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Stock KF, Klein BS, Cong MTV, Regenbogen C, Kemmner S, Büttner M, Wagenpfeil S, Matevossian E, Renders L, Heemann U, Küchle C. ARFI-based tissue elasticity quantification and kidney graft dysfunction: first clinical experiences. Clin Hemorheol Microcirc 2012; 49:527-35. [PMID: 22214724 DOI: 10.3233/ch-2011-1503] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
BACKGROUND AND PURPOSE Beyond the medical history, the clinical exam and lab findings, non-invasive ultrasound parameters such as kidney size and Doppler values (e.g. the resistive index) are important tools assisting clinical decision making in the monitoring of renal allografts. The gold standard for the diagnosis of renal allograft dysfunction remains the renal biopsy; while an invasive procedure, the justifiable necessity for this derives from its definitive nature a requirement beyond the synopses of all non-invasive tools. "Acoustic Radiation Force Impulse Imaging"(ARFI)-quantification is a novel ultrasound-based technology measuring tissue elasticity properties. So far experience related to this new method has not been reported in renal transplant follow-up. The purpose of this study was to evaluate changes in ARFI-measurements between clinically stable renal allografts and biopsy-proven transplant dysfunction. METHODS We employed "Virtual Touch™ tissue quantification" (Siemens Acuson, S2000) for the quantitative measurement of tissue stiffness in the cortex of transplant kidneys. We performed initial baseline and later disease-evaluative ultrasound examinations in 8 renal transplant patients in a prospective study design. Patients were first examined during stable allograft function with a routine post-transplant renal ultrasound protocol. A second follow-up examination was carried out on subsequent presentation with transplant dysfunction prior to allograft biopsy and histological evaluation. All patiens were examined using ARFI-quantification (15 measurements/kidney). Resistive indices (RI) were calculated using pulsed-wave Doppler ultrasound, and transplant kidney size was measured on B-mode ultrasound images. All biopsies were evaluated histologically by a reference nephropathologist unaware of the results of the ultrasound studies. Histopathological diagnoses were based on biopsy results, taking clinical and laboratory findings into account. Finally we calculated the relative changes in ARFI-quantification, resistive indices and the absolute change of kidney size on a percentage basis at these defined assessment times and compared the results with the final pathologic diagnosis. RESULTS Histological results enumerated five cases of acute T-cell-mediated rejection, one case of calcineurin inhibitor toxicity and two cases of acute tubular necrosis. Calcineurin inhibitor toxicity and acute tubular necrosis were subsumed as "other pathologies". Mean ARFI-values showed an average increase of more than 15% percent in transplants with histologically proven acute rejection whereas no increase was seen in transplants with other pathologies. Mean RI-values showed no increase either in the diagnostic group of acute rejection, nor in the group with other pathologies. Kidney size showed a mean absolute increase of 0.5 centimetres in allografts with acute rejection, whereas a mean decrease of 0.17 centimetres was seen in the group with other pathologies. CONCLUSION As shown before in other studies, RI values and kidney size are of doubtful utility in the evaluation of kidney allograft dysfunction. ARFI-based elasticity measurement shows promise as a complementary non-invasive parameter in follow-on diagnosis of renal allograft rejection.
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Stock KF, Klein BS, Vo Cong MT, Sarkar O, Römisch M, Regenbogen C, Büttner M, Schuster T, Matevossian E, Amann K, Clevert DA, Heemann U, Küchle C. ARFI-based tissue elasticity quantification in comparison to histology for the diagnosis of renal transplant fibrosis. Clin Hemorheol Microcirc 2011; 46:139-48. [PMID: 21135489 DOI: 10.3233/ch-2010-1340] [Citation(s) in RCA: 74] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
BACKGROUND AND PURPOSE Until recently clinical diagnosis of chronic renal allograft dysfunction could only be established invasively by renal biopsy. Given the risks of that procedure, a non-invasive, diagnostic test would be very advantageous. Novel ultrasound-based elasticity tools, using "Acoustic Radiation Force Impulse (ARFI)" technology are now available. Previously this technique has been utilised to quantify liver fibrosis. First results of these studies are promising. The purpose of our study was to investigate correlation between stiffness values obtained by ARFI-quantification and histological fibrosis score in renal transplants. METHODS We employed "Virtual Touch™ tissue quantification" (Siemens Acuson, S2000) to quantitatively measure tissue stiffness in the cortex of transplant kidneys. Eighteen patients were included in this prospective study, recording close temporal ARFI-quantification and fibrosis measurements. All patients undergoing renal transplant biopsy were examined with ARFI-quantification (15 measurements per transplant kidney). Resistive indices were also calculated from pulsed-wave Doppler ultrasound. Transplant biopsies were histologically evaluated by a reference nephropathologist and graded according to the percentage of fibrosis and to the BANFF-score. Due to the non-normal distribution of the data the Spearman-correlation-coefficient (rho) was used to assess the bivariate relationship of ARFI and fibrosis in the transplant kidney. RESULTS There was a significant positive moderate correlation between mean ARFI-values and the grade of fibrosis (rho = +0.465; p = 0.026). This correlation was also valid for the mean ARFI-values and the BANFF-category (rho = +0.468; p = 0.025). There was no significant correlation between the mean ARFI-values and the resistive indices in the transplant kidney (rho = +0.034; p = 0.904). Nevertheless, a positive correlation between the mean RI-values of the kidney and the grade of fibrosis was established (rho = +0.563; p = 0.015). CONCLUSION The mean values of ARFI measurements and the resistive indices are potentially independent explanation variables for evaluating the grade of fibrosis in transplant kidneys.
