Background Interleukin 6 concentration is associated with myocardial injury, heart failure, and mortality after myocardial infarction. In the Norwegian tocilizumab non-ST-segment-elevation myocardial infarction trial, the first randomized trial of interleukin 6 blockade in myocardial infarction, concentration of both C-reactive protein and troponin T were reduced in the active treatment arm. In this follow-up study, an aptamer-based proteomic approach was employed to discover additional plasma proteins modulated by tocilizumab treatment to gain novel insights into the effects of this therapeutic approach. Methods and Results Plasma from percutaneous coronary intervention-treated patients, 24 in the active intervention and 24 in the placebo-control arm, drawn 48 hours postrandomization were randomly selected for analysis with the SOMAscan assay. Employing slow off-rate aptamers, the relative abundance of 1074 circulating proteins was measured. Proteins identified as being significantly different between groups were subsequently measured by enzyme immunoassay in the whole trial cohort (117 patients) at all time points (days 1-3 [7 time points] and 3 and 6 months). Five proteins identified by the SOMAscan assay, and subsequently confirmed by enzyme immunoassay, were significantly altered by tocilizumab administration. The acute-phase proteins lipopolysaccharide-binding protein, hepcidin, and insulin-like growth factor-binding protein 4 were all reduced during the hospitalization phase, as was the monocyte chemoattractant C-C motif chemokine ligand 23. Proteinase 3, released primarily from neutrophils, was significantly elevated. Conclusions Employing the SOMAscan aptamer-based proteomics platform, 5 proteins were newly identified that are modulated by interleukin 6 antagonism and may mediate the therapeutic effects of tocilizumab in non-ST-segment-elevation myocardial infarction.

Inflammation during brain development participates in the pathogenesis of early brain injury and cognitive dysfunctions. Prenatal ethanol exposure affects the developing brain and causes neural impairment, cognitive and behavioral effects, collectively known as fetal alcohol spectrum disorders (FASD). Our previous studies demonstrate that ethanol activates the innate immune response and TLR4 receptor and causes neuroinflammation, brain damage, and cognitive defects in the developmental brain stage of adolescents. We hypothesize that by activating the TLR4 response, maternal alcohol consumption during pregnancy triggers the release of cytokines and chemokines in both the maternal sera and brains of fetuses/offspring, which impairs brain ontogeny and causes cognitive dysfunction.

The pathophysiological mechanisms for vascular lesions in diabetes mellitus (DM) are complex, among which endothelial dysfunction plays a vital role. Therapeutic target against endothelial injury may provide critical venues for treatment of diabetic vascular diseases. We recently identified that salusin-β contributed to high glucose-induced endothelial cell apoptosis. However, the roles of salusin-β in DM-induced endothelial dysfunction remain largely elusive. Male C57BL/6J mice were used to induce type 2 diabetes mellitus (T2DM) model. Human umbilical vein endothelial cells (HUVECs) were cultured in high glucose/high fat (HG/HF) medium. We demonstrated increased expression of salusin-β in diabetic aortic tissues and high-glucose/high-fat- (HG/HF-) incubated HUVECs. Disruption of salusin-β by shRNA abrogated the reactive oxygen species (ROS) production, inflammation, and nitrotyrosine content of HUVECs cultured in HG/HF medium. The HG/HF-mediated decrease in peroxisome proliferator-activated receptor γ (PPARγ) expression was restored by salusin-β shRNA, and PPARγ inhibitor T0070907 abolished the protective actions of salusin-β shRNA on endothelial injury in HG/HF-treated HUVECs. Salusin-β silencing obviously improved endothelium-dependent vasorelaxation, oxidative stress, inflammatory response, and nitrative stress in diabetic aorta. Taken together, our results highlighted the essential role of salusin-β in pathological endothelial dysfunction, and salusin-β may be a promising target in treatment of vascular complications of DM.

