Emergency department presentations with suicide and self-harm ideation: a missed opportunity for intervention?

AIMS: Suicidal ideation constitutes a central element of most theories of suicide and is the defining facet separating suicide from other causes of death such as accidents. However, despite a high worldwide prevalence, most research has focused on suicidal behaviours, such as completed suicide and suicide attempts, while the greater proportion who experienced ideation, which frequently precedes suicidal behaviour, have received much less attention. This study aims to examine the characteristics of those presenting to EDs with suicidal ideation and quantify the associated risk of suicide and other causes of death. METHODS: Retrospective cohort study was performed based on population-wide health administration data linked to data from the Northern Ireland Registry of Self-Harm and centrally held mortality records from April 2012 to December 2019. Mortality data, coded as suicide, all-external causes and all-cause mortality were analysed using Cox proportional hazards. Additional cause-specific analyses included accidental deaths, deaths from natural causes and drug and alcohol-related causes. RESULTS: There were 1,662,118 individuals aged over 10 years, of whom 15,267 presented to the ED with ideation during the study period. Individuals with ideation had a 10-fold increased risk of death from suicide (hazard ratio [HRadj] = 10.84, 95% confidence interval [CI] 9.18, 12.80) and from all-external causes (HRadj = 10.65, 95% CI 9.66, 11.74) and a threefold risk of death from all-causes (HRadj = 3.01, 95% CI 2.84, 3.20). Further cause-specific analyses indicated that risk of accidental death (HRadj = 8.24, 95% CI 6.29, 10.81), drug-related (HRadj = 15.17, 95% CI 11.36, 20.26) and alcohol-related (HRadj = 10.57, 95% CI 9.07, 12.31) has also significantly increased. There were few socio-demographic and economic characteristics that would identify which of these patients are most at risk of suicide or other causes of death. CONCLUSIONS: Identifying people with suicidal ideation is recognized to be both important but difficult in practice; this study shows that presentations to EDs with self-harm or suicide ideation represent an important potential intervention point for this hard-to-reach vulnerable population. However, and unlike individuals presenting with self-harm, clinical guidelines for the management and recommended best practice and care of these individuals are lacking. Whilst suicide prevention may be the primary focus of interventions aimed at those experiencing self-harm and suicide ideation, death from other preventable causes, especially substance misuse, should also be a cause of concern.

Risk of repetition and subsequent self-harm following presentation to hospital with suicidal ideation: A longitudinal registry study.

BACKGROUND: Few studies have focused on those who present to hospital with suicidal thoughts (suicidal ideation). The aim of this study was to establish the risk of repeat presentation to hospital following suicidal ideation and to identify factors which were associated with further ideation or subsequent self-harm. METHODS: Data were obtained from the Northern Ireland Registry of Self-harm. Risk of repeat presentation following hospital-presenting ideation was analysed using Kaplan Meier analyses, specifically cox proportional hazard models. FINDINGS: During the period April 2014 to March 2019, a total of 14,695 presentations to hospital due to suicidal ideation were made in Northern Ireland. The cumulative incidence of repeat presentation to hospital was 40·5% within five years, with an 18·3% risk of subsequent self-harm. Previous ideation had the strongest association with repeat presentation. There was evidence of recidivism considering further ideation, with an increased risk according to number of previous presentations. In contrast, risk of subsequent self-harm was highest after the first or second presentation. Male gender and alcohol were associated with further ideation, while females and young people were more likely to re-present with self-harm. INTERPRETATION: The findings indicate that individuals who present to hospital with suicidal ideation are at risk of repeat presentation and future self-harm, however clinical guidelines do not specifically address hospital-presenting ideation. The transition from ideation to suicidal behaviour is important to consider and research could inform effective screening and early intervention measures. ROLE OF FUNDING: The Northern Ireland Registry of Self-harm is funded by the Public Health Agency, Northern Ireland.

A two-step fluorinase enzyme mediated (18)F labelling of an RGD peptide for positron emission tomography.

