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Dimitrios Karussis

Publications and source records attributed to Dimitrios Karussis.

18 recordsLinked to original sources
PubMed2006

Transplanted neural precursor cells reduce brain inflammation to attenuate chronic experimental autoimmune encephalomyelitis.

Stem cell transplantation was introduced as a mean of cell replacement therapy, but the mechanism by which it confers clinical improvement in experimental models of neurological diseases is not clear. Here, we transplanted neural precursor cells (NPCs) into the ventricles of mice at day 6 after induction of chronic experimental autoimmune encephalomyelitis (EAE), a model of multiple sclerosis (MS). Transplanted cells migrated into white matter tracts and attenuated the clinical course of disease. NPC transplantation down-regulated the inflammatory brain process at the acute phase of disease, as indicated by a reduction in the number of perivascular infiltrates and of brain CD3+ T cells, an increase in the number and proportion of regulatory T cells and a reduction in the expression of ICAM-1 and LFA-1 in the brain. Demyelination and acute axonal injury in this model are considered to result mainly from the acute inflammatory process and correlate well with the chronic neurological residua. In consequence to inhibition of brain inflammation, precursor cell transplantation attenuated the primary demyelinating process and reduced the acute axonal injury. As a result, the size of demyelinated areas and extent of chronic axonal pathology were reduced in the transplanted brains. We suggest that the beneficial effect of transplanted NPCs in chronic EAE is mediated, in part, by decreasing brain inflammation and reducing tissue injury.

Amyloid beta-Protein Precursor↗
PubMed2006

Neuroinflammation in multiple sclerosis: evidence for autoimmune dysregulation, not simple autoimmune reaction.

Both inflammatory and neurodegenerative components may contribute to the clinical profile of multiple sclerosis (MS) leading to irreversible deficits when they exceed the threshold of compensation. The mechanisms leading to tissue injury in MS are complex. Inflammation appears to be caused by overactive pro-inflammatory T-helper 1 cells, initiating an inflammatory cascade with several cellular and molecular immune components participating in the pathogenetic mechanism. Current treatments are most effective in the inflammatory phase of the disease since they may interfere with various stages of the immune cascade. Recent evidence has emerged that inflammation may not only be destructive, but may also play a part in tissue repair. This has opened up a new aspect of our knowledge of the role of the inflammatory process in MS. Data regarding the role of regulatory cells in particular, imply that specific immunomodulatory strategies that support the function of these particular cellular subpopulations may participate in the downregulation of autoimmune responses in MS.

Autoimmunity↗
PubMed2006

Neuroprotection in multiple sclerosis.

In chronic inflammatory diseases like multiple sclerosis (MS), neuroprotection refers to strategies aimed at prevention of the irreversible damage of various neuronal and glial cell populations, and promoting regeneration. It is increasingly recognized that MS progression, in addition to demyelination, leads to substantial irreversible damage to, and loss of neurons, resulting in brain atrophy and cumulative disability. One of the most promising neuroprotective strategies involves the use of bone marrow derived stem cells. Both hematopoietic and non-hematopoietic (stromal) cells can, under certain circumstances, differentiate into cells of various neuronal and glial lineages. Neuronal stem cells have also been reported to suppress EAE by exerting direct in situ immunomodulating effects, in addition to their ability to provide a potential source for remyelination and neuroregeneration. Preliminary results from our laboratory indicate that intravenous or intracerebral/intraventricular injection of bone marrow derived stromal cells could differentiate in neuronal/glial cells and suppress the clinical signs of chronic EAE. Both bone marrow and neuronal stem cells may therefore have a therapeutic potential in MS. It seems that future treatment strategies for MS should combine immunomodulation with neuroprotective modalities to achieve maximal clinical benefit.

Humans↗
PubMed2006

Tauopathy-like abnormalities and neurologic deficits in mice immunized with neuronal tau protein.

BACKGROUND: A possible role of autoimmunity in Alzheimer disease pathogenesis has recently attracted increasing attention. Vaccination with amyloid-beta peptide was reported to cause marked reduction in amyloid deposition, but it also induced encephalitis. Not much is known regarding neurofibrillary tangle-related autoimmune effects. OBJECTIVE: To use the main component of tangles-microtubule-associated tau protein-to test the feasibility of active induction of a neuroautoimmune disorder in mice. DESIGN: Prospective, randomized controlled animal study. SETTING: University medical center research laboratory. Subjects Female C57BL/6 mice. INTERVENTIONS: Inoculation with recombinant human tau protein emulsified in complete Freund adjuvant and with pertussis toxin. MAIN OUTCOME MEASURES: Clinical, immunologic, pathologic, and behavioral evaluations were performed. RESULTS: Vaccination with tau protein induced histopathologic features of Alzheimer disease and tauopathies, indicated by the presence of neurofibrillary tangle-like structures, axonal damage, and gliosis. Also, mononuclear infiltrates without demyelination in the central nervous system, accompanied by neurologic deficits (such as a limp tail and limb paralysis), were observed. Anti-tau antibodies were detected in the serum of tau-immunized mice. CONCLUSIONS: These results provide a link between tau autoimmunity and tauopathy-like abnormalities and indicate potential dangers of using tau for immunotherapy. This experimental autoimmune tauopathy-like model is due to a pathogenic immune response against an intraneuronal antigen and is not related to myelin antigens.

