Tripartite Motif 22 and Class II Transactivator Restriction Factors: Unveiling Their Concerted Action against Retroviruses

Coevolution of the three basic mechanisms of immunity, intrinsic, innate and adaptive, is a constant feature of the host defense against pathogens. Within this frame, a peculiar role is played by restriction factors (RFs), elements of intrinsic immunity that interfere with viral life cycle. Often considered as molecules whose specific functions are distinct and unrelated among themselves recent results indicate instead, at least for some of them, a concerted action against the pathogen. Here we review recent findings on the antiviral activity of tripartite motif 22 (TRIM22) and class II transactivator (CIITA), first discovered as human immunodeficiency virus 1 RFs, but endowed with general antiviral activity. TRIM22 and CIITA provide the first example of cellular proteins acting together to potentiate their intrinsic immunity.

Tumor Immunology meets…Immunology: Modified cancer cells as professional APC for priming naïve tumor-specific CD4+ T cells

Although recent therapeutic approaches have revitalized the enthusiasm of the immunological way to combat cancer, still the comprehension of immunity against tumors is largely incomplete. Due to their specific function, CD8+ T cells with cytolytic activity (CTL) have attracted the attention of most investigators because CTL are considered the main effectors against tumor cells. Nevertheless, CTL activity and persistence is largely dependent on the action of CD4+ T helper cells (TH). Thus establishment of tumor-specific TH cell response is key to the optimal response against cancer. Here we describe emerging new strategies to increase the TH cell recognition of tumor antigens. In particular, we review recent data indicating that tumor cells themselves can act as surrogate antigen presenting cells for triggering TH response and how these findings can help in constructing immunotherapeutic protocols for anti-cancer vaccine development.

Tripartite Motif-Containing Protein 22 Interacts with Class II Transactivator and Orchestrates Its Recruitment in Nuclear Bodies Containing TRIM19/PML and Cyclin T1

Among interferon (IFN) inducible antiviral factors both tripartite motif-containing protein 22 (TRIM22) and class II transactivator (CIITA) share the capacity of repressing human immunodeficiency virus type 1 (HIV-1) proviral transcription. TRIM22 is constitutively expressed in a subset of U937 cell clones poorly permissive to HIV-1 replication, whereas CIITA has been shown to inhibit virus multiplication in both T lymphocytic and myeloid cells, including poorly HIV-1 permissive U937 cells, by suppressing Tat-mediated transactivation of HIV-1 transcription. Therefore, we tested whether TRIM22 and CIITA could form a nuclear complex potentially endowed with HIV-1 repressive functions. Indeed, we observed that TRIM22, independent of its E3 ubiquitin ligase domain, interacts with CIITA and promotes its recruitment into nuclear bodies. Importantly, TRIM19/promyelocytic leukemia (PML) protein, another repressor of HIV-1 transcription also acting before proviral integration, colocalize in these nuclear bodies upon TRIM22 expression induced by IFN-γ. Finally, tTRIM22 nuclear bodies also contained CyclinT1, a crucial elongation factor of HIV-1 primary transcripts. These findings show that TRIM22 nuclear bodies are a site of recruitment of factors crucial for the regulation of HIV-1 transcription and highlight the potential existence of a concerted action between TRIM22, CIITA, and TRIM19/PML to maintain a state of proviral latency, at least in myeloid cells.

CIITA-driven MHC class II expressing tumor cells can efficiently prime naive CD4+ TH cells in vivo and vaccinate the host against parental MHC-II-negative tumor cells

Our previous studies showed that non-immunogenic H-2^d tumor cells of distinct epithelial histotypes can become highly immunogenic, induce a protective CD4⁺ T cell response and vaccinate the animals against parental MHC-II-negative cells if they are rendered MHC class II-positive by stable transfection with the Air-1-encoded MHC-II transcriptional activator CIITA. These studies did not establish, however, whether tumor immunity was the consequence of a direct priming of naive CD4⁺ T lymphocytes by CIITA-driven MHC-II-expressing tumor cells or by MHC-II-tumor antigen complexes engulfed by dendritic cells (DC) and exposed on the surface of these professional antigen presenting cells (APC). In the present investigation, we provide definitive evidence that CIITA-tumor cells are the crucial APC in vivo for CD4⁺ T cell priming. By using a transgenic H-2^b mouse model, the CD11c.DTR C57BL/6 mice, in which DC can be functionally deleted by administration of diphteria toxin, we show that CIITA-tumor cells of two distinct histotypes can be rejected or strongly retarded in their growth in DC-deleted mice. To rule out that in absence of DC, other professional APC could prime naive CD4⁺ T cells, we deleted the macrophages in CD11c.DTR C57BL/6 mice by administration of liposome Clodronate and still obtained rejection or strong retardation in tumor growth of CIITA-tumor cells. Our results challenge the diffuse belief that non-professional APC cannot efficiently prime naive T cells in vivo. Moreover, the demonstration of the general validity of our approach in different genetic backgrounds may open a way for new strategies of antitumor treatment in clinical settings.

