Danazol distribution in plasma and cell membranes as related to altered cell properties: implications for mechanism

Development of human embryonic stem cell-derived cardiomyocytes and application of fluorescence probe substrate for characterization of cytochrome P450 enzyme 2J2

Cardiac cytochrome P450 2J2 (CYP2J2) plays a significant role in cardiovascular homeostasis due to its dual functions in drug metabolism and the epoxidation of polyunsaturated fatty acids. Additionally, the inhibition of CYP2J2 by xenobiotics has been linked to drug-induced cardiotoxicity, warranting further investigation of this critical enzyme in cardiac systems. Human embryonic stem cell-derived cardiomyocytes (hESC-CMs) are physiologically relevant in vitro models that recapitulate relevant phenotypes important for cardiovascular research. However, no studies have so far characterized CYP2J2 expression and activities in these models. Here, we developed and validated H7 hESC-CMs as suitable in vitro models for investigating CYP2J2 in drug metabolism and cardiotoxicity. We first performed the genotyping and confirmed the presence of wild-type CYP2J2∗1/∗1 alleles in wild-type hESCs. Our optimized cardiomyocyte differentiation protocols yielded virtually pure (93.3% ± 6.8%) hESC-CMs, which exhibited P450 epoxygenase mRNA-expression profiles consistent with human cardiomyocytes, with CYP2J2 as the dominant isozyme and minor contributions from CYP2C8 and CYP2C9. By employing a CYP2J2-selective fluorescent substrate, ER-BnXPI, and astemizole as probe substrates, CYP2J2-mediated demethylation of both substrates exhibited typical Michaelis-Menten kinetics, which confirms functional CYP2J2 activities in vitro. Additionally, we demonstrated the capacity of CYP2J2 for arachidonic acid epoxidation, validating its ability to metabolize polyunsaturated fatty acid substrates. Finally, CYP2J2 activity in hESC-CMs was significantly inhibited by danazol and dronedarone, which are established CYP2J2 inhibitors known to cause cardiotoxicity. Ultimately, our study sheds novel insights on hESC-CMs as a suitable model for investigating CYP2J2-mediated metabolism and its inhibition in vitro. SIGNIFICANCE STATEMENT: H7 human embryonic stem cell-derived cardiomyocytes (hESC-CMs) were developed and validated as an in vitro model for investigating CYP2J2-mediated drug metabolism and its inhibition. By characterizing CYP2J2 transcriptional expression, catalytic activity, and inhibition response to established CYP2J2 inhibitors, our study confirmed functional CYP2J2 in hESC-CMs and ascertained that the model recapitulates the physiology of primary cardiomyocytes. This pioneering research highlights the potential of hESC-CMs in advancing our understanding of CYP2J2-mediated metabolism, its inhibition, and implications in drug-induced cardiotoxicity.

Danazol

A comprehensive profile of danazol describing the nomenclatures, formulae, elemental composition, appearance, uses and applications is presented. The profile contains the method which was utilized for the preparation of the drug substance and its respective scheme is outlined. The physical characteristics of the drug including the solubility, X-ray powder diffraction pattern, differential scanning calorimetry, thermal behavior and spectroscopic studies are described. The methods which were used for the analysis of the drug substance in bulk drug and/or in pharmaceutical formulations including the compendial, spectrophotometric, electrochemical and the chromatographic methods are reported. The stability, toxicity, pharmacokinetics, bioavailability, drug evaluation and monitoring, comparisons, pharmacology, in addition to several compiled reviews on the drug substance which were involved. Finally, two hundred and seventy-nine references are listed at the end of this profile.

Comparable Effects of the Androgen Derivatives Danazol, Oxymetholone and Nandrolone on Telomerase Activity in Human Primary Hematopoietic Cells from Patients with Dyskeratosis Congenita

Dyskeratosis congenita (DKC) is a rare inherited disease of impaired telomere maintenance that progressively leads to multi-organ failure, including the bone marrow. By enhancing telomerase activity, androgen derivatives (ADs) are a potential therapeutic option able to re-elongate previously shortened telomeres. Danazol, oxymetholone, and nandrolone are ADs most frequently used to treat DKC. However, no direct in vitro analyses comparing the efficacy of these ADs have been conducted so far. We therefore treated mononuclear cells derived from peripheral blood and bone marrow of four patients with mutations in telomerase reverse transcriptase (TERT, n = 1),in the telomerase RNA component (TERC, n = 2) and in dyskerin pseudouridine synthase 1 (DKC1, n = 1) and found no substantial differences in the activity of these three agents in patients with TERC/TERT mutations. All AD studied produced comparable improvements of proliferation rates as well as degrees of telomere elongation. Increased TERT expression levels were shown with danazol and oxymetholone. The beneficial effects of all ADs on proliferation of bone marrow progenitors could be reversed by tamoxifen, an estrogen antagonist abolishing estrogen receptor-mediated TERT expression, thereby underscoring the involvement of TERT in AD mechanism of action. In conclusion, no significant differences in the ability to functionally enhance telomerase activity could be observed for the three AD studied in vitro. Physicians therefore might choose treatment based on patients’ individual co-morbidities, e.g., pre-existing liver disease and expected side-effects.