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Krajaejun T, Gauthier GM, Rappleye CA, Sullivan TD, Klein BS. Development and application of a green fluorescent protein sentinel system for identification of RNA interference in Blastomyces dermatitidis illuminates the role of septin in morphogenesis and sporulation. EUKARYOTIC CELL 2007; 6:1299-309. [PMID: 17496124 PMCID: PMC1951135 DOI: 10.1128/ec.00401-06] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/16/2006] [Accepted: 05/01/2007] [Indexed: 11/20/2022]
Abstract
A high-throughput strategy for testing gene function would accelerate progress in our understanding of disease pathogenesis for the dimorphic fungus Blastomyces dermatitidis, whose genome is being completed. We developed a green fluorescent protein (GFP) sentinel system of gene silencing to rapidly study genes of unknown function. Using Gateway technology to efficiently generate RNA interference plasmids, we cloned a target gene, "X," next to GFP to create one hairpin to knock down the expression of both genes so that diminished GFP reports target gene expression. To test this approach in B. dermatitidis, we first used LACZ and the virulence gene BAD1 as targets. The level of GFP reliably reported interference of their expression, leading to rapid detection of gene-silenced transformants. We next investigated a previously unstudied gene encoding septin and explored its possible role in morphogenesis and sporulation. A CDC11 septin homolog in B. dermatitidis localized to the neck of budding yeast cells. CDC11-silenced transformants identified with the sentinel system grew slowly as flat or rough colonies on agar. Microscopically, they formed ballooned, distorted yeast cells that failed to bud, and they sporulated poorly as mold. Hence, this GFP sentinel system enables rapid detection of gene silencing and has revealed a pronounced role for septin in morphogenesis, budding, and sporulation of B. dermatitidis.
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Abstract
BACKGROUND Blastomyces dermatitidis, the etiologic agent of blastomycosis, causes severe disease and substantial mortality in those immunocompromised by acquired immunodeficiency syndrome or malignancy. In solid organ transplant recipients, the epidemiology, clinical features, and outcomes have not been fully described. METHODS We conducted a retrospective case-series at the University of Wisconsin Hospital and Clinics. Case patients were solid organ transplant recipients with blastomycosis. RESULTS From 1986 to 2004, we identified 11 cases of post-transplant blastomycosis with 64% occurring between 2000 and 2004. Onset of infection occurred a median of 26 months post transplantation with near equal distribution before and after the first year of transplantation. Rejection did not precede any case of post-transplant blastomycosis. Opportunistic co-infections were common, occurring in 36% of patients. Pneumonia was the most common clinical presentation and was frequently complicated by acute respiratory distress syndrome (ARDS). Extrapulmonary disease predominantly involved the skin and spared the central nervous system. The overall mortality rate was 36%; however, this increased to 67% in those with ARDS. None of the surviving patients relapsed or received routine secondary antifungal prophylaxis. CONCLUSION Blastomycosis is an uncommon infection following solid organ transplantation that is frequently complicated by ARDS, dissemination, and opportunistic co-infection. After cure, post-transplant blastomycosis may not require lifelong antifungal suppression.
