scholarly journals The M2 Gene Is a Determinant of Reovirus-Induced Myocarditis

2021 ◽  
Author(s):  
Marcelle Dina Zita ◽  
Matthew B. Phillips ◽  
Johnasha D. Stuart ◽  
Asangi R. Kumarapeli ◽  
Anthony J. Snyder ◽  
...  
Keyword(s):  
Genetic Background ◽  
Caspase 3 ◽  
Viral Myocarditis ◽  
Small Subset ◽  
Inflammatory Infiltration ◽  
Lethal Infection ◽  
Strain Type ◽  
Type 3

Although a broad range of viruses cause myocarditis, the mechanisms that underlie viral myocarditis are poorly understood. Here, we report that the M2 gene is a determinant of reovirus myocarditis. The M2 gene encodes outer capsid protein μ1, which mediates host membrane penetration during reovirus entry. We infected newborn C57BL/6 mice with reovirus strain type 1 Lang (T1L) or a reassortant reovirus in which the M2 gene from strain type 3 Dearing (T3D) was substituted into the T1L genetic background (T1L/T3DM2). T1L was non-lethal in wild-type mice, whereas greater than 90% of mice succumbed to T1L/T3DM2 infection. T1L/T3DM2 produced higher viral loads than T1L at the site of inoculation. In secondary organs, T1L/T3DM2 was detected with more rapid kinetics and reached higher peak titers than T1L. We found that hearts from T1L/T3DM2-infected mice were grossly abnormal, with large lesions indicative of substantial inflammatory infiltrate. Lesions in T1L/T3DM2-infected mice contained necrotic cardiomyocytes with pyknotic debris, and extensive lymphocyte and histiocyte infiltration. In contrast, T1L induced the formation of small purulent lesions in a small subset of animals, consistent with T1L being mildly myocarditic. Finally, more activated caspase-3-positive cells were observed in hearts from animals infected with T1L/T3DM2 compared to T1L. Together, our findings indicate that substitution of the T3D M2 allele into an otherwise T1L genetic background is sufficient to change a non-lethal infection into a lethal infection. Our results further indicate that T3D M2 enhances T1L replication and dissemination in vivo , which potentiates the capacity of reovirus to cause myocarditis. IMPORTANCE Reovirus is a non-enveloped virus with a segmented double-stranded RNA genome that serves as a model for studying viral myocarditis. The mechanisms by which reovirus drives myocarditis development are not fully elucidated. We found that substituting the M2 gene from strain type 3 Dearing (T3D) into an otherwise type 1 Lang (T1L) genetic background (T1L/T3DM2) was sufficient to convert the non-lethal T1L strain into a lethal infection in neonatal C57BL/6 mice. T1L/T3DM2 disseminated more efficiently and reached higher maximum titers than T1L in all organs tested, including the heart. T1L is mildly myocarditic and induced small areas of cardiac inflammation in a subset of mice. In contrast, hearts from mice infected with T1L/T3DM2 contained extensive cardiac inflammatory infiltration and more activated caspase-3-positive cells, which is indicative of apoptosis. Together, our findings identify the reovirus M2 gene as a new determinant of reovirus-induced myocarditis.

scholarly journals The M2 Gene Is a Determinant of Reovirus-Induced Myocarditis

2021 ◽  
Author(s):  
Marcelle Dina Zita ◽  
Matthew B Phillips ◽  
Johnasha D. Stuart ◽  
Asangi R Kumarapeli ◽  
Vijayalakshmi Sridharan ◽  
...  
Keyword(s):  
Cardiac Injury ◽  
Viral Myocarditis ◽  
Newborn Mice ◽  
Viral Loads ◽  
Lethal Infection ◽  
Strain Type ◽  
Rapid Kinetics ◽  
Inflammatory Infiltrates ◽  
Type 3

