Role of ATG16L1 in Uropathogenic E. Coli Pathogenesis

Urinary tract infections (UTIs) are among the most common infectious diseases and are primarily caused by uropathogenic E. coli (UPEC). Given the greater incidence of antibiotic resistance among UPEC isolates, it is vital to determine factors and pathways important for an effective host response to UPEC in order to improve therapeutic options for combating UTIs. Autophagy is a cellular degradation pathway that plays important roles in pathogen control and modulation of innate immunity. One essential autophagy protein, ATG16L1, has been further implicated in controlling inflammation due to a common variant of ATG16L1 being associated with increased risk of Crohns disease, a disease of continuous excessive inflammation in the gut. Autophagy and ATG16L1 had been shown to play anti-pathogenic roles in response to a number of infections, yet little was known about their role in response to UPEC. In this thesis, I examined the role of ATG16L1 in response to UPEC pathogenesis. We found ATG16L1-deficient mice clear bacteriuria faster, recruit more monocytes/macrophages, and recover their epithelial barrier faster than WT mice in a well-established mouse model of UPEC induced UTI. ATG16L1 deficiency in the urothelium led to altered urothelial cell architecture, with accumulations of lysosomes and multivesicular bodies, and fewer UPEC quiescent intracellular reservoirs that can seed recurrent infections. Additionally, we found that immune cells lacking ATG16L1 were better able to clear their infection. Furthermore, ATG16L1 deficient macrophages were particularly adept at clearing their bacteria load. My work has revealed that ATG16L1-deficiency in fact improves the ability of macrophages derived from the bones of mice to take up more UPEC and enhances their secretion of IL-1, a key pro-inflammatory cytokine, in response to UPEC. This increased IL-1 secretion by ATG16L1-deficient macrophages in response to UPEC was dependent on enhanced cleavage of pro-IL-1 to its active form by activated caspase-1 and the NLRP3 inflammasome. Finally, to confirm that enhanced IL-1 secretion was the key mechanism for UTI clearance in ATG16L1-deficient mice, I determined that the mutant mice secreted more IL-1 in their urine in response to UPEC infection, and inhibition of IL-1 signaling abrogated the ATG16L1-deficiency dependent protection from UTIs. Together, my work suggests that ATG16L1 dampens what is otherwise a protective increase in macrophage recruitment and IL-1 production in response to UPEC infection. Thus, ATG16L1 deficiency improved the host response to UPEC infection, challenging the paradigm that deficiency in autophagy proteins is detrimental to the host. Furthermore, the detrimental ATG16L1-deficiency induced inflammation against commensal bacteria that is associated with Crohns disease may be the trade off for enhanced protection against acute infection and reservoir formation by UPEC and possibly other common infections

ATG16L1 and pathogenesis of urinary tract infections

Autophagy is generally considered to be antipathogenic. The autophagy gene ATG16L1 has a commonly occurring mutation associated with Crohn disease (CD) and intestinal cell abnormalities. Mice hypomorphic for ATG16L1 (ATG16L1(HM)) recreate specific features of CD. Our recent study shows that the same ATG16L1(HM) mice that are susceptible to intestinal inflammatory disease are protected from urinary tract infections (UTI), a common and important human disease primarily caused by uropathogenic E. coli (UPEC). UPEC colonize the bladder and exhibit both luminal and intra-epithelial stages. The host responds by recruiting innate immune cells and shedding infected epithelial cells to clear infection. Despite these countermeasures, UPEC can persist within the bladder epithelium as membrane-enclosed quiescent intracellular reservoirs (QIRs) that can seed recurrent UTI. The mechanisms of persistence remain unknown. In this study, we show that ATG16L1 deficiency protects the host against acute UTI and UPEC latency. ATG16L1(HM) mice clear urinary bacterial loads more rapidly and thoroughly due to ATG16L1-deficient innate immune components. Furthermore, ATG16L1(HM) mice exhibit superficial urothelial cell-autonomous architectural aberrations that also result in significantly reduced QIR numbers. Our findings reveal a host-protective effect of ATG16L1 deficiency in vivo against a common pathogen

Bumblebees negotiate a trade-off between nectar quality and floral biomechanics

How and why pollinators choose which flowers to visit are fundamental, multifaceted questions in pollination biology, yet most studies of floral traits measure simple relative preferences. Here, we used vertically and horizontally oriented slippery-surfaced artificial flowers to test whether bumblebees could make a trade-off between floral handling difficulty and nectar sucrose concentration. We quantified foraging energetics, thereby resolving the rationale behind the bees’ foraging decisions. The bees chose flowers with either a high handling cost or low sucrose concentration, depending on which was the energetically favorable option. Their behavior agreed with the critical currency being the rate of energy return (net energy collected per unit time), not energetic efficiency (net energy collected per unit energy spent). This suggests that bumblebees prioritize immediate carbohydrate flow to the nest rather than energy gain over the working lifespan of each bee. Trade-off paradigms like these are a powerful approach for quantifying pollinator trait preferences

Estrogenic modulation of uropathogenic Escherichia coli infection pathogenesis in a murine menopause model

