Aspergillus fumigatus is an environmental fungus that can cause invasive pulmonary aspergillosis when spores are inhaled into the respiratory tract and invade airway or lung tissue. Influenza is a common respiratory virus that can cause severe respiratory disease, and postinfluenza invasive pulmonary aspergillosis, which is becoming a well-recognized clinical problem, typically occurs in critically ill patients. Mice challenged with influenza A PR/8/34 H1N1 and subsequently challenged with A. fumigatus had increased fungal burden, viral burden, inflammation, and mortality compared with single infected mice. Neutrophil recruitment in the lung of superinfected mice was decreased; however, mice were not neutropenic, and there was no difference in absolute blood neutrophils between groups. Additionally, CXCL1 and CXCL2 were decreased in lungs of superinfected mice compared with controls. IFN levels were increased in mice that received influenza, and deletion of STAT1 resulted in decreased fungal burden, increased airway and lung neutrophils, and increased CXCL1 compared with wild-type mice, whereas deletion of STAT2 did not change fungal burden or airway neutrophilia compared with wild-type mice. These data demonstrate a mechanism by which influenza A-induced STAT1 signaling inhibits neutrophil recruitment and increases susceptibility to postinfluenza invasive pulmonary aspergillosis.

Acute respiratory virus infection (ARI) induces CD8 T cells with diminished cytokine production and functional impairment. The role of cellular mediators of immune impairment, specifically CD4 regulatory T cells (Tregs), is incompletely understood in ARI. Tregs are known suppressors of effector T cell function, but whether they are detrimental or beneficial in ARI remains controversial. We show in this paper that Treg depletion leads to increased CD8 T cell function and lower virus titer in mice infected with human metapneumovirus. We further demonstrate that Tregs play a temporal role in the immune response to human metapneumovirus and influenza: Treg depletion before infection pathologically reduces virus-specific CD8 T cell numbers and delays virus clearance, whereas depletion 2 d postinoculation enhances CD8 T cell functionality without reducing virus-specific CD8 T cell numbers. Mechanistically, Treg depletion during immune priming led to impaired dendritic cell and CD8 T cell migration. Further, early Treg depletion was associated with immune skewing toward a type 2 phenotype characterized by increased type 2 innate lymphoid cells and T2 CD4 T cells, which was not observed when Treg depletion was delayed until after inoculation. These results indicate that the presence of Tregs at inoculation is critical for efficient priming of the CD8 T cell response to ARI, whereas later in infection, Tregs are dispensable for virus clearance.

Disruptions to the maternally inherited allele UBE3A, encoding for an E3 ubiquitin ligase, leads to the manifestation of Angelman Syndrome (AS). While this disorder is rare, the symptoms are severe and lifelong including but not limited to: intractable seizures, abnormal EEG's, ataxic gait, lack of speech, and most notably an abnormally happy demeanor with easily provoked laughter. Currently, little is known about the neurophysiological underpinnings of UBE3A leading to such globally severe phenotypes. Utilizing the newest AS rat model, comprised of a full UBE3A deletion, we aimed to elucidate novel mechanistic actions and potential therapeutic targets. This report demonstrates for the first time that catalytically active UBE3A protein is detectable within cerebrospinal fluid (CSF) of wild type rats but distinctly absent in AS rat CSF. Microdialysis within the rat hippocampus also showed that UBE3A protein is located in the interstitial fluid of wild type rat brains but absent in AS animals. This protein maintains catalytic activity and appears to be regulated in a dynamic activity‐dependent manner. Lay Summary Angelman syndrome (AS) is a rare genetic disorder caused by the loss of the UBE3A gene within the central nervous system. Although we have identified the gene responsible for AS, we still have a long way to go to fully understand its function in vivo. Here we report that UBE3A is present within normal cerebrospinal fluid (CSF) but distinctly absent in AS CSF. Furthermore, we demonstrate that UBE3A is secreted and that this may occur in a dynamic activity‐dependent fashion. Extracellular UBE3A maintained its ubiquitinating activity, thus suggesting that UBE3A may have a novel role outside of neurons. Autism Res 2021, 14: 645–655. © 2021 International Society for Autism Research and Wiley Periodicals LLC

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