Immune-modulating Interventions Research Articles

Differential Fibrinolysis Profile in COVID-19 Patients Dependent on Immunosuppressive Treatment Regimen: A Nested Case-Control Study

Introduction: Severe coronavirus disease 2019 (COVID-19) is associated with thrombotic complications, despite prophylactic and therapeutic anticoagulation. The disease course of critically ill COVID-19 patients has been characterized by severe hypercoagulability and hypofibrinolysis leading to an increased risk of venous thromboembolism. In COVID-19 (low molecular weight) heparins do not provide sufficient protection against venous thromboembolism. Since the start of the COVID-19 pandemic, several immune modulatory interventions have been introduced to improve outcome, including dexamethasone and tocilizumab. Whether dexamethasone and tocilizumab would alter the course of hypercoagulability by modifying inflammation, is unknown. Tocilizumab, that reduces IL-6 binding to its cellular receptors, has been shown to reduce the plasma plasminogen activator inhibitor-1 (PAI-1). On the other hand, dexamethasone can induce PAI-1 release. Data on the net impact of dexamethasone and tocilizumab on fibrinolysis in critically ill COVID-19 patients is lacking. Therefore, we aimed to characterize the fibrinolytic profile of severe COVID-19 patients on different treatment regimens and to unravel underlying mechanisms of the hypofibrinolytic state of these patients. Methods: A nested case-control study within the Maastricht Intensive Care COVID (MaastrICCht) cohort on mechanically ventilated COVID-19 patients was conducted. Patients receiving tocilizumab and dexamethasone (toci group) were age- and sex-matched with patients receiving only dexamethasone (dexa group) and patients receiving neither tocilizumab nor dexamethasone (control group). Whole blood was collected from these patients at three different time points after intubation (week 1, 2, and 3). The dexa and toci group received dexamethasone treatment before intubation and the toci group received one bolus of tocilizumab before or on the day of intubation. All blood samples were collected thereafter. Whole blood tissue plasminogen activator rotational thromboelastometry (tPA-ROTEM) was performed and subsequently inflammatory markers (c-reactive protein (CRP), ferritin, IL-6, fibrinogen), fibrinolysis parameters (tPA, PAI-1, thrombin activatable fibrinolysis inhibitor (TAFI), plasmin-alpha-2-antiplasmin complex (PAP)) and coagulation biomarkers (D-dimer, prothrombin fragment 1.2 (F1.2)) were measured in plasma samples. All markers were analyzed with linear mixed-effects regression models to estimate the differences between treatment groups over time. Results: Matching showed similar groups (Table 1.) for the baseline characteristics. At week 1 the dexagroup's IL-6 level was significantly lower, whereas the toci group's IL-6 level was significantly higher compared to the control group (difference[95%CI]: -198.37 [-350.86- -45.88], p=0.017 and 269.59 [113.91-425.27], p=0.002, respectively). CRP levels were significantly lower at week 1 in both dexa and toci groups compared to the control group (median [IQR] 60.50 [30.75 - 131.25] and 18.50 [6.00 - 60.00] vs. 296.00 [223.75 - 347.00]) suggesting effective immune suppression. Divergent fibrinolysis was seen at week 1 by tPA-ROTEM showing lower lysis time (LT) in the toci group compared to the control group (difference[95%CI]: -1,759.21 [-2752.05 - -766.34; p=0.002), whereas the dexa group did not differ. Interestingly, LT decreased over time in the control group, while an increase was seen in the toci group (Figure 1.). PAI-1 levels were lower in week 1 in the toci group compared to the control group (difference [95%CI] -7.32 [-14.95 - 0.30], p=0.071) and the tocigroup showed an overall increase in PAI-1 levels, while the control and dexa group showed a decrease over time. High TAFI and tPA levels were observed in all groups at week 1 and over time regardless of the treatment regimens. Coagulation biomarkers D-dimer and prothrombin fragment 1.2 were elevated but did not differ or change over time between groups. Conclusions: The differences and changes over time revealed by tPA-ROTEM and the fibrinolysis markers between the three different treatment regimens show the direct interaction between inflammation and fibrinolysis in these patients. The lower LT and PAI-1 levels upon tocilizumab treatment could be indicative for better fibrinolytic activity in these patients. This study was supported by the Dutch Covid and Thrombosis Coalition (DCTC). Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

