Immunogenic and tolerogenic signatures in human immunodeficiency virus (HIV)-infected controllers compared with progressors and a conversion strategy of virus control.

Epidemiological studies have identified a small cohort of controllers of human immunodeficiency virus (HIV)-1 infection, who without treatment have no detectable virus, and others who progress at a variable rate. The objective of this study was to distinguish immune signatures in HIV controllers and progressors, by evaluating tolerogenic and immunogenic factors in untreated HIV-1 infected individuals. The recruited population was divided into putative elite controllers (PEC), long-term non-progressors (LTNP), normal progressors (NP) and fast progressors (FP). The proportion of regulatory T cells [T(regs) , CD4+ CD25+ forkhead box P3 (FoxP3+)], programmed death (PD)-1 and cytotoxic T lymphocyte antigen (CTLA)-inhibitory molecules and CD40L, CD69 and Ki67 activation markers were evaluated in peripheral blood mononuclear cells (PBMC) by flow cytometry. Significant differences were found between HIV controllers and HIV progressors, with up-regulation of T(regs) , PD-1 and CTLA-4 and decrease of CD40L expression in progressors compared with controllers. Expression of CD40L and concentrations of interleukin (IL)-6, CCL-3, and CCL-4 were significantly higher in PEC and LTNP than in NP and FP. In an attempt to convert immune signatures of progressors to those of controllers, seven agents were used to stimulate PBMC from the four cohorts. Treatment with CD40L and IL-4 or PD-1 antibodies in vitro were most effective in converting the immune signatures of progressors to those observed in controllers by down-regulating T(regs) and up-regulating CD40L expression in CD4+ T cells. The conversion concept merits translation to in vivo immune control of HIV infection.

Innate immunity and HIV-1 infection.

HIV-1 is predominantly transmitted through mucosal tissues, targeting CD4(+)CCR5(+) T cells, 50% of which are destroyed within 2 weeks of infection. Conventional vaccination strategies have so far failed to prevent HIV-1 infection. Neither antibodies nor cytotoxic lymphocytes are capable of mounting a sufficiently rapid immune response to prevent early destruction of these cells. However, innate immunity is an early-response system, largely independent of prior encounter with a pathogen. Innate immunity can be classified into cellular, extracellular, and intracellular components, each of which is exemplified in this review by γδ T cells, CC chemokines, and APOBEC3G, respectively. First, γδ T cells are found predominantly in mucosal tissues and produce cytokines, CC chemokines, and antiviral factors. Second, the CC chemokines CCL-3, CCL-4, and CCL-5 can be upregulated by immunization of macaques with SIVgp120 and gag p27, and these can bind and downmodulate CCR5, thereby inhibiting HIV-1 entry into the host cells. Third, APOBEC3G is generated and maintained following rectal mucosal immunization in rhesus macaques for over 17 weeks, and the innate anti-SIV factor is generated by CD4(+)CD95(+)CCR7(-) effector memory T cells. Thus, innate anti-HIV-1 or SIV immunity can be linked with immune memory, mediated by CD4(+) T cells generating APOBEC3G. The multiple innate functions may mount an early anti-HIV-1 response and either prevent viral transmission or contain the virus until an effective adaptive immune response develops.

The emerging role of innate immunity in protection against HIV-1 infection.

Preventive immunization against HIV-1 infection requires a rapid immune response that does not rely exclusively on B or T cell memory. Innate immunity may fulfill this function as it may be activated directly at the time of HIV-1 transmission, inhibit early HIV-1 replication, stimulate adaptive immunity and enable specific antibodies followed by CD8(+) T cells to deal with the virus effectively. The three components of innate immunity - cellular, extracellular and intracellular - are presented, with an example given for each of these components; gammadelta T cells, CC chemokines and APOBEC3G. This brief account is presented to highlight the immuno-virological concept of coordinating activated innate immunity with adaptive antibody and T cell responses in preventive vaccination against HIV-1 infection.

Tumour necrosis factor-alpha production stimulated by heat shock protein 70 and its inhibition in circulating dendritic cells and cells eluted from mucosal tissues in Crohn's disease.