Background Stress-induced cell premature senescence participates in a variety of tissue and organ remodeling by secreting such proteins as proinflammatory cytokines, chemokines, and growth factors. However, the role of cardiomyocyte senescence in heart remodeling after acute myocardial infarction has not been thoroughly elucidated to date. Therefore, we sought to clarify the impact of premature myocardial senescence on postinfarction heart function. Methods and Results Senescence markers, including p16 INK4a, p21 CIP1/WAF1, and SA -β-gal staining, were analyzed in several heart disease models by immunostaining. Both postinfarction mouse hearts and ischemic human myocardium demonstrated increased senescence markers. Additionally, senescence-related secretory phenotype was activated after acute myocardial infarction, which upregulated senescence-related secretory phenotype factors, including CCN family member 1 ( CCN 1), interleukin-1α, tumor necrosis factor α, and monocyte chemoattractant protein-1. In vivo, a tail vein injection of AAV 9- Gata4-sh RNA significantly attenuated senescence-related secretory phenotype secretion and aggravated postinfarction heart dysfunction. Furthermore, among activated senescence-related secretory phenotype factors, CCN 1 administration reduced myofibroblast viability in vitro and rescued the deleterious effect of AAV 9- Gata4-sh RNA in vivo. Conclusions Myocardial premature senescence was observed in the ischemic hearts and improved postinfarction heart function, partly through the GATA-binding factor 4- CCN 1 pathway.

Astrocytes form functionally and morphologically distinct populations of cells with brain-region-specific properties. Human pluripotent stem cells (hPSCs) offer possibilities to generate astroglia for studies investigating mechanisms governing the emergence of astrocytic diversity. We established a method to generate human astrocytes from hPSCs with forebrain patterning and final specification with ciliary neurotrophic factor (CNTF). Transcriptome profiling and gene enrichment analysis monitored the sequential expression of genes determining astrocyte differentiation and confirmed activation of forebrain differentiation pathways at Day 30 (D30) and D60 of differentiation in vitro. More than 90% of astrocytes aged D95 in vitro co-expressed the astrocytic markers glial fibrillary acidic protein (GFAP) and S100β. Intracellular calcium responses to ATP indicated differentiation of the functional astrocyte population with constitutive monocyte chemoattractant protein-1 (MCP-1/CCL2) and tissue inhibitor of metalloproteinases-2 (TIMP-2) expression. The method was reproducible across several hPSC lines, and the data demonstrated the usefulness of forebrain astrocyte modeling in research investigating forebrain pathology.

Increasing concerns over the possible risks of nanotechnology necessitates breakthroughs in structure-activity relationship (SAR) analyses of engineered nanomaterials (ENMs) at nano-bio interfaces. However, current nano-SARs are often based on univariate assessments and fail to provide tiered views on ENM-induced bio-effects. Here we report a multi-hierarchical nano-SAR assessment for a representative ENM, Fe2O3, by metabolomics and proteomics analyses. The established nano-SAR profile allows the visualizing of the contributions of seven basic properties of Fe2O3 to its diverse bio-effects. For instance, although surface reactivity is responsible for Fe2O3-induced cell migration, the inflammatory effects of Fe2O3 are determined by aspect ratio (nanorods) or surface reactivity (nanoplates). These nano-SARs are examined in THP-1 cells and animal lungs, which allow us to decipher the detailed mechanisms including NLRP3 inflammasome pathway and monocyte chemoattractant protein-1-dependent signaling. This study provides more insights for nano-SARs, and may facilitate the tailored design of ENMs to render them desired bio-effects.

Epileptic seizures are crucial clinical manifestations of recurrent neuronal discharges in the brain. An imbalance between the excitatory and inhibitory neuronal discharges causes brain damage and cell loss. Herbal medicines offer alternative treatment options for epilepsy because of their low cost and few side effects. We established a rat epilepsy model by injecting kainic acid (KA, 12 mg/kg, i.p.) and subsequently investigated the effect of Uncaria rhynchophylla (UR) and its underlying mechanisms. Electroencephalogram and epileptic behaviors revealed that the KA injection induced epileptic seizures. Following KA injection, S100B levels increased in the hippocampus. This phenomenon was attenuated by the oral administration of UR and valproic acid (VA, 250 mg/kg). Both drugs significantly reversed receptor potentiation for advanced glycation end product proteins. Rats with KA-induced epilepsy exhibited no increase in the expression of metabotropic glutamate receptor 3, monocyte chemoattractant protein 1, and chemokine receptor type 2, which play a role in inflammation. Our results provide novel and detailed mechanisms, explaining the role of UR in KA-induced epileptic seizures in hippocampal CA1 neurons.

