PurposeFunctional status and chronic health status are important baseline characteristics of critically ill patients. The assessment of frailty on admission to the intensive care unit (ICU) may provide objective, prognostic information on baseline health. To determine the impact of frailty on the outcome of critically ill patients, we performed a systematic review and meta-analysis comparing clinical outcomes in frail and non-frail patients admitted to ICU.MethodsWe searched the Cochrane Central Register of Controlled Trials, MEDLINE, EMBASE, PubMed, CINAHL, and Clinicaltrials.gov. All study designs with the exception of narrative reviews, case reports, and editorials were included. Included studies assessed frailty in patients greater than 18 years of age admitted to an ICU and compared outcomes between fit and frail patients. Two reviewers independently applied eligibility criteria, assessed quality, and extracted data. The primary outcomes were hospital and long-term mortality. We also determined the prevalence of frailty, the impact on other patient-centered outcomes such as discharge disposition, and health service utilization such as length of stay.ResultsTen observational studies enrolling a total of 3030 patients (927 frail and 2103 fit patients) were included. The overall quality of studies was moderate. Frailty was associated with higher hospital mortality [relative risk (RR) 1.71; 95% CI 1.43, 2.05; p < 0.00001; I 2 = 32%] and long-term mortality (RR 1.53; 95% CI 1.40, 1.68; p < 0.00001; I 2 = 0%). The pooled prevalence of frailty was 30% (95% CI 29–32%). Frail patients were less likely to be discharged home than fit patients (RR 0.59; 95% CI 0.49, 0.71; p < 0.00001; I 2 = 12%).ConclusionsFrailty is common in patients admitted to ICU and is associated with worsened outcomes. Identification of this previously unrecognized and vulnerable ICU population should act as the impetus for investigating and implementing appropriate care plans for critically ill frail patients. Registration: PROSPERO (ID: CRD42016053910).Electronic supplementary materialThe online version of this article (doi:10.1007/s00134-017-4867-0) contains supplementary material, which is available to authorized users.

Summary. Successful factor (F) VIII replacement therapy in hemophilia A patients is confounded by the generation of inhibitory anti-FVIII antibodies (Ab) in 25-30% of treated patients. These antibodies, termed ÔinhibitorsÕ, significantly increase morbidity within the hemophilia population and lower the quality of life for these patients. For the past 30 years, immune tolerance induction (ITI) has been the standard therapy to elicit immunological tolerance to FVIII in the clinic. ITI works well in approximately 75% of patients, but it is expensive, can take years to show effect and is in many cases practically challenging. Therefore, new immunological tolerance induction strategies are now being designed and tested in hemophilia A animal models. This review attempts to provide a comprehensive description, at both the cellular and molecular levels, of these novel advances in tolerance induction and immunomodulation of FVIII. We begin by briefly reviewing why and how the immune system generates a protective response against exogenous FVIII. This leads to a discussion of the latest advances in FVIII tolerance/immunomodulation technology. These advances include interesting methodologies to induce B cell specific tolerance in FVIII primed humans and animals, as well as newer T cell-specific therapies that modify and/or block co-stimulation. We also discuss methods to manipulate FVIII loading of antigen-presenting cells.

