Collagenase-3 expression in periapical lesions: an immunohistochemical study

Collagenase-3 (matrix metalloproteinase-13) is a metalloproteinase (MMP) that is associated with bone lesions and exhibits variable expression patterns in odontogenic cysts; it may play a role in regulating focal proliferation and maturation of jaw cyst epithelium. We studied the localization, staining intensity and distribution of collagenase-3 in 13 periapical granulomas with epithelium, 16 periapical granulomas without epithelium and 10 radicular cysts using archived formalin fixed, paraffin embedded tissues. A monoclonal antibody against human collagenase-3 was used to evaluate its expression. Immunohistochemical staining intensities of collagenase-3 in all periapical lesions were (?), 4 (10%); (+), 1 (3%); (++), 22 (56%) and (+++), 12 (31%); differences were not statistically significant. Immunohistochemical distribution of collagenase-3 in epithelial cells was (?), 17 (44%); (+), 17 (44%); (++), 5 (13%); in fibroblasts it was (?), 8 (20%); (+), 23 (59%); (++), 8 (21%); in plasma cells it was (?), 7 (18%); (+), 22 (56%); (++), 10 (26%); in macrophages it was (?), 7 (18%); (+), and 15 (38%); and (++), 17 (44%). Statistically significant differences were found in epithelial cells (p = 0.00) and fibroblasts (p = 0.02), whereas differences were not statistically significant for plasma cells and macrophages. Collagenase-3 may play a role in the conversion of a periapical granuloma with epithelium to radicular cyst. MMP's influence not only epithelial rest cell migration, but also invasion of various stromal cells into granulomatous tissue.     

Immunohistochemical detection of Langerhans cells in dental granulomas and radicular cysts

Objective Dental granulomas (DGs) and radicular cysts (RCs) are chronic periapical lesions frequently involving the jaws. Langerhans cells (LCs) are dendritic cells responsible for the presentation of antigens to T lymphocytes. This study examined the expression of LCs in DG and RCs by immunohistochemical staining. Study Design Eighteen cases of DGs and 26 cases of RCs were analyzed using anti-CD1a marker. Results CD1a-labeled LCs were observed in 11.1% of DGs and in 69.2% of RCs, showing a significant correlation (P < 0.0001; Fisher’s test). In DGs, LCs were only observed in granulation tissue, showing discrete immunostaining density. In RCs, LCs exhibited both a round and a dendritic shape in all epithelial layers. Although a correlation was observed between immunostaining density and epithelial thickness, as well as between immunostaining and inflammatory intensity, the differences were not significant in radicular cysts. Conclusion Langerhans cells provide important insight into the immunopathogenesis of chronic periapical lesions.     

Lectin-binding patterns in epithelial lining of jaw cysts

Lectin-binding patterns were examined in epithelial walls of 65 jaw cysts (30 post-operative maxillary cysts: POMCs, 20 radicular and 15 follicular cysts), and characteristic lectin staining for each kind of jaw cysts is presented. Between squamous and columnar epithelia, the staining intensity of WGA, Con A and UEA-I was not different, but SBA bound more remarkably to squamous than to columnar epithelia. In both epithelia the outer layers did react more strongly with the lectins examined. Concerning odontogenic cysts, the lectin-binding affinities of outer and intermediate layer cells were nearly the same in both follicular and radicular cysts. Basal cells of radicular cyst walls were however, more markedly positive for lectin binding than of follicular cysts. Furthermore, basal cells of keratinized (RKSE 60 keratin-positive) epithelium were inferior to those of non-keratinized linings in the bindings. Lectin-binding patterns of metaplastic squamose epithelia of POMCs which were positive for RGE53-keratin (principally columnar epithelium-specific keratin) were similar to originally squamous linings of odontogenic cysts. Columnar linings of unusual radicular cysts were positively stained with SBA. By these results, lectin-binding sugar residues of the epithelium seem to be related to the epithelial morphology.     

