Guanylate-binding protein-5 is involved in inflammasome activation by bacterial DNA but only the cooperation of multiple GBPs accounts for control of Brucella abortus infection

Author(s)

Marinho, Fabio V. ; Brito, Camila ; de Araujo, Ana Carolina V. S. C. ; Oliveira, Sergio C.

• Document type: Journal article
• Source: FRONTIERS IN IMMUNOLOGY; v. 15, p. 12-pg., 2024-02-08.

Abstract

Introduction: Guanylate-binding proteins (GBPs) are produced in response to pro-inflammatory signals, mainly interferons. The most studied cluster of GBPs in mice is on chromosome 3. It comprises the genes for GBP1-to-3, GBP5 and GBP7. In humans, all GBPs are present in a single cluster on chromosome 1. Brucella abortus is a Gram-negative bacterium known to cause brucellosis, a debilitating disease that affects both humans and animals. Our group demonstrated previously that GBPs present on murine chromosome 3 (GBPchr3) is important to disrupt Brucella-containing vacuole and GBP5 itself is important to Brucella intracellular LPS recognition. In this work, we investigated further the role of GBPs during B. abortus infection. Methods and results: We observed that all GBPs from murine chromosome 3 are significantly upregulated in response to B. abortus infection in mouse bone marrow-derived macrophages. Of note, GBP5 presents the highest expression level in all time points evaluated. However, only GBPchr3-/- cells presented increased bacterial burden compared to wild-type macrophages. Brucella DNA is an important Pathogen-Associated Molecular Pattern that could be available for inflammasome activation after BCV disruption mediated by GBPs. In this regard, we observed reduced IL-1 beta production in the absence of GBP2 or GBP5, as well as in GBPchr3-/- murine macrophages. Similar result was showed by THP-1 macrophages with downregulation of GBP2 and GBP5 mediated by siRNA. Furthermore, significant reduction on caspase-1 p20 levels, LDH release and Gasdermin-D conversion into its mature form (p30 N-terminal subunit) was observed only in GBPchr3-/- macrophages. In an in vivo perspective, we found that GBPchr3-/- mice had increased B. abortus burden and higher number of granulomas per area of liver tissue, indicating increased disease severity. Discussion/conclusion: Altogether, these results demonstrate that although GBP5 presents a high expression pattern and is involved in inflammasome activation by bacterial DNA in macrophages, the cooperation of multiple GBPs from murine chromosome 3 is necessary for full control of Brucella abortus infection. (AU)

• FAPESP's process: 22/15358-7 - The role of STING and the unfolded protein response on macrophage polarization and control of Brucella abortus infection
• Grantee: Sergio Costa Oliveira
• Support Opportunities: Regular Research Grants
• FAPESP's process: 23/02577-5 - Study of the mechanisms responsible for trained immunity induced by Bacillus Calmette-Guérin (BCG) in infectious diseases and Cancer
• Grantee: Sergio Costa Oliveira
• Support Opportunities: Research Projects - Thematic Grants
• FAPESP's process: 23/09226-3 - Unraveling trained immune mechanisms mediated by BCG in macrophages and dendritic cells during infection by the intracellular bacterium Brucella abortus
• Grantee: Ana Carolina Valente Santos Cruz de Araujo
• Support Opportunities: Scholarships in Brazil - Post-Doctoral