Although a broad range of viruses cause myocarditis, the mechanisms that underlie viral myocarditis are poorly understood. Here, we report that the M2 gene is a determinant of reovirus myocarditis. The reovirus M2 gene encodes outer capsid protein µ1, which influences both cell entry and cell death. We infected newborn mice with reovirus strain type 1 Lang (T1L) or a reassortant reovirus in which the M2 gene from strain type 3 Dearing (T3D) was substituted into the T1L background (T1L/T3DM2). T1L was non-lethal in wild-type mice, whereas ~ 90% of mice succumbed to T1L/T3DM2. T1L/T3DM2 produced higher viral loads than T1L at the site of inoculation. In secondary organs, T1L/T3DM2 was detected with more rapid kinetics and reached higher peak titers than T1L. We found that hearts from T1L/T3DM2-infected mice were grossly abnormal, with large lesions corresponding to substantial cardiac injury with inflammatory infiltrates. Lesions in T1L/T3DM2-infected mice contained aggregates of necrotic cardiomyocytes with pyknotic debris, and prominent lymphocyte and histiocyte infiltration. In contrast, T1L induced the formation of smaller lesions in a subset of animals, consistent with T1L being mildly myocarditic. Finally, more activated caspase-3-positive cells were observed in hearts from animals infected with T1L/T3DM2 compared to T1L. Together, our findings indicate that substitution of the T3D M2 allele into an otherwise T1L genetic background is sufficient to change a non-lethal infection into a lethal infection. Our results further indicate that T3D M2 enhances T1L replication and dissemination in vivo, which potentiates the capacity of reovirus to cause myocarditis.

scholarly journals Modeling Type 1 Diabetes Using Pluripotent Stem Cell Technology

2021 ◽  
Vol 12 ◽  
Author(s):  
Kriti Joshi ◽  
Fergus Cameron ◽  
Swasti Tiwari ◽  
Stuart I. Mannering ◽  
Andrew G. Elefanty ◽  
...  
Keyword(s):  
Type 1 Diabetes ◽  
Stem Cell ◽  
Genetic Variants ◽  
Genetic Background ◽  
Pluripotent Stem Cell ◽  
Cell Types ◽  
Polygenic Inheritance

Induced pluripotent stem cell (iPSC) technology is increasingly being used to create in vitro models of monogenic human disorders. This is possible because, by and large, the phenotypic consequences of such genetic variants are often confined to a specific and known cell type, and the genetic variants themselves can be clearly identified and controlled for using a standardized genetic background. In contrast, complex conditions such as autoimmune Type 1 diabetes (T1D) have a polygenic inheritance and are subject to diverse environmental influences. Moreover, the potential cell types thought to contribute to disease progression are many and varied. Furthermore, as HLA matching is critical for cell-cell interactions in disease pathogenesis, any model that seeks to test the involvement of particular cell types must take this restriction into account. As such, creation of an in vitro model of T1D will require a system that is cognizant of genetic background and enables the interaction of cells representing multiple lineages to be examined in the context of the relevant environmental disease triggers. In addition, as many of the lineages critical to the development of T1D cannot be easily generated from iPSCs, such models will likely require combinations of cell types derived from in vitro and in vivo sources. In this review we imagine what an ideal in vitro model of T1D might look like and discuss how the required elements could be feasibly assembled using existing technologies. We also examine recent advances towards this goal and discuss potential uses of this technology in contributing to our understanding of the mechanisms underlying this autoimmune condition.

scholarly journals Genetic and Biochemical Studies of Polioviruscis-Acting Replication Element cre in Relation to VPg Uridylylation

2000 ◽  
Vol 74 (22) ◽  
pp. 10371-10380 ◽  
Author(s):  
Elizabeth Rieder ◽  
Aniko V. Paul ◽  
Dong Wook Kim ◽  
Jacques H. van Boom ◽  
Eckard Wimmer
Keyword(s):  
Genome Replication ◽  
Coding Region ◽  
Stem Loop ◽  
Genetic Changes ◽  
Poliovirus Type ◽  
Type 3 ◽  
Type Sequence

