Neutrophil elastase-deficient mice form neutrophil extracellular traps in an experimental model of deep vein thrombosis

ESSENTIALS: Neutrophil elastase (NE) plays a role in extracellular trap formation (NETosis) triggered by microbes. The contribution of NE was evaluated in mouse NETosis models of sterile inflammation and thrombosis. NE is not required for mouse neutrophil NET production in vitro with non-infectious stimuli. NE deficiency had no significant effect on thrombosis in the inferior vena cava stenosis model.

SUMMARY

BACKGROUND

Neutrophil serine proteases have been implicated in coagulation and neutrophil extracellular trap (NET) formation. In human neutrophils, neutrophil elastase (NE) translocates to the nucleus during NETosis and cleaves histones, thus aiding in chromatin decondensation. NE(-/-) mice were shown not to release NETs in response to microbes. However, mouse studies evaluating the role of NE in NET formation in sterile inflammation and thrombosis are lacking.

OBJECTIVE

We wished to establish if neutrophils from NE(-/-) mice have a defect in NETosis, similar to peptidylarginine deiminase 4 (PAD4(-/-)) mice, and how this might have an impact on venous thrombosis, a model where NETs are produced and are crucial to thrombus development.

METHODS

We performed in vitro NET assays using neutrophils from wild-type (WT), NE(-/-), SerpinB1 (SB1)(-/-) and NE(-/-) SB1(-/-) mice. We compared WT and NE(-/-) animals using the inferior vena cava stenosis model of deep vein thrombosis (DVT).

RESULTS

Neutrophil elastase deficiency resulted in a small reduction in ionomycin-induced NET formation in vitro without affecting histone citrullination. However, NET production in response to phorbol 12-myristate 13-acetate or platelet activating factor was normal in neutrophils from two independent NE-deficient mouse lines, and in NE(-/-) SB1(-/-) as compared with SB1(-/-) neutrophils. NE deficiency or inhibition did not prevent NETosis in vivo or DVT outcome.

CONCLUSIONS

Neutrophil elastase is not required for NET formation in mice. NE(-/-) mice, which form pathological venous thrombi containing NETs, do not phenocopy PAD4(-/-) mice in in vitro NETosis assays or experimental venous thrombosis. Our study suggests that NET-targeted therapies need to be highly effective to have an impact on DVT.

Volatile and organic compositions of sedimentary rocks in Yellowknife Bay, Gale crater, Mars

H2O, CO2, SO2, O2, H2, H2S, HCl, chlorinated hydrocarbons, NO, and other trace gases were evolved during pyrolysis of two mudstone samples acquired by the Curiosity rover at Yellowknife Bay within Gale crater, Mars. H2O/OH-bearing phases included 2:1 phyllosilicate(s), bassanite, akaganeite, and amorphous materials. Thermal decomposition of carbonates and combustion of organic materials are candidate sources for the CO2. Concurrent evolution of O2 and chlorinated hydrocarbons suggests the presence of oxychlorine phase(s). Sulfides are likely sources for sulfur-bearing species. Higher abundances of chlorinated hydrocarbons in the mudstone compared with Rocknest windblown materials previously analyzed by Curiosity suggest that indigenous martian or meteoritic organic carbon sources may be preserved in the mudstone; however, the carbon source for the chlorinated hydrocarbons is not definitively of martian origin.

A serpinB1 regulatory mechanism is essential for restricting neutrophil extracellular trap generation

