Inflammatory responses to acute pneumovirus infection in neonatal mice

Background: The innate immune responses of neonates differ dramatically from those of adults. Here we examine the acute inflammatory responses of neonatal and weanling mice infected with pneumonia virus of mice (PVM), a rodent pathogen (family Paramyxoviridae, genus Pneumovirus) that replicates the sequelae of severe respiratory syncytial virus infection. Results: We demonstrate that virus replication proceeds indistinguishably in all age groups (inoculated at 1, 2, 3 and 4 weeks of age), although inflammatory responses vary in extent and character. Some of the biochemical mediators detected varied minimally with age at inoculation. Most of the mediators evaluated demonstrated elevated expression over baseline correlating directly with age at the time of virus inoculation. Among the latter group are CCL2, CCL3, and IFN-γ, all cytokines previously associated with PVM-induced inflammatory pathology in mature mice. Likewise, we detect neutrophil recruitment to lung tissue in all age groups, but recruitment is most pronounced among the older (3 - 4 week old) mice. Interestingly, all mice exhibit failure to thrive, lagging in expected weight gain for given age, including the youngest mice that present little overt evidence of inflammation. Conclusions: Our findings among the youngest mice may explain in part the phenomenon of atypical or minimally symptomatic respiratory infections in human neonates, which may be explored further with this infection model

Inhibition of uric acid or IL- 1β ameliorates respiratory syncytial virus immunopathology and development of asthma

BackgroundRespiratory syncytial virus (RSV) affects most infants early in life and is associated with increased asthma risk. The specific mechanism remains unknown.ObjectiveTo investigate the role of uric acid (UA) and IL- 1β in RSV immunopathology and asthma predisposition.MethodsTracheal aspirates from human infants with and without RSV were collected and analyzed for pro- IL- 1β mRNA and protein to establish a correlation in human disease. Neonatal mouse models of RSV were employed, wherein mice infected at 6- 7 days of life were analyzed at 8 days postinfection, 5 weeks postinfection, or after a chronic cockroach allergen asthma model. A xanthine oxidase inhibitor or IL- 1 receptor antagonist was administered during RSV infection.ResultsHuman tracheal aspirates from RSV- infected infants showed elevated pro- IL- 1β mRNA and protein. Inhibition of UA or IL- 1β during neonatal murine RSV infection decreased mucus production, reduced cellular infiltrates to the lung (especially ILC2s), and decreased type 2 immune responses. Inhibition of either UA or IL- 1β during RSV infection led to chronic reductions in pulmonary immune cell composition and reduced type 2 immune responses and reduced similar responses after challenge with cockroach antigen.ConclusionsInhibiting UA and IL- 1β during RSV infection ameliorates RSV immunopathology, reduces the consequences of allergen- induced asthma, and presents new therapeutic targets to reduce early- life viral- induced asthma development.Neonatal RSV infection is associated with increases in pulmonary uric acid and IL- 1β and lung immunopathology. XOI or IL- 1RA administration during neonatal RSV infection leads to reduced RSV immunopathology. XOI or IL- 1RA administration during neonatal RSV infection leads to reduced type 2 immune responses during a subsequent model of asthma.Abbreviations: IL- 1RA, IL- 1 receptor antagonist; RSV: Respiratory syncytial virus; XOI, xanthine oxidase inhibitor.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/162774/3/all14310.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/162774/2/all14310_am.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/162774/1/all14310-sup-0005-TableS1.pd

Epigenetic regulation of IL‐12‐dependent T cell proliferation

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/141412/1/jlb0601-sup-0001.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/141412/2/jlb0601.pd

Factors Affecting the Immunity to Respiratory Syncytial Virus: From Epigenetics to Microbiome

Respiratory syncytial virus (RSV) is a common pathogen that infects virtually all children by 2 years of age and is the leading cause of hospitalization of infants worldwide. While most children experience mild symptoms, some children progress to severe lower respiratory tract infection. Those children with severe disease have a much higher risk of developing childhood wheezing later in life. Many risk factors are known to result in exacerbated disease, including premature birth and early age of RSV infection, when the immune system is relatively immature. The development of the immune system before and after birth may be altered by several extrinsic and intrinsic factors that could lead to severe disease predisposition in children who do not exhibit any currently known risk factors. Recently, the role of the microbiome and the resulting metabolite profile has been an area of intense study in the development of lung disease, including viral infection and asthma. This review explores both known risk factors that can lead to severe RSV-induced disease as well as emerging topics in the development of immunity to RSV and the long-term consequences of severe infection

RSV-Induced H3K4 Demethylase KDM5B Leads to Regulation of Dendritic Cell-Derived Innate Cytokines and Exacerbates Pathogenesis In Vivo

Respiratory syncytial virus (RSV) infection can result in severe disease partially due to its ability to interfere with the initiation of Th1 responses targeting the production of type I interferons (IFN) and promoting a Th2 immune environment. Epigenetic modulation of gene transcription has been shown to be important in regulating inflammatory pathways. RSV-infected bone marrow-derived DCs (BMDCs) upregulated expression of Kdm5b/Jarid1b H3K4 demethylase. Kdm5b-specific siRNA inhibition in BMDC led to a 10-fold increase in IFN-β as well as increases in IL-6 and TNF-α compared to control-transfected cells. The generation of Kdm5bfl/fl-CD11c-Cre+ mice recapitulated the latter results during in vitro DC activation showing innate cytokine modulation. In vivo, infection of Kdm5bfl/fl-CD11c-Cre+ mice with RSV resulted in higher production of IFN-γ and reduced IL-4 and IL-5 compared to littermate controls, with significantly decreased inflammation, IL-13, and mucus production in the lungs. Sensitization with RSV-infected DCs into the airways of naïve mice led to an exacerbated response when mice were challenged with live RSV infection. When Kdm5b was blocked in DCs with siRNA or DCs from Kdm5bfl/fl-CD11c-CRE mice were used, the exacerbated response was abrogated. Importantly, human monocyte-derived DCs treated with a chemical inhibitor for KDM5B resulted in increased innate cytokine levels as well as elicited decreased Th2 cytokines when co-cultured with RSV reactivated CD4+ T cells. These results suggest that KDM5B acts to repress type I IFN and other innate cytokines to promote an altered immune response following RSV infection that contributes to development of chronic disease

