Monocyte NLRP3 inflammasome and interleukin-1ß activation modulated by alpha-1 antitrypsin therapy in deficient individuals.

INTRODUCTION: Altered complement component 3 (C3) activation in patients with alpha-1 antitrypsin (AAT) deficiency (AATD) has been reported. To understand the potential impact on course of inflammation, the aim of this study was to investigate whether C3d, a cleavage-product of C3, triggers interleukin (IL)-1ß secretion via activation of NOD-, LRR- and pyrin domain-containing protein 3 (NLRP3) inflammasome. The objective was to explore the effect of AAT augmentation therapy in patients with AATD on the C3d/complement receptor 3 (CR3) signalling axis of monocytes and on circulating pro-inflammatory markers. METHODS: Inflammatory mediators were detected in blood from patients with AATD (n=28) and patients with AATD receiving augmentation therapy (n=19). Inflammasome activation and IL-1ß secretion were measured in monocytes of patients with AATD, and following C3d stimulation in the presence or absence of CR3 or NLRP3 inhibitors. RESULTS: C3d acting via CR3 induces NLRP3 and pro-IL-1ß production, and through induction of endoplasmic reticulum (ER) stress and calcium flux, triggers caspase-1 activation and IL-1ß secretion. Treatment of individuals with AATD with AAT therapy results in decreased plasma levels of C3d (3.0±1.2 µg/mL vs 1.3±0.5 µg/mL respectively, p<0.0001) and IL-1ß (115.4±30 pg/mL vs 73.3±20 pg/mL, respectively, p<0.0001), with a 2.0-fold decrease in monocyte NLRP3 protein expression (p=0.0303), despite continued ER stress activation. DISCUSSION: These results provide strong insight into the mechanism of complement-driven inflammation associated with AATD. Although the described variance in C3d and NLRP3 activation decreased post AAT augmentation therapy, results demonstrate persistent C3d and monocyte ER stress, with implications for new therapeutics and clinical practice.

Evaluating Novel Protein Phosphatase 2A Activators as Therapeutics for Emphysema.

The activity of PP2A (protein phosphatase 2A), a serine-threonine phosphatase, is reduced by chronic cigarette smoke (SM) exposure and α-1 antitrypsin (AAT) deficiency, and chemical activation of PP2A reduces the loss of lung function in SM-exposed mice. However, the previously studied PP2A-activator tricyclic sulfonamide compound DBK-1154 has low stability to oxidative metabolism, resulting in fast clearance and low systemic exposure. Here we compare the utility of a new more stable PP2A activator, ATUX-792, versus DBK-1154 for the treatment of SM-induced emphysema. ATUX-792 was also tested in human bronchial epithelial cells and a mouse model of AAT deficiency, Serpina1a-e-knockout mice. Human bronchial epithelial cells were treated with ATUX-792 or DBK-1154, and cell viability, PP2A activity, and MAP (mitogen-activated protein) kinase phosphorylation status were examined. Wild-type mice received vehicle, DBK-1154, or ATUX-792 orally in the last 2 months of 4 months of SM exposure, and 8-month-old Serpina1a-e-knockout mice received ATUX-792 daily for 4 months. Forced oscillation and expiratory measurements and histology analysis were performed. Treatment with ATUX-792 or DBK-1154 resulted in PP2A activation, reduced MAP kinase phosphorylation, immune cell infiltration, reduced airspace enlargements, and preserved lung function. Using protein arrays and multiplex assays, PP2A activation was observed to reduce AAT-deficient and SM-induced release of CXCL5, CCL17, and CXCL16 into the airways, which coincided with reduced neutrophil lung infiltration. Our study indicates that suppression of the PP2A activity in two models of emphysema could be restored by next-generation PP2A activators to impact lung function.

Twenty-Four Month Results of Tack-Optimized Balloon Angioplasty Using the Tack Endovascular System in Below-the-Knee Arteries.

