Evaluation of IL-17D in Host Immunity to Group A Streptococcus Infection.

IL-17D is a cytokine that belongs to the IL-17 family and is conserved in vertebrates and invertebrates. In contrast to IL-17A and IL-17F, which are expressed in Th17 cells, IL-17D is expressed broadly in nonimmune cells. IL-17D can promote immune responses to cancer and viruses in part by inducing chemokines and recruiting innate immune cells such as NK cells. Although bacterial infection can induce IL-17D in fish and invertebrates, the role of mammalian IL-17D in antibacterial immunity has not been established. To determine whether IL-17D has a role in mediating host defense against bacterial infections, we studied i.p. infection by group A Streptococcus (GAS) in wild-type (WT) and Il17d -/- mice. Compared with WT animals, mice deficient in IL-17D experienced decreased survival, had greater weight loss, and showed increased bacterial burden in the kidney and peritoneal cavity following GAS challenge. In WT animals, IL-17D transcript was induced by GAS infection and correlated to increased levels of chemokine CCL2 and greater neutrophil recruitment. Of note, GAS-mediated IL-17D induction in nonimmune cells required live bacteria, suggesting that processes beyond recognition of pathogen-associated molecular patterns were required for IL-17D induction. Based on our results, we propose a model in which nonimmune cells can discriminate between nonviable and viable GAS cells, responding only to the latter by inducing IL-17D.

Determining Spread Rate of Kudzu Bug (Hemiptera: Plataspidae) and Its Associations With Environmental Factors in a Heterogeneous Landscape.

By the end of 2017, kudzu bug was reported in 652 counties in the United States since it was first observed in Georgia in 2009. Modeling its invasion dynamics is valuable to guide management through early detection and prevention of further invasion. Herein, we initially estimated the spread rate of kudzu bug with county-level invasion records and then determined important spatial factors affecting its spread during years 2010-2016. As kudzu bug infests a large heterogeneous area and shows asymmetric spread, we first utilized spatially constrained clustering (SCC), an unsupervised machine learning method, to divide the infested area into eight spatially contiguous and environmentally homogenous neighborhoods. We then used distance regression and boundary displacement methods to estimate the spread rates in all neighborhoods. Finally, we applied multiple regression to determine spatial factors influencing the spread of kudzu bug. The average spread rate reached 76 km/yr by boundary displacement method; however, the rate varied largely among eight neighborhoods (45-144 km/yr). In the southern region of the infested area, host plant density and wind speed were positively associated with the spread rate, whereas mean annual temperature, precipitation in the fall, and elevation had inverse relationships. In the northern region, January minimum temperature, wind speed, and human population density showed positive relationships. This study increases the knowledge on the spread dynamics of kudzu bug. Our research highlights the utility of SCC to determine natural clustering in a large heterogeneous region for better modeling of local spread patterns and determining important factors affecting the invasions.

Structural and sedimentological connectivity on a rilled hillslope.

Sedimentological connectivity describes the continuity of sediment transport across a topographically heterogenous landscape. Sedimentological connectivity reflects the changes in the balance between flow sediment load and transport capacity and is mainly influenced by the longitudinal (dis)continuity of channels that is associated with channel depressions and confluences. Past studies have focused on structural and sedimentological connectivity at the basin scale, with only a few examining this phenomenon at the hillslope scale. Important questions have yet to be answered, including "How do within-channel barriers and channel confluences affect the flow/sediment balance?" and "At what spatial extent do these influences take place?" This study investigated the structural and sedimentological connectivity within a rill network on a hillslope in Loudon, Tennessee, USA. We used the difference in a ground lidar generated time-series of seven digital elevation models (DEMs), the DEM of Difference (DoD or ΔDEM), to quantify the spatio-temporal dynamics of erosion and deposition on a hillslope for 6 periods from December 2014 to December 2016. We found that later periods had the greatest amount of erosion and net sediment loss (0.59 ±â€¯17 m3). We compared the observed sediment redistribution patterns to a GIS-based index of connectivity (IC). In order to examine the influence of structural (dis) connectivity on sedimentological connectivity, we compared the time series of patterns to the occurrences of rill channel confluences and depressions. We found a spatially consistent relationship between the IC and the observed erosion/deposition pattern. However, sediment detachment can also be driven by gravitational sidewall failure, which is not well described by the IC. The scouring at rill confluences leads to higher erosion in both upslope and downslope sections of a rill channel; the ponding at rill depressions yields upslope deposition and downslope erosion.

The ancient cytokine IL-17D is regulated by Nrf2 and mediates tumor and virus surveillance.

Early stage immune responses can dictate the severity and outcome of inflammatory processes such as tumor growth and viral infection. Cytokines such as the interleukin 17 (IL-17) family and cellular stress defense (e.g., anti-oxidant) pathways have evolved early and regulate disease surveillance in vertebrates and invertebrates as far back as Caenorhabditis elegans. Our group has recently found a new role for nuclear factor erythroid-derived 2-like 2 (Nrf2) in regulating early anti-cancer immune responses by inducing IL-17D and recruiting natural killer (NK) cells. In this Cytokine Stimulus, we discuss recent findings that encourage boosting the Nrf2/IL-17D/NK cell axis for the treatment of cancer and viral infection.

