{
  "abstract": "Introduction Macrophages play a major role in dcSSc-related skin fibrosis, with a mixed M1-M2 activation profile relying on the activation of JAK/STAT pathways. Tofacitinib, a pan-JAK inhibitor, down regulates interferon (IFN) in human fibroblasts, and modulates macrophage activation profile in SSc mouse models. Its impact on human skin macrophages in dcSSc has not be studied. The objectives of our study were to identify macrophage subpopulations overrepresented in early dcSSc, and to assess the impact of tofacitinib on these subsets utilizing skin biopsies from a randomized controlled phase I/II trial (RCT : NCT03274076).Material and Methods Single cell RNA sequencing (scRNAseq) of skin biopsies from 14 healthy donors (HD) were compared to skin biopsies from 26 early dcSSc to identify overrepresented macrophages sub populations in dcSSc. In addition, data from a phase I/II RCT were utilized to evaluate the impact of tofacitinib on identified macrophage populations : skin biopsies of 10 dcSSc patients receiving tofacitinib were assessed at baseline and at week 6 and were compared to skin biopsies from 5 dcSSc patients receiving placebo using scRNAseq. Impact on identified markers was secondly confirmed using qPCR in M-CSF monocytes-derived-macrophages (MDM) from HD treated in vitro by tofacitinib in resting or in IL4/IL13 polarized conditions, and ex vivo experiments where skin biopsies from dcSSc patients were treated by tofacitinib in-vitro and analysed by scRNAseq (n=3).Results 7 clusters of myeloid cells (1 Langerhans cell cluster, 4 dendritic cell clusters, 1 monocyte cluster and 2 macrophage clusters) were identified from skin biopsies by scRNAseq. Macrophage cluster 1 and CCR7-positive conventional DC were overrepresented in the skin of dcSSc patients as compared to HD. Macrophage cluster 1 was characterized by the expression of CCL18, HMOX1 and CCL13. In the RCT, HMOX1 and CCL13 were both significantly down regulated by tofacitinib whereas no significant down regulation was observed in the placebo group. HMOX1 expression at baseline in this macrophage cluster also correlated with JAK/STAT-dependent IL4/IL13 pathways. In vitro treatment of MDM by tofacitinib confirmed the significant down regulation of CCL13 and HMOX1 in a dose dependent manner. Ex vivo experiments also confirmed the decrease % of CCL13 and HMOX1 positive macrophages after treatment by tofacitinib as compared to treatment of the biopsies from the same patients with DMSO.Conclusions We identified a cluster of macrophages overrepresented in the skin of dcSSc using scRNAseq and characterized by the expression of CCL13 and HMOX1, which were both down-regulated by tofacinitib in dcSSc.",
  "authors": [
    {
      "affiliations": [
        "CHU Rennes, Pole Biologie - SITI - EFS, Rennes, France",
        "Equal contribution, * Other"
      ],
      "name": "Juliette Ferrant"
    },
    {
      "affiliations": [
        "Department of Internal Medicine, CHU Rennes, Univ Rennes, Rennes, France",
        "UMR_1085 IRSET, Univ Rennes, Rennes, France",
        "Department of Rheumatology, University of Michigan, Ann Arbor, USA",
        "Equal contribution, * Other"
      ],
      "name": "Alain Lescoat"
    },
    {
      "affiliations": [
        "UMR_1085 IRSET, Univ Rennes, Rennes, France"
      ],
      "name": "Valérie Lecureur"
    },
    {
      "affiliations": [
        "UMR_1085 IRSET, Univ Rennes, Rennes, France"
      ],
      "name": "Marie Lelong"
    },
    {
      "affiliations": [
        "Department of Rheumatology, University of Michigan, Ann Arbor, USA"
      ],
      "name": "John Varga"
    },
    {
      "affiliations": [
        "Division of Rheumatology and Clinical Immunology, University of Pittsburgh, Pittsburgh, USA"
      ],
      "name": "Robert Lafyatis"
    },
    {
      "affiliations": [
        "Department of Dermatology, University of Michigan, Ann Arbor, USA"
      ],
      "name": "Johann E Gudjonsson"
    },
    {
      "affiliations": [
        "Department of Rheumatology, University of Michigan, Ann Arbor, USA"
      ],
      "name": "Dinesh Khanna"
    }
  ],
  "title": "OC.28 Skin macrophage subtypes and impact of tofacitinib in early diffuse cutaneous systemic sclerosis: results from combined single-cell analyses of an observational data set and a phase I/II randomized co",
  "uid": "eef4f803-122e-5eda-96ad-4edbed7855bd"
}