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Biomedical subjects

M Sironi

Publications and source records attributed to M Sironi.

At least 55 records · Page 3Linked to original sources
PubMed1999

Glucocorticoids affect human dendritic cell differentiation and maturation.

Because dendritic cells (DC) play a major role in the initiation of T cell-mediated immunity, we studied the effects of glucocorticoids, well-known inhibitors of the immune and inflammatory response, on the differentiation and maturation of human DC. DC were differentiated from human monocytes by culture with GM-CSF and IL-4 for 7 days with and without dexamethasone (Dex). Cells treated with Dex (10-8 M) (Dex-DC) developed a characteristic dendritic morphology; however, membrane phenotype analysis demonstrated that they were not fully differentiated. Dex-DC expressed low levels of CD1a and, unlike untreated cells, high levels of CD14 and CD16. Molecules involved in Ag presentation (CD40, CD86, CD54) were also impaired. In contrast, molecules involved in Ag uptake (mannose receptor, CD32) and cell adhesion (CD11/CD18, CD54) were up-regulated. After exposure to TNF-alpha or CD40 ligand, Dex-DC expressed lower levels of CD83 and CD86 than untreated cells. Dex-DC showed a higher endocytic activity, a lower APC function, and a lower capacity to secrete cytokines than untreated cells. Overall, these results indicate that DC differentiated in the presence of Dex are at a more immature stage. Moreover, Dex also partially blocked terminal maturation of already differentiated DC. In conclusion, our data suggest that glucocorticoids may act at the very first step of the immune response by modulating DC differentiation, maturation, and function.

Antigen Presentation↗
PubMed1999

Occult sporadic medullary microcarcinoma with lymph node metastases.

A sporadic form of medullary occult microcarcinoma was cytologically diagnosed, by fine-needle aspiration biopsy (FNAB), on metastatic cervical lymph nodes. The cytologic specimens were partially smeared and partially zinc-formalin-fixed, so that a microinclusion clot for immunohistochemical studies would be possible. The reactivity to calcitonin of neoplastic cells obtained from metastatic cervical lymph nodes supported the search for a thyroid tumor, which only a careful echographic study revealed. Under sonographic guidance, FNAB on a 0.5-cm hypoechoid nodule was performed. The smears were diagnostic of medullary carcinoma. A total thyroidectomy with node dissection was made. Diagn. Cytopathol. 1999;21:203-206.

Biopsy, Needle↗
PubMed1999

Characterization of type II intracellular IL-1 receptor antagonist (IL-1ra3): a depot IL-1ra.

Three molecular forms of the IL-1 receptor antagonist (IL-1ra) have been identified and cloned. Secreted IL-1ra (sIL-1ra or IL-1ra1) contains a classical leader peptide giving a released mature protein. Two intracellular isoforms, icIL-1ra type I (IL-1ra2) and icIL-1ra type II (IL-1ra3), have no leader sequence, thus predicting that these proteins remain intracellular. In an effort to define its biological role, we structurally and functionally characterized IL-1ra3. Endogenous immunoreactive IL-1ra3 was detected in a variety of inflammatory cells and tissues. We used a gene transfer strategy to explore the possible intracellular functions of IL-1ra3 (and IL-1ra2) and the cell-associated agonist IL-1alpha. The intracellular IL-1ra3 isoform, as well as IL-1ra2, does not block the action of exogenous and endogenous IL-1 under these conditions. Intact IL-1ra3 was released from the cells killed by NK effectors. The intracellular isoforms may represent a reservoir of IL-1ra, released upon cell death, whose function is to limit the pro-inflammatory action of cell debris.

Animals↗
PubMed1999

Activity of alpha-secretase as the common final effector of protein kinase C-dependent and -independent modulation of amyloid precursor protein metabolism.

