Lung transplantation, a cure for a number of end-stage lung diseases, continues to have the worst long-term outcomes when compared with other solid organ transplants. Preclinical modeling of the most common and serious lung transplantation complications are essential to better understand and mitigate the pathophysiological processes that lead to these complications. Various animal and in vitro models of lung transplant complications now exist and each of these models has unique strengths. However, significant issues, such as the required technical expertise as well as the robustness and clinical usefulness of these models, remain to be overcome or clarified. The National Heart, Lung, and Blood Institute (NHLBI) convened a workshop in March 2016 to review the state of preclinical science addressing the three most important complications of lung transplantation: primary graft dysfunction (PGD), acute rejection (AR), and chronic lung allograft dysfunction (CLAD). In addition, the participants of the workshop were tasked to make consensus recommendations on the best use of these complimentary models to close our knowledge gaps in PGD, AR, and CLAD. Their reviews and recommendations are summarized in this report. Furthermore, the participants outlined opportunities to collaborate and directions to accelerate research using these preclinical models.
Vibha N. Lama, John A. Belperio, Jason D. Christie, Souheil El-Chemaly, Michael C. Fishbein, Andrew E. Gelman, Wayne W. Hancock, Shaf Keshavjee, Daniel Kreisel, Victor E. Laubach, Mark R. Looney, John F. McDyer, Thalachallour Mohanakumar, Rebecca A. Shilling, Angela Panoskaltsis-Mortari, David S. Wilkes, Jerry P. Eu, Mark R. Nicolls
Abnormal lipid metabolism may contribute to myocardial injury and remodeling. To determine whether accumulation of very long–chain ceramides occurs in human failing myocardium, we analyzed myocardial tissue and serum from patients with severe heart failure (HF) undergoing placement of left ventricular assist devices and controls. Lipidomic analysis revealed increased total and very long–chain ceramides in myocardium and serum of patients with advanced HF. After unloading, these changes showed partial reversibility. Following myocardial infarction (MI), serine palmitoyl transferase (SPT), the rate-limiting enzyme of the de novo pathway of ceramide synthesis, and ceramides were found increased. Blockade of SPT by the specific inhibitor myriocin reduced ceramide accumulation in ischemic cardiomyopathy and decreased C16, C24:1, and C24 ceramides. SPT inhibition also reduced ventricular remodeling, fibrosis, and macrophage content following MI. Further, genetic deletion of the
Ruiping Ji, Hirokazu Akashi, Konstantinos Drosatos, Xianghai Liao, Hongfeng Jiang, Peter J. Kennel, Danielle L. Brunjes, Estibaliz Castillero, Xiaokan Zhang, Lily Y. Deng, Shunichi Homma, Isaac J. George, Hiroo Takayama, Yoshifumi Naka, Ira J. Goldberg, P. Christian Schulze
Mechanisms of atherogenesis have been studied extensively in genetically engineered mice with disturbed cholesterol metabolism such as those lacking either the LDL receptor (
Srinivas D. Sithu, Marina V. Malovichko, Krista A. Riggs, Nalinie S. Wickramasinghe, Millicent G. Winner, Abhinav Agarwal, Rihab E. Hamed-Berair, Anuradha Kalani, Daniel W. Riggs, Aruni Bhatnagar, Sanjay Srivastava
Fibrotic lung disease, most notably idiopathic pulmonary fibrosis (IPF), is thought to result from aberrant wound-healing responses to repetitive lung injury. Increased vascular permeability is a cardinal response to tissue injury, but whether it is mechanistically linked to lung fibrosis is unknown. We previously described a model in which exaggeration of vascular leak after lung injury shifts the outcome of wound-healing responses from normal repair to pathological fibrosis. Here we report that the fibrosis produced in this model is highly dependent on thrombin activity and its downstream signaling pathways. Direct thrombin inhibition with dabigatran significantly inhibited protease-activated receptor-1 (PAR1) activation, integrin αvβ6 induction, TGF-β activation, and the development of pulmonary fibrosis in this vascular leak–dependent model. We used a potentially novel imaging method — ultashort echo time (UTE) lung magnetic resonance imaging (MRI) with the gadolinium-based, fibrin-specific probe EP-2104R — to directly visualize fibrin accumulation in injured mouse lungs, and to correlate the antifibrotic effects of dabigatran with attenuation of fibrin deposition. We found that inhibition of the profibrotic effects of thrombin can be uncoupled from inhibition of hemostasis, as therapeutic anticoagulation with warfarin failed to downregulate the PAR1/αvβ6/TGF-β axis or significantly protect against fibrosis. These findings have direct and important clinical implications, given recent findings that warfarin treatment is not beneficial in IPF, and the clinical availability of direct thrombin inhibitors that our data suggest could benefit these patients.
