Grb3-3 is up-regulated in HIV-1-infected T-cells and can potentiate cell activation through NFATc

The MAPK pathway is required for T-cell activation; however, its role in modulating T-cell function following human immunodeficiency virus type 1 (HIV-1) infection is poorly understood. In this report, we investigated whether Grb3-3, an isoform of the Grb2 (growth factor receptor-bound protein-2) adaptor molecule that is associated with the MAPK pathway, could be involved. We found that Grb3-3, but not its isoform Grb2, is markedly up-regulated in CD4(+) peripheral blood mononuclear cells derived from either in vitro HIV-1-infected cultures or HIV-1-infected human subjects. Analysis of HIV-1 gene products indicated that Tat and Nef, both of which have been implicated in modulating T-cell function, can independently induce expression of Grb3-3. By using NFAT/AP-1, AP-1, or NFAT reporter assays, we found that Grb3-3 can potentiate NFAT (but not AP-1) promoter activity in Jurkat T-cells upon engagement of the T-cell receptor and CD28 co-receptor. In addition, potentiation of NFAT by Grb3-3 is substantially suppressed by MEKK1, a kinase that may play an important role in retaining NFAT in the cytoplasm, and by cyclosporin A. Finally, we also found that Grb3-3 potentiates HIV-1 long terminal (LTR) repeat promoter activity following T-cell receptor stimulation, an effect that can be largely suppressed by cyclosporin A. Taken together, this study indicates that Grb3-3 is a cellular factor that can be up-regulated by HIV-1. In addition, Grb3-3 can also function as a positive factor for T-cell activation and, in doing so, may aid in establishing an intracellular environment that can optimally support HIV-1 replication.

In vitro effects of mycophenolic acid on cell cycle and activation of human lymphocytes

The immunosuppressant mycophenolic acid (MPA) selectively inhibits proliferation of T- and B-lymphocytes by blocking inosine 5'-monophosphate-dehydrogenase (IMPDH), the key enzyme for de-novo-synthesis of guanine nucleotides. In an in vitro study the effects of MPA on human peripheral blood lymphocyte activation markers and on cell cycle characteristics were investigated. Mononuclear cells from healthy volunteers were incubated with phytohaemagglutinin (PHA) and increasing doses of MPA. After 72 h incubation an aliquot of the cells was stained with propidium iodide and measured by FACS analyses to assess the DNA shape. In addition, the expression of the activation markers HLA-DR and CD25 on T- and B-lymphocytes was determined by flow cytometry analysis.PHA stimulation led to a significant increase of the S-phase of cell cycle. PHA stimulation clearly increased mean fluorescence intensity (MFI) of HLA-DR expression on B-lymphocytes. PHA stimulation also elevated the number of CD25 positive B-lymphocytes. Expression of HLA-DR on T-lymphocytes was not influenced by PHA, whereas CD25 expression and MFI significantly increased. All the observed PHA induced effects were reduced by co-incubation with increasing doses of MPA. The data presented show that in vitro the immunosuppressive effect of MPA can be demonstrated using FACS technology on a cellular level. MPA leads to an inhibition of cell cycle proliferation in peripheral blood lymphocytes.

Cutting edge: SLP-76 cooperativity with FYB/FYN-T in the Up-regulation of TCR-driven IL-2 transcription requires SLP-76 binding to FYB at Tyr595 and Tyr651

SLP-76 (Src homology (SH) 2-domain-containing leukocyte protein of 76 kDa) and FYB/SLAP (FYN-T-binding protein/SLP-76-associated protein) are two hemopoietic cell-specific adaptor proteins downstream of TCR-activated protein tyrosine kinases. SLP-76 has been implicated as an essential component in T cell signaling. FYB is selectively phosphorylated by FYN-T, providing a template for the recruitment of FYN-T and SLP-76 SH2 domains. Coexpression of FYN-T, FYB, and SLP-76 can synergistically up-regulate IL-2 production in T cells upon TCR ligation. In this report, we show that two tyrosines, Tyr595 and Tyr651, of FYB are major sites of phosphorylation by FYN-T and mediate binding to SLP-76 in Jurkat T cells. Furthermore, the synergistic up-regulation of IL-2 promoter activity in the FYN-T-FYB-SLP-76 pathway is contingent upon the interaction between FYB and SLP-76, but not the interaction between FYB and FYN-T. These observations define a pathway by which SLP-76 interacts with downstream components in the up-regulation of T cell cytokine production.

