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Biomedical subjects

Thomas Krieg

Publications and source records attributed to Thomas Krieg.

86 records · Page 5Linked to original sources
PubMed2002

Distinct in vivo expression patterns of survivin splice variants in renal cell carcinomas.

Survivin, a novel member of the inhibitor of apoptosis protein (IAP) family, reduces the susceptibility of tumor cells to proapoptotic stimuli, thereby promoting tumor cell survival during tumor progression and treatment with anticancer drugs. Recently, we identified 2 novel alternative splice variants of survivin, survivin-2B and survivin-Delta Ex3, which differ in their antiapoptotic properties. Survivin-2B has lost its antiapoptotic potential and may act as a naturally occurring antagonist of antiapoptotic survivin and survivin-Delta Ex3. Because the in vivo expression of these splice variants in human cancer has not been analyzed so far, 57 renal cell carcinomas (RCCs) were explored using quantitative reverse transcriptase polymerase chain reaction. We found that all RCCs express survivin-Delta Ex3, survivin-2B and survivin, the latter being the dominant transcript. When we compared early and intermediate stages with late stages of clear cell RCCs, no significant changes in the expression levels of survivin and survivin-Delta Ex3 became evident. However, a significant decrease was observed for the mRNA ratio between survivin-2B and survivin in late tumor stages (p = 0.036). Chromophilic/papillary RCCs, which are known to be less aggressive than clear cell RCCs, did not show significantly lower expression levels of antiapoptotic survivin and survivin-Delta Ex3, compared with stage-adjusted clear cell RCCs. Our study demonstrates for the first time in vivo expression of functionally different survivin variants and suggests a role of these survivin splice variants in the progression and clinical behavior of human RCCs.

Alternative Splicing↗
PubMed2002

TNF-mediated inflammatory skin disease in mice with epidermis-specific deletion of IKK2.

The I kappa B kinase (IKK), consisting of the IKK1 and IKK2 catalytic subunits and the NEMO (also known as IKK gamma) regulatory subunit, phosphorylates I kappa B proteins, targeting them for degradation and thus inducing activation of NF-kappa B (reviewed in refs 1, 2). IKK2 and NEMO are necessary for NF-kappa B activation through pro-inflammatory signals. IKK1 seems to be dispensable for this function but controls epidermal differentiation independently of NF-kappa B. Previous studies suggested that NF-kappa B has a function in the growth regulation of epidermal keratinocytes. Mice lacking RelB or I kappa B alpha, as well as both mice and humans with heterozygous NEMO mutations, develop skin lesions. However, the function of NF-kappa B in the epidermis remains unclear. Here we used Cre/loxP-mediated gene targeting to investigate the function of IKK2 specifically in epidermal keratinocytes. IKK2 deficiency inhibits NF-kappa B activation, but does not lead to cell-autonomous hyperproliferation or impaired differentiation of keratinocytes. Mice with epidermis-specific deletion of IKK2 develop a severe inflammatory skin disease, which is caused by a tumour necrosis factor-mediated, alpha beta T-cell-independent inflammatory response that develops in the skin shortly after birth. Our results suggest that the critical function of IKK2-mediated NF-kappa B activity in epidermal keratinocytes is to regulate mechanisms that maintain the immune homeostasis of the skin.

Animals↗
PubMed2002

Integrin alpha 2-deficient mice develop normally, are fertile, but display partially defective platelet interaction with collagen.

The integrin alpha(2)-subunit was ablated in mice by targeted deletion of the ITGA2 gene. alpha(2)-Deficient animals develop normally, are fertile, and reproduce. Surprisingly, no obvious anatomical or histological differences were observed in mutant mice. Besides its significance in tissue morphogenesis, integrin alpha(2)beta(1) has been reported to play a major role in hemostasis by mediating platelet adhesion and activation on subendothelial collagen. To define its role in hemostasis, alpha(2)-deficient platelets were analyzed for their capacity to adhere to and aggregate in response to fibrillar or soluble collagen type I. We show that aggregation of alpha(2)-deficient platelets to fibrillar collagen is delayed but not reduced, whereas aggregation to enzymatically digested soluble collagen is abolished. Furthermore, alpha(2)-deficient platelets normally adhere to fibrillar collagen. However, in the presence of an antibody against GPVI (activating platelet collagen receptor), adhesion of alpha(2)-deficient but not wild type platelets is abrogated. These results demonstrate that integrin alpha(2)beta(1) significantly contributes to platelet adhesion to (fibrillar) collagen, which is further confirmed by the abolished adhesion of alpha(2)-deficient platelets to soluble collagen. Thus, alpha(2)beta(1) plays a supportive rather than an essential role in platelet-collagen interactions. These results are in agreement with the observation that alpha(2)beta(1)-deficient animals suffer no bleeding anomalies.

