-
C Goyvaerts,
K De Groeve,
J Dingemans,
S Van Lint,
L Robays,
C Heirman,
J Reiser,
X-Y Zhang,
K Thielemans, P De Baetselier,
G Raes,
K Breckpot
[show abstract]
[hide abstract]
ABSTRACT: Lentiviral vectors (LVs) provide unique opportunities for the development of immunotherapeutic strategies, as they transduce a variety of cells in situ, including antigen-presenting cells (APCs). Engineering LVs to specifically transduce APCs is required to promote their translation towards the clinic. We report on the Nanobody (Nb) display technology to target LVs to dendritic cells (DCs) and macrophages. This innovative approach exploits the budding mechanism of LVs to incorporate an APC-specific Nb and a binding-defective, fusion-competent form of VSV.G in the viral envelope. In addition to production of high titer LVs, we demonstrated selective, Nb-dependent transduction of mouse DCs and macrophages both in vitro and in situ. Moreover, this strategy was translated to a human model in which selective transduction of in vitro generated or lymph node (LN)-derived DCs and macrophages, was demonstrated. In conclusion, the Nb display technology is an attractive approach to generate LVs targeted to specific cell types.Gene Therapy advance online publication, 12 January 2012; doi:10.1038/gt.2011.206.
Gene therapy 01/2012; · 4.75 Impact Factor
-
G Caljon,
V Caveliers,
T Lahoutte,
B Stijlemans,
G H Ghassabeh,
J Van Den Abbeele,
I Smolders, P De Baetselier,
Y Michotte,
S Muyldermans,
S Magez,
R Clinckers
[show abstract]
[hide abstract]
ABSTRACT: Nanobodies are promising antigen-binding moieties for molecular imaging and therapeutic purposes because of their favourable pharmacological and pharmacokinetic properties. However, the capability of monovalent nanobodies to reach targets in the CNS remains to be demonstrated.
We have assessed the blood-brain barrier permeability of Nb_An33, a nanobody against the Trypanosoma brucei brucei variant-specific surface glycoprotein (VSG). This analysis was performed in healthy rats and in rats that were in the encephalitic stage of African trypanosomiasis using intracerebral microdialysis, single photon emission computed tomography (SPECT) or a combination of both methodologies. This enabled the quantification of unlabelled and (99m) Tc-labelled nanobodies using, respectively, a sensitive VSG-based nanobody-detection elisa, radioactivity measurement in collected microdialysates and SPECT image analysis.
The combined read-out methodologies showed that Nb_An33 was detected in the brain of healthy rats following i.v. injection, inflammation-induced damage to the blood-brain barrier, as in the late encephalitic stage of trypanosomiasis, significantly increased the efficiency of passage of the nanobody through this barrier. Complementing SPECT analyses with intracerebral microdialysis improved analysis of brain disposition. There is clear value in assessing penetration of the blood-brain barrier by monovalent nanobodies in models of CNS inflammation. Our data also suggest that rapid clearance from blood might hamper efficient targeting of specific nanobodies to the CNS.
Nanobodies can enter the brain parenchyma from the systemic circulation, especially in pathological conditions where the blood-brain barrier integrity is compromised.
British Journal of Pharmacology 10/2011; 165(7):2341-53. · 4.41 Impact Factor
-
S Muyldermans,
T N Baral,
V Cortez Retamozzo, P De Baetselier,
E De Genst,
J Kinne,
H Leonhardt,
S Magez,
V K Nguyen,
H Revets,
U Rothbauer,
B Stijlemans,
S Tillib,
U Wernery,
L Wyns,
Gh Hassanzadeh-Ghassabeh,
D Saerens
[show abstract]
[hide abstract]
ABSTRACT: It is well established that all camelids have unique antibodies circulating in their blood. Unlike antibodies from other species, these special antibodies are devoid of light chains and are composed of a heavy-chain homodimer. These so-called heavy-chain antibodies (HCAbs) are expressed after a V-D-J rearrangement and require dedicated constant gamma-genes. An immune response is raised in these so-called heavy-chain antibodies following classical immunization protocols. These HCAbs are easily purified from serum, and the antigen-binding fragment interacts with parts of the target that are less antigenic to conventional antibodies. Since the antigen-binding site of the dromedary HCAb is comprised in one single domain, referred to as variable domain of heavy chain of HCAb (VHH) or nanobody (Nb), we designed a strategy to clone the Nb repertoire of an immunized dromedary and to select the Nbs with specificity for our target antigens. The monoclonal Nbs are well produced in bacteria, are very stable and highly soluble, and bind their cognate antigen with high affinity and specificity. We have successfully developed recombinant Nbs for research purposes, as probe in biosensors, to diagnose infections, and to treat diseases like cancer or trypanosomosis.
