The role of bronchial epithelial cells in the pathogenesis of COPD in Z-alpha-1 antitrypsin deficiency

Analysis of alpha-1-antitrypsin (AAT)-regulated, glucocorticoid receptor-dependent genes in macrophages reveals a novel host defense function of AAT

Alpha-1-antitrypsin (AAT) plays a homeostatic role in attenuating excessive inflammation and augmenting host defense against microbes. We demonstrated previously that AAT binds to the glucocorticoid receptor (GR) resulting in significant anti-inflammatory and antimycobacterial consequences in macrophages. Our current investigation aims to uncover AAT-regulated genes that rely on GR in macrophages. We incubated control THP-1 cells (THP-1control) and THP-1 cells knocked down for GR (THP-1GR-KD) with AAT, performed bulk RNA sequencing, and analyzed the findings. In THP-1control cells, AAT significantly upregulated 408 genes and downregulated 376 genes. Comparing THP-1control and THP-1GR-KD cells, 125 (30.6%) of the AAT-upregulated genes and 154 (41.0%) of the AAT-downregulated genes were significantly dependent on GR. Among the AAT-upregulated, GR-dependent genes, CSF-2 that encodes for granulocyte-monocyte colony-stimulating factor (GM-CSF), known to be host-protective against nontuberculous mycobacteria, was strongly upregulated by AAT and dependent on GR. We further quantified the mRNA and protein of several AAT-upregulated, GR-dependent genes in macrophages and the mRNA of several AAT-downregulated, GR-dependent genes. We also discussed the function(s) of selected AAT-regulated, GR-dependent gene products largely in the context of mycobacterial infections. In conclusion, AAT regulated several genes that are dependent on GR and play roles in host immunity against mycobacteria.

Analysis of the expression of the Serpina1 gene in SARS-CoV-2 infection: study of a new biomarker

INTRODUCTION

The SERPINA1 gene encodes the protein Alpha-1 Antitrypsin (AAT1). Possible imbalances between the concentrations of proteases and antiproteases (AAT1) can lead to the development of serious pulmonary and extrapulmonary pathologies. In this work we study the importance of this possible imbalance in patients with COVID-19.

OBJECTIVES

To correlate the severity of the symptoms of SARS-COV-2 infection with the AAT1 concentrations at diagnosis of the disease.

METHODS

An observational, prospective, cross-sectional, non-interventional, analytical study was carried out where 181 cases with COVID-19 admitted to the "Lozano Blesa" University Clinical Hospital of Zaragoza were selected. The concentration of AAT1 was studied in all of them and this was correlated with the clinical aspects and biochemical parameters at hospital admission.

RESULTS

141 cases corresponded to patients with severe COVID and 40 patients with mild COVID. AAT1 levels were positively correlated with the days of hospitalization, severity, C-Reactive Protein, ferritin, admission to Intensive Care, and death, and presented a negative correlation with the number of lymphocytes/mm3. AAT1 concentrations higher than 237.5 mg/dL allowed the patient to be classified as "severe" (S72%; E78%) and 311.5 mg/dL were associated with the risk of admission to Intensive Care or Exitus (S67%; E79%).

CONCLUSIONS

Levels of the SERPINA1 gene expression product, AAT1, correlate with the severity of COVID-19 patients at diagnosis of the disease, being useful as a prognostic biomarker.

Salivary Biomarkers to Differentiate between Streptococcus pneumoniae and Influenza A Virus-Related Pneumonia in Children

Community-acquired pneumonia (CAP) is common among children and can be fatal in certain conditions. In children, CAP can be caused by viral or bacterial infections. Identification of pathogens can help select appropriate therapeutic strategies. Salivary analysis may be a potential diagnostic tool because it is noninvasive, patient-friendly, and easy to perform in children. A prospective study was conducted in children with pneumonia admitted to a hospital. Salivary samples from patients with definite Streptococcus pneumoniae and influenza A strains were used for gel-free (isobaric tag for relative and absolute quantitation (iTRAQ)) proteomics. No statistically significant difference was detected in salivary CRP levels between Streptococcus pneumoniae and influenza A pneumonia in children. Several potential salivary biomarkers were identified using gel-free iTRAQ proteomics to differentiate pneumonia from Streptococcus pneumoniae or influenza A virus infections in pediatric patients. ELISA validated that Streptococcus pneumoniae group has a higher abundance of salivary alpha 1-antichymotrypsin than those in the influenza A group. Whether these salivary biomarkers can be used to distinguish other bacteria from viral pneumonia requires further verification.

