89 research outputs found
Human enterovirus group B viruses rely on vimentin dynamics for efficient processing of viral non-structural proteins
We report that several viruses from the human enterovirus group B cause massive vimentin rearrangements during lytic infection. Comprehensive studies suggested that viral protein synthesis was triggering the vimentin rearrangements. Blocking the host cell vimentin dynamics with IDPN did not significantly affect the production of progeny viruses and only moderately lowered the synthesis of structural proteins such as VP1. In contrast, the synthesis of the non-structural proteins 2A, 3C, and 3D was drastically lowered. This led to attenuation of the cleavage of the host cell substrates PABP and G3BP1 and reduced caspase activation, thus leading to prolonged cell survival. Furthermore, the localization of the proteins differed in the infected cells. Capsid protein VP1 was found diffusely around the cytoplasm, whereas 2A and 3D followed vimentin distribution. Based on protein blotting, lower amounts of non-structural proteins did not result from proteasomal degradation, but from lower synthesis without intact vimentin cage structure. In contrast, inhibition of Hsp90 chaperone activity, which regulates P1 maturation, lowered the amount of VP1, but had less effect on 2A. The results suggest that, the vimentin dynamics regulate viral non-structural protein synthesis while having no effect on structural protein synthesis or overall infection efficiency. The results presented here shed new light on differential fate of structural and non-structural proteins of enteroviruses, having consequences on host cell survival.
Importance A virus needs the host cell in order to replicate and produce new progeny viruses. For this, the virus takes over the host cell and modifies it to become a factory for viral proteins. Irrespective of the specific virus family, these proteins can be divided into structural and non-structural proteins. Structural proteins are the building blocks for the new progeny virions, whereas the non-structural proteins orchestrate the take-over of the host cell and its functions. Here we have shown a mechanism that viruses exploit in order to regulate the host cell. We show that viral protein synthesis induces vimentin cages, which promote production of specific viral proteins that eventually control apoptosis and the host cell death. This study specifies vimentin as the key regulator of these events and indicates that viral proteins have different fates in the cells depending on their association with vimentin cages.peerReviewe
Melanoma differentiation-associated protein-5 (MDA-5) limits early viral replication but is not essential for the induction of type 1 interferons after Coxsackievirus infection
AbstractCoxsackievirus infections are associated with severe diseases such as myocarditis, meningitis and pancreatitis. To study the contribution of the intracellular viral sensor melanoma differentiation-associated protein-5 (MDA-5) in the host immune response to Coxsackievirus B3 (CVB3) we infected C57BL/6 and 129/SvJ mice lacking mda-5. Mice deficient in MDA-5 showed a dramatically increased susceptibility to CVB3 infection. The loss of MDA-5 allowed the virus to replicate faster, resulting in increased liver and pancreas damage and heightened mortality. MDA-5 was not absolutely required for the induction of type 1 interferons (IFNs), but essential for the production of maximal levels of systemic IFN-α early after infection. Taken together, our findings indicate that MDA-5 plays an important role in the host immune response to CVB3 by preventing early virus replication and limiting tissue pathology
Clinical impact of vitamin D treatment in cystic fibrosis: a pilot randomized, controlled trial
BACKGROUND/OBJECTIVES: Vitamin D insufficiency in cystic fibrosis is common. Vitamin D3 is currently preferred over D2. We aimed to study the efficacy of vitamin D2 and D3 at increasing serum 25-hydroxyvitamin D (s25OHD) concentrations and their effect on respiratory health in cystic fibrosis. SUBJECTS/METHODS: Sixteen CF patients were randomized to receive vitamin D2 or D3 or to serve as controls. The starting dose of 5000 IU (< 16 years old) or 7143 IU/day (>= 16 years old) was further individually adjusted. Three months of intervention were followed by two of washout (ClinicalTrials. gov NCT01321905). RESULTS: To increase s25OHD, the mean daily dose of vitamin D2 and D3 had to be increased up to 15650 and 8184 IU, respectively. The combined group of vitamin D2 and D3 treated patients decreased plasma IL-8 (P < 0.05). Patients provided vitamin D3 improved FVC at the end of the trial (P < 0.05). Change in s25OHD was positively correlated with changes in the adult Quality-of-Life respiratory score at the end of supplementation (P = 0.006, r = 0.90), and with changes in FEV1 (P = 0.042, r = 0.62) and FVC (P = 0.036, r = 0.63) at one month of washout. CONCLUSIONS: Vitamin D supplementation may contribute to reduced inflammation and improved lung function in CF
