α1-Antitrypsin reduces rhinovirus infection in primary human airway epithelial cells exposed to cigarette smoke

α‑1 Antitrypsin is a potential target of inflammation and immunomodulation (Review)

α‑1 Antitrypsin (AAT) is an acute phase protein encoded by the serine protease inhibitor family A member 1 gene. This multifunctional protein serves several roles, including anti‑inflammatory, antibacterial, antiapoptotic and immune regulatory functions. The primary role of AAT is to protect tissues and organs from protease‑induced damage due to its function as a serine protease inhibitor. AAT is associated with the development of lung inflammation, liver inflammation and immune‑mediated inflammatory diseases, which are influenced by environmental and genetic factors. For instance, AAT acts as an anti‑inflammatory protein to prevent and reverse type I diabetes. The present study briefly reviewed the molecular properties and mechanisms of AAT, as well as advances in the study of lung, liver and inflammatory diseases associated with AAT. The potential of AAT as a diagnostic and therapeutic target for inflammatory and immune‑mediated inflammatory diseases was reviewed. In addition, the damaging and protective effects of AAT, and its effects on organ function were discussed.

The Role of Inflammation in the Pathogenesis of Viral Respiratory Infections

Viral respiratory infections (VRIs) are a leading cause of morbidity and mortality worldwide, making them a significant public health concern. During infection, respiratory viruses, including Influenza virus, SARS-CoV-2, and respiratory syncytial virus (RSV), trigger an antiviral immune response, specifically boosting the inflammatory response that plays a critical role in their pathogenesis. The inflammatory response induced by respiratory viruses can be a double-edged sword since it can be initially induced to be antiviral and protective/reparative from virus-induced injuries. Still, it can also be detrimental to host cells and tissues. However, the mechanisms that differentiate the complex crosstalk between favorable host inflammatory responses and harmful inflammatory responses are poorly understood. This review explores the complex interplay between viral pathogens and the host immune response, mainly focusing on the role of inflammation in the pathogenesis of VRIs. We discuss how inflammation can both contain and exacerbate the progression of viral infections, highlighting potential therapeutic targets and emerging drugs for modulating the aberrant inflammatory responses during VRIs.

Type 1 diabetes contributes to combined pulmonary fibrosis and emphysema in male alpha 1 antitrypsin deficient mice

Type 1 diabetes (T1D) is a metabolic disease characterized by hyperglycemia and can affect multiple organs, leading to life-threatening complications. Increased prevalence of pulmonary disease is observed in T1D patients, and diabetes is a leading cause of comorbidity in several lung pathologies. A deficiency of alpha-1 antitrypsin (AAT) can lead to the development of emphysema. Decreased AAT plasma concentrations and anti-protease activity are documented in T1D patients. The objective of this study was to determine whether T1D exacerbates the progression of lung damage in AAT deficiency. First, pulmonary function testing (PFT) and histopathological changes in the lungs of C57BL/6J streptozotocin (STZ)-induced T1D mice were investigated 3 and 6 months after the onset of hyperglycemia. PFT demonstrated a restrictive pulmonary pattern in the lungs of STZ-injected mice, along with upregulation of mRNA expression of pro-fibrotic markers Acta2, Ccn2, and Fn1. Increased collagen deposition was observed 6 months after the onset of hyperglycemia. To study the effect of T1D on the progression of lung damage in AAT deficiency background, C57BL/6J AAT knockout (KO) mice were used. Control and STZ-challenged AAT KO mice did not show significant changes in lung function 3 months after the onset of hyperglycemia. However, histological examination of the lung demonstrated increased collagen accumulation and alveolar space enlargement in STZ-induced AAT KO mice. AAT pretreatment on TGF-β-stimulated primary lung fibroblasts reduced mRNA expression of pro-fibrotic markers ACTA2, CCN2, and FN1. Induction of T1D in AAT deficiency leads to a combined pulmonary fibrosis and emphysema (CPFE) phenotype in male mice.

