title: Bone remodeling in psoriasis and psoriatic arthritis: an update.
abstract: OBJECTIVE
  This article reviews and outlines recent advances in the field of bone remodeling in psoriatic disease and identify avenues for further research.
  
  
  RESULTS
  High-resolution imaging revealed that new bone formation, observed in psoriatic arthritis (PsA) is centered at enthesial sites in contrast to hand osteoarthritis, and new bone formation is also present in psoriasis patients without arthritis. Accumulating evidence strongly suggests that the IL-23/IL-17 pathway is directly involved in altered bone phenotypes in PsA. Apart from Th17 and Th22 cells, CD8IL-17 T cells, γδT cells, and type 3 innate lymphoid cells also secrete IL-17 and IL-22. Further studies will be needed to clarify the role of these cells in bone remodeling in the context of psoriatic disease. Recent research also strengthened the earlier viewpoint that mechanical stress can serve as a trigger for joint inflammation and arthritis development. Recent findings suggest that inflammation beginning in the skin may become more generalized and involve musculoskeletal structures. Other reports suggest that gut microbiota might have a role in joint inflammatory responses and bone remodeling in psoriatic disease. Successful application of omics approaches and advance imaging studies also revealed many novel aspects of psoriatic diseases and joint-related pathologies which will likely help pinpoint causal genes, pathways, and novel biomarkers in the near future.
  
  
  CONCLUSIONS
  Imaging studies have provided new insights into new bone formation phenotypes in PsA. The IL-23/IL-17 pathway is of central importance in psoriatic bone remodeling where, apart from CD4 T helper cells, other IL-17 and IL-22-secreting innate and adaptive cells may also be involved. Insights from study of the microbiome and from omics technologies will set the stage for new advances in our understanding of bone disorders in psoriatic diseases.
authors.affiliation: Allergy, Immunology and Rheumatology Division, University of Rochester Medical Center, Rochester, New York, USA.
authors.forename: Ananta
authors.initials: A
authors.lastname: Paine
authors.forename: Christopher
authors.initials: C
authors.lastname: Ritchlin
mesh_terms: D015535:Arthritis, Psoriatic / Q000276:immunology*; D016723:Bone Remodeling / Q000276:immunology*; D016207:Cytokines / Q000276:immunology; D006801:Humans; D020381:Interleukin-17 / Q000276:immunology; D053759:Interleukin-23 / Q000276:immunology; D007378:Interleukins / Q000276:immunology; D011565:Psoriasis / Q000276:immunology; D000097043:Interleukin-22
chemical_list: D016207:Cytokines; D020381:Interleukin-17; D053759:Interleukin-23; D007378:Interleukins; D000097043:Interleukin-22