Stable remission after administration of rituximab in a patient with primary hepatic marginal zone B-cell lymphoma.

We describe a case of primary hepatic marginal zone B-cell lymphoma in a 36-year-old Caucasian male with a history of chronic hepatitis B infection. Immunohistochemically, extensive infiltration by a CD20-positive, CD5- negative and CD10-negative lymphoid cell population displaying a follicular arrangement was detected. Molecular analysis of immunoglobulin heavy chain gene rearrangements confirmed the clonal expansion of lymphoma cells. Fourteen months after surgical treatment, the tumour recurred in close proximity to the liver hilus, hampering further surgery. Therefore, we implemented a therapy using the monoclonal anti-CD20-antibody rituximab in a dose of 375 mg/m(2), administered four times once a week. Six, 10, 18, and 26 months later the recurrent lymphoma could no longer be detected as shown by abdominal ultrasonography and CT. This case report demonstrates the difficulties of treating this extremely rare liver disease and shows its response to rituximab therapy.

Characterization of M cell formation and associated mononuclear cells during indomethacin-induced intestinal inflammation.

M cells represent an important gateway for the intestinal immune system by delivering luminal antigens through the follicle-associated epithelium to the underlying immune cells. The goal of this study was to characterize this route of antigen uptake during intestinal inflammation by characterizing M cell formation and M cell-associated lymphocytes after indomethacin challenge in rats. We demonstrated increased M cell formation as early as 12 h after a single injection of indomethacin. The elevated M cell counts were determined until day 3 and returned to basal levels after 7 days. Electron microscopic studies revealed an expansion of mononuclear cells inside the M cell pocket that were characterized predominantly as B cells, T cell receptor (TCR)alphabeta- and CD4-positive T cells, whereas other markers such as CD11b, CD8 and CD25 remained unchanged. In situ hybridization studies showed increased expression of interleukin (IL)-4 by lymphocytes during intestinal inflammation in the Peyer's patch follicle. These studies illuminate the relevance of M cells during intestinal inflammation and suggest that M cells derive from epithelial cells in a certain microenvironment.

Signet-ring cell carcinoma of unknown primary location. Metastatic to lower back musculature - remission following FU/FA chemotherapy.

The detection of gastrointestinal signet-ring cell carcinoma by endoscopy can be a diagnostic challenge. The main clinical features include atypical metastasis and a poor prognosis. We present a case of a metastasizing signet-ring cell carcinoma with unknown primary location arising in 71-year-old female. Following 6 cycles of a routine intravenous FU/FA chemotherapy, an almost complete remission could be observed. After 2 years of follow up, metastatic recurrence was detected to the lower back musculature. This case report emphasizes the difficulties in diagnosing signet-ring cell carcinoma by endoscopy and demonstrates an unusual clinical course.

Colorectal polyps: Detection with multi-slice CT colonography.

PURPOSE: To compare the performance of virtual and conventional colonoscopy for the detection of colorectal polyps using a multislice spiral CT scanner (MSCT). MATERIALS AND METHODS: 48 patients (20 women, 28 men, mean age 61.5 years) with clinical indication for conventional colonoscopy were prospectively studied using a MSCT (Somatom Volume Zoom, Siemens, Forchheim). Examination was performed after standard oral preparation for colonoscopy and colonic distension with room air and i. v. butylscopolamin. Images were obtained in prone and supine position using a detector configuration of 4 x 1 mm, a table feed of 5 mm/rotation at 140 mAs and 120 kV. Slice thickness and reconstruction increment were 3 and 1.5 mm, respectively. CT data were assessed by two blinded radiologists on a Vitrea workstation (Vital Images, USA) using a software with multiplanar and volume-rendering capabilities. RESULTS: 33 patients had normal findings on conventional colonoscopy. In 15 patients a total of 30 polyps and one carcinoma with stenosis were identified. MSCT-colonography identified the carcinoma and 23 polyps (77 %). 3 of 3 polyps were 10 mm or more (100 %), 6 of 7 were 5.1 to 9.9 mm (86 %) and 14 of 20 were 5 mm or smaller (70 %). There were 13 false positive findings for polyps (10 lesions < 6 mm in 5 patients) and no false positive finding of carcinoma. CONCLUSIONS: MSCT colonography allows accurate detection of polyps larger than 10 mm. Compared to published results of single-slice CT, multislice CT colonography increases the rate of detection of small colorectal polyps in particular. However, false positive results still remain a problem.

