Tollip SNP rs5743899 modulates human airway epithelial responses to rhinovirus infection

Associations between genetic variants of Toll-interacting proteins and interstitial lung diseases: a systematic review and meta-analysis

BACKGROUND

Genetic polymorphisms in Toll-interacting protein (TOLLIP) have been documented in relation to clinical manifestations of interstitial lung disease (ILD). Nevertheless, the findings across studies present inconsistencies. The present meta-analysis endeavors to elucidate the nexus between genetic variations in TOLLIP and the onset and prognosis of interstitial lung disease (ILD), with the overarching aim of providing insight into the pathophysiological underpinnings of ILD.

METHOD

This systematic review was registered in PROSPERO. The OVID MEDLINE, OVID EMBASE, and Web of Science electronic databases were searched.

RESULTS

Fourteen studies with a total of 4821 cases and 9765 controls were examined. The final TOLLIP variants to be included in this meta-analysis were rs5743890, rs111521887, and rs3750920. There were significantly fewer TOLLIP rs5743890 minor allele C carriers among individuals with interstitial lung disease (ILD) than among those without this condition (11.42% vs. 18.92%). Conversely, patients with ILD exhibited higher frequencies of rs111521887 minor allele G carriers (28.92% vs. 22.44%) and rs3750920 minor allele T carriers (40.06% vs. 34.00%). A potential association between rs5743890_C and a reduced incidence of ILD was plausible (p = 0.04, OR = 0.72, 95% CI = 0.53-0.99). Furthermore, a stratified analysis revealed that rs5743890_C was significantly associated with a decreased risk of IPF (p = 0.004, OR = 0.62, 95% CI = 0.44-0.86). There was a significant correlation between susceptibility to ILD and rs111521887 G (p < 0.00001, OR = 1.48, 95% CI = 1.33-1.65) and rs3750920 T (p < 0.00001, OR = 1.34, 95% CI = 1.26-1.44). The survival of IPF patients was correlated with the TOLLIP rs5743890 SNP, and patients with the rs5743890_C genotype had worse survival (p = 0.02, HR = 1.59, 95% CI = 1.07-2.36).

CONCLUSION

This study showed that rs5743890_C was associated with a lower incidence of ILD and a worse survival rate in patients with IPF. Rs111521887_G and rs3750920_T were found to be associated with an elevated risk of ILD incidence, while no significant association was observed with ILD prognosis. Furthermore, studies are warranted to validate our results and assess the effects of TOLLIP genetic variants on ILD.

TOLLIP and MUC5B modulate the effect of ambient NO2 on respiratory symptoms in infancy

BACKGROUND

Current knowledge suggests that the gene region containing MUC5B and TOLLIP plays a role in airway defence and airway inflammation, and hence respiratory disease. It is also known that exposure to air pollution increases susceptibility to respiratory disease. We aimed to study whether the effect of air pollutants on the immune response and respiratory symptoms in infants may be modified by polymorphisms in MUC5B and TOLLIP genes.

METHODS

359 healthy term infants from the prospective Basel-Bern Infant Lung Development (BILD) birth cohort were included in the study. The main outcome was the score of weekly assessed respiratory symptoms in the first year of life. Using the candidate gene approach, we selected 10 single nucleotide polymorphisms (SNPs) from the MUC5B and TOLLIP regions. Nitrogen dioxide (NO2) and particulate matter ≤10 μm in aerodynamic diameter (PM10) exposure was estimated on a weekly basis. We used generalised additive mixed models adjusted for known covariates. To validate our results in vitro, cells from a lung epithelial cell line were downregulated in TOLLIP expression and exposed to diesel particulate matter (DPM) and polyinosinic-polycytidylic acid.

RESULTS

Significant interaction was observed between modelled air pollution (weekly NO2 exposure) and 5 SNPs within MUC5B and TOLLIP genes regarding respiratory symptoms as outcome: E.g., infants carrying minor alleles of rs5744034, rs3793965 and rs3750920 (all TOLLIP) had an increased risk of respiratory symptoms with increasing NO2 exposure. In vitro experiments showed that cells downregulated for TOLLIP react differently to environmental pollutant exposure with DPM and viral stimulation.

CONCLUSION

Our findings suggest that the effect of air pollution on respiratory symptoms in infancy may be influenced by the genotype of specific SNPs from the MUC5B and TOLLIP regions. For validation of the findings, we provided in vitro evidence for the interaction of TOLLIP with air pollution.

Single nucleotide polymorphism of Notch1 gene rs3124599 allele is associated with the severity of CVA6-related HFMD in the Chinese Han population

BACKGROUND

There is evidence suggesting that Notch1 signaling pathway contributes to the development of hand, foot, and mouth disease (HFMD); however, the role of Notch1 gene polymorphisms in the severity of coxsackievirus A6 (CVA6)-related HFMD remains unclear. This study aimed to investigate the correlation between Notch1 gene polymorphisms and the severity of CVA6-related HFMD.

