Streptolysin S is required for Streptococcus pyogenes nasopharyngeal and skin infection in HLA-transgenic mice.

Streptococcus pyogenes is a human-specific pathogen that commonly colonizes the upper respiratory tract and skin, causing a wide variety of diseases ranging from pharyngitis to necrotizing fasciitis and toxic shock syndrome. S. pyogenes has a repertoire of secreted virulence factors that promote infection and evasion of the host immune system including the cytolysins streptolysin O (SLO) and streptolysin S (SLS). S. pyogenes does not naturally infect the upper respiratory tract of mice although mice transgenic for MHC class II human leukocyte antigens (HLA) become highly susceptible. Here we used HLA-transgenic mice to assess the role of both SLO and SLS during both nasopharyngeal and skin infection. Using S. pyogenes MGAS8232 as a model strain, we found that an SLS-deficient strain exhibited a 100-fold reduction in bacterial recovery from the nasopharynx and a 10-fold reduction in bacterial burden in the skin, whereas an SLO-deficient strain did not exhibit any infection defects in these models. Furthermore, depletion of neutrophils significantly restored the bacterial burden of the SLS-deficient bacteria in skin, but not in the nasopharynx. In mice nasally infected with the wildtype S. pyogenes, there was a marked change in localization of the tight junction protein ZO-1 at the site of infection, demonstrating damage to the nasal epithelia that was absent in mice infected with the SLS-deficient strain. Overall, we conclude that SLS is required for the establishment of nasopharyngeal infection and skin infection in HLA-transgenic mice by S. pyogenes MGAS8232 and provide evidence that SLS contributes to nasopharyngeal infection through the localized destruction of nasal epithelia.

Global pannexin 1 deletion increases tumor-infiltrating lymphocytes in the BRAF/Pten mouse melanoma model.

Immunotherapies for malignant melanoma seek to boost the anti-tumoral response of CD8+ T cells, but have a limited patient response rate, in part due to limited tumoral immune cell infiltration. Genetic or pharmacological inhibition of the pannexin 1 (PANX1) channel-forming protein is known to decrease melanoma cell tumorigenic properties in vitro and ex vivo. Here, we crossed Panx1 knockout (Panx1-/-) mice with the inducible melanoma model BrafCA, PtenloxP, Tyr::CreERT2 (BPC). We found that deleting the Panx1 gene in mice does not reduce BRAF(V600E)/Pten-driven primary tumor formation or improve survival. However, tumors in BPC-Panx1-/- mice exhibited a significant increase in the infiltration of CD8+ T lymphocytes, with no changes in the expression of early T-cell activation marker CD69, lymphocyte activation gene 3 protein (LAG-3) checkpoint receptor, or programmed cell death ligand-1 (PD-L1) in tumors when compared to the BPC-Panx1+/+ genotype. Our results suggest that, although Panx1 deletion does not overturn the aggressive BRAF/Pten-driven melanoma progression in vivo, it does increase the infiltration of effector immune T-cell populations in the tumor microenvironment. We propose that PANX1-targeted therapy could be explored as a strategy to increase tumor-infiltrating lymphocytes to boost anti-tumor immunity.

Systemic administration of anti-CD20 indirectly reduces B cells in the inflamed meninges in a chronic model of central nervous system autoimmunity.

Anti-CD20 B cell depleting therapies have demonstrated that B cells are important drivers of disease progress in Multiple Sclerosis, although the pathogenic mechanisms are not well understood. A population of B cells accumulates in the inflamed meninges in MS and also some chronic animal models of disease, typically adjacent to demyelinating lesions. The role of these meningeal B cells in disease is not known, nor is their susceptibility to anti-CD20 therapy. Here, we administered anti-CD20 to 2D2 IgHMOG spontaneous experimental autoimmune encephalomyelitis mice in the chronic phase of disease, after the establishment of meningeal B cell clusters. Compared to the circulation, lymph nodes, and spleen, B cell depletion from the meninges was delayed and not evident until 7d post-administration of anti-CD20. Further, we did not find evidence that anti-CD20 accessed meningeal B cells directly, but rather that depletion was indirect and the result of ongoing turnover of the meningeal population and elimination of the peripheral pool from which it is sustained.

