Abstract Cytokine deprivation from activated T cells leads to apoptosis associated with down‐regulation of the bcl‐2 gene product. It is not clear, however, how cytokines other than interleukin‐2 (IL‐2) may affect this process and regulate the involvement of other apoptosis‐modulating genes. We show that a group of cytokines including IL‐2, IL‐4, IL‐7 and IL‐15, which can all signal through the γ chain of the IL‐2R (IL‐2Rγ), prevent the apoptosis of IL‐2‐deprived activated T cells. This rescue involves the induction of the anti‐apoptosis genes ( bcl‐2 and bcl ‐ x L ), but causes little change in expression of bax and bcl ‐ x S , which promote apoptosis. Furthermore, the prevention of apoptosis and induction of proliferation by the common γ chain cytokines can be dissociated. Thus, when proliferation is blocked, the common γ chain cytokines still induce up‐regulation of bcl‐2 relative to bax and retard apoptosis. These cytokines can thus regulate the persistence or removal of effector T cells by coordinating the balance between genes which promote and those which inhibit apoptosis, events which are probably mediated at least in part by signals through the common γ chain. These data also implicate inappropriate T cell apoptosis resulting from a dysfunctional common γ‐chain as part of the pathophysiological defect in patients with X‐linked severe‐combined immunodeficiency (SCID).
Tumor necrosis factor alpha (TNF-alpha) is a cytokine of cytotoxic and proinflammatory properties. It is believed to play an important role in inflammatory and demyelinization processes in the central nervous system (CNS). The aim of this study was to investigate what pathological changes could be produced by a stereotaxic administration of TNF-alpha in vivo into rat brain. Specimens were evaluated after staining with hematoxylin and eosin (H & E), Kluver-Barrera staining and using immunocytochemical methods. Disturbances of the blood-brain barrier (BBB) were analyzed as well as inflammatory infiltrates, changes in neurons, astrocytes and myelin. TNF-alpha injected in vivo into a rat brain caused a prominent inflammatory reaction in the cerebral meninges and a local cytotoxic brain edema when compared with the control group. Moreover, disturbances of the BBB premeability, infiltration of blood-borne macrophages in the area of the cytokine injection and early arising astrogliosis were observed. These results suggest that TNF-alpha can be an important mediator of inflammatory processes in the CNS.
Widespread use of MCF-7 human breast carcinoma cells as a model system for breast cancer has led to variations in these cells between different laboratories. Although several reports have addressed these differences in terms of proliferation and estrogenic response, variations in sensitivity to apoptosis have not yet been described. Tumor necrosis factor alpha (TNF-alpha) has been shown to both induce apoptosis and inhibit proliferation in MCF-7 cells. We observed that TNF-alpha inhibited proliferation in MCF-7 cell variants from three different laboratories (designated M, L, and N). MCF-7 M cells were resistant to TNF-alpha-induced apoptosis, whereas MCF-7 L cells were moderately resistant to the effect of TNF-alpha. A third variant, MCF-7 N, underwent apoptosis when exposed to TNF-alpha. Analysis of the p55 TNF-alpha receptor (TNFR) 1 expression revealed the greatest expression in MCF-7 N cells, whereas the MCF-7 L and M cells expressed 89 and 67% of MCF-7 N cell TNFR1 levels, respectively. Ceramide generation occurred in all three variants in response to TNF-alpha treatment, with MCF-7 N cells expressing the greatest increase. Cleavage of the CPP32/caspase 3 substrate poly(ADP-ribose) was observed in MCF-7 N and L cells as early as 3 and 6 h, respectively, but poly(ADP-ribose) cleavage was not observed in MCF-7 M cells. The delayed protease activation in the L variant may represent the mechanism by which these cells display delayed sensitivity to TNF-a-induced apoptosis. Expression of the Bcl-2, Mcl-1, Bcl-X, Bax, and Bak proteins was analyzed to determine whether the differences in MCF-7 cell sensitivity to apoptosis could be correlated to the differential expression of these proteins. Whereas Bak, Bcl-X, and Mcl-1 levels were identical between variants, the levels of Bcl-2 were 3.5-3.8-fold higher and the levels of Bax were 1.5-1.7-fold lower in the resistant variants (M and L) as compared with those of the sensitive variant (N). Taken together, these results suggest that differences in susceptibility to TNF-alpha-induced apoptosis among MCF-7 breast cancer cell variants may be explained by differences in TNFR expression, ceramide generation, differential expression of the Bcl-2 family of proteins, and protease activation.
Glandular epithelial cells of the human endometrium initiate apoptosis in the secretory phase of the cycle. To better understand the regulation of apoptosis in this paradigm of endocrine-regulated cell turnover, we studied the expression of the cell death regulatory genes, bax, bcl-2, and bcl-x, in human proliferative and secretory endometria relative to the absence or presence of apoptosis. As assessed by immunohistochemistry, levels of BAX protein were modest in proliferative endometrium and increased dramatically in the secretory phase when apoptosis was most prevalent. Expression of BAX was predominantly localized to epithelial cells of the functionalis layer of the secretory endometrium. In contrast, BCL-2 immunoreactivity was maximal during the proliferative phase and decreased in the secretory phase. Moreover, BCL-2 was topographically concentrated in the basalis layer. Immunoreactive BCL-X protein was observed mostly in glandular epithelial cells of the human endometrium. Compared with proliferative endometrium, secretory endometrium showed stronger BCL-X staining, especially in the functionalis layer. By Western blotting we confirmed that both proliferative and secretory endometrium expressed the long or antiapoptosis form as well as the short or proapoptosis form of the BCL-X protein. Taken together, our results demonstrate a coordinated pattern of expression of bcl-2 gene family members in human endometrium during the menstrual cycle, with a shift toward greater levels of the proapoptosis protein, BAX, occurring in glandular epithelial cells during the secretory phase of the cycle. Therefore, we conclude that cyclic changes in endometrial growth and regression may be precisely regulated by shifts in the ratio or balance of BCL-2 and related proteins in glandular epithelial cells.
Summary The author examines the question of when and under what circumstances the Conciliar Declaration actually became tangible in Poland. The Declaration was intended to lead to a redefining of relations between Judaism and the Roman Catholic Church. Krajewski sifts through the conflict-ridden developments affecting the Catholic Church in the era of Communist rule in Poland, and in the subsequent period of transformation. Concrete steps in and implementation of Jewish-Christian dialogue can really only be established from the 1990s, in a time when the pontificate of John Paul II played a contributory role. This article also looks into current societal trends, which are once again straining relations between the churches and Judaism, and posing new challenges on the implementation of dialogue between the parties.
