Increased Macrophage-Specific Arterial Infiltration Relates to Noncalcified Plaque and Systemic Immune Activation in People With Human Immunodeficiency Virus.

BACKGROUND: Persistent immune activation is thought to contribute to heightened atherosclerotic cardiovascular disease (ASCVD) risk among people with human immunodeficiency virus (PWH). METHODS: Participants (≥18 years) with or without human immunodeficiency virus (HIV) and without history of clinical ASCVD were enrolled. We hypothesized that increased macrophage-specific arterial infiltration would relate to plaque composition and systemic immune activation among PWH. We applied a novel targeted molecular imaging approach (technetium-99m [99mTc]-tilmanocept single photon emission computed tomography [SPECT]/CT) and comprehensive immune phenotyping. RESULTS: Aortic 99mTc-tilmanocept uptake was significantly higher among PWH (n = 20) than participants without HIV (n = 10) with similar 10-year ASCVD risk (P = .02). Among PWH, but not among participants without HIV, noncalcified aortic plaque volume related directly to aortic 99mTc-tilmanocept uptake at different uptake thresholds. An interaction (P = .001) was seen between HIV status and noncalcified plaque volume, but not calcified plaque (P = .83). Systemic levels of caspase-1 (P = .004), CD14-CD16+ (nonclassical/patrolling/homing) monocytes (P = .0004) and CD8+ T cells (P = .005) related positively and CD4+/CD8+ T-cell ratio (P = .02) inversely to aortic 99mTc-tilmanocept uptake volume. CONCLUSIONS: Macrophage-specific arterial infiltration was higher among PWH and related to noncalcified aortic plaque volume only among PWH. Key systemic markers of immune activation relating to macrophage-specific arterial infiltration may contribute to heightened ASCVD risk among PWH. CLINICAL TRIALS REGISTRATION: NCT02542371.

Concurrent Isolation of 3 Distinct Cardiac Stem Cell Populations From a Single Human Heart Biopsy.

RATIONALE: The relative actions and synergism between distinct myocardial-derived stem cell populations remain obscure. Ongoing debates on optimal cell population(s) for treatment of heart failure prompted implementation of a protocol for isolation of multiple stem cell populations from a single myocardial tissue sample to develop new insights for achieving myocardial regeneration. OBJECTIVE: Establish a robust cardiac stem cell isolation and culture protocol to consistently generate 3 distinct stem cell populations from a single human heart biopsy. METHODS AND RESULTS: Isolation of 3 endogenous cardiac stem cell populations was performed from human heart samples routinely discarded during implantation of a left ventricular assist device. Tissue explants were mechanically minced into 1 mm3 pieces to minimize time exposure to collagenase digestion and preserve cell viability. Centrifugation removes large cardiomyocytes and tissue debris producing a single cell suspension that is sorted using magnetic-activated cell sorting technology. Initial sorting is based on tyrosine-protein kinase Kit (c-Kit) expression that enriches for 2 c-Kit+ cell populations yielding a mixture of cardiac progenitor cells and endothelial progenitor cells. Flowthrough c-Kit- mesenchymal stem cells are positively selected by surface expression of markers CD90 and CD105. After 1 week of culture, the c-Kit+ population is further enriched by selection for a CD133+ endothelial progenitor cell population. Persistence of respective cell surface markers in vitro is confirmed both by flow cytometry and immunocytochemistry. CONCLUSIONS: Three distinct cardiac cell populations with individualized phenotypic properties consistent with cardiac progenitor cells, endothelial progenitor cells, and mesenchymal stem cells can be successfully concurrently isolated and expanded from a single tissue sample derived from human heart failure patients.

Projecting the future of an alpine ungulate under climate change scenarios.

