Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.6.3.44 (P-glycoprotein)
 13,344 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

P-glycoprotein (P-gp) expels various drugs from cells, resulting in multidrug resistance, including against glucocorticoids. Here, we present a case of systemic lupus erythematosus (SLE) that suggests the importance of initial intensive treatment in overcoming unresponsiveness due to P-gp overexpression on activated lymphocytes. A 28-year-old woman had been diagnosed with highly active SLE including severe pericarditis, hemolytic anemia, lupus nephritis, and retinopathy. The disease activity of SLE progressed despite 1 mg/kg per day oral prednisolone. At the time, P-gp expression was extremely high, as evaluated by flow cytometric analysis on peripheral lymphocytes. After intensive treatment with three courses of methylprednisolone pulse therapy and plasmapheresis, we succeeded in controlling disease activity in association with marked reduction of P-gp overexpression; namely, the clinical symptoms immediately improved along with the reduction of P-gp expression. These results imply that patients with highly active SLE might have drug unresponsiveness that is mediated by P-gp overexpression on lymphocytes. Therefore, downregulation of P-gp by initial intensive immunosuppressive therapy might be important for overcoming glucocorticoid resistance. We also propose that measurement of P-gp on lymphocytes is a useful test for prediction of drug resistance and may assist in the selection of appropriate initial treatment.
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PMID:Overcoming treatment unresponsiveness mediated by P-glycoprotein overexpression on lymphocytes in refractory active systemic lupus erythematosus. 1702 18

The multi-drug resistance protein -1 or P-glycoprotein-1 ( P-gp1) functions as Energy-dependent efflux pump responsible for decreased drug accumulation in multidrug-resistant cells. Increased P-gp1 expression in lymphocytes of patients with systemic lupus erythematosus (SLE) may influence steroid requirements for disease control. This study evaluates P-gp1 functional activity in CD5+, CD7+ and CD20+ lymphocytes in SLE children and its impact on clinical outcome. 44 SLE children and 50 healthy controls were studied. Estimation of P-gp1 function was based on the efflux of Rhodamine-123 using flow cytometry. Results were expressed as percentage of lymphocytes with high P-gp1 activity. The P-gp1 function in CD5+, CD7+ and CD20+ lymphocytes was significantly higher in patients compared to controls (with P value < 0.05 for each lymphocyte population). The expression of active P-gp1 in CD5+ and CD7+ lymphocytes correlated positively with disease activity as estimated by SLEDAI and ESR. P-gp1 expression in SLE lymphocytes was also found to correlate significantly with some disease manifestations specially lupus nephritis, thrombocytopenia and ANA positivity. Steroids low responders whose SLEDAI were > or = 11 while receiving 1 mg/Kg/day of prednisolone demonstrated higher P-gp1 functions in CD 5+ and CD 7+ lymphocytes compared to high responders whose SLEDAI were < 11 while receiving < 1 mg/Kg/day of prednisolone. CD5+ lymphocyte's P-gp1 function was found to be lower in the patients receiving cyclophosphamide in addition to steroids compared to those on steroids only. It is concluded that measuring P-gp1 function in CD5+ and CD7+ lymphocytes could be one of the prognostic and therapeutic indices in SLE.
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PMID:P-glycoprotein-1 functional activity in CD5+CD7+ and CD20+ lymphocytes in systemic lupus erythematosus children: relation to disease activity, complications and steroid response. 2461 50

True renal lupus vasculitis (TRLV), a vascular lesion usually associated with proliferative lupus nephritis (LN), is resistant to conventional treatments. The expression of P-glycoprotein (P-gp) on activated lymphocytes causes drug resistance. We herein report a patient with TRLV, minimal change LN, overexpression of P-gp on peripheral B cells, and accumulation of P-gp+ B cells at the site of TRLV. High-dose corticosteroids combined with intravenous cyclophosphamide pulse therapy resulted in clinical remission and the long-term normal renal function.
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PMID:Efficacy of Intravenous Cyclophosphamide Pulse Therapy for P-Glycoprotein-expressing B Cell-associated Active True Renal Lupus Vasculitis in Lupus Nephritis. 2862 87

Diffuse proliferative lupus nephritis (DPLN) is a serious organ complication. Drug resistance correlates with P-glycoprotein (P-gp) expression on activated lymphocytes. We encountered a refractory DPLN patient with expansion of peripheral CD69/CXCR3-co-expressing P-gp+CD4+ cells producing IL-2 and IL-6. Treatment with high-dose corticosteroid combined with biweekly intravenous cyclophosphamide pulse therapy (IVCY) failed to reduce the population of activated P-gp+CD4+ cells or control the disease activity. Methotrexate (MTX) with monthly IVCY reduced activated P-gp+CD4+ cells and improved the clinical symptoms, resulting in long-term remission and tapering of corticosteroids. MTX-IVCY combination therapy, which down-regulates the activated P-gp+CD4+ cell-mediated disease activity, may be useful for the treatment of refractory DPLN.
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PMID:Treatment with Methotrexate and Intravenous Cyclophosphamide Pulse Therapy Regulates the P-gp+CD4+ Cell-related Pathogenesis in a Representative Patient with Refractory Proliferative Lupus Nephritis. 3168 86