Biomedical subjects

S Seiter

Publications and source records attributed to S Seiter.

34 records · Page 2Linked to original sources

PubMed1999

Successful treatment of progressive vitiligo with high-dose intravenous methylprednisolone 'pulse' therapy.

We report on the successful therapy of rapid progressive generalized vitiligo in a 24-year-old woman. After intravenous injection of 500 mg of methylprednisolone on 3 consecutive days, the disease progression was stopped and repigmentation was induced. The treatment was repeated monthly and after 6 cycles, repigmentation was achieved on vast parts of most vitiligo lesions. The treatment was well tolerated by the patient, and no side effects were noted. We conclude that high-dose glucocorticoid pulse therapy may represent a therapeutic alternative in selected patients with generalized rapid progressive vitiligo.

Adult↗

PubMed1999

CD2-mediated CD59 stimulation in keratinocytes results in secretion of IL-1alpha, IL-6, and GM-CSF: implications for the interaction of keratinocytes with intraepidermal T lymphocytes.

Normal epidermal keratinocytes are here shown to express membrane-associated complement inhibitory protein CD59 in vitro that protects keratinocytes from damage by complement because preincubation with blocking antibodies to CD59 renders the cells susceptible to complement mediated lysis. CD59 expression in keratinocytes is constitutive and not modulated by inflammatory cytokines, phorbol myristate acetate (PMA), and a number of other agents tested. Antibody mediated cross-linking of CD59, however, revealed an additional function of CD59: keratinocytes in vitro are activated to secrete the cytokines IL-1alpha, IL-6, and GM-CSF. CD59 mediated induction of these cytokines is regulated at the transcriptional level. Binding of keratinocytes to HL60 cells that express CD59 ligand CD2 induced the same pattern of secreted cytokines whereas binding to CD2-negative HL60 cells did not. Induction of cytokine secretion was completely blocked by preincubation of keratinocytes with both anti-CD58 and anti-CD59 antibodies together. The results demonstrate that CD2-mediated CD59 stimulation in human keratinocytes leads to synthesis of a particular set of cytokines implying a potential activation pathway in the interaction of keratinocytes with intraepithelial CD2+ T cells.

Antibodies, Blocking↗

PubMed1999

CD44 variant isoforms on blood leukocytes in chronic inflammatory bowel disease and other systemic autoimmune diseases.

We have described recently that TNBS-induced colitis, an animal model of chronic inflammatory bowel disease (IBD), can be cured by treatment with anti-CD44v7. This finding led us to evaluate whether CD44v7 may be of functional importance in patients with IBD. Expression of CD44 variant isoforms (CD44v) has been evaluated on PBMC of 46 patients with IBD, 43 patients with autoimmune diseases not affecting the gastrointestinal tract, 26 patients with nonautoimmune disease, and 24 healthy donors. In all groups, expression of CD44v on freshly harvested PBMC was not above or was borderline above background levels. After in vitro stimulation, expression of CD44 standard (CD44s) and CD44v6 was strongly up-regulated. Exclusively on PBMC of patients with autoimmune disease, high expression of CD44v3 and CD44v7 was observed. CD44v3 and CD44v7 were mainly expressed on subsets of CD4+ lymphocytes, B cells, and monocytes; CD44v6 was predominantly detected on CD4+ and CD8+ cells. Considering functional activity, CD44v7 apparently exerted a dual effect. After culturing PBMC in the presence of anti-CD44v7, a higher percentage of cells produced IL-10. This was irrespective of whether the PBMC were derived from healthy donors or from patients with autoimmune disease or IBD. On the other hand, PBMC of all donors proliferated upon cross-linking of CD3 and CD44s or CD3 and CD44v6. Instead, costimulatory activity of CD44v7 was seen only in PBMC of patients with autoimmune disease and IBD. Because expression and function of CD44v7 in patients with systemic autoimmune disease and IBD have been much like the ones in mice suffering of TNBS-induced colitis, it is tempting to speculate that blockade of CD44v7 could also be of therapeutic relevance in the human diseases.

