RESUMEN
Tertiary lymphoid tissue (TLT) is lymphoid tissue that forms in adult life as a result of chronic inflammation in a tissue or organ. TLT has been shown to form in a variety of chronic inflammatory diseases, though it is not clear if and how TLT develops in the inflamed colon during inflammatory bowel disease. Here, we show that TLT develops as newly formed lymphoid tissue in the colon following dextran sulphate sodium induced colitis in C57BL/6 mice, where it can be distinguished from the preexisting colonic patches and solitary intestinal lymphoid tissue. TLT in the inflamed colon develops following the expression of lymphoid tissue-inducing chemokines and adhesion molecules, such as CXCL13 and VCAM-1, respectively, which are produced by stromal organizer cells. Surprisingly, this process of TLT formation was independent of the lymphotoxin signaling pathway, but rather under neuronal control, as we demonstrate that selective surgical ablation of vagus nerve innervation inhibits CXCL13 expression and abrogates TLT formation without affecting colitis. Sympathetic neuron denervation does not affect TLT formation. Hence, we reveal that inflammation in the colon induces the formation of TLT, which is controlled by innervation through the vagus nerve.
Asunto(s)
Colitis/inmunología , Colon/inervación , Tejido Linfoide/inervación , Estructuras Linfoides Terciarias/patología , Nervio Vago/patología , Animales , Quimiocina CXCL13/genética , Quimiocina CXCL13/metabolismo , Colitis/inducido químicamente , Colon/patología , Sulfato de Dextran , Femenino , Tejido Linfoide/patología , Linfotoxina-alfa/genética , Ratones , Ratones Endogámicos C57BL , Ratones Noqueados , Transducción de Señal , Molécula 1 de Adhesión Celular Vascular/metabolismoRESUMEN
The vitamin A metabolite retinoic acid (RA) has been reported to suppress Th1 responses and enhance Th2 responses. Here, we investigated whether differences in vitamin A metabolism could underlie the differences between C57BL/6 and BALB/c mice, which are reportedly seen as Th1 and Th2 responders, respectively. BALB/c mice were shown to have higher intestinal epithelial expression of RALDH1 (where RALDH is retinaldehyde dehydrogenase), and, consequently, higher RALDH activity in MLN-DCs, leading to an increased ability to induce IgA class switching in B cells. Furthermore, within BALB/c mice, induction of IgA secretion as well as increased accumulation of regulatory T cells (Treg) in the intestinal lamina propria was observed. Additionally, as BALB/c mice are more resistant to dextran sulphate sodium (DSS) induced colitis, mice that lacked vitamin A in their diet had a more severe form of DSS-induced colitis compared to control mice. Therefore, the level of RA production and consequently the degree of RA-mediated signaling is crucial for the efficiency of the mucosal immune system.
