Initiation and regulation of CNS autoimmunity

Our studies addressed the questions of how self-reactive T cells escape tolerance and what stimuli cause these T cells to initiate autoimmune responses. We employed experimental allergic encephalomyelitis (EAE) as an animal model of multiple sclerosis (MS). Endogenous expression of myelin basic protein (MBP) induces tolerance in T cells that recognize one region of MBP, whereas T cells specific for a different region escape tolerance. Triggers of disease induction were investigated in a T-cell receptor (TCR) transgenic model in which the majority of T cells recognize the MBP epitope that does not induce tolerance. EAE occurs spontaneously in this model and the incidence of disease depends on microbial exposure. EAE can also be actively induced by immunization with MBP peptide accompanied by injection of pertussis toxin as well as by administration of pertussis toxin alone. Immunization with MBP peptide without pertussis toxin, however, stimulates the transgenic T cells, but the activated T cells do not accumulate in the central nervous system (CNS) or induce EAE. Our studies suggest that initiation of autoimmune disease involves complex interactions between the neuroendocrine system as well as the innate and specific immune systems.     

Recent developments in the investigation of thyroid regulation and thyroid carcinogenesis

This review covers new mechanistic information spanning the past 10 years relevant to normal and abnormal thyroid growth and function that may assist in the risk assessment of chemicals inducing thyroid follicular cell neoplasia. Recent studies have shown that thyroid regulation occurs via a complex interactive network mediated through several different messenger systems. Increased thyroid-stimulating hormone (TSH) levels activate the signal transduction pathways to stimulate growth and differentiation of the follicular cell. The important role of TSH in growth as well as in function helps to explain how disruptions in the thyroid-pituitary axis may influence thyroid neoplasia in rodents. New investigations that couple mechanistic studies with information from animal cancer bioassays (e. g., sulfamethazine studies) confirm the linkage between prolonged disruption of the thyroid-pituitary axis and thyroid neoplasia. New initiation/promotion studies in rodents also support the concept that chronic stimulation of the thyroid induced by goitrogens can result in thyroid tumors. Some of these studies confirm previous suggestions regarding the importance of chemically induced thyroid peroxidase inhibition and the inhibition of 3,3',5, 5'-tetraiodothyronine (T4, thyroxine) deiodinases on disruption of the thyroid-pituitary axis leading to thyroid neoplasia. Some comparative physiologic and mechanistic data highlight certain differences between rodents and humans that could be expected to confer an increased vulnerability of rodents to chronic hypersecretion of TSH. New data from epidemiologic and molecular genetic studies in humans contribute further to an understanding of thyroid neoplasia. Acute exposure to ionizing radiation, especially in childhood, remains the only verified cause of thyroid carcinogenesis in humans. Iodine deficiency studies as a whole remain inconclusive, even though several new studies in humans examine the role of dietary iodine deficiency in thyroid cancer. Specific alterations in gene expression have been identified in human thyroid neoplasia, linked to tumor phenotype, and thus oncogene activation and tumor-suppressor gene inactivation may also be factors in the development and progression of thyroid cancer in humans. An analysis by the U.S. EPA Risk Assessment Forum, prepared as a draft report in 1988 and completed in 1997, focused on the use of a threshold for risk assessment of thyroid follicular tumors. New studies, involving several chemicals, provide further support that there will be no antithyroid activity until critical intracellular concentrations are reached. Thus, for chemically induced thyroid neoplasia linked to disruptions in the thyroid-pituitary axis, a practical threshold for thyroid cancer would be expected. More information on thyroid autoregulation, the role of oncogene mutations and growth factors, and studies directly linking persistently high TSH levels with the sequential cellular development of thyroid follicular cell neoplasia would provide further confirmation.     

Cytokines serum levels as the markers of thyroid activation in Graves'' disease

We examined whether central somatostatin prevents an inhibitory effect of central calcitonin-gene related peptide (CGRP) on pancreatic secretion in conscious male Wistar rats (330-330 g). Rats were prepared with separate cannulas for draining bile and pancreatic juice and with a duodenal cannula and an extrajugular vein cannula. In addition, another cannula was stereotactically implanted into the left lateral cerebral ventricle. Rats were placed in restraint cages and experiments were conducted 4 days after the operation without anesthesia. An injection of CGRP (0.1, 1.0 nmol/10 microl) into the left lateral cerebral ventricle (i.c.v.) inhibited pancreatic secretion dose-dependently. To confirm the inhibitory effect of CGRP (i.c.v.) was mediated via sympathetic nerves, phentolamine was injected intravenously (i.v.) bolus (0.5 mg kg(-1)) 0.5-h before CGRP (i.c.v.), followed by continuous infusion of 0.2 mg kg(-1) h(-1). Phentolamine (i.v.) reversed the inhibition produced by CGRP (i.c.v.). An injection of 4 nmol/10 microl somatostatin (i.c.v.) 5 min prior to CGRP injection diminished the inhibitory effect of CGRP (i.c.v.). It is concluded that centrally administered somatostatin diminished the inhibitory action of CGRP (i.c.v.) on pancreatic secretion, probably via inhibiting autonomic (sympathetic) nerve excitation at the central site.     