Nuclear morphometric features of epithelial cells lining keratocysts

OBJECTIVE: To investigate the nuclear morphometric features of epithelial cells lining keratocysts and some other odontogenic cysts. STUDY DESIGN: All cases were selected from the archives of the Department of Pathology, Gülhane Military Medical Academy, as follows: 20 keratocysts and 10 dentigerous and 10 radicular cysts. Nuclear morphometric variables were measured on hematoxylin and eosin-stained histologic slides. Basal and intermediate cells of the epithelium were evaluated separately. Nuclei of the cells were outlined interactively and measured using a specially written macro program. Area, feret ratio (ratio of the longest nuclear axis to the shortest one) and circularity (F circle) of the nuclei were calculated. Additionally, nuclear densitometric analysis was performed on the keratocyst cases. RESULTS: The number of cells in the basal layer (cell density) was higher in keratocysts than in other cysts. The mean nuclear area of basal cells was smaller than of intermediate cells in both keratocysts and other cysts (P < .001). The feret ratio values revealed that basal cell nuclei of keratocysts were more ovoid as compared to those of other cysts (P < .001). Nuclear densitometric findings showed that the DNA indices of all keratocyst cases were close to 1.0, and the cells were considered diploid. CONCLUSION: Increased cell density, a more ovoid nuclear shape and more variation in the size of basal layer cell nuclei in keratocysts were helpful in differentiating these lesions from other odontogenic cysts.     

Toll-like receptor expression in normal ovary and ovarian tumors

Recent studies have implicated inflammation in the initiation and progression of ovarian cancer, though the mechanisms underlying this effect are still not clear. Toll-like receptors (TLRs) allow immune cells to recognize pathogens and to trigger inflammatory responses. Tumor cell expression of TLRs can promote inflammation and cell survival in the tumor microenvironment. Here we sought to characterize the expression of TLRs in normal human ovaries, benign and malignant ovarian tumors from patients, and in established ovarian tumor cell lines. We report that TLR2, TLR3, TLR4, and TLR5 are strongly expressed on the surface epithelium of normal ovaries. In contrast to previous studies of uterus and endocervix, we found no cyclic variation in TLR expression occurred in murine ovaries. TLR2, TLR3, TLR4, and TLR5 are expressed in benign conditions, epithelial tumors, and in ovarian cancer cell lines. Variable expression of TLR6 and TLR8 was seen in benign and malignant epithelium of some patients, while expression of TLR1, TLR7, and TLR9 was weak. Normal and malignant ovarian stroma were negative for TLR expression. Vascular endothelial cells, macrophages, and occasional fibroblasts in tumors were positive. Functional activity for TLRs was demonstrated by stimulation of cell lines with specific ligands and subsequent activation and translocation of NFκB and release of the proinflammatory cytokines interleukin-6 and CCL-2. These studies demonstrate expression of multiple TLRs in the epithelium of normal ovaries and in ovarian tumor cells, and may indicate a mechanism by which epithelial tumors manipulate inflammatory pathways to facilitate tumor progression.     

Langerhans cells in odontogenic tumours and cysts as detected by S-100 protein immunohistochemistry

Immunohistochemical demonstration of S-100 protein in Langerhans cells (LCs) was made in odontogenic epithelial tumours (71 cases), radicular cysts (40 cases), follicular cysts (28 cases), odontogenic keratocysts (11 cases), primordial cysts (7 cases) and fissual cysts (6 cases). With the use of polyclonal antiserum against S-100 protein, positive LCs, dendrical or irregular in shape were found in tumour or cystic epithelia, and sometimes in stromal connective tissue. Incidence of positive S-100 staining LCs was 11 cases out of 61 ameloblastomas, 22 cases out of 40 radicular cysts, 3 cases of 28 follicular cysts, and other lesions in both odontogenic tumours and cystic diseases lacked LCs. The cases with S-100 protein positive LCs were usually accompanied with a high degree of inflammatory infiltration in their lesions; on the contrary, the negative cases also generally lacked inflammatory responses.     