Barry S. Shea, Clemens K. Probst, Patricia L. Brazee, Nicholas J. Rotile, Francesco Blasi, Paul H. Weinreb, Katharine E. Black, David E. Sosnovik, Elizabeth M. Van Cott, Shelia M. Violette, Peter Caravan, Andrew M. Tager
Motor dysfunction is a prominent and disabling feature of Huntington’s disease (HD), but the molecular mechanisms that dictate its onset and progression are unknown. The N-methyl-D-aspartate receptor 2A (NR2A) subunit regulates motor skill development and synaptic plasticity in medium spiny neurons (MSNs) of the striatum, cells that are most severely impacted by HD. Here, we document reduced NR2A receptor subunits on the dendritic membranes and at the synapses of MSNs in zQ175 mice that model HD. We identify that SorCS2, a vacuolar protein sorting 10 protein–domain (VPS10P-domain) receptor, interacts with VPS35, a core component of retromer, thereby regulating surface trafficking of NR2A in MSNs. In the zQ175 striatum, SorCS2 is markedly decreased in an age- and allele-dependent manner. Notably, SorCS2 selectively interacts with mutant huntingtin (mtHTT), but not WT huntingtin (wtHTT), and is mislocalized to perinuclear clusters in striatal neurons of human HD patients and zQ175 mice. Genetic deficiency of SorCS2 accelerates the onset and exacerbates the motor coordination deficit of zQ175 mice. Together, our results identify SorCS2 as an interacting protein of mtHTT and demonstrate that impaired SorCS2-mediated NR2A subunit trafficking to dendritic surface of MSNs is, to our knowledge, a novel mechanism contributing to motor coordination deficits of HD.
Qian Ma, Jianmin Yang, Teresa A. Milner, Jean-Paul G. Vonsattel, Mary Ellen Palko, Lino Tessarollo, Barbara L. Hempstead
During renal branching morphogenesis, ureteric bud tip cells (UBTC) serve as the progenitor epithelium for all cell types of the collecting duct. While the transcriptional circuitry of ureteric bud (UB) branching has been intensively studied, the transcriptional control of UBTC differentiation has been difficult to ascertain. This is partly due to limited knowledge of UBTC-specific transcription factors that mark the progenitor state. Here, we identify the transcription factor p63 (also known as TP63), a master regulator of basal stem cells in stratified epithelia, as a specific marker of mouse and human UBTC. Nuclear p63 marks Ret+ UBTC transiently and is silenced by the end of nephrogenesis. Lineage tracing revealed that a subset of UBTC expressing the ΔNp63 isoform (N-terminus truncated p63) is dedicated to generating cortical intercalated cells. Germline targeting of
Samir S. El-Dahr, Yuwen Li, Jiao Liu, Elleny Gutierrez, Kathleen S. Hering-Smith, Sabina Signoretti, Jean-Christophe Pignon, Satrajit Sinha, Zubaida Saifudeen
Despite expression of immunogenic polypeptides, tumors escape immune surveillance by engaging T cell checkpoint regulators and expanding Tregs, among other mechanisms. What orchestrates these controls is unknown. We report that free C3d, a fragment of the third component of complement, inside tumor cells — or associated with irradiated tumor cells and unattached to antigen — recruits, accelerates, and amplifies antitumor T cell responses, allowing immunity to reverse or even to prevent tumor growth. C3d enhances antitumor immunity independently of B cells, NK cells, or antibodies, but it does so by increasing tumor infiltrating CD8+ lymphocytes, by depleting Tregs, and by suppressing expression of programmed cell death protein 1 (PD-1) by T cells. These properties of C3d appear specific for the tumor and dependent on complement receptor 2, and they incur no obvious systemic toxicity. The heretofore unrecognized properties of free C3d suggest that protein might determine the effectiveness of immune surveillance and that increasing availability of the protein might prove advantageous in the treatment or prevention of cancer and premalignant conditions.