Chemokines play a central role in immune and inflammatory responses. It has been observed recently that certain viruses have evolved molecular piracy and mimicry mechanisms by encoding and synthesizing proteins that interfere with the normal host defense response. One such viral protein, vMIP-II, encoded by human herpesvirus 8, has been identified with in vitro antagonistic activities against CC and CXC chemokine receptors. We report here that vMIP-II has additional antagonistic activity against CX3CR1, the receptor for fractalkine. To investigate the potential therapeutic effect of this broad-spectrum chemokine antagonist, we studied the antiinflammatory activity of vMIP-II in a rat model of experimental glomerulonephritis induced by an antiglomerular basement membrane antibody. vMIP-II potently inhibited monocyte chemoattractant protein 1-, macrophage inflammatory protein 1beta-, RANTES (regulated on activation, normal T cell expressed and secreted)-, and fractalkine-induced chemotaxis of activated leukocytes isolated from nephritic glomeruli, significantly reduced leukocyte infiltration to the glomeruli, and markedly attenuated proteinuria. These results suggest that molecules encoded by some viruses may serve as useful templates for the development of antiinflammatory compounds.

Lipid metabolism disorder is one of the significant risk factors for a multitude of human diseases and has become a serious threat to human health. The present study aimed to evaluate the effects of phenolics from poplar-type propolis on regulating lipid metabolism by using cell models of steatosis induced by palmitic acid (PA). Our study shows that phenolic esters have higher lipid-lowering activities than phenolic acids, especially for three caffeic acid esters, including caffeic acid phenethyl ester (CAPE), caffeic acid cinnamyl ester (CACE), and caffeic acid benzyl ester (CABE). Most notably, CACE presents prominent properties to prevent intracellular lipid accumulation and to amend extracellular adipokine secretion abnormalities. In addition, our results firstly reveal that CACE can alleviate lipid metabolism disorder through mediating protein kinase RNA-like endoplasmic reticulum kinase (PERK), activating transcription factor 6 (ATF6) signaling pathway-associated protein expression, suppressing endoplasmic reticulum (ER) stress, and activating peroxisome proliferator-activated receptors (PPARs) by distinct upregulation of PPARα and downregulation of PPARγ.

The disruption of mitochondrial redox homeostasis in endothelial cells (ECs) can cause chronic inflammation, a substantial contributor to the development of atherosclerosis. Chronic sympathetic hyperactivity can enhance oxidative stress to induce endothelial dysfunction. We determined if renal denervation (RDN), the strategy reducing sympathetic tone, can protect ECs by ameliorating mitochondrial reactive oxygen species (ROS)-induced inflammation to reduce atherosclerosis.

Parkinson's disease (PD) is characterised by the progressive loss of midbrain dopaminergic neurons and the presence of aggregated α-synuclein (α-syn). Pericytes and microglia, two non-neuronal cells contain α-syn in the human brain, however, their role in disease processes is poorly understood. Pericytes, found surrounding the capillaries in the brain are important for maintaining the blood-brain barrier, controlling blood flow and mediating inflammation. In this study, primary human brain pericytes and microglia were exposed to two different α-synuclein aggregates. Inflammatory responses were assessed using immunocytochemistry, cytometric bead arrays and proteome profiler cytokine array kits. Fixed flow cytometry was used to investigate the uptake and subsequent degradation of α-syn in pericytes. We found that the two α-syn aggregates are devoid of inflammatory and cytotoxic actions on human brain derived pericytes and microglia. Although α-syn did not induce an inflammatory response, pericytes efficiently take up and degrade α-syn through the lysosomal pathway but not the ubiquitin-proteasome system. Furthermore, when pericytes were exposed the ubiquitin proteasome inhibitor-MG132 and α-syn aggregates, there was profound cytotoxicity through the production of reactive oxygen species resulting in apoptosis. These results suggest that the observed accumulation of α-syn in pericytes in human PD brains likely plays a role in PD pathogenesis, perhaps by causing cerebrovascular instability, under conditions of cellular stress.