Socioeconomic, Behavioural, and Social Health Correlates of Optimism and Pessimism in Older Men and Women: A Cross-Sectional Study.

BACKGROUND: Optimism is a disposition characterised by positive future expectancies, while pessimism is characterised by expecting the worst. High optimism and low pessimism promote the health of older adults and may potentiate full engagement in life. We identified socioeconomic, behavioural, and social factors associated with optimism and pessimism in older adults. METHODS: Participants included 10,146 community-dwelling, apparently healthy Australian adults aged 70 years and over from the ASPREE Longitudinal Study of Older Persons (ALSOP). Optimism and pessimism were measured using the revised Life Orientation Test. Cross-sectional ordinal logistic regression was used to determine the socioeconomic, behavioural, and social health factors associated with optimism and pessimism. RESULTS: Higher education, greater physical activity, lower loneliness, and volunteering were associated with higher optimism and lower pessimism. Low social support was associated with higher pessimism. Higher socioeconomic advantage, greater income, and living alone were associated with lower pessimism. Women were more optimistic and less pessimistic than men. The association of age, smoking status, and alcohol consumption with optimism and pessimism differed for men and women. CONCLUSIONS: Factors associated with higher optimism and lower pessimism were also those demonstrated to support healthy ageing. Health-promotion action at the individual level (e.g., smoking cessation or regular physical activity), health professional level (e.g., social prescribing or improving access and quality of care for all older adults), and community level (e.g., opportunities for volunteer work or low-cost social activities for older adults) may improve optimism and reduce pessimism, possibly also promoting healthy ageing.

The Streptococcus pyogenes hyaluronic acid capsule promotes experimental nasal and skin infection by preventing neutrophil-mediated clearance.

Streptococcus pyogenes is a globally prominent human-specific pathogen responsible for an enormous burden of human illnesses, including >600 million pharyngeal and >100 million skin infections each year. Despite intensive efforts that focus on invasive indications, much remains unknown about this bacterium in its natural state during colonization of the nasopharynx and skin. Using acute experimental infection models in HLA-transgenic mice, we evaluated how the hyaluronic acid (HA) capsule contributes to S. pyogenes MGAS8232 infection within these limited biological niches. Herein, we demonstrate that HA capsule expression promotes bacterial burden in murine nasal turbinates and skin lesions by resisting neutrophil-mediated killing. HA capsule production is encoded by the hasABC operon and compared to wildtype S. pyogenes infections, mice infected with a ΔhasA mutant exhibited over a 1000-fold CFU reduction at 48-hours post-nasal challenge, and a 10,000-fold CFU reduction from skin lesions 72-hours post-skin challenge. HA capsule expression contributed substantially to skin lesion size development following subdermal inoculations. In the absence of capsule expression, S. pyogenes revealed drastically impeded growth in whole human blood and increased susceptibility to killing by isolated neutrophils ex vivo, highlighting its important role in resisting phagocytosis. Furthermore, we establish that neutrophil depletion in mice recovered the reduced burden by the ΔhasA mutant in both the nasopharynx and skin. Together, this work confirms that the HA capsule is a key virulence determinant during acute infections by S. pyogenes and demonstrates that its predominant function is to protect S. pyogenes against neutrophil-mediated killing.

Pre-Germinal Center Interactions with T Cells Are Natural Checkpoints to Limit Autoimmune B Cell Responses.

Interactions with Ag-specific T cells drive B cell activation and fate choices that ultimately determine the quality of high-affinity Ab responses. As such, these interactions, and especially the long-lived interactions that occur before germinal center formation, may be important checkpoints to regulate undesirable responses. Using mouse model Ag systems, we directly observed interactions between T and B cells responding to the self-antigen myelin oligodendrocyte glycoprotein (MOG) and found that they are of lower quality compared with interactions between cells responding to the model foreign Ag nitrophenyl-haptenated OVA. This was associated with reduced expression of molecules that facilitate these interactions on the B cells, but not on T cells. B cell expression of these molecules was not dictated by the T cell partner, nor could the relative lack of expression on MOG-specific (MOG-sp.) B cells be reversed by a multivalent Ag. Instead, MOG-sp. B cells were inherently less responsive to BCR stimulation than MOG-non-sp. cells. However, the phenotype of MOG-sp. B cells was not consistent with previous descriptions of autoimmune B cells that had been tolerized via regular exposure to systemically expressed self-antigen. This suggests that alternate anergy pathways may exist to limit B cell responses to tissue-restricted self-antigens.

