Tumor necrosis factor-alpha levels decrease with anticytokine therapy in patients with myelodysplastic syndromes

TNF-alpha regulates the effects of irradiation in the mouse bone marrow microenvironment

Background

Secondary bone marrow (BM) myelodysplastic syndromes (MDS) are increasingly common, as a result of radio or chemotherapy administered to a majority of cancer patients. Patients with secondary MDS have increased BM cell apoptosis, which results in BM dysfunction (cytopenias), and an increased risk of developing fatal acute leukemias. In the present study we asked whether TNF-α, known to regulate cell apoptosis, could modulate the onset of secondary MDS.

Principal Findings

We show that TNF-α is induced by irradiation and regulates BM cells apoptosis in vitro and in vivo. In contrast to irradiated wild type (WT) mice, TNF-α deficient (TNF-α KO) mice or WT mice treated with a TNF-α-neutralizing antibody were partially protected from the apoptotic effects of irradiation. Next we established a 3-cycle irradiation protocol, in which mice were sub-lethally irradiated once monthly over a 3 month period. In this model, irradiated WT mice presented loss of microsatellite markers on BM cells, low white blood cell (WBC) counts, reduced megakaryocyte (MK) and platelet levels (thrombocytopenia) and macrocytic anemia, phenoypes that suggest the irradiation protocol resulted in BM dysfunction with clinical features of MDS. In contrast, TNF-α KO mice were protected from the irradiation effects: BM cell apoptosis following irradiation was significantly reduced, concomitant with sustained BM MK numbers and absence of other cytopenias. Moreover, irradiated WT mice with long term (≥5 months) BM dysfunction had increased BM angiogenesis, MMPs and VEGF and NFkB p65, suggestive of disease progression.

Conclusion

Taken together, our data shows that TNF-α induction following irradiation modulates BM cell apoptosis and is a crucial event in BM dysfunction, secondary MDS onset and progression.

Altered naive and memory CD4+ T-cell homeostasis and immunosenescence characterize younger patients with myelodysplastic syndrome

Response to immunosuppressive therapy (IST) in younger patients with myelodysplastic syndrome (MDS) has been linked to a T-cell-dominant autoimmune process that impairs hematopoiesis. Analysis of the age-adjusted CD4:CD8 ratio in 76 MDS patients compared with 54 healthy controls showed that inadequate CD4+, rather than expansion of CD8+ T cells, was associated with a lower ratio in a group that included both lower and higher risk MDS patients defined by the International Prognostic Scoring System. In younger MDS patients, naive and memory phenotypes defined by CD45RA and CD62L display showed depletion of naive CD4+ and CD8+ T cells, suggesting a possible relationship to IST responsiveness. To determine the correlation between T-cell subset distribution, T-cell turnover and autoimmunity, a cohort of 20 patients were studied before and after IST. The CD4:CD8 ratio correlated inversely with the proliferative T-cell index before treatment in IST-responsive patients, suggesting that proliferation may be linked to accelerated CD4+ T-cell turnover and hematopoietic failure. Our data show seminal findings that both CD4+ and CD8+ T-cell subsets are dysregulated in MDS. Association between these T-cell defects and response to IST suggests that aberrant T-cell homeostasis and chronic activation are critical determinants influencing autoimmune hematopoietic suppression in younger patients.

Dysregulation of IL-32 in myelodysplastic syndrome and chronic myelomonocytic leukemia modulates apoptosis and impairs NK function

