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Biomedical subjects

B Grubeck-Loebenstein

Publications and source records attributed to B Grubeck-Loebenstein.

At least 55 records · Page 3Linked to original sources
PubMed1997

Primary and secondary alterations of immune reactivity in the elderly: impact of dietary factors and disease.

The function of the immune system declines with age. It is the aim of the present review to demonstrate that it makes sense to distinguish between primary and secondary alterations of immune reactivity in the elderly. Primary changes occur as the result of an age-dependent intrinsic decline of immune responsiveness. They also occur in healthy persons, i.e. persons selected according to the criteria of the SENIEUR protocol of the European Community's Concerted Action Program on Aging (EURAGE). T lymphocytes are hereby more severely affected than B cells or antigen presenting cells, possibly due to the involution of the thymus, which is almost complete at the age of 60. Secondary immunological changes occur as the result of environmental factors including diet, drug intake, physical activity etc. or are alternatively due to underlying diseases. In this article, the effects of high lipid intake as well as the impact of diseases, such as for instance Alzheimer's disease and atherosclerosis, will be addressed. The results underline the complexity of immunological alterations to be expected in old age. Changes in the aging immune system represent an opportunity for increased frequency and severity of disease and endanger the protective effect of vaccination.

Aged↗
PubMed1997

Cytokine production in response to stimulation with tetanus toxoid, Mycobacterium tuberculosis and influenza antigens in peripheral blood mononuclear cells and T cell lines from healthy elderlies.

Little is known about the type 1/type 2 T cell dichotomy in old age. Peripheral blood mononuclear cells (PBMC) and T cell lines from old and young healthy individuals were therefore analyzed for their production of interferon gamma (IFN-gamma) and interleukin 4 (IL-4). Tetanus toxoid (TT), purified protein derivative of Mycobacterium tuberculosis, inactivated influenza virus and OKT-3 were used as stimuli. RT-PCR and ELISA determinations were performed. When stimulated with TT, PBMC from young and old individuals expressed IL-4, but produced little IFN-gamma. All other stimuli induced a pronounced IFN-gamma production, while little or no IL-4 was expressed. T cell lines, regardless of their specificity or the donor age, produced IFN-gamma and IL-4. The quantities of cytokines produced did not significantly differ between the age groups. The capacity of the immune system to trigger type 1 and type 2 T cell responses is thus well preserved in old age.

Adult↗
PubMed1996

T cells from rejected human kidney allografts respond to heat shock protein 72.

The immune response to heat shock proteins (hsps) is gaining more and more interest. Members of the 65 and the 70 kDa hsp families have been shown to be target molecules of the immune system in autoimmune diseases, in cancer immunity and recently in the rejection of rat heart allografts. It was therefore the aim of the present study to investigate whether T cells propagated from two rejected human renal allografts also recognised hsps. In vivo activated interleukin-2 (IL-2) receptor positive T cells were expanded from renal allografts, which had been removed because of irreversible rejection, by 1 week of culture in IL-2 only, followed by stimulation with OKT-3 in combination with IL-2. One T cell line was obtained from each graft. FACS analysis of the lines demonstrated that 51% and 53% of the cells were CD4+ and 45% and 42% CD8+; 4% and 5% were gamma delta + T cells. Both lines had a significant proliferative response when stimulated with recombinant human hsp 72. In contrast, hsp 65 did not induce stimulation. The lines also showed a proliferative response upon stimulation with epithelial kidney cells, purified and cultured from the respective rejected kidneys. These results demonstrate that T cells propagated from rejected human kidney allografts recognize hsp 72. This suggests that hsp-specific T cells may play a role in the rejection process of allograft kidneys.

Cell Line↗
PubMed1996

Morphologically and functionally intact dendritic cells can be derived from the peripheral blood of aged individuals.

