Breast cancer mortality as a function of age

Background: Incidence of breast cancer (BC) in US women continues to increase with age as the strongest risk factor. We aimed to compare clinical, pathological and sociological variables associated to BC diagnosis, as well as the relative mortality rates of BC patients compared to the general US population.

Methods: We performed a retrospective, single-institution study evaluating 52,509 patients diagnosed with unilateral BC at the University of Pittsburgh Medical Center (UPMC) between 1990–2020. Primary outcome was death from any cause with cancer recurrence as a secondary outcome, evaluated for 4 age groups: 20–44, 45–55, 56–69, and 70–90. A dataset of expected mortality for women in the general population over a 10-year period was constructed using the Surveillance, Epidemiology, and End Results (SEER) Program. Observed vs. expected mortality and standardized mortality ratios (SMR) for each age group were calculated.

Results: Youngest patients with BC demonstrated the highest SMR at 10-year follow-up from time of diagnosis compared to the general US population (SMR 9.68, 95% CI: 8.99to 10.42), and remained highest compared to other age groups when analysis was limited to Stage 0/1 disease (10-year SMR 3.11, 95% CI: 2.54 to 3.76). SMRs decreased with increasing age at diagnosis with an SMR <1.0 in patients diagnosed with stage 0/1 at ages 70–90 at 5-year follow-up.

Conclusions: Younger BC patients have the highest SMR which declines gradually with age. In the elderly, lower stage 0/1 SMR’s are found compared to the general population, suggesting the possibility of an associated protective effect.

Single cell RNA sequencing identifies IGFBP5 and QKI as ciliated epithelial cell genes associated with severe COPD

Background

Whole lung tissue transcriptomic profiling studies in chronic obstructive pulmonary disease (COPD) have led to the identification of several genes associated with the severity of airflow limitation and/or the presence of emphysema, however, the cell types driving these gene expression signatures remain unidentified.

Methods

To determine cell specific transcriptomic changes in severe COPD, we conducted single-cell RNA sequencing (scRNA seq) on n = 29,961 cells from the peripheral lung parenchymal tissue of nonsmoking subjects without underlying lung disease (n = 3) and patients with severe COPD (n = 3). The cell type composition and cell specific gene expression signature was assessed. Gene set enrichment analysis (GSEA) was used to identify the specific cell types contributing to the previously reported transcriptomic signatures.

Results

T-distributed stochastic neighbor embedding and clustering of scRNA seq data revealed a total of 17 distinct populations. Among them, the populations with more differentially expressed genes in cases vs. controls (log fold change >|0.4| and FDR = 0.05) were: monocytes (n = 1499); macrophages (n = 868) and ciliated epithelial cells (n = 590), respectively. Using GSEA, we found that only ciliated and cytotoxic T cells manifested a trend towards enrichment of the previously reported 127 regional emphysema gene signatures (normalized enrichment score [NES] = 1.28 and = 1.33, FDR = 0.085 and = 0.092 respectively). Among the significantly altered genes present in ciliated epithelial cells of the COPD lungs, QKI and IGFBP5 protein levels were also found to be altered in the COPD lungs.

Conclusions

scRNA seq is useful for identifying transcriptional changes and possibly individual protein levels that may contribute to the development of emphysema in a cell-type specific manner.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12931-021-01675-2.

Abstract PS1-10: Outcomes after sentinel lymph node biopsy and radiation therapy in women over 70 years old with ER+, HER2-, clinically node negative breast cancer

Overtreatment of early-stage breast cancer with favorable tumor biology in elderly patients can result in higher rates of complications and morbidities without impacting survival. Guidelines directed towards deimplementation of sentinel lymph node biopsy (SLNB) (Choosing Wisely) and radiation therapy (RT) (National Comprehensive Cancer Network) have been recommended. We sought to describe rates and impact on disease recurrence and survival of SLNB and RT in elderly patients with early breast cancer. Patient data were obtained from the cancer registry and electronic health record from University of Pittsburgh Medical Center, multicenter, single health care system. Consecutive female patients aged ≥ 70 with ER+, HER2- clinically node-negative breast cancer within a health care system from 2010 to 2018 were identified. Rates and patient characteristics associated with receipt of SLNB and RT, as well as local recurrence free survival (LRFS) and disease-free survival (DFS) were compared for patients that were diagnosed between 2010 and 2014 to allow for adequate follow up time. Cox proportional hazards regression was used to estimate hazard ratios (HRs) of mortality. Among 3,361 identified women, 2,195 (65.3%) received SLNB and 1,828 (54.4%) received RT. Rates of SLNB steadily increased (1.0% per year); this trend persisted in 2017 and 2018, even after the Society of Surgical Oncology adopted the Choosing Wisely Guidelines in 2016. During the same time period, rates of RT declined (3.4% per year). To examine outcomes, we limited the analysis to 2109 cases from 2010-2014; median (IQR) follow up time was 4.1 (2.5-5.7) years. Median (IQR) age was 77 (73-82) years. 1373 (65.1%) received SLNB and 1,219 (57.8%) received RT. Patients receiving SLNB were younger (P &lt; 0.001) with smaller (P &lt; 0.0001) and lower stage (P &lt; 0.0001) tumors. They had fewer comorbidities (P &lt; 0.001), longer follow-up times (P &lt; 0.001), were less likely on Medicaid/Medicare (P = 0.0091), and were more often seen at an academic center (P &lt; 0.0001). There was no difference in grade between those that did and did not receive SLNB (P = 0.31) and those that did and did not receive RT (P = 0.13). Multivariate cox proportional hazard analysis showed no effect of SLNB on LRFS (HR = 1.17, 95% CI 0.29-4.75, P = 0.83) or DFS (HR = 0.90, 95% CI 0.44-1.83, P = 0.77). Log rank test showed no difference in 5-year LRFS (P = 0.78) between patients who received (98.5%, 95% CI 97.7%-99.7%) and did not receive (98.1%, 95% CI 96.7%-99.5%) SLNB, but an increase was seen with 5-year DFS (P = 0.023), with 96.2% (95% CI 95.0%-97.4%) of patients disease-free among those who did receive SLNB vs. 93.0% (95% CI 90.6%-95.4%) with no SLNB. Multivariate cox proportional hazard analysis showed that RT was associated with improved LRFS (HR = 0.13, 95% CI 0.03-0.51, P &lt; 0.01) and DFS (HR = 0.32, 95% CI 0.15-0.68, P &lt; 0.01). Log rank test showed a difference in 5-year LRFS (P &lt; 0.0001) for those who received RT (99.4%, 95% CI 98.8%-100%) against those who did not (96.5%, 95% CI 95.0%-98.1%), and a similar difference in 5-year DFS (P &lt; 0.0001) in patients who did (97.0%, 95% CI 95.8%-98.1%) and did not (92.4%, 95% CI 90.2%-94.7%) receive RT. Lower age (OR = 0.89, 95% CI 0.87-0.92) and comorbidities (OR = 0.79, 95% CI 0.66-0.94) were associated with receipt of SLNB, while only age (OR = 0.91, 95% CI 0.88-0.94) was associated with receipt of RT.

