Zika fever, a mosquito-borne infectious disease caused by Zika virus (ZIKV), is an epidemic disease for which no effective therapy has been established. The recent outbreaks of ZIKV in Brazil and French Polynesia have been linked to a considerable increase in the incidence of fetal microcephaly and other diseases such as Guillain-Barre syndrome. Because there is currently no specific therapy or vaccine, the early exploitation of a method to prevent expansion of ZIKV is a high priority. To validate commonly used antiviral drugs, we evaluated the effect of ribavirin, a drug used to treat hepatitis C with interferon-β (IFN-β), on ZIKV replication. In mammalian cells, we observed an inhibitory effect of ribavirin on ZIKV replication and ZIKV-induced cell death without cytotoxic effect. Furthermore, we found that STAT1-deficient mice, which lack type I IFN signaling, were highly sensitive to ZIKV infection and exhibited lethal outcome. Ribavirin abrogated viremia in ZIKV-infected STAT-1-deficient mice. These data suggest that the inhibition of viral RNA-dependent RNA polymerases may be effective for treatment of ZIKV infection. Our data provide a new insight into the mechanisms for inhibition of ZIKV replication and prevention of Zika fever.
Chikungunya fever is a mosquito‐borne disease cause of persistent arthralgia. The current diagnosis of Chikungunya virus (CHIKV) relies on a conventional reverse transcription polymerase chain reaction assay. Reverse transcription loop‐mediated isothermal amplification (RT‐LAMP) is a rapid and simple tool used for DNA‐based diagnosis of a variety of infectious diseases. In this study, we established an RT‐LAMP system to recognize CHIKV by targeting the envelope protein 1 (E1) gene that could also detect CHIKV at a concentration of 8 PFU without incorrectly detecting other mosquito‐borne viruses. The system also amplified the E1 genome in the serum of CHIKV‐infected mice with high sensitivity and specificity. Moreover, we established a dry RT‐LAMP system that can be transported without a cold chain, which detected the virus genome in CHIKV‐infected patient samples with high accuracy. Thus, the dry RT‐LAMP system has great potential to be applied as a novel CHIKV screening kit in endemic areas.
Antibiotics sometimes exert adverse effects on the pathogenesis of colitis due to the dysbiosis resulting from the disruption of gut homeostasis. However, the precise mechanisms underlying colitogenic effects of antibiotic‐induced colitis are largely unknown. Here, we show a novel murine fecal occult bleeding model induced by the combinatorial treatment of ampicillin and vancomycin, which is accompanied by an enlarged cecum, upregulation of pro‐inflammatory cytokines IL‐6 and IL‐12, a reduction in Ki‐67‐positive epithelial cell number and an increase in the apoptotic cell number in the colon. Moreover, gas chromatography–tandem mass analysis showed that various kinds of metabolites, including glutamic acid and butyric acid, were significantly decreased in the cecal contents. In addition, abundance of butyric acid producer Clostridiales was dramatically reduced in the enlarged cecum. Interestingly, supplementation of monosodium glutamate or its precursor glutamine suppressed colonic IL‐6 and IL‐12, protected from cell apoptosis and prevented fecal occult blood indicating that the reduced level of glutamic acid is a possible mechanism of antibiotic‐induced fecal occult bleeding. Our data showed a novel mechanism of antibiotic‐induced fecal occult bleeding providing a new insight into the clinical application of glutamic acid for the treatment of antibiotic‐induced colitis.
Inflammatory bowel disease (IBD) is a chronic inflammatory disorder in the intestine, and the dysfunction of intestinal epithelial barrier (IEB) may trigger the onset of IBD. Secretory leukocyte protease inhibitor (SLPI) is a serine protease inhibitor that has been implicated in the tissue‐protective effect in the skin and lung. We found that SLPI was induced in lipopolysaccharides‐treated colon carcinoma cell line and in the colon of dextran sulfate sodium (DSS)‐treated mice. SLPI‐deficient mice were administered DSS to induce colitis and sustained severe inflammation compared with wild‐type mice. The colonic mucosa of SLPI‐deficient mice showed more severe inflammation with neutrophil infiltration and higher levels of proinflammatory cytokines compared with control mice. Moreover, neutrophil elastase (NE) activity in SLPI‐deficient mice was increased and IEB function was severely impaired in the colon, accompanied with the increased number of apoptotic cells. Importantly, we demonstrated that DSS‐induced colitis was ameliorated by administration of protease inhibitor SSR69071 and recombinant SLPI. These results suggest that the protease inhibitory activity of SLPI protects from colitis by preventing IEB dysfunction caused by excessive NE activity, which provides insight into the novel function of SLPI in the regulation of gut homeostasis and therapeutic approaches for IBD.
Background: Both environmental and genetic factors have been implicated in the induction of autoimmune disease. Therefore, it is important to understand the pathophysiological significance of the gut microbiota and host genetic background that contribute to an autoimmune disease such as inflammatory bowel disease (IBD). We have previously reported that mice deficient for suppressor of cytokine signaling-1 (SOCS1), in which SOCS1 expression was restored in T and B cells on an SOCS1–/– background (SOCS1–/–Tg mice), developed systemic autoimmune diseases accompanied by spontaneous colitis. Methods: To investigate whether the proinflammatory genetic background affects the gut microbiota, we used SOCS1–/–Tg mice as a model of spontaneous chronic colitis. Fecal samples were collected from SOCS1–/–Tg mice and SOCS1+/+Tg (control) mice at 1 and 6 months of age, and the fecal bacterial 16S ribosomal RNA genes were sequenced using the Illumina MiSeq platform. Results: Gut microbial diversity was significantly reduced and the intestinal bacterial community composition changed in SOCS1–/–Tg mice in comparison with the control mice. Interestingly, the population of Prevotella species, which is known to be elevated in ulcerative colitis and colorectal cancer patients, was significantly increased in SOCS1–/–Tg mice regardless of age. Conclusion: Taken together, these results suggest that the proinflammatory genetic background owing to SOCS1 deficiency causes dysbiosis of the gut microbiota, which in turn generates a procolitogenic environment.
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