Dendritic cells are antigen-presenting cells (APC), which are crucial for the initiation of an immune response. In spite of the well known decline of immune function in old age, no information is yet available on whether dendritic cells are also affected by the ageing process. It was therefore the aim of this study to compare peripheral blood dendritic cells (DC) from old and young healthy individuals. Using granulocyte-macrophage colony-stimulating factor (GM-CSF) and IL-4, DC were propagated from peripheral blood mononuclear cells (PBMC). The obtained cell populations had a typical dendritic morphology and expressed HLA class I and class II, CD23, CD32, CD40, CD44 and CD54, but not CD3 and CD19. Larger numbers of DC were obtained from old individuals than from young ones in spite of a similar expression pattern of surface molecules. DC from aged persons also survived better under in vitro culture conditions. When tested for their antigen-presenting capacity, DC from young and old individuals were equally effective in inducing the proliferation of tetanus toxoid-specific T cell clones after antigenic stimulation. Peripheral blood DC from aged individuals may thus still function as powerful APC. They may represent useful tools for immunotherapy in the aged.

Adolescent↗
PubMed1996

Retrobulbar fibroblasts from patients with Graves' ophthalmopathy induce downregulation of APO-1 in T lymphocytes and protect T cells from apoptosis during coculture.

Retrobulbar fibroblasts are a main target of the immune process in Graves' ophthalmopathy (GO) and have been shown to have unique metabolic qualities. The aim of our study was to analyze the immunoregulatory properties of retrobulbar fibroblasts and particularly whether fibroblasts were able to protect T cells from apoptosis. Retrobulbar fibroblasts from patients with GO spontaneously expressed higher concentrations of HLA class I and HLA class II (p<0.05) than control cells, whereas basal CD54 expression was unimpaired. Stimulation with IFN gamma led to a more pronounced increase in HLA class I, class II and CD54 in autoimmune fibroblasts than in control cells (p<0.05). Fibroblasts from both groups had the capacity to prevent apoptosis in preactivated peripheral T cells during coculture. T cell survival was, however, more pronounced after coculture with retrobulbar fibroblasts than with control cells (p<0.05). Prevention of T cell death was associated with a decreased expression of APO-1 on the T cell surface, whereas the bcl-2 expression of the T cells remained unchanged. Our results suggest that the increased expression of immunoregulatory molecules combined with a pronounced capacity of autoimmune fibroblasts to protect infiltrating T cells from apoptosis might at least partly explain the site selectivity as well as the perpetuation of the extrathyroidal manifestation of Graves' disease.

Apoptosis↗
PubMed1996

Regulation of CD95 (APO-1) expression and the induction of apoptosis in human T cells: changes in old age.

CD95 (APO-1) is a member of the TNF/nerve growth factor receptor superfamily, which is expressed on the surface of different types of cells. Cross-linking of CD95 leads to the induction of apoptosis. This may be of importance in many physiological systems, but seems to play a special role for the maintenance of immunological homeostasis. In view of the known decline of immune function in old age it seemed of interest to study the expression and inducibility of CD95 in peripheral blood T lymphocytes from young and old healthy subjects selected according to the guidelines laid down in the Senieur protocol of the European Community's Concerted Action Programme on Aging. Resting T cells did not express CD95. T cell activation by anti-CD3 monoclonal antibody (OKT3) did, however, lead to a rapid increase in the number of CD95 expressing cells. This increase was slower and less pronounced in old healthy subjects than in young ones. The activation-induced increase in CD95 expression was followed by a decrease, which was observed in both age groups, but was less pronounced in old subjects. Under long-term culture conditions T cell lines derived from both young and old individuals progressively lost the capacity to decrease the expression of CD95 at the end of their activation cycle and an increasing susceptibility to activation-driven programmed cell death was noted. The latter change was more pronounced in T cell lines derived from aged donors. The results suggest that a lowered sensitivity in the regulation of CD95 as well as an increased susceptibility to apoptosis-inducing mechanisms during clonal expansion are features of T cell senescence.

Adult↗
PubMed1996

The production of an amyloidogenic metabolite of the Alzheimer amyloid beta precursor protein (APP) in thyroid cells is stimulated by interleukin 1 beta, but inhibited by interferon gamma.