The metabolic fate of the amyloid precursor protein (APP) is one of the key factors in the pathogenesis of Alzheimer's disease (AD). A complex cellular mechanism regulates the rate at which the precursor is cleaved by alpha-secretase and released as soluble protein in the extracellular space. We show here that alpha-secretase constitutes the common final effector of several independent means of stimulation of soluble APP (sAPP) release. The release of sAPP by alpha-secretase resembles that of several other membrane-bound proteins with soluble counterparts, a process that is sensitive to matrix metalloprotease inhibitors. The hydroxamic acid-based compound KD-IX-73-4 inhibits phorbol ester-mediated sAPP release from COS cells with an IC50 of 8 microM, consistent with previous data for the same compound against leukocyte L-selectin shedding. Beyond direct protein kinase C (PKC) activation we show that KD-IX-73-4 inhibits also receptor-mediated sAPP release induced by carbachol in SH-SY5Y cells and by bradykinin in human skin fibroblasts, with the latter being a PKC-independent mechanism. Altogether these data suggest that all pharmacological means of stimulating sAPP release converge to a hydroxamic acid-based inhibitor-sensitive proteolytic enzyme. Moreover, because KD-IX-73-4 was effective in the inhibition of stimulated but not constitutive sAPP release, these data suggest the existence of different enzymes regulating the two metabolic pathways leading to sAPP secretion.

Amyloid Precursor Protein Secretases↗
PubMed1999

A small synthetic molecule capable of preferentially inhibiting the production of the CC chemokine monocyte chemotactic protein-1.

Blocking chemokine production or action is a major target for pharmacological intervention in different human diseases. Bindarit (2-methyl-2-[[1-(phenylmethyl)-1H-indazol-3yl]methoxy]propan oic acid) dose-dependently inhibited MCP-1 and TNF-alpha production induced in vitro in monocytes by LPS and Candida albicans. It did not affect the production of the cytokines IL-1, IL-6, or the chemokines IL-8, MIP-1alpha and RANTES. In the air pouch model in mice, oral treatment reduced monocyte recruitment and local MCP-1 production, induced by carrageenan or IL-1 injection. In NZB/W mice, a model of lupus nephritis, oral treatment prolonged survival and delayed the onset of proteinuria. The results presented here show that bindarit is a preferential inhibitor of the production of MCP-1 in vitro and in vivo and suggest that its beneficial effects in models of joint and kidney inflammation are related to its anti-MCP-1 action. It is therefore possible to selectively and differentially regulate chemokines by targeting their production with small synthetic molecules.

Animals↗
PubMed1999

[Nephrogenic adenoma of the bladder. Morphological and immunophenotypic study with particular attention to differential diagnosis].

BACKGROUND: Nephrogenic Adenoma (NA) is a rare lesion of the urinary tract, considered a metaplastic response to chronic inflammation, trauma or immunosuppression. METHODS AND RESULTS: We report two cases of NA arising in the urinary bladder of patients with previous history of recurrent urinary tract infections due to neuropsychiatric disease. Pathological examination of the lesions, resected by transurethral (TUR) management, revealed a papillary proliferation of tubules and cysts lined by cuboidal to low-columnar cells without atypia. Immunohistochemistry showed positivity for Cam 5.2, CK7 and EMA. MIB 1 count demonstrated a positivity in 12/200 cells in case 1 and < 2/200 in case 2. No expression of nuclear p53 was evident. CONCLUSION: NA is a benign unusual neoplasm which might be misdiagnosed as clear cell adenocarcinoma of the bladder or prostatic adenocarcinoma. Its recognition is important because it is a benign lesion cured by a conservative resection and no additional therapy is generally required.

Adenocarcinoma↗
PubMed1999

Pure yolk sac tumors in genital and extragenital sites: study on three pedriatic cases, with cytological findings on two.

Cytopathological findings on three pedriatic gonadic-extragonadic pure yolk sac tumor are reported: the highly variable histological patterns (reticular, solid, festooning or pseudopapillary, polyvesicular vitelline), reflecting differentiation towards extraembryonic yolk sac structures, are not appreciated in cytologic samples. Since the tumor's cytologic spectrum is very broad, the most diagnostic differential difficulty with yolk sac tumor is adenocarcinoma. The presence of intracellular and extracellular hyaline globules, that are periodic acid-Schiff stain (PAS) positive and diastase resistant and correspond to alpha-fetoprotein production, alpha-fetoprotein positivity of the neoplastic cells; showing nuclear pleomorphism and vacuolated "bubbly" cytoplasm are the most consistent cytologic hallmarks of this neoplasm, which diagnosis would be confirmed by histologic, immunocytochemical and clinical findings.

Adenocarcinoma↗
PubMed1998

Insertion of two independent enhancers in the long terminal repeat of a self-inactivating vector results in high-titer retroviral vectors with tissue-specific expression.

