Ingrid Lorenz

Expression of the antioxidant stress protein heme oxygenase-1 (HO-1) in human leukocytes: Acute and adaptational responses to endurance exercise

Inducible heme oxygenase (HO-1) is an antioxidant stress protein, that is mainly induced by reactive oxygen species (ROS), cytokines and hyperthermia. By using flow cytometry the present investigation demonstrated a rise in the cytoplasmic expression of HO-1 in lympho- (L), mono- (M) and granulocytes (G) of 9 endurance-trained male subjects after a half marathon run. The expression was more pronounced in M (median: 98.3% HO-1 positive cells/4.31 mfc) and G (94.8%/1.93 mfc) than in L (80.1%/1.51 mfc) when measured 3 h post-exercise. Additionally the exercise protocol caused a rise in the plasma levels of myeloperoxidase, TNF alpha and interleukin-8 (IL-8), indicating an inflammatory response. We could detect a correlation between IL-8 and HO-1, directly after exercise, that was apparent in G (r = 0.67, p < .05) and L (r = 0.80, p < .05), but did not reach significance in M (r = 0.65, p = 0.06). An additional detection of HO-1 at rest in 12 untrained subjects showed a higher baseline expression of HO-1 compared to the athletes. The regulatory pathways leading to an increased expression of HO-1 after endurance exercise are not completely clear, but a causal involvement of a cytokine-mediated generation of ROS must be discussed. We supposed that the down-regulation of the baseline expression of HO-1 in athletes reflects an adaptional mechanism to regular exercise training.

Subtyping of natural killer cell cytotoxicity deficiencies in haemophagocytic lymphohistocytosis provides therapeutic guidance

The familial form of haemophagocytic lymphohistiocytosis (HLH) is a fatal disease, with allogeneic stem cell transplantation (SCT) being the only curative treatment. In contrast, patients with secondary (infection‐associated) HLH usually do not require SCT. Since it often is difficult to distinguish primary and secondary HLH, we wanted to identify a tool that provides guidance on whether SCT is required. The clinical outcome of 65 HLH patients was analysed in relation to the recently reported four types of defects in natural killer (NK)‐cell cytotoxicity in HLH. None (0%) of the 36 patients with NK‐cell deficiency type 3 attained a sustained (1‐year) remission after stopping therapy without receiving SCT, in contrast to 45% (13/29) non‐type 3 patients (P < 0·001). Most type 3 patients (22/36) underwent SCT (14/22, 64% are alive), whereas 11 of 14 that did not receive SCT died, and the three others had received HLH‐therapy during the last year of follow‐up. Of 54 patients analysed for perforin expression and/or mutation, the five with perforin deficiency were all type 3 patients. The data suggests that HLH patients with NK‐cell deficiency type 3 will probably require SCT to survive. Thus, NK‐cell deficiency classification may provide valuable guidance in judging whether an HLH‐patient needs SCT.

Deficient activation of CD95 (APO-1/ Fas)-mediated apoptosis: a potential factor of multidrug resistance in human renal cell carcinoma

The pronounced resistance of human renal cell carcinoma (RCC) to anticancer-induced apoptosis has primarily been related to the expression of P-glycoprotein and effective drug detoxification mechanisms. Because the CD95 system has recently been identified as a key mediator of anticancer drug-induced apoptosis, we analysed the contribution of the CD95 system to chemotherapy-induced apoptosis in four newly established RCC cell lines. Here, we demonstrate that all RCC cell lines expressed CD95-receptor and -ligand. Exposure to agonistic anti-CD95 antibodies resulted in induction of apoptosis and significant (P< 0.05) reduction of cell number in three out of four cell lines, indicating that the essential components for CD95-mediated apoptosis were present and functionally intact in the majority of these RCC cell lines. Moreover, treatment of cultures with bleomycin or topotecan, a novel topoisomerase I inhibitor with little substrate affinity for P-glycoprotein, led to induction of apoptosis and significant (P< 0.05) dose-dependent reduction of cell number in all RCC cell lines. Both anticancer drugs also induced upregulation of CD95 ligand expression in all cell lines. Additionally, augmentation of CD95 receptor expression was found in three RCC cell lines, including one p53-mutated cell line, whereas another p53-mutated cell line showed no or only a weak CD95 receptor upregulation after exposure to topotecan or bleomycin, respectively. Despite this upregulation of CD95 receptor and ligand, antagonistic antibodies directed against CD95 receptors or ligands could not inhibit induction of apoptosis by topotecan and bleomycin in any cell line. Thus, although a functionally intact CD95 signalling cascade is present in most RCC cell lines, the anticancer drugs topotecan and bleomycin that induce upregulation of CD95 receptor and ligand fail to effectively activate CD95-mediated apoptosis. This deficient activation of CD95-mediated apoptosis might be an important additional factor for the multidrug resistance phenotype of human RCCs.

Inhibition of Hematopoiesis by in Vivo Activated T Cells Secreting High Amounts of Interferon-γ (IFN-γ) Plus Interleukin 10 (IL-10)

T cell clones were isolated from patients showing suppressed hematopoiesis without any signs of acute or chronic viral infections. All clones were CD4-positive and were derived from the peripheral blood by limiting dilution in the presence of low concentrations of IL-2. Characteristically, the majority of these clones secreted 50 – 300 IU/ml of IFN-γ# and 100 to 2500 pg/ml of IL-10 per 5×l05 clone cells on day 3–5 following subculture. Culture supernatants displayed a weak suppressive activity on erythropoiesis using standard colony forming assays and ficoll-separated bone marrow cells. However, the addition of 1/10 of 20 Gy-irradiated clone T cells secreting both cytokines impaired hematopoiesis in vitro. Here, myeloid cell colony formation appeared to be more affected than erythroid burst formation.