METHODS

A total of 196 patients (Chinese Han population) diagnosed with CVA6-related HFMD through nucleic acid testing were included in this study. Among them, 97 patients were classified as severe cases, while 99 cases were categorized as mild. The mRNA levels of Notch1 in the peripheral blood leukocytes of HFMD patients were detected by quantitative real-time polymerase chain reaction (qRT-PCR), and the polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) technique was utilized for genotyping of rs3124599, rs3124603, and rs3124591.

RESULTS

The frequencies of rs3124599 alleles were G (39.0%) and A (61.0%), while the frequencies of rs3124599 genotypes were GG (12.2%), GA (53.6%), and AA (34.2%), respectively. In the recessive model, the frequency of rs3124599 AA genotypes significantly increased in severe patients, compared to mild patients (P < 0.05). Due to the low frequency of alleles for rs3124591 and rs3124603 in patients, as well as the absence of any difference in their distribution between the two groups (P > 0.05), no additional statistical analysis was performed. After adjusting for age and sex, patients with rs3124599 AA genotype had a significantly higher risk of severe HFMD in comparison to G allele carriers (GA/GG), with an odds ratio (95% confidence interval) of 2.010 (1.094, 3.691). Meanwhile, the mRNA levels of Notch1 were found to be significantly higher in severe patients compared to mild patients (P < 0.05), and a positive correlation was observed between Notch1 mRNA levels and the peripheral blood monocyte count (r = 0.42, P < 0.001). Additionally, there were significant differences observed in Notch1 mRNA levels and peripheral blood monocyte counts between patients with the AA genotype of rs3124599 and those with the GA genotype or G allele carriers (P < 0.05).

CONCLUSION

In the Chinese Han population, there is a strong correlation between the Notch1 rs3124599 allele and the severity of CVA6-related HFMD. This correlation may be attributed to genetic polymorphism of rs3124599 regulating Notch1 transcription levels. These findings reveal the important role of Notch1 gene polymorphism in CVA6 infection, establishing a scientific foundation for the precise control of severe HFMD.

Cooperation of immune regulators Tollip and surfactant protein A inhibits influenza A virus infection in mice

BACKGROUND

Influenza A virus (IAV) infection is a significant risk factor for respiratory diseases, but the host defense mechanisms against IAV remain to be defined. Immune regulators such as surfactant protein A (SP-A) and Toll-interacting protein (Tollip) have been shown to be involved in IAV infection, but whether SP-A and Tollip cooperate in more effective host defense against IAV infection has not been investigated.

METHODS

Wild-type (WT), Tollip knockout (KO), SP-A KO, and Tollip/SP-A double KO (dKO) mice were infected with IAV for four days. Lung macrophages were isolated for bulk RNA sequencing. Precision-cut lung slices (PCLS) from WT and dKO mice were pre-treated with SP-A and then infected with IAV for 48 h.

RESULTS

Viral load was significantly increased in bronchoalveolar lavage (BAL) fluid of dKO mice compared to all other strains of mice. dKO mice had significantly less recruitment of neutrophils into the lung compared to Tollip KO mice. SP-A treatment of PCLS enhanced expression of TNF and reduced viral load in dKO mouse lung tissue. Pathway analysis of bulk RNA sequencing data suggests that macrophages from IAV-infected dKO mice reduced expression of genes involved in neutrophil recruitment, IL-17 signaling, and Toll-like receptor signaling.

CONCLUSIONS

Our data suggests that both Tollip and SP-A are essential for the lung to exert more effective innate defense against IAV infection.

Tollip deficiency exaggerates airway type 2 inflammation in mice exposed to allergen and influenza A virus: role of the ATP/IL-33 signaling axis