We conclude that receipt of SLNB has no impact upon DFS or LRFS. This data supports deimplementation of SLNB for this patient population. Receipt of RT is important for controlling locoregional recurrence, supporting use of RT in this patient cohort.

Citation Format: Priscilla F McAuliffe, Neil M Carleton, Jian Zou, Yusi Fang, Stephen E Koscumb, Osama Shah, Fangyuan Chen, Sushil Beriwal, Emilia J Diego, Adam M Brufsky, Steffi Oesterreich, Steve D Shapiro, Robert Ferris, Leisha A Emens, George Tseng, Oscar C Marroquin, Adrian V Lee. Outcomes after sentinel lymph node biopsy and radiation therapy in women over 70 years old with ER+, HER2-, clinically node negative breast cancer [abstract]. In: Proceedings of the 2020 San Antonio Breast Cancer Virtual Symposium; 2020 Dec 8-11; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2021;81(4 Suppl):Abstract nr PS1-10.

Integration of mouse and human genome-wide association data identifies KCNIP4 as an asthma gene

Asthma is a common chronic respiratory disease characterized by airway hyperresponsiveness (AHR). The genetics of asthma have been widely studied in mouse and human, and homologous genomic regions have been associated with mouse AHR and human asthma-related phenotypes. Our goal was to identify asthma-related genes by integrating AHR associations in mouse with human genome-wide association study (GWAS) data. We used Efficient Mixed Model Association (EMMA) analysis to conduct a GWAS of baseline AHR measures from males and females of 31 mouse strains. Genes near or containing SNPs with EMMA p-values <0.001 were selected for further study in human GWAS. The results of the previously reported EVE consortium asthma GWAS meta-analysis consisting of 12,958 diverse North American subjects from 9 study centers were used to select a subset of homologous genes with evidence of association with asthma in humans. Following validation attempts in three human asthma GWAS (i.e., Sepracor/LOCCS/LODO/Illumina, GABRIEL, DAG) and two human AHR GWAS (i.e., SHARP, DAG), the Kv channel interacting protein 4 (KCNIP4) gene was identified as nominally associated with both asthma and AHR at a gene- and SNP-level. In EVE, the smallest KCNIP4 association was at rs6833065 (P-value 2.9e-04), while the strongest associations for Sepracor/LOCCS/LODO/Illumina, GABRIEL, DAG were 1.5e-03, 1.0e-03, 3.1e-03 at rs7664617, rs4697177, rs4696975, respectively. At a SNP level, the strongest association across all asthma GWAS was at rs4697177 (P-value 1.1e-04). The smallest P-values for association with AHR were 2.3e-03 at rs11947661 in SHARP and 2.1e-03 at rs402802 in DAG. Functional studies are required to validate the potential involvement of KCNIP4 in modulating asthma susceptibility and/or AHR. Our results suggest that a useful approach to identify genes associated with human asthma is to leverage mouse AHR association data.

Measurement of metalloproteinases

Matrix metalloproteinases (MMPs) (1,2) comprise a family of over 20 matrix degrading enzymes believed to be essential for normal development and physiologic tissue remodeling and repair. Abnormal expression of metalloproteinases has been implicated in many destructive processes, including tumor cell invasion and angiogenesis, arthritis, atherosclerosis, and arterial aneurysms. With respect to lung disease, MMPs have been associated with chronic obstructive pulmonary disease (COPD), acute lung injury, pulmonary fibrosis, and asthma. The role of MMPs in causation of pulmonary emphysema has been supported by transgenic mice overexpressing MMP-1 (3) and gene targeted mice lacking MMP-12 (4).

Annexin V decreases PS-mediated macrophage efferocytosis and deteriorates elastase-induced pulmonary emphysema in mice

Efferocytosis is believed to be a key regulator for lung inflammation in chronic obstructive pulmonary disease. In this study we pharmacologically inhibited efferocytosis with annexin V and attempted to determine its impact on the progression of pulmonary emphysema in mouse. We first demonstrated in vitro and in vivo efferocytosis experiments using annexin V, an inhibitor for phosphatidylserine-mediated efferocytosis. We then inhibited efferocytosis in porcine pancreatic elastase (PPE)-treated mice. PPE-treated mice were instilled annexin V intranasally starting from day 8 until day 20. Mean linear intercept (Lm) was measured, and cell apoptosis was assessed in lung specimen obtained on day 21. Cell profile, apoptosis, and mRNA expression of matrix metalloproteinases (MMPs) and growth factors were evaluated in bronchoalveolar lavage (BAL) cells on day 15. Annexin V attenuated macrophage efferocytosis both in vitro and in vivo. PPE-treated mice had a significant higher Lm, and annexin V further increased that by 32%. More number of macrophages was found in BAL fluid in this group. Interestingly, cell apoptosis was not increased by annexin V treatment both in lung specimens and BAL fluid, but macrophages from mice treated with both PPE and annexin V expressed higher MMP-2 mRNA levels and had a trend for higher MMP-12 mRNA expression. mRNA expression of keratinocyte growth factor tended to be downregulated. We showed that inhibited efferocytosis with annexin V worsened elastase-induced pulmonary emphysema in mice, which was, at least partly, attributed to a lack of phenotypic change in macrophages toward anti-inflammatory one.

Polymorphic variation in surfactant protein B is associated with COPD exacerbations

Exacerbations of chronic obstructive pulmonary disease (COPD) reduce quality of life and increase mortality. Genetic variation might explain the substantial variability seen in exacerbation frequency among COPD subjects with similar lung function. Polymorphisms in five candidate genes, previously associated with COPD susceptibility, were analysed in order to determine whether they demonstrated association with COPD exacerbations. A total of 88 single nucleotide polymorphisms (SNPs) in the genes microsomal epoxide hydrolase (EPHX1), transforming growth factor, beta-1 (TGFB1), serpin peptidase inhibitor, clade E (nexin, plasminogen activator inhibitor type 1), member 2 (SERPINE2), glutathione S-transferase pi (GSTP1) and surfactant protein B (SFTPB) were genotyped in 389 non-Hispanic white participants in the National Emphysema Treatment Trial. Exacerbations were defined as COPD-related emergency room visits or hospitalisations using the Centers for Medicare and Medicaid Services claims data. One or more exacerbations were experienced by 216 (56%) subjects during the study period. An SFTPB promoter polymorphism, rs3024791, was associated with COPD exacerbations. Logistic regression models, analysing a binary outcome of presence or absence of exacerbations, confirmed the association of rs3024791 with COPD exacerbations. Negative binomial regression models demonstrated association of multiple SFTPB SNPs (rs2118177, rs2304566, rs1130866 and rs3024791) with exacerbation rates. Polymorphisms in EPHX1, GSTP1, TGFB1 and SERPINE2 did not demonstrate association with COPD exacerbations. In conclusion, genetic variation in surfactant protein B is associated with chronic obstructive pulmonary disease susceptibility and exacerbation frequency.

