RESUMO
BACKGROUND: Leptin regulates appetite through the long isoform of its receptor in the hypothalamus. Although leptin regulates immune responses, it is still unknown whether a direct effect of leptin on lymphocytes is required. AIMS: To clarify whether expression of leptin receptors on T lymphocytes modulates intestinal inflammation in mice. METHODS: The model of colitis induced by transfer of CD4(+)CD45RB(high) (RB(high)) cells into scid mice was used. Wild-type (WT) or leptin receptor deficient (db/db) RB(high) cells were transferred into scid mice and development of colitis evaluated. RESULTS: Leptin receptors were expressed on both RB(high) and RB(low) cells. Intestinal lymphocytes of mice with colitis expressed high leptin levels compared with healthy controls whereas the opposite was true for serum leptin levels. Transfer of RB(high) cells from db/db mice induced delayed disease compared with transfer of WT cells. A high rate of apoptosis in lamina propria lymphocytes and reduced cytokine production were observed early on in scid mice receiving db/db RB(high) cells. These effects were not due to the high levels of glucocorticoids present in db/db mice as administration of corticosterone to WT mice failed to reproduce this phenomenon. High expression of peroxisome proliferator activated receptor gamma was observed in the colon of recipients of db/db compared with WT cells. Freshly isolated db/db RB(high) cells produced low levels of interferon gamma. Despite delayed onset of colitis, as disease progressed differences between mice receiving WT or db/db cells were no longer apparent. CONCLUSIONS: These results suggest that leptin affects the immune response, partly by acting on the long isoform of its receptor expressed on T lymphocytes.
Assuntos
Colite/imunologia , Receptores de Superfície Celular/imunologia , Linfócitos T/imunologia , Animais , Doença Crônica , Corticosterona/sangue , Citocinas/biossíntese , Progressão da Doença , Suscetibilidade a Doenças , Imunidade nas Mucosas , Leptina/imunologia , Antígenos Comuns de Leucócito/análise , Transfusão de Linfócitos , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos SCID , Receptores para Leptina , Células Th1/imunologiaRESUMO
The contribution of the NADPH phagocyte oxidase (phox) and inducible nitric oxide (NO) synthase (iNOS) to the antimicrobial activity of macrophages for Salmonella typhimurium was studied by using peritoneal phagocytes from C57BL/6, congenic gp91phox(-/)-, iNOS(-/)-, and doubly immunodeficient phox(-/)-iNOS(-/)- mice. The respiratory burst and NO radical (NO.) made distinct contributions to the anti-Salmonella activity of macrophages. NADPH oxidase-dependent killing is confined to the first few hours after phagocytosis, whereas iNOS contributes to both early and late phases of antibacterial activity. NO-derived species initially synergize with oxyradicals to kill S. typhimurium, and subsequently exert prolonged oxidase-independent bacteriostatic effects. Biochemical analyses show that early killing of Salmonella by macrophages coincides with an oxidative chemistry characterized by superoxide anion (O(2).(-)), hydrogen peroxide (H(2)O(2)), and peroxynitrite (ONOO(-)) production. However, immunofluorescence microscopy and killing assays using the scavenger uric acid suggest that peroxynitrite is not responsible for macrophage killing of wild-type S. typhimurium. Rapid oxidative bacterial killing is followed by a sustained period of nitrosative chemistry that limits bacterial growth. Interferon gamma appears to augment antibacterial activity predominantly by enhancing NO. production, although a small iNOS-independent effect was also observed. These findings demonstrate that macrophages kill Salmonella in a dynamic process that changes over time and requires the generation of both reactive oxidative and nitrosative species.
