ABSTRACT
The P2X(7) receptor (P2X(7)R) is an ATP-gated ion channel expressed by monocytes and macrophages. To directly address the role of this receptor in interleukin (IL)-1 beta post-translational processing, we have generated a P2X(7)R-deficient mouse line. P2X(7)R(-/-) macrophages respond to lipopolysaccharide and produce levels of cyclooxygenase-2 and pro-IL-1 beta comparable with those generated by wild-type cells. In response to ATP, however, pro-IL-1 beta produced by the P2X(7)R(-/-) cells is not externalized or activated by caspase-1. Nigericin, an alternate secretion stimulus, promotes release of 17-kDa IL-1 beta from P2X(7)R(-/-) macrophages. In response to in vivo lipopolysaccharide injection, both wild-type and P2X(7)R(-/-) animals display increases in peritoneal lavage IL-6 levels but no detectable IL-1. Subsequent ATP injection to wild-type animals promotes an increase in IL-1, which in turn leads to additional IL-6 production; similar increases did not occur in ATP-treated, LPS-primed P2X(7)R(-/-) animals. Absence of the P2X(7)R thus leads to an inability of peritoneal macrophages to release IL-1 in response to ATP. As a result of the IL-1 deficiency, in vivo cytokine signaling cascades are impaired in P2X(7)R-deficient animals. Together these results demonstrate that P2X(7)R activation can provide a signal that leads to maturation and release of IL-1 beta and initiation of a cytokine cascade.
Subject(s)
Gene Deletion , Interleukin-1/biosynthesis , Protein Precursors/biosynthesis , Receptors, Purinergic P2/deficiency , Receptors, Purinergic P2/physiology , Adenosine Triphosphate/pharmacology , Animals , Cells, Cultured , Cyclooxygenase 2 , Enzyme Induction/drug effects , Fluorescent Dyes/metabolism , Gene Targeting , Inflammation/genetics , Interleukin-1/metabolism , Interleukin-6/biosynthesis , Interleukin-6/metabolism , Isoenzymes/metabolism , Lipopolysaccharides/pharmacology , Macrophages, Peritoneal/drug effects , Macrophages, Peritoneal/metabolism , Mice , Mice, Knockout , Nigericin/pharmacology , Prostaglandin-Endoperoxide Synthases/metabolism , Protein Precursors/metabolism , Protein Processing, Post-Translational/drug effects , Purinergic P2 Receptor Agonists , Receptors, Purinergic P2/genetics , Receptors, Purinergic P2X7ABSTRACT
Cathepsins have been implicated in the degradation of proteins destined for the MHC class II processing pathway and in the proteolytic removal of invariant chain (Ii), a critical regulator of MHC class II function. Mice lacking the lysosomal cysteine proteinase cathepsin S (catS) demonstrated a profound inhibition of Ii degradation in professional APC in vivo. A marked variation in the generation of MHC class II-bound Ii fragments and presentation of exogenous proteins was observed between B cells, dendritic cells, and macrophages lacking catS. CatS-deficient mice showed diminished susceptibility to collagen-induced arthritis, suggesting a potential therapeutic target for regulation of immune responsiveness.
Subject(s)
Antigen Presentation , Antigens, Differentiation, B-Lymphocyte/metabolism , Arthritis/immunology , Cathepsins/physiology , Histocompatibility Antigens Class II/metabolism , Animals , Arthritis/chemically induced , Cathepsins/genetics , Collagen , Dendritic Cells/immunology , Dendritic Cells/metabolism , Drug Design , Gene Targeting , Macrophages/immunology , Macrophages/metabolism , Mice , Mice, Knockout , Spleen/immunology , Spleen/metabolismABSTRACT
The authors provide the results of long-term investigations of the consequences of environmental pollution from the military nuclear plant in the Southern Urals. Altogether 28,100 individuals who received substantial doses of external and internal radiation in the Techa riverside in the early fifties were entered into the study. The increase in the leukemia incidence as compared with unexposed controls has been confirmed on a statistical basis. The majority of excess cases of leukemia were recorded within the 5th to the 20th year after irradiation and may be attributed to the acute and chronic granulocytic types. The level of leukemia risk on the basis of the Techa river data is evaluated as 0.48-1.10 per 10(4) persons/years/Gy.
