Immunomodulatory assays to study structure-activity relationships of thalidomide

Thalidomide pharmacokinetics in sheep

AIM

To determine the half life (T1/2), time taken to reach maximum plasma concentration (Tmax) and maximum plasma concentration (Cmax) of thalidomide in sheep following I/V, oral and topical treatment with a single dose of thalidomide.

METHOD

Three groups of 4-6-month-old ram lambs were treated with thalidomide dissolved in dimethylsulphoxide (DMSO). The first group (n=10) was treated I/V with 100 mg thalidomide in 2 mL DMSO; the second group (n=8) received 400 mg thalidomide in 2 mL DMSO orally, and the third group (n=8) had 400 mg thalidomide in 4 mL DMSO applied topically. Plasma samples were collected up to 36 hours after treatment, snap-frozen at -80°C and analysed for concentrations of thalidomide using high performance liquid chromatography.

RESULTS

Following I/V administration, T1/2 was 5.0 (SEM 0.4) hours, volume of distribution was 3,372.0 (SEM 244.3) mL/kg and clearance was 487.1 (SEM 46.1) mL/hour.kg. Topical application of 400 mg thalidomide did not increase plasma concentrations. Following oral administration, thalidomide bioavailability was 89%, with T1/2, Tmax, and Cmax being 7.2 (SEM 0.8) hours, 3.0 (SEM 0.4) hours and 1,767.3 (SEM 178.1) ng/mL, respectively.

CONCLUSION

Topical administration using DMSO as a solvent did not increase concentrations of thalidomide in plasma. The mean pharmacokinetic parameters determined following oral treatment with 400 mg of thalidomide were similar to those reported in humans receiving a single 400 mg oral dose (T1/2 7.3 hours; Tmax 4.3 hours and Cmax 2,820 ng/mL). There is potential for thalidomide to be used as a model for the treatment of chronic inflammatory conditions in sheep, such as Johne's disease, where tumour necrosis factor alpha plays a pathogenic role.

Treatment of severe non-infectious uveitis in high-risk conditions (Part 2): systemic infections; management and safety issues

INTRODUCTION

Management of patients with severe immune-mediated uveitis requires the use of immunosuppressive (IS) drugs in selected cases. This may be particularly challenging in certain patients with associated conditions, which may increase the risk of side effects or modify guidelines for the use of such drugs. Chronic viral and mycobacterial infections in the setting of non-infectious uveitis create a number of diagnostic but also therapeutic dilemmas to clinicians because they can be exacerbated by IS therapies with detrimental effects.

AREAS COVERED

In this review, we will focus on very specific chronic infections that can be affected by IS therapies: human immunodeficiency virus infection, chronic hepatitis virus infection and tuberculosis. The main aim of this review is to provide an updated and comprehensive practical guide for practitioners regarding the therapeutic decision-making and management of patients with non-infectious uveitis affected by the aforementioned infectious conditions.

EXPERT OPINION

Clinicians should be aware of the risk of viral and mycobacterial reactivation of an underlying infection during IS therapy. However, most of these conditions do not represent an absolute contraindication if one were able to apply an appropriate prior screening and close monitoring of such therapy.

Identification of a promising PI3K inhibitor for the treatment of multiple myeloma through the structural optimization

BACKGROUND

We previously reported a PI3K inhibitor S14161 which displays a promising preclinical activity against multiple myeloma (MM) and leukemia, but the chiral structure and poor solubility prevent its further application.

METHODS

Six S14161 analogs were designed based on the structure-activity relationship; activity of the compounds in terms of cell death and inhibition of PI3K were analyzed by flow cytometry and Western blotting, respectively; anti-myeloma activity in vivo was performed on two independent xenograft models.

