Publications by authors named "Colin C Anderson"

58 Publications

Trisomy 21 results in modest impacts on mitochondrial function and central carbon metabolism.

Free Radic Biol Med 2021 Jun 12;172:201-212. Epub 2021 Jun 12.

Department of Pharmaceutical Sciences, Skaggs School of Pharmacy and Pharmaceutical Sciences, USA; Linda Crnic Institute for Down Syndrome, School of Medicine, University of Colorado, Aurora, CO, USA. Electronic address:

Down syndrome (DS) is the most common genetic cause of intellectual disability. Mechanistically, oxidative stress and mitochondrial dysfunction are reported to be etiological factors for many of the DS-related comorbidities and have previously been reported in a number of in vitro and in vivo models of DS. The purpose of this study was to test for the presence of mitochondrial dysfunction in fibroblast cells obtained via skin biopsy from individuals with DS, and to assess the impact of trisomy 21 on central carbon metabolism. Using extracellular flux assays in matched dermal fibroblasts from euploid and DS individuals, we found that basal mitochondrial dysfunction is quite mild. Stressing the cells with a cocktail of mitochondrial stressors revealed a significant mitochondrial deficit in DS cells compared to euploid controls. Evaluation of extracellular acidification rate did not reveal a baseline abnormality in glycolysis; however, metabolomic assessments utilizing isotopically labeled glucose and glutamine revealed altered central carbon metabolism in DS cells. Specifically, we observed greater glucose dependency, uptake and flux into the oxidative phase of the pentose phosphate pathway in DS fibroblasts. Furthermore, using induced pluripotent stem cells (iPSC) we found that mitochondrial function in DS iPSCs was similar to the previously published studies employing fetal cells. Together, these data indicate that aberrant central carbon metabolism is a candidate mechanism for stress-related mitochondrial dysfunction in DS.
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http://dx.doi.org/10.1016/j.freeradbiomed.2021.06.003DOI Listing
June 2021

Tackling cancer cell dormancy: Insights from immune models, and transplantation.

Semin Cancer Biol 2021 Feb 11. Epub 2021 Feb 11.

Departments of Surgery and Medical Microbiology and Immunology, Alberta Diabetes Institute, Alberta Transplant Institute, University of Alberta, Edmonton, Alberta, Canada. Electronic address:

Disseminated non-dividing (dormant) cancer cells as well as those in equilibrium with the immune response remain the major challenge for successful treatment of cancer. The equilibrium between disseminated dormant cancer cells and the immune system is reminiscent of states that can occur during infection or allogeneic tissue and cell transplantation. We discuss here the major competing models of how the immune system achieves a self nonself discrimination (pathogen/danger patterns, quorum, and coinhibition/tuning models), and suggest that taking advantage of a combination of the proposed mechanisms in each model may lead to increased efficacy in tackling cancer cell dormancy.
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http://dx.doi.org/10.1016/j.semcancer.2021.02.002DOI Listing
February 2021

CD5 levels reveal distinct basal T-cell receptor signals in T cells from non-obese diabetic mice.

Immunol Cell Biol 2021 Jul 8;99(6):656-667. Epub 2021 Mar 8.

Immunology-Oncology Unit, Maisonneuve-Rosemont Hospital Research Center, Montréal, Québec, Canada.

Type 1 diabetes in non-obese diabetic (NOD) mice occurs when autoreactive T cells eliminate insulin producing pancreatic β cells. While extensively studied in T-cell receptor (TCR) transgenic mice, the contribution of alterations in thymic selection to the polyclonal T-cell pool in NOD mice is not yet resolved. The magnitude of signals downstream of TCR engagement with self-peptide directs the development of a functional T-cell pool, in part by ensuring tolerance to self. TCR interactions with self-peptide are also necessary for T-cell homeostasis in the peripheral lymphoid organs. To identify differences in TCR signal strength that accompany thymic selection and peripheral T-cell maintenance, we compared CD5 levels, a marker of basal TCR signal strength, on immature and mature T cells from autoimmune diabetes-prone NOD and -resistant B6 mice. The data suggest that there is no preferential selection of NOD thymocytes that perceive stronger TCR signals from self-peptide engagement. Instead, NOD mice have an MHC-dependent increase in CD4 thymocytes and mature T cells that express lower levels of CD5. In contrast, T cell-intrinsic mechanisms lead to higher levels of CD5 on peripheral CD8 T cells from NOD relative to B6 mice, suggesting that peripheral CD8 T cells with higher basal TCR signals may have survival advantages in NOD mice. These differences in the T-cell pool in NOD mice may contribute to the development or progression of autoimmune diabetes.
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http://dx.doi.org/10.1111/imcb.12443DOI Listing
July 2021

Trisomy 21 impairs PGE2 production in dermal fibroblasts.

Prostaglandins Other Lipid Mediat 2021 Apr 5;153:106524. Epub 2021 Jan 5.

Department of Pharmaceutical Sciences, Skaggs School of Pharmacy and Pharmaceutical Sciences, University of Colorado, USA; Linda Crnic Institute for Down Syndrome, Aurora, Colorado, USA. Electronic address:

The triplication of human chromosome 21 results in Down syndrome (DS), the most common genetic form of intellectual disability. This aneuploid condition also results in an enhanced risk of a spectrum of comorbid conditions, such as leukemia, early onset Alzheimer's disease, and diabetes. Individuals with DS also display an increased incidence of wound healing complications and resistance to solid tumor development. Due to this unique phenotype and the involvement of eicosanoids in key comorbidities like poor healing and tumor development, we hypothesized that cells from DS individuals would display altered eicosanoid production. Using age- and sex-matched dermal fibroblasts we interrogated this hypothesis. Briefly, assessment of over 90 metabolites derived from cyclooxygenase (COX), lipoxygenase (LOX), and cytochrome p450 systems revealed a possible deficiency in the COX system. Basal gene expression and Western blotting experiments showed significantly decreased gene expression of COX1 and 2, and COX2 protein abundance in DS fibroblasts compared to euploid controls. Further, using two different stressors, scratch wound or LPS, we found that DS fibroblasts could not upregulate COX2 abundance and prostaglandin E2 production. Together, these findings show that dermal fibroblasts from DS individuals have a deficient COX2 response, which may contribute to wound healing complications and tumor resistance in DS.
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http://dx.doi.org/10.1016/j.prostaglandins.2020.106524DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7965340PMC
April 2021

Maneb alters central carbon metabolism and thiol redox status in a toxicant model of Parkinson's disease.

