Biology subjects

Snyder, J. M.

Publications and source records attributed to Snyder, J. M..

3 recordsLinked to original sources

bioRxiv2020

PKR and the Integrated Stress Response drive immunopathology caused by ADAR1 mutation

Mutations in ADAR, the gene that encodes the ADAR1 RNA deaminase, cause numerous human diseases, including Aicardi-Goutieres Syndrome (AGS). ADAR1 is an essential negative regulator of the RNA sensor MDA5, and loss of ADAR1 function triggers inappropriate activation of MDA5 by self-RNAs. However, the mechanisms of MDA5-dependent disease pathogenesis in vivo remain unknown. Here, we introduce a knockin mouse that models the most common ADAR AGS mutation in humans. These Adar-mutant mice develop lethal disease that requires MDA5, the RIG-I-like receptor LGP2, type I interferons, and the eIF2 kinase PKR. We show that a small molecule inhibitor of the integrated stress response (ISR) that acts downstream of eIF2 phosphorylation prevents immunopathology and rescues the mice from mortality. These findings place PKR and the ISR as central components of immunopathology in vivo and identify new therapeutic targets for treatment of human diseases associated with the ADAR1-MDA5 axis.

immunology↗

bioRxiv2020

Neutrophils Mediate Kidney Inflammation Following Acute Skin Exposure to UVB Light

Photosensitivity to ultraviolet (UV) light affects up to ~80% of lupus patients and can exacerbate local skin disease as well as systemic disease, including lupus nephritis. While neutrophils have been implicated in local tissue injury in lupus in response to immune complex deposition, whether and how they play a role in photosensitivity induced systemic disease is unknown. Here, we show that following skin exposure to UV light, neutrophils migrate not only to the skin, but also to the kidney, in an IL-17A-dependent manner. Kidney infiltrating neutrophils produced reactive oxygen species and their presence was associated with upregulation of endothelial adhesion molecules and inflammatory cytokines as well as the induction of kidney injury markers, including transient proteinuria. Neutrophils were responsible for inflammation and renal injury as demonstrated by experiments that inhibited neutrophil mobilization. Exploiting a mouse model containing photoactivatable immune cells, we observed that a subset of neutrophils found in the kidney had transited through UV light-exposed skin suggesting reverse transmigration. These findings demonstrate that neutrophils mediate transient kidney injury following skin exposure to UV light and, coupled with observations identifying similar neutrophil phenotypes in human lupus, could provide a mechanistic link to explain sun-induced systemic lupus flares.

immunology↗

bioRxiv2020

Canagliflozin Extends Lifespan in Genetically Heterogeneous Male But Not Female Mice

Canagliflozin (Cana) is an inhibitor of the sodium glucose transporter 2 (SGLT2), and is thought to act by blocking renal reuptake and intestinal absorption of glucose. Cana is FDA-approved for treatment of diabetes, and affords protection from cardiovascular and kidney diseases. In the context of the mouse Interventions Testing Program, genetically heterogeneous mice were given chow containing 180 ppm Cana at 7 months of age until their death. Cana extended median survival of male mice by 14%, with p < 0.001 by log-rank test. Cana also increased by 9% the age for 90th percentile survival (p < 0.001 by Wang/Allison test), with parallel effects seen at each of three test sites. Cana did not alter the distribution of inferred cause of death, nor of incidental pathology findings at end-of-life necropsies. No benefits were seen in female mice. The lifespan benefit of Cana is likely to reflect blunting of peak glucose levels, because similar longevity effects are seen in mice given acarbose, a diabetes drug that blocks glucose surges through a distinct mechanism, i.e. slowing breakdown of carbohydrate in the intestine. Interventions that control daily peak glucose levels deserve attention as possible preventive medicines to protect from a wide range of late-life neoplastic and degenerative diseases.Competing Interest StatementThe authors have declared no competing interest.View Full Text

pathology↗