Kidney ischemia/reperfusion (I/R) injury, a common cause of acute kidney injury (AKI), is associated with the migration of inflammatory cells into the kidney. Ras-related C3 botulinum toxin substrate 1 (Rac1), a member of the Rho family of small GTPase, plays an important role in inflammatory cell migration by cytoskeleton rearrangement. Here, we investigated the role of Rac1 on kidney I/R injury and macrophage migration. Male mice were subjected to either 25 min of bilateral ischemia followed by reperfusion (I/R) or a sham operation. Some mice were administrated with either NSC23766, an inhibitor of Rac1, or 0.9% NaCl (vehicle). Kidney damage and Rac1 activity and expression were measured. The migration and lamellipodia formation of RAW264.7 cells, mouse monocyte/macrophage, induced by monocyte chemoattractant protein-1 (MCP-1, a chemokine) were determined using transwell migration assay and phalloidin staining, respectively. In sham-operated kidneys, Rac1 was expressed in tubular cells and interstitial cells. In I/R-injured kidneys, Rac1 expression was decreased in tubule cells in correlation with the damage of tubular cells, whereas Rac1 expression increased in the interstitium in correlation with an increased population of F4/80 cells, monocytes/macrophages. I/R increased Rac1 activity without changing total Rac1 expression in the whole kidney lysates. NSC23766 administration blocked Rac1 activation and protected the kidney against I/R-induced kidney damage and interstitial F4/80 cell increase. NSC23766 suppressed monocyte MCP-1-induced lamellipodia and filopodia formation and migration of RAW 264.7 cells. These results indicate Rac1 inhibition protects the kidney against I/R via inhibition of monocytes/macrophages migration into the kidney.

The suppressive effects of flavonoids on macrophage-associated adipocyte inflammation in a differentiated murine preadipocyte cell line (3T3-L1) co-cultured with a murine macrophage cell line (RAW264.7) were evaluated. Extracellular lipid accumulation was investigated via Oil Red O staining. The expression levels of adipogenesis- and inflammation-associated proteins, including CCAAT/enhancer-binding protein (C/EBP)-α, inducible nitric oxide synthase (iNOS), C/EBPβ, peroxisome proliferator-activated receptor γ (PPARγ), and cyclooxygenase-2 (COX-2), were determined via Western blotting. Proinflammatory cytokines, including monocyte chemoattractant protein 1 (MCP-1) and interleukin-6 (IL-6), were assessed using enzyme-linked immunosorbent assay kits. We found that silybin, formononetin, and diosmetin inhibited lipid accumulation and production of proinflammatory cytokines in the co-cultures of 3T3-L1 and RAW264.7 cells. Moreover, they inhibited the protein expression of PPARγ, C/EBPα, COX-2, C/EBPβ, and iNOS in the co-cultures of 3T3-L1 and RAW264.7 cells. These data support that silybin, formononetin, and diosmetin inhibit macrophage-associated adipocyte inflammation and lipid accumulation.

Heat shock factor 1 (HSF1) is a transcription factor involved in the heat shock response and other biological processes. We have unveiled here an important role of HSF1 in acute lung injury (ALI). HSF1 knockout mice were used as a model of lipopolysaccharide- (LPS-) induced ALI. Lung damage was aggravated, and macrophage infiltration increased significantly in the bronchoalveolar lavage fluid (BALF) and lung tissue of HSF-/- mice compared with the damage observed in HSF1+/+ mice. Upon LPS stimulation, HSF-/- mice showed higher levels of monocyte chemoattractant protein-1 (MCP-1) in the serum, BALF, and lung tissue and increased the expression of MCP-1 and chemokine (C-C motif) receptor 2 (CCR2) on the surface of macrophages compared with those in HSF1+/+. Electrophoretic mobility shift assays (EMSA) and dual luciferase reporter assays revealed that HSF1 could directly bind to heat shock elements (HSE) in the promoter regions of MCP-1 and its receptor CCR2, thereby inhibiting the expression of both genes. We concluded that HSF1 attenuated LPS-induced ALI in mice by directly suppressing the transcription of MCP-1/CCR2, which in turn reduced macrophage infiltration.