TNFalpha levels are elevated in the marrows of patients with myelodysplastic syndrome (MDS) and are associated with high rates of apoptosis, which contributes to hematopoietic failure. We observed that exposure of human marrow stroma cell lines HS5 and HS27a to TNFalpha increases levels of IL-32 mRNA. IL-32, in turn, induces TNFalpha. Marrow stroma from patients with MDS expressed 14- to 17-fold higher levels of IL-32 mRNA than healthy controls. In contrast, cells from patients with chronic myelomonocytic leukemia (CMML) expressed only one tenth the level of IL-32 measured in healthy controls. Human KG1a leukemia cells underwent apoptosis when cocultured with HS5 stromal cells, but knockdown of IL-32 in the stromal cells by using siRNA abrogated apoptosis in the leukemia cells. IL-32 knockdown cells also showed dysregulation of VEGF and other cytokines. Furthermore, CD56(+) natural killer cells from patients with MDS and CMML expressed IL-32 at lower levels than controls and exhibited reduced cytotoxic activity, which was unaffected by IL-2 treatment. We propose that IL-32 is a marrow stromal marker that distinguishes patients with MDS and CMML. Furthermore, IL-32 appears to contribute to the pathophysiology of MDS and may be a therapeutic target.

Hematologic responses of patients with MDS to antithymocyte globulin plus etanercept correlate with improved flow scores of marrow cells

Myelodysplastic syndrome (MDS) comprises a spectrum of heterogeneous diseases. Most patients present with ineffective hematopoiesis. The pathophysiology involves immune-mediated effects, cytokine dysregulation, and apoptosis, among others. We treated 14 transfusion-requiring patients with MDS, 10 with refractory anemia (RA) and four with RA with excess blasts (RAEB) with a 4-day course of antithymocyte globulin (ATG) followed by intermittent etanercept for 4 months. Among 13 evaluable patients, five are red blood cell and platelet transfusion independent for intervals extending beyond 2 years, and two have normalized their peripheral blood parameters. One additional patient showed a transient rise of platelet and neutrophil counts, for an overall response rate of 46%. Responding patients showed striking improvements in marrow cell abnormalities as characterized by flow cytometry. These data show that a combination of ATG plus etanercept offers effective palliative therapy for unselected patients with MDS. Further trials incorporating these two agents are warranted.

Myelodysplastic syndromes

The myelodysplastic syndromes (MDS) are characterized by hemopoietic insufficiency associated with cytopenias leading to serious morbidity plus the additional risk of leukemic transformation. Therapeutic dilemmas exist in MDS because of the disease's multifactorial pathogenetic features, heterogeneous stages, and the patients' generally elderly ages. Underlying the cytopenias and evolutionary potential in MDS are innate stem cell lesions, cellular/cytokine-mediated stromal defects, and immunologic derangements. This article reviews the developing understanding of biologic and molecular lesions in MDS and recently available biospecific drugs that are potentially capable of abrogating these abnormalities. Dr. Peter Greenberg's discussion centers on decision-making approaches for these therapeutic options, considering the patient's clinical factors and risk-based prognostic category. One mechanism underlying the marrow failure present in a portion of MDS patients is immunologic attack on the hemopoietic stem cells. Considerable overlap exists between aplastic anemia, paroxysmal nocturnal hemoglobinuria, and subsets of MDS. Common or intersecting pathophysiologic mechanisms appear to underlie hemopoietic cell destruction and genetic instability, which are characteristic of these diseases. Treatment results and new therapeutic strategies using immune modulation, as well as the role of the immune system in possible mechanisms responsible for genetic instability in MDS, will be the subject of discussion by Dr. Neal Young. A common morphological change found within MDS marrow cells, most sensitively demonstrated by electron microscopy, is the presence of ringed sideroblasts. Such assessment shows that this abnormal mitochondrial iron accumulation is not confined to the refractory anemia with ring sideroblast (RARS) subtype of MDS and may also contribute to numerous underlying MDS pathophysiological processes. Generation of abnormal sideroblast formation appears to be due to malfunction of the mitochondrial respiratory chain, attributable to mutations of mitochondrial DNA, to which aged individuals are most vulnerable. Such dysfunction leads to accumulation of toxic ferric iron in the mitochondrial matrix. Understanding the broad biologic consequences of these derangements is the focus of the discussion by Dr. Norbert Gattermann.