Nrf2 Induces IL-17D to Mediate Tumor and Virus Surveillance.

Cells undergoing xenobiotic or oxidative stress activate the transcription factor nuclear factor erythroid-derived 2-like 2 (Nrf2), which initiates an intrinsic "stress surveillance" pathway. We recently found that the cytokine IL-17D effects a form of extrinsic stress surveillance by inducing antitumor immunity, but how IL-17D is regulated remains unknown. Here, we show that Nrf2 induced IL-17D in cancer cell lines. Moreover, both Nrf2 and IL-17D were induced in primary tumors as well as during viral infection in vivo. Expression of IL-17D in tumors and virally infected cells is essential for optimal protection of the host as il17d(-/-) mice experienced a higher incidence of tumors and exacerbated viral infections compared to wild-type (WT) animals. Moreover, activating Nrf2 to induce IL-17D in established tumors led to natural killer cell-dependent tumor regression. These data demonstrate that Nrf2 can initiate both intrinsic and extrinsic stress surveillance pathways and highlight the use of Nrf2 agonists as immune therapies for cancer and infection.

Decreased Anti-Tumor Cytotoxic Immunity among Microsatellite-Stable Colon Cancers from African Americans.

Colorectal cancer is a leading cause of cancer related deaths in the U.S., with African-Americans having higher incidence and mortality rates than Caucasian-Americans. Recent studies have demonstrated that anti-tumor cytotoxic T lymphocytes provide protection to patients with colon cancer while patients deficient in these responses have significantly worse prognosis. To determine if differences in cytotoxic immunity might play a role in racial disparities in colorectal cancer 258 microsatellite-stable colon tumors were examined for infiltrating immune biomarkers via immunohistochemistry. Descriptive summary statistics were calculated using two-sample Wilcoxon rank sum tests, while linear regression models with log-transformed data were used to assess differences in race and Pearson and Spearman correlations were used to correlate different biomarkers. The association between different biomarkers was also assessed using linear regression after adjusting for covariates. No significant differences were observed in CD8+ (p = 0.83), CD57+ (p = 0.55), and IL-17-expressing (p = 0.63) cell numbers within the tumor samples tested. When infiltration of granzyme B+ cells was analyzed, however, a significant difference was observed, with African Americans having lower infiltration of cells expressing this cytotoxic marker than Caucasians (p<0.01). Analysis of infiltrating granzyme B+ cells at the invasive borders of the tumor revealed an even greater difference by race (p<0.001). Taken together, the data presented suggest differences in anti-tumor immune cytotoxicity may be a contributing factor in the racial disparities observed in colorectal cancer.

Tree mortality from an exceptional drought spanning mesic to semiarid ecoregions.

Significant areas of the southern USA periodically experience intense drought that can lead to episodic tree mortality events. Because drought tolerance varies among species and size of trees, such events can alter the structure and function of terrestrial ecosystem in ways that are difficult to detect with local data sets or solely with remote-sensing platforms. We investigated a widespread tree mortality event that resulted from the worst 1-year drought on record for the state of Texas, USA. The drought affected ecoregions spanning mesic to semiarid climate zones and provided a unique opportunity to test hypotheses related to how trees of varying genus and size were affected. The study was based on an extensive set of 599 distributed plots, each 0.16 ha, surveyed in the summer following the drought. In each plot, dead trees larger than 12.7 cm in diameter were counted, sized, and identified to the genus level. Estimates of total mortality were obtained for each of 10 regions using a combination of design-based estimators and calibrated remote sensing using MODIS 1-yr change in normalized difference vegetation index products developed by the U.S. Forest Service. As compared with most of the publicized extreme die-off events, this study documents relatively low rates of mortality occurring over a very large area. However, statewide, regional tree mortality was massive, with an estimated 6.2% of the live trees perishing, nearly nine times greater than normal annual mortality. Dead tree diameters averaged larger than the live trees for most ecoregions, and this trend was most pronounced in the wetter climate zones, suggesting a potential re-ordering of species dominance and downward trend in tree size that was specific to climatic regions. The net effect on carbon storage was estimated to be a redistribution of 24-30 Tg C from the live tree to dead tree carbon pool. The dead tree survey documented drought mortality in more than 29 genera across all regions, and surprisingly, drought resistant and sensitive species fared similarly in some regions. Both angiosperms and gymnosperms were affected. These results highlight that drought-driven mortality alters forest structure differently across climatic regions and genera.

Tumor-expressed IL-17D recruits NK cells to reject tumors.

