IFI16 senses DNA forms of the lentiviral replication cycle and controls HIV-1 replication.

Replication of lentiviruses generates different DNA forms, including RNA:DNA hybrids, ssDNA, and dsDNA. Nucleic acids stimulate innate immune responses, and pattern recognition receptors detecting dsDNA have been identified. However, sensors for ssDNA have not been reported, and the ability of RNA:DNA hybrids to stimulate innate immune responses is controversial. Using ssDNAs derived from HIV-1 proviral DNA, we report that this DNA form potently induces the expression of IFNs in primary human macrophages. This response was stimulated by stem regions in the DNA structure and was dependent on IFN-inducible protein 16 (IFI16), which bound immunostimulatory DNA directly and activated the stimulator of IFN genes -TANK-binding kinase 1 - IFN regulatory factors 3/7 (STING-TBK1-IRF3/7) pathway. Importantly, IFI16 colocalized and associated with lentiviral DNA in the cytoplasm in macrophages, and IFI16 knockdown in this cell type augmented lentiviral transduction and also HIV-1 replication. Thus, IFI16 is a sensor for DNA forms produced during the lentiviral replication cycle and regulates HIV-1 replication in macrophages.

Hepatitis C therapy with interferon-α and ribavirin reduces CD4 T-cell-associated HIV-1 DNA in HIV-1/hepatitis C virus-coinfected patients.

Combined treatment with interferon alpha (IFN-α) and ribavirin (RBV) can effectively cure HCV infection in a significant proportion of patients, but effects of this regimen on cellular reservoirs for human immunodeficiency virus type 1 (HIV-1) are unknown. Here, we show that treatment with IFN-α/RBV led to a moderate but significant and sustained decline of HIV-1 DNA in CD4 T cells from HIV-1/hepatitis C virus-coinfected patients receiving highly active antiretroviral therapy (n = 12). However, in vitro experiments failed to demonstrate an effect of pharmacological doses of IFN-α on HIV-1 reactivation. Together, these data suggest that treatment with IFN-α/RBV can moderately reduce the reservoir of HIV-1-infected CD4 T cells that persists despite suppressive antiretroviral therapy.

Characterization of HIV-1 infection and innate sensing in different types of primary human monocyte-derived macrophages.

Macrophages play an important role in human immunodeficiency virus (HIV) pathogenesis and contribute to establishment of a viral reservoir responsible for continuous virus production and virus transmission to T cells. In this study, we investigated the differences between various monocyte-derived macrophages (MDMs) generated through different differentiation protocols and evaluated different cellular, immunological, and virological properties. We found that elevated and persistent HIV-1 pWT/BaL replication could be obtained only in MDMs grown in RPMI containing macrophage colony-stimulating factor (M-CSF). Interestingly, this MDM type was also most responsive to toll-like receptor stimulation. By contrast, all MDM types were activated to a comparable extent by intracellular DNA, and the macrophage serum-free medium-(Mac-SFM-)differentiated MDMs responded strongly to membrane fusion through expression of CXCL10. Finally, we found that HIV infection of RPMI/M-CSF-differentiated MDMs induced low-grade expression of two interferon-stimulated genes in some donors. In conclusion, our study demonstrates that the differentiation protocol used greatly influences the ability of MDMs to activate innate immune reactions and support HIV-1 replication. Paradoxically, the data show that the MDMs with the strongest innate immune response were also the most permissive for HIV-1 replication.

Kinetics of Torque Teno virus in heart transplant patients.

