BET 2: Should real resuscitationists use airway checklists?

A short cut review was carried out to establish whether the use of preprocedural checklists prior to intubation of critically ill patients outside a theatre environment can reduce the incidence of adverse events. Four directly relevant papers were found using the reported search strategy and presented the best evidence to answer the clinical question. The author, date and country of publication, patient group studied, study type, relevant outcomes, results and study weaknesses of these papers are tabulated. It is concluded that preprocedural checklists may reduce adverse events in these patients, but that the evidence level is low and further matched cohort studies are needed to prove effectiveness.

Impaired T-cell responses to sphingosine-1-phosphate in HIV-1 infected lymph nodes.

The determinants of HIV-1-associated lymphadenopathy are poorly understood. We hypothesized that lymphocytes could be sequestered in the HIV-1+ lymph node (LN) through impairments in sphingosine-1-phosphate (S1P) responsiveness. To test this hypothesis, we developed novel assays for S1P-induced Akt phosphorylation and actin polymerization. In the HIV-1+ LN, naïve CD4 T cells and central memory CD4 and CD8 T cells had impaired Akt phosphorylation in response to S1P, whereas actin polymerization responses to S1P were impaired dramatically in all LN maturation subsets. These defects were improved with antiretroviral therapy. LN T cells expressing CD69 were unable to respond to S1P in either assay, yet impaired S1P responses were also seen in HIV-1+ LN T cells lacking CD69 expression. Microbial elements, HIV-1, and interferon α - putative drivers of HIV-1 associated immune activation all tended to increase CD69 expression and reduce T-cell responses to S1P in vitro. Impairment in T-cell egress from lymph nodes through decreased S1P responsiveness may contribute to HIV-1-associated LN enlargement and to immune dysregulation in a key organ of immune homeostasis.

Circulating CD4(+) and CD8(+) T cells are activated in inflammatory bowel disease and are associated with plasma markers of inflammation.

Inflammatory bowel disease (IBD) is characterized by damage to the gut mucosa and systemic inflammation. We sought to evaluate the role of chronic inflammation on circulating T-cell activation in human subjects with Crohn's disease and ulcerative colitis. We studied 54 patients with IBD and 28 healthy controls. T-cell activation and cycling were assessed in whole blood samples by flow cytometry. Levels of lipopolysaccharide (LPS) were measured in serum by Limulus amoebocyte lysate assay, and plasma levels of inflammatory markers and LPS-binding proteins were measured by ELISA. The proportions of circulating CD4(+) and CD8(+) T lymphocytes in cycle (Ki67(+) ) are increased in patients with IBD compared with these proportions in controls. CD8(+) T cells from patients with IBD are also enriched for cells that expressed CD38 and HLA-DR, and proportions of these cells are related to plasma levels of interleukin-6 and C-reactive protein in these patients. Intracellular interleukin-2 and interferon-γ levels were elevated in resting and polyclonally activated CD4(+) and CD8(+) T cells in patients with IBD when compared with levels from healthy controls. Surprisingly, we did not find increased levels of LPS in the serum of patients with IBD. We did, however, find a signature of recent microbial translocation, as levels of LPS-binding protein are increased in the plasma of patients with IBD compared with plasma levels in healthy controls; LPS-binding protein levels are also directly related to proportions of CD38 HLA-DR-expressing CD4(+) and CD8(+) T cells. Local damage to the gastrointestinal tract in IBD may result in systemic inflammation and T-cell activation.

Genetically associated CD16(+)56(-) natural killer cell interferon (IFN)-αR expression regulates signaling and is implicated in IFN-α-induced hepatitis C virus decline.