Assuntos
Macrófagos Peritoneais/imunologia , Glicoproteínas de Membrana/fisiologia , NADPH Oxidases/fisiologia , Óxido Nítrico Sintase/fisiologia , Fagocitose , Salmonella typhimurium/imunologia , Animais , Ativação de Macrófagos , Macrófagos Peritoneais/metabolismo , Camundongos , Camundongos Endogâmicos C57BL , NADPH Oxidase 2 , Óxido Nítrico Sintase Tipo II , Espécies Reativas de Oxigênio , Superóxidos/metabolismo , Tirosina/análogos & derivados , Tirosina/metabolismoRESUMO
A type III protein secretion system encoded by Salmonella pathogenicity island 2 (SPI2) has been found to be required for virulence and survival within macrophages. Here, SPI2 was shown to allow Salmonella typhimurium to avoid NADPH oxidase-dependent killing by macrophages. The ability of SPI2-mutant bacteria to survive in macrophages and to cause lethal infection in mice was restored by abrogation of the NADPH oxidase-dependent respiratory burst. Ultrastructural and immunofluorescence microscopy demonstrated efficient localization of the NADPH oxidase in the proximity of vacuoles containing SPI2-mutant but not wild-type bacteria, suggesting that SPI2 interferes with trafficking of oxidase-containing vesicles to the phagosome.
Assuntos
Hidróxidos , Macrófagos Peritoneais/enzimologia , Macrófagos Peritoneais/microbiologia , NADPH Oxidases/metabolismo , Salmonella typhimurium/genética , Salmonella typhimurium/patogenicidade , Animais , Proteínas de Bactérias/genética , Proteínas de Bactérias/fisiologia , Cério/análise , Genes Bacterianos , Macrófagos Peritoneais/ultraestrutura , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Microscopia Eletrônica , Microscopia de Fluorescência , Peróxidos/análise , Fagossomos/microbiologia , Explosão Respiratória , Salmonelose Animal/microbiologia , Salmonella typhimurium/fisiologia , Superóxidos/metabolismo , Acetato de Tetradecanoilforbol/farmacologia , Vacúolos/enzimologia , Vacúolos/microbiologia , VirulênciaRESUMO
Although highly susceptible to orogastric candidiasis, T-cell receptor delta- and alpha-chain knockout mice, deficient in gammadelta and alphabeta T cells, respectively, were found to be resistant to disseminated candidiasis of endogenous origin and to acute systemic candidiasis (resulting from intravenous injection).
Assuntos
Candidíase/imunologia , Linfócitos T/imunologia , Animais , Encéfalo/microbiologia , Candida albicans/metabolismo , Contagem de Colônia Microbiana , Esôfago/microbiologia , Esôfago/patologia , Rim/microbiologia , Fígado/microbiologia , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Mucosa/imunologia , Mucosa/microbiologia , Receptores de Antígenos de Linfócitos T/imunologia , Receptores de Antígenos de Linfócitos T/fisiologia , Baço/microbiologia , Estômago/microbiologia , Estômago/patologia , Subpopulações de Linfócitos T/imunologia , Subpopulações de Linfócitos T/fisiologia , Linfócitos T/fisiologia , Fatores de TempoRESUMO
The role of leptin was investigated in two models of T cell-mediated hepatitis: the administration of Con A or of Pseudomonas aeruginosa exotoxin A (PEA). In both models, leptin-deficient (ob/ob) mice were protected from liver damage and showed lower induction of tumor necrosis factor (TNF) alpha and IL-18 compared with their lean littermates. Neutralization of TNF-alpha reduced induction of IL-18 by either Con A (70% reduction) or PEA (40% reduction). Pretreatment of lean mice with either soluble TNF receptors or with an anti-IL-18 antiserum significantly reduced Con A- and PEA-induced liver damage. The simultaneous neutralization of TNF-alpha and IL-18 fully protected the mice against liver toxicity. However, neutralization of either IL-18 or TNF-alpha did not inhibit Con A-induced production of IFN-gamma. Thymus atrophy and alterations in the number of circulating lymphocytes and monocytes were observed in ob/ob mice. Exogenous leptin replacement restored the responsiveness of ob/ob mice to Con A and normalized their lymphocyte and monocyte populations. These results demonstrate that leptin deficiency leads to reduced production of TNF-alpha and IL-18 associated with reduced T cell-mediated hepatotoxicity. In addition, both TNF-alpha and IL-18 appear to be essential mediators of T cell-mediated liver injury.