Pathogenesis, classification, and treatment of myelodysplastic syndromes (MDS)

Myelodysplastic syndromes (MDS) comprise a heterogeneous group of clonal myeloid disorders characterized by morphologic dysplasia in one or more cell lineages. Dysplasia in MDS is associated with insufficient production of blood cells and consecutive cytopenia(s). The natural course and prognosis of MDS vary among patients and depend on genetic defects that occur during clonal evolution. In a significant group of patients (roughly 30%) progression to secondary leukemia is observed. These patients appear to have a grave prognosis. The treatment of patients with MDS has to be adjusted to the individual situation and age in each case. In many patients, control of blast cell production by palliative cytoreduction, continuous support with red blood cells, as well as other supportive measures, seem appropriate. In other patients, however, curative therapy (chemotherapy, stem cell transplantation) should be considered. The final decision to offer curative therapy must be based on many different factors including age and the overall situation of the patient. Recently established scoring systems aimed at predicting survival and evolution of leukemia in MDS may be helpful in this regard.

Response to erythropoietin and moxifloxacin in a patient with myelodysplastic syndrome non-respondent to erythropoietin alone

We describe a low-risk myelodysplastic syndrome patient who did not respond to erythropoietin alone, but who did show a major erythroid response to combination therapy consisting of erythropoietin and moxifloxacin. This observation was exclusively empirical. The immunomodulatory effects of moxifloxacin may explain the synergy with erythropoietin.

A pilot study of the recombinant soluble human tumour necrosis factor receptor (p75)-Fc fusion protein in patients with myelodysplastic syndrome

Laboratory observations suggest that, in some myelodysplastic syndromes (MDS), immune mechanisms may contribute to the impaired blood cell production. Tumor necrosis factor alpha (TNF-alpha), a potent inhibitor of haematopoiesis, has been hypothesized to mediate suppressive effects in MDS: TNF-alpha levels are elevated and correlated with marrow apoptosis and cytopenia. Inhibition of TNF-alpha production using the soluble TNF receptor (Enbrel) has been successful in rheumatoid arthritis, and we have now applied the same principle to MDS. We determined spontaneous TNF-alpha production by marrow cells in MDS; TNF-alpha production was elevated (> mean + 2 x SD of controls) in > 1/3 of patients, but did not correlate with clinical parameters. Sixteen patients participated in a 3-month pilot study of Enbrel. The drug was well tolerated and 15 patients were evaluable. Of these, one became temporarily (14 weeks) transfusion independent. In another patient, absolute neutrophil count (ANC) rose from 0.5 x 10(9)/l to 0.84 x 10(9)/l. Serious infections were seen in two out of six neutropenic patients. Progression to refractory anaemia with excess blasts in transformation (RAEBt) or leukaemia was observed in three patients. When the effects of Enbrel on haematopoietic colony formation were studied, no significant increase was seen in MDS and there was no correlation with TNF-alpha levels. Although anti-TNF therapy with Enbrel was well tolerated at the dosages used in MDS, its efficacy as a single agent appears low.

Soluble TNF receptor fusion protein (etanercept) for the treatment of myelodysplastic syndrome: a pilot study

Blockade of tumor necrosis factor (TNF)alpha by a soluble TNF receptor fusion protein (etanercept; Enbrel) improved in vitro hemopoiesis from the marrow of patients with myelodysplastic syndrome (MDS). Therefore, we enrolled 14 MDS patients (4 RA, 2 RARS, 6 RAEB, 2 CMML), 44-80 (median 60) years old, in a pilot trial. Etanercept, 25 mg, was given twice a week s.c. for 16 weeks (increased to three times a week if no response at 8 weeks). Among 12 evaluable patients, four had rises in hemoglobin by 1-1.5 gm/dl (three) or decreased transfusion requirements (one). Two patients had increased platelet counts (54% and 73%), and two increased neutrophils (63% and 120%). Baseline TNFalpha levels, determined in all patients, did not correlate with responses. Among eight marrows available for sequential in vitro assays, four showed increases in CFU-GM of 1.5- to 5-fold at 8 weeks, whereas three showed 3- to 10-fold decrements relative to baseline. Thus, etanercept treatment resulted in moderate improvements of cytopenias in some patients, while cell counts declined in others. Additional trials are needed to evaluate its clinical efficacy in MDS.