Abstract A014: CIITA dependent MHC class II IA expression in tumor cells triggers CD4 T cell protective and long lasting antitumor immunity

We previously demonstrated the generation of a CD4 T cell-specific long lasting anti-tumor immune response in the H-2d BALB/c mouse model by using tumor cells that have been genetically modified with CIITA to express MHC-II I-E and I-A molecules. We have now investigated the pertinence of this approach in the H-2b C57BL/6 mouse model despite the defect in their I-Eα gene and thus the lack of expression of I-E subset. To this purpose we injected in vivo the CIITA-driven I-A-only MHC-II-positive LLC (lewis Lung Carcinoma) and MC38 colon carcinoma in the C57BL/6 mice and their growth rate along with the recipient's immune response were analyzed. The CIITA-transfected, MHC-II-positive tumor cells were either completely rejected or showed a significant growth retardation compared to the MHC-II-negative parental tumor. The protected mice were re-injected with the parental tumors and a complete rejection was obtained proving that a specific long lasting immune response was triggered by the CIITA-transfected tumors. Furthermore, total splenocytes or purified CD4+, CD8+ T cells and B cells were transferred from the vaccinated recipients to naïve recipients that were co-injected with the parental tumor cells and the results showed that CD4+ TH cells were the main effectors of the immune response against the tumor cells. Interestingly, similar results were obtained in C57BL/6-DOG transgenic mice whose dendritic cells could be conditionally ablated after administration of Diphteria toxin. These results demonstrate the validity of triggering a specific, long-lasting anti-tumor immune response using CIITA-driven MHC class II positive tumor cells of different MHC haplotype as stimulators. Importantly, the results establish that expression of a single MHC-II restriction element, I-A, in tumor cells is sufficient to trigger CD4+ TH cell protective immune response, strongly suggesting that the relevant tumor-associated antigenic repertoire can be displayed without the need of the I-E restriction element. Finally, these results strongly suggest that CIITA-modified tumor cells can act as antigen presenting cells in vivo to prime naïve CD4+ TH cells against tumor antigens.

Citation Format: Farah Bou Nasser Eddine, Greta Forlani, Giovanna Tosi, Roberto S. Accolla. CIITA dependent MHC class II IA expression in tumor cells triggers CD4 T cell protective and long lasting antitumor immunity [abstract]. In: Proceedings of the Second CRI-CIMT-EATI-AACR International Cancer Immunotherapy Conference: Translating Science into Survival; 2016 Sept 25-28; New York, NY. Philadelphia (PA): AACR; Cancer Immunol Res 2016;4(11 Suppl):Abstract nr A014.

THE POTENTIAL OF LOW-COST RPAS FOR MULTI-VIEW RECONSTRUCTION OF SUB-VERTICAL ROCK FACES

The current work investigates the potential of two low-cost off-the-shelf quadcopters for multi-view reconstruction of sub-vertical rock faces. The two platforms used are a DJI Phantom 1 equipped with a Gopro Hero 3+ Black and a DJI Phantom 3 Professional with integrated camera. The study area is a small sub-vertical rock face. Several flights were performed with both cameras set in time-lapse mode. Hence, images were taken automatically but the flights were performed manually as the investigated rock face is very irregular which required manual adjustment of the yaw and roll for optimal coverage. The digital images were processed with commercial SfM software packages. Several processing settings were investigated in order to find out the one providing the most accurate 3D reconstruction of the rock face. To this aim, all 3D models produced with both platforms are compared to a point cloud obtained with a terrestrial laser scanner. Firstly, the difference between the use of coded ground control targets and the use of natural features was studied. Coded targets generally provide the best accuracy, but they need to be placed on the surface, which is not always possible, as sub-vertical rock faces are not easily accessible. Nevertheless, natural features can provide a good alternative if wisely chosen as shown in this work. Secondly, the influence of using fixed interior orientation parameters or self-calibration was investigated. The results show that, in the case of the used sensors and camera networks, self-calibration provides better results. To support such empirical finding, a numerical investigation using a Monte Carlo simulation was performed.