Climate change represents a primary threat to species persistence and biodiversity at a global scale. Cold adapted alpine species are especially sensitive to climate change and can offer key "early warning signs" about deleterious effects of predicted change. Among mountain ungulates, survival, a key determinant of demographic performance, may be influenced by future climate in complex, and possibly opposing ways. Demographic data collected from 447 mountain goats in 10 coastal Alaska, USA, populations over a 37-year time span indicated that survival is highest during low snowfall winters and cool summers. However, general circulation models (GCMs) predict future increase in summer temperature and decline in winter snowfall. To disentangle how these opposing climate-driven effects influence mountain goat populations, we developed an age-structured population model to project mountain goat population trajectories for 10 different GCM/emissions scenarios relevant for coastal Alaska. Projected increases in summer temperature had stronger negative effects on population trajectories than the positive demographic effects of reduced winter snowfall. In 5 of the 10 GCM/representative concentration pathway (RCP) scenarios, the net effect of projected climate change was extinction over a 70-year time window (2015-2085); smaller initial populations were more likely to go extinct faster than larger populations. Using a resource selection modeling approach, we determined that distributional shifts to higher elevation (i.e., "thermoneutral") summer range was unlikely to be a viable behavioral adaptation strategy; due to the conical shape of mountains, summer range was expected to decline by 17%-86% for 7 of the 10 GCM/RCP scenarios. Projected declines of mountain goat populations are driven by climate-linked bottom-up mechanisms and may have wide ranging implications for alpine ecosystems. These analyses elucidate how projected climate change can negatively alter population dynamics of a sentinel alpine species and provide insight into how demographic modeling can be used to assess risk to species persistence.

Benefits of migration in relation to nutritional condition and predation risk in a partially migratory moose population.

The costs and benefits of alternative migratory strategies are often framed in the context of top-down and bottom-up effects on individual fitness. This occurs because migration is considered a costly behavioral strategy that presumably confers explicit benefits to migrants in the form of either decreased predation risk (predation risk avoidance hypothesis) or increased nutrition (forage maturation hypothesis). To test these hypotheses, we studied a partially migratory moose (Alces alces) population and contrasted explicit measures of predation risk (i.e., offspring survival) and nutrition (i.e., accumulation of endogenous energy reserves) between resident and migratory subpopulations. We relied on data collected from migratory and nonmigratory radio-marked moose (n = 67) that inhabited a novel study system located in coastal Alaska between 2004 and 2010. In this area, 30% of the population resides year-round on a coastal foreland area, while 48% migrate to either a small island archipelago or a subalpine ridge system (the remainder exhibited one of six different low-occurrence strategies). Overall, we determined that accumulation of body fat during the growing season did not differ between migratory or resident modalities. However, calf survival was 2.6-2.9 times higher for individuals that migrated (survival, islands = 0.49 +/- 0.16 [mean +/- SE], n = 35; ridge = 0.52 +/- 0.16, n = 33) than those that did not (survival, resident = 0.19 +/- 0.08, n = 57). Our results support the predation risk avoidance hypotheses, and suggest that migration is a behavioral strategy that principally operates to reduce the risk of calf predation and does not confer explicit nutritional benefits. We did not directly detect trade-offs between predation risk and nutrition for migratory individuals. Yet we identify an indirect life history mechanism that may mildly dampen the apparent fitness benefits of migration. The proximate factors accounting for differences in migration-specific neonate survival are likely linked to accessibility of refugial habitats for moose at local and landscape scales, landscape factors that affect hunting efficacy of large carnivores, and interactions with rural human communities. Conservation of ungulate populations can be aided by integrating knowledge about migratory behavior, life history strategies, and factors that alter ungulate vulnerability, particularly those induced by human activity.

Galectin-3, Galectin-9, and Interleukin-18 Are Associated with Monocyte/Macrophage Activation and Turnover More so than Simian Immunodeficiency Virus-Associated Cardiac Pathology or Encephalitis.

Despite antiretroviral therapy (ART), people living with HIV (PLWH) are at increased risk of developing cardiovascular disease (CVD) and HIV-associated neurocognitive disorder (HAND), among other comorbidities. Studies from ART-treated individuals identified galectin-3 (gal-3) and interleukin (IL)-18 as CVD biomarkers, galectin-9 (gal-9) as a HAND biomarker, and sCD163, a marker of monocyte/macrophage activation, as a biomarker of both. We asked if plasma gal-3, gal-9, and IL-18 are associated with an individual comorbidity or increase in both with animals that develop AIDS with both pathologies versus (CVD-path) alone or simian immunodeficiency virus encephalitis (SIVE) alone. We found that no biomarkers were selective between individual pathologies, and all biomarkers increased with co-development of CVD-path and SIVE (gal-3, p = 0.11; gal-9, p = 0.001; IL-18, p = 0.007; sCD163, p < 0.001; %BrdU p = 0.02). Although gal-3, gal-9, and IL-18 did not distinguish between pathologies, they correlated strongly with one another, with sCD163, a marker of monocyte/macrophage activation, and the %BrdU monocytes, a marker of monocyte turnover. Compared to animals with CVD-path or SIVE alone, animals that co-developed both pathologies had consistently elevated IL-18 throughout infection (p = 0.02) and increased sCD163 in late infection (p = 0.01). These data indicate that gal-3, gal-9, and IL-18 are associated with monocyte/macrophage activation by sCD163 and monocyte turnover by the %BrdU+ monocytes more so than CVD-path or SIVE.