Six-Minute Walking Test and 30 Seconds Chair-Stand-Test as Predictors of Mortality in COPD - A Cohort Study

Background

Physical inactivity is strongly associated with worse prognosis in Chronic Obstructive Pulmonary Disease (COPD), and assessment of physical function is very important. The six minute walking test (6MWT) is an established test known to predict mortality in COPD, and 30 seconds chair stand test (30sCST) is a potential alternative test. The study aimed to investigate and compare the associations of 6MWT and 30sCSTs with mortality.

Methods

Data on patient demographics, established mortality predictors and results from 6MWT and 30sCST were collected from 2016 to 2019 from 97 consecutively included patients with COPD. In August 2021, mortality data were retrieved from patient records. Correlation analysis of 6MWT and 30sCST was performed. The predictive abilities of 6MWT and 30sCST, respectively, were analyzed using Kaplan Meyer-curves and Cox regression with adjustment for sex, age, body mass index below 22 and comorbid cardiovascular disease.

Results

A positive correlation between 6MWT and 30sCST was shown (r = 0.61, p < 0.0001). Independent associations with mortality were found for 6MWD 250–349 (HR (95% CI) 3.19 (1.12 to 9.10), p = 0.030) and 6MWD <250 (4.27 (1.69 to10.8), p = 0.002) compared with 6MWD ≥350 meters, and for 30sCST <4 (3.31 (1.03 to 10.6), p = 0.045) compared with 30sCST≥11 risings. When both 6MWT and 30sCST were included in the multivariable model, 6MWD 250–349 (3.09 (1.02 to 9.37), p = 0.046) and 6MWD <250 (3.57 (1.26 to 10.1), p = 0.016) compared with 6MWD ≥350 meters predicted mortality.

Conclusion

30sCST and 6MWT correlates moderately and are independently associated with mortality in patients with COPD. Although 6MWT is the best predictor of mortality, 30sCST may be used as an alternative to identify patients at risk.

Alpha1-antitrypsin deficiency and cardiovascular disease: questions and issues of a debated relation

Alpha1-antitrypsin (AAT) is one of the major inhibitors involved in protease/antiprotease homeostasis, and it is mainly produced by hepatocytes and pulmonary epithelial cells. Its deficiency, called alpha1-antitrypsin deficit (AATD), leads to severe hepatic and respiratory issues. Also, AAT is released into the bloodstream providing systemic anti-inflammatory effects. Apart from acting as an acute-phase anti-inflammatory protein, it can be a biomarker for monitoring disease evolution. A reduced or defective production leads to a loss of anti-inflammatory function, protease-antiprotease imbalance and cellular engorgement due to polymers deposition, with system-wide repercussions. This review aims to evaluate AATD condition in the major vessels of the head and neck, thoracic and abdominal districts. Also, a dedicated focus on autoimmune vascular diseases will be provided. A critical revision of the main literature findings starting from the 1980s until now has been performed. Studies conducted over the years have provided several contradictory pieces of evidence. Most authors acknowledge the protective and anti-inflammatory AAT role on the vascular endothelium. However, correlations between AATD and major arteries, cerebral and cardiovascular conditions, and autoimmune diseases remain unclear. Most studies recognize the role of AATD in vascular diseases but only as a cofactor inducing cellular and tissue structure impairments. However, this condition alone is not enough to determine new disease onset. Due to the opposing results reported over the years, there is still a considerable lack of knowledge on the role covered by AATD in vascular diseases. A renewed interest in this research field should be encouraged to grant new solid evidence and validate the putative role of AATD screening and replacement therapy as useful diagnostic and treatment tools.

