Long-term outcome of 25 children and adolescents with severe aplastic anemia treated with antithymocyte globulin

Severe aplastic anemia (SAA) is probably an immune-mediated disorder, and immunosuppressive therapy is recommended for patients with no available donor for bone marrow transplant. Between October 1984 and November 1987, 25 consecutive children and adolescents with SAA with no HLA-compatible marrow donor received equine antithymocyte globulin (ATG) (15 mg kg-1 day-1) for 10 days. The patients were evaluated 6 weeks, 6 months, and 12 months after starting ATG treatment. Thereafter, patients were evaluated yearly until July 1998. Median age was 10 years (range, 1.5-20 years), granulocyte counts on referral ranged from 0.032 to 1.4 x 10(9)/l (median 0.256 x 10(9)/l), and 12 patients had granulocyte counts <0.2 x 10(9)/l. At a median follow-up of 9.6 years (range, 8.6-11.8 years), 10 patients (40%) remained alive with good marrow function. No morphologic evidence of hematological clonal disorders has been observed, although two patients probably have acquired clonal chromosomal abnormalities (trisomy 8 and del(6)q21, respectively). Responses to ATG were observed between 6 weeks and 6 months from the start of treatment in 60% of evaluable patients. The response rate was not different in patients whose granulocyte count at diagnosis was <0.2 x 10(9)/l, or in those who were <10 years of age. This study supports the view that, when compared with supportive measures, ATG is an effective treatment for children or adolescents with SAA. Although these results are inferior to those reported for marrow transplantation or more intensive immunosuppressive regimens, these patients who responded to ATG are long-term survivors with stable peripheral blood counts and a low rate of relapse.

Acyl glucuronide reactivity in perspective: biological consequences

The metabolic conjugation of exogenous and endogenous carboxylic acid substrates with endogenous glucuronic acid, mediated by the uridine diphosphoglucuronosyl transferase (UGT) superfamily of enzymes, leads to the formation of acyl glucuronide metabolites. Since the late 1970s, acyl glucuronides have been increasingly identified as reactive electrophilic metabolites, capable of undergoing three reactions: intramolecular rearrangement, hydrolysis, and intermolecular reactions with proteins leading to covalent drug-protein adducts. This essential dogma has been accepted for over a decade. The key question proposed by researchers, and now the pharmaceutical industry, is: does or can the covalent modification of endogenous proteins, mediated by reactive acyl glucuronide metabolites, lead to adverse drug reactions, perhaps idiosyncratic in nature? This review evaluates the evidence for acyl glucuronide-derived perturbation of homeostasis, particularly that which might result from the covalent modification of endogenous proteins and other macromolecules. Because of the availability of acyl glucuronides for test tube/in vitro experiments, there is now a substantial literature documenting their rearrangement, hydrolysis and covalent modification of proteins in vitro. It is certain from in vitro experiments that serum albumin, dipeptidyl peptidase IV, tubulin and UGTs are covalently modified by acyl glucuronides. However, these in vitro experiments have been specifically designed to amplify any interference with a biological process in order to find biological effects. The in vivo situation is not at all clear. Certainly it must be concluded that all humans taking carboxylate drugs that form reactive acyl glucuronides will form covalent drug-protein adducts, and it must also be concluded that this in itself is normally benign. However, there is enough in vivo evidence implicating acyl glucuronides, which, when backed up by in vivo circumstantial and documented in vitro evidence, supports the view that reactive acyl glucuronides may initiate toxicity/immune responses. In summary, though acyl glucuronide-derived covalent modification of endogenous macromolecules is well-defined, the work ahead needs to provide detailed links between such modification and its possible biological consequences. (C) 2003 Elsevier Science Ireland Ltd. All rights reserved.

