Molecular cloning and expression of rhesus macaque and sooty mangabey interleukin 16: biologic activity and effect on simian immunodeficiency virus infection and/or replication

The CD8+ T Cell Noncytotoxic Antiviral Responses

The CD8+ T cell noncytotoxic antiviral response (CNAR) was discovered during studies of asymptomatic HIV-infected subjects more than 30 years ago. In contrast to CD8+ T cell cytotoxic lymphocyte (CTL) activity, CNAR suppresses HIV replication without target cell killing. This activity has characteristics of innate immunity: it acts on all retroviruses and thus is neither epitope specific nor HLA restricted. The HIV-associated CNAR does not affect other virus families. It is mediated, at least in part, by a CD8+ T cell antiviral factor (CAF) that blocks HIV transcription. A variety of assays used to measure CNAR/CAF and the effects on other retrovirus infections are described. Notably, CD8+ T cell noncytotoxic antiviral responses have now been observed with other virus families but are mediated by different cytokines. Characterizing the protein structure of CAF has been challenging despite many biologic, immunologic, and molecular studies. It represents a low-abundance protein that may be identified by future next-generation sequencing approaches. Since CNAR/CAF is a natural noncytotoxic activity, it could provide promising strategies for HIV/AIDS therapy, cure, and prevention.

Secretion of antiretroviral chemokines by human cells cultured with acyclic nucleoside phosphonates

Acyclic nucleoside phosphonates are novel class of clinically broadly used antivirotics effective against replication of both DNA viruses and retroviruses including human immunodeficiency virus (HIV). We have investigated their in vitro effects on immune defence mechanisms in human peripheral blood mononuclear cells, with the main emphasis on expression of cytokines which are able to suppress the entry of HIV in cells. Included in the study were prototype acyclic nucleoside phosphonates, i.e. 9-[2-(phosphonomethoxy)ethyl]adenine (PMEA; adefovir), 9-[2-(phosphonomethoxy)ethyl]-2,6-diaminopurine (PMEDAP), (R)-and (S)-enantiomers of 9-[2-(phosphonomethoxy)propyl]adenine [(R)-PMPA; tenofovir] and [(S)-PMPA], and of 9-[2-(phosphonomethoxy)propyl]-2,6-diaminopurine [(R)-PMPDAP] and [(S)-PMPDAP], and their N(6)-substituted derivatives. Some of the compounds were found to substantially enhance secretion of chemokines such as macrophage inflammatory protein-1alpha (MIP-alpha/CCL3), and "regulated on activation of normal T cell expressed and secreted" (RANTES/CCL5). Secretion of MIP-1beta/CCL4 was only marginally increased, whereas production of interleukin-16 (IL-16) and interferon-gamma (IFN-gamma) remained uninfluenced. The most effective proved to be the N(6)-cyclooctyl-PMEDAP, N(6)-isobutyl-PMEDAP, N(6)-pyrrolidino-PMEDAP, N(6)-cyclopropyl-(R)-PMPDAP, and N(6)-cyclopentyl-(R)-PMPDAP derivatives. Remarkably enhanced secretion of chemokines was reached within 2-4 h of the cell culture, and was observed at concentration of 2-5 microM. It may be suggested that acyclic nucleoside phosphonates represent a new generation of antivirotics with combined antimetabolic and therapeutically prospective immunostimulatory properties.