Acute cigarette smoke exposure leads to higher viral infection in human bronchial epithelial cultures by altering interferon, glycolysis and GDF15-related pathways

BACKGROUND

Acute exacerbations of chronic inflammatory lung diseases, such as chronic obstructive pulmonary disease (COPD), are frequently associated with rhinovirus (RV) infections. Despite these associations, the pathogenesis of virus-induced exacerbations is incompletely understood. We aimed to investigate effects of cigarette smoke (CS), a primary risk factor for COPD, on RV infection in airway epithelium and identify novel mechanisms related to these effects.

METHODS

Primary bronchial epithelial cells (PBEC) from COPD patients and controls were differentiated by culture at the air-liquid interface (ALI) and exposed to CS and RV-A16. Bulk RNA sequencing was performed using samples collected at 6 and 24 h post infection (hpi), and viral load, mediator and L-lactate levels were measured at 6, 24 and 48hpi. To further delineate the effect of CS on RV-A16 infection, we performed growth differentiation factor 15 (GDF15) knockdown, L-lactate and interferon pre-treatment in ALI-PBEC. We performed deconvolution analysis to predict changes in the cell composition of ALI-PBEC after the various exposures. Finally, we compared transcriptional responses of ALI-PBEC to those in nasal epithelium after human RV-A16 challenge.

RESULTS

CS exposure impaired antiviral responses at 6hpi and increased viral replication at 24 and 48hpi in ALI-PBEC. At 24hpi, CS exposure enhanced expression of RV-A16-induced epithelial interferons, inflammation-related genes and CXCL8. CS exposure increased expression of oxidative stress-related genes, of GDF15, and decreased mitochondrial membrane potential. GDF15 knockdown experiments suggested involvement of this pathway in the CS-induced increase in viral replication. Expression of glycolysis-related genes and L-lactate production were increased by CS exposure, and was demonstrated to contribute to higher viral replication. No major differences were demonstrated between COPD and non-COPD-derived cultures. However, cellular deconvolution analysis predicted higher secretory cells in COPD-derived cultures at baseline.

CONCLUSION

Altogether, our findings demonstrate that CS exposure leads to higher viral infection in human bronchial epithelium by altering not only interferon responses, but likely also through a switch to glycolysis, and via GDF15-related pathways.

Severe COVID-19 Illness and α1-Antitrypsin Deficiency: COVID-AATD Study

BACKGROUND

Epidemiologic studies have reported that the geographical distribution of the prevalence of allelic variants of serine protein inhibitor-A1 (SERPINA1) and severe cases of COVID-19 were similar.

METHODS

A multicenter, cross-sectional, observational study to evaluate the frequency of alpha-1 antitrypsin deficiency (AATD) in patients with COVID-19 and whether it was associated with having suffered severe COVID-19.

RESULTS

2022 patients who had laboratory-confirmed SARS-CoV-2 infection. Mutations associated with AATD were more frequent in severe COVID versus non-severe (23% vs. 18.8%, p = 0.022). The frequency of Pi*Z was 37.8/1000 in severe COVID versus 17.5/1000 in non-severe, p = 0.001. Having an A1AT level below 116 was more frequent in severe COVID versus non-severe (29.5% vs. 23.1, p = 0.003). Factors associated with a higher likelihood of severe COVID-19 were being male, older, smoking, age-associated comorbidities, and having an A1AT level below 116 mg/dL [OR 1.398, p = 0.003], and a variant of the SERPINA1 gene that could affect A1AT protein [OR 1.294, p = 0.022].

CONCLUSIONS

These observations suggest that patients with AATD should be considered at a higher risk of developing severe COVID-19. Further studies are needed on the role of A1AT in the prognosis of SARS-CoV-2 infection and its possible therapeutic role.

