Control of IFN-αA by CD73: Implications for Mucosal Inflammation

Abstract

Inflammatory diseases influence tissue metabolism, altering regulation of extracellular adenine nucleotides, with a resultant protective influence of adenosine. Ecto-5′-nucleotidase (CD73) is a central surface enzyme generating extracellular adenosine. Thus, we hypothesized that CD73 is protective in mucosal inflammation as modeled by trinitrobenzene sulfonate (TNBS) colitis. Initial studies revealed a >3-fold induction of CD73 mRNA levels after TNBS colitis. Additionally, the severity of colitis was increased, as determined by weight loss and colonic shortening, in cd73−/− mice relative to cd73+/+ controls. Likewise, enteral administration of the selective CD73 inhibitor α,β-methylene ADP to cd73+/+ mice resulted in a similar increase in severity of TNBS colitis. Gene array profiling of cytokine mRNA expression, verified by real-time PCR, revealed a >90% down-regulation of IFN-αA in cd73−/− mice and α,β-methylene ADP-treated cd73+/+ mice, compared with cd73+/+ mice. Exogenous administration of recombinant IFN-αA partially protected TNBS-treated cd73−/− mice. Cytokine profiling revealed similar increases in both IFN-γ and TNF-α mRNA in colitic animals, independent of genotype. However, IL-10 mRNA increased in wild-type mice on day 3 after TNBS administration, whereas cd73−/− mice mounted no IL-10 response. This IL-10 response was restored in the cd73−/− mice by exogenous IFN-αA. Further cytokine profiling revealed that this IL-10 induction is preceded by a transient IFN-αA induction on day 2 after TNBS exposure. Together, these studies indicate a critical regulatory role for CD73-modulated IFNαA in the acute inflammatory phase of TNBS colitis, thereby implicating IFN-αA as a protective element of adenosine signaling during mucosal inflammation.

Regulation of adenosine system at the onset of peritonitis

“…Hypoxia, which is common in inflammatory diseases, was shown to induce both CD39 and CD73 mRNA levels and activity [26]. Similarly, in models of colitis [27] and fibrosis [28], CD73 transcript and activity were found to be elevated, and CD39 were shown to significantly increase in both chronic pancreatitis and pancreatic cancer [29].…”

Targeting Hypoxia-Inducible Factor-1 (HIF-1) Signaling in Therapeutics: Implications for the Treatment of Inflammatory Bowel Disease

“…This effect can be mimicked in wild-type mice by pharmacological inhibition of CD73 [112]. Hypoxia-induced up-regulation of CD73 and the resulting increase in the metabolism of AMP to adenosine confers protection to intestinal epithelial cells [112,133]. In culture, epithelial monolayers exposed to hypoxia display a significant increase in trans-epithelial resistance, compared to cells kept at normal oxygen levels.…”

“…During hypoxia or periods of inflammation, CD73 is up-regulated in a HIF-1 -dependent fashion in the intestinal mucosa [13,112]. Targeted deletion of CD73 renders mutant mice significantly more susceptible to experimental models of colitis [133]. This effect can be mimicked in wild-type mice by pharmacological inhibition of CD73 [112].…”

Dietary oils modify the host immune response and colonic tissue damage followingCitrobacter rodentiuminfection in mice

“…Quantitative real-time PCR was performed using the Bio-Rad Laboratories MJ mini Opticon Real-Time PCR System, using IQ SYBR Green Supermix (Bio-Rad). The primer sequences and reaction conditions for ␤-actin, IL -6, IL-10, IL-17A, IL-17F, TNF-␣, IFN-␥, IL-22, IL-23, TGF-␤, FoxP3, monocyte chemoattractant protein 1 (MCP1), keratinocyte cytokine (KC), and macrophage inflammatory protein 2 (MIP2) have been previously described (24,31). Quantification was carried out using Gene Ex Macro OM 3.0 software (Bio-Rad), where PCR efficiencies for each of the primer sets were incorporated into the final calculations.…”