Fasting-induced FOXO4 blunts human CD4+ T helper cell responsiveness

Abstract Intermittent fasting blunts inflammation in asthma and rheumatoid arthritis, suggesting that fasting may be exploited as an immune-modulatory intervention. However, mechanisms underpinning anti-inflammatory effects of fasting remain poorly characterized. Here, we show that fasting in humans is sufficient to blunt CD4+ T helper cell responsiveness. RNA-seq and flow cytometric immunophenotyping of peripheral blood mononuclear cells (PBMCs) from volunteers subjected to overnight or 24-hour fasting, and 3-hours of refeeding implicate that fasting blunts CD4+ T helper cell activation and differentiation. Transcriptomic analysis reveal that the longer fast-duration has a more robust effect on CD4+ T cell biology. Through bioinformatic analyses, we identify the transcription factor FOXO4 and its canonical target FKBP5 as a potential fasting-responsive regulatory axis. Genetic gain- or loss-of-function of FOXO4 and FKBP5 is sufficient to modulate Th1 and Th17 cytokine production. Moreover, we find that fasting-induced or genetic overexpression of FOXO4 and FKBP5 is sufficient to downregulate mTORC1 signaling and suppress STAT1/3 activation. Our results identify FOXO4-FKBP5 as a novel fasting-induced, STAT-mediated, regulatory pathway to blunt human CD4+ T helper cell responsiveness.

Neuropathogenesis of acute coronavirus disease 2019.

Over the course of the coronavirus disease (COVID-19) pandemic, it has become increasingly clear that there is a high prevalence of neurological complications in people infected with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Studies of central nervous system (CNS) tissue in brain model systems and from adults with acute SARS-CoV-2 infection have begun to uncover potential mechanisms for neurological damage during COVID-19. These studies suggest that direct viral invasion of the CNS occurs in a subset of cases but does not frequently cause overt viral meningoencephalitis. Vascular abnormalities including microvascular thrombi and endothelial activation, as well as parainfectious processes, including CNS specific immune responses, may contribute to neurological symptoms during acute SARS-CoV-2 infection. Neuroimmune perturbations and vascular inflammation observed in people with COVID-19 may warrant investigation of immune-modulating interventions to ameliorate neurological complications associated with acute SARS-CoV-2 infection. These therapies may also impact the trajectory of potential long-term complications of COVID-19.

What Does Immunology Have to Do With Normal Brain Development and the Pathophysiology Underlying Tourette Syndrome and Related Neuropsychiatric Disorders?

Objective: The goal of this article is to review the past decade's literature and provide a critical commentary on the involvement of immunological mechanisms in normal brain development, as well as its role in the pathophysiology of Tourette syndrome, other Chronic tic disorders (CTD), and related neuropsychiatric disorders including Obsessive-compulsive disorder (OCD) and Attention deficit hyperactivity disorder (ADHD).Methods: We conducted a literature search using the Medline/PubMed and EMBASE electronic databases to locate relevant articles and abstracts published between 2009 and 2020, using a comprehensive list of search terms related to immune mechanisms and the diseases of interest, including both clinical and animal model studies.Results: The cellular and molecular processes that constitute our “immune system” are crucial to normal brain development and the formation and maintenance of neural circuits. It is also increasingly evident that innate and adaptive systemic immune pathways, as well as neuroinflammatory mechanisms, play an important role in the pathobiology of at least a subset of individuals with Tourette syndrome and related neuropsychiatric disorders In the conceptual framework of the holobiont theory, emerging evidence points also to the importance of the “microbiota-gut-brain axis” in the pathobiology of these neurodevelopmental disorders.Conclusions: Neural development is an enormously complex and dynamic process. Immunological pathways are implicated in several early neurodevelopmental processes including the formation and refinement of neural circuits. Hyper-reactivity of systemic immune pathways and neuroinflammation may contribute to the natural fluctuations of the core behavioral features of CTD, OCD, and ADHD. There is still limited knowledge of the efficacy of direct and indirect (i.e., through environmental modifications) immune-modulatory interventions in the treatment of these disorders. Future research also needs to focus on the key molecular pathways through which dysbiosis of different tissue microbiota influence neuroimmune interactions in these disorders, and how microbiota modification could modify their natural history. It is also possible that valid biomarkers will emerge that will guide a more personalized approach to the treatment of these disorders.

