André-Pascal Sappino

The inducing role of tumor necrosis factor in the development of bactericidal granulomas during BCG infection

Granuloma formation in the liver of mice infected with BCG coincides with local TNF synthesis. Injection of rabbit anti-TNF antibody, after 1 or 2 weeks of infection, dramatically interferes with the development of granulomas (both in number and size, large epithelioid cells failing to appear) and subsequent mycobacterial elimination. Furthermore, fully developed BCG granulomas, after 3 weeks of infection, rapidly regress after anti-TNF treatment. Antibody treatment also prevents or suppresses accumulation of TNF mRNA and protein, which resumes after disappearance of the antibody. Peritoneal macrophages exposed to TNF transiently accumulate TNF mRNA, and show an enhanced increase in TNF mRNA in response to gamma interferon. We propose that TNF released from macrophages in the microenvironment of developing granulomas is involved in a process of autoamplification: acting in an autocrine or paracrine way, it enhances its own synthesis and release, thus favoring further macrophage accumulation and differentiation leading to bacterial elimination.

The plasminogen activator/plasmin system.

proteases and inhibitors has been shown to be under the control of hormones and growth factors. Plasminogen activators (PAs) and their inhibitors (PAIs) are thought to be key participants in the balance ofproteolytic and antiproteolytic activities that regulates matrix turnover. This article summarizes the evidence that supports this contention, discusses the role ofPAspecific cell surface binding sites, and also draws attention to a number of instances in which the presence ofPAs cannot be reconciled with an exclusive function in ECM degradation.

Undertreatment Strongly Decreases Prognosis of Breast Cancer in Elderly Women

PURPOSE No consensus exists on therapy of elderly cancer patients. Treatments are influenced by unclear standards and are usually less aggressive. This study aims to evaluate determinants and effect of treatment choice on breast cancer prognosis among elderly patients. PATIENTS AND METHODS We reviewed clinical files of 407 breast cancer patients aged >/= 80 years recorded at the Geneva Cancer Registry between 1989 and 1999. Patient and tumor characteristics, general health status, comorbidity, treatment, and cause of death were considered. We evaluated determinants of treatment by logistic regression and effect of treatment on mortality by Cox model, accounting for prognostic factors. RESULTS Age was independently linked to the type of treatment. Overall, 12% of women (n = 48) had no treatment, 32% (n = 132) received tamoxifen only, 7% (n = 28) had breast-conserving surgery only, 33% (n = 133) had mastectomy, 14% (n = 57) had breast-conserving surgery plus adjuvant therapy, and 2% (n = 9) received miscellaneous treatments. Five-year specific breast cancer survival was 46%, 51%, 82%, and 90% for women with no treatment, tamoxifen alone, mastectomy, and breast-conserving surgery plus adjuvant treatment, respectively. Compared with the nontreated group, the adjusted hazard ratio of breast cancer mortality was 0.4 (95% CI, 0.2 to 0.7) for tamoxifen alone, 0.4 (95% CI, 0.1 to 1.4) for breast-conserving surgery alone, 0.2 (95% CI, 0.1 to 0.7) for mastectomy, and 0.1 (95% CI, 0.03 to 0.4) for breast-conserving surgery plus adjuvant treatment. CONCLUSION Half of elderly patients with breast cancer are undertreated, with strongly decreased specific survival as a consequence. Treatments need to be adapted to the patients health status, but also should offer the best chance of cure.

Extracellular proteolysis in the adult murine brain.

Plasminogen activators are important mediators of extracellular metabolism. In the nervous system, plasminogen activators are thought to be involved in the remodeling events required for cell migration during development and regeneration. We have now explored the expression of the plasminogen activator/plasmin system in the adult murine central nervous system. Tissue-type plasminogen activator is synthesized by neurons of most brain regions, while prominent tissue-type plasminogen activator-catalyzed proteolysis is restricted to discrete areas, in particular within the hippocampus and hypothalamus. Our observations indicate that tissue-type plasminogen activator-catalyzed proteolysis in neural tissues is not limited to ontogeny, but may also contribute to adult central nervous system physiology, for instance by influencing neuronal plasticity and synaptic reorganization. The identification of an extracellular proteolytic system active in the adult central nervous system may also help gain insights into the pathogeny of neurodegenerative disorders associated with extracellular protein deposition.