Cathepsin S deficiency confers protection from neonatal hyperoxia-induced lung injury

RATIONALE

Bronchopulmonary dysplasia (BPD) is a chronic lung disease that adversely affects long-term pulmonary function as well as neurodevelopmental outcomes of preterm infants. Elastolytic proteases have been implicated in the pathogenesis of BPD. Cathepsin S (cat S) is a cysteine protease with potent elastolytic activity. Increased levels and activity of cat S have been detected in a baboon model of BPD.

OBJECTIVES

To investigate whether deficiency of cat S alters the course of hyperoxia-induced neonatal lung injury in mice.

METHODS

Newborn wild-type and cat S-deficient mice were exposed to 80% oxygen for 14 days. Histologic and morphometric analysis were performed and bronchoalveolar lavage protein and cells were analyzed. Lung elastin was assessed by real-time polymerase chain reaction, in situ hybridization, desmosine analysis, and Hart's stain. Distribution of myofibroblasts was analyzed by immunofluorescence. Hydroxyproline content of lung tissues was measured.

MEASUREMENTS AND MAIN RESULTS

Hyperoxia-exposed cat S-deficient mice were protected from growth restriction and had improved alveolarization, decreased septal wall thickness, lower number of macrophages, and lower protein concentration in bronchoalveolar lavage fluid. alpha-Smooth muscle actin-expressing myofibroblasts accounted for at least some of the increased interstitial cellularity in hyperoxia-exposed mouse lungs and were significantly less in cat S-deficient lungs. Lung hydroxyproline content was increased in hyperoxia-exposed wild-type, but not in cat S-deficient lungs. Desmosine content was significantly reduced in both genotypes with hyperoxia.

CONCLUSIONS

Cathepsin S deficiency improves alveolarization, and attenuates macrophage influx and fibroproliferative changes in hyperoxia-induced neonatal mouse lung injury.

Transgenic and gene-targeted mice as models for chronic obstructive pulmonary disease

Animal models play an important role in the understanding of the pathogenesis of chronic obstructive pulmonary disease (COPD). The applicability of findings to human COPD depends upon several factors, including the disease model, and similarities in mouse structure and function between species. There are many examples in the literature of transgenic mice that have contributed to the understanding of COPD. Several studies demonstrate the complexity of inflammatory networks and how unexpected findings in animal models have led to the search for new potential mediators in human disease. Gene-targeting studies into alpha(1)-antitrypsin (alpha(1)-AT) and emphysema in mice have demonstrated that the genetic locus for alpha(1)-AT in mice is very complex and that the loss of one gene is lethal in embryo lung development. This underlines the differences between mice and humans that limit the ability to translate between systems in some instances. Gene targeting has also highlighted complex roles for transforming growth factor-beta in COPD and has been used to determine important molecules and pathways in COPD. Both transgenic and gene-targeted models suffer limitations and their applicability to human chronic obstructive pulmonary disease may be dependant on several factors, some of which are still being learnt. The more that is known about similarities and differences, the better the knowledge will be that is gained to develop for chronic obstructive pulmonary disease.

K-ras activation generates an inflammatory response in lung tumors

Activating mutations in K-ras are one of the most common genetic alterations in human lung cancer. To dissect the role of K-ras activation in bronchial epithelial cells during lung tumorigenesis, we created a model of lung adenocarcinoma by generating a conditional mutant mouse with both Clara cell secretory protein (CC10)-Cre recombinase and the Lox-Stop-Lox K-ras(G12D) alleles. The activation of K-ras mutant allele in CC10 positive cells resulted in a progressive phenotype characterized by cellular atypia, adenoma and ultimately adenocarcinoma. Surprisingly, K-ras activation in the bronchiolar epithelium is associated with a robust inflammatory response characterized by an abundant infiltration of alveolar macrophages and neutrophils. These mice displayed early mortality in the setting of this pulmonary inflammatory response with a median survival of 8 weeks. Bronchoalveolar lavage fluid from these mutant mice contained the MIP-2, KC, MCP-1 and LIX chemokines that increased significantly with age. Cell lines derived from these tumors directly produced MIP-2, LIX and KC. This model demonstrates that K-ras activation in the lung induces the elaboration of inflammatory chemokines and provides an excellent means to further study the complex interactions between inflammatory cells, chemokines and tumor progression.

Analysis of the inflammatory response induced by rhMMP-12 catalytic domain instilled in mouse airways

Macrophage elastase (MMP-12) is a metalloproteinase able to degrade extracellular matrix components such as elastin. As many MMPs, MMP-12 is involved in acute and chronic lung injury. However, its role in the inflammatory process of the lung parenchyma is not clearly understood. In this study, we have investigated the effects of airway instillation of rhMMP-12 on inflammatory cell recruitment, cytokine release and gelatinase expression in bronchoalveolar lavage fluid (BALF) or in lung homogenate supernatants in mice. Numbers of total and individual cell types were examined in BALF during the first 72 h following rhMMP-12 instillation. A marked recruitment of neutrophils was observed with a maximum increase at 18 h. This cellular recruitment was associated with a very transient increase in IL-6, TNF-alpha MIP-1alpha, MCP-1 and KC levels and gelatinase expression in BALF and in lung homogenate supernatants. From days 4 to 15, performing the same analyses, we observed an important and stable recruitment of macrophages in BALF in absence of the other studied inflammatory markers. These results demonstrate that rhMMP-12 itself is able to induce an early inflammatory response characterized by neutrophil infiltration, cytokine release and gelatinase activation followed by a later response composed mainly of macrophage recruitment.

Increase in macrophage elastase (MMP-12) in lungs from patients with chronic obstructive pulmonary disease

OBJECTIVE AND DESIGN

Chronic obstructive pulmonary disease (COPD) is characterized by an inflammatory process and airway remodeling involving matrix metalloproteinases (MMPs). Thus, we analyzed the expression and release of MMP-12 (macrophage metalloelastase) in bronchoalveolar lavage (BAL) and lung tissue from COPD patients and control subjects.

METHODS

Immunocytochemistry and immunochemistry were performed to analyze the expression of MMP-12 in BAL cells and bronchial biopsies. Western blotting was used for the evaluation of MMP-12 in BAL fluids.

RESULTS

The number of MMP-12 expressing macrophages together with the staining intensity was higher in BAL samples from COPD patients than in controls subjects. Similar results were noted in bronchial biopsies with higher MMP-12 expression in COPD subjects than in controls. Enhanced MMP-12 level was also observed in BAL fluids from patient with COPD in comparison to control subjects.

CONCLUSION

This study demonstrated that COPD patients produce greater quantities of MMP-12 than controls, which may be a critical step in the pathogenesis of COPD and emphysema.