Free Radic Biol Med 2021 01 3;162:65-76. Epub 2020 Dec 3.

Department of Pharmaceutical Sciences, Skaggs School of Pharmacy and Pharmaceutical Sciences, Aurora, CO, 80045, USA. Electronic address:

The dithiocarbamate fungicide maneb (MB) has attracted interest due to increasing concern of the negative health effects of pesticides, as well as its association with Parkinson's disease (PD). Our laboratory has previously reported distinct phenotypic changes of neuroblastoma cells exposed to acute, sub-toxic levels of MB, including decreased mitochondrial respiration, altered lactate dynamics, and metabolic stress. In this study, we aimed to further define the specific molecular mechanisms of MB toxicity through the comparison of several thiol-containing compounds and their effects on cellular energy metabolism and thiol redox nodes. Extracellular flux analyses and stable isotope labeled tracer metabolomics were employed to evaluate alterations in energy metabolism of SK-N-AS human neuroblastoma cells after acute exposure of an array of compounds, including dithiocarbamates (maneb, nabam, zineb) and other thiol-containing small molecules (glutathione, N-acetylcysteine). These studies revealed MB and its methylated form (MeDTC) as unique toxicants with significant alterations to mitochondrial respiration, proliferation, and glycolysis. We observed MB to significantly impact cellular thiol redox status by oxidizing cellular glutathione and altering the thiol redox status of peroxiredoxin 3 (Prx3, mitochondrial) after acute exposure. Redox Western blotting revealed a MB-specific modification of cellular Prx3, strengthening the argument that MB can preferentially target mitochondrial enzymes containing reactive cysteine thiols. Further, stable isotope tracer metabolomics confirmed our energetics assessments, and demonstrated that MB exposure results in acute derangement of central carbon metabolism. Specifically, we observed shunting of cellular glucose into the pentose-phosphate pathway and reduction of TCA intermediates derived from glucose and glutamine. Also, we report novel lactate utilization for TCA enrichment and glutathione synthesis after MB exposure. In summary, our results further confirm that MB exerts its toxic effects via thiol modification, and significantly transforms central carbon metabolism.
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http://dx.doi.org/10.1016/j.freeradbiomed.2020.11.028DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7889696PMC
January 2021

Anti-CD52 blocks EAE independent of PD-1 signals and promotes repopulation dominated by double-negative T cells and newly generated T and B cells.

Eur J Immunol 2020 09 27;50(9):1362-1373. Epub 2020 May 27.

Department of Surgery, University of Alberta, Edmonton, AB, Canada.

Lymphocyte depletion using anti-CD52 antibody effectively reduces relapses of multiple sclerosis (MS). To begin to understand what mechanisms might control this outcome, we examined the effect of a murine-CD52-specific mAb on the depletion and repopulation of immune cells in mice with experimental autoimmune encephalomyelitis (EAE), a model of MS. We tested whether the tolerance-promoting receptor programmed cell death protein-1 (PD-1) is required for disease remission post anti-CD52, and found that PD-1-deficient mice with a more severe EAE were nevertheless effectively treated with anti-CD52. Anti-CD52 increased the proportions of newly generated T cells and double-negative (DN) T cells while reducing newly generated B cells; the latter effect being associated with a higher expression of CD52 by these cells. In the longer term, anti-CD52 caused substantial increases in the proportion of newly generated lymphocytes and DN T cells in mice with EAE. Thus, the rapid repopulation of lymphocytes from central lymphoid organs post anti-CD52 may limit further disease. Furthermore, these data identify DN T cells, a subset with immunoregulatory potential, as a significant hyperrepopulating subset following CD52-mediated depletion.
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http://dx.doi.org/10.1002/eji.201948288DOI Listing
September 2020

Time-dependent simvastatin administration enhances doxorubicin toxicity in neuroblastoma.

Toxicol Rep 2020 22;7:520-528. Epub 2020 Apr 22.

Department of Pharmaceutical Sciences, Skaggs School of Pharmacy and Pharmaceutical Sciences, University of Colorado, Aurora, CO 80045, United States.

Statins have a primary indication for the reduction and management of hypercholesterolemia; however, evidence shows that statins have the ability to increase the toxicity of chemotherapeutics within cancer cells by inducing anti-proliferative, anti-metastatic, and anti-angiogenic effects. More recently, lipophilic statins have shown complex interaction with energy metabolism, specifically acute mitochondrial dysfunction and delayed inhibition of glycolysis. With the goal to demonstrate that statin-mediated enhancement of chemotherapeutics is time-dependent, we hypothesized that the lipophilic statin simvastatin, in conjunction with variable co-exposure of doxorubicin or cisplatin, will enhance the toxicity of these drugs in neuroblastoma. Utilizing human SK-N-AS neuroblastoma cells, we assessed cell proliferation, necrosis, caspase activation, and overall apoptosis of these cells. After determining the toxicity of simvastatin at 48 h post-treatment, 10μM was chosen as the intervention concentration. We found that significant cell death resulted from 1.0μM dose of doxorubicin with 24 h pre-treatment of simvastatin. On the other hand, simvastatin enhancement of cisplatin toxicity was only observed in the co-exposure model. As doxorubicin has strict dosage limits due to its primary off-target toxicity in cardiac muscle, we further compared the effects of this drug combination on rat H9C2 cardiomyoblasts. We found that simvastatin did not enhance doxorubicin toxicity in this cell line. We conclude that simvastatin provides time-dependent sensitization of neuroblastoma cells to doxorubicin toxicity, and our results provide strong argument for the consideration of simvastatin as an adjuvant in doxorubicin-based chemotherapy programs.
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http://dx.doi.org/10.1016/j.toxrep.2020.03.007DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7184108PMC
April 2020

On T cell development, T cell signals, T cell specificity and sensitivity, and the autoimmunity facilitated by lymphopenia.

