Expression of an IKKγ Splice Variant Determines IRF3 and Canonical NF-κB Pathway Utilization in ssRNA Virus Infection

Single stranded RNA (ssRNA) virus infection activates the retinoic acid inducible gene I (RIG-I)- mitochondrial antiviral signaling (MAVS) complex, a complex that coordinates the host innate immune response via the NF-kappaB and IRF3 pathways. Recent work has shown that the IkappaB kinase (IKK)gamma scaffolding protein is the final common adapter protein required by RIG-I.MAVS to activate divergent rate-limiting kinases downstream controlling the NF-kappaB and IRF3 pathways. Previously we discovered a ubiquitous IKKgamma splice-variant, IKKgammaDelta, that exhibits distinct signaling properties.We examined the regulation and function of IKKgamma splice forms in response to ssRNA virus infection, a condition that preferentially induces full length IKKgamma-WT mRNA expression. In IKKgammaDelta-expressing cells, we found increased viral translation and cytopathic effect compared to those expressing full length IKKgamma-WT. IKKgammaDelta fails to support viral-induced IRF3 activation in response to ssRNA infections; consequently type I IFN production and the induction of anti-viral interferon stimulated genes (ISGs) are significantly attenuated. By contrast, ectopic RIG-I.MAVS or TNFalpha-induced canonical NF-kappaB activation is preserved in IKKgammaDelta expressing cells. Increasing relative levels of IKKgamma-WT to IKKgammaDelta (while keeping total IKKgamma constant) results in increased type I IFN expression. Conversely, overexpressing IKKgammaDelta (in a background of constant IKKgamma-WT expression) shows IKKgammaDelta functions as a dominant-negative IRF3 signaling inhibitor. IKKgammaDelta binds both IKK-alpha and beta, but not TANK and IKKepsilon, indicating that exon 5 encodes an essential TANK binding domain. Finally, IKKgammaDelta displaces IKKgammaWT from MAVS explaining its domainant negative effect.Relative endogenous IKKgammaDelta expression affects cellular selection of inflammatory/anti-viral pathway responses to ssRNA viral infection

Henipavirus pathogenesis in human respiratory epithelial cells

Hendra virus (HeV) and Nipah virus (NiV) are deadly zoonotic viruses for which no vaccines or therapeutics are licensed for human use. Henipavirus infection causes severe respiratory illness and encephalitis. Although the exact route of transmission in human is unknown, epidemiological studies and in vivo studies suggest that the respiratory tract is important for virus replication. However, the target cells in the respiratory tract are unknown, as are the mechanisms by which henipaviruses can cause disease. In this study, we characterized henipavirus pathogenesis using primary cells derived from the human respiratory tract. The growth kinetics of NiV-Malaysia, NiV-Bangladesh, and HeV were determined in bronchial/ tracheal epithelial cells (NHBE) and small airway epithelial cells (SAEC). In addition, host responses to infection were assessed by gene expression analysis and immunoassays. Viruses replicated efficiently in both cell types and induced large syncytia. The host response to henipavirus infection in NHBE and SAEC highlighted a difference in the inflammatory response between HeV and NiV strains as well as intrinsic differences in the ability to mount an inflammatory response between NHBE and SAEC. These responses were highest during HeV infection in SAEC, as characterized by the levels of key cytokines (interleukin 6 [IL-6], IL-8, IL-1α, monocyte chemoattractant protein 1 [MCP-1], and colony-stimulating factors) responsible for immune cell recruitment. Finally, we identified virus strain-dependent variability in type I interferon antagonism in NHBE and SAEC: NiV-Malaysia counteracted this pathway more efficiently than NiV-Bangladesh and HeV. These results provide crucial new information in the understanding of henipavirus pathogenesis in the human respiratory tract at an early stage of infection

Production of chromophoric dissolved organic matter (CDOM) in the open ocean by zooplankton and the colonial cyanobacterium Trichodesmium spp.

Chromophoric (or colored) dissolved organic matter (CDOM) has been identified as a major determinant of the optical properties of oligotrophic oceans. The factors controlling distribution of CDOM far from the direct influence of land are not well known, as CDOM abundance and distribution does not directly correlate with phytoplankton productivity or biomass, or with dissolved organic matter (DOM) concentration. As part of a larger study of the dynamics of CDOM in the open ocean, we investigated direct release from plankton as a factor contributing to distribution patterns of CDOM. We measured the production of CDOM by zooplankton (copepods, euphausiids, amphipods, salps, polychaetes), protozoans (colonial radiolaria), and by the colonial cyanobacterium Trichodesmium spp. in the North Atlantic subtropical gyre. Groups of individual species of plankton were incubated and absorption spectra were obtained for their release products. CDOM was produced by all organisms examined, and absorption spectra varied by taxa, with major taxa exhibiting characteristic absorption peaks. Plankton-produced DOM is a source of labile carbon and thus facilitates microbial activity, and CDOM may also serve as photoprotection for near-surface-living organisms. Zooplankton likely play an important role in the CDOM cycle in the Sargasso Sea, directly through release/excretion of CDOM and indirectly by providing a labile substrate (excretia) for microbial-mediated production of CDOM