Jeffrey L. Platt, Inês Silva, Samuel J. Balin, Adam R. Lefferts, Evan Farkash, Ted M. Ross, Michael C. Carroll, Marilia Cascalho
Glaucoma is the second leading cause of blindness worldwide. Physicians often use surrogate endpoints to monitor the progression of glaucomatous neurodegeneration. These approaches are limited in their ability to quantify disease severity and progression due to inherent subjectivity, unreliability, and limitations of normative databases. Therefore, there is a critical need to identify specific molecular markers that predict or measure glaucomatous neurodegeneration. Here, we demonstrate that growth differentiation factor 15 (GDF15) is associated with retinal ganglion cell death.
Norimitsu Ban, Carla J. Siegfried, Jonathan B. Lin, Ying-Bo Shui, Julia Sein, Wolfgang Pita-Thomas, Abdoulaye Sene, Andrea Santeford, Mae Gordon, Rachel Lamb, Zhenyu Dong, Shannon C. Kelly, Valeria Cavalli, Jun Yoshino, Rajendra S. Apte
Combined pulmonary insufficiency (PI) and stenosis (PS) is a common long-term sequela after repair of many forms of congenital heart disease, causing progressive right ventricular (RV) dilation and failure. Little is known of the mechanisms underlying this combination of preload and afterload stressors. We developed a murine model of PI and PS (PI+PS) to identify clinically relevant pathways and biomarkers of disease progression. Diastolic dysfunction was induced (restrictive RV filling, elevated RV end-diastolic pressures) at 1 month after generation of PI+PS and progressed to systolic dysfunction (decreased RV shortening) by 3 months. RV fibrosis progressed from 1 month (4.4% ± 0.4%) to 3 months (9.2% ± 1%), along with TGF-β signaling and tissue expression of profibrotic miR-21. Although plasma miR-21 was upregulated with diastolic dysfunction, it was downregulated with the onset of systolic dysfunction), correlating with RV fibrosis. Plasma miR-21 in children with PI+PS followed a similar pattern. A model of combined RV volume and pressure overload recapitulates the evolution of RV failure unique to patients with prior RV outflow tract surgery. This progression was characterized by enhanced TGF-β and miR-21 signaling. miR-21 may serve as a plasma biomarker of RV failure, with decreased expression heralding the need for valve replacement.