The MHC-II transactivator CIITA inhibits Tat function and HIV-1 replication in human myeloid cells

Background

We previously demonstrated that the HLA class II transactivator CIITA inhibits HIV-1 replication in T cells by competing with the viral transactivator Tat for the binding to Cyclin T1 subunit of the P-TEFb complex. Here, we analyzed the anti-viral function of CIITA in myeloid cells, another relevant HIV-1 target cell type. We sinvestigated clones of the U937 promonocytic cell line, either permissive (Plus) or non-permissive (Minus) to HIV-1 replication. This different phenotype has been associated with the expression of TRIM22 in U937 Minus but not in Plus cells.

Methods

U937 Plus cells stably expressing CIITA were generated and HLA-II positive clones were selected by cell sorting and cloning. HLA and CIITA proteins were analyzed by cytofluorometry and western blotting, respectively. HLA-II DR and CIITA mRNAs were quantified by qRT-PCR. Tat-dependent transactivation was assessed by performing the HIV-1 LTR luciferase gene reporter assay. Cells were infected with HIV-1 and viral replication was evaluated by measuring the RT activity in culture supernatants.

Results

CIITA was expressed only in HLA-II-positive U937 Minus cells, and this was strictly correlated with inhibition of Tat-dependent HIV-1 LTR transactivation in Minus but not in Plus cells. Overexpression of CIITA in Plus cells restored the suppression of Tat transactivation, confirming the inhibitory role of CIITA. Importantly, HIV-1 replication was significantly reduced in Plus-CIITA cells with respect to Plus parental cells. This effect was independent of TRIM22 as CIITA did not induce TRIM22 expression in Plus-CIITA cells.

Conclusions

U937 Plus and Minus cells represent an interesting model to study the role of CIITA in HIV-1 restriction in the monocytic/macrophage cell lineage. The differential expression of CIITA in CIITA-negative Plus and CIITA-positive Minus cells correlated with their capacity to support or not HIV-1 replication, respectively. In Minus cells CIITA targeted the viral transactivator Tat to inhibit HIV-1 replication. The generation of Plus-CIITA cells was instrumental to demonstrate the specific contribution of CIITA in terms of inhibition of Tat activity and HIV-1 restriction, independently from other cellular factors, including TRIM22. Thus, CIITA acts as a general restriction factor against HIV-1 not only in T cells but also in myeloid cells.

Costs associated with emergency care and hospitalization for severe hypoglycemia

BACKGROUND AND AIMS

We aimed to determine the direct economic cost of the management of severe hypoglycemia among people with diabetes in Italy.

METHODS AND RESULTS

Data of cases with an acceptance diagnosis of hypoglycemia between January 2011 and June 2012 were collected in 46 Emergency Departments (EDs). Emergency care costs were computed by estimating the average cost per ambulance service, ED visit and short-term (<24 h) observation period. Hospitalization expenditure was estimated using the average cost reimbursed by the Italian healthcare system for hospital admission per patient with diabetes in a specific hospital ward. We retrieved 3516 hypoglycemic episodes occurring in subjects with diabetes. Half the cases (51.8%) required referral to EDs by means of the emergency ambulance services. A total of 1751 cases (49.8%) received an ED visit followed by discharge; 604 cases (17.2%) received a short-term observation period; 1161 (33.1%) were hospitalized. Unit costs for emergency care management were estimated at €205 for an ambulance call, €23 for an ED visit, and €220 for a short-term observation. The mean hospitalization cost was estimated at €5317; the average cost per each severe hypoglycemic event totaled €1911. From a base case assumption, the total direct cost of severe hypoglycemia in patients with diabetes in Italy was estimated to be approximately €23 million per year.

CONCLUSION

Severe hypoglycemia in patients with diabetes constitutes a remarkable economic burden for national healthcare systems. Measures for preventing hypoglycemia are mandatory in diabetes management programs considering the impact on patients and on health spending.

