Failure of recombinant human interleukin-3 therapy to induce erythropoiesis in patients with refractory Diamond-Blackfan anemia [see comments]

In two previous studies, we observed that recombinant human interleukin- 3 (IL-3) induced an increase in marrow burst-forming unit-erythroid- derived colonies in vitro in some patients with Diamond-Blackfan anemia (DBA). To determine whether a similar erythropoietic response could be induced in vivo, we treated 13 patients with DBA (aged 4 to 19 years) with two preparations of IL-3. All patients had absent absolute reticulocyte counts and markedly reduced to absent recognizable bone marrow erythroid elements; patients with circulating reticulocytes in the previous 12 months were excluded from study. All patients except 1 had failed steroid therapy and had been transfusion-dependent since infancy; 1 patient was maintained on high-dose prednisone at the time of enrollment. On the first arm of the study, IL-3 (Immunex Corp, Seattle, WA) was administered subcutaneously using a dose escalation regimen of 125 to 500 micrograms/m2/day in divided dosage at 12-hour intervals, coadministered with 1.5 mg/kg/d of oral ferrous sulphate. Of the 13 patients that entered the trial, 4 stopped prematurely because of adverse side effects. In the other 9 evaluable cases, reticulocytes increased transiently in 1 patient from 0 to 65 x 10(9)/L after 35 days of IL-3 therapy at 250 micrograms/m2, but transfusion dependency persisted. One transient peak in absolute reticulocyte count was noted in 6 other patients, but no erythroid response was observed after completion of a full course of IL-3. Oral prednisone at 0.5 mg/kg/d was then coadministered with IL-3 at 500 micrograms/m2 to 5 of the patients without effect, and treatment was stopped. In 2 patients, a second preparation of IL-3 (Sandoz Canada Inc, Dorval, Quebec, Canada) was initiated in a dose escalation regimen of 2.5 to 10 micrograms/kg and was coadministered with ferrous sulphate. No erythroid response was observed in either patient, and in one of the two, alternate-day subcutaneous recombinant erythropoietin at 300 U/kg was administered for 3 weeks in combination with daily IL-3 at 10 micrograms/kg, but no increased erythropoiesis was seen. Significant increases in white blood cell and eosinophil counts during administration of both preparations of IL-3 were observed in all patients. These data show that the response of DBA patients to IL-3 in vivo is heterogeneous and cannot be predicted from in vitro studies. The absence of a corrective effect of IL-3 in these patients with DBA indicates that a deficiency of the cytokine is not central in the pathogenesis of the disorder.     

Dexamethasone resistance in B-cell precursor childhood acute lymphoblastic leukemia occurs downstream of ligand-induced nuclear translocation of the glucocorticoid receptor

Glucocorticoids are among the most effective agents used in the treatment of childhood acute lymphoblastic leukemia (ALL), and patient response to treatment is an important determinant of long-term outcome. Despite its clinical significance, the molecular basis of glucocorticoid resistance in lymphoid malignancies is still poorly understood. We have recently developed a highly clinically relevant experimental model of childhood ALL, in which primary childhood ALL biopsies were established as xenografts in nonobese diabetic/severe combined immunodeficient (NOD/SCID) mice. The in vivo and in vitro responses of a panel of these xenografts to the glucocorticoid, dexamethasone, reflected the outcome of the patients from whom they were derived. In this report we show that glucocorticoid resistance in B-cell precursor (BCP) ALL xenografts was not due to down-regulation of the glucocorticoid receptor (GR) nor to defective ligand binding of the GR. Moreover, dexamethasone-induced GR translocation from the cytoplasm to the nucleus was comparable in all xenografts. However, glucocorticoid resistance was associated with profoundly attenuated induction of the BH3-only proapoptotic protein, Bim, when xenograft cells were exposed to dexamethasone. These results show that dexamethasone resistance in BCP ALL xenografts occurs downstream of ligand-induced nuclear translocation of the GR, but upstream of Bim induction.     