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Zhang MX, Brandhorst TT, Kozel TR, Klein BS. Role of glucan and surface protein BAD1 in complement activation by Blastomyces dermatitidis yeast. Infect Immun 2001; 69:7559-64. [PMID: 11705933 PMCID: PMC98847 DOI: 10.1128/iai.69.12.7559-7564.2001] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Our previous studies showed that Blastomyces dermatitidis yeast activates the human complement system, leading to deposition of opsonic complement fragments onto the yeast surface. This report examines the influence of altered surface expression of glucan or BAD1 protein (formerly WI-1) on the yeast's ability to activate and bind C3. Compared to the wild type, a glucan-deficient mutant yeast delayed initiation of C3 deposition and reduced C3-binding capacity by 50%. Linkage of baker's-yeast beta-glucan to the glucan-deficient yeast restored initial C3 deposition kinetics to the wild-type level and partially restored C3-binding capacity, suggesting that beta-glucan is an initiator of complement activation and a C3 acceptor. The role of BAD1 in B. dermatitidis yeast-complement interaction was also assessed. BAD1 knockout yeast initiated faster C3 deposition and increased C3-binding capacity compared to the wild-type yeast or a BAD1-reconstituted yeast, suggesting either a lack of an intrinsic ability in BAD1 or an inhibitory role of BAD1 in complement activation and binding. However, both complement activation and the capacity for C3 binding by the wild-type yeast were enhanced in normal human serum supplemented with an anti-BAD1 monoclonal antibody (MAb) or in immune sera from blastomycosis patients. Microscopic analysis revealed that more initial C3-binding sites were formed on yeast in the presence of both naturally occurring complement initiators and exogenous anti-BAD1 MAb, suggesting that anti-BAD1 antibody enhanced the ability of B. dermatitidis yeast to interact with the host complement system. Thus, glucan and BAD1 have distinctly different regulatory effects on complement activation by B. dermatitidis.
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Finkel-Jimenez B, Wüthrich M, Brandhorst T, Klein BS. The WI-1 adhesin blocks phagocyte TNF-alpha production, imparting pathogenicity on Blastomyces dermatitidis. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2001; 166:2665-73. [PMID: 11160330 DOI: 10.4049/jimmunol.166.4.2665] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The WI-1 adhesin is indispensable for pathogenicity of Blastomyces dermatitidis and is thought to promote pulmonary infection by fixing yeast to lung tissue and cells. Recent findings suggest that WI-1 confers pathogenicity by mechanisms in addition to adherence. Here, we investigated whether WI-1 modulates host immunity by altering production of pro-inflammatory cytokines. Production of TNF-alpha in lung alveolar fluids of mice infected with B. dermatitidis was severalfold higher for WI-1 knockout yeast compared with wild-type yeast, and in vitro coculture of unseparated lung cells with these isogenic yeast disclosed similar differences. Upon coculture with purified macrophages and neutrophils, wild-type yeast blocked TNF-alpha production, yet WI-1 knockout yeast stimulated production. Coating knockout yeast with purified WI-1 converted them from stimulating TNF-alpha production to inhibiting production. Addition of purified WI-1 into stimulated phagocyte cultures led to concentration-dependent inhibition of TNF-alpha production. Neutralization of TNF-alpha in vivo exacerbated experimental pulmonary infection, particularly for the nonpathogenic WI-1 knockout yeast. Inducing increased TNF-alpha levels in the lung by adenovirus-vectored gene therapy controlled infection with wild-type yeast. Thus, the WI-1 adhesin on yeast modulates host immunity through blocking TNF-alpha production by phagocytes, which fosters progression of pulmonary infection.
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MESH Headings
- Adenoviridae/genetics
- Adenoviridae/immunology
- Animals
- Blastomyces/genetics
- Blastomyces/immunology
- Blastomyces/pathogenicity
- Blastomycosis/immunology
- Blastomycosis/microbiology
- Blastomycosis/therapy
- Cell Adhesion/immunology
- Cells, Cultured
- Fungal Proteins/genetics
- Fungal Proteins/metabolism
- Fungal Proteins/toxicity
- Genetic Therapy
- Glycoproteins/deficiency
- Glycoproteins/genetics
- Glycoproteins/metabolism
- Glycoproteins/toxicity
- Intubation, Intratracheal
- Macrophages, Alveolar/immunology
- Macrophages, Alveolar/metabolism
- Macrophages, Alveolar/microbiology
- Macrophages, Peritoneal/immunology
- Macrophages, Peritoneal/metabolism
- Macrophages, Peritoneal/microbiology
- Male
- Mice
- Mice, Inbred BALB C
- Mice, Inbred C57BL
- Neutrophils/immunology
- Neutrophils/metabolism
- Neutrophils/microbiology
- Phagocytosis/genetics
- Phagocytosis/immunology
- Recombinant Proteins/administration & dosage
- Recombinant Proteins/therapeutic use
- Tumor Necrosis Factor-alpha/antagonists & inhibitors
- Tumor Necrosis Factor-alpha/biosynthesis
- Tumor Necrosis Factor-alpha/genetics
- Tumor Necrosis Factor-alpha/physiology
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Rooney PJ, Sullivan TD, Klein BS. Selective expression of the virulence factor BAD1 upon morphogenesis to the pathogenic yeast form of Blastomyces dermatitidis: evidence for transcriptional regulation by a conserved mechanism. Mol Microbiol 2001; 39:875-89. [PMID: 11251809 DOI: 10.1046/j.1365-2958.2001.02300.x] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Most dimorphic fungal pathogens grow as non-pathogenic moulds in soil and convert to pathogenic yeast in the host, suggesting that virulence factors are upregulated during phase transition. Such factors have been difficult to identify. We analysed BAD1 (formerly WI-1), a virulence factor in the dimorphic fungus Blastomyces dermatitidis, for expression in yeast and mycelial morphotypes. BAD1 was expressed in yeast but not in mycelia of North American strains of B. dermatitidis, and this expression pattern was confirmed for BAD1 transcript. BAD1 under the control of its promoter was transferred into African B. dermatitidis lacking a native BAD1 locus, and phase-specific expression was conserved. Sequence similarity was identified between the BAD1 promoter and the promoters of two yeast phase-specific genes in Histoplasma capsulatum. In H. capsulatum BAD1 transformants, yeast phase-specific expression of BAD1 was conserved, and no transcript was detected in mycelia. BAD1 beta-galactosidase reporter fusions analysed in B. dermatitidis and H. capsulatum confirmed that BAD1 is transcriptionally regulated in both fungi. BAD1 promoter activity and surface BAD1 expression were detected 6 h after shifting mycelia to 37 degrees C. Thus, BAD1 is expressed after transition to the pathogenic yeast morphotype and is regulated by a mechanism for phase-specific gene expression that appears to be conserved.
