Increased expression of chemokine receptors CCR1 and CCR3 in nasal polyps: molecular basis for recruitment of the granulocyte infiltrate.

Inflammatory processes play an important role in the development of nasal polyps (NP), but the etiology and, to a high degree also, the pathogenesis of NP are not fully understood. The role of several cytokines and chemokines such as eotaxins, IL-4, IL-5, IL-6, IL-8, and RANTES has been reported in NP. Herewith, we investigated the expression and pattern of distribution of chemokine receptors CCR1 and CCR3 in nasal polyps. Immunohistochemical detection was carried out in frozen sections of biopsies from 22 NP and 18 nasal mucosa specimens in both the epithelial and stromal compartments. Fluorescence microscopy and computerized image analysis revealed a statistically significant increased number of CCR1 (45.2 ± 2.8 vs. 15.1 ± 1.9, p < 0.001)-positive as well as CCR3 (16.4 ± 1.4 vs. 9.7 ± 1.1, p < 0.001)-positive cells in the stroma of NP compared to nasal mucosa. In comparison to healthy nasal mucosa, increased positivity of CCR3 was detected in the epithelial compartment of NP. Our data suggest that increased expression of CCR1 and CCR3 chemokine receptors may, in accord with various chemokines, contribute to the pathogenesis of nasal polyposis by facilitating increased migration and prolonged accumulation of inflammatory cells, e.g., eosinophils, in the inflammatory infiltrate of NP.

Expression of IGF-1R and iNOS in nasal polyps; epithelial cell homeostasis and innate immune mechanisms in pathogenesis of nasal polyposis.

Nasal polyps (NP), edematous projections of nasal mucosa (NM), are characterized by an inflammatory cellular infiltrate, however, little is known about etiopathogenesis of NP. Both innate immune mechanisms leading to activation of NF-kappaB and homeostasis of epithelial cells were implicated in the pathogenesis of NP. In this study we investigated the expression of insulin-like growth factor-1 receptor (IGF-1R) and inducible nitric-oxide synthase (iNOS) in NP compared to healthy NM in both the epithelial and stromal compartments. Using immunohistochemistry, frozen tissue sections of NP from 18 patients, and mucosal biopsy specimens of the inferior turbinate from 17 subjects were stained for IGF-1R and iNOS markers. Fluorescence microscopy and computerized image analysis revealed low numbers of IGF-1R-positive cells in all specimens. However, substantially increased numbers of IGF-1R-positive cells were found in NP compared to NM both within the epithelium (1.63 vs. 0.43) and stroma (3.27 vs. 1.03). Positivity for iNOS was detected within the epithelium of NP compared with NM. Numbers of iNOS-positive single cells were highly increased in NP vs. NM in both epithelial (3.83 vs. 1.08) and stromal (4.96 vs. 2.67) compartments. An increased iNOS expression within the epithelial layer as well as increased number of iNOS- and IGF-1R-positive cells in NP was observed. This suggests that innate immune mechanism, and to a lesser extent also growth and homeostasis of epithelial cells, may play a role in formation of NP.

CD14 is expressed and released as soluble CD14 by human intestinal epithelial cells in vitro: lipopolysaccharide activation of epithelial cells revisited.

Human endothelial as well as epithelial cells were shown to respond to lipopolysaccharides (LPSs). However, the expression and release of CD14 by these so-called CD14-negative cells have not been studied in detail. We investigated three human intestinal epithelial cell lines (ECLs), SW-480, HT-29, and Caco-2, for their expression of CD14 and CD11c/CD18 as well as their responsiveness to endotoxins. Fluorescence-activated cell sorter analysis revealed no expression of CD11c/CD18, but there was low expression of membrane-bound CD14 on HT-29, Caco-2, and SW-480 ECLs. Both Western blotting and reverse transcription-PCR confirmed the CD14 positivity of all three intestinal ECLs. No substantial modulation of CD14 expression was achieved after 6, 8, 18, 24, and 48 h of cultivation with 10-fold serial dilutions of LPS ranging from 0.01 ng/ml to 100 microg/ml. Interestingly, soluble CD14 was found in the tissue culture supernatants of all three ECLs. Finally, only HT-29 and SW-480, and not Caco-2, cells responded to LPS exposure (range, 0.01 ng/ml to 100 microg/ml) by interleukin 8 release. Thus, we show that HT-29, SW-480, and Caco-2 human intestinal ECLs express membrane-bound CD14. As Caco-2 cells did not respond to LPS, these cell lines might be an interesting model for studying the receptor complex for LPS. The fact that human intestinal epithelial cells are capable not only of expression but also of release of soluble CD14 may have important implications in vivo, e.g., in shaping the interaction between the mucosal immune system and bacteria in the gut and/or in the pathogenesis of endotoxin shock.

