Mucosal-associated invariant T cell regulation by bacterial signalling and immunometabolism

Mucosal-associated invariant T (MAIT) cells are a subset of antibacterial innate-like T cells that are localised to mucosal surfaces. MAIT cells are characterised by the expression of a semi-invariant T cell receptor, specific to a bacterial antigen presented on the MHC class I related protein, MR1. The bacterial ligand is derived from 5-amino-6-D-ribitylaminouracil (5-A-RU), produced as an intermediate in the bacterial riboflavin synthesis pathway. 5-A-RU undergoes non-enzymatic condensation with methylglyoxal (MG), a glycolysis by-product, to form the final ligand, 5 (2-oxopropylideneamino)-6-D-ribitylaminouracil (5-OP-RU). Presentation of 5 OP RU to MAIT cells stimulates a robust MAIT cell response. Given the abundance of MAIT cells at mucosal surfaces and the broad range of bacteria capable of activating them, it has been hypothesised that MAIT cell activation is tightly regulated to prevent hyperactivation and immunopathology. Understanding these regulatory mechanisms may enable modulation of MAIT cells to prevent or treat human disease. Here I show that both phagocytosis of bacteria by an antigen presenting cell (APC) and enhanced glycolysis regulate MAIT cell activation. To assess this, THP-1 cells, a monocytic cell line, served as APCs. THP-1 cells were incubated with glycolysis modulators, exogenous ligand, and non-ligand producing bacteria. Primary human MAIT cells were subsequently co-cultured with THP-1 cells and activation assessed by flow cytometry. Treatment with intact bacteria and 5-A-RU was found to activate MAIT cells to a greater extent than treatment with 5-A-RU alone or with lysed bacteria. Enhancement of THP 1 glycolysis augmented MAIT cell activation to 5-A-RU alone or 5-A-RU and lysed bacteria. In contrast, a reduction in activation was not observed when THP-1 cell glycolysis or PI3K, mTORC1, and mTORC2 signalling were inhibited. Furthermore, THP-1 cells did not exhibit increased glucose uptake upon stimulation with intact bacteria. These results suggest that phagocytosis of intact bacteria may enhance glycolysis, resulting in increased production of MG and formation of 5-OP-RU. However, further research is required to confirm this. The process described provides a potential regulatory mechanism by which MAIT cell activation is regulated in response to intact bacteria but not to soluble bacteria-derived 5-A-RU

Is it possible to extend IPv6?

The IPv6 Hop-by-Hop Options and Destination Options Extension Headers have historically faced challenges in deployment due to a lack of router support coupled with concerns around potential for denial-of-service attacks. However, there has been a renewed interest within the standards community both in simplifying their processing, and in using these extension headers for new applications. Through a wide-scale measurement campaign, we show that many autonomous systems in both access networks and the core of the Internet do permit the traversal of packets that include options, and that the path traversal currently depends on the type of network, size of the option and the transport protocol used, but does not usually depend on the type of included option. This is an encouraging result when considering the extensibility of IPv6. We show that packets that include an extension header can also impact the function of load balancing network devices, and present evidence of equipment mis-configuration, noting that a different path to the same destination can result in a different traversal result. Finally, we outline the current deployment challenges and provide recommendations for how extension headers can utilise options to extend IPv6

Trajectories of change in well-being during cognitive-behavior therapies for anxiety disorders: quantifying the impact and covariation with improvements in anxiety

Despite substantial evidence supporting the efficacy of cognitive behavioral therapy for reducing many forms of mental illness, less is known about whether CBT also promotes mental health or well being. We will discuss results of a recent study (Gallagher et al., 2019) examining changes in well being d uring different CBT treatments for anxiety disorders and how these changes relate to anxiety. In that study, 223 adults (55.6% female, Mage=31.1 yrs) were randomized to one of five CBT protocols for anxiety disorders at an outpatient clinic. Effect sizes w ere calculated to examine the timing and magnitude of changes in well being as a result of CBT. Further, parallel process latent growth curve models were conducted to examine the extent to which trajectories of changes in well being correlated with the tra jectories of change in both clinician rated and self reported anxiety during active treatment. Results indicated that there were moderate to large increases in overall well being and the three components of subjective, psychological, and social well being, mainly during the second half of CBT, and these increases were maintained at a 6 month follow up. Further, trajectories of change in well being across treatment were strongly correlated with trajectories of change in clinician rated and self reported anxi ety. Together, these findings suggest that different CBT protocols for anxiety consistently produce robust and lasting changes in different domains of positive mental health and increases in well being are strongly linked to changes in anxiety during treatment.Published versio

