Systolic pressure predicts plasma vasopressin responses to hemorrhage and vena caval constriction in dogs

We have proposed that the reflex increase in arginine vasopressin (AVP) secretion in response to hypovolemia is due to arterial baroreceptor unloading. If arterial pressure is the key to the mechanism, the slope relating plasma AVP to arterial pressure should be the same in response to hemorrhage, a model of true hypovolemia, and in response to thoracic inferior vena caval constriction (IVCC), a model of central hypovolemia. We tested this hypothesis in conscious, chronically instrumented dogs (n = 8). The mean coefficient of determination (r(2)) values obtained from the individual regressions of log AVP onto systolic pressure (SP) and mean arterial pressure (MAP) in response to hemorrhage were 0.953 +/- 0.009 and 0.845 +/- 0.047, respectively. Paired comparisons indicated a significant difference between the means (P < 0.05), hence, SP was used in subsequent analyses. The mean slopes relating the log of plasma AVP to SP in response to hemorrhage and IVCC were -0.034 +/- 0.003 and -0.032 +/- 0.002, respectively, and the means were not significantly different (P = 0.7). The slopes were not altered when the experiments were repeated during acute blockade of cardiac receptors by intrapericardial procaine. Finally, sinoaortic denervation (n = 4) markedly reduced the slope in both the hemorrhage and IVCC treatments. We conclude that baroreceptors monitoring arterial pressure provide the principal reflex control of AVP secretion in response to hypovolemia.     

Arterial baroreceptors control plasma vasopressin responses to graded hypotension in conscious dogs

We studied the role of cardiac and arterial baroreceptors in the reflex control of arginine vasopressin (AVP) and renin secretion during graded hypotension in conscious dogs. The dogs were prepared with Silastic cuffs on the thoracic inferior vena cava and catheters in the pericardial space. Each experiment consisted of a control period followed by four periods of inferior vena caval constriction, during which mean arterial pressure (MAP) was reduced in increments of approximately 10 mmHg. The hormonal responses were measured in five dogs under four treatment conditions: 1) intact, 2) acute cardiac denervation (CD) by intrapericardial infusion of procaine, 3) after sinoaortic denervation (SAD), and 4) during combined SAD+CD. The individual slopes relating MAP to plasma AVP and plasma renin activity (PRA) were used to compare the treatment effects using a 2 x 2 factorial analysis. There was a significant (P < 0.01) effect of SAD on the slope relating plasma AVP to MAP but no effect of CD and no SAD x CD interaction. In contrast, the slope relating PRA and MAP was increased (P < 0.05) by SAD but was not affected by CD. These results support the hypothesis that stimulation of AVP secretion in response to graded hypotension is primarily driven by unloading arterial baroreceptors in the dog.     

Cutting edge: the Wiskott-Aldrich syndrome protein is required for efficient phagocytosis of apoptotic cells

Phagocytosis of apoptotic cells by macrophages and dendritic cells is necessary for clearance of proinflammatory debris and for presentation of viral, tumor, and self Ags. While a number of receptors involved in the cognate recognition of apoptotic cells by phagocytes have been identified, the signaling events that result in internalization remain poorly understood. Here we demonstrate that clearance of apoptotic cells is accompanied by recruitment of the Wiskott-Aldrich syndrome (WAS) protein to the phagocytic cup and that it's absence results in delayed phagocytosis both in vitro and in vivo. Therefore, we propose that WAS protein plays an important and nonredundant role in the safe removal of apoptotic cells and that deficiency contributes significantly to the immune dysregulation of WAS. The efficiency of apoptotic cell clearance may be a key determinant in the suppression of tissue inflammation and prevention of autoimmunity.     

Gene therapy: progress and predictions

The first clinical gene delivery, which involved insertion of a marker gene into lymphocytes from cancer patients, was published 25 years ago. In this review, we describe progress since then in gene therapy. Patients with some inherited single-gene defects can now be treated with their own bone marrow stem cells that have been engineered with a viral vector carrying the missing gene. Patients with inherited retinopathies and haemophilia B can also be treated by local or systemic injection of viral vectors. There are also a number of promising gene therapy approaches for cancer and infectious disease. We predict that the next 25 years will see improvements in safety, efficacy and manufacture of gene delivery vectors and introduction of gene-editing technologies to the clinic. Gene delivery may also prove a cost-effective method for the delivery of biological medicines.     