The Chlamydia muridarum-induced IFN-β response is TLR3-dependent in murine oviduct epithelial cells

Epithelial cells lining the murine genital tract act as sentinels for microbial infection, play a major role in the initiation of the early inflammatory response, and can secrete factors that modulate the adaptive immune response when infected with Chlamydia. C. muridarum-infected murine oviduct epithelial cells secrete the inflammatory cytokines IL-6 and GM-CSF in a TLR2-dependent manner. Further, C. muridarum infection induces IFN-β synthesis in the oviduct epithelial cells in a TRIF-dependent manner. Because murine oviduct epithelial cells express TLR3 but not TLRs 4, 7, 8, or 9, we hypothesized that TLR3 or an unknown TRIF-dependent pattern recognition receptor was the critical receptor for IFN-β production. To investigate the role of TLR3 in the Chlamydia-induced IFN-β response in oviduct epithelial cells, we used small interfering RNA, dominant-negative TLR3 mutants, and TLR3-deficient oviduct epithelial cells to show that the IFN-β secreted during C. muridarum infection requires a functional TLR3. Interestingly, we demonstrate that the TLR3 signaling pathway is not required for IFN-β synthesis in C. muridarum-infected macrophages, suggesting that there are alternate and redundant pathways to Chlamydia-induced IFN-β synthesis that seem to be dependent upon the cell type infected. Finally, because there is no obvious dsRNA molecule associated with Chlamydia infection, the requirement for TLR3 in Chlamydia-induced IFN-β synthesis in infected oviduct epithelial cells implicates a novel ligand that binds to and signals through TLR3.     

Microbial DNA induces a host defense reaction of human respiratory epithelial cells

Epithelial cells represent the initial site of bacterial colonization in the respiratory tract. TLR9 has been identified in B cells and CD 123(+) dendritic cells and found to be involved in the recognition of microbial DNA. It was the aim of the study to investigate the role of TLR9 in the host defense reactions of the respiratory epithelium. Respiratory epithelial cell lines (IHAEo(-), Calu-3) or fully differentiated primary human cells as air-liquid interface cultures were stimulated with bacterial DNA or synthetic oligonucleotides containing CpG motifs (CpG oligodeoxynucleotides). Expression of TLR9, cytokines, and human beta-defensin 2 was determined by quantitative RT-PCR or by ELISA. We found that TLR9 is expressed by respiratory epithelial cell lines and fully differentiated primary epithelial cells at low levels. Stimulation of the above-mentioned cells with bacterial DNA or CpG oligodeoxynucleotide resulted in an inflammatory reaction characterized by a dose-dependent up-regulation of cytokines (IL-6, IL-8) and human beta-defensin 2. Up-regulation of NF-kappaB in epithelial cells in response to the CpG motif containing DNA was inhibited by overexpression of a dominant negative form of MyD88. These results provide clear evidence that the human respiratory epithelium is capable of detecting microbial DNA by TLR9. The respiratory epithelium has an important function in triggering innate immune responses and therefore represents an interesting target for anti-inflammatory therapy.     

Site‐specific contribution of Toll‐like receptor 4 to intestinal homeostasis and inflammatory disease

Toll‐like receptor 4 (TLR4) is a highly conserved protein of innate immunity, responsible for the regulation and maintenance of homeostasis, as well as immune recognition of external and internal ligands. TLR4 is expressed on a variety of cell types throughout the gastrointestinal tract, including on epithelial and immune cell populations. In a healthy state, epithelial cell expression of TLR4 greatly assists in homeostasis by shaping the host microbiome, promoting immunoglobulin A production, and regulating follicle‐associated epithelium permeability. In contrast, immune cell expression of TLR4 in healthy states is primarily centred on the maturation of dendritic cells in response to stimuli, as well as adequately priming the adaptive immune system to fight infection and promote immune memory. Hence, in a healthy state, there is a clear distinction in the site‐specific roles of TLR4 expression. Similarly, recent research has indicated the importance of site‐specific TLR4 expression in inflammation and disease, particularly the impact of epithelial‐specific TLR4 on disease progression. However, the majority of evidence still remains ambiguous for cell‐specific observations, with many studies failing to provide the distinction of epithelial versus immune cell expression of TLR4, preventing specific mechanistic insight and greatly impacting the translation of results. The following review provides a critical overview of the current understanding of site‐specific TLR4 activity and its contribution to intestinal/immune homeostasis and inflammatory diseases.     