NETosis (neutrophil extracellular trap [NET] generation), a programmed death pathway initiated in mature neutrophils by pathogens and inflammatory mediators, can be a protective process that sequesters microbes and prevents spread of infection, but it can also be a pathological process that causes inflammation and serious tissue injury. Little is known about the regulatory mechanism. Previously, we demonstrated that serpinb1-deficient mice are highly susceptible to pulmonary bacterial and viral infections due to inflammation and tissue injury associated with increased neutrophilic death. In this study, we used in vitro and in vivo approaches to investigate whether SerpinB1 regulates NETosis. We found that serpinb1-deficient bone marrow and lung neutrophils are hypersusceptible to NETosis induced by multiple mediators in both an NADPH-dependent and -independent manner, indicating a deeply rooted regulatory role in NETosis. This role is further supported by increased nuclear expansion (representing chromatin decondensation) of PMA-treated serpinb1-deficient neutrophils compared with wild-type, by migration of SerpinB1 from the cytoplasm to the nucleus of human neutrophils that is coincident with or preceding early conversion of lobulated (segmented) nuclei to delobulated (spherical) morphology, as well as by the finding that exogenous human recombinant SerpinB1 abrogates NET production. NETosis of serpinb1-deficient neutrophils is also increased in vivo during Pseudomonas aeruginosa lung infection. The findings identify a previously unrecognized regulatory mechanism involving SerpinB1 that restricts the production of NETs.

Critical role of serpinB1 in regulating inflammatory responses in pulmonary influenza infection

BACKGROUND

Excessive inflammatory host response increases morbidity and mortality associated with seasonal respiratory influenza, and highly pathogenic virus strains are characterized by massive infiltration of monocytes and/or macrophages that produce a storm of injurious cytokines.

METHODS

Here, we examined the role in respiratory influenza of serpinB1, an endogenous inhibitor of the serine proteases elastase, cathepsin G, and proteinase-3, increasingly recognized as regulators of inflammation.

RESULTS

After challenge with high-dose surfactant protein-D (SP-D)-sensitive influenza A/Philadelphia/82 (H3N2), serpinB1(-/-) mice died earlier and in greater numbers than did wild-type mice. Sublethally infected animals suffered increased morbidity, delayed resolution of epithelial injury, and increased immune cell death. Viral clearance and SP-D/SP-A upregulation were unimpaired and so were early virus-induced cytokine and chemokine burst and influx of large numbers of neutrophils and monocytes. Whereas initial cytokines and chemokines rapidly cleared in wild-type mice, TNF-α, IL-6, KC/CXCL1, G-CSF, IL-17A, and MCP-1/CCL2 remained elevated in serpinB1(-/-) mice. Monocyte-derived cells were the dominant immune cells in influenza-infected lungs, and those from serpinB1(-/-) mice produced excessive IL-6 and TNF-α when tested ex vivo. Pulmonary γδ T-cells that produced IL-17A were also increased.

CONCLUSIONS

Because viral clearance was unimpaired, the study highlights the critical role of serpinB1 in mitigating inflammation and restricting pro-inflammatory cytokine production in influenza infection.

Development of solid-phase enzyme-linked immunosorbent assays for the determination of epidermal growth factor receptor and pp60c-src tyrosine protein kinase activity

Solid-phase ELISAs for the determination of EGF receptor (EGF-R) and pp60c-src tyrosine protein kinase activity are described. The methods were developed and optimized using purified recombinant EGF-R intracellular domain (ICD) and pp60c-src tyrosine protein kinases. A standardized assay that utilizes poly (GluNa-Tyr)4:1 as substrate and a monoclonal antiphosphotyrosine antibody for detection is described. Assay conditions for both enzymes were optimized with respect to substrate and ELISA plate-coating condition, divalent metal ion preferences, enzyme concentration, apparent kinetic constants for ATP, and reaction linearity. Following standardization, a number of reference tyrosine protein kinase inhibitors were tested in the ELISAs and compared to results obtained using solution-phase radioactive tyrosine protein kinase assays, which are based on the transfer of 32P from [gamma-32P]ATP to synthetic substrate. To enable a comprehensive comparison, IC50 values obtained in the ELISA were compared with values obtained in radioactive assays using both the holo-EGF-R and EGF-R ICD kinases. No substantial qualitative differences between these assays were seen. For many routine tyrosine protein kinase assays, semiquantitative or qualitative measurement of TPK activity is adequate. For such purposes, the ELISAs would be an attractive alternative to radioactive assays.