CD4+ Th1-cells predominate in low-grade B-cell lymphoma of gastric mucosa-associated lymphoid tissue (MALT type).

BACKGROUND: Little is known about the function of T cells in the inflammatory infiltrate in Helicobacter pylori-associated gastritis and B-cell lymphoma of mucosa-associated lymphoid tissue (MALT type). Previous studies have proposed a dominant Th1-type response in low-grade MALT lymphoma consistent with the Th1 response observed in H. pylori-associated gastritis. METHODS: We performed a novel flow cytometric approach in which CD3 panning for enrichment and activation of small numbers of T cells and intracellular cytokine analysis were combined to selectively characterize the cytokine profile of T cells (IFN-gamma for Th1) derived from the gastric mucosa of 23 patients with low-grade MALT lymphoma stage IEI1 (lymphoma infiltration of mucosa/submucosa sparing the muscularis). Endosonography was performed in each case to control the depth of lymphoma infiltration. For comparison, 19 patients with H. pylori-positive gastritis were also analysed. RESULTS: There was a CD4/CD8 ratio of 4 in patients with MALT lymphoma and of 2 in chronic gastritis. The proportion of IFN-gamma producing cells within the CD4-positive T-cell population in MALT lymphoma was 22%; in chronic gastritis it was 13% while no such difference could be encountered in CD8-positive T cells. CONCLUSIONS: The data point towards a dominant intratumoral IFN-gamma dominated T-cell response associated with early low-grade MALT lymphoma. A polarized IFN-gamma dominated Th1-type response may either contribute to the inability of the immune system to eradicate H. pylori infection, thereby promoting the activation status of the lymphocytic infiltrate in low-grade MALT lymphoma, or may mirror a concomitant tumor-specific T-cell response accompanying early stages of tumor progression.

Infliximab induces apoptosis in monocytes from patients with chronic active Crohn's disease by using a caspase-dependent pathway.

BACKGROUND & AIMS: Treatment with a chimeric anti-tumor necrosis factor (TNF) antibody (infliximab) has been shown to be highly efficient for patients with steroid-refractory Crohn's disease (CD). However, the mechanism of action remains largely unknown. As monocytopenia is commonly observed after treatment with infliximab, we investigated the role of infliximab-induced monocyte apoptosis. METHODS: Peripheral blood monocytes from healthy volunteers and patients with chronic active CD (CDAI > 250) were isolated by density gradient centrifugation methods. Apoptosis was determined by annexin V staining DNA-laddering, and transmission electron microscopy. Activation of caspases and mitochondrial release of cytochrome C was determined by immunoblotting. Transcriptional activation of members of the Bcl-2 family have been analyzed by ribonuclease protection assay. RESULTS: Treatment with infliximab at therapeutic concentrations resulted in monocyte apoptosis in patients with chronic active CD in a dose-dependent manner. Infliximab-induced monocyte-apoptosis required the activation of members of the caspase-family since activation of caspase-8, -9, and -3 could be determined. Caspase activation was induced by a CD95/CD95L independent signaling pathway with mitochondrial release of cytochrome C. Cytochrome C release seemed to be triggered by transcriptional activation of Bax and Bak. Monocyte apoptosis in vivo as determined by annexin-V binding and caspase-3 activation could be shown in patients with chronic active CD as soon as 4 hours after treatment with infliximab. CONCLUSIONS: Monocyte apoptosis induced by infliximab may be an important mechanism that could explain the powerful anti-inflammatory properties of infliximab in patients with chronic active CD.

Caspase activation correlates with the degree of inflammatory liver injury in chronic hepatitis C virus infection.

