OpenUCT :: Browsing by Author "Ryffel, Bernhard"

Browsing by Author "Ryffel, Bernhard"

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Open Access
A study of the immune response in murine experimental malaria, with special reference to the effects of South African medicinal plants, artesunate and chloroquine
(2003) Gumede, Bonginkosi; Folb, Peter; Ryffel, Bernhard
The role of pro-inflarrnnatory cytokines (TNF and IFN-y) in a murine experimental malaria model for cerebral malaria is reported in this thesis. Wild type and receptor knockout mice (IFN-y deficient mice (IFN-l") and TNF-a/fr1- double deficient) were infected with Plasmodium berghei ANKA {PbA). PbA induced fatal cerebral malaria in wild type mice, which died within 5 to 8 days. In contrast, IFN-f1- and TNF-a/[r1-were completely resistant to PbA-induced cerebral malaria. Both wild type and mutant mice developed a similar degree of parasitaemia in the initial phase, and anaemia and leukocytosis were not different, showing that both anaemia and mobilisation of leukocytes occur in the absence of TNF and IFN-y. The results show that TNF'- and IFN,f'- mice are resistant to PbA-induced cerebral malaria, and confirm the role played by Thl cytokines in its pathogenesis. Plasmodium chabaudi chabaudi AS infection results in splenomegaly, and activation of the immune system. Resistant C57BL/6 mice, which eliminate the parasites and survive the infection, developed marked splenomegaly. Susceptible A/J mice develop minimal splenomegaly. In this work it has been shown that there is a rapid deterioration in splenic architecture, although immunohistochemistry confirmed preservation of a high level of structure and organisation. CD 11 c {dendritic) cells moved from the marginal zone into the CD4+ T cell area (where their antigen presenting function would be maximal). The juxtaposition of CDllc and T cells might be associated with immune complex formation in the spleen during the infection. The findings were similar for C57BL/6 and A/J mice. A 14-day course of artesunate 100 mg/kg prevented completely the development of parasitaemia and cerebral malaria in Plasmodium berghei ANKA infected mice, with survival of more than 60d. Chloroquine enhanced production of IL-10. Artesunate displayed enhanced IL-1 0 activity but no effect on production of pro-inflammatory cytokines. Extracts of W. salutaris, a South African medicinal plant, reduced parasitaemia by >50% at doses of 100 and 500mg/kg, and of A. annua reduced parasitaemia by 64% at a dose of 200 mg/kg. These extracts, and extracts of H. procumbens, had immunomodulatory activity on TNF-a., IFN-y, IL-12 and IL-10 production by Con A- and LPS-induced splenocytes.
Open Access
The anti-Pseudomonas aeruginosa antibody Panobacumab is efficacious on acute pneumonia in neutropenic mice and has additive effects with meropenem
(Public Library of Science, 2013) Secher, Thomas; Fas, Stefanie; Fauconnier, Louis; Mathieu, Marieke; Rutschi, Oliver; Ryffel, Bernhard; Rudolf, Michael
Pseudomonas aeruginosa ( P. aeruginosa ) infections are associated with considerable morbidity and mortality in immunocompromised patients due to antibiotic resistance. Therefore, we investigated the efficacy of the anti- P. aeruginosa serotype O11 lipopolysaccharide monoclonal antibody Panobacumab in a clinically relevant murine model of neutropenia induced by cyclophosphamide and in combination with meropenem in susceptible and meropenem resistant P. aeruginosa induced pneumonia. We observed that P. aeruginosa induced pneumonia was dramatically increased in neutropenic mice compared to immunocompetent mice. First, Panobacumab significantly reduced lung inflammation and enhanced bacterial clearance from the lung of neutropenic host. Secondly, combination of Panobacumab and meropenem had an additive effect. Third, Panobacumab retained activity on a meropenem resistant P. aeruginosa strain. In conclusion, the present data established that Panobacumab contributes to the clearance of P. aeruginosa in neutropenic hosts as well as in combination with antibiotics in immunocompetent hosts. This suggests beneficial effects of co-treatment even in immunocompromised individuals, suffering most of the morbidity and mortality of P. aeruginosa infections.