Toll-like receptor 2 is upregulated by hog confinement dust in an IL-6-dependent manner in the airway epithelium

Hog confinement workers are at high risk to develop chronic bronchitis as a result of their exposure to organic dust. Chronic bronchitis is characterized by inflammatory changes of the airway epithelium. A key mediator in inflammation is Toll-like receptor 2 (TLR2). We investigated the role of TLR2 in pulmonary inflammation induced by hog confinement dust. Normal human bronchial epithelial cells (NHBE) were grown in culture and exposed to hog confinement dust extract. Hog confinement dust upregulated airway epithelial cell TLR2 mRNA in a concentration- and time-dependent manner using real-time PCR. There was a similar increase in TLR2 protein at 48 h as shown by Western blot. TLR2 was upregulated on the surface of airway epithelial cells as shown by flow cytometry. A similar upregulation of pulmonary TLR2 mRNA and protein was shown in a murine model of hog confinement dust exposure. Hog confinement dust is known to stimulate epithelial cells to produce IL-6. To determine whether TLR2 expression was being regulated by IL-6, the production of IL-6 was blocked using an IL-6-neutralizing antibody. This resulted in attenuation of the dust-induced upregulation of TLR2. To further demonstrate the importance of IL-6 in the regulation of TLR2, NHBE were directly stimulated with recombinant human IL-6. IL-6 alone was able to upregulate TLR2 in airway epithelial cells. Hog confinement dust upregulates TLR2 in the airway epithelium through an IL-6-dependent mechanism.     

Mechanical Stretch Inhibits Lipopolysaccharide-induced Keratinocyte-derived Chemokine and Tissue Factor Expression While Increasing Procoagulant Activity in Murine Lung Epithelial Cells

Previous studies have shown that the innate immune stimulant LPS augments mechanical ventilation-induced pulmonary coagulation and inflammation. Whether these effects are mediated by alveolar epithelial cells is unclear. The alveolar epithelium is a key regulator of the innate immune reaction to pathogens and can modulate both intra-alveolar inflammation and coagulation through up-regulation of proinflammatory cytokines and tissue factor (TF), the principal initiator of the extrinsic coagulation pathway. We hypothesized that cyclic mechanical stretch (MS) potentiates LPS-mediated alveolar epithelial cell (MLE-12) expression of the chemokine keratinocyte-derived cytokine (KC) and TF. Contrary to our hypothesis, MS significantly decreased LPS-induced KC and TF mRNA and protein expression. Investigation into potential mechanisms showed that stretch significantly reduced LPS-induced surface expression of TLR4 that was not a result of increased degradation. Decreased cell surface TLR4 expression was concomitant with reduced LPS-mediated NF-κB activation. Immunofluorescence staining showed that cyclic MS markedly altered LPS-induced organization of actin filaments. In contrast to expression, MS significantly increased LPS-induced cell surface TF activity independent of calcium signaling. These findings suggest that cyclic MS of lung epithelial cells down-regulates LPS-mediated inflammatory and procoagulant expression by modulating actin organization and reducing cell surface TLR4 expression and signaling. However, because LPS-induced surface TF activity was enhanced by stretch, these data demonstrate differential pathways regulating TF expression and activity. Ultimately, loss of LPS responsiveness in the epithelium induced by MS could result in increased susceptibility of the lung to bacterial infections in the setting of mechanical ventilation.     

