Double-Stranded DNA Activates Glomerular Endothelial Cells and Enhances Albumin Permeability via a Toll-Like Receptor-Independent Cytosolic DNA Recognition Pathway

Abstract

Viral DNA induces potent antiviral immunity by activating dendritic cells; however, the mechanism governing viral DNA-mediated triggering or aggravation of glomerulonephritis is unknown. Glomerular endothelial cells (GEnCs) do not express toll-like receptor (TLR)9, the only DNA-specific TLR. We therefore hypothesized that DNA could activate GEnCs via the recently discovered TLR-independent viral DNA recognition pathway. Indeed, double-stranded non-CpG (B-) DNA activated GEnCs to produce interleukin-6, CCL5/RANTES, CCL2/ MCP-1, CXCL10/IP10, interferon (IFN)-␣, and IFN-␤ when cationic lipids facilitated intracellular DNA uptake. This cytokine production was inhibited by chlorpromazine , suggesting that clathrin-dependent endocytosis is required for B-DNA entry. However , chloroquine and MyD88 inhibition did not affect GEnC activation, suggesting TLR-independent DNA recognition. In addition, IFN-␤ activated cytokine and chemokine mRNA expression, although only CXCL10/IP10 was induced at the protein level, and type I IFN did not activate GEnC in an autocrine-paracrine auto-activation loop. B-DNA complexes induced intercellular adhesion molecule-1 expression at the GEnC surface and increased intercellular adhesion molecule-1-dependent leukocyte adhesion and microvascular extravasation in vivo. Furthermore, B-DNA complexes increased albumin permeability of GEnC monolayers in culture or microvascular dextran leakage in vivo. In addition, B-DNA complexes impaired GEnC proliferation. Thus, complexed B-DNA activates GEnC to produce cytokines, chemokines , and type I IFNs , increases leukocyte adhesion and microvascular permeability , and reduces GEnC proliferation via a MyD88-independent cytosolic DNA recognition pathway. This innate antiviral response program suggests a novel pathomechanism regulating DNA virus-mediated induction or aggravation of glomerulonephritis.

Interferon-γ and Granulocyte/Monocyte Colony-stimulating Factor Production by Natural Killer Cells Involves Different Signaling Pathways and the Adaptor Stimulator of Interferon Genes (STING)

“…Finally, we found that STING and CpG-ODN overlapped in NK cells. This result is consistent with the observation by Hagele et al (33) that DNA oligonucleotides present in endosomes may reach the cytoplasm. The existence of STING as an alternative cytosolic sensor for bacterial DNA may be an advantage for the detection of intracytoplasmic bacteria.…”

Histones from Dying Renal Cells Aggravate Kidney Injury via TLR2 and TLR4

“…From measured vessel diameters and centerline blood flow velocity, apparent wall shear stress was calculated, assuming a parabolic flow velocity profile over the vessel cross section. 51 As a measure of microvascular permeability, five postcapillary vessel segments as well as the surrounding perivascular tissue were excited at 488 nm, and emission .515 nm was recorded by a CCD camera (Sensicam, PCO, Kelheim, Germany) 30 minutes after injection of FITC-dextran (Sigma Aldrich) using an appropriate emission filter (LP 515). Mean gray values of fluorescence intensity were measured by digital image analysis (TILLvisION 4.0, TILL Photonics) in six randomly selected regions of interest (50350 mm 2 ), localized approximately 50 mm distant from the venule under investigation.…”

Cathepsin S Cleavage of Protease-Activated Receptor-2 on Endothelial Cells Promotes Microvascular Diabetes Complications

“…The transwell permeability of FITC-conjugated albumin in GEnC monolayer was performed as described. 50 Reactive oxygen species production in cultured GEnCs was determined using the electron spin resonance method. In brief, confluent GEnCs were stimulated with Cat-S with or without inhibitors in serum-free RPMI media.…”