BACKGROUND: Natural killer (NK) cells likely contribute to outcome of acute hepatitis C virus (HCV) infection and interferon (IFN)-induced control of chronic HCV infection. We previously observed IFN-αR and NKp30 expression associated with IFN-α-dependent NK cell activity. METHODS: Here, we examined CD16(+)56(-), CD16(+)56(+), and CD16(-)56(+) NK cell subset IFN-αR and NKp30 expression in relation to magnitude of HCV genotype 1 decrease during pegylated IFN-α plus ribavirin therapy. RESULTS: We observed greater baseline IFN-αR and NKp30 expression on CD16(+)56(+) and CD16(-)56(+) NK subsets in HCV-infected patients than in healthy control subjects. Baseline CD16(+)56(-) NK IFN-αR expression was associated with IFN-α-induced pSTAT1, and both were associated with magnitude of HCV decrease during pegylated IFN-α plus ribavirin therapy. Baseline CD16(+)56(-) NK IFN-αR expression was associated with race and interleukin 28B genotype, negatively associated with aspartate aminotransferase-to platelet ratio index, and positively associated with increase in NKp30 expression after in vivo IFN-α exposure. Finally, in vitro IFN-α2a-activated NK cytolysis of HCV-infected target cells was in part dependent on NKp30, and CD16(+)56(-) NK cell IFN-αR expression correlated with cytolytic activity. CONCLUSIONS: IFN-αR expression on CD16(+)56(-) NK cells during chronic HCV infection may in part be genetically determined, and level of expression regulates IFN-α signaling, which in turn may contribute to control of HCV infection.

Accuracy of substance exposure history in patients attending emergency departments after substance misuse; a comparison with biological sample analysis.

CONTEXT: Acute toxicity caused by illicit substance use is a common reason for emergency department (ED) presentation. Knowledge of the substances involved is helpful for predicting and managing potential toxicity, but limited information is available about the accuracy of patient-reported substance exposure. This study assessed the accuracy of the history of exposure in those reporting use of a single substance by comparison with those identified by detailed toxicological analysis, focusing on synthetic cannabinoid receptor agonists (SCRA). METHODS: Adults (≥16 years) presenting between March 2015 and July 2021 to participating UK hospitals with toxicity after reporting use of a single illicit substance were included. Exposure details were documented from medical records and blood and/or urine samples analysed using high-resolution accurate mass liquid chromatography-mass spectrometry (HRAM LCMS). Sensitivity, specificity, and positive and negative predictive values of the exposure history were calculated by comparison with biological sample analysis ("gold standard"). RESULTS: Single substance exposure was reported for 474 (median age 33 years, IQR: 18 range 16-75, 80% males) patients. Analysis commonly identified multiple substances (Median 3, IQR 2-5). A history of exposure was documented for 121 of 151 patients where a SCRA or metabolite was detected on analysis (sensitivity 80.1%, 95% CI 72.9, 86.2%). Corresponding proportions were lower for 3,4-methylenedioxymethamphetamine (MDMA, 44/70, 62.9%., 95% CI 50.5%, 74.1%), heroin 41/108 (38.0% 95% CI 28.8-47.8%) and cocaine (22/56, 31.3%, 95% CI 20.9, 43.6%). CONCLUSIONS: Multiple undeclared substances were detected analytically in most patients reporting single substance use. Clinicians should be alert to the potential presence and toxicity of unreported substances when managing patients presenting after substance misuse.

CpG-B oligodeoxynucleotides inhibit TLR-dependent and -independent induction of type I IFN in dendritic cells.

