krn-7000 and Pseudomonas-Infections

Topics: 4-Butyrolactone; Adjuvants, Immunologic; Animals; Anti-Bacterial Agents; Apoptosis; Cytokines; Disease Models, Animal; Galactosylceramides; Humans; Immunity, Cellular; Killer Cells, Natural; Legionnaires' Disease; Macrolides; Pneumonia, Pneumococcal; Pseudomonas aeruginosa; Pseudomonas Infections; Quorum Sensing; Th1 Cells; Vaccines

CD1d-restricted natural killer T (NKT) cells are emerging as critical regulators of the immune response to infectious agents, including Pseudomonas aeruginosa; and therapies to augment NKT-cell activation may represent a novel approach to treat chronic, antibiotic-resistant bacterial infections. We examined the capacity of dendritic cells (DCs) from people with cystic fibrosis (CF) to activate NKT cells. Our study was motivated by three lines of evidence: (i) NKT cells play a critical role in clearing P. aeruginosa infection; (ii) activation of NKT cells requires acidification-dependent processing of glycolipid antigens within the endolysosomal compartment; and (iii) endolysosomal acidification may be reduced in CF. We demonstrated that NKT-cell activation was dependent upon intact organelle acidification as inhibitors of the vacuolar (H(+))-ATPases prevented DCs from activating NKT cells with two glycolipid antigens, alpha-galactosylceramide and galactose-galactosylceramide. In contrast, cystic fibrosis transmembrane conductance regulator (CFTR) chloride channel dysfunction had no significant biological impact on the capacity of DCs to activate NKT cells. Dendritic cells from subjects with CF and DCs treated with the thiazolidinone CFTR(inh)-172 inhibitor showed no reduction in their ability to activate NKT cells. Based on these data, we find no evidence for an inherent defect in glycolipid antigen presentation to NKT cells in CF subjects.

Topics: Antigen Presentation; Antigens, Bacterial; Antigens, CD1d; Cystic Fibrosis; Cystic Fibrosis Transmembrane Conductance Regulator; Dendritic Cells; Drug Resistance, Bacterial; Endosomes; Female; Galactosylceramides; Humans; Lymphocyte Activation; Male; Natural Killer T-Cells; Pseudomonas aeruginosa; Pseudomonas Infections; Thiazolidinediones

CD1d-restricted NKT cells are reported to play a critical role in the host defense to pulmonary infection with Pseudomonas aeruginosa. However, the contribution of a major subset expressing a Valpha14-Jalpha18 gene segment remains unclear. In the present study, we re-evaluated the role of NKT cells in the neutrophilic inflammatory responses and host defense to this infection using mice genetically lacking Jalpha18 or CD1d (Jalpha18KO or CD1dKO mice). These mice cleared the bacteria in lungs at a comparable level to wild-type (WT) mice. There was no significant difference in the local neutrophilic responses, as shown by neutrophil counts and synthesis of MIP-2 and TNF-alpha, in either KO mice from those in WT mice. Administration of alpha-galactosylceramide, a specific activator of Valpha14+ NKT cells, failed to promote the bacterial clearance and neutrophilic responses, although the same treatment increased the synthesis of IFN-gamma, suggesting the involvement of this cytokine downstream of NKT cells. In agreement against this notion, these responses were not further enhanced by administration of recombinant IFN-gamma in the infected Jalpha18KO mice. Our data indicate that NKT cells play a limited role in the development of neutrophilic inflammatory responses and host defense to pulmonary infection with P. aeruginosa.

Topics: Animals; Cell Count; Chemokine CXCL2; Chemokines; Galactosylceramides; Immunologic Factors; Inflammation; Interferon-gamma; Killer Cells, Natural; Lung; Lymphocyte Subsets; Mice; Mice, Knockout; Neutrophils; Pneumonia, Bacterial; Pseudomonas aeruginosa; Pseudomonas Infections; T-Lymphocytes; Tumor Necrosis Factor-alpha

alpha-Galactosylceramide (alpha-GalCer), which is a specific ligand for CD1d restricted variable-alpha14chain natural killer T cells, has an important role in host defense against a range of microbial infections. We examined whether alpha-GalCer mediates bacterial clearance in a murine urinary tract infection (UTI) model.. The murine UTI model was established by intravesical inoculation of Escherichia coli, Pseudomonas aeruginosa or methicillin resistant Staphylococcus aureus, followed by clamping the distal end of the urethra of C57BL/6 female mice for 4 hours. The antibacterial effect of alpha-GalCer was assessed by comparing the number of cfu/gm kidney tissue 4 days after bacterial inoculation. The prophylactic effect of alpha-GalCer was examined by administrating 3 doses of intraperitoneal alpha-GalCer on alternate days 24 hours before E. coli inoculation. The therapeutic effect of alpha-GalCer was tested by the administration of 2 doses of intraperitoneal alpha-GalCer after bacterial inoculation. To assess cytokine induction by alpha-GalCer serum levels of interleukin-12, interferon-gamma and tumor necrosis factor-alpha were measured by cytometric bead array assay.. When administered before bacterial inoculation, alpha-GalCer showed a strong prophylactic antibacterial effect. alpha-GalCer also showed a marked antibacterial effect on preestablished mice UTI caused by E. coli, P. aeruginosa and methicillin resistant S. aureus. alpha-GalCer induced a significantly higher level of interleukin-12, interferon-gamma and tumor necrosis factor-alpha compared with control glycolipids.. These findings suggest a significant role for alpha-GalCer in regulating antibacterial functions by activating natural killer T cells in the murine UTI model.

Topics: Animals; Cytokines; Disease Models, Animal; Escherichia coli Infections; Female; Galactosylceramides; Killer Cells, Natural; Lymphocyte Activation; Mice; Mice, Inbred C57BL; Pseudomonas Infections; Staphylococcal Infections; Urinary Tract Infections