Tityus serrulatus venom and toxins Ts1, Ts2 and Ts6 induce macrophage activation and production of immune mediators

Scorpion envenomation induces a systemic immune response, and neurotoxins of venom act on specific ion channels, modulating neurotransmitter release or activity. However, little is known about the immunomodulatory effects of crude venom from scorpion Tityus serrulatus (TsV) or its toxins (Ts1, Ts2 and Ts6) in combination with lipopolysaccharide (LPS). To investigate the immunomodulatory effects of TsV and its toxins (Ts1, Ts2 and Ts6), J774.1 cells were stimulated with different concentrations (25, 50 and 100 mu g/mL) of venom or toxins pre-stimulated or not with LPS (0.5 mu g/mL). Macrophage cytotoxicity was assessed, and nitric oxide (NO) and cytokine production were analyzed utilizing the culture supernatants. TsV and its toxins did not produce cytotoxic effects. Depending on the concentrations used, TsV, Ts1 and Ts6 stimulated the production of NO, interleukin (IL)-6 and tumor necrosis factor (TNF)-alpha in J774.1 cells, which were enhanced under LPS co-stimulation. However, LPS + Ts2 inhibited NO, IL-6 and TNF-alpha production, and Ts2 alone stimulated the production of IL-10, suggesting an anti-inflammatory activity for this toxin. Our findings are important for the basic understanding of the mechanisms involved in macrophage activation following envenomation: additionally, these findings may contribute to the discovery of new therapeutic compounds to treat immune-mediated diseases. (C) 2011 Elsevier Ltd. All rights reserved.

O papel da angiogênese e da hemólise na úlcera de perna de pessoas com anemia falciforme

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Study of chronic hemolytic anaemia patients in Rio de Janeiro: prevalence of anti-human parvovirus B19 IgG antibodies and the developement aplastic crises

The prevalence of anti-human parvovirus B19 IgG antibodies was determined in sera from 165 chronic hemolytic anemia patients, receiving medical care at Instituto Estadual de Hematologia (IEHE), Rio de Janeiro, during the year of 1994. This sample represents around 10% of the chronic hemolytic anemia patients attending at IEHE. Most of these patients (140) have sickle cell disease. Anti-B19 IgG antibodies were detected in 32.1% of patients. No statistically significant difference (p > 0.05) was seen between IgG antibody prevalence in male (27.8%) and female (35.5%) patients. Anti-B19 IgG antibodies were more frequent in older (37.6%) than younger (28.2%) than 20 years old patients, although this difference had no statistical significance (p > 0.05). Anti-B19 IgG antibody prevalence showed that 67.9% of patients enrolled in the study were susceptible to B19 acute infection. With the aim to detect acute B19 infection, patients follow up continued until February 1996. During this period four patients presented transient aplastic crisis due to human parvovirus B19 as confirmed by the detection of specific IgM antibodies. All four patients were younger than 20 years old, and 3 were younger than 10 years old. Three of them were sickle cell disease patients. Three of the four acute B19 infection occurred during 1994 springtime.

Immune response and tissue cytoprotection: two sides of the same coin in immunopathology

Dissertation presented to obtain the Ph.D degree in Biochemistry

Cytokines and T-Lymphocute count in patients in the acute and chronic phases of Bartonella bacilliformis infection in an endemic area in peru: a pilot study

Human Bartonellosis has an acute phase characterized by fever and hemolytic anemia, and a chronic phase with bacillary angiomatosis-like lesions. This cross-sectional pilot study evaluated the immunology patterns using pre- and post-treatment samples in patients with Human Bartonellosis. Patients between five and 60 years of age, from endemic areas in Peru, in the acute or chronic phases were included. In patients in the acute phase of Bartonellosis a state of immune peripheral tolerance should be established for persistence of the infection. Our findings were that elevation of the anti-inflammatory cytokine IL-10 and numeric abnormalities of CD4+ and CD8+ T-Lymphocyte counts correlated significantly with an unfavorable immune state. During the chronic phase, the elevated levels of IFN-γ and IL-4 observed in our series correlated with previous findings of endothelial invasion of B. henselae in animal models.

