Eckart Köttgen

The relevance of murine animal models to study the development of allergic bronchial asthma

Bronchial asthma (BA) develops on the basis of a genetic predisposition and involves a characteristic sequence of changes in immune functions. In the immunopathogenesis, several phases can be distinguished: the initial stage is defined as the development of allergic sensitization. This step is dependent on: (i) T cell activation; (ii) IL‐4 production; (iii) IgE synthesis; and (iv) mediator release by effector cells. The second phase of allergic inflammation as a consequence of the T cell dependent sensitization is characterized by IL‐5 production and eosinophil activation and recruitment. Airway mucosa remodelling is the consequence of chronic inflammatory processes and represents the final stage of BA. In this article animal models will be discussed with regard to their relevance for these different phases in development of chronic allergic BA.

Inhibition of Cytokine Synthesis by Peritoneal Dialysate Persists throughout the CAPD Cycle

The current study focused on the effect of continuous ambulatory peritoneal dialysis (CAPD) dialysate obtained following different intraperitoneal dwell periods on the release of interleukin-6 (IL-6) and tumor necrosis factor-alpha (TNF alpha) from mononuclear leukocytes (PBMC). Aliquots of 5 x 10(6)/ml healthy peripheral PBMC were exposed to fresh or spent CAPD dialysate (10-240 min of intra-peritoneal dwell) and stimulated with Escherichia coli endotoxin (10 micrograms/ml, 2h). IL-6 and TNF alpha in cell supernatants were determined by specific enzyme immunoassays. Control PBMC in physiological buffer released 361 +/- 70 pg/ml IL-6 and 717 +/- 147 pg/ml TNF alpha (mean +/- SEM, n = 8), whereas exposure to fresh dialysis fluids severely suppressed cytokine release from PBMC (less than 30 pg/ml IL-6 and less than 15 pg/ml TNF alpha). A significant inhibition of IL-6 and TNF alpha release was also observed in PBMC exposed to spent dialysate. The inhibitory capacity of the spent fluids was pronounced with increasing intra-peritoneal dwell time (10 min: 183 +/- 45 pg/ml IL-6 and 538 +/- 109 pg/ml TNF alpha; 240 min: 26 +/- 5 pg/ml IL-6 and 105 +/- 30 pg/ml TNF alpha; mean +/- SEM, n = 16). These data indicate that the impairment of cell responsiveness following exposure of PBMC to peritoneal dialysate is not restricted to the unused fluids, but is also observed following intra-peritoneal equilibration. Moreover, our findings suggest the presence of cytokine inhibitory factors in the peritoneal dialysate of CAPD patients which appear to accumulate in the peritoneal effluent during the CAPD cycle.

Stimulation of plasminogen activation by recombinant cellular prion protein is conserved in the NH2-terminal fragment PrP23-110

The cellular prion protein (PrP(c)), tissue-type plasminogen activator (t-PA) and plasminogen are expressed in synaptic membranes in vivo. In the central nervous system the fibrinolytic system is associated with excitotoxin-mediated neurotoxicity and Alzheimers disease. Recently binding of the disease associated isoform of the prion protein (PrP(Sc)) to plasminogen and stimulation of t-PA activity have been reported. In this study the interaction of PrP(c) and plasminogen was investigated using chromogenic assays in vitro. We found that plasmin is able to cleave recombinant PrP(c) at lysine residue 110 generating an NH(2)-terminal truncated molecule that has previously been described as a major product of PrP(c) metabolism. We further characterized the proteolytic fragments with respect to their ability to stimulate plasminogen activation in vitro. Our results show that the NH(2)-terminal part of PrP(c) spanning amino acids 23-110 (PrP23-110) together with low molecular weight heparin stimulates t-PA mediated plasminogen activation in vitro. The apparent rate constant was increased 57 fold in the presence of 800 nM PrP23-110. Furthermore, we compared the stimulation of t-PA activity by PrP(c) and beta-amyloid peptide (1-42). While the activity of the beta-amyloid was independent of low molecular weight heparin, PrP23-110 was approximately 4- and 37 fold more active than beta-amyloid in the absence or presence of low molecular weight heparin. In summary, plasmin cleaves PrP(c) in vitro and the liberated NH(2)-terminal fragment accelerates plasminogen activation. Cleavage of PrP c has previously been reported. Thus cleavage of PrP(c) enhancing plasminogen activation at the cell surface could constitute a regulatory mechanism of pericellular proteolysis.