Novel isoform of lymphoid adaptor FYN-T-binding protein (FYB-130) interacts with SLP-76 and up-regulates interleukin 2 production

T-cell activation involves the participation of protein-tyrosine kinases p56(lck) and ZAP-70/SYK as well as lymphoid proteins such as SLP-76 and FYB/SLAP. FYB/SLAP has the hallmarks of an adaptor protein that binds to the SH2 domains of the Src kinase FYN-T and SLP-76. Whereas two forms of FYB at 120 and 130 kDa have been identified biochemically, a cDNA encoding only the lower molecular weight isoform has been cloned (termed FYB-120 or SLAP-130). In this study, we report the isolation of an alternative isoform of FYB with a molecular mass of 130 kDa (FYB-130) that has the same structure as FYB-120 except for an insertion of 46 amino acids toward the carboxyl-terminal region of the protein. FYB-120 and FYB-130 share an ability to bind to the SH2 domains of FYN-T and SLP-76, to act as substrates for p59(FYN-T), and to be expressed in the cytoplasm and nucleus of T-cells. Differences were noted between the isoforms in the efficiency of binding to SLP-76 and in the preferential expression of FYB-130 in mature T-cells. When co-expressed together with FYN-T and SLP-76, FYB-130 caused a significant increase in anti-CD3-driven NF-AT transcription. Finally, fluorescence in situ hybridization analysis localized the FYB gene to human chromosome 5 at position p13.1. FYB-130 therefore represents a novel variant of FYB protein that can up-regulate T-cell receptor-driven interleukin 2 production in mature T-cells.

Signaling scaffolds in immune cells

Of the past several years progress in understanding TCR signal transduction has led to the discovery of new kinases, adapter molecules and multiple signaling pathways. The study of molecules such as LAT, SLP-76, FYB, SKAP-55 and VAV have revealed multiple mechanisms with which to control the activation of downstream signaling pathways through RAS, PLC gamma-1 and ERK/MAPK. Signaling through SLP-76 can play a role in TCR-induced cytoskeleton changes through activation of effector molecules in the RAC/RHO-family of GTPases. In addition, SLP-76 through its association with FYB/FYN-T appears to play a role in IL-2 gene transcription following TCR activation. Finally, these newly identified adaptor molecules, such as LAT, may be crucial in T-cell activation by enhancing the recruitment of critical kinases to glycolipid-enriched microdomains of the activated T-cell receptor complex.

SHPS-1 is a scaffold for assembling distinct adhesion-regulated multi-protein complexes in macrophages

Inhibitory immunoreceptors downregulate signaling by recruiting Src homology 2 (SH2) domain-containing tyrosine and/or lipid phosphatases to activating receptor complexes [1]. There are indications that some inhibitory receptors might also perform other functions [2] [3]. In adherent macrophages, two inhibitory receptors, SHPS-1 and PIR-B, are the major proteins binding to the tyrosine phosphatase SHP-1. SHPS-1 also associates with two tyrosine-phosphorylated proteins (pp55 and pp130) and a protein tyrosine kinase [4]. Here, we have identified pp55 and pp130 as the adaptor molecules SKAP55hom/R (Src-kinase-associated protein of 55 kDa homologue) and FYB/SLAP-130 (Fyn-binding protein/SLP-76-associated protein of 130 kDa), respectively, and the tyrosine kinase activity as PYK2. Two distinct SHPS-1 complexes were formed, one containing SKAP55hom/R and FYB/SLAP-130, and the other containing PYK2. Recruitment of FYB/SLAP-130 to SHPS-1 required SKAP55hom/R, whereas PYK2 associated with SHPS-1 independently. Formation of both complexes was independent of SHP-1 and tyrosine phosphorylation of SHPS-1. Finally, tyrosine phosphorylation of members of the SHPS-1 complexes was regulated by integrin-mediated adhesion. Thus, SHPS-1 provides a scaffold for the assembly of multi-protein complexes that might both transmit adhesion-regulated signals and help terminate such signals through SHP-1-directed dephosphorylation. Other inhibitory immunoreceptors might have similar scaffold-like functions.