Chronic obstructive pulmonary disease: molecular and cellular mechanisms

Chronic obstructive pulmonary disease is a leading cause of death and disability, but has only recently been extensively explored from a cellular and molecular perspective. There is a chronic inflammation that leads to fixed narrowing of small airways and alveolar wall destruction (emphysema). This is characterised by increased numbers of alveolar macrophages, neutrophils and cytotoxic T-lymphocytes, and the release of multiple inflammatory mediators (lipids, chemokines, cytokines, growth factors). A high level of oxidative stress may amplify this inflammation. There is also increased elastolysis and evidence for involvement of several elastolytic enzymes, including serine proteases, cathepsins and matrix metalloproteinases. The inflammation and proteolysis in chronic obstructive pulmonary disease is an amplification of the normal inflammatory response to cigarette smoke. This inflammation, in marked contrast to asthma, appears to be resistant to corticosteroids, prompting a search for novel anti-inflammatory therapies that may prevent the relentless progression of the disease.

Chronic obstructive pulmonary disease * 3: Experimental animal models of pulmonary emphysema

The use of genetically manipulated mice together with traditional animal studies are steadily increasing our knowledge of the factors important in determining alveolar formation and destruction in emphysema. A review of the animal models used to study emphysema is presented.

Proteinases in chronic obstructive pulmonary disease

Chronic obstructive pulmonary disease (COPD) is a major health problem worldwide, and we have little specific therapy to offer these patients. One potential strategy to limit loss of lung function in COPD would be to inhibit matrix-degrading proteinases. Several serine proteinases and matrix metalloproteinases are expressed in association with COPD in humans. Application of gene-targeted macrophage elastase and neutrophil elastase to a mouse model of cigarette-smoke-induced emphysema has uncovered roles for these proteinases in airspace enlargement, and has identified many interactions between these proteolytic systems.

Matrix metalloproteinases in lung biology

Despite much information on their catalytic properties and gene regulation, we actually know very little of what matrix metalloproteinases (MMPs) do in tissues. The catalytic activity of these enzymes has been implicated to function in normal lung biology by participating in branching morphogenesis, homeostasis, and repair, among other events. Overexpression of MMPs, however, has also been blamed for much of the tissue destruction associated with lung inflammation and disease. Beyond their role in the turnover and degradation of extracellular matrix proteins, MMPs also process, activate, and deactivate a variety of soluble factors, and seldom is it readily apparent by presence alone if a specific proteinase in an inflammatory setting is contributing to a reparative or disease process. An important goal of MMP research will be to identify the actual substrates upon which specific enzymes act. This information, in turn, will lead to a clearer understanding of how these extracellular proteinases function in lung development, repair, and disease.

The serpin MNEI inhibits elastase-like and chymotrypsin-like serine proteases through efficient reactions at two active sites

MNEI (monocyte/neutrophil elastase inhibitor) is a 42 kDa serpin superfamily protein characterized initially as a fast-acting inhibitor of neutrophil elastase. Here we show that MNEI has a broader specificity, efficiently inhibiting proteases with elastase- and chymotrypsin-like specificities. Reaction of MNEI with neutrophil proteinase-3, an elastase-like protease, and porcine pancreatic elastase demonstrated rapid inhibition rate constants >10(7) M(-1) s(-1), similar to that observed for neutrophil elastase. Reactions of MNEI with chymotrypsin-like proteases were also rapid: cathepsin G from neutrophils (>10(6) M(-1) s(-1)), mast cell chymase (>10(5) M(-1) s(-1)), chymotrypsin (>10(6) M(-1) s(-1)), and prostate-specific antigen (PSA), which had the slowest rate constant at approximately 10(4) M(-1) s(-1). Inhibition of trypsin-like (plasmin, granzyme A, and thrombin) and caspase-like (granzyme B) serine proteases was not observed or highly inefficient (trypsin), nor was inhibition of proteases from the cysteine (caspase-1 and caspase-3) and metalloprotease (macrophage elastase, MMP-12) families. The stoichiometry of inhibition for all inhibitory reactions was near 1, and inhibitory complexes were resistant to dissociation by SDS, further indicating the specificity of MNEI for elastase- and chymotrypsin-like proteases. Determination of the reactive site of MNEI by N-terminal sequencing and mass analysis of reaction products identified two reactive sites, each with a different specificity. Cys(344), which corresponds to Met(358), the P(1) site of alpha1-antitrypsin, was the inhibitory site for elastase-like proteases and PSA, while the preceding residue, Phe(343), was the inhibitory site for chymotrypsin-like proteases. This study demonstrates that MNEI has two functional reactive sites corresponding to the predicted P(1) and P(2) positions of the reactive center loop. The data suggest that MNEI plays a regulatory role at extravascular sites to limit inflammatory damage due to proteases of cellular origin.

Inhibition of matrix metalloproteinases blocks lethal hepatitis and apoptosis induced by tumor necrosis factor and allows safe antitumor therapy

Acute and fulminant liver failure induced by viral hepatitis, alcohol or other hepatotoxic drugs, are associated with tumor necrosis factor (TNF) production. In a mouse model of lethal hepatitis induced by TNF, apoptosis and necrosis of hepatocytes, but also lethality, hypothermia and influx of leukocytes into the liver, are prevented by a broad-spectrum matrix metalloproteinase (MMP) inhibitor, BB-94. Mice deficient in MMP-2, MMP-3 or MMP-9 had lower levels of apoptosis and necrosis of hepatocytes, and better survival. We found induction of MMP-9 activity and fibronectin degradation. Our findings suggest that several MMPs play a critical role in acute, fulminant hepatitis by degrading the extracellular matrix and allowing massive leukocyte influx in the liver. BB-94 also prevented lethality in TNF/interferon-gamma therapy in tumor-bearing mice. A broad-spectrum MMP inhibitor may be potentially useful for the treatment of patients with acute and perhaps chronic liver failure, and in cancer therapies using inflammatory cytokines.

Induction of macrophage matrix metalloproteinase biosynthesis by surfactant protein D

Recent studies strongly suggest that surfactant protein D (SP-D) plays important roles in pulmonary host defense and the regulation of immune and inflammatory reactions in the lung. Although SP-D can bind to alveolar macrophages and can elicit their chemotaxis, relatively little is known about the direct cellular consequences of SP-D on the function of these cells. Because matrix metalloproteinases (MMPs) are synthesized in increased amounts in response to various proinflammatory stimuli, we investigated the capacity of SP-D to modulate the production of MMPs by freshly isolated human alveolar macrophages. Unexpectedly we found that recombinant rat SP-D dodecamers selectively induce the biosynthesis of collagenase-1 (MMP-1), stromelysin (MMP-3), and macrophage elastase (MMP-12) without significantly increasing the production of tumor necrosis factor alpha and interleukin-1beta. SP-D did not alter the production of these MMPs by fibroblasts. Phosphatidylinositol, a surfactant-associated ligand that interacts with the carboxyl-terminal neck and carbohydrate recognition domains of SP-D, inhibited the SP-D-dependent increase in MMP biosynthesis. A trimeric, recombinant protein consisting of only the neck and carbohydrate recognition domain did not augment metalloproteinase production, suggesting that the stimulatory effect on MMP production depends on an appropriate spatial presentation of trimeric lectin domains. Although SP-D dodecamers can selectively augment metalloproteinase activity in vitro, this effect may be competitively inhibited by tissue inhibitors of metalloproteinases or surfactant-associated ligands in vivo.