CpG oligodeoxynucleotides (ODNs) signal through TLR9 to induce type I IFN (IFN-alphabeta) in dendritic cells (DCs). CpG-A ODNs are more efficacious than CpG-B ODNs for induction of IFN-alphabeta. Because IFN-alphabeta may contribute to autoimmunity, it is important to identify mechanisms to inhibit induction of IFN-alphabeta. In our studies, CpG-B ODN inhibited induction of IFN-alphabeta by CpG-A ODN, whereas induction of TNF-alpha and IL-12p40 by CpG-A ODN was not affected. CpG-B inhibition of IFN-alphabeta was observed in FLT3 ligand-induced murine DCs, purified murine myeloid DCs, plasmacytoid DCs, and human PBMCs. CpG-B ODN inhibited induction of IFN-alphabeta by agonists of multiple receptors, including MyD88-dependent TLRs (CpG-A ODN signaling via TLR9, or R837 or Sendai virus signaling via TLR7) and MyD88-independent receptors (polyinosinic:polycytidylic acid signaling via TLR3 or ds break-DNA signaling via a cytosolic pathway). CpG-B ODN did not inhibit the IFN-alphabeta positive feedback loop second-wave IFN-alphabeta, because IFN-alphabeta-induced expression of IFN-alphabeta was unaffected, and CpG-B inhibition of IFN-alphabeta was manifested in IFN-alphabetaR(-/-) DCs, which lack the positive feedback mechanism. Rather, CpG-B ODN inhibited early TLR-induced first wave IFN-alpha4 and IFN-beta. Chromatin immunoprecipitation revealed that association of IFN regulatory factor 1 with the IFN-alpha4 and IFN-beta promoters was induced by CpG-A ODN but not CpG-B ODN. Moreover, CpG-A-induced association of IFN regulatory factor 1 with these promoters was inhibited by CpG-B ODN. Our studies demonstrate a novel mechanism of transcriptional regulation of first-wave IFN-alphabeta that selectively inhibits induction of IFN-alphabeta downstream of multiple receptors and may provide targets for future therapeutic inhibition of IFN-alphabeta expression in vivo.

Desensitization to type I interferon in HIV-1 infection correlates with markers of immune activation and disease progression.

Type I interferon (IFNalpha/beta) plays a complex role in HIV-1 infection and has been proposed alternately to have roles in either disease protection or progression. Although IFNalpha/beta plays crucial roles in regulating monocytes and dendritic cells, responsiveness of these cells to IFNalpha/beta in HIV-1 infection is poorly understood. We report significant defects in IFNalpha/beta receptor (IFNalpha/betaR) expression, IFNalpha signaling, and IFNalpha-induced gene expression in monocytes from HIV-1-infected subjects. IFNalpha/betaR expression correlated directly with CD4+ T-cell count and inversely with HIV-1 RNA level and expression of CD38 by memory (CD45RO+) CD8+ T cells, a measure of pathologic immune activation in HIV-1 infection associated with disease progression. In addition, monocytes from HIV-1-infected persons showed diminished responses to IFNalpha, including decreased induction of phosphorylated STAT1 and the classical interferon-stimulated gene produces MxA and OAS. These IFNalpha responses were decreased regardless of IFNalpha/betaR expression, suggesting that regulation of intracellular signaling may contribute to unresponsiveness to IFNalpha/beta in HIV-1 disease. Defective monocyte responses to IFNalpha/beta may play an important role in the pathogenesis of HIV-1 infection, and decreased IFNalpha/betaR expression may serve as a novel marker of disease progression.

Rapid up-regulation and granule-independent transport of perforin to the immunological synapse define a novel mechanism of antigen-specific CD8+ T cell cytotoxic activity.

CTL are endowed with the ability to eliminate pathogens through perforin-mediated cytotoxic activity. The mechanism for perforin-mediated Ag-specific killing has been solely attributed to cytotoxic granule exocytosis from activated CD8(+) T cells. In this study, we redefine this mechanism, demonstrating that virus-specific CD8(+) T cells rapidly up-regulate perforin in response to stimulation temporally with IFN-gamma and CD107a expression. Following Ag-specific activation, newly synthesized perforin rapidly appears at the immunological synapse, both in association with and independent of cytotoxic granules, where it functions to promote cytotoxicity. Our work suggests a novel mechanism of CTL cytotoxicity and identifies a novel correlate of CD8(+) T cell-mediated immunity.

Determinants of protection among HIV­exposed seronegative persons: an overview.