Scand J Immunol 2020 Jun 7;91(6):e12888. Epub 2020 May 7.

Department of Surgery, Alberta Diabetes Institute, Alberta Transplant Institute, University of Alberta, Edmonton, AB, Canada.

We propose a framework to explain how T cells achieve specificity and sensitivity, how the affinity of the TcR peptide/MHC interaction controls positive and negative thymic selection and mature T cell survival, and whether antigen-dependent activation and inactivation takes place. Two distinct types of signalling can lead to mature T cell multiplication. One requires the TcR to recognize with a certain affinity an antigen-derived peptide, an agonist peptide, bound to an MHC molecule. The other, the tonic signal, leads to naïve T cell survival and modest proliferation if the T cell successfully competes for endogenous, self-peptide/MHC ligands, involving lower affinity TCR/ligand interactions. Many suggest lymphopenia contributes to autoimmunity by increasing the strength of TcR-tonic signalling, and so activation of anti-self T cells. We suggest T cell activation requires antigen-mediated cooperation between T cells. Increased tonic signalling under lymphopenic conditions facilitates T cell proliferation and so antigen-dependent cooperation and activation of anti-self T cells.
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http://dx.doi.org/10.1111/sji.12888DOI Listing
June 2020

Desensitization using imlifidase and EndoS enables chimerism induction in allosensitized recipient mice.

Am J Transplant 2020 09 7;20(9):2356-2365. Epub 2020 Apr 7.

Department of Surgery, University of Alberta, Edmonton, Alberta, Canada.

Mixed hematopoietic chimerism induction as a way to foster tolerance to donor organs in recipients who have been sensitized to donor antigens is challenging. Donor-specific antibodies (DSA) are a dominant barrier toward successful donor bone marrow engraftment. Although desensitization methods are routinely used in recipients with allosensitization for allogeneic bone marrow transplantation, engraftment is frequently unsuccessful. To overcome the barrier of prior sensitization we tested enzymatic desensitization of donor-specific IgG using imlifidase and endoglycosidase of Streptococcus pyogenes (EndoS), which both partially block the function of DSA in mice, as a novel approach to improve murine bone marrow engraftment in primed hosts. We found that EndoS was capable of inhibiting antibody-mediated killing of donor cells in vivo. Furthermore, the effect of EndoS depended on the titer of DSA and the genetic background of the recipients. In combination with imlifidase, EndoS improved the survival of donor bone marrow cells. Together with cyclophosphamide, bortezomib, T cell depletion, and nonlethal irradiation, imlifidase in combination with EndoS allowed allogeneic bone marrow engraftment in sensitized recipients. We conclude that enzymatic inactivation of DSA, using the combination of imlifidase and EndoS, can be used for inducing donor hematopoietic chimerism in allosensitized recipient mice in combination with other desensitization strategies.
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http://dx.doi.org/10.1111/ajt.15851DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7496317PMC
September 2020

Significant association between tumor mutational burden and immune-related adverse events during immune checkpoint inhibition therapies.

Cancer Immunol Immunother 2020 May 9;69(5):683-687. Epub 2020 Mar 9.

Departments of Surgery and Medical Microbiology and Immunology, Alberta Diabetes Institute, Alberta Transplant Institute, University of Alberta, Edmonton, AB, T6G 2E1, Canada.

More than 2000 immuno-oncology agents are being tested or are in use as a result of the cancer immunotherapy revolution. Manipulation of co-inhibitory receptors has achieved tumor eradication in a minority of patients, but widespread immune-related adverse events (irAEs) compromised tolerance to healthy self-tissues in the majority. We have proposed that a major mechanism of irAEs is similar to a graft-versus-malignancy effect of graft-versus-host disease. To verify our hypothesis, we retrieved post-marketing data of adverse events from the U.S. Food and Drug Administration Adverse Event Reporting System. A significant positive correlation was revealed in 7677 patients between the reporting odds ratio of irAEs during immune checkpoint inhibitor therapy and the corresponding tumor mutational burden across 19 cancer types. These results can be interpreted to mean that the ICI drugs unleashed T cells against "altered-self," self, and tumors resulting in better overall survival.
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http://dx.doi.org/10.1007/s00262-020-02543-6DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7183506PMC
May 2020

Simvastatin Induces Delayed Apoptosis Through Disruption of Glycolysis and Mitochondrial Impairment in Neuroblastoma Cells.

Clin Transl Sci 2020 05 6;13(3):563-572. Epub 2020 Feb 6.

Department of Pharmaceutical Sciences, Skaggs School of Pharmacy and Pharmaceutical Sciences, University of Colorado, Aurora, Colorado, USA.

Simvastatin, a commonly used cholesterol-lowering drug, inhibits the mevalonate pathway involved in the synthesis of the mitochondrial electron carrier coenzyme Q10 (CoQ10), as well as other bioenergetics substrates. The purpose of this study was to investigate simvastatin exposure on mitochondrial respiration, metabolic fuel preferences, and glucose utilization. We hypothesized that simvastatin at a noncytotoxic dose will impair energy metabolism in human neuroblastoma cells. SK-N-AS cells were exposed at acute and chronic time points and evaluated in a Seahorse XF analyzer, revealing decreased mitochondrial and glycolytic parameters. Flow cytometry showed a significant induction of apoptosis in simvastatin-treated cells at 48 hours. Finally, multiple techniques were used to show that simvastatin-mediated impairment of bioenergetics is more complex than CoQ10 depletion or hampered glucose uptake. Therefore, the data reported here represent a biphasic hit to mitochondria followed by reduction in glucose and glutamine metabolism in neuroblastoma; adding mechanism to potential pleotropic effects of statins.
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http://dx.doi.org/10.1111/cts.12740DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7214657PMC
May 2020

Best practices for enhancing surgical research: a perspective from the Canadian Association of Chairs of Surgical Research

Can J Surg 2019 12;62(6):488-498

From the Department of Surgery, Schulich School of Medicine & Dentistry, Western University, London, Ont. (Sener); the Department of Surgery, University of Alberta, Edmonton, Alta. (Anderson); the Department of Surgery, Université Laval, Québec, Que. (Auger,Lacombe); the Department of Surgery, McGill University, Montreal, Que. (Barralet); the Department of Surgery, University of Calgary, Calgary, Alta. (Brindle); the Department of Surgery, University of Saskatchewan, Saskatoon, Sask. (Cayabyab); the Department of Surgery, University of Toronto, Toronto, Ont. (Fehlings); the Department of Surgery, Montreal Heart Institute, Université de Montréal, Montreal, Que. (Perrault); the Department of Surgery, Université de Sherbrooke, Sherbrooke, Que. (Sabbagh); the Department of Surgery, University of Ottawa, Ottawa, Ont. (Seely); the Department of Surgery, Queen’s University, Kingston, Ont. (Wallace); the Department of Surgery, Dalhousie University, Halifax, NS (Ellsmere); and the Department of Surgery, University of Manitoba, Winnipeg, Man. (Keijzer).

