Clinical and Molecular Phenotyping in Scleromyxedema Pretreatment and Posttreatment With Intravenous Immunoglobulin

Abstract

Objective: Scleromyxedema (SMX) is a rare systemic sclerosis mimic that often responds to intravenous immunoglobulin (IVIG) therapy, yet the resulting clinical and biochemical changes have not been well characterized. To better understand the pathogenesis of the disease and the efficacy of IVIG, we sought to explore whether IVIG would introduce a measurable biologic effect corresponding with clinical improvement.

Methods: Fifteen patients with SMX were recruited for the study. Clinical information and peripheral blood mononuclear cells for flow cytometry were obtained immediately before and again 1-2 weeks after patients received IVIG therapy. Ten patients also underwent skin biopsies for gene expression analysis both before and after IVIG therapy. Clinical data included measures of skin involvement (modification of the modified Rodnan skin thickness score [MMRSS] and percentage of body surface area) and several patient-reported outcome measures assessing patients' skin.

Results: Posttreatment, the average MMRSS score decreased from mean ± SD 13.6 ± 2.6 to 10.3 ± 1.9; P = 0.003. There were also significant improvements in skin flexibility (mean ± SD 5.4 ± 0.8 to 3.2 ± 0.7; P = 0.003) and softening (mean ± SD 4.9 ± 0.9 to 2.6 ± 0.6; P = 0.022). Baseline levels of Tc17 cells (CD8+CCR6+CXCR3+CCR4-) correlated with the extent of skin involvement as measured by MMRSS pretreatment (r = 0.69, P = 0.012) and decreased after IVIG therapy (mean ± SD 3.4% ± 3.2% to 1.3% ± 1.7%; P = 0.008). Posttreatment analysis of RNA in skin tissue revealed a decrease in gene expression of transforming growth factor β (TGFβ) cytokines as well as several interferon-inducible proteins.

Conclusion: This open-label study further supports the evidence that patients with SMX respond both objectively and subjectively to IVIG therapy. Biologic studies suggest a role for T lymphocytes in the pathogenesis of the disease and reveal the potential significance of TGFβ and interferon pathways.

Figure 1.

Microarray gene expression analysis volcano plot where the x-axis depicts differential expression as log2 fold change, and the Y-axis statistical significance as –log¹⁰ p-value. Pathway analysis detected a decrease in chemotaxis and cell movement in granulocytes and agranulocytes post-IVIG treatment. Related genes on the left (in blue boxes) represent those that significantly decreased post-IVIG treatment by a fold change of >2SD. The single gene in the red box represents the sole gene whose expression was significantly increased after treatment. LILRB3: Leukocyte immunoglobulin-like receptor subfamily B, ACKR2: atypical chemokine receptor 2, SERPINA1: Serpin Family A Member 1, FGR: Gardner-Rasheed feline sarcoma viral oncogene homolog, FLOT1: Flotillin 1, SPHK1: sphingosine kinase 1, CMKLR1: Chemokine like receptor 1; CCL21: chemokine ligand 25, CSF3R: colony stimulating factor 3 receptor, JAML: Junction Adhesion Molecule Like, PPBP: pro-platelet basic protein, CCL5: chemokine ligand 5, CSF1R: colony stimulating factor 1 receptor, GREM1: Gremlin 1, HCK: hematopoetic cell kinase, GPSM3: G-protein signaling modulator 3, G6PC3: glucose-6-phosphatase 3, SHC1: SHC adaptor protein 1, SLAMF8: SLAM family member 8, PIP5K1C: phosphatidylinositol 4-phosphate 5-kinase, MYO9B: myosin IXB, SPI1: Spi-1 Proto-Oncogene, SPHK2: Sphingosine Kinase 2, FPR1: Formyl peptide receptor 1, IL4R: interleukin 4 receptor, SELP: Selectin P, S100A12: S100 calcium-binding protein A12, NCKAP1L: NCK Associated Protein 1 Like, PTGES: prostaglandin E synthase, ANGPT2: angiopoietin 2, PTPN6: Tyrosine-protein phosphatase non-receptor type 6, AIF1: Allograft inflammatory factor 1, MYO1F: myosin IF, PIK3CG: Phosphatidylinositol-4,5-Bisphosphate 3-Kinase Catalytic Subunit Gamma, TRPM2: Transient receptor potential cation channel, subfamily M, member 2, CCL28: C-C Motif Chemokine Ligand 28.

Figure 2.

Ingenuity Pathway Analysis of TGFβ signaling throughout different cellular compartments. In the extracellular space, TGFβ cytokines including TGFβ1–3 and BMP 2, 4, and 7 were down-regulated post-IVIG. Predicted downstream effects are depicted by the arrows. Those genes outlined in purple signify a decrease by >2SD.

Figure 3.

Ingenuity Pathway Analysis of hepatic stellate cell activation. Several downstream and nuclear genes are decreased post-IVIG, as indicated by the blue color. Those genes outlined in purple signify a decrease by >2SD.