Cigarette smoke exposed airway epithelial cell-derived EVs promote pro-inflammatory macrophage activation in alpha-1 antitrypsin deficiency

BACKGROUND

Alpha-1 antitrypsin deficiency (AATD) is a genetic disorder most commonly secondary to a single mutation in the SERPINA1 gene (PI*Z) that causes misfolding and accumulation of alpha-1 antitrypsin (AAT) in hepatocytes and mononuclear phagocytes which reduces plasma AAT and creates a toxic gain of function. This toxic gain of function promotes a pro-inflammatory phenotype in macrophages that contributes to lung inflammation and early-onset COPD, especially in individuals who smoke cigarettes. The aim of this study is to determine the role of cigarette exposed AATD macrophages and bronchial epithelial cells in AATD-mediated lung inflammation.

METHODS

Peripheral blood mononuclear cells from AATD and healthy individuals were differentiated into alveolar-like macrophages and exposed to air or cigarette smoke while in culture. Macrophage endoplasmic reticulum stress was quantified and secreted cytokines were measured using qPCR and cytokine ELISAs. To determine whether there is "cross talk" between epithelial cells and macrophages, macrophages were exposed to extracellular vesicles released by airway epithelial cells exposed to cigarette smoke and their inflammatory response was determined.

RESULTS

AATD macrophages spontaneously produce several-fold more pro-inflammatory cytokines as compared to normal macrophages. AATD macrophages have an enhanced inflammatory response when exposed to cigarette smoke-induced extracellular vesicles (EVs) released from airway epithelial cells. Cigarette smoke-induced EVs induce expression of GM-CSF and IL-8 in AATD macrophages but have no effect on normal macrophages. Release of AAT polymers, potent neutrophil chemo attractants, were also increased from AATD macrophages after exposure to cigarette smoke-induced EVs.

CONCLUSIONS

The expression of mutated AAT confers an inflammatory phenotype in AATD macrophages which disposes them to an exaggerated inflammatory response to cigarette smoke-induced EVs, and thus could contribute to progressive lung inflammation and damage in AATD individuals.

Acute Effect of Bronchodilator on Intrathoracic Airway Wall Compliance in COPD Patients

Purpose

In patients with chronic obstructive pulmonary disease (COPD), bronchial responsiveness after acute administration of short acting bronchodilators is conventionally assessed by measuring the improvement of forced expiratory volume in the first second (FEV₁) during a maximal forced expiratory maneuver. This study aimed to measure the variation of intrathoracic airway wall compliance (AWC) after acute administration of short acting beta-2 agonist in COPD patients since this might influence the final modification of airway caliber during maximal expiratory effort and the resulting bronchodilation as inferred by FEV₁ changes.

Methods

In a group of 10 patients suffering from COPD, intrathoracic AWC was measured at middle (50% of Forced Vital Capacity (FVC) and low (75% of FVC) lung volumes using the interrupter method during forced expiratory maneuver in basal conditions and after acute inhalation of albuterol (salbutamol) (400 mcg by MDI). Ten healthy subjects were examined similarly as a control group.

Results

Lower values of baseline intrathoracic AWC at both lung volumes were found in COPD patients (1.72 ± 0.20 ml/cmH₂O and 1.08 ± 0.20 ml/cmH₂O, respectively) as compared to controls (2.28 ± 0.27 ml/cmH₂O and 1.44 ± 0.22 ml/cmH₂O, respectively) (p < 0.001). In COPD patients, AWC increased significantly at both lung volumes after salbutamol, amounting to 1.81 ± 0.38 ml/cmH₂O and 1.31 ± 0.39 ml/cmH₂O, respectively (p < 0.01), but the relative change was not different from that observed in controls.

