Vitamin D3 inhibits TNFα-induced latent HIV reactivation in J-LAT cells.

1,25-Dihydroxyvitamin D3 (1,25(OH)2D3) is known to suppress NF-kB activity by interfering with its pathways. The aim of this study was to investigate the ability of 1,25(OH)2D3 in reducing the reactivation of the HIV virus J-LAT cells, an established model of latently infected cells, which were treated with TNFalpha (100 ng/ml) for 2 h with or without 24 h 1,25(OH)2D3 (100 nM) pretreatment. Reactivation of HIV RNA in J-LAT was evaluated in terms of green fluorescent protein (GFP) expression. The same experimental setting was repeated on T cells from HIV-infected patients. Treatment with TNFalpha was associated with a 16 % increase in GFP+ cells and a five-fold increase in unspliced HIV RNA expression (p < 0.04). Pretreatment of J-LAT cells with 1,25(OH)2D3 for 24 h followed by TNFalpha (100 ng/ml) for 2 h reduced the percentage of GFP+ cells by 8 %; moreover, a 2.4-fold decrease in unspliced HIV RNA expression was observed (p < 0.002). In T cells from patients, treatment with TNFalpha significantly increased unspliced HIV RNA expression (sixfold increase, p < 0.02), whereas prestimulation with 1,25(OH)2D3 reduced its expression (2.5-fold decrease, p < 0.02) compared to controls.1,25(OH)2D3 is able to reduce the ability of TNFalpha to upregulate the transcription of HIV RNA from latently infected cells. These data provide further understanding of the pathogenic mechanisms regulating viral reactivation from latent reservoirs, along with new insight in viral internalization.

Induction of OAS gene family in HIV monocyte infected patients with high and low viral load.

BACKGROUND: The innate immunity plays a predominant role in the early control of HIV infection, before the induction of adaptive immune responses. The cytokine secretion operated by the CD4(+) T helper cells is able to induce a response in the innate immunity cells and significantly affect HIV-1 persistence and replication. One of the pathways activated by monocytes to restrain viral infection is the 2' -5' -oligoadenylate synthetase (OAS)/RNase L pathway. OAS is activated by dsRNA and IFNs to produce 2' -5' oligoadenylates, which are activators of RNase L. This enzyme degrades viral and cellular RNAs, thus restricting viral infection. MATERIALS AND METHODS: We analyzed a microarray dataset obtained from the NCBI Gene Expression Omnibus (GEO, http://www.ncbi.nlm.nih.gov/geo/) databank (accession number GSE18464) in order to verify the modulation of the OAS gene family in CD14 (+) monocytes isolated from 55 subjects, 22 with HIV-1 HVL (high viral load), and 22 with HIV-1 LVL (low viral load), as well as in 11 HIV-1 seronegative controls. We have validated the data on the expression levels of the OAS genes by performing real-time PCR on monocyte from a cohort of HIV infected patients (n = 20), with clinical characteristics similar to those of the patients recruited in the study present in the microarray. RESULTS: Microarray analysis showed that OAS gene family are significantly upregulated in monocyte of HIV-1 patients with HVL, as compared to LVL patients and to healthy donors. Furthermore, we showed a significant correlation between the OAS gene family and the log2 viral load and CD4 count. These results were confirmed by the in vitro validation. CONCLUSIONS: Data from this study suggest an involvement for the OAS gene family in the control of HIV-1 infection.

CD4+ T-cell gene expression of healthy donors, HIV-1 and elite controllers: Immunological chaos.

OBJECTIVES: T-cell repertoire dysfunction characterizes human immunodeficiency virus type 1 (HIV-1) infection, but the pathogenic mechanisms remain unclear. Disease progression is probably due to a profound dysregulation of Th1, Th2, Th17 and Treg patterns. The aim of this study was to analyze the features of CD4+ T cells in HIV-positive patients with different viroimmunological profile. METHODS: we used a gene expression dataset of CD4+ T cells from healthy donors, HIV+ naive patients and Elite Controllers (EC), obtained from the NCBI Gene Expression Omnibus (GEO, http://www.ncbi.nlm.nih.gov/geo/, accession number GSE18233). RESULTS: Principal Component Analysis (PCA) showed an almost complete overlap between the HIV-infected and EC patients, which cannot easily explain the different responses to HIV infection of these two group of patients. We have found that HIV patients and the EC showed an upregulation of the Th1 pro-inflammatory cytokines and chemokines, compared to the controls. Also, we have surprisingly identified IL28B, which resulted downregulated in HIV and EC compared to healthy controls. We focused attention also on genes involved in the constitution of the immunological synapse and we showed that HLA class I and II genes resulted significantly upregulated in HIV and in EC compared to the control. In addition to it, we have found the upregulation of others syncytial molecules, including LAG3, CTLA4, CD28 and CD3, assisting the formation of syncytia with APC cells. CONCLUSIONS: Understanding the mechanisms of HIV-associated immunological chaos is critical to strategically plan focused interventions.