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Wüthrich M, Filutowicz HI, Klein BS. Mutation of the WI-1 gene yields an attenuated blastomyces dermatitidis strain that induces host resistance. J Clin Invest 2000; 106:1381-9. [PMID: 11104791 PMCID: PMC381467 DOI: 10.1172/jci11037] [Citation(s) in RCA: 77] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Systemic fungal infections are becoming more common and difficult to treat, and vaccine prevention is not available. Pulmonary infection with the dimorphic fungus Blastomyces dermatitidis often progresses and requires treatment to prevent fatality. We recently created a recombinant strain of the fungus lacking the WI-1 adhesin and pathogenicity. We show here that administration of viable yeast of this attenuated strain vaccinates against lethal pulmonary experimental infection due to isogenic and nonisogenic strains from diverse geographic regions. To our knowledge, this is the first example of a recombinant attenuated vaccine against fungi. The vaccine induces delayed-type hypersensitivity and polarized type 1 cytokine responses, which are linked with resistance. A cell-wall/membrane (CW/M) antigen from the vaccine strain also induces polarized and protective immune responses. Lymph node cells and CD4(+) T-cell lines raised with CW/M antigen transfer protective immunity when they release type 1 cytokine IFN-gamma, but not when they release IL-4, and neutralization of IFN-gamma confirmed its role in vivo. Thus, by mutating a pathogenetic locus in a dimorphic fungus, we have created an attenuated vaccine strain and have begun to elucidate fungal and host elements requisite for vaccine immunity.
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Wüthrich M, Finkel-Jiminez BE, Klein BS. Interleukin 12 as an adjuvant to WI-1 adhesin immunization augments delayed-type hypersensitivity, shifts the subclass distribution of immunoglobulin G antibodies, and enhances protective immunity to Blastomyces dermatitidis infection. Infect Immun 2000; 68:7172-4. [PMID: 11083850 PMCID: PMC97835 DOI: 10.1128/iai.68.12.7172-7174.2000] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Cell-mediated immunity is pivotal in host resistance to Blastomyces dermatitidis infection. Immunization of mice with the WI-1 adhesin enhances resistance against experimental pulmonary infection but elicits features of a mixed T-helper-cell immune response. Immune mice acquire delayed-type hypersensitivity (DTH) but also high titers of WI-1-specific immunoglobulin G1 (IgG1) and IgG2b, a result indicative of T-helper-2 cellular immunity. We report that interleukin-12, used as an adjuvant for WI-1 immunization, augments DTH, shifts the balance of the T-helper phenotype toward Th1, and enhances resistance to B. dermatitidis infection.
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Abstract
Many fungal pathogens are opportunistic, that is, they infect individuals who have a compromised immune system. Histoplasma capsulatum is a common pathogenic fungus that lives happily inside the phagosomes of macrophages. As Klein explains in his Perspective, an important H. capsulatum virulence factor, CBP1, has been found, which mops up free calcium ions within the phagosome, enabling the yeast to live under calcium-poor conditions (Sebhgati et al.). Chelating calcium ions may also have the added benefit that when the phagosome fuses with the lysosome, destructive lysosomal enzymes that require calcium ions for activity remain inactive.