The use of retroviral vectors (RVs) derived from the murine oncoretroviruses for gene therapy is associated with the risk of malignant transformation of infected cells and ectopic expression of the proteins of interest. Targeting retroviral vectors to specific tissues would increase their safety and clinical applicability. To explore the potential of targeting vector expression to skeletal muscle, the murine leukemia virus broad transcriptional tropism was modified by substituting the viral promoter and/or enhancer with a transcriptional cassette containing the human T cell leukemia virus type I Tax-responsive element and the minimal muscle creatine kinase enhancer and promoter. The resulting retroviral vectors could be transcriptionally trans-activated by tax. In the absence of Tax, however, the viruses showed muscle-specific expression. Trans-complementing packaging and indicator cells stably expressing Tax were used to isolate high-titer producer cell clones (10(6) CFU/ml). In vitro, the levels of expression of these RVs in Tax-expressing fibroblasts were 10,000-fold higher than in normal fibroblasts and 1000-fold higher in C2C12 myotubes than in C2C12 myoblasts. Expression of the vectors and the endogenous muscle creatine kinase gene was similarly dependent on the maturity of the muscle cultures. One vector with modified LTRs was also tested in vivo in regenerating muscle and showed a delayed pattern of expression in myofibers compared with the vector containing the wild-type LTRs. These vectors can be easily modified to contain different tissue-specific enhancer and promoter elements and the availability of complementing packaging and indicator cells expressing Tax should allow their application in a variety of gene therapy settings.

3T3 Cells↗
PubMed1998

Kupffer cell depletion partially prevents hepatic heme oxygenase 1 messenger RNA accumulation in systemic inflammation in mice: role of interleukin 1beta.

The heme oxygenase 1 (HO-1) gene is rapidly activated in the liver after lipopolysaccharide (LPS) treatment. Ninety minutes after LPS treatment (0.1 mg/kg, intraperitoneally) hepatic HO-1 messenger RNA (mRNA) of mice was 40 times the control value. To investigate the hepatic cellular source of the increased HO-1 transcript, we treated mice with LPS and galactosamine (700 mg/kg, intraperitoneally), a selective transcriptional inhibitor of hepatocytes. Galactosamine prevented the LPS-mediated increase of HO-1 mRNA in the liver, indicating that hepatocytes are the main cell type in which HO-1 mRNA accumulates after LPS treatment. We then tested in vitro and in vivo the hypothesis that LPS-mediated hepatic accumulation of HO-1 mRNA is caused by intercellular communication between Kupffer cells and hepatocytes. Isolated rat hepatocytes showed an increase in HO-1 mRNA compared with controls after 90 minutes of exposure to a LPS stimulated Kupffer cell-conditioned medium. This suggests that soluble mediators from Kupffer cells were responsible for this effect. To study the role of Kupffer cells in vivo, we treated mice with Kupffer cell-inactivating or -depleting agents and LPS. Gadolinium chloride and liposome-encapsulated dichloromethylene diphosphonate lowered LPS-mediated HO-1 mRNA accumulation (by about 50%); in these groups hepatic levels of interleukin (IL)-1beta were decreased, by more than 75%. Methylpalmitate hardly affected hepatic HO-1 mRNA accumulation or IL-1beta content after LPS treatment. There was no relationship between HO-1 mRNA and serum TNF or IL-6 levels. These results suggest that LPS-mediated hepatic HO-1 mRNA accumulation is a hepatocyte response partly caused by soluble mediators, particularly IL-1beta, released from Kupffer cells.

Animals↗
PubMed1998

Immunopathological mechanisms underlying the time-course of Trichinella spiralis cardiomyopathy in rats.

The present study shows that isolated, perfused hearts from rats orally infected with Trichinella spiralis have a reduced left ventricular developed pressure (LVDP), heart rate (HR) and coronary flow (CF). This reduction is considerably enhanced by a single bolus (100 pM) of PAF (platelet activating factor, an eosinophil activator), especially at 21 days post-infection (d.p.i.), which is the time of the maximum increase in blood and tissue eosinophilia. Helminthic DNA analysis shows that, from 21 d.p.i. onwards, the morphological and functional changes in the myocardium cannot be ascribed to the parasite's presence, whereas its antigens and the attendant immunopathological reactions might have a role in the induction of myocardial damage and dysfunction. Some perivascular inflammatory cells (eosinophils and mast cells) appear to undergo degranulation. All these data suggest a complex sequence of events, from acute myocarditis (21 d.p.i.) which may lead in time (48 d.p.i. onwards) to a dilating cardiomyopathy.

