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Biomedical subjects

S H Kaufmann

Publications and source records attributed to S H Kaufmann.

At least 127 records · Page 7Linked to original sources
PubMed1999

Development of novel tuberculosis vaccines.

Efficacious control of tuberculosis (TB), one of the world's major health threats, is best achieved by a combination of chemotherapy and vaccination. The current vaccine, BCG, fails to prevent pulmonary TB in adults, which is the most prevalent form of this disease. Consequently, the design of novel vaccines against TB is urgently required. Because the acquired immune response is mediated by different T-cell sets, an optimal combination of these populations must be stimulated. As one third of the world's population is already infected with Mycobacterium tuberculosis, two types of vaccine may be required: one for eradication of already established infection and the other for prompt combat of invading microbes. A rational judgement on the efficacy of the different types of vaccine currently under development needs to await further evaluation.

Antigens, Bacterial↗
PubMed1999

Autoimmune intestinal pathology induced by hsp60-specific CD8 T cells.

Due to their ubiquitous distribution and high degree of structural similarity, heat shock proteins (hsp) are potential target antigens in autoimmune diseases. Here, we describe induction of intestinal inflammation following transfer of hsp60-reactive CD8 T cells into mice. Inflammatory reactions were MHC class I dependent and developed primarily in the small intestine. IFN gamma and TNF alpha, as well as gut-derived hsp60, were elevated at sites of T cell infiltration. Intestinal lesions were drastically reduced in mice lacking receptors for TNF alpha. Pathology also developed in germ-free mice, indicating recognition of host-derived hsp60 by CD8 T cells. This report demonstrates that CD8 T cells with defined antigen specificity cause intestinal inflammation, emphasizing a link between infection and autoimmune disease.

Animals↗
PubMed1999

Participation of group 2 CD1 molecules in the control of murine tuberculosis.

Besides the classical major histocompatibility complex (MHC) class I and MHC class II molecules, human CD1 molecules have been shown to present mycobacterial antigens in vitro. In this study, in vivo treatment of mice with anti-CD1 monoclonal antibodies resulted in exacerbated tuberculosis at very early time points. In CD1-modulated mice, Mycobacterium tuberculosis-specific production of the type 1 cytokines, IL-12, TNF, and IFN-gamma as well as of TGF beta was reduced. These findings suggest an antigen-presenting role of CD1 molecules in tuberculosis.

Animals↗
PubMed1999

Introduction of protein or DNA delivered via recombinant Salmonella typhimurium into the major histocompatibility complex class I presentation pathway of macrophages.

Recombinant (r) Salmonella typhimurium aroA strains which display the hen egg ovalbumin OVA(257-264) peptide SIINFEKL in secreted form were constructed. In addition, attenuated rS. typhimurium pcDNA-OVA constructs harbouring a eukaryotic expression plasmid encoding complete OVA were used to introduce the immunodominant OVA(257-264) epitope into the major histocompatibility complex (MHC) class I presentation pathway. Both modes of antigen delivery (DNA and protein) by Salmonella vaccine carriers stimulated OVA(257-264)-specific CD8 T-cell hybridomas. An in vitro infection system was established that allowed both rSalmonella carrier devices to facilitate MHC class I delivery of OVA(257-264) by coexpression of listeriolysin (Hly) or by coinfection with rS. typhimurium Hlys (Hess J., Gentschev I., Miko D., Welzel M., Ladel C., Goebel W., Kaufmann S.H.E., Proc. Natl. Acad. Sci. USA 93 (1996) 1458-1463). Coexpression of Hly and coinfection with rS. typhimurium Hlys slightly improved MHC class I processing of OVA. Our data provide further evidence for the feasibility of attenuated, Hly-expressing rS. typhimurium carriers secreting heterologous antigens or harbouring heterologous DNA as effective vaccines for stimulating CD8 T cells in addition to CD4 T cells.

Amino Acid Sequence↗
PubMed1999

Cytolytic T-cell responses to human dendritic cells and macrophages infected with Mycobacterium bovis BCG and recombinant BCG secreting listeriolysin.

Cytolytic T-cell responses from 63 normal blood donors were monitored in a Mycobacterium bovis BCG infection system in vitro. We wanted to know whether cultured dendritic cells were capable of potentiating the cytolytic T-cell responses to M. bovis BCG. Infected cultured dendritic cells were up to ten times more effective antigen-presenting cells than macrophages in proliferative assays, while cytolytic T-cell induction did not differ significantly between dendritic cells and macrophages. Separated CD4+ and CD8+ T-cell subsets contributed equally to lysis of infected targets. Experiments comparing wild-type M. bovis BCG strain with two new recombinant M. bovis BCG strains secreting listeriolysin revealed statistically significant higher maximal lysis values for recombinant M. bovis BCG. We conclude from our in vitro infection system with mycobacteria that dendritic cells are superior to macrophages in proliferative assays but equal to macrophages in their ability to induce cytolytic T-cell responses. Moreover, our data suggest that recombinant M. bovis BCG vaccine strains secreting listeriolysin improve cytolytic T-cell responses.