Veterinary Immunology and Immunopathology 11/2008; 128(1-3):178-83. · 2.08 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: The epidermal growth factor receptor (EGFR) is frequently overexpressed in various tumours of epidermal origin and is held responsible for tumourigenicity and tumour persistence. Increased nuclear factor (NF)-kappaB activity has been suggested to be involved in the malignant behaviour of EGFR-overexpressing cells. However, the mechanisms that regulate EGF-induced NF-kappaB activation are still largely unknown. Here we show that EGF can induce NF-kappaB-dependent gene expression independently from IkappaBalpha degradation or p100 processing in EGFR-overexpressing HEK293T cells. Moreover, EGF-induced NF-kappaB activation could be inhibited by overexpression of ABINs, which were previously identified as intracellular inhibitors of tumour necrosis factor, interleukin-1 and lipopolysaccharide-induced NF-kappaB activation. Knockdown of ABIN-1 by RNA interference boosted the NF-kappaB response upon EGF stimulation. The C-terminal ubiquitin-binding domain containing region of ABINs was crucial and sufficient for NF-kappaB inhibition. Adenoviral gene transfer of ABINs reduced constitutive NF-kappaB activity as well as the proliferation of EGFR-overexpressing A431 and DU145 human carcinoma cells. Altogether, these results demonstrate an important role for an ABIN-sensitive non-classical NF-kappaB signalling pathway in the proliferation of EGFR-overexpressing tumour cells, and indicate a potential use for ABIN gene therapy in the treatment of cancer.
Oncogene 08/2008; 27(47):6131-40. · 6.37 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: It is generally accepted that the action of cytokines results from their binding to specific receptors. However, many cytokines possess lectin-like activity that may be essential for the expression of their full biological activities. This review focuses on the physiological relevance of the lectin-like activity of cytokines during the innate immune response in mammals, using TNF as an illustrative example. Moreover, we will show that TNF displays functional analogies with a defense molecule from the earthworm Eisenia foetida termed CCF. These analogies are not reflected by primary sequence homology between CCF and TNF but are particularly based on a similar lectin-like activity/domain. Hence, from a phylogenetic point of view, the lectin-like activity/domain of CCF and TNF may represent an essential recognition mechanism that has been functionally conserved during the innate immune response of invertebrates and vertebrates as a result of convergent evolution.
Progress in molecular and subcellular biology 02/2004; 34:145-63.
-
[show abstract]
[hide abstract]
ABSTRACT: Trypanosome infections are marked by severe pathological features, including anemia, splenomegaly, and suppression of T-cell proliferation. We have used lymphotoxin-alpha-deficient (LT-alpha(-/-)) mice, as well as LT-alpha-tumor necrosis factor-double-deficient (LT-alpha(-/-) TNF(-/-)) mice, to analyze the contributions of these related cytokines in both induction of trypanosomosis-associated immunopathology and infection control. Moreover, as the cytokine-deficient mice used have no detectable lymph nodes and lack germinal-center formation upon immune stimulation, we have analyzed the functional importance of both the lymph nodes and spleen during experimental Trypanosoma brucei infections. First, we show that the absence of LT-alpha does not significantly alter early trypanosomosis development or pathology but does result in better control of late-stage parasitemia levels and slightly prolonged survival. This increased survival of infected LT-alpha(-/-) mice coincides with the appearance of increased chronic-stage anti-trypanosome immunoglobulin M (IgM)-IgG2a serum titers that are generated in the absence of functional peripheral lymphoid tissue and do not require germinal-center formation. Second, we show that splenectomized mice control their parasitemia to the same extent as fully immune-competent littermates. Finally, using LT-alpha(-/-) TNF(-/-) double-deficient mice, we show that in these mice T. brucei infections are very well controlled during the chronic infection stage and that infection-induced pathology is minimized. Together, these findings indicate that while increased IgM-IgG2a anti-trypanosome antibody titers (generated in the absence of LT-alpha, peripheral lymph nodes, and germinal-center formation) coincide with improved parasitemia control, it is TNF that has a major impact on trypanosomosis-associated immunopathology.
