Neutrophil elastase inhibitor sivelestat ameliorates gefitinib-naphthalene-induced acute pneumonitis in mice

Essential Involvement of Neutrophil Elastase in Acute Acetaminophen Hepatotoxicity Using BALB/c Mice

Intense neutrophil infiltration into the liver is a characteristic of acetaminophen-induced acute liver injury. Neutrophil elastase is released by neutrophils during inflammation. To elucidate the involvement of neutrophil elastase in acetaminophen-induced liver injury, we investigated the efficacy of a potent and specific neutrophil elastase inhibitor, sivelestat, in mice with acetaminophen-induced acute liver injury. Intraperitoneal administration of 750 mg/kg of acetaminophen caused severe liver damage, such as elevated serum transaminase levels, centrilobular hepatic necrosis, and neutrophil infiltration, with approximately 50% mortality in BALB/c mice within 48 h of administration. However, in mice treated with sivelestat 30 min after the acetaminophen challenge, all mice survived, with reduced serum transaminase elevation and diminished hepatic necrosis. In addition, mice treated with sivelestat had reduced NOS-II expression and hepatic neutrophil infiltration after the acetaminophen challenge. Furthermore, treatment with sivelestat at 3 h after the acetaminophen challenge significantly improved survival. These findings indicate a new clinical application for sivelestat in the treatment of acetaminophen-induced liver failure through mechanisms involving the regulation of neutrophil migration and NO production.

The immunological mechanisms and therapeutic potential in drug-induced liver injury: lessons learned from acetaminophen hepatotoxicity

Acute liver failure caused by drug overdose is a significant clinical problem in developed countries. Acetaminophen (APAP), a widely used analgesic and antipyretic drug, but its overdose can cause acute liver failure. In addition to APAP-induced direct hepatotoxicity, the intracellular signaling mechanisms of APAP-induced liver injury (AILI) including metabolic activation, mitochondrial oxidant stress and proinflammatory response further affect progression and severity of AILI. Liver inflammation is a result of multiple interactions of cell death molecules, immune cell-derived cytokines and chemokines, as well as damaged cell-released signals which orchestrate hepatic immune cell infiltration. The immunoregulatory interplay of these inflammatory mediators and switching of immune responses during AILI lead to different fate of liver pathology. Thus, better understanding the complex interplay of immune cell subsets in experimental models and defining their functional involvement in disease progression are essential to identify novel therapeutic targets for the treatment of AILI. Here, this present review aims to systematically elaborate on the underlying immunological mechanisms of AILI, its relevance to immune cells and their effector molecules, and briefly discuss great therapeutic potential based on inflammatory mediators.

Organoid technology and lung injury mouse models evaluating effects of hydroxychloroquine on lung epithelial regeneration

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) damages lung epithelial stem/progenitor cells. Ideal anti-SARS-CoV-2 drug candidates should be screened to prevent secondary injury to the lungs. Here, we propose that in vitro three-dimensional organoid and lung injury repair mouse models are powerful models for the screening antiviral drugs. Lung epithelial progenitor cells, including airway club cells and alveolar type 2 (AT2) cells, were co-cultured with supportive fibroblast cells in transwell inserts. The organoid model was used to evaluate the possible effects of hydroxychloroquine, which is administered as a symptomatic therapy to COVID-19 patients, on the function of mouse lung stem/progenitor cells. Hydroxychloroquine was observed to promote the self-renewal of club cells and differentiation of ciliated and goblet cells in vitro. Additionally, it inhibited the self-renewal ability of AT2 cells in vitro. Naphthalene- or bleomycin-induced lung injury repair mouse models were used to investigate the in vivo effects of hydroxychloroquine on the regeneration of club and AT2 cells, respectively. The naphthalene model indicated that the proliferative ability and differentiation potential of club cells were unaffected in the presence of hydroxychloroquine. The bleomycin model suggested that hydroxychloroquine had a limited effect on the proliferation and differentiation abilities of AT2 cells. These findings suggest that hydroxychloroquine has limited effects on the regenerative ability of epithelial stem/progenitor cells. Thus, stem/progenitor cell-derived organoid technology and lung epithelial injury repair mouse models provide a powerful platform for drug screening, which could possibly help end the pandemic.

Hindrance of the Proteolytic Activity of Neutrophil-Derived Serine Proteases by Serine Protease Inhibitors as a Management of Cardiovascular Diseases and Chronic Inflammation

During inflammation neutrophils become activated and segregate neutrophil serine proteases (NSPs) to the surrounding environment in order to support a natural immune defense. However, an excess of proteolytic activity of NSPs can cause many complications, such as cardiovascular diseases and chronic inflammatory disorders, which will be elucidated on a biochemical and immunological level. The application of selective serine protease inhibitors is the logical consequence in the management of the indicated comorbidities and will be summarized in this briefing.