Recurrent urinary tract infections (UTIs), primarily caused by uropathogenic Escherichia coli (UPEC), annually affect over 13 million patients in the United States. Menopausal women are disproportionally susceptible, suggesting estrogen deficiency is a significant risk factor for chronic and recurrent UTI. How estrogen status governs susceptibility to UTIs remains unknown, and whether hormone therapy protects against UTIs remains controversial. Here, we used a mouse model of surgical menopause by ovariectomy and demonstrate a protective role for estrogen in UTI pathogenesis. We found that ovariectomized mice had significantly higher bacteriuria, a more robust inflammatory response, and increased production of the proinflammatory cytokine interleukin-6 (IL-6) upon UPEC infection compared to sham-operated controls. We further show that response of the urothelial stem cell niche to infection, normally activated to restore homeostasis after infection, was aberrant in ovariectomized mice with defective superficial urothelial cell differentiation. Finally, UPEC-infected ovariectomized mice showed a significant increase in quiescent intracellular bacterial reservoirs, which reside in the urothelium and can seed recurrent infections. Importantly, this and other ovariectomy-induced outcomes of UTI were reversible upon estrogen supplementation. Together, our findings establish ovariectomized mice as a model for UTIs in menopausal women and pinpoint specific events during course of infection that are most susceptible to estrogen deficiency. These findings have profound implications for the understanding of the role of estrogen and estrogen therapy in bladder health and pathogen defense mechanisms and open the door for prophylaxis for menopausal women with recurrent UTIs

The usefulness of a science degree : the "lost voices" of science trained professionals

This paper reports a study of science graduates who are employed in positions outside their discipline specialisation. The research was designed to uncover the reasons for them choosing to study science at university, the competencies they utilise in their work and their lives, and how these relate to their undergraduate education in science. The study is seen as important in that already about one-half of science graduates are in such positions and it is argued that there is a need in scientific and technologically based societies to have a greater representation of such people in decision-making positions in government and industry. The directions for the science degree that can be drawn from the data gathered are congruent with those arising from other relevant studies. That is, attention should be paid to widely used skills, such as communication and problem-solving, and to developing an understanding of science within its social and ethical context. An argument is mounted for considering the way the science degree is presented to potential students and to the general public

Comparison of the normal state properties of κ\kappa-(BEDT-TTF)2_2Cu(NCS)2_2 and its deuterated analogue in high magnetic fields and under high hydrostatic pressures

Details of the Fermi-surface topology of deuterated $\kappa$-(BEDT-TTF)$_2$Cu(NCS)$_2$ ~have been measured as a function of pressure, and compared with equivalent measurements of the undeuterated salt. We find that the superconducting transition temperature is much more dramatically suppressed by increasing pressure in the deuterated salt. It is suggested that this is linked to pressure-induced changes in the Fermi-surface topology, which occur more rapidly in the deuterated salt than in the undeuterated salt as the pressure is raised. Our data suggest that the negative isotope effect observed on deuteration is due to small differences in Fermi-surface topology caused by the isotopic substitution.Comment: 10 pages 3 figure

High risk clinical characteristics for subarachnoid haemorrhage in patients with acute headache: prospective cohort study

Objective To identify high risk clinical characteristics for subarachnoid haemorrhage in neurologically intact patients with headache

Sensitivity of computed tomography performed within six hours of onset of headache for diagnosis of subarachnoid haemorrhage: prospective cohort study

Objective To measure the sensitivity of modern third generation computed tomography in emergency patients being evaluated for possible subarachnoid haemorrhage, especially when carried out within six hours of headache onset

Improving the outcome of infants born at <30 weeks' gestation - a randomized controlled trial of preventative care at home

Background: Early developmental interventions to prevent the high rate of neurodevelopmental problems in very preterm children, including cognitive, motor and behavioral impairments, are urgently needed. These interventions should be multi-faceted and include modules for caregivers given their high rates of mental health problems

Transcriptomic analysis supports similar functional roles for the two thymuses of the tammar wallaby

Background: The thymus plays a critical role in the development and maturation of T-cells. Humans have a single thoracic thymus and presence of a second thymus is considered an anomaly. However, many vertebrates have multiple thymuses. The tammar wallaby has two thymuses: a thoracic thymus (typically found in all mammals) and a dominant cervical thymus. Researchers have known about the presence of the two wallaby thymuses since the 1800s, but no genome-wide research has been carried out into possible functional differences between the two thymic tissues. Here, we used pyrosequencing to compare the transcriptomes of a cervical and thoracic thymus from a single 178 day old tammar wallaby.Results: We show that both the tammar thoracic and the cervical thymuses displayed gene expression profiles consistent with roles in T-cell development. Both thymuses expressed genes that mediate distinct phases of T-cells differentiation, including the initial commitment of blood stem cells to the T-lineage, the generation of T-cell receptor diversity and development of thymic epithelial cells. Crucial immune genes, such as chemokines were also present. Comparable patterns of expression of non-coding RNAs were seen. 67 genes differentially expressed between the two thymuses were detected, and the possible significance of these results are discussed.Conclusion: This is the first study comparing the transcriptomes of two thymuses from a single individual. Our finding supports that both thymuses are functionally equivalent and drive T-cell development. These results are an important first step in the understanding of the genetic processes that govern marsupial immunity, and also allow us to begin to trace the evolution of the mammalian immune system