Inhibition of uric acid or IL‐1β ameliorates respiratory syncytial virus immunopathology and development of asthma

BackgroundRespiratory syncytial virus (RSV) affects most infants early in life and is associated with increased asthma risk. The specific mechanism remains unknown.ObjectiveTo investigate the role of uric acid (UA) and IL- 1β in RSV immunopathology and asthma predisposition.MethodsTracheal aspirates from human infants with and without RSV were collected and analyzed for pro- IL- 1β mRNA and protein to establish a correlation in human disease. Neonatal mouse models of RSV were employed, wherein mice infected at 6- 7 days of life were analyzed at 8 days postinfection, 5 weeks postinfection, or after a chronic cockroach allergen asthma model. A xanthine oxidase inhibitor or IL- 1 receptor antagonist was administered during RSV infection.ResultsHuman tracheal aspirates from RSV- infected infants showed elevated pro- IL- 1β mRNA and protein. Inhibition of UA or IL- 1β during neonatal murine RSV infection decreased mucus production, reduced cellular infiltrates to the lung (especially ILC2s), and decreased type 2 immune responses. Inhibition of either UA or IL- 1β during RSV infection led to chronic reductions in pulmonary immune cell composition and reduced type 2 immune responses and reduced similar responses after challenge with cockroach antigen.ConclusionsInhibiting UA and IL- 1β during RSV infection ameliorates RSV immunopathology, reduces the consequences of allergen- induced asthma, and presents new therapeutic targets to reduce early- life viral- induced asthma development.Neonatal RSV infection is associated with increases in pulmonary uric acid and IL- 1β and lung immunopathology. XOI or IL- 1RA administration during neonatal RSV infection leads to reduced RSV immunopathology. XOI or IL- 1RA administration during neonatal RSV infection leads to reduced type 2 immune responses during a subsequent model of asthma.Abbreviations: IL- 1RA, IL- 1 receptor antagonist; RSV: Respiratory syncytial virus; XOI, xanthine oxidase inhibitor.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/162774/3/all14310.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/162774/2/all14310_am.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/162774/1/all14310-sup-0005-TableS1.pd

In Vivo Activation of Toll-Like Receptor-9 Induces an Age-Dependent Abortive Lytic Cycle Reactivation of Murine Gammaherpesvirus-68

Infection of mice with murine gammaherpesvirus-68 (γHV-68) serves as a model to understand the pathogenesis of persistent viral infections, including the potential for co-infections to modulate viral latency. We have previously found that infection of neonates (8-day-old mice) with γHV-68 resulted in a high level of persistence of the virus in the lungs as well as the spleen, in contrast to infection of adult mice, for which long-term latency was only readily detected in the spleen. In this study we investigated whether stimulation of toll-like receptor (TLR)9 would modulate viral latency in mice infected with γHV-68 in an age-dependent manner. Pups and adult mice were injected with the synthetic TLR9 ligand CpG ODN at 30 dpi, at which time long-term latency has been established. Three days after CpG injection, the lungs and spleens were removed, and a limiting dilution assay was done to determine the frequency of latently infected cells. RNA was extracted to measure viral transcripts using a ribonuclease protection assay. We observed that CpG injection resulted in an increase in the frequency of latently-infected cells in both the lungs and spleens of infected pups, but only in the spleens of infected adult mice. No preformed virus was detected, suggesting that TLR9 stimulation did not trigger complete viral reactivation. When we examined viral gene expression in these same tissues, we observed expression only of the immediate early lytic genes, rta and K3, but not the early DNA polymerase gene or late gB transcript indicative of an abortive reactivation in the spleen. Additionally, mice infected as pups had greater numbers of germinal center B cells in the spleen following CpG injection, whereas CpG stimulated the expansion of follicular zone B cells in adult mice. These data suggest that stimulation of TLR9 differentially modulates gammaherpesvirus latency via an age-dependent mechanism

Sensitizing the lungs with <i>Kdm5b</i>^f/f-CD11c-Cre⁺ DCs prior to infection results in decreased pathology following RSV challenge.

<p>BMDCs from <i>Kdm5b</i>^f/f-CD11c-Cre⁺ mice or Cre^- controls were infected with RSV for 24 hours <i>in vitro</i>, then washed and administered intratracheally to WT C57BL/6 mice. After 7 days, mice were then infected with RSV, and samples were measured at 8 dpi. Mice infected with RSV alone were included as a control. (A) Lungs were removed and sections stained with H&E to visualize inflammation. (B) MLN were removed and restimulated <i>in vitro</i> for 48 hours with RSV. Supernatant proteins were measured by bioplex assay. (C) Lungs were homogenized into a single cell suspension and the number of CD11c⁺CD11b⁺ and CD11c⁺CD103⁺ DCs was quantified by flow cytometry. (D) CD4⁺ T cells and activated CD4⁺CD69⁺ T cells were measured by flow cytometry. (E) Lung sections were stained with PAS to visualize mucus production. Arrows indicate mucus production. (F) RNA was extracted from homogenized lung tissue and <i>Muc5ac</i> and <i>Gob5</i> were measured by qPCR. *p<0.05, **p<0.01.</p