The clinical value of a day one post-operative absolute CD4 count in elective neoplastic brain tumor surgery – A prospective cohort study from a single South African neurosurgical center

IntroductionMultiple simultaneously occurring intra-operative immune modulating interventions make it impossible to compare, the pre-operative day and day one post-operative absolute CD4 counts, and assume one has a measure of the pure surgical impact on this variable. Materials and methodsWe conducted a prospective cohort study by consecutively enrolling 41 elective subjects, with neoplastic brain tumours, in which we obtained a pre-operative day CD4 count and a day one post-operative CD4 count. Data collected included age, HIV status, pre-operative corticosteroid therapy, pre-operative day CD4 count, type of craniotomy, blood loss, duration of surgery, extent of resection, day one post-operative CD4 count, histological diagnosis, day-7 nosocomial infection incidence and Gram-stain result, and Glasgow Outcome Score. ResultsRegarding HIV status 29/41 (71%) subjects were HIV negative and 12/41 (29%) subjects were HIV positive. High significance was demonstrated between the pre-operative day CD4 count and the post-operative day CD4 count (p = 0.0001). While no significance was demonstrated (p = 0.51), a clinical trend was suggested where more than 1000 ml of blood loss had a detrimental effect on the day one post-operative CD4 count, which was often below 500 cells/mm. Again, while no significance was demonstrated (p = 0.13), a clinical trend was suggested where the longer the duration of surgery, the lower the day one post-operative CD4 count would be. No significance was demonstrated between day one post-operative CD4 count and day 7 nosocomial infection incidence (p = 0.35). A clinical trend was however demonstrated where a lower day one post-operative CD4 count suggested an increased risk of incurring this complication. Finally, significance was demonstrated between the day one post-operative CD4 count and the nosocomial infection gram stain result (p = 0.0058). ConclusionThe highly significantly similar pre-operative day CD4 count, to the day one post-operative CD4 count indicated that overall, the elective surgical procedures considered, had an insignificant effect.

Magnetic resonance imaging of stem cell-macrophage interactions with ferumoxytol and ferumoxytol-derived nanoparticles.

"Off the shelf" allogeneic stem cell transplants and stem cell nano-composites are being used for the treatment of degenerative bone diseases. However, major and minor histocompatibility antigens of therapeutic cell transplants can be recognized as foreign and lead to their rejection by the host immune system. If a host immune response is identified within the first week post-transplant, immune modulating therapies could be applied to prevent graft failure and support engraftment. Ferumoxytol (Feraheme™) is an FDA approved iron oxide nanoparticle preparation for the treatment of anemia in patients. Ferumoxytol can be used "off label" as an magnetic resonance (MR) contrast agent, as these nanoparticles provide measurable signal changes on magnetic resonance imaging (MRI). In this focused review article, we will discuss three methods to localize and identify innate immune responses to stem cell transplants using ferumoxytol-enhanced MRI, which are based on tracking stem cells, tracking macrophages or detecting mediators of cell death: (a) monitor MRI signal changes of ferumoxytol-labeled stem cells in the presence or absence of innate immune responses, (b) monitor influx of ferumoxytol-labeled macrophages into stem cell implants, and (c) monitor apoptosis of stem cell implants with caspase-3 activatable nanoparticles. These techniques can detect transplant failure at an early stage, when immune-modulating interventions can potentially preserve the viability of the cell transplants and thereby improve bone and cartilage repair outcomes. Approaches 1 and 2 are immediately translatable to clinical practice. This article is categorized under: Diagnostic Tools > in vivo Nanodiagnostics and Imaging Nanotechnology Approaches to Biology > Cells at the Nanoscale Diagnostic Tools > Biosensing.

