Andrea Modesti

Lymphoproliferative disorder and imbalanced T-helper response in C/EBP beta-deficient mice.

C/EBP beta is considered a key element of interleukin‐6 (IL‐6) signalling as well as an important transcriptional regulator of the IL‐6 gene itself. We describe here how mice lacking C/EBP beta develop a pathology similar to mice overexpressing IL‐6 and nearly identical to multicentric Castlemans disease in human patients, with marked splenomegaly, peripheral lymphadenopathy and enhanced haemopoiesis. Humoral, innate and cellular immunity are also profoundly distorted, as shown by the defective activation of splenic macrophages, the strong impairement of IL‐12 production, the increased susceptibility to Candida albicans infection and the altered T‐helper function. Our data show that C/EBP beta is crucial for the correct functional regulation and homeostatic control of haemopoietic and lymphoid compartments.

Coexpression of IL-6 and soluble IL-6R causes nodular regenerative hyperplasia and adenomas of the liver

Studies with tumor necrosis factor p55 receptor‐ and interleukin‐6 (IL‐6)‐deficient mice have shown that IL‐6 is required for hepatocyte proliferation and reconstitution of the liver mass after partial hepatectomy. The biological activities of IL‐6 are potentiated when this cytokine binds soluble forms of its specific receptor subunit (sIL‐6R) and the resulting complex interacts with the transmembrane signaling chain gp130. We show here that double transgenic mice expressing high levels of both human IL‐6 and sIL‐6R under the control of liver‐specific promoters spontaneously develop nodules of hepatocellular hyperplasia around periportal spaces and present signs of sustained hepatocyte proliferation. The resulting picture is identical to that of human nodular regenerative hyperplasia, a condition frequently associated with immunological and myeloproliferative disorders. In high expressors, hyperplastic lesions progress with time into discrete liver adenomas. These data strongly suggest that the IL‐6/sIL‐6R complex is both a primary stimulus to hepatocyte proliferation and a pathogenic factor of hepatocellular transformation.

Characterization and intracellular localization of the Epstein-Barr virus protein BFLF2: Interactions with BFRF1 and with the nuclear lamina

ABSTRACT We have reported in the accompanying paper that the BFRF1 protein of Epstein-Barr virus (EBV) is important for efficient primary viral envelopment and egress (A. Farina, R. Feederle, S. Raffa, R. Gonnella, R. Santarelli, L. Frati, A. Angeloni, M. R. Torrisi, A. Faggioni, and H.-J. Delecluse, J. Virol. 79:3703-3712). Here we describe the characterization of the product of the EBV BFLF2 gene, which belongs to a family of conserved herpesviral genes which include the UL31 genes of herpes simplex virus and of pseudorabies virus and whose products are known to interact with UL34, the positional homolog of BFRF1. BFLF2 is an early transcript and is expressed in a variety of cell lines upon EBV lytic cycle activation. Western blotting of purified virion preparations showed that BFLF2 is a component of intracellular virions but is absent from mature extracellular virions. Coimmunoprecipitation experiments indicated that BFLF2 interacts with BFRF1, which was confirmed by immunofluorescence confocal microscopy showing that the two proteins colocalize on the nuclear membrane not only upon cotransfection in epithelial cells but also during viral replication. In cells carrying an EBV mutant with the BFRF1 gene deleted (293-BFRF1-KO cells) BFLF2 expression was low, and it was restored to wild-type levels upon treatment of the cells with the proteasome inhibitor MG132. Furthermore, recomplementing the 293-BFRF1-KO cells by BFRF1 transfection restored BFLF2 expression to the wild-type level. In addition, when expressed alone BFLF2 was localized diffusely inside the nucleus, whereas in the presence of BFRF1 the two proteins colocalized at the nuclear rim. Finally, 293 epithelial cells transfected with either protein or cotransfected were analyzed by electron microscopy to investigate potential alterations in the morphology of the nuclear membrane. The ultrastructural analysis revealed that (i) BFRF1 caused duplications of the nuclear membrane, similar to those reported to occur during the course of herpesviral replication, and (ii) while BFLF2 alone did not cause any apparent alteration, coexpression of the two proteins dramatically induced profound convolutions of the duplicated nuclear membrane. Both biochemical and morphological analysis showed association of the BFRF1-BFLF2 complex with a component of the nuclear lamina, lamin B. Taken together, these results and those of the accompanying paper (Farina et al., J. Virol. 79:3703-3712) indicate an important role of BFRF1 and BFLF2 in the early steps of EBV maturation at the nuclear membrane.