SerpinB1 regulates homeostatic expansion of IL-17+ γδ and CD4+ Th17 cells

SerpinB1 is an endogenous inhibitor of serine proteases recognized for its anti-inflammatory and host-protective properties. Although loss of serpinB1 in mice does not result in gross immune deregulation, serpinb1a(-/-) mice display increased mortality and inflammation-associated morbidity upon challenge with influenza virus. Here, we show that IL-17A(+) γδ and CD4(+) Th17 cells are already expanded in the lungs of serpinb1a(-/-) mice at steady-state. Both γδ and αβ(+) CD4(+) CCR6(+) T cells isolated from the lungs of naive serpinb1a(-/-) mice displayed a skewed transcriptional profile relative to WT cells, including increased Th17 signature transcripts [Il17a, l17f, and Rorc (RORγt)] and decreased Th1 signature transcripts [Ifng, Cxcr3, and Tbx21 (T-bet)] in γδ T cells. In addition to the lung, IL-17A(+) γδ and CD4(+) Th17 cells were increased in the spleen of naive serpinb1a(-/-) mice, despite normal αβ and γδ T cell development in the thymus. Within the γδ T cell compartment, loss of serpinb1a prompted selective expansion of Vγ4(+) and Vγ6/Vδ1(+) cells, which also displayed elevated expression of the proliferating cell nuclear antigen, Ki-67, and IL-17A. Given that serpinb1a is preferentially expressed in WT IL-17A(+) γδ and CD4(+) Th17 cell subsets vis-à-vis other T cell lineages, our findings reveal a novel function of serpinB1 in limiting untoward expansion of lymphocytes with a Th17 phenotype.

Cocaine promotes both initiation and elongation phase of HIV-1 transcription by activating NF-κB and MSK1 and inducing selective epigenetic modifications at HIV-1 LTR

Cocaine accelerates human immunodeficiency virus (HIV-1) replication by altering specific cell-signaling and epigenetic pathways. We have elucidated the underlying molecular mechanisms through which cocaine exerts its effect in myeloid cells, a major target of HIV-1 in central nervous system (CNS). We demonstrate that cocaine treatment promotes HIV-1 gene expression by activating both nuclear factor-kappa B (NF-ĸB) and mitogen- and stress-activated kinase 1 (MSK1). MSK1 subsequently catalyzes the phosphorylation of histone H3 at serine 10, and p65 subunit of NF-ĸB at 276th serine residue. These modifications enhance the interaction of NF-ĸB with P300 and promote the recruitment of the positive transcription elongation factor b (P-TEFb) to the HIV-1 LTR, supporting the development of an open/relaxed chromatin configuration, and facilitating the initiation and elongation phases of HIV-1 transcription. Results are also confirmed in primary monocyte derived macrophages (MDM). Overall, our study provides detailed insights into cocaine-driven HIV-1 transcription and replication.

The COPD critical pathway: a case study in progress

Patients with chronic obstructive pulmonary disease (COPD) consume many health care resources and require complex coordination of care among multiple caregivers. In this report, we share our experiences at Fletcher Allen Health Care, Burlington, Vermont, in developing and implementing a critical pathway for these patients. The COPD pathway has resulted in measurable improvements in the quality of care and has provided us with lessons that will enhance our use of critical pathway methods.

