A1 and A2A adenosine receptors play a protective role to reduce
prevalence of autoimmunity following tissue damage
Abstract
Tissue damage associated with trauma might release a sufficient
autoantigen substrate to break immune tolerance. In a previous study, we
showed that the leukopenia observed following severe inflammation is
related to adenosine A1-receptor (A1R) desensitization and A2AR
upregulation. We hypothesized that, under destructive pathological
conditions this mechanism is beneficial in reducing prevalence of
autoimmunity. In this study, we aim to evaluate the protective role of
A1R and A2AR in prevention of autoimmune diseases. We used two murine
models of autoimmune diseases: type 1 diabetes (T1D) induced by low-dose
streptozotocin and pristane-induced lupus (PIL) and on neutrophils we
studied NETosis regulation by adenosine. In both the T1D and PIL models,
A1R-KO mice were predisposed to the development of autoimmunity. In the
PIL model, in WT mice, parallel to the decline of A1R mRNA levels,
lymphocytes number dropped (-85%) 6h after pristane injection. WT mice
remained without any sign of disease at 36 weeks. In contrast, following
pristane 43% of A1R-KO mice suffered from lupus-like disease. Compared
to A1R-KO, in WT mice at 10 days A2AR mRNA levels were significantly
higher. Similar to PIL, in T1D model the presence of A1R and A2AR was
protective. In addition, we found that A1R increases and A2AR suppresses
NETosis. We suggest that adenosine-dependent immune suppression and
reduction in neutrophil extracellular traps (NETs) limits the reactive
T-cells and development of anti-double strand DNA (dsDNA) antibodies
that promote autoimmunity.