Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0018133 (graft-versus-host disease)
 18,032 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Purine nucleoside analogues are a new class of drugs with activity against non-dividing lymphocytes. They should thus play a major role in the treatment of low grade lymphoid malignancies. These drugs have been shown to have strong effect in DNA synthesis on actively dividing cells, mainly through interference with DNA polymerases and ribonucleotide reductase. However, the cell cycle kinetics of low grade lymphocytic lymphomas is characterized by the presence of very low growth fractions. Hence, the action of these drugs in slowly progressing lymphoid malignancies cannot be accounted by the same mechanism observed in actively proliferating tumors and needs to be explained through activity against quiescent resting lymphocytes. Recent work has stressed the role of purine analogues in inducing programmed cell death of quiescent lymphocytes, which could be explained through the induction of accelerated DNA strand breaks. This process leads to consumption of NAD for poly(ADP-ribose) synthesis, which could induce critical depletion of ATP. As this action extends to normal resting lymphocytes deleterious effects related to their immunosuppressive action are also observed, i.e. prolonged lymphopenia predominating in T cells and especially in CD4 subset, increased frequency of opportunistic infections and perhaps increase in autoimmune complications like autoimmune hemolytic anemia. Nevertheless, beneficial effects of this immunosuppressive action have also been reported in the prevention of graft-versus-host disease, graft rejection and in some autoimmune diseases like multiple sclerosis. Work needs to be carried out to define better the mechanisms of action of these drugs on the different immunological effectors, as well as studies in animal models of transplantation and autoimmune diseases.
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PMID:Adverse and beneficial immunological effects of purine nucleoside analogues. 913 60

Acute graft-versus-host disease (aGVHD) and tumor relapse remain major complications after allogeneic hematopoietic stem cell transplantation. Alloreactive T cells and cancer cells share a similar metabolic phenotype to meet the bioenergetic demands necessary for cellular proliferation and effector functions. Nicotinamide adenine dinucleotide (NAD) is an essential co-factor in energy metabolism and is constantly replenished by nicotinamide phosphoribosyl-transferase (Nampt), the rate-limiting enzyme in the NAD salvage pathway. Here we show, that Nampt blockage strongly ameliorates aGVHD and limits leukemic expansion. Nampt was highly elevated in serum of patients with gastrointestinal GVHD and was particularly abundant in human and mouse intestinal T cells. Therapeutic application of the Nampt small-molecule inhibitor, Fk866, strongly attenuated experimental GVHD and caused NAD depletion in T-cell subsets, which displayed differential susceptibility to NAD shortage. Fk866 robustly inhibited expansion of alloreactive but not memory T cells and promoted FoxP3-mediated lineage stability in regulatory T cells. Furthermore, Fk866 strongly reduced the tumor burden in mouse leukemia and graft-versus-leukemia models. Ex vivo studies using lymphocytes from GVHD patients demonstrated potent antiproliferative properties of Fk866, suggesting potential clinical utility. Thus, targeting NAD immunometabolism represents a novel approach to selectively inhibit alloreactive T cells during aGVHD with additional antileukemic efficacy.
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PMID:Targeting NAD immunometabolism limits severe graft-versus-host disease and has potent antileukemic activity. 3197 33