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

Machine learning analysis of the relationship between changes in immunological parameters and changes in resistance to Listeria monocytogenes: a new approach for risk assessment and systems immunology

No method has been reported to predict, even approximately, the impact of mild-to-moderate changes in several immunological parameters on resistance to infection. The ability to make such predictions would be useful in risk assessment. In addition, equations that predict host resistance on the basis of changes in components of a complex biological system (the immune system) would fulfill one of the major goals of systems biology. In this study, multiple machine learning classification methods were used to predict the effects of a series of drugs and chemicals on host resistance to Listeria monocytogenes in mice on the basis of changes in several holistic immunological parameters. A data set produced under the sponsorship of the National Toxicology Program (NTP) was used in this study. The NTP data set was found to have a high percentage of missing data and to be noisy (probably due to the intrinsically stochastic nature of immune responses). Data preprocessing steps were used to mitigate these problems. In evaluating the machine learning classifiers, we first randomly partitioned the NTP data set into 10 subsets. Each time, we used nine subsets of the data to train the machine learning classifiers, and the remaining single subset to predict outcomes with regard to host resistance. This process was repeated until all 10 combinations of the 9-1 split of the subsets have been tested. The best of the classifiers predicted host resistance outcome correctly for 94.7% of cases, a result which indicates it is possible to identify mathematical expressions that will be useful for risk assessment and to establish a basis for systems immunology.

The ratio between CD4 + and CD8 + cells in the peripheral blood of patients with hematological malignancies is not altered by thalidomide

Thalidomide is thought to have anti-angiogenic and immunomodulatory properties, including suppression of tumor necrosis factor-alpha, effects on interleukins and interferons, down-regulation of some cell adhesion molecules, and changes in the proportion of lymphocyte subsets. It is unclear whether the clinical response to thalidomide in patients with multiple myeloma (MM), idiopathic myelofibrosis (IM), and myelodysplastic syndromes (MDS) is related to its ability to inhibit angiogenesis or its immunomodulatory effects. We examined the effect of thalidomide on T-lymphocyte subsets in 18 patients with MDS, 6 patients with MM, 4 patients with IM, and 3 patients with angioimmunoblastic lymphoma (AILD). These patients had either a relapse or progressive disease following cytotoxic chemotherapy including high-dose chemotherapy with autologous stem cell support. Thalidomide was first administered at 100 mg/day p.o. and increased to 400 mg/day. T-lymphocyte subsets (CD4+, CD8+) were measured by fluorescence-activated cell sorter (FACS) before and during treatment with thalidomide. Twenty-six of 31 patients responded to thalidomide, most of them achieving partial remission. The median concentration of CD4+ cells was 443/microl, the median of CD8+ cells was 359/microl (CD3 992/microl). In our cohort, no significant changes in absolute numbers or proportions of CD3+ (P = 0.12), CD4+ (P = 0.668), or CD8+ (P = 0.143) cells were observed following the treatment with thalidomide. Although the CD4/CD8 ratio declined from 1.6 to 1.0 during 3 months of thalidomide treatment, this had no statistical significance (P = 0.1). Our findings show that an effect of thalidomide on the T lymphocytes studied is unlikely to be of major importance for the clinical effects.

Thalidomide: mechanisms of action

The classification of thalidomide as an orphan drug with anti-inflammatory actions has led to its off-label use in conditions refractory to other medications. Although the observed clinical effects of thalidomide suggest it to have immunomodulatory capabilities, the mechanism of action is unclear. Here we review both the positive and negative studies of thalidomide at the bench in order to improve our understanding of the possible mechanisms of this drug in treating a variety of diseases at the bedside. Studies on the effects of thalidomide on the innate and adaptive immune system as well as tumorigenesis and angiogenesis are discussed.

Immune parameters in multiple myeloma patients: influence of treatment and correlation with opportunistic infections

The present study evaluated cellular and humoral immune parameters in myeloma patients, focusing on the effect of treatment and the risk of opportunistic infections. Peripheral blood lymphocyte subsets and serum levels of nonmyeloma immunoglobulins (Ig) were analysed in 480 blood samples from 77 myeloma patients. Untreated myeloma patients exhibited significantly reduced CD4+/45RO+, CD19+, CD3+/HLA-DR+, and natural killer (NK) cells, as well as nonmyeloma IgA, IgG and IgM. Conventional-dose chemotherapy resulted in significantly reduced CD4+ and even further decline of CD4+/CD45RO+ and CD19+ cells, most notably in relapsed patients. Additional thalidomide treatment had no significant effects on these parameters. Following high-dose chemotherapy (HD-CTX), prolonged immunosuppression was observed. Although CD8+, NK, CD19+ and CD+/CD45RO+ cells recovered to normal values within 60, 90, 360 and 720 days, respectively, CD4+ counts remained reduced even thereafter. Nine opportunistic infections were observed, including five cytomegalovirus (CMV) diseases, one Pneumocystis carinii pneumonia (PCP) and three varicella zoster virus infections with CMV diseases and PCP occurring exclusively after HD-CTX. Opportunistic infections were correlated with severely reduced CD4+, as well as CD4+/CD45RO+ and CD19+ counts. Thus, myeloma patients display cellular and humoral immunodeficiencies, which increase following conventional as well as HD-CTX, and constitute an important predisposing factor for opportunistic infections.

