Mauricio A. Arias

Glucopyranosyl Lipid Adjuvant (GLA), a Synthetic TLR4 Agonist, Promotes Potent Systemic and Mucosal Responses to Intranasal Immunization with HIVgp140

Successful vaccine development against HIV will likely require the induction of strong, long-lasting humoral and cellular immune responses in both the systemic and mucosal compartments. Based on the known immunological linkage between the upper-respiratory and urogenital tracts, we explored the potential of nasal adjuvants to boost immunization for the induction of vaginal and systemic immune responses to gp140. Mice were immunized intranasally with HIV gp140 together with micellar and emulsion formulations of a synthetic TLR4 agonist, Glucopyranosyl Lipid Adjuvant (GLA) and responses were compared to R848, a TLR7/8 agonist, or chitosan, a non TLR adjuvant. GLA and chitosan but not R848 greatly enhanced serum immunoglobulin levels when compared to antigen alone. Both GLA and chitosan induced high IgG and IgA titers in nasal and vaginal lavage and feces. The high IgA and IgG titers in vaginal lavage were associated with high numbers of gp140-specific antibody secreting cells in the genital tract. Whilst both GLA and chitosan induced T cell responses to immunization, GLA induced a stronger Th17 response and chitosan induced a more Th2 skewed response. Our results show that GLA is a highly potent intranasal adjuvant greatly enhancing humoral and cellular immune responses, both systemically and mucosally.

Inhibition of Virulent Mycobacterium tuberculosis by Bcgr and Bcgs Macrophages Correlates with Nitric Oxide Production

The Nramp1 gene controls macrophage resistance or susceptibility to several intracellular microorganisms; however, there is conflicting evidence regarding its role during infection with virulent Mycobacterium tuberculosis. Nitric oxide (NO) is a potent antimycobacterial agent produced by macrophages, which is also regulated by Nramp1. The in vitro ability of B10R (resistant) and B10S (susceptible) murine macrophages to inhibit M. tuberculosis H37Rv and to produce NO in response to infection and interferon-gamma (IFN-gamma) was compared. Infected B10R macrophages inhibited [3H]uracil incorporation by M. tuberculosis and produced higher amounts of NO than did B10S macrophages. IFN-gamma increased the inhibitory activity of both cells. Inhibition of M. tuberculosis by IFN-gamma-activated B10R macrophages was reversed by N(G)-monomethyl-L-arginine (N(G)MMA). L-arginine restored NO production and increased the antimycobacterial activity by IFN-gamma-stimulated N(G)MMA-treated macrophages. The Bcg/Nramp1 gene may regulate macrophage resistance or susceptibility to virulent M. tuberculosis by a differential capability of these cells to produce NO.

Variants of the Human NRAMP1 Gene and Altered Human Immunodeficiency Virus Infection Susceptibility

In a population-based case-control study, 182 human immunodeficiency virus (HIV)-positive persons and 135 healthy control subjects were enrolled from the metropolitan area of Medellin, Colombia. Four genotypes of the natural resistance-associated macrophage protein l (NRAMP1) gene (5 GT repeat, 274C/T, 469+14G/T, and 823C/T) were associated with altered risk of HIV infection (P=.013,.015,.020, and. 035, respectively). Three of these markers (5 [GT]n, 274C/T, 469+14G/T) are in strong linkage disequilibrium, and genotypes of these markers are associated with reduced risk of HIV infection with relative risks (RRs) of 0.35 (95% confidence interval [CI], 0.14-0.91), 0.31 (CI, 0.10-0.93), and 0.24 (CI, 0.08-0.72), respectively. Conversely, heterozygosity at the fourth independent marker (823C/T) was associated with increased risk of HIV infection (RR, 2.29; CI, 1.06-4.92). These findings suggest that NRAMP1 modifies risk of HIV infection.

TNF-α in Tuberculosis: A Cytokine with a Split Personality

TNF-alpha is an essential component of the innate defence mechanism of the host against pathogenic challenge. Unfortunately, it can also play a major role in the pathology of certain diseases, such as tuberculosis. This disease is a striking example of the role of TNF-alpha as a double-edged sword, because apart from its role in controlling the Mycobacterium tuberculosis infection, it can also cause severe tissue damage. TNF-alpha exhibits a very complex network of interactions and many of its activities are still not fully understood. This report aims to review the pivotal role of TNF-alpha in controlling the mycobacterial infection, with a particular emphasis on its influence on chemokine expression and cell movement during granuloma formation, and the issues surrounding the use of TNF-alpha inhibitors for therapeutic use in inflammatory diseases.

Targeting of HIV-p24 particle-based vaccine into differential skin layers induces distinct arms of the immune responses

Skin routes of immunization such as subcutaneous (SC), intradermal (ID) and transcutaneous (TC) administration are utilized for vaccination against various pathogens, without understanding their potential impact on the outcome of immune responses. We demonstrated that SC immunization induced HIV-1 p24 specific IgG in absence of antigen-specific CD8 T cells, whereas the ID route induced both cellular and humoral responses. Interestingly, TC application through empty hair follicular ducts, targeting epidermal Langerhans Cells (LCs), induced major CD8 effector cells, in the absence of IgG. However, high levels of mucosal IgA, were localized in the stratified epithelium of the vagina after TC prime. We propose that re-directing the immune responses by targeting differential skin immunization routes, offers enormous potential for innovative vaccination strategies, especially against HIV.