ABSTRACT In addition to highly conserved stem-loop structures located in the 5′- and 3′-nontranslated regions, genome replication of picornaviruses requires cis-acting RNA elements located in the coding region (termed cre) (K. L. McKnight and S. M. Lemon, J. Virol. 70:1941–1952, 1996; P. E. Lobert, N. Escriou, J. Ruelle, and T. Michiels, Proc. Natl. Acad. Sci. USA 96:11560–11565, 1999; I. Goodfellow, Y. Chaudhry, A. Richardson, J. Meredith, J. W. Almond, W. Barclay, and D. J. Evans, J. Virol. 74:4590–4600, 2000). cre elements appear to be essential for minus-strand RNA synthesis by an as-yet-unknown mechanism. We have discovered that the cre element of poliovirus (mapping to the 2C coding region of poliovirus type 1; nucleotides 4444 to 4505 in 2C), which is homologous to thecre element of poliovirus type 3, is preferentially used as a template for the in vitro uridylylation of VPg catalyzed by 3Dpol in a reaction that is greatly stimulated by 3CDpro (A. V. Paul, E. Rieder, D. W. Kim, J. H. van Boom, and E. Wimmer, J. Virol. 74:10359–10370, 2000). Here we report a direct correlation between mutations that eliminate, or severely reduce, the in vitro VPg-uridylylation reaction and produce replication phenotypes in vivo. None of the genetic changes significantly influenced translation or polyprotein processing. A substitution mapping to the first A (A4472C) of a conservedAAACA sequence in the loop of PV-cre(2C) eliminated the ability of the cre RNA to serve as template for VPg uridylylation and abolished RNA infectivity. Mutagenesis of the second A (A4473C; AAACA) severely reduced the yield of VPgpUpU and RNA infectivity was restored only after reversion to the wild-type sequence. The effect of substitution of the third A (A4474G; AAACA) was less severe but reduced both VPg uridylylation and virus yield. Disruption of base pairing within the upper stem region of PV-cre(2C) also affected uridylylation of VPg. Virus derived from transcripts containing mutations in the stem was either viable or quasi-infectious.

New Fine Structure within the Adult Hematopoietic Stem Cell Compartment Revealed by Longterm Analysis of Mice Repopulated with Single Cells or Their In Vitro Generated Clonal Progeny.

Blood ◽  
2005 ◽  
Vol 106 (11) ◽  
pp. 1720-1720
Author(s):  
Brad Dykstra ◽  
David Kent ◽  
Lindsay McCaffrey ◽  
Kristin Lyons ◽  
Merete Kristiansen ◽  
...  
Keyword(s):  
Stem Cell ◽  
Hematopoietic Stem Cell ◽  
Single Cells ◽  
Myeloid Cells ◽  
Hematopoietic Stem ◽  
Type 3

Abstract Assessments of hematopoietic stem cell (HSC) repopulating activity in vivo have historically relied on calculated average longterm (12–16 wk) progeny outputs using non-purified transplants, thereby precluding definitive clonal assignments of donor-derived cells. Viral marking circumvents this problem, but has not been used for large scale surveys. Heterogeneity observed in the repopulation patterns has generally been inferred to reflect stochastic processes. We now report the in vivo repopulation kinetics of 89 individual longterm repopulating cells (LTRCs) before (n=49) and after (n=40) 4 days of clonal growth in vitro. LTRCs were defined here as cells whose WBC progeny could be detected at levels of ≥1% for at least 16 wk in sublethally irradiated Ly5-congenic W41/W41 hosts. Recipients were transplanted with either freshly isolated, single lin−Rho−SP LTRCs or 4-day clones generated from similar cells in serum-free cultures (+ 300 ng/ml SF, 20 ng/ml IL-11 & 1ng/ml Flt3-L). 4, 8, 12, 16, and 24 wk post-transplant, blood samples were stained for donor-derived B, T, and myeloid cells using a procedure that identifies donor/recipient doublets and Ly6g/Mac1low cells (which have features of lymphoid rather than myeloid WBCs) to exclude false-positive myeloid events. Four distinct patterns of repopulation were revealed. Type 1 showed a delayed production of predominantly myeloid WBCs (low or undetectable before 12 wk) that increased progressively (reaching 0.4–15% of all WBCs by 16 wk). Type 2 showed a robust multilineage repopulation that remained stable or increased over time (6–84% of all WBCs at 16 wk). Type 3 also showed an initially robust pattern of multilineage repopulation (peak numbers of WBCs at 8–12 wk and 1–51% at 16 wk), but the contribution of donor-derived myeloid cells was transient (<0.5% by 16 wk). Type 4 showed a lymphoid-restricted pattern (myeloid contribution <0.5% at all time points), with repopulation levels peaking at 8 wk and decreasing thereafter (1–22% at 16 wk). Persisting granulopoiesis, indicated by a high proportion of donor-derived cells in the Ly6g/Mac1+SSChi population at 16–24 wk, clearly distinguished the type 1 and 2 patterns from types 3 and 4 which showed near or complete cessation of donor-derived granulopoiesis beyond 12 wk. Preliminary secondary transplant experiments show that donor-derived LTRCs (with and without longterm granulopoietic activity) were exclusively generated in primary recipients with type 1 and 2 repopulation patterns. Amongst the freshly isolated LTRCs, 18% (9/49) were type 1, 41% (20/49) were type 2, 22% (11/49) were type 3, and 18% (9/49) were type 4. In contrast, 4-day clones derived from cells of the same phenotype and containing LTRC activity showed a marked decrease in type 1 and type 2 activity with a corresponding increase in type 3 and type 4 activity: type 1 = 5% (2/41), type 2 = 18% (7/40), type 3 = 28% (11/40) and type 4 = 50% (20/40). Collectively, these data identify a new hierarchy of four biologically discrete states within the compartment of cells currently defined as LTRCs. Proliferation of LTRCs either in vitro or in vivo appears to induce an irreversible transition from one state to another (from Type 1 to 2 to 3 to 4), suggesting the existence of intrinsic molecular correlates for each of these states and specific mechanisms that underlie their sequential appearance.

