Hematopoietic stem cells exhibit a specific ABC transporter gene expression profile clearly distinct from other stem cells

Contains fulltext : 88395.pdf (publisher's version ) (Open Access)BACKGROUND: ATP-binding cassette (ABC) transporters protect cells against unrelated (toxic) substances by pumping them across cell membranes. Earlier we showed that many ABC transporters are highly expressed in hematopoietic stem cells (HSCs) compared to more committed progenitor cells. The ABC transporter expression signature may guarantee lifelong protection of HSCs but may also preserve stem cell integrity by extrusion of agents that trigger their differentiation. Here we have studied whether non-hematopoietic stem cells (non-HSCs) exhibit a similar ABC transporter expression signature as HSCs. RESULTS: ABC transporter expression profiles were determined in non-hematopoietic stem cells (non-HSCs) from embryonic, neonatal and adult origin as well as in various mature blood cell types. Over 11,000 individual ABC transporter expression values were generated by Taqman Low Density Arrays (TLDA) to obtain a sensitivity comparable with quantitative real-time polymerase chain reactions. We found that the vast majority of transporters are significantly higher expressed in HSCs compared to non-HSCs. Furthermore, regardless their origin, non-HSCs exhibited strikingly similar ABC transporter expression profiles that were distinct from those in HSCs. Yet, sets of transporters characteristic for different stem cell types could be identified, suggesting restricted functions in stem cell physiology. Remarkably, in HSCs we could not pinpoint any single transporter expressed at an evidently elevated level when compared to all the mature blood cell types studied. CONCLUSIONS: These findings challenge the concept that individual ABC transporters are implicated in maintaining stem cell integrity. Instead, a distinct ABC transporter expression signature may be essential for stem cell function. The high expression of specific transporters in non-HSCs and mature blood cells suggests a specialized, cell type dependent function and warrants further functional experiments to determine their exact roles in cellular (patho)physiology

Mutational spectrum and dynamics of clonal hematopoiesis in anemia of older individuals

Anemia is a major and currently poorly understood clinical manifestation of hematopoietic aging. Upon aging, hematopoietic clones harboring acquired leukemia-associated mutations expand and become detectable, now referred to as clonal hematopoiesis (CH). To investigate the relationship between CH and anemia of the elderly, we explored the landscape and dynamics of CH in older individuals with anemia. From the prospective, population-based Lifelines cohort (n = 167 729), we selected all individuals at least 60 years old who have anemia according to World Health Organization criteria (n = 676) and 1:1 matched control participants. Peripheral blood of 1298 individuals was analyzed for acquired mutations at a variant allele frequency (VAF) of 1% or higher in 27 driver genes. To track clonal evolution over time, we included all available follow-up samples (n = 943). CH was more frequently detected in individuals with anemia (46.6%) compared with control individuals (39.1%; P = .007). Although no differences were observed regarding commonly detected DTA mutations (DNMT3A, TET2, ASXL1) in individuals with anemia compared with control individuals, other mutations were enriched in the anemia cohort, including TP53 and SF3B1. Unlike individuals with nutrient deficiency (P = .84), individuals with anemia of chronic inflammation and unexplained anemia revealed a higher prevalence of CH (P = .035 and P = .017, respectively) compared with their matched control individuals. Follow-up analyses revealed that clones may expand and decline, generally showing only a subtle increase in VAF (mean, 0.56%) over the course of 44 months, irrespective of the presence of anemia. Specific mutations were associated with different growth rates and propensities to acquire an additional hit. In contrast to smaller clones (<5% VAF), which did not affect overall survival, larger clones were associated with increased risk for death

Peripheral blood cytopenias in the aging general population and risk of incident hematological disease and mortality

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Prevalence, predictors, and outcomes of clonal hematopoiesis in individuals aged ≥80 years