Infection and Immunity 04/2002; 70(3):1342-51. · 4.16 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Coelomic fluid of Eisenia foetida earthworms (Oligochaeta, Annelida) contains a 42-kDa defense molecule named CCF for coelomic cytolytic factor. By binding microbial antigens, namely the O-antigen of lipopolysaccharide (LPS), beta-1,3-glucans, or N,N'-diacetylchitobiose present, respectively, on Gram-negative bacteria or yeast cell walls, CCF triggers the prophenoloxidase activating pathway. We report that CCF recognizes lysozyme-predigested Gram-positive bacteria or the peptidoglycan constituent muramyl dipeptide as well as muramic acid. To identify the pattern recognition domains of CCF, deletion mutants were tested for their ability to reconstitute the prophenoloxidase cascade in E. foetida coelomic fluid depleted of endogenous CCF in the presence of LPS, beta-1,3-glucans, N,N'-diacetylchitobiose, and muramic acid. In addition, affinity chromatography of CCF peptides was performed on immobilized beta-1,3-glucans or N,N'-diacetylchitobiose. We found that the broad specificity of CCF for pathogen-associated molecular patterns results from the presence of two distinct pattern recognition domains. One domain, which shows homology with the polysaccharide and glucanase motifs of beta-1,3-glucanases and invertebrate defense molecules located in the central part of the CCF polypeptide chain, interacts with LPS and beta-1,3-glucans. The C-terminal tryptophan-rich domain mediates interactions of CCF with N,N'-diacetylchitobiose and muramic acid. These data provide evidence for the presence of spatially distinct carbohydrate recognition domains within this invertebrate defense molecule.
Journal of Biological Chemistry 01/2002; 276(49):45840-7. · 4.77 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Trypanosomes use antigenic variation of their variant-specific surface glycoprotein (VSG) coat as defense against the host immune system. However, in order to sustain their growth, they need to expose conserved epitopes, allowing host macromolecule binding and receptor-mediated endocytosis. Here we show that Trypanosoma brucei uses the conserved chitobiose-oligomannose (GlcNAc(2)-Man(5-9)) moieties of its VSG as a binding ligand for tumor necrosis factor (TNF), a host cytokine with lectin-like properties. As endocytosis in trypanosomes is restricted to the flagellar pocket, we show that soluble flagellar pocket extracts, and in particular soluble VSG, inhibit the binding of (125)I-TNF to trypanosomes. The interaction between TNF and VSG is confirmed by affinity chromatography, biosensor, and dot-blot affinity measurements, and soluble VSG inhibition of TNF-mediated trypanolysis. In all approaches, removal of N-linked carbohydrates abrogates the TNF-VSG interaction. In addition, synthetic high mannose oligosaccharides can block TNF-VSG interactions, and a VSG glycopeptide carrying the GlcNAc(2)-Man(5-9) moiety is shown to inhibit TNF-mediated trypanosome killing in mixed parasite/macrophage cell cultures. Together, these results support the observation that TNF plays a role in growth control of trypanosomes and, moreover, suggest that, by the use of conserved VSG carbohydrates as lectin-binding epitopes, trypanosomes can limit the necessity to express large numbers of invariant surface exposed receptors.
Journal of Biological Chemistry 10/2001; 276(36):33458-64. · 4.77 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Resistance to Trypanosoma brucei brucei has been correlated with the ability of infected animals to produce interferon (IFN)-gamma and tumor necrosis factor (TNF) in an early phase of infection, followed by interleukin (IL)-4 and IL-10 in late and chronic stages of the disease. Contributions of IFN-gamma and IL-10 in the control of parasitemia and survival of mice infected with T. brucei brucei were investigated by using IFN-gamma(-/-) and IL-10(-/-) mice. Results suggest that IFN-gamma, mainly secreted by CD8(+) T cells, is essential for parasite control via macrophage activation, which results in TNF and nitric oxide secretions. IL-10, partially secreted by CD4(+) T cells, seems to be important for the survival of infected mice. Its absence resulted in the sustained secretion of inflammatory mediators, which indicated the role of IL-10 in maintaining the balance between pathogenic and protective immune responses during African trypanosomosis.
