ABSTRACT
Psoriasis is largely mediated by interleukin (IL)-23/T helper (Th) 17 axis, and IL-21 is a pleiotropic cytokine expressed by Th17 cells. Despite previously reported possible pathogenic roles of IL-21 in human psoriasis, we found that IL-21 receptor (IL-21R) signalling was not crucial for imiquimod-induced psoriatic inflammation, using IL-21R-/- mice. The severity of imiquimod-induced psoriatic manifestation and pro-inflammatory Th17 cytokine levels, IL-17A-producing γδ T cells and CD4+ T cells, and in vitro IL-17A production by γδ T cells after IL-23 stimulation was comparable between wild-type and IL-21R-/- mice. Collectively, IL-21R signalling was not critically involved in IMQ-induced psoriatic inflammation despite an increased IL-21 expression in the IMQ-treated mouse skin. Our data may represent the significant differences between human psoriasis and murine psoriasis model, and further studies using other models will be required to elucidate the role of IL-21 in psoriasis pathogenesis.
Subject(s)
Dermatitis/genetics , Interleukin-21 Receptor alpha Subunit/metabolism , Psoriasis/genetics , Receptors, Interleukin-21/metabolism , Animals , CD4-Positive T-Lymphocytes/cytology , Dermatitis/metabolism , Imiquimod , Inflammation , Interferon Inducers/pharmacology , Interleukin-21 Receptor alpha Subunit/genetics , Interleukin-23 Subunit p19/metabolism , Intraepithelial Lymphocytes/cytology , Mice , Mice, Knockout , Mice, Transgenic , Psoriasis/chemically induced , Psoriasis/metabolism , Receptors, Interleukin-21/genetics , Signal TransductionABSTRACT
A Core Protection Calculator System (CPCS) was developed to initiate a Reactor Trip under the circumstance of certain transients by a Combustion Engineering Company. The major function of the Core Protection Calculator System is to generate contact outputs for the Departure from Nucleate Boiling Ratio (DNBR) Trip and a Local Power Density (LPD) Trip. But in a Core Protection Calculator System, a trip cause cannot be identified, thus only trip signals are transferred to the Plant Protection System (PPS) and only the trip status is displayed. It could take a considerable amount of time and effort for a plant operator to analyze the trip causes of a Core Protection Calculator System. So, a Cause Analysis System for a Core Protection Calculator System (CASCPCS) has been developed by using the rule-base deduction method to assist operators in a Nuclear Power Plant. CASCPCS consists of three major parts. Inference engine has a role of controlling the searching knowledge base, executing the rules and tracking the inference process by using the depth-first searching method. Knowledge base consists of four major parts: rules, data base constants, trip buffer variables and causes. And a user interface is implemented by using menu-driven and window display techniques. The advantage of CASCPCS is that it saves time and effort to diagnose the trip causes of a Core Protection Calculator System, it increases a plant's availability and reliability, and it makes it easy to manage CASCPCS because of using only a cursor control.