Human clusterin gene expression is confined to surviving cells during in vitro programmed cell death.

Clusterin is a serum glycoprotein endowed with cell aggregating, complement inhibitory, and lipid binding properties, and is also considered as a specific marker of dying cells, its expression being increased in various tissues undergoing programmed cell death (PCD). However, no study has so far directly shown that cells expressing clusterin in these tissues are actually apoptotic as defined by morphological and biochemical criteria. We have studied cellular clusterin gene expression in vitro using three different models of PCD: (a) ultraviolet B (UV-B) irradiation of human U937, HeLa, and A431 cell lines, (b) in vitro aging of human peripheral blood neutrophils (PMNs), and (c) dexamethasone-induced cell death of the human lymphoblastoid cell line CEM-C7. In all three models, the classical morphological and biochemical features of PCD observed did not correlate with an increase, but with either a marked decrease or an absence of clusterin gene expression as assessed by Northern blot analysis. In situ hybridization of U937 and A431 cells after UV-B irradiation revealed, in addition, that only morphologically normal cells that are surviving continue to express the clusterin gene. Our results demonstrate that in the human myeloid, lymphoid, and epithelial cell types studied, clusterin gene expression is not a prerequisite to their death by apoptosis. In addition, and most interestingly, in situ hybridization of U937 and A431 cells revealed that only surviving cells express the clusterin gene after the induction of PCD, thus providing novel evidence suggesting that clusterin may be associated with cell survival within tissues regressing as a consequence of PCD.

Sites of synthesis of urokinase and tissue-type plasminogen activators in the murine kidney

Kidneys have long been recognized as a major source of plasminogen activators (PAs). However, neither the sites of synthesis of the enzymes nor their role in renal function have been elucidated. By the combined use of zymographies on tissue sections and in situ hybridizations, we have explored the cellular distribution of urokinase-type (u-PA) and tissue-type (t-PA) plasminogen activators and of their mRNAs in developing and adult mouse kidneys. In 17.5-d old embryos, renal tubules synthesize u-PA, while S-shaped bodies produce t-PA. In the adult kidney, u-PA is synthesized and released in urine by the epithelial cells lining the straight parts of both proximal and distal tubules. In contrast, t-PA is produced by glomerular cells and by epithelial cells lining the distal part of collecting ducts. The precise segmental distribution of PAs suggests that both enzymes may be implicated in the maintenance of tubular patency, by catalyzing extracellular proteolysis to prevent or circumvent protein precipitation.

Plasminogen activator inhibitor-1 in acute hyperoxic mouse lung injury

Hyperoxia-induced lung disease is associated with prominent intraalveolar fibrin deposition. Fibrin turnover is tightly regulated by the concerted action of proteases and antiproteases, and inhibition of plasmin-mediated proteolysis could account for fibrin accumulation in lung alveoli. We show here that lungs of mice exposed to hyperoxia overproduce plasminogen activator inhibitor-1 (PAI-1), and that PAI-1 upregulation impairs fibrinolytic activity in the alveolar compartment. To explore whether increased PAI-1 production is a causal or only a correlative event for impaired intraalveolar fibrinolysis and the development of hyaline membrane disease, we studied mice genetically deficient in PAI-1. We found that these mice fail to develop intraalveolar fibrin deposits in response to hyperoxia and that they are more resistant to the lethal effects of hyperoxic stress. These observations provide clear and novel evidence for the pathogenic contribution of PAI-1 in the development of hyaline membrane disease. They identify PAI-1 as a major deleterious mediator of hyperoxic lung injury.