Daratumumab, a Novel Therapeutic Human CD38 Monoclonal Antibody, Induces Killing of Refractory Patient-Derived Multiple Myeloma Cells, Growing in a Novel Humanized Mouse MM Model

Blood ◽  
2012 ◽  
Vol 120 (21) ◽  
pp. 940-940
Author(s):  
Willy A Noort ◽  
Richard W.J. Groen ◽  
Reinier Raymakers ◽  
Linda Aalders ◽  
Frans M Hofhuis ◽  
...  
Keyword(s):  
Multiple Myeloma ◽  
Tumor Cells ◽  
Research Funding ◽  
Humanized Mouse ◽  
Myeloma Cells ◽  
Tumor Load ◽  
Type 3

Abstract Abstract 940 The evolution of multiple myeloma (MM) is a multi-step process during which mature B cells acquire genetic mutations in multiple genes, which typically takes place in the bone marrow (BM) microenvironment. This, together with the difficulty to culture MM in vitro or to grow MM in vivo in animal models has been the main reason during past decades for poor progress in preclinical research with patient-derived myeloma (pMM) cells. Recently, we developed a unique human-mouse hybrid model that allows engraftment and outgrowth of pMM cells by implementing a technology that is based on first generating a human bone environment in immune deficient mice (Groen et al. 2012) and that is subsequently capable of supporting growth of injected pMM cells. The model offers the opportunity (1) to study the pathobiology of myeloma, and (2) to evaluate, preclinically, new therapeutics for MM treatment, including antibody testing against pMM cells, obtained from patients who acquired resistance to conventional and novel drugs. Daratumumab (DARA) is a human CD38 antibody with broad-spectrum killing activity. Daratumumab induces effective killing of MM tumor cells via complement dependent cytolysis (CDC), ADCC (antibody dependent cellular cytolysis) and ADCP (antibody-dependent phagocytosis). DARA represents a novel promising treatment for MM and other hematological malignancies and is currently tested in Phase I/II clinical trials. In these clinical studies the adverse events have been manageable and marked reductions in paraprotein and bone marrow plasma cells have been observed. In the current study, we asked whether DARA was able to inhibit growth of refractory tumor cells in our human-mouse hybrid model. To this end, immune-deficient RAG2−/−gc−/−-mice were implanted subcutaneously with biphasic calcium phosphate (BCP) particles (2–3 mm) loaded with culture expanded human mesenchymal stromal cells (MSCs). Eight weeks later, the humanized scaffolds in mice (n=45) were injected with 0.5–5×106 pMM cells obtained from different refractory, MM patients. The pMM cells were gene-marked with a GFP-luciferase lentiviral construct for imaging of viable tumor cells. Bioluminescent imaging (BLI) was used to follow myeloma outgrowth in time and to visualize the effect of treatment. The pMM cells were obtained from patients at diagnosis (type 1); at end stage disease, after a history of MPT (melphalan, prednisone, thalidomide, type 2); or from a patient refractory to chemotherapy with bortezomib (BORT), adriamycine and dexamethasone (DEX) (type 3). Mice carrying the pMM cells received similar treatment as the patients or were treated with DARA in a dose range of 1x 50 μg (low dose (LD)) or 2 to 3x 200 μg/mouse (high dose (HD)). BLI showed that the type 1 pMM-bearing mice responded well to all treatments, including DARA; type 2-bearing pMM mice showed no reduction in tumor growth after chemotherapy, but DARA treatment (LD) resulted in an almost complete elimination of circulating MM cells, as assessed with a CD138 antibody, in blood and BM. In a second experiment, type 2-pMM bearing mice were treated with a high DARA dose early (day 34, 50 and 72, 3 times HD, tumor size/BLI signal <200 cmp/cm2) or late (day 50 and 72, 2 times HD, tumor size/BLI signal >8000 cpm/cm2). A significant reduction of overall tumor load, as measured with BLI was observed, which interestingly did not differ between the high and low tumor load group. A reduction of circulating tumor cells (CD138+) was observed for both conditions, which was most obvious in the early treated mice and in agreement with the observations in the first experiment. Type 3 (resistant) pMM-bearing mice showed only a minor response to DEX and BORT, but were highly sensitive to melphalan. When DEX- and BORT-treated mice were treated with a single injection of DARA, this resulted in a complete remission in 3 out of 4 mice and a reduction of the tumor load by 50% in the fourth BORT-treated mouse. In conclusion, our results demonstrate that DARA is effective against multiple myeloma cells derived from therapy- naïve or -refractory patients grafted in a humanized mouse model. In addition, this humanized MM model can be used to study the potential and mechanism of action of DARA in vivo. This novel MM model might be used to predict responsiveness of myeloma patients to particular treatments. Disclosures: Groen: Genmab BV: Research Funding. Raymakers:Novartis: Consultancy. Lammerts van Bueren:Genmab BV: Employment. Parren:genmab: Employment. Mutis:genmab: Research Funding. Martens:Genmab BV: Research Funding.