Antibodies, Monoclonal↗
PubMed1999

Comparative proteome analysis of Mycobacterium tuberculosis and Mycobacterium bovis BCG strains: towards functional genomics of microbial pathogens.

In 1993, the WHO declared tuberculosis a global emergency on the basis that there are 8 million new cases per year. The complete genome of the strain H37Rv of the causative microorganism, Mycobacterium tuberculosis, comprising 3924 genes has been sequenced. We compared the proteomes of two non-virulent vaccine strains of M. bovis BCG (Chicago and Copenhagen) with two virulent strains of M. tuberculosis (H37Rv and Erdman) to identify protein candidates of value for the development of vaccines, diagnostics and therapeutics. The mycobacterial strains were analysed by two-dimensional electrophoresis (2-DE) combining non-equilibrium pH gradient electrophoresis (NEPHGE) with SDS-PAGE. Distinct and characteristic proteins were identified by mass spectrometry and introduced into a dynamic 2-DE database (http://www.mpiib-berlin.mpg.de/2D-PAGE). Silver-stained 2-DE patterns of mycobacterial cell proteins or culture supernatants contained 1800 or 800 spots, respectively, from which 263 were identified. Of these, 54 belong to the culture supernatant. Sixteen and 25 proteins differing in intensity or position between M. tuberculosis H37Rv and Erdman, and H37Rv and M. bovis BCG Chicago, respectively, were identified and categorized into protein classes. It is to be hoped that the availability of the mycobacterial proteome will facilitate the design of novel measures for prevention and therapy of one of the great health threats, tuberculosis.

Bacterial Proteins↗
PubMed1999

Pneumocystis carinii pneumonia in mutant mice deficient in both TCRalphabeta and TCRgammadelta cells: cytokine and antibody responses.

Resistance to Pneumocystis carinii is achieved through cell-mediated and humoral immunity, but the interplay between these two systems in the immunocompetent host is not fully understood. TCRbetaxdelta-/- double-mutant mice deficient of all T cell populations naturally acquired P. carinii pneumonia with lethal consequences. Moribund mutants displayed numbers of pulmonary pathogens comparable to RAG-1-/- mice lacking all functional T and B lymphocytes. Pulmonary lavage cells of diseased TCRbetaxdelta-/- mutants secreted proinflammatory cytokines tumor necrosis factor-alpha, interleukin (IL)-12, and interferon-gamma, but not IL-4, -5, or -10. Serum immunoglobulin levels of both healthy and diseased mice were significantly reduced compared with immunocompetent animals. Secreted antibodies were mainly IgM, which also bound P. carinii. Mutants completely lacked IgG1, emphasizing strict T cell dependence of immunoglobulin switching to this isotype. Other IgG subclasses were strongly reduced and did not bind P. carinii. These results suggest that T cells are crucial for generation of antibodies against P. carinii relevant to resistance.

Animals↗
PubMed1999

Phenotypically activated gammadelta T lymphocytes in the peripheral blood of patients with tuberculosis.

Surface molecules with the potential relevance for resistance against Mycobacterium tuberculosis were investigated. The expression of lymphocyte function antigen-1, very late antigen (VLA)-4, l-selectin, intercellular adhesion molecule (ICAM)-1, major histocompatibility complex class II, Fas, and CD40 on alphabeta T cells, gammadelta T cells, NK cells, and monocytes of healthy donors and patients with tuberculosis were analyzed. A high activation status of gammadelta T cells and increased levels of soluble ICAM-1 in plasma of patients with tuberculosis versus healthy individuals was detected. Tuberculosis patients with and without an underlying systemic disease could be segregated by differential expression of VLA-4 and ICAM-1 on gammadelta T cells and on monocytes. The composition of peripheral blood mononuclear cells varied slightly, whereas the proportion of monocytes decreased significantly in patients with tuberculosis, compared with healthy controls. The activation phenotype of peripheral gammadelta T cells in patients with tuberculosis emphasizes the role of these T cells in controlling the inflammatory process during tuberculosis and perhaps other microbial infections.

Adolescent↗
PubMed1999

Live antigen carriers as tools for improved anti-tuberculosis vaccines.