The clinical course of acute otitis media in high-risk Australian Aboriginal children: a longitudinal study

BACKGROUND: It is unclear why some children with acute otitis media (AOM) have poor outcomes. Our aim was to describe the clinical course of AOM and the associated bacterial nasopharyngeal colonisation in a high-risk population of Australian Aboriginal children. METHODS: We examined Aboriginal children younger than eight years who had a clinical diagnosis of AOM. Pneumatic otoscopy and video-otoscopy of the tympanic membrane (TM) and tympanometry was done every weekday if possible. We followed children for either two weeks (AOM without perforation), or three weeks (AOM with perforation), or for longer periods if the infection persisted. Nasopharyngeal swabs were taken at study entry and then weekly. RESULTS: We enrolled 31 children and conducted a total of 219 assessments. Most children had bulging of the TM or recent middle ear discharge at diagnosis. Persistent signs of suppurative OM (without ear pain) were present in most children 7 days (23/30, 77%), and 14 days (20/26, 77%) later. Episodes of AOM did not usually have a sudden onset or short duration. Six of the 14 children with fresh discharge in their ear canal had an intact or functionally intact TM. Perforation size generally remained very small (<2% of the TM). Healing followed by re-perforation was common. Ninety-three nasophyngeal swabs were taken. Most swabs cultured Streptococcus pneumoniae (82%), Haemophilus influenzae (71%), and Moraxella catarrhalis (95%); 63% of swabs cultured all three pathogens. CONCLUSION: In this high-risk population, AOM was generally painless and persistent. These infections were associated with persistent bacterial colonisation of the nasopharynx and any benefits of antibiotics were modest at best. Systematic follow up with careful examination and review of treatment are required and clinical resolution cannot be assumed

RhoE Is Regulated by Cyclic AMP and Promotes Fusion of Human BeWo Choriocarcinoma Cells

Fusion of placental villous cytotrophoblasts with the overlying syncytiotrophoblast is essential for the maintenance of successful pregnancy, and disturbances in this process have been implicated in pathological conditions such as pre-eclampsia and intra-uterine growth retardation. In this study we examined the role of the Rho GTPase family member RhoE in trophoblast differentiation and fusion using the BeWo choriocarcinoma cell line, a model of villous cytotrophoblast fusion. Treatment of BeWo cells with the cell permeable cyclic AMP analogue dibutyryl cyclic AMP (dbcAMP) resulted in a strong upregulation of RhoE at 24h, coinciding with the onset of fusion. Using the protein kinase A (PKA)-specific cAMP analogue N6-phenyl-cAMP, and a specific inhibitor of PKA (14–22 amide, PKI), we found that upregulation of RhoE by cAMP was mediated through activation of PKA signalling. Silencing of RhoE expression by RNA interference resulted in a significant decrease in dbcAMP-induced fusion. However, expression of differentiation markers human chorionic gonadotrophin and placental alkaline phosphatase was unaffected by RhoE silencing. Finally, we found that RhoE upregulation by dbcAMP was significantly reduced under hypoxic conditions in which cell fusion is impaired. These results show that induction of RhoE by cAMP is mediated through PKA and promotes BeWo cell fusion but has no effect on functional differentiation, supporting evidence that these two processes may be controlled by separate or diverging pathways

Evaluating the Effects of SARS-CoV-2 Spike Mutation D614G on Transmissibility and Pathogenicity.