The Association of Dispositional Optimism and Pessimism With Cardiovascular Disease Events in Older Adults: A Prospective Cohort Study.

Objective: Positive psychosocial factors may protect against cardiovascular disease (CVD). We aimed to determine the association of optimism and pessimism with CVD events in community-dwelling older adults. Methods: 11,651 adults aged 70 years and over, participants of the ASPREE Longitudinal Study of Older Persons (ALSOP), were followed-up for 4.7 years (median). The association of optimism and pessimism (assessed as separate constructs by revised Life Orientation Test) and incident CVD events (composite and components) was assessed by Cox regression adjusted for demographic, socioeconomic and health factors. Results: No association was observed between optimism and pessimism with composite CVD events. Being more pessimistic was associated with a greater risk of fatal coronary heart disease, while being more optimistic was associated with a lower risk of non-fatal myocardial infarction. Conclusions: Optimism and pessimism may shape cardiovascular health of older adults; and we argue these psychosocial factors should be researched as separate constructs.

Superantigens promote Staphylococcus aureus bloodstream infection by eliciting pathogenic interferon-gamma production.

Staphylococcus aureus is a foremost bacterial pathogen responsible for a vast array of human diseases. Staphylococcal superantigens (SAgs) constitute a family of exotoxins from S. aureus that bind directly to major histocompatibility complex (MHC) class II and T cell receptors to drive extensive T cell activation and cytokine release. Although these toxins have been implicated in serious disease, including toxic shock syndrome, the specific pathological mechanisms remain unclear. Herein, we aimed to elucidate how SAgs contribute to pathogenesis during bloodstream infections and utilized transgenic mice encoding human MHC class II to render mice susceptible to SAg activity. We demonstrate that SAgs contribute to S. aureus bacteremia by massively increasing bacterial burden in the liver, and this was mediated by CD4+ T cells that produced interferon gamma (IFN-γ) to high levels in a SAg-dependent manner. Bacterial burdens were reduced by blocking IFN-γ, phenocopying SAg-deletion mutant strains, and inhibiting a proinflammatory response. Infection kinetics and flow cytometry analyses suggested that this was a macrophage-driven mechanism, which was confirmed through macrophage-depletion experiments. Experiments in human cells demonstrated that excessive IFN-γ allowed S. aureus to replicate efficiently within macrophages. This indicates that SAgs promote bacterial survival by manipulating the immune response to inhibit effective clearing of S. aureus Altogether, this work implicates SAg toxins as critical therapeutic targets for preventing persistent or severe S. aureus disease.

Dispositional Optimism and All-Cause Mortality in Older Adults: A Cohort Study.

OBJECTIVE: Optimism is modifiable and may be associated with healthy aging. We aim to investigate whether dispositional optimism is associated with all-cause mortality in adults 70 years and older. METHODS: Between 2010 and 2014, older adults free of serious cardiovascular disease and dementia were recruited through primary care physicians and enrolled in the Aspirin Reducing Events in the Elderly (ASPREE) clinical trial. Australian ASPREE participants were invited to participate in the ASPREE Longitudinal Study of Older Persons (ALSOP) that was running in parallel to ASPREE. Optimism was assessed at baseline using the Life Orientation Test-Revised. The association between optimism, divided into quartiles, and all-cause mortality was assessed using Cox proportional hazards models. RESULTS: A total of 11,701 participants (mean [standard deviation] age = 75.1 [4.24] years; 46.6% men) returned the ALSOP Social questionnaire and completed the Life Orientation Test-Revised. During a median follow-up of 4.7 years, 469 deaths occurred. The fully adjusted model was not significant (hazard ratio = 0.78, 95% confidence interval = 0.58-1.06). There was evidence that age was an effect modifier of the association between optimism and longevity. Higher optimism was associated with lower mortality risk in the oldest individuals only (77+ years; hazard ratio = 0.61, 95% confidence interval = 0.39-0.96). CONCLUSIONS: We observed no independent relationship between optimism and all-cause mortality in the total sample, although optimism seemed to be associated with lower risk among the oldest old (adults 77 years and older).