PURPOSE: To report 24 month safety and efficacy of the Tack Endovascular System for treatment of post-percutaneous transluminal angioplasty (PTA) infrapopliteal dissections in patients with critical limb-threatening ischemia (CLTI). MATERIALS AND METHODS: The Tack-Optimized Balloon Angioplasty (TOBA) II below-the-knee (BTK) study was a prospective, multicenter, single-arm evaluation of the Tack Endovascular system for post-PTA infrapopliteal dissection repair. Patients with Rutherford Clinical Category (RC) 3 to 5 and a post-PTA dissection(s) of the BTK arteries were enrolled. The 30 day primary safety endpoint was a composite of major adverse limb events (MALE) and all-cause perioperative death (POD). The primary effectiveness endpoint was a composite of MALE at 6 months and 30 day POD. Outcomes were assessed as observational endpoints at 24 months. RESULTS: Tack-Optimized Balloon Angioplasty II BTK enrolled 233 patients; all patients had a post-PTA dissection(s) and received ≥1 Tack implant (range, 1-16). Mean age was 74.4±10.0 years and 67.4% were men. Most patients had CLTI (RC 3: 16.3%; RC 4/5: 83.7%). Mean target lesion length was 80±49 mm. Moderate to severe calcium was present in 89 (35.8%) lesions and total occlusions were present in 118 (47.6%) lesions. Kaplan-Meier freedom from MALE at 24 months + POD at 30 days was 92.2% and 24 month freedom from clinically-driven target lesions revascularization was 73.6%. Kaplan-Meier target limb salvage was 95.7% and amputation-free survival was 75.4%. Improvements in functional status and quality of life were observed through 24 months. CONCLUSION: The TOBA II BTK study demonstrated sustained safety and efficacy through 24 months in patients treated for post-PTA dissection(s) of BTK lesions. CLINICAL TRIAL REGISTRATION: ClinicalTrials.gov identifier NCT02942966.

Primary results of the SAVAL randomized trial of a paclitaxel-eluting nitinol stent versus percutaneous transluminal angioplasty in infrapopliteal arteries.

BACKGROUND: Effective and durable options for infrapopliteal artery revascularization for patients with chronic limb-threatening ischemia (CLTI) are limited. METHODS: The SAVAL trial is a prospective, multicenter, randomized trial of patients with CLTI and infrapopliteal artery lesions with total lesion length ⩽ 140 mm, stenosis ⩾ 70%, and Rutherford category 4-5 assigned 2:1 to treatment with the SAVAL self-expandable paclitaxel drug-eluting stent (DES) or percutaneous transluminal angioplasty (PTA) with an uncoated balloon. The primary effectiveness endpoint was primary vessel patency (i.e., core lab-adjudicated duplex ultrasound-based flow at 12 months in the absence of clinically driven target lesion revascularization or surgical bypass of the target lesion). The primary safety endpoint was the 12-month major adverse event (MAE)-free rate; MAEs were defined as a composite of above-ankle index limb amputation, major reintervention, and 30-day mortality. The endpoints were prespecified for superiority (effectiveness) and noninferiority (safety) at a one-sided significance level of 2.5%. RESULTS: A total of 201 patients were enrolled and randomly assigned to treatment (N = 130 DES, N = 71 PTA). Target lesion length was 68.1 ± 35.2 mm for the DES group and 68.7 ± 49.2 mm for the PTA group, and 31.0% and 27.6% of patients, respectively, had occlusions. The 12-month primary patency rates were 68.0% for the DES group and 76.0% for the PTA group (Psuperiority = 0.8552). The MAE-free rates were 91.6% and 95.3%, respectively (Pnoninferiority = 0.0433). CONCLUSION: The SAVAL trial did not show benefit related to effectiveness and safety with the nitinol DES compared with PTA in infrapopliteal artery lesions up to 140 mm in length. Continued innovation to provide optimal treatments for CLTI is needed. (ClinicalTrials.gov Identifier: NCT03551496).

Respiratory Immune Responses during Infection and Pollution Inhalation.

The COVID-19 pandemic highlighted the importance of lung immune responses to pathogens and environmental factors [...].

