Trace amines (TAs) such as β-phenylethylamine, p-tyramine, or tryptamine are biogenic amines found in the brain at low concentrations that have been implicated in various neuropsychiatric disorders like schizophrenia, depression, or attention deficit hyperactivity disorder. TAs are ligands for the recently identified trace amine-associated receptor 1 (TAAR1), an important modulator of monoamine neurotransmission. Here, we sought to investigate the consequences of TAAR1 hypersignaling by generating a transgenic mouse line overexpressing Taar1 specifically in neurons. Taar1 transgenic mice did not show overt behavioral abnormalities under baseline conditions, despite augmented extracellular levels of dopamine and noradrenaline in the accumbens nucleus (Acb) and of serotonin in the medial prefrontal cortex. In vitro, this was correlated with an elevated spontaneous firing rate of monoaminergic neurons in the ventral tegmental area, dorsal raphe nucleus, and locus coeruleus as the result of ectopic TAAR1 expression. Furthermore, Taar1 transgenic mice were hyposensitive to the psychostimulant effects of amphetamine, as it produced only a weak locomotor activation and failed to alter catecholamine release in the Acb. Attenuating TAAR1 activity with the selective partial agonist RO5073012 restored the stimulating effects of amphetamine on locomotion. Overall, these data show that Taar1 brain overexpression causes hyposensitivity to amphetamine and alterations of monoaminergic neurotransmission. These observations confirm the modulatory role of TAAR1 on monoamine activity and suggest that in vivo the receptor is either constitutively active and/or tonically activated by ambient levels of endogenous agonist(s).

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According to international criteria, autoimmune hepatitis (AIH) type 1 is characterized by the presence of antinuclear or anti-smooth muscle antibodies (SMA) with F-actin specificity. SMA have been found in 85% of AIH patients, but are not specific to this disease, and anti-F-actin specificity is not always verified when SMA are detected. The objective of this study was to determine the diagnostic value of anti-F-actin antibodies in a large population. A multicenter study involving 12 clinical centers was performed. Patients were selected on the basis of the presence of F-actin SMA detected by indirect immunofluorescence (IIF) on rat liver-kidney-stomach sections and was confirmed by IIF on Hep2 cells treated with colchicine, or F-actin dot-blot. The clinical status of patients was determined from their medical records. One hundred sixty-eight patients were included: 76% women, 24% men; mean age of 45 years (range, 2-88 years), with a bimodal age distribution. Sixty percent had AIH type 1, and 40% had another disease. In the group of women younger than 25 years, 90% had AIH type 1. Other pathologies associated with antiactin were other liver diseases (19%), including viral hepatitis C (7%), and non-liver diseases (21%), including connective tissue diseases (12%). Antibody titers were higher in AIH than in other diseases. Antiactin antibodies are of major diagnostic value in AIH, especially in young women; they may be found in other disease settings, but mostly at low levels.

SummaryIn an attempt to evaluate the frequency of autoimmune markers in autoimmune thrombocytopenic purpura (AITP) and to determine if autoimmune markers in patients with isolated AITP were associated with particular disease manifestations, we analyzed records of 122 consecutive adults with AITP. Twenty-nine patients (24%) had significant titers of one or several autoimmune markers at AITP onset. Among them, 16 (13%) had antinuclear antibodies. The presence of autoimmune markers did not correlate with presenting feature, response to treatment or long-term outcome of AITP. Six patients (5%) developed seven autoimmune diseases during follow-up, comprising systemic lupus erythematosus, an antiphospholipid syndrome, autoimmune haemolytic anemia (n = 2), Grave’s disease, Hashimoto’s disease and primary biliary cirrhosis. At AITP onset, three of these patients had isolated biological markers of the autoimmune disease they later developed. The annual average incidence rate of autoimmune diseases was 1% per patient-year in the entire group and 0.4% in the group of patients with no autoimmune markers at AITP onset. This low rate is probably due to careful assessment at diagnosis for concomitant overt autoimmune disease. We recommend extensive screening for autoimmune markers at AITP onset, and careful follow-up of patients with autoimmune markers. Routine screening for autoimmune markers during AITP follow-up is not necessary for patients with no autoimmune markers at AITP onset.Systemic lupus erythematosus (SLE) and other autoimmune disorders can complicate autoimmune thrombocytopenic purpura (AITP) or be diagnosed concomitantly with otherwise unremarkable AITP (1, 2). However, the frequency and prognostic value of isolated autoimmune markers (i. e. not associated with an autoimmune disorder), particularly antinuclear antibodies (ANA) at AITP onset or during follow-up is controversial (3-8). For example, the committee organized by George et al. (9) to write guideline on the diagnosis and treatment of AITP stated that the search for ANA and lupus anticoagulant were of “uncertain appropriateness at diagnosis and during follow-up”. In an attempt to help practicians to make decisions, we analyzed the frequency of autoimmune markers and autoimmune disorders at onset and during the follow-up in 122 adults with AITP and no overt autoimmune disease at diagnosis. These consecutive patients were followed by the same physician for a mean period of 6 years, and had routine screening tests for autoimmune markers and disorders at onset, before steroid therapy, and regularly during follow-up.