Asunto(s)
Colitis/inmunología , Inmunidad Mucosa , Intestinos/inmunología , Isoenzimas/inmunología , Membrana Mucosa/inmunología , Retinal-Deshidrogenasa/inmunología , Vitamina A/metabolismo , Familia de Aldehído Deshidrogenasa 1 , Animales , Colitis/inducido químicamente , Colitis/metabolismo , Colitis/patología , Sulfato de Dextran , Expresión Génica , Inmunoglobulina A/genética , Inmunoglobulina A/inmunología , Inmunoglobulina A/metabolismo , Cambio de Clase de Inmunoglobulina , Mucosa Intestinal/metabolismo , Intestinos/patología , Isoenzimas/genética , Isoenzimas/metabolismo , Ratones , Ratones Endogámicos BALB C , Ratones Endogámicos C57BL , Membrana Mucosa/metabolismo , Membrana Mucosa/patología , Retinal-Deshidrogenasa/genética , Retinal-Deshidrogenasa/metabolismo , Transducción de Señal , Especificidad de la Especie , Linfocitos T Reguladores/inmunología , Linfocitos T Reguladores/metabolismo , Linfocitos T Reguladores/patología , Células TH1/inmunología , Células TH1/metabolismo , Células TH1/patología , Células Th2/inmunología , Células Th2/metabolismo , Células Th2/patología , Vitamina A/administración & dosificaciónRESUMEN
BACKGROUND: Postoperative ileus is characterized by a transient impairment of the gastrointestinal motility after abdominal surgery. The intestinal inflammation, triggered by handling of the intestine, is the main factor responsible for the prolonged dysmotility of the gastrointestinal tract. Secondary lymphoid organs of the intestine were identified as essential components in the dissemination of inflammation to the entire gastrointestinal tract also called field effect. The involvement of the spleen, however, remains unclear. AIM: In this study, we investigated whether the spleen responds to manipulation of the intestine and participates in the intestinal inflammation underlying postoperative ileus. METHODS: Mice underwent Laparotomy (L) or Laparotomy followed by Intestinal Manipulation (IM). Twenty-four hours later, intestinal and colonic inflammation was assessed by QPCR and measurement of the intestinal transit was performed. Analysis of homeostatic chemokines in the spleen was performed by QPCR and splenic cell populations analysed by Flow Cytometry. Blockade of the egress of cells from the spleen was performed by administration of the Sphingosine-1-phosphate receptor 1 (S1P1) agonist CYM-5442 10 h after L/IM. RESULTS: A significant decrease in splenic weight and cellularity was observed in IM mice 24 h post-surgery, a phenomenon associated with a decreased splenic expression level of the homeostatic chemokine CCL19. Splenic denervation restored the expression of CCL19 and partially prevented the reduction of splenocytes in IM mice. Treatment with CYM-5442 prevented the egress of splenocytes but did not ameliorate the intestinal inflammation underlying postoperative ileus. CONCLUSIONS: Intestinal manipulation results in two distinct phenomena: local intestinal inflammation and a decrease in splenic cellularity. The splenic response relies on an alteration of cell trafficking in the spleen and is partially regulated by the splenic nerve. The spleen however does not participate in the intestinal inflammation during POI.
Asunto(s)
Ileus/cirugía , Inflamación/metabolismo , Intestinos/cirugía , Bazo/metabolismo , Animales , Modelos Animales de Enfermedad , Motilidad Gastrointestinal/efectos de los fármacos , Humanos , Ileus/fisiopatología , Indanos/administración & dosificación , Inflamación/patología , Inflamación/cirugía , Mucosa Intestinal/metabolismo , Intestinos/fisiopatología , Masculino , Ratones , Oxadiazoles/administración & dosificación , Complicaciones Posoperatorias/metabolismo , Complicaciones Posoperatorias/patología , Periodo Posoperatorio , Receptores de Lisoesfingolípidos/antagonistas & inhibidores , Bazo/efectos de los fármacosRESUMEN
CD169-positive macrophages in the marginal zone of the spleen and subcapsular sinus of lymph nodes play an important role as gatekeepers, strategically located to capture pathogens. Here we identified a population of CD169-positive macrophages in the colon and investigated which factors influenced their development. Murine colonic CD115+ F4/80(lo) CD11c(lo) macrophages expressing CD169 were present in the lamina propria, mainly surrounding the crypts. In spite of the high levels of bacterial flora in the colon and the importance of Toll-like receptor signalling in mucosal homeostasis, the presence of CD169+ macrophages was not affected in mice that were deficient in MyD88-mediated Toll-like receptor signalling and in mice in which the bacterial flora was eradicated. Whereas the development of splenic CD169+ macrophages was dependent on lymphotoxin α, colonic CD169+ macrophages were present in normal numbers in lymphotoxin α-deficient mice. In contrast, reduced numbers of CD169+ macrophages were found in the colon of mice deficient in vitamin A, whereas CD169+ macrophages in the spleen were unaffected. In conclusion, we identified a new macrophage subset in the lamina propria of the colon characterized by the expression of CD169. Its differentiation, unlike CD169+ macrophages in lymphoid organs, is independent of lymphotoxin α signalling, but requires vitamin A.