Alzheimer Disease↗
PubMed2006

[Autoimmune mechanisms in paraneoplastic neurological diseases: the paradigm of opsoclonus myoclonus ataxia syndrome].

Paraneoplastic Neurologic Diseases (PND) are remote complications of certain neoplastic diseases characterized by distinct neurological deficits in the central as well as the peripheral nervous system. The neurological disorders are usually clinically evident before the cancer is identified. PND are rare syndromes believed to have an immunological link where antibodies or activated T cells are acting against self antigens shared by the tumor cells and neurons. Most of these onconeural antigens are located in the cytoplasm-nuclear compartment of the cell, whereas others are located at the membrane and act as receptors or ion channels. This short review discusses the autoimmune mechanisms involved in PND in general and in opsoclonus-myoclonus-ataxia in particular. The article attempts to clarify why in most PND the immune effector mechanisms against onconeural antigens detected in sera of patients may not be the direct cause of the neurological deficit. We elaborate on the difference between the immune response against cytoplasmic-nuclear antigens as opposed to membranal antigens with regard to the fact that: a) the nervous system is considered immune privileged; b) neither the tumors nor the neurons have an optimal expression of MHC class I antigens and onconeural epitopes on the membrane. The availability of onconeural antigens to the immune effectors mechanisms is probably the main reason why there are few animal models for PND.

Autoimmune Diseases↗
PubMed2005

Amelioration of experimental colitis by Copaxone is associated with class-II-restricted CD4 immune blocking.

UNLABELLED: Copaxone modifies TH1 immune response in multiple sclerosis. As Crohn's disease shares TH1 predominance, this study came to investigate the anti-inflammatory response of Copaxone in animal model of colitis. METHODS: Colitis was induced by intra-rectal instillation of TNBS in 2 animal groups; one of them was daily treated intraperitoneally by 300 mug Copaxone starting 48 h post-colitis induction. Both colitis groups were compared to naive group. Eight male C57Bl6 mice were used in each group. At day 12, distal colon was excised for standard scoring, splenocytes were isolated for FACS and serum cytokines were assessed. Splenocytes were in-vitro-stimulated with colitis protein extracts in the presence or absence of Copaxone. Lymphocytes were blocked by either MHC anti-class I or anti-class II antibodies prior to Copaxone administration. RESULTS: Copaxone markedly alleviated macro/microscopic colitis scoring as they decreased from 2.9 +/- 1.1/2.6 +/- 0.8 in colitis group to 1.7 +/- 1/1.5 +/- 0.5 in Copaxone-treated mice (P = 0.03/P = 0.008, respectively) compared to 0 +/- 0/1 +/- 0 in naives (P < 0.001/P < 0.01, respectively). CD4 subsets significantly decreased following Copaxone administration as compared to naive mice (P = 0.05). Although Copaxone-treated mice manifested a block of both serum TH1/TH2 responses, only interferon gamma secreting CD4 cells significantly decreased. NK cells tend to increase following colitis induction (P = 0.08), however, they significantly decreased in Copaxone-treated animals (P = 0.006). NK-T followed NK pattern. Using in vitro studies, Copaxone showed amelioration of T-cell proliferation that was significantly blocked when cells were pre-incubated with anti-MHC class II but not class I antibodies. CONCLUSIONS: Copaxone had class-II-restricted anti-inflammatory effect in our animal colitis model associated with CD4/NK/NKT/TH1/TH2 suppression.

Animals↗
PubMed2005

Extrathymic malignancies in patients with myasthenia gravis.

