Viral replication is a process that involves an extremely high turnover of cellular molecules. Since viruses depend on the host cell to obtain the macromolecules needed for their proper replication, ...they have evolved numerous strategies to shape cellular metabolism and the biosynthesis machinery of the host according to their specific needs. Technologies for the rigorous analysis of metabolic alterations in cells have recently become widely available and have greatly expanded our knowledge of these crucial host-pathogen interactions. We have learned that most viruses enhance specific anabolic pathways and are highly dependent on these alterations. Since uninfected cells are far more plastic in their metabolism, targeting of the virus-induced metabolic alterations is a promising strategy for specific antiviral therapy and has gained great interest recently. In this review, we summarize the current advances in our understanding of metabolic adaptations during viral infections, with a particular focus on the utilization of this information for therapeutic application.
BACKGROUND.Late antibody-mediated rejection (AMR) is a major cause of transplant failure. Potential therapeutic targets are plasma cells (PC) and/or natural killer (NK) cells, both expressing high ...levels of CD38.
METHODS.Here, we report the use of CD38 monoclonal antibody daratumumab (9-month course) in a kidney allograft recipient diagnosed with smoldering myeloma and anti-HLA class II donor-specific antibody (DSA)-positive chronic active AMR 13 years after transplantation. Patient monitoring included serial HLA single antigen testing, peripheral blood immune cell phenotyping, as well as follow-up allograft and bone marrow biopsies at 3 and 9 months, including analyses of rejection-related gene expression patterns.
RESULTS.Daratumumab led to persistent CD138 cell depletion in the bone marrow and blood, and substantially decreased NK cells counts in blood and graft tissue. At the same time, DSA in serum disappeared, and in vitro alloantibody production by CD138 cells enriched from bone marrow aspirates was abrogated. A 3-month follow-up biopsy revealed a complete resolution of microcirculation inflammation (g+ptc3 to 0) and molecular AMR activity (AMR score0.79 to <0.2). The same biopsy showed (subclinical) tubulo-interstitial inflammation, which prompted steroid treatment. Over an observation period of 12 months, graft function stabilized.
CONCLUSIONS.Targeting CD38 for PC and NK cell depletion may be an effective strategy to counteract AMR. Our results may encourage the design of future trials to clarify the role of this innovative treatment concept in organ transplantation.
Rhinoviruses (RVs) are responsible for the majority of upper airway infections; despite their high prevalence and the resulting economic burden, effective treatment is lacking. We report here that RV ...induces metabolic alterations in host cells, which offer an efficient target for antiviral intervention. We show that RV-infected cells rapidly up-regulate glucose uptake in a PI3K-dependent manner. In parallel, infected cells enhance the expression of the PI3K-regulated glucose transporter GLUT1. In-depth metabolomic analysis of RV-infected cells revealed a critical role of glucose mobilization from extracellular and intracellular pools via glycogenolysis for viral replication. Infection resulted in a highly anabolic state, including enhanced nucleotide synthesis and lipogenesis. Consistently, we observed that glucose deprivation from medium and via glycolysis inhibition by 2-deoxyglucose (2-DG) potently impairs viral replication. Metabolomic analysis showed that 2-DG specifically reverts the RV-induced anabolic reprogramming. In addition, treatment with 2-DG inhibited RV infection and inflammation in a murine model. Thus, we demonstrate that the specific metabolic fingerprint of RV infection can be used to identify new targets for therapeutic intervention.
Objectives This study sought to evaluate whether prasugrel may serve as an alternative to clopidogrel in patients with triple therapy. Background Approximately 10% of patients who receive dual ...antiplatelet therapy after percutaneous coronary intervention have an indication for oral anticoagulation and are thus treated with triple therapy. The standard adenosine diphosphate receptor blocker in this setting is clopidogrel. Data regarding prasugrel as part of triple therapy are not available. Methods We analyzed a consecutive series of 377 patients who underwent drug-eluting stent implantation and had an indication for oral anticoagulation between February 2009 and December 2011 and were treated with a 6-month regimen of aspirin and oral anticoagulation with either prasugrel or clopidogrel. The primary endpoint was a composite of Thrombolysis In Myocardial Infarction (TIMI) major and minor bleeding at 6 months. The secondary endpoint was a composite of death, myocardial infarction, ischemic stroke, or definite stent thrombosis. Results Twenty-one patients (5.6%) received prasugrel instead of clopidogrel. These patients had a higher-risk profile at baseline, and the majority had high platelet reactivity to clopidogrel. TIMI major and minor bleeding occurred significantly more often in the prasugrel compared with the clopidogrel group (6 28.6%) vs. 24 6.7%; unadjusted hazard ratio (HR): 4.6, 95% confidence interval CI: 1.9 to 11.4, p < 0.001; adjusted HR: 3.2, 95% CI: 1.1 to 9.1, p = 0.03). There was no significant difference regarding the combined ischemic secondary endpoint (2 9.5% vs. 25 7.0%; unadjusted HR: 1.4, 95% CI: 0.3 to 6.1, p = 0.61). Conclusions These findings suggest that substitution of prasugrel for clopidogrel in patients needing triple therapy increases the risk of bleeding. However, specific randomized trials are needed to define the role of newer adenosine diphosphate receptor antagonists in this setting.