Asunto(s)
Colon/citología , Colon/inmunología , Macrófagos/citología , Macrófagos/inmunología , Mielopoyesis , Lectina 1 Similar a Ig de Unión al Ácido Siálico/inmunología , Animales , Colon/microbiología , Femenino , Linfotoxina-alfa , Ratones , Ratones Endogámicos C57BL , Ratones Noqueados , Membrana Mucosa/citología , Membrana Mucosa/inmunología , Vitamina A/metabolismoRESUMEN
Vagal nerve efferent activation has been shown to ameliorate the course of many inflammatory disease states. This neuro-modulatory effect has been suggested to rest on acetylcholine receptor (AChR) activation on tissue macrophages or dendritic cells (DCs). In more recent studies, vagal anti-inflammatory activity was shown involve adrenergic, splenic, pathways. Here we provide evidence that the adrenergic, rather than cholinergic, receptor activation on bone marrow derived DCs results in enhanced endocytosis uptake, enhanced IL-10 production but a decreased IL-6, IL-12p70 and IL-23 production. In antigen specific T cell stimulation assays, adrenergic ß2 receptor activation on bone marrow DCs led to an enhanced potential to induce Foxp3 positive suppressive Treg cells. These effects were independent of IL10-R activation, TGFß release, or retinoic acid (RA) secretion. Hence, adrenergic receptor ß2 activation modulates DC function resulting in skewing towards anti-inflammatory T cell phenotypes.
Asunto(s)
Citocinas/metabolismo , Células Dendríticas/metabolismo , Mediadores de Inflamación/metabolismo , Receptores Adrenérgicos beta 2/metabolismo , Agonistas Adrenérgicos beta/farmacología , Albuterol/farmacología , Animales , Células de la Médula Ósea/efectos de los fármacos , Células de la Médula Ósea/metabolismo , Células Cultivadas , Células Dendríticas/efectos de los fármacos , Dextranos/farmacocinética , Endocitosis/efectos de los fármacos , Epinefrina/farmacología , Femenino , Citometría de Flujo , Fluoresceína-5-Isotiocianato/análogos & derivados , Fluoresceína-5-Isotiocianato/farmacocinética , Factores de Transcripción Forkhead/metabolismo , Interleucina-10/metabolismo , Interleucina-12/metabolismo , Interleucina-23/metabolismo , Interleucina-6/metabolismo , Ratones , Ratones Endogámicos C57BL , Receptores Adrenérgicos beta 2/genética , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa , Linfocitos T Reguladores/efectos de los fármacos , Linfocitos T Reguladores/metabolismoRESUMEN
The vitamin A metabolite retinoic acid (RA) plays a crucial role in mucosal immune responses. We demonstrate in this study that RA-producing retinaldehyde dehydrogenase (RALDH) enzymes are postnatally induced in mesenteric lymph node (MLN) dendritic cells (DCs) and MLN stromal cells. RALDH enzyme activity in lamina propria-derived CD103(+) MLN-DCs did not depend on TLR signaling. Remarkably, RA itself could directly induce RALDH2 in both DCs and stromal cells in vitro. Furthermore, upon provision of a vitamin A-deficient diet, it was found that RA-mediated signaling was strongly reduced within the small intestines, while RALDH2 mRNA and RALDH enzyme activity in lamina propria DCs and MLN-DCs, as well as RALDH2 mRNA expression in MLN stromal cells, were strongly diminished. Moreover, supply of vitamin A to vitamin A-deficient mice restored RA-mediated signaling in the intestine and RALDH activity in lamina propria-derived CD103(+) MLN-DCs. Our results show that RA-dependent signaling within the intestine is indispensable for RALDH activity in the draining MLN.
