Renal hypertrophy in hyperglycemic non-obese diabetic mice is associated with persistent renal accumulation of insulin-like growth factor I

The non-obese diabetic mouse is a model of spontaneous insulin-dependent diabetes as a result of autoimmune destruction of pancreatic beta cells, similar to the disease seen in human Type I diabetes. This mouse strain develops glomerular lesions reminiscent of those seen in human disease. The study presented here investigated the changes in renal insulin-like growth factor (IGF) system in hyperglycemic non-obese diabetic mice. Female non-obese diabetic mice and their age- and sex-matched controls were euthanized 4 days, 2 wk, and 4 wk after the onset of glycosuria. Kidney weight increased in diabetic mice, beginning at 2 wk after the onset of glycosuria. This renal hypertrophy was associated with an increase in renal extractable IGF-I protein. However, a decrease in IGF-I mRNA was observed at the same time. Serum IGF-I levels remained stable after 2 wk of diabetes and decreased at 1 month. No change was detected in renal IGF-I receptor mRNA levels. Renal cortical IGF binding protein (IGFBP)-1 mRNA levels were increased. Ligand blot analysis revealed a significant increase in serum and renal 30-kd IGFBP and a decrease in serum and kidney IGFBP-3 and IGFBP-4 at 30 days of diabetes. Insulin therapy prevented the increases in kidney weight, renal IGF-I, and 30-kd IGFBP, but did not reverse the decreased serum IGF-I levels observed at 1 month of diabetes. In summary, renal hypertrophy in non-obese diabetic mice is associated with a persistent accumulation of renal IGF-I and, IGFBP-1. These changes were partially reversed with insulin therapy, which did not correct the hyperglycemia, suggesting an important role for insulin deficiency in mediating these changes in the IGF system. These findings suggest that the IGF system may play a potential role in the development of diabetic nephropathy.

Modulation of insulin-like growth factor I (IGF-I) receptors and membrane-associated IGF-binding proteins in endometrial cancer cells by estradiol

Insulin-like growth factor I (IGF-I) receptors and membrane-associated IGF-binding proteins (IGFBPs) were examined in Ishikawa endometrial cancer cells. Our findings suggest that about 95% of [125I]IGF-I is bound to membrane-associated IGFBPs rather than to IGF-I receptors. Specifically, [125I]IGF-I binding to cell membranes could be completely displaced by cold IGF-I or IGF-II, but not by insulin, suggesting that binding was primarily due to IGFBPs. This was confirmed by using [125I]des-(1-3)IGF-I as the ligand. Des-(1-3) IGF-I binds with high affinity to IGF-I receptors, but with markedly lower affinity to IGFBPs. [125I]Des-(1-3)IGF-I bound to Ishikawa cells was displaced by IGF-I, IGF-II, and insulin. These results suggest that measuring IGF-I receptor levels using labeled IGF-I may be misleading. Accordingly, we evaluated the differential binding of [125I]IGF-I and [125I]des-(1-3)IGF-I to study the involvement of the IGF system in the stimulation of Ishikawa cell growth by estradiol. IGF-I stimulates Ishikawa cell proliferation, but at low concentrations, and this stimulation is largely dependent on the presence of estradiol. Estradiol caused a 2.5-fold increase in IGF-I receptor levels. Moreover, estradiol reduced soluble IGFBP levels, presumably increasing the availability of IGFs for their receptors. This elevation in IGF-I receptor levels and the decrease in IGFBP levels were accompanied by a 3.5-fold increase in IGF-I receptor messenger RNA and a 2.5-fold decrease in IGFBP messenger RNAs. These experiments suggest that estradiol sensitizes endometrial cancer cells to the effects of IGFs by simultaneously elevating receptor levels and decreasing (potentially inhibitory) IGFBP levels.

CT appearance of a traumatic cataract

We describe a case of a traumatic cataract that presented on CT as a hypodense lens with a hyderdense rim. The finding reflects the pathogenesis of this entity: a capsular tear and consequent entry of fluid into the lens.