Summaryand interleukin (IL)-12 by dendritic cells (DC) from patients with Crohn's disease. TNF-alpha concentration was increased significantly when DC from Crohn's disease were stimulated with HSP70 or CD40L and this was associated with signalling by the extracellular signal regulated kinase (ERK) 1/2 and p38 mitogen activated protein (MAP) kinase pathway. IL-12 production was also increased when DC were stimulated with HSP70. Cells eluted from inflamed intestinal mucosa from Crohn's disease, stimulated with HSP70, CD40L or lipopolysaccharide produced significantly greater TNF-alpha and IL-12 concentrations than cells from uninflamed mucosa. Significant inhibition of TNF-alpha production was demonstrated when DC from peripheral blood mononuclear cells or cells eluted from intestinal mucosa of Crohn's disease were treated with either the HSP70 inhibitory peptide (aa 457-496) or peptides derived from CD40 and CD40L. These inhibitory peptides target the CD40-CD40L and the emerging CD40-HSP70 co-stimulatory pathway. Our findings offer a novel strategy to prevent excessive production of TNF-alpha in Crohn's disease.

Functional domains of HSP70 stimulate generation of cytokines and chemokines, maturation of dendritic cells and adjuvanticity.

Microbial HSP70 (heat-shock protein 70) consists of three functionally distinct domains: an N-terminal 44 kDa ATPase portion (amino acids 1-358), followed by an 18 kDa peptide-binding domain (amino acids 359-494) and a C-terminal 10 kDa fragment (amino acids 495-609). Immunological functions of these three different domains in stimulating monocytes and dendritic cells have not been fully defined. However, the C-terminal portion (amino acids 359-610) stimulates the production of CC chemokines, IL-12 (interleukin-12), TNFalpha(tumour necrosis factor alpha), NO and maturation of dendritic cells and also functions as an adjuvant in the induction of immune responses. In contrast, the ATPase domain of microbial HSP70 mostly lacks these functions. Since the receptor for HSP70 is CD40, which with its CD40 ligand constitutes a major co-stimulatory pathway in the interaction between antigen-presenting cells and T-cells, HSP70 may function as an alternative ligand to CD40L. HSP70-CD40 interaction has been demonstrated in non-human primates to play a role in HIV infection, in protection against Mycobacterium tuberculosis and in conversion of tolerance to immunity.

Oral tolerization with peptide 336-351 linked to cholera toxin B subunit in preventing relapses of uveitis in Behcet's disease.

Behcet's disease (BD) specific peptide (p336-351) was identified within the human 60 kD heat shock protein (HSP60). Oral p336-351 induced uveitis in rats which was prevented by oral tolerization with the peptide linked to recombinant cholera toxin B subunit (CTB). This strategy was adopted in a phase I/II clinical trial by oral administration of p336-351-CTB, 3 times weekly, followed by gradual withdrawal of all immunosuppressive drugs used to control the disease in 8 patients with BD. The patients were monitored by clinical and ophthalmological examination, as well as extensive immunological investigations. Oral administration of p336-351-CTB had no adverse effect and withdrawal of the immunosuppressive drugs showed no relapse of uveitis in 5 of 8 patients or 5 of 6 selected patients who were free of disease activity prior to initiating the tolerization regimen. After tolerization was discontinued, 3 of 5 patients remained free of relapsing uveitis for 10-18 months after cessation of all treatment. Control of uveitis and extra-ocular manifestations of BD was associated with a lack of peptide-specific CD4+ T cell proliferation, a decrease in expression of TH1 type cells (CCR5, CXCR3), IFN-gamma and TNF-alpha production, CCR7+ T cells and costimulatory molecules (CD40 and CD28), as compared with an increase in these parameters in patients in whom uveitis had relapsed. The efficacy of oral peptide-CTB tolerization will need to be confirmed in a phase III trial, but this novel strategy in humans might be applicable generally to autoimmune diseases in which specific antigens have been identified.

Immunogenicity of the extracellular domains of C-C chemokine receptor 5 and the in vitro effects on simian immunodeficiency virus or HIV infectivity.