Asunto(s)
Aldehído Oxidorreductasas/biosíntesis , Regulación de la Expresión Génica/inmunología , Mucosa Intestinal/enzimología , Intestino Delgado/enzimología , Ganglios Linfáticos/enzimología , Retinal-Deshidrogenasa/biosíntesis , Tretinoina/fisiología , Vitamina A/fisiología , Aldehído Oxidorreductasas/genética , Aldehído Oxidorreductasas/fisiología , Alimentación Animal , Animales , Células Dendríticas/enzimología , Células Dendríticas/inmunología , Células Dendríticas/patología , Mucosa Intestinal/inmunología , Mucosa Intestinal/patología , Intestino Delgado/inmunología , Intestino Delgado/patología , Ganglios Linfáticos/inmunología , Ganglios Linfáticos/patología , Mesenterio/enzimología , Mesenterio/inmunología , Mesenterio/patología , Ratones , Retinal-Deshidrogenasa/genética , Retinal-Deshidrogenasa/fisiología , Células del Estroma/enzimología , Células del Estroma/inmunología , Células del Estroma/patología , Vitamina A/administración & dosificación , Deficiencia de Vitamina A/enzimología , Deficiencia de Vitamina A/inmunología , Deficiencia de Vitamina A/patologíaRESUMEN
Antigen presenting cells like dendritic cells (DC) are responsible for the initiation of adaptive immune responses via the T helper cells they activate. The type of T cell responses DC induce is dependent on the local immunological environment where antigen has been taken up. In the gut, resident DC are phenotypically and functionally shaped by epithelial and stromal cell derived signals, the cytokine microenvironment, and neuronal products. These factors can control the activation state of DC thereby inducing tolerance for food and commensal organisms or immunity against pathogenic microbes. The enteric nervous system (ENS) is increasingly recognized as an important regulatory factor in intestinal immune cell control. Neurotransmitters and neuropeptides like acetylcholine (ACh), norepinephrine (NE) and vasoactive intestinal peptide (VIP) are released by neurons of the ENS and can affect the function of DC and subsequent immune responses. The critical balance between tolerance and protective immunity is disrupted in inflammatory bowel disease, which results in an exaggerated immune response against commensal bacteria. In this review we discuss the effects of ACh, VIP, and NE on DC function. DC express various receptors for these neuron derived products and can alter DC co-stimulatory molecule expression, cytokine release and subsequent T cell activation in an anti-inflammatory fashion. Knowledge about these interactions will help find new drug targets and may facilitate the development of specific therapies for diseases like inflammatory bowel disease (IBD).
Asunto(s)
Sistema Nervioso Autónomo/fisiología , Células Dendríticas/fisiología , Intestinos/inmunología , Neuroinmunomodulación , Acetilcolina/fisiología , Animales , Diferenciación Celular , Sistema Nervioso Entérico/fisiología , Humanos , Inflamación/inmunología , Intestinos/citología , Intestinos/inervación , Norepinefrina/fisiología , Sistema Nervioso Parasimpático/fisiología , Transducción de Señal , Sistema Nervioso Simpático/fisiología , Linfocitos T/citología , Linfocitos T/fisiología , Péptido Intestinal Vasoactivo/fisiologíaRESUMEN
The location of embryonic lymph node development is determined by the initial clustering of lymphoid tissue-inducer (LTi) cells. Here we demonstrate that both the chemokine CXCL13 and the chemokine CCL21 attracted LTi cells at embryonic days 12.5-14.5 and that initial clustering depended exclusively on CXCL13. Retinoic acid (RA) induced early CXCL13 expression in stromal organizer cells independently of lymphotoxin signaling. Notably, neurons adjacent to the lymph node anlagen expressed enzymes essential for RA synthesis. Furthermore, stimulation of parasymphathetic neural output in adults led to RA receptor (RAR)-dependent induction of CXCL13 in the gut. Therefore, our data show that the initiation of lymph node development is controlled by RA-mediated expression of CXCL13 and suggest that RA may be provided by adjacent neurons.