Sushma Reddy, Dong-Qing Hu, Mingming Zhao, Eddie Blay Jr., Nefthi Sandeep, Sang-Ging Ong, Gwanghyun Jung, Kristina B. Kooiker, Michael Coronado, Giovanni Fajardo, Daniel Bernstein
Brown adipose tissue (BAT) is a central organ that acts to increase energy expenditure; its regulatory factors could be clinically useful in the treatment of obesity. Tetrahydrobiopterin (BH4) is an essential cofactor of tyrosine hydroxylase and nitric oxide synthase (NOS). Although BH4 regulates the known regulatory factors of BAT, such as noradrenaline (NA) and NO, participation of BH4 in BAT function remains unclear. In the present study, we investigate the role of BH4 in the regulation of BAT. Hph-1 mice, a mouse model of BH4 deficiency, exhibit obesity, adiposity, glucose intolerance, insulin resistance, and impaired BAT function. Impaired BAT function was ameliorated together with systemic metabolic disturbances by BAT transplantation from BH4-sufficient mice (control mice) into BH4-deficient mice, strongly suggesting that BH4-induced BAT has a critical role in the regulation of systemic energy metabolism. Both NA derived from the sympathetic nerve and NO derived from endothelial NOS in the blood vessels participate in the regulation of BH4. In addition, a direct effect of BH4 in the stimulation of brown adipocytes via NO is implicated. Taken together, BH4 activates BAT and regulates systemic energy metabolism; this suggests an approach for metabolic disorders, such as obesity and diabetes.
Yasuo Oguri, Yoshihito Fujita, Abulizi Abudukadier, Akiko Ohashi, Tsuyoshi Goto, Futoshi Furuya, Akio Obara, Toru Fukushima, Naomi Matsuo, Minji Kim, Masaya Hosokawa, Teruo Kawada, Hiroyuki Hasegawa, Nobuya Inagaki
Despite recent evidence of improved graft outcomes and safety, the high incidence of early acute cellular rejection with belatacept, a high-affinity CTLA4-Ig, has limited its use in clinical transplantation. Here we define how the incomplete control of endogenous donor-reactive memory T cells results in belatacept-resistant rejection in an experimental model of BALB/c.2W-OVA donor heart transplantation into C57BL/6 recipients presensitized to donor splenocytes. These sensitized mice harbored modestly elevated numbers of endogenous donor-specific memory T cells and alloantibodies compared with naive recipients. Continuous CTLA4-Ig treatment was unexpectedly efficacious at inhibiting endogenous graft-reactive T cell expansion but was unable to inhibit late CD4+ and CD8+ T cell infiltration into the allografts, and rejection was observed in 50% of recipients by day 35 after transplantation. When CTLA4-Ig was combined with the sphingosine 1-phosphate receptor-1 (S1PR1) functional antagonist FTY720, alloantibody production was inhibited and donor-specific IFN-γ–producing T cells were reduced to levels approaching nonsensitized tolerant recipients. Late T cell recruitment into the graft was also restrained, and graft survival improved with this combination therapy. These observations suggest that a rational strategy consisting of inhibiting memory T cell expansion and trafficking into the allograft with CTLA4-Ig and FTY720 can promote allograft survival in allosensitized recipients.
Stella H. Khiew, Jinghui Yang, James S. Young, Jianjun Chen, Qiang Wang, Dengping Yin, Vinh Vu, Michelle L. Miller, Roger Sciammas, Maria-Luisa Alegre, Anita S. Chong
Brateil Badal, Alexander Solovyov, Serena Di Cecilia, Joseph Minhow Chan, Li-Wei Chang, Ramiz Iqbal, Iraz T. Aydin, Geena S. Rajan, Chen Chen, Franco Abbate, Kshitij S. Arora, Antoine Tanne, Stephen B. Gruber, Timothy M. Johnson, Douglas R. Fullen, Leon Raskin, Robert Phelps, Nina Bhardwaj, Emily Bernstein, David T. Ting, Georg Brunner, Eric E. Schadt, Benjamin D. Greenbaum, Julide Tok Celebi
Pemphigus vulgaris (PV) is an epithelial blistering disease caused by autoantibodies to the desmosomal cadherin desmoglein 3 (DSG3). Glucocorticoids improve disease within days by increasing DSG3 gene transcription, although the mechanism for this observation remains unknown. Here, we show that DSG3 transcription in keratinocytes is regulated by Stat3. Treatment of primary human keratinocytes (PHKs) with hydrocortisone or rapamycin, but not the p38 MAPK inhibitor SB202190, significantly increases DSG3 mRNA and protein expression and correspondingly reduces phospho-S727 Stat3. Stat3 inhibition or shRNA-knockdown also significantly increases DSG3 mRNA and protein levels. Hydrocortisone- or rapamycin-treated PHKs demonstrate increased number and length of desmosomes by electron microscopy and are resistant to PV IgG–induced loss of cell adhesion, whereas constitutive activation of Stat3 in PHKs abrogates DSG3 upregulation and inhibits hydrocortisone and rapamycin’s therapeutic effects. Topical hydrocortisone, rapamycin, or Stat3 inhibitor XVIII prevents autoantibody-induced blistering in the PV passive transfer mouse model, correlating with increased epidermal DSG3 expression and decreased phospho-S727 Stat3. Our data indicate that glucocorticoids and rapamycin upregulate DSG3 transcription through inhibition of Stat3. These studies explain how glucocorticoids rapidly improve pemphigus and may also offer novel insights into the physiologic and pathophysiologic regulation of desmosomal cadherin expression in normal epidermis and epithelial carcinomas.
