Immune and autoimmune responses to HIV-1 in mucosa and other tissues
Abstract: The aim of these studies was to evaluate routes and devices for administration of HIV-1 DNA vaccines. In particular we were interested in mucosal routes for the induction of immunity at mucosal surfaces. We studied the effects of a novel mucosal route, jet-injection, for induction of systemic and local responses. This technique was found to be a rapid and easy way of adminisering plasmid DNA. A combination of the genes encoding the HIV-1 regulatory proteins rev, nef, tat and the structural genes gp160 and p24 was administered by intramuscular, intradermal and mucosal routes. B cell responses measured by in vitro B cell Ig production and serology showed high titers and high frequencies of IgG and IgA induction. The jet-injection technique elicited predominantly IgG2a and was able to induce local mucosal IgA and IgG antibodies. Intranasal administration of the plasmids induced mucosal IgA, found in lung washings, faeces and vagina, as well as high titers of humoral systemic responses. Continued immunization also induced cytotoxic T cells after intramuscular injections. Mucosal jet-injections and intramuscular injections of HIV-1 DNA constructs encoding the nef, rev, and tat regulatory genes were evaluated in humans. Mucosal and systemic IgA and IgG specific for the gene products were present during the vaccination but were not increased. This was at variance with the non-infected animals. Oral mucosal transudate collected from the site of immunization was analyzed for mucosal cytokines. IFNg and IL-2 were synthesized at the local site. High concentrations of IL-2 were induced and persisted for several months. Analysis of mucosal biopsies from the site of immunization revealed a massive infiltration of mononucleated cells as well as granulocytes at various depths of the biopsy on the vaccinated side compared to the control side. Inflammatory T-cell subsets on the immunized side consist of both CD4 + and CD8 + T-cells. The majority of these T-cells expressed the memory phenotype CD45 RO. Additional signs of activation were the increased expression of HLA-DR associated invariant chain (CD74) and increased presence of dendritic cells (S-100) both in the epithelium and in the underlying T-cell infiltrate. Thus, Th1 responses were preferentially induced with the mucosal jet-injection technique in preclinical animal studies, as well as in the clinical trial with HIV infected humans. The possibility that disease progression would be accentuated by autoimmune induction was evaluated in the light of several reports on gp160/HLA molecular mimicry and anti-leucocyte immunity in HIV infected individuals. Could autoantibodies be induced by immunization? Sera from individuals vaccinated with HIV-1 envelope antigen rgp160 revealed low levels of hum-oral responses to synthetic peptides representing defined regions reported to exhibit molecular mimicry to self-antigens. Although autoimmunity in HIV-1 infection may play a role in the pathogenesis of HIV-1 progression to AIDS, rpg160 immunization did not contribute to elevated levels of autoimmune antibodies. Malignancies in the lymphoid system may alter the B cell responses to HIV-1. This hypothesis was tested in patients with HIV-1 related lymphoma. The lymphoma patients with low levels of CD4 + cells had responses similar to asymptomatic patients. Symptomatic patients, on the other hand, exhibited high levels of IgG subclasses to HIV-1 antigens. The patterns of IgG subclass reactivities were also broader than those for either the asymptomatic or the lymphoma patients. This indicates an extensive effect on the humoral immune response in progression of HIV infection.
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