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.

Recombinant Alpha-1 Antitrypsin-Fc Fusion Protein INBRX-101 in Adults With Alpha-1 Antitrypsin Deficiency: A Phase 1 Study.

Background: Alpha-1 antitrypsin deficiency (AATD) is characterized by low alpha-1 antitrypsin (AAT) levels, predisposing individuals to lung disease. The standard of care, plasma-derived AAT (pdAAT), is delivered as weekly infusions to maintain serum AAT concentrations ≥11µM (≈50% of those in healthy individuals). INBRX-101, a recombinant human AAT-Fc fusion protein, was designed to have a longer half-life and achieve higher AAT levels than pdAAT. Methods: In this phase 1 dose-escalation study (N=31), adults with AATD received 1 dose (part 1) or 3 doses (part 2) of 10 (part 1), 40, 80, or 120mg/kg INBRX-101 every 3 weeks (Q3W) via intravenous infusion. The primary endpoint was safety and tolerability. Secondary endpoints were pharmacokinetics (PK), pharmacodynamics (PD), and immunogenicity of INBRX-101. Results: INBRX-101 was well tolerated. Most treatment-emergent adverse events were grade ≤2. In part 2 (n=18; each dose, n=6), dose-related increases in serum functional AAT (fAAT) were observed; mean fAAT levels remained above the 21 µM target for up to 4 weeks after the final dose in the 120-mg/kg cohort. Antidrug antibodies had no meaningful impact on PK or PD. INBRX-101 was detected in pulmonary epithelial lining fluid (PELF) from all patients assessed (n=11), and PELF fAAT increased after dosing. PK/PD modeling projected steady-state serum fAAT ≥21µM at 120 mg/kg Q3W (average concentration ≈43µM; trough concentration ≈28µM) and Q4W (≈34µM; ≈21µM). Conclusion: The favorable safety profile and ability to maintain serum fAAT levels >21µM with extended-interval dosing, support a phase 2 trial evaluating Q3W and Q4W dosing of INBRX-101.

Development of a risk score to increase detection of severe alpha-1 antitrypsin deficiency.

Background: Alpha-1 antitrypsin deficiency (AATD) is an under-recognised genetic cause of chronic obstructive lung disease, and many fewer cases than estimated have been identified. Can a reported respiratory and hepatic disease history from a large AATD testing database be used to stratify a person's risk of severe AATD? Methods: We analysed data extracted from the AATD National Detection Program. Demographics and medical history were evaluated to predict AATD PI*ZZ genotype. Logistic regression and integer programming models identified predictors and obtained risk scores. These were internally validated on a subset of the data. Results: Out of 301 343 subjects, 1529 (0.5%) had PI*ZZ genotype. Predictors of severe AATD were asthma, bronchitis, emphysema, allergies, bronchiectasis, family history of AATD, cirrhosis, hepatitis and history of abnormal liver function tests. The derived model establishes a subject's risk of severe AATD, and scores ≥0 had an estimated risk of 0.41%, sensitivity 84.62% and specificity 24.32%. A model simulating guideline recommendations had an estimated risk of 0.51% with a sensitivity of 37.98% and specificity 46.60%. By recommending screening for scores ≥0, we estimate that more subjects would be screened (75.7% versus 53.4%) and detected (84.6% versus 58.2%) compared to a guideline-simulated model. Conclusion: This medical history risk model is a useful predictive tool to detect subjects at greater risk of having severe AATD and improves sensitivity of detection. Scores <0 are at lower risk and may need not be screened; testing is recommended for scores ≥0 and consistent with current guidelines.

Lung microhaemorrhage drives oxidative/inflammatory damage in α1-antitrypsin deficiency.

Background: Animal models using intratracheal instillation show that elastase, unopposed by α1-antitrypsin (AAT), causes alveolar damage and haemorrhage associated with emphysematous changes. The aim of the present study was to characterise any relationship between alveolar haemorrhage and human AAT deficiency (AATD) using bronchoalveolar lavage (BAL) and lung explant samples from AATD subjects. Methods: BAL samples (17 patients, 15 controls) were evaluated for free haem (iron protoporphyrin IX) and total iron concentrations. Alveolar macrophage activation patterns were assessed using RNA sequencing and validated in vitro using haem-stimulated, monocyte-derived macrophages. Lung explants (seven patients, four controls) were assessed for iron sequestration protein expression patterns using Prussian blue stain and ferritin immunohistochemistry, as well as ferritin iron imaging and elemental analysis by transmission electron microscopy. Tissue oxidative damage was assessed using 8-hydroxy-2'-deoxyguanosine immunohistochemistry. Results: BAL collected from AATD patients showed significantly elevated free haem and total iron concentrations. Alveolar and interstitial macrophages in AATD explants showed elevated iron and ferritin accumulation in large lysosomes packed by iron oxide cores with degraded ferritin protein cages. BAL macrophage RNA sequencing showed innate pro-inflammatory activation, replicated in vitro by haemin exposure, which also triggered reactive oxygen species generation. AATD explants showed massive oxidative DNA damage in both lung epithelial cells and macrophages. Conclusions: BAL and tissue markers of alveolar haemorrhage, together with molecular and cellular evidence of macrophage innate pro-inflammatory activation and oxidative damage, are consistent with free haem stimulation. Overall, this initial study provides evidence for a pathogenetic role of elastase-induced alveolar haemorrhage in AATD emphysema.

Severe COVID-19 After Recent Heart Transplantation Complicated by Allograft Dysfunction.

A 50-year-old male presented with atrial flutter 25 days after heart and kidney transplantation. Rejection was excluded, but he developed severe COVID-19 infection with cardiac allograft dysfunction. Despite continued corticosteroid and tacrolimus therapy, he remained aviremic. Respiratory and myocardial functions recovered after a week of mechanical ventilation. The cardiomyopathy was stress induced. (Level of Difficulty: Advanced.).

Intravenous Alpha-1 Antitrypsin Therapy for Alpha-1 Antitrypsin Deficiency: The Current State of the Evidence.

Alpha-1 antitrypsin deficiency (AATD) is a largely monogenetic disorder associated with a high risk for the development of chronic obstructive pulmonary disease (COPD) and cirrhosis. Intravenous alpha-1 antitrypsin (AAT) therapy has been available for the treatment of individuals with AATD and COPD since the late 1980s. Initial Food and Drug Administration (FDA) approval was granted based on biochemical efficacy. Following its approval, the FDA, scientific community and third-party payers encouraged manufacturers of AAT therapy to determine its clinical efficacy. This task has proved challenging because AATD is a rare, orphan disorder comprised of individuals who are geographically dispersed and infrequently identified. In addition, robust clinical trial outcomes have been lacking until recently. This review provides an update on the evidence for the clinical efficacy of intravenous AAT therapy for patients with AATD-related emphysema.

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.