Snow avalanches are a primary climate-linked driver of mountain ungulate populations.

Snow is a major, climate-sensitive feature of the Earth's surface and catalyst of fundamentally important ecosystem processes. Understanding how snow influences sentinel species in rapidly changing mountain ecosystems is particularly critical. Whereas effects of snow on food availability, energy expenditure, and predation are well documented, we report how avalanches exert major impacts on an ecologically significant mountain ungulate - the coastal Alaskan mountain goat (Oreamnos americanus). Using long-term GPS data and field observations across four populations (421 individuals over 17 years), we show that avalanches caused 23-65% of all mortality, depending on area. Deaths varied seasonally and were directly linked to spatial movement patterns and avalanche terrain use. Population-level avalanche mortality, 61% of which comprised reproductively important prime-aged individuals, averaged 8% annually and exceeded 22% when avalanche conditions were severe. Our findings reveal a widespread but previously undescribed pathway by which snow can elicit major population-level impacts and shape demographic characteristics of slow-growing populations of mountain-adapted animals.

Association of T-cell subtypes with macrophage-specific arterial infiltration in PWH.

People with human immunodeficiency virus (HIV, PWH) face an increased risk of cardiovascular disease (CVD) compared to the general population. We previously demonstrated that people with (versus without) HIV have higher macrophage-specific arterial infiltration in relation to systemic monocyte activation. We now show that select T lymphocyte subpopulations (naïve CD4+, effector memory CD4+, and central memory CD8+) are differentially associated with macrophage-specific arterial infiltration among participants with versus without HIV, with evidence of interaction by HIV status. Our results suggest that among PWH, circulating T lymphocytes associate with macrophage-specific arterial infiltration, of relevance to atherogenesis and CVD risk. CLINICAL TRIALS REGISTRATION: NCT02542371.

Simian immunodeficiency virus-infected rhesus macaques with AIDS co-develop cardiovascular pathology and encephalitis.

Despite effective antiretroviral therapy, HIV co-morbidities remain where central nervous system (CNS) neurocognitive disorders and cardiovascular disease (CVD)-pathology that are linked with myeloid activation are most prevalent. Comorbidities such as neurocogntive dysfunction and cardiovascular disease (CVD) remain prevalent among people living with HIV. We sought to investigate if cardiac pathology (inflammation, fibrosis, cardiomyocyte damage) and CNS pathology (encephalitis) develop together during simian immunodeficiency virus (SIV) infection and if their co-development is linked with monocyte/macrophage activation. We used a cohort of SIV-infected rhesus macaques with rapid AIDS and demonstrated that SIV encephalitis (SIVE) and CVD pathology occur together more frequently than SIVE or CVD pathology alone. Their co-development correlated more strongly with activated myeloid cells, increased numbers of CD14+CD16+ monocytes, plasma CD163 and interleukin-18 (IL-18) than did SIVE or CVD pathology alone, or no pathology. Animals with both SIVE and CVD pathology had greater numbers of cardiac macrophages and increased collagen and monocyte/macrophage accumulation, which were better correlates of CVD-pathology than SIV-RNA. Animals with SIVE alone had higher levels of activated macrophage biomarkers and cardiac macrophage accumulation than SIVnoE animals. These observations were confirmed in HIV infected individuals with HIV encephalitis (HIVE) that had greater numbers of cardiac macrophages and fibrosis than HIV-infected controls without HIVE. These results underscore the notion that CNS and CVD pathologies frequently occur together in HIV and SIV infection, and demonstrate an unmet need for adjunctive therapies targeting macrophages.

Habitat selection predicts genetic relatedness in an alpine ungulate.

