Effect of liver regeneration after partial hepatectomy and ischemia-reperfusion on expression of growth factor receptors.

AIM: To investigate the effects of experimental partial hepatectomy and normothermic ischemia-reperfusion damage on the time course of the expression of four different growth factor receptors in liver regeneration. This is relevant due to the potential therapeutic use of growth factors in stimulating liver regeneration. METHODS: For partial hepatectomy (PH) 80% of the liver mass was resected in Sprague Dawley rats. Ischemia and reperfusion (I/R) were induced by occlusion of the portal vein and the hepatic artery for 15 min. The epidermal growth factor receptor, hepatic growth factor receptor, fibroblast growth factor receptor and tumour necrosis factor receptor-1 were analysed by immunohistochemistry up to 72 h after injury. Quantitative RT-PCR was performed at the time point of minimal receptor expression (24 h). RESULTS: In immunohistochemistry, EGFR, HGFR, FGFR and TNFR1 showed biphasic kinetics after partial hepatectomy with a peak up to 12 h, a nadir after 24 h and another weak increase up to 72 h. During liver regeneration, after ischemia and reperfusion, the receptor expression was lower; the nadir at 24 h after reperfusion was the same. To evaluate whether this nadir was caused by a lack of mRNA transcription, or due to a posttranslational regulation, RT-PCR was performed at 24 h and compared to resting liver. In every probe there was specific mRNA for the receptors. EGFR, FGFR and TNFR1 mRNA expression was equal or lower than in resting liver, HGFR expression after I/R was stronger than in the control. CONCLUSION: At least partially due to a post-transcriptional process, there is a nadir in the expression of the analysed receptors 24 h after liver injury. Therefore, a therapeutic use of growth factors to stimulate liver regeneration 24 h after the damage might be not successful.

Asymptomatic HIV infection is characterized by rapid turnover of HIV RNA in plasma and lymph nodes but not of latently infected lymph-node CD4+ T cells.

OBJECTIVES: To study the kinetics of plasma viraemia and HIV-infected lymph-node cells in stable asymptomatic HIV infection with high CD4+ T-cell counts. METHODS: Nine asymptomatic HIV-infected patients with stable CD4+ T-cell counts (510-1350 x 10(6)/l) were treated with a triple-drug combination. Plasma viraemia was determined at days 0, 3, 7, 10, 14, 21 and 28 of treatment [Roche polymerase chain reaction (PCR) and ultrasensitive PCR assay]. Sequential lymph-node biopsies were examined in four patients before and after 4 weeks of treatment. Productively infected cells were counted in lymph-node sections (in situ hybridization). The infection rates of FACS-sorted CD4+ lymph-node T cells and the expression of single-spliced, double-spliced and full-length HIV transcripts were determined. RESULTS: HIV plasma RNA half-lives ranged from 1.4 to 2.7 days. Viral turnover varied between 0.07 and 7.54 x 10(8) copies per day. The number of productively infected lymph-node cells as well as the amount of extracellular virus in germinal centres was markedly reduced during treatment, paralleled by a clearance of single-spliced, double-spliced and full-length HIV transcripts from CD4+ lymph-node T cells. Plasma viraemia remained detectable with an ultrasensitive PCR assay in three out of four patients. The percentage of lymph-node CD4+ T cells harbouring proviral DNA decreased only slightly. CONCLUSIONS: The kinetics of HIV replication are rapid in stable asymptomatic infection, and the magnitude of replication varies considerably. Productively infected lymph-node cells and extracellular virus in germinal centres undergo a rapid turnover, whereas latently infected CD4+ T cells have a lower rate of turnover. The latter may contribute substantially to viral persistence during therapy.

[Effects of IL-2 and IL-6 on the immunoglobulin synthesis of lymphocytes from CVID patients]. / Effekte von IL-2 und IL-6 auf die Immunglobulin-synthese von Lymphozyten von CVID-Patienten.

Peripheral blood lymphocytes from five hypogammaglobulinemic patients suffering from common variable immunodeficiency (CVID) were stimulated with Staphylococcus aureus Cowan I (SAC) and pokeweed mitogen (PWM). The assays were substituted with interleukin-2 (IL-2) and interleukin-6 (IL-6) in different combinations. In three patients who were deficient for IgM in vivo a combination of SAC and IL-2 induced a normal IgM synthesis in vitro. In these patients a deficient IL-2 synthesis is probably the cause of CVID. In only one patient a "class switch" from IgM to IgG was detectable. Stimulation with PWM which is T-cell-dependent induced in one out of the five patients a normal IgM synthesis. Another CVID patient showed no defect in IgM or IgG synthesis in vitro. With these in vitro assays it seems possible to identify CVID patients who might profit from a therapy with human IL-2 in vivo.

The superoxide generating system of B cell lines. Structural homology with the phagocytic oxidase and triggering via surface Ig.

EBV-transformed B lymphocyte cell lines (EBV-BLCL) produce superoxide after stimulation with phorbol ester, a capacity unique among nonmyeloid cells. The superoxide producing system of EBV-BLCL (B cell oxidase) was compared with the phagocytic NADPH-oxidase and the relationship of the capacity to produce superoxide to the presence of the EBV-genome was analyzed. The two EBV-transformed B cell lines F1 and HELL generated superoxide in response to PMA (2.3 nmol/10(6) F1 cells x 1 h and 6.27 nmol/10(6) HELL cells x 1 h with 1 microgram/ml of PMA), whereas no superoxide release was detected with the EBV-positive Burkitt lymphoma line WIL-2 and the EBV-negative plasmocytoma line U-266. Also, F1 and HELL showed lucigenin-dependent chemiluminescence (CL) after PMA-treatment, whereas no CL responses were detected from WIL-2 or U-266. Further, F1 and HELL cells contained a low potential cytochrome b-245 (10.9 and 61.0 pmol/mg protein, respectively) and also a 45 kDa diphenylene-iodonium (DPI)-binding peptide, both components of the phagocytic NADPH-oxidase. In contrast, neither the cytochrome b-245 nor the 45 kDa DPI-binding peptide were detected in WIL-2 and U-266. In addition, DPI inhibited O2- production by PMA-stimulated EBV-BLCL and polymorphonuclear granulocytes. Further, F1 line cells showed superoxide dismutase-inhibitable lucigenin-dependent CL when triggered by protein A-bearing staphylococci (Cowan strain I) or by a mAb directed against human IgG in the presence of solid-phase goat anti-mouse-Ig antibody. From a panel of eight EBV-BLCL, only five responded with CL when exposed to protein A-bearing staphylococci, whereas all showed CL when treated with phorbol ester. Inasmuch as all eight EBV-BLCL possessed surface Ig and a "functional" oxidase, their differential response to cross-linking of surface Ig may be determined by differences in signal transduction. Superoxide production by EBV-BLCL appears thus related to expression of an electron transport chain structurally homologous, if not identical, with the "phagocytic" NADPH-oxidase. Apparently, the presence of EBV-genome in B cell lines does not per se lead to expression of this oxidase. This suggests that nontransformed B cells may, at a certain differentiation stage, also express a superoxide-generating chain. From the finding of stimulation of superoxide production of EBV-BLCL via surface Ig it appears possible that also Ag may be able to trigger such B cells to production of superoxide which might have an important role in the physiology of B cells.