RESUMEN
Dysregulated T cell responses in the intestine may lead to chronic bowel inflammation such as collagenous colitis (CC) and lymphocytic colitis (LC), together known as microscopic colitis (MC). Having demonstrated increased local T cell responses in the intestinal mucosa of MC patients, we investigated the recent thymic emigrants by measuring T cell receptor excision circle (TREC) levels in the colonic biopsies from CC (n = 8), LC (n = 5), and CC or LC patients in histopathological remission (CC-HR, n = 3) (LC-HR, n = 6), non-inflamed diarrhoea patients (n = 17), and controls (n = 10) by real-time PCR. We observed lower median TREC levels in both CC and LC patients as well as in LC-HR patients compared to controls. In contrast to MC patients, non-inflamed diarrhoea patients presented with enhanced TREC levels compared to controls. None of the recorded differences did, however, reach statistical significance. A trend towards increased relative expression of CD3 was noted in all MC subgroups examined and reached statistical significance in LC patients compared to controls. In conclusion, reduced TRECs level in the colonic mucosa, together with our previously demonstrated enhanced expression of Ki67(+) T cells, suggests local expansion of resident T lymphocytes in the inflamed mucosa of MC patients.
Asunto(s)
Colitis Linfocítica/patología , Inflamación/patología , Membrana Mucosa/metabolismo , Receptores de Antígenos de Linfocitos T alfa-beta/metabolismo , Receptores de Antígenos de Linfocitos T gamma-delta/metabolismo , Adulto , Anciano , Anciano de 80 o más Años , Biopsia , Proliferación Celular , Colitis Linfocítica/inmunología , Colitis Linfocítica/metabolismo , Colitis Microscópica/inmunología , Colitis Microscópica/patología , Colon/metabolismo , Colon/patología , Femenino , Humanos , Inflamación/inmunología , Inflamación/metabolismo , Masculino , Persona de Mediana Edad , Membrana Mucosa/patología , Receptores de Antígenos de Linfocitos T alfa-beta/inmunología , Receptores de Antígenos de Linfocitos T gamma-delta/inmunología , Linfocitos T/inmunología , Linfocitos T/metabolismoRESUMEN
BACKGROUND: Collagenous colitis (CC) and lymphocytic colitis (LC) are chronic inflammatory bowel disorders of unknown etiology. This study investigated phenotypic characteristics of the mucosal lymphocytes in CC and LC. METHODS: Lamina propria and intraepithelial lymphocytes (LPLs, IELs) isolated from mucosal biopsies from CC (n=7), LC (n=6), as well as LC or CC patients in histopathological remission, (LC-HR) (n=6) and CC-HR (n=4) and non-inflamed controls (n=10) were phenotypically characterized by four-color flow cytometry. RESULTS: The proportions of CD8(+) IELs were increased in CC and LC (p<0.01) compared to controls. Increased proportions of CD45RO(+)CD8(+) IELs and LPLs were observed in LC and even more in CC patients (p<0.01). Both CC (p<0.05) and LC patients had elevated proportions of CD4(+)8(+) IELs and LPLs compared to controls. The proportions of CD45RO(+) cells were increased in CD4(+)8(+) IELs and LPLs (p<0.05) in CC and LC patients compared to controls. Both CC (p<0.05) and LC patients had higher proportions of Ki67(+)CD8(+) IELs and LPLs compared to controls. In contrast, decreased proportions of CD4(+) LPLs were observed in CC and LC as well as CD4(+) IELs in LC compared to controls. Increased proportions of Ki67(+)CD4(+) IELs and LPLs (p<0.05) were observed in CC and LC patients. CC-HR but not LC-HR patients demonstrated normalized proportions of both IELs and LPLs compared to CC and LC patients respectively. CONCLUSION: LC and CC patients have differences in mucosal lymphocyte subsets, with increased proportions of Ki67(+) and CD45RO(+) CD8(+) and CD4(+)8(+) mucosal T cells.
Asunto(s)
Colitis Colagenosa/inmunología , Colitis Linfocítica/inmunología , Mucosa Intestinal/inmunología , Linfocitos T/química , Adulto , Anciano , Anciano de 80 o más Años , Antígenos CD4/análisis , Antígenos CD8/análisis , Linfocitos T CD8-positivos , Estudios de Casos y Controles , Proliferación Celular , Colitis Colagenosa/patología , Colitis Linfocítica/patología , Colitis Ulcerosa/inmunología , Femenino , Citometría de Flujo , Humanos , Mucosa Intestinal/patología , Antígeno Ki-67/análisis , Antígenos Comunes de Leucocito/análisis , Recuento de Linfocitos , Masculino , Persona de Mediana Edad , Fenotipo , Adulto JovenRESUMEN
Mice deficient for the G protein subunit Gαi2 spontaneously develop colitis, a chronic inflammatory disease associated with dysregulated T cell responses. We and others have previously demonstrated a thymic involution in these mice and an aberrant thymocyte dynamics. The Gαi2(-/-) mice have a dramatically reduced fraction of double positive thymocytes and an increased fraction of single positive (SP) thymocytes. In this study, we quantify a number of critical parameters in order to narrow down the underlying mechanisms that cause the dynamical changes of the thymocyte development in the Gαi2(-/-) mice. Our data suggest that the increased fraction of SP thymocytes results only from a decreased number of DP thymocytes, since the number of SP thymocytes in the Gαi2(-/-) mice is comparable to the control littermates. By measuring the frequency of T cell receptor excision circles (TRECs) in the thymocytes, we demonstrate that the number of cell divisions the Gαi2(-/-) SP thymocytes undergo is comparable to SP thymocytes from control littermates. In addition, our data show that the mature SP CD4(+) and CD8(+) thymocytes divide to the same extent before they egress from the thymus. By estimating the number of peripheral TREC(+) T lymphocytes and their death rate, we could calculate the daily egression of thymocytes. Gαi2(-/-) mice with no/mild and moderate colitis were found to have a slower export rate in comparison to the control littermates. The quantitative measurements in this study suggest a number of dynamical changes in the thymocyte development during the progression of colitis.
