Thymocyte expression of cathepsin L is essential for NKT cell development

CD1d antigen presentation to natural killer T (NKT) cells expressing the semi-invariant T cell receptor V(alpha)14J(alpha)18 requires CD1d trafficking through endosomal compartments; however, the endosomal events remain undefined. We show that mice lacking the endosomal protease cathepsin L (catL) have greatly reduced numbers of V(alpha)14(+)NK1.1(+) T cells. In addition, catL expression in thymocytes is critical not only for selection of these cells in vivo but also for stimulation of V(alpha)14(+)NK1.1(+) T cells in vitro. CD1d cell-surface expression and intracellular localization appear normal in catL-deficient thymocytes, as does the lysosomal morphology; this implies a specific role for catL in regulating presentation of natural CD1d ligands mediating V(alpha)14(+)NK1.1(+) T cell selection. These data implicate lysosomal proteases as key regulators of not only classical major histocompatibility complex class II antigen presentation but also nonclassical CD1d presentation.     

The seroepidemiology of human T-lymphotropic viruses: types I and II in Europe: a prospective study of pregnant women

BACKGROUND: Up to 20 million persons are infected with the human retroviruses human T-lymphotropic virus (HTLV)-I and HTLV-II globally. Most data on the seroprevalence of HTLV-I and HTLV-II in Europe are from studies of low-risk blood donors or high-risk injection drug users (IDUs). Little is known about the general population. METHODS: A prospective anonymous study of HTLV-I and HTLV-II seroprevalence among 234,078 pregnant women in Belgium, France, Germany, Italy, Portugal, Spain, and the United Kingdom was conducted. Maternal antibody status was determined by standard methods using sera obtained for routine antenatal infection screens or eluted from infant heel prick dried blood spots obtained for routine neonatal metabolic screens. RESULTS: Anti-HTLV-I/II antibodies were detected and confirmed in 96 pregnant women (4.4 per 10,000, 95% confidence interval [CI]: 3.5-5.2). Of these, 73 were anti-HTLV-I, 17 were anti-HTLV-II, and 6 were specifically anti-HTLV but untyped. The seroprevalence ranged from 0.7 per 10,000 in Germany to 11.5 per 10,000 in France. CONCLUSIONS: Pregnant women better reflect the general population than blood donors or IDUs. The seroprevalence of HTLV-I and HTLV-II in Western Europe is 6-fold higher among pregnant women (4.4 per 10,000) than among blood donors (0.07 per 10,000). These data provide a robust baseline against which changes in HTLV-I and HTLV-II seroprevalence in Europe can be measured.     

Study of the protective effects of hyperimmune immunoglobulins G and M against endotoxin in mice and rats

We prepared solutions of human IgM and IgG to various lipopolysaccharide (LPS) species. These were then tested, along with solutions of non-LPS specific human IgG or IgM, for their ability to confer passive immunity against experimental endotoxemia in two animal models. The immunoglobulins were first tested for an effect on the lethality induced by seven different LPSs in actinomycin-D sensitized mice, or by three different bacteria in normal mice. When the immunoglobulins were administered 1 h before challenge, a small protective effect was observed. This protection was dependent upon both the anti-LPS agent, the chemical composition of the LPS, or the strain of Gram-negative bacteria used for injection. The anti-LPS IgM and IgG preparations reduced the mortality induced by Escherichia coli but not by Serratia marcescens or Klebsiella pneumoniae, indicating protection by strain-specific antibodies. When the antibodies were preincubated with LPS or bacteria for 30 min before administration, almost complete protection was seen. The influence of these immunoglobulin preparations or of human albumin (as a control) on the hypotensive and vascular-permeabilizing effects of LPS in rats was then studied. A dose-dependent inhibitory effect was observed with IgG preparations and albumin. At 200 mg/kg, anti-LPS IgG reduced the effects of LPS, while at 400 mg/kg, both anti-LPS and normal IgG preparations showed protection, as did human albumin used at the same dose. The IgM-enriched preparation worsened the initial hypotensive phase after LPS, whereas the anti-LPS IgM significantly reduced the second phase of the hypotension, but only at the largest dose of 400 mg/kg. In this second model using the rat, a clear difference between the activity of IgG and IgM was thus observed. We conclude that pretreatment with human immunoglobulins from large plasma pools modestly, but significantly, attenuated the effects of murine and rat Gram-negative sepsis, but that protection was incomplete. Our results suggest that single regimen intervention strategies may not be sufficient to influence the course of the disease. Received: 12 December 1998     

