Human RNase3 immune modulation by catalytic-dependent and independent modes in a macrophage-cell line infection model

Abstract

The human RNase3 is a member of the RNaseA superfamily involved in host immunity. RNase3 is expressed by leukocytes and shows broad-spectrum antimicrobial activity. Together with a direct antimicrobial action, RNase3 exhibits immunomodulatory properties. Here, we have analysed the transcriptome of macrophages exposed to the wild-type protein and a catalytic-defective mutant (RNase3-H15A). The analysis of differently expressed genes (DEGs) in treated THP1-derived macrophages highlighted a common pro-inflammatory “core-response” independent of the protein ribonucleolytic activity. Network analysis identified the epidermal growth factor receptor (EGFR) as the main central regulatory protein. Expression of selected DEGs and MAPK phosphorylation were inhibited by an anti-EGFR antibody. Structural analysis suggested that RNase3 activates the EGFR pathway by direct interaction with the receptor. Besides, we identified a subset of DEGs related to the protein ribonucleolytic activity, characteristic of virus infection response. Transcriptome analysis revealed an early pro-inflammatory response, not associated to the protein catalytic activity, followed by a late activation in a ribonucleolytic-dependent manner. Next, we demonstrated that overexpression of macrophage endogenous RNase3 protects the cells against infection by Mycobacterium aurum and the human respiratory syncytial virus. Comparison of cell infection profiles in the presence of Erlotinib, an EGFR inhibitor, revealed that the receptor activation is required for the antibacterial but not for the antiviral protein action. Moreover, the DEGs related and unrelated to the protein catalytic activity are associated to the immune response to bacterial and viral infection, respectively. We conclude that RNase3 modulates the macrophage defence against infection in both catalytic-dependent and independent manners.

Host Defence RNases as Antiviral Agents against Enveloped Single Stranded RNA Viruses

“…• Autophagy (in MEFs) VSV Y - [247] • Cleaves viral genomic RNA (in vitro) WNV Y + [276,277] • that the protein antiviral properties are associated with its catalytic activity [209]. On the other hand, increasing levels of ECP are found during HIV infection in both adults and children [210,211].…”

“…Very recently, we have demonstrated the antiviral activity against RSV of RNase 3 expressed in macrophages. Besides, a comparative transcriptome analysis indicates that the protein antiviral properties are associated with its catalytic activity[ 209 ]. On the other hand, increasing levels of ECP are found during HIV infection in both adults and children [ 210 , 211 ].…”

Structure-Based Design of an RNase Chimera for Antimicrobial Therapy

“…The antibacterial activity of RNases seems to be unrelated to their ability to degrade RNA [ 11 , 12 , 13 , 14 ]. However, recent work is showing that catalytic activity has a role in several aspects of the immune system properties of RNase proteins [ 15 , 16 , 17 ]. For example, the antiviral and fungicidal activities of RNases seem to be related to the RNase activity [ 18 , 19 ].…”

Selective cleavage of ncRNA and antiviral activity by human RNase2/EDN in a macrophage infection model

“…RSV infection activated the expression of RNase2 in macrophages RSV virus stock was obtained at a titration of 2.8×10 6 TCID50/mL, as previously described [25] and THP1 macrophages were exposed to the RSV at a selected MOI of 1:1 up to 72h post of infection (poi). Following, we examined whether RSV infection induced the RNase2 expression in THP1-derived macrophages.…”