Increased surfactant protein D fails to improve bacterial clearance and inflammation in serpinB1-/- mice

Previously, we described the protective role of the neutrophil serine protease inhibitor serpinB1 in preventing early mortality of Pseudomonas aeruginosa lung infection by fostering bacterial clearance and limiting inflammatory cytokines and proteolytic damage. Surfactant protein D (SP-D), which maintains the antiinflammatory pulmonary environment and mediates bacterial removal, was degraded in infected serpinB1-deficient mice. Based on the hypothesis that increased SP-D would rescue or mitigate the pathological effects of serpinB1 deletion, we generated two serpinB1(-/-) lines overexpressing lung-specific rat SP-D and inoculated the mice with P. aeruginosa. Contrary to predictions, bacterial counts in the lungs of SP-D(low)serpinB1(-/-) and SP-D(high) serpinB1(-/-) mice were 4 logs higher than wild-type and not different from serpinB1(-/-) mice. SP-D overexpression also failed to mitigate inflammation (TNF-α), lung injury (free protein, albumin), or excess neutrophil death (free myeloperoxidase, elastase). These pathological markers were higher for infected SP-D(high)serpinB1(-/-) mice than for serpinB1(-/-) mice, although the differences were not significant after controlling for multiple comparisons. The failure of transgenic SP-D to rescue antibacterial defense of serpinB1-deficient mice occurred despite 5-fold or 20-fold increased expression levels, largely normal structure, and dose-dependent bacteria-aggregating activity. SP-D of infected wild-type mice was intact in 43-kD monomers by reducing SDS-PAGE. By contrast, proteolytic fragments of 35, 17, and 8 kD were found in infected SP-D(low)serpinB1(-/-), SP-D(high) serpinB1(-/-) mice, and serpinB1(-/-) mice. Thus, although therapies to increase lung concentration of SP-D may have beneficial applications, the findings suggest that therapy with SP-D may not be beneficial for lung inflammation or infection if the underlying clinical condition includes excess proteolysis.

Randomised controlled trial of a psychotherapeutic intervention to improve quality of life and other outcomes in people who repeatedly self-harm: FReSH START study protocol

BACKGROUND

Self-harm is a major public health challenge, and repeated self-harm is common in those attending hospital following an episode. Evidence suggests psychological interventions could help people who self-harm, but few definitive studies have assessed their clinical and cost-effectiveness. Repeated self-harm is associated with poor quality of life, depression, suicide and increased health service costs which justify the development of psychotherapeutic interventions tailored for people with repeated self-harm.

METHODS

FReSH START is a multicentre individually 1:1 randomised controlled trial evaluating the clinical and cost-effectiveness of standard care plus psychological therapy or standard care alone for adults (≥ 18 years) presenting at an emergency department (ED) with repeated self-harm. Recruiting 630 participants, it includes an internal pilot, economic evaluation and process evaluation. The intervention will be delivered by mental health staff working in acute settings, with experience of assessing and managing risk in people presenting to emergency services with self-harm. Staff will be trained and supervised to deliver one of three specially adapted therapies: psychodynamic interpersonal therapy, cognitive behavioural therapy or acceptance and commitment therapy. Participants allocated to the intervention will receive one of the adapted therapies according to therapist allocation for up to 6 months via 12 weekly, one to one, 45-50-min sessions. The primary outcome is quality of life measured by the Clinical Outcomes in Routine Evaluation Outcome Measure at 12 months post-randomisation. Secondary outcomes include suicidal intent, depression and cost-effectiveness. Data are collected using hospital attendance records and online/postal/telephone questionnaires at 6 and 12 months post-randomisation, with resource use additionally collected at 3 and 9 months.

DISCUSSION

This protocol outlines a randomised controlled trial to investigate whether modified therapies are cost-effective and improve quality of life for people who repeatedly self-harm. Few interventions are proven to be deliverable in the NHS for this population. This study is strengthened by the involvement of qualified mental health workers experienced in managing risk as therapists.

TRIAL REGISTRATION

Registered on August 03, 2021. IRAS number: 297939. ISRCTN: https://doi.org/10.1186/ISRCTN73357210 . REC reference: 21/EE/0145.

SPONSOR

University of Leeds.

A research-based risk assessment tool as the cornerstone of a pressure ulcer prevention program

By highlighting theories of knowledge utilization, we consider some of the factors and issues in planning research utilization projects. By our use of a research utilization model in developing a research-based pressure ulcer prevention program, we help to bridge the gap between research and practice.