INTRODUCTION: Myasthenia gravis (MG) is considered a paraneoplastic phenomenon of thymomas in 15% of patients. Co-existence of MG with extrathymic malignancies, and an increased risk of second malignancy in patients with thymoma have been reported. Data on clinical characteristics of MG patients with extrathymic malignancies and the role of concomitant diseases and their treatment are lacking. METHODS: The clinical records of 188 consecutive MG patients were studied retrospectively. We examined whether gender, age, generalized disease, seropositivity for acetyl-choline receptor antibodies, occurrence of thymoma, immunosuppressive therapy and occurrence of other autoimmune diseases determined an increased risk for development of extrathymic malignancy. RESULTS: This group followed the typical epidemiological characteristics of MG. Thirty-three patients (17.6%) had a thymoma. Twenty-nine patients (15.4%) had 30 extrathymic malignant tumors of various origins. Only four patients with extrathymic tumors had an associated thymoma. Tumors were diagnosed between 20 years prior to and 35 years after the appearance of MG. Older age of MG onset was the only risk factor identified for development of malignancy in MG. DISCUSSION: Extrathymic malignancies are common in MG patients, especially in the older age group. There are no specific clinical features of the subgroup of MG patients with cancer. Although MG is not a paraneoplastic phenomenon of extrathymic malignancy, the association between MG and malignancy may be due to a common background of immune dysregulation.

Adult↗
PubMed2005

Polyneuropathy associated with interferon beta treatment in patients with multiple sclerosis.

Peripheral neuropathy has been reported as a side effect of interferon alpha, but not with interferon beta (IFNbeta) treatment. The authors assessed six patients with multiple sclerosis who developed polyneuropathy, or had exacerbation of previously subclinical neuropathy, during treatment with IFNbeta. In five patients the neuropathy improved after discontinuation of treatment and in two patients it relapsed upon rechallenge.

Adult↗
PubMed2004

Hematopoietic stem cell transplantation in multiple sclerosis: experimental evidence to rethink the procedures.

Acute immunosuppression with lymphocytic agents given at maximally tolerated doses, followed by hematopoietic stem cell rescue achieved by autologous bone marrow or peripheral blood stem cell transplantation (BMT), has proved effective in various experimental models of autoimmunity. The rationale for such an approach in autoimmune diseases is based on the concept of lymphoablation of self-reactive lymphocytes followed by de novo immune system reconstitution, which, in the presence of the autoantigens in the thymus, may reinduce self-tolerance. Our previous work shows that in experimental autoimmune encephalomyelitis (EAE), autologous/syngeneic BMT not only prevents the appearance of paralytic signs, but can also partially reverse chronic disease and induce long-term, antigen-specific tolerance. However, there are serious reservations to be considered when interpreting these data and before applying similar protocols in patients with multiple sclerosis. (1) The model of EAE is not a completely reliable model of multiple sclerosis. (2) In animals with chronic EAE, although further relapses were prevented, the established paralysis was usually not reversible. According to recent data, in chronic multiple sclerosis (MS) lesions, damage caused by axonal loss/transection and cortical/spinal cord atrophy is irreversible and probably amenable to immunotherapy. (3) Long-term, antigen-specific tolerance may be induced with BMT, but not in all cases; in passively induced CR-EAE, many of the mice relapsed upon challenge with myelin antigens, which may indicate that the presence of the immunizing, myelin antigens (on the site of immunization) during the process of immune reconstitution is critical for induction of tolerance. Finally, one should weigh the procedure-related risks (including mortality of up to 5%) of bone marrow or peripheral stem cell transplantation (SCT). A more radical solution for autoimmunity may involve the use of non-myeloablative allogeneic transplantation.

Animals↗
PubMed2004

Axonal damage in multiple sclerosis: a complex issue in a complex disease.

Multiple sclerosis is no longer considered to simply be an autoimmune demyelinating disease. Axonal destruction is another central pathological feature and a contributor to the accumulating disability of disease progression. The mechanism underlying axonal pathology has not been fully clarified but does not appear to be a simple one. The relationship between axonal damage and other components of the pathological features such as demyelination, inflammation and remyelination are under intense investigation. Experimental data suggest that therapeutic interventions such as the induction of rapid remyelination may lead to the protection of axons. In addition to immunomodulation, future strategies for neuroprotection may be of great importance.

Adjuvants, Immunologic↗
PubMed2003

Transplanted multipotential neural precursor cells migrate into the inflamed white matter in response to experimental autoimmune encephalomyelitis.

Transplanted neural precursor cells remyelinate efficiently acutely demyelinated focal lesions. However, the clinical value of cell transplantation in a chronic, multifocal disease like multiple sclerosis will depend on the ability of transplanted cells to migrate to the multiple disease foci in the brain. Here, we expanded newborn rat neural precursor cells in spheres and transplanted them intracerebroventricularly or intrathecally in rats. The cells were labeled by the nuclear fluorescent dye Hoechst or by incubation with BrdU to enable their identification at 2 days and 2 weeks after transplantation, respectively. Spheres consisted of PSA-NCAM(+), nestin(+), NG2(-) undifferentiated precursor cells that differentiated in vitro into astrocytes, oligodendrocytes, and neurons. Spheres that were transplanted into intact rats remained mostly in the ventricles or in the spinal subarachnoid space. Following transplantation at peak of experimental autoimmune encephalomyelitis, cells migrated into the brain or spinal cord parenchyma, exclusively into inflamed white matter but not into adjacent gray matter regions. After 2 weeks, many transplanted cells had migrated into distant white matter tracts and acquired specific markers of the astroglial and oligodendroglial lineages. Thus, the inflammatory process may attract targeted migration of transplanted precursor cells into the brain parenchyma.

