TGF-β signaling underlies hematopoietic dysfunction and bone marrow failure in Shwachman-Diamond syndrome
Cailin E. Joyce, Assieh Saadatpour, Melisa Ruiz-Gutierrez, Ozge Vargel Bolukbasi, Lan Jiang, Dolly D. Thomas, Sarah Young, Inga Hofmann, Colin A. Sieff, Kasiani C. Myers, Jennifer Whangbo, Towia A. Libermann, Chad Nusbaum, Guo-Cheng Yuan, Akiko Shimamura, Carl D. Novina
Cailin E. Joyce, Assieh Saadatpour, Melisa Ruiz-Gutierrez, Ozge Vargel Bolukbasi, Lan Jiang, Dolly D. Thomas, Sarah Young, Inga Hofmann, Colin A. Sieff, Kasiani C. Myers, Jennifer Whangbo, Towia A. Libermann, Chad Nusbaum, Guo-Cheng Yuan, Akiko Shimamura, Carl D. Novina
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Concise Communication Hematology

TGF-β signaling underlies hematopoietic dysfunction and bone marrow failure in Shwachman-Diamond syndrome

Abstract

Shwachman-Diamond syndrome (SDS) is a rare and clinically heterogeneous bone marrow (BM) failure syndrome caused by mutations in the Shwachman-Bodian-Diamond syndrome (SBDS) gene. Although SDS was described more than 50 years ago, its molecular pathogenesis is poorly understood due, in part, to the rarity and heterogeneity of the affected hematopoietic progenitors. To address this, we used single-cell RNA sequencing to profile scant hematopoietic stem and progenitor cells from patients with SDS. We generated a single-cell map of early lineage commitment and found that SDS hematopoiesis was left-shifted with selective loss of granulocyte-monocyte progenitors. Transcriptional targets of transforming growth factor beta (TGF-β) were dysregulated in SDS hematopoietic stem cells and multipotent progenitors, but not in lineage-committed progenitors. TGF-β inhibitors (AVID200 and SD208) increased hematopoietic colony formation of SDS patient BM. Finally, TGF-β3 and other TGF-β pathway members were elevated in SDS patient blood plasma. These data establish the TGF-β pathway as a candidate biomarker and therapeutic target in SDS and translate insights from single-cell biology into a potential therapy.

Authors

Cailin E. Joyce, Assieh Saadatpour, Melisa Ruiz-Gutierrez, Ozge Vargel Bolukbasi, Lan Jiang, Dolly D. Thomas, Sarah Young, Inga Hofmann, Colin A. Sieff, Kasiani C. Myers, Jennifer Whangbo, Towia A. Libermann, Chad Nusbaum, Guo-Cheng Yuan, Akiko Shimamura, Carl D. Novina

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Figure 4

TGF-β pathway activation through TGF-βR1 suppresses hematopoiesis in SDS BM progenitors.

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TGF-β pathway activation through TGF-βR1 suppresses hematopoiesis in SDS...
(A) Representative images showing DAPI and phospho-SMAD2 staining of primary BM CD34+ cells from adult healthy donor BM and pediatric SDS BM, either untreated or treated with AVID200. Scale bar: 25 µm. (B) Mean intensity of phospho-SMAD2 staining in individual CD34+ nuclei from samples depicted in A. Significance was determined by 2-way ANOVA, with Holm-Sidak’s multiple comparisons test. Error bars indicate minimum and maximum values, excluding outliers that exceed median + 1.5*IQR. **P < 0.01; ***P < 0.001. (C) Mean intensity of phospho-SMAD2 staining in individual CD34+ nuclei in 2 additional pairs of SDS and healthy donor BM samples. Error bars indicate minimum and maximum values, excluding outliers that exceed median + 1.5*IQR. **P < 0.01; ****P < 0.0001. (D) Number of colonies formed by adult healthy donor and pediatric SDS patient BM-derived mononuclear cells with increasing concentrations of AVID200, normalized to the 0 μM treatment. Significance was determined relative to the 0 μM treatment by 2-way ANOVA, with Holm-Sidak’s multiple comparisons test. Error bars indicate SEM. *P < 0.05; **P < 0.01. (E) Model for the role of TGF-β signaling in SDS BM failure. TGF-β1 and/or TGF-β3 ligands (targets of AVID200 inhibitor) activate signaling through the TGF-βR1 receptor (target of SD208 inhibitor) on SDS HSCs/MPPs. Our data suggest that TGF-β ligands are primarily derived from a CD34– cell type in BM because TGF-β ligand mRNAs were not detected in CD34+ HSPCs. Increased TGF-βR1 signaling leads to increased concentrations of nuclear phospho-SMAD2 and transcription of inflammatory response genes, which impairs HSC/MPP function. This model predicts that therapeutic inhibition of TGF-β signaling in HSCs/MPPs will improve hematopoietic function in patients with SDS. (F) Expression of extracellular proteins annotated to a TGF-β network that was enriched among dysregulated proteins in SDS patient plasma.