Toll-interacting protein (Tollip) is a negative regulator of the pro-inflammatory response to viruses, including influenza A virus (IAV). Genetic variation of Tollip has been associated with reduced airway epithelial Tollip expression and poor lung function in patients with asthma. Whether Tollip deficiency exaggerates type 2 inflammation (e.g., eosinophils) and viral infection in asthma remains unclear. We sought to address this critical, but unanswered question by using a Tollip deficient mouse asthma model with IAV infection. Further, we determined the underlying mechanisms by focusing on the role of the ATP/IL-33 signaling axis. Wild-type and Tollip KO mice were intranasally exposed to house dust mite (HDM) and IAV with or without inhibitors for IL-33 (i.e., soluble ST2, an IL-33 decoy receptor) and ATP signaling (i.e., an antagonist of the ATP receptor P2Y13). Tollip deficiency amplified airway type 2 inflammation (eosinophils, IL-5, IL-13 and mucins), and the release of ATP and IL-33. Blocking ATP receptor P2Y13 decreased IL-33 release during IAV infection in HDM-challenged Tollip KO mice. Furthermore, soluble ST2 attenuated airway eosinophilic inflammation in Tollip KO mice treated with HDM and IAV. HDM challenges decreased lung viral load in wild-type mice, but Tollip deficiency reduced the protective effects of HDM challenges on viral load. Our data suggests that during IAV infection, Tollip deficiency amplified type 2 inflammation and delayed viral clearance, in part by promoting ATP signaling and subsequent IL-33 release. Our findings may provide several therapeutic targets, including ATP and IL-33 signaling inhibition for attenuating excessive airway type 2 inflammation in human subjects with Tollip deficiency and IAV infection.

Autophagopathies: from autophagy gene polymorphisms to precision medicine for human diseases

At a time when complex diseases affect globally 280 million people and claim 14 million lives every year, there is an urgent need to rapidly increase our knowledge into their underlying etiologies. Though critical in identifying the people at risk, the causal environmental factors (microbiome and/or pollutants) and the affected pathophysiological mechanisms are not well understood. Herein, we consider the variations of autophagy-related (ATG) genes at the heart of mechanisms of increased susceptibility to environmental stress. A comprehensive autophagy genomic resource is presented with 263 single nucleotide polymorphisms (SNPs) for 69 autophagy-related genes associated with 117 autoimmune, inflammatory, infectious, cardiovascular, neurological, respiratory, and endocrine diseases. We thus propose the term 'autophagopathies' to group together a class of complex human diseases the etiology of which lies in a genetic defect of the autophagy machinery, whether directly related or not to an abnormal flux in autophagy, LC3-associated phagocytosis, or any associated trafficking. The future of precision medicine for common diseases will lie in our ability to exploit these ATG SNP x environment relationships to develop new polygenetic risk scores, new management guidelines, and optimal therapies for afflicted patients.Abbreviations: ATG, autophagy-related; ALS-FTD, amyotrophic lateral sclerosis-frontotemporal dementia; ccRCC, clear cell renal cell carcinoma; CD, Crohn disease; COPD, chronic obstructive pulmonary disease; eQTL, expression quantitative trait loci; HCC, hepatocellular carcinoma; HNSCC, head and neck squamous cell carcinoma; GTEx, genotype-tissue expression; GWAS, genome-wide association studies; LAP, LC3-associated phagocytosis; LC3-II, phosphatidylethanolamine conjugated form of LC3; LD, linkage disequilibrium; LUAD, lung adenocarcinoma; MAF, minor allele frequency; MAP1LC3/LC3: microtubule associated protein 1 light chain 3; NSCLC, non-small cell lung cancer; OS, overall survival; PtdIns3K CIII, class III phosphatidylinositol 3 kinase; PtdIns3P, phosphatidylinositol-3-phosphate; SLE, systemic lupus erythematosus; SNPs, single-nucleotide polymorphisms; mQTL, methylation quantitative trait loci; ULK, unc-51 like autophagy activating kinase; UTRs, untranslated regions; WHO, World Health Organization.

Suppression of ACE2 SUMOylation protects against SARS-CoV-2 infection through TOLLIP-mediated selective autophagy

In addition to investigating the virology of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), discovering the host–virus dependencies are essential to identify and design effective antiviral therapy strategy. Here, we report that the SARS-CoV-2 entry receptor, ACE2, conjugates with small ubiquitin-like modifier 3 (SUMO3) and provide evidence indicating that prevention of ACE2 SUMOylation can block SARS-CoV-2 infection. E3 SUMO ligase PIAS4 prompts the SUMOylation and stabilization of ACE2, whereas deSUMOylation enzyme SENP3 reverses this process. Conjugation of SUMO3 with ACE2 at lysine (K) 187 hampers the K48-linked ubiquitination of ACE2, thus suppressing its subsequent cargo receptor TOLLIP-dependent autophagic degradation. TOLLIP deficiency results in the stabilization of ACE2 and elevated SARS-CoV-2 infection. In conclusion, our findings suggest selective autophagic degradation of ACE2 orchestrated by SUMOylation and ubiquitination as a potential way to combat SARS-CoV-2 infection.

SARS- CoV-2 hijacks ACE2 for cell entry. Here, the authors report that dynamic SUMOylation modulates the TOLLIP-directed selective autophagic degradation of ACE2 and suggest SUMOylation inhibition as a potential intervention against SARS-CoV-2 infection.

