Glucuronoxylomannan in theCryptococcusspecies capsule as a target for CAR+T-cell therapy (original) (raw)
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Microorganisms, 2021
Cryptococcosis, a systemic mycosis that affects both the immunocompromised and immunocompetent, is caused by the inhalation of dehydrated yeasts or fungal spores of Cryptococcus gattii or Cryptococcus neoformans. The Cryptococcus spp. polysaccharide capsule is composed mainly of glucuronoxylomannan—GXM, its major virulence factor. The capsule thickness increases to more than 15 μm during titanization, favoring the pathogenesis of cryptococcosis. Previous studies demonstrated that cytotoxic T cells that had been bioengineered with GXM-targeting chimeric antigen receptor (GXMR-CAR) were able to recognize C. neoformans by promoting the control of titanization. GXMR-CAR, a second-generation CAR, contains a single-chain variable fragment that originates from a 18B7 clone: a human IgG4 hinge, followed by a human CD28 (transmembrane/cytoplasmic domains) and a CD3ς chain. In the current study, we redirected T cells to target distinct C. neoformans and C. gattii cell types by GXMR-CAR. Lenti...
Cells
Chimeric antigen receptors (CARs) redirect T cells to recognize a specific target. CAR components play a pivotal role in antigen specificity, structure stability, expression on cell surface, and induction of cellular activation, which together determine the success of CAR T-cell therapy. CAR products targeting B-cell lymphoma encouraged the development of new CAR applications beyond cancer. For example, our group developed a CAR to specifically target glucuronoxylomannan (GXM) in the capsule of Cryptococcus species, called GXMR-CAR or GXMR-IgG4-28ζ. Cryptococcus are fungi that cause the life-threatening disease cryptococcosis, and GXMR-IgG4-28ζ redirected T cells to target yeast and titan cell forms of Cryptococcus spp. Here, we replaced the IgG4-hinge and CD28-transmembrane domains from GXMR-CAR with a CD8α molecule as the hinge/transmembrane and used CD28 or 4-1BB molecules as co-stimulatory domains, creating GXMR-8-28ζ and GXMR-8-BBζ, respectively. Jurkat cells expressing GXMR-CA...
Immunotherapy, 2011
Cryptococcus neoformans is an opportunistic fungal pathogen responsible for life-threatening infections in immunocompromised individuals and occasionally in those with no known immune impairment. The fungus is endowed with several virulence factors, including capsular polysaccharides that play a key role in virulence. The capsule is composed of 90–95% glucuronoxylomannan (GXM), 5–8% galactoxylomannan (GalXM) and <1% mannoproteins. Capsular polysaccharides are shed into tissue where they produce many deleterious effects. Since GalXM has a smaller molecular mass, the molar concentration of GalXM in polysaccharide that is shed could exceed that of GXM in C. neoformans exopolysaccharides. Moreover, GalXM exhibits a number of unusual biologic properties both in vitro and in vivo. Here, we summarize the principal immunomodulatory effects of GalXM described during the last 20 years, particularly the mechanisms leading to induction of apoptosis in T lymphocytes, B lymphocytes and macroph...
2004
Peptide mimotopes of capsular polysaccharides have been proposed as antigens for vaccines against encapsulated pathogens. In this study, we determined the antibody response to and efficacy of P13, a peptide mimetic of the Cryptococcus neoformans capsular polysaccharide glucuronoxylomannan (GXM), in mice that produce human antibodies. P13 was conjugated to tetanus toxoid (TT) or diphtheria toxoid (DT) and administered subcutaneously in Alhydrogel with or without CpG to mice transgenic for human immunoglobulin loci (XenoMouse mice) and expressing either immunoglobulin G2 (IgG2) (G2 mice) or IgG4 (G4 mice). Mice were vaccinated and revaccinated two or three times. The serum antibody responses of the mice to GXM and P13 and antibody idiotype expression were analyzed by an enzyme-linked immunosorbent assay. The results showed that both P13-TT and P13-DT were antigenic, inducing a mimetic response to P13 in both G2 and G4 mice, and immunogenic, inducing a mimotope response including VH3 (idiotype)-positive antibodies to GXM in G2 but not G4 mice. CpG led to higher titers of IgG to P13 and GXM in P13-TT-vaccinated G2 mice. C. neoformans challenge of P13-protein conjugate-vaccinated and control G2 mice induced anamnestic IgG- and VH3-positive responses to GXM and was associated with a significantly decreased risk of death and a prolongation of survival in P13-DT-vaccinated mice compared to phosphate-buffered saline-treated or protein carrier-vaccinated mice. These findings reveal that P13 elicited a human antibody response with VH3 expression in human immunoglobulin transgenic mice that has been observed for human antibodies to GXM and support the concept that peptide mimotope-based vaccines may hold promise for the treatment of C. neoformans infections.
