RESUMEN
BACKGROUND: Irritable bowel syndrome (IBS) is a functional gastrointestinal disorder associated with idiopathic colonic hypersensitivity (CHS). However, recent studies suggest that low-grade inflammation could underlie CHS in IBS. The pro-inflammatory mediator nerve growth factor (NGF) plays a key role in the sensitization of peripheral pain pathways and several studies have reported its contribution to visceral pain development. NGF modulates the expression of Acid-Sensing Ion Channels (ASICs), which are proton sensors involved in sensory neurons sensitization. This study examined the peripheral contribution of NGF and ASICs to IBS-like CHS induced by butyrate enemas in the rat colon. METHODS: Colorectal distension and immunohistochemical staining of sensory neurons were used to evaluate NGF and ASICs contribution to the development of butyrate-induced CHS. KEY RESULTS: Systemic injection of anti-NGF antibodies or the ASICs inhibitor amiloride prevented the development of butyrate-induced CHS. A significant increase in NGF and ASIC1a protein expression levels was observed in sensory neurons of rats displaying butyrate-induced CHS. This increase was specific of small- and medium-diameter L1 + S1 sensory neurons, where ASIC1a was co-expressed with NGF or trkA in CGRP-immunoreactive somas. ASIC1a was also overexpressed in retrogradely labeled colon sensory neurons. Interestingly, anti-NGF antibody administration prevented ASIC1a overexpression in sensory neurons of butyrate-treated rats. CONCLUSIONS & INFERENCES: Our data suggest that peripheral NGF and ASIC1a concomitantly contribute to the development of butyrate-induced CHS NGF-ASIC1a interplay may have a pivotal role in the sensitization of colonic sensory neurons and as such, could be considered as a potential new therapeutic target for IBS treatment.
Asunto(s)
Canales Iónicos Sensibles al Ácido/metabolismo , Ganglios Espinales/metabolismo , Hiperalgesia/etiología , Síndrome del Colon Irritable/metabolismo , Factor de Crecimiento Nervioso/metabolismo , Bloqueadores del Canal Iónico Sensible al Ácido/farmacología , Amilorida/farmacología , Animales , Modelos Animales de Enfermedad , Ganglios Espinales/efectos de los fármacos , Hiperalgesia/metabolismo , Hiperalgesia/fisiopatología , Síndrome del Colon Irritable/fisiopatología , Masculino , Factor de Crecimiento Nervioso/farmacología , Dimensión del Dolor , Ratas , Ratas Sprague-DawleyRESUMEN
BACKGROUND AND PURPOSE: Recent evidence indicates that carbon monoxide-releasing molecules (CO-RMs) exhibit potential anti-inflammatory properties. In the present study, we have investigated whether tricarbonyl dichloro ruthenium(II) dimer (CORM-2) can control the inflammatory response induced by cytokines in a human colonic epithelial cell line, Caco-2. EXPERIMENTAL APPROACH: Caco-2 cells were preincubated with CORM-2 for 30 minutes and then stimulated with interleukin (IL)-1beta, tumor necrosis factor-alpha and interferon-gamma for different times. Gene expression was analyzed by real-time PCR. Protein expression was investigated by Western blot and ELISA. Transcription factor activation was determined by the luciferase method. KEY RESULTS: We have shown that CORM-2 significantly decreased the mRNA expression of nitric oxide synthase-2 (NOS-2) and the production of nitrite, in Caco-2 cells stimulated with cytokines. IL-8, IL-6 and metalloproteinase-7 (MMP-7) mRNA and protein were also significantly reduced by CORM-2. Time-course and small interfering RNA studies suggest that inhibition of IL-6 plays a role in the regulation of MMP-7 expression by CORM-2. These effects of CORM-2 can be dependent on the modulation of nuclear factor-kappaB (NF-kappaB), activator protein-1, CCAT/enhancer binding protein and the phosphorylated forms of NF-kappaB inhibitory protein-alpha, c-Jun N-terminal protein kinase 1/2, p38 and extracellular signal-regulated kinase 1/2. CONCLUSIONS AND IMPLICATIONS: CORM-2 can regulate a number of genes relevant in intestinal inflammation and cancer progression. These findings provide new insights into the anti-inflammatory properties and potential applications of this class of compounds.
Asunto(s)
Antiinflamatorios/farmacología , Monóxido de Carbono/metabolismo , Citocinas/metabolismo , Células Epiteliales/efectos de los fármacos , Expresión Génica/efectos de los fármacos , Inflamación/prevención & control , Mucosa Intestinal/efectos de los fármacos , Compuestos Organometálicos/farmacología , Antiinflamatorios/metabolismo , Proteínas Potenciadoras de Unión a CCAAT/metabolismo , Células CACO-2 , Citocinas/farmacología , Relación Dosis-Respuesta a Droga , Células Epiteliales/metabolismo , Humanos , Proteínas I-kappa B/metabolismo , Inflamación/metabolismo , Interferón gamma/metabolismo , Interleucina-1beta/metabolismo , Interleucina-6/genética , Interleucina-6/metabolismo , Interleucina-8/genética , Interleucina-8/metabolismo , Mucosa Intestinal/metabolismo , Mucosa Intestinal/patología , Sistema de Señalización de MAP Quinasas/efectos de los fármacos , Metaloproteinasa 7 de la Matriz/genética , Metaloproteinasa 7 de la Matriz/metabolismo , Inhibidor NF-kappaB alfa , FN-kappa B/metabolismo , Óxido Nítrico Sintasa de Tipo II/genética , Óxido Nítrico Sintasa de Tipo II/metabolismo , Compuestos Organometálicos/metabolismo , Fosforilación , ARN Mensajero/metabolismo , Factores de Tiempo , Factor de Transcripción AP-1/metabolismo , Factor de Necrosis Tumoral alfa/metabolismoRESUMEN
Heme oxygenase-1 (HO-1) activity can inhibit inflammatory and immune responses. We have examined the influence of HO-1 induction on the established rat adjuvant arthritis model of chronic inflammation. Therapeutic administration of cobalt protoporphyrin IX (CoPP; 5 mg/kg/day i.p.) from day 17 to 23 significantly reduced the inflammatory response, with partial inhibition of hind paw edema and the production of some inflammatory mediators such as nitric oxide metabolites and tumor necrosis factor-alpha, although joint erosion was observed. Hemin administration (26 mg/kg/day i.p.) during the same time period was ineffective on these parameters. Western blot analysis of hind paw homogenates revealed a weaker induction of HO-1 by this compound in comparison with CoPP. Our data indicate that pharmacological HO-1 induction after the establishment of adjuvant arthritis partially reduced the inflammatory response but it was not sufficient to control joint erosion in our experimental conditions.