title: Interleukin 23-Helper T Cell 17 Axis as a Treatment Target for Pityriasis Rubra Pilaris.
abstract: OBJECTIVE
  Treatment of pityriasis rubra pilaris (PRP) is solely based on its resemblance to psoriasis rather than any knowledge of its pathomechanism. Insight into pathogenic mediators of inflammation is essential for targeted and valid treatment options that could replace previous serendipitous therapeutic approaches in refractory PRP.
  
  
  OBJECTIVE
  To determine whether blockade of the interleukin 23-helper T cell 17 (IL-23-TH17) pathway with ustekinumab represents an efficacious and, based on its proinflammatory cytokine profile, targeted treatment option in PRP.
  
  
  METHODS
  In this case report, a patient with PRP received outpatient treatment at a university hospital department of dermatology with ustekinumab according to the dosing regimen approved for psoriasis. Lesional skin biopsy samples were taken from this patient and 2 others with refractory PRP. Messenger RNA (mRNA) expression of proinflammatory innate and T-cell-derived cytokines were measured and compared with skin samples from patients with psoriasis and healthy donors. From 1 patient, lesional skin samples were taken before ustekinumab treatment and 4 and 28 weeks after treatment initiation. Follow-up was completed after 6 months.
  
  
  METHODS
  Subcutaneous ustekinumab, 45 mg, at weeks 0 and 4 and quarterly thereafter.
  
  
  METHODS
  The primary outcome was to determine the changes in expression of proinflammatory innate and T-cell-derived cytokines during ustekinumab therapy. The secondary objective was to evaluate the clinical and histopathologic phenotype in relation to the mRNA expression profile of proinflammatory cytokines.
  
  
  RESULTS
  In lesional PRP skin samples from a single patient, upregulated expression levels were found for most proinflammatory innate cytokines, including tumor necrosis factor (TNF), IL-6, IL-12, IL-23, and IL-1β. Among adaptive T-cell cytokines, an increase of TH1 cytokines and, in particular, TH17 cytokines IL-17A, IL-17F, and IL-22 was seen in PRP. The patient with PRP who received ustekinumab showed regression of skin lesions after 2 weeks and almost complete resolution after 1 month. Clinical and histopathologic improvement paralleled the expression levels of TH17 cytokines but not of interferon-γ and TNF, which lagged behind the amelioration.
  
  
  CONCLUSIONS
  In this case report, a role of the IL-23-TH17-axis in PRP was identified, suggesting a shared pathogenic inflammatory pathway with psoriasis, despite evident clinical and histopathologic differences. In addition, this report provides a rationale for targeting the IL-23-TH17-pathway as a treatment option for refractory PRP.
authors.affiliation: Department of Dermatology and Venereology, University Hospital of Lausanne, Centre Hospitalier Universitaire Vaudois, Lausanne, Switzerland2Department of Dermatology and Venereology, Inselspital Bern University Hospital, University of Bern, Bern, Switzerland.
authors.forename: Laurence
authors.initials: L
authors.lastname: Feldmeyer
authors.affiliation: Department of Dermatology and Venereology, University Hospital of Lausanne, Centre Hospitalier Universitaire Vaudois, Lausanne, Switzerland.
authors.forename: Alessio
authors.initials: A
authors.lastname: Mylonas
authors.affiliation: Department of Dermatology and Venereology, University Hospital of Lausanne, Centre Hospitalier Universitaire Vaudois, Lausanne, Switzerland.
authors.forename: Olivier
authors.initials: O
authors.lastname: Demaria
authors.affiliation: Department of Dermatology and Venereology, University Hospital of Lausanne, Centre Hospitalier Universitaire Vaudois, Lausanne, Switzerland.
authors.forename: Anna
authors.initials: A
authors.lastname: Mennella
authors.affiliation: Department of Dermatology and Venereology, Inselspital Bern University Hospital, University of Bern, Bern, Switzerland.
authors.forename: Nikhil
authors.initials: N
authors.lastname: Yawalkar
authors.affiliation: Department of Dermatology and Venereology, Geneva University Hospitals, Geneva, Switzerland.
authors.forename: Emmanuel
authors.initials: E
authors.lastname: Laffitte
authors.affiliation: Department of Dermatology and Venereology, University Hospital of Lausanne, Centre Hospitalier Universitaire Vaudois, Lausanne, Switzerland.
authors.forename: Daniel
authors.initials: D
authors.lastname: Hohl
authors.affiliation: Department of Dermatology and Venereology, University Hospital of Lausanne, Centre Hospitalier Universitaire Vaudois, Lausanne, Switzerland.
authors.forename: Michel
authors.initials: M
authors.lastname: Gilliet
authors.affiliation: Department of Dermatology and Venereology, University Hospital of Lausanne, Centre Hospitalier Universitaire Vaudois, Lausanne, Switzerland.
authors.forename: Curdin
authors.initials: C
authors.lastname: Conrad
mesh_terms: D000328:Adult; D001706:Biopsy; D016207:Cytokines / Q000235:genetics; D003879:Dermatologic Agents / Q000494:pharmacology / Q000627:therapeutic use*; D005500:Follow-Up Studies; D006801:Humans; D053759:Interleukin-23 / Q000235:genetics*; D008297:Male; D010916:Pityriasis Rubra Pilaris / Q000188:drug therapy* / Q000235:genetics / Q000473:pathology; D011565:Psoriasis / Q000473:pathology; D012333:RNA, Messenger / Q000378:metabolism; D058504:Th17 Cells / Q000378:metabolism*; D013997:Time Factors; D016896:Treatment Outcome; D015854:Up-Regulation; D000069549:Ustekinumab / Q000494:pharmacology / Q000627:therapeutic use*
chemical_list: D016207:Cytokines; D003879:Dermatologic Agents; D053759:Interleukin-23; D012333:RNA, Messenger; D000069549:Ustekinumab