The Journal of Infectious Diseases 07/2001; 183(12):1794-800. · 6.41 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Based on the assumption that invertebrates, like vertebrates, possess factors regulating responses to infection or wounding, studies dealing with the evolution of immunity have focussed on the isolation and characterisation of putative cytokine-related molecules from invertebrates. Until recently, most of our knowledge of cytokine- and cytokine receptor-like molecules in invertebrates relies on functional assays and similarities at the physicochemical level. As such, a phylogenetic relationship between invertebrate cytokine-like molecules and vertebrate counterparts could not be convincingly demonstrated. Recent genomic sequence analyses of interleukin-1-receptor-related molecules, that is Toll-like receptors, and members of the transforming growth factor-beta superfamily suggest that the innate immune system of invertebrates and vertebrates evolved independently. In addition, data from protochordates and annelids suggest that invertebrate cytokine-like molecules and vertebrate factors do not have the same evolutionary origin. We propose instead that the convergence of function of invertebrate cytokine-like molecules and vertebrate counterparts involved in innate immune defences may be based on similar lectin-like activities.
Cellular and Molecular Life Sciences CMLS 06/2001; 58(5-6):801-14. · 6.57 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Despite the wide clinical use of glucocorticoids in the chemotherapy of leukaemia and lymphoma, there have been limited efforts at understanding the effects of these hormones on metastasis formation. The purpose of this study was to investigate the effects of glucocorticoids on the tissue-infiltrating capability of lymphoid cells. Using an in vitro invasion assay, we found that dexamethasone, a synthetic glucocorticoid analogue, inhibited the invasion of a murine T-cell hybridoma through a monolayer of fibroblast-like cells. Even low doses of dexamethasone were effective at inhibiting cellular transmigration (EC50 = 0.4 nM). A maximal decrease was observed after an overnight culture in the presence of dexamethasone. The effect persisted for at least 24 h after removal of the drug and required the binding of the hormone to its intracellular glucocorticoid receptor. Our results suggest that the decreased invasiveness of dexamethasone-treated cells is not the consequence of reduced motility or deficient production of an autocrine factor required for cell migration. This in vitro study suggests that glucocorticoids may act to reduce dissemination of lymphoma cells in vivo.
International Immunopharmacology 05/2001; 1(4):785-93. · 2.38 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: The type I/type II cytokine balance may influence the development of different subsets of suppressive macrophages, i.e., classically activated macrophages (caMphi, type I) versus alternatively activated macrophages (aaMphi, type II). Recently, we showed that although mice infected with phospholipase C-deficient (PLC-/-) Trypanosoma brucei brucei exhibit a clear shift from type I to the type II cytokine production, wild type (WT)-infected mice remain locked in a type I cytokine response. In the present study, phenotype and accessory cell function of macrophages elicited during WT and PLC-/- T. b. brucei infection were compared. Results indicate that caMphi develop in a type I cytokine environment in the early phase of WT and PLC-/- trypanosome infection, correlating with inhibition of T cell activation triggered by a mitogen, a superantigen, or an antigen. In the late stage of infection, only PLC(-/-)-infected mice resisting the infection develop type II cytokine-associated aaMphi correlating with impaired antigen- but not mitogen- or superantigen-induced T cell activation.
Journal of Leukocyte Biology 04/2001; 69(3):387-96. · 4.99 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: In this study, we characterised the anti-tumour as well as the pro-metastatic activities of TNF mutants deficient in their lectin-like activity.1619 We report that, despite reduced systemic toxicity as compared to wild-type (wt) mTNF, a (T104A) and a (T104A-E106A-E109A) mTNF mutant (triple mTNF) retained most of their necrotic and tumouristatic activities, as measured in a CFS-1 fibrosarcoma and a B16BL6 melanoma tumour model, respectively. These mutants also conserved their anti-angiogenic activity, as measured in an in vitro endothelial morphogenesis assay.26 In contrast, the pro-metastatic activity of the T104A and the triple mTNF mutants in the CFS-1 fibrosarcoma and the 3LL-R Lewis lung carcinoma tumour model was significantly lower than that of the wt molecule. These results thus indicate that the lectin-like domain of TNF is not implicated in its necrotic, tumouristatic and anti-angiogenic activities, but that it can contribute to the pro-metastatic effect of the cytokine. In conclusion, in view of their reduced systemic toxicity and pro-metastatic capacity, but their retained anti-tumour activities, lectin-deficient TNF mutants might prove to be therapeutically interesting alternatives to wt TNF.