Prevention of bone marrow graft failure by an anti LFA-1 monoclonal antibody

Graft rejection is the major cause of failure of HLA mismatched bone marrow transplantation because of residual host immunity. we have proposed to use a monoclonal murine antibody specific for the LFA-1 molecule (25-3) to prevent graft failure in HLA mismatched bone marrow transplantation (BMT). The rationale for this approach is three fold: LFA-1 deficient patients (3/3) do not reject HLA mismatched BMT; anti LFA-1 blocka in vitro the induction of T cell responses and T/ non T cytotoxic functions; LFA-1 is not expressed by other cells than leucocytes. We have accordingly treated twenty two patients with inherited diseases and 8 with leikemia. The bone marrow was T cells depled by E rosetting of Campath antibody. The antibody was given at days -3, -1, +1, +3, +5 at dose of .1 mg/kg/d for the first 9 and then .2mg/kg/d from day -3 to +6. Engraftment occured in 23/30 patients as shown by at least HLA typing. Hematological recovery was rapid, GVH was limited. Side effects of antibody infusion included fever and possibly an increased incidence of early bacteral infection (sepsis, 1 death). Immunological reconstitution occured slowly leading in six cases to EBV-induced B cell poliferation (1 death and in two others to transient auto immune hemolytic anemia. There has been only one secondary graft rejection. Sisteen patients are alive 3 to 26 months post transplant with functional grafts. Although the number of patients treated is still low the absence of late rejection so far, gives hope for long term maintenance of the graft using anti LFA-1. Since the antibody is an IgG 1 unable to bind human complement, and since it is known to inhibit phagocytosis, there is a good suggestion that 25-3 act through functional blocking of host T and non T luymphocytes at both induction and effector levels.

Treatment of atypical hemolytic uremic syndrome and thrombotic microangiopathies: a focus on eculizumab.

Uncontrolled complement activation is central to the occurrence of atypical hemolytic uremic syndrome (aHUS) and can result in thrombotic microangiopathies (TMAs).These terms encompass a group of heterogenic inherited or acquired diseases that recent research suggests may be triggered by the complement cascade. Pathogenetic triggers of complement activation include immunologic disorders, genetics, infections, systemic diseases, pregnancy, drug administration, metabolic diseases, transplantation, or triggers of mixed cause. Hallmarks of aHUS and other TMAs include increased vascular endothelium thromboresistance, leukocyte adhesion to damaged endothelium, complement consumption, coagulation abnormalities, and vascular shear stress, whereas common end points of these mechanisms include hemolytic anemia, thrombocytopenia with microvascular infarction, and predisposition for decreased kidney function and other organ involvement. The central role of the complement cascade as a disease trigger suggests a possible therapeutic target. Eculizumab, a first-in-class humanized monoclonal anti-C5 antibody that has been successful in the treatment of paroxysmal nocturnal hemoglobinuria, a disorder of complement-induced hemolytic anemia, received approval for the treatment of aHUS in the United States and Europe in late 2011. We review the treatment of aHUS and other TMAs, focusing on the role of eculizumab, including its pharmacology, mechanism of action, and approved dosing recommendations and health economic considerations. Finally, the potential for future indications for eculizumab use in other complement-driven diseases is discussed.

Role of defensins and cathelicidin LL37 in auto-immune and auto-inflammatory diseases.

Defensins and cathelicidins are anti-microbial peptides (AMPs) that act as natural antibiotics and are part of the innate immune defence in many species. We consider human defensins and LL37, the only human member of the cathelicidin family. In particular, we refer to the human alpha-defensins called human neutrophil peptides (HNP1 through 4), which are produced by neutrophils, HD5 and HD6, mainly expressed in Paneth cells of intestine, the human beta-defensins HBD1, HBD2 and HBD3, synthesized by epithelial cells and LL37, which is located in granulocytes, but is also produced by epithelial cells of the skin, lungs, and gut. In the last years, the study of AMPs activity and regulation has allowed to understand the important role of these peptides not only in the innate defence mechanisms against bacteria, viruses, fungi, but also in the regulation of immune cell activation and migration. Complementary studies have disclosed a role for AMPs in modulating many physiological processes that involve non-immune cells, such as activation of wound healing, angiogenesis, cartilage remodeling. Due to the pleiotropic tasks of these peptides, many of them are now being discovered to contribute to immune pathology of chronic diseases that affect skin, gut, joints; this is supported by many examples of immune-mediated pathologies in which their expression is disregulated. In this article we review the current literature that suggests a role for human defensins and LL37 in pathogenic mechanisms of several chronic diseases that are considered of auto-immune or auto-inflammatory origin.

