Hypoxia inducible transcription factor (HIF-1) regulates CXCL13 expression: Clinical implications in pediatric non-Hodgkin's lymphoma

Background: Lymphomas are B and/or T cell clonal neoplasms in various states of differentiation, characteristically compromising lymph nodes. They are constituted by B and T lymphocytes that reach the node by chemokine-mediated recruitment including CXCL13. Hypoxia-inducible transcription factor (HIF-1α) plays a role in cellular adaptation to oxygen concentration changes. It also regulates expression of chemokines such as CXCL12, CCL20, and CCL5 as well as some of their receptors such as CCR7 and CXCR4. Methods: We performed in silico analysis of the CXCL13 promoter, pharmacologic modulation of HIF-1α activity and, using reporter plasmids, site-directed mutation and DNA-protein interaction analysis we analyzed the relation between HIF-1α activity and CXCL13 expression. Moreover, we did tissue microarray and immunohistochemistry to see the expression of HIF-1α and CXCL13. Results: This study detected three possible HIF-1α binding sites suggesting that this chemokine may be regulated by the CXCL13 transcription factor. We showed that CXCL13 expression is directly dependent, whereby an increase in HIF-1α activity increases CXCL13 expression and decreased HIF-1α activity in turn decreases CXCL13 expression. We proved that HIF-1α transcriptionally regulates the expression of CXCL13 in a direct manner. We established that HIF-1α and CXCL13 are greatly overexpressed in the most aggressive pediatric lymphomas. Conclusions: For the first time, this study showed that HIF-1α directly regulates transcriptional CXCL13 and that both proteins are overexpressed in the most aggressive forms of pediatric lymphoma. This suggests that they may play a significant role in the pathogenesis of pediatric non-Hodgkin's lymphoma.

Evaluación de la expresión del factor de transcripción Yin-Yang-1 y su asociación con TGF-β en un modelo murino de inflamación alérgica pulmonar con diferentes grados de severidad / Evaluation of the expression of the transcription factor Yin-Yang-1: association with TGF-β in a lung allergic inflammation in a mouse model with different severity grades

Introducción. El asma alérgica es una de las enfermedades más prevalecientes en la edad pediátrica. Los mecanismos implicados en este padecimiento no han sido esclarecidos totalmente. Se sabe que el factor de crecimiento transformante-beta (TGF-β) juega un papel muy importante en la fisiopatología de esta enfermedad y que la activación del factor de trascripción Yin-Yang-1 (YY1) induce un aumento en la expresión de esta citocina. El factor YY1 también regula la expresión de otras citocinas involucradas en el asma tales como la IL-4 y la IL-10. El objetivo de este trabajo fue evaluarla asociación entre YY1 y TGF-β en un modelo murino de inflamación alérgica pulmonar. Métodos. Se trabajó con un modelo murino de inflamación alérgica pulmonar con diferentes grados de severidad empleando ovalbúmina como alérgeno. Posteriormente se obtuvo el tejido pulmonar, que fue incluido en parafina, se construyó un microarreglo del tejido en un equipo semiautomático y, mediante inmunohistoquímica, se evaluó la expresión de YY1 y de TGF-β La densidad de la expresión se midió de manera cuantitativa por métodos computarizados. Resultados. Se observó inflamación alérgica pulmonar diferencial acorde con el grado de severidad del modelo; se observó el mismo patrón con la producción de moco. La expresión de ambas proteínas se correlacionó de manera directa con el grado de severidad de la inflamación alérgica pulmonar. Conclusiones. Los resultados obtenidos corroboran el papel que juegan ambas proteínas en la fisiopatología de la inflamación alérgica pulmonar.

Background. Allergic asthma is one of the most prevalent childhood diseases. This disease is characterized by airway inflammation and remodelling. The mechanisms implicated in the pathogenesis of this disease remain unclear. Several studies have shown that TGF-β plays an important role in the pathogenesis of asthma. In addition, the polymorphism of the TGF-β promoter region results in the overexpression of TGF-β via regulation of the transcription factor Yin-Yang-1 (YY1). It is has recently been demonstrated that YY1 may be involved in the pathogenesis of asthma by the regulation of IL-4 and IL-10. The aim of this study was to evaluate the association between the YY1 and TGF-β expression levels in a murine model of lung allergic inflammation. Methods. In this study we used a lung allergic inflammatory murine model with different severity degrees. Tissue microarray technology and immunohistochemistry were used to evaluate YY1 and TGF-p expression. The density expression was measured by quantitative methods using specific software. Results. Expression of both proteins correlated with the degrees of severity of lung allergic inflammation. A similar result was observed with mucus production. Conclusions. These results corroborate the role of YY1 and TGF-p in the pathogenesis of this disease.