Resumen El proceso de transición epitelio-mesénquima (TEM) permite que una célula epitelial, de manera temporal, adquiera un fenotipo mesenquimal como respuesta a un estímulo interno o externo. Este proceso se caracteriza por la activación y represión de genes involucrados en diferentes vías de señalización asociadas con migración, invasión, apoptosis, entre otros. En este proceso, la epigenética cumple un papel fundamental, pues comprende cuatro mecanismos: metilación de ADN, modificación covalente de histonas, ARN no codificantes (ARNnc) y complejos remodeladores de la cromatina, que regulan la expresión de un gen sin alterar su secuencia. En esta revisión de tema los autores describen los principales mecanismos epigenéticos involucrados en la regulación de la expresión de genes que se activan y reprimen a lo largo del proceso TEM.

Abstract The mesenchymal epithelial transition (MET) process allows a temporary epithelial cell to acquire a mesenchymal phenotype in response to an internal or external stimulus. This process is characterized by the activation and repression of genes involved in different signaling pathways associated with migration, invasion and apoptosis, among others. In this process epigenetics plays a fundamental role. Epigenetics comprises four mechanisms: DNA methylation, covalent modification of histones, non-coding RNAs (RNACs) and chromatin remodeling complexes, which regulate the expression of a gene without altering its sequence. In this topic review, the authors describe the main epigenetic mechanisms involved in the regulation of the expression of genes that are activated and repressed throughout the TEM process.

Resumen La criptococosis pulmonar con afectación endobronquial es una entidad rara tanto en pacientes inmunocompetentes como en aquellos inmunocomprometidos. Comúnmente, se manifiesta como una lesión endobronquial y los hallazgos radiológicos pueden ser confundidos con tuberculosis o neoplasias. El artículo describe un caso de criptococosis endobronquial con afectación del bronquio intermediario en un paciente inmunocompetente que consultó por disnea y hemoptisis. En la literatura sobre el tema se han documentado 28 casos adicionales de criptococosis pulmonar con afectación endobronquial.

Abstract Pulmonary cryptococcosis with endobronchial involvement is a rare entity, both in immunocompetent and immunocompromised patients. This entity most commonly manifests as an endobronchial mass lesion and radiological findings can be confused with tuberculosis or neoplasia. Herein, we report a case of endobronchial cryptococcosis involving the bronchus intermedius, in an immunocompetent patient that presented with dyspnea and hemoptysis. Review of the literature revealed 28 additional cases of pulmonary cryptococcosis with endobronchial involvement.

ABSTRACT Exposure to Pneumocystis jirovecii (P. jirovecii) can lead to a wide variety of presenting features ranging from colonization in immunocompetent patients with lung disease, to invasive infections in immunocompromised hosts. Colonization by this fungus in patients with chronic obstructive pulmonary disease (COPD) could be associated with higher rates of exacerbations and impaired lung function in these patients.Our objective was to determine whether colonization by P. jirovecii in patients with COPD is associated with increased exacerbations and deterioration of lung function.This was a prospective cohort study on patients with COPD. All participants meeting selection criteria underwent clinical and microbiological assessments and were then classified as colonized vs. non-colonized patients. Chi-squared tests were performed and multivariate logistic models were fitted in order to obtain risk ratios (RR) with 95% confidence intervals (CI).We documented a frequency of colonization by P. jirovecii of 32.3%. Most patients were categorized as having GOLD B and D COPD. The history of significant exacerbations in the last year, health status impairment (COPD Assesment Tool ≥10), airflow limitation (percent of post-bronchodilator FEV1), and BODEx score (≥5) were similar between groups. After a 52-week follow-up period, the rate of adjusted significant exacerbations did not differ between groups. However, a decrease in FEVI was found in both groups.

Resumen El virus de la inmunodeficiencia humana (VIH) continúa siendo un problema de salud pública mundial, a pesar de la introducción de la terapia antirretroviral y la profilaxis frente a patógenos oportunistas. El pulmón es uno de los órganos más afectados por condiciones tanto infecciosas como no infecciosas en el contexto de la enfermedad retroviral; sin embargo, la prevalencia de las enfermedades de las vías respiratorias ha cambiado en las últimas dos décadas, tanto local como globalmente, por lo que se decidió realizar una búsqueda de la literatura más reciente en las bases de datos Medline y SciELO, incluyendo revisiones de tema y estudios originales, con el objetivo de elaborar una descripción actualizada de las principales enfermedades pulmonares descritas en pacientes con VIH, desde los puntos de vista clínico, paraclínico, radiológico y broncoscópico.

Abstract Human immunodeficiency virus (HIV) remains a public health problem worldwide, despite the introduction of antiretroviral therapy and prophylaxis against opportunistic pathogens. The lung is one of the most affected organs by both infectious and non-infectious diseases in the context of HIV, however, the prevalence of respiratory tract diseases has changed over the past two decades, both locally and globally, therefore, the authors decided to conduct a search of the most recent literature on Medline and SciELO databases, including reviews and original studies, with the aim of elaborating an updated description of the main pulmonary diseases in patients with HIV, taking into account clinical, paraclinical, radiological and bronchoscopic aspects.