Low molecular weight catalytic metalloporphyrin antioxidant AEOL 10150 protects lungs from fractionated radiation

The objective of this study was to determine whether administration of a catalytic antioxidant, Mn(III) tetrakis(N,N^′-diethylimidazolium-2-yl) porphyrin, AEOL10150, reduces the severity of long-term lung injury induced by fractionated radiation (RT). Fisher 344 rats were randomized into five groups: RT+AEOL10150 (2.5 mg/kg BID), AEOL10150 (2.5 mg/kg BID) alone, RT+AEOL10150 (5 mg/kg BID), AEOL10150 (5 mg/kg BID) alone and RT alone. Animals received five 8 Gy fractions of RT to the right hemithorax. AEOL10150 was administered 15 min before RT and 8 h later during the period of RT treatment (5 days), followed by subcutaneous injections for 30 days, twice daily. Lung histology at 26 weeks revealed a significant decrease in lung structural damage and collagen deposition in RT+AEOL10150 (5 mg/kg BID) group, in comparison to RT alone. Immunohistochemistry studies revealed a significant reduction in tissue hypoxia (HIF1α, CAIX), angiogenic response (VEGF, CD-31), inflammation (ED-1), oxidative stress (8-OHdG, 3-nitrotyrosine) and fibrosis pathway (TGFβ1, Smad3, p-Smad2/3), in animals receiving RT+AEOL10150 (5 mg/kg BID). Administration of AEOL10150 at 5 mg/kg BID during and after RT results in a significant protective effect from long-term RT-induced lung injury. Low dose (2.5 mg/kg BID) delivery of AEOL10150 has no beneficial radioprotective effects.     

Generation of functional neutrophils from a mouse model of X-linked chronic granulomatous disorder using induced pluripotent stem cells

Murine models of human genetic disorders provide a valuable tool for investigating the scope for application of induced pluripotent stem cells (iPSC). Here we present a proof-of-concept study to demonstrate generation of iPSC from a mouse model of X-linked chronic granulomatous disease (X-CGD), and their successful differentiation into haematopoietic progenitors of the myeloid lineage. We further demonstrate that additive gene transfer using lentiviral vectors encoding gp91(phox) is capable of restoring NADPH-oxidase activity in mature neutrophils derived from X-CGD iPSC. In the longer term, correction of iPSC from human patients with CGD has therapeutic potential not only through generation of transplantable haematopoietic stem cells, but also through production of large numbers of autologous functional neutrophils.     

Development of anti-PAX3 immune responses; a target for cancer immunotherapy

PAX3 is overexpressed in several human cancers and is absent from normal adult human tissues. It is known to have an oncogenic function in human malignancy, and is therefore a promising target for cancer immunotherapy. We screened the murine and human PAX3 amino acid sequences for peptides that bind common MHC class I types, and identified murine GVFINGRPL and human KLTEARVQV sequences. Mice immunised with either a selected PAX3 peptide, or with a PAX3 expressing DNA vector, developed specific anti-PAX3 immune responses that inhibited tumour growth. The intensity of the immune response was significantly enhanced by pulsing of the peptide onto dendritic cells. Anti-PAX3 T cell lines were established from splenocytes of immunised mice. Intravenous administration of anti-PAX3 T cells caused regression of established tumours indicating a promising clinical application for anti-PAX3 immunotherapy. The human peptide stimulated growth of similar T cell lines from peripheral blood of three out of three normal human blood donors. These showed specific cytotoxicity against a range of human PAX3+ and HLA-A2+ cancer cell lines. Moreover, an anti-PAX3 response was detected as a component of the anti-tumour immune response in a patient treated with lysate pulsed dendritic cell vaccination. The ability to generate strong and specific anti PAX3 immune responses from the T cell repertoire in both mice and humans, provides evidence for PAX3 as a promising target for immunotherapy of cancer.