Efficacy of Danazol with Autoimmune Thrombocytopenia

Seventy-nine cases of autoimmune thrombocytopenia seen by the Baylor Hematology section of The Methodist Hospital between 1991 and 1996 were retrospectively reviewed to assess the effectiveness of danazol in the treatment of autoimmune thrombocytopenia. Among the 42 patients who received danazol, the mean initial platelet count prior to treatment was 24.3 ± 17.4 (SD) × 109/L with a mean duration of disease of 53 months. Most cases were idiopathic, but some patients had underlying secondary disorders (rheumatoid arthritis, systemic lupus erythematosus, HIV, and/or Evans' syndrome). Overall 57% of the patients treated with danazol had an excellent or a good response with three patients who had unmaintained remission for >11 months. Minimal side effects were noted. Fifty percent of the patients with associated secondary disorders achieved an excellent or good response. The hemolytic component of all three Evans' syndrome cases was well controlled with danazol. In two cases, danazol was effective where a variety of other treatment regimens were not. An excellent or a good response was found in 58%, 62%, and 53% in patients >65 years old, between 45 and 65 years old, and <45 years old, respectively. Response rates were similar in males and females, Seventy percent of the nonsplenectomized patients had an excellent or a good response compared to 33% in postsplenectomy patients. Overall in view of its favorable side-effect profile, it is rational early on to attempt to abrogate the need for splenectomy, it may salvage splenectomy failures, and there is a reasonable response rate in those refractory to multiple prior therapies. Key Words: Autoimmune thrombocytopenia—Idiopathic thrombocytopenic purpura—Danazol— Systemic lupus erythematosus—HIV—Evans' syndrome.

Transendothelial migration of leukocytes is promoted by plasma from a subgroup of immune thrombocytopenic purpura patients with small-vessel ischemic brain disease

We previously described a subgroup of immune thrombocytopenic purpura (ITP) patients presenting with recurring transient ischemic attack-like symptoms and progressive cognitive impairment due to small vessel disease (SVD) seen in the brain. They presented minimal bleeding despite thrombocytopenia, and platelet activation was elevated compared to classic ITP. On the hypothesis that the blood-brain barrier (BBB) is compromised in this subgroup, we investigated the effect of plasma from SVD-ITP patients on the transendothelial migration of leukocytes (TEML). Brain microvascular endothelial cells (BMVEC) were grown to confluence on 6.5-microm pore filters and plasma from 10 healthy controls, 20 classic ITP, and 5 SVD-ITP were added and incubated 24 hr. Then 1 x 10(5) monocytes (U937) were added and the number migrated through the EC monolayer after 6 hr was measured by flow cytometry. The effect on TEML of danazol was also assessed. We found that plasma from SVD-ITP but not classic ITP induced 10-fold rise in EC activation marker CD62E and a sevenfold increase in TEML, to 38.5% +/- 12.5% of cells migrated, compared to normal controls (5.6% +/- 1.2%) or classic ITP (6.1% +/- 0.2%), P < 0.001. Preincubation of U937 with endothelial microparticles (EMP) increased TEML by 20.0% +/- 6.4% with SVD-ITP plasma, significantly more than with classic ITP or control plasmas, P = 0.003. Pretreatment of cultures with danazol (100 microg/mL) inhibited TEML by 25% in all wells tested, whether or not EMP were added. In summary, SVD-ITP plasma activates EC and augments TEML, suggesting plasma-mediated BBB dysfunction in this syndrome. Danazol modestly but significantly inhibited TEML.

Danazol inhibits aromatase activity of endometriosis-derived stromal cells by a competitive mechanism

OBJECTIVE

To evaluate the inhibitory effect of danazol on estrogen (E) production in endometriosis.

DESIGN

Prospective randomized study.

SETTING

Academic research unit of the department of obstetrics and gynecology in a university hospital.

PATIENT(S)

Thirteen patients with endometriosis.

INTERVENTION(S)

Danazol was added to the culture of endometriosis-derived stromal cells or suspensions of microsomes prepared from chocolate cysts.

MAIN OUTCOME MEASURE(S)

The aromatase activities as well as mRNA and protein levels of aromatase in endometriosis-derived stromal cells or microsomes of endometriosis were examined.

RESULT(S)

Danazol treatment with a concentration greater than 10(-6) M significantly suppressed aromatase activity of endometriosis-derived stromal cells under basal and prostaglandin E(2) (PGE(2))-stimulated conditions. Danazol (10(-5) M) did not affect mRNA and protein levels of aromatase. Danazol competitively inhibited aromatase activity (by 1.7 x 10(-6) M of calculated Ki and 2.9 x 10(-5) M of Ki') of endometriosis microsomes.

CONCLUSION(S)

Danazol competitively inhibited aromatase activity in endometriosis-derived stromal cells without affecting either the mRNA or protein levels of aromatase. These results indicate the efficacy of local application of danazol to endometriotic lesions.