Human Bronchial Epithelial Cell Culture Models for Cigarette Smoke and Vaping Studies

Despite the continuing public health efforts to stop or reduce smoking, cigarette smoke use remains popular in the youth and adult population. A recent surge in the use of electronic cigarette and vaping products has created another major health challenge in public health. There is an urgent need to use physiologically relevant models to study the health effect of smoking or vaping in human subjects. Airway diseases such as bronchitis (Landman et al., CMAJ 191:E1321-E1331, 2019; Goniewicz, et al. Harm Reduct J 17:91, 2020; Xie et al., JAMA Netw Open 3:e2020816, 2020) have been described in people who smoke, vape, or both. Here, we will describe methods to collect, expand, and culture human airway epithelial cells from endobronchial brushings and expose these cells cultured at the air-liquid interface to cigarette smoke or electronic cigarette vapor.

α1-Antitrypsin: Key Player or Bystander in Acute Respiratory Distress Syndrome?

Acute respiratory distress syndrome is characterized by hypoxemia, altered alveolar-capillary permeability, and neutrophil-dominated inflammatory pulmonary edema. Despite decades of research, an effective drug therapy for acute respiratory distress syndrome remains elusive. The ideal pharmacotherapy for acute respiratory distress syndrome should demonstrate antiprotease activity and target injurious inflammatory pathways while maintaining host defense against infection. Furthermore, a drug with a reputable safety profile, low possibility of off-target effects, and well-known pharmacokinetics would be desirable. The endogenous 52-kd serine protease α1-antitrypsin has the potential to be a novel treatment option for acute respiratory distress syndrome. The main function of α1-antitrypsin is as an antiprotease, targeting neutrophil elastase in particular. However, studies have also highlighted the role of α1-antitrypsin in the modulation of inflammation and bacterial clearance. In light of the current SARS-CoV-2 pandemic, the identification of a treatment for acute respiratory distress syndrome is even more pertinent, and α1-antitrypsin has been implicated in the inflammatory response to SARS-CoV-2 infection.

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 β-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.

Alpha-1-antitrypsin: A possible host protective factor against Covid-19

Understanding Covid-19 pathophysiology is crucial for a better understanding of the disease and development of more effective treatments. Alpha-1-antitrypsin (A1AT) is a constitutive tissue protector with antiviral and anti-inflammatory properties. A1AT inhibits SARS-CoV-2 infection and two of the most important proteases in the pathophysiology of Covid-19: the transmembrane serine protease 2 (TMPRSS2) and the disintegrin and metalloproteinase 17 (ADAM17). It also inhibits the activity of inflammatory molecules, such as IL-8, TNF-α, and neutrophil elastase (NE). TMPRSS2 is essential for SARS-CoV-2-S protein priming and viral infection. ADAM17 mediates ACE2, IL-6R, and TNF-α shedding. ACE2 is the SARS-CoV-2 entry receptor and a key component for the balance of the renin-angiotensin system, inflammation, vascular permeability, and pulmonary homeostasis. In addition, clinical findings indicate that A1AT levels might be important in defining Covid-19 outcomes, potentially partially explaining associations with air pollution and with diabetes. In this review, we focused on the interplay between A1AT with TMPRSS2, ADAM17 and immune molecules, and the role of A1AT in the pathophysiology of Covid-19, opening new avenues for investigating effective treatments.

Rhinovirus and Innate Immune Function of Airway Epithelium

Airway epithelial cells, which lines the respiratory mucosa is in direct contact with the environment. Airway epithelial cells are the primary target for rhinovirus and other inhaled pathogens. In response to rhinovirus infection, airway epithelial cells mount both pro-inflammatory responses and antiviral innate immune responses to clear the virus efficiently. Some of the antiviral responses include the expression of IFNs, endoplasmic reticulum stress induced unfolded protein response and autophagy. Airway epithelial cells also recruits other innate immune cells to establish antiviral state and resolve the inflammation in the lungs. In patients with chronic lung disease, these responses may be either defective or induced in excess leading to deficient clearing of virus and sustained inflammation. In this review, we will discuss the mechanisms underlying antiviral innate immunity and the dysregulation of some of these mechanisms in patients with chronic lung diseases.

