Glucocorticoid receptor mediates the expansion of splenic late erythroid progenitors during chronic psychological stress.

Stress evokes an integrated neuroendocrine response perturbing the homeostasis of different physiological systems. In contrast to well established physiologica linteractions between neuroendocrine and immune systems during chronic stress, there has been relatively little information on the effects of psychological stress on erythroid cells. Since stress-induced erythropoiesis occurs predominantly in the spleen, in the current study, we investigated the influence of chronic psychological stress on splenic erythroid progenitors and examined a role of glucocorticoid receptor (GR) in observed effect using a mouse model of restraint. The adult male mice were subjected to 2 hours daily restraint stress for 7 or 14 consecutive days and the role of GR in erythropoietic response to stress was assessed by pretreatment of mice with GR antagonist mifepristone 60 min prior to restraint. The results showed that chronic restraint stress induced an increase in spleen weight as well as in the cellularity of red pulp, as compared to controls. Furthermore, 7 and 14 days of restraint stress resulted in markedly increased number of both splenic early (BFU-E) and late (CFU-E) erythroid progenitors. Blockade of GR with mifepristone did not affect the number of BFU-E in stressed mice, but it completely abolished the effect of repeated psychological stress on CFU-E cells. Additionally, plasma corticosterone concentration was enhanced whereas the GR expression was significantly decreased within splenic red pulp after one and two weeks of stress exposure. Obtained findings suggest for the first time an indispensable role for GR in the expansion of CFU-E progenitors in the spleen under conditions of chronic psychological stress.

Large-cell neuroendocrine carcinoma of the ampulla of Vater.

Large-cell neuroendocrine carcinoma is a high-grade neuroendocrine carcinoma, originally described in the lung. The tumor rarely occurs in extrapulmonary sites like the gastrointestinal tract, and only few examples have been described in the ampulla of Vater. A new case of large-cell neuroendocrine carcinoma of the ampulla of Vater in a 60-year-old man is reported. After pancreatoduodenectomy, macroscopic examination revealed ulcerated tumor in the region of the ampulla of Vater. Microscopically, the tumor exhibited organoid, predominantly nested growth pattern, consisting of large, polygonal cells with pleomorphic nuclei. Average number of mitoses was 36 per 10 high-power fields. Small and large areas of necrosis were identified. Immunohistochemically, the tumor cells were positive for synaptophysin, chromogranin A, PGP 9.5, neuron-specific enolase, pancytokeratin, CK8 and somatostatin and negative for CK7, CK20, S-100, TTF-1, HMB-45, CD117, E-cadherin and regulatory peptides. Ki-67 proliferative index was 41%. Histone deacetylase (HDAC) analysis showed almost identical results for HDAC1, HDAC2 and HDAC3--60, 60.3 and 61%, respectively. Two months after surgery, liver metastases occurred, confirming highly aggressive behavior of large-cell neuroendocrine carcinoma.

Glucose-dependent insulinotropic polypeptide-producing K cells in dexamethasone-treated rats.

Some studies indicate that diabetes mellitus exerts an influence on the gastrointestinal tract and its diffuse neuroendocrine system (DNES) in regard to cellular density and neuroendocrine content. Since there is no data about relationship between experimentally induced non-insulin-dependent (type 2) diabetes mellitus (NIDDM) on the gut K cells, the aim of our study was to investigate immunohistochemical, stereological and ultrastructural changes of rat K cells after 12 days of dexamethasone treatment. Twenty male Wistar rats aged 30 days were given daily intraperitoneally 2 mg kg(-1) dexamethasone (group DEX, 10 rats) or saline (group C, 10 rats) for 12 days. Tissue specimens were obtained from each antrum with corpus and different parts of the small (SI) and large intestine (LI) of all animals. Immunohistochemistry was carried out using antisera against the GIP and insulin. Transmission electron microscopy was also used. Although, according to the literature data, rat K cells are present in the duodenum and jejunum and, to a lesser extent, in the ileum, in the present study we observed that those cells were abundant also in all parts of the LI. We observed generally that GIP-producing K cells were augmented in all parts of SI and decreased in the LI of DEX rats. Insulin immunoreactivity (ir) coexpressed with GIP-ir in K cells and was stronger in the SI of DEX rats as compared with C rats. We also found by electron microscopy that small intestinal K cells have features not only of GIP-secreted but also of insulin-secreted cells. We concluded that dexamethasone treatment caused proliferation of K cells in the rat SI, and simultaneously transformation of GIP-producing K cells to insulin-synthesizing cells.

[The role of endothelial cells in allergic inflammation reactions]. / Mesto i uloga celija endotela u reakcijama alergijske inflamacije.

Inflammatory response in tissue results from a complex network of interactions between inflammatory cells (mast cells, eosinophils, basophils, macrophages) and resident cells belonging to the lung structure (like endothelial cells, fibroblasts, epithelial cells). Among structural cells, endothelial cells play a critical role. The important role of endothelium is also reflected in the fact that it occupies an area exceeding 1000 m2. Thus, endothelium is the largest and the most active paracrine organ in the body, producing potent vasoactive, procoagulant, anticoagulant, and proinflammatory substances. Endothelial cells have four key functions that alter in the process of inflammation: 1 a) Regulation and control of leukocyte traffic through the expression of adhesion molecules (selectins E and P, molecules of immunoglobulin superfamily ICAM-1, ICAM-2, VCAM); 1 b) They are also able to amplify leukocyte activation through the production of proinflammatory cytokines like IL-1, IL-6 and chemokines like IL-8 and RANTES molecules; 2) Regulation of vascular tone by production of PGI-2, EDRF/NO and elements of local renin-angiotensin system; 3) Regulation of local coagulation by controlling the production of t-PA and PAI-1; 4) Regulation of the vascular permeability. In the states of acute inflammation, the endothelial cell takes on a proinflammatory phenotype and as such becomes chemoattractant, facilitating leukocyte adhesion, activation and migration, becomes prothrombotic and demonstrates enhanced vascular permeability.