International Journal of Cancer 03/2001; 91(4):543-9. · 5.44 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: We previously reported on a murine T lymphoma cell line, BW-Sp3, with inherent immunogenicity. BW-Sp3 tumors can elicit an anti-tumor CD8(+) CTL response capable of mediating a regression of subcutaneous tumors. However, this immune response is inadequate to eliminate cancer cells completely in a significant percentage of the recipients, resulting in progressing tumors. In this tumor model, tumor progression correlated with a tolerization of tumor-reactive T cells and cellular immunotherapy of tumor bearing animals, with or without B7-mediated costimulation, even increased tumor progression (Raes et al, 1998). In the present study, we investigated whether the co-expression of IFN gamma, together with B7-1, could have beneficial effects on immunotherapy. Although immunotherapy with IFN gamma and B7-1 single transfectants tended to tolerize anti-tumor T-cells and consequently increased tumor growth, the B7-1/IFN gamma double transfectants resulted in a more beneficial outcome. This phenomenon correlated with an increased CTL-inducing potential of the double transfectants. Secondly, we wondered whether CTLA-4 signalling was involved in the down-regulation of the anti-tumor response. Indeed, when immunotherapy was provided along with anti-CTLA-4, the protection by B71/IFN gamma double transfectants was further improved and the tumor-promoting effect of BW-Sp3(B7-1) was compensated for. Our results indicate that B7-1, IFN gamma and the blockade of CTLA-4 cooperate to tilt the balance in favour of tumor elimination, while either factor alone fails to do so or even promotes tumor growth.
International Journal of Cancer 09/2000; 87(4):539-47. · 5.44 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: During African trypanosomiasis, macrophages play a central role in T cell hyporesponsiveness to parasite-related and unrelated antigens. In this study, the ability of macrophages from Trypanosoma b. brucei-infected mice to present exogenous antigens to a major histocompatibility complex (MHC) class II-restricted CD4+ T cell hybridoma was analysed. We demonstrate that the antigen presentation capacity of macrophages from infected mice is markedly reduced as a result of a lower expression of [MHC class II-peptide] complexes on their plasma membrane. This defect did not result from a decreased antigen uptake/catabolism, a reduced MHC class II and intercellular adhesion molecule 1 expression on the surface of macrophages, a decreased affinity of MHC class II molecules for antigenic peptides, a competition between exogenous and parasite antigens, or the generation of inhibitory peptides. Our data indicate that the step resulting in coexpression of processed antigens and MHC class II molecules is affected in T. b. brucei-infected mice. Additionally, macrophages from infected mice secreted IL-10 that in turn contributes to the impairment of T cell activation.
Parasite Immunology 08/2000; 22(7):361-70. · 2.60 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Mechanisms regulating resistance to African trypanosomes were addressed by comparing the immune responses of mice infected with attenuated Trypanosoma brucei brucei lacking the phospholipase C gene (PLC-/-) and those of mice infected with wild-type (WT) parasites. Inhibition of concanavalin A (ConA)-induced T cell proliferation occurred in spleen and lymph nodes of PLC-/-- and WT-infected mice. Although suppressive cells were elicited in spleen and lymph nodes of WT-infected animals, such cells were not detected in lymph nodes of PLC-/--infected mice. PLC-/--infected mice had more interleukin-4 and -10 in their blood than did WT-infected mice. Correspondingly, PLC-/--infected mice had higher IgG1 antibody levels against variant surface glycoprotein than did WT-infected mice. These data indicate that attenuation of T. b. brucei correlates with the absence of cells suppressing ConA-induced T cell proliferation in the lymph nodes, with increased production of Th2 cytokines and a stronger IgG1 antibody response to trypanosome antigens.