Biomédica : revista del Instituto Nacional de Salud, 2005
Cryptococcus neoformans is a widely disseminated fungus shown to be responsible for infections in individuals with impaired cell mediated immunity, such as patients with human immunodeficiency virus (HIV). Cryptococcus neoformans has a polysaccharide capsule composed of glucuronoxylomannan (GXM), which acts as a major virulence factor and is considered to be a thymus independent type-2 antigen (TI-2). In the current study, the production kinetics were evaluated for IgG subclasses specific for GXM, and assessed with the cross reactive antibodies to Streptococcus pneumoniae polysaccharide. In addition, spleen B cell subpopulations were quantified in murine models of cryptococcosis with different susceptibilities to the infection. Antibodies were detected by ELISA at different time intervals after C. neoformans infection in moderately resistant (Balb/c), highly resistant (CBA/j) and susceptible (C57BL/6) mouse strains. B cells subpopulations were determined by flow cytometry analysis. ...
T cells cooperate with passive antibody to modify Cryptococcus neoformans infection in mice
Proceedings of the National Academy of Sciences, 1997
Cryptococcus neoformans is an encapsulated fungus that is a major cause of meningitis in patients with AIDS. In immunocompetent mice, administration of IgG1 mAb protects against cryptococcal infection, whereas administration of IgG3 is not protective and can accelerate the infection. In beige mice with impaired natural killer cell function, the effects of IgG1 and IgG3 are similar to those observed in immunocompetent mice, suggesting that natural killer cells are not crucial for antibody-mediated modulation of cryptococcal infection. In mice lacking CD4 ؉ T cells, IgG1 is not protective and IgG3 accelerates infection, indicating that CD4 ؉ T cells are required for antibody-mediated protection. In mice lacking CD8 ؉ T cells, both IgG1 and IgG3 antibodies prolong survival, indicating that acceleration of the disease process by IgG3 involves CD8 ؉ T cells. Both IgG1mediated protection and IgG3-mediated acceleration of infection require interferon ␥. These results reveal a functional dependence of passively administered antibody on cellular immunity in cryptococcal infection in mice and have implications for antibody-based therapies in humans in the setting of CD4 ؉ lymphopenia.
Immunology, 1997
A hallmark of infection with Cryptococcus neoformans is depression of the immune system characterized by poor inflammatory responses and loss of delayed-type hypersensitivity (DTH ) and antibody responses. T-suppressor cell ( Ts) responses, elicited by the capsular polysaccharide (GXM ) of the organism, are known to develop during infection. This study was undertaken to develop a method to inhibit the anti-GXM Ts response and thereby study the influence of the Ts response on immune responsiveness and survival in cryptococcosis. Antigen-presenting cells (APC ), elicited with complete Freund's adjuvant (CFA), were treated in vitro with GXM (GXM-APC ). The GXM-APC were injected intravenously into normal mice. These mice were resistant to induction of anti-GXM Ts cells when soluble GXM was administered in tolerogenic doses or when animals were infected with C. neoformans. Inhibition of the anti-GXM Ts response was specific to GXM as levan-APC did not inhibit induction of anti-GXM Ts cells. Inhibition of the anti-GXM Ts response could not be attributed to increased clearance of GXM due to induction of anti-GXM antibodies or other mechanisms. Anti-cryptococcal DTH responses were lost in mice by the second week of infection. However, treatment with GXM-APC, but not levan-APC, allowed mice to maintain their DTH response. GXM-APC pretreatment enhanced survival of infected mice compared with mice pretreated with levan-APC. These results show that GXM-APC induces immune responses that inhibit the induction of Ts responses and enhances DTH responses in infected mice. These responses correlate with enhanced survival after cryptococcal infection.