Biomedical subjects

B Bonetti

Publications and source records attributed to B Bonetti.

At least 19 recordsLinked to original sources

PubMed2006

Anti-GD2-like IgM autoreactivity in multiple sclerosis patients.

Seric IgM autoreactivity in 100 multiple sclerosis (MS) and 106 control (70 of whom had other neurological diseases) patients was assessed either by immunohistochemistry on normal human CNS tissue or to GD2, GD1a, GD3 by ELISA and thin layer chromatography (TLC) techniques. By double immunohistochemistry, we found that 44% of the total MS population showed seric IgM reactivity to oligodendrocytes and myelin, this finding being particularly frequent in patients with secondary progressive MS. In the non-MS cohort, positive signals were seen only in one patient. In all cases, extraction of lipids from CNS sections abolished the immunoreactivity. Among the gangliosides investigated by ELISA, anti-GD2-like IgM autoantibodies were detected in the serum of 30% of MS patients, a subgroup of whom (below 10%) reacted also with GD1a and/or GD3. More than 85% of MS cases with anti-GD2-like IgM immunoreactivity by ELISA showed also IgM antioligodendrocyte/myelin staining by immunohistochemistry. However, no immunostaining in MS sera was observed when gangliosides were resolved by TLC. A positive correlation with neurological disability was observed, as the Expanded Disability Status Scale of MS patients with anti-GD2-like IgM autoreactivity by ELISA was significantly worse than seronegative MS cases. The results of the present study enforce the role of glycolipids as potential autoantigens and of IgM autoantibodies in MS pathogenesis.

Adult↗

PubMed2003

Hepatitis C virus infection and myositis: a virus localization study.

We report a case of myositis associated with chronic hepatitis C virus infection. Muscle biopsy and immunohistochemistry showed perifascicular atrophy, few necrotic and regenerating fibres, scarce perivascular infiltrates, deposits of immunoglobulin G, C3, fibrinogen and MAC in muscle vessel walls, and non-uniform expression of major histocompatibility complex-I antigens among muscle fibres. Hepatitis C virus NS3 antigen and hepatitis C virus RNA were detected in infiltrating cells but not within muscle fibres or endothelial cells. Our findings suggest that humoral-mediated immune mechanisms, not directly related to hepatitis C virus infection of muscle structures, may sustain the local inflammatory reaction in this patient.

Aged↗

PubMed2002

Multiple sclerosis complexity in selected populations: the challenge of Sardinia, insular Italy.

Several lines of evidence indicate a genetic contribution to multiple sclerosis (MS) both in terms of predisposition to the disease and of immunological mechanisms which are known to play crucial roles in MS pathogenesis. The presence of high- and low-risk areas for MS in neighbouring regions supports the theory that MS predisposition is influenced by a complex interaction of genetic and environmental factors. Therefore, the use of genetically homogeneous and geographically isolated populations becomes an increasing requirement to reduce biasing biological variables. Sardinians fulfil these conditions well because of their different phylogeny from Europeans and the unique selective pressures which shaped their genome. Sardinians display amongst the highest MS prevalence rates world-wide and increasing MS incidence rates over time. Also, MS in Sardinia is linked to distinct human leucocyte antigen (HLA) alleles and associated to different patterns of cytokine production from lymphoid cells of different HLA subtypes. In this context, recent findings and future perspectives on the peculiarities of Sardinian MS concerning genetic, immunological and epidemiological aspects are presented. So far, our results indicate that variations at the level of territorial distribution and HLA-association are present which render MS heterogeneous even in this ethnically homogeneous population.

Humans↗

PubMed2000

Evidence for a role of gammadelta T cells in demyelinating diseases as determined by activation states and responses to lipid antigens.