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IntroductionHemophilia A is the most common severe inherited bleeding disorder. Patients with this disease are treated with recombinant or plasma-derived factor VIII (FVIII), which allows them to lead relatively normal lives. 1 In approximately 25% of treated patients, however, the development of anti-FVIII antibodies (FVIII inhibitors) severely complicates FVIII replacement therapy and significantly increases morbidity within the hemophilia population. [2][3][4][5] These antibodies neutralize the procoagulant cofactor activity of FVIII or enhance its clearance from plasma. 5 In economically developed countries, there are 2 approaches to the clinical management of FVIII inhibitors: the treatment or prevention of bleeding and long-term immune tolerance induction (ITI). Bleeding is controlled with variably effective and expensive FVIII-bypassing agents, such as recombinant (r) FVIIa and FEIBA (FVIII-inhibitor bypassing agent). In contrast, ITI is usually attempted through the administration of FVIII at a dose and frequency that depends on the ITI protocol. 6 This treatment approach is practically challenging, costly, and can take months to years to become effective. In light of the significant limitations of the current treatment options, the development of effective, rapid, and economical ITI strategies is a clinical priority.Currently, the most consistent model to study FVIII inhibitors is the hemophilia A mouse (FVIII Ϫ/Ϫ ). [7][8][9] Repeated intravenous infusion of human FVIII into hemophilia A mice results in high titer inhibitor formation. This is a CD4 ϩ T cell-dependent process that requires costimulation. [9][10][11][12] The dependence on CD4 ϩ T cells for inhibitor formation also occurs in humans. Evidence of this first came from hemophilia A patients with FVIII inhibitors who were also HIV ϩ : as patient CD4 ϩ levels declined, there was concomitant disappearance of FVIII inhibitors. 13 Therefore, therapies that blocked T-cell activation seemed to be promising candidates to prevent inhibitor formation.Indeed, Qian et al demonstrated that FVIII Ϫ/Ϫ B7.2 Ϫ/Ϫ doubleknockout mice will not develop anti-FVIII antibodies (Abs) after repeated immunization with FVIII, and that blocking the CD80-CD28 costimulatory interaction with soluble cytotoxic T lymphocyte antigen-4 (CTLA-4)-immunoglobulin (Ig) in FVIII Ϫ/Ϫ mice also prevented inhibitor formation. 10 Additional studies in FVIII Ϫ/Ϫ mice showed that blockade of the CD40-CD40L interaction with anti-CD40L monoclonal Ab (mAb) also protects against FVIII inhibitor formation. 11,12 However, costimulatory blockade must be applied with each FVIII administration to maintain tolerance, and once the blockade is removed, the protective effect is lost. As the potential health risks of long-term costimulatory blockade have not yet been determined and because many hemophilia A patients are treated frequently with FVIII and would most likely need to coadminister blockade with each infusion, this therapy is not a viable option.To reach the clinic, a therapy that induces tole...

This study shows that tolerogenic presentation of cFVIII to the immune system can significantly reduce immunogenicity of the protein.

Previous studies have demonstrated that genetic factors play an important role in determining the likelihood of formation of anti-factor VIII (FVIII) antibodies in haemophilia A patients. We were interested in characterizing the spectrum of FVIII antibody formation and the primary and secondary immune responses after FVIII administration in two different exon 16-disrupted haemophilia A mouse strains, Balb/c and C57BL/6. Balb/c and C57BL/6 E16 haemophilia A mice were used in all experiments. Total FVIII antibodies and FVIII inhibitors were measured using ELISA and Bethesda assays respectively. T- and B-cell cytokines were quantified using ELISA and flow cytometry. FVIII antibodies, but not functional inhibitors were detectable 1 week after the first FVIII treatment in both strains. These antibodies mainly belonged to the IgM and IgA isotypes. After the fourth FVIII treatment, neutralizing anti-FVIII antibodies were detected in both mouse strains: Balb/c (mean inhibitory titer 58 BU) and C57BL/6 (mean inhibitory titer 82 BU). IgG1 levels were similar in both strains but the IgG2A and IgG2B subclasses were higher in C57BL/6 mice. The results of intracellular cytokine staining of T cells indicated that the FVIII-treated C57BL/6 mice produced more IL10 and Th1 cytokines than the FVIII-treated Balb/c mice. These studies show that C57BL/6 mice develop a stronger immune response towards FVIII than Balb/c mice. We propose that the enhanced Th1 and IL10 cytokine micro-environment induced in C57BL/6 mice is responsible for this difference. Therefore, genetic strain-dependent differences must be considered when evaluating immunological outcomes in mouse models of haemophilia A.

Ventilator-associated pneumonia (VAP), an infection of the lower respiratory tract which occurs in association with mechanical ventilation, is one of the most common causes of nosocomial infection in the intensive care unit (ICU). VAP causes significant morbidity and mortality in critically ill patients including increased duration of mechanical ventilation, ICU stay and hospitalization. Current knowledge for its prevention, diagnosis and management is therefore important clinically and is the basis for this review. We discuss recent changes in VAP surveillance nomenclature incorporating ventilator-associated conditions and ventilator-associated events, terms recently proposed by the Centers for Disease Control. To the extent possible, we rely predominantly on data from randomized control trials (RCTs) and meta-analyses.