Immune Checkpoint Inhibitor Related Neuropathic Adverse Effects on Cancer Patients

With the recent development and clinical application, immune checkpoint inhibitors (ICIs) intervention is being increasingly common for multiple malignancies. With these, prospect on focus creates an increasing necessity for an early recognition with proper documentation of upcoming treatment-related toxicities. These treatment-related toxicities are generally termed as immune-related adverse effects (irAEs) [1]. It is a known fact that the upregulation of T-cell initiates autoimmunity resulting in these irAEs. The review focuses on increasing events of neuropathy associated with immunecheckpoint inhibitors, which is one of the rare neurological irAEs, therefore, the least reviewed. The severity and distribution of neurologic toxicities are important deciding factors for its management (CNS vs. PNS), although there is no strong evidence for patients treated with ICIs are specifically affected by the use of immune-modulating interventions. Furthermore, the review discusses on pathophysiology, incidence, clinical presentation, diagnosis, and management of neuropathies as a result of ICIs. Early administration of high-dose corticosteroids is the main management of neuropathies especially for grade 3 or 4 irAEs initial cessation of ICI therapy with continued steroids which are necessary. However, the optimal duration of ICI therapy to minimize the risk of toxicity should be kept under consideration.

Multiomics modeling of the immunome, transcriptome, microbiome, proteome and metabolome adaptations during human pregnancy.

MotivationMultiple biological clocks govern a healthy pregnancy. These biological mechanisms produce immunologic, metabolomic, proteomic, genomic and microbiomic adaptations during the course of pregnancy. Modeling the chronology of these adaptations during full-term pregnancy provides the frameworks for future studies examining deviations implicated in pregnancy-related pathologies including preterm birth and preeclampsia.ResultsWe performed a multiomics analysis of 51 samples from 17 pregnant women, delivering at term. The datasets included measurements from the immunome, transcriptome, microbiome, proteome and metabolome of samples obtained simultaneously from the same patients. Multivariate predictive modeling using the Elastic Net (EN) algorithm was used to measure the ability of each dataset to predict gestational age. Using stacked generalization, these datasets were combined into a single model. This model not only significantly increased predictive power by combining all datasets, but also revealed novel interactions between different biological modalities. Future work includes expansion of the cohort to preterm-enriched populations and in vivo analysis of immune-modulating interventions based on the mechanisms identified.Availability and implementationDatasets and scripts for reproduction of results are available through: https://nalab.stanford.edu/multiomics-pregnancy/.Supplementary information Supplementary data are available at Bioinformatics online.

Abstract 3101: Influence of targeted knockout of the BRCA1 gene on the pharmacologic profile of the mouse breast cancer cell line EMT6 in vitro and in vivo

Abstract Around 10% of breast cancer cases are attributed to genetic disorders like mutations in BRCA-1/2 genes. Targeted therapy of BRCA-deficient cancers has been achieved using poly(ADP-ribose) polymerase (PARP) inhibitors, which block BRCA-independent DNA repair. To study the effect of this common mutation on sensitivity towards innovative therapies in more detail, we knocked out the BRCA1 gene in the murine EMT6 breast cancer cell line. Subsequently, we analyzed the sensitivity towards PARP as well as checkpoint (CP) inhibitors in the mutated as well as the parental line in vitro and in vivo. The EMT6/BRCA1-/- cell line was created by a CRISPR/CAS9 based removal of Exon2 of the BRCA1 gene. The homozygous clone of the modified cell line was used for drug testing in comparison to the wildtype (wt) cell line. PARP inhibitors Niraparib, Rucaparib, Talazoparib and Olaparib were investigated in EMT6/BRCA1wt as well as EMT6/BRCA1-/- in vitro in 2D as well as 3D cell culture using different cell concentrations. The latter showed higher sensitivity towards Talazoparib and Olaparib in 2D assays: The respective IC50 values were 2-4 times lower in the EMT6/BRCA1-/- as compared to EMT6/BRCA1wt. In 3D assays Niraparib, Rucaparib and Talazoparib showed pronounced activity in the EMT6/BRCA1-/- : IC50 values depicted a 2-3fold difference between the two investigated lines. To further characterize the two lines, tumor growth and sensitivity towards PARP as well as CP inhibitors was determined in vivo. Tumor growth behavior of subcutaneously implanted breast cancer cells was similar in both lines: mean doubling times were 1.9 (± 0.38) days for EMT6/BRCA1-/- and 1.62 (± 0.37) days for EMT6/BRCA1wt . Both lines showed a distinct sensitivity profile towards CP inhibitors: anti-CTLA4 was more active in EMT6/BRCA1-/- : optimal T/C (test/control) value of 22% (KO line) was accompanied by 34.9% in the parental line. In contrast, anti-PD1 treatment led to optimal T/C values of 30.9% in the wt line and 54.8% in the KO line. The evaluation of Niraparib as well as Olaparib in mono-and combined therapy with anti-CTLA4 and anti-PD1 in vivo is currently under investigation. Weekly cytokine analysis in the serum of tumor bearing mice will elucidate possible interactions between PARP and CP inhibitors and give guidance to optimal combination and schedules. We expect that further evaluation of PARP inhibitors in combination with different immune modulatory interventions in our mouse breast cancer model will increase the clinical utility of this strategy for the treatment of patients with BRCA1 mutated cancers. In general, the possibility to compare a mutated vs a parental line in vivo will help to identify novel promising combination as well as patient stratification strategies for immuno-oncology. Citation Format: Anya Avrutskaya, Cordula Tschuch, William Durham, Gerhard Kelter, Astrid Jensen, Armin Maier, Aidan Synnott, Anne-Marie Zuurmond, Julia Schüler. Influence of targeted knockout of the BRCA1 gene on the pharmacologic profile of the mouse breast cancer cell line EMT6 in vitro and in vivo [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 3101.