Myrciaria cauliflora is a functional food rich in anthocyanins, possessing antioxidative and anti-inflammatory properties. Our previous results demonstrated M. cauliflora extract (MCE) had beneficial effects in diabetic nephropathy (DN) and via the inhibition of Ras/PI3K/Akt and kidney fibrosis-related proteins. The purpose of this study was to assess the benefit of MCE in diabetes associated with kidney inflammation and glycemic regulation in streptozotocin-nicotinamide (STZ/NA)-induced diabetic mice. Compared with the untreated diabetic group, MCE significantly improved blood glucose and serum biochemical characteristic levels. Exposure to MCE increased antioxidative enzyme activity and diminished reactive oxygen synthesis. Mice receiving MCE supplementation had reduced intercellular adhesion molecule-1 (ICAM-1), vascular cell adhesion molecule-1 (VCAM-1), monocyte chemoattractant protein 1 (MCP-1), colony stimulating factor 1 (CSF-1), interleukin-1β (IL-1β), IL-6 and tumor necrosis factor α (TNF-α) levels compared to the untreated diabetic mice. Inflammatory and fibrotic related proteins such as collagen IV, fibronectin, Janus kinase (JAK), phosphorylated signal transducer and activator of transcription 3 (STAT3), protein kinase C beta (PKC-β), and nuclear factor kappa B (NF-κB) were also inhibited by MCE treatment in STZ/NA mice. These results suggest that MCE may be used as a hypoglycemic agent and antioxidant in Type 2 diabetic mice.

The low-pressure spark plasma sintering (SPS) technique is adopted to fabricate hydroxyapatite-bioglass (HA-BG) scaffolds while maintaining the physical properties of both components, including their bulk and relative density and hardness. However, prior to their orthopaedic and dental applications, these scaffolds must be validated via pre-clinical assessments. In the present study, scaffolds with different ratios of HA : BG, namely, 100 : 0 (HB 0 S), 90 : 10 (HB 10 S), 80 : 20 (HB 20 S) and 70 : 30 (HB 30 S) were fabricated. These scaffolds were characterized by investigating their physicochemical properties (X-ray diffraction (XRD) and surface wettability), bioactivity in a simulated body fluid (SBF) (field emission scanning electron microscopy (FESEM), Fourier-transform infrared spectroscopy (FTIR) and calcium dissolution), antimicrobial properties, biocompatibility and osteoinduction of human bone marrow-derived mesenchymal stromal cells (hBMSCs) and human monocyte immune cell response. The XRD and surface wettability results confirmed no formation of undesirable phases and the enhanced surface hydrophilicity of the scaffolds, respectively. The bioactivity in SBF indicated the formation of bone-like apatite on the surface of the scaffolds, corresponding to an increase in BG%, which was confirmed through FTIR spectra and the increasing trend of calcium release in SBF. The scaffolds showed inhibition properties against Staphylococcus aureus and Staphylococcus epidermidis. The scanning electron microscopy (SEM) micrographs and Alamar Blue proliferation assay indicated the good attachment and significant proliferation, respectively, of hBMSCs on the scaffolds. Alizarin Red S staining confirmed that the scaffolds supported the mineralisation of hBMSCs. The osteogenic protein secretion (bone morphogenetic protein-2 (BMP2), type-I collagen (COL1) and osterix (OSX)) was significant on the HB 30 S-seeded hBMSCs when compared with that of HB 0 S. The monocyte migration was significantly halted in response to HA-BG-conditioned media when compared with the positive control (monocyte chemoattractant protein-1: MCP-1). In conclusion, the HB 30 S composite scaffold has a greater potential to substitute bone grafts in orthopaedic and dental applications.

Enamel matrix derivative (EMD) has been found to induce reactive dentin formation; however the molecular mechanisms involved are unclear. The effect of EMD (5-50 μg/mL) on primary human pulp cells were compared to untreated cells and cells incubated with 10⁻⁸ M dexamethasone (DEX) for 1, 2, 3, 7, and 14 days in culture. Expression analysis using Affymetrix microchips demonstrated that 10 μg/mL EMD regulated several hundred genes and stimulated the gene expression of proteins involved in mesenchymal proliferation and differentiation. Both EMD and DEX enhanced the expression of amelogenin (amel), and the dentinogenic markers dentin sialophosphoprotein (DSSP) and dentin matrix acidic phosphoprotein 1 (DMP1), as well as the osteogenic markers osteocalcin (OC, BGLAP) and collagen type 1 (COL1A1). Whereas, only EMD had effect on alkaline phosphatase (ALP) mRNA expression, the stimulatory effect were verified by enhanced secretion of OC and COL1A from EMD treated cells, and increased ALP activity in cell culture medium after EMD treatment. Increased levels of interleukin-6 (IL-6), interleukin-8 (IL-8), and monocyte chemoattractant proteins (MCP-1) in the cell culture medium were also found. Consequently, the suggested effect of EMD is to promote differentiation of pulp cells and increases the potential for pulpal mineralization to favor reactive dentine formation.