Long-term safety of α-1 antitrypsin therapy in children and adolescents with Type 1 diabetes

Promising findings of α-1 antitrypsin (AAT) intervention in mice models of Type 1 diabetes (T1D) led researchers to investigate AAT as a therapeutic modality for β-cell preservation in recent-onset T1D patients. Our prospective, open-label Phase I/II extension study demonstrated that the administration of multiple repeated AAT infusions (up to 36) to AAT-sufficient pediatric T1D patients is safe and well-tolerated. Long-term surveillance of participants (up to 5 years) from diabetes onset revealed normal growth and pubertal progression through adolescence to attainment of full puberty and near adult height. No serious adverse events, clinical or laboratory abnormalities were reported. Given its safety profile, AAT may be an individualized-tailored innovative immunotherapy in AAT-sufficient pediatric patients with diverse immune-related medical conditions. ClinicalTrials.gov Identifier: NCT01661192.

Immunoproteasomes as a novel antiviral mechanism in rhinovirus-infected airways

Rhinovirus (RV) infection is involved in acute exacerbations of asthma and chronic obstructive pulmonary disease (COPD). RV primarily infects upper and lower airway epithelium. Immunoproteasomes (IP) are proteolytic machineries with multiple functions including the regulation of MHC class I antigen processing during viral infection. However, the role of IP in RV infection has not been explored. We sought to investigate the expression and function of IP during airway RV infection. Primary human tracheobronchial epithelial (HTBE) cells were cultured at air-liquid interface (ALI) and treated with RV16, RV1B, or interferon (IFN)-λ in the absence or presence of an IP inhibitor (ONX-0914). IP gene (i.e. LMP2) deficient mouse tracheal epithelial cells (mTECs) were cultured for the mechanistic studies. LMP2-deficient mouse model was used to define the in vivo role of IP in RV infection. IP subunits LMP2 and LMP7, antiviral genes MX1 and OAS1 and viral load were measured. Both RV16 and RV1B significantly increased the expression of LMP2 and LMP7 mRNA and proteins, and IFN-λ mRNA in HTBE cells. ONX-0914 down-regulated MX1 and OAS1, and increased RV16 load in HTBE cells. LMP2-deficient mTECs showed a significant increase in RV1B load compared with the wild-type (WT) cells. LMP2-deficient (compared with WT) mice increased viral load and neutrophils in bronchoalveolar lavage (BAL) fluid after 24 h of RV1B infection. Mechanistically, IFN-λ induction by RV infection contributed to LMP2 and LMP7 up-regulation in HTBE cells. Our data suggest that IP are induced during airway RV infection, which in turn may serve as an antiviral and anti-inflammatory mechanism.

Antiviral drug screening by assessing epithelial functions and innate immune responses in human 3D airway epithelium model

Respiratory viral infections cause mild to severe diseases, such as common cold, bronchiolitis and pneumonia and are associated with substantial burden for society. To test new molecules for shortening, alleviating the diseases or to develop new therapies, relevant human in vitro models are mandatory. MucilAir™, a human standardized air-liquid interface 3D airway epithelial culture holds in vitro specific mechanisms to counter invaders comparable to the in vivo situation, such as mucus production, mucociliary clearance, and secretion of defensive molecules. The objective of this study was to test the relevance of such a model for the discovery and validation of antiviral drugs. Fully differentiated 3D nasal epithelium cultures were inoculated with picornaviruses, a coronavirus and influenza A viruses in the absence or in the presence of reference antiviral drugs. Results showed that, rupintrivir efficiently inhibits the replication of respiratory picornaviruses in a dose dependent manner and prevents the impairment of the mucociliary clearance. Similarly, oseltamivir reduced the replication of influenza A viruses in a dose dependent manner and prevented the impairment of the epithelial barrier function and cytotoxicity until 4 days of infection. In addition we found that Rhinovirus B14, C15 and influenza A(H1N1) induce significant increase of β Defensins 2 and Cathelicidin release with different time course. These results reveal that a large panel of epithelial functions is modified upon viral infection and validate MucilAir™ as a pertinent tool for pre-clinical antiviral drug testing.

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Reference antivirals inhibit in a dose-dependent manner the respiratory virus production in MucilAir™.

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Respiratory viruses induce specific antimicrobial peptide expression and functional changes in MucilAir™.

