Biology subjects

Wernig, G.

Publications and source records attributed to Wernig, G..

4 recordsLinked to original sources

bioRxiv2021

Integrated spatial multi-omics reveals fibroblast fate during tissue repair

In the skin, tissue injury results in fibrosis in the form of scars composed of dense extracellular matrix deposited by fibroblasts. The therapeutic goal of regenerative wound healing has remained elusive in part because principles of fibroblast programming and adaptive response to injury remain incompletely understood. Here, we present a multimodal -omics platform for the comprehensive study of cell populations in complex tissue, which has allowed us to characterize the cells involved in wound healing across both time and space. We employ a stented wound model that recapitulates human tissue repair kinetics and multiple Rainbow transgenic lines to precisely track fibroblast fate during the physiologic response to injury. Through integrated analysis of single cell chromatin landscapes and gene expression states, coupled with spatial transcriptomic profiling, we are able to impute fibroblast epigenomes with temporospatial resolution. This has allowed us to define the mechanisms controlling cell fate during migration, proliferation, and differentiation following tissue injury and thereby reexamine the canonical phases of wound healing. These findings have broad implications for the study of tissue repair in complex organ systems.

bioinformatics↗

bioRxiv2020

Tuning TPO-R signaling to influence hematopoietic stem cell differentiation and inhibit essential thrombocythemia

Thrombopoietin (TPO) and the TPO-receptor (TPO-R, or c-MPL)) are essential for hematopoietic stem cell (HSC) maintenance and megakaryocyte differentiation. Agents that can modulate TPO-R signaling are highly desirable, both experimentally and clinically. We have developed a series of surrogate protein-ligands for TPO-R, in the form of diabodies, that homodimerize the TPO-R on the cell surface in different geometries, in effect tuning downstream signaling responses. These surrogate ligands exhibit diverse pharmacological properties, inducing graded signaling outputs, from full to partial TPO agonism and antagonism, thus decoupling the dual functions of TPO/TPO-R. Using scRNA sequencing and HSC self-renewal assays we find that partial agonistic diabodies preserved the stem-like properties of cultured HSCs, but also blocked oncogenic colony formation in Essential Thrombocythemia (ET) through inverse agonism. Our data suggest that dampening downstream TPO signaling is a powerful approach not only for HSC preservation in culture, but also for inhibiting oncogenic signaling through the TPO-R. Significance StatementThe TPO cytokine, which signals through its receptor c-MPL (or TPO-R), is essential for megakaryocyte differentiation and maintenance of hematopoietic stem cells (HSCs). Its signaling is deregulated in Essential Thrombocythemia (ET). Here, we engineered diabodies (DBs) against the TPO-R as surrogate TPO ligands to manipulate TPO-R signaling, from full to partial to antagonism, thus decoupling the dual functions of TPO/TPO-R (i.e, HSC maintenance versus megakaryopoiesis). We subsequently discovered that partial agonistic DBs, by reducing the strength of the TPO-R signal, not only preserved HSCs in culture, but also blocked oncogenic signaling in ET. This finding has the potential to improve HSC cultures for transplants, as well as serve as a unique therapeutic approach for ET.

cell biology↗

bioRxiv2020

CD47 prevents the elimination of diseased fibroblasts in scleroderma

Scleroderma is a devastating fibrotic autoimmune disease. Current treatments are partly effective in preventing disease progression, but do not remove fibrotic tissue. Here, we evaluated whether scleroderma fibroblasts take advantage of the "dont-eat-me-signal" CD47 and whether blocking CD47 enables the bodys immune system to get rid of diseased fibroblasts. To test this approach, we used a Jun-inducible scleroderma model. We first demonstrated in patient samples that scleroderma upregulated JUN and increased promotor accessibilities of both JUN and the CD47. Next, we established our scleroderma model demonstrating that Jun mediated skin fibrosis through the hedgehog-dependent expansion of CD26+Sca1-fibroblasts in mice. In a niche-independent adaptive transfer model, JUN steered graft survival and conferred increased self-renewal to fibroblasts. In vivo, JUN enhanced the expression of CD47, and inhibiting CD47 eliminated an ectopic fibroblast graft and increased in vitro phagocytosis. In the syngeneic mouse, depleting macrophages ameliorated skin fibrosis. Therapeutically, combined CD47 and IL6 blockade reversed skin fibrosis in mice and led to the rapid elimination of ectopically transplanted scleroderma cells. Altogether, our study is the first to demonstrate the efficiency of combining different immunotherapies in treating scleroderma and provide a rationale for combining CD47 and IL6 inhibition in clinical trials.

immunology↗

bioRxiv2020

Activation of JUN in fibroblasts promotes pro-fibrotic programme and modulates protective immunity

In pulmonary fibrosis, the transcription factor JUN is highly expressed in the fibrotic foci. Its induction in adult mice drives lung fibrosis, which is abrogated by administration of anti-CD47. Here, we use high-dimensional mass cytometry to profile protein expression and the secretome of individual fibroblasts and leukocytes from pulmonary fibrosis patients. We show that JUN is activated in fibroblasts derived from fibrotic lungs which also demonstrated increased CD47 and PD-L1 expression. Using ATAC-seq and ChIP-seq, we found that activation of JUN in fibroblasts rendered enhancers of CD47 and PD-L1 accessible, an observation that reporter assays corroborated. Meanwhile we detected increased IL-6 signaling which amplified both JUN-mediated CD47-enhancer activity and protein expression in fibrotic lung fibroblasts. Using an in vivo mouse model of fibrosis, we found two distinct mechanisms by which blocking IL-6, CD47, and PD-L1 reversed fibrosis--increased phagocytosis of profibrotic fibroblasts and elimination of suppressive effects on adaptive immunity. Our results identify specific immune mechanisms that promote the fibrotic process and suggest a complementary therapeutic approach that could be used alongside conventional anti-fibrotics for pulmonary fibrosis diseases.

immunology↗