Thyroid epithelial cells have been shown to have a high APP expression and to produce large amounts of its metabolic derivatives, namely secreted APPs and a potentially amyloidogenic 41-kDa C-terminal fragment. It was the aim of the present study to analyze how APP production and metabolism were regulated in human thyroid cells. The effects of three cytokines, interferon gamma (IFN gamma), interleukin 1beta (IL-1 beta) and transforming growth factor (TGF) beta, were investigated. Cell extracts and supernatants were studied by immunoblotting using specific N- and C-terminal APP antibodies. Quantification was performed by densitometric scanning. We demonstrate that IFN gamma has a strong suppressive effect on the production and metabolism of APP. From a concentration of 30 U/ml upwards it reduces the cellular APP content, decreases the amounts of secreted APPs and inhibits the generation of the 41-kDa amyloidogenic APP fragment. In contrast, IL-1 beta has a stimulatory influence on the generation of the amyloidogenic 41-kDa APP metabolite, but does not affect the cellular holoprotein or APPs. TGFbeta has no significant effect on APP. Our results demonstrate that cytokines can regulate APP production and metabolism in thyroid cells. IFN gamma is the first naturally occurring agent described to inhibit the generation of amyloidogenic APP fragments. It may be of relevance in preventing amyloid deposition during inflammatory processes in the thyroid gland, but may exert a similar protective effect in other non-neuronal and neuronal tissues.

Adult↗
PubMed1995

Thyroid epithelial cells produce large amounts of the Alzheimer beta-amyloid precursor protein (APP) and generate potentially amyloidogenic APP fragments.

The Alzheimer beta-amyloid precursor protein (APP) is a transmembrane glycoprotein from which the amyloid beta-protein is proteolytically derived. The latter is a hydrophobic peptide that can aggregate and forms the core of the senile plaques found in the brains of patients suffering from Alzheimer's disease (AD). In view of the known association between familial AD and thyroid autoimmune disease, the expression pattern and cellular processing of APP in human thyroid cells were investigated. Cultured thyroid epithelial cells and homogenized thyroid tissue from normal and pathological thyroid samples were analyzed by immunoblotting using specific N- and C-terminal APP antibodies as well as by reverse transcription-polymerase chain reaction in which two sets of oligonucleotide primers were used. The results of these studies demonstrated that APP isoforms 770 and 751 were expressed in fresh thyroid extracts as well as in cultured thyroid epithelial cells, with APP 770 being the predominant form. Compared to other types of cells, such as lymphocytes and fibroblasts, thyroid epithelial cells produced larger amounts of APP. Most of the mature protein was cleaved within the amyloid beta region, as a result of which a large N-terminal APP fragment was released into the culture medium, whereas a C-terminal nonamyloidogenic fragment of 14 kilodaltons (kDa) was retained within the cell. Interestingly, thyroid epithelial cells also contained larger C-terminal APP fragments of 21, 35, and 41 kDa. From the sizes of these fragments it could be deduced that they contained the entire amyloid beta sequence and were thus potentially amyloidogenic. The 41-kDa fragment was unique to thyroid cells. These fragments may be released into the circulation after thyroid cell damage. Increased/altered thyroid APP expression in familiar AD may induce alterations in thyroid epithelial cells and cell damage, and thus explain the frequent occurrence of thyroid autoimmunity in this disease.

Adult↗
PubMed1994

Hyperthermia inhibits proliferation and stimulates the expression of differentiation markers in cultured thyroid carcinoma cells.

In the last two decades hyperthermia has increasingly been used as adjuvant therapy for the treatment of malignant tumours. The effects of heat were therefore analysed on cultured thyroid epithelial cells from patients with thyroid cancer and from non-malignant control thyroids. Purified thyroid cells were subjected to heat treatment (42.5 degrees C; 90 min). After 24 h [3H]thymidine incorporation was assessed and the expression of heat shock protein 72 (hsp72), thyroglobulin, CD54 (ICAM-I) and MHC class-Il were analysed by immunofluorescence staining. Additionally mRNA analysis was performed by Northern blotting. Whereas hyperthermia inhibited the proliferation of thyroid cells, it significantly increased the expression of hsp72, thyroglobulin, CD54 and HLA-DR (P < 0.05). Our results suggest that hyperthermia may suppress growth while supporting differentiation and immune recognition in thyroid cancer. It may therefore be beneficial as a treatment for patients with thyroid carcinoma.