Asunto(s)
Quimiocina CXCL13/metabolismo , Ganglios Linfáticos/embriología , Neuronas/metabolismo , Tretinoina/metabolismo , Aldehído Deshidrogenasa/metabolismo , Familia de Aldehído Deshidrogenasa 1 , Animales , Diferenciación Celular , Movimiento Celular , Células Cultivadas , Quimiocina CCL21/metabolismo , Embrión de Mamíferos/embriología , Femenino , Isoenzimas/metabolismo , Tejido Linfoide/embriología , Ratones , Ratones Endogámicos BALB C , Ratones Noqueados , Retinal-Deshidrogenasa , Células del Estroma/metabolismo , Estimulación del Nervio VagoRESUMEN
UNLABELLED: Osteoporosis is a common complication of chronic liver disease, and the underlying mechanisms are not understood. We aimed to determine if osteoclasts develop from osteoclast precursors in peripheral blood mononuclear cells (PBMCs) of chronic liver disease patients with osteopenia compared with controls. PBMCs were isolated and fluorescence-activated cell sorting was performed to quantify the activated T lymphocyte population and receptor activator of nuclear factor kappabeta ligand (RANKL) expression. The activated T lymphocyte populations were comparable for all 3 groups, and RANKL was not detectable. The percentage of CD14+CD11b+ cells containing osteoclast precursors was comparable between the 3 groups. To assess the formation and functional activity of osteoclasts formed from circulating mononuclear cells, PBMCs were cultured (1) without addition of cytokines, (2) with macrophage colony-stimulating factor (M-CSF), (3) with M-CSF and osteoprotegerin, and (4) with M-CSF and RANKL. The number of tartrate-resistant acid phosphatase-positive multinucleated cells and bone resorption was assessed. PBMCs from chronic liver disease patients with osteopenia formed more osteoclast-like cells, which, when cultured in the presence of M-CSF and RANKL resorbed more bone than controls. The number of osteoclast-like cells and the amount of bone resorption correlated with lumbar bone densities. Addition of M-CSF increased numbers of osteoclast-like cells formed in healthy controls; however, this was not observed in either of the chronic liver disease groups. Plasma levels of M-CSF were elevated in both patient groups compared with healthy controls. CONCLUSION: Circulating mononuclear cells from chronic liver disease patients with osteopenia have a higher capacity to become osteoclasts than healthy controls or chronic liver disease patients without osteopenia. This could partially be due to priming with higher levels of M-CSF in the circulation.
Asunto(s)
Enfermedades Óseas Metabólicas/inmunología , Hepatopatías/inmunología , Osteoclastos/citología , Ligando RANK/metabolismo , Linfocitos T/metabolismo , Adolescente , Adulto , Anciano , Enfermedades Óseas Metabólicas/etiología , Enfermedades Óseas Metabólicas/metabolismo , Enfermedades Óseas Metabólicas/fisiopatología , Resorción Ósea/fisiopatología , Estudios de Casos y Controles , Diferenciación Celular/fisiología , Células Cultivadas , Enfermedad Crónica , Femenino , Humanos , Hepatopatías/complicaciones , Hepatopatías/metabolismo , Factor Estimulante de Colonias de Macrófagos/fisiología , Masculino , Persona de Mediana Edad , Reacción en Cadena de la Polimerasa de Transcriptasa InversaRESUMEN
The inference of transmission pathways for medicinally important bacteria is important to our understanding of pathogens. Here we report analyses of transmission in Helicobacter pylori, a major carcinogen. Our study is novel in that the focal community comprises detailed family pedigrees and has a high prevalence of H. pylori. To infer transmission, we performed high-resolution analyses of nucleotide sequences for three genes and accounted for the occurrence of mutation and recombination through the use of simulation modeling. Our results demonstrate that transmission has a strong nonfamilial component potentially the result of a large proportion of infections derived from the community. These results are interesting from both a medical and an evolutionary standpoint. First, efficient control measures and beliefs about the sources of H. pylori infection should be reevaluated. Evolutionarily, our results contradict the hypothesis of strict vertical transmission, presented as an explanation for the strong correlation between human population history and H. pylori diversity. Thus the paradox of persistent phylogenetic structure, despite a permissive mode of transmission and high recombination rates, must be solved elsewhere. Here we consider the potential for recombination events to maintain genetic structure in light of horizontal transmission.