A chemotherapy standard order form: preventing errors

PURPOSE/OBJECTIVES

To describe the development and implementation of one approach to standardize and document chemotherapy orders for patients in the acute-care setting.

DATA SOURCES

Multidisciplinary team, Oncology Nursing Society standards of care, clinical experience, and published literature.

DATA SYNTHESIS

To avoid errors in ordering, dispensing, and administering chemotherapy that may have the potential for serious adverse patient outcomes, a standardized order sheet was developed to consistently document information regarding chemotherapy ordering and administration throughout the hospital. Each component of the form is essential in promoting safety and efficiency in the chemotherapy ordering and administration process.

CONCLUSION

A standardized approach dramatically improved ordering, dispensing, and administering chemotherapy. Multidisciplinary verification and documentation of dose and schedule helps reduce chemotherapy-related errors.

IMPLICATIONS FOR NURSING PRACTICE

The chemotherapy order sheet saves time and is comprehensive and consistent. Use of the order sheet also has increased interdisciplinary collaboration and assisted all members of the team in documenting required information.

SerpinB1 is essential for regulation of neutrophil extracellular trap (NET) generation (118.3)

NETosis, a programmed death pathway induced in mature neutrophils by pathogens and inflammatory mediators, can be either a protective process that prevents spread of microbial infection or a pathological process that causes severe tissue damage and inflammation. Little is known about the mechanisms that regulate such a diverse functional spectrum. Previously we demonstrated serpinB1 null mice are highly susceptible to pulmonary Pseudomonas aeruginosa infection due to increased pathology mediated neutrophilic death. Using in vitro and in vivo approaches we examine the regulatory role of SerpinB1 in NETosis. We found bone marrow or LPS-derived serpinB1 null neutrophils are remarkably prone to NETosis in both NADPH-dependent and independent manner. A regulatory role for SerpinB1 in NETosis is also supported by the increased number of neutrophils with expanded nuclei, likely representing chromatin decondensation, and by finding that exogenous rSERPINB1 abrogates NET production. Importantly, during P. aeruginosa lung infection 4 times more NETs were harvested from serpinb1-/- mice than WT mice. The total number of in vitro activated serpinB1-/- neutrophils that died was not different from wild-type, indicating that the primary protective role of SerpinB1 is determining whether activated neutrophils die by the highly injurious NETs mechanism or by a less phlogistic mode, generating apoptotic-like cells with shrunken appearance and small nuclei.

SerpinB1 functions in generating neutrophil extracellular traps (111.11)

SerpinB1 is a potent inhibitor of neutrophil serine proteases (NSPs), and mice deficient for serpinB1 showed reduced capacity to clear Pseudomonas aeruginosa lung infection, increase of proinflammatory cytokines and neutrophil death compared with wild type (WT) mice. Here we questioned whether this deficient anti-microbial protection might be caused by altered production of neutrophil extracellular traps (NETs). NETs, extruded chromatin associated with granule proteins including NSPs, capture and kill microbes, but excess NETs can cause tissue injury, e.g., impairment of lung function in patients with cystic fibrosis. On stimulation with phorbol myristate actetate (PMA) or platelet-activating factor (PAF), isolated bone marrow neutrophils of serpinB1-/- mice produced increased NETs compared with WT. Isolated lung neutrophils of LPS-treated serpinB1-/- mice also produced increased NETs compared with WT in response to PMA, and increased numbers of neutrophils with expanded nuclei. NET production was NADPH oxidase-dependent, and NADPH oxidase activity did not differ between the genotypes. Fluorescent microscopy showed that SerpinB1 translocated in PMA treated human neutrophils from the cytoplasm to the nucleus prior to nuclear membrane disintegration. SerpinB1 was also found as an extracellular component of NETs. These findings indicate that SerpinB1 contributes to regulation of NET formation and, by its presence in NETs, may protect against protease-induced tissue injury.