Role of Leptin in the Activation of Immune Cells

Adipose tissue is an active endocrine organ that secretes various humoral factors (adipokines), and its shift to production of proinflammatory cytokines in obesity likely contributes to the low-level systemic inflammation that may be present in metabolic syndrome-associated chronic pathologies such as atherosclerosis. Leptin is one of the most important hormones secreted by adipocytes, with a variety of physiological roles related to the control of metabolism and energy homeostasis. One of these functions is the connection between nutritional status and immune competence. The adipocyte-derived hormone leptin has been shown to regulate the immune response, innate and adaptive response, both in normal and pathological conditions. The role of leptin in regulating immune response has been assessed in vitro as well as in clinical studies. It has been shown that conditions of reduced leptin production are associated with increased infection susceptibility. Conversely, immune-mediated disorders such as autoimmune diseases are associated with increased secretion of leptin and production of proinflammatory pathogenic cytokines. Thus, leptin is a mediator of the inflammatory response

Thrombosis in paroxysmal nocturnal hemoglobinuria at a glance: a clinical review.

Paroxysmal nocturnal hemoglobinuria (PNH) is a rare, acquired stem cell disorder, with its primary clinical manifestations being hemolytic anemia, marrow failure and thrombophilia. Chronic hemolysis, failures of the fibrinolytic system, increased leukocyte-derived tissue factor levels in plasma, procoagulant microparticles generated through complement-mediated damage of platelets and venous endothelium are related to the acquired hypercoagulable state. Visceral thrombosis (including hepatic veins and mesenteric veins), cerebrovascular events and pulmonary embolism predict a poor outcome. Thrombosis is also associated with significant morbidity during pregnancy. Depending on the sites of thrombosis, a score-based probability to predict outcome can be assigned. Abdominal vein thromboses account for the majority of morbidity and mortality related to thrombosis, and time-dependent trends suggest that mortality rates tend to decline, with the advent of evolution of therapeutic and diagnostic strategies. In contrast, mortality rates from cerebrovascular events display no significant decline. Prompt diagnosis requires both clinical suspicion and sophisticated imaging techniques, along with multidisciplinary therapeutic intervention. In the eculizumab era, a significant reduction of thrombotic events was observed during therapy, and long-term follow up is needed to establish any benefit in rates and pattern of this complication. However, up to now, only bone marrow transplantation permanently abolishes the coagulation defect.

Yellow fever vaccine induces integrated multilineage and polyfunctional immune responses.

Correlates of immune-mediated protection to most viral and cancer vaccines are still unknown. This impedes the development of novel vaccines to incurable diseases such as HIV and cancer. In this study, we have used functional genomics and polychromatic flow cytometry to define the signature of the immune response to the yellow fever (YF) vaccine 17D (YF17D) in a cohort of 40 volunteers followed for up to 1 yr after vaccination. We show that immunization with YF17D leads to an integrated immune response that includes several effector arms of innate immunity, including complement, the inflammasome, and interferons, as well as adaptive immunity as shown by an early T cell response followed by a brisk and variable B cell response. Development of these responses is preceded, as demonstrated in three independent vaccination trials and in a novel in vitro system of primary immune responses (modular immune in vitro construct [MIMIC] system), by the coordinated up-regulation of transcripts for specific transcription factors, including STAT1, IRF7, and ETS2, which are upstream of the different effector arms of the immune response. These results clearly show that the immune response to a strong vaccine is preceded by coordinated induction of master transcription factors that lead to the development of a broad, polyfunctional, and persistent immune response that integrates all effector cells of the immune system.