Xuming Mao, Michael Jeffrey T. Cho, Christoph T. Ellebrecht, Eric M. Mukherjee, Aimee S. Payne
Initial promising results with immune sera guided early human mAb approaches against Gram-negative sepsis to an LPS neutralization mechanism, but these efforts failed in human clinical trials. Emergence of multidrug resistance has renewed interest in pathogen-specific mAbs. We utilized a pair of antibodies targeting
Taylor S. Cohen, Mark Pelletier, Lily Cheng, Meghan E. Pennini, Jessica Bonnell, Romana Cvitkovic, Chew-shun Chang, Xiaodong Xiao, Elisabetta Cameroni, Davide Corti, Elena Semenova, Paul Warrener, Bret R. Sellman, JoAnn Suzich, Qun Wang, C. Kendall Stover
Unconjugated bilirubin (UCB), a product of heme oxidation, has known immunosuppressant properties but the molecular mechanisms, other than antioxidant effects, remain largely unexplored. We note that UCB modulates T helper type 17 (Th17) immune responses, in a manner dependent upon heightened expression of CD39 ectonucleotidase. UCB has protective effects in experimental colitis, where it enhances recovery after injury and preferentially boosts IL-10 production by colonic intraepithelial CD4+ cells. In vitro, UCB confers immunoregulatory properties on human control Th17 cells, as reflected by increased levels of FOXP3 and CD39 with heightened cellular suppressor ability. Upregulation of CD39 by Th17 cells is dependent upon ligation of the aryl hydrocarbon receptor (AHR) by UCB. Genetic deletion of CD39, as in
Maria Serena Longhi, Marta Vuerich, Alireza Kalbasi, Jessica E. Kenison, Ada Yeste, Eva Csizmadia, Byron Vaughn, Linda Feldbrugge, Shuji Mitsuhashi, Barbara Wegiel, Leo Otterbein, Alan Moss, Francisco J. Quintana, Simon C. Robson
Here, we report the isolation of broadly neutralizing mAbs (bNAbs) from persons with broadly neutralizing serum who spontaneously cleared hepatitis C virus (HCV) infection. We found that bNAbs from two donors bound the same epitope and were encoded by the same germline heavy chain variable gene segment. Remarkably, these bNAbs were encoded by antibody variable genes with sparse somatic mutations. For one of the most potent bNAbs, these somatic mutations were critical for antibody neutralizing breadth and for binding to autologous envelope variants circulating late in infection. However, somatic mutations were not necessary for binding of the bNAb unmutated ancestor to envelope proteins of early autologous transmitted/founder viruses. This study identifies a public B cell clonotype favoring early recognition of a conserved HCV epitope, proving that anti-HCV bNAbs can achieve substantial neutralizing breadth with relatively few somatic mutations, and identifies HCV envelope variants that favored selection and maturation of an anti-HCV bNAb in vivo. These data provide insight into the molecular mechanisms of immune-mediated clearance of HCV infection and present a roadmap to guide development of a vaccine capable of stimulating anti-HCV bNAbs with a physiologic number of somatic mutations characteristic of vaccine responses.