ABSTRACT
T cells must tightly regulate their metabolic processes to cope with varying bioenergetic demands depending on their state of differentiation. The metabolic sensor AMPK is activated in ...states of low energy supply andmodulates cellular metabolism toward a catabolic state. Although this enzyme isknown tobeparticularly active in regulatory T (Treg) cells, its impact on T helper (Th)‐cell differentiation is poorly understood. We investigated the impact of several AMPK activators on Treg‐cell differentiation and found that the direct activator AICAR (5‐aminoimidazole‐4‐carboxamide ribonucleotide), but not the indirect activators metformin and 2‐deoxyglucose, strongly enhanced Treg‐cell induction by specifically enhancing Treg‐cell expansion. Conversely, Th17 generation was impaired by the agent. Further investigation of the metabolic background of our observations revealed that AICAR enhanced both cellular mitochondrogenesis and fatty acid uptake. Consistently, increased Treg induction was entirely reversible on inhibition of fatty acid oxidation, thus confirming the dependence of AICAR's effects on metabolic pathways alterations. Translating our findings to an in vivo model, we found that the substance enhanced Treg cell generation on IL‐2 complex–induced immune stimulation. We provide a previously unrecognized insight into the delicate interplay between immune cell function and metabolism and delineate a potential novel strategy for metabolism‐targeting immunotherapy.—Gualdoni, G. A., Mayer, K. A., Göschl, L., Boucheron, N., Ellmeier, W., Zlabinger, G. J. The AMP analog AICAR modulates the Treg/Th17 axis through enhancement of fatty acid oxidation. FASEB J. 30, 3800–3809 (2016) www.fasebj.org
Current knowledge about the factors correlating with functional decline and subsequent failure of kidney allografts in antibody-mediated rejection (ABMR) is limited. We conducted a cohort study ...involving 75 renal allograft recipients diagnosed with late ABMR occurring at least 6 months after transplantation. The study aimed to examine the correlation of molecular and histologic features with estimated glomerular filtration rate (eGFR) trajectories and death-censored graft survival. We focused on sum scores reflecting histologic ABMR activity versus chronicity and molecular scores of ABMR probability (ABMR
), injury-repair response (IRRAT) and fibrosis (ciprob). In multivariable Cox analysis, a Banff lesion-based chronicity index (ci+ct+cgx2; hazard ratio per interquartile range IQR: 1.97 95% confidence interval: 0.97 to 3.99) and IRRAT (1.93 0.96 to 3.89) showed the strongest associations with graft failure. Among biopsy variables, IRRAT exhibited the highest relative variable importance and emerged as the sole independent predictor of eGFR slope (change per IQR: -4.2 -7.8 to -0.6 mL/min/1.73 m
/year). In contrast, morphologic chronicity associated with baseline eGFR only. We conclude that the extent of molecular injury is a robust predictor of renal function decline. Transcriptome analysis has the potential to improve outcome prediction and possibly identify modifiable injury, guiding targeted therapeutic interventions.
Blockade of interleukin-6 (IL-6) has emerged as a promising therapeutic option for antibody-mediated rejection. Subtherapeutic anti-IL-6 antibody level or treatment cessation following prolonged ...cytokine neutralization may result in proinflammatory rebound phenomena via accumulation of IL-6 and/or modulated gene expression of major components of the IL-6/IL-6 receptor (IL-6R) axis.
We evaluated biologic material obtained from a randomized controlled, double-blind phase 2 trial designed to evaluate the safety and efficacy of the anti-IL-6 monoclonal antibody clazakizumab in late antibody-mediated rejection. Twenty kidney transplant recipients, allocated to clazakizumab or placebo, received 4-weekly doses over 12 wks, followed by a 40-wk extension where all recipients received clazakizumab. Serum proteins were detected using bead-based immunoassays and RNA transcripts using quantitative real-time polymerase chain reaction (peripheral blood) or microarray analysis (serial allograft biopsies).