RESULTS

Among the six analogs, BENC-511 was one of the most potent compounds which significantly inhibited PI3K activity and induced MM cell apoptosis. BENC-511 was able to inactivate PI3K and its downstream signals AKT, mTOR, p70S6K, and 4E-BP1 at 1 μM but had no effects on their total protein expression. Consistent with its effects on PI3K activity, BENC-511 induced MM cell apoptosis which was evidenced by the cleavage of Caspase-3 and PARP. Notably, addition of insulin-like growth factor 1 and interleukin-6, two important triggers for PI3K activation in MM cells, partly blocked BENC-511-induced MM cell death, which further demonstrated that PI3K signaling pathway was critical for the anti-myeloma activity of BENC-511. Moreover, BENC-511 also showed potent oral activity against myeloma in vivo. Oral administration of BENC-511 decreased tumor growth up to 80% within 3 weeks in two independent MM xenograft models at a dose of 50 mg/kg body weight, but presented minimal toxicity. Suppression of BENC-511 on MM tumor growth was associated with decreased PI3K/AKT activity and increased cell apoptosis.

CONCLUSIONS

Because of its potent anti-MM activity, low toxicity (LD50 oral >1.5 g/kg), and easy synthesis, BENC-511 could be developed as a promising agent for the treatment of MM via suppressing the PI3K/AKT signaling pathway.

Effect of thalidomide and arsenic trioxide on the release of tumor necrosis factor-α and vascular endothelial growth factor from the KG-1a human acute myelogenous leukemia cell line

Studies conducted in our lab have indicated that thalidomide cytotoxicity in the KG-1a human acute myelogenous leukemia (AML) cell line was enhanced by combining it with arsenic trioxide. The current investigation was conducted in order to evaluate the effect of thalidomide either alone or in combination with arsenic trioxide on the release of tumor necrosis factor-α (TNF-α) and vascular endothelial growth factor (VEGF) from this cell line in an attempt to clarify its possible cytotoxic mechanism(s). Human AML cell line KG-1a was used in this study. The cells were cultured for 48 h in the presence or absence of thalidomide (5 mg/l), and or arsenic trioxide (4 μM). The levels of TNF-α and VEGF in the supernatant were determined by ELISA. Results obtained indicate that the levels of TNF-α in the supernatant of KG-1a cell cultures incubated with thalidomide, arsenic trioxide, or combination were statistically lower than those observed in the supernatant of control cells (2.89, 5.07, 4.15 and 16.88 pg/ml, respectively). However, the levels of VEGF in the supernatant of thalidomide-treated cells were statistically higher than those in the supernatant of control cells (69.61 vs. 11.48 pg/l). Arsenic trioxide, whether alone or in combination with thalidomide, did not produce any statistically significant difference in the levels of VEGF as compared to the control or thalidomide-treated cell supernatant. These findings indicate that thalidomide and the arsenic trioxide inhibition of TNF-α production by KG-1a cells may play an important role in their cytotoxic effect.

The immunosuppressant drug, thalidomide, improves hepatic alterations induced by a high-fat diet in mice

BACKGROUND

Pro-inflammatory cytokines, such as tumour necrosis factor (TNF)-alpha, are known to be involved in the establishment of insulin resistance. Insulin resistance plays a key role in the development of obesity-related pathologies, such as type 2 diabetes and non-alcoholic fatty liver disease (NAFLD). The state of chronic inflammation associated with obesity led us to hypothesize that TNF-alpha blockade may have an effect on experimentally obese animals.

AIMS

We studied the effects of thalidomide, an immunosuppressant and anti-TNF-alpha drug, on hepatic alterations that were induced by a high-fat diet (HFD) in mice.

METHODS

Obesity was induced in Swiss mice using a HFD for 12 weeks. Thalidomide-treated animals received thalidomide i.p. (100 mg/kg/day, 10 days). Glucose, aspartate aminotransferases and alanine aminotransferases levels were assessed in the blood. Insulin and glucose tolerance tests were performed. The liver was excised for histological, triglyceride, gene and protein expression analyses.

RESULTS

We found improvements in both the basal glucose blood levels and the response to insulin administration in the treated animals. The molecular analysis of insulin signalling revealed a restoration of the hepatic insulin receptor substrate (IRS)-1 and AKT phosphorylation. The hepatic expression of TNF-alpha was inhibited and the levels correlated with a significant reduction in the steatosis area. Other hepatic inflammatory markers, such as iNOS and suppressor of cytokine signalling (SOCS-3), were also reduced.

CONCLUSIONS

We suggest that immunosuppressant drugs that target TNF-alpha and that may also contribute to reductions in the inflammatory markers that are associated with obesity could be a therapeutic option in NAFLD and type 2 diabetes.

