17 research outputs found
Role of the pattern recognition receptors : toll-like receptor 2 and CD14 in murine pneumococcal meningitis
Streptococcus pneumoniae is the major pathogen causing meningitis in adults. Despite antimicrobial therapy and critical care medicine, mortality remains high and about 50% of the survivors suffer from neurological sequelae. In the present study, the function of the pattern recognition receptors TLR2 and CD14 in mediating host innate immune response towards S. pneumoniae, was investigated in a mouse model of pneumococcal meningitis using mice with a targeted deletion of the corresponding genes. The role of TLR2 and CD14 are the topics of sections I and II. Modulation of outcome in wt, TLR2-/- and CD14-/- mice with meningitis by antibiotic and/or with anti-inflammatory treatment with TNF-alpha converting enzyme (TACE) inhibitor treatment is evaluated in section III.
TLR2-/- mice were found to have more severe clinical symptoms than did wt mice and subsequently showed earlier death during meningitis. This accelerated death was not due to sepsis, but rather to reduced brain bacterial clearing, followed by increased intrathecal inflammation. While the lack of TLR2 delayed bacterial clearance, leukocyte infiltration and enhanced inflammation, the lack or blockade of CD14 had no effect on bacterial clearance, but was associated with a stronger neutrophil recruitment into CSF, leading to excessive meningeal inflammation and aggravated disease after S. pneumoniae infection. In addition, this stronger neutrophil migration correlated with MIP-2 concentrations in brain and with enhanced migratory capacity of CD14-deficient PMN. In view of our observations, that different host effector functions were modulated by TLR2 and CD14 during meningitis, we asked the question whether response to therapy was also modulated by these two pattern recognition receptors. We found, that antibiotic treatment was efficient to rescue wt and CD14-/- mice, whereas in TLR2-/- strain, combination with TACE inhibitor was required. This study reveals the different effects mediated by TLR2 and CD14 respectively in meningitis and illustrates the requirement and success of adjuvant therapy, when bacterial load is high and inflammation is strong in TLR2-/- mice
Toll-Like Receptor 2-Deficient Mice Are Highly Susceptible to Streptococcus pneumoniae Meningitis because of Reduced Bacterial Clearing and Enhanced Inflammation
Toll-like receptor-2 (TLR2) mediates host responses to gram-positive bacterial wall components. TLR2 function was investigated in a murine Streptococcus pneumoniae meningitis model in wild-type (wt) and TLR2-deficient (TLR2−/−) mice. TLR2−/− mice showed earlier time of death than wt mice (P<.02). Plasma interleukin-6 levels and bacterial numbers in blood and peripheral organs were similar for both strains. With ceftriaxone therapy, none of the wt but 27% of the TLR2−/− mice died (P<.04). Beyond 3 hours after infection, TLR2−/− mice had higher bacterial loads in brain than did wt mice, as assessed with luciferase-tagged S. pneumoniae by means of a Xenogen-CCD (charge-coupled device) camera. After 24 h, tumor necrosis factor activity was higher in cerebrospinal fluid of TLR2−/− than wt mice (P<.05) and was related to increased blood-brain barrier permeability (Evans blue staining, P<.02). In conclusion, the lack of TLR2 was associated with earlier death from meningitis, which was not due to sepsis but to reduced brain bacterial clearing, followed by increased intrathecal inflammatio
Adjuvant TACE inhibitor treatment improves the outcome of TLR2(-/- )mice with experimental pneumococcal meningitis
BACKGROUND: Streptococcus (S.) pneumoniae meningitis has a high lethality despite antibiotic treatment. Inflammation is a major pathogenetic factor, which is unresponsive to antibiotics. Therefore adjunctive therapies with antiinflammatory compounds have been developed. TNF484 is a TNF-alpha converting enzyme (TACE) inhibitor and has been found efficacious in experimental meningitis. Toll-like receptor 2 (TLR2) contributes to host response in pneumococcal meningitis by enhancing bacterial clearing and downmodulating inflammation. In this study, TNF484 was applied in mice, which lacked TLR2 and exhibited a strong meningeal inflammation. METHODS: 10(3 )CFU S. pneumoniae serotype 3 was inoculated subarachnoidally into C57BL/6 wild type (wt) mice or TLR2(-/-), CD14(-/- )and CD14(-/-)/TLR2(-/- )mice. Severity of disease and survival was followed over 9 days. Response to antibiotics (80 mg/kg ceftriaxone i.p. for 5 days) and/or TACE inhibitor treatment (1 mg/kg s.c. twice daily for 4 days) was evaluated. Animals were sacrificed after 12, 24, and 48 h for analysis of bacterial load in cerebrospinal fluid (CSF) and brain and for TNF