Tollip Inhibits IL-33 Release and Inflammation in Influenza A Virus-Infected Mouse Airways

Respiratory influenza A virus (IAV) infection continues to pose significant challenges in healthcare of human diseases including asthma. IAV infection in mice was shown to increase IL-33, a key cytokine in driving airway inflammation in asthma, but how IL-33 is regulated during viral infection remains unclear. We previously found that a genetic mutation in Toll-interacting protein (Tollip) was linked to less airway epithelial Tollip expression, increased neutrophil chemokines, and lower lung function in asthma patients. As Tollip is involved in maintaining mitochondrial function, and mitochondrial stress may contribute to extracellular ATP release and IL-33 secretion, we hypothesized that Tollip downregulates IL-33 secretion via inhibiting ATP release during IAV infection. Wild-type and Tollip knockout (KO) mice were infected with IAV and treated with either an ATP converter apyrase or an IL-33 decoy receptor soluble ST2 (sST2). KO mice significantly lost more body weight and had increased extracellular ATP, IL-33 release, and neutrophilic inflammation. Apyrase treatment reduced extracellular ATP levels, IL-33 release, and neutrophilic inflammation in Tollip KO mice. Excessive lung neutrophilic inflammation in IAV-infected Tollip KO mice was reduced by sST2, which was coupled with less IL-33 release. Our data suggest that Tollip inhibits IAV infection, potentially by inhibiting extracellular ATP release and reducing IL-33 activation and lung inflammation. In addition, sST2 may serve as a potential therapeutic approach to mitigate respiratory viral infection in human subjects with Tollip deficiency.

Tollip interaction with STAT3: a novel mechanism to regulate human airway epithelial responses to type 2 cytokines

BACKGROUND

Toll-interacting protein (Tollip) is one of the key negative regulators in host innate immunity. Genetic variation of Tollip has been associated with less Tollip expression and poor lung function in asthmatic patients, but little is known about the role of Tollip in human airway type 2 inflammatory response, a prominent feature in allergic asthma.

OBJECTIVE

Our goal was to determine the role and underlying mechanisms of Tollip in human airway epithelial responses such as eotaxin to type 2 cytokine IL-13.

METHODS

Tollip deficient primary human airway epithelial cells from 4 healthy donors were generated by the gene knockdown approach and stimulated with IL-13 to measure activation of transcription factor STAT3, and eotaxin-3, an eosinophilic chemokine.

RESULTS

Following IL-13 treatment, Tollip deficient cells had significantly higher levels of STAT3 activation and eotaxin-3 than the scrambled control counterpart, which was reduced by a STAT3 inhibitor. Interaction between Tollip and STAT3 proteins was identified by co-immunoprecipitation.

CONCLUSION

Our results, for the first time, suggest that Tollip inhibits excessive eotaxin-3 induction by IL-13, in part through the interaction and inhibition of STAT3. These findings lend evidence to the potential of a STAT3 inhibitor as a therapeutic target, especially for type 2 inflammation-high asthmatics with Tollip deficiency.

Susceptibility of Human Airway Tissue Models Derived From Different Anatomical Sites to Bordetella pertussis and Its Virulence Factor Adenylate Cyclase Toxin

To study the interaction of human pathogens with their host target structures, human tissue models based on primary cells are considered suitable. Complex tissue models of the human airways have been used as infection models for various viral and bacterial pathogens. The Gram-negative bacterium Bordetella pertussis is of relevant clinical interest since whooping cough has developed into a resurgent infectious disease. In the present study, we created three-dimensional tissue models of the human ciliated nasal and tracheo-bronchial mucosa. We compared the innate immune response of these models towards the B. pertussis virulence factor adenylate cyclase toxin (CyaA) and its enzymatically inactive but fully pore-forming toxoid CyaA-AC^-. Applying molecular biological, histological, and microbiological assays, we found that 1 µg/ml CyaA elevated the intracellular cAMP level but did not disturb the epithelial barrier integrity of nasal and tracheo-bronchial airway mucosa tissue models. Interestingly, CyaA significantly increased interleukin 6, interleukin 8, and human beta defensin 2 secretion in nasal tissue models, whereas tracheo-bronchial tissue models were not significantly affected compared to the controls. Subsequently, we investigated the interaction of B. pertussis with both differentiated primary nasal and tracheo-bronchial tissue models and demonstrated bacterial adherence and invasion without observing host cell type-specific significant differences. Even though the nasal and the tracheo-bronchial mucosa appear similar from a histological perspective, they are differentially susceptible to B. pertussis CyaA in vitro. Our finding that nasal tissue models showed an increased innate immune response towards the B. pertussis virulence factor CyaA compared to tracheo-bronchial tissue models may reflect the key role of the nasal airway mucosa as the first line of defense against airborne pathogens.