Open Access
Fatal Mycobacterium tuberculosis infection despite adaptive immune response in the absence of MyD88
(2004) Fremond, Cecile M; Yeremeev, Vladimir; Nicolle, Delphine M; Jacobs, Muazzam; Quesniaux,Valerie F; Ryffel, Bernhard
Toll-like receptors (TLRs) such as TLR2 and TLR4 have been implicated in host response to mycobacterial infection. Here, mice deficient in the TLR adaptor molecule myeloid differentiation factor 88 (MyD88) were infected with Mycobacterium tuberculosis (MTB). While primary MyD88–/– macrophages and DCs are defective in TNF, IL-12, and NO production in response to mycobacterial stimulation, the upregulation of costimulatory molecules CD40 and CD86 is unaffected. Aerogenic infection of MyD88–/– mice with MTB is lethal within 4 weeks with 2 log10 higher CFU in the lung; high pulmonary levels of cytokines and chemokines; and acute, necrotic pneumonia, despite a normal T cell response with IFN-γ production to mycobacterial antigens upon ex vivo restimulation. Vaccination with Mycobacterium bovis bacillus Calmette-Guérin conferred a substantial protection in MyD88–/– mice from acute MTB infection. These data demonstrate that MyD88 signaling is dispensable to raise an acquired immune response to MTB. Nonetheless, this acquired immune response is not sufficient to compensate for the profound innate immune defect and the inability of MyD88–/– mice to control MTB infection.
Open Access
IL-33-mediated protection against experimental cerebral malaria is linked to induction of Type 2 innate lymphoid cells, M2 macrophages and regulatory T cells
(Public Library of Science, 2015) Besnard, Anne-Gaelle; Guabiraba, Rodrigo; Niedbala, Wanda; Palomo, Jennifer; Reverchon, Flora; Shaw, Tovah N; Couper, Kevin N; Ryffel, Bernhard; Liew, Foo Y
Author Summary Cerebral malaria (CM) caused by the parasite Plasmodium sp . is a fatal disease, especially in children. Currently there is no effective treatment. We report here our investigation on the role of a recently discovered cytokine IL-33, in treating experimental cerebral malaria (ECM) in the susceptible C57BL/6 mice. IL-33 protects the mice against ECM. The protection is accompanied by a reduction of Th1 response and the enhancement of type 2 cytokine response. We also found that IL-33 mediates its protective effect by inducing a population of type 2 innate lymphoid cells (ILC2), which then polarize macrophages to alternatively-activated phenotypes (M2). M2 in turn expand regulatory T cells (Tregs) which suppress the deleterious Th1 response. Our report therefore reveals hitherto unrecognised mechanisms of the regulation of ECM and provide a novel function of IL-33.
Open Access
In vivo effects of South African traditional medicines against Mycobacterium tuberculosis in experimental mice
(2001) Bapela, Nchinya Benedict; Ryffel, Bernhard; Smith, Peter J
Although it is more than 100 years since Robert Koch discovered the tubercle bacillus, and more than 40 years since effective chemotherapy became available, the incidence of tuberculosis is increasing in much of the developing world and has recently re-emerged as a public health problem in industrialized countries. This problem is compounded by the increase in host susceptibility to tuberculosis caused by co-infection with HIV (Human Immunodeficiency Virus) and the emergence of Mycobacterium tuberculosis strains that are resistant to the front-line drugs. These factors highlight the urgent need for development of new drug classes to counter the threat posed by tuberculosis. The purpose of the present study was to develop a mouse model for Mycobacterium tuberculosis with the aim of determining the antimycobacterial activity of medicinal plants used by traditional doctors to treat tuberculosis in South Africa. Furthermore, the toxic effects of these medicinal plants in uninfected mice were determined. A field trip to the Northern Cape, Western Cape, Eastern Cape and Free State provinces was undertaken and medicinal plants used by traditional doctors to treat tuberculosis or its symptoms were collected, identified and examined for their therapeutic effects against Mycobacterium tuberculosis, determined using the mouse model. In addition, the effects of medicinal plants on the production of cytokines and granuloma formation in infected mice were examined. Six-to-ten week old C57BL/6 mice were infected with 107 viable Mycobacterium tuberculosis H37Rv strain by an aerosol exposure model. Bacterial growth was monitored by sacrificing infected but untreated mice at day 1, week 2 and week 4. Treatment with medicinal plant extracts was started 2 weeks after infection and continued for 2 weeks. An INH-RIF combination was used as positive controls. The bacterial load in infected but untreated mice increased by 1 log unit each week for 2 to 3 weeks. Bacterial loads were not detected in INH-RIF treated mice after 2 weeks of treatment. Treatment of mice with high doses of plant extracts was toxic. None of the tested medicinal plant extracts showed any activity against Mycobacterium tuberculosis. The production of IL-12 at week 4 was suppressed/ decreased when plant extract A was given at different concentrations. The bacterial loads in the lungs of the plant extract A treated mice was higher than that of the untreated mice (p < 0.005). Histological analysis of the lungs also revealed a high number of bacilli and increased size of the formed granuloma. In conclusion, the selected plant extracts obtained by water extraction exhibited no anti-tuberculosis activity in the laboratory mouse model for Mycobacterium tuberculosis infection. Furthermore, it was also shown that some plant extracts suppressed the production of IL-12, which plays an important role in the host's defense against Mycobacterium tuberculosis. However, further work is required to test if treatment for longer periods exhibits antituberculous activity.