In this report we review current information on the phenotypic and functional properties of gammadelta T cells in demyelinating disorders. The results support the conclusion that although gammadelta T cells show evidence of activation in patients with either multiple sclerosis (MS) or Guillain Barrè syndrome (GBS), differences exist in the phenotypic and functional properties of these cells between the two diseases. In particular, our data indicate that in patients with MS the Vdelta2 subset is activated and that these cells can be induced to secrete high levels of proinflammatory cytokines. In contrast, in patients with GBS, the Vdelta1 subset is expanded and can be induced to secrete cytokines more associated with a humoral response.

Guillain-Barre Syndrome↗

PubMed2000

Phenotypic and functional properties of gamma delta T cells from patients with Guillain Barré syndrome.

In this study we have examined the phenotypic and functional properties of circulating gamma delta T cells in patients with Guillain Barre syndrome (GBS), in normal healthy controls, and in patients with active multiple sclerosis (MS). Cells expressing the Vdelta2 T cell receptor showed elevated expression of the C-lectin receptor NKRP1A in both GBS and MS, suggestive of an activated state. However, in patients with GBS these cells failed to respond to pyrenil-pyrophosphate derivatives and Vdelta2 + T cell clones derived from these patients released lower levels of IFNgamma than Vdelta2 + clones derived from controls and MS patients. In contrast, in patients with GBS the Vdelta1 + subset was expanded, showed elevated expression of NKRPIA and Vdelta1 + clones derived from these patients secreted high levels of IL-4. Our findings of expanded NKRP-1A +, IL-4-producing Vdelta1 T cells in the GBS patients suggests the possibility that these cells are activated by the recognition of non-protein antigens in an MHC-unrestricted manner and contribute to the humoral response to glycolipids that is a hallmark of this disease.

Adult↗

PubMed2000

Tumor necrosis factor alpha and human Schwann cells: signalling and phenotype modulation without cell death.

The aim of the study was to evaluate the biological response of human Schwann cells (SC) to tumor necrosis factor alpha (TNFalpha) in vitro and to the inflammatory milieu of chronic inflammatory demyelinating polyradiculoneuritis (CIDP). By immunocytochemical and functional assays, we found that SC expressed TNF receptors and that TNFalpha promoted in SC cultures transient activation of transcription factors NFkappaB and c-jun in the absence of apoptosis. In addition, TNFalpha significantly increased the proportion of non-myelin-forming SC expressing the p75 nerve growth factor receptor. Such phenotypic effect was dose-dependent and partially mediated by NFkappaB, as assessed by functional blockage with acetylsalicylic acid. We then extended our study to a human disease in which SC are exposed to TNFalpha. Increased signals for NFkappaB, but not c-jun, molecules were observed by immunohistochemistry on SC nuclei in nerve biopsies from patients with CIDP, as compared with controls. Irrespective of the presence of nerve inflammation, SC showed no evidence of apoptosis. Taken together, our results suggested that SC are potential targets of TNFalpha and that this cytokine exerted no cytotoxic effects either in vivo or in vitro. Rather, TNFalpha may influence the fate of SC by activating transcriptional pathways and modulating their phenotype.

Apoptosis↗

PubMed1999

Hepatitis C virus infection of peripheral nerves in type II cryoglobulinaemia.

Peripheral neuropathy is a frequent complication in patients suffering from type II mixed cryoglobulinaemia (mCGII), a sort of vasculitis that is strongly associated with hepatitis C virus (HCV) infection and characterised by high concentrations of anti-HCV antibodies and HCV RNA in the cryoprecipitates. We report the finding of HCV RNA in homogenates of nerve biopsies from five such patients, by reverse transcription-polymerase chain reaction (RT-PCR) amplification of different regions of the viral genome. HCV RNA was localized in epineurial cells by in situ RT-PCR. Our data suggest that HCV infection of nerves plays a major role in mCGII-associated neuropathy.

Cryoglobulinemia↗

PubMed1999

Activation of NF-kappaB and c-jun transcription factors in multiple sclerosis lesions. Implications for oligodendrocyte pathology.