Tyrosine phosphorylation of measles virus nucleocapsid protein in persistently infected neuroblastoma cells

Subacute sclerosing panencephalitis is a slowly progressing fatal human disease of the central nervous system which is a delayed sequel of measles virus (MV) infection. A typical pathological feature of this disease is the presence of viral ribonucleocapsid structures in the form of inclusion bodies and the absence of infectious virus or budding viral particles. The mechanisms governing the establishment and maintenance of a persistent MV infection in brain cells are still largely unknown. To understand the mechanisms underlying MV persistence in neuronal cells, a tissue culture model was studied. Clone NS20Y/MS of the murine neuroblastoma C1300 persistently infected with the wild-type Edmonston strain of MV secretes relatively high levels of alpha/beta interferon (IFN). As shown previously, treatment of the persistently infected cultures with anti-IFN serum converted the persistent state into a productive infection indicated by the appearance of multinucleated giant cells. In this study, we have investigated whether alpha/beta IFN produced by NS20Y/MS cells activates cellular protein tyrosine kinases which will induce tyrosine phosphorylating activity specific to virus-infected cells. We present data to show augmented protein tyrosine kinase activity in the persistently infected cells. We demonstrate that the MV N protein is phosphorylated on tyrosine in addition to serine and threonine in the persistent state but not in NS20Y cells acutely infected with MV.

Reversal of the measles virus-mediated increase of phosphorylating activity in persistently infected mouse neuroblastoma cells by anti-measles virus antibodies

To investigate the effect of persistent measles virus infection on signal transduction in cells of neuronal origin, the mouse neuroblastoma cell line NS20Y/MS, which is persistently infected with measles virus, was used. The results demonstrate an approximate 50% increase in total phosphorylation and a similar increase in protein kinase C (PKC) activity. Western blot analysis with anti-total PKC or anti-PKC-alpha antibodies revealed a significant increase in the level of an 80K immunoreactive PKC in NS20Y/MS cells. Following incubation of NS20Y/MS cells with polyclonal anti-measles virus antibodies, which down-regulate the level of measles virus proteins, total and PKC-mediated phosphorylation returned to the basal level of uninfected cells. This effect was reversible and removal of the antibodies resulted in restoration of the high level of total and PKC-mediated phosphorylation. The release of infectious measles virus was strongly inhibited by incubation of NS20Y/MS cells with the PKC inhibitor, 1-(5-isoquinolinylsulphonyl)-2-methylpiperazine (H-7). These results demonstrate that measles virus induces elevation in cellular phosphorylation which is essential for measles virus production.

Thymic humoral factor, THF-gamma 2, enhances immunotherapy of murine cytomegalovirus (MCMV) infection by both CD4+ and CD8+ immune T cells

Infection of mice with murine cytomegalovirus (CMV) presents a model for the study of the role of the immune system in the pathogenesis of human CMV. The contribution of the different spleen cell subsets in conferring curative immunocytotherapy to fatally MCMV-infected immunosuppressed mice was assessed using adoptive immunotherapy. It was found that the efficacy of passively transferred immune spleen cells is dose dependent and that the therapeutic effect can be enhanced considerably by treating donor mice with thymic humoral factor (THF-gamma 2). Polymerase chain reaction (PCR) of the donor spleen population was negative, indicating that no MCMV-DNA was transferred with the immune cells. Analysis of the donor mice after THF-gamma 2 treatment showed increased levels of CMV-neutralizing antibodies, while enhancement of natural killer (NK) activity was transient and lasted only during the early phase of the infection. FACS analysis demonstrated that treatment with THF-gamma 2 restored the size of both cell subsets CD4+ and CD8+ that were decreased following MCMV infection. It is shown that both CD4+ and CD8+ T-cell subsets participate in controlling the development of the fatal disease in MCMV-infected immunosuppressed recipients. It is suggested that the enhancement of the immunocompetence of both populations of spleen cells from treated donors is mediated in part by the restoration of Interleukin-2 (IL-2) production by THF-gamma 2.