Locally applied GM-CSF induces the accumulation of α-smooth muscle act in containing myofibroblasts

SummaryWe have examined the histological and cytoskeletal changes in rat connective tissues induced by subcutaneous perfusion with cytokines. Granulocyte macrophage-colony stimulating factor (GM-CSF), tumor necrosis factor-α (TNF-α), interleukin-1-α (IL-l-α), transforming growth factor-β (TGF-β) and platelet-derived growth factor (PDGF) produced a significant fibroblast accumulation, neovascular development and a weak to moderate leukocyte infiltration, while interleukin-2 (IL-2) and γ-interferon (γ-IFN) induced intense mononucleated leukocyte infiltration. Immunofluorescence staining showed that accumulated fibroblastic cells were positive for α-smooth muscle (SM) actin (but negative for the desmin and muscle myosin) only in GM-CSF-treated tissues. Electron microscopic examination established that a signifikant proportion of fibroblastic cell in GM-CSF-, IL-l-α- or TGF-β-treated animals were typical myofibroblasts. Only in GM-CSF-treated animals did microfilament bundles of myofibroblasts contain α-SM actin, when examined by immuno electron microscopy. Our results suggest that locally applied cytokines induce the formation of distinct granulation tissues. In particular, GM-CSF stimulates a-SM actin synthesis in myofibroblasts, illustrating an unexpected extra-hematopoietic in vivo effect of this factor.

ATM gene and lymphoid malignancies.

Inherited biallelic mutations of the ATM (ataxia-telangiectasia mutated) gene cause ataxia-telangiectasia, a rare autosomal recessive disorder associated with a high incidence of childhood leukaemias and lymphomas, suggesting that ATM gene alterations may be involved in lymphomagenesis. Loss of heterozygosity at 11q22–23 (location of the ATM gene) is a frequent event in sporadic lymphoid tumours, and several studies have reported a high prevalence of ATM gene alterations in diverse sporadic lymphoproliferative disorders, adding evidence to the postulated contribution of ATM in the pathogenesis of these tumours. This mini-review will summarize the recently published data concerning the ATM gene in sporadic lymphoid malignancies and will discuss the apparent paradox between the predominance of nonsense mutations observed in patient with ataxia-telangiectasia and the high proportion of missense alterations found in sporadic lymphoid tumours.

Elevated levels of angiogenic cytokines in the plasma of cancer patients

Although in the normal healthy organism angiogenesis is a tightly regulated process, under a variety of circumstances it may contribute to disease states. These include the growth of solid tumors, the hematogenous spread of tumor cells and the growth of metastasis. Our aim was to measure the levels of 5 angiogenic cytokines in the plasma of patients with a variety of cancers, to establish a plasmatic angiogenic profile. We prospectively obtained blood samples in citrated tubes from 40 healthy individuals and 75 patients with a variety of solid tumors. Patients who had received any form of treatment in the preceeding 6 months were excluded from the study. Plasma levels of the following 5 cytokines were determined by ELISA: vascular endothelial growth factor (VEGF), hepatocyte growth factor (HGF), basic fibroblast growth factor, transforming growth factor‐β and tumor necrosis factor‐α. In some cases, additional samples were taken 4 and 15 days after surgical removal of the tumor. Our findings demonstrate, that firstly, compared to the tumor group VEGF was almost always undetectable or present at very low levels in healthy individuals; secondly, a threshold value for HGF was found to exist between the 2 groups (healthy vs. tumor); and thirdly, there was a clear relationship between plasma levels of VEGF and HGF and extension of disease (i.e., without or with metastases). The timing of blood sampling in the post‐operative period was found to be critical, particularly with regard to VEGF and HGF. The existence of a systemic angiogenic profile in the plasma of cancer patients may be useful as a diagnostic and prognostic tool and may help in the future to monitor the responses of individual patients to anti‐tumor and, particularly, anti‐angiogenic therapy. Int. J. Cancer 85:40–45, 2000.