Both clinical experience and a growing medical literature indicate that some persons who have been exposed to human immunodeficiency virus (HIV) infection remain uninfected. Although in some instances this may represent good fortune, cohorts of uninfected persons have been reported who are considered at high risk for infection. In these cohorts a variety of characteristics have been proposed as mediating protection, but to date only the 32–base pair deletion in the chemokine (C‐C motif) receptor 5 gene, which results in complete failure of cell surface expression of this coreceptor, has been associated with high‐level protection from HIV infection. With this in mind, there are probably many other factors that may individually or in combination provide some level of protection from acquisition of HIV infection. Because some of these factors are probably incompletely protective or inconsistently active, identifying them with confidence will be difficult. Nonetheless, clarifying the determinants of protection against HIV infection is a high priority that will require careful selection of high‐risk uninfected cohorts, who should undergo targeted studies of plausible mediators and broad screening for unexpected determinants of protection.

Programmed death ligand 1 protein expression, histological tumour differentiation and intratumoural heterogeneity in pulmonary adenocarcinoma.

Intratumoural heterogeneity of pulmonary adenocarcinoma challenges the accurate interpretation of programmed death ligand 1 (PD-L1) immunohistochemistry, which is the only validated predictive marker for successful anti-PD-1/PD-L1 immunotherapy. The aim of this study was to determine whether PD-L1 expression is related to adenocarcinoma histological differentiation in a retrospective analysis of tumour biopsies with intratumoural histological heterogeneity. Adenocarcinomas with high intratumoural heterogeneity were categorised as 'mixed adenocarcinomas'. PD-L1 expression was determined immunohistochemically using tumour proportion scores (TPS). In 'mixed adenocarcinomas' PD-L1 scores were assessed across tumour areas with specific histological patterns. Comparisons were performed between histologically distinct differentiated tumours and/or histological areas. Poorly differentiated adenocarcinomas, represented by predominantly solid or micropapillary histological patterns, showed significantly higher expression of PD-L1 than other subtypes (p<0.001). Differentiation of intra-adenocarcinoma components was inversely correlated with PD-L1 expression: there were more PD-L1 positive cells in poorly differentiated areas than less differentiated (p<0.001), or than well differentiated areas (p<0.001), and in less differentiated more than well differentiated areas (p=0.001). In conclusion, PD-L1 expression is associated with poorly differentiated morphology in adenocarcinomas with intratumoural histological heterogeneity. Consequently, a TPS approach may not account for the contribution of more aggressive tumour components with higher levels of PD-L1 expression in within the tumour. Performing spectral analyses of PD-L1 expression across tumours is likely to be more accurate.

Specificity of anti-human leukocyte antigen antibody responses after immunization with Remune, an inactivated HIV-1 vaccine.

Antibody responses against human leukocyte antigen (HLA) classes I and II were detected in HIV-1 infected individuals who received a fixed inactivated HIV-1 (Remune) immunotherapy. The response was specific for HLA-B62 and HLA-DR4 concordant with the host cell line, HUT-78, used in vaccine production. These responses were not detected in HLA-B62 and HLA-DR4-positive individuals indicating that immunotherapy did not break tolerance to self-antigens.

A phase I, randomized study of combined IL-2 and therapeutic immunisation with antiretroviral therapy.