Clonal hematopoiesis (CH), characterized by a fraction of peripheral blood cells carrying an acquired genetic variant, emerges with age. Although in general CH is associated with increased mortality and morbidity, no higher risk of death was observed for individuals ≥80 years. Here, we investigated CH in 621 individuals aged ≥80 years from the population-based LifeLines cohort. Sensitive error-corrected sequencing of 27 driver genes at a variant allele frequency ≥1% revealed CH in the majority (62%) of individuals, independent of gender. The observed mutational spectrum was dominated by DNMT3A and TET2 variants, which frequently (29%) displayed multiple mutations per gene. In line with previous results in individuals ≥80 years, the overall presence of CH did not associate with a higher risk of death (hazard ratio, 0.91; 95% confidence interval, 0.70-1.18; P = .48). Being able to assess the causes of death, we observed no difference between individuals with or without CH, except for deaths related to hematological malignancies. Interestingly, comparison of mutational spectra confined to DNMT3A and TET2 vs spectra containing other mutated genes, showed a higher risk of death when mutations other than DNMT3A or TET2 were present (hazard ratio, 1.48; 95% confidence interval, 1.06-2.08; P = .025). Surprisingly, no association of CH with cardiovascular morbidity was found, irrespective of clone size. Further, CH associated with chronic obstructive pulmonary disease. Data on estimated exposure to DNA damaging toxicities (ie, smoking, a history of cancer [as a proxy for previous genotoxic therapy], and job-related pesticide exposure) showed an association with spliceosome and ASXL1 variants, but not with DNMT3A and TET2 variants

The effect of induction therapy with infliximab or vedolizumab on hepcidin and iron status in patients with Inflammatory Bowel Disease

Background Differentiating absolute iron deficiency from functional iron restriction is challenging in active Inflammatory Bowel Disease (IBD). Hepcidin, the systemic iron regulator, could be the key in the diagnosis and management of absolute iron deficiency. In this study, we assessed hepcidin as a diagnostic iron deficiency marker and we explored the relationship between hepcidin, inflammation, hypoxia, and iron deficiency in patients receiving induction therapy with infliximab (IFX) or vedolizumab (VEDO). Methods 130 patients with IBD, who received induction therapy with IFX or VEDO for active disease, were included in this study. Clinical and biochemical data were extracted from medical records. Serum samples at baseline and week 6 of induction therapy were retrieved from the University Medical Center Groningen (UMCG) biobank and analysed for: hepcidin, inflammation (e.g., interleukins [IL] 6, 10, and Tumour Necrosis Factor-α [TNFα]), oxidative stress (free thiols), and hypoxia (e.g., erythropoietin [EPO], Macrophage Inflammatory Protein-3α [MIP3α]). For comparison, serum samples from 50 age- and gender-matched healthy controls were obtained from pre-donation biobank at the UMCG. Response to therapy was defined by either General Physician’s Assessment at week 14 of induction therapy, normalisation or at least a three-point decrease in clinical scores: Harvey-Bradshaw Index (HBI) for Crohn’s Disease, Simple Clinical Colitis Activity Index (SCCAI) for ulcerative colitis. Results Hepcidin correlated with ferritin and sTfR/log ferritin index [ρ = 0.74 and ρ = -0.79, respectively; P<0.001 for both markers], while inflammation- and hypoxia-associated markers showed only marginal correlations. Hepcidin accurately identified absolute iron deficiency: AUC(hepcidin) = 0.89 [95% CI: 0.82–0.95; P<0.001]. Induction with either IFX or VEDO decreased hepcidin [13.5 ng/mL vs. 9.5 ng/mL; P<0.001], ferritin [45.5 ug/L vs. 37.0 ug/L, P<0.05], and inflammatory markers at week 6, while transferrin increased [2.4 g/L vs. 2.5 g/L, P<0.001]. In total, 75.4% of patients responded to the induction therapy. Hepcidin and ferritin decreased, while transferrin increased (P<0.001 for all changes) in patients who responded to the therapy. In addition, hypoxia (EPO and MIP3α) and inflammatory markers such as faecal calprotectin, IL-6, IL-22, and TNFα improved significantly. In contrast, none of these improvements were observed in patients who did not respond to the therapy. Conclusion Hepcidin reflects iron deficiency in active IBD, but inflammation masks the severity of the deficiency. Induction therapy with either IFX or VEDO modulates hepcidin and iron indices, especially in patients who respond to the therapy

How habitat-modifying organisms structure the food web of two coastal ecosystems

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Motives for choosing growth-enhancing hormone treatment in adolescents with idiopathic short stature: a questionnaire and structured interview study

