Bacterial membrane vesicles deliver peptidoglycan to NOD1 in epithelial cells

Gram-negative bacterial peptidoglycan is specifically recognized by the host intracellular sensor NOD1, resulting in the generation of innate immune responses. Although epithelial cells are normally refractory to external stimulation with peptidoglycan, these cells have been shown to respond in a NOD1-dependent manner to Gram-negative pathogens that can either invade or secrete factors into host cells. In the present work, we report that Gram-negative bacteria can deliver peptidoglycan to cytosolic NOD1 in host cells via a novel mechanism involving outer membrane vesicles (OMVs). We purified OMVs from the Gram-negative mucosal pathogens: Helicobacter pylori, Pseudomonas aeruginosa and Neisseria gonorrhoea and demonstrated that these peptidoglycan containing OMVs upregulated NF-κB and NOD1-dependent responses in vitro. These OMVs entered epithelial cells through lipid rafts thereby inducing NOD1-dependent responses in vitro. Moreover, OMVs delivered intragastrically to mice-induced innate and adaptive immune responses via a NOD1-dependent but TLR-independent mechanism. Collectively, our findings identify OMVs as a generalized mechanism whereby Gram-negative bacteria deliver peptidoglycan to cytosolic NOD1. We propose that OMVs released by bacteria in vivo may promote inflammation and pathology in infected hosts.

Lipid membrane : a novel target for viral and bacterial pathogens

Abstracts: Lipid rafts are defined as specialized, dynamic microdomains that can be found in plasma membrane, and they are enriched with cholesterol and sphingolipids. Since lipid rafts’ first debut in the mid 1990’s, their existence, function and biological relevance have been a subject of intense scrutiny within the scientific community. Throughout this debate, we have learned a great deal regarding how cargos (both pathogens and cellular factors) are transported into and out of the cell through raft-dependent or raft-independent pathways. It is now apparent that a number of toxins, bacterial-, and viral-pathogens are able to exploit cholesterol and/or lipid rafts to gain a foot hold in their target hosts. The objective of this review is to describe our current appreciation on how selected pathogens utilise cholesterol and/or lipid rafts to support their propagation and to speculate on how some of these observations can be explored for the development of novel strategies that target plasma membrane lipids to control the spread of these viral- and bacterial-pathogens.

The relationship between attachment style, anxiety sensitivity and interpretive bias among adolescent nonclinical panickers

Elevated anxiety sensitivity and the tendency to catastrophically misinterpret ambiguous bodily sensations has been demonstrated in people who experience nonclinical levels of panic (Richards, Austin, & Alvarenga, 2001), and anxiety sensitivity has been shown to be associated with insecure attachment in adolescents and young adults (Weems, Berman, Silverman, and Saavedra, 2001). This study investigated the relationship between attachment style, anxiety sensitivity and catastrophic misinterpretation among 11 nonclinical panickers and 58 nonanxious controls aged 18 to 19 years. Participants completed the Brief Bodily Sensations Interpretation Questionnaire (BBSIQ), Anxiety Sensitivity Index (ASI) and an attachment questionnaire. The hypothesis that insecurely attached individuals would demonstrate greater catastrophic misinterpretation and higher anxiety sensitivity than securely attached individuals was not supported; however, nonclinical panickers gave more anxiety-related interpretations of ambiguous internal stimuli than nonanxious controls. Results do not support the notion that attachment style is related to anxiety sensitivity or catastrophic misinterpretation (regardless of panic experience). Results do, however, support the notion that anxiety-related misinterpretation of ambiguous somatic sensations precedes the onset of panic disorder.

In depression, bacterial translocation may drive inflammatory responses, oxidative and nitrosative stress (O&NS) and autoimmune responses directed against O&NS- damaged neoepitopes

Objective: Depression is accompanied by activation of immuno-inflammatory and oxidative and nitrosative stress (IO&NS) pathways, and increased IgM/IgA responses to lipopolysaccharide (LPS) of gram-negative commensal bacteria. The latter suggests that bacterial translocation has caused IgM/IgA responses directed against LPS. Bacterial translocation may drive IO&NS responses.