Assuntos
ADP Ribose Transferases , Toxinas Bacterianas , Doença Hepática Induzida por Substâncias e Drogas/imunologia , Interleucina-18/imunologia , Leptina/imunologia , Linfócitos T/imunologia , Fator de Necrose Tumoral alfa/imunologia , Fatores de Virulência , Animais , Doença Hepática Induzida por Substâncias e Drogas/metabolismo , Concanavalina A/toxicidade , Exotoxinas/toxicidade , Feminino , Interleucina-18/metabolismo , Leptina/farmacologia , Fígado/efeitos dos fármacos , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Camundongos Obesos , Fator de Necrose Tumoral alfa/metabolismo , Exotoxina A de Pseudomonas aeruginosaRESUMO
Specialized epithelia known as M cells overlying the lymphoid follicles of Peyer's patches are important in the mucosal immune system, but also provide a portal of entry for pathogens such as Salmonella typhimurium, Mycobacterium bovis, Shigella flexneri, Yersinia enterocolitica and reoviruses. Penetration of intestinal M cells and epithelial cells by Salmonella typhimurium requires the invasion genes of Salmonella Pathogenicity Island 1 (SPI1). SPI1-deficient S. typhimurium strains gain access to the spleen following oral administration and cause lethal infection in mice without invading M cells or localizing in Peyer's patches, which indicates that Salmonella uses an alternative strategy to disseminate from the gastrointestinal tract. Here we report that Salmonella is transported from the gastrointestinal tract to the bloodstream by CD18-expressing phagocytes, and that CD18-deficient mice are resistant to dissemination of Salmonella to the liver and spleen after oral administration. This CD18-dependent pathway of extraintestinal dissemination may be important for the development of systemic immunity to gastrointestinal pathogens, because oral challenge with SPI1-deficient S. typhimurium elicits a specific systemic IgG humoral immune response, despite an inability to stimulate production of specific mucosal IgA.
Assuntos
Antígenos CD18/metabolismo , Intestinos/microbiologia , Fagócitos/microbiologia , Salmonelose Animal/microbiologia , Salmonella typhimurium/fisiologia , 3-Fosfoshikimato 1-Carboxiviniltransferase , Alquil e Aril Transferases/genética , Animais , Bacteriemia/microbiologia , Proteínas de Bactérias/genética , Transporte Biológico , Antígenos CD18/genética , Fímbrias Bacterianas/genética , Genes Bacterianos , Imunidade nas Mucosas , Mucosa Intestinal/metabolismo , Camundongos , Camundongos Endogâmicos C57BL , Mutagênese , Fagócitos/metabolismo , Salmonelose Animal/imunologia , Salmonella typhimurium/genética , Salmonella typhimurium/imunologia , Salmonella typhimurium/patogenicidadeRESUMO
Wound healing is a complex process that involves inflammation, apoptosis, growth, and tissue remodeling. The autoimmune-prone inbred mouse strain MRL/+ manifests accelerated and extensive healing to ear punch wounds, suggesting a link between immune defects and wound healing. Prior studies with lupus-prone mice have shown that hematopoietic cells of lupus-prone strains can transfer disease to otherwise non-autoimmune-prone recipients. In this study we performed reciprocal bone marrow transfers between MRL and the control strain B10.BR and found that radioresistant MRL/+ host cells, rather than hematopoietic cells, are required for the healing response. We have also made the novel observations that, compared to normal controls, MRL/+ hematopoietic cells overproduce TGF-beta1 and manifest impaired inflammatory responses to lipopolysaccharide challenge. These features suggest that the aberrant wound healing phenotype of MRL mice is independent of their propensity to develop autoimmunity.
