Effect of thalidomide on apoptosis of lymphocytes and neutrophils

The role of polymorphonuclear neutrophils during HIV-1 infection

It is well-recognized that human immunodeficiency virus type-1 (HIV-1) mainly targets CD4⁺ T cells and macrophages. Nonetheless, during the past three decades, a huge number of studies have reported that HIV-1 can directly or indirectly target other cellular components of the immune system including CD8⁺ T cells, B cells, dendritic cells, natural killer cells, and polymorphonuclear neutrophils (PMNs), among others. PMNs are the most abundant leukocytes in the human circulation, and are known to play principal roles in the elimination of invading pathogens, regulating different immune responses, healing of injured tissues, and maintaining mucosal homeostasis. Until recently, little was known about the impact of HIV-1 infection on PMNs as well as the impact of PMNs on HIV-1 disease progression. This is because early studies focused on neutropenia and recurrent microbial infections, particularly, during advanced disease. However, recent studies have extended the investigation area to cover new aspects of the interactions between HIV-1 and PMNs. This review aims to summarize these advances and address the impact of HIV-1 infection on PMNs as well as the impact of PMNs on HIV-1 disease progression to better understand the pathophysiology of HIV-1 infection.

Thalidomide plus chemotherapy exhibit enhanced efficacy in the clinical treatment of T-cell non-Hodgkin's lymphoma: A prospective study of 46 cases

The treatment of T-cell non-Hodgkin's lymphoma (T-NHL) remains challenging. There is currently no standard regimen for the treatment of T-NHL in the first- or second-line setting. Thalidomide was previously shown to exert antitumor effects through inhibiting angiogenesis, promoting apoptosis and immunomodulatory activity. However, all the previous studies on the treatment of lymphoma with thalidomide included patient samples of limited size. In the present study, 46 cases of eligible T-NHL patients were randomized into i) the control group (conventional combined chemotherapy, n=22) and ii) the thalidomide group (thalidomide plus combined chemotherapy, n=24). The median dose of thalidomide was 200 mg (range, 150-400 mg) every night, without reported severe side effects. The clinical response to treatment was as follows: Complete response (CR) in 12 cases, partial response (PR) in 7, stable disease (SD) in 1 and progressive disease (PD) in 4 cases in the thalidomide group; and CR in 8 cases, PR in 6, SD in 3 and PD in 5 cases in the control group. The CR rate was 50.0 and 36.4% in the thalidomide and the control groups, respectively (P<0.05). The median progression-free and overall survival were 12 and undefined months, respectively, in the thalidomide group and 6 and 17 months, respectively, in the control group. The toxicity profile was considered acceptable in both groups. Our results indicated that thalidomide plus combined chemotherapy may exhibit enhanced efficacy in the clinical treatment of T-NHL. In addition, this type of treatment may reduce the frequency of adverse gastrointestinal reactions and help alleviate fear of chemotherapy. Therefore, thalidomide plus combined chemotherapy may be a viable option for the clinical treatment of T-NHL.

Thalidomide has anti-inflammatory properties in neonatal immune cells

Neonates demonstrate functional immaturity and dysregulation of immune responses leading to systemic inflammation and enhanced apoptosis of immune cells. Thalidomide has already been proven to differentially regulate immune responses and support anti-apoptosis in immunodeficiency syndromes. Thus, it was the aim of this study to evaluate the effects of thalidomide on the cytokine response and apoptosis of neonatal immune cells. After whole blood culture and stimulation of cord and adult blood samples, the intracytoplasmic expression and the secreted amounts of IL-2, TNF-α, IFN-γ, IL-6, IL-10 and IL-8 were assessed by flow cytometry and Cytokine Bead Array. Apoptosis was detected using Annexin-V staining. Bcl-2 expression was analysed using the Cytokine Bead Array Apoptosis Kit. Exposure to thalidomide (100 µg/ml) reduced the intracytoplasmic pro-inflammatory cytokine production of neonatal monocytes and the IFN-γ production of neonatal lymphocytes. In supernatants, the addition of thalidomide resulted in reduction of TNF-α, IL-6, IL-10 and, by trend, IFN-γ. While stimulated neonatal lymphocytes exhibited susceptibility to apoptosis, thalidomide tended to diminish apoptotic cells. Bcl-2 expression tended to be increased after addition of thalidomide. The potent anti-inflammatory effects of thalidomide and its anti-apoptotic properties in cord blood immune cells provide the basis for future strategies to optimise treatment of neonatal infections and immunodeficiency syndromes.

