Evidence that SMS 201-995 enhances the immunosuppressive effect of FK506

Octreotide for the treatment of systemic lupus erythematosus: clinical effects and an in vitro study on its therapeutic mechanism

Increased serum growth hormone (GH), together with high expression of growth hormone receptor on peripheral blood mononuclear cells (PBMCs), correlates with systemic lupus erythematosus (SLE) activity, suggesting that modulation of GH signaling may affect SLE activity. We explored the effects of octreotide (OCT), an analog of somatostatin that suppresses the release of GH, in SLE. The objectives of the study were to investigate effects of OCT on the proliferative capacity and cytokine expression of PBMCs from patients with SLE and to investigate therapeutic effects of OCT in patients with SLE. PBMCs from 13 active/inactive SLE patients and 11 controls were pretreated with or without GH and cultured with OCT. The proliferation of PBMCs was assessed by MTT assay and cytokines were quantified by ELISA. We compared the clinical response of 12 patients with SLE treated with OCT (100 µg twice daily) with 12 patients treated with prednisone over three months. OCT inhibited PBMC proliferation in a dose-dependent manner and decreased the secretion of interleukin-6 (IL-6), interleukin-10 (IL-10), and interferon-gamma (IFN-γ). Patients treated with OCT demonstrated improvements in SLEDAI, dsDNA titer, complement levels, and erythrocyte sedimentation rate (ESR). OCT inhibited PBMC proliferation and PBMC secretion of IL-6, IL-10 and IFN-γ stimulated by GH. Treatment of patients with OCT resulted in clinical improvement in SLE.

Tacrolimus: 10 years of successful clinical application

Tacrolimus (FK506) is the first drug from the new class of drugs - calcineurin inhibitors. It has a great potential and can change the current approaches to treatment of different dermatoses. Topical forms of Tacrolimus are activated due to the effect on T-lymphocyte signal transduction, and they also inhibit gene transcription. As a result, the T-cell response to antigens is alleviated. Percutaneous absorption of Tacrolimus in affection foci is higher than in healthy skin. Due to this a smaller amount of the drug is absorbed by the skin as long as the skin is healed. Systemic absorption of Tacrolimus is low in the course of treatment. The maximum clinical experience has been gained in the field of applying Tacrolimus for treatment of atopic dermatitis. In a number of clinical studies, 0.03-0.3% Tacrolimus ointment efficiently reduced the severity of symptoms and course of atopic dermatitis in adults and children. Moreover, topical treatment with Tacrolimus did not involve any substantial toxic effects. The patients most often complained of local irritations in the area where the ointment was applied, which were transient by nature and did not demand the drug withdrawal. Today Tacrolimus is a valuable and safer alternative to glucocorticosteroids for treatment of atopic dermatitis. It can also be used for treating other dermatoses, which demands additional all-round examination.

Inhibitory effect of pasireotide and octreotide on lymphocyte activation

Somatostatin (SST) regulates the function of the central and peripheral nervous system, the endocrine and exocrine organs, as well as the vascular and immune system. These actions are mediated by five specific membrane somatostatin receptors. This study compares the effects on human lymphocytes of two long-acting somatostatin analogues that have different receptor affinity: octreotide and pasireotide. Both analogues have an antiproliferative effect on human lymphocyte proliferation, but they act at different concentration and, while octreotide enhances IL10 and inhibits gamma IFN pasireotide inhibits IL2 and gamma IFN. In both sets of experiment the different behaviour of the two analogues could be due to their different affinity to the SSTR subtypes. Finally this study suggest that the growth inhibitory action of somatostatin analogues is an apoptotic phenomenon and it can be mediated by SSTR2a, in the case of octreotide, and by SSTR3 when pasireotide is used or it can be mediated by the heterodimerization of the two receptor.

The apoptotic effect of somatostatin analogue SMS 201-995 on human lymphocytes

The antiproliferative effect of a synthetic octapeptide, somatostatin analogue SMS 201-995 (SMS), and its capacity to bind were evaluated on human peripheral blood lymphocytes (PBL) activated by phytohemoagglutinin (PHA). We then addressed our work to investigate if SMS inhibits PHA activation of PBL by a cytostatic rather than a cytotoxic mechanism. Consequently, we studied the cell cycle distribution and the activation of caspase-3, measuring the presence of the cleavage product of poly(ADP-ribose) polymerases (PARP), and we evaluated the presence of apoptotic DNA by using a monoclonal antibody specific for the single-stranded regions of DNA. All our results indicate that SMS induces apoptosis in activated lymphocytes.

Antiangiogenic effects of somatostatin analogues

Inhibition of angiogenesis has become a target for antineoplastic therapy and for treatment of retinal neovascularization. The presence of somatostatin receptors on tumour cells and on the proliferating vascular endothelium has led to several in vitro and in vivo studies to investigate the antiproliferative and antiangiogenic effects of somatostatin analogues. Currently available data suggest that somatostatin analogues might inhibit angiogenesis directly through somatostatin receptors present on endothelial cells and also indirectly through the inhibition of growth factor secretion such as IGF-I and vascular endothelial growth factor (VEGF) and reducing monocyte chemotaxis. However, beneficial effects on inhibition of neovascularization have been questioned by some studies. More work is therefore required to firmly establish the role of somatostatin analogues as potential antiangiogenic therapy. The currently available somatostatin analogues have high affinity for somatostatin receptor subtype 2 (sst2) and, to a lesser extent, sst5 and sst3. However, because vascular endothelial cells express several types of somatostatin receptors, it will be important to investigate somatostatin analogues with different receptor subtype affinities, which might increase the spectrum of available therapy for tumours.

Tacrolimus: a review of its use for the management of dermatoses

The newly developed immunomodulator tacrolimus (FK506) is the first of a new class of agents that have enormous potential to change the way that dermatoses are treated and managed. Tacrolimus has been found to be active in a topical formulation with the latter exerting its effects by acting on the signal transduction pathways inside T cells and inhibiting gene transcription. The result is decreased responsiveness of T cells to antigens. Percutaneous absorption of tacrolimus is higher in diseased skin as opposed to healthy skin and, therefore, the drug will be taken in at progressively lower quantities as lesions heal. There is limited systemic absorption of tacrolimus over the course of therapy. The most extensive experience with tacrolimus has been in treating atopic dermatitis. In numerous trials, tacrolimus ointment 0.03-0.3% has shown to be effective in reducing the symptoms and severity of atopic dermatitis in adults and the paediatric population. Furthermore, there have been no significant toxic effects associated with topical therapy with tacrolimus. The most common complaint is that of local irritation after applying the ointment. This is generally transient and the patient is able to continue with therapy. The other dermatoses where tacrolimus has been used include contact dermatitis, psoriasis and pyoderma gangrenosum.