Transmembrane mutations in Toll-like receptor 9 bypass the requirement for ectodomain proteolysis and induce fatal inflammation.

Recognition of nucleic acids as a signature of infection by Toll-like receptors (TLRs) 7 and 9 exposes the host to potential self-recognition and autoimmunity. It has been proposed that intracellular compartmentalization is largely responsible for reliable self versus nonself discrimination by these receptors. We have previously shown that TLR9 and TLR7 require processing prior to activation, which may further reinforce receptor compartmentalization and tolerance to self, yet this possibility remains untested. Here we report that residues within the TLR9 transmembrane (TM) region conferred the requirement for ectodomain proteolysis. TLR9 TM mutants responded to extracellular DNA, and mice expressing such receptors died from systemic inflammation and anemia. This inflammatory disease did not require lymphocytes and appeared to require recognition of self-DNA by dendritic cells. To our knowledge, these results provide the first demonstration that TLR-intrinsic mutations can lead to a break in tolerance.

The ubiquitin ligase parkin mediates resistance to intracellular pathogens.

Ubiquitin-mediated targeting of intracellular bacteria to the autophagy pathway is a key innate defence mechanism against invading microbes, including the important human pathogen Mycobacterium tuberculosis. However, the ubiquitin ligases responsible for catalysing ubiquitin chains that surround intracellular bacteria are poorly understood. The parkin protein is a ubiquitin ligase with a well-established role in mitophagy, and mutations in the parkin gene (PARK2) lead to increased susceptibility to Parkinson's disease. Surprisingly, genetic polymorphisms in the PARK2 regulatory region are also associated with increased susceptibility to intracellular bacterial pathogens in humans, including Mycobacterium leprae and Salmonella enterica serovar Typhi, but the function of parkin in immunity has remained unexplored. Here we show that parkin has a role in ubiquitin-mediated autophagy of M. tuberculosis. Both parkin-deficient mice and flies are sensitive to various intracellular bacterial infections, indicating parkin has a conserved role in metazoan innate defence. Moreover, our work reveals an unexpected functional link between mitophagy and infectious disease.

Olfactory bulb and hypothalamic acute-phase responses to influenza virus: effects of immunization.

BACKGROUND: Within hours of intranasal challenge, mouse-adapted H1N1 A/Puerto Rico/8/34 (PR8) influenza genomic RNA is found in the olfactory bulb (OB) and OB pro-inflammatory cytokines are up-regulated. Severing the olfactory tract delays the acute-phase response (APR) and the APR is attenuated by immunization. OBJECTIVES: To determine if immunization affects OB localization of influenza or the molecular brain mechanisms regulating APR. METHODS: Male mice were immunized with PR8 influenza, then OB viral RNA, APR, and influenza-related cytokine responses were determined after homologous viral challenge. RESULTS: Immunization did not prevent influenza OB viral invasion within 24 h of viral challenge. However, it greatly attenuated OB viral RNA 6 days after viral challenge and the APR including hypothermia and body weight loss responses. Within the OB, 24 h after influenza challenge, prior immunization blocked virus-induced up-regulation of toll-like receptor 7 and interferon (IFN) γ mRNAs. At this time, hypothalamic (HT) growth hormone-releasing hormone receptor and tumor necrosis factor-α mRNAs were greatly enhanced in immunized but not in positive control mice. By 6 days after viral challenge, OB and HT mRNAs returned towards baseline values. In the lung, mRNA up-regulation was greater than that in the brain and maximized 6 days after challenge. Lung IFNγ mRNA decreased at 24 h but increased 6 days after challenge in the positive compared to negative controls. Immunization prevented the up-regulation of most of the flu-related mRNAs measured in lungs. CONCLUSION: Collectively, these data suggest a role for OB and HT involvement in immunization protection against influenza infection.

Scientist Spotlights in Secondary Schools: Student Shifts in Multiple Measures Related to Science Identity after Receiving Written Assignments.

Based on theoretical frameworks of scientist stereotypes, possible selves, and science identity, written assignments were developed to teach science content through biographies and research of counter-stereotypical scientists-Scientist Spotlights (www.scientistspotlights.org). Previous studies on Scientist Spotlight assignments showed significant shifts in how college-level biology students relate to and describe scientists and in their performance in biology courses. However, the outcomes of Scientist Spotlight assignments in secondary schools were yet to be explored. In collaboration with 18 science teachers from 12 schools, this study assessed the impacts of Scientist Spotlight assignments for secondary school students. We used published assessment tools: Relatability prompt; Stereotypes prompt; and Performance/Competence, Interest, and Recognition (PCIR) instrument. Statistical analyses compared students' responses before and after receiving at least three Scientist Spotlight assignments. We observed significant shifts in students' relatability to and descriptions of scientists as well as other science identity measures. Importantly, disaggregating classes by implementation strategies revealed that students' relatability shifts were significant for teachers reporting in-class discussions and not significant for teachers reporting no discussions. Our findings raise questions about contextual and pedagogical influences shaping student outcomes with Scientist Spotlight assignments, like how noncontent Instructor Talk might foster student shifts in aspects of science identity.

Vagotomy attenuates brain cytokines and sleep induced by peripherally administered tumor necrosis factor-α and lipopolysaccharide in mice.

STUDY OBJECTIVE: Systemic tumor necrosis factor-α (TNF-α) is linked to sleep and sleep altering pathologies in humans. Evidence from animals indicates that systemic and brain TNF-α have a role in regulating sleep. In animals, TNF-α or lipopolysaccharide (LPS) enhance brain pro-inflammatory cytokine expression and sleep after central or peripheral administration. Vagotomy blocks enhanced sleep induced by systemic TNF-α and LPS in rats, suggesting that vagal afferent stimulation by TNF-α enhances pro-inflammatory cytokines in sleep-related brain areas. However, the effects of systemic TNF-α on brain cytokine expression and mouse sleep remain unknown. DESIGN: We investigated the role of vagal afferents on brain cytokines and sleep after systemically applied TNF-α or LPS in mice. MEASUREMENTS AND RESULTS: Spontaneous sleep was similar in vagotomized and sham-operated controls. Vagotomy attenuated TNF-α- and LPS-enhanced non-rapid eye movement sleep (NREMS); these effects were more evident after lower doses of these substances. Vagotomy did not affect rapid eye movement sleep responses to these substances. NREMS electroencephalogram delta power (0.5-4 Hz range) was suppressed after peripheral TNF-α or LPS injections, although vagotomy did not affect these responses. Compared to sham-operated controls, vagotomy did not affect liver cytokines. However, vagotomy attenuated interleukin-1 beta (IL-1ß) and TNF-α mRNA brain levels after TNF-α, but not after LPS, compared to the sham-operated controls. CONCLUSIONS: We conclude that vagal afferents mediate peripheral TNF-α-induced brain TNF-α and IL-1ß mRNA expressions to affect sleep. We also conclude that vagal afferents alter sleep induced by peripheral pro-inflammatory stimuli in mice similar to those occurring in other species.