Oligodendrocytes are a major target of the purported autoimmune response in multiple sclerosis (MS) lesions, but little is known about the mechanisms underlying their demise. Despite the expression of proapoptotic receptors, these cells are rarely seen to undergo apoptosis in situ. On the other hand, cytotoxic mediators present in MS lesions, such as tumor necrosis factor-alpha, are known to generate survival signals through the activation of the transcription factors NF-kappaB and c-jun. The aim of this study was to investigate in chronic active and silent MS lesions and control white matter the expression of c-jun, its activating molecule, JNK, as well as NF-kappaB complex and its inhibitor, IkappaB. By immunohistochemistry we found negligible reactivity for these molecules in control white matter and silent MS plaques. In active MS lesions, double-label immunohistochemistry with oligodendrocyte markers showed up-regulation of the nuclear staining for both NF-kappaB and JNK on a large proportion of oligodendrocytes located at the edge of active lesions and on microglia/macrophages throughout plaques. Oligodendrocytes showed no reactivity for IkappaB, which was predominantly confined to the cytoplasm of microglia/macrophages. We hypothesize that activation of these transcriptional pathways may be one mechanism accounting for the paucity of oligodendrocyte apoptosis reported in MS.

Apoptosis↗

PubMed1998

Multiple sclerosis: expression of molecules of the tumor necrosis factor ligand and receptor families in relationship to the demyelinated plaque.

The molecules that comprise the tumor necrosis factor ligand and receptor (TNF-L and TNF-R) families play important roles in tissue homeostasis and in multiple sclerosis (MS). For example, levels of the TNF ligand (TNF alpha; cachectin) correlate with disease progression and lymphotoxin (LT, TNF beta) has been localized in MS lesions. Members of the TNF-R family are typical signal sensors which upon binding with ligand aggregate and recruit signal transducers. To date, no TNF-R molecules have been reported in MS although TNF-RI and RII have been localized to oligodendrocytes in culture. In the present study, the expression of TNF, LT alpha (the soluble form of LT), LT beta (the beta chain of LT alpha beta, the membrane-bound form of LT), TNF-RI, TNF-RII, LT beta-R, FasL, and Fas receptor in MS lesions has been examined by immunohistochemistry for protein and by RT-PCR for mRNA. In addition, the TUNEL technique for DNA fragmentation was applied to detect apoptosis. The results have shown that contrarily to predictions, oligodendrocytes around active MS lesions frequently expressed TNF-R molecules belonging to the apoptotic cascade. However, these cells did not undergo apoptosis, as judged by TUNEL. On the other hand, lymphocytes (and a few microglial cells) in the same tissue displayed apoptosis. Microglial cells were the major effector cells in the CNS and expressed TNF, LT alpha and FasL. LT beta expression was seen on astrocytes and oligodendrocytes, and LT beta-R on astrocytes. We conclude that TNF-L and TNF-R molecules are extensively expressed in MS, that their expression occurs at high levels but is not specific for MS, and that oligodendrocytes are depleted by a cytolytic mechanism, not by apoptosis.

Demyelinating Diseases↗

PubMed1997

Cell death during autoimmune demyelination: effector but not target cells are eliminated by apoptosis.

The Fas and FasL apoptotic pathway was investigated by protein immunohistochemistry, flow cytometry, and reverse transcriptase-PCR analysis to assess whether it is involved in the elimination of target and/or effector cells from the central nervous system (CNS) during adoptively transferred chronic relapsing experimental autoimmune encephalomyelitis (EAE), a model for multiple sclerosis. In addition to Fas and FasL, we studied Bax, an intracellular protein of the apoptotic cascade, the Bax antagonist and anti-apoptotic molecule Bcl-2, and DNA fragmentation, the final step in the apoptotic pathway. Infiltrating CD4+ T cells and parenchymal microglia expressed Fas, FasL, and Bax, and about half of these cells showed DNA fragmentation, a combination indicative of ongoing apoptosis. Using flow cytometry and reverse transcriptase-PCR, a positive correlation was seen between disease activity and up-regulation of the Fas system; in fact, Fas and FasL were expressed at low levels at the onset of EAE and increased at the height of disease to involve about one-third of all infiltrating lymphocytes. In the normal CNS, Fas immunoreactivity was constitutively present at low levels on oligodendrocytes and was up-regulated in the CNS during the course of EAE. However, oligodendrocytes showed no Bax reactivity or DNA fragmentation and expressed high levels of Bcl-2, as did the majority of infiltrating CD3+ cells, a pattern inconsistent with apoptosis. Thus, while molecules of the apoptotic cascade are well represented in the CNS during EAE, their expression correlates with elimination of infiltrating cells and microglia, not the myelinating cell, the oligodendrocyte.