Assuntos
Camundongos Endogâmicos MRL lpr/metabolismo , Fator de Crescimento Transformador beta/metabolismo , Cicatrização/fisiologia , Envelhecimento/genética , Envelhecimento/fisiologia , Animais , Transplante de Medula Óssea , Líquido da Lavagem Broncoalveolar/citologia , Genótipo , Células-Tronco Hematopoéticas/metabolismo , Mediadores da Inflamação/metabolismo , Lipopolissacarídeos/farmacologia , Camundongos , Neutrófilos/citologia , Pneumonia/fisiopatologia , Quimeras de Transplante , Cicatrização/genéticaRESUMO
Germ-free BALB/c mice, genetically engineered to be deficient for interleukin-8 (IL-8) receptor homolog (IL-8Rh-/-), were more susceptible to gastric candidiasis after oral challenge and to acute systemic candidiasis after intravenous challenge than IL-8Rh+/+ controls. In comparison to IL-8Rh+/+ mice, the IL-8Rh-/- mice had slower influx of polymorphonuclear neutrophils (PMN) into Candida albicans-infected tissues and a lower percentage of PMN in peritoneal exudate cells (PEC) elicited with heat-killed C. albicans. PEC from IL-8Rh-/- mice exhibited less luminol-dependent chemiluminescence in response to C. albicans and did not kill C. albicans hyphae as well as PEC from IL-8Rh+/+ mice. C. albicans-colonized IL-8Rh-/- mice showed no histological evidence of systemic candidiasis. These results suggest a role for the IL-8Rh in murine resistance to gastric and acute systemic candidiasis, but not in resistance to systemic candidiasis of endogenous origin.
Assuntos
Antígenos CD/fisiologia , Candidíase/imunologia , Enteropatias/imunologia , Receptores de Interleucina/fisiologia , Doença Aguda , Animais , Antígenos CD/genética , Candidíase/microbiologia , Candidíase/patologia , Feminino , Indicadores e Reagentes , Injeções Intravenosas , Enteropatias/microbiologia , Enteropatias/patologia , Mucosa Intestinal/imunologia , Mucosa Intestinal/microbiologia , Mucosa Intestinal/patologia , Medições Luminescentes , Luminol , Masculino , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Knockout , Neutrófilos/imunologia , Receptores de Interleucina/genética , Receptores de Interleucina-8ARESUMO
PURPOSE: Clinical and experimental evidence indicates that mucosal immunity to urinary tract infection involves B and T-cell functions. The present study was conducted to assess the susceptibility of immunocompetent and immunodeficient mice with genetically engineered deletions in T and B-cell functions to experimentally induced urinary tract infections (UTI) with Escherichia coli. MATERIALS AND METHODS: Interferon-gamma (IFN-gamma), interleukin-4 (IL-4), IL-10, inducible nitric oxide synthase, T cell receptor (TCR) delta-chain and JHD B cell-deficient gene knockout mice and their immunocompetent controls were challenged with uropathogenic Escherichia coli. The bladders and kidneys were cultured for viable E. coli at time intervals after intraurethral challenge to assess susceptibility to an experimentally induced UTI. RESULTS: Knockout mice with gammadelta-T cell or IFN-gamma deficiencies were more susceptible to UTI than immunocompetent mice or mice with immunodeficiencies in IL-10, IL-4, inducible nitric oxide synthase or antibody production (JHD). CONCLUSIONS: These data support an important role for gammadelta-T cells and IFN-gamma in resistance to UTI in mice.