The Relationship of Cholesterol Responses to Mitochondrial Dysfunction and Lung Inflammation in Chronic Obstructive Pulmonary Disease.

Hyperlipidemia is frequently reported in chronic obstructive pulmonary disease (COPD) patients and is linked to the progression of the disease and its comorbidities. Hypercholesterolemia leads to cholesterol accumulation in many cell types, especially immune cells, and some recent studies suggest that cholesterol impacts lung epithelial cells' inflammatory responses and mitochondrial responses. Several studies also indicate that targeting cholesterol responses with either statins or liver X receptor (LXR) agonists may be plausible means of improving pulmonary outcomes. Equally, cholesterol metabolism and signaling are linked to mitochondrial dysfunction and inflammation attributed to COPD progression. Here, we review the current literature focusing on the impact of cigarette smoke on cholesterol levels, cholesterol efflux, and the influence of cholesterol on immune and mitochondrial responses within the lungs.

Protein Phosphatase 2A as a Therapeutic Target in Pulmonary Diseases.

New disease targets and medicinal chemistry approaches are urgently needed to develop novel therapeutic strategies for treating pulmonary diseases. Emerging evidence suggests that reduced activity of protein phosphatase 2A (PP2A), a complex heterotrimeric enzyme that regulates dephosphorylation of serine and threonine residues from many proteins, is observed in multiple pulmonary diseases, including lung cancer, smoke-induced chronic obstructive pulmonary disease, alpha-1 antitrypsin deficiency, asthma, and idiopathic pulmonary fibrosis. Loss of PP2A responses is linked to many mechanisms associated with disease progressions, such as senescence, proliferation, inflammation, corticosteroid resistance, enhanced protease responses, and mRNA stability. Therefore, chemical restoration of PP2A may represent a novel treatment for these diseases. This review outlines the potential impact of reduced PP2A activity in pulmonary diseases, endogenous and exogenous inhibitors of PP2A, details the possible PP2A-dependent mechanisms observed in these conditions, and outlines potential therapeutic strategies for treatment. Substantial medicinal chemistry efforts are underway to develop therapeutics targeting PP2A activity. The development of specific activators of PP2A that selectively target PP2A holoenzymes could improve our understanding of the function of PP2A in pulmonary diseases. This may lead to the development of therapeutics for restoring normal PP2A responses within the lung.

The Society for Vascular Surgery clinical practice guidelines on popliteal artery aneurysms.

The Society for Vascular Surgery clinical practice guidelines on popliteal artery aneurysms (PAAs) leverage the work of a panel of experts chosen by the Society for Vascular Surgery to review the current world literature as it applies to PAAs to extract the most salient, evidence-based recommendations for the treatment of these patients. These guidelines focus on PAA screening, indications for intervention, choice of repair strategy, management of asymptomatic and symptomatic PAAs (including those presenting with acute limb ischemia), and follow-up of both untreated and treated PAAs. They offer long-awaited evidence-based recommendations for physicians taking care of these patients.

A systematic review of patient-reported outcome measures patients with chronic limb-threatening ischemia.

Chronic limb-threatening ischemia (CLTI) causes significant morbidity with profound negative effects on health-related quality of life. As the prevalence of peripheral artery disease and diabetes continue to rise in our aging population, the public health impact of CLTI has escalated. Patient-reported outcome measures (PROMs) have become common and important measures for clinical evaluation in both clinical care and research. PROMs are important for the measurement of clinical effectiveness and cost effectiveness and for shared decision-making on treatment options. However, the PROMs used to describe the experience of patients with CLTI are heterogeneous, incomplete, and lack specific applicability to the underlying disease processes and diverse populations. For example, certain PROMs exist for patients with extremity wounds, and other PROMs exist for patients with pain, and still others exist for patients with vascular disease. Despite this multiplicity of tools, no single PROM encompasses all of the components necessary to describe the experiences of patients with CLTI. This significant unmet need is evident from both published reports and contemporary large-scale clinical trials in the field. In this systematic review, we review the current use of PROMs for patients with CLTI in clinical practice and in research trials and highlight the gaps that need to be addressed to develop a unifying PROM instrument for CLTI.