Animals↗

PubMed1997

Multiple sclerosis: oligodendrocytes display cell death-related molecules in situ but do not undergo apoptosis.

To investigate whether apoptosis is involved in the fate of oligodendrocytes in chronic multiple sclerosis lesions, the pro-apoptotic molecules fas and tumor necrosis factor receptors and the anti-apoptotic molecule bcl-2 were examined by immunohistochemistry, and DNA fragmentation was assessed by an end labeling technique. Fas and both tumor necrosis factor receptors were preferentially expressed on oligodendrocytes in multiple sclerosis lesions, this phenotype being more evident at the lesion edge. The ligand for fasL, was constitutively present at high levels on microglia. The anti-apoptotic molecule bcl-2 was selectively expressed on oligodendrocytes in silent lesions and on astrocytes in active lesions. These molecules were also detected in control material, albeit at lower levels. In chronic active lesions, a few inflammatory cells displayed fas reactivity, whereas the majority expressed bcl-2. DNA fragmentation was found in a number of infiltrating cells and some microglia, whereas, with one possible exception, oligodendrocytes showed no evidence of apoptosis. Thus, while apoptosis is involved in the elimination of infiltrating cells, it plays little or no role in oligodendrocyte depletion in multiple sclerosis, a process that may be related to a lytic pathway. In addition, microglia constitutively displayed the ligand for fas, and appeared to be the major effector cell population in the central nervous system.

Adult↗

PubMed1997

T-cell-mediated epineurial vasculitis and humoral-mediated microangiopathy in cryoglobulinemic neuropathy.

We used immunohistochemistry to assess the role of humoral and cellular factors in endoneurial microangiopathy and epineurial vasculitis in 15 nerve biopsies of patients with axonal neuropathy and monoclonal or mixed cryoglobulinemia (CG). Deposition of immunoglobulins and cytolytic complement was detected in endoneurial capillaries of patients with mixed CG. Epineurial inflammatory infiltrates containing beta2-integrin-positive lymphocytes and monocytes surrounded arterioles expressing cell adhesion molecules, thus suggesting a cell-mediated pathogenesis of the epineurial vasculitis. On the other hand, the absence of immune complex deposition and polymorphonuclear elements suggests a minor role for the humoral mechanisms in the formation of the vasculitic lesions. This study indicates that both cell-mediated mechanisms and immune complexes/cryoglobulins are involved, although at different levels, in the pathogenesis of CG neuropathy.

Aged↗

PubMed1997

Human neoplastic Schwann cells: changes in the expression of neurotrophins and their low-affinity receptor p75.