Cytokines and other markers of intrathecal immune response in patients with herpes simplex encephalitis

Sequential samples of serum and cerebrospinal fluid (CSF), from 9 patients with herpes simplex encephalitis (HSE), were analyzed for cytokines and soluble cytokine receptors. The response to herpes simplex virus was characterized by a vigorous compartmentalized immune response. The intrathecal response comprised three different phases: an acute stage (first week of illness), characterized by elevated CSF levels of interleukin (IL)-6 and interferon-gamma; an early convalescence stage (weeks 2-6 after onset of disease), associated with peaking levels of tumor necrosis factor-alpha and late markers of the specific T cell-mediated immune response, soluble IL-2 receptor, and soluble CD8 antigen (sCD8); and finally, a late convalescence stage, lasting months to years and associated with persistently increased levels of sCD8 in particular. These findings show the compartmentalization and kinetics of the inflammatory response in HSE and demonstrate persistence of the intrathecal inflammatory process, which may have implications for antiviral and antiinflammatory therapy.     

Molecular chaperones are targets of autoimmunity in Ro(SS-A) immune mice

We have used a murine model of experimental anti-Ro(SS-A) autoimmunity to dissect additional intermolecular interactions between the 52-kD Ro (Ro52) and 60-kD Ro (Ro60) autoantigens and molecular chaperones. Immune responses to members of the heat shock protein hsp70 and hsp90 families were measured by immunoblotting and ELISA in sera from mice immunized and boosted with purified recombinant Ro52, Ro60 and La (SS-B). All Ro52 and Ro60 immune sera immunoblotted the inducible glucose-regulated protein grp78 and hsp70 species but not constitutive hsc70 or hsp90. The kinetics of antibody production and reciprocal affinity purification experiments indicated that the grp78 and hsp70 responses were cross-reactive but distinct from immune responses to the primary Ro52 and Ro60 immunogens and the endoplasmic reticulum (ER)-resident chaperone calreticulin. No responses to molecular chaperones were detected in the La-immunized mice. Control immunizations indicated that the recruited grp78 and hsp70 responses were specific for the Ro proteins and not due to immunization with denatured protein. The rapid spreading of immunity to the inducible grp78 and hsp70 in Ro52- and Ro60-immunized mice suggests that these components may co-localize and physically associate under certain physiological conditions which may promote autoimmunization. The potential importance of the ER-resident chaperones grp78 and calreticulin is further supported by their co-localization with Ro in small apoptotic membrane blebs and the finding of a novel putative grp78 binding motif in the carboxyl-terminal region of Ro52.     

MHC regulation of immune responses

The major histocompatibility complex is a group of complex genes situated on the short arm of chromosome 6 in humans. They play an important role in the regulation of the immune response. Autoimmune blistering disease provides an ideal model for studying the role of MHC in autoimmunity. The diseases are organ specific, and in some of them the relevant antigen has been cloned and sequenced. Such information on the antigen will help further define the interactions of the Ag, MHC, and TCR. Use of family studies hopefully will define and localize susceptibility alleles, so that any genetic susceptibility can be identified at the molecular level. It is from these molecular perspectives that molecular therapies could be assigned to restore the immune system.     

Prospective study on thyroid autoimmunity and dysfunction related to chronic hepatitis C and interferon therapy