Use of etanercept in human immunodeficiency virus (HIV) and acquired immunodeficiency syndrome (AIDS) patients

BACKGROUND

Etanercept (Enbrel, Amgen, Thousand Oaks, CA), a soluble p75 tumor necrosis factor receptor:FC (TNFR:FC) fusion protein for plasma cytokines, specifically tumor necrosis factor-alpha (TNF-alpha), is used in the treatment of immune-mediated rheumatic diseases. To our knowledge, the use of etanercept in patients with human immunodeficiency virus (HIV) and acquired immunodeficiency syndrome (AIDS) is relatively uncommon.

OBJECTIVE

The main purpose of this short review is to examine the safety of etanercept in patients with HIV/AIDS.

METHODS

A Medline search was conducted using the keywords etanercept and HIV and/or AIDS for any published articles between 1966 to the present (September 2004).

RESULTS

A case report, one case series, and one clinical trial pertained to the use of etanercept in HIV patients. No reports were found on the use of etanercept in AIDS. In addition, two case reports were found documenting the use of infliximab in HIV patients.

DISCUSSION

Preliminary reports indicate that the administration of etanercept does not appear to increase the morbidity or mortality rates in HIV. The inhibition of TNF-alpha may actually improve the symptoms of HIV/AIDS-associated aphthous ulcers, cachexia, dementia, fatigue, and fever, as well as help manage concomitant rheumatic diseases and psoriasis.

CONCLUSION

The use of etanercept shows promise for applications in disease management in patients with HIV/AIDS. Continued research efforts are necessary to establish the long-term safety and efficacy of etanercept and other biologic agents in this patient population.

Modulation of cytokine production by some phthalimido-desmuramyl dipeptides and their cytotoxicity

Muramyl dipeptide (MDP) is the smallest bacterial cell wall peptidoglycan component having immunomodulatory activity. In an attempt to obtain MDP derivatives with improved and better defined pharmacological profiles we synthesized a new lipophilic phthalimido-desmuramyl dipeptide, LK 508. This novel MDP analogue and three structurally related phthalimido-desmuramyl dipeptides (LK 413, LK 511 and LK 512) were evaluated immunologically. Their ability to modulate the production of cytokines was measured in vitro by their inclusion in cultures of human peripheral blood mononuclear cells (PBMC) activated by ionomycin and phorbol-12-myristate-13-acetate (PMA). The results were compared with the analogous activity of MDP. All compounds tested are strong up-regulators of IL-12 synthesis. All compounds except LK 512 also stimulated IFNgamma synthesis. LK 508, LK 511 and LK 512 are effective in up-regulating IL-2 production. LK 508 and LK 512 considerably up-regulate the synthesis of IL-4 and IL-10. LK 413 and MDP stimulated the production of Th1 promoting and Th1 (IFNgamma and IL-12) cytokines, while LK 508, LK 511 and LK 512 non-selectively up-regulated the production of both Th1 and Th2-types of (IL-4 and IL-10) cytokines. None of the phthalimido-desmuramyl dipeptides was cytotoxic in vitro against the normal cell line HUVEC (human endothelial cells) thereby indicating their potential for use in vivo.

Management of erythema nodosum leprosum by thalidomide: thalidomide analogues inhibit M. leprae-induced TNFalpha production in vitro

Thalidomide is being successfully used for the treatment of erythema nodosum leprosum (ENL), among other disorders with inflammatory and immunological bases. Although the active molecules responsible for the diverse therapeutic activities of the drug and the sequence of reactions triggered inside the cells remain unclear, it was demonstrated that thalidomide (THAL) inhibits TNFalpha mRNA expression and protein production by stimulated monocytes and activated T lymphocytes. Patients treated with THAL experienced a reduction in serum TNFalpha levels and it diminished cytokine gene expression at the lesion site, with a concomitant abrogation of clinical symptoms. It has been reported that thalidomide as well as some its analogues decrease M. leprae-induced TNFalpha and IL-12 mRNA in vitro. THAL also reduced monocyte apoptosis in the cultures. The present data further support thalidomide's effects on TNFa synthesis and the growing need to search for new specific TNFalpha inhibitors (non-teratogenic compounds) that might be potentially used in clinical disorders such as leprosy.