Summary: The Canadian Association of Chairs of Surgical Research was created in 2014, with representation from every departmental surgical research committee across Canada, to establish Canadian surgical research as a beacon for health care innovation and to propose solutions for the daily challenges facing surgeon-researchers. Our key mandate has been to identify challenges for surgeons and scientists performing research to prevent further erosion of this vital area of activity that benefits patients, health care service providers and Canadian society. This article outlines the findings of a nationwide survey sent to all members of departments of surgery across Canada, seeking input on current threats and potential solutions. The results suggest that surgical research in Canada is experiencing a decline in funding and an increase in challenges affecting research productivity of academic surgeons, such as pressures to be clinically active, unpredictable surgical schedules, growing administrative demands, and increasing complexity of patient populations. Although surgeons are productive in their research endeavours, institutional changes and sharing of best practices are needed to ensure sustainable growth of research programs.
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http://dx.doi.org/10.1503/cjs.012619DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6877375PMC
December 2019

Non-enzymatic Lysine Lactoylation of Glycolytic Enzymes.

Cell Chem Biol 2020 02 22;27(2):206-213.e6. Epub 2019 Nov 22.

Department of Pharmacology and Toxicology, College of Pharmacy, University of Arizona, Tucson, AZ 85721, USA. Electronic address:

Post-translational modifications (PTMs) regulate enzyme structure and function to expand the functional proteome. Many of these PTMs are derived from cellular metabolites and serve as feedback and feedforward mechanisms of regulation. We have identified a PTM that is derived from the glycolytic by-product, methylglyoxal. This reactive metabolite is rapidly conjugated to glutathione via glyoxalase 1, generating lactoylglutathione (LGSH). LGSH is hydrolyzed by glyoxalase 2 (GLO2), cycling glutathione and generating D-lactate. We have identified the non-enzymatic acyl transfer of the lactate moiety from LGSH to protein Lys residues, generating a "LactoylLys" modification on proteins. GLO2 knockout cells have elevated LGSH and a consequent marked increase in LactoylLys. Using an alkyne-tagged methylglyoxal analog, we show that these modifications are enriched on glycolytic enzymes and regulate glycolysis. Collectively, these data suggest a previously unexplored feedback mechanism that may serve to regulate glycolytic flux under hyperglycemic or Warburg-like conditions.
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http://dx.doi.org/10.1016/j.chembiol.2019.11.005DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7395678PMC
February 2020

Apelin directs endothelial cell differentiation and vascular repair following immune-mediated injury.

J Clin Invest 2020 01;130(1):94-107

Department of Medicine.

Sustained, indolent immune injury of the vasculature of a heart transplant limits long-term graft and recipient survival. This injury is mitigated by a poorly characterized, maladaptive repair response. Vascular endothelial cells respond to proangiogenic cues in the embryo by differentiation to specialized phenotypes, associated with expression of apelin. In the adult, the role of developmental proangiogenic cues in repair of the established vasculature is largely unknown. We found that human and minor histocompatibility-mismatched donor mouse heart allografts with alloimmune-mediated vasculopathy upregulated expression of apelin in arteries and myocardial microvessels. In vivo, loss of donor heart expression of apelin facilitated graft immune cell infiltration, blunted vascular repair, and worsened occlusive vasculopathy in mice. In vitro, an apelin receptor agonist analog elicited endothelial nitric oxide synthase activation to promote endothelial monolayer wound repair and reduce immune cell adhesion. Thus, apelin acted as an autocrine growth cue to sustain vascular repair and mitigate the effects of immune injury. Treatment with an apelin receptor agonist after vasculopathy was established markedly reduced progression of arterial occlusion in mice. Together, these initial data identify proangiogenic apelin as a key mediator of coronary vascular repair and a pharmacotherapeutic target for immune-mediated injury of the coronary vasculature.
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http://dx.doi.org/10.1172/JCI128469DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6934203PMC
January 2020

SNARE proteins rescue impaired autophagic flux in Down syndrome.

PLoS One 2019 12;14(11):e0223254. Epub 2019 Nov 12.

Department of Pharmaceutical Sciences, Skaggs School of Pharmacy and Pharmaceutical Sciences, University of Colorado, Aurora, CO, United States of America.

Down syndrome (DS) is a chromosomal disorder caused by trisomy of chromosome 21 (Ts21). Unbalanced karyotypes can lead to dysfunction of the proteostasis network (PN) and disrupted proteostasis is mechanistically associated with multiple DS comorbidities. Autophagy is a critical component of the PN that has not previously been investigated in DS. Based on our previous observations of PN disruption in DS, we investigated possible dysfunction of the autophagic machinery in human DS fibroblasts and other DS cell models. Following induction of autophagy by serum starvation, DS fibroblasts displayed impaired autophagic flux indicated by autophagolysosome accumulation and elevated p62, NBR1, and LC3-II abundance, compared to age- and sex-matched, euploid (CTL) fibroblasts. While lysosomal physiology was unaffected in both groups after serum starvation, we observed decreased basal abundance of the Soluble N-ethylmaleimide-sensitive-factor Attachment protein Receptor (SNARE) family members syntaxin 17 (STX17) and Vesicle Associated Membrane Protein 8 (VAMP8) indicating that decreased autophagic flux in DS is due at least in part to a possible impairment of autophagosome-lysosome fusion. This conclusion was further supported by the observation that over-expression of either STX17 or VAMP8 in DS fibroblasts restored autophagic degradation and reversed p62 accumulation. Collectively, our results indicate that impaired autophagic clearance is a characteristic of DS cells that can be reversed by enhancement of SNARE protein expression and provides further evidence that PN disruption represents a candidate mechanism for multiple aspects of pathogenesis in DS and a possible future target for therapeutic intervention.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0223254PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6850524PMC
March 2020

Toxicant-mediated redox control of proteostasis in neurodegeneration.