Adult↗

PubMed1998

Cloning and functional characterization of a new phosphatidyl-inositol anchored molecule of a metastasizing rat pancreatic tumor.

We have described recently a panel of metastasis-associated antigens expressed on a rat pancreatic tumor. One of these molecules, recognized by the monoclonal antibody C4.4 and named accordingly C4.4A, was under physiological conditions expressed only in the gravid uterus and on epithelial of the upper gastrointestinal tract. The cDNA of the antigen has been isolated and cloned. The 1,637 b cDNA codes for a 352 amino acid long glycosylphosphatidyl-inositol (GP) anchored molecule, whose molecular weight varies in different cells between 94-98 kD according to the degree of N- and O-glycosylation. Data base searches have revealed a low degree of homology to the receptor for the plasminogen activator (uPAR). After intrafootpad and intravenous application of C4.4A transfected and mock-transfected tumor cells, an increased number of lung nodules was detected with the former, whereby the individual metastatic nodules amalgamated without any encapsulation of the tumor tissue. Furthermore, C4.4A is involved in adhesion to laminin and, although transfection of a non-metastasizing tumor line with the molecule was not sufficient, constitutively C4.4A-positive tumor cells penetrated through matrigel. This process could be completely prevented by C4.4. Finally, we could demonstrate that uPA, albeit weakly, bound to the C4.4A molecule. In view of the observed influence of C4.4A on metastasis formation and matrix penetration it is tempting to speculate that this newly described metastasis-associated molecule may exert functional activity similar to the uPAR, i.e. via activation of matrix degrading enzymes. By the very restricted expression of the molecule in the adult organism, modulation of C4.4A could well be of therapeutic interest.

Amino Acid Sequence↗

PubMed1998

Down-modulation of host reactivity by anti-CD44 in skin transplantation.

BACKGROUND: A major goal in transplantation medicine is to achieve donor-specific tolerance while sustaining unaltered immunoreactivity toward donor-independent stimuli. Pretransplant immunization and concomitant blockade of costimulatory molecules may be one way to achieve this goal. We investigated whether transplant acceptance could be achieved by sensitization with semiallogeneic blood and blockade of CD44s (standard isoform) or CD44v6 (variant exon 6), since the adhesion molecule CD44 is known to function as a costimulatory molecule in T-cell activation. METHODS: Immunoregulatory regimens were examined in BDX rats that had received full-thickness (DA x BDX)F1 skin grafts by controlling graft acceptance and immunoreactivity. RESULTS: When BDX rats received full-thickness (DA x BDX)F1 skin grafts together with either anti-CD44s or anti-CD44v6, graft rejection was delayed, but none of the animals accepted the graft. An analysis of immunoreactivity revealed reduced numbers of infiltrating lymphocytes in anti-CD44s- as well as anti-CD44v6-treated rats. Expansion of donor-specific helper and cytotoxic T cells was particularly impaired in anti-CD44v6-treated rats. The effect of anti-CD44s could not be intensified by presensitization with donor-derived blood. However, when rats received anti-CD44v6 concomitantly with presensitization, 75% permanently accepted the graft and 50% accepted a second graft provided they were continuously treated with anti-CD44v6 and received a low dose of cyclosporine (CsA) during the first weeks after grafting. The frequency of graft-reactive helper T cells was reduced to less than 10% of the level in controls, and cytotoxic T cells could hardly be detected. CONCLUSION: According to the in vivo and the vitro analyses of the graft and the draining lymph nodes, anti-CD44s blocked homing of activated lymphocytes into the graft, while anti-CD44v6 inhibited clonal expansion of donor-specific T cells. Suppression by anti-CD44v6 apparently functioned distinctly to cyclosporine and was most effective in combination with presensitization. Since expression of CD44v6 on lymphocytes is restricted to a short period during lymphocyte activation, anti-CD44v6 treatment could lead to a quite specific immunosuppression during a limited time period.

Animals↗

PubMed1998

Association between the rat homologue of CO-029, a metastasis-associated tetraspanin molecule and consumption coagulopathy.