A two-step radiolabelling protocol of a cancer relevant cRGD peptide is described where the fluorinase enzyme is used to catalyse a transhalogenation reaction to generate [(18)F]-5'-fluoro-5'-deoxy-2-ethynyladenosine, [(18)F]FDEA, followed by a 'click' reaction to an azide tethered cRGD peptide. This protocol offers efficient radiolabelling of a biologically relevant peptide construct in water at pH 7.8, 37 °C in 2 hours, which was metabolically stable in rats and retained high affinity for αVß3 integrin.

Conjugation of a TLR7 agonist and antigen enhances protection in the S. pneumoniae murine infection model.

Next generation vaccine adjuvants include Toll like receptor agonists, which are mostly extracted from microorganisms, but synthetic small molecule TLR agonists have also been identified. However, their delivery systems have not been optimized for effective administration in conjunction with antigens. Here, we describe a novel approach in which a small molecule TLR agonist was directly conjugated to antigen to ensure effective co-delivery. We describe the conjugation of a recombinant protective antigen from Streptococcus pneumoniae linked to a TLR7 agonist. Following thorough characterization to ensure no aggregation, the conjugate was evaluated in a murine infection model. Results showed that the conjugate extended the animals' survival after lethal challenge with S. pneumoniae. Comparable results were obtained with a dose 10-fold lower than that of the native unconjugated antigen. Notably, the animals immunized with the same dose of unconjugated TLR7 agonist and antigen showed no adjuvant effect. The increased immunogenicity was likely a consequence of the co-localization of TLR7 agonist and antigen by chemical binding and was more effective than simple co-administration. This approach can be adopted to increase potency of a broad variety of antigens and reduce the dose of antigen required to induce protective immunity.

Influenza subunit vaccine coated microneedle patches elicit comparable immune responses to intramuscular injection in guinea pigs.

Delivery of influenza vaccine using innovative approaches such as microneedles has been researched extensively in the past decade. In this study we present concentration followed by formulation and coating of monobulks from 2008/2009 seasonal vaccine on to 3M's solid microstructured transdermal system (sMTS) by a GMP-scalable process. The hemagglutinin (HA) in monobulks was concentrated by tangential flow filtration (TFF) to achieve HA concentrations as high as 20mg/ml. The stability of the coated antigens was evaluated by the functional assay, single radial immunodiffusion (SRID). The data generated show stability of the coated antigen upon storage at 4°C and room temperature in the presence of desiccant for at least 8 weeks. Freeze-thaw stability data indicate the stability of the coated antigen in stressed conditions. The vaccine coated microstructures were evaluated in vivo in a guinea pig model, and resulted in immune titers comparable to the traditional trivalent vaccine administered intramuscularly. The data presented indicate the potential use of the technology in delivery of influenza vaccine. This paper also addresses the key issues of stability of coated antigen, reproducibility and scalability of the processes used in preparation of influenza vaccine coated microneedle patches that are important in developing a successful product.

The mechanism of action of MF59 - an innately attractive adjuvant formulation.

MF59 is a safe and effective vaccine adjuvant which was originally approved to be included in a licensed influenza vaccine to be used in the elderly in Europe in 1997. The MF59 adjuvanted influenza vaccine (Fluad™) is now licensed in more than 20 countries worldwide and more than 85 million doses have been administered. More recently the vaccine adjuvant has also been shown to be safe and effective in young children and resulted in a significant increase in influenza vaccine efficacy in a controlled clinical trial in Europe. Since the early days of its discovery we have explored the mechanism of action of MF59, using a variety of available techniques. In recent years we have explored more thoroughly the mechanism of action using new and more sophisticated techniques. It is remarkable how consistent the data has been, using a variety of different approaches both in several small animal models and also using human immune cells in vitro. Here we present a summary of all the work performed to date on the mechanism of action of MF59 and we present a unified theory based on the accumulated data of how it exerts its adjuvant effects. A key element of the mechanism of action appears to be the creation of a transient 'immunocompetent' local environment at the injection site, resulting in the recruitment of key immune cells, which are able to take up antigen and adjuvant and transport them to the local lymph nodes, where the immune response is induced. This recruitment appears to be triggered by the induction of a chemokine driven gradient by the impact of MF59 on local cells, which are activated to secrete further chemokines, which are recruitment factors for more immune cells.