Clazakizumab treatment resulted in a substantial increase in median total (bound and unbound to drug) serum IL-6 level (1.4, 8015, and 13 600 pg/mL at 0, 12, and 52 wks), but median level of free (unbound to drug) IL-6 did not increase (3.0, 2.3, and 2.3 pg/mL, respectively). Neutralization of IL-6 did not boost soluble IL-6R or leukocyte or allograft expression of IL-6, IL-6R, and glycoprotein 130 mRNA. Cessation of treatment at the end of the trial did not result in a meaningful increase in C-reactive protein or accelerated progression of graft dysfunction during 12 mo of follow-up.
Our results argue against clinically relevant rebound phenomena and modulation of major components of the IL-6/IL-6R axis following prolonged IL-6 neutralization with clazakizumab.
Aim: Sex-specific analyses of direct head-to-head comparisons between newer P2Y12 inhibitors are limited. This study was conducted to assess the efficacy and safety of ticagrelor versus prasugrel in ...women and men with acute coronary syndromes (ACS) planned for an invasive strategy.Methods: This pre-specified analysis of the ISAR-REACT 5 trial included 956 women and 3,062 men with ACS randomly assigned to either ticagrelor or prasugrel. The primary endpoint was the 12-month incidence of death, myocardial infarction, or stroke; the safety endpoint was the 12-month incidence of bleeding (type 3–5 according to the Bleeding Academic Research Consortium BARC).Results: The primary endpoint occurred in 42 women (8.9%) in the ticagrelor group and 39 women (8.3%) in the prasugrel group (hazard ratio HR=1.10, 95% confidence interval CI 0.71–1.70, P=0.657) and in 142 men (9.4%) in the ticagrelor group and 98 men (6.5%) in the prasugrel group (HR=1.47 1.13–1.90, P=0.004; P for interaction Pint=0.275). BARC type 3–5 bleeding occurred in 36 women (9.7%) in the ticagrelor group and 34 women (9.7%) in the prasugrel group (HR=1.04 0.65–1.67, P=0.856) and in 59 men in the ticagrelor group (4.4%) and 46 men (3.6%) in the prasugrel group (HR=1.24 0.85–1.83, P=0.266; Pint=0.571). Conclusions: Although there was no significant interaction between sex and treatment effect of study drugs, the superior efficacy of prasugrel was more evident among men. No difference in bleeding between the two study groups was seen for both women and men.
Transcript analyses highlight an important contribution of natural killer (NK) cells to microvascular inflammation (MVI) in antibody-mediated rejection (ABMR), but only few immunohistologic studies ...have quantified their spatial distribution within graft tissue. This study included 86 kidney transplant recipients who underwent allograft biopsies for a positive donor-specific antibody (DSA) result. NK cells were visualized and quantified within glomeruli and peritubular capillaries (PTC), using immunohistochemistry for CD34 alongside CD16/T-bet double-staining. Staining results were analyzed in relation to histomorphology, microarray analysis utilizing the Molecular Microscope Diagnostic System, functional NK cell genetics, and clinical outcomes. The number of NK cells in glomeruli per mm 2 glomerular area (NK glom ) and PTC per mm 2 cortical area (NK PTC ) was substantially higher in biopsies with ABMR compared to those without rejection, and correlated with MVI scores (NK glom Spearman’s correlation coefficient SCC = 0.55, p < 0.001, NK PTC 0.69, p < 0.001). In parallel, NK cell counts correlated with molecular classifiers reflecting ABMR activity (ABMR prob : NK glom 0.59, NK PTC 0.75) and showed a trend towards higher levels in association with high functional FCGR3A and KLRC2 gene variants. Only NK PTC showed a marginally significant association with allograft function and survival. Our immunohistochemical results support the abundance of NK cells in DSA-positive ABMR.
Antibody-mediated rejection (ABMR) is a leading cause of kidney allograft failure. Its therapy continues to be challenge, and no treatment has been approved for the market thus far.
In this article, ...we discuss the pathophysiology and phenotypic presentation of ABMR, the current level of evidence to support the use of available therapeutic strategies, and the emergence of tailored drugs now being evaluated in systematic clinical trials. We searched PubMed, Clinicaltrials.gov and Citeline's Pharmaprojects for pertinent information on emerging anti-rejection strategies, laying a focus on phase II and III trials.
Currently, we rely on the use of apheresis for alloantibody depletion and intravenous immunoglobulin (referred to as standard of care), preferentially in early active ABMR. Recent systematic trials have questioned the benefits of using the CD20 antibody rituximab or the proteasome inhibitor bortezomib. However, there are now several promising treatment approaches in the pipeline, which are being trialed in phase II and III studies. These include interleukin-6 antagonism, CD38-targeting antibodies, and selective inhibitors of complement. On the basis of the information that has emerged so far, it seems that innovative treatment strategies for clinical use in ABMR may be available within the next 5-10 years.
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