Curr Opin Toxicol 2019 Feb 28;13:22-34. Epub 2018 Dec 28.

Department of Pharmaceutical Sciences, Skaggs School of Pharmacy and Pharmaceutical Sciences, University of Colorado Anschutz Medical Campus, Aurora, CO 80045.

Disruption in redox signaling and control of cellular processes has emerged as a key player in many pathologies including neurodegeneration. As protein aggregations are a common hallmark of several neuronal pathologies, a firm understanding of the interplay between redox signaling, oxidative and free radical stress, and proteinopathies is required to sort out the complex mechanisms in these diseases. Fortunately, models of toxicant-induced neurodegeneration can be utilized to evaluate and report mechanistic alterations in the proteostasis network (PN). The epidemiological links between environmental toxicants and neurological disease gives further credence into characterizing the toxicant-mediated PN disruptions observed in these conditions. Reviewed here are examples of mechanistic interaction between oxidative or free radical stress and PN alterations. Additionally, investigations into toxicant-mediated PN disruptions, specifically focusing on environmental metals and pesticides, are discussed. Finally, we emphasize the need to distinguish whether the presence of protein aggregations are contributory to phenotypes related to neurodegeneration, or if they are a byproduct of PN deficiencies.
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http://dx.doi.org/10.1016/j.cotox.2018.12.007DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6785977PMC
February 2019

Exploiting autoimmunity unleashed by low-dose immune checkpoint blockade to treat advanced cancer.

Scand J Immunol 2019 Dec 7;90(6):e12821. Epub 2019 Oct 7.

Departments of Surgery and Medical Microbiology & Immunology, Alberta Diabetes Institute, Alberta Transplant Institute, University of Alberta, Edmonton, Alberta, Canada.

As a result of the cancer immunotherapy revolution, more than 2000 immuno-oncology agents are currently being tested or are in use to improve responses. Not unexpectedly, the 2018 Nobel Prize in Physiology or Medicine was awarded to James P. Allison and Tasuku Honjo for their development of cancer therapy by the blockade of co-inhibitory signals. Unfortunately, manipulation of the co-inhibitory receptors has also resulted in a safety issue: widespread iatrogenic immune-related adverse events (irAEs). Autoimmunity is emerging as the nemesis of immunotherapy. Originally, it was assumed that CTLA-4 blockade selectively targets T cells relevant to the antitumour immune response. However, an uncontrolled pan T cell activation was induced compromising tolerance to healthy self-tissues. The irAEs are very similar to that of a chronic graft-versus-host-disease (GVHD) reaction following allogeneic bone marrow transplantation (BMT). We hypothesized that ipilimumab induced a graft-versus-malignancy (GVM) effect, which eradicated metastatic melanoma in a minority of patients, but also involved an auto-GVHD reaction that resulted in widespread autoimmunity in the majority. Therefore, we argued for a profound theoretical point against the consensus of experts. The task is not to desperately put the genie back in the bottle by immune-suppressive treatments, but instead to harness the autoimmune forces. In this way, the same goal could be achieved by an antibody as by the adoptive transfer of alloreactive donor lymphocytes, but without severe GVHD. The proof-of-principle of a low-dose-combination immune checkpoint therapy, consisting only of approved drugs and treatments, was demonstrated in 111 stage IV cancer patients.
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http://dx.doi.org/10.1111/sji.12821DOI Listing
December 2019

The case for allele-specific recognition by the TCR.

Scand J Immunol 2019 Aug 3;90(2):e12790. Epub 2019 Jul 3.

Department of Oral Biology, Faculty of Dentistry, University of Oslo, Oslo, Norway.

There is a sharp difference in how one views TCR structure-function-behaviour dependent on whether its recognition of major histocompatibility complex-encoded restriction elements (R) is germline selected or somatically generated. The generally accepted or Standard model is built on the assumption that recognition of R is by the V regions of the αβ TCR, which is not driven by allele specificity, whereas the competing model posits that recognition of R is allele-specific. The establishing of allele-specific recognition of R by the TCR would rule out the Standard model and clear the road to a consideration of a competing construct, the Tritope model. Here, the case for allele-specific recognition (germline selected) is detailed making it obvious that the Standard model is untenable.
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http://dx.doi.org/10.1111/sji.12790DOI Listing
August 2019

Acute Maneb Exposure Significantly Alters Both Glycolysis and Mitochondrial Function in Neuroblastoma Cells.

Toxicol Sci 2018 09;165(1):61-73

Department of Pharmaceutical Sciences, Skaggs School of Pharmacy and Pharmaceutical Sciences, University of Colorado, Aurora, Colorado 80045.

The pesticides paraquat (PQ) and maneb (MB) have been described as environmental risk factors for Parkinson's disease (PD), with mechanisms associated with mitochondrial dysfunction and reactive oxygen species generation. A combined exposure of PQ and MB in murine models and neuroblastoma cells has been utilized to further advance understanding of the PD phenotype. MB acts as a redox modulator through alkylation of protein thiols and has been previously characterized to inhibit complex III of the electron transport chain and uncouple the mitochondrial proton gradient. The purpose of this study was to analyze ATP-linked respiration and glycolysis in human neuroblastoma cells utilizing the Seahorse extracellular flux platform. Employing an acute, subtoxic exposure of MB, this investigation revealed a MB-mediated decrease in mitochondrial oxygen consumption at baseline and maximal respiration, with inhibition of ATP synthesis and coupling efficiency. Additionally, MB-treated cells showed an increase in nonmitochondrial respiration and proton leak. Further investigation into mitochondrial fuel flex revealed an elimination of fuel flexibility across all 3 major substrates, with a decrease in pyruvate capacity as well as glutamine dependency. Analyses of glycolytic function showed a substantial decrease in glycolytic acidification caused by lactic acid export. This inhibition of glycolytic parameters was also observed after titrating the MB dose as low as 6 μM, and appears to be dependent on the dithiocarbamate functional group, with manganese possibly potentiating the effect. Further studies into cellular ATP and NAD levels revealed a drastic decrease in cells treated with MB. In summary, MB significantly impacted both aerobic and anaerobic energy production; therefore, further characterization of MB's effect on cellular energetics may provide insight into the specificity of PD to dopaminergic neurons.
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http://dx.doi.org/10.1093/toxsci/kfy116DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6135636PMC
September 2018

Stability of Chimerism in Non-Obese Diabetic Mice Achieved By Rapid T Cell Depletion Is Associated With High Levels of Donor Cells Very Early After Transplant.

