Caterina Calderaro

Increased expression of dopamine receptors on lymphocytes in Parkinson's disease

Dopamine D1‐like and D2‐like receptors on peripheral blood lymphocytes (PBL) were assayed in 50 de novo patients with idiopathic Parkinsons disease (PD), in 36 neurologic control subjects (multiple‐system atrophy, n = 16; essential tremor, n = 10; other neurodegenerative diseases, n = 10), and in 26 healthy control subjects by radioligand binding assay techniques using [3H]SCH 23390 and [3H]7OH‐DPAT as ligands. Patients with PD revealed a higher density (Bmax) of dopamine D1‐like (p <0.001) and D2‐like (p <0.00001) receptors on PBL than either neurologic or healthy control subjects, whereas no differences in Bmax were observed among patients affected by other neurologic diseases and healthy control subjects. The affinity (Kd) of both radioligands was similar in the groups investigated. The pharmacologic profile of [3H]SCH 23390 and [3H]7OH‐DPAT binding was consistent with the labeling of dopamine D5 and D3 receptor subtypes, respectively. Twenty‐five of the 50 patients with PD were retested after 3 months of therapy with levodopa or bromocriptine. Both treatments reduced the density of D1‐like (p <0.001) and D2‐like (p <0.001) receptors on PBL to values comparable to those of control subjects. The increased density of D1‐like and D2‐like receptors on PBL in de novo PD patients may represent an upregulation mechanism resulting from the diffuse impairment of the dopaminergic system in PD.

β2-glycoprotein I (β2-GPI) mRNA is expressed by several cell types involved in anti-phospholipid syndrome-related tissue damage

We report here the expression of β2‐GPI mRNA by cell types involved in the pathophysiology of the anti‐phospholipid syndrome (APS), i.e. endothelial cells as a target of autoantibodies in the APS, astrocytes and neurones involved in APS of the central nervous system (CNS). Lymphocytes were also included in the study, as it has been demonstrated that patients with systemic lupus erythematosus‐associated CNS diseases have serum anti‐lymphocyte antibodies cross‐reacting with brain antigens, and intrathecally synthesized anti‐neurone antibodies. Reverse transcriptase‐polymerase chain reaction followed by restriction enzyme digestion of the product obtained demonstrated the presence of β2‐GPI mRNA in all cell types here tested, cultured both in presence and absence of fetal calf serum. In both culture conditions, the same cell types were immunoreactive to an anti‐β2‐GPI MoAb, as determined by indirect immunofluorescence technique. Taken together, these results indicate a direct cell synthesis of β2‐GPI, suggesting an antigenic function of β2‐GPI in the APS, including the CNS disease that occurs in this syndrome.

Dopamine transporter immunoreactivity in peripheral blood lymphocytes in Parkinson's disease

Summary. There is increasing interest in the identification of biological markers for the early diagnosis of Parkinsons disease (PD). Previous studies indicate changes of dopamine content, tyrosine hydroxylase immunoreactivity and dopamine receptors in peripheral blood lymphocytes (PBL) in PD. Here we demonstrate a reduction of dopamine transporter immunoreactivity in PBL in the early clinical stages of the disease. These findings contribute to our understanding of the peripheral dopamine system in PD.

Beta-2-glycoprotein I expression on monocytes is increased in anti-phospholipid antibody syndrome and correlates with tissue factor expression

It is well known that monocytes may play an active role in thrombogenesis, since they may express on their surface tissue factor, the major initiator of the clotting cascade. The results of this investigation demonstrate beta‐2‐glycoprotein I (β2‐GPI) mRNA expression by human peripheral blood monocytes, indicating that these cells synthesize β2‐GPI. In addition, we show β2‐GPI expression on cell surface of these cells by flow cytometric analysis, and the presence of this protein in cell lysate by Western blot. Interestingly, β2‐GPI expression on monocytes is significantly increased in patients with anti‐phospholipid syndrome (APS) or systemic lupus erythematosus (SLE) as against healthy blood donors and correlates with tissue factor expression on monocytes. These findings support the view that monocytes are able to synthesize β2‐GPI and suggest that patients with APS may have increased β2‐GPI exposure on cell surface, which leads to persistently high monocyte tissue factor expression and consequently to a prothrombotic diathesis.

Dopamine receptor mRNAs in the rat lymphocytes

It has been suggested that dopamine might play a role in the regulation of the immune system. In this study, reverse transcriptase-polymerase chain reaction (RT-PCR) was used to investigate the expression of mRNA for the different subtypes of dopamine receptors in the rat lymphocytes. D1, D3 and D5 receptor mRNAs were identified. These results provide further evidence for the interaction of dopamine systems and the immune system, and suggest to further investigate whether the immunosuppressive actions of dopamine and dopaminergic drugs might depend on a direct interaction with dopamine receptors on the lymphocyte membrane. Moreover, they suggest the suitability of this animal species to further investigate the correlation between changes in the expression of central and peripheral dopamine receptors produced by manipulations of the dopamine systems.