Acceleration of SLE-like syndrome development in NZBxNZW F1 mice by beta-glucan.

Beta-glucans are naturally occurring polysaccharides that exert important immunostimulatory activities. In the present study, we evaluated whether beta-glucans could modulate the development and the course of systemic lupus erythematosus (SLE). To this aim, we employed the classical model of SLE represented by the F1 hybrid between the NZB and NZW mouse strains which develop severe lupus-like phenotypes comparable to that of SLE patients. The administration of beta-glucan was associated to a more aggressive development of the disease and a worse prognosis, as observed from the clinical, biochemical and histopathological data. This finding implies that restraint should be practised in the possible use of beta-glucans as immunomodulators in human therapy in the context of SLE.

The immunobiology of apotransferrin in type 1 diabetes.

The transferrin (Tf) family of iron binding proteins includes important endogenous modulators of the immune function that may modulate autoimmune diseases. To define more clearly the role of apotransferrin (apoTf) in type 1 diabetes we determined the impact of this protein on type 1 diabetes as investigated in islet cells, animal models and patient sera. First, we demonstrated that recombinant apoTf counteracts the cytokine-induced death of murine pancreatic islet cells. Secondly, human apoTf administration favourably influences the course of type 1 diabetes in animal models, resulting in protection against disease development that was associated with reduction of insulitis and reduced levels of proinflammatory cytokines. Finally, we confirmed that patients with newly diagnosed type 1 diabetes manifest significantly lower apoTf serum levels compared to healthy controls and patients with long-lasting disease. In conclusion, our data suggest the apoTf pivotal role in the perpetuation of type 1 diabetes pathology.

Therapeutic potential of carbon monoxide in multiple sclerosis.

Carbon monoxide (CO) is produced during the catabolism of free haem, catalyzed by haem oxygenase (HO) enzymes, and its physiological roles include vasodilation, neurotransmission, inhibition of platelet aggregation and anti-proliferative effects on smooth muscle. In vivo preclinical studies have shown that exogenously administered quantities of CO may represent an effective treatment for conditions characterized by a dysregulated immune response. The carbon monoxide-releasing molecules (CORMs) represent a group of compounds capable of carrying and liberating controlled quantities of CO in the cellular systems. This review covers the physiological and anti-inflammatory properties of the HO/CO pathway in the central nervous system. It also discusses the effects of CORMs in preclinical models of inflammation. The accumulating data discussed herein support the possibility that CORMs may represent a novel class of drugs with disease-modifying properties in multiple sclerosis.

Molecular adjuvant HMGB1 enhances anti-influenza immunity during DNA vaccination.

DNA-based vaccines, while highly immunogenic in mice, generate significantly weaker responses in primates. Therefore, current efforts are aimed at increasing their immunogenicity, which include optimizing the plasmid/gene, the vaccine formulation and method of delivery. For example, co-immunization with molecular adjuvants encoding an immunomodulatory protein has been shown to improve the antigen (Ag)-specific immune response. Thus, the incorporation of enhancing elements, such as these, may be particularly important in the influenza model in which high titered antibody (Ab) responses are critical for protection. In this regard, we compared the ability of plasmid-encoded high-mobility group box 1 protein (HMGB1), a novel cytokine in which we have previously mutated in order to increase DNA vaccine immunogenicity, with boost Ag-specific immune responses during DNA vaccination with influenza A/PR/8/34 nucleoprotein or the hemagglutinin of A novel H1N1/09. We show that the HMGB1 adjuvant is capable of enhancing adaptive effector and memory immune responses. Although Ag-specific antibodies were detected in all vaccinated animals, a greater neutralizing Ab response was associated with the HMGB1 adjuvant. Furthermore, these responses improved CD8 T+-cell effector and memory responses and provided protection against a lethal mucosal influenza A/PR/8/34 challenge. Thus, co-immunization with HMGB1 has strong in vivo adjuvant activity during the development of immunity against plasmid-encoded Ag.

Roles of the Ras/Raf/MEK/ERK pathway in leukemia therapy.