Adenocarcinoma, Follicular↗
PubMed1994

Interferon gamma and iodide increase the inducibility of the 72 kD heat shock protein in cultured human thyroid epithelial cells.

The 72 kD heat shock protein (hsp 72) has been postulated to play a role in the development of autoimmune disease and has been shown to be overexpressed in the Graves' disease thyroid gland. The expression and modulation of the 72 kD heat shock protein were therefore studied in cultured human thyroid epithelial cells (TEC). TEC from normal thyroid tissue as well as from non-toxic goitres, thyroid adenomas and Graves' disease thyroids were analysed by Western blotting. Potential modulatory effects of heat shock treatment, TSH, IFN gamma, different serum supplements, sodium iodide and sodium selenite were investigated. Hsp 72 was detectable in cells from all tissue types under basal culture conditions and, at increased concentrations, after heat shock treatment. Quantitative evaluation of Western blotting results by densitometer scanning revealed that hsp 72 concentrations were identical in TEC from normal and diseased thyroids. IFN gamma increased the expression of hsp 72 under basal culture conditions as well as after heat shock treatment. TSH had no effect. Sodium iodide did not affect hsp 72 under basal culture conditions, but augmented the susceptibility of TEC to the effect of heat shock treatment. In contrast, sodium selenite had no effect on the expression of hsp 72. These results demonstrate that local as well as environmental factors may facilitate the induction of hsp 72 in TEC. This may be an important factor for the initiation and progression of thyroid autoimmunity. The stimulatory effect of iodide on hsp induction may also provide an explanation for the frequent occurrence of thyroid autoimmune diseases after iodine exposure.

Adenoma↗
PubMed1994

Long-term in vitro growth of human T cell clones: can postmitotic 'senescent' cell populations be defined?

The long-term in vitro growth characteristics of peripheral, nonspecifically expanded T cell clones from young (< 30 years old) and old (> 65 years old) Senieur-protocol compatible healthy blood donors were compared. Additionally, T cell clones derived from the sites of autoimmune events were studied. Until the 6th week in culture all clones showed a progressive increase in cell number. CD25 expression and proliferation in response to stimulation with recombinant IL-2 remained stable. Staining of DNA fragments with propidium iodide, however, revealed a small percentage of apoptotic cells. After 7-12 weeks in culture a rapid decrease in cell numbers accompanied by a striking increase in the number of apoptotic cells was noted in all peripheral clones. Although CD25 was still present on almost 100% of the cells, receptor density and proliferative response to IL-2 were greatly reduced. After a maximum of 14 weeks in culture, corresponding to 29 population doublings (PD), all peripheral T cell clones had died. No difference was noted between CD4 and CD8 T cell clones, but clones from old donors tended to have a shorter lifespan and a lower number of PD than clones from young persons (n.s.). Interestingly, T cells from autoimmune lesions had a longer lifespan and a higher number of PD than peripheral T cell clones (p < 0.01). In contrast to peripheral T cell clones, which died almost immediately after reaching the end of their proliferative capacity, a small but stable nondividing cell population could be distinguished in autoimmune clones.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1994

Retrobulbar T cells from patients with Graves' ophthalmopathy are CD8+ and specifically recognize autologous fibroblasts.