Hepatitis C virus (HCV) infection is a major cause of liver disease characterized by inflammation, cell damage, and fibrotic reactions of hepatocytes. Apoptosis has been implicated in the pathogenesis, although it is unclear whether proteases of the caspase family as the central executioners of apoptosis are involved and how caspase activation contributes to liver injury. In the present study, we measured the activation of effector caspases in liver biopsy specimens of patients with chronic HCV infection. The activation of caspase-3, caspase-7, and cleavage of poly(ADP-ribose)polymerase (PARP), a specific caspase substrate, were measured by immunohistochemistry and Western blot analysis by using antibodies that selectively detect the active truncated, but not the inactive precursor forms of the caspases and PARP. We found that caspase activation was considerably elevated in liver lobules of HCV patients in comparison to normal controls. Interestingly, the immunoreactive cells did yet not reveal an overt apoptotic morphology. The extent of caspase activation correlated significantly with the disease grade, i.e., necroinflammatory activity. In contrast, no correlation was observed with other surrogate markers such as serum transaminases and viral load. In biopsy specimens with low activity (grade 0) 7.7% of the hepatocytes revealed caspase-3 activation, whereas 20.9% of the cells stained positively in grade 3. Thus, our results suggest that caspase activation is involved in HCV-associated liver injury. Moreover, measurement of caspase activity may represent a reliable marker for the early detection of liver damage, which may open up new diagnostic and therapeutic strategies in HCV infection.

Impact of miniprobes compared to conventional endosonography in the staging of low-grade gastric malt lymphoma.

BACKGROUND AND STUDY AIMS: In patients with low-grade gastric MALT lymphoma, conventional endoscopic ultrasonography (EUS) is considered to be the most accurate modality for locoregional staging. The aim of this study was to evaluate the diagnostic role of ultrasonic miniprobes as part of routine clinical staging. PATIENTS AND METHODS: A total of 39 patients who were histologically diagnosed with low-grade MALT lymphoma were reviewed retrospectively before treatment (n = 15) and during follow-up (n = 24). Assessment of tumor penetration into the gastric wall was based on the TNM system. Pathological lymph-node involvement was suggested by the presence of inhomogeneous hypoechoic echo patterns, with clearly demarcated borders. All examinations were carried out using a mechanical miniprobe (Olympus; diameter 2.4 mm, 12 MHz) introduced through the working channel of the endoscope. Ultrasonic miniprobe findings were compared with conventional EUS data and histology. RESULTS: Using pretreatment endoscopic ultrasonography, gastric lymphomas presented endoscopically with an ulcer (in five of 15 patients) or a diffuse infiltrative pattern (ten of 15 patients). The ultrasonic miniprobe identified a T1 lesion in 53 % (T2, 33 %) and EUS in 60 % (T2, 20 %) of cases. Pathological lymph-node involvement in T1-T2 lesions was diagnosed with the ultrasonic miniprobe in 53 % of cases and with EUS in 60 %. Using endoscopic ultrasonography during the follow-up period, in patients with normal miniprobe ultrasonography (n = 15), the histological examination confirmed a complete remission in all patients. Hypoechoic thickening of the mucosa or submucosa, or both, was seen in nine patients. Endoscopic biopsies in four of these nine patients revealed recurrent lymphoma. CONCLUSIONS: The ultrasonic miniprobe can be recommended as part of routine care in patients with gastric MALT lymphoma, both initially and during the follow-up period. The clinical significance of ultrasonic miniprobe examinations is that they can be performed as a single-step procedure during diagnostic endoscopy.

Aspirin effects on gastric epithelial cell proliferation and cytokine expression.

Aspirin is known to cause gastric injury and to delay ulcer healing. The effects of aspirin on gastric epithelial cell function are heterogeneous; in contrast to injuring the mucosa, aspirin may also act beneficially by inducing adaptation; a mechanism that is poorly understood. We aimed to document the effects of different doses of aspirin on gastric epithelial cell function defined as proliferation, and secretion as well as mRNA expression of cytokines. Furthermore, we studied the effects of aspirin pretreatment on cytokine secretion as a potential element of gastric adaptation. The proliferative activity of three different gastric epithelial cell lines (AGS, KATO III, RGM-1) was assessed by (3)H-thymidine incorporation; secretion of growth factors PDGF-AB and VEGF into culture supernatant was documented by ELISA. mRNA transcripts of both cytokines were quantified by real time RT-PCR. Low doses of aspirin did not alter the proliferative dynamics in two of the three studied cell lines; high doses abolished proliferation. Secretion of PDGF-AB and VEGF increased during the first days of low dose aspirin exposition; higher concentrations led to a depletion of cytokines after an initial liberation in the case of VEGF, mRNA of which was also dose-dependently increased by aspirin. Seven-day pretreatment with low amounts of aspirin did not alter the secretory response of the epithelia caused by higher doses of this drug. The secretion of cytokines and proliferation of gastric epithelial cells are adversely effected by aspirin in a similarly dose-dependent fashion as the intended effects of this drug on platelet function and pain relief.