This study was designed to assess patients with chronic hepatitis C (CHC) for the presence of thyroid autoimmunity and dysfunction, to evaluate the risk of thyroid disorders associated with interferon (IFN) therapy, and to survey the outcome of possible treatment-related thyroid injury. Out of 104 consecutive untreated patients (30 women and 74 men; mean age, 52.7 years), 8 (7.7%) were found seropositive for thyroid autoantibodies (ThyAb), whereas seropositivity in healthy controls was 1/98 (1.3%). The relative increase in risk of developing thyroid autoimmunity associated with CHC was 760% (95% CI, 220-1300%). No patients had abnormalities of thyroid function tests, but on IFN treatment, 3/3 patients showed a rapid over-range rise in circulating thyrotropin, which returned to normal after therapy discontinuation. In the other 5 seropositive patients who refused treatment, thyroid function remained normal. Out of the 58 initially seronegative patients who consented to IFN treatment, 9 (15.5%) developed thyroid autoimmunity. Seven of them (77.7%) had thyroid dysfunction: hypothyroidism in 4 cases, transient thyrotoxicosis in 2 cases. The last patient developed TSH-receptor antibodies and Graves' disease, requiring methimazole therapy. Thyroid function recovered in the former 6 cases following IFN discontinuation. In the 28 initially seronegative patients who refused IFN and participated in a preliminary tauroursodeoxycholic acid trial, antithyroglobulin antibodies alone appeared in one case, but no thyroid dysfunction was observed. The relative risk of thyroid autoimmune disorder associated with IFN therapy was 342% (28-636%). The patients with CHC were unlikely to develop thyroid dysfunction in the absence of IFN therapy, in spite of being ThyAb seropositive. Moreover, a considerable proportion of seronegative patients, when IFN-treated, developed thyroid autoimmunity and then thyroid dysfunction. Both in seropositive and seronegative patients immediate IFN discontinuation normalized thyroid function and hormone replacement therapy was not necessary.     

Vascular endothelium in the regulation of immune response

Endothelial cells cover the entire system of arteries, veins, and lymphatics of the human body. Once viewed as a passive coat, we now know that they represent by themselves a large immunologically active system. In this work, we briefly review endothelial cell models and heterogenicity before interrelating endothelial cells with the immune system. In the latter context, we focus on the role of cytokines and that of the five families of cell adhesions molecules.     

The role of the macrophage in immune regulation

The macrophage plays an important role in both the innate and acquired (humoral and cellular) immune responses. Their specialized derivatives, the dendritic cells (DCs), are uniquely potent in induction of naive T and B lymphocytes, whereas macrophages influence a range of immune responses by antigen recognition, capture, clearance and transport. They recruit haemopoietic cells to local sites of inflammation and immunity and regulate their activities. We have used various myeloid-restricted membrane antigens and receptors as markers and functional contributors to these activities, and briefly review their role in immune regulation in vivo and in vitro.     

Occurrence of thyroid autoimmunity and dysfunction throughout a nine-month follow-up in patients undergoing interferon-beta therapy for multiple sclerosis

Thyroid autoimmunity and dysfunction are a well known side effect of IFN alpha therapy for viral hepatitis and tumors, while the IFN beta effects on the thyroid gland in neurological patients have not been studied. The aim of this longitudinal study was to look for the appearance of thyroid autoimmunity as well as for the occurrence of overt thyroid disease in the patients affected by multiple sclerosis (MS) treated with IFN beta 1b. Eight patients (4 males, 4 females) undergoing r-IFN beta 1b treatment (8 M.U. every other day for 9 months) for relapsing remitting multiple sclerosis entered the study. We have analyzed thyroid function parameters and auto antibody levels before and after 1, 2, 3, 6 and 9 months of therapy. None of them referred to familiar thyroid pathology or presented clinically overt thyroid disease except for one patient (case 4) who showed TPO-Ab pretreatment positivity and another (case 8) who was in therapy with Levothyroxine 100 microg/die for multinodular goiter. The number of patients with appearance of thyroid antibodies has slowly increased, until the third month of therapy with 3 patients out of 7 positive for TPO-Ab. The only case of overt thyroid dysfunction reported by us appeared after nine months of therapy and consisted of a hypothyroidism. Our data suggest that short-term interferon beta treatment is able to induce thyroid autoimmunity (42.8%) and dysfunction (12.5%).     

Peptide-mediated regulation of the allergic immune response

The objective of our study was to investigate if there are abnormalities in signal transducing G proteins in patients with panic disorder. We utilized selective antibodies to quantitate the levels of the G protein alpha subunits that regulate adenylyl cyclase activity (G alpha s and G alpha i2) and phosphoinositide turnover (G alpha q/11) in platelet membranes (and leukocyte membranes for G alpha s), and also carried out pertussis toxin (PT) catalyzed [32P]ADP-ribosylation in platelet membranes from a group of 13 untreated panic disorder patients, 10 untreated social phobia patients, and 12 healthy subjects. There were no significant differences among the three groups in the immunolabeling of G alpha s in platelets or leukocytes, or in the immunolabeling of G alpha i1/2, G alpha q/11, or PT-catalyzed [32P]ADP-ribosylation in platelets. Within the constraints imposed by using peripheral blood cells to reflect brain composition, our results do not provide support for G protein abnormalities in patients with panic disorder. These results contrast with those obtained using identical methodology in bipolar affective disorder, where elevated G alpha s in leukocytes has been reported (Manji et al. 1995).     