FYN-T-FYB-SLP-76 interactions define a T-cell receptor zeta/CD3-mediated tyrosine phosphorylation pathway that up-regulates interleukin 2 transcription in T-cells

Protein-tyrosine kinases p56(Lck), SYK, and ZAP-70 and downstream adaptors LAT and SLP-76 have been implicated as essential components in T-cell activation. Another lymphoid-specific adaptor FYB/SLAP has also been identified as a predominant binding partner of SLP-76 and the Src kinase FYN-T, although its role in the activation process has been unclear. In this study, we demonstrate that FYN-T selectively phosphorylates FYB providing a template for the recruitment of FYN-T and SLP-76 SH2 domain binding. This interaction is unusual in its distinct cytoplasmic localization and its long term stable kinetics of phosphorylation. Furthermore, we demonstrate for the first time that the co-expression of all three components of the FYN-T-FYB-SLP-76 matrix can synergistically up-regulate T-cell receptor-driven interleukin 2 transcription activity. These findings document the existence of a T-cell receptor-regulated FYN-T-FYB pathway that interfaces with the adaptor SLP-76 and up-regulates lymphokine production in T-cells.

Comparison of the immunoglobulin-G-specific seroreactivity of different recombinant antigens of the human herpesvirus 8

The open reading frames ORF 52, ORF 65, K12, and K8.1 of the human herpesvirus 8 (HHV8) were expressed as glutathione-S-transferase (GST) fusion proteins and analysed by Western blotting (WB) and enzyme-linked immunosorbent assay (ELISA). The open reading frame (ORF) 65 and K8.1 antigens gave the highest reactivity (71%) in sera from HIV-dependent Kaposi's sarcoma (KS) patients. Therefore both antigens appear to be essential for HHV8 diagnostics, whereas ORF K12 and ORF 52 were of minor importance. Using polymerase chain reaction (PCR) out of the peripheral blood of these KS patients, 48% were detected as positive. By testing an N-terminal-deleted construct (amino acid 80-171) of ORF 65, we could show that the N-terminal region of this protein is essential to mediate full immunogenic reactivity. By analysing different deletion mutants of ORF K8.1, the major epitope was found to be located between aa 29 and 101. The prevalence of antibodies directed against the different antigens was determined for healthy blood donors to be 3-6%. The different antibody patterns obtained in HIV-patients with and without KS support the hypothesis that different antibody profiles develop during the course of KS.

FYB (FYN binding protein) serves as a binding partner for lymphoid protein and FYN kinase substrate SKAP55 and a SKAP55-related protein in T cells