Recently, we have described a panel of metastasis-associated antigens in the rat, i.e., of molecules expressed on metastasizing, but not on nonmetastasizing tumor lines. One of these molecules, recognized by the monoclonal antibody D6.1 and named accordingly D6. 1A, was found to be abundantly expressed predominantly on mesenchyme-derived cells. The DNA of the antigen has been isolated and cloned. Surprisingly, the gene product proved to interfere strongly with coagulation. The 1.182-kb cDNA codes for a 235-amino acid long molecule with a 74.2% homology in the nucleotide and a 70% homology in the amino acid sequence to CO-029, a human tumor-associated molecule. According to the distribution of hydrophobic and hydrophilic amino acids, D6.1A belongs to the tetraspanin superfamily. Western blotting of D6.1A-positive metastasizing tumor lines revealed that the D6.1A, like many tetraspanin molecules, is linked to further membrane molecules, one of which could be identified as alpha6beta1 integrin. Transfection of a low-metastasizing tumor cell line with D6.1A cDNA resulted in increased metastatic potential and provided a clue as to the functional role of D6.1A. We noted massive bleeding around the metastases and, possibly as a consequence, local infarctions predominantly in the mesenteric region and all signs of a consumption coagulopathy. By application of the D6.1 antibody the coagulopathy was counterregulated, though not prevented. It has been known for many years that tumor growth and progression is frequently accompanied by thrombotic disorders. Our data suggest that the phenomenon could well be associated with the expression of tetraspanin molecules.

Adenocarcinoma↗

PubMed1998

CD44 variant isoform expression in a variety of skin-associated autoimmune diseases.

CD44 variant isoforms are frequently expressed on tissue-infiltrating lymphocytes. By the high incidence of autoimmune reactions of the skin and aiming at new strategies of therapeutic intervention, we became interested in evaluating the CD44 isoform expression profile in autoimmune reactions of the skin. Expression of CD44s, CD44v3, v5, v6, v7, v7-v8, and v10 was evaluated in 55 biopsies of lupus erythematosus, bullous pemphigoid, vasculitis, morphea, and pemphigus vulgaris. Biopsies did not contain CD44v5-, CD44v6-, CD44v7-, or CD44v7-v8-positive leukocytes. Staining with anti-CD44v10 was seen in vasculitis and occasionally in lupus erythematosus, morphea, and bullous pemphigoid. All biopsies contained CD44v3(+) leukocytes, the percentage of CD44v3(+) leukocytes being increased in autoimmune infiltrates with the exception of pemphigus vulgaris. CD44v3 was expressed by CD4(+) cells as well as by part of CD8(+) cells, Langerhans cells, and monocytes. Vascular endothelium also contained CD44v3(+) cells. Only monocytes expressed CD44v10. We assume that CD44v3 and CD44v10 may be targeting leukocytes toward the skin or allow for their retention and expansion via binding of cytokines and chemokines harbored by activated, skin-associated endothelium or provided by cells surrounding the infiltrate. The absence of CD44v6, frequently associated with lymphocyte activation, appears to be a peculiarity of skin-infiltrating leukocytes.

Autoimmune Diseases↗

PubMed1997

Functional activity of murine CD44 variant isoforms in allergic and delayed type hypersensitivity.

There is ample evidence that the family of CD44 glycoproteins is involved in homing, maturation and activation of lymphocytes. Furthermore, recent evidence suggests that CD44 splice variants are particularly involved in the process of lymphocyte activation whereby it was hypothesized that different isoforms may fulfill distinct functions. We here addressed the question of CD44v6 and CD44v7 being involved in TH1 and TH2 reactions using as model systems for TH1 activation a TNBS-induced colitis and a DNFB-induced DTH reaction and for TH2 activation a FITC-induced allergic dermatitis. With the exception of a small subpopulation of lymphocytes in Peyer's patches, expression of neither CD44v6 nor CD44v7 was noted in the absence of an antigenic stimulus. Both CD44 variant exons are transiently detected on T lymphocytes during mounting of an immune response. In vitro studies revealed that antibodies against both CD44v6 and CD44v7 inhibited lymphocyte proliferation and cytokine production. Based on these findings the efficiency of anti-CD44v6 and anti-CD44v7 treatment was evaluated in vivo in TH1 and TH2 dependent autoimmune and DTH reactions. Anti-CD44v7 completely abrogated development of a death promoting colitis and anti-CD44v6 as well as anti-CD44v7 significantly mitigated the DNFB-induced, TH1-mediated DTH reactions, while only anti-CD44v7 interfered with a FITC-induced, TH2-mediated allergic contact dermatitis. The in vitro analysis of cytokine producing cells supported the assumption. In conclusion, it could be demonstrated that CD44v6 and CD44v7 are differentially involved in TH1 and TH2 activation and, most importantly, a TH1-mediated autoimmune disease could be prevented by local application of anti-CD44v7.