Variable penetrance of metabolic phenotypes and development of high-fat diet-induced adiposity in NEIL1-deficient mice

Exposure to chronic and acute oxidative stress is correlated with many human diseases, including, but not limited to, cancer, heart disease, diabetes, and obesity. In addition to cellular lipids and proteins, cellular oxidative stress can result in damage to DNA bases, especially in mitochondrial DNA. We previously described the development of spontaneous late-onset obesity, hepatic steatosis, hyperinsulinemia, and hyperleptinemia in mice that are deficient in the DNA glycosylase nei-like 1 (NEIL1), which initiates base excision repair of several oxidatively damaged bases. In the current study, we report that exposure to a chronic oxidative stress in the form of a high-fat diet greatly accelerates the development of obesity in neil1−/− mice. Following a 5-wk high-fat diet challenge, neil1−/− mice gained significantly more body weight than neil1+/+ littermates and had increased body fat accumulation and moderate to severe hepatic steatosis. Analysis of oxygen consumption by indirect calorimetry indicated a modest reduction in total oxygen consumption in neil1−/− mice that was abolished upon correction for lean body mass. Additionally, hepatic expression of several inflammatory genes was significantly upregulated in neil1−/− mice following high-fat diet challenge compared with chow-fed or neil1+/+ counterparts. A long-term high-fat diet also induced glucose intolerance as well as a significant reduction in mitochondrial DNA and protein content in neil1−/− mice. Collectively, these data indicate that NEIL1 deficiency results in an increased susceptibility to obesity and related complications potentially by lowering the threshold for tolerance of cellular oxidative stress in neil1−/− mice

Differential Responses of Human Fetal Brain Neural Stem Cells to Zika Virus Infection

Zika virus (ZIKV) infection causes microcephaly in a subset of infants born to infected pregnant mothers. It is unknown whether human individual differences contribute to differential susceptibility of ZIKV-related neuropathology. Here, we use an Asian-lineage ZIKV strain, isolated from the 2015 Mexican outbreak (Mex1-7), to infect primary human neural stem cells (hNSCs) originally derived from three individual fetal brains. All three strains of hNSCs exhibited similar rates of Mex1-7 infection and reduced proliferation. However, Mex1-7 decreased neuronal differentiation in only two of the three stem cell strains. Correspondingly, ZIKA-mediated transcriptome alterations were similar in these two strains but significantly different from that of the third strain with no ZIKV-induced neuronal reduction. This study thus confirms that an Asian-lineage ZIKV strain infects primary hNSCs and demonstrates a cell-strain-dependent response of hNSCs to ZIKV infection

How frequent is routine use of probiotics in UK neonatal units?

Objective There is a lack of UK guidance regarding routine use of probiotics in preterm infants to prevent necrotising enterocolitis, late-onset sepsis and death. As practices can vary, we aimed to determine the current usage of probiotics within neonatal units in the UK.Design and setting Using NeoTRIPS, a trainee-led neonatal research network, an online survey was disseminated to neonatal units of all service levels within England, Scotland, Northern Ireland and Wales in 2022. Trainees were requested to complete one survey per unit regarding routine probiotic administration.Results 161 of 188 (86%) neonatal units responded to the survey. 70 of 161 (44%) respondents routinely give probiotics to preterm infants. 45 of 70 (64%) use the probiotic product Lactobacillus acidophilus NCFM/Bifidobacterium bifidum Bb-06/B. infantis Bi-26 (Labinic™). 57 of 70 (81%) start probiotics in infants ≤32 weeks’ gestation. 33 of 70 (47%) had microbiology departments that were aware of the use of probiotics and 64 of 70 (91%) had a guideline available. Commencing enteral feeds was a prerequisite to starting probiotics in 62 of 70 (89%) units. The majority would stop probiotics if enteral feeds were withheld (59 of 70; 84%) or if the infant was being treated for necrotising enterocolitis (69 of 70; 99%). 24 of 91 (26%) units that did not use probiotics at the time of the survey were planning to introduce them within the next 12 months.Conclusions More than 40% of all UK neonatal units that responded are now routinely administering probiotics, with variability in the product used. With increased probiotic usage in recent years, there is a need to establish whether this translates to improved clinical outcomes