Landscape heterogeneity plays an integral role in shaping ecological and evolutionary processes. Despite links between the two disciplines, ecologists and population geneticists have taken different approaches to evaluating habitat selection, animal movement, and gene flow across the landscape. Ecologists commonly use statistical models such as resource selection functions (RSFs) to identify habitat features disproportionately selected by animals, whereas population genetic approaches model genetic differentiation according to the distribution of habitat variables. We combined ecological and genetic approaches by using RSFs to predict genetic relatedness across a heterogeneous landscape. We constructed sex- and season-specific resistance surfaces based on RSFs estimated using data from 102 GPS (global positioning system) radio-collared mountain goats (Oreamnos americanus) in southeast Alaska, USA. Based on mountain goat ecology, we hypothesized that summer and male surfaces would be the best predictors of relatedness. All individuals were genotyped at 22 microsatellite loci, which we used to estimate genetic relatedness. Summer resistance surfaces derived from RSFs were the best predictors of genetic relatedness, and winter models the poorest. Mountain goats generally selected for areas close to escape terrain and with a high heat load (a metric related to vegetative productivity and snow depth), while avoiding valleys. Male- and female-specific surfaces were similar, except for winter, for which male habitat selection better predicted genetic relatedness. The null models of isolation-by-distance and barrier only outperformed the winter models. This study merges high-resolution individual locations through GPS telemetry and genetic data, that can be used to validate and parameterize landscape genetics models, and further elucidates the relationship between landscape heterogeneity and genetic differentiation.

Staying close to home: Ecological constraints on space use and range fidelity in a mountain ungulate.

Understanding patterns of animal space use and range fidelity has important implications for species and habitat conservation. For species that live in highly seasonal environments, such as mountain goats (Oreamnos americanus), spatial use patterns are expected to vary in relation to seasonal changes in environmental conditions and sex- or age-specific selection pressures. To address hypotheses about sex, age, and seasonality influence on space-use ecology, we collected GPS location data from 263 radio-collared mountain goats (males, n = 140; females, n = 123) in coastal Alaska during 2005-2016. Location data were analyzed to derive seasonal and sex-specific fixed-kernel home range estimates and to quantify the degree of seasonal range and utilization distribution overlap. Overall, we determined that home range size was smallest during winter, expanded coincident with the onset of green-up and parturition, and was largest during summer. Home range size of males and females did not differ significantly during winter, but females had larger home ranges than males during summer, a relationship that was switched during the mating season. Pairwise comparisons involving individual females across subsequent years indicated home ranges were significantly smaller during years when they gave birth to offspring. Mountain goats exhibited a strong degree of range fidelity, and 99% (n = 138) of individual animals returned to their previous year's seasonal range with an average annual Bhattacharyya's affinity utilization distribution overlap index of 68%. Similarity of seasonal home range utilization distributions varied in relation to sex and season in some respects. Home range overlap was highest during the summer vegetation growing season, particularly among females. These findings advance our understanding about how environmental variation and sex- and age-related reproductive constraints influence space use and range fidelity among alpine ungulates. Documentation of the high degree of range fidelity among mountain goats has important conservation implications in landscapes increasingly altered by anthropogenic activities.

Steep and deep: Terrain and climate factors explain brown bear (Ursus arctos) alpine den site selection to guide heli-skiing management.

Winter recreation and tourism continue to expand worldwide, and where these activities overlap with valuable wildlife habitat, there is greater potential for conservation concerns. Wildlife populations can be particularly vulnerable to disturbance in alpine habitats as helicopters and snowmachines are increasingly used to access remote backcountry terrain. Brown bears (Ursus arctos) have adapted hibernation strategies to survive this period when resources and energy reserves are limited, and disturbance could negatively impact fitness and survival. To help identify areas of potential conflict between helicopter skiing and denning brown bears in Alaska, we developed a model to predict alpine denning habitat and an associated data-based framework for mitigating disturbance activities. Following den emergence in spring, we conducted three annual aerial surveys (2015-2017) and used locations from three GPS-collared bears (2008-2014) to identify 89 brown bear dens above the forest line. We evaluated brown bear den site selection of land cover, terrain, and climate factors using resource selection function (RSF) models. Our top model supported the hypothesis that bears selected dens based on terrain and climate factors that maximized thermal efficiency. Brown bears selected den sites characterized by steep slopes at moderate elevations in smooth, well-drained topographies that promoted vegetation and deep snow. We used the RSF model to map relative probability of den selection and found 85% of dens occurred within terrain predicted as prime denning habitat. Brown bear exposure to helicopter disturbance was evident as moderate to high intensities of helicopter flight tracking data overlapped prime denning habitat, and we quantified where the risk of these impact was greatest. We also documented evidence of late season den abandonment due to disturbance from helicopter skiing. The results from this study provide valuable insights into bear denning habitat requirements in subalpine and alpine landscapes. Our quantitative framework can be used to support conservation planning for winter recreation industries operating in habitats occupied by denning brown bears.