Abstract B047: Adequate Antigen Availability (AAA) in antitumor immunity: Definition and consequences for novel strategies of tumor prevention and antitumor treatment

Present immunopreventive and immunotherapeutic approaches against cancer suffer from the limitation of being not “sterilizing” procedures, as very poor protection against the tumor is obtained. Thus, newly conceived anti-tumor strategies of intervention are urgently needed. Here we introduce the concept of Adequate Antigen Availability (AAA) defined as the optimal tumor antigen dose and related antigen processing and MHC class II-restricted presentation necessary to trigger efficient tumor-specific TH cells (1). We will present results on a preventive anti-tumor vaccination system that consists in injecting tumor cells genetically modified to constitutively express MHC class II molecules by transfecting the MHC-II transcriptional activator CIITA. AAA is generated by the function of tumor's newly expressed MHC-II molecules to present tumor-associated antigens to tumor-specific CD4+ TH cells. We will show that tumor rejection against the CIITA-transfected neoplastic cells is brought about by the generation of persistent anti-tumor TH cell memory, responsible of protecting the animals from subsequent challenges with parental, untransfected tumor cells. This approach has been validated in tumor cells of different histotypic origin and of distinct MHC genotype (H-2d and H-2b). Importantly, the anti-tumor TH cell response modifies the tumor microenvironment, favouring the infiltration of CD4+ TH cells, CD8+ cytolytic T cells and granulocytes and dramatically reducing both intratumoral and lymphnode infiltration of regulatory T cells (Tregs) and myeloid-derived suppressor cells (MDSC). Thus the optimal initiation of the adaptive immune response, dictated by AAA, is sufficient to reorient the tumor microenvironment from a pro-tumor to an anti-tumor microenvironment. Our approach is, at present, applied to human clinical setting in hepatocellular carcinomas (2) whereby human tumor cells are rendered HLA class II-positive by CIITA genetic transfer with the aim to purify and sequence immunogenically relevant HLA class II-bound tumor–associated antigenic (TAA) peptides. In conjunction with similarly derived HLA class I-restricted TAA peptides, they will be the basis for the construction of a multi-peptide, multi-epitope vaccine that can target both CD4+ TH and CD8+ CTL anti-tumor responses.

References:

1. Accolla RS, Lombardo L, Abdallah R, Raval G, Forlani G, Tosi G. Boosting the MHC class II-restricted tumor antigen presentation to CD4+ T helper cells: a critical issue for triggering protective immunity and re-orienting the tumor microenvironment toward an anti-tumor state. Front Oncol. 2014 Feb 18;4:32

2. Hepavac, Cancer Vaccine Development for Hepatocellular Carcinoma. FP7-HEALTH-2013, Collaborative Project, Project number: 602893

Citation Format: Roberto S. Accolla, Greta Forlani, Giovanna Tosi. Adequate Antigen Availability (AAA) in antitumor immunity: Definition and consequences for novel strategies of tumor prevention and antitumor treatment. [abstract]. In: Proceedings of the CRI-CIMT-EATI-AACR Inaugural International Cancer Immunotherapy Conference: Translating Science into Survival; September 16-19, 2015; New York, NY. Philadelphia (PA): AACR; Cancer Immunol Res 2016;4(1 Suppl):Abstract nr B047.

Abstract B048: The MHC class II transactivator CIITA inhibits the persistent activation of NF-kB by Human T cell Lymphotropic Virus type-1 Tax-1 oncoprotein

Human T cell Lymphotropic Virus type-1 (HTLV-1) Tax-1 protein, a key mediator of HTLV-1-induced T-cell transformation, deregulates diverse cell-signalling pathways. Among them, the NF-kB pathway is constitutively activated by Tax-1, which binds to NF-kB family members and activates the IkB-kinase (IKK). Upon phosphorylation-dependent degradation of IkB, NF-kB migrates into the nucleus and mediates Tax-1-stimulated gene expression. We show that CIITA, the transcriptional regulator of Major Histocompatibility Complex Class II genes, inhibits the activation of the canonical NF-kB pathway by Tax-1 and map the region mediating this effect. CIITA affects the subcellular localization of Tax-1, which is mostly retained in the cytoplasm, and this correlates with an impaired migration of RelA into the nucleus. Cytoplasmic and nuclear CIITA mutants reveal that CIITA exploits different strategies to suppress Tax-1-mediated NF-kB activation in both subcellular compartments. CIITA interacts with Tax-1 without preventing Tax-1 binding to both IKKg and RelA. Nevertheless, CIITA affects Tax-1-induced IKK activity causing the retention of the inactive p50/RelA/IkB complex in the cytoplasm. Nuclear CIITA associates with Tax-1/RelA in nuclear bodies blocking the activation of NF-kB-responsive genes by Tax-1. Thus, CIITA inhibits critical cytoplasmic and nuclear steps of Tax-1-mediated NF-kB activation. These results, together with our previous finding that CIITA acts as a restriction factor inhibiting Tax-1-promoted HTLV-1 gene expression and replication, indicate that CIITA is a versatile molecule that might also counteract Tax-1 transforming activity. Unveiling the molecular basis of CIITA-mediated inhibition of Tax-1 functions may be important in defining new strategies to control HTLV-1 spreading and oncogenic potential.