Involvement of a serine protease, but not of neutrophil elastase, in tumor necrosis factor-induced lethal hepatitis and induction of platelet-activating factor

BACKGROUND/AIMS

Tumor necrosis factor (TNF) plays an essential role in several types of acute and chronic hepatitis. Our aims in the present study were to elucidate the mechanism by which TNF leads to acute lethal hepatitis, thereby focusing on the role of serine proteases and platelet-activating factor (PAF).

METHODS

All experiments were performed in a model of acute hepatitis, induced by TNF in combination with D-(+)-galactosamine (GalN). Neutrophil elastase (NE)-deficient mice, generated by gene targeting were used in the studies.

RESULTS

We found that a serine protease plays an essential mediating role in the in vivo TNF effect as alpha1-antitrypsin (alpha1-AT), soybean trypsin inhibitor (STI) and turkey trypsin inhibitor (TTI), confer complete protection. alpha1-AT and TTI, but not STI, reduce PAF blood levels, induced by TNF/GalN, which is compatible with an elastase-like serine protease involvement in PAF synthesis. In our search for relevant serine proteases we believed that NE was an excellent candidate protease. However, we found that TNF/GalN-induced lethality is not attenuated in mice deficient in NE.

CONCLUSIONS

The data suggest that TNF-induced lethal hepatitis is accompanied by increases in circulating PAF and plasma clotting time, and mediated by a serine protease, but not by NE.

Deficiency of urokinase-type plasminogen activator-mediated plasmin generation impairs vascular remodeling during hypoxia-induced pulmonary hypertension in mice

BACKGROUND

Chronic hypoxia results in the development of pulmonary hypertension and subsequent right heart failure. A role of the plasminogen system in the pathogenesis of pulmonary hypertension and pulmonary vascular remodeling has been suggested.

METHODS AND RESULTS

Mice with targeted deficiency of the gene encoding tissue-type plasminogen activator (t-PA(-/-)), urokinase-type plasminogen activator (u-PA(-/-)), u-PA receptor (u-PAR(-/-)), or plasminogen (plg(-/-)) were subjected to hypoxic conditions. Hypoxia caused a significant 2.5-fold rise in right ventricular pressure in wild-type mice. Deficiency of u-PA or plasminogen prevented this increase in right ventricular pressure, t-PA(-/-) mice showed changes that were fully comparable with wild-type mice, and u-PAR(-/-) mice showed a partial response. Hypoxia induced an increase in smooth muscle cells within pulmonary arterial walls and a vascular rarefaction in the lungs of wild-type but not of u-PA(-/-) or plg(-/-) mice. Elastic lamina fragmentation, observed in hypoxic wild-type but not in u-PA or plasminogen-deficient mice, suggested that proliferation of vascular smooth muscle cells was dependent on u-PA-mediated elastic membrane degradation. Hypoxia-induced right ventricular remodeling in wild-type mice, characterized by cardiomyocyte hypertrophy and increased collagen contents, was not seen in u-PA(-/-) and plg(-/-) mice.

CONCLUSIONS

Loss of the u-PA or plasminogen gene protects against the development of hypoxia-induced pulmonary hypertension and pulmonary vascular remodeling. These observations point to an essential role of u-PA-mediated plasmin generation in the adaptive response to chronic hypoxia and the occurrence of hypoxic pulmonary vascular disease.

Proteinase-activated receptor-1 regulation of macrophage elastase (MMP-12) secretion by serine proteinases

The serine proteinases plasmin and thrombin convert proenzyme matrix metalloproteinases (MMPs) into catalytically active forms. In addition, we demonstrate that plasmin(ogen) and thrombin induce a significant increase in secretion of activated murine macrophage elastase (MMP-12) protein. Active serine protease is responsible for induction, as demonstrated by the absence of MMP-12 induction in plasminogen(Plg)-treated urokinase-type plasminogen activator-deficient macrophages. Since increased MMP-12 protein secretion was not accompanied by an increase in MMP-12 mRNA, we examined post-translational mechanisms. Protein synthesis was not required for early release of MMP-12 but was required for later secretion of activated enzyme. Immunofluorescent microscopy demonstrated basal expression in macrophages that increased following serine proteinase exposure. Inhibition of MMP-12 secretion by hirudin and pertussis toxin demonstrated a role for the thrombin G protein-coupled receptor (protease-activated receptor 1 (PAR-1)). PAR-1-activating peptides were able to induce MMP-12 release. Investigation of signal transduction pathways involved in this response demonstrate the requirement for protein kinase C, but not tyrosine kinase, activity. These data demonstrate that plasmin and thrombin regulate MMP-12 activity through distinct mechanisms: post-translational secretion of preformed MMP-12 protein, induction of protein secretion that is protein kinase C-mediated, and extracellular enzyme activation. Most importantly, we show that serine proteinase MMP-12 regulation in macrophages occurs via the protein kinase C-activating G protein-coupled receptor PAR-1.

Evolving concepts in the pathogenesis of chronic obstructive pulmonary disease

It is arguable that more biologic insight has been gained from the study of COPD than from any other pulmonary disorder. A vast knowledge of the biology of extracellular matrix proteins, proteinases, and proteinase inhibitors has largely stemmed from the elastase:anti-elastase hypothesis for the pathogenesis of emphysema. An equally compelling case could be made that interest in, and funding for, COPD research has been woeful, and investigators have made no significant medical breakthroughs in the treatment of this disorder, which, unfortunately, is becoming epidemic worldwide. Indeed, it cannot be argued that physicians have very little treatment to offer to the many patients with COPD. Humankind is rapidly approaching a time when all human genes will be sequenced, and genetic engineering will allow determination of the function of these proteins in vivo. Expression profiling and bioinformatics will allow clinicians to assess the spectrum of genes and proteins regulated in biologic processes, no longer limiting study to naïve candidate genes. These advances will allow investigators to decipher precise pathways of complex diseases, identify genetic and environmental interactions, and ultimately lead to specific (pre)diagnoses and rational treatment. Answers to the question as to why only a subset of smokers develop COPD will enhance the understanding of the disease process. Fortunately, there has been a resurgence of interest in COPD, led largely by the pharmaceutical industry, which has discovered the potential of this unmet need. Consequently, these state-of-the-art scientific techniques are being directly applied to COPD, lending hope for the future. Of even greater importance, the tide seems to be turning on the cigarette industry. Although difficult to imagine, perhaps cigarettes will disappear in this lifetime or at least the next generation won't be fooled by this deadly habit! Well ... the rational therapy thing could work.