scholarly journals Caspase Inhibition Protects against Reovirus-Induced Myocardial Injury In Vitro and In Vivo

2004 ◽  
Vol 78 (20) ◽  
pp. 11040-11050 ◽  
Author(s):  
Roberta L. DeBiasi ◽  
Bridget A. Robinson ◽  
Barbara Sherry ◽  
Ron Bouchard ◽  
R. Dale Brown ◽  
...  
Keyword(s):  
Viral Infection ◽  
Myocardial Injury ◽  
Caspase 3 ◽  
Viral Myocarditis ◽  
High Morbidity ◽  
Caspase Activity ◽  
Caspase Inhibition ◽  
Pharmacologic Agents

ABSTRACT Viral myocarditis is a disease with a high morbidity and mortality. The pathogenesis of this disease remains poorly characterized, with components of both direct virus-mediated and secondary inflammatory and immune responses contributing to disease. Apoptosis has increasingly been viewed as an important mechanism of myocardial injury in noninfectious models of cardiac disease, including ischemia and failure. Using a reovirus murine model of viral myocarditis, we characterized and targeted apoptosis as a key mechanism of virus-associated myocardial injury in vitro and in vivo. We demonstrated caspase-3 activation, in conjunction with terminal deoxynucleotidyltransferase-mediated dUTP-biotin nick end labeling and annexin binding, in cardiac myocytes after myocarditic viral infection in vitro. We also demonstrated a tight temporal and geographical correlation between caspase-3 activation, histologic injury, and viral load in cardiac tissue after myocarditic viral infection in vivo. Two pharmacologic agents that broadly inhibit caspase activity, Q-VD-OPH and Z-VAD(OMe)-FMK, effectively inhibited virus-induced cellular death in vitro. The inhibition of caspase activity in vivo by the use of pharmacologic agents as well as genetic manipulation reduced virus-induced myocardial injury by 40 to 60% and dramatically improved survival in infected caspase-3-deficient animals. This study indicates that apoptosis plays a critical role in mediating cardiac injury in the setting of viral myocarditis and is the first demonstration that caspase inhibition may serve as a novel therapeutic strategy for this devastating disease.

Application of in-body tissue architecture–induced Biotube vascular grafts for vascular access: Proof of concept in a beagle dog model

2019 ◽  
Vol 21 (3) ◽  
pp. 314-321 ◽  
Author(s):  
Maya Furukoshi ◽  
Eisuke Tatsumi ◽  
Yasuhide Nakayama
Keyword(s):  
Vascular Access ◽  
Body Tissue ◽  
Internal Diameter ◽  
Proof Of Concept ◽  
Beagle Dogs ◽  
Tissue Architecture ◽  
First Choice ◽  
Type 3