Asunto(s)
Genética de Población , Infecciones por Helicobacter/transmisión , Helicobacter pylori/aislamiento & purificación , ADN Viral/genética , Transmisión de Enfermedad Infecciosa , Femenino , Infecciones por Helicobacter/diagnóstico , Infecciones por Helicobacter/epidemiología , Humanos , Masculino , Datos de Secuencia Molecular , LinajeRESUMEN
AIM: To study if T-cell activation related to portasystemic shunting causes osteoclast-mediated bone loss through RANKL-dependent pathways. We also investigated if T-cell inhibition using rapamycin would protect against bone loss in rats. METHODS: Portasystemic shunting was performed in male Sprague-Dawley rats and rapamycin 0.1 mg/kg was administered for 15 wk by gavage. Rats received powderized chow and supplemental feeds to prevent the effects of malnutrition on bone composition. Weight gain and growth was restored after surgery in shunted animals. At termination, biochemical parameters of bone turnover and quantitative bone histology were assessed. Markers of T-cell activation, inflammatory cytokine production, and RANKL-dependent pathways were measured. In addition, the roles of IGF-1 and hypogonadism were investigated. RESULTS: Portasystemic shunting caused low turnover osteoporosis that was RANKL independent. Bone resorbing cytokine levels, including IL-1, IL-6 and TNFalpha, were not increased in serum and TNFalpha and RANKL expression were not upregulated in PBMC. Portasystemic shunting increased the circulating CD8+ T-cell population. Rapamycin decreased the circulating CD8+ T-cell population, increased CD8+ CD25+ T-regulatory cell population and improved all parameters of bone turnover. CONCLUSION: Osteoporosis caused by portasystemic shunting may be partially ameliorated by rapamycin in the rat model of hepatic osteodystrophy.
Asunto(s)
Resorción Ósea/etiología , Resorción Ósea/fisiopatología , Proteínas Portadoras/metabolismo , Inmunosupresores/farmacología , Glicoproteínas de Membrana/metabolismo , Osteoclastos/efectos de los fármacos , Osteoporosis/prevención & control , Derivación Portosistémica Quirúrgica/efectos adversos , Sirolimus/farmacología , Animales , Índice de Masa Corporal , Densidad Ósea/fisiología , Resorción Ósea/patología , Linfocitos T CD8-positivos/efectos de los fármacos , Linfocitos T CD8-positivos/fisiología , Proteínas Portadoras/genética , Citocinas/sangre , Citocinas/metabolismo , Ingestión de Alimentos/fisiología , Regulación de la Expresión Génica , Activación de Linfocitos/efectos de los fármacos , Activación de Linfocitos/fisiología , Masculino , Glicoproteínas de Membrana/genética , Osteoclastos/patología , Osteoclastos/fisiología , Osteoporosis/etiología , Osteoporosis/metabolismo , Ligando RANK , Ratas , Ratas Sprague-Dawley , Factor de Necrosis Tumoral alfa/análisis , Factor de Necrosis Tumoral alfa/genética , Factor de Necrosis Tumoral alfa/metabolismoRESUMEN
Helicobacter pylori and Helicobacter felis are two of the Helicobacter spp. that infect humans. H. pylori has been linked to significant gastric pathology. Coinfection with Helicobacter spp. may influence infectious burden, pathogenesis, and antibiotic resistance; however, this has not been studied. The aims of this study were to identify the incidence of H. felis and to analyze the effects of coinfection with both organisms on gastric pathology in a well-characterized South African population. Biopsy samples from the gastric corpora and antra of volunteers (n = 90) were subjected to histological examination and PCR for the identification of H. pylori and H. felis. We further investigated the effect of global strain type on the occurrence of precursor lesions by assigning nucleotide sequences derived from PCR amplification of three genes to global groupings (ancestral Africa1, ancestral Africa2, ancestral Europe, ancestral Asia, and mixed). H. pylori was detected in 75 (83.3%), H. felis in 23 (25.6%), and coinfection in 21 (23.3%) of the volunteers by PCR. H. felis was randomly distributed among adults and children but clustered within families, suggesting intrafamilial transmission. Analysis of histopathology scores revealed no differences in atrophy, activity, and helicobacter density between H. felis-positive and H. felis-negative volunteers. H. pylori substrains common to southern Africa showed no differences in inflammation or atrophy scores. The incidences of H. felis and coinfection with H. pylori in the African population are high. H. felis infection, however, does not influence specific gastric pathology in this population.