Toll-interacting protein polymorphisms in viral bronchiolitis outcomes

BACKGROUND

Toll-interacting protein is a key factor in regulating innate immunity responses via gatekeeping Toll-like receptors. Genetic variance in innate immunity has been linked with susceptibility to infections. Children with viral bronchiolitis in infancy are at increased risk of later asthma. The aim was to evaluate the role of toll-interacting protein gene point mutations in severity of bronchiolitis and subsequent risk of asthma.

METHODS

Infants less than 6 months old were recruited during hospitalization due to bronchiolitis. In all, 166 children were prospectively followed up to age of 1.5, 6, and 11 years. Clinical data on viral etiology and severity markers, and further post-bronchiolitis asthma and lung function outcomes were compared with genetic differences in two single-nucleotide point mutations rs116938768 and rs5743854 in the toll-interacting protein gene.

RESULTS

Toll-interacting protein rs116938768 or rs5743854 did not show significant associations with severity markers or viral etiology of bronchiolitis. Follow-up data on current asthma or lung function at 6 or 11 years of age after bronchiolitis were not associated with the investigated mutations.

CONCLUSION

Toll-interacting protein gene point mutations in rs116938768 or rs5743854 were not involved with the clinical course of viral bronchiolitis in early infancy, and did not predict post-bronchiolitis asthma or lung function reduction by the age of 11 years.

Alternative Gene Expression by TOLLIP Variant Is Associated With Lung Function in Chronic Hypersensitivity Pneumonitis

BACKGROUND

Chronic hypersensitivity pneumonitis (CHP) is a heterogeneous fibrotic interstitial pneumonia resulting from the immune response of susceptible individuals to inhaled antigens. Genetic predispositions have been suggested in CHP; however, the link between susceptibility genes and fibrotic progression has not been elucidated fully. Recent data suggest that variants in Toll-interacting protein (TOLLIP) are associated with lung diseases.

RESEARCH QUESTION

Can TOLLIP variants be associated with any clinical features in patients with CHP?

STUDY DESIGN AND METHODS

We genotyped rs5743899 and rs3750920 in TOLLIP and analyzed the association with clinical parameters in 101 patients with CHP (67 for the retrospective cohort and 34 for the prospective cohort). We evaluated the expression of TOLLIP and fibrogenic signals in affected lung tissues and periostin in sera. Furthermore, we performed immunologic analysis in the lungs and sera.

RESULTS

The rs5743899 GG genotype was associated with rapid deterioration in FVC over time, which demonstrated significant annual decline in the retrospective cohort (vs AA, P = .0006; vs AG, P < .0001), prospective cohort (vs AA, P < .0001; vs AG, P = .003), and combined cohort (both P < .0001). The patients with the GG genotype demonstrated lower transcription-translation levels of TOLLIP as well as increased phosphorylation of Smad2 and inhibitor of kappa B in the lung tissues and exhibited higher serum levels of periostin, IL-1α, IL-1β, IL-6, IL-8, tumor necrosis factor α, and IFN-γ.

INTERPRETATION

The functional changes by TOLLIP variant were associated with rapid FVC decline through dysregulated Smad/transforming growth factor β and NF-κB signaling in CHP.

Toll-Interacting Protein in Pulmonary Diseases. Abiding by the Goldilocks Principle

TOLLIP (Toll-interacting protein) is an intracellular adaptor protein with diverse actions throughout the body. In a context- and cell type–specific manner, TOLLIP can function as an inhibitor of inflammation and endoplasmic-reticulum stress, an activator of autophagy, or a critical regulator of intracellular vacuole trafficking. The distinct functions of this protein have been linked to innate immune responses and lung epithelial-cell apoptosis. TOLLIP genetic variants have been associated with a variety of chronic lung diseases, including idiopathic pulmonary fibrosis, asthma, and primary graft dysfunction after lung transplantation, and with infections, such as tuberculosis, Legionella pneumonia, and respiratory viruses. TOLLIP exists in a delicate homeostatic balance, with both positive and negative effects on the trajectory of pulmonary diseases. This translational review summarizes the genetic and molecular associations that link TOLLIP to the development and progression of noninfectious and infectious pulmonary diseases. We highlight current limitations of in vitro and in vivo models in assessing the role of TOLLIP in these conditions, and we describe future approaches that will enable a more nuanced exploration of the role of TOLLIP in pulmonary conditions. There has been a surge in recent research evaluating the role of this protein in human diseases, but critical mechanistic pathways require further exploration. By understanding its biologic functions in disease-specific contexts, we will be able to determine whether TOLLIP can be therapeutically modulated to treat pulmonary diseases.

