Biglycan as a mediator of proinflammatory response and target for MDS and sAML therapy

ABSTRACT

Myelodysplastic syndromes (MDS) and their progression to secondary acute myeloid leukemia (sAML) are associated with an altered protein expression including extracellular matrix (ECM) components thereby promoting an inflammatory environment. Since the role of the proteoglycan biglycan (BGN) as an inflammatory mediator has not yet been investigated in both diseases and might play a role in disease progression, its expression and/or function was determined in cell lines and bone marrow biopsies (BMBs) of MDS and sAML patients and subpopulations of MDS stem cells by Western blot and immunohistochemistry. The bone marrow (BM) microenvironment was analyzed by multispectral imaging, patients’ survival by Cox regression. ROC curves were assessed for diagnostic value of BGN. All cell lines showed a strong BGN surface expression in contrast to only marginal expression levels in mononuclear cells and CD34⁺ cells from healthy donors. In the MDS-L cell line, CD34⁻CD33⁺ and CD34⁺CD33⁺ blast subpopulations exhibited a differential BGN surface detection. Increased BGN mediated inflammasome activity of CD34⁻CD33⁺TLR4⁺ cells was observed, which was inhibited by direct targeting of BGN or NLRP3. BGN was heterogeneously expressed in BMBs of MDS and sAML, but was not detected in control biopsies. BGN expression in BMBs positively correlated with MUM1⁺ and CD8⁺, but negatively with CD33⁺TLR4⁺ cell infiltration and was accompanied by a decreased progression-free survival of MDS patients. BGN-mediated inflammasome activation appears to be a crucial mechanism in MDS pathogenesis implicating its use as suitable biomarker and potential therapeutic target.

Abbreviations: Ab, antibody; alloSCT, allogenic stem cell transplant; AML, acute myeloid leukemia; BGN, biglycan; BM, bone marrow; BMB, bone marrow biopsy; casp1, caspase 1; CTLA-4, cytotoxic T lymphocyte-associated protein 4; DAMP, danger-associated molecular pattern; ECM, extracellular matrix; FCS, fetal calf serum; GAPDH, glyceraldehyde-3-phosphate dehydrogenase; HD, healthy donor; HSPC, hematopoietic stem and progenitor cell; HSC, hematopoietic stem cell; IFN, interferon; IHC, immunohistochemistry; IL, interleukin; MDS, myelodysplastic syndrome; MPN, myeloproliferative neoplasm; MSI, multispectral imaging; NGS, next-generation sequencing; NLRP3, NLR family pyrin domain containing 3; OS, overall survival; PBMC, peripheral blood mononuclear cell; PD-1, programmed cell death protein 1; PD-L1, programmed death-ligand 1, PFS, progression-free survival; PRR, pattern recognition receptor; SC, stem cell; SLRP, small leucine-rich proteoglycan; TGF, transforming growth factor; TIRAP, toll/interleukin 1 receptor domain-containing adapter protein; TLR, toll-like receptor; Treg, regulatory T cell.

KEYWORDS:

• AML
• MDS
• extracellular matrix
• biglycan
• inflammasome

Data availability statement

The data that support the findings of this study are available from the corresponding author, BS, upon reasonable request ([email protected]).

Acknowledgments

We would like to thank Maria Heise and Nicole Ott for their excellent secretarial help.

Disclosure statement

The authors declare that they have no conflicts of interest.

Author contribution

The corresponding author did ensure that the descriptions are accurate and all authors agreed on the final version of the manuscript. Christoforos Vaxevanis was involved in the design and execution of the experiments and writing the original draft. Marcus Bauer collected clinical and pathological data, performed the MSI analyses, Karthik Subbarayan performed the Western blot and qPCR analysis, Michael Friedrich and Chiara Massa were discussing the experimental outline and worked on the manuscript, Katharina Biehl performed sample preparation and staining for MSI analysis, Claudia Wickenhauser provided study materials and reviewed the manuscript. Barbara Seliger was mentoring the team, coordinated the manuscript, wrote together with Christoforos Vaxevanis the original draft and is responsible for the final version of this manuscript.

Supplementary material

Supplemental data for this article can be accessed online at https://doi.org/10.1080/2162402X.2022.2152998

Additional information

Funding

This work was supported by the Wilhelm-Roux-Program of the Medical Faculty of the MLU (CW) and Sander grant (2019.076.1, BS)..