Conclusion

In COPD patients, AWC is reduced compared to controls, but after bronchodilator, the intrathoracic airways become more compliant. The consequent increased collapsibility under high positive pleural pressure could limit the airway caliber improvement seen after bronchodilator, as assessed by the FEV₁ changes during the forced expiratory maneuver, underestimating the effective bronchodilation achieved in these patients.

LMAN1-MCFD2 complex is a cargo receptor for the ER-Golgi transport of α1-antitrypsin

α1-antitrypsin (AAT) is a serine protease inhibitor synthesized in hepatocytes and protects the lung from damage by neutrophil elastase. AAT gene mutations result in AAT deficiency (AATD), which leads to lung and liver diseases. The AAT Z variant forms polymer within the endoplasmic reticulum (ER) of hepatocytes and results in reduction of AAT secretion and severe disease. Previous studies demonstrated a secretion defect of AAT in LMAN1 deficient cells, and mild decreases in AAT levels in male LMAN1 and MCFD2 deficient mice. LMAN1 is a transmembrane lectin that forms a complex with a small soluble protein MCFD2. The LMAN1-MCFD2 protein complex cycles between the ER and the Golgi. Here we report that LMAN1 and MCFD2 knockout (KO) HepG2 and HEK293T cells display reduced AAT secretion and elevated intracellular AAT levels due to a delayed ER-to-Golgi transport of AAT. Secretion defects in KO cells were rescued by wild-type LMAN1 or MCFD2, but not by mutant proteins. Elimination of the second glycosylation site of AAT abolished LMAN1 dependent secretion. Co-immunoprecipitation experiment in MCFD2 KO cells suggested that AAT interaction with LMAN1 is independent of MCFD2. Furthermore, our results suggest that secretion of the Z variant, both monomers and polymers, is also LMAN1-dependent. Results provide direct evidence supporting that the LMAN1-MCFD2 complex is a cargo receptor for the ER-to-Golgi transport of AAT and that interactions of LMAN1 with an N-glycan of AAT is critical for this process. These results have implications in production of recombinant AAT and in developing treatments for AATD patients.

A Review of Alpha-1 Antitrypsin Binding Partners for Immune Regulation and Potential Therapeutic Application

Alpha-1 antitrypsin (AAT) is the canonical serine protease inhibitor of neutrophil-derived proteases and can modulate innate immune mechanisms through its anti-inflammatory activities mediated by a broad spectrum of protein, cytokine, and cell surface interactions. AAT contains a reactive methionine residue that is critical for its protease-specific binding capacity, whereby AAT entraps the protease on cleavage of its reactive centre loop, neutralises its activity by key changes in its tertiary structure, and permits removal of the AAT-protease complex from the circulation. Recently, however, the immunomodulatory role of AAT has come increasingly to the fore with several prominent studies focused on lipid or protein-protein interactions that are predominantly mediated through electrostatic, glycan, or hydrophobic potential binding sites. The aim of this review was to investigate the spectrum of AAT molecular interactions, with newer studies supporting a potential therapeutic paradigm for AAT augmentation therapy in disorders in which a chronic immune response is strongly linked.

Investigating the Link between Alpha-1 Antitrypsin Deficiency and Abdominal Aortic Aneurysms

BACKGROUND

Alpha-1-Antitrypsin (AAT) is one of the major plasmatic protease inhibitors. In the last decade, an association between Alpha-1-Antitrypsin Deficiency (AATD) and Abdominal Aortic Aneurysms (AAA) has been hypothesized. Multiple factors may be involved in AAA's etiopathogenesis, and an underlying structural defect of the extracellular matrix (ECM) is always present. AATD could be a reasonable risk factor for AAA because it is related to protease/antiprotease imbalance and enhanced ECM degradation of the vessel wall.

METHODS

We performed genotyping of 138 patients hospitalized in the Vascular Surgery Division of the ASST-Spedali Civili di Brescia, Italy, for nontraumatic rupture of AAA. The second purpose was to observe the distribution of main nongenetic risk factors for AAA between patients with and without AATD.

