Nicotinamide adenine dinucleotide (NAD) and its metabolites inhibit T lymphocyte proliferation: role of cell surface NAD glycohydrolase and pyrophosphatase activities.
The presence of NAD-metabolizing enzymes (e.g., ADP-ribosyltransferase (ART)2) on the surface of immune cells suggests a potential immunomodulatory activity for ecto-NAD or its metabolites at sites of inflammation and cell lysis where extracellular levels of NAD may be high. In vitro, NAD inhibits mitogen-stimulated rat T cell proliferation. To investigate the mechanism of inhibition, the effects of NAD and its metabolites on T cell proliferation were studied using ART2a+ and ART2b+ rat T cells. NAD and ADP-ribose, but not nicotinamide, inhibited proliferation of mitogen-activated T cells independent of ART2 allele-specific expression. Inhibition by P2 purinergic receptor agonists was comparable to that induced by NAD and ADP-ribose; these compounds were more potent than P1 agonists. Analysis of the NAD-metabolizing activity of intact rat T cells demonstrated that ADP-ribose was the predominant metabolite, consistent with the presence of cell surface NAD glycohydrolase (NADase) activities. Treatment of T cells with phosphatidylinositol-specific phospholipase C removed much of the NADase activity, consistent with at least one NADase having a GPI anchor; ART2- T cell subsets contained NADase activity that was not releasable by phosphatidylinositol-specific phospholipase C treatment. Formation of AMP from NAD and ADP-ribose also occurred, a result of cell surface pyrophosphatase activity. Because AMP and its metabolite, adenosine, were less inhibitory to rat T cell proliferation than was NAD or ADP-ribose, pyrophosphatases may serve a regulatory role in modifying the inhibitory effect of ecto-NAD on T cell activation. These data suggest that T cells express multiple NAD and adenine nucleotide-metabolizing activities that together modulate immune function.
Bortell
R
R
Diabetes Division, Department of Medicine, University of Massachusetts Medical School, Worcester, MA 01655, USA. rita.bortell@umassmed.edu
Moss
J
J
McKenna
R C
RC
Rigby
M R
MR
Niedzwiecki
D
D
Stevens
L A
LA
Patton
W A
WA
Mordes
J P
JP
Greiner
D L
DL
Rossini
A A
AA
D036002:ADP Ribose Transferases; D000241:Adenosine / Q000378:metabolism / Q000494:pharmacology; D000244:Adenosine Diphosphate / Q000378:metabolism / Q000494:pharmacology; D000246:Adenosine Diphosphate Ribose / Q000378:metabolism / Q000494:pharmacology; D000249:Adenosine Monophosphate / Q000378:metabolism / Q000494:pharmacology; D000818:Animals; D000945:Antigens, Differentiation, T-Lymphocyte; D002462:Cell Membrane / Q000201:enzymology / Q000276:immunology / Q000378:metabolism; D002478:Cells, Cultured; D002772:Cholera Toxin / Q000494:pharmacology; D005260:Female; D006649:Histocompatibility Antigens / Q000096:biosynthesis; D007166:Immunosuppressive Agents / Q000378:metabolism* / Q000494:pharmacology*; D008213:Lymphocyte Activation / Q000187:drug effects; D008297:Male; D008562:Membrane Glycoproteins; D008934:Mitogens / Q000494:pharmacology; D009243:NAD / Q000378:metabolism / Q000502:physiology*; D009244:NAD+ Nucleosidase / Q000378:metabolism* / Q000502:physiology; D037342:Pertussis Toxin; D043265:Phosphatidylinositol Diacylglycerol-Lyase; D054801:Phosphoinositide Phospholipase C; D010761:Phosphorus Radioisotopes / Q000378:metabolism; D011065:Poly(ADP-ribose) Polymerases / Q000096:biosynthesis; D011755:Pyrophosphatases / Q000378:metabolism* / Q000502:physiology; D051381:Rats; D011913:Rats, Inbred BB; D011920:Rats, Inbred WF; D013601:T-Lymphocytes / Q000187:drug effects / Q000201:enzymology* / Q000276:immunology* / Q000378:metabolism; D010738:Type C Phospholipases / Q000494:pharmacology; D010566:Virulence Factors, Bordetella / Q000494:pharmacology
D000945:Antigens, Differentiation, T-Lymphocyte; D006649:Histocompatibility Antigens; D007166:Immunosuppressive Agents; D008562:Membrane Glycoproteins; D008934:Mitogens; D010761:Phosphorus Radioisotopes; D010566:Virulence Factors, Bordetella; D009243:NAD; D000246:Adenosine Diphosphate Ribose; D000249:Adenosine Monophosphate; D000244:Adenosine Diphosphate; D002772:Cholera Toxin; D036002:ADP Ribose Transferases; D011065:Poly(ADP-ribose) Polymerases; C090163:Art2b protein, rat; D037342:Pertussis Toxin; D010738:Type C Phospholipases; D054801:Phosphoinositide Phospholipase C; D009244:NAD+ Nucleosidase; D011755:Pyrophosphatases; C024289:NAD pyrophosphatase; D043265:Phosphatidylinositol Diacylglycerol-Lyase; D000241:Adenosine