Animals↗

PubMed1997

CD44v10 expression in the mouse and functional activity in delayed type hypersensitivity.

We have described recently that expression of CD44 exon v10 (CD44v10) is down-regulated upon metastasis of squamous cell carcinoma, whereas it is up-regulated in skin metastases of malignant melanoma. The striking regulation of CD44v10 prompted us to generate a murine CD44v10-specific monoclonal antibody to define expression and possible functions of this particular CD44 variant isoform. In the mouse, expression of exon v10 was restricted to basal layers of the epidermis and squamous epithelium of the oral cavity, the esophagus, the omasum, glandular epithelium of the submandibular and the uterine gland, as well as subpopulations of bone marrow cells and activated lymphocytes. Expression started late during development, e.g., was not observed before day 16 of gestation and there was no evidence for developmental regulation of CD44v10 expression. Functional in vivo studies revealed that anti-CD44v10 had no effect on wound healing but inhibited edema and granuloma formation in delayed type hypersensitivity (DTH). Furthermore, lymphocyte-monocyte interactions could be inhibited by anti-CD44v10. Because a CD44v10 transfected tumour line did not show any distinct pattern of cell-matrix or cell-cell adhesion, the data point toward an involvement of CD44v10 in cell migration, possibly by acting as a target structure for cytokines/chemokines provided by the contacted partner cell.

Animals↗

PubMed1997

Detection of circulating melanoma cells by specific amplification of tyrosinase complementary DNA is not a reliable tumor marker in melanoma patients: a clinical two-center study.

PURPOSE: Recently, the reverse-transcription polymerase chain reaction (RT-PCR) of tyrosinase messenger RNA (mRNA) was reported to be a useful tool for the detection of circulating tumor cells in the peripheral blood of melanoma patients. Our aim was to evaluate critically the diagnostic value of this marker by investigating a significant number of patients in different stages of the disease in a two-center study. PATIENTS AND METHODS: Different techniques of blood collection, RNA isolation, and RT-PCR were compared, and the detectability of tyrosinase mRNA was tested using nine different melanoma cell lines. The sensitivity of the method was confirmed by blood spiking experiments and the specificity by restriction enzyme analysis. Subsequently, a total of 153 blood samples from 137 individuals (30 healthy subjects, five basal cell carcinoma, and 102 melanoma patients) were investigated. RESULTS: The detection level of melanoma cells differed between the cell lines tested. However, we could reproducibly detect single melanoma cells by spiking whole blood samples from healthy volunteers. One of 43 patients with primary melanoma (2.3%), zero of 15 patients with regional metastasis (0%), and 12 of 44 patients with advanced disease (27.3%) were found to be RT-PCR positive. All blood samples obtained from controls and patients with basal cell carcinoma were tyrosinose mRNA negative. CONCLUSION: Our data support the recent doubts that the detection of circulating tumor cells in melanoma patients using the tyrosinase mRNA RT-PCR is not sensitive enough to be used either as a melanoma progression marker in early stages of the disease or to monitor therapy in advanced stages of the disease.

Biomarkers, Tumor↗

PubMed1997

Transient absence of CD44 expression and delay in development by anti-CD44 treatment during ontogeny: a surrogate of an inducible knockout?