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Klein BS. Molecular basis of pathogenicity in Blastomyces dermatitidis: the importance of adhesion. Curr Opin Microbiol 2000; 3:339-43. [PMID: 10972490 DOI: 10.1016/s1369-5274(00)00100-4] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
An understanding of the molecular bases of pathogenicity in Blastomyces dermatitidis and related systemic dimorphic fungi has been limited until recent years. Yeast cells of B. dermatitidis display an adhesion promoting protein termed WI-1. Recent studies entailing homologous gene targeting and mutation of WI-1 have provided null mutants at this locus and demonstrated the crucial role of the WI-1 adhesin in pathogenesis of blastomycosis. Ongoing studies are pointing to a link between phase-specific expression of WI-1 and the observation that transition to yeast cells is essential for the acquisition of pathogenicity by B. dermatitidis. Recombinant attenuated yeast that lack WI-1 are serving as invaluable tools for induction of vaccine resistance and are pointing to new insights about adaptive immunity to B. dermatitidis.
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Klein BS, Himmelbauer H, Zechner U, Riemann M, Liptay S, Hameister H, Schmid RM. Assignment of the mouse Rbpsuh gene to chromosome 5 and one processed pseudogene Rbpsuh-rs3 to chromosome 6. CYTOGENETICS AND CELL GENETICS 2000; 88:218-20. [PMID: 10828593 DOI: 10.1159/000015554] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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Wüthrich M, Klein BS. Investigation of anti-WI-1 adhesin antibody-mediated protection in experimental pulmonary blastomycosis. J Infect Dis 2000; 181:1720-8. [PMID: 10823774 DOI: 10.1086/315473] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/1999] [Revised: 01/14/2000] [Indexed: 11/03/2022] Open
Abstract
Infection with Blastomyces dermatitidis elicits strong antibody responses to the surface adhesin WI-1. The antibodies are directed chiefly against the adhesive domain, a 25-amino-acid repeat. Tandem-repeat-specific monoclonal antibodies (mAbs) were studied for their opsonic activity in vitro and their capacity to adoptively transfer protection in murine experimental blastomycosis. mAbs to WI-1 enhanced binding and entry of B. dermatitidis yeasts into J774. 16 cells but did not enhance killing or growth inhibition of the yeast. Passive transfer of 8 mAbs to WI-1 into 3 different inbred strains of mice also did not improve the course of experimental infection and sometimes worsened it. mu-deficient mice were more resistant to experimental blastomycosis than were intact littermates, and passive transfer of the mAbs into these mice did not protect them against experimental infection. Thus, antibody to WI-1 does not appear to improve the outcome of murine blastomycosis and may enhance the infection.
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Klein BS, Squires RA, Lloyd JK, Ruge DR, Legendre AM. Canine antibody response to Blastomyces dermatitidis WI-1 antigen. Am J Vet Res 2000; 61:554-8. [PMID: 10803652 DOI: 10.2460/ajvr.2000.61.554] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
OBJECTIVE To assess whether dogs with blastomycosis produce antibodies against the WI-1 and A-antigens of Blastomyces dermatitidis and whether the antibodies are useful in serodiagnosis. SAMPLE POPULATION 359 serum samples obtained from 245 dogs. PROCEDURE 233 samples from 122 dogs with blastomycosis, and 1 sample each from 24 dogs with suspected blastomycosis, 51 control dogs without infection, and 48 healthy dogs from an enzootic region were obtained. Antibodies against WI-1 antigen were detected by radioimmunoassay (RIA). Serum samples were tested in parallel for antibodies against the A-antigen of B dermatitidis by commercial agar-gel immunodiffusion (AGID) in a reference laboratory. RESULTS Antibodies were detected in 92% of infected dogs by RIA and in 41 % by AGID. For 29 serum samples that were obtained 11 to 1,545 days after diagnosis, antibodies were detected in 92% of samples by RIA and 7% by AGID. For 93 serial serum samples from 29 dogs with blastomycosis, the mean anti-WI-1 titer was 1:18,761 at the time of diagnosis, and decreased to a mean of 1:1,338 by 210 days after treatment was initiated. Of 24 dogs with suspected infection, antibodies were detected in 67% by RIA and 33% by AGID. Control dogs without blastomycosis had no detectable antibodies in either assay. Thus, sensitivity was 92% for RIA and 41 % for AGID, and specificity was 100% for both tests. CONCLUSIONS AND CLINICAL RELEVANCE Anti-WI-1 antibodies are readily detected by RIA in dogs with blastomycosis. Titers become high, decline during treatment, and persist for months. Anti-A antibodies are sometimes detected with AGID, but these decrease quickly.