BACKGROUND: Fully functional HIV-1-specific CD8 and CD4 effector T-cell responses are vital to the containment of viral activity and disease progression. These responses are lacking in HIV-1-infected patients with progressive disease. We attempted to augment fully functional HIV-1-specific CD8 and CD4 effector T-cell responses in patients with advanced chronic HIV-1 infection. DESIGN: Chronically infected patients with low CD4 counts T-cell counts who commenced antiretroviral therapy (ART) were subsequently treated with combined interleukin-2 and therapeutic vaccination. METHODS: Thirty six anti-retroviral naive patients were recruited and initiated on combination ART for 17 weeks before randomization to: A) ongoing ART alone; B) ART with IL-2 twice daily for 5 days every four weeks starting at week 17 for 3 cycles; C) ART with IL-2 as in group B and Remune HIV-1 vaccine administered once every 3 months, starting at week 17; and D) ART with Remune vaccine as in group C. Patients were studied for 65 weeks following commencement of ART, with an additional prior 6 week lead-in observation period. CD4 and CD8 T-cell counts, evaluations of HIV-1 RNA levels and proliferative responses to recall and HIV-1 antigens were complemented with assessment of IL-4-secretion alongside quantification of anti-HIV-1 CD8 T-cell responses and neutralizing antibody titres. RESULTS: Neither IL-2 nor Remune vaccination induced sustained HIV-1-specific T-cell responses. However, we report an inverse relationship between HIV-1-specific proliferative responses and IL-4 production which continuously increased in patients receiving immunotherapy, but not patients receiving ART alone. CONCLUSION: Induction of HIV-1-specific cell-mediated responses is a major challenge in chronically HIV-1-infected patients even when combining immunisation with IL-2 therapy. An antigen-specific IL-4-associated suppressive response may play a role in attenuating HIV-specific responses.

Immune Responses in the Central Nervous System Are Anatomically Segregated in a Non-Human Primate Model of Human Immunodeficiency Virus Infection.

The human immunodeficiency virus (HIV) accesses the central nervous system (CNS) early during infection, leading to HIV-associated cognitive impairment and establishment of a viral reservoir. Here, we describe a dichotomy in inflammatory responses in different CNS regions in simian immunodeficiency virus (SIV)-infected macaques, a model for HIV infection. We found increased expression of inflammatory genes and perivascular leukocyte infiltration in the midbrain of SIV-infected macaques. Conversely, the frontal lobe showed downregulation of inflammatory genes associated with interferon-γ and interleukin-6 pathways, and absence of perivascular cuffing. These immunologic alterations were not accompanied by differences in SIV transcriptional activity within the tissue. Altered expression of genes associated with neurotoxicity was observed in both midbrain and frontal lobe. The segregation of inflammatory responses to specific regions of the CNS may both account for HIV-associated neurological symptoms and constitute a critical hurdle for HIV eradication by shielding the CNS viral reservoir from antiviral immunity.

Interferon-α inhibits CD4 T cell responses to interleukin-7 and interleukin-2 and selectively interferes with Akt signaling.

Persistent type I IFN production occurs during chronic viral infections, such as HIV disease. As type I IFNs have antiproliferative activity, it is possible that chronic exposure to these cytokines could adversely affect T cell homeostasis. We investigated the capacity of IFN-α to impair T cell proliferation induced by the homeostatic cytokine, IL-7, or another common γ-chain cytokine, IL-2, in cells from healthy human donors. We found that IL-7- or IL-2-induced proliferation of CD4(+) T cells was partially inhibited in the presence of IFN-α. The CD4(+) T cells that were exposed to IFN-α also displayed attenuated induction of IL-2 and CD40L following TCR stimulation. Analyses of signaling pathways indicated that IL-7 and IL-2 induced a delayed and sustained P-Akt signal that lasted for several days and was partially inhibited by IFN-α. In contrast, IL-7-induced P-STAT5 was not affected by IFN-α. Furthermore, IFN-α had no detectable effect on P-Akt that was induced by the chemokine SDF-1. Both inhibitors of P-Akt and P-STAT5 blocked IL-7-induced T cell proliferation, confirming that both signaling pathways are important for IL-7-induced T cell proliferation. These results demonstrate that IFN-α can selectively inhibit cytokine-induced P-Akt as a potential mechanism to disrupt homeostasis of T lymphocytes.

Aviremia 10 Years Postdiscontinuation of Antiretroviral Therapy Initiated During Primary Human Immunodeficiency Virus-1 Infection and Association With Gag-Specific T-Cell Responses.