BK virus antibody titers and intensity of infections after renal transplantation

BACKGROUND: The mean urine BK viral load in kidney transplant recipients increases with the intensity of infection as the infection progresses from transient viruria to sustained viremia. OBJECTIVES: This study investigated whether the intensity of infection is associated with the humoral immune response. STUDY DESIGN: We measured BKV-specific IgG antibody titers in stored samples obtained serially over a 1-year period from 70 kidney transplant recipients with BKV infection and 17 control recipients without active BKV infection. RESULTS: The mean pre-transplant BKV antibody level was lower in recipients who developed viremia than the mean level in those who never developed viremia (p=0.004). Mean antibody titers in recipients who never showed evidence of active BKV infection rose slightly after transplant despite immunosuppression. The magnitude of the rise in the mean antibody titers in recipients who developed active BKV infection correlated with the intensity of infection (p<0.001). CONCLUSIONS: The mean antibody level increased in accordance with the intensity of the infection post-transplant. Pre-transplant seropositivity did not protect against sustained viremia and the antibody response was not associated with clearance of the virus.     

Congenital stationary night blindness: report of an autosomal recessive family and linkage analysis

Congenital stationary night blindness (CSNB) is a group of rare, non-progressive conditions of the retina characterized by abnormal rod function causing impaired night vision. Among them, the Schubert-Bornschein subgroup, itself divided into a complete and an incomplete form, is characterized by a specific electrophysiological pattern. Complete, Schubert-Bornschein CSNB is usually transmitted as a monogenic trait, and most familial cases result from mutations of the NYX gene located on the X chromosome. We report a very rare family with consanguineous, first-cousin parents, where a son and a daughter are affected with this condition, indicating autosomal recessive inheritance. As the family was too small for genome-wide linkage, we considered several candidate loci, including the sidekick SDK1 and SDK2 genes. The latter determine lamina-specific connectivity in the retina, a histological substrate of the ON pathway implicated in complete, Schubert-Bornschein CSNB. Although linkage was excluded in our family, observations like the present one may lead to the identification of a new molecular cause for this condition.     

Enhanced viral clearance in interleukin-18 gene-deficient mice after pulmonary infection with influenza A virus

T helper 1 driven immune responses facilitate host defence during viral infections. Because interleukin-18 (IL-18) mediates T helper 1 driven immune responses, and since mature IL-18 is up-regulated in human macrophages after influenza virus infection in vitro, it has been suggested that IL-18 plays an important role in the immune response to influenza. To determine the role of IL-18 in respiratory tract infection with influenza, IL-18 gene-deficient (IL-18(-/-)) and normal wildtype mice were intranasally inoculated with influenza A virus. Influenza resulted in an increase in constitutively expressed IL-18 in the lungs of wildtype mice. The clearance of influenza A was inhibited by IL-18, as indicated by reduced viral loads on day 8 and day 12 after infection in IL-18(-/-) mice. This enhanced viral clearance correlated with increased CD4(+) T-cell activation in the lungs as reflected by CD69 expression on the cell surface. Surprisingly, interferon-gamma (IFN-gamma) levels were similar in the lungs of IL-18(-/-) mice and wildtype mice. Intracellular IFN-gamma staining revealed similar expression levels in lung-derived natural killer cells, CD4(+) and CD8(+) T cells, indicating that IFN-gamma production is IL-18-independent during influenza virus infection. Tumour necrosis factor-alpha production by CD4(+) T cells was significantly lower in IL-18(-/-) mice than in wildtype mice. Our data indicate that endogenous IL-18 impairs viral clearance during influenza A infection.     