Management of high-risk myelodysplastic syndromes

The myelodysplastic syndromes (MDS) are a group of clonal disorders characterized by one or more cytopenias secondary to bone marrow dysfunction. The percentage of bone marrow blasts, the number of cytopenic cell lines and cytogenetics define more precisely clinical risk groups. In the high-risk MDS, the time for evolution to acute myeloid leukemia (AML) is between 0.2 and 1.1 years and the median survival has been evaluated between 0.4 and 1.2 years. Progress in the understanding the biology of MDS and the development of accurate prognostic classification systems have allowed a risk-adapted treatment strategy in individual patients. Some high-risk MDS patient categories may benefit from intensive cytotoxic treatment. Allogeneic stem cell transplantation (alloSCT) from donors remains the treatment of choice for younger patients. Autologous stem cell transplantation (ASCT) may provide a suitable alternative for those patients without a sibling donor or for older patients' categories. New regimens using non-myeloablative stem cell transplantation followed by donor lymphocyte infusions (DLI) are underway and have achieved promising results in HLA-identical transplantation, resulting in reduced morbidity and mortality and confirming that this approach is feasible in patients ineligible for conventional allografting due to age and/or organ toxicity. Other therapeutic strategies include new low-dose treatments, antiapoptotic agents such as amifostine and anticytokine therapy, which are currently under investigation and deserve further evaluation. More insights into the biology of the disease, the discovery of new therapeutic approaches and the search for better ways to use existing strategies may lead to more effective treatments.

Oral pentoxifylline inhibits release of tumor necrosis factor-alpha from human peripheral blood monocytes : a potential treatment for aseptic loosening of total joint components

BACKGROUND

Pentoxifylline (Trental) is a methylxanthine-derivative drug that has been used for more than twenty years in the treatment of peripheral vascular disease. Pentoxifylline is also a potent inhibitor of tumor necrosis factor-alpha (TNF-alpha) secretion, both in vitro and in vivo, and has demonstrated efficacy in the treatment of certain animal and human inflammatory diseases. Pentoxifylline has a potential therapeutic role in the treatment of aseptic loosening of total joint replacement components because it inhibits TNF-alpha secretion by particle-stimulated human peripheral blood monocytes. The purpose of our study was to determine whether the particle-stimulated secretion of TNF-alpha by peripheral blood monocytes was inhibited in volunteers who had received pentoxifylline orally.

METHODS

Human peripheral blood monocytes were harvested from eight healthy volunteers and were exposed to three different concentrations of titanium particles or to 500 ng/mL of lipopolysaccharide as a positive control. The same volunteers were then given pentoxifylline (400 mg, five times per day) for seven days. Their peripheral blood monocytes were again isolated and exposed to experimental conditions, and the TNF-alpha levels were measured.

RESULTS

The peripheral blood monocytes from all eight volunteers showed a significant reduction in TNF-alpha release following oral treatment with pentoxifylline. This reduction was observed at exposures of 10(7) and 10(6) titanium particles/mL and in the lipopolysaccharide-treated group, but not at 10(5) particles/mL.

CONCLUSIONS

To our knowledge, this is the first study to demonstrate the ability of an oral drug to decrease the release of TNF-alpha from human peripheral blood monocytes exposed ex vivo to particle debris. TNF-alpha is involved in the pathogenesis of osteolysis and subsequent loosening of total joint arthroplasty components. The ability to suppress the release of TNF-alpha in patients with a total joint replacement may help to control osteolysis and to reduce the development of aseptic loosening. This effect could increase implant longevity and decrease the need for revision arthroplasty.