In Vitro and in Vivo Antitumoral Effects of Combinations of Polyphenols, or Polyphenols and Anticancer Drugs: Perspectives on Cancer Treatment

Carcinogenesis is a multistep process triggered by genetic alterations that activate different signal transduction pathways and cause the progressive transformation of a normal cell into a cancer cell. Polyphenols, compounds ubiquitously expressed in plants, have anti-inflammatory, antimicrobial, antiviral, anticancer, and immunomodulatory properties, all of which are beneficial to human health. Due to their ability to modulate the activity of multiple targets involved in carcinogenesis through direct interaction or modulation of gene expression, polyphenols can be employed to inhibit the growth of cancer cells. However, the main problem related to the use of polyphenols as anticancer agents is their poor bioavailability, which might hinder the in vivo effects of the single compound. In fact, polyphenols have a poor absorption and biodistribution, but also a fast metabolism and excretion in the human body. The poor bioavailability of a polyphenol will affect the effective dose delivered to cancer cells. One way to counteract this drawback could be combination treatment with different polyphenols or with polyphenols and other anti-cancer drugs, which can lead to more effective antitumor effects than treatment using only one of the compounds. This report reviews current knowledge on the anticancer effects of combinations of polyphenols or polyphenols and anticancer drugs, with a focus on their ability to modulate multiple signaling transduction pathways involved in cancer.

Frequent overexpression of multiple ErbB receptors by head and neck squamous cell carcinoma contrasts with rare antibody immunity in patients

In an effort to elucidate the role of ErbB receptors in human head and neck squamous cell carcinoma (HNSCC), expression abnormalities and subcellular localization of epidermal growth factor receptor (EGFR), ErbB2, ErbB3, and ErbB4 were investigated along with EGF and tenascin by immunohistochemistry in 38 carcinomas as compared to adjacent normal mucosa of 24 cases. Although tumour‐specific overexpression affected each ErbB receptor (EGFR 47%, ErbB2 29%, ErbB3 21%, ErbB4 26%), EGFR abnormalities were most prevalent. The latter, and overexpression of more than two ErbB receptors in the same tumour, which always included EGFR, correlated with metastatic disease. ErbB products were specifically detected on the cell membrane and in the cytoplasm. In contrast, ErbB4 was uniquely localized to the nucleus in 7 carcinomas and a tumour‐derived cell line, indicating a role for regulated intramembrane proteolysis resulting in nuclear ErbB4 translocation in HNSCC. Expression of prototype ligand EGF or low‐affinity stromal activator tenascin correlated significantly with EGFR overexpression, implying chronic EGFR activation. Simultaneous overexpression of additional ErbB receptors in most of these cases suggested recurrent involvement of receptor heterodimers. In spite of frequent ErbB receptor alterations, autologous ErbB serum antibodies were rare, with only 1 of 38 tumour patients exhibiting an ErbB2‐specific immune response. Based on upregulation of several known immunosuppressive molecules, scarcity of ErbB‐specific antibodies is consistent with attenuation of natural tumour‐specific immune responses in HNSCC. Copyright

The effects of dietary flavonoids on the regulation of redox inflammatory networks.

Dietary flavonoids are a large family of polyphenols ubiquitously expressed in plants. Recent evidence show that flavonoids possess several anti-inflammatory activities due to their ability to scavenge reactive oxygen and nitrogen species (ROS and RNS), to inhibit the pro-inflammatory activity of ROS-generating enzymes including cyclooxygenase (COX), lipoxygenase (LOX) and inducible nitric oxide synthase (iNOS) and to modulate different intracellular signaling pathways from NF-kB to mitogen-activated protein kinases (MAPKs) through perturbation of redox-sensible networks in immune cells. This report will review current knowledge on the anti-inflammatory effects of flavonoids on immune cells focusing on their ability to modulate multiple redox-sensible pathways involved in inflammation.

Effects of vitamin C on health: a review of evidence.