and leukocyte measurements in CSF. RESULTS: TLR2(-/- )mice were significantly sicker than the other mouse strains 24 h after infection. All knockout mice showed higher disease severity after 48 h and died earlier than wt mice. TNF release into CSF was significantly more elevated in TLR2(-/- )than in the other strains after 24 h. Brain bacterial numbers were significantly higher in all knockout than wt mice after 24 h. Modulation of outcome by antibiotic and TACE inhibitor treatment was evaluated. With antibiotic therapy all wt, CD14(-/- )and TLR2(-/-)/CD14(-/- )mice, but only 79% of TLR2(-/- )mice, were rescued. TACE inhibitor treatment alone did not rescue, but prolonged survival in wt mice, and in TLR2(-/- )and CD14(-/- )mice to the values observed in untreated wt mice. By combined antibiotic and TACE inhibitor treatment 95% of TLR2(-/- )mice were rescued. CONCLUSION: During pneumococcal meningitis strong inflammation in TLR2-deficiency was associated with incomplete responsiveness to antibiotics and complete response to combined antibiotic and TACE inhibitor treatment. TACE inhibitor treatment offers a promising adjuvant therapeutic strategy in pneumococcal meningitis
Δ133p53α enhances metabolic and cellular fitness of TCR-engineered T cells and promotes superior antitumor immunity
Background Tumor microenvironment-associated T cell senescence is a key limiting factor for durable effective cancer immunotherapy. A few studies have demonstrated the critical role of the tumor suppressor TP53-derived p53 isoforms in cellular senescence process of non-immune cells. However, their role in lymphocytes, in particular tumor-antigen (TA) specific T cells remain largely unexplored.Methods Human T cells from peripheral blood were retrovirally engineered to coexpress a TA-specific T cell receptor and the Δ133p53α-isoform, and characterized for their cellular phenotype, metabolic profile and effector functions.Results Phenotypic analysis of Δ133p53α-modified T cells revealed a marked reduction of the T-cell inhibitory molecules (ie, CD160 and TIGIT), a lower frequency of senescent-like CD57+ and CD160+ CD8+ T cell populations, and an increased number of less differentiated CD28+ T cells. Consistently, we demonstrated changes in the cellular metabolic program toward a quiescent T cell state. On a functional level, Δ133p53α-expressing T cells acquired a long-term proliferative capacity, showed superior cytokine secretion and enhanced tumor-specific killing in vitro and in mouse tumor model. Finally, we demonstrated the capacity of Δ133p53α to restore the antitumor response of senescent T cells isolated from multiple myeloma patients.Conclusion This study uncovered a broad effect of Δ133p53α isoform in regulating T lymphocyte function. Enhancing fitness and effector functions of senescent T cells by modulation of p53 isoforms could be exploited for future translational research to improve cancer immunotherapy and immunosenescence-related diseases
Toll-like receptor 2-deficient mice are highly susceptible to Streptococcus pneumoniae meningitis because of reduced bacterial clearing and enhanced inflammation
Toll-like receptor-2 (TLR2) mediates host responses to gram-positive bacterial wall components. TLR2 function was investigated in a murine Streptococcus pneumoniae meningitis model in wild-type (wt) and TLR2-deficient (TLR2(-/-)) mice. TLR2(-/-) mice showed earlier time of death than wt mice (P<.02). Plasma interleukin-6 levels and bacterial numbers in blood and peripheral organs were similar for both strains. With ceftriaxone therapy, none of the wt but 27% of the TLR2(-/-) mice died (P<.04). Beyond 3 hours after infection, TLR2(-/-) mice had higher bacterial loads in brain than did wt mice, as assessed with luciferase-tagged S. pneumoniae by means of a Xenogen-CCD (charge-coupled device) camera. After 24 h, tumor necrosis factor activity was higher in cerebrospinal fluid of TLR2(-/-) than wt mice (P<.05) and was related to increased blood-brain barrier permeability (Evans blue staining, P<.02). In conclusion, the lack of TLR2 was associated with earlier death from meningitis, which was not due to sepsis but to reduced brain bacterial clearing, followed by increased intrathecal inflammation
Toll-Like Receptor 2 Deficiency Delays Pneumococcal Phagocytosis and Impairs Oxidative Killing by Granulocytes
Phagocytosis and killing of Streptococcus pneumoniae was compared in blood-derived wild-type (WT) and Toll-like receptor 2 (TLR2)-deficient (TLR2(−/−)) polymorphonuclear leukocytes (PMN). Phagocytosis of green fluorescent protein-transformed pneumococci was delayed in TLR2(−/−) PMN. These cells exhibited also a lower oxidative bactericidal activity against S. pneumoniae than WT PMN, suggesting that TLR2 modulates bacterial clearance in PMN