RESULTS

Out of 138 patients, 22 were found with AATD: 16 MS, 1 SS, 3 MZ, and 2 with a new rare AAT variant. When compared to the general Italian population, our cohort's frequency of deficient S allele was significantly higher (7.8 vs. 2.2% respectively, P < 0.01), whereas the deficient Z allele was similar (1.1 vs. 1.3% respectively, P > 0.05). Although we found no differences in age, gender, hypertension, diabetes, and smoke habits between AAA patients with and without AATD, hyperlipidemia was significantly less frequent in patients with AATD (46.4 vs. 12.5% respectively, P < 0.05).

CONCLUSIONS

In our AAA patients' cohort, the S allele frequency was higher than in the general Italian population. Our results support the hypothesis that AATD might be a risk factor for AAA.

Z-alpha1-antitrypsin polymers and small airways disease: a new paradigm in alfa-1 anti-trypsin deficiency-related COPD development?

The presence of Alpha1-Antitrypsin (AAT) polymers, known to promote a sustained pro-inflammatory activity, has been previously demonstrated in bronchial biopsies of subjects with Z-AAT deficiency (AATD) suggesting a possible role in the development of COPD through a small airway disease impairment. The study aimed to assess the presence of small airways dysfunction and the potential correlation with the presence of Z-AAT polymers obtained by Exhaled Breath Condensate (EBC) collection in PiZZ subjects, as compared with matched healthy PiMM subjects. We enrolled 19 asymptomatic, never smoker subjects: 9 PiZZ and 10 PiMM as controls, without obstructive ventilatory defect (i.e., normal FEV1/VC% ratio). All subjects underwent complete pulmonary function tests (PFT). EBC was collected in all subjects. ELISA test was applied to search for Z-AAT polymers. The PiZZ subjects showed normal lung volumes and DLCO values. However, in comparison with PiMM subjects, the single breath test N2 wash-out revealed significant differences regarding the phase III slope (1.45±0.35 N2/L vs. 0.96±0.40 N2/L) (p<0.02) in the PiZZ subjects, while the closing volume/vital capacity ratio (14.3±4.5 % vs. 11.3±6.3 %) was not significantly increased. The ELISA test detected the presence of Z-AAT polymers in 44% of PiZZ patients. Asymptomatic, never smoker PiZZ subjects with normal spirometry and lung diffusion capacity showed airways impairment when compared to PiMM subjects. Although Z-AAT polymers were found only in 44% of PiZZ subjects, these findings suggest the possibility that chronic bronchiolitis can develop as a result of the long-term pro-inflammatory activity of Z-AAT polymers in subjects with Z-related AATD.

Alpha1-antitrypsin deficiency and asthma

PURPOSE OF REVIEW

The aim of the article is to highlight the association between α1-antitrypsin deficiency (AATD) and asthma.

RECENT FINDINGS

AATD is one of the most common and underrecognized autosomal disorders associated with an increased risk of developing liver and lung diseases. An association between α1-antitrypsin and asthma has been suggested, especially with severe forms of this disease. Many studies have shown an increased prevalence of asthma in the α1-antitrypsin-deficient population overtime (4-38%). The biological mechanism underlying these two conditions and able to bind them has not yet been well investigated. As α1-antitrypsin is the main inhibitor of the serine proteinase and it is an important anti-inflammatory protein with pronounced immunomodulatory activities, it can be hypothesized that the link between AATD and asthma might be represented by the elastase/antielastase imbalance and the proinflammatory effect that occurs because of the reduction of this protein.

SUMMARY

There is a strong need for further researches to better understand the molecular mechanisms binding AATD and asthma. It is also recommendable to screen for AATD, late-onset asthma patients, and/or those with not fully reversible airways obstruction.