Citation Format: Greta Forlani, Rawan Abdallah, Roberto S. Accolla, Giovanna Tosi. The MHC class II transactivator CIITA inhibits the persistent activation of NF-kB by Human T cell Lymphotropic Virus type-1 Tax-1 oncoprotein. [abstract]. In: Proceedings of the CRI-CIMT-EATI-AACR Inaugural International Cancer Immunotherapy Conference: Translating Science into Survival; September 16-19, 2015; New York, NY. Philadelphia (PA): AACR; Cancer Immunol Res 2016;4(1 Suppl):Abstract nr B048.

Localization, quantification and interaction with host factors of endogenous HTLV-1 HBZ protein in infected cells and ATL

BACKGROUND

Human T cell lymphotropic virus type 1 (HTLV-1) is the etiological agent of a severe form of neoplasia designated Adult T cell Leukaemia (ATL). It is widely accepted that the viral transactivator Tax-1 is the major viral product involved in the onset, but not in the maintenance, of neoplastic phenotype, as only 30-40% of ATL cells express Tax-1. It has been recently demonstrated that HBZ (HTLV-1 bZIP factor), a protein encoded by the minus strand of HTLV-1 genome, constantly expressed in infected cells and in ATL tumor cells, is also involved in the pathogenesis of leukaemia. The full role played by HBZ in oncogenesis is not clarified in detail also because of the limited availability of tools to assess quantitative expression, subcellular location and interaction of HBZ with host factors in ATL.

RESULTS

By the use of the first reported monoclonal antibody against HBZ, 4D4-F3, generated in our laboratory it has been possible to carefully assess for the first time the above parameters in HTLV-1 chronically infected cells and, most importantly, in fresh leukemic cells from patients. Endogenous HBZ is expressed in speckle-like structures localized in the nucleus. The calculated number of endogenous HBZ molecules varies between 17.461 and 39.615 molecules per cell, 20- to 50-fold less than the amount expressed in HBZ transfected cells used by most investigators to assess the expression, function and subcellular localization of the viral protein. HBZ interacts in vivo with p300 and JunD and co-localizes only partially, and depending on the amount of expressed HBZ, not only with p300 and JunD but also with CBP and CREB2.

CONCLUSIONS

The possibility to study endogenous HBZ in detail may significantly contribute to a better delineation of the role of HBZ during HTLV-1 infection and cellular transformation.

Differential accumulation of γ-aminobutyric acid in elicited cells of two rice cultivars showing contrasting sensitivity to the blast pathogen

Intracellular free amino acid pools were quantified in suspension cultured cells of a blast-sensitive and a blast-resistant rice genotype at increasing times after treatment with Magnaporthe oryzae cell wall hydrolysates. Besides some expected variations in free phenylalanine, a remarkable early increase of γ-aminobutyric acid (GABA) levels was evident in both cultivars. Glutamate decarboxylase activity and protein levels were unaffected. GABA homeostasis was recovered in the sensitive cultivar 48 h after the treatment. In contrast, a further GABA accumulation and a general increase of most amino acids was found at this later stage in the resistant genotype, which showed a larger decrease in cell viability as a consequence of elicitor addition. Data support a recently hypothesised role of GABA metabolism in the plant response to fungal pathogens.

Transition from pediatric to adult care. eight years after the transition from pediatric to adult diabetes care: metabolic control, complications and associated diseases

BACKGROUND

Transition from pediatric to adult care is a critical process in the life of patients with diabetes.

AIM

Primary aim of the study was to compare the metabolic control between pediatric care and adult care at least 5 years in a group of patients with type 1 diabetes mellitus (T1DM). Secondary aim was to evaluate the presence of complications, associated diseases and psychological-psychiatric disorders.