Assuntos
Infecções por Escherichia coli/imunologia , Hospedeiro Imunocomprometido , Camundongos Knockout/imunologia , Infecções Urinárias/imunologia , Animais , Suscetibilidade a Doenças , CamundongosAssuntos
Receptores de Antígenos de Linfócitos T gama-delta , Subpopulações de Linfócitos T/fisiologia , Animais , Formação de Anticorpos/fisiologia , Linfócitos B/fisiologia , Homeostase/imunologia , Humanos , Tolerância Imunológica/imunologia , Imunidade Celular , Inflamação/imunologia , Células Matadoras Naturais/fisiologia , Ativação Linfocitária , Cooperação Linfocítica , Macrófagos/fisiologia , Complexo Principal de Histocompatibilidade/imunologia , Camundongos , Receptores de Antígenos de Linfócitos T gama-delta/genética , Receptores de Antígenos de Linfócitos T gama-delta/imunologia , Receptores de Antígenos de Linfócitos T gama-delta/metabolismo , Subpopulações de Linfócitos T/química , Subpopulações de Linfócitos T/imunologia , Imunologia de TransplantesRESUMO
In contrast to immunocompetent controls, interleukin-10 (IL-10) knockout (KO) mice eliminated an experimental intravenous inoculation with Candida albicans from their kidneys. Improved clearance of C. albicans from the kidneys of IL-10 KO mice was evident at 24 h after intravenous challenge with the fungus. Conversely, mice with a deletion of the IL-4 cytokine gene were more susceptible to systemic candidiasis than were immunocompetent controls. The hyperresistance of IL-10 KO mice to acute systemic candidiasis did not seem to correlate with nitric oxide-mediated immunity, but rather, it appeared to be associated with more efficient effector function of innate cells, possibly neutrophils. In support of the latter hypothesis, we observed that neutrophils from IL-10 KO mice were more efficient at killing C. albicans blastoconidia and hyphae than were neutrophils from immunocompetent control mice. Neither IL-10 KO nor IL-4 KO mice that were monoassociated with C. albicans for 4 weeks showed any histologic evidence of systemic candidiasis of endogenous origin. In contrast to systemic candidiasis, we observed no significant (P < 0.05) differences in susceptibility among IL-10 KO, IL-4 KO, and wild-type (immunocompetent) mice to orogastric candidiasis. Our results suggest that IL-10 exerts a negative effect on the early, innate response to acute systemic candidiasis; however, in comparison to immunocompetent control (wild-type) mice, neither IL-10 nor IL-4 deficiency enhanced susceptibility to orogastric candidiasis.
Assuntos
Candidíase/imunologia , Interleucina-10/imunologia , Doença Aguda , Animais , Inibidores Enzimáticos/farmacologia , Feminino , Guanidinas/farmacologia , Imunidade Inata/imunologia , Interleucina-10/genética , Interleucina-4/genética , Interleucina-4/imunologia , Masculino , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Endogâmicos C57BL , Camundongos Knockout , Neutrófilos/imunologia , Neutrófilos/microbiologiaRESUMO
B cell-deficient mice have normal T cell responses to Ags inoculated systemically; however, it is not known whether they can mount systemic and mucosal T cell responses to Ags through normally B cell-enriched gastrointestinal mucosae. Mucosal colonization of germfree, B cell-deficient J(H)D mice with the pathogenic gastrointestinal fungus, Candida albicans selected splenic CD4+ and CD8+ TCR alphabeta memory T cells, as indicated by 1) increased numbers of splenic CD4+ and CD8+ TCR alphabeta expressing T cells of the CD45RB(low) CD44(high) phenotype, 2) early expansion followed by progressive decrease in the number of splenic CD4+ and CD8+ TCR alphabeta T cells, and 3) concomitant increases in the percentage of apoptosis and proliferation in the latter subsets. Although i.v. challenge of germfree or conventional J(H)D mice with C. albicans did not increase apoptosis or induce changes in the number of splenic memory T cells, i.v. challenge of mucosally immunized germfree J(H)D mice led to further proliferation and expansion of activated splenic CD4+ and CD8+ TCR alphabeta thymic-educated memory T cells, which were first evoked by mucosal immunization. Oral colonization with C. albicans also increased the number of gammadelta and thymic and extrathymic alphabeta T cells in gastrointestinal mucosae. In conclusion, our results are the first strong evidence that thymic and extrathymic T cells participate in mucosal immunity to C. albicans in the absence of B cells; however, CD4+ and thymic-educated CD8+ TCR alphabeta memory subsets evoked by mucosal, but not parenteral (i.v.), challenge contribute to protective immunity to systemic candidiasis.