Inducible targeting of IL-13 to the adult lung causes matrix metalloproteinase- and cathepsin-dependent emphysema

Cigarette smoke exposure is the major cause of chronic obstructive pulmonary disease (COPD). However, only a minority of smokers develop significant COPD, and patients with asthma or asthma-like airway hyperresponsiveness or eosinophilia experience accelerated loss of lung function after cigarette smoke exposure. Pulmonary inflammation is a characteristic feature of lungs from patients with COPD. Surprisingly, the mediators of this inflammation and their contributions to the pathogenesis and varied natural history of COPD are not well defined. Here we show that IL-13, a critical cytokine in asthma, causes emphysema with enhanced lung volumes and compliance, mucus metaplasia, and inflammation, when inducibly overexpressed in the adult murine lung. MMP-2, -9, -12, -13, and -14 and cathepsins B, S, L, H, and K were induced by IL-13 in this setting. In addition, treatment with MMP or cysteine proteinase antagonists significantly decreased the emphysema and inflammation, but not the mucus in these animals. These studies demonstrate that IL-13 is a potent stimulator of MMP and cathepsin-based proteolytic pathways in the lung. They also demonstrate that IL-13 causes emphysema via a MMP- and cathepsin-dependent mechanism(s) and highlight common mechanisms that may underlie COPD and asthma.

Matrix metalloproteinases cleave tissue factor pathway inhibitor. Effects on coagulation

The capacity of inflammatory cell-derived matrix metalloproteinases (MMPs) to cleave tissue factor pathway inhibitor (TFPI) and alter its activity was investigated. MMP-7 (matrilysin) rapidly cleaved TFPI to a major 35-kDa product. In contrast, MMP-1 (collagenase-1), MMP-9 (gelatinase B), and MMP-12 (macrophage elastase) cleaved TFPI into several fragments including the 35-kDa band. However, rates of cleavage were most rapid for MMP-7 and MMP-9. NH(2)-terminal amino acid sequencing revealed that MMP-12 cleaved TFPI at Lys(20)-Leu(21)(close to Kunitz I domain and producing a 35-kDa band), Arg(83)-Ile(84) (between Kunitz I and II domains), and Ser(174)-Thr(175) (between Kunitz II and III domains). MMP-7 and MMP-9 cleaved TFPI at Lys(20)-Leu(21) with additional COOH-terminal processing. These MMPs did not cleave tissue factor (TF), factor VII, and factor Xa. Proteolytic cleavage by MMP-1, MMP-7, MMP-9, and MMP-12 resulted in considerable loss of TFPI activity. These observations indicate specific cleavage of TFPI by MMPs, which broadens their substrate profile. Co-localization of MMPs, TF, and TFPI in atherosclerotic tissues suggests that release of MMPs from inflammatory cell leukocytes may effect TF-mediated coagulation.

Contribution of monocytes/macrophages to compensatory neovascularization: the drilling of metalloelastase-positive tunnels in ischemic myocardium

In a transgenic model of ischemic cardiomyopathy in which monocytes are attracted to the myocardium by the targeted overexpression of monocyte chemoattractant protein-1 (MCP-1), we have observed the presence of endothelial NO synthase and platelet endothelial cell adhesion molecule-1-negative tunnels, occasionally containing blood-derived cells, that probe the cardiac tissue. Immunohistochemical data show that monocytes/macrophages (MCs/Mphs) drill tunnels using the broad-spectrum mouse macrophage metalloelastase. 5-Bromo-2'-deoxyuridine incorporation and neo-endothelial markers present in the microvasculature of MCP-1 mouse hearts suggest an active angiogenic process. Further studies will be required to establish that the MC-/Mph-drilled tunnels evolve to become capillaries, connected to the existing vessels and colonized by circulating endothelial cell progenitors. This possibility is supported by the availability of these cells, which is demonstrated by cell tagging with beta-galactosidase placed under an active endothelial Tie-2 promoter. This phenomenon might represent another mechanism, in addition to the secretion of the angiogenic factors, by which MCs/MPhs may participate in the elaboration of new blood vessels in adult tissues.

The serpin alpha1-proteinase inhibitor is a critical substrate for gelatinase B/MMP-9 in vivo

We have identified the key protein substrate of gelatinase B/MMP-9 (GB) that is cleaved in vivo during dermal-epidermal separation triggered by antibodies to the hemidesmosomal protein BP180 (collagen XVII, BPAG2). Mice deficient in either GB or neutrophil elastase (NE) are resistant to blister formation in response to these antibodies in a mouse model of the autoimmune disease bullous pemphigoid. Disease develops upon complementation of GB -/- mice with NE -/- neutrophils or NE -/- mice with GB -/- neutrophils. Only NE degrades BP180 and produces dermal-epidermal separation in vivo and in culture. Instead, GB acts upstream to regulates NE activity by inactivating alpha1-proteinase inhibitor (alpha1-PI). Excess NE produces lesions in GB -/- mice without cleaving alpha1-PI. Excess alpha1-PI phenocopies GB and NE deficiency in wild-type mice.

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.

Ciliogenesis and left-right axis defects in forkhead factor HFH-4-null mice

Cilia have been classified as sensory or motile types on the basis of functional and structural characteristics; however, factors important for regulation of assembly of different cilia types are not well understood. Hepatocyte nuclear factor-3/forkhead homologue 4 (HFH-4) is a winged helix/forkhead transcription factor expressed in ciliated cells of the respiratory tract, oviduct, and ependyma in late development through adulthood. Targeted deletion of the Hfh4 gene resulted in defective ciliogenesis in airway epithelial cells and randomized left-right asymmetry so that half the mice had situs inversus. In HFH-4-null mice, classic motile type cilia with a 9 + 2 microtubule ultrastructure were absent in epithelial cells, including those in the airways. In other organs, sensory cilia with a 9 + 0 microtubule pattern, such as those on olfactory neuroepithelial cells, were present. Ultrastructural analysis of mutant cells with absent 9 + 2 cilia demonstrated that defective ciliogenesis was due to abnormal centriole migration and/or apical membrane docking, suggesting that HFH-4 functions to direct basal body positioning or anchoring. Evaluation of wild-type embryos at gestational days 7.0 to 7.5 revealed Hfh4 expression in embryonic node cells that have monocilium, consistent with a function for this factor at the node in early determination of left- right axis. Analysis of the node of HFH-4 mutant embryos revealed that, in contrast to absent airway cilia, node cilia were present. These observations indicate that there are independent regulatory pathways for node ciliogenesis compared with 9 + 2 type ciliogenesis in airways, and support a central role for HFH-4 in ciliogenesis and left-right axis formation.

Effect of partial liquid ventilation on pulmonary vascular permeability and edema after experimental acute lung injury

We evaluated the effects of partial liquid ventilation (PLV) with two different dosages of the perfluorocarbon LiquiVent (perflubron) on pulmonary vascular permeability and edema formation after oleic acid (OA)-induced acute lung injury in dogs. We used imaging with positron emission tomography to measure fractional pulmonary blood flow, lung water concentration (LWC), and the pulmonary transcapillary escape rate (PTCER) of (68)Ga-labeled transferrin at 5 and 21 h after lung injury in five dogs undergoing conventional mechanical ventilation (CMV), five dogs undergoing low-dose PLV (perflubron at 10 ml/kg), and four dogs undergoing high dose PLV (perflubron at 30 ml/kg). A positive end-expiratory pressure of 7.5 cm H(2)O was used in all dogs. After OA (0.08 ml/kg)- induced lung injury, there were no significant differences or trends for PTCER or LWC at any time when the PLV groups were compared with the CMV group. However, lung tissue myeloperoxidase activity was significantly lower in the combined PLV group than in the CMV group (p = 0.016). We conclude that after OA-induced lung injury, the addition of PLV to CMV does not directly attenuate pulmonary vascular leak or lung water accumulation. Rather, the benefits of such treatment may be due to modifications of the inflammatory response.

