Prostaglandin E2 synthases in neurologic homeostasis and disease

Prostaglandin E₂ synthases (PGES) currently comprise a group of three structurally and biologically distinct molecules. These enzymes are part of an important and complex paracrine signaling system involved in a wide range of biological processes. This review focuses on the normal physiological and pathological roles of these enzymes in the nervous system. Specific topics include the role of PGES(s) in fever and sickness behavior, inflammatory pain, and neural disease. Although the field is in its early stages, ongoing development of selective PGES inhibitors for possible use in people creates a significant need for more fully understanding the biological roles of these important enzymes.     

SHP-1- and phosphotyrosine-independent inhibitory signaling by a killer cell Ig-like receptor cytoplasmic domain in human NK cells

Killer cell Ig-like receptors (KIR) are MHC class I-binding immunoreceptors that can suppress activation of human NK cells through recruitment of the Src homology 2-containing protein tyrosine phosphatase-1 (SHP-1) to two immunoreceptor tyrosine-based inhibitory motifs (ITIMs) in their cytoplasmic domains. KIR2DL4 (2DL4; CD158d) is a structurally distinct member of the KIR family, which is expressed on most, if not all, human NK cells. 2DL4 contains only one ITIM in its cytoplasmic domain and an arginine in its transmembrane region, suggesting both inhibitory and activating functions. While 2DL4 can activate IFN-gamma production, dependent upon the transmembrane arginine, the function of the single ITIM of 2DL4 remains unknown. In this study, tandem ITIMs of KIR3DL1 (3DL1) and the single ITIM of 2DL4 were directly compared in functional and biochemical assays. Using a retroviral transduction method, we show in human NK cell lines that 1) the single ITIM of 2DL4 efficiently inhibits natural cytotoxicity responses; 2) the phosphorylated single ITIM recruits SHP-2 protein tyrosine phosphatase, but not SHP-1 in NK cells; 3) expression of dominant-negative SHP-1 does not block the ability of 2DL4 to inhibit natural cytotoxicity; 4) surprisingly, mutation of the tyrosine within the single ITIM does not completely abolish inhibitory function; and 5) this correlates with weak SHP-2 binding to the mutant ITIM of 2DL4 in NK cells and a corresponding nonphosphorylated ITIM peptide in vitro. These results reveal new aspects of the KIR-inhibitory pathway in human NK cells, which are SHP-1 and phosphotyrosine independent.     

Aneurysm severity is suppressed by deletion of CCN4

Patients with abdominal aortic aneurysms are frequently treated with high-risk surgery. A pharmaceutical treatment to reverse aneurysm progression could prevent the need for surgery and save both lives and healthcare resources. Since CCN4 regulates cell migration, proliferation and apoptosis, processes involved in aneurysm progression, it is a potential regulator of aneurysm progression. We investigated the role of CCN4 in a mouse aneurysm model, using apolipoprotein-E knockout (ApoE^−/−) mice fed high fat diet and infused with Angiotensin II (AngII). Blood pressure was similarly elevated in CCN4^−/−ApoE^−/− mice and CCN4^+/+ApoE^−/− mice (controls) in response to AngII infusion. Deletion of CCN4 significantly reduced the number of ruptured aortae, both thoracic and abdominal aortic area, and aneurysm grade score, compared to controls. Additionally, the frequency of vessel wall remodelling and the number of elastic lamina breaks was significantly suppressed in CCN4^−/−ApoE^−/− mice compared to controls. Immunohistochemistry revealed a significantly lower proportion of macrophages, while the proportion of smooth muscle cells was not affected by the deletion of CCN4. There was also a reduction in both proliferation and apoptosis in CCN4^−/−ApoE^−/− mice compared to controls. In vitro studies showed that CCN4 significantly increased monocyte adhesion beyond that seen with TNFα and stimulated macrophage migration by more than threefold. In summary, absence of CCN4 reduced aneurysm severity and improved aortic integrity, which may be the result of reduced macrophage infiltration and cell apoptosis. Inhibition of CCN4 could offer a potential therapeutic approach for the treatment of aneurysms.Supplementary InformationThe online version contains supplementary material available at 10.1007/s12079-021-00623-5.     

Mobile elements create strain-level variation in the services conferred by an aphid symbiont

Heritable, facultative symbionts are common in arthropods, often functioning in host defence. Despite moderately reduced genomes, facultative symbionts retain evolutionary potential through mobile genetic elements (MGEs). MGEs form the primary basis of strain-level variation in genome content and architecture, and often correlate with variability in symbiont-mediated phenotypes. In pea aphids (Acyrthosiphon pisum), strain-level variation in the type of toxin-encoding bacteriophages (APSEs) carried by the bacterium Hamiltonella defensa correlates with strength of defence against parasitoids. However, co-inheritance creates difficulties for partitioning their relative contributions to aphid defence. Here we identified isolates of H. defensa that were nearly identical except for APSE type. When holding H. defensa genotype constant, protection levels corresponded to APSE virulence module type. Results further indicated that APSEs move repeatedly within some H. defensa clades providing a mechanism for rapid evolution in anti-parasitoid defences. Strain variation in H. defensa also correlates with the presence of a second symbiont Fukatsuia symbiotica. Predictions that nutritional interactions structured this coinfection were not supported by comparative genomics, but bacteriocin-containing plasmids unique to co-infecting strains may contribute to their common pairing. In conclusion, strain diversity, and joint capacities for horizontal transfer of MGEs and symbionts, are emergent players in the rapid evolution of arthropods.     