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Chang WL, Audet RG, Aizenstein BD, Hogan LH, DeMars RI, Klein BS. T-Cell epitopes and human leukocyte antigen restriction elements of an immunodominant antigen of Blastomyces dermatitidis. Infect Immun 2000; 68:502-10. [PMID: 10639410 PMCID: PMC97169 DOI: 10.1128/iai.68.2.502-510.2000] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Humans infected with the dimorphic fungus Blastomyces dermatitidis develop strong T-lymphocyte responses to WI-1, an immunodominant antigen that has been shown to elicit protective immunity in mice. In the present study, the T-cell epitopes of WI-1 and human leukocyte antigen (HLA) restricting elements that display them were investigated. Peripheral blood mononuclear cells (PBMC) from 37 patients with a confirmed history of blastomycosis were tested for a response to WI-1 in primary proliferation assays; PBMC from 35 (95%) responded. Six patients whose PBMC proliferated strongly in response to WI-1 (defined as a stimulation index greater than 50) were tested further for responses to subcloned, recombinant fragments of the antigen. These patients responded chiefly to sequences within the N terminus and the 25-amino-acid tandem repeat. Cloned CD4(+) T cells from an infected individual were used to delineate more precisely the peptide epitopes in the fragments and HLA restricting elements that present them. A majority of the T-cell clones recognized an epitope spanning amino acids 149 to 172 within the N terminus, displayed by HLA-DR 15. A minority of the clones, which have been shown to perform a cytolytic function in vitro, recognized an epitope in the tandem repeat displayed by HLA-DPw4, an uncommon restricting element. Tandem repeat epitopes required display by the beta chain of DPw4 heterodimers. Thus, human T cells with different functions in vitro also recognize distinct regions of WI-1, raising the possibility that HLA restricting elements that present them could modulate immunity during blastomycosis by selection and display of WI-1 peptides.
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Klein BS, Liptay S, Schmid RM, Hameister H. Assignment of Nfkbib to murine chromosome bands 7A3-B3 by in situ hybridization. CYTOGENETICS AND CELL GENETICS 1999; 85:308-9. [PMID: 10449924 DOI: 10.1159/000015283] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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Wüthrich M, Chang WL, Klein BS. Immunogenicity and protective efficacy of the WI-1 adhesin of Blastomyces dermatitidis. Infect Immun 1998; 66:5443-9. [PMID: 9784555 PMCID: PMC108681 DOI: 10.1128/iai.66.11.5443-5449.1998] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
People infected with Blastomyces dermatitidis develop strong immunity to the yeast surface adhesin WI-1, including antibody responses to the adhesive domain, a 25-amino-acid repeat, and cellular responses to the N terminus. We studied the immunogenicity of WI-1 and the ability of anti-WI-1 immune responses to protect against lethal pulmonary infection in mice. WI-1 immunization, given in Freund's adjuvant subcutaneously in two doses 2 weeks apart, evoked delayed hypersensitivity responses in a concentration-dependent manner. Immunized mice also had anti-WI-1 antibody responses, with titers reaching an endpoint dilution of approximately 1:800,000. Anti-WI-1 immunoglobulin G (IgG) antibody subclasses were IgG1 > IgG2b > IgG2a > IgG3, indicating a mixed T helper 1 and T helper 2 immune response. In protection experiments, WI-1 immunization significantly prolonged the survival of C57BL/6 and BALB/c mice compared to controls following intranasal administration of a lethal dose of B. dermatitidis yeasts (Kaplan-Meier survival curve P values of 0.027 to 0.0002) and also protected a proportion of the animals from death due to progressive pulmonary blastomycosis. Taken together, our results suggest that administration of WI-1 raises antibody and cell-mediated immune responses, which enhance resistance against pulmonary infection with B. dermatitidis. Mechanisms of vaccine-induced resistance require further investigation.
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Chang WL, van der Heyde HC, Klein BS. Flow cytometric quantitation of yeast a novel technique for use in animal model work and in vitro immunologic assays. J Immunol Methods 1998; 211:51-63. [PMID: 9617831 DOI: 10.1016/s0022-1759(97)00191-9] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Animal models of fungal and other infectious diseases often require that the number of organisms in tissue be quantified, traditionally by grinding organs, plating them on agar and counting colony forming units (CFU). This method is labor intensive, slow as some fungi require two weeks of culture and limited in reliability by poor plating efficiency. To circumvent these problems, we developed a flow cytometric method to quantify yeast. In vitro cultured Blastomyces dermatitidis, Cryptococcus neoformans, Candida albicans and Histoplasma capsulatum yeast were labelled with specific monoclonal or polyclonal antibodies to stain surface determinants or with Calcofluor to stain cell-wall chitin. A defined number of fluorescently labelled beads were added prior to acquisition by flow cytometry as a reference standard for quantitation. Beads were readily distinguished from yeast by forward scatter, side scatter and intensity of fluorescence. Cultured yeast were enumerated by both standard CFU determination and flow cytometry in a range of 10(2) to 10(7) cells. Only flow cytometry enabled discrimination of live and dead yeast by using appropriate fluorescent dyes. The flow cytometric method was applied to murine models of histoplasmosis and blastomycosis to quantify the burden of fungi in the lungs of infected mice. Labelling yeast with Calcofluor alone resulted in unacceptably high levels of nonspecific binding to mouse cell debris. In contrast, labelling H. capsulatum with a rabbit polyclonal antiserum and B. dermatitidis with a monoclonal antibody to the surface protein WI-1 permitted accurate quantitation. We conclude that this flow cytometry technique is rapid, efficient and reliable for quantifying the burden of infection in animal models of fungal disease. The technique also should lend itself to performing cytotoxicity assays that require discrimination of live and dead fungi, or phagocytosis assays that require discrimination of intracellular and extracellular organisms.