Management of immune thrombocytopenic purpura in adults

Primary immune thrombocytopenic purpura (ITP), also referred to as idiopathic thrombocytopenic purpura, is an organ-specific autoimmune disorder in which antibody-coated or immune complex-coated platelets are destroyed prematurely by the reticuloendothelial system, resulting in peripheral blood thrombocytopenia. The disease is heterogeneous with regard to its severity and clinical course and is unpredictable in its response to therapy. Although the basic underlying pathophysiology of ITP has been known for more than 50 years, current treatment guidelines are based on expert opinion rather than on evidence because of a lack of high-quality clinical trials and research. The only patients for whom treatment is clearly required are those with severe bleeding and/or extremely low platelet counts (< 10 x 10(9)/L). Treatment of patients with ITP refractory to corticosteroids and splenectomy requires careful evaluation of disease severity, patient characteristics related to risk of bleeding, and adverse effects associated with treatment. Clinical trials with numerous new agents are under way, which we hope will add more effective and targeted strategies to our therapeutic armamentarium. We describe a logical and structured approach to the clinical management of ITP in adults, based on a literature review and our personal experience.

Idiopathic thrombocytopenic purpura: pathophysiology and management

Our understanding of the pathophysiology of ITP owes to pioneering work of W J Harrington in 1951, delineating the immunologic nature of platelet destruction. In ITP, antibody-coated platelets are destroyed by macrophages of RES. However, other mechanisms are also implicated: C-mediated platelet lysis and newly described C-independent peroxide injury. Both induce platelet fragmentation and lysis, generating procoagulant platelet microparticles (PMP). A third mechanism of platelet consumption in the microvasculature is proposed, based on overlapping syndromes of ITP and TTP in some patients. In assessing hemostasis in ITP, platelet counts alone is not sufficient. Evaluation of platelet clumping, giant platelets, and platelet activation, marked by increased PMP is useful. Patients with platelet activation or giant platelets bleed less and detection of clumping prevents unwarranted therapy. Thrombotic complications may develop in ITP. A syndrome, characterized by recurrent TIA-like symptoms, progressive memory loss due to ischemic small vessel disease is described. The management of ITP should include the search for and elimination of underlying causes and careful evaluation of hemostasis. Therapy is divided into definitive vs symptomatic measures. The former including splenectomy, danazol, chemotherapy offers lasting remission after therapy was stopped, while the later including glucocorticoids, gammaglobuin, antiD antibodies and others increases platelet counts but seldom sustains remission upon withdrawal. Danazol therapy is up-dated since it is an effective and safe definite measure in ITP.

Monitoring of CD59 expression in paroxysmal nocturnal hemoglobinuria treated with danazol

We describe a 52-year-old man with paroxysmal nocturnal hemoglobinuria (PNH) and a moderate transfusion requirement. Prior to and during sequential therapy with androgen (metenolone), glucocorticoid, and danazol, we evaluated CD59-negative expression (PNH clone) in red blood cells, neutrophils, lymphocyte subsets, and bone marrow (BM) CD34(+) cells. Although androgen and glucocorticoid were not effective for recovery of blood cell counts, the hemoglobin and platelet levels increased immediately after the therapy with danazol and the patient became transfusion independent. However, neither the serum level of LDH nor the percentage of PNH clone in each cell lineage, including BM CD34(+) cells, decreased. The number of nucleated cells in BM increased drastically after the start of danazol. These findings suggest that the efficacy of danazol was not only due to the impediment of hemolysis but also due to stimulation of PNH clone proliferation in BM.

Danazol for paroxysmal nocturnal hemoglobinuria

Paroxysmal nocturnal hemoglobinuria (PNH) is a rare clonal stem-cell disorder in which blood cells lack complement inhibiting membrane proteins, and become susceptible to complement-mediated injury, leading to chronic intravascular hemolysis and pancytopenia. Glucocorticoids have been a mainstay of therapy. For patients refractory to glucocorticoids and requiring blood transfusions, an alternative therapy is needed. We studied danazol therapy in 5 patients refractory to other treatments. Four of the 5 benefited, showing rise in hematocrit and eventual cessation of transfusion requirements. Remissions lasted > or =2 years in 3 and 10 years in 1 patient. Danazol was well-tolerated without serious side effects. Danazol appears to be a good alternative treatment in PNH.

Danazol relieves refractory pruritus associated with myeloproliferative disorders and other diseases

Severe pruritus is frequently associated with myeloproliferative and other systemic illnesses, and often fails to respond to conventional measures. We used danazol (Danocrine), a synthetic attenuated androgen, in the treatment of severe pruritus refractory to conventional therapy. Eight patients had myeloproliferative disorders (MPD), seven had autoimmune disorders, and seven had skin diseases. Danazol at 400-800 mg/day was administered, and previous medications were tapered off. When itching was controlled with danazol alone, the dosage was reduced or discontinued, and resumed if itching recurred. Clinical responses were graded, and side effects were monitored. Overall, in 12 of 22 patients refractory to other measures, itching was controlled with danazol alone. In 10 patients itching returned when danazol was discontinued or dosage was continued for up to 5 years in responders. No serious side effects were observed. Our experience indicates that danazol is a good alternative for patients with severe pruritus associated with myeloproliferative and other systemic disorders.