Open Access
Investigations of cellular immune mechanisms to malaria during pregnancy in a malaria holoendemic region of Western Kenya
(2003) Othoro, Caroline; Ryffel, Bernhard
Women during pregnancy in holoendemic regions of malaria are at an increased risk for peripheral malaria infections with potential for developing placental malaria. The immunological basis of protection and pathogenesis are incompletely understood. This thesis investigates both processes. Research on maternal placental immune responses necessitates the collection of reliable placental intervillous blood; an appropriate method for placental blood collection was therefore ﬁrst determined. Five documented methods of collection (perfusion, incision, biopsy, tissue grinding and prick) were compared for foetal blood contamination and mononuclear cell profiles using ﬂow cytometry. Placental blood collection by prick was established as the most appropriate method and was subsequently used for further immunological investigations.
Open Access
Involvement of endothelial cells and macrophages in mycobacterial infections
(2002) Nkhahle, Senate; Ryffel, Bernhard; Mpagi, Joseph
Tuberculosis remains to be a leading infectious cause of death worldwide. This is in spite of the BCG vaccine against tuberculosis that has been in use for over 80 years as well as several chemotherapies. Mycobacterium tuberculosis, the causative agent of tuberculosis, is a facultative intracellular pathogen targeting host cells, predominantly macrophages, to establish an infection. Endothelial cells form a barrier that has to be crossed by the bacilli in the establishment, and subsequent dissemination of mycobacterial infection. The present study was undertaken to investigate the phagocytosis of mycobacteria by endothelial cells and macrophages and the subsequent activation of these host cells after infection with the bacilli. Endothelial cells, obtained from the human umbilical vein (HUVEC) were infected with BCG-GFP under various conditions and uptake determined by means of ﬂow cytometry. Endothelial cells phagocytised mycobacteria in a dose- and a time-dependant manner. Exposure of mycobacteria to serum opsonins enhanced the uptake of the bacilli by endothelial cells. However, heat killing of mycobacteria inhibited its uptake by endothelial cells. Data from the fluorescent microscope showed the association of BCG-GFP signal with endothelial cells detected on the FACS caliber. Analysis by confocal microscopy conﬁrmed internalisation of endothelial cells by mycobacteria. Endothelial cells were further investigated for an acquired phenotype following infection with mycobacteria. CD31, a marker for endothelial cells, was neither down regulated nor up regulated. However, ICAM-1 expression, one of the adhesion molecules was down regulated upon infection of endothelial cells with mycobacteria. No TNF-α and IL-6 were detected in culture supernatants of infected endothelial cells. Macrophages obtained from murine bone marrow, phagocytosed mycobacteria in both a dose- and a time-dependant manner. Unlike endothelial cells, heat killing of mycobacteria did not obliterate their uptake by macrophages. However, macrophages preferentially phagocytosed viable mycobacteria in a 3h infection period, but not in an 18h period. Macrophages from the Mac-l mouse strain, lacking a phagocytic receptor 3 (CR3), were included in this study. The uptake of pathogenic mycobacteria, H37Rv by macrophages from Mac-1, was reduced in cell cultures infected for 4 hours but not those infected at 1 and 2 hours. Similarly, reduced uptake of avirulent mycobacteria strains H3 7Ra and BCG in the absence of CR3 was pronounced in cell cultures infected for longer periods. The activation state macrophages acquire after infection with mycobacteria was investigated with respect to the expression of MHC glycoproteins, and secretion of IL-10 and IL-12. The activation state of macrophages with respect to these parameters studied is critical in the interaction with T-lymphocytes, for subsequent containment of mycobacteria infection. Production of IL-12, a critical Th-1 cytokine, was proportional to MOI, and enhanced by viability of pathogenic mycobacteria. Furthermore, prior exposure of mycobacteria to serum opsonins inhibited the secretion of IL-12, while exposure of the bacilli to bronchoalveolar factors greatly enhanced it. IL-10 production by infected macrophages was on the other hand inhibited by prior exposure of mycobacteria to both serum and bronchoalveolar