Senescence: Pathogenic Driver in Chronic Obstructive Pulmonary Disease.

Chronic obstructive pulmonary disease (COPD) is recognized as a disease of accelerated lung aging. Over the past two decades, mounting evidence suggests an accumulation of senescent cells within the lungs of patients with COPD that contributes to dysregulated tissue repair and the secretion of multiple inflammatory proteins, termed the senescence-associated secretory phenotype (SASP). Cellular senescence in COPD is linked to telomere dysfunction, DNA damage, and oxidative stress. This review gives an overview of the mechanistic contributions and pathologic consequences of cellular senescence in COPD and discusses potential therapeutic approaches targeting senescence-associated signaling in COPD.

Mechanisms Linking COPD to Type 1 and 2 Diabetes Mellitus: Is There a Relationship between Diabetes and COPD?

Chronic obstructive pulmonary disease (COPD) patients frequently suffer from multiple comorbidities, resulting in poor outcomes for these patients. Diabetes is observed at a higher frequency in COPD patients than in the general population. Both type 1 and 2 diabetes mellitus are associated with pulmonary complications, and similar therapeutic strategies are proposed to treat these conditions. Epidemiological studies and disease models have increased our knowledge of these clinical associations. Several recent genome-wide association studies have identified positive genetic correlations between lung function and obesity, possibly due to alterations in genes linked to cell proliferation; embryo, skeletal, and tissue development; and regulation of gene expression. These studies suggest that genetic predisposition, in addition to weight gain, can influence lung function. Cigarette smoke exposure can also influence the differential methylation of CpG sites in genes linked to diabetes and COPD, and smoke-related single nucleotide polymorphisms are associated with resting heart rate and coronary artery disease. Despite the vast literature on clinical disease association, little direct mechanistic evidence is currently available demonstrating that either disease influences the progression of the other, but common pharmacological approaches could slow the progression of these diseases. Here, we review the clinical and scientific literature to discuss whether mechanisms beyond preexisting conditions, lifestyle, and weight gain contribute to the development of COPD associated with diabetes. Specifically, we outline environmental and genetic confounders linked with these diseases.

Balanced Wnt/Dickkopf-1 signaling by mesenchymal vascular progenitor cells in the microvascular niche maintains distal lung structure and function.

The well-described Wnt inhibitor Dickkopf-1 (DKK1) plays a role in angiogenesis as well as in regulation of growth factor signaling cascades in pulmonary remodeling associated with chronic lung diseases (CLDs) including emphysema and fibrosis. However, the specific mechanisms by which DKK1 influences mesenchymal vascular progenitor cells (MVPCs), microvascular endothelial cells (MVECs), and smooth muscle cells (SMCs) within the microvascular niche have not been elucidated. In this study, we show that knockdown of DKK1 in Abcg2pos lung mouse adult tissue resident MVPCs alters lung stiffness, parenchymal collagen deposition, microvessel muscularization and density as well as loss of tissue structure in response to hypoxia exposure. To complement the in vivo mouse modeling, we also identified cell- or disease-specific responses to DKK1, in primary lung chronic obstructive pulmonary disease (COPD) MVPCs, COPD MVECs, and SMCs, supporting a paradoxical disease-specific response of cells to well-characterized factors. Cell responses to DKK1 were dose dependent and correlated with varying expressions of the DKK1 receptor, CKAP4. These data demonstrate that DKK1 expression is necessary to maintain the microvascular niche whereas its effects are context specific. They also highlight DKK1 as a regulatory candidate to understand the role of Wnt and DKK1 signaling between cells of the microvascular niche during tissue homeostasis and during the development of chronic lung diseases.

Six-month pivotal results of tack optimized balloon angioplasty using the Tack Endovascular System in below-the-knee arteries.