Identification of human immune cell subtypes most responsive to IL-1β-induced inflammatory signaling using mass cytometry

IL-1β is a key mediator of the cytokine storm linked to high morbidity and mortality from COVID-19, and IL-1β blockade with anakinra and canakinumab during COVID-19 infection has entered clinical trials. Using mass cytometry of human peripheral blood mononuclear cells, we identified effector memory CD4⁺ T cells and CD4^-CD8^low/-CD161⁺ T cells, specifically those positive for the chemokine receptor CCR6, as the circulating immune subtypes with the greatest response to IL-1β. This response manifested as increased phosphorylation and, thus, activation of the proinflammatory transcription factor NF-κB and was also seen in other subsets, including CD11c⁺ myeloid dendritic cells, classical monocytes, two subsets of natural killer cells (CD16^-CD56^brightCD161^- and CD16^-CD56^dimCD161⁺), and lineage^- (Lin^-) cells expressing CD161 and CD25. IL-1β also induced a rapid but less robust increase in the phosphorylation of the kinase p38 as compared to that of NF-κB in most of these immune cell subsets. Prolonged IL-1β stimulation increased the phosphorylation of the transcription factor STAT3 and to a lesser extent that of STAT1 and STAT5 across various immune cell types. IL-1β-induced production of IL-6 likely led to the activation of STAT1 and STAT3 at later time points. Interindividual heterogeneity and inhibition of STAT activation by anakinra raise the possibility that assays measuring NF-κB phosphorylation in response to IL-1β in CCR6⁺ T cell subtypes could identify those patients at higher risk of cytokine storm and most likely to benefit from IL-1β-neutralizing therapies.

Potential clinical utility of MUC5B und TOLLIP single nucleotide polymorphisms (SNPs) in the management of patients with IPF

Background

Genetic variants of TOLLIP and MUC5B, both on chromosome 11, have been reported to be associated with the development and/or prognosis of idiopathic pulmonary fibrosis (IPF). This retrospective study was conducted to investigate the association of MUC5B and TOLLIP SNPs with disease outcome in IPF. 62 IPF patients and 50 healthy controls (HC) from our Institution were genotyped for SNPs within MUC5B (rs35705950) and TOLLIP (rs3750920 and rs5743890). Correlation of SNPs genotypes with survival, acute exacerbation (AE) or disease progression (defined as a decline of ≥ 5% in FVC and or ≥ 10% in DLco in one year) was investigated.

Results

The MUC5B rs35705950 minor allele (T) was more frequent in IPF subjects than in HC (35% vs 9% p < 0.001). TOLLIP SNPs alleles and genotype distribution did not differ between IPF and HC and did not vary according to gender, age, BMI and lung functional impairment at baseline. The minor allele (C) in TOLLIP rs5743890 was associated with worse survival and with disease progression in all performed analyses. The MUC5B rs35705950 or the TOLLIP rs3750920 minor allele, were not associated with disease progression or AE.

Conclusion

We confirm that the minor allele of MUC5B rs35705950 is associated with IPF. The minor allele of TOLLIP rs5743890 appears to be a predictor of worse survival and more rapid disease progression, therefore being of potential utility to stratify IPF patients at baseline.

Toll-interacting protein impacts on inflammation, autophagy, and vacuole trafficking in human disease

Toll-interacting protein (TOLLIP) is a ubiquitous intracellular adaptor protein involved in multiple intracellular signaling pathways. It plays a key role in mediating inflammatory intracellular responses, promoting autophagy, and enabling vacuole transport within the cell. TOLLIP is being increasingly recognized for its role in disease pathophysiology through involvement in these three primary pathways. Recent research also indicates that TOLLIP is involved in nuclear-cytoplasmic transfer, although this area requires further exploration. TOLLIP is involved in the pathophysiologic pathways associated with neurodegenerative diseases, pulmonary diseases, cardiovascular disease, inflammatory bowel disease, and malignancy. We postulate that TOLLIP plays an integral role in the disease pathophysiology of other conditions involved in vacuole trafficking and autophagy. We suggest that future research in this field should investigate the role of TOLLIP in the pathogenesis of these multiple conditions. This research has the potential to inform disease mechanisms and identify novel opportunities for therapeutic advances in multiple disease processes.

