Pathogenesis and classification of eosinophil disorders: a review of recent developments in the field

Eosinophils and their products play an essential role in the pathogenesis of various reactive and neoplastic disorders. Depending on the underlying disease, molecular defect and involved cytokines, hypereosinophilia may develop and may lead to organ damage. In other patients, persistent eosinophilia is accompanied by typical clinical findings, but the causative role and impact of eosinophilia remain uncertain. For patients with eosinophil-mediated organ pathology, early therapeutic intervention with agents reducing eosinophil counts can be effective in limiting or preventing irreversible organ damage. Therefore, it is important to approach eosinophil disorders and related syndromes early by using established criteria, to perform all appropriate staging investigations, and to search for molecular targets of therapy. In this article, we review current concepts in the pathogenesis and evolution of eosinophilia and eosinophil-related organ damage in neoplastic and non-neoplastic conditions. In addition, we discuss classifications of eosinophil disorders and related syndromes as well as diagnostic algorithms and standard treatment for various eosinophil-related disorders.     

Evidence of a Major Reservoir of Non-Malarial Febrile Diseases in Malaria-Endemic Regions of Bangladesh

In malaria-endemic regions any febrile case is likely to be classified as malaria based on presumptive diagnosis largely caused by a lack of diagnostic resources. A district-wide prevalence study assessing etiologies of fever in 659 patients recruited in rural and semi-urban areas of Bandarban district in southeastern Bangladesh revealed high proportions of seropositivity for selected infectious diseases (leptospirosis, typhoid fever) potentially being misdiagnosed as malaria because of similarities in the clinical presentation. In an area with point prevalences of more than 40% for malaria among fever cases, even higher seroprevalence rates of leptospirosis and typhoid fever provide evidence of a major persistent reservoir of these pathogens.     

German guidelines for the sequential medical treatment of rheumatoid arthritis with traditional and biologic disease-modifying antirheumatic drugs

The German Society of Rheumatology approved new German guidelines for the sequential medical treatment of rheumatoid arthritis (RA) based on the European League Against Rheumatism (EULAR) recommendations for the management of RA published in 2010. An update of the EULAR systematic literature research was performed in Medline, Embase, and Cochrane databases. Meta-analyses, controlled trials, cohort studies, and registry data addressing traditional and biologic disease-modifying antirheumatic drugs, glucocorticoids, and treatment strategies published between January 2009 and August 2011 were included. Two reviewers independently evaluated and compared the additional data that had been published after the time limit set by the EULAR recommendations. A national guideline working group developed an adapted set of recommendations. The new German guidelines were accepted by vote using an informal Delphi approach. Twelve recommendations and the resulting updated treatment algorithm were developed and approved as a practical orientation for rheumatologists. These recommendations are based on a successive treatment with traditional and biologic disease-modifying drugs depending on the individual progress of the disease and distinct patient characteristics. The German guidelines have been developed on the basis of the internationally well-recognized EULAR recommendations. In addition, more recent evidence from a systematic literature research was considered. They have been developed and approved by a group of national experts aiming at guidance for rheumatologists to reach best medical practice.     

The KIT D816V expressed allele burden for diagnosis and disease monitoring of systemic mastocytosis

The activating KIT D816V mutation plays a central role in the pathogenesis, diagnosis, and targeted treatment of systemic mastocytosis (SM). For improved and reliable identification of KIT D816V, we have developed an allele-specific quantitative real-time PCR (RQ-PCR) with an enhanced sensitivity of 0.01–0.1 %, which was superior to denaturing high-performance liquid chromatography (0.5–1 %) or conventional sequencing (10–20 %). Overall, KIT D816 mutations were identified in 146/147 (99 %) of patients (D816V, n?=?142; D816H, n?=?2; D816Y, n?=?2) with SM, including indolent SM (ISM, n?=?63, 43 %), smoldering SM (n?=?8, 5 %), SM with associated hematological non-mast cell lineage disease (SM-AHNMD, n?=?16, 11 %), and aggressive SM/mast cell leukemia?±?AHNMD (ASM/MCL, n?=?60, 41 %). If positive in BM, the KIT D816V mutation was found in PB of all patients with advanced SM (SM-AHNMD, ASM, and MCL) and in 46 % (23/50) of patients with ISM. There was a strong correlation between the KIT D816V expressed allele burden (KIT D816V EAB) with results obtained from DNA by genomic allele-specific PCR and also with disease activity (e.g., serum tryptase level), disease subtype (e.g., indolent vs. advanced SM) and survival. In terms of monitoring of residual disease, qualitative and quantitative assessment of KIT D816V and KIT D816V EAB was successfully used for sequential analysis after chemotherapy or allogeneic stem cell transplantation. We therefore conclude that RQ-PCR assays for KIT D816V are useful complimentary tools for diagnosis, disease monitoring, and evaluation of prognosis in patients with SM.     