The C-C chemokine receptor CCR5 serves an important function in chemotaxis of lymphocytes, monocytes, and dendritic cells. CCR5 is also the major coreceptor in most macrophage-tropic HIV-1 infections. Immunization of rhesus macaques with a baculovirus-generated CCR5 construct or peptides derived from the sequences of the four extracellular domains of CCR5 elicited IgG and IgA Abs, inhibition of SIV replication, and CD4+ T cell proliferative responses to three of the extracellular domains of CCR5. The immune sera reacted with cell surface CCR5 expressed on HEK 293 cells. T and B cell epitope mapping revealed major and minor T and B cell epitopes in the N-terminal, first, and second loops of CCR5. The three C-C chemokines, RANTES, macrophage-inflammatory protein-1alpha, and macrophage-inflammatory protein-1beta, were up-regulated by immunization with the CCR5-derived peptides, and the cell surface expression of CCR5 was decreased. The CCR5 Abs were complementary to the C-C chemokines in inhibiting HIV replication in vitro. Immunization with the four extracellular domains of CCR5 suggests that three of them are immunogenic, with maximal T cell responses being elicited by the second loop peptide. However, maximal Abs to the cell surface CCR5 or viral inhibitory Abs in vitro were induced by the N-terminal peptide. Up-regulation of the three C-C chemokines and down-modulation of cell surface CCR5 were elicited by the second loop, N-terminal, and first loop peptides. The data suggest that a dual mechanism of C-C chemokines and specific Abs may engage and down-modulate the CCR5 coreceptors and prevent in vitro HIV or SIV replication.

CD40 is a cellular receptor mediating mycobacterial heat shock protein 70 stimulation of CC-chemokines.

The 70 kDa mycobacterial heat shock protein (Mtb HSP70) stimulates mononuclear cells to release CC-chemokines. We now show that this function of Mtb HSP70, but not human HSP70, is dependent on the cell surface expression of CD40. Deletion of the CD40 cytoplasmic tail abolished, and CD40 antibody inhibited, Mtb HSP70 stimulation of CC-chemokine release. Mtb HSP70 stimulated THP1, KG1 cells, and monocyte-derived dendritic cells to produce RANTES. Specific binding of CD40-transfected HEK 293 cells to Mtb HSP70 was demonstrated by surface plasmon resonance. Coimmunoprecipitation of Mtb HSP70 with CD40 indicates a physical association between these molecules. The results suggest that CD40 is critical in microbial HSP70 binding and stimulation of RANTES production.

Overview of the Second International Workshop to define swine cluster of differentiation (CD) antigens.

The aim of the Second International Swine Cluster of Differentiation (CD) Workshop, supported by the Veterinary Immunology Committee (VIC) of the International Union of Immunological Societies (IUIS), was to standardize the assignment of monoclonal antibodies (mAb) reactive with porcine leukocyte differentiation antigens and to define new antibody clusters. At the summary meeting of the workshop in July, 1995, revisions in the existing nomenclature for Swine CD were approved, so that the rules are now in accord with those for human and ruminant CD. Swine CD numbers will now be given to clusters of mAb to swine orthologues of human CD molecules when homology is proven by (1) suitable tissue distribution and lymphoid cell subset expression, (2) appropriate molecular mass of the antigen recognized by the mAbs, and (3) reactivity of mAbs with the cloned swine gene products, or cross-reactivity of the mAb on the human gene products. In some cases, this reactivity would not be fully proven, mainly due to the lack of cloned gene products; for these CD antigens, the respective clusters will be assigned by the prefix 'w' which will lead to 'wCD' antigens. As a result of the Second International Swine CD Workshop the assignment of 16 mAb to existing CD groups (CD2a, CD4a, CD5a, wCD6, wCD8, CD14, CD18a, wCD21, wCD25) was confirmed, and 2 mAb to existing swine workshop clusters (SWC). More importantly, for the work on the porcine immune system, was the definition of 5 new swine CD antigens, namely CD3 (recognized by 6 new mAb and 3 epitopes), CD16 (1 new mAb), wCD29 (2 mAb), CD45RA (3 mAb) and CD45RC (1 new mAb). Finally, the demarcation of two new SWC molecules in swine, SWC8 (2 mAb) and SWC9 (2 mAb) was confirmed.