Neurotrophins are known to influence Schwann cells during development and to promote peripheral nerve regeneration after axonal damage. In neoplastic conditions. Schwann cells from experimentally-induced schwannomas appear to retain their responsiveness to nerve growth factor (NGF), although the role of neurotrophins in the neoplastic process in poorly understood. In this study, human neoplastic Schwann cells (five cases of acoustic schwannoma and two cases of malignant peripheral nerve sheath tumours [MPNST]) were investigated for the expression in situ of molecules of the neurotrophin system. In particular, we studied the 75 kDa low-affinity receptor (p75) and the mRNA for its ligands, NGF and neurotrophin-3 (NT-3). By immunohistochemistry, the p75 receptor was found to be the present at high levels in Schwann cells from acoustic schwannomas, whereas it was very weak or absent in MPNST. Messenger RNA for NGF and NT-3 was detected by reverse transcriptase in situ polymerase chain reaction technique and showed the same fluctuation of p75, being up-regulated in acoustic schwannomas and very weak or absent in MPNST. In normal non-neoplastic tissue, no detectable amounts of either ligand or receptor were observed. Our results indicate that changes in the expression of neurotrophins and their p75 receptor occurred during the neoplastic transformation of Schwann cells. In benign schwannomas, such changes are likely to reflect the loss of axonal contact, while in MPNST they may be related to a complete derangement of cell machinery in the tumour cells.

Adult↗

PubMed1996

Multiple sclerosis: Fas signaling in oligodendrocyte cell death.

Fas is a cell surface receptor that transduces cell death signals when cross-linked by agonist antibodies or by fas ligand. In this study, we examined the potential of fas to contribute to oligodendrocyte (OL) injury and demyelination as they occur in the human demyelinating disease multiple sclerosis (MS). Immunohistochemical study of central nervous system (CNS) tissue from MS subjects demonstrated elevated fas expression on OLs in chronic active and chronic silent MS lesions compared with OLs in control tissue from subjects with or without other neurologic diseases. In such lesions, microglia and infiltrating lymphocytes displayed intense immunoreactivity to fas ligand. In dissociated glial cell cultures prepared from human adult CNS tissue, fas expression was restricted to OLs. Fas ligation with the anti-fas monoclonal antibody M3 or with the fas-ligand induced rapid OL cell membrane lysis, assessed by LDH release and trypan blue uptake and subsequent cell death. In contrast to the activity of fas in other cellular systems, dying OLs did not exhibit evidence of apoptosis, assessed morphologically and by terminal transferase-mediated d-uridine triphosphate-biotin nick-end-labeling staining for DNA fragmentation. Other stimuli such as C2-ceramide were capable of inducing rapid apoptosis in OLs. Antibodies directed at other surface molecules expressed on OLs or the M33 non-activating anti-fas monoclonal antibody did not induce cytolysis of OLs. Our results suggest that fas-mediated signaling might contribute in a novel cytolytic manner to immune-mediated OL injury in MS.

Adult↗

PubMed1996

[Radical radiotherapy in T2N0 glottic laryngeal carcinomas].

The present work analyzes the clinical results obtained at the Istituto del Radio in Brescia, Italy, using radiotherapy in the treatment of T2N0 glottic carcinomas. The analysis covers a sampling of 127 patients who had been treated using fixed field with 60Co or linear accelerator (high energy photons) technique delivering a minimum target dose of 60 Gy over the course of a 6-week period; 200 cGy a day. The purpose of the present study was to evaluate: treatment response 3 months after treatment was suspended using the WHO nomenclature; Overall Survival Rate and Actuarial Disease-Free Survival Rate at five and ten years from the end of treatment comparing the results obtained in cases of T2a and T2b; biological cost of treatment in terms of late recurrences. Three months after treatment had ended, a complete response was seen in 95% of the patients. The overall survival was 85% at five years while the NED survival was 67% at five years. Surgical salvage made it possible to treat 44% of those who did not respond to radiotherapy or who had a recurrence. Late recurrence rate was 4.7%. The clinical results are slightly lower than those obtained in the literature for surgical series in terms of survival probability. They were, however, certainly better in terms of good vocal preservation.

Carcinoma, Squamous Cell↗

PubMed1995

The efficiency of translation termination is determined by a synergistic interplay between upstream and downstream sequences in Saccharomyces cerevisiae.