Justin R. Bailey, Andrew I. Flyak, Valerie J. Cohen, Hui Li, Lisa N. Wasilewski, Anna E. Snider, Shuyi Wang, Gerald H. Learn, Nurgun Kose, Leah Loerinc, Rebecca Lampley, Andrea L. Cox, Jennifer M. Pfaff, Benjamin J. Doranz, George M. Shaw, Stuart C. Ray, James E. Crowe Jr.
Contact hypersensitivity (CHS) is a common skin disease induced by epicutaneous sensitization to haptens. Conflicting results have been obtained regarding pathogenic versus protective roles of mast cells (MCs) in CHS, and this has been attributed in part to the limitations of certain models for studying MC functions in vivo. Here we describe a fluorescent imaging approach that enables in vivo selective labeling and tracking of MC secretory granules by real-time intravital 2-photon microscopy in living mice, and permits the identification of such MCs as a potential source of cytokines in different disease models. We show using this method that dermal MCs release their granules progressively into the surrounding microenvironment, but also represent an initial source of the antiinflammatory cytokine IL-10, during the early phase of severe CHS reactions. Finally, using 3 different types of MC-deficient mice, as well as mice in which IL-10 is ablated specifically in MCs, we show that IL-10 production by MCs can significantly limit the inflammation and tissue pathology observed in severe CHS reactions.
Laurent L. Reber, Riccardo Sibilano, Philipp Starkl, Axel Roers, Michele A. Grimbaldeston, Mindy Tsai, Nicolas Gaudenzio, Stephen J. Galli
The discovery of metabolite-phenotype associations may highlight candidate biomarkers and metabolic pathways altered in disease states. We sought to identify novel metabolites associated with obesity and one of its major complications, nonalcoholic fatty liver disease (NAFLD), using a liquid chromatography–tandem mass spectrometry method. In 997 individuals in Framingham Heart Study Generation 3 (FHS Gen 3), we identified an association between anandamide (AEA) and BMI. Further examination revealed that AEA was associated with radiographic hepatic steatosis. In a histologically defined NAFLD cohort, AEA was associated with NAFLD severity, the presence of nonalcoholic steatohepatitis, and fibrosis. These data highlight AEA as a marker linking cardiometabolic disease and NAFLD severity.
W. Taylor Kimberly, John F. O’Sullivan, Anjali K. Nath, Michelle Keyes, Xu Shi, Martin G. Larson, Qiong Yang, Michelle T. Long, Ramachandran Vasan, Randall T. Peterson, Thomas J. Wang, Kathleen E. Corey, Robert E. Gerszten
Lupus nephritis is a leading cause of mortality among systemic lupus erythematosus (SLE) patients, and its heterogeneous nature poses a significant challenge to the development of effective diagnostics and treatments. Single cell RNA sequencing (scRNA-seq) offers a potential solution to dissect the heterogeneity of the disease and enables the study of similar cell types distant from the site of renal injury to identify novel biomarkers. We applied scRNA-seq to human renal and skin biopsy tissues and demonstrated that scRNA-seq can be performed on samples obtained during routine care. Chronicity index, IgG deposition, and quantity of proteinuria correlated with a transcriptomic-based score composed of IFN-inducible genes in renal tubular cells. Furthermore, analysis of cumulative expression profiles of single cell keratinocytes dissociated from nonlesional, non–sun-exposed skin of patients with lupus nephritis also revealed upregulation of IFN-inducible genes compared with keratinocytes isolated from healthy controls. This indicates the possible use of scRNA-seq analysis of skin biopsies as a biomarker of renal disease. These data support the potential utility of scRNA-seq to provide new insights into the pathogenesis of lupus nephritis and pave the way for exploiting a readily accessible tissue to reflect injury in the kidney.