The psychometric evaluation of the sense of belonging instrument (SOBI) with Iranian older adults.

BACKGROUND: A sense of belonging is a significant predictor of mental health and well-being in later life. A sense of belonging in childhood and adolescence contributes to a number of adult behavioural and psychological outcomes. A high sense of belonging has been associated with better health, longevity, psychological well-being, and disease recovery. METHODS: In this study, the Persian version of the Sense of Belonging Instrument (SOBI) for older adults in Iran was evaluated psychometrically to develop an accurate measure for belonging. Participants in the study were 302 older adults, 60 years old and above, living independently in Iran and chosen through convenience sampling. RESULTS: An exploratory factor analysis indicated that the four-factor structure, which included 16 items, accounted for 54.12% of the total variance, and was characterized by strong factor loadings, with values ranging from .50 to .87. Thereafter, a confirmatory factor analysis confirmed the four-factor latent structure of the SOBI, providing adequate data-model fit statistics. All latent structures were characterized by adequate-to-strong latent construct (H) internal reliability (α) coefficients. CONCLUSIONS: The Persian version of the SOBI is a useful tool in understanding older adult patients' sense of belonging when living independently within the community. The implications for practice and research are discussed.

Understanding urban accessibility: A community-engaged pilot study of entrance features.

The accessibility of the built environment is an equity issue. Accessibility standards for buildings exist, but often apply to new buildings or major renovations. This renders historic neighborhoods inaccessible. Accessibility standards and related assessments rarely consider the experiences and priorities of people who experience disability. Partnered with local government and an accessibility advisory committee, we conducted a pilot study of urban accessibility in Edmonton Edmon, Alberta, Canada. We measured four indicators of entranceway accessibility along a popular, central commercial corridor and mapped the data with building age using QGIS. We found significant accessibility barriers.

Quantifying National-Scale Changes in Agricultural Land Exposure to Fluvial Flooding.

This study quantifies the exposure of agricultural land in Aotearoa-New Zealand's (A-NZ) flood hazard zones (FHZs). We developed a spatio-temporal flood exposure framework to quantify the extent of the area and yearly earnings before income and tax (EBIT) for arable, forestry, horticulture, sheep and beef, and dairy land in FHZs between 1990 and 2016. In 1990, ~1.57 million hectares of agricultural land were exposed, decreasing slightly to ~1.50 million hectares by 2016. However, there was a change in the lower-value types of agricultural land uses being exposed, such as for sheep and beef farming and forestry, toward dairy farming (from ~364,000 hectares in FHZs in 2008 to ~471,000 hectares in 2016). Dairy farming is more intensively staffed with larger amounts of fixed assets, making them less resilient to flood impacts. Despite this, conversion to dairy farming even within the identified FHZs has been driven by the increasing profitability of the enterprise. As a result of both the production value change and land area increases, the dairy EBIT values within FHZs rose rapidly from NZD 382 million to NZD 1.25 billion between 2008 and 2012, creating significantly more economic exposure for A-NZ. This trend is particularly evident in the Southland, Canterbury, and Waikato regions. Similarly, in the Marlborough, Tasman, and Hawke's Bay regions, there was an increase in high-value horticultural land-predominantly viticulture-in FHZs (a increase of NZD 321 million in annual EBIT for exposed horticulture across the three regions). Identifying sub-national trends in agricultural flood exposure allows for a detailed analysis of the likely impacts in high-risk areas, which can inform emergency management plans and mitigative actions that diminish the economic impacts from flood events.

Quality of life and mortality in the general population: a systematic review and meta-analysis.

