Postnatal development of metallophilic macrophages in the rat thymus.

Metallophilic macrophages (MMs) are a distinct cell type of the rodent thymus. Our previous research has focused on the morphological characteristics of MMs, as well as on the molecular mechanisms involved in the development and tissue positioning of these cells. However, the postnatal development of MMs has not been sufficiently studied. In the present study, we investigated the positioning of MMs in the rat thymus between postnatal day 0 (P0) and P30. On P0, MMs were evenly distributed all over the thymic tissue-that is, the cortex, cortico-medullary zone and medulla. From P0 to P15, the number of MMs in the thymic cortex significantly decreased, and after P15, this number did not change. Thus, the present study shows that on P15, MMs almost completely disappear from the thymic cortex and show their adult position in the cortico-medullary zone and in the medulla.

Respiratory nursing training in Croatia.

Nursing education in the Republic of Croatia is conducted at the secondary and higher education levels (post-secondary and tertiary). Croatian nursing education is in line with the recommendations of European Directives 2005/36/EC [1] and 2013/55/EU [2]. High school (secondary level) education lasts for 5 years; after graduation, students are awarded the title "general care nurse" [3].

The Role of Macrophage Migration Inhibitory Factor in the Function of Intestinal Barrier.

Macrophage migration inhibitory factor (MIF) is a multifunctional protein that is involved in the development of gut-related inflammation. To investigate the role of MIF in the function of the intestinal barrier, we have explored intestinal permeability and gut-associated immune response in MIF-deficient (MIF-KO) mice. The absence of MIF provoked impairment of tight and adherens epithelial junctions in the colon through the disturbance of E-cadherin, zonula occludens-1, occludin and claudin-2 expression, which lead to the increase of intestinal barrier permeability. In these circumstances the diversity and content of gut microbiota in MIF-KO mice was considerably different compared to wild type mice. This change in microbiota was accompanied by an increased intestinal IgA concentration and a higher production of pro-inflammatory cytokines TNF and IFN-γ in mesenteric lymph nodes of MIF-KO mice. The forced changes of microbiota executed by antibiotics prevented the "leakage" of the barrier in MIF-KO mice, probably through up-regulation of occludin expression and normalization of cellular pore diameters. In addition, cytokine secretion was normalized after the treatment with antibiotics. These results suggest that MIF participates in the maintenance of physiological microbiota diversity and immunosurveillance, which in turn enables the proper intestinal barrier function.

Lipopolysaccharide induces tumor necrosis factor receptor-1 independent relocation of lymphocytes from the red pulp of the mouse spleen.

It is well known that bacterial lipopolysaccharide (LPS) induces migration of several cellular populations within the spleen. However, there are no data about the impact of LPS on B and T lymphocytes present in the red pulp. Therefore, we used an experimental model in which we tested the effects of intravenously injected LPS on the molecular, cellular and structural changes of the spleen, with special reference to the red pulp lymphocytes. We discovered that LPS induced a massive relocation of B and T lymphocytes from the splenic red pulp, which was independent of the tumor necrosis factor receptor-1 signaling axis. Early after LPS treatment, quantitative real-time PCR analysis revealed the elevated levels of mRNA encoding numerous chemokines and proinflammatory cytokines (XCL1, CXCL9, CXCL10, CCL3, CCL4, CCL5, CCL17, CCL20, CCL22, TNFα and LTα) which affect the navigation and activities of B and T lymphocytes in the lymphoid tissues. An extreme increase in mRNA levels for CCL20 was detected in the white pulp of the LPS-treated mice. The CCL20-expressing cells were localized in the PALS. Some smaller CCL20-expressing cells were evenly dispersed in the B cell zone. Thus, our study provides new knowledge of how microbial products could be involved in shaping the structure of lymphatic organs.

Suppression of methionine-induced colon injury of young rats by cysteine and N-acetyl-L-cysteine.