Front Immunol 2018 24;9:837. Epub 2018 Apr 24.

Department of Surgery, University of Alberta, Edmonton, AB, Canada.

Stable mixed hematopoietic chimerism is a robust method for inducing donor-specific tolerance with the potential to prevent rejection of donor islets in recipients with autoimmune type-1 diabetes. However, with reduced intensity conditioning, fully allogeneic chimerism in a tolerance resistant autoimmune-prone non-obese diabetic (NOD) recipient has rarely been successful. In this setting, successful multilineage chimerism has required either partial major histocompatability complex matching, mega doses of bone marrow, or conditioning approaches that are not currently clinically feasible. Irradiation free protocols with moderate bone marrow doses have not generated full tolerance; donor skin grafts were rejected. We tested whether more efficient recipient T cell depletion would generate a more robust tolerance. We show that a combination of donor-specific transfusion-cyclophosphamide and multiple T cell depleting antibodies could induce stable high levels of fully allogeneic chimerism in NOD recipients. Less effective T cell depletion was associated with instability of chimerism. Stable chimeras appeared fully donor-specific tolerant, with clonal deletion of allospecific T cells and acceptance of donor skin grafts, while recovering substantial immunocompetence. The loss of chimerism months after transplant was significantly associated with a lower level of chimerism and donor T cells within the first 2 weeks after transplant. Thus, rapid and robust recipient T cell depletion allows for stable high levels of fully allogeneic chimerism and robust donor-specific tolerance in the stringent NOD model while using a clinically feasible protocol. In addition, these findings open the possibility of identifying recipients whose chimerism will later fail, stratifying patients for early intervention.
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http://dx.doi.org/10.3389/fimmu.2018.00837DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5928230PMC
June 2019

Prior to Peripheral Tolerance, Newly Generated CD4 T Cells Maintain Dangerous Autoimmune Potential: Fas- and Perforin-Independent Autoimmunity Controlled by Programmed Death-1.

Front Immunol 2018 24;9:12. Epub 2018 Jan 24.

Department of Medical Microbiology and Immunology, University of Alberta, Edmonton, AB, Canada.

Lymphopenia can result from various factors, including viral infections, clinical interventions, or as a normal property of the fetal/neonatal period. T cells in a lymphopenic environment undergo lymphopenia-induced proliferation (LIP) to fill the available "niche" as defined by peptide-MHC and homeostatic cytokine resources. We recently reported systemic autoimmunity following reconstitution of the lymphoid compartment of Rag1 mice with PD-1 hematopoietic stem cells or by transfer of thymocytes, but not splenocytes, suggesting that programmed death-1 (PD-1) plays a crucial role in controlling recent thymic emigrants (RTE) and preventing autoimmunity upon their LIP. However, it is unclear whether RTE residing within the periphery of a lymphoreplete host maintain enhanced autoimmune generating potential or if this property only manifests if RTE experience a lymphopenic periphery immediately after export from the thymus. Furthermore, it is unclear which of a variety of T cell effector mechanisms generate pathology when control of RTE by PD-1 is lacking. Herein, we determined that PD-1 is upregulated on CD4 T cells undergoing the natural LIP characteristic of the neonatal period. Newly generated T cells lacking PD-1 maintained an enhanced autoimmune potential even after residence in a lymphoreplete periphery, emphasizing the importance of PD-1 in the establishment of peripheral tolerance. Neither Fas nor perforin-dependent killing mechanisms were required for autoimmunity, while host MHC-II expression was critical, suggesting that LIP-driven autoimmunity in the absence of PD-1 may primarily result from a CD4 T cell-mediated systemic cytokinemia, a feature potentially shared by other autoimmune or inflammatory syndromes associated with immune reconstitution and LIP.
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http://dx.doi.org/10.3389/fimmu.2018.00012DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5787554PMC
February 2019

PD-1 Controls Tonic Signaling and Lymphopenia-Induced Proliferation of T Lymphocytes.

Front Immunol 2017 12;8:1289. Epub 2017 Oct 12.

Department of Medical Microbiology and Immunology, University of Alberta, Edmonton, AB, Canada.

Recovery of the T lymphocyte compartment within a lymphopenic host by lymphopenia-induced proliferation (LIP) is regulated by inter- and intraclonal competition for limited resources, including homeostatic cytokines and peptide:MHC (pMHC) complexes with which the TCR can interact at least weakly to yield a tonic signal. Importantly, the process of LIP can synergize with other factors that promote T cell activation to drive inflammatory disease. While reconstitution of the lymphoid compartment of immune deficient Rag mice by transfer of wild-type hematopoietic stem cells (HSC) does not generally result in an overt disease phenotype, transfer of HSC deficient in expression of the co-inhibitory molecule PD-1 results in severe systemic autoimmunity driven by newly generated T cells that emerge from the thymus into the periphery and undergo LIP. Importantly, autoimmunity does not appear to depend on a response to exogenous (i.e., gut flora-derived) antigens. PD-1 is well known to be upregulated during T cell activation in response to cognate antigens, but it is unclear whether PD-1 has a role in controlling LIP of T cells in the absence of cognate antigen, i.e., in response to tonic pMHC. We examined whether PD-1 controls LIP of newly generated T cells by controlling the response to tonic pMHC or the homeostatic cytokine IL-7. We found that PD-1-deficient T cells have a proliferative advantage over WT T cells during LIP and this effect is MHC-II dependent and independent of IL-7Rα signaling. Furthermore, our data suggest that signals through IL-7Rα can be dispensable for LIP and may instead be of increased importance for T cell survival in conditions of high competition for limited pMHC (e.g., post-LIP, in a lymphoreplete host). We hypothesize that autoimmunity post-PD-1 HSC transplant is the result of an overzealous T cell response to normally tonic self-pMHC precipitated by the synergy of LIP and PD-1 deficiency. Furthermore, potentiation of TCR signals in response to normally tonic self-pMHC may contribute to the success of PD-1 blockade in cancer immunotherapy.
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http://dx.doi.org/10.3389/fimmu.2017.01289DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5643416PMC
October 2017

Two Strikes and You're Out? The Pathogenic Interplay of Coinhibitor Deficiency and Lymphopenia-Induced Proliferation.