Cytokines in hematopoiesis

Hematopoiesis is the process by which mature, functional progeny of the eight major lineages of blood cells are produced from a hierarchy of progressively less mature progenitor and stem cells. The control of hematopoiesis involves intimate cellular interactions between developing blood cells and stromal elements as well as regulation by soluble cytokines, that may act locally in the bone marrow environment or at remote tissue sites. In excess of twenty cytokines that stimulate the production and/or function of hematopoietic cells have now been cloned and are available in purified, recombinant form. The colony-stimulating factors, erythropoietin and the recently discovered thrombopoietin are key regulators of granulocyte/macrophage, erythroid and megakaryocyte/platelet production respectively. The activities of these cytokines have been extensively studied, both in vitro and in vivo, and recent analysis of mice genetically engineered to lack these regulators or their cell surface receptors have provided profound insights into their essential physiological roles. These studies have culminated in the development of these cytokines as valuable clinical reagents.     

Cytokines in implantation

Implantation is a complex process which involves the 'invasion' of the maternal endometrium by the trophoblast surrounding the developing blastocyst. In response to this interaction there is a cellular reaction within the endometrium which has some features analogous to invasion by a tumour and some which are more characteristic of an inflammatory response. In addition, and also in common with cancer and inflammation, there is a release of biologically active molecules, including cytokines, at and around the implantation site. The information on cytokines is complex and often contradictory but it is recognised that they play an important role in the successful establishment of pregnancy. The evidence for this role is examined in this review.     

Cytokines and bioincompatibility

OBJECTIVES: This study explored the mechanisms linking clinical and precordial echocardiographic predictors to thromboembolism in atrial fibrillation (AF) by assessing transesophageal echocardiographic (TEE) correlations. BACKGROUND: Clinical predictors of thromboembolism in patients with nonvalvular AF have been identified, but their mechanistic links remain unclear. TEE provides imaging of the left atrium, its appendage and the proximal thoracic aorta, potentially clarifying stroke mechanisms in patients with AF. METHODS: Cross-sectional analysis of TEE features correlated with low, moderate and high thromboembolic risk during aspirin therapy among 786 participants undergoing TEE on entry into the Stroke Prevention in Atrial Fibrillation III trial. RESULTS: TEE features independently associated with increased thromboembolic risk were appendage thrombi (relative risk [RR] 2.5, p = 0.04), dense spontaneous echo contrast (RR 3.7, p < 0.001), left atrial appendage peak flow velocities < or = 20 cm/s (RR 1.7, p = 0.008) and complex aortic plaque (RR 2.1, p < 0.001). Patients with AF with a history of hypertension (conferring moderate risk) more frequently had atrial appendage thrombi (RR 2.6, p < 0.001) and reduced flow velocity (RR 1.8, p = 0.003) than low risk patients. Among low risk patients, those with intermittent AF had similar TEE features to those with constant AF. CONCLUSIONS: TEE findings indicative of atrial stasis or thrombosis and of aortic atheroma were independently associated with high thromboembolic risk in patients with AF. The increased stroke risk associated with a history of hypertension in AF appears to be mediated primarily through left atrial stasis and thrombi. The presence of complex aortic plaque distinguished patients with AF at high risk from those at moderate risk of thromboembolism.     

Cytokines and asthma

Asthma is a chronic inflammatory lung disease in which eosinophils are one of the most important involved cells. These cells accumulate in the lung because of cytokines, which are able to regulate cellular responses. The role of cytokines is well known in allergic asthma: IL4, IL5, IL3, GMCSF are the principally cytokine involved. IL4 regulate IgE synthesis while IL5, (and IL3) cause the activation and accumulation of eosinophils. In non allergic asthma, whilst only IL5 seemed to be important recent data, shows that also IL4 plays an important role. Therefore nowadays no relevant difference seems to exist between allergic and non allergic asthma; instead the primer is different: the allergen in allergic asthma and often an unknown factor in the non allergic asthma. Recently other cytokines have been proved to play a role in the pathogenesis of asthma. IL8 is chemotactic not only for neutrophils but also for eosinophils and might cause chronic inflammation in severe asthma. IL13 works like IL4, while RANTES seems to be a more important chemotactic agent than IL5. Finally IL10, which immunoregulates T lymphocyte responses, may reduce asthma inflammation. In conclusion cytokine made us to learn more about the pathogenesis of asthma even if we do not yet know when and how asthma inflammation develops.     