TcRzeta/CD3 ligation initiates a signaling cascade involving CD4/CD8-p56(lck), p59(fyn), and ZAP-70, as well as lymphoid downstream proteins VAV, SLP-76, and FYB/SLAP. A current question concerns the nature of the downstream binding partner(s) of FYB in T cells. In this study, using a two-hybrid screen with FYB as bait, we have identified eight clones, four of which correspond to the recently published lymphoid protein SKAP55, and two which correspond to a related protein with some 44% homology to SKAP55 (termed SKAP55-related protein, SKAP55R). The SKAP55 clones showed only minor differences (two substitutions and one residue deletion) from SKAP55. SKAP55R has the same overall structure as SKAP55 except for the presence of a unique N terminus with a well-defined coiled-coil domain. Both SKAP55 and SKAP55R were found to bind FYB through their SH3 domains and to act as substrates for the FYN kinase in T cells. Furthermore, immunofluorescence confocal microscopy showed that FYB and SKAP55 colocalize in the perinuclear region of cells. SKAP55 also colocalizes with another FYB binding protein, SLP-76. Taken together, these observations demonstrate that FYB is part of an interactive matrix with SKAP55 and a SKAP55-related protein.

[Direct-current treatment of chemically induced mammary carcinoma in an animal model: MR volumetric assessment of the effect of the therapy]

PURPOSE

To investigate the effect of direct current treatment (DCT) on the growth of mammary carcinomas in rats by MR-volumetry.

METHODS

Chemically induced mammary adenocarcinomas in a control group (n = 17) were compared with treated tumours (18 C/cm3 in group A: n = 7 or 36 C/cm3 in group B: n = 12). 31 untreated tumours were situated near a treated tumour (group C). Experiments were carried out using one positive electrode in the tumour centre and three negative electrodes in the periphery. The tumour volume was measured by MRI before, and 1, 3, 6, 9 and 12 weeks after treatment.

RESULTS

12 weeks after DCT, the mean tumour volume in group A (164% +/- 158%, p < 0.05) and group B (13% +/- 24%, p < 0.001) was significantly reduced compared to the control group (434% +/- 230, Mann-Whitney U-Test). Complete tumour regression occurred in 42% of tumours in group B and was not achieved in group A, C and control group. Tumour growth in group C was decreased compared to the control group.

CONCLUSIONS

The effectiveness of DCT was found to depend on the applied dosage -36 C/cm3 was more effective than 18 C/cm3. The effect of DCT is not limited to the area between the electrodes.

Safety and cost effectiveness of a 10 x 10(9)/L trigger for prophylactic platelet transfusions compared with the traditional 20 x 10(9)/L trigger: a prospective comparative trial in 105 patients with acute myeloid leukemia

In 105 consecutive patients with de novo acute myeloid leukemia (French-American-British M3 excluded), we compared prospectively the risk of bleeding complications, the number of platelet and red blood cell transfusions administered, and the costs of transfusions using two different prophylactic platelet transfusion protocols. Two hundred sixteen cycles of induction or consolidation chemotherapy and 3,843 days of thrombocytopenia less than 25 x 10(9)/L were evaluated. At the start of the study, each of the 17 participating centers decided whether they would use a 10 x 10(9)/L prophylactic platelet transfusion trigger (group A/8 centers) or a 20 x 10(9)/L trigger (group B/9 centers). Bleeding complications (World Health Organization grade 2-4) during treatment cycles were comparable in the two groups: 20 of 110 (18%) in group A and 18 of 106 (17%) in group B (P = .8). Serious bleeding events (grade 3-4) were generally not related to the patient's platelet count but were the consequence of local lesions and plasma coagulation factor deficiencies due to sepsis. Eighty-six percent of the serious bleeding episodes occurred during induction chemotherapy. No patient died of a bleeding complication. There were no significant differences in the number of red blood cell transfusions administered between the two groups, but there were significant differences in the number of platelet transfusions administered per treatment cycle: pooled random donor platelet concentrates averaged 15.4 versus 25.4 (P < .01) and apheresis platelets averaged 3.0 versus 4.8 (P < .05) for group A versus group B, respectively. This resulted in the cost of platelet therapy being one third lower in group A compared with group B without any associated increase in bleeding risk.