Driving forces underlying the formation of chiral domains of fluorinated diacids on graphite.

The role of intermolecular interactions, molecule-substrate interactions, and molecular chirality in the construction of 2-D surface architectures is the subject of much current interest. A racemic mixture of long chain hydrocarbons was synthesized with terminal carboxylic acid functionalities at each end and two amide linkages in the central region of the molecule on either side of two F-containing chiral centers. Using scanning tunnelling microscopy (STM), we have examined how the functionality of these molecules influences their self-assembly on a highly oriented pyrolytic graphite (HOPG) surface. The key factors determining the nature of ordered domains have been identified.

Molecular and cellular signatures of human vaccine adjuvants.

Oil-in-water emulsions are potent human adjuvants used for effective pandemic influenza vaccines; however, their mechanism of action is still unknown. By combining microarray and immunofluorescence analysis, we monitored the effects of the adjuvants MF59 oil-in-water emulsion, CpG, and alum in the mouse muscle. MF59 induced a time-dependent change in the expression of 891 genes, whereas CpG and alum regulated 387 and 312 genes, respectively. All adjuvants modulated a common set of 168 genes and promoted antigen-presenting cell recruitment. MF59 was the stronger inducer of cytokines, cytokine receptors, adhesion molecules involved in leukocyte migration, and antigen-presentation genes. In addition, MF59 triggered a more rapid influx of CD11b+ blood cells compared with other adjuvants. The early biomarkers selected by microarray, JunB and Ptx3, were used to identify skeletal muscle as a direct target of MF59. We propose that oil-in-water emulsions are the most efficient human vaccine adjuvants, because they induce an early and strong immunocompetent environment at the injection site by targeting muscle cells.

MF59 is a safe and potent vaccine adjuvant for flu vaccines in humans: what did we learn during its development?

The MF59 adjuvant has been included in a licensed influenza vaccine for a decade. Hence, we have a significant amount of clinical data to establish its potency and safety. We can now reassess our early preclinical studies and determine whether or not they were useful to predict human responses. The main lesson learned is that mouse models can be valuable, but one must ask the right questions and the models must be used appropriately.

Delivery systems and adjuvants for oral vaccines.

The oral route is the ideal means of delivering prophylactic and therapeutic vaccines, offering significant advantages over systemic delivery. Most notably, oral delivery is associated with simple administration and improved safety. In addition, unlike systemic immunisation, oral delivery can induce mucosal immune responses. However, the oral route of vaccine delivery is the most difficult because of the numerous barriers posed by the gastrointestinal tract. To facilitate effective immunisation with peptide and protein vaccines, antigens must be protected, uptake enhanced and the innate immune response activated. Numerous delivery systems and adjuvants have been evaluated for oral vaccine delivery, including live vectors, inert particles and bacterial toxins. Although developments in oral vaccines have been disappointing so far, in terms of the generation of products, the availability of a range of novel delivery systems offers much greater hope for the future development of improved oral vaccines.

Immunological implications of the use of plant lectins for drug and vaccine targeting to the gastrointestinal tract.

Plant lectins are under consideration as targeting agents to enhance the efficacy of orally administered drugs and vaccines. A significant issue that must be considered is the immunogenicity of these molecules since an immune response to the targeting agent may interfere with its ability to interact with the epithelium. In contrast, the ability of certain lectins to activate the immune system may be exploited in the delivery of vaccines. We previously demonstrated that plant lectins vary widely in their immunogenicity and in particular that mistletoe lectins (ML) I, II and II (MLI, MLII, MLIII) are potent immunogens when administered nasotracheally. Here, we measured immune responses following oral delivery of the MLs and assessed their ability to enhance responses to a co-administered antigen to determine if the molecules possess adjuvant activity. Oral administration of the lectins induced potent lectin-specific systemic and mucosal antibody responses. In addition, each of the three lectins possessed adjuvant activity when delivered orally together with ovalbumin (OVA). The lectins enhanced both serum and mucosal antibody responses to the co-delivered antigen. This shows for the first time that MLI, MLII and MLIII possess adjuvant activity when administered orally and may provide a platform for the generation of effective mucosal adjuvants.