Theoretical basis for the activity of thalidomide

The revival of thalidomide began shortly after the drug was withdrawn from the market because of its teratogenic properties. Therapeutic effects of thalidomide were found accidentally in leprosy patients with erythema nodosum leprosum (ENL). Subsequent research widened the understanding of the activity of thalidomide, and with improved methodology and the augmented background knowledge of immunology it was possible to interpret the properties of thalidomide more coherently. Effects on tumour necrosis factor-alpha (TNFalpha) release play an important role in the ability of thalidomide to affect the immune system. Alteration of synthesis and release of cytokines such as interleukin (IL)-1, IL-2, IL-4, IL-6, IL-8, IL-10, IL-12 and interferon-gamma is involved in the complex mechanisms of thalidomide. Thalidomide targets leucocytes, endothelial cells and keratinocytes, affecting them in a different manner and at different cellular levels. Changes in the density of adhesion molecules alter leucocyte extravasation and the inflammatory response in the tissue involved. Several mechanisms for the teratogenic action of thalidomide are currently under review, but this mode of action of the drug still remains unclear and we review evidence-based hypotheses for the teratogenicity of thalidomide. Thalidomide shows significant clinical impact in several diseases such as ENL in lepromatous leprosy, chronic graft-versus-host disease, systemic lupus erythematosus, sarcoidosis, aphthous lesions in HIV infection, wasting syndrome in chronic illness, inflammatory bowel disease, multiple myeloma and some solid tumours. In 1998 the US Food and Drug Administration approved thalidomide exclusively for the treatment of ENL, and strict conditions were stipulated for its use in order to prevent teratogenic adverse effects. However, despite the promising findings of thalidomide at the molecular level, namely its anti-TNFalpha properties and its intercalation with DNA, and activity in clinical trials, there is still a great need for more intensive research.

In vitro antiinflammatory effects of neolignan woorenosides from the rhizomes of Coptis japonica

Five dihydrobenzofuran neolignans, woorenosides I (1), II (2), III (3), IV (4), and V (5), isolated from Coptis japonica (Ranunculaceae), suppressed tumor necrosis factor (TNF)-alpha and nitric oxide (NuOmicron) production, as well as lymphocyte proliferation triggered by inflammatory signals such as various mitogens, in a dose-dependent manner. The results indicate that the woorenosides strongly inhibit the mitogenic response by activated macrophage and lymphocytes and suggest that these compounds may participate in regulating inflammatory processes.

Thalidomide stimulates splenic IgM antibody response and cytotoxic T lymphocyte activity and alters leukocyte subpopulation numbers in female B6C3F1 mice

Thalidomide has been shown to have antiinflammatory and, more recently, immunomodulating properties, which are beneficial for the treatment of an ever-increasing list of immune related diseases. Although considerable knowledge regarding thalidomide s antiinflammatory properties has been acquired, relatively little is known about its immunomodulating properties in vivo. In this paper, a panel of immune assays was used to evaluate immunomodulation in female B6C3F1 mice treated intraperitoneally for 28 days with thalidomide (30, 100, or 150 mg/kg/day). Spleen antibody forming cell response was significantly enhanced by 37% in mice treated with 150 mg/kg/day, despite an 8% decrease in the percentage of Ig+ B cells. A significant stimulatory trend was observed for the cytotoxic T cell response across thalidomide treatment groups. An evaluation of the spleen leukocyte subpopulations revealed a 23% increase in the absolute number of CD8+ T cells in the 150 mg/kg treatment group and a 9 and 11% decrease in the absolute number of NK cells in both the 100 and 150 mg/kg thalidomide treatment groups, respectively. These findings demonstrate that, in addition to modulating spleen leukocyte numbers, thalidomide also stimulates murine humoral and cellular immune responses in vivo.