Introduction: The first choice of vascular access for hemodialysis is an autogenous arteriovenous fistula, because prosthetic arteriovenous grafts have a high probability of failure. In this study, Biotubes, in-body tissue architecture–induced autologous collagenous tubes, were evaluated for their potential use as vascular access grafts. Three animal implantation models were developed using beagle dogs, and the in vivo performance of Biotubes was observed after implantation in the acute phase as a pilot study. Methods: Biotubes (internal diameter ca. 4.0 mm, length ca. 5.0 cm, and wall thickness ca. 0.7 mm) were prepared through subcutaneous embedding of specially designed molds in beagle dogs for 8 weeks. The Biotubes were then implanted between the common carotid artery and the jugular vein of beagles via three methods, including side-to-side (in) -end-to-end (out) as type 1 (n = 4), side-to-side (both) as type 2 (n = 4), and side-to-end (in) -end-to-side (out) as type 3 (n = 1 using a composite Biotube). Results: Although two cases in type 1 and 2 resulted in Biotube deformation, all cases were patent for 4 weeks and maintained a continuous turbulent flow. At 4 weeks after implantation, percutaneous puncture could be performed repeatedly without aneurysm formation or hemorrhage. Conclusion: Within a short implantation period, with limited animal numbers, this proof-of-concept study showed that Biotubes may have a high potential for use in vascular access.

scholarly journals DIAGNOSIS OF ENDOCRINE DISEASE: 18-Oxocortisol and 18-hydroxycortisol: is there clinical utility of these steroids?

2018 ◽  
Vol 178 (1) ◽  
pp. R1-R9 ◽  
Author(s):  
Jacques W M Lenders ◽  
Tracy Ann Williams ◽  
Martin Reincke ◽  
Celso E Gomez-Sanchez
Keyword(s):  
Primary Aldosteronism ◽  
Zona Glomerulosa ◽  
Zona Fasciculata ◽  
Endocrine Disease ◽  
Familial Hyperaldosteronism ◽  
High Concentrations ◽  
And Function ◽  
Type 3

Since the early 1980s 18-hydroxycortisol and 18-oxocortisol have attracted attention when it was shown that the urinary excretion of these hybrid steroids was increased in primary aldosteronism. The development and more widespread use of specific assays has improved the understanding of their role in the (patho)physiology of adrenal disorders. The adrenal site of synthesis is not fully understood although it is clear that for the synthesis of 18-hydroxycortisol and 18-oxocortisol the action of both aldosterone synthase (zona glomerulosa) and 17α-hydroxylase (zona fasciculata) is required with cortisol as main substrate. The major physiological regulator is ACTH and the biological activity of both steroids is very low and therefore only very high concentrations might be effectivein vivo. In healthy subjects, the secretion of both steroids is low with 18-hydroxycortisol being substantially higher than that of 18-oxocortisol. The highest secretion of both steroids has been found in familial hyperaldosteronism type 1 (glucocorticoid-remediable aldosteronism) and in familial hyperaldosteronism type 3. Lower but yet substantially increased secretion is found in patients with aldosterone-producing adenomas in contrast to bilateral hyperplasia in whom the levels are similar to patients with hypertension. Several studies have attempted to show that these steroids, in particular, peripheral venous plasma 18-oxocortisol, might be a useful discriminatory biomarker for subtyping PA patients. The current available limited evidence precludes the use of these steroids for subtyping. We review the biosynthesis, regulation and function of 18-hydroxycortisol and 18-oxocortisol and their potential utility for the diagnosis and differential diagnosis of patients with primary aldosteronism.

scholarly journals Noncanonical Cell Death Induction by Reassortant Reovirus

2020 ◽  
Vol 94 (22) ◽  
Author(s):  
Roxana M. Rodríguez Stewart ◽  
Vishnu Raghuram ◽  
Jameson T. L. Berry ◽  
Gaurav N. Joshi ◽  
Bernardo A. Mainou
Keyword(s):  
Breast Cancer ◽  
Cell Death ◽  
Host Cell ◽  
Caspase 3 ◽  
Gene Segment ◽  
Oncolytic Viruses ◽  
Viral Gene ◽  
Genetic Composition ◽  
Type 3

