Ruth Schiffer

Tissue dependence and differential cordycepin sensitivity of race-specific resistance responses in the barley-powdery mildew interaction

Epidermal cell monolayers prepared from partially dissected barley (Hordeum vulgare) coleoptiles were used for in vivo analysis of race-specific resistance to powdery mildew (Erysiphe graminis f. sp. hordei) specified by host genes Mla-1, Mla-12, and Mlg. Complete resistance governed by each of these genes is closely associated with hypersensitive cell death (hypersensitive response, HR) in primary leaf tissue. In contrast, Mla-12 coleoptile tissue reveals a fully compatible, Mla-1 coleoptile tissue a partially compatible, and Mlg coleoptile tissue an incompatible interaction upon challenge with pathogen races carrying corresponding avirulence functions. Quantitative recording of single plant-fungus interaction sites showed arrest of fungal development in papillae on Mlg coleoptiles. On Mla-1 and Mla-12 coleoptiles, attacked cells become predominantly penetrated by the fungus. Approximately one third of penetrated cells on Mla-1 coleoptiles subsequently undergo an HR. These sites reveal no further fungal ...

Resistance in barley against the powdery mildew fungus (Erysiphe graminis f.sp.hordei) is not associated with enhanced levels of endogenous jasmonates

Onset of acquired resistance of barley (Hordeum vulgare) chemically induced by 2,6-dichloroisonicotinic acid (DCINA) correlated with the accumulation of mRNA homologous to cDNA pHvJ256 which codes for a soluble leaf-thionin with a Mr. of 6 kDa [Wasternacket al., 1994a]. In the present work, we extend this finding by showing that the thionin transcript also accumulated following treatment of barley with the resistance-inducing compounds 3,5-dichlorosalicylic acid (DCSA), salicylic acid (SA), and an extract fromBacillus subtilis. The polypeptide showed antifungal activity against the biotrophic cereal pathogensErysiphe graminis f.sp.hordei andPuccinia graminis f.sp.tritici which may indicate a possible role in the mechanism of acquired resistance in barley. A thionin transcript hybridizing to pHvJ256 accumulated also in response to application of jasmonates, or treatments that elevated endogenous amounts of the plant growth substance, pointing to the possibility that signaling mediating defense responses in barley involves jasmonates. However, a topical spray application of jasmonic acid (JA) or jasmonate methyl ester (JM) did not protect barley leaves against infection byE. graminis. Performing a kinetic analysis by an enzyme immunoassay specific for (−)-JA, (−)-JM, and its amino acid conjugates, accumulation of jasmonates was detected in osmotically stressed barley but not at the onset of chemically induced or genetically based resistance governed by the powdery mildew resistance genesMlg, Mla12, ormlo5. Furthermore, the jasmonate-inducible proteins JIP-23 and JIP-60 were strongly induced following JM- but not DCINA-treatment or inoculation withE. graminis. Hence, in barley, no indications were found in favour for the previously proposed model of a lipid-based signaling pathway via jasmonates mediating expression of resistance in plants against pathogens.

Modulation of angiogenic functions in human macrophages by biomaterials

We examined the ability of polyvinylchloride (PVC), polytetrafluorethylene (PTFE) and tissue culture polystyrene (TCPS) to affect angiogenic functions in human monocyte-derived macrophages by measuring the mRNA expression of genes encoding angiogenic and anti-angiogenic molecules including basic fibroblast growth factor (bFGF), vascular endothelial growth factor (VEGF), angiopoietin-1 (Ang-1) and thrombospondin-1 (Tsp-1). The angiogenic activity of the corresponding macrophage conditioned media (CM) was measured by the proliferation of endothelial cells and the sprouting of new capillaries from fragments of human placental blood vessels. We determined that bFGF was not expressed in macrophages while VEGF and Tsp-1 mRNAs were expressed constitutively. Ang-1 was expressed in macrophages cultured up to 7 days on PTFE and TCPS independent of the culture stage. In contrast, macrophages cultured on PVC did not produce detectable amounts of Ang-1 mRNA after 7 days. CM from macrophages cultured either on PTFE or TCPS stimulated angiogenesis whereas CM from macrophages cultured on PVC inhibited it. The results demonstrate that polymers can cause differential expression of the angiogenic molecule Ang-1 in macrophages. They also induce different phenotypes of macrophages, which can either stimulate or inhibit angiogenesis suggesting a material-dependent influence on neovascularization.