Interleukin 1 Receptor-Like 1 (IL1RL1) Promotes Airway Bacterial and Viral Infection and Inflammation

Interleukin 1 receptor-like 1 (IL1RL1), also known as suppression of tumorigenicity 2 (ST2), is the receptor for interleukin 33 (IL-33) and has been increasingly studied in type 2 inflammation. An increase in airway IL-33/ST2 signaling in asthma has been associated with eosinophilic inflammation, but little is known about the role of ST2 in neutrophilic inflammation. Airway Mycoplasma pneumoniae and human rhinovirus (HRV) infections are linked to neutrophilic inflammation during acute exacerbations of asthma. However, whether ST2 contributes to M. pneumoniae- and HRV-mediated airway inflammation is poorly understood. The current study sought to determine the functions of ST2 during airway M. pneumoniae or HRV infection. In cultured normal human primary airway epithelial cells, ST2 overexpression (OE) increased the production of neutrophilic chemoattractant IL-8 in the absence or presence of M. pneumoniae or HRV1B infection. ST2 OE also enhanced HRV1B-induced IP-10, a chemokine involved in asthma exacerbations. In the M. pneumoniae-infected mouse model, ST2 deficiency, in contrast to sufficiency, significantly reduced the levels of neutrophils following acute (≤24 h) infection, while in the HRV1B-infected mouse model, ST2 deficiency significantly reduced the levels of proinflammatory cytokines KC, IP-10, and IL-33 in bronchoalveolar lavage (BAL) fluid. Overall, ST2 overexpression in human epithelial cells and ST2 sufficiency in mice increased the M. pneumoniae and HRV loads in cell supernatants and BAL fluid. After pathogen infection, ST2-deficient mice showed a higher level of the host defense protein lactotransferrin in BAL fluid. Our data suggest that ST2 promotes proinflammatory responses (e.g., neutrophils) to airway bacterial and viral infection and that blocking ST2 signaling may broadly attenuate airway infection and inflammation.

Tollip Inhibits ST2 Signaling in Airway Epithelial Cells Exposed to Type 2 Cytokines and Rhinovirus

The negative immune regulator Tollip inhibits the proinflammatory response to rhinovirus (RV) infection, a contributor to airway neutrophilic inflammation and asthma exacerbations, but the underlying molecular mechanisms are poorly understood. Tollip may inhibit IRAK1, a signaling molecule downstream of ST2, the receptor of IL-33. This study was carried out to determine whether Tollip downregulates ST2 signaling via inhibition of IRAK1, but promotes soluble ST2 (sST2) production, thereby limiting excessive IL-8 production in human airway epithelial cells during RV infection in a type 2 cytokine milieu (e.g., IL-13 and IL-33 stimulation). Tollip- and IRAK1-deficient primary human tracheobronchial epithelial (HTBE) cells and Tollip knockout (KO) HTBE cells were generated using the shRNA knockdown and CRISPR/Cas9 approaches, respectively. Cells were stimulated with IL-13, IL-33, and/or RV16. sST2, activated IRAK1, and IL-8 were measured. A Tollip KO mouse model was utilized to test if Tollip regulates the airway inflammatory response to RV infection in vivo under IL-13 and IL-33 treatment. Following IL-13, IL-33, and RV treatment, Tollip-deficient (vs. -sufficient) HTBE cells produced excessive IL-8, accompanied by decreased sST2 production but increased IRAK1 activation. IL-8 production following IL-13/IL-33/RV exposure was markedly attenuated in IRAK1-deficient HTBE cells, as well as in Tollip KO HTBE cells treated with an IRAK1 inhibitor or a recombinant sST2 protein. Tollip KO (vs. wild-type) mice developed exaggerated airway neutrophilic responses to RV in the context of IL-13 and IL-33 treatment. Collectively, these data demonstrate that Tollip restricts excessive IL-8 production in type 2 cytokine-exposed human airways during RV infection by promoting sST2 production and inhibiting IRAK1 activation. sST2 and IRAK1 may be therapeutic targets for attenuating excessive neutrophilic airway inflammation in asthma, especially during RV infection.

Toll-interacting protein differentially modulates HIF1α and STAT5-mediated genes in fibroblasts

Toll-interacting protein (Tollip) deficiency has been implicated in complex inflammatory and infectious diseases whose mechanisms are poorly understood. Comparing the gene expression profiles of WT and Tollip-deficient murine embryonic fibroblasts, we observed here that Tollip deficiency selectively reduces the expression of the inflammatory cytokines interleukin 6 (IL-6), IL-12, and tumor necrosis factor α (TNFα) but potentiates the expression of fatty acid-binding protein 4 (FABP4) in these cells. We also observed that expression of hypoxia-inducible factor 1-α (HIF1α) is reduced, whereas that of signal transducer and activator of transcription 5 (STAT5) is elevated, in Tollip-deficient cells, correlating with the decreased expression of inflammatory cytokines and increased expression of FABP4 in these cells. We further found that the coupling of ubiquitin to ER degradation (CUE) domain of Tollip is required for stimulating HIF1α activity, because Tollip CUE-domain mutant cells exhibited reduced levels of HIF1α and selected cytokines. Tollip is known to mediate autophagy and lysosome fusion, and herein we observed that Tollip's autophagy function is required for modulating STAT5 and FABP4 expression. Bafilomycin A, an inhibitor of lysosome fusion, enhanced STAT5 and FABP4 expression in WT fibroblasts, whereas torin 2, an activator of autophagy, reduced STAT5 and FABP4 expression in Tollip-deficient fibroblasts. Taken together, our study reveals that Tollip differentially modulates HIF1α and STAT5 expression in fibroblasts, potentially explaining the complex and context-dependent contribution of Tollip to disease development.