Tim-3 enhances FcεRI-proximal signaling to modulate mast cell activation

T cell (or transmembrane) immunoglobulin and mucin domain protein 3 (Tim-3) has attracted significant attention as a novel immune checkpoint receptor (ICR) on chronically stimulated, often dysfunctional, T cells. Antibodies to Tim-3 can enhance antiviral and antitumor immune responses. Tim-3 is also constitutively expressed by mast cells, NK cells and specific subsets of macrophages and dendritic cells. There is ample evidence for a positive role for Tim-3 in these latter cell types, which is at odds with the model of Tim-3 as an inhibitory molecule on T cells. At this point, little is known about the molecular mechanisms by which Tim-3 regulates the function of T cells or other cell types. We have focused on defining the effects of Tim-3 ligation on mast cell activation, as these cells constitutively express Tim-3 and are activated through an ITAM-containing receptor for IgE (FcεRI), using signaling pathways analogous to those in T cells. Using a variety of gain- and loss-of-function approaches, we find that Tim-3 acts at a receptor-proximal point to enhance Lyn kinase-dependent signaling pathways that modulate both immediate-phase degranulation and late-phase cytokine production downstream of FcεRI ligation.T cell, or transmembrane, immunoglobulin domain and mucin domain (Tim-3) is a type I membrane protein expressed on a variety of innate and adaptive immune cell types. Tim-3 is often referred to as a checkpoint receptor due to its apparent inhibitory function on T cells and its association with activation-induced T cell exhaustion in tumors and chronic viral infection (Sánchez-Fueyo et al., 2003; Jones et al., 2008; Fourcade et al., 2010; Jin et al., 2010; Sakuishi et al., 2010). Recent studies, however, suggest a more nuanced picture of Tim-3 function in T cells, depending on the setting, e.g., acute versus chronic stimulation (Ferris et al., 2014; Gorman and Colgan, 2014). In addition to CD4 and CD8 T cells, Tim-3 is also expressed on other immune cell types, such as NK cells, macrophages, DCs, and mast cells, but its function on these cell types is less clear. Tim-3 blockade was shown to enhance macrophage function in response to sepsis (Yang et al., 2013), and also to regulate antigen (Ag) presentation by DCs, partly through Btk and c-Src (Maurya et al., 2014). On the other hand, Tim-3 expression on monocytes infiltrating the CNS during EAE was shown to promote inflammation (Anderson et al., 2007).Mast cells are first-line defenders against allergens and invading pathogens as a result of their proximity to the external environment. Cross-linking of IgE bound to the high-affinity IgE receptor FcεRI by Ag leads to the release of preformed mediators and de novo synthesis of proinflammatory and antiinflammatory mediators and cytokines, which together serve to regulate hypersensitivity, autoimmunity, cardiovascular disease, and tumor progression (Kalesnikoff and Galli, 2008). In addition to their well-known pathological roles in allergic responses, mast cells also contribute to defense against bacteria, helminthes, and tumors (Abraham and St John, 2010). It was reported that mast cells constitutively express cell surface Tim-3, and that cross-linking of Tim-3 could enhance cytokine production of IgE-sensitized and Ag-stimulated BM-derived mast cells (BMMCs) and peritoneal mast cells (pMCs) without affecting degranulation (Nakae et al., 2007). TGF-β has been shown to up-regulate expression of Tim-3 in tumor-infiltrating mast cells and a human mast cell line, through a mitogen-activated protein kinase Erk-kinase (MEK)–dependent pathway (Wiener et al., 2006; Yoon et al., 2011). Although previous data suggest that Tim-3 is a positive regulator of mast cell activation, the molecular mechanisms behind the contribution of Tim-3 to mast cell function are still unknown. Importantly, there was until now no genetic evidence addressing the function of Tim-3 in these cells. Given the important role of mast cells as sentinels in both allergic and nonallergic diseases, it is of interest to explore Tim-3 activity on this cell type and how antibody (Ab) modulation can affect its function.Here, we demonstrate through multiple approaches that Tim-3 functions to enhance proximal FcεRI signaling in mast cells. Cross-linking of Tim-3 with multiple independent antibodies enhanced mast cell degranulation and cytokine release in a dose-dependent manner. Acute knock-down or genetic deficiency of Tim-3 rendered mast cells less responsive to Ag cross-linking of FcεRI, resulting in decreased degranulation and cytokine production. The cytoplasmic tail of Tim-3 was required for co-stimulatory signal transduction in mast cells, together with FcεRI signaling pathways. This was shown in part with the use of recently reported Nur77-GFP transgenic models, which have not previously been used for the study of FcεRI signaling. Collectively, our data demonstrate that Tim-3 acts at a receptor-proximal level to intensify activation of FcεRI-dependent signaling pathways upon Ag cross-linking, while maintaining the threshold for negative signaling of Lyn.     

Active tuberculosis in inflammatory bowel disease patients under treatment from an endemic area in Latin America

BACKGROUNDThere has been an increase in cases of inflammatory bowel disease (IBD) in recent years. There is also greater access and availability of immunosuppressive and biological agents, which increase the risk of opportunistic infection despite improving the quality of life and promoting mucosal healing. Tuberculosis (TB) remains a public health problem, and it has a high incidence in several countries. Therefore, knowledge of the risk of developing TB in patients with IBD is important.AIMTo evaluate the risk of active TB in patients with IBD under treatment from an endemic area in Latin America.METHODSA standard questionnaire included demographic variables, clinical aspects of IBD disease, history of active TB during treatment, active TB characteristics and evolution, initial screening and results and time from the start of anti-tumor necrosis factor alpha (TNFα) to TB development.RESULTSAzathioprine, anti-TNFα and the combination of these two drugs were associated with a higher risk of active TB incidence. The TNFα blockers increased the relative risk of developing active TB compared to other treatments. All four multivariable models showed that the use of TNFα blockers alone or in combination with azathioprine was an important risk factor for the incidence of active TB. After adjustment for sex, age, type of IBD and latent TB, anti-TNFα with azathioprine increased the relative risk to 17.8 times more than conventional treatment. Late TB, which was diagnosed 3 mo after the start of anti-TNFα, was the most frequent.CONCLUSIONTreatment with anti-TNFα increased the risk of active TB in IBD patients from an endemic area in Latin America. This risk was increased when anti-TNFα was combined with azathioprine. The time from the beginning of the treatment to the active TB diagnosis suggests a new TB infection.     

Parkinson’s disease: considerations for dental hygienists

Abstract: The prevalence of Parkinson’s disease (PD) is expected to double over the next 20 years owing to the increase in life expectancy. This progressive disease has several implications relating to oral health, and many are manageable with proper awareness and knowledge about the disease. This article reviews the epidemiology, pathophysiology, and characteristics of PD, as well as the treatments and oral health considerations to enable dental hygienists to undertake an informed approach to patient management strategies and provide optimal care.