Graves' ophthalmopathy is an autoimmune condition characterized by T cell infiltration of the retrobulbar tissue. Phenotypic and functional analysis of these infiltrating cells may provide insight into the pathogenesis of the disease. IL-2-responsive cells were therefore grown out of the retrobulbar tissue from two patients with severe Graves' ophthalmopathy undergoing orbital decompression surgery, and six T cell lines were established and characterized. They consisted predominantly of CD8 + CD45RO+ cells and secreted IL-4, IFN-gamma, and IL-10 upon activation. When screened for their antigen reactivity, all lines proliferated in response to stimulation with autologous retrobulbar fibroblasts in an HLA class I-restricted manner, but did not recognize autologous peripheral blood mononuclear cells, crude eye muscle extract, allogeneic cells, or purified protein derivate of Mycobacterium tuberculosis. In contrast, PBMC from the same patients responded readily to purified protein derivate of Mycobacterium tuberculosis and allogeneic PBMC, but did not recognize autologous fibroblasts. Interestingly, only one of the six retrobulbar T cell lines displayed cytotoxicity towards its specific target cell population. These results suggest that the retrobulbar fibroblasts are a major T cell target in Graves' ophthalmopathy. Pronounced cytokine production in the absence of target cell cytotoxicity may explain fibroblast proliferation, glycosaminoglycan secretion, and secondary eye muscle enlargement in this condition.

Adult↗
PubMed1993

Stimulation of human thyroid growth via the inhibitory guanine nucleotide binding (G) protein Gi: constitutive expression of the G-protein alpha subunit Gi alpha-1 in autonomous adenoma.

The alpha subunits of the stimulatory and inhibitory G proteins, Gs alpha and Gi alpha, activate transmembrane-signaling systems involved in the control of cell proliferation. We have investigated the pattern of expression of Gi alpha subtypes and Gi alpha-mediated proliferative responses in the human thyroid. Human thyroid membranes contain two subtypes of Gi alpha, Gi alpha-1 and Gi alpha-2, as assessed by using specific antibodies. The expression of Gi alpha-1 is under tight control by thyrotropin in vivo and in primary cultures of thyroid epithelial cells. In contrast, Gi alpha-1 is expressed in the absence of thyrotropin in thyroid autonomous adenoma, an endocrine-active tumor, and its levels are not regulated by thyrotropin in thyroid epithelial cells prepared from these tumors. If thyroid epithelial cells are treated with pertussis toxin to block signal transduction via Gi, the mitogenic response to serum factors is reduced. These observations demonstrate that Gi subtypes transmit growth stimuli in the human thyroid. The constitutive expression of Gi alpha-1 in autonomous adenoma may allow for the unregulated stimulation of thyroid cell proliferation by a yet unidentified signaling pathway and, thus, be causally related to autonomous growth of thyroid cells.

Adenoma↗
PubMed1993

T-T cell interactions in patients with endocrine autoimmunity. Definition of antiergotypic T lymphocytes.

T-T cell interactions are known to be of importance in the generation of immune responses and have been postulated to play a role in autoimmunity. Antiergotypic T lymphocytes are cells, which react with other activated T cells, which they may consecutively neutralize. Antiergotypic T cells have been described to play a role in animal models of autoimmunity and have been found in patients with rheumatoid arthritis. It was the aim of the present study to analyse, whether antiergotypic T cells were also present in the blood of patients with endocrine autoimmunity and to characterize them in vitro. We found that peripheral blood mononuclear cells from patients with Graves' disease, Hashimoto's thyroiditis and Diabetes mellitus show a pronounced proliferative response, when stimulated with autologous T cell lines. This response is dependent on the state of activation of the stimulator cell population, but is independent of its phenotype and is not MHC restricted. In contrast to normal control cells PBMC from patients with endocrine autoimmune disorders respond better to autologous T lymphocytes, than to allogeneic T cells and to autologous E- monocytic cells. T cells responsive to activated autologous T cell lines can also be expanded from PBMC. They may be CD4+ or CD8+ and recognize autologous T cells in the presence of autologous PBMC as feeder cells. These results suggest the presence of a T-T cell network in patients with endocrine autoimmune disease, which may have an important regulatory role in the disease process.

Adult↗
PubMed1993

Possible role of human foamy virus in Graves' disease.

