The influence of dehydroepiandrosterone on effector functions of neutrophils

Dehydroepiandrosterone (DHEA) is a steroid hormone secreted by the adrenal glands, gonads and brain. It is a precursor to sex hormones and also is known to have immune modulatory activity. However, little is known about the relationship between DHEA and neutrophils and thus our study evaluates the influence of DHEA in the effector functions of neutrophils. Human neutrophils were treated in vitro with DHEA and further infected with Salmonella enterica serovar Typhimurium. The treatment of neutrophils with 0.01 µM of DHEA increased the phagocytosis of Salmonella independent of TLR4 as the treatment did not modulate the TLR4 expression. Additionally, DHEA caused a decrease in ROS (reactive oxygen species) production and did not influence the formation of the neutrophil extracellular trap (NET). Steroid treated neutrophils, infected or stimulated with LPS (lipopolysaccharide), showed reduced production of IL-8, compared to untreated cells. Also, the protein levels of p-NFκB were decreased in neutrophils treated with DHEA, and this reduction could explain the reduced levels of IL-8. These results led us to conclude that the steroid hormone DHEA has important modulatory functions in neutrophils

Relationships between phagocytosis, mucoid phenotype, and genetic characteristics of Klebsiella pneumoniae clinical isolates

Abstract INTRODUCTION The relationships between phagocytosis, and mucoid phenotype, plasmid profile and virulence, and resistance genetic characteristics of Klebsiella pneumoniae clinical isolates were evaluated. METHODS Thirty isolates were used to determine the mucoid aspect. Four were selected for analysis of phagocytosis by alveolar macrophages. RESULTS Thirty percent of the samples presented the mucoid phenotype. The phagocytosis rate ranged from 21.5% to 43.43%. Phagocytosis was not correlated with the plasmid profile, but was apparently correlated with mucoid phenotype and antibiotic susceptibility. CONCLUSIONS: Several virulence factors act in parallel in K. pneumoniae to impair host defense.

Síndrome de Roberts asociado con inmunodeficiencia / Roberts syndrome associated with immunodeficiency

El síndrome de Roberts es una enfermedad genética de transmisión autosómica recesiva extremadamente rara. Se caracteriza clínicamente por retardo pre y posnatal del crecimiento, acortamiento severo de los miembros con defectos radiales, oligodactilia y anomalías craneofaciales, causada por mutación en el gen ESCO2, el cual codifica para una acetiltransferasa involucrada en la regulación de la cohesión de las cromátides hermanas. Hasta donde se conoce, no se ha descrito en este síndrome ningún déficit del sistema inmunológico. Se presenta el caso de un niño de 1 año y medio de edad, con síndrome de Roberts, con procesos infecciosos recurrentes, algunos severos, desde el primer año de vida. En los estudios inmunológicos se observó disminución de los niveles de IgA, del número de linfocitos T CD3 positivos y de los CD4 positivos, con cuantificación normal de células B, así como alteración de la función opsonofagocítica. Se diagnosticó una inmunodeficiencia combinada asociada con un defecto de la fagocitosis. La identificación de una inmunodeficiencia asociada con este síndrome genético sugiere que corresponde con una enfermedad genéticamente heterogénea y la utilidad de la valoración inmunológica en los pacientes con defectos genéticos e infecciones recurrentes

Roberts syndrome is an extremely rare genetic disease of autosomal recessive. It is clinically characterized by pre and postnatal growth delaying, severe limb shortening, radial defects, oligodactyly, and craniofacial anomalies caused by mutation in the ESCO2 gene. This mutation encodes an acetyltransferase involved in regulating cohesion of sister chromatids. To our knowledge, no deficit of the immunological system has been described in this syndrome. We present here, a case of a one year and a half boy, with Roberts syndrome, recurrent infectious processes, some of them severe, since his first year of life. Immunological studies showed decreased levels of IgA, decreased number of CD3 positive T lymphocytes and decreased CD4 positive; they also showed cells with normal B quantification and opsonophagocytic function impairment. A combined immunodeficiency associated with defective phagocytosis was diagnosed. Identifying an immunodeficiency associated with this genetic syndrome suggests that it corresponds to a genetically heterogeneous disease. This also shows the usefulness of the immunological assessment in patients with genetic defects and recurrent infections

Differential gene expression profiles of human monocyte-derived antigen presenting cells in response to Penicillium marneffei: roles of DC-SIGN (CD209) in fungal cell uptake.

DNA microarray technology was used to determine the gene expression profile of human monocyte-derived macrophages (hMDMs) after stimulation by Penicillium marneffei yeast. The expression levels of 175 macrophage genes were found to be altered by a minimum of two-fold in magnitude following 4 hours of P. marneffei exposure. Among those, 41 genes were upregulated in activated hMDMs while 134 genes were downregulated. Real-time PCR and RT-PCR were performed to further examine gene expression associated with the inflammatory response. Increased levels of TNF-alpha and IL-1 beta gene expression in both hMDMs and human monocyte-derived dendritic cells (hMoDCs) were observed after stimulation by P. marneffei yeast. Furthermore, the genes encoding T-bet, IL-6 and ICAM-1 were also upregulated in hMDMs. Functional analysis of the adhesion of P. marneffei to dendritic cell-specific intercellular adhesion molecule-3 grabbing non-integrin (DC-SIGN, CD209) was performed in hMoDCs since the microarray data revealed an increased expression of DC-SIGN in activated hMDMs. We found that DC-SIGN-Fc bound preferentially to P. marneffei yeast rather than to conidia. Moreover, an anti-DC-SIGN monoclonal antibody inhibited the binding of P. marneffei yeast to hMoDCs, but did not inhibit endocytosis of P. marneffei yeast. The mannose receptor, on the other hand, was important in both adhesion and phagocytosis. These results suggest that P. marneffei may exploit DC-SIGN as a receptor to facilitate the systemic spread of infection. Taken together, our study demonstrates the usefulness of microarray technology in generating valuable expression data to permit conventional immunologic investigations of host-fungal interactions.

Keratocyte loss in Acanthamoeba keratitis: phagocytosis, necrosis or apoptosis?

PURPOSE: Pathogenesis of Acanthamoeba keratitis involves breakdown of epithelial barrier, stromal invasion by Acanthamoeba, loss of keratocytes, inflammatory response and finally stromal necrosis. The loss of keratocytes, believed to be due to the phagocytic activity of the parasite, occurs disproportionate to and independent of the parasite load, thereby suggesting additional modes of cell loss. To test our hypothesis that the loss of keratocytes in Acanthamoeba keratitis is due to apoptosis, we did both histology and histochemistry on the corneal tissues. METHODS: Routine Haematoxylin and Eosin, Gomori's Methenamine Silver and Periodic acid Schiff stained sections of five corneal tissues from penetrating keratoplasty and eviscerated eyes were reviewed. TUNEL staining was done for morphological detection of apoptosis in three cases, using formalin-fixed, paraffin-processed tissues. RESULTS: Histological changes were epithelial ulceration, loss of keratocytes in all layers, inflammation in anterior two-thirds of the stroma with necrosis, and deeper quiet stroma. Acanthamoeba trophozoites were found in the anterior stroma while the cysts were more in the deeper stroma, with minimal or no inflammatory response. TUNEL staining was positive in keratocytic nuclei in all layers. CONCLUSIONS: This study demonstrates that one of the modes of keratocyte loss in Acanthamoeba keratitis is by apoptosis, possibly in addition to the necrotic process and phagocytic activity of the parasite. The death of inflammatory cells also appears to be mediated by apoptosis.