Method: To examine the associations between IgM/IgA responses to LPS and IO&NS measurements, including plasma/serum interleukin-1 (IL-1), tumor necrosis factor (TNF)α, neopterin, lysozyme, oxidized LDL (oxLDL) antibodies, peroxides, and IgM (auto)immune responses against malondialdehyde (MDA), azelaic acid, phophatidyl inositol (Pi), NO-tryptophan and NO-tyrosine in depressed patients and controls.

Results: We found significant positive associations between IgM/IgA responses to LPS and oxLDL antibodies, IgM responses against MDA, azelaic acid, Pi, NO-tryptophan, and NO-tyrosine. The IgA responses to LPS were correlated with lysozyme. There were no significant positive correlations between the IgM/IgA responses to LPS and IL-1 and neopterin.

Conclusion: The findings show that in depression there is an association between increased bacterial translocation and lysozyme production, an antibacterial compound, O&NS processes, and autoimmune responses directed against O&NS generated neoantigenic determinants. It is suggested that bacterial translocation may drive IO&NS pathways in depression and thus play a role in its pathophysiology.

Bacterial biosensors for measuring availability of environmental pollutants

Biosensors are projected to find many applications due to their high selectivity and sensitivity, rapid reaction, economy and ease of handling in field measurements. Even though biosensors for a wide range of environmental pollutants have been extensively reported in the literature, the decision to develop a suitable biosensing system that can be approved by a regulatory perspective for environmental applications is fraught with technical issues. These issues mainly concern the biological recognition element, the physico-chemical transducer and the interfaces between the biological and the physical components, but also aspects of fluidics, electronics, and software for data processing. This article focused on the development of microbial-based biosensors for environmental applications especially metal contaminants such as arsenic.

Adult attachment insecurities are related to obsessive compulsive phenomena

Obsessive-compulsive disorder (OCD) is one of the most disabling and highly prevalent anxiety disorders. Cognitive models implicate maladaptive beliefs such as inflated sense of responsibility, perfectionism, importance/control of thoughts in the maintenance of the disorder, but little research has investigated factors that may lead to these beliefs. This paper investigated whether a dysfunctional attachment system may be one such factor, by examining how adult attachment orientations (dimensions of attachment anxiety and avoidance) relate to OCDrelated cognitions, OCD symptoms, and depression. Using structural equation modeling in a student sample (N = 446), the present study found evidence for a mediational model, where attachment dimensions contributed to OCD symptoms via OCD-related cognitions, while controlling for depression. The paper discusses the association between adult attachment orientations and OCD symptoms in the context of current cognitive-behavioral theories of OCD.

Adult attachment insecurities are associated with obsessive compulsive disorder

Objectives.  Obsessive compulsive disorder (OCD) is one of the most disabling and highly prevalent anxiety disorders (ADs). Current cognitive models of OCD implicate views about the self and world in the maintenance of the disorder. However, little research has focused on issues that may lead to vulnerability to such views. In particular, a person's attachment insecurities (attachment anxiety, avoidance) may be important risk factors increasing the likelihood of such non-adaptive perceptions (Doron & Kyrios, 2005).

Design.  Participants meeting criteria for OCD were compared with cohorts meeting criteria for other ADs and healthy controls on a range of measures including adult attachment, OC symptoms, cognitions, and mood.

Methods.  Diagnosis of the clinical groups was established using the Anxiety Disorders Interview Schedule for DSM-IV (Brown, Di Nardo, & Barlow, 1994). The clinical relevance of attachment insecurities was ascertained by comparing their prevalence in an OCD sample (N= 30), an ADs sample (N= 20), and a community sample (N= 32). Results.  Attachment anxiety was significantly higher in individuals with OCD, even when controlling for depression.

Conclusions.  Addressing attachment anxiety in individuals presenting with OCD may be important for enhancing therapeutic outcomes. However, findings are based on cross-sectional data that preclude conclusions relating to causal influence.

Investigating the association between attachment and binge eating

A model was developed revealing direct and indirect effects of attachment anxiety and avoidance on various coping, regulatory, and affective factors that lead to the development and maintenance of binge eating. Insecurely attached individuals demonstrated more use of food as a source of comfort and security than their insecure counterparts.

A multi-level investigation of leadership from an attachment theory perspective

This thesis investigated the nature of interpersonal relationships between leaders and followers in the workplace. Results indicated that the relationship styles of leaders and followers were associated with differential ratings of leadership across varying workplace contexts.