Mechanism of action and resistance to glucocorticoid and selective glucocorticoid receptor modulator to overcome glucocorticoid-related adverse effects

Methylprednisolone aceponate for atopic dermatitis

BACKGROUND

The 4th generation topical corticosteroids (TCS) have demonstrated a most favorablerisk-benefit ratio. Methylprednisolone aceponate (MPA) is a non-halogenated corticosteroid with a methyl group at C6, which confers higher intrinsic activity. MPA is included in the group of potent TCS (category III/IV).

METHODS

A literature review is carried out of the clinical efficacy, pharmacokinetics, and adverse effects of MPA, especially for the treatment of atopic dermatitis (AD).

RESULTS

Several clinical studies support the use of MPA in infants and children, with minimal local or systemic adverse effects reported. The pharmacokinetic profile and the low rate of adverse effects of MPA are most suitable for the treatment of atopic dermatitis (AD), a chronic disease with frequent flaring that can involve extensive areas of the skin.

CONCLUSIONS

Most patients with AD can be easily brought into control with the use of only TCS. Achieving a complete healing of eczema is key in AD, and once the skin is clinically healthy, emollients can be used according to the physician and patient preferences. Physicians should be trained in the recognition of early or subtle manifestations of active eczema that are most suitably treated with topical TCS to achieve a most rapid and satisfactory control of the disease. If the whole area with eczema is not treated, active eczema will remain and treatment will be ineffective. Insufficient use of TCS will lead to inefficiency and frustration.

The dominant negative β isoform of the glucocorticoid receptor is uniquely expressed in erythroid cells expanded from polycythemia vera patients

Glucocorticoid receptor (GR) agonists increase erythropoiesis in vivo and in vitro. To clarify the effect of the dominant negative GRβ isoform (unable to bind STAT-5) on erythropoiesis, erythroblast (EB) expansion cultures of mononuclear cells from 18 healthy (nondiseased) donors (NDs) and 16 patients with polycythemia vera (PV) were studied. GRβ was expressed in all PV EBs but only in EBs from 1 ND. The A3669G polymorphism, which stabilizes GRβ mRNA, had greater frequency in PV (55%; n = 22; P = .0028) and myelofibrosis (35%; n = 20) patients than in NDs (9%; n = 22) or patients with essential thrombocythemia (6%; n = 15). Dexamethasone stimulation of ND cultures increased the number of immature EBs characterized by low GATA1 and β-globin expression, but PV cultures generated great numbers of immature EBs with low levels of GATA1 and β-globin irrespective of dexamethasone stimulation. In ND EBs, STAT-5 was not phosphorylated after dexamethasone and erythropoietin treatment and did not form transcriptionally active complexes with GRα, whereas in PV EBs, STAT-5 was constitutively phosphorylated, but the formation of GR/STAT-5 complexes was prevented by expression of GRβ. These data indicate that GRβ expression and the presence of A3669G likely contribute to development of erythrocytosis in PV and provide a potential target for identification of novel therapeutic agents.