Because the lack of some adhesion molecules induced by site-directed mutagenesis has been described to be lethal, whereas the lack of others apparently has no effect, we were interested in seeing whether the developing organism might gradually adapt to the absence of adhesion molecules. Therefore, we chose a form of transient interference by i.v. injection of antibody into pregnant rats. As a model, we selected CD44, which has been reported to play a key role during embryogenesis. Rats received either an antibody recognizing an epitope on the CD44 standard isoform (CD44s) or on exon v6 (CD44v6). In the presence of anti-CD44s, delivery was frequently delayed, and intrauterine abortions were often observed. The fetuses were smaller, particularly the anlage of the hair follicle of the whisker, and the formation of alveoli in the lung, of the tubular system of the kidney, and of villi in the gut was delayed. The development of fetuses receiving anti-CD44v6 was hampered until days 16-18 of gestation. Immunodetection revealed a weaker expression of the target molecules at the implantation site and the complete absence of CD44s and CD44v6 expression in fetal tissue until day 12. During the late stages of gestation, the expression pattern of CD44 resembled that of 2-3-day-younger fetuses of untreated rats. Interestingly, degradation of hyaluronate was also delayed, particularly in the kidney. Thus, the diaplacental antibody passage was very efficient and should make it possible to obtain a clearly defined and differentiated concept of the requirements for the CD44 molecule during ontogeny and also for fail-safe mechanisms. Both experiences may be missed in the knockout proper.

Animals↗

PubMed1996

Expression of CD44 splice variants in squamous epithelia and squamous cell carcinomas of the head and neck.

Splice variants of the adhesion molecule CD44 have been described as essential for the lymphatic spread of rat tumour cells and are claimed to be involved in the metastatic spread of several human tumours. Immunohistochemistry has been used to analyse the expression pattern of CD44 standard (CD44s) and variant (CD44v) isoforms in normal and dysplastic squamous epithelia, as well as in primary and metastatic squamous cell carcinomas (SCCs), which spread predominantly by way of the lymphatic system. Frozen sections of squamous epithelia and of squamous cell carcinomas were stained with a panel of monoclonal antibodies recognizing epitopes of CD44s as well as of the variant exons v5, v6, v7, v7-v8, and v10. The stratum basale and stratum suprabasale of squamous epithelia stained with all antibodies; the stratum spinosum stained with anti-CD44v5, anti-CD44v6, anti-CD44v7-8 and anti-CD44v10; the lower layers of the stratum corneum stained with anti-CD44v5. This expression profile was seen in epithelia of the lip, the tongue, the gingiva, the hard palate, the floor of the mouth, the buccal mucosa, and the pharynx. The same pattern of expression was also noted in dysplastic epithelia, but expression of the variant exons v7, v8, and v10 was significantly downregulated in primary squamous cell carcinomas and was not detected at all in the majority of metastasis-derived specimens. Expression of CD44v5 and CD44v6, on the other hand, was mainly unaltered. Thus, epithelial cell layers representing different stages of differentiation express distinct sets of CD44 variant isoforms, where especially exons v8-v10 might be required for the maintenance of the structural integrity of squamous epithelium. Downregulation of these exons on tumour cells could indicate that they are irrelevant for tumour progression or may even hamper infiltration of surrounding tissue or of lymphatics.

Adult↗

PubMed1996

Expression of CD44 splice variants in human skin and epidermal tumours.

Splice variants of the adhesion molecule CD44 (CD44v) are important in the lymphatic spread of rat carcinoma cells. In several human tumours expression of CD44v correlates with tumour progression. However, little is known about the physiological functions of distinct variant exons. Here we report on the immunohistological evaluation of CD44 expression in normal human skin and epidermal tumours which do not metastasise, or do so vary rarely. Frozen tissues were stained with a panel of monoclonal antibodies, recognizing epitopes of the CD44 standard isoform, as well as of variant exons v5, v6, v7, v7-v8 and v10. Stratum basale and spinosum as well as the root shaft of hairs reacted strongly with the whole panel of anti-CD44 antibodies. Stratum corneum, acinar cells of sebaceous and eccrine sweat glands stained with anti-CD44v5, anti-CD44v6 and anti-CD44v7, but not with anti-CD44v10, the latter recognizing the "epithelial isoform" (CD44v8-v10) of CD44. Ductal cells of glands and apocrine glands did not express CD44v. Compared with its expression in normal human skin, CD44v expression was reduced in basal cell carcinoma and squamous cell carcinoma of the skin. This was particularly true of CD44v10. The expression of CD44v in normal skin and dermal appendages indicates that not all combinations of variant exons are involved in tumour progression. Since the epithelial isoform is particularly downregulated in basal cell carcinoma and squamous cell carcinoma of the skin, it is unlikely that exons v8-v10 play a role in tumour progression. Rather, they may be of functional importance in maintenance of the epidermal structure.

