Single-cell mass cytometry reveals cross-talk between inflammation-dampening and inflammation-amplifying cells in osteoarthritic cartilage

Abstract

Aging or injury leads to degradation of the cartilage matrix and the development of osteoarthritis (OA). Because of a paucity of single-cell studies of OA cartilage, little is known about the interpatient variability in its cellular composition and, more importantly, about the cell subpopulations that drive the disease. Here, we profiled healthy and OA cartilage samples using mass cytometry to establish a single-cell atlas, revealing distinct chondrocyte progenitor and inflammation-modulating subpopulations. These rare populations include an inflammationamplifying (Inf-A) population, marked by interleukin-1 receptor 1 and tumor necrosis factor receptor II, whose inhibition decreased inflammation, and an inflammation-dampening (Inf-D) population, marked by CD24, which is resistant to inflammation. We devised a pharmacological strategy targeting Inf-A and Inf-D cells that significantly decreased inflammation in OA chondrocytes. Using our atlas, we stratified patients with OA in three groups that are distinguished by the relative proportions of inflammatory to regenerative cells, making it possible to devise precision therapeutic approaches. RESULTS High-dimensional mass cytometry-based profiling of normal and OA cartilageToward our goal of profiling rare stem/progenitor-like populations within normal and OA cartilage, we used cyTOF, a mass spectrometrybased high-dimensional method for single-cell detection of isotopelabeled antibodies (Fig. 1A) (8). While cyTOF panels have to be preselected for each experiment, this technique provides the advantage , Single-cell mass cytometry reveals cross-talk between inflammation-dampening and inflammation-amplifying cells in osteoarthritic cartilage.

Two reactive behaviors of chondrocytes in an IL-1β-induced inflammatory environment revealed by the single-cell RNA sequencing

“…Together with the gradual increase in expression levels observed for well-known pro-inflammatory genes from the original clusters to cluster 0, the response-to-inflammation pathway appears to reflect transcription variations that underlie inflammatory progression. This finding is partly consistent with the findings of a more recent study [ 39 ] in which Grandi et al identified two rare inflammation-modulating subpopulations, one of which was defined as an inflammation-amplifying population, characterized by the increased expression of IL-1 receptor 1 and TNF receptor II. Although the specific inflammatory molecules between these two studies differ, our study can be viewed as complementary evidence regarding an inflammation-specific subpopulation of chondrocytes when cultured in vitro and revealing the transcript signatures associated with changes in chondrocyte physiology.…”

Gene Expression Signatures of Synovial Fluid Multipotent Stromal Cells in Advanced Knee Osteoarthritis and Following Knee Joint Distraction

“…Our chondrocyte cultures were derived from full-depth OA cartilage and grown in culture media different from MSC-expansion media; this could have partially contributed to differences in their gene expression compared with MSCs. Similarly, single-cell RNA sequencing (Ji et al, 2019) or mass cytometry (Grandi et al, 2020) on cartilage-resident cells including uncultured CPCs and comparing their profiles with single MSCs would provide future valuable insights into different progenitor and stem cell types present in OA-affected human joints. If cultured, the same early passage cells should be used for transcript analysis and functional assays.…”

Single-Nucleus Transcriptomic Analysis Reveals Important Cell Cross-Talk in Diabetic Kidney Disease

“…Single-cell sequencing (scRNA-seq) is a technological evolution and provides unprecedented insight into cell communication (10)(11)(12). In experimental studies of renal diseases (13)(14)(15)(16), scRNA-seq technology furthers the understanding of the mechanisms and cell-to-cell interactions involved in disease pathogenesis.…”