Evan Der, Saritha Ranabothu, Hemant Suryawanshi, Kemal M. Akat, Robert Clancy, Pavel Morozov, Manjunath Kustagi, Mareike Czuppa, Peter Izmirly, H. Michael Belmont, Tao Wang, Nicole Jordan, Nicole Bornkamp, Janet Nwaukoni, July Martinez, Beatrice Goilav, Jill P. Buyon, Thomas Tuschl, Chaim Putterman
Duchenne muscular dystrophy (DMD) is caused by dystrophin deficiency resulting in progressive muscle weakness and fibrotic scarring. Muscle fibrosis impairs blood flow, hampering muscle repair and regeneration. Irrespective of the success of gene restoration, functional improvement is limited without reducing fibrosis. The levels of miR-29c, a known regulator of collagen, are reduced in DMD. Our goal is to develop translational, antifibrotic therapy by overexpressing miR-29c. We injected the gastrocnemius muscle with either self-complementary AAV.CMV.miR-29c or single-stranded AAV.MCK.micro-dystrophin alone or in combination in the
Kristin N. Heller, Joshua T. Mendell, Jerry R. Mendell, Louise R. Rodino-Klapac
Development of antiviral therapy against acute viral diseases, such as dengue virus (DENV), suffers from the narrow window of viral load detection in serum during onset and clearance of infection and fever. We explored a biomarker approach using 18F-fluorodeoxyglucose (18F-FDG) PET in established mouse models for primary and antibody-dependent enhancement infection with DENV. 18F-FDG uptake was most prominent in the intestines and correlated with increased virus load and proinflammatory cytokines. Furthermore, a significant temporal trend in 18F-FDG uptake was seen in intestines and selected tissues over the time course of infection. Notably, 18F-FDG uptake and visualization by PET robustly differentiated treatment-naive groups from drug-treated groups as well as nonlethal from lethal infections with a clinical strain of DENV2. Thus, 18F-FDG may serve as a novel DENV infection–associated inflammation biomarker for assessing treatment response during therapeutic intervention trials.
Ann-Marie Chacko, Satoru Watanabe, Keira J. Herr, Shirin Kalimuddin, Jing Yang Tham, Joanne Ong, Marie Reolo, Raymond M.F. Serrano, Yin Bun Cheung, Jenny G.H. Low, Subhash G. Vasudevan
Non–transferrin-bound iron (NTBI) and free hemoglobin (Hb) accumulate in circulation following stored RBC transfusions. This study investigated transfusion, vascular disease, and mortality in guinea pigs after stored RBC transfusion alone and following cotransfusion with apo-transferrin (apo-Tf) and haptoglobin (Hp). The effects of RBC exchange transfusion dose (1, 3, and 9 units), storage period (14 days), and mortality were evaluated in guinea pigs with a vascular disease phenotype. Seven-day mortality and the interaction between iron and Hb as cocontributors to adverse outcome were studied. Concentrations of iron and free Hb were greatest after transfusion with 9 units of stored RBCs compared with fresh RBCs or stored RBCs at 1- and 3-unit volumes. Nine units of stored RBCs led to mortality in vascular diseased animals, but not normal animals. One and 3 units of stored RBCs did not cause a mortality effect, suggesting the concomitant relevance of NTBI and Hb on outcome. Cotransfusion with apo-Tf or Hp restored survival to 100% following 9-unit RBC transfusions in vascular diseased animals. Our data suggest that increases in plasma NTBI and Hb contribute to vascular disease–associated mortality through iron-enhanced Hb oxidation and enhanced tissue injury.
Jin Hyen Baek, Ayla Yalamanoglu, Yamei Gao, Ricardo Guenster, Donat R. Spahn, Dominik J. Schaer, Paul W. Buehler