Asunto(s)
Colitis/metabolismo , Subunidad alfa de la Proteína de Unión al GTP Gi2 , Timocitos/metabolismo , Timo/metabolismo , Animales , Atrofia/genética , Atrofia/metabolismo , Atrofia/patología , Antígenos CD4/metabolismo , Antígenos CD8/metabolismo , Colitis/genética , Colitis/patología , Ratones , Ratones Noqueados , Timocitos/patología , Timo/patologíaRESUMEN
Galphai2-deficient mice, which spontaneously develop colitis, have previously been reported to have an increased frequency of mature, single positive thymocytes compared to wild-type mice. In this study we further characterized the intrathymic changes in these mice before and during overt colitis. Even before the onset of colitis, Galphai2(-/-) thymi weighed less and contained fewer thymocytes, and this was exacerbated with colitis development. Whereas precolitic Galphai2(-/-) mice had unchanged thymocyte density compared to Galphai2(+/-) mice of the same age, this was significantly decreased in mice with colitis. Thymic atrophy in Galphai2(-/-) mice involved mainly the cortex. Using a five-stage phenotypic characterization of thymocyte maturation based on expression of CD4, CD8, TCRalphabeta, CD69 and CD62L, we found that both precolitic and colitic Galphai2(-/-) mice had significantly increased frequencies of mature single-positive CD4(+) and CD8(+) medullary thymocytes, and significantly reduced frequencies and total numbers of immature CD4(+) CD8(+) double-positive thymocytes compared to Galphai2(+/-) mice. Furthermore, cortical and transitional precolitic Galphai2(-/-) thymocytes showed significantly reduced chemotactic migration towards CXCL12, and a trend towards reduced migration to CCL25, compared to wild-type thymocytes, a feature even more pronounced in colitic mice. This impaired chemotactic migration of Galphai2(-/-) thymocytes could not be reversed by increased chemokine concentrations. Galphai2(-/-) thymocytes also showed reduced expression of the CCL25 receptor CCR9, but not CXCR4, the receptor, for CXCL12. Finally, wild-type colonic lamina propria lymphocytes migrated in response to CXCL12, but not CCL25 and, as with thymocytes, the chemokine responsiveness was significantly reduced in Galphai2(-/-) mucosal lymphocytes.
Asunto(s)
Quimiotaxis de Leucocito/inmunología , Colitis/inmunología , Subunidad alfa de la Proteína de Unión al GTP Gi2/deficiencia , Subgrupos de Linfocitos T/inmunología , Timo/inmunología , Animales , Quimiocina CXCL12 , Quimiocinas/inmunología , Quimiocinas CXC/inmunología , Colitis/patología , Colon/inmunología , Modelos Animales de Enfermedad , Progresión de la Enfermedad , Femenino , Subunidad alfa de la Proteína de Unión al GTP Gi2/genética , Mucosa Intestinal/inmunología , Recuento de Linfocitos , Masculino , Ratones , Ratones Endogámicos C57BL , Ratones Noqueados , Tamaño de los Órganos , Receptores CCR , Receptores CXCR4/metabolismo , Receptores de Quimiocina/metabolismo , Timo/patologíaRESUMEN
Helicobacter pylori infection induces chronic inflammation in the gastric mucosa with a marked increase in the number of lymphoid follicles consisting of infiltrating B and T cells, neutrophils, dendritic cells (DC) and macrophages. It has been suggested that an accumulation of mature DC in the tissue, resulting from a failure of DC to migrate to lymph nodes, may contribute to this chronic inflammation. Migration of DC to lymph nodes is regulated by chemokine receptor CCR7, expressed on mature DC, and the CCR7 ligands CCL19 and CCL21. In this study we analysed the maturation, in vitro migration and cytokine production of human DC after stimulation with live H. pylori. For comparison, DC responses to non-pathogenic Escherichia coli bacteria were also evaluated. Stimulation with H. pylori induced maturation of DC, i.e. up-regulation of the chemokine receptors CCR7 and CXCR4 and the maturation markers HLA-DR, CD80 and CD86. The H. pylori-stimulated DC also induced CD4(+) T-cell proliferation. DC stimulated with H. pylori secreted significantly more interleukin (IL)-12 compared to DC stimulated with E. coli, while E. coli-stimulated DC secreted more IL-10. Despite low surface expression of CCR7 protein following stimulation with H. pylori compared to E. coli, the DC migrated equally well towards CCL19 after stimulation with both bacteria. Thus, we could not detect any failure in the migration of H. pylori stimulated DC in vitro that may contribute to chronic gastritis in vivo, and our results suggest that H. pylori induces maturation and migration of DC to lymph nodes where they promote T cell responses.