Attenuated Airway Epithelial Cell Interleukin-22R1 Expression in the Infant Nonhuman Primate Lung

Dectin-1 genetic deficiency predicts chronic lung allograft dysfunction and death

BACKGROUNDInnate immune activation impacts lung transplant outcomes. Dectin-1 is an innate receptor important for pathogen recognition. We hypothesized that genotypes reducing dectin-1 activity would be associated with infection, graft dysfunction, and death in lung transplant recipients.METHODSWe assessed the rs16910526 CLEC7A gene polymorphism Y238X, which results in dectin-1 truncation, in 321 lung allograft recipients at a single institution and in 1,129 lung allograft recipients in the multicenter Lung Transplant Outcomes Group (LTOG) cohort. Differences in dectin-1 mRNA, cytokines, protein levels, immunophenotypes, and clinical factors were assessed.RESULTSY238X carriers had decreased dectin-1 mRNA expression (P = 0.0001), decreased soluble dectin-1 protein concentrations in bronchoalveolar lavage (P = 0.008) and plasma (P = 0.04), and decreased monocyte surface dectin-1 (P = 0.01) compared with wild-type subjects. Y238X carriers had an increased risk of fungal pathogens (HR 1.17, CI 1.0-1.4), an increased risk of graft dysfunction or death (HR 1.6, CI 1.0-2.6), as well increased mortality in the UCSF cohort (HR 1.8, CI 1.1-3.8) and in the LTOG cohort (HR 1.3, CI 1.1-1.6), compared with wild-type CLEC7A subjects.CONCLUSIONIncreased rates of graft dysfunction and death associated with this dectin-1 polymorphism may be amplified by immunosuppression that drives higher fungal burden from compromised pathogen recognition.FUNDINGThe UCSF Nina Ireland Program for Lung Health Innovative Grant program, the Clinical Sciences Research & Development Service of the VA Office of Research and Development, and the Joel D. Cooper Career Development Award from the International Society for Heart and Lung Transplantation.

IL-22Ra1 is induced during influenza infection by direct and indirect TLR3 induction of STAT1

BACKGROUND

Influenza attacks the epithelium of the lung, causing cell death and disruption of the epithelial barrier leading to fluid buildup in the lung and impairment of gas exchange. Limited treatment options for severe influenza pneumonia prioritize the need for the discovery of effective therapies. IL-22 is a cytokine that promotes tissue integrity and has strong promise as a treatment option. While research has been focused on the cytokine itself, there is limited understanding of the regulation of the IL-22 receptor (IL-22Ra1) at the epithelial surface during infection.

METHODS

IL-22Ra1 levels were measured by qRT-PCR, western blot and immunofluorescence following H1N1 influenza infection (A/PR/8/34 H1N1) or synthetic TLR3 mimetic, Poly (I:C). Regulation of the receptor was determined using STAT inhibitors (STAT1, STAT3 and PanSTAT inhibitors), TLR3 inhibition, and neutralization of interferon alpha receptor 2 (IFNAR2). Significance was determined by a p-value of greater than 0.05. Significance between two groups was measured using unpaired t-test and significance between more than two groups was measured using one-way ANOVA with Tukey Multiple Comparison Test.

RESULTS

Here we show both in vivo and in vitro that IL-22Ra1 was induced as early as 24 h after influenza (H1N1 PR8) infection. This induction was triggered by toll-like receptor 3 (TLR3) as a TLR3 mimetic [Poly (I:C)] also induced IL-22Ra1 and inhibition of endosomal formation required for TLR3 function inhibited this process. This upregulation was dependent upon IFNβ signaling through STAT1. Importantly, induction of IL-22Ra1 significantly increased IL-22 signaling as evidenced by pSTAT3 levels following IL-22 treatment.

CONCLUSION

Collectively, these data suggest epithelial cells may optimize the beneficial effects of IL-22 through the induction of the IL-22 receptor during viral infection in the lung.

