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)

T lymphocytes have been found to harbor P-glycoprotein (Pgp) and to demonstrate modulation of its ion channel transporter function according to the state of activation of T lymphocytes. We hypothesized that cytotoxic chemicals that are extruded by Pgp could be used to specifically eliminate immunoreactive T-cell populations. In this study, we evaluated the capacity of 4,5-dibromorhodamine methyl ester (TH9402), a photosensitizer structurally similar to rhodamine, a dye transported by Pgp, and which becomes highly cytotoxic on activation with visible light to selectively deplete alloreactive T lymphocytes. Stimulation of T cells with mitogens or allogeneic major histocompatibility complex-mismatched cells resulted in the preferential retention of the TH9402 rhodamine-derivative in activated T cells, both CD4+ and CD8+. Photodynamic cell therapy of TH9402-exposed T cells led to the selective elimination of immunoreactive T-cell populations. In addition, this treatment preserved resting T cells and their capacity to respond to third-party cells. Inhibition of Pgp enhanced cellular trapping of the dye in nonactivated T cells and resulted in their depletion after exposure to light. Targeting of Pgp-deficient cells may therefore represent an appealing strategy for the prevention and treatment of graft-versus-host disease and other alloimmune or autoimmune disorders.
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PMID:P-glycoprotein targeting: a unique strategy to selectively eliminate immunoreactive T cells. 1209 25

Posaconazole is a triazole antifungal agent with a spectrum of activity that includes Candida and Cryptococcus species, many molds, and some endemic fungi. Posaconazole has received US Food and Drug Administration approval for the treatment of oropharyngeal candidiasis, including infections refractory to itraconazole and/or fluconazole. It is also approved as prophylaxis for invasive Aspergillus and Candida infections in patients aged >or=13 years who are at high risk of developing these infections, in adult and adolescent hematopoietic stem cell transplant recipients with graft-versus-host disease, and in persons with hematologic malignancies and prolonged neutropenia due to chemotherapy, who are at high risk of developing these infections. Approval for additional indications is being sought. Limited clinical experience suggests efficacy for the treatment of infections due to Zygomycetes and as salvage therapy for patients with invasive aspergillosis and coccidioidomycosis. Currently available only as an oral suspension, posaconazole, which has been well tolerated, requires administration with food or a nutritional supplement to assure adequate bioavailability. Posaconazole is predominantly eliminated in the feces, where it appears as unchanged drug. Metabolism, mostly glucuronidation, plays only a minor role in its elimination, as does renal clearance; as a consequence, dose adjustment is not required in the presence of renal or hepatic insufficiency. Although not a substrate of hepatic CYP450 3A4, posaconazole inhibits this enzyme and thus has the potential for significant pharmacokinetic interactions with drugs metabolized by this isoform. Its use in combination with CYP450 substrates that prolong the QTc interval is contraindicated, as is its use with ergot alkaloids; administration of posaconazole with other substrates and/or inducers of this enzyme system requires caution. Posaconazole is both a substrate and inhibitor of P-glycoprotein. Currently, the major roles for posaconazole in clinical practice are as prophylaxis for neutropenic patients with significant risk of infection with filamentous fungi and as therapy for zygomycoses. It may also have a role in the treatment of other filamentous fungal and some yeast infections, but assessment of its overall place in antifungal therapy awaits the availability of further clinical experience.
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PMID:Reviews of anti-infective agents: posaconazole: a broad-spectrum triazole antifungal agent. 1841 3

Even the most potent immunosuppressive drugs often fail to control graft-versus-host disease (GVHD), the most frequent and deleterious posttransplantation complication. We previously reported that photodepletion using dibromorhodamine (TH9402) eliminates T cells from healthy donors activated against major histocompatibility complex-incompatible cells and spares resting T cells. In the present study, we identified photodepletion conditions selectively eradicating endogenous proliferating T cells from chronic GVHD patients, with the concomittant sparing and expansion of CD4(+)CD25(+) forkhead box protein 3-positive T cells. The regulatory T-cell (Treg) nature and function of these photodepletion-resistant cells was demonstrated in coculture and depletion/repletion experiments. The mechanism by which Tregs escape photodepletion involves active P-glycoprotein-mediated drug efflux. This Treg-inhibitory activity is attributable to interleukin-10 secretion, requires cell-cell contact, and implies binding with cytotoxic T-lymphocyte antigen 4 (CTLA-4). Preventing CTLA-4 ligation abrogated the in vitro generation of Tregs, thus identifying CTLA-4-mediated cell-cell contact as a crucial priming event for Treg function. Moreover, the frequency of circulating Tregs increased in chronic GVHD patients treated with TH9402 photodepleted cells. In conclusion, these results identify a novel approach to both preserve and expand Tregs while selectively eliminating CD4(+) effector T cells. They also uncover effector pathways that could be used advantageously for the treatment of patients with refractory GVHD.
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PMID:Photodepletion differentially affects CD4+ Tregs versus CD4+ effector T cells from patients with chronic graft-versus-host disease. 2112 80

Tacrolimus, a potent immunosuppressant medication, acts by inhibiting calcineurin, which eventually leads to inhibition of T-cell activation. The drug is commonly used to prevent graft rejection in solid organ transplant and graft-versus-host disease in hematopoietic stem cell transplant patients. Tacrolimus has a narrow therapeutic index with variable oral bioavailability and metabolism via cytochrome P-450 3A enzyme. Toxicity can occur from overdosing or from drug-drug interactions with the simultaneous administration of cytochrome P-450 3A inhibitors and possibly P-glycoprotein inhibitors. Tacrolimus toxicity can be severe and may include multiorgan damage. We present a case of suspected tacrolimus toxicity in a postallogeneic hematopoietic stem cell transplant patient who was concurrently using oral marijuana. This case represents an important and growing clinical scenario with the increasing legalization and use of marijuana throughout the United States.
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PMID:High on Cannabis and Calcineurin Inhibitors: A Word of Warning in an Era of Legalized Marijuana. 3025 65