In a recent study we found that the efficiency of translation termination could be decreased several hundred fold by altering the local sequence context surrounding stop codons in the yeast Saccharomyces cerevisiae. Suppression of termination was shown to be mediated by near-cognate tRNA mispairing with the termination codon. We have now examined in greater detail how the local sequence context affects the efficiency of translation termination in this organism. Our results indicate that the sequence immediately upstream of the termination codon plays a significant role in determining the efficiency of translation termination. An extended termination sequence (containing the stop codon and the following three nucleotides) was also found to be a major determinant of termination efficiency, with effects attributable to the fourth nucleotide being largely independent of the termination codon. For the UGA and UAA stop codons, the influence of the fourth position on termination efficiency (from most efficient to least efficient termination) was found to be G > U,A > C, while for the UAG codon it was U,A > C > G. These sequence-specific effects on the efficiency of translation termination suggest that polypeptide chain release factor (or another molecule that may play a role in translation termination, such as rRNA) recognizes an extended termination sequence in yeast. A previous study found a statistically significant bias toward certain tetranucleotide sequences (containing the stop codon and the first distal nucleotide) in several organisms. We found that tetranucleotide sequences most frequently used in yeast are among the most efficient at mediating translation termination, while rare tetranucleotide sequences mediate much less efficient termination. Taken together, our results indicate that upstream and downstream components of an extended sequence context act synergistically to determine the overall efficiency of translation termination in yeast.

Amino Acid Sequence↗

PubMed1995

Role of HIV in the pathogenesis of distal symmetrical peripheral neuropathy.

We report the results of a clinical, electrophysiological and pathological study conducted in 18 AIDS patients presenting a distal symmetrical predominantly sensory polyneuropathy (DSPN) characterized by painful dysesthesias as main complaint. Onset of the neuropathy was at CDC (Center for Disease Control) stage II in 2 patients, at CDC stage III in 5 patients and at CDC stage IV in the remainder. Electrophysiological investigation confirmed the presence of an axonal alteration in the sensory nerves, but also revealed motor involvement in all cases. The neuropathological features of sensory nerves were fiber loss and axonal degeneration with macrophagic activation. The expression of monocyte-macrophage markers and of major histocompatibility complex class II antigens appeared up-regulated in endoneurial ramified cells, while expression of CR3, a complement receptor involved in the process of phagocytosis, was down-regulated. In six nerve biopsy samples and in two out of five DSPN dorsal root ganglia we found HIV-related mRNA and protein located in scattered cells of the endoneurium which we presume to be macrophages. These data suggest that: (a) DSPN may occur early in the course of the disease and is not limited to later stages; (b) DSPN is not a ganglionitis but is actually a sensory-motor neuropathy; (c) the virus enters the peripheral nervous system and induces changes in the immunocompetent cell population with activation of macrophages. Storage of the virus inside macrophages may act both as a reservoir for the virus and as a putative cause of nerve damage, probably through release of cytotoxins and/or interaction with trophic factors.

Acquired Immunodeficiency Syndrome↗

PubMed1995

Experimental induction of myelin changes by anti-MAG antibodies and terminal complement complex.

We investigated the role of anti-myelin-associated glycoprotein (MAG) IgM and complement (C) in the pathogenesis of myelin alterations occurring in patients with anti-MAG-associated polyneuropathy. For this purpose, we separately studied the effects of anti-MAG antibodies and terminal C complex (TCC) after injection into the rabbit sciatic nerve. The two different local treatments produced identical ultrastructural abnormalities such as intramyelinic edema, myelin vesiculation and, in particular, separation of the major dense lines with the formation of widely spaced myelin, a peculiar feature encountered in human peripheral nerve disorders with circulating anti-myelin monoclonal IgM. In nerves treated with anti-MAG IgM ultrastructural myelin alterations were concurrent with activation of the rabbit's own C to the formation of TCC. Contrary to the immunological and ultrastructural findings obtained in C-sufficient animals, in C6-deficient rabbits injected with anti-MAG IgM no myelin alterations nor C completion were observed. This study identifies anti-MAG IgM as the mediator and the C as the effector of myelin changes observed in the present model and, for extension, in human neuropathies associated with anti-MAG IgM.

Animals↗