ABSTRACT Triple-negative breast cancer (TNBC) constitutes 10 to 15% of all breast cancer and is associated with worse prognosis than other subtypes of breast cancer. Current therapies are limited to cytotoxic chemotherapy, radiation, and surgery, leaving a need for targeted therapeutics to improve outcomes for TNBC patients. Mammalian orthoreovirus (reovirus) is a nonenveloped, segmented, double-stranded RNA virus in the Reoviridae family. Reovirus preferentially kills transformed cells and is in clinical trials to assess its efficacy against several types of cancer. We previously engineered a reassortant reovirus, r2Reovirus, that infects TNBC cells more efficiently and induces cell death with faster kinetics than parental reoviruses. In this study, we sought to understand the mechanisms by which r2Reovirus induces cell death in TNBC cells. We show that r2Reovirus infection of TNBC cells of a mesenchymal stem-like (MSL) lineage downregulates the mitogen-activated protein kinase/extracellular signal-related kinase pathway and induces nonconventional cell death that is caspase-dependent but caspase 3-independent. Infection of different MSL lineage TNBC cells with r2Reovirus results in caspase 3-dependent cell death. We map the enhanced oncolytic properties of r2Reovirus in TNBC to epistatic interactions between the type 3 Dearing M2 gene segment and type 1 Lang genes. These findings suggest that the genetic composition of the host cell impacts the mechanism of reovirus-induced cell death in TNBC. Together, our data show that understanding host and virus determinants of cell death can identify novel properties and interactions between host and viral gene products that can be exploited for the development of improved viral oncolytics. IMPORTANCE TNBC is unresponsive to hormone therapies, leaving patients afflicted with this disease with limited treatment options. We previously engineered an oncolytic reovirus (r2Reovirus) with enhanced infective and cytotoxic properties in TNBC cells. However, how r2Reovirus promotes TNBC cell death is not known. In this study, we show that reassortant r2Reovirus can promote nonconventional caspase-dependent but caspase 3-independent cell death and that the mechanism of cell death depends on the genetic composition of the host cell. We also map the enhanced oncolytic properties of r2Reovirus in TNBC to interactions between a type 3 M2 gene segment and type 1 genes. Our data show that understanding the interplay between the host cell environment and the genetic composition of oncolytic viruses is crucial for the development of efficacious viral oncolytics.

scholarly journals A mathematical model of rat ascending Henle limb. III. Tubular function

2010 ◽  
Vol 298 (3) ◽  
pp. F543-F556 ◽  
Author(s):  
Alan M. Weinstein
Keyword(s):  
Mathematical Model ◽  
Tubular Function ◽  
Proton Secretion ◽  
Luminal Membrane ◽  
Catalytic Role ◽  
Type 3

K+ plays a catalytic role in AHL Na+ reabsorption via Na+-K+-2Cl− cotransporter (NKCC2), recycling across luminal K+ channels, so that luminal K+ is not depleted. Based on models of the ascending Henle limb (AHL) epithelium, it has been hypothesized that NH4+ may also catalyze luminal Na+ uptake. This hypothesis requires that luminal NH4+ not be depleted, implying replenishment via either direct secretion of NH4+, or NH3 in parallel with a proton. In the present work, epithelial models of rat medullary and cortical AHL (Weinstein AM, Krahn TA. Am J Physiol Renal Physiol 298: F000–F000, 2009) are configured as tubules and examined in simulations of function in vitro and in vivo to assess the feasibility of a catalytic role for NH4+ in Na+ reabsorption. Modulation of Na+ transport is also examined by peritubular K+ concentration and by Bartter-type transport defects in NKCC2 (type 1), in luminal membrane K+ channels (type 2), and in peritubular Cl− channels (type 3). It is found that a catalytic role for NH4+, which is significant in magnitude (relative to K+), is quantitatively realistic, in terms of uptake via NKCC2, and in terms of luminal membrane ammonia backflux. Simulation of a 90% NKCC2 defect is predicted to double distal Na+ delivery; it is also predicted to increase distal acid delivery (principally as NH4+). With doubling of medullary K+, the model predicts a 30% increase in distal Na+ delivery, but in this case there is a decrease in AHL acidification. This effect of peritubular K+ on proton secretion appears to be akin to type 3 Bartter's pathophysiology, in which there is decreased peritubular HCO3− exit, cytosolic alkalinization, and a consequent decrease in luminal proton secretion by NHE3. One consequence of overlapping and redundant roles for K+ and NH4+, is a blunted impact of luminal membrane K+ permeability on overall Na+ reabsorption, so that type 2 Bartter pathophysiology is not well captured by the model.

Sign in / Sign up

Export Citation Format

Share Document