Antibody-dependent transcriptional regulation of measles virus in persistently infected neural cells

Application of neutralizing anti-hemagglutinin antibodies to mouse neuroblastoma cells (NS20Y/MS) persistently infected with measles virus (MV) leads to a significant reduction of viral structural proteins within 6 days. While the transcriptional gradient for MV-specific mRNAs remained unaffected upon antibody treatment, the total amount of MV-specific transcripts dropped by 80% after 24 h. The expression of genomic RNA was affected similarly, with slightly slower time kinetics. Both transcription and expression of the viral structural proteins could be completely reactivated when viral antibodies were removed from the tissue culture. The same findings could be obtained in rat glioma cells persistently infected with subacute sclerosing panencephalitis virus (C6/SSPE) but not in cells of nonneural origin. The data indicate that antibody-induced antigenic modulation affects the early stages of viral transcription within a few hours after the addition of antibodies and leads to an almost complete repression of viral gene expression in cells of neural origin.

Persistent measles virus infection enhances major histocompatibility complex class I expression and immunogenicity of murine neuroblastoma cells

The effect of persistent measles virus infection on the expression of major histocompatibility complex (MHC) class I antigens was studied. Mouse neuroblastoma cells C1300, clone NS20Y, were persistently infected with the Edmonston strain of measles virus. The persistently infected cell line, NS20Y/MS, expressed augmented levels of both H-2Kk and H-2Dd MHC class I glycoproteins. Activation of two interferon(IFN)-induced enzymes, known to be part of the IFN system: (2'-5')oligoadenylate synthetase and double-stranded-RNA-activated protein kinase, was detected. Measles-virus-infected cells elicited cytotoxic T lymphocytes that recognized and lysed virus-infected and uninfected neuroblastoma cells in an H-2-restricted fashion. Furthermore, immunization of mice with persistently infected cells conferred resistance to tumor growth after challenge with the highly malignant NS20Y cells. The rationale for using measles virus for immunotherapy is that most patients develop lifelong immunity after recovery or vaccination from this infection. Patients developing cancer are likely to have memory cells. A secondary response induced by measles-virus-infected cells may therefore induce an efficient immune response against non-infected tumour cells.

Natural killer (NK) cell response after vaccination of volunteers with killed influenza vaccine

Many experiments have shown convincingly that natural killer (NK) cell activity against viral infections is an important early defence mechanism in mice. Since the NK response occurs soon after infection, often long before clinical signs of disease become manifest, it has been difficult to design studies to monitor accurately NK cell kinetics following infection, without actually administering pathogens to volunteers. There is therefore little data pertaining to the role of NK cells in humans. Nevertheless, a number of studies have shown elevated NK activity in response to herpes simplex and influenza virus infections in humans. Our study was designed to show that NK activity could be provoked in humans by exposure to viral particles without actual live viral infection. The development of NK cell response in the peripheral blood of volunteers shortly after vaccination with killed influenza trivalent vaccine was studied. The results demonstrate that killed virus vaccine induces and augments NK cell activity for relatively long periods. Such data may prove valuable for designing possible modes of augmenting NK activity as a therapeutic tool.