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Klein BS. Role of cell surface molecules of Blastomyces dermatitidis in the pathogenesis and immunobiology of blastomycosis. SEMINARS IN RESPIRATORY INFECTIONS 1997; 12:198-205. [PMID: 9313291] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
The cell surface of pathogenic microbes is critical in directing their interactions with the host. The discovery of a 120 kd antigen/adhesin WI-1 on the yeast or parasitic form of Blastomyces dermatitidis has elucidated the molecular basis of host/pathogen interactions in blastomycosis. WI-1 has three structural domains: (1) an N-terminal hydrophobic domain that spans the cell membrane, (2) a C-terminal epidermal growth factor-like domain that may bind extracellular matrix, and (3) a central domain of many 24- or 25 amino-acid repeats arrayed in tandem. The repeat is homologous to invasin, a Yersinia adhesin, and binds CD11b/CD18 (CR3) and CD14 receptors on host cells. WI-1 expression is altered on genetically related strains of B dermatitidis differing in virulence and modulates how hypovirulent mutants interact with macrophages. WI-1 also evokes humoral and cell-mediated immune responses in acquired resistance to B dermatitidis that may help clear the fungus in the host. These observations on WI-1 provide new insight into a key pathogenic factor and antigen of the fungus and may ultimately help in designing new ways to diagnose, treat, and prevent blastomycosis.
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Klein BS, Aizenstein BD, Hogan LH. African strains of Blastomyces dermatitidis that do not express surface adhesin WI-1. Infect Immun 1997; 65:1505-9. [PMID: 9119493 PMCID: PMC175159 DOI: 10.1128/iai.65.4.1505-1509.1997] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
African strains of Blastomyces dermatitidis differ from North American strains in their growth, morphology, and clinical disease phenotype. In addition, two serotypes, designated 1 and 2, have been described. We investigated African strains of B. dermatitidis for expression of the surface protein adhesin WI-1 and found that serotype 2 strains do not express it because they lack the coding sequence in their genome. The defect will make the strains useful for gene complementation and for testing the pathogenetic role of the WI-1 adhesin.
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Hogan LH, Klein BS. Transforming DNA integrates at multiple sites in the dimorphic fungal pathogen Blastomyces dermatitidis. Gene 1997; 186:219-26. [PMID: 9074500 DOI: 10.1016/s0378-1119(96)00713-5] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Blastomyces dermatitidis is a primary fungal pathogen of man and other mammals, but like many other human fungal pathogens, relatively little is known about the factors that account for its virulence and pathogenicity. We developed a transformation system to facilitate molecular genetic studies of putative virulence factors from B. dermatitidis. Transformation of the multinucleate yeasts was achieved by electroporation of DNAs containing a dominant selectable marker, hygromycin B (HygB) resistance. Southern analysis showed that transforming DNA invariably integrated ectopically into the chromosome. No evidence was found for extrachromosomal DNA. The HygB resistance could be expressed by either a 375-bp promoter fragment of the B. dermatitidis WI-1 gene encoding adhesin or an Aspergillus gpdA promoter placed 5' of the E. coli hph gene. Primer extension analysis showed that for plasmids containing the WI-1 promoter, transcription of the hph gene initiated within the 375-bp WI-1 promoter fragment. The combination of gene transfer and two promoters capable of independent transcription will allow us to restore or augment gene expression in appropriate strains and test an influence on virulence. Molecular genetic manipulation of B. dermatitidis represents a major advance in our ability to investigate the pathogenesis of blastomycosis and other similar fungal diseases.
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Abstract
Human fungal pathogens have become an increasingly important medical problem with the explosion in the number of immunocompromised patients as a result of cancer, steroid therapy, chemotherapy, and AIDS. Additionally, the globalization of travel and expansion of humankind into previously undisturbed habitats have led to the reemergence of old fungi and new exposure to previously undescribed fungi. Until recently, relatively little was known about virulence factors for the medically important fungi. With the advent of molecular genetics, rapid progress has now been made in understanding the basis of pathogenicity for organisms such as Aspergillus species and Cryptococcus neoformans. The twin technologies of genetic transformation and "knockout" deletion construction allowed for genetic tests of virulence factors in these organisms. Such knowledge will prove invaluable for the rational design of antifungal therapies. Putative virulence factors and attributes are reviewed for Aspergillus species, C. neoformans, the dimorphic fungal pathogens, and others, with a focus upon a molecular genetic approach. Candida species are excluded from coverage, having been the subject of numerous recent reviews. This growing body of knowledge about fungal pathogens and their virulence factors will significantly aid efforts to treat the serious diseases they cause.
