Modulation of CD39 and Exogenous APT102 Correct Immune Dysfunction in Experimental Colitis and Crohn’s Disease

Abstract

<jats:title>Abstract</jats:title> <jats:sec> <jats:title>Background and Aims</jats:title> <jats:p>CD39/ENTPD1 scavenges pro-inflammatory nucleotides, to ultimately generate immunosuppressive adenosine, which has a central role in immune homeostasis. Global deletion of Cd39 increases susceptibility to experimental colitis while single nucleotide polymorphisms within the human CD39 promoter, and aberrant patterns of expression during experimental hypoxia, predispose to Crohn’s disease. We aimed to define the impact of transgenic human CD39 [hTG] overexpression in experimental colitis and to model therapeutic effects using the recombinant apyrase APT102 in vivo. We also determined the in vitro effects of APT102 on phenotypic and functional properties of regulatory T-lymphocytes derived from patients with Crohn’s disease.</jats:p> </jats:sec> <jats:sec> <jats:title>Methods</jats:title> <jats:p>Colitis was induced by administration of dextran sulfate sodium in wild-type [WT] or hTG mice, and, in another model, by adoptive transfer of CD45RBhigh cells with or without WT or hTG regulatory T cells [Treg]. In additional experiments, mice were treated with APT102. The effects of APT102 on phenotype and function of Treg and type-1 regulatory T [Tr1] cells were also evaluated, after purification from peripheral blood and lamina propria of Crohn’s disease patients [n = 38].</jats:p> </jats:sec> <jats:sec> <jats:title>Results</jats:title> <jats:p>Overexpression of human CD39 attenuated experimental colitis and protected from the deleterious effects of systemic hypoxia, pharmacologically induced by deferoxamine. Administration of APT102 in vivo enhanced the beneficial effects of endogenous Cd39 boosted by the administration of the aryl hydrocarbon receptor [AhR] ligand unconjugated bilirubin [UCB]. Importantly, supplemental APT102 restored responsiveness to AhR stimulation by UCB in Treg and Tr1 cells, obtained from Crohn’s disease patients.</jats:p> </jats:sec> <jats:sec> <jats:title>Conclusions</jats:title> <jats:p>hCD39 overexpression ameliorated experimental colitis and prevented hypoxia-related damage in vivo. Exogenous administration of APT102 boosted AhR-mediated regulatory effects in vivo while enhancing Treg functions in Crohn’s disease in vitro.</jats:p> </jats:sec>

Endogenous antisense RNA curbs CD39 expression in Crohn’s disease

“…CD39 levels and function are decreased in both Treg and Th17 cells derived from the peripheral blood and lamina propria (LP) of Crohn's disease patients 7,8,10 , this being associated with defective Treg function and impaired Th17 cell ability to undergo immunoregulation and subsequent perpetuation of pathogenic potential. Conversely, CD39 overexpression confers Treg increased ability to suppress in a T cell transfer model of colitis 11 .…”

Control of Gut Inflammation by Modulation of Purinergic Signaling

“…Notably, we found that HIF-1α inhibition or ABC transporters blockade obtained upon administration of the antiretroviral ritonavir, limits the detrimental effects of hypoxia in Th17-cells in vitro in in vivo (19). Similarly, administration of the ADPase APT102, restores the response of Treg and Tr1-cells to the regulatory effects of UCB and ameliorates experimental colitis in vivo (20).…”

“…Interestingly, blockade of HIF-1α or ABC transporters limits the detrimental effects of hypoxia both in vitro and in vivo ( 19 ) ( Figure 2C ). Further, human CD39 overexpression or administration of APT102—the extracellular domain with improved ADPase activity of human nucleoside triphosphate diphosphohydrolase-3 (CD39L3), a member of the CD39 family—restores AhR-mediated regulatory effects on CD-derived Tregs in vitro and prevents hypoxia-related damage in experimental colitis in vivo ( 20 ) ( Figure 2D ).…”

Eosinophils and Purinergic Signaling in Health and Disease

“…The following families have been described: ectonucleoside triphosphate diphosphohydrolases (NTPDases), ecto-5′-nucleotidase (CD73), ectonucleotide pyrophosphatase/phosphodiesterases (NPP) and alkaline phosphatases ( 12 ). NTPDases (among which NTPDase1 or CD39) catalyze the conversion of ATP or ADP to AMP and are highly expressed by immune cells and the vasculature ( 46 – 48 ). Extracellular AMP is further hydrolyzed to the anti-inflammatory ADO by CD73 ( 49 , 50 ).…”

“…Accordingly, we recently observed that CD39 overexpression ameliorates experimental colitis and prevents hypoxia-related damage in vivo in a dextran-sulfate-sodium-induced colitis model. In addition, exogenous administration of a recombinant form of human CD39L3 (APT102) boosted the regulatory effects of endogenous CD39 in vivo and enhanced in vitro Treg functions in Crohn's disease ( 48 ). Likewise, the administration of apyrase, which has ectoenzymatic activity comparable to CD39, attenuated peribronchial eosinophilic inflammation and reduced the levels of Th2 cytokines in the bronchoalveolar lavage fluid of mice with allergic airway inflammation ( 52 ).…”