Aims
The coxsackievirus B3 (CVB3) mouse myocarditis model is the standard model for investigation of virus-induced myocarditis but the pancreas, rather than the heart, is the most susceptible organ in mouse. The aim of this study was to develop a CVB3 mouse myocarditis model in which animals develop myocarditis while attenuating viral infection of the pancreas and the development of severe pancreatitis.
Methods and results
We developed the recombinant CVB3 variant H3N-375TS by inserting target sites (TS) of miR-375, which is specifically expressed in the pancreas, into the 3ʹUTR of the genome of the pancreo- and cardiotropic CVB3 variant H3. In vitro evaluation showed that H3N-375TS was suppressed in pancreatic miR-375-expressing EndoC-βH1 cells >5 log10, whereas its replication was not suppressed in isolated primary embryonic mouse cardiomyocytes. In vivo, intraperitoneal (i.p.) administration of H3N-375TS to NMRI mice did not result in pancreatic or cardiac infection. In contrast, intravenous (i.v.) administration of H3N-375TS to NMRI and Balb/C mice resulted in myocardial infection and acute and chronic myocarditis, whereas the virus was not detected in the pancreas and the pancreatic tissue was not damaged. Acute myocarditis was characterized by myocardial injury, inflammation with mononuclear cells, induction of proinflammatory cytokines, and detection of replicating H3N-375TS in the heart. Mice with chronic myocarditis showed myocardial fibrosis and persistence of H3N-375TS genomic RNA but no replicating virus in the heart. Moreover, H3N-375TS infected mice showed distinctly less suffering compared with mice that developed pancreatitis and myocarditis after i.p. or i.v application of control virus.
Conclusion
In this study, we demonstrate that by use of the miR-375-sensitive CVB3 variant H3N-375TS, CVB3 myocarditis can be established without the animals developing severe systemic infection and pancreatitis. As the H3N-375TS myocarditis model depends on pancreas-attenuated H3N-375TS, it can easily be used in different mouse strains and for various applications.
Cerebrovascular abnormality is frequently accompanied by cognitive dysfunctions, such as dementia. Antibodies against the α1 -adrenoceptor (α1 -AR) can be found in patients with Alzheimer's disease with cerebrovascular disease, and have been shown to affect the larger vessels of the brain in rodents. However, the impact of α1 -AR antibodies on the cerebral vasculature remains unclear. In the present study, we established a neuroimaging method to measure the relative cerebral blood volume (rCBV) in small rodents with the ultimate goal to detect changes in blood vessel density and/or vessel size induced by α1 -AR antibodies. For this purpose, mapping of R2 * and R2 was performed using MRI at 9.4 T, before and after the injection of intravascular iron oxide particles (ferumoxytol). The change in the transverse relaxation rates (ΔR2 *, ΔR2 ) showed a significant rCBV decrease in the cerebrum, cortex and hippocampus of rats (except hippocampal ΔR2 ), which was more pronounced for ΔR2 * than for ΔR2 . Immunohistological analyses confirmed that the α1 -AR antibody induced blood vessel deficiencies. Our findings support the hypothesis that α1 -AR antibodies lead to cerebral vessel damage throughout the brain, which can be monitored by MRI-derived rCBV, a non-invasive neuroimaging method. This demonstrates the value of rCBV estimation by ferumoxytol-enhanced MRI at 9.4 T, and further underlines the significance of this antibody in brain diseases involving vasculature impairments, such as dementia.
Coxsackievirus B3 (CVB3) has potential as a new oncolytic agent for the treatment of cancer but can induce severe pancreatitis. Here, we inserted target sequences of the microRNA miR‐375 (miR‐375TS) into the 5′ terminus of the polyprotein encoding sequence or into the 3′UTR of the CVB3 strain rCVB3.1 to prevent viral replication in the pancreas. In pancreatic EndoC‐βH1 cells expressing miR‐375 endogenously, replication of the 5′‐miR‐375TS virus and that of the 3′‐miR‐375TS virus was reduced by 4 × 103‐fold and 3.9 × 104‐fold, respectively, compared to the parental rCVB3.1. In colorectal carcinoma cells, replication and cytotoxicity of both viruses were slightly reduced compared to rCVB3.1, but less pronounced for the 3′‐miR‐375TS virus. Thus, CVB3 with miR‐375TS in the 3′UTR of the viral genome may be suitable to avoid pancreatic toxicity.
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