ﬂuid factors. Macrophages consitutively expressed MHC I. After infection with pathogenic mycobacteria, cells positive for MHC I, were hardly detected in macrophage cultures infected with mycobacteria that had been exposed to fresh serum and bronchoalveolar fluid opsonins. MHC II on the other hand, was not consitutively expressed on macrophages. Following infection with pathogenic mycobacteria, the highest percentage of cells positive for the antibody against MHC II were observed in macrophage cultures infected both without any opsonin and in the presence of bronchoalveolar ﬂuid factors. - In conclusion, the present study demonstrates that endothelial cells bind and internalise mycobacteria. That they get activated as evidenced in the down-regulation of ICAM-1 following infection with mycobacteria. Thus endothelial cells may not just be a passive, physical barrier but host cells that may have an active role in mycobacterial infection. Macrophages in comparison to endothelial cells were more effective in phagocytosis of mycobacteria in a time- and dose-dependant manner, differentiating themselves as professional phagocytes in the internalisation of heat-killed bacteria where the endothelial cells lacked the ability for the uptake of mycobacteria.
Open Access
Limited Contribution of IL-36 versus IL-1 and TNF Pathways in Host Response to Mycobacterial Infection
(Public Library of Science, 2015) Segueni, Noria; Vigne, Solenne; Palmer, Gaby; Bourigault, Marie-Laure; Olleros, Maria L.; Vesin, Dominique; Garcia, Irene; Ryffel, Bernhard; Quesniaux, Valérie F. J.; Gabay, Cem
IL-36 cytokines are members of the IL-1 family of cytokines that stimulate dendritic cells and T cells leading to enhanced T helper 1 responses in vitro and in vivo ; however, their role in host defense has not been fully addressed thus far. The objective of this study was to examine the role of IL-36R signaling in the control of mycobacterial infection, using models of systemic attenuated M . bovis BCG infection and virulent aerogenic M . tuberculosis infection. IL-36γ expression was increased in the lung of M . bovis BCG infected mice. However, IL-36R deficient mice infected with M . bovis BCG showed similar survival and control of the infection as compared to wild-type mice, although their lung pathology and CXCL1 response were transiently different. While highly susceptible TNF-α deficient mice succumbed with overwhelming M . tuberculosis infection, and IL-1RI deficient mice showed intermediate susceptibility, IL-36R-deficient mice controlled the infection, with bacterial burden, lung inflammation and pathology, similar to wild-type controls. Therefore, IL-36R signaling has only limited influence in the control of mycobacterial infection.
Open Access
Membrane TNF confers protection to acute mycobacterial infection
(BioMed Central Ltd, 2005) Fremond, Cecile; Allie, Nasiema; Dambuza, Ivy M; Grivennikov, Sergei; Yeremeev, Vladimir; Quesniaux, Valerie; Jacobs, Muazzam; Ryffel, Bernhard
BACKGROUND:Tumour necrosis factor (TNF) is crucial for the control of mycobacterial infection as TNF deficient (KO) die rapidly of uncontrolled infection with necrotic pneumonia. Here we investigated the role of membrane TNF for host resistance in knock-in mice with a non-cleavable and regulated allele (mem-TNF). METHODS: C57BL/6, TNF KO and mem-TNF mice were infected with M. tuberculosis H37Rv (Mtb at 100 CFU by intranasal administration) and the survival, bacterial load, lung pathology and immunological parameters were investigated. Bone marrow and lymphocytes transfers were used to test the role of membrane TNF to confer resistance to TNF KO mice. RESULTS: While TNF-KO mice succumbed to infection within 4-5 weeks, mem-TNF mice recruited normally T cells and macrophages, developed mature granuloma in the lung and controlled acute Mtb infection. However, during the chronic phase of infection mem-TNF mice succumbed to disseminated infection with necrotic pneumonia at about 150 days. Reconstitution of irradiated TNF-KO mice with mem-TNF derived bone marrow cells, but not with lymphocytes, conferred host resistance to Mtb infection in TNF-KO mice. CONCLUSION: Membrane expressed TNF is sufficient to allow cell-cell signalling and control of acute Mtb infection. Bone marrow cells, but not lymphocytes from mem-TNF mice confer resistance to infection in TNF-KO mice. Long-term infection control with chronic inflammation likely disrupting TNF mediated cell-cell signalling, additionally requires soluble TNF.