BACKGROUND: Quality of life (QoL) is multi-dimensional concept of an individual' general well-being status in relation to their value, environment, cultural and social context in which they live. This study aimed to quantitatively synthesise available evidence on the association between QoL and mortality in the general population. METHODS: An electronic search was conducted using three bibliographic databases, MEDLINE, EMBASE and PsycINFO. Inclusion criteria were studies that assessed QoL using standardized tools and examined mortality risk in a non-patient population. Qualitative data synthesis and meta-analyses using a random-effects model were performed. RESULTS: Of 4184 articles identified, 47 were eligible for inclusion, involving approximately 1,200,000 participants. Studies were highly heterogeneous in terms of QoL measures, population characteristics and data analysis. In total, 43 studies (91.5%) reported that better QoL was associated with lower mortality risk. The results of four meta-analyses indicated that higher health-related QoL (HRQoL) is associated with lower mortality risk, which was consistent for overall HRQoL (HR 0.633, 95% CI: 0.514 to 0.780), physical function (HR 0.987, 95% CI: 0.982 to 0.992), physical component score (OR 0.950, 95% CI: 0.935 to 0.965), and mental component score (OR 0.980, 95% CI: 0.969 to 0.992). CONCLUSION: These findings provide evidence that better QoL/HRQoL was associated with lower mortality risk. The utility of these measures in predicting mortality risk indicates that they should be considered further as potential screening tools in general clinical practice, beyond the traditional objective measures such as body mass index and the results of laboratory tests.

Autoreactive, Low-Affinity T Cells Preferentially Drive Differentiation of Short-Lived Memory B Cells at the Expense of Germinal Center Maintenance.

B cell fate decisions within a germinal center (GC) are critical to determining the outcome of the immune response to a given antigen. Here, we characterize GC kinetics and B cell fate choices in a response to the autoantigen myelin oligodendrocyte glycoprotein (MOG) and compare the response with a standard model foreign antigen. Both antigens generate productive primary responses, as evidenced by GC development, circulating antigen-specific antibodies, and differentiation of memory B cells. However, in the MOG response, the status of the cognate T cell partner drives preferential B cell differentiation to a memory phenotype at the expense of GC maintenance, resulting in a truncated GC. Reduced plasma cell differentiation is largely independent of T cell influence. Interestingly, memory-phenotype B cells formed in the MOG GC are not long lived, resulting in a failure of the B cell response to secondary challenge.

Meningeal Infiltration of the Spinal Cord by Non-Classically Activated B Cells is Associated with Chronic Disease Course in a Spontaneous B Cell-Dependent Model of CNS Autoimmune Disease.

We characterized B cell infiltration of the spinal cord in a B cell-dependent spontaneous model of central nervous system (CNS) autoimmunity that develops in a proportion of mice with mutant T and B cell receptors specific for myelin oligodendrocyte glycoprotein. We found that, while males are more likely to develop disease, females are more likely to have a chronic rather than monophasic disease course. B cell infiltration of the spinal cord was investigated by histology and FACs. CD4(+) T cell infiltration was pervasive throughout the white and in some cases gray matter. B cells were almost exclusively restricted to the meninges, often in clusters reminiscent of those described in human multiple sclerosis. These clusters were typically found adjacent to white matter lesions and their presence was associated with a chronic disease course. Extensive investigation of these clusters by histology did not identify features of lymphoid follicles, including organization of T and B cells into separate zones, CD35(+) follicular dendritic cells, or germinal centers. The majority of cluster B cells were IgD(+) with little evidence of class switch. Consistent with this, B cells isolated from the spinal cord were of the naïve/memory CD38(hi) CD95(lo) phenotype. Nevertheless, they were CD62L(lo) and CD80(hi) compared to lymph node B cells suggesting that they were at least partly activated and primed to present antigen. Therefore, if meningeal B cells contribute to CNS pathology in autoimmunity, follicular differentiation is not necessary for the pathogenic mechanism.

B cell recognition of myelin oligodendrocyte glycoprotein autoantigen depends on immunization with protein rather than short peptide, while B cell invasion of the CNS in autoimmunity does not.