Comparison of paired human nasal and bronchial airway epithelial cell responses to rhinovirus infection and IL-13 treatment

BACKGROUND

Because of its advantage as a minimally invasive procedure, nasal brushings have been increasingly used and proposed as a valuable approach to study lower airway diseases in lieu of bronchial epithelial cells. However, there is limited or conflicting evidence pertaining to whether nasal samples can be surrogates to bronchial samples. The goal of the present study is to test whether nasal epithelial cells have similar antiviral and inflammatory responses to IL-13 treatment and rhinovirus infection, a condition mimicking virally induced asthma exacerbation. Nasal and bronchial airway epithelial cells taken from the same patient were cultured under submerged and air-liquid interface (ALI) culture in the absence or presence of rhinovirus and IL-13 treatment. Inflammatory cytokines IP-10 and eotaxin-3, antiviral gene Mx1 and viral levels were measured.

RESULTS

In the absence of IL-13 treatment, nasal and bronchial cells showed a similar IP-10 response in both ALI and submerged cultures. Under the ALI culture, short term (e.g., 3 days) IL-13 treatment had a minimal effect on viral and Mx1 levels in both cell types. However, prolonged (e.g., 14 days) IL-13 treatments in both cell types decreased viral load and Mx1 expression. Under the submerged culture, IL-13 treatment in both cell types has minimal effects on viral load, IP-10 and Mx1. IL-13-induced eotaxin-3 production was similar in both types of cells under either submerged or ALI culture, which was not affected by viral infection.

CONCLUSIONS

Our data suggest that nasal epithelial cells could serve as a surrogate to bronchial epithelial cells in future studies aimed at defining the role of type 2 cytokine IL-13 in regulating pro-inflammatory and antiviral responses.

Understanding Root Causes of Asthma. Perinatal Environmental Exposures and Epigenetic Regulation

A common explanation for the origins and rising prevalence of asthma is that they involve complex interactions between hereditary predispositions and environmental exposures that are incompletely understood. Yet, emerging evidence substantiates the paradigm that environmental exposures prenatally and during very early childhood induce epigenetic alterations that affect the expression of asthma genes and, thereby, asthma itself. Here, we review much of the key evidence supporting this paradigm. First, we describe evidence that the prenatal and early postnatal periods are key time windows of susceptibility to environmental exposures that may trigger asthma. Second, we explain how environmental epigenetic regulation may explain the immunopathology underlying asthma. Third, we outline specific evidence that environmental exposures induce epigenetic regulation, both from animal models and robust human epidemiological research. Finally, we review some emerging topics, including the importance of coexposures, population divergence, and how epigenetic regulation may change over time. Despite all the inherent complexity, great progress has been made toward understanding what we still consider reversible asthma risk factors. These, in time, may impact patient care.

Toll-Interacting Protein, Tollip, Inhibits IL-13-Mediated Pulmonary Eosinophilic Inflammation in Mice

Toll-interacting protein (Tollip) is a key negative regulator of innate immunity by preventing excessive proinflammatory responses. Tollip genetic variation has been associated with airflow limitation in asthma subjects and Tollip expression. Whether Tollip regulates lung inflammation in a type 2 cytokine milieu (e.g., IL-13) is unclear. Our goal was to determine the in vivo role of Tollip in IL-13-mediated lung eosinophilic inflammation and the underlying mechanisms. Tollip-knockout (KO) and wild-type (WT) mice were inoculated intranasally with recombinant mouse IL-13 protein to examine lung inflammation. To determine how Tollip regulates inflammation, alveolar macrophages and bone marrow-derived macrophages from Tollip KO and WT mice were cultured with or without IL-13 and/or IL-33. IL-13-treated Tollip KO mice significantly increased lung eosinophilic inflammation and eotaxin-2 (CCL24) levels compared with the WT mice. IL-13- treated Tollip KO (vs. WT) macrophages, in the absence and particularly in the presence of IL-33, increased expression of the IL-33 receptor ST2L and CCL24, which was in part dependent on enhanced activation of interleukin (IL)-1 receptor-associated kinase 1 (IRAK1) and signal transducer and activator of transcription 6 (STAT6). Our results suggest that Tollip downregulates IL-13-mediated pulmonary eosinophilia in part through inhibiting the activity of the ST2L/IL-33/IRAK1 axis and STAT6.