Affinity chromatography assisted comprehensive phosphoproteomics analysis of human saliva for lung cancer

Affinity chromatography is a powerful technology for phosphopeptide enrichment from body fluids. Saliva is a non-invasive body fluid for disease diagnosis, while few studies applied affinity enrichment for saliva phosphoproteome. In this study, we tested two kinds of affinity chromatography materials, Ti⁴⁺-IMAC (immobilized metal affinity chromatography) and CaTiO₃, for the enrichment of phosphopeptides. Through comparison, Ti⁴⁺-IMAC method was demonstrated as the superior one, which was utilized for the comprehensive analysis of salivary phosphoproteome. More than 360 phosphoproteins were specifically extracted and identified from human saliva. Ti⁴⁺-IMAC method was further applied to compare the phosphoprotein profiling in the saliva of lung cancer group and normal control group through label-free quantification. Accordingly, 477 and 699 phosphopeptides were enriched, respectively, which corresponded to 339 and 466 proteins. In total, 796 unique phosphopeptides were revealed for 517 saliva phosphoproteins. In particular, 709 phosphorylation sites were identified, among which 26 were up-regulated (>1.5) and 149 were down-regulated (<0.66) in lung cancer. Their corresponding proteins were mainly associated with cancer promotion, system disorder, and organismal injury. Our data collectively demonstrated that salivary phosphopeptides can be comprehensively characterized through Ti⁴⁺-IMAC method. These discovered phosphoprotein candidates might be used for lung cancer detection through salivary diagnostics.

Combination of sivelestat and N-acetylcysteine alleviates the inflammatory response and exceeds standard treatment for acetaminophen-induced liver injury

Hepatocyte death during acetaminophen (APAP) intoxication elicits a reactive inflammatory response, with hepatic recruitment of neutrophils and monocytes, which further aggravates liver injury. Neutrophil elastase (NE), secreted by activated neutrophils, carries degradative and cytotoxic functions and maintains a proinflammatory state. We investigated NE as a therapeutic target in acetaminophen-induced liver injury (AILI). C57BL/6 mice were administered a toxic dose of APAP, 2 h prior to receiving the NE inhibitor sivelestat, N-acetylcysteine (NAC), or a combination therapy, and were euthanized after 24 and 48 h. Upon APAP overdose, neutrophils and monocytes infiltrate the injured liver, accompanied by increased levels of NE. Combination therapy of NAC and sivelestat significantly limits liver damage, as evidenced by lower serum transaminase levels and less hepatic necrosis compared to mice that received APAP only, and this to a greater extent than NAC monotherapy. Lower hepatic expression of proinflammatory markers was observed in the combination treatment group, and flow cytometry revealed significantly less monocyte influx in livers from mice treated with the combination therapy, compared to untreated mice and mice treated with NAC only. The potential of NE to induce leukocyte migration was confirmed in vitro. Importantly, sivelestat did not impair hepatic repair. In conclusion, combination of NE inhibition with sivelestat and NAC dampens the inflammatory response and reduces liver damage following APAP overdose. This strategy exceeds the standard of care and might represent a novel therapeutic option for AILI.

Linking tyrosine kinase inhibitor-mediated inflammation with normal epithelial cell homeostasis and tumor therapeutic responses

Receptor tyrosine kinases (RTKs) bearing oncogenic mutations in EGFR, ALK and ROS1 occur in a significant subset of lung adenocarcinomas. Tyrosine kinase inhibitors (TKIs) targeting tumor cells dependent on these oncogenic RTKs yield tumor shrinkage, but also a variety of adverse events. Skin toxicities, hematological deficiencies, nausea, vomiting, diarrhea, and headache are among the most common, with more acute and often fatal side effects such as liver failure and interstitial lung disease (ILD) occurring less frequently. In normal epithelia, RTKs regulate tissue homeostasis. For example, EGFR maintains keratinocyte homeostasis while MET regulates processes associated with tissue remodeling. Previous studies suggest that the acneiform rash occurring in response to EGFR inhibition is a part of an inflammatory response driven by pronounced cytokine and chemokine release and recruitment of distinct immune cell populations. Mechanistically, blockade of EGFR causes a Type I interferon (IFN) response within keratinocytes and in carcinoma cells driven by this RTK. This innate immune response within the tumor microenvironment (TME) involves increased antigen presentation and effector T cell recruitment that may participate in therapy response. This TKI-mediated release of inflammatory suppression represents a novel tumor cell vulnerability that may be exploited by combining TKIs with immune-oncology (IO) agents that rely on T-cell inflammation for efficacy. However, early clinical data indicate that combination therapies enhance the frequency and magnitude of the more acute adverse events, especially pneumonitis, hepatitis, and pulmonary fibrosis. Further preclinical studies to understand TKI mediated inflammation and crosstalk between normal epithelial cells, cancer cells, and the TME are necessary to improve treatment regimens for patients with RTK-driven carcinomas.