The Potential for Topical Probiotic Treatment of Chronic Rhinosinusitis, a Personal Perspective.

This review describes the rationale for topical probiotic intervention, the obstacles we are facing and a strategy for future research in the use of probiotics to modify CRS symptoms and disease expression. Recent advances in molecular microbiology has revealed a plethora of microbial DNA in the nasal cavity and sinuses of healthy subjects as well as in chronic sinusitis (CRS) patients. An infection is today rather seen as an imbalance between the commensal microbiome and the bacterial pathogens, resulting in a reduction in commensal bacterial diversity, combined with an increase in the growth of microbes eliciting an inflammatory response. This will in turn lead to the clinical symptoms of sinusitis. Probiotics (microorganisms that confer a health benefit) can be used either as a form of living antibiotics treatment, or as an immune-modulatory intervention. Topical probiotics, which is the focus of this review, have shown efficacy in a limited number of trials in otitis media and tonsillitis, but to date not in CRS. Although bacterial interference capacity against pathogens can be determined in in vitro experiments, it may not translate to a health benefit. This limits the role of laboratory research in identifying probiotic strains with a clinical benefit. To gain more clinical experience without further delay, I recommend future research to focus on empirical clinical trials in well-defined CRS patient populations and study the underlying mechanisms in more detail once a clinical benefit has been established.

Sex differences in regulatory cells in experimental stroke

Stroke is the leading cause of disability in the United States. Sex differences, including smaller infarcts in females and greater involvement of immune-mediated inflammation in males may affect the efficacy of immune-modulating interventions. To address these differences, we sought to identify distinct stroke-modifying mechanisms in female vs. male mice. The current study demonstrated smaller infarcts and increased levels of regulatory CD19+CD5+CD1dhi B10 cells as well as anti-inflammatory CD11b+CD206+ microglia/macrophages in the ipsilateral vs. contralateral hemisphere of female but not male mice undergoing 60min middle cerebral artery occlusion followed by 96h of reperfusion. Moreover, female mice with MCAO had increased total spleen cell numbers but lower B10 levels in spleens. These results elucidate differing sex-dependent regulatory mechanisms that account for diminished stroke severity in females and underscore the need to test immune-modulating therapies for stroke in both males and females.