Open Access
Mycobacterium tuberculosis and trypanosoma brucei as models for the TLR-dependent activation of the innate immune system
(2005) Drennan, Michael B; Ryffel, Bernhard; Magez, Stefan
Includes bibliographical references.
Open Access
Priming with a recombinant pantothenate auxotroph of Mycobacterium bovis BCG and boosting with MVA elicits HIV-1 Gag specific CD8+ T cells
(Public Library of Science, 2012) Chapman, Rosamund; Shephard, Enid; Stutz, Helen; Douglass, Nicola; Sambandamurthy, Vasan; Garcia, Irene; Ryffel, Bernhard; Jacobs, William; Williamson, Anna-Lise
A safe and effective HIV vaccine is required to significantly reduce the number of people becoming infected with HIV each year. In this study wild type Mycobacterium bovis BCG Pasteur and an attenuated pantothenate auxotroph strain (BCGΔ panCD ) that is safe in SCID mice, have been compared as vaccine vectors for HIV-1 subtype C Gag. Genetically stable vaccines BCG[pHS400] (BCG-Gag) and BCGΔ panCD [pHS400] (BCGpan-Gag) were generated using the Pasteur strain of BCG, and a panothenate auxotroph of Pasteur respectively. Stability was achieved by the use of a codon optimised gag gene and deletion of the hsp60-lysA promoter-gene cassette from the episomal vector pCB119. In this vector expression of gag is driven by the mtrA promoter and the Gag protein is fused to the Mycobacterium tuberculosis 19 kDa signal sequence. Both BCG-Gag and BCGpan-Gag primed the immune system of BALB/c mice for a boost with a recombinant modified vaccinia virus Ankara expressing Gag (MVA-Gag). After the boost high frequencies of predominantly Gag-specific CD8 + T cells were detected when BCGpan-Gag was the prime in contrast to induction of predominantly Gag-specific CD4 + T cells when priming with BCG-Gag. The differing Gag-specific T-cell phenotype elicited by the prime-boost regimens may be related to the reduced inflammation observed with the pantothenate auxotroph strain compared to the parent strain. These features make BCGpan-Gag a more desirable HIV vaccine candidate than BCG-Gag. Although no Gag-specific cells could be detected after vaccination of BALB/c mice with either recombinant BCG vaccine alone, BCGpan-Gag protected mice against a surrogate vaccinia virus challenge.
Open Access
Reactivation of persistant tuberculosis
(2003) Botha, Tania; Ryffel, Bernhard
Exposure to Mycobacterium tuberculosis results in clinical tuberculosis only in a small percentage of immunocompetent individuals. In most instances mycobacteria are controlled by the host immune system and survive in a dormant state within granuloma. lmmunosuppression, however, may result in reactivation of active tuberculosis resulting in clinical disease. Using low dose aerosol infection of M. tuberculosis in mice, a short-duration model of rifampicin-isoniazid (RMP-INH)-induced persistent tuberculosis is described. This persistent infection is characterised by undetectable levels of colony-forming units (CFU) in mouse organs and mice being clinically asymptomatic for prolonged periods. Reactivation of persistent tuberculosis can occur spontaneously following short-course chemotherapy or can be achieved by immunosuppression, speciﬁcally inhibition of macrophage- speciﬁc nitric oxide synthase (NOS2) by a chemical inhibitor, aminoguanidine. This model can therefore be used to characterise spontaneous or drug-induced reactivation of murine tuberculosis, as this is not feasible to study in human subjects. Additionally, this model may serve as a valuable tool for testing novel vaccines and antituberculous drugs, especially those designed to combat persistent infection. Mycobacterial genome copy enumeration and assessment of 168 ribosomal RNA (168 rRNA) and sigma factor A (sigA) gene expression revealed that large numbers of dormant bacilli are present in lung tissue during the persistent phase of infection in this model. This finding opens up the possibility that additional gene expression profiles can be analysed with current technology, unravelling the exact metabolic status of these dormant mycobacteria. Moreover, this model facilitates characterisation of another poorly understood aspect, namely reinfection. Preliminary aerosol reinfection during the persistent phase of tuberculosis revealed that the primary- infected dormant M. tuberculosis strain may be reactivated and may outgrow the primary strain during reinfection. Tumour necrosis factor (TNF) deﬁcient mice are known to be highly susceptible to M. tuberculosis infection. In this study it was asked whether TNF is required for post-infectious immunity in aerosol-infected mice. This model was applied and mice were treated with RlV|P-INH for 4 weeks to reduce the CFU to undetectable levels. While wild-type control mice spontaneously reactivated but controlled the infection upon cessation of chemotherapy, TNF deﬁcient mice developed fatal reactivation of infection. The increased susceptibility of TNF deficient mice was accompanied by diminished recruitment and activation of T cells and macrophages into the lung with defective granuloma formation and reduced inducible nitric oxide synthase expression. Reduced chemokine production in the lung might explain sub-optimal recruitment and activation of T cells and uncontrolled infection. Therefore, despite a massive reduction of the mycobacterial load by chemotherapy, TNF deficient mice were unable to compensate and mount a protective immune response. In conclusion, endogenous TNF is critical to maintain latent tuberculosis infection and in its absence no speciﬁc immunity is generated.