Asunto(s)
Mucosa Gástrica/patología , Infecciones por Helicobacter/microbiología , Infecciones por Helicobacter/patología , Helicobacter felis , Helicobacter pylori , Adolescente , Adulto , Proteínas Bacterianas/genética , Secuencia de Bases , Niño , Preescolar , ADN Bacteriano/genética , Femenino , Genes Bacterianos , Infecciones por Helicobacter/epidemiología , Infecciones por Helicobacter/transmisión , Helicobacter felis/genética , Helicobacter felis/aislamiento & purificación , Helicobacter felis/patogenicidad , Helicobacter pylori/genética , Helicobacter pylori/aislamiento & purificación , Helicobacter pylori/patogenicidad , Humanos , Masculino , Proteínas de Transporte de Membrana/genética , Linaje , Sudáfrica/epidemiologíaRESUMEN
Our study aimed to evaluate the oral cavity as a reservoir from where Helicobacter pylori may be transmitted. Histology and PCR amplification were performed. Eighty-four percent of the stomach biopsies tested positive; however, H. pylori was not detected in dental samples, indicating the absence of H. pylori within the oral cavity.
Asunto(s)
Infecciones por Helicobacter/transmisión , Helicobacter pylori/aislamiento & purificación , Boca/microbiología , Población Rural , Adolescente , Adulto , Anciano , Biopsia , Niño , Preescolar , Placa Dental/microbiología , Femenino , Infecciones por Helicobacter/epidemiología , Infecciones por Helicobacter/microbiología , Humanos , Masculino , Persona de Mediana Edad , Reacción en Cadena de la Polimerasa/métodos , Prevalencia , Sudáfrica/epidemiología , Estómago/microbiologíaRESUMEN
UNLABELLED: The aims of this study were, first, to indicate the metabolic activity of hepatocytes in a radial-flow polyurethane foam matrix bioreactor relative to monocultures, and second, to evaluate the effect on the hepatocytes of including a synthetic perfluorocarbon (PFC) oxygen carrier to the recirculating medium. The efficient O2-carrying ability of PFCs may be beneficial to bioreactors employed in stressed cellular environments. Thus, they may also be useful in the treatment of an acute liver failure patient with a bioartificial liver support system (BALSS). Data on the function of three-dimensional (3-D) hepatocyte cultures exposed to emulsified PFCs are lacking. RESULTS: the metabolic functions of the 3-D hepatocyte cultures were improved relative to monocultures. Three-dimensional cultures with and without PFC behaved similarly, and no adverse effects could be detected when PFC was included in the recirculating medium. The addition of PFC significantly improved lidocaine clearance possibly due to the presence of higher O2 tension in the medium. Imaging indicated that large aggregates formed and that seeding had followed flow through the matrix. Simulations indicated first, that the cell numbers used in this study had been insufficient to challenge the bioreactor O2 supply explaining the similarity in performance of the 3-D cultures, and second, that the benefit of adding PFC would be more pronounced at the cell densities likely to be used in a BALSS bioreactor.