The Genetic Architecture of Methotrexate Toxicity Is Similar in Drosophila melanogaster and Humans

The severity of the toxic side effects of chemotherapy varies among patients, and much of this variation is likely genetically based. Here, we use the model system Drosophila melanogaster to genetically dissect the toxicity of methotrexate (MTX), a drug used primarily to treat childhood acute lymphoblastic leukemia and rheumatoid arthritis. We use the Drosophila Synthetic Population Resource, a panel of recombinant inbred lines derived from a multiparent advanced intercross, and quantify MTX toxicity as a reduction in female fecundity. We identify three quantitative trait loci (QTL) affecting MTX toxicity; two colocalize with the fly orthologs of human genes believed to mediate MTX toxicity and one is a novel MTX toxicity gene with a human ortholog. A fourth suggestive QTL spans a centromere. Local single-marker association scans of candidate gene exons fail to implicate amino acid variants as the causative single-nucleotide polymorphisms, and we therefore hypothesize the causative variation is regulatory. In addition, the effects at our mapped QTL do not conform to a simple biallelic pattern, suggesting multiple causative factors underlie the QTL mapping results. Consistent with this observation, no single single-nucleotide polymorphism located in or near a candidate gene can explain the QTL mapping signal. Overall, our results validate D. melanogaster as a model for uncovering the genetic basis of chemotoxicity and suggest the genetic basis of MTX toxicity is due to a handful of genes each harboring multiple segregating regulatory factors

Gender Equity in Transplantation: A Report From the Women in Transplantation Workshop of The Transplantation Society of Australia and New Zealand

The exponential growth of young talented women choosing science and medicine as their professional career over the past decade is substantial. Currently, more than half of the Australian medical doctoral graduates and early career researchers are comprised of women, but less than 20% of all academic professorial staff are women. The loss of female talent in the hierarchical ladder of Australian academia is a considerable waste of government investment, productivity, and scientific innovation. Gender disparity in the professional workforce composition is even more striking within the field of transplantation. Women are grossly underrepresented in leadership roles, with currently no female heads of unit in any of the Australian and New Zealand transplanting centers. At the same time, there is also gender segregation with a greater concentration of women in lower-status academic position compared with their male counterparts. Given the extent and magnitude of the disparity, the Women in Transplantation Committee, a subcommittee of The Transplantation Society of Australia and New Zealand established a workshop comprising 8 female clinicians/scientists in transplantation. The key objectives were to (i) identify potential gender equity issues within the transplantation workforce; (ii) devise and implement potential strategies and interventions to address some of these challenges at a societal level; (iii) set realistic and achievable goals to enhance and facility gender equality, equity, and diversity in transplantation

Team-Based Integrated Knowledge Translation for Enhancing Quality of Life in Long-term Care Settings: A Multi-method, Multi-sectoral Research Design

Multi-sectoral, interdisciplinary health research is increasingly recognizing integrated knowledge translation (iKT) as essential. It is characterized by diverse research partnerships, and iterative knowledge engagement, translation processes and democratized knowledge production. This paper reviews the methodological complexity and decision-making of a large iKT project called Seniors - Adding Life to Years (SALTY), designed to generate evidence to improve late life in long-term care (LTC) settings across Canada. We discuss our approach to iKT by reviewing iterative processes of team development and knowledge engagement within the LTC sector. We conclude with a brief discussion of the important opportunities, challenges, and implications these processes have for LTC research, and the sector more broadly

Bone marrow-derived and resident liver macrophages display unique transcriptomic signatures but similar biological functions

Abstract: Background and aims: Kupffer cells (KCs), the resident tissue macrophages of the liver, play a crucial role in the clearance of pathogens and other particulate materials that reach the systemic circulation. Recent studies have identified KCs as a yolk sac-derived resident macrophage population that is replenished independently of monocytes in the steady state. Although it is now established that following local tissue injury, bone-marrow derived monocytes may infiltrate the tissue and differentiate into macrophages, the extent to which newly differentiated macrophages functionally resemble the KCs they have replaced has not been extensively studied. Methods and results: Here we show using intravital microscopy, morphometric analysis and gene expression profiling that bone marrow derived “KCs” accumulating as a result of genotoxic injury resemble, but are not identical to their yolk-sac (YS) counterparts. An ion homeostasis gene signature, including genes associated with scavenger receptor function and extracellular matrix deposition, allows discrimination between these two KC populations. Reflecting the differential expression of scavenger receptors, YS-derived KCs were more effective at accumulating Ac-LDL, whereas surprisingly they were poorer than BM-derived KCs when assessed for uptake of a range of bacterial pathogens. The two KC populations were almost indistinguishable in regard to i) response to LPS challenge, ii) phagocytosis of effete RBCs and iii) their ability to contain infection and direct granuloma formation against Leishmania donovani, a KC-tropic intracellular parasite. Conclusions: BM-derived KCs differentiate locally to resemble YS-derived KC in most but not all respects, with implications for models of infectious diseases, liver injury and bone marrow transplantation. In addition, the gene signature we describe adds to the tools available for distinguishing KC subpopulations based on their ontology

Targeting PI3Kδ function for amelioration of murine chronic graft-versus-host disease.

