Biology subjects

Cirovic, B.

Publications and source records attributed to Cirovic, B..

4 recordsLinked to original sources

bioRxiv2026

Early postnatal Flt3+ hematopoietic progenitors realize fate-restricted and long-lived output in vivo

Hematopoietic progenitors downstream of hematopoietic stem cells (HSC) are now recognized as the main drivers of day-to-day hematopoiesis. While embryonic and adult HSC fates have been studied in detail, less information exists on stages downstream from HSC, notably in the multipotent progenitor compartment. The early postnatal period represents an important growth phase of the animal and its immune system. Developing immune lineages must be generated in large numbers rapidly, and populate expanding organ niches. To shed light on this critical period, we focused our experiments on early postnatal Flt3+ hematopoietic progenitors, and combined genetic single progenitor barcoding using Polylox with Flt3-driven, inducible fate mapping. Key immune cell types, including T and B lymphocytes (lymphocytes), innate lymphocytes (ILC) 1-3, NK cells, and granulocytes and monocytes (myeloid) emerged from Flt3+ hematopoietic progenitors. Barcode analysis revealed that about 75% of Flt3+ hematopoietic progenitors had unipotent fates for lymphocytes, or ILC or myeloid cells, while the remaining fraction showed unprecedented fate combinations for these lineages. Focusing on ILC only, we uncovered clonal fate restriction towards ILC1, or ILC2, or ILC3 in tissues. These data indicate early tissue seeding by progenitors, and further differentiation towards discrete subsets in situ. In addition to these fate analyses, induction of fluorescent marker at this intermediate stage of hematopoiesis showed that Flt3+ progenitors generated a wave of progeny lasting for over one year. The washout of these cells over time provided kinetic data of cell turnover in major immune cell compartments (in the circulation and in tissues) in vivo. In conclusion, we tracked the fate of large numbers (in the order of hundreds) of Flt3+ progenitor clones in situ. These intermediate progenitors downstream of HSC displayed mostly lineage-restricted fates as well as strong fate complexity, thus serving as a source for early tissue seeding and durable immune lineage.

developmental biology↗

bioRxiv2021

Immune competence and spleen size scale with colony status in the naked mole-rat

Naked mole-rats (NM-R; Heterocephalus glaber) live in multi-generational colonies with a social hierarchy, show low cancer incidence and long life-spans. Here we asked if such extreme physiology might have an immune component. The spleen is the largest lymphoid organ and plays an essential role in response to immunological insults and may participate in combating cancer and slowing ageing. We investigated the anatomy, molecular composition and function of the NM-R spleen using RNA-sequencing and histological analysis in healthy animals. We found that spleen size in healthy NM-Rs varies considerably. We therefore classified NM-Rs according to spleen size as NM-Rs with small spleens or enlarged spleens. Animals with enlarged spleens showed potentially better anti-microbial profiles and were much more likely to have a high rank within the colony. Splenomegaly was associated with infection in sick NM-Rs, but not in NM-Rs with enlarged spleens. In all healthy NM-Rs splenic erythropoiesis, megakaryopoiesis and myelopoiesis were increased, but B lymphopoiesis was reduced and splenic marginal zone showed markedly altered morphology when compared to other rodents. However, in NM-Rs lymphocytes were found in secondary sites such as lymph nodes, gut lymphoid nodules and thymus. Thus, the NM-R spleen is a major site of adult hematopoiesis under normal physiological conditions. Overall, the NM-R immune system seems to rely mainly on innate immune responses with a more restricted adaptive immune response. We propose that the anatomical plasticity of the spleen might be regulated by social interaction and gives immunological advantage to increase the life-span of higher ranked animals.

immunology↗

bioRxiv2019

A rule-based data-informed cellular consensus map of the human mononuclear phagocyte cell space

Single-cell genomic techniques are opening new avenues to understand the basic units of life. Large international efforts, such as those to derive a Human Cell Atlas, are driving progress in this area; here, cellular map generation is key. To expedite the inevitable iterations of these underlying maps, we have developed a rule-based data-informed approach to build next generation cellular consensus maps. Using the human dendritic-cell and monocyte compartment in peripheral blood as an example, we performed computational integration of previous, partially overlapping maps using an approach we termed backmapping, combined with multi-color flow-cytometry and index sorting-based single-cell RNA-sequencing. Our general strategy can be applied to any atlas generation for humans and other species.\n\nGraphical Abstract\n\nO_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=110 SRC=\"FIGDIR/small/658179v1_ufig1.gif\" ALT=\"Figure 1\">\nView larger version (18K):\norg.highwire.dtl.DTLVardef@c1b7b2org.highwire.dtl.DTLVardef@32b68org.highwire.dtl.DTLVardef@16e5fcorg.highwire.dtl.DTLVardef@1552028_HPS_FORMAT_FIGEXP M_FIG C_FIG HighlightsO_LIDefining a consensus of the human myeloid cell compartment in peripheral blood\nC_LIO_LI3 monocytes subsets, pDC, cDC1, DC2, DC3 and precursor DC make up the compartment\nC_LIO_LIDistinguish myeloid cell compartment from other cell spaces, e.g. the NK cell space\nC_LIO_LIProviding a generalizable method for building consensus maps for the life sciences\nC_LI

immunology↗

bioRxiv2017

Cellular reprogramming of human monocytes is regulated by time-dependent IL4 signalling and NCOR2

The clinical and therapeutic value of human in vitro generated monocyte-derived dendritic cell (moDC) and macrophages is well established. However, in line with recent findings regarding myeloid cell ontogeny and due to our limited understanding of their physiological counterparts, transcriptional regulation and heterogeneity, the full potential of these important cellular systems is still underestimated.\n\nIn this study, we use cutting edge high-dimensional analysis methods to better understand the transcriptional organization, phenotypic heterogeneity and functional differences between human ex vivo isolated and in vitro generated mononuclear phagocytes with the aim to better realize their full potential in the clinic.\n\nWe demonstrate that human monocytes activated by MCSF or GMCSF most closely resemble inflammatory macrophages identified in vivo, while IL4 signalling in the presence of GMCSF generates moDCs resembling inflammatory DCs in vivo, but not steady state cDC1 or cDC2. Moreover, these reprogramming regimes lead to activated monocytes that present with profoundly different transcriptomic, metabolic, phenotypic and functional profiles. Furthermore, we demonstrate that CD14+ monocytes are integrating multiple exogenous activation signals such as GMCSF and IL4 in a combinatorial and temporal fashion, resulting in a high-dimensional cellular continuum of reprogrammed monocytes dependent on the mode and timing of cytokine exposure. Utilizing nanostraw-based knockdown technology, we demonstrate that the IL4-dependent generation of moDCs relies on the induction, nuclear localization and function of the transcriptional regulator NCOR2.\n\nFinally, we unravel unappreciated heterogeneity within the clinically moDCs population and propose a novel high-dimensional phenotyping strategy to better tailor clinical quality control strategies for patient need and culture conditions to enhance therapeutic outcome.

immunology↗