Brush border enzyme activities in the small intestine after long-term gliadin feeding in animal models of human coeliac disease.

Coeliac disease is a human, genetically linked, disorder which develops in gluten-sensitive persons. The aim of this study was to investigate the effect of prolonged feeding of gliadin, a major fraction of gluten, on enzyme activities of enterocyte brush border membrane enzymes in rats, mice and pigs. Brush-border membranes were isolated from mucosal scrapings of the small intestine of 21-d-old rat pups hand-fed with formula milk diet, two-month-old nu/nu and +/+ BALB/c mice and two-month-old piglets fed three times a week starting at birth with high doses of gliadin. Activities of lactase, sucrase and dipeptidyl peptidase IV (DPP IV) were determined. Individual animal models differed in their response to gliadin feeding. In comparison with albumin fed controls the activities of DPP IV and lactase were decreased in rat pups, nu/nu BALB/c mice and piglets. DPP IV activity was mostly affected in the ileum of rats and piglets fed with gliadin starting at birth. On the other hand, lactase and sucrase activities of nu/nu BALB/c mice and piglets decreased to the largest extent in jejunum.

Essential fatty acid deficiency and bone fragility in rats.

This study demonstrates the effect of essential fatty acid deficiency on the postnatal skeletal development in the rat. Four groups (n = 10) of newborn Wistar rats were fed diets containing high and low proportions of essential fatty acids in the lipid fraction until day 16 after birth. Suckled littermates were used as controls. X-ray and histological studies showed the occurrence of multiple pathological fractures of the long bones in 1-month-old rats fed a diet deprived of essential fatty acids. No effect of high (51,000 IU/100 g diet) and low (5,100 IU/100 g diet) concentrations of vitamin D2 was observed in our experiment. Thus, these data suggest the importance of essential fatty acids for bone pathology in the rat.

The gut as a lymphoepithelial organ: the role of intestinal epithelial cells in mucosal immunity.

Mucosal surfaces covered by a layer of epithelial cells represent the largest and most critical interface between the organism and its environment. The barrier function of mucosal surfaces is performed by the epithelial layer and immune cells present in the mucosal compartment. As recently found, epithelial cells, apart from their participation in absorptive, digestive and secretory processes perform more than a passive barrier function and are directly involved in immune processes. Besides the well known role of epithelial cells in the transfer of polymeric immunoglobulins produced by lamina propria B lymphocytes to the luminal content of mucosals (secretory Igs), these cells were found to perform various other immunological functions, to interact with other cells of the immune system and to induce an efficient inflammatory response to microbial invasion: enzymic processing of dietary antigens, expression of class I and II MHC antigens, presentation of antigens to lymphocytes, expression of adhesive molecules mediating interaction with intraepithelial lymphocytes and components of extracellular matrix, production of cytokines and probable participation in extrathymic T cell development of intraepithelial lymphocytes. All these functions were suggested to influence substantially the mucosal immune system and its response. Under immunopathological conditions, e.g. during infections and inflammatory bowel and celiac diseases, both epithelial cells and intraepithelial lymphocytes participate substantially in inflammatory reactions. Moreover, enterocytes could become a target of mucosal immune factors. Mucosal immunosurveillance function is of crucial importance in various pathological conditions but especially in the case of the most frequent malignity occurring in the intestinal compartment, i.e. colorectal carcinoma. Proper understanding of the differentiation processes and functions of epithelial cells in interaction with other components of the mucosal immune system is therefore highly desirable.