Assuntos
Linfócitos B/imunologia , Candida albicans/imunologia , Candidíase/imunologia , Imunidade nas Mucosas , Memória Imunológica , Linfócitos T/imunologia , Animais , Antígenos de Fungos/administração & dosagem , Apoptose , Vida Livre de Germes , Imunofenotipagem , Ativação Linfocitária , Camundongos , Camundongos Mutantes , Baço/imunologiaRESUMO
Barrier-raised transforming growth factor beta 1 (TGF beta 1)-deficient mice consistently die before 35 days of age of a severe multiorgan inflammatory disease that can affect the skeletal muscle, heart, liver, pancreas, salivary gland, lung, oesophagus and stomach. The underlying cause of this disease is not known. To determine whether abnormal responsiveness of the immune system to the presence of enteric flora plays a causative role, a colony of TGF beta 1-deficient and wild-type mice were raised in a sterile environment. Seven germ-free TGF beta 1-deficient and 5 germ-free TGF beta 1 wild-type mice were examined. Lesion development was analysed and compared with historical data on 50 barrier-raised TGF beta 1 mutant mice and 32 barrier-raised wild-type mice. All germ-free TGF beta 1-deficient mice died shortly after weaning, as do their barrier-raised counterparts. There was a significant delay in death in germ-free TGF beta 1-deficient mice compared with barrier-raised mutant mice. However, there was no difference in the type, severity or incidence of lesions between TGF beta 1 mutant mice raised under germ-free or barrier conditions. Germ-free wild-type mice had no lesions. It is concluded that microorganisms play a minimal role in disease induction in TGF beta 1-deficient mice.
Assuntos
Vida Livre de Germes/fisiologia , Inflamação/patologia , Fator de Crescimento Transformador beta/deficiência , Fator de Crescimento Transformador beta/genética , Animais , Hiperplasia/patologia , Inflamação/fisiopatologia , Longevidade/fisiologia , Camundongos , Camundongos Endogâmicos , Camundongos Mutantes , Estômago/patologia , Úlcera Gástrica/patologia , Úlcera/patologiaRESUMO
beta2-Microglobulin knockout (beta2m-/-) mice, which lack major histocompatibility complex class I expression and are deficient in CD8alpha/beta T-cell receptor alpha/beta (TcRalpha/beta) T cells, were as resistant to systemic (intravenous) challenge with Candida albicans as immunocompetent controls. Conversely, the beta2m-/- mutant mice were susceptible to systemic candidiasis of endogenous origin despite the induction of C. albicans-specific antibody and cell-mediated immune responses after colonization with a pure culture of C. albicans. Despite some superficial and transient infections of tongues and esophagi (detected by histology) at 1 to 2 weeks after oral colonization and gastric infections (cardia-antrum section) which were observed at 10 to 12 weeks after oral challenge, C. albicans-colonized beta2m-/- mice showed an overall resistance to candidiasis in other mucosal and cutaneous tissues. These data suggest that immune defects that accompany the loss of beta2-microglobulin play an important role in murine resistance to gastric and disseminated candidiasis of endogenous (intestinal tract) origin and that innate immunity and CD4 TcRalpha/beta as well as CD8alpha/alpha TcRalpha/beta (or -gamma/delta) T cells play an important role in resistance to systemic, cutaneous, and nongastric mucosal tissues.
Assuntos
Candidíase/imunologia , Antígenos de Histocompatibilidade Classe I/imunologia , Receptores de Antígenos de Linfócitos T alfa-beta/imunologia , Microglobulina beta-2/imunologia , Animais , Candidíase/genética , Regulação da Expressão Gênica , Antígenos de Histocompatibilidade Classe I/genética , Camundongos , Camundongos Knockout , Receptores de Antígenos de Linfócitos T alfa-beta/genética , Microglobulina beta-2/genéticaRESUMO
Germfree J(H)D mice, which lack functional B cells and antibodies, were as resistant to orogastric and disseminated candidiasis of endogenous origin as were immunocompetent controls. Newborn J(H)D mice, in contrast to adult mice, were resistant to alimentary tract colonization by Candida albicans for 5-7 days after birth. C. albicans-colonized J(H)D mice were more resistant to intravenous challenge with C. albicans and had greater splenocyte proliferative responses to C. albicans antigens than did germfree mice or conventional controls. Thus, innate and acquired T cell-mediated immune responses induced after oral immunization are sufficient to protect J(H)D mice from mucosal and systemic candidiasis of endogenous origin; however, functional B cells may be required to protect mice from a primary intravenous challenge with C. albicans.