End-stage heart failure often requires heart transplantation as a life-prolonging treatment. Immunosuppressive therapy is necessary to avoid rejection, but is associated with serious adverse effects. New approaches are needed to monitor immune function in heart transplant patients. We here report the kinetics of Torque Teno Virus (TTV) after transplantation in a large cohort of heart transplant patients and examine its possible role in predicting rejection. We included 106 patients from Aarhus University Hospital and Oslo University Hospital. Patients were followed for 3 years with clinical assessments, biopsies, TTV measurements, and flowcytometric phenotyping. We observed TTV levels reaching a maximum 3 months after transplantation for all 106 patients, after which levels gradually declined. 38 patients (38 %) had biopsy-proven rejection within the first year. We did not find evidence of an association between TTV and serum trough levels, events of rejection, nor flow cytometric immunophenotype. We report data on a large cohort of heart transplant patients and contribute to the understanding of how TTV behaves in transplant patients. Despite not finding an association with rejection, our results provide important insights into the kinetics of TTV levels after transplantation, which may be useful in future studies of immune function in heart transplant patients.

Detecting mismatched donor HLA types from allograft biopsies - An easily applicable tool for improved individualized risk assessment.

Short-term allograft survival has improved among solid organ transplant (SOT) patients. An increasing number of SOT patients are prepared for re-transplantation because of chronic allograft failure. Lack of HLA typing or incomplete HLA typing of previous donors complicates pretransplant risk assessment, as repeated HLA mismatches may be missed. In addition, a complete HLA type of the donor is essential in the diagnosis of antibody-mediated rejection. We aimed to determine donor HLA types from allograft biopsies from kidney, heart and liver grafts. Graft biopsies were obtained from 13 kidney, heart and liver transplanted patients. HLA typing was performed using q-PCR. Alleles of both donor and recipient origin were detected, and donor HLA type was concluded by deducting known HLA types of the recipient. For all 13 patients, we were able to determine mismatched donor HLA alleles from graft material. These results are promising, because they enable better individualized risk assessment.

Half body irradiation of patients with multiple bone metastases: a phase II trial.

AIM OF STUDY: The primary aim of this study was to evaluate the effect of half-body irradiation (HBI) on pain and quality of life in cancer patients with multiple bone metastases. The secondary aim was to evaluate side effects of the treatment. PATIENTS AND METHODS: A total of 44 patients received lower (n = 37), upper (n = 5), or sequential HBI (n = 2). The dose for lower HBI was 8 Gy in one fraction and for upper HBI 7 Gy in one fraction, with reduction of the lung dose to 6 Gy in one fraction by partial shielding. The majority of patients (n = 41) were males with prostate cancers (93%). Outcome and side effects were measured by the EORTC Quality of Life Questionnaire C30 (QLQ-C30), and by the doctors' toxicity scores in the medical record. Pain relief was defined as a reduction of more than 10 points on the QLQ-C30 scale. Evaluations were performed before and 2, 4, 8, 16, and 24 weeks after treatment. RESULTS: Relief of pain was observed in 76% of the patients receiving HBI with 8.8% of the patients experiencing complete pain relief with no residual pain in the treated field. For most patients, the pain relief was lasting throughout the follow-up period. About one third of the patients were able to reduce their intake of analgesics. Grade 1-2 diarrhoea was the most common side effect observed in 49% of the patients two weeks after treatment. Mild pulmonary symptoms (grade 1-2) were observed in four of seven patients receiving upper HBI. No clear effect was observed on the patients' global quality of life. CONCLUSION: Single fraction HBI is safe and effective providing long lasting pain reduction in 76% of patients with multiple bone metastases.

Mechanisms of dexamethasone-mediated inhibition of Toll-like receptor signaling induced by Neisseria meningitidis and Streptococcus pneumoniae.