J Immunol 2017 04;198(7):2534-2541

Department of Medical Microbiology and Immunology, University of Alberta, Edmonton, Alberta T6G 2E1, Canada;

Lymphopenia-induced proliferation (LIP) occurs when resources for T cell survival in a host are in excess. LIP has been associated with the development of inflammatory disease in situations where an additional disease-predisposing cofactor is present during LIP. This has led to the view of LIP-driven autoimmunity as a two hit model; however, not all cofactors have equal ability to precipitate autoimmunity and we have recently shown that in some circumstances, such as the absence of the coinhibitory molecule PD-1, additional hits are required. Herein we review factors controlling LIP, including coinhibitory molecules and other attenuators of TCR signaling, with a focus on their contribution to LIP-driven autoimmunity. Rather than viewing LIP-associated autoimmunity as an -hit model, we suggest a more quantitative view of lymphopenia with respect to the factors that promote LIP as a tool to predict autoimmune potential and to inform tumor immunotherapy approaches.
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http://dx.doi.org/10.4049/jimmunol.1601884DOI Listing
April 2017

Morphologic and Histologic Comparison of Hypertrophic Scar in Nude Mice, T-Cell Receptor, and Recombination Activating Gene Knockout Mice.

Plast Reconstr Surg 2015 Dec;136(6):1192-1204

Ottawa and Hamilton, Ontario, and Edmonton, Alberta, Canada From the Division of Plastic and Reconstructive Surgery, University of Ottawa; Wound Healing Research Group and Alberta Diabetes Institute, Department of Surgery, and Divisions of Plastic and Reconstructive Surgery and Critical Care, University of Alberta; and the Division of Plastic and Reconstructive Surgery, McMaster University.

Background: Proliferative scars in nude mice have demonstrated morphologic and histologic similarities to human hypertrophic scar. Gene knockout technology provides the opportunity to study the effect of deleting immune cells in various disease processes. The authors' objective was to test whether grafting human skin onto T-cell receptor (TCR) αβ-/-γδ-/-, recombination activating gene (RAG)-1-/-, and RAG-2γ-/-c-/- mice results in proliferative scars consistent with human hypertrophic scar and to characterize the morphologic, histologic, and cellular changes that occur after removing immune cells.

Methods: Nude TCRαβ-/-γδ-/-, RAG-1-/-, and RAG-2-/-γc-/- mice (n = 20 per strain) were grafted with human skin and euthanized at 30, 60, 120, and 180 days. Controls (n = 5 per strain) were autografted with mouse skin. Scars and normal skin were harvested at each time point. Sections were stained with hematoxylin and eosin, Masson's trichrome, and immunohistochemistry for anti-human leukocyte antigen-ABC, α-smooth muscle actin, decorin, and biglycan.

Results: TCRαβ-/-γδ-/-, RAG-1-/-, and RAG-2-/-γc-/- mice grafted with human skin developed firm, elevated scars with histologic and immunohistochemical similarities to human hypertrophic scar. Autografted controls showed no evidence of pathologic scarring. Knockout animals demonstrated a capacity for scar remodeling not observed in nude mice where reductions in α-smooth muscle actin staining pattern and scar thickness occurred over time.

Conclusions: Human skin transplanted onto TCRαβ-/-γδ-/-, RAG-1-/-, and RAG-2-/-γc-/- mice results in proliferative scars with morphologic and histologic features of human hypertrophic scar. Remodeling of proliferative scars generated in knockout animals is analogous to changes in human hypertrophic scar. These animal models may better represent the natural history of human hypertrophic scar.
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http://dx.doi.org/10.1097/PRS.0000000000001782DOI Listing
December 2015

PD-1 is not required for natural or peripherally induced regulatory T cells: Severe autoimmunity despite normal production of regulatory T cells.

Eur J Immunol 2014 Dec 27;44(12):3560-72. Epub 2014 Oct 27.

Department of Medical Microbiology and Immunology, University of Alberta, Edmonton, AB, Canada; Alberta Diabetes and Transplant Institutes, University of Alberta, Edmonton, AB, Canada.

The expression of the coinhibitor PD-1 on T cells is important for the establishment of immune homeostasis. We previously found that PD-1 is particularly critical for the control of self-tolerance during lymphopenia-induced proliferation of recent thymic emigrants (RTEs). Previous studies suggested that PD-1 modulates the generation of Treg cells, particularly peripherally induced Treg (pTreg) cells, and controls Th17 cells. However, these conclusions were derived indirectly from studies on the ligand PD-L1, and not PD-1 itself. Herein we directly tested whether T-cell PD-1 expression was needed for Treg cell generation and examined if a paucity of Treg cells or enhanced Th17 cells could explain the severe lymphopenia-potentiated autoimmunity caused by PD-1 KO RTEs. Employing the murine FoxP3(EGFP) reporter system to simultaneously monitor conversion of WT and PD-1 KO T cells to pTreg cells in the same animal, we found that PD-1 deficiency did not inhibit pTreg cell generation or lead to Th17-cell-mediated autoimmunity. Surprisingly, pTreg cell numbers were increased in PD-1 KO versus WT cell populations. Furthermore, we noted an increased conversion to pTreg cells by RTEs. Our data suggest that the primary role for PD-1 is to restrain T-cell activation/proliferation to self-Ags rather than promote generation of Treg cells.
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http://dx.doi.org/10.1002/eji.201444688DOI Listing
December 2014

Application of central immunologic concepts to cancer: helping T cells and B cells become intolerant of tumors.