Profiles of eicosanoid production by superficial and proliferative colonic epithelial cells and sub-epithelial colonic tissue

The profile of cyclooxygenase and lipoxygenase products in normal rat colonic epithelium and subepithelium was examined. Colons were thoroughly perfused to eliminate contamination with blood. Two preparations of colonic epithelium were employed. The first consisted of intact colonic crypts and epithelial sheets. The second yielded single cell suspensions of superficial versus proliferative epithelial cells. Lipoxygenase product formation by colonic epithelium as measured by hydroxyeicosatetraenoic acid (HETE) and leukotriene B4 (LTB4) production (5-HETE greater than 12-HETE greater than 15-HETE greater than LTB4) accounted for 58% of the total colonic production of these moieties, whereas epithelium accounted for only 20% of total colonic protein. By contrast, prostaglandin (PG) E2 and PGF2 alpha production occurred predominantly (greater than 97%) in the subepithelial layers. The present studies also demonstrate markedly higher levels of accumulation of lipoxygenase products in proliferative versus superficial epithelial cells, whereas prostaglandin accumulation was greater in superficial cells. Previous studies have supported a role for lipoxygenase and cyclooxygenase products in the control of colonic secretion, inflammatory cell infiltration and proliferative activity. The present results raise the possibility that the striking differences in the sites of production of these products within the colon has functional implications.     

The role of Toll-like receptors in non-infectious lung injury

The role of Toll-like receptors （TLRs） in pathogen recognition has been expeditiously advanced in recent years. However, investigations into the function of TLRs in non-infectious tissue injury have just begun. Previously, we and others have demonstrated that fragmented hyaluronan （HA） accumulates during tissue injury. CD44 is required to clear HA during tissue injury, and impaired clearance of HA results in unremitting inflammation. Additionally, fragmented HA stimulates the expression of inflammatory genes by inflammatory cells at the injury site. Recently, we identified that HA fragments require both TLR2 and TLR4 to stimulate mouse macrophages to produce inflammatory chemokines and cytokines. In a non-infectious lung injury model, mice deficient in both TLR2 and TLR4 show an impaired transepithelial migration of inflammatory cells, increased tissue injury, elevated lung epithelial cell apoptosis, and decreased survival. Lung epithelial cell overexpression of high molecular mass HA protected mice against acute lung injury and apoptosis, in part through TLR-dependent basal activation of NF-κB. The exaggerated injury in TLR2 and TLR4 deficient mice appears to be due to impaired HA-TLR interactions on epithelial cells. These studies identify that host matrix component HA and TLR interactions provide signals that initiate inflammatory responses, maintain epithelial cell integrity, and promote recovery from acute lung injury.     

TRIF Mediates Toll-like Receptor 5-induced Signaling in Intestinal Epithelial Cells

Toll-like receptors (TLRs) associate with adaptor molecules (MyD88, Mal/TIRAP, TRAM, and TRIF) to mediate signaling of host-microbial interaction. For instance, TLR4 utilizes the combination of both Mal/TIRAP-MyD88 (MyD88-dependent pathway) and TRAM-TRIF (MyD88-independent pathway). However, TLR5, the specific receptor for flagellin, is known to utilize only MyD88 to elicit inflammatory responses, and an involvement of other adaptor molecules has not been suggested in TLR5-dependent signaling. Here, we found that TRIF is involved in mediating TLR5-induced nuclear factor κB (NFκB) and mitogen-activated protein kinases (MAPKs), specifically JNK1/2 and ERK1/2, activation in intestinal epithelial cells. TLR5 activation by flagellin permits the physical interaction between TLR5 and TRIF in human colonic epithelial cells (NCM460), whereas TLR5 does not interact with TRAM upon flagellin stimulation. Both primary intestinal epithelial cells from TRIF-KO mice and TRIF-silenced NCM460 cells significantly reduced flagellin-induced NFκB (p105 and p65), JNK1/2, and ERK1/2 activation compared with control cells. However, p38 activation by flagellin was preserved in these TRIF-deficient cells. TRIF-KO intestinal epithelial cells exhibited substantially reduced inflammatory cytokine (keratinocyte-derived cytokine, macrophage inflammatory protein 3α, and IL-6) expression upon flagellin, whereas control cells from TRIF-WT mice showed robust cytokine expression by flagellin. Compare with TRIF-WT mice, TRIF-KO mice were resistant to in vivo intestinal inflammatory responses: flagellin-mediated exacerbation of colonic inflammation and dextran sulfate sodium-induced experimental colitis. We conclude that in addition to MyD88, TRIF mediates TLR5-dependent responses and, thereby regulates inflammatory responses elicited by flagellin/TLR5 engagement. Our findings suggest an important role of TRIF in regulating host-microbial communication via TLR5 in the gut epithelium.     

