Antigen Processing and Remodeling of the Endosomal Pathway: Requirements for Antigen Cross-Presentation

Cross-presentation of endocytosed antigen as peptide/class I major histocompatibility complex complexes plays a central role in the elicitation of CD8+ T cell clones that mediate anti-viral and anti-tumor immune responses. While it has been clear that there are specific subsets of professional antigen presenting cells capable of antigen cross-presentation, identification of mechanisms involved is still ongoing. Especially amongst dendritic cells (DC), there are specialized subsets that are highly proficient at antigen cross-presentation. We here present a focused survey on the cell biological processes in the endosomal pathway that support antigen cross-presentation. This review highlights DC-intrinsic mechanisms that facilitate the cross-presentation of endocytosed antigen, including receptor-mediated uptake, maturation-induced endosomal sorting of membrane proteins, dynamic remodeling of endosomal structures and cell surface-directed endosomal trafficking. We will conclude with the description of pathogen-induced deviation of endosomal processing, and discuss how immune evasion strategies pertaining endosomal trafficking may preclude antigen cross-presentation

Splenic TFH expansion participates in B-cell differentiation and antiplatelet-antibody production during immune thrombocytopenia

Antiplatelet-antibody-producing B cells play a key role immune thrombocytopenia (ITP) pathogenesis; however, little is known about T-cell dysregulations that support B-cell differentiation. During the past decade, T follicular helper cells (TFHs) have been characterized as the main T-cell subset within secondary lymphoid organs that promotes B-cell differentiation leading to antibody class-switch recombination and secretion. Herein, we characterized TFHs within the spleen of 8 controls and 13 ITP patients. We show that human splenic TFHs are the main producers of interleukin (IL)-21, express CD40 ligand(CD154), and are located within the germinal center of secondary follicles. Compared with controls, splenic TFH frequency is higher in ITP patients and correlates with germinal center and plasma cell percentages that are also increased. In vitro, IL-21 stimulation combined with an anti-CD40 agonist antibody led to the differentiation of splenic B cells into plasma cells and to the secretion of antiplatelet antibodies in ITP patients. Overall, these results point out the involvement of TFH in ITP pathophysiology and the potential interest of IL-21 and CD40 as therapeutic targets in ITP

Polycytemie bij een patiënte met een uterusmyoom

Myomatous erythrocytosis syndrome (MES) is characterised by a combination of polycythaemia, uterus myomatosus and the normalisation of erythrocyte count after hysterectomy. Case description A 58yearold postmenopausal woman was referred to the gynaecologist with symptoms of vaginal blood loss, increased abdominal circumference and pollakiuria. Physical examination indicated her uterus was enlarged to the size of a 24week gestation. Endometrial malignancy was excluded and ultrasound showed a myoma. In consultation with the patient a hysterectomy was planned. Preoperative blood tests showed increased haemoglobin levels (14.2 mmol/l). No indications of polycythaemia vera or secondary polycythaemia were found after which the diagnosis of MES was made. Haemoglobin levels normalised after hysterectomy without any further intervention. Conclusion MES is common, although relatively unknown. Its pathophysiology is most likely based on ectopic production of erythropoietin by leiomyoma tissue. The combination of polycythaemia and uterus myomatosus should alert clinicians to this syndrome, especially as polycythaemia normalises after hysterectomy

Polycytemie bij een patiënte met een uterusmyoom

Myomatous erythrocytosis syndrome (MES) is characterised by a combination of polycythaemia, uterus myomatosus and the normalisation of erythrocyte count after hysterectomy. Case description A 58yearold postmenopausal woman was referred to the gynaecologist with symptoms of vaginal blood loss, increased abdominal circumference and pollakiuria. Physical examination indicated her uterus was enlarged to the size of a 24week gestation. Endometrial malignancy was excluded and ultrasound showed a myoma. In consultation with the patient a hysterectomy was planned. Preoperative blood tests showed increased haemoglobin levels (14.2 mmol/l). No indications of polycythaemia vera or secondary polycythaemia were found after which the diagnosis of MES was made. Haemoglobin levels normalised after hysterectomy without any further intervention. Conclusion MES is common, although relatively unknown. Its pathophysiology is most likely based on ectopic production of erythropoietin by leiomyoma tissue. The combination of polycythaemia and uterus myomatosus should alert clinicians to this syndrome, especially as polycythaemia normalises after hysterectomy