Background Growth-enhancing hormone treatment is considered a possible intervention in short but otherwise healthy adolescents. Although height gain is an obvious measure for evaluating hormone treatment, this may not be the ultimate goal for the person, but rather a means to reach other goals such as the amelioration of current height-related psychosocial problems or the enhancement of future prospects in life and society. The aim of our study was to clarify the motives of adolescents and their parents when choosing to participate in a growth-enhancing trial combining growth hormone and puberty-delaying hormone treatment. Methods Participants were early pubertal adolescents (25 girls, 13 boys) aged from 11 to 13 years (mean age 11.5 years) with a height standard deviation score (SDS) ranging from -1.03 to -3.43. All had been classified as idiopathic short stature or persistent short stature born small for the gestational age (intrauterine growth retardation) on the basis of a height SDS below -2, or had a height SDS between -1 and -2 and a predicted adult height SDS below -2. The adolescents and their parents completed questionnaires and a structured interview on the presence of height-related stressors, parental worries about their child's behavior and future prospects, problems in psychosocial functioning, and treatment expectations. Questionnaire scores were compared to norms of the general Dutch population. Results The adolescents reported normal psychosocial functioning and highly positive expectations of the treatment in terms of height gain, whereas the parents reported that their children encountered some behavioral problems (being anxious/depressed, and social and attention problems) and height-related stressors (being teased and juvenilized). About 40% of the parents were worried about their children's future prospects for finding a spouse or job. The motives of the adolescents and their parents exhibited rather different profiles. The most prevalent parental worries related to the current or future functioning of their children, while a few cases were characterized by no observed motives or by psychosocial problems only reported by the adolescents themselves. Conclusion The motives for participating in a growth-enhancing hormone trial are more obvious in the parents than in the adolescents themselves. Two out of three parents report worries about the future opportunities or observe modest current psychosocial problems in their children. The adolescents want to gain height, but the motivation underlying this remains unclear. Few of the adolescents experience psychosocial problems. Our analyses revealed differences among individuals in terms of motives, which implies that in an evaluation of hormone treatment, the importance of divergent outcome variables will also differ among individuals. Effectiveness evaluations of hormone treatment to increase height and the consequential fulfillment of other goals must be awaited

Drought, mutualism breakdown, and landscape-scale degradation of seagrass beds

In many marine ecosystems, biodiversity critically depends on foundation species such as corals and seagrasses that engage in mutualistic interactions [1-3]. Concerns grow that environmental disruption of marine mutualisms exacerbates ecosystem degradation, with breakdown of the obligate coral mutualism ("coral bleaching") being an iconic example [2, 4, 5]. However, as these mutualisms are mostly facultative rather than obligate, it remains unclear whether mutualism breakdown is a common risk in marine ecosystems, and thus a potential accelerator of ecosystem degradation. Here, we provide evidence that drought triggered landscape-scale seagrass degradation and show the consequent failure of a facultative mutualistic feedback between seagrass and sulfide-consuming lucinid bivalves that in turn appeared to exacerbate the observed collapse. Local climate and remote sensing analyses revealed seagrass collapse after a summer with intense low-tide drought stress. Potential analysis-a novel approach to detect feedback-mediated state shifts-revealed two attractors (healthy and degraded states) during the collapse, suggesting that the drought disrupted internal feedbacks to cause abrupt, patch-wise degradation. Field measurements comparing degraded patches that were healthy before the collapse with patches that remained healthy demonstrated that bivalves declined dramatically in degrading patches with associated high sediment sulfide concentrations, confirming the breakdown of the mutualistic seagrass-lucinid feedback. Our findings indicate that drought triggered mutualism breakdown, resulting in toxic sulfide concentrations that aggravated seagrass degradation. We conclude that external disturbances can cause sudden breakdown of facultative marine mutualistic feedbacks. As this may amplify ecosystem degradation, we suggest including mutualisms in marine conservation and restoration approaches

Buckling of Carbon Honeycombs: A New Mechanism for Molecular Mass Transportation

<p>Differentially expressed genes in the CD34+ cell fraction in MDS patients versus controls.</p