Leaf trajectory verification during dynamic intensity modulated radiotherapy using an amorphous silicon flat panel imager

An independent verification of the leaf trajectories during each treatment fraction improves the safety of IMRT delivery. In order to verify dynamic IMRT with an electronic portal imaging device (EPID), the EPID response should be accurate and fast such that the effect of motion blurring on the detected moving field edge position is limited. In the past, it was shown that the errors in the detected position of a moving field edge determined by a scanning liquid-filled ionization chamber (SLIC) EPID are negligible in clinical practice. Furthermore, a method for leaf trajectory verification during dynamic IMRT was successfully applied using such an EPID. EPIDs based on amorphous silicon (a-Si) arrays are now widely available. Such a-Si flat panel imagers (FPIs) produce portal images with superior image quality compared to other portal imaging systems, but they have not yet been used for leaf trajectory verification during dynamic IMRT. The aim of this study is to quantify the effect of motion distortion and motion blurring on the detection accuracy of a moving field edge for an Elekta iViewGT a-Si FPI and to investigate its applicability for the leaf trajectory verification during dynamic IMRT. We found that the detection error for a moving field edge to be smaller than 0.025 cm at a speed of 0.8 cm/s. Hence, the effect of motion blurring on the detection accuracy of a moving field edge is negligible in clinical practice. Furthermore, the a-Si FPI was successfully applied for the verification of dynamic IMRT. The verification method revealed a delay in the control system of the experimental DMLC that was also found using a SLIC EPID, resulting in leaf positional errors of 0.7 cm at a leaf speed of 0.8 cm/s.     

Keratinocyte growth factor expression by fibroblasts in pulmonary fibrosis: poor response to interleukin-1beta

Keratinocyte growth factor (KGF) is secreted by fibroblasts and protects from pulmonary fibrosis in animal models. Interleukin (IL)-1beta is the most potent inducer of KGF in fibroblasts, acting through the c-Jun pathway. We evaluated in vitro KGF production by human lung fibroblasts from patients with idiopathic pulmonary fibrosis (IPF, n = 10) and from control subjects (n = 7) at baseline and after IL-1beta stimulation. Basal KGF secretion by IPF fibroblasts was similar to controls. In fibroblasts from control subjects, IL-1beta increased c-Jun expression, c-Jun activation, and KGF secretion. SP600125, a specific c-Jun N-terminal kinase (JNK) inhibitor, inhibited the effect of IL-1beta. By contrast, in IPF fibroblasts, IL-1beta did not increase c-Jun expression and c-Jun activation, and weakly increased KGF secretion, whereas SP600125 had no effect. IL-1beta similarly increased JunB expression in fibroblasts from patients with IPF and control subjects. Total JNK content was not different in either unstimulated or IL-1beta-stimulated IPF and control fibroblasts. IL-1beta increased phosphorylated JNK in control and IPF fibroblasts, but this increase was weaker and heterogeneous in IPF. Altogether, our results demonstrate a dysregulation of KGF secretion by IPF fibroblasts. The weak response to IL-1beta is associated with a defect of c-Jun expression and activation and a defect of JNK activation.     

Peroxisome proliferator-activated receptor gamma is expressed in airways and inhibits features of airway remodeling in a mouse asthma model

BACKGROUND: Allergic asthma is associated with persistent functional and structural changes in the airways and involves many different cell types. Peroxisome proliferator-activated receptor gamma (PPAR-gamma), a member of the nuclear hormone receptor superfamily, is predominantly expressed in adipose tissue and plays a major role in regulating adipocyte differentiation and glucose metabolism. Recently, PPAR-gamma has been shown to play an important role in the control of inflammatory responses, including within the lung, acting on both immune and nonimmune cells. OBJECTIVE: Our aim was to assess the anti-inflammatory potential of a PPAR-gamma agonist locally delivered by means of nebulization. METHODS: We used a mouse model of asthma induced by sensitization and airway challenge with ovalbumin. Ciglitazone, a PPAR-gamma agonist, was administered by means of nebulization alone at the time of antigen challenge or by means of gavage and nebulization. Treatments with both ciglitazone and GW9662, a specific antagonist, were also performed to verify that ciglitazone's effects were mediated through PPAR-gamma activation. RESULTS: Our results show that PPAR-gamma is mainly expressed in airway epithelium on antigen sensitization. Treatment with ciglitazone reduced PPAR-gamma levels in the lung, whereas combined treatment with GW9662 abrogated this inhibition. Importantly, nebulization with ciglitazone decreased airway hyperresponsiveness, basement membrane thickness, mucus production, collagen deposition, and TGF-beta synthesis. A significant correlation was also found between airway hyperresponsiveness, basement membrane thickness, and TGF-beta levels. CONCLUSION: These results demonstrate that inhaled agonistic ligands of PPAR-gamma might have new therapeutic potential for airway asthmatic inflammation.