Excessive inflammation contributes to the pathogenesis of bacterial meningitis, which remains a serious disease despite treatment with antibiotics. Therefore, anti-inflammatory drugs have important therapeutic potential, and clinical trials have revealed that early treatment with dexamethasone significantly reduces mortality and morbidity from bacterial meningitis. Here we investigate the molecular mechanisms behind the inhibitory effect of dexamethasone upon the inflammatory responses evoked by Neisseria meningitidis and Streptococcus pneumoniae, two of the major causes of bacterial meningitis. The inflammatory cytokine response was dependent on Toll-like receptor signaling and was strongly inhibited by dexamethasone. Activation of the NF-kappaB pathway was targeted at several levels, including inhibition of IkappaB phosphorylation and NF-kappaB DNA-binding activity as well as upregulation of IkappaB alpha synthesis. Our data also revealed that the timing of steroid treatment relative to infection was important for achieving strong inhibition, particularly in response to S. pneumoniae. Altogether, we describe important targets of dexamethasone in the inflammatory responses evoked by N. meningitidis and S. pneumoniae, which may contribute to our understanding of the clinical effect and the importance of timing with respect to corticosteroid treatment during bacterial meningitis.

Streptococcus pneumoniae stabilizes tumor necrosis factor alpha mRNA through a pathway dependent on p38 MAPK but independent of Toll-like receptors.

BACKGROUND: Streptococcus pneumoniae is a human pathogenic bacteria and a major cause of severe invasive diseases, including pneumonia, bacteremia, and meningitis. Infections with S. pneumoniae evoke a strong inflammatory response, which plays a major role in the pathogenesis of pneumococcal disease. RESULTS: In this study, we have examined how S. pneumoniae affects expression of the inflammatory cytokine tumor necrosis factor (TNF) alpha, and the molecular mechanisms involved. Secretion of TNF-alpha was strongly induced by S. pneumoniae, which was able to stabilize TNF-alpha mRNA through a mechanism dependent on the viability of the bacteria as well as the adenylate uridylate-rich elements in the 3'untranslated region of TNF-alpha mRNA. The ability of S. pneumoniae to stabilize TNF-alpha mRNA was dependent on the mitogen-activated protein kinase (MAPK) p38 whereas inhibition of Toll-like receptor signaling via MyD88 did not affect S. pneumoniae-induced mRNA stabilization. P38 was activated through a pathway involving the upstream kinase transforming growth factor-activated kinase 1 and MAPK kinase 3. CONCLUSION: Thus, S. pneumoniae stabilizes TNF-alpha mRNA through a pathway dependent on p38 but independent of Toll-like receptors. Production of TNF-alpha may contribute significantly to the inflammatory response raised during pneumococcal infection.

Weekly docetaxel with concurrent radiotherapy in locally advanced non-small cell lung cancer: a phase I/II study with 5 years' follow-up.

This Phase I/II study investigated weekly docetaxel (Taxotere) with concurrent radiotherapy in 42 patients with untreated stage III non-small cell lung cancer (NSCLC). All patients were treated with chest irradiation: 2Gy administered 5 days/week for 5 weeks, to a total of 50Gy. Docetaxel (1-h infusion) was administered on days 1, 8, 22, and 29< or =2 h before radiation fractions 1, 6, 16, and 21 (i.e. every week excluding the third week of treatment). In the Phase I study (n=12), docetaxel was started at 20 mg/m2 per week (n=3) and escalated in 10 mg/m2 increments (30 mg/m2, n=3; 40 mg/m2, n=6). Dose-limiting toxicity (grade 3-4 esophagitis) occurred with docetaxel 40 mg/m2. The Phase II study (n=30), therefore, evaluated docetaxel 30 mg/m2 (considered recommended dose). All patients except one experienced asymptomatic grade 3-4 lymphopenia; four patients (9.5%) had grade 3-4 esophagitis. The overall response rate was 45.5%, with eight (24.2%) complete responses. The median time to progression at the recommended dose of 30 mg/m2 (n=33) was 12.0 months and the median survival time was 13.6 months. The 1-year survival rate was 60.6%. Five patients (one from Phase I and four from Phase II) were alive after >5 years. In conclusion, weekly docetaxel 30 mg/m2 plus radiotherapy is active and well tolerated in stage III NSCLC.

T cells detect intracellular DNA but fail to induce type I IFN responses: implications for restriction of HIV replication.