Regulated production of interferon-inducible T-cell chemoattractants by human intestinal epithelial cells.

BACKGROUND & AIMS: Human intestinal epithelial cells inducibly express neutrophil and monocyte chemoattractants, yet little is known about the regulated production of T-cell chemoattractants by the intestinal epithelium. IP-10, Mig, and I-TAC are 3 CXC chemokines that are known to act as CD4(+) T-cell chemoattractants. METHODS: We studied constitutive chemokine expression in human colon, and defined the regulated expression of these chemokines by reverse-transcription polymerase chain reaction, enzyme-linked immunosorbent assay, and immunohistology using cultured human intestinal epithelial cell lines and a novel adaptation of an in vivo human intestinal xenograft model. RESULTS: IP-10 and Mig were constitutively expressed by normal human colon epithelium, and their cognate receptor, CXCR3, was expressed by mucosal mononuclear cells. Interferon (IFN)-gamma stimulation increased mRNA expression and the polarized basolateral secretion of these chemokines by human colon epithelial cell lines; infection with enteroinvasive bacteria, or stimulation with the proinflammatory cytokines tumor necrosis factor alpha and interleukin 1alpha, strongly potentiated IFN-gamma-induced epithelial cell IP-10, Mig, and I-TAC production. Epithelial cell mRNA and protein expression of IP-10, Mig, and I-TAC were rapidly up-regulated in human intestinal xenografts in response to stimulation with IFN-gamma alone or in combination with IL-1. CONCLUSIONS: The constitutive and regulated production of the IFN-gamma-inducible chemokines IP-10, Mig, and I-TAC by human intestinal epithelium, and the expression of their cognate receptor, CXCR3, by mucosal mononuclear cells, suggest that the intestinal epithelium can play a role in modulating physiologic and pathologic T cell-mediated mucosal inflammation.

Patients with inflammatory bowel disease (IBD) reveal increased induction capacity of intracellular interferon-gamma (IFN-gamma) in peripheral CD8+ lymphocytes co-cultured with intestinal epithelial cells.

Intestinal epithelial cells seem to play a key role during IBD. The network of cellular interactions between epithelial cells and lamina propria mononuclear cells is still incompletely understood. In the following co-culture model we investigated the influence of intestinal epithelial cells on cytokine expression of T cytotoxic and T helper cells from patients with IBD and healthy controls. Peripheral blood mononuclear cells (PBMC) were purified by a Ficoll-Hypaque gradient followed by co-incubation with epithelial cells in multiwell cell culture insert plates in direct contact as well as separated by transwell filters. We used Caco-2 cells as well as freshly isolated colonic epithelia obtained from surgical specimens. Three-colour immunofluorescence flow cytometry was performed after collection, stimulation and staining of PBMC with anti-CD4, anti-CD8, anti-IFN-gamma and anti-IL-4. Patients with IBD (Crohn's disease (CD), n = 12; ulcerative colitis (UC), n = 16) and healthy controls (n = 10) were included in the study. After 24 h of co-incubation with Caco-2 cells we found a significant increase of IFN-gamma-producing CD8+ lymphocytes in patients with IBD. In contrast, healthy controls did not respond to the epithelial stimulus. No significant differences could be found between CD and UC or active and inactive disease. A significant increase of IFN-gamma+/CD8+ lymphocytes in patients with UC was also seen after direct co-incubation with primary cultures of colonic crypt cells. The observed epithelial-lymphocyte interaction seems to be MHC I-restricted. No significant epithelial cell-mediated effects on cytokine expression were detected in the PBMC CD4+ subsets. Patients with IBD-even in an inactive state of disease-exert an increased capacity for IFN-gamma induction in CD8+ lymphocytes mediated by intestinal epithelial cells. This mechanism may be important during chronic intestinal inflammation, as in the case of altered mucosal barrier function epithelial cells may become targets for IFN-gamma-producing CD8+ lymphocytes.