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Klein BS, Newman SL. Role of cell-surface molecules of Blastomyces dermatitidis in host-pathogen interactions. Trends Microbiol 1996; 4:246-51. [PMID: 8795162 DOI: 10.1016/0966-842x(96)10028-7] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
The fungal pathogen Blastomyces dermatitidis produces an adhesin (WI-1) in yeast stages, which contains repetitive regions that bind host-cell receptors. Adhesin and glucan may modulate fungal interactions with macrophages; their level of expression is altered in hypovirulent mutants. Adhesin is also involved in immune responses, and may be important in eliciting the clearance of the fungus.
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Hogan LH, Josvai S, Klein BS. Genomic cloning, characterization, and functional analysis of the major surface adhesin WI-1 on Blastomyces dermatitidis yeasts. J Biol Chem 1995; 270:30725-32. [PMID: 8530512 DOI: 10.1074/jbc.270.51.30725] [Citation(s) in RCA: 54] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
WI-1 is a 120-kDa surface protein adhesin on Blastomyces dermatitidis yeasts that binds CD18 and CD14 receptors on human macrophages. We isolated and analyzed a clone of genomic WI-1 to characterize this key adherence mechanism of the yeast. The 9.3-kilobase insert contains an open reading frame of 3438 nucleotides and no introns. The amino acid sequence of native WI-1 matches the deduced sequence of genomic WI-1 at positions 757-769, 901-913, and 1119-1138, demonstrating the cloned gene is authentic WI-1. The complete coding sequence has 30 highly conserved repeats of 24 amino acids arrayed in tandem in two noncontiguous regions of the protein. The repeat sequence is homologous to the Yersiniae adhesin invasin, the C terminus displays an epidermal growth factor-like domain, and the N terminus has a short hydrophobic sequence that may be a membrane-spanning domain. The tandem repeats are predicted to be at the exposed surface of the protein, thereby explaining the adhesive properties of WI-1. The WI-1 promoter contains a CAAT box (nucleotide positions 2287-2290), TATA box (2380-2385), and CT motif (2399-2508). Transcription is initiated within the CT motif at nucleotide 2431. A 5.5-kilobase subclone containing the full coding sequence of WI-1 was expressed as a histidine-tagged fusion protein in Escherichia coli. Recombinant WI-1 has the expected molecular mass of 120 kDa, is strongly recognized in Western blots by rabbit anti-WI-1 antiserum, and binds human macrophage receptors in the same manner as native WI-1. This work clarifies a key adherence mechanism of B. dermatitidis and will permit further analysis of WI-1-mediated attachment to host cells, receptors, and extracellular matrix.
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Newman SL, Chaturvedi S, Klein BS. The WI-1 antigen of Blastomyces dermatitidis yeasts mediates binding to human macrophage CD11b/CD18 (CR3) and CD14. THE JOURNAL OF IMMUNOLOGY 1995. [DOI: 10.4049/jimmunol.154.2.753] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Abstract
Three genetically related strains of Blastomyces dermatitidis (Bd) yeasts that differ in their expression of WI-1, an immunodominant cell wall Ag, were tested for their capacity to bind to human macrophages (M phi) in the absence of serum. These strains included American Type Culture Collection (ATCC, Rockville, MD) ATCC 26199, which is virulent for mice; an attenuated mutant strain ATCC 60915, which expresses 2.5-fold more WI-1 than strain 26199; and an avirulent mutant strain, ATCC 60916, which has sixfold more WI-1 than strain 26199. Attachment of both mutant strains to M phi was rapid and was maximum after 10 min at 37 degrees C. Attachment of strain 26199 to M phi was approximately 40% of that obtained with the mutants. Binding of Bd to M phi was temperature- and Mg(2+)-dependent, and heat-killed yeasts bound to M phi as well as viable yeasts. Experiments with receptor-specific mAbs demonstrated that 26199 yeasts bound predominantly to the LPS binding site on CD11b/CD18 (CR3). However, the mutants bound to M phi CD14 as well as CR3. Fab anti-WI-1 inhibited the binding of all strains to M phi by 69 to 78%. Latex microspheres coated with purified WI-1 or a 25-amino acid tandem repeat located within WI-1 also bound to M phi CR3 and CD14. These data demonstrate that: 1) WI-1 is a major ligand on Bd that mediates attachment of yeasts to human M phi; 2) the binding activity of WI-1 is located within the 25-amino acid tandem repeat; and 3) binding of Bd yeasts to M phi is mediated through the LPS binding site on CR3 and CD14.
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