Developmental expression of latent transforming growth factor beta binding protein 2 and its requirement early in mouse development

Latent transforming growth factor beta (TGF-beta) binding protein 2 (LTBP-2) is an integral component of elastin-containing microfibrils. We studied the expression of LTBP-2 in the developing mouse and rat by in situ hybridization, using tropoelastin expression as a marker of tissues participating in elastic fiber formation. LTBP-2 colocalized with tropoelastin within the perichondrium, lung, dermis, large arterial vessels, epicardium, pericardium, and heart valves at various stages of rodent embryonic development. Both LTBP-2 and tropoelastin expression were seen throughout the lung parenchyma and within the cortex of the spleen in the young adult mouse. In the testes, LTBP-2 expression was seen within lumenal cells of the epididymis in the absence of tropoelastin. Collectively, these results imply that LTBP-2 plays a structural role within elastic fibers in most cases. To investigate its importance in development, mice with a targeted disruption of the Ltbp2 gene were generated. Ltbp2(-/-) mice die between embryonic day 3.5 (E3.5) and E6.5. LTBP-2 expression was not detected by in situ hybridization in E6.5 embryos but was detected in E3.5 blastocysts by reverse transcription-PCR. These results are not consistent with the phenotypes of TGF-beta knockout mice or mice with knockouts of other elastic fiber proteins, implying that LTBP-2 performs a yet undiscovered function in early development, perhaps in implantation.

Targeted gene disruption of matrix metalloproteinase-9 (gelatinase B) suppresses development of experimental abdominal aortic aneurysms

Abdominal aortic aneurysms represent a life-threatening condition characterized by chronic inflammation, destructive remodeling of the extracellular matrix, and increased local expression of matrix metalloproteinases (MMPs). Both 92-kD gelatinase (MMP-9) and macrophage elastase (MMP-12) have been implicated in this disease, but it is not known if either is necessary in aneurysmal degeneration. We show here that transient elastase perfusion of the mouse aorta results in delayed aneurysm development that is temporally associated with transmural mononuclear inflammation, increased local production of several elastolytic MMPs, and progressive destruction of the elastic lamellae. Elastase-induced aneurysmal degeneration was suppressed by treatment with a nonselective MMP inhibitor (doxycycline) and by targeted gene disruption of MMP-9, but not by isolated deficiency of MMP-12. Bone marrow transplantation from wild-type mice prevented the aneurysm-resistant phenotype in MMP-9-deficient animals, and wild-type mice acquired aneurysm resistance after transplantation from MMP-9-deficient donors. These results demonstrate that inflammatory cell expression of MMP-9 plays a critical role in an experimental model of aortic aneurysm disease, suggesting that therapeutic strategies targeting MMP-9 may limit the growth of small abdominal aortic aneurysms.

Expression of human macrophage metalloelastase (MMP-12) by tumor cells in skin cancer

Matrix metalloproteinases play an essential role in tumor growth and invasion. Different matrix metalloproteinases are often expressed in cancers with distinct patterns. To investigate the role of human macrophage metalloelastase (MMP-12) in epidermal tumors, we studied human macrophage metalloelastase mRNA and protein expression in malignant squamous cell and basal cell carcinomas, and in premalignant Bowen's disease. Human macrophage metalloelastase was detected in 11 of 17 squamous cell carcinomas in epithelial cancer cells, whereas macrophages were positive in 15 of 17 samples. In basal cell carcinomas, human macrophage metalloelastase was more often found in macrophages (seven of 19) than in cancer cells (four of 19). Human macrophage metalloelastase mRNA was also detected in three cell lines derived from squamous cell carcinomas of the head and neck and in transformed HaCaT cells, whereas premalignant tumors and primary keratinocytes were negative for human macrophage metalloelastase mRNA. Western analysis revealed human macrophage metalloelastase protein in squamous cell carcinoma cells. Our results show that human macrophage metalloelastase can be expressed in vivo and in vitro by transformed epithelial cells and indicate that the level of human macrophage metalloelastase expression correlates with epithelial dedifferentiation and histologic aggressiveness.

The effect of respiratory therapist-initiated treatment protocols on patient outcomes and resource utilization

CONTEXT

Physicians frequently prescribe respiratory treatments to hospitalized patients, but the influence of such treatments on clinical outcomes is difficult to assess.

OBJECTIVE

To compare the clinical outcomes of patients receiving respiratory treatments managed by respiratory care practitioner (RCP)-directed treatment protocols or physician-directed orders.

DESIGN

A single center, quasi-randomized, clinical study.

SETTING

Three internal medicine firms from an urban teaching hospital.

PATIENTS

Six hundred ninety-four consecutive hospitalized non-ICU patients ordered to receive respiratory treatments.

MAIN OUTCOME MEASURES

Discordant respiratory care orders, respiratory care charges, hospital length of stay, and patient-specific complications. Discordant orders were defined as written orders for respiratory treatments that were not clinically indicated as well as orders omitting treatments that were clinically indicated according to protocol-based treatment algorithms.

RESULTS

Firm A patients (n = 239) received RCP-directed treatments and had a statistically lower rate of discordant respiratory care orders (24.3%) as compared with patients receiving physician-directed treatments in firms B (n = 205; 58.5%) and C (n = 250; 56.8%; p < 0.001). No statistically significant differences in patient complications were observed. The average number of respiratory treatments and respiratory care charges were statistically less for firm A patients (10.7 +/- 13.7 treatments; $868 +/- 1,519) as compared with patients in firms B (12.4 +/- 12.7 treatments, $1,124 +/- 1,339) and C (12.3 +/- 13.4 treatments, $1, 054 +/- 1,346; p = 0.009 [treatments] and p < 0.001 [respiratory care charges]).

CONCLUSIONS

Respiratory care managed by RCP-directed treatment protocols for non-ICU patients is safe and showed greater agreement with institutional treatment algorithms as compared with physician-directed respiratory care. Additionally, the overall utilization of respiratory treatments was significantly less among patients receiving RCP-directed respiratory care.

Substance P and neurokinin-1 receptor expression by intrinsic airway neurons in the rat

Tachykinins and their receptors are involved in the amplification of inflammation in the airways. We analyzed the expression of preprotachykinin-A (PPT-A) and neurokinin-1 (NK-1) receptor genes by intrinsic airway neurons in the rat. We also tested the hypothesis that PPT-A-encoded peptides released by these neurons fulfill the requisite role of substance P in immune complex injury of the lungs. We found that ganglion neurons in intact and denervated airways or in primary culture coexpress PPT-A and NK-1 receptor mRNAs and their protein products. Denervated ganglia from tracheal xenografts (nu/nu mice) or syngeneic lung grafts had increased PPT-A mRNA contents, suggesting preganglionic regulation. Formation of immune complexes in the airways induced comparable inflammatory injuries in syngeneic lung grafts, which lack peptidergic sensory fibers, and control lungs. The injury was attenuated in both cases by pretreatment with the NK-1 receptor antagonist LY-306740. We conclude that tachykinins released by ganglia act as a paracrine or autocrine signal in the airways and may contribute to NK-1 receptor-mediated amplification of immune injury in the lungs.