Vitamin C is an essential dietary nutrient for the biosynthesis of collagen and a co-factor in the biosynthesis of catecholamines, L-carnitine, cholesterol, amino acids, and some peptide hormones. The lack of vitamin C causes scurvy, a pathological condition leading to blood vessel fragility and connective tissue damage due to failure in producing collagen, and, finally, to death as result of a general collapse. Vitamin C is potentially involved also in cancer and cardiovascular diseases prevention. In addition, vitamin C effects on nervous system and chronically ill patients have been also documented. This review attempts to summarize recent and well established advances in vitamin C research and its clinical implications. Since vitamin C has the potential to counteract inflammation and subsequent oxidative damage that play a major role in the initiation and progression of several chronic and acute diseases, it represents a practical tool to administer for the early prevention of these pathologic conditions.

Dietary Flavonoids: Molecular Mechanisms of Action as Anti- Inflammatory Agents

Flavonoids are a large group of polyphenolic compounds, which are ubiquitously expressed in plants. They are grouped according to their chemical structure and function into flavonols, flavones, flavan-3-ols, anthocyanins, flavanones and isoflavones. Many of flavonoids are found in fruits, vegetables and beverages. Flavonoids have been demonstrated to have advantageous effects on human health because their anti-allergic, anti-inflammatory, anti-platelet aggregation, anti-tumor and anti-oxidant behavior. This report reviews the current knowledge on the molecular mechanisms of action of flavonoids as anti-inflammatory agents and also discusses the relevant patents.

The contribution of oxidative stress in apoptosis of human-cultured astroglial cells induced by supernatants of HIV-1-infected macrophages

Apoptosis of neurons and astrocytes has been found in patientsundergoing AIDS dementia complex. We demonstrated that supernatantsfrom human primary macrophages (M/M) infected by HIV‐1 lead humanastroglial cells to oxidative stress, as shown by elevated levels ofmalondialdehyde, and then to apoptosis. Electron microscopy ofastrocytes shortly incubated with HIV‐1‐infected M/M supernatantsshowed apoptotic blebbing, cytoplasmic loss, and chromatincondensation. Apoptosis was antagonized by pretreating astrocytes withthe nonpeptidic superoxide dismutase (SOD) mimetic M40401 but notwith anti‐HIV‐1 compounds, thus showing that apoptosis of astrocytesdriven by HIV‐1‐infected M/M supernatants is mainly mediated byabnormal production of superoxide anions without relationship to HIV‐1replication in such cells. Overall results support the role ofoxidative stress mediated by HIV‐1‐infected M/M as one of the leadingcauses of neurodegeneration in patients with HIV‐1 and suggest the useof nonpeptidic SOD mimetics to counteract HIV‐1‐related neurologicaldisorders.

Identification and Characterization of the Product Encoded by ORF69 of Kaposi's Sarcoma-Associated Herpesvirus

ABSTRACT We report the identification and characterization of p33, the product of Kaposis sarcoma-associated herpesvirus (KSHV) open reading frame 69 (ORF69), a positional homolog of the conserved herpesvirus protein UL31. p33 is expressed upon induction of viral lytic cycle with early kinetics. Immunofluorescence analysis revealed that in infected cell lines, the protein is localized in the nucleus, both in dotted spots and along the nuclear membrane. Nuclear fractionation experiments showed that p33 partitions with the nuclear matrix, and both immunoblotting of purified virions and immunoelectron microscopy indicated that the novel protein is not a component of the mature virus. Following ectopic expression in KSHV-negative cells, the protein was never associated with the nuclear membrane, suggesting that p33 needs to interact with additional viral proteins to reach the nuclear rim. In fact, after cotransfection with the ORF67 gene, the KSHV positional homolog of UL34, the p33 intranuclear signal changed and the two proteins colocalized on the nuclear membrane. A similar result was obtained when ORF69 was cotransfected with BFRF1, the Epstein-Barr virus (EBV) positional homolog of UL34 and ORF67. Finally, upon cotransfection, ORF69 significantly increased nuclear membrane reduplications induced by BFRF1. The above results indicate that KSHV p33 shares many similarities with its EBV homolog BFLF2 and suggest that functional cross-complementation is possible between members of the gammaherpesvirus subfamily.