In an epidemiological sample the apolipoprotein E4 allele is associated to dementia and loss of memory function only in the very old

The apolipoprotein E4 allele has been reported to be associated with late onset Alzheimers disease. Here we report the relation of several neuropsychological test parameters and the diagnosis of dementia to the apolipoprotein E polymorphism in an epidemiological sample of 477 subjects aged 70-103 years. The apolipoprotein E4 allele was found to be associated with reduced performance in several sensitive neuropsychological memory tests and with diagnosis of dementia only in the oldest subjects (> 84 years). The association with dementia in this population based sample was much weaker than previously described and became only significant in a logistic regression analysis when age was included in the model.

Prion protein stimulates tissue-type plasminogen activator-mediated plasmin generation via a lysine-binding site on kringle 2.

Summary.u2002 Recombinant human prion‐protein (PrP23‐231) stimulates plasminogen activation by tissue‐type plasminogen activator (t‐PA). The stimulatory activity is conserved in the N‐terminal fragment (PrP23‐110). It has further been shown by others that PrPc binds to kringle‐domains of plasminogen. We compared the stimulatory activity of recombinant PrP23‐231 and PrP23‐110 on plasminogen activation catalyzed by t‐PA, urokinase (u‐PA), streptokinase and Desmodus salivary plasminogen activator (DSPAα1). As these plasminogen activators are distinct, with respect to their kringle domains we studied their binding to immobilized PrP23‐110. Plasminogen activation was measured in a chromogenic assay in vitro and binding studies were carried out using surface plasmon resonance technology. We found that recombinant full‐length prion protein, PrP23‐231, and PrP23‐110 specifically stimulate t‐PA mediated plasminogen activation. Two hundred nanomoles per liter of PrP23‐110 stimulated 1.8u2003nmolu2003L−1 t‐PA 48‐fold, 180u2003nmolu2003L−1 DSPAα1 2.5‐fold, 1.8u2003nmolu2003L−1 u‐PA 1.1‐fold, and 1.8u2003nmolu2003L−1 streptokinase 1.8‐fold. Our data show no specific binding for streptokinase. In contrast all plasminogen activators carrying a kringle domain bound to PrP23‐110. We further studied the effect of lysine on binding to PrP23‐110 and on plasminogen activation by DSPAα1 or t‐PA. Lysine decreased both the binding of t‐PA to PrP23‐110 and the stimulation of plasmin generation by t‐PA. Both binding and plasminogen activation of DSPAα1 were not influenced by the presence of lysine. All plasminogen activators tested bearing kringle domains bind to PrP23‐110. Binding to PrP23‐110 is not sufficient for stimulation of plasmin generation. Thus the lysine‐binding site of kringle 2 that is unique to t‐PA appears to mediate the specific stimulation of plasminogen activation by the cellular prion protein.

Verrucosis of hands and feet in a patient with combined immune deficiency

In immunocompromised patients, warts occur frequently and can be extensive. We describe a 24-year-old patient with severe therapy-resistant warts. In addition to human papillomavirus infection, he had chronic sinusitis, candidiasis, and atopic dermatitis. Anergy to delayed-type hypersensitivity skin test reaction, significant CD4 lymphopenia, and diminished in vitro T-cell proliferative response and interferon-gamma production indicated a deficiency of cellular immunity. Extremely low concentrations of serum IgM and IgG2 and a severe deficiency of in vitro IgM production pointed also to a humoral immunodeficiency syndrome. This case represents a combination of cellular and humoral immunodeficiencies that has not been previously described in association with warts.