Biology subjects

Matsunaga, J.

Publications and source records attributed to Matsunaga, J..

2 recordsLinked to original sources

bioRxiv2025

cGAS-STING dependent type I IFN protects against Leptospira interrogans renal colonization in mice.

Leptospira interrogans is the major causative agent of leptospirosis. Humans, canines and livestock animals are susceptible to Leptospira species and can develop fulminant disease. Rodents serve as reservoir hosts in which the bacteria colonize the renal tubules and are excreted in the urine. The host immune response to Leptospira spp. remains poorly defined. We show that L. interrogans induces a robust type I interferon (IFN) response in human and murine macrophages that is dependent on the cytosolic dsDNA sensor Cyclic GMP-AMP Synthase (cGAS) and the Stimulator of IFN Genes (STING) signaling pathway. Further, we show that mice deficient in the IFN/{beta} receptor subunit 1 (IFNAR1) or STING had higher bacterial burdens and increased renal colonization following infection in vivo suggesting that cGAS-STING-driven type I IFN is required for the host defense against L. interrogans. These findings demonstrate the significance of cGAS-STING-dependent type I IFN signaling in mammalian innate immune responses to L. interrogans. Author SummaryLeptospirosis is a globally distributed zoonotic disease caused by spirochetes belonging to the genus Leptospira. While humans, livestock, and dogs can develop severe or even fatal illness upon infection, rodents typically serve as asymptomatic reservoir hosts. A defining feature of the leptospiral life cycle is the ability of the pathogen to colonize the kidney in these reservoir host species, leading to prolonged urinary shedding and environmental dissemination. Despite the significant global burden of leptospirosis, the innate immune pathways that detect this pathogen and prevent renal colonization remain poorly understood. In this study we demonstrate that L. interrogans induces a robust type I IFN cytokine response from macrophages. The induction of this type I IFN response is dependent on sensing cytosolic DNA by the cGAS-STING pathway. Using in vivo mouse models of L. interrogans infection we further show that activation of this pathway is required to control bacterial burdens and reduce long-term kidney colonization. This study is the first to demonstrate a critical role for cGAS-STING and type I IFN in controlling L. interrogans infection.

immunology↗

bioRxiv2018

Identification of a cis-acting determinant limiting expression of sphingomyelinase gene sph2 in Leptospira interrogans with a gfp reporter plasmid

Many Pomona strains of the spirochete Leptospira interrogans express the osmotically-inducible sphingomyelinase gene, sph2, at much higher levels than non-Pomona strains. We developed a new green fluorescent protein (GFP) reporter plasmid to examine sph2 gene expression determinants. The vector allows fusion of the test promoter to the ribosome-binding site and coding region of gfp. We fused the sph2 promoters from the serovar Lai strain 56601 and from the serovar Pomona strain LC82-25 to gfp to examine the molecular determinants of differential sph2 expression between the two strains. Similar to what is observed with the native sph2 genes, introduction of the plasmids into the Lai 56601 strain resulted in near background levels of gfp expression from the Lai sph2 promoter, while expression from the Pomona sph2 promoter was high. Expression from both fusions increased at physiologic levels of osmolarity achieved by addition of sodium chloride to the culture medium. We examined the role of a 17 bp upstream element found in all L. interrogans strains expressing low basal levels of sph2 and missing from Pomona strains that express sph2 at high levels. When the 17 bp sequence present upstream of the Lai sph2 promoter was deleted or scrambled, fusion expression increased substantially. Conversely, insertion of the 17 bp sequence upstream of the Pomona sph2 promoter diminished fusion expression. In contrast, removal of an insertion sequence-like element that is found only in the Pomona sph2 upstream sequence had no effect on expression from the Pomona sph2 fusion in the Lai strain. These findings demonstrate the utility of the gfp reporter plasmid in analyzing gene expression in L. interrogans.\n\nIMPORTANCE\n\nGenetic tools are needed to examine gene expression in the pathogen Leptospira interrogans. We developed a reporter plasmid that replicates in L. interrogans with green fluorescent protein (GFP) as the read out of promoter activity. We demonstrated an application of the new reporter plasmid by identifying an upstream element responsible for the poor basal expression of the sph2 sphingomyelinase gene in a serovar Lai strain of L. interrogans. This new tool is useful for discovery of the molecular determinants of L. interrogans gene expression.

microbiology↗