Recent advances in our understanding of the mechanisms of late lung development and bronchopulmonary dysplasia

The objective of lung development is to generate an organ of gas exchange that provides both a thin gas diffusion barrier and a large gas diffusion surface area, which concomitantly generates a steep gas diffusion concentration gradient. As such, the lung is perfectly structured to undertake the function of gas exchange: a large number of small alveoli provide extensive surface area within the limited volume of the lung, and a delicate alveolo-capillary barrier brings circulating blood into close proximity to the inspired air. Efficient movement of inspired air and circulating blood through the conducting airways and conducting vessels, respectively, generates steep oxygen and carbon dioxide concentration gradients across the alveolo-capillary barrier, providing ideal conditions for effective diffusion of both gases during breathing. The development of the gas exchange apparatus of the lung occurs during the second phase of lung development-namely, late lung development-which includes the canalicular, saccular, and alveolar stages of lung development. It is during these stages of lung development that preterm-born infants are delivered, when the lung is not yet competent for effective gas exchange. These infants may develop bronchopulmonary dysplasia (BPD), a syndrome complicated by disturbances to the development of the alveoli and the pulmonary vasculature. It is the objective of this review to update the reader about recent developments that further our understanding of the mechanisms of lung alveolarization and vascularization and the pathogenesis of BPD and other neonatal lung diseases that feature lung hypoplasia.

The Helicobacter pylori type IV secretion system promotes IL-8 synthesis in a model of pediatric airway epithelium via p38 MAP kinase

Epidemiologic studies have reported an inverse relationship between childhood Helicobacter pylori infection and development of allergic asthma. Because lung epithelium plays an important role in allergic asthma pathogenesis, we hypothesized that H. pylori may directly influence airway epithelial cell innate immune function, particularly in early childhood. To test our hypothesis, we established an in vitro H. pylori infection model using primary tracheobronchial epithelial cell cultures derived from infant, juvenile and adult rhesus monkeys. Airway epithelial cell cultures were infected with wild-type or cag pathogenicity island mutant H. pylori strains, followed by evaluation of IL-8 and IL-6 protein synthesis. We found that H. pylori primarily increased IL-8 synthesis in a MOI and age-dependent fashion, with a greater than 4-fold induction in infant versus adult cultures. H. pylori-induced IL-8 synthesis in infant and juvenile cultures was significantly reduced by cag pathogenicity island mutants, indicating a requirement for the type IV secretion system. Although peptidoglycan recognition of nucleotide binding oligomerization domain-containing protein 1 (NOD1) and NF-kappaB have been implicated as key cytokine signaling molecules for H. pylori infection in gastric epithelium, NOD1 (ML130) or NF-kappaB (JSH-23) inhibitors minimally affected IL-8 synthesis in airway epithelial cell cultures following H. pylori infection. In contrast, inhibition of the p38 MAP kinase pathway (SB203580) resulted in almost complete suppression of H. pylori-induced IL-8 synthesis. Collectively, these results indicate that H. pylori can preferentially elicit IL-8 synthesis in a model of pediatric airway epithelium using the type IV secretion system via p38 MAP kinase.

Hyperphosphorylation of RPS6KB1, rather than overexpression, predicts worse prognosis in non-small cell lung cancer patients

RPS6KB1 is the kinase of ribosomal protein S6 which is 70 kDa and is required for protein translation. Although the abnormal activation of RPS6KB1 has been found in types of diseases, its role and clinical significance in non-small cell lung cancer (NSCLC) has not been fully investigated. In this study, we identified that RPS6KB1 was over-phosphorylated (p-RPS6KB1) in NSCLC and it was an independent unfavorable prognostic marker for NSCLC patients. In spite of the frequent expression of total RPS6KB1 and p-RPS6KB1 in NSCLC specimens by immunohistochemical staining (IHC), only p-RPS6KB1 was associated with the clinicopathologic characteristics of NSCLC subjects. Kaplan-Meier survival analysis revealed that the increased expression of p-RPS6KB1 indicated a poorer 5-year overall survival (OS) for NSCLC patients, while the difference between the positive or negative RPS6KB1 group was not significant. Univariate and multivariate Cox regression analysis was then used to confirm the independent prognostic value of p-RPS6KB1. To illustrate the underlying mechanism of RPS6KB1 phosphorylation in NSCLC, LY2584702 was employed to inhibit the RPS6KB1 phosphorylation specifically both in lung adenocarcinoma cell line A549 and squamous cell carcinoma cell line SK-MES-1. As expected, RPS6KB1 dephosphorylation remarkably suppressed cells proliferation in CCK-8 test, and promoted more cells arresting in G0-G1 phase by cell cycle analysis. Moreover, apoptotic A549 cells with RPS6KB1 dephosphorylation increased dramatically, with an elevating trend in SK-MES-1, indicating a potential involvement of RPS6KB1 phosphorylation in inducing apoptosis. In conclusion, our data suggest that RPS6KB1 is over-activated as p-RPS6KB1 in NSCLC, rather than just the total protein overexpressing. The phosphorylation level of RPS6KB1 might be used as a novel prognostic marker for NSCLC patients.