Polycytemie bij een patiënte met een uterusmyoom

Myomatous erythrocytosis syndrome (MES) is characterised by a combination of polycythaemia, uterus myomatosus and the normalisation of erythrocyte count after hysterectomy. Case description A 58yearold postmenopausal woman was referred to the gynaecologist with symptoms of vaginal blood loss, increased abdominal circumference and pollakiuria. Physical examination indicated her uterus was enlarged to the size of a 24week gestation. Endometrial malignancy was excluded and ultrasound showed a myoma. In consultation with the patient a hysterectomy was planned. Preoperative blood tests showed increased haemoglobin levels (14.2 mmol/l). No indications of polycythaemia vera or secondary polycythaemia were found after which the diagnosis of MES was made. Haemoglobin levels normalised after hysterectomy without any further intervention. Conclusion MES is common, although relatively unknown. Its pathophysiology is most likely based on ectopic production of erythropoietin by leiomyoma tissue. The combination of polycythaemia and uterus myomatosus should alert clinicians to this syndrome, especially as polycythaemia normalises after hysterectomy

Effects of sex and estrogen on chicken ductus arteriosus reactivity

Flinsenberg TWH, van der Sterren S, van Cleef ANH, Schuurman MJ, Agren P, Villamor E. Effects of sex and estrogen on chicken ductus arteriosus reactivity. Am J Physiol Regul Integr Comp Physiol 298: R1217-R1224, 2010. First published February 17, 2010; doi: 10.1152/ajpregu.00839.2009.-Sex hormones have an important influence on cardiovascular physiology and pathophysiology and sex differences in vascular reactivity have been widely demonstrated. In the present study we hypothesized 1) the presence of sexual dimorphism in chicken ductus arteriosus (DA) responsiveness to contractile and relaxant stimuli and 2) that estrogens are vasoactive in the chicken DA. In vitro contractions (assessed with a wire myograph) induced by normoxia, KCl, 4-aminopyridine, norepinephrine, phenylephrine, U46619, or endothelin-1, as well as relaxations induced by ACh, sodium nitroprusside, BAY 41-2272, PGE2, isoproterenol, forskolin, Y-27632, and hydroxyfasudil were not significantly different between males and females. The estrogen 17 beta-estradiol elicited concentration-dependent relaxation of KCl-, phenylephrine, and oxygen-induced active tone in male and female chicken DA. The stereoisomer 17 alpha-estradiol showed lesser relaxant effects, and the selective estrogen receptor (ER) agonists 4,4',4 ''-(4-propyl-[H-1]pyrazole-1,3,5-triyl)tris-phenol (ER alpha) and 2,3-bis(4-hydroxyphenyl)-propionitrile (ER alpha) did not show any effect. There were no sex differences in the responses to estrogen. Endothelium removal or the presence of the soluble guanylate cyclase inhibitor ODQ, the K+ channel blockers tetraethylammonium, glibenclamide, and charybdotoxin, or the ER antagonist fulvestrant did not modify 17 beta-estradiol-induced relaxation. CaCl2 (30 mu M-10 mM) induced concentration-dependent contraction in DA rings depolarized by 62.5 mM KCl or stimulated with 21% O-2 in Ca2+-free medium. Preincubation with 17 beta-estradiol or the L-type Ca2+ channel blocker nifedipine produced an inhibition of CaCl2-induced contractions. In conclusion, there are no sex-related differences in chicken DA reactivity. The estrogen 17 beta-estradiol induces an endothelium-independent relaxation of chicken DA that is not mediated by ER activation. This relaxant effect is, at least partially, due to inhibition of Ca2+ entry from extracellular space

Generation of a cord blood-derived Wilms Tumor 1 dendritic cell vaccine for AML patients treated with allogeneic cord blood transplantation

The poor survival rates of refractory/relapsed acute myeloid leukemia (AML) patients after haematopoietic cell transplantation (HCT) requires the development of additional immune therapeutic strategies. As the elicitation of tumor-antigen specific cytotoxic T lymphocytes (CTLs) is associated with reduced relapses and enhanced survival, enhanced priming of these CTLs using an anti-AML vaccine may result in long-term immunity against AML. Cord blood (CB), as allogeneic HCT source, may provide a unique setting for such post-HCT vaccination, considering its enhanced graft-versus-leukemia (GvL) effects and population of highly responsive naïve T cells. It is our goal to develop a powerful and safe immune therapeutic strategy composed of CB-HCT followed by vaccination with CB CD34(+)-derived dendritic cells (DCs) presenting the oncoprotein Wilms Tumor-1 (WT1), which is expressed in AML-blasts in the majority of patients. Here, we describe the optimization of a clinically applicable DC culture protocol. This two-step protocol consisting of an expansion phase followed by the differentiation toward DCs, enables us to generate sufficient cord blood-derived DCs (CBDCs) in the clinical setting. At the end of the culture, the CBDCs exhibit a mature surface phenotype, are able to migrate, express tumor antigen (WT1) after electroporation with mRNA encoding the full-length WT1 protein, and stimulate WT1-specific T cells