Animals↗
PubMed2002

Identification of activated matrix metalloproteinase-2 (MMP-2) as the main gelatinolytic enzyme in malignant melanoma by in situ zymography.

The involvement of extracellular matrix-degrading enzymes, such as matrix metalloproteinases and serine proteases, during tumour progression and metastasis is well established. In particular, the activation of pro-matrix metalloproteinase (MMP)-2 on the surface of malignant cells by membrane-bound MT1-MMP has been shown to contribute to the invasive abilities of various tumours. This study presents evidence that in tissue of malignant melanomas, increased effective gelatinolytic activity is mainly located at sites where melanoma cells interact with the surrounding extracellular matrix. Forty-one primary melanomas (30 superficial spreading and 11 nodular type) and six lymph node metastases were investigated by a modified technique of gelatin in situ zymography. This technique localizes areas of effective proteolytic activity within tissue sections. In 28/41 (68%) primary melanomas and in 6/6 (100%) metastases, considerable proteolysis was detected at the invading part of the tumour and especially at sites of tumour-stroma interactions, whereas no or only weak proteolytic activity was localized within the centres of solid nests of tumour cells. Zymographic analysis of extracts obtained from different areas of microdissected melanoma specimens identified activated MMP-2 as the enzyme responsible for this activity. Immunohistochemical analysis detected strong staining for MMP-2 and MT1-MMP, even in areas in which no proteolytic activity was found by in situ zymography, emphasizing the importance of more functional techniques for the investigation of balanced proteolytic systems. This technology makes it possible to draw conclusions regarding the balance between activated proteases and inhibitors, which are frequently found to be present together in close proximity in vivo.

Biopsy↗
PubMed2002

Defective laminin 5 processing in cylindroma cells.

Cylindromas are benign skin tumors occurring as multiple nodules characteristically well circumscribed by an excess of basement membrane-like material. To determine the molecular defects leading to extracellular matrix accumulation, the ultrastructural, immunological, and biochemical properties of cylindroma tissue and isolated cells were analyzed. In cylindromas, hemidesmosomes are reduced in number, heterogeneous and immature compared to the normal dermal-epidermal junction. Expression of the alpha6beta4 integrin in tumor cells is weaker than in basal keratinocytes of the epidermis. Moreover, although in the epidermis alpha2beta1-integrin expression is restricted to the basal cell layer, it is found in all neoplastic cells within the nodules. Laminin 5 is present throughout the whole thickness of the basement membrane-like zone whereas laminin 10 is restricted to the interface adjacent to the tumor cells. Furthermore, laminin 5 is not properly processed and most of the alpha3A and gamma2 laminin chains remain as 165-kd and 155-kd polypeptides, respectively. Mature laminin 5 is thought to be necessary for correct hemidesmosome and basement membrane formation and its abnormal processing, as well as the low expression of alpha6beta4 integrins, could explain the lack of mature hemidesmosomes. Together, the results show that multiple molecular defects, including alteration of laminin 5 and its integrin receptors, contribute to structural aberrations of the basement membrane and associated structures in cylindromas.

Antibodies↗
PubMed2002

Integrin expression in the dermis during scar formation in humans.

