Apremilast for moderate hidradenitis suppurativa: no significant change in lesional skin inflammatory biomarkers.

BACKGROUND: Treatment with apremilast has recently demonstrated clinically meaningful improvement in moderate hidradenitis suppurativa (HS). OBJECTIVE: To evaluate the change in expression of inflammatory markers in lesional skin of HS patients receiving apremilast 30 mg twice daily (n = 15) for 16 weeks compared with placebo (n = 5). METHODS: At baseline, 5-mm punch biopsies were obtained from an index lesion (HSL) and non-lesional (HSN) skin in the same anatomical area. Subsequent HSL samples were taken as close as possible to the previously biopsied site at week 4 and week 16. After sampling, biopsies were split; one half was processed for in vivo mRNA analysis using real-time quantitative PCR; the other half was cultured for ex vivo protein analysis using a proximity extension assay (Olink). Linear mixed effects models were calculated to compare the levels of inflammatory markers in HSL skin between apremilast and placebo over time. RESULTS: At baseline, 17 proteins with a fold change >2 in HSL vs. HSN skin were identified in 20 patients. The top five were IL-17A (5), S100A12, CST5, IL-12/23p40, CD6 (1) with fold changes ranging from 6.6 to 1638, respectively (FDR <0.044). Linear mixed effects models for 75 assays were calculated. Protein levels of S100A12 decreased during treatment in the apremilast group compared with the placebo group (p = 0.014, FDR = 0.186). None of the 14 genes exhibited significant changes in expression over time. However, an evident downward trend in relative mRNA expression of IL-17A and IL-17F was demonstrated in patients receiving apremilast. CONCLUSION: We did not detect statistically significant changes in inflammatory markers in HSL skin of HS patients receiving apremilast compared with placebo, despite clinical improvement in the apremilast group. Nonetheless, S100A12 and IL-17A were significantly elevated in HSL skin and showed a decrease in response to apremilast. The translational model in clinical trials involving HS clearly needs further improvement.

Th17 cells, but not Th1 cells, from patients with early rheumatoid arthritis are potent inducers of matrix metalloproteinases and proinflammatory cytokines upon synovial fibroblast interaction, including autocrine interleukin-17A production.

OBJECTIVE: Both Th1 cells and Th17 cells have been recognized in rheumatoid arthritis (RA); however, it remains unclear whether Th1 cells and/or Th17 cells are involved in driving disease chronicity and destructiveness. The aim of this study was to identify and characterize the functional role of Th17 cells in early RA. METHODS: Flow cytometry analysis was performed on peripheral blood mononuclear cells (PBMCs) from treatment-naive patients with early RA and age-matched healthy volunteers. PBMCs from these patients, naive T cells, and primary CCR6- Th1 cells and CCR6+ Th17 cells were sorted and cultured in the absence or presence of synovial fibroblasts from patients with early RA (RASFs), and cytokine expression and gene transcription were analyzed. In addition, tumor necrosis factor α (TNFα)- and interleukin-17A (IL-17A)-blocking experiments were performed. RESULTS: In the PBMCs of treatment-naive patients with early RA, an increased fraction of IL-17A-and TNFα-producing CCR6+ Th17 cells was observed. When cocultured with RASFs, these primary Th17 cells were potent inducers of IL-6 and IL-8 and the tissue-destructive enzymes matrix metalloproteinase 1 (MMP-1) and MMP-3, whereas primary Th1 cells or naive T cells were not. Importantly, specific up-regulation of IL-17A but not TNFα or interferon-γ was observed in RASF/Th17 cell cocultures. In addition to TNFα blocking, IL-17A neutralization was required to further down-regulate Th17 activity in RASF/Th17 cell cocultures. CONCLUSION: Th17 cells, but not Th1 cells, cooperated with RASFs in a proinflammatory feedback loop, revealing a potential mechanism by which human Th17 cells drive chronic destructive disease in patients with RA. Furthermore, the neutralization of IL-17A activity is essential in current anti-TNF therapies to suppress Th17 cell activity in patients with early RA and potentially other Th17 cell-mediated disorders.