SUBJECTS AND METHODS

We obtained data from 73 % (69/94) patients (current mean age 34 years) transferred to local adult centers between 1985 and 2005 at a mean age of 23.8 years. Data were collected for HbA1c, diabetic complications and associated diseases.

RESULTS

Mean HbA1c did not change during the pediatric, transition and adult period [8.4 ± 1.8 % (68 ± 18 mmol/mol), 8.3 ± 1.4 % (67 ± 15 mmol/mol) and 8.4 ± 1.3 % (68 ± 14 mmol/mol), respectively]. 13 patients dropped out, after 2-12 years since transition, and their HbA1c mean value at transition was 10.4 %. After a mean of 25.9 years of disease, 35/69 patients (50.7 %) showed retinopathy, and 12/69 patients (17.3 %) nephropathy. Thyroid diseases were the most frequent associated diseases (18.3 %), followed by depression (11.2 %) and benign neoplasms (9.8 %). Drug or alcohol addictions were present in four cases (5.6 %).

CONCLUSIONS

After a mean follow-up of 8 years metabolic control after transition did not change significantly in patients constantly attending to adult care centre. Patients with diabetes onset between 20 and 40 years ago were free from complications in 50 % of cases when considering retinopathy and in more than 80 % considering nephropathy. Thyroid problems were the most common associated diseases. Poor metabolic control at transition is associated with higher risk of drop-out and psychosocial morbidity.

Boosting the MHC Class II-Restricted Tumor Antigen Presentation to CD4+ T Helper Cells: A Critical Issue for Triggering Protective Immunity and Re-Orienting the Tumor Microenvironment Toward an Anti-Tumor State

Although the existence of an immune response against tumor cells is well documented, the fact that tumors take off in cancer patients indicates that neoplastic cells can circumvent this response. Over the years many investigators have described strategies to rescue the anti-tumor immune response with the aim of creating specific and long-lasting protection against the disease. When exported to human clinical settings, these strategies have revealed in most cases a very limited, if any, positive outcome. We believe that the failure is mostly due to the inadequate triggering of the CD4+ T helper (TH) cell arm of the adaptive immunity, as TH cells are necessary to trigger all the immune effector mechanisms required to eliminate tumor cells. In this review, we focus on novel strategies that by stimulating MHC class II-restricted activation of TH cells generate a specific and persistent adaptive immunity against the tumor. This point is of critical importance for both preventive and therapeutic anti-tumor vaccination protocols, because adaptive immunity with its capacity to produce specific, long-lasting protection and memory responses is indeed the final goal of vaccination. We will discuss data from our as well as other laboratories which strongly suggest that triggering a specific and persistent anti-tumor CD4+ TH cell response stably modify not only the tumor microenvironment but also tumor-dependent extratumor microenvironments by eliminating and/or reducing the blood-derived tumor infiltrating cells that may have a pro-tumor growth function such as regulatory CD4+/CD25+ T cells and myeloid-derived-suppressor cells. Within this frame, therefore, we believe that the establishment of a pro-tumor environment is not the cause but simply the consequence of the tumor strategy to primarily counteract components of the adaptive cellular immunity, particularly TH lymphocytes.

Investigating human T cell lymphotropic retrovirus (HTLV) Tax function with molecular and immunophenotypic techniques

Human T cell Lymphotropic Viruses 1 and 2 (HTLV-1 and HTLV-2) are the first described human retroviruses. HTLV-1 is the causative agent of an aggressive malignancy of CD4+ T lymphocytes named adult T-cell leukemia/lymphoma (ATLL) and of a chronic neurological disease known as HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP). HTLV-2 shares many similarities with HTLV-1, but displays lower or absent association to diseases. Among the proteins encoded by HTLVs, the viral transactivator Tax exerts an essential role in viral transcription as well as in cell transformation. Different experimental methods to study Tax activity on HTLV-LTR promoter and Tax subcellular distribution are described. Emphasis is given to the functional and physical interaction between Tax-1/Tax-2 and cellular cofactors which may have an impact on the infectivity process of the HTLVs and on the capacity of cell transformation.