Immune reactivity of the tumor-resistant X/Gf mouse

Parameters of immune reactivity of the tumor-resistant X/Gf mouse have been studied. X/Gf mice show better survival than do control strains following i.p. inoculation with graded doses of YAC lymphoma cells. The natural killer cell activity of X/Gf mice was higher than that of control mice, and this elevated NK activity was inherited by (C57BL/6 X X/Gf)F1 mice. Differences in NK activity of fresh spleen cells from X/Gf, C57BL/6, and (C57BL/6 X X/Gf)F1 mice were not reflected in their ability to lyse in vitro-derived, cloned, transformed cell lines from X/Gf or C57BL/6 mice in an 8 h 51Cr assay; however, the X/Gf-derived malignant cells were more sensitive to lysis than the C57BL/6-derived cells. In order to test whether X/Gf mice demonstrated any exceptional ability to recognize and destroy altered autologous cells, experiments were performed with TNP-modified syngeneic cells. While X/Gf and B10.A effector cells appeared to respond with similar magnitude, hapten-modified X/Gf cells were stronger stimulator cells and more sensitive targets than control strain cells. The ability of X/Gf mice to reject H-2 compatible and incompatible skin grafts is normal, as judged by a comparison of the rejection times with control strains. Allogeneic mixed lymphocyte reactivity, T-cell-mediated lympholysis, delayed-type hypersensitivity reactions, and in vivo phagocytosis of inert particles are of comparable magnitude in X/Gf and control strain mice.

T-cell cytotoxicity and aging: differing causes of reduced response in individual mice

Specific T-cell cytotoxic responses to allogeneic and hapten-modified syngeneic cells decrease with age. In order to determine the causes of these reduced T-cell cytotoxic responses, spleen cells from individual young and senescent C57BL/6J female mice were mixed in various proportions in culture with either X-irradiated BALB/c spleen cells or trinitrophenyl-modified syngeneic cells and the resultant cytotoxic responses determined in comparison to those of spleen cells from young and old mice stimulated alone. In both allogeneic and hapten-modified syngeneic cytotoxicity, it was found that a low percentage of the aged mice suffered from decreased helper-cell activity or from increase of suppressor activity, while the majority of mice showed no synergy, positive or negative, with the cells from the young donor. Studies of interleukin-2 (IL-2) activity were performed on conditioned medium from spleen cells from mice of various ages cultured for 24 h with concanavalin A. Those preparations from senescent mice that showed reduced IL-2 activity did not contain activity suppressive or competitive to IL-2 produced by spleen cells from young mice. Limiting dilution of spleen cells from mice of various ages in the presence of semi-allogeneic stimulatory cells and subsequent assay of the resultant allogeneic cytotoxicity provided a measure of the frequency of cytotoxic units. Parallel experiments in which crude IL-2 was added to the limit dilution cultures provided a measure of the frequency of cytotoxic cell precursors. Once again in these experiments, individual senescent mice demonstrated different defects. Three different types of age-related defects were observed. Certain aged mice were devoid of detectable cytotoxic units and cytotoxic T-lymphocyte precursor at the cell dilutions used. Other senescent mice demonstrated a very low frequency of cytotoxic units (approximately 1/40 000) as compared with young mice (approximately 1/5 000), and the addition of crude IL-2 to cultures from these mice did not improve reactivity. A third group of old mice, those with a moderate age-related decrease in the frequency of cytotoxic units (approximately 1/12 000), demonstrated a cytotoxic T-lymphocyte precursor frequency in the presence of crude IL-2 which was comparable to that of young mice (approximately 1/1000).

The affinity and spectrum of cross reactivity of antibody production in senescent mice: the IgM response

Experiments were performed to determine whether the IgM component of the primary humoral immune response of senescent mice differs from that of young-adult mice in its affinity, specificity or heterogeneity. For this purpose, mice were immunized with the T-dependent antigen, TNP-KLH, or the T-independent antigen, TNP-LPS. Affinity and specificity of the anti-TNP response were studied at the cellular level by the plaque inhibition technique using the cross-reacting haptens TNP-epsilon-aminocaproic acid )TNP-EACA),DNP-EACA and ONP-EACA. It was found that when the immunogen was TNP-KLH, the peak IgM response was delayed in senescent animals by several days as compared to the response in young adults. However, the number of PFC on the day of peak response was comparable. No age related delay in the peak of response was detected when the antigen was TNP-LPS although the magnitude of response was reduced in old age. The average affinity of the plaque forming cell responses to both immunogens is comparable in young and old mice.