We develop a new fusion protein reagent (MOGtag), based on the extracellular domain of mouse myelin oligodendrocyte glycoprotein (MOG1-125), designed to induce autoimmune responses in mice that incorporates both T and B cell recognition of antigen. Reports of similar reagents, primarily based on foreign MOG proteins, rely largely on disease incidence and severity, with little analysis of the underlying immune response or pathology. We characterize the immune response and central nervous system autoimmune disease elicited by MOGtag in mice and find that it results in the formation of a T cell-dependent germinal center B cell response. Unlike immunization with the short MOG35-55 peptide, this response incorporated B cells able to recognize MOG protein. The autoimmune disease resulting from immunization with MOGtag was chronic with clear evidence of an ongoing immune response and active white and gray matter infiltration by T cells as well as formation of B cell clusters in the meninges. Interestingly, development of B cell clusters was not absolutely dependent on the ability of B cells to recognize MOG protein, as they were also present in mice immunized with short peptide and in mice with a mutant B cell receptor specific for an irrelevant antigen.

Pathogenic fungus Batrachochytrium dendrobatidis in marbled water frog Telmatobius marmoratus: first record from Lake Titicaca, Bolivia.

The pathogenic fungus Batrachochytrium dendrobatidis (Bd) has been associated with amphibian declines worldwide but has not been well-studied among Critically Endangered amphibian species in Bolivia. We sampled free-living marbled water frogs Telmatobius marmoratus (Anura: Leptodactylidae) from Isla del Sol, Bolivia, for Bd using skin swabs and quantitative polymerase chain reactions. We detected Bd on 44% of T. marmoratus sampled. This is the first record of Bd in amphibians from waters associated with Lake Titicaca, Bolivia. These results further confirm the presence of Bd in Bolivia and substantiate the potential threat of this pathogen to the Critically Endangered, sympatric Titicaca water frog T. culeus and other Andean amphibians.

Nonadherence to prophylactic - negative attitudes toward doctors a strong predictor.

BACKGROUND: This study investigated factors that predict adherence to prophylactic medication. The design was data driven and aimed to expose the most prominent predictors of adherence. METHODS: A cross sectional sample of 24 males and 41 females, aged between 19 and 76 years, completed demographic questions, Medication Adherence Report Scale, Multidimensional Health Locus of Control Scale, Attitude towards Doctors and Medicine Scale, Eysenck Personality Questionnaire Revised (short scale) and the Short Form 36 Health Survey. RESULTS: Negative attitudes toward doctors, low mental health and chance health locus of control explained 33.2% of the variance in self reported medication nonadherence. DISCUSSION: That negative attitudes to doctors was a stronger predictor of nonadherence than side effects or medication cost was unexpected. Many studies have reported side effects and cost as primary reasons; however, these studies often do not assess the patient-doctor relationship.

'Too scary to think about': first time mothers' perceptions of the usefulness of antenatal breastfeeding education.

BACKGROUND: The purpose of this pilot study was to uncover the perceived usefulness of a contemporary antenatal education strategy for mother's experience of breastfeeding initiation. RESEARCH QUESTION: How useful do first time mothers perceive an antenatal education strategy to be for initiating breastfeeding? PARTICIPANTS AND METHODS: This was a simple descriptive pilot study with ten first time mothers as participants; all of whom were booked into an Australian private maternity unit for antenatal breastfeeding education, labour, birth and postpartum care. Semi-structured interviews were transcribed verbatim and thematically analysed. FINDINGS AND DISCUSSION: Antenatal education was beneficial for informing first time mothers of the practical skills required to positively initiate breastfeeding. However, this antenatal education strategy was not enough to reduce anxiety and foster the participants sense of self-confidence in their ability to breastfeed their newborns. IMPLICATIONS FOR PRACTICE: Recommendations are made to focus antenatal breastfeeding strategies on first, a strength based model that builds confidence in women's ability to successfully breastfeed. Second, in the interests of fully informed consent, women are to be advised about the physiological connection between pregnancy, labour, birth and breastfeeding and the impact that interventions such as synthetic oxytocin, caesarean section and epidural anaesthesia are likely to have on the initiation of breastfeeding.