Acute Disease↗
PubMed2003

Intraventricular transplantation of neural precursor cell spheres attenuates acute experimental allergic encephalomyelitis.

Brain transplantation of neural precursor cells (NPCs) has been proposed to enhance CNS regeneration. As the pathogenesis of most acute CNS diseases involves an inflammatory component, we studied whether NPC transplantation affects brain inflammation. Newborn rat multipotential NPCs were transplanted intraventriculary into acute experimental allergic encephalomyelitis (EAE) rats, a model for disseminated brain inflammation. Cells migrated into inflamed white matter and differentiated into glial cells. NPC transplantation attenuated the clinical severity of EAE and the brain inflammation, indicated by reduction in perivascular infiltrates and decreased expression of ICAM-1 and LFA-1. NPCs inhibited basal proliferation and proliferative responses to Concavalin-A and to MOG peptide of EAE rat-derived lymphocytes in vitro. Purified astrocytes inhibited lymphocyte proliferation in vitro, but did not migrate into EAE brains in vivo, and did not reduce EAE severity or brain inflammation. Thus, transplanted NPCs attenuate acute EAE via an anti-inflammatory mechanism which depends on cell ability to migrate into inflamed brain tissue.

Acute Disease↗
PubMedDate not supplied

Severe skin reaction related to mycophenolate mofetil for myasthenia gravis.

The authors report the development of a papulosquamous psoriatic-like skin eruption following the introduction of mycophenolate mofetil (MM) in a patient with myasthenia gravis (MG). MM is a novel and potent immunosuppressive agent that blocks purine synthesis, thus selectively inhibiting T and B lymphocyte proliferation. Favorable results in refractory and steroid-dependent MG patients have been reported in open-label studies, revealing a rapid onset of action and a safe side effect profile. Drug eruption due to toxicity or immune-mediated damage has not been reported in association with MM. A 32-year-old man with generalized seropositive MG with a highly malignant clinical course was admitted to the authors' department due to an acute papulosquamous, psoriatic-like skin eruption 1 month following treatment initiation with MM. Skin biopsy revealed sparse perivascular infiltrate of lymphocytes intermingled with few eosinophils. Treatment with high-dose steroids together with discontinuation of MM induced a gradual improvement, with complete resolution of the symptoms 2 months later. A severe and fulminant skin eruption in association with MM treatment is described for the first time in the literature. The histopathologic diagnosis of "drug eruption" is supported by the resolution of symptoms following discontinuation of MM. However, other possibilities include an immune-mediated process supported by the presence of lymphocytic infiltrations, the clinical appearance and the distribution of lesions (simulating a psoriatic-like dermatitis), as well as the marked response to steroids.

Adult↗
PubMedDate not supplied

The frequency of multiple sclerosis in jewish and arab populations in greater jerusalem.

A comparison of the incidence rate (IR) and the prevalence rate (PR) of multiple sclerosis (MS) in subgroups of the same ethnic origin, but born and living in different geographical areas, may delineate the relationship between environmental and genetic risk factors for MS. Previous epidemiological studies of MS in Israel did not include the Arab population and used diagnostic criteria that did not include MRI findings. Therefore, we studied the age-adjusted IR and PR of MS in a more recent sample in different population groups, including Arabs, of Greater Jerusalem. We found that the PR of MS in Israeli Jews is higher than previously described. Furthermore, the PR was significantly lower among immigrant Jews from Asia/Africa (A/A) than among native-born Jews of Asian/African origin (I-A/A). Since these groups have similar genetic susceptibilities to MS, the higher PR in the latter is probably due to environmental factors. Our study does not support the effect of latitude on the risk of developing MS since no difference in the PR was found between immigrant Jews from Europe/America (E/A) and native-born Jews of European/American origin (I-E/A). Among Arabs, the PR was similar to that among A/A. Therefore, we hypothesized similarity in environmental etiologic factors for MS between the countries of origin of A/A immigrants and of Arabs communities in Greater Jerusalem. The IR of I-E/A was higher than that of I-A/A and Arabs, although this difference did not reach statistical significance.

Adolescent↗