Interleukin-12 and interleukin-16 in periodontal disease

The immune system plays an important role in the pathological process of periodontitis. Interleukin-12 (IL-12) is produced by monocytes, macrophages and neutrophils. These cells are proinflammatory infiltrates in periodontitis tissues. High IL-12 will contribute to the immune reaction to Th1 type. IL-12 is an inducer of INF-r production. IFN-gamma itself can also activate IL-12 production. Lipopolysaccharides (LPS) of periodontopathogens are also activators of IL-12. Interleukin-16 (IL-16) can cause the high affinity of IL-2 receptors on CD4+ cells and is chemotaxis to Th1 cells and CD4+ T cells. IL-16 can stimulate monocytes to produce proinflammatory cytokines and is highly associated with inflammation including arthritis, enteritis and allergic rhinitis. However, the information on IL-12 and IL-16 in periodontitis is not clear. In this study, 105 GCF samples were collected from 19 periodontal disease patients and 6 healthy ones. The clinical periodontal indices, the habits of cigarette smoking and alcohol drinking were recorded. ELISA was used to determine the levels of IL-12 and IL16 in the GCF. In the non-smoking/non-alcohol-drinking individuals: (1) the total amount of IL-12 (but not IL-16) was significantly higher in chronic periodontitis (CP) sites than gingivitis (G) or healthy (H) sites; (2) the diseased sites (CP + G) had a significantly higher total amount of IL-12 (but not IL-16) than the H sites. Among CP sites, both the concentration and total amount of IL-16 (but not IL-12) were significantly higher in alcohol drinkers/cigarette smokers as compared to the non-drinkers/non-smokers. CP sites of the drinkers/smokers also had significantly deeper probing pocket depth than sites of those without these two habits. IL-12 and IL-16 may be related to the pathogenesis of periodontal disease, but within the periodontitis sites, IL-16 may be related to disease severity in alcohol drinkers/smokers.

Use of recombinant cytokines for optimized induction of antiviral immunity against SIV in the nonhuman primate model of human AIDS

Outbreaks of infectious diseases such as HIV and the much televised and attention-getting outbreaks of diseases such as Ebola, Hantaviruses, and the most recent outbreak of SARS have induced a significant new interest in the formulations and more importantly the science of vaccinology, which has previously to a large extent been conducted empirically. Our laboratory has focused on the use of recombinant nonhuman primate cytokines as adjunctive therapies for inducing antigen-specific immune responses in monkeys because most recombinant human cytokines appear to be immunogenic. This article provides a summary of our work with such cytokines, which includes attempts to define optimum dosing schedules that lead to optimal primary and lasting memory antigen-specific immune responses.

Prospects for IL-16 in the treatment of AIDS

IL-16 is a multi-functional cytokine that uses CD4 as a receptor to signal diverse biological activities by target cells including T-lymphocytes, monocytes and eosinophils. IL-16 has been shown to repress HIV-1 infection in lymphocytes and monocytic cells and it is active against both laboratory and naturally acquired virus isolates. In lymphocytes, the repressive effect of IL-16 occurs at the level of virus transcription, while it appears to inhibit viral entry in monocytic cells. Clinical studies comparing serum IL-16 levels with the state of HIV-1 disease suggest that this cytokine is a functionally significant endogenous antiviral factor. The antiviral activity of IL-16 may be of therapeutic benefit in HIV/AIDS but its greatest potential is for immune reconstitution. Stimulation of CD4+ T-cells with IL-16 primes cells to respond to IL-2, by upregulating the expression of IL-2 receptor p75 (CD25). Co-treatment of peripheral blood mononuclear cells (PBMC) with IL-16 plus IL-2 (or IL-15) in vitro selectively expands the population of CD4+ T-cells. Clinical trials of recombinant IL-2 have already shown promise in HIV/AIDS. In combination with IL-16, the beneficial effects of IL-2 may be augmented and specifically targeted to CD4+ T-cells. Thus, IL-16 shows considerable promise as an agent for the biological therapy of HIV/AIDS.

Immunization of cats against feline immunodeficiency virus (FIV) infection by using minimalistic immunogenic defined gene expression vector vaccines expressing FIV gp140 alone or with feline interleukin-12 (IL-12), IL-16, or a CpG motif

Four groups of cats, each containing four animals, were immunized at 0, 3, and 6 weeks with minimalistic immunogenic defined gene expression vector (MIDGE) vaccines containing the gene(s) for feline immunodeficiency virus (FIV) gp140, FIV gp140 and feline interleukin-12 (IL-12), FIV gp140 and feline IL-16, or FIV gp140 and a CpG motif. MIDGEs were coated onto gold beads and injected intradermally with a gene gun. A fifth group of four cats were immunized in an identical manner but with blank gold beads. All cats were challenge exposed to virulent FIV 4 weeks following the final immunization, and the course of infection was monitored. The two groups of cats immunized with the FIV gp140 gene alone or with blank gold particles became highly viremic and seroconverted as early as 4 weeks after infection. In contrast, three of four cats immunized with FIV gp140 in combination with feline IL-12 failed to become viremic or seropositive, as has been shown elsewhere (F. S. Boretti, C. M. Leutenegger, C. Mislin, et al., AIDS 14:1749-1757, 2000). Here we show the effect of IL-12 when used as an adjuvant on the viral RNA and DNA load and on the cytokine profile. In addition, the two groups of cats immunized either with gp140 and IL-16 or with gp140 and the CpG had greatly reduced viremia. Protection correlated weakly with cytotoxic T-lymphocyte activity and increased cytokine transcription of IL-12, gamma interferon, and IL-10 by peripheral blood mononuclear cells in the postchallenge period. This study extends the data on IL-12 and provides new results on CpG motifs and IL-16 used as adjuvants in the FIV cat model.