Differential surface expression of CD18 and CD44 by neutrophils in bone marrow and spleen contributed to the neutrophilia in thalidomide-treated female B6C3F1 mice

Previously, we have reported that thalidomide (Thd) can enhance neutrophil function in female B6C3F1 mice. The present study was intended to evaluate the mechanisms underlying the enhanced neutrophil responses following Thd treatment intraperitoneally (100 mg/kg) for 14 or 28 days. Treatment with Thd increased the numbers of neutrophils in the spleen, peripheral blood, bone marrow, peritoneal cavity and lungs of female B6C3F1 mice when compared to the vehicle control mice. Thd treatment for 14 days increased the percentage and the number of neutrophils in the spleen in the first 8 h (peaking at 2 h) after the last Thd treatment, and it returned to the baseline after 24 h. However, Thd treatment for 28 days increased the percentage and number of neutrophils in the spleen even at the 24-h time point after the last Thd treatment. These neutrophils were demonstrated to be functional by the myeloperoxidase activity assay. Further studies have ruled out the possibility of an increased bone marrow granulopoiesis following Thd treatment. Flow cytometric analysis of the surface expression of adhesion molecules suggested that Thd treatment for either 14 or 28 days decreased the surface expression of either CD18 or CD44 by bone marrow neutrophils. On the other hand, the surface expression of both CD18 and CD44 by splenic neutrophils was increased following Thd treatment for 28 days but not for 14 days. No effect was produced for other cell surface molecules such as CD62L and CD11a. It was possible that decreased surface expressions of CD18 and CD44 facilitated neutrophils' release from the bone marrow; increased surface expressions of CD44 and CD18 by splenic neutrophils after 28 days of Thd treatment increased their ability to remain in the periphery. Taken together, Thd treatment increased neutrophils in female B6C3F1 mice, at least partially, through differentially modulating the surface expression of CD18 and CD44 by the neutrophils in the bone marrow and spleen.

Effects of combined therapy with thalidomide and glucantime on leishmaniasis induced by Leishmania major in BALB/c mice

For treating Leishmania major infection in BALB/c mice, we used thalidomide in conjunction with glucantime. Groups of mice were challenged with 510(3) metacyclic promastigotes of L. major subcutaneously. A week after the challenge, drug treatment was started and continued for 12 days. Thalidomide was orally administrated 30 mg/kg/day and glucantime was administrated intraperitoneally (200 mg/kg/day). It was shown that the combined therapy is more effective than single therapies with each one of the drugs since the foot pad swelling in the group of mice received thalidomide and glucantime was significantly decreased (0.9 +/- 0.2 mm) compared to mice treated with either glucantime, thalidomide, or carrier alone (1.2 +/- 0.25, 1.4 +/- 0.3, and 1.7 +/- 0.27 mm, respectively). Cytokine study showed that the effect of thalidomide was not dependent on IL-12; however, it up-regulated IFN-gamma and down-regulated IL-10 production. Conclusively, thalidomide seems promising as a conjunctive therapy with antimony in murine model of visceral leishmaniasis.

Transport of thalidomide by the human intestinal caco-2 monolayers

Studies in patients have indicated that the oral absorption of thalidomide is considerably variable at high doses (>200 mg/day). The aim of this study was to investigate the transport of racemic thalidomide using human colon cancer cell line (Caco-2) monolayers, which have been widely used to investigate drug permeability. A typical 21-day protocol was used to prepare Caco-2 monolayers. Thalidomide was determined by a validated high performance liquid chromatography method with ultraviolet detection. The integrity of Caco-2 monolayer was confirmed when the transepithelial electrical resistance (TEER) exceeded 300 Ohmz . cm2, and the leakage of 14C-manitol was <1% per hour. Uptake of thalidomide by Caco-2 cells was very limited (up to 2.1%). The transport of thalidomide appeared to be linear up to 1 hr. Our study indicated that the permeability coefficients (Papp) of thalidomide at 2.5-300 microM from the apical (AP) to basolateral (BL) and from BL to AP side was 2-6 x 10(-5) cm/sec, with a marked decrease in Papp values from AP to BL at increased thalidomide concentration. The transport of thalidomide was sodium-, temperature- and pH-dependent, as replacement of extracellular sodium chloride or reducing temperature and apical pH can result in significant decreases in the Papp values. Additional data indicated that transport of thalidomide is energy-dependent, as it was significantly (P < 0.05) inhibited by the ATP inhibitors, sodium azide and 2,4-dinitrophenol. In addition, DL-glutamic acid, cytidine, diprodomole, papaverine, quinidine, and cyclophosphamide significantly (P < 0.05) inhibited the transport of thalidomide, while the P-glycoprotein inhibitor verapamil and other nucleosides and nucleotides such as thymidine and guanine had no effect. These results indicated that thalidomide was rapidly transported by Caco-2 monolayers, and this might involve a saturable energy-dependent transporter.