Absence of association between mannose-binding lectin gene polymorphisms and HIV-1 infection in a Colombian population

Mannose-binding lectin (MBL) is a calcium-dependent lectin shown to play an important role in innate immunity to infection by activating the classical complement pathway and phagocytosis. In vitro studies have shown that MBL is able to bind to the gp120 HIV-1 surface antigen, and variants of the gene are associated with increased risk of HIV infection among Scandinavians. We investigated the association of genetic MBL variants and HIV-1 infection in 278 Colombian HIV-infected and control individuals. MBL genotype frequencies were similar for both groups, and no association was detected between MBL alleles B, C, and D and susceptibility to HIV-1 infection (P=1.0). Since there is a well-documented link between the tested MBL alleles and very low MBL serum concentration, these results do not support the hypothesis that MBL levels are a risk factor for HIV-1 infection in Colombia.

CD14 gene promoter polymorphism in different clinical forms of tuberculosis

Mycobacterium tuberculosis interacts with monocyte-macrophages through cell surface molecules including CD14. A soluble form of CD14 (sCD14) exists in human serum, and higher amounts of it are found in tuberculosis. A polymorphism on CD14 gene promoter was associated with increased sCD14 levels in some diseases. To evaluate whether this polymorphism associates with tuberculosis, its clinical forms, and increased sCD14, genotype/allele frequencies in tuberculosis patients were compared with the controls. Results confirmed increased levels of sCD14 in patients with tuberculosis, and those with miliary tuberculosis had the highest levels. sCD14 decreased to normal levels after anti-tuberculosis treatment. No association was found between the CD14 polymorphism and tuberculosis or sCD14 levels. Results suggest that sCD14 may be involved in anti-tuberculosis immune response, but its increase is a consequence of infection rather than a predisposed genetic trait. Measuring sCD14 in tuberculosis may help monitor anti-tuberculosis treatment.

Carnauba wax nanoparticles enhance strong systemic and mucosal cellular and humoral immune responses to HIV-gp140 antigen.

Induction of humoral responses to HIV at mucosal compartments without inflammation is important for vaccine design. We developed charged wax nanoparticles that efficiently adsorb protein antigens and are internalized by DC in the absence of inflammation. HIV-gp140-adsorbed nanoparticles induced stronger in vitro T-cell proliferation responses than antigen alone. Such responses were greatly enhanced when antigen was co-adsorbed with TLR ligands. Immunogenicity studies in mice showed that intradermal vaccination with HIV-gp140 antigen-adsorbed nanoparticles induced high levels of specific IgG. Importantly, intranasal immunization with HIV-gp140-adsorbed nanoparticles greatly enhanced serum and vaginal IgG and IgA responses. Our results show that HIV-gp140-carrying wax nanoparticles can induce strong cellular/humoral immune responses without inflammation and may be of potential use as effective mucosal adjuvants for HIV vaccine candidates.

Thymic stromal lymphopoietin (TSLP) acts as a potent mucosal adjuvant for HIV-1 gp140 vaccination in mice

The development of a successful vaccine against HIV is likely to require the induction of strong and long‐lasting humoral immune responses at the mucosal portal of virus entry. Hence, the design of a vaccine strategy able to induce mucosal antibodies and in particular specific IgA, may be crucial to providing immune protection. Nasal immunisation is known to induce specific IgG and IgA responses in the cervicovaginal mucosa; however, there is an urgent need for the development of safe, effective and accessible mucosal adjuvants for nasal application in humans. To reduce the potential for adverse events associated with some nasal adjuvants, we have assessed whether the B‐cell‐activating cytokines APRIL, BAFF and TSLP enhance humoral immune responses to HIV‐1 gp140. Following intranasal immunisation, TSLP but not APRIL or BAFF induced strong humoral responses both in serum and mucosa. The adjuvant effect of TSLP on humoral responses was similar to that of cholera toxin (CT). The use of TSLP as an adjuvant skewed both the cellular and humoral immune responses towards Th2 cells. This is the first time that TSLP has been demonstrated to have a positive effect as a mucosal adjuvant, and specifically to promote mucosal and systemic responses to HIV gp140.

Mucosal delivery of antigen-coated nanoparticles to lungs confers protective immunity against tuberculosis infection in mice.

Mucosal boosting of BCG‐immunised individuals with a subunit tuberculosis (TB) vaccine would be highly desirable, considering that the lungs are the principal port of entry for Mycobacterium tuberculosis (MTB) and the site of the primary infection and reactivation. However, the main roadblock for subunit TB vaccine development is the lack of suitable adjuvants that could induce robust local and systemic immune responses. Here, we describe a novel vaccine delivery system that was designed to mimic, in part, the MTB pathogen itself. The surface of yellow carnauba wax nanoparticles was coated with the highly immunogenic Ag85B Ag of MTB and they were directed to the alveolar epithelial surfaces by the incorporation of the heparin‐binding hemagglutinin adhesion (HBHA) protein. Our results showed that the i.n. immunisation of BCG‐primed BALB/c mice with nanoparticles adsorbed with Ag85B‐HBHA (Nano‐AH vaccine) induced robust humoral and cellular immune responses and IFN‐γ production, and multifunctional CD4+ T cells expressing IFN‐γ, IL‐2 and TNF‐α. Mice challenged with H37Rv MTB had a significantly reduced bacterial load in their lungs when compared with controls immunised with BCG alone. We therefore conclude that this immunisation approach is an effective means of boosting the BCG‐induced anti‐TB immunity.