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Antivirals prevent virus-induced dysfunctions, the disruption of epithelial barrier and the decrease of mucociliary clearance.

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MucilAir™ is a suitable model to produce clinical respiratory virus isolates and to perform antiviral drugs screening.

A1AT polymorphisms may be associated with clinical characteristics of retrovirus infections in a mixed ethnic population from the Brazilian Amazon region

OBJECTIVES

This study investigated the association of alpha-1-antrypsin deficiency (A1AT; S and Z polymorphisms) with HIV-1 and HTLV-1 infection.

METHODS

Blood samples from 201 HIV-1-infected and 115 HTLV-1-infected individuals were examined and compared with those from 300 healthy controls. Genotyping of A1AT (S and Z) and quantification of plasma viral load were performed using RT-PCR, and the CD4+/CD8+ T-cell count was determined by flow cytometry.

RESULTS

The wild-type MM genotype showed the highest frequency in each of the three groups investigated. SS and ZZ homozygous genotypes (variants) were observed only among HTLV-1 patients and controls, respectively. Genotype MS was significantly less frequent in HTLV-1-positive persons than in controls. Statistically significant differences were observed when comparing genotype frequencies between symptomatic and asymptomatic HTLV-1-infected persons. The distribution of plasma HIV-1 viral load among individuals with different genotypes of A1AT polymorphism also differed significantly.

CONCLUSIONS

The results suggest that A1AT polymorphisms may be associated with human retrovirus infections when dealing with an ethnically mixed population from the Amazon region of Brazil.

Rhinovirus and COPD airway epithelium

Chronic Obstructive Pulmonary Disease (COPD) is characterized by irreversible airflow limitation. It is a global disease and expected to be the third leading cause of death. Respiratory exacerbations are associated with increased mortality and morbidity in this patient population. Respiratory viruses were isolated from at least 30 to 50% of the infectious respiratory COPD exacerbations with rhinovirus being most commonly isolated pathogen. Although rhinovirus does not cause airway epithelial damage like influenza and other respiratory viruses, it may further impair innate immunity of airway epithelium, which is the first line of defense in the lungs. This may increase susceptibility to secondary bacterial infections leading to progression of lung disease. Currently, there arc no therapies available to treat rhinovirus infection in COPD and therefore understanding the mechanisms underlying RV pathogenesis in COPD is essential to identify molecular target to develop new therapeutic strategies. Quercetin, a plant polyphenol, which modulates innate immunity and effectively blocks viral replication may be useful in treating rhinovirus associated COPD exacerbations.

MUC18 Regulates Lung Rhinovirus Infection and Inflammation

Background

MUC18 is upregulated in the lungs of asthma and COPD patients. It has been shown to have pro-inflammatory functions in cultured human airway epithelial cells during viral infections and in mice during lung bacterial infections. However, the in vivo role of MUC18 in the context of viral infections remains poorly understood. The goal of this study is to define the in vivo function of MUC18 during respiratory rhinovirus infection.

Methods

Muc18 wild-type (WT) and knockout (KO) mice were infected with human rhinovirus 1B (HRV-1B) and sacrificed after 1 day to determine the inflammatory and antiviral responses. To examine the direct effects of Muc18 on viral infection, tracheal epithelial cells isolated from WT and KO mice were grown under air-liquid interface and infected with HRV-1B. Finally, siRNA mediated knockdown of MUC18 was performed in human airway epithelial cells (AECs) to define the impact of MUC18 on human airway response to HRV-1B.

Results

Both viral load and neutrophilic inflammation were significantly decreased in Muc18 KO mice compared to WT mice. In the in vitro setting, viral load was significantly lower and antiviral gene expression was higher in airway epithelial cells of Muc18 KO mice than the WT mice. Furthermore, in MUC18 knockdown human AECs, viral load was decreased and antiviral gene expression was increased compared to controls.

Conclusions

Our study is the first to demonstrate MUC18’s pro-inflammatory and pro-viral function in an in vivo mouse model of rhinovirus infection.