Recombinant (r) Mycobacterium bovis BCG strains have been constructed which secrete biologically active listeriolysin (Hly) fusion protein of Listeria monocytogenes. In human and murine macrophage-like cell lines, intracellular persistence of these r-BCG strains was reduced as compared to the parental BCG strain. By immunogold labelling Hly was detected in membrane structures and within the phagosomal space of macrophages. Hly fusions consistently co-localized with a lysosome-associated membrane glycoprotein (LAMP-1) suggesting that membrane attack conformation of Hly was not altered. Although r-BCG microorganisms apparently did not egress into the cytoplasmic compartment of host cells, they both improved major histocompatibility complex class I presentation of co-phagocytosed soluble ovalbumin as compared with wild-type BCG microbes. These data suggest that Hly secretion endows BCG with an improved capacity to stimulate CD8 T cells. Because CD8 T cells play a major role in protection against tuberculosis such Hly-secreting r-BCG constructs are anti-tuberculosis vaccine candidates. In addition, we report on our r-Salmonella typhimurium expression system combined with the HlyB/HlyD/ TolC export machinery for delivering the prominent mycobacterial antigen Ag85B for immune recognition.

Animals↗
PubMed1999

Role of heat shock proteins in protection from and pathogenesis of infectious diseases.

Increased synthesis of heat shock proteins (hsp) occurs in prokaryotic and eukaryotic cells when they are exposed to stress. By increasing their hsp content, cells protect themselves from lethal assaults, primarily because hsp interfere with the uncontrolled protein unfolding that occurs under stress. However, hsp are not produced only by stressed cells; some hsp are synthesized constitutively and perform important housekeeping functions. Accordingly, hsp are involved in the assembly of molecules which play important roles in the immune system. It is not surprising that due to their wide distribution and their homology among different species, hsp represent target antigens of the immune response. Frequent confrontation of the immune system with conserved regions of hsp which are shared by various microbial pathogens can potentiate antimicrobial immunity. However, long-term confrontation of the immune system with hsp antigens which are similar in the host and invaders may convert the immune response against these host antigens and promote autoimmune disease. This review provides an overview of the role of hsp in immunity with a focus on infectious and autoimmune diseases.

Animals↗
PubMed1999

Soluble tumor necrosis factor alpha receptors in sera from leprosy patients.

Serum levels of soluble tumor necrosis factor alpha receptor I (sTNF-RI) were elevated in patients with lepromatous (LL) reactional-state type II leprosy, and sTNF-RII levels were increased in patients with full tuberculoid (TT) or LL type II leprosy. The sTNF-R in sera from patients with type II leprosy, but not other forms of leprosy, inhibited recombinant TNF cytolytic activities in vitro. This suggests that sTNF-R regulatory activities are partially impaired in patients with leprosy.

Adult↗
PubMed1999

Mammalian caspases: structure, activation, substrates, and functions during apoptosis.

Apoptosis is a genetically programmed, morphologically distinct form of cell death that can be triggered by a variety of physiological and pathological stimuli. Studies performed over the past 10 years have demonstrated that proteases play critical roles in initiation and execution of this process. The caspases, a family of cysteine-dependent aspartate-directed proteases, are prominent among the death proteases. Caspases are synthesized as relatively inactive zymogens that become activated by scaffold-mediated transactivation or by cleavage via upstream proteases in an intracellular cascade. Regulation of caspase activation and activity occurs at several different levels: (a) Zymogen gene transcription is regulated; (b) antiapoptotic members of the Bcl-2 family and other cellular polypeptides block proximity-induced activation of certain procaspases; and (c) certain cellular inhibitor of apoptosis proteins (cIAPs) can bind to and inhibit active caspases. Once activated, caspases cleave a variety of intracellular polypeptides, including major structural elements of the cytoplasm and nucleus, components of the DNA repair machinery, and a number of protein kinases. Collectively, these scissions disrupt survival pathways and disassemble important architectural components of the cell, contributing to the stereotypic morphological and biochemical changes that characterize apoptotic cell death.

Amino Acid Sequence↗
PubMed1999

Toxic bile salts induce rodent hepatocyte apoptosis via direct activation of Fas.