The MHC-II transactivator CIITA, a restriction factor against oncogenic HTLV-1 and HTLV-2 retroviruses: similarities and differences in the inhibition of Tax-1 and Tax-2 viral transactivators

The activation of CD4(+) T helper cells is strictly dependent on the presentation of antigenic peptides by MHC class II (MHC-II) molecules. MHC-II expression is primarily regulated at the transcriptional level by the AIR-1 gene product CIITA (class II transactivator). Thus, CIITA plays a pivotal role in the triggering of the adaptive immune response against pathogens. Besides this well known function, we recently found that CIITA acts as an endogenous restriction factor against HTLV-1 (human T cell lymphotropic virus type 1) and HTLV-2 oncogenic retroviruses by targeting their viral transactivators Tax-1 and Tax-2, respectively. Here we review our findings on CIITA-mediated inhibition of viral replication and discuss similarities and differences in the molecular mechanisms by which CIITA specifically counteracts the function of Tax-1 and Tax-2 molecules. The dual function of CIITA as a key regulator of adaptive and intrinsic immunity represents a rather unique example of adaptation of host-derived factors against pathogen infections during evolution.

Moderate alcohol use and health: a consensus document

AIMS

The aim of this consensus paper is to review the available evidence on the association between moderate alcohol use, health and disease and to provide a working document to the scientific and health professional communities.

DATA SYNTHESIS

In healthy adults and in the elderly, spontaneous consumption of alcoholic beverages within 30 g ethanol/d for men and 15 g/d for women is to be considered acceptable and do not deserve intervention by the primary care physician or the health professional in charge. Patients with increased risk for specific diseases, for example, women with familiar history of breast cancer, or subjects with familiar history of early cardiovascular disease, or cardiovascular patients should discuss with their physician their drinking habits. No abstainer should be advised to drink for health reasons. Alcohol use must be discouraged in specific physiological or personal situations or in selected age classes (children and adolescents, pregnant and lactating women and recovering alcoholics). Moreover, the possible interactions between alcohol and acute or chronic drug use must be discussed with the primary care physician.

CONCLUSIONS

The choice to consume alcohol should be based on individual considerations, taking into account the influence on health and diet, the risk of alcoholism and abuse, the effect on behaviour and other factors that may vary with age and lifestyle. Moderation in drinking and development of an associated lifestyle culture should be fostered.

Molecular and cellular correlates of the CIITA-mediated inhibition of HTLV-2 Tax-2 transactivator function resulting in loss of viral replication

Background

MHC class II transactivator CIITA inhibits the function of HTLV-2 Tax-2 viral transactivator and, consequently, the replication of the virus in infected cells. Moreover overexpression of the nuclear factor NF-YB, that cooperates with CIITA for the expression of MHC class II genes, results also in inhibition of Tax-2 transactivation. The purpose of this investigation was to assess the cellular and molecular basis of the CIITA-mediated inhibition on Tax-2, and the relative role of NF-YB in this phenomenon.

Methods

By co-immunoprecipitation of lysates from 293T cells cotransfected with CIITA or fragments of it, and Tax-2 it was assessed whether the two factors interact in vivo. A similar approach was used to assess Tax-2-NF-YB interaction. In parallel, deletion fragments of CIITA were tested for the inhibition of Tax-2-dependent HTLV-2 LTR-luciferase transactivation. Subcellular localization of CIITA and Tax-2 was investigated by immunofluorescence and confocal microscopy.

Results

CIITA and Tax-2 interact in vivo through at least two independent regions, at the 1-252 N-term and at the 410-1130 C-term, respectively. Interestingly only the 1-252 N-term region mediates Tax-2 functional inhibition. CIITA and Tax-2 are localized both in the cytoplasm and in the nucleus, when separately expressed. Instead, when coexpressed, most of Tax-2 colocalize with CIITA in cytoplasm and around the nuclear membrane. The Tax-2 minor remaining nuclear portion also co-localizes with CIITA. Interestingly, when CIITA nucleus-cytoplasm shuttling is blocked by leptomycin B treatment, most of the Tax-2 molecules are also blocked and co-localize with CIITA in the nucleus, suggesting that CIITA-Tax-2 binding does not preclude Tax-2 entry into the nucleus.

Finally, the nuclear factor NF-YB, also strongly binds to Tax-2. Notably, although endogenous NF-YB does not inhibit Tax-2-dependent HTLV-2 LTR transactivation, it still binds to Tax-2, and in presence of CIITA, this binding seems to increase.

Conclusions

These results strongly suggest that CIITA inhibit Tax-2 by binding the viral transactivator both directly or through a tripartite interaction with NF-YB in. CIITA is therefore a viral restriction factor for HTLV-2 and this open the possibility to control HTLV-2 viral replication and spreading by the controlled induction of CIITA in infected cells