Mistletoe lectins enhance immune responses to intranasally co-administered herpes simplex virus glycoprotein D2.

The mucosal adjuvant properties of the three type 2 ribosome-inactivating proteins (RIPs) from the European mistletoe, Viscum album L., were investigated. Mistletoe lectins were compared with cholera toxin (CT) as adjuvants when delivered nasotracheally together with herpes simplex virus glycoprotein D2 (gD2). All three mistletoe lectins (MLI, MLII, MLIII) were potent mucosal adjuvants. Co-administration of MLI, MLII or MLIII with gD2 led to significantly higher levels of gD2-specific mucosal immunoglobulin A (IgA) and systemic immunoglobulin G (IgG) antibody than when the antigen was delivered alone. The levels of antibodies induced were similar to those generated in mice immunized with gD2 and the potent mucosal adjuvant CT. Administration of ML1 with gD2 enhanced the antigen-specific splenic T-cell proliferative response. Interleukin-5 (IL-5), but not interferon-gamma (IFN-gamma), was detected in supernatants from splenocytes stimulated in vitro with gD2. This indicates that MLI enhanced type 2 T-helper cell (Th2) responses to the bystander antigen, gD2. Analysis of the gD2- and lectin-specific IgG subclass titres in mice immunized with gD2 and MLI, MLII or MLIII revealed a high ratio of IgG1 : IgG2a, which is compatible with the selective induction of Th2-type immune responses.

Synergistic adjuvant activity of immunostimulatory DNA and oil/water emulsions for immunization with HIV p55 gag antigen.

A synthetic oligonucleotide containing a previously identified adjuvant active CpG DNA sequence was evaluated for its ability to augment antibody and CTL responses to p55 gag from HIV-1 in mice. Surprisingly, the CpG oligonucleotide, although, it had previously been described as the most potent adjuvant sequence in mice for the particulate HbsAg, was ineffective when used in a simple combination with urea-solubilized p55 antigen. However, a potent adjuvant effect was observed with the CpG sequence when it was formulated with emulsions. Enhancement of antibody titer by CpG emulsion formulations was observed with urea-solubilized p55 antigen, however, significantly higher titers were obtained with p55 bound to polylactide-co-glycolide microparticles. In both cases IgG2a was enhanced in the presence of CpG. It appears likely that presentation of CpG with emulsions and particulate antigens enhances their delivery into antigen presenting cells (APC) and results in more effective presentation of antigen and adjuvant. To support this hypothesis, preliminary in vitro studies were undertaken to show upregulation of CD86 on mouse bone marrow-derived dendritic cells (BMDC) in vitro, following incubation with CpG formulations.

Human immunodeficiency virus type 1 Gag-specific vaginal immunity and protection after local immunizations with sindbis virus-based replicon particles.

The majority of human immunodeficiency virus (HIV) infections occur through vaginal and rectal transmission. In seeking a safe, nonreplicating gene-delivery vector that can induce mucosal and systemic immune responses and protection, Sindbis virus-based replicon particles expressing HIV-1 Gag (SIN-Gag) were developed. In mice, after nasal or intramuscular immunization with SIN-Gag and vaginal challenge with vaccinia virus (VV) expressing HIV-1 Gag (VV-Gag), CD8(+) T cell-mediated responses were detected locally, in the vaginal mucosa and in the draining iliac lymph nodes (ILNs), and systemically, in the spleen. However, the mice were not protected against VV-Gag replication in the ovaries. In contrast, after vaginal or rectal immunization with SIN-Gag and vaginal challenge with VV-Gag, despite lower local CD8(+) T cell-mediated responses in the vaginal mucosa and ILNs, the mice were protected against VV-Gag replication in the ovaries. Therefore, local immunization with SIN-Gag induced both local mucosal cell-mediated responses and protection.