Obesity is a constantly increasing health problem worldwide. It is associated with a systemic low-grade inflammation, which contributes to the development of metabolic disorders and comorbidities such as type 2 diabetes. Diet has an important role in the prevention of obesity and its adverse health effects; as a part of healthy diet, polyphenol-rich berries, such as lingonberry (Vaccinium vitis-idaea L.) have been proposed to have health-promoting effects. In the present study, we investigated the effects of lingonberry supplementation on high-fat diet induced metabolic and inflammatory changes in a mouse model of obesity. Thirty male C57BL/6N mice were divided into three groups (n = 10/group) to receive low-fat (LF), high-fat (HF) and lingonberry-supplemented high-fat (HF+LGB) diet for six weeks. Low-fat and high-fat diet contained 10% and 46% of energy from fat, respectively. Lingonberry supplementation prevented the high-fat diet induced adverse changes in blood cholesterol and glucose levels and had a moderate effect on the weight and visceral fat gain, which were 26% and 25% lower, respectively, in the lingonberry group than in the high-fat diet control group. Interestingly, lingonberry supplementation also restrained the high-fat diet induced increases in the circulating levels of the proinflammatory adipocytokine leptin (by 36%) and the inflammatory acute phase reactant serum amyloid A (SAA; by 85%). Similar beneficial effects were discovered in the hepatic expression of the inflammatory factors CXCL-14, S100A10 and SAA by lingonberry supplementation. In conclusion, the present results indicate that lingonberry supplementation significantly prevents high-fat diet induced metabolic and inflammatory changes in a murine model of obesity. The results encourage evaluation of lingonberries as a part of healthy diet against obesity and its comorbidities.

Oxidative stress is one of the primary factors leading to endothelial dysfunction, a major underlying cause of vascular disorders. This study aims to understand the key signalling pathways regulated by sorghum (Shawaya short black 1 variety; characterised to be very high in its antioxidant activity) under oxidative stress in endothelial cells. Human umbilical vein endothelial cells (HUVECs) were pre-treated with non-cytotoxic concentrations of phenolic-rich black sorghum extract (BSE) prior to induction of oxidative stress using hydrogen peroxide (H2O2). Treatment with BSE upregulated the expression of heme oxygenase 1 (HO1) and endothelial nitric oxide synthase (eNOS) and downregulated the levels of NADPH oxidase 4 (NOX4). BSE treatment significantly reduced the expression of pro-inflammatory mediators such as monocyte chemoattractant protein 1 (MCP1) and intracellular adhesion molecule 1 (ICAM1). Results from this study suggest that phenolic-rich BSE may reduce oxidative stress by regulating pro- and antioxidant signalling pathways and the expression of inflammatory mediators linked to endothelial dysfunction under oxidative stress.

Cigarette smoke exposure (CS) is the main risk factor for chronic obstructive pulmonary disease (COPD). Macrophages have an important role in COPD because they release pro-inflammatory and anti-inflammatory cytokines. The present study's we investigate the functional changes in macrophages and monocytes exposed to cigarette smoke extract (CSE). Herein, using human monocyte-derived macrophages (MDMs) from healthy donors and we found that CSE was not associated with significant changes in the production of pro inflammatory cytokines by MDMs. In contrast, exposure to CSE suppressed the production of IL-6 and Gro-a/CXCL1 by LPS-stimulated-MDMs, but had an additive effect on the release of IL-8/CXCL8 and MCP1/CCL2. However, CSE exposure was associated with greater production, TARC/CCL-17 and CCL22/MDC. Moreover, MDMs displayed a lower uptake capacity after CSE exposure. We identify, for what is to our knowledge the first time that monocytes from patients with COPD produced less IL-8/CXCL8 and Gro-α/CXCL1 after LPS stimulation and produced higher levels of TARC/CCL17 and MDC/CCL-22 after IL-4 stimulation. Our present results highlighted a skewed immune response, with an imbalance in M1 vs. M2 cytokine production. In conclusion, exposure to CS has contrasting, multifaceted effects on macrophages and monocytes. Our data may provide a better understanding of the mechanisms underlying COPD.