CFTR is involved in the regulation of glucagon secretion in human and rodent alpha cells
Glucagon is the main counterregulatory hormone in the body. Still, the mechanism involved in the regulation of glucagon secretion from pancreatic alpha cells remains elusive. Dysregulated glucagon secretion is common in patients with Cystic Fibrosis (CF) that develop CF related diabetes (CFRD). CF is caused by a mutation in the Cl(-) channel Cystic fibrosis transmembrane conductance regulator (CFTR), but whether CFTR is present in human alpha cells and regulate glucagon secretion has not been investigated in detail. Here, both human and mouse alpha cells showed CFTR protein expression, whereas CFTR was absent in somatostatin secreting delta cells. CFTR-current activity induced by cAMP was measured in single alpha cells. Glucagon secretion at different glucose levels and in the presence of forskolin was increased by CFTR-inhibition in human islets, whereas depolarization-induced glucagon secretion was unaffected. CFTR is suggested to mainly regulate the membrane potential through an intrinsic alpha cell effect, as supported by a mathematical model of alpha cell electrophysiology. In conclusion, CFTR channels are present in alpha cells and act as important negative regulators of cAMP-enhanced glucagon secretion through effects on alpha cell membrane potential. Our data support that loss-of-function mutations in CFTR contributes to dysregulated glucagon secretion in CFRD
The stromal cell–derived factor-1α/CXCR4 ligand–receptor axis is critical for progenitor survival and migration in the pancreas
The SDF-1α/CXCR4 ligand/chemokine receptor pair is required for appropriate patterning during ontogeny and stimulates the growth and differentiation of critical cell types. Here, we demonstrate SDF-1α and CXCR4 expression in fetal pancreas. We have found that SDF-1α and its receptor CXCR4 are expressed in islets, also CXCR4 is expressed in and around the proliferating duct epithelium of the regenerating pancreas of the interferon (IFN) γ–nonobese diabetic mouse. We show that SDF-1α stimulates the phosphorylation of Akt, mitogen-activated protein kinase, and Src in pancreatic duct cells. Furthermore, migration assays indicate a stimulatory effect of SDF-1α on ductal cell migration. Importantly, blocking the SDF-1α/CXCR4 axis in IFNγ-nonobese diabetic mice resulted in diminished proliferation and increased apoptosis in the pancreatic ductal cells. Together, these data indicate that the SDF-1α–CXCR4 ligand receptor axis is an obligatory component in the maintenance of duct cell survival, proliferation, and migration during pancreatic regeneration
The stromal cell-derived factor-1alpha/CXCR4 ligand-receptor axis is critical for progenitor survival and migration in the pancreas.
The SDF-1alpha/CXCR4 ligand/chemokine receptor pair is required for appropriate patterning during ontogeny and stimulates the growth and differentiation of critical cell types. Here, we demonstrate SDF-1alpha and CXCR4 expression in fetal pancreas. We have found that SDF-1alpha and its receptor CXCR4 are expressed in islets, also CXCR4 is expressed in and around the proliferating duct epithelium of the regenerating pancreas of the interferon (IFN) gamma-nonobese diabetic mouse. We show that SDF-1alpha stimulates the phosphorylation of Akt, mitogen-activated protein kinase, and Src in pancreatic duct cells. Furthermore, migration assays indicate a stimulatory effect of SDF-1alpha on ductal cell migration. Importantly, blocking the SDF-1alpha/CXCR4 axis in IFNgamma-nonobese diabetic mice resulted in diminished proliferation and increased apoptosis in the pancreatic ductal cells. Together, these data indicate that the SDF-1alpha-CXCR4 ligand receptor axis is an obligatory component in the maintenance of duct cell survival, proliferation, and migration during pancreatic regeneration
Coxsackievirus B Vaccines Prevent Infection-Accelerated Diabetes in NOD Mice and Have No Disease-Inducing Effect