Animals↗

PubMed1996

Expression of CD44 variant isoforms in malignant melanoma.

In a variety of human tumors, expression of splice variants of the adhesion molecule CD44 (CD44v) has been described as correlating with tumor progression. Here, we report on the expression of CD44v in melanocytes, nevi, primary melanomas, and cutaneous and lymph node metastases. Thirteen nevi, 65 primary melanomas of varying thickness, 39 cutaneous and 15 lymph node metastases, and melanocytes and a panel of melanoma lines were tested for surface expression of the standard form of CD44 and the variant exons v5, v6, v7, v7-v8, and v10 by immunohistology or fluorescence-activated cell sorting. Melanocytes did not express any variant isoform of CD44. However, nevi, as well as primary melanoma and melanoma metastases, stained to a varying degree with anti-CD44v5, anti-CD44v7-v8, and anti-CD44v10. Exons v6 and v7 were not detected on any of these tissue specimens. Compared with nevi, expression of exon v10 was up-regulated in thick primary tumors and skin metastases. Lymph node metastases displayed elevated levels of exon v5. Expression of CD44v in melanoma lines (n = 20) differed, inasmuch as many lines did not express variant isoforms; in particular, exon v10. Interestingly, however, the few CD44v5-positive melanoma lines metastasized in the nu/nu mouse. Because benign as well as malignant growth of melanocytes was accompanied by expression of CD44 variant isoforms, a linkage between expression of CD44 variant isoforms and malignant transformation or tumor progression was excluded. Considering the function of distinct isoforms, one might speculate that expression of exon CD44v5, which was up-regulated in lymph node metastases compared with nevi and primary melanoma, provided a growth stimulus. Exon v10 is present at high density in epidermal cells. The de novo expression of this exon in nevi and the increased expression in thick melanoma and skin metastases would be in line with the assumption of an anchoring advantage in the surrounding epidermal tissue.

Animals↗

PubMed1993

Prevention of tumor metastasis formation by anti-variant CD44.

A splice variant of CD44 (CD44v) originally discovered on metastases of a rat pancreatic adenocarcinoma (BSp73ASML) has been shown by transfection to confer metastatic behavior to nonmetastatic tumor cells (Günthert U., M. Hofmann, W. Rudy, S. Reber, M. Zöller, I. Haussmann, S. Matzku, A. Wenzel, H. Ponta, and P. Herrlich. 1991. Cell. 65:13). A monoclonal antibody (mAb), 1.1ASML, to the metastasis-specific domain of the CD44v molecule retards growth of lymph node and lung metastases of the metastatic tumor line BSp73ASML, and can efficiently prevent formation of metastases by the transfected line. The antibody is only effective when given before lymph node colonization. Anti-CD44v does not downregulate the expression of CD44v, and prevention of metastatic growth by anti-CD44v is not due to activation of any kind of immune defense. We suggest that the mAb interferes with proliferation of metastasizing tumor cells in the draining lymph node, most probably by blocking a ligand interaction. The interference with metastatic spread will greatly facilitate the exploration of the function of CD44v and, in particular, may also open new strategies for the therapy of human metastases.

Animals↗

PubMedDate not supplied

Multiple granular cell tumors and growth hormone deficiency in a child.

Granular cell tumor is an uncommon benign tumor occurring on the skin as a single nodule. Multiple tumors are very rare, particularly in children. We describe a child with multiple granular cell tumors on the skin in association with growth hormone deficiency. The occurrence of multiple granular cell tumors in association with other clinical manifestations in childhood is discussed.

Child↗