule serine proteases elastase and/or cathepsin G are susceptible to fungal infections, despite normal neutrophil development and recruitment. The protease deficiencies but not the absence of ROI leads to enhanced resistance to the lethal effects of endotoxin LPS, although normal levels of TNFα are produced. The data demonstrate a critical role of the nonoxidative effector mechanisms of neutrophils in host immunity and immunopathology and identify elastase and cathepsin G as effectors in the endotoxic shock cascade downstream of TNFα.

Mice lacking neutrophil elastase reveal impaired host defense against gram negative bacterial sepsis.

Neutrophil elastase (NE) is a potent serine proteinase whose expression is limited to a narrow window during myeloid development. In neutrophils, NE is stored in azurophil granules along with other serine proteinases (cathepsin G, proteinase 3 and azurocidin) at concentrations exceeding 5 mM. As a result of its capacity to efficiently degrade extracellular matrix, NE has been implicated in a variety of destructive diseases. Indeed, while much interest has focused on the pathologic effects of this enzyme, little is known regarding its normal physiologic function(s). Because previous in vitro data have shown that NE exhibits antibacterial activity, we investigated the role of NE in host defense against bacteria. Generating strains of mice deficient in NE (NE-/-) by targeted mutagenesis, we show that NE-/- mice are more susceptible than their normal littermates to sepsis and death following intraperitoneal infection with Gram negative (Klebsiella pneumoniae and Escherichia coli) but not Gram positive (Staphylococcus aureus) bacteria. Our data indicate that neutrophils migrate normally to sites of infection in the absence of NE, but that NE is required for maximal intracellular killing of Gram negative bacteria by neutrophils.