OBJECTIVE: No vascular implant is commercially available in the United States to treat post-angioplasty dissections in below-the-knee (BTK) arteries. The Tack Endovascular System (Intact Vascular, Wayne, Pa) is purpose-built to repair postpercutaneous transluminal angioplasty (PTA) BTK dissections. A trial was conducted to investigate the safety and efficacy of the first-of-a-kind implantable BTK device to treat post-PTA dissections in the setting of critical limb ischemia. METHODS: The present prospective, single-arm, multicenter study evaluated the Tack Endovascular System for treating post-PTA dissections in the mid/distal popliteal, tibial, and peroneal arteries. The primary safety endpoint was major adverse limb events (MALE) plus perioperative death (POD), assessed at 30 days after the index procedure. The primary efficacy endpoint was a composite of MALE at 6 months and POD. The unpowered secondary endpoint was primary patency at 6 months. With no available on-label comparator, the primary endpoints of the present trial were determined using objective performance goals from a systematic literature search. The secondary endpoints included Tacked segment patency and target limb salvage at 6 months. The 6-month results are reported. RESULTS: Of the 233 patients enrolled, 117 (50.2%) had Rutherford class 5 and 78 (33.5%) had Rutherford class 4. A total of 341 post-PTA dissections were treated. Each patient received at least one Tack implant, and 100% of the dissections resolved according to the angiographic core laboratory findings. The primary safety and efficacy endpoints were both met. The rate of MALE plus POD at 30 days was 1.3% (3 of 228) and freedom from MALE at 6 months plus POD at 30 days was 95.6% (196 of 205). The 6-month Tacked segment patency was 82.1% (247 of 301) and target limb salvage was 98.5% (202 of 205). The Kaplan-Meier freedom from clinically driven target lesion revascularization and amputation-free survival at 6 months was 92.0% and 95.7%, respectively. Rutherford improvement was reported in 79.4% (158 of 199). Most (90 of 122; 73.8%) preexisting wounds had healed or were improving. CONCLUSIONS: The Tack Endovascular System is safe and effective for treating post-PTA BTK dissections through 6 months, with favorable rates of MALE plus POD, patency, clinically driven target lesion revascularization, limb salvage, and wound healing.

A critical appraisal of registry-based objective performance goals in peripheral arterial disease.

The multidisciplinary Superficial Femoral Artery-Popliteal EvidencE Development (SPEED) Study Group, under the auspices of the Registry Assessment of Peripheral Interventional Devices (RAPID) partnership, recently published objective performance goals for peripheral vascular interventions in the femoropopliteal arteries. Retrospective outcomes from the Vascular Quality Initiative provided the sole study data source. Strengths and weaknesses of this landmark effort are examined. Critical concerns include the substantial risks of ascertainment bias, flawed end point selection, sparse and variable capture of midterm follow-up data, and lack of expected discrimination between treatment modalities. The current Vascular Quality Initiative registry data thus appear insufficiently robust for the generation of objective performance goals and practice benchmarks; suggestions for redesign are provided. The impact of the statutory framework of the US Food and Drug Administration on device approval pathways and the maturation of an evidence-based approach to peripheral vascular intervention is explored.

Resident mesenchymal vascular progenitors modulate adaptive angiogenesis and pulmonary remodeling via regulation of canonical Wnt signaling.

Adaptive angiogenesis is necessary for tissue repair, however, it may also be associated with the exacerbation of injury and development of chronic disease. In these studies, we demonstrate that lung mesenchymal vascular progenitor cells (MVPC) modulate adaptive angiogenesis via lineage trace, depletion of MVPC, and modulation of ß-catenin expression. Single cell sequencing confirmed MVPC as multipotential vascular progenitors, thus, genetic depletion resulted in alveolar simplification with reduced adaptive angiogenesis. Following vascular endothelial injury, Wnt activation in MVPC was sufficient to elicit an emphysema-like phenotype characterized by increased MLI, fibrosis, and MVPC driven adaptive angiogenesis. Lastly, activation of Wnt/ß-catenin signaling skewed the profile of human and murine MVPC toward an adaptive phenotype. These data suggest that lung MVPC drive angiogenesis in response to injury and regulate the microvascular niche as well as subsequent distal lung tissue architecture via Wnt signaling.