Efficacy of PD-1 inhibitors in patients with metastatic non-small cell lung cancer (NSCLC) with KRAS or EGFR T790M mutations.

e20513 Background: Immune checkpoint blockade(ICB) has revolutionized the treatment of progressive NSCLC with its durable benefit when compared to cytotoxic agents. In the era of personalized medicine, there is a need to identify effective predictive biomarkers to detect exceptional responders to ICB. Immune modulating interventions with cytotoxic or biologic agents can maximize clinical responses from ICB in poorly immunogenic tumors. KRAS mutations are a negative prognostic factor for survival and generally lack targeted therapies. The T790M mutation in EGFR is the most common cause of acquired resistance to first line TKIs. As a group, patients with EGFR mutations generally do not derive clinical benefit from ICB versus cytotoxic chemotherapy. Preclinical data suggests that mutations like T790 m are associated with higher immunogenicity leading to avid stimulation of antigen specific T-cells (Ofuzi et al, 2014) and better response to ICB (Yamada, 2013). However, the efficacy of ICB by specific molecular mutations remains poorly defined. Methods: We reviewed data for 83 pts with recurrent or progressive metastatic lung cancer treated with nivolumab from June 2015-Dec 2016. All pts were treated with ICB as a second or subsequent line of treatment. The patients were assessed for pathology, mutational status and overall survival. Mutational status was checked on either tissue biopsy or serum samples submitted for proteomic veristrat/genestrat (Biodesix Inc., Boulder, CO, USA) assay. Results: Of the 83 patients treated with nivolumab, 65 patients were found to have NSCLC. Eleven pts were found to have KRAS mutation which was further subdivided as: 6 pts with KRAS G12C, 4 with KRAS G12V, 1 with KRAS G12D. Two pts were found to have T790M mutation. 81%(9/11) pts with KRAS mutation died. Median survival in pts with KRAS G12C mutation was 10 weeks and KRAS G12V was 12 weeks (p = 0.17). Median survival was not reached for patients with T790M mutation. Conclusions: KRAS mutations tend to have a shorter overall survival with ICB as compared to patients with EGFR T790M mutations. Further studies are necessary to isolate poorly immunogenic subtypes of NSCLC and develop novel treatment approaches to optimize outcomes.

MON-P087: Nutritional and Immune Modulatory Intervention in Surgical Gastric Cancer Patients

MON-P087: Nutritional and Immune Modulatory Intervention in Surgical Gastric Cancer Patients

T-Prolymphocytic Leukemia Is Sensitive to Polyclonal T Cell-Derived Graft-Versus-Leukemia Effects: Evidence from Minimal Residual Disease Kinetics and TCR Repertoire Diversity Analyses

