Sorafenib suppresses the activation of type I interferon pathway induced by RLR-MAVS and cGAS-STING signaling.

Type I interferon pathway is a crucial component of innate immune signaling upon pathogen infection or endogenous instability. An imbalance of type I interferon can lead to many diseases, such as autoimmune diseases and inflammatory diseases. Meanwhile, the side effects of clinical drugs on type I interferon signaling may result in impaired outcomes in clinical treatment, especially in cancer immunotherapy which is associated with type I interferon signaling. Here, we found that sorafenib, an FDA-approved drug for HCC chemotherapy, suppresses both DNA- and RNA-sensing mediated type I interferon pathway. Mechanistically, sorafenib treatment induces the autophagic degradation of MAVS, cGAS, TBK1, and IRF3, and attenuates the signaling transduction. In addition, sorafenib also inhibits the recruiting of STING or MAVS with TBK1 and IRF3. This work reveals the negative role of sorafenib in the regulation of type I interferon pathway. Sorafenib treatment is not only a potential drug for autoimmune disease and inflammation diseases, but also needs to be noticed in HCC chemotherapy.

Characterization of three novel cell lines derived from the brain of spotted sea bass: Focusing on cell markers and susceptibility toward iridoviruses.

Despite tens of cell lines originating from fish brain tissue have been constructed, little is known about the definite cell types they belong to. Whether fish cell lines derived from the brain shares similar characteristics is not well-answered yet. Here, we constructed three cell lines designated as LMB-S, LMB-M, LMB-L using brain tissue of spotted sea bass (Lateolabrax maculatus). Among them, LMB-L was identified as astroglia-like cells considering the high expression of GFAP, DCX, PTX, S100b, which are regarded as astrocyte-specific or astrocyte-associated cell markers. LMB-M exhibited smooth muscle-like features showing strong expression of LMOD1, SLAMP, M-cadherin, MGP, which are confirmed as muscle-restricted or myogenesis-involved cell markers. Although LMB-S was not definitely identified, it appeared an activation of WNT/ß-catenin pathway. Besides the distinct expression profiles of cell markers, the three cell lines also presented differences in transfection efficiency and susceptibility to iridovirus infection. Relying on the established cell lines, a novel megalocytivirus, named LMIV (Lateolabrax maculatus iridovirus), was first isolated from diseased spotted sea bass. Genetic analysis of major capsid protein (MCP) and adenosine triphosphatase (ATPase) manifested that LMIV was clearly distinguishable from other representative teleost iridoviruses. Further investigations revealed that LMIV could replicate most efficiently in LMB-L cells obtaining the highest viral load (2.16 × 1010 copy/mL). By contrast, LMB-S cells gave rise to the highest viral load up to 3.86 × 108 copy/mL, when the three cell lines were infected with MRV, a newly emerged ranavirus. Moreover, LMIV infection caused lots of cells to be detached from monolayers, generating adherent and non-adherent cells. An opposite expression profiling of type I IFN pathway-related genes (JAK1, STAT1, STAT2, IRF9, Mx1) was found between adherent and non-adherent cells. Combined with the analysis of MCP gene expression, it is speculated that inhibiting type I IFN pathway in non-adherent cells allowed the facilitation of virus duplication. Taken together, the present study broadens our understanding about the diversity of cell lines derived from fish brain tissue and screening cells more susceptible to virus is not only meaningful for the development of vaccine, but also provide clues for further clarification of cell-iridovirus interactions.