Enhancing myocardial repair with CardioClusters.

Cellular therapy to treat heart failure is an ongoing focus of intense research, but progress toward structural and functional recovery remains modest. Engineered augmentation of established cellular effectors overcomes impediments to enhance reparative activity. Such 'next generation' implementation includes delivery of combinatorial cell populations exerting synergistic effects. Concurrent isolation and expansion of three distinct cardiac-derived interstitial cell types from human heart tissue, previously reported by our group, prompted design of a 3D structure that maximizes cellular interaction, allows for defined cell ratios, controls size, enables injectability, and minimizes cell loss. Herein, mesenchymal stem cells (MSCs), endothelial progenitor cells (EPCs) and c-Kit+ cardiac interstitial cells (cCICs) when cultured together spontaneously form scaffold-free 3D microenvironments termed CardioClusters. scRNA-Seq profiling reveals CardioCluster expression of stem cell-relevant factors, adhesion/extracellular-matrix molecules, and cytokines, while maintaining a more native transcriptome similar to endogenous cardiac cells. CardioCluster intramyocardial delivery improves cell retention and capillary density with preservation of cardiomyocyte size and long-term cardiac function in a murine infarction model followed 20 weeks. CardioCluster utilization in this preclinical setting establish fundamental insights, laying the framework for optimization in cell-based therapeutics intended to mitigate cardiomyopathic damage.

Space, time and captivity: quantifying the factors influencing the fecal microbiome of an alpine ungulate.

The community of microorganisms in the gut is affected by host species, diet and environment and is linked to normal functioning of the host organism. Although the microbiome fluctuates in response to host demands and environmental changes, there are core groups of microorganisms that remain relatively constant throughout the hosts lifetime. Ruminants are mammals that rely on highly specialized digestive and metabolic modifications, including microbiome adaptations, to persist in extreme environments. Here, we assayed the fecal microbiome of four mountain goat (Oreamnos americanus) populations in western North America. We quantified fecal microbiome diversity and composition among groups in the wild and captivity, across populations and in a single group over time. There were no differences in community evenness or diversity across groups, although we observed a decreasing diversity trend across summer months. Pairwise sample estimates grouped the captive population distinctly from the wild populations, and moderately grouped the southern wild group distinctly from the two northern wild populations. We identified 33 genera modified by captivity, with major differences in key groups associated with cellulose degradation that likely reflect differences in diet. Our findings are consistent with other ruminant studies and provide baseline microbiome data in this enigmatic species, offering valuable insights into the health of wild alpine ungulates.

A Survey of Bacterial Respiratory Pathogens in Native and Introduced Mountain Goats ( Oreamnos americanus).

In contrast to broad range expansion through translocations, many mountain goat ( Oreamnos americanus) populations have shown signs of decline. Recent documentation of pneumonia in mountain goats highlights their susceptibility to bacterial pathogens typically associated with bighorn sheep ( Ovis canadensis) epizootics. Respiratory pathogen communities of mountain goats are poorly characterized yet have important implications for management and conservation of both species. We characterized resident pathogen communities across a range of mountain goat populations as an initial step to inform management efforts. Between 2010 and 2017, we sampled 98 individuals within three regions of the Greater Yellowstone Area (GYA), with a smaller sampling effort in southeast Alaska, US. Within the GYA, we detected Mycoplasma ovipneumoniae in two regions and we found at least two Pasteurellaceae species in animals from all regions. Mannheimia haemolytica was the only pathogen that we detected in southeast Alaska. Given the difficult sampling conditions, limited sample size, and imperfect detection, our failure to detect specific pathogens should be interpreted with caution. Nonetheless, respiratory pathogens within the GYA may be an important, yet underappreciated, cause of mountain goat mortality. Moreover, because of the strong niche overlap of bighorn sheep and mountain goats, interspecific transmission is an important concern for managers restoring or introducing mountain ungulates within sympatric ranges.