Treatment and prognosis of gastric lymphoma

To assess the developments in the prognosis and treatment of patients with primary gastric non-Hodgkin's lymphoma we reviewed 178 papers in English, German, and French on the subject that were listed on MEDLINE between January 1974 and April 1995. We analysed the results of 3157 patients, and during that period the overall survival increased from 37% to 87%. Overall survival by Ann Arbor stage was 57%. 998/1296 (77%) for stage IE, 231/330 (70%) for stage II1E, 107/290 (37%) for stage II2E, 53/172 (31%) for stage IIIE, and 122/451 (27%) for stage IV. Over half the publications recommended resection alone. Only 12 (15%) thought that radiotherapy or chemotherapy, alone or in combination, was adequate. The results of all treatments were similar in 1296 patients with stage IE disease. For stage IIE-IVE disease, however, 66 (82%) of authors suggested a treatment protocol that included resection, and of these 39 (49%) recommended a combination of resection, local radiotherapy, and systemic chemotherapy. The number of patients reported was too small for us to be able to give precise recommendations for treatment of gastric non-Hodgkin's lymphoma, and we have been able to give only an evaluation of current treatments.

[Problems in diagnosis and therapy of malignant pleural mesothelioma]

The incidence of malignant pleural mesothelioma increased continuously during recent years. This is related to widespread use and processing of asbestos in the last decades. Characteristical symptoms like dyspnea, cough and thoracic pain are common in almost all pulmonal diseases. Therefore the possible occurrence of a pleural tumor is often neglected. This leads to a delay between onset of symptoms and the establishment of diagnosis. With X-ray and computed tomography 80% of the pleural tumors can be proved. Only in few cases the histopathological analysis of the pleural fluid leads to diagnosis. However, thoracoscopy or thoracotomy remain the most reliable means of obtaining a definitive tissue diagnosis. At the time of operation advanced stages are found in many cases, therefore palliative surgery is indicated. Due to high morbidity and mortality pleuropneumonectomy should be done only in selected patients. Pleurectomy or pleurodesis is often sufficient to release patients' symptoms. Chemotherapy and radiation have not proven effective in controlling malignant mesothelioma. In conclusion pleural mesothelioma remains a tumor with a very poor prognosis. Long term survival is occasional even in case of multimodal treatment.

Regulation of Vav-SLP-76 binding by ZAP-70 and its relevance to TCR zeta/CD3 induction of interleukin-2

T cell activation stimulates p56(lck), p59(fyn), ZAP-70, Vav-SLP-76 binding, and IL-2 transcription. Major questions concern the tyrosine-kinase and relevant site(s) needed for Vav-SLP-76 complex formation and its role in IL-2 production. Here, we show that of the three kinases, only ZAP-70 phosphorylates SLP-76 at specific sites that allow Vav SH2 domain binding. Therefore, while p56(lck) regulates proximal events, ZAP-70 acts downstream on targets such as SLP-76. We also show by in vitro and in vivo analysis that two SLP-76 pYESP motifs (Y113 and Y128) mediate binding, the first being more efficient. A third pYEPP motif (Y145) failed to bind. Finally, TCR zeta CD3 ligation of T cell hybridoma DC27.10 induces IL-2 production without detectable Vav-SLP-76 binding. Therefore, despite effects of Vav-SLP-76 on IL-2 expression, Vav-SLP-76 binding per se is not essential for IL-2 production in all T cells.

[Long-term results of abdominal surgery interventions. Different evaluation from the viewpoint of the patient, the surgeon and the public health office]