To evaluate changes leading to human wound reorganization we examined by immunohistochemistry the expression of several extracellular matrix (ECM) receptors (alpha2 chain of VLA-2, alpha3 chain of VLA-3, alpha6 chain of VLA-6, alphav, and beta1/beta3 chains of integrins) in a series of biopsies of human skin wounds healing by primary intention. The first time point investigated in this study was day 6 after injury, i.e. when a fibrin clot has been almost completely replaced by the granulation tissue. Gradual changes in integrin expression in granulation tissue and in the dermal scar were observed from the first time point investigated and were characterized by an up-regulation of alpha2beta1 complex, alphav integrin subunit, and beta1 integrin subunit. At day 27, the expression of the alpha2 chain of VLA-2 in the scar decreased. The expression of alphav and beta1 integrin subunits decreased but was still detectable by day 35. Vitronectin expression from day 7 onwards was also increased and colocalized to the area of the wounded dermis, and decreased by day 27. Our data suggests that, during the remodelling of the provisional matrix of the wound, dermal fibroblasts express transiently mainly alpha2 and alphav subunits of integrins associated with up-regulation of the beta1 subunit. It seems that up-regulation of some chains of integrins may be involved in the control of deposition of ECM components associated with wound healing.

Cicatrix↗
PubMed2002

Expression of matrilin-2 in human skin.

The extracellular matrix is composed of a large number of different modular proteins. Matrilin-2 is a newly described member of the protein superfamily with von Willebrand factor A-like modules. To examine the expression of matrilin-2 in human skin, the distribution of protein and mRNA was studied by immunohistochemistry and in situ hybridization. In addition, immunoblotting and real-time reverse transcription polymerase chain reaction were used to investigate the expression of matrilin-2 in keratinocyte and fibroblast cultures. In vivo, keratinocytes and fibroblasts were both found to express matrilin-2 mRNA and deposit the protein at the basal side of the dermal-epidermal basement membrane. Matrilin-2 molecules synthesized by the two cell types in vitro appeared to be processed differently by cell-associated proteases. Transcription of matrilin-2 mRNA in keratinocytes was enhanced by a diffusible factor produced by fibroblasts, suggesting a regulatory mechanism for the production of extracellular matrix at the dermal-epidermal junction. These findings demonstrate that matrilin-2 is expressed in normal skin by keratinocytes and fibroblasts and may thus contribute to cutaneous homeostasis.

Adult↗
PubMed2002

Treatment of recalcitrant cicatricial pemphigoid with the tumor necrosis factor alpha antagonist etanercept.

The treatment of cicatricial pemphigoid is generally regarded as difficult and usually relies on individual clinical experience. Corticosteroids, as drugs of first choice, often have to be combined with steroid-sparing agents to prevent hazardous, long-term side effects. We describe a 72-year-old woman with long-standing cicatricial pemphigoid recalcitrant to established treatment regimens who responded rapidly and lastingly to therapy with the tumor necrosis factor alpha antagonist etanercept. To our knowledge, this is the first report of its use in the treatment of a bullous autoimmune disease.

Aged↗
PubMed2002

A patient with hyper-IgE syndrome: a multisystem disorder.

A patient with hyper-IgE syndrome came to our attention with an exacerbation of atopic dermatitis. The medical evaluation showed typical features of hyper-IgE syndrome and a low number of cytotoxic T cells in the peripheral blood. This case serves as a reminder that hyper-IgE syndrome is a multisystem disorder.

Adult↗
PubMed2002

Role of postoperative radiotherapy in the management of Merkel cell carcinoma.

Merkel cell carcinoma (MCC) is a rare, aggressive neuroendocrine tumor of the skin with a high potential of locoregional relapse after surgery alone. This report is an update of our experience in the treatment of MCC. From January 1990 to May 2000, 31 patients with MCC, 13 men and 18 women aged between 34 and 92 years, were treated at the University of Cologne, Germany. Primary tumor sites were in the head and neck region in 13 patients, limbs in 13, and trunk in 5. The tumors were stage I in 26 of 31 patients, stage II in 4 of 31 and stage III in 1 of 31. Treatment included surgery alone in 14 of 31 patients, adjuvant postoperative radiotherapy in 16 of 31 patients, 1 of them had incomplete surgery, and definitive radiotherapy in 1 of 31 patients (stage III). Median overall survival (OS) after first diagnosis was 32 months (95% confidence interval: 0-75 months) with a 3-year OS rate of 47% (95% CI: 25-69%). Six of 31 patients relapsed locally after a median of 4 months, 10 of 31 patients developed regional node metastases, and 7 of 31 patients distant metastases. Nine patients died as a direct result of MCC. Locoregional control and disease-free survival were significantly improved in the group with postoperative radiotherapy (p = 0.023). Uni- and multivariate analysis revealed that head and neck location of the tumor and the lack of postoperative radiotherapy are unfavorable prognostic factors. Postoperative radiotherapy to the primary tumor region and the regional lymphatics is effective in the prevention of locoregional recurrence. Prospective clinical trials should be performed to confirm these observations.