The Journal of Infectious Diseases 04/2000; 181(3):1110-20. · 6.41 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Discrimination of self and nonself is one of the features of all animal species but the ways of elimination of nonself are different. Defense strategies of invertebrates, which lack antibodies and lymphocytes, are based on innate defense mechanisms. The study of such, undoubtedly less complex, defense mechanisms in invertebrates may shed a new light on the more sophisticated immunity of vertebrates. The main aim of this review is to show on one experimental model--an oligochaete annelid--cellular and humoral defense pathways protecting against microbial infection.
Folia Microbiologica 02/2000; 45(4):283-300. · 0.68 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: To better understand the role of tumor necrosis factor (TNF) during Trypanosoma cruzi infection in BALB/c mice, we have investigated the kinetics of circulating tumor necrosis factor (TNF), soluble TNF receptor 1 (sTNR1), and sTNFR2 levels, as well as the interactions between such factors, in relation to parasitemia, cachexia, and mortality of acutely infected animals. Our data show that the parasitemic phase of T. cruzi infection in mice is associated with high levels of circulating TNF and sTNFR2, resulting in the formation of cytokine-receptor complexes and some degree of neutralization of TNF bioactivity. Although sTNR2 levels always exceeded TNF levels, low sTNFR/TNF circulating ratios were associated with cachexia in all infected mice, whereas the lowest ratios were observed in dying animals harboring the highest parasitemia. We also studied the modulation of sTNFR/TNF ratios induced by anti-TNF antibodies administered to infected animals and their consequences on the outcome of the infection. The injection of anti-TNF monoclonal antibody (MAb) TN3 into infected mice resulted in a paradoxical overproduction of TNF (associated with a higher parasitemia), lowered the sTNFR/TNF circulating ratios, and considerably worsened cachexia and mortality of animals. Another anti-TNF MAb (1F3F3) decreased the in vivo availability of TNF as well as parasite levels and reduced cachexia. Altogether, such results highlight that, besides playing a beneficial role early in infection, TNF also triggers harmful effects in the parasitemic phase, which are limited by the in vivo simultaneous endogenous production of soluble receptors.
Infection and Immunity 12/1999; 67(11):5579-86. · 4.16 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Infection-associated immunoincompetence during malaria might result from macrophage dysfunction. In the present study, we investigated the role of macrophages as target for immunosuppression during infection, using the murine Plasmodium c. chabaudi model. Special attention has been paid to the analysis of processing/presentation of protein antigens and presentation of peptides, using cocultures of peritoneal exudate cells (PECs) from infected mice and antigen-specific T-cell hybridomas. The results obtained indicate a defective processing of protein antigens that becomes maximal at acute parasitemias. In addition, macrophages from acutely infected mice suppress the interleukin-2 production by the antigen-activated T-cell hybridomas. This effect was independent of prostaglandin and nitric oxide production by the macrophage. The possible role of parasite components in the impaired accessory cell function of PECs was investigated and hemozoin, the end-product of the hemoglobin catabolism by intraerythrocytic malaria parasites, was found to induce similar infection-associated deficiencies in vitro. Moreover, hemozoin, was shown to mimic the immunosuppressive effects induced in PECs during in-vivo infections with P. chabaudi. In conclusion, we propose that hemozoin is a key factor in the malaria-associated immunosuppression, affecting both the antigen processing and immunomodulatory functions of macrophages.
Parasite Immunology 12/1999; 21(11):545-54. · 2.60 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Tumor necrosis factor TNF can trigger increases in membrane conductance of mammalian cells in a receptor-independent manner via its lectin-like domain. A lectin-deficient TNF mutant, lacking this activity, was able to bind to artificial liposomes in a pH-dependent manner, but not to insert into the bilayer, just like wild type TNF. A peptide mimicking the lectin-like domain, which can still trigger increases in membrane currents in cells, failed to interact with liposomes. Thus, the capacity of TNF to trigger increases in membrane conductance in mammalian cells does not correlate with its ability to interact with membranes, suggesting that the cytokine does not form channels itself, but rather interacts with endogenous ion channels or with plasma membrane proteins that are coupled to ion channels.
FEBS Letters 11/1999; 460(1):107-11. · 3.54 Impact Factor