HIV infects key cell types of the immune system, most notably macrophages and CD4+ T cells. Whereas macrophages represent an important viral reservoir, activated CD4+ T cells are the most permissive cell types supporting high levels of viral replication. In recent years, it has been appreciated that the innate immune system plays an important role in controlling HIV replication, e.g. via interferon (IFN)-inducible restriction factors. Moreover, innate immune responses are involved in driving chronic immune activation and the pathogenesis of progressive immunodeficiency. Several pattern recognition receptors detecting HIV have been reported, including Toll-like receptor 7 and Retinoic-inducible gene-I, which detects viral RNA. Here we report that human primary T cells fail to induce strong IFN responses, despite the fact that this cell type does express key molecules involved in DNA signaling pathways. We demonstrate that the DNA sensor IFI16 migrates to sites of foreign DNA localization in the cytoplasm and recruits the signaling molecules stimulator of IFN genes and Tank-binding kinase, but this does not result in expression of IFN and IFN-stimulated genes. Importantly, we show that cytosolic DNA fails to affect HIV replication. However, exogenous treatment of activated T cells with type I IFN has the capacity to induce expression of IFN-stimulated genes and suppress HIV replication. Our data suggest the existence of an impaired DNA signaling machinery in T cells, which may prevent this cell type from activating cell-autonomous anti-HIV responses. This phenomenon could contribute to the high permissiveness of CD4+ T cells for HIV-1.

Genomic HIV RNA induces innate immune responses through RIG-I-dependent sensing of secondary-structured RNA.

BACKGROUND: Innate immune responses have recently been appreciated to play an important role in the pathogenesis of HIV infection. Whereas inadequate innate immune sensing of HIV during acute infection may contribute to failure to control and eradicate infection, persistent inflammatory responses later during infection contribute in driving chronic immune activation and development of immunodeficiency. However, knowledge on specific HIV PAMPs and cellular PRRs responsible for inducing innate immune responses remains sparse. METHODS/PRINCIPAL FINDINGS: Here we demonstrate a major role for RIG-I and the adaptor protein MAVS in induction of innate immune responses to HIV genomic RNA. We found that secondary structured HIV-derived RNAs induced a response similar to genomic RNA. In primary human peripheral blood mononuclear cells and primary human macrophages, HIV RNA induced expression of IFN-stimulated genes, whereas only low levels of type I IFN and tumor necrosis factor α were produced. Furthermore, secondary structured HIV-derived RNA activated pathways to NF-κB, MAP kinases, and IRF3 and co-localized with peroxisomes, suggesting a role for this organelle in RIG-I-mediated innate immune sensing of HIV RNA. CONCLUSIONS/SIGNIFICANCE: These results establish RIG-I as an innate immune sensor of cytosolic HIV genomic RNA with secondary structure, thereby expanding current knowledge on HIV molecules capable of stimulating the innate immune system.

Role of mitogen-activated protein kinases, nuclear factor-kappaB, and interferon regulatory factor 3 in Toll-like receptor 4-mediated activation of HIV long terminal repeat.

Monocytes/macrophages are known to represent a potential reservoir of human immunodeficiency virus type 1 (HIV-1), which ensures continuous replication of the virus in patients on highly active antiretroviral therapy (HAART). Infected macrophages are a highly productive source of HIV-1 during infections with common opportunistic pathogens. Previous studies report that toll like receptors (TLR)s play a role in HIV-1 replication in macrophages. Here, we investigate the three main pathways activated through TLR4 and the interactions with the HIV-1 long terminal repeat (LTR), using human embryonic kidney (HEK) 293 cells expressing TLR4 and transfected with a luciferase reporter under the control of the HIV-1 LTR. Here, we demonstrate, that TLR4-mediated activation of HIV-LTR is largely governed by the nuclear factor-kappaB pathway. Neither of the mitogen-activated protein kinases ERK1/2, JNK, or p38 nor the transcription factor interferon regulatory factor 3 were involved in the direct transactivation of HIV-LTR through stimulation of TLR4.