Adult↗
PubMed2002

Acral erythrodysesthesia syndrome caused by intravenous infusion of docetaxel in breast cancer.

Docetaxel-induced skin reactions include hypersensitivity, edema, skin toxicity with erythrodysesthesia syndrome, infusion site reactions, alopecia, nail onycholysis, nail pigmentation, photosensitivity, scleroderma, and others, for example, stomatitis and paresthesias. However, of all reported effects, the acral erythrodysesthesia syndrome has only rarely been described in the literature. We report on two female patients with breast cancer who on treatment with docetaxel developed acral erythrodysesthesia syndrome. It presented as bizarrely shaped, burning skin reactions at their hands and feet. Histology of skin biopsies revealed microscopic damages to the eccrine sweat glands in both patients. Skin patch testing with docetaxel was negative. None of the reports dealing with side effects of docetaxel chemotherapy has described acral erythrodysesthesia syndrome with the histologic features of syringo-squamous metaplasia and eccrine neutrophilic hidradenitis. We propose here that these characteristic histologic features are essential in the differentiation from fixed drug eruption and localized graft-versus-host disease.

Antineoplastic Agents↗
PubMed2002

Treatment of chronic wounds: state of the art and future concepts.

The morbidity and mortality from chronic wounds of varying etiology present a significant health care problem. Multiple local disturbances and systemic disease can impair wound healing. Recently, experiments with tissue cultures and animal models have revolutionized the understanding of wound healing and the pathophysiological processes involved. In cooperation with clinicians and industrial partners novel therapeutic concepts including the topical application of growth factors and cell therapies have been developed. Cytokines that have been tested in clinical studies include epidermal growth factor, platelet-derived growth factor and fibroblast growth factor. These studies showed that an important aspect of the growth factor wound healing paradigm is the effective delivery of these polypeptides to the wound site. Current drug delivery strategies suffer from the inherent loss of drug activity due to the combined effects of physical inhibition and biological degradation. A molecular genetic approach in which genetically modified cells synthesize and deliver the desired growth factor in a time-regulated manner is a powerful means to overcome the limitations associated with the topical application of recombinant growth factor proteins.

Animals↗
PubMedDate not supplied

Efficacy and safety of the freeze-dried cultured human keratinocyte lysate, LyphoDerm 0.9%, in the treatment of hard-to-heal venous leg ulcers.

LyphoDerm (XCELLentis, Belgium) is an end-sterilized, freeze-dried lysate from cultured allogeneic epidermal keratinocytes, formulated into a hydrophilic gel. Its efficacy and safety were evaluated, in combination with standard care (hydrocolloid dressing and compression therapy), in 194 patients suffering from hard-to-heal (lasting more than 6 weeks and not responding to conventional therapy) venous leg ulcers. Two control groups received standard care, with or without vehicle, respectively. Patients had a median age of 67.5 years and the majority were females (61%). The median duration of the ulcer was 43 weeks and in 39% of the subjects it had been present for more than 1 year. Thirty-eight percent of the patients in the standard care + LyphoDerm group had complete ulcer healing within 24 weeks (primary end point) compared to 27% of patients in the standard care + vehicle pooled groups (P = 0.114) in the "as treated" intent-to-treat cohort (37% vs. 27% in the "as randomized intent-to-treat cohort; p = 0.137). In the subgroup of patients with enlarging ulcers, the difference between the two groups was significant (30% vs. 11%; p = 0.024 in the "as treated" intent-to-treat cohort and 31% vs. 9%; p = 0.005 in the "as randomized" intent-to-treat cohort). LyphoDerm was well tolerated and safe, and no differences in the frequency of adverse events were noted between the treatment groups. Although the primary objective of the study was not achieved, the exploratory analysis carried out in patients with enlarging ulcers suggests that LyphoDerm could offer a new prospect for the treatment of patients with venous ulcers that may prove to be a significant adjunct to the overall provision of care.

Adult↗