Cytokines and cancer

The relationships between cytokines and cancer are multiple and bidirectional. On the one hand, cytokines may directly influence carcinogenesis and metastasis by modifying the tumor phenotype. On the other hand, during tumor progression, modifications of the cytokine expression in the tumor environment may be induced by the tumor cells, leading to a state of immunosuppression reflected by low cytokine expression in tumor stroma. Cytokines also play a role by stimulating the host immune system to generate anti-tumor specific responses. Finally, the use of cytokines as anti-tumor agents has led to objective clinical responses in about 15-25% of patients with metastatic melanoma or renal cell carcinoma, which presents the basis for the development of promising immunotherapeutic approaches for cancer therapy.     

Cytokines and gut

Cytokines are soluble proteins or glycoproteins produced by a wide variety of cell types. Cytokines are local regulatory factors which are involved in cell growth, cell differentiation, inflammation, and immune responses. In the gastrointestinal mucosa, not only inflammatory cells but also epithelial and mesenchymal cells secrete cytokines in response to various stimuli. Inflammatory cytokines are playing critical roles in the inflammation associated with gastrointestinal infections, including Helicobacter pylori infection in the gastric mucosa. Animal studies have shown that abnormal cytokine response may be risk for developing inflammatory bowel diseases, such as ulcerative colitis and Crohn's disease. Cytokines will be important therapeutic targets in these diseases.     

Cytokines and cachexia

Haemoglobin solutions can be an alternative to allogeneic red-cell transfusions because they combine colloid osmotic with oxygen transport properties. Since severe toxic side effects have been overcome by ultrapurification, clinical interest has been focused on haemodynamics changes during application of haemoglobin preparations. The present clinical study examines changes of haemodynamic and oxygen transport parameters during and after haemodilution with ultrapurified polymerized bovine haemoglobin (HBOC-201) in comparison to hydroxyethyl starch (HES). METHODS: After approval of the Ethics Committee, 12 patients (6 males and 6 females, mean age 59 +/- 10 years, ASA 1-2) undergoing elective liver resection were randomly allocated to receive either 3 ml.kg-1 6% HES 70,000/0.5 (group 1) or 0.4 g.kg-1 HBOC-201 (group 2) within 30 min following autologous blood donation of 1 l and substitution with 2 l Ringer's lactate. Measurements of blood gases, haemodynamics, and oxygen transport parameters were performed after induction of general anaesthesia, prior to and after blood donation, during and after infusion, at the beginning of surgery, and in the intensive care unit. RESULTS: Demographic characteristics did not differ between groups. In contrast to the HES group, mean arterial pressure increased by 18% over baseline measurements in group 2. While pulmonary vascular resistance showed a trend to higher values in group 2, systemic vascular resistance increased to a maximum of 42% over baseline in group 2 and was twice as high as in the HES group. The cardiac index was lower in the HBOC-201 group than in the HES group. During and after HBOC-201 infusion, mixed-venous oxygen saturation and content and calculated oxygen delivery were lower in group 2 in comparison to group 1, while the oxygen extraction ratio was higher in group 2. Free haemoglobin reached a maximal concentration of 1.0 +/- 0.2 g.dl-1 30 min after the HBOC-201 infusion was started, but was not detectable in urine over time. The mean intravascular half-life of HBOC-201 was 8.5 h. CONCLUSIONS: Patients did not show any severe complications during and after infusion of HBOC-201. However, vasoconstrictive side effects resulted in increased systemic but not pulmonary resistance. Ongoing studies with higher doses of HBOC-201 applied in a larger number of patients will probably reveal potential clinical consequences of the demonstrated haemodynamic changes.     

NGF content and expression in the rat pituitary gland and regulation by thyroid hormone

The involvement of nerve growth factor (NGF) in neuroendocrine regulation is supported by several lines of evidence. In this paper, we investigated the NGF content and expression in the pituitary gland and other endocrine organs during dysendocrine states (thyroidectomized, adrenalectomized and gonadectomized male rats). We found an increase of NGF-IR in the pituitary gland and testis of hypothyroid rats whereas no differences were found in the adrenal gland and blood. Also, NGF mRNA expression had increased in the anterior pituitary of hypothyroid rats whereas it had not changed after adrenalectomy and gonadectomy. Moreover, other neurotrophins and neurotrophin high-affinity receptors were unchanged in the anterior pituitary of hypothyroid rats. These data indicate that pituitary NGF is selectively modulated by thyroid status of the animal, further supporting a close link between NGF and thyroid hormone.