Changes in the methionine metabolism can cause a state called hyperhomocysteinemia, inducing oxidative stress in the gut. The production of free radicals is important in the colon damage caused by methionine. This study aimed at evaluating the effect of the use of L-cysteine and N-acetyl-L-cysteine on the colon morphometry of young rats treated with methionine. A total number of 32 male rats were distributed in a randomized experimental design in 4 groups: control group treated with saline; methionine group; cysteine + methionine group, and N-acetyl-L-cysteine + methionine group. After 21 days of treatment, rats were sacrificed and the colon samples were taken for histological and biochemical analysis. Methionine load increased depth of crypts, the lamina muscularis mucosae thickness, the mucosal height, and the number of cells in lamina propria (p < 0.01). Combination of methionine with L-cysteine (C group) and with N-acetyl-L-cysteine (N group) reversed methionine effects. Methionine treatment increased the GPx activity and MDA concentration, while L-cysteine and N-acetyl-L-cysteine increased the catalase activity compared to methionine group. It was concluded that the use of L-cysteine and N-acetyl-L-cysteine was beneficial to decrease intestinal mucosal height and oxidative damage when methionine was used in combination with them.

Remodeling of extracellular matrix of the lamina propria in the uninvolved human rectal mucosa 10 and 20 cm away from the malignant tumor.

In recent years, it has been demonstrated that malignancy arises and advances through the molecular interplay between tumor cells and non-malignant elements of the tumor stroma, that is, fibroblasts and extracellular matrix. However, in contrast to the mounting evidence about the role of tumor stroma in the genesis and progression of the malignant disease, there are very few data regarding the uninvolved stromal tissue in the remote surrounding of the tumor. Using the objective morphometric approach in patients with adenocarcinoma, we demonstrate the remodeling of extracellular matrix of the lamina propria in the uninvolved rectal mucosa 10 and 20 cm away from the neoplasm. We show that the representation of basic extracellular matrix constituents (reticular and collagen fibers and ground substance) is decreased. Also, the diameter of empty spaces that appear within the extracellular matrix of the lamina propria is increased. These spaces do not represent the blood or lymphatic vessel elements. Very likely, they reflect the development of tissue edema in the remote, uninvolved lamina propria of the mucosa in patients with the malignant tumor of the rectum. We hypothesize that the remodeling of extracellular matrix in lamina propria of the rectal mucosa may increase its stiffness, modulating the mechano-signal transduction, and thus promote the progression of the malignant disease.

Aberrant tissue positioning of metallophilic macrophages in the thymus of XCL1-deficient mice.

Metallophilic macrophages hold a strategic position within the thymic tissue and play a considerable function in thymic physiology. The development and positioning of these cells within thymic tissue are regulated by complex molecular mechanisms involving different cytokine/chemokine axes. Herein, we studied the role of XCL1 signaling in these processes. We show that in the XCL1-deficient thymus numerous metallophilic macrophages are aberrantly positioned in the thymic cortex, instead of their normal location in the cortico-medullary zone. Still, these cells retain their normal appearance: very large size with prominent, ramifying cytoplasmic prolongations. This shows that XCL1 signaling is not involved in morphological development, but rather in correct positioning of metallophilic macrophages within the thymic tissue. In contrast to thymic metallophilic macrophages, the positioning of splenic marginal metallophilic macrophages is not affected by XCL1-deficiency.

Morphometric study of uninvolved rectal mucosa 10 cm and 20 cm away from the malignant tumor.

Recently, many details of the interplay between tumor cells and tumor-associated stromal elements leading to the progression of malignant disease were elucidated. In contrast, little is known about the role of uninvolved stromal tissue in the remote surrounding of the malignant tumor. Therefore, we performed a computer-aided morphometric study of rectal mucosa in samples taken 10 cm and 20 cm away from the malignant tumor during endoscopic examination of 23 patients older than 60 years. The samples of rectal mucosa from 10 healthy persons of corresponding age subjected to diagnostic rectoscopy during active screening for asymptomatic cancer were used as control. All structural elements of the rectal mucosa were studied and the number of nucleated cells in the lamina propria per 0.1 mm² of tissue was assessed. Our study revealed a reduced number of cells in the lamina propria of the rectal mucosa 10 cm and 20 cm away from the tumor lesion in both male and female patients. The decreased mucosal height and increased crypt number were registered in female patients 10 cm away from the tumor. The connective tissue of lamina propria showed a disorderly organization: the collagen fibers were frail, loosely arranged and signs of tissue edema were present. Small blood vessels and capillaries were much more frequently seen than in healthy tissue. Our results demonstrate the complex interactions between the cancer and remote mucosal tissue of the affected organ.