Inflammasomes and anti-viral immunity
ABSTRACT Type I Interferons are the hallmark cytokines deployed during infection to combat invading viruses. However, inflammatory cytokines such as Interleukin (IL)-1beta and IL-18 also play important roles in anti-viral defenses. The activity of IL-1beta and IL18 are regulated at the level of expression, processing, and secretion. Several classes of innate immune receptors control the expression of these cytokines, which must then be proteolytically processed via caspase-1. In this review, we provide an overview of how caspase-1-activating inflammasomes participate during viral infections and their role in regulating anti-viral immunity.
- SourceAvailable from: Monica Imarai
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- "importance of IL-1b (and IL-18) in anti-viral defenses that are supported by the enhanced susceptibility of mice lacking the cytokine receptors to virus infection . Therefore, during salmon IPNV infection, lack of induction of IL-1b and IL-8 expression in the immune organs may actually weaken anti-viral activity and impair resolution of the infection. "
ABSTRACT: IPNV is the agent of a well-characterized acute disease that produces a systemic infection and high mortality in farmed fish species and persistent infection in surviving fish after outbreaks. Because modulation of the host expression of pro and anti-inflammatory cytokines can help establish persistence, in this study, we examined the expression of IL-1β, IL-8, IFNα1 and IL-10 during acute and persistent IPNV infection of Atlantic salmon. Results showed that IPNV infection induces an increase of the IFNα1 and IL-10 mRNA levels in the spleen and head kidney (HK) of fish after acute experimental infection. Levels of the pro-inflammatory cytokines IL-1β and IL-8 did not rise in the spleen although an increase of IL-1β, but not of IL-8, was observed in head kidney. In carrier asymptomatic salmon, cytokine gene expression of IFNα1 in the spleen and IL-10 in head kidney were also significantly higher than expression in non-carrier fish. Interestingly, a decrease of IL-8 expression was also observed. IPNV infection of SHK-1, which is a macrophage-like cell line of salmon, also induced an increase of expression of the anti-inflammatory cytokine IL-10 with no effects on the expression of IL-1β and IL-8. The effects are induced by an unknown mechanism during viral infection because poly I:C and the viral genomic dsRNA showed the opposite effects on cytokine expression in SHK-1 cells. In summary, IPNV always induces up-regulation of the anti-inflammatory cytokine IL-10 in Atlantic salmon. As this is accompanied by a lack of induction of the pro-inflammatory cytokines IL-1β and IL-8, the anti-inflammatory milieu may explain the high frequency, prevalence and persistence of IPNV in salmon. Effects might be part of the viral mechanisms of immune evasion.Fish & Shellfish Immunology 11/2011; 32(2):291-300. DOI:10.1016/j.fsi.2011.11.018 · 3.03 Impact Factor
Article: Innate immune sensing of DNA viruses[Show abstract] [Hide abstract]
ABSTRACT: DNA viruses are a significant contributor to human morbidity and mortality. The immune system protects against viral infections through coordinated innate and adaptive immune responses. While the antigen-specific adaptive mechanisms have been extensively studied, the critical contributions of innate immunity to anti-viral defenses have only been revealed in the very recent past. Central to these anti-viral defenses is the recognition of viral pathogens by a diverse set of germ-line encoded receptors that survey nearly all cellular compartments for the presence of pathogens. In this review, we discuss the recent advances in the innate immune sensing of DNA viruses and focus on the recognition mechanisms involved.Virology 02/2011; 411(2):153-62. DOI:10.1016/j.virol.2011.02.003 · 3.28 Impact Factor