Human foamy virus (HFV) is a member of the retroviral family of Spumaretrovirinae. In addition to the three retroviral structural genes, gag, pol and env, HFV also contains regulatory sequences, called bel. Foamy viruses have been previously associated with human thyroid disease, notably DeQuervain's thyroiditis. In indirect immunofluorescence tests we have demonstrated the reactivity of the thyroid glands of 7/7 patients with Graves' disease and antibodies to HFV gag proteins. No reactivity was observed with antibodies to pol, env and bel proteins. Nine thyroids of patients with struma parenchymatosa, 4 with follicular carcinoma and 2 normal thyroids were negative throughout. From the thyroids of 5 patients with Hashimoto's disease, 4 were negative and 1 showed a single small focus of anti-gag antibody reactivity. The uniform immunofluorescent staining was restricted to the basal and lateral intercellular areas between the thyroid epithelial cells. Extension of these studies to the retrobulbar tissue of 1 Graves' disease patient with malignant exophthalmus revealed positive staining with anti-gag antibodies of fibroblasts and fat cells but not eye muscles. Furthermore, we were successful in establishing several T-cell lines derived from the retrobulbar tissue of this patient. They were CD8+ and proliferated, in contrast to peripheral blood cells, upon cocultivation with autologous retroorbital fibroblasts. It remains to be determined whether these observations are of relevance in the pathogenesis of Graves' disease.

Graves Disease↗
PubMed1993

Suramin affects human peripheral blood mononuclear cells in vitro: inhibition of T cell growth and modulation of cytokine secretion.

Suramin, a polyanionic compound, which has been in clinical use for the treatment of African trypanosomiasis for several decades, has recently been introduced in clinical oncology. Its effects on the immune system seemed therefore of interest. In the present study we tried to elucidate in vitro how suramin affected different functions of human peripheral blood mononuclear cells (PBMC). Suramin suppressed the proliferation of PBMC in response to various stimuli, including OKT3, phytohemagglutinin (PHA), phorbolmyristate-acetate (PMA) and ionomycin, purified protein derivate of Mycobacterium tuberculosis (PPD) and antibodies against CD2. It also inhibited the binding of monoclonal antibodies to T cell surface antigens. This effect was not dependent on the isotype of the antibody, but seemed to be highly epitope-specific. Among a panel of antibodies against one antigen, only a few were affected by the compound. Whereas the binding of Leu3a and OKT3 was for instance fully suppressed by suramin, OKT4 and Leu4 binding was only slightly affected. Suramin also decreased the expression of T cell surface molecules such as CD2, CD25 and CD4 in preactivated PBMC and had pronounced effects on cytokine production. Interestingly the compound had adverse regulatory effects on different cytokines. Whereas the secretion of interferon-gamma was completely suppressed by suramin, interleukin-2 (IL-2) and IL-4 production was stimulated. These results demonstrate that suramin affects T cell function in multiple different ways. This will have to be considered, when suramin is used in the treatment of cancer patients.

Adult↗
PubMed1993

Do heat shock proteins play a role in Graves' disease? Heat shock protein-specific T-cells from Graves' disease thyroids do not recognize thyroid epithelial cells.

Thyroid-derived T-cells from patients with Graves' disease were analyzed for their reactivity to recombinant heat shock proteins (hsp) and autologous thyroid epithelial cells (TEC). Five of six uncloned T-cell lines responded to stimulation with recombinant mycobacterial 71-kilodalton (kDa) hsp and cross-reacted with the corresponding amoebial and human proteins. Only one line reacted with recombinant 65-kDa hsp. Thyroid-derived T-cell lines also showed a proliferative response to TEC, which could be increased in four of the lines, when hsp expression was induced in thyroid cells by heat stress before the initiation of coculture. Clonal specificity analysis of thyroid-derived T-cell clones, however, demonstrated that distinct T-cells were responsible for the recognition of recombinant hsp and TEC. None of the clones responsive to recombinant hsp recognized TEC, whereas TEC-responsive clones did not react with recombinant hsp. Interestingly, the response of the majority of TEC-reactive clones could be dramatically increased when heat-shocked TEC were used as stimulator cells. These results suggest that T-cells specific for hsp of the 70- or 60-kDa families do not recognize TEC in the autoimmune thyroid gland. Heat shock-inducible proteins may, however, still play a role in the autoimmune process by facilitating the presentation of thyroid-specific autoantigen(s) to autoreactive T-cells.

Adult↗