Global dispersal and increasing frequency of the SARS-CoV-2 spike protein variant D614G are suggestive of a selective advantage but may also be due to a random founder effect. We investigate the hypothesis for positive selection of spike D614G in the United Kingdom using more than 25,000 whole genome SARS-CoV-2 sequences. Despite the availability of a large dataset, well represented by both spike 614 variants, not all approaches showed a conclusive signal of positive selection. Population genetic analysis indicates that 614G increases in frequency relative to 614D in a manner consistent with a selective advantage. We do not find any indication that patients infected with the spike 614G variant have higher COVID-19 mortality or clinical severity, but 614G is associated with higher viral load and younger age of patients. Significant differences in growth and size of 614G phylogenetic clusters indicate a need for continued study of this variant

End-Stage Renal Disease Among HIV-Infected Adults in North America

Background. Human immunodeficiency virus (HIV)-infected adults, particularly those of black race, are at high-risk for end-stage renal disease (ESRD), but contributing factors are evolving. We hypothesized that improvements in HIV treatment have led to declines in risk of ESRD, particularly among HIV-infected blacks

Genomic epidemiology of SARS-CoV-2 in a UK university identifies dynamics of transmission

AbstractUnderstanding SARS-CoV-2 transmission in higher education settings is important to limit spread between students, and into at-risk populations. In this study, we sequenced 482 SARS-CoV-2 isolates from the University of Cambridge from 5 October to 6 December 2020. We perform a detailed phylogenetic comparison with 972 isolates from the surrounding community, complemented with epidemiological and contact tracing data, to determine transmission dynamics. We observe limited viral introductions into the university; the majority of student cases were linked to a single genetic cluster, likely following social gatherings at a venue outside the university. We identify considerable onward transmission associated with student accommodation and courses; this was effectively contained using local infection control measures and following a national lockdown. Transmission clusters were largely segregated within the university or the community. Our study highlights key determinants of SARS-CoV-2 transmission and effective interventions in a higher education setting that will inform public health policy during pandemics.</jats:p

Hospital admission and emergency care attendance risk for SARS-CoV-2 delta (B.1.617.2) compared with alpha (B.1.1.7) variants of concern: a cohort study

Background: The SARS-CoV-2 delta (B.1.617.2) variant was first detected in England in March, 2021. It has since rapidly become the predominant lineage, owing to high transmissibility. It is suspected that the delta variant is associated with more severe disease than the previously dominant alpha (B.1.1.7) variant. We aimed to characterise the severity of the delta variant compared with the alpha variant by determining the relative risk of hospital attendance outcomes. Methods: This cohort study was done among all patients with COVID-19 in England between March 29 and May 23, 2021, who were identified as being infected with either the alpha or delta SARS-CoV-2 variant through whole-genome sequencing. Individual-level data on these patients were linked to routine health-care datasets on vaccination, emergency care attendance, hospital admission, and mortality (data from Public Health England's Second Generation Surveillance System and COVID-19-associated deaths dataset; the National Immunisation Management System; and NHS Digital Secondary Uses Services and Emergency Care Data Set). The risk for hospital admission and emergency care attendance were compared between patients with sequencing-confirmed delta and alpha variants for the whole cohort and by vaccination status subgroups. Stratified Cox regression was used to adjust for age, sex, ethnicity, deprivation, recent international travel, area of residence, calendar week, and vaccination status. Findings: Individual-level data on 43 338 COVID-19-positive patients (8682 with the delta variant, 34 656 with the alpha variant; median age 31 years [IQR 17–43]) were included in our analysis. 196 (2·3%) patients with the delta variant versus 764 (2·2%) patients with the alpha variant were admitted to hospital within 14 days after the specimen was taken (adjusted hazard ratio [HR] 2·26 [95% CI 1·32–3·89]). 498 (5·7%) patients with the delta variant versus 1448 (4·2%) patients with the alpha variant were admitted to hospital or attended emergency care within 14 days (adjusted HR 1·45 [1·08–1·95]). Most patients were unvaccinated (32 078 [74·0%] across both groups). The HRs for vaccinated patients with the delta variant versus the alpha variant (adjusted HR for hospital admission 1·94 [95% CI 0·47–8·05] and for hospital admission or emergency care attendance 1·58 [0·69–3·61]) were similar to the HRs for unvaccinated patients (2·32 [1·29–4·16] and 1·43 [1·04–1·97]; p=0·82 for both) but the precision for the vaccinated subgroup was low. Interpretation: This large national study found a higher hospital admission or emergency care attendance risk for patients with COVID-19 infected with the delta variant compared with the alpha variant. Results suggest that outbreaks of the delta variant in unvaccinated populations might lead to a greater burden on health-care services than the alpha variant. Funding: Medical Research Council; UK Research and Innovation; Department of Health and Social Care; and National Institute for Health Research