Molecular characterization of feline interleukin 16: chemotactic activity and effect on feline immunodeficiency virus infection and/or replication

Interleukin 16 (IL-16) has been shown to diminish HIV and SIV replication through inhibition of HIV and SIV mRNA transcription. To evaluate its role in the FIV cat model, we cloned and expressed feline IL-16 and determined its ability to induce chemotaxis as well as to inhibit FIV replication in cultured PBMCs. Sequence comparison of rfIL-16 with human, African green monkey, rhesus macaque, and mouse IL-16 showed 84.2, 84.5, 84.4, and 79.4% identity at the nucleotide sequence level and 93, 91.5, 90.7, and 87.2% identity at the amino acid sequence level, respectively. Biocharacterization of rfIL-16 revealed potent induction of chemotaxis (p < 0.05). In addition, p24 production from feline PBMCs infected with FIV Zurich 2 in vitro was decreased up to 87% (p < 0.05). These data demonstrate biologic and antiviral functionality of rfIL-16.

Recombinant human CD40 ligand inhibits simian immunodeficiency virus replication: a role for interleukin- 16

CD40 ligand (CD40L), expressed on activated T cells, binds its receptor, CD40, on dendritic cells, B cells, and monocytes/ macrophages. Human immunodeficiency virus (HIV)-infected individuals exhibit normal B-cell CD40 expression but diminished expression of CD40L on CD4 + T cells. Thus, we studied recombinant human CD40L (huCD40L) in an in vitro rhesus macaque model of acquired immunodeficiency syndrome (AIDS). huCD40L induced peripheral blood mononuclear cell (PBMC) proliferation independent of mitogenic cytokines and led to a 70% reduction in p27 production by simian immunodeficiency virus (SIV) mac239 infected PBMCs (P < 0.05). Reverse transcriptase-polymerase chain reaction (RT-PCR) analysis showed reduced expression of SIV gag and increased expression of interleukin (IL)-16 mRNA. Supernatants from huCD40L-stimulated PBMC and control cultures contained similar amounts of IL-16, suggesting an intracellular antiviral effect by IL-16. Phytohemagglutinin (PHA)-stimulated PBMCs similarly cultured with huCD40L showed only slight increases in chemokine production (P > 0.05). These results suggest that huCD40L inhibits replication (antigen and mRNA production) of SIVmac239. This response involves huCD40L induction of IL16 mRNA expression and appears to be independent of beta-chemokines.

Inhibition of Tyrosine Kinase Activation Blocks the Down-Regulation of CXC Chemokine Receptor 4 by HIV-1 gp120 in CD4+ T Cells

Because the binding of HIV-1 envelope to CD4 initiates a configurational change in glycoprotein 120 (gp120), enabling it to interact with fusion coreceptors, we investigated how this process interferes with the expression and function of CXC chemokine receptor 4 (CXCR4) in CD4+ T lymphocytes. A recombinant gp120 (MN), after preincubation with CD4+ T lymphocytes, significantly inhibited the binding and chemotaxis of the cells in response to the CXCR4 ligand stromal cell-derived factor-1α (SDF-1α), accompanied by a markedly reduced surface expression of CXCR4. gp120, but not SDF-1α, induced rapid tyrosine phosphorylation of src-like kinase p56lck in CD4+ T cells, whereas both gp120 and SDF-1α caused phosphorylation of the CXCR4. The tyrosine kinase inhibitor herbimycin A abolished the phosphorylation of p56lck and CXCR4 induced by gp120 in association with maintenance of normal expression of cell surface CXCR4 and a migratory response to SDF-1α. Thus, a CD4-associated signaling molecule(s) including p56lck is activated by gp120 and is required for the down-regulation of CXCR4.