The Upper Airway Microbiota, Environmental Exposures, Inflammation, and Disease.

Along with playing vital roles in pathogen exclusion and immune system priming, the upper airways (UAs) and their microbiota are essential for myriad physiological functions such as conditioning and transferring inhaled air. Dysbiosis, a microbial imbalance, is linked with various diseases and significantly impedes the quality of one's life. Daily inhaled exposures and/or underlying conditions contribute to adverse changes to the UA microbiota. Such variations in the microbial community exacerbate UA and pulmonary disorders via modulating inflammatory and immune pathways. Hence, exploring the UA microbiota's role in maintaining homeostasis is imperative. The microbial composition and subsequent relationship with airborne exposures, inflammation, and disease are crucial for strategizing innovating UA diagnostics and therapeutics. The development of a healthy UA microbiota early in life contributes to normal respiratory development and function in the succeeding years. Although different UA cavities present a unique microbial profile, geriatrics have similar microbes across their UAs. This lost community segregation may contribute to inflammation and disease, as it stimulates disadvantageous microbial-microbial and microbial-host interactions. Varying inflammatory profiles are associated with specific microbial compositions, while the same is true for many disease conditions and environmental exposures. A shift in the microbial composition is also detected upon the administration of numerous therapeutics, highlighting other beneficial and adverse side effects. This review examines the role of the UA microbiota in achieving homeostasis, and the impact on the UAs of environmental airborne pollutants, inflammation, and disease.

Therapeutic Potential of Alpha-1 Antitrypsin in Type 1 and Type 2 Diabetes Mellitus.

Alpha-1 antitrypsin (AAT) has established anti-inflammatory and immunomodulatory effects in chronic obstructive pulmonary disease but there is increasing evidence of its role in other inflammatory and immune-mediated conditions, like diabetes mellitus (DM). AAT activity is altered in both developing and established type 1 diabetes mellitus (T1DM) as well in established type 2 DM (T2DM). Augmentation therapy with AAT appears to favorably impact T1DM development in mice models and to affect ß-cell function and inflammation in humans with T1DM. The role of AAT in T2DM is less clear, but AAT activity appears to be reduced in T2DM. This article reviews these associations and emerging therapeutic strategies using AAT to treat DM.

Targeting c-Src Reverses Accelerated GPX-1 mRNA Decay in Chronic Obstructive Pulmonary Disease Airway Epithelial Cells.

Enhanced expression of the cellular antioxidant glutathione peroxidase (GPX)-1 prevents cigarette smoke-induced lung inflammation and tissue destruction. Subjects with chronic obstructive pulmonary disease (COPD), however, have decreased airway GPX-1 levels, rendering them more susceptible to disease onset and progression. The mechanisms that downregulate GPX-1 in the airway epithelium in COPD remain unknown. To ascertain these factors, analyses were conducted using human airway epithelial cells isolated from healthy subjects and human subjects with COPD and lung tissue from control and cigarette smoke-exposed A/J mice. Tyrosine phosphorylation modifies GPX-1 expression and cigarette smoke activates the tyrosine kinase c-Src. Therefore, studies were conducted to evaluate the role of c-Src on GPX-1 levels in COPD. These studies identified accelerated GPX-1 mRNA decay in COPD airway epithelial cells. Targeting the tyrosine kinase c-Src with siRNA inhibited GPX-1 mRNA degradation and restored GPX-1 protein levels in human airway epithelial cells. In contrast, silencing the tyrosine kinase c-Abl, or the transcriptional activator Nrf2, had no effect on GPX-1 mRNA stability. The chemical inhibitors for c-Src (saracatinib and dasanitib) restored GPX-1 mRNA levels and GPX-1 activity in COPD airway cells in vitro. Similarly, saracatinib prevented the loss of lung Gpx-1 expression in response to chronic smoke exposure in vivo. Thus, this study establishes that the decreased GPX-1 expression that occurs in COPD lungs is at least partially due to accelerated mRNA decay. Furthermore, these findings show that targeting c-Src represents a potential therapeutic approach to augment GPX-1 responses and counter smoke-induced lung disease.