Assuntos
Linfócitos B/imunologia , Candidíase/imunologia , Hospedeiro Imunocomprometido , Animais , Formação de Anticorpos/imunologia , Western Blotting , Encéfalo/microbiologia , Doenças do Sistema Digestório/microbiologia , Vida Livre de Germes , Imunidade Celular , Imunidade Inata/imunologia , Infusões Intravenosas , Interferon gama/análise , Interleucina-4/análise , Rim/microbiologia , Fígado/microbiologia , Camundongos , Camundongos Knockout , Baço/microbiologiaRESUMO
Nitric oxide (NO) is associated with functions as diverse as peristalsis, blood flow, neuroendosecretion, visual transduction, smooth muscle relaxation, and microbial killing (H. H. W. H. Schmidt and V. Walter, Cell 78:919-925, 1994). Despite the well-established role of NO in macrophage candidacidal activity (E. Cenci, L. Romani, A. Mancacci, R. Spaccapelo, E. Schiaffella, P. Puccetti, and F. Bistoni, Eur. J. Immunol. 23:1034-1038, 1993; J. Jones-Carson, A. Vazquez-Torres, H. Van der Heide, R. D. Wagner, T. Warner, and E. Balish, Nature Med. 1:552-557, 1995; and A. Vazquez-Torres, J. Jones-Carson, T. Warner, and E. Balish, J. Infect. Dis. 172:192-198, 1995), NO is not directly candidacidal for Candida albicans (A. Vazquez-Torres, J. Jones-Carson, and E. Balish, Infect. Immun. 63:1142-1144, 1995). Because macrophages can produce both NO and superoxide anion (02-), we postulated that peroxynitrite (ONOO-), a product of the dilution-limited reaction of NO and O2-, is the candidacidal molecule of activated macrophages. We now report that ONOO-, in addition to being candidacidal in vitro, is responsible for the candidacidal activity of NO-producing macrophages. ONOO- synthesis by NO-producing macrophages was triggered by two independent mechanisms: one was nonopsonic and dependent on fungal cell wall glucan moieties, and the other was dependent on opsonic antibodies. As we have demonstrated for the pathogenic fungus C. albicans, ONOO- may also be the molecule that enables macrophages to kill other microbes that are resistant to both O2- and NO.
Assuntos
Antifúngicos/farmacologia , Candida albicans/efeitos dos fármacos , Macrófagos Peritoneais/efeitos dos fármacos , Nitratos/farmacologia , Óxido Nítrico/biossíntese , Animais , Feminino , Glucanos/farmacologia , Masculino , Camundongos , Camundongos Endogâmicos BALB C , Nitratos/metabolismo , Óxido Nítrico/farmacologia , Proteínas Opsonizantes/farmacologia , Superóxidos/farmacologiaRESUMO
The capacity of macrophages from SCID and C.B-17 mice to kill Candida albicans via a nitric oxide (NO)-dependent pathway and the contribution of NO in resistance to mucosal candidiasis were assessed. In vitro, an inhibitor of NO synthase (NOS) reduced the candidacidal activity and nitrite-producing capacity of activated resident peritoneal macrophages from immunocompetent C.B-17 and immunodeficient SCID mice. In vivo, stomachs from gnotobiotic SCID mice that were colonized with a pure culture of C. albicans had low-grade infections and expressed inducible NOS (iNOS) mRNA. C. albicans-monoassociated SCID mice treated with an inhibitor of NOS had more severe orogastric candidiasis than controls. These data suggest that NO contributes to the candidacidal capacity of activated macrophages from C.B-17 and SCID mice and that NO synthesized by iNOS may contribute to the resistance of SCID mice to mucosal candidiasis.