▪ INTRODUCTIONT-prolymphocytic leukemia (T-PLL) is a rare T cell malignancy with an aggressive clinical course. Preliminary clinical data suggest that allogeneic stem cell transplantation (alloSCT) may provide long-term disease control in a proportion of patients. However, direct evidence that graft-versus-leukemia (GVL) activity is indeed effective in T-PLL is lacking. We sought to investigate GVL in T-PLL by correlating minimal residual disease (MRD) kinetics with immune modulatory interventions (immunosuppression tapering, donor lymphocyte infusions (DLI), chronic graft-versus-host disease (cGvHD)), and T cell receptor (TCR) repertoire diversity alterations after alloSCT. METHODSThe study sample consisted of 10 consecutive patients who received alloSCT for T-PLL at the University of Heidelberg between 2007 and 2015. Quantitative MRD monitoring was performed using clone-specific real-time quantitative PCR (RQ-PCR) of clonal TCR beta (TRB) and/or gamma (TRG) gene rearrangements. Data interpretation followed EuroMRD guidelines. In selected patients, TCR repertoire diversity was analyzed longitudinally by next-generation sequencing (NGS). TRBV-TRBD-TRBJ gene rearrangements were amplified according to BIOMED2 protocol on genomic DNA. PCR products were sequenced on Illumina's MiSeq platform. NGS data were analyzed through a purpose-built bioinformatics immunoprofiler (EuroClonality-NGS consortium). Rearrangements with very similar junctional amino acid sequences and identical TRBV and TRBJ gene usage were defined as clonotypes. RESULTSPatients underwent alloSCT in remission after first-line (8) or salvage (2) alemtuzumab-based therapy. 5 patients were allografted with an unrelated donor, 4 with a related donor, and one received haploidentical alloSCT. Conditioning was fludarabine with cyclophosphamide and/or total body irradiation-based. All patients had a cytological complete response (CR) after alloSCT. 2 patients died early because of acute GvHD, and one had no MRD marker, leaving 7 patients for MRD monitoring. Of these, 3 were MRD- at alloSCT, whereas 5 patients remained or became MRD+ early after alloSCT. In all of these 5 patients, immunosuppression tapering (3) or DLI (2) resulted in significant reduction of MRD levels (range 1-3 log) and was accompanied by cGvHD in 3 patients. However, durable MRD- was obtained in only 2 patients (alive 81+ and 12+ months post transplant), whilst MRD re-increased in 3 patients after 5-28 months despite ongoing cGvHD in one of them. NGS of the TCR repertoire was performed longitudinally in 3 patients with the longest follow-up. A total of 104 samples (blood (n=91) and BM (n=10) plus 3 donor blood samples) were sequenced. The sample at diagnosis showed one or two major clonotypes in all 3 sequenced T-PLLs, predominantly reflecting a mono- or biallelic leukemic TRB gene rearrangement. Kinetics of this leukemic clonotype followed kinetics of RQ-PCR MRD measurement, demonstrating that NGS can be used to quantify MRD in T cell lymphoma. Immediately after transplantation, the TRB repertoire was heavily skewed in all 3 patients, but recovered over time. Also in all 3 patients, MRD responses were reproducibly associated with a shift from a clonal, T-PLL-driven profile to a polyclonal signature. This corresponded to the donor clonotype repertoire and disappeared with increasing MRD levels. In each of the samples after alloSCT, several expanded non-leukemic clonotypes were observed at a maximum frequency from 3% to 54% of total TRB sequences. However, during MRD response, novel dominant clonotypes that could explain a clonal GVL effect did not emerge. Figure 1 shows an example of a patient repeatedly showing MRD response to immune interventions. Currently, 5 patients are alive and in cytological CR (4-81 months after alloSCT), translating into a median relapse-free survival of 40 months. CONCLUSIONSThe MRD responses to immune interventions observed here provide the first direct evidence for the efficacy of GVL in T-PLL. However, the GVL effect in T-PLL appears to be often only limited or transient. It also does not seem to be caused by the emergence of novel dominant T cell clones but is rather relying on a poly-/oligoclonal T cell response. [Display omitted] DisclosuresNo relevant conflicts of interest to declare.

Immune modulation as a therapeutic strategy in bone regeneration.

We summarize research approaches and findings on bone healing and regeneration that were presented at a workshop at the 60th annual meeting of the Orthopedic Research Society (ORS) in New Orleans in 2014. The workshop was designed to discuss the role of inflammation in bone regeneration in the context of fundamental biology, and to develop therapeutic strategies that involve immune modulation. Delayed or non-healing of bone is a major clinical problem, with around 10% of fracture patients suffering from unsatisfying healing outcomes. Inflammation is traditionally seen as a defense mechanism, but was recently found essential in supporting and modulating regenerative cascades. In bone healing, macrophages and T- and B-cells interact with progenitor cells, bone forming osteoblasts and remodeling osteoclasts. Among the cells of the innate immunity, macrophages are promising candidates for targets in immune-modulatory interventions that would overcome complications in bone healing and bone-related diseases. Among the cells of the adaptive immune system, CD8+ T cells have been shown to have a negative impact on bone fracture healing outcome, whereas regulatory T cells could be promising candidates that have a positive, modulating effect on bone fracture healing. This workshop addressed recent advances and key challenges in this exciting interdisciplinary research field.

HIV‐associated chronic immune activation

Systemic chronic immune activation is considered today as the driving force of CD4(+) T-cell depletion and acquired immunodeficiency syndrome (AIDS). A residual chronic immune activation persists even in HIV-infected patients in which viral replication is successfully inhibited by anti-retroviral therapy, with the extent of this residual immune activation being associated with CD4(+) T-cell loss. Unfortunately, the causal link between chronic immune activation and CD4(+) T-cell loss has not been formally established. This article provides first a brief historical overview on how the perception of the causative role of immune activation has changed over the years and lists the different kinds of immune activation characteristic of human immunodeficiency virus (HIV) infection. The mechanisms proposed to explain the chronic immune activation are multiple and are enumerated here, as well as the mechanisms proposed on how chronic immune activation could lead to AIDS. In addition, we summarize the lessons learned from natural hosts that know how to 'show AIDS the door', and discuss how these studies informed the design of novel immune modulatory interventions that are currently being tested. Finally, we review the current approaches aimed at targeting chronic immune activation and evoke future perspectives.