627 Introduction: Inhibitory antibodies (inhibitors) to exogenous factor VIII (FVIII) are the major complication of treatment with recombinant FVIII for patients with hemophilia A. Inflammatory “danger signals”, such as would be produced by surgical injury, have been hypothesized as important acquired determinants of inhibitor risk. Surgery has been associated with an increased inhibitor risk in observational studies of humans. However, it is not possible to experimentally separate surgical injury from intensive FVIII exposure in humans, and this relationship has not previously been explored in animal models of hemophilia A. We investigated the relationship between surgical injury and FVIII inhibitor development in two distinct mouse models of hemophilia A. Methods: The hemophilia A models used were F8 exon 16 knockout (E16KO) mice and F8 exon 17 knockout mice with the humanized major histocompatibility complex II allele HLA-DRB1*1501 (E17KO/hMHC). The model surgical procedure was an open-and-close laparotomy under isofluorane anaesthesia at 6 to 12 weeks of age. Recombinant human FVIII, with or without lipopolysaccharide (LPS), was administered intravenously through the tail vein. Preoperatively, FVIII was given in doses of 2 units (approximately 0.1 mcg/unit) weekly for 4 weeks; postoperatively FVIII was given in doses of 2 to 6 units daily for 3 to 5 days. Blood was obtained via retro-orbital sampling or cardiac puncture, and plasma was separated by centrifugation. Plasma was assayed for IL-1 and IL-6 concentration by ELISA, for anti-FVIII IgG by ELISA, and for inhibition of FVIII coagulant activity (FVIII:C) by Bethesda assay. Single cell suspensions of splenocytes were analyzed by flow cytometry. Data was analyzed using Student t tests, Mann-Whitney U tests, and chi-square tests. All animal experiments were approved by the Animal Care Committee at Queen's University. Results: In E16KO mice, surgery produced greater than 5-fold increases in IL-1 levels (p=0.0005) and 150-fold increases in IL-6 levels (p=0.000023), compared to FVIII controls in the 24 hrs after the surgical injury. Surgery also resulted in significantly increased expression by splenic dendritic cells of CD80 (p=0.0004), but not of CD40 or CD86. All E16KO mice developed high-titre antibodies (by both ELISA and Bethesda assay) and there was no difference in Bethesda titres between surgery and control groups, either for mice FVIII-naïve at time of surgery (p=0.27), or for mice with FVIII exposure prior to surgery (p=0.66). In contrast to E16KO hemophilic mice, FVIII immune responses were seen in only some E17KO/hMHC animals. Proportions of FVIII-naïve E17KO/hMHC mice that did develop detectable antibodies were similar between surgery and control groups (47% vs. 53% for ELISA, p=0.72; 7% vs. 22% for Bethesda, p=0.19); among mice who developed antibodies, ELISA and Bethesda titres were not significantly different between surgery and control groups (p>0.05). E17KO/hMHC mice were exposed to FVIII, and those that were tolerant to FVIII (ie. did not have antibodies detectable by ELISA) then had either surgery with post-operative FVIII exposure, FVIII without surgery, or FVIII and LPS. No FVIII-tolerant E17KO/hMHC developed antibodies detectable by ELISA after surgery or after FVIII exposure alone, but 100% of FVIII-LPS-exposed mice developed antibodies (p=0.001). Conclusions: Although laparotomy produces acute increases in the inflammatory cytokines IL-1 and IL-6 and upregulates expression of the costimulatory molecule CD80 on antigen presenting cells, E16KO mice that underwent laparotomy did not have greater immunologic responses to FVIII than those who did not. FVIII-naïve E17KO/hMHC mice who underwent surgery were no more likely to develop detectable antibodies than those who did not, and surgery did not result in higher-titre immune responses. In E17KO/hMHC mice who were immunologically tolerant to FVIII, surgery did not break this tolerance, although coadministration of LPS and FVIII did; tolerance could be broken in these mice, but was not broken by surgical injury. Given the limitations of existing clinical research in this area, our results indicate that understanding of specific inflammatory stimuli involved in FVIII inhibitor development in humans should be obtained before proceeding with the assumption that surgical injury alone is a significant risk factor for inhibitors in patients with hemophilia A. Disclosures: Moorehead: Baxter Biosciences: Honoraria, Travel funding for educational meetings Other; Bayer: Honoraria, Travel funding for educational meetings, Travel funding for educational meetings Other. Steinitz:Baxter BioScience: Employment. Reipert:Baxter Biosciences: Employment.