Interleukin-37 Expression Is Increased in Chronic HIV-1-Infected Individuals and Is Associated with Inflammation and the Size of the Total Viral Reservoir.

Interleukin-37 (IL-37) is a recently identified cytokine with potent antiinflammatory and immunosuppressive functions. The objective of this study was to compare levels of IL-37 mRNA in immunological subgroups of chronic human immunodeficiency virus-1 (HIV-1)-infected individuals and noninfected controls, to determine IL-37's association with biomarkers of inflammation and reservoir size. This was a cross-sectional study. The HIV-1-infected patients were categorized in three subgroups depending on their combination antiretroviral therapy (cART) treatment status and CD4(+) T-cell count. Quantitative RT-PCR was used for the detection of IL-37 mRNA and HIV-1 DNA in peripheral blood mononuclear cells (PBMCs). Biomarkers in plasma were quantified by enzyme-linked immunosorbent assay (ELISA), whereas T-cell activation was determined by flow cytometry. Lastly, lipopolysaccharide (LPS) stimulations of patients PBMCs were carried out to determine differences in IL-37 mRNA response between the subgroups. Sixty HIV-1-infected patients and 20 noninfected controls were included in the study. Steady-state IL-37 mRNA levels in PBMCs were significantly higher in HIV-1-infected individuals compared with noninfected controls: 2.4-fold (p ≤ 0.01) cART-naïve subjects; 3.9-fold (p ≤ 0.0001) inadequate immunological responders; and 4.0-fold (p ≤ 0.0001) in immunological responders compared with non-infected controls. Additionally, levels of the monocyte inflammatory marker sCD14 correlated with IL-37 mRNA (p = 0.03), whereas there was no association with T-cell activation. Finally, we observed a significant correlation between total viral HIV-1 DNA and IL-37 mRNA in PBMCs (p < 0.0001). Collectively, our data shows that the level of IL-37 mRNA is affected by chronic HIV-1-infection. A relationship with the activation of the monocyte compartment is suggested by the correlation with sCD14 and, interestingly, IL-37 could be related to the size of the total viral HIV-1 reservoir.

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.

HSV-1-induced chemokine expression via IFI16-dependent and IFI16-independent pathways in human monocyte-derived macrophages.

BACKGROUND: Innate recognition is essential in the antiviral response against infection by herpes simplex virus (HSV). Chemokines are important for control of HSV via recruitment of natural killer cells, T lymphocytes, and antigen-presenting cells. We previously found that early HSV-1-mediated chemokine responses are not dependent on TLR2 and TLR9 in human macrophages. Here, we investigated the role of the recently identified innate IFN-inducible DNA receptor IFI16 during HSV-1 infection in human macrophages. METHODS: Peripheral blood mononuclear cells were purified from buffy coats and monocytes were differentiated to macrophages. Macrophages infected with HSV-1 were analyzed using siRNA-mediated knock-down of IFI16 by real-time PCR, ELISA, and Western blotting. RESULTS: We determined that both CXCL10 and CCL3 are induced independent of HSV-1 replication. IFI16 mediates CCL3 mRNA accumulation during early HSV-1 infection. In contrast, CXCL10 was induced independently of IFI16. CONCLUSIONS: Our data provide the first evidence of HSV-1-induced innate immune responses via IFI16 in human primary macrophages. In addition, the data suggest that at least one additional unidentified receptor or innate sensing mechanism is involved in recognizing HSV-1 prior to viral replication.

Timing of Toll-like receptor 9 agonist administration in pneumococcal vaccination impacts both humoral and cellular immune responses as well as nasopharyngeal colonization in mice.

Synthetic oligodeoxynucleotides (ODN) containing unmethylated CpG motifs, CpG ODN, are Toll-like receptor 9 agonists (TLR9a), which have been used as adjuvants in pneumococcal vaccines to improve antibody responses in immunodeficient patients. Here, we examined whether the coadministration of TLR9a with pneumococcal CRM(197)-conjugate vaccine enhances protection against pneumococcal colonization, the levels of antipolysaccharide antibodies, and the CD4(+) T-cell responses. Wild-type BALB/c mice and B-cell-deficient BALB/c Igh-J(tm1Dhu) mice were immunized twice with the following: (i) PCV alone; (ii) simultaneous PCV and TLR9a; (iii) PCV and then TLR9a, after a 48-h delay; (iv) TLR9a alone; and (v) phosphate-buffered saline. Nasopharyngeal protection, serum antibodies, CD4(+) T-cell responses, and clearance of bacteremia after intraperitoneal challenge with Streptococcus pneumoniae 6B were evaluated. We found decreased nasopharyngeal protection against S. pneumoniae 6B colonization after simultaneous immunization with PCV and TLR9a compared to immunization with PCV alone in wild-type BALB/c mice (P = 0.037). A similar trend was observed in B-cell-deficient BALB/c Igh-J(tm1Dhu) mice. Simultaneous administration did not enhance antibody levels and lowered the CRM(197)-specific cytokine release of gamma interferon, interleukin-2 (IL-2), IL-5 and IL-13. Immunization with PCV and then TLR9a, after a 48-h delay, significantly improved nasopharyngeal protection compared to simultaneous administration (P = 0.011). Furthermore, delaying TLR9a delivery increased antibody titers compared to both simultaneous administration (P = 0.001) and PCV immunization alone (P = 0.026). In conclusion, the immunological and clinical impact of adjuvanting a pneumococcal conjugate vaccine (Prevnar; Pfizer) with a TLR9a is highly depended on timing of the adjuvant administration. Thus, careful timing of adjuvant administration may improve novel vaccine formulations.

Peptide Inhibition of Topoisomerase IB from Plasmodium falciparum.

Control of diseases inflicted by protozoan parasites such as Leishmania, Trypanosoma, and Plasmodium, which pose a serious threat to human health worldwide, depends on a rather small number of antiparasite drugs, of which many are toxic and/or inefficient. Moreover, the increasing occurrence of drug-resistant parasites emphasizes the need for new and effective antiprotozoan drugs. In the current study, we describe a synthetic peptide, WRWYCRCK, with inhibitory effect on the essential enzyme topoisomerase I from the malaria-causing parasite Plasmodium falciparum. The peptide inhibits specifically the transition from noncovalent to covalent DNA binding of P. falciparum topoisomerase I, while it does not affect the ligation step of catalysis. A mechanistic explanation for this inhibition is provided by molecular docking analyses. Taken together the presented results suggest that synthetic peptides may represent a new class of potential antiprotozoan drugs.