Role of the CD95/CD95 ligand system in glucocorticoid-induced monocyte apoptosis.

Glucocorticoids (GC) act as potent anti-inflammatory and immunosuppressive agents on a variety of immune cells. However, the exact mechanisms of their action are still unknown. Recently, we demonstrated that GC induce apoptosis in human peripheral blood monocytes. In the present study, we examined the signaling pathway in GC-induced apoptosis. Monocyte apoptosis was demonstrated by annexin V staining, DNA laddering, and electron microscopy. Apoptosis required the activation of caspases, as different caspase inhibitors prevented GC-induced cell death. In addition, the proteolytic activation of caspase-8 and caspase-3 was observed. In additional experiments, we determined the role of the death receptor CD95 in GC-induced apoptosis. CD95 and CD95 ligand (CD95L) were up-regulated in a dose- and time-dependent manner on the cell membrane and also released after treatment with GC. Costimulation with the GC receptor antagonist mifepristone diminished monocyte apoptosis as well as CD95/CD95L expression and subsequent caspase-8 and caspase-3 activation. In contrast, the caspase inhibitor N:-acetyl-Asp-Glu-Val-Asp-aldehyde suppressed caspase-3 activation and apoptosis, but did not down-regulate caspase-8 activation and expression of CD95 and CD95L. Importantly, GC-induced monocyte apoptosis was strongly abolished by a neutralizing CD95L mAb. Therefore, our data suggest that GC-induced monocyte apoptosis is at least partially mediated by an autocrine or paracrine pathway involving the CD95/CD95L system.

[Classic case of benign recurrent intrahepatic cholestasis (Summerskill-Halshe-Tygstrup syndrome)]. / Ein klassischer Fall der benignen rekurrierenden intrahepatischen Cholestase (Summerskill-Walshe-Tygstrup-Syndrom).

BACKGROUND: The benign recurrent intrahepatic cholestasis is an autosomal recessively inherited liver disease. The gene was mapped to a region on chromosome 18q21-22. Because of its rareness this disease is first considered in the differential diagnosis of cholestasis after many years of extensive investigations. CASE REPORT: We report about a 17-year-old patient, who suffered from intermittent attacks of cholestatic jaundice and pruritus. Clinical course, laboratory data and invasive investigations led to the diagnosis of a typical case of benign recurrent intrahepatic cholestasis (Summerskill-Walshe-Tygstrup syndrome). CONCLUSION: This disease is remarkable for a discrepancy between a rise of serum bile acids at the onset of each attack and a later rise of bilirubin. Typically high bilirubin levels are noted, and bilirubin can even reach more than 50 mg/dl. The serum alkaline phosphatase is increased, too, whereas the values for the transaminases and gamma GT are normal or only slightly elevated. Histological studies reveal a cholestasis, bile plugs in the bile canaliculi, a perilobular fibrosis and inflammatory infiltrations of the periportal zones. Differential diagnosis includes an abundance of diseases with cholestasis. Treatment is difficult, purely symptomatic and often without marked effect. Nevertheless prognosis is good, histories of about 50 years were without evidence of progression to cirrhosis.

IL-10 induces apoptosis in human monocytes involving the CD95 receptor/ligand pathway.

The cytokine IL-10 exerts potent immunosuppressive and anti-inflammatory effects, although the mechanisms of this action remain largely unknown. In the present study, we investigated the effects of IL-10 in human peripheral blood monocytes. We were able to demonstrate that IL-10 dose- and time-dependently triggers apoptosis in these cells as detected by annexin-V staining, the nick end labeling (TUNEL) procedure, electron microscopy and analysis of DNA laddering. IL-10-induced apoptosis required the activation of proteases of the caspase family, since a peptide caspase inhibitor attenuated cell death and, in addition, the proteolytic activation of caspase-8 was observed. Since caspase-8 has been implicated as a regulator of apoptosis mediated by death receptors, we investigated a potential involvement of the CD95 receptor/ligand system. Indeed, treatment of monocytes with IL-10 induced a dose-dependent up-regulation of CD95 receptor and ligand expression on the monocyte surface. Furthermore, a CD95 ligand-neutralizing antibody significantly inhibited IL-10-induced apoptosis. In summary, our data show that IL-10 triggers monocyte apoptosis involving the CD95 system via an autocrine or paracrine process. Therefore, at least part of the anti-inflammatory properties of IL-10 may involve induction of apoptosis in monocytes.