Animals↗
PubMed1998

The sympathetic nervous system tonically inhibits peripheral interleukin-1beta and interleukin-6 induction by central lipopolysaccharide.

To study the role of the sympathetic nervous system in the induction of inflammatory cytokines elicited by central lipopolysaccharide, sympathetic chemical denervation was performed by intraperitoneal injection of 6-hydroxydopamine. Rats received the neurotoxin according to the following schedule: 50 mg/kg on days 1 and 2, 100 mg/kg on days 3, 4 and 7. On day 8, lipopolysaccharide (2.5 microg/6 microl/rat) was injected intracerebroventricularly and rats were killed 2 h later. 6-Hydroxydopamine reduced noradrenaline and dopamine content in the spleen by 88.7% and 88.8% respectively, without affecting striatal contents indicating that the chemical sympathectomy had been effective and selective. In sympathectomized rats, lipopolysaccharide raised interleukin-1beta and interleukin-6 serum levels more than in control rats given the vehicle. Tumour necrosis factor-alpha serum levels in sympathectomized rats were no different from those in vehicle-treated rats. Interleukin-1beta and interleukin-6 messenger RNA expression, measured by northern blot analysis, was clearly detectable in adrenals and spleen of rats given lipopolysaccharide. Sympathectomy increased lipopolysaccharide-induced interleukin-1beta and interleukin-6 messenger RNA in adrenals and spleen. Corticosterone basal levels were raised by central lipopolysaccharide and not further changed by sympathectomy. The present study shows that sympathetic nervous system denervation enhances the synthesis and production of peripheral interleukin-1beta and interleukin-6 in rats given central lipopolysaccharide and suggests a tonic inhibitory control of the sympathetic nervous system on these inflammatory cytokines.

Animals↗
PubMed1997

Role of metalloproteases in the release of the IL-1 type II decoy receptor.

The IL-1 type II receptor (decoy RII) is a nonsignaling molecule the only established function of which is to capture IL-1 and prevent it from interacting with signaling receptor. The decoy RII is released in a regulated way from the cell surface. Here, we reported that hydroxamic acid inhibitors of matrix metalloproteases inhibit different pathways of decoy RII release, including the following: (a) the slow (18 h) gene expression-dependent release from monocytes and polymorphonuclear cells exposed to dexamethasone; (b) rapid release (minutes) from myelomonocytic cells exposed to tumor necrosis factor, chemoattractants, or phorbol myristate acetate; (c) phorbol myristate acetate-induced release from decoy RII-transfected fibroblasts and B cells. Inhibition of release was associated with increased surface expression of decoy RII. Inhibitors of other protease classes did not substantially affect release. However, serine protease inhibitors increased the molecular mass of the decoy RII released from polymorphonuclear cells from 45 to 60 kDa. Thus, irrespective of the pathway responsible for release and of the cellular context, matrix metalloproteases, rather than differential splicing, play a key role in production of soluble decoy RII.

Alternative Splicing↗
PubMed1997

IL-13 inhibits TNF production but potentiates that of IL-6 in vivo and ex vivo in mice.

IL-13 was reported to inhibit the synthesis of various cytokines in vitro, including that of TNF. It has divergent effects on IL-6 production, which is increased in endothelial cells and decreased in monocytes. We studied the effect of IL-13 administration on TNF and IL-6 production in vivo in mice. IL-13 (1 microg/mouse, i.v., 10 min to 6 h before LPS) decreased LPS (100 ng/mouse, i.v.)-induced serum TNF levels by 50%, while it increased the levels of IL-6 by fourfold. IL-13 potentiated IL-1beta (100 ng/mouse, i.v.)-induced serum IL-6 levels as well as IL-1- or LPS-induced serum amyloid A. When blood from IL-13-treated mice was stimulated with LPS in vitro, TNF production was decreased fivefold, and that of IL-6 was slightly decreased. We also cultured in vitro the aorta obtained from IL-13-pretreated mice and found that they produce more IL-6 (up to sevenfold) than aorta from control mice. Little or no TNF could be detected in these samples. Thus, IL-13 in vivo inhibits serum TNF but up-regulates serum IL-6. The differential regulation of IL-6 and TNF together with the results of ex vivo experiments could be explained by hypothesizing that the cellular origins of the two cytokines are different.

Animals↗