Airway Resistance Caused by Sphingomyelin Synthase 2 Insufficiency in Response to Cigarette Smoke.

Sphingomyelin synthase is responsible for the production of sphingomyelin (SGM), the second most abundant phospholipid in mammalian plasma, from ceramide, a major sphingolipid. Knowledge of the effects of cigarette smoke on SGM production is limited. In the present study, we examined the effect of chronic cigarette smoke on sphingomyelin synthase (SGMS) activity and evaluated how the deficiency of Sgms2, one of the two isoforms of mammalian SGMS, impacts pulmonary function. Sgms2-knockout and wild-type control mice were exposed to cigarette smoke for 6 months, and pulmonary function testing was performed. SGMS2-dependent signaling was investigated in these mice and in human monocyte-derived macrophages of nonsmokers and human bronchial epithelial (HBE) cells isolated from healthy nonsmokers and subjects with chronic obstructive pulmonary disease (COPD). Chronic cigarette smoke reduces SGMS activity and Sgms2 gene expression in mouse lungs. Sgms2-deficient mice exhibited enhanced airway and tissue resistance after chronic cigarette smoke exposure, but had similar degrees of emphysema, compared with smoke-exposed wild-type mice. Sgms2-/- mice had greater AKT phosphorylation, peribronchial collagen deposition, and protease activity in their lungs after smoke inhalation. Similarly, we identified reduced SGMS2 expression and enhanced phosphorylation of AKT and protease production in HBE cells isolated from subjects with COPD. Selective inhibition of AKT activity or overexpression of SGMS2 reduced the production of several matrix metalloproteinases in HBE cells and monocyte-derived macrophages. Our study demonstrates that smoke-regulated Sgms2 gene expression influences key COPD features in mice, including airway resistance, AKT signaling, and protease production.

Cigarette smoke induction of S100A9 contributes to chronic obstructive pulmonary disease.

S100 calcium-binding protein A9 (S100A9) is elevated in plasma and bronchoalveolar lavage fluid (BALF) of patients with chronic obstructive pulmonary disease (COPD), and aging enhances S100A9 expression in several tissues. Currently, the direct impact of S100A9-mediated signaling on lung function and within the aging lung is unknown. Here, we observed that elevated S100A9 levels in human BALF correlated with age. Elevated lung levels of S100A9 were higher in older mice compared with in young animals and coincided with pulmonary function changes. Both acute and chronic exposure to cigarette smoke enhanced S100A9 levels in age-matched mice. To examine the direct role of S100A9 on the development of COPD, S100a9-/- mice or mice administered paquinimod were exposed to chronic cigarette smoke. S100A9 depletion and inhibition attenuated the loss of lung function, pressure-volume loops, airway inflammation, lung compliance, and forced expiratory volume in 0.05 s/forced vital capacity, compared with age-matched wild-type or vehicle-administered animals. Loss of S100a9 signaling reduced cigarette smoke-induced airspace enlargement, alveolar remodeling, lung destruction, ERK and c-RAF phosphorylation, matrix metalloproteinase-3 (MMP-3), matrix metalloproteinase-9 (MMP-9), monocyte chemoattractant protein-1 (MCP-1), interleukin-6 (IL-6), and keratinocyte-derived chemokine (KC) release into the airways. Paquinimod administered to nonsmoked, aged animals reduced age-associated loss of lung function. Since fibroblasts play a major role in the production and maintenance of extracellular matrix in emphysema, primary lung fibroblasts were treated with the ERK inhibitor LY3214996 or the c-RAF inhibitor GW5074, resulting in less S100A9-induced MMP-3, MMP-9, MCP-1, IL-6, and IL-8. Silencing Toll-like receptor 4 (TLR4), receptor for advanced glycation endproducts (RAGE), or extracellular matrix metalloproteinase inducer (EMMPRIN) prevented S100A9-induced phosphorylation of ERK and c-RAF. Our data suggest that S100A9 signaling contributes to the progression of smoke-induced and age-related COPD.