Isolation of a native osteoblast matrix with a specific affinity for BMP2

During their commitment and differentiation toward the osteoblast lineage, mesenchymal stem cells secrete a unique extracellular matrix (ECM) that contains large quantities of glycosaminoglycans (GAGs). Proteoglycans (PGs) are major structural and functional components of the ECM and are composed of a core protein to which one or more glycosaminoglycan sugar chains (GAGs) attach. The association of BMP2, a member of the TGF-β super-family of growth factors, and a known heparin-binding protein, with GAGs has been implicated as playing a significant role in modulating the growth factor’s in vitro bioactivity. Here we have characterised an osteoblast-derived matrix (MX) obtained from decellularised MC3T3-E1 cell monolayers for its structural attributes, using SEM and histology, and for its functional ability to maintain cell growth and viability. Using a combination of histology and anion exchange chromatography, we first confirmed the retention of GAGs within MX following the decellularisation process. Then the binding specificity of the retained GAG species within the MX for BMP2 was examined using a BMP2-HBP/EGFP (BMP2 Heparin-Binding Peptide/Enhanced Green Fluorescent Protein) fusion protein. The results of this study provide further evidence for a central role of the ECM in the regulation of BMP2 bioactivity, hence on mesenchymal stem cell commitment to the osteoblast lineage.     

Travelling Waves of Attached and Detached Cells in a Wound-Healing Cell Migration Assay

During a wound-healing cell migration assay experiment, cells are observed to detach and undergo mitosis before reattaching as a pair of cells on the substrate. During experiments with mice 3T3 fibroblasts, cell detachment can be confined to the wavefront region or it can occur over the whole wave profile. A multi-species continuum approach to modelling a wound-healing assay is taken to account for this phenomenon. The first cell population is composed of attached motile cells, while the second population is composed of detached immotile cells undergoing mitosis and returning to the migrating population after successful division. The first model describes cell division occurring only in the wavefront region, while a second model describes cell division over the whole of the scrape wound. The first model reverts to the Fisher equation when the reattachment rate relative to the detachment rate is large, while the second case does not revert to the Fisher equation in any limit. The models yield travelling wave solutions. The minimum wave speed is slower than the minimum Fisher wave speed and its dependence on the cell detachment and reattachment rate parameters is analysed. Approximate travelling wave profiles of the two cell populations are determined asymptotically under certain parameter regimes.     

Clinical Characteristics and Outcomes in Patients with Pulmonary Blastomycosis

Background  Blastomycosis is an uncommon granulomatous infection caused by the thermally dimorphic fungus Blastomyces dermatitidis. The most frequent clinical infections involve the lung, skin, and bone. Pulmonary manifestations range from asymptomatic self-limited infection to severe diffuse pneumonia causing respiratory failure. Objectives  To establish the clinical characteristics and outcomes of patients with pulmonary blastomycosis diagnosed at hospitals in Manitoba and northwestern Ontario, Canada. Methods  A retrospective review of medical records was done for 318 patients with blastomycosis in these regions. Results  The majority of patients were Caucasian (198 (62.5%) patients), male (193 (61%) patients), and residents of Ontario (209 (65.7%) patients). Most patients were treated in an inpatient hospital ward (266 (84%) patients) and survived (294 (92%) patients). Pulmonary involvement, either alone or associated with other sites, was present in 296 (93%) of the 318 patients; 22 (7%) patients had no evidence of pulmonary blastomycosis. The majority of patients had localized lung disease (1–3 quadrants on chest radiograph involved; 225 (82%) patients). Of 294 (92%) patients requiring hospitalization, 266 (90%) patients received all inpatient care on a general medical ward; 28 (10%) patients received some care in the intensive care unit (ICU). Factors associated with ICU admission included diffuse pulmonary disease (four quadrants involved on chest radiograph), diabetes, and prior use of antimicrobial therapy. Twenty-four (8%) patients died, and multivariate analysis showed that older age and Aboriginal ethnicity were the significant risk factors for death from blastomycosis. Conclusion  Blastomycosis is a cause of serious, potentially life-threatening pulmonary infection in this geographic region. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

The visual assessment of broth cultures for tissue bank samples

The bioburden screening process of allograft musculoskeletal tissue samples received at the South Eastern Area Laboratory Services includes the routine use of solid agar and cooked meat (CM) broth media. CM has been routinely sub-cultured onto solid agar plates after aerobic incubation at 35 °C. This study will evaluate whether a visual assessment of CM can replace sub-culture by an in vitro inoculation and a prospective study. Eight challenge organisms were serially diluted and inoculated into CM. The average inoculum of 0.5–5.5 CFU produced visible turbidity of CM after 24-h incubation for 7 of the challenge organisms with one organism producing turbidity after 48-h incubation. The prospective study evaluated 222 CM of which 213 were visually clear and no-growth on sub-culture and 9 turbid CM which were culture positive. Broth cultures are an integral part of the bioburden screening process of allograft musculoskeletal tissue and swab samples and visual assessment of CM can replace sub-culture.