Excessive apoptosis in low risk myelodysplastic syndromes (MDS)

The paradox of peripheral cytopenias despite a normo/hypercellular marrow in MDS has been ascribed to excessive intramedullary hematopoietic cell apoptosis. Programmed cell death (PCD) in early disease might be triggered by the BM microenvironment, mediated either through inhibitory cytokines such as tumor necrosis factor alpha (TNF-alpha) or fas/fas ligand signaling or through a relative deficiency in hematopoietic growth factors. Intrinsic cellular defects giving rise to abnormalities in cell-cell or cell-stromal interaction, cell signaling or cell cycling may also underlie hematopoietic progenitor apoptosis. Alternatively, an early 'hit' in the multistep pathogenesis of MDS may result in a higher proliferative rate of the neoplastic clone. Increased apoptosis may thus represent a homeostatic process to control cell numbers. This paper shall summarize current evidence implicating a role for increased PCD in low risk MDS, outline possible etiologic factors and suggest potential therapeutic mechanisms whereby excessive hematopoietic progenitor cell apoptosis might be circumvented.

Increased apoptosis of bone marrow cells and preserved proliferative capacity of selected progenitors predict for clinical response to anti-inflammatory therapy in myelodysplastic syndromes

To determine the relation of apoptosis and clonal proliferation in the bone marrow (BM) to the effectiveness of a therapeutic protocol described to downmodulate monokine activity in patients with myelodysplastic syndromes (MDS). Prior to protocol therapy, BM stroma was cultivated and selected CD34(+) cells were studied in stroma and cytokine-dependent clonogenic assays. The TUNEL assay was used to establish the degree of apoptosis occurring in the marrow and CD34(+) population. The effectiveness of oral ciproloxacin 500 mg b. i.d., pentoxifylline 800 mg t.i.d., and dexamathasone 4 mg t.i.d. (CPD) antiinflammatory therapy was correlated with the intensity of cell apoptosis and proliferation of BM progenitor cells. Seventeen patients were studied. Twelve patients (10 transfusion dependent) received therapy for a median of 99 days (range 49-284). Toxicity caused four patients to discontinue the drug combination. Six patients fulfilled response criteria. Four patients became transfusion independent, and 50% reduction in the need for blood transfusions was noted in one patient. Blood parameters of one untransfused patient increased by >30%. Blood count remained unsupported in three patients, even at a median of 12 months after trial discontinuation. Apoptosis of marrow cells and selected CD34(+) progenitors was detected in a median of 49.5% (range 3. 6%-90%) and 10.6% (range 3.6%-100%; p < 0.01), respectively. In patients who responded to therapy, the median apoptosis rate in the bone marrow population was 71%, in contrast to the nonresponder's rate of 13% (p = 0.002). Overall clonogenic growth of selected precursors corresponded significantly with response to CPD protocol (p = 0.004). In some patients with MDS, ineffective hematopoiesis is related to high apoptotic index despite proliferation of the CD34(+) precursors. These patients seem to benefit from CPD cytokine modulatory therapeutic strategy.

Anti-TNF therapies in rheumatoid arthritis, Crohn's disease, sepsis, and myelodysplastic syndromes

An attempt has been made in this article to summarize the state-of-the-art clinical experience with the use of anti-TNF therapies in four diseased states with special emphasis on myelodysplastic syndromes. Given the central role of TNF-alpha in initiating and perpetuating the chronic damage produced in the diseased organs by controlling a cascade of pro-inflammatory cytokines, as well as its acute role in sepsis, theoretically speaking, neutralization of this peptide was a natural therapeutic choice. Results of the initial clinical trials appear encouraging and sometimes dramatic in their efficacy. The mechanism of response however, is interesting in that even when TNF-alpha is directly targeted by a monoclonal antibody, the resulting benefits can frequently not be attributed to TNF suppression alone. Rather, it appears that a more general effect on the T-lymphocytes is also contributing to the responses being seen. This raises the new possibility of combining anti-cytokine and anti-T-cell strategies to treat at least the more chronic diseases such as Crohn's disease and myelodysplastic syndromes. Continued clinical trials testing these strategies are clearly warranted.