Chronic graft-versus-host disease (cGVHD) is a leading cause of morbidity and mortality following allotransplant. Activated donor effector T cells can differentiate into pathogenic T helper (Th)-17 cells and germinal center (GC)-promoting T follicular helper (Tfh) cells, resulting in cGVHD. Phosphoinositide-3-kinase-δ (PI3Kδ), a lipid kinase, is critical for activated T cell survival, proliferation, differentiation, and metabolism. We demonstrate PI3Kδ activity in donor T cells that become Tfh cells is required for cGVHD in a nonsclerodermatous multiorgan system disease model that includes bronchiolitis obliterans (BO), dependent upon GC B cells, Tfhs, and counterbalanced by T follicular regulatory cells, each requiring PI3Kδ signaling for function and survival. Although B cells rely on PI3Kδ pathway signaling and GC formation is disrupted resulting in a substantial decrease in Ig production, PI3Kδ kinase-dead mutant donor bone marrow-derived GC B cells still supported BO cGVHD generation. A PI3Kδ-specific inhibitor, compound GS-649443, that has superior potency to idelalisib while maintaining selectivity, reduced cGVHD in mice with active disease. In a Th1-dependent and Th17-associated scleroderma model, GS-649443 effectively treated mice with active cGVHD. These data provide a foundation for clinical trials of US Food and Drug Administration (FDA)-approved PI3Kδ inhibitors for cGVHD therapy in patients

VCAM-1 and VLA-4 Modulate Dendritic Cell IL-12p40 Production in Experimental Visceral Leishmaniasis

Vascular cell adhesion molecule-1 (VCAM-1) interacts with its major ligand very late antigen-4 (VLA-4) to mediate cell adhesion and transendothelial migration of leukocytes. We report an important role for VCAM-1/VLA-4 interactions in the generation of immune responses during experimental visceral leishmaniasis caused by Leishmania donovani. Our studies demonstrate that these molecules play no direct role in the recruitment of leukocytes to the infected liver, but instead contribute to IL-12p40-production by splenic CD8+ dendritic cells (DC). Blockade of VCAM-1/VLA-4 interactions using whole antibody or anti-VCAM-1 Fab′ fragments reduced IL-12p40 mRNA accumulation by splenic DC 5 hours after L. donovani infection. This was associated with reduced anti-parasitic CD4+ T cell activation in the spleen and lowered hepatic IFNγ, TNF and nitric oxide production by 14 days post infection. Importantly, these effects were associated with enhanced parasite growth in the liver in studies with either anti-VCAM-1 or anti-VLA-4 antibodies. These data indicate a role for VCAM-1 and VLA-4 in DC activation during infectious disease

CSF-1–dependant donor-derived macrophages mediate chronic graft-versus-host disease

Chronic GVHD (cGVHD) is the major cause of late, nonrelapse death following stem cell transplantation and characteristically develops in organs such as skin and lung. Here, we used multiple murine models of cGVHD to investigate the contribution of macrophage populations in the development of cGVHD. Using an established IL-17–dependent sclerodermatous cGVHD model, we confirmed that macrophages infiltrating the skin are derived from donor bone marrow (F4/80+CSF-1R+CD206+iNOS–). Cutaneous cGVHD developed in a CSF-1/CSF-1R–dependent manner, as treatment of recipients after transplantation with CSF-1 exacerbated macrophage infiltration and cutaneous pathology. Additionally, recipients of grafts from Csf1r–/– mice had substantially less macrophage infiltration and cutaneous pathology as compared with those receiving wild-type grafts. Neither CCL2/CCR2 nor GM-CSF/GM-CSFR signaling pathways were required for macrophage infiltration or development of cGVHD. In a different cGVHD model, in which bronchiolitis obliterans is a prominent manifestation, F4/80+ macrophage infiltration was similarly noted in the lungs of recipients after transplantation, and lung cGVHD was also IL-17 and CSF-1/CSF-1R dependent. Importantly, depletion of macrophages using an anti–CSF-1R mAb markedly reduced cutaneous and pulmonary cGVHD. Taken together, these data indicate that donor macrophages mediate the development of cGVHD and suggest that targeting CSF-1 signaling after transplantation may prevent and treat cGVHD