[Signet ring cell carcinoma of the stomach--a case of diagnostic dilemma]. / Siegelringzellkarzinom des Magens--ein Fall von diagnostischem Dilemma.

Inguinal lymphonodal metastases of an adenocarcinoma were diagnosed in a 40-year-old patient by ultrasound guided puncture. The leading symptom was elephantiasis preferentially of the right lower extremity. In addition, atypical mycobacteriosis was detected later on. The causal gastric cancer had not been identified during two years until the fourth gastroscopy assisted by endoscopic ultrasonography revealed the lesion. No regional lymph node metastases were found while distant metastases in terms of inguinal lymph nodes were already present.

Characterization of M cell development during indomethacin-induced ileitis in rats.

BACKGROUND: M cells play an important role in the intestinal immune system as they have a high capacity for transcytosis of a wide range of microorganisms and macromolecules. However, little is known about the role of M cells during intestinal inflammation. AIM: We studied M cell development during indomethacin-induced intestinal inflammation in rats. METHODS: Ileitis in rats was induced by two subcutaneous injections with indomethacin (7.5 mg/kg) given 24 h apart. Rats were sacrificed after 14 days and tissue was analysed by fluorescence microscopy and electron microscopy. M cells could be visualized by using the FITC-labelled mAb anti-cytokeratin (CK)-8 (clone 4.1.18), which was recently identified as specific M cell marker in rats. The number of cytokeratin-8 positive M cells was related to the surface of the follicle associated epithelium. For morphological studies, we used both transmission electron microscopy (T.E.M.) and scanning electron microscopy (S.E.M.). RESULTS: In non-inflamed ileum M cells were scarce. Only 4% of the follicle associated epithelium were M cells, whereas an increase of M cells up to 11% was found in inflamed follicle associated epithelium (P < 0.001). The rate of M cell induction depended on the macroscopic degree of inflammation. T.E.M./S.E.M. studies showed that in inflamed tissue most M cells underwent apoptosis with typical morphological signs. In contrast to apoptotic M cells, the neighbouring enterocytes usually appeared intact. The number of mononuclear cells below the follicle associated epithelium was significantly increased. S.E.M. studies revealed that during induced ileitis mononuclear cells migrated from the lamina propria into the gut lumen by passing through apoptotic M cells. CONCLUSIONS: During indomethacin-induced ileitis in rats the increase in M cell number in association with apoptosis of M cells may alter the intestinal barrier function. These observations may play a pivotal role in the pathogenesis of chronic intestinal inflammation, e.g. in inflammatory bowel disease.

[Penetrating duodenal ulcer as the primary manifestation of intraductal papillary-mucinous pancreatic tumor]. / Penetrierendes Ulcus duodeni als Primärmanifestation eines intraduktalen papillär-muzinösen Pankreastumors.

A 60-year-old patient with a history of chronic pancreatitis and insulin-dependent diabetes was admitted to our hospital with a deeply excavated duodenal ulcer showing no signs of regression under 4-week parenteral nutrition and proton pump inhibitor therapy. Radiologic and endoscopic diagnostics could demonstrate a primary tumor of the pancreatic head penetrating into the duodenal lumen. After surgical treatment by pylorus-preserving pancreatoduodenectomy an abscessing intraductal papillary-mucinous neoplasm of the pancreas was established morphologically.

Role of M cells in intestinal barrier function.