Large Animal Models for Foamy Virus Vector Gene Therapy

Foamy virus (FV) vectors have shown great promise for hematopoietic stem cell (HSC) gene therapy. Their ability to efficiently deliver transgenes to multi-lineage long-term repopulating cells in large animal models suggests they will be effective for several human hematopoietic diseases. Here, we review FV vector studies in large animal models, including the use of FV vectors with the mutant O⁶-methylguanine-DNA methyltransferase, MGMTP140K to increase the number of genetically modified cells after transplantation. In these studies, FV vectors have mediated efficient gene transfer to polyclonal repopulating cells using short ex vivo transduction protocols designed to minimize the negative effects of ex vivo culture on stem cell engraftment. In this regard, FV vectors appear superior to gammaretroviral vectors, which require longer ex vivo culture to effect efficient transduction. FV vectors have also compared favorably with lentiviral vectors when directly compared in the dog model. FV vectors have corrected leukocyte adhesion deficiency and pyruvate kinase deficiency in the dog large animal model. FV vectors also appear safer than gammaretroviral vectors based on a reduced frequency of integrants near promoters and also near proto-oncogenes in canine repopulating cells. Together, these studies suggest that FV vectors should be highly effective for several human hematopoietic diseases, including those that will require relatively high percentages of gene-modified cells to achieve clinical benefit.     

CD74 indicates microglial activation in experimental diabetic retinopathy and exogenous methylglyoxal mimics the response in normoglycemic retina

Diabetes induces vasoregression, neurodegeneration and glial activation in the retina. Formation of advanced glycation endoproducts (AGEs) is increased in diabetes and contributes to the pathogenesis of diabetic retinopathy. CD74 is increased in activated microglia in a rat model developing both neurodegeneration and vasoregression. In this study, we aimed at investigating whether glucose and major AGE precursor methylglyoxal induce increased CD74 expression in the retina. Expression of CD74 in retinal microglia was analyzed in streptozotocin-diabetic rats by wholemount immunofluorescence. Nondiabetic mice were intravitreally injected with methylglyoxal. Expression of CD74 was studied by retinal wholemount immunofluorescence and quantitative real-time PCR, 48 h after the injection. CD74-positive cells were increased in diabetic 4-month retinas. These cells represented a subpopulation of CD11b-labeled activated microglia and were mainly located in the superficial vascular layer (13.7-fold increase compared to nondiabetic group). Methylglyoxal induced an 9.4-fold increase of CD74-positive cells in the superficial vascular layer and elevated gene expression of CD74 in the mouse retina 2.8-fold. In summary, we identified CD74 as a microglial activation marker in the diabetic retina. Exogenous methylglyoxal mimics the response in normoglycemic retina. This suggests that methylglyoxal is important in mediating microglial activation in the diabetic retina.     

Humans possess two mitochondrial ferredoxins,Fdx1 and Fdx2, with distinct roles in steroidogenesis,heme, and Fe/S cluster biosynthesis

Mammalian adrenodoxin (ferredoxin 1; Fdx1) is essential for the synthesis of various steroid hormones in adrenal glands. As a member of the [2Fe-2S] cluster-containing ferredoxin family, Fdx1 reduces mitochondrial cytochrome P450 enzymes, which then catalyze; e.g., the conversion of cholesterol to pregnenolone, aldosterone, and cortisol. The high protein sequence similarity between Fdx1 and its yeast adrenodoxin homologue (Yah1) suggested that Fdx1, like Yah1, may be involved in the biosynthesis of heme A and Fe/S clusters, two versatile and essential protein cofactors. Our study, employing RNAi technology to deplete human Fdx1, did not confirm this expectation. Instead, we identified a Fdx1-related mitochondrial protein, designated ferredoxin 2 (Fdx2) and found it to be essential for heme A and Fe/S protein biosynthesis. Unlike Fdx1, Fdx2 was unable to efficiently reduce mitochondrial cytochromes P450 and convert steroids, indicating that the two ferredoxin isoforms are highly specific for their substrates in distinct biochemical pathways. Moreover, Fdx2 deficiency had a severe impact, via impaired Fe/S protein biogenesis, on cellular iron homeostasis, leading to increased cellular iron uptake and iron accumulation in mitochondria. We conclude that mammals depend on two distinct mitochondrial ferredoxins for the specific production of either steroid hormones or heme A and Fe/S proteins.