Open Access
The role of endotoxin receptors toll-like receptor 4 and lipopolysaccharide-binding protein in Mycobacterium tuberculosis infection
(2002) Abel, Brain; Ryffel, Bernhard
The aim of this study was to investigate the role of PRRs, namely TLR4 and LBP in vivo in the development of an immune response to a Mycobacterium tuberculosis infection. Mice with null mutations of the endotoxin receptors LBP and TLR4 were compared with wild-type mice (PRRs intact) in the context of an aerosol Mtb infection. The following questions were posed: Are the PRR-disrupted animals more susceptible to M.tuberculosis infection? What role do these PRRs play in inflammatory processes and in the development of granuloma? What role do the PRRs play in driving cytokine and chemokine response? Specifically, the following mice were infected aerogenically with Mtb H37Rv to further investigate their roles in vivo in mounting an effective immune response: C3H/HeN and C3H/ HeJ (TLR4 mutant) LBP+/+ and LBP-/-
Open Access
A study of the immune response in murine experimental malaria, with special reference to the effects of South African medicinal plants, artesunate and chloroquine
(2003) Gumede, Bonginkosi; Folb, Peter I; Ryffel, Bernhard
Open Access
TNF-dependent regulation and activation of innate immune cells are essential for host protection against cerebral tuberculosis
(BioMed Central Ltd, 2015) Francisco, Ngiambudulu; Hsu, Nai-Jen; Keeton, Roanne; Randall, Philippa; Sebesho, Boipelo; Allie, Nasiema; Govender, Dhirendra; Quesniaux, Valerie; Ryffel, Bernhard; Kellaway, Lauriston; Jacobs, Muazzam
BACKGROUND: Tuberculosis (TB) affects one third of the global population, and TB of the central nervous system (CNS-TB) is the most severe form of tuberculosis which often associates with high mortality. The pro-inflammatory cytokine tumour necrosis factor (TNF) plays a critical role in the initial and long-term host immune protection against Mycobacterium tuberculosis (M. tuberculosis) which involves the activation of innate immune cells and structure maintenance of granulomas. However, the contribution of TNF, in particular neuron-derived TNF, in the control of cerebral M. tuberculosis infection and its protective immune responses in the CNS were not clear. METHODS: We generated neuron-specific TNF-deficient (NsTNF / ) mice and compared outcomes of disease against TNF f/f control and global TNF / mice. Mycobacterial burden in brains, lungs and spleens were compared, and cerebral pathology and cellular contributions analysed by microscopy and flow cytometry after M. tuberculosis infection. Activation of innate immune cells was measured by flow cytometry and cell function assessed by cytokine and chemokine quantification using enzyme-linked immunosorbent assay (ELISA). RESULTS: Intracerebral M. tuberculosis infection of TNF / mice rendered animals highly susceptible, accompanied by uncontrolled bacilli replication and eventual mortality. In contrast, NsTNF / mice were resistant to infection and presented with a phenotype similar to that in TNF f/f control mice. Impaired immunity in TNF / mice was associated with altered cytokine and chemokine synthesis in the brain and characterised by a reduced number of activated innate immune cells. Brain pathology reflected enhanced inflammation dominated by neutrophil influx. CONCLUSION: Our data show that neuron-derived TNF has a limited role in immune responses, but overall TNF production is necessary for protective immunity against CNS-TB.

Browsing by Author "Ryffel, Bernhard"

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