Combination antiretroviral therapy during primary human immunodeficiency virus-1 infection may enable long-term drug-free virological control in rare individuals. We describe a female who maintained aviremia and a normal CD4(+)/CD8(+) T cell ratio for 10 years after stopping therapy, despite a persistent viral reservoir. Cellular immune responses may have contributed to this outcome.

Interleukin-2-associated viral breakthroughs induce HIV-1-specific CD4 T cell responses in patients on fully suppressive highly active antiretroviral therapy.

The combination of intermittent subcutaneous IL-2 and highly active antiretroviral therapy in individuals infected with HIV-1 has been shown to have a beneficial quantitative effect on the CD4 T cell count. We observed IL-2-associated viral load 'blips' inducing HIV-1-specific lymphoproliferative responses at 24 weeks in such individuals. This immunotherapeutic approach, utilizing autologous virus as autovaccination, may be a viable, safer alternative to structured treatment interruption and potentially more efficacious than therapeutic vaccines.

Tetanus vaccination with IL-2 during highly active antiretroviral therapy induces sustained and pronounced specific CD4 T-cell responses.

HIV-1 infection results in profound dysfunction of the CD4 T-cell population. Although highly active antiretroviral therapy allows the reconstitution of CD4 T-cell numbers, functional abnormalities remain, including inadequate responses to vaccination. IL-2 increases CD4 T-cell numbers and function. We report the effects of IL-2 given with tetanus vaccination in two patients in a larger immunotherapy study. In one case IL-2 induced sustained responses, which may have been caused by the timing of IL-2 with vaccination.

The immune system: our best antiretroviral.

A better understanding of the potent immune responses elicited by HIV before infected patients become immunocompromised should enable therapeutic immunomodulation to prevent disease progression. We review the nature of the immune response in HIV infected long-term nonprogressor patients; how and why the immune system fails; and whether it may be feasible to harness the immune system to control viraemia and extend the asymptomatic period in HIV infected persons. Finally we discuss the possibility of inducing sterilizing immunity to enable the host to rid itself of the virus.

Thymic output during initial highly active antiretroviral therapy (HAART) and during HAART supplementation with interleukin 2 and/or with HIV type 1 immunogen (Remune).

The thymic output of patients receiving highly active antiretroviral therapy (HAART) was assessed by sjTREC (signal joint T cell receptor rearrangement excision circle) analysis to determine the thymic contribution to CD4(+) T cell reconstitution during initial therapy and during interleukin 2 (IL-2) and/or Remune supplementation of HAART. Levels of sjTRECs were observed to decline dramatically after the first 4 weeks of HAART and then increased without significant associated changes in CD4(+) T cell counts. HAART supplementation with IL-2 was observed to lead to rapid increases in CD4(+) T cells that were accompanied by sjTREC decreases. No notable changes in CD4(+) T cell counts and sjTRECs were seen in patients receiving HAART supplemented with Remune alone. The results indicate CD4(+) T cell maintenance during initial treatment of HIV-1 with HAART and early CD4(+) T cell reconstitution of patients receiving IL-2 with HAART is largely due to thymus-independent mechanisms, with the thymus making a limited contribution.

Immune reconstitution in HIV-1-infected patients.

HIV-1-specific CD8 cytotoxic and CD4 helper T-lymphocytes, which are respectively the central effector and regulatory cells in viral infections, together with fully functional antigen-presenting cells, are essential at all stages of HIV-1 infection to control viral activity. Recent studies indicate that such protective HIV-1-specific immune responses can be preserved/induced in HIV-1-infected individuals, utilizing strategies such as treatment interruption after early HAART. Despite successful combination antiretroviral drug therapy, strong anti-HIV-1 T-cell responses are often not apparent in chronic HIV-1 infection, diminishing the probability of viral eradication. Thus, the therapeutic use of immunization and cytokines are required to induce and steer immunity towards a desirable outcome. Here, we review and discuss therapeutic immunization and immunotherapy with regard to their potential use in the treatment of chronic HIV-1 infection.