A critical role for neutrophil elastase in experimental bullous pemphigoid

Bullous pemphigoid (BP) is an autoimmune skin disease characterized by subepidermal blisters and autoantibodies against 2 hemidesmosome-associated proteins, BP180 and BP230. The immunopathologic features of BP can be reproduced in mice by passive transfer of anti-BP180 antibodies. Lesion formation in this animal model depends upon complement activation and neutrophil recruitment. In the present study, we investigated the role of neutrophil elastase (NE) in antibody-induced blister formation in experimental BP. Abnormally high levels of caseinolytic activity, consistent with NE, were detected in extracts of lesional skin and blister fluid of mice injected with anti-BP180 IgG. The pathogenic anti-BP180 IgG failed to induce subepidermal blistering in NE-null (NE(-/-)) mutant mice. NE(-/-) mice reconstituted with neutrophils from wild-type mice became susceptible to experimental BP. Wild-type mice given NE inhibitors (alpha1-proteinase inhibitor and Me-O-Suc-Ala-Ala-Pro-Val-CH(2)Cl), but not mice given cathepsin G/chymase inhibitors (alpha1-antichymotrypsin or Z-Gly-Leu-Phe-CH(2)Cl), were resistant to the pathogenic activity of anti-BP180 antibodies. Incubation of murine skin with NE induced BP-like epidermal-dermal detachment. Finally, NE cleaved BP180 in vitro and in vivo. These results implicate NE directly in the dermal-epidermal cleavage induced by anti-BP180 antibodies in the experimental BP model.

Normal neutrophil function in cathepsin G-deficient mice

Cathepsin G is a neutral serine protease that is highly expressed at the promyelocyte stage of myeloid development. We have developed a homologous recombination strategy to create a loss-of-function mutation for murine cathepsin G. Bone marrow derived from mice homozygous for this mutation had no detectable cathepsin G protein or activity, indicating that no other protease in bone marrow cells has the same specificity. Hematopoiesis in cathepsin G-/- mice is normal, and the mice have no overt abnormalities in blood clotting. Neutrophils derived from cathepsin G-/- mice have normal morphology and azurophil granule composition; these neutrophils also display normal phagocytosis and superoxide production and have normal chemotactic responses to C5a, fMLP, and interleukin-8. Although cathepsin G has previously shown to have broad spectrum antibiotic properties, challenges of mice with Staphylococcus aureus, Klebsiella pneumoniae, or Escherichia coli yielded survivals that were not different from those of wild-type animals. In sum, cathepsin G-/- neutrophils have no obvious defects in function; either cathepsin G is not required for any of these normal neutrophil functions or related azurophil granule proteases with different specificities (ie, neutrophil elastase, proteinase 3, azurocidin, and/or others) can substitute for it in vivo.

The macrophage in chronic obstructive pulmonary disease

Macrophages are the predominant defense cell in the normal lung and during conditions associated with chronic inflammation such as COPD. However, the role of the macrophage in the development of COPD has been controversial. Scientific evidence from a variety of sources is emerging that supports a primary role for the macrophage in regulating the inflammatory response and tissue destruction associated with COPD. The role of macrophage proteinases in the development of emphysema, a major component of COPD, will be discussed. Shapiro SD. The macrophage in chronic obstructive pulmonary disease.

Inhibition of plasminogen activators or matrix metalloproteinases prevents cardiac rupture but impairs therapeutic angiogenesis and causes cardiac failure

Cardiac rupture is a fatal complication of acute myocardial infarction lacking treatment. Here, acute myocardial infarction resulted in rupture in wild-type mice and in mice lacking tissue-type plasminogen activator, urokinase receptor, matrix metalloproteinase stromelysin-1 or metalloelastase. Instead, deficiency of urokinase-type plasminogen activator (u-PA-/-) completely protected against rupture, whereas lack of gelatinase-B partially protected against rupture. However, u-PA-/- mice showed impaired scar formation and infarct revascularization, even after treatment with vascular endothelial growth factor, and died of cardiac failure due to depressed contractility, arrhythmias and ischemia. Temporary administration of PA inhibitor-1 or the matrix metalloproteinase-inhibitor TIMP-1 completely protected wild-type mice against rupture but did not abort infarct healing, thus constituting a new approach to prevent cardiac rupture after acute myocardial infarction.

Monocyte inflammation augments acrolein-induced Muc5ac expression in mouse lung

Acrolein, an unsaturated aldehyde found in smog and tobacco smoke, can induce airway hyperreactivity, inflammation, and mucus hypersecretion. To determine whether changes in steady-state mucin gene expression (Muc2 and Muc5ac) are associated with inflammatory cell accumulation and neutrophil elastase activity, FVB/N mice were exposed to acrolein (3.0 parts/million; 6 h/day, 5 days/wk for 3 wk). The levels of Muc2 and Muc5ac mRNA were determined by RT-PCR, and the presence of Muc5ac protein was detected by immunohistochemistry. Total and differential cell counts were determined from bronchoalveolar lavage (BAL) fluid, and neutrophil elastase activity was measured in the BAL fluid supernatant. Lung Muc5ac mRNA was increased on days 12 and 19, and Muc5ac protein was detected in mucous granules and on the surface of the epithelium on day 19. Lung Muc2 mRNA was not detected at measurable levels in either control or exposed mice. Acrolein exposure caused a significant and persistent increase in macrophages and a rapid but transient increase in neutrophils in BAL fluid. Recoverable neutrophil elastase activity was not significantly altered at any time after acrolein exposure. To further examine the role of macrophage accumulation in mucin gene expression, additional strains of mice (including a strain genetically deficient in macrophage metalloelastase) were exposed to acrolein for 3 wk, and Muc5ac mRNA levels and macrophage accumulation were measured. The magnitude of macrophage accumulation coincided with increased Muc5ac mRNA levels, indicating that excessive macrophage accumulation augments acrolein-induced Muc5ac synthesis and secretion after repeated exposure. These findings support a role for chronic monocytic inflammation in the pathogenesis of mucus hypersecretion observed in chronic bronchitis.

Diverse roles of macrophage matrix metalloproteinases in tissue destruction and tumor growth

In the mouse, macrophage elastase is critical to macrophage proteolysis. The use of gene-targeting has uncovered both pathological roles, including destructive effects in aneurysm formation and emphysema, and physiological roles, such as tumor growth inhibition and regulation of inflammation. Translation of findings from mouse to human biology depends upon how well the disease models replicate the human conditions and the similarity of enzyme profile between species. We know that human MMP-12 is associated with these diseases, but as opposed to the mouse, other MMPs may also be of importance (MMP-9, and perhaps MMP-7, in particular). Our interpretation is that findings in mice reflect the critical role of macrophage proteolysis in these disease processes.