The continuing challenges of leprosy

Leprosy is best understood as two conjoined diseases. The first is a chronic mycobacterial infection that elicits an extraordinary range of cellular immune responses in humans. The second is a peripheral neuropathy that is initiated by the infection and the accompanying immunological events. The infection is curable but not preventable, and leprosy remains a major global health problem, especially in the developing world, publicity to the contrary notwithstanding. Mycobacterium leprae remains noncultivable, and for over a century leprosy has presented major challenges in the fields of microbiology, pathology, immunology, and genetics; it continues to do so today. This review focuses on recent advances in our understanding of M. leprae and the host response to it, especially concerning molecular identification of M. leprae, knowledge of its genome, transcriptome, and proteome, its mechanisms of microbial resistance, and recognition of strains by variable-number tandem repeat analysis. Advances in experimental models include studies in gene knockout mice and the development of molecular techniques to explore the armadillo model. In clinical studies, notable progress has been made concerning the immunology and immunopathology of leprosy, the genetics of human resistance, mechanisms of nerve injury, and chemotherapy. In nearly all of these areas, however, leprosy remains poorly understood compared to other major bacterial diseases.

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.

Thalidomide can costimulate or suppress CD4+ cells' ability to incorporate [H3]-thymidine--dependence on the primary stimulant

Thalidomide is a drug that can enhance mitogen- and antigen-stimulated cells' ability to synthesize IL-2. To assess if thalidomide could concomitantly enhance the synthesis of IFN-gamma and incorporation of [H3]-thymidine, peripheral blood mononuclear cells (PBMC) were incubated in the presence or absence of thalidomide and staphylococcal enterotoxin A (SEA), anti-CD3, Con-A or PHA. After 18 h, the cultures were sampled for IL-2. At the termination of the 3-day cultures, they were assayed for IFN-gamma and incorporation of [H3]-thymidine. Regardless of the mitogen used to stimulate the PBMC, the thalidomide-treated PBMC produced more IL-2 than controls. Thalidomide enhanced IFN-gamma synthesis in the Con-A and anti-CD3-stimulated PBMC. It suppressed the ability of SEA and PHA-stimulated PBMC to incorporate [H3]-thymidine, whereas it enhanced incorporation of [H3]-thymidine in PBMCs stimulated with anti-CD3. When the PBMC were enriched for CD4+ or CD8+ cells, the SEA- and anti-CD3-stimulated CD4+ cells responded far better than the CD8+ cells in the synthesis of IL-2 and incorporation of [H3]-thymidine. In the thalidomide-treated SEA-stimulated CD4+ and CD8+ cells, thalidomide acted as a costimulant to enhance the synthesis of IL-2. In the anti-CD3-stimulated thalidomide-treated cultures of PBMC enriched for CD4+ cells, thalidomide acted as a costimulant to enhance the incorporation [H3]-thymidine. Thalidomide cooperated with all of the mitogens to enhance T-cell synthesis of IL-2. However, depending on the stimulant, thalidomide could suppress or enhance PBMC incorporation of [H3]-thymidine. The SEA-stimulated cells targeted by thalidomide to suppress incorporation of [H3]-thymidine were CD4+. CD4+ cells stimulated with anti-CD3 were enhanced by thalidomide in their ability to synthesize IL-2 and to incorporate [H3]-thymidine. Increased production of IL-2 by activated T cells may be a mechanism through which thalidomide exerts its immunomodulatory effects.

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.

Thalidomide analogue CC-3052 reduces HIV+ neutrophil apoptosis in vitro

Thalidomide has significant immunomodulatory properties and has been used successfully in the treatment of oral ulcers and wasting in HIV patients. However, its use is limited by its poor bioavailability due to low solubility and short half life in solution, and teratogenic and neurotoxic side-effects. Recently, water-soluble analogues of thalidomide with significantly greater immunomodulatory activity and reduced side-effects have become available. We examined the effect of thalidomide and one analogue, CC-3052, on neutrophil apoptosis following culture for 20 h in vitro. Apoptosis was assessed by reduced CD16 expression and Annexin V binding using flow cytometry. Thalidomide or CC-3052 alone had no effect on neutrophil apoptosis when used at physiological levels. However, when used together with prostaglandin E2 (10-7 M), a potent adenylate cyclase activator, CC-3052 but not thalidomide (both 10-5 M) reduced apoptosis in neutrophils from normal and HIV+ donors. The reduced apoptosis could not be attributed to the ability of CC-3052 to reduce tumour necrosis factor-alpha (TNF-alpha) production, but may be due to its PDE4 inhibitor properties, as it increased [cAMP]i, and mimicked the effect of increasing [cAMP]i using dibutryl cAMP, a membrane-permeable analogue of cAMP. The results suggest a role for thalidomide analogue CC-3052 in reducing persistent activation of the TNF-alpha system in HIV without markedly impairing neutrophil viability.