The patient, the surgeon and the public health officer (Versorgungsamt) assess the long-term results of abdominal operations differently. We tried to objectivize these different assessments. The clinical data were collected retrospectively. Data on postoperative subjective state and degree of handicap were obtained in a written patient survey (March 1995). Two groups with benign diseases and one group with malignant disease were examined: 59 patients who had undergone sigmoidectomy for diverticulitis (30 female and 29 male patients, median age: 61.5 years), 347 patients subjected to proximal gastric vagotomy for duodenal ulcers (72 female and 275 male patients, median age: 46 years) and 158 patients who had undergone gastrectomy for gastric carcinoma (56 patients female, 102 patients male, median age: 61 years). The public health officer, classed 35.6% of the patients who had undergone sigmoidectomy and 34.6% of the patients who underwent vagotomy as officially handicapped with a stated grade of disablement, 77.2% of the patients with gastrectomy were officially classed as handicapped. When other diseases were taken into account in addition, 27.1% of the patients who had undergone sigmoidectomy, 27.4% of those who had undergone vagotomy and 75.9% of the patients with gastrectomy had received passes officially identifying them as severely handicapped persons. In the vast majority of cases, the combination of several different ailments had resulted in recognition of a graded handicap and severely disabled person's pass, skeletal, cardiac and circulatory ailments being the most frequent. In spite of this, the evaluation of post-operative course by our patients, the surgeon and the public health officer (as reflected in the official state classification) in terms of the degree of handicap clearly differed.

Dupuytren's contracture in the black population: a case report and review of the literature

A case report of a 34-year-old black man with Dupuytren's contracture of his left small finger and review of the literature of Dupuytren's disease in the black population is presented. A high incidence of trauma (54%) was associated with these cases.

Delineation of segmental liver anatomy. Comparison of ultrasonography, spiral CT and MR imaging for preoperative localization of focal liver lesions to specific hepatic segments

PURPOSE

The purpose of this study was to determine the ability of noninvasive imaging methods to localize focal liver lesions to specific hepatic segments.

MATERIAL AND METHODS

In a prospective study we evaluated 24 patients with hepatic masses with ultrasonography (US), spiral CT and MR imaging.

RESULTS

The primary segmental location of the lesions was correct with US in 15 of 24 patients (63%), with CT in 21 of 24 patients (88%) and with MR imaging in 17 of 22 patients (77%). The full extent of the lesions was correctly described with US in 9 of 24 patients (38%), with CT in 16 of 24 patients (67%) and with MR in 12 of 22 patients (55%).

CONCLUSION

Among the noninvasive imaging methods, CT provides the best information for determining the segmental location and planning the surgical approach to hepatic resections.

Heterotopic pancreas. A difficult diagnosis

Heterotopic pancreas is seen in one of every 500 laparotomies or 0.55-13% of autopsies. Despite modern diagnostic procedures (endoscopy, endoscopic ultrasound) it is difficult to diagnose preoperatively. A 51-year-old patient with a 30-year history of recurrent gastric ulcers was diagnosed with a gastric wall tumor. Endoscopic biopsy sample showed normal gastric mucosa. Endoscopic ultrasound and contrast radiography were not able to specify the gastric wall tumor. The local excision and histologic preparation of the tumor showed heterotopic pancreatic tissue within the gastric submucosa without any signs of malignancy. Three years postoperatively the patient is without any complaints. There have been no further signs of gastric ulcers.

Hematopoietic cell phosphatase (HCP) regulates p56LCK phosphorylation and ZAP-70 binding to T cell receptor zeta chain

Ligation of the T cell receptor complex and CD4 leads to activation of the protein tyrosine kinases p56lck and p59fyn resulting in phosphorylation of TcR zeta chain and the recruitment of ZAP-70. In this study, we have reconstituted p56lck phosphorylation of TcR zeta and ZAP-70 recruitment in heterologous cells and examined the role of the tyrosine phosphatase HCP in regulating the process. Both p56lck and p59fyn induce significant phosphorylation of TcR zeta. However, under conditions of comparable p56lck and p59fyn expression, p56lck was found to induce three to four fold greater in vivo phosphorylation of TcR zeta. HCP dephosphorylated p56lck, ZAP-70 and the TcR zeta chain. Further, dephosphorylation of the different TcR zeta isoforms results in disruption of the interaction between TcR zeta and ZAP-70. These results indicate that HCP acts to negatively regulate signal transduction pathways in T cells.