Immune-modulating interventions in critically ill septic patients: pharmacological options

Critically ill patients with severe sepsis and septic shock are characterized by a systemic inflammatory response consisting of pro- and anti-inflammatory mediators. Owing to the high mortality of severe sepsis, great efforts have been undertaken within the last 30 years to develop an immune-modulating therapy to improve survival. Relatively few pharmacological immune-modulating interventions have demonstrated a beneficial impact on survival, while other studies have shown a detrimental effect of such interventions. Among the immune-modulating interventions tested, activated protein C and intensive insulin therapy have been shown to improve survival in septic patients. However, in later studies, it has been difficult to reproduce these beneficial effects. There appears to be a discrepancy between the promising effects of immune-modulating interventions in animal studies and the effects seen in the clinical setting. In the future, the onset of the proinflammatory versus the anti-inflammatory response must be better defined and the timing of treatment with immune-modulating agents should be better managed.

Sepsis and Therapeutic Hypercapnia

Sepsis and Therapeutic Hypercapnia

Induction of immune tolerance: a role for Natural killer T lymphocytes?

The ability of the immune system to distinguish between harmful and harmless antigens is essential for mounting protective immune responses and preventing the induction of pathology. Tolerance is a mechanism that prevents or suppresses potentially injurious immune responses. Natural killer T (NKT) lymphocytes, a subset of regulatory T lymphocytes, can induce pro-inflammatory or anti-inflammatory immune responses. This subset of cells appears to be crucial for induction of tolerance by several immune-modulatory interventions; these include immune manipulations in the setting of transplantation, induction of tolerance by introduction of antigen into immune-privileged sites, and oral administration of disease-associated-antigen. The ability to predict whether tolerance or immunity will be generated in a given situation is essential for development of NKT lymphocyte-based immune-modulatory treatments. The role of NKT lymphocytes in these settings, and the requirements for development of tolerance, rather than immunity, are discussed.

Update on the Mechanisms of Immune Suppression of Injury and Immune Modulation

Major trauma results in massive impairment of immunologic reactivity, the clinical consequence of which consists in the high susceptibility of the traumatized individual toward serious infection. Whereas parts of the immune system are stimulated within a systemic, nondiscriminant, excessive whole-body inflammation, other functions within the complex of cell-mediated immunity (CMI) are dramatically paralyzed. Immune abnormalities in the aftermath of trauma occur in a sequence of states of cellular activation and within a complex order of events that is not yet well understood. Traumatic stress is causing disintegration of the intact monocyte (Mphi)-T cell interaction, which is associated with profound changes in Mphi forward-regulatory capacities and substantial depression of T cell function. Extensive tissue destruction results in the generation of numerous stimuli, such as phagocytosis, immune complexes, complement split products, and endo- and exotoxins, all of which contribute to excessive Mphi activation. Mphi then rapidly produce and release prostaglandin E2 (PGE2), a powerful endogenous immune suppressant. PGE2 is an inhibitor of T cell mitogenesis, interleukin 2 (IL-2) production, and IL-2 receptor expression; and it has a massive impact on the quality of B cell antibody synthesis. Most importantly, PGE2 represents an important cofactor for the induction of T-helper lymphocyte (TH) activity toward the TH2 direction. TH2 cells are associated with the synthesis of immunosuppressive cytokines, such as IL-4 and IL-10. Although immunosuppressive substrates are inhibitory for TH1 cells-the functional carriers of CMI-they support TH2 activity, which predisposes the host to develop infection. The endogenous ability of the organism to survive overwhelming trauma is insufficient and requires major exogenous support. Immune modulatory interventions, depending on the immune abnormalities seen in the traumatized host, should be started as early as possible after trauma in a preventive fashion to protect against organ tissue destruction. Ideally, it should protect all cellular host defense compartments from hyperactivation as well as from exhaustion. We do believe that only a combination of drugs can effectively control the posttraumatic dyshomeostasis of the various cell systems.