Type I interferons (IFNs) are important enhancers of immune responses which are downregulated in human cancers, including skin cancer. Solar ultraviolet (UV) B radiation is a proven environmental carcinogen, and its exposure contributes to the high prevalence of skin cancer. The carcinogenic effects of UV light can be attributed to the formation of cyclobutane pyrimidine dimers (CPD) and errors in the repair and replication of DNA. Treatment with a single dose of UVB (100 mJ/cm2) upregulated IFNα and IFNβ in the skin of C57BL/6 mice. IFNα and IFNβ were predominantly produced by CD11b+ cells. In mice lacking the type I IFN receptor 1 (IFNAR1), the repair of CPD following cutaneous exposure to a single dose of UVB (100 mJ/cm2) was decreased. UVB induced the expression of the DNA repair gene xeroderma pigmentosum A (XPA) in wild-type (WT) mice. In contrast, such treatment in IFNAR1 (IFNAR1-/-) mice downregulated XPA. A local UVB regimen consisting of UVB radiation (150 mJ/cm2) for 4 days followed by sensitization with hapten 2,4, dinitrofluorobenzene (DNFB) resulted in significant suppression of immune responses in both WT and IFNAR1-/- mice. However, there were significantly higher CD4+CD25+Foxp3+ regulatory T-cells in the draining lymph nodes of IFNAR1-/- mice in comparison to WT mice. Overall, our studies reveal a previously unknown action of type I IFNs in the repair of photodamage and the prevention of UVB-induced immune suppression.
This repository contains the OTU tables for "Antimicrobial peptides modulate pulmonary inflammation by altering the intestinal microbiota" by Abdelgawad and Nicola et al., an analysis of the role of antimicrobial peptide in the gut-lung axis during hyperoxia-induced lung injury. This work was supported by the National Heart, Lung, and Blood Institute of the U.S. National Institutes of Health, K NIH: K08 HL151907 (KW), K08 HL141652 (CL), K08 DK120871 (AO); the Kaul Pediatric Research Institute at Children’s of Alabama (KW), and the Microbiome Center at UAB (KW). The funding agencies had no role in the design, conduct, and analysis of the study or in the decision to submit the manuscript for publication. The content is solely the responsibility of the authors and does not necessarily represent the official views of the NIH. All data in this repository is the intellectual property of the authors and may be utilized for academic publication only with prior written permission.
The immature lungs of very preterm infants are exposed to supraphysiologic oxygen, contributing to bronchopulmonary dysplasia (BPD), a chronic lung disease that is the most common morbidity of prematurity. While the microbiota significantly influences neonatal health, the relationship between the intestinal microbiome, particularly micro-eukaryotic members such as fungi and yeast, and lung injury severity in newborns remains unknown. Here, we show that the fungal microbiota modulates hyperoxia-induced lung injury severity in very low birth weight premature infants and preclinical pseudohumanized and altered fungal colonization mouse models. Instead of fungal communities dominated by Candida and Saccharomyces, the first stool microbiomes of infants who developed BPD had less interconnected community architectures with a greater diversity of rarer fungi. After using a pseudohumanized model to show that transfer to the neonatal microbiome from infants with BPD increased the severity of lung injury, we used gain and loss of function approaches to demonstrate that modulating the extent of initial neonatal fungal colonization affected the extent of BPD-like lung injury in mice. We also identified alterations in the murine intestinal microbiome and transcriptome associated with augmented lung injury. These findings demonstrate that features of the initial intestinal fungal microbiome are associated with the later development of BPD in premature neonates and exert a microbiome-driven effect that is transferable and modifiable in murine models, which suggests both causality and a potential therapeutic strategy.
Bronchopulmonary dysplasia (BPD) is a common lung disease of premature infants. Hyperoxia exposure and microbial dysbiosis are contributors to BPD development. However, the mechanisms linking pulmonary microbial dysbiosis to worsening lung injury are unknown. Nrf2 (nuclear factor erythroid 2-related factor 2) is a transcription factor that regulates oxidative stress responses and modulates hyperoxia-induced lung injury. We hypothesized that airway dysbiosis would attenuate Nrf2-dependent antioxidant function, resulting in a more severe phenotype of BPD. Here, we show that preterm infants with a Gammaproteobacteria-predominant dysbiosis have increased endotoxin in tracheal aspirates, and mice monocolonized with the representative Gammaproteobacteria Escherichia coli show increased tissue damage compared with germ-free (GF) control mice. Furthermore, we show Nrf2-deficient mice have worse lung structure and function after exposure to hyperoxia when the airway microbiome is augmented with E. coli. To confirm the disease-initiating potential of airway dysbiosis, we developed a novel humanized mouse model by colonizing GF mice with tracheal aspirates from human infants with or without severe BPD, producing gnotobiotic mice with BPD-associated and non-BPD-associated lung microbiomes. After hyperoxia exposure, BPD-associated mice demonstrated a more severe BPD phenotype and increased expression of Nrf2-regulated genes, compared with GF and non-BPD-associated mice. Furthermore, augmenting Nrf2-mediated antioxidant activity by supporting colonization with Lactobacillus species improved dysbiotic-augmented lung injury. Our results demonstrate that a lack of protective pulmonary microbiome signature attenuates an Nrf2-mediated antioxidant response, which is augmented by a respiratory probiotic blend. We anticipate antioxidant pathways will be major targets of future microbiome-based therapeutics for respiratory disease.
Mammalian mucosal barriers secrete antimicrobial peptides (AMPs) as critical host-derived regulators of the microbiota. However, mechanisms that support homeostasis of the microbiota in response to inflammatory stimuli such as supraphysiologic oxygen remain unclear. Here, we show that neonatal mice breathing supraphysiologic oxygen or direct exposure of intestinal organoids to supraphysiologic oxygen suppress the intestinal expression of AMPs and alters the composition of the intestinal microbiota. Oral supplementation of the prototypical AMP lysozyme to hyperoxia exposed neonatal mice reduced hyperoxia-induced alterations in their microbiota and was associated with decreased lung injury. Our results identify a gut-lung axis driven by intestinal AMP expression and mediated by the intestinal microbiota that is linked to lung injury. Together, these data support that intestinal AMPs modulate lung injury and repair.Using a combination of murine models and organoids, Abdelgawad and Nicola et al. find that suppression of antimicrobial peptide release by the neonatal intestine in response to supra-physiological oxygen influences the progression of lung injury likely via modulation of the ileal microbiota.Supraphysiologic oxygen exposure alters intestinal antimicrobial peptides (AMPs).Intestinal AMP expression has an inverse relationship with the severity of lung injury.AMP-driven alterations in the intestinal microbiota form a gut-lung axis that modulates lung injury.AMPs may mediate a gut-lung axis that modulates lung injury.
