Cummins, Nathan W.

ABSTRACT Underlying mechanisms of individual variation in severity of influenza infection and response to vaccination are poorly understood. We investigated the effect of reduced heme oxygenase‐1 (HO‐1) expression on vaccine response and outcome of influenza infection. HO‐1‐deficient and wild‐type (WT) mice (kingdom, Animalia; phylum, Chordata; genus/species, Mus musculus ) were infected with influenza virus A/PR/8/34 with or without prior vaccination with an adeno‐viral‐based influenza vaccine. A genome‐wide association study evaluated the expression of single‐nucleotide polymorphisms (SNPs) in the HO‐1 gene and the response to influenza vaccination in healthy humans. HO‐1‐deficient mice had decreased survival after influenza infection compared to WT mice (median survival 5.5 vs. 6.5 d, P =0.016). HO‐1‐deficient mice had impaired production of antibody following influenza vaccination compared to WT mice (mean antibody titer 869 vs. 1698, P =0.02). One SNP in HO‐1 and one SNP in the constitutively expressed isoform HO‐2 were independently associated with decreased antibody production after influenza vaccination in healthy human volunteers ( P =0.017 and 0.014, respectively). HO‐1 deficient mice were paired with sex‐ and age‐matched WT controls. HO‐1 affects the immune response to both influenza infection and vaccination, suggesting that therapeutic induction of HO‐1 expression may represent a novel adjuvant to enhance influenza vaccine effectiveness.—Cummins, N. W., Weaver, E. A., May, S. M., Croatt, A. J., Foreman, O., Kennedy, R. B., Poland, G. A., Barry, M. A., Nath, K. A., Badley, A. D. Heme oxygenase‐1 regulates the immune response to influenza virus infection and vaccination in aged mice. FASEB J. 26, 2911–2918 (2012). www.fasebj.org

Anaerobic gram-positive bacilli can occasionally be implicated in infections but are difficult to identify in culture by conventional biochemical methods. We report a case of liver abscesses caused byEggerthella lenta, identified via 16S rRNA sequencing in a previously healthy patient, successfully treated with percutaneous drainage and ertapenem.

ABSTRACT Casp8p41, a novel protein generated when HIV-1 protease cleaves caspase 8, independently causes NF-κB activation, proinflammatory cytokine production, and cell death. Here we investigate the mechanism by which Casp8p41 induces cell death. Immunogold staining and electron microscopy demonstrate that Casp8p41 localizes to mitochondria of activated primary CD4 T cells, suggesting mitochondrial involvement. Therefore, we assessed the dependency of Casp8p41-induced death on Bax/Bak and caspase 9. In wild-type (WT) mouse embryonic fibroblast (MEF) cells, Casp8p41 causes rapid mitochondrial depolarization ( P < 0.001), yet Casp8p41 expression in Bax/Bak double-knockout (DKO) MEF cells does not. Similarly, caspase 9-deficient T cells (JMR cells), which express Casp8p41, undergo minimal cell death, whereas reconstituting these cells with caspase 9 (F9 cells) restores Casp8p41 cytotoxicity ( P < 0.01). The infection of caspase 9-deficient cells with a green fluorescent protein (GFP) HIV-1 reporter virus results in cell death in 32% of infected GFP-positive cells, while the restoration of caspase 9 expression in these cells restores infected-cell killing to 68% ( P < 0.05), with similar levels of viral replication between infections. Our data demonstrate that Casp8p41 requires Bax/Bak to induce mitochondrial depolarization, which leads to caspase 9 activation following either Casp8p41 expression or HIV-1 infection. This understanding allows the design of strategies to interrupt this form of death of HIV-1-infected cells.