Gross and histological characterization of endometrial tissues from SLA miniature pigs with cystic endometrial hyperplasia

Cystic endometrial hyperplasia (CEH) is a uterine disorder characterized by the formation of large numbers of cysts in the endometrium. The purpose of this study was to examine and characterize cell types in the endometrium associated with the cysts and uterine glands. No apparent histological differences between CEH-involved and normal uterine columnar epithelium were found. Endometrial glands in CEH-involved and normal uteri were lined with simple or ciliated columnar epithelial cells and surrounded by lamellar connective tissue. The cyst epithelium appeared to be stretched obliquely and compressed so that both the cells and nuclei were horizontally oriented relative to the cyst lumen and were surrounded by lamellar connective tissue. Electron microgaphs revealed an abnormally high number of mitochondria in the cystic cells as compared to normal glandular cells. In conclusion, CEH is characterized by the formation of cysts which develop from the uterine glandular tissue. Epithelial cells lining the glands appeared to be distorted, possibly in response to internal pressure from increased volume due to high metabolic activity, and/or no uterine luminal opening.     

Hsp72 induces inflammation and regulates cytokine production in airway epithelium through a TLR4- and NF-kappaB-dependent mechanism

Heat shock proteins are generally regarded as intracellular proteins acting as molecular chaperones; however, Hsp72 is also detected in the extracellular compartment. Hsp72 has been identified in the bronchoalveolar lavage fluid (BALF) of patients with acute lung injury. To address whether Hsp72 directly activated airway epithelium, human bronchial epithelial cells (16HBE14o-) were treated with recombinant Hsp72. Hsp72 induced a dose-dependent increase in IL-8 expression, which was inhibited by the NF-kappaB inhibitor parthenolide. Hsp72 induced activation of NF-kappaB, as evidenced by NF-kappaB trans-activation and by p65 RelA and p50 NF-kappaB1 binding to DNA. Endotoxin contamination of the Hsp72 preparation was not responsible for these effects. Next, BALB/c mice were challenged with a single intratracheal inhalation of Hsp72 and killed 4 h later. Hsp72 induced significant up-regulation of KC, TNF-alpha, neutrophil recruitment, and myeloperoxidase in the BALF. A similar challenge with Hsp72 in TLR4 mutant mice did not stimulate the inflammatory response, stressing the importance of TLR4 in Hsp72-mediated lung inflammation. Last, cultured mouse tracheal epithelial cells (MTEC) from BALB/c and TLR4 mutant and wild-type mice were treated ex vivo with Hsp72. Hsp72 induced a significant increase in KC expression from BALB/c and wild-type MTEC in an NF-kappaB-dependent manner; however, TLR4 mutant MTEC had minimal cytokine release. Taken together, these data suggest that Hsp72 is released and biologically active in the BALF and can regulate airway epithelial cell cytokine expression in a TLR4 and NF-kappaB-dependent mechanism.     