Enteroviruses, including the Coxsackievirus Bs (CVB), have been implicated as causal agents in human type 1 diabetes. Immunization of at-risk individuals with a CVB vaccine provides an attractive strategy for elucidating the role of CVBs in the disease etiology. Previously, we have shown that an inactivated whole-virus vaccine covering all CVB serotypes (CVB1-6) is safe to administer and highly immunogenic in preclinical models, including nonhuman primates. Before initiating clinical trials with this type of vaccine, it was also important to address 1) whether the vaccine itself induces adverse immune reactions, including accelerating diabetes onset in a diabetes-prone host, and 2) whether the vaccine can prevent CVB-induced diabetes in a well-established disease model. Here, we present results from studies in which female NOD mice were left untreated, mock-vaccinated, or vaccinated with CVB1-6 vaccine and monitored for insulitis occurrence or diabetes development. We demonstrate that vaccination induces virus-neutralizing antibodies without altering insulitis scores or the onset of diabetes. We also show that NOD mice vaccinated with a CVB1 vaccine are protected from CVB-induced accelerated disease onset. Taken together, these studies show that CVB vaccines do not alter islet inflammation or accelerate disease progression in an animal model that spontaneously develops autoimmune type 1 diabetes. However, they can prevent CVB-mediated disease progression in the same model.acceptedVersionPeer reviewe
An IFIH1 gene polymorphism associated with risk for autoimmunity regulates canonical antiviral defence pathways in Coxsackievirus infected human pancreatic islets
The IFIH1 gene encodes the pattern recognition receptor MDA5. A common
polymorphism in IFIH1 (rs1990760, A946T) confers increased risk for
autoimmune disease, including type 1-diabetes (T1D). Coxsackievirus
infections are linked to T1D and cause beta-cell damage in vitro. Here
we demonstrate that the rs1990760 polymorphism regulates the interferon
(IFN) signature expressed by human pancreatic islets following
Coxsackievirus infection. A strong IFN signature was associated with
high expression of IFNλ1 and IFNλ2, linking rs1990760 to the expression
of type III IFNs. In the high-responding genotype, IRF-1 expression
correlated with that of type III IFN, suggesting a positive-feedback on
type III IFN transcription. In summary, our study uncovers an influence
of rs1990760 on the canonical effector function of MDA5 in response to
an acute infection of primary human parenchymal cells with a clinically
relevant virus linked to human T1D. It also highlights a previously
unrecognized connection between the rs1990760 polymorphism and the
expression level of type III IFNs.</p
Defining the proteolytic landscape during enterovirus infection.
Viruses cleave cellular proteins to remodel the host proteome. The study of these cleavages has revealed mechanisms of immune evasion, resource exploitation, and pathogenesis. However, the full extent of virus-induced proteolysis in infected cells is unknown, mainly because until recently the technology for a global view of proteolysis within cells was lacking. Here, we report the first comprehensive catalog of proteins cleaved upon enterovirus infection and identify the sites within proteins where the cleavages occur. We employed multiple strategies to confirm protein cleavages and assigned them to one of the two enteroviral proteases. Detailed characterization of one substrate, LSM14A, a p body protein with a role in antiviral immunity, showed that cleavage of this protein disrupts its antiviral function. This study yields a new depth of information about the host interface with a group of viruses that are both important biological tools and significant agents of disease
Structural Insight into CVB3-VLP Non-Adjuvanted Vaccine
Coxsackievirus B (CVB) enteroviruses are common pathogens that can cause acute and chronic myocarditis, dilated cardiomyopathy, aseptic meningitis, and they are hypothesized to be a causal factor in type 1 diabetes. The licensed enterovirus vaccines and those currently in clinical development are traditional inactivated or live attenuated vaccines. Even though these vaccines work well in the prevention of enterovirus diseases, new vaccine technologies, like virus-like particles (VLPs), can offer important advantages in the manufacturing and epitope engineering. We have previously produced VLPs for CVB3 and CVB1 in insect cells. Here, we describe the production of CVB3-VLPs with enhanced production yield and purity using an improved purification method consisting of tangential flow filtration and ion exchange chromatography, which is compatible with industrial scale production. We also resolved the CVB3-VLP structure by Cryo-Electron Microscopy imaging and single particle reconstruction. The VLP diameter is 30.9 nm on average, and it is similar to Coxsackievirus A VLPs and the expanded enterovirus cell-entry intermediate (the 135s particle), which is similar to 2 nm larger than the mature virion. High neutralizing and total IgG antibody levels, the latter being a predominantly Th2 type (IgG1) phenotype, were detected in C57BL/6J mice immunized with non-adjuvanted CVB3-VLP vaccine. The structural and immunogenic data presented here indicate the potential of this improved methodology to produce highly immunogenic enterovirus VLP-vaccines in the future.Peer reviewe
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