Differential regulation of the expression of transporters associated with antigen processing, TAP1 and TAP2, by cytokines and lipopolysaccharide in primary human macrophages

Abstract:Objective: Using microarray technique we analysed global changes in gene expression of interferon-γ treated primary macrophages. Among the differential expressed genes identified we focussed on the expression of the transporters associated with antigen processing, TAP1 and TAP2, which are involved in the antigen presentation via MHC class I. Patients suffering from TAP deficiency syndrome have clinical manifestations including recurrent bacterial infections of the respiratory tract and chronic necrotizing granulomatous skin lesions. This is one reason why the regulation of TAP gene expression in antigen presenting cells such as macrophages might provide important general insights into the generation of cellular immune response to multiple pathogens. Additionally IFN-α is important in adjuvant tumortherapie although the working mechanisms are unknown. Because of the possibility of the TAPs to be involved in these mechanisms we studied the expression of these transporters in human macrophages after stimulation with pro-inflammatory mediators. Material and treatment: Monocyte derived macrophages were treated for 24 h with either interferon-γ, interferon-α, interleukin-1β (each 100 U/ml) or lipopolysaccharide (1 μg/ml). Methods: IFN-γ induced gene expression was analysed using microarray technique. TAP expression was investigated by RT-PCR, northern blot- and western blot analysis. Results: TAP1 and TAP2 were constitutively expressed at a low level. IFN-γ upregulated the expression of both transporters. LPS caused an increase similar to the effect of IFN-γ. Treatment with IFN-α stimulated also the expression, however, less than IFN-γ. In contrast, IL-1β stimulation had no effect. Conclusion: Our data show that the transporters associated with antigen presentation are differentially regulated by pro-inflammatory mediators in human macrophages. The finding that IFN-α stimulates the expression of proteins involved in cytotoxic effector functions of macrophages contributes to the understanding of the immunoregulatory role of type 1 interferons and may help to explain the efficacy of IFN-α in the treatment of tumors.

The Contact of Human Macrophages with Extracellular Matrix Proteins Selectively Induces Expression of Proinflammatory Cytokines

The interaction of macrophages with proteins of the extracellular matrix (ECM) is important for the regulation of the immune and nonimmune functions displayed by these cells. Little, however, is known about the ability of different ECM proteins to transmit inflammatory signals into macrophages. Here we investigated the effect of the ECM proteins collagen type I, fibrin and fibronectin on the expression of the proinflammatory cytokines interleukin-1β (IL-1β) and IL-8 using RT-PCR, Northern and Western blot analysis and ELISA technique. It was found that collagen strongly induced IL-1β and IL-8 expression in the macrophages. Fibronectin also stimulated cytokine expression, however, the amounts of the specific mRNAs were significantly lower compared to those induced by collagen. On the protein level IL-1β revealed a close correlation to the mRNA expression. In contrast, fibrin did not elicit any IL-1β and IL-8 response. These data show that different ECM proteins vary in their ability to induce proinflammatory cytokine expression in human macrophages suggesting that the protein composition of the ECM might be crucial in the initiation of inflammatory processes.

Detection of a TH1-like cytokine expression pattern in lesional skin of a patient with cutaneous tuberculosis.

Cutaneous tuberculosis constitutes only a small proportion of cases of tuberculosis and has become an uncommon disease in recent years. Lupus vulgaris is a form of cutaneous tuberculosis, clinically characterized by scaly plaques with apple-jelly-colored nodules. The disease is caused by a reinfection of the skin with Mycobacterium tuberculosis, which is exogenously or endogenously disseminated by the hematological or lymphatic routes (Werschler et al. 1990). Histopathological findings have demonstrated the predominance of T cells in the granulomas. Human T cells with in vitro reactivity to mycobacterial antigens have been shown to secrete high amounts of IFN-γ after in vitro stimulation with M. tuberculosis (Del Prete et al. 1991; Gong et al. 1998). In the study reported here we analyzed the cytokine expression in lesional skin of a patient with lupus vulgaris. Skin biopsies were obtained from a 43-year-old male patient who presented with a single, large skin lesion on his right elbow which had become apparent 13 years previously (Fig.1). There was no other evidence of previous tuberculous foci in other locations, and no detectable signs of either previous or simultaneous systemic diseases. The epidermis of the skin biopsy specimen was atrophic and focally hyperplastic. A marked inflammatory granulomatous reaction was seen in the reticular dermis with central caseation necrosis and Langhans giant cells (tuberculoid

A Common Basis of Genetically Based and Induced Resistance in Cereals

We have analysed the phenomenon of systemically activated resistance (SAR) in the interaction of the powdery mildew fungus (Erysiphe graminis) with the respective hosts, wheat (Triticum aestivum L.) and barley (Hordeum vulgare L.). One aspect of the work concerns the identification and assessment of molecular markers for SAR, i.e. gene products that accumulate with a certain kinetics after the onset of SAR. Such markers might be a valuable tool for the identification of new resistance inducing compounds.