Antitumor immunity suppresses tumorigenesis, but we do not understand how transformed cells initiate those immune responses that are essential for effective tumor immunosurveillance. Using the 3-MCA fibrosarcoma model, we identified IL-17D as a tumor-expressed cytokine that recruits natural killer cells, leading to the polarization of M1 macrophages and tumor rejection.

Monitoring vegetation dynamics and carbon stock density in miombo woodlands.

BACKGROUND: The United Nation's Program for Reducing Emissions from Deforestation and Forest Degradation (REDD+) aims to reduce the 20% contribution to global emissions of greenhouse gases from the forest sector, offering a financial value of the carbon stored in forests as an incentive for local communities. The pre-requisite for the setup of a participatory REDD + Program is the monitoring, reporting and verification (MRV) of baseline carbon stocks and their changes over time. In this study, we investigated miombo woodland's dynamics in terms of composition, structure and biomass over a 4-year period (2005-2009), and the Carbon Stock Density (CSD) for the year 2009. The study was conducted in the Niassa National Reserve (NNR) in northern Mozambique, which is the 14th largest protected area in the world. RESULTS: Mean tree density distributed across 79 species increased slightly between 2005 and 2009, respectively, from 548 to 587 trees ha-1. Julbernardia globiflora (Benth.) was the most important species in this area [importance value index (IVI2005= 61 and IVI2009 = 54)]. The woodlands presented an inverted J-shaped diametric curve, with 69% of the individuals representing the young cohort. Woody biomass had a net increase of 3 Mg ha-1 with the highest growth observed in Dyplorhynchus condilocarpon (Müll.Arg.) Pichon (0.54 Mg ha-1). J. globiflora had a net decrease in biomass of 0.09 Mg ha-1. Total CSD density was estimated at ca. 67 MgC ha-1 ± 24.85 with soils (average 34.72 ± 17.93 MgC ha-1) and woody vegetation (average 29.8 MgC ha-1 ± 13.07) representing the major carbon pools. The results point to a relatively stable ecosystem, but they call for the need to refocus management activities. CONCLUSIONS: The miombo woodlands in NNR are representative of the woodlands in the eco-region in terms of vegetation structure and composition. They experienced net increase in woody biomass, a considerable recruitment level and low mortality. According to our results, NNR may present good potential for carbon sequestration especially in soils and woody biomass, representing an important potential carbon sink. However, further investigations are needed in order to address the contribution of this area to MRV REDD + initiatives.

Retrospective assessment of dryland soil stability in relation to grazing and climate change.

Accelerated soil erosion is an aspect of dryland degradation that is affected by repeated intense drought events and land management activities such as commercial livestock grazing. A soil stability index (SSI) that detects the erosion status and susceptibility of a landscape at the pixel level, i.e., stable, erosional, or depositional pixels, was derived from the spectral properties of an archived time series (from 1972 to 1997) of Landsat satellite data of a commercial ranch in northeastern Utah. The SSI was retrospectively validated with contemporary field measures of soil organic matter and erosion status that was surveyed by US federal land management agencies. Catastrophe theory provided the conceptual framework for retrospective assessment of the impact of commercial grazing and soil water availability on the SSI. The overall SSI trend was from an eroding landscape in the early drier 1970s towards stable conditions in the wetter mid-1980s and late 1990s. The landscape catastrophically shifted towards an extreme eroding state that was coincident with the "The Great North American Drought of 1988". Periods of landscape stability and trajectories toward stability were coincident with extremely wet El Niño events. Commercial grazing had less correlation with soil stability than drought conditions. However, the landscape became more susceptible to erosion events under multiple droughts and grazing. Land managers now have nearly a year warning of El Niño and La Niña events and can adjust their management decisions according to predicted landscape erosion conditions.

Assessing Land-Use Impacts on Natural Resources

/ Much information is available on changes that occur in natural resources from both spatially-explicit data on environmental conditions and models of the interactions of these conditions and resources with human activities. The strategy for assessing land-use impacts on natural resources developed in this paper provides a framework for using relevant data and models to address questions of how management practices can promote both use and protection of resources. This assessment strategy integrates spatially explicit environmental data using geographic information systems (GIS) with computer models that simulate changes in land cover in response to land-use impacts. The computer models also simulate susceptibility of species to changes in habitat suitability and landscape patterns. The approach is applied to management of limestone barrens on the Oak Ridge Reservation in East Tennessee. Potential limestone barrens habitats are identified by overlaying appropriate soils, geology, slope, and land-use/land-cover conditions. Their validity is tested against known sites containing rare species that occur in these habitats. The location of habitats at risk in the aftermath of human activities is determined by using an available area model that identifies the size and proximity of sites that particular types of species can no longer use as habitat. The resulting risk map can be used in land management planning. The approach uses readily available in situ and remotely sensed data and is applicable to a wide range of locations and land-use scenarios. This approach can be refined based on needs identified by land managers and on the sensitivity of the results to the resolution of available resource information.KEY WORDS: Land management; Assessment; Habitat characterization; Limestone barrens; Ecological modeling; Geographic information systems