Frequent good partial remissions from thalidomide including best response ever in patients with advanced refractory and relapsed myeloma

Twenty-three patients with advanced and heavily pretreated myeloma were treated with thalidomide. Starting dose was 200 mg/d, and 20 patients had dose escalations up to 400 (n = 5), 600 (n = 12) or 800 mg/d (n = 3), usually in divided doses. Nineteen patients were refractory to recent chemotherapy, and four had untreated relapse after prior intensive therapy. Ten out of 23 patients (43%) achieved partial response (PR; nine with refractory and one with relapsed disease), six patients had minor response or stabilization of the disease and four had disease progression. Another three patients died early from advanced myeloma at less than 3 weeks of thalidomide therapy. Of the 10 patients with PR, seven had a better response than after any prior therapy, despite vincristine-doxorubicin-dexamethasone (VAD)-based treatment in all but one and high-dose melphalan with autologous stem cell support in four. Time to achieve PR was rapid in patients receiving thalidomide in divided doses (median 31 d). Responses also included reduced bone marrow plasma cell infiltration and improved general status. Normalized polyclonal gammaglobulin levels were seen in four cases. Six out of 10 patients with PR remained in remission with a median time on treatment of 23 weeks (range 15-50 weeks). Sedation was common but usually tolerable, and some patients continued full- or part-time work. Four patients had skin problems, three patients had pneumonia, one hypothyrosis, one sinus bradycardia and one minor sensory neuropathy. Thalidomide may induce good partial remissions in advanced refractory myeloma with tolerable toxicity, and should be evaluated in other settings for myeloma patients. Divided thalidomide doses seem to reduce time to achieve remission and may improve response rate.

Immunomodulatory effect of arctigenin, a lignan compound, on tumour necrosis factor-alpha and nitric oxide production, and lymphocyte proliferation

We have investigated the immunomodulatory effects of arctigenin, a dibenzyl butyrolactone lignan compound, on tumour necrosis factor (TNF)-alpha and nitric oxide (NO) production, and lymphocyte proliferation. Arctigenin inhibited strongly TNF-alpha production by lipopolysaccharide-stimulated murine macrophage RAW264.7 and differentiated human macrophage U937 with IC50 values of 5.0 and 3.9 microM, respectively, without displaying cytotoxicity. The TNF-alpha inhibitory effect of arctigenin in lipopolysaccharide-triggered RAW264.7 cells was increased by co-treatment with several known TNF-alpha inhibitors. It also potently attenuated T and B cell proliferation stimulated by concanavalin A and lipopolysaccharide in a dose-dependent manner with IC50 values of 2.9 and 14.6 microM, respectively. In contrast, the compound showed a different pattern in lipopolysaccharide- and interferon (IFN)-gamma-induced NO production from RAW264.7 cells. Arctigenin inhibited NO release by IFN-gamma signal, whereas it significantly enhanced lipopolysaccharide-triggered NO production in RAW264.7 cells. The results suggested that arctigenin may regulate immune responses in activated macrophages and lymphocytes including TNF-alpha and NO production and lymphocyte proliferation.

Eudesmin inhibits tumor necrosis factor-alpha production and T cell proliferation

Possible antiinflammatory effects of eudesmin were examined by assessing the effects on tumor necrosis factor (TNF)-alpha production and lymphocyte proliferation as well as cytotoxicity against murine and human macrophages. The compound significantly inhibited TNF-alpha production by lipopolysaccharide (LPS)-stimulated murine macrophage RAW264.7 without displaying cytotoxicity suggesting that eudesmin may inhibit TNF-alpha production without any interference of normal cell function. It also significantly attenuated T cell proliferation stimulated by concanavalin A (Con A) in a dose-dependent manner.

Thalidomide responsiveness in an infant with Behçet's syndrome

BACKGROUND

Behçet's syndrome is a chronic relapsing vasculitis characterized by aphthous stomatitis, genital ulcerations, and uveitis. The disease is a multisystem illness, which may involve the skin, joints, gastrointestinal tract, blood vessels, central nervous system, and other organs.

CASE STUDY

We report a case of an infant with features of Behçet's syndrome who did not respond to conventional immunosuppression with high-dose corticosteroids and cytotoxic agents. Thalidomide, a potent immune response-modifying drug, was used with marked improvement and resolution of symptoms.

CONCLUSION

This finding supports a trial of thalidomide treatment in patients with Behçet's syndrome who are unresponsive to other forms of immunosuppressive therapy or develop undesirable side effects.