E. Traggiai

Synthesis and release of neurotoxic kynurenine metabolites by human monocyte-derived macrophages

We studied the regulation of the kynurenine pathway of tryptophan metabolism in human monocyte-derived macrophages (MDM) with the aim of evaluating macrophage involvement in inflammatory neurological disorders. Cultured MDM metabolized tryptophan and released kynurenine metabolites, including the excitotoxin quinolinic acid (QUIN). Lipopolysaccharides (LPS) or the pro-inflammatory cytokines INFgamma and TNFalpha increased, while IL 4 or IL 10 inhibited the rate of tryptophan metabolism and the release of QUIN. The incubation media of INFgamma-exposed MDM caused neuronal death in primary cultures of mixed cortical cells. Glutamate receptor antagonists or poly(ADP-ribose) polymerase inhibitors significantly reduced this death, thus suggesting new possibilities for the treatment of neuronal damage in neuroinflammatory disorders.

IL-7-enhanced T-cell response to myelin proteins in multiple sclerosis

In this study, we investigated the in vitro proliferative response of peripheral blood T lymphocytes from MS patients and controls to MBP and MOG either in the absence or in the presence of the conditioning factor IL-7. In the absence of IL-7, T-cell reactivity to MOG and MBP was similar in MS patients and controls even if an increased MBP response was found in a subgroup of patients with active disease. In the presence of IL-7, increased T-cell reactivity to MBP was observed in MS patients suggesting that their MBP-specific T cells are in a different functional state.

Short-term dynamics of circulating T cell receptor V beta repertoire in relapsing–remitting MS

To understand the short-term dynamics of the circulating T cell receptor V beta (TCRBV) repertoire in relapsing-remitting multiple sclerosis (MS), we monitored the TCRBV profiles of untreated MS patients and healthy controls. Expansions of TCRBV genes in MS patients were significantly more frequent than in controls (P<0.001), were predominantly oligoclonal (80%) and were significantly correlated with immune responses to myelin basic protein (MBP) (P<0.02) and with inflammatory disease activity detected by magnetic resonance imaging (MRI) (P<0.05). Autoreactive T cell responses against myelin antigens may be implicated in perturbations of TCR repertoire in untreated MS patients, detectable even in the absence of clinically evident manifestations.

Short-term evolution of autoreactive T cell repertoire in multiple sclerosis.

T cells reactive to self‐antigens are present in the peripheral blood of patients with autoimmune diseases as well as in healthy subjects. Although T cell‐response to the self‐myelin antigen myelin basic protein (MBP) has been widely investigated in multiple sclerosis (MS) patients, very little is known about the evolution over time of this response and its correlation with the disease activity. In recent years magnetic resonance imaging (MRI) techniques have provided new tools for following the inflammatory activity in the central nervous system (CNS) of MS patients. In the present study the T cell response to MBP was longitudinally investigated in terms of frequency, epitope specificity, and cytokine production profile in four patients with relapsing‐remitting MS enrolled in a gadolinium‐enhanced MRI serial study. In spite of different profiles of inflammatory activity within the CNS, all the patients examined showed major changes in their reactivity to MBP during the follow‐up period in terms of both frequency and epitope specificity. Episodic expansions of MBP‐specific T cell populations were observed in each patient, and overall they did not correlate with disease activity. In these patients the expansions: 1) occurred in the context of a steady level of disease activity, 2) correlated with a burst of CNS inflammation, 3) followed the appearance of a new active lesion, and 4) were observed even in the absence of detectable signs of CNS inflammation during the entire follow‐up period. These results suggest that the evolution over time of the T cell response to a self‐antigen such as MBP is more complex than previously expected. The short‐term repertoire dynamics of autoreactive T cells in MS underscore the importance of longitudinal studies for evaluating autoreactivity to myelin antigens and probably to any self‐antigen in other autoimmune diseases. J. Neurosci. Res. 66:517–524, 2001.

Decrypting the spectrum of antigen‐specific T‐cell responses: the avidity repertoire of MBP‐specific T‐cells

Myelin basic protein (MBP) is a well‐characterized autoantigen potentially involved in the pathogenesis of the most common human demyelinating disease of the central nervous system (CNS), multiple sclerosis (MS). It is known that MBP‐specific T‐cell responses differ widely among different individuals and also within a single donor in terms of fine specificity and functional characteristics including the avidity in antigen recognition. In this report, we demonstrate that the in vitro selection of MBP‐reactive T‐cell repertoire is strictly dependent upon the antigen dose used in the primary cultures. MBP‐specific T‐cell lines (TCLs) were generated from MS patients and healthy donors using different antigen concentration in cultures (0.1 to 50 μg/ml). In both MS patients and controls, the number of obtained T‐cell lines was affected by the antigen concentration. In addition, low and high antigen concentrations selected in vitro different T‐cell populations in terms of peptide specificity patterns and different functional avidities in antigen recognition. Low concentrations of MBP in the primary cultures yielded a small number of TCLs recognizing the specific antigen with higher avidity whereas high antigen concentrations allowed the in vitro expansion of a higher numbers of T‐cells recognizing MBP with lower avidity. The use of different antigen concentrations in the primary cultures can be applied as a simple experimental system to investigate the overall avidity repertoire of antigen‐specific T‐cell response in humans. J. Neurosci. Res. 59:86–93, 2000

Recombinant MOG from baculovirus inhibits anti-hMOG(30-50) antibodies detected by the synthetic antigen [Asn31(Glc)]hMOG(30-50)

Elena Nardi, Silvia Mazzucco, Sabrina Mata, Mario Chelli, Benedetta Mazzanti, Elisabetta Traggiai, Mauro Ginanneschi, Francesco Pinto, Luca Massacesi, Marco Vergelli, Hubert Kalbacher, Francesco Lolli, and Anna M. Papini Dipartimento di Chimica Organica “Ugo Schiff” and C.N.R. CSCEA, Universita degli Studi di Firenze, I-50121 Firenze, Italy; Servizio di Neurofisiopatologia, Dipartimento di Scienze Neurologiche e Psichiatriche, and Dipartimento di Scienze Neurologiche e Psichiatriche, Universita degli Studi di Firenze, I-50134 Firenze, Italy; and Medizinisch und Naturwissenschaftliches Forschungszentrum, Universitat Tubingen, D-72074 Tubingen, Germany.

The affinity spectrum of myelin basic protein-reactive T cells

The breakdown of the immunological tolerance to myelin components is probably crucial in the pathogenesis of multiple sclerosis (MS). Even if the target autoantigen is yet unknown, myelin basic protein (MBP) has been studied in greatest detail [1, 2].