Thalidomide: dermatological indications, mechanisms of action and side-effects

Thalidomide was first introduced in the 1950s as a sedative but was quickly removed from the market after it was linked to cases of severe birth defects. However, it has since made a remarkable comeback for the U.S. Food and Drug Administration-approved use in the treatment of erythema nodosum leprosum. Further, it has shown its effectiveness in unresponsive dermatological conditions such as actinic prurigo, adult Langerhans cell histiocytosis, aphthous stomatitis, Behçet's syndrome, graft-versus-host disease, cutaneous sarcoidosis, erythema multiforme, Jessner-Kanof lymphocytic infiltration of the skin, Kaposi sarcoma, lichen planus, lupus erythematosus, melanoma, prurigo nodularis, pyoderma gangrenosum and uraemic pruritus. This article reviews the history, pharmacology, mechanism of action, clinical uses and adverse effects of thalidomide.

Drug bioactivation, covalent binding to target proteins and toxicity relevance

A number of therapeutic drugs with different structures and mechanisms of action have been reported to undergo metabolic activation by Phase I or Phase II drug-metabolizing enzymes. The bioactivation gives rise to reactive metabolites/intermediates, which readily confer covalent binding to various target proteins by nucleophilic substitution and/or Schiff's base mechanism. These drugs include analgesics (e.g., acetaminophen), antibacterial agents (e.g., sulfonamides and macrolide antibiotics), anticancer drugs (e.g., irinotecan), antiepileptic drugs (e.g., carbamazepine), anti-HIV agents (e.g., ritonavir), antipsychotics (e.g., clozapine), cardiovascular drugs (e.g., procainamide and hydralazine), immunosupressants (e.g., cyclosporine A), inhalational anesthetics (e.g., halothane), nonsteroidal anti-inflammatory drugs (NSAIDSs) (e.g., diclofenac), and steroids and their receptor modulators (e.g., estrogens and tamoxifen). Some herbal and dietary constituents are also bioactivated to reactive metabolites capable of binding covalently and inactivating cytochrome P450s (CYPs). A number of important target proteins of drugs have been identified by mass spectrometric techniques and proteomic approaches. The covalent binding and formation of drug-protein adducts are generally considered to be related to drug toxicity, and selective protein covalent binding by drug metabolites may lead to selective organ toxicity. However, the mechanisms involved in the protein adduct-induced toxicity are largely undefined, although it has been suggested that drug-protein adducts may cause toxicity either through impairing physiological functions of the modified proteins or through immune-mediated mechanisms. In addition, mechanism-based inhibition of CYPs may result in toxic drug-drug interactions. The clinical consequences of drug bioactivation and covalent binding to proteins are unpredictable, depending on many factors that are associated with the administered drugs and patients. Further studies using proteomic and genomic approaches with high throughput capacity are needed to identify the protein targets of reactive drug metabolites, and to elucidate the structure-activity relationships of drug's covalent binding to proteins and their clinical outcomes.

Extended histopathology in immunotoxicity testing: interlaboratory validation studies

There has been considerable interest in the use of expanded histopathology as a primary screen for immunotoxicity assessment. To determine the utility of a semiquantitative histopathology approach for examining specific structural and architectural changes in lymphoid tissues, a validation effort was initiated. This study addresses the interlaboratory reproducibility of extended histopathology, using tissues from studies of ten test chemicals and both negative and positive controls from the National Toxicology Program's immunotoxicology testing program. We examined the consistency between experienced toxicologic pathologists, who had varied expertise in immunohistopathology in identifying lesions in immune tissues, and in the sensitivity of the individual and combined histopathological endpoints to detect chemical effects and dose response. Factor analysis was used to estimate the association of each pathologist with a so-called "common factor" and analysis-of-variance methods were used to evaluate biases. Agreement between pathologists was highest in the thymus, in particular, when evaluating cortical cellularity of the thymus; good in spleen follicular cellularity and in spleen and lymph node-germinal center development; and poorest in spleen red-pulp changes. In addition, the ability to identify histopathological change in lymphoid tissues was dependent upon the experience/training that the individual pathologist possessed in examining lymphoid tissue and the apparent severity of the specific lesion.