Cholestatic liver injury appears to result from the induction of hepatocyte apoptosis by toxic bile salts such as glycochenodeoxycholate (GCDC). Previous studies from this laboratory indicate that cathepsin B is a downstream effector protease during the hepatocyte apoptotic process. Because caspases can initiate apoptosis, the present studies were undertaken to determine the role of caspases in cathepsin B activation. Immunoblotting of GCDC-treated McNtcp.24 hepatoma cells demonstrated cleavage of poly(ADP-ribose) polymerase and lamin B1 to fragments that indicate activation of effector caspases. Transfection with CrmA, an inhibitor of caspase 8, prevented GCDC-induced cathepsin B activation and apoptosis. Consistent with these results, an increase in caspase 8-like activity was observed in GCDC-treated cells. Examination of the mechanism of GCDC-induced caspase 8 activation revealed that dominant-negative FADD inhibited apoptosis and that hepatocytes isolated from Fas-deficient lymphoproliferative mice were resistant to GCDC-induced apoptosis. After GCDC treatment, immunoprecipitation experiments demonstrated Fas oligomerization, and confocal microscopy demonstrated DeltaFADD-GFP (Fas-associated death domain-green fluorescent protein, aggregation in the absence of detectable Fas ligand mRNA. Collectively, these data suggest that GCDC-induced hepatocyte apoptosis involves ligand-independent oligomerization of Fas, recruitment of FADD, activation of caspase 8, and subsequent activation of effector proteases, including downstream caspases and cathepsin B.

Animals↗
PubMed1999

Hypercalcemia complicating leukemic transformation of agnogenic myeloid metaplasia-myelofibrosis.

Hypercalcemia is a common and potentially life-threatening metabolic derangement associated with many malignancies, especially solid tumors and multiple myeloma. Hypercalcemia has been reported only rarely with acute myelogenous leukemia. We describe a patient who developed hypercalcemia in association with transformation of agnogenic myeloid metaplasia into M7 acute myelogenous leukemia. Laboratory investigation revealed low levels of serum parathyroid hormone, undetectable levels of parathyroid hormone-related peptide, and normal levels of 25-hydroxyvitamin D. These observations suggest that another mediator was responsible for hypercalcemia in this patient. Awareness of this rare complication of acute myelogenous leukemia is essential for prompt diagnosis and management.

Cell Transformation, Neoplastic↗
PubMed1998

Early IL-4 induction in bone marrow lymphoid precursor cells by mycobacterial lipoarabinomannan.

IL-4 is produced promptly in response to certain infections and plays a key role in the Th1/Th2 T cell dichotomy; however, the cellular source remains a matter of debate. Here we describe the induction of IL-4 in bone marrow cells of normal and RAG-/- mice by both Mycobacterium tuberculosis and its major cell wall glycolipid, lipoarabinomannan. Characterization of the cell type responsible indicated that it was distinct from the NK1+ or CD4+ T cell previously ascribed the function of rapid IL-4 secretion. Cell-sorting experiments identified CD19+/B220+ precursor cells, presumably pre-B cells that produced IL-4 constitutively and whose frequency was rapidly and markedly up-regulated by lipoarabinomannan. Thus, pathogenic mycobacteria and their glycolipids may influence hemopoiesis by rapidly inducing IL-4 secretion in the bone marrow.

Animals↗
PubMed1998

Phosphorylated forms of activated caspases are present in cytosol from HL-60 cells during etoposide-induced apoptosis.

Treatment of HL-60 human leukemia cells with etoposide induces apoptotic cell death and activation of at least 18 electrophoretically distinct cysteine-dependent aspartate-directed protease (caspase) isoforms, several of which differ only in their isoelectric points. The purpose of the present study was to determine whether activated caspases are phosphorylated. Phosphatase treatment of cytosolic extracts containing active caspases followed by affinity labeling with N-(N-benzyloxycarbonylglutamyl-N-biotinyllysyl)aspartic acid [(2, 6-dimethylbenzoyl)oxy] methyl ketone (Z-EK(bio)D-aomk) showed a mobility shift in several of the labeled species, suggesting that phosphorylated forms of these enzymes are present in the extracts. Metabolic labeling with 32P followed by etoposide treatment and subsequent affinity purification of affinity-labeled caspases confirmed that at least three caspase species were phosphorylated. To detect effects of the phosphorylation on enzymatic activity, caspase-mediated cleavage of aspartylglutamylvalinylaspartyl-7-amino-4-trifluoromethylcoumarin (DEVD-AFC) and poly(ADP-ribose) polymerase (PARP) by phosphorylated and dephosphorylated extracts was measured. No significant changes in Km or vmax were detected using DEVD-AFC. In contrast, a slight, but significant enhancement of PARP cleavage was observed in dephosphorylated extracts, suggesting that phosphorylation of active caspases could have an inhibitory effect on enzyme activity. These observations, which provide the first evidence that caspases are phosphoproteins, suggest that caspases may be targets for some of the growing list of protein kinases that are involved in apoptotic events.

Apoptosis↗