Assuntos
Aminoácido Oxirredutases/biossíntese , Arginina/análogos & derivados , Candida albicans , Candidíase/imunologia , Mucosa Gástrica/microbiologia , Imunidade Inata , Macrófagos Peritoneais/imunologia , Óxido Nítrico/fisiologia , Aminoácido Oxirredutases/antagonistas & inibidores , Animais , Arginina/farmacologia , Candidíase/patologia , Células Cultivadas , Relação Dose-Resposta a Droga , Feminino , Mucosa Gástrica/patologia , Guanidinas/farmacologia , Interferon gama/farmacologia , Lipopolissacarídeos/farmacologia , Ativação de Macrófagos/efeitos dos fármacos , Macrófagos Peritoneais/efeitos dos fármacos , Macrófagos Peritoneais/microbiologia , Masculino , Camundongos , Camundongos SCID , Óxido Nítrico Sintase , Proteínas Recombinantes , ômega-N-MetilargininaRESUMO
Despite the prevalence of gamma delta T cells in mucosae that are typically colonized by Candida albicans, little is known of the possible role of these cells in resistance to candidiasis. A sharp increase in the number of gamma delta T cells and macrophages following intraperitoneal inoculation of mice with C. albicans led us to examine the role of these cells in the immune response to C. albicans. We show that the gamma delta T cells enhance macrophage nitric oxide (NO) production and anti-candida activity, in vitro. We also propose that the gamma delta T cells regulate macrophage function during candidiasis in vivo as well, because depletion of these cells abrogated inducible NO synthase expression in mucosae and enhanced murine susceptibility to candidiasis.
Assuntos
Candidíase Bucal/imunologia , Candidíase Vulvovaginal/imunologia , Óxido Nítrico/biossíntese , Receptores de Antígenos de Linfócitos T gama-delta , Subpopulações de Linfócitos T/metabolismo , Animais , Sequência de Bases , Candidíase , Feminino , Vida Livre de Germes , Imunidade Inata , Hospedeiro Imunocomprometido , Interferon gama/farmacologia , Interferon gama/fisiologia , Depleção Linfocítica , Ativação de Macrófagos/efeitos dos fármacos , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Endogâmicos C57BL , Camundongos Nus , Dados de Sequência Molecular , Óxido Nítrico Sintase/biossíntese , Óxido Nítrico Sintase/genética , Proteínas Recombinantes , Organismos Livres de Patógenos Específicos , Subpopulações de Linfócitos T/imunologiaRESUMO
The candidacidal activity of neutrophils from BALB/c, C.B-17 +/+, C.B-17 scid/scid, scid/scid-bg/bg, C57BL/6 bg/+, C57BL/6 bg/bg, NIH III bg/bg-nu/+, and bg/bg-nu/nu mice was assessed. Killing of blastoconidia was moderately deficient with neutrophils from 2 strains of homozygous beige mice; however, neutrophils from all homozygous beige strains had a significantly decreased capacity to kill Candida albicans hyphae. This is the first demonstration of a decreased capacity of beige mouse neutrophils to kill C. albicans hyphae. The latter defect could be related to the enhanced susceptibility of beige mice to candidiasis.
Assuntos
Candida albicans/imunologia , Síndromes de Imunodeficiência/imunologia , Neutrófilos/imunologia , Animais , Separação Celular , Citometria de Fluxo , Imunidade Celular , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Endogâmicos C57BL , Camundongos MutantesRESUMO
Some activated murine macrophages produced nitrite but were unable to kill Candida albicans. Furthermore, a nitric oxide (NO) generator inhibited C. albicans growth but was not candidacidal. Our results suggest that NO is candidastatic and that No is not directly involved but is associated with or induces other macrophage candidacidal mechanisms.