Authors:
Colin C Anderson

Eur J Immunol 2014 Jul;44(7):1921-4

Department of Surgery, University of Alberta, Edmonton, AB, Canada; Department of Medical Microbiology and Immunology, University of Alberta, Edmonton, AB, Canada; Alberta Diabetes and Transplant Institutes, University of Alberta, Edmonton, AB, Canada.

CD4-mediated T-cell help in the activation of CD8(+) T cells and B cells, through linked-recognition of antigenic determinants, is a long-standing concept foundational to our understanding of immunity (presence of help) versus tolerance (lack of help). Surprisingly, this function of CD4(+) T cells has not been extensively examined as a means to overcome immune tolerance of the self-antigens made by tumor cells. Hesitation to employ this powerful mechanism may be due to the potential to cause unwanted autoimmune pathology. In this issue of the European Journal of Immunology, Snook et al. [Eur. J. Immunol. 2014. 44: 1956-1966] identify a state of split tolerance, showing that CD4(+) T cells specific for a number of tumor-associated self-antigens are robustly tolerant, while their CD8(+) T-cell and B-cell counterparts are far less tolerant. Furthermore, the authors demonstrate that provision of linked foreign helper epitopes, such as influenza hemagglutinin, substantially enhances both CD8(+) T-cell and B-cell responses to tumor self-antigens without causing any overt autoimmune pathology. These findings provide a strong rationale to employ foreign helper epitopes in cancer vaccines and highlight the need to fully explore therapeutic strategies that are based on well-established immunologic concepts.
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http://dx.doi.org/10.1002/eji.201444826DOI Listing
July 2014

T cells generated in the absence of a thoracic thymus fail to establish homeostasis.

Eur J Immunol 2014 Aug 23;44(8):2263-73. Epub 2014 May 23.

Department of Medical Microbiology and Immunology, University of Alberta, Edmonton, AB, Canada.

Cervical thymus mimics the thoracic thymus in supporting T-cell development and exists in a subset of mice and humans. Importantly, it remains unknown whether the cervical thymus can generate T cells that are self-tolerant in the complete absence of signals from the thoracic thymus. Using a fetal liver reconstitution model in thoracic thymectomized RAG(-/-) mice, we found that T cells could be generated without contribution from the thoracic thymus. However, these mice had decreased T cells, increased proportions of effector memory T cells and Treg phenotype cells, increased serum IgG1/2b, and increased frequency of T cells expressing IFN-γ, IL-17 or IL-10. Half of the mice that received a thoracic thymectomy and fetal liver cells, unlike sham surgery controls, developed substantial morbidity with age. Disease was associated with lymphopenia-driven activation rather than inherent defects in the cervical thymus, as both thoracic and cervical thymocytes could generate disease in lymphopenic recipients. Administration of the homeostatic cytokine IL-7 caused a rapid, transient increase in T-cell numbers and reduced the time to disease onset. Together the data suggests that the cervical thymus can function in the complete absence of the thoracic thymus; however, the T cells generated do not establish homeostasis.
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http://dx.doi.org/10.1002/eji.201343846DOI Listing
August 2014

Control of in vivo collateral damage generated by T cell immunity.

J Immunol 2013 Aug 12;191(4):1686-91. Epub 2013 Jul 12.

Department of Surgery, University of Alberta, Edmonton, Alberta T6G 2E1, Canada.

An ongoing dilemma faced during an immune response is generating an effective, often proinflammatory response to eliminate pathogens and/or infected cells while also minimizing collateral damage to adjacent noninfected tissues. The factors limiting bystander cell injury during an Ag-specific immune response in vivo are largely unknown. In this study, using an in vivo model of islet transplants in TCR transgenic mice, we show that both CD4 and CD8 T cells do have the capacity to inflict adjacent tissue damage and that this injury is greatly enhanced in sensitized hosts. CD4 T cell-mediated killing of specific and bystander cells occurred via different mechanisms. Unlike specific target cell killing, CD4-mediated bystander injury required tissue Fas expression and was inhibited with anti-IFN-γ Ab treatment in vivo. Moreover, bystander cell injury was not entirely nonspecific but rather required, in naive recipients, that the MHC allele expressed by the bystanders was self. Importantly, the coinhibitor programmed death-1 plays an important role in restraining bystander cell injury mediated either by defined TCR transgenic T cells or by polyclonal T cell populations. Thus, the differential requirements for specific versus bystander cell injury suggest that there are opportunities for inhibiting immune pathology without compromising Ag-specific immunity in vivo.
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http://dx.doi.org/10.4049/jimmunol.1203240DOI Listing
August 2013

A discussion of immune tolerance and the layered immune system hypothesis.

Chimerism 2013 Jul-Sep;4(3):62-70. Epub 2013 May 3.

Department of Cell and Molecular Biology; Karolinska Institutet; Stockholm, Sweden.

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http://dx.doi.org/10.4161/chim.24914DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3782546PMC
April 2014

Toward minimal conditioning protocols for allogeneic chimerism in tolerance resistant recipients.

Chimerism 2013 Jan-Mar;4(1):23-5. Epub 2013 Jan 1.

Department of Surgery, Alberta Diabetes Institute, University of Alberta, Edmonton, AB Canada.

Mixed chimerism is a promising approach toward generating donor-specific immunological tolerance. However, chimerism induction can be toxic; therefore, there is an effort to develop non-myeloablative, minimal intensity protocols that can generate chimerism without the toxic side effects. Recently, with the goal of creating a minimalistic chimerism induction protocol in the tolerance resistant non-obese diabetic (NOD) mouse model, we identified pre-existing T cells as cells that resist fully allogeneic chimerism. With monoclonals targeting NOD T cells, we showed that long-term chimerism and tolerance toward donor islets could be established. However, this promising new protocol relied on the administration of a single dose of anti-CD40 ligand, which is not clinically applicable. In refining protocols to move even closer to clinical utility, we report here initial success at generating fully allogeneic mixed chimerism in NOD mice by adding cyclophosphamide to the conditioning regimen in place of anti-CD40 ligand antibodies.
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http://dx.doi.org/10.4161/chim.23350DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3654734PMC
December 2013
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