M cells are known as specialized epithelial cells of the follicle-associated epithelium of the gastrointestinal tract. As M cells have a high capacity for transcytosis of a wide range of microorganisms and macromolecules, they are believed to act as an antigen sampling system. The primary physiological role of M cells seems to be the rapid uptake and presentation of particular antigens and microorganisms to the immune cells of the lymphoid follicle to induce an effective immune response. In contrast to absorptive enterocytes, M cells do not exert direct defense mechanisms to antigens and pathogens in the gut lumen. Therefore, they provide functional openings of the epithelial barrier. Although M cells represent a weak point of the epithelial barrier, even under noninflamed conditions, there seems to be a balance between antigen uptake and immunological response. The low number of M cells in the gastrointestinal tract and the direct contact to immune cells in the lamina propria usually prevent the occurrence of mucosal inflammation. During chronic intestinal inflammation we observe an increase of M cell number and apoptosis selectively in M cells. M cell damage seems to be responsible for the increase of the uptake of microorganisms that is observed during intestinal inflammation. Under inflammatory conditions in the intestine, the maintenance of the epithelial barrier is broken and M cells seem to play a major role during this process.

Interleukin-15 strongly inhibits interleukin-8 and monocyte chemoattractant protein-1 production in human colonic epithelial cells.

Interleukin-15 (IL-15) is a novel cytokine with actions similar to IL-2 because of common receptor components. Although IL-15 is expressed in colonic epithelial cells and may regulate epithelial cell function, its effects on these cells are not fully defined. We explored the regulatory effects of IL-15 on IL-8 and monocyte-chemoattractant protein-1 (MCP-1) production in the colonic epithelial cell line Caco-2 as well as in freshly isolated human colonic epithelial cells. IL-15 was added to intestinal epithelial cells under various culture conditions. Levels of chemokines were determined by enzyme-linked immunosorbent assay. To determine the elements of the IL-2/IL-15R complex involved we used neutralizing antibodies specific for individual receptor chains. IL-15 down-regulates IL-8 and MCP-1 production in Caco-2 cells as well as in freshly isolated human colonic epithelial cells in a dose-dependent manner. Intestinal epithelial cells became more responsive to IL-15-induced suppression when activated with greater IL-1 doses. Strong chemokine suppression was seen when IL-15 was given prior to, simultaneous with, or after stimulatory agent. Anti-IL-2Rgamma antibodies efficiently blocked (82% inhibition) the suppression induced by IL-15, while anti-IL-2Rbeta antibodies were less effective. The involvement of beta-chain was further suggested by the finding that a mixture of both monoclonal antibodies (mAb) at a suboptimal concentration (1 microgram/ml of each mAb) produced a synergistic inhibitory effect on down-regulation of epithelial chemokine production. These results show that IL-15 can suppress IL-8 and MCP-1 secretion by intestinal epithelial cells. A microenvironment containing high concentrations of IL-15 may alter the recruitment of neutrophils to enterocytes at least partly by inhibiting IL-8 and MCP-1 production.

Glucocorticoids induce apoptosis in human monocytes: potential role of IL-1 beta.

Glucocorticoids (GC) are potent anti-inflammatory and immunosuppressive agents that act on a variety of immune cells, including monocytes and macrophages. However, the exact cellular mechanisms underlying this anti-inflammatory capacity are still unknown. In our study, we determined the induction of apoptosis by GC in human monocytes. Peripheral blood monocytes were isolated by density centrifugation methods with a purity of >90% and were cultured in RPMI 1640 medium. Monocyte apoptosis was determined by four independent methods, including annexin-V staining, TUNEL, DNA-laddering, and typical morphology by means of transmission electron microscopy. TNF-alpha and IL-1beta were measured by ELISA. GC receptor was blocked with mifepristone. Caspase 3 was inhibited with caspase-3 inhibitor (DEVD-CHO). Stimulation with different GC at therapeutic concentrations resulted in monocyte apoptosis in a time- and dose-dependent manner. Necrosis was excluded by propidium iodide staining. Proinflammatory cytokines such as IL-1beta and TNF-alpha were down-regulated by GC treatment. Continuous treatment of monocytes with IL-1beta, but not with TNF-alpha, could almost completely prevent GC-induced cell death. The addition of mifepristone or caspase-3 inhibitor could partially abrogate GC-induced apoptosis as well as GC-induced inhibition of IL-1beta. This is the first study to demonstrate induction of apoptosis by GC in human monocytes. GC-induced monocyte apoptosis may be partially mediated through effects on IL-1beta production. It is conceivable that GC exert their anti-inflammatory capacity in various diseases, at least in part, by the induction of apoptosis in monocytes.