Antiviral and myocyte protective effects of IL-28A in coxsackievirus B3-induced myocarditis

Objective: This study aimed to investigate whether interleukin-28A (IL-28A) plays a role in murine myocarditis induced by coxsackievirus B3 (CVB3), and to explore its possible mechanism involved. Methods: Male BALB/c mice both infected and not infected by CVB3 were randomly divided into four groups (n = 40), untreated or treated with different doses of IL-28A for 4 days, and then sacrificed on days 4 and 7 post-infection. The heart samples were collected for histopathologic examination. Cardiac viral load was determined by a plaque assay. Additionally, immunoblot analysis, TUNEL assay, and immunohistochemistry were performed to examine the expression of signal transducer, activator of transcription 1 and 2 (STAT1 and STAT2), CVB3-induced apoptosis and the expression of Bcl-2, BAX and Caspase-3. Results: Compared to uninfected mice, the CVB3 infected mice exhibited higher mortality rate (p < 0.001), apparent inflammation and myocardial lesion (p < 0.01), and higher cardiac viral load (p < 0.01). After CVB3 infection, IL-28A treated mice presented no death (p < 0.001), reduced inflammation and myocardial lesion (p < 0.01), and lower viral load (p < 0.01) compared to untreated mice. Besides, treatment with IL-28A markedly increased the expressions of STAT1 and STAT2, and inhibited CVB3-induced apoptosis in myocardial cells with increased ratio of Bcl-2/BAX. Conclusion: The antiviral and myocyte protective effects of IL-28A in CVB3-inducedmyocarditis are regulated by STAT1 and STAT2. .

Simvastatin acts as an inhibitor of interferon gamma-induced cycloxygenase-2 expression in human THP-1 cells, but not in murine RAW264.7 cell

Cyclooxygenase-2 (COX-2) is a key inflammatory response molecule, and associated with many immune functions of monocytes/macrophages. Particularly, interferon gamma (IFNgamma)-induced COX-2 expression appears in inflammatory conditions such as viral infection and autoimmune diseases. Recently, statins have been reported to show variable effects on COX-2 expression, and on their cell and species type dependences. Based on the above description, we compared the effect of simvastatin on IFNgamma-induced COX-2 expression in human monocytes versus murine macrophages. In a result, we found that simvastatin suppresses IFNgamma-induced COX-2 expression in human THP-1 monocytes, but rather, potentiates IFNgamma-induced COX-2 expression in murine RAW264.7 macrophages. However, signal transducer and activator of transcriptio n 1/3 (STAT1/3), known as a transcription factor on COX-2 expression, is inactivated by simvastatin in both cells. Our findings showed that simvastatin is likely to suppress IFNgamma-induced COX-2 expression by inhibiting STAT1/3 activation in human THP-1 cells, but not in murine RAW264.7 cells. Thus, we concluded that IFNgamma-induced COX-2 expression is differently regulated by simvastatin depending on species specific mechanism.

Epithelial cell signaling responses to enterohemorrhagic Escherichia coli infection

Enterohemorrhagic Escherichia coli, including the serotype O157:H7 that is most commonly identified with human disease, cause both sporadic cases and outbreaks of non-bloody diarrhea and hemorrhagic colitis. In about 10 percent of infected subjects, the hemolytic uremic syndrome (hemolytic anemic, thrombocytopenia, and acute renal failure) develops, likely as a consequence of systemic spread of bacterial-derived toxins variously referred to as Shiga-like toxin, Shiga toxin, and Verotoxin. Increasing evidence points to a complex interplay between bacterial products - for example, adhesins and toxins - and host signal transduction pathways in mediating responses to infection. Identification of critical signaling pathways could result in the development of novel strategies for intervention to both prevent and treat this microbial infection in humans.