Update on α1-antitrypsin deficiency

α₁-Antitrypsin deficiency (AATD) is an inherited metabolic disorder in which mutations in the coding sequence of the SERPINA1 gene prevent secretion of α₁-antitrypsin (α₁-AT) and cause predisposition to pulmonary and liver diseases. The heterogeneity of clinical manifestations in AATD is related to the complexity of biological function of α₁-AT. The role of smoking is crucial in the natural history of lung damage progression in severe AATD individuals, even if it also partly explains the heterogeneity in lung disease. Lung damage progression in AATD can also be related to body mass index, exacerbation rate, sex, environmental exposure and specific mutations of SERPINA1. Recent randomised controlled trials, together with previous observational work, have provided compelling evidence for the importance of early detection and intervention in order to enable patients to receive appropriate treatment and preserve functional lung tissue.

Early detection and intervention in cases of α₁-antitrypsin deficiency are essential to enable appropriate treatment and preserve functional lung tissuehttp://ow.ly/Mr3P30jUEyn

The important role of primary care providers in the detection of alpha-1 antitrypsin deficiency

OBJECTIVE

Alpha-1 antitrypsin deficiency (AATD) is an underrecognized genetic disorder that can cause chronic obstructive pulmonary disease (COPD) and liver cirrhosis, two clinical conditions commonly seen by primary care physicians. AATD is estimated to affect 1/4000-1/5000 people in the United States and 1-2% of all COPD cases.

METHODS

PubMed was searched for relevant articles using AAT/AATD-related terms.

RESULTS

Unfortunately, <10% of symptomatic individuals have been properly diagnosed primarily due to the underdiagnosis of COPD and the lack of awareness of AATD as a possible underlying cause. Because primary care providers are most likely to be the first to encounter symptomatic individuals, their role in the identification and early diagnosis of AATD patients is instrumental, particularly since therapy to slow lung disease progression is available. The diagnosis of AATD is laboratory-based rather than clinical. Testing for AATD should be part of the reflex testing that follows any COPD diagnosis or unexplained liver disease and can be performed by determining the AAT phenotype or genotype along with serum AAT levels. Both nonpharmacological and pharmacological approaches are recommended for treatment of lung disease, including smoking cessation, bronchodilators or supplemental oxygen as needed. Specific augmentation of AAT levels with regular purified AAT infusions has been found to slow lung function decline and emphysema progression in patients with moderate airflow obstruction and severely low serum AAT levels.

CONCLUSIONS

Improving primary care provider awareness and promoting regular reflex testing all COPD patients for AATD may significantly improve the care of COPD patients.

The pathological Trento variant of alpha-1-antitrypsin (E75V) shows nonclassical behaviour during polymerization

Severe alpha‐1‐antitrypsin deficiency (AATD) is most frequently associated with the alpha‐1‐antitrypsin (AAT) Z variant (E342K). ZZ homozygotes exhibit accumulation of AAT as polymers in the endoplasmic reticulum of hepatocytes. This protein deposition can lead to liver disease, with the resulting low circulating levels of AAT predisposing to early‐onset emphysema due to dysregulation of elastinolytic activity in the lungs. An increasing number of rare AAT alleles have been identified in patients with severe AATD, typically in combination with the Z allele. Here we report a new mutation (E75V) in a patient with severe plasma deficiency, which we designate Trento. In contrast to the Z mutant, Trento AAT was secreted efficiently when expressed in cellular models but showed compromised conformational stability. Polyacrylamide gel electrophoresis (PAGE) and ELISA‐based analyses of the secreted protein revealed the presence of oligomeric species with electrophoretic and immunorecognition profiles different from those of Z and S (E264V) AAT polymers, including reduced recognition by conformational monoclonal antibodies 2C1 and 4B12. This altered recognition was not due to direct effects on the epitope of the 2C1 monoclonal antibody which we localized between helices E and F. Structural analyses indicate the likely basis for polymer formation is the loss of a highly conserved stabilizing interaction between helix C and the posthelix I loop. These results highlight this region as important for maintaining native state stability and, when compromised, results in the formation of pathological polymers that are different from those produced by Z and S AAT.