Mechanisms of inflammatory injury of renal tubular cells in a cellular model of pyelonephritis

Previously, we have assembled a cellular model of pyelonephritis which contains a primary culture of renal tubular epithelial cells, mononuclear leukocytes, and bacterial lysate or lipopolysaccharide. After cocultivation of renal cells with leukocytes and bacterial lysate, proinflammatory changes were observed in the renal cells, followed by nitrosative and oxidative stress and cell death. The interaction of bacterial antigens not only with leukocytes, but also with epithelial cells of the renal tubules, was partially mediated by signaling pathways involving Toll-like receptors (TLR2 and TLR4). Activation of these receptors led to increased levels of oxidative stress and synthesis of proinflammatory cytokines (TNF, IL-6, IL-1α) in the renal epithelium, while TLR4 blockade decreased the severity of these processes. Apart from the fact that activation of inflammatory signaling in response to bacterial antigens is observed directly in the renal cells, the presence of leukocytes significantly amplifies the inflammatory response as measured by the level of cytokines generated in the ensemble. In the presence of activated leukocytes, higher expression of TLR2 on the surface of renal cells was observed in response to exposure to bacterial components, which might explain the increased inflammatory response in the presence of leukocytes. The synthesis of IL-1α in the epithelial cells of the renal tubules in this inflammatory model leads to its accumulation in the nuclei, which has been reduced by the TLR4 antagonist polymyxin. TLR2 agonists also led to increased levels of IL-1α. The elevation in the content of IL-1α in nuclei was accompanied by increased acetylation of nuclear proteins, which has been reduced to control values after exposure to protective agents (Trolox, mitochondria-targeted antioxidant SkQR1 or LiCl). The high level of acetylation of histones is probably regulated by proinflammatory cytokines, and to some extent it is a marker of inflammation, which can indirectly be reduced by protective agents.     

Respiratory syncytial virus up-regulates TLR4 and sensitizes airway epithelial cells to endotoxin

Airway epithelial cells are unresponsive to endotoxin (lipopolysaccharide (LPS)) exposure under normal conditions. This study demonstrates that respiratory syncytial virus (RSV) infection results in increased sensitivity to this environmental exposure. Infection with RSV results in increased expression of Toll-like receptor (TLR) 4 mRNA, protein, and increased TLR4 membrane localization. This permits significantly enhanced LPS binding to the epithelial monolayer that is blocked by disruption of the Golgi. The increased TLR4 results in an LPS-induced inflammatory response as demonstrated by increased mitogen-activated protein (MAP) kinase activity, IL-8 production, and tumor necrosis factor alpha production. RSV infection also allowed for tumor necrosis factor alpha production subsequent to TLR4 cross-linking with an immobilized antibody. These data suggest that RSV infection sensitizes airway epithelium to a subsequent environmental exposure (LPS) by altered expression and membrane localization of TLR4. The increased interaction between airway epithelial cells and LPS has the potential to profoundly alter airway inflammation.     

Profiles of eicosanoid production by superficial and proliferative colonic epithelial cells and sub-epithelial colonic tissue

The profile of cyclooxygenase and lipoxygenase products in normal rat colonic epithelium and subepithelium was examined. Colons were thoroughly perfused to eliminate contamination with blood. Two preparations of colonic epithelium were employed. The first consisted of intact colonic crypts and epithelial sheets. The second yielded single cell suspension of superficial versus proliferative epithelial cells. Lipoxygenase product formation by colonic epithelium as measured by hydroxyeicosatetraenoic acid (HETE) and leukotriene B₄ (LTB₄) production (5-HETE> 12-HETE> 15-HETE> LTB₄) accounted for 58% of the total colonic production of these moieties, whereas epithelium accounted for only 20% of total colonic protein. By contrast, prostaglandin (PG)E₂ and PGF_2α production occurred predominantly (>97%) in the subepithelial layers. The present studies also demonstrate markedly higher levels of accumulation of lipoxygenase products in proliferative versus superficial epithelial cells, whereas prostaglandin accumulation was greater in superficial cells. Previous studies have supported a role for lipoxygenase products in the control of colonic secretion, inflammatory cell infiltration and proliferative activity. The present results raise the possibility that the striking differences in the sites of production of these products within the colon has functional implications.