G-CSF mediates lung injury in mice with adenine-induced acute kidney injury

Acute lung injury (ALI) is a serious complication among patients with acute kidney injury (AKI) that is a systemic inflammatory disease with high morbidity and mortality. The pathophysiology of AKI-associated ALI is poorly understood. G-CSF regulates the production and function of neutrophils that mediate lung injury via elastase and other mediators. Here, we used a mouse model of adenine-induced AKI to determine the roles of G-CSF and neutrophil elastase in AKI-associated ALI. We confirmed that ALI was associated with high serum G-CSF levels, and elevated neutrophil elastase activity in the lungs and serum of mice with adenine-induced AKI. Systemic administration of G-CSF-specific neutralizing antibody normalized granulopoiesis, pulmonary neutrophil infiltration, and neutrophil elastase activity, conferring improved lung architecture in mice with adenine-induced AKI. Further studies revealed that macrophages secreted G-CSF upon urea stimulation. Consequently, G-CSF could be a target for new anti-lung injury strategy in patients with AKI.

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.

Characteristics of systemic inflammation in hepatitis B-precipitated ACLF: Differentiate it from No-ACLF

BACKGROUND & AIMS

Patients with severe exacerbation of chronic hepatitis B (SE-CHB) are at risk of developing acute-on-chronic liver failure (ACLF). Systemic inflammation (SI) is a major driver of ACLF. The aim of this study was to identify characteristics of SI in hepatitis B-precipitated-ACLF (HB-ACLF), which may be distinct from No-ACLF patients with SE-CHB.

METHODS

Two cohorts of patients with SE-CHB were enrolled in two tertiary hospitals. The associations between circulating leucocyte counts/subsets and ACLF progression and prognoses were analysed in Cohort A. Cytokine measurements, leucocyte phenotyping and whole blood transcriptomic analyses were performed using peripheral blood samples obtained from patients in Cohort B.

RESULTS

Circulating leucocyte counts were higher in the HB-ACLF patients than in the No-ACLF patients (P < .001). Peripheral neutrophilic leucocytosis and monocytosis were associated with lymphopenia. The neutrophil-to-lymphocyte ratio (NLR) and monocyte-to-lymphocyte ratio (MLR) were correlated with risk of death in patients with SE-CHB. NLR independently predicted progression to ACLF in patients without ACLF at enrolment and short-term mortality in ACLF patients. Plasma IL-6, IL-10, G-CSF and GM-CSF levels were higher in ACLF patients (P < .05). Blood transcriptome analyses showed that genes associated with cell migration and mobility and responses to wounding and bacteria were expressed at higher levels while genes involved in lymphocyte-mediated immunity were expressed at lower levels in HB-ACLF patients than in No-ACLF patients.

CONCLUSIONS

Systemic inflammation in HB-ACLF was characterized by an excessive innate immune response, which was associated with disease progression and mortality.

Treatment with a programmed cell death-1-specific antibody has little effect on afatinib- and naphthalene-induced acute pneumonitis in mice

Although several antibodies developed to target programmed cell death-1 (PD-1) and its ligand (PD-L1) have demonstrated great promise for the treatment of non-small cell lung cancer (NSCLC), and other malignancies, these therapeutic antibodies can cause pneumonitis. Furthermore, epidermal growth factor receptor-tyrosine kinase inhibitor (EGFR-TKI)-induced pneumonitis was reported after treatment with anti PD-1 antibodies. We previously demonstrated that mice with naphthalene-induced airway epithelial injury developed severe gefitinib-induced pneumonitis through a neutrophil-dependent mechanism. The present study aimed to investigate whether treatment with afatinib, an EGFR-TKI that effectively targets EGFR mutation-positive NSCLC, and anti PD-1 antibodies induces pneumonitis in mice. C57BL/6J mice were treated intraperitoneally with naphthalene (200 mg/kg) on day 0. Afatinib (20 mg/kg) was administered orally on days -1 to 13. An anti-PD-1 antibody (0.2 mg/mice) was also administered intraperitoneally every 3 days from day 1 until day 13. The bronchoalveolar lavage fluid (BALF) and lung tissues were sampled on day 14. As observed previously with gefitinib, afatinib significantly increased the severity of histopathologic findings and the level of protein in BALF on day 14, compared to treatment with naphthalene alone. A combined anti-PD-1 antibody and afatinib treatment after naphthalene administration had yielded the same histopathological grade of lung inflammation as did afatinib treatment alone. Our results suggest that anti-PD-1 antibody treatment has little effect on afatinib-induced lung injury.