Myelin basic protein induces heme oxygenase-1 in human astroglial cells

Heme oxygenase‐1 (HO‐1), also known as heat‐shock protein 32 (HSP‐32), is induced in many cells by a large variety of stimuli. Its induction in nervous system cells following toxic and oxidative stress was suggested to play a protective role. Its presence was recently detected by immunohistochemical studies at the level of inflammatory lesions of rat experimental autoimmune encephalomyelitis. In the present study, we demonstrate that myelin basic protein (MBP) induces HO‐1 in human astroglial cells, as shown by Western blots and RT‐PCR. Proteolytic fragments derived from the whole MBP show a different behavior in the HO‐1 induction: MBP152‐167 was able to produce a light but still significant increase in HO‐1 mRNA and protein levels, whereas MBP68‐84 was not. The increase in HO‐1 production seems to be mediated by a Ca2+‐dependent mechanism, since MBP addition to astrocytoma cultures induced a strong and immediate increment of [Ca2+]i increase; MBP152‐167 elicited a delayed and less pronounced [Ca2+]i increase; no [Ca2+]i changes were induced following cell treatment with MBP68‐84. NO pathway involvement in the induction of HO‐1 by MBP was ruled out since the expression of the inducible isoform of nitric oxide synthase was not upregulated in treated cells, neither nitrite levels were modified, as demonstrated by Greiss reaction. The possible significance of HO‐1 induction following MBP stimulation is discussed. GLIA 37:83–88, 2002.

Increased Lymphocyte Dopamine β-Hydroxylase Immunoreactivity in Alzheimer’s Disease: Compensatory Response to Cholinergic Deficit?

There is growing interest in the characterization of peripheral blood lymphocytes (PBL) as a biological tool with which to investigate changes in the neurotransmitter-receptor system in neurodegenerative disorders. Here we show a slight decrease in acetylcholinesterase (AChE) and a significant increase in dopamine β-hydroxylase (DBH) immunoreactivity in the PBL of patients with probable Alzheimer’s disease (AD). Therapy with AChE inhibitors completely reversed the increase in DBH immunoreactivity. We hypothesize that the increase in DBH immunoreactivity may represent a compensatory response to cholinergic impairment. Our findings suggest that neurochemical interactions between the noradrenergic and cholinergic systems may be measured at a peripheral level in AD.

Effects of gonadal steroids on the growth of human pituitary adenomas in vitro

The effects of testosterone (T), dihydrotestosterone (DHT) and methyltrienolone (R 1881) on cell proliferation of eight human pituitary tumors in culture wre assessed by [3H]thymidine incorporation and compared to those of progesterone (Pg) and 17 beta-estradiol. Receptors for androgens (AR), estrogens (ER) and progesterone (PgR) were characterized. AR had a significant inhibitory effect on all AR-positive tumors, whatever their hormonal content. Inhibitory effects of either T and DHT < R1881 < Pg were observed in tumors co-expressing AR and PgR. The inhibitory effect of R 1881 on a PgR-positive/AR-negative tumor suggested that R 1881 action was partially PgR-mediated. The effects of either T or the nonaromatizable DHT and R 1881 were unrelated to ER expression. We conclude that AR can modulate the growth of human pituitary tumors through direct receptor-mediated intracellular pathways which may be common to various pituitary cell types.

Effects of haloperidol on the expression of lymphocyte dopamine receptor mRNAS in the rat

1. Reverse transcriptase-polymerase chain reaction (RT-PCR) was used to investigate the effects of haloperidol treatment (1 mg/kg/day for 2, 7 or 21 consecutive days) on the expression of D1B and D3 dopamine receptor mRNAs in the rat lymphocytes. 2. The expression of D1B receptor mRNA was significantly decreased after 2 days of treatment and progressively returned toward basal values at the end of treatment. Conversely, haloperidol failed to modify the expression of lymphocyte D3 receptor mRNA. 3. These results indicate short-lasting dynamic changes of expression of lymphocyte D1B dopamine receptor mRNA by haloperidol and suggest that the effects of dopamine and dopaminergic drugs on the immune system might be mediated, at least in part, by direct interaction of these substances with dopamine receptors on lymphocyte membrane.

Serum mitogenic activity on in vitro glial cells in Neurofibromatosis type 1

Glial mitogenic effect was investigated in sera from the following groups of subjects: group (1) 31 patients clinically and genetically affected by Neurofibromatosis type 1 (NF1) belonging to different families; group (2) 42 patients without family history of NF1 affected by sporadic neoplasms of the same histogenetic origin as the proliferative lesions that are present in NF1; group (3) 51 healthy volunteers without family history of NF1 nor of neoplastic disease; group (4) 54 clinically healthy relatives of the NF1 patients included in the first group. All NF1 patients and 3/54 healthy relatives had alterations of exons 31 or 32 of NF1 gene. Glial proliferation, measured by [3H]thymidine incorporation, was significantly increased by sera from all NF1 patients and from 23/54 of clinically healthy relatives, as compared to sera from healthy volunteers. This serum mitogenic activity strongly suggests the existence of soluble glial proliferating molecules in NF1 families. The molecular weight (3-30 kDa), the heat- and freeze-stability and the specificity for glial cells, suggest that the molecules responsible for this mitogenic effect are different from the growth factors previously described in NF1-associated tumor extracts and from lymphokines. Within each NF1 family, the maximal serum dilution stimulating glial proliferation was similar both in affected members and in their clinically healthy relatives. Since none of the clinically healthy relatives showing serum mitogenic activity was positive for the NF1 mutation analysis and, conversely, those having altered exons 31 or 32 of NF1 gene did not show any mitogenic activity; these results suggest that the phenotype expression of NF1 might depend not only on the NF1 mutations per se, but also on other genetic or epigenetic factors, such as serum glial proliferating molecules.