Thalidomide inhibits UVB-induced mouse keratinocyte apoptosis by both TNF-α-dependent and TNF-α-independent pathways

BACKGROUND

Thalidomide is an anti-inflammatory pharmacologic agent that has been utilized as a therapy for a number of dermatologic diseases. Its anti-inflammatory properties have been attributed to its ability to antagonize tumor necrosis factor-alfa (TNF-alpha) production by monocytes. However, its mechanism of action in the skin is not known.

PURPOSE

To test our hypothesis that thalidomide may antagonize TNF-alpha production in the skin, we used a mouse model for acute ultraviolet-B (UVB) exposure, a known stimulus for inducing this cytokine.

RESULTS

A single bolus dose of thalidomide (either 100 or 400 mg/kg) given immediately before UVB exposure (40-120 mJ/cm2) inhibited, in a dose-dependent manner, sunburn cell formation (i.e. keratinocyte (KC) apoptosis as defined by histologic appearance and confirmed by terminal transferase mediated biotinylated dUTP nick end labelling staining) in mouse skin biopsy specimens. However, this agent did not affect the formation of cyclobutane pyrimidine dimers, a measure of UVB-induced DNA damage, which is an early event associated with apoptosis. RNase protection assays confirmed that high (400 mg/kg), but not low (100 mg/kg), doses of thalidomide inhibited the UVB-induced increase in steady-state TNF-alpha mRNA. Additionally, our in vitro data using neonatal mouse KCs showed that thalidomide prevented UVB-induced cell death (JAM assay). The antiapoptotic effects of thalidomide can be reversed by the addition of exogenous recombinant mouse TNF-alpha and hence reconstituting UVB-induced programmed cell death. The inhibition of sunburn cell formation by low-dose thalidomide in the absence of TNF-alpha inhibition suggests that other, unidentified mechanisms of apoptosis inhibition are active.

CONCLUSIONS

These data suggest that the anti-inflammatory effects of thalidomide can affect UVB injury, and may, in part, explain its action in photosensitivity diseases such as cutaneous lupus erythematosus.

Species differences in the structure and function of the immune system

With the recent publication of regulatory guidelines from both the FDA and the CPMP addressing the investigation of immunotoxicity of new chemical entities has come the requisite increased application of immunotoxicology protocols. Importantly, the fulfillment of these protocols may require the use of different species, and while in many cases information concerning the structure and function of the immune system can be readily translated across species, there are numerous and significant species differences that need to be considered. In some cases, the generation of meaningful immunotoxicology data can be adversely affected by the choice of a species that does not adequately share the immune function of concern with man. Likewise immunotoxicology testing in one species may produce negative data in one species but positive data in another. Knowing the mechanistic basis through an understanding of species differences in the structure and function of the immune system is pivotal to success. This becomes especially true as pharmaceutical companies design and develop highly specific immunomodulatory molecules that demonstrate species-specific pharmacology. This review is an exploration of various species differences in the structure and function of the immune system and an attempt to identify those differences that may be important in the conduct of immunotoxicity tests.

Thalidomide in cancer treatment: a potential role in the elderly?

There is increased interest in the treatment of cancer with thalidomide because of its antiangiogenic, immunomodulating and sedative effects. In animal models, the antitumour activity of thalidomide is dependent on the species, route of administration and coadministration of other drugs. For example, thalidomide has shown antitumour effects as a single agent in rabbits, but not in mice. In addition, the antitumour effects of the conventional cytotoxic drug cyclophosphamide and the tumour necrosis factor inducer 5,6-dimethylxanthenone-4-acetic acid (DMXAA) were found to be potentiated by thalidomide in mice bearing colon 38 adenocarcinoma tumours. Further studies have revealed that thalidomide upregulates intratumoral production of tumour necrosis factor-alpha 10-fold over that induced by DMXAA alone. Coadministration of thalidomide also significantly reduced the plasma clearance of DMXAA and cyclophosphamide. All these effects of thalidomide may contribute to the enhanced antitumour activity. Recent clinical trials of thalidomide have indicated that it has minimal anticancer activity for most patients with solid tumours when used as a single agent, although it was well tolerated. However, improved responses have been reported in patients with multiple myeloma. Palliative effects of thalidomide on cancer-related symptoms have also been observed, especially for geriatric patients with prostate cancer. Thalidomide also eliminates the dose-limiting gastrointestinal toxic effects of irinotecan. There is preliminary evidence indicating that the clearance of thalidomide may be reduced in the elderly. The exact role of thalidomide in the treatment of cancer and cancer cachexia in the elderly remains to be elucidated. However, it may have some value as part of a multimodality anticancer therapy, rather than as a single agent.

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.