Gene Regulation in The Human Immune System. Gene Expression Signatures of Th2 Cell Differentiation, Type 1 Diabetes, and Intrauterine Immune Adaptation

The human immune system is constantly interacting with the surrounding stimuli and microorganisms. However, when directed against self or harmless antigens, these vital defense mechanisms can cause great damage. In addition, the understanding the underlying mechanism of several human diseases caused by aberrant immune cell functions, for instance type 1 diabetes and allergies, remains far from being complete. In this Ph.D. study these questions were addressed using genome-wide transcriptomic analyses. Asthma and allergies are characterized by a hyperactive response of the T helper 2 (Th2) immune cells. In this study, the target genes of the STAT6 transcription factor in naïve human T cells were identified with RNAi for the first time. STAT6 was shown to act as a central activator of the genes expression upon IL-4 signaling, with both direct and indirect effects on Th2 cell transcriptome. The core transcription factor network induced by IL-4 was identified from a kinetic analysis of the transcriptome. Type 1 diabetes is an autoimmune disease influenced by both the genetic susceptibility of an individual and the disease-triggering environmental factors. To improve understanding of the autoimmune processes driving pathogenesis in the prediabetic phase in humans, a unique series of prospective whole-blood RNA samples collected from HLA-susceptible children in the Finnish Type 1 Diabetes Prediction and Prevention (DIPP) study was studied. Changes in different timewindows of the pathogenesis process were identified, and especially the type 1 interferon response was activated early and throughout the preclinical T1D. The hygiene hypothesis states that allergic diseases, and lately also autoimmune diseases, could be prevented by infections and other microbial contacts acquired in early childhood, or even prenatally. To study the effects of the standard of hygiene on the development of neonatal immune system, cord blood samples from children born in Finland (high standard of living), Estonia (rapid economic growth) and Russian Karelia (low standard of living) were compared. Children born in Russian Karelia deviated from Finnish and Estonian children in many aspects of the neonatal immune system, which was developmentally more mature in Karelia, resembling that of older infants. The results of this thesis offer significant new information on the regulatory networks associated with immune-mediated diseases in human. The results will facilitate understanding and further research on the role of the identified target genes and mechanisms driving the allergic inflammation and type 1 diabetes, hopefully leading to a new era of drug development.

Players of Th-cell differentiation and immune dysregulation – focus on GIMAP family genes

The balance of T helper (Th) cell differentiation is the fundamental process that ensures that the immune system functions correctly and effectively. The differentiation is a fine tuned event, the outcome of which is driven by activation of the T-cell in response to recognition of the specific antigen presented. The co-stimulatory signals from the surrounding cytokine milieu help to determine the outcome. An impairment in the differentiation processes may lead to an imbalance in immune responses and lead to immune-mediated pathologies. An over-representation of Th1 type cytokine producing cells leads to tissue-specific inflammation and autoimmunity, and excessive Th2 response is causative for atopy, asthma and allergy. The major factors of Th-cell differentiation and in the related disease mechanisms have been extensively studied, but the fine tuning of these processes by the other factors cannot be discarded. In the work presented in this thesis, the association of T-cell receptor costimulatory molecules CTLA4 and ICOS with autoimmune diabetes were studied. The underlying aspect of the study was to explore the polymorphism in these genes with the different disease rates observed in two geographically close populations. The main focus of this thesis was set on a GTPase of the immunity associated protein (GIMAP) family of small GTPases. GIMAP genes and proteins are differentially regulated during human Th-cell differentiation and have been linked to immune-mediated disorders. GIMAP4 is believed to contribute to the immunological balance via its role in T-cell survival. To elucidate the function of GIMAP4 and GIMAP5 and their role in human immunity, a study combining genetic association in different immunological diseases and complementing functional analyses was conducted. The study revealed interesting connections with the high susceptibility risk genes. In addition, the role of GIMAP4 during Th1-cell differentiation was investigated. A novel function of GIMAP4 in relation to cytokine secretion was discovered. Further assessment of GIMAP4 and GIMAP5 effect for the transcriptomic profile of differentiating Th1-cells revealed new insights for GIMAP4 and GIMAP5 function.