The Ras/Raf/mitogen-activated protein kinase (MEK)/extracellular signal-regulated kinase (ERK) pathway is often implicated in sensitivity and resistance to leukemia therapy. Dysregulated signaling through the Ras/Raf/MEK/ERK pathway is often the result of genetic alterations in critical components in this pathway as well as mutations at upstream growth factor receptors. Unrestricted leukemia proliferation and decreased sensitivity to apoptotic-inducing agents and chemoresistance are typically associated with activation of pro-survival pathways. Mutations in this pathway and upstream signaling molecules can alter sensitivity to small molecule inhibitors targeting components of this cascade as well as to inhibitors targeting other key pathways (for example, phosphatidylinositol 3 kinase (PI3K)/phosphatase and tensin homologue deleted on chromosome 10 (PTEN)/Akt/mammalian target of rapamycin (mTOR)) activated in leukemia. Similarly, PI3K mutations can result in resistance to inhibitors targeting the Ras/Raf/MEK/ERK pathway, indicating important interaction points between the pathways (cross-talk). Furthermore, the Ras/Raf/MEK/ERK pathway can be activated by chemotherapeutic drugs commonly used in leukemia therapy. This review discusses the mechanisms by which abnormal expression of the Ras/Raf/MEK/ERK pathway can contribute to drug resistance as well as resistance to targeted leukemia therapy. Controlling the expression of this pathway could improve leukemia therapy and ameliorate human health.

Targeting the translational apparatus to improve leukemia therapy: roles of the PI3K/PTEN/Akt/mTOR pathway.

It has become apparent that regulation of protein translation is an important determinant in controlling cell growth and leukemic transformation. The phosphoinositide 3-kinase (PI3K)/phosphatase and tensin homologue deleted on chromosome ten (PTEN)/Akt/mammalian target of rapamycin (mTOR) pathway is often implicated in sensitivity and resistance to therapy. Dysregulated signaling through the PI3K/PTEN/Akt/mTOR pathway is often the result of genetic alterations in critical components in this pathway as well as mutations at upstream growth factor receptors. Furthermore, this pathway is activated by autocrine transformation mechanisms. PTEN is a critical tumor suppressor gene and its dysregulation results in the activation of Akt. PTEN is often mutated, silenced and is often haploinsufficient. The mTOR complex1 (mTORC1) regulates the assembly of the eukaryotic initiation factor4F complex, which is critical for the translation of mRNAs that are important for cell growth, prevention of apoptosis and transformation. These mRNAs have long 5'-untranslated regions that are G+C rich, rendering them difficult to translate. Elevated mTORC1 activity promotes the translation of these mRNAs via the phosphorylation of 4E-BP1. mTORC1 is a target of rapamycin and novel active-site inhibitors that directly target the TOR kinase activity. Although rapamycin and novel rapalogs are usually cytostatic and not cytotoxic for leukemic cells, novel inhibitors that target the kinase activities of PI3K and mTOR may prove more effective for leukemia therapy.

Prevention of clinical and histological signs of proteolipid protein (PLP)-induced experimental allergic encephalomyelitis (EAE) in mice by the water-soluble carbon monoxide-releasing molecule (CORM)-A1.

We have evaluated the effects of the carbon monoxide-releasing molecule CORM-A1 [Na(2) (BH(3) CO(2) ); ALF421] on the development of relapsing-remitting experimental allergic encephalomyelitis (EAE) in SJL mice, an established model of multiple sclerosis (MS). The data show that the prolonged prophylactic administration of CORM-A1 improves the clinical and histopathological signs of EAE, as shown by a reduced cumulative score, shorter duration and a lower cumulative incidence of the disease as well as milder inflammatory infiltrations of the spinal cords. This study suggests that the use of CORM-A1 might represent a novel therapeutic strategy for the treatment of multiple sclerosis.

Specific and strain-independent effects of dexamethasone in the prevention and treatment of experimental autoimmune encephalomyelitis in rodents.

Experimental autoimmune encephalomyelitis in rodents (EAE) is a generally accepted in vivo model for immunopathogenic mechanisms underlying multiple sclerosis (MS). There are, however, different forms of rodent EAE, and therapeutic regimens may affect these forms differently. We have therefore tested the effects of dexamethasone (Dex) and found that both prophylactic and early therapeutic regimens were effective in suppressing the development of monophasic EAE in myelin basic protein-immunized Lewis rats, the relapsing-remitting forms of EAE induced in SJL mice by proteolipid protein and in DA rats by syngeneic spinal cord homogenate, and the progressive forms induced in C57BL/6 and DBA/1 mice by immunization with myelin oligodendrocyte glycoprotein. In addition, prophylactically administered Dex suppressed histological and immunological features of EAE such as spinal cord infiltration of inflammatory cells and the increased frequency of autoantigen-specific interferon-gamma-secreting lymph node mononuclear cells. The present data reproduced in rodent EAE models some of the beneficial effects observed with glucocorticoids in MS. This strengthens the validity of these five models as in vivo predictors of drug efficacy in at least some variants of human MS. Better understanding of the clinical and immunopharmacologic features of these models might prove useful when testing new drug candidates for MS treatment.