Mucosal immunization with HIV-1 gag DNA on cationic microparticles prolongs gene expression and enhances local and systemic immunity.

There is an urgent need to develop vaccines against transmission of HIV through the vaginal and rectal mucosa. In the present study we tested the ability of DNA encoding HIV-1 gag adsorbed onto the surface of cationic polylactide co-glycolide microparticles (PLG-DNA) to induce local and systemic gag-specific immunity following mucosal delivery. We found gag-specific cell- and antibody-mediated responses in local as well as systemic lymphoid tissues following intranasal (IN) immunizations with PLG-DNA but not with naked DNA. IN immunizations with PLG-DNA, but not naked DNA, induced prolonged expression of gag protein in local and systemic lymphoid tissues. These data have important implications for DNA vaccine development.

Induction of potent immune responses by cationic microparticles with adsorbed human immunodeficiency virus DNA vaccines.

The effectiveness of cationic microparticles with adsorbed DNA at inducing immune responses was investigated in mice, guinea pigs, and rhesus macaques. Plasmid DNA vaccines encoding human immunodeficiency virus (HIV) Gag and Env adsorbed onto the surface of cationic poly(lactide-coglycolide) (PLG) microparticles were shown to be substantially more potent than corresponding naked DNA vaccines. In mice immunized with HIV gag DNA, adsorption onto PLG increased CD8(+) T-cell and antibody responses by approximately 100- and approximately 1,000-fold, respectively. In guinea pigs immunized with HIV env DNA adsorbed onto PLG, antibody responses showed a more rapid onset and achieved markedly higher enzyme-linked immunosorbent assay and neutralizing titers than in animals immunized with naked DNA. Further enhancement of antibody responses was observed in animals vaccinated with PLG/DNA microparticles formulated with aluminum phosphate. The magnitude of anti-Env antibody responses induced by PLG/DNA particles was equivalent to that induced by recombinant gp120 protein formulated with a strong adjuvant, MF-59. In guinea pigs immunized with a combination vaccine containing HIV env and HIV gag DNA plasmids on PLG microparticles, substantially superior antibody responses were induced against both components, as measured by onset, duration, and titer. Furthermore, PLG formulation overcame an apparent hyporesponsiveness of the env DNA component in the combination vaccine. Finally, preliminary data in rhesus macaques demonstrated a substantial enhancement of immune responses afforded by PLG/DNA. Therefore, formulation of DNA vaccines by adsorption onto PLG microparticles is a powerful means of increasing vaccine potency.

Recent developments in adjuvants for vaccines against infectious diseases.

New generation vaccines, particularly those based on recombinant proteins and DNA, are likely to be less reactogenic than traditional vaccines, but are also less immunogenic. Therefore, there is an urgent need for the development of new and improved vaccine adjuvants. Adjuvants can be broadly separated into two classes, based on their principal mechanisms of action; vaccine delivery systems and 'immunostimulatory adjuvants'. Vaccine delivery systems are generally particulate e.g. emulsions, microparticles, iscoms and liposomes, and mainly function to target associated antigens into antigen presenting cells (APC). In contrast, immunostimulatory adjuvants are predominantly derived from pathogens and often represent pathogen associated molecular patterns (PAMP) e.g. LPS, MPL, CpG DNA, which activate cells of the innate immune system. Once activated, cells of innate immunity drive and focus the acquired immune response. In some studies, delivery systems and immunostimulatory agents have been combined to prepare adjuvant delivery systems, which are designed for more effective delivery of the immunostimulatory adjuvant into APC. Recent progress in innate immunity is beginning to yield insight into the initiation of immune responses and the ways in which immunostimulatory adjuvants may enhance this process. However, a rational approach to the development of new and more effective vaccine adjuvants will require much further work to better define the mechanisms of action of existing adjuvants. The discovery of more potent adjuvants may allow the development of vaccines against infectious agents such as HIV which do not naturally elicit protective immunity. New adjuvants may also allow vaccines to be delivered mucosally.