The effect of bile duct ligation on the intercellular junctions of hepatocytes was investigated. The features and the arrangement of the bile canaliculi and the zonulae occludentes alter concomitant to the increase of the intracanalicular pressure. The lumen of the bile canaliculi enlarges and the microvilli disappear. The array of the zonulae occludentes becomes irregularly shaped, the number of strands diminishes and interruptions of the strands occur. With peroxidase a leakage in the bile-blood barrier is detected. Furthermore a disappearance of gap junctions between the hepatocytes after bile duct ligation is observed. The present investigation shows that the zonulae occludentes are mobile structures which are changed by increased unilateral pressure. Due to their ultrastructural alterations, a leakage of the permeability barrier between physiological compartments is found.

RIG-I recognizes viral dsRNA and activates a cell-autonomous antiviral response. Upon stimulation, it triggers a signaling cascade leading to the production of type I and III IFNs. IFNs are secreted and signal to elicit the expression of IFN-stimulated genes, establishing an antiviral state of the cell. The topology of this pathway has been studied intensively, however, its exact dynamics are less understood. Here, we employed electroporation to synchronously activate RIG-I, enabling us to characterize cell-intrinsic innate immune signaling at a high temporal resolution. Employing IFNAR1/IFNLR-deficient cells, we could differentiate primary RIG-I signaling from secondary signaling downstream of the IFN receptors. Based on these data, we developed a comprehensive mathematical model capable of simulating signaling downstream of dsRNA recognition by RIG-I and the feedback and signal amplification by IFN. We further investigated the impact of viral antagonists on signaling dynamics. Our work provides a comprehensive insight into the signaling events that occur early upon virus infection and opens new avenues to study and disentangle the complexity of the host–virus interface.

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