Patients with myelodysplastic syndromes benefit from palliative therapy with amifostine, pentoxifylline, and ciprofloxacin with or without dexamethasone

Thirty-five patients with myelodysplastic syndrome (MDS) were registered on protocol MDS 96-02 and were receiving continuous therapy with pentoxifylline 800 mg 3 times a day and ciprofloxacin 500 mg twice a day by mouth; dexamethasone was added to the regimen for the partial responders and the nonresponders after 12 weeks at a dose of 4 mg by mouth every morning for 4 weeks. Amifostine was administered intravenously 3 times a week at 3 dose levels (200 mg/M2, 300 mg/M2, and 400 mg/M2) to cohorts of 10 patients each. Therapy has been continued for 1 year in responders. Twenty-nine have completed at least 12 weeks of therapy and are available for response evaluation. Of the 21 men and 8 women (median age, 67 years), 20 had refractory anemia (RA), 3 had RA with ringed sideroblasts (RARS), 5 had RA with excess blasts (RAEB), and 1 had chronic myelomonocytic leukemia (CMMoL). Five had secondary MDS. No differences were noted in response rates among the 3 dose levels. Seven patients did not respond at all, and 22 showed an improvement in cytopenias (76%). Three had a triple lineage response, 10 had a double lineage response, and 9 had a single lineage response (8 of 9 in absolute neutrophil count [ANC] and 1 had more than a 50% reduction in packed red blood cell transfusions). Fifteen patients responded only after the addition of dexamethasone, whereas 7 responded before. When examined by lineage, 19 of 22 showed improved ANC, 11 of 22 demonstrated more than 50% reduction in blood transfusions, improved Hb levels, or both, and 7 of 22 showed improvement in platelet counts. Interestingly, the responses were frequently slow to appear, and continued improvement in counts was seen up to 12 months of therapy and beyond. This study supports the feasibility of treating patients with MDS with the unique approach of cytoprotection and anticytokine therapies as well as the principle that prolonged commitment to treatment is desirable when noncytotoxic agents are administered.

Efficacy of N-acetylcysteine and all-trans retinoic acid in restoring in vitro effective hemopoiesis in myelodysplastic syndromes

We evaluated the in vitro effect on clonogenic potential (CFU-GM) and apoptosis in myelodysplastic syndromes (MDS) progenitors of an anti-oxidant (N-acetylcysteine, NAC) and/or a differentiating (all-trans retinoic acid, ATRA) agent. NAC significantly reduced apoptosis, both NAC and ATRA induced an increase in CFU-GM, but NAC seemed to be particularly effective in the high risk (HR) MDS. NAC + ATRA conferred a significant advantage in terms of CFU-GM with respect to NAC and ATRA alone. Tumor Necrosis Factor-alpha (TNF-alpha) levels decreased after incubation with NAC in the MDS samples. This study shows that ineffective hemopoiesis in MDS could benefit from both NAC and ATRA, suggesting that anti-oxidant treatment may play a role in guaranteeing MDS cell survival, predisposing them towards differentiation.

Consilience across evolving dysplasias affecting myeloid, cervical, esophageal, gastric and liver cells: common themes and emerging patterns

In the present paper, an attempt is made to identify common biologic themes across dysplastic states affecting the marrow, gastro intestinal tissue, the cervix and liver as well as unifying patterns during disease evolution. The following algorithm appears generally applicable, although individual variations must necessarily be anticipated. It appears that there is an initial transforming event which in all dysplasias except that affecting the marrow has been found to be infectious. Increased cellular proliferation-increased apoptosis, telomere shortening, appearance of telomerase expression and clonal expansion follow the initial insult. Abnormalities in the cytokine environment are universally described and it is likely that the quintessential monoclonality aspect of dysplasia predisposes to accumulation of genetic mutations, and microsatellite instability leading to the appearance of evolved sub-clones. The conversion of a dysplastic phenotype to a malignant one reflects the success of one such sub-clone in developing a survival advantage over a large population of prematurely apoptotic neighbors. This state is usually acquired by silencing tumor suppressor genes through hypermethylation or actual loss or dysfunction. Thus, excessive apoptosis of cells resulting from a persistent infectious process predisposes the organ towards developing a cancerous phenotype. Evidence for the shared pathology is presented at length with the hope that these parallels between dysplastic states will be helpful in both biologic and therapeutic research.