BACKGROUND/AIMS: The aim of this study was to identify the profile of rare variants associated with Crohn's disease (CD) using whole exome sequencing (WES) analysis of Korean children with CD and to evaluate whether genetic profiles could provide information during medical decision making. METHODS: DNA samples from 18 control individuals and 22 patients with infantile, very-early and early onset CD of severe phenotype were used for WES. Genes were filtered using panels of inflammatory bowel disease (IBD)-associated genes and genes of primary immunodeficiency (PID) and monogenic IBD. RESULTS: Eighty-one IBD-associated variants and 35 variants in PID genes were revealed by WES. The most frequently occurring variants were carried by nine (41%) and four (18.2%) CD probands and were ATG16L2 (rs11235604) and IL17REL (rs142430606), respectively. Twenty-four IBD-associated variants and 10 PID variants were predicted to be deleterious and were identified in the heterozygous state. However, their functions were unknown with the exception of a novel p.Q111X variant in XIAP (X chromosome) of a male proband. CONCLUSIONS: The presence of many rare variants of unknown significance limits the clinical applicability of WES for individual CD patients. However, WES in children may be beneficial for distinguishing CD secondary to PID.
Asian Continental Ancestry Group/genetics ; Carrier Proteins/genetics ; Child ; Child, Preschool ; Crohn Disease/*genetics ; *Exome ; Female ; Genetic Predisposition to Disease ; *Genetic Variation ; Humans ; Immunologic Deficiency Syndromes/genetics ; Infant ; Male ; Phenotype ; Receptors, Interleukin-17/genetics ; Republic of Korea ; Sequence Analysis, DNA/*methods ; X-Linked Inhibitor of Apoptosis Protein/genetics

IL-17-producing CD4+ T cells (Th17) play important functions in autoimmune diseases and allograft rejection of solid organs. We examined the effects of IL 17 and its mechanism of action on arthritis in a murine collagen-induced arthritis (CIA) model using bone marrow transplantation (BMT) system. DBA/1J mice were administered a lethal radiation dose and then rescued with bone marrow derived from either wild-type (WT) or IL-17-/- mice on C57BL/6 background mice. CIA was induced after the bone marrow transplant, and disease progression was characterized. DBA/1J mice with CIA that received IL-17-/- donor bone marrow showed potently inhibited development and severity of clinical arthritis as compared with CIA mice that received WT bone marrow. Reduced secretion of the pro-inflammatory cytokines tumor necrosis factor-alpha, IL-1beta, and IL-6, and collagen-specific T cell responses were observed in mice that received IL-17-/- bone marrow. IL-17 blockade also inhibited effector T cell proliferation by reciprocally regulating the Treg/Th17 ratio. IL-17 blockade prevented joint destruction in mice with CIA. These findings suggest that CIA with BMT is a viable method of immunological manipulation and that IL-17 deficiency suppresses severe joint destruction and inflammation in CIA mice. There may be clinical benefits in blocking IL-17 and BMT in the treatment of rheumatoid arthritis.
Animals ; Antigens, Differentiation/metabolism ; Arthritis, Experimental/pathology/*prevention & control ; *Bone Marrow Transplantation ; Cell Differentiation ; Cell Proliferation ; Cells, Cultured ; Collagen Type II ; Cytokines/metabolism ; Humans ; Interleukin-17/*deficiency/genetics ; Joints/pathology ; Male ; Mice ; Mice, Inbred C57BL ; Mice, Inbred DBA ; Mice, Knockout ; Osteoclasts/metabolism/physiology ; Signal Transduction ; T-Lymphocytes/metabolism/physiology ; Transplantation, Homologous