6 research outputs found
Heparan Sulfate-Bound Dimeric IL-2: A Potential Mediator of Renal Ischemic Injury
Interleukin-2 (IL-2) is a cytokine critical to normal immune function. Our laboratory has shown that IL-2 is retained in tissues by heparan sulfate (HS). While known as a monomer, a dimeric form of IL-2 was previously identified in fish optic neurons, and this form was toxic to oligodendrocytes. Given this observation, we asked whether dimeric IL-2 is found in mammalian tissues. Murine and human aorta and kidney were assessed by Western blot for the presence of IL-2. Dimeric (30 kD) IL-2 was identified in each tissue. Heparinase digestion of tissues liberated dimeric IL-2, suggesting that the dimer is bound, at least in part, by HS. To ascertain whether dimeric IL-2 is cytotoxic, we treated cultures of renal epithelial cells with increasing concentrations of dimeric IL-2, isolated by electroelution. Signs of cytotoxicity were evident within 15 minutes of dimer addition. Commercial IL-2, isolated identically to dimeric IL-2, was not cytotoxic. Systemic administration to mice of 10 μg of dimeric IL-2 induced vacuolization of renal epithelium, a morphology typically seen with ischemic injury. Finally, murine kidneys subjected to 60 minutes of ischemia, compared to sham controls, expressed greatly increased amounts of dimeric IL-2 in tissue homogenates. These results suggest that dimeric IL-2 may contribute to acute tubular necrosis and, in turn, renal dysfunction. This work was supported by institutional funds
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The Fire and Tree Mortality Database, for empirical modeling of individual tree mortality after fire.
Wildland fires have a multitude of ecological effects in forests, woodlands, and savannas across the globe. A major focus of past research has been on tree mortality from fire, as trees provide a vast range of biological services. We assembled a database of individual-tree records from prescribed fires and wildfires in the United States. The Fire and Tree Mortality (FTM) database includes records from 164,293 individual trees with records of fire injury (crown scorch, bole char, etc.), tree diameter, and either mortality or top-kill up to ten years post-fire. Data span 142 species and 62 genera, from 409 fires occurring from 1981-2016. Additional variables such as insect attack are included when available. The FTM database can be used to evaluate individual fire-caused mortality models for pre-fire planning and post-fire decision support, to develop improved models, and to explore general patterns of individual fire-induced tree death. The database can also be used to identify knowledge gaps that could be addressed in future research